EPCOS Extends Snubber Series for IGBTs

EPCOS AG (Germany) announced that its line of snubber capacitors for insulated gate bipolar transistors (IGBTs) has been considerably extended and now covers the voltage range from 850 Vdc to 2,000 Vdc, and the capacitance range from 47 nF to 2.5 µF. 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 metallized with aluminum and specified for the temperature range from –55 °C 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. The capacitors can also handle high currents. They can operate on up to 18 A rms at 25 °C/100 kHz and withstand peak currents up to 1,000 A.

Equivalent series resistance is less than 35 milliohms at 100 kHz. Switching pulses applied to IGBTs lead to voltage spikes that cause parasitic inductance in the link circuit. The transients limit maximum utilization of the voltage by the IGBT. The IGBT can be protected by connecting snubber capacitors.