| The crisis of energy and environment pollution is two major social issues all over the world.The development of clean energy, such as wind energy, solar energy, and water energy, is becoming the focus of every country. The battery is one of the most common energy storage method, however the energy storage of the traditional battery is of small density, short life and easy to be polluted chemically, which is not able to meet the needs of the community gradually.Therefore, the clean and efficient device for energy storage has aroused much attention. The flywheel energy storage system has the characteristics of long life, high energy storage density,no pollution, free of maintenance and so on, which gains a significant application value in the field of electric vehicles, aerospace and so on. In flywheel energy storage system, the drive motor is a key technology in the energy conversion device. The brushless DC motor is with the characteristics of better speed performance, small size, light weight, high efficiency, can be both used as a motor and a generator, is more suitable to be the flywheel energy storage drive motor compared to other types of motor. However, due to the in presence of friction and abrase, there is dust and pollution in the traditional bearing support of the brushless DC motor, which not only affect the length of the motor life, but also limit the speed of the motor, and it impossible to run in high speed and clean environment. Therefore, the bearingless brushless DC motor has been favored by the majority of scholars with the characteristics of no friction, no need for lubrication, high speed and long life. In this dissertation, the key technologies of brushless DC motor are studied in this dissertation, and theories and experiments of the key technology are carried out. The detail contents are as follows:Firstly, based on domestic and foreign literatures, the development status of domestic and foreign research on flywheel energy storage system and bearingless BLDC motors is analyzed and the key technologies and the development trend are discussed.Secondly, the structure of a new type of bearingless brushless DC motor is presented, the principle of torque and levitation force are analyzed detailly in this dissertation, based on which the mathematical model of the torque and the mathematical model of the radial suspension forces are derived. And it lays a theoretical foundation for the design of control system of the BBDC motor.Thirdly, the bearingless BLDC motor control system is designed and a new controlling strategy for the 12 phase suspension windings is proposed. The realization of three kinds of state motor(charge), generator(discharge), and standby of the torque subsystem and the realization of the control system of suspension force subsystem are expounded. The platform of MATLAB/Simulink is used to build the simulation model of the torque subsystem and the simulation model of the suspension force system. And the simulation results are analyzed.Finally, the digital control system for bearingless BLDC motor is designed based on the platform of TMS320F2812. The principle and function of each module is elaborated and the software system is designed. Some experiments are carried out using the prototype, and the experimental results are analyzed. |
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