* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download phase shift pwm with double two-switch bridge for high
Wireless power transfer wikipedia , lookup
Transformer wikipedia , lookup
Power factor wikipedia , lookup
Stepper motor wikipedia , lookup
Electrification wikipedia , lookup
Electric power system wikipedia , lookup
Spark-gap transmitter wikipedia , lookup
Mercury-arc valve wikipedia , lookup
Electrical ballast wikipedia , lookup
Resistive opto-isolator wikipedia , lookup
Power engineering wikipedia , lookup
Charging station wikipedia , lookup
Current source wikipedia , lookup
History of electric power transmission wikipedia , lookup
Power inverter wikipedia , lookup
Power MOSFET wikipedia , lookup
Voltage regulator wikipedia , lookup
Transformer types wikipedia , lookup
Stray voltage wikipedia , lookup
Electrical substation wikipedia , lookup
Surge protector wikipedia , lookup
Variable-frequency drive wikipedia , lookup
Capacitor discharge ignition wikipedia , lookup
Three-phase electric power wikipedia , lookup
Opto-isolator wikipedia , lookup
Voltage optimisation wikipedia , lookup
Mains electricity wikipedia , lookup
Alternating current wikipedia , lookup
Pulse-width modulation wikipedia , lookup
PHASE SHIFT PWM WITH DOUBLE TWO-SWITCH BRIDGE FOR HIGH POWER CAPACITOR CHARGING U.S.Karandikar#, Yashpal Singh, A.C. Thakurta Power Supply and Industrial Accelerator Division (PSIAD), Raja Ramanna Center for Advanced Technology (RRCAT), Indore, India 452013. Design Parameter Maximum Output Voltage Load Capacitance Pulse Repetition Rate Charging Time Average Charging Current Charging Rate Peak Charging Rate Primary DC Bus Voltage Inverter Switching Frequency Value 2500 50 25 35 3.57 4464 8928 500 33 Units Volts µF Hz ms A J/sec J/sec V kHz D 2 PROPOSED SCHEME The proposed converter has fallowing features. 1Double two-switchPower Bridge The tow-switch converters have proved their reliability for low power forward and fly-back converters. Full bridge is commonly used for high power but suffers from shoot-through problem. Driver modules are used to address shoot-through problem but they have their own limitations. In the proposed scheme a full bridge is realized using double two-switch power bridges in push pull to enhance reliability with two identical primary windingsas shown in fig-2. This configuration was used for high voltage [3]. We propose to use it for capacitor charging with LC filter at output. 2 INTRODUCTION A high voltage pulse charger is required to charge a 60 nF capacitor bank up to 60 kV at 25 Hz for pulse generation. The pulse charger is commonly used for charging h.v. capacitor bank in short duration [1-2]. It utilizes resonance for transfer of energy from a low voltage capacitor to high voltage capacitor by means of a step-up transformer. The proposed charger is designed to charge the low voltage capacitance in the given time for repeated charge transfer. [fig-1] DESIGN PARAMETERS D Abstract: Pulse power supply systems working at higher voltage and high repetition rate demands for higher power from capacitor chargers. Capacitor charging requirement become more challenging in such cases. In pulse power circuits, energy storage capacitor should be charged to its desired voltage before the next switching occurs. It is discharged within a small time, delivering large pulse power. A capacitor charger has to work with wide load variation repeatedly. Many schemes are used for this purpose. The proposed scheme aims at reducing stresses on switches by reducing peak current and their evils. A high voltage power supply is designed for capacitor charging. The proposed scheme is based on a Phase-Shifted PWM without using any extra component to achieve soft switching. Indirect constant average current capacitor charging is achieved with a simple control scheme. A double two-switch bridge is proposed to enhance reliability. Power supply has been developedto charge a capacitor of 50uF to 2.5 kV at25Hz. 2 1 2 S 1 S 1 3 T1 1 7 2 D 2 1 2 9 5 2 2 4 1 Vin D TRNSFMR CHAGING PERIOD S 1 S 1 Vi 1 Tc 1 OUTPUT VOLTAGE Vf REFRESH PERIOD 2 Q1 DISCHAGING PERIOD TIME Fig1: Charge discharge cycles of a CCPS # [email protected] Fig2: Double two-switch converter circuit LOAD 2 Phase shift PWM Phase shift PWM for power conversion is popular to provide soft switching with loss less snubber. The output inductor current and magnetizing current is utilized to achieve soft switching with capacitors across switches as loss less snubber.No extra component is required so complexity is avoided.Phase shift PWM technique has been used and reported with double two-switch power bridges for high power application with soft switching [4]. We have used a phase shift PWM IC UCC3895 to generate phase shifted drive signals for switches and have demonstrated the use of this scheme for capacitor charging applications [5]. 