Simulation for Step up Converter for Photovoltaic System 1. Mr. Bhushan S. Chaudhari, 2. Mr. M. Mujtahid Ansari, 3. Mr. Nilesh S. Mahajan, 1. Research Scholar, Electrical Engg. Dept, SSBT s COET, Jalgaon (MS),India. 2. Assistant Professor, Electrical Engg. Dept, SSBT s COET, Jalgaon (MS), India. 3. Assistant Professor, Electrical Engg. Dept, SSBT s COET, Jalgaon (MS), India. Abstract- Renewable energy systems which generate low voltage output thus step up converters are widely employed in so many renewable energy applications, including wind power, fuel cells and photovoltaic systems. The step up converter which performs importantly among which the system because the system requires a step up conversion. The conventional step up converters which are as the boost converter and fly back converter they can not achieve high step up conversion with high efficiency because of the resistances of elements or due to leakage inductance. This project proposed a step up converter for a photovoltaic system. Through a voltage multiplier module. An asymmetrical interleaved step up converter which obtains high step up gain. The proposed converter functions as an active clamp circuit which moderate large voltage spikes across the power switches. So the low voltage rated MOSFETs which can be adopted for reduces of conduction losses and cost. The efficiency improves because of the energy stored in leakage inductances is energized to the output terminal. Finally, such prototype circuit with a 40-V input voltage, 380-V output is operated to verify its performance. The highest efficiency is 96.8% of this converter. Keywords: Step up converter, photovoltaic system, voltage multiplier module, MPPT model, PWM converter. I. INTRODUCTION The renewable energy sources such as PV modules, fuel cells or energy storage devices such as super capacitors or batteries deliver output voltage at the range of around 12 to 70 V. In order to connect them to the grid the voltage level should be adjusted according to the electrical network standards in the countries. First of all the voltage should be stepped up to sufficient level at which the DC/AC conversion an be performed to AC mains voltage requirements[1]. Step up converter has a continuous input current flowing into the input port. Therefore, step up topology may be more suitable for PV systems to extract as much power as possible from the photovoltaic cells and energy efficiency of the step up converter is higher than that of the conventional converter [2]. Fig. 1 Typical photovoltaic system. The converter which is characterized by a low input current ripple and low conduction losses, making it suitable for high power applications. The converter achieves the step up voltage gain that renewable energy systems require. leakage energy which is recycled and sent to output terminal, and large voltage spikes on the main switch. The main switch voltage stress of the converter which is substantially lower than that of the output voltage of the converter [5] [6]. Primary windings of the coupled inductors which with Np turns are employed to decrease input current ripple and secondary windings of the coupled inductors with Ns turns are connected in series to extend voltage gain. Converter obtains extra voltage gain through the voltage lift capacitor Cb, and which reduces the input current ripple, which is suitable for power factor correction and also high power applications. An asymmetrical interleaved step up converter that combines the advantages of the aforementioned converters is proposed in which combined the advantages of both. In the voltage multiplier module of the proposed converter which has the turns ratio of coupled inductors can be designed to extend voltage gain, and also a voltage lift capacitor offers an extra voltage conversion ratio [1]. ISSN: 2231-5381 http://www.ijettjournal.org Page 29
