Robust Time Delay Compensation for DTC-Based Induction Machine Systems via Extended State Observers

Wang, Fengxiang,Wang, Junxiao,Yu, Li The Korean Institute of Power Electronics 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper presents an extended state observer (ESO) based direct torque control (DTC) for use in induction motor systems to handle the issues of time delays, load torque disturbances and parameter uncertainties. Direct torque control offers an excellent torque response and it does not require a proportion integration (PI) controller in the current loop. However, a PI controller is still adopted in the outer speed loop to generate the torque reference value, which is a slow method. An ESO based compound control scheme is proposed to improve the response rate and accuracy of the torque reference signal, especially when load torque is injected. In addition, the time delay problem is analyzed and compensated for in this paper to reduce torque ripples. The proposed disturbance compensation technique based direct control scheme is shown to have good performance both in the transient and stable states via simulations and experimental results.

Robust Time Delay Compensation for DTC-Based Induction Machine Systems via Extended State Observers

Fengxiang Wang,Junxiao Wang,Li Yu 전력전자학회 2018 JOURNAL OF POWER ELECTRONICS Vol.18 No.3

This paper presents an extended state observer (ESO) based direct torque control (DTC) for use in induction motor systems to handle the issues of time delays, load torque disturbances and parameter uncertainties. Direct torque control offers an excellent torque response and it does not require a proportion integration (PI) controller in the current loop. However, a PI controller is still adopted in the outer speed loop to generate the torque reference value, which is a slow method. An ESO based compound control scheme is proposed to improve the response rate and accuracy of the torque reference signal, especially when load torque is injected. In addition, the time delay problem is analyzed and compensated for in this paper to reduce torque ripples. The proposed disturbance compensation technique based direct control scheme is shown to have good performance both in the transient and stable states via simulations and experimental results.

Robust sensorless FCS-PCC control for inverter-based induction machine systems with high-order disturbance compensation

Wang, Junxiao,Wang, Fengxiang The Korean Institute of Power Electronics 2020 JOURNAL OF POWER ELECTRONICS Vol.20 No.5

Due to its theoretically fast dynamic response with unlimited bandwidth for direct switch-driven-based induction machines, the finite control set predictive current control (FCS-PCC) method has been verified to be an effective solution in recent years. However, dynamic limitations of the outer speed PI controller exist, especially with high-order time-varying disturbances. In addition, hardware cost can be reduced. Using the universal proportional integral observer (UPIO) method, a robust deadbeat-like encoderless-based FCS-PCC control scheme is investigated for induction machine systems in this paper. The encoder is avoided using the proposed sensorless method. In addition, the system response and disturbance attenuation are enhanced in presence of time-varying unknown load torque and uncertainties. The squared norm is adopted for the cost function design to ensure system stability. Experimental results illustrate that it has good performance such as fast dynamics, good low-speed steady-state accuracy, and robustness.

Measurement of Intra-Fraction Displacement of the Mediastinal Metastatic Lymph Nodes Using Four-Dimensional CT in Non-Small Cell Lung Cancer

Suzhen Wang,Jianbin Li,Yingjie Zhang,Wei Wang,Fengxiang Li,Tingyong Fan,Min Xu,Qian Shao 대한영상의학회 2012 Korean Journal of Radiology Vol.13 No.4

Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy. Objective: To measure the intra-fraction displacements of the mediastinal metastatic lymph nodes by using four-dimensional CT (4D-CT) in non-small cell lung cancer (NSCLC). Materials and Methods: Twenty-four patients with NSCLC, who were to be treated by using three dimensional conformal radiation therapy (3D-CRT), underwent a 4D-CT simulation during free breathing. The mediastinal metastatic lymph nodes were delineated on the CT images of 10 phases of the breath cycle. The lymph nodes were grouped as the upper, middle and lower mediastinal groups depending on the mediastinal regions. The displacements of the center of the lymph node in the left-right (LR), anterior-posterior (AP), and superior-inferior (SI) directions were measured. Results: The mean displacements of the center of the mediastinal lymph node in the LR, AP, and SI directions were 2.24 mm, 1.87 mm, and 3.28 mm, respectively. There were statistically significant differences between the displacements in the SI and LR, and the SI and AP directions (p < 0.05). For the middle and lower mediastinal lymph nodes, the displacement difference between the AP and SI was statistically significant (p = 0.005; p = 0.015), while there was no significant difference between the LR and AP directions (p < 0.05). Conclusion: The metastatic mediastinal lymph node movements are different in the LR, AP, and SI directions in patients with NSCLC, particularly for the middle and lower mediastinal lymph nodes. The spatial non-uniform margins should be considered for the metastatic mediastinal lymph nodes in involved-field radiotherapy.

