Abstract: A control system of a power converter includes a plurality of carrier wave generating units which are respectively provided for a plurality of power converters connected between a plurality of DC power supplies and a common AC power supply and which are configured to respectively generate carrier waves on the basis of an AC voltage of the AC power supply. The control system of the power converter can thereby synchronize carrier phases of a plurality of power converters.

Abstract: A distributed-power-supply power conversion system includes a plurality of power inverters configured to invert DC power to AC power; and a control device configured to select at least one power inverter from the plurality of power inverters as a power inverter used for testing, and configured to perform an energization test of the power inverter used for testing in a state where an AC side of the power inverter used for testing is disconnected from a system, and is connected to an AC power supply device and to a load bank, and a voltage on the AC side of the power inverter used for testing is established. The distributed-power-supply power conversion system can perform an energization test of a power inverter before a system receives power.

Abstract: A power conversion system includes: a power converter connected to an alternate-current power supply; a direct-current capacitor connected to a direct-current side of the power converter; a first alternate-current switch connected between the power converter and the alternate-current power supply; an inrush current suppressor connected in parallel to the first alternate-current switch, between the power converter and the alternate-current power supply, and including a charging resistance or a charging reactor; a second alternate-current switch connected in parallel to the first alternate-current switch and in series to the inrush current suppressor, between the power converter and the alternate-current power supply; and a control device configured to control the power converter so that the first alternate-current switch is open, the second alternate-current switch is closed, and a voltage applied to the direct-current capacitor reaches a voltage that is equal to or exceeds a preset voltage.

Abstract: A control apparatus is a control apparatus for a power conversion apparatus including at least one AC capacitor disposed on the output side of an inverter and disconnected from a circuit when the AC capacitor malfunctions and including a current component extractor that acquires current values of the current flowing through the AC capacitor during synchronization control that synchronizes the output voltage from the inverter with a system voltage of a system, the synchronization control performed during activation of the power conversion apparatus with an AC switch on the side facing the system open, and extracts the value of a current component having a frequency synchronized with the frequency of the output voltage from the inverter out of the current values.

Abstract: A control device for a power converter that can suppress oscillation of an output voltage of the power converter. The control device for the power converter includes an overvoltage detector configured to detect an overvoltage on an output side of the power converter and a controller configured to, when the overvoltage on the output side of the power converter is detected by the overvoltage detector, perform gate block after reducing a current command value given to the power converter. With the configuration, when the overvoltage on the output side of the power converter is detected, the control device performs the gate block after reducing the current command value given to the power converter. Accordingly, it is possible to suppress oscillation of an output voltage of the power converter.

Abstract: An electric-power converter includes a plurality of direct-current power supplies, a plurality of power conversion circuits provided corresponding to the respective direct-current power supplies, an alternating-current power system configured to cause a plurality of alternating-current ends provided in the respective power conversion circuits to be directly connected in parallel through a parallel connection point, and to supply the alternating-current power output from the plurality of alternating-current ends to an alternating-current side through the parallel connection point, a plurality of grounding wires each configured to connect at least two of a plurality of direct-current negative buses between the plurality of direct-current power supplies and the plurality of power conversion circuits, to earth, and a plurality of diodes inserted in series into the respective grounding wires, and each including a cathode side connected to the corresponding direct-current negative bus and an anode side grounded.

Abstract: A control system of a power converter includes a plurality of carrier wave generating units which are respectively provided for a plurality of power converters connected between a plurality of DC power supplies and a common AC power supply and which are configured to respectively generate carrier waves on the basis of an AC voltage of the AC power supply. The control system of the power converter can thereby synchronize carrier phases of a plurality of power converters.

Abstract: A control device is a control device of a power conversion device, and includes a conversion value calculation unit that acquires a current value of a current flowing in an alternating-current capacitor connected to a capacitor circuit in an output circuit on an alternating-current side of an inverter circuit and performs conversion of the current value to obtain a predetermined conversion value, and a failure detection unit that compares the conversion value obtained by the conversion value calculation unit and a predetermined determination value to be used in failure detection to detect a failure of the alternating-current capacitor.

Abstract: A distributed-power-supply power conversion system includes a plurality of power inverters configured to invert DC power to AC power; and a control device configured to select at least one power inverter from the plurality of power inverters as a power inverter used for testing, and configured to perform an energization test of the power inverter used for testing in a state where an AC side of the power inverter used for testing is disconnected from a system, and is connected to an AC power supply device and to a load bank, and a voltage on the AC side of the power inverter used for testing is established. The distributed-power-supply power conversion system can perform an energization test of a power inverter before a system receives power.

