For dual-output load applications, the conventional discontinuous pulsewidth modulation (DPWM) can introduce terminal voltage errors due to oscillated and unbalanced dc-link neutral-point (NP) voltages, which in turn increase low-order current harmonics. In addition, modified DPWM schemes using asymmetrical space-vector diagrams are computationally intensive. To achieve low-computational complexity and low-order harmonics mitigation, this article proposes a computationally efficient enhanced carrier-based DPWM (ECB-DPWM) scheme for Vienna rectifiers considering dc-link NP voltage impact. To reduce switching loss, the clamping modes considering dc-link NP voltage are analyzed in detail. The zero-sequence components (ZSCs) and modulation signals of ECB-DPWM are derived to minimize switching losses while addressing NP voltage. Experimental results verify that ECB-DPWM significantly reduces low-order current harmonics both under balanced and unbalanced dc loads, while lowering switching losses by over 36% compared with the optimized space-vector pulsewidth modulation (OSVPWM) and reducing runtime by 49% compared with the asymmetrical DPWM method.

With the rapid development of electric vehicles and renewable energy technologies, research on wide voltage gain techniques for bidirectional converters has attracted significant attention. This article addresses the technical bottleneck of limited voltage gain adjustment range in bidirectional CLLLC resonant converters, particularly the flat gain characteristics in the above-resonance operating region, by proposing a resonant converter control strategy based on hybrid bridge-arm structure. The inverter-side switching network can operate in three configurations: half-bridge (HB) structure, full-bridge (FB) structure, and full-half-bridge structures. Through effective coordination of these three configurations, the step-down capability of the resonant converter can be significantly enhanced while maintaining fixed switching frequency. The proposed strategy requires no additional components and effectively avoids the issue of wide-range sudden changes in switching frequency during FB/HB transitions encountered in conventional solutions. Furthermore, multiple parameters are introduced to derive the voltage gain and loss distribution of the proposed control method, with analysis conducted on its extensibility to other bridge-arm configurations. Finally, the feasibility of the proposed control method is experimentally verified using a 10 kW prototype.

Isolated bidirectional resonant converters play a key role in the field of electric vehicle charging and discharging. However, due to the presence of multiple magnetic components in the circuit, the improvement of power density is limited. In order to solve this problem, this paper proposes a magnetic integration scheme for high-power bidirectional CLLLC resonant converters, which is an energy-based leakage inductance evaluation strategy. An integrated magnetic (IM) component replaces the original multiple discrete magnetic (DM) components to improve the power density of the converter. Secondly, in order to meet the actual application scenarios, a design method for a highreliability CLLLC converter with an ultra-wide voltage range is proposed. Third, the rationality of the magnetic integration design is verified by finite element analysis software. Finally, the effectiveness of the proposed magnetic integration technology and design method is demonstrated through an experimental prototype with an input of 660V-860V, an output of 250V-500V, and a power of 30kW.

Phase-shifted full-bridge (PSFB) converters have become a mainstream isolated DC/DC topology due to their simple control, reliable structure, low switching stress, and excellent dynamic characteristics. However, in practical applications, PSFB converters face the challenge of parasitic oscillations. This paper analyzes the mechanism of rectifier diode oscillations in detail and proposes an effective suppression method. The proposed approach demonstrates strong oscillation suppression, simplicity in principle, and minimal impact on converter volume. Experimental results validate the effectiveness of the method.

Accurate wind power forecasting is critical for addressing grid instability caused by renewable energy intermittency. This study proposes a hybrid decomposition-optimization framework integrating signal processing and deep learning techniques. The methodology combines Complete Ensemble Empirical Mode Decomposition with Adaptive Noise and Variational Mode Decomposition for multiscale feature extraction, augmented by k-means clustering based on sample entropy for frequency-domain component identification. A sparrow search algorithm-optimized convolutional bidirectional long short-term memory network with attention mechanisms enables simultaneous spatial-temporal pattern recognition. Experimental validation using operational data from Inner Mongolia wind farms demonstrates significant performance improvements: R2 increased by 15.894%, with corresponding reductions in MSE (91.98%), RMSE (71.68%), MAE (71.15%), and MAPE (10.639%) compared to conventional models. The framework effectively resolves non-stationary signal processing challenges while maintaining computational efficiency, providing grid operators with actionable forecasting intervals for dispatch optimization. These advancements contribute to enhanced renewable energy integration and power system resilience.

