what is the difference in wave form of Vds if D2 is zero reverse recovery and if has reverse recovery time.can some one please draw the wave form , and this effect on the ringing of the MOSFET ?.

 

View attachment 93427 what is the difference in wave form of Vds if D2 is zero reverse recovery and if has reverse recovery time.can some one please draw the wave form , and this effect on the ringing of the MOSFET ?.

Sounds like homework.

 

Sounds like homework.

this is not a homework , this something I need to understand it, so can you please show what is the different in current and voltage of vds in both cases

 

This appnote has a pretty good explanation. A zero reverse recovery time is a physical impossibility, and although it can be made very short it just cannot be zero.

http://www.vishay.com/docs/84064/anphyexp.pdf

The effect of the non-zero reverse recovery time is that the diode will conduct in the reverse direction for some period of time. The characteristic is non-linear so the result will be distorted.

 

Hi,

The capacitance causes some ringing so you'll see ringing even with a small capacitance.
The recovery mechanism is considered to be a different phenomenon. The shorter the recovery time the shorter the reverse current pulse will be through the diode.