Redundant Capacitor Discharge Circuit for Switch Failure Control

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Solution Overview

Problem

Conventional capacitor discharge circuits fail to control discharge when the discharge-controlling switch element experiences open or short-circuit failures, leading to uncontrolled discharge and potential overheating of the discharge resistor.

Innovation Solution

A dualized discharge circuit configuration with two parallel circuits, each comprising a discharge resistor, a discharge-controlling switch element, and a breaking switch element, where the control unit switches between them to maintain control even if one set fails, using a switching relay to alternate between the first and second discharge circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a single discharge-controlling switch element is used to control capacitor discharge, then the circuit structure is simple, but the reliability deteriorates because discharge control fails when the switch element experiences open or short-circuit failures

Engineering Contradiction:
Improvedischarge control reliabilityVSAvoiddischarge circuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The discharge circuit is segmented into two independent discharge circuits, each with its own discharge resistor and discharge-controlling switch element. This segmentation allows the system to maintain discharge control capability even when one switch element fails, as the other can still function independently to control capacitor discharge.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Each discharge circuit is equipped with a breaking switch element that can locally isolate the failed discharge circuit from the capacitor. This local quality enhancement allows the system to maintain overall functionality by isolating the defective segment while preserving the operational discharge circuit.

Inventive Principle:
Principle #3Local quality

2Reliability

If the discharge-controlling switch element is subjected to short-circuit failure, then the discharge continues uncontrollably, but adding protection mechanisms increases circuit complexity

Engineering Contradiction:
Improvedischarge control reliabilityVSAvoidprotection mechanism complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

A breaking switch element is added to each discharge circuit that can locally isolate the failed discharge circuit from the capacitor. This local isolation capability prevents uncontrolled discharge continuation by allowing the system to disconnect the defective discharge circuit while maintaining the other operational circuit.

Inventive Principle:
Principle #3Local quality

Solution Approach 2:

The control unit monitors the status of discharge-controlling switch elements and automatically switches between the first and second discharge circuits based on detected failures. This feedback mechanism enables automatic adaptation to failures without requiring complex external protection circuits.

Inventive Principle:
Principle #23Feedback

3Reliability

If a dualized discharge circuit configuration is implemented with two parallel circuits, then the reliability improves by maintaining control even if one set fails, but the device complexity increases

Engineering Contradiction:
Improvedischarge control reliabilityVSAvoiddischarge circuit structure
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The discharge circuit is segmented into two independent discharge circuits, each with its own discharge resistor and discharge-controlling switch element. This segmentation allows the system to maintain discharge control capability even when one switch element fails, as the other can still function independently to control capacitor discharge.

Inventive Principle:
Principle #1Segmentation

Solution Approach 2:

Both the first and second discharge circuits are designed with identical functionality, allowing either circuit to serve as the active discharge path. The control unit can universally switch between them based on failure detection, making each circuit a potential backup for the other and enhancing overall system reliability.

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

Ensures controlled discharge of the capacitor even if the first discharge-controlling switch element fails, preventing overheating by dispersing heat across both discharge resistors in case of simultaneous failures, thus protecting the circuit components.

Implementation Method 1

electric charges accumulated in the capacitor are discharged through the discharge resistor

Methodology Applied
Scientific EffectJoule heating: Joule Heating

Data Source

PatentEP3503394B1Discharge circuit for capacitor
Publication Date: 2020.08.26 MITSUBISHI ELECTRIC CORP
  • EP3503394B1 patent drawingFigure 1
  • EP3503394B1 patent drawingFigure 2

AI summary

Provided is a discharge circuit for a capacitor, capable of performing discharge control even if a discharge-controlling switch element for controlling discharge of the capacitor is subjected to a failure. The discharge circuit is a discharge circuit for a capacitor provided between a charging circuit and a ground, the discharge circuit including: a control unit 1 for performing control of charge and discharge on the capacitor 3; a first discharge circuit having a first discharge resistor 5, a first discharge-controlling switch element 6, and a first breaking switch element 7 which are connected in series, the first discharge circuit being connected in parallel to the capacitor 3; and a second discharge circuit having a second discharge resistor 8, a second discharge-controlling switch element 9, and a second breaking switch element 10 which are connected in series, the second discharge circuit being connected in parallel to the capacitor 3, wherein the first discharge circuit is used in a normal state, and discharge of the capacitor 3 is controlled through opening and closing of the first discharge-controlling switch element 6 in a state where the first breaking switch element 7 is ON.