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How to run a DC motor at low speed w/o degrading the torque?

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vdaniel

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DC Motor at low speed

Please, how to run a DC motor at low speed without degrading the torque and
without encoder or another mechanical feedback device.

Great thanks,

Varuzhan
 

seyyah

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Re: DC Motor at low speed

Don't you want any speed feedback or estimation? If so you must have a torque reference i think and a current feedback. May be you can derive the speed from the torque as you can derive torque from speed.
 

fuzzzy

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Re: DC Motor at low speed

you can try to use PWM. this tecnique can reduce speed and maintaining the same torque because motor is supplyed by maximun voltage.
 

fekete

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Re: DC Motor at low speed

What PWM does, is to reduce the average voltage applied to the motor. As a result the torque-speed characteristic goes down. When you connect the motor to a load, that require a certain torque (actually it has it’s own torque-speed characteristic) the equilibrium point will be at a lower speed.
But you could simply reduce the applied voltage instead of PWM!
PWM has it’s advantages, depends what you have available and how complicated you want to make this thing.

You should give more details though:
What motor is it: permanent magnet, series, shunt?
What power?
How complicated is the project? Just something in your garage or you want a PC controlled driver?
 

vdaniel

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Re: DC Motor at low speed

Dear friends,

Thank you very much for all responses. Yes, current feedback, or any other case of electrical feedback I can implement easily. The same for PWM. It is not problem.
The motor which I want to use, is a standards hand-drill type motor.

Varuzhan
 

ezpcb

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Re: DC Motor at low speed

there's many voltage feed-back DC controller chips from toshiba, Renesas or Allegro. Use Microcontroller with built in PWM and ADC modules is also an option.

mike

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vdaniel

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Re: DC Motor at low speed

I need an algorithm how to control revolutions per minute without reducing
the torq at low speed. The realisation of the algorithm is not a problem for me.

Varuzhan
 

ezpcb

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Re: DC Motor at low speed

vdaniel said:
I need an algorithm how to control revolutions per minute without reducing
the torq at low speed. The realisation of the algorithm is not a problem for me.

Varuzhan
Did you mean you want to keep the torq as a constant, not the speed?

mike


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vdaniel

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Re: DC Motor at low speed

No, I want to reduce the speed without reducing the torq.

Varuzhan

Added after 2 hours 37 minutes:

No, I want to reduce the speed without reducing the torq.

Varuzhan
 

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