scholarly journals Limitations of wireless power transfer technologies for mobile robots

2019 ◽  
Vol 6 (2) ◽  
pp. 175-189 ◽  
Author(s):  
Wei Chen Cheah ◽  
Simon Andrew Watson ◽  
Barry Lennox
Keyword(s):  
Energy Density ◽  
Mobile Robots ◽  
Wireless Power Transfer ◽  
Alternative Solution ◽  
System Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Global Challenges ◽  
Viable Solution ◽  
Significant Research

AbstractAdvances in technology have seen mobile robots becoming a viable solution to many global challenges. A key limitation for tetherless operation, however, is the energy density of batteries. Whilst significant research is being undertaken into new battery technologies, wireless power transfer may be an alternative solution. The majority of the available technologies are not targeted toward the medium power requirements of mobile robots; they are either for low powers (a few Watts) or very large powers (kW). This paper reviews existing wireless power transfer technologies and their applications on mobile robots. The challenges of using these technologies on mobile robots include delivering the power required, system efficiency, human safety, transmission medium, and distance, all of which are analyzed for robots operating in a hazardous environment. The limitations of current wireless power technologies to meet the challenges for mobile robots are discussed and scenarios which current wireless power technologies can be used on mobile robots are presented.

scholarly journals Maximum efficiency solution for capacitive wireless power transfer with N receivers

2020 ◽  
Vol 7 (1) ◽  
pp. 65-75 ◽  
Author(s):  
Ben Minnaert ◽  
Mauro Mongiardo ◽  
Alessandra Costanzo ◽  
Franco Mastri
Keyword(s):  
Impedance Matching ◽  
Cross Coupling ◽  
Wireless Power Transfer ◽  
Maximum Efficiency ◽  
System Efficiency ◽  
Single Variable ◽  
Power Transfer ◽  
Wireless Power ◽  
Multiple Devices ◽  
Single Receiver

AbstractTypical wireless power transfer (WPT) systems on the market charge only a single receiver at a time. However, it can be expected that the need will arise to charge multiple devices at once by a single transmitter. Unfortunately, adding extra receivers influences the system efficiency. By impedance matching, the loads of the system can be adjusted to maximize the efficiency, regardless of the number of receivers. In this work, we present the analytical solution for achieving maximum system efficiency with any number of receivers for capacitive WPT. Among others, we determine the optimal loads and the maximum system efficiency. We express the efficiency as a function of a single variable, the system kQ-product and demonstrate that load capacitors can be inserted to compensate for any cross-coupling between the receivers.

An investigation on frequency characteristics of wireless power transfer systems with relay resonators

2017 ◽  
Vol 36 (6) ◽  
pp. 1594-1611 ◽  
Author(s):  
Jiali Zhou ◽  
Bo Zhang ◽  
Dongyuan Qiu
Keyword(s):  
Wireless Power Transfer ◽  
Frequency Characteristics ◽  
Maximum Power ◽  
Total System ◽  
System Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Critical Coupling ◽  
Content Type ◽  
Coupling Conditions

Purpose This paper aims to analyze the frequency characteristics of wireless power transfer (WPT) systems with relay resonators in terms of the power delivered to the load and system efficiency. Based on the analytical results, system parameters can be optimized to achieve maximum power transfer and higher system efficiency. Design/methodology/approach Based on Kirchhoff’s voltage law equations, WPT systems with relay resonators are described by the coupled linear second-order differential equations. Splitting frequencies are estimated by using the matrix theory. In addition, critical coupling conditions are demonstrated based on discriminant analysis. Findings It was found that multi-maximum values exist for the power delivered to the load and total system efficiency owing to multiple eigenfrequencies of the system. Also, frequency conditions of maximum power transfer and system efficiency, as well as their critical coupling conditions, were quantitatively estimated. Research limitations/implications During our analytical process, we assume that quality factors of resonators in the system are high and the crossing coupling between resonators is negligible. Originality/value In previous works, the exact analysis of frequency characteristics is limited to WPT systems with two resonators. The appealing feature of this work lies in its ability to present a simplified analytical method with negligible approximation errors for WPT systems with relay resonators.

scholarly journals Capacitive Wireless Power Transfer with Multiple Transmitters: Efficiency Optimization

