Power conversion device and controlling method thereof

A controlling method of a power conversion device, the power conversion device comprising a power supplying terminal, a switching converter, a signal injector, a coupler circuit, a detecting circuit and a controller, the power supplying terminal being detachably connected with a load, the switching converter being electrically connected with the power supplying terminal and comprising at least one switch element, a first end of the coupler circuit being electrically connected with the signal injector, a second end of the coupler circuit being electrically connected with the power supplying terminal, the detecting circuit being electrically connected with the first end of the coupler circuit, the controller being electrically connected with the detecting circuit and the at least one switch element, the controlling method comprising steps of:

• (a) activating the power conversion device;
• (b) allowing the signal injector to provide a signal;
• (c) transmitting the signal to the power supplying terminal through the coupler circuit, wherein depending on whether the load is connected with the power supplying terminal or disconnected from the power supplying terminal, an operating parameter at the first end of the coupler circuit has a first variation value or a second variation value in response to the signal;
• (d) the detecting circuit detecting whether the operating parameter at the first end of the coupler circuit has the first variation value or the second variation value;
• and
• (e) the controller selectively enabling or disabling a switching action of the at least one switch element according to a detecting result of the detecting circuit, wherein when the switching action of the at least one switch element is enabled, an input voltage is converted into an output voltage by the switching converter and the output voltage is outputted to the load through the power supplying terminal;
• wherein the coupler circuit comprises:
• a transformer, wherein a primary winding assembly of the transformer is electrically connected with the signal injector for receiving the signal, and the primary winding assembly of the transformer is served as the first end of the coupler circuit;
• and
• a capacitor having a first end electrically connected with a secondary winding assembly of the transformer and a second end electrically connected with the power supplying terminal, wherein the second end of the capacitor is served as the second end of the coupler circuit.