Re: Homegrown servo motor driver?

--- In CAD_CAM_EDM_DRO@yahoogroups.com, codeSuidae <codesuidae@...> wrote:

>
> Howdy,
>
> I'm preparing to build a small (<100W) DC motor controller for the
> purpose of learning about the problems and solutions in such products.
> While I've already done the basics (microcontroller driven h-bridge

with

> motor encoder feedback for velocity control), I have not yet tried to
> directly control position. I'm also interested in how one should go
> about choosing a PWM frequency and the benefits/trade offs of higher

and

> lower frequencies and how motor characteristics affect the decision.
>
> I wonder if anyone could direct me to some resources for expanding my
> knowledge in this area.
>
> Thanks!
> Dave K
>

The power electronics mfg's (FET's, Drivers,etc) are a rich source of
information about driving inductive loads and the trade-off of PWM
frequency vs switching loses and overshoot and EMI. The problem with
designing a generic drive is that you have to allow for such a wide
range of motors, voltages and loads that the details you will dredge
up will have to be verified in the lab using a varity of tests.
Sometimes the board layout can be critical and the higher the PWM freq
the more critical it is. As they say: "The devil is in the details".