Railway Traction Applications Research Articles

Comprehensive Compact Models for the Circuit Simulation of Multichip Power Modules

This paper proposes the model development of a packaged semiconductor power module, for use in a circuit simulation environment. Focusing on railway traction applications, it considers a state-of-the-art 6.5 kV insulated gate bipolar transistor (IGBT) module, taking into account the antiparallel connection of IGBTs and free-wheeling diodes, and including all main electrothermal and electromagnetic effects associated with the multichip structure. The description of semiconductor physics is coupled with self-heating effects; electromagnetic phenomena associated with the packaging, layout, and interconnections are also taken into account. To optimize the compromise between accuracy and computational effort, the device models are based on a mixed physical and behavioral description, and are scalable to be representative of a desired number of parallel devices and to allow for the introduction of parasitic elements, as required. Electromagnetic effects are modeled by means of equivalent lumped elements, extracted by numerical simulation of an accurate 3-D structural assembly model. The description of transient thermal phenomena relies on a finite-difference approach that considers the use of both essentially 1-D lumped equivalent models and fully 3-D distributed description. The model is validated statically and dynamically, against both data-sheet information and measurements; a selection of simulation examples demonstrates its usefulness and versatility. Although developed for a specific application scenario, the proposed approach is of general validity.

A Multi-Purpose Balanced Transformer for Railway Traction Applications

A multi-purpose balanced (MPB) transformer is proposed in this paper for electric railway applications. The MPB transformer is developed from impedance-matching (IM) transformers widely used in China's railway systems. The proposed MPB transformer has three main functions: (1) it provides a symmetrical two-phase voltage of 27.5 kV for railway overhead lines to power electric trains; (2) it supplies a three-phase balanced voltage of 10.5 kV for railway substations; and (3) it can accommodate a three-phase harmonic filter with improved power factor and reduced manufacturing cost. In this paper, the operating principles of the MPB transformer are elaborated, the design of the harmonic filters is discussed, and the results of computer simulations are provided. A 16-MVA MPB transformer was designed and commissioned, and real-time field measurements are provided.

Performance and reliability testing of modern IGBT devices under typical operating conditions of aeronautic applications

As for railway traction applications, aeronautical power electronics implies high power density handling. Moreover typical aeronautical applications impose a harsh thermal environment. SiC technology has recently emerged for high power and high temperature application, but is not yet mature enough. Consequently it is still important to push the silicon devices temperature limits in order to increase the amount of switched power. Device ageing is accelerated and there exists the risk of catastrophic failure by thermal runaway. In order to design correctly high temperature power systems, knowing the IGBT characteristics at extended temperature ranges becomes essential. This paper describes an experimental setup and test procedure conceived to experiment with different available IGBT technologies at temperatures beyond the limits rated by manufacturers (−55 °C, +175 °C). The aim is to characterize the devices for a better understanding and optimized safe application. This will ease prototyping for future development of IGBT modules in aircraft.

Robustness test and failure analysis of IGBT modules during turn-off

Considering the typical operational conditions of railway traction applications, this paper proposes an insightful study of the failure mechanism of IGBT modules when exposed to various limit load conditions during turn-off. First, the results of extensive experimental analysis are presented. These are based on a dedicated test-circuit and point out a repetitive failure mechanism. This is subsequently investigated by means of simulations based on a compact model which includes all major and secondary electro-thermal effects (i.e. latch-up). The results enable an interpretation of the observations and point out how the limits of transient safe operation can be significantly reduced by parasitic effects.

Virtual reliability assessment of integrated power switches based on multi-domain simulation approach

To develop reliable integrated power electronics, it is paramount to consider the coupling between electrical, thermal and mechanical effects. Though essential for final validation, experimental analysis is time-consuming, especially when trying out new designs. Simulative approaches at multi-domain physical analysis need to be improved. In this work, a platform is proposed, in which all physics are treated with dedicated simulation programmes, co-ordinated by a custom-developed core section. A case study, based on a novel integrated power switch developed for railway traction applications, demonstrates the validity of the envisaged solution for virtual reliability assessment.

Weighted Control of Traction Drives With Parallel-Connected AC Machines

AC machines supplied in parallel by a common voltage source inverter are sometimes used in industrial drives and railway traction applications. This reduction of power and control electronics leads to a reduction of cost, weight, and dimensions that is very useful for on-board systems. But this common supply imposes common voltages to all machines and the possibilities of independent behavior are reduced. In this paper, a graphical modeling is suggested to model such parallel drives for a railway application. A weighted control is then systematically deduced from this modeling and different possibilities of control are highlighted. Experimental results are provided to compare two of the deduced controls

Long term reliability testing of HV-IGBT modules in worst case traction operation

Abstract High reliability level is required for IGBT modules used in power converters in railway traction application which however are subject to high stress because of the typical cycling operation which causes thermomechanical fatigue. The paper reports about Ansaldo Trasporti activity in IGBT's reliability testing. Facility simulating worst case traction operation is described and the result after operation is presented: due to such stressing action, a solder delamination at the baseplate seems to be the first failure mechanism to be excited.

Advanced IGBT modules for railway traction applications: Reliability testing

IGBT modules for railway traction applications have to be more intensively tested then those for industrial application. The paper describes the state of the art of already existing reliability test as well as a proposal for accelerated power cycling and temperature cycling tests. These tests are a result of the Brite EuRam research project RAPSDRA (reliability of advanced power semiconductor devices for railway traction application).