Patent ID: 7868567

Claim:
A booster converter circuit for a vehicle comprising: a battery that outputs a DC voltage; a switching unit having a switching element to be controlled to ON or OFF; an inductive element unit being connected between the battery and the switching unit and including an inductive element; an output voltage measuring unit that measures an output voltage of the booster converter circuit for a vehicle; a current measuring unit that measures a converter current flowing through a path from the battery to the switching unit; and a switching control unit that controls the switching element, the switching control unit including: a duty ratio determining device that obtains a duty ratio when controlling the switching element; and a switching element controlling device that controls the switching element at the duty ratio obtained by the duty ratio determining device, causing the inductive element to generate an induced electromotive force by the control of the switching element, such that the booster converter circuit outputs a voltage obtained by adding the induced electromotive force to an output voltage of the battery and supplies electrical power to a motor for driving a vehicle using the outputted voltage, wherein the duty ratio determining device includes a duty ratio calculating device that obtains a new duty ratio on the basis of a duty ratio obtained previously and the measured output voltage value at the time when the duty ratio obtained previously was obtained, when a measured converter current value at the time of obtaining a new duty ratio exceeds a predetermined current threshold, and wherein the duty ratio determining device obtains a new duty ratio so that a value of the converter current falls within a predetermined range.