Junction Box Current Imbalance Detection for Parallel Switch Failure

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Solution Overview

Problem

Existing junction boxes with parallel-connected power switches fail to detect single switch failures effectively due to shared current distribution, leading to undetectable faults and potential system damage.

Innovation Solution

Implementing a split current sensing system with separate current sensors for each set of parallel-connected power switches, allowing for detection of current imbalances and identifying failed switches, thereby enabling timely corrective action.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If parallel-connected power switches share current distribution, then device complexity is reduced, but reliability deteriorates due to undetectable single switch failures

Engineering Contradiction:

Improvecurrent sensing system complexityVSAvoidswitch failure detection capability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The current sensing system is segmented into multiple independent sensing paths, with each current sensor dedicated to monitoring a specific subset of parallel-connected power switches. This segmentation enables independent detection of current imbalances in each group, allowing the system to identify which specific switches have failed while maintaining a relatively simple overall architecture.

Inventive Principle:

Principle #1Segmentation

2Reliability

If separate current sensors are used for each parallel switch, then reliability improves through failure detection, but device complexity increases

Engineering Contradiction:

Improveswitch failure detection capabilityVSAvoidcurrent sensing system complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

Each current sensor is assigned to monitor a specific local group of parallel-connected power switches, creating localized sensing zones. This local quality approach ensures that each sensor provides detailed information about its designated group, enabling precise failure identification without requiring every sensor to monitor every switch, thus balancing reliability with manageable complexity.

Inventive Principle:

Principle #3Local quality

3Device complexity

If a single current sensor monitors all parallel switches, then device complexity is minimized, but measurement precision deteriorates due to inability to detect single switch failures

Engineering Contradiction:

Improvenumber of current sensorsVSAvoidswitch failure detection accuracy

Core Design Contradiction:

Device complexityVSMeasurement precision

Solution Approach 1:

The system transitions from a single-dimension monitoring approach (one sensor for all switches) to a multi-dimensional monitoring structure where multiple sensors monitor different subsets of switches. This dimensional change in the sensing architecture enables the system to detect current imbalances in specific groups, providing precise failure identification while maintaining a reasonable number of sensors.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

Data Source

PatentUS20240072639A1Junction Box Having Parallel Switch Failure Detection

Publication Date: 2024.02.29 LEAR CORP

AI summary

A junction box comprises parallel-connected switches comprising at least a first switch and a second switch. A first current sensor senses current through the first switch. A second current sensor senses current through the second switch. A controller is in communication with the first and second current sensors. The controller modifies operation of the junction box in response to detecting at least one of the switches is failed. The controller detects that one of the first switch and the second switch is failed when the current through the first switch and the current through the second switch are unbalanced.