级联多电平逆变器功率均衡控制策略研究

摘要

针对级联型多电平逆变器(CMI)特定谐波消除脉宽调制(SHEPWM)存在的功率均衡问题,提出了一种新型功率均衡控制策略.该策略利用CMI相电压冗余的特点,对消谐方程组中基波幅值方程表达式进行等效拆分,从而保证每相中各个串联H桥单元输出基波幅值相等且1/4周期对称的电压波形,实现各个串联H桥单元在一个输出周期内的功率均衡.以两单元五电平级联逆变器为例,对上述功率均衡控制策略进行了理论分析和仿真验证.实验结果验证了该均衡策略的可行性.%A new power balance control scheme for selective harmonic elimination pulse width modulation (SHEPWM) strategy of cascaded multilevel inverter(CMI) is proposed.The new scheme achieves the output power balance in one output cycle through splitting the fundamental voltage amplitude equation expression of harmonic elimination equations equivalently by the use of redundant phase voltages,which ensures the fundamental voltage generated by each Hbridge in one phase is equal and the voltage waveform is quarter cycle symmetry.A five-level cascaded inverter composed by two H-bridge cells is taken as the example,and the new schemes are researched and simulated.Experimental results verify the validity of the proposed strategy.