Aerospace

PMW developed a brushless DC electric motor and drive (motor controller) for an all electric aircraft intended to say aloft for as long as a year at a time. It was the product of a challenge laid down by the aircraft’s designers Prismatic Ltd for its PHASA-35 high altitude, long endurance unmanned aerial vehicle (HALE UAV)

With twin bespoke electric motors directly driving high altitude propellers, the craft has arrays of solar panels to provide the power by day and recharge its batteries for flying at night

The cutting edge motor, drive and commutation system was required not to overheat at take off or during the fast climb necessary to reach its 65,000 feet cruising altitude in the limited time allowed

To do this, PMW’s design team quickly gained a precise understanding of the thermal performance required for the motor at all altitudes. The near space environment meant taking into consideration ambient temperatures of -80°C and a very low air pressure of 5.6 kPa

This required a detailed understanding of the three-dimensional heat dissipation from the motor and adjacent components, while ensuring every motor, drive and commutation component was both mechanically and electrically rated for all these conditions.

The phase-gated project included electromagnetic modelling, mechanical design, finite element analysis, component sourcing and procurement, and selection of specialist subcontractors to work with the extreme materials and precision required, followed by manufacture, assembly and test at both ambient and low temperatures