| With the development of modern electronics and automotive electronics technology , more and more electronic products are widely used in cars.Although these electronic products make vehicles economic, safety and comfort , automotive EMC issues become more and more complex,.Automotive EMC must be considered in modern car's designed The wiper system is important source in EMC to in automobile. It has a major impact to automotive EMC.On one hand, wiper motor can produce electromagnetic interference which has high and wide band during normal working time. On the other hand, Wiper Motor increase substantial interference to equipments in vehicles while electronic components and modules are widely used in automobile nowadays, and the working voltage of electronic devices gradually decrease .Wiper Motor is also an important reason that vehicle can not satisfy stringent EMC criteria.so it is has an important value and practical significance for us to research automobile EMC of window wiper systemSupported by the National Natural Science Foundation"the prediction of Automotive EMC and research to the key technologies of electromagnetic interference suppression"(NO: 50877081),Natural Science Foundation Project of Chongqing, The EMC Study of Auto Electrical System (NO: CSTC, 2006BA6015), conducted EMI and radiated EMI which is producted by wiper motor in working time, and the associated suppression measures, are considered as the focuses, then simulation and experiments are conducted, the main work is listed below:①The principle of automotive's wiper system,the basic structure of wiper motor, and electromagnetic theory involved in simulation, are all analyzed ,which establish the theoretical foundation to the research.②The conducted EMI to Wiper Motor Intermittent stall is simulated .The working of intermittent stall is the key .The mechanism of generating conducted EMI in intermittent stall is analyzed deeply,and the conduction EMI source– transient pluse voltage,which productes while motor is disconnected, is measured. Combine high-frequency equivalent circuit model of motor windings when the impact of high-frequency electromagnetic parameters is considered ,the simulation model of motor conducted EMI is established On this basis, wiper motor's conducted EMI in intermittent stall is predicted. ③The mechanism of radiation EMI and radiation path was analyzed , wiper motor's radiation EMI model in vehicle-level can be get according to calculating radiation transfer function of wiper motor and measuring the conducted voltage of wiper motor.On this basis ,the simulation to wiper motor's radiated EMI was done in the level of vehicle.And the radiated EMI are measured in an anechoic chamber which is located in the research center of EMC, Chongqing. Simulation is consistent with experimental results ,which indicate that the modeling and the method of simulation are correct.④The commonly measures of suppressing EMI which is shielding, filtering, grounding are analysed, then effective measures to improve wiper motor's EMC environment and reduce EMI are instructed.⑤The filtering theory of ferrite filters is analysed . Considering the impact of ferrite choke's distributed inductance and winding's couple capacitance, which are the distribution electromagnetic parameters in high-frequency, high-frequency equivalent circuit model is established, which is combined with equivalent circuit parameters we can get by impedance analyzer .On this basis, high-frequency ferrite filter equivalent circuit model is established ,then a simulation and further characterization's analysis are intruducted in the example of intermittent stall.⑥Experiments to the filter is operated in the example of wiper motor's high-speed stall and low-speed stall.The experimental is consistent with the simulation from the trend and the feature of rejection , which shows that the method to simulate and model is corrent.
|
PDF Full Text Request