Abstract: According to one embodiment, a power converter includes an inverter and a controller. The inverter operates in an interconnected operation mode in which a grid is connected to an electric load and an isolated operation mode in which the inverter is connected to the electric load, for generating power from a local power supply. The controller detects a frequency difference and a phase difference between an inverter output from the inverter and grid power. The controller calculates, based on the frequency difference and the phase difference, an output frequency pattern to be used for synchronizing the inverter output with the grid power. The controller controls, when switching from the isolated operation mode to the interconnected operation mode, a frequency of the inverter output based on the output frequency pattern.

Abstract: According to one embodiment, a power converter includes an inverter and a controller. The inverter operates in an interconnected operation mode in which a grid is connected to an electric load and an isolated operation mode in which the inverter is connected to the electric load, for generating power from a local power supply. The controller detects a frequency difference and a phase difference between an inverter output from the inverter and grid power. The controller calculates, based on the frequency difference and the phase difference, an output frequency pattern to be used for synchronizing the inverter output with the grid power. The controller controls, when switching from the isolated operation mode to the interconnected operation mode, a frequency of the inverter output based on the output frequency pattern.

Abstract: A charging/discharging apparatus according to the present embodiment comprises first and second electrode terminals inputting or outputting direct-current power. First to third switching elements are connected in series between the first electrode and the second electrode. A first electric storage is connected in parallel to the second switching element located between the first switching element and the third switching element. A second electric storage is connected in parallel to the third switching element. First to third diodes are respectively connected in antiparallel to the first to third switching elements.

Abstract: An apparatus according to an embodiment includes a control circuit to control operations of an inverter and a switch. The control circuit judges whether or not a power system has a power failure, based on values of the system voltage and a frequency of the power system; and calculates a phase difference between a phase of the output voltage of the inverter and a phase of the system voltage and generate, by means of the phase difference, an output frequency pattern for changing a frequency of the output voltage of the inverter. The control circuit, when it is judged that the power system has recovered from the power failure, controls the inverter to change the frequency of the output voltage of the inverter in line with the output frequency pattern, and closes the switch after the phase difference becomes smaller than or equal to a threshold.

Abstract: A power supply apparatus includes a control circuit, and first and second power storage connected to a DC link circuit between an inverter and a converter. The control circuit, while the AC power supply is in a normal condition, controls the first power storage to discharge when the control circuit detects that electric power consumption exceeds a threshold, and controls at least one of the first and second power storage to charge when the control circuit detects that the electric power consumption does not exceed the threshold, and while the AC power supply is in an abnormal condition, controls the second power storage to discharge, and controls the first power to discharge when it is detected that the electric power consumption exceeds the threshold.

Abstract: An apparatus according to an embodiment includes a control circuit to control operations of an inverter and a switch. The control circuit judges whether or not a power system has a power failure, based on values of the system voltage and a frequency of the power system; and calculates a phase difference between a phase of the output voltage of the inverter and a phase of the system voltage and generate, by means of the phase difference, an output frequency pattern for changing a frequency of the output voltage of the inverter. The control circuit, when it is judged that the power system has recovered from the power failure, controls the inverter to change the frequency of the output voltage of the inverter in line with the output frequency pattern, and closes the switch after the phase difference becomes smaller than or equal to a threshold.

Abstract: A charging/discharging apparatus according to the present embodiment comprises first and second electrode terminals inputting or outputting direct-current power. First to third switching elements are connected in series between the first electrode and the second electrode. A first electric storage is connected in parallel to the second switching element located between the first switching element and the third switching element. A second electric storage is connected in parallel to the third switching element. First to third diodes are respectively connected in antiparallel to the first to third switching elements.

Abstract: A power supply apparatus includes a control circuit, and first and second power storage connected to a DC link circuit between an inverter and a converter. The control circuit, while the AC power supply is in a normal condition, controls the first power storage to discharge when the control circuit detects that electric power consumption exceeds a threshold, and controls at least one of the first and second power storage to charge when the control circuit detects that the electric power consumption does not exceed the threshold, and while the AC power supply is in an abnormal condition, controls the second power storage to discharge, and controls the first power to discharge when it is detected that the electric power consumption exceeds the threshold.

Abstract: A circuit configured to, for each of values of output currents output from power conversion devices connected in parallel to one another and driven based on common ON signals applied to the power conversion devices, output a difference between the output current value and a reference value when a polarity of the output current value is positive, and output a difference between an absolute value of the output current value and an absolute value of the reference value when the polarity of the output current value is negative; and a circuit configured to output adjustment time signals each of which indicates an amount of a delay time of a rising timing or a falling timing of the ON signal, according to an output value of the output current difference calculation circuit.

