Lithium-ion Battery Voltage Balancing via Synchronized Cell Readings
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery balancing systems face inaccuracies due to voltage reading time differences, leading to incorrect cell balancing and increased complexity, heat generation, and capacity loss in multicell battery packs.
Innovation Solution
A battery balancing system with a system controller that synchronizes voltage readings across all cells in a lithium ion multicell battery pack using synchronization signals and a DC-DC converter to adjust voltage balance, ensuring all cells are read at the same timing and maintaining accurate balancing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If voltage readings are taken sequentially through a line selecting device, then the system can read voltages of multiple cells, but voltage reading errors occur due to timing differences causing incorrect balancing decisions
Solution Approach 1:
The patent applies preliminary action by pre-charging all cell voltages to a reference voltage level before reading. This ensures that all cells are in a stable, known state before the actual voltage measurement begins, eliminating timing-related errors. The system charges all cells to the reference voltage in advance, then reads their voltages simultaneously or in a controlled sequence, ensuring accuracy while maintaining efficiency.
Solution Approach 2:
The patent merges the voltage reading operation with the balancing operation by using the same DC-DC converter and control circuitry for both functions. Instead of having separate reading and balancing systems, the invention combines them into a unified system where the balancing process itself provides the reference voltage level for accurate reading, eliminating the need for separate measurement equipment and reducing timing errors.
2Reliability
If resistance-based discharge method is used for high voltage cells, then cell balancing is achieved, but discharge current increases and heat generation becomes excessive
Solution Approach 1:
The patent replaces the passive resistance-based discharge method with an active DC-DC converter system. Instead of using resistors to dissipate excess voltage as heat, the invention uses a DC-DC converter to actively regulate and transfer energy from high voltage cells to low voltage cells or to a buffer capacitor. This substitution eliminates the need for high power dissipation resistors and significantly reduces heat generation while maintaining effective cell balancing.
3Loss of energy
If DC-DC converter is used to charge low voltage cells, then efficiency is high and heat is reduced, but cell voltage of the entire battery pack becomes lower than its original lowest voltage
Solution Approach 1:
The patent applies preliminary action by first charging all cells to a common reference voltage level before initiating the DC-DC converter-based balancing process. This ensures that the battery pack starts from a stable voltage state, and the subsequent energy transfer operations maintain the overall voltage stability of the pack. The reference voltage serves as a baseline that prevents the pack voltage from dropping below acceptable levels during balancing operations.
Data Source
AI summary
Disclosed are system and method for adjusting a voltage balancing of cell in a lithium ion multicell battery pack, the system comprising; a multicell battery pack including a master module and a slave module, a CPU located in the system controller and outputting a synchronization signal for each of the cells in the master module and the slave module, a first vertical interface transmitting the synchronization signal outputted from the CPU to the master module, and a second vertical interface transmitting the synchronization signal to the slave module through the first vertical interface.