Failure Tolerant Capacitor Device with Segmented Detection

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Solution Overview

Problem

Multi-layer ceramic capacitors used in parallel configurations are prone to cracking and failure, leading to electrical shorts, which can disable entire electronic assemblies, especially in high-temperature applications, due to limitations in reliability and detection of initial cracks.

Innovation Solution

A failure-tolerant capacitor device with detection and disconnection mechanisms for each capacitor element, using transistors to monitor voltage and current thresholds, automatically disconnecting faulty capacitors to maintain system operation and provide monitoring signals for maintenance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Quantity of substance

If a large number of ceramic capacitors are connected in parallel to increase capacitance, then the capacitance value increases, but the reliability decreases due to higher statistical probability of cracks and failures

Engineering Contradiction:
ImprovecapacitanceVSAvoidreliability
Core Design Contradiction:
Quantity of substanceVSReliability

Solution Approach 1:

The capacitor bank is segmented into multiple independent capacitor elements, each with its own detection and connection elements. This segmentation allows individual capacitors to be isolated upon failure while maintaining operation of the remaining capacitors, thus preserving system reliability while enabling high total capacitance through parallel connection of multiple segments.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

The invention changes the operational state of individual capacitors dynamically by introducing detection elements that monitor voltage and current parameters. When a capacitor's voltage drops below a threshold or current exceeds a threshold (indicating failure), the connection element changes the capacitor's state from active to disconnected, maintaining overall system reliability.

Inventive Principle:
Principle #35Parameter changes

2Temperature

If ceramic capacitors are used in high-temperature applications, then the temperature tolerance increases, but the reliability decreases due to easier crack development during manufacturing and assembly

Engineering Contradiction:
Improvetemperature toleranceVSAvoidreliability
Core Design Contradiction:
TemperatureVSReliability

Solution Approach 1:

The detection elements are pre-configured to monitor capacitor health parameters before failures can propagate. By continuously detecting voltage and current thresholds, the system takes preliminary action to identify cracks or degradation early, allowing disconnection of affected capacitors before they cause complete system failure, thus maintaining reliability in high-temperature environments.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The invention implements feedback mechanisms where detection elements continuously monitor capacitor performance and provide real-time information about capacitor health. This feedback loop enables the connection elements to respond dynamically by disconnecting faulty capacitors, maintaining system reliability even when capacitors are subjected to high temperatures that accelerate degradation.

Inventive Principle:
Principle #23Feedback

3Quantity of substance

If parallel capacitor configurations are used, then the capacitance increases, but the ease of operation decreases due to inability to disconnect individual failed capacitors

Engineering Contradiction:
ImprovecapacitanceVSAvoidease of operation
Core Design Contradiction:
Quantity of substanceVSEase of operation

Solution Approach 1:

The capacitor bank implements self-service functionality through automated detection and disconnection mechanisms. Each capacitor element has its own detection element that autonomously monitors its own health status and triggers the connection element to disconnect it when failure is detected, eliminating the need for external manual intervention and maintaining ease of operation while enabling high capacitance.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The connection elements act as intermediaries between the capacitor elements and the rest of the circuit. These intermediaries can selectively connect or disconnect individual capacitors based on their operational status, providing ease of operation by automatically managing the capacitor bank's composition while maintaining the desired high capacitance through parallel configuration.

Inventive Principle:
Principle #24Intermediary (Mediator)

4Reliability

If detection and disconnection mechanisms are added to each capacitor element, then the reliability increases, but the device complexity increases

Engineering Contradiction:
ImprovereliabilityVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The detection and disconnection functions are segmented and distributed to each capacitor element individually rather than using a centralized complex system. Each capacitor element has its own simple detection element and connection element, which reduces overall system complexity while maintaining high reliability through distributed monitoring and control.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each capacitor element performs self-detection and self-disconnection operations through its own integrated detection and connection elements. This self-service approach eliminates the need for complex external monitoring and control systems, reducing device complexity while achieving high reliability through autonomous failure management at each capacitor level.

Inventive Principle:
Principle #25Self-service

Data Source

PatentEP3408678B1Failure tolerant capacitor device
Publication Date: 2019.10.16 ABB (SCHWEIZ) AG
  • EP3408678B1 patent drawingFigure 1~2
  • EP3408678B1 patent drawingFigure 3~4
  • EP3408678B1 patent drawingFigure 5~6

AI summary

A failure tolerant capacitor device (12) comprises a plurality of capacitor elements (18) connected in parallel; and, for each capacitor element (18), a detection element (22) and a connection element (24); wherein the detection element (22) is adapted for detecting a capacitor voltage across the capacitor element (18) falling below a predefined voltage threshold and/or for detecting a capacitor current through the capacitor element (18) raising above a predefined current threshold and for turning off the connection element (24), when the capacitor voltage is below the predefined voltage threshold and/or the capacitor current is above the predefined current threshold; and wherein the connection element (24) is adapted for disconnecting the capacitor element (18) from other ones of the plurality of parallel connected capacitor elements (18), when turned off. The connection transistor (38) is connected in series with the capacitor element (18), such that a collector of the connection transistor (38) is connected with the capacitor element (18). A base of the detection transistor (36) is connected to the collector of the connection transistor (38) and a base of the connection transistor (38) is connected to a collector of the detection transistor (36).