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Advanced Techniques in Power Factor Correction (PFC) Prof. Dr. Javier Sebastián Grupo de Electrónica Industrial Universidad de Oviedo (Spain) 11/11/2003 Advanced Techniques in Power Factor Correction 1 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 2 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 3 Introduction (I) Focusing the problem Current DC/DC Electronic converter circuitry Line Power supply Electronic load Cheap & reliable 11/11/2003 Input current with a strong harmonic content Advanced Techniques in Power Factor Correction 4 Introduction (II) Current Distorted Electronic load Line impedance Input voltage Load Line Load Load 11/11/2003 Advanced Techniques in Power Factor Correction 5 Introduction (III) Quantifying the problem Word used to describe the problem Power Factor (PF) Input power PF= Input voltage, rms X Input current, rms Total Harmonic Distortion (THD) (Input current, rms)2 - (Its 1ST harmonic, rms)2 THD= Its 1ST harmonic, rms Each individual harmonic European regulations 11/11/2003 Advanced Techniques in Power Factor Correction 6 Introduction (IV) Conflict of interest Power Companies’ will: Electronic equipment manufacturers’ will: High PF Low cost No harmonics Reliability Regulations about harmonics in the line 11/11/2003 Advanced Techniques in Power Factor Correction 7 Introduction (V) Starting solving the problem (I) Using active filters Electronic load Line impedance Line Electronic load Active Filter 11/11/2003 Electronic load Advanced Techniques in Power Factor Correction 8 Introduction (VI) Starting solving the problem (II) Modifying the electronic load Power Factor Correctors Input current Either Line or New devices DC/DC Electronic converter circuitry Power supply Electronic load Power Factor Corrector 11/11/2003 Advanced Techniques in Power Factor Correction 9 Introduction (VII) However: the value of the Power Factor is not important. According to the European Regulations, only the value of each individual harmonic is important. We should use words such as “Low-Frequency Harmonic Reduction” and “Low-Frequency Harmonic Reducer” instead of “Power Factor Correction” and “Power Factor Corrector”. 11/11/2003 Advanced Techniques in Power Factor Correction 10 Introduction (VIII) Focusing the course Single-Phase AC/DC Line Three-Phase Conversion AC/AC High power Power Low-medium power Reactive Recovery to line energy (230V, <16A) No recovery External connection Connection Modifying AC/DC topology 11/11/2003 Advanced Techniques in Power Factor Correction 11 Introduction (IX) What is the right choice in PFC? It strongly depends on the application. There is not “magic” solutions. It depends on: • The regulations that must be applied • The type of equipment • The output power • The input voltage range • The output voltage • The dynamic response needed • The main objective in the design 11/11/2003 Advanced Techniques in Power Factor Correction 12 Introduction (X) Yes Balanced 3F equipment? Class A The European Regulation No IEC 61000-3-2 Portable tool? Yes Class B No Power supplies are either Class A or Class D Lighting equipment? Yes Class C No PC or TV & P<600 W? Yes Class D No 11/11/2003 Advanced Techniques in Power Factor Correction 13 Introduction (XI) Harmonic limits for Class A and Class D Harmonic 3 5 7 Class A [A] Class D [mA/W] 2.3 3.4 1.14 1.9 0.77 1.0 9 11 13 0.40 0.33 0.21 0.5 0.35 0.296 15 n 39 2.25/n 3.85/n Very Important!! Limits in Class A are absolute values [A] Limits in Class D are relative values [mA/W] 11/11/2003 Advanced Techniques in Power Factor Correction 14 Introduction (XII) Example #1: a 100 W (low-power) converter Harmonic 3 Limits in Class A [mA] 2300 Limits in Class D [mA] 340 5 7 9 11 1140 770 400 330 190 100 50 35 13 15 n 39 210 2250/n 29.6 385/n Limits in Class A are less strict for low-power applications 11/11/2003 Advanced Techniques in Power Factor Correction 15 Introduction (XIII) Example #2: a 500 W (medium-power) converter Harmonic Limits in Class A [mA] Limits in Class D [mA] 3 5 7 2300 1140 770 1700 950 500 9 11 13 15 n 39 400 330 210 2250/n 250 175 148 1925/n Limits in Class A and in Class D become more similar for medium-power applications 11/11/2003 Advanced Techniques in Power Factor Correction 16 Introduction (XIV) Example #1: a 100 W (low-power) battery charger (Class A) Line voltage Line current Battery PF = 0.46 and THD = 193.1% This waveform complies with the regulations!!! Very cheap systems for low-frequency harmonic attenuation can be used to obtain this type of waveform 11/11/2003 Advanced Techniques in Power Factor Correction 17 Introduction (XV) Example #1: a 100 W (low-power) TV set (Class D) Line voltage Line current It does not comply with the regulations Line voltage PF = 0.748 and THD = 88.8% 11/11/2003 Line current A slightly more complex system must be used (it is still very simple) Advanced Techniques in Power Factor Correction 18 Introduction (XVI) Example #2: two 500 W (low-power) pieces of equipment Class D Class A Line voltage PF = 0.705 and THD = 100.5% Line current Line voltage Line current PF = 0.748 and THD = 88.8% The advantages of being Class A vanish at 500 W 11/11/2003 Advanced Techniques in Power Factor Correction 19 Introduction (XVII) Example #3: same Class, different power Line voltage PF = 0.705 and THD = 100.5% Line current Line voltage Line current PF = 0.963 and THD = 28.1% The complexity of the systems for low-frequency harmonic attenuation increases with the power 11/11/2003 Advanced Techniques in Power Factor Correction 20 Introduction (XVIII) Influence of the input voltage range (I) European range: 190 Vac – 265 Vac American range: 85 Vac – 130 Vac Universal range: 85 Vac – 265 Vac Two ranges (American and European), but a mechanical switch permitted for changing the range 11/11/2003 Advanced Techniques in Power Factor Correction 21 Introduction (XIX) Influence of the input voltage range (II) Single range (either European or American) and simple system for low-frequency harmonic attenuation (PFC) Moderate change in the input voltage of the DC/DC converter Slight penalty in efficiency Line Simple PFC with single range 11/11/2003 PFC DC/DC Electronic converter circuitry Power supply Electronic load Advanced Techniques in Power Factor Correction 22 Introduction (XX) Influence of the input voltage range (III) Universal range and simple PFC Large change in the input voltage of the DC/DC converter Significant penalty in efficiency Complex PFCs which guaranty constant input voltage are interesting Line Complex PFC with universal range 11/11/2003 PFC DC/DC Electronic converter circuitry Power supply Electronic load Advanced Techniques in Power Factor Correction 23 Introduction (XXI) Influence of the input voltage range (IV) Two ranges selected by a switch Power supply for single range without PFC DC/DC Electronic converter circuitry Power supply Electronic load Power supply for double range without PFC 230V 110V Is it compatible with the use of simple PFC? 11/11/2003 DC/DC Electronic converter circuitry Power supply Advanced Techniques in Power Factor Correction Electronic load 24 Introduction (XXII) Influence of the input voltage range (V) Two ranges selected by a switch and PFC Simple PFC 230V Simple PFC placed on the DC side 110V DC/DC converter Simple PFC Power supply Simple PFC placed on the AC side Simple PFC 230V 110V DC/DC converter Power supply 11/11/2003 Advanced Techniques in Power Factor Correction 25 Introduction (XXIII) Changing the place of the DC/DC converter Resistor Emulator concept Current DC/DC Electronic converter circuitry Line Power supply DC/DC converter as Current Line Resistor Emulator Power supply 11/11/2003 Advanced Techniques in Power Factor Correction Electronic load Electronic circuitry Electronic load 26 Introduction (XXIV) Using only a Resistor Emulator (I) Energy stored at high voltage (325 V DC) small size Energy stored at the output voltage the size depends on the voltage converter Line Current Line Power supply DC/DC converter as Output DC/DC Output Current Resistor Emulator Power supply It is not a good solution for low-voltage (<12 V DC) applications 11/11/2003 Advanced Techniques in Power Factor Correction 27 Voltage Voltage Current Power DC/DC converter Line Power supply DC/DC converter as Resistor Emulator Line Power supply Energy stored here The converter is in charge of cancelling the output ripple It is not a good solution when low output-ripple is needed 11/11/2003 Power Output Current Using only a Resistor Emulator (II) Output Introduction (XXV) No devices to store energy at 100 Hz Little (or no) power processed at specific moments the output ripple depends on the capacitor Advanced Techniques in Power Factor Correction 28 Introduction (XXVI) Using only a Resistor Emulator (III) Power Voltage Power Current Current converter Line DC/DC converter as Line Power supply Output DC/DC Output Voltage Resistor Emulator Power supply Energy stored here No devices to store energy at 100 Hz The converter can get energy from the capacitor to maintain the output voltage when the output current changes It is not a good solution when fast transient response is needed 11/11/2003 Little (or no) power processed at specific moments no energy available to maintain the output voltage when the output current changes Advanced Techniques in Power Factor Correction 29 Introduction (XXVII) Two separate stages In the case of fast transient response needed: Line Simple or complex DC/DC Electronic converter circuitry PFC Power supply One integrated stage Line A DC/DC converter (or section) is needed 11/11/2003 Simple PFC converter section section DC/DC Electronic circuitry Power supply Advanced Techniques in Power Factor Correction 30 Introduction (XXVIII) What are the design priorities? Cost Size Weight Efficiency Only comply with the regulations High Power Factor and low Total Harmonic Distortion (for marketing reasons) They also determine the right choice 11/11/2003 Advanced Techniques in Power Factor Correction 31 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 32 Using a resistor (I) Looking for the simplest solution (I) DC/DC converter Line 200 mF 4 X 1N4007 (120 W) Power supply Capacitor voltage Class D Input current 11/11/2003 Advanced Techniques in Power Factor Correction 33 Using a resistor (II) Looking for the simplest solution (II) Input current Input current [A] 0.6 Limits in Class D 0.4 Simulated 0.2 0 0 5 10 15 20 25 Harmonic order 30 35 40 The compliance is very far 11/11/2003 Order Measured [A] Limits Class D [A] 1 0.542 - 3 0.527 0.408 5 0.498 0.228 7 0.457 0.12 9 0.407 0.06 11 0.351 0.042 13 0.294 0.036 15 0.239 0.031 17 0.192 0.027 19 0.155 0.024 21 0.132 0.022 23 0.121 0.02 25 0.117 0.018 27 0.115 0.017 29 0.112 0.016 31 0.105 0.015 33 0.097 0.014 35 0.087 0.013 37 0.079 0.012 39 0.073 0.012 Advanced Techniques in Power Factor Correction 34 Using a resistor (III) Looking for the simplest solution (III) What about a Class A piece of equipment? DC/DC converter Line 200 mF (120 W) Battery Charger 4 X 1N4007 Battery Capacitor voltage Class A Input current 11/11/2003 Advanced Techniques in Power Factor Correction 35 Using a resistor (IV) Looking for the simplest solution (IV) Input current Input current 2.5 [A] 2 Limits in Class A 1.5 Simulated 1 0.5 0 0 5 10 15 20 25 30 Harmonic order 35 It does not comply, but it is very near to comply 11/11/2003 40 Order Measured [A] Limits Class A [A] 1 0.542 - 3 0.527 2.3 5 0.498 1.14 7 0.457 0.77 9 0.407 0.4 11 0.351 0.33 13 0.294 0.21 15 0.239 0.15 17 0.192 0.132 19 0.155 0.118 21 0.132 0.107 23 0.121 0.098 25 0.117 0.09 27 0.115 0.083 29 0.112 0.078 31 0.105 0.073 33 0.097 0.068 35 0.087 0.064 37 0.079 0.061 39 0.073 0.058 Advanced Techniques in Power Factor Correction 36 Using a resistor (V) Looking for the simplest solution (V) Let us change the value of the bulk capacitor DC/DC converter Line 100 mF 4 X 1N4007 (120 W) Battery Charger Capacitor voltage Input current Almost compliance with 100 mF 11/11/2003 Order Measured [A] Limits Class A [A] 1 0.528 - 3 0.5 2.3 5 0.448 1.14 7 0.378 0.77 9 0.3 0.4 11 0.225 0.33 13 0.164 0.21 15 0.128 0.15 17 0.115 