, pp.267-278 hp://dx.doi.org/10.14257/ijca.2014.7.4.23 High Power Full-Bridge DC-DC Converer using a Cener-Tapped Transformer and a Full-Wave Type Recifier Min-Gi Kim, Geun-Yong Park, Doo-HeeYoo and Gang-YoulJeong Deparmen of Elecronic Informaion Engineering, Soonchunhyang Universiy 22 Soonchunhyang-Ro, Shinchang-Myun, san-si, Choongnam, Souh Korea gangyoul@sch.ac.kr bsrac This paper proposes a high power full-bridge DC-Donverer, using a cener-apped ransformer and a full-wave ype recifier. The proposed converer realizes unipolar primary volage swiching, using he unipolar pulse-widh modulaion (PWM) echnique. lso, he proposed converer reduces he freewheeling conducion loss, using he unipolar PWM echnique and a resonan circui, composed of a clamp capacior and resonan inducor in he primary, and hus achieves high efficiency. However, because he proposed converer uses only a full-bridge circui, cener-apped ransformer, and full-wave ype recifier, he srucure of he proposed converer is simple. In his paper, he operaional principle of he proposed converer is described in deail, and a design example of a proposed converer prooype is shown. Finally, experimenal resuls of he prooype are shown, o verify he feasibiliy of he proposed converer. Keywords: Full-bridge DC-Donverer, Cener-apped ransformer, Full-wave ype recifier, unipolar PWM echnique, Resonan circui 1. Inroducion Recenly, according o he increase of power capaciy of elecric/elecronic devices, many high power DC-DC power converers have been proposed [1-15]. mong hese power converers, convenional ZVS (Zero Volage Swiching) unipolar PWM full-bridge converers are a popular opology for medium/high power applicaions, offering desirable feaures, such as ZVS operaion, and high efficiency. However, he convenional ZVS full-bridge DC-Donverer has a serious disadvanage: ha of he narrow ZVS range of he lagging leg. During he lagging leg ransiion under ligh load operaion, he primary curren decreases, and finally changes is polariy; bu he energy available for charging or discharging he swich oupu capacior is insufficien, which unforunaely resuls in hard swiching condiions. However,because his also increases he circulaing curren under normal load, iresuls in increase of he oal conducion loss of he converer and he volage/curren sress of each swich. Therefore, many research resuls have been proposed, o exend he ZVS range down o a ligh load [3-6]. Bu here are some disadvanages: in [3] and [4], he effecive duy raio should be reduced, and in [5] and [6], excessive conducion losses occur,due o an increased auxiliary resonan curren.lso, i causes problems, such as he hermal problem and increased cos. Because of hese problems, ZVS full-bridge DC-Donverers were proposed ha use wo ransformers. Bu, his proposal canno solve he bulky sysem problem. Half- ISSN: 2005-4297 IJC Copyrigh c 2014 SERSC
bridge DC-Donverers wih oher mehods [7-11] are proposed, bu heir oupu power was no large. In his paper, a high power DC-Donverer using a cener-apped ransformer and fullwave ype recifier is presened. clamp capacior and resonan inducance are used as a resonan circui for he sof-swiching of he converer primary, wih he unipolar PWM echnique. The proposed converer reducesfreewheeling conducion loss wih he unipolar PWM echnique, and a simple resonan circui, composed of a clamp capacior and resonan inducor. The proposed converer uilizes he unipolar PWM echnique like he convenional full-bridge DC-Donverer, so is modificaion from he convenional converer circui is easy. Thus, he proposed converer achieves high efficiency. lso,because he proposed converer is composed of only a full-bridge circui, cener-apped ransformer, and full-wave ype recifier, he srucure of he proposed converer becomes simple. In his paper, heoperaional principle is explained in deail, and a design example of a prooype of he proposed converer is shown. Experimenal resuls based on he prooype are shown, o confirm he validiy of he proposed converer. 