Thermal Analysis Of Direct-current Link Capacitors For Electric Vehicles Based On ANSYS

At present,all countries in the world are working hard to develop new energy vehicles,especially,China put it into the Seven strategic emerging industries.In the field of new energy vehicles,hybrid vehicles(HEV)and pure electric vehicles(BEV)are both adopt AC(alternating current)motor drive,the drive is DC-AC(direct current-alternating current)inverter,which speed by frequency inverter,in addition to the power device IGBT(Insulated Gate Bipolar Transistor),DC(direct current)film capacitors is the main element which used to DC filtering.Nowadays,the volume of capacitor accounted for about 30% of the driver,that one of the key reason of the drive power density,reliability and cost of the capacitor.Miniaturization is the main direction of development,but the product volume is smaller,the radiating area is correspondingly reduced,which maybe caused capacitor failure because of the internal temperature is too high.Therefore,it is of great significance to further improve the structure and the life of the capacitor through heat dissipation analysis.The main purpose of this thesis is to improve the cooling efficiency of the capacitor and improve the life of the capacitor in the design phase of the capacitor.The main work and achievements as follows:1.Firstly,elaborated the basic knowledge of thermal analysis,including the theory of heat transfer,fluid mechanics,dynamics,and thermal analysis process,laid the foundation for the next step for solving the three-dimensional steady flow and heat transfer problems;2.Secondly,a three-dimensional model is established with Solid Works,next the heating mechanism of the capacitor is analyzed,the heat generation rate and the heat dissipation coefficient of the capacitor are calculated.Besides,study on how to use the ANSYS simulation software and Solid Works 3D software interface,expounds the heating mechanism and the methods of thermal simulation by ANSYS simulation tool,based on DC_link capacitor of an electric vehicle.3.At last,prototype test results have verified the accuracy of the simulation,that verification the thermal design method of simulation technology is feasible and reliable.In a word,Electric drive DC filter capacitor has a large capacitance,large current,but miniaturization,which was used in poor environment of the car,the capacitor is close to the IGBT work,temperature and heat balance damage is the main reason leading to the failure of capacitors.In the design stage,use the thermal simulation technology to improve the product structure and reduce the work temperature of DC_link capacitors for electric vehicles will become the main trends and effective method.