Journal of Power Supply

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Bi-directional DC-DC Converter of Vehicle Charging Pile Based on Sliding Mode Active Disturbance Rejection Control

ZHU Longji, YANG Jing

Journal of Power Supply. 2025, 23(8): 1-11. https://doi.org/10.13234/j.issn.2095-2805.2025.8.1

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Bi-directional DC-DC convertersare usually used in vehicle charging pile application circuits, which have problems such as slow system dynamic response and poor output voltage stability due to load perturbations. On the basis, acapacitor-inductor-inductor-capacitor (CLLC) resonant DC-DC converter is taken as a research object, and a control method for the CLLC resonant converter based on sliding mode active disturbance rejectionis proposed. A model-assisted linear state observer is used to improve the estimation accuracy of perturbation, so as to control the stable operation of the system. Sliding mode control is used to design a linear state error feedback control law to improve the dynamic performance and rapidity of the system. Simulations and experimental verification show that the proposed control strategy can effectively improve the dynamic response of the bi-directional DC-DC converter and enhance the output voltage stability.

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ZVZCS Switched Capacitor Converter with High Efficiency

SONG Weibo, ZHANG Zhe

Journal of Power Supply. 2025, 23(8): 12-21. https://doi.org/10.13234/j.issn.2095-2805.2025.8.12

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Aimed at the hard-switching issues associated with the traditional zero current switching (ZCS) switched capacitor converters (SCCs), a zero voltage and zero current switching (ZVZCS) DC-DC SCC based on an LC auxiliary network is proposed, which can achieve zero voltage switching (ZVS) for all switches throughout the entire operating range. Under certain conditions, it can also simultaneously achieve both the ZVS and ZCS, significantly reducing the switching losses. On this basis, an in-depth investigation into the impact of dead time on converters is conducted, revealing a quantitative relationship between dead time selection under different load conditions and converter loss distribution. Subsequently, a design methodology for key parameters of auxiliary networks based on dead time is put forward. Finally, based on the proposed ZVZCS SCC, a 24 V DC-12 V DC experimental prototype with 100 W was constructed with a peak efficiency of 99.07%, thus validating the correctness of the theoretical analysis.

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Hybrid Compensation Scheme Based on Buck Converter with Variable Output Capacitance

ZHANG Shusen, SHEN Hanxin, ZHENG Qingliang

Journal of Power Supply. 2025, 23(8): 22-32. https://doi.org/10.13234/j.issn.2095-2805.2025.8.22

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A hybrid compensation scheme based on variable output capacitance is proposed to improve the start-up speed and anti-load impact capability of a non-ideal peak current mode (PCM) Buck converter, under which the loop stability and dynamic response performance are ensured while realizing the synchronous switching of output capacitance and loop compensation parameters. A complete small-signal model of the non-ideal PCM Buck converter is established, the open-loop transfer function of the system is analyzed to obtain the influence of different output capacitance parameters on the compensation network, and the design of reasonable loop compensation is carried out. Simulation results show that the compensated system can maintain the crossing frequency around 10 kHz (1/20 fsw) and the phase margin around 70° under a variety of conditions. Moreover, a synchronous switching circuit of output capacitance and compensation parameters is designed. Finally, a 15 W experimental prototype was built, and experimental results further verified the feasibility of the proposed scheme.

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Analysis of Soft Switching Modulation Strategy for Bidirectional Isolated DC-DC Converter

LI Yanlong, LIU Chaohou, ZHANG Chunxu, YANG Yang, YAO Yousu

Journal of Power Supply. 2025, 23(8): 33-42. https://doi.org/10.13234/j.issn.2095-2805.2025.8.33

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With the vigorous development of electric vehicles and energy storage industries, the power electronics technology has been applied on an increasing scale. In these applications, power electronic converters not only require wide voltage gain to adapt to different scenarios, but also require a high conversion efficiency to reduce volume. Therefore, bidirectional isolated DC-DC converters with soft switching have been widely studied. On the basis, the principle of isolated DC-DC converters was analyzed, and the conversion efficiency under wide voltage gain was improved by reducing the reactive power current and implementing soft switching. First, a mathematical model was established through fundamental wave analysis to obtain the conditions for controlling the phase shift angle on the primary side, secondary side, and both the primary and secondary sides to achieve reactive power current elimination. Then, the conditions for achieving soft switching of switching devices on the primary and secondary sides were analyzed, and the dead time was designed to adjust the phase shift angle between the primary and secondary sides, so that a modulation strategy for achieving ZVS with minimal reactive power current was obtained. Finally, a 9.6 kW experimental prototype was designed to verify the feasibility of the proposed modulation strategy.

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Highly Reliable Current-source Inverter with Continuous Path of Inductive Current

XIE Pengyao, ZHU Caihui, YI Zihan, QIU Jian, ZHAO Hui, LIU Kefu

Journal of Power Supply. 2025, 23(8): 43-51. https://doi.org/10.13234/j.issn.2095-2805.2025.8.43

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A current-source inverter (CSI) possesses several advantageous features, including stable output current, a wide load range and immunity to current surges during load open-circuit conditions. In applications where reliability is critical, CSIs outperform voltage-source inverters (VSIs). However, traditional CSIs suffer from significant current droop during continuous discharge and the risk of overvoltage at the inductor terminals when the load is open-circuited, limiting their practical utility. To address these limitations, the relative positions of the inductor, switches and diodes within conventional CSIs are modified, so as to enable energy replenishment during continuous discharge. Meanwhile, a continuous current path through the inductor is ensured to effectively prevent overvoltage across the inductor terminals. A detailed theoretical analysis of the proposed circuit is conducted, and it is verified by simulations. Finally, an experimental prototype was designed to further validate the feasibility of this circuit.

