Resolvers, Optical Encoders & Inductive Encoders

4 March 2012 Resolvers are good. Encoders are good. But which is the best? There’s only one way to find out……this article examines the strengths and weaknesses of each and also offers some alternatives. What’s a Resolver? A resolver is an electrical transformer used to measure angle of rotation. Most resolvers look rather like an electric motor - with copper windings on the stator and a machined metal rotor. The inductive coupling between the transformer’s windings varies according to angle. So, if we energize the resolver with an AC signal and measure the output from the transformer’s windings, we get an AC electrical signal whose amplitude is proportional to angle.