| At present,the magnetic bearings and magnetic levitation train is a research hot spot at home and abroad,and the most widely used one is the magnetic bearing. Magnetic bearing is a kind of unique and high-performance bearing which uses magnetic force to make the magnetic rotor suspended in the air,and then driven by the rotating motor to make it rotate around a particular axis,result of no mechanical contact between the rotor and the stator.In the five-freedom degree magnetic bearing control system,power amplifier is a very important part.Linear power amplifiers are used in the early stages.Linear power amplifiers,the low efficiency of linear power amplifiers results of the switching power amplifiers with high efficiency,good dynamic characteristics is now used in most of the magnetic bearing systems.As the design of the magnetic levitation power amplifier related to the design theory,electromagnetics,electronics,power-eleetronics,and electromagnetic interferen -ces in the working conditions at the scene are very complex,which result of many problems in the power amplifiers,such as the large ripple of the output current,the unideal following characteristics and repeatability is not good enough and so on.To solve these problems,a PWM-based switching power amplifier is designed in the paper.The integrated chip SG3524 is used to generate PWM wave,and the circuit-protection chip EXB841 is used in the design of the power amplifier.The design of the circuit is simple,stable and reliable.Through performance testing and experiments' analysis,its ripple,step response,input and output characteristics and the linearity of the power amplifier when the electromagnetic coils are in a state of magnetic field coupling are all reserehed and improved in the paper.In order to facilitate the study,the structure model of the discoid magnetic bearing is concluded in accordance with the support characteristics of magnetic bearing rotor and the mathematical model of discoid magnetic bearing system firstly is analyzed.The past,the main circuit structure of the protection circuit is more complex.In the practical application of magnetic floting tecnology,the main circuit is easier affected by outside interferences and caused it lack of stability,so a simple and easy achieved protection circuit based on EXB841 is designed in this article.In this paper,electromagnetic compatibility of magnetic power amplifiers is analized, specific proposals is given.This paper carried out its analysis of electromagnetic compatibility.As power amplifier involves electromagnetics,control theory and computer science and many other fields,many magnetic amplifiers' output current ripple and the following characteristics is worse than ideal situation,those are researched and analised in the paper.Finally,the performance of the power amplifier is tested,and analyse whether the power amplifier can maintain a good degree of alignent when the disc is floting and the electromagnetic coils are in a state of magnetic field coupling.The test of the system in the rioting state shows the power amplifier designed in the paper satisfies the discoid magnetic bearing system,and also with good repeatabi -lity. |
PDF Full Text Request