Starting Battery Voltage Recognition Without Current Sensor
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Solution Overview
Problem
The existing battery management systems (BMS) for starting batteries in electric vehicles require current sensors to prevent overcharging, which increases costs and affects price competitiveness.
Innovation Solution
A driving system for starting batteries that includes voltage measurement units, overvoltage determination units, charging FETs, current limiting units, and system off determination units, allowing for the recognition of an off state in an external system without a current sensor by measuring voltage differences across parallel paths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a current sensor is provided to the BMS to prevent overcharging, then the reliability of battery protection is improved, but the cost increases and price competitiveness deteriorates
Solution Approach 1:
The patent extracts the current sensing function from a dedicated current sensor and relocates it to the existing voltage measurement unit. By measuring voltage at different ground positions and calculating current through voltage difference, the system eliminates the need for a separate current sensor while maintaining overcharge protection capability
Solution Approach 2:
The voltage measurement unit is given a dual function: it continues to measure battery voltage for state-of-charge determination and simultaneously performs current sensing by measuring voltage differences between different ground points. This multi-functional approach eliminates the need for additional dedicated current sensing hardware
2Measurement precision
If a current sensor is installed in the BMS to accurately recognize charging state, then the measurement precision of current is improved, but the device complexity and cost increase
Solution Approach 1:
The patent replaces the physical current sensor (electrical measurement device) with a voltage-based measurement approach. By measuring voltage drop across known resistance paths and using Ohm's law calculations, the system achieves current measurement functionality without the physical current sensing hardware
Solution Approach 2:
The patent introduces voltage difference measurement as an intermediary method to indirectly determine current flow. Instead of directly measuring current, the system measures voltage at different ground positions and uses the voltage difference as a mediator to calculate current through the battery management system
3Ease of operation
If the BMS uses voltage measurement to determine system state, then the ease of operation is improved, but the measurement precision of current state deteriorates
Solution Approach 1:
The patent segments the ground reference points into multiple positions (first ground position and second ground position) and measures voltage at each position separately. By comparing these segmented voltage measurements, the system can determine current flow state while maintaining simple voltage-based measurement operations
Data Source
AI summary
The present invention relates to a voltage recognition system of a starting battery and a method of recognizing an off state of an external system using the same, and more particularly, to a driving system of a starting battery and a method of recognizing an off state of an external system using the same, which make it possible to start an engine next time by recognizing the off state of the external system in an overvoltage state according to whether there occurs a difference between values of voltages measured by two ADCs having different positions of ground GND without requiring a current sensor.