Design And Implementation Of Low Loss Magnetic Bearing For Generator

Homopolar and heteropolar radial active magnetic bearings are designed separately for verticalaxis wind power generator rotor system. The equivalent stiffness and equivalent damping of thehomopolar active magnetic bearing are analyzed, and the modal frequency and modal shape of thesystem are calculated. By using the finite element software Ansoft Maxwell, the two-dimensionalmagnetic field distributions of the two kinds of active magnetic bearings, the effects of bias current,rotational speed and the rotor vibration on magnetic flux density of the surface of the rotor, and thepower loss of the two kinds of active magnetic bearings are analyzed in detail. The control programbased on TMS320F28335DSP and incomplete differential PID is developed. The tests of staticsuspension, braking and operation of the system are completed.The results show that, the magnetic lines of active magnetic bearing are symmetricallydistributed uniformly as the rotor is suspended, and magnetic flux density increases with the coilcurrent. The eddy current field produced by the rotation of the rotor has greater influence on themagnetic flux density and the distribution of the magnetic lines of heteropolar active magnetic bearing.The magnetic flux density and the distribution of the magnetic lines change with the amplitude ofvibration of the rotor and the coil current. Homopolar active magnetic bearing has less power lossthan heteropolar active magnetic bearing. Self-programming software can insure safe operation ofthe system. Moreover, the axial active magnetic bearing can implement the brake function of thesystem.