Novel carrier-based PWM methods for multilevel inverter

The paper presents the idea of control degrees of freedom combination. Two novel carrier-based multilevel PWM methods are presented which take advantage of multiple control degrees of freedom available in multilevel inverters. The idea of control degrees of freedom combination and the validity of the PWM strategies are demonstrated by simulation and experimentation of a three-level inverter and a five-level inverter. The simulation and experimentation results indicate that the idea of control degrees of freedom combination is an important clue to realize the high performance multilevel inverter and the two PWM strategies exhibit the good harmonic characteristics or higher DC bus utilization than conventional PWM methods.