A Novel Unipolar Pulse-Width Modulation Scheme for Single-Phase H-Bridge Inverters With Balanced Switch Loss Distribution

This paper introduces a novel unipolar pulse-width modulation (PWM) strategy for single-phase 4-switch H-bridge inverters, designed to enhance power efficiency, thermal balance, and device reliability without necessitating hardware modifications. The proposed strategy maintains the output voltage waveform while achieving total power losses significantly lower than the conventional unipolar PWM approach. Another key contribution of the proposed scheme is the even distribution of power losses across all four switches, resulting in balanced junction temperatures of 80°C. This thermal uniformity enhances device longevity and mitigates the need for dedicated cooling of overstressed switches, addressing a critical limitation in existing schemes. Furthermore, the proposed method preserves the favorable harmonic performance (low total harmonic distortion (THD)) of the modified conventional unipolar PWM scheme, avoiding the introduction of low-order harmonics common in alternative techniques.