Since 1980, great improvements have been made on DC filter capacitors using a combination ofmetallized plastic films and different segmentations of the metallization on those film dielectrics.Volume and weight have been reduced by a factor of 3 or 4 over the last years. Now filmmanufacturers have developed thinner films and have improved segmentation techniques used onthe metallization which has helped immensely in the improvement of such capacitors.Resulting from these strong developments, several families of products have been generated, byAVX starting from the smallest capacitance value to higher capacitance values as represented bythe AVX product families FFB, FFV3, FFVE, FFLI, FFLC.All these products are widely used by TPC customers due to the advantages that they offerUsing non-gas impregnated designs, the voltage ranges between 600VDC and 1200 VDC can bemore economically covered by film capacitors rather than electrolytic. Depending on theapplication, over 1200 VDC, vegetable oil-filled versions are recommended.Main advantages:§ High rms current capabilities, up to 1Arms per ??F§ Can withstanding surges up to 2 time the rated voltage§ Handle voltage reversal§ High peak current capabilities§ No acid inside§ Long lifetime§ No storage problemSecondly, with the strong semi-conductor evolution, requirements for DC link filters moved in away where stray inductance has to decrease dramatically in order to limit over-voltage due tosemi-conductor commutation.AVX, working very closely with its customers, has developed capacitors that can be directlymounted on to the new IGBT modules. These offer a major advantage in that the bus barbetween the IGBT module and capacitor is no longer required.
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