A novel permanent magnet biased heteropolar radial magnetic bearing with low displacement stiffness

A novel structure of permanent magnetic biased radial heteropolar magnetic bearing (RHMB) is proposed for the requirements of the flywheel energy storage system and the satellite momentum wheel about high space utilization. The permanent magnet of circumferential magnetization is placed to the slot to get the compact structure; meanwhile, low displacement stiffness is acquired because of the shorter coincident circuit between electro-magnet and permanent magnet. Firstly, the scalar magnetic potential method is applied in paper to get the distribution of the electro-magnetic and permanent-magnetic gap flux density considering slot effect and rotor eccentricity, and then a precise magnetic circuit model is built. The force-displacement and force-current relationships are derived by the magnetic circuit model, the linear mathematics model built. The 2D finite element analysis results show that the magnetic circuit model can get the distribution of the gap flux density accurately; the linear mathematics model is validated.