Harmonic Constitute Analysis And Optimal Design For Permanent Magnet Synchronous Motor

Permanent magnet synchronous motor(PMSM), owing to its advantages of high efficiency and energy saving, is widely used in the domains of energy, vehicles,aerospace, machinery industry, modern agriculture, etc. However, there are many kinds of harmonic components in the internal magnetic field of PMSM. These harmonic components produce torque ripple which decreases the efficiency of the machine and the control accuracy of the system. Therefore, deducing and analyzing the harmonic models of each parameter for the motor are extremely important for the optimum design of PMSM.In this paper, the design method of PMSM and the optimization of cogging torque are studied based on the harmonic models of PMSM with distributed winding. The main results are as follows,Harmonic models are analyzed based on winding function, reciprocal air-gap and no-load air-gap flux density. According to the laws of physics, the harmonic model equations, such as flux linkage, back EMF, MMF, air gap flux density and electromagnetic torque are deduced. Meanwhile, the harmonic spectrum and the harmonic interaction between different quantities are analyzed.The design of PMSM is investigated in this paper, which includes stator structure,permanent magnet pole, magnetic path, winding structure and so on. Combined with the harmonic models of PMSM, the basic parameters of PMSM are calculated, and a designing scheme of PMSM is given.Finite element software Maxwell was used to simulate for analyzing the PMSM.The simulation and calculation results of the harmonic models are compared so that the reliability of harmonic model in PMSM designing can be verified.In order to solve the problem of tooth harmonics in PMSM, a far more effective optimization scheme is given in this paper, which is about the angle of step skewing.The formula of cogging torque in PMSM is expressed, and the impacts of no-load air gap flux density and magnet segments on cogging torque are studied. With the help ofMaxwell, the conclusion that the cogging torque of PMSM can be preferably restrained by the step skewing of rotor magnet, the construction of non-uniform flux density and magnet segments is verified.Finally, the prototype of the proposed PMSM was designed and fabricated. The characteristic performance curves of the prototype are presented, and the reliability of the designing scheme is verified through the experimental tests.