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System Model-based Composite Control for Three-phase PWM Converter

ZHANG Yanli, ZHOU Keliang, HE Qingqing, TANG Chao, WANG Zhong

Journal of Power Supply. 2025, 23(8): 52-59. https://doi.org/10.13234/j.issn.2095-2805.2025.8.52

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For a system with deterministic models of control objects such as power electronic converters and electric motors, a system model-based composite control strategy is proposed by combing a full state feedback (FSF) controller and ageneralized integrator (GI). First, compared with the proportional-integral-derivative (PID) and proportional-resonant (PR) controllers, this strategy canfully take advantage of the knowledge and information about the system model, so as to simplify the controller design and improve the system’s control performance. Then, based on the system-based model including the control object, the combination of a reference/disturbance model and an FSF closed-loop system model provides a simple and universal design approach for the composite control without the need for time-consuming trial and error. Finally, the proposed composite control strategy was applied to a 3 kVA three-phase PWM inverter, and results verified the feasibility of this strategy.

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General Graphical Evaluation Method for Capacitor Current Feedback Active Damping Characteristics of LCL Grid-connected Inverter and Its Applications

LI Zhi, ZENG Chuihui, XIE Jun, WANG Wei, YAO Jun, ZHANG Jie

Journal of Power Supply. 2025, 23(8): 60-69. https://doi.org/10.13234/j.issn.2095-2805.2025.8.60

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The capacitor-current feedback active damping is widely applied to attenuate the LCL resonance. Due to the control delay, the virtual impedance equivalence of active damping may exhibit a negative-damping effect, challenging the system stability. To address this issue, the feedback function should be well selected and designed according to the LCL resonance frequency. On the basis, a general graphical evaluation method is proposed, which can intuitively identify the positive-damping frequency ranges of different feedback functions and thus provide guidance for selecting a reasonable active damping feedback function. Using the proposed method, a phase-lag compensator with strong robustness against the fluctuation of LCL resonant frequency is put forward. Experiments were carried out on a 6 kW single-phase LCL grid-connected inverter, and results verified the theoretical analysis.

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Coordinated Control Method for Suppressing Current Distortion of Swiss Rectifier under Unbalanced Power Grid

JIANG Weidong, LIU Xinran, ZHONG Min, LIU Shengyu, YANG Liu, XU Xingyu

Journal of Power Supply. 2025, 23(8): 70-81. https://doi.org/10.13234/j.issn.2095-2805.2025.8.70

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Owing to their advantages such as high efficiency and simple control, Swiss rectifiers show promise in the field of electric vehicle charging. Under conditions of unbalanced power grid, the use of traditional control methods will lead to the generation of even-order harmonics on the DC side and odd-order harmonics on the AC side of a Swiss rectifier, thereby affecting the system operation. On the basis, two control methods for the Swiss rectifier under unbalanced power grid conditions are introduced, i.e., constant output voltage control (COVC) and sinusoidal and symmetrical current control (SSCC). With COVC, the DC voltage remains stable at the cost of negative-sequence current emerging in the input current, which results in a phase difference between the grid voltage and current of the Swiss rectifier. Due to constraints on the topology, this phase difference may lead to grid current distortion. SSCC ensures a symmetrical and sinusoidal current, but significant fluctuations in the DC voltage may exist. To solve these problems, a coordinated control method of suppressing current distortion control (SCDC) is proposed, which can realize sinusoidal input current throughout the entire grid voltage drop range while minimizing the fluctuations of active power. The effectiveness of the SCDC method was verified by experimental results.

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Predictive Fault-tolerant Control Strategy Based on Model with Fixed Number of Calculations for MMC Converter without Redundant Submodules

YANG Chengshun, ZHANG Chenxi, XU Dezhi, XU Kunshan, ZHANG Binfeng

Journal of Power Supply. 2025, 23(8): 82-92. https://doi.org/10.13234/j.issn.2095-2805.2025.8.82

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To address the challenges of a modular multilevel converter (MMC) without redundant submodules when using the traditional PI control method for fault-tolerant control, which include excessive control parameters, complex structure and slow dynamic responses, a model with a fixed number of calculations for implementing the fault-tolerant control by fault prediction is proposed. First, the AC current is optimized. Then, multi-objective optimization on the circulating current and the total voltage of submodule capacitors is performed, and the balance of submodule voltage is realized based on the direction and level difference of bridge arm current. With only eight times of rolling optimization, the optimal solution can be found under this strategy, significantly reducing the computational requirements. In addition, this algorithm not only can ensure that the MMC operates stably and has high-quality output under normal conditions, but also can maintain its stable operation when the submodule experiences an asymmetric fault. Simulation tests were completed in MATLAB/SIMULINK, and a five-level experimental platform was built to verify the simulation and test results.

