同步整流技術(shù)分享_圖文

1、江蘇宏微科技股份有限公司 Power for the Better 同步整流技術(shù)及主要拓?fù)潆娐?宏微科技市場部 2015-9-16 Contents 同步整流電路概述 典型電路及其特點(diǎn) 損耗分析 同步整流電路中常見問題 MOSFET選型設(shè)計(jì)參考 Power for the Better 1 CONFIDENTIAL 力 求 更 好 Contents 同步整流技術(shù)概述 典型電路及其特點(diǎn) 損耗分析 同步整流電路中常見問題 MOSFET選型設(shè)計(jì)參考 Power for the Better 2 CONFIDENTIAL 力 求 更 好 同步整流技術(shù)概述 由于中低壓MOSFET具有很小的導(dǎo)通電阻，在有

2、電流通過時(shí)產(chǎn)生的電壓降很 小，可以替代二極管作為整流器件，可以提高變換器的效率。 diode MOSFET MOSFET作整流器時(shí)，柵源極間電壓必須與被整流電壓的相位保持同步關(guān)系才 能完成整流功能，故稱同步整流技術(shù)。 MOSFET是電壓控制型開關(guān)器件，且沒有反向阻斷能力，必須在其柵-源之 間加上驅(qū)動(dòng)電壓來控制器漏-源極之間的導(dǎo)通和關(guān)斷。這是同步整流設(shè)計(jì)的難 點(diǎn)和重點(diǎn)。 根據(jù)其控制方式，同步整流的驅(qū)動(dòng)電路分為 自驅(qū)動(dòng)方式； 獨(dú)立控制電路他驅(qū)方式； 部分自驅(qū)+部分他驅(qū)方式結(jié)合； Power for the Better 3 CONFIDENTIAL 力 求 更 好 Contents 同步整流技術(shù)概

3、述 典型電路及其特點(diǎn) 損耗分析 同步整流電路中常見問題 MOSFET選型設(shè)計(jì)參考 Power for the Better 4 CONFIDENTIAL 力 求 更 好 1m C11u L12R11u L2P 1S1TX1DC-AC Converter D1N4148D21m C12u L12R12u L2DC-AC ConverterP 1S1S2TX1D1N4148D1主變壓器副邊繞組自驅(qū)動(dòng)輔助繞組自驅(qū)動(dòng)自驅(qū)同步整流電路1m C24u L42R2DC-AC ConverterP 1S1S2S3TX2DC-AC ConverterP 1S1TX22R24u L41m C2主變壓器副邊繞組自驅(qū)

4、動(dòng)輔助繞組自驅(qū)動(dòng) CONFIDENTIAL 7Power for the Better 他驅(qū)方式優(yōu)點(diǎn):易實(shí)現(xiàn)符合同步整流需要的驅(qū)動(dòng)時(shí)序邏輯;易獲取高效率;外圍電路較簡單;在反激,對(duì)稱半橋,全橋,LLC拓?fù)鋺?yīng)用廣泛。缺點(diǎn):需要驅(qū)動(dòng)IC; 成本較高。Contents同步整流技術(shù)概述典型電路及其特點(diǎn)損耗分析 CONFIDENTIAL8Power for the Better同步整流電路中常見問題MOSFET 選型設(shè)計(jì)參考同步整流管損耗考慮A SR MOSFET does not use activeswitching switching speed has no primary relevance

5、and has no influence on efficiency! CONFIDENTIAL9Power for the BetterLosses in a SR MOSFET come fromConduction losses (like in a diodeBody diode conduction losses(dead timeGate drive losses (not present with diodesReverse recovery losses (like in a diode, but typically larger同步整流管損耗考慮 Conduction Con

6、ducting losses Pv _ cond = I Body diode conduction loss 2 RMS RDS ( on PV _ BD _ cond = VD I D t BD _ on f sw Gate losses Switching Pv _ gate = Qg Vg f sw Turn-off reverse recovery losses Psw = VT (1 2 Qoss + Q *rr f sw Power for the Better 9/17/2015 力 10 CONFIDENTIAL 求 更 好AOS Confidential 10 同步整流管損

7、耗考慮 Upeak I comm Utrafo Qoss di/dt=const Irev_ peak tIpeak trev tUpeak Qrr* UDS ID time MOS body diode 反向恢復(fù)電壓，電流簡化波形和實(shí)測波形 Coss 8 7 6 Coss nF 5 4 3 2 1 0 0 10 20 30 40 50 Uds V 60 70 80 90 100 Coss Coss_mean Qoss = coss (t v(t dt = VT Cconst Cconst 0 UT 1 T = coss (t v(t dt VT 0 U Power for the Bette

8、r 11 CONFIDENTIAL 力 求 更 好 同步整流管損耗考慮 80V MOSFET technology; transformer output 40V; Vout = 12V Power Losses per SR MOSFET Switching Frequency - 125kHz 4.0 3.5 power dissipation W Qrr/Mosfet Qoss/Mosfet Diode/Mosfet Qg/Mosfet Conduction/Mosfet 3.0 2.5 2.0 1.5 1.0 0.5 0.0 10 30 output current A 50 Powe

