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First of all, I'm an undergrad student of Mechanical Engineering, and I'm working on a project where the main component is a type of linear actuator which I'm going to design. I will use a roller screw mechanism for the actuator, and it's main job will be to compress some material. One of the specifications for this project is that the electric motor needs to deliver between 2-3 horsepower, and still be precise enough to control the speed of the linear actuator (between 0.5 and 2 mm/s). Which kind of electric motor should I use for this project? I've thought about using a commom electric motor like this one (link) with a reductor. Would that be enough? I have little background in electrical engineering, so any insights would be helpful.

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  • \$\begingroup\$ If you used a position feedback system why would you need the motor to be precise? Why is there a range of linear speeds and what force is required at the linear speed? \$\endgroup\$ – Andy aka Nov 18 '16 at 22:42
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You have selected a 3-phase induction motor. To control the speed, you will also need a variable frequency drive (VFD). I suppose "Apto ao uso com inversor de frequência até 575V" refers to the VFD. Depending on the capabilities of the selected VFD, that combination will probably provide what you need.

You need to determine the range of required motor speeds required and amount of deviation from set speed that can be tolerated. With a good VFD, the motor can be expected to deliver the rated torque for full speed at reduced speeds down to nearly zero speed. The motor may need a separately driven cooling fan to avoid overheating if operated at below perhaps 1/2 or 1/3 speed for longer than a few minutes. You would need to get the details for that from the motor manufacturer. You can expect a good VFD to hold the speed at the set speed regardless of load change with a deviation of about 0.1 to 0.5% of full speed. Get details from VFD manufacturer.

You can probably find a VFD that will allow the motor to deliver rated torque while stalled and the motor will probably tolerate that for some period of time depending on cooling. Get details on stalled torque deviation from VFD manufacturer.

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  • \$\begingroup\$ Thank you for the information. As I said, I don't have experience with larger motors and VFD (as my background is in mechanical), but I've toyed with small arduino projects. Would assembling this motor with the VFD require a lot of technical knowledge in electrical engineering, or it's something which I could learn easily? \$\endgroup\$ – Vinicius Nov 19 '16 at 1:00
  • \$\begingroup\$ Selecting the VFD and verifying that the equipment meets your needs is probably the most difficult part. The input power to the VFD needs to be wired from a circuit breaker or disconnect switch and fuses. The VFD manual may have instructions about that. You will probably want a sensorless-vector, direct-torque-control or equivalent VFD. You should probably identify a VFD with a good reputation and support in your area then download the manual to see what is involved. \$\endgroup\$ – Charles Cowie Nov 19 '16 at 2:07
  • \$\begingroup\$ You should probably look at this:ecatalog.weg.net/files/wegnet/… \$\endgroup\$ – Charles Cowie Nov 19 '16 at 2:40
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    \$\begingroup\$ If you are asking if an Arduino or PLC can substitute for a VFD, the answer is no. An Arduino could be used as the control section of a VFD, but additional circuitry would be required for the power section. A project like that would be quite challenging. Either an Arduino or PLC could be used to give a VFD a speed command based on process requirements depending on what aspect of the process determines the speed requirement. How to do that is far beyond the original question about selecting a motor. \$\endgroup\$ – Charles Cowie Nov 19 '16 at 16:10
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    \$\begingroup\$ Yes, I thought about using an arduino or PLC to send speed commands to the VFD. The ideia is that I could control the speed on a computer, but I do realize that this is beyond the scope of the original question. \$\endgroup\$ – Vinicius Nov 19 '16 at 17:04

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