?????????????????????????/????????????????????????
?? ????????????????????????(AC/DC??DC/DC)??????????(PWM) ??????“?????????(FOT)”??“????????(COT)”??????????????????????(???磬??????CCM???е????DCM????????????????) ????????????????????????????????????磬????????????????????裩????????????????????????????·??????????????(?????????????????)????????????????????????(GD)?й?????о?????????????/???????????? ??? ?????????FOT??????????????????????????????????????????(TOFF)?????????????????????????(TON)?????????????????????????????COT??????????????????????????????????????????????????????????????????????????FOT??COT??·??????????(FSW)?????仯????????????????????????????(CCM ??DCM??)?й???????????????????????????????????????????Ч?????????????????(?????????EMI?????)?????????????????????????????????ж??м???????????????? ???磬??FOT????????CCM PFC??????????????????????????????????????????????????仯[1]?????????????????????????????????????(TOFF Kt Vin, pk sinθ), ???1??????????????CCM???????????????????[2]?????1????????
?1?????????FOT????PFC????????(??); FSW????????(??) COT????????????????[3-5]?????[6]?????DC/DC????????????????[3]?????????CCM??????????Ч?(???磬?????????????????????)?????????????????????????????????????????????????????????[4]-[5]???????????????????????????????????????????????????????????????????COT ????????[6]??FOT????????[7]??????????????????ν????????仯??????С??[2-7]????????????????????????????????(????CCM?????????????????????)?????????????????????(???磬???????????????????/????????????)?? ??????????????????????????????????????·??????????????????(???????)??????????????????????????????????ú????????? ??????????: ??????? ? 2 ???????????????????(???????FOT???????????????COT??????)??????Q??????????????????????????END-END-TOFF (END-TON)????????????????????????TOFF(TON)?????IR1??IR2?????????????????????[1]??????????????VTH_RAMP??VRAMP??????????2πfline t ??????? T??θ??= TON??θ??+ TFW??θ??+TR??θ??=TON??θ??+ TOFF??θ???????????? 
?2???????PWM??????(??)??FOT????????????????(??) ???? T(θ) << Rt2 Ct2 << 1/fline??fline???????????? ????Ct2????????????????????????????????????????仯?? ?? FOT?????·????????????????????????????????????? Ct2?????????VTH_RAMP (θ)?? 
?????(1)???VTH_RAMP (θ)???: 
??????????????CR1????????????IR1??????CR1?????????VRAMP (θ)????????? 
??(2)????(3)??????????????????????????????(TOFF???)?? 
?????(4)????1/T(θ)?: 
?????(5)???????????????????????????????????????????????(CCM??DCM)???????????????????? ????????????????????????????????????????????????????????(Q)????????????????????????????????????????? ??????????: ?????????? ???????PSIM ???淨??????????(???磬DC/DC???COT??PFC???FOT??DC/DC?????FOT???????) ??????????2??????????? ?????????????????????????????????????PFC??????????????????鷽??????????????????????? ?3??4???????鲨?κ?????[2]??LM-FOT????????400W PFC [8]?????????????????????? ?????????3????????????????????(230Vac-???115Vac-??)??Χ?????и?????????(CCM-??, DCM - ??)???????????LM-FOT?????????????????????????????????????????????????DCM?????????????????4????? 
? 3???????????????鲨?Σ?230Vac ????(??)??115Vac????(??) 
?4???????????: 230Vac????(DCM??????) ???????δ???о? ??????????????????FOT/COT?????????????????????PWM????????????????????鷽?????????????䶮?????У?????????????????????????????????????????????????????????????(???磬Ct2 ??????????)??????????????С???????????????????????????????? ?ο????? [1] C. Adragna, "Fixed-Off-Time Control of PFC Pre-regulators", 10th European Conference on Power Electronics and Applications, EPE 2003, Toulouse, France, paper 382. [2] C. Adragna, S. De Simone and G. Gattavari, "New Fixed-Off-Time PWM modulator provides constant frequency operation in boost PFC pre-regulators", International Symposium on Power Electronics, Electrical Drives, Automation and Motion, SPEEDAM 2008, pp. 656-661. [3] H.C.Lin, B.C Fung and T.Y Chang, "A Current Mode Adaptive On-Time Control Scheme for Fast Transient DC-DC Converters", International Symposium on Circuits and Systems, ISCS 2008, pp. 2602 - 2605. [4] L.F.Shi and L.Y.Xu, "Frequency compensation circuit for adaptive on-time control buck regulator" IET Power Electron, 2014, Vol. 7, Iss.7, pp. 1805–1809. [5] W.C.Chen, H.C.Chen, M.W.Chien, Y.W.Chou, K.H.Chen, Y.H. Lin, T.Y Tsai, S.R Lin, and C.C.Lee “Pseudo-Constant Switching Frequency in On-Time Controlled Buck Converter with Predicting Correction Techniques”, IEEE Transactions on Power Electronics, Vol. 31, Iss.5, pp. 3650 – 3662, May 2016. [6] X. Xu, X. Wu and X. Yan, "A Quasi Fixed Frequency Constant On-Time Controlled Boost Converter", International Symposium on Circuits and Systems, ISCS 2008, pp. 2206-2209. [7] M.C.Lee, X. Jing and P.K.T.Mok, "A 14V-Output Adaptive-Off-Time Boost Converter with Quasi-Fixed-Frequency in Full Loading Range", International Symposium of Circuits and Systems, ISCAS 2011, pp. 233-236. [8] "400 W FOT-controlled PFC pre-regulator with the L6563", STMicroelectronics Application Note, AN2485. ??????? ????????????С???????????????????????? ??????(ST)???????32λMCU?????????????????????????????豸?????????? ??????(ST)????????????????MOSFET?????????????????????????????????????? 
????admin ?????????2019-01-03
