EMC Analysis And Optimization Of Automobile Cooling System

After the twentieth century,the automotive industry developed rapidly,and the competition in the automotive market became increasingly fierce.According to the strategic goal of China's automobile industry development,China will develop from a big automobile consumer country to a powerful automobile industry country in 2030.Today,at the moment of advancing together "the Silk Road Economic Belt and the 21 st-Century Maritime Silk Road" strategy and the "National Brand Plan",it is an important opportunity for China's self-owned brand car to develop in high quality.With the rapid growth of the application of automotive electronic equipment in various systems of vehicles,the problem of automotive electromagnetic compatibility(EMC)is becoming more and more serious.In the traditional automotive industry,the EMC of products is gradually improved through many experiments.Because the products have already their embryonics forms,it is limited and expensive to find out the problems and then take measures to solve them.In order to solve the problem of EMC in vehicles,we should change from posteriori to prior one,effective EMC prediction of products in the early stage of vehicle design is the most important.In the first chapter introduces the basic definition of electromagnetic compatibility and the research status at home and abroad.The second chapter,the article introduces the basic knowledge used in EMC analysis,including Maxwell equation,boundary conditions of time-varying electric field,dynamic potential,Darumbell equation,and electromagnetic power flow,Poynting vector,near field,far field,reflection and crosstalk.The third chapter establishes the finite element model of the main circuit of the automotive electronic fan controller based on the theoretical knowledge,divides the model into three parts by tetrahedron element,separately establishes the finite element model of the main circuit in three connection cases,calculates the surface electric field intensity of the main circuit,analyses the electric field distribution trend,and advances the model.Experiment with the chamfering in different siezs and shapes,discusse differents effects of each processe on the surface electric field distribution of the main circuit.Chapter 4 introduces the selection of inductance,capacitance,MOS transistor and sampling resistance in the electronic fan controller.The fault feedback circuit,motor driving circuit,current sampling circuit and anti-reversal circuit inside the chip are studied respectively.The radiation experiment platform of the electronic fan controller is built by EMSAN electromagnetic interference scanning system,and the electromagnetic noise of the controller in normal operation is measured.Sound,combined with computer simulation results,the reasons for radiation emission of high power and low frequency circuits are analyzed,and some suggestions for improvement are put forward.In the fifth chapter,on the basis of introducing the radiation pattern,the far-field radiation ability of the main circuit of the electronic fan controller is analyzed,and the influence of chamfering treatment of different sizes and shapes on the far-field radiation is studied.The integrated model of the main circuit of the vehicle and the electronic fan controller is established,and the radiation ability of the chamfering model to the electric field on the surface of the car body is analyzed.The transmission line model of the fan controller control circuit is used to match the impedance of the circuit effectively,and the signal integrity simulation of the control circuit is completed by eye diagram.The results show that chamfering can reduce the surface electric field intensity of the main circuit of the electronic fan controller.The reliability of the simulation results is proved by combining the measured electromagnetic field distribution.The far-field radiation of the main circuit of the electronic fan controller and the signal integrity of the control circuit are further studied.The radiation characteristics of the main circuit are given,and the surface electric field intensity and the far-field radiation of the main circuit are verified.The emission intensity is positively correlated.Compared with the traditional qualitative analysis method,more accurate improvement measures for electronic circuits are given.