Battery Pack Balancing Circuit for Reverse Voltage Protection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing battery packs are vulnerable to damage from reverse voltages exceeding the withstand voltage of cell fuses, which can lead to arcs and potential ignition or explosion of battery cells.
Innovation Solution
A battery pack design that includes balancing resistors and switches, a rack fuse, a current sensor, and a controller to detect short-circuits and manage balancing operations, thereby reducing the risk of reverse voltage damage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a cell fuse is installed to protect the battery cell from overcurrent, then the battery cell is protected from overcurrent damage, but a reverse voltage exceeding the withstand voltage may be applied to the battery cell when the cell fuse blows, causing electric arcs and potential ignition
Solution Approach 1:
A balancing resistor is introduced as an intermediary component connected in parallel with the battery cell through a balancing switch. When a cell fuse blows and reverse voltage occurs, the balancing switch turns on to provide an alternative current path through the balancing resistor, preventing direct arcing across the cell terminals and dissipating the reverse voltage safely.
Solution Approach 2:
The balancing resistor and switch are pre-configured in the circuit as a protective mechanism. Before reverse voltage damage can occur, the system has the balancing circuit ready to activate. When reverse voltage is detected (through current sensor detection of abnormal current flow), the balancing switch automatically turns on to cushion the impact by diverting the harmful reverse voltage through the resistor.
2Object-affected harmful factors
If balancing switches are turned on to divert reverse voltage through balancing resistors, then the battery cell is protected from reverse voltage damage, but additional components and control logic are required
Solution Approach 1:
The balancing circuit components (balancing resistors and switches) serve dual functions: they provide reverse voltage protection when cell fuses blow, and they perform normal cell balancing operations during regular battery management. This multi-functionality reduces the need for separate dedicated protection components, thereby limiting the increase in device complexity.
Solution Approach 2:
The balancing circuit automatically activates when reverse voltage conditions are detected through current sensor monitoring. The system self-manages the protection function without requiring external intervention or complex control logic - the balancing switch turns on automatically based on predefined current thresholds, and the controller simply monitors and responds to the circuit's self-reported status.
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
The solution effectively protects battery cells from reverse voltage damage by turning on balancing switches to divert reverse voltage through balancing resistors, reducing the risk of arcs and cell damage.
Implementation Method 1
balancing resistors respectively connected to the battery cells... turning on all of the balancing switches to form closed circuits... divert reverse voltage through balancing resistors
Implementation Method 2
a current sensor between the battery cells and the first pack terminal, or between the battery cells and the second pack terminal, and a controller configured to detect pack current between the first pack terminal and the second pack terminal through the current sensor
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A battery pack includes battery cells between first and second pack terminals, balancing resistors respectively connected to the battery cells, balancing switches respectively connected to the battery cells and to the balancing resistors, and configured to form a closed circuit by connecting a corresponding one of the battery cells to a corresponding one of the balancing resistors, a rack fuse between the battery cells and the first pack terminal, or between the battery cells and the second pack terminal, a current sensor between the battery cells and the first pack terminal or the second pack terminal, and a controller configured to detect pack current between the first and second pack terminals through the current sensor, to control the balancing switches, and to detect a short-circuit between the first and second pack terminals based on the pack current and turn on all of the balancing switches.