Optimal Carrier Phase-shift Angle on Dual Three-Phase Windings Permanent Magnet Synchronous Motor

In this paper, we investigate the optimal carrier phase-shift angle to reduce harmonic loss under various operating conditions, such as torque, speed, DC voltage, and carrier frequency, on a dual three-phase-winding permanent magnet synchronous motor. We calculate the carrier harmonic voltage by theoretical analysis and relate it to the modulation depth in the torque-speed property. The carrier harmonic impedance behaviors are revealed in terms of the linkage magnetic flux of the first and second windings with the carrier phase-shift angle. By using the calculated carrier harmonic voltage and impedance, we reveal and verify the optimal carrier phase-shift angle of a phase-shift pulse width modulation to reduce the harmonic loss on a dual three-phase motor by comparison with measured results under variable torque-speed properties.