Wireless charging technology has become an important development trend in future electric vehicle (EV) power supply technology due to its safety, flexibility, and convenience. With its industrialized development, interoperability has become an essential technical link. The interoperability of wireless charging systems refers to the ability of output performance to meet specified indicators when different transmitter and receiver devices are matched. This study reviews the research status of the interoperability of EV wireless charging technology. First, the definition and composition of the interoperability of wireless charging systems are briefly given. Then, the article provides a review of standards about interoperability so far. The interoperability of various magnetic couplers and compensation topologies is also analyzed and summarized. After that, the paper reviews the existing interoperability evaluation methods. Finally, this work highlights the existing problems and challenges in current research of interoperability. We hope that this work will contribute to the further development of EV wireless charging technology.

In this paper, a novel magnetic coupler of wireless power transfer (WPT) system for the solar wing driving of the spacecraft is designed. Compared with the traditional slip-ring power supply, the proposed magnetic coupler is characterized by non-contact, high efficiency, wear-free, safety and reliability. Particularly, it can be applied to the rotating condition. To realize light-weight and small-volume of the receiver, the magnetic coupler has been optimized from both compensation topology and coil configuration. Firstly, a Series-None (S-0) topology is employed to eliminate the bulky secondary-side compensation capacitor. Secondly, a new nested solenoid coil with strip core (SCSC-type) is proposed to ensure miniaturization, stable power transfer and high efficiency. Finally, the experimental setup is built to verify the performance of the designed magnetic coupler. Experimental results are well-matched to simulations, demonstrating that the weight of the prototype is 1.3 kg and the transfer power is 3 kW at an AC-DC efficiency of 92.7%.

Wireless power transfer (WPT) systems have attracted much attention because of their safety, convenience and environmental friendliness. For wireless supercapacitor charging, the system efficiency and charging current are highly dependent on the load that varies over a wide range. In this paper, a simultaneous maximum system efficiency (MSE) tracking and constant current (CC) charging control scheme for a supercapacitor is proposed. For CC charging, a double-sided LCC (DS-LCC) topology is chosen due to its characteristic of providing a load-independent output current. Furthermore, the impact of the coil internal resistance on the system characteristics (especially the charging current) is investigated, so a semi-active rectifier is introduced on the secondary side to achieve accurate CC charging and improve the system robustness. Based on the variable-step perturbation and observation (VS-P&O) algorithm, the MSE is tracked by searching for the minimum system input DC current using a primary-side Buck converter on the premise that the charging current reaches its target value. The above two control loops are independent, and the mutual communication is unnecessary when they cooperate; thus, the system is simplified. The simulation and experimental results show great consistency with the theoretical analysis. The experimental system maintains the MSE of 86% during charging the supercapacitor from 20V to 50V with 2 A.

Wireless charging for electric vehicles has been investigated in recent years. One of the critical issues of the research is to improve the weak interoperability between two popular charging pads—rectangular pad (RCP) and double-D pad (DDP). This article intends to model the interoperability under pad misalignment and improve it by adjusting the pads’ relative position. First, the variation of interoperability with pad misalignment is analyzed by the flux model. Full output power and high transmission efficiency can be achieved when the two pads are misaligned to a certain distance. Second, the optimal misalignment is obtained by flux calculation and simulation. Third, an adaptive position adjustment method for the transmitting pad based on the variable-step perturbation and observation algorithm is proposed. By searching the maximum dc input current, the optimal position of the transmitting pad can be found. Finally, in the experiment, a 3.3 kW output with 95% coil-coil efficiency is realized when the RCP and DDP interoperate at the optimal position. Compared with the scenario without position adjustment, the improvement of output power and efficiency proves that the proposal can optimize the interoperability between the RCP and DDP.

The operating temperature of the magnetic coupler in wireless power transfer (WPT) systems for electric vehicles (EVs) determines the system reliability and service life. This paper studies the modeling and analysis of temperature characteristics of a general magnetic coupler. Firstly, a thermal circuit model is established to show the heat transfer of the magnetic coupler in the air. Secondly, the heating mechanism of the coil, core and aluminum (Al) shield plate is studied. The thermal power of each component is calculated, and the temperature distribution is qualitatively given based on the proposed thermal circuit model. Then, the temperature distribution of each component is simulated, and the results are consistent with the theoretical analysis. Finally, a 6.6 kW WPT prototype is set up, and the temperature of each component is measured after 30 minutes of operation. The temperature of the coil, 34.6 °C, is the highest among that of the coil, core, Al plate and coil base. The agreement between experimental results and the theoretical simulation results shows that the thermal field simulation can accurately predict the temperature of the magnetic coupler by reasonably setting the thermal power addition method.