Expansion of Field-Oriented Control Operation Range of Dual Three-Phase Synchronous Motor with Flux Weakening Control in the Inverter Overmodulation Region

As the theories for expanding the operation range, the inverter overmodulation strategy and the flux weakening control method are widely used on the three-phase motors. In conventional research, it was found that a dual three-phase motor can be field-oriented-controlled in the overmodulation region easier than a three-phase motor. In this study, the theory of utilizing the flux weakening control and inverter overmodulation together for Dual Three-Phase Synchronous Motor is proposed, and the current reference calculation method under the flux weakening control is presented. The expansion performance of the proposed field-oriented control operation range is evaluated.

I. Introduction

As competitive alternatives to the conventional three-phase motors, multiphase motors have been researched and developed to achieve high output with low voltage and high current, as well as to ensure reliability against faults, and have been practically applied in applications such as electric power steering, ship elevators, and wind power generation [1]. Additionally, multiphase motors are known to offer advantages over three-phase motors in terms of reducing torque ripple and increasing control flexibility [2]–[4]. One known control method for multiphase motors is Vector Space Decomposition (VSD) control [5], which decomposes fundamental and harmonic components and independently controls them. This allows multiphase motors to be controlled similar to field-oriented-controlled three-phase motors.