Simulation And Experiment Of Temperature Field For Active Magnetic Bearing

Active magnetic bearing is an important branch of high-speed motorized spindle. Comparing with the conditional motorized spindle, active magnetic bearing can work in the vacuum condition and contains the advantage of high speed, good controllability, no shaft fretting, long life and low loss. Active magnetic bearing is also an integrated application in mechanical and controlling fields which has broad application prospects in high-tech field such as aerospace, energy and transportation, chemical engineering and mechanical. However in the process of the productizing, some problems should be solved such as improving the control accuracy of rotor of magnetic bearings or the heating problem during its working process which restricts the development of magnetic bearings. Main Works in this paper is focused on the heating problem during the working process of magnetic bearings. Active magnetic bearing realized suspension through the electromagnetic force which is generated by the coils current. The heating problem of the radial magnetic bearings and axial magnetic bearings caused by loss and poor cooling conditions leads to the quickly-raised temperature in motorized spindle. The temperature rise not only lead to the thermal expansion of the rotor which change the size of the air gap between the magnetic bearing stator and the rotor, but also lead to the destruction of the winding insulation layer which result in reducing the performance and reliability of the active magnetic bearing. Hence it is important to analyze the temperature field in the active magnetic bearing and propose the method of dissipating heat of the control system. From this consideration, the temperature field of active magnetic bearing is analyzed, following works were made:The temperature field control equation of active magnetic bearing is established under the heat transfer theory. Checking the typical assembly drawing of active magnetic bearing to clarify each components and matching modes. Find the heat source of active magnetic bearing and introduce the calculation method of copper loss, eddy current loss and hysteresis loss.The transient and steady-state temperature field of active magnetic bearing is analyzed by finite element analysis. The heat conduction model of active magnetic bearing is established using ANSYS under a certain initial and boundary conditions. Heat transfer is happening all the time and the performance of different transfer mode induced temperature distribution can be descript in the form of temperature field which obtained by importing the structure, control and thermal material parameters of active magnetic bearing into ANSYS.The temperature field of active magnetic bearing is measured using thermal infrared imager(Fluke-Ti400). Using analog power amplifier, temperature measuring instrument, IPC and active magnetic bearing to build the temperature field measurement experimental platform. Changing experimental conditions such as the number of coil or the current go through to explore effect of different conditions on temperature field of active magnetic bearing. Comparative analysis reveals the simulation results and the experimental data are almost basically consistent within the allowable error which further verify the accuracy of finite element analysis. The simulation and experiment results provide an important basis for structural design or temperature control of active magnetic bearing.