Design And Study On Controller In The Moment Wheel System Suspended By Active Magnetic Bearings

This thesis is based on a project of the Institute of Nuclear and New Energy Technology (INET) in Tsinghua University of China, cooperating with the 812 Institute of China Aerospace Science and Technology Corporation (CASC). The study in the project aims to apply the AMB (active magnetic bearing) supported reaction wheel to the satellites. So it's the application of AMB in the aerospace science. Because it supports a rotor without mechanical contact by magnetic force, AMB has the virtue of little abrasion, low power loss, low noise, long lifetime, no lubrication and controllability of vibration. Therefore, AMB has a brilliant future in the aerospace science and many other domains.Although the related researchers designed a controller and suspended the flywheel successfully with the controller in the former work of this project there existed many disadvantages. Some improvements and innovations are brought forward in this thesis. Firstly, a new controller based on the new generation of DSP (TMS320C6713b of TI Incorporated) is developed successfully. In this process much work including analysis of needs, selecting of chips, design of hardware and debugging of PCB has been finished. The low speed and sampling rate of the old controller restrict the improvement of the system's performance seriously. The new controller not only improves the speed and precision but also increases the modules of measuring the flywheel's speed and communicating with PC, and expands more interfaces of AD/DA (8 ways for AD and 16 ways for DA). All these make the hardware work well which not only establishes the basis of the subsequent research in this project but also can be used in other AMB systems. So it's very helpful for the related research. Secondly, compared with the flywheel controlled by the old controller which is made of aluminum, the one controlled by the new controller is made of steel which makes it more difficult for control. Furthermore the old controller can only control the radial four-axis AMBs and its highest sampling rate is only 10k times per second. Otherwise the new controller can realize the five-axis suspending of the flywheel and work at the sampling rate of more than 150k times per second. It can reach certain targets of performance. There is also much other work done in the thesis. Firstly, the PID method, the cross feedback method and the digital filter are studied and simulated. The software including all these methods has also been developed and utilized which is very helpful for the coming related research. Secondly, the models of all parts in the system have been studied. The power amplifier and the sensor of the displacement have been debugged. And all parts inside of the system have been connected. All these are very important for the realization of the system's functions.Experiments results show that the flywheel can be suspended steadily and the system can reach certain targets. It also proves that the new controller has good performances and can work reliably. The successful development of the controller is important for the research about the AMB supported reaction wheels and helpful for the study in the related domains where the AMB are applied.