Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications

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1 ISSN (Print) : ISSN (Online) : Indian Journal of Science and Technology, Vol 10(37), DOI: /ijst/2017/v10i37/117553, October 2017 Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications P. Priya, G. Shabbeer Basha*, S. V. Sujith Niranjan and R. Seyezhai SSN College of Engineering, Kalavakkam , Tamil Nadu, India; gsb_basha@yahoo.co.in, sujithsv1996@gmail.com, ayushmati17@gmail.com, seyezhair@ssn.edu.in Abstract Objectives: To design and analyze a high gain converter namely Quadratic Boost Converter which acts as an interface with the solar Photovoltaic power generation. Methods: The design and testing of the Quadratic Boost Converter is done using MATLAB and SIMULINK. The performance parameters such as voltage gain, output voltage ripple and stress across the switches are computed. The losses in the converter are calculated and listed. The hardware prototype for the converter is developed to highlight the important features of the converter. Findings: Currently, solar Photovoltaic generation plays an important role to satisfy the energy demand and it provides numerous benefits such as it operates without pollution, no fuel is required and basically a clean energy source without polluting the environment. Application: A single PV cell produces a low output voltage and therefore a suitable interface circuit is required for DC applications. The Quadratic Boost Converter is best suited because of its high gain, reduced voltage and current stress with high efficiency without increasing the number of active switches compared to the conventional boost converter. Also the limitation of switching frequency and voltage gain is overcome in this proposed topology. Keywords: Efficiency, Losses, Photovoltaic, Quadratic Boost Converter, Ripples 1. Introduction Global warming and the depletion of fossil fuels are the major problems faced by every country in this world. These problems have threatening consequences. The world is on the verge of a larger calamity. These problems can be reduced by shifting the methods of generating power to a different method. The new growing field of generating energy is the renewable energy systems. There are numerous advantages associated with the renewable energy systems such as, they are environmental friendly. There are certain disadvantages too. Few of the majorly used renewable energy systems are the Photovoltaic (PV) panels and the fuel cell stacks. These systems do not emit any greenhouse gases and so they are non-polluting and can produce clean electricity for decades. To store the energy, batteries can be used. But the power that we procure from these resources has a lower output voltage and so a bank of batteries might be required. This will lead to *Author for correspondence

2 Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications extra space and weight and higher cost leading to impracticality issues. So an interface is used to step-up the voltage obtained from these systems. There are a lot of topologies that act as an interface. Such an interface is a Boost converter 1,2. Boost converter is a popular non-isolated power stage technology. Boost converters are used to step up an input voltage to some higher level required by the load. The boost converter has the advantage of storing energy in inductor and supplying it to the load at higher voltages. The input current for a boost converter is continuous or non-pulsating, because the input current is same as the inductor current. Small signal, transient performance, power dissipation and electromagnetic interference are some of the considerations taken while designing the converter circuit. But the conventional boost converter has certain drawbacks such as they are unable to switch faster; they are not suitable for high power conversion and also withstand high temperatures. Quadratic Boost Converter is a new topology which has certain advantages such as increasing the efficiency and voltage gain without increasing the number of switches used or the duty cycle. This converter injects less current ripple into the source and so the efficiency and the life span can be increased with that of the PV arrays 3,4. This paper presents the simulation analysis and the loss calculations for the designed converter along with simulation results of the closed loop system. This paper also shows the hardware prototype and its results for validation with the theoretical results. 2. Quadratic Boost Converter (QBC) The QBC shown in Figure 1 has a single switch in it and has two capacitors, three diodes, two inductors and a load resistance 5. Cascaded converters are those that combine converters back to back using additional switches. Quadratic Boost Converter is one such converter which does a similar functions but with only one switch. It has a higher voltage conversion ratio when compared to conventional boost converter. This increased gain makes this converter to be more suitable to be a part of the power system which integrates Photovoltaic systems and wind energy systems and in microgrid applications 6,7. Figure 1. Quadratic Boost Converter: Topology. 2 Indian Journal of Science and Technology

3 P. Priya, G. Shabbeer Basha, S. V. Sujith Niranjan and R. Seyezhai 2.1 Operation of QBC The circuit has two intervals of operation. From Figure 2, when the switch is turned on the diode D 2 is forward biased, whereas the diodes D 1 and D 3 are reverse biased. Currents are supplied to inductors L 1 and L 2 by VIN and capacitor C 1 respectively, while the capacitor C 2 is discharged by the load resistance R. As seen in Figure 3, when the switch is turned off, the diodes D 1 and D 3 are forward biased, whereas D 2 is reverse biased. The inductors L 1 and L 2 are charging C 1 and C 2 respectively. Thus both the intervals work one after the other. Figure 2. Quadratic Boost Converter: Topology when SW is turned on. Figure 3. Quadratic Boost Converter: Topology when SW is turned off. Indian Journal of Science and Technology 3

