Battery Cell Balancing Using Pulse Discharge to Suppress Dendrites
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Solution Overview
Problem
Lithium ion batteries face issues with dendrite growth that can lead to internal short circuits and ignition due to excessive dendrite penetration through the separator, necessitating effective cell balancing methods and devices.
Innovation Solution
A cell balancing method and device that employs a balancing profile with pulse and continuous discharge cycles, controlled by a controller, using a balancing resistor and switch, and temperature monitoring to suppress dendrite growth.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If continuous discharge is performed for cell balancing, then cell voltage is reduced effectively, but dendrite growth is promoted due to sustained current flow
Solution Approach 1:
The patent applies periodic action by switching the discharge mode between pulse discharge and continuous discharge based on temperature conditions. When temperature is below the threshold, pulse discharge with specific duty cycle (e.g., 50%) is used; when temperature exceeds the threshold, the system switches to continuous discharge or stops discharge temporarily. This periodic switching between different discharge modes prevents sustained current flow that promotes dendrite growth while maintaining cell balancing efficiency.
2Object-affected harmful factors
If pulse discharge with high frequency is applied to suppress dendrite, then dendrite growth is inhibited, but cell balancing speed decreases
Solution Approach 1:
The patent applies dynamics by making the discharge mode adjustable and adaptive rather than fixed. The system dynamically switches between pulse discharge mode (with adjustable pulse width and duty cycle) and continuous discharge mode based on real-time temperature monitoring. This dynamic adjustment allows the system to optimize between dendrite suppression and balancing speed: using pulse discharge at lower temperatures for safety, and switching to continuous discharge when temperature conditions permit faster balancing.
Solution Approach 2:
The patent applies parameter changes by modifying discharge parameters (current magnitude, pulse width, duty cycle) based on temperature conditions. The controller adjusts these parameters dynamically: at lower temperatures, it uses pulse discharge with specific parameters; when temperature rises above the threshold, it changes to continuous discharge with different parameters or stops discharge temporarily. This parameter adaptation resolves the contradiction by allowing aggressive pulse parameters when safe and more efficient continuous parameters when needed.
3Object-affected harmful factors
If temperature monitoring and mode switching is implemented, then dendrite suppression is improved, but device complexity increases
Solution Approach 1:
The patent applies feedback by implementing a closed-loop control system that continuously monitors cell temperature and adjusts the discharge mode accordingly. The temperature sensor provides real-time feedback to the controller, which compares the temperature against a predetermined threshold and automatically switches between pulse discharge and continuous discharge modes. This feedback mechanism simplifies the control logic compared to complex algorithms, using a straightforward threshold-based decision rule that is easy to implement and maintain.
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 method effectively suppresses dendrite growth by resonating and decomposing existing dendrites, ensuring safe and efficient battery operation.
Implementation Method 1
The balancing profile may include a pulse period and a duty cycle set based on a natural frequency of a dendrite. The balancing device may be further configured to perform the pulse discharge according to a pulse signal that satisfies the pulse period and the duty cycle.
Data Source
AI summary
The present disclosure relates to a cell balancing method and a cell balancing device performing the cell balancing method, and a battery pack. The cell balancing device may include: a storage device that storage a balancing profile for cell balancing; a balancing device configured to perform a discharge function for cell balancing of a plurality of battery cells; and a first controller configured to control the balancing device to perform pulse discharge for a balancing target battery cell selected from among the plurality of battery cells referring to the balancing profile if the cell balancing is required. The balancing profile may include a pulse period and a duty cycle set based on a natural frequency of a dendrite. The balancing device may be further configured to perform the pulse discharge according to a pulse signal that satisfies the pulse period and the duty cycle.