I meant to point out in one of my previous posts that there are high-voltage MOSFETs available with MUCH lower on resistance. This is just an example of what IR has. Other manufacturers will probably have similar offerings.
I also meant to mention that a beefy diode needs to be connected across the motor, anode to the drain of the MOSFET.

 

I meant to point out in one of my previous posts that there are high-voltage MOSFETs available with MUCH lower on resistance. This is just an example of what IR has. Other manufacturers will probably have similar offerings.
I also meant to mention that a beefy diode needs to be connected across the motor, anode to the drain of the MOSFET.

I too would countenance the use of a robust diode across the motor to protect the driver.

hgmjr

 

I ran some sims on an irfp450 driving a 10 Henry inductor in series with 30 ohms, and a 180V supply. What I found was that during the off transition, the power spikes to about one kilowatt for a very short period of time. I have no idea how long that spike can be before it becomes destructive, but the duration of it was directly proportional to how long it took for the gate capacitance to discharge, which is, of course, a function of how hard you drive the gate. If the OP can handle the inversion that comes with a common emitter driver, it will improve the turn off time by at least an order of magnitude.
Turn on time didn't seem to be a problem, even though it is slower, because the inductance of the load reduces the drain current slew rate so low that there is basically no power spike.
Obviously, this is just a simulation, so the results could be wrong. In addition, if you use a MOSFET with lower Rds(on), the gate capacitance will be higher, which will exacerbate the turn-off time problem (if it is a problem), necessitating a higher current driver.
I should add that any engineer with high-power MOSFET experience already knows all this. If any of it is incorrect, please straighten me out.

am dont have the experience in high-power MOSFET's thats my first project in it,
you mean that i should choice other mosfet which can handle more high current?
about the swiching speed i think that the mosfet is the highest speed of switching in the power elements,isnt it?

 

I meant to point out in one of my previous posts that there are high-voltage MOSFETs available with MUCH lower on resistance. This is just an example of what IR has. Other manufacturers will probably have similar offerings.
I also meant to mention that a beefy diode needs to be connected across the motor, anode to the drain of the MOSFET.

i think the power diod is needed to safe the motor which add in parallel with the motor??

 

i think the power diod is needed to safe the motor which add in parallel with the motor??

The diode is needed to protect the MOSFET from the flyback voltage created when the current through the motor's inductance is suddenly interrupted. If your motor is a 6 amp motor, I would use a diode rated at at least 6 amps.

 

The diode is needed to protect the MOSFET from the flyback voltage created when the current through the motor's inductance is suddenly interrupted. If your motor is a 6 amp motor, I would use a diode rated at at least 6 amps.

yes ,i reread my refrence and get what you are say about the diod protection function.thank you.