Power supply system with multiple power sources in parallel

A power supply system with multiple power sources in parallel, comprising:

• a plurality of power supply devices, wherein an output terminal of each of the plurality of power supply devices is directly connected to a common supply line;
• wherein each of the plurality of power supply devices comprises:
• a DC-to-DC converter, transforming a first DC voltage into a second DC voltage;
• a transformer, comprising a first winding set and a second winding set, wherein the first winding set is coupled to the second DC voltage;
• a switching control device, comprising:
• a control unit, receiving a feedback voltage captured from the common supply line and producing an error signal;
• and
• a driving unit, receiving the error signal, segmenting the second DC voltage according to the error signal to produce a first AC voltage on the first winding set, and produce a second AC voltage on the second winding set;
• a rectifying device, receiving the second AC voltage and outputting a target DC voltage to the common supply line;
• and
• a judging device, receiving the feedback voltage, the error signal and the second AC voltage to determine whether the power supply device is normal.