In this study, an analytical model is established to efficiently compute the magnetic field and unbalanced magnetic pull (UMP) in axial-flux permanent-magnet motors (AFPMMs). The effects of stator slotting, end effect, and rotor eccentricity on the magnetic field and forces were investigated. Static and dynamic eccentricities are analyzed and considered in the model. An effective function of the air gap permeance was introduced for effect of the stator slots to compute the flux density. A specific coefficient function is defined to calculate the end effect. A Fourier transform is used to compute the variations of the permanent-magnet remanence and the air gap permeance due to the slotted stator opposite to a slotless stator. The unbalanced magnetic forces were evaluated as a function of the air gap magnetic field using analytical equations. The proposed analytical method dramatically reduces the model size and computational time. It can be applied to the analysis of AFPMMs and is much faster than the three-dimensional finite element method (FEM). By comparing with the obtained using the FEM, the model results are validated.

Axial-flux permanent magnet motor (AFPMM) have small size and high power density. It has a good application prospect in the field of new energy vehicle driving. In this paper, based on a 56 kW AFPMM, the magnetic circuit characteristics are calculated by the split loop method, considering the influence of pulse width modulated (PWM) power supply. The loss is taken as the heat source, combined with the motor structure characteristics and cooling conditions, the lumped-parameter thermal network model of the motor is established to solve the steady-state and transient temperature distribution of each structure. By this way, fast and accurate thermal calculation of the motor is realized in design stage. The accuracy of the lumped-parameter thermal network model is verified by experiment. At the same time, the effects of spliting the permanent magnet (PM) into pieces, flow rate of cooling water, and loss distribution on temperature rise are analyzed. This research work provides an effective fast thermal calculation method for AFPMM and provides a reference basis for the design of similar motors. It has important value of theoretical significance and engineering practical.