0.132 19 0.113 0.118 21 0.109 0.107 23 0.1 0.098 25 0.087 0.09 27 0.076 0.083 29 0.07 0.078 31 0.067 0.073 33 0.066 0.068 35 0.063 0.064 37 0.058 0.061 39 0.053 0.058 Advanced Techniques in Power Factor Correction 37 Using a resistor (VI) Looking for the simplest solution (VI) However, the value of the bulk capacitor cannot be freely chosen because: Hold-up time requirements Input voltage range of the DC/DC converter Another solution must be found 11/11/2003 Advanced Techniques in Power Factor Correction 38 Using a resistor (VII) The simplest solution: to add a resistor DC side R DC/DC Line converter Electronic circuitry Class A Power supply AC side R DC/DC Line converter Electronic circuitry Class A Power supply 11/11/2003 Advanced Techniques in Power Factor Correction 39 Using a resistor (VIII) Order Measured [A] with R=0 W Measured [A] with R=1 W Measured [A] with R=1.5 W Limits Class A [A] 1 0.542 0.539 0.538 - 3 0.527 0.52 0.516 2.3 5 0.498 0.484 0.474 1.14 7 0.457 0.433 0.416 0.77 9 0.407 0.372 0.347 0.4 11 0.351 0.304 0.273 0.33 13 0.294 0.237 0.2 0.21 15 0.239 0.173 0.135 0.15 17 0.192 0.12 0.084 0.132 19 0.155 0.084 0.056 0.118 21 0.132 0.067 0.053 0.107 23 0.121 0.066 0.057 0.098 25 0.117 0.067 0.058 0.09 27 0.115 0.065 0.052 0.083 29 0.112 0.058 0.041 0.078 31 0.105 0.047 0.029 0.073 33 0.097 0.036 0.021 0.068 35 0.087 0.028 0.02 0.064 37 0.079 0.025 0.022 0.061 39 0.073 0.026 0.024 0.058 11/11/2003 Advanced Techniques in Power Factor Correction Cbulk = 200 mF Pconverter = 120 W @ 230V ac, R =1.5 W iinput peak = 4.12 A Presistor = 1.85 W 40 Using a resistor (IX) Input-current waveform with a resistor Cbulk = 200 mF Pconverter = 120 W Capacitor voltage Capacitor voltage Input current Input current @ 230V ac, R =1.5 W iinput peak = 4.12 A Presistor = 1.85 W 11/11/2003 @ 230V ac, R =0 W iinput peak = 6.37 A Advanced Techniques in Power Factor Correction 41 Using a resistor (X) Design procedure Choose bulk capacitor Input power Obtain the resistor (from graphs) Calculate losses @ full power, 190 Vac Other NO Acceptable YES Use the simplest method must losses? method be used 11/11/2003 Advanced Techniques in Power Factor Correction 42 Using a resistor (XI) Value of the resistor needed to comply with the IEC 61000-3-2 in Class A as a function of the input power (bulk capacitor in mF per watt as parameter) R [W] 4 3 2 mF/W 2 1 50 1 mF/W 100 0.5 mF/W 150 200 250 300 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 43 Using a resistor (XII) Absolute power losses at full load and minimum line voltage (maximum line current) Power losses [W] 25 20 15 1 mF/W 0.5 mF/W 10 2 mF/W 5 50 100 150 200 250 300 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 44 Using a resistor (XIII) Relative power losses (PR/Poutput) at full load and minimum line voltage (maximum line current) Relative losses [%] 10 8 1 mF/W 6 4 2 mF/W 2 0.5 mF/W 50 100 150 200 250 300 Output Power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 45 Using a resistor (XIV) Design example: Poutput=150W, C=150mF (1mF/W) R [W] 4 3 2.5 W 2 1 50 1 mF/W 100 150 200 250 300 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 46 Using a resistor (XV) Power losses in the resistor at Poutput=150W and Vline=190V Power losses [W] 25 20 15 1 mF/W 10 5W 5 50 100 150 200 250 300 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 47 Using a resistor (XVI) Power limits for this solution Relative losses [%] 10 8 6 Very interesting 4 1 mF/W Not so interesting 2 50 100 150 200 250 300 Output Power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 48 Using a resistor (XVII) Using this solution for Universal line voltage range Pconverter = 120 W Cbulk = 200 mF R=1.5 W R DC/DC Line Cbulk 4 X 1N4007 Line @ 230V @ 110V iinput peak 4.12 A 5.09A iinput RMS 1.11 A 1.853 A Plosses resistor 1.85 W 5.15 W converter Pconverter Power supply Quantity 11/11/2003 Advanced Techniques in Power Factor Correction Power losses strongly increase at low line voltage 49 Using a resistor (XVIII) DC side Adaptation for operation in two ranges (I) R/2 230V DC/DC Line converter 110V R/2 Electronic circuitry Class A Power supply AC side Line R 230V 110V DC/DC converter Electronic circuitry Class A Power supply Different operation (AC side & DC side) 11/11/2003 Advanced Techniques in Power Factor Correction 50 Using a resistor (XIX) AC side Adaptation for operation in two ranges (II) R iinput 110V 230V Line 110V DC/DC converter Electronic circuitry Class A Power supply R iinput 230V 230V Line 110V DC/DC converter Electronic circuitry Class A Power supply Both iinput 110V and iinput 230V passing through R 11/11/2003 Advanced Techniques in Power Factor Correction 51 Using a resistor (XX) DC side iinput 110V Adaptation for operation in two ranges (III) R/2 230V DC/DC converter 110V Line R/2 Electronic circuitry Class A Power supply iinput 230V R/2 230V DC/DC converter 110V Line R/2 Electronic circuitry Class A Power supply iinput 110V passing through R/2 and iinput 230V passing through R (better) 11/11/2003 Advanced Techniques in Power Factor Correction 52 Using a resistor (XXI) Adaptation for operation in two ranges (IV) Example: Pconverter = 120 W Cbulk = 2 X 400 mF (series) R=1.5 W R/2 110V Electronic 230V DC/DC Line R/2 Plosses resistors = 3.15 W (total) converter 110V 110V 230V Line 110V 11/11/2003 Class A Power supply R Plosses resistor = 5.27 W circuitry DC/DC converter Electronic circuitry Class A Power supply Advanced Techniques in Power Factor Correction 53 Using a resistor (XXII) Adaptation for operation in two ranges (V) C R 230V DC/DC Line 110V converter Electronic circuitry Class A C Power supply Power R C losses @ 230V losses losses @ 190V @ 110V losses @ 85V 100 W 1.6 W 2x220 mF 1.3 W 1.6 W 3.8 W 5W 200 W 3.6 W 2x440 mF 8.5 W 11.5 W 29 W 50 W Impractical due to the fact that the power losses strongly increase at low line voltage 11/11/2003 Advanced Techniques in Power Factor Correction 54 Using a resistor (XXIII) Adaptation for operation in two ranges (VI) C R/2 Electronic 230V DC/DC Line R/2 converter 110V circuitry Class A C Power supply Power R C losses @ 230V losses losses @ 190V @ 110V losses @ 85V 100 W 1.6 W 2x220 mF 1.3 W 1.6 W 2.1 W 3.1 W 200 W 3.6 W 2x440 mF 8.5 W 11.5 W 16 W 25 W Better results with the resistor split into two resistors 11/11/2003 Advanced Techniques in Power Factor Correction 55 Using a resistor (XXIV) Experimental results (I) Pconverter = 100 W C = 2 X 100 mF (series) R = 2x0.82 W R/2 230V Line C 110V 1 A/div R/2 C Input current [A] 2.5 @ 230V, 100W @ 230V, 100W, 2x0.82W, 2W 2 1.5 Limits in Class A 2 A/div 1 Measured 0.5 @ 110V, 100W 0 3 7 11 15 19 23 27 31 35 Harmonic Order 11/11/2003 Advanced Techniques in Power Factor Correction 56 Using a resistor (XXV) Experimental results (II) Pconverter = 200 W C = 2 X 200 mF (series) R= 2x1.8 W R/2 230V Line C 110V 2 A/div R/2 C Input current [A] @ 230V, 200W 2.5 @ 230V, 200W, 2x1.8W, 10W 2 1.5 2 A/div Limits in Class A 1 Measured 0.5 @ 110V, 200W 0 3 7 11 15 19 23 27 31 35 Harmonic Order 11/11/2003 Advanced Techniques in Power Factor Correction 57 Using a resistor (XXVI) Conclusions of the use of a resistor to comply with the IEC 61000-3-2 regulations in Class A This is the simplest possible solution Low-cost and low-size solution Very interesting for low-power (P<200-300W) applications High losses with universal line voltage range (only valid for P<150W) The DC bus is not regulated For the universal line voltage and with a voltage-doubler with a mechanical switch, it can be used up to 200W No perfect sinusoidal, but compliance with IEC 61000-3-2 is achieved 11/11/2003 Advanced Techniques in Power Factor Correction 58 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 59 Using an inductor (I) Another very simple solution: to add an inductor DC side L DC/DC Line converter Electronic circuitry Class A Power supply AC side L DC/DC Line converter Electronic circuitry Class A Power supply 11/11/2003 Advanced Techniques in Power Factor Correction 60 Using an inductor (II) Order Measured [A] with L=0 mH Measured [A] with L=1 mH Measured [A] with L=2 mH Limits Class A [A] 1 0.542 0.552 0.545 - 3 0.527 0.531 0.515 2.3 5 0.498 0.493 0.459 1.14 7 0.457 0.438 0.384 0.77 9 0.407 0.374 0.299 0.4 11 0.351 0.303 0.214 0.33 13 0.294 0.232 0.138 0.21 15 0.239 0.167 0.079 0.15 17 0.192 0.11 0.046 0.132 19 0.155 0.067 0.039 0.118 21 0.132 0.042 0.04 0.107 23 0.121 0.036 0.036 0.098 25 0.117 0.037 0.028 0.09 27 0.115 0.037 0.02 0.083 29 0.112 0.032 0.017 0.078 31 0.105 0.025 0.016 0.073 33 0.097 0.019 0.016 0.068 35 0.087 0.016 0.014 0.064 37 0.079 0.015 0.011 0.061 39 0.073 0.015 0.009 0.058 11/11/2003 Advanced Techniques in Power Factor Correction Cbulk = 200 mF Pconverter = 120 W @ 230V ac, L = 2 mH iinput peak = 3.84 A 61 Using an inductor (III) Input-current waveform and harmonic content with an inductor Capacitor voltage Example: Cbulk = 200 mF Pconverter = 120 W L = 2 mH Input current Input current Input current 0.6 [A] 2.5 Limits in Class 1.5 Limits in Class 0.4 A It does not comply 0.2 It complies 0.5 D Simulated Simulated 1 0 @ 230V, 120 W @ 230V, 120 W 2 [A] 0 0 5 10 11/11/2003 15 20 25 Harmonic order 30 35 40 0 5 Advanced Techniques in Power Factor Correction 10 15 20 25 Harmonic order 30 35 62 40 Using an inductor (IV) Comparing input-current waveform with an inductor and a resistor for Class A equipment Cbulk = 200 mF Pconverter = 120 W Capacitor voltage Capacitor voltage Input current Input current @ 230V ac, R =1.5 W iinput peak = 4.12 A Presistor = 1.85 W 11/11/2003 @ 230V ac, L = 2 mH iinput peak = 3.84 A Advanced Techniques in Power Factor Correction 63 Using an inductor (V) Comparing input-current waveforms with different bulk capacitor values L = 3.3 mH Pconverter = 400 W 340 V 288 V 312 V 8.38 A 300 V 7.55 A Capacitor voltage Input current C = 200 mF Input current 0 10 ms 0 C = 800 mF 0 Capacitor voltage 20 ms 10 10 ms C = 200 mF 20 ms 5 Slightly influence of the capacitor value C = 800 mF 0 0 11/11/2003 Advanced Techniques in Power Factor Correction 10 ms 64 Using an inductor (VI) Looking for the most restrictive harmonics (I) Example: 100 W, 1.7 mH & 47 mF Input current [A] 5 3.85 A Input current [A] 3.5 @ 230V, 100 W, 1.7 mH & 47 mF 3 0 2.5 Limits in Class A 2 Simulated 1.5 -5 0 1 20 ms 10 ms Time 0.5 3 5 7 9 11 13 15 Harmonic Order 11/11/2003 17 19 Harmonics 13th-17th are the most restrictive at low power Advanced Techniques in Power Factor Correction 65 Using an inductor (VII) Looking for the most restrictive harmonics (II) Input current [A] Example: 600 W, 7.8 mH & 330 mF 10 8.68 A Input current [A] 0 3.5 @ 230V, 600 W, 7.8 mH & 330 mF 3 2.5 Limits in Class A 2 -10 0 Time Simulated 1.5 20 ms 10 ms 1 0.5 3 5 7 9 11 13 15 Harmonic Order 11/11/2003 17 19 Harmonics 3rd-5th are the most restrictive at high power Advanced Techniques in Power Factor Correction 66 Using an inductor (VIII) Value of the minimum inductor needed to comply with the IEC 61000-3-2 in Class A as a function of the input power (bulk capacitor in mF per watt as parameter) L [mH] 8 6 0.5 mF/W 4 2 mF/W 2 100 200 300 400 500 600 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 67 Using an inductor (IX) Comparing the influence of the bulk capacitor for the case of the inductor and the resistor L [mH] R [W] 8 4 6 0.5 mF/W 3 1 mF/W 4 2 mF/W 2 2 mF/W 1 2 50 100 200 300 400 500 0.5 mF/W 100 150 200 250 300 Output power [W] 600 Output power [W] Lower inductor values with high bulk capacitor values 11/11/2003 Erratic influence of the value of the bulk capacitor Advanced Techniques in Power Factor Correction 68 Using an inductor (X) Choose bulk capacitor Design procedure for Class A Input power Obtain the inductor (from graphs) Calculate the inductor size Other NO Acceptable YES method must Use this method size? be used 11/11/2003 Advanced Techniques in Power Factor Correction 69 Using an inductor (XI) Design example: Poutput=200 W, C=100 mF (0.5 mF/W) L [mH] 8 6 0.5 mF/W 4 2 mF/W 2.7 mH 2 100 200 300 400 500 600 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 70 Using an inductor (XII) What about the inductor size? We must know the maximum peak value of the input current (at full load and minimum line