Inernaional Journal of Engineering Research and Developmen e-issn: 2278-067X, p-issn : 2278-800X, www.ijerd.com Volume 5, Issue 1 (November 12), PP. 46-53 A Novel Bidirecional DC-DC Converer wih Baery Proecion Harinah Vorugani 1, Dr. A.Srujana 2, K.L.N.Rao 3 1 (PG Scholar Deparmen of EEE, Sri Venkaeswara Engineering college, JNTU- Hyd, AP, INDIA) 2 (Professor Deparmen of EEE, Sri Venkaeswara engineering college, JNTU-Hyd, AP, INDIA) 3 (Associae Professor Deparmen of EEE, Indur Insiue of engineering&technology, JNTU-Hyd, AP, INDIA) Absrac:- This paper presens he implemenaion of a bidirecional dc-dc converer o proec a baery from overcharging and undercharging. The proposed converer circui provides low volage sresses across he swiches, higher sep-up and sep-down volage gains and efficiency is also high when compared o convenional boos/buck converer. The proposed conrol circui conrols he charging and discharging of he baery. The operaing principle and seady sae analysis for he sep-up and sep-down modes are discussed only in coninuous conducion mode. Finally, 13/39-V prooype circui is implemened o verify he performance of proposed converer Keywords:- Baery, Bidirecional dc dc converer, coupled inducor. I. INTRODUCTION Bidirecional dc dc converers are used o ransfer he power beween wo dc sources in eiher direcion. These converers are widely used in applicaions, such as hybrid elecric vehicle energy sysems, uninerruped power supplies, fuel-cell hybrid power sysems, phoovolaic hybrid power sysems, and baery chargers. Many bidirecional dc dc converers have been researched. The bidirecional dc dc flyback converers are more aracive due o simple srucure and easy conrol [2], [10]. However, hese converers suffer from high volage sresses on he power devices due o he leakage inducor energy of he ransformer. In order o recycle he leakage inducor energy and o minimize he volage sress on he power devices, some lieraures presen he energy regeneraion echniques o clamp he volage sress on he power devices and o recycle he leakage inducor energy [11], [12]. Some lieraures research he isolaed bidirecional dc dc converers, which include he half bridge [5], [6] and full-bridge ypes [9].These converers can provide high sep-up and sep-down volage gain by adjusing he urns raio of he ransformer. For non-isolaed applicaions, he non-isolaed bidirecional dc dc converers, which include he convenional boos/buck [1], [4], [8], mulilevel [3], hree-level [7], sepic/zea [16], swiched capacior [17], and coupled inducor ypes [18], are presened. The mulilevel ype is a magneic-less converer, bu 12 swiches are used in his converer. If higher sep-up and sep-down volage gains are required, more swiches are needed. The oal sysem is useful o avoid he damage o he life of he Baeries. Because of overcharging and undercharging baeries will produce ho spos inside he baery such ha he baeries no survive for long ime. The following secions will describe he operaing principles and seady-sae analysis for he sep-up and sep-down modes in coninuous conducion mode only. In order o analyze he seady-sae characerisics of he proposed converer, some condiions are assumed: The ON-sae resisance R DS(ON) of he swiches and he equivalen series resisances of he coupled inducor and capaciors are ignored; he capacior is sufficienly large; and he volages across he capacior can be reaed as consan. II. CIRCUIT CONFIGURATION AND STEADY STATE ANALYSIS A. STEP-UP MODE Fig. 1 shows he convenional bidirecional dc-dc boos/buck converer. The proposed converer in sep-up mode is shown in Fig. 2. The pulse-widh modulaion (PWM) echnique is used o conrol he swiches and simulaneously. The swich S 3 is he synchronous recifier. L 1 V H Fig1.Convenional bidirecional DC-DC boos/buck converer 46
