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: In an electric power conversion device according to an embodiment, a chopper converts electric power from a power supply into direct-current power. An inverter converts the direct-current power into alternating-current power. Pairs of resonant capacitors are connected to a direct-current input section of the inverter. Each of the pairs is in series. Primary windings of high-frequency transformers are connected to the inverter and respective midpoints of the pairs of resonant capacitors. The high-frequency transformers convert the alternating-current power of the inverter. Rectifiers convert alternating-current power supplied from secondary windings of the high-frequency transformers into direct-current power. One or more voltage detectors detect output voltage of one or more of the rectifiers. A control device controls the chopper on the basis of output of the voltage detectors such that an output voltage of the direct-current power comes to a predetermined voltage value.

Abstract: An auxiliary power supply device according to an embodiment includes a high-frequency transformer; a chopper to convert a DC power; an inverter to convert output power of the chopper into AC power and supply the AC power to the high-frequency transformer; a DC capacitor connected to a DC end of the inverter; a resonant capacitor to generate a resonance according to switching of the inverter; a rectifier to convert, into DC power, the AC power supplied from the inverter via the high-frequency transformer; and a controller to calculate a resonant frequency of a resonant circuit including the resonant capacitor based on a value supplied from a detector and detect a decrease in capacity of the resonant capacitor using the resonant frequency and the value of the DC input current.

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: 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: According to an embodiment, a power conversion apparatus includes a transformer, an inverter, a rectifier, a first voltage detector, a second voltage detector, and a control unit. The inverter includes a switch and outputs AC voltage to the primary side of the transformer by an ON/OFF operation of the switch. The rectifier converts the AC voltage from the secondary side of the transformer into DC output voltage. The first voltage detector detects input voltage input to the inverter. The second voltage detector detects the output voltage. The control unit sets, on the basis of the input voltage and the output voltage, permissible ON time for which the switch is set to an ON state such that a value of current output from the inverter does not exceed an upper limit value.

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 vehicle power conversion device includes a two-level converter, a three-level converter and one cooling device. The two-level converter includes a capacitor, first switching devices and second switching devices. The three-level converter includes two capacitors, third switching devices, fourth switching devices and a bidirectional switch. The first and second switching devices are embedded in first power modules, and the third and fourth switching devices are embedded in second power modules. The second power modules have dielectric strength voltages at least equal to a voltage applicable to any one of the two capacitors connected in series included in the three-level converter, and the first power modules have dielectric strength voltages at least equal to a sum of a voltage applicable to any one of the two capacitors connected in series included in the three-level converter and a voltage applicable to the capacitor included in the two-level converter.

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: 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 vehicle power conversion device includes a two-level converter, a three-level converter and one cooling device. The two-level converter includes a capacitor, first switching devices and second switching devices. The three-level converter includes two capacitors, third switching devices, fourth switching devices and a bidirectional switch. The first and second switching devices are embedded in first power modules, and the third and fourth switching devices are embedded in second power modules. The second power modules have dielectric strength voltages at least equal to a voltage applicable to any one of the two capacitors connected in series included in the three-level converter, and the first power modules have dielectric strength voltages at least equal to a sum of a voltage applicable to any one of the two capacitors connected in series included in the three-level converter and a voltage applicable to the capacitor included in the two-level converter.

Abstract: According to an embodiment, a power conversion apparatus for a vehicle is provided with a single-phase two-level converter and a single-phase three-level converter. The single-phase two-level converter is composed of a capacitor, first to fourth controllable switching devices, diodes connected in antiparallel with the controllable switching devices, respectively. The single-phase three-level converter is composed of two series-connected capacitors, fifth to tenth controllable switching devices, diodes connected in antiparallel with the controllable switching devices, respectively. The single-phase two-level converter and the single-phase three-phase converter are connected in series at the AC input/output points. The single-phase two-level converter has smaller switching loss than the single-phase three-level converter, and the single-phase three-level converter has higher withstand voltage property than the single-phase two-level converter.

Abstract: A power conversion apparatus comprises a first converter connected to a second converter. The first converter includes a first capacitor and the second converter includes a second capacitor connected in series to a third capacitor. The capacitors are each connected in parallel with a respective resistor. The power conversion apparatus also includes a bypass switch connected in parallel to the first converter and in series to the second converter. A control module is configured to control a single-phase output voltage by operation of the first converter, the second converter, and the bypass switch.

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 power electronics device has an output connected to an output of a different power electronics device by a power line. The power electronics device includes a detector to detect, from the power line or a space around the power electronics device, an electric power that the different power electronics device superimposes onto an output power, or at least one of an electric power, a sound, and an electromagnetic wave, each having a frequency of a carrier wave that the different power electronics device uses for power conversion. The power electronics device includes a determiner to determine a state of the different power electronics device based on a detection signal obtained through detection performed by the detector.

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: According to one embodiment, a controlling apparatus includes a power phase controlling unit to control the phase of the power to be output to the power line by the power converting apparatus, based on the synchronous signal, and when a disruption of the synchronous signal is detected, control the phase of the power to be output to the power line by the power converting apparatus, based on the synchronous signal received before the disruption. The controlling apparatus includes a communication controlling unit to control the communicating unit such that, for information to determine a master that sends the synchronous signal, the communicating unit performs either one of a receiving from the controlling apparatus for the other power converting apparatus and a sending to the controlling apparatus for the other power converting apparatus, while the power phase controlling unit performs the control based on the synchronous signal received before the disruption.

Abstract: According to an embodiment, a power conversion apparatus for a vehicle is provided with a single-phase two-level converter and a single-phase three-level converter. The single-phase two-level converter is composed of a capacitor, first to fourth controllable switching devices, diodes connected in antiparallel with the controllable switching devices, respectively. The single-phase three-level converter is composed of two series-connected capacitors, fifth to tenth controllable switching devices, diodes connected in antiparallel with the controllable switching devices, respectively. The single-phase two-level converter and the single-phase three-phase converter are connected in series at the AC input/output points. The single-phase two-level converter has smaller switching loss than the single-phase three-level converter, and the single-phase three-level converter has higher withstand voltage property than the single-phase two-level converter.

Abstract: A power conversion apparatus comprises a first converter connected to a second converter. The first converter includes a first capacitor and the second converter includes a second capacitor connected in series to a third capacitor. The capacitors are each connected in parallel with a respective resistor. The power conversion apparatus also includes a bypass switch connected in parallel to the first converter and in series to the second converter. A control module is configured to control a single-phase output voltage by operation of the first converter, the second converter, and the bypass switch.