Leakage Current Sensing Circuit for High-Voltage Battery Safety
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Solution Overview
Problem
Existing methods fail to accurately and easily sense leakage current in high-voltage batteries used in electric or hybrid vehicles, which can lead to battery discharge, equipment malfunction, and potential safety hazards.
Innovation Solution
A simple leakage current sensing circuit with a voltage distribution node, switches, insulation resistance, current sensing resistance, and a DC voltage applying unit, along with a leakage current determining unit that uses switches, voltage amplifiers, A/D converters, and a CPU to detect and warn for leakage current, setting standard levels for current thresholds.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a leakage current sensing circuit is installed to detect insulation faults in high-voltage batteries, then safety and reliability are improved, but device complexity increases
Solution Approach 1:
The sensing circuit is divided into multiple functional modules: voltage distribution node, insulation resistance element, current sensing resistance element, DC voltage applying unit, and determining unit. Each module performs a specific function, making the overall system manageable despite its complexity while ensuring comprehensive leakage current detection
Solution Approach 2:
An intermediary sensing circuit is introduced between the high-voltage battery system and the ground, using insulation resistance and current sensing resistance elements to indirectly detect leakage current without directly exposing the detection system to high voltage, thus improving safety while maintaining detection capability
2Measurement precision
If existing leakage detection methods are used, then device structure is simple, but measurement precision of leakage current is insufficient
Solution Approach 1:
The patent replaces simple resistive sensing with a more sophisticated electrical sensing mechanism using Ohm's law. By applying controlled DC voltage and measuring the resulting current through high-precision resistance elements, the system achieves accurate leakage current measurement while maintaining relatively simple circuit implementation
Solution Approach 2:
The system changes the operating parameters by applying different DC voltages (positive and negative) to the ground-side end of the current sensing resistance. This allows the determination of leakage current magnitude by comparing current flow under different voltage conditions, significantly improving measurement precision beyond simple continuous monitoring
3Power
If high-voltage battery systems are used in electric vehicles, then power output is improved, but harmful factors such as leakage current shock risk increase
Solution Approach 1:
The sensing circuit performs preliminary detection of insulation faults and leakage current before they can develop into dangerous conditions. By continuously monitoring the electrical state and comparing it against predetermined thresholds, the system identifies potential hazards early, allowing preventive action before shock risk materializes
Solution Approach 2:
The system establishes a feedback loop where the determining unit continuously monitors current through the sensing resistance, compares it with standard levels, and can trigger warnings or protective actions when leakage exceeds thresholds. This closed-loop feedback mechanism dynamically responds to changing conditions, maintaining safety in high-voltage environments
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 early detection of leakage current, preventing battery discharge and equipment malfunction, while ensuring user safety by effectively identifying and warning against hazardous conditions.
Implementation Method 1
a DC (Direct Current) voltage applying unit for selectively applying positive or negative DC voltage to a ground-side end of the current sensing resistance to induce a potential difference between the voltage distribution node and the DC voltage applying node
Implementation Method 2
a leakage current determining unit for sensing a magnitude of an electric current flowing through the current sensing resistance according to the induced potential difference
Data Source
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AI summary
An apparatus for sensing leakage current of a battery includes a voltage distribution node installed on a first conductive line connecting both terminals of a battery; first and second switches installed between the voltage distribution node and positive/negative terminals of the battery; an insulation resistance and a current sensing resistance installed on a second conductive line connecting the voltage distribution node to a ground; a DC voltage applying unit for applying positive/negative DC voltage to a ground-side end of the current sensing resistance to induce potential difference between the voltage distribution node and the DC voltage applying node; and a leakage current determining unit for sensing magnitude of electric current flowing through the current sensing resistance according to the induced potential difference in turning-on state of the switches, and then determining leakage current by checking whether the magnitude of electric current is out of standard level over threshold value.