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IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com

IJERA (International journal of Engineering Research and Applications) is International online, ... peer reviewed journal. For more detail or submit your article, please visit www.ijera.com

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    • A. Suresh Kumar, S. Nagaraja Rao, P.Balaji / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 4, July-August 2012, pp.889-895 An Improved ZVZCS Full Bridge Converter with secondary Resonance for High Power Applications *A. Suresh Kumar **S. Nagaraja Rao ***P.Balaji *Assistant Professor, Dept. of EEE, RGMCET, Nandyal **Assistant Professor, Dept. of EEE, RGMCET, Nandyal ***P.G.Student Dept. of EEE, RGMCET, ABSTRACT- A new zero voltage and zero no-load case. Second, it has some difficulties, such currentswitching (ZVZCS) full bridge (FB) as size reduction and a design of an PWM converter is proposed to improve the electromagnetic-interference noise filter because a performance of the previously presented wide variation of the switching frequency is ZVZCS-FB-PWM converters. In the proposed necessary to control the output voltage. circuit leakage inductance of the transformer is Some modified converters based on a utilized as secondary resonance with out an conventional SRC have been presented to solve additional inductance. The ZVZCS means these problems. One is a converter that utilizes mixed operation of zero-voltage switching (ZVS) other for leading-leg switches and zero-current control methods without additional hardware [22]– switching (ZCS) for lagging-leg switches. The [24]. By using a control method in [22], regulation primary side of the converter is composed of FB problems under low-power conditions can be insulated-gate bipolar transistors, which are solved, but the range of the operating frequency is driven by phase-shift control. The secondary still wide. Another presented approach is the phase- side is composed of a resonant tank and a half- shift control of SRC, such as the ZVS FB wave rectifier. Without an auxiliary circuit, converters in [23] and [24]. The ZVS FB zero-voltage switching (for leading-leg switches) converters can achieve constant-frequency and zero-current switching (for lagging-leg operation, no regulation problem, and ZVS of all switches) are achieved in the entire operating switches that are composed of MOSFETs. Because range. These days, IGBTs are replacing all switches of the converters are MOSFETs, the MOSFETs for high voltage, high power converters are not adequate for high-power applications, since IGBTs have higher voltage conversion in the power range of several or tens of rating, higher power density, and lower cost kilowatts. To apply the converter for high-power compared to MOSFETs. The analysis and conversions, further improvements, such as design considerations of the proposed converter applying IGBTs and extending the soft-switching are presented. range, are necessary.I. INTRODUCTION The proposed converter has several IN high-frequency and high-power advantages over existing converters. First, the converters, it is desirable to use insulated-gate leading-leg switches can be turned on softly under bipolar transistors (IGBTs) for primary switches almost all operating conditions, and a lossless turn- and to utilize soft-switching techniques such as off snubber can be used to reduce turn-off loss. zero voltage switching (ZVS) and zero-current Second, the lagging-leg switches can be turned on switching (ZCS)[1]-[24]. IGBTs can handle higher at zero voltage and also turned off near zero current voltage and higher power with lower cost without