4 Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications 2.2 Design Values The circuit parameters for the simulation and hardware prototype were designed 8 and are listed in Table Simulation Results Figure 4 is the model of the converter. From Figure 5 we find that after the initial transients the output voltage in Table 1. Design values of QBC Parameters Input Vin Output Vo Frequency f Value 12 V V 100 khz Duty cycle D 50% L 1 C 1 L 2 C 2 Load R 60 uh 10 uf 240 uh 2.6 uf 30 ohm Figure 4. SIMULINK model of Quadratic Boost Converter. 4 Indian Journal of Science and Technology

5 P. Priya, G. Shabbeer Basha, S. V. Sujith Niranjan and R. Seyezhai Figure 5. Output voltage of Si Quadratic Boost Converter. Figure 6. Output voltage ripple of Si Quadratic Boost Converter. steady state has an average value of V and from Figure 6 we see that the voltage ripple is only Analysis of Si Quadratic Boost Converter This section provides the simulation results of comparison of the boost and Quadratic Boost Converter, both using silicon MOSFETs. The simulation results were obtained using MATLAB-SIMULINK simulation package. 4.1 Source Current Ripple vs. Duty Cycle The plot in Figure 7 compares the input current ripple of the Quadratic Boost Converter and conventional boost Indian Journal of Science and Technology 5

6 Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications Figure 7. Plot for current ripple vs. duty cycle. converter and is found to be very much less than that of the Boost converter and this is very much advantageous for the life span of both the source and the converter. 4.2 Load voltage ripple vs. Duty Cycle From the Table 2, we infer that the load voltage ripple of the Quadratic Boost Converter is comparatively less than that of the boost converter. Table 2. Load voltage ripple vs. duty cycle Duty cycle Boost converter Quadratic Boost Converter Indian Journal of Science and Technology

7 P. Priya, G. Shabbeer Basha, S. V. Sujith Niranjan and R. Seyezhai 4.3 Load Current Ripple vs. Duty Cycle From the Table 3, we infer that the load current ripple of Quadratic Boost Converter is comparatively less at lower duty cycles. 4.4 Gain vs. Duty Cycle From the Figure 8 we can infer that the Quadratic Boost Converter has a quadratic voltage conversion ratio unlike Boost converter which has less gain. Table 3. Load current ripple vs. duty cycle Duty cycle Boost converter Quadratic Boost Converter Figure 8. Plot for gain vs. duty cycle. Indian Journal of Science and Technology 7

8 Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications 5. Losses in the Quadratic Boost Converter There are various losses associated with the converters. Generally, most of the insignificant parameters are neglected. But for accurate measurements of the losses, the small losses which are neglected are considered along with the practical values The power losses in converter are due to the following parameters: Conduction loss of MOSFET. Turn on and turn off losses of MOSFET. Gate charge or Input capacitance loss. Output capacitance loss. Diode loss. Inductor loss. 5.1 Conduction Loss of MOSFET The conduction loss is mainly dependent on the onstate resistance of the MOSFET and that resistance is dependent on the junction temperature and the applied gate-source voltage (VGS). The power loss equation is given by: (4) 5.2 Turn on and Turn off Loss of MOSFET The switching losses associated with the MOSFET can be determined using the data from the datasheet of the MOSFET to be analyzed. (5) 5.3 Gate Charge or Input Capacitance Loss The gate charge loss depends on the value of the input capacitance of the MOSFET. The total gate charge or the value of the input capacitance is taken from the datasheet. 5.4 Output Capacitance Loss (6) The value of C oss is taken from the datasheet. This value is dependent on the drain voltage of the MOSFET. For better analysis, the maximum value is considered. (1) (2) 5.5 Diode Loss (7) The loss due to diode is dependent on the forward voltage of the diode. (3) (8) 8 Indian Journal of Science and Technology

9 P. Priya, G. Shabbeer Basha, S. V. Sujith Niranjan and R. Seyezhai (9) 5.7 Efficiency The Equation 13 is used to compute the Quadratic Boost Converter efficiency and the consolidated results are displayed in Table Inductor Loss (10) The inductor has a significant amount of loss parameter. The factors that contribute to this loss are the wire loss and the second is the core loss. The wire loss is a DC loss while the core loss is an AC loss. (11) (12) (13) 6. Simulation Results Closed Loop Operation Pulse width modulation is the technique employed for the operation of the converter in closed loop mode. A PI controller is used to minimize the error and bring the steady state error to zero. The reference voltage is set and the error value is obtained. PWM technique is enforced by comparing the output of the PI Controller with a triangular wave of the switching frequency thereby operating in the set voltage level 12,13 as shown in Figure 9. Table 4. Losses and efficiency Losses Value P (loss_rdson) W P (loss_trise_tfall) W P (loss_gatecharge) W P (loss_coss) W P (loss_diode) W P (loss_wire) W Efficiency 89.63% Indian Journal of Science and Technology 9

