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Overview of Micro-gas Turbines in Electrified Transportation and Their Electric Energy Conversion Technology XU He, BAO Xianzhe, WANG Lianjie, LI Chushan, LI Wuhua, ZHAO Menglian Journal of Electrical Engineering    2022, 17 (2): 2-18.   DOI: 10.11985/2022.02.002 Abstract （611）   HTML （36）    PDF （698KB）（1085）       Knowledge map    With the proposal of the “Dual-Carbon Goal” and the continuous growth of demand for energy conservation and emission reduction, heavy-duty vehicles represented by commercial vehicles and military vehicles are also gradually moving towards electrification. However, lithium batteries and diesel generators, which are widely used in conventional vehicles, generally have problems such as low energy density and poor power supply quality, which cannot meet the long-range, high-mobility, and low-noise requirements of the new generation of heavy-duty vehicles. Micro gas turbine systems have received extensive attention and rapid development due to their multi-fuel adaptation, low fuel consumption, low noise, low emissions, and low vibration, and have been successfully applied in many civil and military electrified transportation fields. Focusing on the background of transportation electrification, this paper introduces the important position of micro gas turbine technology in electrified transportation, and focuses on summarizing the power conversion topology and control technology in micro gas turbines. The challenges and urgent problems to be solved are pointed out, and the effects, advantages and disadvantages of the existing electric energy conversion solutions for micro gas turbine applications are pointed out, and the future development direction is summarized and prospected. Table and Figures | Reference | Related Articles | Metrics

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Design Method of Dual Active Bridge Based on the Optimum Efficiency QUAN Shengming, SU Shu, ZHAO Nan, LI Chi, ZHENG Zedong Journal of Electrical Engineering    2022, 17 (2): 56-64.   DOI: 10.11985/2022.02.007 Abstract （448）   HTML （14）    PDF （706KB）（608）       Knowledge map    As a new way of distributed storage system, V2G can effectively realize load stabilization and regulation of power grid, and is easy to produce huge economic benefits. Dual active bridge converter is an important part for V2G, which has good electrical isolation and power conversion ability. However, V2G needs bidirectional power ability, wide output voltage range and wide power range, which complex the design of dual active bridge converter. In this paper, a design method of dual active bridge based on the optimum efficiency is proposed, which can consider all the parameters, such as frequency, device, power, magnetic component, control method, output voltage range and input-output voltage relationship, and obtain the dual active bridge converter with optimal efficiency. Table and Figures | Reference | Related Articles | Metrics

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Effect Analysis of Recycling and Storage Conditions on Graphite/LiCoO2 Battery Life ZHANG Bozhao, GOU Bin, XU Yanzhang Journal of Electrical Engineering    2022, 17 (2): 38-48.   DOI: 10.11985/2022.02.005 Abstract （429）   HTML （24）    PDF （691KB）（960）       Knowledge map    Lithium-ion batteries are used for energy storage in a wide array of applications, and the effects of battery ageing limit their performance and occur throughout their whole life. On the one hand, the influence of the average SOC and SOC changes(∆SOC) on the available capacity decay of lithium-ion batteries is quantified by analyzing the data of the graphite/LiCoO2 batteries in different state of charge(SOC) ranges, and a cycle aging model is established. On the other hand, by analyzing the test data of different SOC storage states and different storage temperature life of graphite/LiCoO2 batteries, the influence of storage condition changes on the decay process of lithium battery state of health is revealed, and a calendar aging model is established. The analysis results can be applied to the actual battery cycle use and static storage optimization settings. Table and Figures | Reference | Related Articles | Metrics

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Research on Maglev Drive Architecture and Control Based on EtherCAT MA Zhixun, LIU Siming, NIU Haichuan, HAN Yaofei, LIN Guobin Journal of Electrical Engineering    2022, 17 (2): 73-82.   DOI: 10.11985/2022.02.009 Abstract （423）   HTML （6）    PDF （776KB）（595）       Knowledge map    Linear synchronous motor traction technology is utilized in high-speed maglev system. However, the linear synchronous motors in real maglev system is large and costly, which hinders the pre-researches. A novel segmented permanent magnet linear synchronous motor(PMLSM) drive prototype is developed for deploying and verifying maglev linear motion algorithms quickly in a low-cost way. Moreover, an ARM-FPGA based dual-core controller specific to the prototype is designed for separating algorithm deployment from control implementation. Eventually EtherCAT network is introduced into the controller so as to realize the high-precision and low-latency networked control architecture. Both the availability and feasibility are proved by simulation and experiment. In the future, more maglev linear motion algorithms will be developed, deployed and verified using the maglev drive architecture. Table and Figures | Reference | Related Articles | Metrics

