H桥多电平逆变器的新型调制

针对传统PD调制法应用在级联H桥多电平逆变器时存在的输出功率不均衡问题,提出一种基于1/4输出周期载波循环的优化调制策略,使得逆变器各级联单元的输出功率均衡,且开关管的最高开关频率降为原来的一半,降低了开关损耗.该优化调制策略比传统PD调制需要的三角载波数量更少,调制更简单.以四单元级联H桥多电平逆变器为例进行理论分析,并通过仿真实验验证了所提方法的正确性.

New modulation of H-bridge multi-level inverter

In order to solve the problem of output power imbalance when traditional PD modulation method is applied to cascaded H-bridge multilevel inverter, this paper proposes an optimal modulation strategy on the basis of 1/4 output period carrier cycle, which makes the output power of all levels of inverter balanced. The maximum switching frequency of a switch tube is reduced to 1/2 compared to original, thus reducing the switching loss as a result. The optimal modulation strategy proposed in this paper requires only less triangular carriers as well as simpler modulation than traditional PD modulation. The author takes a four-unit cascaded H-bridge multilevel inverter as an example for theoretical analysis, and the correctness of the proposed method has been verified by simulation experiments.