Calculation Of Eddy Current Losses And Analysis Of Performance For Double Cans Composite Rotor Motor

The stator and rotor cans of double cans composite rotor motor could prevent the motor from the erosion of transmitted mediums. Ferromagnetic solid rotor embedded with rotor bars is adopted. All of those make this special kind of motor has the same operating characteristics as the ordinary canned motor and the composite rotor motor. Therefore, it is widely applied in national defence, petrochemical industry and other fields. However, because of special construction, the distributions of eddy current and magnetic field are complex, and there are still some problems in calculating and analyzing the influences on performances of double cans composite rotor motor.According to double cans composite rotor motor's structure characteristics and engineering design requirement, the eddy current losses of every structure and performances of motor were deeply studied by computing magnetic field in this paper.Firstly, mathematic model of double cans composite rotor motor about 3D nonlinear eddy current field was presented, and the method to calculate eddy current losses and the stator end windings reactance by the result of eddy current field computation was brought forward.Secondly, using 3D FEM the eddy current losses of motor's end region were computed, and then the stator end windings resistance and reactance were derived. Based on these, the motor's model without end region was calculated at no load, starting and rated load. The eddy current of the stator can, rotor can and the composite rotor under different conditions were acquired, as well as the motor performances such as torque, efficiency, and so on. The influence of skewed rotor on the electromagnetic performances was quantitatively analyzed by comparing with the results without skew. Thirdly, eddy current losses of cans were calculated by analytical formula and empirical equation. The eddy losses of cans with different thickness, resistivity and permeability were computed and analyzed separately. The influences of these parameters on cans'eddy current losses and motor's performances were gained.Finally, using 2D transient FEM to calculate a double cans composite rotor motor, the motor's dynamic performance curves (such as current, electromagnetic torque, load torque and speed) under no-load starting and full-load starting were acquired. At the same time, the distributions of magnetic flux density at different time were gained.All these can benefit the theoretical analysis and the optimized design of double cans composite rotor motor.