Abstract To address the difficulty of fixed-parameter virtual synchronous generator (VSG) control in balancing frequency support, dynamic recovery, and steady-state power quality under varying operating conditions, this paper proposes a coordinated parameter optimization and smooth adaptive control strategy for VSG-based grid-connected converters. First, a small-signal active power–frequency model is established to analyze the effects of virtual inertia and damping on dynamic performance. Then, a six-dimensional dual-objective optimization model is formulated using the integral of time-weighted absolute frequency error and the total harmonic distortion (THD) of PCC voltage as optimization objectives. The model is solved using an improved multi-objective Pelican optimization algorithm, and the optimized parameter set is incorporated into an online adaptive law. By combining sigmoid-based smooth triggering with first-order tracking, continuous adjustment of virtual inertia and damping is achieved. Simulation results demonstrate that the proposed method effectively reduces power overshoot and maximum frequency deviation while maintaining a low three-phase average PCC voltage THD. In addition, additional non-optimized validation cases under low-SCR weak-grid operation and grid phase-jump disturbance verify the adaptability and operational stability of the optimized parameter set.

This article proposes a peak power control (PPC) strategy based on the LLC resonant converter to address the complex and dynamic power supply demands of artificial intelligence servers. PPC regulates the negative peak voltage of the resonant capacitor and the increment of the capacitor voltage set by the feedback loop. Specifically, it controls the charge quantity from the maximum power point of the resonant tank up to the moment when the switch turns off, thereby managing the power flowing into the resonant tank during the switch-on period. By linearizing the time-domain expressions of the circuit's state trajectories using a first-order Taylor expansion, a small-signal model of the proposed charge control strategy is derived. Frequency response analysis indicates that this control method exhibits favorable first-order characteristics, characterized by high bandwidth and high phase margin. To validate the effectiveness of this control strategy, a 24 V/240W LLC resonant converter prototype was constructed. The experimental results validate that the proposed charge control strategy ensures stable regulation of the output voltage and satisfies stringent transient response requirements.

In this paper, a bidirectional non-isolated AC-AC converter based on resonant switched capacitor principle is proposed. The new topology is described, analyzed, designed and tested in the laboratory. The characteristics of the converter at input voltage frequency and switching frequency are described in detail. The zero current switching of the power tube achieved by the resonant switching capacitor is the main advantage of the proposed circuit. The output voltage operating in the resonant state is half of the input voltage, and vice versa. The converter is designed for conversion between 220 V/110 V AC-AC voltage, and aims to replace traditional autotransformers in commercial and domestic applications. The experimental results verify the feasibility of the proposed topology and control method.

In this letter, a planar magnetically integrated inductor design method is proposed for a direct coupled three-phase interleaved Buck converter (three-phase IBC) with a three-pointed star (TPS) core geometry. Through a comparative analysis of various magnetic core structures, a TPS core featuring magnetic integration is selected, and the air gap positions are determined to effectively mitigate the eddy current loss on the PCB windings introduced by the fringing flux. Following this, the winding arrangement of the planar inductor is systematically analyzed, and an improved layout scheme is proposed, which significantly improves magnetic coupling and reduces inductor core losses. Finally, a 2 kW three-phase IBC prototype with a peak efficiency of 98.3% is built and tested. The results validate the effectiveness of the proposed design method and its theoretical analysis.

To meet the requirements of high voltage boosting and high efficiency, a novel high step-up zero voltage transition (ZVT) DC/DC converter based on active switched-inductor (ASL) is proposed. This converter combines ASL and coupled inductor structure, thus can reduce the voltage and current stress of power switch, and the active clamping technology provides zero voltage transition (ZVT) for all switches. The coupled inductors can realize relatively high voltage gain with appropriate turns ratio while all magnetic components can be integrated in one core. In addition, thanks to the leakage inductance, the reverse recovery problem of diodes is resolved. The working principle of the proposed converter is analyzed in detail, also the characteristics including voltage gain, the condition of ZVT is discussed. Then, a family of derived converters are listed and compared to each other. According to the proposed converter, a 500W prototype with 100kHz switching frequency is established in the lab, and the experimental results are given to verify the analysis.

With the growth of renewable energy, offshore wind power has become a key source for hydrogen production. However, in an islanded offshore wind-powered hydrogen production system without energy storage, fluctuations in wind speed can cause mismatches between wind turbine power and electrolyzer power requirements, leading to significant DC bus voltage variations and stability issues, especially due to the electrolyzer’s power change rate limitations. This paper proposes a solution to this problem. A power compensation control strategy for the electrolyzer is introduced, which dynamically adjusts its power output to absorb energy imbalances in the DC capacitor, stabilizing the DC bus voltage. Additionally, a power smoothing control method based on a second-order filter is proposed to adapt the wind turbine power to the electrolyzer’s power change rate limitations. This method smooths the wind turbine power and suppresses the DC bus voltage fluctuations. A rotor speed protector is also designed to ensure stable turbine operation; when the rotor speed drops below a threshold, the control switches from power smoothing control to maximum power point tracking (MPPT) control, preventing instability at low speeds. Simulation results using MATLAB/Simulink confirm that the proposed strategy effectively enhances the system’s stability.

