Common and dual mode chokes for automotive applications in ... · applications in DC and AC conditions for up to 150°C with manganese zinkand nanocrystal material September 2019

© KEMET Electronics. All Rights Reserved.

Common and dual mode chokes for automotive applications in DC and AC conditions for up to 150°C with manganese zink and nanocrystal material

September 2019

E-mobility applications of a few hundred volt and in inverters require proper noise filtering which is compact in design and high in performance. KEMET offers customized solutions for all voltage levels with proprietary materials. This webinar will give you an overview of the possibilities to comply with car manufacturer OEM interference reduction requirements. Applications such as electronic power steering, drives up to 15…20kW in general and heating / air conditioning systems.

© KEMET Electronics. All Rights Reserved. 2

High temperature common mode chokes for automotive power applications

• Automotive demand for EMI attenuation / interference separation• Differential-, common- & dual mode chokes• Behavior of soft magnetic material (Ni-Zn – MnZn – Nanocrystal)• Magnetic saturation behavior of different materials• Temperature rise in unforced air conditions• Product availability


• Depending on the noise source of automotive IGBT´s or other semiconductor “switches” the interference filtering need to be adjusted depending on the topology and technology used.

• Switching frequency and harmonics assign the filter requirement• Filter requirements link to the right soft magnetic material and

topology of the filter (common or differential mode attenuation)• Automotive OEMs specify maximum interference level for

conducted and radiated interference to avoid disturbances and malfunction

High temperature common mode chokes for automotive power applications


Typical OEM requirement for EMC

150kHz to 30MHz

Low interference requirementaround 100MHz range

Keep FM radio independent from interferences of power electronics

Predominant common mode behavior neededDifferential mode behavior needed

avgpeak

avg limit

peak limit


Filter basicsAttenuation of differential and common mode interference

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雑音端子電圧

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Differential mode interference

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Common mode interference

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[dB (μV)]Usual view of EMC interference

Common and differential mode interferences measured and monitored combined

InterferenceSplitter

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ー differentialー common mode

Separation to differential and common mode interference

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Y capX cap

DMCCMC

Asynchronyinterferences

synchroninterferences

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Common mode choke

Comparison of differential and common mode chokes Differential mode choke

Independent of the current direction-interference will be filtered

according to the impedance at the frequency creating losses that

transfer into heat energyPermanent magnetic flux is present at mains frequency and interference

filtering frequency

The material need high magnetic saturation capabilities

Magnetic flux generated from mains supply AC or DC is compensated by counter wound coils

Only common mode interference generates a magnetic field and flux that transfers core loss energy into thermal energy

The needed magnetic saturation onlyfor common mode interference current

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Common mode choke

Common mode choke with increased differential inductance

Magnetic flux generated from mains supply AC or DC is compensated by counter wound coils

Only common mode interference generates a magnetic field and flux that transfers core loss energy into thermal energy

The needed magnetic saturation onlyfor common mode interference current

„Dual Mode“ Choke

Common mode interference initiates magnetic flux and a separate magnetic path initiates differential mode current around a single coil

Material need good magnetic saturation capabilities

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Typical 2 stage noise filter circuit

Element attenuating “differential mode interferences”

Elements with blue letters (CX1 - Ln1 - CX2 – Ln2) attenuating asynchronous interferencesIn this circuit diagram, the 4th order low pass filter is formed.

Elements with red letters (Lc1 - Cy1 - Lc2 – Cy2) attenuating synchronous interferencesIn this circuit diagram, the 4th order low pass filter is formed.

Element attenuating “common mode interferences”

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Common mode choke with differential inductanceHigh voltage 500 to 1000VDC

• Example within 20A/400VDC – maximum Power 8kW (i.e. HVDC power steering)• Requirement: Differential and common mode noise attenuation per OEM spec

Common mode L (1.15 mH@100kHz)

SCN Series

Differential mode L (14.6 uH@100kHz)

Differential modecharacteristics improvedby oval shaped core


Temperature requirements

• Maximum ambient conditions require the proper selection / design of the filtering components (capacitors, chokes & ferrites)

• Chokes convert the high frequency interferences into core loss thatincreases the heat of the component, impedance at interference current guides into power loss