A Novel Bidirecional DC-DC Converer wih Baery Proecion il i L1 L 1 V DS2 S 3 i S1 i ch I 0 i L2 L 2 V DS1 2 C H V H R H Fig.2.Proposed converer in sep-up mode Since he primary and secondary winding urns of he coupled inducor is same, he inducance of he coupled inducor in he primary and secondary sides are expressed as L 1 = L 2 = L 1 Thus, he muual inducance M of he coupled inducor is given by M = k L 1 L 2 = kl 2 where k is he coupling coefficien of he coupled inducor. The volages across he primary and secondary windings of he coupled inducor are as follows: di L1 v L1 = L 1 d + M di L2 d = L di L1 d + kl di L2 d (3) v L2 = M di L1 d + L di L2 2 d = kl di L1 d + L di L2 d (4) Fig. 3 shows some ypical waveforms in coninuous conducion mode (CCM). The operaing principles and seady-sae analysis of CCM is described as follows. 1) Mode 1: During his ime inerval [ 0, 1 ], and are urned on and S 3 is urned off. The energy of he low-volage side is ransferred o he coupled inducor. Meanwhile, he primary and secondary windings of he coupled inducor are in parallel. The energy sored in he capacior C H is discharged o he load. Thus, he volages across L 1 and L 2 are obained as v L1 = v L2 = (5) Subsiuing (3) and (4) ino (5), yielding di L1 () d = di L2() d = (1 + k)l, 0 1 (6) 2) Mode 2: During his ime inerval [ 1, 2 ], and are urned off and S 3 is urned on. The low-volage side and he coupled inducor are in series o ransfer heir energies o he capacior C H and he load. Meanwhile, he primary and secondary windings of he coupled inducor are in series. Thus, he following equaions are found o be Subsiuing (3), (4), and (7) ino (8), yielding i L1 = i L2 (7) v L1 + v L2 = V H (8) di L1 () d = di L2() d = V H 2(1 + k)l, 1 2 (9) By using he sae-space averaging mehod, he following equaion is derived from (6) and (9): D 1 + k L + 1 D ( V H ) = 0 (10) 2(1 + k)l 47
A Novel Bidirecional DC-DC Converer wih Baery Proecion Simplifying (10), he volage gain is given as G CCM(sep up ) = V H = 1 + D 1 D (11) V GS1, V GS2 V GS3 i L1, i L2 i L. i S1, i ch V DS1, V DS2 0 1 2 DT S (1 D)T S B. STEP-DOWN MODE T S Fig.3. waveforms of proposed converer in sep-up mode in CCM mode of operaion I 0 i LL i L1 L 1 V DS2 S 3 R L C L L 2 V H V DS1 2 Fig.4.Proposed converer in sep-down mode Fig. 4 shows he proposed converer in sep-down mode. The PWM echnique is used o conrol he swich S 3. The swiches and are he synchronous recifiers. Fig. 5 shows some ypical waveforms in CCM. The operaing principle and seady-sae analysis of CCM is described as follows. i S1 i L2 1) Mode 1: During his ime inerval [ 0, 1 ] S 3 is urned on and / are urned off. The energy of he high-volage side V H is ransferred o he coupled inducor, he capacior C L, and he load. Meanwhile, he primary and secondary windings of he coupled inducor are in series. Thus, he following equaions are given as: Subsiuing (3), (4), and (12) ino (13), yielding i L1 = i L2 (12) v L1 + v L2 = V H (13) di L1 () d = di L2() d = V H 2(1 + k)l, 0 1 (14) 48
A Novel Bidirecional DC-DC Converer wih Baery Proecion 2) Mode 2: During his ime inerval [ 1, 2 ], S 3 is urned off and / are urned on. The energy sored in he coupled inducor is released o he capacior C L and he load. Meanwhile, he primary and secondary windings of he coupled inducor are in parallel. Thus, he volages across L 1 and L 2 are derived as Subsiuing (3) and (4) ino (), yielding v L1 = v L2 = () di L1 () d = di L2() d = (1 + k)l, 1 2 (16) By using he sae space averaging mehod, he following equaion is obained from (14) and (16): Simplifying (17), he volage gain is found o be D(V H ) 2 1 + k L 1 D (1 + k)l = 0 (17) G CCM(sep down ) = = D V H 2 D (18) V GS3 V GS1, V GS2 i L1, i L2 i S1, i LL i cl, 2 V DS1, V DS2 0 1 2 DT S (1 D)T S Fig.5. waveforms of proposed converer in sep-down mode in CCM mode of operaion III. The basic model of a baery is shown in he fig.6. ANALYSIS OF BATTERY PROTECTION R discharg I baery V SOC R Charge V baery Fig.6. basic model of a baery 49
