Insulation Fault Location in Vehicle Battery Using Resistive Branch
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Solution Overview
Problem
Current methods for determining insulation faults between an electrical circuit and the vehicle mass in electric vehicles do not provide precise location of faults within the accumulator battery, and existing systems require physical connections to each battery element.
Innovation Solution
A non-intrusive method involving measurements between battery terminals and ground using resistive branches to establish equations for determining insulation resistance and fault position, with a device that automatically modifies connections and includes protective resistors to prevent short-circuits.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a physical connection is made between each battery element to locate insulation faults, then the fault location precision is improved, but the device complexity and ease of operation deteriorate
Solution Approach 1:
The patent extracts the essential measurement function from the complex physical connection system. By using a simplified measurement device that connects only to battery terminals rather than requiring physical connections to each battery element, the system achieves fault location capability with reduced device complexity while maintaining measurement precision.
Solution Approach 2:
The patent introduces an intermediary measurement approach where voltage measurements are taken at battery terminals through a resistive branch, rather than directly measuring at each battery element. This intermediary measurement method enables fault location without requiring direct physical connections to each element, thus reducing device complexity.
2Measurement precision
If physical connections are made to each battery element, then fault detection accuracy is improved, but the ease of operation deteriorates
Solution Approach 1:
The patent extracts the fault detection capability from the complex physical connection requirement. The measurement device only needs to connect to battery terminals, not each individual battery element, making the system easier to operate while maintaining accurate fault detection through voltage measurement analysis.
Solution Approach 2:
The patent enables the battery system to self-diagnose fault location through voltage measurements taken at terminals. The system uses the battery's own voltage characteristics and the measured voltage drops to automatically determine fault position without requiring manual physical connections to each element, thus improving ease of operation.
3Device complexity
If insulation resistance is measured without physical connection to each battery element, then device complexity is reduced, but measurement precision deteriorates
Solution Approach 1:
The patent uses voltage measurements as an intermediary to infer insulation resistance characteristics. By measuring voltages at battery terminals and analyzing the voltage drops through the resistive branch, the system achieves accurate measurement precision without requiring direct physical connections to each battery element, thus maintaining measurement quality with reduced device complexity.
Solution Approach 2:
The patent replaces the mechanical physical connection system with an electrical measurement system. Instead of requiring physical connections to each battery element, the system uses voltage measurements and electrical analysis to determine insulation resistance and fault location, achieving the same measurement precision through a different (simpler) approach.
4Reliability
If multiple resistive branches are connected in parallel, then the reliability of the measurement system is improved, but the device complexity increases
Solution Approach 1:
The patent applies partial action by using a single resistive branch for the primary measurement function. While multiple branches could be connected in parallel to improve reliability, the patent achieves sufficient reliability through careful selection and analysis of voltage measurements from the single branch, avoiding the added complexity of multiple parallel branches while maintaining adequate measurement reliability.
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 precise determination of insulation fault position and resistance without physical connection to each battery element, improving diagnostic accuracy and safety by automatically modifying measurement connections and using protective resistors.
Implementation Method 1
A measurement circuit comprising a first resistive branch of value R0 is then connected between the first terminal of the battery and ground and a voltage V2 measurement is carried out at the terminals of the first resistive branch. The insulation resistance is then estimated by the formula: Ri=R0.(V1-V2)/V2
Implementation Method 2
the voltage is measured between each of the battery terminals and the chassis of the vehicle. Suppose that the voltage V1 thus measured is the highest on the first terminal
Data Source
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AI summary
According to a method for determining the characteristics of an insulation fault between an electric circuit including an accumulator battery (2) in a motor vehicle and the vehicle ground (3), the battery (2) comprising first and second terminals (22) for supplying the circuit, measuring means comprising a first resistive branch (16) are connected between a first terminal 21 of the battery (2) and the ground (3), and a first measurement is taken representative of the current in the first resistive branch (16), a second measurement similar to the first measurement is taken by connecting the measuring means between the second terminal (22) of the battery (2) and the ground (3), and a position of an insulation fault inside the battery (2) is deduced from the relationship between the first and second measurements . A device taking such measurements.