Full Wave Bridge Rectifier – Circuit, waveforms and working principle

Full wave bridge rectifier:

This post provides an information about full wave bridge rectifier. We will also see its working principle and advantages and disadvantages.

In full wave Bridge rectifier a transformer and four diodes are used. During the positive half cycle of secondary voltage, the diodes D2 and D4 are forward-biased, but diodes D1 and D3 do no conduct. The current is through D2, R, D4 and secondary winding.

During the negative half cycle, the diodes D1 and D3 are forward-biased, but diodes D2 and D4 do not conduct. The current is through D1, secondary winding, D3 and R.

The load current is in the same direction in both half-cycles. Therefore a unidirectional (d.c.) voltage is obtained across load resistor.

Average voltage = Vdc = 0.636 Vp = 2Vp/p

Where Vp = peak value of secondary voltage.

Since each diode conducts for only half cycle, the current rating (Io) of the diodes must be at least – half of the dc load current. i.e. 0.5 Idc.

Each diode must withstand a peak inverse voltage equal to the peak secondary voltage. PIV = Vp.

Therefore the PIV rating of the diodes must be greater than Vp. As the output is a full-wave signal, the output frequency is double the input frequency.

The maximum efficiency of bridge rectifier is 81.2%

Advantages of full wave bridge rectifier:

• Centre tap on the secondary of the transformer is not necessary.
• Small transformer can be used.
• For a bridge rectifier circuit PIV per diode is one-half of the value for each diode in a full-wave rectifier.

Disadvantages of bridge wave rectifier:

• In this type two extra diodes are used.
• The voltage regulation is poor.

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1. Stanley Marlow says: