Unbalance Compensation Research And Optimal Design On PMSM

Bearingless motors have widely application foreground in high technical field like energy resource, astronautics and robots, based on some merits, such as no contact, no lubrication, no wear etc. Compared to the motor with magnetic bearings, bearingless motors have some special merits. First, radial force windings are wound together with conventional motor windings into the motor's stator slots. So the spindle doesn't occupancy radial spaces, radial length of the motor can be designed shorter. When the radial length is the same, output power of bearingless motors are bigger than these of motors with magnetic bearings. Second, the structure of the motor is simpler and maintained conveniently. Especially the power consume is reduced. Traditional magnetic bearings need exciting current producing electromagnetic forces to maintain spindle suspension. But radial forces of bearingless motors are produced based on the rotational magnetic field. The power wastage of radial forces of control system is not half. So it has great significance to study the bearingless motors for improving national defense strength and we may offer some technology in the future to use them in biomedicine, robots, astronautics, etc.The dissertation are devoted to analyzing the magnetic field of bearingless PMSM, calculating the motor's radial forces and torque, researching the mass unbalance compensation control system and simulation using MATLAB.Firstly, the mathematics models of bearingless PMSM are reduced based on the introduction of the fundamental principles of the bearingless PMSM and the radial forces. Then stator, rotor, air-gap and permanent magnet of motor are designed. Using ANSYS software, the motor's work theory is testified and the relationships among radial forces, torque, radial force windings current and torque windings current are calculated. The equivalent current formula is validated and the optimal permanent magnet thickness is found. Then compensation control research executes on the spindle with mass unbalance. With the feed-forward method, the adaptive compensation controller is designed and simulated using MATLAB software. Finally, mass unbalance compensation control minimizing the rotor displacement is realized on the digital control system of bearingless PMSM. The simulation results have shown that this method can improve the motor's gyration precision.