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Characteristics of Arm Multiplexing MMC under Three-phase Short-circuit Faults and Corresponding Fault Ride-through Strategy

ZHANG Houyi, LI Jikai, XU Yutao, YAN Xin, FENG Qihui

Journal of Power Supply. 2025, 23(8): 93-104. https://doi.org/10.13234/j.issn.2095-2805.2025.8.93

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In practical engineering, the issues of large equipment volume and high operating costs increasingly highlight the demand for lightweight modular multilevel converters (MMCs) in new power systems. The arm multiplexing MMC (AM-MMC) can improve the utilization of submodules and effectively achieve lightweight MMC. However, due to its complex topology and susceptibility to fluctuations in internal energy caused by the changes in operating conditions, the energy fluctuations are more severe and even prone to reuse errors, especially in the event of AC system failures, increasing the requirements for the AC fault ride-through capability of AM-MMC. For the three-phase short-circuit fault of the AC system under the most serious fault condition, the fault characteristics of the converter after the fault are analyzed, and an optimal configuration strategy for the fault capacitor based on a fast blocking mechanism is proposed. During the fault period, the multiplexing mode adjustment and the fast blocking are carried out simultaneously to realize the fault ride-through of the AM-MMC after the three-phase short-circuit of the fault ride-through AC system. Finally, to validate the proposed strategy, a singleended simulation model was constructed using MATLAB/ Simulink. Simulation results demonstrate that re-locking the converter after switching the multiplexing mode can effectively resolve the three-phase short-circuit fault ride- through issue in the AM-MMC.

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Control Strategy for Modular Multilevel Matrix Converter Based on Bridge Arm Energy Control

XU Mingliang, YAO Yousu, YANG Yang, HANG Lijun

Journal of Power Supply. 2025, 23(8): 105-114. https://doi.org/10.13234/j.issn.2095-2805.2025.8.105

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The modular multilevel matrix converter (M3C) has a cascaded modular structure, which is suitable for scenarios with medium- and high-voltage, high power and wide frequency ranges such as driving high-voltage high-power motors and flexible low-frequency transmission systems. However, due to the large number of system components and the presence of floating capacitors, the difficulty in controlling the M3C is significant, especially in terms of voltage equalization and ripple suppression of numerous floating capacitors in the system. A strategy based on bridge arm energy control is proposed, which is intuitive and simplifies the number of control layers. The goal of directly controlling the energy of each bridge arm in the converter is mainly achieved by setting the energy reference value of the bridge arm and controlling the bridge arm energy at present in real-time in the form of negative feedback. Aimed at each cascaded submodule within the bridge arm, a voltage equalization controller is designed. Finally, the feasibility of the proposed control strategy was verified through simulations.

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Research on Control-protection Coordination Technology for Microgrids Based on Harmonic Component Injection

XUE Linyi, MU Longhua, XU Ruijie

Journal of Power Supply. 2025, 23(8): 115-123. https://doi.org/10.13234/j.issn.2095-2805.2025.8.115

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Since the inverter-interfaced distributed generations (IIDGs) in microgrids exhibit special output characteristics, traditional protection schemes are no longer suitable for microgrids. Simultaneously, the idea of “Signal-injected active protection” introduces a novel perspective on microgrid protection. However, the shunt problem of non-injection source results in a poor protection performance. Under this background, in light of the idea of control-protection coordination, an active protection method for microgrids based on harmonic component injection is proposed. First, the frequency response characteristics of IIDG are analyzed. Then, the controllers of injection source and non-injection source are designed, and the corresponding start-up criteria are established. When a fault occurs, the injection source injects the characteristic signal of harmonic component with constant amplitude into the microgrid, while the non-injection source limits the shunt of the characteristic signal, so that the characteristic frequency equivalent network of the microgrid exhibits a single-source structure. Simulation results show that the proposed strategy can reliably start the harmonic component injection and solve the shunt problem of the characteristic signal, providing a solution for signal-injected microgrid protection.

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Inertia Evaluation and Frequency Modulation Control Parameter Setting for Photovoltaic Grid-connected System

YE Chengwei, HE Zhen, ZENG Pingliang, HANG Lijun, LIU Yingming

Journal of Power Supply. 2025, 23(8): 124-134. https://doi.org/10.13234/j.issn.2095-2805.2025.8.124

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As the proportion of photovoltaic installed capacity continues to increase and the low inertia problem inpower systems becomes increasingly prominent, how to evaluate the inertia supporting capacity of a photovoltaic grid-connected system and how to set the frequency modulation parameters of the system to meet the requirements of grid-connected guidelines are the key issues to be solved urgently. The equivalent inertia of a typical grid-connected photovoltaic system with additional frequency modulation control is quantitatively evaluated by analogizing the rotor motion equation of synchronous generators. Then, considering the physical constraints of photovoltaic equipment and the requirement of new energy grid-connected guidelines, the frequency modulation control parameter setting method for a centralized photovoltaic grid-connected system is put forward. Furthermore, based on the physical constraints and grid-connected guideline requirements, a target of minimum network line loss is introduced additionally, and the frequency modulation control parameter setting method for a distributed photovoltaic grid-connected system is formulated. Finally, the simulation results based on MATLAB/Simulink verify the correctness of frequency modulation control parameter setting.

