Abstract: A power conversion device includes a first relay unit, one or more second relay units, and a safety control unit. The first relay unit includes a first logic processing unit that transmits a response signal supplied from a first power conversion unit and a response signal of a downstream side of its first relay unit to an upstream side. Each of the one or more second relay units includes a second logic processing unit that transmits a response signal transmitted from one second power conversion unit among the one or more second power conversion units and a response signal transmitted from a downstream side of the one second relay unit to an upstream side of the one second relay unit.

Abstract: A power converter including a diode converter, an inverter, a smoothing capacitor, a resistor; a current sensor; an estimation unit; and a control unit. The diode converter rectifies an alternating current from a power supply. The inverter is formed such that a DC side is connected to a DC output of the diode converter and an AC side is connected to an electric motor and includes a semiconductor switching element which converts DC power on the DC side into AC power and a reverse connection diode which is connected in antiparallel with the semiconductor switching element. The smoothing capacitor is provided in the DC output of the diode converter. The resistor is connected in parallel with the smoothing capacitor. The current sensor detects a load current flowing between the inverter and the electric motor.

Abstract: A motor drive system of the embodiment includes a power converter, a state detector, a frequency calculator, a frequency correction command generator, a drive amount limiter, and a speed controller. The power converter drives a motor by PWM control. The state detector detects a drive state of the motor. The frequency calculator detects a size of a specific frequency component which fluctuates according to the drive state by using an index value indicating the drive state. The frequency correction command generator generates a correction command of a carrier frequency used for the PWM control on the basis of a detected result of periodic fluctuation of the drive state. The drive amount limiter limits a drive amount of the motor.

Abstract: A power conversion apparatus capable of supplying a required reactive power while dynamically changing a dead band near 0 reactive current and maintaining a balance of DC voltage is provided. The power conversion apparatus including a three-level converter, a PWM controller for the three-level converter, an input current detector of the three-level converter, a coordinate converter that converts the current into a d-axis and q-axis current feedback, the reactive power control unit that controls a reactive power and outputs an reactive current reference, a d-axis current control unit having a dead band part for setting the d-axis current reference with hysteresis characteristics in the q-axis current feedback, and outputs the d-axis voltage reference, a q-axis current control unit that outputs a q-axis voltage reference based on the q-axis current reference, an inverse coordinate converter that outputs a three-phase AC voltage command based on the d-axis and q-axis voltage reference.

Abstract: A power conversion device according to an embodiment includes a cell, a first sensor, a second sensor, a storage, a first controller, and a second controller. The first controller is configured to control or protect the cell on the basis of at least one of an output result of the first sensor and an output result of the second sensor. The second controller, in a case in which a change in at least one of the output result of the first sensor and the output result of the second sensor satisfies a first condition, is configured to execute at least one of a first operation of storing the output result of the first sensor in the storage, a second operation of storing the output result of the first sensor in the storage over a second period longer than a first period, and a third operation of storing the output result of the second sensor instead of the output result of the first sensor.

Abstract: A power converter according to an aspect of an embodiment includes: a diode converter; an inverter; a smoothing capacitor; a resistor; a current sensor; an estimation unit; and a control unit. The diode converter rectifies an alternating current from a power supply. The inverter is formed such that a DC side is connected to a DC output of the diode converter and an AC side is connected to an electric motor and includes a semiconductor switching element which converts DC power on the DC side into AC power and a reverse connection diode which is connected in antiparallel with the semiconductor switching element. The smoothing capacitor is provided in the DC output of the diode converter. The resistor is connected in parallel with the smoothing capacitor. The current sensor detects a load current flowing between the inverter and the electric motor. The estimation unit calculates an estimation value of the DC voltage Vdc on the DC side on the basis of a current value I detected by the current sensor.

Abstract: A power conversion apparatus capable of supplying a required reactive power while dynamically changing a dead band near 0 reactive current and maintaining a balance of DC voltage is provided. The power conversion apparatus comprises a three-level converter, a PWM controller for the three-level converter, an input current detector of the three-level converter, a coordinate converter that converts the current into a d-axis and q-axis current feedback, the reactive power control unit that controls a reactive power and outputs an reactive current reference, a d-axis current control unit having a dead band part for setting the d-axis current reference with hysteresis characteristics in the q-axis current feedback, and outputs the d-axis voltage reference, a q-axis current control unit that outputs a q-axis voltage reference based on the q-axis current reference, an inverse coordinate converter that outputs a three-phase AC voltage command based on the d-axis and q-axis voltage reference.

