【正文】 , power density has also been boosted, dynamic response improved. Small power DC DC converter switch frequency will rise to MHz. But as the switch frequency unceasing enhancement, switch ponents and passive ponents loss increases, highfrequency parasitic parameters and highfrequency EMI and so on the new issues will also be caused. （2）Soft switching technologies: in order to improve the efficiency of nonlinearity of various soft switch, mutation technical application and hygiene, representative of soft switch technology is passive and active soft switch technology, mainly including zero voltage switch/zero current switch (ZVS/ZCS) resonance, quasi resonant, zero voltage/zero current pulse width modulation technology (ZVS/ZCS PWM) and zero voltage transition/zero current transition pulse width modulation (PWM) ZVT/ZCT technical, etc. By means of soft switch technology can effectively reduce switch loss and switch stress, help converter transformation efficiency （3）Power factor correction technology (IC simplifies PFC). At present mainly divided into IC simplifies PFC technology passive and active IC simplifies PFC technology using IC simplifies PFC technology two kinds big, IC simplifies PFC technology can improve AC DC change device input power factor, reduce the harmonic pollution of power grid. （4）Modular technology. Modular technology can meet the needs of the distributed power system, enhance the system reliability. （5）Low output voltage technology. With the continuous development of semiconductor manufacturing technology, microprocessor and portable electronic devices work more and more low, this requires future DC DC converter can provide low output voltage to adapt microprocessor and power supply requirement of portable electronic devices People in switching power supply technical fields are edge developing related power electronics device, the side of frequency conversion technology, development of switch between mutual promotion push switch power supply with more than two year growth toward light, digital small, thin, low noise and high reliability, antiinterference direction. Switching power supply can be divided into the AC/DC and DC/DC two kinds big, also have AC/AC DC/AC as inverter DC/DC converter is now realize modular, and design technology and production process at home and abroad, are mature and standardization, and has approved by users, but the AC/DC modular, because of its own characteristics in the process of making modular, meet more plex technology and craft manufacture problems. The following two types of switch power supply respectively on the structure and properties of this. Switching power supply is the development direction of high frequency, high reliability, low consumption, low noise, antijamming and modular. Because light switch power, small, thin key techniques are changed, so high overseas each big switch power supply manufacturer are devoted to the development of new high intelligent synchronous rectifier, especially the improvement of secondary devices of the device, and power loss of Zn ferrite (Mn) material? By increasing scientific and technological innovation, to enhance in high frequency and larger magnetic flux density (Bs) can get high magnetic under the miniaturization