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Research on Capacitive Energy Extraction Mode, Reactive Power Compensation and Dynamic Voltage Regulation Modulation Technology

SHI Yuhao, HU Kangtao, CHEN Xiaojun, CHEN Tao, YANG Lanjun

Journal of Power Supply. 2025, 23(8): 135-144. https://doi.org/10.13234/j.issn.2095-2805.2025.8.135

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Due to its advantages of stable power and low cost, the capacitive energy extraction mode is suitable for local power supply scenarios of pole switches in medium-voltage distribution networks. The output characteristics of a capacitive energy extraction circuit are often in an approximate constant-current source range, and the primary voltage is required to normally supply power in the range of 5.7-42 kV under different operating conditions in the meantime, so voltage regulation measures must be taken to provide stable voltage for the load. First, based on the compensation characteristics in the capacitive energy extraction mode, a secondary reactive power compensation mode is proposed to make up for the difference between the energy extraction power and load consumption. Second, a voltage modulation dynamic reactive power compensation scheme based on PWM is put forward, so that the dynamic reactive compensation is realized through dynamic equivalent reactance. Third, a waveform modulation dynamic reactive power compensation scheme is constructed, and the transformer voltage waveform is actively controlled through the H-bridge of the third winding, thus realizing the reactive power dynamic voltage stabilization in the capacitive energy extraction mode. Under the proposed voltage stabilization and regulation scheme, the stable AC voltage output under low heat generation in the capacitive energy extraction mode is realized.

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Short-term Charging Load Forecasting for Electric Vehicles Based on Combined LSTM-GNN Model

LIU Yizhou, LI Zhenhua, WEI Wei, LI Zhenxing, XU Yanchun, ZHANG Lei

Journal of Power Supply. 2025, 23(8): 145-156. https://doi.org/10.13234/j.issn.2095-2805.2025.8.145

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In the context of new energy era, aimed at the hot issue of the impact of electric vehicle charging loads on power grid, a short-term charging load forecasting method for electric vehicles based on a combined long short-term memory network and graph neural network (LSTM-GNN) model is proposed to address the shortcomings of existing models. First, three typical daily loads are correlated using the Copula theory, a feature input matrix containing the main factors and historical loads of charging stations is constructed, and a sliding window data set is established. Second, LSTM and GNN are used for feature extraction and graph data construction of the feature input matrix, and the GNN layer completes the feature aggregation and outputs the predicted load value and error evaluation indexes. The results of an example show that the proposed model can effectively extract the key features of charging load at charging stations in different regions, and it has better forecasting performance and generalization capability than traditional models.

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Analysis of Leakage Inductance and Input Current Harmonics for Isolated 18-pulse Rectifier Transformer

LIU Hao, KONG Lingling, YU Siyu

Journal of Power Supply. 2025, 23(8): 157-166. https://doi.org/10.13234/j.issn.2095-2805.2025.8.157

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The multi-pulse rectifier technology has advantages such as simple realization, low cost and high reliability, and it has been widely applied in high-power rectifier systems. Based on the topology of a traditional D-type 18-pulse autotransformer, a triangle is added to connect the primary side to form an isolated 18-pulse rectifier transformer, which is further used in a DC distribution system. Its circuit, working principle, output DC voltage and input current harmonics are analyzed theoretically in detail. In addition, the software Ansys-Maxwell is used to perform equivalent modeling of the transformer, and the reliability of simulation results is verified by a comparison with the theoretical analysis. Two methods of leakage flux method and short-circuit experiment are used to solve the primary-side leakage inductance of the transformer. The input current harmonics of the transformer are analyzed in depth, and the influence of transformer leakage inductance on the suppression of input current harmonics is also discussed.

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Event Triggering Control of Active Power Filter Based on Switching Model

YU Fangzhou, LI Qiang, HOU Jia, LÜ Xiaofeng, ZHANG Fan

Journal of Power Supply. 2025, 23(8): 167-173. https://doi.org/10.13234/j.issn.2095-2805.2025.8.167

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To improve the transient-and steady-state performance indexes for an active power filter (APF) and reduce the steady-state switching loss, an APF event triggering control based on a switching model is proposed. By establishing the dynamic model of the APF system and combining with the Lyapunov function, the constraint conditions satisfying the system stability are obtained, according to which the design range of parameters when the system reaches its steady state is analyzed and the switch vector selection method in a normal operation mode is obtained. On this basis, the switching principle for the controller is formulated, so that the APF system can quickly track the target current and reduce the number of switching tube actions on the premise of ensuring the control accuracy when it reaches the steady state. Finally, the correctness and superiority of the proposed design method were proved by simulation and experimental results.

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Optimization Method for Structural Parameters of WPT System Based on IPSO-BP Algorithm

LI Zhenjie, BAI Yuhong, LIU Yiqi, BAN Mingfei

Journal of Power Supply. 2025, 23(8): 174-181. https://doi.org/10.13234/j.issn.2095-2805.2025.8.174

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To improve the transmission efficiency of a wireless power transfer (WPT) system, its structural parameters were optimized. Considering the low efficiency and poor comprehensiveness of the traditional optimization methods when designing the WPT system’s structural parameters, a parameter optimization model for an SS-type WPT system was established to determine the optimization parameters. On this basis, a structural parameter optimization method for the WPT system was proposed, which integrated orthogonal experiments, finite element simulation and improved particle swarm optimization-backpropagation neural network algorithm. Experimental results show that the average error between the predicted and experimental values was 4.3%, indicating that the proposed optimization method is reasonable, feasible and of reference significance for the structural parameter optimization of WPT systems.

