METHOD AND CIRCUITRY TO GENERATE SPEED INFORMATION IN A CONTROL CIRCUIT OF A BRUSHLESS DC MOTOR TO CONTROL IT BY MEANS OF A DIGITAL CONTROL DEVICE

摘要

The invention concerns a speed-control system, method and circuit for carrying out the system, for a brushless direct-current motor using a digital servo loop, specifically an economical and simple means of generating precise information relating to speed of rotation that can also be converted into digital words that can be processed by a microprocessor or by wired components in normal digital switching circuits like counters, gates, adders and subtractors, flip-flops, multipliers, memories, etc. The motor has a permanent-magnet rotor. The voltage at at least one of the stator windings is employed to generate speed information. This is converted by means of a threshold detector into a rectangular wave that can be further processed by the circuit.