Abstract: Control is performed such that, for generating an AC voltage from a DC voltage, a period during which a DC/DC converter boosts the DC voltage and an inverter performs one of polarity non-inversion passing and polarity inversion passing, and a period during which the DC/DC converter is stopped and the inverter performs step-down operation and one of polarity non-inversion passing and polarity inversion passing, arise alternately in one AC cycle. Gate blocking is temporarily performed for only the DC/DC converter, upon occurrence of a phenomenon in which, by start of power feeding to a load connected to an AC electric path, an absolute value of a current flowing through an AC reactor reaches a predetermined converter gate block threshold value lower than an instantaneous overcurrent protection threshold value.

Abstract: A power conversion device provided between a DC power supply and an AC electric path, including: a breaking device provided to at least one line of an output electric path in the power conversion device; a first voltage sensor provided on a primary side of the breaking device; a second voltage sensor provided on a secondary side of the breaking device; and a determination unit which calculates a primary-side voltage and a secondary-side voltage, and a primary-side phase and a secondary-side phase and determines that the breaking device is opened, by occurrence of an event in which an absolute value of a voltage difference between the primary-side voltage and the secondary-side voltage is greater than a voltage difference threshold value and an absolute value of a phase difference between the primary-side phase and the secondary-side phase is greater than a phase difference threshold value

Abstract: This power conversion device performs DC/AC power conversion via an intermediate bus, and includes: a first DC/DC converter provided between a DC power supply and the intermediate bus; a second DC/DC converter provided between a DC-side capacitor and the intermediate bus; an intermediate capacitor connected to the intermediate bus; a DC/AC converter provided between the intermediate bus and an AC grid; and a control unit configured to control the first DC/DC converter, the second DC/DC converter, and the DC/AC converter, the control unit making such current command value setting that mainly the second DC/DC converter supplies a reactive current flowing through the intermediate bus.

Abstract: An inverter device includes a circuit configuration for converting, to AC power, DC powers respectively given from a first power supply and a second power supply which outputs power with voltage lower than that of the first power supply. The inverter device includes: a first step-up circuit; a second step-up circuit; an inverter circuit connected to both step-up circuits connected in parallel to each other, the inverter circuit configured to convert powers given from both step-up circuits to AC power; and a control unit configured to multiply a power value including the AC power outputted from the inverter circuit, by a ratio of a power value of the DC power of each step-up circuit to a total power value obtained by summing the DC powers of both step-up circuits, and set a current target value for each step-up circuit based on a value obtained by the multiplication.

Abstract: Control is performed such that, for generating an AC voltage from a DC voltage, a period during which a DC/DC converter boosts the DC voltage and an inverter performs one of polarity non-inversion passing and polarity inversion passing, and a period during which the DC/DC converter is stopped and the inverter performs step-down operation and one of polarity non-inversion passing and polarity inversion passing, arise alternately in one AC cycle. Gate blocking is temporarily performed for only the DC/DC converter, upon occurrence of a phenomenon in which, by start of power feeding to a load connected to an AC electric path, an absolute value of a current flowing through an AC reactor reaches a predetermined converter gate block threshold value lower than an instantaneous overcurrent protection threshold value.

Abstract: This power supply unit includes: an AC path from an input end to an output end; a first voltage sensor configured to detect an input voltage at the input end; a second voltage sensor configured to detect an output voltage at the output end; a bidirectional inverter connected to the AC path; a storage battery connected to the AC path via the bidirectional inverter; an AC switch provided between the input end and a point at which the bidirectional inverter is connected to the AC path; and a control unit configured such that, in a state in which the AC switch is controlled to be opened, if current conduction via the AC switch is detected on the basis of an operation state of the bidirectional inverter, the input voltage, and the output voltage, the control unit determines that the AC switch has failed, and stops the bidirectional inverter.

Abstract: A control unit of a power conversion device calculates a current target value and a voltage target value for a DC/AC converter on the basis of an output current target value, to control the DC/AC converter, and calculates a current target value for the DC/DC converter on the basis of the current target value and the voltage target value, and a voltage target value for the DC/DC converter, to control the DC/DC converter, thereby controlling output of an AC power. The control unit selects, as the voltage target value for the DC/DC converter, a greatest value at a present time, from among a DC voltage value of the DC power supply, an absolute value of a voltage target value for an AC side of the DC/AC converter, and a DC voltage lower limit value which is a predetermined value smaller than a peak value of the absolute value.