additional auxiliary circuits. Third, the compared with MOSFETs, so IGBTs have been reverse-recovery currents of the diodes are Replacing MOSFETs in applications requiring significantly reduced, and the voltage stresses of several or several tens of kilowatt power. In high- the output diodes are clamped to the output voltage. frequency converters, soft-switching techniques are Therefore, last, the switching loss of the converter widely used to reduce the switching loss that is very low, and the converter is adequate for high- results from high switching frequency. voltage and high-power applications. Among previous soft-switching FB converters, a series-resonant converter (SRC) [14]– II. PRINCIPAL OF OPERATION [21] is the simplest topology. Moreover, because The operation of the converter in Fig. 1 is all switches of the converter are turned on at zero analyzed in this section. The output voltage Vo of voltage, the conversion efficiency is relatively the converter is controlled as in a conventional high. However, the SRC has some drawbacks. phase-shifted FB converter. The converter has six First, the output voltage cannot be regulated for the operation modes within each switching period Ts. 889 | P a g e
    • A. Suresh Kumar, S. Nagaraja Rao, P.Balaji / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 4, July-August 2012, pp.889-895The operation waveforms and equivalent circuits Mode 2 [t1, t2]: At t1, the lagging-leg switch T2 isare shown in Figs. 2 and 3, respectively. To turned off when iT2 = −im. Because im is a veryanalyze the operation of the converter, several low current, T2 is turned off near zero current.assumptions are made in the following. After a short dead time, B2 is turned on at zero1) Leading-leg switches T1 and B1 and lagging-leg voltage, while the current ip flows through theswitches T2 and B2 are ideal, except for their body body diode of B2. During this mode, the secondarydiodes. voltage across N2 is nVin. Therefore, is builds up2) Because the output capacitor Co is very large, from its zero value and flows through D1. The statethe output voltage Vo is a dc voltage without any equations can be written as follows:ripple.3) Transformer T is composed of ideal transformers dis t N1 and N2, a magnetizing inductance Lm, and a Llk  V0  vc t   nVinleakage inductance Llk. dt d V0  vc t   is t 4) Since the capacitances of lossless turn-offsnubber (CT1 and CB1) are very small, the Cr dt is t   0transient time of charging and discharging isneglected. (2)5) When the switching frequency fs is less than the where vc is a voltage across Cr. Thus, is is obtainedresonant frequency fr, the conduction loss is large asunnecessarily due to the high peak currents of the nVin  V0  vc t1 devices. Therefore, we assume that fs ≥ fr. is t   sin r t  t1  (3)The voltage across N2 is given as three-level Z0voltages: nVin, 0, and −nVin by the phase-shift where the angular resonance frequencycontrol of the primary switches, where n is the 1transformer turn ratio N2/N1 and Vin is the input r  2f r  (4)voltage. The series-resonant tank is formed by Llk Llk Crand a resonant capacitor Cr, the secondary current and the characteristic impedanceis through theresonant circuit is half-wave rectified by therectifying diodes D1 and D2, and the positive valueof is feeds the output stage. Fig. 1. Proposed soft-switching FB converter with secondary resonance.A detailed mode analysis is as follows.Mode 1 [t0, t1]: As shown in Figs. 2 and 3, topswitches T1 and T2 are ON state, and is becomeszero at t0. During this mode, diodes D1 and D2 areOFF state, and the current is remains zero. Becausethe voltages across both N1 and N2 are zero, themagnetizing current im is constant. The followingequalities are satisfied.       im t  i p t  iT 1 t  iT 2 t  im t2 (1) Fig:2 :operational waveforms of proposed converter Where ip is the primary current and iT1 is the Lrsum of the currents of T1, its body diodes DT1’s, Z0  (5)and its snubber capacitanceCT1. Similarly, iT2, CriB1, and iB2 are defined. the currents of body The magnetizing current im is increased linearly bydiodes are simply the negative portions of iT1, iT2, the input voltage asiB1, and iB2. 890 | P a g e
