Control without speed sensor
Implementation and industrialization of flow vector control

With an "incremental" transducer, speed is measured by counting pulses over a time interval, or by measuring the time between two pulses (at very low speeds).

In many applications, there is a strong desire to dispense with the need for a mechanical speed sensor, in order to guarantee reliable operation. Here are a few arguments in favor of sensorless control.

This is because the speed sensor is integral with the machine shaft, and held stationary in relation to the stator. It is therefore subject to all mechanical vibrations and shaft movements.