Current Control of a High Power Factor Improved Power Quality Four Quadrant AC-DC Converter

This paper presents the application of hysteresis current control to the bi-directional buck-boost type improved power quality (IPQC) ac-dc converter that employs power MOSFET based four quadrant switches (4QSWs). The converter, capable of buck and boost modes of operation, outputs variable bidirectional dc voltage and reversible current in both modes. The control strategy is evaluated for the bi-directional buck-boost IPQC by simulations implemented in the single-phase and three-phase topologies of the converter. The simulation results confirm the efficacy of the hysteresis control that renders operation of the converter in either mode in any of the four quadrants and at any power factor with almost sinusoidal current at the utility interface by appropriately modifying the switching pattern. Results of bilateral power transfer in both modes at almost unity power factor are presented.