Electromagnetic,Fluid,and Thermal Fields Of Fully Air Cooling High Voltage PMSM

Due to the large starting torque,small starting current and high rotor mechanical strength, the solid rotor permanent magnet motor gets a certain application industrial field. The harmonic magnetic field in the air gap will cause larger eddy current loss on the rotor and lead to temperature rise. Moreover the permanent magnet locates at the rotor core. Temperature rise of the rotor will influence the electromagnetic properties of permanent magnets and even results in the permanent magnet partial or whole demagnetization. So it is important to study the rotor temperature distribution and the optimization of the ventilation structure.This thesis takes a315kW,6kV solid rotor permanent magnet motor as an example. Firstly, based on the theory of electromagnetic field, the2D electromagnetic step finite element model of the prototype was establishment. The loss is calculated for each part of the motor, and the three-dimensional fluid-solid coupling model has been established according to the properties of the ventilation structure. Temperature distribution of the rotor core and the permanent magnets was mainly studied.Secondly, to reduce the temperature rise of the rotor, the magnetic wedge has been sited at the stator slot. The wedge relative permeability influence on the eddy current loss of the rotor and the starting torque have been calculated. On this basis, by solving the three-dimensional fluid-solid coupling heat-transfering equations, temperature distribution in the parts of the motor stator and rotor were obtained. The maximum temperature of the rotor core and permanent magnets are analysied with magnetic slot wedge having different relative permeability values.Thirdly, to improve the the cooling effect of the rotor, air ducts are sited on the rotor. The influence of air ducts number and location on the motor starting torque starting process and loss have been studied. The air flow state in air gap, stator radial ventilations and rotor air ducts have been analyzed in detail. Revealing the rotor core and permanent magnets temperature distribution along the motor axial and radial direction.Finally, the influence of the rotor radial ventilating duct number and position on the wind velocity in the rotor axial and radial ventilation ditches are studied. The flow distribution between the rotor radial ventilations was also studied. At the same time, the temperature distribution of the rotor core and permanent magnets are studied. Maximum temperature of stator parts are calculated with the rotor having different radial ventilations number.The conclusion can be used as the theoretical basis of the similar motor cooling system design.