Locomotive control system having thermal management

1. A control system for a machine having an engine, a first alternator, a second alternator, and an aftertreatment system, the control system comprising:

a sensor associated with the aftertreatment system and configured to determine a temperature of exhaust passing through the aftertreatment system; and

a controller in communication with the sensor and connectable to the first and second alternators, the controller being configured to:

determine a speed of the machine;

determine an available power output of the first alternator;

determine a load increase of the engine needed to raise the temperature of the exhaust to an operating temperature of the aftertreatment system;

selectively connect the first alternator to a power consumer to achieve the load increase when the available power output of the first alternator is greater than the load increase;

selectively connect the second alternator to the power consumer to achieve the load increase when the available power output of the first alternator is less than the load increase; and

selectively connect at least one of the first and second alternators to the power consumer when the speed of the machine is above a threshold speed.

2. The control system of claim 1 , wherein the controller is further configured to:

determine an available power output of the second alternator; and

selectively connect the second alternator to the power consumer to achieve the load increase when the available power output of the second alternator is greater than the load increase.

3. The control system of claim 1 , wherein:

the power consumer is configured to receive electrical energy from at least one of the first and second alternators and to dissipate heat energy; and

the control system further includes an energy recovery unit associated with the power consumer and configured to convert the heat energy dissipated by the power consumer into electrical energy when the first or second alternator is connected to the power consumer.

4. The control system of claim 1 , wherein:

the control system further includes a throttle selector movable from an idle position through a range to a maximum position to affect a speed of the engine; and

the controller is configured to selectively connect the at least one of the first and second alternators to the power consumer only when the throttle selector is moved to a position below a threshold position.

5. The control system of claim 4 , wherein:

the control system further includes an auxiliary power source that has an output capacity less than the engine; and

the controller is further configured to:

track a time elapsed after the throttle selector is moved to the idle position; and

selectively shut down the engine and activate the auxiliary power source when the elapsed time exceeds an elapsed time limit.

6. The control system of claim 5 , wherein the controller is further configured to selectively shut down the engine only when the temperature of the exhaust is below a threshold temperature for limiting a temperature of the aftertreatment system.

7. The control system of claim 5 , wherein the controller is further configured to:

determine a load generated by one or more power consumers; and

selectively shut down the engine only when the load generated by the one or more power consumers is less than an output capacity of the auxiliary power source.

8. The control system of claim 7 , wherein:

the one or more power consumers includes a compressed air system associated with braking of the machine; and

the controller is further configured to:

determine a pressure of the compressed air system; and

selectively shut down the engine only when the pressure of the compressed air system is above a minimum activation pressure.

9. The control system of claim 5 , wherein the auxiliary power source includes at least one of an engine-powered generator and a battery bank.

10. A method of operating a machine having an engine, a first alternator, a second alternator, and an aftertreatment system, the method comprising:

receiving a throttle selection from an operator;

determining a speed of the machine;

directing exhaust away from the engine through the aftertreatment system;

determining a temperature of the exhaust;

determining an available power output of the first alternator;

determining an engine load increase needed to raise the temperature of the exhaust to an operating temperature of the aftertreatment system;

selectively connecting the first alternator to a power consumer to achieve the engine load increase when the available power output of the first alternator is greater than the engine load increase;

selectively connecting the second alternator to the power consumer to achieve the engine load increase when the available power output of the first alternator is less than the engine load increase; and

selectively connecting at least one of the first and second alternators to the power consumer when the throttle selection is above a threshold selection and the speed of the machine is above a threshold speed.

11. The method of claim 10 , further including:

determining an available power output of the second alternator; and

selectively connecting the second alternator to the power consumer to achieve the load increase only when the available power output of the second alternator is greater than the load increase.

12. The method of claim 10 , further including converting heat energy dissipated by the power consumer into electrical energy when at least one of the first and second alternators is connected to the power consumer.

13. The method of claim 10 , wherein:

the machine further includes an auxiliary power source; and

the method further includes:

receiving a throttle selection from an operator;

tracking a time elapsed when the throttle selection is below a threshold selection; and

selectively shutting down the engine and activating the auxiliary power source when the elapsed time exceeds a time limit.

14. The method of claim 13 , further including:

determining a load generated by one or more power consumers; and

selectively shutting down the engine only when the load generated by the one or more power consumers is less than an output capacity of the auxiliary power source.

15. The method of claim 13 , further including selectively shutting down the engine only when the temperature of the exhaust is below a threshold temperature for limiting a temperature of the aftertreatment system.

16. The method of claim 14 , wherein:

the one or more power consumers includes a compressed air system associated with braking of the machine; and

the method further includes:

determining a pressure of the compressed air system; and

selectively shutting down the engine only when the pressure of the compressed air system is above a minimum activation pressure.

17. The method of claim 13 , wherein activating the auxiliary power source includes activating at least one of an engine-powered generator and a battery bank.

18. A locomotive, comprising:

an engine;

a first alternator driven by the engine;

a second alternator driven by the engine;

an aftertreatment system connected to receive exhaust from the engine;

a sensor associated with the aftertreatment system and configured to determine a temperature of exhaust passing through the aftertreatment system;

a throttle selector movable from an idle position through a range to a maximum position to affect a speed of the engine;

one or more power consumers connectable to at least one of the first and second alternators;

an auxiliary power source connectable to the one or more power consumers; and

a controller in communication with the sensor and connectable to the first and second alternators, the controller being configured to:

determine an available power output of the first alternator;

determine an available power output of the second alternator;

determine a load increase of the engine needed to raise the temperature of the exhaust to a threshold temperature;

selectively connect the first alternator to at least one of the one or more power consumers to achieve the load increase when the available power output of the first alternator is greater than the load increase; and

selectively connect the second alternator to the at least one of the one or more power consumers to achieve the load increase when the available power output of the first alternator is less than the load increase and the available power output of the second alternator is greater than the load increase;

track a time elapsed when the throttle selector is moved to the idle position;

determine a load generated by one or more power consumers; and

selectively shut down the engine and activate the auxiliary power source only when the load generated by the one or more power consumers is less than an output capacity of the auxiliary power source and the temperature of the exhaust passing through the aftertreatment system is below a threshold temperature for limiting a temperature the aftertreatment system.