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30 September 2025, Volume 23 Issue 5
  

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    DC-DC Converters
  • Optimization Strategy of Power Return and Loss for Series Resonant DAB Converter
    LI Ning, YANG Jialin, TIAN Bowen, LI Jie, ZHANG Yan
    2025, 23(5): 1-9. https://doi.org/10.13234/j.issn.2095-2805.2025.5.1
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A series resonant DAB converter (SRDAB) is taken as the research object in this paper, and an efficiency optimization strategy for reducing the power return is proposed to improve the converter's operation efficiency under the phase shift modulation strategy. First, a mathematical model of the transmission efficiency of SRDAB is established under phase shift modulation, the mathematical expression for power return during its operation is derived, and the parameters that affect the power return are obtained. Second, the mathematical expressions for the transient and on-state losses generated during the operation of the converter are formulated, a mathematical model for its operation efficiency is constructed, and the relationship of its efficiency with the phase shift ratio and the ratio of switching frequency to resonant frequency is obtained, thus optimizing the two key parameters to further improve the operation efficiency. Finally, the correctness and effectiveness of the proposed efficiency optimization strategy were verified by performing simulations and building experimental circuits.
  • Stability Analysis for Digital Multi-phase DC-DC Converter
    ZHU Jian, HU Yaohua, LI Xuening
    2025, 23(5): 10-17. https://doi.org/10.13234/j.issn.2095-2805.2025.5.10
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    With the rapid development of microprocessors, more and more attention is paid to the advantages of digital control of microprocessor power supplies as the output capacitor and its equivalent series resistance (ESR) are gradually reduced, and sufficient stability is required for these digital multi-phase Buck controllers. Digital constant on-time multi-phase controllers are studied. First, the stability conditions of the system are derived through a digital compensation ramp (i.e., a ramp with a fixed slope in one switching cycle), the total inductor current information and the charge changes at both ends of the output capacitor. Then, the requirements for the slope are obtained using the stability conditions, where the effects of analog-to-digital converter (ADC) sampling delay and circuit propagation delay are considered. Conclusions can be drawn by classifying and analyzing the overlapped and non-overlapped duty cycles. Based on SIMPLIS simulations and by designing and changing the minimum compensation slope and the actual slope parameters, it is found that the simulation results are consistent with the theoretical analysis results, showing the accuracy of stability analysis for the digital multi-phase Buck converter.
  • Optimal Control of Backflow Power of Dual Active Bridge DC-DC Converter Based on EPS
    CUI Fengxin, SHI Anbang, YU Shan
    2025, 23(5): 18-24. https://doi.org/10.13234/j.issn.2095-2805.2025.5.18
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    A multi-objective optimal control method based on extended phase shift (EPS) is proposed for a dual active bridge (DAB) converter in order to simultaneously reduce the backflow power and improve its dynamic performance. First, the output power and backflow power characteristics of EPS in each mode are comprehensively analyzed, mathematical models are developed, and the optimal combination of the backflow power shift angles is solved according to the Karush-Kuhn-Tucker (KKT) condition. Second, a virtual voltage compensation scheme is used to improve the dynamic performance of the system by rapidly changing the transmission power at that moment. Finally, the proposed scheme was compared with the traditional single phase shift and EPS schemes through experiments, thereby verifying its effectiveness and advantage.
  • Reduced-state Double Integral Sliding-mode Control for Watkins-Johnson Converter under Resistive-inductive Loads
    HUANG Chao, LIU Shengdao, LI Zhixin, HE Baowei
    2025, 23(5): 25-33. https://doi.org/10.13234/j.issn.2095-2805.2025.5.25
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    A double integral sliding-mode (DISM) controller is introduced into the control strategy for a four-switch Watkins-Johnson (WJ) converter, which can improve the stability of the converter under bipolar voltage output and wide resistive-inductive load conditions. However, the direct application of its controller has a problem that the state variables cannot be measured unless two current sensors and one voltage sensor are used. Aimed at this problem, a nonlinear resistance is used to approximately replace the output load impedance of the converter, a large-signal reduced-order model suitable for the control of a sliding-mode variable structure is established, and an improved reduced-state DISM controller is designed accordingly. The improved controller utilizes the matching of sliding-mode coefficients to eliminate the influence of equivalent nonlinear resistance, thus avoiding the problem that the state variables cannot be directly measured unless a large number of voltage and current sensors are used. Simulation and experimental results show that the reduced-state DISM controller only needs to use one voltage sensor to make the converter work stably under the condition of bipolar voltage output and wide resistive-inductive loads, and the dynamic response performance of its output is less affected by changes in the operating point, indicating a strong control performance.
    • DC-AC Inverters
  • Research on Passivity-based Control Strategy for Load Resonant Soft-switching Grid-connected Inverter
    ZHANG Yajing, ZHANG Huanchen, WANG Mian, LI Jianguo, MA Shuang, WANG Jiuhe
    2025, 23(5): 34-41. https://doi.org/10.13234/j.issn.2095-2805.2025.5.34
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Load resonance soft-switching can effectively reduce the switching loss of single-phase grid-connected inverters, which is a research hotspot in high-frequency inverter applications. However, the traditional PI control strategy based on linear models is easy to be unstable under large signal disturbance, and the system output waveform is poor. Since the passivity-based control strategy based on the nonlinear theory can effectively improve the output and stability of the system, a passivity-based control strategy for a load resonant soft-switching inverter based on an Euler-Lagrange model is proposed. A single-phase full-bridge grid-connected inverter in unipolar BCM (boundary conduction mode) modulation mode is modeled in detail, and a passivity-based controller based on the damping injection method is designed. To verify the effectiveness of the proposed control strategy, a simulation model of the resonant soft-switching inverter is built, and this strategy is compared with the traditional PI control strategy under steady-state and transient conditions.
