Patent ID: 8724345

Claim:
A switching power source apparatus comprising: a first converter having a series circuit of a first switching element and a second switching element that is connected to both ends of a DC power source, a series circuit of a primary winding of a first transformer and a first capacitor that is connected to both ends of one of the first and second switching elements, and a first rectifier of a voltage generated by a secondary winding of the first transformer; a second converter having a series circuit of a third switching element and a fourth switching element that is connected to the both ends of the DC power source, a series circuit of a primary winding of a second transformer and a second capacitor that is connected to both ends of one of the third and fourth switching elements, and a second rectifier of a voltage generated by a secondary winding of the second transformer; a smoother of currents outputted from the first and second rectifiers; a pulse generator that outputs a first pulse signal according to a switching state of the first switching element and a second pulse signal according to a switching state of the second switching element; a first resonant series circuit of a first resonant reactor and a first resonant capacitor that receives the first pulse signal; a first controller configured to turn on/off the third switching element according to a current of the first resonant series circuit; a second resonant series circuit of a second resonant reactor and a second resonant capacitor that receives the second pulse signal; and a second controller configured to turn on/off the fourth switching element according to a current of the second resonant series circuit, wherein: the current of the first resonant series circuit to turn on/off the third switching element involves a 90-degree phase delay with respect to the first pulse signal and the current of the second resonant series circuit to turn on/off the fourth switching element involves a 90-degree phase delay with respect to the second pulse signal, so that the second converter operates with a 90-degree phase difference with respect to operation of the first converter; and the pulse generator includes a third transformer having first and second secondary windings to output the first and second pulse signals, respectively, according to a voltage that is applied to the third transformer and is synchronized with drive signals for the first and second switching elements.