Precision ntrol of elelectrical machine speed - holds speed to within 0.2 per cent of set value using counting and anticoincidence circuit

摘要

Control circuit providing a high precision continuous control of electrical machine speed. The technique is particularly applicable to motors employed in the printing and textile industries etc. but may also be applied to dynamoes and alternators. The use of frequency synthesiser and clock sources is achieved using numeric techniques in a feedback control loop. The machine speed is initially set by a potentiometer (1) across the power supply feeding the machine through a high gain amplifier (2) actual speed, derived from some form of sensor, and required speed are fed via a counting and an anti-coincidence circuit (8) providing the required control levels from a digital to analogue convertor. A 0.01% accurate voltage to frequency convertor is used to provide the set speed data. Overall control is 0.2% of the set value.