Energy Storage Charge Limit Control Across CC-CV Transition
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Solution Overview
Problem
The charge acceptance performance of energy storage devices is not sufficiently utilized when a region for reducing charge current is provided between constant current (CC) and constant voltage (CV) charging, leading to inefficiencies and potential safety issues.
Innovation Solution
A management apparatus that acquires current and voltage values from energy storage devices and calculates a current limit value based on internal resistance, using a current limit characteristic to optimize charge acceptance performance while maintaining safety, by predicting changes in current and voltage values and adjusting the charge current accordingly.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a region for reducing charge current is provided between CC and CV charge, then safety is improved by preventing excessive heat generation and electrodeposition, but charge acceptance performance cannot be sufficiently utilized
Solution Approach 1:
The patent applies dynamics by making the charge current dynamically adjustable based on real-time battery state. Instead of using a fixed reduced current in the transition region, the system continuously calculates the maximum allowable current based on battery temperature, voltage, and charge state, allowing the current to be optimized at each moment rather than constrained by a static limit.
Solution Approach 2:
The patent changes parameters by using multiple variable parameters (temperature, voltage, charge state) to determine the charge current instead of a single fixed parameter. The system calculates the current limit based on combinations of these parameters, allowing flexible adjustment of charge acceptance while maintaining safety margins for heat generation and electrodeposition prevention.
2Object-affected harmful factors
If charge current is reduced in the transition region between CC and CV charge, then heat generation is prevented, but charge efficiency decreases
Solution Approach 1:
The patent implements feedback by continuously monitoring battery temperature, voltage, and charge state, then using this feedback to adjust the charge current in real-time. The system calculates the maximum allowable current based on the current battery state and adjusts the charging profile accordingly, creating a closed-loop control that optimizes charge efficiency while preventing excessive heat generation.
Solution Approach 2:
The patent applies partial action by allowing charge current to be maintained at higher levels when battery conditions permit, rather than uniformly reducing current across all transition regions. The system selectively applies current reduction only when necessary based on real-time conditions, maximizing charge acceptance while maintaining safety margins.
3Reliability
If a fixed current limit is applied in the transition region, then safety is maintained, but charge acceptance performance is not optimized
Solution Approach 1:
The patent applies self-service by enabling the battery management system to autonomously determine the optimal charge current based on the battery's own state parameters. The system uses the battery's temperature, voltage, and charge state to calculate its own maximum allowable current, eliminating the need for external conservative limits and allowing the battery to receive the maximum safe charge at each moment.
Solution Approach 2:
The patent applies preliminary action by pre-calculating safe operating boundaries based on battery characteristics, then using these boundaries to guide real-time current adjustment. The system establishes safety margins for heat generation and electrodeposition in advance, then operates within these margins to maximize charge acceptance during the transition region.
Data Source
AI summary
A management apparatus includes an acquisition unit that acquires a current value and a voltage value of an energy storage device, and a calculation unit that calculates a current limit value along a current limit characteristic of the energy storage device based on internal resistance of the energy storage device and the acquired current value and voltage value.