Re: Re: Re: Chopper max voltage?

On 5 Oct, CAD_CAM_EDM_DRO@egroups.com wrote:

> My first attempt at a chopper used all discrete components running off a
> PIC, it was cheap, but as I was doing the chopping in software I couldn't
> get it above about 12Khz...

Have another look at your software.

I just built a prototype ustepper using a 4MHz PIC, a dual comparator
and a whack of high voltage FETs ( I wanted to see if my motors ran
better at higher voltages )

I was easily able to chop at over 100khz ... most of the time, the PIC
was sitting in a loop waiting.

Alan

Just thinking out loud here .. what would happen if a guy used four
comparators, two per channel, one to turn the current off ( as is done
now ), one to turn it back on. By adjusting Vref on the (new) second
comparator, a person could accommodate a wide range of motor
inductances. The effect would be to dynamically and automatically alter
switching frequency under changing conditions ... hmmm ...


--

Alan Rothenbush | The Spartans do not ask the number of the
Academic Computing Services | enemy, only where they are.
Simon Fraser University |
Burnaby, B.C., Canada | Agix of Sparta