An Analytic Calculation Method on Air Gap Flux in Permanent Magnet Brushless DC Motor with Ironless Rotor

An analytic calculation method about the air gap magnetic field of the high-speed permanent-magnet brushless DC motor with ironless rotor is presented in this paper. Based on equivalent surface currents method and image method, the mathematical model of the motor is presented. Then the analytical procession is deduced. And the calculated results of the method coincides with that of finite element method. It proves the analytic calculation method is exact and reliable.