A Novel PWM Control Method for Hybrid-Clamped Multilevel Inverters

A novel pulsewidth modulation (PWM) control method is proposed in this paper. The PWM control method is called higher and lower carrier cells alternative phase opposition PWM (HLCCAPOPWM) for the hybrid-clamped multilevel inverter and based on the improvement of carrier phase disposition PWM (PDPWM). The principle of the HLCCAPOPWM method, the comparison with the carrier PDPWM method, and the analysis on output voltage spectrum are given. Simulations and experiments show that comparing with the carrier PDPWM method, the novel method can effectively reduce the number of devices switching on or off within broad modulation index range, consequently reducing switching losses, and remarkably reduce the amplitude of lower harmonics. Simulations also show the generalization of the HLCCAPOPWM method for hybrid-clamped n-level inverters and neutral-point-clamped inverters.