voltage) determine the gap and number of turns We must know the maximum RMS value of the input current (at full load and minimum line voltage) determine the wire size (diameter) and losses Input power [W] L [mH] Ipeak [A] 200 2.7 5.33 @ 230V 6.07 @ 190V 11/11/2003 IRMS [A] Equivalent ferrite core size Power losses (%) 1.6 @ 230V 1.88 @ 190V E30/15/7 0.8 Advanced Techniques in Power Factor Correction 71 Using an inductor (XIII) 11/11/2003 Inductor size and losses for different power levels L [mH] Equivalent ferrite core size Power losses (%) 100 2 E20/10/5 0.53 200 2.7 E30/15/7 0.8 300 3.4 E42/21/15 0.3 400 4.4 E42/21/15 0.66 500 6.8 E42/21/20 0.57 600 7.8 E42/21/20 1.66 Input power [W] Advanced Techniques in Power Factor Correction 72 Using an inductor (XIV) Magnetic materials for the inductor (I) Silicon steel lamination core (instead of ferrite) Example: RG11 B [T] 2 1.5 1 0.5 10 Plosses [kw/m3] 100 1000 10000 100000 H [A/m] 100 10 High induction levels (1.4 T) are possible 1 0.1 0.01 10 11/11/2003 100 B [mT] 1000 10000 Advanced Techniques in Power Factor Correction 73 Using an inductor (XV) 11/11/2003 Magnetic materials for the inductor (II) Advanced Techniques in Power Factor Correction 74 Using an inductor (XVI) DC-side or AC-side inductor? Example: Cbulk = 200 mF, L = 2 mH, Pconverter = 120 W with AC-side inductor DC-side inductor with DC-side inductor Capacitor voltage Line current Time with AC-side inductor AC-side inductor with DC-side inductor Exactly the same result if the converter is working in strong DCM 11/11/2003 Advanced Techniques in Power Factor Correction 75 Using an inductor (XVII) What about complying with the IEC 61000-3-2 regulations in Class D? Example: Cbulk = 200 mF, L = 2 mH, Pconverter = 120 W Input current 0.6 [A] @ 230V, 120 W Limits in Class 0.4 D Simulated 0.2 0 0 5 10 15 20 25 Harmonic order 30 35 40 Low-frequency harmonics are the most significant ones A considerable increase in the inductance value is needed 11/11/2003 Advanced Techniques in Power Factor Correction 76 Using an inductor (XVIII) Looking for the minimum value of L to comply with the regulations in Class D (I) Example: Cbulk = 200 mF, L = 41 mH, Pconverter = 100 W Input current [A] Input current [A] 0.5 2 @ 230V, 100W, 41mH & 200mF 1.42 A 0.4 1 Limits in Class D @ 100W 0.3 0 0.2 Simulated -1 0.1 -2 0 10 ms 20 ms 3 5 7 Time 9 11 13 15 17 19 Harmonic Order An inductor of 41 mH is needed for 100 W 11/11/2003 Advanced Techniques in Power Factor Correction 77 Using an inductor (XIX) Looking for the minimum value of L to comply with the regulations in Class D (II) If we increase the power, the limits will also increase a similar input-current waveform is enough to comply with the regulations Example: Cbulk = 1200 mF, L = 7 mH, Pconverter = 600 W Input current [A] Input current [A] 3 10 @ 230V, 600W, 7mH & 1200mF 8.12 A 2.5 2 Limits in Class D @ 600W 0 1.5 1 Simulated 0.5 -10 0 10 ms 20 ms Time 0 3 5 7 9 11 13 15 17 19 Harmonic Order An inductor of 7 mH is needed for 600 W 11/11/2003 Advanced Techniques in Power Factor Correction 78 Using an inductor (XX) Value of the minimum inductor needed to comply with the IEC 61000-3-2 in Class D as a function of the input power (bulk capacitor in mF per watt as parameter) L [mH] 50 The value of the inductor’s inductance decreases when the power increases, but the size increases (because it depends on the square value of the peak current) 40 30 0.5 mF/W 20 2 mF/W 10 100 200 300 400 500 600 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 79 Using an inductor (XXI) 11/11/2003 Inductor size and losses for different power levels L [mH] Equivalent ferrite core size Power losses (%) 100 41 E42/21/15 1 200 21 E42/21/15 2 300 14 E42/21/20 1.1 400 10 E42/21/20 1.25 500 8.7 E42/21/20 1.8 600 6.9 E42/21/20 2.18 Input power [W] Advanced Techniques in Power Factor Correction 80 Using an inductor (XXII) Comparing the value of the minimum inductor needed to comply with the IEC 61000-3-2 in Class A and in Class D L [mH] L [mH] 8 50 Minimum inductor to comply in Class A Minimum inductor to comply in Class D 40 6 0.5 mF/W 30 0.5 mF/W 4 20 2 mF/W 2 mF/W 2 10 100 200 300 400 500 600 100 300 400 500 Output power [W] Output power [W] Lower L values at low power 11/11/2003 200 Similar L values at high power Advanced Techniques in Power Factor Correction 81 600 Using an inductor (XXIII) Inductor size and losses for different power levels Input power [W] L [mH] in Class A Equivalent core size in Class A Power losses in Class A (%) L [mH] in Class D Equivalent core size in Class D Power losses in Class D (%) 100 2 E20/10/5 0.53 41 E42/21/15 1 200 2.7 E30/15/7 0.8 21 E42/21/15 2 300 3.4 E42/21/15 0.3 14 E42/21/20 1.1 400 4.4 E42/21/15 0.66 10 E42/21/20 1.25 500 6.8 E42/21/20 0.57 8.7 E42/21/20 1.8 600 7.8 E42/21/20 1.66 6.9 E42/21/20 2.18 Lower L sizes at low power in Class A 11/11/2003 Similar L sizes at high power Advanced Techniques in Power Factor Correction 82 Using an inductor (XXIV) DC side Adaptation for operation in two ranges (I) L/2 230V Line 110V L/2 AC side Line DC/DC converter Electronic circuitry Class A Power supply L 230V 110V DC/DC converter Electronic circuitry Class A Power supply Different operation (AC side & DC side) 11/11/2003 Advanced Techniques in Power Factor Correction 83 Using an inductor (XXV) AC side Adaptation for operation in two ranges (II) L iinput 110V 230V Line 110V DC/DC converter Electronic circuitry Class A Power supply L iinput 230V 230V Line 110V DC/DC converter Electronic circuitry Class A Power supply Both iinput 110V and iinput 230V passing through L 11/11/2003 Advanced Techniques in Power Factor Correction 84 Using an inductor (XXVI) Adaptation for operation in two ranges (II) DC side iinput 110V L/2 230V DC/DC converter 110V Line L/2 Electronic circuitry Class A Power supply iinput 230V L/2 230V DC/DC converter 110V Line L/2 Electronic circuitry Class A Power supply iinput 110V passing through L/2 and iinput 230V passing through L 11/11/2003 Advanced Techniques in Power Factor Correction 85 Using an inductor (XXVII) Experimental results (I) L Class D Line Pconverter = 100 W C = 47 mF C L = 41 mH Input current [A] 0.5 A/div @ 230V, 100W, 41 mH 0.3 0.2 Limits in Class D @ 230V, 100W 0.1 Measured 5 9 13 17 21 25 29 33 37 Harmonic order 11/11/2003 Advanced Techniques in Power Factor Correction 86 Using an inductor (XXVIII) Experimental results (II) Class A L Pconverter = 100 W C = 47 mF Line C L = 1.7 mH Input current [A] 1 A/div @ 230V, 100W, 1.7 mH 2 Limits in Class A @ 230V, 100W 1 Measured 3 9 11 15 19 23 27 31 35 Harmonic order 11/11/2003 Advanced Techniques in Power Factor Correction 87 Using an inductor (XXVIII) Conclusions of the use of an inductor to comply with the IEC 61000-3-2 regulations in Class A and Class D This is a very simple solution Low-cost and high-efficiency (low-losses) solution Very interesting for low-power (P<200-300W) applications in Class A Large inductor size for Class D and high-power Class A The DC bus is not regulated For the universal line voltage range, a voltage doubler with a mechanical switch can be implemented to improve the circuit operation No perfect sinusoidal waveform, but compliance with the IEC 61000-3-2 regulations 11/11/2003 Advanced Techniques in Power Factor Correction 88 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 89 Using only a RE (I) Passive (L or R) versus active systems to reduce the harmonic content R or L DC/DC Line converter Output Current Resistor Emulator Line Power supply 11/11/2003 capacitor solutions for limited line voltage range (many times, voltage doubler needed) Output Current solutions for low power Unregulated voltage across the Power supply DC/DC converter as Low-cost Either low-losses or low-size Non-sinusoidal waveform Sinusoidal waveform solutions for any power Regulated voltage across the capacitor solutions for universal line voltage range A good solution if only the Resistor Emulator were enough Advanced Techniques in Power Factor Correction 90 Is only a Resistor Emulator enough to implement the overall power supply? R or L DC/DC converter Output Energy stored at high voltage (325 V DC) small size Energy stored at the output voltage the size depends on the voltage Power supply DC/DC converter as Output Using only a RE (II) Resistor Emulator Power supply From the point of view of the capacitor size, it is not a bad solution for medium and high voltage applications (>12 V DC) 11/11/2003 Advanced Techniques in Power Factor Correction 91 Using only a RE (III) And, what about the dynamics? Example of Resistor Emulator control: control based on an analog multiplier DC/DC converter Lowpass filter 11/11/2003 Advanced Techniques in Power Factor Correction Why a lowpass filter here? 92 Using only a RE (IV) Filter with verylow cut-off frequency Input voltage The lowpass filter influence (I) DC/DC converter Filter with high cut-off frequency Input voltage Vea Vea Current Reference= Vea·Sinus 11/11/2003 Vea Current Reference= Vea·Sinus Lowpass filter A filter with low cut-off frequency is needed if a perfect sinusoidal is required Advanced Techniques in Power Factor Correction 93 Using only a RE (V) The lowpass filter influence (II) And, what about the dynamic response? DC/DC converter Filter with very low cut-off frequency: Perfect sinusoidal line current Very poor dynamic response Vea Filter with high cut-off frequency: Non-perfect sinusoidal line current But, can we achieve compliance with the IEC 61000-3-2 and reasonable dynamic response? 11/11/2003 Lowpass filter If yes, the use of only a Resistor Emulator as overall power supply becomes very attractive Advanced Techniques in Power Factor Correction 94 Using only a RE (VI) Line current waveform as a function of the voltage regulator pole frequency fp AR [dB] 60 Voltage regulator 40 20 0 -20 fp: 500 Hz fp: 100 Hz fp: 1000 Hz AR -40 [º] 45 0 -45 -90 fp: 10 Hz time -135 1 fp = 1kHz is a practical limit (no significant phase shift at 100Hz) 11/11/2003 Advanced Techniques in Power Factor Correction 10 100 1000 10000 f [Hz] fp fp fp f p 95 Using only a RE (VII) Line current waveform as a function of the voltage regulator DC gain AR AR = 50 AR = 100 fp: 10 Hz fp: 100 Hz fp: 500 Hz fp: 1000 Hz 11/11/2003 Advanced Techniques in Power Factor Correction AR = 100 is a practical limit due to the voltage levels in the controller 96 Using only a RE (VIII) Looking for the worst case Input current [A] Line current 3 Limits in Class D @ 100W 2.3 A fp1000 Hz 2 AR 100 Simulated 1 0 3 11 21 31 39 Harmonic Order Theoretical harmonic content: Only the third harmonic is present 11/11/2003 Advanced Techniques in Power Factor Correction 97 Using only a RE (IX) For 0wt Why is the third harmonic the only one present in the line current? (I) V1sinwt iline DC DC/DC converter V1sinwt Veao+ Veasin2wt Rs Viref= V1sinwt· (Veao+ Veasin2wt) Viref Vea Lowpass filter Viref(wt) = VeaoV1sinwt + 0.5V1Veacoswt - 0.5V1Veacos3wt iline DC (wt) = (VeaoV1sinwt + 0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs Therefore, for 0wt iline AC (wt) = iline DC (wt) = (VeaoV1sinwt + 0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs 11/11/2003 Advanced Techniques in Power Factor Correction 98 Using only a RE (X) Why is the third harmonic the only one present in the line current? (II) iline DC (wt) wt- Due to the fact that the frequency of iline DC is 2w iline DC (wt) = iline DC (wt-) wt iline AC (wt) Due to the line rectifier: iline AC (wt) = iline DC (wt) if 0wtand -iline DC (wt) if -wt0 For – wt 0 iline AC (wt) = -iline DC (wt) = -iline DC (wt-) = -(VeaoV1sin(wt-) + 0.5V1Veacos(wt-) 0.5V1Veacos3(wt-))/Rs = (VeaoV1sinwt + 0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs Therefore, for -wt iline AC (wt) = (VeaoV1sinwt + 0.5V1Veacoswt - 0.5V1Veacos3wt)/Rs There are only components of w and 3w 11/11/2003 Advanced Techniques in Power Factor Correction 99 Using only a RE (XI) Line current Looking for the maximum power compatible with complying with the IEC 61000-3-2 regulations in Class A (I) fp1000 Hz AR 50-100 AR Output ripple=1 % Output ripple=2 % 50 3680 W 3400 W 100 3400 W 1700 W IEC 61000-3-2 regulations in Class A can be complied up to very