II. OPERATING PRINCIPLE The switching period can be subdivided into six modes of operation. The modes 1-3 are same as modes 4-6 which are shown in following figures. A. Mode I C3. The input voltage source, magnetizing inductor Lm2, leakage inductor Lk2, and voltagelift capacitor Cb release energy to the output filter capacitor C1 via diode D2, there by extending the voltage on C1. C. Mode III Fig. 2 Mode I At t = t0, the power switches S1 and S2 are both turned ON. All of the diodes are reversed biased. Magnetizing inductors Lm1 and Lm2 as well as leakage inductors Lk1 and Lk2 are linearly charged by the input voltage source Vin as shown in figure 2. B. Mode II Fig. 4 Mode III At t = t2,as shown in figure 4, diode D2 automatically switches OFF because the total energy of leakage inductor Lk2 has been completely released to the output filter capacitor C1. Magnetizing inductor Lm2 transfers energy to the secondary side charging the output filter capacitor C3 via diode D4 until time t3. D. Mode IV Fig. 3 Mode II At t = t1, as shown in figure 3, the power switch S2 is switched OFF, thereby turning ON diodes D2 and D4. The energy that magnetizing inductor Lm2 has stored is transferred to the secondary side charging the output filter capacitor Fig. 5 Mode IV At t = t3, the power switch S2 is turned ON and all the diodes are turned OFF. Now all the diodes are reversed-biased and the Magnetizing inductors Lm1 and Lm2 as well as leakage inductors Lk1 and Lk2 are linearly charged by the ISSN: 2231-5381 http://www.ijettjournal.org Page 30
input voltage source Vin which is shown in figure 5. E. Mode V secondary side and it charges the output filter capacitor C2 through the diode D3 until t0. III. DESIGN PROPOSED CONVERTER Fig. 6 Mode V At t = t4, as shown in figure 6, the power switch S1 is turned OFF, therefore diodes D1 and D3 are turned ON. Now the energy stored in the magnetizing inductor Lm1 is transferred to the secondary side and it charges the output filter capacitor C2. The input voltage source and the energy stored in the magnetizing inductor Lm1 is completely released to the voltage-lift capacitor Cb through the diode D1, which supplies extra energy to Cb. F. Mode VI Fig.8 Control Strategy for the proposed converter The step up interleaved converter which introduced is also suitable as step up and high power conversion of the PV system, and the other step up interleaved converter introduced in, which is an asymmetrical interleaved structure as proposed converter is favourable for dc micro grid applications. In control strategy, the proposed converter is controlled by the microchip dspic30f4011 as shown in Fig.8, PV module and battery set are the main input power sources as shown, which can be seen as an equivalent voltage source for the proposed converter, and the MPPT algorithm which is employed by referring IV. SIMULINK BLOCK DIAGRAM Fig. 7 Mode VI At t = t5, as shown in figure 7, the diode D1 is automatically turns OFF because the entire energy stored in the leakage inductor Lk1 is totally released to voltage-lift capacitor Cb. Now the magnetizing inductor Lm1 transfers energy to the Fig. 9 Step up converter ISSN: 2231-5381 http://www.ijettjournal.org Page 31
Fig. 14 Vgs1, Vgs2, Id3, Id4 Fig. 10 PV model Fig. 15 Iin, Ilk Fig. 11 MPPT model Fig. 16 Vcb, Vc1, Vc2, Vc3 The output voltage of step up converter is the sum of all the voltages across the capacitors which are shown in figure number 16. So the output voltage is 380V of proposed step up converter. Fig. 12 Vgs1, Vgs2, ILK1, ILK2 Fig. 13 Vgs1, Vgs2, Id1, Id2 V. CONCLUSION This paper which is presented the topological principles, steady state analysis, and experimental results for a proposed step up converter. The proposed converter has been successfully implemented in an efficiently step up conversion without an extreme duty ratio and a number of turns ratios through the voltage multiplier module. The experimental results which indicate that leakage energy is recycled through capacitor Cb to the output terminal of the converter. The voltage stresses over the power switches are restricted and such are much lower than the output voltage (380 V). The switches which conducted to low voltage rated and low on state resistance MOSFET, which can be selected. Thus, the proposed converter which is suitable for photovoltaic power systems or other renewable energy applications that need high step-up high power energy conversion. ISSN: 2231-5381 http://www.ijettjournal.org Page 32
