Search Results (61)

The modular multi-active bridge (MMAB) converter—characterized by electrical isolation, modular design, high power density, and high efficiency—can be readily scaled to multiple DC ports through an internal shared high-frequency bus (HFB), establishing it as a viable topology for DC transformer (DCT) applications. However, its interconnection to a DC grid via low-damping inductors may provoke low-frequency oscillations and instability. To mitigate this issue, this paper employs a pole-zero cancellation approach to model the conventional constant-power control (CPC) loop as a second-order system, thereby elucidating the relationship between equivalent line impedance and stability. An active damping control strategy based on virtual impedance is then introduced, supported by systematic design guidelines for the damping compensation stage. Simulation and experimental results confirm that under weak damping conditions, the proposed method raises the damping coefficient to 0.707 and effectively suppresses low-frequency oscillations—all without altering physical line impedance, introducing additional power losses or requiring extra sensing devices—thereby markedly improving grid-connected stability. Full article

A novel wavelength-selective absorber is numerically designed and analyzed using a three-dimensional finite-difference time-domain method. The proposed solar thermal absorber consists of an array of asymmetric tungsten ring nanowires deposited on a tungsten thin film. This structure achieves high solar absorption efficiency (78.5%) and low thermal emissivity (5%) at 100 °C, resulting in a photothermal conversion efficiency of 73.55% under standard solar illumination. The selective absorption arises from the excitation of magnetic polaritons and surface plasmon polaritons. To further elucidate the physical mechanisms behind the spectral response, an equivalent inductor–capacitor circuit model is employed. The absorber also exhibits polarization-insensitive and angle-independent performance up to 50° for both transverse magnetic and transverse electric polarizations. These results demonstrate the potential of the proposed metamaterial absorber for advanced applications in solar energy harvesting, photothermal conversion, and thermal emission. Full article

With the development of distributed electric propulsion aircraft, researching airborne high-efficiency, high-power-density, high-gain, high-dynamic and low-ripple, low-stress DC-DC that meets aviation standards is an urgent and profoundly challenging task (Research Background). We propose a new topology to implement related applications. The new topology consists of an interleaved switched-inductor unit for a high-gain, low-ripple, and high-dynamic response, and a switched-capacitor unit for secondary boosting and low voltage stress. This study first analyzes in depth the operating principle and electrical characteristics of the proposed topology in different modes, showing that the proposed topology can achieve an extremely high voltage gain while maintaining low voltage stress. Moreover, the proposed topology employs interleaved inverse coupled inductors to eliminate right-half-plane zero (RHPZ). We establish a universal design guideline for coupled inductors by deriving the equivalent inductance equations, and we implement an ultra-lightweight switched-coupled inductor using planar thin-film integrated magnetic technology. We conduct small-signal modeling to verify the loop characteristics and stability of the proposed converter. Finally, the correctness of the theoretical analysis and the advantages of the proposed converter were verified through a 5000 W experimental prototype and comprehensive comparative experiments. Full article

Multiphase buck converters are critical in data centers and base stations, where their efficiency and thermal performance dictate system reliability. Conventional current-sharing methods fail to equalize power losses under component mismatches, causing localized overheating and efficiency degradation. This paper introduces a dynamic current balancing strategy based on active power loss sharing. A coupled current–temperature–resistance model is developed to dynamically estimate the equivalent resistance of each phase, capturing the behavior of MOSFETs, inductors, and PCB traces. This model enables real-time, loss-based current weight adjustment to actively balance interphase losses. Experimental results demonstrate that the proposed approach improves peak efficiency by up to 3–8.6% and reduces the critical component temperature rise by 11.6 °C under typical loads, confirming its substantial value in enhancing the performance of multiphase power systems. Full article

