A full-freedom wireless power transfer for spheroid joints is proposed to solve the problem of power transmission between the caput-articularis and the acetabulum in a spheroid joint. According to the characteristics of the spheroid joint, a hemispherical coil and a spherical coil are designed having no effect on the performance of the joint. Hemispherical and spherical magnetic cores are used to optimize the magnetic field distribution of the transmitter and receiver coils to reduce the electromagnetic influence on the external environment of the acetabulum and the internal environment of the caput-articularis during the power transmission process. Practical results obtained from a hardware prototype are included. They confirm that the maximum transmission efficiency of the designed system is 91%, and the transmission efficiency is always higher than 80% when the caput-articularis rotates freely. INDEX TERMS Spheroid joints, full-freedom, hemispherical coils, spherical coil, wireless power transfer (WPT).

Frequency modulation (FM) has been widely used in the inductor-inductor-capacitor (LLC) resonant converter due to excellent soft switching features. However, low power efficiency in light load conditions and complex control due to the nonlinear converter behaviour are common concerns for the FM method. In this study, a hybrid mode-hopping modulation method is proposed for the LLC resonant converter to address these challenges. The LLC resonant converter operates at any two of three power-efficient operating modes for a different amount of time within a single modulation period. By determining the mode hopping time and combining different mode-hopping modulations, the LLC resonant converter can achieve a wide range of output power and maintain high efficiency at the same time. Besides, since the switching frequencies are fixed, the relationships between the duty cycle and the output power are linear, which can significantly simplify the control design. Compared with the existing modulation methods, the proposed hybrid mode-hopping modulation makes the LLC resonant converter behaves linear, simplifies the control design, achieves wide operation range and ensures high efficiency even in light load condition.

A universal and robust wireless power transfer (WPT) system crossing insulators to feed monitoring terminals on power towers of overhead transmission lines is presented in this study. Analyses of the WPT system crossing high-voltage insulators string indicate that system characteristics and energy loss vary under different insulation conditions. Transfer characteristics of the WPT system with different relative positions between the coils and insulators are analysed to find an insensitive scheme. To achieve a non-interacting and relatively efficient operation under the scenarios, magnetic shielding layers are designed to further isolate the WPT system and insulators. Moreover, the resonant frequency point tracking method of this specific WPT system is studied and implemented to achieve robust transfer efficiency. Experimental results prove the feasibility, and the system displays a robust transfer performance with various high-voltage insulators. Such energy feeding system can be used in disc or composite insulation towers universally with simplified installation methods.

Quantum technology provides a ground-breaking methodology to tackle challenging computational issues in power systems. It is especially promising for Distributed Energy Resources (DERs) dominant systems that have been widely developed to promote energy sustainability. In those systems, knowing the maximum sections of power and data delivery is essential for monitoring, operation, and control. However, high computational effort is required. By leveraging quantum resources, Quantum Approximate Optimization Algorithm (QAOA) provides a means to search for these sections efficiently. However, QAOA performance relies heavily on critical parameters, especially for weighted graphs. Here we present a data-driven QAOA, which transfers quasi-optimal parameters between weighted graphs based on the normalized graph density. We verify the strategy with 39,774 expectation value calculations. Without parameter optimization, our data-driven QAOA is comparable with the Goemans-Williamson algorithm. This work advances QAOA and pilots its practical application to power systems in noisy intermediate-scale quantum devices.

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