The most common method to suppress electromagnetic vibration is to weaken the electromagnetic force harmonics, which are the vibration sources. Clearly, vibration is related to some other factors, too. Therefore, in this article, a modal analytical model and the transmission function of a permanent magnet synchronous motor are studied, based on which a fast analytical method of predicting the electromagnetic vibration is proposed, so that the vibration can be preliminarily evaluated during the machine electromagnetic design. The time-consuming 3-D finite-element method is not needed when predicting the vibration. Moreover, using the fast prediction method, a 15-D multiobjective optimization problem for vibration, torque, and efficiency performances is solved in stages. After optimization, the vibration is greatly reduced, and the torque performance is improved. The proposed methods are also proved to be applicable for different operating conditions and types of motors with various slot–pole combinations.

In high-speed surface-mounted permanent magnet (SPM) brushless machines, time- and space-harmonic excitations can induce significant eddy currents flowing in the rotor conductive parts. An effective measure to suppress the eddy currents is to employ a copper shield between the magnets and the retaining sleeve. In this article, a Fourier-based analytical model is proposed to evaluate the rotor eddy current losses. The model is set up in the cylindrical coordinate system and is able to compute the eddy current fields and losses in all rotor domains, that is, the sleeve, shield, magnets, and shaft. Although it is generally believed that both ordinary Bessel functions (OBFs) and modified Bessel functions (MBFs) are workable for solving the magnetic vector potential, it is argued in this article that only the MBF-based models are numerically stable when the high-conductivity domain (e.g., the copper shield) exists, while the OBF-based models may result in irrational results. Both the OBF- and MBF-based analytical models for a prototype motor are established and comparatively studied, with verification of the finite-element (FE) method. Moreover, the cause of losing analysis accuracy in the OBF-based models is revealed.

Post-assembly magnetization can significantly simplify the manufacturing of the rotor of permanent magnet (PM) electrical machines. The optimization of the post-assembly magnetizing device using finite element analysis (FEA) is time-consuming; therefore, a globally optimal solution aiming at achieving an adequate magnetizing level and minimal energy consumption is difficult to achieve. In this paper, a field–circuit coupling analysis (FCCA) model is proposed to optimize the auxiliary stator-type magnetizing device for interior permanent magnet synchronous machines (IPMSMs). A reasonable simplification of the highly saturated magnetic circuit is made based on FEA results so that the magnetic equivalent circuit (MEC) model can be established. On the other hand, the eddy currents in the PMs are equivalent to an eddy current short-circuit; thus, by converting the field calculation into a circuit calculation, the time cost can be reduced significantly, which greatly improves the speed of multi-objective optimization of the magnetizing device with multiple degrees of freedom. A V-type IPMSM is taken as a study case, and its post-assembly magnetizing device is optimized with the proposed method. FEA and experimental results show that the PMs are fully magnetized, while the required energy consumption is greatly reduced when compared with an existing magnetizing device.

In recent years, there is a growing demand for permanent magnet synchronous motors (PMSMs) with reduced electromagnetic (EM) vibration, so as to achieve better NVH performance. EM vibration is induced by a set of spatial and temporal EM force harmonics, and can be evaluated through a 2-step finite element (FE) simulation. However, with a large scale of input parameters, it is impractical to optimize the EM vibration based on direct FE simulation due to the time consumption. In this paper, a response surface is generated based on the historical FE simulation data, replacing the FE simulation procedure. Based on the response surface, the EM vibration amplitude is optimized using the Particle Swarm Optimization algorithm. Since the optimization process no longer requires FE simulation, the optimization speed is greatly accelerated, and the optimal results can be obtained in a few seconds. As a result, the EM vibration of the motor is significantly reduced, while other performances (e.g. torque and efficiency) remain unchanged.