Battery Open Cell Voltage Estimation During Load Operation
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Solution Overview
Problem
Existing battery management systems struggle to accurately estimate open cell voltage, state of charge, and state of health while the battery is connected to a load, as direct measurement of open cell voltage is not possible during operation, leading to inaccurate determination of these critical battery characteristics.
Innovation Solution
A method and system that utilize a current sensor, voltage sensor, and controller to estimate open cell voltage, state of charge, and state of health by measuring current and voltage levels, generating an estimated open cell voltage based on a predetermined battery model, and identifying the excitation level using a cost optimization process, allowing for accurate estimation even when the battery is connected to a load.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the battery is disconnected from the load to measure open cell voltage directly, then measurement precision is improved, but productivity is worsened due to operational interruption
Solution Approach 1:
The patent introduces an intermediary estimation system that uses measured current and voltage levels, combined with a predetermined battery model, to calculate open cell voltage without requiring physical disconnection. The controller acts as an intermediary between the sensors and the battery model to derive the voltage estimation mathematically.
Solution Approach 2:
The patent replaces the mechanical/disphysical action of disconnecting the battery from the load with an electrical/mathematical estimation process. Instead of physically separating the circuit to measure voltage, the system uses electrical measurements and computational modeling to determine the equivalent information.
2Productivity
If the battery remains connected to the load for continuous operation, then productivity is improved, but measurement precision of open cell voltage deteriorates
Solution Approach 1:
The system continuously monitors current and voltage levels during battery operation and uses this feedback information to update the open cell voltage estimation in real-time. The controller processes ongoing measurements and adjusts the estimated voltage based on the predetermined battery model, maintaining accuracy throughout continuous operation.
Solution Approach 2:
The patent changes the approach from directly measuring a single voltage parameter to monitoring multiple parameters (current and voltage levels) simultaneously and deriving the open cell voltage through computational relationships. This parameter transformation enables continuous monitoring without operational interruption.
3Productivity
If open cell voltage is estimated using predetermined models during operation, then productivity is improved, but device complexity increases due to additional sensors and processing
Solution Approach 1:
The controller serves multiple functions: it monitors current levels, measures voltage levels, processes data through the predetermined battery model, calculates open cell voltage estimates, and determines state of charge and state of health. This multi-functionality reduces the need for separate dedicated components for each task.
Solution Approach 2:
The battery management system uses the battery's own operational characteristics (current and voltage during normal operation) to generate the estimation data. The system leverages the existing operational parameters rather than requiring external testing equipment or additional specialized sensors.
Data Source
AI summary
A method for monitoring a battery while the battery is connected to a load has been developed. The method includes measuring a first current level flowing through the battery to the load and a first voltage level of the battery at a first time, generating an estimated open cell voltage (OCV) of the battery at the first time based on the first current level, the first voltage level, and a predetermined model of the battery, identifying a first excitation level of the battery at the first time based on the first voltage level, the first current level and a cost optimization process, and identifying at least one of a state of charge (SoC) and state of health (SoH) of the battery using the estimated OCV only in response to the first excitation level being below a predetermined threshold.