In　this　paper,　the　circuit　topology　of　single-stage　isolated　charging/discharging　DC-AC　converter　with　second　harmonic　current　suppression　is　proposed.　Based　on　which　an　analogous-rectifying　unipolar　phase-shifted　control　strategy　with　constant　charging/discharging　current　is　also　proposed,　which　rectifies　the　Sinusoidal　Pulse　Width　and　Position　Modulation(SPWPM)　wave　of　high-frequency(HF)　transformer　to　positive/negative　half　line　cycle　Sinusoidal　Pulse　Width　Modulation(SPWM)　wave　through　the　bi-directional　rectification　circuit,　and　realizes　constant　charging/discharging　current　of　the　battery　at　the　same　time.　Aiming　to　suppress　the　input　second　harmonic　current,　an　L-r-C-r　parallel-resonant　circuit　which　is　connected　in　series　between　the　battery　and　input　filter　capacitor　is　introduced.　Experimental　results　of　the　designed　prototype　show　that　the　proposed　converter　has　excellent　performances　such　as　HF　galvanic　isolation,　single-stage　bi-directional　charge/discharge,　high　conversion　efficiency　and　small　ripple　of　input　current,　which　provides　a　new　methodology　for　battery　charge/discharge　in　distributed　generation　systems.