A Speed Range Extension Scheme for Scalar-controlled Open-end Winding Induction Motor Drives

Abstract

This paper presents a new control scheme for extension of speed range of an open-end winding induction motor drives fed by two inverters. The inverter which is attached to one end of the open-end winding is fed by a DC power source whereas the inverter attached to the other end is fed by a capacitor. The control scheme ensures that only the active power requirement of the drive is met by the inverter fed by DC power source and the reactive power solely is provided by the capacitor fed inverter. The modulation index of the capacitor fed inverter is varied to provide higher voltage to the motor at higher speeds keeping the capacitor voltage constant, thereby facilitating operation above base speed without field weakening. The proposed scheme, based on constant v/f ratio control, is simple compared to the existing schemes. Validation of the proposed scheme is done under transient and steady state operating conditions by extensive simulation using PLECS software.