Second Order Radial Force Suppression Method with Harmonic Current for Double-star Permanent Magnet Synchronous Motors

Abstract

Automotive motors are necessary to reduce vibrations and improve reliability. Double-star permanent-magnet synchronous motors (PMSMs) improved reliability however, they generate a radial force, causing vibrations similar to those of conventional three-phase PMSMs. This study introduces a radial force suppression method using a double-star PMSM which increases the degrees of freedom of synchronous frames from two to four, and two redundant degrees of freedom. Superimposing harmonic currents on the redundant degrees of freedom suppresses the radial force. The performance of the proposed suppression scheme is evaluated using finite element analysis and experimental results. The scheme targets the generated second-order component, which is larger than the other order components. The results indicate that harmonic current can suppress the second-order radial force and second-order radial acceleration on the stator core. Superimposing the harmonic current suppresses the second-order radial acceleration from 0.0865 to 0.0082 m/s2, and the suppression effect is 90.5%.