  • Novel Power Equalization Modulation Strategy for Cascaded H-bridge Inverter
    GU Jun, ZHANG Weiguo, LI Ping, ZHANG Ming, DU Zhibin
    2025, 23(5): 42-50. https://doi.org/10.13234/j.issn.2095-2805.2025.5.42
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    Under the traditional phase disposition (PD) modulation strategy, there is a power imbalance problem among the units in a cascaded H-bridge inverter. Aimed at this problem, the control principle of freedom degrees is analyzed, and a novel power equalization modulation strategy is proposed. On the basis of ensuring the output power equalization and voltage harmonic characteristics, the power equalization time is shortened, and the complexity in digital control is reduced. On the one hand, the freedom degrees of triangular carriers are recombined based on the PD modulation method to distribute them evenly in different carrier layers. Then, by fully utilizing the switching redundancy state at each output level, the power equalization is achieved within a carrier cycle to shorten the time needed for achieving the equalization. On the other hand, the complexity in digital control is reduced by restructuring the vertical freedom degree of the modulated wave. Finally, the theoretical analysis and feasibility were verified by simulation and experimental results.
  • Control Strategy for Leakage Current Suppression in Non-isolated Grid-connected Photovoltaic Inverter
    GAO Fengyang, YANG Kaiwen, SONG Zhixiang, GAO Xuanyu, GAO Jianning
    2025, 23(5): 51-60. https://doi.org/10.13234/j.issn.2095-2805.2025.5.51
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In a grid-connected system of non-isolated photovoltaic (PV) inverters, the electromagnetic interference causes the problem of leakage current. Aimed at this problem, an improved model predictive control strategy is proposed for a three-level inverter. First, a mathematical model of the grid-connected inverter system is established to analyze the generation mechanism of leakage current and its relationship with the common-mode voltage. Second, the common-mode voltage variation rate is controlled to improve the model predictive direct power control algorithm, thereby optimizing the optimization result to achieve the suppression of leakage current. Finally, the conventional strategy and the proposed improved model predictive control strategy are compared and analyzed through simulations in terms of output power, harmonic distortion of grid-connected current, DC-side neutral point potential balance and leakage current amplitude. Results show that the proposed strategy performs well in all the above four aspects, and its leakage current suppression effect can reach 99.5% compared with the conventional model predictive control strategy.
  • Low-leakage Current HERIC Transformerless Single-phase Photovoltaic Grid-connected Inverter
    CHEN Caixue, LIU Zongyuan, ZHANG Lucheng
    2025, 23(5): 61-68. https://doi.org/10.13234/j.issn.2095-2805.2025.5.61
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    To solve the problem of large leakage current in a photovoltaic (PV) grid-connected inverter, a low-leakage current HERIC transformerless single-phase PV grid-connected inverter topology is proposed. This inverter topology only needs eight power switching tubes, four of which constitute four quasi-bidirectional voltage switching units. The four quasi-bidirectional voltage switching units are divided into two groups, and they alternate conduction with grid frequency to realize continuous current, thus reducing the loss of switching tubes and effectively suppressing the common-mode leakage current. Finally, the proposed topology was verified by simulation and experimental results.
  • Method for Suppressing Second-order Harmonic Current of Grid-connected Inverter
    ZHU Jingjing, CHEN Min, REN Sheng, LI Hongyang
    2025, 23(5): 69-78. https://doi.org/10.13234/j.issn.2095-2805.2025.5.69
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    Harmonic pollution is one of the key problems restricting the grid connection of new energy sources. There are many factors that lead to an increase in current harmonics of grid-connected inverters, including the harmonic voltage of the grid and the sampling error of voltage and current signals in the grid-connected inverter system. On the basis, the principle of voltage sampling error and current sampling error of the grid-connected inverter system affecting the 2nd-order harmonic current of the inverter is analyzed, and a 2nd-order harmonic current suppression method based on high-precision harmonic sampling and 2nd-order harmonic current three-phase double-frequency rotation dq feedback is studied. In addition, a model of the 2nd-order harmonic current suppression loop is established, a design method for the parameters of the 2nd-order harmonic current suppression loop is given, and the expression of suppression effect is deduced. Finally, the proposed method was verified by experimental results of a 100 kW prototype.
  • Improved Model Predictive Control Strategy with Fixed Switching Frequency Based on NPC Three-level Inverter
    WANG Zhaohui, FENG Ling, YANG Shunfeng, LI Zhe, HU Liang
    2025, 23(5): 79-87. https://doi.org/10.13234/j.issn.2095-2805.2025.5.79
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    To reduce the calculation amount in the model predictive current control (MPCC) algorithm for a three-level inverter model, eliminate the weighting factor, achieve a fixed switching frequency and improve the steady-state performance of the system, a three-vector fixed frequency MPCC algorithm based on vector set selection is proposed. First, through the analysis of the relationship between current and voltage, the control of current under the rotational coordinate system is converted into the control of voltage under the stationary coordinate system by using the beat-free idea, and the candidate vector set is selected according to the sector where the reference voltage is located, thus reducing the calculation amount. Second, to achieve the midpoint potential control, according to the different effects of different switching vectors of a neutral point clamped (NPC) three-level inverter on the neutral point and the principle of switching smoothness, different candidate vector sets are reasonably selected, and the switching vector action time is obtained by using the principle of volt-second balance. Afterwards, the optimal switching sequence is selected according to the evaluation function. Finally, the traditional MPCC and the proposed algorithm are compared, and experimental results show that the proposed algorithm has advantages such as small calculation amount, fixed switching frequency and low current harmonic content.
