Innovative power capacitor technologies for wide band-gap ... · Innovative power capacitor technologies for wide band-gap semiconductors Advanced design features for high-frequency

Innovative power capacitor technologies for wide band-gap semiconductorsAdvanced design features for high-frequency applications

Technologies & Products Press Conference 2019

Dr. Lucía CaboFernando Rodríguez

Aluminium & Film Capacitors Business Group Málaga, Spain

October 29, 2019

Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 2

Growing demands challenging power electronics

Integration

EMC

Miniaturi-zation

Lowlosses

High robustnessHigh energy density

INDUSTRIALMOBILITY

MEDICALENERGY


Advanced semiconductors put high demands on the DC link

Challenge for passive components: Not be the bottleneck in new power electronics designs

New Si/SiC/GaN

features

Demands on DC link●Lower switching losses

● Higher switching frequencies and faster on/off performance

● Higher junction temperature

● Lower thermal resistance (package improvement)

● Higher operation temperature

● Heat transferred to the capacitors via the busbar

● Higher current density

● Higher energy efficiency

● Miniaturization

● Suitable for fast transients (dV/dt) and ringing effects


Design goals for high-frequency capacitors

High operating temperature ● High temperature dielectric● Handle heat coming from the semiconductor

busbar● High current capability

Low ESR vs frequency● Minimized losses ● Wider operation bandwidth up to the MHz range● Good performance close and above the

resonance frequency

Low ESL of <10 nH (<5 nH for special designs)● Internal design for high dV/dt levels● Make snubber capacitors unnecessary


Disadvantages of BOPP film

Limited performance at high temperatures

Tmax = 105 °C for high crystalline BOPP

Tmax = 125 °C for some special BOPP grades – with derating

New dielectric for high temperature is neededPolypropylene (PP) is a commonly used standard dielectric in film capacitors. PP is transformed into a biaxially oriented PP (BOPP) film in a sequential stretching process

Advantages of BOPP film

State-of-the-art dielectric

Excellent self-healing properties

Low losses

Low price

Polypropylene is reaching its limits due to the rising demands of new wide band-gap semiconductors, especially in high-temperature applications

Classic high temperature alternatives to PP

Limited self-healing

Difficult to process

Expensive


New material blend for high temperatures

Blended film

Semi-crystalline PP

High temperatureoperation

Amorphous cyclicolefin copolymer (COC)*

Temperature limitation

Easy to processinto films

Not processableinto thin films

Processable into thin films down to 3 µm

Improved temperature operation

High temperatureoperation

* TOPAS® COC


Improved performance at high temperatures (1)

High mechanical stability Low specific leakage current

100

μA/μ

F

°C60

10

1140

High crystallineBOPP

COC-PP

140120110100 150 160

T (°C)

1.2

Shrin

kage

(%)

1

0.8

0.6

0.4

0.2

0130

Shrinkage in transverse direction Specific Leakage Current – 250 V/μm

130120110100908070

NEWNEW

High crystallineBOPP COC-PP


Frequency response of ESR

10010 10,000Frequency (kHz)

1.0

ESR

(Ohm

s)

0.10

0.01

80


COC-PP

0

PP+COC blends – T derating curve

1201009080 130 140T (°C)

200

Er (V

/μm

)

110

160

120

80


COC-PP

Improved performance at high temperatures (2)

Less derating Same ESR

● Aging and failure mechanism similar to BOPPBest of both worlds ● Similar self-healing properties

● Stable performance at up to 125 °C

NEW

NEW


Standard power capacitors have unfavorable ESR characteristics

15

ESR

[mΩ

]

Frequency [kHz]0

9

6

0100

12

150 300

Standard capacitor

3

50 200 250

ESR rises sharply with rising frequency


Standard power capacitors have unfavorable ESR characteristics

ESR rises sharply with rising frequency High ESR

1.6 W

3.6 W

15

ESR

[mΩ

]

Frequency [kHz]0

9

6

0100

12

150 300

Standard capacitor

3

50 200 250

Highpower losses


Root causes of increasing ESR

ESR ESLC

● Inhomogenous impedance and internal resonances

● Negative electromagnetic interaction

● Winding geometry and metal profile● Skin effect


Root causes of increasing ESR

Factors offering most potential for improvement!

Power capacitors must be fundamentally redesigned in order to operate reliably at higher frequencies

● Inhomogeneous impedance and internal resonances

● Negative electromagnetic interaction

● Winding geometry and metal profile● Skin effect

ESR ESLC


Standard capacitors are limited at high frequencies

Standard power capacitor Effects of inhomogeneous impedance and internal resonances

Standard capacitors are not ready for high frequencies

250

Cur

rent

shar

ing

(%)

Frequency [kHz]1

150

100

010

Top winding

50

100

200

Bottom winding


High ESR has thermal consequences

Cross-sectionOverall thermal map

5 kHz

2 kHz

Higher switching frequencies cause unbalanced thermal behavior

2Frequency [kHz]

60

Cur

rent

(Arm

s)

