Battery Capacity Estimation Using Voltage Inflection Resets
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing methods for estimating residual battery capacity, such as the Coulomb counting and OCV measurement methods, face challenges like accumulated errors and fluctuating calculations, especially in hybrid vehicles and at low temperatures, making it difficult to secure stable precision.
Innovation Solution
An apparatus and method that includes a current monitor, voltage monitor, Coulomb counter, differentiation circuit, and reset detecting circuit to integrate current values, detect differential voltage values, and reset accumulated errors using inflection points, allowing for precise estimation of residual battery capacity without relying on complex OCV measurement tables.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the Coulomb counting method is used to estimate residual battery capacity, then the method is resistant to load fluctuation and obtains a stable residual capacity, but errors are easily accumulated due to current integration
Solution Approach 1:
The patent uses OCV measurements as feedback to detect inflection points in the voltage curve, which trigger reset operations on the Coulomb counter. This feedback mechanism allows the system to maintain the stability benefits of Coulomb counting while periodically correcting accumulated errors through voltage-based detection, thereby resolving the contradiction between stability and precision.
Solution Approach 2:
The patent introduces OCV measurement as an intermediary element that mediates between the Coulomb counting process and the final residual capacity estimation. The OCV measurements provide an independent verification mechanism that detects when accumulated errors have reached a threshold (inflection points), enabling corrective reset operations without disrupting the continuous Coulomb counting process.
2Measurement precision
If the OCV measurement method is used to estimate residual battery capacity, then an accurate value is obtained during normal use, but the calculation value fluctuates when load greatly fluctuates within a short time
Solution Approach 1:
The patent dynamically switches between relying on OCV measurements and Coulomb counting based on detected inflection points. During normal operation, the system uses Coulomb counting for stable continuous estimation, but dynamically activates OCV-based reset operations when inflection points are detected, creating a dynamic hybrid approach that adapts to changing battery states and load conditions.
Solution Approach 2:
The patent changes the operational parameters of the estimation system by introducing inflection point detection based on voltage differential changes. This parameter change allows the system to identify specific states where OCV measurements indicate accumulated errors, triggering parameter resets in the Coulomb counter to maintain accuracy while preserving the stability of continuous counting.
3Adaptability or versatility
If a hybrid scheme combining Coulomb counting and OCV measurement is used, then both methods are utilized, but it is difficult to exclude accumulated error due to current integration and calculation precision is lowered
Solution Approach 1:
The patent implements a feedback-controlled hybrid scheme where OCV measurements continuously monitor the battery state and provide feedback signals when inflection points are detected. This feedback mechanism selectively triggers reset operations only when necessary, avoiding the continuous switching and conflicting calculations of traditional hybrid approaches, thereby maintaining both adaptability and precision.
Solution Approach 2:
The patent uses inflection point detection as an intermediary mechanism that coordinates between Coulomb counting and OCV measurement methods. Rather than simply combining both methods which creates conflict, the inflection point detector acts as a mediator that determines when to switch between or reset the two methods, eliminating accumulated errors while preserving the versatility of the hybrid approach.
Data Source
AI summary
An apparatus for estimating a residual capacity of a storage battery including an electrode whose stage structure is changed based on a state of includes a current monitor configured to monitor a current value flowing in the storage battery; a voltage monitor configured to monitor a voltage value of the storage battery; a Coulomb counter configured to integrate the current value monitored by the current monitor; a differentiation circuit configured to detect a differential value of the voltage value monitored by the voltage monitor; a reset detecting circuit configured to reset an accumulated error due to current integration of the Coulomb counter using an inflection point of the differential value detected by the differentiation circuit; and a residual capacity estimating part configured to estimate a residual capacity of the storage battery based on a value of the Coulomb counter.