Permanent Magnet Synchronous Motors are Globally Asymptotically Stabilizable with PI Current Control

This note shows that the industry standard desired equilibrium for permanent magnet synchronous motors (i.e., maximum torque per Ampere) can be globally asymptotically stabilized with a PI control around the current errors, provided some viscous friction (possibly small) is present in the rotor dynamics and the proportional gain of the PI is suitably chosen. Instrumental to establish this surprising result is the proof that the map from voltages to currents of the incremental model of the motor satisfies some passivity properties. The analysis relies on basic Lyapunov theory making the result available to a wide audience

Predictors of Mid-Term AVNeo Insufficiency

ABSTRACT Introduction: Aortic stenosis (AS) is the most common valvular heart disease and the most common indication for aortic valve replacement in adults. Aortic valve neocuspidization (AVNeo) with fixed autologous pericardium, also known as the Ozaki procedure, is a possible alternative treatment of AS. Autopericardial valves save the dynamics and physiological anatomy of the aortic root, however, the service life of autopericardial leaflets is limited. There is no data about factors that may influence the development of AVNeo insufficiency. Here, we assessed the effect of autopericardial leaflet symmetry on the development of aortic insufficiency after Ozaki procedure. Methods: This study included 381 patients with AS who underwent Ozaki procedure. Patients were divided into group 1 (171 patients with symmetric aortic root) and group 2 (210 patients with asymmetric aortic root). Results: The maximum observation period was up to 65 months. Sixteen cases of aortic insufficiency were detected in group 1, and 33 cases were detected in group 2. Based on the results of Cox regression, the predictors of aortic insufficiency in the late postoperative period are age and asymmetry of neocusps. According to results of Kaplan–Meier analysis, insufficiency of AVNeo in the maximum follow-up period after surgical correction of AS for group 1 patients was significantly lower than for group 2 patients (P=0.006). Conclusion: Asymmetric neocusps increase the risk of aortic insufficiency in the mid-term period after Ozaki procedure. And the older the patients at the time of surgery, the less likely they develop AVNeo insufficiency

Coronary-Coronary Bypass Grafting

This work is devoted to the original method of myocardial revascularization—coronary-coronary bypass grafting. Coronary artery bypass grafting can be considered as an independent method in an exceptional case or as an addition to the standard coronary artery bypass grafting technique. This paper presents the technique for performing CCBG, as well as the early and long-term results of the main studies. Attention is also paid to the advantages and disadvantages of this method from the standpoint of physiology and physics

Involvement of students and postgraduates into megagrant laboratory under supervision of leading scientist Romeo Ortega at ITMO University

In 2010 the Government of the Russian Federation established particularly large grants aimed to attract world-renowned scientists, including compatriots living abroad, to Russian scientific and educational centres. These grants, known as Megagrants, ensure the creation of research teams that can compete with the leading world laboratories and achieve world-class scientific results. Involvement of young Russian scientists in the projects became one of the main Megagrant features: half of the participants are people under the age of 35 years. Founded as a part of this project in ITMO University the laboratory “Nonlinear Adaptive Control Systems” under Romeo Ortega’s leadership is described in the paper. This laboratory was created at the Department of Control Systems and Informatics. The priority of the laboratory is the preparation and formation of a stable team able to conduct advanced research in the field of nonlinear, adaptive and robust control of various technical objects

Transition of the Russian federation to new educational standard: independent work of students as a factor in the quality of educational process

The paper is devoted to changes in the organization of independent work of students. These changes are associated with transition of the Russian Federation to new educational standards. In this regard, systemically-active approach to educational process, which is also called competence-based approach, comes to replace the knowledge-based model of education. Independent work of students as one of the main components of the competence-based approach is aimed not only at achieving of educational goals, but mainly on the formation of personal qualities of the future specialist - self-knowledge, self-development and self-realization. These qualities form a new competent person who meets the requirements of the labor market. The research includes consideration of issues such as organization, planning, monitoring methods of self-dependent student work taking into account the requirements of the educational standard

Involvement of students and postgraduates into megagrant laboratory under supervision of leading scientist Romeo Ortega at ITMO University*