3ConstantCurrent Charging without current sense A simple control scheme is adopted for a constant average current capacitor charging. A reference ramp is generated by using straight line equitation: 𝑣 = 𝑉𝑖 + (𝑉𝐹 − 𝑉𝑖 ) × 𝑡 𝑇𝑐 +ADD + S/H Vi PHASE SHIFT PWM SD + SENSE + ADD _ A prototype power supply was assembled around step- up transformer with turn ratio 1:8 (Np:Ns). Ferrite cores U94 four pairs are used and litz wire was used for primary winding. The transformer was placed in oil tank for cooling and insulation. Output inductor used was a 3mH made with EE65 4 pairs also used litz wire. IXYS make diodes DS40-18A (1800V/40A/100ns) are used for high voltage rectification and DSEI2 x 31 (1000V/30A/35ns) are used for free wheeling. For initial testing an SCR HF80TB10 Hirect make (1kV/80A) was used for discharging capacitor and MOSFETs IRFP460 (500V/20A) was used in switching bridge. Power supply was tested to charge a 50 µF capacitor up to ~1kV in 35ms. Tektronics make DSO TPS 2024 was used foracquiring traces. Tektronics probe P5100 (100:1) is used for high voltage measurement. Pearson CT P6600 (10:1) used for primary current of both the windings in common and a 1Ω shunt was used for measuring secondary current. E/A . - REFERANCE +INT . - Vf EXPERIMENTAL RESULTS SWITCH DRIVE where v & t are variables. Vi is capacitor voltage present before start of charging VF is final output voltage and TCis time available for charging for each cycle. This ramp is continuously tracked and indirectly a constant average current is achieved without using current signals. reference and Vi.An error is used to modify the signal given to PSPWM controller. The synchronism is maintained by a timing circuit. TIMING CIRCUIT SCR TRIGGER O/C & O/V Fig3:Block schematic of control scheme As shown in the Fig-3above a sample and hold circuit is used to store the information (Vi). A sample and hold signal is given by timing circuit before starting of each charging cycle. A ramp is generated using Fig 4: Capacitor charging voltage: Green,Secondary current: Red, Primary current: Blue. Figure-4 shows test results. Trace-3 shows capacitor was charged to 960V in 35 ms. A linear capacitor charging shows that average charging current was constant. It can be confirmed by trace-2 for secondary current. For capacitor charging average current Iav can be given by equation: 𝐼𝑎𝑣 = 𝐶 × ∆𝑉 𝑇𝑐 For our test it is 1.4A. The average of trace-2 in figure-4 gives the same. Primary current is also seen nearly constant for the cycle. Fig 5: Primary current: Blue correspondingSwitch drives for 0.4 duty. with In figure-5&6 trace-1 shows combined primary current with drives of corresponding switches of PSPWM inverter. Switches can be seen turning ON with negative current conforming ZVS operation. Fig 6: Primary current: Blue with corresponding Switch drives for higher duty. With a double two-switchpower bridge duty factor can be extended to higher side to make use of full time. Figure-6 shows operation at higher duty factor. CONCLUSION A double two-switchpower bridgehas enhanced reliability. PSPWM has reduced switching losses. The control scheme has simplified average current control. The scheme is a good choice for capacitor charging with constant average current. ACKNOWLEDGEMENT The authors thank Shri P. Renukanath& his team for his active support for designing and providing transformers and shri Yogesh Raikwar & Shri Yunus Khan for technical assistance during assembly and testing. REFERENCES 1: Yashpal Singh et. al. “Development of Indus-2 Kicker Power Supplies” InPAC-2003” 2: U.S.Karandikar et. al. “Current Control Mode Flyback as CCPS” InPAC-2006. 3: Min Chen, et. al.“Transformer Secondary Leakage Inductance Based ZVS Dual Bridge DC/DC Converter” 0-7803-7768-0/03/$17.00© 2003 IEEE 4: Nasser H. Kutkutet. al. “A dual bridge high current DC to DC converter with soft switching capability” IEEE Industry Applications Society Annual Meeting New Orleans, Louisiana, October-5-9,1997. 5: Texas Instruments ‘SLUS157N − DECEMBER 1999 − REVISED MAY 2009.