Full Wave Rectification

A full-wave rectifier converts the whole of the input waveform to one of constant polarity (positive or negative) at its output. Full-wave rectification converts both polarities of the input waveform to DC (direct current), and is more efficient.

Full wave rectification:





The positive half cycle:

During the positive half cycle of the supply, diodes D1 and D2 conduct in series while diodes D3 and D4 are reverse biased and the current flows through the load as shown below








The negative half cycle:

During the negative half cycle of the supply, diodes D3 and D4 conduct in series, but diodes D1 and D2 switch of as they are now reverse biased. The current flowing through the load is the same direction as before.



Full wave rectification for smoothing DC:

With the full wave rectification we get the pulsating DC with the ripples.For smooth DC we use capacitors to remove ripples.





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Half Wave Rectification

In half wave rectification, either the positive or negative half of the AC wave is passed, while the other half is blocked. Because only one half of the input waveform reaches the output.Half wave rectification can be achieved with a single diode in a one phase supply, or with three diodes in a three-phase supply.

During the first half cycle of the waveform the diode is forward biased and current flows around the circuit formed by the diode, the transformer winding and the load.
During the second half cyclethe diode is reverse biased and no current flows.
The diode only conducts on every other half cycle. Hence, HALF-WAVE RECTIFICATION.
The rectified voltage is DC (it is always positive in value). However, it is not a steady DC but PULSATING DC. It needs to be smoothed before it becomes useful.

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