Battery Pack Discharge Current Control From SOH Imbalance
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Solution Overview
Problem
Battery systems face challenges in managing overcharging, overcurrent situations, and varying state of charge (SoC) among battery packs, leading to potential damage, degradation, and inefficient charging processes, particularly in systems with different battery chemistries and arrangements.
Innovation Solution
A system and method that utilize a buck converter to reduce charging voltage, an overcurrent protection circuit to address short circuits, a bypass circuit for series-connected packs, and a controller to determine battery pack configurations and discharge currents based on state of health (SOH), enabling efficient and safe charging and discharging while minimizing inrush currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If fast charging is applied to battery packs with different chemistries, then charging speed is improved, but over-voltage conditions occur in cells with specific chemistries
Solution Approach 1:
The battery pack array is segmented into multiple groups based on battery chemistry type, with each group monitored and controlled independently. This allows fast charging to be applied to compatible chemistries while preventing over-voltage conditions in sensitive chemistries by isolating them into separate control groups.
Solution Approach 2:
Charging parameters such as voltage and current are dynamically adjusted based on the detected battery chemistry type. The system changes electrical parameters to match the specific requirements of each chemistry group, enabling fast charging for chemistries that can tolerate it while maintaining safe parameters for chemistries that are sensitive to over-voltage.
2Device complexity
If series-connected battery packs are charged without bypass circuits, then charging simplicity is maintained, but overcharging occurs in already charged packs
Solution Approach 1:
Bypass circuits are pre-configured in each battery pack and activated automatically when a pack reaches full charge. This preliminary preparation allows the system to quickly divert current around fully charged packs without complex control logic, preventing overcharging while maintaining charging simplicity.
Solution Approach 2:
Bypass circuits act as intermediary pathways that divert charging current around fully charged battery packs. These circuits serve as a mediator between the charging source and the battery array, automatically routing current through alternative paths to prevent overcharging without requiring complex monitoring and control systems.
3Power
If parallel battery pack arrangements are used, then power capacity is increased, but cascading overcurrent situations occur during short circuits
Solution Approach 1:
The parallel battery pack arrangement is segmented into multiple independent groups, each with its own overcurrent protection circuitry. This segmentation isolates short circuit conditions to specific groups, preventing cascading overcurrent from affecting the entire array while maintaining high power capacity through the parallel configuration.
Solution Approach 2:
Overcurrent protection circuits are pre-installed in each parallel battery pack group to cushion against short circuit conditions. These protection mechanisms are prepared in advance and automatically activate during short circuits to limit current flow and prevent catastrophic failure and cascading effects across the parallel arrangement.
4Device complexity
If battery pack configurations are not determined, then system simplicity is maintained, but optimization of charging operations cannot be achieved
Solution Approach 1:
The battery management system automatically detects and determines the configuration of battery packs in the array without requiring external intervention or manual setup. The system self-configures by monitoring electrical characteristics and communication signals from each pack, enabling optimized charging operations while maintaining system simplicity through automated operation.
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 minimizes overcharging, prevents damage from overcurrents, optimizes charging efficiency, and extends the life of battery cells by dynamically managing charging and discharging processes based on the state of health and configuration of battery packs, ensuring safe and efficient power delivery.
Implementation Method 1
a buck converter may be used to reduce a voltage of power used to charge the cells
Data Source
AI summary
Systems and methods are described for managing charging and discharging of battery packs. In one or more aspects, a system and method are provided to minimize overcharging of battery cells of specific battery chemistries while still enabling fast charging cycles. In other aspects, a buck converter may be used to reduce a voltage of power used to charge the cells. In further aspects, a fast overcurrent protection circuit is described to address situations involving internal short circuits of a battery cell or battery pack. In yet further aspects, a bypass circuit is provided in series-connected battery packs to improve the charging of undercharged battery packs while also increasing the efficiency of the overall charging process. In other aspects, a circuit is provided that permits a controller to determine a configuration of battery packs. In yet further aspects, a system may determine a discharge current for a collection of battery packs based on each battery pack's state of health (SOH) and forward that determination to an external device.