Battery Control Device Managing Internal Resistance Deterioration
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Solution Overview
Problem
Existing methods for controlling secondary batteries do not effectively manage the increase in internal resistance, which leads to deterioration in characteristics, and there is a lack of methods to control this increase specifically.
Innovation Solution
A battery control device that includes a storage unit for resistance increase rate data of positive and negative electrodes and a correlation calculation unit to calculate correlations between the battery's state-of-charge, temperature, and current limits, allowing for precise control of the secondary battery's current based on these correlations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If the charge/discharge amount of the secondary battery is increased to enhance energy efficiency, then the instantaneous energy efficiency of the system is improved, but the internal resistance of the secondary battery increases and characteristics deteriorate
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the charge/discharge current limits based on the calculated resistance increase rates of the positive and negative electrodes. The control device modifies operating parameters (current limits) according to the deterioration state of each electrode, allowing the system to optimize energy efficiency while preventing excessive internal resistance increase. This is achieved by calculating resistance increase rates from charging/discharging curves and using these rates to determine appropriate current limits.
2Reliability
If the voltage of the secondary battery is maintained within a range to suppress deterioration, then the battery characteristics are preserved, but the energy efficiency over the whole use period may be reduced
Solution Approach 1:
The patent implements dynamics by transitioning from static voltage-based control to dynamic current-based control that adapts to the battery's deterioration state. The control device continuously calculates resistance increase rates from charging/discharging curves and adjusts current limits in real-time based on these calculations. This dynamic approach allows the system to optimize energy efficiency at each operating point while ensuring that the cumulative resistance increase remains within acceptable limits over the battery's lifetime.
Solution Approach 2:
The patent applies feedback by using the calculated resistance increase rates as feedback signals to adjust charge/discharge current limits. The control device measures charging/discharging curves, calculates resistance increase rates from these curves, and uses these rates as feedback to determine appropriate current limits for subsequent operations. This closed-loop feedback mechanism enables the system to maintain optimal energy efficiency while preventing excessive deterioration.
3Measurement precision
If existing state determination methods based on capacitance are used, then the state of the secondary battery can be determined, but the internal resistance increase cannot be effectively controlled
Solution Approach 1:
The patent applies segmentation by dividing the battery analysis into separate positive electrode and negative electrode evaluations. Instead of treating the battery as a single unit, the control device separately calculates resistance increase rates for each electrode based on their respective charging/discharging curves. This segmentation allows for more precise control, as the current limits can be adjusted based on which electrode is deteriorating faster, enabling effective internal resistance control that capacitance-based methods cannot achieve.
Data Source
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AI summary
Provided is a battery control device capable of controlling the deterioration speed of the characteristics of a secondary battery on the basis of the internal resistances of the positive electrode and the negative electrode of the secondary battery. The battery control device 138 comprises: a storage unit 1381 for holding beforehand a data table DT2 indicating the rate of increase in the resistance of the positive electrode in the secondary battery and a data table DT2 representing the rate of increase in the resistance of the negative electrode in the secondary battery; and a DT1 calculation unit 1382 calculating a data table DT1 representing the correlations among the temperature, the battery state-of-charge and the upper limit current of the secondary battery, and the correlations among the temperature, the battery state-of-charge and the lower limit current of the secondary battery on the basis of the data table DT2, a positive electrode state-of-charge, a negative electrode state-of-charge, a battery state-of-charge, and an allowed range for the rate of increase in the battery resistance of the secondary battery. The battery control device 138 controls the current of the secondary battery on the basis of the data table DT1 calculated by the DT1 calculation unit 1382.