Novel multilevel inverter carrier-based PWM method

The advent of the transformerless multilevel inverter topology has brought forth various pulsewidth modulation (PWM) schemes as a means to control the switching of the active devices in each of the multiple voltage levels in the inverter, An analysis of how existing multilevel carrier-based PWM affe cts switch utilization for the different levels of a diode-clamped inverter is conducted. Two novel carrier-based multilevel PWM schemes are presented which help to optimize or balance the switch utilization in multilevel inv erters. A 10-kW prototype six-level diode-clamped inverter has been built a nd controlled with the novel PWM strategies proposed in this paper to act a s a voltage-source inverter for a motor drive.