IMPROVEMENT OF POWER CONVERSION EFFICIENCY OF A DC - DC ... · based on the integration of a buck PFC and a tapped buck DC/DC converter, is presented in this paper. Besides the high

IMPROVEMENT OF POWERCONVERSION EFFICIENCY OF A

DC - DC BUCK BOOST CONVERTERWITH SNUBBER CIRCUIT

Dr.R.SANKARGANESH1, S.Kannan2,K.KARTHIKEYAN3, 1Associate Professor

2Assistant Professor, 3PG Scholar1,3Department of Electrical and Electronics Engineering

2Department of Electronics and Communication Engineering1,2,3,4,5Vinayaka Mission’s Kirupananda Variyar

Engineering College Vinayaka Mission’sResearch Foundation

(Deemed to be University)Salem-636308, Tamilnadu, India

August 2, 2018

Abstract

DC/DC converters has major significance in the renew-able DC grid-connected control applications as a result ofthe low voltage of PV arrays and fuel cells. To connect themto the grid, the voltage level has to be adjusted accordingto the electrical standards in the countries. DC-DC con-verters are electronic devices which are used to change DCpower effectively starting with one voltage level then ontothe next. This paper gives the writing overview on differentsorts of converters used to get high voltage pick up in man-ageable vitality systems, for example, photovoltaic systems,fuel systems, and dc-dc protection system by using a snub-ber circuit. An un-polarized snubber circuit is used when a

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International Journal of Pure and Applied MathematicsVolume 120 No. 6 2018, 9999-10014ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

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pair of switching devices is used in anti-parallel which willprotect dc converter against leakage current.

Key Words: - DC Source, Bi-Directional DC-DC Con-verter, LC Filter, Snubber

1 Introduction

The bidirectional dc-dc converter along with energy storage hasbecome a promising option for many power related systems, in-cluding hybrid vehicle, fuel cell vehicle, renewable energy systemand so forth. It diminishes the cost and enhances efficiency, aswell as enhances the performance of the system. In the electric ve-hicle applications, an auxiliary Energy storage battery absorbs theregenerated energy fed back by the electric machine. Also, the bidi-rectional dc-dc converter is also required to draw power from theextra battery to boost the high-voltage bus during vehicle start, ac-celerate and hill climbing. With its capacity to switch the directionof the

current flow, and in this way control, the bidirectional dc-dcConverters are by and large progressively used to accomplish con-trol exchange between two dc control sources in either direction.In renewable energy applications, the multiple-input bidirectionaldc-dc converter can be used to combine different types of energysources. A fuel cell based system for domestic applications. Themulti-input bidirectional dc-dc converter is the core that intercon-nects power sources and storage elements and manages the power.This bidirectional dc-dc converter features galvanic isolation be-tween the load and the fuel cell, two-way power flow, the capabilityto match different voltage levels, fast response to the transient loaddemand, etc. As of late, clean vitality assets, for example, photo-voltaic exhibits and wind turbines have been misused for creatinginexhaustible electric power age systems. The bidirectional dc-dcconverter is frequently used to exchange the solar energy vitality tothe capacitive vitality source amid the sunny time, while to conveyvitality to the load when the dc transport voltage is low. A photo-voltaic power system with the bidirectional converter is shown in.The bidirectional dc-dc converter is regulated by the solar arrayphotovoltaic level, thus to maintain a stable load bus voltage andmake full use of the solar array and the storage battery. In this

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dissertation, a background description and review of the state-of-the-art bi-directional dc-dc converters are presented first to definethis work and its novelty. Then, the challenges will be identified re-lated to the design and control issues in the present non-disengagedbidirectional dc-dc control converter. The enhanced system is pro-posed with the upsides of high productivity, straightforward circuit,and minimal effort.