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Magnetic Field Shielding Optimization for DD Coil-based Electric Vehicle Wireless Charging System

WANG Xinyue, ZHANG Liyan, CHEN Qihong, ZHOU Ze

Journal of Power Supply. 2025, 23(8): 182-190. https://doi.org/10.13234/j.issn.2095-2805.2025.8.182

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The wireless charging technology for electric vehicles can overcome the shortcomings of traditional wired charging methods such as low convenience and high safety risk, but the magnetic flux leakage in its transmission process may lead to electromagnetic interference and even pose a threat to human health. To solve the magnetic flux leakage problem in wireless charging, the magnetic field distribution around a high-power DD coil is studied, and a novel active shielding design is proposed, i.e., the active shielding coil is directly connected in series with the primary coil to reduce the leakage magnetic field. At the same time, the additional coupling between the shielding coil and the receiving coil of the wireless charging system is eliminated. In addition, multi-objective optimization is performed to determine the optimal parameters of the shielding coil with the maximum magnetic flux density of the target surface, the output power of system load and the system transmission efficiency as the objective functions. Finally, a 5 kW experimental prototype was built to verify the analysis results and investigate the effect of the shielding coil on the system parameters. Results show that the optimized shielding design reduces the magnetic field intensity in the target region by 33.5%, while the power and efficiency of the wireless charging system are not significantly reduced.

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Coplanar Dual-branch Wireless Power Transfer System with Constant Output

FENG Qunqun, YIN Jiabin, XIONG Biao, LUO Bin

Journal of Power Supply. 2025, 23(8): 191-199. https://doi.org/10.13234/j.issn.2095-2805.2025.8.191

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In the multi-load wireless charging field, it is often necessary to provide constant voltage (CV) or constant current (CC) output for charging the receiving equipment. However, in the existing research on the multi-load wireless power transfer (WPT) system, there is usually just one mode, i.e., CV or CC, and the work in which both the CV output and CC output are provided is seldom reported. A coplanar two-branch WPT system was proposed, which can provide two branches of load-independent output, i.e., one CC output and another CV output. The two branches can be designed independently without affecting each other. By switching control or moving away one branch, three kinds of power supply modes can be provided, i.e., both the CC and CV branches, only the CV branch, and only the CC branch. First, the topological structure of the two-branch WPT system was introduced, and the principle of load-independent and two branches operating independently was explained in detail. Second, the influence of loss on the system performance and the estimation method for the dynamic range of load were revealed. Finally, a two-branch experimental platform consisting of five resonators was built, and the experimental and theoretical results were in good agreement. By inserting ferrite plates to the junctions of coplanar adjacent coils, the magnetic coupling between adjacent coils was enhanced significantly, and the system transmission efficiency was improved as a result. In the three operating modes (i.e., charging only the CC load, only the CV load, or both the CC and CV loads simultaneously), the measured maximum transmission efficiency reached 89.2%, 93.5% and 91.6%, respectively.

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Research on Efficiency Optimization Method for Dual-transmitter Wireless Charging System

BAN Mingfei, ZHOU Tao, LI Zhenjie, LIU Yiqi

Journal of Power Supply. 2025, 23(8): 200-207. https://doi.org/10.13234/j.issn.2095-2805.2025.8.200

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Charging efficiency is an important index for evaluating the performance of a wireless charging system. A dual-loop control method based on current proportion is proposed to improve the charging efficiency of a layered magnetic coupling wireless charging system with dual transmitting coils, which can achieve constant voltage and constant current output while improving the system efficiency by approximately 4%. First, the working principle for the dual-transmitter wireless charging system based on LCC-S compensation network is introduced, a mutual inductance model is established, and the relationship between output voltage and current is deduced. Then, the coupling relationship between the changes in mutual inductance and system efficiency is studied, and a double closed-loop control method based on the optimal current proportion is proposed to achieve constant current and constant voltage output by outer-loop control and efficiency optimization by inner-loop control current distribution. Finally, the feasibility of the double closed-loop control strategy with optimal efficiency was verified by simulations and an experimental platform with 250 W.

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Interference Shielding Characteristics of UAV Wireless Power Supply Pile Based on Magnetic Coupling Resonance

ZHAO Hang, JIA Jing, CHEN Xiaofei, AN Mei, YANG Lei, CHEN Xuena

Journal of Power Supply. 2025, 23(8): 208-216. https://doi.org/10.13234/j.issn.2095-2805.2025.8.208

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The navigation safety of UAV depends on the normal operation of its electronic equipment and sensors. Electromagnetic interference may lead to errors or failures of flight control systems, affecting the flight path and stability. The use of metal materials can effectively shield the electromagnetic field, but the introduction of metal will change the magnetic field characteristics of the system, resulting in the detuning of the compensation network and leading to the power supply system output power deviation and low efficiency. To study the electromagnetic shielding effect of aluminum-ferrite and the influence of the shielding structure on the electrical parameters of a magnetically coupled resonant wireless power supply system, the influence of the aluminum plate on the spatial magnetic field is studied at first, and the variations of the coil self-inductance, mutual inductance and the magnetic induction intensity in the non-working area are analyzed. Then, ferrite is added to improve the electrical parameters, so that the self-inductance and mutual inductance of the coil are close to the initial values. Finally, simulation results verified that the electromagnetic radiation in the non-working area met the safety standards. In addition, an experimental platform was built to analyze the characteristics of output parameters and verify the effectiveness of the shielding structure.