In 2010 the Government of the Russian Federation established particularly large grants aimed to attract world-renowned scientists, including compatriots living abroad, to Russian scientific and educational centres. These grants, known as Megagrants, ensure the creation of research teams that can compete with the leading world laboratories and achieve world-class scientific results. Involvement of young Russian scientists in the projects became one of the main Megagrant features: half of the participants are people under the age of 35 years. Founded as a part of this project in ITMO University the laboratory “Nonlinear Adaptive Control Systems” under Romeo Ortega’s leadership is described in the paper. This laboratory was created at the Department of Control Systems and Informatics. The priority of the laboratory is the preparation and formation of a stable team able to conduct advanced research in the field of nonlinear, adaptive and robust control of various technical objects

Transition of the Russian federation to new educational standard: independent work of students as a factor in the quality of educational process*

The paper is devoted to changes in the organization of independent work of students. These changes are associated with transition of the Russian Federation to new educational standards. In this regard, systemically-active approach to educational process, which is also called competence-based approach, comes to replace the knowledge-based model of education. Independent work of students as one of the main components of the competence-based approach is aimed not only at achieving of educational goals, but mainly on the formation of personal qualities of the future specialist - self-knowledge, self-development and self-realization. These qualities form a new competent person who meets the requirements of the labor market. The research includes consideration of issues such as organization, planning, monitoring methods of self-dependent student work taking into account the requirements of the educational standard

Position observer for salient PMSM with measured speed

International audienceThis paper addresses the problem of position estimation for salient permanent magnet synchronous motors (PMSMs). It is assumed that stator currents and voltages and rotor speed are measurable signals. Two extensions of the position observer are presented - the first one is based on a standard gradient estimator and the second observer uses recently proposed the dynamic regression extension and mixing (DREM) procedure for adaptive estimation of parameters. Both position observers provide global boundness of all signals. In contrast to standard gradient approach which requires persistent excitation (PE) condition of the regressor, DREM estimator ensures parameter convergence if the regressor is not square-integrable. If the regressor is PE the DREM-based observer (like the one with gradient estimator) ensures exponential convergence of position error to zero value. Simulation results demonstrate higher open loop performance of the position observer with DREM estimator - its transient behaviour is less oscillatory with a faster convergence rate compared to observer with gradient algorithm. Also simulations show that both observers possess some robust properties with respect to parameter uncertainty of the motor

Sensorless Control of Permanent Magnet Synchronous Motors based on Finite-Time Robust Flux Observer

International audienceA sensorless control algorithm is developed based on novel finite-time robust flux observer for the non-salient permanent magnet synchronous motor (PMSM). Total flux equality and motor model are used to find the linear regression-like model with respect to the flux. Applying dynamic regressor extension and mixing method, we obtain two independent scalar equations and construct a finite-time flux observer. The flux estimate is used to reconstruct the rotor position and velocity with well-known trigonometric relation and phase-locked loop observer, respectively. To complete a sensorless control design, we pass these estimates to standard field orient control. The efficiency and robustness of the proposed approach are demonstrated through the set of numerical simulations

A robust nonlinear position observer for synchronous motors with relaxed excitation conditions

International audienceA robust, nonlinear and globally convergent rotor position observer for surface-mounted permanent magnet synchronous motors was recently proposed by the authors. The key feature of this observer is that it requires only the knowledge of the motor's resistance and inductance. Using some particular properties of the mathematical model it is shown that the problem of state observation can be translated into one of estimation of two constant parameters, which is carried out with a standard gradient algorithm. In this work, we propose to replace this estimator with a new one called dynamic regressor extension and mixing, which has the following advantages with respect to gradient estimators: (1) the stringent persistence of excitation (PE) condition of the regressor is not necessary to ensure parameter convergence; (2) the latter is guaranteed requiring instead a non-square-integrability condition that has a clear physical meaning in terms of signal energy; (3) if the regressor is PE, the new observer (like the old one) ensures convergence is exponential, entailing some robustness properties to the observer; (4) the new estimator includes an additional filter that constitutes an additional degree of freedom to satisfy the non-square integrability condition. Realistic simulation results show significant performance improvement of the position observer using the new parameter estimator, with a less oscillatory behaviour and a faster convergence speed