POWER SEMICONDUCTOR DEVICES

Power electronics is a combination of two  engineering fields power  engineering  and electronics  engineering. In  power  engineering  the equipments  and apparatus  are rated at high  level and high  efficiency.  In electronics engineering, all  the apparatus are rated at signal  level without  much  consideration of efficiency.  Power engineering covers the transmission generation distribution  and utilization of electrical energy.  Transmission and  reception of data distortionless  production signals of very  low  power  level comes in electronics  engineering. Hence the apparatus of power  electronics  are rated at power  level but works  on the principle  of electronics.

The  electronics  power conversion circuit  use power  semiconductor  devices  and these  circuits convert  and control  electronics  power.  These  devices operate in the switching mode. Which  causes the losses to be  reduced and therefore  the conversion  efficiency its to be improved. The  disadvantages of switching  mode operation  are the generation of harmonics. Now  a days the technology  is advancing and apparatus  cost is decreasing along  with the improvement of reliability. Therefore  the applicant of power electronics  devices are expanding in industrial commercial residential military aerospace  and utility environments. The progress in power  electronics  is due  to advance in power  semiconductor devices.

In 1957  bell laboratories  were the  first to fabricate  a silicon based  semiconductor  device called  thyristor and it  was introduced by GEC. This  company  did a great  deal of  pioneering work  about the utility  of thyristors  in industrial application. Later  on many other semiconductor devices having characteristics identical to that of a thyristor ere developed and  these are traic. Dirac power  diode power BJT, power  MOSEFT SILICON CONTROLED  switch  programmable injunction transistor ( PUT) IGBT, S?IT ,SITH, GTO, MTC, RCT,  etc. This whole  family  of semiconductor devices  used for  power  control  in de and ac systems. Silition  controlled rectifier is one oldest member of this thyristor family and is  the most widely used device. At  present the use of SCR  is so vast  that over the years the world  thyristor has become synonymous with SCR. It appears that the term thyristor is now  becoming  more common  than the  actual  term SE
CR, in  this book  the term  SCR  and thyristor  will be  used at  random  for the  same  device SCR.

This  chapter  deals  the terminal V-1  characteristics and switching  characteristics  of power  diode power  transistor thyristor diac traic GTO  Power  MOSEFT. In the last  of this  chapter  two transistor  model of thyristor  has been  discussed.