switching characteristicsthe switching

Question

Switching Characteristics

The switching  characteristic  of an IGBT  during  turn on and turn off time all  shown  in the sum of delay time  and rise time gives  the total  turn on time  here delay time is the time during which collector to  emitter voltage falls 10% it means from V_CE to 90% of V_CE  where V_CE=  initial collector emitter voltage. The rise time  is the time during  which collector  current  from it initial leakage current  ( I_CE)  to 10%  of I_C where I_C =final  of collector current therefore,

 Ton = T _J  + t_r

The  on state  forward voltage drop across the  device is also  shown in figure  as V_CES.  The turn off  time of IGBT  can be  divide into there intervals delay time I_do initial  and final fall  time therefore  total turn  off times 

T_off = t _do + T _if + t_ff

The delay  time during  turn off defined as a time during  which  the gate voltage  falls  from V_GE to threshold voltage  V_GE. Due  to this collector current  falls from I_C  to 90% of I_C. At the  end of this  delay  time V_CE being  to rise.  During  initial  fall time  t_if collector current falls forms 90%  to 20%  of initial  value of I_C and V_CE rises  from on state  forward drop to 10%  of V_CE,. During  final fall  time t_rf  collector current falls from 20% to 10%  of initial  of I_C and V_CE rises from  1% of V_CE final  value of V_CE