REFERENCES [1] Kuo-Ching Tseng, Chi-Chih Huang, and Wei-Yuan Shih, A High Step-Up Converter With a Voltage Multiplier Module for a Photovoltaic System, IEEE Transactions On Power Electronics, Vol. 28, No. 6, 0885-8993, June 2013 BIOGRAPHIES [2] Yushan Liu, BaomingGe, Haitham Abu-Rub, Fang Z. Peng, An Effective Control Method for Quasi-Z-Source Cascade Multilevel Inverter-Based Grid-Tie Single-Phase Photovoltaic Power System, IEEE Transactions On Industrial Informatics, Vol. 10, No. 1, 1551-3203, February 2014 [3] Tzuen-Lih Chern, Ping-Lung Pan, Yu-Lun Chern, Wei- Ting Chern, Whei-Min Lin, Chih-Chiang Cheng, Jyh- Horng Chou, Long-Chen Chen, Excitation Synchronous Wind Power Generators With Maximum Power Tracking Scheme, IEEE TRANSACTIONS ON SUSTAINABLE ENERGY, 1949-3029,2014 IEEE. [4] Pablo Acunna, Luis Moran, Marco Rivera, Juan Dixon, Jose Rodriguez, Improved Active Power Filter Performance for Renewable Power Generation Systems, IEEE Transactions On Power Electronics, Vol. 29, No. 2, 0885-8993, February 2014. Mr. Bhushan S. Chaudhari received the B.E. Electrical from Government College of Engineering, Jalgaon, in 2013, and pursing M.E. from S.S.B.T. s College Of Engineering and Technology, Jalgaon. He has published one paper in international journal. [5] Michael M. C. Merlin, Tim C. Green, Paul D. Mitcheson, David R. Trainer, Roger Critchley, Will Crookes, and Fainan Hassan, The Alternate Arm Converter: A New Hybrid Multilevel Converter With DC-Fault Blocking Capability, IEEE Transactions On Power Delivery, Vol. 29, No. 1, 0885-8977, February 2014. [6] Chung-Ming Young, Ming-Hui Chen, Tsun An Chang, Chun-Cho Ko, Kuo Kuang Jen, Cascade Cockcroft Walton Voltage Multiplier Applied to Transformerless High Step-Up DC DC Converter, IEEE Transactions On Industrial Electronics, Vol. 60, No. 2, 0278-0046, February 2013. [7] M.A. Abdullah, A.H.M. Yatim, C.W. Tan, A.S. Samosir, Control of a Bidirectional Converter to Interface Ultra capacitor with Renewable Energy Sources, IEEE Transactions, 978-1-4673-4569-9/13, 2013 IEEE. [8] Daniel Montesinos-Miracle, Miquel Massot-Campos, Joan Bergas-Jan e, Samuel Galceran-Arellano, and Alfred Rufer, Design and Control of a Modular Multilevel DC/DC Converter for Regenerative Applications, IEEE Transactions On Power Electronics, Vol. 28, No. 8, 0885-8993, August 2013. M. Mujtahid Ansari received his B.E.( Electrical Engg) and M.E.(Electrical Power System) from the S.G.B.University, Amravati, India in year 1996 and 2009 respectively. He is member of IE, ISTE and IACSIT. He has joined SSBT s College of Engineering and Technology, Jalgaon in the year 2000 where he is working as Assistant Professor in Electrical Engineering Department. He has published six papers in international journal and one text book. He was chairman Board of studies in Electrical Engineering and Instrumentation Engineering under the faculty of Engineering and Technology, North Maharashtra University, Jalgaon (MS) India. [9] K. I. Hwu, C. F. Chuang, W. C. Tu, High Voltage- Boosting Converters Based on Bootstrap Capacitors and Boost Inductors, IEEE Transactions On Industrial Electronics, Vol. 60, No. 6, 0278-0046, June 2013. [10] Qin Lei, Fang Zheng Peng, Space Vector Pulse width Amplitude Modulation for a Buck Boost Voltage / Current Source Inverter, IEEE Transactions On Power Electronics, Vol. 29, No. 1, 0885-8993, January 2014. Nilesh S. Mahajan had completed his M. E. in Electrical Power Systems from Government College of Engineering, Aurangabad. He is working as an Assistant Professor in the Department of Electrical Engineering in SSBT s College of Engineering & Technology, Bambhori, Jalgaon. He has published three papers in international journal. ISSN: 2231-5381 http://www.ijettjournal.org Page 33