外文翻译--解析有效的开关电源电磁干扰的抑制措

Analyze the valid switch power supply electromagnetism interference represses the measureTake off to want: This text analyzes the switch power supply to produce the mechanism of the electromagnetism interference first, a few valid switches power supply electromagnetism interference measure carried on the analysis currently comparison, and put forward the reference suggestion for the further research of the switch power supply electromagnetism interferenceKeyword: The switch power supply electromagnetism interference represses the measure to matchCurrently, many universities and the research units all carried on the research of the switch power supply EMI( the Electromagnetic Interference), they win some mechanism that produces from the EMI to set out, some from the EMI produce of influence set out, all put forward many practical worthy projects.The here is analytical with compared a few valid projects, and repress the measure to put forward the new reference suggestion for the switch power supply EMI.One，the creation mechanism of the switch power supply electromagnetism interferenceOutput interference of the switch power supply, press an interference of source category to divide, can is divided into the diapason an interference of the peak interference two kinds of； if match the thoroughfare according to the to divide, can is divided in to conduct the interference and radiation the interference is two kinds of.Press an interference of source to come to explain respectively now:1, diode of anti- toward the interference that the instauration time causeThe high commutates the back track in of commutate a hour of positive guide of diode to is bigger just flow through toward electric current, at it be subjected to anti- be partial to the electric voltage but change direction to close, because having to carry to flow the sub- backlog morely in the PN knot, as a result in carry flow sub- disappearance previously of a period of time, the electric current would be anti- toward fluxion, causing carry to flow the sub- disappearance anti- to reduce toward nasty play of the instauration electric current but take place the very big electric current variety( di/ dt).2, an interference of that hour of work produce of tube of switchThe power switch tube flows through the bigger pulse electric current while lead.For example just arouse the type and push a form of the importation electric current of the type of and the bridge type transformation machine at the load look like for the rectangle wave, among them imply a weight of abundant high .When adopt zero electric currents, zero electric voltage switcheses, an interference of this kind of will be very small.Moreover, the power switch take care of during the period of close, the high transformer of rounds an electric current mutation for leaking the feeling to cause, also will produce the peak interference.3, exchanges importation interference of the back track creationThe switch power supply importation that have no work transformer carries to commutate the tube at anti- will cause the high to reduce to flap to become bankrupt to living the interference toward period of instauration.Harmonious interference energy of the switch power supply output peak interference, the importation that passes the switch power supply outputs the line dissemination to go out but the formative interference call it as to conduct the interference； but wave of and live on the energy of flap the 荡 , pass the importation exportation line dissemination, will produce the electric field and magnetic fields in the space.This kind of is called the radiation interference through an output interference of the electromagnetism radiation.4, other reasonA machine piece lives on the parameter, the principle diagram of the switch power supply design not enough perfect, the printing circuit plank( PCB) walk the line usually adopts the handicraft to arrange, have very big at will sex, the PCB an interference is big, and print the plank up the gearing of the machine piece, place, and directions of not reasonable will result in the interference of EMI.Two, the characteristics of the switch power supply EMIBe the work in the energy conversion device of the switch appearance, the electric voltage, the electric current variety rate of the switch power supply is very high, the interference strength that produce compare greatly；The interference source main the concentration is in the power switch period and spread the hot machine and high and even transformers connect with each other with it, opposite compare in the position of the numerical electric circuit interference source clearly；The switch frequency is not high( from several:, and the few trillion Hertzs), the main interference form is to conduct the interference and an interferences； but the printing circuit plank( PCB) walk the line usually adopts the handicraft cloth line, have larger at will sex, this difficulty that increases the PCB to distribute the parameter to withdraw to estimate with an interference.Three, the EMI test techniqueExamine a patient three kinds of methods of the total mold interference of bad mold currently:The radio frequency electric current stretch forward, the bad mold represses the network, the voice to separate the network.Stretch forward with the radio frequency electric current is to measure bad mold total the most simple method in the mold interference, but measure result limit value with standard to relatively want has been converted complicatedly more.The