A Novel Bidirectional DC-DC Converter with Battery Protection

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A Novel Bidirectional DC-DC Converter with Battery Protection

  1. 1. International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.6, Nov-Dec. 2012 pp-4261-4265 ISSN: 2249-6645 A Novel Bidirectional DC-DC Converter with Battery Protection Srinivas Reddy Gurrala1, K.Vara Lakshmi2 1(PG Scholar Department of EEE, Teegala Krishna Reddy Engineering college, JNTU- Hyd, AP, INDIA)2 (Assistant professor Department of EEE, Teegala Krishna Reddy engineering college, JNTU-Hyd, AP, INDIA)ABSTRACT: This paper presents the implementation of order to analyze the steady-state characteristics of thea bidirectional dc-dc converter to protect a battery from proposed converter, some conditions are assumed: Theovercharging and undercharging. The proposed converter ON-state resistance 𝑅 𝐷𝑆(𝑂𝑁) of the switches and thecircuit provides low voltage stresses across the switches, equivalent series resistances of the coupled inductor andhigher step-up and step-down voltage gains and efficiency capacitors are ignored; the capacitor is sufficiently large;is also high when compared to conventional boost/buck and the voltages across the capacitor can be treated asconverter. The proposed control circuit controls the constant.charging and discharging of the battery. The operatingprinciple and steady state analysis for the step-up and II. CIRCUIT CONFIGURATION ANDstep-down modes are discussed only in continuous STEADY STATE ANALYSISconduction mode. Finally, 13/39-V prototype circuit is A. STEP-UP MODEimplemented to verify the performance of proposed Fig. 1 shows the conventional bidirectional dc-dcconverter. boost/buck converter. The proposed converter in step-up mode is shown in Fig. 2. The pulse-width modulationKeywords: Battery, Bidirectional dc–dc converter, (PWM) technique is used to control the switches 𝑆1 and 𝑆2coupled inductor. simultaneously. The switch 𝑆3 is the synchronous rectifier. I. INTRODUCTION BIDIRECTIONAL dc–dc converters are used totransfer the power between two dc sources in eitherdirection. These converters are widely used inapplications, such as hybrid electric vehicle energysystems, uninterrupted power supplies, fuel-cell hybridpower systems, photovoltaic hybrid power systems, andbattery chargers. Many bidirectional dc–dc convertershave been researched. The bidirectional dc–dc flybackconverters are more attractive due to simple structure andeasy control [2], [10]. However, these converters sufferfrom high voltage stresses on the power devices due to theleakage inductor energy of the transformer. In order to Fig1.Conventional bidirectional DC-DC boost/buckrecycle the leakage inductor energy and to minimize the convertervoltage stress on the power devices, some literaturespresent the energy regeneration techniques to clamp thevoltage stress on the power devices and to recycle theleakage inductor energy [11], [12]. Some literaturesresearch the isolated bidirectional dc–dc converters,which include the half bridge [5], [6] and full-bridgetypes [9].These converters can provide high step-up andstep-down voltage gain by adjusting the turns ratio of thetransformer. For non-isolated applications, the non-isolatedbidirectional dc–dc converters, which include theconventional boost/buck [1], [4], [8], multilevel [3], three-level [7],sepic/zeta [16], switched capacitor [17], andcoupled inductor types [18], are presented. The