1.1 QUASI-RESONANT PASSIVE SNUBBER

2 LITERATURE REVIEW

A single stage offline power supply for LED lighting applications,based on the integration of a buck PFC and a tapped buck DC/DCconverter, is presented in this paper. Besides the high step-downcapability and the output current regulation, the proposed topol-ogy effectively provides power factor correction, to comply with theharmonic injection and energy saving standards EN 61000-3-2 andEnergy Star. The low BUS voltage level, resulting from the use ofan input step-down PFC stage, actually allows the use of film tech-nology capacitors, instead of short lifetime electrolytic capacitors,to filter the BUS voltage and reduce the LED current ripple com-ponent at twice the line frequency. Thanks to the high reliability,the simple structure, the excellent line side spectral performanceand the low component count, the proposed topology effectivelyresults to be very suitable for medium power solid state lightingapplications, as in the case of LED down-lighting. The issues re-lated to the operation of the presented solution and its design op-timization will be carefully discussed. A prototype of the proposedAC/DC converter has been built and tested. The primary experi-mental results will be described. In recent years LED lighting hasincreasingly attracted researchers attention in some different fieldsof application. In particular, as concerns, offline solid-state light-ing, LED lamps can be fed directly from the mains, through the useof switched mode power supplies. The actual configuration of suchpower converters depends on the typical requirements of the targetapplication, namely: the constraints limiting ballast cost and vol-ume, the power level of the LED load, the features of the lightingfixture, etc. However, despite the specific characteristics of each

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possible scenario, there are at least three main issues that have tobe always addressed when dealing with LED ballasts, i.e., circuitcomplexity, step-down capability, and line side converter spectralperformance. As concerns, this last aspect, the primary referencefor the European market is given by the EN 61000- 3-2 harmonicstandard. However, in recent years, also energy quality and effi-ciency standards, such as Energy Star and allied indications, beganto be taken into account, actually calling for improved power fac-tor and efficiency levels. Then, as regards the second previouslymentioned issue, the needed converter step-down capability canbe effectively guaranteed through some different isolated or non-isolated buck or buck-boost topologies. The step-down ratio thatis required will depend on both input line voltage characteristics(i.e., RMS value and relative tolerance) and load specifications (i.e.,kind, number and arrangement of LED devices). Finally, as con-cerns ballast topology, the actual goal is that of minimizing circuitcomplexity, to increase power density, improve conversion efficiencyand reduce costs. In this perspective, the use of a complex multi-ple stage configurations, as proposed, does not seem to be a goodoption, for medium power lighting applications such as LED down-lighting. On the other hand, however, also a conventional singlestage topology could be unsuitable. Despite its simplicity, indeed,this very cost-effective and compact configuration suffers the con-siderable variability of the operating conditions, which significantlycomplicates the optimization of converter design. As a matter offact, for the application under study, the most favorable solution toguarantee optimal converter design and high performance regard-ing both reliability and line side behavior, would be a two-stageconfiguration. However, being compactness, high power density,and low-cost applicable requirements, a suitable trade-off could bethe use of an integrated arrangement. Such a solution is based onthe combination of two different power conversion stages sharingthe same main controlled switch. This gives the possibility to re-tain most of the benefits deriving from the flexibility of a two-stageconfiguration while saving one active switch and the whole relateddriving and control circuitry. For this reason,as of late, a few novelconverter topologies have been proposed in the literature, in viewof blending converters by sharing the main switch. In particular, asconcerns the considered application, since the purpose is to get a

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simple, very reliable and low-cost power supply, capable of provid-ing power factor correction, to comply with the harmonic injectionand energy saving standards, the best solution appears to be theintegration of two step-down stages.

3 PROPOSED ARCHITECTURE

• This paper proposes interleaved bi-directional dc-dc converterswith a single-capacitor snubber to smooth out switch turn-off tran-sition.• The single-capacitor snubber is used to limit the rising rate of thedrain-source voltage of the metal-oxide-semiconductor-field-effecttransistor (MOSFET) switch in the converters to reduce turn-offloss.• Also, the converters are operated at the boundary of continu-ous and discontinuous conduction modes (CCM), (DCM) to reduceturn-on loss, and in an interleaving fashion to reduce output cur-rent ripple.• As compared with the counterparts of conventional convertertopologies, the proposed converters have the merits of less com-ponent count, higher efficiency over a certain load range, smallersize, and they are easier to implement. Hardware measurementsobtained from experimental prototypes have verified these merits.

3.1 BLOCKDIAGRAM FOR THE PROPOSEDSYSTEM

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Figure 1: Block Diagram for the Proposed Bi-Directional DC-DCConverter using Snubber Circuit

3.2 BLOCK DIAGRAM EXPLANATION

•Direct current (DC) is the unidirectional stream of electric charge.• A DC-to-DC converter is an electronic circuit or electromechani-cal device that changes over a source of direct present (DC) startingwith one voltage level then onto the next.•The inverter is an electronic device or circuitry that changes directcurrent (DC) to alternating current (AC)•A snubber is a device used to suppress a phenomenon such as volt-age transients in electrical systems.•Electronic channels are circuits which perform signal handling ca-pacities, particularly to expel undesirable recurrence segments fromthe signal.

