Photovoltaic cell is one of the most important components of laser powered unmanned aerial vehicle. Illuminated by high power laser beam, photovoltaic cell temperature increases significantly, which leads to efficiency drop, or even physical damage. To avoid such situation, the temperature of photovoltaic cell must be predicted precisely. A dynamic thermal model of photovoltaic cell is established in this paper, and the relationships between photovoltaic cell temperature and laser power, wind speed, ambient temperature are also analyzed. Simulation result indicates that illuminated by a laser beam, the temperature of photovoltaic cell rises gradually and reach to a constant maximum value. There is an approximately linear rise in photovoltaic cell temperature as the laser flux gets higher. The higher wind speed is, the stronger forced convection is, and then the lower photovoltaic cell temperature is. But the relationship between photovoltaic cell temperature and wind speed is not linear. Photovoltaic cell temperature is proportional to the ambient temperature. For each increase of 1 degree of ambient temperature, there is approximate 1 degree increase in photovoltaic cell temperature. The result will provide fundamentals to take reasonable measures to control photovoltaic cell temperature.
Micro unmanned aerial vehicle, mostly powered by electricity, plays an important role in many military and civil
applications, e.g. military detection, communication relay et al. But restricted endurance ability severely limits its
applications. To solve the problem, laser wireless power transmission system is proposed. However, overall efficiency of
the system is quite low. This paper describes basic structure of laser wireless power transmission system and its working
process. The system consists of two major modules: a high power laser source transmitting energy and a photovoltaic
receiver converting optical energy into electricity. Then factors influencing efficiency of the system are analyzed. It
suggests that electro-optical efficiency of laser, atmospheric impact on laser beam and photo-electric efficiency of
photovoltaic receiver play significant role in overall efficiency of the system. Atmospheric impact on laser beam mostly
derived from refraction, absorption, scattering and turbulence effects, leads to drop in energy and quality of laser beam.
Efficiency of photovoltaic receiver is affected by photovoltaic materials. In addition, matching degree between intensity
distribution of laser beam and layout of photovoltaic receiver also obviously influence efficiency of photovoltaic receiver.
Experiment results suggest that under non-uniform laser beam illumination, efficiency of photovoltaic receiver mostly
depends on layout of photovoltaic receiver. Through optimizing the layout of photovoltaic receiver based on intensity
distribution of laser beam, output power is significantly improved. The analysis may help to take corresponding measures
to alleviate negative effects of these factors and improve performance of laser wireless power transmission system.