Catalogue Search | MBRL
Are you sure you want to remove the book from the shelf?
{{itemTitle}}
6,176
result(s) for
"Wireless power transmission"
Sort by:
Efficient LED-Array Optical Wireless Power Transmission System for Portable Power Supply and Its Compact Modularization
Optical wireless power transmission (OWPT) has been a promising solution for remote power supply, eliminating the need for power cables or batteries. In this paper, we propose a light emitting diode (LED) array based OWPT system with improved transmission efficiency and compact system dimension. In this experiment, the proposed four-LED-array collimation scheme achieved a lens system efficiency as high as 70%, while obtaining an electrical power of 0.8 W from a 50 × 50 mm2 GaAs solar cell at 1 m. The emitting side with the lens system was integrated into a 120 × 114 × 61 mm3 portable device by 3D printing. In addition, the thermal performance of the integrated module and the effective surface irradiance at the receiving side were analyzed in detail. The proposed system exhibits high efficiency and portability, with the advantageous potential to temporarily power remote devices.
Journal Article
Camera-Based Safety System for Optical Wireless Power Transmission Using Dynamic Safety-Distance
This paper introduces a new safety approach for Optical Wireless Power Transmission (OWPT), a technology that is integral to the new kinds of Wireless Power Transmission technology (WPT). It starts from the fundamental configuration of the current OWPT system, addressing the safety concerns related to lasers by involving laser irradiation hazards, laser exposure regulation and guidelines, and a comparison with other safety methods. A camera-based OWPT safety system focused on the emission control of the light source is proposed, and it utilizes a depth camera and finely tuned computer vision-based control program. Through meticulous system design and experiments, the proposed system can detect moving objects in a limited indoor environment and control the laser/LED light transmission according to the object’s velocity dynamically. Various functions and exclusive improvements towards OWPT operation are mentioned, and Dynamic Safety-Distance is proposed as the core mechanism of the safety system. Through on-site experiments, indoor safety control and system operation’s evaluation are discussed, acknowledging both the advantages and limitations of the proposed safety system. This paper concludes with suggestions for further developments in camera-based OWPT safety incorporating the concept of Automatic Emission Control.
Journal Article
Optimization for Compact and High Output LED-Based Optical Wireless Power Transmission System
Optical wireless power transmission (OWPT) is a technology that supplies energy remotely. Due to the great advantages of long transmission distances, high directionality, no electromagnetic interference noise, and loose safety regulations, light emitting diode (LED) based OWPT systems become appropriate candidates for powering various applications, especially for the Internet of things (IoT). In this paper, improved LED-OWPT systems are proposed based on a collimation scheme for optimizing the system dimension and output. In a single LED configuration, the system dimension is compressed by 46% while the high transmission efficiency is maintained. As for the LED-array system, the dimension is compressed by 56%, and the output is enhanced by 40%. In the experiment, a high electricity output of 532 mW is achieved at 1 m transmission distance. In addition, the effect of misalignment between LED and lens and the potential of long-distance transmission are clarified in the LED-array OWPT system.
Journal Article
Design and Efficiency Optimization of Distributed Laser Wireless Power Transmission Systems Through Centralized Scheduling and Current Regulation
This paper presents an efficiency optimization method for laser wireless power transmission (LWPT) system, focusing on the coordination and control of multiple laser diodes. A distributed laser wireless power transmission (D-LWPT) system is proposed, which includes multiple independent and parallel power transmission chains. The system has the characteristics of power scalability, redundancy, and control flexibility. The efficiency characteristics of each key component in the LWPT system are discussed. Due to the internal losses of the laser, the transmission efficiency is also affected by the transmission power. For distributed architecture, its flexibility allows for the rational allocation of transmission power. To achieve optimal efficiency, a central scheduling controller is designed to regulate the current of LDs. A swarm intelligence-based optimization algorithm is used to determine the optimal operating current. This significantly improves the system’s efficiency and ensures real-time control. Experimental results validate the effectiveness of the proposed techniques. The DC to DC efficiency of the power transmission chain can reach over 14%, and the photovoltaic array can output a maximum power of over 130 W. The impact of beam combination on the efficiency and output power of PV arrays is less than 3%, indicating that the distributed structure does not affect system performance. The experimental results show that the proposed efficiency optimization method has excellent power following performance (algorithm execution time < 10 ms) and effective efficiency optimization performance. Under light load conditions, the LDs’ efficiency is optimized from 27.5% to 45.0%, and under medium load conditions, it is optimized from 41.5% to 44.5%. This distributed structure and efficiency optimization method provide a solution for improving the performance of LWPT systems.
