The Airgap Magnetic Field Analysis And Performance Study Of PMSM With Nonuniform Halbach Magnet

The way of increase PMSM’s power density or deduce torque ripple had always been the research hotspot. The Halbach magnet array has potential features like high flux density,providing sinusoidal field distribution and self-shielding,since which more and more attraction has paid to it in many electromagnetic engineering domains such as electrical machines.Halbach permanent magnet array had been researched a lot by domestic and foreign researchers, most of the researches are focus on the segmented Halbach permanent magnet array.For now the better choice is segmented Halbach magnet array consider the manufacturing and processing technology of permanent magnet, and the number of the segment shouldn’t be too much.The contribute to the magnetic field of different segment of the Halbach permanent magnet array is obvious different when the number of the segment is not much. So the research of contribution of the segment of the Halbach permanent magnet array is important, currently the research of nonuniform Halbach permanent magnet array hadn’t been seen at home and abroad.First this paper originated the concept of nonuniform Halbach permanent magnet machine, further originated the concept of proportion of the main pole. An PMSM model with nonuniform halbach magnet which per pole has 3 segments which ignore the stator slot is presented,the number of poles and the proportion of main pole are analytical parameters, the analytical solution of distribution of airgap radical magnet field of PMSM is deduction, then verified through FEA. This paper research the influence of proportion of main pole to the distortion rate and fundamental amplitude of airgap magnet field of nonuniform Halbach permanent magnet machine, and contrast it with the normal Halbach machine and surface-mounted PMSM, the priority of the nonuniform Halbach PMSM is verified.Analytical solution of distribution of airgap radical magnet field of nonuniform Halbach PMSM which consider the slot of stator is deduction by the method of conformal transformation in this paper in order to research the performance of the nonuniform Halbach PMSM,then verified through FEA. The analytical solution of cogging torque of nonuniform PMSM is deduction by the Maxwell stress tensor method, then this paper research the influence of the proportion of main pole to the cogging torque of nonuniform Halbach PMSM, the result found out that the nonuniform can improve the cogging torque of the Halbach PMSM. This paper’s research found the theoretical basis of the optimal design of the nonuniform Halbach PMSM.