Speed -Sensorless Estimation And Position Control Of Induction Motors For Motion Control Applications

Thesis (Ph.D.) University of Alaska Fairbanks, 2006High performance sensorless position control of induction motors (IMs) calls for estimation and control schemes which offer solutions to parameter uncertainties as well as to difficulties involved with accurate flux and velocity estimation at very low and zero speed. In this thesis, novel control and estimation methods have been developed to address these challenges. The proposed estimation algorithms are designed to minimize estimation error in both transient and steady-state over a wide velocity range, including very low and persistent zero speed operation. To this aim, initially single Extended Kalman Filter (EKF) algorithms are designed to estimate the flux, load torque, and velocity, as well as the rotor, Rr' or stator, Rs resistances. The temperature and frequency related variations of these parameters are well-known challenges in the estimation and control of IMs, and are subject to ongoing research. To further improve estimation and control performance in this thesis, a novel EKF approach is also developed which can achieve the simultaneous estimation of R r' and Rs for the first time in the sensorless IM control literature. The so-called Switching and Braided EKF algorithms are tested through experiments conducted under challenging parameter variations over a wide speed range, including under persistent operation at zero speed. Finally, in this thesis, a sensorless position control method is also designed using a new sliding mode controller (SMC) with reduced chattering. The results obtained with the proposed control and estimation schemes appear to be very compatible and many times superior to existing literature results for sensorless control of IMs in the very low and zero speed range. The developed estimation and control schemes could also be used with a variety of the sensorless speed and position control applications, which are challenged by a high number of parameter uncertainties

ESTABLISHMENT OF AN FPGA-BASED REAL-TIME IM EXPERIMENTAL SETUP AND ONLINE IM MODEL VERIFICATION

In this study, Serial Peripheral Interface (SPI) communication between the ADS 8568 EVM-PDK (Evolution Performance Development Kit) Analog to Digital Converter (ADC) developed by Texas Instrument and Xilinx XC5VLX110T FPGA board is implemented in order to verify Induction Motor (IM) model in real-time. Analog datas obtained from the voltage, current and torque transducers are converted to digital datas by ADC and read with FPGA simultaneously in real-time. Thus, the αβ- stator stationary axis components of the stator voltage ( and ) and αβ- axis components of the stator current ( and ) are calculated by Clarke transformation. The load torque  is obtained by passing the measured signals from the torque transducer through the low-pass filter which is implemented on the FPGA using 64-bit double floating number format. In addition, the signals obtained from the incremental encoder are read by the FPGA after the voltage level shifting with 74LS245P Integrated Circuit (IC), so that mechanical speed  (or ) of the rotor can be measured. All measurement algorithms except for the lowpass filter constructed for load torque measurement are implemented with VHDL by using 32-bit single floating numbers. The real-time verification of the rotor flux-based IM model is performed offline before it is implemented on FPGA by using the stator voltages, currents and load torque measured from the IM by using the simultaneous measurement unit in real-time. Thus, an FPGA-based real-time open-loop experimental setup of IM is established for the future works about the estimator/observer based speed-sensorless control of IMs

Von Willebrand’s disease diagnosed after hemorrhage following hysteroscopic myoma resection and endometrial band excision

Von Willebrand factor, the largest human plasma protein, is an adhesive multimeric glycoprotein that mediates platelet adhesion to both the subendothelial matrix and endothelial surfaces and acts as a carrier for coagulation factor VIII in the circulation. Von Willebrand disease (vWD) is the most common inherited bleeding condition that involves extended or excessive bleeding and is caused by the deficiency or defect of vWF. In this case report, we present vWD diagnosed after hemorrhage following hysteroscopic myoma resection and endometrial band excision. The importance of a detailed medical history is emphasized as even health care workers cannot spontaneously give this information. Further tests are recommended in patients who have a history of prolonged bleeding as bleeding time and other routine coagulation tests done preoperatively cannot always make a definite diagnosis

The associations between university students’ transformational leadership characteristics and dysfunctional limitedness perceptions

