A　circuit　configuration　and　a　circuit　topological　family　of　step-up　ac　voltage　regulators　with　high-frequency　link　are　proposed.　This　kind　of　circuit　topology　is　composed　of　input　LC　filter,　energy-storage　inductor,　input　cycloconverter,　high-frequency　transformer,　output　cycloconverter　and　output　filtering　capacitor.　The　regulators　can　convert　an　unstable　sinusoidal　voltage　with　high　THD　to　a　stable　sinusoidal　voltage　with　the　same　frequency　and　low　distortion.　Operating　principle,　normalized　output　characteristics,　phase-shifting　control　strategy,　methods　to　suppress　magnetic　saturation　of　the　energy-storage　inductor　at　start-up,　and　voltage　spike　caused　by　the　high-frequency　HF　transformer　leakage　inductance　are　proposed　and　fully　investigated.　The　results　from　theoretical　analysis　and　principle　experiment　indicate　that　the　proposed　regulators　have　advantages　of　high-frequency　galvanic　isolation,　simple　topology,　two-stage　power　conversions,　bidirectional　power　flow,　high　conversion　efficiency,　and　high　reliability　during　short-circuit　conditions　of　the　load.