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Adaptive flow controller for use with a flow control system

  • US 5,875,109 A
  • Filed: 07/03/1997
  • Issued: 02/23/1999
  • Est. Priority Date: 05/24/1995
  • Status: Expired due to Term
First Claim
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1. An environment control system including an air unit for providing air flow to an environment, the air unit being operatively associated with a controller and controlling an amount of the air flow in accordance with a flow set-point signal from the controller, the controller comprising:

  • a flow sensor exposed to the air flow provided by the unit, the flow sensor generating a flow signal representative of an amount of the air flow provided to the environment;

    a processor connected to the flow sensor, the processor configured to cyclically receive the flow signal and generate a controller output signal in response to the flow signal and the flow setpoint signal, the controller output signal being provided to the air unit to cause the air unit to provide the amount of the air flow represented by the flow setpoint signal, the processor calculating the controller output signal in accordance with a setpoint error signal, a proportionality constant, and a deadzone of nonlinearity, whereby the processor calculates the deadzone of nonlinearity in accordance with a variance of the flow signal;

    the processor switching the controller between a first operating mode and a second operating mode in response to a set of conditions associated with the flow setpoint signal, said first operating mode being a default mode;

    wherein the processor changes the proportionality constant stepwise from a first predetermined constant to a second predetermined constant thereby instantaneously switching the environment control system from the first operating mode to the second operating mode in response to a predetermined change in the setpoint signal for closely tracking changes in the setpoint error signal; and

    wherein the processor exponentially changes the proportionality constant from the second predetermined constant to the first predetermined constant thereby gradually switching the environment control system from the second operating mode to the first operating mode in response to a predetermined change in the flow signal for normally tracking changes in the setpoint error signal.

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