Calculation Of Temperature Field And Optimization Design Of Oil Circuit Structure Of Motor With Hairpin Windings For New Energy Vehicles

With its advantages of high power density and high torque density,the motor with hairpin windings is widely used in the drive motor of new energy vehicles.However,with the increase of power density and torque density,the caloric value of the motor will also increase.In order to ensure the safe and stable operation of the vehicle,the motor usually adopts the oil-cooling mode with efficient cooling ability.Therefore,the oil-cooled motor with hairpin windings has become one of the research hotspots of the new-energy vehicle motor.In this dissertation,an oil-cooled motor with hairpin windings is taken as an example,the finite element method was used to study its electromagnetic performance,and the oil circuit structure was designed and optimized,and the influence of the oil circuit structure on the temperature rise of the motor was studied through the simulation of fluid field and temperature field.In order to study the electromagnetic and thermal performance of oil-cooled motor with hairpin windings,an 8-pole,48-groove oil-cooled motor with hairpin windings was established in this dissertation.The electromagnetic performance of the motor under no-load and load conditions was calculated and analyzed.On the basis of meeting the requirements of performance indexes,the motor was further optimized with the goal of reducing the cogging torque and torque ripple.The rotor structure with6 segments of "V-shaped" skew pole was finally determined by comparing and analyzing the "linear" and "V-shaped" rotor segment skew pole,and the electromagnetic performance of the motor was improved after calculation and analysis.In order to study the temperature rise in the motor,this dissertation firstly calculated and analyzed the loss of each part of the motor.Since the magnetic field distribution of the position of the end winding and the slot winding is different,when the finite element method was used to calculate the AC loss of the end winding,only the winding part of the motor was reserved to simulate the magnetic field of the end,so as to obtain a more accurate AC loss of the winding.Design the motor oil circuit structure,through the motor fluid field simulation calculation,study the motor internal cooling oil distribution.In order to improve the calculation efficiency of the temperature field,the 3D equivalent calculation model of the motor temperature field was established,and the influence of the cooling structure on the temperature rise of the motor was analyzed based on the simulation results of the temperature field.By analyzing the simulation results of the motor fluid field and temperature field,the optimized parts of the oil circuit structure were determined.Taking the balanced distribution of cooling oil as the optimization objective,the optimization parameters were reasonably selected,the orthogonal experimental matrix was designed,the oil circuit structure was optimized by Taguchi method,and the motor oil circuit structure was modified according to the dimensions of each part of the optimal results in the experimental matrix.Then the temperature field of the motor was simulated after optimization,and the temperature rise of the motor before and after optimization was compared and analyzed.The rationality of the optimized oil circuit structure was verified.