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Topology Design and Stability Analysis of Bipolar DC Power System of Electric Unmanned Aerial Vehicle Feeding Mixed Load YUAN Cong, HUANGFU Yigeng, BAI Hao, LIU Yuntian, ZHANG Hongyu Journal of Electrical Engineering    2022, 17 (2): 110-121.   DOI: 10.11985/2022.02.013 Abstract （388）   HTML （10）    PDF （607KB）（558）       Knowledge map    The DC power system of electric unmanned aerial vehicles(UAVs) mainly provides reliable power for airborne equipment such as propulsion motors, environmental control systems, and radar. According to the bus scheme of system, the DC power system can be divided into unipolar architecture and bipolar architecture. To reduce the loss and volume of a motor and increase the fault tolerance of the system, bipolar architecture is widely used in UAVs and planes. However, since renewable energy generation systems such as fuel cells and photovoltaic usually output unipolar DC voltage, a unipolar-to-bipolar conversion interface is needed to realize unipolar-to-bipolar conversion. Firstly, two kinds of unipolar-to-bipolar conversion interfaces, namely voltage balancer and multilevel converter, are compared and analysed in terms of inductance current ripple, capacitor voltage ripple, and switch stress. Then, based on the comparison results, the multilevel converter is selected as the unipolar-to-bipolar interface, and the bus voltage and neutral-point-voltage controller are designed to realize the voltage and current control, and voltage balance of the bipolar DC power system. Finally, the effects of constant power load, constant current load, and constant resistance load widely existing in the DC system and controller parameters on system stability are analysed. The analysis result is verified by simulation. Table and Figures | Reference | Related Articles | Metrics

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Optimum Total Losses Orientated Modulation Strategy for Dual Active Bridge CHEN Xiaonan, WANG Mingcai, LI Chi, ZHAO Nan, ZHENG Zedong Journal of Electrical Engineering    2022, 17 (2): 49-55.   DOI: 10.11985/2022.02.006 Abstract （388）   HTML （18）    PDF （343KB）（421）       Knowledge map    Dual active bridge converter is widely used in energy storage, traction, DC power transmission due to its good performance in soft-switching, electric isolation and power control ability. Modulation strategy, which decides the current in primary /secondary side and the switching time of the switches, is important for dual active bridge and has great influence on efficiency. The power loss of switches can be calculated under certain modulation strategy. In this paper, an optimum efficiency orientated modulation strategy is proposed. The conduct loss and switching loss are both considered based on the different working mode of dual active converter, and the modulation with lowest total losses and best efficiency can be chosen. The PLECS simulation results show the correctness and effectiveness of proposed strategy. Table and Figures | Reference | Related Articles | Metrics

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Topology and Characteristic Analysis of HVDC Axial Hybrid Excitation Doubly Salient Machine MA Xinchen, CHEN Zhihui Journal of Electrical Engineering    2022, 17 (2): 65-72.   DOI: 10.11985/2022.02.008 Abstract （388）   HTML （3）    PDF （494KB）（704）       Knowledge map    The 270 V high voltage DC(HVDC) system is one of the important development directions of modern aircraft power system. According to the requirements of self-starting and short-circuit current limiting capabilities of high-voltage DC generator, an axial hybrid excitation doubly salient machine(AHEDSM) is proposed. Based on the description of the basic structure and working principle, the variation law of air gap magnetic field with excitation current is obtained by magnetic circuit analysis, which is verified by finite element simulation. The magnetic field distribution, flux linkage, back EMF, output voltage and load characteristics of the machine are analyzed in detail. The results show that the AHEDSM has bipolar variation of phase flux linkage, high sinusoidal degree and wide field regulation range, which can realize complete demagnetization. At the same time, the machine has high efficiency and is suitable for aviation high-speed operation. Table and Figures | Reference | Related Articles | Metrics

