Isolated Autonomous Capacitive Power Supplies to Trigger Floating Semiconductors in a Marx Generator

This paper reports the development of isolated autonomous capacitive power supplies to charge each drive circuit of the high voltage floating semiconductor stage in a solid-state Marx Generator. The circuit takes advantage of an auxiliary capacitor, charged in series with the main energy storage capacitor in each Marx generator stage, to supply the optic-fibre isolated gate drive circuit of the solid state switches. Laplace domain circuit analysis is made to determine the values of these capacitors and to obtain the desired voltages, with low ripple, for the required load. A laboratory prototype with three stages, 3 kW peak power, of this all silicon Marx generator circuit, with optic- fibre isolated triggering signals and autonomous capacitor isolated charging power supplies was built using 1200 V IGBTs and diodes, operating with 1000 V d-c input voltage and 10 kHz frequency, giving 3 kV and 10 μs pulse with, approximately, 15 V isolated autonomous power supplies in each stage.