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full-wave bridge rectifier hard question

mujahed

May 1, 2020
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A full-wave bridge rectifier is used to supply an average voltage of 12V to 200-ohm load. The output voltage has 0.5% ripple. The rectifier is fed from a 310V(peak) at 50Hz by a transformer. Assume V(gamma) is 0.7V

Find:
a) The transformer turns ratio
b) the filter capacitor?
c) the present of time for which each diode conducts
d) the Peak Inverse Voltage of the diodes
 

Harald Kapp

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Nov 17, 2011
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Start by drawing the relevant circuit.
You'll have to assume an ideal transformer as no specific transformer parameters are given.
Calculate backwards:
  • Use the given average output voltage, load resistance and ripple to determine the required filter capacitor. You should have learned how to do that before. Or look up the required equations.
  • Having the value of the capacitor you should now be able to calculate the conduction time of the diodes (the diodes will conduct only as long as the sinusoidal output voltage of the transformer is higher than the voltage across the filter capacitor minus the voltage drop across the diodes (I assume that is V(gamma)?).
  • You now have the peak output voltage of the transformer. Peak input voltage is given. Calculate the turns ratio from these two.
  • You also have now all the data to calculate the peak reverse voltage of the diodes.

Come back and show us your calculations for verification.
 
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