High performance, high-power capacitor charging: Focus on pulse-to-pulse repeatability

Pulse-to-pulse repeatability (PPR) is an important parameter in capacitor charging applications. This paper studies the subject both theoretically and experimentally using as a platform a novel low-cost, high performance 20-kJ/s, 10-kV, 1-kHz repetition-rate charger based on an energy-dosing converter topology. It is stated that PPR is affected by quality of the HV measurement and depends on the ratio of the energy stored in the HV transformer magnetic system, its parasitic capacitance, etc., to that stored in the load capacitor. The influence of the second factor is studied. It came clear that empiric formulae usually used in literature are too simplistic to account for the complex electromagnetic processes; they may yield overstated values. The theoretical findings are compared with both PSpice simulations and experimental results. Both PSpice simulations and analytical tools predicted pulse-to-pulse repeatability of ±0.15 %; the measured figures are ±0.4 % and ±0.5 % for short- and long-term operation, respectively, at peak charging and repetition rates.