Switching Circuit Failure Detection Using Capacitor Voltage Timing
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Solution Overview
Problem
Existing vehicular control devices with semiconductor switches in parallel circuits face challenges in quickly diagnosing failures when a capacitor is connected, as it takes time for the capacitor to discharge, delaying the determination of switching circuit functionality.
Innovation Solution
A control device with a voltage detection unit and a control unit that determines switching circuit failure by detecting voltage changes after a predetermined time elapsed from switching off, allowing for quicker failure determination without waiting for complete capacitor discharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a capacitor with large capacity is connected to the circuit to be controlled, then the energy storage capability is improved, but the discharge time increases and delays failure diagnosis
Solution Approach 1:
The control unit performs failure determination at a predetermined time point after switching off, before the capacitor is completely discharged. This preliminary action allows diagnostic information to be captured while the capacitor still retains charge, enabling faster diagnosis without waiting for full discharge.
Solution Approach 2:
The capacitor's residual charge at the predetermined time point is utilized as a useful indicator for failure determination. Instead of waiting for complete discharge, the system leverages the capacitor's natural discharge characteristic at a specific time point to determine switching circuit status, turning what would be wasted time into a diagnostic opportunity.
2Measurement precision
If the switching circuit is controlled to turn off and wait for complete capacitor discharge, then the failure determination accuracy is improved, but the diagnostic time increases
Solution Approach 1:
The control unit determines failure status at a predetermined time point before complete discharge occurs. This timing allows the system to capture voltage information that is still distinguishable and useful for accurate failure determination, while avoiding the lengthy wait for full discharge.
Solution Approach 2:
The invention changes the temporal parameter of measurement from 'after complete discharge' to 'at predetermined time during discharge'. By measuring voltage at this intermediate time point, the system achieves sufficient diagnostic accuracy while significantly reducing the time required compared to waiting for complete discharge.
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 rapid identification of switching circuit failures, including short and open circuit conditions, without requiring complete capacitor discharge, thereby reducing diagnostic time and improving operational efficiency.
Implementation Method 1
a voltage detection unit configured to detect a voltage of the one end portion
Data Source
AI summary
Provided is a vehicular control device that is provided with a switching circuit, and for opening/closing a connection between a starter including a capacitor that is to be connected to one end portion of the switching circuit and an in-vehicle battery that is to be connected to another end portion of the switching circuit by controlling an on/off state of the switching circuit. The control device includes a voltage detection unit configured to detect a voltage of the one end portion, and a control unit configured to control the switching circuit to turn off from on, and determine whether there is a failure in the switching circuit, based on a voltage detected by the voltage detection unit when a predetermined time has elapsed from when the switching circuit is controlled to turn off from on.