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- 저자 : Liu Jilong (검색결과 10 건)
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Liu, Jilong,Xiao, Fei,Ma, Weiming,Fan, Xuexin,Chen, Wei The Korean Institute of Power Electronics 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2
This paper proposes a pulse width modulation (PWM)-based sliding mode controller (SMC) for a full-bridge DC-DC converter that can eliminate static output voltage error. Hysteretic SMC in DC-DC converter does not have a fixed switching frequency, and applying hysteretic SMC to full-bridge converters is difficult. Fixed-frequency SMC, which is also called PWM-based SMC, based on equivalent control overcomes these shortcomings. However, the controller order reduction in equivalent control in PWM-based SMC causes static output voltage error. To resolve this issue, an integral item is added to the PWM-based SMC. Sliding mode coefficients are designed by applying a standard second-order system to the sliding mode surface. The effect of adding an integral item on the controller is analyzed, and an integral coefficient design method is proposed. Experiment results on a three-level full-bridge DC-DC converter verify the control scheme and design method proposed in this paper.
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Jilong Liu,Fei Xiao,Weiming Ma,Xuexin Fan,Wei Chen 전력전자학회 2015 JOURNAL OF POWER ELECTRONICS Vol.15 No.2
This paper proposes a pulse width modulation (PWM)-based sliding mode controller (SMC) for a full-bridge DC-DC converter that can eliminate static output voltage error. Hysteretic SMC in DC-DC converter does not have a fixed switching frequency, and applying hysteretic SMC to full-bridge converters is difficult. Fixed-frequency SMC, which is also called PWM-based SMC, based on equivalent control overcomes these shortcomings. However, the controller order reduction in equivalent control in PWM-based SMC causes static output voltage error. To resolve this issue, an integral item is added to the PWM-based SMC. Sliding mode coefficients are designed by applying a standard second-order system to the sliding mode surface. The effect of adding an integral item on the controller is analyzed, and an integral coefficient design method is proposed. Experiment results on a three-level full-bridge DC-DC converter verify the control scheme and design method proposed in this paper.
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A Small Baseline Stereo Matching Method Based on Adaptive Weight
Jilong Bian,Jinfeng Li,Nana Wang,Liu Yang 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.9
Due to a high percentage of the bad pixels in small baseline stereo matching method, a small baseline stereo matching method based on adaptive weight is proposed. Firstly, the size of reference window is adaptively calculated for each reference point and then matching costs is evaluated according to adaptive weights and reference window size. Secondly, winner take all is used to evaluate initial disparities and unreliable matches are refused by using reliability constraints. Finally, disparity post processing method based on iterative diffuse using a new cost function is used to obtain a dense disparity map. A small baseline stereo image pair of Toulouse and stereo image pairs provided by the benchmark Middlebury database are used to test the proposed method. The experimental results show that this method can effectively reduce a percentage of the bad pixels of depth discontinuity areas, improve the overall disparity matching accuracy and meet the requirements of small baseline three-dimensional reconstruction.
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Mu Yalu,Liu Jilong,Mai Zhiqin,Xiao Fei,Li Shun 대한전기학회 2024 Journal of Electrical Engineering & Technology Vol.19 No.4
In a permanent magnet synchronous motor (PMSM) drive system without voltage sensor, aff ected by the inverter non-linearities, there is a phase off set problem between the reconstructed voltage and the actual voltage. This phase off set increases as the switching frequency decreases, especially pronounced in subway permanent magnet traction systems operating at the hundreds of Hertz level. As a result, in the medium-to high-speed range, the estimated rotor position progressively advances ahead of the actual rotor position, accompanied by an increasing content of estimated speed harmonics. To address this issue, this paper proposes a sensorless control performance optimization strategy for low switching frequency permanent magnet drive systems. On the one hand, the position error compensation strategy of voltage phase advance adjustment is adopted to eliminate the phase off set between the actual voltage and the reconstructed voltage. On the other hand, the method of cascading the adaptive notch fi lter with the low-pass fi lter is used to eliminate the harmonic interference in the feedback current, so as to realize the harmonic suppression of the estimated speed. The experimental results have confi rmed the eff ectiveness of the proposed optimization strategy, ultimately the position sensorless control of the PMSM drive system with the inverter switching frequency of 500 Hz was achieved, eff ectively optimizing the control performance at low switching frequencies.
