IRJET- Design and Implementation of Single Switch Sepic Converter for Supplying LED Driver Circuit with PFC Correction and the Automation System
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This document describes the design and implementation of a single switch SEPIC converter for an LED driver circuit with power factor correction and an automation system. The system uses a boost PFC converter operating in discontinuous mode to achieve a high power factor. A SEPIC converter is then used to supply a continuous current to the LED driver circuit. A snubber circuit clamps peak voltages and recycles leakage inductor energy. Experimental results showed the system could supply 48V and 2A to the LED load while achieving power factor correction and high efficiency. The system also includes an automation feature to power emergency lamps during a power failure using energy stored in a battery.
IRJET- Design and Implementation of Single Switch Sepic Converter for Supplying LED Driver Circuit with PFC Correction and the Automation System
- 1. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 03 | Mar 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1728 DESIGN AND IMPLEMENTATION OF SINGLE SWITCH SEPIC CONVERTER FOR SUPPLYING LED DRIVER CIRCUIT WITH PFC CORRECTION AND THE AUTOMATION SYSTEM R. Sathiya Priya1, G. Padhmini2, E. Tamilselvan3, K. Durgadevi4 1,2,3UG Student, Department of Electrical and Electronics Engineering, Valliammai Engineering college, Tamil Nadu, India. 4Assistant Professor, Department of Electrical and Electronics Engineering,Valliammai Engineering college, Tamil Nadu, India. ---------------------------------------------------------------------***---------------------------------------------------------------------- Abstract - The single switch led driver based on boost PFC converter and SEPIC converter for powerfactorcorrectionand automation system is proposed. In this proposed system , to obtain high power factor the step up converter should operate in discontinuous mode and SEPIC converter can be used to increase the life time of LED driver. Snubber circuit was designed to convert from peak voltage into low voltage and leakage inductor energy can be reclaimed . DC bus capacitor is used as low voltage capacitor where input should be directly propotional to output power. During power failure ,the emergency lamp can be designed for automation system. Thus the proposed LED system can be helpful to provide high efficiency and high power factor. The experimental working prototype can be verified by output of 48V and 2A . Keywords: SEPIC converter ,LED driver, Snubber circuit, Boost power factor converter and automation system. 1. INTRODUCTION Recently now a days, LED(light emitting-diode) plays a vital role in Lighting applications.LED have many advantages compared to conventional lamps.LED havemanyadvantages such as power consumption is low life time may be longer(50000 hours),high efficiency and provide environment safety. For operation of LED , SEPIC converterscanbeusedtoobtain high productivity, cheaper and weightless. A high power factor can be achieved with the help of power factor correction circuit (PFC circuit) for an AC input voltage .By using a snubber circuit, the current harmonics can be reduced and limits the voltage required for the circuit. In each stage LED drivers have double switches and double control circuits which are larger size and expensive.Toavoid this problem, a single stage led driver is used, which has single switch forboth thestages .A high pf can be obtainedby using a boost PFC circuit. In this paper , a single stage DC-DC LED driver based on boost-SEPIC PFC converterwithlosslesssnubberisproposed The boost PFC can be operated in Discontinuous conduction mode(DCM) for getting high power factor. For light load conditions DCM is preferred. A snubber circuit is used for clamping the peakvoltageintolowvoltagerequiredforSEPIC converter. The SEPICconverter is used forcontinuoussupplyofcurrent without any interruption. Thus proposed LED driver can get more productivity and high pf. Thus, the life time of the LED driver depends upon the hours of usage of power. If we utilize 12 hours a day, the life time can be 11 years and using 8 hours a day, the life time can be 17 years .Thus, the block diagram can be explained below. 2.BLOCK DIAGRAM OF PROPOSED AREA Figure.1 Block Diagram The AC input is passed to rectifier. The rectifier modifies AC into DC. Inputvoltagecontainsactiveandreactivepower.The reactive power should be lessthan or equal to 0.9.The power factor is corrected by using the boost PFC circuit. The PWM signals are controlled by using the microcontroller. The output is fed to TLP 250 MOSFET driver circuit to maintain 12 V, which is given to snubber circuit .In snubber circuit the harmonics are eliminated for continuous supply of current required for SEPIC converter .The output of SEPIC converter is finally fed to LED driver circuit.
