Hybrid powertrain coordination during a diesel particulate filter regeneration event

1. A method of controlling a vehicle powertrain during an aftertreatment regeneration event, the powertrain including an electric motor in power-flow communication with a diesel engine, the method comprising:

receiving a regeneration request;

determining if a state-of-charge of a traction battery is within a predetermined range of a target value;

initiating the regeneration event if the state-of-charge of the traction battery is within the predetermined range of the target value;

receiving an immediate torque request from a transmission control module in response to a request for an automatic gear change, wherein the immediate torque request is a momentary negative torque request that is operative to decrease the torque transmitted through an automatic transmission to facilitate the automatic gear change; and

operating the electric motor in response to the immediate torque request.

2. The method of claim 1 , wherein initiating the regeneration event includes increasing the ratio of fuel-to-air provided to the diesel engine to a level greater than a stoichiometric balance.

3. The method of claim 1 , wherein operating the electric motor in response to the immediate torque request includes operating the electric motor as a generator to produce a negative output torque.

4. The method of claim 1 , further comprising drawing-down the state-of-charge of the traction battery if the state-of-charge is above the predetermined range.

5. The method of claim 1 , further comprising regenerating the state-of-charge of the traction battery if the state-of-charge is below the predetermined range.

6. A hybrid diesel-electric powertrain comprising:

an electric motor in electrical communication with a traction battery;

a diesel engine in power-flow communication with the electric motor and with an automatic transmission, the diesel engine and electric motor configured to provide a combined torque to the automatic transmission;

an exhaust aftertreatment device in fluid communication with the diesel engine, the exhaust aftertreatment device including a lean NOx trap;

a controller in communication with the electric motor, the diesel engine, and the automatic transmission, the controller configured to:

receive a regeneration request from the exhaust aftertreatment device;

determine if a state-of-charge of the traction battery is within a predetermined range of a target value;

initiate a regeneration event if the state-of-charge of the traction battery is within the predetermined range of the target value;

receive an immediate torque request from the automatic transmission in response to a request for an automatic gear change, wherein the immediate torque request is a momentary negative torque request that is operative to decrease the torque transmitted through the automatic transmission to facilitate the automatic gear change; and

provide a torque command to the electric motor in response to the immediate torque request.

7. The hybrid diesel-electric powertrain of claim 6 , wherein the controller is configured to initiate the regeneration event by increasing a ratio of fuel-to-air provided to the diesel engine to a level greater than a stoichiometric balance.

8. The hybrid diesel-electric powertrain of claim 6 , wherein the torque command provided to the electric motor is configured to operate the electric motor as a generator to produce a negative output torque from the motor.

9. The hybrid diesel-electric powertrain of claim 6 , wherein the controller is configured to draw down the state-of-charge of the traction battery if the state-of-charge is above the predetermined range.

10. The hybrid diesel-electric powertrain of claim 6 , wherein the controller is configured to regenerate the state-of-charge of the traction battery if the state-of-charge is below the predetermined range.

11. The hybrid diesel-electric powertrain of claim 6 , wherein the exhaust aftertreatment device is configured to provide a regeneration request when the pressure drop across the aftertreatment device exceeds a threshold pressure drop.

12. The hybrid diesel-electric powertrain of claim 6 , wherein the immediate torque request includes a request for an immediate change in combined torque; and

wherein the electric motor supplies substantially all of the immediate change in combined torque in response to the immediate torque response during the regeneration event.

13. A hybrid diesel-electric powertrain comprising:

an electric motor in electrical communication with a traction battery;

a diesel engine in power-flow communication with the electric motor and with an automatic transmission, the diesel engine and electric motor configured to provide a combined torque to the automatic transmission;

an exhaust aftertreatment device in fluid communication with the diesel engine, the exhaust aftertreatment device including a lean NOx trap;

a controller in communication with the electric motor, the diesel engine, and an the automatic transmission, the controller configured to:

receive a regeneration request from the exhaust aftertreatment device;

determine if a state-of-charge of the traction battery is within a predetermined range of a target value;

initiate a regeneration event if the state-of-charge of the traction battery is within the predetermined range of the target value;

receive an immediate torque request from the automatic transmission in response to a request for an automatic gear change, the immediate torque request including a request for the combined torque to momentarily approach zero to facilitate the gear change; and

provide a negative torque command to the electric motor in response to the immediate torque request.

14. The hybrid diesel-electric powertrain of claim 13 , wherein the negative torque command provided to the electric motor is configured to operate the electric motor as a generator to produce a negative output torque from the motor.

15. The hybrid diesel-electric powertrain of claim 13 , wherein the controller is configured to draw down the state-of-charge of the traction battery if the state-of-charge is above the predetermined range.

16. The hybrid diesel-electric powertrain of claim 13 , wherein the controller is configured to regenerate the state-of-charge of the traction battery if the state-of-charge is below the predetermined range.

17. The hybrid diesel-electric powertrain of claim 13 , wherein the exhaust aftertreatment device is configured to provide a regeneration request when the pressure drop across the aftertreatment device exceeds a threshold pressure drop.

18. The hybrid diesel-electric powertrain of claim 6 , wherein the immediate torque request includes a request for an immediate change in combined torque; and

wherein the electric motor supplies substantially all of the immediate change in combined torque in response to the immediate torque response during the regeneration event.