Battery Pack Circulating Current Control via Cell Configuration
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In battery packs with multiple batteries connected in parallel, circulating currents can exceed allowable values due to configuration-specific issues, posing a challenge in maintaining efficient energy transfer and preventing damage.
Innovation Solution
The method involves configuring each battery with a specific number of cells connected in series and parallel, using relays and a booster circuit to manage power flow, and calculating current values based on internal resistances, electromotive voltages, and SOC to prevent excessive circulating currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple assembled batteries are connected in parallel to increase power output, then the power capacity of the battery pack is improved, but circulating current may exceed allowable values causing safety issues
Solution Approach 1:
The patent applies preliminary action by calculating the internal resistance of each assembled battery before parallel connection and pre-determining the number of cells to connect in parallel. This advance calculation and configuration prevents circulating current from exceeding allowable values when batteries are connected in parallel, ensuring safety while achieving the desired power output.
2Adaptability or versatility
If batteries with different characteristics are connected in parallel to increase adaptability, then the versatility of the battery pack is improved, but circulating current distribution becomes unpredictable
Solution Approach 1:
The patent applies local quality by individually calculating and considering the internal resistance characteristics of each assembled battery. Instead of treating all batteries uniformly, the method determines the optimal number of cells to connect in parallel for each specific battery based on its unique internal resistance, thereby managing circulating current while maintaining configuration flexibility.
3Productivity
If the number of cells in parallel is increased to reduce internal resistance, then the current delivery capability is improved, but the complexity of battery configuration increases
Solution Approach 1:
The patent applies parameter changes by dynamically determining the number of cells to connect in parallel based on the internal resistance parameter of each assembled battery. This approach optimizes current delivery capability by adjusting the parallel configuration according to measured internal resistance values, achieving high productivity while managing configuration complexity through systematic parameter-based decision making.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
[PROBLEM] In connecting a plurality of assembled batteries in parallel, to prevent a circulating current from exceeding an allowable current for the assembled battery. [SOLVING MEANS] A battery pack (100) has a plurality of assembled batteries (10-1 to 10-X) connected in parallel. Each of the assembled batteries has a plurality of cells (11) connected electrically. A circulating current in each of the assembled batteries is calculated from an open circuit voltage of the assembled battery that varies according to the number (N1 to Nx) of the cells connected in series, a value indicating a charge state of the assembled battery that varies according to the number (M1 to Mx) of the cells connected in parallel, and an internal resistance of the assembled battery. The number of the cells connected in parallel and the number of the cells connected in series in each of the assembled batteries are numbers determined under the condition that the circulating current should not exceed an allowable current value for the assembled battery.