A Novel Bidirecional DC-DC Converer wih Baery Proecion Wih he curren flow in he baery here is some resisive drop in elecrodes and resisance offered o he movemen of ions, are modeled as elecrical resisances here. Baery capaciy is defined as he curren ha discharges in 1hour. So he baery capaciy should be in Ampere-hours. In pracice he relaionship beween baery capaciy and discharge curren is no linear. Peuker s Law relaes baery capaciy o discharge rae: C = I k (19) where C is he baery capaciy, I is he discharge curren, is he discharge ime, k is he Peuker coefficien, ypically 1.1o 1.3. The oupu volage of he bidirecional dc-dc converer is conneced o he hree Lead-Acid baeries which are conneced in series. Table-1: charge limis of a 12V baery Sae of charge Volage Fully charged Discharged compleely 100% 0% 12.7V 11.6V Le a single baery fully charged volage is V 1 and compleely discharged volage will be V 2. Here hree baeries of V 1 each are conneced in series so ha he fully charge volage (3xV 1 ) V is he overcharged volage. Similarly (3xV 2 ) V is he undercharged volage. i L1 V DS2 S 3 S 4 S 5 C i ch V 0 R i L2 L V 2 DS1 2 Baery charge conroller Fig.7.Baery charge conroller in sep-up mode Iniially S 4 and S 5 boh swiches are in closed condiion. Whenever he volage across baeries is greaer han or equal o (3xV 1 ) V, swich S 4 will open. Under his condiion load will fed from he baeries. Means under overcharged condiion supply o baeries and load from he bidirecional dc-dc converer is disconneced. While discharging if he volage across he baeries is less han or equal o (3xV 2 ) V swich S 5 will open. The oal sysem is useful o avoid he damage o he life of baeries. Because of overcharging and undercharging baeries will no survive for long ime. I 0 i Cl i LL i L1 L 1 V 0 V DS2 S 3 R L C L L 2 V H V DS1 2 i S1 i L2 Baery charge conroller Fig.8.Baery charge conroller in sep-down mode 50
Isw1(A) Isource(A) volage(v) A Novel Bidirecional DC-DC Converer wih Baery Proecion The oupu volage of he bidirecional dc-dc converer is conneced o a single Lead-Acid baery. The oupu volage across he baery is limied by he baery charge conroller so ha conrolling he charging and discharging of he baery. The operaion principle is same as in sep-up mode. IV. EXPERIMENTAL RESULTS Simulaion of novel bidirecional dc-dc converer wih baery proecion was performed by using MATLAB SIMULNK o confirm he above analysis. The elecric specificaions and circui componens are seleced as = 13 V, V H = 39 V, f S = 50 khz, P 0 = 0 W, C L = C H = 330 μf, L 1 = L 2 =.5 μh (r L1 = r L2 = 11 mω). Also, MOSFET IRF3710 (V DSS = 100 V, R DS(ON) ) = 23 mω, and I D = 57 A) is seleced for, and S 3. Some experimenal resuls in sep-up mode are shown in Figs. 9-. Fig.9 shows he waveform of he oupu volage across he baery. I shows ha he volage across he baery is limied in he range of overcharging and undercharging levels. Fig.10 shows he waveform of he inpu curren. Figs.11 and 12 and 13 show he swich currens across he swiches. Fig. 14 shows he waveform of he coupled-inducor i L1 and fig. shows he coupled-inducor curren i L2. The source curren is double of he level of he coupled-inducor curren during / ON-period and equals he coupled-inducor curren during / OFF-period. I can be observed ha i L1 is equal o i L2. The source curren equals o he coupled-inducor curren during S 3 ON-period and is double of he level of he coupled-inducor curren during S 3 OFFperiod. Fig.16 shows he oupu volage across he baery. 38 oupu volage 37 36 35 0.9965 0.9965 0.9966 0.9966 ime(s) Fig.9. simulaion resul for he oupu volage 50 source curren 40 30 10 0 ime Fig.10. simulaion waveform for he source curren swich1 curren 10 5 0 ime(s) Fig.11. simulaion resul for he swich1 curren 51
IL2(A) IL1(A) ISW3(A) ISW2(A) A Novel Bidirecional DC-DC Converer wih Baery Proecion swich2 curren 10 5 0 ime(s) Fig.12. simulaion resul for he swich2 curren swich3 curren 10 5 0 ime(s) Fig.13. simulaion resul for he swich3 curren Inducor1 curren ime(s) Fig.14. simulaion resul for he coupled inducor1 curren Inducor2 curren ime(s) Fig.. simulaion resul for he coupled inducor2 curren 52
