Battery Management System SOH Estimation via Charge Ratio
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Solution Overview
Problem
Current battery management systems (BMS) for electric and hybrid vehicles face challenges in accurately measuring the state of health (SOH) of battery cells, especially under restricted conditions, which affects the overall performance and longevity of the vehicle's battery.
Innovation Solution
A BMS with a reference setup unit, charge amount calculation unit, and SOH calculation unit that sets a charge termination value, calculates the actual charge amount, and estimates the SOH based on a ratio between the actual and expected charge amounts, allowing for efficient management of battery charge and discharge states, and communication of battery status to the controller.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the BMS calculates SOH under restricted conditions with limited measurements, then the measurement precision is improved, but the reliability of SOH estimation deteriorates
Solution Approach 1:
The system performs preliminary actions by setting a charge termination value before charging begins, and calculates the expected charge amount in advance based on battery capacity and charge rate. This allows the actual charge amount to be compared against a pre-established baseline, enabling accurate SOH estimation even under restricted charging conditions where full charging cycles cannot be performed.
2Measurement precision
If the BMS monitors each battery cell individually, then the measurement precision of charge state is improved, but the device complexity increases
Solution Approach 1:
The patent merges the monitoring of multiple battery cells by calculating the total charge amount based on the sum of individual cell charge amounts. Instead of independently tracking and managing each cell's charge state separately, the system combines them into a unified charge amount calculation, thereby reducing computational complexity while maintaining precise monitoring of each cell's contribution to the overall charge state.
Data Source
AI summary
A battery management system (BMS) and a method of controlling the same are disclosed. In one embodiment, the BMS includes a reference setup unit configured to set a charge completion value used to calculate a state of health (SOH) of the battery, wherein the battery comprises one or more battery packs each including a plurality of battery cells, and a charge amount calculation unit configured to calculate an amount actually charged in the battery from a first point in time when charging of the battery begins to a second point in time when the battery charging actually reaches the charge completion value. The BMS may further include an SOH calculation unit configured to calculate the SOH of the battery based on a ratio of i) the actual charge amount to ii) a preset charge amount expected to be charged from the first time point to the second time point.