Toshiba Mitsubishi-electric Industrial Systems Corporation

Mitsubishi Electric Corporation

Mitsubishi Denki Kabushiki Kaisha

Tmeic Corporation

Taichiro Tsuchiya

Jumpei Isozaki

Toshiyuki Fujii

Ryosuke Uda

Kaho Mukunoki

Hisanori Taguchi

Takushi Jimichi

Akihiro Matsuda

Ryota Okuyama

Yasuhiro Shinomiya

Kimiyuki Koyanagi

Akito Nakayama

Akihiko Iwata

Osamu Mori

Hiroaki Yamaguchi

Tatsuya Okuda

Hideo Okayama

Yuki Ishii

Sadao Funahashi

Tomoyuki Kawakami

Fumio Mizohata

Kenshi Takao

Horst Gruening

Naoki Yonemura

Shohei Harada

Takayuki Yachida

Yuhei Wada

First to third capacitors each have an identical shape of a rectangular parallelepiped. The rectangular parallelepiped has a first surface with a first side and a second side, a second surface with the second side and a third side, and a third surface with the third side and the first side. The first side has a length not less than twice and less than three times a length of the third side. The first and second capacitors are arranged such that the first surfaces thereof are perpendicular to an installation surface, the first surfaces face each other, and the second surfaces are horizontal to the installation surface. The third capacitor is arranged such that the first surface thereof faces the second surfaces of the first and second capacitors and the third surface thereof is flush with the third surfaces of the first and second capacitors.

Power conversion apparatus

A main circuit power supply device includes: a plurality of voltage-division power storage elements connected in series; voltage adjustment circuits for adjusting each of voltages of the plurality of voltage-division power storage elements through mutual transfer of power between the plurality of voltage-division power storage elements; and at least one DC/DC converter which is connected to at least one of the voltage-division power storage elements and supplies a control power source to a main circuit control circuitry to control a main circuit.

Power conversion device

Each of a plurality of unit converters includes: a main circuit; a control circuit that controls the plurality of switching elements according to a control signal received from the controller; a power supply that lowers a voltage of a first capacitor to generate a power supply voltage and supplies the power supply voltage to the control circuit; and a current-limiting resistance circuit having a variable resistance value and disposed between the main circuit and the power supply. The power supply includes a second capacitor, an overcharge suppression circuit, a power supply circuit, and a controller. The controller includes: an overcharge suppression control circuit that controls the overcharge suppression circuit in accordance with a magnitude of a voltage of the second capacitor; and a resistance switching circuit that changes a resistance value of the current-limiting resistance circuit in accordance with a magnitude of a voltage of the first capacitor.

Current limiting circuit for multilevel power converter cell

A power supply includes a second capacitor, an overcharge suppression circuit, a power supply circuit, and a controller. The controller includes: an overcharge suppression control circuit that controls the overcharge suppression circuit in accordance with a magnitude of a voltage of the second capacitor; and a resistance switching circuit that changes a resistance value of the current-limiting resistance circuit depending on whether a gate block state occurs or not and in accordance with a magnitude of the voltage of the first capacitor. In the gate block state, each of the switching elements is fixed in a non-conductive state.

A master converter and a plurality of slave converters each have an input connected to an associated one of a plurality of power storage elements, respectively, and an output connected to an output terminal in parallel. The master converter converts the voltage of the associated capacitor based on a duty ratio for matching an output voltage to a voltage command value, outputs the converted voltage to the output terminal, and transmits a control signal indicative of the duty ratio to the plurality of slave converters via a signal insulation unit. Each of the plurality of slave converters converts the voltage of the associated capacitor in response to the control signal transmitted via the signal insulation unit and outputs the converted voltage to the output terminal. A correction means is configured to correct at least the duty ratio in the master converter such that the duty ratio in the master converter matches the duty ratio in each of the plurality of slave converters.

Self-power feed circuit and power conversion device

A power supply circuit is configured to convert a voltage of a second electricity storage element into a power supply voltage for a driving circuit, and a voltage detector is configured to detect the voltage of the second electricity storage element. A unit converter includes a first resistor connected to the second electricity storage element electrically in series between the terminals of a first electricity storage element, and a second resistor and a first switch connected electrically in series between the terminals of the second electricity storage element. The power supply circuit is configured to generate a control signal for controlling the first switch on and off based on the detection value from the voltage detector. The power supply circuit is further configured to sense an overloaded state of the second resistor based on the control signal.

