Active Equalizer Inductor Design for Battery Charge Transfer Efficiency

Solution Overview

Problem

Current battery management systems (BMS) either employ passive or active electronic equalizers (EQU), but not both, limiting the efficiency and cost-effectiveness of battery cell voltage balancing, and there is a need for design aid tools to effectively implement bilevel equalizers (BEQ) that combine both types.

Innovation Solution

An efficiency measuring apparatus and design tools for active EQU units, including FET switches, inductors, and gate drivers, along with a design app and mathematical model, to optimize charge transfer efficiency between battery cell sections.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If passive EQU is used to balance cell voltages, then cost is reduced, but energy loss increases due to heat dissipation

Engineering Contradiction:

ImprovecostVSAvoidenergy loss

Core Design Contradiction:

Ease of manufactureVSLoss of energy

Solution Approach 1:

The battery system is divided into multiple sections, each with its own passive EQU for intra-section balancing. This segmentation allows the use of inexpensive passive EQUs for local balancing while using active EQU only for inter-section balancing, reducing overall energy loss while maintaining cost-effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent introduces passive EQU units as intermediary components within each section. These passive EQUs serve as local balancing mechanisms that prevent excessive voltage divergence within sections, thereby reducing the burden on active EQU and minimizing total energy loss.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Loss of energy

If active EQU is used to balance cell voltages, then energy loss is reduced, but cost increases

Engineering Contradiction:

Improveenergy lossVSAvoidcost

Core Design Contradiction:

Loss of energyVSEase of manufacture

Solution Approach 1:

The battery system is divided into multiple sections, each with its own passive EQU for intra-section balancing. This segmentation allows the use of inexpensive passive EQUs for local balancing while using active EQU only for inter-section balancing, reducing overall energy loss while maintaining cost-effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent combines passive and active EQU approaches into a hybrid bilevel equalization system. Passive EQUs handle local intra-section balancing while active EQU handles inter-section balancing, merging the cost advantages of passive systems with the energy efficiency of active systems.

Inventive Principle:

Principle #5Merging (Combining)

3Reliability

If bilevel equalizer (BEQ) is implemented, then performance approaches active EQU level, but device complexity increases

Engineering Contradiction:

ImproveperformanceVSAvoiddevice complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The battery system is divided into multiple sections, each with its own passive EQU for intra-section balancing. This segmentation allows the use of inexpensive passive EQUs for local balancing while using active EQU only for inter-section balancing, reducing overall energy loss while maintaining cost-effectiveness.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Instead of implementing full active EQU across all cells, the patent applies passive equalization partially at the section level and active equalization only where necessary between sections. This partial action approach achieves most of the performance benefits with significantly reduced complexity.

Inventive Principle:

Principle #16Partial or excessive action

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

Enhances charge transfer efficiency and reduces energy loss by optimizing inductor and FET switch designs, enabling cost-effective bilevel equalization in battery systems.

Implementation Method 1

an inductor electrically coupled between the cell sections, to the drain terminal of the first FET switch and the source terminal of the second FET switch

Methodology Applied

Scientific EffectElectromagnetic induction: Electromagnetic Induction

Data Source

PatentUS12355278B2Efficiency measuring apparatus, active equalizer inductor design tool and equalizer design app

Publication Date: 2025.07.08 MUBENGA NGALULA SANDRINE

AI summary

An efficiency measuring apparatus that measures the efficiency of charge transfer between battery cell sections in an active EQU unit. The apparatus includes a pair of series connected battery cell sections, a first FET switch and a second FET switch. The apparatus further includes an inductor electrically coupled between the cell sections, to the drain terminal of the first FET switch and the source terminal of the second FET switch. The apparatus also includes a gate driver electrically coupled to the gate terminal of the first FET switch, and an oscillator providing a PWM signal to the gate driver, where the gate driver opens and closes the first FET switch to transfer charge from the one cell section to the other one cell section through the inductor.