Hybrid phase-shifted modulation method for hybrid cascaded H-bridge inverters

Due to its unreasonable DC voltage distribution, the phase-shifted pulse width modulation (PS-PWM) method cannot be directly applied to equal-ratio and equal-difference hybrid CHB inverters. Thus, these types of inverters lose the double-frequency characteristic of the CHB topology. To preserve this double-frequency characteristic, reduce the switching frequency of the high-voltage cells, and simplify the modulation method. This article proposes an optimized topology for the hybrid CHB inverter by optimizing the distribution of the DC voltage. A hybrid PS-PWM method is also proposed by combing the step-wave modulation method and the PS-PWM method. Theoretical analysis, simulation analysis, and experimental results show that the optimized topology and the hybrid PS-PWM method are both valid and feasible.