Experimental validation of active snubber circuit for direct AC/AC converters

Although direct ac/ac converters such as the Matrix converter have been in existence for a long time, scaling of these converters to higher voltage levels has not been addressed widely in the literature. Tremendous challenges in terms of device voltage sharing, safe commutation, and fault protection inhibit the application of these converters to high voltage applications such as dynamic grid control. The novel active snubber concept remedies this problem by placing a half-wave rectified envelope around every device, absorbing excess energy and ensuring proper voltage sharing. This paper examines a high frequency active snubber design for direct ac/ac converters. The performance of the snubber is analyzed at 13 kV / 1 MVA via simulations, and a proof-of-concept is implemented in a 10 kVA lab prototype.