Parallel Battery Pack Balancing to Limit In-Rush Current
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Solution Overview
Problem
Conventional balancing strategies for battery packs connected in parallel fail to address pack voltage deviations, leading to increased in-rush currents that damage electrical components and battery cells.
Innovation Solution
An apparatus and method for balancing both battery packs and cells within each pack, using a voltage measuring unit, discharge circuits, and a control unit to manage pack and cell voltage deviations, with threshold-based operations to reduce voltage differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If only battery cells within each battery pack are balanced, then cell voltage deviation is reduced, but pack voltage deviation increases leading to more serious in-rush current problems
Solution Approach 1:
The patent divides the balancing control into two distinct levels: cell-level balancing (within each battery pack) and pack-level balancing (across multiple battery packs). The control unit separately manages cell voltage deviations using first threshold values and pack voltage deviations using second threshold values, allowing independent optimization of each balancing level to prevent both cell imbalance and in-rush current issues.
Solution Approach 2:
The control unit acts as an intermediary that coordinates between cell-level and pack-level balancing operations. It monitors both cell voltages and pack voltages, and selectively activates appropriate balancing strategies (cell balancing, pack balancing, or both simultaneously) based on the current voltage deviation states, thereby resolving the conflict between cell balance and in-rush current prevention.
2Quantity of substance
If battery packs are connected in parallel to secure high energy capacity, then energy capacity increases, but pack voltage deviation occurs leading to in-rush current that damages electrical components and battery cells
Solution Approach 1:
The system performs preliminary pack voltage balancing before charging or discharging operations begin. The control unit continuously monitors pack voltages and pre-balances the battery packs by controlling current distribution, ensuring that pack voltage deviations are minimized before high-current charging/discharging starts, thereby preventing in-rush current damage while maintaining high energy capacity.
Solution Approach 2:
The patent implements a feedback control mechanism where the control unit continuously measures pack voltages and cell voltages, compares them against threshold values, and dynamically adjusts current distribution among battery packs and cells. This closed-loop feedback system ensures that voltage deviations are detected and corrected in real-time, preventing in-rush current damage while maintaining the high energy capacity provided by parallel-connected battery packs.
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
Prevents damage to electrical components and battery cells by maintaining pack and cell voltage deviations within threshold limits, thereby reducing in-rush currents.
Implementation Method 1
a voltage measuring unit for measuring voltages of all battery cells included in each battery pack
Implementation Method 2
a discharge circuit for discharging a battery cell having a higher voltage than a pack balancing target voltage
Data Source
Figure 1
Figure 2
Figure 3~4'
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. In addition, 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.