Watchdog Timer Diagnosis via Invalid Trigger Injection
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Solution Overview
Problem
The existing watchdog timer systems fail to accurately diagnose and recover from malfunctions in battery management systems, posing safety risks due to incorrect operation or inability to detect malfunctions.
Innovation Solution
An apparatus and method involving a DC-DC voltage converter and a control unit with specific communication terminals, which outputs operating voltage and diagnosis signals to diagnose the watchdog timer, storing data on malfunctions and preventing abrupt power shutdowns, utilizing an opto-coupler for external device communication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a watchdog timer is used to detect and recover from BMS malfunctions, then system reliability is improved, but the complexity of the system increases due to additional diagnostic components and control logic
Solution Approach 1:
The system is divided into distinct functional modules: a DC-DC voltage converter module that provides controlled power output, a control unit with specific terminals (hold, trigger, reset), and a diagnostic module. This segmentation allows each component to have a specialized function, making the overall complex system manageable and maintainable while ensuring reliable watchdog timer operation.
Solution Approach 2:
The patent introduces an intermediary diagnostic system between the BMS and the watchdog timer. The control unit acts as a mediator that generates invalid trigger signals under controlled conditions and monitors the watchdog timer's response. This intermediary layer enables precise diagnostic capability without requiring direct modification of the core BMS architecture, thus managing complexity while improving reliability.
2Device complexity
If the watchdog timer operates without proper diagnosis, then device complexity is reduced, but measurement precision of malfunction detection deteriorates
Solution Approach 1:
The system performs preliminary diagnostic actions by generating invalid trigger signals before actual malfunction scenarios occur. The control unit proactively tests the watchdog timer's response to abnormal conditions by injecting predetermined invalid triggers, allowing the system to verify detection precision in advance without waiting for actual malfunctions. This preliminary testing ensures measurement precision while maintaining relatively simple operational complexity.
Solution Approach 2:
The diagnostic system is self-service in nature, where the control unit automatically generates test signals and evaluates the watchdog timer's response without requiring external intervention. The system stores diagnostic results in its own memory and can communicate results through existing communication terminals. This self-diagnostic capability improves detection precision while avoiding the complexity of external diagnostic equipment.
3Measurement precision
If the control unit outputs hold signal and invalid trigger signal simultaneously, then diagnosis capability is improved, but loss of time occurs due to shutdown mode activation
Solution Approach 1:
The diagnostic operation is implemented as a periodic, time-limited action rather than a continuous state. The control unit outputs the hold signal and invalid trigger signal for a predetermined diagnostic period, then automatically terminates the diagnostic mode and restores normal operation. This periodic approach allows sufficient time to complete the diagnosis and store results while minimizing time loss due to shutdown mode, as the diagnostic action is confined to specific time intervals rather than being prolonged.
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
Enables effective diagnosis and recovery of watchdog timer malfunctions, preventing safety issues by ensuring controlled shutdowns and accurate diagnosis of battery management system malfunctions.
Implementation Method 1
a DC-DC voltage converter including an enable terminal, a power input terminal and a power output terminal and configured to selectively output an operating voltage for the watchdog timer at the power output terminal based on an input voltage applied to the power input terminal
Data Source
AI summary
An apparatus and method for diagnosing a watchdog timer is provided. The watchdog timer is used to detect and recover from a malfunction of a battery management system. Before entering a shutdown mode in response to a shutdown command from an external device, the apparatus outputs an invalid trigger signal to the watchdog timer and diagnoses a malfunction of the watchdog timer depending on whether the watchdog timer outputs a reset signal.