Abstract: A power conversion device according to one embodiment has an inverter that converts direct-current power supplied from a direct-current power source to alternating-current power, a determination unit that determines whether or not a negative-phase sequence voltage on an alternating-current side of the inverter is a predetermined value or greater, and a stop control unit that performs control to stop the inverter in a case where the determination unit determines that the negative-phase sequence voltage is the predetermined value or greater. Further, the stop control unit may perform control to stop the inverter in a case where a positive-phase sequence voltage on the alternating-current side of the inverter is within a predetermined range.

Abstract: A power conversion apparatus includes a power conversion circuit configured to convert DC power into three-phase AC power; and a control device configured to generate a two-phase negative-phase current from a three-phase AC current output from the power conversion circuit, and to detect an open phase on an output side of the power conversion circuit based on a magnitude of an amplitude of the two-phase negative-phase current. The control device may be configured to determine an occurrence of the open phase when the magnitude of the amplitude of the two-phase negative-phase current increases, and an electric current of at least one phase of the three-phase AC current decreases.

Abstract: An elevator monitoring device that can compensate for system voltage when an unbalanced short circuit occurs. A control device for a power conversion device includes: a current command value generator configured to generate a provisional normal phase d-axis current command value, a provisional normal phase q-axis current command value, a provisional reversed phase d-axis current command value, and a provisional reversed phase q-axis current command value to compensate for an alternating current (AC)-side voltage of a power converter; a limiter configured to respectively set limit values of a provisional normal phase d-axis current command value, a provisional normal phase q-axis current command value, a provisional reversed phase d-axis current command value, and a provisional reversed phase q-axis current command value so that the AC-side current value of the power converter does not exceed a preset value; and a controller configured to control the power converter within the limit values.

Abstract: A power conversion device according to one embodiment has an inverter that converts direct-current power supplied from a direct-current power source to alternating-current power, a determination unit that determines whether or not a negative-phase sequence voltage on an alternating-current side of the inverter is a predetermined value or greater, and a stop control unit that performs control to stop the inverter in a case where the determination unit determines that the negative-phase sequence voltage is the predetermined value or greater. Further, the stop control unit may perform control to stop the inverter in a case where a positive-phase sequence voltage on the alternating-current side of the inverter is within a predetermined range.

Abstract: 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.

Abstract: An elevator monitoring device that can compensate for system voltage when an unbalanced short circuit occurs. A control device for a power conversion device includes: a current command value generator configured to generate a provisional normal phase d-axis current command value, a provisional normal phase q-axis current command value, a provisional reversed phase d-axis current command value, and a provisional reversed phase q-axis current command value to compensate for an alternating current (AC)-side voltage of a power converter; a limiter configured to respectively set limit values of a provisional normal phase d-axis current command value, a provisional normal phase q-axis current command value, a provisional reversed phase d-axis current command value, and a provisional reversed phase q-axis current command value so that the AC-side current value of the power converter does not exceed a preset value; and a controller configured to control the power converter within the limit values.

Abstract: A power conversion apparatus includes a power conversion circuit configured to convert DC power into three-phase AC power; and a control device configured to generate a two-phase negative-phase current from a three-phase AC current output from the power conversion circuit, and to detect an open phase on an output side of the power conversion circuit based on a magnitude of an amplitude of the two-phase negative-phase current. The control device may be configured to determine an occurrence of the open phase when the magnitude of the amplitude of the two-phase negative-phase current increases, and an electric current of at least one phase of the three-phase AC current decreases.

Abstract: 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.

Abstract: A power supply system includes a plurality of AC output converters connected in parallel for supplying electric power to an AC load. Each of the plurality of AC output converters includes an output impedance connected to the AC load, a PWM converter configured to convert DC power into AC power, and a controller configured to output a voltage command value to the PWM converter. The controller includes a vector adder configured to perform vector addition of a part of a voltage drop occurring due to a current flowing through the output impedance and a voltage command value of the AC load, and a converter configured to output a voltage command value to the PWM converter based on a vector sum obtained through the vector addition.

Abstract: A power supply system includes a plurality of AC output converters connected in parallel for supplying electric power to an AC load. Each of the plurality of AC output converters includes an output impedance connected to the AC load, a PWM converter configured to convert DC power into AC power, and a controller configured to output a voltage command value to the PWM converter. The controller includes a vector adder configured to perform vector addition of a part of a voltage drop occurring due to a current flowing through the output impedance and a voltage command value of the AC load, and a converter configured to output a voltage command value to the PWM converter based on a vector sum obtained through the vector addition.