JP6071859B2 - Power converter - Google Patents

Description

  The present invention relates to a power conversion device.

  In general, an MMC (modular multilevel converter) is known as a power converter. The MMC is a power conversion device including a plurality of chopper cells (unit converters). The chopper cell includes a switching element such as an IGBT (insulated gate bipolar transistor) and a capacitor.

  On the other hand, a power conversion circuit having a distributed energy storage device in which protection components are electrically connected in parallel to the connection terminals of each subsystem and can operate continuously in a redundant manner in the event of a failure is disclosed. (See Patent Document 1). Further, an apparatus is disclosed in which each submodule is provided with a vacuum switch tube for short-circuiting the submodule (see Patent Document 2). Further, a bridging unit for short-circuiting conversion cells of a multilevel converter is disclosed (see Patent Document 3).

JP-T 2009-506736 Special table 2010-524426 JP 2011-205887 A

  However, if an abnormality occurs in the converter constituting the MMC and the gate power supply disappears, the switching element cannot be turned on, and the DC voltage of the capacitor cannot be controlled. When the DC voltage cannot be controlled, the voltage determined in the current direction is output from the converter, so that the controllability of the output voltage of the MMC is degraded. In this case, there is a possibility that the operation of the MMC cannot be continued.

  Then, the objective of this invention is providing the power converter device which can be drive | operated even if the gate power supply of a converter lose | disappears.

  A power converter according to an aspect of the present invention provides a gate signal to a plurality of switching elements connected in series and an inter-terminal switching element provided between terminals among the plurality of switching elements in the event of an abnormality. DC power supply, abnormality detection means for detecting an abnormality, and operation means for turning on the inter-terminal switching element by the DC power supply when abnormality is detected by the abnormality detection means.

  According to the present invention, there is provided a power conversion device capable of continuing operation even when the gate power supply of the converter disappears.

The block diagram which shows the structure of the unit converter which concerns on the 1st Embodiment of this invention. The block diagram which shows the structure of the converter which concerns on the 2nd Embodiment of this invention. The block diagram which shows the structure of the converter which concerns on the 3rd Embodiment of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

(First embodiment)
FIG. 1 is a configuration diagram showing a configuration of a unit converter 1 according to the first embodiment of the present invention. In addition, the same code | symbol is attached | subjected to the same part in drawing, the detailed description is abbreviate | omitted, and a different part is mainly described.

  The unit converter 1 is a minimum unit power converter (chopper cell) constituting an MMC (power converter). The MMC is configured by connecting a plurality of unit converters 1 in series (cascade connection). The unit converter 1 includes a DC capacitor 2, a DC power supply 3, a switch 4, a switch control unit 5, two switching elements 11 and 12, two diodes 13 and 14, and two gate drive circuits 15 and 16.

  The upper side (positive electrode side) switching element 11 and the lower side (negative electrode side) switching element 12 are connected in series. A connection point between the two switching elements 11 and 12 becomes one terminal T1 of the unit converter 1. The negative electrode side (emitter side) of the lower switching element 12 is another terminal T2 of the unit converter 1. The switching elements 11 and 12 are, for example, IGBTs (insulated gate bipolar transistors). Power conversion is performed by driving (switching) the switching elements 11 and 12.

  The two diodes 13 and 14 are connected to the two switching elements 11 and 12 in antiparallel. The DC capacitor 2 is connected in parallel with the two switching elements 11 and 12 connected in series.

  The two gate drive circuits 15 and 16 are provided corresponding to the two switching elements 11 and 12, respectively. The gate drive circuits 15 and 16 drive the switching elements 11 and 12 by outputting a gate voltage (gate signal), respectively. The gate voltage is output from the gate power supply. The gate power supply may be a main circuit power supply system that supplies power from the main circuit, or a system that supplies power from a low-voltage power supply via an insulation transformer. The gate drive circuit 16 provided in the lower switching element 12 outputs the input gate signal to the switch control unit 5. In addition, the gate drive circuits 15 and 16 may monitor the states of the switching elements 11 and 12, respectively, and output an abnormality detection signal to the switch control unit 5 when an abnormality is detected.

  The DC power source 3 is provided in the switching element 12 provided between the two terminals T1 and T2 of the unit converter 1. In FIG. 1, the DC power supply 3 is connected via a switch 4 between the gate terminal and the emitter terminal of the lower switching element 12. The DC power supply 3 applies a gate voltage for turning on the gate terminal of the switching element 12 when the gate power supply is lost. Here, the DC power supply 3 is a secondary battery, but may be a capacitor or a battery other than the secondary battery.

