Patent ID: 8183833
Filing Date: 2012-05-22
Classification: H02J,Y02T

Abstract:
1. A voltage balancer device, for a battery pack composed of a plurality of secondary battery units connected in series, configured to discharge a voltage of the secondary battery unit to a desired voltage for voltage adjustment between the secondary battery units, comprising: a first discharge path connected in parallel to and placed per secondary battery unit, the first discharge path having a first discharging device and a first switching element; a second discharge path connected in parallel to and placed per secondary battery unit, the second discharge path having a second discharging device and a second switching element, the second discharging device being different than the first discharging device, a set of the first discharging device and the first switching element in the first discharge path and a set of the second discharging device and the second switching element in the second discharge path are connected in parallel with each other and further in parallel to the corresponding secondary battery unit; and a controller configured to limit a current flowing through the first or second discharge path so that an actual current flowing through the first or second discharge path at the desired voltage becomes lower than a theoretical current at the desired voltage of the first or second discharge path; wherein the first discharge path and the second discharge path are connected in parallel with each other, and the first and second switching elements are operated by the controller so that discharge through the first discharge path is changed to discharge through the second discharge path and a current flowing through the second discharge path is smaller than a current flowing through the first discharge path during discharge to the desired voltage.