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Control of Electrically Excited Synchronous Motors with a Low Switching Frequency
Qing-qing Yuan,Xiao-jie Wu,Peng Dai,Xiao Fu 전력전자학회 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component (im) and the torque component (it). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between im and it. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.
Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency
Qing-qing YUAN,Kun XIA 대한전기학회 2015 Journal of Electrical Engineering & Technology Vol.10 No.1
Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components id and iq with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for id and iq is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.
Current Decoupling Control for the Three-level PWM Rectifier with a Low Switching Frequency
Yuan, Qing-Qing,Xia, Kun The Korean Institute of Electrical Engineers 2015 Journal of Electrical Engineering & Technology Vol.10 No.1
Three-level PWM rectifiers applied in medium voltage applications usually operate at low switching frequency to keep the dynamic losses under permitted level. However, low switching frequency brings a heavy cross-coupling between the current components $i_d$ and $i_q$ with a poor dynamic system performance and a harmonic distortion in the grid-connecting current. To overcome these problems, a mathematical model based on complex variables of the three-level voltage source PWM rectifier is firstly established, and the reasons of above issues resulted from low switching frequency have been analyzed using modern control theory. Then, a novel control strategy suitable for the current decoupling control based on the complex variables for $i_d$ and $i_q$ is designed here. The comparisons between this kind of control strategy and the normal PI method have been carried out. MATLAB and experimental results are given in detail.
Rotor Initial Position Estimation Based on sDFT for Electrically Excited Synchronous Motors
Yuan, Qing-Qing,Wu, Xiao-Jie,Dai, Peng The Korean Institute of Power Electronics 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
Rotor initial position is an important factor affecting the control performance of electrically excited synchronous motors. This study presents a novel method for estimating rotor initial position based on sliding discrete Fourier transform (sDFT). By injecting an ac excitation into the rotor winding, an induced voltage is generated in stator windings. Through this voltage, the stator flux can be obtained using a pure integral voltage model. Considering the influence from a dc bias and an integral initial value, we adopt the sDFT to extract the fundamental flux component. A quadrant identification model is designed to realize the accurate estimation of the rotor initial position. The sDFT and high-pass filter, DFT, are compared in detail, and the contrast between dc excitation and ac injection is determined. Simulation and experimental results verify that this type of novel method can eliminate the influence of dc bias and other adverse factors, as well as provide a basis for the control of motor drives.
Rotor Initial Position Estimation Based on sDFT for Electrically Excited Synchronous Motors
Qing-qing Yuan,Xiao-jie Wu,Peng Dai 전력전자학회 2014 JOURNAL OF POWER ELECTRONICS Vol.14 No.3
Rotor initial position is an important factor affecting the control performance of electrically excited synchronous motors. This study presents a novel method for estimating rotor initial position based on sliding discrete Fourier transform (sDFT). By injecting an ac excitation into the rotor winding, an induced voltage is generated in stator windings. Through this voltage, the stator flux can be obtained using a pure integral voltage model. Considering the influence from a dc bias and an integral initial value, we adopt the sDFT to extract the fundamental flux component. A quadrant identification model is designed to realize the accurate estimation of the rotor initial position. The sDFT and high-pass filter, DFT, are compared in detail, and the contrast between dc excitation and ac injection is determined. Simulation and experimental results verify that this type of novel method can eliminate the influence of dc bias and other adverse factors, as well as provide a basis for the control of motor drives.
Control of Electrically Excited Synchronous Motors with a Low Switching Frequency
Yuan, Qing-Qing,Wu, Xiao-Jie,Dai, Peng,Fu, Xiao The Korean Institute of Power Electronics 2012 JOURNAL OF POWER ELECTRONICS Vol.12 No.4
The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component ($i_m$) and the torque component ($i_t$). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between $i_m$ and $i_t$. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.