high power levels 11/11/2003 Advanced Techniques in Power Factor Correction 100 Using only a RE (XII) Looking for the maximum power compatible with complying with the IEC 61000-3-2 regulations in Class A (II) Line current obtained by simulation 3 AR = 100, fC: 500 Hz 2 1 0 Theoretical Simulated 3 AR = 100, fC: 1 kHz 2 1 0 Theoretical Simulated The theoretical and the simulated waveforms are slightly different The cause is the output voltage ripple. Due to this, the actual ripple is not exactly sinusoidal AR Output ripple=1 % Output ripple=2 % 50 3600 W 2500 W 100 2600 W 1300 W Compliance up to very high power levels is achieved 11/11/2003 Advanced Techniques in Power Factor Correction 101 Using only a RE (XIII) Can we get a very fast transient response if we have a very fast output voltage feedback loop? Power Voltage DC/DC converter as Resistor Emulator Line Output Current Power supply No devices to store energy at 100 Hz 11/11/2003 Energy stored here Little (or no) power processed at specific moments no energy available to maintain the output voltage when the output current changes, except the energy stored in the capacitor The dynamics depends on the capacitor The capacitor is recharged each 10ms (100 Hz) the faster response is 10 ms Advanced Techniques in Power Factor Correction 102 Using only a RE (XIV) Simulating the dynamic response fC = 10 Hz Output voltage 420 fC = 1kHz Output voltage 410 400 400 390 40 ms 380 380 360 90 ms 370 4300 W 1700 W 20 40 60 80 100 120 10 ms 2600 W 360 140 160 20 Time (ms) 60 80 100 120 Time (ms) The output voltage takes 90 ms in recovering the steady state 11/11/2003 40 400 W The output voltage takes 10 ms in recovering the steady state Advanced Techniques in Power Factor Correction 103 Using only a RE (XV) Resistor Emulator topologies: low power Voltage Flyback based Current Line Power supply Load (Electronic circuitry) Voltage SEPIC based Current Load Line 11/11/2003 Power supply Advanced Techniques in Power Factor Correction (Electronic circuitry) 104 Using only a RE (XVI) Resistor Emulator topologies: medium power Current-fed Push-Pull based Voltage Current Load (Electronic Line circuitry) Power supply Voltage Current Load (Electronic Line circuitry) Power supply 11/11/2003 Advanced Techniques in Power Factor Correction 105 Using only a RE (XVII) Resistor Emulator topologies: high power Current-fed Full-bridge based Voltage Current Load (Electronic Line circuitry) Power supply Voltage Current Load (Electronic Line circuitry) Power supply 11/11/2003 Advanced Techniques in Power Factor Correction 106 Using only a RE (XVIII) Example of application: a power supply for a 300 + 300 W audio amplifier (I) Flyback based +70 V Line 85-250 V 300 W audio amplifier (Channel Right) GND 300 W audio amplifier (Channel Left) Power supply -70 V Universal line voltage Flyback with 2 Cool-MOS in parallel 10 ms dynamic response is good enough for this application 11/11/2003 Advanced Techniques in Power Factor Correction 107 Using only a RE (XIX) Example of application: a power supply for a 300 + 300 W audio amplifier (II) 300 + 300 W audio amplifier Power supply For Behringer Developed at the University of Oviedo (GEI group) 11/11/2003 Advanced Techniques in Power Factor Correction 108 Using only a RE (XX) Experimental results: line waveforms Resistor Emulator based on a 300 W boost converter 0.5 A/div 5ms/div 0.5 A/div 5ms/div AR = 10 AR = 10 Simulated Result fC = 10 Hz 0.5 A/div 5ms/div Simulated Result 11/11/2003 fC = 1 kHz Simulated Result 0.5 A/div 5ms/div AR = 25 fC = 1 kHz Simulated Result Advanced Techniques in Power Factor Correction AR = 40 fC = 1 kHz 109 Using only a RE (XXI) Experimental results: transient response fC = 10 Hz 60 ms Full load 1/3 Full load fC = 1kHz 1/3 Full load 11/11/2003 10 ms Advanced Techniques in Power Factor Correction Full load 110 Using only a RE (XXII) Conclusions of the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications (I) Many applications do not need fast dynamic response. In these cases conventional Resistor Emulators (like flyback) can be used directly as power supply with no second stage and with several advantages: Low cost and size (no second stage) Very low harmonic content Can be used in high and low power applications. Can be used with universal line voltage 11/11/2003 Advanced Techniques in Power Factor Correction 111 Using only a RE (XXIII) Conclusions of the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications (II) The limitations in the transient response are: The 100-120 Hz output voltage ripple only depends on the capacitor value This ripple ripple cannot be reduced by increasing the corner frequency of the output-voltage feedback loop The maximum effective corner frequency is about 1kHz (10 times the ripple frequency) The minimum response time is 10-8.3 ms (one 100-120 Hz cycle) 11/11/2003 Advanced Techniques in Power Factor Correction 112 Using only a RE (XXIV) Conclusions of the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications (III) This solution should not be used if the output voltage is relatively low (lower than 12 V) due to the fact that the bulk capacitor is placed just at the output, which means: Energy stored at low voltage Large value of the capacitor size High current levels passing through the capacitor Large capacitor losses due to the ESR 11/11/2003 Advanced Techniques in Power Factor Correction 113 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 114 High-efficiency post-regulators (I) Line curent fp: 1000 Hz Can we improve the dynamic response of a Resistor Emulator with a low penalty in the converter efficiency? Output voltage fp: 10 Hz Time (ms) DC/DC converter 10 90 ms 10 ms 60 40 20 40 60 80 100 120 Time (ms) 20 AR 0 AR [dB] -20 -40 45 Lowpass filter 0 -45 -90 -135 The minimum response time is 10-8.3 ms (one 100-120 Hz cycle) AR [º] 1 10 100 fp 11/11/2003 1000 fp 10000 f [Hz] Another stage can be connected to improve the transient response Advanced Techniques in Power Factor Correction 115 High-efficiency post-regulators (II) DC/DC converter Line Lowpass filter Characteristic of the high-efficiency post regulators High+ efficiency + V1 postVO Output - regulators - Common characteristics of all highefficiency post-regulators: Low additional cost and size Only a fraction of the total power undergoes a power switching processing Very high efficiency: 96-98% No short-circuit protection in the postregulator V 11/11/2003 1 and VO are voltages of similar values Advanced Techniques in Power Factor Correction 116 High-efficiency post-regulators (III) Use of the high-efficiency post regulators in multiple-output applications High+ efficiency + V1 postVO Output - regulators - Line fp: 10 Hz fp: 1000 Hz fp: 10 Hz Lowpass filter 90 ms 10 ms fp: 1000 Hz Some slow or medium-speed outputs and some fast response outputs 11/11/2003 Advanced Techniques in Power Factor Correction 117 High-efficiency post-regulators (IV) DC/DC converter Line Operation principle of the highefficiency post regulators - VS + V1 - + + VO Output - High-efficiency post-regulators Lowpass filter vS vO How can we implement the voltage source? v1 Time 11/11/2003 Advanced Techniques in Power Factor Correction 118 Implementing the voltage source VS (I) High-efficiency post-regulators (V) Where should we connect the input port of this converter? ? Small DC/DC converter DC/DC converter Line + V1 - - VS + + VO Output - High-efficiency post-regulators Lowpass filter 11/11/2003 Advanced Techniques in Power Factor Correction 119 Implementing the voltage source VS (II) High-efficiency post-regulators (VI) One additional output Small DC/DC converter DC/DC converter - VS + + V1 - Line + VO Output - High-efficiency post-regulators Lowpass filter Option #1: connect the input port to an additional Resistor Emulator output 11/11/2003 Advanced Techniques in Power Factor Correction 120 Implementing the voltage source VS (III) High-efficiency post-regulators (VII) Small DC/DC converter DC/DC converter Line + V1 - - VS + + VO Output - High-efficiency post-regulators Lowpass filter 11/11/2003 Option #2: connect the input port to the Resistor Emulator output Advanced Techniques in Power Factor Correction 121 Implementing the voltage source VS (IV) High-efficiency post-regulators (VIII) Small DC/DC converter Small DC/DC converter V2 - VS + - VS + + + V1 VO V1 VO - - - - + High-efficiency postregulators High-efficiency post-regulators Option #1: connect the input port to an additional output of the Resistor Emulator Option #2: connect the input port to the Resistor Emulator output Two-Input Buck (TIBuck) Series-Switching postRegulator (SSPR) 11/11/2003 + Advanced Techniques in Power Factor Correction 122 High-efficiency post-regulators (IX) Why is the efficiency of these postregulators very high? Small DC/DC converter DC/DC converter + V1 - vS IO - VS + + VO - High-efficiency post-regulators Lowpass filter v1 Time V1, VO >> VS P1, PO >> PS The “Small DC/DC converter” is processing only a small part of the output power Low losses in the post-regulator High efficiency post-regulator 11/11/2003 vO Advanced Techniques in Power Factor Correction 123 High-efficiency post-regulators (X) Why is not possible to implement a over-load or short-circuit protection in these post-regulators? Small DC/DC converter DC/DC converter + V1 - IO - VS + 0 High-efficiency post-regulators Lowpass filter 11/11/2003 + VO - A over-load occurs If VS = 0, then VO = V1 0 The over-load or short-circuit protection must be implemented in the Resistor Emulator Advanced Techniques in Power Factor Correction 124 High-efficiency post-regulators (XI) Introducing the Two-Input Buck (TIBuck) Small DC/DC converter V2 + - VS + + V1 VO - High-efficiency post-regulators DC/DC converter V2 + VS - This is a Buck converter with two inputs instead of one VO + V1 - High-efficiency post-regulators 11/11/2003 Advanced Techniques in Power Factor Correction + 125 High-efficiency post-regulators (XII) Single-output Resistor Emulator based on a Flyback + a TIBuck post-regulator V2 + VO + V1 - Standard controller Resistor Emulator controller 11/11/2003 TIBuck post-regulators Advanced Techniques in Power Factor Correction 126 High-efficiency post-regulators (XIII) Multiple-output Resistor Emulator based on a Flyback + a TIBuck post-regulator V4 + V2 + VO + V1 - + V3 - Standard controller TIBuck post-regulators Resistor Emulator controller 11/11/2003 Advanced Techniques in Power Factor Correction 127 High-efficiency post-regulators (XIV) + VQ Comparing Buck and TIBuck converters + VO VD V1 VDMAX = V1 VO = V1d Buck + V1 > VO VQMAX = V1 (d is the duty cycle) - VQ + V2 VD VO V1 V2 > VO > V1 VQMAX = V2-V1 VDMAX = V2-V1 VO = V2d + V1(1-d) (from volts-second balance) TIBuck 11/11/2003 Advanced Techniques in Power Factor Correction 128 High-efficiency post-regulators (XV) DC equivalent circuit for the TIBuck VO= V2d + V1(1-d) = (V2-V1)d + V1 (V2-V1)d Controlled VO Poorly regulated V1 PWM 11/11/2003 Regulated Advanced Techniques in Power Factor Correction + 129 High-efficiency post-regulators (XVI) Relationship between input and output voltages (I) + Voltages V2 range VQ + V2 VO V1 range VO VD V1 Time - PWM + ALWAYS V2 > VO > V1 11/11/2003 Advanced Techniques in Power Factor Correction 130 High-efficiency post-regulators (XVII) Relationship between input and output voltages (II) Case of being used as post-regulator of a Resistor Emulator Voltages v2 V2 VO Transient response Steady state v1 + VO + V1 - - Time ALWAYS V2 > VO > V1, taking into account the worse case of transient response and ripple 11/11/2003 Advanced Techniques in Power Factor Correction 131 High-efficiency post-regulators (XVIII) Comparing filter inductance for Buck and TIBuck converters (I) LB VFilter VO + V1 VFilter Buck V1 VO Time LTB + VFilter VO V2 TIBuck 11/11/2003 VO V1 VFilter V1 V2 Time Lower value in the case of the TIBuck converter (in practice, 3 times lower) Advanced Techniques in Power Factor Correction 132 High-efficiency post-regulators (XIX) Comparing filter inductance for Buck and TIBuck converters (II) Boundary between continuous and discontinuous conduction modes • CCM: 2L/RT > KCRIT • DCM: 2L/RT < KCRIT KCRIT 