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Optimal modulation strategy based on fundamental reactive power for dual‑active‑bridge converters
Zhichao Zhu,Fei Xiao,Jilong Liu,Peng Chen,Zhaojie Huang,Qiang Ren 전력전자학회 2021 JOURNAL OF POWER ELECTRONICS Vol.21 No.12
Dual-active-bridge (DAB) converters are widely used in bidirectional power transmission and voltage conversion. At present, phase-shift (PS) control is one of the most common and mature control methods for DAB converters. To improve the efficiency and performance of DAB converters, the soft switching and current stress are optimized by increasing the inner phaseshift ratio. However, under different PS controls, it is difficult to establish a unified mathematical model using the traditional instantaneous integral method. To solve this problem, based on the approximate equivalence of the fundamental component of a high-frequency link decomposed by Fourier series, an optimal fundamental modulation strategy is proposed, which takes the fundamental reactive power as the objective of optimization. The trajectories for each of the electrical parameters are analyzed intuitively through a vector diagram of the phasor. A practical optimal control strategy scheme for engineering is obtained. Finally, the effectiveness of the theoretical analysis and the proposed method are verified by experimental results.
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Weiwei Zhang,Fei Xiao,Jilong Liu,Zhiqin Mai,Chaoran Li 대한전기학회 2020 Journal of Electrical Engineering & Technology Vol.15 No.4
Rail transportation interior permanent magnet synchronous motor traction control system (IPMSM TCS) requires high torque output capability. Traditional algorithms used to fnd the maximum torque per ampere (MTPA) operating point in TCS have strong dependence on motor parameters. Because the algorithm is less robust to motor parameters, there will be deviation between the MTPA operating point and the actual value when the parameters change, so that it is difcult to guarantee the torque output capability of the traction system under diferent working conditions. This paper introduces a current angle signal injection control method (CASIM) to solve this problem. The proposed method tracks the MTPA operating point and generates d-axis current command according injecting an angle signal to current and making the partial derivative of torque to current angle equal to zero. At the same time, less motor parameters are needed to calculate the torque in this method. Consequently, in the process of looking for MTPA operating point, the accuracy is less afected by the variation of motor parameters. And also it does not inject any real signal to IPMSM, so that it does not increase copper and iron losses. Moreover, it is robust to speed mutation and torque disturbances. The efectiveness of CASIM proposed in this paper is proved by simulation and experiment results on an IPMSM TCS platform.
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Zhu Zhichao,Xiao Fei,Liu Jilong,Chen Peng,Ren Qiang,Huang Zhaojie 대한전기학회 2022 Journal of Electrical Engineering & Technology Vol.17 No.3
The dual active bridge (DAB) DC-DC converter has broad prospects for use, for example, energy-storage systems, electric vehicles, and DC distribution network. To improve the quality of bus current, researchers often cascade fi lter inductors to the DC port of DAB converter. If so, the system may be instable and oscillate because the converter is turned into a cascaded structure of LC fi lter and DAB converter. In addition, it is found that the output current is used as the feedback variable for closed-loop control in bidirectional transmission, which will increase the number of sensors. And, the current of the energy storage unit (ESU) cannot be directly controlled when the ESU discharges. To solve these problem, this paper proposes a control strategy based on notch fi lter (NF) regulator. Regardless of whether power fl ows in the forward or reverse direction, the fi lter inductor current is always regarded as control objectives. For this purpose, NF regulator is introduced into the forward path of the current loop to suppress the oscillation of the LC fi lter inductor current. Finally, the eff ectiveness of the theoretical analysis and proposed strategy are verifi ed by simulations and experiments.
