级联型逆变器载波循环功率均衡控制方法及比较

Power Balance Control Methods and Comparative Study Using Carrier Rotation Technique for the Cascaded Inverter

在级联H桥型逆变器中,载波同相层叠(PD)调制策略虽然输出线电压具有最优的谐波特性,但无法实现级联单元间输出功率均衡。针对这个问题,提出两种基于PD调制策略的载波循环功率均衡控制方法,所提方法在改进型PD调制策略的基础上,通过对载波进行周期性的循环移动,可以有效实现级联单元间的功率均衡控制,且保留了PD调制策略下逆变器输出电压谐波特性最优的特点。以三单元级联H桥逆变器为例,首先对改进型PD调制策略下级联单元输出功率特性进行数学推导;其次分析两种所提功率均衡控制方法实现机理并对其特性进行比较,揭示两种功率均衡控制方法的优缺点以及适用场合。最后通过仿真和实验结果验证了理论分析的正确性与所提方法的可行性。

For cascaded H-bridge inverter,phase disposition(PD)modulation strategy fails to achieve power balance among cascaded cells,although the output line voltage has optimal harmonic performance.In order to solve this problem,two kinds of power balance control methods using carrier rotation technique based on PD modulation strategy were proposed.Through carrier periodic rotation,the proposed methods could effectively realize the power balance control among the cascaded cells and retain the same harmonic characteristics of the output voltage under the PD modulation strategy.Three-cell cascaded H-bridge inverter was taken as an example.Firstly,the output power characteristics of the cascaded cells were deduced under the modified PD modulation strategy.Secondly,the mechanism of the proposed methods was analyzed and their characteristics were compared.Hence,the advantages and the applications of the two power balance control methods were revealed.Finally,simulation and experimental results verified the proposed methods.