| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem that in a switching power-supply device having a conventional series resonant converter (LLC), constant-current characteristics at a low voltage and a low current for preliminary charging is not achieved when the series resonant converter is set to an LC resonant constant satisfying normal charging.SOLUTION: A switching power-supply device 20 includes: an LLC 40 receiving DC power and in which a storage battery 21 is connected to an output side; a preliminary charge determination circuit 60 detecting an inter-terminal voltage value Vbatt of the storage battery 21, determining whether preliminary charging for the storage battery 21 is needed from the detection result, and outputting a main circuit cut-off signal S60 when the preliminary charging is needed from the determination result; a cut-off circuit 70 cutting off an output of a main circuit of the LLC 40 when the main circuit cut-off signal S60 is inputted; and a winding circuit 50 connected in parallel to an output side of the LLC 40. For this reason, constant-current characteristics at a low voltage and a low current for preliminary charging can be achieved when the LLC is set to be an LC resonant constant satisfying normal charging. |
