Overcurrent Detection Circuit with Erroneous Detection Prevention

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Solution Overview

Problem

Existing overcurrent detection systems in energy storage apparatuses are prone to erroneous overcurrent detection due to connection failures in voltage detection lines, leading to unnecessary shutdowns and power supply disruptions caused by noise or noise-induced high impedance states.

Innovation Solution

Incorporating an erroneous detection prevention unit with a high-resistance resistor between the connection portions of the current detection circuit to prevent abnormal increases in potential difference, thereby reducing the likelihood of overcurrent detection errors.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If a current detector uses a sense resistor and comparator to detect current, then current detection capability is achieved, but connection failure in wiring lines causes high impedance state and erroneous overcurrent detection

Engineering Contradiction:

Improvecurrent detection accuracyVSAvoiddetection system reliability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent applies preliminary action by introducing a pull-down resistor connected to the negative terminal of the sense resistor before any connection failure occurs. This resistor is pre-configured to provide a reference potential and prevent high impedance states, ensuring that even if wiring lines fail, the detection system maintains stable voltage levels and avoids erroneous overcurrent detection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The pull-down resistor acts as an intermediary element between the sense resistor and ground. It mediates the electrical connection by providing a controlled impedance path that prevents the high impedance state from developing when wiring lines experience connection failures, thus stabilizing the detection circuit without interfering with normal current measurement functionality.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If wiring lines are used to connect sense resistor to comparator, then current detection is enabled, but noise on wiring lines causes large voltage difference and erroneous overcurrent detection

Engineering Contradiction:

Improvecurrent detection implementationVSAvoidnoise interference

Core Design Contradiction:

Ease of operationVSObject-affected harmful factors

Solution Approach 1:

The patent converts the potentially harmful effect of noise on wiring lines into a beneficial configuration by using the pull-down resistor to establish a defined reference potential. Instead of trying to eliminate noise entirely, the design accepts noise presence but ensures it cannot create erroneous voltage differences large enough to trigger false overcurrent detection, as the pull-down resistor clamps the voltage to a safe range.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Reliability

If a current shutoff device is installed based on comparator output, then overcurrent protection is achieved, but erroneous detection causes unnecessary shutdowns and power supply disruption

Engineering Contradiction:

Improveovercurrent protection reliabilityVSAvoidpower supply continuity

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The pull-down resistor performs preliminary protection by preventing the conditions that lead to erroneous detection before they can trigger the current shutoff device. By establishing a stable reference potential in advance, it ensures that the comparator receives accurate voltage signals, thereby preventing false shutdown commands and maintaining uninterrupted power supply while still providing genuine overcurrent protection.

Inventive Principle:

Principle #10Preliminary action

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

Prevents erroneous overcurrent detection and maintains power supply by ensuring the potential difference remains within a predetermined value, even in the presence of connection failures or noise, thus avoiding unnecessary shutdowns.

Implementation Method 1

a current detection resistor that is connected in series to a main circuit and causes a potential difference at both ends according to a current flowing through the main circuit

Methodology Applied

Scientific EffectOhm's Law: Ohm's Law

Implementation Method 2

an erroneous detection prevention unit connected between the pair of connection portions in the current detection circuit

Methodology Applied

Scientific EffectElectrical Resistance: Electrical Resistance

Data Source

PatentUS11322925B2Overcurrent detection device, energy storage apparatus, and current detection method

Publication Date: 2022.05.03 GS YUASA INT LTD

AI summary

An overcurrent detection device including: a current detection resistor that is connected in series to a main circuit and is configured to cause a potential difference at both ends according to a current flowing through the main circuit; a current detection circuit that includes a pair of connection portions and is configured to detect a potential difference between the pair of connection portions; a pair of voltage detection lines connecting the both ends of the current detection resistor to the pair of connection portions in the current detection circuit; and an erroneous detection prevention unit configured to prevent an increase in the potential difference between the pair of connection portions when at least any one of the pair of voltage detection lines has a connection failure.