Passive Battery Cell Balancing With a Shared Resistor Circuit
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Solution Overview
Problem
Existing battery packs with series-connected cells face inefficiencies in passive charge balancing due to varying charge and discharge rates, leading to unbalanced conditions that reduce battery life and utilization.
Innovation Solution
A battery management system with a shared balancing resistor and discharge enable switch for each cell, controlled by a controller that iteratively selects cells for discharge to balance charges within an unbalance threshold, optimizing the selection process to minimize circuitry and time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional passive balancing is used with individual resistors for each battery cell, then charge balancing can be achieved, but the circuitry becomes bulky and complex
Solution Approach 1:
The patent merges multiple individual balancing resistors into a single shared balancing resistor that is coupled to multiple battery cells. This consolidation reduces the total number of passive components and simplifies the circuit architecture while maintaining the ability to balance charges across all cells through selective switching.
Solution Approach 2:
The shared balancing resistor serves multiple battery cells simultaneously, making a single component perform the function that would otherwise require multiple separate resistors. This multi-functional approach reduces component count and circuit complexity while preserving charge balancing capability for all connected cells.
2Reliability
If passive balancing is performed sequentially on each battery cell, then charge balancing can be achieved, but the balancing time increases
Solution Approach 1:
The system enables continuous charge balancing across multiple battery cells by allowing the shared resistor to discharge multiple cells in sequence without idle time between operations. The controller manages the switching between cells to ensure continuous balancing action, maximizing the utilization of the balancing circuit throughout the process.
Solution Approach 2:
The controller implements periodic switching between different battery cells connected to the shared balancing resistor. By systematically cycling through unbalanced cells and enabling their discharge through the shared resistor, the system achieves comprehensive balancing of all cells within a optimized time frame rather than performing sequential balancing with idle intervals.
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
Improves the speed and efficiency of passive charge balancing, enhancing battery pack performance and longevity by ensuring all cells reach a balanced state without additional bulky circuitry.
Implementation Method 1
a shared balancing resistor electrically connected to an adjacent battery cell
Data Source
AI summary
Example battery management systems, methods, and computer program products for managing the passive charge balancing of a battery pack are provided. A first example battery management system includes a battery pack, a battery management integrated circuit, and a battery management controller. The battery management integrated circuit includes a discharge circuit for each battery cell, having a shared balancing resistor connected to an adjacent battery cell. The battery management controller electrically coupled to the battery management integrated circuit, and configured to identify a least charged battery cell; iteratively select a plurality of highest charged battery cells, wherein no two highest charged battery cells are adjacent, and wherein each highest charged battery cell of the plurality of highest charged battery cells is greater than the least charged battery cell plus an unbalance threshold; and enable the discharge enable switch associated with each highest charged battery cell.