Railway Vehicle Noise Current Path Control

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Solution Overview

Problem

Existing railway vehicle designs fail to effectively prevent noise currents from diffusing and flowing out to structures other than the vehicle body, leading to potential malfunctions and inductive disturbances due to parasitic capacitance and mutual induction with the vehicle body.

Innovation Solution

A railway vehicle configuration that utilizes the vehicle body as a noise current main path by incorporating a ground conductor connecting the main conversion device to the vehicle body and a return conductor connecting the motor frame to the vehicle body, with a wire support structure keeping the three-phase wire close to the vehicle body, thereby reducing noise current diffusion through mutual induction.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If a wiring duct is used to house the three-phase wire and connect the motor to the main conversion device, then the noise current path is controlled, but parasitic capacitance between the wire and duct causes noise current to diffuse to the vehicle body

Engineering Contradiction:
Improvenoise current diffusionVSAvoidwiring structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent introduces a noise current countermeasure wire as an intermediary element. This wire is disposed between the three-phase wire and the vehicle body, serving as a dedicated path to guide noise current back to the main conversion device. The intermediary wire actively manages the parasitic capacitance effect by providing a controlled return path, preventing noise current from diffusing to the vehicle body while maintaining the simplicity of the wiring duct structure.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If the vehicle body is completely isolated from the noise current path, then noise current diffusion is prevented, but parasitic capacitance and mutual induction with the vehicle body cannot be eliminated

Engineering Contradiction:
Improvenoise current diffusionVSAvoidnoise prevention reliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The patent converts the harmful parasitic capacitance effect into a beneficial feature by utilizing it to guide noise current along a predetermined path. Instead of trying to eliminate the capacitance between the three-phase wire and vehicle body, the invention uses the noise current countermeasure wire to harness this capacitance effect, directing the noise current through the wire back to the main conversion device. This transforms the previously harmful diffusion path into a controlled and manageable return path.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

3Object-affected harmful factors

If a separate return path is configured using wire or conduit, then noise current path control is improved, but a new noise current path with lower inductance is formed via parasitic capacitance, complicating the problem

Engineering Contradiction:
Improvenoise current path controlVSAvoidwiring structure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent merges the noise current countermeasure wire with the existing wiring duct structure. Instead of creating a completely separate return path that would add complexity, the countermeasure wire is integrated into the duct system, utilizing the same spatial infrastructure. This merging approach provides effective noise current path control while avoiding the need for additional complex wiring arrangements, as the countermeasure wire shares the duct space with the three-phase wire.

Inventive Principle:
Principle #5Merging (Combining)

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 configuration significantly reduces noise current diffusion, minimizing malfunctions and inductive disturbances, and provides a stable noise return current path, reducing radiation noise and preventing malfunctions in on-track and on-vehicle devices.

Implementation Method 1

a ground conductor that electrically connects the main conversion device and the vehicle body; and a return conductor that electrically connects a frame of the motor and the vehicle body

Methodology Applied
Scientific EffectElectrical conduction: Conduction (electrical)

Implementation Method 2

reduces noise current diffusion through mutual induction

Methodology Applied
Scientific EffectMutual induction: Electromagnetic Induction

Implementation Method 3

a parasitic capacitance between the three-phase wire and the wiring duct and a parasitic capacitance between the wiring duct and the vehicle body

Methodology Applied
Scientific EffectParasitic capacitance: Parasitic Capacitance

Data Source

PatentEP3785977A1Railway vehicle
Publication Date: 2021.03.03 HITACHI LTD
  • EP3785977A1 patent drawingFigure 1A~1B
  • EP3785977A1 patent drawingFigure 2A~2B
  • EP3785977A1 patent drawingFigure 3A~3B

AI summary

An object of the invention is to provide a railway vehicle, which positively utilizes a vehicle body as a noise current main path starting from a motor and prevents a noise current from diffusing and flowing out to structures other than the vehicle body, rails, or the like. The railway vehicle includes: a motor that is disposed on a bogie and is configured to rotationally drive a wheel; a main conversion device configured to convert a power supplied from an overhead wire into a three-phase alternating current power for driving the motor; a three-phase wire that connects the motor and the main conversion device and is configured to transmit the three-phase alternating current power; a vehicle body, which is a conductor, that continuously covers at least a space between the motor and the main conversion device; and a wire support structure that supports the three-phase wire such that the three-phase wire is close to the vehicle body side. The railway vehicle further includes: a ground conductor that electrically connects the main conversion device and the vehicle body; and a return conductor that electrically connects a frame of the motor and the vehicle body in a region where flexibility of the three-phase wire is required, and the return conductor is disposed so as to be close to and along the three-phase wire.