International Journal of Circuit Theory and Applications最新文献

Pulsed alternators exhibit multifunctional capabilities, including inertial energy storage, energy conversion, and pulse shaping, rendering them a crucial class of pulse power sources. The development of air-core and multiphase structures represents a prominent trend in pulsed alternator technology. This paper focuses on the investigation of an eight-phase air-core pulsed alternator, analyzing its electromagnetic characteristics and its ultimate current output capability. First, an analytical calculation model is established to determine the electromagnetic parameters. Subsequently, an in-depth discussion elucidates the analytical relationship between the pulsed alternator's ultimate output capability and its intrinsic parameters, clarifying the factors influencing the output current capability. Second, a three-dimensional field-circuit coupled finite element analysis model is constructed to analyze the magnetic field distribution characteristics and output characteristics of the pulsed alternator. Finally, a multiphase pulsed alternator experimental platform is constructed, and preliminary experimental research is conducted, laying a theoretical and experimental foundation for the optimization design and engineering application of pulsed alternators.

Conventional methods for the settling performance design of switched-capacitor integrators are only applicable under the assumption of an ideal feedback loop model of the embedded operational transconductance amplifiers, and the design results obtained are inaccurate. An approach for the accurate design of switched-capacitor integrators employing two-stage amplifiers is presented in this paper. The settling time expression is first derived based on an effective settling behavior model of integrators, and a design procedure aimed at a given settling time is then developed. The design accuracy is achieved by the error compensation for the analytical model estimated from the output of the SPICE simulation and the iteration of the design procedure. All error sources incurred by various parasitic effects in the circuit, including those of the switch transistors, can be considered, and design results are attained with SPICE-level precision. Simulated design examples of two switched-capacitor integrators are provided to verify the accuracy and effectiveness of the method.

To enhance the operation efficiency of single-phase full bridge inverter, a novel single-phase full bridge passive SiC-based soft-switching inverter topology is proposed. The passive auxiliary network (PAN) with low energy consumption is used to make the main switch achieve wide range pseudo zero-current switching (ZCS) switch-on and pseudo zero-voltage switching (ZVS) turn-off to implement economic power saving. The absence of auxiliary switches in the PAN can render the control of the system simpler. The distinguishing feature of this soft-switching inverter is that each bridge arm's switches share a resonant cell (comprising an absorption inductor and an absorption capacitor), significantly reducing the additional components attached to the main switches. It utilizes a large-capacity electrolytic capacitor to act as a constant voltage source, constructing a passive and lossless energy feedback loop. This enables the reset of the absorption components, thereby improving the efficiency of the inverter. During the dead-zone mode, the load current can continue to flow through the PAN, which can reduce the negative impact of the dead-time state on the output current waveform of the proposed inverter. The experimental results on a 3-kW prototype with rated output power show that the switching device can realize soft-switching, and the distortion rate of the output current waveform of the inverter is improved.

With the widespread application of wireless charging technology for electric vehicles, compatibility issues have arisen between charging devices of different brands, as well as misalignment during the charging process. Consequently, the interoperability and misalignment tolerance of various magnetic couplers have become significant challenges. This study proposes a wireless charging system based on a dual-decoupled spliced coil, designed to be interoperable with different coils (square coils, X-direction DD coils, Y-direction DD coils, and quadrupole coils) while maintaining a certain level of misalignment tolerance. The designed coil is capable of self-decoupling and is connected in series by two half-bridge rectifiers to produce a total equivalent mutual inductance equal to the sum of the absolute values of the two mutual inductances, thus improving the stability of the wireless charging system. Finally, to verify the interoperability and misalignment tolerance of the designed coils, a 1-kW experimental prototype was built. The experimental results and simulation analysis are relatively consistent, the designed coils can interoperate with four types of coils, the transmission efficiency is above 90%, and it has a certain misalignment tolerance.

Capacitive wireless power transfer shows promise for wireless energy delivery, utilizing capacitive coupling for transmission. Quantifying the coupling between individual transmitters and receivers is essential, as optimization techniques for optimal output impedance depend on accurate knowledge of the coupling coefficient. Because practical capacitive power transfer systems often experience variations in distance or alignment, impacting the coupling coefficient and consequently, the optimal output impedance, it is desired to constantly measure the coupling coefficient. However, existing methods for measuring mutual capacitance in CPT systems require specific conditions, making them unsuitable for live measurements. This paper introduces a method for live calculation of mutual capacitance in CPT systems, applicable during normal operation. We present a theoretical framework applicable to SIMO systems with an arbitrary number of receivers and validate our results experimentally for both SISO and SIMO systems using a 10-W prototype operating at a frequency of MHz. Our method shows strong agreement with established techniques, especially for systems with identical receivers. This approach enables live mutual capacitance calculation based on voltages and currents available during normal system operation. It is effective for SISO and SIMO configurations, confirmed by simulations and experiments.

