Very Variable Motor Speed Control

[Rhodrons]

I need to drive a leadscrew through a drive belt connected to an AC motor. In the fast up/down mode I need to achieve a leadscrew rotation that will give about 1500mm/minute. In process mode I need to control the leadscrew rotation downwards in the range 10 to 25 mm/minute with a constnat speed +/-1% of the selected mm/minute value. The AC supply voltage drifts 405V +/-25 volts over a period of the process cycle. What will be the most successful way to configure the control and motor system so that I can achieve controlled slow speed drive and also rapid postioning at each end of the cycle?

 

[jraef]

Servo motor and control would be best for that, but how much power are you thinking of? At some point a Vector VFD might be a better choice.

"Our virtues and our failings are inseparable, like force and matter. When they separate, man is no more."
Nikola Tesla

 

[DickDV]

If the torque required is 60 ft-lbs or less, I would suggest a good sensorless vector drive coupled to a properly sized TENV (Totally Enclosed Non Vent) motor.

You will not have heating problems in the motor with that enclosure and the sensorless vector drive, if a good one, will give good speed stability at such low speeds.

Pick your power train ratio so that, at maximum machine speed your motor is operating at 90 Hz assuming a four pole or slower motor.

 

[laundry]

Hello Rhodrons
the best way to control your system is be enceder feed back ether with a vector close loop or servo.You will get good positioning to 0.01mm.
regards.

 

[DickDV]

If you are using the system to get positioning, then disregard my previous post. Positioning is a servo job, not an inverter job.

On the other hand, if the leadscrew is only for linear velocity without precise positioning, then the inverter system would be much cheaper and completely adequate.