Contactless Power Transfer Research Articles

The Coupling Coefficient of Disk Coils for Contactless Power Transfer

The Coupling Coefficient of Disk Coils for Contactless Power Transfer

Metamaterial-enabled wireless and contactless ultrasonic power transfer and data transmission through a metallic wall

Metamaterial-enabled wireless and contactless ultrasonic power transfer and data transmission through a metallic wall

Linear generator for power supply to on-board consumers of high-speed magnetically levitated carriages

Background: Maglev transport is a promising mode of transport that can provide passenger and freight transportation at speeds of up to 400-500 km/h, and in the longer term – up to 1000 km/h. Active research in this area is being conducted in China, Japan, and the USA. Currently, in China and Japan, speeds of 450-500 km/h have been achieved for commercial transportation, and promising programs have been adopted for the construction of high-speed maglev tracks and the creation of rolling stock. At such speeds, one of the pressing problems is the problem of contactless energy transfer for on-board consumers located on the carriage, because it is very difficult to ensure reliable contact current collection at speeds of 450-500 km/h and above.
 Aim: development of the design, calculation and analysis of the characteristics of a linear generator of electrical energy for contactless power transfer to the moving crew of high-speed magnetically levitated transport.
 Materials and methods: to calculate the external magnetic field of the linear generator inductor and the EMF induced in the receiving coil of the crew, methods of electromagnetic field theory and electrical circuit theory were used; calculation algorithms are implemented in the Visual Basic for Applications software environment.
 Results: a design was proposed and the calculation of the external magnetic field of an inductor with transposition of conductors was performed; to increase the EMF induced in the receiving coil of the crew, it is proposed to give the receiving coil a double 8-shape; the most rational inter-circuit distance of the linear generator inductor has been established; the nature of the change in the magnetic flux penetrating the receiving coil when the vehicle moves, and the magnitude of the emf induced in the receiving coil are determined.
 Conclusion: the results can be used in the development of rolling stock for promising high-speed maglev transport systems.

Easy-to-install battery storage based residential power supply with contactless power transfer

Solar energy with battery storage has enormous potential for residential power supply applications. However, the installation is often complicated with lots of wiring. The wireless power transfer (WPT) interface can greatly reduce the complicated wiring part, facilitating easier installation, with additional benefits like electrical isolation, lower maintenance cost, better reliability. However, rigorous proof-of-concept of WPT for LV household power supply still remains to be largely unexplored. This work fills the research gap by presenting application of contactless power transfer system with battery storage for the solar-powered low-voltage (LV) power supply. Various resonant topologies for inductive power transfer (IPT) are studied, and a complete theoretical model of an LCL compensated IPT system integrated with a battery energy storage system is presented. The voltage and current characteristics are investigated to understand the operation of the proposed integrated IPT system at LVDC level. The setup is first realized and analysed in details in simulation using MATLAB/Simulink. Hardware experiments proves the feasibility of the contactless power transfer capability at the high efficiency of the integrated IPT battery system. The results show that the proposed system can maintain a constant load voltage of 48 V for a load variation of around 25%, with an efficiency of 92% at 85 kHz switching frequency.

Parallel Contactless Transmission of Power and Rotor Temperature of Electrical Machines via Magnetically-Coupled Resonance and Capacitive Radio Frequency

Over-temperature of the rotor may cause a series of insulation deterioration of electrical machines. In severe cases, it can lead to insulation failure and even faults, such as broken rotor bars and end ring fracture. The temperature online monitoring can effectively avoid the aforementioned insulation failure; however, the conventional temperature measurement by embedded sensors is difficult to utilize due to the power and data transmission of sensors at the rotor side. This paper proposes a contactless strategy to supply power and send rotor temperature data between the stator and rotor sides of electrical machines. With the proposed method, contactless power transfer is realized by means of magnetically-coupled resonance, while the data signal is transferred by capacitive radio frequency (RF) technology. An experimental prototype was developed and installed on a 22-kW induction motor. The results show that the embedded sensors are contactless powered effectively. At the same time clear temperature data signal can be received on the stator side without filtering, and rotor temperature can be monitored in real-time accurately.

