Battery Protection Circuit Using Temperature Sensor and Switching Element

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Solution Overview

Problem

Lithium-ion secondary batteries are prone to swelling, inflammation, or detonation due to exposure to high temperatures or internal defects, and existing solutions like PTC resistors are inadequate in addressing heat generation from external environment changes and internal shorts.

Innovation Solution

A protection apparatus using a temperature sensor, such as a negative temperature coefficient (NTC) thermistor or metal insulator transition (MIT) thermistor, in conjunction with a switching element like a transistor or thyristor, to detect and respond to elevated temperatures by forcibly discharging the battery, preventing further heat buildup and potential hazards.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a PTC resistor is used to prevent overcharge heating, then charging protection is improved, but protection against external heat and internal shorts is insufficient

Engineering Contradiction:

Improvecharging protectionVSAvoidprotection coverage

Core Design Contradiction:

ReliabilityVSAdaptability or versatility

Solution Approach 1:

The patent employs a temperature sensor (NTC thermistor or MIT thermistor) that serves multiple protective functions simultaneously: detecting overheating from overcharge, external environmental heat, and internal shorts. This single component provides universal protection across all heat generation scenarios, resolving the limitation of PTC resistors that only address overcharge protection

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Object-affected harmful factors

If the battery is discharged to prevent swelling and inflammation, then safety is improved, but energy loss occurs

Engineering Contradiction:

Improveswelling and inflammation preventionVSAvoidbattery discharge

Core Design Contradiction:

Object-affected harmful factorsVSLoss of energy

Solution Approach 1:

The temperature sensor detects temperature elevation before it reaches dangerous levels that would cause swelling, inflammation, or detonation. By triggering discharge at early warning temperatures, the system prevents harmful effects from developing while minimizing energy loss, rather than waiting for critical failure conditions

Inventive Principle:

Principle #9Preliminary anti-action

Solution Approach 2:

The temperature sensor continuously monitors battery temperature and provides feedback to the switching element. When temperature exceeds the predetermined threshold, the feedback loop activates the switching element to discharge the battery, creating a closed-loop control system that dynamically responds to thermal conditions and stops when temperature normalizes

Inventive Principle:

Principle #23Feedback

3Reliability

If a temperature sensor and switching element are used for protection, then comprehensive temperature protection is achieved, but device complexity increases

Engineering Contradiction:

Improvetemperature protectionVSAvoidprotection circuit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent uses a temperature sensor as an intermediary component that converts complex thermal conditions into a simple electrical signal that can directly control the switching element. This intermediary approach simplifies the overall control logic while maintaining comprehensive protection, avoiding the need for complex microcontrollers or multiple sensing circuits

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

Effectively stabilizes the electrolytic solution and prevents inflammation or detonation by discharging the battery when exposed to high temperatures or experiencing internal shorts, providing a simple and effective protection mechanism.

Implementation Method 1

the temperature sensor may include a negative temperature coefficient (NTC) thermistor or a metal insulator transition (MIT) thermistor

Methodology Applied

Scientific EffectNegative temperature coefficient (NTC): Thermistor

Implementation Method 2

the temperature sensor may include a negative temperature coefficient (NTC) thermistor or a metal insulator transition (MIT) thermistor

Methodology Applied

Scientific EffectMetal insulator transition (MIT):

Implementation Method 3

a switching element connecting both terminals of the secondary battery and forcibly discharging the second battery according to the control current

Methodology Applied

Scientific EffectElectrical conduction: Conduction (electrical)

Data Source

PatentUS8673469B2Apparatus for protection of secondary battery

Publication Date: 2014.03.18 LG ENERGY SOLUTION LTD

AI summary

The present invention is an apparatus for protecting a secondary battery, in which, when the secondary battery such as a lithium-ion secondary battery is exposed to high temperature exceeding a working range due to a change in external environment, external impacts, and so on, or heated due to spontaneous generation of heat caused by internal defects, the secondary battery is discharged. The apparatus includes a thyristor or transistor having an anode and a cathode connected both terminals of the secondary battery respectively, and shorting both terminals of the secondary battery when gate current is supplied, and a temperature sensor detecting temperature of the secondary battery and supplying the gate current to the thyristor or transistor when the detected temperature is higher than predetermined temperature.