FPGA HiL Simulation of Back-to-Back Converter PMSG Wind Turbine Systems

Zhenbin Zhang,Fengxiang Wang,Metehan Acikgoz,Xinbo Cai,Ralph Kennel 전력전자학회 2015 ICPE(ISPE)논문집 Vol.2015 No.6

This work presents a back-to-back power converter Permanent-magnet Synchronous Generator (PMSG) wind turbine real-time simulation system based on FPGA Hardware-in-the-Loop (HiL) concept. The proposed system can be used for Electric Control Units (ECUs) evaluation in a real-time manner. The refreshing rate effect of a HiL emulator is discussed and analyzed with real-time simulation proof. Within this work, perunit system model of a 2MW Back-to-Back converter direct-drive PMSG wind turbine system is developed both in continuous and discrete formats. The effectiveness of the discrete per-unit system model is firstly verified through off-line simulation in Matlab/Simulink environment. Then by using a so-called Single-Cycle-Timed- Loop (SCTL) technique, the per-unit discrete system model is implemented on an FPGA based platform as the emulator, achieving a very high refreshing-rate (up to 250 kHz, i.e., 4μs). The emulator refreshing rate effect is evaluated in a real-time operating manner by implementing an ECU (using FOC/VOC control scheme) in a second FPGA chassis. At the end of this paper the results are analyzed and theoretically interpreted.

Quantitative validation of the analytical mode shapes of a beam-like structure with a Z-shaped configuration

Wenhua Hu,Fengxiang Wang,Dongxing Cao,Jianen Chen,Jingjing Feng 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.5

Beam-like structures are widely used in engineering. The accuracy of the analytical mode shapes of these structures is important for studying their dynamic characteristics. A method is presented in this study to theoretically obtain and quantitatively validate the analytical mode shapes of a beam-like structure with a Z-shaped configuration. The governing equations and boundary conditions of the structure’s planar motion are derived using Hamilton’s principle. Frequencies and analytical mode shapes of the structure are theoretically obtained and compared with the numerical results from finite element method. The comparison of frequencies and modal assurance criterion is used to quantitatively validate the analytical mode shapes. Examples are presented to show the analytical mode shapes of Zshaped beams with different fold angles. The proposed method is useful for improving the accuracy of analytical mode shapes, which is beneficial to the design and control of beam-like structures in engineering fields.

Fluorometric determination of Fe3+ and polychlorinated benzenes based on Tb3+-pyromellitic acid coordination polymer

Linli Hou,Yonghai Song,Fengxiang Lang,Zhenrong Wang,Li Wang 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.90 No.-

A luminescent Tb3+-pyromellitic acid (H4L = pyromellitic acid) coordination polymer (Tb-H4L CP, TbL0.5(H2L)0.5(H2O)DMF) was prepared for multiresponsive fluorescence sensor. The Tb-H4L CP exhibits uniform nanospheres with average diameter of 220 20 nm, good crystalline structure, and good dispersion in water. The Tb-H4L CP emitted the characteristic green fluorescence through antenna effect from H4L which was an excellent antenna molecule when excited at 270 nm and could be used to selectively determine Fe3+ and polychlorinated benzenes based on fluorescence quenching effect. The coordination between Fe3+ and carboxylic oxygen of Tb-H4L to damage the antenna effect and polychlorinated benzenes absorb the excitation light to result the inner-filter effect of fluorescence, which quenched the fluorescence of Tb-H4L CP. The linear range for Fe3+ was 2.0–100mM with a detection limit of 0.7mM and for 1,3,5-trichlorobenzene was 0–0.44 103 ppm with a detection limit of 0.087 ppm. The Tb-H4L CP demonstrates excellent fluorescence sensing performances, indicating that it can be used as a multi-response sensor to effectively measure toxic and harmful substances.

