Three-Level TAIPEI Rectifier

Transcription

1 Three-Level TAIPEI Recifier Yungaek Jang, Milan M. Jovanović, and Juan M. Ruiz Power Elecronics Laboraory Dela Producs Corporaion 5101 Davis Drive, Research Triangle Park, C, USA Absrac A new low-cos, hree-phase, four-swich, hree-level, zero-volage-swiching (ZVS), disconinuous-curren-mode (DCM), power-facor-correcion (PFC) boos recifier, for shor named he hree-level TAIPEI recifier, ha achieves a low inpu-curren oal-harmonic-disorion (THD) and feaures ZVS of all he swiches is inroduced. In he proposed recifier, he volage sress of he four swiches is equal o one-half of he oupu volage. Consequenly, he recifier can uilize swiches wih a lower volage raing, which, generally, have lower conducion losses. The performance was evaluaed on a hreephase 6-kW prooype for he line-o-line volage range from 340 V o 50 V. The proposed recifier exhibis efficiency in he 96-98% range, achieves less han 5% inpu-curren THD over he enire inpu and above 10% load range. I. ITRODUCTIO Achieving high efficiency in high-volage applicaions is a major design challenge ha requires he opimizaion of conducion and swiching losses hrough a careful selecion of he converer opology and swiching device characerisics. amely, higher volage-raed semiconducor swiches such as MOSFETs and IGBT swiching devices exhibi larger conducion losses compared o heir counerpars wih a lower volage raing. Generally, swiching losses can be reduced and even eliminaed by resoring o a variey of resonan or sofswiching opologies [1]-[3]. However, he approaches for reducing he conducion losses are limied. An approach ha can furher decrease he conducion losses is o employ a opology ha can uilize swiches wih a lower volage raing and, consequenly, a lower conducion loss. Since in he class of circuis known as mulilevel converers [4]-[6] swiches operae wih a volage sress ha is much less han he inpu and oupu volage, he mulilevel converers are a naural choice in high-volage applicaions. Recenly, a low-cos, hree-phase, wo-swich, zerovolage-swiching (ZVS), disconinuous-curren-mode (DCM), power-facor-correcion (PFC) boos recifier, for shor named he TAIPEI recifier, ha achieves a low inpucurren oal-harmonic-disorion (THD) and feaures ZVS of all he swiches wihou any addiional sof-swiching circuiry was inroduced [7]. When operaing in he line-oline volage range from 180 V o 60 V where 650-V MOSFETs can be used for he wo swiches, his minimumcomponen recifier exhibis excellen performance wih he inpu-curren THD below 5% and efficiency in he 96-97% range, as repored in [8]. However, since he volage sress of he swiches is equal o he oupu volage, he recifier canno mainain his efficiency when he inpu volage is exended above 60 V. amely, for recifiers operaing in he hreephase V L-L, RMS inpu range, he oupu volage is ypically around 800 V. As a resul, he wo-swich, ZVS, DCM, PFC boos recifier operaing in his volage range requires swiches wih a volage raing of a leas 1000 V, which are currenly much less efficien han 650-V raed MOSFETs. In his paper, he concep employed o achieve PFC and ZVS of he swiches in hree-phase, wo-swich, ZVS, DCM, PFC boos recifier is exended o obain a low-cos, hreelevel recifier ha can uilize swiches wih a lower volage raing. In his hree-level recifier, which employs only four swiches, he volage sress across all he swiches is clamped o one half of he oupu volage. When designed for he lineo-line volage range from 340 V o 50 V, he proposed recifier exhibis efficiency in he 97-98% range, achieves less han 5% inpu-curren THD over he enire inpu and above 10% load range, and feaures ZVS of all he swiches. Moreover, he proposed recifier has auomaic volage balancing across he wo oupu capaciors conneced in series wih each capacior having less han 400 V. As a resul, downsream isolaed converers implemened wih 600-Vraed swiches can be conneced across he capaciors