Water/fuel ratio control using complementary filtering between valve and flowmeter feedback signals

• US 10,119,705 B2
• Filed: 04/15/2016
• Issued: 11/06/2018
• Est. Priority Date: 04/15/2016
• Status: Active Grant

• Current Assignee: Rtx Corporation
• Original Assignee: United Technologies Corporation (Rtx Corporation)
• Inventors: Thompson, Andrew B.
• Primary Examiner(s): Dao, Tuan C
• Application Number:
  US15/130,739
• Publication Number:
  US 20170299191A1
• Time in Patent Office: 935 Days
• Field of Search: None
• CPC Class Codes: F02M 25/0227 Control aspects; Arrangement of sensors; Diagnostics; Actuators
• CPC Class Codes: F23D 91/00 Burners specially adapted for specific applications, not otherwise provided for
• CPC Class Codes: F23N 1/002 using electronic means F23N1/04 - F23N1/10 take precedence
• CPC Class Codes: F23R 3/28 characterised by the fuel supply burners F23D
• CPC Class Codes: F23R 3/36 Supply of different fuels
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05D 11/132 by controlling the flow of the individual components G05D11/133 takes precedence
• CPC Class Codes: Y02T 10/12 Improving ICE efficiencies

Abstract

Systems and methods for use with water-fuel supply to industrial engines are provided. A method for controlling water supplied to an engine may include using both a desired water-fuel ratio, and a compensated fuel flow. This compensated fuel flow may be calculated by a controller-implemented complementary filter, which may include receiving, by the controller, a first signal and a second signal. The complementary filter may subtract the second signal from the first signal to create an error signal, lag the error signal to create a lagged error signal, and add the lagged error signal to the second signal to create a compensated signal. The controller may calculate a water flow request using a desired water-fuel ratio and the compensated signal.

Claims

1. A method for determining fuel supplied to an engine comprising:

receiving, by a controller, a first signal;

receiving, by the controller, a second signal, wherein a response bandwidth frequency of the first signal is less than the response bandwidth frequency of the second signal;

subtracting, by the controller, the second signal from the first signal to create an error signal;

lagging, by the controller, the error signal to create a lagged error signal using a first-order filter utilizing a time constant;

adding, by the controller, the lagged error signal to the second signal to create a compensated signal;

receiving, by the controller, a switch control signal, the compensated signal, and the second signal;

determining, by the controller, the controller implementing a switch logic, whether to send at least one of the compensated signal or the second signal;

sending, by the controller, at least one of the compensated signal or the second signal to a water-fuel ratio system.

2. The method of claim 1, wherein the first signal is received by the controller from a fuel flowmeter.

3. The method of claim 2, wherein the second signal is received by the controller from a fuel valve.

4. The method of claim 3, wherein the controller determines to send the second signal in response to at least one of the time constant comprising a value of less than or equal to zero or a reset signal being true.

5. A water-fuel control system for an engine comprising:

a controller, the controller implementing a complementary filter, configured to;

receive a first signal and a second signal, wherein a response bandwidth frequency of the first signal is less than the response bandwidth frequency of the second signal;

calculate an error signal using the first signal and the second signal;

lag the error signal to create a lagged error signal;

add the lagged error signal and the second signal to create a compensated signal;

receive a switch control signal, the compensated signal, and the second signal;

determine the controller implementing a switch logic, whether to send at least one of the compensated signal or the second signal;

calculate a water flow request, wherein the calculating is performed using a desired water-fuel ratio and the at least one of the compensated signal or the second signal; and

send the water flow request to a water control system, wherein the water flow request is used to at least one of open or close a water valve.

6. The water-fuel control system of claim 5, wherein the lagging the error signal is performed using a first-order filter utilizing a time constant.

7. The water-fuel control system of claim 6, wherein the first signal comprises a low frequency signal relative to the second signal and the second signal comprises a high frequency signal relative to the first signal.

8. The water-fuel control system of claim 7, wherein the error signal is calculated by subtracting the second signal from the first signal.

9. The water-fuel control system of claim 8, wherein the first signal is based upon a fuel flow rate determined by a flowmeter and the second signal is based upon a fuel valve position.

10. The water-fuel control system of claim 9, wherein the switch control signal is true in response to at least one of a reset signal being true or the time constant comprising a non-positive value.

11. The water-fuel control system of claim 10, wherein the switch control signal is false in response to both the reset signal being false and the time constant comprising a positive value.

12. The water-fuel control system of claim 11, wherein the controller sends the compensated signal in response to the switch control signal being false and wherein the controller sends the second signal in response to the switch control signal being true.