30 results on '"Sun, Pengju"'
Search Results
2. Evaluation of Urban Transportation Resilience under Extreme Weather Events.
- Author
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Cui, Yuepeng, Liu, Zijian, Wu, Huiming, Sun, Pengju, and Zhou, Fubin
- Subjects
EXTREME weather ,URBAN transportation ,RAINSTORMS ,EMERGENCY management ,GEOGRAPHIC boundaries ,EWES ,BUS transportation - Abstract
The frequent occurrence of extreme weather events (EWEs) in recent years has posed major hazards to urban transportation as well as socioeconomic impacts. A quantitative evaluation of the urban transportation resilience to minimize the impact caused by EWEs becomes critical to the rapid recovery of urban transportation after disasters. However, there is, generally, a lack of reliable data sources to monitor urban transportation performance under EWEs. This empirical study proposes a performance indicator (displacement) and quantitative method for evaluating the urban transportation performance under EWEs based on bus GPS trajectory datasets. Furthermore, the transportation resilience of it is quantified, and the variation is compared across temporal and spatial dimensions. The method is applied in a case study of Fuzhou, China, under rainstorm events. The results show that the Gulou and Jinan subareas have the highest transportation resilience during the yellow and red rainstorm warnings. By formulating an emergency plan and taking mitigation measures, the transportation performance in the Jinan subarea during the red rainstorm warning was improved by 36% compared to the yellow rainstorm warning. The empirical study not only fills the knowledge gap for quantifying the transportation resilience across the geographical boundary under rainstorm events, but also estimates the operation status of the road network. The results will help policymakers prioritize the resource distribution and develop effective policies or measures to further improve transportation resilience in the city. [ABSTRACT FROM AUTHOR]
- Published
- 2024
- Full Text
- View/download PDF
3. rTMS treatment for abrogating intracerebral hemorrhage‐induced brain parenchymal metabolite clearance dysfunction in male mice by regulating intracranial lymphatic drainage.
- Author
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Liu, Yuheng, Liu, Xuanhui, Sun, Pengju, Li, Jing, Nie, Meng, Gong, Junjie, He, Anqi, Zhao, Mingyu, Yang, Chen, and Wang, Zengguang
- Published
- 2023
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4. A Bridge-Level Junction Temperature Estimation Method for SiC MOSFETs Combining Transient Voltage and Current Peaks.
- Author
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Wu, Shuo, Sun, Pengju, Huang, Xu, and Li, Kaiwei
- Subjects
- *
METAL oxide semiconductor field-effect transistors , *FIELD-effect transistors , *IMPACT loads , *VOLTAGE , *ELECTRIC potential measurement , *TEMPERATURE - Abstract
Accurate measurement of the junction temperature Tj is crucial for ensuring safe operation and evaluating the performance of silicon carbide (SiC) metal–oxide–semiconductor field-effect transistors (MOSFETs). In this paper, the junction temperature of a half-bridge is monitored by combining transient voltage and current peaks across the lower device. Both theoretical analysis and switch tests validate that the peak induced voltage and peak reversed current during the commutation transient exhibit a linear relationship with the temperature of the corresponding devices. The impact of load current and bus voltage on the measurement results is also investigated. Moreover, the effectiveness of the proposed method is confirmed by carrying out tests at different temperatures, and the feasibility of online implementation is discussed. The experimental results show that the proposed method has high linearity and sensitivity and can simultaneously provide temperature information for both devices of a half-bridge. [ABSTRACT FROM AUTHOR]
- Published
- 2023
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5. Quantile Regression Learning with Coefficient Dependent lq-Regularizer
- Author
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Sun Pengju, Li Meng, and Sun Hongwei
- Subjects
Engineering (General). Civil engineering (General) ,TA1-2040 - Abstract
In this paper, We focus on conditional quantile regression learning algorithms based on the pinball loss and lq-regularizer with 1≤q≤2. Our main goal is to study the consistency of this kind of regularized quantile regression learning. With concentration inequality and operator decomposition techniques, we obtained satisfied error bounds and convergence rates.
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- 2018
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6. Systematic Overview of Active Battery Equalization Structures: Mathematical Modeling and Performance Evaluation.
