Research Of DC Charger Water Cooling On Relevant Parameters

Electrical vehicle(EV)is the predominating direction of the future car market with the advantages of low environmental pollution,low noise,energy saving and so on.Charger is the essential configuration which provides energy for EV.Necessary cooling measures usually need to be taken;the radiator will produce parasitic effects and cause electromagnetic interference(EMI).EV charger water cooling is taken as an example in the thesis.Three measures are taken to restrain the parasitic effects,the effects of these measures on the heat dissipation capability of the radiator are comprehensively considered,which provides important reference significance for optimizing the performance of heat sink.The losses of the charger power module are firstly analyzed.The frequency of the charger is relatively high,output power relatively large as well as power loss.The power loss converted into heat,resulting in a rise in the internal temperature of the charger system.Temperature rising too much not only has a bad impact on the system performance,but also curtails its life span.The losses of IGBT module are calculated,which are the main source of heat,and the effects of temperature on the loss are corrected,to lay the foundation of temperature simulation in the later chapter fourth and fifth.According to the path of heat transfer,the heat equivalent circuit diagram is obtained and formula for junction temperature caused by power loss is deduced.Secondly,the parasitic capacitance caused by radiator is introduced,the damage caused by parasitic effects is described,the common-mode current flowing throw the parasitic capacitance is obtained.Inserting the copper shielding layer in the thermal grease,changing the radiator structure and increasing the thickness of thermal grease are the three measures taken to suppress parasitic effects.Parasitic capacitance is calculated by the use of ANSYS Maxwell,the parasitic impedance frequency characteristic of parasitic capacitance is obtained.Thirdly,considering the effects of these measures on the capability of the radiator,the simplified water cooling heat sink model is built in ANSYS Icepak.The temperature distribution nephogram is obtained by steps of model building,meshing,solving and post-processing.The effects of different environmental temperature,different inlet water flow rates,different coolant mediums and different inlet water temperature on the radiator heat transfer performance are simulated.Finally,three kinds of measures to restrain the parasitic effects carried on temperature simulation.The simulation results show that the insertion of the copper shielding layer and the change of radiator structure not only play an important role in suppressing the parasitic effects,but also enhance the heat dissipation capacity.Although increasing thickness of thermal grease has a certain positive role in suppressing parasitic effects,with the thickness of thermal grease increasing,heat dissipation capacity decreasing more quickly.When this measure is taken to suppress the parasitic effects,the effects of this measure need to be considered in actual engineering application.The research results can provide certain guiding significance for the optimization design of the heat sink in the suppression of parasitic effects and optimization of cooling capacity.