Research On Modeling Of Suspension Force And Operation Control For Bearingless Permanent Magnet Synchronous Motor

Bearingless permanent magnet synchronous motors(BPMSMs) combine all advantages of magnetic bearings and permanent magnet synchronous motors(PMSMs). They obtain many excellent characteristics of magnetic bearings: non-contact, no lubrication, long life, etc., as well as inherit some merits of PMSMs: simple structure, small size, high density, high efficiency, and so on. In recent years, the correlative theories of BPMSMs are being continuously improved, which have potential application values in chemical industry, semiconductor industry, life science, flywheel energy storage, electric vehicle, etc.Supported by Jiangsu Province “333 Project”(2014), Jiangsu Province University Achievements in Scientific Research Industrial Production Advancement Project(JHB2012-39) and “Qinglan Project”, this dissertation does depth researches on the radial suspension generation mechanisms, exact mathematical model, nonlinear dynamic decoupling control, etc. The basic contents are as follows:1. The concept of magnetic field equivalent currents is presented in this dissertation to simplify the complexity of control system for the BPMSM. Using this method, the generation mechanisms of torque and suspension forces are analyzed in detailed and the necessary condition for the generation of suspension force in the constant direction is deduced.2. Considering the influences of rotor eccentricity and radial Lorenz force, the mathematical models of controllable suspension forces are built. The distributions of magnetic flux densities in the air gap and suspension characteristics are verified by means of the electromagnetic analysis software ANSYS/Maxwell. Based on the above analysis method, the suspension force control methods are discussed separately under no-load and load conditions. In addition, the control block diagram is constructed to provide theory basis for the controllable suspension operation.3. A compound neural network inverse nonlinear decoupling control method is proposed, which is based on the concepts of neural network inverse and fuzzy PID controller. By this control method, the BPMSM system is decoupled into three independent integral linear subsystems, namely x-direction radial displacement subsystem, y-direction radial displacement subsystem and speed subsystem. Using Matlab/Simulink, the simulating model of nonlinear dynamic decoupling control is established. The simulation results indicate that the proposed control method has good dynamic decoupling characteristics and better robustness.4. According to the operation principle and design requirements, design schemes of the hardware circuits and software flow diagrams for the BPMSM are provided, and the digital control experiment platform is constructed based on the digital signal processor(DSP) TMS320F2812. The debugging of hardware circuits, rotation test, dynamic and static suspension experiments, and interference immunity experiments are preceded. The correctness and feasibility of the control method are verified by the experiment results.