Series Resonance Circuit for Cell Voltage Equalization

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Solution Overview

Problem

When equalizing voltages in serially connected cells, a significant potential difference can lead to excessive current flow, imposing a burden on the receiving cell, potentially damaging it.

Innovation Solution

A power storage device and method that utilize a series resonance circuit to transfer energy between equal numbers of cells, selectively connecting cells to the circuit to minimize current flow and evenly distribute energy, thereby reducing the burden on individual cells during voltage equalization.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If voltage equalization is performed by direct connection between cells with significant potential difference, then voltage equalization can be achieved, but excessive current flows to the receiving cell causing burden and potential damage

Engineering Contradiction:
Improvecell safetyVSAvoidexcessive current
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent introduces a series resonance circuit as an intermediary between the power supply cell and power reception cells. This resonance circuit includes a reactor and capacitor that enable energy transfer through resonant oscillation, preventing direct connection and thus avoiding excessive current flow to the receiving cell while still achieving voltage equalization

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent utilizes periodic resonant oscillation in the series resonance circuit to transfer energy between cells. The resonance circuit operates at a specific frequency where the inductive reactance of the reactor equals the capacitive reactance of the capacitor, creating periodic energy exchange that safely equalizes voltages without causing harmful current spikes

Inventive Principle:
Principle #19Periodic action

2Object-affected harmful factors

If series resonance circuit is used for energy transfer, then current flow is minimized and burden on cells is reduced, but device complexity increases

Engineering Contradiction:
Improvecurrent flowVSAvoidcircuit configuration
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent changes the operating parameters of the resonance circuit by tuning the reactor and capacitor values to achieve resonance at a specific frequency. This parameter optimization allows the circuit to operate efficiently with minimal current flow while maintaining manageable complexity through standardized component selection

Inventive Principle:
Principle #35Parameter changes

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 effectively suppresses the burden on cells during voltage equalization, enabling a stable and efficient active cell balancing process with reduced current flow and improved voltage equalization speed.

Implementation Method 1

a series resonance circuit 120 having a reactor 121 and a capacitor 122 connected in series

Methodology Applied
Scientific EffectSeries resonance: Resonance

Data Source

PatentEP3051660B1Electricity storage device and electricity storage control method
Publication Date: 2023.01.11 MURATA MFG CO LTD
  • EP3051660B1 patent drawingFigure 1A~1B
  • EP3051660B1 patent drawingFigure 2A~2B
  • EP3051660B1 patent drawingFigure 3A~3B

AI summary

The present disclosure provides a power storage device, a power storage control device, and a power storage control method for suppressing a burden imposed on a cell when voltages of cells are equalized. A power storage device includes: a plurality of cells which are connected in series; a series resonance circuit configured to include a reactor and a capacitor; and a power storage control device configured to control a connection state of the cells and the series resonance circuit. The power storage control device causes energy to be transferred between equal numbers of cells via the series resonance circuit.