How do resolvers work

Thus, the resolver outputs provides two AC voltages whose ratio represents the absolute position of the input shaft. Even if the shaft is rotated with power removed, the resolver will report its new position value when power is restored. The principal challenge of interfacing to Resolvers is the AC nature of the signals. Capture is typically within 0. A graphical representation of the excitation signal and the sine and cosine output signals is shown below:. Here shown the high-frequency excitation voltage 2kHz - 10kHz applied to the stator primary winding.

It is now up to the RDC resolver digital converter to evaluate from this signal curve the current rotor position and the rotational speed. The calculation formulas are as follows:. From the lesson Rotary and Flow Sensors In module 3 you will learn how rotary sensors work and how to specify them for purchase.

Taught By. James Zweighaft Instructor. Jay Mendelson Instructor. Try the Course for Free. Explore our Catalog Join for free and get personalized recommendations, updates and offers. On occasion, synchros cousin to the resolver are also mentioned when explaining devices of this nature. Regardless of the names people choose to describe resolvers, their role in the world of automation remains unparalleled. Referenced as an analog sensor that is absolute over a singl e turn, the resolver was originally developed for military applications and has benefited from more than 50 years of continuous use and development.

It was not long before numerous industrial segments recognized the benefits of this rotary position sensor, engineered to withstand the punishment of a military application. Product packaging plants and stamping press lines are perfect examples of where you might find resolver based systems at work.

In typical applications, the resolver sensor feeds rotary position data to a decoder stationed in a Programmable Logic Controller PLC that interprets this information and executes commands based on the machines' position. Recent advances in technology have enabled the integration of a resolver and on-board electronics in one housing as an alternative to other types of encoders.

The Absolute Parallel and Incremental Digital versions can also be ordered with a field programmable option.