Typical UAV generator system
UAV Generators
Minimising the mass that must be carried by an airframe is central to maximising performance and range. Batteries can constitute a significant part of the overall mass of small to medium-sized UAVs, and so storing the necessary electrical energy in an alternative form is one way of reducing the battery mass.
The gravimetric energy density of liquid hydrocarbon fuels remain more than an order of magnitude better than the best battery technology (12 kWh/kg for aviation fuel versus 0.35 kWh/kg for Li-S). Even allowing for the relatively poor efficiency of internal combustion engines, onboard electric power generation remains a highly effective way of reducing the battery mass.
Existing solutions typically use a brushless DC electric motor configured as a 3-phase alternator as shown on the right. All Millswood Engineering products use this arrangement.
Millswood Engineering makes several UAV generation products:
A complete off-the-shelf solution for small to medium-sized UAVs. Includes 3-phase rectification, dual battery chargers, DC-DC conversion to multiple output rails, user-configurable output voltages, CAN and RS232 interfaces, and supports up to 6S battery voltages. The 250W PMU has been in production since 2014, and has been installed in many different types of UAV - both fixed and rotary wing.
250W Power Management Unit - Version 2
As above, but with increased output power, increased input voltage range, a master shutdown input, improved configuration software, and a range of other enhancements.
2000W Generator Control Unit (GCU)
Includes 3-phase rectification, dual battery support, DC-DC conversion to dual regulated output rails, CAN and RS232 interfaces, and supports up to 14S battery voltages. An engine starter is available as an option. This product is available exclusively from VISIONAIRtronics.
900W Power Distribution Unit (PDU)
Designed to complement the 2000W GCU, this product takes the dual high-voltage rails created by the GCU and down-converts them to be suitable for Avionic, Servo and Payload devices. Includes CAN and RS232 interfaces and internal redundancy. This product is available exclusively from VISIONAIRtronics.
1800W Power Distribution Unit (PDU)
As above, but with twice the power. Also available exclusively from VISIONAIRtronics.