Rail Vehicle Drive System Short-Circuit Protection

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Solution Overview

Problem

The existing drive systems for rail vehicles with transformers and line-side converters face inefficiencies due to high leakage inductances, which limit current increase during faults and reduce protective effects, leading to increased energy consumption and potential damage from short-circuit currents.

Innovation Solution

A short-circuit protection device is integrated between the secondary side of the transformer and the line-side converter, utilizing semiconductors to limit short-circuit currents and reduce leakage inductance, thereby protecting the system from damage and optimizing efficiency by reducing short-circuit voltage and energy consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If the stray inductance of the transformer is reduced to improve efficiency, then copper losses are reduced and efficiency increases, but the protective effect against short-circuit currents is reduced

Engineering Contradiction:

Improvecopper lossesVSAvoidprotective effect against short-circuit currents

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

A short-circuit protection device is introduced as an intermediary component between the transformer and the grid-side converter. This device includes a controllable switch that can be activated during faults to limit short-circuit currents, thereby protecting the system while allowing the transformer to operate with reduced stray inductance for improved efficiency.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The short-circuit protection device is pre-configured and ready to activate before a fault occurs. The controllable switch is designed to respond rapidly to fault conditions, establishing protection in advance of potential damage to semiconductors and other sensitive components.

Inventive Principle:

Principle #10Preliminary action

2Object-generated harmful factors

If high short-circuit voltages are used in transformers to limit interference currents, then interference currents are limited, but energy efficiency decreases due to increased copper losses

Engineering Contradiction:

Improveinterference currentsVSAvoidcopper losses

Core Design Contradiction:

Object-generated harmful factorsVSLoss of energy

Solution Approach 1:

The short-circuit protection device acts as a mediator that provides interference current limitation without requiring high short-circuit voltages. The controllable switch in the protection device limits fault currents directly, allowing the transformer to operate with lower short-circuit voltage and reduced copper losses while still maintaining interference current control.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Use of energy by moving object

If the short-circuit voltage of the transformer is reduced to improve efficiency, then energy consumption decreases, but the ability to limit short-circuit currents is reduced

Engineering Contradiction:

Improveenergy consumptionVSAvoidshort-circuit currents

Core Design Contradiction:

Use of energy by moving objectVSObject-affected harmful factors

Solution Approach 1:

The short-circuit protection device serves as a dedicated intermediary for limiting short-circuit currents, decoupling this function from the transformer's short-circuit voltage. This allows the transformer to be optimized for energy efficiency with reduced short-circuit voltage while the protection device handles interference current limitation independently.

Inventive Principle:

Principle #24Intermediary (Mediator)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The short-circuit protection device effectively limits short-circuit currents and reduces leakage inductance, enhancing the overall efficiency of the rail vehicle's drive system, minimizing energy consumption, and preventing damage to semiconductors by controlling short-circuit voltages and currents.

Implementation Method 1

a short-circuit current through the semiconductors of the grid-side converter can be limited by means of the short-circuit protection device

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Implementation Method 2

a transformer and a grid-side power converter with semiconductors and an intermediate circuit

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentEP3575127B1Drive system for a rail vehicle with a secondary transformer-side short-circuit protection device

Publication Date: 2023.06.14 SIEMENS MOBILITY GMBH DE

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Figure 3~4
Figure 5~6

AI summary

The invention relates to a drive system (1) for a rail vehicle (2), wherein the drive system (1) comprises a transformer (3), a grid-side converter (4) with semiconductors (41) and an intermediate circuit, and a short-circuit protection device (5), wherein the short-circuit protection device (5) is arranged between a secondary side (31) of the transformer (3) and the grid-side converter (4), and wherein a short-circuit current through the semiconductors (41) of the grid-side converter (4) can be limited by means of the short-circuit protection device (5). The invention further relates to a rail vehicle (2) with such a drive system (1), wherein the rail vehicle (2) is designed for operation on an overhead line (7) with alternating current.The invention further relates to a method for protecting such a drive system (1), wherein in the event of a fault a short-circuit current through the semiconductors (41) of the grid-side converter (4) is limited by means of the short-circuit protection device (5).