Compensation topologies play an essential role in wireless power transfer (WPT) systems for electric vehicles (EVs). Specifically, the double-sided ${LCC}$ compensated (DS- ${LCC}$ ) topology has been widely adopted, owing to its inherent advantages, such as load-independent constant current (CC) output, low sensitivity to load variation, and high freedom in parameter design. However, large resonant devices in the DS- ${LCC}$ topology lower the system efficiency and increase the complexity of optimal parameter tuning. Therefore, in this study, the parameters of the DS- ${LCC}$ compensation topology are reconfigured by adjusting the ratios of its two compensation inductances without changing the specified system-level parameters, such as the loosely coupled transformer (LCT), operating frequency, and specified CC outputs. The system performance under each case is analyzed and compared in detail, based on which, an asymmetric parameter-design method is proposed to optimize the system efficiency. To verify the reasonability of the proposed tuning method, a 6.6-kW experimental prototype is configured, and comparative experiments are conducted. The experimental results indicate that, compared with the conventional method, the proposed parameter-tuning method improves the system efficiency under overall load conditions, especially under light loads.

The use of wireless power transfer technology in unmanned aerial vehicle (UAV) systems is rapidly improving in different application areas. The main limitations of electric-powered UAVs are their charging range and stability in dynamic conditions. To solve these, this paper proposes a hybrid control method based on DC-link and switched capacitor control with a fixed operating frequency. The DC-link voltage is regulated by the boost PFC converter to smoothen the output voltage, and the switched capacitor is used to dynamically compensate for self-inductance variations under dynamic coupling conditions. The output voltage stabilization and near-unity power factor of the input impedance can be achieved by applying the hybrid control method. Therefore, efficiency improvement can be achieved. Furthermore, the proposed control method can also be applied to systems with large coupling variations. To verify the proposed control method, a 500-W prototype was set up in the laboratory, and the experimental results proved that the control method could ensure a stable output voltage with horizontal and vertical offsets of 200 mm and 62 mm respectively. Additionally, the results show that the maximum efficiency of the proposed control method is 91.9%, demonstrating that the proposed method effectively improves the efficiency.

This letter proposes a simplified integration system of bidirectional on-board chargers (OBC) and wireless power transfer (WPT) charging systems for electric vehicles. The proposed system reduces the cost, weight, and volume of the power conversion units by sharing active switch bridges and magnetic coupler coils without mechanical switches. The proposed magnetic coupler design method enables the secondary coil to be shared in both OBC and WPT modes, while the primary coil for OBC can be magnetically decoupled from the transmitter coil in WPT mode. Based on the proposed topology configuration and winding method, the proposed system operates as a dual-active bridge and an inductor-capacitor-capacitor-series (LCC-S) compensated converter in the OBC and WPT modes, respectively. To validate the proposed integrated OBC and WPT charging system, a prototype with a 3.3-kW OBC and WPT system is configured and verified through experiments.

This letter proposes a reconfigurable LLC resonant converter for bidirectional electric-vehicle chargers. The proposed converter can achieve the monotonic voltage gain curves of a unidirectional LLC resonant converter in both charging and discharging modes by designing the resonant inductors using a coupled inductor and the structure of the windings in the transformer. To validate the proposed converter, a 3.6-kW experimental prototype was configured. Results showed that it achieved maximum efficiencies of 96.86% and 95.95% in the charging and discharging modes, respectively.

This article presents the design methodology for a bidirectional CLLC resonant converter with dual resonant frequencies for charging a wide range of battery voltages. The proposed design method improves the battery-charging voltage range by operating at two resonant frequencies with constant current and constant voltage regardless of load variations. Furthermore, the proposed design method improves the conversion efficiency and simplifies the controller because it operates at fixed resonant frequencies. To validate the proposed design method, a 3.6-kW experimental prototype is configured. Experimental results show that compared with the conventional method, the proposed design method improves the efficiency by approximately 3.13% under light load conditions, and the measured maximum efficiency in the charging and discharging modes is 98.04% and 98.05%, respectively.

This article presents a novel integrated on-board charger (OBC) and low-voltage dc–dc converter (LDC) system to improve the cross-regulation performance of electric vehicles. The proposed system improves the cross-regulation performance of OBC and LDC by using the magnetically decoupled OBC and LDC windings of a single transformer. Based on the above winding structure of the transformer, the proposed system operates as a dual active bridge converter for OBC and an inductor-inductor-capacitor (LLC) resonant converter for LDC without additional devices, resulting in an improvement in cross-regulation performance. Furthermore, it inherently mitigates the unintended high-voltage problem on the input dc-link capacitor caused by the multiwinding transformer in the LDC standalone mode without any additional control method. To validate the proposed system, an experimental prototype with an integrated 3.3-kW OBC and 1.0-kW LDC is configured and tested.