Abstract: This power conversion device includes: conversion devices for supplying AC powers to respective phases with respect to the neutral point of a three-phase AC system via reactors; and a control unit for controlling the conversion devices. Each conversion device includes: a step-up circuit for stepping up the DC input voltage value of DC power; and a single-phase inverter circuit.

Abstract: This power conversion system is composed of a DC power supply circuit and a power conditioner which are connected to each other. The power conditioner includes: a first DC/DC converter provided between the DC power supply circuit and a DC bus; and an inverter provided between the DC bus and an AC electric path and configured to perform switching operation in such a manner that the inverter and the first DC/DC converter alternately have stop periods in an AC half cycle. The DC power supply circuit includes: a storage battery; and a second DC/DC converter of a bidirectional type, provided between the storage battery and the first DC/DC converter and including a DC reactor. The power conversion system includes a control unit configured to control current flowing through the DC reactor of the second DC/DC converter to have a constant value.

Abstract: This power conversion device performs DC/AC power conversion via an intermediate bus, and includes: a first DC/DC converter provided between a DC power supply and the intermediate bus; a second DC/DC converter provided between a DC-side capacitor and the intermediate bus; an intermediate capacitor connected to the intermediate bus; a DC/AC converter provided between the intermediate bus and an AC grid; and a control unit configured to control the first DC/DC converter, the second DC/DC converter, and the DC/AC converter, the control unit making such current command value setting that mainly the second DC/DC converter supplies a reactive current flowing through the intermediate bus.

Abstract: This power conversion device performs power conversion via an intermediate bus between a plurality of DC power supplies and an AC grid, and includes: a plurality of DC/DC converters respectively provided between the intermediate bus and the plurality of DC power supplies; an intermediate capacitor connected to the intermediate bus; a DC/AC converter provided between the intermediate bus and the AC grid; and a control unit configured to control the plurality of DC/DC converters and the DC/AC converter, the control unit performing control of allocating, to the plurality of DC/DC converters, an active power to be outputted from the DC/AC converter, and allocating, to the plurality of DC/DC converters, a sum of reactive powers to be outputted from the DC/AC converter and the intermediate capacitor, using an allocation coefficient different from an allocation coefficient for the active power.

Abstract: This power supply device includes: an AC path from an input end to an output end; a current sensor configured to detect a current flowing through the AC path; a conversion unit connected to the AC path and being capable of bidirectional power conversion; a storage battery connected to the AC path via the conversion unit; an AC switch provided between the input end and a point at which the conversion unit is connected to the AC path, the AC switch including parallel body of a relay contact and a semiconductor switch; and a control unit configured to control the conversion unit and the AC switch. When the control unit executes a current conduction mode for the first time, and when the current sensor detects an excessive current during the current conduction mode, the control unit closes only the relay contact while keeping the semiconductor switch opened.

Abstract: A power conversion device includes a switch connected to an AC system; an AC/DC converter; and a DC/DC converter. A control unit compares an absolute value of an AC voltage target value based on the AC voltage with a DC voltage target value based on the storage battery voltage, and executes, on the basis of a magnitude relation of the values, a control method such that a period during which step-up operation is performed through switching operation mainly using one of the AC/DC converter and the DC/DC converter, and a period during which step-down operation is performed through switching operation mainly using the other one of the converters, alternately arise. When starting charging/discharging of the storage battery, the control unit causes the switch to close at zero cross timing of the AC voltage, and thereafter, causes charging/discharging to start from the switching operation through which the step-down operation is performed.

Abstract: Duties of control for DC/AC and DC/DC conversion units are determined by considering electric influences of a filter circuit, a capacitor connected to a DC bus, and a DC reactor for an output voltage command value for supplying an AC voltage to a load. The DC/DC conversion unit is controlled to convert a DC voltage into a DC bus voltage waveform alternately having a period of a pulsating current waveform corresponding to the absolute value of the AC voltage and a period of the DC voltage as a pulsating current minimum value. The DC/AC conversion unit is controlled to perform step-down operation during the period of the DC voltage and thus perform conversion into a waveform of the absolute value of the AC voltage corresponding to the period of the DC voltage, and also to perform polarity inversion per one pulsating current cycle.

