GRD Journals Global Research and Development Journal for Engineering International Conference on Innovations in Engineering and Technology (ICIET) - 2016 July 2016 e-issn: 2455-5703 Design and Implementation of a Novel Transformer less DC to DC Converter for LED Display Application 1 T.Deepika Vinothini 2 R. Kiruthika 3 P. Padmadevi 4 P. Uma Devi 1,2,3,4 Student 1,2,3,4 Department of Electrical and Electronics 1,2,3,4 Velammal College of Engineering Abstract This paper uses high frequency transformer less chopper with voltage boosting and low stress. The topology uses automatic current sharing capability and voltage summing at the output terminal by lower value of MOSFET, diodes. In addition to this proposed technology losses are reduced. Blocking capacitor introduces automatic current sharing in the circuit because of charge balance in the capacitor. The proposed topology provides voltage boosting with no extreme duty cycle. In relating to the existing proposed system voltage gain is proposed. Electrolytic capacitor used to reduce the current ripple.by having more current ripple will reduce the output port power in the circuit.incase if output diode stress greater than the output voltage efficiency of circuit reduces for high output voltage application. The reduction of voltage stress and voltage gain can be achieved using ultra high step-up convertor with addition to power factor correction by voltage doubler circuit. Keyword- non isolated, current ripple reduction, voltage boosting. low voltage stress, automatic current sharing system, power factor correction. I. INTRODUCTION Because of shortage of power generation renewable, non-renewable waste are used for power generation across the world. Due to lowering in system efficiency both buck and buck-boost converter reduces duty ratio to 1.However extreme duty cycle ratio not only induces voltage spikes but also introduces the conduction losses this induces severe diode reverse-recovery. Simple isolated structure adopted is dc-dc fly-back converter.with the help of DC-DC fly-back voltage boosting is achieved but this provides leakage inductance. Leakage inductance induces voltage stress to the active switches.some regeneration techniques has been proposed to reduce the voltage stress to achieve voltage boosting. Regeneration output will removes the stress of switch and recycle the leakage inductance of the circuit. Phase shifted full-bridge converter provides high voltage gain by changing turns ratio of transformer. But on other hand it introduces current ripple in the circuit in turn it degrades the output voltage and life of electrolytic capacitor. Electrolytic capacitor will reduces large ripple current. Another type of converters used is isolated current type converter the disadvantage of this converter it makes use of sensor or otherwise feedback controllers, by using all these devices for isolated current type converter provides high voltage gain and low active switch stress.for reducing the cost of the device in the same way to improve efficiency non-isolated dc-dc converter is adopted in system. Conventional switched capacitor increases output efficiency and voltage conversion ratio. But sometimes it suffers from large voltage transient s.on other hand if interleaved voltage doubler are used for power factor correction In simultaneously with automatic current sharing capability. By this technique the voltage gain obtained is not too high in turn it reduces the diode stress. Coupled inductor converters can be used for voltage boosting in a circuit.another advantage of using coupled inductor based converter provides control of voltage at the output terminal by changing the turns ratio of the inductor employed in the circuit.however it produces current ripples. The proposed paper uses two boost converter techniques for achieving voltage boosting and current sharing capability with extreme duty cycle. 312
II. BLOCK DIAGRAM Fig. 1: Block diagram of proposed converter A. DC Input Sources This proposed converter can be used in transformer for voltage conversion process of 230 voltage to 12 voltage. This voltage convert the pure DC in the rectifier and filter circuit. The converted voltage should be regulated using regulator IC in 7812.The regulated voltage given to the DC to DC converter. B. Driver Circuit Another transformer used to give the 12 voltage to the regulator circuit. The regulator circuit gives two types of supply voltage. One is 12 voltage this is given to the driver circuit. IR2110 Driver MOSFET is will give input to the main circuit. The voltage will be boosted up because of usage of the mosfet.this will turn on the 10 voltage circuit. C. Microcontroller Circuit We are using ATMEGA16A Micro controller IC. This is 40 pin IC package.8pin inputs is given. The topology uses two input. They are given to the driver circuit. Thus output 8pins were connected to LCD display. High performance and programming lock are used for software security. Six sleeping modes are presented. This is operated in only 5 voltage. D. DC to DC Converter We are using two IRF840 mosfet for input purpose with Nanoseconds switching speed and high input impedence.these pulses are given to the mosfet. E. Load We can use up to 120 voltage in load. The potentiometer used to vary the input voltage and output is varied depends upon the input voltage. III. OPERATION Fig. 2: Equivalent circuit of proposed converter 313
The proposed converter uses two switches by using two switches in place of four switches the stress of diode is increased to the maximum.the main objective of the converter is to reduce the stress of both the switches without reduction in the voltage output. This circuit makes use of four diode. So that it can be connected as buk and buk- boost converter. And two diodes across the switches. A. Mode 1 During this mode of operation both switches(s1,s2) are turned on at the same time all diodes remains in off state condition.so the stress across the diode D1a,D2a are obtained as Vca and Vcb.the diode voltage across the diode D1b,D2b are the part of the voltage from Vc2,Vcb and vc1,vcb respectively. Capacitor energies are fed to load system. Fig. 3: This diagram is for mode 1 & mode 3 B. Mode 2 During this mode of operation switch (S1)is on & another switch S2-off.correspondingly diode D2a,D2b are turned on. During the previous mode of operation inductor L2 and capacitor Ca stores energy this energy is used by load and capacitor C1. Fig. 4: This diagram shows mode 2 operation C. Mode 3 This mode is Similar to mode 1. Inductor L1 and L2 stores energy.voltage in D1a, D2a is same as voltage Vca and Vcb respectively. Voltage in D1, D2 is obtained as part of voltage of Vc2, Vcb and Vc1,Vca respectively. Then this energy is fed by the Capacitor to the load. D. Mode 4 This mode is similar to mode 2.But the switch S2 is turned on and Switch S2 is turned off. Diode D1a, D1balso turned on Energy stored in inductor L1 is energy supplied from capacitor (Cb) this fed power to C2 & load. During that period of conduction energy stored in inductor L1 is fed from Ca.capacitor Ca fed the power to Vc(Vcb+Vca). 314
Fig. 5: This diagram is meant for mode 4 IV. EXPECTED OUTCOME Voltage obtained at the output terminal is the boosted voltage though both buck & boost conversion can be achieved but boosting the voltage alone adopted. The must be seven times the input voltage at the output terminal. The circuit is made up for LED application voltage must be stepped down without using transformer this can be achieved by resistor load Noises can be introduced into the circuit.this noises are reduced in the circuit by capacitor connected across resistor load. V. CONCLUSION The topology uses automatic current sharing capability and voltage summing at the output terminal by lower value of MOSFET, diodes values to our requirement. So the output efficiency is improved to maximum level with reduced no of devices. System can also be used for steady state analysis. Electrostatic stress is consider high when two switches do the work of four switches.capacitor reduces the electrostatic stress of the switches also improves voltage turns ratio, system efficiency. Transformer less circuit reduces switching and conduction losses. So this proposed method is highly suitable for industrial application. The revised topology can be used for high starting torque devices, household application, and lift application and especially for trolley traction. REFERENCES [1] Jianwu Zeng, Student Member, An Isolated Multiport DC DC Converter for Simultaneous Power Management of Different Renewable Energy Sources IEEE, Wei Qiao, Senior Member, IEEE [2] Novel high step-up DC DC converter with coupled-inductor and voltage-doubling circuits, L. S. Yang, T. J. Liang, H. C. Lee, and J. F. Chen, IEEE Trans. Ind. Electron. 315
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