  • Analysis of Novel Series-connected Hybrid-leg MMC
    ZHANG Xi, YAO Jiang, ZHONG Qihao, LIU Guobing
    2025, 23(5): 88-95. https://doi.org/10.13234/j.issn.2095-2805.2025.5.88
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    In a high-voltage flexible DC power transmission system, the modular multilevel converter (MMC) has unique advantages. Compared with those of the ordinary MMC, the output voltage levels of a hybrid-leg MMC (HL-MMC) consisting of submodules (SMs) and IGBT are doubled, the harmonic content of output voltage is reduced, and the DC bus voltage utilization is also doubled under the condition of the same number of SMs. The series-connected HL-MMC (SC-HL-MMC) is composed of three single-phase HL-MMCs, and its number of SMs is reduced by 2/3 under the condition of the same DC bus voltage. To be equipped with a DC short-circuit fault-tolerant capability, a hybrid SC-HL-MMC consisting of half bridge SMs (HBSMs) and full bridge SMs (FBSMs) is applied, and the scheme of optimal ratio between FBSMs and HBSMs is analyzed to satisfy the short-circuit fault ride-through requirement. To verify the performance of the proposed topology, a simulation model is built. Simulation results show that the stable three-phase output voltage from the SC-HL-MMC contains less harmonic under the rated operation condition, and it can block the short-circuit current rapidly under the DC short-circuit fault condition, thereby verify the validity of this topology.
    • Modeling and Control
  • Research on MPPT Control Strategy Based on Improved PSO Algorithm Using Chaotic Mapping and Gaussian Perturbation
    XIAO Yiping, ZHAO Yunfeng
    2025, 23(5): 96-104. https://doi.org/10.13234/j.issn.2095-2805.2025.5.96
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    Under the partial shade condition of photovoltaic (PV) arrays, multiple peaks will appear on the P-U curve, and the traditional particle swarm optimization (PSO) algorithm cannot search for the maximum power point quickly and accurately. In view of this issue, a maximum power point tracking (MPPT) control strategy based on improved PSO algorithm using chaotic mapping and Gaussian perturbation is put forward. First, a chaotic Sine mapping was introduced to construct a nonlinear random incremental inertia weight, and Gaussian perturbation was introduced in the “individual cognition” part of the particle swarm. Meanwhile, a logarithmic function was used to construct a learning factor, thus forming an improved PSO algorithm based on chaotic mapping and Gaussian perturbation. Through the test of six typical unimodal and multimodal functions, it was verified that this algorithm converged faster and was less susceptible to local maxima. Then, the algorithm was applied to MPPT control, and comparative simulations of different algorithms on MPPT control were performed. The comparative simulation results show that in three cases of uniform light intensity, static partial shading and dynamic shading, the MPPT control strategy based on improved PSO algorithm using chaotic mapping and Gaussian perturbation has a faster convergence speed and a smaller search oscillation amplitude, and it can find the maximum power point with a higher searching precision, thereby improving the power generation efficiency of the MPPT system.
  • Research on Photovoltaic MPPT Control under Shading Conditions Based on Jaya Algorithm
    GUO Weixin, ZHANG Zhidong
    2025, 23(5): 105-111. https://doi.org/10.13234/j.issn.2095-2805.2025.5.105
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    Aimed at the issue that the implementation of maximum power point tracking (MPPT) using group heuristic algorithms for photovoltaic arrays under shading conditions depends on algorithm-specific parameter settings, which leads to problems such as difficulty in the design of algorithms, a low tracking efficiency and large tracking errors, the tracking control of MPPT under shading conditions is implemented based on the Jaya algorithm. The proposed algorithm requires only general control parameters without any specific control parameters, and the solution of maximum power always moves towards the best solution during iterations. In addition, the worst solution is discarded to avoid local solutions, so that the system always tracks the maximum power accurately and maintains efficient operation. A simulation model of photovoltaic arrays under shading conditions is built in MATLAB/Simulink, and the Jaya algorithm is compared with traditional PSO and GA algorithms under the same model. Experimental results show that during the process of optimization, the use of the Jaya algorithm can track the maximum power in the shortest time while keeping the smallest tracking error and oscillation. At the same time, the global maximum power point can also be re-located accurately and quickly when the light intensity changes abruptly.
  • Design and Distributed Control of DG Converter with Cyber-attack Defense Capability
    WEI Yongjun, QIN Qiumi
    2025, 23(5): 112-120. https://doi.org/10.13234/j.issn.2095-2805.2025.5.112
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    To reduce the dependence of a control system on the communication network, a DC microgrid (DC-MG) usually adopts the distributed control architecture. However, due to the lack of global information, this control mode is highly vulnerable to cyber-attacks, which leads to greater security risks in the DC-MG. There are many types of cyber-attacks, among which the false data injection attacks (FDIA) account for the highest proportion and pose the biggest danger. On this basis, aimed at the instability problems such as interruption of DC-MG operation caused by FDIA, a DC-MG cyber-attack detection and control method based on feedforward neural network (FNN) is proposed. First, the influence mechanism of FDIA causing the instability of the control system is studied, and a mathematical model of instability caused by FDIA is established. Second, an intelligent estimator is constructed by using FNN to monitor the output current from a distributed power converter in the DC-MG, and the error data values of FDIA are calculated according to the output from the estimator. Third,aimed at the calculated values of error data, a reference tracking method based on a PI controller is introduced to reduce the error data in the attacked converter. In addition, the proposed method can eliminate all the high-domain unba-lanced attacks.Finally, the proposed method was simulated and verified by experiments carried out in MATLAB/Simulink and OPALRT,respectively, and results proved its effectiveness.
