Radial Position Control By Maglev For Vertical Bearing System Based On DSP

Electromagnetic bearing is a complex system which contains mechanics, electronics and electromagnetics. Those years, researchers are involved in the position control algorithm of dynamic rotor and circuit design of the electrical control system.The thesis is based on the project named " Maglev washing machine of direct drive type", which is funded by Haier research and development center, for the problem of barrel’s oscillation during the rotation. In this thesis, the washing barrel is considered as a vertical magnetic bearing rotor, and the control principle and electronic drive system are same as the magnetic bearing system. This thesis is focused on the electronic drive control system of vertical magnetic bearing, the following work are mainly studied in the thesis:Firstly, the basic composition and the principle of magnetic bearing are briefly introduced, and then the dynamic analysis and control algorithm in of rotor in stationary state are simulated by software MATLAB.Secondly, the thesis is focused on the power amplifier, which is important in the system of electromagnetic bearing. Because the linear power amplifier has low efficiency and energy loss, so the topologies, ripple and modulation of the switching power amplifier are analyzed. Then I use Saber to simulate circuit, the results are consistent with the theoretical analysis. The hardware design of the switching power amplifier mainly includes:circuit of current sampling, circuit of PWM phase shift, driving circuit of MOSFET, isolating circuit and improved half- bridge circuit, etc. The results of experiment show that the three-level modulation can greatly reduce the ripple of output current, and its dynamic characteristics as well as output characteristics meets the design requirements.Thirdly, TMS320F28335 is adopted as the main controller, we design the hardware of the controller, including DSP minimum system, ADC and DAC, displacement signal processing circuit, RS232 communications interface circuit, power management circuit, peripheral interface circuit, etc. On the basis of the hardware circuit, using CCS3.3 DSP software development platform to complete the signal sampling, PID algorithm and register configuration. The results of experiments show that the rotor shakes on a small scale, achieving the radial suspension of the vertical rotor in stationary state.