Velocity Close Loop motor driver

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#1
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Hi

Do any one have the schematic for close loop control motor driver, velocity loop control with full bridge driver?

Scud88

"Chill out with Atmel Corp."
- Scud88.

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You'll probably want the code for the micro - assuming you expect the micro to do the speed loop or do you want an analog solution? How do you propose to detect the motor speed? How big is the motor? Why does it have to be a full bridge driver? So many questions.

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Oh Kartman again

I want the schematic for motor driver, or a chip that has the velocity control by vary its ouput current or voltage.

for example, if I use the DAC to sent a command to motor that I want it to rotate with 15% of its max. rating speed. How does the motor should know what it is rotating at 15% speed if it do not have the driver with close loop control.

I expect to have some kind of current sensing to feedback to the driver also.

Motor's size is about 12V 1.0A

And that what you're asking me about the full bridge driver I think it is easy and flexible to control motor in any direction and response time. push-pull

any suggestion?

"Chill out with Atmel Corp."
- Scud88.

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You can compute the speed by measuring time between pulses. Then simple proportional control will work... make it go a liitle faster when it's a little slow. make it go a lot faster when its really slow.

Imagecraft compiler user

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bobgardner

Are you talking about PWM driving?

I am talking about hardware close loop control.

Scud88

"Chill out with Atmel Corp."
- Scud88.

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You asked how to do closed loop speed control. To me, closed loop means you measure the speed, and control the speed. To measure speed, I would measure the time betweens revs (with a magnet and hall sensor or similar). To control the speed, you can use PWM and MOSFETS. Sorry if I caused confusion.

Imagecraft compiler user

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Oh yes, me again. You haven't answered the question about how you expect to control the motor speed. You've mentioned a DAC and PWM - do you want it done digitally or analog?
What we know:

motor 12V 1A

What we don't know:
what sort of motor -stepper? I'm assuming a permanent magnet type.
Over what speed range
What sort of speed accuracy
How you want to sense the motor speed
How do you want to control the motor speed - by the micro?

My old 5 1/4" floppy drive used a lm2917 with a couple of transistors to control the motor speed to within a couple of percent. No pwm or bridge driver needed. The motor was a permanent magnet type with a tacho winding.

If you have a circuit to control the speed in closed loop - you don't need to measure the current as you have a speed sensor. You only need to limit the maximum current to protect the motor and the drive circuit.