Dual Sensor Current Detection for EV Battery SOC Accuracy
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Solution Overview
Problem
Current detection systems for power battery packs in electric vehicles face reliability issues due to failures in shunt-type current sensors, which affect the accuracy of State of Charge (SOC) calculations and mileage and service life of the vehicle.
Innovation Solution
A current detection device incorporating both shunt-type and open-loop Hall-type current measurement units, with a modular design and CAN communication, allows for independent operation and fault diagnosis, ensuring accurate current measurement and enhanced reliability by switching to the Hall-type unit when the shunt-type fails.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a shunt-type current sensor is used to detect current, then the current detection precision is improved, but the reliability deteriorates due to sensor failures
Solution Approach 1:
The patent changes the detection parameter from direct voltage measurement (prone to noise and drift) to frequency measurement (highly stable) by converting the voltage signal through a capacitor and measuring the oscillation frequency of the resulting RC circuit, thereby improving both precision and reliability
Solution Approach 2:
The patent replaces the traditional shunt-type current sensor (electrical measurement system) with a frequency-based detection system using capacitors and oscillation circuits, substituting direct electrical measurement with a more reliable frequency measurement approach that is less susceptible to environmental factors and component aging
2Loss of information
If a shunt-type current sensor is used, then the current value can be acquired, but the fault diagnosis capability deteriorates when the sensor fails
Solution Approach 1:
The patent implements feedback by continuously monitoring the oscillation frequency and comparing it with expected values, allowing the system to detect abnormalities and diagnose faults in real-time, providing both current information and health status of the detection system
Solution Approach 2:
The detection system performs self-diagnosis by monitoring its own operating parameters (oscillation frequency, signal amplitude) and automatically identifying faults without requiring external diagnostic equipment, enabling the system to detect and report its own failures
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
The solution provides precise and reliable current detection, improving the accuracy of SOC calculations and extending the service life of electric vehicle batteries by enabling fault diagnosis and temporary measurement by the Hall-type unit when the shunt-type fails.
Implementation Method 1
a current sensing device having a shunt resistor, configured to acquire a voltage signal of a power battery pack
Implementation Method 2
a temperature acquisition unit that includes a thermistor; the temperature acquisition unit is configured to acquire a resistance value of the thermistor; the sampling and signal processing device is further configured to obtain a detected temperature value of the current sensing device having the shunt resistor according to the resistance value of the thermistor
Data Source
AI summary
The present disclosure provides a current detection system, method and device. The current detection system includes a management unit and a current detection device that is connected with the management unit. The current detection device includes a shunt-type current measurement unit, an open-loop Hall-type current measurement unit and an isolation power unit.