One Active State Excitation for Saliency-based Encoderless Control of Dual Motors Supplied by a Single Inverter

Abstract

The extraction of motor spatial saliencies permits stable control at standstill and nearby speeds. One technique to extract saliencies is to excite the motor with voltage steps and process the resulting phase current slopes to form a saliency vector. Yet, the additional voltage steps produce unwanted current ripple and increase audible noise. Therefore, voltage steps have been recently integrated into the space vector PWM symmetrical switching scheme, defined at each period by two adjacent active states and two inactive states. In this paper, only the longest active state is used for saliency extraction. The novelty of this paper lies in the application of the one-active SVPWM excitation to a parallel dual motor configuration supplied by a single inverter and using a reduced current sensor configuration. This configuration consists of only three current sensors, two sensors attached to two phases of one motor, and a single sensor attached to the second motor. A novel signal processing scheme is presented in this paper to extract the saliencies of each motor individually under one-active SVPWM excitation. Experimental results demonstrate the ability of the proposed technique for dual motor saliency extraction under one-active space vector PWM excitation and using the special current sensor configuration.