wihou creaing a volage imbalance. In addiion, he common-mode elecro-magneic inerference (EMI) of he proposed recifier is low. The evaluaion was performed on a hree-phase 6-kW prooype operaing from he line volage range of V L-L, RMS. II. THREE-PHASE THREE-LEVEL TAIPEI RECTIFIER Figure 1 shows he proposed hree-phase hree-level ZVS PFC DCM boos recifier. The inpu of he circui consiss of hree boos inducors, L, and L 3 coupled o hree capaciors C 1, C, and C 3 conneced in he Y ( sar ) configuraion and he hree-phase inpu erminals hrough an EMI filer (no shown in Fig. 1). The common poin of he capaciors is conneced o he mid-poin beween serially- V A D 1 D D 3 V L B 0 C R C C V L C 3 C 1 C C 3 D 4 D 5 D 6 S D C1 L C D C C O1 R Fig. 1. Proposed hree-phase hree-level ZVS PFC DCM boos recifier. R PR C O /14/$ IEEE 943

2 conneced swich pairs - S and - and also o he midpoin of spli oupu capaciors C O1 and C O. The mid-poin of serially-conneced swiches - S is conneced o oupu capacior C O1 hrough clamping diode D C1 so ha he volage across swich S is clamped o he volage across capacior C O1, which is one half of oupu volage. Similarly, he mid-poin of serially-conneced swiches - is conneced o oupu capacior C O hrough clamping diode D C and he volage across swich is also clamped o one-half of oupu volage. Clamping capacior C C is conneced beween he mid-poins of he wo pairs of serially-conneced swiches and i is pre-charged o is seady-sae average volage of one-half of he oupu volage hrough he loop consising of capacior C O, he body diode of swich S, precharge resisor R PR, and a winding of coupled inducor L C. Capacior C R ha is used o rese he inducor currens is conneced across he serially-conneced pairs of swiches and is decoupled from he oupu by coupled inducor L C. Is average volage is equal o he oupu volage since he average volage across he windings of L C is zero. The volages across swiches and are clamped o he difference of he volages across capacior C R and C C hrough he body diodes of swich and swich, respecively. Since his difference is equal o one-half of he oupu volage, he volages across all four swiches in he circui in Fig. 1 are clamped o one-half of he oupu volage. Generally, any kind of swich ha is capable of S S S Fig.. DTs O O DTs O O O O Ts d Ts Ts d d DTs O (c) Gaing waveforms of swiches : frequency conrol; pulse-widh-modulaion (PWM); (c) phase-shif PWM. O DTs O O O O conducing curren in boh direcions and blocking volage in one direcion such as for example a MOSFET or an IGBT wih an aniparallel diode is suiable for his applicaion. To achieve a low inpu-curren THD, high PF, and a wide-load-range sof-swiching of he swiches, he circui in Fig. 1 mus operae in DCM wih a low-bandwidh oupuvolage conrol. This conrol can be implemened in a variey of ways. Figure shows iming waveforms of he four swiches of he circui in Fig. 1 for variable swichingfrequency conrol. In he variable-frequency conrol in Fig., wo pairs of swiches -S and - are swiched in a complemenary fashion wih a small dead ime d beween heir commuaion insans o enable he pair of swiches ha is abou o urn on o achieve ZVS. Since dead ime d is very small in comparison wih swiching period T S, he effec of he dead ime is negligible, i.e., i can be assumed ha he duy cycle of each swich is approximaely 50%. Because he swiches of each pair operae wih he same gae signal as shown in Fig., he conrol circui is idenical o ha of he wo-level wo-swich, ZVS, DCM, PFC boos recifier [8]. Figure shows anoher conrol mehod of he circui in Fig. 1. In his conrol, swiches and are swiched a a consan frequency in a complemenary fashion wih a small dead ime, i.e., wih approximaely 50% duy raio. The duy raio of swiches S and, whose urn-on insans are synchronized wih he urn on insans of and, respecively, is pulse-widh modulaed o provide regulaion of he oupu. While he recifier oupu volage can be fully regulaed