Sensorless Motor Speed Measurement

A new method based on current monitoring

A characteristic property of DC motors is that they can also act as generators, due to the complementary nature of Faraday’s and Lenz’s laws of magnetic induction. Thanks to this relationship, it is possible to devise a technique that measures the speed of a DC motor by monitoring the current drawn by the motor. In this article we describe a method of this sort, which can be used in a wide variety of applications.