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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 3
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 4
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 5
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 6
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 7
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 8
Frequency response of ESR
10010 10,000Frequency (kHz)
1.0
ESR
(Ohm
s)
0.10
0.01
80
High crystallineBOPP
COC-PP
0
PP+COC blends – T derating curve
1201009080 130 140T (°C)
200
Er (V
/μm
)
110
160
120
80
High crystallineBOPP
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 9
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 10
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 11
Root causes of increasing ESR
ESR ESLC
● Inhomogenous impedance and internal resonances
● Negative electromagnetic interaction
● Winding geometry and metal profile● Skin effect
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 12
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 13
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 14
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 15
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 16
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 17
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 18
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 19
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 20
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 21
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 22
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
Technologies & Products Press Conference 2019 Innovative power capacitor technologies for wide band-gap semiconductors © TDK Electronics 2019CC 10/19 23
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