TRANSACTIONS ON ELECTRICAL ENGINEERING

ISSN 1805-3386

September 23, 2017






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2012 No.1

Digital Current Mode Control for Buck-Converter Based on Average Inductor Current Measurement

Milanovič, M., Truntič, M., Konjedic, T.

This paper introduces a digitally performed current mode and voltage control for the dc-dc step down converter based on voltage to frequency converter where the average values of inductor current and output voltage are obtained. These current and voltage measurement are realized by the voltage control oscillator (VCO) and counters (digital integrator). Such an approach enables full digitalization of current and voltage control loops.

 

Keywords: DC-DCconverters, converter control, current control

 

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MRAS-Type Speed and Flux Estimator with Additional Adaptation Mechanism for the Induction Motor Drive

Tarchala, G., Orlowska-Kowalska, T., Dybkowski, M.

This paper deals with a novel Model Reference Adaptive System (MRAS) estimator of the rotor flux and speed reconstruction for induction motor drive. The proposed estimator is based directly on the mathematical model of the induction motor. In comparison with existing methods the additional variable is introduced, which has to partly reduce the estimator sensitivity to the rotor time constant changes. Chosen simulation tests of the proposed solution are presented.

 

Keywords: Induction motor, sensorless drives, state estimators, MRAS techniques

 

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Traction Drive with PMSM: Frequency Characteristics Measurement

Glasberger, T., Peroutka, Z., Janda, M., Majorszký, J.

This paper describes a new method for measurement of frequency characteristics of ac traction drives. It helps to find dangerous resonant frequencies of the traction drive supplied from dc electrification system and it allows finding danger oscillations of the dc-link LC filter. Presented method has been verified a drive with a surface mounted PMSM controlled by DTC. The results prove the drive under constant taken power amplifies LC filter oscillations. We have proposed an improvement of the drive control in order to protect the drive against this phenomenon. The behaviour of improved DTC control has been analyzed by experiments made on the laboratory model of the traction drive of rated power of 10 kW.

 

Keywords: traction, measurement, permanent magnet motors

 

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Motor Drive Stabilization in its Chaotic Region

Stumpf, P., Nagy, I.

The paper is concerned with the stability analysis and the control of chaos in a permanent magnet dc drive system. The stability analysis is based on the eigenvalues of the Jacobian matrix of the Poincare Map Function (PMF). Using the auxiliary state vector, the Jacobian matrix can be determined without the derivation of the PMF. A compensating ramp signal is used to avoid bifurcation. The slope of the ramp signal is also determined by the auxiliary state vector. The results are verified by computer simulations in the time domain.

 

Keywords: DC machines, Speed Control, Nonlinear Dynamics

 

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Resonant DC-DC Converter for Photovoltaic Systems

Eötvös, E., Dudrik, J., Béreš, T.

This paper describes a step-up DC-DC converter, which main task is to increase the voltage from a low level drawn from a photovoltaic (PV) panel, to a high controlled level for connected inverter. The converter also provides an electrical isolation of PV panels from the grid. In the DC-DC converter a resonant LLC topology is used. The converter operates at high switching frequency to achieve small size of the power transformer. The main benefit of this converter is zero-voltage switching (ZVS) of primary MOSFETs and zero-current switching (ZCS) of rectifier diodes over the entire operating range. Advantage of used topology is that the converter can be controlled by a simple 8bit microcontroller (MCU). A laboratory model with maximum 95.5% efficiency was built to verify properties of the LLC resonant DC-DC converter.

 

Keywords: LLC resonant converter, zero-voltage switching (ZVS), zero-current switching (ZCS)

 

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Active Elimination of Low-Frequency Harmonics of Traction Current-Source Active Rectifier

Michalík, J., Molnár, J., Peroutka, Z.

In this paper, the new control approach in active suppression of low-frequency disturbances in trolley-wire current using resonant (R) controllers is presented. It is dedicated for a single-phase active current-source rectifier (ACSR) developed within the research into a new generation of main traction converters employing medium-frequency transformer dedicated for suburban units operating on both ac electrification systems of 25kV/50 Hz and 15kV/16,7 Hz. Proper function of proposed control strategy with a new compensative principle has been verified by simulations and large experimental study made on designed small-scale prototype of ACSR of rated power of 7kVA.

 

Keywords: converter control, modulation strategies, power factor correction, single phase systems

 

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