Decoupling Control Of Bearingless Synchronous Reluctance Motor Based On Inverse System Method

The technologies of bearingless motors are important breakthrough in the field of high-speed electric drive. Because the bearingless motors have the advantages such as no mechanical friction, no wear, no lubrication, long life, high speed, high precision, etc., it has important research and application value in the field of aeronautics and astronautics, life science, food and chemical industry, new energy storage, high speed electric spindle and so on. In addition to having the advantages of general bearingless motors, the bearingless synchronous reluctance motor (BSRM) has no magnet or excitation windings in the rotor, so it has many advantages such as simple structure, reliable operation and low cost. Moreover, because the BSRM can achieve a high saliency ratio, it also has the following outstanding performance such as high torque density, fast dynamic response, low torque ripple, low loss, high power factor, and etc.. The BSRM is more suitable for high-speed and high precision applications. Therefore, there are obvious scientific value and engineering significance to study the bearingless technologies of synchronous reluctance motor.Control system design is the core and key technology of the BSRM. The BSRM is a multi-variable, nonlinear and strongly coupled system. The main problem of the control system is the couplings among the electromagnetic torque and the suspension forces. The decoupling control is the basic requirement for a stable and reliable operation of the BSRM. The dissertation is sponsored by the National Natural Science Foundation of China (60974053), and focus mainly on the mathematics model, decoupling control, digital control system and so on.The research significance, the recent research and development trends of the BSRM are systematically discussed in the dissertation. The working principle of the synchronous reluctance motor and the principle of the generation of suspension forces for a bearingless motor are introduced. The Maxwell tensor method is used to derive the suspension force equations of the BSRM. The voltage equation, flux equation, torque equation and motion equation are analyzed. Based on these theories, the mathematics model of the BSRM is established. The basic concepts of inverse system and the idea of using the inverse system theory to achieve the linearization and decoupling of a system are described in detail. Taking the five degrees of freedom BSRM and two degrees of freedom BSRM as the research objects respectively, the appropriate decoupling control systems based on inverse systems theory are designed. Aiming at performances of step response, rotor suspending, decoupling control, etc., simulations and analysis have been carried out by Matlab software. The simulation results have shown that this kind of control strategy can realize dynamic decoupling control among electromagnetic torque and suspension forces, and the control systems have fine dynamic and static performance.According to the demand of the control system for two degrees of freedom BSRM, a appropriate DSP control board are developed, and a motor power drive board is designed. Together DSP board and power drive board with the motor, they constitute a digital control hardware system of the two degrees of freedom BSRM. The digital control software system is complete some functions such as signal processing of speed and displacements, PWM waves generation, control algorithms, etc..The research on the key technologies of the BSRM has made some staggered results. These results are not mentioned or not researched further by others in bearingless motor area, and have important value both in theory and practical application. The research of the dissertation provides the foundation for further research on the BSRM.