Multi-objective Optimization Design Of A Thrust Magnetic Bearing With Rectangular Wire Winding

In the pursuit of higher efficiency and power density,many industries ask for increasingly higher rotor speed,which makes the traditional mechanical bearings hard to meet the requirements.Out of the advantages like non-contacting,zero friction,low maintenance cost,long service period,non-lubrication and no oil pollution,magnetic bearings have been widely applied to high-speed motors,spacecraft attitude control systems and flywheel storage systems.However,traditional magnetic bearings are made of circular conductors with low filling coefficient of copper and large waste of slot space,which brings large volume and weight,of course high manufacturing cost as well.The magnetic bearing conductor designed in this study is rectangular,and the winding between the rectangular conductors,namely the flat conductors,is of no gap,which increases the copper filling rate,reduces the groove space,and reduces the design size and weight of the magnetic bearing.Based on the research of the thrust magnetic bearing with rectangular wire winding,this study aims to effectively reduce the volume and loss of thrust magnetic bearings.The main research contents include:(1)Based on the principle of the magnetic circuit law,the dynamic magnetic circuit model of thrust magnetic bearing with the possibility of magnetic leakage will be proposed.Then,the analytical model of thrust magnetic bearing loss and electromagnetic force will be derived on the basis of magnetic circuit model.(2)Based on the thermal circuit method,the thermal circuit model of the thrust magnetic bearing with rectangular wire winding was established and thus the thermal analysis model of stator and thrust disk is derived.(3)Based on the analytical model of loss and electromagnetic force,the multi-objective particle swarm optimization algorithm is used to optimize the existing magnetic bearing model structure,so as to minimize the volume and loss of the magnetic bearing on the basis of meeting the constraints.The finite element simulation method is used to verify the correctness of the analytical model and confirm the feasibility of the structural optimization method.The research shows that--(1)the magnetic force model,loss model,heating model and optimization model established in this thesis are quite accurate.(2)With the increase of the current frequency,the magnetic force of the thrust magnetic bearing of the flat conductor coil is decreasing,while the loss and heat supply are increasing.(3)When the control current is 2A with the frequency of 500 Hz,the thrust magnetic bearing loss of the flat conductor coil optimized by this optimization model is significantly reduced,and the stator volume is also reduced by 13.28%.