Presentations

Abstract

Airborne wind energy systems (AWES) impose drivetrain requirements that differ fundamentally from conventional wind turbines. Ground-based “yoyo” systems operate in pumping cycles with alternating reel-out (power generation) and reel-in (power consumption) phases. To minimize cost and complexity, demonstrators increasingly adopt single-machine drivetrains rather than separate motor and generator units. The electrical machine must therefore deliver four-quadrant operation, repeatedly crossing zero speed under load during reversals, while tracking rapidly varying torque–speed commands over a wide envelope. Compared with conventional wind energy systems, the cycle is markedly more dynamic, mechanical inertia is lower, and efficient operation is required at multiple operating points rather than near a single rated point. A dual-use ground station has been developed at technology readiness level 4 (TRL 4) and is capable of both field operation and laboratory power-hardware-in-the-loop (PHIL) testing. In PHIL mode, two coupled three-phase machines exchange real power through back-to-back converters: one machine operates as the AWES generator, while the other reproduces tether forces and flight dynamics under the control of a real-time emulator. This configuration enables full pumping cycles to be simulated and allows systematic evaluation of machine types and control strategies before deployment. The contribution motivates and assesses the synchronous reluctance machine (SynRM) as an alternative to induction machines (IM) and permanent-magnet synchronous generators for single-machine AWES. SynRM combines rare-earth-free construction, low rotor inertia, high efficiency, and mechanical simplicity-attributes aligned with frequent reversals, zero-speed torque, and fast transients. A comparative PHIL campaign on a 15-kW platform is outlined, with performance criteria relevant to AWES: bidirectional efficiency over the cycle, dynamic torque tracking at reversals, thermal loading, DC-bus behavior, and control implications. The work provides an application-driven rationale for machine selection in emerging AWES.