Auxiliary Converter High Power Rectifying Stage

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Solution Overview

Problem

Current railway auxiliary supply architectures face challenges in providing sufficient power to start the main compressor for lifting the pantograph when the train is not connected to the catenary, as existing reversible battery chargers are not adapted to handle the high starting current demands of the compressor.

Innovation Solution

An auxiliary converter with a high power rectifying and inverting stage, comprising a single phase rectifier, buffer capacitors, and a three-phase inverter, connected to a transformer stage, which allows the reversible battery charger to supply power to the main compressor during battery operating mode, enabling it to start the compressor without oversizing the battery charger.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If a traditional reversible battery charger topology is used, then the battery charger can supply power to auxiliary loads, but it cannot deliver sufficient starting current to the main compressor

Engineering Contradiction:

Improvestarting current delivery capabilityVSAvoidbattery charger topology complexity

Core Design Contradiction:

PowerVSDevice complexity

Solution Approach 1:

The power delivery function is segmented between the existing reversible battery charger (for steady-state power) and a new high-power rectifying and inverting stage (for high starting current). This segmentation allows each component to be optimized for its specific function without requiring the battery charger to be oversized.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The high-power rectifying and inverting stage acts as an intermediary between the battery charger and the main compressor. It receives power from the battery charger and delivers the high starting current required by the compressor, protecting the battery charger from direct exposure to high inrush currents.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If an additional dedicated converter is added to power the main compressor from the battery, then the compressor can start in battery operating mode, but the device complexity and cost increase

Engineering Contradiction:

Improvebackup power supply reliabilityVSAvoidconverter quantity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The high-power rectifying and inverting stage is designed to handle multiple functions: it can power the main compressor during starting, support emergency ventilation fans, and provide backup power to other auxiliary loads. This multi-functionality eliminates the need for separate dedicated converters for each load type.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The patent merges the functions of the reversible battery charger with the high-power rectifying and inverting stage to create an integrated power delivery system. This combination allows the system to leverage the existing battery charger infrastructure while adding only the necessary high-power stage, rather than installing multiple separate converters.

Inventive Principle:

Principle #5Merging (Combining)

3Power

If the battery charger is oversized to handle compressor starting current, then the compressor can start without additional equipment, but the cost and size of the battery charger increase

Engineering Contradiction:

Improvestarting current capacityVSAvoidbattery charger size

Core Design Contradiction:

PowerVSQuantity of substance

Solution Approach 1:

Inventive Principle:

Principle #1Segmentation

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

This solution enables the auxiliary converter to deliver the necessary high starting current to the main compressor, reducing the need for additional converters and minimizing costs by using the existing battery charger effectively, allowing for efficient operation even when the pantograph is down.

Implementation Method 1

a single phase rectifier, a set of buffer capacitors and a three phase inverter

Methodology Applied

Scientific EffectRectification: Diode

Implementation Method 2

a single phase rectifier, a set of buffer capacitors and a three phase inverter

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 3

a single phase rectifier, a set of buffer capacitors and a three phase inverter

Methodology Applied

Scientific EffectInversion:

Implementation Method 4

a transformer stage connected to the main inverter output and adapted to convert, in a catenary operating mode, the AC voltage from the main inverter stage

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentEP3308996B1An auxiliary converter for a railway vehicle

Publication Date: 2021.12.01 ALSTOM HOLDINGS SA

Figure 1
Figure 2

AI summary

An auxiliary converter for providing power to auxiliary loads of an auxiliary electrical network of a railway vehicle, the auxiliary loads including a main air compressor, the auxiliary converter comprising: a main inverter stage with a main inverter input and a main inverter output; a transformer stage connected to the main inverter output and adapted to convert, in a catenary operating mode, the AC voltage from the main inverter stage; and a reversible battery charger stage connected to said charging output and adapted to charge, in said catenary operating mode, an electrical battery of said railway vehicle, wherein the reversible battery charger stage is adapted to, in a battery operating mode, deliver a supply voltage from the battery to said transformer stage for powering auxiliary loads, characterised by a high power rectifying and inverting stage connected to said supply output and for providing power to said auxiliary loads of said auxiliary electrical network.