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Research on Current Loop Stability of Metro Permanent Magnet Traction System MU Junwen, GE Xinglai, ZHU Dan Journal of Electrical Engineering    2022, 17 (2): 92-100.   DOI: 10.11985/2022.02.011 Abstract （388）   HTML （8）    PDF （676KB）（442）       Knowledge map    In the context of metro permanent magnet traction system applications, the current control loop is prone to instability. Firstly, the current loop closed-loop transfer function of PMSM based on complex vector current controller is derived, and its decoupling performance under variable speed condition is discussed. Secondly, the influences of time delay and angle delay on the stability of the control system are analyzed according to the zero-pole diagram of the current-loop transfer function, and the stability boundary conditions are derived considering the digital control delay comprehensively. Then, the mechanical motion equation of permanent magnet synchronous motor is linearized, the closed-loop transfer function of the system is derived, the zero-pole diagram is drawn, and the stability boundary conditions under different working conditions are analyzed. Finally, experiments verify the correctness of the theoretical analysis. Table and Figures | Reference | Related Articles | Metrics

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Study on Characteristic Parameters of IGBT Module Life of Qinghai-Tibet Bus Auxiliary Inverter XIANG Chaoqun, YIN Xueyao, CHENG Shu, YU Tianjian, ZHANG Lulin Journal of Electrical Engineering    2022, 17 (2): 27-37.   DOI: 10.11985/2022.02.004 Abstract （379）   HTML （7）    PDF （672KB）（788）       Knowledge map    The auxiliary inverter is widely used in the field of rail transit, and the insulated gate bipolar transistor(IGBT), as the common choice of its power electronics, has become the focus of the research of the auxiliary inverter. According to the performance characteristics of IGBT module components of Qinghai-Tibet bus auxiliary inverter power supply, the method of power cycle test is used to grasp the change law of its performance with running time/mileage, and estimate its reliability after long-term service. At the same time, this method can also be used to research the full life cycle performance of the IGBT module in extreme environments, and to provide a reference for the IGBT module’s remaining life evaluation. The results show that the aging life of IGBT modules in extreme environment can be predicted from the changes of two deterioration parameters, threshold voltage and thermal resistance. The relative change of threshold voltage depends on the type and connection mode of multiple chips in parallel, and the thermal resistance increases step by step with aging. Table and Figures | Reference | Related Articles | Metrics

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Study on the Influence Law of Electric Vehicle on Low Frequency Oscillation of Vehicle-network System under Operating Condition MENG Zhaofei, HU Haitao, ZHOU Yi Journal of Electrical Engineering    2022, 17 (2): 131-141.   DOI: 10.11985/2022.02.015 Abstract （368）   HTML （5）    PDF （768KB）（570）       Knowledge map    In recent years, with the large number of new AC-DC transmission EMU and electric train put into operation in China, the phenomenon of low-frequency oscillation appeared in electrified railway, which has caused great harm to the railway system. At present, when studying the low-frequency oscillation of the vehicle-network system, only the influence of the prepared vehicle is considered. However, under the same power supply arm, there are usually running vehicle with high power. Therefore, the difference of the impedance characteristics of the vehicle under different power is analyzed by establishing the impedance model of the prepared vehicle(low power operation) and the high-power running vehicle, and the influence law of the high-power running vehicle on the low-frequency oscillation of the vehicle-network system is analyzed by using the impedance ratio criterion. Finally, the simulation model of traction network, prepared vehicle and the high-power running vehicle is built to verify the correctness of theoretical analysis. Table and Figures | Reference | Related Articles | Metrics

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Integrated Scheme of Charging/discharging for Parking Multi Energy Sources Electric Vehicles Based on Wide Voltage-gain Range Bidirectional DC-DC Converters ZHANG Yun, WEI Yihang, LIU Qiangqiang, KONG Zhiguo Journal of Electrical Engineering    2022, 17 (2): 101-109.   DOI: 10.11985/2022.02.012 Abstract （366）   HTML （9）    PDF （870KB）（665）       Knowledge map    In order to solve the problem of low input voltage range and low utilization ratio of vehicle converter and energy management system, an integrated vehicle parking charging and discharging scheme is proposed in this paper. Compared with the conventional electric vehicle charge and discharge technology, this scheme not only realizes the energy interaction between the vehicle hybrid energy sources and the vehicle DC bus and micro-grid, providing the possibilities for peak load shifting for the connected DC micro-grid, but also reduces the charging voltage level of the electric vehicle charger. Last but not least, this scheme also greatly broadens the vehicle power battery charging method and maximizes the utilization of the vehicle converter, vehicle energy management system and power motor. Finally, an experimental platform of 1.2 kW hybrid energy sources charging and discharging system is built, which verifies the rationality and feasibility of the integrated parking charging and discharging scheme, so the scheme proposed in this paper can be further popularized and realized in the field of electric vehicle charge and discharge technology research in the future. Table and Figures | Reference | Related Articles | Metrics

