Selected Harmonic Mitigation PWM Power Matching Control Strategy for Asymmetric Cascaded H-Bridge Multilevel Inverter

In order to suppress high-order harmonics to meet the requirements of power quality standards and solve the power mismatching problem of asymmetric multilevel inverter, an improved power matching control strategy of asymmetric selected harmonic mitigation pulse width modulation (ASHM-PWM) is proposed in this article. This strategy is based on asymmetric dc-link voltage applied asymmetric cascaded H-bridge (ACHB) multilevel inverter. First, a new harmonic mitigation model based on the power matching control is proposed and the output active power of each H-bridge cell is analyzed theoretically. Second, switching angles are obtained by transforming multiobjective inequality problems of ASHM-PWM into single objective equation groups combined with improved particle swarm optimization (IPSO), which can simplify the solving process. Finally, the simulation model and experimental platform of ACHB multilevel inverter have been implemented to verify the ASHM-PWM power matching control strategy proposed in this article. The result shows that each H-bridge cell of ACHB can have power matching performance by meeting the power match of 1:k1:k2 in one cycle. Meanwhile, the total harmonic distortion (THD) of the output line-line voltage is reduced and the performance of harmonic mitigation is better.