Capacitor Module Safety Device for High-Power Traction

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Solution Overview

Problem

High-capacity capacitor modules used in applications like electric traction face reliability issues due to potential unsafe operating states such as excessive voltage, current, temperature, and pressure, which can lead to damage, fire, or injury if not monitored and managed effectively.

Innovation Solution

A safety device connected to the capacitor module continuously monitors operating states and switches to a safety mode by limiting current, discharging capacitors, and employing sensors to detect anomalies like temperature, pressure, and electrolyte leaks, with features like current limiting, strain gauges, and safety valves to prevent damage and ensure safe operation.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Power

If capacitor modules are used for short-term provision of high power, then power capability is improved, but reliability deteriorates due to potential unsafe operating states

Engineering Contradiction:
Improvepower capabilityVSAvoidreliability
Core Design Contradiction:
PowerVSReliability

Solution Approach 1:

The safety device performs preliminary monitoring of operating parameters (temperature, pressure, voltage, current) and takes preventive action by switching to safety mode before unsafe conditions develop. This allows the capacitor module to operate at high power while maintaining reliability through advance detection and response to potential failures.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The safety device continuously monitors operating parameters and provides feedback control by comparing measured values against threshold values. When parameters exceed safe limits, the system automatically transitions to safety mode, creating a closed-loop control system that maintains reliability while enabling high power operation.

Inventive Principle:
Principle #23Feedback

2Power

If multiple capacitors are connected together to meet performance and voltage requirements, then power capability is improved, but device complexity increases

Engineering Contradiction:
Improvepower capabilityVSAvoiddevice complexity
Core Design Contradiction:
PowerVSDevice complexity

Solution Approach 1:

The safety device serves multiple functions simultaneously: it monitors temperature, pressure, voltage, and current; compares all parameters against threshold values; controls the transition to safety mode; and manages the discharge process. This multi-functional approach reduces overall system complexity despite the presence of multiple capacitors.

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

Solution Approach 2:

The patent combines multiple monitoring and control functions into a single integrated safety device that manages the entire capacitor module system. By merging temperature sensing, pressure sensing, voltage monitoring, current monitoring, and control logic into one device, the system achieves high power capability through multiple capacitors without proportionally increasing complexity.

Inventive Principle:
Principle #5Merging (Combining)

3Object-affected harmful factors

If the capacitor module is closed in a gas-tight manner, then protection against external contaminants is improved, but reliability deteriorates due to internal pressure buildup and electrolyte boiling

Engineering Contradiction:
Improveprotection against contaminantsVSAvoidreliability
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The safety device acts as an intermediary monitoring system that detects internal pressure and temperature changes caused by electrolyte heating. It mediates between the gas-tight sealing (which prevents contamination) and the potential for internal pressure buildup by providing early warning and triggering safety mode before dangerous pressure levels develop.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The safety device performs preliminary monitoring of temperature and pressure inside the gas-tight capacitor module, detecting conditions that precede electrolyte boiling and explosive failure. By taking preliminary action to switch to safety mode when threshold values are approached, the system maintains the benefits of gas-tight sealing while preventing catastrophic failures.

Inventive Principle:
Principle #10Preliminary action

4Reliability

If the safety device continuously monitors all operating parameters, then reliability is improved, but device complexity increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The safety device is designed as a multi-functional monitoring system that simultaneously tracks temperature, pressure, voltage, and current using integrated sensors and control logic. This universal monitoring approach improves reliability through comprehensive parameter detection while managing complexity by consolidating multiple monitoring functions into a single device rather than separate systems for each parameter.

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

The solution effectively recognizes and mitigates unsafe operating states, preventing damage and potential hazards by timely switching to a safety mode, reducing the risk of capacitor module failure and ensuring safe operation, thereby protecting the system and personnel.

Implementation Method 1

the safety device continuously monitors the temperature inside the capacitor module and initiates the safety operating mode if a specified maximum temperature is exceeded

Methodology Applied
Scientific EffectTemperature sensing:

Implementation Method 2

the safety device can monitor the pressure inside the capacitor module and trigger the safety operating mode if a predetermined maximum pressure is exceeded

Methodology Applied
Scientific EffectPressure sensing:

Implementation Method 3

the safety device has a strain gauge measuring the spatial extent or size of the capacitor(s); the safety operating mode is started when a predetermined maximum elongation measured value is exceeded

Methodology Applied
Scientific EffectStrain measurement:

Data Source

PatentEP1872454B1Arrangement comprising a capacitor module, and method for the operation thereof
Publication Date: 2012.12.12 SIEMENS AG
  • EP1872454B1 patent drawingFigure 1
  • EP1872454B1 patent drawingFigure 2

AI summary

The invention relates to an arrangement (10) comprising a capacitor module (20) with at least one capacitor (30). In order for such an arrangement to be operated in a particularly safe manner, the same is provided with a safety device (50) which is connected to the at least one capacitor, monitors the mode of operation of the capacitor (30) or the mode of operation of the capacitor module (20), and switches into a safe mode of operation in case a mode of operation is identified as unsafe.