| While traditional fuel vehicles bring convenience to people's lives,they also have many problems,such as resource shortages and environmental pollution,which have always plagued people's lives.Wheel drive technology has been widely used in the field of electric vehicles.It has the advantages of high efficiency,convenient control and low cost.However,the narrow running space makes the heating and heat dissipation of the motor two major problems.In order to solve these problems,it is necessary to accurately calculate the loss and temperature field of each part of the motor.The first part is to explain the establishment of the motor simulation model and the study of the magnetic field characteristics of the motor,thus clarifying the accuracy of the motor model establishment.In this paper,a 25 KW external rotor permanent magnet synchronous hub motor is taken as the research object.The finite element model of the motor is established by Ansoft Maxwell software.The electromagnetic theory is used to simulate the no-load back EMF of the motor and the electromagnetic density of the air gap..The results show that the no-load back EMF curves of the three-phase windings of the motor are all sinusoidal,and the spectrum analysis is also stable.The air gap magnetic density curve shows a sinusoidal trapezoid,which proves that the motor model is established accurately.The second part is to study the loss distribution and variation law of various parts of the motor under different driving conditions,and optimize some structural parameters.Firstly,the magnetic field and loss of the motor under no-load and load conditions are studied.Secondly,the magnetic field of the motor in different working conditions such as different climbing and flat speeds is studied to study the loss distribution law of each part and discuss the limit work.The law of loss changes.Finally,the structural parameters of the motor are optimized,and the ideal motor loss is obtained.The results show that the total loss under no-load load is very different.The motor under load has high armature current,and the no-load current is almost zero.Therefore,the copper loss varies greatly;the loss of different climbing is mainly copper loss;The loss of different speeds of the flat road is mainly based on iron loss.By optimizing the structural parameters of the motor,the results show that when the length of the outer diameter of the stator is controlled between 298.4-298.7mm,the loss of the motor is low,the output torque is large,and the required motor power is low.The mouth depth is 7mm.The third part is to study the temperature field of the motor under different driving conditions and propose a heat dissipation scheme according to the maximum temperature under the extreme working conditions of the motor.Firstly,the loss calculated in the magnetic field is coupled into the temperature field in the form of heat source.The temperature rise of each part of the motor under various working conditions is simulated to find the two extreme conditions with the highest motor temperature.Secondly,an optimization scheme is proposed for the higher temperature of the motor.Finally,the actual experiment of the temperature rise of the motor at 100km/h is carried out to verify the accuracy of the simulation.The results show that the motor has the highest temperature rise at 100km/h,reaching 108°C.Add a heat pipe to the motor and add a convex groove to the motor casing to increase the heat dissipation area to reduce the motor temperature.The temperature rise of the motor is reduced by about 6 °C.From the experimental results,the maximum value of the test and simulation results does not exceed 5 ° C,and the error rate is 4%,which proves that the simulation results are more accurate. |
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