Battery Pack Protection Circuit for Overcharge Prevention
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Solution Overview
Problem
Battery packs face risks of overcharging and thermal runaway due to malfunctioning switches, leading to potential damage, combustion, or explosion, as existing protection mechanisms may not adequately respond in time.
Innovation Solution
A battery pack design incorporating a battery management unit that monitors voltage, temperature, and current, and operates a balancing unit and protection unit, including a fuse or self-control protector, to block high-current paths and prevent overcharging, while also generating an alarm signal for malfunctioning switches.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a charging switch and discharging switch are used to protect the battery, then the battery can be protected from overcharging and overdischarging, but the switches may malfunction and fail to operate properly, leading to overcharging and thermal runaway
Solution Approach 1:
The protection circuit performs preliminary detection of overcharge conditions and proactively turns off the charging switch before thermal runaway occurs. The circuit monitors battery voltage and current in advance, and executes protective action by opening the charging switch when threshold values are reached, preventing the harmful effect of overcharging and thermal runaway.
Solution Approach 2:
A protection circuit acts as an intermediary between the charging system and the battery. This intermediary circuit includes detection units that monitor battery voltage and current, and control units that manage the charging switch. The protection circuit mediates the charging process by continuously monitoring conditions and intervening to turn off the charging switch when necessary, ensuring reliable protection even if the main charging switch malfunctions.
2Stability of the object's composition
If the balancing unit operates to balance voltages between battery cells, then voltage balance is improved, but the operation time and energy consumption increase
Solution Approach 1:
The balancing unit enables battery cells to self-balance their voltages through controlled self-discharging. Each battery cell that has higher voltage can discharge through its own balancing circuit to match the voltage of other cells. This self-service mechanism achieves voltage balance without requiring continuous external control or energy input, reducing the duration and energy consumption of balancing operations.
Solution Approach 2:
The balancing circuit changes the electrical parameters (voltage and current) of individual battery cells dynamically. By adjusting the discharge current through each cell's balancing resistor based on its voltage state, the system achieves voltage balance across all cells. The parameter changes are automatically adjusted as cells approach equilibrium, naturally reducing the balancing operation time when voltage differences become small.
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 prevents overcharging and thermal runaway by ensuring timely intervention through the balancing and protection units, reducing the risk of damage or explosion and providing timely alerts for user intervention.
Implementation Method 1
The balancing unit may be for balancing a voltage by self-discharging of the battery cells
Implementation Method 2
a protection unit on the high-current path of the battery for blocking the high-current path when the temperature of the battery exceeds a first threshold value
Implementation Method 3
The protection unit may include at least one of a fuse that is blown out when the temperature reaches the first threshold value
Data Source
AI summary
A battery pack and a protection method of the battery pack are provided. The battery pack includes a battery including battery cells, a balancing unit for balancing voltages between the battery cells, a first switch on a high-current path of the battery, and a battery management unit for monitoring a voltage, a temperature, and a current of the battery, for applying a control signal for turning off the first switch, and for operating the balancing unit when the first switch is not turned off in response to the control signal.