Analysis and Experiment of Laser Energy Distribution of Laser Wireless Power Transmission Based on a Powersphere Receiver

Abstract

Laser wireless power transmission (WPT) is one of the most important technologies in the field of long-range power transfer. This technique uses a laser as a transmission medium instead of conventional physical or electrical connections to perform WPT. It has the characteristics of long transmission distance and flexible operation. The existing laser wireless power transmission system uses photovoltaic cells as a receiver, which convert light into electricity. Due to the contradiction between the Gaussian distribution of laser and the uniform illumination requirements of photovoltaic cells, the laser wireless power transmission technology has problems such as low transmission efficiency and small output power. Therefore, understanding the energy distribution changes in the laser during transmission, especially the energy change after the laser is transmitted to each key device, and analyzing the influencing factors of the energy distribution state, are of great significance in improving the transmission efficiency and reducing the energy loss in the system. This article utilizes the optical software Lighttools as a tool to establish a laser wireless power transmission model based on a powersphere. This model is used to study the energy distribution changes in the laser as it passes through various components, and to analyze the corresponding influencing factors. To further validate the simulation results, an experimental platform was constructed using a semiconductor laser, beam expander, Fresnel lens, and powersphere as components. A beam quality analyzer was used to measure and analyze the laser energy distribution of each component except for the powersphere. The output voltage and current values of various regions of the powersphere were measured using a multimeter. The energy distribution of the powersphere was reflected based on the linear relationship between photo-generated current, voltage, and light intensity. The experimental results obtained were in good agreement with the simulation results. Simulations and experiments have shown that using a beam expander can reduce divergence angle and energy loss, while employing large-aperture focusing lens can enhance energy collection and output power, providing a basis for improving the efficiency of laser wireless power transfer.

Experimentation and Analysis of Intra-Cavity Beam-Splitting Method to Enhance the Uniformity of Light in the Powersphere

“…And the red objects in the figure are the semi-transparent and semi-reflective lenses. Figure 5b [32] is the ray-tracing diagram without adding three beam splitters at the center of the sphere. Comparing the two figures, it can be clearly seen that after adding a semi-transparent and semi-reflective lens, the ray density on the inner surface of the powersphere is significantly improved.…”

“…Finally, there are the upper and lower parts of the powersphere, and they are the regions illuminated by multiple reflected lights. Figure 6a is the light intensity distribution diagram with three semi-transparen semi-reflective lenses added at the center of the sphere, and Figure 6b [32] is the intensity distribution diagram without a beam splitter at the center of the sphere. coordinate in the figure is the Z-axis of the incident light, where 0° on the V-axis sponds to the center of the light spot irradiating the powersphere.…”

“…In order not to affect the overall effect, these cells were removed before the experiment. They were disconnected from the total circuit so that no voltage and current were generated [32].…”

“…In order not to affect the overall effect, these cells were removed before the experiment. They were disconnected from the total circuit so that no voltage and current were generated [32]. In order to gain a more detailed understanding of the beam splitting effects, the voltage and current distribution curves with beam splitting, as shown in Figure 8, were combined with the voltage and current distribution curves without beam splitting to create a consolidated graph presented as Figure 9.…”

“…This solution aimed to take advantage of the inherent light uniformity and high-power input capability of a large-sized sphere, thus increasing the input power to 3000 W [31]. However, due to the high absorption rate of the photovoltaic cells, the direct irradiation area on the inner surface of the powersphere exhibits a significantly higher light intensity than the reflected area, resulting in a suboptimal level of light uniformity [32].…”