Conventionally, the magnetic core in an inductive power transfer (IPT) system is spliced by pieces of ferrites, which is time-consuming and unable to realize a seamless fit on the curved surface. This letter proposes a compact curved coupler with a novel flexible nanocrystalline flake ribbon (NFR) magnetic core. Compared with ferrite core, the NFR not only enhances the application flexibility of the IPT system but also significantly reduces its weight in certain power. Based on the LCC -S compensation topology, a 1 kW IPT prototype for autonomous underwater vehicles is fabricated. The transmission characteristics and temperature performance of the system have been investigated under three power levels, considering various permeability values for NFR cores. Finally, the NFR with a permeability of 800 is chosen as the magnetic core, and the dc–dc system efficiency reaches 92.85%. Moreover, it is possible to restrict the maximum temperature to 54.1 °C, and the weight of the NFR cores accounts for merely 4.65% of the whole coupler.

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.

When autonomous underwater vehicles (AUVs) replenish energy through wireless power transfer (WPT) technology on the underwater charging platform, there are practical issues such as excessive transmission gaps and unstable positioning. Additionally, the fixed size of the charging platform leads to insufficient compatibility. This paper proposes a high compatibility WPT system based on a reconfigurable magnetic coupler (RMC) for AUVs replenishing underwater energy. The transmitter of the RMC is combined with the charging platform cage and can follow the charging platform cage in radial dimensions. RMC can provide better coupling performance, and its necessity and effectiveness have been verified through finite element simulation. When the proposed high-compatibility charging platform supplies energy to AUVs of different sizes, the RMC will reconfigure its structure, leading to changes in the transmitter's self-inductance. To address this issue, a switch-controlled capacitor (SCC) method was incorporated into the system to achieve dynamic tuning. Finally, an experimental prototype was built to test the functionality and performance of the proposed RMC structure and SCC method. Compared to existing methods, this approach significantly enhances the practical application capabilities of WPT technology in underwater charging platforms and positively contributes to the cluster deployment of AUVs.

This paper proposes the design and analysis of an inductive power transfer (IPT) system that features novel nanocrystalline flake ribbon (NFR) cores. The flake ribbons are produced by compressing the dielectric material with nanocrystalline ribbons, leading to a reduction in the eddy current loss. A complete magnetic core is then fabricated by laminating the ribbons, imparting anisotropic properties. The paper outlines the design methodology for NFR cores, considering this lamination characteristic in Double-D IPTs. Accordingly, NFR cores with a lamination factor of 0.375 and a core thickness of 3.2 mm have been designed, produced, and experimentally validated. The tests indicate an over 95% DC-DC efficiency and an over 96.3% AC-AC efficiency at the output power of 8.9 kW. To assess their thermal attributes, one-hour duration tests at continuous 6.6 kW operation were performed on NFR cores and ferrite groups. Results demonstrate that NFR cores maintain a cooler temperature at 76.4 °C, whereas the DMR44 and DMR95 reach 91.7 °C and 84.9 °C respectively. Additionally, the designed NFR cores have achieved 51% core weight reduction, 31% volume reduction, and 20% thickness reduction. The proposed NFR cores based on the design methodology can greatly enhance high power density IPT systems.

The classical Cuk, Sepic, and Zeta converters have found wide applications in various fields. However, there has been limited research exploring their relationships. This letter aims to uncover their relationships by focusing on their capacitor-less circuits (CLCs). Initially, it is observed that these three converters exhibit highly similar performance characteristics, such as equal voltage gains and average component currents. Subsequently, this letter establishes that their equivalent CLCs are the reason behind these similarities, presenting a new perspective on understanding dc-dc converters with capacitors. Furthermore, based on the above findings, a novel topology derivation method is proposed by connecting capacitors to a CLC. Compared with the traditional methods, the proposed method can derive families of converters with comparable performance. Moreover, the proposed method is particularly suitable to leverage existing converter designs and modify them to meet specific requirements. The proposed method successfully derives several groups of converters from different CLCs. For a group of converters derived from an equivalent CLC, their effectiveness and their performance relationship are verified experimentally.