Study on the impact of space charge on the lifetime of pulsed capacitors

As a key influence factor on the lifetime of pulsed capacitors, the repetitive frequency (f
_R
) of charge/discharge is studied in this paper based on the method of TSDC measurement. When f
_R
ranges from 0.1 Hz to 10 Hz, the lifetime of capacitors increases. The TSDC measurement is conducted, which is used to study the parameters of space charge induced by charge/discharge at various frequencies. The measurement result indicates that compared with capacitors which have experienced no charge/discharge, for capacitors that have experienced charge/discharge at 0.1, 1, 8 and 10 Hz for 3000 times, the trap density within the dielectric respectively increases by 66.1, 62.1, 54.8 and 31.5%. For pulsed capacitors which have experienced charge/discharge at 10 Hz, the peak current (I
_M
) is 22.2 pA, meanwhile, for pulsed capacitors which have experienced charge/discharge at 0.1 Hz, the I
_m
is 29.4 pA. For pulsed capacitors which have experienced charge/discharge at 10 Hz, the depth of deep traps is 0.94 eV, and the temperature corresponding to I
_m
is 97 °C, meanwhile, for pulsed capacitors which have experienced charge/discharge at 0.1 Hz, the depth of deep traps is 1.83 eV, and the temperature corresponding to I
_m
is 110°C. The parameters reflecting the characteristic of space charge can reasonably explain why the lifetime of capacitors tested at 10 Hz is three times of that at 0.1 Hz.