Analysis And Optimization Of Heat Dissipation Of Electric Air Compressor For Fuel Cell

With environmental problems becoming more and more serious,fuel cell power system which named clean energy is one of the key research objects of future automobile power.Air compressor is one of the vital part of the fuel cell air supply system.Electric centrifugal air compressors generally use motor direct drive.Due to the advantages of compact structure,small size,good sealing,light weight,low vibration and high efficiency,it has gradually become the first choice for vehicle fuel cell air compressors.However,because of the high-frequency and the high-speed,Air compressor’s loss is relatively high.Moreover,it is small in size and difficult to dissipate heat,which can easily cause problems such as bearing damage and permanent magnet overheating and demagnetization.Therefore,the research and optimization of the temperature field in the air compressor are very important.In this paper,a series of researches which contain performance,loss and Temperature field are carried out with a 20 kW,70,000 r/min two-stage supercharged centrifugal air compressor as the research object.Firstly,according to the internal temperature field of the air compressor,the eddy current loss caused by electromagnetic and the friction loss caused by friction are calculated.Because of the high current frequency,electromagnetic losses are divided into eddy current loss of each part and core loss of the stator,and cannot be ignored.Friction losses are divided into air friction losses and friction loss at the bearing.Because of the small air gap length between the stator slot and the rotor of the air compressor,friction loss is the main source of total loss.For friction loss,the change rule under different speeds is studied.Secondly,the impellers at both ends of the air compressor are very important.Under different working conditions of the air compressor,pressure,velocity and temperature of the Cooling water in the flow channel are calculated.Through the combination of experiment and simulation,the pressure and temperature are compared to verify the accuracy of the calculated temperature value.Then,combined with the temperature of the impeller back disk and internal loss distribution,the internal temperature model of the air compressor is created.Compared with the experimented temperature,the temperature value of the bearing,permanent magnet and other parts which are not convenient to measure can be obtained.Finally,the temperature distribution of the cooled compressor is studied and optimized.By discussing the influence of different flow rates,temperatures and cooling media on compressor’s temperature distribution of the,a new hollow segmented rotor structure is designed to enhance the cooling effect of the air compressor.By changing the material of the motor protective cover and the size of the air gap,The total loss of the air compressor is reduced and the temperature rise is reduced.