Thermal Analysis And Cooling Structure Optimization Of Permanent Magnet Motor

In order to solve the problem of high temperature rise of permanent magnet motor, the temperature field should be calculated and the overheated spot should be found in time when the motor is designed. The cooling structure can be used to adjust the temperature of the permanent magnet motor. Digital design of permanent magnet motor is realized in this way. The paper studies the temperature field of the permanent magnet motor and does the work of the temperature calculation and the cooling structure optimization.First, with the traditional formula in the theory of heat transfer and electronics and the method of finite element(FEM)simulation, the loss of the permanent magnet motor is calculated. The loss is classified, including core loss, copper loss and the mechanical loss. The thermal conductivity and coefficient of heat transfer is determined. The experience formula for computing the mechanical loss is found. In the calculation of copper loss, the effects of temperature on the resistance value is fully considered.Secondly, with the method of the equivalent thermal network and FEM, the temperature is calculated. The equivalent thermal network model of the permanent magnet motor and the heat equation is established. Then the temperature equation is solved in large sparse matrix model. And FEM is adopted to the temperature of the permanent magnet motor for steady state and transient analysis of permanent magnet motor. The temperature field of the permanent magnet motor is calculated, and the data is compared with data of the experiment. The overheated spot is found out. Therefore, the real-time monitoring of the motor can be achieved. The deviation can be within 7%.The cooling methods and the cooling neurogen is analised and compared. Then the water is choosed as cooling medium. The impact of the cooling systerm is added to the whole model to calculate the temperature field. The temperature field of axial 2 water channel and axial 8 water channel is analised. And the analysis of the effect of the different flow velocity on the temperature rise is carried out to find the best solution in order to achieve cooling structure optimization.At last, the permanent magnet linear motor is selected as the prototype and a platform of the permanent magnet linear motor is built. The motor temperature rise is recorded to verify the calculation precision of the calculation model. Through the above analysis, the calculation of the temperature field of permanent magnet motor gets more accurate, and the problem can be found in time which is conducive to the development of the degital design of permanent magnet motor.