EV Charging Circuit Insulation Fault Localization by Resistance Monitoring
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Solution Overview
Problem
Existing methods fail to distinguish between insulation faults originating from the vehicle's charging circuit or the charging station, leading to unnecessary replacement of vehicle components and increased costs, and do not effectively prevent oxidation-related risks during fast charging.
Innovation Solution
A method for detecting insulation faults in a battery pack charging circuit by measuring resistance during vehicle operation, allowing differentiation between faults on the vehicle and charging station sides, and preventing fast charging when oxidation is detected.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If insulation fault detection is performed during charging using existing methods, then fault detection capability is provided, but the method cannot distinguish between vehicle-side and charging station-side faults leading to unnecessary component replacements
Solution Approach 1:
The patent divides the charging circuit into two distinct segments: vehicle-side circuit (from battery pack to connector) and charging station-side circuit (from connector to charging device). By measuring resistance at different points and comparing values, the system can identify which segment contains the insulation fault, thereby segmenting the diagnostic process and eliminating unnecessary component replacements.
Solution Approach 2:
The patent utilizes resistance measurement as a key parameter to detect insulation faults. By measuring resistance values during charging operation and comparing them against threshold values, the system can identify insulation degradation or oxidation issues. This parameter-based approach enables precise fault detection without requiring physical disassembly or component replacement.
2Reliability
If connector routing is modified to prevent water entry, then oxidation risk is reduced, but cable thickness and vehicle ground clearance constraints make this difficult to implement
Solution Approach 1:
Instead of modifying the mechanical routing of the cable to prevent water entry, the patent substitutes a monitoring approach using resistance measurement. The system detects oxidation or water contamination through electrical parameter changes rather than preventing water access mechanically, thereby avoiding the manufacturing complexity associated with cable routing modifications.
Solution Approach 2:
The charging circuit itself serves as the sensing mechanism for detecting oxidation or water contamination. The resistance measurement is performed using the existing charging current path, eliminating the need for separate sensors or complex monitoring systems. The system uses its own operational parameters to self-diagnose potential issues.
3Productivity
If fast charging is enabled without oxidation detection, then charging speed is maintained, but oxidation-related safety risks increase
Solution Approach 1:
The patent implements a feedback mechanism where resistance measurements during charging provide information about connector condition. Based on this feedback, the system can adjust charging parameters or alert the user to potential oxidation issues, thereby maintaining fast charging capability while monitoring for safety risks associated with oxidation.
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
Efficiently identifies insulation faults in the vehicle's charging circuit, reducing unnecessary component replacements and preventing oxidation-related risks, thereby enhancing safety and reducing costs.
Implementation Method 1
During the detection operation, the management means measures a current I and a voltage U in the charging circuit to determine a resistance R according to the relation R=U/I. An insulation fault in the charging circuit is detected when the measured resistance R is less than or equal to a threshold resistance value Rs.
Data Source
Figure 1
AI summary
The invention relates to a method for monitoring an isolation defect in a recharging circuit (C1, C2) of a battery pack (1) of an electric vehicle comprising a battery module (2) which is capable of being connected to the electric motor by a discharging circuit (D1, D2) which comprises a first set of contactors (K1, K2), and is capable of being connected to a recharging base (4) by the recharging circuit which comprises a second set of contactors (K3, K4), the recharging base being intended to be connected to a recharging plug (3) of an electrical recharging device (8) for recharging the battery module (2). The method comprises an operation of detecting the isolation defect in the recharging circuit during a running phase of the vehicle, during which the second set of contactors is closed in order to electrically connect the battery module to the recharging base.