    • A. Suresh Kumar, S. Nagaraja Rao, P.Balaji / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 4, July-August 2012, pp.889-895 The primary current of the conventional ZVSim t   im t1   in t  t1  V (6) FB converter is compared with the ip of the Lm proposed converter(Fig.2).The conventional ZVSThe following equalities are also satisfied: FB converter uses a large leakage inductor toi p t   im t   nis t   iT 1 t   iB 2 t  (7) achieve the ZVS of the lagging–lag switches in a wide operating range. The large leakage inductor causes higher circulating energy that significantlyMode 3 [t2, t3]: At t2, T1 is turned off increases the conduction loss and further reduces.Subsequently, the current ip charges CT1 and the effective duty ratio. On the other hand, in thedischarges CB1. Once the collector–emitter voltage proposed converter, the effective duty ratio is notof B1 reaches zero, the current ip flows through the reduced, and the conduction loss from thebody circulating energy is relatively low by resetting the secondary current during Mode 3 [25], [26]. To analyze the converter, two quantities are defined as frequency ratio fr F (10) fs and quality factor 4r Llk Q (11) R0 III. Analysis of ZVS and ZCS Conditions In almost the entire operating range, leading-leg switches T1 and B1 are naturally turned on at zero voltage by the reflected current is, as shown in Fig. 2. However, to achieve ZVS and ZCS in lagging-leg switches T2 and B2, Modes 1 and 4 have to exist, as shown in Fig. 2. In other words, the secondary current must be zero before the switching of T2 and B2. Assuming that F ≤ 1, there are three possible waveforms of the secondary current, as shown in Fig. 5. When the waveform of is is similar to Fig. 4(b), the lagging- lag switches cannot be turned off softly at zero current. On the other hand, when the waveform of is is similar to Fig. 4(c), T2 and B2 cannot be turned on at zero voltage. To achieve the waveform of Fig. 5(a), which is different from that of Fig. 5(b), is must reach zero while the secondary Fig3: Modes of operation voltage across N2 is zero. Thus, t3, which satisfies (12), must existdiode of B1. After dead time, B1 is turned on atzero voltage. Because the voltage across N2 is zero, nVin  V0  vc t1 is goes to zero. The state equation is the same as im t3   sin r t 2  t1  cos r t3  t 2  Z0(2), except for the initial condition of is and the V0  vc t 2 applied voltage across N2.Thus, the current is can  sin r t3  t 2  (12)be obtained analogously with (3) as Z0 0 V  v t is t   is t2 cos r t  t2   0 c 2 sin r t  t2  (8) To achieve the waveform of Fig. 4(a), which Z0 is different from that of Fig. 4(c), the peak-to-peakThe following equalities are also satisfied: value of the ripple voltage of Cr must be lower i p t   im t   nis t   iB1 t   iB 2 t  than Vo. In other words, vc(t1), which is the(9) minimum value of vc, must be positive to avoid theAt the end of Mode 3, is becomes zero. conduction of D2 during Mode 4.Explanations of Modes 4–6 are omitted becausethese modes are similar to Modes 1–3, respectively. 891 | P a g e
