K-LEM KEMET Life Expectancy Model

Vincenzo Emanuele Caridà

K-LEM Developer Engineer

©KEMET Corporation. All Rights Reserved. 2

Vincenzo Emanuele Caridà

R&D New Product Engineer FILM BUSINESS UNIT SASSO MARCONI (BO) ITALY

Master Degree in Electrical Engineering - Bologna University in December ’17

Employed in KEMET in January ’18

Content

1. Introduction a) What is K-LEM b) Key Applications and Environmental Examples c) Film Capacitor Constructiond) Key Factors of Capacitance Degradation in Film Technology

2. K-LEM Features – Easy to Design-In

3. K-LEM Tool Development Processa) Boundaries Conditions and Testingb) Data Analysisc) Model Regressiond) Evaluation and Implementation

4. Film Capacitor Series available in K-LEM

What is K-LEM

K-LEM (KEMET Life Expectancy Model) is a powerful design tool, able to predictthe service life of KEMET Metallized Film Capacitors designed to withstand HarshEnvironmental conditions

It is the first tool in industry World, able to take into consideration three key factorsin the life of a capacitor: Temperature, Relative Humidity and Bias Voltage (THB)effects. It is based on a model developed at KEMET Corporation

The K-LEM (BETA V1.0) is available as a Film Life Calculator at our KEMETEngineering Center Web Site, and its full version will be part of our future DesignPlatform, K-SIM 3.0

Capacitor Life Expectancy

Product Lifetime Estimation is a Critical Design Factor for Different Applications and Enviromental Conditions

Applications Environments

K-LEM helps to reduce unscheduled downtimesand service costs

Data Source: Moore, L.M. and H.N. Post, « Five years of operating experience at a large, utility-scale photovoltic generating palnt», Progress in Photovoltaics: Research and Applications

InverterTop Four Failures

Sub-SystemInverter

PV System

UnscheduledMaintenance

37% of Power Down Time

Loose Connection of Input and output connectors

Wear-out of theCapacitor Bank

54% of Service Cost

Varistor failure-short from the surge

Degradation of MosFET”s and diodes

Single-sided Metallized Polypropylene Film

OneSection

TwoSections

Film Capacitor basic construction concepts

𝑪𝑪 = 𝜺𝜺𝟎𝟎𝜺𝜺𝒓𝒓𝑨𝑨𝒅𝒅

Self Healing

PartialDischarge

ElectrochemicalCorrosion

Self-Heating VAC & IAC50/60 Hz

ΔC/C negligible during normal application

(<< 1%)

ΔC/C occurs mainly at Low Temperature and Harsh Environment

Condition

ΔC/C is Proportional to Temperature,

Relative Humidity and Bias Voltage

ΔC/C and Lifetimeare Impacted by

Self-Heating

Capacitance Drop and Lifetime impacting factorsin Polypropylene Film Capacitors

K-LEM Considers The Three Main Capacitance Drop Causes

Film Capacitor Self Healing Property

Source: Maawad Makdessi, et al., «Metallized polymer film capacitors ageing law based on capacitance degradation”, Microelectronics Reliability, 2014

DefectMetallization

Dielectric Film

LocalizedBreakdown

Clearing of the Defected Zone

Metal VaporChemical By-Products

Partial Discharge (PD)

Source: Yasmin Hanum Md Thayoob, et al., “Characterization of Phase Resolved Partial Discharge waveforms from instrument transformer using statistical signal processing technique”,IEEE International Conference on Signal and Image Processing Applications (ICSIPA), 2015

Electrochemical Corrosion

Metallization

Applied AC voltage

Air Gap Induced VoltageZn° → Zn2+ + 2 e-

2 H2O + 2 e- → H2 + 2 OH-

Metallization 2

P P D i e l e c t r i c

P P D i e l e c t r i c

Metallization 1

Air Gap

Self-Heating

∆𝑻𝑻𝑴𝑴𝑴𝑴𝑴𝑴= �𝒊𝒊=𝟏𝟏

𝟏𝟏=𝑵𝑵𝑰𝑰𝒓𝒓𝑰𝑰𝑰𝑰𝒊𝒊𝟐𝟐

𝟐𝟐𝝅𝝅𝒇𝒇𝒊𝒊𝑪𝑪× 𝒕𝒕𝒕𝒕𝒕𝒕𝑰𝑰𝑴𝑴𝑴𝑴(𝒇𝒇𝒊𝒊) × 𝑹𝑹𝒕𝒕𝒕𝒕

K-LEM Features

INPUT

Application Profiles

Temperature (°C)Relative Humidity (%)

AC Voltage (V)

OUTPUT

Operational Expected Life

Hours & YearsEnd of Life

Criteria (ΔC/C: -20 %)

Easy To Design-in Tool

3 ) M o d e l R e g r e s s i o n

4 ) R e g r e s s i o n C o n d i t i o n C h e c k i n g

1 ) B o u n d a r i e s C o n d i t i o n &

E l e c t r i c a l Te s t i n g

2 ) D a t a A n a l y s i s & M o d e l

D e f i n i t i o nK-LEM

Implementation of K-LEM Application

1) Boundaries Conditions & Electrical Testing

Boundaries Conditions Electrical Testing

• Definition of failure with end of life criteria of the capacitors

• Reliability Level %

• Confidence Level %

• Stress Conditions

• Characterization of the capacitors under test

• Observing the same failure mechanism

• Improve the Model Regression

• Extended tests for accurate data (>1 year)

