POWER SUPPLY DEVICE AND CONTROL METHOD FOR POWER SUPPLY DEVICE

A power supply device includes battery circuit modules , . . . each having a battery B, a first switching element S connected in parallel to the battery B, and a second switching element S connected in series to the battery B between the battery B and the first switching element S, the second switching element S being turned off when the first switching element S is turned on, a battery circuit module group in which the battery circuit modules , . . . are connected in series, and a control circuit for outputting, at intervals of a certain time, a gate signal for turning on and off the first switching element S and the second switching element S to the battery circuit modules