Vehicle Battery Cell Charging with Target Voltage and Capacity Balancing
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Solution Overview
Problem
Charging a vehicle's battery to store sufficient energy for a specified distance is challenging due to variations in cell capacity and voltage limitations, which can result in some cells becoming capacity-limited, preventing the target energy storage.
Innovation Solution
Implementing algorithms and systems that charge each cell to a common target capacity and voltage, adjusting cell voltages and capacities iteratively to ensure the battery pack stores the required energy, and using resistive circuitry for cell balancing during charging.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If all cells are charged to a common target voltage, then charging simplicity is maintained, but some cells become capacity-limited and cannot store sufficient energy
Solution Approach 1:
The patent applies local quality by differentiating charging treatment for different cell groups. Cells are divided into a first group and a second group, where the first group is charged to a first target voltage and the second group is charged to a second target voltage. This localized differentiation allows each group to be charged according to its specific capacity characteristics, preventing capacity-limited cells from restricting overall energy storage while maintaining controlled charging complexity through systematic grouping.
2Quantity of substance
If cells are charged to achieve target energy storage, then energy sufficiency is improved, but cell capacity variations cause some cells to become voltage-limited
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting charging parameters based on cell capacity characteristics. The system determines target voltages for different cell groups based on their specific capacity values. For cells with lower capacity, a lower target voltage is set to prevent them from becoming voltage-limited, while cells with higher capacity can accept higher target voltages. This parameter adaptation ensures all cells contribute to energy storage without being constrained by voltage limits.
3Quantity of substance
If iterative adjustment of cell voltages and capacities is performed, then energy storage optimization is improved, but charging system complexity increases
Solution Approach 1:
The patent applies segmentation by dividing the battery pack's cell population into distinct groups based on capacity characteristics. Cells are classified into a first group and a second group with different target voltages. This segmentation simplifies the control complexity by reducing the problem from individual cell management to group-level management, where each group follows a standardized charging protocol tailored to its capacity range, thereby optimizing energy storage without requiring complex individual cell control.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Ensures that the battery pack stores sufficient energy to support the target drive range by optimizing cell capacities and voltages, while also providing insights into remaining battery life and potential need for replacement.
Implementation Method 1
Some cells of a traction battery may be charged to a specified common target voltage, and other cells of the traction battery may be charged to a predetermined common target capacity
Implementation Method 2
using resistive circuitry for cell balancing during charging
Data Source
AI summary
A vehicle power system includes a battery having a plurality of cells and at least one controller. The at least one controller causes the cells to acquire charge for a period of time such that at the expiration of the period of time, voltages of some of the cells are approximately equal to a specified voltage, amp·hours stored by other of the cells are approximately equal, and an amount of energy stored by the battery is at least equal to a predetermined target energy amount.