EPCOS, represented by Ramelec , has announced that its line of snubber capacitors for IGBTs has been considerably extended and now covers the voltage range from 850 to 2000V dc and the capacitance range from 47nF to 2.5µF.
The components are available with eight different strap terminals that are mechanically and geometrically compatible with most IGBT modules made by Eupec, Fuji, Semikron and Toshiba.
Up to five different terminals are available for each case variant. A specially devised cross-reference list enables customers to find the right capacitor with matching terminals quickly on the basis of the IGBT ordering code.
A polypropylene film metalised with aluminum and specified for the temperature range from –55 to +100°C is used as the dielectric. For higher capacitance values, up to four cylindrical windings in parallel are made per capacitor. The solder straps are welded in place.
Thanks to their compact and rugged design, the capacitors can also handle high currents. They can operate on up to 18A rms at 25°C /100kHz and withstand peak currents up to 1000A. Equivalent series resistance is less than 35 milliohm at 100kHz.
Switching pulses applied to insulated gate bipolar transistors (IGBTs) lead to voltage spikes that cause parasitic inductance in the link circuit. These transients limit maximum utilization of the voltage by the IGBT. The IGBT can be protected by connecting snubber capacitors.