  The switch control unit 5 is connected to a gate drive circuit 16 provided in the lower switching element 12 through a transmission path for transmitting and receiving data. The switch control unit 5 controls the operation of the switch 4 based on the data received from the gate drive circuit 16. Note that the switch control unit 5 may receive information from other than the gate drive circuit 16 in order to control the switch 4. For example, the switch control unit 5 may receive information for monitoring the state of charge (SOC) of the DC power supply 3 or information for monitoring the voltage of the DC capacitor 2. Based on such information, the switch control unit 5 detects an abnormality of the unit converter 1 and operates the switch 4. When the switch controller 5 detects an abnormality, the switch 4 is turned on. Here, an abnormality is mainly assumed when the gate power supply is lost, but the switch control unit 5 may turn on the switch 4 by any other abnormality.

  The switch 4 is connected in series with the DC power supply 3. The switch 4 is a break contact (normally on, b contact) switch. The switch 4 is operated by a control command from the switch control unit 5. When the gate power source is not established or when the DC power source 3 is not sufficiently charged until the switching element 12 can be turned on as the gate power source, the switch 4 is turned on. When the gate power supply is established and the DC power supply 3 is not sufficiently charged, the DC power supply 3 is charged by the gate power supply. When the DC power supply 3 is charged, the switch 4 is turned off. When an abnormality such as loss of the gate power supply occurs, the switch 4 is turned on so that a gate voltage for turning on the switching element 12 is applied from the DC power supply 3 to the gate terminal of the switching element 12.

  Next, the operation of the unit converter 1 will be described.

  Since the switch 4 is a break contact, it is turned on immediately after the unit converter 1 is activated. At this time, the DC power supply 3 is charged by the gate power supply. If charging of the DC power supply 3 is completed and no abnormality has occurred in the unit converter 1, the switch control unit 5 turns off the switch 4. Thus, at the normal time, the unit converter 1 operates with the switch 4 turned off.

  When an abnormality that causes the gate power supply to be lost occurs in the unit converter 1, the switch control unit 5 detects this abnormality and turns on the switch 4. When the switch 4 is turned on, a gate voltage is applied from the DC power source 3 to the switching element 12. Thereby, the switching element 12 is forcibly turned on. When the switching element 12 is turned on, the terminals T1 and T2 of the unit converter 1 are short-circuited. The unit converter 1 in which the terminals T1 and T2 are short-circuited only passes the MMC converter current. Thereby, the unit converter 1 in which the abnormality has occurred is substantially excluded, and the operation is continued by the MMC configured by the remaining unit converters 1.

  According to the present embodiment, when an abnormality occurs, the terminals T1 and T2 of the unit converter 1 can be short-circuited by turning on the switching element 12 provided between the terminals T1 and T2. Thereby, it is possible to continue the operation with the MMC (power conversion device) configured by other unit converters 1 excluding the unit converter 1 in which an abnormality has occurred.

  Even if the gate power supply is lost, the DC power supply 3 is provided separately from the normal gate power supply. Therefore, the switching element 12 is turned on and the terminals T1 and T2 of the unit converter 1 are short-circuited. can do.

(Second Embodiment)
FIG. 2 is a configuration diagram showing the configuration of the converter 1A according to the second embodiment of the present invention.

  The converter 1A is a power conversion device configured as one submodule by two unit converters (chopper cells) 1Aa and 1Ab. An MMC is configured by connecting a plurality of converters 1A in series (cascade connection).

  The unit converter 1Aa on the upper side (positive electrode side) has the same configuration as the unit converter 1 according to the first embodiment shown in FIG. Specifically, in the unit converter 1Aa, a DC capacitor 2a, a DC power supply 3a, a switch 4a, a switch control unit 5a, two switching elements 11a and 12a, two diodes 13a and 14a, and two gate drive circuits 15a, Reference numeral 16a denotes a DC capacitor 2, a DC power supply 3, a switch 4, a switch control unit 5, two switching elements 11 and 12, two diodes 13 and 14 in the unit converter 1 according to the first embodiment, and This corresponds to the two gate drive circuits 15 and 16.

  The unit converter 1Ab on the lower side (negative electrode side) is the same as the unit converter 1 according to the first embodiment shown in FIG. 1 except that the DC power source 3, the switch 4, and the switch control unit 5 are replaced with the upper switching element 11. It is the structure which was provided in the lower side switching element 12. Specifically, in the unit converter 1Ab, a DC capacitor 2b, a DC power supply 3b, a switch 4b, a switch control unit 5b, two switching elements 11b and 12b, two diodes 13b and 14b, and two gate drive circuits 15b, 16b are respectively the DC capacitor 2, the DC power supply 3, the switch 4, the switch control unit 5, the two switching elements 11 and 12, the two diodes 13 and 14, and the unit converter 1 according to the first embodiment. This corresponds to the two gate drive circuits 15 and 16.

