Method to measure rotation speed, especially for brushless dc motor; involves placing sensors at angles around rotor to transmit different binary signals and measuring time for state change

摘要

The method involves dividing a complete rotation of a rotor or rotor shaft into sectors in several angles. Sensors arranged at two or more different angles act as binary signal transmitters during the rotation to cause a state variation. The time between two or more sequential state variations of the sensors is measured to obtain a proportional rotation number. The sensors conduct a binary number, which corresponds to the common state possibilities of the sensors and are fixed by forwards or backwards rotation of the rotor in different but repeating sequences. An Independent claim is included for a device for implementing the method.