I assume that you are talking about 3 phase permanent magnet motors
Yes it has been done I don't know about ABB but Yaskawa has a setup just for that.
If I remember correctly they have a default setup for that type of motor.
Check with them.
Well apparently the ABB ACS355 drive can do it. So if you knew that, why ask the question?
An AC permanent magnet motor is going to be synchronous, yes. IPM or SPM is just how they are built, ie where the magnets are located inside of it. An SPM motor has the magnets embedded on the surface of the rotor, which provides the best efficiency. An IPM motor has the magnets buried deeper in the rotor, closer to the center, which makes them better for high speed applications, i.e. 200Hz and up, but increases the losses in the rotors. Most applications switching to AC PM motors are doing so for the increased efficiency so SPM is more common. But some people want them for high speed applications like spindles, so they use IPM.
As to whether or not you can use a servo motor with that, the answer would be yes, but you are going to pay for a servo motor and not get the added performance. The whole point of an AC PM motor is that it is less expensive than a servo but smaller than an induction motor for the same HP output.
As I understand it, the use of a PM synchronous motor with a VFD is not to get "servo-like" dynamic performance. For that you need a servo drive and motor.
The benefits of a PM motor on a VFD lie in higher efficiency and reduced steady state speed error. Eliminating motor slip removes by far the largest source of speed error in a drive/motor system.
I haven't done it myself but I have heard numerous success stories with the ACS355 on PM motors. Plus, its one of my favorite drives for middle performance applications up to 30hp so I'd be prejudiced, of course!
Originally posted by Pete.S.:
The drawback of using induction motors for simple motion control like positioning is low speed torque.
I suspect your drive is set up in sensorless vector mode or you NOT using TENV or TEBC motors. I have had a large number of applications there I have used a TENV induction motor with a drive operating in field oriented control with a suitable encoder and achieved full torque at zero speed for long periods of time. The real question is do you need to efficiency that a PM synchronous motor can give you at lower speeds. I find it hard to believe that the cost difference between a 3-phase induction motor and a 3-phase PM synchronous motor won't pay for an encoder. But I must confess I have never looked.
Keith
Yep, I just ran into that. Most of them will lose the magnetism if they get severely over heated, and once they do, there's no going back. Most PMAC motor mfrs recommend using embedded thermal sensors in the motor, such as thermistors or RTDs, rather than relying solely on the current based thermal overload in the VFD. The other thing someone warned me about, although I've never seen it, is that if you mount two PMAC motors too close to each other, or a small PMAC motor right next to a large induction motor, the magnetic fields from the other motor can demagnetize the PMAC motor's magnets. Both of these things can happen with PMDC servo motors as well, it's just that in traditional servo applications you are not usually mounting the motors in close proximity to each other or other larger motors.If you use Flux Vector control (Motor with encoder) with the correct motor selection you can run the speed down to zero at 150% torque for a very long time.
One problem I have run into with PM AC motors is that some times they lose their magnetism and the drive will try to compensate for the lose of torque by increasing the motor current and it will over heat the motor. I can tell you from experience it's a bear to trouble shoot. There is just no way to measure the magnetism in the motor when your in the field. The only fix is to either replace the motor or send it back to the factory for testing and repair.