一种不对称级联H桥多电平逆变器通用的线性功率均衡方案

One general linear power equalization scheme for asymmetric cascaded H-bridge multilevel inverters

不对称级联H桥多电平逆变器由于级联各个单元的直流侧电源电压不同,出现级联单元之间功率分配不均衡问题,为此提出一种通用的线性功率均衡调制方案。功率均衡调制方案对高压单元导通角进行约束,对低压单元的载波进行纵向循环重构,实现了各个级联单元直流侧电源电压不同的情况下,使得逆变器可以在全调制度下保持各级联单元输出功率均衡的效果。并且在拓扑结构增加级联单元数时,调制策略也展现出优秀的通用性。同时该方案对低压单元进行的载波重构还能够使得各低压单元的开关管损耗保持一致,使各个H桥的开关管具有更为接近的温升,有利于逆变器选择合适的散热器。最后通过仿真与实验证明了方案的有效性。

In order to solve the problem of unbalanced power distribution between cascade units due to the different DC-side power supply voltages of each cascaded unit of asymmetric cascaded H-bridge multilevel inverter,a general linear power equalization modulation scheme was proposed.By constraining the con-duction angle of the high-voltage unit and the modulation strategy of longitudinal cyclic reconstruction of the carrier of the low-voltage unit,in the power equalization modulation scheme the effect was realized that the inverter can maintain the output power balance of the linkage units at all levels under the full modulation system when the power supply voltage on the DC side of each cascade unit is different.And when the number of cascading elements is increased in the topology,the modulation strategy also shows excellent versatility.At the same time,the carrier reconstruction of the low-voltage unit in this scheme can also make the switch loss of each low-voltage unit consistent,so that the switch tube of each H-bridge has a closer temperature rise,which is conducive to the inverter to choose the appropriate radiator.Final-ly,effectiveness of the scheme was proved by simulation and experiment.