Mitsubishi Electric Corporation

Mitsubishi Denki Kabushiki Kaisha

Kikuo Izumi

Tatsuya Okuda

Takuya Kataoka

Takushi Jimichi

Yusuke Higaki

Takahiro Kato

Tsuguhiro Takuno

Akihiko Iwata

Shigeki Harada

Yu Kawai

Takashi Ohsawa

Kenji Fujiwara

Tomoaki Kimura

Takeshi Amimoto

Akiko Tabuchi

Ryoji Tsuruta

Daigo Takemura

Takahiro Urakabe

Hitoshi Kawaguchi

Takaharu Ishibashi

Tomohito Fukuda

Yusuke Kato

Tomoyuki Kawakami

Yuki Itogawa

Yutaka Kuboyama

Masanori Kageyama

Masahiro Sugahara

Naohide Tsuchimoto

Tsutomu Shimazaki

Akihiron Suzuki

Naohisa Kawahara

A DC power supply and distribution system is obtained that improves power distribution efficiency at a low-load factor while suppressing overall upsizing. The DC power supply and distribution system includes a main AC/DC converter and an auxiliary AC/DC converter connected in parallel to the main AC/DC converter and having a rated power capacity smaller than that of the main AC/DC converter, wherein when the absolute value of the DC output power is smaller than the absolute value of a threshold power set smaller than the rated power capacity of the auxiliary AC/DC converter, a first switching command for switching from the first operation mode to the second operation mode is generated for a power conversion unit.

DC power supply and distribution system

The present DC power supply and distribution system comprises: a plurality of power distribution lines each connected to a respective one of a plurality of loads; a first converter to receive an AC voltage from a commercial AC power source, convert the received AC voltage into a plurality of DC voltages and supply each of the plurality of DC voltages to a respective one of the plurality of power distribution lines; a second converter to receive a DC power from a power generating and/or storing source, convert the received DC power into a plurality of DC powers, and supply each of the plurality of DC powers to a respective one of the plurality of power distribution lines; and a controller to enhance the second converter in efficiency by controlling the first converter so that a ratio of the plurality of DC voltages is a predetermined first ratio.

Direct-current power supply and distribution system

An insulating transformer includes a plurality of sub-insulating transformers connected in series. Polarity directions of all sub-windings are identical. When a current I flows from a first main terminal to a third main terminal through the first sub-winding, an interphase capacitance, and the second sub-winding, excitation inductance of the first sub-winding and excitation inductance of the second sub-winding are configured to have opposite polarities.

Insulating transformer and power conversion device equipped with same

A power conversion device includes an inverter that generates an inverter voltage, a filter that receives the inverter voltage and outputs an output voltage, a detector that detects a DC component of the output voltage, a feedback controller that receives an AC voltage command and the DC component and determines an inverter voltage command such that the DC component is equal to a target value which is zero or a value corresponding to an offset error of the detector, and a PWM controller that receives the inverter voltage command and performs pulse width modulation control of the inverter. The feedback controller computes a compensation amount for compensating for the DC component and determines, as the inverter voltage command, the AC voltage command on which a product of an absolute value of a sine wave synchronized with a period of the AC voltage command and the compensation amount is superimposed.

Power conversion device

A power supply system includes a plurality of power conversion devices connected in parallel with each other, a load state detector to detect an operating state of a load connected to the DC system, and a command generator to generate a distribution voltage command Vref. Each of the power conversion devices includes a DC voltage controller to generate an output power command Pdc_ref based on a voltage of the DC system and the distribution voltage command Vref, and an AC/DC converter to convert AC power received from the main power source based on the output power command Pdc_ref and output the converted power to the DC system. The command generator generates the distribution voltage command Vref such that loss of the load connected to the DC system is reduced, based on a detection result of the load state detector.

Power supply system including a plurality of power conversion devices to supply AC or DC power

The present DC power supply and distribution system includes a plurality of distribution lines provided respectively corresponding to a plurality of loads, a first converter to convert an AC voltage from a commercial AC power source into a plurality of DC voltages and supply the DC voltages respectively to the distribution lines, a second converter to convert a DC power from a power generation and storage source into a plurality of DC powers and supply the DC powers respectively to the distribution lines, and a power controller to control the DC powers such that the efficiency of the first converter is increased, based on information related to the efficiency of the second converter.

A power supply system includes a power converter, a load state detector, and a controller. The power converter converts AC power received from the main power source into DC power with a voltage in accordance with a distribution voltage command value Vref and supplies the DC power to the load. The load state detector detects an operating state of the load. The controller operates in an operation mode selected from among a plurality of operation modes and generates the distribution voltage command value Vref. The operation modes include a distribution voltage control mode in which the distribution voltage command value Vref is generated based on load operating information detected by the load state detector and a distribution voltage fixed mode in which a predetermined setting value or an external command value acquired from an external device is set as the distribution voltage command value Vref.

