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Research on digital control system for three-degree freedom hybrid magnetic bearing with bilateral magnetic pole faces

In the paper, a three-degree freedom hybrid magnetic bearing (HMB) with bilateral magnetic pole faces is proposed, which is driven by a 2-phase AC power inverter in radial directions and a DC amplifier in axial direction respectively. The axial and radial biased magnetic fluxes are provided by a common radial polarized permanent magnet ring, and the axial and radial control magnetic fluxes are provided by the inner and outer two-layer coils, respectively. The configuration and producing magnetic suspension forces of an innovated three-degree freedom bilateral magnetic pole face hybrid magnetic bearing are introduced. The flux path is calculated by using equivalent magnetic circuit, the mathematics models of the radial and axial magnetic suspension forces are deduced. The displacement stiffness and current stiffness are derived by linearizing the mathematics models. The experiment prototype's parameters of this magnetic bearing are given. Based on TMS320F2812 DSP, the digital control system of the three-degree freedom HMB with bilateral magnetic pole faces is built. The performances of digital control system of three-degree freedom HMB with bilateral magnetic pole faces has been test by experiments. The start suspension experiment, stable suspension experiment and the anti-disturbance experiments have been done respectively. The relative experimental waveforms and experiment results are given. The research results have shown that the control performances of the digital control system of the three-degree freedom HMB with bilateral magnetic pole faces are well.