一种PWM软开关变流器实现及损耗分析

PWM Soft Switch Inverter and Loss Analysis

零电流转换(ZCT)技术通过控制辅助电路的谐振,为开关器件创造零电流的开关条件。辅助电路的引入不会对主电路的控制算法产生影响,使得传统PWM控制策略能够直接应用在软开关变流器上。在分析ZCT软开关工作原理的基础上,引入的辅助电路损耗小于减少的开关损耗,ZCT技术提高变流器的整机效率。通过一台500 kVA三相ZCT软开关PWM软开关变流器互馈试验平台,完成了功率、软开关试验及不同谐振参数下的效率对比试验。试验结果表明,PWM变流器基本实现了开关器件的零电流转换,且谐振过程与理论分析基本相同,验证了谐振电流峰值与谐振周期对整机效率的影响。

The zero current transition （ZCT） technique creates the switch conditions for zero currents by controlling the auxiliary circuit resonance. The auxiliary circuit did not influence on the traditional PWM strategy for the soft switch converter. With the principle of the ZCT soft switch, the PWM converter worked in a higher switching frequency, which improved the performance of the converter. As long as the extra losses of the auxiliary circuit were less than the reduced switching losses, PWM converter raised the efficiency. A 500 kVA ZCT soft switching converter prototype was built. The power experiment, soft switch experiment and efficiency contrast experiment at different parameters were carried out. The experimental results show the ZCT of power electronic devices is achieved, and the resonant process is consistent with the theoretical analysis. The relations of converter efficiency, resonant peak current and resonant period are verified.