3.3 BI-DIRECTIONAL DC TODC CONVERTER

Bidirectional DC-DC converters are used in applications where two-way power flow may be required. In hybrid electric vehicles (HEVs)and electric vehicles (EVs), these bidirectional converters charge alow voltage (12 V) battery during normal operation (buck mode)and charge or assist the high-voltage (400 V/600 V) battery orbus in emergency situations like when a high-voltage battery hasdischarged to a deficient energy or capacity level (boost mode). Atypical system consists of a full-bridge power stage on the high-voltage (HV) side, which is isolated from a full-bridge or a current-fed push-pull stage on the low voltage (LV) side.

3.4 BUCK MODE

A PSFB converter consists of four power electronic switches (likeMOSFETs or IGBTs) that form a full bridge on the primary side ofthe isolation transformer and diode rectifiers or MOSFET switchesfor synchronous rectification (SR) on the secondary side. Thistopology lets all the switching devices to switch with zero-voltage

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switching (ZVS), resulting in lower switching losses and an effi-cient converter. For such an isolated topology, signal rectificationis required on the secondary side. For systems with the low out-put voltage and high-output current ratings, implementing syn-chronous rectification achieves the best performance by avoidingdiode rectification losses. In this work, synchronous rectification isperformed on the secondary side with various switching schemes toattain optimum performance under varying load conditions. ThePWM switching signals for leg Q2Q3 of the full bridge are phase-shifted concerning those for leg Q1Q4. The amount of this stagemove chooses the measure of cover between slanting switches, whichdetermines the amount of energy transferred. D5 and D6 providediode rectification on the secondary, while Lo and Co form the out-put filter. Inductor LR assists the transformer leakage inductancefor resonance operation with MOSFET capacitance and facilitateszero voltage switching (ZVS). Provides the switching waveforms forthe system.

Figure 2: Buck Mode Power Stage

3.5 BOOST MODE

The synchronous rectifier switches are the push-pull switches inboost mode. The buck mode output inductor acts as a currentsource in this mode letting this topology work as a current-fed push-pull converter. Full-bridge switches on the HV side may be keptoff and their body diodes used for rectification. The full-bridgeswitches are used for active correction in the boost mode. Thepush-pull switches are driven with PWM signals with greater than50% duty cycles that are 180 degrees out of phase with each other.

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Figure 3: Boost Mode Power Stage

3.6 SNUBBER

Snubber Circuits Protection of switching devices and circuits: Switch-ing devices and circuit components may fail due to the followingreasons.1. Overheating thermal failure2. over current3. Overvoltage usually happens during turn-off4. Excessive di/dt5. Excessive dv/dt6. Switching loss excessive switching loss is a major contributingfactor to overheating. Power electronic circuits and their exchang-ing devices and parts can be protected from over current by settingwires at reasonable areas. Heat sinks, blades, and fans are utilizedto remove the overabundance warm from exchanging devices anddifferent segments. Snubber circuits are required to constrain dtdi, dt dv, and overvoltage amid turn-on and turn-off. Some typi-cal snubber circuits are described below. RC Snubber Circuits RCsnubber circuits are typically connected across a switching deviceto limit the dt dv. An RC snubber circuit can be polarized or un-polarized. A forward-polarized RC snubber circuit shown in Figure1 is appropriate when a thyristor or a transistor is connected withan anti-parallel diode. R limits the forward dt dv and R1 limits thedischarge current of the capacitor when Q1 is turned on.

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Figure 4: Snubber circuit

3.7 INVERTER

An inverter converts the DC voltage to an AC voltage. In mostcases, the input DC voltage is usually lower while the output ACis equal to the grid supply voltage of either 120 volts, or 240 Voltsdepending on the country. The inverter may be built as stan-dalone equipment for applications such as solar power, or to workas backup power supply from batteries which are charged indepen-dently. The other arrangement is the point at which it is a pieceof a more huge circuit, for example, a power supply unit, or anUPS. For this situation, the inverter input DC is from the correctedmains AC in the PSU, while from either the amended AC in the inthe UPS when there is control, and from the batteries at whateverpoint there is a power disappointment. There are distinctive sortsof inverters in view of the state of the exchanging waveform. Thesehave different circuit configurations, efficiencies, advantages, anddisadvantages. An inverter provides an ac voltage from dc powersources and is useful in power electronics and electrical equipmentrated at the ac mains voltage. Also, they are widely used in theswitched mode power supplies inverting stages. The circuits areclassified according to the switching technology and switch type,the waveform, the frequency, and output waveform.