- Author
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Qu, Fan, Luo, Quanming, Liang, Huan, Mou, Di, Sun, Pengju, and Du, Xiong
- Subjects
MATHEMATICAL models ,LITHIUM-ion batteries ,COST structure ,BATTERY storage plants ,ELECTRIC batteries ,QUANTITATIVE research - Abstract
With the widespread application of lithium-ion battery packs, it calls for efficient balancing methods to improve the performance of these battery systems. The relevant research has focused on the design of equalization circuits and control strategies while neglecting quantitative analysis and comparison of battery active equalization structures from the systematic level. In this paper, we propose an improved system-theoretic modeling approach for active equalization structures that takes into account the battery's constraints, including equalization current rate and SOC operation range. Accordingly, the mathematical models of various active equalization structures are derived that can describe their equalization dynamic behavior. Then, the analytical algorithms are developed to estimate the balancing time of active equalization structures online. Finally, extensive numerical simulations are conducted to evaluate and compare the average performance of these equalization systems in term of equalization time. It then comes up with a comprehensive comparison among them. Consequently, the Multicell-to-Multicell (MC2MC) balancing structure benefits the fast balancing speed and the lowest sensitive to initial batteries’ SOCs. The global structure has the lowest implementation cost and the series structure benefits the simplest control. Moreover, the module-based structures have faster balancing speed when each module contains about 4–6 batteries. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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7. Large-Signal Stability Analysis of DC Side of VSC-HVDC System Based on Estimation of Domain of Attraction.
- Author
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Zheng, Huajun, Yuan, Xufeng, Cai, Jie, Sun, Pengju, and Zhou, Luowei
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LYAPUNOV stability ,TEST systems ,PROBLEM solving ,STABILITY criterion ,LARGE deviations (Mathematics) - Abstract
The existing research on voltage-source converter HVDC (VSC-HVDC) system stability mostly focuses on small-signal stability analysis methods. However, when large-signal disturbances occur, the intrinsic nonlinearity of the VSC-HVDC system becomes inevitable so that the small-signal studies are no longer valid. In this paper, a large-signal stability analysis method of the VSC-HVDC system is proposed based on the estimation of domain of attraction (DOA). This method can not only analyze the asymptotic stability of the operating point, but also answer the question of how large deviations from the operating point can be tolerated by the system. By using Takagi-Sugeno (T-S) fuzzy model and Lyapunov stability theorem, the DOA of the VSC-HVDC System at the operating point is estimated, and the large-signal stability of VSC-HVDC System is analyzed. On this foundation, the influence of system parameters on the large-signal stability is studied. The results can be used to guide the adjustment of system parameters to solve the problem of system instability. The time-domain simulations conducted in Matlab/Simulink are used to test the stability of the system under large-signal disturbance in the range of DOA. The simulation results verify the feasibility and effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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8. A Fast Short-Circuit Protection Method for SiC MOSFET Based on Indirect Power Dissipation Level.
- Author
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Ouyang, Wenyuan, Sun, Pengju, Xie, Minghang, Luo, Quanming, and Du, Xiong
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FIELD-effect transistors , *METAL oxide semiconductor field-effect transistors , *SHORT circuits , *SILICON carbide , *ELECTRIC inductance , *SEMICONDUCTORS - Abstract
This letter proposes an indirect power dissipation level short circuit protection (IPDL-SCP) method for silicon carbide (SiC) metal-oxide semiconductor field-effect transistors (mosfets). Due to differences between normal conducting and short-circuit (SC) conditions, this method is triggered by the voltage oscillation vss at the parasitic inductance (Lss) of the source and directly monitoring vds of SiC mosfet. For verification, the short circuit protection circuit is tested and proved functional on the SC test bench. Experimental results show that the protection circuit can respond to both hard switching fault (HSF) and fault under load (FUL), while the fastest response delays are 75 ns for HSF and 170 ns for FUL. Comparisons with other commonly used SC protection methods have also been made, which show that the proposed IPDL-SCP method has better performance in shorter protection delays. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
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9. Online Gate-Oxide Degradation Monitoring of Planar SiC MOSFETs Based on Gate Charge Time.
- Author
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Xie, Minghang, Sun, Pengju, Wang, Kaihong, Luo, Quanming, and Du, Xiong
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METAL oxide semiconductor field-effect transistors , *SILICON carbide , *TRANSISTORS , *ELECTRIC capacity , *LOGIC circuits - Abstract
Gate-oxide degradation has been one of the critical reliability concerns of silicon carbide (SiC) metal–oxide–semiconductor-field-effect transistors (mosfets), which could be monitored through aging-sensitive parameters. In this article, an online gate-oxide degradation monitoring method for planar SiC mosfets is proposed by extracting gate charge time at a specific range of gate voltage. It is based on the findings that the input capacitances of planar SiC mosfets change significantly over gate-oxide degradation, which is theoretically analyzed and experimentally verified. The capacitance variations are converted into the gate charge time as the new aging-sensitive parameter. The new parameter measurement circuit is proposed and integrated into the gate driver module. The article results indicate that the new parameter varies noticeably with gate-oxide degradation and the difference of this parameter caused by junction temperature is much smaller than that caused by degradation. Besides, the parameter is immune to package degradation and load current. The condition monitoring method can be implemented online since the parameter is extracted during the off-state of SiC mosfet devices, which does not affect normal operation. The confirmatory experiment is carried out to verify the correctness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2022
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10. A Hybrid Five-Variable Modulation Scheme for Dual-Active-Bridge Converter With Minimal RMS Current.
