This paper first derives the characteristics of radial electromagnetic force considering different types of current harmonics. By using two-dimensional fast Fourier transform, the force calculated by the finite element method is decomposed to obtain the frequencies of the force components in specific spatial order. Then, a multiphysics model for electromagnetic vibration and noise calculation is proposed. A modal test is implemented to validate the equivalent stator model and the nonuniform distribution of electromagnetic force acting on the teeth surface is taken into account through the nodal force transfer method. The calculated vibration and noise agree well with those obtained from experimental test. Finally, vibration and noise under different supply currents are investigated, and the variation patterns of the noise and vibration peaks are explained by the amplitude changes of the lowest spatial order force due to current harmonics. It is found that the influence of current harmonics on vibration and noise depends on their effect on the lowest spatial order force, and in order to figure out this effect, the phase angle, phase sequence, and frequency of current harmonics should all be considered.

Permanent magnet synchronous motors (PMSMs) have been widely used as the driving core in electric vehicles due to the high power/torque density and high efficiency. Recent years have witnessed a great effort on the vibration and noise of PMSMs in order to ensure the driving comfort. In this paper, the state of the art and recent progress of the electromagnetic vibration and noise of PMSMs for electric vehicles are presented, with emphasis on the induced mechanism, prediction method, suppression method and sound quality. The future trends faced are also described.

This paper presents a detailed analysis of the axial electromagnetic force and vibroacoustic behavior of the external-rotor axial-flux motors. First, the spatial and temporal characteristics of axial force acting on the surface of magnets are derived analytically and validated through the 2-D Fourier decomposition. Subsequently, a multiphysics model is established to calculate the vibration and noise of an external-rotor axial-flux in-wheel motor, which integrates the control model, the electromagnetic model, the structural model, and the acoustic radiation model and takes the uneven distribution of axial force into account. The accuracy of the multiphysics model is verified by the noise test. The vibroacoustic mechanism of axial-flux motors is revealed based on the multiphysics model, the influence of current harmonics and dead time effect on the vibration and noise are also analyzed. Finally, the main orders of tested noise are explained by the theoretical analysis. It is found that the zeroth spatial order axial force is dominant for the generation of the vibration and noise in axial-flux motors. The harmonic current may deteriorate the vibroacoustic behavior, but depending on its amplitude and phase. This study provides guidance for the design of low-noise axial-flux motors.

A multiphysics model is proposed to predict electromagnetic noise and analyze sound quality of permanent magnet synchronous motor with a variable speed range. First, a two-dimensional electromagnetic finite element model is built and the current during run-up is tested to serve as the input of the model for force calculation. The force is transferred to structural model and the mode superposition method is used to predict vibration. Then, based on the structural mode information and acoustic transfer vector, noise transfer function between electromagnetic force and sound pressure is established. A balanced efficiency and accuracy of noise calculation during run-up is achieved with this function. Finally, psychoacoustical indices are calculated to evaluate the sound quality with the influence of current harmonics into consideration. The calculated vibration and noise are experimentally validated and the errors of noise level in the whole speed range are all below 4 dB. It is also concluded that current harmonics greatly deteriorate the sound quality.

The permanent magnet synchronous motors (PMSMs) with space vector pulsewidth modulation (SVPWM) technique will inevitably introduce sideband current harmonic components around the carrier frequency. The armature reaction field caused by the sideband current interacts with the permanent magnet field, generating sideband electromagnetic force and resulting in high-frequency noise. This paper provides a comparative study of the sideband electromagnetic force in internal and external rotor PMSMs with SVPWM technique. First, the analytical model of the electromagnetic force in internal and external rotor PMSMs is established based on the Maxwell tensor method. The source, spatial order, and frequency of the electromagnetic force is obtained. Then, the spatial and temporal characteristics of the sideband force in internal and external rotor PMSMs with different pole and slot combinations are derived and investigated. The results show that the frequency characteristics of the zeroth order sideband force in internal and external rotor PMSMs introduced by SVPWM are identical. However, the frequency characteristics demonstrate significant differences for the nonzeroth order sideband force. Finally, the theoretical analysis is validated through the finite element and experimental results, respectively. This study is benefit for the source identification and reduction of high-frequency acoustic noise for PMSMs.

This paper presents an analytical model of the electromagnetic vibration and noise for an external-rotor axial-flux in-wheel motor (AFWM). First, the air-gap flux density is calculated and the influence of edging effect is taken into account through a radial correction function. On this basis, the electromagnetic force acting on the surface of the magnets is obtained. Then, the modal parameters and shapes are calculated and the surface displacement of the AFWM is obtained via a modal superposition method. Finally, sound radiation efficiency is explored to predict the electromagnetic noise. The analytical model is validated through simulation and experiment, respectively. It turns out that the analytical model can predict the electromagnetic vibration and noise of the AFWM quickly and effectively over a wide speed range, which is of great significance for the design of low-noise axial-flux motors.