| 摘要 |
PROBLEM TO BE SOLVED: To reduce conduction loss of a switching element configuring a power supply circuit.SOLUTION: A switching power supply circuit comprises: a series circuit composed of first, second, and third switching elements and a series circuit composed of fourth, fifth, and sixth switching elements, where the series circuits are connected in parallel between both terminals of input voltage; and a transformer having two primary side windings including one primary side winding connected between sources of the first and fourth switching elements and the other primary side winding of the two primary side windings, connected between sources of the second and fifth switching elements, where the winding direction of the latter is the reverse of the former. The first and third switching elements and the second switching element are made to be alternately on/off at 50% duty in a constant period; and the fourth and sixth switching elements and the fifth switching element are made to be alternately on/off at 50% duty in a constant period in a phase shifted from the on/off of the first and third switching elements and the second switching element. |
