| Due to the worsening of the earth’s environment and the shortage of energy resources,followed by strict restrictions on emissions regulations of various countries,new energy electric vehicles have attracted more and more attention and gradually entered people’s life and travel.Especially in recent years,the combination of electric vehicles with artificial intelligence,big data,5G technology and other information technologies has made the quality of the vehicle and driving experience have been improved,increasing the acceptability of electric vehicles in people’s minds.Coupled with the strong support of national policies,the performance of new energy electric vehicles has become the key research direction of universities and automobile enterprises.As one of the core components of the drive system of new energy electric vehicles,IGBT module,one of the core components of the motor and control system,has also attracted the attention of various academic and industry circles for its heat dissipation performance.However,the flow resistance of the cooling water jacket is inevitably ignored when conduct the analysis of the reduction of temperature rise of motor winding,IGBT of the controller and the improvement of cooling performance.It results that the increment of energy consumption of the pump and further affects the driving distance of the electric vehicle.Therefore,when the motor winding and IGBT of the controller meet the heat dissipation requirements,how to ensure a satisfactory flow resistance is a problem to be faced in the cooling structure design of motor and its controller.A cooling structure of micro electric vehicle drive system is taken as the research object in this paper.Based on numerical simulation and experimental test,the temperature and flow field analysis is conducted by monitoring of the motor winding temperature,the temperature of the IGBT and the structure of the cooling flow resistance.Finally,the multidisciplinary optimization model is built,aiming at important parameters of cooling structure.An optimal balance between cooling and cooling flow resistance of cooling water jacket is found in the motor winding and controller IGBT.The main research contents are as follows:1.Heat dissipation and flow resistance of the current prototype and controller under the target working condition is tested.2.The simulation model of thermal-structure coupling is set up and the heat dissipation performance of the motor and its controller and the flow resistance characteristics of the cooling water jacket under the target working condition is calculated and analyzed.The accuracy of the numerical calculation model is verified with benchmark test results.Based on the simulation results of flow field and temperature field,the parameter variables and value range of subsequent optimization of cooling structure are determined.3.For several design optimization variables of the cooling structure of the motor and controller,the sensitivity analysis is carried out by orthogonal experimental design,so as to seek out the relevant optimization variables that have a great influence on the flow resistance,winding temperature rise,IGBT body average temperature.Based on ISIGHT platform,the flow resistance of integrated cooling structure and the temperature rise of motor winding are optimized by single-objective intelligent optimization,and the temperature uniformity of IGBT is analyzed based on the sensitivity analysis results of orthogonal experimental design.4.Based on the results of single objective intelligent optimization,a mathematical model of collaborative optimization was designed to build a cooperative optimization strategy framework with high heat dissipation performance and low water resistance.Three kinds of cooperative optimization designs with different weight ratios were solved.The group of the bigger winding temperature rise weight ratio was selected as the final optimization result.The variables and parameters of the optimization results were modeled by CATIA again and verified by numerical simulation.The flow resistance performance of cooling water jacket,heat dissipation performance of various components in the motor and temperature uniformity of controller IGBT before and after optimization were compared and analyzed.The final optimization results show that:1)After optimization,the local vorticity and flow dead zone of cooling water jacket are improved,the flow is smoother,the flow velocity is more uniform,and the flow resistance is significantly reduced.Compared with the original model,the flow resistance is reduced by 12.5 k Pa,or 39.4%.2)After optimization,the temperature of stator,winding,rotor and permanent magnet inside the motor are all decreased,and the maximum temperature of winding end decreases by 3.28 ℃,or 2.7%,compared with the original model.3)The temperature uniformity of IGBT module in the controller is significantly improved.Through a series of numerical simulation and optimization of the micro-electric vehicle drive system cooling structure,the following conclusions are drawn:1.The high temperature in the permanent magnet synchronous motor is mostly located at the end of the motor winding.The IGBT module in the controller is prone to uneven heat dissipation distribution due to the unreasonable design and layout of the cooling structure.2.Among the four parameters of channel number,channel thickness,channel width and channel end chamfer of motor cooling structure,channel thickness and channel width are strongly correlated with flow resistance,while channel number,channel thickness and channel width are strongly correlated with heat dissipation performance.When designing the cooling structure parameters of the motor,besides considering the manufacturing process and layout,the correlation conclusion can provide some reference for its design.3.The final results of multi-objective cooperative optimization show that the proposed optimization method can be applied to this kind of multi-objective balanced optimization problem with good optimization effect. |
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