by his consan-frequency pulse-widh modulaion (PWM) conrol, he recifier exhibis high inpu-curren THD and loses ZVS when he duy cycle becomes small. However, by properly combining variable swichingfrequency and PWM conrol, low THD and a wide ZVS range can be achieved wih a reduced frequency range. amely, since in he oupu-volage-regulaed converer in Fig. 1 he swiching frequency increases as he load decrease, he frequency range can be reduced by employing variable swiching-frequency conrol over he range from full load o ligh load and resoring o consan-frequency conrol a ligh loads. Figure (c) shows a phase-shif conrol mehod of he circui in Fig. 1. Two pairs of swiches - and S - are swiched a a consan frequency in a complemenary fashion wih a fixed duy raio of approximaely 50%. The conrol is achieved by a phase shif of he swiching insans of he - pair wih respec o he corresponding swiching insans of he S - pair. In his phase-shif conrol, he oupu volage is zero when he phase shif is zero and is maximum when phase shif is 180 0, i.e., T S /. Similarly, combining variable swiching-frequency conrol and phase-shif conrol provides low THD and a wide ZVS range as well as a narrow swiching frequency range over he enire load and inpu range. I should also be noiced ha coupled inducor L C plays a major role in aenuaing he oupu common-mode noise. Moreover, because of he presence of coupled inducor L C, a parallel operaion of recifiers is also possible. 944

3 III. AALYSIS OF OPERATIO Figure 3 shows a simplified model of he circui in Fig. 1 along wih reference direcions of currens and volages. To simplify he analysis of operaion, i is assumed ha ripple volages of he inpu and oupu filer capaciors shown in Fig. 1 are negligible so ha he volage across he inpu and oupu filer capaciors can be represened by consan-volage source, V B, V C, 1, and. Also, i is assumed ha in he on sae, semiconducors exhibi zero resisance, i.e., hey are shor circuis. However, he oupu capaciances of he swiches are no negleced in his analysis. Coupled inducor L C in Fig. 1 is modeled as a wo-winding ideal ransformer wih magneizing inducance L M and leakage inducances L LK1 and L LK. I should be noed ha he average volage across flying capacior C R is equal o oupu volage = 1 and he average volage across clamping capacior C C is equal o one half of oupu volage. The circui diagram of he simplified recifier is shown in Fig. 3. The reference direcions of currens and volages in Fig. 3 correspond o he 60-degree segmens of a line cycle when > 0, V B < 0, and V C < 0. To furher faciliae he explanaion of he operaion, Fig. 4 shows opological sages of he circui in Fig. 3 during a swiching cycle, whereas Fig. 5 shows he power-sage key waveforms. As can be seen from he gae-drive iming diagrams of swiches - in Fig. 5, he conrol used in his explanaion is a combinaion of variable-frequency conrol and phase-shif conrol. In Fig. 5, swiches and and swiches S and operae in a complimenary fashion wih a shor dead ime beween heir commuaion insans, i.e., wih a fixed duy raio of approximaely 50%. This gaing sraegy enable ZVS of he swiches ha are abou o urn on. The oupu-volage regulaion is primarily done by frequency conrol, excep a ligh loads and/or high inpu volages where phase-shif conrol is used. As shown in Figs. 4 and 5, before swich S is urned off a =T 1, inducor curren flows hrough swiches and S. The slope of inducor curren is equal o / and he peak of he inducor curren a =T 1 is approximaely V C V B L D 1 D 5 L 3 D 6 i S C R S i S3 i S4 Fig. 3. Simplified circui diagram of proposed hree-phase boos power sage showing reference direcions of currens and volages. The model is valid for segmen where > 0 and V B < V C < 0. i M 1 C C L M D C1 D C i DC L LK1 1 L LK VA I L1(PK) = DTS, (1) L1 where is he line-o-neural volage and T S is he swiching period. Because he dead ime beween urn-off of swich and