Study Of Parallel Current Sharing For High Power Switch Supply

Nowadays the technology of switching power supply is gradually being perfect. However, there is no end to the demand for a high-power, high performance power supply. The technique of Soft-switching PWM and paralleling current-sharing is a tendency of the power electronics, and the combination of them can well satisfy the need of high-power supply on characteristic, capacity, weight, volume, efficiency and reliability. In the paper, a high power switch supply is developed using phase- shifted full-bridge ZVS PWM DC/DC converter circuit and the current-sharing circuit is designed for parallel operation of multi- module. The relative operation principle is analyzed and the circuit parameters are designed. At last, a prototype is developed to validate the result.The theory of phase-shifted full-bridge ZVS PWM DC/DC converter circuit is studied and the phase-shifted controller UC3875 is used for phase-shifted control circuit. The methods of realize ZVS for the lagging arm and the loss of duty cycle of output voltage of secondary winding are studied. The series of resonant inductance is adopted in the circuit to realize the ZVS for the lagging arm. The circuit reduces the switching wastage efficiently and improves the efficiency of power. A new drive circuit for IGBT is designed. It features high switching frequency, high driving power, simple-structure and reverse-turn-off.The technique of paralleling current sharing of switching power is introduced; the small signal model of the single DC/DC module and the multi-module is analyzed. The current-sharing controller UC3907 is adopted to design the current-sharing circuit for power supply, it can realize parallel multi-module to compose power supply system much more huge than one module.Finally, experimental results of the prototype are presented in the paper and the results of paralleling operation for two-power supply are presented.