Bridge and center-trapped full wave rectifiers

[M11]

Homework Statement

Why the output DC voltage of the center trapped rectifier is half that of a bridge rectifier??

 

[overt26]

If you mean for the same transformer primary-to-secondary ratio but with the center tap used in one case (with 2 diodes) and with the the total winding used in the other (with 4 diodes in a bridge configuration) - then yes that's true. In the first case only half the total secondary voltage is rectified on each half cycle whereas in the latter case the full secondary voltage is rectified on each half cycle of the mains waveform. If the CT case had a different transformer with a total secondary voltage twice that of the other, then the result would be the same - ignoring the diode voltage drops.

 

[Mene]

There are a few factors that contribute to the difference in output DC voltage between a center-trapped full wave rectifier and a bridge rectifier. Firstly, the center-trapped rectifier uses only two diodes, while the bridge rectifier uses four. This means that the center-trapped rectifier has a higher internal resistance, resulting in a lower output voltage.

Additionally, the center-trapped rectifier utilizes a transformer with a center-tapped secondary winding, which divides the input voltage in half. This means that the maximum voltage across the diodes is also halved, resulting in a lower output voltage.

On the other hand, the bridge rectifier uses four diodes in a full wave configuration, allowing for a more efficient conversion of AC to DC. The diodes are arranged in a way that allows for the full input voltage to be utilized, resulting in a higher output voltage.

Furthermore, the center-tapped rectifier has a larger ripple voltage, due to the fact that it only conducts during half of the input cycle. This results in a lower average output voltage compared to the bridge rectifier, which conducts during the entire input cycle.

In summary, the difference in output DC voltage between the center-trapped rectifier and the bridge rectifier is due to the number of diodes used, the transformer configuration, and the ripple voltage. Each design has its own advantages and disadvantages, and the choice between the two would depend on the specific application and requirements.