Modified Discontinuous Modulation for Mitigating Distortions at Phase Clamping in Y-Converter

The three-phase Y-converter, when operated under discontinuous pulse-width modulation (DPWM), can achieve higher efficiency and power density compared to conventional sinusoidal modulation techniques. However, DPWM introduces waveform distortions during phase clamping intervals, adversely affecting the quality of the ac-side voltages and currents. This paper proposes a modified DPWM strategy that mitigates these distortions by shaping the common-mode voltage to ensure smooth transitions in the ac-side capacitor currents and voltages. The proposed modulation technique is broadly applicable to various Y-converter configurations, including single-phase and multiport variants. The effectiveness of the proposed strategy is validated through both simulation and experimental results, demonstrating significant improvements in waveform quality during clamping periods.