Integrated control and fault detection of HVAC equipment
First Claim
1. In a finite state machine controller for a heating, ventilating and air conditioning (HVAC) system for a building, wherein the state machine controller has a plurality of states and makes transitions between states upon the occurrence of predefined conditions, a fault detection method comprising:
- gathering operational data regarding performance of the HVAC system;
evaluating the operational data against predefined criteria for a current state in which the finite state machine controller is operating or for a given transition which has occurred; and
based on the evaluating step determining whether an fault condition exists.
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Abstract
Fault detection is implemented on a finite state machine controller for an air handling system. The method employs data, regarding the system performance in the current state and upon a transition occurring, to determine whether a fault condition exists. The fault detection may be based on saturation of the system control or on a comparison of actual performance to a mathematical model of the air handling system. As a consequence, the control does not have to be in steady-state operation to perform fault detection.
287 Citations
24 Claims
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1. In a finite state machine controller for a heating, ventilating and air conditioning (HVAC) system for a building, wherein the state machine controller has a plurality of states and makes transitions between states upon the occurrence of predefined conditions, a fault detection method comprising:
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gathering operational data regarding performance of the HVAC system;
evaluating the operational data against predefined criteria for a current state in which the finite state machine controller is operating or for a given transition which has occurred; and
based on the evaluating step determining whether an fault condition exists. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12)
comparing the performance of the HVAC system to a mathematical system model of the HVAC system to derive a residual; and
declaring a fault condition in response to the residual.
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6. The method as recited in claim 5 wherein the residual has a numerical value and the fault condition is declared in response to the magnitude of the numerical value.
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7. The method as recited in claim 5 wherein the fault condition is declared in response to detecting a predefined change in the residual.
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8. The method as recited in claim 5 wherein the fault condition is declared in response to detecting an abrupt change in the residual.
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9. The method as recited in claim 5 wherein the residual is a function of at least two of a temperature of air outside the building, a temperature of air supplied by the HVAC system, temperature of air returned to the HVAC system from a room of the building, and a temperature of a mixture of air from outside the building and the air returned to the HVAC system.
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10. The method as recited in claim 5 wherein the residual is derived from a mass balance for dry air entering and leaving a space of the building controlled by the HVAC system.
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11. The method as recited in claim 5 wherein the residual is a function of a fraction of outdoor air utilized by the HVAC system.
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12. The method as recited in claim 5 wherein the residual is derived from an energy balance for air entering and leaving the HVAC system.
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13. In a finite state machine controller for a heating, ventilating and air conditioning (HVAC) system for a building, wherein the state machine controller has a plurality of states and makes transitions between states upon the occurrence of predefined conditions, a fault detection method comprising:
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gathering operational data regarding performance of the HVAC system in the given state;
detecting when control of the HVAC system becomes saturated in a given state wherein such saturation can not be overcome by a transition to another state; and
issuing a signal that indicates an occurrence of a fault condition. - View Dependent Claims (14)
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15. In a finite state machine controller for a heating, ventilating and air conditioning (HVAC) system for a building, wherein the state machine controller has a plurality of states and makes transitions between states when predefined conditions exist, a fault detection method comprising:
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gathering operational data regarding performance of the HVAC system in the given state;
occasionally comparing performance of the HVAC system to a model of HVAC system performance; and
declaring a fault condition in response to results of the comparing. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24)
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Specification