    • A. Suresh Kumar, S. Nagaraja Rao, P.Balaji / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 4, July-August 2012, pp.889-895 turned on must be greater than the energy stored in the Coss of T2 and B2 as 1  im  2 Lm    CossVin 2 2  2  (15) Where vin im  (16) 2 Lm f s Therefore, Lm can be determined asFig. 4: Three possible waveforms of the secondary  min 2 current is. (a) Waveform of is when IGBTs can be Lm  turned on and off softly. (b) Waveform of is when 32Cossfs2IGBTs cannot be turned off softly. (c) Waveform of (17) is when IGBTs cannot be turned on softly. where ϕmin is the minimum value of Therefore, from (12), thfollowing ϕ satisfying the ZVS of T2 and B2. Anotherinequality must be satisfied: condition of the ZVS of the lagging-lag switches is V0    V0  vc t1   1  FQ   0 (13) that the dead time of the lagging leg should be 2 2  short enough since the lagging-leg switches should be turned on while the current flows through the body diodes. The dead time can simply be determined by experiment. IV. SIMULATION RESULTS A prototype of the proposed converter was simulated through matlab. The converter was tested with Vin = 250 V, Vo = 550 V, and output power Po = 1.3 kW; further design parameters are given in Table I. Fig: 6(a)&(b) shows the zero voltage and zero current i.e. soft switching waveforms of the leading leg and lagging leg switches. Fig. 5:Operation waveforms when Q is greater TABLE 1: Simulation Parameters than 2/πF.Therefore, the ZVS condition of T2 and B2 isobtained as 2 Q (14) F In practical situations, Q may becomegreater than 2/πF under overload conditions. Fig. 7shows the operation waveforms when Q > 2/πF.Because ZVS cannot be achieved in the lagging-leg switches, switching loss results from the body-diode reverse-recovery current and the dissipatedenergy of the parasitic output capacitances, asshown in Fig. 7.However, in IGBTs, the loss resulting from non-ZVS is not large. In real switches, there are Fig: 6(a) soft switching waveforms of leading legparasitic output capacitances Coss’s. Therefore, switchesanother ZVS condition of the lagging-leg switchesis that the energy stored in Lm before T2 and B2 are 892 | P a g e
    • A. Suresh Kumar, S. Nagaraja Rao, P.Balaji / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 4, July-August 2012, pp.889-895 REFERENCES [1] X. Wu, J. Zhang, X. Ye, and Z. Qian,PERAMETERS SYMBOL VALUE ―Analysis and derivations for a familyInput voltage range Vin 250V ZVS converter based on a new activeOutput voltage V0 550V clamp ZVS cell,‖ IEEE Trans. Ind.Output power P0 1.3KW Electron., vol. 55, no. 2, pp. 773–781,Magnetizing Lm 300μH Feb. 2008.inductance [2] J. J. Lee, J. M. Kwon, E. H. Kim, and B.Leakage inductance Llk 15.7µH H. Kwon, ―Dual seriesresonant active-Quality factor at rated Q 0.62 clamp converter,‖ IEEE Trans. Ind.condition Electron., vol. 55, no. 2, pp. 699–710,Resonant frequency fr 38.3kHz Feb. 2008.Switching frequency fs 38.3kHz [3] B. R. Lin and C. H. Tseng, ―Analysis ofResonant capacitor Cr 1.1µF parallel-connected asymmetrical soft-Snubber capacitor CT1,CB1 6.8nF switching converter,‖ IEEE Trans. Ind. Electron., vol. 54, no. 3, pp. 1642–1653, Jun. 2007. [4] C. M. Wang, ―A novel ZCS-PWM flyback converter with a simple ZCSPWM commutation cell,‖ IEEE Trans. Ind. Electron., vol. 55, no. 2, pp. 749–757, Feb. 2008. [5] P. Das and G. Moschopoulos, ―A comparative study of zero- currenttransition PWM converters,‖ IEEE Trans. Ind. Electron., vol. 54, no. 3, pp. 1319–1328, Jun. 2007. [6] G. C. Jung, H. R. Geun, and F. C. Lee, ―Zero-voltage and zero-currentswitching full-bridge PWM converter using Fig: 6(b) soft switching waveforms of lagging leg secondary active clamp,‖ in Proc. IEEE switches PESC, 1996, vol. 1, pp. 657–663. [7] J. Zhang, X. Xie, X. Wu, G. Wu, and Z. Qian, ―A