| In systems using laser as the energy carrier for long-range power transmission,the quality of the laser beam at the transmitting end,and the combination of the receiving photoelectric conversion devices can have a significant impact on the overall efficiency of the power transmission system.In this paper,the characteristics of the laser beam(808nm wavelength)output by the optical fiber are analyzed.Combined with the transmission theory of the light beam in the optical fiber,the numerical simulation of the change of the optical beam parameter in the optical fiber is carried out.The feasibility of improving the uniformity of the laser beam at the emitting end in a laser energy transmission system by changing the transmission distance of the light beam in the optical fiber is explored and verified by experiments.On this basis,the relationship between open-circuit voltage,short-circuit current,fill factor,photoelectric conversion efficiency and irradiation laser power density of monolithic single-cell battery when using an efficient single-junction GaAs cell at the receiving end is studied.Meanwhile,the output characteristics of the battery components in the case of different connections with when the laser power density,laser beam uniformity change are studied.Firstly,the basic composition of the laser wireless power transmission system and the working principle and output characteristics of the laser light source----808 nm semiconductor laser used in this project are introduced.The characteristics of the laser beam output by the optical fiber are analyzed.Combined with the transmission theory of the light beam in the optical fiber,a new method to optimize the homogeneity of the laser beam is proposed,which is the method to increase the uniformity of the semiconductor laser beam by lengthening the fiber length.The method is validated experimentally.Then the laser output from the fiber is reused by the inverted telescope system,so a uniform laser beam with good uniformity and directivity is obtained.Secondly,the working principle and the volt-ampere characteristics of single-junction gallium arsenide cells used in this project are introduced.Based on this,the working principle and volt-ampere characteristics of the photovoltaic modules formed by two photovoltaic cells connected in series and in parallel are analyzed and calculated.Finally,the relationship between open-circuit voltage,short-circuit current,fill factor,photoelectric conversion efficiency and laser power density of single-chip battery is studied through experimental measurement and theoretical analysis.And in the case of different connection modes,Output characteristics with the laser power density,laser beam uniformity change are studied.The research results show that the homogeneity of the laser beam before the homogenization is poor and the spot uniformity after homogenization is greatly improved.For the photovoltaic module composed of two photovoltaic cells connected in series or in parallel,when photo-cell light intensity is basically same,the laser conversion efficiency of the two connection modes of the photovoltaic cell components is basically the same,but the use of series mode can increase the output voltage of photovoltaic modules.In the case of a large difference in the light intensity of the two photocells,although the output voltage of the parallel components is lower,the circuit efficiency and stability are higher than that of the series components.the output voltage of parallel components is lower,but the circuit efficiency and stability are higher than the series components.The research results have reference value for improving the efficiency of laser infinite energy transmission system. |
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