System and method for controlling a compression ignition engine
In some examples, a method for estimating the cetane number of a fuel includes receiving current engine operating condition measurements from a compression ignition (CI) engine using the fuel, and determining a value for a current engine performance indicator. The method further includes determining a projected engine performance indicator value for the CI engine based on the current estimated cetane number, current engine control signals and the current engine operating condition measurements. The method also includes determining that a difference between the value of the current engine performance indicator and the projected engine performance indicator value is greater than a threshold amount. If the difference is greater than the threshold amount, the method also includes determining a new estimated cetane number.
1. A method of estimating a cetane number of a fuel, comprising:
receiving, by processing circuitry, current engine operating condition measurements from a compression ignition (CI) engine using the fuel;
determining, by the processing circuitry, a value for a current engine performance indicator;
determining, by the processing circuitry, a projected engine performance indicator value for the CI engine based on a current estimated cetane number, current engine control signals and the current engine operating condition measurements;
determining, by the processing circuitry, that a difference between the value of the current engine performance indicator and the projected engine performance indicator value is greater than a threshold amount;
responsive to determining that the difference between the value of the current engine performance indicator and the projected engine performance indicator value is greater than the threshold amount, determining, by the processing circuitry, a new estimated cetane number, and
controlling, based on the new estimated cetane number, the CI engine.
2. The method of claim 1 , wherein determining the projected engine performance indicator value for the CI engine includes applying a surrogate model of the CI engine to the current estimated cetane number, the current engine control signals and the current engine operating condition measurements.
3. The method of claim 2 , wherein the surrogate model is based on a polynomial regression of values of the current engine performance indicator for values of the current cetane number, the current engine control signals and the current engine operating condition measurements.
4. The method of claim 2 , wherein the surrogate model is based on a radial basis function (RBF) modeling of values of the current engine performance indicator for values of the current cetane number, the current engine control signals and the current engine operating condition measurements.
5. The method of claim 2 , wherein the surrogate model is based on a Kriging modeling of values of the current engine performance indicator for values of the current cetane number, the current engine control signals and the current engine operating condition measurements.
6. The method of claim 1 , wherein determining the new estimated cetane number includes performing an optimization of an error function between the current engine performance indicator value and a Kriging model prediction of engine performance indicator values.
7. The method of claim 6 , wherein performing an optimization includes applying a Nelder-Mead simplex method.
8. The method of claim 6 , wherein performing an optimization includes applying a secant method.
9. The method of claim 1 , wherein the engine performance indicator is CA50.
10. The method of claim 1 , wherein the engine performance indicator is SOC.
11. The method of claim 1 , wherein the engine performance indicator is IMEP.
12. The method of claim 1 , where the threshold is a function of the current engine operating condition measurements and the estimated cetane number.
13. The method of claim 1 , wherein the current engine performance indicator value is determined based on in-cylinder pressure signals received from the CI engine.
14. The method of claim 1 , wherein the current engine performance indicator value is determined based on accelerometer signals from the CI engine.
15. The method of claim 1 , further comprising controlling, based on the new estimated cetane number, the CI engine.
16. A CI engine system, comprising:
a CI engine configured to receive engine control signals and to generate current engine operating condition measurements, the CI engine operating on a current fuel;
an engine controller connected to the CI engine, wherein the engine controller comprises processing circuitry configured to:
receive the current engine operating condition measurements from the CI engine;
determine a value for a current engine performance indicator;
determine a projected engine performance indicator value for the CI engine based on a current estimated cetane number, current engine control signals and the current engine operating condition measurements;
determine that a difference between the value of the current engine performance indicator and the projected engine performance indicator value is greater than a threshold amount;
responsive to determining that the difference between the value of the current engine performance indicator and the projected engine performance indicator value is greater than the threshold amount, determine a new estimated cetane number, and
control, based on the new estimated cetane number, the CI engine.
17. The CI engine system of claim 16 , wherein the processing circuitry is further configured to generate new engine control signals based on the new estimated cetane number and transmit the new engine control signals to the CI engine to control the CI engine.
18. The CI engine system of claim 16 , wherein to determine the projected engine performance indicator value for the CI engine the processing circuitry is further configured to applying a surrogate model of the CI engine to the current estimated cetane number, the current engine control signals and the current engine operating condition measurements.
19. The CI engine system of claim 16 , wherein to determine the new estimated cetane number the processing circuitry is further configured to perform an optimization of an error function between the current engine performance indicator value and a surrogate model prediction of engine performance indicator values.
20. A non-transitory computer-readable medium comprising instructions that, when executed, cause processing circuitry of a computing device to:
receive current engine operating condition measurements from a compression ignition (CI) engine using a fuel;
determine a value for a current engine performance indicator;
determine a projected engine performance indicator value for the CI engine based on a current estimated cetane number, current engine control signals and the current engine operating condition measurements;
determine that a difference between the value of the current engine performance indicator and the projected engine performance indicator value is greater than a threshold amount;
responsive to determining that the difference between the value of the current engine performance indicator and the projected engine performance indicator value is greater than the threshold amount, determine a new estimated cetane number, and
control, based on the new estimated cetane number, the CI engine.