Abstract: This conversion device includes: a DC bus with a smoothing capacitor; a first converter provided between a DC power supply and the DC bus to perform DC/DC conversion; a second converter provided between the DC bus and an AC electric path to perform DC/AC or AC/DC conversion by a full-bridge of switching elements; a voltage sensor for detecting voltage between both ends of the capacitor as DC bus voltage; and a control unit which causes a part of an absolute value of an AC waveform, and a DC waveform, to alternately arise as the DC bus voltage by selectively causing the first converter and the second converter to operate in one AC cycle of the AC electric path, the control unit detecting arm short-circuit in the second converter on the basis of a degree of reduction, in the DC bus voltage, that occurs during operation of the second converter.

Abstract: Provided is a conversion device that converts DC power provided from a DC power supply, to AC power and supplies the AC power to a load, the conversion device including: a filter circuit connected to the load and including an AC reactor and a first capacitor; a DC/AC inverter connected to the load via the filter circuit; a DC/DC converter provided between the DC power supply and the DC/AC inverter; a second capacitor provided between the DC/AC inverter and the DC/DC converter; and a control unit configured to set a current target value for the DC/DC converter to thereby be synchronized with current of the AC power, based on voltage of the AC power, voltage variation due to current flowing through the AC reactor and an impedance thereof, reactive currents respectively flowing through the first capacitor and the second capacitor, and voltage of the DC power.

Abstract: A power conversion device includes: a conversion device for each phase which converts DC voltage inputted from a DC power supply, to voltage having an AC waveform to be outputted to each phase with respect to a neutral point of three-phase AC; and a control unit which controls these conversion devices. Each conversion device includes: a first conversion unit which has a DC/DC converter including an isolation transformer, and a capacitor, and which converts the inputted DC voltage to voltage containing a pulsating-current waveform corresponding to the absolute value of voltage obtained by superimposing a third-order harmonic on a fundamental wave as the AC waveform to be outputted; and a second conversion unit which has a full-bridge inverter for inverting the polarity of the voltage containing the pulsating-current waveform, per one cycle, thereby converting the voltage to voltage having the AC waveform.

Abstract: A conversion device includes: a DC bus provided between a DC power supply and an AC power supply; a first converter provided between the DC power supply and the DC bus to perform DC/DC conversion; a second converter provided between the DC bus and the AC power supply to perform DC/AC or AC/DC conversion; and a control unit configured to selectively cause the first converter and the second converter to operate within one cycle of the AC power supply, to alternately generate a part of an absolute value of an AC waveform, and a DC waveform, as voltage of the DC bus, wherein the control unit adds a compensation value in a positive direction, to a voltage target value for the DC bus, at a timing that should have corresponded to a discontinuity point where the AC waveform and the DC waveform are connected to each other.

Abstract: Provided is a power conversion device including: a conversion device for each phase which converts DC voltage inputted from a DC power supply, to voltage having an AC waveform to be outputted to each phase with respect to a neutral point of three-phase AC; and a control unit which controls these conversion devices. Each conversion device includes: a first converter which has a DC/DC converter including an isolation transformer, and a capacitor, and which converts the inputted DC voltage to voltage containing a pulsating DC voltage waveform corresponding to the absolute value of the AC waveform to be outputted; and a second converter which is provided at a stage subsequent to the first converter and has a full-bridge inverter, and which inverts the polarity of the voltage containing the pulsating DC voltage waveform, per one cycle, thereby converting the voltage to voltage having the AC waveform.

Abstract: This conversion device converts DC powers from a plurality of DC power supplies, to AC power and supplies the AC power to a load. The conversion device includes: a filter circuit including an AC reactor and a first capacitor; a DC/AC inverter connected to the load via the filter circuit; DC/DC converters provided between the respective plurality of DC power supplies and the DC/AC inverter; a second capacitor provided between the DC/AC inverter and the DC/DC converters; and a control unit configured to set a current target value for each of the DC/DC converters to thereby be synchronized with current of the AC power, based on voltage of the AC power, voltage variation due to current flowing through the AC reactor and an impedance thereof, reactive currents respectively flowing through the first capacitor and the second capacitor, and voltage of each DC power.