9、r for the Better 12 CONFIDENTIAL 力 求 更 好 同步整流管損耗考慮 Synchronous rectification yields a major efficiency gain MOSFETs have lower conduction losses but higher switching losses than diodes Turn-off losses should be minimized by Lowering the transformer voltage Using MOSFETs with a low voltage-class Usin

10、g packages with a low contribution to Rds(on Correctly selecting the Rds(on Power for the Better 13 CONFIDENTIAL 力 求 更 好 Contents 同步整流技術(shù)概述 典型電路及其特點(diǎn) 損耗分析 同步整流電路中常見問題 MOSFET選型設(shè)計(jì)參考 Power for the Better 14 CONFIDENTIAL 力 求 更 好 驅(qū)動(dòng)時(shí)序一旦不同步易引起效率降低(驅(qū)動(dòng)開通延遲,MOS 體二極管導(dǎo)通時(shí)間增加和電流倒灌現(xiàn)象(驅(qū)動(dòng)關(guān)斷延遲對(duì)于主變壓器繞組電壓非互補(bǔ)的拓?fù)渲?例如半橋,全橋

11、,存在較長的死區(qū)時(shí)間,導(dǎo)致采用自驅(qū)電路的MOS驅(qū)動(dòng)電壓不足或沒有,效率降低;需要采取柵荷保持技術(shù); CONFIDENTIAL15Power for the Better驅(qū)動(dòng)繞組電壓受變壓器漏感影響,驅(qū)動(dòng)波形不可避免有一定尖峰電壓,降低可靠性;自驅(qū)電路所用的繞組電壓幅值隨占空變化較大,容易超過Vgs 限值而損壞MOS管,需要增加由一個(gè)MOS管組成的正-負(fù)限幅電路; 上述增加的正-負(fù)限幅電路會(huì)增加驅(qū)動(dòng)損耗,還會(huì)增加主功率MOS管的導(dǎo)通和關(guān)斷時(shí)間,從而降低效率;輔助繞組如果帶中心抽頭,則有驅(qū)動(dòng)負(fù)壓,增加驅(qū)動(dòng)損耗; 整流管和續(xù)流管的驅(qū)動(dòng)電壓在切換時(shí),存在一定的重合,從而產(chǎn)生直通現(xiàn)象; CONFIDEN

12、TIAL16Power for the Better自驅(qū)驅(qū)動(dòng)波形和原邊主管Vds波形高度耦合,易受其影響; 電源輸出并聯(lián)導(dǎo)致可能的起機(jī)時(shí)預(yù)偏置電壓跌落;MOSFET自身的可靠性問題(抗重復(fù)雪崩擊穿能力和耐dv/dt 耐受力Contents同步整流技術(shù)概述典型電路及其特點(diǎn)損耗分析 CONFIDENTIAL17Power for the Better同步整流電路中常見問題MOSFET 選型設(shè)計(jì)參考1875V100uC31n C1P1 S1TX1100u C24uL12R13675VVOUT=5V&12VACF power stageQ61Q62L23T 7Q64Q65C47Q66Q67C4

13、8FB/HB 200W-800W for Data communicationinputoutputpartdescriptionremark3675V 12v AON6292AON62906m /100V 4.6m / 100V 原副邊匝比:5:2(穩(wěn)壓6: 2(半穩(wěn)壓4060V10vAON6242AON62603.6m/60V 2.4m/60V原副邊匝比:4: 1(穩(wěn)壓10V4060V100u C1P1S1TX 14u L1100u C23675V 12V inputoutputpartdescriptionremark3675V 12v AON6260AON6242 2.4m /60V

14、3.6m / 60V 原副邊匝比:5:2(穩(wěn)壓4060V10vAON67521.7m/30V原副邊匝比:4: 1(穩(wěn)壓同步整流MOS選型考慮outpu Full bridge regulator 200W1000W for 佛如for wireless base stationD13675V100u C24u L1P1S1TX1100u C130VD2inputpartdescriptionremarkT X4Q72L22IRF530Q9P1S1S2TX11m C2I RF530Q4I RF530Q3I RF530Q2I RF530Q12uL11m C1I RF530Q5I RF530Q6I

15、RF530Q7I RF530Q81m C3Buck regulator(33V+ full bridge/push-pull(open loop 200W1000W for wireless base station4u L23675V1m C2P1S1TX 1100u C130V100u C3P1S1 Half bridge /full bridge LLC for54Vout rectifierCONFIDENTIAL22 Power for the Betterinput output part Description remarkAC inputDC input54v AOT2500LAOB2500L6.5m 150V TO-2206.2m 150V TO-263Q6C4C3L1C8D3C2D2Q1Q3T1C1L3Q5D1C5Half bridge /full bridge LLC for 12Vout server powerEfficiency in half load reach the standards is difficulty pointCONFIDENTIAL23Power for the BetterQ4Q2inputoutputpartDescriptionremark