urn-on of swich is very small in comparison wih swiching period T S, he effec of he dead ime is negleced in Eq. (1). During he ime period beween T 0 and T 1, curren decreases a a rae of -1 /(L M L LK1 ) while curren increases a a rae of ( -1 )/(L M L LK ). Magneizing curren i M is he difference beween currens and. I should be noed ha he magneizing inducance value of coupled inducor L M is designed o be sufficienly large so ha he ripple curren of he coupled inducor does no significanly affec recifier operaion. As shown in Fig. 1, he wo windings of inducor L C are coupled in such a way as o cancel he magneic fluxes from he differenial curren of he wo windings so ha he large magneizing inducance can be obained by a small gap in he core wihou sauraion. Since he effec of he curren ripple of currens and is negligible, hey are no furher discussed, alhough hey are shown in he opological sages in Fig. 4. A =T 1, when swich S is urned off, inducor curren sars charging he oupu capaciance of swich S, as shown in Fig. 4. Because he sum of he volages across swich S and swich is clamped o clamping capacior volage, he oupu capaciance of swich discharges a he same rae as he charging rae of he oupu capaciance of swich S. This period ends when he oupu capaciance of swich S is fully charged and clamping diode D C1 sars o conduc a =T, as shown in Fig. 4(c) and Fig. 5. Afer =T, swich is urned on wih ZVS. Because clamping diode D C1 is forward biased, inducor curren begins o linearly decrease. The slope of inducor curren is equal o ( -1 )/ and he inducor curren a =T 3 is approximaely VA ( 1 D) VO1 = T3 = TS, () L1 A =T 3, when swich is urned off, inducor curren sars charging he oupu capaciance of swich, as shown in Fig. 4(d). Because he sum of he volages across swich and swich is clamped o he volage difference beween flying capacior volage and clamping capacior volage, he oupu capaciance of swich discharges a he same rae as he charging rae of he oupu capaciance of swich. This period ends when he oupu capaciance of swich is fully discharged and he ani-parallel body diode of swich sars o conduc a =T 4, as shown in Fig. 4(e) and Fig. 5. A =T 5, swich is urned on wih ZVS and inducor curren is commuaed from he aniparallel body diode of swich o he swich, as illusraed in Fig. 4(f). Because he body diode of swich is forward biased and swich is on, inducor currens and begin o linearly increase afer =T 4. A =T 5, swich is urned on wih ZVS and inducor currens and are commuaed from he aniparallel body diode of swich o he swich, as illusraed in Fig. 4(f). This period ends when inducor 945

4 1 1 1 V C V B V C V B V C V B [T 0-T 1] [T 1-T ] (c) [T -T 3] V C V B V C V B V C V B (d) [T3-T4] (e) [T4-T5] (f) [T5-T6] V C V B V C V B V C V B (g) [T6-T7] (h) [T7-T8] (i) [T8-T9] V C V B V C V B V C V B (j) [T9-T10] (k) [T10-T11] (l) [T11-T1] 1 1 V C V B V C V B (m) [T 1-T 13] (n) [T 13-T 14] Fig. 4. Topological sages of proposed recifier when > 0, V B < 0, and V C < 0. curren decreases o zero a =T 6. To mainain DCM operaion, minimum volage (MI) across flying capacior C R, which is equal o oupu volage, is VA(PK) VCR(MI) = = VL L, RMS (3) 1 D 3 1 D ( ) where -PK is he peak line-o-neural volage. I also should be noed ha because during he T 4 -T 6 inerval inducor currens and flow in he opposie direcion from inducor curren, he average curren hrough swiches and is reduced so ha he swiches in he proposed recifier exhibi reduced power losses. 946

