MOSFET AND IGBT fail in pwm speed control for 260VDC 2200W universal motor

hi all i am new here , i was working the past 2 weeks to make PWM for an existing 240VAC 2200W but i will run it on DC 260V instead from 20 12V batteries for and electric car project i am working on i did try this circuit
**broken link removed**
with 555 timer but i changed the MOSFET to W26NM60N 26 amps 600V and IRFP460 20 amps 500V both run a small 12v 1A motor good but when trying the 2200w it fail after about 5 s when i try to increase the speed D and S go short circuit and sometimes g and d and s,
the next step i did is searching for MOSFET driver i did find several and try this one
http://www.sampson-jeff.com/tcrobowar/motor1/ver1.htm
(last circuit in the page)
and i connect a p mosfet to drive and IGBT GT80J101 80A 1kV which btw cost much
i did run the small motor but fail at the same way with the other
failed component didn't even get warm before failing
only once i try connecting 3 parallel IRFP460 and using first circuit it did run for a while all 3 were hot and in the second try only one get warm and fail
i did find this article very useful but it didnt solve my problem and i did connect fast diodes throw the motor terminals and throw D and S for safety reasons
all my trials has been stopped now i didn't know what to do and i have a deadline to finish the project before the end of this month
so help will be appreciated
thanks

First of all you have to ensure the right biasing of mosfet it should be near to peak value of the mosfet ie.12v to 20 v according to its datasheet.secondly add snubber across mosfet to protect it against back EMF. I hope it will solve your problem

skylarks said:

First of all you have to ensure the right biasing of mosfet it should be near to peak value of the mosfet ie.12v to 20 v according to its datasheet.secondly add snubber across mosfet to protect it against back EMF. I hope it will solve your problem

Click to expand...

thanks for your reply but how to select the appropriate snubber ?!