multileveltype is a magnetic-less converter, but 12 switches are used Fig.2.Proposed converter in step-up modein this converter. If higher step-up and step-down voltagegains are required, more switches are needed. Since the primary and secondary winding turns of the The total system is useful to avoid the damage to the coupled inductor is same, the inductance of the coupledlife of the Batteries. Because of overcharging and inductor in the primary and secondary sides are expressedundercharging batteries will produce hot spots inside the asbattery such that the batteries not survive for long time. 𝐿1 = 𝐿2 = 𝐿 1The following sections will describe the operatingprinciples and steady-state analysis for the step-up and Thus, the mutual inductance M of the coupled inductor isstep-down modes in continuous conduction mode only. In given by www.ijmer.com 4261 | Page
  2. 2. International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.6, Nov-Dec. 2012 pp-4261-4265 ISSN: 2249-6645 𝑀 = π‘˜ 𝐿1 𝐿2 = π‘˜πΏ 2where k is the coupling coefficient of the coupled inductor.The voltages across the primary and secondary windingsof the coupled inductor are as follows: 𝑑𝑖 𝐿1 𝑑𝑖 𝐿2 𝑑𝑖 𝐿1 𝑑𝑖 𝐿2 𝑣 𝐿1 = 𝐿1 + 𝑀 = 𝐿 + π‘˜πΏ (3) 𝑑𝑑 𝑑𝑑 𝑑𝑑 𝑑𝑑 𝑑𝑖 𝐿1 𝑑𝑖 𝐿2 𝑑𝑖 𝐿1 𝑑𝑖 𝐿2 𝑣 𝐿2 = 𝑀 + 𝐿2 = π‘˜πΏ + 𝐿 (4) 𝑑𝑑 𝑑𝑑 𝑑𝑑 𝑑𝑑Fig. 3 shows some typical waveforms in continuousconduction mode (CCM). The operating principles andsteady-state analysis of CCM is described as follows.1) Mode 1: During this time interval [𝑑0 ,𝑑1 ], 𝑆1 and 𝑆2 areturned on and 𝑆3 is turned off. The energy of the low-voltage side 𝑉 𝐿 is transferred to the coupled inductor.Meanwhile, the primary and secondary windings of thecoupled inductor are in parallel. The energy stored in thecapacitor 𝐢 𝐻 is discharged to the load. Thus, the voltagesacross 𝐿1 and 𝐿2 are obtained as 𝑣 𝐿1 = 𝑣 𝐿2 = 𝑉 𝐿 (5)Substituting (3) and (4) into (5), yielding Fig.3. waveforms of proposed converter in step-up mode in CCM mode of operation 𝑑𝑖 𝐿1 (𝑑) 𝑑𝑖 𝐿2 (𝑑) 𝑉𝐿 = = , 𝑑0 ≀ 𝑑 ≀ 𝑑1 (6) 𝑑𝑑 𝑑𝑑 (1 + π‘˜)𝐿 B. STEP-DOWN MODE2) Mode 2: During this time interval [𝑑1 , 𝑑2 ], 𝑆1 and 𝑆2 areturned off and 𝑆3 is turned on. The low-voltage side 𝑉 𝐿and the coupled inductor are in series to transfer theirenergies to the capacitor 𝐢 𝐻 and the load. Meanwhile, theprimary and secondary windings of the coupled inductorare in series. Thus, the following equations are found to be 𝑖 𝐿1 = 𝑖 𝐿2 (7) 𝑣 𝐿1 + 𝑣 𝐿2 = 𝑉 𝐿 βˆ’ 𝑉 𝐻 (8) Fig.4.Proposed converter in step-down modeSubstituting (3), (4), and (7) into (8), yielding Fig. 4 shows the proposed converter in step-down 𝑑𝑖 𝐿1 (𝑑) 𝑑𝑖 𝐿2 (𝑑) 𝑉𝐿 βˆ’ 𝑉 𝐻 mode. The PWM technique is used to control the = = , 𝑑1 ≀ 𝑑 ≀ 𝑑2 (9) switch 𝑆3 . The switches 𝑆1 and 𝑆2 are the synchronous 𝑑𝑑 𝑑𝑑 2(1 + π‘˜)𝐿 rectifiers. Fig. 5 shows some typical waveforms in CCM.By using the state-space averaging method, the following The operating principle and steady-state analysis of CCMequation is derived from (6) and (9): is described as follows. 1) Mode 1: During this time interval [𝑑0 ,𝑑1 ] 𝑆3 is turned 𝐷𝑉 𝐿 1 βˆ’ 𝐷 (𝑉 𝐿 βˆ’ 𝑉 𝐻 ) on and 𝑆1 /𝑆2 are turned off. The energy of the high-voltage + =0 (10) side 𝑉 𝐻 is transferred to the coupled inductor, the 1+ π‘˜ 𝐿 2(1 + π‘˜)𝐿 capacitor 𝐢 𝐿 , and the load. Meanwhile, the primary and secondary windings of the coupled inductor are in series. Thus, the following equations are given as:Simplifying (10), the voltage gain is given as 𝑖 𝐿1 = 𝑖 𝐿2 (12) 𝑉𝐻 1 + 𝐷 𝑣 𝐿1 + 𝑣 𝐿2 = 𝑉 𝐻 βˆ’ 𝑉 𝐿 (13) 𝐺 𝐢𝐢𝑀 (𝑠𝑑𝑒𝑝 βˆ’π‘’π‘ ) = = (11) 𝑉𝐿 1 βˆ’ 𝐷 Substituting (3), (4), and (12) into (13), yielding 𝑑𝑖 𝐿1 (𝑑) 𝑑𝑖 𝐿2 (𝑑) 𝑉 𝐻 βˆ’ 𝑉𝐿 = = , 𝑑0 ≀ 𝑑 ≀ 𝑑1 (14) 𝑑𝑑 𝑑𝑑 2(1 + π‘˜)𝐿 www.ijmer.com 4262 | Page