10 Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications Figure 9. Closed loop SIMULINK model of Quadratic Boost Converter. Figure 10. Output voltage of Quadratic Boost Converter (Closed loop). From the Figure 10, we can see that after the initial transient the voltage reaches a steady state value of 48 V which is the reference voltage that is set in the closed loop system. 10 Indian Journal of Science and Technology

11 P. Priya, G. Shabbeer Basha, S. V. Sujith Niranjan and R. Seyezhai 7. Hardware Experimental Results The Quadratic Boost Converter was designed and based on the design values the prototype was made. An IRFP460 MOSFET is used here as the switch. The inductors are 60 uh and 240 uh with 2A current rating. The optocoupler module used is TLP350 Driver board. For gate pulse, PIC16F877A microcontroller is used to generate pulse of 90 khz frequency. From the Figure 11, we find that the PV panel powered by halogen lamp is used as a source and by using a charge controller the input voltage is regulated to 12 V and is supplied to the converter. The output is checked across a resistive load and the output voltage of 44.4 V is observed. 8. Conclusion This paper has presented the simulation analysis and comparison of Quadratic Boost Converter with Boost converter wherein the source current ripple of Quadratic Boost Converter is found to be only Also the load voltage ripple is found to be comparatively less (0.0663). The losses are calculated and the conduction loss amount to W and the switching losses amount to W. The efficiency of the converter is found to be 89.63%. A hardware prototype for the same design was developed and the results were verified successfully. Further development of this converter can be done by implementing the same using wide band gap material switch like SiC MOSFET. Figure 11. Hardware prototype of QBC. Indian Journal of Science and Technology 11

12 Analysis and Experimentation of Quadratic Boost Converter for Photovoltaic Applications 9. References 1. Al-Saffar MA, Ismail EH, Sabzali AJ. High efficiency Quadratic Boost Converter. Applied Power Electronics Conference and Exposition (APEC); 2012 Feb. p Newlin DJS, Ramalakshmi R, Rajasekaran S. A performance comparison of interleaved boost converter and conventional boost converter for renewable energy application. International Conference on Green High Performance Computing; 2013 Jun, p Crossref. 3. Dhanasekaran R, Arun Prasath T. Performance comparison of solar power using Quadratic Boost Converter with coupled inductor. International Conference on Advanced Communication Control and Computing Technologies (ICACCCT); 2014 May. p Beena KH, Benny A. Analysis and implementation of Quadratic Boost Converter for Nanogrid applications. IJAREEIE Jul; 4(7): Tattiwong K, Bunlaksananusorn C. Analysis design and experimental verification of a Quadratic Boost Converter. TENCON, IEEE; 2014 Oct. p Navamani DJ, Veena ML, Lavanya A, Vijayakumar K. Efficiency comparison of Quadratic Boost DC-DC Converter in CCM and DCM. International Conference on Electronics and Communication Systems; 2015 Jun. p Crossref. 7. Choudhury TR, Nayak B. Comparison and analysis of cascaded and Quadratic Boost Converter. Power Communication and Information Technology Conference; 2015 Oct. p Crossref. 8. Priya P, Basha SG, Niranjan VSV, Seyezhai R. Investigation of Sic MOSFET based Quadratic Boost Converter for Photovoltaic Applications. IJPERA Oct; 1(3): Marsala G, Ragusa A. Power losses analysis and efficiency evaluation of high boost converters for PV and fuel cell applications. International Conference on Electric Utility Deregulation and Restructuring and Power Technologies; 2015 Nov. p Crossref. 10. Pawlak M, Radomski G, Kaplon A. Experimental verification of DC/DC Boost Converter calculation model considering conduction losses. Selected Problems of Electrical Engineering and Electronics (WZEE); 2015 Sep. p Hwang JH, Soh JH, Kim YR. Design procedure for minimizing conduction loss for ZCT PWM boost converter. Future Energy Electronics Conference (IFEEC); 2015 Nov. p Ghamrawi A, Gaubert JP, Mehdi D. New control strategy for a Quadratic Boost Converter used in solar energy system. Energy Conference (ENERGYCON); 2016 Apr. p Crossref. 13. Mitulkumar RD, Dave CK. Analysis of boost converter using PI control algorithms. International Journal of Engineering Trends and Technology. 2012; 3(2): Indian Journal of Science and Technology