Variable Duration Battery Cell Balancing via Transformer
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Solution Overview
Problem
Existing battery cell balancing methods, such as passive and active balancing, face inefficiencies and complexity, particularly in reducing charging time and increasing energy efficiency, while avoiding unnecessary switching that degrades efficiency and reduces switch life.
Innovation Solution
A method and system using a transformer arrangement with a controller to discharge charge from the highest charged cell to the lowest charged cell, with variable duration discharge and charge time periods based on charge differences, allowing for efficient energy transfer and balancing across cells in a vehicle battery pack.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If active balancing methods (charge shuttling or energy converting) are used to reduce charging time and increase energy efficiency, then cell balancing speed and energy efficiency improve, but device complexity and switching requirements increase
Solution Approach 1:
The patent introduces a capacitor as an intermediary energy storage element that mediates charge transfer between cells. The capacitor accumulates charge from high-voltage cells and releases it to low-voltage cells, enabling active balancing without requiring complex continuous switching circuits. This intermediary approach simplifies the overall system while maintaining fast balancing capability.
Solution Approach 2:
The patent employs periodic switching of the capacitor connection between different cells in series. By systematically connecting the capacitor to each cell in sequence during charging, the system achieves progressive charge redistribution. This periodic action enables efficient balancing across multiple cells using simple switching logic rather than complex continuous control.
2Loss of time
If frequent switching is used to speed up charge redistribution, then cell equalization time decreases, but switch life reduces and high-frequency noise increases
Solution Approach 1:
The patent uses structured periodic switching where the capacitor is connected to each cell in sequence for defined time intervals. This systematic approach achieves charge redistribution without requiring excessive switching frequency. The periodic nature allows sufficient charge transfer during each connection phase while minimizing total switching events, thereby extending switch life and reducing high-frequency noise generation.
3Loss of energy
If charge is continuously transferred from highest to lowest charged cell, then balancing efficiency improves, but unnecessary switching occurs when intermediate cells become highest charged
Solution Approach 1:
The patent incorporates monitoring of individual cell voltages to determine which cell currently has the highest charge. This feedback mechanism allows the system to dynamically adjust which cell receives charge from the capacitor, ensuring that charge transfer always occurs from the actual highest-charged cell to the lowest-charged cell. This prevents energy-wasting switching operations while maintaining optimal balancing efficiency.
Solution Approach 2:
The patent implements dynamic reconfiguration of the capacitor connections based on real-time cell charge states. Rather than fixed sequential switching, the system adapts its switching pattern to follow the changing charge distribution among cells. This dynamic approach ensures that the capacitor always connects to the current highest-charged cell for discharge and the current lowest-charged cell for charging, maximizing balancing efficiency while minimizing unnecessary switching.
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
This approach enhances energy efficiency and reduces charging time by dynamically adjusting discharge and charge periods, effectively balancing cell charges and extending switch life by minimizing high-frequency noise and unnecessary switching.
Implementation Method 1
A method and system using a transformer arrangement with a controller to discharge charge from the highest charged cell to the lowest charged cell
Data Source
AI summary
A method and a system for balancing cells of a vehicle battery includes discharging charge from a highest charged cell for a discharge time period dependent on a charge difference between the highest charged cell and a lowest charged cell at a given time. The cells may be charged with the discharge charge during a charge time period.