Tangential Force Noise Reduction of Vehicular PMSM Based on Reference Harmonic Current Analytical Computation

The harmonic current injection (HCI) can remarkably reduce the noise of the vehicular electric drive system. However, the optimal reference harmonic current is difficult to obtain because of the vehicular motor’s nonlinear electromagnetic characteristics. The existing methods are always time-consuming and cannot satisfy the real-time requirement of the vehicular application. This article proposed an analytical computation method of the reference harmonic current for tangential force noise reduction. Specifically, by combining 2-D Fourier series decomposition and polynomial fitting, a data-based nonlinear model is constructed to accurately describe the tangential force harmonic under arbitrary current excitation. Then, considering the dominant effect of fundamental current, a simplified tangential force model is obtained by local linearization at each fundamental current working point. Meanwhile, by representing the stator current amplitude with a Fourier series combination, the suppression of tangential force harmonics is transferred to solving linear equations concerning each harmonic current vector. Finally, simulation and bench test experiments have been done to verify the effectiveness of the proposed method. The results demonstrate that the reference harmonic current at different speeds/torque can be computed in real time, and the corresponding tangential noise can be reduced remarkably.