Full-Wave Bridge Rectifier

This rectifier circuit uses four diodes. Its simplified behaviour is shown in the animation and explained as follows:

During the positive half-cycle: Diodes D2 and D5 are forward-biased and conduct current which flows first out of the transformer into the D2's anode, then through RL, afterwards through the anode of D5 and then into the negative terminal of the secondary's winding. During this time, diodes D4 and D3 are reverse-biased.

During the negative half-cycle: Diodes D4 and D3 are forward-biased and conduct current which comes out of the terminal of the secondary windings (which in the previous half-cycle was "seen" by these diodes as negative and now as positive). Current enters first through the anode of D3, then proceeds through RL and ground into the anode of D4.


It is important to mention that the rectifier bridge is identified in diagrams with the symbol shown below, which is identical to the one in the animation, but with the diodes rotated. Some packages such as KBP201G shown below contain the whole rectifier bridge.


Bridge Rectifier Output Voltage:

For obvious reasons, a bridge rectifier's output average voltage is the same as that of the center-tapped full-wave rectifier: 


In order to calculate the bridge's peak output voltage, we take into consideration the fact that two diodes are simultaneously forward-biased during one half-cycle of the total secondary voltage.  


Peak Inverse Voltage:

The two reverse-diodes have a peak inverse voltage equal to the peak secondary voltage. The PIV across each reverse-diode considering the voltage drop at the diodes is shown in the following formula. The PIV rating of the bridge diodes is less than that required for the center-tapped configuration, unless use is made of diodes with half the PIV rating of those in a center-tapped rectifier for the same output voltage.


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