EV Charging Plug Insulation Resistance Measurement Without Adapters

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Solution Overview

Problem

Existing methods for measuring the insulation resistance of high-voltage electrical systems in electric vehicles during workshop inspections are cumbersome, require specialized adapters, pose safety risks, and are affected by the vehicle's internal insulation monitoring device, making external measurements challenging and time-consuming.

Innovation Solution

Measure the insulation resistance by initiating a charging process using a standard charging plug, which simulates the connection of a charger to the vehicle, allowing the vehicle's switches to close and enabling safe, external measurement without adapters, using the vehicle's own insulation monitoring device.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of operation

If external measuring device is used to measure insulation resistance, then measurement can be performed during workshop inspection, but installation work is necessary and contact protection is lost creating safety risks

Engineering Contradiction:
Improvemeasurement accessibilityVSAvoidcontact protection
Core Design Contradiction:
Ease of operationVSReliability

Solution Approach 1:

The charging plug serves as an intermediary device that provides both measurement capability and inherent contact protection. By utilizing the existing charging infrastructure, the method enables safe external measurement without requiring direct exposure to high-voltage contacts, thus resolving the contradiction between measurement accessibility and contact protection.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The vehicle's own charging system and insulation monitoring device are utilized to perform the measurement. The charging plug initiates a charging process that automatically activates the vehicle's IMD, which then provides the measurement data. This self-service approach eliminates the need for external measuring devices and associated safety risks.

Inventive Principle:
Principle #25Self-service

2Measurement precision

If vehicle's internal insulation monitoring device is active during measurement, then measurement can be performed, but measured insulation resistance value becomes distorted or difficult to determine

Engineering Contradiction:
Improveinsulation resistance measurementVSAvoidmeasurement distortion
Core Design Contradiction:
Measurement precisionVSObject-generated harmful factors

Solution Approach 1:

The charging plug initiates the charging process before the actual insulation resistance measurement is performed. This preliminary action ensures that the vehicle's internal insulation monitoring device is properly activated and ready to provide accurate measurements, preventing measurement distortion that would occur if the device were inactive.

Inventive Principle:
Principle #10Preliminary action

Solution Approach 2:

The method utilizes the feedback mechanism of the vehicle's internal insulation monitoring device, which continuously monitors insulation resistance during charging. By reading this feedback data through the charging plug, the system obtains accurate real-time measurement values without distortion.

Inventive Principle:
Principle #23Feedback

3Device complexity

If standardized charging plug is used instead of vehicle-specific measuring adapter, then measurement becomes simpler and more universal, but requires initiating charging process

Engineering Contradiction:
Improvemeasuring equipmentVSAvoidmeasurement procedure
Core Design Contradiction:
Device complexityVSEase of operation

Solution Approach 1:

The standardized charging plug serves multiple functions: it provides physical connection to the vehicle, initiates the charging process to activate the insulation monitoring device, and enables the measurement of insulation resistance. This multi-functionality eliminates the need for vehicle-specific adapters and simplifies the measurement equipment requirements.

Inventive Principle:
Principle #6Universality (Multi-functionality)

Solution Approach 2:

The measurement function is merged with the existing charging function. By combining these two operations, the method uses a single standardized charging plug for both charging and insulation resistance measurement, reducing device complexity and eliminating the need for separate measuring adapters.

Inventive Principle:
Principle #5Merging (Combining)

Data Source

PatentEP4635777A1Measuring an insulation resistance of an on-board electrical system of an electric vehicle
Publication Date: 2025.10.22 AVL DITEST
  • EP4635777A1 patent drawingFigure 1
  • EP4635777A1 patent drawingFigure 2~3
  • EP4635777A1 patent drawingFigure 4~5

AI summary

In order to measure an effective insulation resistance of the electrical insulation of a high-voltage vehicle electrical system (2) of an electric vehicle (1) simply and safely, it is provided that a charging plug (8) of a measuring device (10) is plugged into a charging socket (7) of the electric vehicle (1), then a charging process of the electric vehicle (1) is initialized with the measuring device, and after the charging process has been initialized, the effective insulation resistance (Rw) between at least one charging voltage contact (DC+, DC-) of the charging plug (7) and a reference voltage contact (PE) of the charging plug is measured.