| 摘要 |
1,083,152. Automatic tension control. WESTINGHOUSE ELECTRIC CORPORATION. April 8, 1965 [April 30, 1964], No.14940/65. Heading G3R. In a system in which elongate material is transported by an electric motor drive, deviations of a variable of the material from a desired value are automatically corrected by applying an error signal to adjust motor speed through three controllers in cascade, each of the controllers introducing an integral component, and the second and third controllers respectively introducing components dependent on motor speed and current. As described, paper strip passing between two pairs of driven pressure rolls forces a jockey roller against a spring to operate a potentiometer which thus produces a voltage dependent on the tension of the strip. This voltage is compared with an adjustable voltage, representing the desired tension, and any difference applied through three chopper-type amplifier-modifiers in cascade to control a phase-controlled semi-conductor rectifier energizing either the field circuit of a Ward Leonard set driving the second set of rolls or the armature of a D. C. motor driving the rolls so that tension is restored to the desired value. The amplifier-modifiers are provided with resistance-capacity networks to introduce integral or integral and differential components of control, with or without filtering, and are also provided with biased diode limiters. A signal dependent on the speed of the controlled rolls is derived from a tachometer generator and the difference between this signal and an adjustable reference signal applied as negative feedback to the input of the second amplifier-modifier. A signal dependent on the armature current of the controlled motor is derived from a series resistor and the difference between this signal and an adjustable reference signal applied as negative feedback through a magnetic amplifier to the input of the third amplifier-modifier. |
