Gallium nitride high electron mobility transistors have been considered as potential power semiconductor devices in modern power electronics owing to their high switching speed and low conduction loss, which facilitate efficient and compact solutions in high-frequency applications. However, their fast-switching behavior introduces challenges like voltage/current overshoot and parasitic sensitivity, necessitating accurate modeling for circuit optimization. This article proposes an associate discrete circuit (ADC) model for half-bridge leg inspired by the fixed-equivalent-admittance methodology in electromagnetic transient simulations. Unlike traditional piece-wise linear state-space models that require switching between different equation sets, the proposed ADC-based analytical model utilizes a unified framework to represent all transient submodes, thereby reducing modeling complexity and significantly improving computational efficiency. By incorporating layout parasitic parameters and nonlinear junction capacitances, the model accurately characterizes both switching transient and steady-state behaviors across various operating conditions. Simulation and experimental results validate the model's accuracy, speed, and scalability. The proposed modeling method can be extended to various devices and topologies, providing a practical framework for high-frequency power system design.

Configuring a battery energy storage system (BESS) is an effective approach to alleviating the peak shaving and valley filling burden on conventional thermal power units. However, excessive capacity increases investment cost, whereas insufficient capacity limits operational effectiveness. To address this trade-off, a multi-objective optimization framework is proposed to simultaneously maximize annual economic revenue and minimize load variance. The model comprehensively incorporates investment, operation and maintenance, decommissioning, environmental benefits, and deferred grid investment revenue, together with practical operational constraints on power limits, state of charge (SOC), charge/discharge states, and daily energy balance. A multi-objective particle swarm optimization (MOPSO) algorithm is employed to obtain the Pareto frontier, and the technique for order preference by similarity to ideal solution (TOPSIS) is applied to select the final optimal configuration. Simulation results based on a typical 24 h load profile indicate that the optimal BESS configuration is 27.7 MW/78.3 MWh, which reduces load variance by 32.15% and peak demand by 13.5%, while achieving an average annual revenue of 5.73 million CNY. Comparative analysis shows that the proposed method outperforms the traditional weighted-sum approach in both economic and technical indicators. Furthermore, the framework is extended to a WSCC nine-bus system with photovoltaic (PV) integration by introducing node voltage fluctuation as an additional objective. The results verify that the optimized BESS configuration can effectively mitigate voltage fluctuations under high PV penetration, demonstrating the scalability and applicability of the proposed method in renewable-energy integrated power systems.

Analysis modeling of isolated bidirectional DC-DC converters (IBDCs) is essential for effective performance analysis and design. To address the challenges posed by existing models in achieving accuracy, speed, and generality for optimization design purposes, this paper presents a novel generalized steady-state analysis model based on two-port network theory and frequencydomain analysis. The proposed model provides an analytical tool applicable to a range of IBDC topologies and modulation strategies, offering strong support in topology selection and automatic parameter optimization design. The effectiveness of this model has been verified through simulations and experiments, with the automatic parameter design software provided as an example to highlight its significant value and potential in IBDC design and applications.

The CLLC converter has been widely adopted in electric vehicle chargers due to its advantages of high efficiency, high power density, and low electromagnetic interference. However, in outdoor applications, such as fast-charging stations, harsh environmental conditions pose significant challenges to the CLLC converter, particularly in the form of short-circuit faults. To address this issue, a short-circuit-tolerant soft start control method for the CLLC resonant converter is proposed in this article. Based on time-domain model, the minimum limit of the switching frequency is adaptively adjusted according to the voltage gain, enabling limitation of the peak resonant current. Finally, experimental results obtained from a 1-kW prototype demonstrate that the proposed control method effectively limits the startup current under various load conditions and exhibits short-circuit tolerance during both startup and steady-state operation. The startup time is reduced by 20%-72% compared to existing methods with the same hardware configuration and maximum resonant current.

Wide voltage gain and load variations pose significant challenges to achieving high efficiency in series resonant dual active bridge (SR-DAB) converters, primarily due to increased circulating current losses and soft-switching failures, especially under light-load conditions. To overcome these limitations, this paper proposes a novel hybrid modulation strategy that seamlessly integrates triple-phase-shift (TPS) and variable-frequency (VF) control. A Thevenin equivalent model is developed to derive accurate ZVS boundaries by quantifying the combined effects of non-commutating-side voltage, parasitic nonlinearities, and switching transients. This facilitates a co-optimization approach: VF minimizes circulating current while TPS guarantees full soft-switching. Furthermore, a particle swarm optimization (PSO) algorithm is employed to efficiently identify the globally optimal operating points across the entire load range. Experimental validation on a 1-kW prototype demonstrates that the proposed strategy achieves a notable 1.5% efficiency improvement compared to conventional VF, effectively mitigating the efficiency degradation problem in wide-range operation.

