Design and implementation of DC-to-DC converter topology for current regulated lightning generator.

When aircraft are impacted by lightning strikes, structural fuselage and components are stressed by electric and thermo-mechanical constraints which impose a need for reliable experimental test benches to design accurate and enhanced lightning protections. The aim of this work is to investigate, design, and compare different topologies of DC high-current generators in order to experimentally reproduce the continuous lightning current waveform component applied to produce an electric arc up to 1 m long. An electrical model of a standard lightning C*-waveform for a 1 m long arc is set, leading to an equivalent resistor varying from 4 to 8 Ω. This model enables a theoretical comparison between the DC/DC converters' Buck and Buck-boost topologies to generate such a current-regulated waveform through a load using a capacitor bank and applying a minimum initial stored energy criterion. The experimental implementations of Buck and Buck-boost configurations are designed and tested. Optimizations about the accuracy of the current regulation through the feedback loop and the respect of components' operating electrical and power parameters are presented. In particular, the implementation of a snubber filter and a frequency control of the switching operations, which are mandatory elements in the operation of DC converters, are described to prevent the circuit from damaging initiated by transient overvoltage peaks. Both Buck and Buck-boost configurations are experimentally implemented to generate a standard C* waveform through a 4 Ω resistor and the Buck configuration proves the ability to generate electric arcs up to 1.5 m respecting the standard aeronautic waveform of lightning.