A high-gain symmetric-bipolar buck-boost AC-AC converter with step-changed output frequency and rectifier operation

This paper introduces a new single-phase non-isolated symmetric-bipolar buck-boost alternating current-alternating current (AC-AC) converter, along with its associated commutation method. The topology comprises five switches, which can be implemented using industrialized single- or dual-diode and Insulated Gate Bipolar Transistor (IGBT)/Metal Oxide Semiconductor Field-Effect Transistor (MOSFET) modules. The proposed buck-boost AC-AC converter inherits all the beneficial features of existing designs, including the ability to generate both inverted and non-inverted output voltages, provide continuous input current, and offer the capability to change the output voltage frequency in a stepwise manner, as well as rectify the output voltage. The proposed AC-AC converter can achieve a high output gain because a two-winding coupled inductor has been integrated into its converter structure. This way, the buck-boost coverage range of the topology can be adjusted by the appropriate selection of the winding ratio of the coupled-inductor. Compared to its counterparts, the proposed converter performs better in terms of voltage gain, switching device power (SDP), volumetric indices of inductors and capacitors, and efficiency. These features make the proposed converter suitable for traction systems and dynamic voltage restorer (DVR) applications. This article details the operating principle of the proposed topology and presents experimental results validating its performance as an AC voltage regulator and a DVR circuit.