Research On The Bearingless Technology Of The Permanent Magnet Synchronous Motor

Bearingless motors are hybridized by the motors and the magnetic bearings. Levitation windings are wound together with conventional motor windings to produce radial forces. The rotor shaft is successfully supported by electromagnetic forces and rotates as the conventional motors. Therefore, the total machine sizes are compact compared with the motors equipped with the magnetic bearings. High speed and high power can be achieved. The number of inverters, controllers and electric wires can be decreased, which realizes low cost. As the bearingless motor is constructed with contact-free bearings, it works free of wear, frictionless, free of abrasion and without lubrication. With these advantages and other features, the bearingless motor demonstrates the potential applications in space technology, machine tools, high vacuum technology, ultra high-speed drives and so on.The permanent magnet synchronous motor(PMSM), for its simple structure, absence of the excitation winding, high power factor, high power density and high efficiency, is commonly used in the developing applications of the bearingless drive technology. This thesis focuses on the related theory and experiment study of the bearingless permanent magnet synchronous motor.Firstly, to realize the motor control system, the rudimental principles and basic characteristics of the permanent magnet synchronous bearingless motor are investigated. Through the modeling, the control system of the motor is devised and simulated.Secondly, an analogue and digital control system is designed and realized to function to the bearingless motor. The results from the experiments of a surface-mounted permanent magnet-type prototype machine suggest the good performance of the suspension.