This Forum is Dedicated For all The Object Oriented PIC Lovers .......... The concept behind OOPic is straight forward. Use preprogrammed multitasking Objects from a library of highly optimized Objects to do all the work of interacting with the hardware. Then write small scripts in Basic, C, or Java syntax styles to control the Objects. During operation, the Objects run continuously and simultaneously in the background while the scripts run in the foreground telling the objects what to do.

Tuesday, January 29, 2008

[oopic] Re: Induction Motor control using ooPIC

--- In oopic@yahoogroups.com, "john.willium" <john.willium@...> wrote:
>
> Hi Dennis,
> I want to change the speed of the induction motor according to an
> analog signal. I can give this signal to I/O line 1 to A/D conversion.
> So according to the value (0-255), I want to change the speed of the
> induction motor. For example, 100 rpm min & 1500 rpm max.
>
> The thing what I want to clarify is whether ooPIC can be used for this
> purpose. Bcoz I'm familiar with ooPIC & know this is capable of
> controlling servo motors.
>
> Regards,
> John

You are trying to make a Variable Speed Drive (VSD) and this takes a
LOT more electronics than an OOPic. Especially if the motor is more
than a tiny fraction of a HP.

You need to be able to create a square wave of appropriate voltage that
varies in frequency from 3 to 60 Hz (90 - 1800 RPM 4-pole motor). This
squarewave needs to be able to drive whatever current the motor
requires.

Normally this process goes: bring in AC, rectify it to DC, filter,
switch to motor windings.

Further, VFDs normally drive 3 phase motors although the second
reference below shows driving single phase motors.

There are references all over the place but here is one from Microchip:

http://ww1.microchip.com/downloads/en/DeviceDoc/01033B%2041.pdf and
http://ww1.microchip.com/downloads/en/AppNotes/AC%20Induction%20Motor%
2000984a.pdf

See also

http://www.aosmithmotors.com/html/motorDoctor/Understandingmotorspeed.ht
m

In the end, you won't be using an OOPic for this job.

Richard


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