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

Explain idiv instructions in 8086 family, Explain IDIV instructions in 80...

Explain IDIV instructions in 8086 family with example and their effect on flag. IDIV: It used to divide a 16-bit signed number with an 8-bit signed no. or 32 bit signed numb

Determine the input resistance between terminals of circuit, Q. Consider Fi...

Q. Consider Figure of the weighted differencing amplifier. Let R 3 = R 1 and R 4 = R 2 . Determine the input resistance between terminals a and b of the circuit.

Determine the total active power, Determine the total active power: Ci...

Determine the total active power: Circuit is introduced in the Face 1. It is about a single-wires face for a three-phase system. The voltage of the AC source is of 69kV. The s

Explain the application of clippers, Q. Explain the application of clippers...

Q. Explain the application of clippers. There are numerous clipper applications. In general clippers are used to perform one of the following two functions: · Changing the s

Calculate the diameter of copper wire, Calculate the diameter of copper wir...

Calculate the diameter of copper wire of length 100 metres used as winding material in a transformer such that the resistance of the whole winding is 2 ohms. Calculate the diameter

Differentiate between n and p type semiconductors, Differentiate between n ...

Differentiate between n and p type semiconductors. n - Type semiconductor:- (i) If small amount of pentavalent impurity is added with, to a pure semiconductor giving a la

Explain the synchronous machines, Explain the Synchronous Machines? A s...

Explain the Synchronous Machines? A synchronous machine, unlike an induction (or asynchronous) machine, only develops torque at a fixed, so called, synchronous speed - n s whi

Working of harmonic distortion analyzer, Q. Explain with the help of a bloc...

Q. Explain with the help of a block diagram the working of harmonic distortion analyzer. OR Write short note on Harmonic distortion analyzer. Sol. Several methods h

Energy, Explain different stage in energy audit?

Explain different stage in energy audit?

Change of phase, Write an m-file "myfourier.m" which takes two images, comp...

Write an m-file "myfourier.m" which takes two images, computes FFT, phase and amplitude and swaps the amplitudes between two images. function myfourier im1=imread('cameraman.pn

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