Distributed Laser Charging: A Wireless Power Transfer Approach

TL;DR

This paper introduces a detailed analytical model for distributed laser charging (DLC), a wireless power transfer method, evaluating its efficiency and system design considerations for powering IoT devices over meter distances.

Contribution

It presents a comprehensive multi-module DLC system model, deriving maximum power transmission efficiency and analyzing the effects of various parameters, advancing the theoretical understanding and practical design of DLC.

Findings

Maximum power transmission efficiency derived in closed-form.

Efficiency varies with laser wavelength, distance, and PV-cell temperature.

Model validated through measurements and simulations.

Abstract

Wireless power transfer (WPT) is a promising solution to provide convenient and perpetual energy supplies to electronics. Traditional WPT technologies face the challenge of providing Watt-level power over meter-level distance for Internet of Things (IoT) and mobile devices, such as sensors, controllers, smart-phones, laptops, etc.. Distributed laser charging (DLC), a new WPT alternative, has the potential to solve these problems and enable WPT with the similar experience as WiFi communications. In this paper, we present a multi-module DLC system model, in order to illustrate its physical fundamentals and mathematical formula. This analytical modeling enables the evaluation of power conversion or transmission for each individual module, considering the impacts of laser wavelength, transmission attenuation and photovoltaic-cell (PV-cell) temperature. Based on the linear approximation of electricity-to-laser and laser-to-electricity power conversion validated by measurement and simulation, we derive the maximum power transmission efficiency in closed-form. Thus, we demonstrate the variation of the maximum power transmission efficiency depending on the supply power at the transmitter, laser wavelength, transmission distance, and PV-cell temperature. Similar to the maximization of information transmission capacity in wireless information transfer (WIT), the maximization of the power transmission efficiency is equally important in WPT. Therefore, this work not only provides the insight of DLC in theory, but also offers the guideline of DLC system design in practice.