Battery Current Balancing Apparatus Using Dummy Current Injection
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
In battery devices, uneven circuit currents among units lead to uneven discharging and residual capacities, causing premature overdischarge in some cells and preventing full charging of others, resulting in inefficient charging and potential cell deterioration.
Innovation Solution
A circuit current balancing apparatus comprising comparators and current sources that compare voltage and current levels across units, adding or subtracting dummy currents to equalize circuit currents, ensuring all units are fully charged and prolonging battery life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If battery cells are connected in series to increase voltage and capacity, then the overall battery performance is improved, but circuit currents become uneven among units causing some cells to overdischarge while others are not fully charged
Solution Approach 1:
The battery device is divided into multiple independent units, each with its own analog preprocessing circuit and controller. This segmentation allows independent monitoring and control of each unit's current, enabling detection and correction of current imbalance while maintaining the overall series connection for high voltage and capacity.
Solution Approach 2:
Each unit is equipped with an analog preprocessing circuit that continuously monitors circuit current and provides feedback to the controller. Based on this feedback, the controller adjusts switching elements to regulate current flow, ensuring all units operate within safe limits and maintain balanced charging states.
2Loss of time
If charging is stopped when the first battery cell stack reaches full charge, then charging time is reduced, but other battery cell stacks remain undercharged due to current unevenness
Solution Approach 1:
The charging system dynamically adjusts the charging current for each unit based on real-time monitoring of cell stack states. Instead of using a fixed charging current, the controller modulates the current to each unit according to its specific charge level and acceptance rate, allowing all units to reach full charge simultaneously and efficiently.
Solution Approach 2:
The system changes the charging current parameter for each unit based on its state of charge and performance characteristics. By dynamically adjusting current parameters rather than maintaining a constant current, the system achieves both fast charging and uniform charging across all battery cell stacks.
3Adaptability or versatility
If switching elements are used to control battery cell connections, then flexibility in charge/discharge control is improved, but circuit current imbalance occurs due to different resistance values
Solution Approach 1:
Each unit is equipped with dedicated current sensing and control circuitry tailored to its specific characteristics. The analog preprocessing circuits and controllers are locally configured to monitor and adjust current for each unit, compensating for differences in resistance and other parameters, thereby maintaining current balance while preserving control flexibility.
Solution Approach 2:
The system dynamically adjusts operational parameters such as switching timing and current magnitude for each unit based on real-time measurements. This parameter adaptation allows the system to maintain balanced currents across units with different resistance values while retaining the flexibility to respond to varying charge and discharge conditions.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
A circuit current balancing apparatus balances circuit currents among units of a battery device. The circuit current balancing apparatus is provided with a plurality of cell stacks respectively composed of at least one cell. The apparatus balances a circuit current of a control circuit connected to each of the plurality of cell stacks for controlling and monitoring a status of the cell stack. The apparatus also includes a comparator for calculating and outputting a voltage difference between an output voltage of the corresponding cell stack and a voltage of the control circuit connected to the corresponding cell stack, and a current source for adding or subtract a dummy current to/from a circuit current of the control circuit in correspondence with the output of the comparator.