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Optimization of maximum torque output in the wide speed range of a PMSM traction control system
Zhang, Weiwei,Xiao, Fei,Liu, Jilong,Mai, Zhiqin,Li, Chaoran The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.1
This paper introduces a permanent magnet synchronous motor maximum torque control method for the wide speed range of a traction control system. This method tracks the maximum torque per ampere operating point and generates a d-axis current command according to the injection of a high-frequency angle signal to the current. This method is parameter independent when looking for the maximum torque per ampere operating point. By not injecting any real signal to a permanent magnet synchronous motor, this method does not increase the amount of copper and iron losses resulting from real signal injection. To obtain a maximum torque output in a wide speed range, this method considers the maximum amplitude limits of voltage and current when the traction motor runs in a flux weakening control field. This method is also robust to current and voltage harmonics, speed mutations, and torque disturbances. Experiment and analysis are conducted on a permanent magnet synchronous motor traction control system prototype under various operating conditions to verify the effectiveness of this method.
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Peng Chen,Fei Xiao,Jilong Liu,Zhichao Zhu,Zhaojie Huang 전력전자학회 2022 JOURNAL OF POWER ELECTRONICS Vol.22 No.5
Modular multilevel converter–bidirectional DC–DC converter (MMC–BDC) is a prospective solution for the bidirectional DC–DC power conversion between medium-voltage DC (MVDC) bus and distributed energy storage system. Researchers have studied its application in the shipboard power system. In face of distributed energy storage devices with discrepant state of charge (SOC), the sub-modules (SMs) of MMC–BDC should work under inconsistent power to unify the SOC level. The existing unbalanced SM power control strategies fail to consider unbalanced operation range and efficiency. Therefore, this study proposes a novel unbalanced control strategy based on the feedforward compensation method, which is characterized by inconsistent SM voltage. Comparisons are made to demonstrate the advantages of the proposed strategy over traditional ones, and the dynamic characteristics are analyzed. Simulation and experiment results illustrate the effectiveness of the proposed unbalanced operation strategy.
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Phase II trial of VEGFR2 inhibitor apatinib for metastatic sarcoma: focus on efficacy and safety
Zhichao Liao,Feng Li,Chao Zhang,Lei Zhu,Yehui Shi,Gang Zhao,Xu Bai,Shafat Hassan,Xinyue Liu,Ting Li,Peipei Xing,Jun Zhao,Jin Zhang,Ruwei Xing,Sheng Teng,Yun Yang,Kexin Chen,Jilong Yang 생화학분자생물학회 2019 Experimental and molecular medicine Vol.51 No.-
Apatinib (YN968D1) is a novel tyrosine kinase inhibitor targeting vascular endothelial growth factor receptor 2 (VEGFR- 2). We conducted a single-arm, nonrandomized phase II study (NCT03121846) to assess the efficacy and safety of apatinib in patients with stage IV sarcoma. We recruited 64 patients with stage IV sarcoma who had failed chemotherapy. The primary endpoint was progression-free survival (PFS), and the secondary endpoints were progression-free survival rate (PFR), objective response rate (ORR), and disease control rate (DCR) at week 12. Treatment-related adverse effects (AEs) were evaluated. Fifty-nine patients were assessed for efficacy and 64 patients for AEs. The median PFS was 7.93 months. At 12 weeks, the PFR was 74%, the ORR was 16.95% (10/59), and the DCR was 86.44% (51/59). The final ORR was 15.25% (9/59) and the DCR was 57.63% (34/59). Notably, 22 patients (34.38%) who developed hypertension, hand-foot-skin reaction, or proteinuria had significantly longer OS than those without these AEs (18.20 vs. 10.73 months; P = 0.002). We conclude that apatinib is effective and well tolerated in patients with advanced sarcoma. The development of hypertension, hand-foot-skin reaction, or proteinuria may indicate a favorable prognosis, representing a novel finding in sarcoma patients.
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