| 摘要 |
PROBLEM TO BE SOLVED: To provide a switching power supply device capable of achieving higher efficiency than conventional ones and having a less number of components.SOLUTION: A switching power supply device 1 includes: a first serially-connected body 2 connecting switching elements Q1, Q2 via a middle point P1; a second serially-connected body 3 connecting switching elements Q3, Q4 via a middle point P2; a capacitor C3 for improvement of power factor, connected in parallel to the serially-connected bodies 2, 3; a transformer T of which a primary coil T1 is connected to between the middle points P1, P2; a secondary side circuit 5 for rectifying and smoothing a voltage induced on secondary coils T2a, T2b of the transformer T; an inductor L1 having one end connected to the middle point P1; a capacitor C1 having one end connected to the other end of the inductor L1; and a control section 6 for controlling the switching elements Q1 to Q4 on the basis of a polarity of the voltage at the other end of the capacitor C1 with the middle point P2 as reference. An AC power source E may be connected to between the other end of the capacitor C1 and the middle point P2.SELECTED DRAWING: Figure 1 |
