Control System Of Bearingless Permanent Magnet Synchronous Motor

A bearingless permanent magnet synchronous motor (PMSM) is an innovational kind of motor combining magnetic bearing technology with PMSM, which has the virtue of high power factor, high efficiency, high power density, easy control and simple structure of PMSM as well as the magnetic bearing’s excellent characteristics of no mechanical friction, needless lubrication and little maintenance. It can operate under high speed or ultra-high-speed, and has potential prospects in mechanical industry, aerospace, chemical engineering, semiconductor processing and so on.This dissertation is supported by National High Technology Research and Development Program of China (863 Program) project "Research on the application of bearingless permanent magnet synchronous motor in the robot-driven system" (2007AA04Z213). The detail research contents are as follows:1. Based on analyzing the situation of magnetic field distrubution and the force acting on the rotor, the rudimental working pricinple of the bearingless PMSM is demonstrated. By analyzing the magnetic flux coupling relations between torque windings and suspension force windings, a method of transforming mechanical coordinates to electrical one is adopted, then the complete mathmatical models of the bearingless PMSM is deduced.2. The bearingless PMSM is a strong-coupled, multivariable, complicated nonlinear system. How to realize the decoupling control between electromagnetic torque and radial suspension force is a pivotal problem for the motors’stable suspension operation. Under the support of traditional vector control theory, the decoupling control method (that is, rotor flux orientation based on SVPWM) is put forward. On this basis, the control system of the bearingless PMSM is constructed. The valid of the proposed method is testified by modeling simulation with the software of Matlab.3. A new bearingless PMSM system with five degrees of freedom is developed including a bearingless PMSM and a hybrid magnetic bearing of AC-DC three degrees of freedom. Using the chip TMS320LF2407A DSP of TI Company as the digital controller, the digital control experimental system of five degrees of the bearingless PMSM is designed. By the virtue of assembler, the related software is designed, and related program flow charts are given. Considering a bearingless PMSM with two degrees of freedom as researching object, the experimental study on the system of five degrees of the bearingless PMSM is partly carried out, and correlative experiment waveforms are given. The correctness of proposed theory research is testified by the experimental results.The results of theory research and experiment have demonstrated that control performance of the designed digital control system is excellent in the dissertation, which lay some foudations for further research on how to realize the rotor’s suspension on five degrees of freedom.