Vehicle Battery Latch Relay Cutoff During BMS Sleep or Failure

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Solution Overview

Problem

Existing battery management systems (BMS) in electric vehicles and energy storage systems cannot effectively prevent thermal runaway of batteries when the battery monitoring IC (BMIC) or micro controller unit (MCU) fails or is in a sleep state, as they cannot turn off the latch relay in such scenarios.

Innovation Solution

An apparatus and method that utilize a latch relay connected between the vehicle battery and a low voltage DC-DC converter, activated by voltage inputs and outputs, and equipped with a controller that detects battery failures based on a reference voltage from a low dropout (LDO) regulator, allowing the latch relay to be turned off even when the BMIC or MCU is in a sleep state or has failed.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a conventional BMS with BMIC and MCU is used to monitor battery status, then battery monitoring function is provided, but the system cannot turn off the latch relay when BMIC or MCU fails or is in sleep state

Engineering Contradiction:

Improvebattery protection reliabilityVSAvoidBMS structure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent divides the battery protection function into two independent parts: the conventional BMS (BMIC+MCU) for normal monitoring, and a separate protection circuit with voltage comparator for critical latch relay control. This segmentation ensures that the protection function remains independent and operational even when the main BMS fails or is in sleep mode, resolving the contradiction between reliability and system complexity.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces a voltage comparator circuit as an intermediary component between the battery voltage and the latch relay control. This intermediary independently monitors battery voltage through a voltage divider and directly controls the latch relay based on preset thresholds, bypassing the need for BMIC/MCU intervention and ensuring reliable protection regardless of BMS operational state.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Ease of operation

If the BMS is simplified to reduce complexity, then manufacturing and operation become easier, but the ability to detect and respond to battery failures is reduced

Engineering Contradiction:

Improvesystem operation simplicityVSAvoidbattery failure detection capability

Core Design Contradiction:

Ease of operationVSReliability

Solution Approach 1:

The protection circuit is designed to be self-sufficient, using a voltage divider network and voltage comparator that automatically monitor battery voltage and control the latch relay without requiring external control signals from the BMS. This self-service mechanism ensures simple operation while maintaining reliable failure detection and response capabilities.

Inventive Principle:

Principle #25Self-service

3Adaptability or versatility

If the latch relay control is dependent on BMIC and MCU, then the control logic can be sophisticated, but the system becomes vulnerable to single point of failure

Engineering Contradiction:

Improvecontrol logic flexibilityVSAvoidsystem vulnerability to component failure

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent implements a redundant protection mechanism that cushions against potential BMS failures. The voltage comparator circuit is pre-configured with preset voltage thresholds and is ready to immediately control the latch relay if battery voltage exceeds safe limits, providing a safety buffer that prevents thermal runaway even when the main BMS is unavailable.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 solution enables continuous monitoring and protection of the vehicle battery, preventing thermal runaway by ensuring the latch relay can be turned off in case of battery failures, even if the BMIC or MCU is unavailable.

Implementation Method 1

a controller that is activated by a voltage input to the latch relay and a voltage output from the latch relay, detects a failure of the battery based on a reference voltage generated by a low dropout (LDO) regulator

Methodology Applied

Scientific EffectVoltage regulation:

Implementation Method 2

a latch relay that electrically connects or disconnects the battery and a converter provided in a vehicle

Methodology Applied

Scientific EffectElectromagnetic actuation: Electromagnet

Data Source

PatentUS20250192582A1Apparatus for protecting vehicle battery and method thereof

Publication Date: 2025.06.12 HYUNDAI MOTOR CO LTD

AI summary

An embodiment apparatus for protecting a battery of a vehicle includes a latch relay configured to electrically connect or disconnect the battery and a converter in the vehicle and a controller configured to be activated by a voltage input to the latch relay and a voltage output from the latch relay, detect a failure of the battery based on a reference voltage generated by a low dropout regulator, and control the latch relay to electrically disconnect the battery and the converter in response to detection of the failure of the battery.