Starter Circuit Fault Detection Using Battery Voltage Drop
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Solution Overview
Problem
Existing engine starting devices lack the ability to identify the location of fault occurrence in the inrush current limit circuit, which affects battery voltage and starter motor operation.
Innovation Solution
Incorporating a fault identification unit that analyzes the minimum battery voltage and voltage decrease when the bypass relay's normally open contact is actuated, allowing for the identification of faults in the inrush current limit circuit by comparing these values against predetermined thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an inrush current limit circuit with a bypass relay is used to suppress battery voltage decrease during engine startup, then the battery voltage stability is improved, but the ability to identify fault location in the circuit is deteriorated
Solution Approach 1:
The system performs preliminary diagnostic actions by measuring battery voltage at specific moments (when starter motor is activated and when bypass relay switches) before actual engine operation begins. These preliminary measurements establish baseline data that enables subsequent fault location identification without interfering with normal engine starting operations.
Solution Approach 2:
The control unit continuously monitors battery voltage and provides feedback by comparing measured voltage values against expected ranges. When voltage deviations occur during starter motor operation or bypass relay switching, the system uses this feedback to identify fault locations in the inrush current limit circuit, thereby maintaining both voltage stability and diagnostic capability.
2Reliability
If the bypass relay contact is closed after a predetermined time to reduce voltage decrease, then the voltage stability is improved, but the complexity of monitoring and diagnosing circuit faults increases
Solution Approach 1:
The control unit performs multiple functions using a single diagnostic approach: it manages engine starting control, monitors battery voltage stability, and identifies fault locations in the inrush current limit circuit. By making the control unit multi-functional, the system avoids adding separate diagnostic hardware, thereby reducing overall system complexity while maintaining comprehensive monitoring capabilities.
Data Source
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AI summary
An engine starting device in which an inrush current limit circuit (25), comprising a resistor (23) and a bypass relay (24) connected in parallel, is interposed between a battery (22) and a starter motor (21), and a normally open contact (26) of the bypass relay (24) is closed at the time of engine startup, wherein the engine starting device is provided with a fault identification unit (29) for identifying a fault pattern on the basis of the minimum voltage of the battery (22) while the starter motor is in operation (battery voltage minimum value A) and the amount of decrease in the voltage of the battery (22) when the normally open contact (26) is actuated in a closing direction (battery voltage recorded value B - battery voltage minimum value C).