Research On Key Technologies Of Wireless Laser Power Transfer System

Laser power transmission(LPT)is one of the most promising technology in the long-rang wireless power transfer field.LPT research has been driven by the desire to remotely power unmanned aerial vehicles(UAVs),satellites and other mobile electric facilities.However,the low overall efficiency is the main issue that limits the implement of high intensity laser power beam(HILPB)system.LD is a core component in the system.Its conversion efficiency depends on the input current source.Normally,the LD can operate in either continuous mode(CM)or pulse mode(PM)according to different input currents.The injected current has a direct effect on the electro-optical conversion efficiency of LD.Therefore,improving the efficiency of LD depends not only on the progress of its structure,material and manufacturing technology,but also on the injection of high quality current.In order to further improve the performance of LD,the optimal injected current is investigated in this paper.To that end,the impact of injected current on the electro-optical conversion efficiency of the LD is presented and discussed.Based on the simulation analysis,driving LD in the pulse mode gives a better performance.The main ideal of this efficiency optimization method is that the operation point of LD would be changed by changing the input of current of LD,and the change of the operation point of LD directly affects the efficiency of the LD.In addition,LD current source driver is also a major component in the HILPB system,whose performance directly affects the conversion efficiency and the lifetime of LD.To verify the simulation results,a switching mode current regulator that can operates in both continuous mode and pulse mode is fabricated and tested in the lab.The switching mode current regulator is composed by a buck converter and a buck/boost converter.The buck converter employs average current control,with the objective of providing the average output current to the LD during the operation.The buck/boost converter generates the ac component of the output current when the regulator operating in pulse mode.Moreover,energy storage capacitor of the buck/boost converter can be reduced by controlling the voltage of it,so that the power density of the power supply can be improved.Both the buck converter and the buck/boost converter need to be properly designed according to their different functions.Experimental results show a good matching with the simulation analysis.In conclusion,the proposed LD efficient current driving technology provides a theoretical basis for the operation of the LD and design of LD driving power supply.In the HILPB system,the conversion efficiency at the photovoltaic(PV)receiver will limit the performance of an implemented system.One of the major factors that contribute to the reduction of PV power is Gaussian laser beam.Different PV configurations can be used to reduce the losses caused by Gaussian laser beam.In this paper,an optimal PV array configuration search mechanism for arbitrarily sized PV arrays to enhance the PV power under Gaussian laser beam condition is proposed.In order to do so,the irradiance profile of the Gaussian laser beam is mathematically modeled,which plays an important role in modeling the PV arrays and designing the optimal configuration research algorithms.The corresponding optimal configuration research algorithms for different PV array architectures are proposed so as to maximize the PV array output power under Gaussian laser beam condition.All the possible optimal solutions for different architectures are compared with each other to find out which one maximizes output power by means of simulations and experiments.The performance of the all available configurations for SP and TCT architecture are investigated under Gaussian beam condition and both simulation and experimental results show that the power extracted under Gaussian beam condition is greater with the TCT configuration compared with other configurations.The experimental and simulation results are shown to verify the proposed search mechanism.Above all,the proposed optimal configuration research algorithm can provide a specific solution for the PV array in the LPT system,which has important practical application valueThe laser based wireless power transmission(LWPT)system is one of the most promising system in the long-rang wireless power transfer field.However,the low overall efficiency is the main issue that limits the implement of LWPB system.At present,since most of the LWPT systems are open-loop systems,it is difficult to make the best use of lasers and PV cells in the system,thus the operation system efficiency can’t be further improved.In this paper,a power management control strategy is proposed in order to ensure that the system operates with high efficiency.The main idea of the power management control strategy is that the instantaneous transmission power in the system can be changed by optimizing the duty ratio of the input current of the laser,while the laser and PV array have high efficiency in the case of higher transmission power.Therefore,the laser and PV array can be fully used.In order to do so,the efficiency characteristics of laser and PV array under different operation mode are analyzed by means of theoretical analyses and experimental measurements.It is indicated that the duty cycle of laser input current has a direct effect on the system efficiency.On the basis of this system characteristic,a search algorithm,which borrows the concept of P&O algorithm,is proposed as the system power management control strategy,in order to obtain the desired duty cycle,thus to improve the system efficiency.Finally,a prototype is fabricated and tested in the lab,and the experiment results show that the proposed control scheme can effectively improve the system efficiency.In summary,It is of great guiding significance for the proposed power management control strategy,which provides an effective mechanism for transmitter/receiver mutually efficient cooperation.