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r a ns u eTechnology

Efciency Improvement Using LLCResonant Converter

Submitted by-

Diwakar Singh

kash Shrivastava

Utkarsh

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Objective

 !o Improve !he Efciency

Devices by ReducingSwitching Loss

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The Problem• !he switching Devices are turnon and o$ at the %oad current wa high di&dt va%ue'

•

 !his high vo%tage stress %eads tswitching power %oss which is ama(or contributor to the system%oss'

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Why Resonant Conver

• !he switching %osses can beremoved or minimi)ed i# theswitching devices are turned o

and o$ when the vo%tage or cuacross a device becomes )ero'

• !he vo%tage * current are #orcepass through )ero crossing by

creatin an LC resonant circuit

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 ResonantConverter?• +rob%em ,ith Series Resonant

Converter-

or the ma.imum efciency/ thecircuit needs to operate with itsswitching #re0uency at theresonant #re0uency'

1ut/ #or a continuous output

vo%tage/ the switching #or a seriesresonant converter needs to beabove the resonant #re0uency'

Due to this/ it has a %imit on how#ar the operating #re0uency can

be varied'

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• +rob%em ,ith +ara%%e% ResonantConverter-

Since the %oad is in para%%e% withthe resonant capacitor/ even atno %oad condition/ the input wi%%sti%% see a pretty sma%% impedanceo# the series resonant tank' !hiswi%% induce pretty high circu%atingenergy even when the %oad is)ero'

 !his %eads to it having a very high

turn o$ current at high inputvo%tage condition'

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• +rob%em ,ith Series-+ara%%e%Resonant Converter-

 !he conduction %oss and switching%oss wi%% increase at high input

vo%tage'

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LLC ResonantConverter

•  !his type o# circuit has tworesonant #re0uencies' "ne is

determined by the resonantcomponents Lr and Cr' !heother one is determined by Lm/Cr and %oad condition'

•  !his circuit makes sure that theswitching occurs within 23Sregion' !his is because/ in thecase o# 2CS/ the capacitiveturn-on %oss increases with theswitching #re0uency/ resu%tingin high current stress %eading toconduction %oss'

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•  !he designed operating regionsare region 4 and region 5'

• Region 6 is 2CS region' !heconverter shou%d be prevented

#rom entering region 6'

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Design Of Circuit

 !he parameters needed to be designed are7• !rans#ormer turns ratio7 n

•  Series resonant inductor7 Lr

•  Resonant capacitor7 Cr

•  Resonant inductor ratio7 Lm&Lr

 !he Specu%ated speci8cations #or the design are-

• Input vo%tage range7 699 3 to :99 3/ norma% operating region ;

• "utput vo%tage7 >9 3

• ?a.imum %oad7 5'> "hm

• ?a.imum switching #re0uency7 599 k@)

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Loss Comarison

• Use o# the Resonant Converter shou%d be ab%e toincrease the efciency by at %east 6A'

• or this part/ the %oss o# LLC resonant converter compared with symmetrica% @a%# 1ridge +,?Converter'

• Comparison wi%% be based on simu%ations andca%cu%ations' %% converters are designed with saSpeci8cations'

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Reference Research Pa

•

Efciency Improvement in d(ustab%e Deado# LLC resonant Converters/ +ub%ished inInte%%igent Breen 1ui%ding and Smart Brid;IB1SB=/ 594: Internationa% Con#erence onpri% 594:'

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 !hank ou