Engr. Affifa Adeeb

The Islamia University of BahawalpurUniversity College of Engineering &

Technology

EEN-324EEN-324Power ElectronicsPower Electronics

Three-Phase Uncontrolled Three-Phase Uncontrolled RectifiersRectifiersChp#7Chp#7

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ADVANTAGES OF THREE-PHASE RECTIFIERS OVER SINGLE-PHASE RECTIFIERS

1. Higher output voltage for given input voltage.

2. Lower amplitude ripples i.e., output voltage is smoother

3. Higher frequency ripples, simplifying filtering(lower size of filter circuit parameters because of higher ripple frequency)

1. Higher overall efficiency 2

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THREE-PHASE HALF-WAVE RECTIFIERS

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THREE-PULSE RECTIFIERS

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Circuit Diagram Load voltage waveforms

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Current Waveforms

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Period On diode

Offdiodes

VD1 VD2 VD3

030 ° D3 D1 & D2 VAC VBC 0

30 º150º D1 D2 & D3 0 VCA VCA

150º 270º D2 D3 & D1 VBC 0 VCB

270º390º D3 D1 & D2 VAC VBC 0

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Voltage across diodes

VD1

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VD2

9

VD3

1010

With Inductive Load

THREE-PHASE FULL-WAVEBRIDGE RECTIFIERS

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SIX-PULSE RECTIFIERS

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Equivalent circuits of six-pulse rectifier

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Diode and Line current waveforms

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With Inductive (RL) Load

TWELVE-PULSE RECTIFIERS

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Circuit Diagram

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