Battery Charge-Rate Control for Balanced Voltage Thresholds
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Lithium-ion batteries are susceptible to damage and safety issues due to overcharging or excessive discharging, leading to potential fires or explosions, and face challenges in maintaining balanced state of charge, especially in applications with flat open circuit voltage characteristics, which can result in uneven battery degradation and reduced lifespan.
Innovation Solution
A battery management system that monitors voltages across multiple batteries and adjusts charge or discharge rates using DC-to-DC converters to ensure all batteries reach a threshold value at the same time, mitigating the effects of 'dead band' operation by reducing or increasing rates independently and adaptively, using historical data and iterative processes to maintain balanced state of charge.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If batteries are charged or discharged at high rates to improve productivity, then energy throughput increases, but batteries may reach voltage thresholds at different times causing uneven degradation and reduced reliability
Solution Approach 1:
The system divides the battery pack into individually controllable segments (batteries or modules), with each having its own DC-to-DC converter. This allows independent control of charge/discharge rates for each battery segment, enabling the system to manage voltage thresholds and state of charge balance separately for each unit while maintaining high overall productivity.
Solution Approach 2:
The control system dynamically adjusts charge and discharge rates in real-time based on monitored voltage levels and state of charge of each individual battery. By continuously adapting operating parameters rather than using fixed rates, the system prevents uneven degradation while maximizing energy throughput across the entire battery pack.
2Manufacturing precision
If individual DC-to-DC converters are used for each battery to enable independent rate control, then battery management precision improves, but device complexity increases
Solution Approach 1:
Each DC-to-DC converter is designed as a multi-functional unit that performs voltage regulation, current control, and state of charge monitoring simultaneously. This universal design allows the system to achieve precise state of charge balance for each battery while reducing the need for separate dedicated components, thereby managing complexity more effectively.
Solution Approach 2:
A central control system acts as an intermediary that coordinates the operation of multiple DC-to-DC converters. This mediator manages communication between converters and the battery management system, enabling precise individual control while centralizing the complexity of coordination and data processing rather than distributing it across all components.
3Ease of operation
If batteries with flat open circuit voltage characteristics are charged at constant rates, then ease of operation is maintained, but measurement precision of state of charge deteriorates
Solution Approach 1:
The system implements continuous feedback monitoring of battery voltage, current, and state of charge for each individual battery. By using feedback from voltage threshold detections and cumulative charge/discharge measurements rather than relying solely on open circuit voltage, the system achieves precise state of charge measurement even for batteries with flat voltage characteristics, while maintaining simple constant rate charging operation.
Data Source
AI summary
A method for managing a plurality of batteries that are electrically coupled together includes (1) monitoring respective voltages of the plurality of batteries and (2) in response to a respective voltage of a first battery of the plurality of batteries reaching a first threshold value at a first time, reducing a charge or discharge rate of the first battery, relative to at least a second battery of the plurality of batteries. Charge and discharge rates may be adaptively managed such that each battery reaches the first threshold value at substantially the same time.