Lossless DC DC Boost Converter With High Voltage Gain For PV Technology Falah Al Hassan*, Vladimir L. Lanin *Electrical and Electronics Engineering Department, Eastern Mediterranean University, Famagusta, Cyprus, Email: falahalzobe@yahoo.com Electronic Technique and Technology Department, Belarus State University of Informatics and Radio electronics, Minsk, Belarus, Email:vlanin@bsuir.by Abstract The demands of PV technology with high performance is very interesting alternative on supplement the electric system generation, due to the persistent cost reduction of the overall system a lot of works have been done during the design and implementation of high efficiency DC-DC converters applicable in PV. This paper proposes for improving the power-conversion efficiency and to obtain high voltage gain by reducing voltage stresses at a switch node of boost converter by using snubber cell which consists of inductors, capacitor, as well as diodes. In the proposed converter, two inductors with same level of inductance are charged in parallel during the switch on period and are discharged in series during the switch-off period. Moreover the paper discusses the theoretical analyses in detail and present experimental result. Finally The improved boost converter topology was built in the laboratory to verify the performance with input voltage 15V to out 130 V and the typical operation frequency 30KHZ to get hold of efficiency between (90-94)%. Semiconductor power devices need snubber circuits because they have a limited safe operating area at turn-on and turn-off. The objective of a snubber circuit is to help the device during the switching transitions to survive the voltage and the current stresses. These stresses are due to the interruption of the current at turn-off and to the collapse of the voltage at turn-on. Numerous topologies of snubber circuits are available in the literature [4]-[6]. keywords PV,DC-DC boost converter, high voltage gain snubber circuit, high efficiency. P I. INTRODUCTION hotovoltaic PV power systems are one of today s fastest growing renewable energy technologies. Solar cells, which are the foundation of PV systems, convert the energy in sunlight directly into electricity. A number of solar cells electrically connected to each other and mounted in a support structure or frame is called a photovoltaic module. Modules are designed to supply electricity at a certain voltage. Multiple modules can be wired together to form an array [1]-[3]. In distributed generation (DG) systems, interfacing photovoltaic (PV) energy based sources to the grid poses a number of problems. Nowadays, transformerless converters are preferred for higher efficiency, low size low device stresses, and low current ripple. The output voltage of PV arrays is relatively low, requiring a high step-up converter to obtain the DC voltage input of the inverter. The PV power generation block diagram is composed of PV, Boost DC-DC Converter, energy storage element, and bidirectional DC-DC converter, as depicted in Fig. 1 Fig.1. PV power generation block diagram. Many step-up switch structures have been presented to provide a high efficiency without extremely high duty ratio and for reducing the output current ripple [8]-[10].the basic step-up inductors block is given in fig.2. Accordingly, for this block during the switch on period and are charged in parallel as shown in fig.2a and during off period and are charged in series as shown in fig.2a. September 2012 ATE-10216041 Asian-Transactions 24
[ ][ ] (2) [ ] (3) Where : Fig.2. Inductors block.( a) inductors block when switch turn on (b) inductors block when switch turn off II. OPERATIONAL ANALYSIS OF PROPOSED BOOST CONVERTER The configuration topology of the proposed converter with soft switching scheme is shown in Fig.3, the switch,,,,,, and are the main boost converter components, while R represents the resistive load on the converter. Inductor,,, and form the auxiliary circuit for accomplishing the soft switching of. Inductors and are much smaller than, and is much smaller than. When stops conducting and this stage comes to an end. 2) Stage 2: The initial conditions on, and are,, respectively, attained at the end of. Stage 1.The expressions are Eq. 4-6: [ ] (4) [ ] (5) [ ] (6) Where: Fig.3. The proposed high voltage gain dc-dc boost converter The operating stages of the proposed topology can be divided into seven stages: 1) Stage 1: This stage begins with the turn on of, at zero current at.the expressions are Eq. 1-3: Where and with the same level of inductance are charged parallel. This stage comes to an end when reaches zero at. (1) September 2012 ATE-10216041 Asian-Transactions 25
3) Stage 3: The initial conditions on, and for this stage., are zero. The expression for is: 7) Stage 7: In this stage, are zero. This stage comes to an end at when is turned on at zero current. This is the normal stage of the boost converter. The expressions are: [ ] (15) (7) This stage comes to an end at when reaches zero at. 4) Stage 4: In this stage current buildup in and and are governed by the Eq. as follows. (8) [ ] Where : (9) Where: Where is the equivalent inductance for parallel equivalent inductors and. This stage comes to an end when is turned off at zero voltage at. 5) Stage 5: This stage begins with the turn off of at zero voltage at.the expressions are: (10) [ ] (11) [ ] (12) 6) Stage 6:In this stage reduces to zero. This stage comes to an end at when becomes zero. The expression for and for these stage is. (13) Where is the equivalent inductance for equal series inductors and. III. EXPERIMENTAL RESULTS Prototype circuit is built in the laboratory To verify the theoretical analyses of proposed converter for use in PV application, the circuit specifications and components Are selected as =15V, = 70 to 130V, = 330ρF and =100µF. = =130µH, =5.4ρH, =3.3pH.Moreove r, IGBT HGTG20N60B is selected for switch s1and ultra fast diode 60EPU04P is used for,, and.moreover, two diodes 6A05 selected for and. Under the condition =15V and the switch frequency =30KHZ, some experimental results at duty cycle 80%are shown in Fig.4. and it shows that the mean power input is approximately equal 35W moreover the output voltage is equal 130V. Fig.5. shows the experimental efficiency of the proposed converter according the output voltage range. The proposed converter can achieve high step-up voltage gain as shown in Fig. 6. [ ][ ]( ) (14) September 2012 ATE-10216041 Asian-Transactions 26