5 T S S 1 O O O O S V S1 V S V LC i S S O O S O O - -V B L - - DT S -V B L During he ime period beween =T 6 and =T 7, inducor currens and coninue o flow hrough swiches and, as illusraed in Fig. 4(g). As shown in Fig. 5, he slopes of inducor currens and during his period are equal o -V B /L and -V C /L 3, respecively. The peaks of he inducor currens a he momen when swich urns off a =T 7 are approximaely VB I L(PK) = DTS and (4) L -V C L 3 -V C / -V B / L 3 L ZVS ZVS -V B L - / - - / V - B L - / i Dc1 Fig. 5. Key waveforms of proposed recifier when > 0, V B < 0, and V C < 0. VC I L3(PK) = DTS. (5) L3 As i can be seen in Eqs. (1), (4), and (5), he peak of each inducor curren is proporional o is corresponding inpu volage as long as duy cycle D and swiching period T S are consan during one half of he line cycle. Afer swich is urned off a =T 7, inducor currens and sar o simulaneously charge he oupu capaciance of swich and discharge he oupu capaciance of swich S, as shown in Fig. 4(h). This period ends a =T 8 when he oupu capaciance of swich is fully charged and clamping diode D C sars o conduc a =T 8, as shown in Fig. 4(i) and Fig. 5. Afer =T 8, swich S is urned on wih ZVS. Because clamping diode D C is forward biased, inducor currens and begin o linearly increase. This period ends when inducor curren reaches zero a =T 9. The slopes of inducor currens and are equal o (-V B )/L and (-V C )/L 3, respecively. Inducor curren a =T 10 when swich urns off is approximaely VB ( 1 D) VO = T10 = TS. (6) L A =T 10, when swich is urned off, inducor curren sars charging he oupu capaciance of swich, as shown in Fig. 4(k). Because he sum of he volages across swich and swich is clamped o he volage difference beween flying capacior volage and clamping capacior volage, he oupu capaciance of swich discharges a he same rae as he charging rae of he oupu capaciance of swich. This period ends when he oupu capaciance of swich is fully discharged and he ani-parallel body diode of swich sars o conduc a =T 11, as shown in Fig. 4(l) and Fig. 5. A =T 1, swich is urned on wih ZVS and inducor currens is commuaed from he aniparallel body diode of swich o he swich, as illusraed in Fig. 4(m). Because swiches and S are on, inducor curren begins o linearly increase afer =T 11. During period T 1 -T 13, increasing inducor curren coninues o flow hrough swiches and S, as shown in Fig. 4(m). Finally, afer inducor curren reaches zero a =T 13, a new swiching cycle begins, as shown in Fig. 4(n). Since in he circui shown in Fig. 1 he charging curren of each boos inducor during he ime when he relaed swich is on is proporional o is corresponding phase volage and is discharging curren proporional o he difference of flying capacior volage and he corresponding phase volage, as shown in he inducorcurren waveforms in Fig. 5, average inducor curren <I L (AVG) > Ts of each boos inducor during a swiching cycle is TS IL(AVG) = Ts 3L ( 4D ) 1 VCR VL, RMS sin ω (1 D) VCR, (7) VCR VL, RMS sin ω where L= =L =L 3, and ω is he angular frequency of he line volage. For maximum duy cycle D MAX =0.5, average inducor curren <I L (AVG) > Ts, D=0.5 of each boos inducor during a swiching cycle is T V V sin ω S CR L, RMS I = L (AVG). (8) Ts, D= 0.5 8L VCR VL, RMS sin ω By defining inpu-o-oupu volage conversion raio M as VO M = (9) VL, RMS and recalling ha he volage across flying capacior C R is equal o oupu volage, i.e., =, average inducor curren <I L (AVG) > Ts in Eq. (7) can be rewrien as 947

6 ( 4D ) IL (AVG) V OTS 1 sin ω (1 D) M = 3L, (10) Ts M sin ω i.e., for D MAX =0.5, IL (AVG) VOTS sin ω = Ts, D = 0.5 8L M sin ω. (11) The curren disorion of he average inducor curren in Eq. (11) is brough abou by he denominaor erm (M sinω) and i is dependen on volage-conversion raio M. I should be noed ha he curren disorion of he average inducor curren is also dependen on duy cycle D if duy cycle D is less han 0.5 as shown in Eq. (10). <I L > Ts [A] <I L > Ts [A] <I L > Ts [A] M =.8 M =. M =.6 M = L=89 μh, =780 V, f L =50 Hz, P O =6 kw M =.8 M =.4 Time [second] L=89 μh, =780 V, f L =50 Hz, P O =6 kw M =.8 M =. M =. M =.6 M =.4 Time [second] M =.6 M =.4 M = 1.8 M = L=89 μh, =780 V, f L =50 Hz, P O =6 kw Time [second] D = 0.5 M = 1.8 M = 1.8 D = 0. D = 0.1 M = (c) Fig. 6. Calculaed average boos inducor curren <I L-AVG> Ts for various inpu-o-oupu volage