Optimization Design Of Configuration And Drive Control For Ac-dc Magnetic Bearings

A magnetic bearing is the novel high performance, non-contact bearing, and its rotor is suspended in space by magnetic forces. The magnetic bearing has the advantages of no abrasion, no need of lubrication and seal, high speed, and long life, which has innovated the traditional supporting forms fundamentally. In the dissertation, a novel AC-DC 3 degrees of freedom hybrid magnetic bearing (HMB) is proposed, which is driven by DC in axial direction and by a three-phase power converter in 2 radial directions respectively, and the permanent magnet provides the axial and radial biased magnetic flux, the structure of the stator and rotor with cone-shaped faces realizes control in 3 degrees of freedom using the same air gap.In the dissertation, based on the support of National Natural Science Foundation of China, optimal design and basic theory of AC-DC 3 degrees of freedom HMB are studied, the power driving system and digital control system of AC 2 degrees of freedom HMB is researched. The detail contents are as follows:Firstly, the structures and magnetic circuits of two AC-DC 3 degrees of freedom HMB are analyzed. Basic structure and suspending force principle of AC-DC 3 degrees of freedom HMB with cone-shaped stator and rotor have mainly studied, the mathematics models of magnetic suspension forces are deduced using equivalent magnetic circuit. The coupling characteristics of movement and magnetic circuit between radial and axial are calculated and analyzed with MATLAB toolbox.Secondly, based on mathematics models and technical specifications given in advance, structure parameters of AC-DC 3 degrees of freedom HMB with cone-shaped stator and rotor are designed. Optimization design of structure parameters, simulation analysis of magnetic circuit and rationality of magnetic bearing's structure are studied using finite element analysis software ANSOFT.Finally, power driving circuits of AC 2 degrees of freedom HMB is designed. Hardware structure and design process of power driving circuits are given in detail. Hardware structure and the implementation of control algorithms of AC 2 degrees of freedom HMB digital control system based on TMS320F2812 DSP are shown. The experimental results are presented.