Facile and Effective Preparation of the Lotus Leaf-based Adsorbent by Exposing Cellulose Nanocrystal for Waste Water Treatment and Air Purification

Huiyu Yang,Ke Liu,Xin Liu,Yaling Wang,Keshuai Liu,Fengxiang Chen,Bo Deng,Weilin Xu 한국섬유공학회 2020 Fibers and polymers Vol.21 No.2

One substantial plant waste, lotus leave was fabricated into lotus leave powder with different diameters by ball milling. The surface morphology, chemical composition, particle size, porosity parameters, crystal structure, and wettabilityof lotus leaf powders (LLPs) were analyzed by scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Fourier-transform infrared (FT-IR) spectroscopy, X-ray photoelectron spectroscopy (XPS), laser particle size analysis, N2 adsorption/desorption, X-ray diffraction (XRD) analysis, and water contact angle (WCA) analysis, respectively. The results showed that the micro- and nanoscale waxy papilla structures on the surface of the lotus leaf were gradually destroyed by mechanical forces along with extended balling time. Accompanied re-exposing of -OH affluent cellulose nanocrystals (CNCs) was proved by HR-TEM, XRD, and FTIR. FTIR also revealed a hydroxyl to carboxyl transition on the surface of CNCs. Both the re-exposure of CNCs and thereof chemical structure transition after ball millingmade the LLP a good candidate for pollutant adsorbent for dye, formaldehyde, and heavy metal ions.

A Dual Functional Ti-Ga Alloy: Inhibiting Biofilm Formation and Osteoclastogenesis Differentiation via Disturbing Iron Metabolism

Fupeng Li,Kai Huang,Jinbing Wang,Kai Yuan,Yiqi Yang,Yihao Liu,Xianhao Zhou,Keyu Kong,Tao Yang,Jian He,Chunjie Liu,Haiyong Ao,Fengxiang Liu,Qian Liu,Tingting Tang,Shengbing Yang 한국생체재료학회 2023 생체재료학회지 Vol.27 No.00

Background Although biomedical implants have been widely used in orthopedic treatments, two major clinical challenges remain to be solved, one is the bacterial infection resulting in biofilm formation, and the other is aseptic loosening during implantation due to over-activated osteoclastogenesis. These factors can cause many clinical issues and even lead to implant failure. Thus, it is necessary to endow implants with antibiofilm and aseptic looseningprevention properties, to facilitate the integration between implants and bone tissues for successful implantation. To achieve this goal, this study aimed to develop a biocompatible titanium alloy with antibiofilm and anti-aseptic loosening dual function by utilizing gallium (Ga) as a component. Methods A series of Ti-Ga alloys were prepared. We examined the Ga content, Ga distribution, hardness, tensile strength, biocompatibility, and anti-biofilm performance in vitro and in vivo. We also explored how Ga3+ ions inhibited the biofilm formation of Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) and osteoclast differentiation. Results The alloy exhibited outstanding antibiofilm properties against both S. aureus and E. coli in vitro and decent antibiofilm performance against S. aureus in vivo. The proteomics results demonstrated that Ga3+ ions could disturb the bacterial Fe metabolism of both S. aureus and E. coli, inhibiting bacterial biofilm formation. In addition, Ti-Ga alloys could inhibit receptor activator of nuclear factor-κB ligand (RANKL)-dependent osteoclast differentiation and function by targeting iron metabolism, then suppressing the activation of the NF-κB signaling pathway, thus, showing their potential to prevent aseptic loosening. Conclusion This study provides an advanced Ti-Ga alloy that can be used as a promising orthopedic implant raw material for various clinical scenarios. This work also revealed that iron metabolism is the common target of Ga3+ ions to inhibit biofilm formation and osteoclast differentiation.

Performance Evaluation Between SMPTC and PTC for PMSM Drives

Cristian Garcia,Jose Rodriguez,Margarita Norambuena,S. Alireza Davari,Fengxiang Wang,Yongchang Zhang 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5

Finite-set model predictive torque control (PTC) has been proposed as an attractive control strategy for drives, presenting high dynamic performance and a simple implementation. Its simplicity is due to the evaluation of single cost function based on the mathematical model prediction, however, the cost function needs a weighting factor to normalize and/or increase the importance of one of them control objectives, in this case torque and flux. Nowadays these weighting factors are a problem because there is no analytical method to determine its value, only there are some recommendations or suggestions for some specific applications. This paper validates the sequential model predictive torque control (SMPTC), which is a new strategy that does not need weighting factors, in a permanent magnet synchronous machine (PMSM) drives and compares its performance with the PTC standard. Simulation results are presented to demonstrate the good performance of SMPTC for PMSM and make the comparison with the PTC standard.