    • Renewable Energy System
  • Research on Lightning Receiving Characteristics of Photovoltaic Module with Fouling Surface and Corresponding Influencing Factors
    ZHOU Qibin, DENG Yin, BIAN Xiaoyan, ZHANG Yao
    2025, 23(5): 121-129. https://doi.org/10.13234/j.issn.2095-2805.2025.5.121
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    As a kind of clean, pollution-free and renewable energy, photovoltaic ( PV ) power has been vigorously developed and utilized worldwide. However, PV power generation systems are likely to suffer from lightning strikes due to long-term exposure to open areas. Since the existing researches on the lightning receiving of PV modules are all based on the condition that the module surfaces are free of fouling, they do not consider the effect of fouling surface on the lightning receiving characteristics. Aimed at the deficiency in the existing researches on the lightning receiving characteristics of PV modules with fouling surface, a simplified fouling model of PV module suitable for lightning strike is established. Then, through the simulation calculation of electric field intensity and charge density of the PV module with and without fouling, it is found that compared with those of the module without fouling, the electric field intensities at the head and end of the fouled side of the PV module increase by 41.1% and 33.8%, respectively. Meanwhile, a lightning strike rod-plate model of PV module with fouling surface was built in a high-voltage laboratory to carry out long-gap discharge tests, and it was found that the PV modules with fouling surface were more susceptible to lightning strike, thus verifying the accuracy of the simulation model. Moreover, the influence of the installation angle of PV modules on the lightning receiving characteristics in the case of fouling surface was also discussed. Results show that at any angle, the lightning strike probability and electric field intensity of the fouled side were higher than those of the unfouled side. Compared with that in the case of an installation angle of 8°, the electric field intensity at the end of the fouled side decreased by 24.8% when the installation angle was 45°, indicating a deceased probability of lightning strike.
  • Study on Temperature Field Evolution in Hydrogen Fuel Cell Diffusion Layer
    GAO Qingzhen, PAN Daoyuan, HUANG Shengzhou, WANG Yiyan
    2025, 23(5): 130-140. https://doi.org/10.13234/j.issn.2095-2805.2025.5.130
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    To study the temperature evolution law in the hydrogen fuel cell diffusion layer and analyze the factors affecting the temperature distribution, the cathode and anode diffusion layers and their internal fluid were taken as the research objects, and a correlation method for the heat and mass transfer between diffusion layer Z-Y profile and X-Y profile was established. Considering the fluid Soret effect, Dufour effect, adsorption effect and fluid-solid conjugate heat transfer effect in the diffusion layer, and combined with the N-S equation, Brinkman-Darcy extended model,Langmuir adsorption equation and interfacial capture Cahn-Hilliard theory, a heat and mass double-diffusion model of gas-liquid two-phase flow in porous media was constructed.The Lattice Boltzmann method was used for numerical solution to demonstrate the temperature evolution law in the diffusion layer and elucidate the mechanism of fluid state influence on the temperature distribution. Results show that the diffusion layer’s thermal conductivity is closely related to its internal fluid state. The thermal conductivity of hydrogen-water vapor atomized flow in the anode diffusion layer is better than that of the separated flow composed of air-liquid water in the cathode diffusion layer. Therefore, the anode diffusion layer has obvious advantages over the cathode diffusion layer in terms of the equilibrium of temperature field evolution, continuity of isotherm distribution and utilization of heat transfer area. The research results can provide a theoretical basis for improving the thermal management level of hydrogen fuel cells.
  • Review of Key Technologies for Fault Ride Through of DFIG-based Wind Turbine
    LING Yu
    2025, 23(5): 141-151. https://doi.org/10.13234/j.issn.2095-2805.2025.5.141
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    With the increasing grid-connected operation capacity of wind turbines, the research on key technologies for their fault ride through (FRT) is becoming more and more urgent. Since the wind turbine with a doubly-fed induction generator (DFIG) is one of the dominant types on the wind power market, researchers have extensively studied the key technologies for the FRT capability of DFIG-based wind turbines. The status quo of researches on the related FRT technologies is reviewed. First, the basic theory of DFIG-based wind turbines is introduced. Then, the analysis methods for the FRT mechanism at present are summed up, and the advantages and disadvantages of different FRT solutions are classified. Finally, the analysis methods and technologies for the FRT of DFIG-based wind turbines are forecasted and summarized.
  • Research on Comprehensive Evaluation Technology for Photovoltaic Power Generation Unit Based on Combined Weighting Method of Minimum Discriminant Information
    ZHANG Jian, XIA Lie, XU Lianghui, YANG Qingbin, DONG Wei
    2025, 23(5): 152-160. https://doi.org/10.13234/j.issn.2095-2805.2025.5.152
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    To further optimize the resource structure, reduce the energy gap and alleviate environmental pollution in China, a scientific evaluation and decision-making mechanism of photovoltaic (PV) power generation projects is in urgent need of establishment, and the comprehensive performance evaluation system of PV power stations should to be improved to promote the sustainable development of the whole social energy system. Focused on the comprehensive evaluation technology for PV power generation units. Based on the basic principle of “multi-criteria, multi-level and multi-factor” decision-making, a comprehensive evaluation system and an evaluation method suitable for PV power generation units are proposed, which comprehensively consider the advantages and disadvantages of objective and subjective weight methods. The principle of minimum discriminant information is used to calculate the combined weight, and a comprehensive evaluation model for PV power generation units is established to compare and analyze the comprehensive evaluation results of a novel PV medium-voltage power generation unit and a conventional PV power generation unit, thus proving the superiority of the design indexes for the novel unit.
