MosFET amp questions

[Guest analouge]

Hi folks!

I've got a bunch of power mosfets laying around here. I've had them for many years not knowing what I should use them for. It's some leftovers from a broke company that made computer controlled wood saws. I was told when I got them that it was pretty expensive stuff, so I didn't want to get rid of them. So here it goes.

I've recently been looking for a way to control the speed of a heater motor in my car, and as I read on I came to understand that PWM was the best way of doing that. Then it's easy to read the speed with a tachometer cuircut of some kind.

So here I am trying to figure out PWM, not knowing how to build it - yet. But I figured I should start in the easy corner of the problem - the signal amplifying. I mean, how to drag up to 100 watts out of the cuircut. And then I suddenly remembered my old power mosfets. I guess I could use a couple of them.

I found out from the datasheet that they were good for 58 Amps. And that's WAY overkill, but since I have them just laying around... :P.

So I've designed a simple amplifier cuircut, and it works pretty good in my simulation, but the thing is, that in my program I haven't got the mosfet I have here besides me in the box. I guess when I'm making the speed control I just replace the part in the schematics with the mosfet I have, that is - if works.

The thing is that the datasheet says that one of the apps it can be used in is AC motor control. My best guess is that they mean AC motor PWM speed control. I don't know.

First thing I want to ask is, what's the difference between driving AC motors and DC motors. Can I use the mosfet for driving a DC motor even though it says in the datasheet it CAN be used with AC motors. I really dont know the difference between AC and DC motors when it comes to what types of transistors can drive what...

And second, can someone that knows more about this than me check out the datasheet and let me know if I can use it for DC motor PWM speed control?

THANKS A LOT!

Manufacturer: IXYS

Part#: IXFH50N20

Datasheet: http://pdf.alldatasheet.com/datasheet-pdf/view/103056/IXYS/IXFH50N20.html