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Research on Self-alignment Method of Wireless Power Transfer Coils for Rotorcraft Unmanned Aerial Vehicles

LI Zhenjie, CUI Hang, YUAN Dechun, ZHOU Tao, LIU Yiqi

Journal of Power Supply. 2025, 23(8): 217-225. https://doi.org/10.13234/j.issn.2095-2805.2025.8.217

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Aimed at the problem of lateral offset in the magnetic coupling device of a wireless charging system for rotorcraft unmanned aerial vehicles (UAVs), a self-alignment method of coils is proposed by collecting the output voltage while moving the transmitting coil and adjusting its position according to the value of the collected output voltage. First, a mutual-induction model is established to analyze the electrical and magnetic characteristics of the wireless charging system, thereby deriving the expression of the relationship between the output voltage and the lateral distance between the transmitting and receiving coils. Then, the size of a magnetic coupler is designed based on the size of the alignment region, and the alignment regionis divided. Additionally, a specific alignment process is outlined. Finally, an experimental platform was established to conduct self-alignment experiments on the transmitting and receiving coils. Based on the experimental results, it is evident that the proposed method can effectively achieve self-alignment of coils with an alignment accuracy of less than 1.5 cm, meeting the requirements for efficient wireless charging of UAVs.

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Constant Voltage and Constant Current Wireless Charging System with Automatic Reconstruction of Topology

SU Junping, QIU Chun, ZHANG Chentao

Journal of Power Supply. 2025, 23(8): 226-234. https://doi.org/10.13234/j.issn.2095-2805.2025.8.226

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The battery charging process typically consists two stages, i.e., constant current (CC) followed by constant voltage (CV). However, the existing wireless power transfer (WPT) technology still encounters several challenges during the transition from the CC mode to CV mode, including battery state monitoring, requirement for bilateral communication and cross-coupling among multiple coils. To address these problems, a novel quasi-CLC-LCC topology is proposed, which can realize the smooth transition from the CC mode to CV mode without the need for additional control. A CLC compensation network is employed by the transmitter circuit, enabling the transmitting coil current to be considered as a CC source. On the secondary side, two series compensation circuits are connected in parallel, and two branches collaboratively achieve CC charging for the battery at the initial charging stage. As the charging process progresses, owing to the unidirectional conductivity of diodes, one of the branches is clamped and disconnected, enabling the WPT system to enter into CV output. Finally, an experimental platform with 2.6 A charging current and 105 V charging voltage was constructed to validate the feasibility of the proposed wireless charging topology.

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Research on Residual Vector Reconstruction Based Fault- tolerant Strategy for Open-end Winding Motor Drive System

ZHU Yueting, YANG Shuying, ZHANG Yufeng, ZHANG Xing, WANG Hanyu

Journal of Power Supply. 2025, 23(8): 235-245. https://doi.org/10.13234/j.issn.2095-2805.2025.8.235

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To realize the fault-tolerant control without adding extra hardware, a residual vector reconstruction strategy is proposed for an open-end winding motor drive system with isolated DC buses under the open-circuit fault of one switch. Meanwhile, the maximum utilization of residual voltage vectors is achieved, so that the operation performance of the drive system in its fault-tolerant operation is improved to a great extent. Furthermore, a phase duty cycle method is used to optimize the switching sequence in order to solve the problem of imbalanced switching action during the vector synthesis process. As a result, the switching action is balanced. Finally, the operation result under the proposed fault-tolerant strategy was analyzed in depth, and the operation performance of the system after fault was validated through a hardware-in-the-loop experiment.

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SOC Estimation of Lithium-ion Battery Based on ISSA-ELM Algorithm

KOU Farong, YANG Tianxiang, LUO Xi, MEN Hao

Journal of Power Supply. 2025, 23(8): 246-253. https://doi.org/10.13234/j.issn.2095-2805.2025.8.246

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To improve the accuracy of state-of-charge (SOC) estimation for lithium-ion batteries, an SOC estima- tion method based on an improved sparrow search algorithm optimized extreme learning machine is proposed. In response to the problem of unsatisfactory estimation accuracy caused by the improper number of neurons in the hidden layer of the extreme learning machine, the sparrow search algorithm is selected to optimize the number of neurons in the hidden layer of the extreme learning machine. To avoid the problems of poor diversity of randomly generated populations and the tendency to fall into local optima at the later stage of the sparrow search algorithm, Tent chaotic mapping and the Metropolis criterion in a simulated annealing algorithm are introduced to improve the sparrow search algorithm’s global search capability. The advantages of the proposed algorithm in terms of accuracy and efficiency compared with the traditional extreme learning machine and long short-term memory networks were verified through simulation experiments under FUDS operating conditions at room temperatures. Finally, a dSPACE hardware- in-the-loop experimental platform was established and further used for online verification under UDDS conditions at 0 ℃ and 25 ℃. Results showed that the proposed algorithm maintained SOC estimation errors within 1.3% at both the environmental temperatures, and the root mean square error decreased by 46.7% and 51.8% compared with the traditional extreme learning machine, respectively, thereby verifying its feasibility and superiority.

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Research on Active Balancing Method for Battery Pack Based on Improved Buck Converter

SHAO Mingxi, ZHANG Hao, CHEN Xiang, YAN Shaojiu, WANG Xiaojuan, ZHANG Wei

Journal of Power Supply. 2025, 23(8): 254-261. https://doi.org/10.13234/j.issn.2095-2805.2025.8.254

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The balancing technology is important for battery management systems. However, the widely used passive balancing technology has disadvantages such as a low efficiency and a long balancing time, while the active balancing technology which is more efficient has problems such as complex control and high cost. In response to the status quo, a double-layer balancing topology circuit based on an improved Buck converter is proposed. Its circuit parameters and balancing strategy are designed by taking into account the issue of matching, its working principle is analyzed in detail, and its economic cost is compared and analyzed, so as to verify the feasibility and economy of the proposed scheme. The simulation analysis of a model based on MATLAB/Simulink shows that the balancing time of the proposed scheme is reduced by 40.4% compared with that of the traditional adjacent cell balancing system. The results of a battery pack balancing test show that this scheme has advantages of a simple structure and simple control. It can quickly realize the balancing of 26650 lithium iron phosphate battery, and it only took 20.4 min to reduce the maximum differential voltage of four battery packs in series from 141 mV to within 50 mV.