Abstract: A circuit according to an embodiment includes a circuit configured to, for each of values of output currents output from power conversion devices connected in parallel to one another and driven based on common ON signals applied to the power conversion devices, output a difference between the output current value and a reference value when a polarity of the output current value is positive, and output a difference between an absolute value of the output current value and an absolute value of the reference value when the polarity of the output current value is negative; and a circuit configured to output adjustment time signals each of which indicates an amount of a delay time of a rising timing or a falling timing of the ON signal, according to an output value of the output current difference calculation circuit.

Abstract: According to one embodiment, an inverter including a detector which detects a value of an output voltage and a value of an output current; a command value input unit which is capable of receiving a current command value; a current command value compensating unit which, when the value of the output voltage detected by the detector is equal to or lower than a predetermined value, computes a compensation current value for compensating the current command value; an adder which adds the compensation current value to the current command value and outputs the compensated current command value; and a current controller which computes a voltage command value so that a difference between the compensated current command value and the output current detected by the detector becomes zero.

Abstract: An energy management device includes a measurement manager and a communicator. The measurement manager manages energy information based on a physical quantity measured from at least one measurement object belonging to each of a plurality of energy types in a customer. The communicator communicates the energy information of each of the energy types to another device over a network.

Abstract: According to one embodiment, an inverter including a detector which detects a value of an output voltage and a value of an output current; a command value input unit which is capable of receiving a current command value; a current command value compensating unit which, when the value of the output voltage detected by the detector is equal to or lower than a predetermined value, computes a compensation current value for compensating the current command value; an adder which adds the compensation current value to the current command value and outputs the compensated current command value; and a current controller which computes a voltage command value so that a difference between the compensated current command value and the output current detected by the detector becomes zero.

Abstract: A power conversion device includes a main circuit unit, a first current detector, a second current detector, a voltage detector, and a controller. The main circuit unit is connected to a DC voltage source and an AC power system. The main circuit unit includes an inverter including a plurality of switching elements. The main circuit unit converts a DC power to an AC power. The controller decides that whether the output current of the inverter falls within a range between an upper limit value and a lower limit value, stop an operation of the switching elements when the output current of the inverter falls beyond the range, and resume the operation of the switching elements when the output current of the inverter returns into the range.

Abstract: A power conversion device includes a main circuit unit, a first current detector, a second current detector, a voltage detector, and a controller. The main circuit unit is connected to a DC voltage source and an AC power system. The main circuit unit includes an inverter including a plurality of switching elements. The main circuit unit converts a DC power to an AC power. The controller decides that whether the output current of the inverter falls within a range between an upper limit value and a lower limit value, stop an operation of the switching elements when the output current of the inverter falls beyond the range, and resume the operation of the switching elements when the output current of the inverter returns into the range.

Abstract: According to one embodiment, a controlling apparatus comprises an acquiring unit that acquires a power value of a power line, the power line transmitting power between a first grid and a second grid, the first grid including a first power generating apparatus and a power converting apparatus that outputs an alternating-current power based on a power generated by the first power generating apparatus, the second grid including a second power generating apparatus. The controlling apparatus comprises a controlling unit that controls the alternating-current power to be output by the power converting apparatus such that the power value does not fall within a dead band.

Abstract: An energy management device includes a measurement manager and a communicator. The measurement manager manages energy information based on a physical quantity measured from at least one measurement object belonging to each of a plurality of energy types in a customer. The communicator communicates the energy information of each of the energy types to another device over a network.

Abstract: An uninterruptable power supply (UPS) designed to switch power inputs between an alternating current mode and a battery mode by adjusting the amplitude and/or frequency windows of the input voltage so that the uninterruptible power supply accepts the unstable voltage and/or frequency. This prevents the uninterruptible power supply to switch back to the battery mode during a transfer time between the battery mode and the AC mode. The uninterruptable power supply includes a control circuit. The control circuit modifies the monitored value and/or actual amplitude and/or the frequency window when unstable amplitude and/or an unstable frequency are detected at the input terminal of the input voltage.

Abstract: An uninterruptable power supply (UPS) designed to switch power inputs between an alternating current mode and a battery mode having a sensor to monitor a load current, and a central processing unit (CPU) to boost a bus voltage of the uninterruptable power supply by increasing a calculated reference voltage to a target reference voltage by a slope. The calculated reference voltage is calculated by the CPU based on a voltage drop value in main capacitors that occurs during a transfer time between the battery mode and the AC mode. The target reference voltage is the voltage across an equivalent circuit of the main capacitors before the voltage drop. The slope is based on a ratio of a voltage drop value across an equivalent circuit of main capacitors and a charging up time to reach the target reference voltage.

Abstract: An uninterruptible power supply with an input terminal and an output terminal, a main switch connected to the input terminal, an input filter circuit connected to the main switch, a rectifier circuit connected to the input filter circuit, a main capacitor connected to the rectifier circuit, a switching device connected to the capacitor and the output terminal, a voltage boost circuit connected to the capacitor and a battery input terminal, a slope control circuit connected to the voltage boost circuit, a slope selection circuit connected to the slope control circuit, and a control board connected to the slope selection circuit, where the control board has a central processing unit and memory.