Battery Equalization Circuit With Inductor Clamp Switching
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Solution Overview
Problem
Existing energy transfer circuits for battery packs with multiple cells in series face challenges such as increased heat generation, complex circuit configurations, and potential switch malfunctions due to spike voltages and noise, especially in high-current equalization processes.
Innovation Solution
An energy transfer circuit with a cell selection circuit, inductor, and clamp circuit controlled by a controller to manage inductor current flow, using diode-connected switching elements to prevent spike voltages and ensure safe, reliable energy transfer between cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the passive equalization method is used with a discharge resistor, then the circuit configuration remains simple and low cost, but the heat generation amount increases and power efficiency decreases
Solution Approach 1:
The patent converts the harmful effect of energy dissipation into a beneficial energy transfer process. Instead of dissipating energy as heat through resistors, the invention uses an inductor to transfer energy from cells with higher capacity to cells with lower capacity, thereby eliminating the harmful heat generation while achieving the equalization goal.
Solution Approach 2:
The patent replaces the passive electrical resistance-based equalization system with an active inductor-based energy transfer system. This substitution transforms the equalization process from a dissipative mechanical-like process (resistor) to an active energy storage and transfer process (inductor), improving overall system efficiency.
2Power
If the number of series connections of cells is increased to increase energy capacity, then the battery pack output increases, but the heat generation amount during equalization increases and heat dissipation area becomes insufficient
Solution Approach 1:
The patent addresses the heat dissipation problem by converting the harmful heat generation into useful energy transfer. The inductor-based active equalization method transfers energy between cells rather than dissipating it as heat, thereby solving the heat dissipation constraint while maintaining the ability to handle high-power battery packs with increased series connections.
3Adaptability or versatility
If a cell selection circuit is added to enable arbitrary cell selection for energy transfer, then energy transfer flexibility increases, but the number of wirings and switches increases
Solution Approach 1:
The patent applies segmentation by dividing the battery pack into multiple independent modules, where each module contains a subset of cells that can be equalized independently. This modular approach allows for flexible cell selection and energy transfer within each module while reducing the overall complexity of wirings and switches compared to a fully interconnected system.
4Productivity
If the equalization time is reduced by applying large current, then productivity increases, but the heat generation amount increases
Solution Approach 1:
The patent resolves the contradiction between equalization speed and heat generation by converting the harmful heat effect into beneficial energy transfer. The inductor-based active equalization method enables fast equalization through controlled energy transfer while avoiding the heat generation that would normally accompany high-current passive equalization, thus achieving both high productivity and low energy loss.
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 solution provides a highly reliable and safe energy transfer circuit that reduces heat loss and prevents switch malfunctions, ensuring efficient equalization of cell capacities in battery packs.
Implementation Method 1
an energy transfer circuit includes an inductor L1
Implementation Method 2
two switching elements, having diodes, are connected in series and formed in a state where the diodes are in opposite directions
Data Source
Figure 1
Figure 2(a)~2(h)
Figure 3(a)~3(c)
AI summary
Cell selection circuit (11) includes a plurality of first wiring switches (S1, S5, and S9) that selectively connect one of both ends of a selected cell to first wiring (W1) and at least one second wiring switch (S4 or S8) that selectively connects the other end of both the ends of the selected cell to second wiring (W2). Clamp circuit (12) includes clamp switches (Scl to Sc4) for forming a closed loop including inductor (L1) in a state where cell selection circuit (11) does not select any cell. Controller (13) turns on all of a plurality of switching elements forming a discharge path after the clamp state is ended, and then turns on a part of a plurality of switching elements constituting clamp switch (Sc2) before the state is switched to a next clamp state.