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Remaining Useful Life Prediction of Lithium Battery Based on Signal Secondary Decomposition Combined with Machine Learning

DAI Jiajun, LIU Yunbing, CHEN Guici, WANG Wenbo

Journal of Power Supply. 2025, 23(8): 262-272. https://doi.org/10.13234/j.issn.2095-2805.2025.8.262

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The remaining useful life can monitor the instantaneous state of the performance and safety of lithium battery. Therefore, controlling the remaining useful life of lithium battery is of significance for the safety of battery use. In response to the low predictability of high-frequency oscillation components in the initial decomposition of lithium battery capacity, a nonlinear and non-stationary signal processing method based on the secondary decomposition of high-frequency signals combined with machine learning prediction models is proposed. First, the original signal is decomposed by the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) algorithm. Then, the high-frequency random disturbance signals are further decomposed using the variational mode decomposition algorithm, followed by the prediction of components using the long short-term memory (LSTM) network. Experimental verification based on four NASA datasets shows that the proposed method has high prediction accuracy. Compared with those obtained by the CEEMDAN-LSTM model for single decomposition prediction, the value of R² of the sequence prediction is improved by 1.25%, while the values of MAE, RMSE and MAPE are reduced by 39.34%, 49.43% and 41.44%, respectively. The proposed method is robust for the effective prediction of high-frequency signals, as demonstrated by experiments on two CALCE datasets.

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Real-time SOC Estimation of Lithium-ion Batteries Based on Fusion of EKF and Improved DELM

CHEN Xiaofei, JIANG Shuxia, CUI Xiangbo, ZHAO Wenzhuo, WANG Sisi

Journal of Power Supply. 2025, 23(8): 273-283. https://doi.org/10.13234/j.issn.2095-2805.2025.8.273

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Aimed at the poor estimation performance of single algorithms in estimating the state-of-charge (SOC) of lithium-ion batteries, a hybrid algorithm which combines the advantages of deep extreme learning machine optimized by the aquila optimizer (AO-DELM) and the extended Kalman filter (EKF) algorithm is proposed for the SOC estimation of lithium-ion batteries. First, the recursive least squares method with forgetting factor is used to identify the parameters of the battery model. Then, based on the data under a high acceleration cycle(US06) condition, the AO-DELM is trained using the current, voltage and various battery state features extracted by the EKF algorithm as input and the actual SOC as output. Finally, the trained AO-DELM model and the EKF algorithm are used to form a closed-loop real-time SOC estimation system. Resultsshow that compared with the EKF and DELM-EKF algorithms, the proposed AO-DELM-EKF algorithm significantly improves the SOC estimation accuracy under four dynamic conditions, with the root mean square error not more than 0.49%.

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DC Microgrid Energy Management Strategy Based on Hybrid Energy Storage State-of-charge Monitoring

ZHANG Shuai, ZHANG Jihong, WANG Qingyu, WU Zhenkui, ZHANG Zilei

Journal of Power Supply. 2025, 23(8): 284-292. https://doi.org/10.13234/j.issn.2095-2805.2025.8.284

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Aimed at the shortcomings of one single energy storage system in terms of power and energy demand, as well as the problems of low management efficiency and poor economy, the impact of energy storage filtering time constant on the working efficiency is analyzed, with a focus on the traditional hybrid energy storage crossover control method. In addition, a multi-mode coordinated control strategy based on the monitoring of state-of-charge (SOC) is put forward. By dynamically adjusting the filtering time constant and dividing the energy storage into different working areas, the flexibility of energy storage power allocation in DC microgrids is realized to improve the working efficiency. At the same time, according to the source-charge power difference and the SOC of energy storage, four operation modes are designed to optimize the source-charge-storage coordinated control strategy, so as to reduce the number of battery charging and discharging times and improve the system economy. The results of actual microgrid tests show that the proposed control strategy has a higher efficiency and better economy, indicating its value for engineering popular- ization and application.

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Prediction of SOH and RUL for Lithium-ion Batteries Using EIS Data Augmentation Based on VAE Model

CHANG Wei, HU Zhichao, PAN Duozhao, SHI Jiwen

Journal of Power Supply. 2025, 23(8): 293-301. https://doi.org/10.13234/j.issn.2095-2805.2025.8.293

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The state-of-health (SOH) and remaining useful life (RUL) of batteries are important indicators for measuring their performance and conditions, and an accurate prediction of these indicators has high practical value. The electrochemical impedance spectroscopy (EIS) test of batteries can reveal the electrochemical reactions and processes inside them, providing important information for evaluating their SOH. EIS can be used to predict SOH and RUL, but it has high testing costs and limited data volume. The use of variational autoencoder (VAE) for data augmentation can expand the volume of EIS data, which helps improve the model’s generalization capability and reduce the risk of overfitting. Due to the fact that the EIS data is usually high-dimensional and may contain redundant information, principal component analysis (PCA) can be used to reduce the dimensionality of data while retaining the key information. Convolutional neural network (CNN) can recognize the spatial features in the EIS data, while bidirectional long short-term memory (BiLSTM) network can capture features within the time series data. The Attention mechanism can enhance the model’s understanding of data contextual relationships. The research results indicate that the model combining PCA, CNN, BiLSTM network and Attention mechanism can more effectively predict the SOH and RUL of batteries with the addition of augmented data. The proposed EIS data augmentation method can also be applied to other models to improve the predictive performance.

