A Reactive Voltage Compensation-Based Control Scheme to Extend Speed Range in Five Phase Open-End Winding Induction Motor Drives

A reactive voltage compensation based control scheme for extending the speed range in dual inverter-fed five phase induction motor drives with open-end stator windings is proposed in this paper. In the dual inverter-fed five phase drive topology used to implement the proposed control scheme, one inverter is powered from a DC source while a charged capacitor acts as the DC-link of the other inverter. Since the control scheme is developed by considering the motor current vector as the reference, the motor voltage can be resolved into its active and reactive components. The capacitor-fed inverter is controlled in such a way that it compensates the increasing reactive voltage drop inside the motor as the speed increases, thereby extending the constant power speed region of the drive. The scheme also ensures that the voltage across the capacitor is maintained at the required level, under all operating conditions of the drive. This feature also safeguards the capacitor against overcharging. In addition, the auxiliary plane harmonics generated by both inverters are nullified in an average sense, in a switching period. The proposed control scheme is substantially simpler compared to the existing schemes, due to the unified PWM scheme and reduction in PI controllers. The experimental validation of the proposed scheme is carried out on an open-end winding induction motor under transient as well as steady state operating conditions. TMS320F28335 DSP based digital controller is used for implementation of the control algorithm.