Single-phase single-stage ac-dc converters are widely applied, especially in on-board chargers requiring high efficiency, high power density, and bidirectional operations. The full-bridge totem-pole dual-active-bridge topology offers promising prospects due to its compact integration and simplified control. However, conventional phase-shift modulation schemes fail to fully harness its potential and overlook the impact of initial inductor current coupling on grid current quality, control accuracy, and overall efficiency. This article proposes an optimized asymmetric extended phase-shift modulation scheme, which constrains the initial inductor current under traditional open-loop natural power factor correction requirements. The proposed scheme decouples initial inductor currents across adjacent switching cycles while minimizing peak-to-peak current through a multiobjective optimization approach. As a result, both converter efficiency and grid current quality are significantly improved. Experimental validation on an 800 W prototype confirms the effectiveness and feasibility of the proposed scheme. Under 350 V dc voltage and full-load condition, the proposed scheme notably enhances grid current performance and achieves peak efficiency improvements of 5.38%, 1.85%, and 0.78% in forward operation, and 5.57%, 1.89%, and 0.77% in reverse operation, compared to conventional SPS, EPS, and TPS schemes, respectively.

More-electric aircraft (MEA) power systems suffer frequent load transients and three-phase unbalance due to the growing variety and power rating of onboard electrified loads, yet the system's dynamic load tolerance limit has not been quantitatively clarified, threatening stable power supply. This paper targets this research gap by establishing a full model of the MEA variable-frequency AC (VFAC) power system and quantitatively analyzing its dynamic load adaptability. A hybrid GCU integrating hysteresis control and dual-loop PI regulation is developed for the three-stage VFAC generator, alongside high-fidelity models of typical aircraft electrified loads. Then, an integrated VFAC power system model is subsequently built in Simulink. Simulations are carried out under the worst-case 360 Hz low-frequency operating point to test system responses to load step changes and three-phase unbalance. The simulation outputs quantify the maximum permissible load step rates and characterize power quality degradation under unbalanced loading, offering quantitative guidelines for MEA load scheduling.

Full bridge LLC resonant converters have become the mainstream solution in the field of wide voltage range due to their advantages, such as soft switching, simple structure, and wide voltage gain capability. To improve the working efficiency of the full bridge LLC resonant converters with a wide input voltage range, a working modes based iteration (WMI) modeling method is proposed to obtain both dynamic and steady-state waveforms, which exhibits high accuracy and speed, laying the foundation for the parameter and hybrid modulation strategy design. Then, with the purpose of minimizing the effective resonant current, a resonant cavity parameter design process is proposed based on traversing parameters with the WMI modeling method, thus guiding the selection of circuit key components. Finally, a loss model of the converter is built, and a hybrid optimization modulation strategy is proposed by taking the minimum total loss as the optimization objective. The accuracy and speed of the proposed WMI modeling method are verified by comparing with the MATLAB/Simulink result. With the designed parameters and hybrid modulation strategy, a 97.0% peak efficiency and a 4.8% maximum efficiency improvement are reached on a 125-375 V-input and 48 V/240 W-output prototype.

The CLLC resonant converter operating in dc transformer (DCX) mode has excellent features, such as fixed switching frequency, load-independent voltage gain, full zero-voltage switching operation, and simple synchronous rectifier control, but the output voltage cannot be adjusted. To address this issue, this letter proposes a magnetically controlled CLLC-DCX converter based on variable resonant inductors. The proposed control method adjusts resonant inductors to change the equivalent transformer turns ratio n(e) while keeping the resonant frequency fixed. Finally, an experimental prototype is built to validate the proposed magnetic control method.

Cascaded DC systems are widely used in modern power system to interconnect the source converter with the load converter flexibly. However, the cascaded bus voltage would oscillate due to terminal impedance mismatch. The accuracy of oscillation frequency detection is a prerequisite for achieving adaptive active damping control successful. In this paper, an adaptive active damping method (AADM) utilizing the improved second-order generalized integrator-frequencylocked loop (ISOGI-FLL) to realize identification of resonant frequency and amplitude is proposed, which can achieve fast stabilization for the cascaded DC system with unknown or shifting parameters, and the effectiveness is validated by the experimental results.

