Battery ECU SOC-OCV Curve Estimation via Charge Transfer
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Solution Overview
Problem
Existing systems face challenges in accurately estimating the correlation information between the State Of Charge (SOC) and Open-Circuit Voltage (OCV) of electric storage sections, which is crucial for precise SOC grasping, especially when using multiple storage batteries with different characteristics.
Innovation Solution
The system employs a method to determine and estimate the SOC-OCV curve by performing charge/discharge operations between storage batteries, using a battery ECU to select the most probable SOC-OCV curve from pre-stored reference data based on acquired (SOC, OCV) data, and adjusts the charge/discharge amounts to maintain optimal battery usage and minimize degradation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If correlation information between SOC and OCV is preset or estimated based on some parameters, then accuracy for grasping SOC is improved, but the correlation information cannot be efficiently estimated
Solution Approach 1:
The system pre-stores multiple SOC-OCV correlation curves in the storage section, each corresponding to different capacity retention rates. This preliminary preparation allows the ECU to quickly select an appropriate curve without performing time-consuming real-time estimation, thus improving both accuracy and efficiency
Solution Approach 2:
The system changes the parameter used for curve selection from direct real-time estimation to selecting based on capacity retention rate. By estimating the capacity retention rate and selecting the corresponding pre-stored curve, the system achieves accurate SOC estimation without the computational burden of estimating correlation information from scratch
2Measurement precision
If charge/discharge operations are performed between storage batteries, then (SOC, OCV) data is acquired for determining SOC-OCV curve, but battery usage and degradation must be managed
Solution Approach 1:
The system performs charge/discharge operations only to the extent necessary for acquiring (SOC, OCV) data points, rather than performing complete charge/discharge cycles. The ECU controls the charge/discharge amounts to acquire sufficient data while minimizing unnecessary battery stress and degradation
Solution Approach 2:
The ECU continuously monitors the (SOC, OCV) data acquired during charge/discharge operations and uses this feedback to determine the SOC-OCV curve. The system adjusts subsequent charge/discharge operations based on the accumulated data, optimizing the balance between acquiring accurate curve information and managing battery usage
Data Source
AI summary
A power supply apparatus has a first electric storage section, a second electric storage section having an excellent energy density and a poor output density compared with the first storage section, and a control section that acquires first data and second data before and after each time of transferring charge between the first and storage sections, the first data being a combination of an SOC and an OCV of the first storage section, the second data being a combination of an SOC and an OCV of the second storage section, estimates a first correlation between the SOC and the OCV of the first storage section from an aggregation of the first data including reference data, and estimates a second correlation between the SOC and the OCV of the second storage section based on a comparison between a plurality of stored data and an aggregation of the second data.