电网电压畸变不平衡情况下三相PWM整流器无锁相环直流母线恒压控制策略

Constant DC Voltage Control Strategy for Three-phase PWM Rectifier Without Phase-locked Loop Under Distorted and Unbalanced Conditions

直流母线恒压控制是三相脉宽调制(pulse width modulation,PWM)整流器非理想电网电压情况下稳定运行的关键问题之一。首先建立三相PWM整流器的小信号模型,推导出直流母线电压的传递函数表达式;在此基础上分析电网电压畸变不平衡情况下直流侧波动的原因,进而提出一种无锁相环直流母线恒压控制方法;最后搭建系统硬件实验平台,在电网电压畸变和不平衡情况下对传统方案和提出的方案进行实验研究。实验结果验证了该方法的有效性。

Constant dc bus voltage control under distorted and unbalanced grid voltage conditions is one of the most important techniques for three-phase PWM rectifier. First of all, the small signal model of three-phase PWM rectifier was built, and the transfer function of the dc bus voltage was derived. The inherent reason of the dc voltage fluctuation was discussed based on the small signal model. Second, a new constant dc voltage control strategy for three-phase PWM rectifier without phase-locked loop was proposed. The experimental hardware platform was built, and the tests were carried out under the distorted and unbalanced grid voltage conditions. The experimental results verify the effectiveness of the proposed method.