  • Research on Lightweight of Hydrogen Fuel Cell Power Supply System Based on MMC and Partial Power Conversion
    GUO Xiaofan, LI Bingyu, DONG Zengbo, JIA Boyan
    2025, 23(5): 161-173. https://doi.org/10.13234/j.issn.2095-2805.2025.5.161
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    A lightweight modular multilevel converter-type fuel cells (MMC-FCs) system based on the partial power conversion (PPC) of FCs is proposed, so as to realize the power control of the FC system which is incorporated into a hybrid medium- and low-voltage network. The MMC-FCs on the AC side based on the synchronous switching network of a high-frequency link (HFL) can realize the coupling cancellation of the sub-module (SM) fundamental frequency and double-frequency ripple power, and reduce the demand of SM capacitance by [2(1-m2/4)3/2fSM]/ [(1+2m2)πfF] times. As a result, the volumes of SMs are reduced, and the lightweight of SMs are realized by improving the power density. The FC system uses partial power control to incorporate the DC low-voltage bus, which reduces the partial power capacity and loss of the FC converter. Meanwhile, the FC converter is reused with the AC HFL square wave power signal to reduce the power conversion stages, thus further improving the lightweight of the system. The structure of MMC-FCs, SM filtering principle, FC PPC mechanism, SM capacitance, FC PPC voltage and other parameters are analyzed and designed in detail. Finally, through an evaluation on volume and losses, the effectiveness of the proposed MMC-FCs scheme was verified by simulation and experimental results.
    • Power System
  • Fault Identification of Multi-terminal MMC-HVDC Grid Based on Fault Current Characteristics
    FU Hua, ZHANG Hui
    2025, 23(5): 174-184. https://doi.org/10.13234/j.issn.2095-2805.2025.5.174
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    To meet the requirements of fast performance and reliability for multi-terminal modular multi-level converter based high voltage direct current (MMC-HVDC) grid protection, a fault identification scheme based on the characteristics of fault current component is proposed. First, the currents under faults inside and outside of a region are analyzed by using the propagation process of the traveling wave component of fault current, and the inside and outside faults are identified through the difference in changes in fault current. Second, the line-mode component is obtained by decoupling the bipolar line, and the polarity of the line-mode component of fault current can be taken as a direction criterion. Third, the calculated ratio between the averages of positive and negative fault currents is used to realize the fault pole selection. A simulation model of multi-terminal MMC-HVDC transmission line is established in PSCAD/EMTDC, and simulation results show that the proposed fault identification method can identify all kinds of faults quickly and accurately only by using the single-terminal fault current characteristics without the need of two-terminal communication, and it also has the capability of anti-overresistance, thereby satisfying the requirements for MMC-HVDC transmission fault protection.
    • Power Quality
  • Analysis of Power Quality of DC Distribution System
    ZHOU Wen, SU Can, HU Xuekai, YAN Peng, MENG Liang, LIU Juncheng
    2025, 23(5): 185-196. https://doi.org/10.13234/j.issn.2095-2805.2025.5.185
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    Owing to its advantages of good controllability, high efficiency and reliability, and adaptability to the connection of renewable energy resources, the direct current (DC) distribution system has become the development direction of next-generation power distribution systems. The characteristics of energy resources and loads, disturbance resources, and operation mechanism of DC distribution networks are different from those of alternating current (AC) distribution networks, which lead to new features of power quality issues. Aimed at the widespread applications of DC distribution systems, their typical topologies with the corresponding grounding modes are introduced. With the combination of operation characteristics, the phenomena of various possible power quality issues in DC distribution systems are analyzed, including voltage band, ripples, imbalance, flicker, voltage dip (short-time interruption) and voltage swell. In addition, the main technical indices that can be used to describe the power quality of DC distribution systems are proposed. The results of an example demonstrate that these indices can well quantitate the related power quality phenomena. Finally, the research directions for power quality issues in DC distribution systems in the future are also discussed. The research aims to analyze the power quality issues in DC distribution systems in depth, providing support for the comprehensive power quality measurement and analysis of DC distribution systems.
    • Wireless Power Transfer
  • Parameter Optimization Method for Wireless Power Transfer System Between Rocket and Ground with LCC-S-type Resonant Network
    WANG Zhan, LAN Kun, ZHANG Jingang, YU Da
    2025, 23(5): 197-206. https://doi.org/10.13234/j.issn.2095-2805.2025.5.197
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    The output characteristics of an LCC-S-type magnetically coupled resonant wireless power transfer(WPT) system are quite different under different parameter configurations. Aimed at the characteristic that the load power on launch vehicles varies in a wide range, a steady-state efficiency model of the WPT system between the rocket and ground was established, and a parameter design method for a resonant network with the average power-efficiency product as an optimization objective was proposed for the first time, so as to improve the system's overall output characteristics in the full power range. On this basis, a time-domain model of inverter output current considering high-order harmonics was built to achieve zero voltage switching of the inverter. In view of the influence of resonance parameter disturbance on indexes such as the switching losses of inverter and the voltage gain, a disturbance design method for resonance network was also given. Finally, the rationality of the model and the superiority of the parameter configuration method were verified by simulation results.
