This paper examines the performance of a 13kW high-power inductive power transfer system utilising a hybrid core structure with novel nanocrystalline ribbon cores and nanocrystalline flake ribbons. Conventional laminated nanocrystalline ribbon cores exhibit excessive edge losses due to high flux density concentrated on the edge and high eddy current losses in the lateral wall, potentially causing partial thermal runaway. To mitigate this issue, the solution is proposed to employ nanocrystalline flake ribbons as a shielding material on the edge while maintaining the nanocrystalline ribbon core as the main magnetic coupler. The performance of the hybrid core is evaluated under different power levels up to 13.8 kW. Experimental results reveal a nearly 2% increase in peak efficiency compared to the ferrite DMR44 and a 1% increase compared to standalone nanocrystalline ribbon cores, bringing the peak DC-DC efficiency to over 96%. Moreover, under 6.6 kW output power, the temperature rise after 2-hour operation is significantly reduced to a maximum temperature of 76.5°C with the proposed hybrid core, compared to 96.4°C with the ferrite shield and 110.6°C without any edge shield. The design highlights using nanocrystalline material in inductive power transfer systems to improve efficiency and thermal performance.

Dynamic wireless charging (DWC) technology can help alleviate the problem of short driving range for battery-powered vehicles. In this article, a model predictive control (MPC) is applied to the buck converter on the secondary side of a DWC system to address fast output fluctuations. This approach features a fast-dynamic response, and no communication link is required. To solve the key issue of MPC, which is the computational burden, a polynomial fitting method based on the parsing solution of the sampled-data model is proposed. The complex matrix exponential calculation is replaced by simple polynomial operations, and the optimal duty cycle can be calculated directly by solving a quadratic function. This significantly reduces the computational burden. A DWC experimental setup is constructed, and results show that the proposed MPC has a better dynamic performance compared to proportional-integral control. The adjustment time is only 140 μs (around seven switching cycles) when the reference voltage is stepping. Moreover, the computational burden for matrix calculation in two-step prediction can be reduced by 50.6% and 79.7% compared to the lookup table and Taylor series approximation, respectively. Meanwhile, MPC with current limitation is analyzed and demonstrates a neat spectrum, small ripple but large response time.

Nanocrystalline magnetic cores have been applied in inductive power transfer (IPT) systems as novel magnetic materials for their high saturation capability and flexible application. However, the loss of eddy current is still a primary concern in nanocrystalline material. This letter investigates two crushing patterns, namely square-crushing and dot-crushing, for nanocrystalline flake ribbon (NFR) to mitigate the eddy current loss in IPT applications. In the experiment, a 1 kW IPT prototype with a curved coupler for autonomous underwater vehicles (AUVs) is built to verify the loss performance. As a result, the coil with NFRs in the square-crushing pattern (S-pattern) has a higher quality factor than those with the NFRs in the dot-crushing pattern (D-pattern). Furthermore, the IPT system with S-pattern NFR exhibits an AC-AC transmission efficiency of 93.51%, possessing 0.89% higher than that of the D-pattern NFR case. The utilization of the S-pattern NFR offers multiple benefits, including minimizing core loss and facilitating the advancement of IPT systems with increased power density and enhanced installation flexibility.

Wireless power transfer (WPT) systems are widely applied in many scenes due to their safety, convenience, and flexibility. This letter proposes a novel control strategy named periodic energy control (PEC) in WPT systems. It is suitable for all kinds of compensation topologies of WPT systems. Specifically, it takes the energy input to the resonant network as the control target, which calculates the energy input by measuring the capacitor voltage or the inductor current, thereby controlling the switching action of the inverter. Meanwhile, it not only effectively suppresses the overvoltage (or overcurrent) when system parameters such as load and mutual inductance change, but also features low sensitivity to mutual inductance, which has advantages in the scene where mutual inductance changes. Moreover, this letter presents the principle of PEC and derives the energy input to the resonant network in various compensation topologies of WPT systems. Finally, experiments are presented to verify the effectiveness of this control method.

Wireless power transfer (WPT) is an emerging technology that enables efficient and convenient transmission of electrical energy wirelessly, and it has gained significant attention due to its potential to revolutionize various industrial, commercial, and consumer applications. This paper presents a study on the SS-compensated WPT system, focusing on characteristics analysis of periodic energy control (PEC) by the extended describing function (EDF) model. The model incorporates the influence of equivalent series resistors in the transmitting and receiving coils. The research highlights the feature of the PEC's input impedance angle always being greater than zero, which is attributed to the phase limitation of its driving circuit, making it suitable for zero voltage switching operations. Additionally, the study reveals that the operating frequency range of PEC is discontinuous and exhibits a piecewise monotonic property against frequency splitting. This research provides valuable insights for the accurate modeling and understanding of PEC behavior in SS-compensated WPT systems. Finally, simulations and experiments are conducted, the EDF model is verified with high accuracy, and the frequency skip is demonstrated. The dc-dc system efficiency is up to 95.3% for the WPT system using PEC.