During symmetrical voltage sags caused by grid faults, the inadequate active support capability of the conventional photovoltaic virtual synchronous generator (PV-VSG) may lead to system collapse or even grid disconnection. This paper examines the dynamic interaction between the photovoltaic array and virtual synchronous generator (VSG), proposing a variable step-size voltage tracking algorithm specifically designed for photovoltaic arrays. By predicting the maximum power output of the photovoltaic array and setting suitable load-shedding ratios, the suboptimal power point is calculated based on the power capacity of the grid-connected system. The inertia-induced oscillations of the system's active and reactive power curves during voltage sags are considered. An adaptive power angle control function is incorporated to address instability caused by increases in the power angle. A voltage feedforward compensation algorithm, based on the voltage sag ratio, is then employed to enhance the VSG's voltage support capability during voltage sags, enabling flexible responses to varying degrees of symmetrical voltage dips. Additionally, a dynamic impedance function is introduced to design virtual impedance, reducing system underdamping, minimizing oscillations, and buffering overcurrent surges during voltage dips or recoveries. Comparative stability analysis of the photovoltaic grid-connected system demonstrates a significant improvement in the active support capability of the PV-VSG during grid voltage sags.

Isolated bidirectional resonant converters play a crucial role in the domain of power electronics, particularly in the context of rapid charging and discharging applications for electric vehicles (EVs). However, in many instances, the demand for rapid charging results in increased charging current and larger converter volume, thereby reducing the efficiency and power density of the converters. This paper presents a novel analysis and design methodology of a converter employing sensorless synchronous rectification and applies a multi-segment linearization analysis method to resonant converters, which is simpler than time-domain analysis and more accurate than first harmonic approximation (FHA). This analysis provides a theoretical foundation for the implementation of synchronous rectification. It employs a hybrid control strategy of phase angle and frequency to regulate the switching on inverter and rectifier sides, significantly enhancing converter efficiency and broadening the gain range. A matrix transformer configuration is utilized to optimize thermal performance and enhance power density. Based on the proposed theory, the design of a 30 kW 660-860 V input to 250-500 V with 75 A max output prototype is discussed. The design outcomes indicate that employing synchronous rectification and matrix transformer with 10 PQ3548 cores, the converter can achieve a high power density of 8 kW/L (131 W/in) and peak efficiency of 98.4.

Grid-forming inverters are essential components linking renewable energy sources to the grid, and their stability is crucial for the reliable operation of the system. Grid-forming inverters based on traditional proportional-integral (PI) control demonstrate good small-signal stability in weak grids characterized by low short-circuit ratios (SCR). However, when connected to strong grids, it often leads to sub/super-synchronous oscillations, causing instability in the system. To enhance the grid-forming inverter's stability under strong grid conditions, this paper employing the linear active disturbance rejection control (LADRC) strategy in place of traditional dual PI voltage-current control loops. This study establishes positive and negative sequence impedance models of grid-forming inverters under traditional dual PI voltage-current control and LADRC voltage loop control using harmonic linearization methods. Based on the established sequence impedance models and Nyquist criterion, the paper identifies the reasons behind sub/supersynchronous oscillations induced by dual PI control under strong grid conditions. Stability comparisons are provided between dual PI control and LADRC control of grid-forming inverters under different grid strengths. The comparative results demonstrate that grid-connected inverters with LADRC exhibit superior adaptability to strong grids, demonstrating enhanced capability to suppress sub/super-synchronous oscillations. Simulation and experimental validations confirm the effectiveness of the LADRC control strategy.

Traditional wind turbine deloading relies on wind speed measurement, which is often inaccurate due to sensor limitations, affecting deloading precision. This study first addresses the challenge of reference power assignment in the constant-speed region by proposing an additional power control strategy based on adaptive reference power assignment via rotor speed feedback, eliminating power fluctuations and enhancing wind energy utilization. Secondly, a novel wind-speed-measurement-free deloading method is introduced: at low wind speeds, deloading is achieved by adjusting the optimal power coefficient; at medium and high wind speeds, a unique mapping between additional deloading power and pitch angle in the constant-speed region is established and fitted into a function using least squares. By measuring additional power and inputting it into the fitted curve, the corresponding pitch angle reference is obtained without wind speed measurement. In the power-limit region, smooth pitch angle transition is achieved, constraining power to a specified value. Grid-forming control with matching control is adopted to mitigate DC voltage fluctuations.

