Harmonic-Injection Based Noise Reduction of Interior Permanent Magnet Synchronous Motors for Electric Vehicles

This paper proposes a harmonic injection method to improve vibration and noise behaviors of interior permanent magnet synchronous motors (IPMSMs) for electric vehicles (EVs), which reduce the oscillation of magnetic field forces and can particularly reduce the zeroth order force that are known for their major influence on the noises of traction drives. The optimum amplitude and phase of injected current harmonics have been first deduced. Then, a coordinate transformation and a low-pass filter are employed to detect the harmonic orders of the current, and a harmonic current loop is incorporated into the original control system to implement the harmonic current injection(HCI) strategy. Finally, the effectiveness of the proposed method is validated by the experimental results. The sound pressure level of the 48-slots/8-poles IPMSM is reduced approximately 20 dB(A) through $5^{\text{t}\text{h}}$ and $11^{\text{t}\text{h}}$ order current harmonic injection with optimal amplitude and phase angle.