conversion raios M and: D=0.5; D=0.; (c) D=0.1. TABLE I THD and harmonics of average boos inducor currens shown in Fig. 6. M THD D=0.5 D=0. D=0.1 3 rd 5 h -99 h THD 3 rd 5 h -99 h THD 3 rd 5 h -99 h Figure 6 shows calculaed average boos inducor curren <I L-AVG > Ts wih duy cycle D=0.5, D=0., and D=0.1 for various inpu-o-oupu volage conversion raios M. The harmonic conen of he average inducor currens shown in Fig. 6 is summarized in Table I. As can be seen from Table I, he 3 rd harmonic is he dominan disorion componen. However, since in he hree-wire power sysems, he neural wire is no available (or no conneced) he line currens canno conain he riplen harmonics (he 3 rd harmonic and he odd muliples of he 3rd harmonic). As a resul, he proposed circui exhibis a very low THD and high PF since according o Table I he remaining harmonics conribue less han 3% of oal curren disorion up o D=0.. I should be noed ha since he line currens canno conain he hird harmonic, he 3 rd harmonic of he inducor currens flow hrough filer capaciors C 1 -C 3. Finally, i should be noed ha he proposed recifier auomaically balances he volages across he wo oupu capaciors, i.e., no addiional volage-balancing circui is required. aural volage-balancing is achieved because in he circui in Fig. 1 he average volages across serially conneced swich pairs -S and - are equal o average volages 1 and across capaciors C O1 and C O, respecively, since he average volages across he windings of inducor L C are zero. The swich pairs are operaed symmerically and heir average volages are equal o / so ha 1 = = /. IV. EXPERIMETAL RESULTS The performance of he proposed recifier was evaluaed on a 6-kW prooype circui ha was designed o provide an 800-V oupu from a hree-phase V L-L, RMS inpu ha covers he sandard inpu range of V L-L, RMS wih 10% margin. Figure 7 shows he power-sage schemaics of he experimenal prooype circui along wih componen informaion. Figures 8 and show he measured inpu-curren waveforms of he experimenal circui operaing a full power from 340 V L-L, RMS and 50 V L-L, RMS inpu, respecively. The measured THDs of he inpu curren are approximaely 0.75% and.9% a 340-V L-L, RMS and 948

7 L1, L, L3 PQ50/50-3C96 Liz 0.1mmx400 36T, 89 uh V A V B V C C 1 C C 3 D1-D6 C4D010D L L 3 C1-C3.uF /630 V D 1 D D 3 D 4 D 5 D 6 CR 4 x1uf/ 875 V C R S S1 - S4 IPW65R041CFD 1.nF /1kV 1.nF /1kV 1uF /875 V C C 1.nF /1kV 1.nF /1kV Lc : ETD59-3C96 Liz 0.1mmx00, 55T:55T Lm=1. mh, Llk=347uH Fig. 7. Experimenal prooype circui of proposed recifier. D C1 L C D C 4x470uF /450 V C O1 C O 4x470uF /450 V Dc1, Dc RHRP1560 i La i Lb i Lc i La 5 μsec/div i La i Lb i Lc V I =340 V L-L, =789 V, P O =5.9 kw, f S =40 khz μsec/div i La i A i B i C i A 5 msec/div i C 5 msec/div i A i B THD A =0.75% THD B =0.7% THD C =0.68% V I =340 V L-L, =789 V, P O =5.9 kw f S =40 khz, η=96.4%, PF= i A THD A =.90% i Lb i Lc i Lb V I =50 V L-L, =83 V, P O =5.9 kw, f S =87 khz Fig. 9. Measured waveforms of inducor currens,, and a full power for hree-phase line-o-line RMS inpu volage: 340 V L-L; 50 V L-L. [50 A/div] 5 μsec/div i Lc i B i B THD B =.76% i S [50 A/div] i S i C i C THD C =.58% V I =50 V L-L, =83 V, P O =5.9 kw f S =87 khz, η=98.%, PF= Fig. 8. Measured inpu-curren waveforms a full power for hree-phase line-o-line RMS inpu volage: 340 V L-L; 50 V L-L. Time scale is 5 ms/div. [10 A/div] V I =340 V L-L, =789 V, P O =5.9 kw, f S =40 khz μsec/div 50-V L-L, RMS, respecively. Figure 9 shows he measured curren waveforms of boos inducors, L, and L 3 a full power. The measured waveforms and he ideal waveforms in Fig. 5 differ during he ime inervals when he inducor currens are supposed o be zero. This difference is caused by he parasiic resonance of he juncion capaciances of he reverse-biased inpu bridge diodes wih he boos inducors. This ringing curren affecs he THD of he inpu curren. However, even wih hese non-ideal inpu bridge diodes D 1 - D 6, he measured THD was well below 5% over enire inpu volage and load range. By selecing diodes wih smaller juncion capaciances, he qualiy of he inpu currens can be improved furher. i S V I =50 V L-L, =83 V, P O =5.9 kw, f S =87 khz Fig. 10. Measured waveforms of drain currens and i S of swiches and S and curren of clamp diode D C1 a full power for hree-phase line-o-line RMS inpu volage: 340 V L-L; 50 V L-L. Figure 10 shows he full-power waveforms of he drain curren of swiches and S, as well as he waveform of curren ha flows hrough clamp diode D C1. I can be i S 949

