Insulation Abnormality Detection Using Stray Capacitance Elimination
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Solution Overview
Problem
Existing methods for detecting insulation abnormalities in vehicles are not accurate enough, particularly due to increased stray capacitance and decreased insulation resistance values, which can cause malfunctions in complex control systems.
Innovation Solution
An insulation abnormality detection apparatus featuring a voltage detecting circuit with a capacitor and switches, where the controller forms an insulation measurement path, eliminates stray capacitance influence by charging and discharging the capacitor, and measures voltage after a predetermined time to detect insulation abnormalities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional insulation detection methods are used, then the detection process is simple, but the measurement precision is insufficient due to stray capacitance interference
Solution Approach 1:
The patent segments the insulation detection process into distinct phases: a first time period for eliminating stray capacitance influence by controlling specific switches, and a second time period for measuring insulation voltage. This temporal segmentation allows the circuit to perform different functions at different times, improving measurement precision while managing circuit complexity through structured control sequences.
Solution Approach 2:
The patent applies preliminary action by performing stray capacitance elimination before the actual insulation measurement. During the first time period, the controller executes preliminary operations to remove the influence of stray capacitance from the capacitor, ensuring that the subsequent measurement in the second time period is not affected by this interference, thereby improving measurement accuracy.
2Reliability
If insulation measurement is performed continuously, then real-time monitoring is achieved, but energy consumption increases
Solution Approach 1:
The patent implements periodic action by conducting insulation measurements at predetermined intervals rather than continuously. The battery ECU performs insulation abnormality detection at specific timing, which reduces energy consumption compared to continuous monitoring while still maintaining reliable detection capability. This periodic measurement approach balances reliability requirements with energy efficiency in hybrid vehicles.
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
This approach allows for accurate detection of insulation abnormalities by isolating the influence of stray capacitance, reducing costs, and improving the reliability of insulation resistance measurements.
Implementation Method 1
a capacitor (C1) connected in parallel to the battery (2) and having first and second electrodes
Implementation Method 2
when an abnormality that a resistance value of an insulation resistance of the vehicle body decreases occurs
Data Source
AI summary
A controller (1) forms an insulation measurement path and turns on a third switch connected in parallel to a capacitor, (2) after a lapse of a first time period turns off the third switch, and (3) detects an insulation abnormality based on a voltage of the capacitor measured after a lapse of a second time period after the turning off of the third switch.