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121 results on '"Cao, Xueqian"'

27. A Single-Stage High-Frequency-Link Split-Phase Microinverter for Both Grid-Tied and Islanded Operation

Author

Li, Xuewen, Liu, Jia, Ji, Fangchao, Cao, Xueqian, Wang, Yue, and Liu, Jinjun

Abstract

High-frequency-link (HFL) inverters have drawn a lot of attention, owing to their high transformer utilization factor, bidirectional energy transfer, and easy implementation of soft switching. Therefore, HFL-based topologies might be a promising solution for the next-generation 600-W class microinverter. However, the utilization of HFL structures in split-phase systems, and the ability to operate in both grid-tied and islanded modes are rarely studied. Therefore, a novel single-stage HFL voltage-source microinverter with a split-phase structure is proposed in this article. The proposed microinverter can provide a split-phase output voltage to match the single-phase three-wire distribution system. The two-phase output voltages can be balanced naturally without dedicated control. Meanwhile, all switches achieve soft-switching by the proposed secondary-side modulation strategy. Owing to the voltage-source-inverter feature, the proposed microinverter can be used in both grid-connected and islanded applications, of which the control strategy is also proposed in this article. Finally, its dual-mode operation is validated via a 600-W/50-Hz prototype, with a peak efficiency of 94.6%.

Published
2024
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33. Investigation of the Tribological Properties and Corrosion Resistance of Multilayer Si-DLC Films on the Inner Surfaces of N80 Steel Pipes.

Author

Wang, Shaolong, Zhang, Guangan, Fu, Anqing, Cao, Xueqian, Yin, Chengxian, and Liu, Zhengyu

Subjects
STEEL pipe, DIAMOND-like carbon, CORROSION resistance, MECHANICAL wear, STEEL corrosion, ABRASIVES
Abstract

In order to solve the problem of the corrosion and wear of N80 metal pipelines exposed to corrosive media and abrasive sand during the development of petroleum resources, the proposed solution involves utilizing HC-PECVD technology to deposit a series of multilayer Si-DLC films with varying thicknesses on the inner surfaces of the N80 steel pipes. This investigation systematically explored the microstructure, mechanical properties, tribological features, and corrosion resistance of the multilayer Si-DLC films. Remarkably, after coating the multilayer (Si-DLC)40 film on the inner wall of the N80 tube, the friction coefficient decreased from 0.7~0.75 to 0.2~3, and the wear rate decreased by two orders of magnitude. In addition, the corrosion current decreased by 50%, and the impedance doubled in a 3.5 wt% NaCl solution saturated with CO2. Thus, the multilayer (Si-DLC)40 film on the inner wall of the N80 tube exhibited superior tribological properties and exceptional corrosion resistance. These findings are anticipated to furnish valuable data and technical insights for mitigating corrosion in N80 steel pipes during petroleum exploitation. [ABSTRACT FROM AUTHOR]

Published
2024
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35. Adaptive-SMO-Based Traction Force Fluctuation Suppression Strategy Considering Suspension System for High-Speed Maglev Train

Author

Zhu, Jinquan, Cao, Xueqian, Ge, Qiongxuan, and Zeng, Dihui

Abstract

The excitation pole of the long stator linear synchronous motor (LSLSM) used to drive the high-speed maglev train is also used as the suspension electromagnet, which makes the adjustment of the suspension system affect the excitation flux linkage of the motor when the train is running at high speed, resulting in significant nonperiodic traction force fluctuations. This article proposes a traction force fluctuation suppression strategy based on the flux linkage observation. First, based on the mathematical model of the LSLSM in double feed mode, the voltage equation based on the new extended back electromotive force is derived, which is less sensitive to the changes of parameters, load current, and speed, so that the flux linkage can be estimated more accurately. Then, to meet the high dynamic requirements of flux linkage observation at high speed, a sliding mode flux linkage observer is designed and a design method of the adaptive sliding mode gain is proposed to achieve fast convergence of the system. Finally, the stator reference current required to suppress the traction force fluctuation is calculated. Hardware-in-the-loop experiments verify the effectiveness of the strategy.

Published
2024
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43. Improved Sliding Mode Traction Control Combined Sliding Mode Disturbance Observer Strategy for High-Speed Maglev Train.

Author

Cao, Xueqian, Ge, Qiongxuan, Zhu, Jinquan, Kong, Ganlin, Zhang, Bo, and Wang, Xiaoxin

Abstract

To improve the robustness and dynamic tracking performance of the stator current control for the long stator linear synchronous motor (LSLSM) used in high-speed maglev train traction system, a composite current control strategy combining a sliding mode current controller (SMCC) and a sliding mode disturbance observer (SMDO) is proposed in this article. First, the LSLSM mathematical model in double feed mode is optimized. Then, an SMCC is designed based on the model. An improved stability criterion is proposed and the SMCC switching gain is obtained quantitatively to meet the current following speed required for the stator changeover process. As disturbance factors, parameter perturbation of the LSLSM and the stator changeover will bring about transient current fluctuations and chattering. Therefore, an SMDO is designed to estimate the disturbances and perform feed-forward compensation for the SMCC, thereby improving the robustness and suppressing the current chattering. Finally, the hardware-in-the-loop experiments verify the effectiveness of this strategy and compare it with the traditional current control strategy. [ABSTRACT FROM AUTHOR]

Published
2023
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