8 V S1 V S V S3 V I =340 V L-L, =789 V, P O =5.9 kw, f S =40 khz V S1 V S V S3 and are similar o hose of swiches and S. Figure 11 shows he waveforms of he drain volages of swiches -. I can be seen ha all he swich volages are well clamped o one half of oupu volage. Finally, he measured efficiencies of he proposed recifier as a funcion of he oupu power for 380 V L-L, RMS and 480 V L-L, RMS inpu are ploed in Fig. 1. The measured full-load efficiency a 480 V L-L, RMS is 98.1%, whereas he full-load efficiency a 380 V L-L, RMS is 97.%. V S4 V S1 V S V S3 V S V S1 V S3 V S4 4 μs/div V I =50 V L-L, =83 V, P O =5.9 kw, f S =87 khz V S4 V S4 μs/div Fig. 11. Measured full-power waveforms of swich volages V S1, V S, V S3, and V S4 for hree-phase line-o-line RMS inpu volage: 340 V L-L; 50 V L-L. Efficiency V = 480 V I L-L, RMS V = 380 V I L-L, RMS =800 VDC Oupu Power [kw] Fig. 1. Measured efficiencies of experimenal prooype as funcions of oupu power. V. SUMMARY In his paper, a new hree-phase four-swich hree-level ZVS PFC DCM boos recifier has been inroduced. The volage across all he swiches is clamped o one- half of he oupu volage. The proposed recifier achieves less han 5% inpu-curren THD over he enire inpu range and above 10% load, as well as feaures complee ZVS of he swiches. The performance evaluaion was done on a hree-phase 6-kW prooype operaing in he V L-L, RMS line-volage range. The measured inpu-curren THD a 380 V L_L, RMS and 480 V L_L, RMS were 0.75% and.9%, respecively. The measured full-load efficiency was in he 97-98% range. REFERECES [1] E. H. Ismail and R. W. Erickson, "A Single Transisor Three Phase Resonan Swich for High Qualiy Recificaion," IEEE Power Elecronics Specialiss Conf. (PESC) Record, 199, pp [] S. Gaaric, D. Boroyevich, and F. C. Lee, "Sof-Swiched Single-Swich Three-Phase Recifier wih Power Facor Correcion," IEEE Applied Power Elecronics Conference (APEC) Proc., 1994, pp [3] Y. Jang and M. M. Jovanović, "Design Consideraions and Performance Evaluaion of A 6-kW, Single-Swich, Three-Phase, High-Power- Facor, Muli-Resonan, Zero-Curren-Swiching Buck Recifier, IEEE In l Telecommunicaions Energy Conf. Proc., 1997, pp [4] J. R. Pinheiro and I. Barbi, The hree-level zvs-pwm dc-o-dc converers, IEEE Transacions on Power Elecronics, vol. 8, o. 4, pp , Oc [5] X. Ruan, L. Zhou, and Y. Yan, Sof-swiching pwm hree-level converers, IEEE Trans. Power Elecronics, vol. 16, no. 5, pp. 61 6, 001. [6] P. M. Barbosa, F. Canales, J. M. Burdio, and F. C. Lee, The hree-level converer and is applicaion o power facor correcion, IEEE Transacions on Power Elecronics, vol. 0, o. 6, pp , ov [7] Y. Jang and M. M. Jovanović, The Taipei recifier a new hree-phase wo-swich zvs pfc dcm boos recifier, IEEE Transacions on Power Elecronics, vol. 8, o., pp , Feb [8] Y. Jang, M. M. Jovanović, Y. H. Chang, K. H. Fang, and J. X. Zhu Design Consideraions and Performance Evaluaion of Three-Phase Two-Swich ZVS PFC DCM Boos Recifier (Taipei Recifier) for Telecom Applicaions, Record of he 34h IEEE Inernaional Telecommunicaions Energy Conference, Scosdale, Arizona, Sep Oc. 4, 3-, 01. seen ha he drain currens of swiches and S sar o flow in he negaive direcion, which indicaes ha he body diodes of swiches and S are conducing and he volages across he swiches are zero before gaing. The waveforms of 950