implementation of zvs resonant converter with … · llc resonant converter with a center-tapped...

IMPLEMENTATION OF ZVSRESONANT CONVERTER WITH

SERIES-CONNECTEDTRANSFORMERS

R.Arun Kumar1 and V.Sivachidambaranathan2

1PG Scholar, EEE Department,Sathyabama University Chennai, India

[email protected], Professor, EEE Department,

Sathyabama University Chennai, Indiasivachidambaram [email protected]

January 3, 2018

Abstract

The series-resonant converter with series-connected trans-formers in order to realize Zero Voltage Switching (ZVS) forpower switches, Zero Current Switching (ZCS) for rectifierdiodes at full load, less transformer secondary winding witha full-wave rectifier, and load current sharing two series-resonant converters using the same switches are operatedwith interleaved half switching cycle. The secondary wind-ings of transformers are connected in series in order to en-sure that the primary side currents are balanced to shareload current. Thus the sizes of the transformer core andbobbin are reduced The full-wave diode rectifier is adoptedon the output side such that the voltage stress of the rectifierdiodes is equal to the output voltage, rather than being twotimes the output voltage as in a conventional center-tappedrectifier topology The proposed converter has the following

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International Journal of Pure and Applied MathematicsVolume 118 No. 16 2018, 1131-1148ISSN: 1311-8080 (printed version); ISSN: 1314-3395 (on-line version)url: http://www.ijpam.euSpecial Issue ijpam.eu

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advantages such as less switching losses, reduced electricaldynamic stresses The circuit has simulated using MATLABand the results are presented.

Key Words : Pv array, sepic converter, voltage sourceinverter, power conversion, , pwm technique.

1 INTRODUCTION

The efficiency requirements of the Environment Protection Agencyand Climate Saver Computing Initiative for modern power sup-ply units, soft-switching converters with high switching frequencyhave been proposed for the past 20 years. Pulse width modula-tion [1] and [2] and frequency modulation [3], [4] are generally usedto control the output voltage for different load conditions. Powerconverters featuring zero voltage switching (ZVS) characteristics[5][12] have been proposed to reduce switching losses of MOSFETs.However, the ZVS effect of these techniques is limited to specificinput voltage ranges or load conditions Thus, it is difficult to de-sign soft-switching converters with wide load ranges. For frequencymodulation, series-resonant converters and parallel resonant con-verters have been proposed in [3], [4] with high efficiency and lownoise However, the output voltage cannot be properly regulatedat no-load condition in a conventional series resonant converter.To solve this problem, parallel resonant converter [4] was devel-oped. The drawback of parallel resonant converters is that thecirculating energy reduces the high line or light load efficiency At-tention has been drawn to LLC series resonant converters due totheir advantages of high voltage gain, high conversion efficiency,and high power density [13][27]. Due to the resonant behavior,power switches can be turned on at ZVS If the operating switchingfrequency is lower than the series resonant frequency, the rectifierdiodes can be turned off at ZCS. As a result, verse recovery lossesfor the rectifier diodes are reduced diodes are reduced. This paperpresents a new series-resonant converter with two series transform-ers and a full-wave diode rectifier in order to achieve soft switchingfor all semiconductors with wide input voltage ranges and load con-ditions. Since the input impedance of the resonant tank is from aninductive load at the operating switching frequency, power switches

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can be turned on at ZVS. If the operating switching frequency islower than the series resonant frequency, rectifier diodes can beturned off at ZCS with wide input voltage ranges. Thus, switchinglosses of power switches and reverse recovery problem of the rec-tifier diodes can be reduced. Two series-resonant converters withphase shifted half switching frequency are used in order to lesseninput ripple current and to reduce the size of the magnetic coreand the current stress on the primary windings. The secondarywindings of two transformers are connected in series to balance theprimary currents and to share the input current. In a conventionalLLC resonant converter with a center-tapped rectifier, the voltagestress of the rectifier diodes is greater than two times the outputvoltage. If the output voltage is greater than 400 V, the minimumvoltage stress of the rectifier diodes is greater than 800 V. Full-wavediode rectifiers is used at the output side to decrease the diode volt-age stress. The voltage stress of the rectifier diodes is clamped tooutput voltage. Thus, full-wave diode rectifier is suitable for highoutput voltage applications, although there are two diode conduc-tion losses. Experiments based on a 1000-W prototype to verify theeffectiveness of the proposed converter are described

2 BLOCK DIAGRAM

In this project input voltage of DC source and high frequency flyback converter used to converter AC voltage .The isolation trans-former used to step up the voltage secondary side rectifier used toconverter the DC voltage C filter getting more ripple voltage .Themodified circuit using PI filter to reduced the ripple voltage thebock diagram shown in fig 2.1.

