IC697CHS790通用電氣框架電磁干擾的傳輸和傳輸途徑 電磁干擾的發(fā)生必然存在干擾能量的傳播和傳播通道。干擾的傳輸有兩種基本方式：傳導和輻射。輻射耦合細分為：天線對天線耦合、場對線耦合和線對線耦合。針對干擾的傳播和耦合途徑，在汽車電器工程實踐中要采取如下的系統(tǒng)方法來改善EMC特性：濾波、屏蔽、搭鐵和布線。 2 干擾源和敏感設(shè)備的電磁兼容設(shè)計 在方案已定的功能電路中，檢驗電磁兼容指標是否滿足要求；
IC697CHS790通用電氣框架此時如不滿足要求，則可通過參數(shù)修改來達到指標，如調(diào)整數(shù)字化控制器的工作頻率、圓整脈沖的上升率或重新選擇元件等。其次進行防護設(shè)計，包括濾波、屏蔽、搭鐵與搭接設(shè)計，甚至采用時空隔離和頻率回避等改進措施。最后是做布局調(diào)整性設(shè)計，包括對總體布局的檢驗、屏蔽體縫隙的檢驗、組件和印制板布局檢驗等。電路和分系統(tǒng)的電磁兼容設(shè)計包括如下的步驟：元件選擇、電路選擇、濾波技術(shù)應(yīng)用、搭鐵設(shè)計、屏蔽設(shè)計、電路布局和系統(tǒng)布局規(guī)劃ESD防護設(shè)計 為了消除靜電放電的危害，可采取的措施有：建立完善的屏蔽結(jié)構(gòu)，通過搭鐵的金屬殼將靜電荷釋放到地；內(nèi)部電路與金屬殼的連接應(yīng)采用一點搭鐵；增加諸如硅瞬變電壓吸收二極管（STVS）之類的快速保護元件，將高壓電荷泄放到地；印制電路板設(shè)計中增加保護環(huán)帶，將人手拔插線路板的電荷通過最短的路徑泄放到地。汽車行駛記錄儀的抗干擾設(shè)計 1 汽車行駛記錄儀的硬件結(jié)構(gòu) 圖1為汽車行駛記錄儀硬件結(jié)構(gòu)原理。信號的抗干擾處理是通過光電隔離來實現(xiàn)。車載設(shè)備的電源系統(tǒng)對設(shè)備的可靠運行影響很大，好的電源電路能夠過濾掉許多通過電源線傳入的干擾信號。 2 電源部分的抗干擾設(shè)計 本控制模塊的電源電路如圖2所示。車載蓄電池—發(fā)電機的電源從24V_1處進入，二極管D16主要是防止電源的正負極被誤接反。電感L1、L2對電源進行濾波，和共模電感L3、電容C8配合，可以過濾掉電源中的尖峰脈沖。二極管D24 P6KE51A是脈沖干擾抑制器（TVS），它可以快速吸收超過額定電壓的尖峰脈沖，瞬時通過電流很大，最大功率可達500～1000W。電容E5和C9進一步對電源進行濾波。but at present, the main drainage system in coal mines is still controlled by relays. The start and stop of water pumps and the selection and switching are manually completed, and the automatic start and stop of water pumps according to the water level or other parameters cannot be achieved, which will seriously affect the management level and economic benefits of the underground main drainage pump room. Daizhuang coal mine is a modern mine with a production capacity of 1.8MT / A, which was designed and completed in 1999. The underground water inflow is large. The central pump is designed and installed with five md500-57-9 main drainage pumps, supporting motors of 1250KW, and three drainage pipelines. During normal water inrush, two are in operation, two are for standby and one is for maintenance. In view of the progressiveness and reliability of PLC, Handan Design Institute of coal industry has implemented PLC automatic control, automatic detection and dynamic display of operating parameters for five main drainage pumps and their auxiliary vacuum pumping systems and pipeline electric valves,
