| 摘要 |
PROBLEM TO BE SOLVED: To output a voltage signal of a battery by insulation from a ground line of a battery pack while achieving simple and inexpensive circuit constitution, and to stably output the voltage signal of the battery for a long period of time. SOLUTION: A power supply device for vehicle detects a battery voltage of the battery pack 1 made by connecting a plurality of batteries 2 in series by a voltage detection circuit 3. The voltage detection circuit 3 includes: an isolation transformer 4 whose primary side is connected to a connection point 10 of the battery 2; a switching element 5 connected to the primary side of the isolation transformer 4; an insulation input circuit 7 on/off-switching the switching element 5; and a secondary voltage detection part 8 detecting an output voltage of the secondary side of the isolation transformer 4. The voltage detection circuit 3 connects the primary side of the isolation transformer 4 and a series input circuit 6 of the switching element 5 to a measurement point of the battery 2, on/off-switches the switching element 5 at a prescribed period by the insulation input circuit 7, and detects the output voltage of the secondary side of the isolation transformer 4 by the secondary voltage detection part 8 to detect the voltage of the measurement point. COPYRIGHT: (C)2008,JPO&INPIT
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