- Author
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Li, Jia, Luo, Quanming, Mou, Di, Wei, Yuqi, Sun, Pengju, and Du, Xiong
- Subjects
PARTICLE swarm optimization ,ROOT-mean-squares ,MATHEMATICAL optimization ,HARMONIC analysis (Mathematics) ,PHASE modulation ,ZERO voltage switching - Abstract
In order to further improve the efficiency of dual-active-bridge (DAB) converter, a hybrid five-variable modulation scheme with minimal root mean square (rms) current is proposed in this article, which combines the traditional phase-shift and pulsewidth modulation schemes. By adopting the proposed optimal scheme, a wider zero-voltage switching (ZVS) operation range and lower rms current level are achieved simultaneously when compared with other modulation schemes, which significantly improves the efficiency of the DAB converter. Moreover, for the complexity of the proposed modulation scheme with five variables, the Fourier decomposition based analytical expressions are derived for the converter and a generalized performance analysis results are presented. Besides, in order to avoid the analysis error, especially at light-load condition, the optimization strategy takes the rms current as the optimal objective, which includes the eight harmonic component of the inductor current rather than just considers the fundamental component. And an offline particle swarm optimization algorithm is introduced to acquire the optimal operating points for the whole power range. To substantiate the effectiveness of the proposed modulation scheme, a comprehensive comparison among related works in terms of the rms value and ZVS range were carried out under various operation condition. Finally, a 1.2 kW experimental platform was built and the highest experimental efficiency under the proposed modulation scheme reaches 96.8%. [ABSTRACT FROM AUTHOR]
- Published
- 2022
- Full Text
- View/download PDF
11. A Variable Inductor Controlled Single-Stage AC/DC Converter for Modular Multi-Channel LED Driver.
- Author
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He, Qingqing, Luo, Quanming, Wei, Yuqi, and Sun, Pengju
- Subjects
LIQUID crystal displays ,ELECTRIC current rectifiers ,MULTICHANNEL communication ,STREET lighting ,ZERO voltage switching ,LIGHT emitting diodes ,COST control - Abstract
Light-emitting diodes (LEDs) are widely used in street lighting, landscape lighting, liquid crystal display (LCD) backlighting, healthcare, etc. As an important part of LED lighting products, LED driver plays a vital role in maintenance costs reduction, energy saving and lifetime prolongation. In this paper, a single-stage LED driver is proposed, which is integrated by a totem-pole bridgeless power factor correction (PFC) unit and several modular LCL-T resonant rectifiers. The totem-pole bridgeless PFC unit and the LCL-T resonant rectifiers are integrated by sharing switches, which can simplify the circuit and reduce the system cost. The output current can be regulated by applying the variable inductor control. Constant duty cycle and fixed switching frequency operation can be achieved as well. The operating principle and the performance of the proposed converter are analyzed in this paper. In addition, a precise parameter design method is proposed by considering the high-order harmonics. At last, an experimental prototype is established to validate the proposed parameter design and variable inductor control method. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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12. Online Condition Monitoring for Bond Wire Degradation of IGBT Modules in Three-Level Neutral-Point-Clamped Converters.
- Author
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Wang, Xulong, Sun, Pengju, Sun, Lin, Luo, Quanming, and Du, Xiong
- Subjects
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INSULATED gate bipolar transistors , *ELECTRIC current rectifiers , *MODULAR coordination (Architecture) - Abstract
In this article, an online condition monitoring (CM) method is proposed for the bond wire degradation of insulated-gate bipolar transistor (IGBT) modules in a single-phase or three-phase three-level neutral-point-clamped (3LNPC) dc–ac, ac–dc converter. The proposed method has the ability to detect the whole IGBTs in a 3LNPC converter, based on finding the idle on-state IGBTs under the specific load current direction and switching sequence of a leg. The detection time is short (0.2 ms) and the influence of online CM on load current can be completely neglected as long as the insertion areas for CM test are chosen reasonably. Meanwhile, an advanced bond wire CM module is designed to conduct the CM test. This module can generate and inject the current pulse trains into IGBT modules, with the high current for CM test and low current for temperature-sensitive electrical parameter measurement, and sample the collector–emitter on-state voltage (VCE ON) stably and precisely. Finally, the experimental work was carried out to verify the effectiveness of the proposed method and the practicality of the developed CM module. [ABSTRACT FROM AUTHOR]
- Published
- 2021
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13. Hybrid Duty Modulation for Dual Active Bridge Converter to Minimize RMS Current and Extend Soft-Switching Range Using the Frequency Domain Analysis.
- Author
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Mou, Di, Luo, Quanming, Li, Jia, Wei, Yuqi, Wang, Zhiqing, Sun, Pengju, Du, Xiong, and Mantooth, H. Alan
- Subjects
ROOT-mean-squares ,PHASE modulation ,FREQUENCY-domain analysis ,ZERO voltage switching ,SOFT sets ,BRIDGE circuits - Abstract
In this article, an efficiency-oriented hybrid duty modulation (HDM) scheme is proposed for the dual active bridge (DAB) converter that can reduce the inductor root-mean-square (rms) current and extend the switch soft-switching range. First, a complete description of the combination forms of different modulation schemes is presented considering the allocation of the zero-voltage portion. A unified description for these combination forms is obtained in the frequency domain. Second, the symmetric–symmetric duty modulation (SSDM) scheme and asymmetric–symmetric duty modulation (A2SDM) scheme are established to minimize the inductor rms current by considering its fundamental component. Third, the characteristics of SSDM, A2SDM, and the traditional phase shift modulation schemes are compared from several aspects, mainly including the inductor rms current and the soft-switching performance. Furthermore, the loss breakdown analysis results for the three modulation schemes are presented and compared. According to these results, the HDM scheme is proposed to improve the overall efficiency of the DAB converter. Finally, an experimental prototype was built with a peak efficiency of 97%, which validates the effectiveness of the proposed modulation scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
14. Monitoring Bond Wires Fatigue of Multichip IGBT Module Using Time Duration of the Gate Charge.
- Author
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Wang, Kaihong, Zhou, Luowei, Sun, Pengju, and Du, Xiong
- Subjects
INSULATED gate bipolar transistors ,CONSTANT current sources ,TIME management - Abstract
Monitoring the defective multichip insulated gate bipolar transistor (IGBT) module is a cost-effective approach to improve the quality of customer service. A method using time duration of the gate charge is proposed to monitor bond wires fatigue of the multichip IGBT modules when the modules are in the off-state. It is based on the fact that failure of the chip branch due to bond wires fatigue changes the gate input capacitance of the multichip IGBT module. The health state of bond wires can be converted into the change of time duration of gate charge under the constant gate current. A driver containing the constant current source is proposed. The study results indicate that the time duration of the gate charge decreases significantly when the failure of the chip branch occurs, and the effect of junction temperature can be ignored within the special range of gate voltage. Condition monitoring can be implemented during the off-state of the multichip module and without considering the effects of junction temperature. The confirmatory experiment is carried out to verify the correctness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
15. Feedforward phase compensation method of LCL grid‐connected inverter based on all‐pass filter in weak grid.
- Author
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Xue, Tongyu, Sun, Pengju, Xu, Zezhong, and Luo, Quanming
- Abstract
Inverter‐side current feedback control (ICFC) has been extensively adopted in distributed generation systems because of its simple implementation and better consistency with actual operating conditions. At the same time, when there are a large number of background harmonics in the grid, capacitor voltage feedforward (CVF) is usually added to the system for its suppression. This method could make the system keep the first‐order characteristics under the analogue control. However, under digital control, due to the digital control delay, a reverse resonance peak will be generated in the loop gain, which makes the system unstable in the weak grid. In order to solve the aforementioned problems, this study proposes a feedforward phase compensation method of LCL grid‐connected inverter based on the all‐pass filter (AF). By introducing AF into the CVF channel, the phase lag in the range of reverse resonance peak frequency is compensated, so as to enhance the robustness of the system in the weak grid. At the same time, this study gives the detailed design process of the proposed method. Experimental results on a 3‐kW prototype are provided, and the effectiveness of the proposed control method is verified.. [ABSTRACT FROM AUTHOR]
- Published
- 2020
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- View/download PDF
16. A Review of Switching Oscillations of Wide Bandgap Semiconductor Devices.
- Author
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Chen, Jian, Du, Xiong, Luo, Quanming, Zhang, Xinyue, Sun, Pengju, and Zhou, Lin
- Subjects
WIDE gap semiconductors ,METAL oxide semiconductor field-effect transistors ,SEMICONDUCTOR devices ,OSCILLATIONS ,GALLIUM nitride ,FIELD-effect transistors - Abstract
Wide bandgap (WBG) devices offer the advantages of high frequency, high efficiency, and high power density to power converters due to their excellent performance. However, their low parasitic capacitance and fast switching speed also make them more susceptible to switching oscillations. The switching oscillations can cause voltage and current overshoots, shoot-through, electromagnetic interference, additional power loss, and even device damage, which can seriously affect the performance of power converters and systems. However, a comprehensive and in-depth overview is lacking on this topic. This article reviews the types, the causes and negative effects, the effects of parasitic parameters and suppression methods of these switching oscillations, which is helpful for practical engineering. First, the switching oscillations are divided into different types, and their causes and negative effects are reviewed. Then, the effects of different parasitic parameters on the switching oscillations are overviewed. It is found that due to the different physical structures of silicon carbide metal-oxide-semiconductor field-effect transistors, enhancement-mode gallium nitride high-electron mobility transistors (eGaN HEMTs), and cascode GaN HEMTs, the effects are also different. Finally, the main methods of suppressing the switching oscillations are summarized, and the advantages and disadvantages of these methods are presented. Furthermore, future research works on this topic and the conclusion of this paper are drawn, which will help readers deepen their understanding of the switching oscillations of WBG devices, and inspire readers to better use WBG devices for high-frequency and high-efficient power conversion. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
17. Topology Analysis and Review of Three-Port DC–DC Converters.
- Author
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Wang, Zhiqing, Luo, Quanming, Wei, Yuqi, Mou, Di, Lu, Xinlei, and Sun, Pengju
- Subjects
DISTRIBUTED power generation ,CASCADE converters ,DC-to-DC converters ,GALVANIC isolation ,PHOTOVOLTAIC power systems ,TOPOLOGY ,POWER transmission - Abstract
In order to realize power flow control among photovoltaic (PV) panel port, battery port, and load port in the distributed photovoltaic power generation system, integrated three-port dc–dc converters (TPCs) are widely adopted. The objective of this article is to provide a comprehensive, comparative, and insightful analysis and overview of these TPCs. First, based on the power transmission and control requirements of the system, five topological structures of three-port dc–dc conversion system (TPCS) composed of two or three two-port dc–dc converters are presented. And the five structures are comparatively analyzed. Second, based on these topological structures, and combing with the basic two-port dc–dc converters, three groups of typical TPCs with different galvanic isolation requirements are derived, respectively, by sharing switches, combining branches, etc., And comprehensive analysis, comparisons, and reviews of these TPCs with different structures of each isolation type are presented with tables and figures. Finally, the comparison results of the three isolation groups are summarized, which leads to a guidance for the selection of TPCs in different applications, and then some suggestions for the future research on TPCs are given. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
18. Frequency-Division Virtual Impedance Shaping Control Method for Grid-Connected Inverters in a Weak and Distorted Grid.
- Author
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Zhu, Kunlong, Sun, Pengju, Zhou, Luowei, Du, Xiong, and Luo, Quanming
- Subjects
- *
IMPEDANCE control , *DYNAMICAL systems , *PULSE width modulation transformers , *PROBLEM solving , *HARMONIC distortion (Physics) , *ELECTRIC potential - Abstract
Grid-connected current quality is seriously affected by the low-order background harmonics in the gird-inverter dynamic system. The point of common coupling voltage feedforward impedance reshaping method of the grid-connected inverter is generally applied to solve this problem, however about 90° phase lag of the inverter output impedance is brought in, which would deteriorate the adaptability of the inverter to the weak grid. To solve this problem, this article proposes a novel frequency-division virtual impedance shaping method, which shapes the output impedance of the grid-connected inverter with different coefficients in different frequency bands, respectively. The basic principles, parameters design, and application analysis are studied in detail. With the proposed scheme, the grid-connected inverter can be equipped with strong adaptability to a wide range of grid impedance and suppression ability to the background voltage harmonics simultaneously. Theoretical analysis and experimental results confirm the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
19. Large-Signal Stability Analysis for VSC-HVDC Systems Based on Mixed Potential Theory.
- Author
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Zheng, Huajun, Zhou, Luowei, Sun, Pengju, and Lu, Weiguo
- Subjects
SYSTEM analysis ,STABILITY criterion ,VOLTAGE control - Abstract
Stability studies of voltage-source converter HVDC (VSC-HVDC) systems are mainly based on small-signal linearization techniques. However, when VSC-HVDC systems become unstable due to large-signal disturbances, the small-signal analysis method would be no longer available. In this paper, the large signal stability of VSC-HVDC system is studied based on mixed potential theory. A simplified state-space averaging model of VSC-HVDC system is established under the synchronous rotating reference frame. Based on this model, the stability prediction criteria for VSC-HVDC system under large-signal disturbances is obtained through Brayton-Moser's nonlinear potential method. On this foundation, the influence of system parameters on the large-signal stability is studied and the boundaries of stability are located as well. Time-domain simulations conducted in Matlab/Simulink are used to test the stability of the working points next to the stable boundary, which aim to prove the correctness of the obtained stability criterion. Aiming at the unstable situation, the time-domain simulation results prove the feasibility of the method of adjusting the system parameters according to the stability criterion to make the system stable, which further verifies the correctness of the stability criterion. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
- View/download PDF
20. Analysis and Design of an RC Snubber Circuit to Suppress False Triggering Oscillation for GaN Devices in Half-Bridge Circuits.
- Author
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Chen, Jian, Luo, Quanming, Huang, Jian, He, Qingqing, Sun, Pengju, and Du, Xiong
- Subjects
RC circuits ,GALLIUM nitride ,PULSE circuits ,ELECTROMAGNETIC interference ,OSCILLATIONS - Abstract
Wide bandgap devices such as gallium nitride (GaN) devices are being widely used due to their low on-resistance and parasitic parameters that can improve system performance compared to Si mosfets. However, these advantages mentioned above can sometimes lead to unexpected behavior in practical systems, such as false triggering oscillation. False triggering oscillation may cause overshoot, electromagnetic interference, shoot-through, and even device damage, which seriously affects the performance of the system. In this paper, an RC snubber circuit is proposed to suppress false triggering oscillation in a half-bridge circuit, and the design method of the RC parameters is proposed. The proposed oscillation suppression method is simpler, easier to implement, and more effective than the active gate driver. In addition, it can provide guidance for oscillation suppression design in high-order systems. First, the double pulse circuit is used as an example to analyze false triggering oscillation and its high-frequency equivalent circuit is obtained. Then, the RC region is established by scrutinizing the characteristic equations via a root locus method. The RC snubber circuit has better oscillation suppression effect when the RC parameters are within the region rather than outside the region. Finally, the RC region designed by the proposed method is verified by simulation and experiment results, and the proposed method indicates a substantial improvement of the switching characteristics of the controlled device at turn-off. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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21. Research on Topology of the High Step-Up Boost Converter With Coupled Inductor.
- Author
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Chen, Si, Zhou, Luowei, Luo, Quanming, Gao, Wei, Wei, Yuqi, Sun, Pengju, and Du, Xiong
- Subjects
ELECTRIC network topology ,TOPOLOGY ,PHOTOVOLTAIC cells ,FUEL cells ,QUANTITATIVE research - Abstract
High step-up boost converters with coupled inductor have attracted much attention in the fuel cell or photovoltaic grid-connected generation system, however, there are few literatures elaborated on the construction ideas and derivation methods of them. Accordingly, in order to obtain a clear roadmap on the derivation and inner connection of these converters, a comprehensive review and analysis are presented in this paper. First, the basic boost converter with coupled inductor is regarded as the basic topology, and its merits and demerits are analyzed in detail. Then, in order to address these demerits, various step-up techniques are introduced, such as the rectifier circuit, the active-clamped circuit, the multi-winding coupled inductor, and the voltage doubler rectifier; and numerous new topologies are continuously proposed by combinations and equivalent simplifications. In addition to a detailed synthesis of each topology, a comparative and quantitative analysis among some important converters is presented, and the optimal one is chosen to build a 250 W prototype. Finally, based on comparisons and analysis, the main characteristics and inner connections of these high step-up boost converters with coupled inductor are identified and clarified. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
22. Analysis and design of the DCM operation boost PFC converter with magnetic control.
- Author
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Yuqi Wei, Quanming Luo, Jie Wang, and Sun Pengju
- Subjects
CORRECTION factors ,AC DC transformers ,DESIGN - Abstract
In this study, a novel control scheme for the discontinuous conduction mode (DCM) operation boost power factor correction (PFC) converter is proposed. Instead of adopting constant duty cycle (CDC) control, variable duty cycle control or frequency control, the magnetic control or variable inductor control is adopted to regulate the output voltage, so CDC and switching frequency can be implemented for the switch. The operation principles of the proposed control scheme are discussed in details, and the analysis of the input current, power factor, boundary condition and design considerations are presented. In addition, the modelling of the variable inductor and the DCM operation boost PFC converter with variable inductor are derived in detail, by linearising the non-linear components, the model of the DCM operation boost PFC converter with the proposed control scheme can be obtained, and the design procedures of the PI controller are presented. Finally, a 70 W experimental prototype is built to verify the theoretical analysis and the effectiveness of the proposed control scheme. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
23. Thermal Parameter Monitoring of IGBT Module Using Case Temperature.
- Author
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Zhang, Jun, Du, Xiong, Wu, Yu, Luo, Quanming, Sun, Pengju, and Tai, Heng-Ming
- Subjects
INSULATED gate bipolar transistors ,THERMAL interface materials ,COOLING curves ,THERMAL resistance ,TEMPERATURE - Abstract
In this paper, we propose to monitor the thermal parameters of insulated gate bipolar transistor (IGBT) module using the case temperature. This method works during the shutoff period of IGBT module where the case temperature is in the cooling phase By establishing the relationship between the Cauer-type thermal RC parameters and the time constants of case temperature cooling curves, thermal parameters of the IGBT module can be identified. The proposed method is able to eliminate the influence of thermal interface material (TIM) degradation on the monitored results, which is quite challenging for the current case temperature monitoring methods. Moreover, it enables the detection of thermal resistance and thermal capacitance of the TIM and that of the IGBT module at the same time. Experimental tests are performed to validate the accuracy and feasibility of the proposed method. Moreover, impacts of the junction temperature, case temperature sensing position, and thermal coupling on the monitored results are analyzed. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
