High frequency series resonant DC link power conversion

An AC/DC conversion scheme is presented which eliminates the need for self-commutated devices and requires only 12 thyristors for full double bridge AC to AC power conversion. The system utilizes a series resonant DC link between the AC/DC and DC/AC converters. This series resonant scheme is, in effect, the dual of the parallel DC resonant converter. The DC resonant circuit can be essentially considered as a commutating circuit which ensures turn-off of all twelve thyristors by providing the necessary zero-current instants. A significantly improved sinusoidal current waveform can be obtained at both the input and output compared to conventional high-power converters by the use of high-frequency pulse density modulation.<>