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  • Author: Sławomir Stępień x
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Open access

Jakub Bernat and Sławomir Stępień

Induction motor analysis employing optimal torque predictor and massive conductor approach

This research presents a method for the simulation of the magneto-mechanical system dynamics taking motion and eddy currents into account. The major contribution of this work leans on the coupling the field-motion problem considering windings as the current forced massive conductors, modelling of the rotor motion composed of two conductive materials and the torque calculation employing the special optimal predictor combined with the modified Maxwell stress tensor method. The 3D model of the device is analysed by the time stepping finite element method. Mechanical motion of the rotor is determined by solving the second order motion equation. Both magnetic and mechanical equations are coupled in the iterative solving process. Presented method is verified by solving the TEAM Workshop Problem 30.

Open access

Jakub Bernat and Sławomir Stępień

Application of optimal current driver for the torque control of BLDC motor

This research presents the novel control strategy of the brushless DC motor. The optimal current driver is designed using Linear Quadratic Regulator and feedback linearization. Additionally, the current reshaping strategy is applied to control the motor torque. Thus, the torque controller is built based on the optimal current driver. The motor is simulated using the FEM analysis.

Open access

Sławomir Stępień and Justyna Grzesik

Abstract

The analysis of structural dependability of technical system, especially determining the change in dependability over time, requires knowledge on density function or the understanding of cumulative distribution function of components belonging to the structure. Based on previously registered data concerning component defect, it is relatively easy to establish the average uptime of component as well as the standard deviation for this time. However, defining distribution shape gives rise to some difficulties. Usually, we do not have the sufficient number of data at our disposal to verify the hypothesis regarding the distribution shape. Due to this fact, it is a common practice, depending on the case under consideration, to apply the function of defect density. However, the question arises: Does the incorrect determination of types of distributions of components leads to the big error of estimation results of dependability and system durability? This article will not respond to this question in whole, but one will conduct a comparison of calculation results for a few cases. The calculations were conducted for the exemplary technical system.

Open access

Sławomir Stępień and Justyna Grzesik

Streszczenie

Analiza niezawodności strukturalnej systemu technicznego, a zwłaszcza wyznaczenie zmiany niezawodności systemu w czasie, wymaga znajomości funkcji gęstości lub dystrybuant (zawodności) elementów wchodzących w skład struktury. Bazując na zarejestrowanych w przeszłości danych dotyczących uszkodzeń elementów, można w miarę łatwo wyznaczyć średni czas zdatnej pracy elementu oraz odchylenie standardowe dla tego czasu. Natomiast określenie postaci rozkładu nastręcza pewne trudności. Otóż z reguły nie dysponujemy dostateczną liczbą danych do weryfikacji hipotezy o postaci rozkładu. Z tego powodu powszechnie, w zależności od rozpatrywanego przypadku, zakłada się postać funkcji gęstości uszkodzeń. Powstaje pytanie: czy błędne określenie rodzajów rozkładów elementów powoduje duży błąd wyników oszacowania niezawodności i trwałości systemu? Niniejszy artykuł nie odpowie w pełni na to pytanie, ale zostanie dokonane porównanie wyników obliczeń dla kilku przypadków. Obliczenia zostały przeprowadzone dla przykładowego systemu technicznego.

Open access

Jakub Bernat, Jakub Kołota, Sławomir Stępień and Grzegorz Szymański

An inductance lookup table application for analysis of reluctance stepper motor model

This research presents a method of modeling and numerical simulation of a reluctance stepper motor using reduced finite-element time-stepping technique. In presented model, the circuit equations are reduced to non-stationary differential equations, i.e. the inductance mapping technique is used to find relationship between coil inductance and rotor position. A strongly coupled field-circuit model of the stepper motor is presented. In analyzed model the magnetostatic field partial differential equations are coupled with rotor motion equation and solved simultaneously in each iterative step. The nonlinearity problem is solved using Newton-Raphson method with spline approximation of the B-H curve.

Open access

J. Bernat, S. Stępień, A. Stranz, G. Szymański and J.K. Sykulski

Abstract

An optimal control theory based method is presented aiming at minimizing the energy delivered from source and the power loss in a stepper motor circuit. A linear quadratic current regulator with an infinite time horizon is employed and its appropriateness for this type of a problem explained. With the purpose of improving the accuracy of the control system, the self and mutual inductances of windings are calculated using a finite element model. The numerically computed results are verified experimentally.

Open access

Jakub Bernat, Jakub Kołota, Paulina Superczyńska and Sławomir Stępień

Abstract

A new structure to design observers for linear systems is presented in this work. The key step is the construction of two layers where the first consists of multiple observers and the second connects them providing the weighted estimation state. The main difficulty is to find a new feedback which is responsible for control weights. To define observation law, we rely on multi observers from the first layer. The proposed structure significantly improves the transient characteristics of the observation process, which is shown in illustrative examples.

Open access

Jakub Bernat, Jakub Kołota and Sławomir Stępień

Abstract

This research presents a 3D FE method for the simulation of the variable reluctance stepper motor dynamics. The proposed model is used to obtain the optimal minimum energy control law that minimizes the energy injected by the controller. The method is based on the strong coupling of field - circuit equations and extended to eddy current, motion and nonlinearity problem. The linearization technique for the coupled problem is presented. Also the lamination of the motor core is considered. In the paper the open - loop control problem is analyzed. The proposed model is validated by the comparison with measurements. Next, to demonstrate the effectiveness of the proposed optimal minimum energy control method is applied. In both cases, the examination of the variable reluctance stepper motor dynamics and the steel loss in the core is presented and compared