混合多电平逆变器拓扑及调制方法

Topology and modulation of asymmetrical hybrid multilevel inverter

针对传统多电平逆变器需要的开关器件数量较多,输出电压谐波较大等问题,该文提出了一种非对称混合多电平逆变器拓扑,包括二极管钳位非对称多电平逆变器和电压源串并联状态切换的H桥多电平逆变器。在输出电压电平数相同的情况下,该逆变器拓扑能减少开关器件的数量。采用与混合多电平逆变器相适应的混合调制控制策略,该策略使大部分开关器件工作在低频状态,减少了开关损耗,避免了电流倒流,降低了输出电压的总谐波失真(THD),可以实现连续PWM调幅。通过仿真,验证了该逆变器拓扑及其调制策略的正确性。

A novel topology,referred to as asymmetrical hybrid multilevel inverter topology,was developed to solve the problems of enormous number of switching devices and low quality of output voltage of conventional multilevel inverter.It consists of asymmetrical multilevel inverter with clamped diodes and H-bridge multilevel inverter with the voltage source switchover between series state and parallel state.Under the same voltage levels,the number of switching devices reduced.The paper also presented a new modulation strategy,by which the most of switching devices can work at low frequency,the current backflow can be avoided with reduced switching loss and total harmonic distortion （THD） of output voltage,and then the amplitude modulation of continuous PWM can be realized.The validity of the proposed topology and control method was verified by simulation results.