MKP Power Capacitor Design Criteria
and Polypropylene Film Developments
Roberto Defant
Sales Area Manager
Capacitors & Systems
r.defant@ducatienergia.com
INTRODUCTION
Applications of MKP Power Capacitors
Renewables
Solar / Wind
•DC Link
•AC Output Filter
Transport
Industrial
EV / HEV
•DC Link
UPS Systems
•AC Input Filter
Rail
•Traction
•AUX Power
Motor Drives
•AC In/Out Filters
•DC Link
Welders
•AC Tuning
•DC Storage
INTRODUCTION
Why Metallised Film - Power Capacitors?
•Less Components – Simple Construction
•Low Power Losses
•Long Operating Life
•High Reliability – Low FIT Rate
INTRODUCTION
Metallised Film Comparison
PP
PET
PEN
PPS
650V/µm
550V/µm
500V/µm
450V/µm
+
−
−
++
++
−−
−−
+
Maximum Temperature
105°C
125°C
150°C
150°C
Self Healing Behaviour
++
O
−
−
Cost
++
+
−−
−−
Dielectric Strength
Temperature Stability
Dielectric Losses
Despite their relatively limited operating temperature range,
Metallised Polypropylene (MKP) Capacitors have become
the preferred solution for High Power Capacitors, due to the wide
voltage range available, very low losses and excellent cost
DIMENSIONING
Selection / Dimensioning of MKP Capacitors
Electrical Stress Determination
UAPP
UN-CAP
UN-CAP
V/µm
Assigned by each manufacturer basing
on its Metallisation and Winding
Technology as well as its chosen
Safety/Reliability Level
Capacitor Dimension – Form Factor
Thermal Resistance RTH
DIMENSIONING
Selection / Dimensioning of MKP Capacitors
Thermal Stress Determination – HotSpot Calculation
θHS = θC + RTH x (PD + PJ)
θC = Temperature of the Case
PD = Dielectric Losses; practically negligible for MKP Capacitors
PJ = Resistive Losses = Rs x IRMS2
DIMENSIONING
Ducati PPMd - Lifetime Graphs @ FIT 300
Lifetime hrs
1000000
100000
θ
HS =
10000
θ
θ
1,1
1,2
θH
θH
θH
HS =
=
S =5
=
S
S
9
80
70
6
10
0°
0°C
0
°C
°C
°C
C
0°
C
HS =
1000
0,8
0,9
1
1,3
1,4
1,5
1,6
Working Voltage / Rated Voltage U/Un
1,7
1,8
DIMENSIONING
Lifetime Calculation for Variable Operating States
For Variable Operating States, the Lifetime can be compounded
according to IEC 61709 (Electric Components – Reliability –
Reference conditions for failure rates and stress models
for conversion)
OUTLOOK
New Generation Converters’ demand to DC-Link Caps
•Higher Power Density = Higher Capacitor RMS Currents
•Higher Ambient/Case Temperatures in Operation
θHS = θC + RTH x (PD + PJ)
•Longer Lifetime / Lower FIT Rates
θHS
θMAX
OUTLOOK
Ducati developed a new high-crystallinity metallised PP Film
PP
PPMDH
PET
PEN
PPS
650V/µm
650V/µm
550V/µm
500V/µm
450V/µm
+
+
−
−
++
++
++
−−
−−
+
Maximum Temperature
105°C
125°C
125°C
150°C
150°C
Self Healing Behaviour
++
++
O
−
−
Cost
++
++
+
−−
−−
Dielectric Strength
Temperature Stability
Dielectric Losses
Ducati’s new PPMDH Metallised, High-Crystallinity Film
increases the Maximum Temperature of the film to 125°C.
PPMD: 100.000hrs at U/Un=1 and θHS=80°C
PPMDH: 100.000hrs at u/Un=1 and θHS=100°C
OUTLOOK
Advantages of Ducati PPMDH Film
For the same 100.000hrs Lifetime @ 300FIT
•+30°C θHS – respective to other manufacturers’ film
•+20°C θHS – respective to Ducati PPMD film
θHS = θC + RTH x (PD + PJ)
Longer Life / Lower FIT
Higher Case/Amb. Temp.
Higher RMS Current
No Reduction of typical PP Film Advantages
•Low Losses High Capacities / Powers
•Excellent Self-Healing Safety / Reliability
•Excellent Cost
APPLIABLE RANGE
C
20.000µF
DC86PS
DC86PS
DC86PS
2.000µF
DC86PS
200µF
DC89HC
20µF
DC82
DC86PS
1000V
2000V
3000V
4000V
5000V
6000V
Un
END
Thank You for Your Time
Roberto Defant
Sales Area Manager
Capacitors & Systems
r.defant@ducatienergia.com