Comparison of Fast and Reliable Zero-Voltage Detection Topologies

In this article, three different topologies for a zero-voltage detection (ZVD) are introduced and compared. The ZVD is used to detect a zero-voltage condition (ZVC) across a medium-voltage (MV) switch. This switch can either consist of a single semiconductor device or several devices connected in series. Therefore, the ZVD must be able to withstand the same MV as the switch and at the same time be able to measure a low voltage (LV) across the switch with high reliability and accuracy. First, an emitter follower with an MV metal-oxide semiconductor field-effect transistor (
mosfet
) is introduced as the most trivial ZVD. Second, a current source with silicon carbide (SiC) Schottky barrier diodes to block the MV is introduced. Finally, an emitter-follower cascode using a silicon (Si) SiC super cascode of an LV
mosfet
and several junction field-effect transistors connected in series to block the MV is introduced. The second and third typologies can be scaled easily to any desired blocking voltage. For each topology prototype, test results are discussed. Their advantages and the corresponding measurement results as well as the application of the different topologies in a 5-MW dual-active bridge converter conclude this work.