Highly Efficient Single-Phase Buck-Boost Variable-Frequency AC-AC Converter With Inherent Commutation Capability

This paper introduces a novel single-phase buck-boost noninverting variable-frequency ac-ac converter that offers higher efficiency compared to the competitors. This converter utilizes a lower number of semiconductors. A simple and flexible switching strategy is also proposed, which generates the desired output waveform avoiding unnecessary high-frequency switching operation of semiconductor devices. A high reliable operation due to the elimination of the input source shoot-through risk, an inherent commutation capability that mitigates the voltage spikes across the semiconductors, a lower semiconductors rating requirement, an improved input current waveform quality, and a smaller required input filter inductor are the main advantages of the proposed converter. Thus, the proposed converter can be successfully applied to many industrial applications such as medium-frequency transformer isolation for traction and wind turbine converters, ac-dc high-voltage conversion based on Cockcroft-Walton circuit and induction heating systems. The theoretical achievements and claims are all confirmed through extensive experimental tests on a 200-W laboratory setup.