Parallel Battery Pack Balancing to Prevent In-Rush Current
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Solution Overview
Problem
In battery systems with multiple packs connected in parallel, voltage deviations between battery cells lead to in-rush currents, damaging electrical components and battery cells, as conventional balancing strategies only address cell-level imbalances, neglecting the need for pack-level balancing.
Innovation Solution
An apparatus and method that measure voltages across battery packs, determine pack and cell voltage deviations, and use discharge circuits to balance both pack and cell voltages, reducing deviations to predetermined threshold values, and adjust these values based on charging/discharging cycles and in-rush current levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If only cell-level balancing is performed in battery packs connected in parallel, then cell voltage deviation is reduced, but pack voltage deviation increases leading to in-rush current
Solution Approach 1:
The patent divides the balancing control into two hierarchical levels: cell-level balancing (within each pack) and pack-level balancing (across multiple packs). The processor separately manages cell voltage deviations using first threshold values and pack voltage deviations using second threshold values, preventing in-rush current by coordinating both levels of control.
Solution Approach 2:
The patent extends the balancing control from a single dimension (cell level within packs) to a dual-dimensional approach by adding pack-level voltage monitoring and control. This dimensional expansion allows simultaneous management of intra-pack cell balance and inter-pack voltage equality, solving the in-rush current problem.
2Reliability
If pack-level balancing is added to cell-level balancing, then in-rush current is prevented, but system complexity increases
Solution Approach 1:
The processor performs multiple balancing functions using a unified control architecture. It simultaneously executes cell-level balancing (comparing cell voltages to first threshold values) and pack-level balancing (comparing pack voltages to second threshold values), eliminating the need for separate control systems and reducing overall complexity.
Solution Approach 2:
The patent merges cell-level and pack-level balancing controls into a single integrated system managed by one processor. The processor combines voltage measurement, threshold comparison, and discharge control functions for both cell and pack levels, simplifying the system architecture while maintaining comprehensive balancing capability.
3Manufacturing precision
If discharge circuits are used for balancing, then voltage deviation is corrected, but energy loss increases
Solution Approach 1:
The patent dynamically adjusts discharge control parameters (threshold values, discharge timing, and discharge current) to optimize the balancing process. By changing these parameters based on real-time voltage measurements and deviation magnitudes, the system achieves accurate voltage balance while minimizing unnecessary discharge operations and associated energy losses.
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 approach effectively minimizes voltage differences between battery packs, preventing damage from in-rush currents and maintaining optimal pack and cell balancing, thereby extending the lifespan of battery systems.
Implementation Method 1
a voltage measurer configured to measure voltages of the plurality of battery cells included in each battery pack
Implementation Method 2
a plurality of discharge circuits connected in parallel to correspond to the plurality of battery cells
Data Source
AI summary
Disclosed is an apparatus and method for balancing battery packs connected in parallel. If the pack voltage deviation of the first to nth battery packs is greater than the first threshold value, a battery cell having a higher voltage than the pack balancing target voltage set according to a preset criterion among the voltages of all cells is discharged to perform pack balancing for each battery pack and if the pack voltage deviation is equal to or smaller than the first threshold value, a battery cell having a higher voltage than the cell balancing target voltage set according to a preset criterion among the voltages of the cells included in a battery pack having a cell voltage deviation greater than the second threshold value is discharged to perform cell balancing for each battery pack.