Juhan Laugis

Development of 50-kW Isolated DC/DC Converter with High-Voltage IGBTs

The 6.5 kV insulated gate bipolar transistor (IGBT) is a new promising power device for high-voltage high-power applications. Due to its increased voltage blocking capability, the new HV IGBT can serve as a good replacement for GTO and IGCT thyristors in medium or medium-to-high power applications. One of its general application fields is railway traction. The paper discusses design and development considerations of the 50-kW auxiliary power supply to be used in 3.0 kV DC commuter trains. Focus is on the implementation of 6.5 kV IGBTs in the primary inverter of APS to improve overall power density, system integrity as well as reliability of the whole system. For instance, topology selection, analysis and simulation of functional blocks of a converter for different operation points are described. A prototype of half-bridge isolated DC/DC converter with two 6.5 kV 200 A IGBT transistors was designed and built. Some design considerations are specified in the paper.

Development of Auxiliary Power Supplies for the 3.0 kV DC Rolling Stock

The paper discusses design and development problems of auxiliary power supplies (APS) with output powers up to 100 kW to be used in 3.0 kV DC commuter trains. Focus is on the implementation of 6.5 kV IGBTs in IHVM of APS. Using single 6.5 kV IGBT module instead of several series-connected IGBTs or even converters helps to achieve more reliable, efficient, compact and lightweight design than ever. For the APS with output power up to 100 kW, the simple half-bridge topology and two 200 A 6.5 kV IGBTs (one for the TOP and one for the BOT switch) it is sufficient to fulfill all the design requirements. Given paper generally deals with topology selection, analysis of switch losses and cooling of HV IGBT as well as with control and protection of the new power supply. Some generalizations and practical considerations are given.

Middle-frequency isolation transformer design issues for the high-voltage DC/DC converter

This paper addresses some specific design issues encountered in the development of isolation transformers for the rolling stock auxiliary power supply (APS). The optimal transformer design rule of the copper and core loss equalization will not work for middle-frequency (500...3000 Hz) high-power transformers. Main attention here must be paid to selection of the proper material for the magnetic core and to define an optimal operating flux density to minimize the dimensions and to improve operability and efficiency of the transformer, respectively. In the isolation transformers design for the APS converters with high input voltage and load variations, a threat related to magnetic core saturation caused by transient conditions should be considered. These and some other specific design issues (minimization of leakage inductance and parasitic capacitances, high-voltage isolation, etc.) make the design of such devices very challenging.

Comparison of university level study methods and laboratory equipment for teaching of electrical drives

The paper deals with teaching problems on the university level. Integration of different study fields like mechatronics, electrical drives and industry automation is under discussion. The article compares different classical and modern study methods and laboratory equipment: classical lecture and laboratory courses, virtual Internet-based training and virtual laboratories, project-based learning by doing, self-made stands for experiments, standardized teaching laboratory systems, and industrial component-based laboratories

Object-Oriented Electric Drive Development Technology

The paper introduces an effective project management system. The package eDrive has been developed to support the major stages in electric drives design process. This toolbox includes the database of motors, power converters, and gears, the object-oriented simulation software, the signal generation module, as well as the suitable user interface. The system provides dc and ac drives development, tuning, and investigation with current, speed, and position adjustment in open loop and closed-loop modes.

Evaluation of different loss calculation methods for high-voltage IGBT-s under small load conditions

This paper focuses on the evaluation of the calculated and measured values of high-voltage 6.5 kV IGBT module losses, used in mid-power applications under low load conditions. The values of the losses were calculated by use of widely known equations and IPOSIM 6.0 software. The experimental setup was based on a high-voltage half-bridge isolated DC/DC converter. Comparison of calculation and experimental results shows that the dynamic losses on higher switching frequencies are smaller than those calculated and that the IPOSIM software is relatively accurate. This knowledge helps developers to avoid overestimation of the losses and allows us to construct more compact power electronics applications with much higher switching frequencies.

An improved high‐voltage IGBT‐based half‐bridge DC/DC converter for railway applications

Purpose – The paper presents the findings of an R&D project connected to the development of 50 kW auxiliary power supply for the high‐voltage DC‐fed commuter trains. The aim was to introduce a new generation power converter utilizing high‐voltage insulated gate bibolar transistor (IGBT) modules, which can outpace the predecessors in terms of efficiency and power density, i.e. to provide more power for smaller volumetric space.Design/methodology/approach – For development of the proposed converter, mathematical analysis and computer simulations were used. The software intended for simulations is Ansoft Simplorer, which is a mixed‐technology simulator for electrical, electromechanical, power electronic systems and drive applications. For the verification of theoretical results the full‐scale laboratory prototype of the proposed converter was developed and tested.Findings – Thanks to increased switching frequency and current‐doubler rectifier (CDR) implemented in the proposed converter, the power dissipation...

High voltage Auxiliary Power Supply with the simplified power circuit topology for the DC trains

The paper proposes a simplified power circuit topology for the auxiliary power supplies (APS) with output powers up to 50 kW to be used in 3.0 kV DC commuter trains. Focus is on the implementation of 6.5 kV IGBTs to improve power density, system integrity as well as the reliability of the APS. For instance, a topology proposal, an analysis and a comparison with other types is presented. Some problems of converter control and protection as well as hardware design considerations are discussed. Efficiency estimation of the new topology and some recommendations of loss minimization are given.

Computer Models for Simulation and Control of a Traction Supply System

The paper discusses modelling and simulation of power circuits. Models were used to study energy exchange and develop a control system, in particular for vehicles with regenerative braking capability. SIMULINK models were used in control system design, including the selection of circuit components for feedbacks of switched mode converters. Models of the supply circuit were designed as independent blocks. These blocks can be used both, for AC induction motor drives and DC chopper drives. This structure can be used for the behavioural modelling of supply for switched-mode voltage-source traction converters.

The Handle of Substation Remote Terminal Unit Configuration

The Handle of Substation Remote Terminal Unit Configuration The remote control and supervision of electrical power transmission system is the balanced system between electricity generating and consuming, taking the responsibility for the stability of power supply consuming. The device to be responsible for above-mentioned tasks is a Remote Terminal Unit with faultless proper configuration.