This paper proposes an autonomous coil alignment system (ACAS) for electric vehicles (EVs) with dynamic wireless charging (DWC) to mitigate the reduction in received power caused by lateral misalignment between the source and load coils. The key component of the ACAS is a novel sensor coil design, which can detect the load coil’s left or right position relative to the source coil by observing the change in voltage phase. This allows the lateral misalignment to be estimated through the wireless power transfer (WPT) system alone, which is a novel tracking method for vehicular applications. Once misalignment is detected, the vehicle’s lateral position is self-adjusted by an autonomous steering function. The feasibility of the overall operation of the ACAS was verified through simulation and experiments. In addition, an analysis based on experimental results was conducted, demonstrating that 26% more energy can be transferred during DWC with the ACAS, just by keeping the vehicle’s load coil aligned with the source coil.

Capacitive power transfer (CPT) system can be employed for wireless charging of drone applications. However, in the CPT system, cross-coupling capacitance caused by coupling of the two pairs of plates on different sides, which do not form the main capacitance must be considered. Designs that do not properly consider the cross-coupling capacitance can cause decrease in the efficiency of the system. In this article, we propose a separate circular capacitive coupler for the CPT system. To reduce the cross-coupling capacitance in drone applications, the plates on the same side are separated. The circuit model of the coupler is presented; it considers a total of six coupling capacitances. For maximum power transfer efficiency, impedance of the receiver is considered to determine the parameter value of the LC resonance. Through simulation and measurement, we verified that the proposed separated circular coupler can reduce the cross-coupling capacitance. The plate-to-plate power transfer efficiency is maintained at 89.4% with 100-W output power.

The paper proposes a method for locating an electric means of transportation such as electric vehicles that adopts dynamic wireless charging system. The method works with magnetic wireless power transfer systems, based on a ferrite core counting approach. The ferrite core counter system operates by counting all the ferrite cores of the source coils used for guiding the magnetic field in a magnetic wireless power transfer system. The proposed ferrite core counter has a position detection accuracy equivalent to the spacing of the ferrite cores. In addition, this paper proposes a ferrite position identification (FPID) messaging unit to correct ferrite core counter errors. FPID blocks which are successively placed under the source coil are recognized by the ferrite core counter, and their passage is reported as a sort of message in the vehicle. This FPID messaging unit provides the ferrite core counter with a system that can correct errors in the number of ferrite cores counted. The effectiveness of the vehicle positioning system with the ferrite core counter and the FPID messaging unit has been demonstrated through simulation and experiments.

Wireless power transfer (WPT) is being developed to supply electric power to electric trains, using a source coil in/on the railway track and a pick-up coil on the train. A number of benefits can be obtained by eliminating the catenary and pantograph currently used for railway electric power supply. However, the WPT employs coils, and the electromagnetic field generated by the WPT can interfere with conventional train detection methods, such as track circuits and RFID, installed on the tracks. Train position information is critical for railway operation, especially for high speed trains. This paper proposes a novel system which provides train position information using a source coil segment. It consists of onboard sensor coils, ferrite blocks designed using specific position information, and a detector. The proposed system can be implemented using the source coil and load coil of the WPT. Information about the train's relative position is obtained by the detection of ferrite blocks distributed within the source coil segment. The train position information provided by the ferrite components is detected by onboard sensor coils and a detector. The proposed ferrite position identification (FPID) system provides accurate train position information and is not affected by WPT electromagnetic interference. The operating principles of the FPID system are presented in detail. The performance of the proposed FPID system was measured by simulations and experiments.

Wireless power transfer (WPT) technologies are currently growing in popularity because of problems with batteries in portable devices, such as the added weight and the inconvenience of conventional wired charging methods. However, wireless charging systems generate leakage magnetic fields, causing malfunctions in adjacent electronic devices. Technologies to suppress electromagnetic interference (EMI) from portable WPT systems are required to prevent this problem. In this paper, we propose a topology design for a multiresonance reactive shield to suppress the EMI from WPT systems. The proposed shield employs closed loops, which are located peripheral to the WPT coil and resonance matching capacitor. The power efficiency and shielding performance of the proposed method were compared with those of the conventional WPT system coil shielding topologies. The proposed shield exhibited about 27.37 dB more 3rd harmonic EMI suppression than other methods while maintaining higher power transfer efficiency.

In this article, a microrobot capable of creating propulsion force and receiving electrical energy using a wireless power transfer (WPT) system is proposed. As a source of propulsion and rotation for the microrobot, we use the force and torque of magnetic material in a time-variant magnetic field generated by the transmitting coil of the WPT system, with a specifically designed magnetic material which produced even greater force under the same volume. While microrobot propulsion based on the Lorentz force is closely related to the magnitude of the induced current, because the force of the magnetic material in the proposed design is independent of the induced current, it is more practical for miniaturization of the microrobot. Additionally, the proposed model is able to use the LC resonance frequency, and a magnetic material located in the receiving coil introduces a higher coupling coefficient between the transmitting coil and the receiving coil. These characteristics make the proposed microrobot suitable for powering through a WPT system. The feasibility of the proposed model was initially investigated by theoretical analysis and then verified in simulation and an experiment. In the experiment, the fabricated microrobot $4.5\times 2.0\times2.0$ mm ³ in size achieved a power transfer efficiency rate of 4.5% at 103 kHz with a propulsion speed of 7.5 mm/s and rotating motion.