novel zero-currenttransition full bridge DC/DC converter,‖ IEEE Trans. Power Electron., vol. 21, no. 2, pp. 354–360, Mar. 2006. [8] T. T. Song and N. Huang, ―A novel zero- voltage and zero-currentswitching full- bridge PWM converter,‖ IEEE Trans. Power Electron., vol. 20, no. 2, pp. 286– 291, Mar. 2005. [9] E. S. Kim and Y. H. Kim, ―A ZVZCS PWM FB DC/DC converter using a modified energy-recovery snubber,‖ IEEE Trans. Ind. Electron., vol. 49, no. 5, pp. 1120–1127, Oct. 2002. Fig7: output voltage and current waveforms [10] K. W. Seok and B. H. Kwon, ―An improved zero-voltage and zerocurrent- V . CONCLUSION switching full-bridge PWM converter The operation of the proposed using a simple resonantcircuit,‖ IEEEconverter is analyzed. And the experimental results Trans. Ind. Electron., vol. 48, no. 6, pp.of a 1.2KW prototype prove the novel converter is 1205–1209, Dec. 2001.successful. The efficiency attained under full-load [11] X. Wu, X. Xie, C. Zhao, Z. Qian, and R.conditions was over 95.5%. The converter may be Zhao, ―Low voltage and current stressadequate for high-voltage and high-power ZVZCS full bridge DC–DC converterapplications (> 10 kW) since the converter has using center tapped rectifier reset,‖ IEEEmany advantages, such as minimum number of Trans. Ind. Electron., vol. 55, no. 3, pp.devices, soft switching of the switches, no output 1470–1477, Mar. 2008.inductor, and so on. 893 | P a g e
    • A. Suresh Kumar, S. Nagaraja Rao, P.Balaji / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 4, July-August 2012, pp.889-895[12] J. Dudrik, P. Spanik, and N. D. Trip, DC–DC power converter,‖ in Proc. IEEE ―Zero-voltage and zero-current switching APEC, 1988, pp. 360–367. full-bridge DC–DC converter with [24] W. J. Lee, C. E. Kim, G. W. Moon, and S. auxiliary transformer,‖ IEEE Trans. K. Han, ―A new phaseshifted full-bridge Power Electron., vol. 21, no. 5, pp. 1328– converter with voltage-doubler-type 1335, Sep. 2006. rectifier for highefficiency PDP sustaining[13] X. Wu, X. Xie, C. Zhao, Z. Qian, and R. power module,‖ IEEE Trans. Ind. Zhao, ―Low voltage and current stress Electron., vol. 55, no. 6, pp. 2450–2458, ZVZCS full bridge DC–DC converter Jun. 2008. using center tapped rectifier reset,‖ IEEE [25] B. H. Kwon, J. H. Kim, and G. Y. Jeong, Trans. Ind. Electron., vol. 55, no. 3, pp. ―Full-bridge soft switching PWM 1470–1477, Mar. 2008. converter with saturable inductors at the[14] R. L. Steigerwald, ―A comparison of half- secondary side,‖ Proc. Inst. Elect.Eng.— bridge resonant converter topologies,‖ Elect. Power Appl., vol. 146, no. 1, pp. IEEE Trans. Power Electron., vol. 3, no. 117–122, Jan. 1999. 2, pp. 174–182, Apr. 1998. [26] J. G. Cho, J. A. Sabate, H. Guichao, and F.[15] R. L. Steigerwald, R.W. De Doncker, and C. Lee, ―Zero-voltage and zero-current- H. Kheraluwala, ―A comparison of high- switching full-bridge PWM converter for power DC–DC soft-switched converter high power applications,‖ in Proc. IEEE topologies,‖ IEEE Trans. Ind. Electron., PESC, 1994, vol. 1, pp. 102–108. vol. 32, no. 5, pp. 1136–1145, Sep./Oct. [27] T. T. Song, N. Huang, and A. Ioinovici, 1996. ―A zero-voltage and zero-current[16] M. Borage, S. Tiwari, and S. Kotaiah, switching three-level DC–DC converter ―LCL-T resonant converter with clamp with reduced rectifier voltage stress and diodes: A novel constant-current power soft-switching-oriented optimized design,‖ supply with inherent constant-voltage IEEE Trans. Power Electron., vol. 21, no. limit,‖ IEEE Trans. Ind. Electron., vol. 54, 5, pp. 1204–1212, Sep. 2006. no. 2, pp. 741–746, Apr. 2007. [28] T.