control technique 2

8/18/2019 Control Technique 2

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STEADY STATE

CONVERTERANALYSIS

ANJANA SAP, EEE


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BOOST CONVERTEREXAMPLE• switched-mode convete th!t is c!"!#$e o%

"od&cin' ! dc o&t"&t vo$t!'e 'e!te inm!'nit&de th!n the dc in"&t vo$t!'e


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• A""$( sm!$$-i""$e !""o)im!tion !nd "inci"$eso% ind&cto vo$t-second #!$!nce !nd c!"!citoch!'e #!$!nce to *nd the ste!d(-st!te o&t"&t

vo$t!'e !nd ind&cto c&ent


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Sintev!$ +, switch in "osition +

Sintev!$ , switch in "osition


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• These e.&!tions c!n #e &sed to s/etch ind&ctovo$t!'e !nd c!"!cito c&ent w!ve%oms

• It c!n #e in%eed %om ind&cto vo$t!'ew!ve%oms th!t dc o&t"&t vo$t!'e V 0 V'1


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Ind&cto vo$t-second #!$!nce

The voltage conversion ratio M(D) is the ratio of theoutput to the input voltage of a dc-dc converter.


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Convesion !tio M(D) o% the #oost convete

• D 2 34 V 2 V'1

• V ince!ses !s D ince!ses

• Ide!$$( V → ∞ !s D → 1.

Practically there arelimits to output voltagethat can be produced bya practical boost

converter


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Detemin!tion o% ind&cto c&ent dc com"onent

• #( &se o% the "inci"$e o% c!"!cito ch!'e#!$!nce


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• Convete e$ements , ide!$

• Convete in"&t "owe 2 o&t"&t "owe

• Since convete o&t"&t vo$t!'e 0 in"&t vo$t!'e5

in"&t c&ent m&st #e 0 o&t"&t c&ent

• Ind&cto c&ent which coincides with the dc in"&tc&ent is 'e!te th!n the $o!d c&ent1

• ind&cto c&ent 6ows tho&'h semicond&cto

%ow!d vo$t!'e do"s5 the ind&cto windin'esist!nce5 !nd othe so&ces o% "owe $oss1

• As D → 1, ind&cto c&ent #ecomes ve( $!'e5$e!ds to $!'e "owe $osses1

•

i1e15 eciency of the boost converterdecreases rapidly at high duty cycle.


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Detemin!tion o% ind&cto c&ent i""$e


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Detemin!tion o% c!"!cito vo$t!'e i""$e


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B&c/-Boost Convetee)!m"$e

T( (o&se$%777


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C&/ convete e)!m"$e

• "e%oms ! dc convesion %&nction simi$! to the#&c/-#oost convete,

• it c!n eithe ince!se o dece!se the m!'nit&deo% the dc vo$t!'e5 !nd it invets the "o$!it(1


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• O"e!tes vi! c!"!citive ene'( t!ns%e


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8!ve%oms d&in' sintev!$ +, MOS9ETcond&ction intev!$


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8!ve%oms d&in' sintev!$ , Diode cond&ctionintev!$


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Ind&cto vo$t-second #!$!nce , !ve!'e v!$&e is :eo


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C!"!cito ch!'e #!$!nce , !ve!'e c!"!citoc&ent is :eo

NT!" During both subintervals# the capacitor currenti$% & i% - ' % . *hen ripple is neglected# i$% is constant

and e+ual to ,ero.


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C&/ convete convesion !tio M(D) 2 ' ;'g


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Ind&cto c&ent w!ve%oms


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C!"!cito $+ w!ve%om


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Ri""$e m!'nit&des

• D&in' the *st sintev!$5 the .&!ntities i+


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control technique 2

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