Influence of magnetic wedge on electromagnetic field distribution of permanent magent traction motor

Abstract

High-speed train permanent magnet traction motor stator slot installation with magnetic wedge, which can improve the air gap magnetic flux density waveform and reduce the harmonic component. However, in the process of high-speed train running, the motor vibration may cause magnetic wedge fall off, which will increase the air gap flux density harmonics. These harmonics will produce more eddy current losses on the rotor surface, thereby affecting the efficiency of the motor. Thus, this paper takes a 315kW permanent magnet synchronous motor as an example. It has established a mathematical model of two-dimensional transient electro-magnetic field prototype stator with non-magnetic wedge. By using time stepping finite element method for solving 2D electromagnetic field equation, the calculation results of the starting current and starting torque are compared with the experiment results to verify the accuracy of the calculation method. The paper investigates the impact on the motor performance by employing different relative permeability magnetic wedge during starting and normal operation. At the same time, this paper also discusses magnetic wedge falling off number and dropping position on the influence of air gap flux density harmonics, eddy current loss on rotor surface and motor efficiency.