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.

A power conversion device includes a power conversion circuit and a power conversion control circuit. The power conversion control circuit is configured to calculate a positive-phase sequence current command signal based on a positive-phase sequence voltage of the three-phase AC output voltage and a positive-phase sequence current of the three-phase AC output current, calculate a negative-phase sequence current command signal based on the first axis negative-phase sequence current command value, the second axis negative-phase sequence current command value, the first axis negative-phase sequence current value, and the second axis negative-phase sequence current value, and generate the switching control signal based on the positive-phase sequence current command signal and the negative-phase sequence current command signal.

A power conversion device includes a power conversion circuit and a power conversion control circuit. The power conversion control circuit is configured to calculate a positive-phase sequence current command signal based on a positive-phase sequence voltage of the three-phase AC output voltage and a positive-phase sequence current of the three-phase AC output current, calculate a negative-phase sequence current command signal based on the first axis negative-phase sequence current command value, the second axis negative-phase sequence current command value, the first axis negative-phase sequence current value, and the second axis negative-phase sequence current value, and generate the switching control signal based on the positive-phase sequence current command signal and the negative-phase sequence current command signal.

A power conversion device includes a power converter including at least a first converter for converting battery power output by a battery into first output power of a first voltage waveform based on an input or set output waveform profile and outputting the first output power from a first terminal pair and a second converter for converting the battery power into second output power of a second voltage waveform of a rectangular shape and outputting the second output power from a second terminal pair and configured to supply a load with third output power of an alternating current (AC) control waveform generated by adding the first output power to the second output power, and a controller configured to output a voltage command value for outputting the first output power as the output waveform profile to the first converter to the power converter on the basis of the input request command value of output power for the load and the voltage value of the third output power output by the power converter.

An integrated circuit for a power supply circuit. The integrated circuit includes an oscillator circuit configured to output an oscillator voltage that rises with a predetermined slope from a first voltage, upon an inductor current of the power supply circuit becoming smaller than a first predetermined value, an error voltage output circuit configured to output an error voltage corresponding to a difference between a reference voltage and a feedback voltage corresponding to the output voltage, a drive circuit configured to turn on and off a transistor of the power supply circuit respectively upon the inductor current becoming smaller than the first predetermined value, and upon the oscillator voltage reaching a second voltage that is based on the error voltage, and an output circuit configured to change the first and/or second voltage based on a rectified voltage obtained by full-wave rectification of the AC voltage, and to output the changed voltage.

An integrated circuit for a power supply circuit. The integrated circuit includes an oscillator circuit configured to output an oscillator voltage that rises with a predetermined slope from a first voltage, upon an inductor current of the power supply circuit becoming smaller than a first predetermined value, an error voltage output circuit configured to output an error voltage corresponding to a difference between a reference voltage and a feedback voltage corresponding to the output voltage, a drive circuit configured to turn on and off a transistor of the power supply circuit respectively upon the inductor current becoming smaller than the first predetermined value, and upon the oscillator voltage reaching a second voltage that is based on the error voltage, and an output circuit configured to change the first and/or second voltage based on a rectified voltage obtained by full-wave rectification of the AC voltage, and to output the changed voltage.

An inverter converts power outputted from a distributed power supply into AC power, and outputs to an AC system. An inverter control circuit generates an AC voltage target value at a time of controlling the inverter, and generates a command value for control of the inverter as a voltage source. When the inverter is introduced into the AC system, the inverter control circuit sets a frequency of the AC voltage target value to a frequency of an AC voltage detected by an AC frequency detection circuit, and controls a phase of the AC voltage target value to be at least a leading phase with respect to the AC voltage of the AC system when a target value of the AC power is in a running direction.

The purpose of the present invention is to provide a power conversion device capable of suppressing an increase in current flowing through a motor even if a voltage command exceeds the amplitude of a carrier wave. To achieve the above purpose, a power conversion device, which controls the drive of a three-phase motor by converting a DC voltage into a voltage command-based voltage through the operation of a switching circuit, comprises: a DC voltage detector which detects a DC voltage; a norm generator which generates a voltage command norm from the voltage command; a modulated wave generator which generates a first modulated wave from the detected DC voltage and the voltage command norm; and a control signal generator which generates a control signal for controlling the operation of the switching circuit from the first modulated wave and the carrier wave, wherein the modulated wave generator generates, for one phase at the timing of the maximum or minimum value of the voltage command, a first modulated wave having a magnitude of 1/2 of the detected DC voltage, and generates, for the remaining two phases, a first modulated wave having a magnitude based on the detected DC voltage and voltage command norm.

A method is provided for operating an inverter of an inverter-based power resource providing electric power to a grid through one or more transformers. The method includes measuring voltages associated with terminals on a selected primary winding and/or measuring voltages associated with terminals on a selected secondary winding; and injecting currents into the primary terminals of the selected primary winding during a fault condition based on the measured voltages being indicative of the type of fault occurring. Preferably the inverter is operated to emulate at least some characteristics of fault currents provided by a generator having rotating magnets or electrical windings. An apparatus is configured to operate in accordance with the method and includes an electrical switching device circuit having input terminals for an inverter-based power resource and output terminals for providing AC electric power to an electric power grid. An inverter controller operates the electrical switching device circuit.

A method is provided for operating an inverter of an inverter-based power resource providing electric power to a grid through one or more transformers. The method includes measuring voltages associated with terminals on a selected primary winding and/or measuring voltages associated with terminals on a selected secondary winding; and injecting currents into the primary terminals of the selected primary winding during a fault condition based on the measured voltages being indicative of the type of fault occurring. Preferably the inverter is operated to emulate at least some characteristics of fault currents provided by a generator having rotating magnets or electrical windings. An apparatus is configured to operate in accordance with the method and includes an electrical switching device circuit having input terminals for an inverter-based power resource and output terminals for providing AC electric power to an electric power grid. An inverter controller operates the electrical switching device circuit.