AbstractThe aim of this study was to explore associations between transformational leadership and limitedness schemas of university students. Data were collected from 66 male (34.2%) and 127 females (65.8%), a total of 193 university students. The minimum age was 17 and the maximum age was 23. The mean age of the sample was 19.62 years with a standard deviation of 1.21. The results reveal that females have higher scores than males with regard to transformational leadership characteristics. Comparison of the differences between male and female subjects in terms of limitedness orientation showed that males reported higher scores than females on limitedness schemas. In addition, limitedness about relations and limitedness about the world were significantly associated with transactional leadership and a laissez-faire philosophy, but connections of dysfunctional limitedness schemas with transformational leadership were not significant

Determination by Landsat Satellite Imagery to Local Scales in Land and Pollution Monitoring: A Case of Buyuk Melen Watershed (Turkey)

Buyuk Melen Watershed provides drinking water from the Western Black Sea region to Istanbul province, which Buyuk and Kucuk Melen rivers, Asar, Ugur and Aksu rivers. Many settlement areas, fertilized agricultural lands, industrial plants and solid/liquid waste dumping areas have present in Melen watershed, causing substantial pollution problems. Melen watershed has been at a serious risk of pollution that a lot of settlement areas, agricultural lands, industrial facilities, and solid and liquid waste. In this study, LANDSAT satellite data was used to monitor the status of this area on the potential of the region studied. In the watershed change of 1987, 2001, 2006 and 2010 and also supported by satellite data. However, contaminants in the watershed discharges to the inner parts as shown from the satellite data have also been observed that the increase in pollution

True knot of the umbilical cord in advanced weeks of pregnancy: a case report

True knot of the umbilical cord is a very rare condition. Usually a true knot is noticed after delivery and does not lead to problems. It is relatively less common than the other umbilical cord anomalies. Most authors agree that there is little that can be done to prevent fetal death in undiagnosed true knot. In our case, the patient gave birth to a healthy male baby weighing 2700 grams by normal vaginal delivery after an ultrasound was suggestive of intrauterine growth restriction (IUGR). The baby’s Apgar scores were 8 at one minute and 9 at five minutes. The umbilical cord measured 125 cm and contained two loose true knots. It was surprising that the baby could survive until term with these two knots and we hypothesize that this was the cause of the IUGR. Our case was interesting as neither neurologic sequela nor intrauterine death developed, despite two true umbilical cord knots

True knot of the umbilical cord in advanced weeks of pregnancy: a case report

True knot of the umbilical cord is a very rare condition. Usually a true knot is noticed after delivery and does not lead to problems. It is relatively less common than the other umbilical cord anomalies. Most authors agree that there is little that can be done to prevent fetal death in undiagnosed true knot. In our case, the patient gave birth to a healthy male baby weighing 2700 grams by normal vaginal delivery after an ultrasound was suggestive of intrauterine growth restriction (IUGR). The baby’s Apgar scores were 8 at one minute and 9 at five minutes. The umbilical cord measured 125 cm and contained two loose true knots. It was surprising that the baby could survive until term with these two knots and we hypothesize that this was the cause of the IUGR. Our case was interesting as neither neurologic sequela nor intrauterine death developed, despite two true umbilical cord knots

