Tuesday, 11 December 2012

Rectifier Circuit, Rectifier Theory, Half Wave Rectifier, Full Wave Rectifier, Rectifier Diode



Rectifier Circuit, Rectifier Theory, Half Wave Rectifier, Full Wave Rectifier, Rectifier Diode


RECTIFIER: The circuit which converts AC into DC is called Rectifier Circuit.





There are basically two types of Rectifier Circuit:
1)      Half wave Rectifier
2)      Full wave Rectifier
(a)    Centre Tap Full Wave Rectifier
(b)   Bridge Full Wave Rectifier


1). HALF WAVE RECTIFIER

This is the simplest Rectifier Circuit. The circuit has only one diode.



IN POSITIVE CYCLE OF THE INPUT AC VOLTAGE:

When the input voltage is positive the anode of diode is +ve and the cathode of diode is –ve. This results in forward biasing of the diode. When the diode is forward bias it behaves as a short circuit. As a result we get the input voltage at the output of the circuit. As a result we get the input voltage at the output of the circuit.

IN NEGATIVE CYCLE OF THE INPUT VOLTAGE



When the inputs reverse its cycle the anode of the diode become –ve. This reverse biases the diode. As a result the diode behaves as open circuit. No current can flow in the circuit and the output voltage we get is zero.

PERFORMANCE OF HALF WAVE RECTIFIER


The current wave of half wave rectifier




THE TOTAL RMS VALUE:


RIPPLE FACTOR (r):


RECTIFICATION EFFICIENCY (ŋ):



FULL WAVE RECTIFIER

There are two types of Full wave rectifier:

(a)  CENTRE TAP RECTIFIER
(b)  BRIDGE RECTIFIER


(a) CENTRE TAP RECTIFIER

Centre tap rectifier uses a centre tap transformer, two diodes D1 and D2.


DURING +VE HAALF CYCLE:

At this time the polarity of the two voltages Vs will be shown in figure below:


With this polarity D1 will be forwarded biased and D2 will be reverse biased. D1 will behave as short circuit and D2 will be open circuit.



The current will flow in the upper part of the circuit and no current will flow in the lower part. The current will flow through the load in the shown direction and the polarity of the voltage drop in the load will be as shown in the figure above.




DURING –VE HALF CYCLE:

During –ve half cycle the D1 will be open circuit and D2 will be short circuit. The current in the circuit is as shown in the fig. Note the direction of current is same through the load resistance as the current is +ve half cycle. As the current is unidirectional in the complete cycle we can say we have got a DC


PEAK INVERSE VOLTAGE (PIV)

It is the largest reverse voltage that is expected to appear across the diode. In centre tap rectifier the PIV of each diode should be 2 Vm where Vm is the peak input voltage at the secondary of transformer.



(b) BRIDGE RECTIFIER



DURING +VE CYCLE
            In this input diodes D1 and D3 are forward bias. The flow of current will be as shown in figure below:



DURING –VE CYCLE
            At this moment diodes D2 and D4 are forward bias and D1 and D3 are reverse bias. The flow of current will be as shown in figure below.


The flow of current is unidirectional therefore the voltage developed across the load is DC.


PEAK INVERSE VOLTAGE (PIV)

PIV of the diodes used in the circuit is Vm.

Performance of Full-wave Rectifier






            The DC Value:

The Total RMS Value: 


              Ripple Factor: 


              Rectification Efficiency:













4 comments:

  1. its informative and simple, very easy to understand thanx a lot.

    ReplyDelete
  2. Excellent explanation. Since exact calculation of current peak or true RMS of diode bridge is very hard due to high nonlinearity, some numerical simulation can be helpful.

    http://www.cirvirlab.com/simulation/diode_bridge_online.php

    ReplyDelete
  3. I can learn from this very easily.

    ReplyDelete