US 2003/0125819 A1Published application

Control loop status maintainer for temporarily opened control loops

AssigneeTexas Instruments Incorporated

InventorKurt F. Hesse

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Abstract

A system provides primary and alternate control circuits to a controlled system through an output port. A monitoring circuit that monitors a parameter of the controlled system selects the control methodology. The primary control circuit, consisting of a primary active part and a regulator, and an alternate control circuit receive feedback from the controlled system. A switching mechanism, controlled by an output of the monitoring circuit, connects the appropriate control circuit to the controlled system and switches internal connections as needed. During alternate mode, a simulator of the controlled system as driven by the primary active control circuit provides an output representative of the output of the regulator that would cause the current output of the controlled system if the system were in primary mode. This simulator output is used when transitioning back to primary mode to minimize transients in the output of the controlled system.

Claims10

Dependent claims

An apparatus to provide multiple-mode control to a controlled system through an output port comprising:

a primary control circuit, having a regulator portion driving an active controlling portion, receiving a feedback output from said controlled system at an input of said regulator portion, an output of said primary control circuit connectable to said output port;
an alternate control circuit receiving said feedback output, an output of said alternate control circuit connectable to said output port;
a monitoring circuit generating a mode indication of one of a primary mode and an alternate mode in response to a monitored parameter of said controlled system;
a selecting mechanism disposed between said output port and said outputs of said primary control circuit and said alternate control circuit, said selecting mechanism controlled by said mode indication of said monitoring circuit;
a transient management system operative to simulate said feedback output of said controlled system when driven by said active controlling portion, said transient management system having an input connected to an output of said regulator portion when said primary control circuit is connected to said controlled system, said input connected to a transient management system feedback output otherwise;
and
a compensation network including a first terminal connected to said feedback output and a second terminal connected to a switch providing connection to an output of said regulator portion in primary mode and to said transient management feedback output in alternate mode, a capacitance present in said compensation network, wherein an output of said controlled system remains approximately steady when the multi-mode control system changes from alternate to primary control mode.

4 more elements

In a system in which a control output drives a controlled system having a monitor point connected back to a feedback input, and a compensation network incorporating a storage element connected between said feedback input and a compensation output, a method of sharing said control output between two control circuits to minimize transients on an output of said controlled system as control is switched between said two control circuits in response to a mode control signal, the method comprising:

in response to said mode control signal indicating a primary mode, connecting said control output to a first control circuit output, connecting an error amplifier output to said compensation output, connecting said error amplifier output to a simulator circuit input, wherein said simulator circuit simulates the operation of said controlled system as driven by said first control circuit, setting a sample and hold circuit to sample and connecting an output of said simulator circuit to a sample and hold circuit input;
in response to said mode control signal changing to indicate a secondary mode, switching said control output to a second control circuit output, switching said sample and hold circuit to hold mode, connecting an output of said sample and hold circuit to a non-inverting input of a simulator error amplifier, switching said simulator output to an inverting input of said simulator error amplifier, and connecting an output of said simulator error amplifier to both said compensation output and said input to said simulator;
and
in response to said mode control signal changing to indicate said primary mode, changing said output of said error amplifier to assume a correct voltage to minimize transient disturbances in said output of said controlled system, wherein said change is accomplished by controlling the offset stored in said compensation network during operation in said secondary mode.

1 more element

Dependencies are inferred from the claim text.