-F. Chen and S. Cheng, ―A novel zero-[17] M. Z. Youssef and P.K. Jain, ―Series– voltage zero-current switching full-bridge parallel resonant converter in selfsustained PWM converter using improved oscillation mode with the high-frequency secondary active clamp,‖ in Proc. IEEE transformer-leakageinductance effect: Int. Symp. Ind. Electron., Jul. 9–13, 2006, Analysis, modeling, and design,‖ IEEE vol. 3, pp. 1683–1687. Trans. Ind Electron., vol. 54, no. 3, pp. [29] E. Adib and H. Farzanehfard, ―Family of 1329–1341, Jun. 2007. zero-current transition PWM converters,‖[18] J. T. Matysik, ―The current and voltage IEEE Trans. Ind. Electron., vol. 55, no. 8, phase shift regulation in resonant pp. 3055–3063, Aug. 2008. converters with integration control,‖ IEEE [30] E. H. Kim and B. H. Kwon, ―High step-up Trans. Ind. Electron., vol. 54, no. 2, pp. push-pull converter with high efficiency,‖ 1240–1242, Apr. 2007. IET Power Electron., vol. 2, no. 1, pp. 79–[19] S. Zheng and D. Czarkowski, ―Modeling 89, Jan. 2009. and digital control of a phasecontrolled [31] Y. Tsuruta, Y. Ito, and A. Kawamura, series–parallel resonant converter,‖ IEEE ―Snubber-assisted zero-voltage and zero- Trans. Ind. Electron.,vol. 54, no. 2, pp. current transition bilateral buck and boost 707–715, Apr. 2007. chopper for EV drive application and test[20] R. Oruganti and F. C. Lee, ―Resonant evaluation at 25 kW,‖ IEEE Trans. Ind. power processors. Part I—State plane Electron., vol. 56, no. 1, pp. 4–11, Jan. analysis,‖ IEEE Trans. Ind. Appl., vol. IA- 2009. 21, no. 6, pp. 1453–1460, Nov. 1985. [32] J. L. Russi, M. L. S. Martins, and H. L.[21] G. Spiazzi and L. Rossetto, ―Series Hey, ―Coupled-filter-inductor soft- resonant converter with wide load range,‖ switching techniques: Principles and in Proc. IEEE Ind. Appl. Soc. Conf., 1998, topologies,‖ IEEE Trans. Ind. Electron., vol. 2, pp. 1326–1331. vol. 55, no. 9, pp. 3361–3373, Sep. 2009.[22] S. Dalapati, S. Ray, S. Chaudhuri, and C. [33] T. Citko and S. Jalbrzykowski, ―Current- Chakraborty, ―Control of a series resonant fed resonant full-bridge boost DC/AC/DC converter by pulse density modulation,‖ in converter,‖ IEEE Trans. Ind. Electron., Proc. IEEE INDICO, 2004, pp. 601–604. vol. 55, no. 3, pp. 1198–1205, Mar. 2008.[23] J. G. Hayes, N. Mohan, and C. P. Henze, ―Zero-voltage switching in a constant frequency digitally controller resonant 894 | P a g e
    • A. Suresh Kumar, S. Nagaraja Rao, P.Balaji / International Journal of Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.com Vol. 2, Issue 4, July-August 2012, pp.889-895 A.Suresh Kumar was born in kurnool, India. He received the B.Tech (Electrical and Electronics Engineering) degree from the Jawaharlal Nehru TechnologicalUniversity, Hyderabad in 2005; M.Tech (PowerElectronics & Drives) from the Veluru Institute ofTechnology in 2008.He is currently anAsst.Professor of the Dept. of Electrical andElectronic Engineering, R.G.M College ofEngineering and Technology, Nandyal. His area ofinterest power electronics and Electric Drives andResonant converters. S.Nagaraja Rao was born in kadapa, India. He received the B.Tech (Electrical and Electronics Engineering) degree from the Jawaharlal Nehru Technological University, Hyderabad in 2006;M.Tech (Power Electronics) from the sameuniversity in 2008.He is currently working as anAsst.Professor of the Dept. of Electrical andElectronic Engineering, R.G.M College ofEngineering and Technology, Nandyal. His area ofinterest power electronics and Electric Drives.. P.BALAJI was born in kadapa,India.He received the B.Tech (Electrical and Electronics Engineering) degree from the Jawaharlal Nehru Technological University, Anantapur in 2009 .Currently perusing M-Tech (power Electronics), inRajeev Gandhi Memorial College of Engg. &Tech,Nandyal. 895 | P a g e