Principle And Experimental Research Of Micro Permanent Magnet Type Bearingless Motor

The Bearingless Motor is electro-magnetic machine that has the functions of the electric motor and an active magnetic bearing. Levitation windings are wound together with conventional motor windings to produce radial forces in usual bearingless motor. The rotor 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.In this thesis, its developing history, studying contents, developing status andtrend are discussed based on reviewing the development and research of bearingless motors. In order to suit for space application, the usual magnetic suspension principles are analyzed and a novel bearingless motor is proposed. And then the principle of this bearingless motor and the formula of torque and levitation force computed by energy theory is presented. In order to control torque and levitation force, the control method is obtained by formula of torque and levitation.Air gap and thickness of permanent magnet are the most important parameter in PM motor. For getting high power density and high efficiency, we discussed air gap and PM's thickness by finite element methods (FEM). According to the ANSYS soft analysis, the proper air gap and PM's thickness is proposed.Finally, an digital control system using DSP(TMS320LF2407A) is designed and realized to function to this bearingless motor. The results from the experiments of a surface-mounted permanent magnet-type prototype machine suggest the good performance of the suspension.