Battery Capacity Measurement via Open Circuit Voltage and Accumulation Counter
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Solution Overview
Problem
Current battery capacity measurement methods, such as voltage-based and coulomb counting, face inaccuracies due to battery impedance and accumulated errors, especially under dynamic load conditions, making it challenging to accurately predict remaining battery life without additional circuitry or increased financial cost.
Innovation Solution
A system and method that measures open circuit voltage, uses an accumulation counter to store and adjust battery capacity based on charging or discharging processes, and employs a host device to initialize and calibrate the counter, ensuring accurate remaining capacity calculation through open circuit voltage and other parameter monitoring.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If voltage measurement is used for battery capacity reports, then hardware cost is reduced and the scheme is simple, but measurement precision deteriorates due to battery impedance effect
Solution Approach 1:
The patent introduces an accumulation counter as an intermediary mechanism that stores capacity information. Instead of directly measuring voltage to determine capacity, the system uses voltage to update the accumulation counter which then provides capacity reports. This mediator eliminates the direct impact of battery impedance on capacity measurement while keeping the hardware simple.
Solution Approach 2:
The accumulation counter serves itself by automatically updating based on voltage measurements and providing capacity information without requiring complex external circuitry. The system uses its own voltage measurements to update its internal state, making the measurement process self-sufficient and avoiding additional expensive components.
2Ease of operation
If coulomb counting approach is used with CPU, then remaining capacity can be directly provided to host, but financial cost increases
Solution Approach 1:
The patent extracts the CPU function from the battery monitor and relocates it to the host system. The battery monitor only needs to provide basic voltage measurements and update the accumulation counter, while the host CPU performs the complex calculations and provides capacity reports. This separation removes the need for an expensive CPU in the battery monitor while maintaining direct capacity reporting capability.
3Device complexity
If voltage-based measurement is used to initialize coulomb counting, then the process is simple, but measurement precision deteriorates due to battery impedance
Solution Approach 1:
The patent applies preliminary calibration action to the accumulation counter. Before normal operation begins, the system performs a calibration phase where it compares accumulation counter readings with actual capacity measurements and applies correction factors. This preliminary action eliminates initialization errors caused by voltage-based measurement while keeping the overall system simple.
4Productivity
If dynamic load monitoring is performed with coulomb counting, then battery status tracking is comprehensive, but measurement precision deteriorates due to accumulated error
Solution Approach 1:
The patent implements feedback mechanisms where the system periodically compares accumulation counter readings with actual voltage-based capacity measurements. When discrepancies are detected, the system adjusts the accumulation counter values to correct accumulated errors. This feedback loop maintains long-term accuracy while preserving comprehensive dynamic monitoring capability.
Data Source
AI summary
A method and system for measuring the remaining capacity of a battery with open circuit voltage detection is disclosed. The method includes the steps of measuring an open circuit voltage, obtaining an initial capacity based on the open circuit voltage, initializing an accumulation counter with the initial capacity, adjusting the accumulation counter, and obtaining the remaining capacity based on the accumulation counter. The method further includes the step of calibrating the accumulation counter to eliminate accumulated error and offset resulting from the previous operation of adjusting the accumulation counter.