Patent ID: 7868584
Filing Date: 2011-01-11
Classification: B60L,H02J,H02M,Y02T

Abstract:
1. A DC-DC converter operative to convert a voltage of an input power source connected to an input terminal thereof and charging a secondary battery connected to an output terminal thereof, comprising: a synchronous rectification circuit including a rectifier-side synchronous rectifier element and a commutator-side synchronous rectifier element; an inductor configured to store electric energy when the rectifier-side synchronous rectifier element is in an ON state and the commutator-side synchronous rectifier element is in an OFF state and to release stored electric energy when the rectifier-side synchronous rectifier element is in the OFF state and the commutator-side synchronous rectifier element is in the ON state; a capacitor configured to smooth a voltage rectified by the synchronous rectification circuit; an output voltage detection circuit configured to detect an output voltage of the output terminal; and a characteristic evaluating unit arranged to pass a current through a closed loop including the commutator-side synchronous rectifier element, the inductor, and the secondary battery by turning on the commutator-side synchronous rectifier element when the DC-DC converter is in a non-operation state and determining an effective capacity or a characteristic degradation state of the secondary battery on the basis of a decrease in a voltage detected by the output voltage detection circuit at the time of passage of the current through the closed loop or a slope of the decrease in the voltage.