Research On DSP-based Embedded Digital System Of Magnetic Levitating Bearing

Active magnetic bearing (AMB), a high-performanced integrative machine-electricity bearing which employs attractive electromagnetic forces to support a rotor without a mechanical contact, has been called a bearing revolution all over the world. AMB is supposed to have vast and promising applicational prospect due to its advantages, such as high rotate speed, low power dissipation, low noise and longevity. However, since AMB research has stepped into many technology fields, such as mechanism, electronism, computer science, cybernetics, sensor, etc., so far no perfect theory and designing method can be provided. Especially, no successful domestic application of AMB has been achieved. Consequently, it is extremely urgent for us to put more attention to the research on AMB system. Amongst all parts of an AMB system, control system is a significant one because it is of great impact on the operation performance of the AMB system. Thus, the designing of control system is deemed as one of the keystones and difficulties during an entire AMB system designing.In this paper, the worldwide AMB development status is analysed and a conclusion of the current problems and difficulties in AMB system designing is given.Next, the integrated framework of AMB system architecture is established. The main functions and technology index of each part of the AMB control system are clearly explained.By applying the electromagnetic theory and relevant mathematic theory, the formula of AMB electromagnetic force and single degree-of-freedom model are deduced.Based on the control mathematic model, this paper proposes the hardware design plan of embedded digital control system, according to which the controller hardware circuit is designed with a core processor, TMS320F2812. The design of current-controlled PWM switch amplifier is explained by firstly listing the technical details. Grounded on the distributed control idea, the traditional PID algorithm is employed in control system and improved according to the characteristics of AMB. Moreover, the adaptive single-nerve-cell PID algorithm is posed to be applied in AMB control system to realize the self-adjustment of the parameters. This paper lists all the flow charts to illustrate the realization of the algorithms. In addition, the valuescaling of the parameters is explained.The figures of the rotor suspending effect traced out according to the experimental data are presented to illustrate the control system performance. The experimental results show that, this DSP-based digital magnetic levitating bearing control system features advantages of high stability, high control precision, strong stiffness, fast response and low noise.