Common-mode voltage elimination of multilevel converters with reduced switching loss using sawtooth-carrier-based PWM

Abstract

This article proposes an asymmetrical switching pattern to eliminate common-mode voltage (CMV) in multilevel converters while reducing switching loss by rearranging the switching sequence to minimize the number of level-shifts. In contrast to the existing symmetrical switching pattern, this approach achieves CMV elimination without increasing switching loss. To implement this asymmetrical switching pattern, a simple sawtooth-carrier-based pulsewidth modulation scheme is proposed that avoids the need for complicated space vector modulation computation, particularly for high-level converters. The proposed method's effectiveness is demonstrated through simulations and experimental results for the three-phase cascaded H-bridge converter and boost seven-level active neutral-point-clamped converter.