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DESIGN OF A FLYBACK CONVERTER FORIMPROVED CONVERSION EFFICIENCY AND

REDUCED NO-LOAD POWER LOSS.

Sachin George Thomas

Applied Electronics and Instrumentation

College of Engineering Trivandrum

Guided By :   Ms. Chandini G.S.

October 30, 2015

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Overview

Introduction

Motivation

Problem Definition

Methodology

References

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Introduction

 Most of the portable products in our lives are powered by d.cvoltage and ac-dc adapters are used for conversion from theac voltage to the required dc voltage.

 The ac-dc adapter is composed of a rectifier, a dc buscapacitor and a dc-dc converter.

 The dc-dc converter can be of the isolated type whichincludes flyback converters and forward converters or thenon-isolated type .

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Introduction

 The flyback convertor which comes under the category of isolated converter is of particular interest in this work.

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Motivation

 Compared to the flyback converters , the forward convertersrequires a reset winding , an output inductor and a free

wheeling diode which causes larger volume and more cost.

 Even the conventional flyback converters suffers from lowconversion efficiency and high no-load power loss.

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MOTIVATION

 Furthermore , the parasitic capacitance of the transformerbetween the primary and secondary windings needs to bereduced inorder to keep the common voltage under control.

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Problem Definition

Requirement for a flyback converter with improved conversionefficiency, reduced no-load power loss , and a power factorcorrection circuitry.

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Methodology

 Design of the lossless snubber circuit for suppressing thevoltage spikes

fig : Flyback convertor with RCD snubber

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Methodology

 Design of the energy recovery winding to recycle the energy

discharged from the gate -source capacitor of the main switch.

 Check for the feasibility of a Power Factor Correction (PFC)circuitry and if possible integrating the same.

 Integration of all the circuits .The simulation can be carriedout in SIMULINK/SIMPLIS.

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WORK PLAN

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References

 Ray-Lee Lin and Shih-Ho Hsu ,  ”Design andImplementation of Self-Oscillating Flyback Converter

With Efficiency Enhancement Mechanisms”  IEEETransactons on Industrial Electronics,Volume 62,Issue11,pages 6964-6955,November 2015

  J.Y.Guo,  ”Design and implementation of forward-flyback

converter with feed forward mechanism for mobile

phone”M.S thesis,National Cheng Kung University,May 2013

 Hao Ma , Yue Ji and Ye Xu,  ”Design and Analysis of 

Single-Stage Power Factor Correction Converter With a

Feedback Winding”  IEEE Transactons on PowerElectronics,Volume 25,Issue 6,pages 1460-1471,June 2010

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The End