Magnetic cores for inductive wireless power transfer (WPT) have many applications and regularly uses E, U, pot and planar/circular shape coils. The systems for wireless energy transfer are not conveniently in the power levels required for some applications, as for the Electric Vehicle (EV) for instance, and there is a necessity to study different coil geometries to improve its efficiency and decrease its volume and weight. In this paper, is presented a new hexagonal-geometry coil design placed in the secondary of a WPT, and the tests demonstrate that a Type-II system compliance requirements (SAE J2954) can be accomplished with greater efficiency and lighter weight compared to circular coil. Finite element analyses accurately allow predicting the mutual inductance and achieving the optimal coil parameters and an experimental setup allows obtaining a rated power output of 7.7 kW operating at 85 kHz. The experimental testbed comprises a series-series resonance compensation circuit, a spiral coil used as primary, the proposed hexagonal pad for the secondary coil, and an AC-output, half-bridge inverter as source, achieving a lighter and efficient system in a realist scenario.

In this paper, a new direct AC/AC active-clamped half-bridge converter feeding a series-series compensated inductive charging system is proposed. The proposed converter eliminates the rectification stage, resulting in an actual single-stage (AC-to-AC) conversion with less the number of switching devices. Furthermore, it avoids the use of bulky life-limited electrolytic DC-link capacitors. The operation principles, steady-state analysis, and design considerations of the proposed converter are presented in detail. Moreover, a new predictive dead-beat technique for grid current control and a linear average charging current controller are developed for the proposed converter, which enables the unity power factor and charging current regulation. The performance of the proposed battery charger is validated through experimental results on a 1-kW FPGA-controlled Silicon carbide (SiC) based laboratory prototype.

A link-independent hybrid wireless power transfer system (HPT) that uses both capacitive and inductive action for autonomous vehicle charging application is presented in this article. A three-leg inverter topology is utilized here. Two legs of the inverter, switched at 85 kHz, are used for inductive wireless power transfer (IPT) and the third leg, switched at 1 MHz, is used for capacitive wireless power transfer (CPT). The three-leg inverter module is realized using SiC and GaN switches. The dual switching frequency operation of the converter enables independent compensation techniques to be adopted for IPT and CPT, bringing the modularity feature in the HPT. The circular inductive-link outer diameter is 460 mm and the parallel plate capacitive-link dimension is 600 mm × 600 mm. The power transfer distance or air gap is 100 mm between both links. The output power ratio of IPT to CPT is 2:1. The effectiveness of the proposed topology is validated experimentally. The advantages of this HPT system are modular-link architecture, improved misalignment performance, and distinct frequency of operation for each link that allows the inductive link to meet the SAEJ2954 standard frequency limits compared with the existing HPT systems proposed for electric vehicle charging to support autonomous mobility.

The acquisition of inductive power transfer (IPT) technology in commercial electric vehicles (EVs) alleviates the inherent burdens of high cost, limited driving range, and long charging time. In EV wireless charging systems using IPT, power electronic converters play a vital role to reduce the size and cost, as well as to maximize the efficiency of the overall system. Over the past years, significant research studies have been conducted by researchers to improve the performance of power conversion systems including the power converter topologies and control schemes. This paper aims to provide an overview of the existing state-of-the-art of power converter topologies for IPT systems in EV charging applications. In this paper, the widely adopted power conversion topologies for IPT systems are selected and their performance is compared in terms of input power factor, input current distortion, current stress, voltage stress, power losses on the converter, and cost. The single-stage matrix converter based IPT systems advantageously adopt the sinusoidal ripple current (SRC) charging technique to remove the intermediate DC-link capacitors, which improves system efficiency, power density and reduces cost. Finally, technical considerations and future opportunities of power converters in EV wireless charging applications are discussed.

A practical approach in modeling a capacitive wireless power transfer (CPT) system that utilizes an electrostatic field for the power transfer is presented in this article. The reduced capacitance model (RCM) is derived from the conventional six capacitance model (SCM) for the CPT system in view of the large charging area applications, such as electric vehicle charging. The effect of the same side and cross-coupling capacitances diminishes when the separation distance between the same side plate pair is large enough, and the reduced capacitance model (RCM) is obtained. A bipolar capacitive-link dispersion distance proposed in this article acts as an indicator to decide the use of RCM or SCM depending on the application. Furthermore, RCM attains unity voltage gain and load-independent operation at the designed single resonant frequency, unlike the SCM, where the influence of multiple resonant frequencies is predominant. An experimental validation is performed to determine the effectiveness of the RCM.