PWM with Non-Triangular Discontinuous Carriers for Modular Multilevel Converters

This paper introduces a PWM with phase-shifted non-triangular discontinuous carriers, suitable for low-voltage modular multilevel converters. It aims to reduce the harmonic distortion of the AC current and increase its RMS value. A harmonic analysis of the proposed modulation is carried out and compared with conventional PWM techniques. Its effectiveness is then experimentally validated using a 1.5 kW single-phase prototype, tested for both low and high arm inductance values. Across the evaluated modulation index range, the proposed PWM achieves up to a 67% reduction in AC current total harmonic distortion (THD), and a 62% increase in AC power, both relative to conventional PWM techniques.