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AC-DC CONVERTER

Dr P.R.Thakura

ReaderDept of EEE

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Semi-controlled device Latches ON by a gate-current pulse if forward biased Turns-off if current tries to reverse

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Idealized switch symbol When on, current can flow only in the direction of the

arrow Instantaneous switching from one state to the other Zero voltage drop in on-state Infinite voltage and current handling capabilities

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UNCONTROLLED RECTIFIER(AC/DC)

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Resistive Load

Voltage & Current waveforms are in phase

Half-wave Rectifierwith Resistive Load.

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Voltageandcurrent waveforms ofthehalf-

wave Rectifierwith Resistiveload.

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Current continues to flows for a while even after the input

voltage has gone negative

A Simple Circuit (R-L Load)

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A Simple Circuit (Loadhasadc back-emf)

Current begins to flow when the input voltage exceeds the dc back-emf

Current continues to flows for a while even after the input voltage hasgone below the dc back-emf9BIT Mesra

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Full-waverectifierwithcenter-tapped

transformer.

There are two types of single-phase full-wave rectifier, namely,full-wave rectifiers with center-tapped transformer and bridge rectifiers.

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Voltageandcurrent waveforms ofthefull-wave

rectifierwithcenter-tapped Transformer.

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Bridge Rectifier

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Voltageand Current Waveforms ofthe

Bridge Rectifier

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Single-Phase Diode RectifierBridge

Large capacitor at the dc output for filtering and energystorage

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Three-Phase, Full-Bridge Rectifier

Waveforms

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CONTROLLEDRECTIFIER(AC/DC)

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Single Phasehalfcontrolled Converterwith

resistiveload.

Circuit Diagram Voltage & Current Waveforms

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Single thyristor rectifier (a)

(b) Motor load.

Resistive-Inductive Load

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BiphaseHalf-Wave Rectifier.

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Single-phase bridgerectifier:

Fully Controlled Rectifier

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Waveforms of a fully controlled bridge rectifier

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Waveforms of a fully controlled bridge rectifier with resistive-

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Single-phase bridgerectifier:

Semi controlled.

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Controlled conversion of ac into dc

Two-quadrant conversion

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3-Phase ThyristorConverters

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3-Phase ThyristorConverterWaveforms

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Output Waveform: (for Inductive load)

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Output Waveform:

DCvoltage when the delay angle > 90 , VD= - Ve

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Converter Behavior at various delay angle:

out put voltage,

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