Patent ID: 7346444

Claim:
A vehicle power unit capable of electrically controlling a brake of a vehicle having a battery as a power source of the vehicle, the vehicle power unit comprising: an auxiliary power source having a capacitor unit and used in abnormal conditions of the battery, the capacitor unit comprising a plurality of capacitor cells; a charge controller for charging the auxiliary power source from the battery; a voltage monitor for monitoring a voltage of the capacitor unit during charging; and a electronic controller for braking the vehicle by supplying power from the battery to the brake according to at least one of information from a brake pedal and information on a running state of the vehicle; wherein: the voltage monitor monitors whether the voltage of the entire capacitor unit exceeds a predetermined voltage, when the voltage monitor detects that the voltage exceeding the predetermined voltage is applied to the capacitor unit during charging, the voltage monitor determines an abnormality, and the charge controller stops charging, a voltage V 0 , which is the predetermined voltage that the voltage monitor determines as the abnormality, is calculated by the following Equation: V0 = V1 + 1 - ( F ⁢ ⁢ deg + A ⁢ ⁢ deg ) 1 + ( F ⁢ ⁢ deg + A ⁢ ⁢ deg ) × V1 × ( T - 1 ) wherein V 1 is a withstand voltage of each capacitor cell, Fdeg is an initial dispersion in the capacitor cells, Adeg is an aged deterioration of the capacitor cells, and T is the number of the capacitor cells connected in series.