Optimal Design And Control Research On Bearingless Permanent Magnet Synchronous Motors

A bearingless permanent magnet-type synchronous motor is hybrids of magnetic bearings and permanent magnet electric motor. The radial force windings are wound together with motor windings to produce radial forces. The permanent magnet synchronous motor has the merits of simple structure, high power factor, absence of the excitation winding and high efficiency. With these advantages, the bearingless permanent magnet-type synchronous motor has widely application foreground in high technical field like semiconductor manufacturing industries, biologic engineering, astronautics and so on.This dissertation is devoted to optimal design and control system research of the Bearingless Permanent Magnet-type Synchronous Motor (BPMSM) including seting up mathematics model, simulating the control system of the BPMSM and developing software of digital control.Firstly, the fundamental principle of the bearingless and producing radial suspension forces in BPMSM is expounded, the mathematic models of rotation part and radial suspension forces of BPMSM are deduced. The model of BPMSM is studied by using Finite Element Method and the motor's work theory is testified. 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 relationships between the flux densities and the currents under a limitation of demagnetization are analytically derived. The BPMSM is designed optimally.Secondly, based on the mathematics models and the control strategy, control system is constructed using Matlab/Simulink toolbox. The startup performances of rotor suspension are simulated. Simulation results have shown that rotor can suspension steadily, torque and radial suspension subsystems can operate independently.Finally, the software based on the digital control system using TMS320LF2407A is designed and the flowcharts of corresponding algorithm are presented. Based on the prototype of 2 degrees of freedom Bearingless Permanent Magnet-type Synchronous Motor, the software have been developed and debugged, and the experiment results are gained and analyzed.