1 Buck Buck: K CRIT (1 - d) TIBuck V2 / V1=4 d(1- d)(V2 /V1 - 1) TIBuck: KCRIT d(V2 /V1 - 1) 1 3 2 1.25 Lower value in the case of the TIBuck converter 0 0 1 d (duty cycle) 11/11/2003 Advanced Techniques in Power Factor Correction 133 High-efficiency post-regulators (XX) Explaining the high efficiency of the TIBuck converter (I) Realistic case for a Buck converter: VG = 100 V IG = 1 A PG = 100 W VG Buck R VOB VOB = 50 V IO = 1.8 A POB = 90 W d = 0.55 PLosses = 10 W R = VOB/IO = 27.8 W = 90 / 100 = 90% 11/11/2003 Advanced Techniques in Power Factor Correction 134 High-efficiency post-regulators (XXI) Explaining the high efficiency of the TIBuck converter (II) d = 0.55 PLosses = 10 W VG = 100 V IG = 1 A PG = 100 W V1 = 300 V V1 IO = 1.8 A P1 = 540 W VG IO VOB VOB = 50 V IO = 1.8 A POB = 90 W Buck IO R1 IO = 1.8 A V1 = 300 V P1 = 540 W IO = 1.8 A R1 = V1/IO = 166.7 W We are processing 540 W FREE !! = (90 + 540) / (100 + 540) = 98.4 % 11/11/2003 Advanced Techniques in Power Factor Correction 135 High-efficiency post-regulators (XXII) VG = 100 V IG = 1 A PG = 100 W 27.8 W d = 0.5 166.7 W IO = 1.8 A V1 = 300 V P1 = 540 W I2 I2 = IG = 1 A I1 = IO- IG = 0.8 A V2 = VG+ V1= 400 V P2 = 400 W P1 = 240 W Pi = P2 + P1 =640 Explaining the high efficiency of the TIBuck converter (III) VOB = 50 V IO = 1.8 A POB = 90 W IO = 1.8 A V1 = 300 V P1 = 540 W d = 0.5 194.5 W V2 I1 IO = 1.8 A VO = VOB+ V1= 350 V PO = POB+ P1= 630 W V1 = 630 / 640 = 98.4% 11/11/2003 Advanced Techniques in Power Factor Correction 136 High-efficiency post-regulators (XXIII) VO Explaining the high efficiency of the TIBuck converter (IV) VO-V1 V2 – V1 V2 V1 V1 V1 VO-V1 V2 – V1 V1 V1 VO-V1 V2 – V1 V1 11/11/2003 V1 The closer V2 and V1 (and, therefore VO) the higher the efficiency Advanced Techniques in Power Factor Correction 137 High-efficiency post-regulators (XXIV) Explaining the high efficiency of the TIBuck converter (V) B is the Buck-part efficiency VO-V1 TB V2 – V1 V1 TB=1 B V1 1- (1- B ) VO V1 TB is the TIBuck efficiency TIbuck efficiency 100 TB=96.6% High efficiency TIbuck with a limited efficiency in the Buck part 80 60 90% 85% 75% B =50% 0.4 0.6 0.8 V1/VO 11/11/2003 Advanced Techniques in Power Factor Correction 138 1 High-efficiency post-regulators (XXV) LTB The quantities with hats are the perturbations d̂ v̂ 2 V2 V1 VO CTB R V2-V1 D + + + v̂ 1 Small-signal transfer functions of the TIBuck converter 1- D 1 CTBL TBs2 L TB s1 R v̂ O Output filter Similar to the case of a Buck converter, but faster due to the lower values of the output filter components 11/11/2003 Advanced Techniques in Power Factor Correction 139 High-efficiency post-regulators (XXVI) Implementing the transistor driver Requirements: Galvanic isolation Wide duty cycle operation 11/11/2003 Advanced Techniques in Power Factor Correction 140 High-efficiency post-regulators (XXVII) Experimental results of TIBuck-based prototypes (I) TIBuck DC/DC post-regulators V2 V1 VO IO LTB CTB fS TIBuck 1 440-400 V 360-320 V 380 V 1-0.1 A 1 mH 250 nF 100 kHz TIBuck 2 67-57 V 52-42 V 54.5 V 4-0.4 A 51.4 mH 4.7 mF 100 kHz 11/11/2003 Advanced Techniques in Power Factor Correction 141 High-efficiency post-regulators (XXVIII) TIBuck 1: overall efficiency Experimental results of TIBuck-based prototypes (II) Efficiency [%] 100 V2=440V V1=360V 99 V2=420V V1=340V V2=400V V1=320V 98 100 200 300 Output power [W] 11/11/2003 Advanced Techniques in Power Factor Correction 142 High-efficiency post-regulators (XXIX) Experimental results of TIBuck-based prototypes (III) TIBuck 1 efficiency with V2 & V1 variable, V2-V1 =80 V, VO=(V1+V2)/2 V2 VO Efficiency [%] 100 380,300,340 280,200 240 95 V1 V2 = 80 V V1 = 0 V VO = 40 V 90 Being V2-V1 a constant, the closer V2 and V1 (and, therefore VO) the higher the efficiency 11/11/2003 85 V2 = 180 V V1 = 100 V VO = 140 V 0 500 100 0 Output current [mA] Advanced Techniques in Power Factor Correction 143 High-efficiency post-regulators (XXX) Experimental results of TIBuck-based prototypes (IV) TIBuck 1 and Buck-part efficiencies Efficiency [%] B is the Buck-part efficiency 100 TIBuck TIBuck (measured) (calculated) VO-V1 V2 – V1 90 V1 =1 V1 TB is the TIBuck efficiency TB Buck-part (measured) B V1 1- (1- B ) VO 80 70 200 400 600 Output current [mA)] The experimental results fit very well with the calculated ones 11/11/2003 Advanced Techniques in Power Factor Correction 144 High-efficiency post-regulators (XXXI) Experimental results of TIBuck-based prototypes (V) TIBuck 2: overall efficiency and small-signal modelling Gain [dB] , phase Efficiency [%] 40 100 Theoretical 0º 96 20 Measured -90 92 0 0 100 Theoretical -180º 200 Output power [W] -20 100 1,000 10,000 Frequency [Hz] 11/11/2003 Advanced Techniques in Power Factor Correction 145 High-efficiency post-regulators (XXXII) Resistor Emulator based on a Flyback converter + TIBuck 2 Experimental results of TIBuck-based prototypes (VI) 25CPF40 3t 24 t 85-264V IRF7403 51.4mH 10 T045 1.5mF 54V 4A 4.7mF 9t 1.5mF IRFPC50 UC3825 Overall efficiency [%] UC3854 Transient response VO V2 5V/div 1V/div 88 IO 86 0.01A/ms 2.1A 3.23A 200 ms/div 11/11/2003 220V Advanced Techniques in Power Factor Correction 110V 84 80 120 160 200 Output power [W] 146 High-efficiency post-regulators (XXXIII) Experimental results of TIBuck-based prototypes (VII) Voltage ripple cancellation in the case of the Resistor Emulator based on a Flyback converter + TIBuck 2 V2 V1 IRF7403 51.4mH 10T045 4.7mF Voltage ripples V2 2V/div. + VO VO 0.5V/div. UC3825 V1 2V/div. Voltage-Mode control Can we improve the ripple cancellation? 11/11/2003 Advanced Techniques in Power Factor Correction 147 High-efficiency post-regulators (XXXIV) Experimental results of TIBuck-based prototypes (VIII) Other TIBuck control methods to improve the voltage ripple cancellation Input voltage feedforward Current mode control (average current mode control) Input voltage feedforward V2 IRF7403 V1 51.4mH + 10T045 4.7mF UC3825 Feedforward 11/11/2003 VO - + V1 + V2 + V dc R1 R Rext Cext 2 vC UC3825 Feedforward implementation Advanced Techniques in Power Factor Correction 148 High-efficiency post-regulators (XXXV) Experimental results of TIBuck-based prototypes (IX) Voltage ripples Average current mode control V2 2V/div. V2 IRF7403 51.4mH + 10T045 V1 VO 2mV/div. VO 4.7mF - V1 2V/div. Transient response UC3825 TL082 V2 (5 V/div) Voltage ripple attenuation 66dB (1900 times). Also, excellent transient response IO VO (20 mV/div) 0.01A/ms 2.1A 3.23A 100 ms/div 11/11/2003 Advanced Techniques in Power Factor Correction 149 High-efficiency post-regulators (XXXVI) Introducing the option #2: SeriesSwitching Post-Regulator (SSPR) Small DC/DC converter + - VS + Small DC/DC converter + V1 VO - - + - VS + + V1 VO - - High-efficiency postregulators Re-drawing Option #2: connect the input port to the Resistor Emulator output VS + + + Series-Switching postRegulator (SSPR) 11/11/2003 V1 - Small DC/DC converter VO Advanced Techniques in Power Factor Correction 150 High-efficiency post-regulators (XXXVII) + V1 Small DC/DC converter - Introducing the SSPR based on a Forward converter VS + + VO - + Re-placing the capacitor V1 + Small DC/DC converter - VO - Controller + V1 Small DC/DC converter - VS + + VO 11/11/2003 The controlled output voltage is VO instead of VS Advanced Techniques in Power Factor Correction 151 High-efficiency post-regulators (XXXVIII) Other SSPR implementations Implementation based on a Flyback n1 + V1 + Small DC/DC converter - Small DC/DC converter n2 VO + - VS + + V1 VO - - Controller If n1=n2 The implementation based on a Flyback becomes a Boost converter if n1=n2 A Boost converter has a very high efficiency if the input and output voltages are very close 11/11/2003 + V1 + - VO Advanced Techniques in Power Factor Correction - Controller 152 High-efficiency post-regulators (XXXIX) Single-output Resistor Emulator based on a Flyback + a Forward-type SSPR + + V1 VO Resistor Emulator controller 11/11/2003 Standard controller Forward-type SSPR Advanced Techniques in Power Factor Correction 153 High-efficiency post-regulators (XL) Multiple-output Resistor Emulator based on a Flyback + a Forward-type SSPR V3 + + + V1 VO + V2 - Standard controller Forward-type SSPR Resistor Emulator controller 11/11/2003 Advanced Techniques in Power Factor Correction 154 High-efficiency post-regulators (XLI) I1 + V1 Computing SSPRs efficiency (I) IO IiDC - VS + + Small DC/DC converter VO C SSPR ss PWM IO + VO = V1 + VS I1 = IiDC + IO C = VS·IO VO·IO 1+KS SS = = KS V1·I1 1+ C Being KS=VS/V1 V1·IiDC 11/11/2003 Advanced Techniques in Power Factor Correction 155 High-efficiency post-regulators (XLII) SS [%] Example: 100 95 0.2 Computing SSPRs efficiency (II) C = 80% 0.1 KS = VS/V1 = 0.1 ss = 97.7% 90 85 KS=0.3 The lower KS, the higher the efficiency KS=VS/V1 80 60 70 80 c [%] 90 Voltages 100 vO vS However, VS must reaches VSmax and must be always positive v1 vSmax Steady state Transient response Time 11/11/2003 Advanced Techniques in Power Factor Correction 156 High-efficiency post-regulators (XLIII) Experimental results of a Forward-type SSPR (I) 11DQ10 E20 12CTQ045 + 47mH, E20 V1 = 47V 28 : 28 : 15 6,800mF SMP20N20 - fS = 100 kHz 47mF VS = 7.5V + + VO= 54.5 V IO = 4 A - Efficiency [%] 98 97 96 95 11/11/2003 Output power [W] 0 50 100 150 Advanced Techniques in Power Factor Correction 200 250 157 High-efficiency post-regulators (XLIV) Average current mode control Experimental results of a Forward-type SSPR (II) Voltage ripples V1 (1V/div) + VO (10mV/div) + V1 VO - 10 ms/div UC3825 TL082 (Attenuation 50dB) Transient response V1 (5V/div) IO 0.01A/ms 1.83A 3.67A VO (20mV/div) 200 ms/div 11/11/2003 Advanced Techniques in Power Factor Correction 158 High-efficiency post-regulators (XLV) Conclusions of the use of Highefficiency post-regulators to improve the transient response of Resistors Emulators (I) Low additional cost and size Low output voltage ripple and fast dynamic response Very high post-regulator efficiency (96-98%) Very low harmonic content Can be used in high and low power applications Can be used with universal line voltage Very interesting for multiple-output applications with different transient response specifications 11/11/2003 Advanced Techniques in Power Factor Correction 159 High-efficiency post-regulators (XLVI) Conclusions of the use of Highefficiency post-regulators to improve the transient response of Resistors Emulators (II) V and V are voltages of similar values It is not a good solution for low output voltage applications 1 O because the energy is stored near the output voltage No short-circuit and/or overload protection can be implemented in the post-regulator (it must be implemented in the Resistor Emulator) However, short-circuit overcurrent from the bulk capacitor can be diverted through an additional diode (see next slide) 11/11/2003 Advanced Techniques in Power Factor Correction 160 High-efficiency post-regulators (XLVII) Small DC/DC converter + V1 - - VS + Additional diode to divert shortcircuit overcurrent from the bulk capacitor The overcurrent is diverted by the diode Da + Da VO overcurrent - V2 CB2 High-efficiency post-regulators + - + Da + V1 VO - - The drive pulses must be eliminated 11/11/2003 + Da VO V1 CB1 - The drive pulses must be maintained to discharge CB2 CB1is discharged through the additional diode Da Advanced Techniques in Power Factor Correction 161 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 162 Single–Stage PFCs (I) Standard Two-Stage approach (I) • High voltage • Almost-constant voltage Low bulk capacitor size DC Bus Current Line Resistor Emulator Conventional (Boost converter) converter Current Feedback-Loop DC/DC Voltage Feedback-Loop 2 11/11/2003 Advanced Techniques in Power Factor Correction Load - Voltage Feedback-Loop 1 163 Single–Stage PFCs (II) Standard Two-Stage approach (II) DC Bus Current Line Resistor Emulator Conventional (Boost converter) converter DC/DC - Current Feedback-Loop Voltage Feedback-Loop 2 Compliance with IEC 1000-3-2 Fast output voltage response DC bus regulated (interesting for 85-264V ac ) 11/11/2003 Load Voltage Feedback-Loop 1 - Expensive Low efficiency? Not for universal line Advanced Techniques in Power Factor Correction 164 