In this paper the Fault Tolerant (FT) vector controlled induction motor drive system is described and tested in various drive conditions. The influence of the rotor speed sensor faults on the ...properties of the analyzed drive are tested. Faults detection algorithms, based on different algorithms are developed and described. The results of the simulation carried out using the MATLAB/Sim Power System software are verified in experimental tests in Micro Lab Box DS 1202, in a wide range of motor speed changes. The proposed detection algorithms can be successfully applied in the Fault Tolerant Drive Systems (FTDS).
The use of wind power for generating electricity has experienced an uninterrupted and accelerating growth over last few decades and this growth is likely to continue. In order to enable even greater ...role of wind energy in power production it is necessary to increase the size and unit power of wind turbines. As wind turbines grow in size they are subjected to extreme loads and fatigue caused by nonuniform turbulent winds. Therefore, control algorithms that can assure load and fatigue reduction become a necessity. In this paper the individual pitch control for reduction of the periodic blade and hub loading is explored. To avoid problems related to the required blade loads measurements a method for their estimation based on other process variables is proposed. The performance of the individual pitch controller that uses such load estimations instead of measurements is tested and compared to the collective pitch control and the individual pitch control based on measured loads.
U radu je predložen funkcijski obzerver za sustave upravljanja gibanjem koji ostvaruje veću preciznost i manji šum estimacije u usporedbi s postojećim obzerverima. Obzerver estimira brzinu, ...akceleraciju i poremećaj korištenjem mjerenja ulazne struje, položaja te poznatih nominalnih parametara sustava. Znanstveni doprinos predloženog obzervera je funkcijska struktura koja omogućava intrinzičnu estimaciju i kompenzaciju nemjerljivih ulaznih veličina (kao što je poremećaj koji djeluje na sustav) korištenjem mjerenja ulazne struje. Eksperimentalni rezultati potvrđuju kako predloženi obzerver ostvaruje točniju estimaciju brzine, akceleracije i poremećaja u usporedbi s ostalim obzerverima drugog reda.
In GPS receivers, navigation bit allocation is performed throughout the process of signal tracking and detection. In the process of signal tracking, the locally generated signal must be synchronized ...with the received signal. The Costas phase-locked loop (PLL) behavior, which is often used for signal synchronization, is characterized by dominant tracking error sources. The resulting phase tracking errors are significant in the presence of weak signals, i.e. signals with the low signal-to-noise ratio (SNR). In order to improve the signal synchronization and enable signal tracking by the receiver, we here proposed the usage of a non-data-aided (NDA) phase estimator. Based on the practical processing of the GPS signals, it is shown that the applied NDA algorithm is more resistant to sudden changes in frequency (phase) of the input signal than the previously considered phase discriminator in the Costas PLL. Also, we have shown that the solution analyzed here exhibits more stable operation in signal tracking for a low SNR. / В GPS приемнике, распознавание навигационных битов реа- лизовано путем отслеживания и определения и обнаружения сиг- нала. В процессе отслеживания сигнала, локально генерируемый сигнал должен быть синхронизирован с входящим сигналом. Ха- рактеристикой фазового контура Costas, который традиционно используется для синхронизации сигналов, является подвержен- ность влиянию источников погрешностей. Ошибки в результа- тах по отслеживанию фазы существенны при слабом входном сигнале, например, для сигналов с малым отношением сигнал-по- мехи. Для улучшения синхронизации отслеживаемого сигнала со стороны приемника, мы рекомендуем использовать non-data-aided (NDA) фазовый компаратор.. Основываясь на практической обра- ботке GPS сигналов, можно сделать вывод, что применение ал- горитма NDA обеспечивает большую устойчивость к внезапным изменениям в частоте входного сигнала по сравнению с приме- няемыми в настоящее время фазовыми дискриминаторми с фазо- вым контуром Costas. Кроме того, на основании проведенного анализа было показано, что предложенное решение позволяет обеспечить стабильность работы, особенно для сигналов с низ- ким отношением сигнал-помехи. / Prepoznavanje navigaocionih bita u GPS prijemniku realizuje se kroz procese praćenja i detekcije signala. U procesu praćenja signala lokalno generisani signal mora biti sinhronizovan sa primljenim signalom. Karakteristika Costasove fazne petlje, koja se najčešće koristi za sinhronizaciju signala, jeste podložnost uticaju izvora grešaka. Rezultantne greške praćenja faze značajne su u prisustvu slabog ulaznog signala, kao, na primer, kod signala sa malim odnosom signal–šum. Radi pobolj- šanja sinhronizacije omogućavanja praćenja signala koji emituje strane prijemnika, predlažemo upotrebu non-data-aided (NDA) fazni estimator. Na osnovu praktične obrade GPS signala pokazano je da primena NDA algoritma omogućava veću otpornost na iznenadne promene frekvencije ulaznog signala u odnosu na do sada primenjivani fazni diskriminator u Costasovoj faznoj petlji praćenja. Na osnovu izvršene analize pokazano je, takođe, da predloženo rešenje omogućava stabilan rad, naročito kod signala sa malim odnosom signal–šum.
