EV Charging Interlock Failure Detection Using Dual Comparators

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Solution Overview

Problem

Conventional electric vehicle failure mode detectors fail to accurately detect circuit failures, particularly in high-voltage interlock modules, and require frequent replacement of fuses, leading to inefficiencies and incomplete diagnosis.

Innovation Solution

A circuit failure detector using first and second comparators to differentially detect circuit failures through output signals, identifying states such as open, battery-short, GND-short, and frequency anomalies, with a controller to manage these states and a relay circuit to prevent further damage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a fuse is used to detect circuit failures, then overcurrent protection is provided, but the fuse must be replaced frequently and cannot detect all failure modes

Engineering Contradiction:

Improvecircuit failure detection capabilityVSAvoidmaintenance complexity

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The patent replaces the mechanical fuse-based detection system with an electronic detection system using comparators that electrically monitor circuit parameters. The first comparator detects battery short conditions by monitoring voltage levels, while the second comparator detects ground short conditions, eliminating the need for physical fuse replacement and enabling comprehensive failure mode detection.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If a single detection method is used, then the detection circuit is simple, but it cannot differentiate between various failure modes

Engineering Contradiction:

Improvefailure mode differentiationVSAvoiddetection circuit structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent segments the detection function into two independent comparators, each responsible for detecting specific failure modes. The first comparator is dedicated to detecting battery short conditions, while the second comparator detects ground short conditions. This segmentation enables precise failure mode differentiation while keeping each comparator's design relatively simple and modular.

Inventive Principle:

Principle #1Segmentation

3Reliability

If conventional one-way loop interrupt detection is used, then the detection method is simple, but it cannot detect all failure modes including battery short and ground short

Engineering Contradiction:

Improvefailure mode detection coverageVSAvoiddetection method complexity

Core Design Contradiction:

ReliabilityVSDifficulty of detecting and measuring

Solution Approach 1:

The patent introduces comparator circuits as intermediary detection devices that indirectly monitor circuit conditions by measuring voltage levels at specific points. The comparators act as mediators between the circuit under test and the control system, converting physical failure conditions (battery short, ground short) into detectable electrical signals that indicate the presence and type of failure.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 detector provides comprehensive failure mode detection, reduces repair costs by eliminating the need for fuses, and ensures safe operation by autonomously managing circuit failures without additional parts, allowing for efficient and module-independent integration.

Implementation Method 1

a first comparator that outputs a high voltage signal or a low voltage signal by comparing the corrected detection signal with a first reference voltage

Methodology Applied

Scientific EffectVoltage comparison:

Implementation Method 2

a second comparator that inverts the corrected detection signal and outputs a high voltage signal or a low voltage signal by comparing the inverted detection signal with a second reference voltage

Methodology Applied

Scientific EffectVoltage comparison and inversion:

Implementation Method 3

a first coupler that couples the output signal of the first comparator, and a second coupler that couples the output signal of the second comparator

Methodology Applied

Scientific EffectSignal coupling:

Data Source

PatentEP4224184B1Circuit failure detector, electric vehicle charging controller including same, and circuit failure detection method

Publication Date: 2025.12.31 LG INNOTEK CO LTD

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AI summary

The present invention relates to a circuit failure detector comprising: an input terminal for receiving a detection signal having a first frequency from an interlock circuit; a correction circuit for correcting the voltage of the received detection signal; a first comparator comparing the corrected detection signal with a first reference voltage and outputting a high voltage signal or a low voltage signal; a second comparator inverting the corrected detection signal, comparing the inverted detection signal with a second reference voltage, and outputting the high voltage signal or the low voltage signal; a counting signal generator for generating a counting signal having a second frequency; a first coupler for coupling an output signal of the first comparator with the counting signal; a second coupler for coupling the output signal of the second comparator with the counting signal; and a controller for detecting a circuit failure on the basis of the output signal of the first coupler and the output signal of the second coupler.