The CLLC resonant converters are drawing more and more attention due to their superiority in high efficiency, high power density, and low electromagnetic interference. However, CLLC converter still suffers the problems of unsatisfactory voltage regulation and low efficiency under light-load conditions. To address this issue, a burst mode control method with dual active modulation for CLLC converter is proposed in this article. With the aid of time-domain model and offline particle swarm optimization (PSO) algorithm, the proposed method optimizes the switching sequences of the pulse packets to achieve the minimum current root mean square (RMS) with the same transmitted energy and requires only sampling of the input and output voltages. Comparative experiments were conducted on a 1-kW prototype and the results show that the light load efficiency can be improved by applying the proposed burst mode control. Peak efficiency of 97.4% is achieved at 10% rated load, which is an improvement of more than 2% compared to the previous burst mode approaches.

The dual-active-bridge (DAB)-based two-stage ac/dc converter is extensively applied in various scenarios, including electric vehicle chargers and solid-state transformers. In the two-stage ac/dc power converter, the dc-link voltage serves as the input voltage of the DAB converter and provides an additional control parameter affecting efficiency. Previous studies primarily focused either on variable dc-link voltage or on phase-shift degrees of freedom alone, neglecting the simultaneous use of both dc-link voltage and phase-shift for efficiency improvement. This article presents a current stress optimized strategy for the DAB converter with triple-phase-shift (TPS) and variable dc-link voltage control. First, the TPS modulation scheme and variable dc-link voltage range are introduced. Second, optimal dc-link voltage and phase-shift values are determined using analytical optimization algorithms. Based on these findings, a control scheme integrating the optimal variable dc-link voltage and phase-shift values is proposed. Furthermore, it is compared with conventional fixed dc-link voltage control to demonstrate improvements in zero-voltage switching range and peak current level. Finally, the effectiveness of the proposed strategy is verified through experiments on a two-stage ac/dc converter prototype, demonstrating its capability of significantly enhancing system efficiency across all power ranges.

The quasi-single-stage dc/dc converter employs an auxiliary converter to regulate the output voltage, enabling better adaptation to a wide input voltage range. However, conventional quasi-single-stage dc/dc converters exhibit significant power flow through the auxiliary converter under rated input voltage condition, limiting efficiency improvements and causing distortion in the resonant current. To address these issues, this article proposes a novel bipolar-assisted regulation quasi-single-stage dc/dc converter. First, the fundamental characteristics of the proposed converter, such as its operating mode, gain regulation, and power distribution, are analyzed. Second, a parameter design method is introduced to achieve zero voltage switching turn on for power switches. Building on this, a closed-loop control strategy is proposed to regulate the output voltage. Finally, the main circuit parameters derived from the optimized design are utilized, and an experimental prototype is developed and demonstrated to verify the effectiveness and advantages of the proposed converter, achieving an efficiency of 97.9% at rated input voltage and power.

Driven by the rapid global energy transition and smart grid advancement, solid-state transformers (SSTs) have become essential in modern power systems. Among SST components, the single-stage matrix (SSM) ac-dc converter is particularly attractive due to its simple structure, minimal component count, and ease of control. However, maintaining high efficiency with the SSM converter is challenging, primarily because of its wide input voltage range and the significant influence of half-bridge capacitors on the inductor current. To address these issues, this article proposes a novel three-degree-of-freedom (DOF) asymmetric modulation method based on traditional extended phase-shift modulation, introducing an additional DOF into the dc-side full-bridge structure. Through mode classification, comprehensive modeling, and optimization, an optimized modulation trajectory (OMT) was developed. The proposed OMT ensures that all power switches achieve zero-voltage switching operation while minimizing the root mean square of the inductor current and enabling real-time calculation. Finally, experimental validation demonstrates that the proposed OMT achieves up to 4.14% efficiency improvement compared to recent work, thereby confirming the method's effectiveness and accuracy.

The existing time domain models for CLLLC class resonant converters have at least one of the following drawbacks: 1) the model cannot be applied for different resonant tanks and circuit topologies; 2) the effect of parasitic capacitors and deadtime is ignored; 3) large computation time is required to obtain steady state waveforms. To address these issues, an advanced state-space based analysis (ASSA) model is proposed in this article. The operation stages by considering parasitic capacitors and deadtime are proposed and equivalent to a universal circuit, which largely increases the accuracy with low model complexity. Additionally, the ASSA model is universal for different inverter structures, rectifier structures, and different resonant tanks, including LC, LLC, CLL, CLLC, and CLLLC. To improve the calculation speed, a hybrid operation mode analysis and ASSA model is proposed to obtain closer initial values and achieve steady state 2.15 times faster than traditional state-space based analysis methods. Finally, experimental results of CLLLC, CLLC, and LLC resonant converters working in multiple conditions are presented to validate the effectiveness and accuracy of the proposed ASSA model. Compared with the traditional time domain model, the relative error of resonant inductor current waveforms is reduced from 5.91%-43.54% to 2.83%-19.42%.

