Optimal Design and Analysis on Bearingless Permanent Magnet-type Synchronous Motors Using Finite Element Method

There are complicated relationships among the radial suspension forces, configuration of windings, permanent magnet thickness and currents in bearingless permanent magnet-type synchronous motors (BPMSM), so researching these relationships has important reference value for designing and optimizing BPMSM. Based on the principle of producing radial suspension forces in BPMSM, the mathematics models of radial forces are deduced. The gap magnetic circuits of BPMSM are studied using finite element method when the currents in radial force windings are changed. The demagnetization of permanent magnets is considered. The most critical area in the permanent magnets is made clear for both torque and radial force generations. The relationship between the radial suspension forces and permanent magnet thickness is calculated and analyzed when the permanent magnet thickness is changed under the fixed motor gap. The radial suspension force and the Maxwell force of the additional 2-pole radial windings and additional 6-pole radial windings are compared under the 4-pole motor windings. The relationship between radial suspension force and current is tested on prototype machine with p_M=2 and p_B=3 under the state of static suspension; the experiment conclusions have proved that the account results are accurate by using ANSYS software