At 11:41 AM 5/23/2003 -0400, you wrote:
>Hey all,
>         I've been looking around the net for a variable speed motor
>controller for a 2HP 120Vdc motor and have found they are rather
>expensive.
>
>I decided I might try making the controller myself, but I'm thinking
>the controllers must be expensive for a reason.  Anyone know why?

I don't think they are particularly expensive for an industrial/
commercial product.

>I've attached a rather simple design to this message and would
>appreciate any comments.
>
>I have yet to design the inrush current limiter, but will probably use
>an active mosfet design similar to the following:
>https://www.onsemi.com/pub/Collateral/AN1542-D.PDF page 2.

In theory, should work. Keep in mind that the DC motor is a generator and
feed power back into the circuit under some conditions. Most commercial
controls have some kind of feedback to improve torque at low speed,
either IR compensation or tachometer feedback or back-EMF feedback.

An SCR controller might be cheaper and emit less electrical noise than
your PWM.

Best regards,

Spehro Pefhany --"it's the network..."            "The Journey is the reward"
speff@interlog.com             Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog  Info for designers:  http://www.speff.com

--
http://www.piclist.com hint: The list server can filter out subtopics
(like ads or off topics) for you. See http://www.piclist.com/#topics