Active Suction Circuit for Rail Traction Converter DC Link Loss Reduction

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Solution Overview

Problem

The existing passive suction circuits in rail vehicle traction converters are heavy, voluminous, and cost-intensive due to their reliance on passive components, which are inefficient and require frequent adjustments for different network frequencies.

Innovation Solution

An active suction circuit arrangement using a series connection of switching units, inductors, and capacitive energy storage, controlled by a device to dynamically adjust resonance frequency and compensate for pulsating energy components, reducing weight, volume, and energy losses.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a passive absorption circuit with heavy inductors and capacitors is used, then the pulsating energy components can be compensated, but the weight and volume of the traction converter increase significantly

Engineering Contradiction:

Improveenergy compensation efficiencyVSAvoidweight of absorption circuit

Core Design Contradiction:

Loss of energyVSWeight of moving object

Solution Approach 1:

The patent replaces the passive mechanical/electrical absorption circuit (with heavy inductors and capacitors) with an active control system using power semiconductor switches. The control device dynamically adjusts the switching states to compensate for pulsating energy components, eliminating the need for bulky passive components while maintaining energy compensation functionality.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The invention changes the operating parameters of the absorption circuit by using controllable power semiconductor switches that can dynamically adjust their switching frequency and duty cycle. This allows the circuit to adapt to different operating conditions and compensate for pulsating energy without requiring fixed, heavy passive components designed for worst-case scenarios.

Inventive Principle:

Principle #35Parameter changes

2Reliability

If passive components are used in the absorption circuit, then the circuit can operate, but the cost of the traction converter increases due to expensive inductors and capacitors

Engineering Contradiction:

Improvecircuit operation reliabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent substitutes expensive passive components (inductors and capacitors) with power semiconductor switches and a control device. This replacement reduces material costs while maintaining or improving reliability through active control that can detect and respond to circuit conditions in real-time.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The control device monitors the circuit conditions and automatically adjusts the switching states of the power semiconductors to maintain reliable operation. This self-regulating capability ensures circuit reliability without requiring expensive over-engineered passive components that would guarantee operation under all conditions.

Inventive Principle:

Principle #25Self-service

3Device complexity

If passive absorption circuit components are used, then the circuit structure is simple, but the volume occupied by the circuit increases

Engineering Contradiction:

Improvecircuit structure simplicityVSAvoidvolume of absorption circuit

Core Design Contradiction:

Device complexityVSVolume of moving object

Solution Approach 1:

The patent replaces volume-intensive passive components with power semiconductor switches that have much smaller physical footprints. The control device, which generates switching signals, occupies minimal space compared to the large inductors and capacitors in a passive absorption circuit, thereby reducing the overall volume significantly.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

4Loss of energy

If passive components are used in the absorption circuit, then the circuit can be implemented, but the ohmic losses in the inductors increase energy consumption

Engineering Contradiction:

Improveohmic lossesVSAvoidenergy consumption

Core Design Contradiction:

Loss of energyVSUse of energy by moving object

Solution Approach 1:

The patent replaces lossy passive inductors with power semiconductor switches that have much lower on-resistance. The active control mechanism directs current flow through optimized paths and minimizes resistive losses, thereby reducing overall energy consumption compared to passive absorption circuits where ohmic losses in inductors are significant.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 active suction circuit reduces weight and volume, enhances efficiency by minimizing losses, and eliminates the need for frequency adjustment devices, making it suitable for multi-system rail vehicles.

Implementation Method 1

each switching unit comprises two terminals, at least two controllable power semiconductor switches and at least one switching unit capacitance and is designed to provide at least two different voltages at the terminals depending on the switching positions of the power semiconductor switches

Methodology Applied

Scientific EffectElectrical switching: Conduction (electrical)

Implementation Method 2

the at least one inductance is connected in series with at least one switching unit

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Implementation Method 3

at least one capacitive energy store, wherein the at least one capacitive energy store is connected in series with the at least one switching arrangement

Methodology Applied

Scientific EffectCapacitance: Capacitance

Implementation Method 4

a control device, wherein the control device is designed to control at least the power semiconductor switches of the at least one switching unit

Methodology Applied

Scientific EffectSemiconductor switching: Conduction (electrical)

Data Source

PatentEP4492663A1Suction circuit arrangement for a traction converter of a rail vehicle

Publication Date: 2025.01.15 SIEMENS MOBILITY GMBH

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Figure 3A~3B

AI summary

A resonant circuit arrangement according to the invention for a traction converter of a rail vehicle, wherein the traction converter has at least one grid-side first converter, at least one load-side second converter, a DC link connecting the at least one first converter and the at least one second converter with a first and a second voltage potential, and at least one DC link capacitor arranged in the DC link, is characterized in that the resonant circuit arrangement arranged in the DC link and connected in parallel to the at least one DC link capacitor comprises at least one switching arrangement including at least one switching unit and at least one inductor, wherein each switching unit comprises two terminals, at least two controllable power semiconductor switches and at least one switching unit capacitor, and is configureddepending on the switching positions of the power semiconductor switches, providing at least two different voltages at the terminals, and wherein the at least one inductor is connected in series with at least one switching unit, comprising at least one capacitive energy storage device, wherein the at least one capacitive energy storage device is connected in series with the at least one switching arrangement, and a control device, wherein the control device is configured to control at least the power semiconductor switches of the at least one switching unit.