Adaptive algorithm for setting the proportional integral (pi) gains in lag-dominated hvacr systems
First Claim
1. A method to determine and apply PI gain constants to an HVAC PI controller when used on a lag dominated HVAC component comprising the steps of:
- recording an open loop HVAC component dynamic response;
fitting the HVAC component dynamic response to a transfer function model representative of a first order lag dominated process;
calculating the PI gain constants from the model;
entering the calculated PI gain constants into a PI control algorithm; and
running the PI control algorithm on the HVAC PI controller to control the HVAC component.
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Abstract
A method to determine and apply PI gain constants to an HVAC PI controller used to control an HVAC component includes the steps of: recording an opened loop HVAC component dynamic step response; fitting the HVAC component dynamic response to a transfer function model; calculating the PI gain constants from the model; entering the calculated PI gains into a PI control algorithm; and running the PI control algorithm on the HVAC PI controller to control the HVAC component. The inventive method can be used with an HVAC system comprising, an HVAC system component; an HVAC system component controller electrically connected to the HVAC system component to control the operation of the HVAC system component; and a PI algorithm. The PI algorithm uses PI gain constants calculated from the open loop transfer function of the HVAC system component.
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Citations
21 Claims
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1. A method to determine and apply PI gain constants to an HVAC PI controller when used on a lag dominated HVAC component comprising the steps of:
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recording an open loop HVAC component dynamic response; fitting the HVAC component dynamic response to a transfer function model representative of a first order lag dominated process; calculating the PI gain constants from the model; entering the calculated PI gain constants into a PI control algorithm; and running the PI control algorithm on the HVAC PI controller to control the HVAC component. - View Dependent Claims (4, 5, 7, 8, 9, 10, 11, 12, 13)
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- 2. The method of claim I wherein the steps of fitting the HVAC component dynamic response, calculating the PI gain constants, and entering the calculated PI gain constants are performed automatically by a computer.
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6. The method of claim I wherein fitting the HVAC component dynamic response to a transfer function model comprises fitting to a first order transfer function with a pure time delay.
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14. An HVAC system comprising:
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an HVAC system component; an HVAC system component controller electrically connected to the HVAC system component to control the operation of the HVAC system component; and a PI algorithm, the PI algorithm running on a microcomputer in the HVAC system component controller, the PI algorithm having PI gain constants, wherein the HVAC system component controller operates a closed PI loop and the PI algorithm uses PI gain constants calculated from the open loop transfer function of the HVAC system component. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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Specification