Core Loss Analysis of Three Degree-of-Freedom Hybrid Magnetic Bearing with Novel Rotor Structure

To reduce the core loss of six-pole RAHMB (radial-axial hybrid magnetic bearing) at high rotation speeds, a novel partially laminated rotor is proposed. Firstly, the suspension force model of six-pole RAHMB is built by using equivalent magnetic circuit method. The structure parameters of six-pole RAHMB are designed according to the mathematical model of suspension force. The core loss and suspension force under different depths of lamination part are analyzed to select the optimal depth value. Then, in the finite element analysis, the rotation speed of rotor is set to be 50000 r/min, and the maximum radial and axial control currents are injected to six-pole RAHMB respectively to analyze the core losses of the solid rotor and partially laminated rotor when the magnetic bearing generates maximum suspension force. Finally, the eddy current loss and hysteresis loss of laminated rotors are simulated and calculated under sinusoidal disturbance current. The results show that the partially laminated rotor can reduce the core loss by 69.7% while producing the maximum bearing capacity; although the axial bearing capacity is reduced by 14.7%, it still meets the design requirement; besides, the core loss is reduced by 55.4% under sinusoidal disturbance current.