Insulation Resistance Measurement Circuit Self-Diagnosis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for measuring insulation resistance in high-voltage systems, such as those in electric vehicles, suffer from reduced reliability due to the integration of mechanical or semiconductor switches and the need for two identical comparator resistors, which can affect measurement accuracy and reliability.
Innovation Solution
A circuit with two identical comparator resistors connected in series to the positive and negative terminals of the battery system, using switches for current measurement, calculates theoretical current flows, and compares them with measured values to detect errors in switches and resistors, ensuring accurate insulation resistance measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If mechanical or semiconductor switches are integrated into the measurement circuit to enable automated insulation resistance measurement, then the automation capability is improved, but the reliability of the measurement is worsened due to potential switch failures and additional error sources
Solution Approach 1:
The patent applies preliminary action by performing self-diagnosis measurements before the actual insulation resistance measurement to detect potential errors in switches and comparator resistors. The system proactively identifies faulty components through preliminary current measurements and compares them against reference values, preventing unreliable measurements from occurring in the first place.
Solution Approach 2:
The patent implements feedback by continuously monitoring the current flows through switches and comparator resistors, comparing measured values against theoretically calculated reference values, and using this information to diagnose errors. The system feeds back diagnostic information to determine whether components are functioning correctly before proceeding with measurement.
2Extent of automation
If two identical comparator resistors are provided and connected through switches to enable automated measurement, then the automation capability is improved, but the measurement precision is worsened due to potential variations in resistor values and switch contact resistance
Solution Approach 1:
The system performs preliminary measurements of current flows through each comparator resistor when its associated switch is closed, before conducting the actual insulation resistance measurement. This allows detection of resistor value variations or switch contact issues that would affect measurement precision.
Solution Approach 2:
The system continuously monitors current flows through the comparator resistors and switches, comparing measured values against reference values calculated from known component parameters. This feedback mechanism identifies deviations that indicate precision-degrading issues with resistors or switches.
3Reliability
If self-diagnosis functionality is added to detect errors in switches and resistors, then the reliability is improved, but the device complexity is worsened due to additional measurement circuits and processing requirements
Solution Approach 1:
The patent applies multi-functionality by using the existing measurement circuit components (amperemeter, switches, comparator resistors) to serve dual purposes: both performing the insulation resistance measurement and conducting self-diagnosis of the circuit components. The same hardware infrastructure is utilized for both measurement and diagnostic functions, avoiding additional dedicated diagnostic hardware.
Solution Approach 2:
The system performs self-service by automatically diagnosing its own components (switches and comparator resistors) using built-in measurement capabilities. The measurement circuit monitors itself, detecting errors in its own components without requiring external diagnostic equipment or manual testing.
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
The method enhances the reliability of insulation resistance measurements by detecting and correcting errors in switches and resistors, improving the accuracy and safety of the measurement process.
Implementation Method 1
a first switch, which connects the positive terminal of the battery system to earth via a series-connected first comparator resistor, and a second switch, which connects the negative terminal of the battery system to earth via a series-connected second comparator resistor
Data Source
AI summary
The invention relates to the self-diagnosis of a circuit for measuring the insulation resistance of a battery system, the circuit having a first switch, which connects the positive terminal of the battery system to earth via a series-connected first comparator resistor, and a second switch, which connects the negative terminal of the battery system to earth via a series-connected second comparator resistor. Current measurements are made via the closed first switch to obtain a measured first current flow and via the closed second switch to obtain a measured second current flow, wherein at any one time only one of the two switches closed, the theoretical current flow via the switches is calculated on the basis of the voltage of the battery system and the size of the comparator resistor, and the measured current flow, is compared with the associated theoretical current flow, wherein an error signal is output and/or an error action is carried out when the result of the comparison is above or below a predefined reference value range.