  • Closed-loop Control of Motor Based on Rotational Wireless Power Transfer System
    PAN Zijun, LI Jiangui, WANG Longyang, CHEN Huiying
    2025, 23(5): 207-215. https://doi.org/10.13234/j.issn.2095-2805.2025.5.207
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    The conventional power supply methods for rotary mechanisms have problems such as complex structures, monotonous functions and security risks. Aimed at these problems, a radial-flux rotational wireless power transfer (R-WPT) system with a rotation speed detection function was proposed. First, the relationship between the mutual inductance of a radial-flux coupling coil and rotation angle was deduced, and a circuit model of the R-WPT system was built. Second, an output voltage processing circuit was designed to convert the waveform, which was further used for motor control. Finally, an R-WPT experimental platform driven by a stepping motor was constructed and verified at different target speeds. Results show that the output voltage waveform well conformed to the expectation of deduced mutual inductance. With the voltage signal processing and the closed-loop speed control method based on the stepping motor, the starting process of the R-WPT device with speed regulation can be performed at higher target speeds, indicating the feasibility of the system.
    • Electric Machine System and Control
  • Active Damping Control Strategy for Permanent Magnet Synchronous Motor without Electrolytic Capacitors
    XIE Shihong, CHEN Jinfan, YANG Zhihao, CHEN Jingwen
    2025, 23(5): 216-226. https://doi.org/10.13234/j.issn.2095-2805.2025.5.216
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    Aimed at the shortcomings of large size, susceptibility to damage and high cost associated with electrolytic capacitors in permanent magnet synchronous motor (PMSM) drive systems, an active damping control strategy for PMSM without electrolytic capacitors is proposed by incorporating an RD damping circuit. First, the relationship between the selection of the film capacitor on the DC-bus side and the grid-side input power is analyzed, and the dynamic equations for the DC-bus voltage and capacitance are derived. Then, an active damping power decoupling method based on d-axis repetitive control is put forward to enhance the grid-side current power factor. Meanwhile, a control strategy based on q-axis power transformation is introduced to improve the motor's dynamic negative-impedance characteristics. The RD damping circuit is utilized to simplify control commands and absorb the overshoot voltage. Finally, simulation and experimental results indicate that with the use of small-capacity film capacitors, the active damping control effectively reduces the current distortion and suppresses the torque ripple.
  • Direct Thrust Force Control of Primary Permanent Magnet Linear Motor Based on Adaptive Dynamic Programming
    WANG Xiuping, YAO Shunyu, QU Chunyu
    2025, 23(5): 227-240. https://doi.org/10.13234/j.issn.2095-2805.2025.5.227
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aimed at the problem that the control system for a primary permanent magnet linear motor (PPMLM) is susceptible to uncertain factors such as load disturbance and parameter change, an action-dependent heuristic dynamic programming control algorithm is used to improve the control performance and anti-disturbance capability of the system while reducing the thrust force fluctuation. First, the mathematical model of the direct thrust force control system for PPMLM is constructed. Second, the speed tracking problem is transformed into an optimal control problem, which is further transformed into a problem of solving the Hamilton-Jacobi-Bellman equation by minimizing the performance index function and the speed tracking error. The numerical solution of the Bellman equation is obtained by using a strategy iteration algorithm based on the Bellman criterion. Finally, an accurate tracking of speed is achieved. To solve the problem that the BP neural network is easy to fall into local optimum, an adaptive learning rate is designed. In addition, in view of the problem of approximate error existing in the BP neural network, a robust compensation term is added to the control law to improve the accuracy of speed tracking. Afterwards, the stability of the closed-loop system is analyzed. Simulation results show that the proposed control strategy can improve the speed tracking performance of the system, reduce the thrust force fluctuation and restrain load disturbance and other nonlinear factors.
    • Battery and Energy Storage
  • Estimation of State-of-health of Lithium-ion Batteries Based on Modal Decomposition and Time Series
    CHENG Yan, ZHENG Linhong, LIU Jiang
    2025, 23(5): 241-250. https://doi.org/10.13234/j.issn.2095-2805.2025.5.241
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Aimed at the problem that the prediction results of state-of-health (SOH) of lithium-ion batteries are inaccurate due to the failure to consider the capacity regeneration phenomenon, a nonlinear relationship method based on multi-time scale set empirical mode decomposition fusion time series mapping input and SOH is proposed. The battery capacity information considering capacity regeneration is decomposed into high-frequency main trend signals and low-frequency margin signals by an ensemble empirical mode decomposition (EEMD) algorithm, and the estimation of lithium-ion battery SOH is completed by the prediction results of the two types of signals. Resultsshow that the proposed method can capture the phenomenon of capacity regeneration to improve the estimation accuracy and achieve the fitting of battery capacity degradation, and it is less affected by different prediction starting points. Both the predicted maximum RMSE (root mean square error) and MAE (mean absolute error) are not more than 1.5%, and the maximum MAPE (mean absolute percentage error) is not more than 2%.
  • Optimal Hybrid Energy Storage Capacity Configuration Method for Mitigating Fluctuations of Wind Power
    CHENG Yuming, MENG Gaojun, JIA Peng, WU Yao
    2025, 23(5): 251-261. https://doi.org/10.13234/j.issn.2095-2805.2025.5.251
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Through a comparison of the economic advantages of different power decomposition methods for energy storage system capacity configuration and hybrid energy storage system (HESS) over one single energy storage system, a method based on improved moving average filtering and ensemble empirical mode decomposition (EEMD) is proposed to mitigate wind power fluctuations in view of the optimal capacity configuration of HESS. First, EEMD was used to decompose the HESS reference power which was derived by improved moving average filtering, so as to obtain several single-component signals, i.e., intrinsic mode functions (IMFs). Then, the time-frequency spectrum of each IMF was processed by Hilbert transform to identify the suitable gap frequency, and the HESS reference power was obtained by reconstructing the high- and low-frequency components. Meanwhile, the charge-discharge efficiency of the energy storage system and its state-of-charge were fully taken into account, and the rated power and capacities were configured. Finally, based on the life cycle cost theory, an economic cost calculation model for the energy storage system was established to compare the cost among different configuration schemes, thereby obtaining the optimal one with the highest economic efficiency.
