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Best way to control precisely the power of the electric motor DC/AC ? Answered

What  is  the  best    way  to   control    precisely the  power  of  the  electric  motor  DC/AC ? I am  thinking  of  building  electric  resistance  cable exercising   machine.?


What do you mean by  "electric resistance cable exercising machine"?
Consider using fans instead (aerodynamic load)


Imagine I can place an electric winch instead of plates in the cable machine in the gym. Then I can connect the cable to the electric winch. If I could find a way to precisely control the torque of that winch i could replace the heavy wight plates with an electric winch/motor. So no, aerodynamic resistance at this point is not applicable. But thanks anyway.

This is silly because gravity is free.
You'll pay-for electricity to balance your physical output rather than lift weights; why?


Because I could place a winch in many positions depending on the metal frame you build. Have you seen the machine that you could move the plates stack. Instead you need many machines to do the whole workout. I would need only one machine with changing the position of the winch. Cost of the electricity is negligible.

My question was not about the machines that use gravity as the resistance. It was how to control the current drawn by the electric motor.

With a motor controller.

Please tell me more details. Where i could find the controller that would control the torque of the electric winch/motor. I am interested in particular in the website and the model. Thanks.

Depends on the motor being used and how much power it needs. But you'll only be able to control the speed of the motor. What you want is magnetic resistance. Controlling the power to an electromagnet against a spinning disk that is tied to the weight lifting pules will give you the resistance your looking for. How to best control that and how that will translate to equivalent weights will be a matter of trial and error on your part.

Are you saying i cannot control the torque of the motor, only a speed ? I would prefer to use electric winch as the resistance rather than the magnetic one.

You control the torch with gears but that's not what you need. Your not going to be able to fight against the winch and if you do get it low enough that you can fight the wench you will burn it out. Same goes for any motor. If you stop the motor and force it in the opposite direction you will wear ti out very quickly. You want to use magnetic resistance like i mentioned above. Magnetic resistance is home you vary the resistance on modern cross trainers and exercise bikes. Or you can go old school and use a set of bike breaks to add resistance but then you would have to release the break on your down strokes.

Why would I burn the motor out if I can limit the current it draws (torque). A motor gets burnt b/c it draws too much current - so it overheats. Unless I am something missing here in this puzzle.

When you fight the motor it draws more current and will burn out.

The whole point of this discussion is to find a way to limit a current drawn by the motor. This way you can fight a motor without burning it. If I could limit current precisely I could control the torque.