Hybrid electric drive systems for unmanned aircraft systems

1 . A hybrid powerplant, comprising:

a main power bus;

an engine;

a generator coupled to the engine, the generator in electrical communication with the main power bus;

an energy storage coupled to the main power bus in parallel to the engine;

an electrical switch disposed electrically between the main power bus and the energy storage; and

a controller in electrical communication with the electrical switch,

wherein the controller is configured to:

command the electrical switch to close in response to determining a power demand of an electrical load is greater than a maximum power output for the generator;

receive a power demand for an electrical load that is greater than a current power demand;

command the electrical switch to transition from an open position to a closed position to electrically couple the energy storage to the main power bus;

command the electrical switch to close in order to facilitate the energy storage to provide additional current capacity;

command the engine to accelerate to a second speed from a first speed and a second engine torque from a first engine torque correlated with the power demand; and

command the electrical switch to transition from the closed position to the open position to disconnect the energy storage from the main power bus.

2 . The hybrid powerplant of claim 1 , wherein the hybrid powerplant has a main operating mode and an alternate operating mode, wherein in the main operating mode, the controller is configured to open the electrical switch and the engine remains in electrical communication with the main power bus, and wherein in an alternate operating mode, the controller is configured to close the electrical switch to electrically couple the energy storage to the main power bus.

3 . The hybrid powerplant of claim 1 , wherein the hybrid powerplant is configured to provide a variable voltage output to an electrical load through the main power bus.

4 . The hybrid powerplant of claim 1 , wherein the controller is further configured to determine when the engine is operating at the second speed and the second engine torque prior to commanding the electrical switch to transition from the closed position to the open position.

5 . A generator management unit for a hybrid powerplant, the generator management unit comprising:

a processor; and

a tangible, non-transitory computer-readable storage medium having instructions stored thereon that, in response to execution by the processor, cause the processor to perform operations comprising:

receiving, via the processor, a power demand for an electrical load that is greater than a current power demand being provided to the electrical load, the

current power demand being provided by a generator operably coupled to an engine, the generator providing a first voltage, wherein the engine operates at a first speed and a first engine torque to produce the current power demand;

commanding, via the processor, an electrical switch to transition from an open position to a closed position to electrically couple an energy storage to a main power bus, the main power bus in electrical communication with the electrical load in parallel to the energy storage; and

in response to the energy storage becoming electrically coupled to the main power bus, achieving the power demand,

commanding, via the processor, the engine to accelerate to a second speed and a second engine torque correlated with the power demand; and

commanding, via the processor, the electrical switch to transition from the closed position to the open position in response to the engine operating at the second speed and the second engine torque.

6 . The generator management unit of claim 5 , wherein the power demand exceeds a generator maximum power output of the generator.

7 . The hybrid powerplant of claim 1 , wherein a first output voltage of the generator is configured to vary below a second output voltage of the energy storage.

8 . A generator management unit for a hybrid powerplant, the generator management unit comprising:

a processor; and

a tangible, non-transitory computer-readable storage medium having instructions stored thereon that, in response to execution by the processor, cause the processor to perform operations comprising:

receiving, via the processor, a power demand for an electrical load that is greater than a current power demand being provided to the electrical load, the

current power demand being provided by a generator operably coupled to an engine, the generator providing a first voltage;

commanding, via the processor, an electrical switch to transition from an open position to a closed position to electrically couple an energy storage to a main power bus, the main power bus in electrical communication with the electrical load in parallel to the energy storage;

in response to the energy storage becoming electrically coupled to the main power bus, achieving the power demand;

determining, via the processor, a second power demand for charging the energy storage;

commanding, via the processor, the engine to provide a second engine speed and a second engine torque correlated with a total power demand, the generator configured to power the electrical load and charge the energy storage in response to the engine providing the second engine speed and the second engine torque; and

commanding the electrical switch to transition from the closed position to the open position in response to determining the energy storage is charged.