Abstract: A power conversion apparatus comprises, a converter that receives a three-phase AC power supply 1 and outputs a DC voltage, an inverter that is connected to the output of the converter and drives the AC motor via the output switch, a power switch for directly driving an AC motor from the AC power supply, a current detector for detecting the output current of the inverter, a voltage detector and a current detector for detecting the voltage and current of the power supply system on the input side of the converter, respectively, and a control unit for controlling the three-phase output voltage of the inverter based on the voltage command of three phases. The control unit includes a vector control unit that performs vector control of the AC motor and a synchronous incorporation controller. The synchronous incorporation controller switches to operate the inverter as a reactive power controller for the power supply system after closing the power switch to synchronize the AC motor with the AC power supply.

Abstract: A power conversion system that has two power conversion apparatuses each including a converter that can control a DC voltage and an inverter and that drives the AC motor by connecting the outputs of the two inverters in parallel is provided. The output voltage of one of the converters is controlled according to the difference between the detection currents detected by the two current detectors for detecting the output currents of the two inverters so that a cross current flowing through the two inverters is suppressed.

Abstract: A power conversion device according to an embodiment includes a cell, a first sensor, a second sensor, a storage, a first controller, and a second controller. The first controller is configured to control or protect the cell on the basis of at least one of an output result of the first sensor and an output result of the second sensor. The second controller, in a case in which a change in at least one of the output result of the first sensor and the output result of the second sensor satisfies a first condition, is configured to execute at least one of a first operation of storing the output result of the first sensor in the storage, a second operation of storing the output result of the first sensor in the storage over a second period longer than a first period, and a third operation of storing the output result of the second sensor instead of the output result of the first sensor.

Abstract: A power conversion system that has two power conversion apparatuses 2 each including a converter 21 that can control a DC voltage and an inverter 22 and that drives the AC motor 4 by connecting the outputs of the two inverters 22A and 22B in parallel is provided. The output voltage of one of the converters is controlled according to the difference between the detection currents detected by the two current detectors 6A and 6B for detecting the output currents of the two inverters 22A and 22B, respectively, so that a cross current flowing through the two inverters 22A and 22B is suppressed.

Abstract: A power conversion apparatus comprises, a converter that receives a three-phase AC power supply 1 and outputs a DC voltage, an inverter that is connected to the output of the converter and drives the AC motor via the output switch, a power switch for directly driving an AC motor from the AC power supply, a current detector for detecting the output current of the inverter, a voltage detector and a current detector for detecting the voltage and current of the power supply system on the input side of the converter, respectively, and a control unit for controlling the three-phase output voltage of the inverter based on the voltage command of three phases. The control unit includes a vector control unit that performs vector control of the AC motor and a synchronous incorporation controller. The synchronous incorporation controller switches to operate the inverter as a reactive power controller for the power supply system after closing the power switch to synchronize the AC motor with the AC power supply.

Abstract: A power conversion apparatus having a converter, an inverter controlled by inverter controller, and an input power source fluctuation detecting and controlling circuit is proposed. The input power source fluctuation detecting and controlling circuit includes an input power source fluctuation detector and a converter failure detector to detect overcurrent and/or overvoltage of the converter. When both of the input power source fluctuation and the converter failure are detected, the converter is gate blocked, and the inverter continues its operation, and when the DC voltage become lower than a threshold voltage during the converter is gate blocking, the input power source fluctuation detecting and controlling circuit outputs an inverter control changeover flag to the inverter controller for switching a contents of inverter control.

Abstract: A power conversion apparatus having a converter, an inverter controlled by inverter controller, and an input power source fluctuation detecting and controlling circuit is proposed. The input power source fluctuation detecting and controlling circuit includes an input power source fluctuation detector and a converter failure detector to detect overcurrent and/or overvoltage of the converter. When both of the input power source fluctuation and the converter failure are detected, the converter is gate blocked, and the inverter continues its operation, and when the DC voltage become lower than a threshold voltage during the converter is gate blocking, the input power source fluctuation detecting and controlling circuit outputs an inverter control changeover flag to the inverter controller for switching a contents of inverter control.