A New Unity Power Factor Telecom Rectifier System by an Active Waveshaping Technique

Transcription

1 A ew Unity Pwer Factr Telecm Rectifier Sytem by an Active Wavehaing Technique Sewan Chi and Yungang Bae Seul atinal Univerity f Technlgy Det. f Cntrl and ntrumentatin Eng. 172 Kngneung-Dng, wn-ku, Seul , Krea chi@nut.ac.kr Abtract Thi aer re a new three-hae telecm rectifier ytem in which inuidal inut current at unity wer factr i achieved. nherent natural wave-haing caability f the lyhae tranfrmer tgether with an active current wavehaing technique reult in a ignificant reductin f inut and utut filter requirement aciated with witching rile and EM. Further, the red cheme i hwn t have higher efficiency becaue it de nt emly an intermediate dc-dc cnverin tage and ha a relatively mall number f witche and dide. The red cheme ha a regulated and ilated utut vltage at lw level that the cheme i uitable fr telecm rectifier. The eratin rincile i decribed alng with a deign examle and a cmarative evaluatin. Exerimental reult n a 1.5kW rttye are rvided t validate the red cncet. Keywrd- telecm rectifier, wavehaing, three-hae wer factr crrectin, lyhae tranfrmer. TRODUCTO n lat decade telecmmunicatin and data cmmunicatin equiment have increaingly been ued. t i required that a frnt end dide rectifier be highly efficient and have high wer denity and lw ct. Due t inherent nnlinear witching dide rectifier uffer frm large cntent f inut current harmnic reulting in many eriu rblem in wer ytem. There have been many arache t eliminate the harmnic in the telecmmunicatin rectifier ytem. A ix-witch PWM rectifier demntrate high inut wer factr, but require cmlicated meaurement and feedback cntrl and i in general ctly [1]. A ingle-witch threehae PFC i imle in cntrl and lw in ct, but uffer frm high witch current rating and high EM due t dicntinuu mde eratin [2] and therefre can nt be alied t higher wer than 10KW. A three-hae rectifier emlying three ingle-hae bt PFC circuit with direct culing erate in the cntinuu cnductin mde(ccm) and therefre allw high wer factr and mall EM filter [3]. Hwever, the utut vltage i high due t bt eratin and require the ue f a fllwing DC-DC cnverter tage t get a lw vltage uch a 48DC in the telecmmunicatin ytem. Recently, an 18-ule ilated rectifier ha been red t rvide a regulated dc vltage at lw level fr telecmmunicatin equiment [4]. Thi cheme i attractive in that natural wer factr crrectin i achieved by a lyhae auttranfrmer, and cntrl i imle ince current balancing can be btained by cnnectin f ecndary winding f high frequency tranfrmer. Hwever, the cheme ha a relatively large number f cmnent and may nt meet the EEE519 current ditrtin limit fr a cae f having lw hrt circuit current t demand lad current rati. n thi aer, a three-hae telecm rectifier baed n arrangement f a lyhae auttranfrmer and an active wave-haing technique i red a hwn in Fig. 1. The red arach incrrate a 12-ule auttranfrmer Fig. 1 Pred telecm rectifier ytem AS /05/$ EEE

