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A simple and efficient single-phase direct ac-to-ac converter with the possibility to be utilized as a voltage buck or buck–boost converter is proposed in this article. The proposed converter offers higher efficiency than the competitors with a lower number, of semiconductors. The proposed switching strategy minimizes the high-frequency operation and simultaneous conduction of semiconductors during each mode of operation. Besides a higher efficiency, the other major advantages of the proposed converter are eliminating the risk of input source shoot-through, a lower number, and total rating of semiconductors, defined by switching device power parameter, a lower number and smaller size of reactive components, a better input current quality, and lower filtering requirements. The theoretical claims are confirmed through experiments on a 480-W prototype built in a laboratory. [ABSTRACT FROM AUTHOR]

Two new power factor correction (PFC) rectifiers with the voltage buck-boost capability are proposed in this article, called as Ferdowsi rectifiers (FRs). The proposed rectifiers employ a reduced number of semiconductors compared to the competitors. Also, since the reverse recovery problem of antiparallel diodes of transistor switches is avoided, then MOSFETs can be readily utilized, which lets much higher switching frequencies and lower size of passive components. In addition, two parallel capacitors provide a path for the input current during the discharge mode of the buck-boost inductors to improve the current quality. The discontinuous conduction mode operation of the proposed rectifiers guarantees a high quality input current with a low total harmonic distortion. All aforementioned features offer a highly efficient operation and at the same time a purely sinusoidal current drawn from the ac source compared to the previous well-developed competitors. The validation of the theoretical achievements is performed by extensive tests on a laboratory test rig. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]