• Pcopper = I2 * RDC * 2 / example with 5mΩ & 20A à 4W• Maximum temperature component = max. ambient + heat rise• Thermal resistance of component depends on board layout and

copper thickness and thermal attachment to chassis• To assign a max component temperature the plastic material of the

choke, the curie temperature of the magnetic material and the insulation material of the copper wire needs to be selected


Basics automotive EMC summary

• Depending on the power switching topology used different filtering is required (frequency / level / common- or differential mode)

• Heat dissipation needs to be kept under control à DC resistance is one component with thermal resistance

• If nothing was tested a simulation of interferences is helpful toevaluate a filter properly

• Information needed (KEMET wish list): ambient temperaturecurrent (max & rated)DC resistance wishmechanical orientation – space for filteringimpedance @100kHz or inductance required


Behavior of soft magnetic material

• Permeability changes over frequency and temperature• Curie temperature assigns working temperature range• Magnetic saturation & real inductance depend on interference current


Frequency dependence of magnetic material

ß Nanocrystal material (20k…60k) à Automotive

Automotive

Automotive

10HT for automotiveunder development

T

T


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S18H

10H

7H 7HT(new)

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S15H

Magnetic componentsmagnetic material temperature dependance

Ferrite core CMC

Automotive MnZnMaterial


Common mode chokes

Φ1.8-3P 10T 2phase

Common mode current superposition characteristics

(Coil: FR47 D1.8-3P 10T)

Spec on Document

Test conditions：100kHz, 0.1mA, 23℃

Spec with current


• Different magnetic materials permeability behave differently over frequency, temperature and with saturation

Permeability 1 to 1 translates into inductance


• The DC current creates heat through the copper heat rise• Noise currents create heat through initiating magnetic flux

• Example:

RDC = 4mΩ (DC resistance of copper wire)IDC = 15A (DC current)ICMC = 90mA@100kHz (unbiased current / common mode current)Z100kHz = 900Ω (Impedance at 100kHz)

Ploss = 15A2 * 4mΩ + 90mA2 * 900Ω = 0.9W + 7.3W = 8.2W(rough expectation only with main disturbing frequency)

Influence of ambient condition and Ploss


Product availability

• Today no standard parts (catalog) are available• Due to various mechanical standards KEMET can semi-customize

products in specific existing shapes with different wires (diameter, turns, number of parallel wires) ->> for smaller volumes

• Full customization is available for volumes from ~ 500k pcs EAU upwards and 5 to 10 years lifetime of projects

• If applicable existing designs can be used for smaller quantities


Common mode chokes examplescustomized ferrite or nanocrystal choke solutions up to 60A / 1000VDC

FR222mH-15A-NC

29x22x27.5mm

SCF292mH-30A-NC

SCF251.2mH-30A-NC

34x23x34.5mm 40x20x36mmFR19

200µH-20A-5HT

28x22.5x21mm

SC19130µH-60A-7HT*UD

26x21x13mm

Temperature ranges up to 155°C ambientAEC-Q200 / PPAP / IMDS / IATF plant

experienced engineering team in Japan

SCF334mH-30A-NC

40x38x30mm

SCN4030300µH-25A-5HT


Typical customer proposal


What if the currents are higher ?

• High currents >100A DC require different solutions to attenuate interferences as a classic choke would have to high losses and heat rise to survive the application ambient

• This might be necessary for drive train converters and applicationswith lower DC voltage (15kW: 37.5A @400V / 312A @48V

• In that case it is possible to use busbar ferrites which can be developed as differential-, common- or dual mode

• Basically this is a one turn choke


15nH


Automotive Components40 years successful automotive supplier & innovative portfolio evolution

Metal composite SMDNew automotive grade series MPCV & MPLCV

for DC/DC conversion applications & computing

Power & BoostCustomized series i.e. for LED headlight, electric air conditioning & drive train voltage boost

Ferrite ChokesNoise filtering (common mode) chokes for

e-compressor and DC/DC power conversion

Flexsuppression & Ferrite CoresRadiated noise suppression for power high frequency and digital communication applications

MagneticComponentsStrengh: Own

design & material technology

AEC-Q200Up to 155°C today


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Common and dual mode chokes for automotive applications in ... · applications in DC and AC conditions for up to 150°C with manganese zinkand nanocrystal material September 2019