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EET 423 POWER ELECTRONICS -2 POWER ELECTRONICS 2 Prof R T Kennedy 1 SMPS OPERATION QUANTIZED POWER/ENERGY TRANSFER VOLTAGE REGULATION POWER ELECTRONICS 2 Prof R T Kennedy 2 BASIC COMPONENTS sw1 Ein NON-ISOLATED C sw2 L R sw1 sw2 ISOLATED SW1 controllable Ein T C L R BJT MOSFET IGBT SW2 non-controllable (RECTIFIER pn or Schottky) controllable (MOSFET) POWER ELECTRONICS 2 Prof R T Kennedy 3 COMPONENT INTERCONNECTIONS 1 2 sw1 C sw2 Ein R L 3 3 POWER ELECTRONICS 2 Prof R T Kennedy 4 SWITCHING CYCLE SUB INTERVALS L E in C R a E in C L R b E in L C R c POWER ELECTRONICS 2 Prof R T Kennedy 5 BASIC TOPOLOGIES & CONSTRAINTS SWITCH sw1 12 L Ein 13 C R sw2 sw2 L E in sw1 C R 23 PROBLEM L L L inrush current short circuit source output capacitor voltage discharge Sw1 Sw2 ON OFF J OFF ON J OFF ON OFF ON J L YES YES YES NO N POWER ELECTRONICS 2 Prof R T Kennedy 6 BASIC-1 BUCK CONVERTER Ei n L sw1 C sw2 R Ei n sw1 on L C R a L Ei n c L C R Ei n sw2 on C R Vout POWER ELECTRONICS 2 Prof R T Kennedy 7 BASIC-2 BOOST CONVERTER sw2 L L C E in E in sw1 sw1 on R sw2 on R b L L E in E in C C R C R a POWER ELECTRONICS 2 Prof R T Kennedy 8 BUCK TOPOLOGY TERMINOLOGY • Step Down Converter output voltage input voltage • Direct Converter direct energy transfer from input to output (sw1 on) • Forward Converter energy transferred forward supply load (sw1 on) • Single Ended Converter common input-output rail • Non-Isolated Converter no transformer input – output isolation POWER ELECTRONICS 2 Prof R T Kennedy 9 BUCK TOPOLOGY TERMINOLOGY • Step Down Converter output voltage input voltage • Direct Converter direct energy transfer from input to output (sw1 on) • Forward Converter energy transferred forward supply load (sw1 on) • Single Ended Converter common input-output rail • Non-Isolated Converter no transformer input – output isolation POWER ELECTRONICS 2 Prof R T Kennedy 10 BOOST TOPOLOGY TERMINOLOGY • Step Up Converter output voltage input voltage • Indirect Converter no direct energy transfer from input to output • Single Ended Converter common input-output rail • Non-Isolated Converter no transformer input – output isolation POWER ELECTRONICS 2 Prof R T Kennedy 11 BOOST TOPOLOGY TERMINOLOGY • Step Up Converter output voltage input voltage • Indirect Converter no direct energy transfer from input to output • Single Ended Converter common input-output rail • Non-Isolated Converter no transformer input – output isolation POWER ELECTRONICS 2 Prof R T Kennedy 12 BUCK-BOOST COMBINED CONVERTER L E in L E in C R C R POWER ELECTRONICS 2 Prof R T Kennedy 13 BUCK-BOOST COMBINED CONVERTER L E in L E in C R C R POWER ELECTRONICS 2 Prof R T Kennedy 14 BUCK-BOOST COMBINED CONVERTER L L E in C R SWITCH