  The upper side of the switching elements 11b and 12b connected in series of the lower unit converter 1Ab is connected to the lower side of the switching elements 11a and 12a connected in series of the upper unit converter 1Aa. The connection point of the two switching elements 11a and 12a of the upper unit converter 1Aa and the connection point of the two switching elements 11b and 12b of the lower unit converter 1Ab are the two terminals T1A and T2A of the converter 1A. .

  When an abnormality that causes loss of the gate power supply occurs in the converter 1A, the switch controllers 5a and 5b of the two unit converters 1Aa and 1Ab turn on the switches 4a and 4b, respectively. When the switches 4a and 4b are turned on, the two switching elements 12a and 11b between the two terminals T1A and T2A of the converter 1A are turned on by the gate voltages output from the two DC power sources 3a and 3b, respectively. . As a result, the two terminals T1A and T2A of the converter 1A are short-circuited. Note that the two switch control units 5a and 5b can share and detect the detected faults, and may be linked so that the two switches 4a and 4b are both turned on. In other respects, the two unit converters 1Aa and 1Ab of the converter 1A operate in the same manner as the unit converter 1 according to the first embodiment.

  According to the present embodiment, in the converter 1A configured as a submodule, the same effects as those of the first embodiment can be obtained.

(Third embodiment)
FIG. 3 is a configuration diagram showing a configuration of a converter 1B according to the third embodiment of the present invention.

  The two unit converters 1Ba and 1Bb constituting the converter 1B correspond to the two unit converters 1Aa and 1Ab according to the second embodiment shown in FIG. In the converter 1B, the two DC power sources 3a and 3b according to the second embodiment are changed to one DC power source 3B, and one DC power source 3B is connected to two of the converters 1B via two switches 4Ba and 4Bb, respectively. In this configuration, two switching elements 12a and 11b between the terminals T1A and T2A are connected. The DC power supply 3B may be provided in any of the two unit converters 1Ba and 1Bb, or may be provided outside the two unit converters 1Ba and 1Bb. Other points are the same as in the second embodiment.

  According to the present embodiment, in addition to the operational effects of the second embodiment, the two DC power supplies 3a and 3b are replaced with one DC power supply 3B, thereby reducing the size and manufacturing cost compared to the second embodiment. Can be reduced.

  In each embodiment, converters 1 to 1B are not limited to the circuit configuration described, and may be implemented. For example, a circuit in which three or more switching elements are connected in series to the unit converter may be used, or any number of DC capacitors may be provided. When configured as a submodule, any number of unit converters may be connected. In any converter, the switching element between the two terminals of the converter is provided with a DC power supply for turning on in the event of an abnormality, and in the event of an abnormality, the gate signal is given to the switching element by the DC power supply, The two terminals of the resulting converter can be short-circuited. Thereby, the power converter device comprised with a converter can exclude a converter in which abnormality has occurred and can continue operation. Therefore, the same effect as each embodiment can be obtained.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. Moreover, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  DESCRIPTION OF SYMBOLS 1 ... Unit converter, 2 ... DC capacitor, 3 ... DC power supply, 4 ... Switch, 5 ... Switch control part, 11, 12 ... Switching element, 13, 14 ... Diode, 15, 16 ... Gate drive circuit, T1, T2 ... terminal

Claims (7)

A plurality of switching elements connected in series;
DC power supply for giving a gate signal to the switching element between the terminals provided between the terminals among the plurality of switching elements at the time of an abnormality,
An anomaly detecting means for detecting an anomaly;
The power conversion apparatus comprising: an operation unit that turns on the inter-terminal switching element by the DC power supply when an abnormality is detected by the abnormality detection unit. A power converter in which a plurality of converters are connected in series,
The converter is
A plurality of switching elements connected in series;
DC power supply for giving a gate signal to the switching element between the terminals provided between the terminals among the plurality of switching elements at the time of an abnormality,
An anomaly detecting means for detecting an anomaly;
The power conversion apparatus comprising: an operation unit that turns on the inter-terminal switching element by the DC power supply when an abnormality is detected by the abnormality detection unit. The power converter according to claim 1, wherein the abnormality detection unit detects that a gate power source for driving the plurality of switching elements is lost as an abnormality. A switch for connecting and disconnecting an electrical path connecting the DC power supply and the inter-terminal switching element;
The power converter according to any one of claims 1 to 3, wherein the operation unit operates the switch. The power converter according to claim 4, wherein the switch is a break contact that is turned on when an abnormality occurs. Detect anomalies,
A power conversion device comprising: turning on a switching element provided between terminals among a plurality of switching elements connected in series by a DC power source for providing a gate signal when an abnormality is detected when an abnormality is detected Control method. A method for controlling a power converter in which a plurality of converters are connected in series,
The converter is
Detect anomalies,
A power conversion device comprising: turning on a switching element provided between terminals among a plurality of switching elements connected in series by a DC power source for providing a gate signal when an abnormality is detected when an abnormality is detected Control method.

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