Adaptive flow controller for use with a flow control system
First Claim
1. In 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 setpoint 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 memory; and
a processor coupled to the memory and the 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 and a deadzone of nonlinearity in order to reject noise, said setpoint error signal being the difference between the flow setpoint signal and the flow signal, wherein the processor calculates the deadzone of nonlinearity in accordance with a variance and standard deviation of the flow signal.
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Abstract
The present invention relates to an adaptive airflow control system for positioning damper systems or controlling air units utilized in an environment control system. The system is based on a conservative, fixed-gain, proportional-only feedback design to guarantee stable operation given the nonlinear behavior of flow through a valve or damper. A time-dependent deadzone of nonlinearity is used to reject measurement noise. Such a system allows a person to adjust the performance of the system by selecting a parameter that affects the tradeoff between tracking capability and noise rejection.
50 Citations
20 Claims
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1. In 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 setpoint signal from the controller, the controller comprising:
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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 memory; and a processor coupled to the memory and the 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 and a deadzone of nonlinearity in order to reject noise, said setpoint error signal being the difference between the flow setpoint signal and the flow signal, wherein the processor calculates the deadzone of nonlinearity in accordance with a variance and standard deviation of the flow signal. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A controller for use in an environment control system including an air duct including damper operatively associated with actuator, the actuator positioning the damper so that the damper provides a rate of air flow to an environment in response to an actuator control signal, the actuator being operatively coupled to the controller, the controller comprising;
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a sensor means for generating an actual flow signal representative of the rate of the air flow provided across the damper; a memory means for storing information; and a processor means coupled to the memory means and the sensor means, the processor means for cyclically receiving the actual flow signal from the sensor means and for cyclically generating the actuator control signal in response to the actual flow signal, wherein the actuator control signal is related to a desired rate for the rate of the air flow provided across the damper, the processor means calculating the actuator control signal is accordance with a setpoint error signal and a deadzone of nonlinearity in order to reject noise, said setpoint error signal being the difference between the flow setpoint signal and the flow signal, wherein the deadzone of nonlinearity is calculated in accordance with a variance and standard deviation of the actual flow signal. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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15. In a control system including a unit for providing a flow of a fluid, a controller for providing a controller output signal, and a flow sensor for providing an actual flow signal, said controller including a memory and a processor, the unit being operatively associated with the controller and controlling an amount of the flow in accordance with a controller output signal from the controller, the flow sensor being exposed to the flow provided by the unit, the flow sensor generating the actual flow signal representative of the amount of flow provided, a method of controlling the amount of the flow provided by the unit comprising steps of:
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receiving the actual flow signal from the flow sensor; determining a setpoint error signal based on the difference between a flow setpoint signal and the actual flow signal; calculating a deadzone of nonlinearity in accordance with a variance and standard deviation of the flow signal; applying the deadzone of nonlinearity to the setpoint error signal to develop the controller output signal; and providing the controller output signal to the unit. - View Dependent Claims (16, 17, 18, 19, 20)
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Specification