Partly Isolated Symmetrical Six-Phase Induction Motor Drive System Based on Conventional Three-Phase Transformer

The drive of multi-phase induction motors is usually done using multi-phase inverters. Due to the increase of power switches in multi-phase inverters, the cost and complexity of the drive system increase. This article proposes a simple power circuit to drive a six-phase induction motor. This power circuit consists of a typical three-phase inverter and a three-phase transformer. In this system, the three-phase transformer has half the rated power of the motor, which reduces the weight and cost of the system. Also, the two three-phase systems that make up the six-phase system are entirely isolated. Neutral point isolation of two three-phase systems will eliminate zero sequence currents. In addition to the complete description of the proposed system, its simulation and experimental results are also presented. Simulation of speed control based on the constant volt-hertz method for this system has been done in MATLAB Simulink software. Sinusoidal pulse width modulation (SPWM) scheme is used to produce the switching pattern of the conventional three-phase inverter, which makes the phase currents have low total harmonic distortion (THD).