Single–Stage PFCs (III) Introducing Single-Stage PFCs (I) DC Bus Current Resistor Emulator Line Current Feedback-Loop Conventional DC/DC (Boost converter) Load converter Voltage Feedback-Loop 2 Voltage Feedback-Loop 1 - Single-Stage DC Bus Current 11/11/2003 Line Load PFC Voltage Feedback-Loop Advanced Techniques in Power Factor Correction 165 Single–Stage PFCs (IV) Introducing Single-Stage PFCs (II) Single-Stage DC Bus Current Line Compliance with IEC 1000-3-2 Fast output voltage response Cheap Energy stored at high voltage 11/11/2003 Load PFC Voltage Feedback-Loop - DC bus unregulated (not very interesting for 85-264 V) Advanced Techniques in Power Factor Correction 166 Single–Stage PFCs (V) Introducing Single-Stage PFCs (III) ZS Current Previous methods to increase the conduction angle DC/DC Line converter Simple passive components R Line DC/DC converter A resistor L Line DC/DC converter 11/11/2003 Advanced Techniques in Power Factor Correction An inductor 167 Introducing Single-Stage PFCs (IV) Single–Stage PFCs (VI) ZS Current DC/DC Line converter Could we find a small-size lossless impedance ZS? Lossless Based on inductors Small size Working at the switching frequency Small size nly diodes (no transistors) It is an additional output DC/DC Line converter Current 11/11/2003 Advanced Techniques in Power Factor Correction 168 Single–Stage PFCs (VII) Equivalent circuit for many S2PFC Introducing Single-Stage PFCs (V) + - HIAN Magnetic device Current Load Conventional Line Bulk capacitor DC/DC converter HIAN: High Impedance Active Network 11/11/2003 Advanced Techniques in Power Factor Correction 169 Single–Stage PFCs (VIII) Example of topological transformations (I) HIAN DCM DC/DC converter HIAN DCM DC/DC Converter 11/11/2003 Advanced Techniques in Power Factor Correction 170 Single–Stage PFCs (IX) DCM Example of topological transformations (II) nS n1 nS n2 n1 n2 DCM nS’ = n1-nS nS’ DCM 11/11/2003 n2 n1 Advanced Techniques in Power Factor Correction Presented at INTELEC 96 by F. S. Tsai, P. Markowski & E. Whitcomb 171 Single–Stage PFCs (X) Example of topological transformations (III) nS n1 n2 DCM nS = n1 nS=n1 n2 DCM Presented at PESC 94 by R. Redl, L. Balog and N. Sokal 11/11/2003 Advanced Techniques in Power Factor Correction 172 Single–Stage PFCs (XI) Examples of HIAN (I) LF in DCM LF in CCM + + - - #1. One inductor (in DCM) Only 1 inductor Either high current or voltage stress (it will be explained later) Ld #2. Two inductors Low current and + - voltage stress 2 inductors HIAN DC/DC converter 11/11/2003 Advanced Techniques in Power Factor Correction 173 Single–Stage PFCs (XII) Examples of HIAN (II) LF in CCM Ld One inductor (in DCM) + LF in DCM - + Ld1 LF in CCM Two inductors - + - LF in DCM Ld2 + LF in CCM - + - 11/11/2003 Advanced Techniques in Power Factor Correction Ld 174 Single–Stage PFCs (XIII) HIAN IHIAN - Generalization + VHIAN Rectifier Conventional DC/DC Filter inductor converter IHIAN Delaying inductor LF Ld + VHIAN HIAN 11/11/2003 Advanced Techniques in Power Factor Correction 175 Cases to study: 1st) only LF and in DCM (DCM1) Single–Stage PFCs (XIV) HIAN IHIAN IHIAN LF + - VHIAN + VHIAN - Conventional DC/DC converter nS (a) IHIAN LF + nS VHIAN Design parameters: • Ld = 0 • LF in DCM • n1/nS n1 IHIAN (b) LF + VHIAN - nS nS 11/11/2003 n1 Advanced Techniques in Power Factor Correction n1 (c) 176 Cases to study: 2nd) two inductors, LF in CCM Single–Stage PFCs (XV) HIAN IHIAN - IHIAN LF + + VHIAN Ld Conventional DC/DC VHIAN nS IHIAN converter n1 (d) LF Ld + nS VHIAN Design parameters: - • Ld IHIAN • K = LF/Ld + • n1/nS - 11/11/2003 VHIAN (e) LF Ld nS nS Advanced Techniques in Power Factor Correction n1 n1 (f) 177 Cases to study: 3rd) only Ld (DCM2) Single–Stage PFCs (XVI) HIAN IHIAN IHIAN Ld + VHIAN - + VHIAN nS Conventional (g) IHIAN DC/DC converter n1 Ld + nS VHIAN n1 Design parameters: • LF = 0 • Ld IHIAN Ld1 + VHIAN nS Ld2 • n1/nS 11/11/2003 (h) Advanced Techniques in Power Factor Correction nS n1 (i) 178 Cases to study: Two more HIANs Single–Stage PFCs (XVII) From: IHIAN 4·Ld , IHIAN/2 4·Ld , IHIAN/2 IHIAN + + VHIAN VHIAN - - (e’) (h’) similar to similar to IHIAN IHIAN Ld , IHIAN Ld , IHIAN + + VHIAN VHIAN 11/11/2003 (e) - Advanced Techniques in Power Factor Correction (h) 179 Focusing the analysis (I): Single–Stage PFCs (XVIII) HIAN IHIAN ig(wt) - + VHIAN Vg(wt) Conventional VC DC/DC converter We need: •To choose the HIAN according the application requirements • To calculate the value of the inductor(s) in order to have a line current harmonic content below the values specified in the IEC 61000-3-2 How can we establish a relationship between the HIAN and the line current harmonic content? Equations: VHIAN = Vc - |Vg(wt)| IHIAN = f(VHIAN) This is the Voltage-Current Characteristic, VCC ig(wt) = IHIAN if Vg(wt) > 0 and ig(wt) = -IHIAN if Vg(wt) < 0 11/11/2003 Advanced Techniques in Power Factor Correction 180 Focusing the analysis (II): Single–Stage PFCs (XIX) Therefore: we need to determine the Voltage-Current Characteristic, VCC, for each HIAN IHIAN = f(VHIAN) IHIN HIAN - + VHIAN Conventional VC DC/DC converter Considerations for the study: Vc and the converter duty cycle “d” considered constant each line half-cycle 11/11/2003 Advanced Techniques in Power Factor Correction 181 Previous design considerations (I) Single–Stage PFCs (XX) The variation of Vc should be as low as possible VHIAN(IHIAN average max) as low as possible HIAN with Ld. VHIAN(IHIAN average max) IHIAN average IHIAN LF + + Ld=0 VHIAN - Ld VHIAN Ld0 - (a) VHIAN LF nS n1 (b) 11/11/2003 IHIANLF LF nS nS Advanced Techniques in Power Factor Correction n1 (c) The case Ld=0 is not desirable (cases a, b and c) 182 Previous design considerations (II) Single–Stage PFCs (XXI) The current stress in the DC/DC converter should be as low as possible LF in DCM LF in DCM nS nS n1 n1 (b) (a) For this reason, the case Ld=0 is not desirable again (cases a, b and c) LF in DCM LF nS nS 11/11/2003 n1 (c) The total inductor size should be as small as possible Advanced Techniques in Power Factor Correction 183 Voltage-Current Characteristics (calculated from IHIAN average) Single–Stage PFCs (XXII) IHIAN LF>>Ld Ld Results after solving the operation equations: + VHIAN - 20 IHIAN average Case e IHIAN LF<<Ld 15 Ld + 10 VHIAN - Case e IHIAN + 11/11/2003 5 LF<<Ld Ld LF=0 0 VHIAN - LF>>Ld 0 20 40 60 80 100 VHIAN Case h Advanced Techniques in Power Factor Correction 184 Input current waveforms (examples) obtained from the previous VoltageCurrent Characteristics Single–Stage PFCs (XXIII) Voltage-Current Characteristics IHIAN average Line waveforms IHIAN average 20 20 15 15 LF>>Ld LF>>Ld 10 10 5 LF<<Ld LF=0 0 0 20 40 60 80 LF<<Ld 5 LF=0 100 VHIAN 0 0 30 60 90 120 150 180 line angle IHIAN depends on VHIAN , LF , Ld and also on d, n1/nS and VC 11/11/2003 Advanced Techniques in Power Factor Correction 185 Comparing Voltage-Current Characteristics calculated from IHIAN average and from IHIAN peak Single–Stage PFCs (XXIV) IHIAN IHIAN 20 20 LF=0 LF=0 15 IHIAN peak 10 IHIAN average IHIAN peak 15 IHIAN average 10 5 5 0 20 0 40 60 80 100 VHIAN 0 0 30 60 90 120 150 180 line angle VCCaverage: to determine low-frequency harmonics VCCpeak: to determine size of magnetics and component stress 11/11/2003 Advanced Techniques in Power Factor Correction 186 Single–Stage PFCs (XXV) Examples of VCCaverage and VCCpeak for different HIAN The values of Vc, d, n1/nS and Ld are the same for all the examples K = LF/Ld LF Ld K=0 + K = 0.1 K=1 K = 10 IHIAN peak VHIAN IHIAN average LF Ld + K=0 K = 0.1 K=0 K = 0.1 K=1 K = 10 VHIAN Ld LF + VHIAN K=1 K = 10 - Ld 11/11/2003 Advanced Techniques in Power Factor Correction 187 Single–Stage PFCs (XXVI) Conclusions from the previous examples (I) Higher K values have no effect in IHIAN peak K = LF/Ld LF Ld K=0 + K = 0.1 K=1 K = 10 IHIAN peak VHIAN IHIAN average LF Ld + K=0 K = 0.1 K=0 K = 0.1 K=1 K = 10 VHIAN LF Ld + VHIAN K=1 K = 10 - Ld 11/11/2003 Advanced Techniques in Power Factor Correction 188 Single–Stage PFCs (XXVII) Conclusions from the previous examples (II) Due to the same reason, LF is not necessary K = LF/Ld LF Ld K=0 + K = 0.1 K=1 K = 10 IHIAN peak VHIAN IHIAN average LF Ld + K=0 K = 0.1 K=0 K = 0.1 K=1 K = 10 VHIAN Ld LF + VHIAN K=1 K = 10 - Ld 11/11/2003 Advanced Techniques in Power Factor Correction 189 Single–Stage PFCs (XXVIII) Higher impedance in the case of full-wave rectifier lower Ld values for the same impedance K = LF/Ld LF Conclusions from the previous examples (III) Ld K=0 + K = 0.1 K=1 K = 10 IHIAN peak VHIAN IHIAN average LF Ld + K=0 K = 0.1 K=0 K = 0.1 K=1 K = 10 VHIAN LF Ld + VHIAN K=1 K = 10 - Ld 11/11/2003 Advanced Techniques in Power Factor Correction 190 Single–Stage PFCs (XXIX) Optimum design of an example Flyback as DC/DC converter Pout = 100 W Vout = 54 V European AC voltage (190-265) IEC 61000-3-2, Class D Maximum duty = 0.35 33 W as limit between CCM and DCM Switching frequency = 100 kHz 11/11/2003 Advanced Techniques in Power Factor Correction 191 Single–Stage PFCs (XXX) Total size of magnetic elements for the previous example K=LF/Ld LF Ld (d) LF Ld (e) LF (f) Ld Ld K=0 K=0.1 K=0.5 K=1 K=2 K=10 Ld (mH) 70 542 268 268 291 353 LF (mH) 0 54.2 134 268 582 3530 SIx2·Lx (mJ) 943 1488 1003 1338 2179 9693 Ld (mH) 47.8 221 76.5 105.7 87.2 92.7 LF (mH) 0 22.1 38.25 105.7 174.4 927 SIx2·Lx (mJ) 424.5 770.2 440.8 603.7 773.9 2676 Ld (mH) 185.2 167 174.4 178.7 182.5 167.1 LF (mH) 0 16.7 87.2 178.7 365 1671 SIx2·Lx (mJ) 1107 1086 1213 1424 1845 5133 GOOD 11/11/2003 Advanced Techniques in Power Factor Correction GOOD 192 Single–Stage PFCs (XXXI) LF Ld (d) LF Ld (e) LF (f) Ld Ld Voltage and current stress for the previous example K=LF/Ld 0 0.1 0.5 1 2 10 VC_max (V) 423 540 425 413 415 415 IS_peak (A) 2.53 3.14 2.48 2.41 2.39 2.42 VC_max (V) 437 560 420 420 414 416 IS_peak (A) 2.24 2.7 2 2 1.97 1.93 VC_max (V) 420 415 418 419 418 420 IS_peak (A) 2 1.98 1.95 1.94 1.93 1.89 GOOD 11/11/2003 Advanced Techniques in Power Factor Correction GOOD 193 Summary of “good” designs for the previous example (I) Single–Stage PFCs (XXXII) Flyback as DC/DC converter Pout = 100W Vout = 54V European AC voltage (190-265) IEC 61000-3-2, Class D Maximum duty 0.35 33 W as limit between CCM and DCM Switching frequency 100kHz LF + VHIAN - Ld nS n1 K=LF/Ld 0.5 1 n1/nS 1.813 1.875 VC_max (V) 425 413 Ld (mH) 268 268 LF (mH) 134 268 SIx2·Lx (mJ) 1003 1338 Interesting for Forward DC/DC converters 11/11/2003 Advanced Techniques in Power Factor Correction 194 Summary of “good” designs for the previous example (II) Single–Stage PFCs (XXXIII) Flyback as DC/DC converter Pout = 100W Vout = 54V European AC voltage (190-265) IEC 61000-3-2, Class D Maximum duty 0.35 33 W as limit between CCM and DCM Switching frequency 100kHz K=LF/Ld 0.5 1 n1/nS 3.125 2.625 VC_max (V) 420 420 Ld (mH) 76.5 105.7 LF (mH) 38.25 105.7 SIx2·Lx (mJ) 440.8 603.7 LF Ld + VHIAN nS n1 LF 4·Ld + VHIAN - nS nS n1 Interesting for all DC/DC converters, except Forward 11/11/2003 Advanced Techniques in Power Factor Correction 195 Summary of “good” designs for the previous example (III) Single–Stage PFCs (XXXIV) Flyback as DC/DC converter Pout = 100W Vout = 54V European AC voltage (190-265) IEC 61000-3-2, Class D Maximum duty 0.35 33 W as limit between CCM and DCM Switching frequency 100kHz Ld + VHIAN - nS nS n1 Ld K=LF/Ld 0 n1/nS 2.875 VC_max (V) 420 Ld (mH) 185.2 SIx2·Lx (mJ) 1107 Interesting for all DC/DC converters, except Forward 11/11/2003 Advanced Techniques in Power Factor Correction 196 Analysing the high-frequency harmonics Single–Stage PFCs (XXXV) Full-wave HIANs are better than the half-wave one Comparing full-wave HIANs: High-frequency ripple at /2 (A) LF K=0 Ld + Better VHIAN 0.2 - LF Ld + K=0.5 VHIAN Ld 0.1 The HIAN type “e” is the most interesting from this point of view 11/11/2003 K=0 K=1 K=2 500 1000 K=0.5 K=1 1500 K=2 2000 SIx2·Lx (mJ) Advanced Techniques in Power Factor Correction 197 Single–Stage PFCs (XXXVI) The lossless resistor model (I) HIAN IHIAN - + VHIAN Conventional DC/DC converter Is there any simple model for the HIAN? Yes, if LF >>Ld 11/11/2003 Advanced Techniques in Power Factor Correction 198 Single–Stage PFCs (XXXVII) If LF >>Ld (small line