Research On The Hardwar For Active Magnetic Bearings System Based On DSP

Active Magnetic Bearing (AMB), with advantages of no friction, high speed, high precision, make the rotor be suspended by controlling the magnetic force. It has so many characteristics that it is considered as a technology revolution of the bearings. The AMB is an advanced technology, which relates to many science fields such as mechanics, rotor dynamics, electromagnetics, electronics, control theory, computer science and so on. In many countries such as USA, France, Japan, and Switzerland, AMB has been industrialized. The domestic research on AMB started from the 80th of last century, but AMB has not been industrialized. So it has important significance for the research on the magnetic bearings.Firstly, the AMB's feature, research status and trends of the development at home and abroad are presented in this paper. The framework and composition of the five degree-of-freedom AMB system are analyzed based on the single degree-of-freedom AMB system'theory. In order to achieve the AMB controlling system, the electromagnetic force is lineraized.This thesis takes the chip TMS320LF2407A as the Digital Signal Processing controller, which is easy to achieve high speed and precision. In this paper, it takes centre-controlling as the scheme, and the basic circuit of DSP is designed.On the basis of the analysis and comparison of some sensors, Eddy Current Sensor is selected, and its equivalent circuit, strength and depth of the eddy current, radial distribution of the current, axile intensity of the magnetic inductorium are all analyzed. The processing circuit of sensor's signal is designed. Because of coupling problem of the sensors, differential measurement of sensor is applied.Electrical and mechanical design of the electromagnet is accomplished in the AMB system. Firstly, magnetic materials are studied. Then in order to reduce the magnetic field coupling of the electromagnet's poles, the number and layout of the electromagnet's poles are optimized for processing and producing. According to the requriements of easy control for the system of electromagnetic force, we chose the electromagnet of differential-voltage for the electromagnetic force. The radius of the electromagnet windings in the radial and thrust bearings are chosen, and the number of wire turns is calculated. The switching power amplifier is designed for the feature of requirement in the AMB system, and the basic characteristic is analyzed. The switching power amplifier is optimized based on the achievement of electromagnetic force, and the circuit structure of tristate power amplifier with soft-switching is designed. This circuit owns the advantages of reducing the dissipationpower on the power component and improving the speed of system dynamic response, enhancing the stability of the electromagnetic force in the final state, and the nice result is presented by the simulation. The small-signal model of the power amplifier is also established.