  • Optimal Configuration of Multi-microgrid Shared Energy Storage Considering Stepwise Utilization of Retired Batteries
    WANG Juan, ZENG Guohui, HUANG Bo, LIU Jin
    2025, 23(5): 262-269. https://doi.org/10.13234/j.issn.2095-2805.2025.5.262
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    Under the “Dual-carbon” target, aimed at the problems of excessive investment in microgrid energy storage systems and the arrangement of retired batteries of new energy vehicles, a dual-layer optimal configuration model of a multi-microgrid shared energy storage system considering the stepwise utilization of retired batteries was proposed. First, the multi-microgrid shared energy storage system based on retired batteries was modeled. Second, a dual-layer capacity configuration model was adopted with the investment and operation and maintenance cost of microgrids as its upper-layer objective function and the daily operation cost of energy storage as its lower-layer objective function. The particle swarm optimization algorithm and Cplex linear solver were combined to solve the capacity configuration and equipment running state of shared energy storage. Finally, the result of an example indicates that the proposed model can effectively reduce costs and improve the utilization rate of resources, and the corresponding effect is remarkable.
  • SOH Estimation of Lithium-ion Battery Based on Residual Connection and Conv-LSTM
    ZHOU Bentao, TAO Jili, WANG Qingsong
    2025, 23(5): 270-277. https://doi.org/10.13234/j.issn.2095-2805.2025.5.270
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Lithium-ion batteries are usually taken as energy storage components to realize the storage and utilization of electrical energy, and an accurate estimation of their state-of-health (SOH) can provide a theoretical basis for their actual applications. However, SOH is difficult to measure directly. To estimate the SOH of lithium-ion batteries accurately and conveniently, a model for estimating the SOH of lithium-ion batteries is proposed based on residual connection and convolutional long short-term memory (Conv-LSTM) networks from the perspective of data driven. This method is based on residual connection, Conv-LSTM and convolutional neural networks, and it uses the voltage, current and capacity during the charging process of a lithium-ion battery to realize the SOH estimation in its service cycle. The experimental results on multiple battery test datasets show that compared with those of the existing models with better estimation effects, the estimation result of the SOH estimation model based on residual connection and Conv-LSTM was more accurate, and the maximum percentage error and mean absolute percentage error of SOH estimation on the test dataset were less than 3.3% and 1.7%, respectively.
  • Experiment on Effect of Cell Uniformity and Connection Mode on Performance of SOFC Stack
    LIU Wei, LÜ Jia, SUN Xiaomao, TIAN Liangyu, HU Qiang, WU Jian
    2025, 23(5): 278-288. https://doi.org/10.13234/j.issn.2095-2805.2025.5.278
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    The cell uniformity and connection mode of solid oxide fuel cell (SOFC) are important factors affecting the overall performance of the stack. The uniformity of flat-chip cells in the SOFC stack is evaluated by methods such as linear sweep voltammetry and electrochemical impedance spectroscopy. Then, the comprehensive effect of cell uniformity and connection mode on the stack’s output performance and the underlying electrochemical mechanism are investigated by combining with the method of distribution of relaxation times. Results indicate that the cell uniformity and connection mode jointly affect the stack performance, i.e.,the cell uniformity affects the stack lifetime, while the connection mode affects the stack’s output power. In a series mode, a low cell uniformity will cause the poor-performance cell to over-discharge, which may accelerate the deterioration of the stack performance. Compared with the series mode, the parallel mode will cause a higher power loss, which mainly comes from ohm resistance, oxygen exchange and charge transfer processes but affects the stack lifetime to a small degree. In general, the peak power of the series stack is high,but the lifetime is greatly affected when the cell uniformity is low. The power loss of the parallel stack is obvious, but the influence on the stack lifetime is weak.
    • Reliability and Diagnostics
  • Fault Diagnosis Method for Inverter Based on Data Augmentation with Specific Coefficients Wavelet Reconstruction
    ZHOU Jianyao, WANG Tianzhen, HAN Jingang, TANG Tianhao
    2025, 23(5): 289-296. https://doi.org/10.13234/j.issn.2095-2805.2025.5.289
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The performance of a data-driven fault diagnosis method deteriorates due to insufficient number and unbalanced classes of inverter fault data in the case of weakly supervised learning in few-shot scenarios. To overcome the defect of traditional data augmentation methods which do not consider the data distribution characteristics, an inverter fault diagnosis method based on data augmentation with specific coefficients wavelet reconstruction was proposed. First, the raw small sample data was decomposed by wavelet packet, and a specific coefficient was obtained through calculation. After random fine-tuning, the sample was directly expanded by wavelet packet reconstruction. The process was repeated to obtain a sufficient and class-balanced training set. Then, convolutional neural networks were used to achieve “end-to-end” fault feature extraction and classification. Finally, experimental results show that the proposed method can effectively expand the fault data in the case of weakly supervised learning in few-shot scenarios and improve the fault diagnostic accuracy. Therefore, it can be used as data preprocessing in few-shot fault diagnosis of inverters.