2 and tw three-hae dide rectifier, each fllwed by a full bridge cnverter erating at cntinuu cnductin mde. An active wave haing technique i alied t the red cheme reulting in inuidal inut current at unity wer factr. The advantage f the red cheme are; v ab v bc v ca Sinuidal inut current at unity wer factr meeting with EEE519 current ditrtin limit. Higher efficiency due t n ue f an intermediate dc-dc cnverin tage and ue f relatively mall number f cmnent. i L1 K Significantly reduced inut and utut filter requirement aciated with witching rile and EM due t the red active wave-haing technique baed n the lyhae tranfrmer arrangement. lated and regulated dc vltage at lw level alicable t telecm equiment. Suitable fr higher wer alicatin due t CCM eratin in the whle range f lad variatin. i L2 S a1 i a1 The eratin rincile i decribed alng with the reference ignal generatin and cntrl methd in the fllwing ectin. S a2. PROPOSED ACTE DODE RECTFER SYSTEM i a2 A. Oerating Princile Fig. 1 hw the baic cnfiguratin f the red rectifier ytem that emly a three-hae auttranfrmer and tw three-hae dide rectifier, each fllwed by a current urce full bridge cnverter. The three-hae auttranfrmer i emlyed t uly tw et f three-hae vltage fr each dide bridge which lead and lag the inut urce vltage by 15, reectively. The KA rating f the auttranfrmer i 0.24P, and thi cniderably reduce the ize and weight cmared t the equivalent -Y tranfrmer which ha a KA rating f P [5]. The erating rincile i illutrated with variu wavef hwn in Fig. 2. The rectifier inut current can be exreed in te f rectifier utut current, which are inductr current, and witching functin f the dide bridge a, i a i P1 i d1 i P2 K K 1.2K i i i a1 b1 c1 S S S a1 b1 c1 i i a2 a2 L1, ib2 Sb2 il2 i c2 S S Frm the auttranfrmer cnnectin, the inut current can be exreed in te f rectifier inut current a [5], c2 (1) i d2 i d Fig. 2 ariu wavef f the red cheme i a i + i ( i i + i i ) (2) a1 a2 0 c2 b2 b1 c1 te f the inductr current and the witching functin a, Then, the hae a inut current can be exreed in AS /05/$ EEE

3 i a { Sa ( Sb1 Sc1) } il1 + { Sa ( Sc2 Sb2) } il2 t can be nted frm equatin (3) that the inut current i determined by the inductr current. f the inductr current i dc, the inut current wuld have 12-ule characteritic due t natural wave-haing caability f the auttranfrmer. w, the inductr current i cntrlled t have a wave hae given in the fllwing, { v (, v (, v ( ) } * K il1 ( Min 2 2LL ab bc ca t (4) * * 30 il 2 ( il1 ( t ) ω (5) L, k Here, K i a cale factr which can be determined by rati between inut line-t-line vltage LL and utut dc vltage. The deired wave hae f the inductr current i rtin f the line-t-line vltage, hwn a a thick line in Fig. 2. Each current urce full bridge cnverter i erated in CCM t hae it inut inductr current a given in equatin (4) and (5). Mdulating the inductr current a uch reult in inuidal inut current at unity wer factr a hwn in Fig. 2. n the mean time the rimary current f the high frequency tranfrmer i determined by the witching functin f the full bridge cnverter a, ip1( 1 t ip2( 2 L2 t (3) S1( il ( ) (6) S ( i ( ) Then the caacitr inut current can be exreed a, id ( id1( + id 2( (7) ( i 1( + i 2( ) A we can ee frm Fig. 2 the large lw rder (6 th ) harmnic Cmnent Auttranfrmer Full- Bridge Cnverter Switch High Frequency Rectifier Dide High Frequency Tranfrmer Table. Cmnent Rating Calculatin 1- winding 2- winding vltage current vltage current Exrein Deign alue (12kW) LL D A(%) eak vltage eak current current eak vltage eak current current rimary eak vltage rimary eak current 3.16A LL tan L, 18.1A 3 2.9kW (24%) 384 L, k 35.45A L, A 98 L, k 283.6A L, A 384 L, k 35.45A turn rati : 8 : 1 Fig. 3 Cntrl blck diagram in the tw dide current add u and de nt aear in current i d, and therefre filter utut caacitance i greatly reduced. The methd f generating reference ignal fr inductr current i hwn in Fig. 3. The nrmalized wave hae reference, i L1, and i L2, are tred in lk-u table and i ynchrnized with a line-t-line vltage by mean f zercr detecting and hae lcked l circuit. The magnitude reference fr inductr current are al btained by a ignal frm utut vltage regulatin. The inut and utut relatinhi n average value f the re rectifier ytem give, AS /05/$ EEE

