Ferrite Shield Induction Heating for EV Battery Wireless Charging

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Solution Overview

Problem

Current heating devices for traction batteries during wireless charging divert power from the charging process to pre-heat the battery, reducing charging efficiency due to the use of external resistive filaments.

Innovation Solution

A heating device with an induction coil surrounded by a ferrite shield, utilizing a heat transfer circuit with a circulated fluid to transfer heat from the ferrite shield to the battery, reducing the need for external heating and enhancing energy efficiency by suppressing stray fields and leveraging the ceramic's heating process.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If an external resistive filament is used to heat the battery during wireless charging, then the battery can be maintained within a suitable temperature range, but the charging power is reduced due to power being siphoned off for heating

Engineering Contradiction:
Improvebattery temperatureVSAvoidcharging power
Core Design Contradiction:
TemperatureVSPower

Solution Approach 1:

The patent converts the harmful stray electromagnetic fields into beneficial heat for the battery. The ferrite shield captures stray fields that would otherwise be wasted energy and converts them to thermal energy through hysteresis losses, directly heating the battery without reducing charging power. This transforms a parasitic effect into a useful heating mechanism.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The ferrite shield acts as an intermediary between the electromagnetic field and the battery. It intercepts stray electromagnetic fields and transfers the converted thermal energy to the battery through thermal conduction, mediating the energy transfer process and enabling heating without direct electrical connection or power siphoning.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a ferrite shield is implemented around the induction coil to suppress stray fields, then external heating is reduced, but the ferrite shield itself generates heat through field suppression that needs to be managed

Engineering Contradiction:
Improvestray field heatingVSAvoidferrite shield temperature
Core Design Contradiction:
Object-affected harmful factorsVSTemperature

Solution Approach 1:

The patent converts the heat generated by the ferrite shield during field suppression from a waste product into a useful heating source for the battery. The thermal energy that would otherwise be lost is redirected to warm the battery, turning a potential harmful side effect into a beneficial contribution to temperature management.

Inventive Principle:
Principle #22Blessing in disguise (Convert harm into benefit)

Solution Approach 2:

The ferrite shield performs dual functionality: it suppresses stray electromagnetic fields while simultaneously serving as a heat source for the battery. The heat generated during its primary function of field suppression is automatically utilized to warm the battery, making the system self-sufficient for thermal management without requiring external heating elements.

Inventive Principle:
Principle #25Self-service

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 solution improves energy efficiency by reducing the demand for resistive heating, allowing more power to be diverted to battery charging while maintaining effective heating, thereby enhancing low-temperature battery performance.

Implementation Method 1

Since these microfields involve the flipping of charges from the ferromagentic ceramic, the ceramic goes through a heating process during field suppression.

Methodology Applied
Scientific EffectHysteresis heating: Magnetic Hysteresis

Implementation Method 2

Wireless charging of a traction battery of an electric vehicle occurs through the electromagnetic resonance between two induction coils

Methodology Applied
Scientific EffectElectromagnetic resonance: Resonance

Implementation Method 3

heat transfer means being a heating circuit adapted to transfer heat from the ferrite shield to the traction battery by means of a circulated fluid

Methodology Applied
Scientific EffectConvection: Convection

Data Source

PatentEP3495191B1Heating device for a traction battery of a vehicle, and vehicle having the same
Publication Date: 2021.03.03 BAYERISCHE MOTOREN WERKE AG
  • EP3495191B1 patent drawingFigure 1
  • EP3495191B1 patent drawingFigure 2~3

AI summary

The invention relates to a heating device for a traction battery (10) of a vehicle, comprising: an induction coil (4) for wireless charging of the traction battery (10); a ferrite shield (6) surrounding the induction coil (4), and heat transfer means (7; 11) for transferring heat from the ferrite shield (6) to the traction battery (10) for heating the traction battery (10), wherein the heat transfer means (7; 11) cover at least 10% of the outer surface of the traction battery (10). Further, the invention relates to a vehicle having such a heating device.