2. Operaional Principles D S1 C S1 i S2 B D S4 C S4 Figure 1. circui diagram of he proposed converer Figure 1 shows a circui diagram of he proposed full-bridge DC-Donverer. The proposed converer is composed of he primary, he cener-apped ransformer, and he secondary. The primary par of he proposed converer is composed of a Dpu source, he main swiches of he full-bridge circui, a clamp capacior, and a resonan inducor. The secondary par of he proposed converer is composed of a full-wave ype recifier and, oupu filer capacior, and load. The configuraion of he proposed converer is basically similar o ha of he convenional full bridge DC-Donverer, excep for he cener-apped ransformer, and resonan circui, composed of a clamp capacior and resonan inducor. Figure 2 shows he key par waveforms of he proposed converer in seadysae. The proposed converer operaesbased onhe gae-source volages of he main swiches.the converer operaion can be divided ino six modes or hree caegories: power delivery inerval, freewheeling inerval, and commuaion inerval. N s1 N s2 V Dr1 V Dr2 268 Copyrigh c 2014 SERSC
V GS1,3 V GS2,4 V GS1 V GS3 V GS1 V B DT s D e T s DT s Figure 2. The key par waveforms of he proposed converer in seadysae Figure 3 showshe equivalen circuis of each mode of he proposed converer, where he bold lines denoepahs ha conduc currens, andhe doed lines denoe pahs ha do no conduc curren. To illusrae he seady sae operaion, he following appropriae iems are assumed: 1) The power swiches are ideal, excep for heir ani-parallel diodes and parasiic capaciors. 2) The magneizing inducance is of very large value, and and ( ) are he primary and he secondary urn numbers of he ransformer, respecively. 3) The oupu volage is consan. V GS2 V GS4 V GS2 V B - 0 1 Mode 1 Mode 2 T T Mode 3 V Cc,max Mode 4 T s =T/2 Mode 5 2 3 4 5 6 Mode 6 Copyrigh c 2014 SERSC 269
D S1 C S1 DS4 C S4 B D S1 C S1 B D S1 C S1 B V N Dr1 s1 N s2 V Dr2 DS4 C S4 DS4 C S4 (a) Mode 1 (b) Mode 2 (c) Mode 3 N s1 N s2 N s1 N s2 V Dr1 V Dr2 V Dr1 V Dr2 D S1 C S1 DS4 C S4 B N s1 N s2 V Dr1 V Dr2 (d) Mode 4 270 Copyrigh c 2014 SERSC
D S1 C S1 DS4 C S4 D S1 C S1 B B DS4 C S4 Figure 3. The equivalen circuis of each mode of he proposed converer Mode 1( ): In his mode, he power is delivered from he primary o he secondary. This is he power delivery inerval. The secondary diodes and are urned on and off, respecively. his ime, he primary curren increases almos linearly, as follows: Then, he resonan inducor volage and he clamp capacior volage are expressed, respecively, as follows: The slope of he primary curren is changed more rapidly by he clamp capacior volage, compared wih he convenional full-bridge DC-Donverer. (e) Mode 5 (f) Mode 6 N s1 N s2 N s1 N s2 V Dr1 V Dr2 V Dr1 V Dr2 (1) (2) (3) Mode 2( : Mode 2 begins when he swich is urned off a ime. This mode is he freewheeling inerval. The primary curren charges and discharges he parasiic Copyrigh c 2014 SERSC 271
capaciors and of he swiches and, respecively. his ime, he primary curren can be expressed as follows: (4) The ani-parallel diode of swich conducs, and hus he ZVS of is achieved. Mode 3( : Mode 3 begins when he swich is urned off a ime,. During mode 3, he direcion of primary curren is changed, which is differen from modes 1 and 2. The primary curren is expressed by he following equaion: ime, he commuaion beween secondary diode and is compleed, and his mode ends. Since from mode 4, he mode operaions are symmeric in he curren conducing pahs and componens, as shown in Figures 2 and 3, he explanaion of he nex hree modes, modes 4~6, can convenienlybe omied. 3. Design Examples In order o verifyhe performance of he proposed converer, a prooype of he proposed convereris designed and implemened, based on he following Table 1: Table 1. Design specificaions of heprooype converer Iem Symbol Value Inpu DC volage 380V Oupu DC volage Max oupu power Swiching frequency 24V 960W 100kHz Effeciveduy raio 0.5 Based on he srucure and operaion of he proposed converer, he main cener-apped ransformer urn raio (= ) is calculaed by he following equaion: (5) (6) 272 Copyrigh c 2014 SERSC
