Ultrafast Static Transfer Switch with Resonant Turn-Off and Dynamic Inrush Restraint Capabilities for Data Center Power System Architecture

Data center applications require uninterrupted power supply capability to ensure continuous operation, which is realized by static transfer switch with multiple sources. Traditional static transfer switch has relatively slow transfer speed due to semi-controlled thyristor-based main switches. This paper presents a novel ultrafast static transfer switch with resonant turn-off capability for data center applications. There are two major contributions. First, a mixture switch based resonant turn-off circuit is proposed to accelerate the main thyristors turn-off speed thus reducing total transfer time between sources to milliseconds. Second, a flux-match based static transfer algorithm is deployed to limit the reconnecting dynamic inrush current induced by load side power distribution transformers, which alleviates the risk of overcurrent damage of the system. Working principles and design guidelines are demonstrated in detail. A three-phase 480V/1000A static transfer switch prototype is implemented. Continuous conduction experiment and resonant turn-off experiment are conducted respectively to validate the thermal and switching performances of the powertrain. System level transfer experiment is conducted at three-phase 480V/60A RMS to validate complete operation of the proposed static transfer switch.