IV. CONCLUSION This paper has presented a lossless dc-dc boost converter with high step-up voltage gain for the low output photovoltaic voltage. The major advantages for this topology are high boosting ratio with low voltage stress on the switch, low size and cost.the parallel/series inductors cell with snubber cell based on the active switch of proposed topology investigated and a circuit prototype with an output of 130V with efficiency (90-94)% is designed.the experimental results have proven good performances and verify the feasibility of the proposed circuit, and the voltage gain can be achieved for low output photovoltaic problem. More future work will highlight to decrease the voltage stress on the drive switch with a promising cost, size, and efficiency optimization. Fig.4. Experimental result for proposed topology ACKNOWLEDGMENT I would like to express my sincere gratitude to Mr. Said Abdalla and Ms Sabriah Halhoul and Arca family for invaluable help and support all over this work. REFERENCES Fig.5. The experimental efficiency of the proposed converter according the output voltage range [1] W. Jianqiang, and L. Jingxin, Design and experience of gridconnecting photovoltaic power system, IEEE international conference on sustainable energy technologies ICSET 2008, Pp 607-610, Singapore, 2008. [2] M. C. Cavalcanti, G. M. S. Azevedo, B. A. Amaral, K. C. de Oliveira, F. A. S. Neves, and Z. D. Lins, Efficiency evaluation in grid connected Photovoltaic energy conversion systems, IEEE 36th power electronics Specialist conference, Pp 269-275, Brazil, 2005. [3] S. Mekhilef, N. A. Rahim, and A. M. Omer, A new solar energy conversion scheme implemented using grid-tied single phase inverter, Proceedings of IEEE TENCON-2000, Kuala Lumpur, Malaysia, 2000. [4] F. Al Hassan. Transformerless Battery Charger by Using Constant Current/Constant Voltage Controller. Circuits and Systems. No.2, 2012. pp. 180 186 [5] B.-T. Irving, and M.-M. Jovanovic, Analysis, design, and performance Evaluation of flying-capacitor passive lossless snubber applied to PFC boost converter, Applied Power Electronics Conference and Exposition, Vol. 1, 2002, pp. 503-508. [6] J.-H. Kim, Y.-C. Jung, S.-W. Lee, T.-W. Lee, and C.-Y. Won, Power loss Analysis of interleaved soft switching boost converter for single-phase pv-pcs, Journal of Power Electronics, Vol. 10, No. 4, pp. 335-341, Aug. 2010. [7] B. Axelrod, Y. Berkovich, and A. Ioinovici, Switched capacitor /switched inductor structures for getting transformerless hybrid dc dc pwm converters, IEEE Transactions On Circuits And Systems-I: Regular Papers, Vol. 55, No. 2, March 2008.. [8] L. S. Yang, T. J. Liang, and J. F. Chen, Transformerless DC-DC converters with high step-up voltage gain, IEEE Trans. Ind. Electron., vol. 56,no. 8, pp. 3144-3152, Aug. 2009. [9] J. K. Park, w. Y. Choi, and B. H. Kwon, Step-up DC DC converter with a resonant voltage doubler, IEEE transactions on industrial Electronics, Vol.54, Issue-6, Pp 3267-3275, 2007. [10] Yungtaek Jan, and Milan M. Jovanovic. A New Two-Inductor Boost Converter with Auxiliary Transformer, in IEEE Transactions on Power Electronics, Vol. 19, No1, January 2004, pp. 169-175. Fig.6. The proposed converter voltage gain verses duty cycle September 2012 ATE-10216041 Asian-Transactions 27
Falah AL Hassan was born in Jordan in 1978.He received the B.S of Science in the section of Electric Engineering from Princess Sumaya University for Technology / Royal Scientific Association in Jordan in 2001. And high honor M.S. degrees of Science in Electrical and Electronic Engineering from Eastern Mediterranean University in Cyprus in 2010. He is currently working toward the Ph.D. degree. He is a member of Jordan and Cyprus Section IEEE and Member of Jordanian Engineers Syndicate. He has 9years experience works: Electric Engineering Officer at the Jordanian Armed Forces / Royal Maintenance Armament, Jordan Telecommunications Company (JTC), Jordan Ministry of Energy, power system lab in Electrical and Electronic EMU. he is author of five international papers His main research interests include dc-dc converter ac-dc converter,power maintenance,design high efficiency converters for PV system, and Ultrasonic Technology. Vladimir Lanin received the PhD in Electronic Engineering at Sanct Petersburg Technical Institute, Russia in 1982. He is Dr. Sci. Tech., professor at the Electronic Engineering and Technology Department of the State University of Informatics and Radioelectronics, Minsk, Belarus. He is a member of Belarus Section IEEE. He has more than 25 years of experience in Ultrasonic Technology and Technology of Electronics Production. Basic research area: technology of electronic devices. He is the author of books: Ultrasonic Soldering in Radio and Device Production 1985, Ultrasonic Processes in Electronics Production in 2 volume 2002, and 2003, Formation of Сurrent carring Contact Connections in Electronics Devises 2007, publishing in Belarus. September 2012 ATE-10216041 Asian-Transactions 28