bad mold represses the network structure simple( see the figure 1), measure the result and can limit the value comparison with standard directly, but can measure the total mold interference only.The voice separates the network is the most ideal method, but the manufacturing of its key parts transformer have very high request.Four, repress a few measure of the interference currentlyThree main factors that become the electromagnetism interference are interferences sources, the dissemination paths and is subjected to the equipments of .As a result, repressing the electromagnetism interference also should begin from these three aspects.Should repress the interference source first, the direct cancellation interference reason； is a that removes the interference source and is by the equipments of to match and radiate the next in order, cut off the dissemination path( see the figure 2) of the electromagnetism interference； the third is the exaltation be subjected to the equipments of of the anti- ability, turn down it to the sensitive degree of the voice of .Repress a few measure of the interference currently is all a that uses to cut off the electromagnetism interference source and be by the equipments of to match the passage basically, they are valid way that gos indeed.The in common use method is to shield, connect the ground and wave of .The adoption shields the electromagnetism radiation interference that the technique can repress the switch power supply availably.For example, the power switch tube and the exportation diodes usually have the bigger power to exhaust, for spread hot usually need to install to spread the hot machine or direct gearings on the power supply scaleboard.Need to transmit heat the function to like when the machine piece install of insulate the slice to carry on insulate, this make the machine piece and scaleboard and spread the hot machine of a creation distribute the electric capacity, the scaleboard of the switch power supply is a line of the AC power, as a result distribute the electric capacity to match the electromagnetism interference to the exchanges importation to carry the total mold interference of creation through the machine piece and of the scaleboards, the way that resolves this problem is to adopt two layers insulate the slice of clip a layer to shield the slice, and shield the slice to receive the direct current ground up, cut off the radio frequency interference toward the path of the importation charged barbed wire net dissemination.For repressing the output radiation of the switch power supply, the electromagnetism interference as to its the influence of his electronics equipments, can completely according to process to shield the cover to the method that the magnetic field shield, then carry on the whole machine hull and a conjunctions that shields the cover and system are an integral whole, ability to the electromagnetism field effectively to shield.Some parts of power supply and the earths connect with each other the function that can rise to repress the interference.For example, the static electricity shield the layer connect a ground of can repress to change the electric field of interference； the conductor that electromagnetism shields to use can not connect the ground in principle, but dont connect the ground to shield the conductor to often strengthen the static electricity to match but produce so-called the negative static electricity shield effect, so still take connecting the ground as to like, making electromagnetism shield thus can develop the function that static electricity shield at the same time.The public reference point and the earths of the electric circuit connect with each other, can provide the stable reference electric potential for the signal back track.Therefore, the protection a line of safety in the system, shield to connect a ground of line and a line of public references each after formation connected a ground of female line, end all connect with each other with the earth.Should follow the principle of connect the ground 1:00 in the electric circuit system design, if the formation orders to connect the ground much, will appear to shut to match of connect the ground wreath road, be the line of magnetic force to cut through the hour of that back track and will produce the to respond the voice of , the actually very difficult realization connect the ground 1:00.Therefore, in order to lower to connect a ground of resistance, the cancellation distributes the influence of the electric capacity but adopts the flat surface type or orders to connect the ground much, make use of a conducts electricity the flat surface( scaleboard or many the layer prints to make the plank electric circuit to conduct electricity the flat surface layer etc.) conduct and actions reference ground, each part that needs to connect the ground receives close at hand and should consult the ground up.In order to further let up to connect a ground of back track to press to decline, can reduce a value of return the electric current with the bypass electric capacity.In the electric circuit system that low frequency and high coexist, after should distinguish to link a line of the low frequency electric circuit, high electric circuit of , the power electric circuit alone, then link the public reference to order up. The wave of is a kind of good way that represses to conduct the interference.For example, input to carry to mount the filter in the power supply, can repress the switch power supply creation to combine toward