- 2. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 03 | Mar 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1729 3.WORKING OF SEPIC CONVERTER Figure.2 Working of Sepic Converter To increase the overall efficiency of the light emitting diode (LED) weemploy a DC-DC converter. TheDC-DCconverteris used forthe continuous supply of current andthevoltagecan be high or low ,it will modify the required voltage for the driver circuit. This DC-DC converter can be of any type as buck or boost or buck boost type. If the output voltage has to be increased, we use a boost converter else we require buck converter. Inspite of a LED driver we sometimes need to increase or reduce output voltage, hence buck boost converter can be used. But buck boost converter has certain disadvantages such as poor transient response, need of a filter in the input side, high peak current etc. Thus we use a SEPIC converter which can increase or reduce the output voltage of the LED system. The block diagram of a SEPIC converter shows that it employs two inductors L1 and L2, three capacitors Cin, C1 and C2, a switch S1, a diode D and a resistiveloadRwhichare connected in seriesand parallel. ThecapacitorCinisusedasa filter capacitor,C1ascouplingcapacitorandC2asdecoupling capacitor. CASE 1 : WHEN THE SWITCH S1 IS OPEN Figure.3 Circuit diagram when switchs1 open When the switch S1 is open, input voltage flows through inductors L1 and L2, capacitances Cin, C1 and C2, Diode D1 and load R. The capacitancesand inductances chargesatthis case. Voltage flows through inductor L1, capacitor C1, inductor L2, diode D1, capacitor C2 and load RL. This is the voltage path when the switchS1isopen.Thisswitchcanbeof any switching device, but in this case we use a MOSFET (Metal oxide Semiconducting Field Effect Transistor). The main aim of using this SEPIC converter is to increase or reduce the output voltage to achieve the desired output. This is done by adjusting the PWM signals which is fed to the switching device that is MOSFET. The output voltage of the SEPIC converter is boostedbyincreasingONtimeofthePWM signals fed to the converter. And the output voltage of this converter can be reduced by reducing the ON time and increasing the OFF time. CASE : 2 WHEN THE SWTICH S1 CLOSED Figure.4 Circuit when switch S1 is closed In this case, when the switch S1 is closed there exists two loops of operation, because the current flows through the low impedance path and hence it passes through loop1 which is indicated in green lines in the figure. Only the leakage current flows through the loop2 that is through capacitor C1, inductor L2, capacitorC2,diodeD1andload RL which is indicated in red lines. Only very less voltage passes through the load which is lesser than the input voltageofthe converter. Thus the operation of a SEPIC converter is being discussed. 4. AUTOMATION SYSTEM During the power failure, the energy stored in the battery is automatically delivers the power into the load. This acts as emergency lamp circuit. PNP Transistor is a switch, As long as the mains power is ON, the positive from the supply is maintained at the base of the transistor, keeping it switched OFF.Thispreventsthevoltage reaching from battery to LEDs.When the ac mains power is lost, the positive voltage at the transistor goes off, which makes the transistor biased though R1.This makes the voltage to pass from transistor reaching LED. 5.CIRCUIT DESCRIPTION The filter circuit consists of Lf and Cf. TheboostPFCcircuitis composed of the boost inductor Lb, the main switch S1, and the reverse-blocking diode Db(which blocks reversecurrent through the boost inductor for DCM operation). The DC-bus
- 3. International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 06 Issue: 03 | Mar 2019 www.irjet.net p-ISSN: 2395-0072 © 2019, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 1730 capacitor Cdc , output capacitor Co , output diode Do and a snubber circuit consists of C1,D1 and L1is included inDC-DC SEPIC circuit. To describe the parasitic component of circuit parts for theoretical analysis, during switching period Vin can be considered as constant value. The output for S1 is fed by capacitor CS1.The magnetizing inductor Lm is within the coupled inductor T1 and the turn ratio ofleakageinductorLk is n:1(n=Np/Ns).Hence, Lm is greater than Lk. Volt-second balance law states that , at the steady state the average inductor should be zero. The voltage across the C1 and Cdc should be equal to Vdc.The voltage through capacitances of C1, Cdc and C0 are considered to be constant. Figure.5 Circuit Diagram 6. RESULT Thus the experiment was verifiedfor48Vand2A.Thepower factor is corrected for continuous operation of LED Driver circuit and high efficiency is achieved. 7. CONCLUSION A single-switch DC-DC LED driver based on a boost-SEPIC converter with a lossless snubber has been proposed. The boost PFC circuit can be operated in DCM mode to achieve high power factor. In DC-DC SEPIC circuit, the snubber circuit is used to clamp the peak voltage strikes and recycle the inductor leakage energy. A low voltage capacitorisaddedadditionallybecause the input power is directly connected from boost inductor to the output. Thus the total productivity is improved. The experiment is evaluated for an output current of 2A and output voltage of 48V. Figure.6 Prototype model 8. REFERENCES 1) N. Chen and H.S.-H. Chung, “An LED lamp driver compatible with low and high frequency sources,” IEEE Trans. Power. Electron., vol. 28, no.5, pp. 2551-2568, May2013. 2) J. Choi, H.-S. Han and K.Lee, “A current- sourced LED driver compatible with fluorescent lamp ballasts,” IEEE Trans. Power. Electron., vol. 30, no.8, pp. 4455- 4466, Aug 2015. 3) S. Almeida, H. A. C. Braga, M. A.D. Costa, and J. M. Alonso,” Offline soft-switched LED driver based on an integrated bridgeless boost-asymmetrical half- bridge converter,”IEEE Trans. Ind. Appl., vol. 51, no.1, pp.761- 769, Jan 2015. 4) Y.-C. Li and C.-L. Chen,” A novel single- stage high- power-factor AC-to-DC LED driving circui with leakage inductance energy recycling,” IEEE Trans. Ind. Electron., vol.59, no.2, pp.793-802, Feb.2012. 5) Y. Hu, L. Huber, and M. M. Jovanovic, ”Single- stage, universal-input AC/DC LED driver with current- controlled variable PFC boost inductor,” IEEE Trans. Power. Electron., vol. 27, no. 3, pp.1579- 1587, Mar.2012