Speed sensorless direct vector control of the IM

Bu çalışmada, Sincap Kafesli Asenkron Motorların (SKASM’lerin) algılayıcısız kontrolünde başarımı olumsuz yönde etkileyen modele ait elektriksel ve mekanik yana ilişkin parametre belirsizliklerini çözmek üzere Genişletilmiş Kalman Filtresi (GKF) tabanlı gözlemleyici algoritmaları tasarlanarak gerçeklenmiştir. Doğrudan vektör kontrol sistemi ya da vektör kontrollü a.a sürücüsü ile başarımları test edilen bu algoritmalar ile herhangi yüksek frekanslı bir işaret eklemeksizin ve başlangıç değerleri bilinmediği varsayımıyla algılayıcısız kontrol için gerekli tüm durumlar, sabit sürtünme –viskoz– terimini de içeren yük momenti ve değeri bilinmeyen rotor direnci eş zamanlı olarak kestirilebilmiştir. Benzetim/deney sonuçları önerilen yöntemlerin oldukça etkin ve dayanıklı olduğunu göstermiştir. Bu yönleriyle, literatürde bilinen ilk çalışmadır.Anahtar Kelimeler: Genişletilmiş Kalman filtresi, gözlemleyici, kestirici, hız algılayıcısız vektör kontrol, asenkron motor.This paper offers a solution to the performance deteriorating effect of uncertainties in the sensorless control of induction motors (IMs). The major contribution of the study is the development and implementation of a Extended Kalman Filter (EKF) algorithms that take electrical and mechanical uncertainties into account. Also, unlike previous EKF based estimation studies taking the angular velocity, wm, into consideration as a constant parameter, in this study, wm, is estimated as a state with the utilization of the equation of motion. In this regard, this is the first known study to estimate the mechanical uncertainties together with the estimation of the rotor resistance, without injecting high frequency signals. The EKF algorithms also estimate the rotor flux, angular velocity and stator currents with no apriori knowledge on the states and initial values taken as zero. Experiments performed under unknown load torque and with rotor resistance variations up to twice the rated value, demonstrate the good performance and robustness of the estimation methods. The algorithms also estimate the mechanical uncertainties as a constant state to capture the unknown viscous and Coulomb friction in steady state, therefore, could be used to improve the performance of the velocity or position control of IM's, if utilized in combination with a compensation scheme.Keywords: Extended Kalman filter, observer, estimator, speed sensorless vector control, induction motor

Coexistence of cervico-thoracic extradural en-plaque meningioma with multiple intracranial meningiomas

Meningioma is one of the most common tumors in the spinal cord. Extradural and en-plaque variety of meningioma occur less frequently. A 47-year-old woman is presented with radiculopathy signs. Magnetic resonance imaging revealed a lesion from C6 through T3 vertebral levels compressing the cord both anteriorly and posteriorly. Subtotally excision was performed and histopathologic signs showed transitional type of meningioma (WHO Grade 1). Post operatively, she had good neurological recovery. Intraoperative findings point out that the en-plaque meningioma was pure extradural. Twelve cases of pure extradural en-plaque meningioma have been reported in the literature. Besides, to the best our knowledge coexistence of “en plaque” spinal epidural meningioma with meningiomas in cranial cavity has not been reported. Complete resection is mandatory to prevent recurrence. Moreover, it is considerably difficult to remove the parts of tumor over anterior of the dura without complication

Superconformal symmetry and maximal supergravity in various dimensions

In this paper we explore the relation between conformal superalgebras with 64 supercharges and maximal supergravity theories in three, four and six dimensions using twistorial oscillator techniques. The massless fields of N=8 supergravity in four dimensions were shown to fit into a CPT-self-conjugate doubleton supermultiplet of the conformal superalgebra SU(2,2|8) a long time ago. We show that the fields of maximal supergravity in three dimensions can similarly be fitted into the super singleton multiplet of the conformal superalgebra OSp(16|4,R), which is related to the doubleton supermultiplet of SU(2,2|8) by dimensional reduction. Moreover, we construct the ultra-short supermultiplet of the six-dimensional conformal superalgebra OSp(8*|8) and show that its component fields can be organized in an on-shell superfield. The ultra-short OSp(8*|8) multiplet reduces to the doubleton supermultiplet of SU(2,2|8) upon dimensional reduction. We discuss the possibility of a chiral maximal (4,0) six-dimensional supergravity theory with USp(8) R-symmetry that reduces to maximal supergravity in four dimensions and is different from six-dimensional (2,2) maximal supergravity, whose fields cannot be fitted into a unitary supermultiplet of a simple conformal superalgebra. Such an interacting theory would be the gravitational analog of the (2,0) theory.Comment: 54 pages, PDFLaTeX, Section 5 and several references added. Version accepted for publication in JHE