Calculation and Experiment of Electromagnetic Force of the Axial AMB used in HTR-PM Main Helium Blower Prototype and its Dual Material Selection Method

The Active Magnetic Bearing (AMB) is used in the main helium blower in the High Temperature Reactor-Pebble-bed Modules (HTR-PM) which is being constructed in Shandong province, China. The axial AMB is very large and works under extreme conditions. The calculation deviation of the electromagnetic force of the axial AMB was studied experimentally. Through measuring B-H curve of the material in large range of magnetic field intensity, considering flux leakage in calculation, and considering residual magnetism and the change of the gas gap in measurement, the calculation deviation reduces to 10%, with most values less than 5%. The material selection method of the axial AMB working under extreme conditions was studied experimentally. Through measuring the electromagnetic force when the stator and the thrust disc are made of different materials, it’s found that the force mostly depends on the stator. Combined with the analysis of the stress distribution of the stator and the thrust disc under working condition, the dual material selection method is proposed. That is, the stator material should have good magnetic properties and its mechanical properties are not very important, however, the thrust disc material should have good mechanical properties, and its magnetic properties are not very important.