Dynamic Battery Current Derating via Discharge Curve Models
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Solution Overview
Problem
Existing battery management systems fail to effectively protect batteries from overdischarge and overcharge by not adequately adjusting charge/discharge currents based on the battery's state of charge and temperature, leading to potential damage due to rapid voltage changes.
Innovation Solution
A battery management apparatus that calculates a current derating ratio using discharge or charge curve models to determine an allowed upper limit of charge/discharge current, incorporating internal resistance and resistance change ratios to adjust current levels based on state of charge and temperature, thereby preventing overdischarge and overcharge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the battery management apparatus uses preset lower limit and upper limit voltage values to prevent overdischarge and overcharge, then the battery protection function is provided, but the rapid voltage changes near these limits cause inaccurate protection timing and potential battery damage
Solution Approach 1:
The patent changes the voltage parameters from fixed preset values to dynamic values that vary with state of charge and temperature. By using derating ratios calculated from discharge curve models, the voltage thresholds adapt to the battery's actual characteristics, resolving the contradiction between providing protection and achieving accurate detection timing.
2Reliability
If the battery management apparatus monitors voltage changes to detect overcharge and overdischarge risks, then the battery protection capability is enhanced, but the system cannot effectively adjust charge/discharge currents based on state of charge and temperature
Solution Approach 1:
The patent implements a feedback mechanism where the battery management apparatus continuously monitors state of charge and temperature, calculates appropriate derating ratios from stored discharge curve models, and adjusts the charge/discharge current limits accordingly. This closed-loop control enables both accurate protection capability and adaptive current adjustment.
Solution Approach 2:
The patent transforms the static current limits into dynamic values that change with battery state. By calculating derating ratios based on real-time state of charge and temperature measurements against pre-stored discharge curve models, the system adapts current limits to match the battery's actual condition, achieving both protection and adaptability.
3Device complexity
If the battery management apparatus uses fixed maximum charge/discharge current values, then the system operation is simplified, but the battery cannot be protected from damage due to rapid voltage changes under varying temperature and state of charge conditions
Solution Approach 1:
The patent applies preliminary action by pre-calculating and storing discharge curve models and derating ratios for various state of charge and temperature conditions. When operation occurs, the system simply looks up the appropriate derating ratio based on current conditions, maintaining operational simplicity while ensuring reliable protection through pre-computed accurate parameters.
Data Source
AI summary
Disclosed is an apparatus and method for managing a battery. The battery management apparatus according to an embodiment of the present disclosure includes a memory unit and a control unit. The memory unit is configured to store a plurality of discharge curve models including a first discharge curve model associated with a first state of charge value, and in this instance, the first discharge curve model defines a change in voltage of a battery having the first state of charge value over time under a first discharge condition. The control unit is connected to the memory unit, allowing communication with the memory unit, and is configured to call the first discharge curve model stored in the memory unit.