volage(v) A Novel Bidirecional DC-DC Converer wih Baery Proecion 14 oupu volage in sep-down mode 13.5 13 12.5 12 ime(s) Fig.16. simulaion resul for he coupled inducor2 curren V. CONCLUSION In his paper, a novel bidirecional dc dc converer wih baery proecion is proposed. The circui configuraion of he proposed converer is very simple. The operaion principle, including he operaion modes and seady-sae analysis is explained in deail. The proposed converer has higher sep-up and sep-down volage gains and lower average value of he swich curren han he convenional bidirecional boos/buck converer. From he experimenal resuls, i is see ha he experimenal waveforms agree wih he operaing principle and seady-sae analysis. REFERENCES [1]. M. B. Camara, H. Gualous, F. Gusin, A. Berhon, and B. Dakyo, DC/DC converer design for supercapacior and baery power managemen in hybrid vehicle applicaions Polynomial conrol sraegy, IEEE TransInd. Elecron., vol. 57, no. 2, pp. 587 597, Feb. 10. [2]. T. Bhaacharya, V. S. Giri, K. Mahew, and L. Umanand, Muliphase bidirecional flyback converer opology for hybrid elecric vehicles, IEEE Trans. Ind. Elecron., vol. 56, no. 1, pp. 78 84, Jan. 09. [3]. F. Z. Peng, F. Zhang, and Z. Qian, A magneic-less dc dc converer for dual-volage auomoive sysems, IEEE Trans. Ind. Appl., vol. 39, no. 2, pp. 511 518, Mar./Apr. 03. [4]. [4] A. Nasiri, Z. Nie, S. B. Bekiarov, and A. Emadi, An on-line UPS sysem wih power facor correcion and elecric isolaion using BIFRED converer, IEEE Trans. Ind. Elecron., vol. 55, no. 2, pp. 722 730, Feb. 08. [5]. G. Ma, W. Qu, G. Yu, Y. Liu, N. Liang, and W. Li, A zero-volageswiching bidirecional dc dc converer wih sae analysis and sofswiching-oriened design consideraion, IEEE Trans. Ind. Elecron.,vol. 56, no. 6, pp. 2174 2184, Jun. 09. [6]. F. Z. Peng, H. Li, G. J. Su, and J. S. Lawler, A new ZVS bidirecional dc dc converer for fuel cell and baery applicaion, IEEE Trans. Power Elecron., vol. 19, no. 1, pp. 54 65, Jan. 04. [7]. K. Jin, M. Yang, X. Ruan, and M. Xu, Three-level bidirecional converer for fuel-cell/baery hybrid power sysem, IEEE Trans. Ind. Elecron., vol. 57, no. 6, pp. 1976 1986, Jun. 10. [8]. Z. Liao and X. Ruan, A novel power managemen conrol sraegy for sand-alone phoovolaic power sysem, in Proc. IEEE IPEMC, 09, pp. 445 449. [9]. S. Inoue and H. Akagi, A bidirecional dc dc converer for an energy sorage sysem wih galvanic isolaion, IEEE Trans. Power Elecron., vol. 22, no. 6, pp. 2299 2306, Nov. 07. [10]. K. Venkaesan, Curren mode conrolled bidirecional flyback converer, in Proc. IEEE Power Elecron. Spec. Conf., 1989, pp. 835 842. [11] G. Chen, Y. S. Lee, S. Y. R. Hui, D. Xu, and Y. Wang, Acively clamped bidirecional flyback converer, IEEE Trans. Ind. Elecron., vol. 47, no. 4, pp. 770 779, Aug. 00. [11]. F. Zhang and Y. Yan, Novel forward-flyback hybrid bidirecional dc dc converer, IEEE Trans. Ind. Elecron., vol. 56, no. 5, pp. 1. [12]. H. Li, F. Z. Peng, and J. S. Lawler, A naural ZVS medium-power bidirecional dc dc converer wih minimum number of devices, IEEE Trans. Ind. Appl., vol. 39, no. 2, pp. 5 535, Mar. 03. [13]. B. R. Lin, C. L. Huang, and Y. E. Lee, Asymmerical pulse-widh modulaion bidirecional dc dc converer, IET Power Elecron., vol. 1, no. 3, pp. 336 347, Sep. 08. [14]. Y. Xie, J. Sun, and J. S. Freudenberg, Power flow characerizaion of a bidirecional galvanically isolaed highpower dc/dc converer over a wide operaing range, IEEE Trans. Power Elecron., vol., no. 1, pp. 54 66, Jan. 10. []. I. D. Kim, S. H. Paeng, J. W. Ahn, E. C. Nho, and J. S. Ko, New bidirecional ZVS PWM sepic/zea dc dc converer, in Proc. IEEE ISIE, 07, pp. 555 560. [16]. Y. S. Lee and Y. Y. Chiu, Zero-curren-swiching swiched-capacior bidirecional dc dc converer, Proc. Ins. Elec. Eng. Elec. Power Appl., vol. 2, no. 6, pp. 30, Nov. 05. [17]. R. J. Wai and R. Y. Duan, High-efficiency bidirecional converer for power sources wih grea volage diversiy, IEEE Trans. Power Elecron., vol. 22, no. 5, pp. 1986 1996, Sep. 07. [18]. L. S. Yang, T. J. Liang, and J. F. Chen, Transformerless dc dc converers wih high sep-up volage gain, IEEE Trans. Ind. Elecron., vol. 56, no. 8, pp. 3144 32, Aug. 09.578 84, May 09. 53