Load Drive Output Diagnosis Before Capacitor Voltage Stabilizes
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Solution Overview
Problem
Existing load drive devices face challenges in diagnosing Open-Load and Short-to-GND failures at the output terminal before the charging voltage stabilizes, due to the connection of a capacitor for noise resistance, which delays failure detection.
Innovation Solution
A load drive device configuration with a capacitor connected between the load terminal and ground, utilizing a diagnosis circuit that diagnoses failures based on current flowing between an internal power supply and the load terminal, allowing for rapid and accurate detection of terminal states.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a capacitor is connected between the output terminal and ground to improve noise resistance, then the reliability is improved, but the failure detection time is delayed because the charging voltage takes time to stabilize
Solution Approach 1:
The patent divides the detection function into two independent circuits: a voltage-based diagnosis circuit for normal operation and a current-based diagnosis circuit for rapid failure detection. This segmentation allows each circuit to operate independently with its own optimal characteristics, enabling both noise resistance and fast detection without mutual interference.
Solution Approach 2:
The patent introduces a switching element as an intermediary that selectively connects either the voltage-based diagnosis circuit or the current-based diagnosis circuit to the output terminal. This switching mechanism enables rapid transition between detection modes, allowing the system to quickly detect failures before the capacitor charging voltage stabilizes, while still maintaining noise resistance through the capacitor.
2Device complexity
If voltage comparison method is used for failure diagnosis, then the diagnosis circuit is simple, but the failure cannot be detected until the capacitor charging voltage stabilizes
Solution Approach 1:
The patent implements preliminary failure detection by using the current-based diagnosis circuit to detect failures immediately after a failure occurs, before the capacitor charging voltage has time to stabilize. This preliminary action captures the failure state at the earliest possible moment, avoiding the detection delay inherent in voltage-based methods.
Solution Approach 2:
The patent changes the detection parameter from voltage to current in the current-based diagnosis circuit. By monitoring current flow instead of voltage, the system can detect failures instantly without waiting for the capacitor to charge, as current changes occur immediately upon failure while voltage changes are delayed by the capacitor's charging time constant.
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 quick and accurate detection of normal, Open-Load, or Short-to-GND states at the load terminal before the capacitor's charging voltage stabilizes, improving reliability and enabling timely failure diagnosis.
Implementation Method 1
a capacitor is connected between a load terminal and a ground terminal
Implementation Method 2
the presence or absence of a failure of the load terminal is diagnosed on the basis of a current flowing between an internal power supply included in a diagnosis circuit and the load terminal
Data Source
AI summary
Provided is a load drive device capable of diagnosing a failure of an output terminal of the load drive device before a charging voltage stabilizes in a configuration in which a capacitor is connected to an output terminal of the load drive device that drives an inductive load. In the load drive device according to the present invention, a capacitor is connected between a load terminal and a ground terminal, and the presence or absence of a failure of the load terminal is diagnosed on the basis of a current flowing between an internal power supply included in a diagnosis circuit and the load terminal.