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Calculation of IGBT Junction Temperature with Thermal Network Model Considering Flow-thermal Coupling XU Zhiliang, GE Xinglai, LI Jin, KE Qianxia, ZHU Dan Journal of Electrical Engineering    2022, 17 (2): 19-26.   DOI: 10.11985/2022.02.003 Abstract （361）   HTML （17）    PDF （637KB）（699）       Knowledge map    The junction temperature calculation of insulated gate bipolar transistor(IGBT) is of great significance for evaluating its remaining life and ensuring the reliable operation of power electronic converters. The traditional thermal network method ignores the real heat transfer process between the module and the radiator, and it is difficult to calculate the junction temperature change accurately and effectively. To address this, a calculation method of IGBT junction temperature with thermal network model considering flow-thermal coupling is proposed. In this method, the thermal network model of IGBT module and the radiator is extracted by the finite element simulation considering the flow-thermal coupling, and the junction temperature of the IGBT is calculated based on the easily obtained radiator water temperature as the temperature reference point. In order to verify the validity of the model, a power cycle accelerated aging test platform is built to extract the junction temperature change curve. The results show that the proposed thermal network model can calculate the IGBT junction temperature more realistically and accurately. And it can provide more real and accurate junction temperature change data for the reliability evaluation and remaining life prediction of IGBT modules in practical applications. Table and Figures | Reference | Related Articles | Metrics

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Enhanced Electric Braking Force Scheme of Train Traction System in Low-speed Range LI Jianxin, LI Jiayao, GAO Xiang, JIANG Wei, SONG Wensheng Journal of Electrical Engineering    2022, 17 (2): 83-91.   DOI: 10.11985/2022.02.010 Abstract （323）   HTML （5）    PDF （802KB）（523）       Knowledge map    At present, the electro-pneumatic combined braking method is generally adopted in the traction drive system in China, which has disadvantages such as the passenger’s comfort decline caused by the switching of electric braking and pneumatic braking at low speed, weak controllability of pneumatic braking and serious wear of brake shoes. In order to solve this problem, an electric braking control technology of the train based on regenerative braking and plug braking is proposed, which can realize the electric braking in the whole speed range. Firstly, according to the relationship between torque and slip frequency under vector control, the torque output capacity of different braking methods at low speed is analyzed. The controllability of braking torque of regenerative braking when stator frequency is greater than zero and plug braking when stator frequency is less than zero is determined. Secondly, through the field orientation of indirect vector control and the flux observation of direct vector control, the realization principle and feasibility of plug braking are proved. Furthermore, a pure electric braking scheme in which regenerative braking is naturally commutated to plug braking in the low-speed range is proposed. Finally, a low power motor towing experiment test is carried out, the experimental results verify that the proposed braking strategy can achieve stable and controllable output of braking torque in low-speed range and the torque is smooth without impact, which improves the electric braking ability of the train in low-speed range. Table and Figures | Reference | Related Articles | Metrics

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Short Circuit Steady State Calculation and Protection Analysis Based on Hybrid Traction Power Supply System CHENG Shu, ZHOU Tianjiao, XIANG Chaoqun Journal of Electrical Engineering    2022, 17 (2): 122-130.   DOI: 10.11985/2022.02.014 Abstract （302）   HTML （6）    PDF （612KB）（529）       Knowledge map    For the hybrid traction power supply system with parallel coupling of 24 pulse rectifier unit and inverter energy feed device, the current characteristics of DC side short-circuit fault are studied, and the corresponding DC side short-circuit protection setting parameters are formulated. First, the equivalent parameters of rectifier unit and energy feed device are calculated, and the DC side short-circuit characteristics of hybrid traction power supply system are studied according to the superposition theorem. Then the relay protection types and protection setting design principles of traction power supply system are introduced and analyzed. The simulation model of hybrid traction power supply system with inverter energy feed device is built to simulate the short circuit at the near and far ends of DC side of DC traction power supply system with inverter energy feed device, and the equivalent calculation results are verified. The protection setting parameters of the hybrid traction power supply system are set according to the simulated current waveform, and the protection types enabled at different short-circuit distances are judged. It is determined that the hybrid traction power supply system can cut off the circuit correctly to ensure the safe operation of urban rail transit system. Table and Figures | Reference | Related Articles | Metrics

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Journal of Electrical Engineering    2022, 17 (2): 1-1.   DOI: 10.11985/2022.02.001 Abstract （160）   HTML （21）    PDF （123KB）（165）       Knowledge map    Reference | Related Articles | Metrics