Study on the Voltage Maintaining Performance of High Energy Density Capacitor

The high energy density (HED) capacitor is the energy storage component in capacitive pulsed power systems. There is an obvious voltage decay phenomenon, when the capacitor is disconnected from the power supply, and the higher the energy density is, the faster the voltage decays. And the voltage maintaining performance (VMP) of capacitor is of special interests especially in the occasion, which has high requirement of the output energy efficiency. For the HED capacitor made of metallized films, there are three factors affecting the VMP: self-healing, dielectric leakage, and polarization. In order to investigate the effect of above factors on the VMP of HED capacitor, the experiments and analysis of self-healing characteristics, dielectric leakage in stable status, and slow polarization are carried out. For a 4 kV/0.8 MJ/m
³
HED capacitor, the self-healing is responsible for 12.68% of the whole voltage decay, and the dielectric leakage contributes for 7.89% with the fact that the insulation resistance is in the range of 6.06 ×10
²
MΩ . Thus, the voltage decay is mainly caused by the slow polarization. Then a VMP simulation without considering self-healing process is established, and different working parameters such as charging time and holding time are studied by using the VMP simulation. When the charging time is 40, 13.3, and 1.3 s, the voltage decay in 60 s is 3.06%, 3.57%, and 3.85%, respectively, and when the holding time is 0, 10, 100, and 1000 s, the percentage of 60 s voltage decay is 3.06%, 2.71%, 1.23%, and 0.70%, respectively. The results based on the space charge reveal the facts that shorter charging time and holding time would result in faster voltage decay. With the consideration of the energy output efficiency and insulation voltage withstand capability, the charging time and holding time would be compromise values.