This paper presents an improved generalized super-twisting control (IGSTC) scheme for neutral-point-clamped (NPC) converters subject to the line-inductance parameter uncertainties. By optimizing the algorithm structure, the proposed method accelerates transient response. An online fixed-time inductance estimation algorithm is integrated into the current-tracking loop, significantly enhancing the system’s robustness against inductance variations. Through Lyapunov-based analysis, the practical finite-time stability of the IGSTC and the practical fixed-time convergence of the identification algorithm are rigorously established. Finally, comprehensive simulations under both nominal and varying inductance scenarios validate that the superior performance of the proposed strategy.

In this paper, an inductive power transfer (IPT) system for distribution insulator based on reconfigurable autotransformer magnetic coupler (ATMC) is proposed. A three-stage IPT system architecture is proposed based on the form of a 35kV insulator structure. A novel multi-tap magnetic coupler in the form of autotransformer is proposed. The voltage conversion ratio and output characteristics of the IPT system can be reconstructed by changing the winding taps connected to the IPT system. An ATMC-based IPT system circuit model is established. The parameters of ATMC are optimized. The effect of system parameter reconstruction by changing the winding taps of ATMC is analyzed. An IPT system based on a reconfigurable ATMC with three winding taps on both the primary and secondary sides is designed, an experimental prototype is built.$3\times 3$sets of experiments are completed, and the solution to reconstruct the system state by changing the winding taps of ATMC is verified. The maximum efficiency of the system is close to 90%.

In this article, an underwater simultaneous wireless power and data transfer (SWPDT) system with 1-Mbps full-duplex communication link is proposed. The communication channel shares the coupler with the power channel without using additional communication coils. The transducers inject and extract high-frequency data carriers through the taps of the coupling coils to send and receive data. The proposed method for constructing a full-duplex communication channel no longer pursues the resonant relationship between inductance and capacitance. It takes advantage of the inherent characteristics of the higher-order circuit to simplify the circuit structure and maintain a high degree of design freedom. In addition, the center frequencies of the two communication channels do not shift with the change in the transmission distance, realizing the capability of misalignment tolerance. To improve the utilization efficiency of the communication frequency bands and achieve a high data rate, the system uses the minimum shift keying (MSK) modulation and coherent demodulation implemented by Xilinx Zynq-7000 FPGA. A 1-kW underwater SWPDT prototype with 1-Mbps full-duplex communication is presented to demonstrate the proposed system.

This article proposes a simultaneous wireless power and data transfer system with full-duplex multiple-input multiple-output (MIMO) communication channels for underwater applications. The system uses power coils to transfer information without additional antennas. Two independent communication channels are constructed, which form$2\times 2$MIMO communication channels. The data rate is doubled compared with the system with only a single communication channel. So a dedicated channel can be assigned from the two channels to transfer high-priority information, such as control signals and feedback signals, thereby improving communication reliability. Moreover, using two channels can also enhance communication speed. Data can be transferred in parallel on these two channels. To create two communication channels, transceivers load high-frequency carriers onto the coils using two taps for each power coil, resulting in a communication channel with a significantly high-order circuit. In addressing the challenge of designing high-order circuits, this article proposes the reduced-order model for the communication channel. Finally, a 1.1-kW prototype was built with two 1 Mbps full-duplex channels and a total transmission rate of 2 Mbps to verify the feasibility.

Dual active bridge (DAB) converters are applied widely due to the advantages of high efficiency, easy realization of soft switching and bidirectional isolation. For power converters, dead time effect is more and more difficult to be neglected because of the increasing switching frequency promoted by higher power density. However, most of the researches based on DAB converters focuses on optimal control strategies without considering dead time. Therefore, this paper gives a detailed analysis of DAB converters under EPS control with dead time consideration, and the intervals of inductor current zero point is used to distinguish conditions of each sub mode. Recessive-dead-time mode which is not affected by dead time is selected in this paper. Finally, the simulation results verify the correctness of the theoretical analysis.