Multi-mode power supply system

An object is to obtain a power conversion device that can stabilize output voltage to a DC load. A power conversion device includes an AC/DC conversion unit having a power conversion circuit composed of a plurality of first semiconductor switching elements connected in a full-bridge form, and a full-bridge chopper circuit unit having a full-bridge chopper circuit composed of a plurality of second semiconductor switching elements connected in a full-bridge form, and connected to a positive terminal and a negative terminal. A neutral point of an AC filter capacitor unit and a neutral point of a DC filter capacitor unit are connected via a neutral point line.

AC-to-DC power converter which removed a common mode component form the output current

A power conversion device converts a direct-current power on the DC side of the power conversion device to an alternating-current power by an inverter circuit having a plurality of semiconductor switching elements, and outputs the AC power from the AC side of the power conversion device. A current detector detects a reactor current output from the inverter circuit. As overcurrent detector detects overcurrent in a control mode in which the reactor current is caused to follow a reactor current command value, control circuit starts an overcurrent mode in which a time period where the reactor current monotonically decreases is provided. In the overcurrent mode, whether to switch the overcurrent mode to the normal control mode is determined based on the reactor current or in accordance with a timing corresponding to a zero-cross point of a voltage or current on the AC side.

A DC supply and distribution system includes an AC-DC converter for converting an AC power input from an AC power line to DC powers having a plurality of different voltages and outputting the converted DC powers; and a voltage controller for controlling the different voltages of the DC powers to be output from the AC-DC converter. The output DC powers are distributed to the plurality of loads through a plurality of respective DC lines connected from the output terminals of the AC-DC converter.

The power conversion device includes common DC buses, AC buses, DC connection terminals, AC connection terminals, N pairs of distributed power supply connection terminals, N DC/DC converters for transferring power between the common DC buses and the distributed power supply connection terminals, M DC/AC converters for transferring power between the AC buses and the common DC buses, and a control unit for controlling each converter on the basis of a high-order control command. The DC connection terminals are connected to the common DC buses and connected to an external DC power distribution grid, the AC connection terminals are connected to the AC buses and connected to an external AC power distribution grid, and the distributed power supply connection terminals are connected to the DC/DC converters and connected to external DC distributed power supplies.

A controller of each power conversion device in a power conversion system controls a switching element unit, based on a detected value of reactor current flowing through a filter reactor, a detected value of output voltage output between the terminals of a filter capacitor, and a detected value of output current flowing through an output reactor. The controller generates a voltage command based on the output current and the output voltage and generates a correction amount of the voltage command based on the output current in which a reference frequency component is removed. The controller generates a current command based on the addition value of the voltage command and the correction amount and controls the switching element unit such that the reactor current matches the current command.

Power conversion device and power conversion system

A power conversion device includes a power converter connected to an electrical storage device that stores DC power, and having a function to convert the DC power stored in the electrical storage device into AC power, and also having a function to output the AC power to one or both of a customer load and a power system; a detection unit that detects voltage and current at a first point on a power line that connects the power converter with the power system; and a control unit that generates a drive command for controlling the power converter based on the voltage and the current detected by the detection unit. The customer load is connected to a second point, on the power line, between the power converter and the first point. The power converter operates on the basis of the drive command generated by the control unit.

A power system and a power conversion device are interconnected via an interconnection switch. A user load is provided between the power conversion device and the interconnection switch. In parallel with the interconnection switch, a series circuit composed of a load disconnection switch and a voltage maintenance load for maintaining voltage of the user load at the time of system momentary power interruption is connected. Control is performed such that, when momentary power interruption occurs, the interconnection switch is turned off and the power system and the power conversion device are connected via the voltage maintenance load, and at the time of recovery from the momentary power interruption, the interconnection switch is turned on, further the power system and the power conversion device are connected.

Power conversion system for power system interconnection

A power conversion device includes: a power conversion unit composed of a power conversion circuit having switching elements, an output current measurement unit, an output voltage measurement unit, and reactor; a voltage command generating unit for generating a voltage command; a dead time correction unit for calculating a dead time correction amount for correcting voltage error, between the voltage command and output voltage, caused due to dead time; and a PWM signal generating unit for generating switching signals according to the voltage command and the dead time correction amount, wherein the dead time correction unit calculates the dead time correction amount from the voltage command, the measured output voltage, and the measured output current.

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Tokyo, Japan

Kikuo Izumi