INDUCTIVE HIGH VOLTAGE PULSE GENERATOR BASED ON RESONANCE SYSTEM
Adam Lindblom - Jan Isberg - Hans Bernhoff - Mats Leijon
A high voltage pulse generator based on inductive intermediate energy storage has been constructed. The current switching technique used in the generator is based on a resonance system. Opening switches for high currents are generally difficult to construct and the switch used here has proven to turn off 1.8 kA DC-current at a rate of 300 A/μs. The generator is equipped with a step-up transmission line transformer as intermediate magnetic energy storage and the primary and secondary energy storages are capacitive. An LC-resonance circuit is combined with 3 vacuum interrupters in series as an opening switch on the primary side of the transformer. Discharging the capacitor bank into the primary winding of the transformer introduces a 200 Hz sinusoidal oscillation on the primary current. The movable contacts in the vacuum interrupters are operated mechanically and stable arcs are formed as the gaps are opened. As the 200 Hz sinusoidal current reaches its first maximum, the small LC-resonance circuit is triggered and the current achieves a new frequency of 25 kHz. The large amplitude and high frequency generated by the LC-resonance circuit results in a zero crossing of the primary current. As the current crosses zero the arc deionises and the current is switched off. Pulse shaping with a 2 x 50 m Blumlein configuration on the secondary side of the transformer has been investigated. A rise-time of 40 ns and pulse duration of 700 ns were measured for a resistive load. The aim with this pulse generator is to get familiar with the challenges involved in scaling the system to higher performance.
Keywords: high voltage, pulsed power, transformer, transmission line, vacuum interrupter, current switch