A Single-Phase AC Chopper with Grounded-Load and Robust Switching Strategy

Abstract

A robust single-phase AC–AC chopper topology with a grounded load is proposed for compact, high-efficiency power conversion. The converter comprises one P-type and one N-type AC switching-cell leg, enabling four-quadrant operation while simultaneously being inherently immune to shoot-through conditions. The legs are connected to a grounded load via a coupled inductor, and together with a three-step switching strategy, form a topology which is tolerant to supply voltage polarity detection errors of at least ±20° around the mains zero-crossing, without the need for large, bulky snubbers. An analytic method is presented for sizing the current-limiting inductors, which accounts for the effects of circuit parasitics. SPICE simulations and measurements from a 1.5 kW GaN-based prototype validate the design, demonstrating low output voltage THD and high robustness. The converter is suitable for space-constrained, high-performance AC–AC conversion applications.