Quasi-Synchronous Operation Principle of a Variable Air-Gap Doubly Fed Linear Motor for High-Speed Maglev Application

Compared to a long-stator linear synchronous motor (LLSM), a long-stator doubly-fed linear motor (DFLM) exhibits two distinct advantages for high-speed maglev application: 1) It has two additional degrees of freedom with both the frequency and the phase angle of the mover to improve its control accuracy and dynamic responses; 2) It can use the slip power to feed the mover contactlessly and directly. In order to achieve the propulsion, the levitation, and the contactless power transfer through the common air-gap magnetic field, the “quasi-synchronous operation (QSO)” principle of the DFLM is proposed for high-speed maglev train. Based on the DFLM modeling and distinctive constraint analysis for high-speed maglev application, the performance evaluation of the DFLM is further investigated. To validate the feasibility of the DFLM application for high-speed maglev train, a unit DFLM prototype is designed and tested, and the corresponding simulation studies of the QSO control structure are provided with the comparison to the LLSM system.

Design of Wireless Power Transfer System Based on LCC-S

Recently, wireless power transfer (WPT) technology has become a research hot spot due to its benefit of contactless power transfer. Firstly, for the sake of solving the problem of the small coupling coefficient of traditional orbital wireless power transfer systems, a new structure and control strategy of transceiver coil was proposed, and then the optimal parameters of system transmission efficiency were found out by comprehensive analysis of the LCC-S compensation circuit structure and equivalent circuit, and the correctness of the parameters was verified in MATLAB/Simulink simulation. Finally, an experimental prototype was built, and the experimental findings show that the wireless power transfer system based on LCC-S can realize voltage regulation control, the coupling coefficient is increased by 0.4 compared with the traditional orbital structure, and the transmission efficiency of this system is more than 80%.

Experimental Study of Transmission Coil Configuration for Omnidirectional Power Transfer in Magnetic Field Coupling Type Contactless Power Transfer

In magnetic field coupling type contactless power transfer, there is a problem that stable power transfer is not possible to changes in the position, angle, and distance of the transmission and receiving coils. In the case of mobile devices charging the battery using the contactless power transfer, the angle between the power transmission and receiving coils is not constant. Therefore, the power transmission efficiency is influenced by changing the position between the power transmission and receiving coils. In this study, the shape of the power transmission coils was investigated with stably supply power in all directions to mobile devices. We studied three coils consisting of cubic coil with 4 squares connected in parallel(4 squares cubic coil), cubic coil with 4 L-shapes connected in parallel(L4 cubic coil) and octagonal star prism coil with 8 square coils connected in parallel(octagonal star prism coil) . The S-parameters between the transmission and receiving coils were measured using a Vector Network Analyzer and after converting S-Parameters to Z-parameters. The theoretical maximum efficiency was obtained from the kQ product and compared with different coil shapes.

Adaptive Impedance Matching Network for Contactless Power and Data Transfer in E-Textiles.

One of the major challenges associated with e-textiles is the connection between flexible fabric-integrated wires and rigid electronics. This work aims to increase the user experience and mechanical reliability of these connections by foregoing conventional galvanic connections in favor of inductively coupled coils. The new design allows for some movement between the electronics and the wires, and it relieves the mechanical strain. Two pairs of coupled coils continuously transmit power and bidirectional data across two air gaps of a few millimeters. A detailed analysis of this double inductive link and associated compensation network is presented, and the sensitivity of the network to changing conditions is explored. A proof of principle is built that demonstrates the system's ability to self-tune based on the current-voltage phase relation. A demonstration combining 8.5 kbit/s of data transfer with a power output of 62 mW DC is presented, and the hardware is shown to support data rates of up to 240 kbit/s. This is a significant improvement of the performance of previously presented designs.

Quasi-Synchronous Operation of a Long-Stator Doubly Fed Linear Motor With Accurate Control of Both Propulsion and Contactless Power Transfer

In this article, a quasi-synchronous operation (QSO) of a doubly fed linear motor (DFLM) is proposed to achieve accurate regulation of both the propulsion and the contactless power transfer. A new control structure is proposed to achieve the loose coupling control between the stator side and the mover side, where the scalar control is used for the stator side controller (SSC), and the field-oriented control (FOC) is adopted for the mover side controller (MSC). The SSC and the MSC are with “frequency coupling,” which enhances the reliability of the whole control system with less information exchange between the SSC and the MSC. The effectiveness of the proposed design is validated through both simulation and experimental studies.

RETRACTED: A design of wet-mateable connector aiming for contactless power transfer and optical communication

At present, contact watertight connectors are commonly utilized for the connection between underwater electromechanical equipment and the seabed observation network. Such conventional watertight connectors are inevitably likely to be irreversibly worn when plugging and unplugging, besides complicated sealing structures and limited service life. This paper designs a Wet-Mateable connector aiming for Contactless Power Transfer and Optical Communication (PTOC-WMC), which is based on technology of Contactless Power Transmission (CLPT) and optical communication. Docking structure of the sockets and plugs are designed, facilitating Remotely Operated Vehicle (ROV) to operate. A prototype of the PTOC-WMC was established. The experimental results show that the connector designed can achieve 200W power transmission, with a maximum power transmission efficiency of 94%. The communication bandwidth reaches 18MHz. The PTOC-WMC can assist the rapid and safe deployment and operation of seabed observation network.

