Design and Validation of a Robust Single-Phase AC-AC Chopper with Grounded Load

This project focuses on the design, analysis, and validation of a robust single-phase AC-AC chopper topology specifically engineered for compact and high-efficiency power conversion applications. The proposed converter architecture integrates distinct P-type and N-type AC switching-cell legs, which collectively facilitate comprehensive four-quadrant operation. A key advantage of this configuration is its inherent immunity to shoot-through conditions, enhancing operational reliability and reducing component stress. The switching legs are interfaced with a grounded load through a coupled inductor, forming a critical component of the power stage. A sophisticated three-step switching strategy is implemented, which significantly contributes to the topology's robustness. This strategy enables the converter to tolerate supply voltage polarity detection errors

within a substantial range of at least ±20° around the mains zero-crossing, thereby eliminating the necessity for large, bulky snubber circuits typically required in conventional designs. Furthermore, the project involves the application of an analytical methodology for precise sizing of the current-limiting inductors, meticulously accounting for the impact of circuit parasitics to optimize performance. The design principles are rigorously validated through detailed SPICE simulations and empirical measurements obtained from a 1.5 kW GaN-based prototype. Experimental results demonstrate superior performance characteristics, including low output voltage total harmonic distortion and high operational robustness, affirming the converter's suitability for demanding, space-constrained, and high-performance AC-AC conversion scenarios.

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