Ultra-High-Voltage (7-kV) Bidirectional Flyback Converter Used to Drive Capacitive Actuators

Abstract

Dielectric elastomer actuators (DEAs) have extremely advantageous characteristics such as lightness, compactness, flexibility, and large displacements. However, in order to operate, they can require voltages in the order of several thousands of volts. Thus, to unleash the full potential of DEAs, it becomes essential to be able to generate and manipulate such voltages with an electronics as compact and efficient as possible. While previous works showed that it was possible to implement a system capable of supplying voltages of up to 2.5 kV and recovering part of the energy stored in DEAs (due to their capacitive nature), no work managed to go over that threshold for two main reasons: first, due to the absence of switches capable of withstanding more than 4.5 kV, and, second, due to parasitic capacitances of the flyback's coupled inductor, which steal an increasingly large part of the energy destined for the load when the output voltage is higher. This article, therefore, proposes a global design, where the factors limiting the increase in the output voltage have been mastered. Through a careful design of the coupled inductor combined with the use of mosfets put in series, thanks to the pulsed transformer gate drive topology to handle the high voltages, this work goes beyond the current state of the art. Indeed, here, we present various strategies undertaken, which led to the manufacture of a bidirectional flyback converter capable of amplifying an input voltage of 12 V to more than 7 kV across a capacitive load and recuperating parts of the energy stored. A preliminary study of the efficiency shows an approximate 58% efficiency during the charge phase from 0 V to 7 kV and a 54% efficiency during the discharge phase.