级联多电平逆变器SHEPWM功率均衡控制策略

RESEARCH ON POWER BALANCE CONTROL SCHEMES OF CASCADED MULTILEVEL INVERTERS BASED ON SELECTIVE HARMONIC ELIMINATION PWM STRATEGIES

针对级联多电平(cascaded H-bridge,CHB)逆变器特定谐波消除脉宽调制法,提出一种功率均衡控制策略。该策略利用CHB逆变器相电压有冗余的特点,对消谐方程组中基波幅值方程表达式进行等效拆分,从而保证一相中各串联H桥单元输出基波幅值相等的1/4周期对称的电压波形,实现各串联H桥单元在一个输出周期内的功率均衡。以两单元级联五电平CHB逆变器拓扑为例,对上述功率均衡控制策略进行理论分析、仿真验证和实验验证。研究结果验证了该均衡策略的正确性和可行性。

A power balance control scheme for the selective harmonic elimination PWM strategies of cascaded multilevel inverter was proposed in this paper. The scheme achieves the output power balance in one output cycle through splitting the fundamental voltage amplitude equation expression of harmonic elimination equations equivalently by use of redundant phase voltages, which ensures the fundamental voltage generated by each H-Bridge in one phase is equal and the voltage waveform is quarter cycle symmetry. A five-level cascaded inverter composed by two H-bridge cells was taken as the examples, and the new schemes were researched and simulated. Experimental results verify the validity of the proposed strategy.