What's a "RESOLVER"

[MrHorsepower]

Is this like an encoder? I just picked up some nice Servos with Resolvers?

[ynneb]

This artical should help.
http://www.renco.com/106014.htm

[ESjaavik]

A resolver is a rotating transformer with 2 secondaries that are 90 degrees out of phase with each other. It contains no active parts, it is very reliable and rugged. It works by applying a sinewave to the primary, and measuring the voltage out of the 2 secondaries. The voltage ratio of these 2 voltages makes it possible to tell where the rotor is. When rotating, the outputs will vary in a sinewave pattern as the primary couples better or worse into the secondaries.

The resolver needs a resolver interface to work. So you will need a servo drive with this capability. The resolution is determined in the drive, the resolver can support any resolution. The accuracy however is determined by the resolver, the interface and the cabling (noise). Typical resolution values are in several thousand increments/revolution internally. But the drive can usually be configured to scale this to any reasonable number of "steps/rev.". Forget Gecko, Rutex and competitors for these motors. It probably also is a 3ph BLDC and cannot be run by these even if you put in an encoder. This is because the "brushes" are absent. They are implemented as a piece of software in the drive. So the only thing that will wear on a BLDC motor with resolver, is the bearings.

[MrHorsepower]

I got nine of these things and they are brushless AC. Can you recomend a driver?

[ESjaavik]

I can reply only based on the information you give about your motors:

You need some nice brushless AC drivers with resolver interfaces.

Einar