Analytical solution of electromagnetic noise caused by radial force and torque variation in fractional slot PM motors with all teeth wound
This paper presents the analytical method for analyzing the electromagnetic noise in fractional slot permanent magnet (PM) motors. The electromagnetic noise is mainly caused by the radial force and the torque variation. On load condition, the radial force density can be evaluated by integrating the open circuit magnetic and the armature reaction field using the conformal mapping and the winding function and as a result, the analysis takes into account the effects of slotting and the winding distribution. The knowledge of the radial and tangential components of open circuit magnetic field allows one to derive closed form solutions for torque variation equal to the sum of cogging and electromagnetic torque. The solutions derived from the analytical method are implemented on a 10 pole/15 slot motor and compared with finite element analysis (FEA) Since the FEA requires excessive computation time without providing closed form solutions, analytical model presented in this paper shows significant advantages with the accuracy of the computation.
2017 IEEE Transportation Electrification Conference and Expo (ITEC)