Applying gate turn-off thyristors in regulated PFN charging

An off-line rectifier-capacitor system switched by a GTO (gate turn-off thyristor) and pulsed through a transformer has been used to charge a 20 kV system. The system has been designed to charge a 0.1 μF PFN (pulse forming network) to 20-24 kV with a range of input voltages which is as large as possible. Using an RC comparator circuit to choose the correct time to turn off the GTO, 0.3-0.5% voltage output regulation over an input voltage range of 30% has been achieved when charging a 0.1 ufd capacitor to 20 kV. The authors present modeling of the capacitor charge system, including efficiency and regulation estimates, experimental results, and numerical simulations of fault modes. Based on the experimental results demonstrated to date, this charging technique appears to offer a number of practical advantages in the moderate energy (0.1-100 J/pulse) range