Jan Zak

Compensation of low-frequency disturbances for traction converter with medium-frequency transformer for multi-system suburban units

The presented research deals with a new configuration of a main traction converter with medium-frequency transformer which is intended for modern multisystem suburban units and locomotives. This paper exactly introduces proposed control of primary voltage source active rectifiers with direct control of trolley-wire current and active damping of low-frequency disturbances at the converter ac side. The theoretical conclusions are verified by simulations and experiments made on developed small-scale laboratory prototype of traction converter of rated power of 12kW.

Control strategy of active power filter with adaptive FIR filter-based and DFT-based reference estimation

This paper focuses on comparison of adaptive and predictive FIR filter-based and discrete Fourier transform-based current reference estimation for active power filters. Both estimation methods as well as a control algorithm of the single-phase shunt-type active power filter which is able to suppress harmonic currents drawn by nonlinear load are discussed. Performance and filtering quality are presented by experimental results made on a designed APF laboratory prototype.

Control of primary voltage-source active rectifiers of traction converter with medium-frequency transformer: Advantages of control unit combining DSP and FPGA

This paper investigates traction converter with medium-frequency transformer intended for modern suburban units. It describes proposed control of primary voltage-source active rectifiers with PR-controller completed by harmonic compensator. Developed control was implemented in control unit combining DSP and FPGA. Proposed control system properties are analyzed by experiments made on developed down-scale traction converter.

Elimination of dead-time effect causing current distortion of single-phase power converters

This paper describes constraints created by dead-times in single-phase voltage-source inverters working with medium and high switching frequencies (over thousands of Hertz). The dead-times cause distortion of a current at a converter ac side which is not acceptable especially in applications requiring high-precision current control. The control of voltage-source converter presented in this paper uses vector control in Cartesian coordinates which is offers very good dynamic properties. However, it is not able to naturally compensate the dead-time effects. Therefore, we complete this control by dead-time compensation block mitigating the unwanted distortion of converter ac current caused by dead-time effects using a nonlinear function generator. The behaviour of inverter control with proposed dead-time compensation and without compensation is reported in this paper.

Laboratory prototype of traction converter with medium-frequency transformer: Master control and diagnostic unit

This contribution deals with the prototype of the main traction converter with medium frequency transformer for AC trolley wire fed locomotives. The attention is paid to the new master control and diagnostic unit. The designed master control unit has been programmed in the LabView development environment. This master unit ensures a human interface between a user and a digital signal processor. In this case, the master unit makes possible both control and diagnostic operations of the laboratory prototype of the traction converter. The master unit was tested by experiments performed on designed traction converter prototype of rated power of 12kW.

Time-based and frequency-based fundamental grid current estimation for single-phase active power filters

This paper deals with two estimators designed for real-time fundamental component grid current extraction which is a critical task in control of single-phase active power filters (APF). An adaptive and predictive FIR filter and discrete Fourier transform have been employed in order to achieve proper APF operation, and thus, high-quality compensation of a distorted current drawn by a nonlinear load. Besides design and comparison of both implemented methods, the single-phase APF as well as its control algorithm based on direct current control are discussed in this paper. The compensation of both harmonic currents and reactive power, respectively, is presented by experimental results performed on designed laboratory APF prototype.

DSP-based control of main traction converter containing medium-frequency transformer

This paper deals with a main traction converter containing a medium-frequency transformer determined primarily for a new generation of suburban units operating on both ac electrification systems of 15 kV/ 16.7 Hz and 25 kV/ 50 Hz. The paper introduces proposed control of primary (trolley-wire connected) converters based on a predictive mathematical model and proportional-resonant controllers. A control strategy of secondary voltage source active rectifiers based on hysteresis current control is optimized for effective power flow through a medium-frequency transformer. The theoretical findings of this research are verified by experiments made on developed small-scale converter prototype of rated power of 12 kW.

Educational project of an interactive model of a photovoltaic power plant

This paper introduces the concept of a micro-photovoltaic power plant which we are developing mainly for educational purposes. It is presented a unique system design of the power plant combining state-of-the-art technologies from various branches of electrical engineering into a functional prototype suitable for both educational and research activities. Hardware description, software features and respective control system of the micro-photovoltaic power plant prototype are described in this paper.