Problemi s upravljanjem mnogih procesa u industriji vezani su s nemogućnošću on-line mjerenja nekih važnih procesnih veličina. Ovaj se problem može u značajnoj mjeri riješiti estimacijom ovih ...teško-mjerljivih procesnih veličina. Estimator je pri tome odgovarajući matematički model procesa koji na temelju informacije o ostalim (lako-mjerljivim) procesnim veličinama procjenjuje trenutni iznos teško-mjerljive veličine. Budući da su procesi po prirodi promjenjivi, točnost estimacije zasnovane na modelu procesa izgra.enog na starim podacima u pravilu opada s vremenom. Kako bi se ovo izbjeglo, parametre modela procesa je potrebno kontinuirano prepodešavati kako bi model što bolje opisivao (trenutno) vladanje procesa. Ovisno o tipu matematičkog modela, za prepodešavanje njegovih parametara na raspolaganju je više metoda. Kao osnova estimatora teško-mjerljive veličine u radu se koristi PLSR model procesa, dok se njegovi parametri prepodešavaju na više načina – metodom pomičnog prozora, rekurzivnim NIPALS algoritmom, rekurzivnim kernel algoritmom te Just-in-Time Learning metodom. Svojstva navedenih metoda adaptacije PLSR modela procesa ispitana su na odabranom primjeru. Nadalje, metode adaptacije su analizirane i s obzirom na računalnu i memorijsku zahtjevnost.
This paper presents a new rotor flux estimation method for sensorless vector controlled squirrel-cage induction generators used in wind power applications. The proposed method is based on a ...phase-locked loop (PLL) and the orthogonality between the rotor flux space vector and its back electromotive force (EMF) space vector. Rotor flux is estimated using stator voltage equations without integrating the back EMF components in the stationary reference frame and the well-known difficulties with the implementation of pure integrators are thus avoided. Moreover, the proposed method ensures successful magnetization of a speed-sensorless squirrel-cage induction generator at nonzero speeds which makes it suitable for wind power applications. Experimental results on a 560 kW squirrel-cage induction generator are presented to confirm the effectiveness and the feasibility of the proposed method.
In this paper, we focus on the estimation of the rotor resistance to online tune the controllers in case of the Indirect Rotor Field Orientation Control (IRFOC) of Induction Machine (IM). The ...proposed method is based on the development of an adaptive Takagi-Sugeno (TS) fuzzy flux observer, described in a d-q synchronous rotating frame, to concurrently estimate the IM states and the rotor resistance variation. An investigation of the local pole placement is carried out in order to guarantee both the stability and specified observer dynamic performances. The observer's gains design is based on the resolution of sufficient conditions driven into LMIs terms (Linear Matrix Inequalities). Simulation and experimentation are carried out to show the effectiveness of the proposed results.
Vjetroagregati se obično postavljaju na udaljene, nepristupačne lokacije te je potrebno spriječiti nastanak kvarova da bi se povećala njihova ekonomska konkurentnost. Kvarovi elektromehaničkih ...dijelova generatora vjetroagregata česti su i vrlo skupi. U ovom radu predstavljen je koncept upravljanja vjetroagregatima s promjenjivom brzinom vrtnje i zakretom lopatica za slučaj identificiranog i okarakteriziranog oštećenja kaveza asinkronog generatora. Predložena je nadogradnja na postojeći algoritam upravljanja momentom zasnovana na njegovoj modulaciji s obzirom na položaj magnetskog toka generatora. Da bi se izbjeglo ili usporilo širenje napuknuća kaveza generatora, predložena je primjena regulacijskog kruga za zakret lopatica i u režimu rada vjetroagregata ispod nazivne brzine vrtnje. Predstavljena strategija upravljanja razvijena je uvažavajući mogućnost modularnog nadovezivanja na postojeće metode upravljanja već postavljenih vjetroagregata s ciljem produženja njihova životnog vijeka i povećanja proizvodnje energije. Razmatrani su i uvaženi aspekti vezani uz praktičnu izvedbu, kao što je estimacija varijabli korištenih u upravljačkom algoritmu i pripadajuće pogreške estimata, kao i nesimetrije uzrokovane nastankom kvara. U radu su dani simulacijski rezultati za slučaj vjetroagregata iz megavatne klase s dijagnosticiranim napuknućem kaveza rotora.
In this paper an Extended Kalman Filter (EKF) is used in order to estimate the real state of a humanoid robot (HRP-2 robot in our case study) using the combination of the information coming from the ...encoders (kinematics) and from the Inertial Measurement Unit (IMU). The integration of the kinematic information into the Kalman filtering process allows a good estimation of the attitude and reduces the complexity of the problem to the use of simple kinematic transformations, even considering the existence of accelerations and mechanical flexibilities in the robot. The EKF estimator presented here is an open solution directly applicable to any humanoid robot, which is the main contribution of our approach. Experimental results are given showing the good performance of the method.
In this paper, the problem of external sensors within bilateral teleoperation is addressed. We propose a Phase Locked Loop (PLL) αβ-tracker that presents an enhanced approach for position and ...velocity estimation. The proposed approach offers some advantages over the method presented in our previous research that was introduced to enable pseudo-sensorless teleoperation. Such approach applies PMLSM actuators with analog Hall sensors built in a motor housing. They allow obtaining sufficient position, velocity, and force information for teleoperation by a haptic interface. Furthermore, FPGA has been utilized for the implementation in order to achieve high control rate that was already introduced as a necessity in cutting edge performance systems. However, main advantages of the method presented in this paper is attributed to improved system performance due to the better signal-noise ratio and to enhanced flexibility of hardware resources consumption. Thus, high-performance bilateral control can be achieved. Such bilateral teleoperation with a dedicated haptic interface can significantly improve surgical robotics. The proposed approach was experimentally validated by the simple 1-DoF laboratory bilateral teleoperation system.
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