4 1 2 L, av (8) d, av 2 (1 D) P where erating range f the duty rati i 0.5<D<1. The average rectifier utut vltage d,av becme [5], d av (9), LL Frm equatin (8) and (9) the turn rati f the high frequency tranfrmer can be determined by, P > LL (10) S Al, the average value f the inductr current becme,, (11) L av L, k Frm equatin (8) and (11), the cale factr K can be btained by, K (12) LL B. Deign Examle A a deign examle fr the red dide rectifier ytem the fllwing arameter are aumed: P 12 kw ; LL 220 ; 48 The utut current i given by, P 250A (13) Then, by letting the nminal duty rati be D 0.6 the turn rati can be calculated by equatin (8) - (10), P : S 8 : 1 (14) Table ummarize the exrein fr vltage and current rating f the tranfrmer and witching device. The current rating f the cmnent in the red cheme deend n the duty rati f the witch. The deign value fr a 12kW rectifier ytem hwn a a deign examle are lited crrending t the exrein. C. Cmarative Evaluatin f the Pred Rectifier n thi ectin a cmarative evaluatin f the red cheme and everal ther cheme cncerning efficiencie, cmnent cunt, and realizatin effrt etc. i given. The cheme cnidered fr evaluatin include ingle-witch PFC, ix-witch PWM rectifier, three ingle-hae PFC[3], and 18-ule rectifier[4]. technique inglewitch PFC 6-witch PWM rectifier three ingle-hae PFC[3] 18-ule rectifier[4] red rectifier cnfiguratin ac-dc-dc-dc ac-dc-dc ac-dc-dc-dc ac-dc-dc ac-dc-dc number f frnt-end 1 (0.67) 6 (0.1) 3 (0.18) witche dc-dc 4 (0.24) 4 (0.24) 12 (0.24) 12 (0.12) 8 (0.13) (witch utilizatin) ttal frnt-end witching le dc-dc ttal frnt-end cnductin le dc-dc ttal ttal number f dide (number f FRD) 12 (6) 12 (12) 36 (14) 32 (14) 16 (4) inut filter r hae-hifting tranfrmer Table. Cmarative Evaluatin f Telecm Rectifier inut filter inut filter n hae-hifting tranfrmer (0.2 P ) hae-hifting tranfrmer (0.24 P ) utut filter inductr ye ye ye ye n ening effrt & cntrl cmlexity medium high high lw medium AS /05/$ EEE

5 The aumed erating cnditin fr evaluatin are lited belw. The utility urce i ideal with a zer internal imedance. The cmnent are ideal, unle ecified therwie. The ytem arameter given in equatin (13)-(15) are ued in the calculatin f witch utilizatin and le. The witching frequency i cntant with f w 30kHz. The maximum eak-t-eak rile f the inductr current i 10% f it value. The intermediate dc vltage are 400 fr ingle-witch PFC, ix-witch PWM rectifier and three ingle-hae PFC[3], 260 fr 18-ule rectifier, and 307 fr the red cheme, reectively. The calculatin f witch utilizatin, and nrmalized witching and cnductin le i baed n the equatin btained in the literature [7]. The evaluatin reult i lited in Table. The red cheme emly a lw ka(0.24p ) lyhae auttranfrmer fllwed by dide bridge a a frnt-end, reulting in natural wavehaing characteritic imilar t the 18-ule rectifier. Since it de nt ue witche erating at high frequency in the frnt-end cnverin tage, the ue f inut filter i nt neceary and requirement f uing EM filter i reduced. Due t cntinuu cnductin eratin in the dc-dc cnverter the required EM filter ize i further reduced. The 18-ule rectifier, which ha al ignificantly reduced EM filter ize, may need t ue a mall inut filter t meet the EEE 519 harmnic tandard. The red cheme hw a lw witch utilizatin in the dc-dc cnverin tage. The ttal number f witche and dide f the red cheme i fairly lw, and eecially the number f fat recvery dide i lwet, reulting in lwer wer le and ct. The witching l f the red cheme i arximately half f that f the 18-ule rectifier while the cnductin l f the red cheme i arximately duble f that f the 18-ule rectifier. Thi i becaue the dc-dc cnverter emlyed in the red cheme i a current-fed tye with the duty cycle ranging between 0.5 and 1 while that f the 18- ule rectifier i a vltage tye with the duty cycle raging between 0 and 0.5. Amng the five cheme cmared, the red cheme i hwn t have the highet efficiency due t the fllwing rean: (1) The ttal wer witch le f the red cheme i hwn t be the mallet, (2) an intermediate dc-dc cnverin tage i nt emlyed in the red cheme, (3) the ttal number f witche and dide i relatively lw.. EXPERMETAL RESULTS A labratry rttye ha been built and the exerimental reult are rvided. The exerimental wavef fr the red cheme are hwn in Fig.4. The ytem arameter fr the exeriment are a fllw: P : 1.5kW Suly : 220(line-t-line, RMS), 60Hz : 48DC (a) nductr current i L1 (b) Rectifier inut current i a1 (c) nut current i a (d) FFT f i a Fig. 4 Exerimental wavef Dc link caacitr C 3300uF, nductr L 1, L 2 5mH. Fig. 4(a) hw the inductr current i L1 whe wavefrm i AS /05/$ EEE

