Wireless power transfer for electric vehicle at the kilohertz band

Abstract

Wireless power transfer (WPT) technology has attracted considerable attention in recent years, and there have been numerous reports about this technology. This has led to ambiguity over the actual state of WPT technology for electrical vehicles (EV) in Japan. Therefore, this paper describes the WPT technology using the kilohertz band for EVs available in Japan. WPT requirement for EV, circuit topology, coil types, control method, component, foreign object detection, and dynamic charging in Japan are summarized in this study. Power transmission distance Power transmissiondistance [21] is defined as the distance between the power transmission side coil and the ground surface. Since the minimum ground clearance varies depending on whether the vehicle is a passenger car or an SUV, the power transmission distance is set separately between 100 and 250 mm in three zones. Transmission power Transmission power [21] isdefined as an AC input power of 3.7, 7.7, and 22 kW assuming a passenger car, medium vehicles, and large vehicles, respectively.

Review on Stationary CPT Technologies and Coil Designs for EVs

“…With the same methodology, a battery hybrid energy storage system was also studied by this research group, by which it is claimed that both the transmission side power control configuration and the receiving antenna side controller were designed to achieve satisfactory power charging without communication units between transmitting and receiving antennas [18]. However, the Tokyo University research team turned to study the CPT systems in a loosely coupled frequency range in the order of kilohertz [19] rather than megahertz anymore since about 2014. More practically in laboratory and realistically in applications this time, the researchers mainly investigated the circuit topologies, transmission coil types, control methods and capacitor compensations in depth, pointing out that the effectiveness of magnetic resonance to the wireless power transfer coupling purpose and proving that the new methodology contributes more to the system efficiency and power transfer rating issues [20] with results of 40-90% and 60W, respectively.…”

“…An innovative structure design shown in Figure 17 was proposed by a team in Japan in 2015. This mixed-typed coil design [19] is supposed to allow higher tolerance to misalignments, smaller size and more compact installation for energy receiving side on EVs as two coaxial square solenoid coils on the transmitting side are expected to generate stronger magnetic field in order for the circular receiving coil to capture more amount of magnetic flux lines. Expectedly, the overall coil magnetic flux distribution of the CPT system could be boosted when compared with a pure circular coil design for the same size of chassis of EVs.…”

Design and implementation of dual‐source ( WPT + PV ) charger for EV battery charging

“…The shape of these coils can be circular, square or rectangular, and the pair may also differ in symmetry 15 . To achieve higher performance for mid‐range IPT as in the case of EV battery charging, the reactive nature of these two coils is compensated with compensation capacitors 16 . Compensated coils attain ideally zero resistance due to which the copper losses, reactive power and voltage drops are reduced in the two coils.…”

Thin, stretchable, universal wireless power transfer system for electric vehicle charging

“…Meanwhile, the methods of charging are always researched to improve performance and convenience. [5][6][7][8][9] The wireless power transfer systems which have demonstrated many advantages such as wirelessness, and being waterproof, dustproof and weatherproof are gaining considerable attention for pure and plug-in hybrid electric vehicles. [10][11][12][13] The main scheme of wireless charging is usually to install the transmitting coil and module on the ground and the receiving coil on the chassis of the vehicle.…”