Monday, 17 September 2012

Bridge Rectifier

A Bridge Rectifier ( Full wave Rectifier )

The circuit in figure 3 addresses the second of these problems since at no time is the output voltage 0V.  This time four diodes are arranged so that both the positive and negative parts of the AC waveform are converted to DC.  The resulting waveform is shown in figure 4.





When the AC input is positive, diodes A and B are forward-biased, while diodes C and D are reverse-biased.  When the AC input is negative, the opposite is true - diodes C and D are forward-biased, while diodes A and B are reverse-biased.

One disadvantage of the full-wave rectifier is that there is a voltage loss of 1.4V across the diodes.  Why not 2.8V as there are four diodes, that is because there is only two of the diodes are passing current at any one time.

While the full-wave rectifier is an improvement on the half-wave rectifier, its output still is not suitable as a power supply for most circuits since the output voltage still varies between 0V and Vs-1.4V.  So, if you put 12V AC in, you will 10.6V DC out.


The formula Bridge full wave Rectifier is,


 Full wave   Bridge
Number of   diodes


4

PIV of diodes


Vm


D.C output voltage

2Vm/phi


Vdc,at
no-load                 

0.636Vm


Ripple factor

0.482

    Ripple     
   frequency

2f

  Rectification
   efficiency

0.812

  Transformer
   Utilization
   Factor(TUF)  

0.812

RMS voltage Vrms
Vm/√2



 
A bridge rectifier makes use of four diodes in a bridge arrangement to achieve full-wave rectification. This is a widely used configuration, both with individual diodes wired as shown and with single component bridges where the diode bridge is wired internally. So, in this project it will use 4 x 1N4001 diode (as picture below).



Diode type 1N4001


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