Low-Side Drive Circuit for Relay Hold During MCU Reset

Solution Overview

Problem

In electric vehicles, the potential unexpected reset of the microcontroller in the battery management system can cause safety hazards due to abrupt changes in the relay's on/off state, leading to unexpected vehicle stops and relay damage.

Innovation Solution

A drive circuit with a low-side driver module and a delay module is introduced, where the delay module outputs a preset duration delay signal to maintain the relay's state before the control module reset, ensuring the relay remains in its previous state during the reset, thus preventing abrupt state changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a relay is used as a switch controlled by a microcontroller, then the switching function is achieved, but unexpected reset of the microcontroller causes safety hazards and relay damage

Engineering Contradiction:

Improvesystem reliabilityVSAvoidsafety hazards from abrupt state changes

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The delay module is pre-configured to detect reset signals and automatically generate delay signals before the microcontroller completes its reset. This preliminary action maintains the relay in its original state during the reset period, preventing abrupt state changes that would cause safety hazards or relay damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The delay module acts as an intermediary between the microcontroller and the relay. When the microcontroller resets, the delay module intercepts the state change by generating a delay signal that keeps the relay in its original state, thereby mediating the harmful effect of the reset on the relay and system safety.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Adaptability or versatility

If the microcontroller resets during operation, then the control module can be reinitialized, but the relay state changes abruptly causing potential damage

Engineering Contradiction:

Improvecontrol module reinitialization capabilityVSAvoidrelay durability

Core Design Contradiction:

Adaptability or versatilityVSStrength

Solution Approach 1:

The delay module is pre-configured to detect reset signals and automatically generate delay signals before the microcontroller completes its reset. This preliminary action maintains the relay in its original state during the reset period, preventing abrupt state changes that would cause safety hazards or relay damage.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The delay module provides a cushioning effect by maintaining the relay in its original state during the microcontroller reset period. This beforehand cushioning prevents the abrupt state change that would otherwise occur, protecting the relay from potential damage while allowing the microcontroller to reinitialize.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

3Device complexity

If no delay mechanism is added, then the circuit remains simple, but the relay cannot maintain its state during microcontroller reset

Engineering Contradiction:

Improvecircuit complexityVSAvoidrelay state stability

Core Design Contradiction:

Device complexityVSReliability

Solution Approach 1:

The delay module acts as an intermediary between the microcontroller and the relay. When the microcontroller resets, the delay module intercepts the state change by generating a delay signal that keeps the relay in its original state, thereby mediating the harmful effect of the reset on the relay and system safety.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The delay module is self-contained with internal delay components that automatically generate the appropriate delay signal when a reset is detected. It does not require external control or additional complexity in the main control logic, providing state stability through its own internal mechanisms.

Inventive Principle:

Principle #25Self-service

Data Source

PatentUS12183527B2Drive circuit

Publication Date: 2024.12.31 CONTEMPORARY AMPEREX TECHNOLOGY (HONG KONG) LIMITED

AI summary

Embodiments of this application relate to the field of electricity, and disclose a drive circuit. In some embodiments of this application, the drive circuit includes a low-side driver module and a delay module, the delay module is configured to output a delay signal of preset duration to the low-side driver module in a case that a control module is being reset; and the low-side driver module is configured to: according to on the delay signal of preset duration, maintain a first state within the preset duration, the first state being the same as a second state; where the second state is a working state of the low-side driver module before the control module is reset, and the second state includes being on or off. The embodiments can help avoid safety hazards caused by unexpected disconnection of a drive signal of the control module.