Vehicle Power Supply Abnormality Detection Circuit
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Solution Overview
Problem
Existing vehicle-mounted power supply devices face increased processing loads during failure diagnosis and cannot determine the operational status of critical components like monitor circuits and protection circuits, affecting normal operation.
Innovation Solution
An abnormality detection device that includes a detection circuit unit, a protection circuit unit, and an abnormality determination unit to diagnose and determine the abnormality of these components by generating analog signals for current and voltage, converting them to digital signals, and performing predetermined protection operations based on abnormal values in input and output paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If failure diagnosis is performed during normal voltage conversion, then switching element failure can be detected, but processing load increases affecting normal operation
Solution Approach 1:
The system performs failure diagnosis during periods when the voltage converting unit is not operating (e.g., during engine cranking or when auxiliary power is sufficient), preparing diagnostic data in advance without interfering with normal voltage conversion operations. This separates the timing of diagnosis from normal operation, eliminating processing load conflicts.
Solution Approach 2:
The diagnosis function is segmented into independent phases: voltage conversion operation, diagnosis execution phase, and result determination phase. The control unit manages these as separate operational modes, allowing full-speed voltage conversion during normal operation and dedicated diagnosis during transition periods, thus avoiding processing load interference.
2Device complexity
If only switching element failure is detected, then simple diagnosis is possible, but circuits like monitor circuit and protection circuit cannot be determined to be operating properly
Solution Approach 1:
The control unit serves multiple functions: it controls the voltage converting unit during normal operation, executes comprehensive diagnosis during idle periods, and determines abnormality results. This multi-functional design allows the same hardware to perform both simple switching element detection and comprehensive circuit functionality verification without requiring separate dedicated hardware for each function.
Solution Approach 2:
The system implements feedback loops where the control unit monitors not only switching element states but also the operational responses of monitor circuits and protection circuits. By analyzing feedback signals from these circuits during diagnosis mode, the system can determine whether they are operating properly while maintaining the same basic diagnostic hardware structure.
3Loss of time
If diagnosis operation is performed during vehicle operation, then real-time abnormality detection is possible, but normal vehicle operation is affected
Solution Approach 1:
The system performs comprehensive diagnosis periodically during predetermined periods when the voltage converting unit is not operating, such as during engine cranking or when the vehicle is in a low-power state. This periodic timing ensures that diagnosis occurs at regular intervals without continuously interfering with normal vehicle operation, maintaining both real-time detection capability and operational smoothness.
Data Source
AI summary
An abnormality detection device includes a detection circuit unit, a protection circuit unit, and an abnormality determination unit. The detection circuit unit includes: a voltage detection circuit and a current detection circuit that generate, as analog signals, detection values indicating a current and a voltage at a predetermined position of a vehicle-mounted power supply device. An A/D converter converts the detection value into a digital signal. The protection circuit unit performs a predetermined protection operation on the vehicle-mounted power supply device if a voltage or a current of an input path or an output path of a voltage converting unit has an abnormal value. The abnormality determination unit makes at least one of the detection circuit unit and the protection circuit unit perform a predetermined diagnosis operation, and determines, based on a result of the diagnosis operation, whether the detection circuit unit and the protection circuit unit is abnormal.