current ripple) Vi1 The lossless resistor model (II) IHIAN + Vi VHIAN - D1 LF + D2 ILd + Vi Ld VD2 - VD2 VHIAN = Vi1·(d – fS·td) = IHIAN Vi1·(d – fS·Ld·IHIAN/Vi1) = Vi1·d – fS·Ld·IHIAN ILd VHIAN = VS – RLF·iHIAN td t=d/fS 11/11/2003 iHIAN 1/fS Advanced Techniques in Power Factor Correction VHIAN + 199 Single–Stage PFCs (XXXVIII) LF The lossless resistor model (III) Ld If LF>>Ld VS Loss-free resistor RLF = Ld·fs DC/DC DC/DC converter converter Input current After analysing the circuit using this model: Compliance at 220V: C>67.5º C 11/11/2003 Compliance at 230V: C>64.5º (in Class D) Advanced Techniques in Power Factor Correction 200 Single–Stage PFCs (XXXIX) IHIAN + The lossless resistor model (IV) Vi ILd LF VHIAN - + Ld VD Vi Vi1 d·TS Vp VD - 1 If LF>>Ld: + IHIAN VHIAN = 2·Vi1·d - 4·Ld·fS ·iHIAN VHIAN = VS - - IHIAN td RLF · iHIAN iLd TS The same model is valid for the rest of the HIAN based on two inductors if LF>>Ld 11/11/2003 Advanced Techniques in Power Factor Correction 201 Single–Stage PFCs (XL) Comparing different HIAN based on the lossless resistor model Ld case d LF + LF + Ld Case (d) - - 0.5·Ld case d· iHIAN2 WLd case d = (Energy, size) Case (e) Ld = 0.25·Ld case d WLd = 0.25·WLd case d Used as reference + L F Ld = 0.5·Ld case d Ld + LF - Ld Ld = Ld case d WLd = 0.25·WLd case d WLd = 0.5·WLd case d Case (f) 11/11/2003 Ld Advanced Techniques in Power Factor Correction Case (e’) 202 Single–Stage PFCs (XLI) Set of equations to design with the lossless resistor model VS RLF • Current waveforms: DC/DC · If vg< (VC-VS) ig= 0 · If vg> (VC-VS) Vgsinwt VC VDC converter ig= (vg+VS-VC)/RLF • Conduction angle: c = 2·cos-1((VC-VS)/Vg) • Power balance: Pg = (C-sinC)·Vg2/(2·RLF) •Output voltage VDC : VDC = f1(VC, d) •Voltage VS : VS = f2(VC, d) From this set of equations, we obtain: Voltage across bulk capacitor, VC Voltage across semiconductors (from VC) 11/11/2003 Advanced Techniques in Power Factor Correction 203 Single–Stage PFCs (XLII) Integrating delaying and filter inductor into one magnetic core (I) LF Ld + Vi VHIAN Vi Ld Only one mag. core Can we integrate filter and delaying inductors into only one magnetic core? 11/11/2003 Advanced Techniques in Power Factor Correction 204 Single–Stage PFCs (XLIII) Integrating delaying and filter inductor into one magnetic core (II) Process of integration Llk1 Llk2 1:n Lm Llk2= Llk1 Llk1 a 1:1 c Lm Two-winding inductor b Two-winding inductor with r/t 1:1 Llk1 a Equivalent circuit 11/11/2003 Llk1 Advanced Techniques in Power Factor Correction b Lm c 205 Single–Stage PFCs (XLIV) Integrating delaying and filter inductor into one magnetic core (III) Example: Two-winding, top-bottom arrangement (coupling not very tight) Winding #1 c Lm=LF Llk1=Ld a E Core a c Llk1=Ld One mag. core b b E Core Winding #2 11/11/2003 Advanced Techniques in Power Factor Correction 206 Single–Stage PFCs (XLV) HIAN “case d” Examples of a converter with HIAN (I) Ld Load Line 11/11/2003 Bulk capacitor Advanced Techniques in Power Factor Correction Flyback 207 Single–Stage PFCs (XLVI) HIAN “case e” Examples of a converter with HIAN (II) LF Ld Load Line Half-Bridge Bulk capacitor 11/11/2003 Advanced Techniques in Power Factor Correction 208 Single–Stage PFCs (XLVII) HIAN “case e’ ” Examples of a converter with HIAN (III) L LD Load Line Half-Bridge Bulk capacitor 11/11/2003 Advanced Techniques in Power Factor Correction 209 Single–Stage PFCs (XLVIII) HIAN “case e” Examples of a converter with HIAN (IV) LF Ld Load Line Bulk capacitor 11/11/2003 Advanced Techniques in Power Factor Correction Flyback 210 Single–Stage PFCs (XLIX) Examples of a converter with HIAN (V) HIAN with magnetic integration Load Line Bulk capacitor 11/11/2003 Advanced Techniques in Power Factor Correction Flyback 211 Single–Stage PFCs (L) Experimental results with K=LF/Ld=0.5 (I) Flyback, 100 W, HIAN “case e” (4 diodes) Ld=76.5 mH (E16) LF=38 mH (E12) Efficiency 87% Class D 11/11/2003 Advanced Techniques in Power Factor Correction 212 Single–Stage PFCs (LI) Experimental results with K=LF/Ld=0.5 (II) Flyback, 100 W, HIAN “case e” (4 diodes) Ld=76.5 mH (E16) LF=38 mH (E12) Efficiency 87% Class D 11/11/2003 Advanced Techniques in Power Factor Correction 213 Single–Stage PFCs (LII) Experimental results with K=LF/Ld=1 (I) Flyback, 100 W, HIAN “case e” (4 diodes) Ld=105 mH (E16) LF=105 mH (E16) Efficiency 87% Class D 11/11/2003 Advanced Techniques in Power Factor Correction 214 Single–Stage PFCs (LIII) Experimental results with K=LF/Ld=1 (II) Flyback, 100 W, HIAN “case e” (4 diodes) Ld=105 mH (E16) LF=105 mH (E16) Efficiency 87% Class D 11/11/2003 Advanced Techniques in Power Factor Correction 215 Single–Stage PFCs (LIV) Experimental results with K=LF/Ld>1 (I) Half-bridge prototype + - Different HIANs 20t BYW51 200mH 0.47mF 190-265V rms 15t 20mF 47mF 32t 50V dc 15t 25-100W 0.47mF fS = 100kHz 11/11/2003 SPP11N60S5 (Cool MOS) BYW51 Advanced Techniques in Power Factor Correction 216 Single–Stage PFCs (LV) Experimental results with K=LF/Ld>1 (II) + Different HIANs - Flyback prototype 14t 25CPF40 28t 33mF 190-265V 47mF fS = 100kHz 11/11/2003 12t 50V dc 25-100W IRFPC50 Advanced Techniques in Power Factor Correction 217 Single–Stage PFCs (LVI) Experimental results with K=LF/Ld>1 (III) Implementations of the HIAN IEC 61000-3-2 Class D, 100W, 190-265V 700mH (E20) 700mH (E20) 125mH (E16) + - #2 + - 250mH (E16) #1 250mH (E16) MUR160 MUR140 1.3mH (E30) 700mH (E20) + + - 500mH (E16) #3 MUR160 MUR160 108 turns, #4 top-bottom Llk= 250mH 11/11/2003 Advanced Techniques in Power Factor Correction 218 Single–Stage PFCs (LVII) Experimental results with K=LF/Ld>1 (IV) Half-bridge prototype: Inputcurrent waveforms & harmonics Vg= 190V rms Input current [A] 0.5A/div 0.4 Pg=112W PF= 0.795 THD= 60.4% 0.2 IEC 61000-3-2 Class D measured Vg= 230V rms 0 5 10 15 20 25 30 35 1A/div 11/11/2003 Advanced Techniques in Power Factor Correction nth harmonic 219 Single–Stage PFCs (LVIII) Experimental results with K=LF/Ld>1 (V) Flyback prototype: Inputcurrent waveform & harmonics Vg= 230V rms 0.5A/div Input current [A] 0.4 Pg=107.5W IEC 61000-3-2 Class D measured 0.2 0 5 11/11/2003 10 15 20 25 30 35 nth harmonic Advanced Techniques in Power Factor Correction 220 Single–Stage PFCs (LIX) Experimental results with K=LF/Ld>1 (VI) Half-bridge with HIAN (only power stage) Flyback with HIAN (complete converter) Efficiency [%] Efficiency [%] 100 95 90 90 190V rms 190V rms 230V 80 With HIAN types #1, #2 & #3 80 40 60 80 100 Input power [W] 11/11/2003 230V 265V rms 265V rms 85 85 75 70 With HIAN type #1 40 60 80 100 Input power [W] Advanced Techniques in Power Factor Correction 221 Single–Stage PFCs (LX) Experimental results with K=LF/Ld>1 (VII) Half-bridge with HIAN Flyback with HIAN Bulk cap. voltage [V] 500 500 Bulk cap. voltage [V] Theoretical 450 265V rms 400 265V rms 400 230V rms 350 190V rms 300 + + X X X Flyback transformer in DCM 200 100 Experimental results 250 300 + + X 230V rms + X 190V rms } Experimental results Theoretical 200 0 20 40 60 80 100 0 0 20 Input power [W] 40 60 80 100 Input power [W] The maximum voltage across the bulk capacitor is lower than 450V 11/11/2003 Advanced Techniques in Power Factor Correction 222 Conclusions of the use of Single-Stage PFC (I) Single–Stage PFCs (LXI) Many Single-Stage PFCs can be described as an arrangement made up of a line rectifier, a conventional DC/DC converter and a High Impedance Active Network (HIAN) This HIAN is an additional output of the DC/DC converter that re-cycles a part of energy Using Single-Stage PFC based on the use of HIANs we achieve: Low cost and size (no second stage) The energy is stored at high voltage moderate bulk capacitor size A harmonic content low enough to comply with the IEC 610003-2 in Class A and Class D 11/11/2003 Advanced Techniques in Power Factor Correction 223 Single–Stage PFCs (LXII) Conclusions of the use of Single-Stage PFC (II) Only a few of energy is re-cycled to get compliance with the regulations High efficiency is achieved Many different HIAN implementations are possible. To comply with the regulations in Class D, those based on two inductors are the most attractive. The size of the additional inductors are very small (e.g. two E16 cores for a 100 W converter). Moreover, both inductors can be integrated into only one magnetic core The variation of the voltage across the bulk capacitor when the line voltage and the load change is reasonable (maximum voltage below 450 V DC when the line is 265 V AC) 11/11/2003 Advanced Techniques in Power Factor Correction 224 Single–Stage PFCs (LXIII) Conclusions of the use of Single-Stage PFC (III) Fast output response due to the location where the DC/DC converter is placed The main limitations are: The voltage across the bulk capacitor is not regulated. This facts deteriorates the DC/DC converter efficiency. Due to the same fact, the operation with universal line is not adequate However, for the universal line voltage range, a voltage doubler with a mechanical switch can be implemented to allow operation in this condition (this has not been explained here) 11/11/2003 Advanced Techniques in Power Factor Correction 225 Outline • Introduction • Using a simple resistor to comply with the IEC 61000-3-2 in Class A • Using an inductor to comply with the IEC 61000-3-2 in Class A and in Class D • Exploring the use of isolated Resistor Emulators as the only conversion stage for medium-speed response applications • High-efficiency post regulators used to improve the transient response of Resistors Emulators • Very simple single-stage PFCs • Very simple current shaping techniques for very low-cost applications 11/11/2003 Advanced Techniques in Power Factor Correction 226 Objective: A new low-cost method to control PFC in CCM Very simple shaping (I) Power Output Factor Line Corrector Current Feedback-Loop - Voltage Feedback-Loop Control circuitry Previous methods: Control based on an analog multiplier Voltage-Follower Control 11/11/2003 Advanced Techniques in Power Factor Correction 227 Very simple shaping (II) Types of control: control based on an analog multiplier DC/DC converter Low-Pass filter 11/11/2003 Advanced Techniques in Power Factor Correction In CCM Perfect PF & THD Low losses in the transistor Current sensor Multiplier More expensive 228 Very simple shaping (III) Types of control: VoltageFollower Control “High ZO” dc-to-dc converter Low-Pass filter 11/11/2003 Advanced Techniques in Power Factor Correction No current sensor No multiplier Cheaper Lower losses in the diode Only high-outputimpedance topologies (converters in DCM) Sometimes THD Higher total losses 229 Very simple shaping (IV) Comparing semiconductor currents for both control methods (I) Example: battery charger based on a Flyback Vinput: 85-265 Vac VOutput: 10-14 V IOutput: 3-10 A CCM Lm= 760 mH 4 itransistor 4.36 A idiode 66.27 A 50 2 0 time DCM Lm= 28 mH 20 11/11/2003 time itransistor 14.66 A 100 10 0 0 idiode 109.98 A 50 time 0 Advanced Techniques in Power Factor Correction time 230 Very simple shaping (V) CCM 4 Comparing semiconductor currents for both control methods (II) (Lm= 760 mH, E42/17/12) itransistor DCM 20 (Lm= 28 mH, E30/15/13) ) itransistor 10 2 0 time itransistor RMS = 2.16 A 0 time itransistor RMS = 3.55 A Losses in the transistor operating in DCM are 3.552 / 2.162 = 2.7 times as high as in CCM Operation in CCM is desirable from the point of view of efficiency 11/11/2003 Advanced Techniques in Power Factor Correction 231 Very simple shaping (VI) Multiplier control (MC) Comparing controllers for both control methods Voltage-Follower Control (VFC) DC/DC converter DC/DC converter in DCM Low-Pass filter Low-Pass filter Controller cost: UC3843 0.5 € UC3525 1.1 € Controller cost: UC3854A 5.3 € UC3854B 8.2 € Operation in DCM is desirable from the point of view of the controller cost 11/11/2003 Advanced Techniques in Power Factor Correction 232 Very simple shaping (VII) Can we have some of advantages of both methods together? ConductionAngle Control DC/DC converter Very cheap circuit 11/11/2003 Low-Pass filter Advanced Techniques in Power Factor Correction In CCM (as MC) Low losses (as MC) Low cost (as VFC) Compliance with regulations Current sensor No perfect