Thermal Performance Analysis Of Megawatt High-speed Permanent Magnet Motors

With the accelerating process of social industrialization,the single machine capacity of generator increases.Compared with the traditional medium and low speed generator,megawatt high speed permanent magnet generator has the characteristics of small volume,light weight and small moment of inertia.But at the same time,the high material utilization also leads to the increase of generator loss per unit volume and the decrease of generator heat dissipation area,and the high temperature rise has become the main factor limiting its development.Therefore,it is of great significance to study the internal heat dissipation performance and temperature rise distribution of megawatt high-speed permanent magnet generator.In recent years,the finite element method has become the main method to study the temperature field of the generator.However,due to a long time of modeling and dissection in the early stage,it is not suitable for the rapid parametric analysis of the thermal performance of the generator.In this paper,for a 1MW high-speed permanent magnet generator,the lumped parameter thermal network method is used to realize the rapid parameter design of the generator,which can ensure the calculation speed and accurately grasp the generator temperature rise.Firstly,the solution domain of 1MW high-speed permanent magnet generator is divided and discretized,and the thermal network model is built according to the structural characteristics of the generator.The target generator adopts axial and radial ventilation cooling mode,and the cooling path is complex.In order to set accurate heat dissipation boundary,computational fluid dynamics method is used to solve the air flow state in each fluid domain of the generator,the fluid structure coupling calculation of generator temperature rise is realized.Compared with the experimental data,the accuracy of lumped parameter thermal network method is verified.Secondly,in order to compare the cooling performance and temperature rise distribution of the generator under different cooling conditions,the computer-aided software is used to multi segment process the main temperature rise structural.It overcomes the disadvantage that lumped parameter thermal network method can only solve the average temperature rise of each structure.Combined with the fluid flow characteristics of the generator,the temperature rise is calculated,the fluid flow characteristics of the generator and the radial temperature distribution of the generator under the conditions of all air cooling and air hydrocooling are analyzed emphatically,and the beneficial conclusions related to the thermal performance of megawatt high speed permanent magnet generator are obtained.Finally,because the lumped parameter thermal network method can be used to design parameters quickly,combined with the thermal network model of the generator,the thermal path parameters under the main heat transfer path are selected for temperature rise sensitivity analysis.Through the full factor experimental design,the influence of different parameters on the generator temperature rise is compared,and the key parameters affecting the temperature rise are obtained,which can provide a theoretical basis for the thermal performance design and optimization of the generator in the future.