This paper simplifies indirect resonant switched-capacitor (ReSC) converters using the state-space average model method. The operation principles of the 4:1 and 5:1 ReSC converters derived from the Dickson (4:1) circuit are analyzed, and the corresponding state-space average matrices are derived based on their equivalent circuits. The resonant inductor of the specific resonant branch is eliminated by analyzing the composition of the state-variable matrix, thereby obtaining the simplified topologies of 4:1 and 5:1 indirect ReSC converters. The simplified topologies are simulated and experimentally verified. The results prove the correctness of the state-space average modeling method and the effectiveness of the simplified topologies. Full article

Current ringing in dual-active bridge (DAB) converters significantly degrades efficiency and reliability, particularly due to resonant interactions in the magnetic tank impedance network. We propose a novel impedance resonant channel shaping technique to suppress the ringing by systematically modifying the converter’s equivalent impedance model. The method begins with establishing a high-fidelity network representation of the magnetic tank, incorporating transformer parasitics, external inductors, and distributed capacitances, where secondary-side components are referred to the primary via the turns ratio squared. Critical damping is achieved through a rank-one modification of the coupling denominator, which is analytically normalized to a second-order form with explicit expressions for resonant frequency and damping ratio. The optimal series–RC damping network parameters are derived as functions of leakage inductance and winding capacitance, enabling precise control over the effective damping factor while accounting for core loss effects. Furthermore, the integrated network with the damping network dynamically shapes the impedance response, thereby attenuating ringing currents without compromising converter dynamics. Experimental validation confirms that the proposed approach reduces peak ringing amplitude by over 60% compared to the conventional snubber-based methods, while maintaining full soft-switching capability. Full article

Inductor parameter variations often affect the control performance of digital current mode (CM)-controlled buck converters as their high performance relies on accurate converter modeling. However, recent studies have shown that reliably monitoring inductance with current sensors and high-frequency sampling greatly increases the overall cost of this process. To address this issue, an online inductance monitoring method without a current sensor is proposed in this study. First, an inductance calculation model is derived by applying the dynamic characteristics of a buck converter with inductor volt-second and capacitor charge balance principles. The model’s accuracy is guaranteed by considering inductor current switching ripple characteristics. Nevertheless, output capacitor equivalent series resistance (ESR) can degrade the accuracy of the proposed calculation model. Thus, to enhance the tolerance of the inductance calculation model to capacitor ESR, the ESR effect on inductance monitoring is investigated. With the proposed capacitor ESR estimation method, inductance monitoring achieves reliable accuracy, even for a buck converter with high capacitor ESR. The effectiveness of the proposed method is verified by simulations and experiments on a buck converter with digital sensorless current mode (SCM) control. Full article

The high switching speed of SiC MOSFETs can induce resonance between parasitic inductors and capacitors, owing to rapid changes in current and voltage, leading to excessive crosstalk parasitic oscillation. This can increase SiC MOSFETs’ gate oxide voltage stress, reducing their service life and even directly leading to gate overvoltage failure. However, there is still a lack of investigations of active control of gate driving in systematic converters because crosstalk parasitic oscillation, indicated by high frequencies in MHz, is challenging to control in a power converter with gate voltage stability and high switching speed. This paper investigates an active gate drive based on negative feedback to fully drive SiC MOSFETs with high efficiency and stable gate voltage to exploit the advantages of high dv/dt over 20 V/ns in SiC MOSFETs and further realize the miniaturization of power conversion systems. It first investigates a dynamic model of SiC MOSFET gate-interfered oscillation in parallel application derived from a circuit with equivalent junction capacitance in power devices. Then, the operating principle of the Negative Feedback Active Gate Drive (NFAGD) application strategy for parallel SiC MOSFETs is demonstrated. Finally, the experiment verifies the proposed strategy’s effectiveness in suppressing crosstalk parasitic oscillation in parallel SiC MOSFETs, and an 8 kW synchronous buck converter prototype is built to verify the NFAGD’s performance in systematic converter applications. Full article

