An Edge-Aligned Modulation Technique to Suppress Leakage Current in the Back-to-Back Neutral-Point Clamped Converter

This article investigates the effect of the leakage current on the back-to-back neutral-point clamped (BTBNPC) converter. The analysis indicates the leakage current of the BTBNPC converter is closely associated with the difference of the common-mode voltage (CMV) between the rectifier and the inverter, so an equivalent model for the leakage current is derived to explore their relationship. Subsequently, an edge-aligned pulsewidth modulation (EAPWM) technique is presented to eliminate the CMV of the BTBNPC converter. This article also shows how to coordinate the rectifier and the inverter to develop the full potential of this circuit. Laboratory test results will verify the effectiveness of the proposed technique.