| 摘要 |
A switching power-supply apparatus includes a first converter 3, a second converter 4, an output smoothing capacitor Co1, a series resonance circuit 1 and a control circuit 11. The first converter 3, in which switching elements Q11 and Q12 are connected to both ends of a direct-current power-supply Vin in series, and a capacitor Ci1 and a primary winding Np1 of a transformer T1 including an auxiliary winding Na1 are connected to both ends of the switching element Q12 in series, includes diodes D11 and D12 that rectify voltages generated in secondary windings Ns11 and Ns12 of the transformer T1. The second converter 4, in which switching elements Q21 and Q22 are connected to the both ends of the direct-current power-supply Vin in series, and a capacitor Ci12 and a primary winding Np2 of a transformer T2 are connected to both ends of the switching element Q22 in series, includes diodes D21 and D22 that rectify voltages generated in secondary windings Ns21 and Ns22 of the transformer T2. The output smoothing capacitor Co1 smoothes currents output from the diodes D11, D12, D21 and D22. The series resonance circuit 1 includes a resonance reactor L1 and a resonance capacitor C1 connected to the auxiliary winding Na1 in series. The control circuit 11 turns on/off the switching elements Q21 and Q22 according to a current flowing in the series resonance circuit 1. |
