Efficient sequential switching hybrid modulation techniques for multiphase multilevel inverters

This study presents certain sequential switching hybrid modulation strategies, and compared for multiphase multilevel inverters. Hybrid modulation represents the combination of fundamental frequency, and multilevel sinusoidal modulations and designed for performance of the well-known alternative phase opposition disposition, phase shifted carrier, carrier-based space vector modulation and single-carrier sinusoidal modulations. The main characteristic of these modulations are the reduction of switching losses with good harmonic performance. A simple sequential switching and base pulse-width modulation (PWM) circulation techniques are embedded with these modulations, to achieve balanced power dissipation among the devices within a cell and for series connected cells, equal load sharing and balanced DC-link capacitor voltages. Multilevel sinusoidal PWM and its base modulation design are implemented on a TMS320F2407 digital signal processor (DSP). Complex programmable logic device realises hybrid control algorithm with base PWM circulation and integrated with DSP for sequential switching hybrid PWM generation. The feasibility of these modulations are theoretically analysed for five-level and then generalised for N-level, validated by simulation and confirmed practically for a five-level inverter.