Modular Train Traction Power Layout for Flexible Formation Changes

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Solution Overview

Problem

Current traction power unit structures in urban trains are large and heavy, occupying significant space and weight, leading to poor power redundancy and inflexible train formations that cannot meet acceleration requirements or quickly adjust formation, resulting in inefficient energy consumption.

Innovation Solution

A traction power system for a variable formation train comprising two fixed traction power units and N variable traction power units, where N is a natural number, with each unit including specific components connected via disconnect switches to a high-voltage busbar, allowing flexible train formation adjustments and high power redundancy.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If traditional fixed traction power unit structure is used, then each transformer and converter has dedicated cooling unit ensuring reliable operation, but the high-voltage traction system occupies large indoor space and large train weight

Engineering Contradiction:
Improvecooling reliabilityVSAvoidtraction system weight
Core Design Contradiction:
ReliabilityVSWeight of stationary object

Solution Approach 1:

The patent combines multiple cooling units into a shared common cooling system that serves multiple transformers and converters. The cooling units include cooling pumps, heat exchangers, and cooling towers that are共用 among different traction power equipment, reducing total weight while maintaining adequate cooling capacity through centralized thermal management.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The cooling units are designed with universal applicability to serve multiple types of traction equipment (transformers, converters, auxiliary converters) within the same train set. The common cooling system can dynamically allocate cooling capacity to different equipment based on their thermal demands, making the cooling infrastructure multi-functional rather than dedicated to single equipment.

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

2Reliability

If traditional fixed traction power unit structure is used, then each component has dedicated cooling, but the system requires fixed train formations with poor flexibility

Engineering Contradiction:
Improvecooling provisionVSAvoidformation flexibility
Core Design Contradiction:
ReliabilityVSAdaptability or versatility

Solution Approach 1:

The train is divided into modular traction power units (TPUs) that can be independently configured. Each TPU contains complete traction equipment (transformers, converters, motors) that can operate autonomously or in combination with other TPUs. This segmentation enables flexible formation adjustments by adding or removing complete modular units without compromising the cooling infrastructure, as each module has access to the common cooling system.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The train formation is designed to be dynamically adjustable by reconfiguring the number and arrangement of modular TPUs. The common cooling system dynamically adapts to different formation configurations by redistributing cooling capacity among the active traction equipment, enabling the train to transition between different formation modes (e.g., 6-car, 8-car, 10-car formations) while maintaining reliable cooling provision.

Inventive Principle:
Principle #15Dynamics

3Power

If traditional traction power unit structure is used, then components are large in size, but the system achieves adequate power output

Engineering Contradiction:
Improvetraction power outputVSAvoidtraction system volume
Core Design Contradiction:
PowerVSVolume of stationary object

Solution Approach 1:

Multiple traction power functions are merged into integrated modular TPUs that combine transformers, converters, auxiliary converters, and traction motors in compact arrangements. The common cooling system is shared across all power equipment, eliminating redundant cooling infrastructure and reducing overall system volume while maintaining adequate power output through coordinated operation of multiple modules.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The modular TPU design incorporates multi-functional equipment that can serve multiple purposes. For example, the common cooling system serves transformers, converters, and auxiliary converters simultaneously. The modular architecture allows TPUs to be configured in different numbers and arrangements to meet various power requirements, achieving scalable power output without proportionally increasing system volume.

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

4Device complexity

If fixed train formation is used, then traction system structure is simple, but the system has poor power redundancy and cannot meet acceleration requirements

Engineering Contradiction:
Improvetraction system structureVSAvoidpower redundancy
Core Design Contradiction:
Device complexityVSReliability

Solution Approach 1:

The traction system is segmented into multiple independent TPUs, each capable of providing complete traction power functions. This segmentation creates inherent power redundancy because if one TPU fails, other TPUs can continue operating to maintain train propulsion. The modular structure adds complexity only at the module level, while the overall system architecture remains relatively simple through standardized interfaces and configurations.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The system achieves variable power redundancy by changing the operational status of individual TPUs based on system requirements. During normal operation, all TPUs contribute to total power output. When acceleration requirements increase or faults occur, the system dynamically adjusts the number of active TPUs, thereby changing the effective power redundancy parameter without requiring permanent structural complexity.

Inventive Principle:
Principle #35Parameter changes

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 system enables rapid transitions between different train formations, improves formation flexibility, optimizes power utilization, and meets starting acceleration requirements, while reducing manual intervention through disconnect switches for fault handling.

Implementation Method 1

an output end of the first traction converter is further connected to an input end of the first auxiliary converter, an output end of the first auxiliary converter is connected to the first storage battery, and the first auxiliary converter is configured to charge the first storage battery

Methodology Applied
Scientific EffectElectrical energy storage: Battery (electricity)

Data Source

PatentEP4681973A1Traction power system for variable formation train and variable formation train
Publication Date: 2026.01.21 CRRC CHANGCHUN RAILWAY VEHICLES CO LTD
  • EP4681973A1 patent drawingFigure 1
  • EP4681973A1 patent drawingFigure 2
  • EP4681973A1 patent drawingFigure 3

AI summary

The present application relates to the technical field of rail vehicles, and provides a traction power system for a variable formation train and a variable formation train. The traction power system comprises two fixed traction power units and N variable traction power units (2), the fixed traction power units are arranged on a leading car, and the variable traction power units (2) are arranged on intermediate cars. A train formation can be adjusted according to the requirements of different operational scenarios, rapidly achieving transitions between different formation forms of a train, greatly improving the flexibility of the train formation, and achieving the optimal train performance utilization. In addition, the fixed traction power units and the variable traction power units (2) exhibit high independence, the transitions between different formation forms are convenient, the train variable formation operation efficiency is improved; and the power redundancy is high, and the starting acceleration requirement of a user for a suburban train can be well met.