where, is he effecive duy raio of he converer primary volage applied o he bridge poins -B. Thus, based on he design specificaions of Table 1, he urn raio is se as. modes 1 and 3, he clamp capaciance a mode 3, and he maximum volage clamp capacior from equaion (3), as follows: is calculaed by is maximum volage is calculaed by he ripple volage of he where, is he load curren a maximum oupu power.from equaion (7), he clamp capaciance is given by he following equaion: In order ha he slope of he primary curren becomes posiive, he following relaion should be saisfied: Therefore, he clamp capaciance follows: From equaion (9), he maximum value (7) (8) (9) can be calculaed using equaions (8) and(9), as (10) of he clamp capacior volage should be less han. Here, he design margin of he maximum value is considered, whichis se o abou 10% of hevolage. Therefore, he clamp capaciance was seleced as an approximaed value of =0.33μF. Thus,by equaion (7), he maximumclamp capacior volage is modified o. In order o achieve he ZVS of he primary full-bridge circui,normally he lagging-leg swiches and mus operae as he ZVS a he urn-off condiion. This means ha he following relaion should be saisfied: where, helef side is he energy sored in a mode 1,and he righ side is he double margin value of he energy comingou from he resonan inducor, whichhe parasiic capaciors of he lagging-leg swiches and should charge or discharge.so he peak value of he primary curren can beapproximaely calculaed by he following equaion: (11) Copyrigh c 2014 SERSC 273
(12) where, is he effecive on-duy ime, which can be approximaed as he ime of mode 1.Therefore, he resonan inducance can be calculaed using equaions (11) and(12), as follows: where,he parasiic capaciance of he MOSFET swiches is seleced as =2200pF, according o he specificaion of he MOSFET used, FQ24N50. Thus, he resonan inducance is selecedas. 4. Experimenal Resuls To verify he effeciveness of he proposed converer, a prooype of he proposed converer is implemened, wih he specificaions of Table 1 in Secion 3. Figure 4 shows he experimenal waveforms of he gae-source driving volages of he upper MOSFET swiches and, and he bridge volage of he primary full-bridge MOSFET circui. From his, i can be known ha he conrol and driving circui operaions of he proposed converer are good, and he full-bridge circui is well operaed by he operaions of he conrol and driving circuis. Figure 5 shows he experimenal waveforms of he primary volages and currens of he primary full-bridge circui, which le us know ha he full-bridge circui is well designed and operaed, because he experimenal waveforms coincide wih he heoreical waveforms of Figure 2. Figure 6 shows he experimenal waveforms of he secondary oupu volage, and curren of he proposed converer. This shows ha he proposed converer operaes well and sably, as a high power DC-Donverer. (13) Figure 4. Experimenal waveforms of he gae-source driving volages of he upper swiches, and he bridge volage of he primary full-bridge circui 274 Copyrigh c 2014 SERSC
Figure 5. Experimenal waveforms of he primary volages, and curren of he full-bridge circui Figure 6. Experimenal waveforms of he secondary oupu volage, and curren of he proposed converer 5. Conclusion In his paper, a high power DC-Donverer is proposed, using a cener-apped ransformer and full-wave ype recifier. simple resonan circui, composed of a clamp capacior and resonan inducor, is used for sof-swiching of he converer primary, wih he unipolar PWM echnique. The proposed converer reduces freewheeling conducion loss,using he unipolar PWM echnique, and a simple resonan circui. Thus, he proposed converer achieves high efficiency. However, he proposed converer uilizes he unipolar PWM echnique, like he convenional full-bridge DC-Donverer. Because he proposed converer is composed of a full-bridge circui, cener-apped ransformer, and full-wave ype recifier, he srucure of he proposed converer is simple. In his paper, he operaional principle is explained in deail,according o each operaion mode; and a design example of a prooype of he proposed converer is shown. Experimenal resuls based on he implemened Copyrigh c 2014 SERSC 275
