An analytical complementary FEA tool for optimizing of axial-flux permanent-magnet machines

This paper presents an analytical approach to calculate the magnetic field in a slotted axial-flux permanent-magnet machine. The method is modeled on a simple nonlinear magnetic analysis of an equivalent magnetic circuit with a saturation-possible magnetic-reluctance core in a slotted axial-flux permanent-magnet machine. It calculates flux distribution and torque characteristic in various operating conditions. Its accuracy and validity are verified by results that match those of a Finite Element Analysis model. This method serves as a complementary design tool to FEA especially in expediting design optimization of an electrical machine. The method is as accurate as FEA but betters FEA with its shorter computation time, making it the better alternative in initial estimations. After verification of the analysis, sensitivity to design variables by using the proposed model is presented. The sensitivity analysis through the proposed magnetic circuit of the AFPM machine provides an effective way for selection of design parameters. These parameters are iteratively adjusted through multi-objective optimal design in order to obtain maximum output torque and efficiency. Simulation results show AFPM machine efficiency to be affected the most by its diameter, followed by magnet fraction, and the least by back-iron thickness.