Study On Electromagneticinterference Of Electric Vehiclemotor Drive System

As energy shortage and environment pollution problem increasingly serious,electric cars in recent years gradually replace traditional cars.However,compared with traditional cars,electric cars have higher integration and more electronic devices,which will bring complex electromagnetic interference problems.Due to the characteristics of high voltage,large current and complex coupling path in the motor drive system,it has become one of the main sources of electromagnetic interference in electric vehicles.In this paper,the electromagnetic interference of motor drive system is studied.Aiming at the problem of high complexity of transmission path of conduction interference in motor drive system,the conduction EMI of motor drive system is analyzed and modeled.Firstly,according to the basic theory of electromagnetic interference,the basic structure of the motor drive system,the interference source and the propagation path of the conduction interference are analyzed.Secondly,considering the mutual influence between the common mode conduction interference and the differential mode conduction interference of the motor drive system,a prediction modeling method for the conduction EMI of the motor drive system is proposed,which takes the common mode conduction interference and the differential mode conduction interference of the system as a whole.Thirdly,the modeling and simulation of conduction interference are carried out for each module in the system.Finally,an experimental platform for conducting interference of the motor drive system is built,and the experimental results are compared with the simulation results to verify the correctness and effectiveness of the prediction model of the motor drive system.Aiming at the problem that the conduction interference caused by the high voltage and large current in the motor driving system exceeds the standard limit and affects the electromagnetic environment of the whole electric vehicle,the suppression method of the system’s conduction interference is studied.Firstly,EMI filter is used to block the conduction interference propagation path of the motor driven system,and modeling and simulation are carried out.The results before and after the addition of the filter are compared,and the results show that the addition of EMI filter can effectively reduce the conduction interference of the system.Then,by changing the control strategy of the inverter of the motor driven system,the interference source of the system is suppressed and the simulation model of random switching frequency space vector pulse width modulation is established.Finally,the filter is compared with the result of using RFSVPWM control strategy,and the result shows that using RFSVPWM can effectively reduce the volume of the filter,save the cost,and even replace the filter to make the system conduction interference reach the limit range specified by the standard.Aiming at the problem that the radiation interference of the motor drive system will lead to the over-standard of the whole electric vehicle,the radiation interference of the motor drive system and the whole vehicle after loading is studied.The electric motor driving system and the radiation interference of the whole vehicle after loading were studied and the experimental platform was built.The experimental results show that although the shielding effect of the vehicle body and the difference of parts and test standards will affect the radiation interference comparison between the motor drive system and the vehicle after loading,the radiation interference of the motor drive system has a great influence on the radiation interference of the vehicle.Therefore,it is necessary to ensure that the radiation interference of the motor drive system can reach the standard range as far as possible under the qualified condition.