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526 results on '"Wang, Jia-Jun"'

58. Rotor Position Estimation Using Harmonic-Decomposition Complex-Coefficient Filter-Based PLL for PMSM With Switch Hall-Effect Sensors

Author

Xin, Zhuang-Zhuang, Wang, Jia-Jun, and Zhao, Hong-Jiang

Abstract

Three Hall-effect sensors can be used to estimate the continuous rotor position of permanent magnet synchronous motors (PMSMs) at a low cost. However, available position estimation methods generally require motor model parameters or have a phase offset. For this purpose, this article proposes a harmonic-decomposition complex-coefficient filter-based phase-locked loop (HD-CCF-PLL) structure that is independent of motor parameters and has a near-zero phase offset. First, the triggering principle of Hall-effect sensors is introduced, and the effect of Hall position error on current harmonics and torque ripples is analyzed. Then, coordinate transformation and harmonic decomposition methods are presented for three Hall-effect sensors. However, there is a limit to the number of times a microcontroller can perform real-time harmonic decomposition. The decomposed Hall position vector still contains high-order harmonics, which reduces position estimation accuracy. Therefore, a CCF-PLL technique is employed to filter out these harmonics and estimate the rotor position. An efficient method of CCF-PLL online parameter self-adjustment is also provided for adapting to different speeds. Finally, the effectiveness of the proposed method is verified by detailed experiments. The results show that the proposed method can effectively filter out the harmonics in the Hall position vector with higher position estimation accuracy, fewer current total current harmonic distortion, and a smaller torque ripple than the existing method.

Published
2024
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68. Research of Chain Circuit STATCOM Based on CPS-SPWM Modulatio

Author

ZHAO Qiang and WANG Jia-jun

Subjects
coal mine power grid, static synchronous compensator, cascade h-bride, multi-level, unipolar cps-spwm, bipolar cps-spwm, statcom, Mining engineering. Metallurgy, TN1-997
Abstract

In view of problem that nonlinear and impact load inject plenty of reactive power and harmonic wave into coal mine power grid, the paper researched chain circuit STATCOM based on CPS-SPWM modulation. It introduced main circuit structure of chain circuit STATCOM; for two modulations of unipolar CPS-SPWM and bipolar CPS-SPWM in chain circuit STATCOM, it used Matlab to analyze differences between unipolar CPS-SPWM modulation and bipolar CPS-SPWM modulation based on H-bridge basic module and cascade H-bridge, the simulation result showed that waveform quality of unipolar CPS-SPWM modulation is superior to one of bipolar CPS-SPWM modulation, so chain circuit STATCOM should select unipolar CPS-SPWM modulation; it used Matlab/Simulink platform to make simulation for chain circuit STATCOM based on unipolar CPS-SPWM modulation under different modulation ratios, the simulation result showed that the chain circuit STATCOM has characteristics of good output waveform, low harmonics and strong expandability.

Published
2012

71. Effective transport network driven by tortuosity gradient enables high-electrochem-active solid-state batteries.

Author

Liu, Qing-Song, An, Han-Wen, Wang, Xu-Feng, Kong, Fan-Peng, Sun, Ye-Cai, Gong, Yu-Xin, Lou, Shuai-Feng, Shi, Yi-Fan, Sun, Nan, Deng, Biao, Wang, Jian, and Wang, Jia-Jun

Subjects
SOLID state batteries, TORTUOSITY, ELECTROCHEMICAL analysis, STORAGE batteries, CATHODES
Abstract

Simultaneously achieving high electrochemical activity and high loading for solid-state batteries has been hindered by slow ion transport within solid electrodes, in particular with an increase in electrode thickness. Ion transport governed by 'point-to-point' diffusion inside a solid-state electrode is challenging, but still remains elusive. Herein, synchronized electrochemical analysis using X-ray tomography and ptychography reveals new insights into the nature of slow ion transport in solid-state electrodes. Thickness-dependent delithiation kinetics are spatially probed to identify that low-delithiation kinetics originate from the high tortuous and slow longitudinal transport pathways. By fabricating a tortuosity-gradient electrode to create an effective ion-percolation network, the tortuosity-gradient electrode architecture promotes fast charge transport, migrates the heterogeneous solid-state reaction, enhances electrochemical activity and extends cycle life in thick solid-state electrodes. These findings establish effective transport pathways as key design principles for realizing the promise of solid-state high-loading cathodes. [ABSTRACT FROM AUTHOR]

Published
2023
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74. Deactivation and regeneration of a benchmark Pt/C catalyst toward oxygen reduction reaction in the presence of poisonous SO2 and NO

Author

Liu, Yu-Xin, primary, Zhang, Wei-Yi, additional, Han, Guo-Kang, additional, Zhou, Ya-Wei, additional, Li, Ling-Feng, additional, Kang, Cong, additional, Kong, Fan-Peng, additional, Gao, Yun-Zhi, additional, Du, Chun-Yu, additional, Wang, Jia-Jun, additional, Ma, Yu-Lin, additional, Du, Lei, additional, Cai, Wen-Bin, additional, and Yin, Ge-Ping, additional

Published
2022
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