Switching power supply device

A switching power supply device comprising:

• a plurality of half-bridge LLC converters each configured as a circuit element, each of the plurality of half-bridge LLC converters including:
• a first switch element and a second switch element connected in series between a positive electrode and a negative electrode of a DC power supply;
• and
• a resonant circuit including a resonant reactor having one end connected to a connection point between the first switch element and the second switch element, a primary winding of a transformer, and n+1 resonant capacitors comprising a zeroth order resonant capacitor to an nth order resonant capacitor, wherein n is a natural number equal to three or greater,
• wherein in each circuit element the zeroth order resonant capacitor has one end connected in series to the respective resonant reactor and the respective primary winding of the respective transformer, and another end connected to a respective power supply line, and
• wherein in each circuit element a kth order resonant capacitor of the n+1 resonant capacitors of each circuit element has one end connected in series to the respective resonant reactor and the respective primary winding of the respective transformer, and another end connected to another kth order resonant capacitor of one or more other circuit elements so that a k dimensional multiphase LLC converter having a phase difference of 360°/Pk is constructed by Pk circuit elements, wherein k is a natural number between one and n, and Pk is a natural number equal to or greater than one.