    • Special Power Supply
  • Design and Research of Miniaturized High-voltage AC Plasma Power Supply Module
    WANG Weiqian, LI Zhanxian
    2025, 23(5): 297-305. https://doi.org/10.13234/j.issn.2095-2805.2025.5.297
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The air discharge plasma technology has become an important research direction of plasma medicine. In general, the plasma discharge power supply takes the mains power or a large-scale regulated power supply as its input. This kind of power supply is too large in size to meet the application conditions of portable, wearable and attachable plasma generators, which limits the practical applications of the plasma technology in biomedical field. Under this research background, a plasma power supply with a piezoelectric ceramic transformer as its core was designed and studied to meet the requirements of miniaturization and portability for power supply. The size of this power supply was 50 mm×15 mm×8 mm, and its weight was 12.1 g. The power drive circuit adopted a chip-driven oscillating half-bridge circuit, and its main circuit included a step-up Boost circuit and a step-down Buck circuit. The results of no-load and on-load discharge tests show that when the power supply was supplied with 3.7 V power input, the no-load discharge voltage can be adjusted from 200 V to 2.2 kV, the output frequency was 52 kHz with fluctuation of 1 kHz, the maximum output power was 7 W, and the power weight ratio was 580 W/kg, which was better than the common plasma power supplies on the market. Through experimental tests, it is found that the application of this power supply can make SDBD and FE-DBD plasma generators discharge to produce cold plasma. Its miniaturization and portability are of significance to the application of wearable and attachable plasma generators.
    • EMI/EMC
  • Research on EMI Characteristics of Three-level Converter with Hybrid Devices in Different PWM Modes
    LI Jin, JIAO Nana, HUANG Minchao, FAN Yushun, DANG Enshuai
    2025, 23(5): 306-315. https://doi.org/10.13234/j.issn.2095-2805.2025.5.306
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The topology of a three-level active neutral point clamped (3L-ANPC) converter with hybrid devices of SiC-MOSFET and Si-IGBT was taken as the research object to study the common-mode electromagnetic interference (CM EMI) characteristics in three pulse width modulation modes. First, two combination modes of SiC-MOSFET and Si-IGBT and three modulation modes of the 3L-ANPC converter topology were introduced. Then, the propagation mechanism of CM noise in the 3L-ANPC converter was analyzed. Based on the analysis, an EMI model including parasitic parameters and noise sources was established, and the impedance expression of propagation path in each modulation mode was derived, thereby obtaining the impedance characteristic curves of CM propagation paths. Finally, the conclusion about the CM noise of the 3L-ANPC converter with hybrid devices in three modulation modes was experimentally verified.
  • Prediction and Suppression of Common-mode EMI Noise for Push-pull Converter
    WU Yuezhe, ZHENG Chengjun, DU Zikai, MA Kuian, REN Xiaoyong, CHEN Qianhong
    2025, 23(5): 316-323. https://doi.org/10.13234/j.issn.2095-2805.2025.5.316
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    As a typical isolation topology, the push-pull converter has been widely applied in high-reliability scenarios because the transformer is bidirectionally magnetized and the input does not have the risk of bridge arm straight through. With an increase in the converter's operating frequency, the influence of common-mode interference becomes obvious. Therefore, the common-mode noise modeling analysis of the converter has important theoretical and application value for its electromagnetic compatibility optimization design. For a four-winding transformer with a central tap on both the primary and secondary sides, its two-capacitance parasitic parameter model is established in this paper. On this basis, a common-mode noise model in the frequency domain of the push-pull converter is established. Through the analysis of the common-mode noise source and the conduction path of common-mode noise, the prediction of common-mode noise is realized. To enhance the practicability of the model, the extraction method for parasitic capacitance parameters of the transformer is discussed for the simplified transformer model, and a common-mode noise suppression method based on a balancing capacitor is proposed. The accuracy of the established common-mode noise model and the effectiveness of the common-mode noise suppression method were verified by experimental results.
  • Design of Reduced On-board EMI Filter Volume Using Spread Spectrum Modulation Technology
    CHEN Guohang, YANG Wenrong, LUAN Junling, ZHANG Haojie, WANG Yixuan
    2025, 23(5): 324-332. https://doi.org/10.13234/j.issn.2095-2805.2025.5.324
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    A passive electromagnetic interference (EMI) filter can effectively suppress the conducted EMI of an on-board DC-DC converter at the cost of increasing the volume and cost of equipment, which runs counter to the original intention of high-power density design of electronic equipment. The suppression of conducted EMI by the combination of spread spectrum modulation and the filter can effectively reduce EMI and the filter volume as well. First, the method and process of EMI filter design are studied. Second, the principle of reducing EMI by spread spectrum modulation is analyzed. Combined with the calculation method for filter cut-off frequency, the optimal spread spectrum parameters are calculated, which increases the cut-off frequency in the design of a common-mode choke coil and effectively reduces the filter size. Finally, experimental results show that the spread spectrum modulation combined with the filter has a good suppression effect on the EMI of the on-board DC-DC converter, and the volumes of a compact common-mode choke coil and a filter after the spread spectrum modulation are reduced by 63% and 44% respectively compared with those of a common-mode choke coil and a filter used in the fixed frequency modulation.
Volume 23 Issue 5
30 September 2025
Supervised by:
China Association for Science and Technology
Sponsored by:
China Power Supply Society
National Ocean Technology Center
Edited by: Editorial Department of JOURNAL OF POWER SUPPLY
Distribution in China: Local Post Offices or Online subscription
Editor-in-Chief: Jiaxin Han
Acting Editor-in-Chief: Xinbo Ruan
Co-Editor-in-Chief: Xiong Du and Wu Chen
Editorial Manager: Guozhen Chen
CN: 12-1420/TM
ISSN: 2095-2805
Postal Code in China: 6-273
International Postal Code: BM8665
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