Zero-Sequence Current Mitigation Using a Virtual Voltage Vector Solution for MPC in Symmetrical Six-Phase Electric Drives With Single-Star and Hexagon Winding Configurations

Abstract

The increasing demand for advanced electric drives in applications, such as electric vehicles (EVs) and wind energy systems, has highlighted the advantages of multiphase machines, which offer improved power efficiency and reliability. Six-phase machines, especially symmetrical six-phase induction machines (S6PIMs), are gaining attention for their enhanced fault tolerance (FT) and compatibility with standard three-phase converters. However, their adoption is limited by the lack of more sophisticated current control strategies. Model predictive control (MPC) is favored for its dynamic performance. However, it faces many challenges, including high computational burden, current harmonic distortion, and zero-sequence currents. This study introduces a new approach integrating virtual voltage vectors (VVVs) into the MPC framework to specifically target zero-sequence currents and improve flux/torque generation, particularly in single-star and hexagon stator configurations within S6PIMs. Additionally, a novel symmetrical pulse width modulation (PWM) pattern is introduced to reduce the switching and to allow the use of fixed frequency. The effectiveness of the proposed method is demonstrated by experimental data.