prooype are shown, o confirm he validiy of he proposed converer. The proposed converer shows good performance as a high power DC-Donverer. cknowledgemens This work was suppored by he Soonchunhyang Universiy Research Fund. References [1] J. G. Cho, J. W. Baek, C. Y. Jeong, D. W. Yoo and K. Y. Joe, IEEE Trans on Power Elecronics, vol. 2, no. 250, (2000). [2] G. B. Koo, G. W. Moon and M. J. Youn, IEEE Trans on Power Elecronics, vol. 2, no. 411, (2004). [3] W. Chen, F. C. Lee, M. M. Jovanovic and J.. Sabae, Comparaive Sudy of a Class of Full Bridge Zer- Volage-Swiched PWM Converers, in Proc. IEEE PEDES, (1996), pp. 20-26. [4] R. Redl, N. O. Sokal and L. Balogh, Novel Sof-Swiching Full-Bridge DC/DC Converer: nalysis, Design Consideraions, and Experimenal Resuls a 1.5kW, 100kHz, IEEE nnual Conf. PESC 90, (1990), pp. 162. [5] R. yyanar and N. Mohan, IEEE Trans on Power Elecronics, vol. 2, no. 184, (2001). [6] P. K. Jain, W. Kang, H. Soin and Y. Hi, IEEE Trans on Power Elec, vol. 5, no. 649, (2002). [7] G. B. Koo, G. W. Moon and M. J. Youn, IEEE Trans on Indusrial Elecronics, vol. 1, no. 228, (2005). [8] S. -Y. Lin and C. -L. Chen, IEEE Trans on Indusrial Elecronics, vol. 2, no. 358, (1998). [9] W. Li, Y. Shen, Y. Deng and X. He, ZVZCS Full-Bridge DC/DC Converer wih a Passive uxiliary Circui in he Primary Side, in Proc. IEEE PESC, (2006), pp. 1-6. [10] X. Huang, X. Wang, T. Nergaard, J. Lai, X. Xu and L. Zhu, IEEE Trans on Power Elecronics, vol. 5, no. 1341, (2004). [11] G. Y. Jeong, D. H. Yoo and M. G. Kim, Journal of KIIT, vol. 11, no. 5, (2013). [12] C. W. Lee, S. J. Lee, M. C. Kim, Y. S. Kyung and K. H. Eom, IJST, vol. 36, (2011), pp. 15. [13] S. Banerjee, M. Mukherjee and J. P. Banerjee, IJST, SERSC, vol. 16, (2010), pp. 11. [14] K. Somsai, N. Voraphonpipu and T. Kulworawanichpong, SERSC, IJC, vol. 2, (2013), pp. 65. [15] M. li, S. Khan, M. Waleed and Islamuddin, SERSC IJST, vol. 48, no. 139 (2012). Min-Gi Kim uhors Min-Gi Kim received his B.S. degree in Elecronic Informaion Engineering in 2013 from Soonchunhyang Universiy, Korea, where he is currenly working oward he M.S. degree. His research ineress include DC-DC power converer, C-DC high frequency inverer, and power conversion for he renewable energy. Geun-Yong Park Geun-Yong Park received his B.S. degree in Elecronic Informaion Engineering in 2013 from Soonchunhyang Universiy, Korea, where he is currenly working oward he M.S. degree. His research ineress include DC-DC power converer, C-DC high frequency inverer, and power conversion for he renewable energy. 276 Copyrigh c 2014 SERSC
Doo-HeeYoo Doo-HeeYooreceived his B.S. and M.S. degrees in Elecronic Informaion Engineering from Soonchunhyang Universiy, Korea, in 2007 and2009, respecively, where he is currenly working oward he Ph.D. degree. His research ineress include DC-DC power converer, C-DC high frequency inverer, and power conversion for he renewable energy. Gang-YoulJeong Gang-YoulJeong received his B.S. degree in Elecrical Engineering from Yeungnam Universiy, Korea, in 1997, and his M.S. and Ph.D. degrees in Elecronic and Elecrical Engineering from POSTECH (Pohang Universiy of Science and Technology), Korea, in 1999 and 2002, respecively. He has been an associae professor in Deparmen of Elecronic Informaion Engineering, SoonchunhyangUniversiy, Korea. His research ineress include DC-DC power converer, C-DC high frequency inverer, and power conversion for he renewable energy. Copyrigh c 2014 SERSC 277
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