Hybrid Battery Cell Equalization Circuit for Lower Energy Loss
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Solution Overview
Problem
Current battery management systems (BMS) either use passive or active equalizers but not both, leading to inefficiencies in voltage balancing across battery cells, which can result in energy loss, reduced capacity, and poor performance.
Innovation Solution
A method for designing an active battery cell equalization circuit or a combined active and passive battery cell equalization circuit, which includes setting the number of cell sections, charge transfer efficiency, and matrix elements to determine equalization circuit currents, battery discharge time, and power loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If passive equalization is used, then cost is reduced, but energy loss increases due to heat dissipation
Solution Approach 1:
The patent combines passive equalization circuits with active equalization circuits into a hybrid system. The passive circuits provide basic voltage balancing through resistive discharge, while active circuits transfer energy between cells to achieve more efficient equalization, thereby reducing overall energy loss while maintaining cost-effectiveness.
Solution Approach 2:
The equalization system is divided into multiple independent equalization circuits, each serving specific cell groups. This segmentation allows the system to apply different equalization strategies (passive or active) to different cell sections based on their specific needs, optimizing the balance between cost and energy efficiency.
2Loss of energy
If active equalization is used, then energy loss is reduced, but cost increases
Solution Approach 1:
The patent merges active equalization circuits with passive equalization circuits in a hybrid configuration. The active circuits handle critical energy transfer tasks where efficiency is paramount, while passive circuits manage less critical equalization needs, thereby reducing overall system cost while maintaining low energy loss.
Solution Approach 2:
Different equalization strategies are applied to different cell groups based on their specific characteristics and requirements. High-priority cell groups with significant voltage imbalances receive active equalization, while other groups use passive equalization, optimizing the balance between cost and energy efficiency locally.
3Device complexity
If only passive equalization is used, then device complexity is reduced, but voltage balancing performance deteriorates
Solution Approach 1:
The patent combines multiple equalization circuits with different operating mechanisms into a unified system. This integration enables the system to achieve superior voltage balancing performance by leveraging the complementary strengths of both passive and active equalization approaches while managing overall complexity through shared control architecture.
Solution Approach 2:
The equalization system dynamically selects and switches between passive and active equalization modes based on real-time battery conditions, cell voltage differences, and system state. This dynamic adaptability allows the system to optimize voltage balancing performance across varying operating conditions while maintaining manageable complexity.
4Reliability
If only active equalization is used, then voltage balancing performance is improved, but device complexity increases
Solution Approach 1:
The patent integrates active equalization circuits with passive equalization circuits to create a hybrid system that achieves high voltage balancing performance. The passive circuits handle routine equalization tasks, reducing the burden on active circuits and thereby managing overall system complexity while maintaining superior balancing performance.
Solution Approach 2:
The system applies active equalization selectively to specific cell groups that require it, rather than uniformly across all cells. This partial application of active equalization reduces the overall complexity of the system while maintaining high voltage balancing performance where it is most needed.
Data Source
AI summary
A method for designing an active battery cell equalization circuit or a combined active battery cell equalization and passive battery cell equalization circuit to be used for equalizing voltage of cell sections in a battery. The method includes setting a number of the cell sections; setting a charge transfer efficiency variable for the equalization circuit; setting a diagonal matrix element for a matrix modeling the equalization circuit; setting a diagonal −1 matrix element for the matrix; setting a discharge capacity value for each cell section; setting a discharge current for the battery; determining equalization circuit currents, battery discharge time, discharge capacity of the cell sections and percentage of rated discharge capacity of the cell sections; setting a median voltage of the cell sections; and determining power loss, energy loss, energy discharge and discharge energy efficiency of the battery.