As a power supply method with high spatial freedom, megahertz (MHz) wireless power transfer (WPT) has great potential in particular application fields. The role and importance of WPT are described from the perspective of interdisciplinary. This article starts with WPT systems’ performance at different frequencies, emphasizes the basic composition and working principle of MHz systems, and focuses on a comprehensive review of recent years on inverters, rectification, impedance compression, dynamic impedance matching, coupling structure design, and multiload model establishment. Meanwhile, different technologies are summarized, compared, and classified. Current challenges and future development trends are discussed.

In this paper, the fixed-time control problem of DC-DC buck converter systems with mismatched disturbances is investigated. Firstly, the sliding mode fixed-time observers are constructed to estimate the matched and mismatched disturbances of the systems. Secondly, a novel segmented terminal sliding mode control (TSMC) variable considering the mismatched disturbance of the system is designed based on the observations. To improve the tracking performance, a new second-order fixed-time reaching law is proposed. Then, in order to make the DC-DC buck converter systems with mismatched disturbances achieve accurate control in a fixed-time independent of the initial state, a novel fixed-time nonsingular TSMC based on the fixed-time observers is proposed. Finally, comparative experiments are conducted to verify the effectiveness and practicality of the proposed control strategy.

Efficient and simple modulation of output power is demanding for radio frequency plasma and wireless power transmission,magnetic resonance imaging systems. In this article, a power modulation strategy that can improve the linearity, power capability and efficiency simultaneously is proposed. The control modes ofon/offand Outphasing are combined to ensure shallow phase depth in a wide power range. Hybrid modules composed of load independent class Φ2structure and symmetrical class Φ2structures are adopted ason/offmodules and PS module to match the proposed control scheme, which are able to provide constant output voltage while remaining zero voltage switching (ZVS) state under resistive-inductive and resistive-capacitive load separately. Theon/offmodule is uniquely designed to behave as a static load when turned off. With the cooperation of control strategy and circuit architecture, the proposed system is able to regulate power linearly with optimal efficiency and minimal voltage and current stress. An implementation with four modules, 13.56 MHz, 25–200 W inverter system is demonstrated, the output power can be seamlessly and linearly controlled with efficiency always within 82%–93.5%. The heat dissipation in prototype is uniform, and is feasible to expand to a higher power compared with other control and circuit structures.

To solve the power supply problem of the high-voltage side detection module in HVDC applications, a multi-relay wireless power transfer (WPT) system with an operating frequency of 800 kHz is designed. This paper establishes the model of multi-relay WPT system and derives the expressions of the efficiency and output power. By analyzing the influence of the insulator metal flanges and optimizing the coil spacing, the energy transfer efficiency of the system can be improved. A 1.1m prototype with 8 resonant coils and 2 metal flanges is built and the experimental results verify the influence of metal flanges on the multi-relay WPT system and the feasibility of optimized arrangement of coils.

This paper presents a regulated 24V-to-1V series-capacitor buck converter to achieve single-stage high step-down dc-dc power conversions with high efficiency and high power density. Many of the challenges faced by conventional buck converters are overcome by this converter topology. The switching losses and noise of all switching elements in this topology are sufficiently reduced because the voltage stress of switches is reduced to one-fourth of the input source voltage at switching periods. By taking advantage of the benefits from the series-capacitor buck converter topologies, all switching elements of the converter allow for low withstand voltage MOSFETs with low drain-source on-state resistance and low gate charge total characteristics. Further, the use of coupled inductors can achieve a small steady-state current ripple and enhance transient response to the load steps. The effectiveness of the topology is verified by a 24V-1V/20A prototype with a peak efficiency of 91.6%.

The capability of misalignment tolerance is vital for an inductive power transfer (IPT) system. A new method that designs the parameters of series/series-parallel (S/SP) compensation topology with undiscovered strong misalignment-tolerant capability is proposed in this article. This article shows the possibility of keeping the output voltage basically constant even with high misalignment if the load is not too heavy and the parameters of the compensation circuit are properly designed. The relationship between primary input impedance angle and secondary input impedance angle with coupling coefficient and load resistance was also analyzed to achieve high efficiency over a wide load range. Then, a 60-W prototype with the performance of strong misalignment-tolerant capability was designed to verify the system performance, and it can be used for wireless charging of laptops or other desktop devices.

