| With the emergence of energy crisis and the serious environmental pollution,the Electric Vehicle(EV)has been paid much attention to.The driving motor was required not only good magnetic design,but good cooling system.But less study of cooling fluid analysis was described in previous papers.So it was studied deeply in the paper the cooling structure and the characteristics of Computational Fluid Dynamics(CFD)fluent and heat transferring.To meet the specification of EVs,the key technologies were studied in the paper with the design and optimization of electromagnetic,fluid analysis of heat dissipation,multi-field coupling temperature distribution and mechanical stress analysis.The 30 kW PM motor was built with the peak speed of 9000r/min and the power density of 2.5kW/kg.To meet the requirement of low noise,high torque,high efficiency of motor in EVs,the pole-slot match,stator slot dimension,rotor structure,skewed slot and the lamination material for motor were analyzed by Finite Element Method(FEM).High efficiency area with speeds was very important for motor in EVs,the optimal design process was introduced of changing PM "V ?" thickness and the angle to reduce the losses.The optimal design has resulted in the account of PM material decreased 19%,and 9% reduction iron loss and 18% reduction PM loss,comparing the original design.And the optimization strategy was described as a reference for the interior PM motors.It was presented the calculation of 85 kW Tesla induction motor.The peak speed is 14000r/min.It was analyzed by magnetic circuit method and FEM,achieving the high power density of 3.5kW/kg.In order to realize the high power density of motor,reasonable electromagnetic design optimization has certain function,but good heat dissipation was the key point of design.The paper focused on the analysis and research on the cooling system using CFD.Depending on the requirements of motor,the cooling method,cooling structure,optimizing the size,cooling medium and casting shell were analyzed accordingly.Where,three types of axial,radial and spiral channels were introduced and resulted in velocity,delta pressure,and temperature distribution by CFD.And further the spiral channel was optimized with dimension ratio and shape of inlet surface.It was concluded the optimum solution and the characteristics of heat dissipation.And,the forced-air cooling structure is applied and the cooling effect was good with ingenious design.In conclusion,the liquid-cooling method was well applied in the passenger EVs,and the forced-air cooling method was fit to the commercial EVs.The above-mentioned conclusions could be as the important reference for choosing and designing cooling system of the motors in EVs.The heating dissipation effect of cooling system depended on the accurate calculation of the temperature field,which was directly related to the life and reliability of the motor.In the paper,two methods of Lumped Parameter Method(LPM)and FEM were used to calculate the temperature distribution for 85 kW induction machine.And the accuracy comparison of two methods was concluded and,the relationship between temperature on the winding end and air velocity was concluded by FEM,providing some reference for motor in EVs.Further,the mechanical stress of motor was analyzed at the speed of 9000r/min,to achieve the Multi-Domain methodology and Analysis.Finally,30 kW water-cooled permanent magnet prototype was manufactured and measured.85 kW forced-air cooling asynchronous motor as checking machine was measured.The experiment of performance and temperature rise were done for both motors.Experimental validation is presented in the paper as simulation calculation within error 5%. |
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