A conversion circuit for supplying an output voltage after converting an input voltage, wherein the input voltage and the output voltage both comprise a first end and a second end, and the second end of the input voltage is connected to the second end of the output voltage, the conversion circuit comprising: a full-wave rectifier circuit comprising a first branch and a second branch connected in parallel between the first end and the second end of the output voltage, the first branch comprising a first secondary winding (Tr22) of a transformer (Tr) and a first rectifier switch (SR1) connected in series to form a first midpoint (m1), and the second branch comprising a second secondary winding (Tr21) of the transformer and a second rectifier switch (SR2) connected in series to form a second midpoint (m2); a first switch branch connected between the first end of the input voltage and the first midpoint (m1), and comprising a first switch (S1), a second switch (S2), a third switch (S3) and a fourth switch (S4) connected in series, wherein the first switch (S1) and the second switch (S2) are connected to form a first connection node (p1), the second switch (S2) and the third switch (S3) are connected to form a second connection node (p2), and the third switch (S3) and the fourth switch (S4) are connected to form a third connection node (p3); a first resonant unit electrically connected between the first connection node and a second midpoint; a second resonant unit electrically connected between the third connection node (p3) and the second midpoint (m2); a first primary winding (Tr1) of the transformer connected in series to the first resonant unit; and a first capacitor (C1) connected between the second connection node (p2) and the first midpoint (m1). a full-wave rectifier circuit comprising a first branch and a second branch connected in parallel between the first end and the second end of the output voltage, the first branch comprising a first secondary winding (Tr22) of a transformer (Tr) and a first rectifier switch (SR1) connected in series to form a first midpoint (m1), and the second branch comprising a second secondary winding (Tr21) of the transformer and a second rectifier switch (SR2) connected in series to form a second midpoint (m2); a first switch branch connected between the first end of the input voltage and the first midpoint (m1), and comprising a first switch (S1), a second switch (S2), a third switch (S3) and a fourth switch (S4) connected in series, wherein the first switch (S1) and the second switch (S2) are connected to form a first connection node (p1), the second switch (S2) and the third switch (S3) are connected to form a second connection node (p2), and the third switch (S3) and the fourth switch (S4) are connected to form a third connection node (p3); a first resonant unit electrically connected between the first connection node and a second midpoint; a second resonant unit electrically connected between the third connection node (p3) and the second midpoint (m2); a first primary winding (Tr1) of the transformer connected in series to the first resonant unit; and a first capacitor (C1) connected between the second connection node (p2) and the first midpoint (m1). <EOS>