A New Scheme for Parallel Transmission of Power and Full-Duplex Mode Information Sharing with LCC Topology Based on IPT System

In this study, a full-duplex data communication module is designed and developed for sharing information in a contactless power transfer system. It is realized through LC tank circuits with an inductive power transfer (IPT) system. On both the transmitter and receiver sides, one LCC compensation topology is used. Since Phase Shift Keying (PSK) is less susceptible to error and power-efficient digital modulation techniques, this paper proposes to implement PSK digital modulation technique to data signal modulation for full-duplex communication in a wireless EV charger. The proposed scheme ensures stability, transfers load status, charging level, and emergency messages between the source and load sides of the system, and vice versa. The results are compared with the Amplitude Shift Keying (ASK) digital modulation technique. Further, the impedance-based model is developed to analyze the interference between the power and high-frequency information signals. The inductive power and data transfer (IPDT) prototype is developed in the laboratory and results show that the data rate reaches 288 kbps when 46.6 W of power is transferred from source to load.

Subcutaneous power supply by NIR-II light

Implantable medical devices are wished to be recharged via contactless power transfer technologies without interventional operations. Superior to subcutaneous power supply by visible light or electromagnetic wave, second near-infrared (NIR-II) light is predicted to possess 60 times subcutaneous power transmission but hard to be utilized. Here we report a photo-thermal-electric converter via the combination of photothermal conversion and thermoelectric conversion. It is able to generate an output power as high as 195 mW under the coverage of excised tissues, presenting advantages of non-invasion, high output power, negligible biological damage, and deep tissue penetration. As an in vivo demonstration, the output power of a packaged converter in the abdominal cavity of a rabbit reaches 20 mW under NIR-II light irradiation through the rabbit skin with a thickness of 8.5 mm. This value is high enough to recharge an implanted high-power-consumption wireless camera and transfer video signal out of body in real-time.

Modeling the optimal compensation capacitance of a giant magnetostrictive ultrasonic transducer with a loosely-coupled contactless power transfer system

Modeling the optimal compensation capacitance of a giant magnetostrictive ultrasonic transducer with a loosely-coupled contactless power transfer system

An Attended-Free, All-in-One-Go, Automatic Analysis Assistant Software for E-liked Shape Contactless Inductive Power Transfer Device

This paper presents automatic software for E-liked shaped contactless inductive power transfer (CIPT) device study and design that provides attended-free, multiple-case auto-generating and auto-deploying analysis in one go. It provides visualized and listed results in a design space or for optimizing solutions. To satisfy the demand for static and dynamic charging devices, the software provides specific cores, such as EE-, EI-, IE-, and II-shaped, with or without legs as optional core structures. The software contains three main parts: a user-friendly interface, analytic approaches providing grid analysis that represent the general performance in a designated parameter range, and optimal analysis for multi-objective optimization using a genetic algorithm (GA). The post-analysis processor converts the analysis results to easy-to-read outputs. Users can customize various parameters, such as core type, structural size, circuit configuration, materials, and analysis setting. Automatic functions, such as resistance and compensation calculation, are available for the convenience of the user. By applying one approach, or by combining them in a specific order, the software achieves designs that satisfy the user’s demands within the user-provided range. The software is built in Python and collaborates with a finite element method (FEM) solver, which is JMAG in this paper. Some examples are given to demonstrate the performance of the software.

Electric Vehicle Traction Drives and Charging Station Power Electronics: Current Status and Challenges

With the need for more environmentally friendly transportation and the wide deployment of electric and plug-in hybrid vehicles, electric vehicle (EV) charging stations have become a major issue for car manufacturers and a real challenge for researchers all over the world. Indeed, the high cost of battery energy storage, the limited EV autonomy and battery lifespan, the battery charging time, the deployment cost of a fast charging infrastructure, and the significant impact on the power grid are the origin of several research projects focused on advanced power electronics topologies and the optimization of the EV charging stations in terms of power transfer and geographical location. Three charging levels can be distinguished, which differ in terms of output power and charging time. The higher the level of charging, the faster the charging process, as more power is delivered to the vehicle at the expense of power quality issues and disturbances. Moreover, three types of charging systems can be distinguished, which are inductive recharging (contactless power transfer), conductive charging systems, and battery swapping. Additionally, EVs encompass fuel cell (FC) EVs, which uses hydrogen as primary energy resources, which is nowadays under extensive research activities in academia and industry. This review paper aims at presenting a state of the art review of major advances in power electronics architectures for EVs traction drives, and battery-based EVs charging stations. Specifically, the focus is made on light-duty electric vehicles drivetrain power electronics and charging stations specifications, the proposed power electronics solutions, the advantages and drawbacks of all these technologies, and perspectives for future research works in terms of smart EV charging and up-to-date solutions for power system disturbances mitigation.

