Mobile device charging is made possible by the dynamic wireless power transfer technology and it is developing toward higher power levels. The output power fluctuates significantly with the movement of the device due to the discontinuous coil switching and the peculiarities of the dynamic magnetic coupler, which has an impact on charging effectiveness and battery life. In this article, a three-level Buck (Buck TL) is used as a dc–dc converter at the receiver side and a composite control aiming to suppress output power fluctuations is proposed. The minimum effective suppression range for the frequency of the coupling fluctuation and the control performance in the transient state are analyzed theoretically. Compared with PI control, the simulation is built, and the 2.6 kW experiment results showed that the composite control could reduce the system output voltage ripple from 13% to 4.4% with resistive load and the output charging current ripple from 22% to 9% with battery load without impacting the efficiency of the Buck TL system, which verified the effectiveness of the proposed composite control strategy.

In this paper, a dynamic model based on sampled-data method is presented for wireless power transfer (WPT) system. The orders of derived model are equal to the orders of system. The modeling is different from the existing dynamic modeling for WPT systems, which almost double the model's order. Furthermore, the systematic analysis process is suitable for any WPT topologies and without the higher harmonics neglected and low frequency approximation. Meanwhile, the state variables are allowed to vary up to twice the switching frequency, since the half-period symmetry property is exploited. In this work the series-series (SS) compensated WPT system is chosen as an example and the large signal model and the steady state operation point are determined. The small-signal responses perturbed by the phase-shift angle, switching frequency and input voltage are obtained. The derived model is more adequate with simulation and experimental validation.

An analysis of the critical inductance and capacitor voltage ripple of bidirectional Z-source was presented in this paper. Varying inductances were found to lead to different operational modes of the inverter. The critical inductance was derived. While the Z-source capacitor voltage ripple is traditionally considered to be independent of the inductance with large inductance, it was found that dependence exists when small inductors are used. The capacitor voltage ripple was also derived. These theoretical findings have been verified using both simulations and experimental results.

A dual-layer receiver with a low aspect ratio and a low output fluctuation is proposed. It is composed of three parts: full-pitch coils, mixed-pitch coils and a flat receiver core. In EV dynamic wireless charging system, power supply rails with alternative arranged poles show a main drawback of sinusoidal output fluctuation when they are mated with conventional double D receiver coils. To solve this problem, a dual-layer receiver is proposed. Through the combination of full-pitch and mixed-pitch coils, the output fluctuation factor can be reduced from 100% to 29%. Compared with the conventional dual-DD receiver, the aspect ratio is reduced by 20% and the cross coupling between the receiver coils can be eliminated. The paper first analyzes the working principle, then explores the influences of the mixed-pitch coil's symmetry and vehicle chassis on the system, and the design principle of the proposed receiver is given afterwards. Finally, a 10-kW prototype with AC-DC efficiency of 93.2% was built for experimental verification. The experimental results were consistent with theoretical analysis and simulation results, thus proving that the proposed receiver could reduce the aspect ratio and achieve the decoupling between the receiver coils under the premise of reducing the output fluctuation.

For high-power, long-mileage dynamic wireless power transfer (DWPT) system, its economy and adaptability to complex working conditions are the main factors limiting its popularization and application. In this paper, the compensation and power supply of segmented rails are studied, and a DWPT system with mutual compensation of segmented power supply rails based on LCL topology is constructed. By multiplexing components, the number, cost and volume of devices are reduced, and the economy of the system is improved. The power supply topology is optimized to achieve constant-current characteristics over a wide load range to generate a stable high-frequency magnetic field in space and avoid short-circuit current induced by mutual coupling of adjacent rail. The resonant control conditions of the system are derived, and a phase shift control method based on the three-leg inverter is proposed to realize the full range regulation of transmitter current and output power, and improve the adaptability of the system. The characteristics of the proposed DWPT system have been verified by an experimental prototype.