Wireless power transfer (WPT) is recognized as a critical technology to advance carbon neutrality in transportation by alleviating charging challenges for electric vehicles and accelerating their adoption to replace fossil fuel. To ensure durability under traffic loads and harsh environments while avoiding vehicle obstructions, WPT primary circuits should be embedded within pavement structures rather than surface-mounted. This study systematically investigated the optimization of magnetite-modified asphalt material composition and thickness for enhancing electromagnetic coupling in WPT systems through integrated numerical and experimental approaches. A 3D finite element model (FEM) and a WPT platform with primary-side inductor–capacitor–capacitor (LCC) and secondary-side series (S) compensation were developed to assess the electromagnetic performance of magnetite content ranging from 0 to 25% and pavement thickness ranging from 30 to 70 mm. Results indicate that magnetite incorporation increased efficiency from 80.3 to 84.7% and coupling coefficients from 0.236 to 0.242, with power loss increasing by only 0.25 W. This enhancement is driven by improved equivalent permeability, which directly enhances magnetic coupling efficiency. A critical pavement thickness of 50 mm was identified, beyond which the reduction in transmission efficiency increased significantly due to magnetic flux dispersion. Additionally, the nonlinear increase in power loss is partially attributed to the significant rise in hysteresis and eddy current losses at elevated magnetite content levels. The proposed design framework, which focuses on 10% magnetite content and a total pavement thickness of 50 mm, achieves an optimal energy transfer efficiency. This approach contributes to sustainable infrastructure development for wireless charging applications. Full article

Half-bridge converter series microgrid (HBCS-MG) is susceptible to a variety of uncertainties and disturbances during operation, and therefore, the use of the traditional integer-order models cannot accurately reflect the effects of environmental variations on internal components of the off-grid system, such as converters, filters, and loads, including factors like time delays, memory effects, and multi-scale coupling. The fractional-order control method is better equipped to deal with these disturbances, thereby enhancing the robustness and stability of the system. In the off-grid state, a fractional-order PI (FOPI) controller is employed for double-closed-loop control, and the load voltage feedforward control is utilized to offset the impact of load voltage fluctuations on the system. A new simplified equivalent circuit calculation method for the fractional-order inductor is proposed, and a complete fractional mathematical model of the system in the dq rotating coordinate system is established to obtain the transfer function between the load voltage and the input voltage. Furthermore, the impact of the fractional-order variation of the FOPI controllers and the fractional elements on system performance in the frequency domain and time domain is described in detail. The simulation results are compared with the theoretical analysis to demonstrate the accuracy of the mathematical model. The overshoot of the load voltage at the switching instant of 0.7 s is reduced by 4.2% compared with the integer-order PI controller, which proves that the fractional-order controller can improve the system control accuracy. Full article

With the continuous improvement of battery energy density and converter power density, as well as the miniaturization and lightweighting of related airborne electrical equipment, all-electric aircraft with hybrid power supply systems provide more trade-off space and possibilities for the design of future aircraft. It is indispensable to search for a more valuable topology and apply it to airborne power supply. This paper proposes an airborne high-gain unidirectional DC-DC converter suitable for between low-voltage unit and high-voltage bus, which consists of interleaved magnetic integrated switched coupled inductor units and improved switch capacitor units. This paper first analyzes the steady-state operating characteristics under different modes; the new topology has higher voltage gain and lower stress. Secondly, in response to the challenges of high efficiency and high power density, we propose a magnetic integration design method and comprehensive experimental scheme based on the EIE-type magnetic core structure. This successfully integrates multiple discrete inductors into a single magnetic core. Furthermore, based on the comprehensive consideration of steady-state, transient performance and power density, the general design criteria for a high-gain switched coupled inductor are summarized through the equivalent mathematical model of reverse flux coupling. Additionally, by adjusting the coupling coefficient, the converter can achieve zero-voltage switching under light load conditions, demonstrating versatility and scalability and better meeting the application requirements of electric aircraft. The proposed prototype can provide voltage gain in the range of 12–22 times the input voltage gain by varying the input voltage from a 12–24 V fuel cell. The comprehensive performance of the converter, including steady-state, transient, and efficiency, was tested under D < 0.5 and D > 0.5. The experimental results show that the proposed converter possesses advantages such as high gain and low stress, a high dynamic response and low ripple, and high efficiency and high power density, which can provide a more advantageous DC-DC converter solution for airborne hybrid power supply systems. Full article

