A d.c. control circuit includes a slew-rate limiting circuit interposed between a current sensing device which detects current in a load and a control circuit, for switching on and off a thyristor controlling current through the load. The circuit limits the slew rate to a level in excess of the maximum normal current slew rate through the load.
Apparatus and method for providing digital signal processing method for controlling the speed and phase of a motor involves inputting a reference signal having a frequency and relative phase indicative of a time based signal; modifying the reference signal to introduce a slew-rate limited portion of each cycle of the reference signal; inputting a feedback signal having a frequency and relative phase indicative of the operation of said motor; modifying the feedback signal to introduce a slew-rate limited portion of each cycle of the feedback signal; analyzing the modified reference signal and the modified feedback signal to determine the frequency of the modified reference signal and of the modified feedback signal and said relative phase between said modified reference signal and said modified feedback signal; and outputting control signals to the motor for adjusting said speed and phase of the motor based on the frequency determination and determination of the relative phase.
A system for driving a motor, comprising a DC power supply source, a chopper apparatus switching voltage of the DC source to convert it into predetermined voltage and a shunt DC motor, wherein an armature and a field winding are connected in series and both ends of the series circuit are connected to the positive and negative terminals of the DC source and at the same time voltage at the junction point between the armature and the field is controlled by the chopper apparatus, is provided.
