Battery Module Protection Circuit for MCU Endless-Loop Failures
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Solution Overview
Problem
In battery management systems, a microcontroller entering an endless loop can lead to uncontrolled charging or discharging, causing battery damage or thermal runaway due to the inability to reset the watchdog timer, and existing solutions like external ASIC watchdog timers may not effectively prevent repeated switching issues.
Innovation Solution
A protection circuit with a master microcontroller, slave microcontroller, switch controller, charging path switch, and discharging path switch, where the slave microcontroller disables the switch controller if it doesn't receive a pulse signal from the master, preventing charging or discharging when the master is abnormal, and a system restart procedure is performed to restore normal operation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a single microcontroller is used to control charging and discharging paths, then the device complexity is reduced, but the reliability deteriorates when the microcontroller enters an endless loop
Solution Approach 1:
The control system is segmented into a master microcontroller and a slave microcontroller. The master microcontroller handles normal control operations while the slave microcontroller monitors the master's status and takes over control when the master fails, thereby improving reliability without significantly increasing overall system complexity.
Solution Approach 2:
The slave microcontroller acts as an intermediary between the master microcontroller and the switch controller. It monitors the master's pulse signals and intervenes by disabling the switch controller when the master fails, preventing uncontrolled charging or discharging.
2Reliability
If an external ASIC watchdog timer is used to reset the microcontroller, then the reliability is improved, but the harmful factors worsen due to repeated switching
Solution Approach 1:
The slave microcontroller continuously receives pulse signals from the master microcontroller as feedback. When the pulse signal stops (indicating master failure), the slave activates and disables the switch controller, preventing repeated switching and the associated harmful effects on the battery module.
Solution Approach 2:
The slave microcontroller is pre-configured to disable the switch controller when master failure is detected. This preliminary anti-action prevents the harmful effects of uncontrolled switching before they can occur, rather than merely resetting the microcontroller after failure.
3Reliability
If the switch controller is kept in disabled state for a fixed time, then the reliability is improved, but the productivity deteriorates due to charging/discharging interruption
Solution Approach 1:
The switch controller's enabled/disabled state is dynamically adjusted based on the operational status of the master microcontroller. When the master is functioning normally, the switch controller remains enabled for efficient charging/discharging. When the master fails, the slave disables the switch controller to prevent harmful operations, and the system can be restarted when appropriate.
Data Source
AI summary
This disclosure provides a protection circuit of a battery module. The protection circuit includes a master microcontroller, a slave microcontroller, a charging path switch, a discharging path switch, and a switch controller. When the master microcontroller is operating in a normal state, the master microcontroller periodically sends a pulse signal to the slave microcontroller, and enables the switch controller, and then the switch controller enabled may be used to control the turning on or off of the charge path switch or the discharge path switch. When the master microcontroller is operating in an abnormal state, the slave microcontroller does not receive the pulse signal from the master microcontroller, the slave microcontroller disables the switch controller so that the switch controller disabled will be unable to control the turning on or off of the charge path switch or the discharge path switch.