Battery Cell Balancing via Parallel Resistor Dissipation
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Solution Overview
Problem
Series-connected battery cells in UPS systems often experience voltage imbalances due to repeated draining and recharging, leading to premature degradation, safety hazards, and reduced battery capacity, as existing charging systems fail to maintain balanced charging effectively.
Innovation Solution
A system that includes resistors selectively coupled in parallel with battery cells via switches, controlled by a unit that determines the lowest voltage cell and adjusts switch activation based on voltage differences to achieve balanced charging, using a delta value threshold that can be dynamically adjusted during the charging process.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If series-connected battery cells are repeatedly drained and recharged, then the battery provides continuous power supply capability, but voltage imbalance develops among cells leading to premature degradation
Solution Approach 1:
The patent applies local quality by implementing individual balancing circuits for each battery cell. Each cell has its own resistor and switch that can be independently activated to dissipate excess charge locally, ensuring that each cell maintains its proper voltage level regardless of variations in other cells during charge/discharge cycles.
Solution Approach 2:
The control unit continuously monitors the voltage of each battery cell and provides feedback control. Based on the measured voltage differences, the control unit selectively activates or deactivates the switches in the balancing circuits, creating a closed-loop system that maintains voltage balance across all cells during operation.
2Productivity
If traditional charging systems are used without cell balancing, then the charging process is simple and fast, but overcharging occurs leading to safety hazards and reduced battery capacity
Solution Approach 1:
The patent implements preliminary action by proactively balancing cell voltages during the charging process before overcharging conditions develop. The control unit continuously monitors cell voltages and activates balancing circuits on cells that are approaching overcharge conditions, preventing safety hazards before they occur rather than reacting after problems arise.
Solution Approach 2:
The balancing system applies local quality control by treating each battery cell individually with its own balancing circuit. This allows the system to apply charge current or dissipation resistance specifically to cells that need it, rather than uniformly treating all cells, thereby preventing overcharging of individual cells while maintaining overall charging efficiency.
3Reliability
If voltage balancing is implemented through selective resistor coupling, then balanced charging is achieved, but device complexity increases due to additional switches and control mechanisms
Solution Approach 1:
The patent applies segmentation by dividing the battery system into independent cell modules, each with its own balancing circuit consisting of a resistor and switch. This modular approach allows the complex balancing function to be distributed across multiple simple, identical units, making the overall system more manageable and easier to control than a centralized complex circuit.
Solution Approach 2:
The control unit simplifies the control logic by using parameter changes - specifically, it monitors voltage differences and uses predetermined threshold values to determine when to activate or deactivate switches. This parameter-based control approach converts a potentially complex continuous control problem into a series of simple binary decisions based on voltage threshold comparisons.
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 ensures balanced charging, reduces the risk of overcharging, prolongs battery life, and decreases charging time by continuously monitoring and adjusting the charge current to each cell, thereby preventing premature degradation and safety hazards.
Implementation Method 1
resistors that are selectably electrically coupled in parallel with respective battery cells
Data Source
Figure 1A~1B
Figure 2A~2B
Figure 3
AI summary
Without battery cell balancing, voltages of multiple series-connected battery cells may quickly become out of balance, which causes some cells of the battery to deteriorate faster than others, and reduces the life cycle of the battery. Embodiments of the present invention address this problem by providing a system for balanced charging of multiple series-connected battery cells. The system includes resistors that are selectably and electrically coupled in parallel with respective battery cells via activation and deactivation of respective switches. The system also includes a control unit that is configured to determine a battery cell having a lowest voltage among the battery cells, and to activate and deactivate the switches as a function of differences in voltages between the voltage of the lowest battery cell and voltages of each of the other battery cells, thus, providing balanced charging of the multiple series-connected battery cells.