The idea of a “solid-state transformer” has been discussed for
some time. Nearly 20 years ago, Navy researchers [2] proposed
a power-electronic transformer that consisted of an ac/ac buck
converter shown in Fig. 1 to reduce the input voltage to a lower
one. This was followed in 1995 by a similar EPRI sponsored
effort [3]. Both of these efforts yielded working prototypes, but
they operated at power and primary voltage levels that were orders
of magnitude below utility distribution levels.