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The purpose of this paper is to investigate the influence of back-EMF and current harmonics on position and speed estimation accuracy for single and dual three-phase (DTP) permanent magnet synchronous machines (PMSMs) with two fundamental-model-based sensorless control strategies which are widely utilized for AC machines, i.e. flux-linkage observer (FO) and simplified extended Kalman filter (EKF).

The effect of distorted back-EMF is studied for sensorless vector control of single three-phase PMSM. For the influence of current harmonics, unlike the existing literature where the current harmonics are deliberately injected, in this paper, sensorless switching-table-based direct torque control (ST-DTC) strategies for DTP-PMSM which inherently suffer from non-sinusoidal stator currents in addition to the distorted back-EMF, are investigated experimentally.

By employing the FO and simplified EKF-based sensorless vector control of single three-phase PMSM, it can be concluded that the rotor position estimation accuracy is less affected by the back-EMF harmonics when the simplified EKF method is utilized since it is less sensitive to such noises. When the influence of non-sinusoidal stator currents together with back-EMF harmonics is investigated for the conventional and modified ST-DTC of DTP-PMSM, it is indicated that the simplified EKF exhibits better position and speed estimation accuracy in both the conventional and modified ST-DTC strategies. In addition, its steady-state performance shows a slight superiority over that based on FO, in terms of flux and torque ripples, and THD of phase currents. For the dynamic performance, the estimated speed of simplified EKF shows less phase lag and fluctuations compared to that of FO.

This paper introduces the influence of back-EMF and current harmonics on sensorless control performance for single and DTP PMSMs. Detailed experimental results show that the simplified EKF exhibits better rotor position and speed estimation accuracy compared to that of FO due to its higher noise-rejection ability.

This study aims to design and implement a novel tilt integral sliding mode controller and observer for sensorless speed control of a permanent magnet synchronous motor (PMSM).

A control strategy combining the tilt integral derivative (TID) with sliding mode control (SMC) is proposed to determine the tilt integral sliding mode manifold. Using this manifold, tilt integral sliding mode controller (TISMC) and observer (TISMO) are designed. The stabilities are verified by using Lyapunov method. To prove the effectiveness and robustness of proposed methods, sensorless speed control of PMSM is performed for various operating conditions such as constant and variable speed references, load disturbance injection, parameter perturbation, whereas sensor noises are not taken into account. The performance of proposed method is compared with TID controller, proportional integral derivative controller and conventional SMO.

Simulation results demonstrate that TISMC and TISMO have better performance in all operating conditions. They are robust against parameter uncertainties and disturbances. TISM based sensorless control of PMSM is well guaranteed with superior performance.

The proposed method has not been tackled in the literature. By combining TID and SMC, novel tilt integral sliding manifold is presented and used in designing of the controller and observer. It is proven by Lyapunov method that errors converge to zero.

Wonders whether companies actually have employees best interests at heart across physical, mental and spiritual spheres. Posits that most organizations ignore their workforce – not even, in many cases, describing workers as assets! Describes many studies to back up this claim in theis work based on the 2002 Employment Research Unit Annual Conference, in Cardiff, Wales.

The purpose of this paper is to present a two-loop approach for velocity control of a permanent magnet synchronous motor (PMSM) under mechanical uncertainties.

The inner loop calculates the two-axis stator reference voltages through a feedback linearization method. The outer loop employs an RST control structure to compute the q-axis stator reference current. To increase the robustness of the proposed method, the RST controller parameters are adapted through a fractional order model reference adaptive system (FO-MRAS). The fractional order gradient and Lyapunov methods are utilized as adaptation mechanisms.

The effect of the fractional order derivative in the load disturbance rejection, transient response speed and the robustness is verified through computer simulations. The simulation results show the effectiveness of the proposed method against the external torque and mechanical parameters uncertainties.

The proposed FO-MRAS based on Lyapunov adaptation mechanism is proposed for the first time. Moreover, application of the FO-MRAS for velocity control of PMSM is presented for the first time.

DURING the past twelve years there have been six investigations of the spectral transmission of light through fog, mist, or liaze carried out in the United States. The conditions of the tests have been varied. Three of the researches were made with fog chambers; three with natural fogs. One was made with a path of only 1·9 m. (6·2 ft.); the longest path was 1,200 m. (3,900 ft.). One of the fogs was so light that a 1,000,000 candle‐power airway beacon could be seen 13 km. (8 miles); the densest would permit such a beacon to be seen only 0·03 km. (0·02 mile). One investigator scarcely covered the entire visible spectrum. Two included the infra‐red as far as 3·0 microns and 2·5 microns respectively, and the latter of these extended his work as far as 0·324 micron in the ultra‐violet. It is not surprising that curves based on data taken under such diverse conditions should show little resemblance to one another.

AIEST Les préparatifs du 30e Congrès AIEST du 14 au 20 septembre 1980 à l'Hôtel Son Vida, Palma de Mallorca, sont de façon que le programme définitif a pu être envoyé aux membres début juin, après un rappel de faire parvenir des contributions écrites touchant le sujet principal «Limites du développement touristique» pour être publié dans la publication du Congrès. Celle‐ci sera envoyée aux membres avant le Congrès.

Investigates the differences in protocols between arbitral tribunals and courts, with particular emphasis on US, Greek and English law. Gives examples of each country and its way of using the law in specific circumstances, and shows the variations therein. Sums up that arbitration is much the better way to gok as it avoids delays and expenses, plus the vexation/frustration of normal litigation. Concludes that the US and Greek constitutions and common law tradition in England appear to allow involved parties to choose their own judge, who can thus be an arbitrator. Discusses e‐commerce and speculates on this for the future.

Japanese materialistic behavior and consumption trends are examined by comparing age‐cohort differences between the Japanese “new breed” and “second baby‐boomer age‐cohorts”. Price perception, brand loyalty, and shopping‐information sources of the two age‐cohorts are also assessed. Results suggest that the Japanese new breed is more materialistic, sensitive to prestige, brand loyal, and likely to use media as their shopping information source as compared to second baby‐boomer. On the other hand, second baby‐boomers are less materialistic, value conscious, less brand loyal, and more likely to rely on word‐of‐mouth communication as their information sources as compared to the Japanese new breeds.

Through a survey of 200 employees working in five of the thirty establishments analysed in previous research about the microeconomic effects of reducing the working time (Cahier 25), the consequences on employees of such a reduction can be assessed; and relevant attitudes and aspirations better known.

EVERYONE today is busily engaged in devising new methods, bringing about economies in motions, and applying incentives, but is enough attention being paid to the maintenance mechanics, from the human aspect, in these applications of work study?