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Study on Hybrid-magnetic-circuit Reactors Based on Magnetic Flux Shunt Principle

MEI Chao, WU Peng, YANG Fuyao, HAN Yu, SU Hailin, ZOU Zhongqiu

Journal of Power Supply. 2025, 23(8): 302-308. https://doi.org/10.13234/j.issn.2095-2805.2025.8.302

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Dry-type core reactors are usually employedas key equipment to achieve reactive compensation in electric power systems on a large scale. However, the vibration noise caused by the magnetostriction effect of core becomes a dominant factor that restrict their applicationsto indoor substations in urban areas. Soft magnetic composites (SMCs) with low magnetostriction and silicon steel were used together as the core material of reactors based on the magnetic flux shunt principle. With the consideration of difference in the efficient permeability between two kinds of materials, the flux in the core is reasonably regulated, so that the larger portion of the flux is carried by the silicon steel component, while the smaller portion flows through the part of SMCs. Based on the design idea, a hybrid- magnetic-circuit (HMC) reactor prototype was designed and fabricated. The research results show that the core losses of HMC reactors were less than those of the pure silicon steel reactor, and thenoise of HMC reactors was less than 60 dB(A), which was lower than that of the silicon steelreactor.

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Accurate Calculation of Winding Losses of Circular Litz-wire in Transformer with CLLC Circuit

ZHOU Lebao, YANG Ru, YANG Hong, LIAO Hui

Journal of Power Supply. 2025, 23(8): 309-316. https://doi.org/10.13234/j.issn.2095-2805.2025.8.309

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To quickly and accurately calculate the winding losses of Litz-wire in a transformer with a CLLC resonant circuit, the orthogonal relationship between the skin effect and proximity effect is utilized to divide the winding losses into those caused by the skin effect and proximity effect, so that these losses can be calculated separately to avoid errors caused by end effects in the windings. First, the duty cycle is used to calculate the losses caused by the proximity effect. By analyzing the current expressions for the transformer with a CLLC resonant circuit and further combining them with the formulas for losses caused by the skin effect and proximity effect, an empirical formula for calculating the winding losses of the transformer with a CLLC resonant circuit is derived. Finally, a transformer with a CLLC resonant circuit was designed and fabricated, Maxwell simulations and experimental measurements were conducted for validation, and the simulated and measured values were also compared with those calculated by a modified Tourkhani model. Results show that the proposed model can accurately calculate the winding losses of Litz-wire in the CLLC transformer, enabling precise prediction of winding losses of Litz-wire in transformers with CLLC resonant circuits.

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HHT-based Fault Detection Scheme for AC-DC Microgrid

ZHANG Jianwen, BAO Yijiu, ZANG Jiajie, ZHOU Jianqiao, SHI Gang, YANG Xingwu

Journal of Power Supply. 2025, 23(8): 317-328. https://doi.org/10.13234/j.issn.2095-2805.2025.8.317

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The AC-DC microgrid can effectively facilitate the applications of renewable energy sources. However, the strong electrical coupling between the AC and DC sides caused by an interconnected converter complicates the fault characteristics within the system, threatening the system’s safe operation. The traditional fault detection schemes based on the fault characteristics may not have enough sensitivity or rapidity to meet the system’s fault detection and protection requirements. Notably, the system exhibits significant fault characteristics before blocking the interconn- ected converter’s IGBTs in the AC-DC microgrid. Therefore, with the combination of grounding schemes for the system and the AC-DC microgrid’s electrical coupling characteristics, the feasibility of a novel fault detection scheme for the AC-DC microgrid based on the Hilbert-Huang transform (HHT) spectrum and energy amplitude is explored, which is aimed at the AC-DC system’s characteristics during the transient process before blocking the IGBTs under fault. Through simulation verification, it is found that the proposed HHT-based fault detection scheme can realize rapid and accurate identification of fault types for the AC-DC microgrid within 2 ms, which effectively improves the safety and reliability of the microgrid.

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Joint Diagnosis Method for IGBT Open-circuit Fault and Voltage Sensor Fault in MMC Submodule

LIU Jingwei, MA Jianjun, CHEN Yang, ZHU Miao, WEN Shuli

Journal of Power Supply. 2025, 23(8): 329-341. https://doi.org/10.13234/j.issn.2095-2805.2025.8.329

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In a modular multilevel converter (MMC) system, there are numerous submodules, and switch faults and voltage sensor faults occur frequently. Some of these faults share similar characteristics, which can affect the system’s operation reliability. A joint diagnosis method for submodule IGBT open-circuit faults and voltage sensor faults based on a sliding mode observer is proposed. First, a fault detection strategy is designed using the actual and measured values of the MMC system’s arm voltage to detect faults in the MMC system and further achieve fault localization at the arm level. On this basis, the sliding mode observer is used to perform online estimation of the capacitor voltage within the faulted arm submodule, and the estimated values are compared with the measured values for submodule-level fault localization. Finally, simulation results verify the effectiveness and robustness of the proposed fault diagnosis algorithm.

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30 December 2025, Volume 23 Issue 8