Battery Controller Charge Current Adaptation
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Solution Overview
Problem
The charge current limits for rechargeable energy storage systems are overly restrictive due to polarization, necessitating a worst-case assumption of 0% state-of-charge for charging, which is inefficient and does not account for varying initial states-of-charge values.
Innovation Solution
A battery system with a controller that stores multiple charging tables corresponding to different initial state-of-charge values, allowing for the selection and interpolation of charge current limits based on the starting state-of-charge, thereby optimizing charging currents for rapid charging modes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a worst-case assumption of 0% state-of-charge is used to determine charge current limits, then lithium plating is avoided (reliability improved), but charging efficiency deteriorates due to overly restrictive current limits
Solution Approach 1:
The patent changes the parameter of state-of-charge assumption from a fixed worst-case value (0%) to a variable value that reflects the actual initial state-of-charge. By adjusting this parameter based on measured or estimated actual SOC, the system optimizes charge current limits to prevent lithium plating while maximizing charging efficiency.
Solution Approach 2:
The patent transitions from a static charge current limit approach (based on fixed 0% SOC assumption) to a dynamic approach where current limits are continuously adjusted based on the actual initial state-of-charge. This dynamic adaptation allows the system to respond to varying battery conditions and optimize charging performance in real-time.
2Productivity
If multiple charging tables are stored and selected based on initial state-of-charge, then charging efficiency is improved, but device complexity increases
Solution Approach 1:
The patent segments the charge current limit data into multiple discrete charging tables, each corresponding to a specific initial state-of-charge range. This segmentation allows the controller to efficiently store and quickly retrieve appropriate current limits without processing complex continuous calculations, thereby improving charging efficiency while managing controller complexity through structured data organization.
Data Source
AI summary
A battery system includes a rechargeable energy storage system and a battery controller. The rechargeable energy storage system has a rapid charging mode and a discharging mode. The battery controller is electrically coupled to the rechargeable energy storage system and is configured to store multiple charging tables that contain multiple charge current limit entries, where each charging table corresponds to a unique one of multiple initial state-of-charge values, determine a starting state-of-charge value of the rechargeable energy storage system in response to entering the rapid charging mode, select up to two charging tables in response to the starting state-of-charge value of the rechargeable energy storage system being adjacent to up to two of the initial state-of-charge values, and control a charging current provided to the rechargeable energy storage system based on the charge current limit entries in the up to two charging tables as selected.