An isolated power converter can include: a primary side having a primary winding and a primary power transistor; a secondary side having a secondary winding and a secondary power transistor; a secondary control circuit configured to change a voltage across the secondary winding to change a voltage across the primary winding during a period when both the primary power transistor and the secondary power transistor are in a turn-off state; and a primary control circuit configured to control switching states of the primary power transistor, such that an output signal of the isolated power converter matches an output demand.