Patent ID: 8581553

Claim:
A system power leveling device comprising: a bidirectional converter connected to a system bus line providing electric power to a load from a power source, the bidirectional converter comprising a first switching element and a second switching element; a power storage device connected to the bidirectional converter; a first specifying section configured to specify a power consumption of the load; a charge-discharge control section configured to control charging and discharging of the power storage device by controlling the bidirectional converter based on the specified power consumption; and a second specifying section configured to specify one of a current and an electric power of the charge or the discharge, wherein the charge-discharge control section comprises: a first on/off control section configured to: deactivate a first of the first switching element and the second switching element when the power storage device is charging or discharging; one of activate and deactivate a second of the first switching element and the second switching element until a difference between a target value of the current or the electric power of the charge or the discharge and the specified value specified by the second specifying section becomes smaller than a first threshold; and perform a first feed-back control such that the specified value approaches the target value, by using a pulse width modulation for a on/off operation of the second of the first switching element and the second switching element; a determining section configured to determine whether the difference is larger than a second threshold which is larger than the first threshold, when starting the charge or the discharge; and a second on/off control section configured to: when the charge or the discharge is performed, while one of the first and the second switching elements is kept off, deactivate the first of the first switching element and the second switching element when the power storage device is charging or discharging; and perform a second feed-back control such that the specified value approaches target value, by using a pulse width modulation for an on/off operation of the second of the first switching element and the second switching element, wherein when the difference is determined to be larger than the second threshold by the determining section, the first feed-back control by the first on/off control section is performed, and when the difference is determined equal to or less than the second threshold by the determining section, the second feed-back control by the second on/off control section is performed.