多电平SPWM变频器中共模电压抑制技术的研究

RESEARCH ON COMMON-MODE VOLTAGE REDUCTION IN MULTI-LEVEL INVERTER

鉴于两电平变频器输出的共模电压只能依靠外接滤波器进行消除,研究了三电平PWM变频器中共模电压的抑制技术。利用三电平变频器的有效开关状态,分析了三电平变频器中产生共模电压的原因,得出奇数电平变频器可以通过软件的方法来抑制共模电压的结论。针对常用的变频器控制策略—SPWM ,提出了降低和消除共模电压的改进策略,并用仿真结果验证了其正确性。文中还给出了不同的调制策略对电动机性能影响的比较,验证了所提策略的可用性。

PWM technology for common-mode voltage reduction in three-level inverter is investigated whereas common-mode voltage generated by two-level inverter can only be reduced by an additional filter. With effective on-off states in three level inverter, common-mode voltage generated by three-level inverter is analyzed, then a conclusion is gained that common-mode voltage can be reduced by using software in odd-level inverter. Reducing and canceling common-mode voltage methods are presented using SPWM (Sinusoidal Pulse Width Modulation). Simulation results validate their correctness. A comparison is also made among their effects on motor performance, and then usability of the proposed methods is analyzed.