LITERATURE REVIEW

JOURNAL 3

RECTIFIER

There are several ways of connecting diodes to make a rectifier to convert AC to DC. The bridge rectifier is the most important and it produces full-wave varying DC. A full-wave rectifier can also be made from just two diodes if a centre-tap transformer is used, but this method is rarely used now that diodes are cheaper. A single diode can be used as a rectifier but it only uses the positive (+) parts of the AC wave to produce half-wave varying DC.

Bridge rectifier

A bridge rectifier can be made using four individual diodes, but it is also available in packages containing the four diodes required. It is called a full-wave rectifier because it uses all the AC wave (both positive and negative sections). Alternate pairs of diodes conduct, this changes over the connections so the alternating directions of AC are converted to the one direction of DC.

Bridge rectifiers are rated by the maximum current they can pass and the maximum reverse voltage they can withstand. Their voltage rating must be at least threetimes the RMS voltage of the supply so the rectifier can withstand the peak voltages.

Single diode rectifier

A single diode can be used as a rectifier but this produces half-wave varying DC which has gaps when the AC is negative. It is hard to smooth this sufficiently well to supply electronic circuits unless they require a very small current so the smoothing capacitor does not significantly discharge during the gaps. 

Credit to : Prajapati Dipali, K., Raj Roshani, D., Patel Komal, C., & Hilali Marhaba, A. ( 2014). Automatic Gate Opening System For Vehicles With RFID or Password.