With the increasing variety of electrified loads on aircraft, the aircraft power system is often affected by high-power load transients and three-phase load imbalances. However, the load transient boundary and the dynamic adaptability of the aircraft power system are still unclear, making it difficult to ensure its safe and stable operation. To address these issues, this paper establishes a variable-speed variable-frequency AC generation system model for a 115V/120 kW, 360-800 Hz aircraft power system, while analyzing the characteristic and developing models of typical electrified loads. A simulation model of the aircraft power system incorporating the generation system and various typical electrified loads is constructed with MATLAB/Simulink. Based on scenarios with the lowest generating frequency and high-performance control parameters, the impact of dynamic load variations on the bus voltage of the aircraft power system is analyzed, yielding the load transient adaptive range, and power quality data under three-phase load imbalance conditions. This study provides an accurate analytical method for aviation electrical power systems to adapt to high-power load transients and offers a basis for optimizing system behavior in response to three-phase unbalanced loads.

The CLLC converters are gradually becoming the most popular topology of isolated bidirectional dc-dc converters due to their high efficiency, high power density, and low electromagnetic interference. However, the commonly utilized pulse frequency modulation (PFM) faces efficiency degradation and unregulated output voltage at light loads. Phase-shift modulations such as extended phase shift and triple phase shift are often adopted to improve light-load efficiency, but their performance is not satisfactory when the voltage gain deviates from 1. To address this issue, a time-domain analysis model-based optimal variable frequency-TPS (VF-TPS) modulation scheme for the CLLC converter is proposed in this article. An offline particle swarm optimization algorithm is introduced to obtain the optimized combination of all four modulation variables for different operating conditions to ensure soft-switching and minimum RMS current. Finally, a 1 kW experimental platform was built, and comparative experiments were conducted. The results show that the proposed VF-TPS modulation scheme can improve efficiency across the entire power range, compared with PFM, the half-load and full-load efficiencies have been improved by 0.78% and 0.63% to 97.85% and 97.27%, respectively, at the minimum voltage gain.

Active power decoupling (APD) effectively addresses the issue of suppressing the dc voltage fluctuation in single-phase ac/dc converters. However, it usually uses the closed-loop decoupling capacitor voltage tracking control, which is complex due to the need for designing multiple parameters in the controller. This article proposes a closed-loop calculation control strategy for APD, demonstrated using a buck-type APD circuit. The method employs two resonant filters, with only one parameter to be set, significantly reducing the control complexity. In addition, a circuit parameter design method for achieving the minimum capacitance and zero voltage switching (ZVS) is proposed. This method takes the duty cycle limit into account. When the duty cycle is limited between 0.1 and 0.9, the capacitance is 0.775 times that of the ideal design method. Finally, a 1 kW single-phase totem pole power factor correction (PFC) prototype is constructed to validate results.

In order to improve the performance of inductor-inductor-capacitor (LLC) resonant converters in wide voltage range applications, many novel modulation strategies other than traditional pulse-frequency modulation (PFM) have been proposed, such as pulsewidth modulation (PWM) and phase shift modulation (PSM). However, the existing modeling method cannot be extended to other modulation methods easily. In most cases, the existing models are developed based on the assumption of ideal components, which neglect parasitic components and dead time effect. Practically, these nonideal factors have a significant influence on the steady-state operation and the soft-switching performance. Besides, due to the complexity and nonlinearity of the operation process, it is difficult to conduct the small-signal analysis. In this article, an accurate dynamic time-domain model is developed based on stage iteration, considering common parasitic components, the dead time effect, and various modulation methods. It can reflect the implementation of zero voltage switching (ZVS) and the high-frequency oscillation under the light load. Based on the improved dynamic model, a convenient and accurate small-signal analysis method is proposed. Simulation and experimental results are presented to verify the accuracy of the model. Compared to the traditional model, the relative error of the voltage gain can be reduced from 14.2% to 5.0%.

The quasi-single-stage dc/dc converter adjusts the output voltage through an auxiliary converter, better adapting to the needs of data center power supply units. However, existing quasi-single-stage dc/dc converters operate with high power flow through the auxiliary converter at rated input voltage, restricting efficiency improvement. To address these issues, this article proposes a novel quasi-single-stage dc/dc converter that achieves voltage regulation of the main converter via a bipolar auxiliary port, thereby reducing power flow through the auxiliary converter and improving efficiency at the rated input voltage. First, the basic characteristics of the proposed converter are analyzed, including working mode, gain adjustment, and power distribution characteristics. Second, a parameter design method is proposed to achieve ZVS turn on in all power switches. Based on this, a closed-loop control strategy for output voltage is proposed. Finally, based on the main circuit parameters obtained from the optimized design, a 320-450V input and 12V/500W output prototype is demonstrated, achieving a peak efficiency of 96.76%.