A control unit activates a power supply circuit when an input voltage becomes equal to or greater than a first threshold value. The control unit brings a switch into a conductive state when the input voltage becomes equal to or greater than a second threshold value and brings the switch into a non-conductive state when the input voltage becomes equal to or less than a third threshold value. The control unit deactivates the power supply circuit when the input voltage becomes equal to or less than a fourth threshold value. Based on the number of times that the input voltage becomes equal to or greater than the second threshold value after the power supply circuit is activated, the control unit further enables a latch function for holding the power supply circuit in a deactivated state.

In a power conversion device, an inverter () of each of three arms (Ato A) is controlled such that circulating current (Iz) of three arms (Ato A) follows a reference (Izrt) in a test period (times tto t) in which a power system () is cut off from the three arms (Ato A), and whether the power conversion device is normal is determined based on circulating current (Iz) in the test period. Whether the power conversion device is normal therefore can be determined without affecting the power system ().

Power conversion device and test method thereof

A control device generates a voltage command value for controlling a current flowing between a three-phase AC power supply and a power converter such that a full voltage representative value representing voltage values of all power storage devices agrees with a DC voltage command value. The control device generates a zero-phase voltage command value for controlling a circulating current flowing in a delta connection such that the voltage values of the power storage devices are balanced among first to third arms. The control device combines the voltage command value and the zero-phase current command value to generate an output voltage command value for controlling an output voltage of each unit converter. The control device removes a control amount of the full voltage representative value from a computation of the zero-phase voltage command value to cause output current control and circulating current control not to interfere with each other.

Power conversion apparatus for interconnection with a three-phrase ac power supply

In the present power conversion device, when a fault occurs in a power system () and DC voltage (VDC) of a capacitor () included in a unit converter () exceeds a protection level (VH), the operation of an inverter () is stopped. When the DC voltage (VDC) decreases to a recovery level (V1) or lower, DC voltage control of the inverter () is resumed to quickly decrease the DC voltage (VDC). When the DC voltage (VDC) decreases to a recovery level (V2) or lower, reactive power control of the inverter () is resumed. Thus, even when a fault occurs in the power system (), the operation of the inverter () can be quickly resumed.

A power converter is electrically connected with an AC power supply via a switch, and is configured with a plurality of unit converters () connected in series. A drive circuit () drives a plurality of switching elements (to) of a main circuit (). An interface circuit () outputs a detection value of a voltage sensor () to a control device (). If a bypass switch () is turned off when the power converter is activated, each of the plurality of unit converters () charges a capacitor () using power supplied from the AC power supply. When the power converter is activated, a power supply () supplies a power supply voltage to the voltage sensor () and the interface circuit (), prior to the drive circuit (). The control device () turns off the switch when the detection value of the voltage sensor () of at least one of the plurality of unit converters () is more than or equal to a predetermined value.

Since a power converter including a modular multilevel converter uses a large number of cells each combining a plurality of switching elements and a DC capacitor, there is a problem of conduction loss due to the switching elements. The conduction loss is reduced by connecting a bypass circuit between terminals of each of the cells, controlling to open and close the switching element, and controlling to short-circuit the bypass circuit connected to the cell controlled to output zero voltage.

Power converter

An MMC includes arms configured with one unit converter or a plurality of cells connected in series. The main circuit of the cell includes a switching element and a DC capacitor. The power supply of the cell lowers voltage of the DC capacitor to generate power supply voltage to be supplied to the control circuit of the cell. The power supply includes a power supply circuit configured to convert input voltage provided between first and second input terminals from the DC capacitor into power supply voltage, a thyristor connected between the first and second input terminals electrically in parallel with the power supply circuit, a current-limiting resistor connected between terminals of the DC capacitor electrically in series with the thyristor, and a control unit configured to fire the thyristor when input voltage applied to the power supply circuit exceeds a threshold voltage.

A power conversion device in which a plurality of converter cells are connected in series with one another. The converter cells each include two or more semiconductor devices, an energy storage element and a bypass element including a constituent element for setting the bypass element to be close-circuited by detecting abnormality of a converter cell, and including a constituent element for controlling, among the semiconductor devices, a semiconductor device connected in parallel with the bypass element to set in a turn-on state, at the same time when the bypass element is set close-circuited or in advance of its close circuit.

An MMC includes arms each configured with one unit converter or a plurality of cells connected in series. A control circuit of the cell transmits a voltage detected value of a DC capacitor to a control device and controls on/off of a switching element in accordance with a control signal received from the control device. When the voltage detected value of at least one cell exceeds a first threshold voltage, the control device transmits a gate block signal to the control circuit of each cell. The control circuit of each cell autonomously fixes the switching element of its own main circuit to an off state and short-circuits the output terminals of the main circuit, irrespective of the control signal, when its own voltage detected value exceeds a second threshold voltage higher than the first threshold voltage.

Growing community of inventors

Chuo-ku, Japan

Taichiro Tsuchiya