2) Data Analysis & Model Definition

Failure Mechanisms & Measured Variables

ΔC/C % ΔTg δ IR

-15-14-13-12-11-10-9-8-7-6-5-4-3-2-101

0 200 400 600 800 1000 1200 1400 1600 1800 2000

dC/C

[%]

Time [h]

Capacitance Trend Vs. Time for Different THB TESTSAMPLE #1

SAMPLE #2

SAMPLE #3

SAMPLE #4

SAMPLE #5

SAMPLE #6

SAMPLE #7

LIM

2) Data Analysis & Model Definition

To calculate the estimated life in real working condition, based on performances measured on reference test condition

85°C / 85% R.H. at Vrated.

REFERENCE CONDITION

WORKING CONDITION Ro

𝑹𝑹𝑲𝑲 = 𝒇𝒇 𝑻𝑻 ∗ 𝒕𝒕 𝑹𝑹.𝑯𝑯. ∗ 𝒕𝒕(𝑽𝑽)

The KEMET Functions f(T), g(R.H.), h(V) are based on a tuneable formula for different capacitors and through several parameters to fit as close as possible the model regression.

The Life Model Produces a Ratio Factor

R0

The KEMET Model Estimates the Calculated Ratio

Rk

3) Model Regression

𝑅𝑅𝑂𝑂 ≈ 𝑎𝑎 + 𝑏𝑏 � 𝑅𝑅𝐾𝐾b: regression slope a: regression intercept

FACTOR Ro

REFERENCE CONDITION

WORKING CONDITION

FACTOR Rk

REFERENCE CONDITION

WORKING CONDITION

KEMET THB Model Experimental Data

4) Model Performance

1050-5

99

95

90

807060504030

20

10

5

1

Residual

Perce

nt

Normal Probability Plot(response is Ro)

7,55,02,50,0-2,5-5,0

7

6

5

4

3

2

1

0

Residual

Frequ

ency

Histogram(response is Ro)

K-LEM Regression, Ro = 0.366 + 0.9955 * Rk

9080706050403020100

90

80

70

60

50

40

30

20

10

0

S 3,38830R-Sq 99,1%R-Sq(adj) 99,0%

Rk

Ro

Residual Plots for Ro

1050-5

99

95

90

807060504030

20

10

5

1

Residual

Perc

ent

Normal Probability Plot(response is Ro)

7,55,02,50,0-2,5-5,0

7

6

5

4

3

2

1

0

Residual

Freq

uenc

y

Histogram(response is Ro)

4) Model Performance

• Coefficient of determination: Rsq > 90 %

• Linearity: b ≈1

• Residual Standard Deviation: S<4

• Confidence Level = 95%

• Residual Normally Distributed

Probability Plot of Residual. Normal; 95% of CI

1050-5-10

99

95

90

807060504030

20

10

5

1

Mean -0,06727StDev 2,858N 11AD 0,588P-Value 0,096

RESIDUAL

Perc

ent

1 10 20 30 40 50 60 70 80 90 100 110

010,00020,00030,00040,00050,00060,00070,00080,00090,000100,000110,000120,000130,000140,000150,000

17.5

1522.5

3037.5

4552.5

6067.5

7582.5

9097.5

Temperature [°C]

Rela

tive

Hum

idity

[%]

140,000-150,000

130,000-140,000

120,000-130,000

110,000-120,000

100,000-110,000

90,000-100,000

80,000-90,000

70,000-80,000

60,000-70,000

50,000-60,000

40,000-50,000

30,000-40,000

20,000-30,000

10,000-20,000

0-10,000

4) Real Case: F862 X2 EMI Capacitor 310 VAC

Lifetime Expectancy (hrs.) @ 240 Vac

F862FY475310K-V054

4) Real Case: F862 X2 EMI CapacitorLifetime Expectancy at Two Voltages

Lifetime Expectancy (hrs.)

1

10

20

30

40

50

60

70

80

90

100

11017.51522.53037.54552.56067.57582.59097.5

Temperature [°C]

Relative Humidity [%]

240Vac

1102030405060708090100110

17.51522.53037.54552.56067.57582.59097.5

Temperature [°C]

Relative Humidity [%]

310 Vac

K-LEM WEB TOOLFILM Capacitor Series Available in K-LEM Tool

F862-V054X2

EMI Suppression

310 Vac

According with Grade IIB

AEC-Q200

F863X2

EMISuppression

310 Vac

85 °C / 85 R.H. 500Hrs

@ 240 Vac

AEC-Q200

R41TX1/ Y2

EMI Suppression

300 Vac125 ºC

According withGrade IIIB

AEC-Q200

K-LEM Application In KEMET Engineering Center Web Site

K-LEM available on KEMET Design Platform, K-SIM 3.0

EMI Suppressors

X & Y Safety

Capacitors

THB High Capabilities

AC & DC Power Box

DC-Link &

AC Filter

THBHigh Capabilities

K-LEM WEB TOOLK-LEM Web Tool For Future THB Film Series

All the coming Film Series with Temperature, Humidity Bias (THB)

capability will be available on K-LEM Model