6 haed by the full bridge cnverter. The rectifier inut current i a1, hwn in Fig. 4(b), ha 120 f dicntinuu erid. Thi reult in near inuidal inut current, a hwn cincident in Fig. 4(c). The meaured THD f the inut current i 2.7%. Baed n thee reult, the exerimental reult agree with the analyi hwn in Fig. 2 very well. The validity f the cntrl methd i verified.. COCLUTOS n thi aer a new telecm rectifier ytem i red t draw inuidal inut current at unity wer factr that the red cheme meet with EEE519 current ditrtin limit fr lad with any hrt circuit current t lad current rati. Baed n natural wave-haing caability f the auttranfrmer with lw ka rating(0.24p ) the red active wave haing technique ignificantly reduce inut and utut filter requirement aciated with witching rile and EM. The red cheme i al hwn t have higher efficiency becaue it de nt emly an intermediate dc-dc cnverin tage and ha a relatively mall number f cmnent. The red cheme ha a regulated and ilated utut vltage at lw level and therefre i uitable fr telecm rectifier. Exerimental reult n a 1.5kW rttye have been rvided t validate the red cncet. REFERECES [1] S. Ohtu and S. Muryama, K. Yamamt, A cmact, High - Efficiency and High-Pwer-Factr Rectifier fr Telecmmunicatin Sytem EEE APEC Cnf. l. 2, March [2] M. Ratgi, R. aik, and. Mhan, A Cmarative Evaluatin f Harmnic Reductin Technique in Three-Phae Utility nterface f Pwer Electrnic Lad, EEE Tran. n A, l. 30,. 5, , Se./Oct [3] G. Siazzi and F.C. Lee, mlementatin f Single-Phae Bt Pwer Factr Crrectin Circuit in Three-Phae Alicatin, EEE Tran. n ndutrial Electrnic, l. 44, Jun [4] F.J.M.,Seixa and Barbi,. A 12kW Three- Phae Lw THD Rectifier with High-Frequency latin and Regulated DC Outut, EEE Tran. n Pwer Electrnic, l. 19, March [5] S. Chi, P. Enjeti and. Pitel, Plyhae Tranfrmer Arrangement with Reduced ka Caacitie fr Harmnic Current Reductin in Rectifier-Tye Utility nterface, EEE Tran. n PE, l. 11,. 5, , Set [6] S. Chi, P. Enjeti, H. Lee and. Pitel, A ew Active nterhae Reactr fr 12-Pule Rectifier Prvide Clean Pwer Utility nterface, EEE Tran. n ndutry Alicatin, l. 21,. 6, v./dec [7] W. Klar, and H. Ertl, Statu f the Technique f Three-Phae Rectifier Sytem with Lw Effect n the Main, in Prc. 21t TELEC, June 1999, PP AS /05/$ EEE