Abstract: An electric power conversion apparatus includes: an electric power conversion circuit that allows a DC terminal to be connected to a DC power source via a DC bus line, and performs at least one of converting DC power of the DC power source into AC power to output, or converting AC power into DC power to output; a DC switch turned on when the electric power conversion circuit performs electric power conversion; an AC switch provided on a side of the AC terminal, and turned on when the electric power conversion circuit performs the electric power conversion; a DC voltmeter that measures a potential at a predetermined portion, on a side of the DC terminal; a ground connection portion that connects the DC bus line and ground potential; and a control circuit connected to the electric power conversion circuit, the DC switch, the AC switch, and the DC voltmeter.

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 control device for a power converter includes a voltage command value limiting unit configured to limit each phase component or an absolute value of a vector of a voltage command value to be equal to or less than a value set in advance. With such a configuration, the control device for the power converter limits each phase component or the absolute value of the vector of the voltage command value to be equal to or less than the value set in advance. Therefore, it is possible to prevent overvoltage of the output from the power converter when impedance rapidly increases on the output side of the power converter.

Abstract: A control device for a power conversion apparatus and a resistor for a power conversion apparatus that can suppress a cross current between a plurality of power converters. A control device for a power conversion apparatus includes, in a state that AC sides of a plurality of power converters are connected in parallel without DC sides of the plurality of power converters being connected in parallel: a voltage recognition unit configured to recognize a voltage to ground on a DC side of a power converter, being an object to be controlled; and a controller configured to control, based on the voltage to ground on the DC side recognized by the voltage recognition unit, a DC voltage of the power converter, being the object to be controlled, such that the voltage to ground on the DC side of the power converter, being the object to be controlled, is further reduced.

Abstract: A controller of a power conversion device including a power converter connected between a direct current (DC) power supply and an alternating current (AC) power supply, includes: a damping control term calculation unit configured to calculate a value of pulsation of a DC voltage applied between the DC power supply and the power converter, or pulsation of a DC current flowing between the DC power supply and the power converter; and a current control unit configured to output, to the power converter, a command value for adjusting the power of the power converter so that a pulsation component corresponding to the pulsation value calculated by the damping control term calculation unit is reduced in accordance with a command value based on the value calculated by the damping control term calculation unit. The power conversion device can reduce resonance without including a damping resistor.

Abstract: A controller for a power conversion system includes a determination unit configured to determine whether a current time is in nighttime in an environment of a power converter that is connected to one or both of a direct-current power supply and an alternating-current power supply, and a control unit configured, in a case that the determination unit determines that the current time is in the nighttime, to maintain a switch in a closed state, the switch being provided between the power converter and one of the alternating-current power supply and the direct-current power supply, and to maintain power consumption by a resistor provided in a main circuit inside a housing of the power converter. The power conversion system can suppress lowering of temperature inside a housing without separately including a space heater.

Abstract: A power conversion device includes a power conversion module, a phase change material, a heat dissipation member, a cooling mechanism, and a controller. A semiconductor switching element and a freewheeling diode configure a power conversion circuit. The phase change material is provided on a principal plane of a casing. The heat dissipation member includes a heat dissipation surface. The heat dissipation surface is overlapped with the principal plane to sandwich the phase change material. The cooling mechanism cools the heat dissipation member. The controller generates a driving signal for driving the power conversion circuit and controls the cooling mechanism. The controller includes a predetermined heating operation. The heating operation may drive the power conversion circuit, in a state that the cooling mechanism is stopped or intermittently operated, such that heat generation occurs in both the semiconductor switching element and the freewheeling diode.

Abstract: A power conversion system includes: a power converter connected between a DC power source and an AC power source; an AC switch connected between the power converter and the AC power source; an AC capacitor connected on the power converter side relative to the AC switch, on an output side of the power converter; and a control device configured to, in a state in which the AC switch is open, recognize a voltage of the AC capacitor and control the power converter to bring an output voltage of the power converter close to a voltage of the AC power source from the voltage of the AC capacitor gradually or in a step-by-step manner, and then close the AC switch. The power conversion system can suppress overcurrent at a time of start-up of a power converter and inrush current at a time of interconnection to an AC power source.

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 control device for a power converter that can suppress oscillation of an output voltage of the power converter. The control device for the power converter includes an overvoltage detector configured to detect an overvoltage on an output side of the power converter and a controller configured to, when the overvoltage on the output side of the power converter is detected by the overvoltage detector, perform gate block after reducing a current command value given to the power converter. With the configuration, when the overvoltage on the output side of the power converter is detected, the control device performs the gate block after reducing the current command value given to the power converter. Accordingly, it is possible to suppress oscillation of an output voltage of the power converter.

Abstract: A multiple power conversion system includes a plurality of first to n-th unit power converters. DC positive sides of the plurality of unit power converters are connected to one another, DC negative sides of the plurality of unit power converters are connected to one another, and n is an integer of two or more. The multiple power conversion system further includes a detector to detect a current flowing through the DC positive side or the DC negative side of a corresponding one of (n?1) or more of the plurality of unit power converters. The multiple power conversion system that can detect a circulating current with a smaller number of current sensors.