Lifetime Estimation and Dimensioning of the Machine-Side Converter for Pumping-Cycle Airborne Wind Energy System

Fostering of high altitude wind energy (HAWE) resources above 200 meters is a recent promising technology that seeks to capture the strong wind currents at high elevations. Among the many concepts of airborne wind energy (AWE) generators, the soft-kite pumping-cycle (PC) concept promises to provide a very lightweight, high power density, and cost-effective solution. In this study, the impact of the load-cycle on the lifetime of the machine-side converter (MSC) is examined. By employing a physics-of-failure estimation approach, the main pumping-cycles and the machine speed-reversal were identified as the primary adverse influencers of the IGBT and diode solder joints. Whereas, wind speeds around 12 m/s contribute the most to the predicted degradation. To fulfill the thermal limitations and the lifetime requirements of the application, an optimum converter dimension is found using linear scaling of the semiconductors chip-area and the heatsink thermal impedances. With the generation (reel-out) phase power defined as the base value, the results suggest that the converter needs to be scaled by at least 150 % to meet the thermal constraints, and by 350 % to approach the target lifetime of ten years.