Power control method for improving efficiency of laser-based wireless power transmission system

Abstract

Laser-based wireless power transmission (LWPT) systems are one of the most promising systems in the long-range wireless power transfer field. However, few studies have focused on the efficiency characteristics of LWPT systems. Therefore, most LWPT systems are open-loop systems, making it difficult to best utilise their lasers and photovoltaic cells, thus preventing the system efficiency from being further improved. In this study, a closed-loop power control method is proposed for LWPT systems to explore the best performance conditions for such systems. To this end, the efficiency characteristics of a system are investigated by means of theoretical analysis and experimental measurements. The results show that the duty cycle of the laser input current is one of the key factors for improving the system efficiency. Then, a dual closed-loop controller, which includes an optimal duty cycle search algorithm, is proposed based on the obtained system characteristics. Finally, a small-scale prototype is fabricated and tested in the laboratory to verify the effectiveness of the proposed power control method.