Reverse recovery characteristics, Electrical Engineering

Assignment Help:

Reverse Recovery Characteristics

At the end of forward  conduction in diode  reverse current  flows for  a short  time. The  device  doesn't  attain its full blocking  capability  until  the reverse current  cease. The  reverse current flows  in the interval called  reverse  recovery time. During  this time  charge  carriers stored in the diode at the end of forward  conduction are removed. Actually when a  power diode  has been conduction in the  forward direction sufficiently long to  establish  the steady state there  will be a charge  due to  minority  carriers  present. Before  the device  can  block in the reverse direction  this charge  must be extracted.

This  extraction takes  the from  of a transient reverse current and this  together  with the  reverse bias  voltage results in additional power  dissipation  which reduces the rectification efficiency.  Reverse recovery time is measured  instant the current recovers to 25% of its peak  reverse value. low  reverse state forward  current and low reverse bias  voltage increase recovery time. High  rate of all of anode  current reduces recovery time but  increase stored charge. High  junction temperature is  increase both   recovery time and  stored charge.

There  are two  parts of  reverse recovery  time. One  is the time  between  zero  crossing  of forward current  and peak reverse current. During  this time  period, charges stored  in  depletion  region  is removed.  The other part  of t measured form the instant of peak reverse current to the instant where  25% of peak reverse  current  is reached. During this time period charges from the two  semiconductor layer are removed.

The  shaded  area in figure  represents  the stored  charge  or reverse  recovery charge  which  must be  removed  during  the reverse recovery time. The  ration ½ is known  as softness factor. Voltages  transient occurs during  the time  diode  recovers is measured by the factor.

b.   forward  voltage  drop vf and forward  current  if gives  the power  loss  in a diode.  The total power  loss in  given by  average value of V f i f  during  time t2 major power  loss  occurs  in a diode. As shown in  figure peak reverse current  IFP is given by

 I =  RP = t1 di/ dt

Where Do/ dt  is the  rate of  rise of  reverse  current. If  the reverse  recovery  characteristics  is assumed as a triangle shape  then storage charge  Q can be written as .

Q =  ( ½) (IRP ) (t rr).


Related Discussions:- Reverse recovery characteristics

Diode model , Find I and V in the figure using ideal diode model

Find I and V in the figure using ideal diode model

Detrmine when the current flowing in the conductor, A conductor 300 mm long...

A conductor 300 mm long moves at a uniform speed of 4 m/s at right-angles to a uniform magnetic field of flux density 1.25 T. Verify the current flowing in the conductor when  (

Evaluate the transfer function of the nested-loop system, Q. Determine the ...

Q. Determine the transfer function C(s)/R(s) of the nested-loop feedback system shown in Figure.

Define the software defined radio, Software Defined Radio (SDR) is an advan...

Software Defined Radio (SDR) is an advanced radio technology in which flexibility is achieved in using radio functions such as modulation and demodulation of radio signals are carr

Calculate the induced armature voltage, Q. A 50-kW, 250-V, short-shunt comp...

Q. A 50-kW, 250-V, short-shunt compound generator has the following data: R a = 0.06 , R S = 0.04 , and R f = 125 . Calculate the induced armature voltage at rated load and t

What happen when negative bias applied to the gate of fet, Q. What happens ...

Q. What happens when a negative bias is applied to the gate of a FET? The result of applying a negative bias to the gate is to reach the saturation level at a lower level of V

Explain the procedure of binary to hex conversion, Q. Explain the procedure...

Q. Explain the procedure of Binary to Hex Conversion? It is simple to convert from an integer binary number to hex. This is completed by: Break the binary number int

How to get solution in taxation assignment help, i need help with taxation ...

i need help with taxation assignment help, how do i get solution for it?

SUPERPOSITION THEOREM, CONCLUSION IN BRIEF OF SUPERPOSITION IN ASSIGNMENT

CONCLUSION IN BRIEF OF SUPERPOSITION IN ASSIGNMENT

Blanking circuit, Blanking circuit: The saw tooth sweep voltage applied to...

Blanking circuit: The saw tooth sweep voltage applied to the X places moves beam across the CRT tube in a straight horizontal line from left to right during the sweep or trace tim

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd