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International Conference on Electrical Machines and systems (ICEMS)

作者： Zhongkun Ji Siwei Cheng Dong Wang National Key Laboratory of Science and Technology on Vessel Integrated Power System NUE Wuhan China

This paper presents an analytical method for calculating current harmonics of PMSMs fed by three-level NPC H-bridge inverters by combining the 3-D model of the PWM pulses with PMSM state equations. The accuracy of the proposed analytical model is validated by simulation results. Characteristics of current harmonics are studied by analyzing the PWM generation process under different modulation conditions. The influence of current harmonics on the internal magnetic field of a six-phase PMSM is also evaluated by FEA.

关键词： Pulse width modulation Harmonic analysis Inverters Solid modeling Vibrations Permanent magnet motors

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Performance Comparison of Modulation and Sorting Methods for Modular Multilevel Converter

Performance Comparison of Modulation and Sorting Methods for...

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2018 3rd International Conference on Automation, Mechanical and Electrical Engineering (AMEE 2018)

作者： Qi-fan ZENG Liang-deng HU Sheng AI National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering

The modulation strategy of modular multilevel converter(MMC) needs to be combined with the sub-module(SM) redistribution strategy to maintain the stability of the SM capacitor voltage while working properly. The submodule(SM) switching frequency and the voltage balancing performance have been compared between two pulse width modulation(PWM) methods,i.e. carrier phase shift PWM(CPS-PWM) and submodule unified PWM(SUPWM), combined with two kinds of sorting methods, i.e. modulation wave compensation method and improved module selection method. The theoretical and simulation results show that when the number of sub-modules and the carrier frequency meet the requirements of ship propulsion, it is difficult for modulation wave compensation method to maintain good performance in different output frequency *** improved module selection method will increase the switching frequency of the device, but it has a higher performance in voltage balancing.

关键词： ship electric propulsion Modular multilevel converter Pulse width modulation Sorting method

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2D FEM Transient Analysis of Permanent Magnet Motor Considering Skin Effect of Stator Winding

2D FEM Transient Analysis of Permanent Magnet Motor Consider...

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IEEE International Conference on Applied Superconductivity and Electromagnetic Devices

作者： Jun Quan Chen Dong Wang Si Wei Cheng Zhong Jun Yu Yun Jun Guo Xin Qiang Yi Zhi Shu Yu National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering

ISBN: (纸本)9781467381086

In this paper, a 2D field-circuit coupled transient finite element method considering skin effect of stator current due to tooth and slot effect is proposed. It treats each turn of every phase winding in each slot as inductor element in external electric circuit. Relations between phase windings and coil are implemented by parallel or series connection of each turn. By this way, non-uniform current density and excess joule loss in stator winding could be evaluated. Finally, this method is validated by a 600kW fractional PM motor. Satisfactory agreement between calculated and measured motor performance suggests that skin effect of stator current and its resultant copper loss should be paid special attention especially when it is applied in high speed application, even though fractional-slot concentrated-winding PM motor is suitable for low speed high torque density application.

关键词： Skin effect Computational electromagnetism Fractinal motor Permanent magnet motor Finite element method

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Stability improvement of analog adaptive self-interference cancellation system with phase compensation

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Progress In Electromagnetics Research C 2019年 95卷 227-238页

作者： Zhang, Yunshuo Wang, Qing Qin, Huanding He, Fangmin Meng, Jin National Key Laboratory of Science and Technology Vessel Integrated Power System Naval University of Engineering WuhanHubei430033 China

The self-interference problem of linear frequency modulated continuous wave (LFMCW) radar is a known issue that limits the radar’s detection range. Analog adaptive interference cancellation (AIC) technique is effective to mitigate the self-interference problem. However, we find that the phase difference between the error signal and reference signal paths may significantly deteriorate the stability of the AIC system. Therefore, in this paper, we analyze the effect of phase difference on system stability through the mathematical modeling and simulation. We find that the system is stable when the phase difference is between -90 and 90 degrees, and diverges when it is between 90 and 270 degrees. Therefore, to avoid system instability, we propose to add a phase shifter in the reference signal path to compensate the phase difference. The experiment results show that compared with the traditional delay-based compensation method, our phase compensation based method can increase interference cancellation ratio (ICR) by 15 dB for a single-antenna system and 12 dB for a dual-antenna system. © 2019, Electromagnetics Academy. All rights reserved.

关键词： system stability

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A High-power and High-efficiency Ku Band RTTO with Trapezoidal Extraction Cavity

A High-power and High-efficiency Ku Band RTTO with Trapezoid...

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Progress in Electromagnetic Research Symposium (PIERS)

作者： Chaochao Yang Haitao Wang Jin Meng Zhongwu Xiang Danni Zhu Yuzhang Yuan National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University Engineering China

ISBN: (纸本)9781665409889

With the increasing demand for the output power of the device, the internal power density of the device is also increasing, and the field strength is increasing. This may result in a breakdown of the internal field of the device, creating a plasma on the internal surface of the device. The plasma effect inside the high power microwave source is the main reason that affects the long pulse operation of the device. In this section, the extraction cavity of conventional RTTO is changed from rectangular to trapezoidal to suppress the formation of plasma inside the device and its influence on the device’s long pulse operation. In particle-in-cell simulation, the proposed RTTO can output HPM with the power of 2.76 GW, the frequency of 14.16 GHz and the efficiency of 36%. The maximum radial electric field intensity in the extraction cavity is 0.8 MV/cm, so the radio frequency breakdown risk of the whole device is small.

关键词： power system measurements Electric breakdown Density measurement Simulation Microwave devices Plasmas Electromagnetics

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Crack-SegNet: Surface Crack Detection in Complex Background Using Encoder-Decoder Architecture 2021

Crack-SegNet: Surface Crack Detection in Complex Background ...

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2021 4th International Conference on Sensors, Signal and Image Processing

作者： Rong Ran Xinghua Xu Shaohua Qiu Xiaopeng Cui Fuhui Wu National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering China

ISBN: (纸本)9781450385725

Timely and accurate detection of the initiation and expansion of crack is of great significance for improving safe operation of civil infrastructures. Image-based visual surface inspection has been an indispensable way for long-time infrastructure monitoring. However, existing crack detection methods generally suffer from the interference of complex background, leading to obvious performance drops. To tackle this, an improved encoder-decoder architecture based on SegNet is proposed in this paper, namely crack-SegNet. The encoder network hierarchically learns visual features from the original image, and the decoder network gradually up-samples and maps the encoded features to the input size for the pixel-level classification. In order to enhance the feature capacity of cracks in complex background, a channel attention mechanism is integrated into the encoder, as well as a spatial attention module in the decoder to improve the feature representation of cracks. Meanwhile, a spatial pyramid pooling is also attached to the last convolutional layer of the encoder to capture crack with different scales. To better validate the proposed method, a challenging metal surface crack dataset with much more complex background is collected. Experimental results on the datasets show that the proposed crack-SegNet outperforms other state-of-the-art crack detection methods, especially in complex background.

关键词： Encoder-decoder architecture Complex background Semantic segmentation Deep convolutional neural works Surface crack detection

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Online measurement method of transformer leakage impedance by using symmetrical coupling auxiliary winding

Online measurement method of transformer leakage impedance b...

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International Conference on Magnetics (INTERMAG)

作者： R. Wang F. Xiao Z. Zhao Y. Shen National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval University of Engineering Wuhan

The transformer can be illuminated by the T-type equivalent circuit model. The primary and secondary leakage impedance characterizes the copper losses and the exciting impedance reflects iron-core losses. The iron-core losses and the copper losses can be obtained by open-circuit and short-circuit test. However, the copper losses of the primary winding and the secondary winding cannot be separated, which cannot satisfy the requirement of the cooling design of the high power transformer. The auxiliary winding method to measure the winding ac resistance of planar transformer in high-frequency switching converters is used in Reference [1], but the detailed arrangement of the auxiliary winding is not analyzed. In this paper, an inductance-coupling model of the transformer is established, and the measurement error is analyzed. Then a Symmetrical Coupling Auxiliary Winding Measurement Method (SCAWM) is proposed. The measurement accuracy of the proposed method is verified by the experiment results based on a five-winding transformer. The online copper loss during nominal medium frequency operation condition is carried out based on the above method, which achieves the separating measurement of the primary and secondary winding AC resistance.

关键词： Windings Impedance Electrical resistance measurement Impedance measurement Current measurement Voltage measurement power transformers

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Load Commutation of the Circular Winding Brushless DC Machine (CWBLDC)

Load Commutation of the Circular Winding Brushless DC Machin...

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Annual Conference of the IEEE Industrial Electronics Society

作者： Huangda Lin Siwei Cheng Dong Wang Zhewu Jia National Key Laboratory of Science and Technology on Vessel Integrated Power System Naval Univ. of Engineering

ISBN: (纸本)9781479917631

A circular winding brushless DC (CWBLDC) machine is essentially a trapezoidal-EMF multiphase permanent magnet machine with the associated commutation circuit. It can achieve the same level of torque ripple performance as sinusoidal-EMF permanent magnet synchronous machines (PMSMs), yet boast much higher torque density since the iron core is more fully utilized with trapezoidal EMFs. The commutation circuit is an integral part of this machine and should be properly controlled. This paper presents a load commutation method for CWBLDC machine, which relies on the EMF of its load (the motor) to reverse the phase current direction. power devices of the commutation circuit can be turned off with no current flowing through, which can be considered as a form of soft switching. The load commutation process is analytically derived and critical conditions for successful commutations are highlighted. Field-circuit coupled analysis have been performed to verify the load commutation method. A 10 kW, 8-pole, 46-slot CWBLDC prototype has been designed, fabricated and tested to verify the analysis.

关键词： Brushless dc(BLDC) machine Circular winding Load commutation commutating circuit iron core Commutation Permanent magnet synchronous machines LOAD brushless machine DC machines winding (process) electric current critical condition Electromagnetic fields European Monetary Fund electromotive forces

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Adaptive non-singular terminal sliding mode control for permanent magnet synchronous motor speed regulation system 5

Adaptive non-singular terminal sliding mode control for perm...

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5th IEEE Information technology, Networking, Electronic and Automation Control Conference, ITNEC 2021

作者： Li, Chuanming Guo, Yong Wang, Yachen Sun, Jingguang Jiangsu Automation Research Institute Lianyungang222061 China Northwestern Polytechnical University School of Automation Xi'an710072 China Naval University of Engineering National Key Laboratory of Science and Technology on Vessel Integrated Power System Wuhan430033 China

ISBN: (纸本)9781665415989

This paper studies the control problem of the permanent magnet synchronous motor (PMSM) combining terminal sliding mode control and adaptive control. An adaptive terminal sliding mode control strategy is designed based on the fast terminal sliding manifold, which can make sure that the system states converge to a small neighborhood around zero in finite time. A rigorous proof is proved for the designed controller via Lyapunov stability theory. The simulation results are presented to illustrate the effectiveness of the presented control scheme. © 2021 IEEE.

关键词： Robust control

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Perovskite films with gradient bandgap for self-powered multiband photodetectors and spectrometers

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Nano Research 2023年第7期16卷 10256-10262页

作者： Chuantian Zuo Lixiu Zhang Xiyan Pan He Tian Keyou Yan Yuanhang Cheng Zhiwen Jin Chenyi Yi Xiaoliang Zhang Wu-Qiang Wu Qinye Bao Liyuan Han Liming Ding Center for Excellence in Nanoscience(CAS) Key Laboratory of Nanosystem and Hierarchical Fabrication(CAS)National Center for Nanoscience and TechnologyBeijing 100190China School of Physics and Electronic Science East China Normal UniversityShanghai 200241China School of Integrated Circuits Tsinghua UniversityBeijing 100084China School of Environment and Energy South China University of TechnologyGuangzhou 510000China School of New Energy Nanjing University of Science and TechnologyJiangyin 214443China School of Physical Science and Technology Lanzhou UniversityLanzhou 730000China State Key Laboratory of Power System Department of Electrical EngineeringTsinghua UniversityBeijing 100084China School of Materials Science and Engineering Beihang UniversityBeijing 100191China School of Chemistry Sun Yat-sen UniversityGuangzhou 510006China State Key Laboratory of Metal Matrix Composites Shanghai Jiao Tong UniversityShanghai 200240China Key Laboratory of Semiconductor Materials Science Beijing Key Laboratory of Low Dimensional Semiconductor Materials and DevicesInstitute of SemiconductorsChinese Academy of SciencesBeijing 100083China

Bandgap-graded materials present varying spectral responses at different positions,making them possible to be used as an alternative to photoactive materials array in multi-spectral responsive devices,thus miniaturizing the ***,the preparation of bandgap-graded materials usually requires complicated deposition *** we report a facile lowtemperature solution process to make films with lateral bandgap gradients,which form spontaneously via self-spreading and interdiffusion of *** show lead halide perovskite films with MAPbCl_(3)-MAPbBr_(3)and MAPbBr_(3)-MAPbI_(3)gradients,which exhibit light absorption onsets ranging from 410 to 781 *** bandgap-graded films were used to make self-powered multiband photodetectors,which show different spectral responses at different positions without applying bias ***,self-powered spectrometers were made by using the multiband photodetectors.

关键词： self-spreading interdiffusion bandgap-graded perovskite multiband photodetectors self-powered spectrometers

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