What Is a Rectifier? What Are its Various Types?
A rectifier is an electronic device that changes alternating current into direct current. This process is called rectification.
The three main types of rectifier are as follows:
Half-wave rectifier: It is the simplest type of rectifier, which is made with just one diode.
i. When the voltage of the alternating current is positive, the diode becomes forward-biased and current flows through it.
ii. When the voltage is negative, the diode is reverse-biased and the current stops.
iii. The result is a cropped copy of the alternating current waveform with only positive voltage. This pulsating direct current is adequate for some components, but others require a more steady current.
Full-wave rectifier: This rectifier is essentially made of two half-wave rectifiers, and can be made with two diodes and an earthed centre tap on the transformer. The centre tap allows the circuit to be completed because current cannot flow through the other diode.
i. When the voltage of the alternating current is positive, one of the diodes become forward biased whereas the other gets reverse biased. Hence, current flows through the forward biased diode.
ii. When the voltage of the alternating current is negative, the previous reverse biased diode becomes forward biased whereas the other gets reverse biased. Hence, current flows through the forward biased diode.
iii. Thus, current flows at least through one of the diodes at a time. Therefore, the result is still a pulsating direct current but with double the frequency.
Bridge rectifier: A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification.
i. The main advantage of this bridge circuit is that it does not require a special centre tapped transformer, thereby reducing its size and cost.
ii. The single secondary winding is connected to one side of the diode bridge network and the load to the other side as shown below.
iii. The result is still a pulsating direct current but with double the frequency.