Energies ◽  
2020 ◽  
Vol 13 (13) ◽  
pp. 3482
Author(s):  
Ben Minnaert ◽  
Alessandra Costanzo ◽  
Giuseppina Monti ◽  
Mauro Mongiardo
Keyword(s):  
Maximum Output Power ◽  
Cross Coupling ◽  
Wireless Power Transfer ◽  
Maximum Efficiency ◽  
Maximization Problem ◽  
Maximum Output ◽  
System Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
The Cross

Wireless power transfer with multiple transmitters can have several advantages, including more robustness against misalignment and extending the mobility and range of the receiver(s). In this work, the efficiency maximization problem is analytically solved for a capacitive wireless power transfer system with multiple coupled transmitters and a single receiver. It is found that the system efficiency can be increased by adding more transmitters. Moreover, it is proven that the cross-coupling between the transmitters can be eliminated by adding shunt susceptances at the input ports. Optimal values for the input currents and receiver load are determined to achieve maximum efficiency. As well the optimal load, the optimal input currents and the maximum efficiency are independent on the cross-coupling. By impedance-matching the internal conductances of the generators, the maximum-efficiency solution also becomes the one that provides the maximum output power. Finally, by expressing each transmitter–receiver link with its kQ-product, the maximum system efficiency can be calculated. The analytical results are verified by circuital simulation.

scholarly journals Practical Model for Metamaterials in Wireless Power Transfer Systems

2020 ◽  
Vol 10 (23) ◽  
pp. 8506
Author(s):  
Jingying Liu ◽  
Zhi Gong ◽  
Shiyou Yang ◽  
Hui Sun ◽  
Jing Zhou
Keyword(s):  
Resonance Frequency ◽  
High Frequency ◽  
Near Field ◽  
Low Frequency ◽  
Wireless Power Transfer ◽  
System Efficiency ◽  
Power Transfer ◽  
Wireless Power ◽  
Electric Circuits ◽  
Practical Model

Metamaterials (MTMs) with extraordinary electromagnetic properties are recently applied to wireless power transfer (WPT) systems to improve power transmission efficiency. Although theoretical progress has been made on MTMs in low frequency near field, in the operation frequency of most WPT systems (usually MHz), the design of MTMs still utilizes the model used in high-frequency applications. Therefore, a practical model of MTMs in low MHz band is proposed in this work. The resonance frequency and quality factor are used to describe the characteristics of an MTM slab. The near field WPT systems with MTMs are then modeled as electric circuits, the system efficiency is explicitly deduced, and optimization algorithms are employed to optimize the MTM resonance frequency and maximize the system efficiency. The proposed practical model is validated via a prototype wireless power transfer system operating at 6.78 MHz. Experiments show that the proposed MTM model has good accuracy for low MHz WPT systems compared with the high-frequency model. The proposed practical model of MTMs provides an accurate way to analyze the performance of MTM at low MHz frequencies and greatly benefits the future exploitation of MTM-based low-frequency near field applications.

scholarly journals Wireless Power Transfer System for Mobile Robots via Magnetic Resonant Coupling with Impedance Matching

2022 ◽  
Author(s):  
Wataru HIJIKATA ◽  
Toshiki Ohori ◽  
Xiang Li ◽  
Hideyuki Nakanishi ◽  
Shigeki Ozawa
Keyword(s):  
Mobile Robots ◽  
Input Impedance ◽  
Impedance Matching ◽  
Wireless Power Transfer ◽  
Power Transfer ◽  
Wireless Power ◽  
Resonant Coupling ◽  
Transmitter Coil ◽  
Wireless Power Transfer System ◽  
Good Agreement

Abstract Wireless power transfer via magnetic resonant coupling can be used to supply power to a mobile robot within a few meters of a transmitter coil. However, when the robot moves or its power consumption fluctuates, its input impedance varies and causes power reflection. Therefore, we propose the use of a driver coil on the transmitter side to match the input impedance. The input impedance is matched and power reflection is eliminated by regulating the coupling coefficient between the driver and the transmitter. During experiments, the transmitting efficiency showed good agreement with the calculated value, and the input impedance was matched under varying distances and load resistances. Therefore, the proposed system was demonstrated to solve the power reflection problem in mobile robots.

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