SYNCHRONISATION POWER ELECTRONICS 2 Prof R T Kennedy 15 BUCK-BOOST COMBINED CONVERTER L Ein sw1 on C R b L Ein C sw2 on R c POWER ELECTRONICS 2 Prof R T Kennedy 16 BUCK-BOOST COMBINED CONVERTER Ein C L R Vout NOTE VOLTAGE INVERSION POWER ELECTRONICS 2 Prof R T Kennedy 17 BOOST-BUCK COMBINED CONVERTER L2 L1 E in E in C1 R C2 R POWER ELECTRONICS 2 Prof R T Kennedy 18 BOOST-BUCK COMBINED CONVERTER L2 L1 E in E in C1 R C2 R POWER ELECTRONICS 2 Prof R T Kennedy 19 BOOST-BUCK COMBINED CONVERTER L2 L1 E in C2 C1 SWITCH R SYNCHRONISATION POWER ELECTRONICS 2 Prof R T Kennedy 20 BOOST-BUCK COMBINED CONVERTER L1 Ein L2 C1 C2 R Vout NOTE VOLTAGE INVERSION POWER ELECTRONICS 2 Prof R T Kennedy 21 SMPS TOPOLOGIES POWER SUPPLIES SWITCHING LINEAR HARD SERIES SHUNT SWITCHED MODE SMPS SOFT RESONANT RPS HYBRID QRPS 2 BASIC TOPOLOGIES BOOST BUCK BUCK DERIVED BOOST DERIVED COMBINED SEPIC FORWARD PUSH PULL 1 or 2 Transistor BUCK-BOOST BUCK-BOOST DERIVED BOOST –BUCK DERIVED BRIDGE FLYBACK HALF BOOST -BUCK FULL CUK 1 or 2 Transistor POWER ELECTRONICS 2 Prof R T Kennedy 22 SMPS TOPOLOGIES POWER ELECTRONICS 2 Prof R T Kennedy 23 RECAP SMPS APPLICATIONS POWER ELECTRONICS 2 Prof R T Kennedy 24 INDUCTOR CURRENT MODES Imax Iind 1 2 o Imin 2 1 CCM t Imax Iind I I av max 2 0 t BOUNDARY Imax Iind DCM o 1 2 1 3 t Prof R T Kennedy 2 3 Imi n POWER ELECTRONICS 2 25 BUCK CONVERTER CIRCUIT CURRENTS Ii n Ids a IL Ifwd IL b Iout L IC Ids Ei n Ifwd C R Vout POWER ELECTRONICS 2 Prof R T Kennedy 26 Vgs BUCK CONVERTER CIRCUIT CURRENTS CCM 0 Iout 0 IC 0 IC,av= 0 0 IL 0 IL,av=Iout 0 Ids,av 0 Ids Iin,av Iout IL=Ids+Ifwd 0 0 Ifwd 0 IL=Iout+IC 0 Iout Ifwd,av POWER ELECTRONICS 2 Prof R T Kennedy 27 Vgs BUCK CONVERTER CIRCUIT CURRENTS CCM 0 Iout 0 IC 0 IC,av= 0 0 IL 0 IL,av=Iout 0 Ids,av 0 Ids Iin,av Iout IL=Ids+Ifwd 0 0 Ifwd 0 IL=Iout+IC 0 Iout Ifwd,av POWER ELECTRONICS 2 Prof R T Kennedy 28 Vgs Iout IC BUCK CONVERTER CIRCUIT CURRENTS DCM 0 0 IC,av= 0 0 IL=Iout+IC IL,av=Iout IL 0 Ids Ids,av Iin,av 0 IL=Ids+Ifwd Ifwd Ifwd,av 0 POWER ELECTRONICS 2 Prof R T Kennedy 29 BOOST CONVERTER CIRCUIT CURRENTS Iin IL L b Iout IC Ids Ei n Ifwd a Ifwd Ids Ifwd C R Vout POWER ELECTRONICS 2 Prof R T Kennedy 30 Vg 0 Isout 0 IC BOOST CONVERTER CIRCUIT CURRENTS CCM IC,av= 0 0 Ifwd=Iout+ IC IL,av=Iin,av Ifwd 0 Ifwd,av Ids,av Id s Iout IL,av IL=Ids+ Ifwd 0 IL,av IL 0 POWER ELECTRONICS 2 Prof R T Kennedy 31 Vg 0 Isout 0 IC 0 Ifwd BOOST CONVERTER CIRCUIT CURRENTS DCM IC,av= 0 Ifwd=Iout+ IC Ifwd,av = Iout 0 Id s Ids,av IL=Ids+ Ifwd 0 IL,av = Iin,av IL 0 Prof R T Kennedy POWER ELECTRONICS 2 32 WAVEFORM FORMULAE C DC- average 0 DC ( 1 - D) T DT AC- rms total- rms D(1 D) C D C B C kC A B D 2 A DC 0 DT k 2( B A) B A D 2 D( A B) ( A AB B 2 ) 3 2 k2 D(1 ) D2 C 12 2 D 2 ( A AB B 2 ) 3 k2 D(1 ) C 12 (1 - D) T C A B 2 y 0 0 y Y 3 Y y 12 3 Y 12 POWER ELECTRONICS 2 Prof R T Kennedy 33 WAVEFORM FORMULAE DC- average C D C 2 AC- rms D D2 C 3 4 total- rms D D2 C 3 4 0 D T (1-D) T POWER ELECTRONICS 2 Prof R T Kennedy 34 TRAPEZOIDAL-SQUAREWAVE RMS COMPARISON B kC 4 1.155 3 C A 0 D T (1 - D) T rms, trap rms, sq rms, trap k2 1 rms, sq 12 1 2( B A) k B A C A B 2 0 2 k square wave POWER ELECTRONICS 2 Prof R T Kennedy 1 CCM-DCM boundary peak peak ripple k 2 pulse average 35 PARASITICS PARASITIC EFFECTS LOSSY RESISTIVE SOURCE RS INDUCTOR rL MAGNETICS core loss winding loss CAPACITOR esr LOSSLESS CAPACITOR esl SEMICONDUCTORS RECTIFIER VF I rev rec INDUCTOR TRANSFORMER leakage L stray capacitance TRANSISTOR ON Loss SWITCHING loss BJT /IGBT ce BJTV/IGBT MOSFET rds,on MOSFET Vce rds,on turn on turn on turn off turn off POWER ELECTRONICS 2 Prof R T Kennedy 36 POWER and POWER LOSSES MOSFET IM 0 Pmos ,loss I M 2 Dmos rds,on DmosT T IGBT IM 0 DigbtT T BJT IM 0 I rms 2 rds,on Pmos ,loss Pigbt,loss I av Vce,on Pigbt,loss I M Digbt Vce,on PBJT ,loss I av Vce( sat ) PBJT ,loss I M Dbjt Vce( sat ) DbjtT T POWER ELECTRONICS 2 Prof R T Kennedy 37 POWER and POWER LOSSES RECTIFIER IM 0 Prect , loss Prect , loss I M Drect V F DrectT T RESISTOR IM I av V F I rms 2 R PR, loss PR, loss IM 2 D R 0 R DT T POWER ELECTRONICS 2 Prof R T Kennedy 38 SYSTEM POWERS and EFFICIENCY v(t ) i (t ) p (t ) Pav 1 T v(t ) i (t ) dt T 0 T T Pav 0 v(t ) dt 0 i(t ) dt T T Pav voltage area current area period period Pav Vav I av POWER ELECTRONICS 2 Prof R T Kennedy 39 SYSTEM POWERS and EFFICIENCY efficiency Pout, av Pin, av efficiency Pin, av Ploss Pin, av Pout, av Pout, av Ploss Vout I out Ein I in, av POWER ELECTRONICS 2 Prof R T Kennedy 40 VOLTAGE TRANSFER FUNCTION ANALYSIS • ENERGY BALANCE • POWER BALANCE • VOLT-TIME INTEGRAL POWER ELECTRONICS 2 Prof R T Kennedy 41 FARADAY’S VOLT-TIME INTEGRAL IM INDUCTOR CURRENT Im current start and finish at same value 0 t V1 INDUCTOR VOLTAGE 0 t1 t V2 t2 VL, av 1 T di L dt T 0 dt VL, av 1 T L di T 0 VL, av L T I T 0 VL, av L I 0 IT 0 T T EQUAL AREAS T 0 v(t ) dt V1 t1 0 V2 t2 POWER ELECTRONICS 2 Prof R T Kennedy 42 BUCK and BOOST CONVERTERS VOLTAGE TRANSFER FUNCTIONS 5 BOOST 4.5 Vout 1 1 Ein 1 Dsw1 4 3.5 Vout Ein 3 2.5 2 1.5 BUCK 1 Vout Dsw1 1 Ein 0.5 0 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 Dsw1 Prof R T Kennedy 1 POWER ELECTRONICS 2 43 BUCK-BOOST BOOST- BUCK CONVERTERS VOLTAGE TRANSFER FUNCTIONS 1 INVERTED STEP DOWN (<1) 0 1 2 3 4 Vout Ein 5 INVERTED STEP UP (>1) 6 7 8 9 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1 Dsw1 POWER ELECTRONICS 2 Prof R T Kennedy 44 PRACTICAL SYSTEMS Vout Ein Vout I out Ein I in, av I in, av I Vout Vout efficiency Ein practical Ein ideal POWER ELECTRONICS 2 Prof R T Kennedy 45