Full wave bridge rectifier


In the bridge circuit four diodes are connected in the form of a Wheatstone bridge, two diametrically opposite junctions of the bridge are connected to the  secondary of a transformer and the other two are connected to the load.

Full wave bridge rectifier

Full-wave-bridge-rectifier

Peak Inverse Voltage of a Full wave bridge rectifier:

Merits and Demerits of Full-wave Rectifiers Over Half-Wave Rectifiers.

Merits.

l.The rectification efficiency of full-wave rectifier is double of that of a half-wave rectifier

2.The ripple voltage is low and of higher frequency in case of a full-wave rectifier so simple filtering circuit is required.

3.Higher output voltage higher output power and higher TUF in case of a full-wave rectifier.

4.In a full-wave rectifier, there is no problem due to dc saturation of the core because the dc currents in the two halves of the transformer secondary flow in opposite directions.

Demerits. Full-wave rectifier needs more circuit elements and is costlier.

Merits and Demerits of Bridge Rectifiers Over Centre-Tap Rectifiers.

With the availability of low-cost, highly reliable and small-sized silicon diodes bridge rectifier is becoming more and more popular in comparison to centre-tap rectifier. It has many advantages over a centre-tap rectifier, as given below.

1.No centre tap is required in the transformer secondary so in case of a bridge rectifier the transformer required is simpler. If stepping up or stepping down of voltage is not required, transformer can be eliminated even.

2.The PIV is one half that of centre-tap rectifier. Hence bridge rectifier is highly suited for high voltage applications.

3.Transformer utilisation factor, in case of a bridge rectifier, is higher than that of a centre-tap rectifier.

4.For a given power output, power transformer of smaller size can be used in case of the bridge rectifier because current in both (primary and secondary) windings of the supply transformer flow for the entire ac cycle.

The main drawback of a bridge rectifier is that it needs four diodes, two of which conduct in alternate Half-cycles. Because of this the total voltage drop in diodes becomes double of that in case of a centre-tap rectifier. An­other drawback of bridge rectifier is that the load resistor RL and the supply source have no common point which may be earthed.

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