  3. 3. International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.6, Nov-Dec. 2012 pp-4261-4265 ISSN: 2249-66452) Mode 2: During this time interval [𝑑1 , 𝑑2 ], 𝑆3 is turned With the current flow in the battery there is some resistiveoff and 𝑆1 /𝑆2 are turned on. The energy stored in the drop in electrodes and resistance offered to the movementcoupled inductor is released to the capacitor 𝐢 𝐿 and the of ions, are modeled as electrical resistances here.load. Meanwhile, the primary and secondary windings of Battery capacity is defined as the current that discharges inthe coupled inductor are in parallel. Thus, the voltages 1hour. So the battery capacity should be in Ampere-hours.across 𝐿1 and 𝐿2 are derived as In practice the relationship between battery capacity and discharge current is not linear. 𝑣 𝐿1 = 𝑣 𝐿2 = βˆ’π‘‰ 𝐿 (15)Substituting (3) and (4) into (15), yielding Peukert’s Law relates battery capacity to discharge rate: 𝑑𝑖 𝐿1 (𝑑) 𝑑𝑖 𝐿2 (𝑑) 𝑉𝐿 = =βˆ’ , 𝑑1 ≀ 𝑑 ≀ 𝑑2 (16) 𝐢 = πΌπ‘˜ 𝑑 (19) 𝑑𝑑 𝑑𝑑 (1 + π‘˜)𝐿By using the state space averaging method, the following where C is the battery capacity, I is the discharge current, tequation is obtained from (14) and (16): is the discharge time, k is the Peukert coefficient, typically 𝐷(𝑉 𝐻 βˆ’ 𝑉 𝐿 ) 1 βˆ’ 𝐷 𝑉𝐿 1.1to 1.3. βˆ’ =0 (17) The output voltage of the bidirectional dc-dc converter is 2 1+ π‘˜ 𝐿 (1 + π‘˜)𝐿 connected to the three Lead-Acid batteries which areSimplifying (17), the voltage gain is found to be connected in series. 𝑉𝐿 𝐷 Table-1: charge limits of a 12V battery 𝐺 𝐢𝐢𝑀 (𝑠𝑑𝑒𝑝 βˆ’π‘‘π‘œπ‘€π‘› ) = = (18) 𝑉𝐻 2 βˆ’ 𝐷 Fully charged Discharged completely State of charge 100% 0% Voltage 12.7V 11.6V Let a single battery fully charged voltage is 𝑉1 and completely discharged voltage will be 𝑉2 . Here three batteries of 𝑉1 each are connected in series so that the fully charge voltage (3x 𝑉1 ) V is the overcharged voltage. Similarly (3x𝑉2 ) V is the undercharged voltage. Fig.7.Battery charge controller in step-up mode Initially S4 and S5 both switches are in closed Fig.5. waveforms of proposed converter in step-down condition. Whenever the voltage across batteries is greater mode in CCM mode of operation than or equal to (3x𝑉1 ) V, switch S4 will open. Under this condition load will fed from the batteries. Means under III. ANALYSIS OF BATTERY PROTECTION overcharged condition supply to batteries and load fromThe basic model of a battery is shown in the fig.6. the bidirectional dc-dc converter is disconnected. While discharging if the voltage across the batteries is less than or equal to (3x𝑉2 ) V switch S5 will open. The total system is useful to avoid the damage to the life of batteries. Because of overcharging and undercharging batteries will not survive for long time. Fig.6. basic model of a battery www.ijmer.com 4263 | Page
