PWM Algorithm for Dual Three-Phase PMSM with Open-Delta Winding Structure

To address the challenge of deep field-weakening in traditional permanent magnet synchronous motors (PMSMs), the third-harmonic-magnetic-field-based pole-change PMSMs has been proposed. The rotor's permanent magnets generate both a fundamental magnetic field and a significant third harmonic field, while the stator employs two sets of three-phase open-delta windings with a 30° phase shift. Due to the unique stator winding structure and the substantial third harmonic component in the rotor's magnetic field, large third harmonic currents are induced in the windings, causing additional copper losses. This paper presents two new six-phase PWM modulation algorithms and an Equally Amplitude Staircase Injection Modulation (EASIM) method to counteract the third harmonic currents. The proposed solutions are validated through simulations, confirming their correctness and effectiveness.