Active AC snubber for direct AC/AC power converters

While direct AC/AC converters like matrix converters have been around for a while, their applications are generally limited to low voltages due to complexity and issues in scaling to high voltages, including inadequate fault tolerance, complex switching patterns where errors can lead to device failures, and complex gate drive requirements for voltage sharing among the devices. For these reasons, voltage source inverters (VSI)-based topologies remain the de facto standard in medium to high voltage power conversion applications. This paper will propose an actively-controlled AC snubber concept that addresses the scalability issues with direct AC and AC/AC converters. The paper will use the previously proposed single-phase direct AC topology known as the dynamic capacitor (D-CAP) to demonstrate the operation of the AC snubber. However, the proposed snubber concept is equally valid for any topologies employing series-connected devices to scale up to higher voltages.