Basic Experiments With a Superconducting Full-Bridge Current-Driven Inverter

Superconductors have a highly nonlinear current voltage curve that is already used in various applications, such as, for example, in fault current limiters, flux pumps, and persistent mode magnets. It is already known that the dynamic resistance of superconductors can be switched <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">on</small> and <sc xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">off</small> with external magnetic fields. This article applies this knowledge and demonstrates for the first-time experiments with a full-bridge inverter that uses the dynamic resistance of high-temperature superconductors triggered by external magnetic fields as switching elements. For a basic experimental setup, the influence of magnetic field, frequency, and superconductor properties on the behavior of the inverter was investigated. As a result, the principle of a full-bridge current-driven inverter using the dynamic resistance of superconductors and operating in short-circuit output condition is experimentally demonstrated. It is shown that, with reference to the considered short-circuit operation, commutation times down to 5 ms were achieved and that a further reduction is possible by increasing the superconductor length that is exposed to magnetic fields. Long operation times of up to 120 s have been achieved. An upscaling towards faster switching times and higher voltages are possible by further increasing superconductor length.