Bidirectional CLLLC converters have garnered significant attention due to their high efficiency, yet commonly face challenges including wide switching frequency and intricate parameter design. This article proposes a bilateral short-circuit fixed-frequency control (BSCFFC) method that employs asymmetric PWM (APWM) modulation and partial synchronous rectification (PSR) to achieve wide-range gain while substantially simplifying parameter design complexity due to fixed switching frequency. The transition processes between inverter- and rectifier-side H-bridge short-circuit operations are analyzed using trajectory transition method (TTM), corresponding to the buck and boost modes of the converter, respectively. A 10-kW experimental prototype validates the effectiveness of the proposed control strategy.

The modular multilevel converter(MMC)topology has been widely used in medium/high voltage high-power transmission and distribution and motor drive fields.The full-bridge submodule(FB-SM)MMC topology with fault handling capability is currently receiving increasing attention and application.However,in order to suppress the SM capacitor voltage ripple,the usage of SM capacitors with larger capacitance significantly increases the hardware cost and volume of the system.In this paper,a modified FB-SM with active power decoupling circuit(APD-SM)is introduced,it combines the ability of capacitor voltage ripple suppression and DC fault traversal through device reuse without changing the external output characteristics of the topology.Compared to traditional MMC,the SM capacitor voltage ripple of this topology can be suppressed significantly in the full power factor range.The deduction rules,operating principles,modulation methods,and control strategies of this topology are introduced in this artical.In addition,key parameters in the topology structure are designed and the topology is compared with traditional FB-SM topology from multiple aspects.Finally,the simulation and experimental platform of MMC with APD-SM and FB-SM(Abbreviated as APD-MMC and FB-MMC,respectively)are built,and experimental verification was conducted based on the prototype model.Simulations and experimental results verify the validity of the APD-MMC topology and control strategy.

The weak structure of most distribution lines in rural areas, coupled with the frequent occurrence of seasonal and hourly loads in rural life and production, can easily lead to the problem of low voltage at the end of the distribution network, which seriously affects the reliability of the power supply and the normal demand for electricity in the residence. Virtual synchronous generator (VSG) control based on distributed energy storage has both technical and economic superiority in low-voltage management, but there is a risk of equipment off-grid when the grid frequency deviation is large. Therefore, this paper proposes a voltage support optimization control strategy for rural distribution networks based on energy storage, which reduces the current and voltage drop of power supply lines in the form of “active+reactive” composite compensation and segmented compensation, and raises the terminal voltage to the grid-connected voltage range. As an emergency guarantee program for the reliability of the end of the station area, it can avoid the overload of the storage battery during operation, which leads to the disconnection of the storage converter, and shows stronger grid voltage support capability. Numerical calculations and simulation results verify the correctness and effectiveness of the voltage support optimization control strategy proposed in the paper.

High-proportion photovoltaic (PV) grid-connected systems are prone to frequency fluctuations and deterioration of power quality due to the randomness of output. Therefore, traditional PI control is difficult to cope with dynamic regulation requirements under complex working conditions. To improve the power quality of high-penetration PV grid-connected systems, this paper proposes a frequency modulation control strategy with PV and energy storage auxiliary based on a sliding mode controller. The strategy replaces the PI controller with an Integral sliding mode controller (ISMC), establishes a quantitative relationship between PV penetration and virtual synchronous generator (VSG) parameters, and enhances robustness. Furthermore, the strategy uses communication between PV clusters to generate a load shedding curve for the maximum power point (MPP) of PV, dynamically adjusting the load shedding rate. The PV array employs a variable step-size voltage control algorithm to adaptively track the load shedding rate curve. A storage adaptive distribution strategy is designed to store the load-shedding power in energy storage batteries, thus preventing resource waste caused by curtailing solar power. This control strategy can provide auxiliary frequency modulation services for virtual power plants under high PV penetration, improving the anti-interference capability of high-penetration PV grid-connected systems.

The distribution network in rural areas is weak, there are few reactive power compensation devices, the power supply radius is long, and the problem of low voltage is very prominent, which seriously affects the normal living standards of users at the end of the line. Compared with the traditional line transformation and reactive equipment compensation scheme, the grid-based comprehensive voltage management scheme based on distributed energy storage has the advantages of low cost, fast response speed and continuous compensation, but there are potential risks of overcharge and over-discharge of energy storage batteries during system operation. Therefore, this paper proposes a low-voltage collaborative governance strategy based on the orderly charging and discharging of distributed energy storage, which can effectively improve the terminal voltage of the line by flexibly adjusting the battery charging and discharging power and the line power compensation form, and can avoid the PCS disconnection caused by the overload of the energy storage battery during operation. Numerical calculations and simulation results verify the correctness and effectiveness of the proposed strategy, which is an innovative reliability emergency guarantee scheme for terminal voltage control in the rural areas.