Inductor-Based Power Transfer Circuit for Battery Cell Balancing

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Solution Overview

Problem

Conventional power transfer circuits for rechargeable battery cells generate heat and consume unnecessary power, leading to reduced battery performance and potential damage to the controller, while attempting to balance cell voltages.

Innovation Solution

A power transfer circuit utilizing an inductor connected to two stacked rechargeable battery cells in parallel, with switches and comparators to detect voltage differences and manage power transfer between cells, allowing for efficient balancing without excessive power consumption.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If a conventional balance circuit with resistors and internal distribution paths is used to balance battery cells, then voltage balance among cells is achieved, but heat is generated in the distribution circuits and controller, potentially damaging the controller

Engineering Contradiction:

Improvevoltage balance among battery cellsVSAvoidheat generation in controller

Core Design Contradiction:

Stability of the object's compositionVSTemperature

Solution Approach 1:

The patent introduces an inductor as an intermediary component between battery cells to enable power transfer. The inductor acts as a magnetic coupling mediator that transfers energy from high-voltage cells to low-voltage cells without direct electrical connection through the controller, thus avoiding heat generation in the controller while achieving voltage balance

Inventive Principle:

Principle #24Intermediary (Mediator)

2Stability of the object's composition

If a conventional balance circuit with resistors is used to balance battery cells, then voltage balance among cells is achieved, but power is consumed from the battery cell with higher voltage, reducing battery performance

Engineering Contradiction:

Improvevoltage balance among battery cellsVSAvoidpower consumption from battery

Core Design Contradiction:

Stability of the object's compositionVSUse of energy by moving object

Solution Approach 1:

The inductor serves as an energy transfer intermediary that enables direct power transfer from high-voltage battery cells to low-voltage battery cells through magnetic coupling. This eliminates the need to dissipate energy as heat through resistors, thereby reducing power consumption and preserving battery performance while achieving voltage balance

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stability of the object's composition

If resistors are used in the balance circuit to control current distribution, then voltage balance is achieved, but heat is generated in the distribution circuits

Engineering Contradiction:

Improvevoltage balance among battery cellsVSAvoidenergy loss as heat in distribution circuits

Core Design Contradiction:

Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The inductor replaces resistors as the control element in the balance circuit. By using magnetic coupling through the inductor, power is transferred between battery cells without the need for resistive current control, eliminating energy loss as heat in the distribution circuits while maintaining voltage balance

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the resistive electrical control mechanism with an inductive magnetic coupling mechanism. This substitution changes the fundamental method of energy transfer from resistive dissipation to magnetic field-based energy transfer, reducing energy loss and heat generation

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 effectively balances rechargeable battery cells by buffering power from cells with higher state of charge to those with lower state of charge, reducing heat generation and power consumption, thereby enhancing battery performance and extending cell life.

Implementation Method 1

an inductor respectively linked to two stacked rechargeable battery cells in parallel but not electrically conducted where the two stacked rechargeable battery cells are connected in series, for storing power and releasing stored power

Methodology Applied

Scientific EffectElectromagnetic Induction: Electromagnetic Induction

Data Source

PatentUS9595836B2Power transfer circuit for achieving power transfer between stacked rechargeable battery cells

Publication Date: 2017.03.14 SILICON INTEGRATED SYSTEMS CORP

AI summary

A power transfer circuit for achieving power transfer between stacked rechargeable battery cells is disclosed. The power transfer circuit includes an inductor, a first switch, a second switch and a controller. A loop of the rechargeable battery cell having higher power and the inductor is conducted so that the inductor stores power until the current flowing through the inductor meets the cutoff amount. Then, a loop of the rechargeable battery cell having lower power and the inductor is conducted so that the inductor releases the power saved in the inductor to the rechargeable battery cell having lower power until current flowing through the inductor changes direction. Therefore, balance between the rechargeable battery cells can be achieved.