半导体激光无线传能中光伏电池转换效率

为选择合适的激光参量与光伏电池参量，以提高激光无线能量传输(LWPT)系统的能量转换效率，通过实验研究了LWPT系统中能量接收单元，也即光伏电池在半导体激光照射下的输出特性。通过波长为808 nm和915 nm的激光辐照GaAs和Si光伏电池，研究了不同激光功率密度、光伏电池温度、电池类型以及激光入射角度对光伏电池输出特性与能量转换效率的影响。实验中，在波长为808 nm的激光功率密度从0.06 W/cm2上升至0.37 W/cm2的过程中，Si电池的最大输出功率从0.12 W上升至0.32 W，能量转换效率从50.9%下降至21.2%；GaAs电池的最大输出功率从0.40 W上升到1.07 W，能量转换效率从57.9%下降至23.8%。随着激光功率密度的增加，光伏电池的输出功率先增加而后趋于饱和，但是高功率密度激光引起的电池温升会导致其光电转换效率的下降，所以激光功率密度的选择与光伏电池温度的控制是提高LWPT系统能量转换效率的关键因素。

Power conversion efficiency of photovoltaic cells in semiconductor laser wireless power transmission

In order to choose the best laser parameters and the photovoltaic cells (PV cells) parameters to reach a high power conversion efficiency (PCE) of the laser wireless power transmission (LWPT) system, we experimentally studied the output characteristics of the receiving system, the PV cells, under laser irradiation. The GaAs and Si PV cells were irradiated by laser with wavelengths of 808 nm and 915 nm, and the output characteristics and PCE of the PV cells under different conditions were analyzed. These conditions include: laser power intensity, laser incidence angle, temperature and material of the PV cells. In the experiment, when 808 nm laser power intensity increased from 0.06 W/cm2 to 0.37 W/cm2, the maximum output power of Si PV cell increased from 0.12 W to 0.32 W, but its PCE decreased from 50.9% to 21.2%; the maximum output power of GaAs PV cell increased from 0.40 W to 1.07 W, but its PCE decreased from 57.9% to 23.8%. The experimental results show that with the increase of laser power density, the output power of PV cells increases at first and then tends to be stable, but the temperature rise caused by high power intensity laser will lead to the decrease of power conversion efficiency of PV cells. So, the selection of laser power intensity and the temperature control of PV cells are keys to increase the PCE of LWPT system.