  4. 4. International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.6, Nov-Dec. 2012 pp-4261-4265 ISSN: 2249-6645 source current 50 40 Isource(A) 30 20 10 0 0.9965 0.9965 0.9966 0.9966 0.9966 time Fig.10. simulation waveform for the source current Fig.8.Battery charge controller in step-down mode switch1 current 25 The output voltage of the bidirectional dc-dc 20converter is connected to a single Lead-Acid battery.The output voltage across the battery is limited by the 15 Isw1(A)battery charge controller so that controlling the chargingand discharging of the battery. The operation principle is 10same as in step-up mode. 5 IV. EXPERIMENTAL RESULTS 0 0.9965 0.9965 0.9966 0.9966 0.9966 Simulation of novel bidirectional dc-dc converter time(s)with battery protection was performed by using MATLAB Fig.11. simulation result for the switch1 currentSIMULNK to confirm the above analysis. The electricspecifications and circuit components are selected as 𝑉 𝐿 =13 V, 𝑉 𝐻 = 39 V, 𝑓𝑆 = 50 kHz, 𝑃0 = 200 W, 𝐢 𝐿 = 𝐢 𝐻 = 330 switch2 current 25ΞΌF, 𝐿1 = 𝐿2 =15.5 ΞΌH (π‘Ÿ 𝐿1 = π‘Ÿ 𝐿2 = 11 mΞ©). Also, MOSFETIRF3710 (𝑉 𝐷𝑆𝑆 = 100 V, 𝑅 𝐷𝑆(𝑂𝑁) ) = 23 mΞ©, and 𝐼 𝐷 = 57 20A) is selected for𝑆1 ,𝑆2 and 𝑆3 . ISW2(A) 15 Some experimental results in step-up mode areshown in Figs. 9-15. Fig.9 shows the waveform of the 10output voltage across the battery. It shows that the voltage 5across the battery is limited in the range of overchargingand undercharging levels. Fig.10 shows the waveform of 0 0.9965 0.9965 0.9966 0.9966 0.9966the input current. Figs.11 and 12 and 13 show the switch time(s)currents across the switches. Fig. 14 shows the waveform Fig.12. simulation result for the switch2 currentof the coupled-inductor 𝑖 𝐿1 and fig.15 shows the coupled-inductor current 𝑖 𝐿2 . The source current is double of the switch3 currentlevel of the coupled-inductor current during 𝑆1 /𝑆2 ON- 25period and equals the coupled-inductor current during 𝑆1 20/𝑆2 OFF-period. It can be observed that 𝑖 𝐿1 is equal to 𝑖 𝐿2 . ISW3(A) 15The source current equals to the coupled-inductor currentduring 𝑆3 ON-period and is double of the level of the 10coupled-inductor current during 𝑆3 OFF-period. Fig.16 5shows the output voltage across the battery. 0 0.9965 0.9965 0.9966 0.9966 0.9966 output voltage time(s) Fig.13. simulation result for the switch3 current 38 Inductor1 current 25 voltage(v) 37 36 IL1(A) 20 35 0.9965 0.9965 0.9966 0.9966 time(s) Fig.9. simulation result for the output voltage 15 0.9965 0.9965 0.9966 0.9966 0.9966 time(s) Fig.14. simulation result for the coupled inductor1 current www.ijmer.com 4264 | Page
  5. 5. International Journal of Modern Engineering Research (IJMER) www.ijmer.com Vol.2, Issue.6, Nov-Dec. 2012 pp-4261-4265 ISSN: 2249-6645 [5] G. Ma, W. Qu, G. Yu, Y. Liu, N. Liang, and W. Li, ―A zero-voltage-switching bidirectional dc–dc Inductor2 current converter with state analysis and soft-switching- 25 oriented design consideration,β€– IEEE Trans. Ind. Electron,, vol. 56, no. 6, pp. 2174–2184, Jun. 2009. [6] F. Z. Peng, H. Li, G. J. Su, and J. S. Lawler, ―A new ZVS bidirectional dc–dc converter for fuel cell and IL2(A) 20 battery application,β€– IEEE Trans. Power Electron., vol. 19, no. 1, pp. 54–65, Jan. 2004. [7] K. Jin, M. Yang, X. Ruan, and M. Xu, ―Three-level bidirectional converter for fuel-cell/battery hybrid 15 power system,β€– IEEE Trans. Ind. Electron., vol. 57, 0.9965 0.9965 0.9966 0.9966 0.9966 no. 6, pp. 1976–1986, Jun. 2010. time(s) [8] Z. Liao and X. Ruan, ―A novel power managementFig.15. simulation result for the coupled inductor2 current control strategy for stand-alone photovoltaic power system,β€– in Proc. IEEE IPEMC, 2009, pp. 445–449. output volage in step-down mode [9] S. Inoue and H. Akagi, ―A bidirectional dc–dc 14 converter for an energy storage system with galvanic isolation,β€– I EEE Trans. Power Electron., 13.5 vol. 22, no. 6, pp. 2299–2306, Nov. 2007. [10] K. Venkatesan, ―Current mode controlled voltage(v) 13 bidirectional flyback converter,β€– in Proc. IEEE Power Electron. Spec. Conf., 1989, pp. 835–842. 