Engine system with inferential sensor
An engine system incorporating an engine, one or more sensors, and a controller. The controller may be connected to the one or more sensors and the engine. The one or more sensors may be configured to sense one or more parameters related to operation of the engine. The controller may incorporate an air-path state estimator configured to estimate one or more air-path state parameters in the engine based on values of one or more parameters sensed by the sensors. The controller may have an on-line and an off-line portion, where the on-line portion may incorporate the air-path state estimator and the off-line portion may configure and/or calibrate a model for the air-path state estimator.
1. An engine system comprising:
an engine;
one or more sensors each configured to sense a variable related to operation of the engine; and
a controller connected to the engine and the one or more sensors; and
wherein:
the controller is configured to incorporate one or more virtual sensors configured to estimate one or more parameters related to the operation of the engine by:
obtaining a differential equation representing an ordinary differential equation (ODE) model of the one or more parameters;
identifying a function from the ODE model that has a non-linear component or has a non-differentiable component;
transforming the function into a set of differential functions;
identifying a subset of the set differential functions that have a fractional form;
configuring the subset into a set of implicit algebraic equations;
producing a differential algebraic equation (DAE) model of the one or more parameters that includes the set of implicit algebraic equations and a remaining subset of the set of differential functions;
applying the variable sensed by the one or more of the sensors to the DEA model and solving the DEA model to obtain the estimate of the one or more parameters; and
the controller is configured to send control signals from the controller to adjust actuator positions of the engine based, at least in part, on the estimate of the one or more parameters.
2. The system of claim 1 , wherein the one or more virtual sensors incorporate an air-path state estimator configured to estimate one or more of an intake manifold temperature of the engine, intake manifold pressure of the engine, exhaust manifold pressure of the engine, an amount of fuel per stroke of the engine, intake manifold gas composition of the engine, in-cylinder charge mass, in-cylinder charge temperature, in-cylinder charge pressure, in-cylinder charge composition, residual mass temperature, and residual mass composition.
3. The system of claim 1 , wherein the controller is configured to incorporate two or more virtual sensors including an air-path state estimator and a NOx concentration module.
4. The system of claim 3 , wherein the air-path state estimator determines initial conditions for the NOx concentration module.
5. The system of claim 1 , wherein the controller comprises a plurality of control units.
6. The system of claim 1 , wherein the controller comprises:
an off-line portion; and
an on-line portion configured to incorporate an air-path state estimator module of a virtual sensor, the air-path state estimator module configured to estimate the one or more parameters related to the operation of the engine; and
wherein the off-line portion is configured to determine one or more differential equations for the air-path state estimator module.
7. The system of claim 6 , wherein the controller comprises a plurality of control units and a first control unit incorporates the off-line portion and a second control unit that incorporates the on-line portion and is in communication with the first control unit.
8. The system of claim 6 , wherein the off-line portion of the controller is configured to derive the ODE model into the DEA.
9. The system of claim 2 , wherein:
the engine comprises one or more turbochargers; and
the air-path state estimator solves one or more of the following:
a differential equation of pressure between components in a volume of the engine;
a differential equation of temperature between components of the engine;
a differential equation of a mass fraction of a gas species in the engine; and
a differential equation of a turbocharger speed of one or more turbochargers.
10. A method of controlling an engine with two or more modules in a controller that is in communication with the engine, the method comprising:
receiving signal values at the controller from one or more sensors sensing variables of an engine;
with a first module in the controller:
obtaining an ordinary different equation (ODE) model for a portion of the engine;
identifying a function from the ODE model that has a non-linear component or has a non-differentiable component;
transforming the function into a set of differential functions;
identifying a subset of the set differential functions that have a fractional form;
configuring the subset into a set of implicit algebraic equations;
producing a differential algebraic equation (DAE) model for the portion of the engine that includes the set of implicit algebraic equations and a remaining subset of the set of differential functions;
with a second module in the controller, calculating a quantity of a parameter produced by the engine using the DAE model based, at least in part, on the signal values from the one or more sensors; and
sending control signals from the controller to adjust actuator positions of the engine based, at least in part, on the calculated quantity of the parameter produced by the engine.
11. The method of claim 10 , further comprising sending control signals from the controller to an on-board diagnostics system configured to monitor operation of the engine.
12. The method of claim 10 , wherein the first module incorporates an air path state estimator configured to determine one or more initial conditions for determining the quantity of the parameter produced by the engine in real-time and on-line during operation of the engine.
13. The method of claim 12 , wherein the one or more initial conditions for determining the quantity of the parameter produced by the engine incorporate one or more of an intake manifold pressure of the engine, an intake manifold temperature of the engine, an exhaust manifold pressure of the engine, an amount of fuel per stroke of the engine, one or more gas compositions in an intake manifold of the engine, in-cylinder charge mass, in-cylinder charge temperature, in-cylinder charge pressure, in-cylinder charge compositions, residual mass temperatures, and residual mass compositions.
14. The method of claim 12 , wherein one or more differential equations in the first module are used to calculate the one or more initial conditions for determining the quantity of the parameter produced by the engine.
15. The method of claim 10 , wherein one or more differential equations incorporate a differential equation modeling pressure between components of an engine, a differential equation modeling temperature between components of an engine, a differential equation modeling a mass fraction of one or more gasses in an engine, and a differential equation modeling a speed of a turbocharger of an engine.
16. The method of claim 10 , wherein one or more differential equations are configured in an off-line portion of the controller by converting ordinary differential equations configured to model engine parameter values to a same or lower number of differential equations including one or more algebraic equations.
17. A method of operating an engine based, at least in part, on signal values sensed by one or more sensors in communication with the engine, the method comprising:
receiving one or more ordinary differential equations, having a first order, configured to form a first model of a parameter of an engine;
identifying a function from the one or more ordinary differential equations that has a non-linear component or has a non-differentiable component;
transforming the function into a set of differential functions;
identifying a subset of the set of differential functions that have fractions;
reconfiguring the fractions of the subset of the set of differentiable functions into implicit algebraic equations;
producing a set of differential algebraic equations, having an order lower than the first order, configured to form a second model of the parameter of the engine, wherein the set of differential algebraic equations includes the implicit algebraic equations and a remaining subset of the set of differential functions;
calculating one or more conditions of in-cylinder gas while the engine is in operation using the second model based, at least in part, on the signal values sensed by the one or more sensors; and
adjusting positions of actuators of the engine with control signals from a controller in communication with the engine in response to the calculated one or more conditions of the in-cylinder gas of the operating engine.
18. The method of claim 17 , further comprising using one or more of the calculated initial conditions of the in-cylinder gas to determine parameter values for a parameter of the operating engine.