Battery Management Device Active Passive Cell Equalization
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Solution Overview
Problem
Existing methods for equalizing lithium-ion battery cell voltages, either passive or active, face inefficiencies such as energy loss and increased component complexity, which affect power efficiency and cost.
Innovation Solution
A management device with power source circuits, discharge circuits, voltage detection circuits, and a controlling circuit that selectively charges or discharges cells to equalize voltages across series cell groups, allowing for simultaneous active and passive balancing to improve power efficiency without complicating the component configuration.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If passive equalization method is used, then component configuration is simplified, but power efficiency deteriorates due to energy loss and heat generation
Solution Approach 1:
The patent segments the equalization process into two distinct stages: cell-level equalization using power source circuits for individual cells, and module-level equalization using discharge circuits for series cell groups. This segmentation allows each stage to use the most appropriate method (active for cells, passive for modules) thereby resolving the contradiction between component simplicity and energy efficiency.
Solution Approach 2:
The patent applies different equalization qualities to different levels of the battery system. At the cell level, active equalization with power source circuits is used to prevent energy loss. At the module level, passive equalization with discharge circuits is used to maintain component simplicity. This local differentiation resolves the contradiction by optimizing each level independently.
2Loss of energy
If active equalization method is used, then power efficiency is improved, but component configuration becomes complicated and cost increases
Solution Approach 1:
The patent limits active equalization to only the cell level using power source circuits, while using passive discharge circuits at the module level. This segmentation reduces the overall component complexity compared to full active equalization, while still capturing the energy efficiency benefits where they matter most (at the cell level).
Solution Approach 2:
The patent extracts the active equalization function to only where it is most needed (individual cell level), and removes it from the module level where passive equalization suffices. This extraction reduces component complexity while preserving essential power efficiency benefits.
3Device complexity
If discharge resistors are connected to each cell for passive equalization, then component configuration is simple, but energy is wasted and heat is generated
Solution Approach 1:
The patent segments the discharge function to operate only at the module level (series cell group level) rather than at each individual cell level. This reduces the total number of discharge resistors and associated heat generation points, while still achieving equalization by discharging entire modules to match the lowest-voltage module.
Solution Approach 2:
The patent merges multiple cells into series cell groups (modules) and applies a single discharge circuit to each group rather than individual discharge resistors to each cell. This merging reduces component count and consolidates heat generation, making thermal management more efficient.
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 power efficiency by reducing energy loss and component complexity, enabling effective voltage equalization across lithium-ion battery cells while maintaining a simplified configuration.
Implementation Method 1
a plurality of power source circuits connected respectively to a plurality of series cell groups each including a plurality of cells connected in series, the plurality of power source circuits each being configured to be able to selectively charge any one of the plurality of cells included in each of the series cell groups by using a voltage across each of the plurality of series cell groups
Implementation Method 2
In the passive method, discharge resistors are connected to a plurality of cells connected in serial, respectively, and the cells other than the lowest-voltage cell are discharged
Data Source
AI summary
A plurality of power source circuits is each configured to be able to selectively charge any one of a plurality of cells included in each of series cell groups by using a voltage across each of series cell groups. The plurality of discharge circuits are each configured to be able to discharge a capacity stored in each of series cell groups. A controlling circuit equalizes the states of the plurality of cells included in each of the series cell groups by using the plurality of power source circuits. The controlling circuit equalizes the states of the plurality of series cell groups by using the plurality of discharge circuits.