of, and capacitor is a key technology. SMT technology application makes switching power supply has made considerable progress, both sides in the circuit board to ensure that decorate ponents of switch power supply light, small, thin. The high frequency switching power supply of the traditional PWM must innovate switch technology, to realize the ZCS ZVS, soft switch technology has bee the mainstream of switch power supply technical, and greatly improve the efficiency of switch power. For high reliability index, America39。任何電子設(shè)備都離不開可靠的電源，它們對(duì)電源的要求也越來越高。傳統(tǒng)的晶體管串聯(lián)調(diào)整穩(wěn)壓電源是連續(xù)控制的線性穩(wěn)壓電源。但通常都需要體積大且笨重的工頻變壓器與體積和重量都很大的濾波器。在近半個(gè)世紀(jì)的發(fā)展過程中，開關(guān)電源因具有重量輕、體積小、效率高、穩(wěn)壓范圍寬等優(yōu)點(diǎn)，在電子電氣、控制、計(jì)算機(jī)等許多領(lǐng)域的電子設(shè)備中得到了廣泛的使用。二十世紀(jì)九十年代，開關(guān)電源在電子、電器設(shè)備、家電領(lǐng)域得到了廣泛的應(yīng)用，開關(guān)電源技術(shù)進(jìn)入快速發(fā)展期。功率開關(guān)管、PWM控制器和高頻變壓器是開關(guān)電源必不可少的組成部分。七十年代以來，涌現(xiàn)出許多功能完備的集成控制電路，使開關(guān)電源電路日益簡化，工作頻率不斷提高，效率提高，并為電源小型化提供了廣闊的前景。采用TOP開關(guān)集成電路設(shè)計(jì)開關(guān)電源，可使電路簡化，體積進(jìn)一步縮小，成本也明顯降低。美國PI(Power Integration)公司于上世紀(jì)九十年代中期率先推出的新型高頻開關(guān)電源芯片，被譽(yù)為頂級(jí)開關(guān)電源，具有成本低，電路簡單，效率高等優(yōu)點(diǎn)。上述產(chǎn)品一經(jīng)問世便顯示出強(qiáng)大的生命力，他極大地簡化了150W以下開關(guān)電源的設(shè)計(jì)和新產(chǎn)品的開發(fā)工作，也為新型、高效、低成本開關(guān)電源的推廣與普及創(chuàng)造了良好條件，可廣泛用于儀器儀表、筆記本電腦、移動(dòng)電話、電視機(jī)、VCD和DVD、攝錄像機(jī)、手機(jī)電池充電器、功率放大器等領(lǐng)域，并構(gòu)成各種小型化、高密度、在價(jià)格上能與線性穩(wěn)壓電源相競爭的AC/DC電源變換模塊。 （1）高頻化技術(shù)：隨著開關(guān)頻率的提高，開關(guān)變換器的體積也隨之減少，功率密度也得到大幅提升，動(dòng)態(tài)響應(yīng)得到改善。但隨著開關(guān)頻率的不斷提高，開關(guān)元件和無源元件損耗的增加、高頻寄生參數(shù)以及高頻EMI等新的問題也將隨之產(chǎn)生。采用軟開關(guān)技術(shù)可以有效的降低開關(guān)損耗和開關(guān)應(yīng)力，有助于變換器變換效率的提高。目前PFC技術(shù)主要分為有源PFC技術(shù)和無源PFC技術(shù)兩大類，采用PFC技術(shù)可以提高ACDC變化器輸入端功率因數(shù)，減少對(duì)電網(wǎng)的諧波污染。采用模塊化技術(shù)可以滿足分布式電源系統(tǒng)的需要，提高系統(tǒng)的可靠性。隨著半導(dǎo)體制造技術(shù)的不斷發(fā)展，微處理器和便攜式電子設(shè)備的工作越來越低，這就要求未來的DCDC變換器能夠提供低輸出電壓以適應(yīng)微處理器和便攜式電子設(shè)備的供電要求。開關(guān)電源可分為AC/DC和DC/DC兩大類，也有AC/AC DC/AC 如逆變器 DC/DC變換器現(xiàn)已實(shí)現(xiàn)模塊化，且設(shè)計(jì)技術(shù)及生產(chǎn)工藝在國內(nèi)外均已成熟和標(biāo)準(zhǔn)化，并已得到用戶的認(rèn)可，但AC/DC的模塊化，因其自身的特性使得在模塊化的進(jìn)程中，遇到較為復(fù)雜的技術(shù)和工藝制造問題?！　￠_關(guān)電源的發(fā)展方向是高頻、高可靠、低耗、低噪聲、抗干擾和模塊化。SMT技術(shù)的應(yīng)用使得開關(guān)電源取得了長足的進(jìn)展，在電路板兩面布置元器件，以確保開關(guān)電源的輕、小、薄。對(duì)于高可靠性指標(biāo)，美國的開關(guān)電源生產(chǎn)商通過降低運(yùn)行電流，降低結(jié)溫等措施以減少器件的應(yīng)力，使得產(chǎn)品的可靠性大大提高。針對(duì)開關(guān)電源運(yùn)行噪聲大這一缺點(diǎn)，若單獨(dú)追求高頻化其噪聲也必將隨著增大，而采用部分諧振轉(zhuǎn)換電路技術(shù)，在理論上即可實(shí)現(xiàn)高頻化又可降低噪聲，但部分諧振轉(zhuǎn)換技術(shù)的實(shí)際應(yīng)用仍存在著技術(shù)問題，故仍需在這一領(lǐng)域開展大量的工作，以使得該項(xiàng)技術(shù)得以實(shí)用化。要加快我國開關(guān)電源產(chǎn)業(yè)的發(fā)展速度，就必須走技術(shù)創(chuàng)新之路，走出有中國特色的產(chǎn)學(xué)研聯(lián)合發(fā)展之路，為我國民經(jīng)濟(jì)的高速發(fā)展做出貢獻(xiàn)。首先將此電源視為一個(gè)復(fù)雜的電子系統(tǒng)工程，視為由幾個(gè)子單元組成的較大電子系統(tǒng)。1）對(duì)于關(guān)鍵元器件，采用并聯(lián)方式，保證此單元有足夠的冗余度如圖2所示的RR6；CC11。3）在同等體積下盡量采用高額度的元器件例如TVLLL3。5）原則上不選用電解質(zhì)電容盡量選用無極性介質(zhì)電容。6）沒有接線或連接器采用厚膜混合技術(shù)。上述七個(gè)方面便是此電源選用元器件的原則。表7電流反饋單端正激式電源和電壓反饋推挽式電源的比較電流反饋單端正激式電源電壓反饋推挽式電源元器件數(shù)少較多工作頻率提高容易（最高可大于800kHz）不容易（250kHz）高低溫穩(wěn)定性很好一般功率密度較高低工作應(yīng)力較小大振蕩過沖很小較大過流保護(hù)自帶外加從表7的對(duì)比我們不難看出，電流反饋單端正激式的突出優(yōu)點(diǎn)在于1）高頻率工作下的低應(yīng)力；2）同樣功率的電源所用的元器件較少；3）因?yàn)槠錇殡娏鞣答伿?，使其先天地具有高、低溫穩(wěn)定性強(qiáng)于電壓反饋式的優(yōu)點(diǎn)。DC/DC變換器集成電路及應(yīng)