Wide Gap Magnetic Bearing System for a Magnetically Suspended Clean Pump

A new hybrid magnetic bearing and motor system for magnetically suspended clean pumps with wide air gaps has been developed. The permanent magnet geometry is examined by three dimensional magnetic field analysis with the finite element method. The optimization method to determine the optimal values of the design parameters has been developed based on magnetic equivalent circuit technique, genetic algorithm (GA) and three dimensional magnetic field analysis. The size of the hybrid magnetic bearing C core, the thickness of the permanent magnets, and the turn number of the electromagnets are optimized by the method. The designed HM bearing and motor system has an outer diameter of 100 mm, a length of 140 mm, and air gaps of 3.5 mm. The optimized system produces a target attractive force of 20 N with an excitation current of 0.5 A and the ratio of force to excitation current is 40 N/A. The devised hybrid magnetic bearing indicates sufficient bearing performance for the target clean pump and the developed optimization method displayed sufficient ability to design the hybrid magnetic bearing.