Cell Equalization Circuit With Filtered Inductor Overcurrent Detection

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Solution Overview

Problem

Existing active equalizing circuits using inductors face challenges in achieving accurate overcurrent protection due to high frequency noise interference, leading to inefficient circuit design and increased costs.

Innovation Solution

An energy transfer circuit with a low-pass filter and overcurrent detection circuit that accurately captures peak current values by clamping the inductor current near its peak, allowing for precise overcurrent protection without excessive circuit scaling.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Duration of action of moving object

If a power supply device is connected between the first battery and the second battery to enable bidirectional power supply, then the electricity storage system can supply power during both day and night, but the system complexity and cost increase due to additional components

Engineering Contradiction:
Improvepower supply durationVSAvoidsystem complexity
Core Design Contradiction:
Duration of action of moving objectVSDevice complexity

Solution Approach 1:

The patent combines the power supply functions of both batteries into a single unified system where the first and second batteries can independently or jointly supply power to the load. The control unit integrates the management of both battery connections, merging what would otherwise be separate power supply systems into one coordinated architecture, thereby achieving extended power supply duration without proportionally increasing system complexity

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The electricity storage system is designed with multi-functionality where the same battery configuration can serve different purposes: during the day, the system can charge from solar panels and supply to load; at night, it can discharge stored energy to continue supplying power. The power supply circuit serves multiple functions by dynamically connecting different battery combinations based on time and power requirements, avoiding the need for completely separate day and night power supply systems

Inventive Principle:
Principle #6Universality (Multi-functionality)

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

Enables highly accurate overcurrent protection at an appropriate circuit scale and cost, optimizing the performance of the inductor and reducing unnecessary waste in the circuit design.

Implementation Method 1

an electricity storage element which is a capacitor connected in parallel with the second battery

Methodology Applied
Scientific EffectCapacitance: Capacitance

Data Source

PatentEP4037124B1Energy transfer circuit, and electricity storage system
Publication Date: 2026.04.15 PANASONIC INTELLECTUAL PROPERTY MANAGEMENT CO LTD
  • EP4037124B1 patent drawingFigure 1
  • EP4037124B1 patent drawingFigure 2
  • EP4037124B1 patent drawingFigure 3(a)~3(h)

AI summary

Cell selection circuit (11) is provided between n cells (C1 to C4) connected in series, where n is an integer of 2 or more, and inductor (L1), and is provided at both ends of the selected cell and both ends of inductor (L1) can be conductive. Clamp circuit (12) includes at least one clamp switch (Scl to Sc4) for forming a closed loop including inductor (L1) in a state where cell selection circuit (11) does not select any cells (C1 to C4). Current detection circuit (Rs, AP1) detects the value of the current flowing through inductor (L1). Low-pass filter (15) band-limits the detection value. Overcurrent detection circuit (16) activates the protection of inductor (L1) when the band-limited detection value exceeds the threshold.