EV Battery Leakage Detection Using Negative-Terminal Grounding
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Solution Overview
Problem
Existing methods for detecting electric leakage between a battery and a chassis in electric vehicles are inadequate, as they typically use the chassis as ground, making it difficult to detect leakage when the negative terminal is involved, and fail to identify the specific location of the leakage.
Innovation Solution
An electric leakage detection apparatus and method that uses the negative terminal of the battery as ground, employing a control unit, switches, resistors, and an analog-to-digital converter to determine insulation resistance and diagnose the leakage location by switching between different voltage measurement modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the chassis is used as ground for voltage sampling, then voltage measurement can be performed, but electric leakage involving the negative terminal cannot be detected
Solution Approach 1:
The patent inverts the traditional grounding approach by using the negative terminal of the battery as the ground reference instead of the chassis. This inversion enables the detection of electric leakage between the negative terminal and chassis, which was previously undetectable when using chassis as ground. The voltage sampling is performed between the positive terminal and negative terminal, with the negative terminal serving as the reference potential.
Solution Approach 2:
The patent introduces switching circuits as intermediaries to selectively connect different measurement paths. The switching circuit enables the system to alternate between measuring voltage under normal conditions (positive terminal to chassis) and under leakage conditions (positive terminal to negative terminal), thereby providing versatile detection capability for different leakage scenarios.
2Measurement precision
If traditional voltage sampling method is used, then simple voltage measurement is achieved, but specific leakage location cannot be identified
Solution Approach 1:
The patent segments the battery system into multiple battery packs, each further divided into series-connected battery cells. By measuring voltage across each battery pack and comparing the voltage distribution, the system can identify which specific battery pack or cell is involved in the electric leakage, thereby locating the leakage source without requiring complex additional sensors.
Solution Approach 2:
The control unit continuously monitors voltage values from the ADC and compares them against expected ranges. When abnormal voltage patterns are detected indicating leakage, the system provides feedback by identifying the specific battery pack or cell location, enabling targeted intervention and repair.
3Measurement precision
If multiple switching modes are implemented for comprehensive detection, then leakage detection accuracy is improved, but control circuit complexity increases
Solution Approach 1:
The patent implements periodic switching between different measurement modes under control of a control unit. The system alternates between normal operation mode and leakage detection mode, with switching circuits periodically connecting different voltage sampling paths. This periodic action enables comprehensive leakage detection while keeping the control logic manageable through systematic mode transitions.
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 effective detection of electric leakage between the battery and chassis, including identifying the specific location of the leakage, thereby preventing accidents and ensuring safe operation.
Implementation Method 1
a capacitor connected between a sixth node and a seventh node
Implementation Method 2
a first resistor connected between a fifth node suitable for being connected to a chassis of the electric vehicle and the second node; a second resistor connected between the fourth node and the fifth node
Implementation Method 3
a first switch connected between a first node suitable for being connected to a negative terminal of the battery and a second node; a second switch connected between a third node suitable for being connected to a positive terminal of the battery and a fourth node
Implementation Method 4
an analog-to-digital converter (ADC) configured to generate a digital signal indicating a voltage between the first node and the eighth node
Data Source
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AI summary
An electric leakage detection apparatus for a battery included in an electric vehicle according to the present disclosure transmits a first voltage corresponding to a voltage between a negative terminal of the battery and a chassis of the electric vehicle to an analog-to-digital converter through a capacitor. The electric leakage detection apparatus transmits a second voltage corresponding to a voltage between a positive terminal of the battery and the chassis to the analog-to-digital converter through the capacitor. The analog-to-digital converter outputs digital signals indicating the first voltage and the second voltage using the negative terminal as the ground. The electric leakage detection apparatus determines the first voltage and the second voltage based on the digital signals, and detects an electric leakage between the battery and the chassis based on the first voltage and the second voltage.