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Fig 2.1 fly back inverter

3 DESIGN OF CONVENTIONAL CON-

VERTER

The fig 3.0 shows the conventional method circuit diagram. C filteris used to simulate output load side and getting more ripple voltage.The input voltage shown in fig 3.1 and switching pulse for M1 & M2and M2 & Vds shown in fig 3.2 and fig 3.3 respectively. Transformerprimary and secondary voltage shown in fig 3.4 and fig 3.5. Outputvoltage shown in fig 3.6 and fig 3.7 shows output current wave form.Fig 3.8 shows the output ripple voltage of conventional circuit. Theinput voltage for the circuit 24v and output voltage is 43v. In thissystem high voltage ripple observed in output simulation results.

Fig 3.0 Circuit diagram for conventional method

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Fig 3.1 input voltage

Fig 3.2 Switching pulse for m1&m2

Fig 3.3 Switching pulse for m2&Vds

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Fig 3.4 Transformer primary voltage

Fig 3.5 Transformer secondery voltage

Fig 3.6 Output voltage

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Fig 3.7 Output current

Fig 3.8 Output ripple voltage (0.3v)

4 DESIGN OF THE PROPOSED CON-

VERTER

The proposed system circuit shown in fig 4.0. This circuit inputvoltage of 24v and output voltage of 48v. Compared with con-ventional circuit, proposed circuit has better voltage and reducedripple voltage. Fig 4.1 shown as input voltage of 24v. Switchingpulse for M1 & M2 and M2 & Vds shown in fig 4.2 and fig 4.3respectively. Transformer primary and secondary voltage shown infig 4.4 and fig 4.5. Output voltage shown in fig 4.6 and fig 4.8 showsoutput current wave form. Fig 4.7 shows the output ripple voltageof proposed circuit. In this system low ripple voltage observed inoutput simulation results when compared with conventional circuit.

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Fig 4.0 Proposed circuit diagram with Pi filter

Fig 4.1 Input voltage

Fig 4.2 Switching pulse for m1,m2

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Fig 4.3 Switching pulse for m2&Vds

Fig 4.4 Transformer primary voltage

Fig 4.5 Transformer secondary voltage

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Fig 4.6 Output voltage

Fig 4.7 Output ripple voltage (0.05v)

Fig 4.8 Output current

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Fig 4.9 output powers

5 EXPERIMENTAL RESULTS

Experiments based on a motor load shown in fig 5.0. This circuitinput voltage of 24v and output voltage of 48v. The Measured wave-forms of input voltage shown in fig 5.1 and the measured waveformof Motor speed and torque shown in fig 5.2 and fig 5.3 respectively.Table 1 shows the comparison of proposed with conventional cir-cuit parameters. Table 2 shows the comparison of output and inputpower for different load resistance (Ro) and table 3 shows the inputpower vs output power. From the fig 5.5 experiments describing theeffectiveness of the converter.

Fig 5.0 Motor load

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Fig 5.1 Input voltage

Fig 5.2 Motor speed

Fig 5.3 Torque

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Table-1

Table-2

Fig 5.4 Input power vs Output power

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Table -3

loadresistance(Ro)

conventionalefficiency

proposedcircuit

efficiency10 82 9415 84 9520 85.5 95.525 86 96

Fig 5.5 Efficency vs Load resistance

6 CONCLUSION

This paper compared to open loop conventional method and openloop proposed method the proposed system better high step upvoltage ratio and reduced ripple voltage the table-1 as shown thevariation of ripple voltage and the simulated to different load re-sistance used input power and output power also table-2 explainedthe conventional circuit getting 86% efficiency the proposed systemgetting 96% of efficiency as shown the efficiency table- 3. Conven-tional and proposed method verified. In future discussed differentkind of controller used to simulate the closed system

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implementation of zvs resonant converter with … · llc resonant converter with a center-tapped...

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