sinusoidal 233 Very simple shaping (VIII) Principle of operation of Conduction Angle Control (I) iB·b·R1 + - + + R1 ve - iB·b·R1 + iB vs + b - ve vs Active mode t Saturation Transistor in active mode: Transistor in saturation: 11/11/2003 vs = ve - iB·b·R1 vs = 0 Advanced Techniques in Power Factor Correction 234 Very simple shaping (IX) Principle of operation of Conduction Angle Control (II) This signal can be used as reference for the current feedback loop iB·b·R1 + - + + R1 ve - ve + iB3·b·R1 vs1 iB vs - iB1·b·R1 iB2·b·R1 b + vs2 vs3 t iB1 < iB2 < iB3 (The same if it is controlled by light) 11/11/2003 Advanced Techniques in Power Factor Correction 235 Very simple shaping (X) Line Implementation without galvanic isolation DC/DC converter in CCM or DCM Standard controller Output Current feedback loop Shaper Low-pass Filter Voltage feedback loop 11/11/2003 Advanced Techniques in Power Factor Correction 236 Example: Implementation based on a boost converter Very simple shaping (XI) Output R1 Line R2 Standard controller Current feedback-loop Low-pass filter Q1 TL431 To perform the current reference 11/11/2003 Voltage feedback-loop Advanced Techniques in Power Factor Correction 237 Very simple shaping (XII) Line Implementation without galvanic isolation DC/DC converter in CCM or DCM Output Current feedback loop Standard controller Voltage feedback loop Low-pass Filter Optocoupler 11/11/2003 TL431 Advanced Techniques in Power Factor Correction 238 Example: Implementation based on a flyback converter Very simple shaping (XIII) Output R1 Line R2 Standard controller Current feedback-loop Low-pass filter Q1 To perform the current reference 11/11/2003 TL431 Voltage feedback-loop Advanced Techniques in Power Factor Correction 239 Very simple shaping (XIV) Design procedure Output ig R1 Power stage R2 Current feedback loop Q1 Filter Voltage feedback loop @ Minimum line voltage and maximum output power: R1, R2 and the input-current feedback loop must be designed to supply the total power to the load. Q1 will be held in cut-off by the output-voltage feedback loop. ig @ 190V AC, PO max ig @ Nominal line voltage and maximum output power: 11/11/2003 @ 230V AC, PO max D=22.5º Advanced Techniques in Power Factor Correction D 240 Very simple shaping (XV) ig Line waveforms at full load D Design for the American range Design for the Universal range Voltage Dead angle Voltage Dead angle Voltage Design for the European range* Dead angle 85 V AC 110 V AC 130 V AC 0º 37.5º 55.7º 85 V AC 0º 110 V AC 230 V AC 37.5º 98.8º 190 V AC 230 V AC 265 V AC 0º 29.2º 46.2º * Also valid for Universal range if R2 is properly changed 11/11/2003 Advanced Techniques in Power Factor Correction 241 Very simple shaping (XVI) Line waveforms for different loads Decreasing loads Classical control method ig (at full load) ig Conduction Angle Control ig ig (at full load) ig ig Remember: IEC 61000-3-2 should be complied only at full load! 11/11/2003 Advanced Techniques in Power Factor Correction 242 Very simple shaping (XVII) Small-signal model of the Power Stage (including the input-current feedback loop) DC/DC converter Power stage + current loop Low-Pass filter Output-voltage feedback loop Objective: to have a model of the power stage (+ current loop) to properly calculate the output-voltage feedback loop 11/11/2003 Advanced Techniques in Power Factor Correction 243 Very simple shaping (XVIII) Averaging process Power stage + current loop Input iO DC/DC converter Output vO VgP·sinwt VgP·2/ vOav Control VgP·2/ igav iOav CB vOav iO iOav Power Power stage + current loop 11/11/2003 Advanced Techniques in Power Factor Correction 244 Very simple shaping (XIX) Choosing the control variable Power Power stage + current loop igav iOav CB VgP·2/ vOav Control i Cact iC iCact = b·ib ib b we choose iled iC iCact CTR 11/11/2003 Advanced Techniques in Power Factor Correction iCact = CTR·iled 245 Very simple shaping (XX) Steady-state and perturbed variables Power Power stage + current loop igav iOav vOav CB VgP·2/ iCact Steady-state Perturbation iO îOav iOav IOav iOav t 11/11/2003 Advanced Techniques in Power Factor Correction 246 Very simple shaping (XXI) Value of igav Power Power stage + current loop igav iOav CB VgP·2/ Input port vOav Output port iCact From the theoretical study: igav 2 v gP R eq π R S R1 where: (sin R eq C 2 - C 2 cos C R1 R 2 R1 R 2 R i C - D 2 a cos( 1 Cact ) v gP 11/11/2003 2 ) RS = current sensor gain vgP = line voltage (peak value) Advanced Techniques in Power Factor Correction 247 Very simple shaping (XXII) Small-signal circuit for the input port Power Power stage + current loop igav VgP·2/ Input port îgav igav iCact Power Power stage + current loop 2 v gP R eq π R S R1 (sin - 2 cos C 2 îgav GgC îCact Ggv v̂ gP GgC·îCact GgC Ggv Input port 11/11/2003 2 C After perturbing igav where: (Ggv)-1 C Advanced Techniques in Power Factor Correction R eq F C RS 2 R eq R1 R S sin FC 2 248 ) Very simple shaping (XXIII) Value of iOav Power Power stage + current loop igav iOav CB VgP·2/ Input port iCact vOav Output port From the theoretical study: iOav v2 gP R eq 2π v Oav R S R 1 ( C - sin C ) where: vOav = output voltage 11/11/2003 Advanced Techniques in Power Factor Correction 249 Very simple shaping (XXIV) Small-signal circuit for the output port (I) Power Power stage + current loop iOav iOav CB vOav v2 gP R eq 2π v Oav R S R 1 ( C - sin C ) After perturbing iOav Output port iCact îOav GOC îCact GOg v̂ gP GOV v̂ Oav where: GOC - GOg 11/11/2003 VgP R eq VOav R S 2 IOav VgP 1 - cos F C 1 - cos 2 VgP R eq VOav R S R 1 FC GOV - IOav VOav - 2 sin F C Advanced Techniques in Power Factor Correction 250 1 RO Very simple shaping (XXV) Small-signal circuit for the output port (II) Power Power stage + current loop iOav CB iCact vOav After perturbing iOav Output port Power Power stage + current loop GOC· îCact 11/11/2003 -(GOv)-1 Advanced Techniques in Power Factor Correction îOav GOg· ^ vgP CB + ^ v Oav 251 Very simple shaping (XXVI) îgav Small-signal circuit for both input and output ports Power Power stage + current loop (Ggv)-1 GgC·îCact -(GOv)-1 GOC· îCact Input port îCact îOav GOg· ^ vgP + ^ v Oav CB - Output port • The same structure as in the case of the previous control methods • First-order transfer functions • Different value for the parameters 11/11/2003 Advanced Techniques in Power Factor Correction 252 Very simple shaping (XXVII) Transfer function between line voltage and output voltage RO G vOvg (s) v̂ Oav v̂ gP + ^iOav GOC·îCact GOg ^ GOg·v gP CB ^ vOav - R O rload R O rload R O rload 1 s CB R O rload where: RO=VO/IO rload= dynamic load First-order transfer function 11/11/2003 Advanced Techniques in Power Factor Correction 253 Very simple shaping (XXVIII) Transfer function between control and output voltage ^iOav GOC·îCact RO G vOiC (s) v̂ Oav îCact CB ^ GOg·v gP GOC + ^ vOav - R O rload R O rload R O rload 1 s CB R O rload Also, first-order transfer function 11/11/2003 Advanced Techniques in Power Factor Correction 254 Very simple shaping (XXIX) G vOiC (s) v̂ Oav îCact GOC Variation of transfer function between control and output voltage with the line voltage (I) R O rload R O rload R O rload 1 s CB R O rload being: GOC - VgP R eq VOav R S 1 - cos F C 1 - cos2 GOC 10 FC 2 5 where: F C 2 a cos( R 1 ICact ) VgP 0 1 1.5 2 2.5 VgP/VgPmin 3 Slight variation of GOC when VgP changes 11/11/2003 Advanced Techniques in Power Factor Correction 255 Very simple shaping (XXX) Variation of transfer function between control and output voltage with the line voltage (II) Comparing these results with the ones obtained using control based on a multiplier GOC 10 Control based on a multiplier 5 0 Conduction Angle Control 1 11/11/2003 1.5 2 VgP/VgPmin 2.5 3 GOC undergoes a lower variation in the case of the Conduction Angle Control. This fact simplifies the design of the output-voltage feedback loop. Advanced Techniques in Power Factor Correction 256 Prototype for experimental results (based on a Flyback converter) Very simple shaping (XXXI) Output Line Vg: 190265 V AC R1 PO: 80 W VO: 12 V R2 Standard controller UC 3825 Low-pass filter MCT2 TL431 11/11/2003 Advanced Techniques in Power Factor Correction 257 Very simple shaping (XXXII) Implementation of the input-current feedback loop based on a standard controller for Switching Mode Power Supplies 10 K 1 : 50 12 nF 820 pF 220 3.7 M Current sensor From the line-rectifier output R1 R2 MCT2 11/11/2003 1K To the UC 3825’s comparator 47 K UC 3825’s error amplifier 33 nF 820 pF Bias + 5.1 V + 5.1 V 47 K R1 = 1M R2 = 10 K Advanced Techniques in Power Factor Correction 258 Very simple shaping (XXXIII) Experimental results (I) + - vsensor R1 vR2 + R2 1 V/div D vR2 - @ 190 V AC, full load vsensor vsensor vsensor vR2 D vR2 1 V/div @ 230 V AC, full load 11/11/2003 D increases when VgP increases 1 V/div @ 265 V AC, full load Advanced Techniques in Power Factor Correction 259 Very simple shaping (XXXIV) Experimental results (II) + vsensor D vR2 R1 vsensor vsensor D D 0.5 V/div vR2 - @ 230 V AC, full load vR2 @ 230 V AC, 12 V, 2 A 11/11/2003 + R2 1 V/div vsensor 0.2 V/div vR2 D increases when IO decreases @ 230 V AC, 12 V, 0.85 A Advanced Techniques in Power Factor Correction 260 Very simple shaping (XXXV) Experimental results (III) Line current @ 190 V AC, full load 0.33 A/div @ 265 VAC, full load @ 230 V AC, full load 0.33 A/div 0.33 A/div @ 190 V AC, 12 V, 2 A @ 230 V AC, 12 V, 2 A @ 265 V AC, 12 V, 2 A 0.167 A/div 0.167 A/div 0.167 A/div 11/11/2003 Advanced Techniques in Power Factor Correction 261 Very simple shaping (XXXVI) Experimental results (IV) Line current (A) Harmonic content 0.4 @ 230 V AC, full load Class D limits 0.2 Measured 0 5 10 15 20 25 30 35 nth harmonics 0.33 A/div Line current (A) 2 @ 230 V AC, 102.8 W THD = 24.5% PF = 0.968 Class A limits 1 Measured 0 5 10 15 20 25 30 35 nth harmonics 11/11/2003 Advanced Techniques in Power Factor Correction 262 Very simple shaping (XXXVII) Experimental results (V) Verifying the small-signal model (I) îCact Simulated iled iCact [Volts] 1.5 vO(t)-VOav 1 (Pspice simulation) CTR iCact = CTR·iled 0.5 ^ v Oav(t) 0 (small-signal model) -0.5 0.6 11/11/2003 0.7 Advanced Techniques in Power Factor Correction 0.8 0.9 1 t [s] 263 Very simple shaping (XXXVIII) Experimental results (VI) Verifying the small-signal model (II) ^ vgP Simulated ^ vgP [Volts] 0.5 ^ v Oav(t) (small-signal model) 0 -0.5 vO(t)-VOav (Pspice simulation) -1 11/11/2003 0.6 0.7 Advanced Techniques in Power Factor Correction 0.8 0.9 1 t [s] 264 Very simple shaping (XXXIX) Verifying the small-signal model (III) Experimental results (VII) îCact Experimental Measured Output voltage iled Average smallsignal model iC CTR iCact = CTR·iled 11/11/2003 Advanced Techniques in Power Factor Correction 265 Very simple shaping (XL) Verifying the small-signal model (IV) Experimental results (VIII) ^ vgP Experimental ^ vgP Measured Output voltage 11/11/2003 Advanced Techniques in Power Factor Correction Average smallsignal model 266 Very simple shaping (XLI) Conclusions of the use of very simple current shaping techniques for very low-cost applications (I) The Conduction Angle Control method can be used in CCM (as the control based on a multiplier) Low losses (as the control based on a multiplier) Low cost controller (as Voltage Follower Control) Current sensor and current feedback loop No perfect sinusoidal, but compliance with IEC 61000-3-2 is achieved 11/11/2003 Advanced Techniques in Power Factor Correction 267 Very simple shaping (XLII) Conclusions of the use of very simple current shaping techniques for very low-cost applications (II) An average small-signal model of the PFC controlled by Conduction Angle has been obtained The transfer functions between control and output voltage and between input voltage and output voltage have also been obtained. As in the case of other control methods, they are first- order transfer functions However, the transfer function between control and output voltage is almost constant when the value of the AC input voltage varies. This fact simplifies the output-voltage feedback loop 11/11/2003 Advanced Techniques in Power Factor Correction 268
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