混合不对称多电平高压变频器输出共模电压及抑制方法

Common-mode Voltage of Hybrid Multilevel High Voltage Inverter and Its Cancellation Technology

在高压大功率变频器应用中,共模电压问题是必须考虑的因素,它将影响到系统的可靠性运行。多电平变频器输出共模电压的分析与抑制技术,近年来一直是研究的热点,但目前还没有文献对混合不对称多电平变频器的输出共模电压进行分析。因此对采用混合调制策略的混合不对称多电平变频器的输出共模电压进行了研究,分析了高低压单元对共模电压的不同影响。并在此基础上提出了部分共模电压抑制控制策略,可以有效地消除共模电压中的高频低压成份。最后通过仿真和试验验证了这种方法的可行性与正确性。

Common-mode voltage must be taken into account when inverters are designed and used because it will influence the system reliability. Consequently, the common-mode voltage of hybrid asymmetrical multilevel inverter was analyzed with deferent PWM modulation methods. Based on analysis of the different influences on the commonmode voltage of high and low voltage cells, a partial elimination technology to eliminate common-mode voltage was proposed. The new modulation method can eliminate the high frequency and low voltage part of common-mode voltage. Meanwhile, simulations and tests are carried out to verify the feasibility and validity.