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1-Phase DiodeRectifiers

Diode Rectifier Block Diagram

Uncontrolled utility interface (ac to dc)

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S. Rajakaruna 2009 Power Electronics 3

A Simple Circuit

Resistive load

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A Simple Circuit ( R-L Load)

Current continues to flows for a while even after the inputvoltage has gone negative

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S. Rajakaruna 2009 Power Electronics 5

A Simple Circuit (Load has a dc 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-emf

S. Rajakaruna 2009 Power Electronics 6

Single-Phase Diode Rectifier Bridge

Large capacitor at the dc output for filtering and energystorage

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S. Rajakaruna 2009 Power Electronics 7

Diode-Rectifier Bridge Analysis

Two simple (idealized) cases to begin with

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Redrawing Diode-Rectifier Bridge

Two groups, each with two diodes

Only one diode from each group will conduct.

In the top group, the diode with its anode connected to the highestpositive potential will conduct.

In the bottom group, the diode with its cathode connected to thehighest negative potential will conduct.

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S. Rajakaruna 2009 Power Electronics 9

When V s>0, D 1 and D 2 conduct. When Vs