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Figure 5: Inverter

3.8 FILTER

It is some of the time alluring to have circuits prepared to do specif-ically sifting one recurrence or scope of frequencies out of a blendof various wavelengths in a circuit. A circuit designed to performthis frequency selection is called a filter circuit, or just a filter. Afrequent need for filter circuits is in high-performance stereo sys-tems, where specific ranges of audio frequencies should be openedup or smothered for best stable quality and power effectiveness. Youmight be acquainted with equalizers, which permit the amplitudesof a few recurrence reaches to be acclimated to suit the audience’staste and acoustic properties of the listening territory. You maylikewise be acquainted with hybrid systems, which square particu-lar scopes of frequencies from achieving speakers. A tweeter (high-frequency speaker) is inefficient at imitating low-frequency signals,for example, drum beats, so a hybrid circuit is associated betweenthe tweeter and the stereo’s yield terminals to square low-recurrencesignals, just passing high-recurrence signs to the speaker’s associa-tion terminals. This gives better sound framework effectiveness andtherefore better execution. The two equalizers and hybrid systemsare cases of channels, intended to achieve sifting of specific frequen-cies. Another practical application of filter circuits is in the ”condi-tioning” of non-sinusoidal voltage waveform in power circuits. Someelectronic devises are sensitive to the nearness of harmonics in thepower supply voltage, thus require power conditioning for properactivity. In the event that a contorted sine-wave voltage carries onlike a progression of symphonious waveforms added to the majorrecurrence, at that point it ought to be conceivable to build a chan-nel circuit that lone enables the essential waveform recurrence togo through, blocking all (higher-recurrence) music.

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Figure 6: Filter

3.9 LOAD

The device which takes electrical vitality is known as the electricload. At the end of the day, the electrical load is a device thatdevours electrical power as the current and changes it into differ-ent structures like heat, light, work, and so on. The electrical loadmight be resistive, inductive, capacitive or some mix between them.The term stack is utilized as a part of the quantity of ways. Theresistive load discourages the flow of electrical vitality in the circuitand changes over it into thermal vitality, because of which the vi-tality dropout happens in the circuit. The light and the heater arethe cases of the resistive load. The resistive loads take control insuch a path in this way, to the point that the current and the volt-age wave stay in a similar stage. In this manner the power factorof the resistive load stays in solidarity.

4 CIRCUIT DIAGRAM

Figure 7: circuit diagram for the proposed system

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4.1 CIRCUIT DESCRIPTION

The circuit describes that varies the Dc power and operating loadfrequently. The +12v DC supply is connected to the DC-DC con-verter which improves the DC power with a protected snubbercircuit. The converter will improve the voltage up to double theamount of battery source (12-24) v DC. The inverter that converts(24DC-24AC) voltage. Finally, the inverted voltage will be steppedup in single-phase voltage (0-230) v. which drives an AC load withmodified to accessible load.

5 RESULT AND DISCUSSION

Figure 8: Hardware Model for the Proposed Bi-DirectionalConverter Circuit

5.1 HARDWARE OUTPUT

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5.2 ADVANTAGES

• High efficiency• Low switching losses• The non-linear load is implemented in real time application• The capacitor will improve overall system

5.3 APPLICATIONS

• Battery Charging• Dc Motor Control• Automotive Applications• Aircraft Applications

6 CONCLUSION

The bidirectional current flow control naturally has smoothly modetransition because of the unified power stage model and the adoptedunified controller, but for all the other mode transitions a partic-ular control scheme is needed to develop and further investigated.The other mode of transitions include a transition between sourceand load have some complication while leakage is affected .so thatsnubber control is implemented transition between voltage modebattery charging and bus system voltage mode is discharging, andtransition between current mode battery discharging and voltagemode releasing d in the for protection purpose.

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Documents

IMPROVEMENT OF POWER CONVERSION EFFICIENCY OF A DC - DC ... · based on the integration of a buck PFC and a tapped buck DC/DC converter, is presented in this paper. Besides the high