Patent ID: 8803486

Claim:
A power supply device, comprising: a capacitor connected in parallel with a battery; two switching circuits connected in series with the capacitor; a pre-charge switching circuit connected in parallel with one of the two switching circuits; and a control unit that, when a voltage of the capacitor is lower than a voltage of the battery, controls the pre-charge switching circuit and at least one of the two switching circuits and performs pre-charging current limitation for the capacitor, wherein each of the two switching circuits connected in series with the capacitor and the pre-charge switching circuit comprises a single semiconductor switching element, or a plurality of semiconductor switching elements that are connected in parallel; wherein the capacitor is a hybrid capacitor doped with lithium ions; and wherein, during pre-charging current limitation, the control unit controls the semiconductor switching element of the pre-charge switching circuit stepwise, so as to cause pseudo increase of internal resistance of the hybrid capacitor.