Leakage Current Diagnosis Using Dynamic Threshold Switching
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Solution Overview
Problem
Existing devices fail to accurately diagnose the state of a detection unit that determines leakage current in a high-voltage direct current power supply, leading to inaccuracies in leakage current detection.
Innovation Solution
A determining and diagnosing device that connects and disconnects a resistor to a power path and a predetermined location, using threshold values to determine leakage current occurrence and diagnose the detection unit's state by analyzing the detection value's time constant and rate of change.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the detection unit is diagnosed during the standby period following switch opening/closing control, then the state of the detection unit can be diagnosed, but determination of whether a leakage current is occurring cannot be performed during this period
Solution Approach 1:
The patent applies dynamics by making the threshold value dynamic rather than fixed. The determination threshold is changed based on the operational state (standby period vs. other periods), allowing the system to adapt its judgment criteria. During the standby period when diagnosis is performed, a different threshold is used that accounts for the diagnostic current, enabling both diagnosis and leakage current determination to occur simultaneously without conflict.
2Device complexity
If a fixed threshold value is used for leakage current determination, then the determination process is simple, but accurate determination cannot be made when diagnosing the detection unit during the standby period
Solution Approach 1:
The patent implements a dynamic threshold mechanism where the determination threshold varies based on the operational period. During the standby period when diagnosis is performed, the threshold is set to accommodate the diagnostic current flow. In other periods, a different threshold applies. This dynamic adjustment maintains measurement precision across different operational states while managing complexity through state-based threshold selection.
Solution Approach 2:
The patent changes the parameter (threshold value) based on the operational state. By switching between different threshold values depending on whether the system is in the standby period or other periods, the patent ensures accurate leakage current determination under varying conditions. This parameter change approach allows the system to maintain high measurement precision without requiring overly complex diagnostic procedures.
3Reliability
If the power path and predetermined location are connected via resistor during diagnosis control, then the detection unit state can be diagnosed, but floating capacitance discharge current interferes with leakage current determination
Solution Approach 1:
The patent applies dynamics by making the determination threshold dynamic rather than fixed. The determination threshold is changed based on the operational state (standby period vs. other periods), allowing the system to adapt its judgment criteria. During the standby period when diagnosis is performed, a different threshold is used that accounts for the diagnostic current, enabling both diagnosis and leakage current determination to occur simultaneously without conflict.
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 accurate determination of leakage current occurrence and diagnosis of detection unit abnormalities, ensuring reliable operation of the detection unit.
Implementation Method 1
a detection unit that detects a leakage current of a high-voltage direct current power supply that is installed in a vehicle, as a detection value of voltage
Implementation Method 2
a current due to discharge of the floating capacitance of the power path flows between the power path and the predetermined location. When the detection unit is normal, the detection value changes over a time constant due to the floating capacitance and the resistor
Data Source
AI summary
A determining and diagnosing device for determining whether a leakage current is generated based on a detection value from a detection unit that detects a current flowing between an power path and a predetermined location, and diagnosing a state of the detection unit, the device comprising: a connecting and disconnecting unit configured to connect and disconnect a resistor connected to the power path and a predetermined location; a determination diagnosis unit configured to determine whether a leakage current is generated based on the detection value and the first threshold value; and a determining and diagnosing unit configured to diagnose a state of the detection unit based on the detection value, the first threshold value, and a second threshold value that is different from the first threshold value, while executing a diagnosis control for controlling the connecting and disconnecting unit so that the power path and the predetermined location are connected.