What is a resolver?

A resolver is an electrical transformer used to measure the angle of rotation. Many resolvers look somewhat like an electric motor comprising of copper windings on the stator and a machined metal rotor.

Types of resolver

There are a variety of types of resolver:

Resolvers have an established reputation for accuracy and reliability and are often the automatic choice for safety related applications. The use of copper windings and metal elements means that resolvers are robust, but also heavy, bulky and expensive.

In recent years, a new generation of device has become popular – the inductive encoder. Inductive encoders, such as IncOders made by Celera Motion, use the same physics as a resolver but are less costly, lighter, more compact and accurate. Rather than the traditional resolver’s copper windings, inductive encoders use printed circuit boards as their main element.

Strengths and weaknesses of a resolver

StrengthsWeaknesses
Reliable, robust, accurate, long life, tolerant to misalignmentBulky, heavy, expensive, needs skilful specification and implementation