This week engineers from Power4Flight and Northwest UAV successfully completed the latest round of integration and test with the Northwest UAV (NWUAV) NW-230 heavy fuel engine and the Power4Flight (P4F) IntelliGen Power Management Unit (PMU). Work included a range of functional and performance testing on a running engine with representative generator. With the addition of the IntelliGen, the NW-230 now offers self-starting as well as high voltage lift pack charging and low voltage power conditioning for payloads and flight critical systems. IntelliGen uses active commutation and intelligent load management to extract the maximum power available from the engine/generator at any given rpm. The available power is shared between the 28V low voltage regulator and the high voltage lift pack charger. IntelliGen uses dynamic load sharing/limiting which is user configurable and offers options for meeting the load constraints of the engine and generator as well as options for load shaping to accommodate specific mission requirements.

The testing included starting, targeted load testing over the operational rpm range, corner case testing to validate user configured limits, and thermal performance mapping with representative loads.

The sub-systems were tested independently, then together, and finally in dynamic transients. The generator was loaded to 30A directly to the high voltage load. The 28V regulator was loaded to 30A initially being supplied by the high voltage batteries. Next the generator was used to supply the 28V regulator load of 30A while also charging the 12S LiPo batteries at 12A. Lastly an RPM profile ranging between 2000rpm to over 6000rpm was used to tune the dynamic performance of the generator current management logic during fast rpm and load transients. The engineers at NWUAV were impressed by how small a device could start this engine and generate and regulate this amount of power.

Historically, fixed wing vertical takeoff and landing vehicles (fixed wing VTOLs) have not supported inflight charging of high voltage lift packs. Typically, fixed wing VTOLs carry batteries sized to meet specified margins of safety, which may include one or more go arounds and multiple takeoffs and landings. With high voltage lift pack charging the potential for physically smaller batteries becomes an option which can translate to longer endurance, larger payloads, and increased operational margin of safety.

Adding IntelliGen has other significant benefits including:

– Self-starting, connecting the commutator directly to the high voltage battery allows for onboard starting without the addition of any new hardware.

– Thrust augmentation, with a proper generator KV, thrust augmentation is possible which can be used to increase climb rate or speed for short periods of time. Again, added functionality with no additional hardware.

– SWaP, the power density of IntelliGen is unmatched when comparing its combined engine-starting, lift-battery charging and regulated outputs to other solutions for achieving all of these functions.