Journal Article
System Level Requirement Analysis of Beam Alignment and Shaping for Optical Wireless Power Transmission System by Semi–Empirical Simulation
Since optical wireless power transmission (OWPT) transmits power by light, which has a narrow diffraction angle feature, it is a strong candidate for wireless power transmission systems supporting long ranges. To develop a realistic operational OWPT system, clarification of system level requirements is essential. In this study, to fill a gap between the concept/initial demonstration and an operational system, the required conditions were analyzed regarding the effects of beam alignment and shaping on the power generation ratio which is a system level efficiency factor with extension from the formerly reported one-dimensional analysis to three-dimensional to include errors in all degrees of freedom is presented. This extension is regarded as an indispensable methodology to evaluate the system level performance of general OWPT systems. Numerical requirements for beam alignment and shaping are derived for both non-cooperative and cooperative OWPT. In non-cooperative OWPT, the direction of the solar cell module is fixed, and the transmitter aligns its beam with the module. In cooperative OWPT, the module and transmitter mutually align in the same direction. Though the cooperative OWPT is more restrictive than the non-cooperative one, its advantages were clarified.
Journal Article
1 W High Performance LED-Array Based Optical Wireless Power Transmission System for IoT Terminals
Optical wireless power transmission (OWPT) is a promising technology for remote energy supply, especially for powering Internet of things (IoT) terminals. Light-emitting diode (LED)-based power sources of OWPT are attractive for the development of high-performance systems without the constraints of safety issues. In this paper, the electricity output of a near-infrared LED-OWPT is significantly improved. The saturation output caused by the small lens aperture in the LED array collimation scheme was analyzed. The experiment achieved a maximum electricity output of more than 1 W from a 50 × 50 mm2 GaAs solar cell at 1 m transmission distance. In addition, the thermal features also proved the feasibility of a high-output LED-OWPT system for practical applications.
Journal Article
Enhancing Alignment Accuracy in Laser Wireless Power Transmission Systems Using Integrated Target Detection and Perturbation-Observation Method
This paper introduces a high-precision alignment method for laser wireless power transmission (LWPT) systems, integrating neural network-based target detection with a perturbation-observation technique. The objective is to enhance the alignment accuracy between the laser spot and the photovoltaic array, thereby improving energy transfer efficiency. The method’s key feature is its ability to achieve these results without requiring additional optical components, simplifying system design. Continual assessment and adjustment based on real-time output power data ensure optimal alignment, maximizing the photovoltaic array power output. Experimental results demonstrated that the proposed method achieved an initial alignment precision with pixel errors below 3%, translating to a physical error of approximately 7 mm. Fine-tuning through the perturbation-observation method further optimized the alignment, resulting in a photovoltaic array power output of 98.70% of its maximum potential. This hybrid approach provides a reliable solution for boosting the performance of LWPT systems, offering significant potential for practical applications.
Journal Article
Solar Cell Detection and Position, Attitude Determination by Differential Absorption Imaging in Optical Wireless Power Transmission
In optical wireless power transmission, position, size, and attitude of photovoltaic device (PV) must be determined from light source. A method proposed in the previous report is based on selective absorption characteristics of PV, and it is detected by differentiating images of strongly absorbable wavelength and one not. In this study, using two infrared wavelengths, two kinds of targets were detected by differential absorption imaging. One was a GaAs substrate which simulates diffuse rear surface, and the other was a real GaAs PV. It was found that the substrate’s reflective characteristic was diffuse, and the solar cell’s was mainly non-diffuse and accompanied by small diffuse component supporting wide-angle reflection. Using this feature, the position of the GaAs solar cell could be determined within a wide range of angle. Its attitude could also be determined with an accuracy of ±10 degrees to its normal. The position of diffuse GaAs substrate could be determined within a wide range of angles, and its attitude determination was proposed by exploiting its varying apparent size with tilt angle. Broad reflection characteristics of the GaAs substrate enabled attitude determination for a wide-angle range, and determination around normal would be erroneous.
Journal Article
Optical Wireless Power Transmission Using a GaInP Power Converter Cell under High-Power 635 nm Laser Irradiation of 53.5 W/cm2
Optical wireless power transmission (OWPT) system is a technology that supplies energy from remote locations, having some features such as long-distance transmission, high directivity, and no electromagnetic noise interference. This study investigated the optical transmission efficiency and photoelectric conversion efficiency with a transmission distance of 10 m using GaInP power converter cells with a small area of 2.40 × 2.40 mm2 and a 635 nm high-power laser over 50 W/cm2. As a result, we achieved a photoelectric conversion efficiency of 44.7% under 6.7 W/cm2 (0.14 W) and 37.2% under 53.5 W/cm2 (1.1 W) irradiation. These results suggested that W-class optical wireless power transmission could be realized by expanding the converter cell area. Additionally, it was found that the reductions of the divergence angle of the laser and the heat generation of the power converter cell were critical issues for further lengthening the distance and increasing the power.
Journal Article