Interfacing transformer for a pulsed load current exceeding 1 MA

Abstract

In much pulsed power experimentation a capacitor bank is discharged into an inductive load, but although sufficient energy may be available in the capacitors their voltage rating may considerably exceed that necessary for the load and the current delivered during the experiment may accordingly be too low. This paper describes a novel design of air-cored transformer that has been used as an interfacing or matching device in such a situation, where peak load currents between 1 and 2 MA were required.Design considerations led to the use of an air-cored autotransformer connection wound with copper sheet conductors. Although thick wide conductors and clamping are needed to prevent deformation due to high magnetic pressure, the transformer is nevertheless relatively simple, easy to make, lightweight and inexpensive.This paper describes the design and the winding arrangement of the transformer that was constructed, and presents typical experimental results.

Fast and accurate two-dimensional modelling of high-current, high-voltage air-cored transformers

“…LI 2 /2). The self-inductance of the single-turn primary winding then is given by 2 and that of the multi-turn secondary winding (represented by N concentric cylinders) by…”

“…This paper explains techniques that have been developed at Loughborough for the fast and accurate design of step-up air-cored HVTs. The approach described can also be exploited in transformers with quite different geometries, such as highcurrent impedance-matching transformers [2] and the Tesla transformers used in electron beam accelerators and compact repetitive microwave power sources [3,4].…”

“…Such a simplistic approach cannot, however, accurately describe the complex current distribution resulting from magnetic diffusion within the conductors. For example, in spiral-strip transformers for highcurrent impedance matching [2], the current distribution will show axial end effects as well as pronounced proximity effects if the windings are thick.…”