Global control of HVAC distribution system

• US 5,573,181 A
• Filed: 01/06/1995
• Issued: 11/12/1996
• Est. Priority Date: 01/06/1995
• Status: Expired due to Term

• Current Assignee: Siemens Industry Incorporated (Siemens AG)
• Original Assignee: Landis & Gyr Powers, Inc. (Landis+Gyr Group AG)
• Inventors: Ahmed, Osman
• Primary Examiner(s): Wayner, William E.
• Application Number:
  US08/369,425
• Time in Patent Office: 676 Days
• Field of Search: 236/49.3, 236/51, 236/78 D, 165/22, 62/179, 364/165
• US Class Current: 236/49.3
• CPC Class Codes: F24F 11/54 using one central controller connected to several sub-controllers
• CPC Class Codes: F24F 11/74 for controlling air flow rate or air velocity
• CPC Class Codes: F24F 11/77 by controlling the speed of ventilators
• CPC Class Codes: F24F 2110/30 Velocity
• CPC Class Codes: F24F 2110/40 Pressure, e.g. wind pressure
• CPC Class Codes: G05D 7/0688 by combined action on throttling means and flow sources G05D7/0694 takes precedence
• CPC Class Codes: Y02B 30/70 Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating

Abstract

A global control system is implemented in a heating, ventilation and air-conditioning (HVAC) distribution system. The system allows local controllers and a source controller to exchange data between one another so that optimization of control for a local component is not sacrificed for optimization of control for a source component, and vice versa. The controllers have their control process sudivided into an identification process and a control process. The identification process periodically identifies characteristics related to the component to be controlled. The control process continuously generates a control signal to be applied to the component to control the component. The control process is further subdivided into a feedforward process and a feedback process. The feedforward process utilizes the identified characteristics to generate a control signal based on calculated system variables, while the feedback generates a control signal based on measured system variables. The two control signals are then combined to control the component. The combination of the control signals produces a more accurate control signal since the effects of noise related to the measured system variables are mitigated by the combination of control signals.

Claims

1. A controller for controlling a component of a heating, ventilation and air-conditioning (HVAC) fluid distribution system, the controller comprising:

means for identifying characteristics related to the component of the HVAC fluid distribution system utilizing system variables comprising a measured static pressure and a measured flow of the fluid to produce identified characteristics of the component; and

means, operatively coupled to the means for identifying, for controlling the component based, in part, on the identified characteristics.

2. The controller of claim 1 wherein the component further comprises a damper.

3. The controller of claim 2 wherein said identified characteristics of the damper further comprise an authority (A) and a percentage of flow (%FullFlow) of the damper, and a damper control signal (Y'"'"'_d).

4. The controller of claim 3 wherein said authority (A) may be replaced by a static pressure at the inlet of the damper (P_il).

5. The controller of claim 1 wherein said means for controlling further comprises a feedforward means for generating a feedforward control signal based on the identified characteristics of the component and calculated system variables.

6. The controller of claim 5 wherein said means for controlling further comprises a feedback means for generating a feedback control signal based on measured system variables.

7. The controller of claim 6 wherein said means for controlling further comprises means for controlling the component based on a combination of said feedforward control signal and said feedback signal.

8. A controller for controlling a component implemented in a heating, ventilation and air-conditioning (HVAC) fluid distribution system, the local controller comprising:

a feedforward means for generating a feedforward control signal based on identified characteristics of the component and calculated system variables;

a feedback means for generating a feedback control signal based on measured system variables; and

means for combining the feedforward control signal and the feedback signal to achieve control of the local component.

9. The controller of claim 8 wherein the controller further comprises a local controller.

10. The controller of claim 9 wherein said feedforward means receives, from a source controller, a system variable related to an output of a source component.

11. The controller of claim 10 wherein said system variable further comprises a static pressure setpoint P_fsp at the output of the source component.

12. The controller of claim 8 wherein said feedback means implements a proportional-integral-derivative (PID) control loop based on said measured system variables to generate the feedback control signal.

13. A controller for controlling a component of a heating, ventilation and air-conditioning (HVAC) fluid distribution system, the controller comprising:

an identification means for periodically producing identified characteristics of the component to be controlled;

a feedforward means, coupled to the identification means, for generating a feedforward control signal based on control setpoints and the identified characteristics of the component;

means, coupled to the feedforward means, for generating a continuous control signal based on measured system variables; and

means for combining feedforward control signal and the continuous control signal to produce a control signal utilized to control the component.

14. The controller of claim 13 wherein said feedforward means for providing a feedforward control signal further comprises a feedforward means for generating a feedforward control signal adaptively, in real-time.

15. A controller for controlling a component of a heating, ventilation and air-conditioning (HVAC) fluid distribution system, the controller comprising:

an identification means for periodically producing identified characteristics of the component to be controlled; and

a feedforward means, coupled to the identification means, for generating a control signal based on control setpoints and the identified characteristics of the component to control the component.

16. A controller for controlling at least one fan of a heating, ventilation and air-conditioning (HVAC) fluid distribution system, the controller comprising:

means for identifying characteristics related to the fan to produce identified characteristics of the fan; and

,

means, operatively coupled to the means for identifying, for controlling the fan, based in part on the identified characteristics which further comprise a pressure setpoint (P_fsp) and a flow setpoint (Q_fsp) of air at the output of the fan, and a fan control signal (Y'"'"'_f).

17. A control system for use in a heating, ventilation and air-conditioning (HVAC) fluid distribution system, the control system comprising:

means for measuring a pressure of the fluid near a local component;

means for measuring a flow of the fluid near the local component;

a local controller for determining a flow setpoint calculated from a temperature control loop located within said local controller and for controlling the local component based on the determined flow setpoint; and

a source controller for controlling a source component of the fluid based, in part, on input related to the determined flow setpoint.

18. The control system of claim 17, wherein said source controller accepts input from a plurality of local controllers.

19. The control system of claim 17, wherein said local controller controls a variable air volume (VAV) box.

20. The control system of claim 17 further comprising:

means for measuring a pressure of the fluid near the source component; and

means for measuring a flow of the fluid near the source component.

21. The control system of claim 20, wherein said source controller controls the source component based additionally on inputs related to the measured pressure and flow near the source component.

22. The control system of claim 21, wherein said source controller calculates a total fluid flow requirement and a source component pressure setpoint requirement based on the inputs related to the measured pressure and flow near the source component and the determined flow setpoint.

23. The control system of claim 22, wherein said source controller generates a control signal for use in controlling the source component of the fluid based on the calculated total fluid flow requirement and source component pressure setpoint requirement.

24. The control system of claim 22 wherein said local controller accepts input from the source controller related to the source component pressure setpoint requirement.