Airflow control systems and methods using model predictive control

1. An engine control system for a vehicle, comprising:

a torque requesting module that generates a first torque request for a spark ignition engine based on driver input;

a torque conversion module that converts the first torque request into a second torque request;

a setpoint control module that generates air and exhaust setpoints for the spark ignition engine based on the second torque request;

a vacuum requesting module that requests an amount of vacuum within an intake manifold of the engine,

wherein the setpoint module selectively adjusts at least one of the air and exhaust setpoints based on the amount of vacuum requested;

a model predictive control (MPC) module that identifies sets of possible target actuator values based on the air and exhaust setpoints, that generates predicted parameters based on a model of the spark ignition engine and the sets of possible target actuator values, respectively, that selects one of the sets of possible target actuator values based on the predicted parameters, and that sets target actuator values based on the possible target actuator values of the selected one of the sets; and

a throttle actuator module that controls opening of a throttle valve based on a first one of the target actuator values.

2. The engine control system of claim 1 wherein the vacuum requesting module requests the amount of vacuum within the intake manifold of the engine relative to an ambient pressure.

3. The engine control system of claim 1 wherein the vacuum requesting module generates the request in response to actuation of a brake pedal.

4. The engine control system of claim 1 wherein the vacuum requesting module generates the request when an amount of fuel vapor within a fuel vapor canister is greater than a predetermined value.

5. The engine control system of claim 1 wherein the vacuum requesting module generates the request in response to a second request to perform an evaporative emissions system fault diagnostic.

6. The engine control system of claim 1 further comprising a cylinder actuator module that enables opening of intake and exhaust valves of a target number of cylinders,

wherein the setpoint module selectively increases the target number based on the amount of vacuum requested.

7. The engine control system of claim 1 wherein the setpoint module determines a maximum torque output of the engine with the requested amount of vacuum within the intake manifold and selectively requests a gear shift of a transmission to a lower gear when the maximum torque output of the engine is less than a predetermined torque.

8. The engine control system of claim 1 further comprising:

a boost actuator module that controls opening of a wastegate based on a second one of the target actuator values;

an exhaust gas recirculation (EGR) actuator module that controls opening of an EGR valve based on a third one of the target actuator values; and

a phaser actuator module that controls intake and exhaust valve phasing based on fourth and fifth ones of the target actuator values.

9. The engine control system of claim 1 wherein the MPC module selects the one of the sets of possible target actuator values based on comparisons of the air and exhaust setpoints with the predicted parameters, respectively.

10. The engine control system of claim 9 wherein the MPC module determines costs for the sets of possible target actuator values based on the comparisons of the air and exhaust setpoints with the predicted parameters, respectively, and selects the one of the sets of possible target actuator values based on the costs.

11. An engine control method for a vehicle, comprising:

generating a first torque request for a spark ignition engine based on driver input;

converting the first torque request into a second torque request;

generating air and exhaust setpoints for the spark ignition engine based on the second torque request;

requesting an amount of vacuum within an intake manifold of the engine;

selectively adjusting at least one of the air and exhaust setpoints based on the amount of vacuum requested;

using a model predictive control (MPC) module:

identifying sets of possible target actuator values based on the air and exhaust setpoints;

generating predicted parameters based on a model of the spark ignition engine and the sets of possible target actuator values, respectively;

selecting one of the sets of possible target actuator values based on the predicted parameters; and

setting target actuator values based on the possible target actuator values of the selected one of the sets; and

controlling opening of a throttle valve based on a first one of the target actuator values.

12. The engine control method of claim 11 further comprising requesting the amount of vacuum within the intake manifold of the engine relative to an ambient pressure.

13. The engine control method of claim 11 further comprising generating the request in response to actuation of a brake pedal.

14. The engine control method of claim 11 further comprising generating the request when an amount of fuel vapor within a fuel vapor canister is greater than a predetermined value.

15. The engine control method of claim 11 further comprising generating the request in response to a second request to perform an evaporative emissions system fault diagnostic.

16. The engine control method of claim 11 further comprising:

enabling opening of intake and exhaust valves of a target number of cylinders; and

selectively increasing the target number based on the amount of vacuum requested.

17. The engine control method of claim 11 further comprising:

determining a maximum torque output of the engine with the requested amount of vacuum within the intake manifold; and

selectively requesting a gear shift of a transmission to a lower gear when the maximum torque output of the engine is less than a predetermined torque.

18. The engine control method of claim 11 further comprising:

controlling opening of a wastegate based on a second one of the target actuator values;

controlling opening of an exhaust gas recirculation (EGR) valve based on a third one of the target actuator values; and

controlling intake and exhaust valve phasing based on fourth and fifth ones of the target actuator values.

19. The engine control method of claim 11 further comprising selecting the one of the sets of possible target actuator values based on comparisons of the air and exhaust setpoints with the predicted parameters, respectively.

20. The engine control method of claim 19 further comprising:

determining costs for the sets of possible target actuator values based on the comparisons of the air and exhaust setpoints with the predicted parameters, respectively; and

selecting the one of the sets of possible target actuator values based on the costs.