Research On Optimal Design Heat Sink For Motor Controller Of Pure Electric Vehicle

As the control core of pure electric vehicle,the motor controller has continuously increased the requirements for integration technology and power density.Therefore,the heat dissipation performance will directly affect the reliability of the vehicle’s electric drive system.The main work of this paper is to take the original prototype of the MOS multi-transistors parallel motor controller as the research object,and set the reduction of temperature rise of the MOS transistor chip and the lightweight of the fin heat sink as the optimization design goals.The design idea of increasing convective heat transfer surface area and heat transfer coefficient of the single fin to improve the heat dissipation capacity of the single fin was adopted.The original smooth fin was replaced by a cross multi-ribs fin,and a single fin was added with a plurality of small ribs distributed as a design scheme to optimize the structure of the cross-rib fin heat sink.Firstly,CFX thermal simulation analysis model was built,and a temperature rise experiment was carried out on the towing test-bench of the electric drive system.The results showed that the error between thermal simulation analysis and temperature rise experiment was less than 5%,which verifies the accuracy of CFX thermal simulation analysis model.Secondly,using multi-objective optimization algorithm,combined with the numerical analysis of the mixed-level orthogonal arrays experiments,the prediction model of BP neural network and the global optimization of NSGA-Ⅱ multi-objective genetic algorithm,the multi-objective optimization design of the cross multi-ribs fin heat sink was carried out to find the Pareto optimal solution set.A representative design solutions of multi-ribs fin were selected for thermal simulation analysis.The results showed that the error between the predicted value of the multi-objective optimization algorithm and the result of thermal simulation analysis was less than 3%,which verifies the accuracy and effectiveness of the multi-objective optimization algorithm.At the same time,it is verified that the temperature rise of MOS transistor chip and the weight of fin heat sink are mutually restricted and affected,and cannot reach the optimal value at the same time.Compare with the somooth fin,the cross-rib fin structure increases the convective heat dissipation surface area and heat transfer coefficient values of a single fin.Finally,the parameter analysis was performed on the design solutions in the optimization solution set,and the design solutions in the optimization solution set can all reach the optimization design goal.One of the design solutions was selected and compared with the original prototype for thermal simulation analysis.The temperature rise of the MOS transistor chip was ruduced by 0.21%,and the weight of the fin heat sink was reduced by 9.04%.Prototype machining and temperature rise test were performed on this design solution.The results show that the error between the thermal simulation analysis and temperature rise test is less than 5%,which verifies the accuracy of CFX thermal simulation analysis model again.