Re: 3vdc motor PWM problem

On Tue, 26 Sep 2006 00:13:26 -0700, randomname wrote:
Homer J Simpson wrote:
"randomname" <randomname12345@xxxxxxxxx> wrote in message
news:1159242035.390179.269870@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

Any idea what is causing the motor to not stay at the steady rate?

Back pressure? How do you relieve the pressure?

I don't... I need the pressure so that the flow rate is lessened.

It sounds like you've built an oscillator.

The PWM comes up, the motor pumps, and you reach a head of pressure.
At this point, you need to regulate your PWM by, maybe pressure or
flow rate, not just constant-current. The motor fills up the vessel,
the pressure reaches the rated value, and the motor stalls. That
relieves the pressure, and the motor picks up speed again, until the
pressure builds up again and the motor stalls again, and so on.

You could put some kind of air buffer in the pipe, or an actual
pressure sensor and make a servo system.

Good Luck!
Rich

.

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