Design Of The Cooling System Of High Power Inverter For Pure Electric Bus

Inverter is the core component of the electric vehicle e-driving system,and its performance will directly affect the performance of the vehicle.The reliable operation of IGBT is the key factor affecting the performance of the control system,which means that the IGBT operating temperature should be strictly controlled under the junction temperature,so the design of the inverter cooling system is particularly important.This thesis is based on the practical problems in Engineering and takes the pure electric bus inverter as the research object.Based on the theory of heat transfer and hydromechanics,the inverter cooling system is designed in order to improve the temperature rise during operation,performance and service life of the inverter.Taking "heat source-heat propagation-cooling system design-cooling structure evaluation" as the main research clue,these aspects,such as the power loss of the inverter,the thermal resistance model,the various factors that affect the heat dissipation,the steady state temperature field of the inverter and the test bench,were studied respectively.The main heat source of the inverter is high power switching device,the IGBT module.First of all,the paper researched the heat source to calculate the los s of the IGBT under the peak speed and rated power and then analyzed the installation process and established the thermal resistance model.The thermal resistance measurement experiment was designed to measure the thermal r esistance of the module and the cooling system.The theoretical maximum temperature of the chip was calculated by using the thermal resistance model,which provides a reference for the following simulation and experiment.Secondly,according to the calculated power loss,the cooling m ethod and cooling system layout of the e-driving system was determine.With consideration of the factors that affect the heat dissipation,e.g.housing material,coolant medium and flow rate,different channel structure and rib structure,the cooling system wa s designed.Then the orthogonal experiment was used to optimize the parameters of the fin and find a combination that can meet both temperature and pressure drop requirements and easy to manufacture.Finally,the three-dimensional model of the inverter main components were established,and the professional fluid-solid coupling analysis software STAR-CCM + was used to simulate the temperature field and flow field of the inverter by applying boundary conditions and initial conditions according to the actual operating environment.At the same time,the temperature performance of the inverter was tested,and the test result was compared with simulation and calculation result to certify the accuracy of simulation and theoretical calculation.Through the theoretical analysis and experimental verification,the cooling system of the inverter in the pure electric bus was analyzed and designed,which provides a reference for the cooling system design of this type of inverter.