Research On Control System Of Active Magnetic Bearings Based On DSP

Active magnetic bearings (AMB) are novel supporting components and rotor suspended in the middle of stator by electro-magnetic force. Comparing with the traditional bearing, AMBs have many advantages of non-friction, no lubricated, non-abrasion, high speed operation and so on. The control system (sensors, controller and power amplifier) is a key component of magnetic bearings, has a direct impact on the performance of magnetic bearings. This thesis focuses on the control system of the AMB.In this paper, the AMB development status, characteristics and trends is introduced, the structure and relation of 5 freedom degree AMBs are described in details. By the principle of the electromagnetic theory, deduced the mathematic model of single freedom degree. According to the characteristics of magnetic bearings, the special requirements of position measurement of the rotor, several commonly used sensors are introduced and compared. According to specific requirements of control system, proposed all the hardware design of controller. TMS320C6713A used as controller is a good hardware platform for algorithm, with the peripheral of signal conditioning, A/D, D/A, UART and so on. Analyzed the current response speed requirements of magnetic bearings, discussed the ripple and efficiency of the power amplifier, compared several commonly used power amplifier of magnetic bearing control systems and designed a high-efficiency PWM Switching Power Amplifier.At present, the usual ideal is to get the linearization model at the balance point of the AMB, then to design the linear controller. The design of the controller is able to get good control effects in the vicinity of the balance. But if there has larger disturbance or some system parameters change, it may be shocks for along time, integrator saturation or excessive overshoot. Combine several improved PID algorithms, using variable parameters PID algorithms and establish the rules of the parameters, according to the bearing running condition choose right PID parameters.Finally, test every parts designed, build all the control system of magnetic bearings and debugging the system. Practice show that, variable parameter PID controller meet the requirements of control system, the control accuracy, stability, repeatability is good, it is able to control the magnetic bearings effectively.