The Research Of Eddy Current Loss For The Cycloid Permanent Magnetic Gear

The cycloid permanent magnetic(PM) gear is a kind of magnetic coupling transmission device, and it is mainly composed of stator and eccentricity rotor. At present, the research on the cycloid PM gear is mainly aimed at the operation principle, structure design, static torque and dynamic torque, and little research on its loss. Loss is directly related to the efficiency of the cycloid PM gear, bigger of the loss, lower efficiency. Therefore,it is necessary to study the eddy current loss of the cycloid PM gear. In this paper, theory and experiment have been used to study the eddy current loss of the cycloid PM gear.Firstly, The structure and working principle of the cycloidal PM gear is given. The reason of eddy current loss of the cycloidal PM gear is analyzed, and the calculation formula of eddy current loss is deduced. According to the calculation formula, influence factors of the eddy current loss are obtained.Secondly, A time-stepping finite element method (FEM) based on the borderline slippage method is applied to calculate the eddy current loss in the cycloid PM gear. The calculation results show that the eddy current loss of the cycloid PM gear is proportional to the square of the speed and the conductivity of the material but has nothing to do with the torque. With the increasing of the eccentricity, the eddy current losses of the rotor and stator are increasing, and the eddy current loss of the rotor yoke is smallest. With the increasing of permanent magnet number in each pole, the influence effect of the eccentricity becomes more and more small. With the increasing of the yoke thickness, the eddy current losses of the rotor and stator are increasing, and the eddy current loss of the stator yoke increased significantly. With the increasing of permanent magnet number in each pole, the influence effect of the yoke thickness becomes more and more obvious.Finally, the experiments of general array and90°Halbach array on cycloid PM gear is studied respectively. The experimental results show that the eddy current loss increases with the increasing of speed but has nothing to do with the torque, experimental results agree with theoretical results, The efficiency of the cycloid PM gear decreases with the increasing of speed, increases with the increasing of load torque, and it’s fit for working in the occasion of low speed and high torque.