Rail Vehicle Traction Battery Startup Without a Separate Low-Voltage Battery

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Solution Overview

Problem

Existing rail vehicles require separate, heavy, and complex low-voltage batteries for vehicle control systems, which occupy significant space and increase weight, conflicting with weight and load limits, especially when combined with traction batteries.

Innovation Solution

A method utilizing a traction battery voltage converter to supply the vehicle control system and electrical system directly, eliminating the need for a separate low-voltage battery by integrating the power converter and auxiliary converter into a common housing, allowing power from the traction battery to be used for startup and operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate low-voltage battery is installed to power the vehicle control system and electrical system, then the vehicle can operate reliably, but the vehicle weight increases significantly and installation space is required

Engineering Contradiction:
Improvevehicle control system power supplyVSAvoidvehicle weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent merges the functions of the low-voltage battery and power converter into a single integrated power supply system. The power converter is electrically connected to the high-voltage traction battery and outputs both high-voltage and low-voltage currents, eliminating the need for a separate low-voltage battery while maintaining reliable power supply for the vehicle control system and electrical system.

Inventive Principle:
Principle #5Merging (Combining)

2Reliability

If a separate low-voltage battery is installed to power the vehicle control system, then the vehicle can operate reliably, but the installation space and device complexity increase

Engineering Contradiction:
Improvevehicle control system power supplyVSAvoidbattery installation complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent combines the power converter and what would traditionally be a separate low-voltage battery system into a single integrated unit. This merging reduces device complexity by eliminating the need for separate battery compartments, ventilation systems, and explosion-proof enclosures, while the power converter provides both high-voltage and low-voltage power outputs.

Inventive Principle:
Principle #5Merging (Combining)

3Reliability

If lead-acid or nickel-cadmium batteries are used for low-voltage power supply, then the vehicle control system can be powered, but the batteries require dedicated explosion-proof compartments with independent ventilation

Engineering Contradiction:
Improvelow-voltage power supplyVSAvoidcompartment ventilation system
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical/chemical battery system (lead-acid or nickel-cadmium) with an electrical power conversion system. The power converter uses electrical energy from the high-voltage traction battery to generate low-voltage current, eliminating the need for chemical batteries and their associated explosion-proof compartments and ventilation systems.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

4Reliability

If additional batteries are installed in vehicles with traction batteries, then the vehicle control system can be powered, but the maximum permissible wheel load or vehicle weight is exceeded

Engineering Contradiction:
Improvevehicle control system power supplyVSAvoidvehicle weight
Core Design Contradiction:
ReliabilityVSWeight of moving object

Solution Approach 1:

The patent makes the power converter multi-functional by enabling it to provide both high-voltage power for the traction system and low-voltage power for the vehicle control system and electrical system. This universal power supply function eliminates the need for additional batteries, keeping the vehicle within permissible weight and load limits.

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enables a simple, weight-saving design by eliminating the need for additional batteries, providing reliable power to the vehicle systems, and optimizing space usage within the rail vehicle.

Implementation Method 1

a traction battery voltage converter for starting up the vehicle's voltage converter with electrical energy from the traction battery

Methodology Applied
Scientific EffectElectrical energy conversion:

Data Source

PatentEP4520573B1Rail vehicle comprising a traction battery and a converter and method for switching on a rail vehicle
Publication Date: 2026.03.18 STADLER RAIL
  • EP4520573B1 patent drawingFigure 1
  • EP4520573B1 patent drawingFigure 2
  • EP4520573B1 patent drawingFigure 3

AI summary

The invention relates to a rail vehicle (12) comprising a traction battery (8) and a power converter (4). The power converter (4) can be supplied with electrical current by the traction battery (8). The power converter (4) is connected to a DC electrical system (7) via a power converter voltage converter (6). The invention also relates to a method for switching on a rail vehicle (12). In this method, the vehicle voltage converter (2) is first supplied with energy from the traction battery (8) via the DC electrical system (7) before the power converter (4) is activated.