The application of induction heating power supply in the continuous production line of tinplate has garnered significant research and scholarly attention. However, the impedance matching of LC or CLC resonant circuits in the system lacks flexibility and is susceptible to overvoltage during startup. As a solution to the problem, a novel four-order LCLC parallel resonant circuit was proposed in this study for high-frequency induction heating power supply. By incorporating auxiliary inductors in parallel with CLC compensating capacitor branches, the induction heating system can operate reliably and achieve optimal load impedance matching. The equivalent circuit and mathematical model of the new resonant load were established, and the frequency characteristics of the circuit system were analyzed. Then, the parallel resonance characteristics of the new resonant circuit were comprehensively elucidated, including the quality factor, impedance characteristics, behavior of resonant current, and properties of voltage regulation. Finally, a simulation model of a high-frequency induction heating power supply was developed based on the proposed LCLC resonant circuit and compared with LC and CLC resonant circuits. The results demonstrated that the induction heating power supply system utilizing the proposed LCLC parallel resonant load exhibits superior parallel resonant characteristics, enhanced load impedance-matching flexibility, and improved output voltage stability when compared to traditional LC or CLC parallel resonant loads. Full article

This article presents a buck converter in which the inductor has been replaced by a transmission line. This approach would be practically conceivable if the power supply and load had a greater spatial distance. Alternatively, the model derived in this way could also be regarded as an intermediate model in order to replace a power coil via discretization with a larger number of smaller coils and capacitors. In the time domain, this new converter can be described by a system of coupled partial and ordinary differential equations. In the frequency domain, a transcendental transfer function is obtained. For comparison with an equivalently parameterized conventional converter, Padé approximants are derived. A linear controller is designed for the converter topology under consideration. Full article

This study presents the electrical modeling and characteristic analyses of energy storage systems (ESSs) based on the internal impedance characteristics of batteries to improve ESS stability. Frequencies ranging from 1 kHz to 0.1 Hz were injected into lithium-ion batteries, and the variation of the internal impedance of the batteries was obtained based on the reflected wave to determine the ESS state of charge (SoC) and temperature. The changes in the basic electrochemical impedance spectroscopy characteristics of the ESSs were observed. Specifically, the voltage, temperature, and SoC of an ESS that could be employed as a renewable ESS were analyzed. The impedance characteristics of the ESS were investigated via experimentation and simulation. The ESS comprised an electrically equivalent circuit of a series inductor ($L_S$), series resistor ($R_S$), parallel resistor ($R_P$), and parallel capacitor ($C_P$), as well as a MATLAB program based on its transfer function to generate energy. Furthermore, a method was developed for analyzing the frequency response of ESSs. The feasibility of the proposed electrical modeling was examined for a 58.4 V, 75 Ah, 4.4 kWh ESS. Full article

To solve the problem of system output voltage fluctuation caused by interferences such as load fluctuation and internal inductor parameter perturbation in a flyback converter, a second-order linear active disturbance rejection control (LADRC) strategy based on output voltage is proposed in this paper. A small-signal model of a CCM flyback converter is established, and the equivalent transfer function of voltage control based on second-order LADRC is derived. A second-order LADRC is constructed, and a parameter design method for the controller is proposed. The response characteristics of the output voltage of the converter under five internal and external disturbances of different control strategies are compared and studied using MATLAB R2022b/Simulink simulation software, and a CCM flyback converter experimental platform based on dSPACE is built to verify the corresponding comparative experiments. The simulation and experimental results jointly verify the superiority of the control strategy for the anti-interference and robustness of the output voltage of the CCM flyback converter. Full article