Interleaved Buck Converter for Fast PWM Dimming of High –Brightness LEDs

A Project report on

Interleaved Buck Converter for Fast PWM Dimming of High –Brightness LEDs

In partial fulfillment of the requirements for the award of the degree of

BACHELOR OF TECHNOLOGY

 in 

Electrical and Electronics Engineering

Submitted by

S.Brunda Vihari Chowdary

Pushpak Agarwal

Under the esteemed guidance of

Dr.N.Vishwanathan

 Professor

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DEPARTMENT OF ELECTRICAL ENGINEERING

NATIONAL INSTITUTE OF TECHNOLOGY

WARANGAL -506004 (Telangana)

APRIL-2015

DEPARTMENT OF ELECTRICAL ENGINEERING

NATIONAL INSTITUTE OF TECHNOLOGY

WARANGAL -506004

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CERTIFICATE

This is to certify that this is the bonafide record of the project work on “Interleaved Buck Converter for Fast PWM Dimming of High-Brightness LEDs” carried out by S.Brunda Vihari Chowdary, Pushpak Agarwal of Final year B. Tech (Electrical and Electronics Engineering) during the academic year 2014-2015 in the partial fulfillment of the requirements for the award of the degree of the Bachelor of Technology.

Project Guide:

Dr.N.Vishwanathan                                                    Dr.N Vishwanathan

Professor                                                            Professor & Head

Dept. of Electrical Engineering                                Dept. of Electrical Engineering

National Institute of Technology                                National Institute of Technology

Warangal                                                        Warangal

APPROVAL SHEET

This Project Work entitled by Interleaved Buck Converter for Fast PWM Dimming of High-Brightness LEDs by S.Brunda Vihari Chowdary and Pushpak Agarwal is approved for the Degree of Bachelor of Technology, ELECTRICAL Engineering.

Examiners:

______________________

______________________

______________________

Advisor:

Prof. N.Vishwanathan

Chairman

Prof. N.Vishwanathan

(H.O.D)

Date: _________________

Place: _________________

DECLARATION

We declare that this written submission represents our ideas in our own words and where other ideas or words have been included; we have adequately cited and referenced the original sources. We also declare that we have adhered to all the principles of academic honesty and integrity and have not misinterpreted or fabricated of falsified any idea/data/fact/source in my submission. We understand that any violation of the above will be cause for disciplinary action of the institute of and can also evoke penal action from the sources which have thus not been properly cited or from whom proper permission has not been taken when needed.

S.Brunda Vihari Chowdary

UG112153

Pushpak Agarwal

UG112102

Date: ______________

AKNOWLEDGEMENT

We wholeheartedly thank our guide Dr.N.Vishwanathan, Professor, Department of Electrical Engineering, for being a source of motivation and guiding me with perfection in doing this work.

We are grateful to Dr. N Vishwanathan, Professor and Head of Electrical Engineering Department, for providing us with all the facilities to carry out this project work. We are immensely thankful to him for his moral support to carry out this Project.

We consider it as a great privilege to express our deep gratitude to many respected personalities who guided, inspired and helped us in the successful completion of the project.

We are also thankful to all our friends who have given valuable suggestions and help in all stages of the development of the project.

Finally, we would like to dedicate this work to our parents who have provided support and encouragement during every part of our life

S.Brunda Vihari Chowdary, UG1122

Pushpak Agarwal,UG1122

ABSTRACT

At present, some of the most important strategic efforts in research are the increasing efficiency of power systems and the enhanced control strategies that allow a more rational use of the energy, as well as an increase in power savings. In this scenery, major advances have been carried out recently in lighting systems, at the level of improved efficiency light sources as well as in power topologies and schemes or control strategies.

        In this project we evaluated the interleaved buck converter as a high-brightness (HB) LEDs electronic driver by comparing its performance with the standard buck converter. The main drawbacks of the standard converter come from the high inductor value necessary to guarantee low output current ripple, which result in high inductor losses and rough switching waveforms at the semiconductors. Additionally, when the application demands pulse width modulation (PWM) dimming, this high inductance value yields to a relatively low dimming frequency that can result in audible noise problems due to several phenomena as magnetostrictive effects at the inductors or piezoelectric effects at the capacitors.

        The proposed interleaved converter obtains low output current ripple with much smaller inductances, thus allowing PWM dimming at higher frequencies (20 kHz and beyond), avoiding audible noise. The interleaved buck converter also yields to higher efficiencies than in standard buck converter. Simulation results of both standard and interleaved converter are compared and discussed with adequate support of calculations.

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