24. Analysis and Design of a Single-Stage Bridgeless High-Frequency Resonant AC/AC Converter.
- Author
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He, Qingqing, Luo, Quanming, Ma, Kun, Sun, Pengju, and Zhou, Luowei
- Subjects
CONVERTERS (Electronics) ,RESONANT states ,ALTERNATING currents ,ELECTRIC currents ,ELECTRIC current rectifiers - Abstract
A single-stage high-frequency resonant ac/ac converter converts the ac-line input voltage into the high-frequency sinusoidal output voltage, which consists of two power conversion units, i.e., a power factor correction (PFC) unit and a high-frequency resonant dc/ac unit, and it can be used to derive a modular multichannel constant current LED driver. By adopting a totem-pole bridgeless PFC boost rectifier to reduce conduction losses, a single-stage bridgeless high-frequency resonant ac/ac converter is proposed in this paper. The operating principle is described, and the performance analysis is presented in detail. Moreover, the quantitative parameter design method of the main circuit is presented, which is suitable for other single-stage ac input converters, such as a single-stage PFC rectifier. Finally, a 130-W prototype has been built and tested to verify the correction of related theoretical analysis and parameter design. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
25. Active Junction Temperature Control of IGBT Based on Adjusting the Turn-off Trajectory.
- Author
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Wang, Bo, Zhou, Luowei, Zhang, Yi, Wang, Kaihong, Du, Xiong, and Sun, Pengju
- Subjects
INSULATED gate bipolar transistors ,TEMPERATURE control ,FLUCTUATIONS (Physics) ,PARAMETER estimation ,PHYSICS experiments - Abstract
The junction temperature fluctuation of an insulated-gate bipolar transistor (IGBT) is the most important factor of its aging failure, and smoothing the fluctuation is an effective way to improve the life of an IGBT. The existing methods for smoothing the fluctuation by active junction temperature control are not yet ready wide application, and exploring the different approaches to active junction temperature control is a hot topic. This paper presents a method of active junction temperature control that shifts the turn-off trajectory of an IGBT to adjust the IGBT turn-off loss for smoothing the junction temperature. The relationship between parameters of the adjusting circuit and turn-off loss is analyzed. On the basis of this analysis, a method of estimating the smoothing ability for the proposed active junction temperature control is deduced. Using an IGBT installed in a 1.2-MW direct-drive wind power converter as an example, the evaluation result shows that the proposed method can completely smooth the junction temperature fluctuation caused by a 40% rated load fluctuation. Finally, a low-power experiment is carried out. [ABSTRACT FROM PUBLISHER]
- Published
- 2018
- Full Text
- View/download PDF
26. Photooxygenations and Self-Sensitizations of Naphthylamines: Efficient Access to Iminoquinones.
- Author
-
Wei, Ying, Tang, Lei, Zhong, Chunxiao, Xie, Xinmiao, Sun, Pengju, Sun, Chen, Zhang, He, Zheng, Xiang-ping, Wang, Xiuli, and Xie, Ling-hai
- Subjects
SPIRO compounds ,NAPHTHYLAMINES ,OXIDATION ,PHOTOSENSITIZERS ,ULTRAVIOLET lamps - Abstract
A series of spiro [fluorene-9,7′-dibenzo[c,h]acridine]-5′-one (SFDBAO) derivatives have been concisely and cleanly obtained by exposure to sunlight without external photosensitizers in the higher yields than that when using a UV lamp. An interesting autocatalyst and self-sensitive procedure have been proposed to explain the effective photooxygenation. SFDBAO derivatives exhibit the continuous
π -stacks in single-crystal and electron-withdraw properties with red light-emitting and photovoltaic properties. [ABSTRACT FROM AUTHOR]- Published
- 2018
- Full Text
- View/download PDF
27. Online Condition Monitoring for Both IGBT Module and DC-Link Capacitor of Power Converter Based on Short-Circuit Current Simultaneously.
