Study on the lifetime characteristics of pulsed capacitors based on the theory of space charge

摘要

As a key influence factor on the lifetime of pulsed capacitors, the repetitive frequency (fR) of charge/discharge is studied in this paper based on the theory of space charge. A fact that in the absence of heat accumulation, from 0.1 to 10 Hz, the lifetime of capacitors increases with the fR is found. The measurement of space charge induced by charge/discharge at various frequencies is conducted. The measurement result indicates that the amount of space charge in capacitors experienced charge/discharge at 0.1 Hz is 29% higher than that of 10 Hz, which can reasonably explain why the lifetime of capacitors tested at 10 Hz is twice of that at 0.1Hz. Besides, a simplified TSDC is carried out to qualitatively measure the trap density of capacitors experienced lifetime tests, and found that the traps formed during charge/discharge tests at 0.1 Hz is more than 7x that of 10 Hz. The dielectric loss angle tangent (tanθ) of capacitors which have experienced charge/discharge at various frequencies is also tested, and from the tanθ tested at 0.001 Hz, (3.7 when fR is 0.1 Hz and 2.4 when fR is 10 Hz), it is revealed that the aging of pulsed capacitors can be slowed by enhancing the fR of charge/discharge, which matches well with the results of lifetime test.