This paper investigates a method of reducing the vibration property of a permanent-magnet synchronous motor (PMSM) with dual three-phase windings, especially focusing on carrier harmonics. Electromagnetic excitation force on carrier harmonics, which makes carrier harmonic vibration, is formulated and the relationship of the carrier phase difference between the space and the time phase difference to cancel out the excitation force is calculated for dual three-phase winding PMSM. Then, the carrier phase shift space vector pulse width modulation (SVPWM), which makes any difference between the PWM carrier phase of the first and second windings, is applied to 24-slot 20-pole PMSM. A test motor is manufactured and measured results reveal that the vibration and sound pressure can be approximately halved at around carrier harmonic and twice carrier harmonic when the carrier phase is π/2 radian compared to conventional in-phase carrier PWM.
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