Battery Management System Optimizing Internal Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery management systems fail to effectively prevent over-discharge due to variations in internal resistance caused by discharging current, even when state of charge and temperature are constant.
Innovation Solution
A battery management system that measures discharging current and uses voltage-current characteristic profiles to determine a reference resistance and an optimum resistance, adjusting output power to prevent over-discharge by calculating these resistances based on specific state of charge, temperature, and discharging current.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If conventional techniques use linearized voltage-current characteristics with data fitting algorithms to calculate internal resistance, then the calculation process is simplified, but the accuracy of internal resistance determination deteriorates because internal resistance changes with discharging current magnitude even when state of charge and temperature are constant
Solution Approach 1:
The patent applies dynamics by transitioning from a static internal resistance model (single value at constant SOC and temperature) to a dynamic model where internal resistance varies with discharging current magnitude. The system continuously adjusts the internal resistance value based on the actual discharging current, enabling accurate over-discharge prevention across different operating conditions.
Solution Approach 2:
The patent changes the parameter of internal resistance from a fixed value to a variable that depends on discharging current magnitude. By establishing a relationship between internal resistance and discharging current (through experiments or lookup tables), the system selects appropriate internal resistance values based on actual operating conditions, thereby improving measurement precision without excessive complexity.
2Device complexity
If the battery management system uses a fixed internal resistance value for over-discharge prevention, then the control logic is simplified, but the reliability of over-discharge prevention deteriorates because internal resistance varies with discharging current
Solution Approach 1:
The system changes the internal resistance parameter from fixed to variable based on discharging current. By pre-establishing the relationship between internal resistance and discharging current through experiments or storing in lookup tables, the control logic remains relatively simple while achieving reliable over-discharge prevention across different current magnitudes.
Solution Approach 2:
The patent applies preliminary action by pre-determining the relationship between internal resistance and discharging current through experiments before actual operation. This pre-characterization allows the system to quickly lookup or calculate appropriate internal resistance values during operation, maintaining simple control logic while ensuring reliable over-discharge prevention.
3Duration of action of stationary object
If the system adjusts output power adaptively to prevent over-discharge, then the battery life is extended, but the device complexity increases due to the need for real-time internal resistance optimization
Solution Approach 1:
The system achieves adaptive output power adjustment by changing the internal resistance parameter based on discharging current. This approach extends battery life through accurate over-discharge prevention while minimizing device complexity by using straightforward current-based resistance selection rather than complex real-time optimization algorithms.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
Provided are a battery management system and method for optimizing an internal resistance of a battery. The battery management system includes: a current measurement unit configured to measure a discharging current of the battery; a memory configured to store a plurality of voltage-current characteristic profiles; and a control unit operatively connected to the current measurement unit and the memory and configured to determine a reference profile from the plurality of voltage-current characteristic profiles based on a state of charge and a temperature of the battery. The reference profile includes a start point, an end point, and a plurality of intermediate points positioned between the start point and the end point. The control unit is further configured to: determine an internal resistance of the battery based on the start point and the end point; set one of the plurality of intermediate points as a reference point; determine a reference resistance smaller than the internal resistance based on the reference point and the end point; and determine an optimum resistance larger than the internal resistance based on the discharging current, the internal resistance, the reference resistance, and a predetermined discharge upper limit current.