[ozzie34231]

I see advertisements for machines using Vector drives for powering spindles. These are 3 phase motors driven with VFDs.
Is this a description of the motor or the VFD or are they both of special design?
Thanks,
Ozzie

[ozzie34231]

After looking around this site I realize I should specify that I'm asking about smaller, hobby machines, (Tormach, etc.)

[Al_The_Man]

There are V/F and phase vector or flux vector drive, in the former the output of the VFD is simple variable frequency without regard as to the exact nature of rotor location, in phase vector drive, there is electronic feedback detecting the position of the rotor in order to maintain the optimum vector angle to 90°. Also known as Sensorless Vector.
There is also Vector rated motors, which purportedly have higher insulation qualities and balance etc.
Al.

[ozzie34231]

Thanks Al

[mactec54]

Thanks Al

A Vector Duty Motor normally has an Encoder, the Encoder is used for feed back to the Vector Drive, this gives the user full control of the motor, much like a servo motor, they are able to lock the rotor and position the rotor but not at the same level as a AC Servo motor is

I think Al was thinking of an Inverter Duty Motor ( Big Difference ) which are very beneficial over a regular Ac 3 Ph motor, and have a much higher performance output than a regular Ac 3 Ph motor of the same rating

When you use a drive that is Sensorless Vector it will give you some benefits with a normal Ac motor when you want to run at slower RPM the torque will be better controlled, than a normal VFD Drive does with the same motor, which does not do a good job of controlling torque at lower RPM, but be aware setting up to use too much torque on a regular Ac motor will smoke it, so auto tune (Which most Sensorless Vector Drives have ) is your friend when using a Sensorless Vector drive

So for the extra money you pay for a Sensorless Vector Drive for use with a regular Ac motor is still worth it in the long run

[ozzie34231]

Thanks Mactec54,
From what I can see here and a couple other sites, my guess is the situation is as you say in your last sentence, they are using a standard AC 3ph motor and a Sensorless Vector Drive.
I'm putting together a benchtop mill and wanted the info for that purpose.
My knee mill, (Shizuoka), has no back gear, (stripped), and a variable belt drive that goes down to about 600 RPM. I use a standard VFD on the machine and can go down quite low in RPM although the cutting I've done at very low speeds has required very little torque and has been for short periods of time.
Many thanks, I have the help I needed,
Cheers,
Ozzie