Guest Editorial Advances in Wireless Power Transfer Technologies

Recently, application of wireless (contactless) power transfer (WPT) technology in electric transportation, smart e-mobility, and future smart cities has gained wider attention. This is evident from the use of WPT technology in electric cars and heavy-duty mass transit, unmanned aerial vehicles (UAVs/drones), sea/undersea vehicles (ships/submarines), utility vehicles (forklifts/golf carts), micromobility devices (scooters/e-bikes), and smart cities, offices, and buildings. WPT can be achieved either via electromagnetic inductive power transfer (IPT) or via electrostatic capacitive power transfer (CPT). This special section (SS) received contributions from papers that focus on the latest advances in WPT technology in the previous applications. This SS received a large number of submissions from across Asia/Pacific, Europe, Africa, South America, as well as North America. Keeping space limitations in mind, about 30% of the papers were accepted for inclusion in this special section.

Multi-focal transmission acoustic phase holograms in contactless ultrasonic power transfer systems

Using a pre-designed, simple, and cost-effective acoustic hologram alongside a single ultrasonic transducer, as an acoustic source/transmitter, enables new capabilities in multi-focal focusing, acoustic patterning, and contactless ultrasonic power transfer (UPT), to selectively charge sensors/receivers. In this work, different multi-focal holograms are designed that cover single- to four-focus acoustic patterning for UPT purposes. The holograms are numerically designed to create multi-focal pressure patterns in a target plane where an array of receivers are placed. The incident sound wave from a transmitter, after passing through the hologram, is manipulated, hence, the output field is the desired pressure field, which excites the receivers located at the pre-determined focal points more significantly. Proof-of-concept experiments are also performed for a five-element receiver setup, using a two-focus hologram, to selectively power two specific receivers. The experiments indicate a significant electrical average power output enhancement ratio of 23.4 from the targeted receivers, compared to untargeted ones, which proves the functionality of the designed multi-focal holograms in arbitrarily patterning the contactless transfer of ultrasonic power.

Transferring power and data simultaneously of different direction in ultrasonic contactless power transfer system

Ultrasonic contactless power transfer (UCPT) technology is a new kind of contactless power transfer (CPT) technology, which can be used to transfer power to loads in enclosed metal containers. In this paper, an UCPT system of transferring power and data simultaneously of different direction using only one pair of transducer is proposed. In the proposed system, power is transferred from the transmitting side to receiving side, and data is transferred in reverse direction simultaneously, from receiving side to transmitting side. The proposed system consists of power transfer channel and data backward transfer channel. The power transfer channel is modeled and the data backward transfer channel is analyzed in detail. 2ASK technology is used in data transfer channel. To show the effectiveness of the proposed system, an experimental setup is built. For power transfer channel, the output power is up to 40 W, and for data transfer channel, the data transfer rate is up to 1.6 kbps in ideal situation. When transferring a picture, the data transfer rate is 1.43 kbps and the output voltage is 5V which are realized at the same time.

Design and Analysis of a Multi-Input Multi-Output System for High Power Based on Improved Magnetic Coupling Structure

Conventional inductive contactless power transfer (ICPT) systems have only one energy transmission path, which makes it challenging to meet the power transmission requirements of high-power and reliability. This study proposes a novel multiple-input multiple-output (MIMO) ICPT system. The three-dimensional finite element analysis tool COMSOL is utilised to study various magnetic coupling structures, analyse the influence of cross-coupling between coils on the same side, design the circuit based on this, propose a parameter configuration method for resonance compensation, and, finally, build an experimental platform with small magnetic coupling structures for single-input single-output systems (SISO) and MIMO systems. The results indicate that the co-directional connection of the coils of the E-shaped and UE-shaped magnetic coupling structures has a strengthening effect on the secondary side coupling. The magnetic coupling structure of the E-shaped iron core exhibits the best transmission performance. The transmission power of the MIMO system with the E-shaped magnetic coupling structure as the core device is significantly improved. In addition, the output power is unchanged after a secondary side fault, which verifies the accuracy of the proposed method.