Capacitor-Based Charging Rate Leveling for Battery Packs
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Solution Overview
Problem
Existing battery management systems require repeated energy transfers to level the charging rates of battery cells, leading to complex operations and prolonged times, especially when many cells are degraded, which complicates the balancing process.
Innovation Solution
A charging rate leveling device that includes a battery cell charger and auxiliary battery charger, connected via selectors and a controller to selectively connect battery cells for charging and discharging, allowing for efficient transfer of energy to reduce charging rate differences among cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If energy is transferred via inductor between battery cells, then voltage of each battery cell is leveled, but the quantity of energy transferable in one operation is small requiring repeated transfers which complicates operation and increases time
Solution Approach 1:
The patent introduces a capacitor as an intermediary energy storage device between the battery cells. The capacitor can store large amounts of energy and release it quickly to balance voltage differences between cells, eliminating the need for repeated small transfers through inductors. This mediator approach resolves the contradiction by enabling effective voltage leveling while reducing operational complexity and time.
2Reliability
If energy is transferred via inductor between battery cells, then voltage of each battery cell is leveled, but repeated transfers are required which increases time consumption
Solution Approach 1:
The capacitor serves as a high-capacity energy buffer that can rapidly charge and discharge to equalize voltage across battery cells in a single or few operations. This intermediary device eliminates the time-consuming repeated transfers required by inductor-based systems, directly addressing the time loss issue while maintaining effective voltage leveling.
3Reliability
If charging rate of degraded battery cells is limited, then other battery cells cannot be fully consumed, but whole capacity of battery module decreases
Solution Approach 1:
The system performs preliminary voltage balancing of individual battery cells before they are connected into the battery module. By pre-leveling the voltage of each cell using the capacitor-based device, the system ensures that all cells start at equal charge levels, eliminating the need to limit charging rates due to degraded cells. This preliminary action restores the full capacity of the battery module while maintaining cell balance.
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
This solution enables quick leveling of charging rates among battery cells by transferring large amounts of energy in fewer operations, reducing the complexity and time required for balancing, and can effectively manage both high and low voltage cells.
Implementation Method 1
a battery cell charger connected to an auxiliary battery separated from the battery pack
Implementation Method 2
a DC-DC converter connected to the auxiliary battery; a converter selector capable of selectively connecting the DC-DC converter to each of the plurality of battery cells
Data Source
AI summary
Provided are a charging rate leveling device and a power supply system including the charging rate leveling device capable of leveling more quickly a charging rate of a plurality of battery cells a battery pack includes. In the power supply system a controlling device includes a two-way DC/DC convertor connected to an auxiliary battery separated from the battery pack, a switch array capable of selectively connecting each of the plurality of auxiliary battery cells the battery pack includes to the two-way DC/DC convertor, so as to charge the battery cell with electric power of the auxiliary battery, and a controller controlling the switch array to connect the lowest voltage battery cell selected among the plurality of battery cells, so as to reduce a difference between charging rates SOC of each of the plurality of battery cells.