Hysteresis-band current control of a four quadrant AC-DC converter giving IEEE 519 compliant performance at any power factor

This paper presents unity, lagging and leading power factor operations, with near sinusoidal line currents, of the bi-directional buck-boost type improved power quality ac-dc converter (IPQC) 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-band current control based closed loop technique renders operation of the converter in either mode at any power factor, in any quadrant, with a harmonic profile at the utility interface conforming to the IEEE 519 stipulations 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 confirm that the technique confers IEEE 519 compliance on the converter with regard to the Total Harmonic Distortion (THD), and, are presented for unity, leading and lagging power factor operations in both modes for the four quadrants.