This article proposed a novel scheme integrating full-duplex communication into high-power wireless power transfer systems. The power and data are transferred through the same inductive link. A pair of coupling coils with taps are employed to omit the trap inductors that are widely employed in former simultaneous wireless power and data transfer (SWPDT) systems. The proposed scheme can reduce the system cost and size and improve the power transfer efficiency. The power and bidirectional data are transmitted using carriers of different frequencies. Frequency division multiplexing technique is utilized for full-duplex communication. The duplexer is carefully designed to separate the transmitted and received data signals. The circuit model of the system is built to analyze the power and data transfer performance. The crosstalk between the power and data transfer is also discussed. To improve the performance of data transfer, the method to determine the optimal coil tap position is proposed. A 300-W SWPDT prototype with a full-duplex data rate of 500 kb/s was built to demonstrate the feasibility of the proposed system.

Loosely coupled transformers (LCTs) play an important role in wireless power transfer (WPT) systems. The flat solenoid coupler and planar square coupler are two most commonly utilized LCTs. To compare the performance of these two structures, simulation using ANSYS Maxwell is conducted. For the sake of fairness, the length, width and height of the ferrite core, the length of the air gap, and the specification of the Litz wire are consistent. The coil turns is optimized to make the self-inductance of these two LCTs equal. Finally, the two optimized LCTs are comprehensively compared in terms of self-inductance variation, coupling coefficient, misalignment tolerance, leakage magnetic flux intensity, and cost.

In this paper, an isolated synchronous rectification DC-DC converter based on GaN HEMT is proposed, which can achieve soft-switching characteristics and reduce the conduction loss of the rectifier. In conventional rectifier converter, fast-recovery schottky diodes are used for resonant rectification, and the diode forward voltage drop results in larger diode conduction losses, which causes the power converter to be less efficient. To solve this problem, the proposed topology, whose rectifier diode is replaced by a synchronous switch, adopts synchronous rectification, which helps to improve the efficiency of power converters. Meanwhile, the transformers with magnetic core are also replaced by coreless planar transformers to reduce the volume. Thus, the system efficiency and power density can be improved. To achieve soft switching and reduce switching losses, the driving circuit of the rectifier circuit is optimized and the detailed design method of the proposed converter is analyzed. In tens of megahertz, the GaN HEMTs are adopted to reduce the driving loss, switching loss and conduction loss. A 20MHz prototype based on the proposed topology is designed in this paper. The experimental results verify the feasibility of the proposed converter and corresponding design method.

UV-lamp driver especially for radiation at 253.7nm plays an important role in sewage treatment. In this paper, characteristics of the excitation of mercury atoms in the lamp are investigated deeply based on both theoretical knowledge on collision and experimental results on relationship between the irradiance at 253.7nm with the lamp power. An optimization design scheme is proposed to prolong the life span of the UV-lamp and enhance the irradiation of 253.7nm. The irradiance in each waveband emitted by the lamp is measured by illuminometers to validate the accuracy of the proposed optimization scheme. Experimental results verify the soundness of the theoretical analyses.

The parameters of the resistance model are obtained through various experiments under different lamp power in this study. Polynomial fitting curves are obtained for these parameters to get the values under some certain lamp power. Then simulations in PSIM are conducted by using the calculated values to verify the reliability and accuracy of the method adopted. Good agreement is obtained between the experimental results and simulation results. Finally, In order to improve the lifetime of the lamp and increase the UV irradiance at 253.7nm, the double capacitor topology is proposed and studied.

Compensation is a vital part in Inductively Coupled Power Transfer (ICPT) to achieve higher efficiency, power density and reliability. This article proposes two unilateral LC compensation topologies for ICPT system after thorough theoretical analysis, which achieve both zero-voltage switching and constant voltage output characteristics over a wide range of load. A 300W phase-shifted full bridge DC-DC Wireless Power Transfer device is designed and built which achieves an efficiency of 87.8% using proposed structure.