Independent active–reactive power control scheme for NSC-drive operated at constant frequency

Abstract

ABSTRACTThis paper presents a new control scheme for the ac-dc-ac nine-switch converter (NSC) with induction motor operated at constant frequency. The NSC at constant frequency operates optimally and its application for induction motor drive with re-active power compensation is proposed. In industries for various applications, induction motors are operated at constant frequency but at different loading conditions. These motors are operated at lagging power factor. The power distribution company demands high power factor operation and it gives benefits to consumer on operating a system closer to unity. In this paper, a control scheme is proposed to operate NSC drive at unity as well as at leading power factor with sinusoidal input current. The independent active–reactive power control technique is developed. The input–output active power relation is developed such that with the change in load, output active power matches input active power without affecting dc-link voltage. This results in faster dynamic response as compared to conventional dc-link balancing control techniques. With the proposed control scheme, the NSC is operated at desired leading power factor to compensate reactive power at point of common coupling. The simulation and experimental results show the feasibility of the proposed control scheme.