Yuan, Zi-Xu,Ma, Teng-Hui,Zhong, Qing-Hua,Wang, Huai-Ming,Yu, Xi-Hu,Qin, Qi-Yuan,Chu, Li-Li,Wang, Lei,Wang, Jian-Ping Asian Pacific Journal of Cancer Prevention 2016 Asian Pacific journal of cancer prevention Vol.17 No.2
Radiation proctitis is a common complication after radiotherapy for pelvic malignant tumors. This study was conducted to assess the efficacy of novel almagate enemas in hemorrhagic chronic radiation proctitis (CRP) and evaluate risk factors related to rectal deep ulcer or fistula secondary to CRP. All patients underwent a colonoscopy to confirm the diagnosis of CRP and symptoms were graded. Typical endoscopic and pathological images, risk factors, and quality of life were also recorded. A total of 59 patients were enrolled. Gynecological cancers composed 93.1% of the primary malignancies. Complete or obvious reduction of bleeding was observed in 90% (53/59) patients after almagate enema. The mean score of bleeding improved from 2.17 to 0.83 (P<0.001) after the enemas. The mean response time was 12 days. No adverse effects were found. Moreover, long-term successful rate in controlling bleeding was 69% and the quality of life was dramatically improved (P=0.001). The efficacy was equivalent to rectal sucralfate, but the almagate with its antacid properties acted more rapidly than sucralfate. Furthermore, we firstly found that moderate to severe anemia was the risk factor of CRP patients who developed rectal deep ulcer or fistulas (P= 0.015). We also found abnormal hyaline-like thick wall vessels, which revealed endarteritis obliterans and the fibrosis underlying this disease. These findings indicate that almagate enema is a novel effective, rapid and well-tolerated method for hemorrhagic CRP. Moderate to severe anemia is a risk factor for deep ulceration or fistula.
Qing-Yuan Xu,Xiao-Dong Li,Mang-Mang Lv 제어·로봇·시스템학회 2016 International Journal of Control, Automation, and Vol.14 No.2
Almost all of the existing research achievements in Iterative Learning Control (ILC) hitherto have beenfocused on One-Dimensional (1-D) dynamical systems. Few ILC researches are related to Two-Dimensional FornasiniMarchesina Model (2-D FMM). In this paper, an adaptive ILC approach is proposed for 2-D FMM systemwith non-repetitive reference trajectory under random boundary condition. The proposed adaptive ILC algorithmlearns the coefficient matrices of the system and updates the control input iteratively. As the times of iteration goesto infinity, the ILC tracking error outside the boundary tends to zero and all system signals keep bounded in thewhole ILC process. Illustrative examples are provided to verify the validity of the proposed adaptive ILC algorithm.
( Yuan Qing Hu ),( Jin Lin Huang ),( Qiu Chun Li ),( Yu Wei Shang ),( Fang Zhe Ren ),( Yang Jiao ),( Zhi Cheng Liu ),( Zhi Ming Pan ),( Xin An Jiao ) 한국미생물 · 생명공학회 2014 Journal of microbiology and biotechnology Vol.24 No.3
Campylobacter jejuni is a prevalent foodborne pathogen worldwide. Human infection by C. jejuni primarily arises from contaminated poultry meats. Genes expressed in vivo may play an important role in the pathogenicity of C. jejuni. We applied an immunoscreening method, in vivo-induced antigen technology (IVIAT), to identify in vivo-induced genes during human infection by C. jejuni. An inducible expression library of genomic proteins was constructed from sequenced C. jejuni NCTC 11168 and was then screened using adsorbed, pooled human sera obtained from clinical patients. We successfully identified 24 unique genes expressed in vivo. These genes were implicated in metabolism, molecular biosynthesis, genetic information processing, transport, and other processes. We selected six genes with different functions to compare their expression levels in vivo and in vitro using real-time RT-PCR. The results showed that the selected six genes were significantly upregulated in vivo but not in vitro. In short, these identified in vivo-induced genes may contribute to human infection of C. jejuni, some of which may be meaningful vaccine candidate antigens or diagnosis serologic markers for campylobacteriosis. IVIAT may present a significant and efficient method for understanding the pathogenicity mechanism of Campylobacter and for finding targets for its prevention and control.