- Author
-
Sun, Pengju, Gong, Can, Du, Xiong, Luo, Quanming, Wang, Haibo, and Zhou, Luowei
- Subjects
- *
INSULATED gate bipolar transistors , *POWER capacitors , *CONVERTERS (Electronics) , *ELECTRIC resistance , *ELECTROLYTIC capacitors , *SHORT-circuit currents - Abstract
Insulated-gate bipolar transistor (IGBT) modules and dc-link capacitors are important parts in the majority of power electronic converters which contribute to cost, size, and failure rate on a considerable scale. This paper presents an online condition monitoring method for both IGBT modules and dc-link capacitors of power converters based on short-circuit current of an IGBT module, which is a good condition indicator according to the theory analysis. The failure prediction of dc-Link capacitor is realized by equivalent series resistance, which can be calculated by short-circuit current and a step voltage, and the bond wires fatigue can also be identified by the short-circuit current. The proposed method is capable for detecting small changes in the failure indicators of IGBT modules and electrolytic capacitors, and its effectiveness is validated by a confirmatory experiment. The novelty of the proposed method is that the degradations of IGBT modules and capacitors can be identified simultaneously, and has the merits of low cost and circuit simplicity [ABSTRACT FROM PUBLISHER]
- Published
- 2017
- Full Text
- View/download PDF
28. Condition Monitoring IGBT Module Bond Wires Fatigue Using Short-Circuit Current Identification.
- Author
-
Sun, Pengju, Gong, Can, Du, Xiong, Peng, Yingzhou, Wang, Bo, and Zhou, Luowei
- Subjects
- *
INSULATED gate bipolar transistors , *ENERGY conversion , *SHORT-circuit currents , *TEMPERATURE , *ELECTRIC potential - Abstract
Finding and replacing the defective insulated-gate bipolar transistor (IGBT) module timely by monitoring the ageing state of IGBT can improve the reliability of a power converter and reduce the loss caused by IGBT failure. A method for detecting the condition of bond wires in IGBT module by identifying the short-circuit current of IGBT module is presented in this paper. It is based on the fact that parasitic parameters of IGBT module are affected by the local damage induced by ageing over time, and these changes can be easily detected by monitoring the difference of short-circuit current. The study results indicate that short-circuit current of IGBT module decreases with module ageing over time, and the difference of short-circuit current caused by junction temperature is much smaller than that caused by bond wires fatigue on a specific gate driving voltage. Therefore, the IGBT module in the power converter can be diagnosed by detecting the difference of short-circuit current without considering the effects of junction temperature. Finally, a confirmatory experiment is carried out, and the correctness of the method proposed in this paper is verified. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
29. Monitoring Potential Defects in an IGBT Module Based on Dynamic Changes of the Gate Current.
- Author
-
Zhou, Shengqi, Zhou, Luowei, and Sun, Pengju
- Subjects
INSULATED gate bipolar transistors ,LOGIC circuits ,ELECTRIC currents ,CAPACITORS ,SEMICONDUCTOR junctions ,POWER electronics ,ELECTRIC resistance - Abstract
Potential defects inside an insulated gate bipolar transistor (IGBT) module can be seen as precursors of being about to wear out, and are important for health monitoring of the IGBT module which is used to enhance reliability. A method for detecting defects in the IGBT module by identifying dynamic changes of the gate current is presented in this paper. It is based on the fact that parasitic elements inside the IGBT module are affected by local damage induced by aging over time, and subsequently, these influences are easily distinguished by dynamic changes of the gate current. The proposed prognostic approach is based on relevance vector machine framework, which can give accurate predictions and allow operators to observe unhealthy IGBT modules inside a power converter, and then take appropriate measures timely to avoid breakdown. The parasitic elements involved in the gate circuit are extracted, and their contributions to dynamic changes of the gate current are also discussed. Finally, a confirmatory experiment is carried out, and the correctness of the proposed method is verified. [ABSTRACT FROM AUTHOR]
- Published
- 2013
- Full Text
- View/download PDF
30. A Reconfigurable Structure DC–DC Converter With Wide Output Range and Constant Peak Power.
- Author
-
Sun, Pengju, Zhou, Luowei, and Smedley, Keyue Ma
- Subjects
- *
DC-to-DC converters , *ELECTRIC current converters , *SWITCHING circuits , *CAPACITORS , *ELECTRIC inverters , *THERMAL stresses , *ELECTRIC switchgear - Abstract
This paper presents a reconfigurable structure dc–dc converter with wide output range and constant peak power (RS-WOCP). This converter is an extension of the traditional isolated dc–dc converter with two output channels by adding an active switch and two diodes. Theoretical analysis indicates that the proposed RS-WOCP converter is able to smoothly reconfigure the output channels in parallel or series to realize wide output voltage range. With this approach, the output voltage is shared equally in the series operating mode and so is the output current in the parallel operating mode. Therefore, the power rating of devices is significantly reduced and the output rectifiers and filters can distribute power losses and thermal stresses. Operating principle, control strategy, modeling, and stability analysis are illustrated in this paper. An experimental prototype of a 200-W DSP-based RS-WOCP converter was built. The experimental results have verified the steady-state performance and fast dynamic response in the whole output voltage range. Comparisons with two close relatives of wide output converters show that the proposed RS-WOCP converter is advantageous for wide output range constant peak power applications. [ABSTRACT FROM AUTHOR]
- Published
- 2011
- Full Text
- View/download PDF
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