power electronics engineering soumen Das .pdf

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About This Presentation

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TOPIC: UNCONTROLLED RECTIFIER
NAME – SOUMEN DAS
DEPARTMENT - ELECTRICAL ENGINEERING
ROLL NO – 35001622039
REG NO – 223500110137
SUBJECT – POWER ELECTRONICS
SUBJECT CODE – PC-EE504
SEMESTER – 5 th
YEAR – 3 rd
SESSION – 2022-2026
COLLEGE – RAMKRISHNA MAHATO GOVERNMENT ENGINEERING COLLEGE, PURULIA

TABLE OF CONTENTS:
1. SINGLE PHASE HALF WAVE RECTIFIER
2. SINGLE PHASE HALF WAVE RECTIFIER(R LOAD)
3. SINGLE PHASE HALF WAVE RECTIFIER (RL LOAD)
4. SINGLE PHASE FULL WAVE RECTIFIER (CENTER TAPPED)
5. SINGLE PHASE FULL WAVE BRIDGE RECTIFIER
6. THREE PHASE BRIDGE RECTIFIER

SINGLEPHASEHALFWAVERECTIFIER:
➢During each “positive” half cycle of the AC sine wave, the diode is forward biased as the anode is
positive with respect to the cathode resulting in current flowing through the diode.
➢ Since the DC load is resistive (resistor, R), the current flowing in the load resistor is therefore
proportional to the voltage (Ohm´s Law), and the voltage across the load resistor will therefore be the
same as the supply voltage, V s (minus V f), that is the “DC” voltage across the load is sinusoidal for the
first half cycle only so V out = V s.
➢ During each “negative” half cycle of the AC sinusoidal input waveform, the diode is reverse biased as
the anode is negative with respect to the cathode.

Therefore,NOcurrentflowsthroughthediodeorcircuit.Theninthenegativehalfcycle
ofthesupply,nocurrentflowsintheloadresistorasnovoltageappearsacrossitso
therefore,Vout=0

SINGLEPHASEHALFWAVERECTIFIER(RLOAD):
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SINGLEPHASEHALFWAVE
RECTIFIER(RLLOAD):
CurrentI0continuestoflowevenaftersourcevoltageVSisnegativebecauseofthe
presenceofinductanceLinload.
After+vehalfcycle,dioderemainsON,so–vehalfcycleappearsacrossloadcurrent
untilI0decaystozeroat ωt=β.
WhenI0= 0 atωt=β;VL=0,VR=0andVSappearsas reversebiasacrossdiodeD.
Atβ,diodevoltageVDjumpsfrom0 toVMsinβwhereβ>π.
Hereβ=γistheconductionangleofthediode.

SINGLEPHASEHALFWAVE
RECTIFIER(RLLOAD):
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SINGLE PHASE FULLWAVE
RECTIFIER–(CENTRETAPPED):
Alsocalled Mid –pointrectifier.
Theturnsrationfromeachsecondarytoprimaryis takenasunityforsimplicity.
When“A” is +vew.r.tmid–pointO, D1 conductsforπ radians.
When“B”is+vew.r.tmid–pointOinthenexthalfcycle,D2conductsfortheotherπ
radians.
PeakInverseVoltage(PIV)forbothD1andD2is2VSandhenceitiscalled1–φ2–
pulsedioderectifier.

SINGLE PHASE FULLWAVE
RECTIFIER–(CENTRETAPPED):
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=1

SINGLE PHASE FULLWAVEBRIDGERECTIFIER:
Onthepositivehalfcycleoftransformersecondarysupplyvoltage,diodesD1andD2
conduct,supplyingthisvoltagetotheload.
Onthenegativehalfcycleofsupplyvoltage,diodesD3andD4conductsupplyingthis
voltagetotheload.
ItcanbeseenfromthewaveformsthatthepeakinversevoltageofthediodesisonlyVm
Theaverageoutputvoltageisthesameasthatforthecentre-tappedtransformerfull-
waverectifier.
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SINGLE PHASE FULLWAVEBRIDGERECTIFIER:
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THREE PHASE BRIDGERECTIFIER:
Twoseriesdiodesarealwaysconductingwhilefourdiodesareblocking.
Oneoftheconductingdiodesisoddnumberedwhiletheotherisevennumbered.
Eachdiodeconductsfor120º.
Currentflowsoutfromthemost+vesourceterminalthroughanoddnumbereddiode
throughtheloadfollowedbytheevennumbereddiodeandthenbacktothemost–ve
sourceterminal.
Outputhaslessripplesandthediodesarenumberedinaccordancetotheirconductance.
Thebridgeusesboththe+veand–vehalvesofthei/pvoltage.
Ripplefrequencyis6*f.
Uppersetofdiodesconstitutesthe+vegroupwhilethelowersetconstitutesthe–ve.
TransformerPrimary–SecondaryisinDelta–Starconfiguration.

THREE PHASE BRIDGERECTIFIER:
Thediodewiththemost+vevoltagewillbeconducting.
Bischosenasreference.
During0º-30º,thevoltageatCishighest(arbitrarily).HenceD5isconductingasitis
themost+ve.
Between30ºand 150º,Abecomes themost+veand henceconducting.
During150º-270º,Bbeingmost+veconducts.
Thecyclerepeatsitself.
Eachdiodeconductsfor120º.
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THREE PHASE BRIDGERECTIFIER:

THREE PHASE BRIDGERECTIFIER:
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�0
=0.9558∗??????;??????
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3
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1
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=99.82%
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63
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6
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