Inductor Cell-Balancing Circuit for Fast Battery Equalization
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Solution Overview
Problem
As the number of cells in series increases, especially in in-vehicle applications, the passive method of equalization in secondary batteries becomes inefficient due to increased heat generation and longer processing times, necessitating an active method that reduces energy imbalance quickly without generating excessive heat.
Innovation Solution
An energy transfer circuit using an inductor with a cell selection circuit and clamp switches to efficiently transfer energy between cells, allowing for arbitrary cell selection and reducing the number of elements required, thereby minimizing heat generation and processing time.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the passive equalization method is used with increasing number of cells in series, then the circuit configuration remains simple and cost is low, but heat generation increases and equalization time becomes excessively long
Solution Approach 1:
The patent divides the equalization function into modular units by introducing selection switches that can independently connect different cell pairs to the inductor. This segmentation allows parallel equalization operations across multiple cell combinations, significantly reducing total equalization time while maintaining circuit simplicity through repeated use of the same basic equalization module.
Solution Approach 2:
The patent implements dynamic cell selection capability where the controller can arbitrarily select which cells to equalize based on real-time voltage measurements. The selection switches dynamically reconfigure the circuit connections to match the current equalization needs, enabling adaptive equalization strategies that optimize both speed and efficiency for different battery states.
2Productivity
If the active equalization method is used to reduce equalization time, then equalization speed improves, but the number of switches and circuit complexity increase
Solution Approach 1:
The patent makes the inductor a universal energy transfer medium that serves all cell equalization needs. A single inductor can transfer energy between any pair of selected cells through the selection switches, eliminating the need for dedicated inductors for each cell pair. This multi-functional approach dramatically reduces the total number of energy storage elements while maintaining fast active equalization capability.
Solution Approach 2:
The selection switches act as intermediaries that manage energy transfer between cells and the inductor. Instead of direct cell-to-cell connections requiring multiple switches, the selection switches mediate all connections through the single inductor, reducing switch count while enabling flexible arbitrary cell selection and parallel equalization operations.
3Adaptability or versatility
If arbitrary cell selection is implemented for energy transfer, then equalization flexibility improves, but the number of wirings and switches increases
Solution Approach 1:
The patent merges all cell connections to a common inductor node, creating a star-topology wiring structure. All selection switches connect to the inductor's two terminals, consolidating numerous potential cell-to-cell connections into a unified connection scheme. This merging approach enables arbitrary cell selection while minimizing wiring complexity compared to a fully meshed connection structure.
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
The proposed circuit effectively reduces the number of switches and elements needed, enhancing efficiency and safety by actively clamping inductor current, thus achieving rapid energy balancing with minimal heat dissipation and reduced switch control complexity.
Implementation Method 1
an inductor; a cell selection circuit provided between n cells, where n is an integer of two or more, connected in series and the inductor
Implementation Method 2
a clamp switch for forming a closed loop including the inductor
Data Source
AI summary
The controller controls a cell selection circuit to electrically connect both ends of a cell to be discharged among n cells connected in series and both ends of the inductor for a predetermined time. Next, the controller controls the cell selection circuit to electrically cut off the n cells and the inductor, and turn on the clamp switch. Next, the controller turns off the clamp switch, and controls the cell selection circuit to electrically connect both ends of a cell to be charged among the n cells and both ends of the inductor for a predetermined time.