Bedrich Bednar

Single phase high-voltage matrix converter for traction drive with medium frequency transformer

This paper describes the realization variants of the new traction drive for AC-power system with high-voltage matrix converter and medium frequency transformer (i.e. MFT). These topologies allow minimizing the weight of the traction transformer in railroad vehicles. Special attention is given to serial connection of input single-phase high voltage matrix converters fed MFT transformers. The control method involving the reduction of MFT magnetic saturation has been discussed.

Traction Drive with MFT - Novel Control Strategy Based on Zero Vectors Insertion

Abstract This paper presents research motivated by industrial demand for special novel high voltage traction drive topology devoted to minimization of traction transformer weight against classical locomotives operates on both 25kV/50Hz and 15kV/16⅔Hz trolley voltages. The traction converter topology consists of: two single phase matrix converter + medium frequency transformer (MFT) + single phase voltage-source active rectifier. Measured results of steady state and selected transient states verifying of proper function of control algorithms. The new control strategy of traction converter based on zero vectors insertion has been proposed to smoothing taken trolley current.

The comparison of different variants of new traction drives with medium frequency transformer

This paper describes different variants of realization of new traction drive for AC- power system based on medium frequency transformer MFT. These topologies enable to minimize weight of traction transformer. Basic variants of input high voltage converter realization (using modular multilevel converter MMLC, indirect frequency converter with VSI, matrix converter or other direct frequency converter) have been compared. For these basic variants the modifications are solved (with different power circuits and with different control algorithms). Special attention is given to single-phase high voltage matrix converter with input filter used serial connection of capacitances (realized in laboratory).

Implementation of control algorithms for laboratory model of traction drive with high voltage matrix converters and medium frequency transformer

This paper deals with problematic of realization and implementation of control algorithms for laboratory model of electric drive of traction drive with medium frequency transformer MFT supplied by high voltage matrix converter MC. Output (from secondary winding from MFT) is rectified by active rectifier and it used form voltage source rectifier. Control algorithms for these parts are implemented into digital system with digital signal processor. Practical using of this electric drive is possibility of reducing of mass of traction transformer in locomotives for system 15kV/16.7Hz and 25kV/50Hz etc.

A novel ZCS single phase matrix converter for traction applications

This paper proposed a new ZCS single phase ac-ac matrix converter for the traction applications. The proposed soft switching matrix converter is enhanced with an auxiliary resonant circuit in order to achieve the zero current switching for main bidirectional switches of the matrix converter. The main advantage of this proposed topology is soft switching of matrix converter to achieve switching loses limitation. This paper describes the operation of the proposed matrix converter, simulation analysis and experimental validation of the prototype for 50V-16.7Hz-100W-400Hz.

Traction drive with medium-frequency transformer - Control strategy based on NULL vectors

This paper presents research motivated by industrial demand for special novel high voltage traction drive topology devoted to minimization of traction transformer weight against classical locomotives operates on both 25kV/50Hz and 15kV/162/3Hz trolley voltages. This paper deals with testing of whole traction converter prototype in configuration: two single phase matrix converter + medium frequency transformer + single phase voltage-source active rectifier in selected transient states and verifying of proper function of control algorithms. The new control of traction converter based on inserting zero vectors has been proposed to smooth taken trolley current.

Novel control strategy of traction converter with medium frequency transformer

This paper describes research into a novel control strategy of traction converter for the AC-Trolley Line with the medium frequency transformer (MFT). Attention is given to the problematics of finding a suitable control algorithm that will provide minimal magnetic saturation of MFT. This could be ensured by variable voltage pulses on MFT input defined by the control algorithm to ensure proper MFT saturation. Special attention is focused on the single-phase matrix converter topology and the best commutation solution. Two basic methods of switch control of the matrix converter are discussed. The first method requires the knowledge of the converter output current polarity and the second method assumes the knowledge of the input voltage polarity. In addition, the article describes the switching method in uncertain states - when the voltage or current cross zero. Moreover, the paper presents a new modular topology with several separate medium frequency transformers. The proposed algorithm is described and implemented in the experimental model.

Diagnostic tool for lithium and lead-acid battery

This paper describes difference between lead-acid and Li-Ion batteries. In this work will be measured charging and discharging Lead-Acid (Pb) and modern LiFePO4 accumulators by adjustable current or by pulse current. The charging characteristic is at first constant current and then constant voltage. System measures voltage, current and temperature and is able to log values to the PC.

Electric kart “FeLis” with LiFeYPO 4 batteries

This paper deals with the construction of the electric kart with LiFeYPO4. Electric kart is designed to replace conventional engine karts which are commonly used in karts rent business. It includes also descriptions of chosen parts like LiFeYPO4 batteries, MOSFET converter, sensors and electronics control system. The topology of electrical equipment is based on a CAN bus and allows further expansions by students projects. Today they, modern LiFeYPO4 are used as a power source of electric kart. This batteries allows rapid recuperation of the kinetic energy.

Traction drive with medium-frequency transformer - Smoothing trolley current by inserting zero vectors

This paper presents research motivated by industrial demand for special novel high voltage traction drive topology devoted to minimization of traction transformer weight against classical locomotives operates on both 25kV/50Hz and 15kV/162/3Hz trolley voltages. This paper deals with testing of whole traction converter prototype in configuration: two single phase matrix converter + medium frequency transformer + single phase voltage-source active rectifier in selected transient states and verifying of proper function of control algorithms. The new control of traction converter based on inserting zero vectors has been proposed to smooth taken trolley current.