12.5 [11] G. Chen, Y. S. Lee, S. Y. R. Hui, D. Xu, and Y. Wang, ―Actively clamped bidirectional flyback 12 0.9965 0.9965 0.9966 0.9966 0.9966 converter,β€– IEEE Trans. Ind. Electron., vol. 47, no. 4, time(s) pp. 770–779, Aug. 2000.Fig.16. simulation result for the coupled inductor2 current [12] F. Zhang and Y. Yan, ―Novel forward-flyback hybrid bidirectional dc–dc converter,β€– IEEE Trans. V. CONCLUSION Ind. Electron., vol. 56, no. 5, pp. 1. In this paper, a novel bidirectional dc–dc converter [13] H. Li, F. Z. Peng, and J. S. Lawler, ―A natural ZVSwith battery protection is proposed. The circuit medium-power bidirectional dc–dc converter withconfiguration of the proposed converter is very simple. minimum number of devices,β€– IEEE Trans. Ind.The operation principle, including the operation modes Appl., vol. 39, no. 2, pp. 525–535, Mar. 2003.and steady-state analysis is explained in detail. The [14] B. R. Lin, C. L. Huang, and Y. E. Lee,proposed converter has higher step-up and step-down ―Asymmetrical pulse-width modulation bidirectionalvoltage gains and lower average value of the switch dc–dc converter,β€– IET Power Electron., vol. 1, no. 3,current than the conventional bidirectional boost/buck pp. 336–347, Sep. 2008.converter. From the experimental results, it is see that the [15] Y. Xie, J. Sun, and J. S. Freudenberg, ―Power flowexperimental waveforms agree with the operating principle characterization of a bidirectional galvanicallyand steady-state analysis. isolated high-power dc/dc converter over a wide operating range,β€– IEEE Trans. Power Electron., vol. REFERENCES 25, no. 1, pp. 54–66, Jan. 2010.[1] M. B. Camara, H. Gualous, F. Gustin, A. Berthon, [16] I. D. Kim, S. H. Paeng, J. W. Ahn, E. C. Nho, and J. and B. Dakyo, ―DC/DC converter design for S. Ko, ―New bidirectional ZVS PWM sepic/zeta dc– supercapacitor and battery power management in dc converter,β€– in Proc. IEEE ISIE, 2007, pp. 555– hybrid vehicle applicationsβ€”Polynomial control 560. strategy,β€– IEEE Trans. Ind. Electron.., vol. 57, no. 2, [17] Y. S. Lee and Y. Y. Chiu, ―Zero-current-switching pp. 587–597, Feb. 2010. switched-capacitor bidirectional dc–dc converter,β€–[2] T. Bhattacharya, V. S. Giri, K. Mathew, and L. Proc. Inst. Elect. Eng.β€”Elect. Power Appl., vol. 152, Umanand, ―Multiphase bidirectional flyback no. 6, pp. 1525–1530, Nov. 2005. converter topology for hybrid electric vehicles,β€– [18] R. J. Wai and R. Y. Duan, ―High-efficiency IEEE Trans. Ind. Electron., vol. 56, no. 1, pp. 78–84, bidirectional converter for power sources with great Jan. 2009. voltage diversity,β€– IEEE Trans. Power Electron., vol.[3] F. Z. Peng, F. Zhang, and Z. Qian, ―A magnetic-less 22, no. 5, pp. 1986–1996, Sep. 2007. dc–dc converter for dual-voltage automotive [19] L. S. Yang, T. J. Liang, and J. F. Chen, systems,β€– IEEE Trans. Ind. Appl., vol. 39, no. 2, pp. ―Transformerless dc–dc converters with high step-up 511–518, Mar./Apr. 2003. voltage gain,β€– IEEE Trans. Ind. Electron., vol. 56,[4] A. Nasiri, Z. Nie, S. B. Bekiarov, and A. Emadi, ―An no. 8, pp. 3144–3152, Aug. 2009.578–1584, May on-line UPS system with power factor correction and 2009. electric isolation using BIFRED converter,β€– IEEE Trans. Ind. Electron., vol. 55, no. 2, pp. 722–730, Feb. 2008. www.ijmer.com 4265 | Page

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