To overcome traditional limitations in handling complex disturbances, a novel fractional-order second-order sliding mode control (FOSOSMC) is developed for a class of nonlinear systems in the presence of matched and mismatched uncertainties, ensuring the properties of stability and dynamic performance. The main novelties are highlighted as follows. Firstly, a structurally flexible continuous SOSMC manifold incorporating FO calculus is constructed by taking into account the design of a family of sliding variables, which ensures that the state trajectory can converge to the equilibrium point accurately in a finite time and address the chattering problem owing to its memory and hereditary properties, while uniformly compensating for mismatched uncertainties. Furthermore, the straightforward sliding manifold structure allows for diverse designs of control laws. For simple single-input single-output systems, their fast convergence and high precision under lumped uncertainties can be guaranteed by combining the FOSOSM manifold and a fast-terminal sliding mode-type reaching law. For complex multi-input multi-output systems, a state-dependent adaptive gain is fitted to the FOSOSM manifold to obtain stronger robustness without sacrificing control accuracy or complicating parameter tuning. The global finite-time stability of the closed-loop dynamics is demonstrated by means of Lyapunov functions. Finally, simulation and experimental results verify the excellent control performance of the proposed method for nonlinear systems with uncertainties.

To address potential issues such as current surges, frequency transients, and voltage fluctuations during transitions between grid-connected and islanded operations in microgrids, this paper proposes a hybrid control strategy integrating PI control combined with sliding mode control and integral controller. This strategy synchronizes the amplitude through PI control and the phase through a hybrid control method combining sliding mode control and integral control. It improves synchronization speed while addressing the chattering issue in sliding mode control. Additionally, a fixed-rate transition method is adopted to ensure smooth switching from grid-connected to islanded mode. Simulations conducted in Plecs validate the effectiveness of the proposed control strategy in achieving seamless mode transitions.

Aiming to improve the performance of general buck converters in complex disturbance environments, an adaptive integral-type non-singular terminal sliding mode (AINTSM) control method with zero-crossing control gain is proposed in this paper. In contrast to conventional linear sliding mode (LSM) and NTSM methods with fixed gain, the proposed AINTSM approach maintains a simple structure while effectively mitigating chattering due to the adaptive gain and overcoming singularity issues associated with global convergence. Initially, an accurate model is developed incorporating bounded matched and mismatched disturbances; Subsequently, an AINTSM controller is designed by integrating an integral error regulation with an adaptive zero-crossing gain, and global finite-time convergence is achieved by Lyapunov-based analysis; Furthermore, the impact of variations in control parameters on the system's dynamic and static performance is analyzed, with stability conditions for the AINTSM parameters clarified by phase trajectory analysis. Finally, numerical simulations and experimental findings under parameter disturbances verify the efficacy of the proposed method.

This paper proposes an improved YOLOv5 deep learning algorithm to efficiently detect foreign objects in wireless power transmission (WPT) systems based on infrared images, in response to the presence or dropping of metallic foreign objects in wireless charging systems. First, the model is made lighter and the detection speed is improved by replacing the backbone network CSPDarkNet53 with MobileNetv3. At the same time, the ECA attention mechanism is added to make the network pay more attention to the parameter relationship information and localization information of the model, improving the feature extraction capability of the network. Secondly, the original loss function CIoU of the network is replaced with WIoU, which makes the model converge better and improves the precision of the algorithm detection. Finally, the improved YOLOv5 model was validated on the collected infrared image datasets for the detection of metallic foreign objects, with an increase in precision from 96.2% to 98.3%, recall from 96.5% to 98.8%, overall mAP to 99.5%, and the detection speed improved by nearly 15%, successfully enabling the detection of foreign objects in wireless power transmission systems via infrared images.

In the paper a position constraint algorithm is proposed to achieve high power density, based on the thermal resistance model of a half-bridge LLC system under natural convection. An LLC system with resonant frequency of 1MHz, input voltage of 290-330V, output voltage of 48V and power of 1kW is designed by using the third generation of power semiconductor device GaN. The electrical characteristics of the circuit are verified by simulation software. The loss of the system and the heat dissipation path of the LLC system with planar winding are analyzed, and the thermal resistance model of the system is established. Based on the thermal resistance model of the system, the heat dissipation power of each device is reduced, and the simplified thermal resistance model of each device is established. The device position constraint algorithm is established in a complex system without integration and differentiation. The simulation results show that in the LLC system under the position constraint algorithm, each device operates within the required temperature range, the error between the simulated value and the calculated value is within 5%, and the power density reaches 8.23W/cm3.

In this paper, a foreign object detection (FOD) system based on thermal infrared imaging is designed, taking advantage of its benefits, such as strong penetration in extreme weather conditions, high accuracy of non-contact detection, and no side effect on the wireless power transfer (WPT) system. Firstly, theoretical analysis and improvements are made on image processing techniques such as bilinear interpolation, Gaussian filtering, Operational Test Support Unit (Ostu) adaptive binarization, and morphological operations. Next, the processing advantages of the enhanced algorithms are confirmed using the openCV toolbox. Then, the aforementioned image processing techniques are implemented using embedded programming via the STM32 microprocessor, and the system’s foreign object detection capability is also verified by designing experiments for the location and type of foreign object under 5kW power level. Finally, the experimental results show that the WPT foreign object detection system is effective in the case of detecting and locating foreign objects that up to the size of a half yuan coin even an M4 nut, when the sensor is 15 cm away from the foreign object and the maximum viewing angle is within 110°. At this point, the minimum required temperature deviation between foreign object and background is 7°C, as well as the detection processing time is less than 0.5s, which fully satifies the demand for foreign obiect detection in the WPT system.

Dynamic magnetic coupling resonate wireless power transfer (WPT) system with single magnetic pole track allows very limited lateral migration of the power receiver relative to the power supply rail. The multi-pole rail improves the issue of lateral migration effectively, but when the receiver moves along the rail, the null points make it difficult to be applied to the equipment which carries none energy storage component. This paper presents a new multiphase receiver cooperating with multipolar power supply rail, which can improve the power transferring stability. Enabling applications such as automatic guided vehicles, robots, electrical vehicles which require continuous power supply, and ensure them to work continuously without any energy storage component. Besides, the improvement is achieved with any kind of shape of bipolar or multipolar tracks.

In this paper, a novel dynamic wireless power transfer system is designed for roadway EV powering application. Multiple LCL resonators are parallel connected in a high-power inverter and are turned on/off through vehicle positioning result. Compared to the conventional long-rail manner, firstly, the miniaturized transmitter can greatly reduce the electromagnetic radiation. Secondly, construction costs are significantly reduced due to both the transmitter and receiver do not require ferrite. Finally, the generalized state-space averaging and small signal model are built to analyze both the steady-state and transient response process. Experimental results validate the proposed dynamic model and system performance.