级联型多电平逆变器的功率均衡控制策略

Power Balance Control Schemes for Cascaded Multilevel Inverters

该文针对级联型多电平逆变器的几种调制方法,包括阶梯波调制法、特定谐波消除脉宽调制法和载波空间排列SPWM法,提出了一种新的功率均衡控制策略。该策略利用级联型多电平逆变器相电压冗余的特点,通过以1/4输出周期为单位互换各个H桥单元的输出电压波形,实现了各个H桥单元在一个输出周期内的功率均衡。与现有的功率均衡策略相比,新的策略可以在一个输出周期内达到功率均衡,并具有控制简单,H桥单元功率波动小的优点,同时满足对效率和波形的要求。该文以三单元七电平级联型逆变器为例,对上述功率均衡控制策略进行了理论分析和仿真验证。

A new power balance control schemes for the modulation strategies of cascaded multilevel inverter, including staircase strategies, selective harmonic elimination strategies and carder disposition SPWM strategies, is proposed in this paper. The new schemes ensure the output power balance in one output cycle through interchanging output voltage of the H-bridge cells according to quarter cycle with appending restricting equations by use of redundant phase voltages. Compared with conventional schemes, the new schemes can balance power in one output cycle, and are easy to be implemented and have low power fluctuation, meanwhile the THD of the output voltage is very small. A seven-level cascaded inverter composed by three H-bridge cells is taken as the example, and the new schemes are researched and simulated in this paper.