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US 4,143,415 AGranted
Multiple control circuit with floating setpoint
AssigneeCanadian General Electric Company Limited
InventorHerbert N. Klingbeil
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AssigneeCanadian General Electric Company Limited
InventorHerbert N. Klingbeil
Estimating the term…
A process control system providing a particular control effort function is divided into a primary control effort portion having a primary controller, and a feed back from the controlled process to the primary controller, and a secondary control effort portion having a secondary controller in controlling relation therewith, and receiving its control input from the primary controller. The secondary controller is provided with limits such that it becomes saturated in operation, thereby permitting selective overriding by the primary controller, while utilizing the secondary controller and actuators the maximum practical amount. The arrangement is suitable for use with continuously variable devices or for use with on-off (bang-bang) devices. The particular embodiments illustrated are (1) a bang-bang heater system, and (2) a continuously variable fluid flow control system.
A method of controlling a system comprising a plurality of control devices by selective on-off switching in order to achieve a desired cumulative output variable within predetermined limits, while automatically selectively controlling the extent of said on-off switching, comprising the steps of
A device control system in combination with a plurality of function providing devices, including a primary controller connected in output controlling relation with at least one primary said device, a secondary controller connected in output controlling relation with at least one secondary said deivce, the outputs of said devices being connected in mutually cumulative relation as a useful output;
A device control system for selectively controlling a plurality of function providing devices in an on-off operating mode in order to provide a close approximation to a desired cumulative output of said devices, comprising:
Dependencies are inferred from the claim text.