Multi-Field Coupling Characteristics of Laser Wireless Power Transmission Receiving End Under Atmospheric Influence
Objective The primary obstacle currently impeding the widespread adoption of laser wireless power transmission(LWPT)lies in the challenge associated with long-distance power transport and efficient conversion.As laser beams propagate through the atmosphere,they produce a series of linear and nonlinear effects.The energy carried by the laser is absorbed or scatted by atmospheric gas molecules and aerosol particles.Atmospheric turbulence induces light intensity fluctuation,beam jitter,beam spreading,and variation of arrival angle.The light field at the receiving end is directly influenced.The receiving end is generally composed of multiple photovoltaic cells in series and parallel,and its output characteristics are directly affected by the light field.At the same time,a portion of the laser energy is converted into electrical energy,while the rest is converted into heat energy,influencing the temperature distribution at the receiving end.The light field,electric field,and heat transfer characteristics of the LWPT receiving end interact and constrain each other.Therefore,studying the multi-field coupling characteristics of photovoltaic cells at the receiving end is meaningful.Our study provides a reference for the design and optimization of LWPT systems.Methods We utilize an LWPT experimental platform to obtain the output characteristics of photovoltaic cells.The data is processed through multiple nonlinear regression to obtain the undetermined coefficientsC1,C2,and C3,series resistance Rs,and ideality factor n in the I-V equation.The fitting results closely align with the experimental data.Beer's law is used to compute the transmission efficiency of three different laser wavelengths through the atmosphere.The power spectrum inversion method is used to simulate the light field distribution in front of the receiving end under different turbulence structure constants,and the light field distribution is used as the source to solve the partial differential equation using finite element analysis software to obtain the multi-field coupling characteristics of photovoltaic cells.Results and Discussions We establish an LWPT experimental platform to measure the output characteristics of photovoltaic cells within a specific irradiance range.Multivariate parameter regression is performed using I-V data to obtain equation coefficients,series resistance,and ideality factors.The fitting results closely align with the experimental data,with a fitting variance of 0.996(Fig.8).The transmission efficiency of three commonly used laser wavelengths,namely 532 nm,808 nm,and 1060 nm in the atmosphere,is calculated.It is observed that the transmission efficiency exponentially decays with the increase in transmission distance.Furthermore,under equivalent transmission distances,shorter laser wavelengths exhibit greater attenuation degrees(Fig.9).The power spectrum inversion method is used to simulate the light field distribution in front of the receiving end under different turbulence structure constants,and the light field distribution is used as a source term to calculate the multi-field coupling characteristics at the receiving end.Atmospheric turbulence causes distortions of light spots at the receiving end,with stronger turbulence resulting in more disorderly light spots,and even fragmentation is observed(Fig.13).The potential,current density,and temperature at the receiving end are positively correlated with the surface irradiation intensity,but the surface potential distribution trend is not affected,showing an overall trend of weak on both sides and strong at the center(Fig.14).The I-V and P-V characteristic curves,open circuit voltage,short-circuit current,and photoelectric conversion efficiency of photovoltaic cells under three different turbulence intensities are calculated.The strength of turbulence directly affects the output characteristics of photovoltaic cells.As turbulence intensifies,the maximum power is 0.075 W,0.031 W,and 0.021 W,respectively.The photoelectric conversion efficiency decreases slightly but overall remains around 15％,specifically 15.85％,14.82％,and 14.34％,respectively(Table 7).Conclusions We investigate the impact of the atmospheric environment on the multi-field coupling characteristics of photovoltaic cells in actual conditions by establishing an LWPT experimental platform,constructing both an atmospheric turbulence transmission model and a multi-physical field model at the LWPT receiving end.The results show that during the atmospheric transmission of laser,the efficiency of atmospheric transmission of laser beams experiences exponential decay with increasing transmission distance,eventually converging to zero.Key determinants of atmospheric attenuation include laser wavelength,altitude,climate type,visibility,and other pertinent factors.At the same time,atmospheric turbulence can cause phase distortion of the laser beam,leading to uneven,disordered,and even fragmented light fields at the receiving end.The irradiation intensity is closely related to the surface current density and temperature distribution of photovoltaic cells,which in turn changes the output characteristics of photovoltaic cells.When the turbulence intensity increases,the photovoltaic conversion efficiency,and the photovoltaic cells output performance are impaired.
atmospheric opticslaser wireless power transmissionatmospheric turbulencemulti-field couplingI-V characteristics
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