40

20

04 6 8 10 16 20 30 40 50

Frequency [kHz]

60

Cur

rent

(Arm

s)

40

20

020 25 40 5030 3510 155

Hot spotsin different

windings with 20 K difference

Max

Min

Max

Min

MinMin

MaxMax


Design of high-frequency capacitorsfocused on low ESR

15

ESR

[mΩ

]

Frequency [kHz]0

9

6

0100

12

150 300

Standard capacitor

High-frequency capacitorNew design must deliver

low and stable ESR across the critical frequency range

3

50 200 250


Design rules for high-frequency capacitors

Current must be homogeneously distributed at all frequencies

• Same impedance of all internal capacitive elements above, below and close to capacitor resonance frequency

• Avoid negative electromagnetic interactions between conductors (FEA electromagnetic software)

• Overlapped busbar from terminals to winding connection point is required in order to minimize the inductance


Makes snubber capacitors unnecessary in most cases

Optimized design enables lowest ESL

● Balanced phase switching loops● Same external dimensions and capacitance value● Same metallized film and capacitive elements ● Lighter weight copper strips● Significantly lower voltage overshoots

OLD DESIGN NEW DESIGN

12 nH6 nH


Introducing the new HF film capacitor series

700 V / 2300 µF to 2.2 kV / 370 µF

Frequency operation range up to 2 MHz

ESL of 10 nH with 2 terminals

High current density of up to 150 A/mF @ 700 V and 950 A/mF @ 2200 V

Operating temperature (without voltage derating) ● Standard polypropylene: +105 ºC● Advanced COC-PP dielectric: +125 ºC

(in development)

Compact dimensions (4 sizes):● 205 x 174 x 75 mm (l x h x w)● 205 x 174 x 100 mm● 210 x 126 x 70 mm● 210 x 126 x 95 mm

Resin-filled plastic case

EN 45545 HL2 R23 (fire and smoke)

Fully compatible with SiC and advanced Si semiconductors• High power density • Suitable for higher ambient

temperatures• Suitable for fast transients

(dV/dt) and ringing effects• Modular and suitable for

parallel connection• Snubber avoidance / low

voltage overshoot• Compact and lightweight,

enables lighter cooling system

NEW

ApplicationsTraction, industrial drives, renewable power


New capacitor designs enable stable thermal performance

Boundary conditions● Current: 130 Arms

● Frequency: 30 kHz● Ambient temperature: 30 ºC ● Power losses: 13.2 W

Advantages of new capacitor designs with a single winding

Homogenous temperature distribution

Max

Min

TC2

TC5

Max

Min

TC3 TC4

TC6

TC1

58.7 Max56.854.852.9514947.145.243.241.3 Min


New capacitor design enables linear ESR characteristics

New design features 80 percent lower AC losses at 100 kHz

80

Loss

es[W

]

Frequency [kHz]0

40

20

010 30 40 80

AC losses @100 Arms

60

20 50 60 70 90 100

-40%

Standard capacitor

High-frequency capacitor

-80%

Low ESRover the critical frequency range


New HF film capacitor series with extremely low voltage overshoot and ringing

Ready for hard switching

Ch2 Ch3 Ch4

Ch1

Math

500 V250 A

CH1CH3Math

CH2CH4

250 A250 A

M 200 ns Largeur Ext/10

1.00 kA 200 ns

Tek Exec. Decl. ?

M

1

Δ: 1.84kV@: 2.12 kV

Δ: 76.0kV@: 1.88 kV

Ch2 Max1.29kA

Ch3 Max1.19kA

Ch4 Max1.35kA

Ch1 Max2.90kV

22.2 kV/μs22.3 kV/μs

Math

Ch1 VDS MOSFET H3Ch2 I MOSFET H1Ch3 I MOSFET H2Ch4 I MOSFET H3

Math Total I MOSFETs H1+H2+H3

Ch1

Ch2 Ch3 Ch4A A A

V


Selected development projects with new HF film capacitors

Solar 1500 V power module(reference)● Infineon Easy 3B: IGBT + SiC MOSFET ● TDK DC link capacitors:

HF film + aluminum electrolytic

ALSTOM traction converter● 3.3-kV SiC MOSFET● New TDK HF film power capacitor

Traction power module (reference)● Mitsubishi LV100 3.3kV SiC MOSFET● New TDK HF film power capacitor ● Parallelization● Extension to Infineon XHP2

(1.7 kV and 3.3 kV): Ongoing


Future development focus

● New dielectrics for higher operation temperature

● Optimize entire DC link for high-frequency operation

● Applying design rules to PCB mounted capacitors

● Predict remaining lifetime according to real operation conditions● Improve reliability based on additional active and passive safety sensors…

ContinuousR&D

Further integration of busbar + capacitors

PCB mounted high-frequency solutions

Smart capacitorsable to provide

feedback to converter control systems

www.tdk-electronics.tdk.com

Documents

Innovative power capacitor technologies for wide band-gap ... · Innovative power capacitor technologies for wide band-gap semiconductors Advanced design features for high-frequency