Simple Voltage Modulation Technique for Quasi Six-Phase Series Connected Two-Motor Drive System

Several proposals on multi-phase multi-motor drive systems are given in the literature. This paper focuses on one such configuration with stator windings of two quasi six-phase machines (two set of stator windings with 30 degrees phase displacement) connected in series and supplied from a single six-phase voltage source inverter, forming two-motor drive structure. A simple voltage modulation technique is described for six-phase voltage source inverter feeding such motor drive configuration. The proposed modulation is based on the sampled reference voltages and effective time concept. In the proposed technique the actual switching times for each inverter legs are obtained directly in simple form. The execution time in real time application can be reduced significantly compared to the conventional space vector pulse width modulation (SVPWM). Simulation and experimental results are provided to validate the proposed theory.