interference of the charged barbed wire net feedback, can also repress the voice of of come from the charged barbed wire net to violate to the power supply.In an electric circuit of , still adopt a component of a lot of appropriative , if wear the heart capacitor, three carry the capacitor, the iron oxygen body wreath, they can improve a characteristic of of the electric circuit.Design or choose the filter fittingly, and install and use the filter with accuracy, is a technical importance of the anti- interference to constitute the part.A technique of the EMI is a kind of valid measure that represses the sharp pulse interference, can with in addition to various conduction interference with output reason.Figure 3 is a kind of filter of EMI that be constitute by the electric capacity, the electricity feeling, connect in the switch power supply of importation carry.In the electric circuit, the C1, C5 is the high bypass electric capacity, used for the divided by two the importation power cable of bad mold interference； L1 and C2, C4； the L2 and C3, C4 constitutes a link of the total mold interference , useding for the in addition to the power cable and a not symmetry total mold interference of the ground； the first time class full circle number of the L3, L4 is equal, the pole is contrary, communicate the electric current is in the the output of is contrary, as a result can repress the total mold interference availably.The test express that want only the parameter of the appropriate choice a machine piece, can compare to repress the output conduction interference of the switch power supply goodly then.Five, the switch power supply EMI represses the place of the shortage of the measure currentlyRepress the measure existingly to match and radiate from the that remove the interference source and be by the equipments of 扰 mostly, the dissemination path that cuts off the electromagnetism interference set out, this is the valid way that repress the interference a kind of to go indeed, but few someone involves the direct control interference source, the cancellation interference, or the exaltation be anti- by the equipments of the ability, hardly realizing the latter still has many spaces of development.Six, the suggestion of the improvement measureI thought to set out to repress the interference currently from the dissemination path of the electromagnetism interference, have already entered the maturity gradually.We see to order to return to the switch power supply machine piece.Practiced from the work of many years to see, at the electric circuit wants to notice the following what time:(1)While printing to make the plank layout, want will imitate the electric circuit area and numerical electric circuit areas to separate reasonably, the power supply and a lines are alone the derivation, the power supply supplies the place to gather together till 1:00； the cloth line, the numerical signal line of high wants to use the short line, the main signal line is best concentrated in the plank center, the power cable keeps off the numerical signal line of high possibly at the same time or partitions with a line.The next in order, can match the coefficient to come to the cloth line according to the , reduce the interference to match(2) to print to make the knothole power cable and a lines to print to make as far as possible possibly breadth, to let up the line resistance, thus let up the interference voice that the public resistance cause.(3)The machine piece chooses to use to stick a slice of component much and shortens the component to lead the feet length possibly, to let up the component to distribute the influence of give or get an electric shock the feeling.(4)Carry to close to the machine piece to connect into an electric capacity of possibly in the Vdd and power supply of Vcc, to shorten the switch electric current to circulate the path, such as merge to connect on the power supply feet with 10 aluminum electrolysises and 01 electric capacity of ss.Can replace the aluminum electrolysis electric capacity with the electrolysis electric capacity for the power supply of the high-speed numerical carry, because the 钽 electrolysis is smaller than the aluminum electrolysis and have to have another to a resistance.Knot theoryFactor that produces the switch power supply electromagnetism interference still a lot of, repress the electromagnetism interference to still have a great deal of work.Repress various voice of of the switch power supply and will make the switch power supply get the more extensive application completely解析有效的开关电源电磁干扰的抑制措施摘 要： 本文先分析了开关电源产生电磁干扰的机理, ,就目前几种有效的开关电源电磁干扰措施进行了分析比较，并为开关电源电磁干扰的进一步研究提出参考建议。关键词： 开关电源 电磁干扰 抑制措施 耦合 目前，许多大学及科研单位都进行了开关电源EMI（Electromagnetic Interference）的研究，他们中有些从EMI产生的机理出发，有些从EMI 产生的影响出发，都提出了许多实用有价值的方案。这里分析与比较了几种有效的方案，并为开关电源EMI 的抑制措施提出新的参考建议。一、开关电源电磁干扰的产生机理开关电源产生的干扰,按噪声干扰源种类来分,可分为尖峰干扰和谐波干扰两种；若按耦合通路来分,可分为传导干扰和辐射干扰两种。现在按噪声干扰源来分别说明：1、二极管的反向恢复时间 的干扰 路中的 二极管 向导通时有较大的 向电 ,在 反 电 向 时, PN 中有较多的 , 在 前的一 时间里,电 反向 , 的反向恢复电 发生大的电 (di/dt)。2、开关管currency1时产生的谐波干扰 “开关管在导通时 较大的电 。fifl 、和 的电 波”在 时 为 ”波, 中有的 谐波分。用电 、电 开关时,这种谐波干扰 。 ,“开关管在 间, 的电 , 产生尖峰干扰。3、 路产生的干扰 currency1 的开关电源 管在反向恢复间 荡产生干扰。开关电源产生的尖峰干扰和谐波干扰 ,通 开关电源的出 传 出” 的干扰 为传导干扰； 谐波和 生 荡的 ,通 出 传 时,都 在 间产生电和磁。这种通 电磁辐射产生的干扰 为辐射干扰。4、 他 的 生参 ，开关电源的 理 ， 路 （PCB）通用 currency1 ，有大的 ，PCB的 干扰大，并 的、 ， 及方位的合理都 EMI干扰。二、开关电源EMI的 点为currency1 开关状态的 ，开关电源的电 、电 ，产生的干扰强度较大；干扰源主要集中在“开关间 及与 相连的散热和 平 ，相对 字电路干扰源的位 较为清楚；开关 （从几十千赫和 兆赫兹），主要的干扰” 是传导干扰和 干扰； 路 (PCB) 通用 currency1 ,有更大的 ,这增加了PCB分 参 的提取和 干扰估的难度.三、EMI测试技术目前诊断差模共模干扰的三种方法：射 电 探头、差模抑