Leading and lagging power factor operations of a four-quadrant AC-DC converter with sinusoidal line currents

This paper presents the lagging and leading power factor operations, with near sinusoidal line currents, of the bidirectional buck-boost type improved power quality (IPQC) ac-dc converter that employs power MOSFET embedded four quadrant switches (4QSWs). The topology of the IPQC itself ensures variable bi-directional dc voltage and reversible current in both buck and boost modes, however, application of the hysteresis current control based closed loop technique renders operation of the converter in either mode at any power factor, in any quadrant, with almost sinusoidal currents at the utility interface by appropriately modifying the switching pattern of the 4QSWs. The control strategy is evaluated for the IPQC by simulations implemented in the single and three phase topologies of the converter. Results pertaining to leading and lagging power factor operations in both modes for the four quadrants are presented.