Diode-Based Open Wire Detection in Battery Management

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Solution Overview

Problem

Current battery management systems lack effective open wire detection, which is critical for ensuring safety in applications like electric vehicles, where an open circuit condition can lead to dire consequences.

Innovation Solution

A battery management system with a diode circuit coupled between terminals of a battery management unit, utilizing analog to digital converters and logic blocks to detect open circuits by monitoring voltages across diodes, generating error indications when thresholds are exceeded, and communicating these errors to a main controller.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If open wire detection is implemented in battery management systems, then safety is improved, but device complexity increases

Engineering Contradiction:
ImprovesafetyVSAvoiddevice complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The open wire detection function is merged with the existing battery management system by integrating diode circuits into the terminal connection structure. The detection circuit shares the same physical infrastructure (terminals, conductive paths) as the battery management functions, allowing safety monitoring to be combined with existing system components rather than adding completely separate detection hardware.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The diode circuit serves multiple functions: it provides protection against reverse polarity connection and simultaneously enables open wire detection through voltage monitoring. This multi-functionality allows the system to achieve enhanced safety capabilities without proportionally increasing device complexity, as the same hardware infrastructure supports both protection and detection roles.

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

2Measurement precision

If voltage monitoring across diodes is used to detect open circuits, then detection precision is improved, but device complexity increases

Engineering Contradiction:
Improvedetection precisionVSAvoiddevice complexity
Core Design Contradiction:
Measurement precisionVSDevice complexity

Solution Approach 1:

The diode circuit acts as an intermediary element that translates the open wire condition into a measurable voltage signal. Instead of directly detecting the open circuit condition, the system uses the diode voltage as an intermediate indicator that can be easily monitored by standard ADC resources already present in the battery management system.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The detection system utilizes the existing ADC (analog-to-digital converter) resources within the battery management system to monitor diode voltages. The system serves itself by repurposing existing measurement infrastructure for the additional function of open wire detection, avoiding the need for dedicated detection hardware and thereby limiting the increase in device complexity.

Inventive Principle:
Principle #25Self-service

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 system effectively detects open wire conditions, preventing potential safety hazards by accurately identifying and communicating open circuit occurrences, thus enhancing safety in battery management applications.

Implementation Method 1

A diode circuit is coupled between terminals of a battery management unit. Monitor circuitry of the battery management unit is configured to monitor a voltage across the diode circuit.

Methodology Applied
Scientific EffectDiode voltage monitoring: Diode

Data Source

PatentEP3629040B1Open wire detection system and method therefor
Publication Date: 2023.03.29 NXP BV
  • EP3629040B1 patent drawingFigure 1
  • EP3629040B1 patent drawingFigure 2
  • EP3629040B1 patent drawingFigure 3

AI summary

An open wire detection system and method are provided. A semiconductor device includes a first diode having an anode terminal coupled to a first terminal and a cathode terminal coupled to a second terminal. The first and second terminals are configured for connection to a first battery cell terminal by way of a first conductive path and a second conductive path. A detect circuit is coupled to the first diode and is configured to provide a first open wire indication when a first voltage across the first diode exceeds a first threshold.