INCREASING THE AUTONOMY OF AN UNMANNED AERIAL VEHICLE WITH A LOW TAKE-OFF MASS

Uporaba brezpilotnih letalnikov postaja del našega vsakdana. Ti se uporabljajo tako za civilne kot tudi vojaške namene. Vedno več pa je namenov uporabe, ki zahtevajo večjo avtonomijo letalnika. V disertaciji so tako raziskane možnosti, ki omogočajo povečanje avtonomije letalnika, pri čemer sta bili najbolj primerni možnosti – uporaba baterije z večjo gravimetrično energijsko gostoto, ter uporaba sončnih modulov, tudi preskušeni. Za namen povečanja avtonomije so bili implementirani sončni moduli na osnovi spojine galijevega arzenida (GaAs), izdelali pa smo tudi namenski MPPT (angl. Maximum Power Point Tracking) regulator z integriranim P&O (Perturb & Observe) algoritmom za namen doseganja čim večjega izkoristka sistema za proizvodnjo električne energije iz sončne energije. V disertaciji je predstavljena tudi matematična izpeljava enačbe za izračun proizvedene električne energije na osnovi rotacij letalnika v prostoru, znane lokacije in časa poleta, znane pozicije Sonca na nebu v času poleta, ter posredno znane direktne in difuzne jakosti sončnega sevanja na horizontalno podlago. S testnimi poleti smo izvedli tudi primerjavo med izračunano in dejansko proizvedeno električno energijo. Dosegli smo energijsko učinkovitost regulatorja MPPT višjo od 96,3 % ter povečanje avtonomije letalnika do 21,3 %.The use of unmanned aerial vehicles (UAVs) is becoming part of our daily lives. They are used for both civilian and military purposes. However, there are more and more applications that call for higher autonomy of the aircraft. In the dissertation, options to increase the autonomy of the aircraft were explored. The most suitable options – usage of battery with a higher gravimetric energy density and the use of solar modules were also tested. In order to increase the autonomy, solar modules based on gallium arsenide (GaAs) were implemented and a dedicated MPPT (Maximum Power Point Tracking) controller with an integrated P&O (Perturb & Observe) algorithm was developed in order to achieve the highest possible efficiency of the system that produce electricity from the solar energy. The dissertation also presents a mathematical derivation of the equation needed to calculate the produced electrical energy based on the aircraft rotations, known time and location of the flight, known positions of the Sun in the sky during the flight, and indirectly known global and diffuse solar irradiation on the horizontal plane. A comparison between calculated and actually produced electricity on the basis of five actually performed test flights, is also included. Experimental results demonstrated the energy efficiency of the MPPT controller higher than 96.3 % and the increase in aircraft autonomy of up to 21.3 %