全桥ZVS PWM电容器充电变换器

Full Bridge ZVS PWM Capacitor Charging Converter

为对广泛应用的电容充电大功率全桥零电压软开关高压变换器进行理论分析,从零电压(相当输出短路)到最大电压用变换器对电容器进行了充放电试验。变换器电路中充分利用器件的寄生参数,通过在高压变压器的原线圈串联电感,实现主开关管输出高压整流二极管的零电流软切换,变换器通过脉宽调制和电流控制调节输出电压并具有过压和过流保护功能。给出变换器的静态分析,同时给出了基于UCC3895 PWM控制器的直流—直流变换器样机的详细设计和1 kJ/s充电速度的实验结果表明变换器的理论分析正确,方法可行。

For theoretically analyzing a full bridge zero voltage switched （FB-ZVS） pulse width modulation （PWM） capacitor charging converter, the repetitive capacitor charging operates from zero voltage （near short circuit） to maximum voltage in the high power high voltage pulse application, and it exhibits an excellent ability to incorporate parasitic parameters, zero voltage switching characteristics for all active switches and zero current switching operation for all diodes on the high voltage side. This result is accomplished by adding a choke in series with the primary side of the high voltage transformer. Based on the features of high-voltage high charging speed, the converter employs fixed frequency phase-shift control technology to implement soft-switching commutations. Pulse width modulation and current-controlled switching are applied to a full-bridge phase-shift converter to regulate the output voltage. The protection circuit can be easily included in the system and good regulation of charging voltage can be achieved by the feed back system. Steady-state analysis of the converter is presented and major features of the converter are discussed. The design detail based on UCC3895 phase shift PWM controller and test results of a prototype unit are presented. The experimental results obtaining from laboratory prototype rated to 1000J/s charging speed have verified the validity of the operation theory.