This paper proposes a modular magnetic integration design for EV wireless power transfer (WPT) systems such that the magnetic field generated by the compensation and transmitting coils are exploited to enhance the power transmission capacity. An integrated coil along with a compensation method are proposed to enable magnetic field enhancement without any reactive power flow between the compensation and the transmitting coils, and to achieve input zero phase angle (ZPA) and constant current (CC) output. The proposed design offers misalignment tolerance to stabilize the system output under any random misalignment. The feasibility of the proposed topology is investigated through the equivalent circuit modeling and analysis. A finite element analysis (FEA)-based optimization algorithm is also developed to expedite the design process without compromising the accuracy. Analytical and simulation results confirm the advantage of the proposed design in eliminating the leakage magnetic field while enhancing the transmission flux density. Finally, a scaled-down WPT prototype is built and tested to verify the performance and effectiveness of the design. This work provides insights into possible modular integration design of the high-order compensation topologies featuring higher compactness, magnetic field enhancement, reduced leakage field, and misalignment tolerance for WPT system.

This article presents a cost-effective dynamic wireless power transfer (DWPT) system for efficient and stable output power charging of autonomous moving equipment. The proposed system is realized based on a low-cost segmented configuration and a flexible operating strategy. Specifically, the configuration is a combination of a dynamic T -series/series topology and extended transmitter (Tx) coils. The topology eliminates the cross-coupling impact of adjacent Tx coils and tunes the dynamic circuits at resonance. It makes the switching circuits equivalent to a unified analytical model for simplified control, which reduces the cost of inverter, decoupling, compensation, and position detection in the DWPT. The extended Tx coil with a simplified structure, which is obtained from winding coupling characteristics and a finite-element analysis based algorithm, is proposed to improve the moving misalignment tolerance, thereby reducing the number of Tx segments. An operating principle with three modes behind the proposed strategy is designed to fully utilize the efficient coupling area of individual Tx segment and improve the efficiency in the transition region from one segment to the other one. The operating parameters including the transition and compensation are obtained based on the topology and its operating principles. Position detection and power regulation methods are developed and embedded in the system control to configure/coordinate the segmented coils as the strategy and mitigate power fluctuation in the transition region. The performance and effectiveness of the proposed cost-effective DWPT system are evaluated based on experimental results on a scaled-down prototype.

This paper presents a quasi-uniform magnetic coupling based effective-configuration wireless power transfer (WPT) system for drones wider-area charging with multiple extended transmitter coils. The extended transmitter coil with two windings is proposed to cooperate with a small receiver coil for misalignment tolerance with efficient and quasi-uniform coupling. The extended coil is worked out by a simulation-based algorithm, which can be implemented by simple and low-cost procedures. Independent-operating multiple extended coils are designed with overlaps and a dynamic topology for low-cost and robust charging area extension according to performance analyses. Moreover, a novel landed position detection method based on the negative coupling characteristic of the extended coils is proposed for system configuration. The design enables cost-effective charging area extension, and assists to sense the position of drones. A prototype is established with a charging area nearly 20 times the area of the receiver coil. Experimental results prove the feasibility of the design, which can be applied flexibly.

In this article, an optimized design for a dual-coupled inductor–capacitor–capacitor-series ( LCC -S)-compensated wireless power transfer (WPT) system with zero-phase angle (ZPA) input condition and load-independent constant current (CC) output is presented. To this end, based on the misalignment characteristics of the reversed-series compensation coil structure, a novel design method for determination of the compensation parameters is proposed. By introducing a stability factor, any restriction on the variation correlation of the mutual inductances between the transmitter and receiver coils, and between the compensation and receiver coils within the range of misalignment tolerant design, is eliminated, thereby increasing the degree of freedom in the coil structure. According to a predetermined misalignment tolerant range, the proposed method can limit the fluctuation of the output current within a certain range and maintain the ZPA input condition. A 200-W/85.3-kHz prototype based on the proposed method is implemented and its performance is experimentally validated. The system can operate in ZPA input and load-independent CC output with a misalignment tolerance factor of 4, as the load varies from 5 to 20 $\Omega$ .

Load-independent constant current (CC) outputs are desirable in many applications of wireless power transfer (WPT). Yet the WPT gain of a conventional system is normally dependent on the magnetic components such as coils or inductors, making it difficult to customize the output for interoperability. This article presents a gain variable WPT topology for CC output customization, which only employs capacitance tuning to provide sufficient freedom in gain regulation. To break the gain limitation of S - S compensation, which is the simplest with gyrator characteristics for CC output, a capacitive or inductive component is paralleled to the coil as SP - S or S - PS compensation. A thorough analysis based on the Y-Δ transform indicates that the gain is restrictively variable with the parallel component. An S - CLC -compensated topology without an independent inductor is further proposed to avoid those restrictions with as few additional components as possible. The inductor in the topology, coupled with the transmitter coil and integrated into the receiver coil, extends the gain variable range. A complete design process of the topology is presented to realize efficient WPT and CC output customization with a wide variable-gain range and misalignment tolerance. Analytical and simulation results confirm the effectiveness of the gyrator-gain variation by capacitance tuning. Finally, the performance of the WPT topology is evaluated by experimental results on a scaled-down prototype.

Wireless power transfer (WPT)-based voltage equalizers (VEs) are desired for flexible and secure balanced charging of unmanned aerial vehicles (UAVs). However, the existing WPT-based VEs fail to balance the cells once the onboard receiver (Rx) is away from the transmitter (Tx), and the efficiency and capacity are limited. This article proposes a reconfigurable WPT-based multiport hybrid charging approach to achieve UAV’s cell string balancing under multiple states. By converging one Tx port, one Rx bidirectional port, and two voltage-balance (Vx) driving ports, the approach enables the source-to-cell (STC) and pack-to-cell (PTC) charging/balancing, which achieves cell balancing during charging, discharging, and standing conditions. Circuit analyses of the corresponding topology validate its operating principles and basic performance. Efficiency and capacity in the STC balance mode are improved with the combined Rx and Vx output ports. The cell’s voltage equivalation can still be realized without Tx in the PTC balance mode. Asymmetric Tx and Rx coils and orthogonal Vx coils integrated into Rx are designed with specific coupling or decoupling as the multiport WPT coupler to enable the charging and balancing with a robust misalignment tolerance. An experimental prototype for eight cells is established, and the test results demonstrate the effectiveness of this scheme.