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DC – DC Converter

Choppers

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AC Power Vs. DC Power

1. Power factor in AC Power.2. More Transmission drop in AC Power.3. Renewable ener! so"rces are mostl! DC

so"rce. #eeds to convert to AC for AC powerapplication.

$. Micro%rid applications.

&. 'se of electronic e("ipment. DC can be dire"sed w)ere as AC needs to be converted froAC to DC.

*. Direct solar panel DC o"tp"t can be "sed tooperate t)e )o"se)old appliances.

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Applications (DC House)

Unity power factor application

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Micro%rid Applications

LocalLoad

LocalGenerator

(Renewableenergysource)

DC - AC

Conertr

AC !ationalGrid

DC Grid

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DC Power +o"rces

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"ub#arine power syste#s$ "pacecrapower syste#s$Auto#obile applications$ DC #otor driAll electronic e%uip#ent li&e'

ersonal co#puters$ *ce e%uip#entLaptop co#puters$ +eleco# e%uip#enAudio-,isual syste#s$ Do#estic appliaRailway signaling

DC –DC power s"ppl!Applications

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T)e converterprod"ces a re"lo"tp"t voltae, )a manit"de -an

possibl! polarit!di/ers from t)e Voltae.

DC . DC Conerter (De/nition)

+tep%down -"c DC%DC Converter

"c % oost DC%DC Converter

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DC – DC Converter re("irem

1. "tp"t voltae ad4"stabilit!.2. ver c"rrent protection.3. +)ort circ"it protection.$. "tp"t side over voltae

protection.&. 0np"t side over voltaeprotection.

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asic DC – DC C)opper

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T+1 5 T# 6 T+2 5 T7

8 T77 

+witc)in 7re(D"t! c!cle D is de9

is e("al to -D 5 and -1%D

DC – DC Converter

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Aerage DC output oltage across the load ,

gien by'

V'T is alwa!s less t)an V0# 

"c C)opper

DC – DC Converter -"cC)opper

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R1" Co#ponent of output oltage across th

load ,U+(R1") is gien by'

:nowin VDC-Ave and VRM+ , 77 and R7 ca

be calc"lated

 

"c C)opper

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A meas"re for o"tp"t wave s)apedeviation, to re("ired o"tp"t wavs)ape -Constant DC val"e;

 

7orm 7actor < Ripple 7actor

2324345 U1 Rao

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 6

At an! D val"e, t)at is at an! V'T, =>cienc

=("ivalent Resistance of "c C)opper ts"ppl! is a

variable resistance 5 R0# 5

"c C)opper -Resistive oa

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Power 0np"t P0# 

5

"c C)opper % =>cienc!

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Actual loss factors in the circuit are'4 7orward ,oltage drop of 8n9 switch "4 (

cienc!

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"c C)opper – BP Anal!sis

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"c C)opper – Compon

7unda#ental fre%uency 6 f 6 "wifre%uency

 

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f + is switc)in fre("enc! and can be

)i), so can be 9ltered b! "sin a owPass 7ilter.

#ote; 5 2Ef and f is switc)infre("enc!, t)"s 9rst lowest )armonic is

e("al to switc)in fre("enc!.

Har#onic "pectru# - LH