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The Energy Systems Team develops lightweight power electronics technologies for converting wind energy at the wing into electrical energy on the ground.
Using high power density brushless DC motors, mechanical energy at the rotor blades is converted into electrical energy at the wing. Motor drive electronics regulate this process to ensure reliable generation and control of wing flight speed. The tether moors the wing to the ground and carries the electricity generated to the ground station where the energy generation system interfaces with the larger electrical grid.
To meet the unique demands of the Airborne Wind Turbine (AWT), Makani has developed technologies in power generation electronics, tethers and ground systems.
Small, high speed motors form the heart of the lightweight power generation system for the 10 kW wing. High apparent wind speeds at the wing and recent advances in brushless DC motor technology allow for a significant reduction in weight and size compared with conventional wind turbines.
Makani has developed a high voltage, 4-quadrant motor controller that assembles in a tight mechanical package designed to fit inside the wing. Switching frequency was optimized to maximize speed loop responsiveness while maintaining high system efficiency and minimal torque ripple. Additionally Makani has developed a high-voltage buck converter that allows the on-wing electronics to run off of the power generated by the turbines.
The Makani motor and motor drive electronics are bench-tested against expected flight conditions to validate performance and ensure reliable operation in flight.
Makani has designed and constructed application specific tethers that are lightweight and robust, to withstand the dynamic conditions observed during flight. Generating power at high voltage reduces the tether weight and cross-section, providing a significant cost reduction and boost in energy generation. Here the electrical conductors are wound onto the tether structural member.