To overcome the shortcomings of traditional online parameter monitoring sensor (OPMS) power supply methods, a wireless power transfer system with five-stage domino resonators is designed in this paper, which can obtain energy from the magnetic field around the high-voltage transmission lines (HVTLs) and continuously supply power to the OPMS within the maximum insulation distance of 2 m. Furthermore, innovative research was conducted on the impact of coil misalignment caused by external factors on Domino wireless power transfer system (DWPTS). Firstly, a general two port mathematical model and ideal simplified model is derived and based on this the relationship between system efficiency and mutual inductance value is analyzed when the mutual inductance between adjacent coils is the same. The efficiency, voltage gain, and input impedance angle changes under inductance offset are learned. Secondly, the phenomenon of frequency splitting is studied, and the system has multiple CV points at different frequencies. Based on the analyzed characteristics of the domino system, a coupler for DWPTS is proposed, and the influence of the total magnetic core width and arrangement number on the coupler is studied. Additionally, the characteristics of the coupler under radial and rotational misalignment, as well as its electromagnetic environment are analyzed in detail. A five-stage DWPTS experimental platform is established and alignment and misalignment experiments are conducted to verify the total energy transmission distance at 2, 1.5, and 1 m, respectively. A maximum power transmission of 110.4 W and 80.82% is achieved at a total transmission distance of 1 m. The experiment on misalignment shows that within a large range of misalignment, even in the worst case of coil misalignment, the efficiency can maintain over 80% of the alignment efficiency.

A hybrid structure bidirectional DC–DC converter (BDC) with a common ground, incorporating quadratic gain and switched-capacitor (SC) cells, is proposed in this article. The proposed converter consists of six power switches, five capacitors, and two inductors. It features a high-voltage conversion ratio, reduced voltage stress on power switches, and a common ground configuration, making it suitable for hybrid energy storage systems (HESSs). The voltage gain of the proposed topology can be further enhanced by extending the number of SC cells. A 300-W experimental prototype has been built to validate the theoretical analysis, achieving peak efficiencies of 95.85% in step-up mode and 95.24% in step-down mode.

In this paper, a speed–current single-loop control strategy for permanent magnet synchronous linear motors (PMSLMs) with load variations is investigated. First, a second-order model of the PMSLM is developed by combining the speed and q-axis current. Then, a speed regulation strategy consisting of a nonsingular terminal sliding mode control and second-order nonlinear disturbance observers is designed for the developed second-order model to improve the response and disturbance rejection performance of the PMSLM. The matched and mismatched disturbances of the second-order model are estimated by second-order nonlinear disturbance observers. The convergence of the studied control strategies is analyzed by the Lyapunov theory. Finally, the simulation and experimental results show the advantages of the studied control strategy in terms of response and robustness compared with the PID and SMC based on cascade structure.

This paper presents a two-port folded monopole antenna to be used as a signal combiner and radiating element in outphasing applications, enhancing the system efficiency by minimizing insertion loss. A simple but effective circuit model is proposed to estimate radiated and reflected power based on impedance values and the outphasing angle. The equivalent circuit was validated through analytical and experimental methods, using standard measurement techniques to obtain the $�Z$-parameters. Additionally, a custom setup utilizing a software-defined radio platform was implemented to overcome the limitations of conventional instruments in measuring outphasing systems and to verify the proposed model. Measurements performed on a prototype resonating at 933 MHz demonstrated excellent linearity and spectral performance, achieving an adjacent channel power ratio (ACPR) below −45 dBc, superior to other combining antennas in the literature. Additionally, a reasonable error vector magnitude (EVM) of −32 dB was observed for broadband signals modulated with QPSK, 16-QAM, and 64-QAM.

This paper presents a novel design method of quasi-optimal rat-race coupler with arbitrary port impedance. The arbitrariness of the port impedance is fully considered in the design of the rat-race coupler, which can avoid the additional configuration of matching network when connecting with other components. An integrated design equation for the rat-race coupler is derived using the even–odd mode method. Combined with the quasi-optimal theory, the dual-band, broadband, and compact design methods of arbitrary port impedance rat-race coupler are proposed, and the different characteristics can be achieved by only adjusting the parameters without any structure change. Three rat-race couplers are fabricated using double-sided parallel-strip line (DSPSL) for experimental verification, and the results are in great agreement with the theory.