A　circuit　configuration　and　circuit　topological　family　of　Buck　mode　AC/AC　converters　with　high　frequency　link,　and　uni-polarity　phase-shifted　control　strategy　are　proposed　and　deeply　investigated.　This　kind　of　converters　is　constituted　of　input　cycloconveter,　high　frequency　transformer,　output　cycloconverter,　input　and　output　Alters,　and　can　transfer　an　unsteady　ac　voltage　with　high　harmonic　into　steady　same　frequency　ac　sinusoidal　voltage　with　low　harmonic.　By　using　uni-polarity　phase-shifted　control　strategy,　output　filtering　inductance　current　are　naturally　commutated,　and　ZVS　of　the　output　cycloconverter　are　realized.　The　converters＇　averaging　model,　the　output　characteristic　curve,　and　design　criteria　for　the　key　circuit　parameters　are　given.　The　theoretical　analysis　and　test　result　of　1kVA　220V±10%50HzAC/　110V50HzAC　prototype　have　shown　that　the　converters　have　the　advantages　such　as　high　frequency　electrical　isolation,　simple　topology,　two-stage　power　conversion(LFAC/HFAC/LFAC),　bi-directional　power　flow,　uni-polarity　SPWM　waveform,　high　efficiency,　high　power　density,　high　steady　precision,　low　THD　of　the　output　voltage,　strong　adaptability　to　various　loads,　high　line　power　factor　and　low　audio　noise　etc.　©2007　IEEE.