Abstract
The increase in the involvement of renewable energy sources results in a high rate of semiconductor power converter applications. The power converters provide interconnections of DC microgrids with AC distribution lines. Inverters, which are connected directly to the grid lines, are exposed to the risk of overvoltage occurrence. This overvoltage can arise because of a grid malfunction or atmospheric phenomena, leading to damage to the semiconductor devices. The overvoltage protection is usually based on spark gaps, transient voltage suppression diodes, and combined with circuit breakers or crowbars. Spark gaps are very robust and simple devices, but not suitable for the end protections, because the breakdown voltage is relatively inaccurate. Suppression diodes are precise but not suitable for a higher portion of the transient wave energy. The crowbar protections are very robust, and their break voltage can be set very precisely, but the auxiliary power supply of the control circuit is usually needed for accurate control of break voltage. This paper introduces the crowbar overvoltage protection with a passive power supply. The goal of the proposed protection is the passive power supply, because all the control circuits operate directly on the converter DC link voltage.