JP6111031B2 - Self-excited power converter - Google Patents

Description

  The present invention relates to a self-excited power conversion device.

  In general, an MMC (modular multilevel converter) is known as a self-excited power converter. The MMC is a power conversion device configured with a plurality of cells (unit converters). The MMC is controlled by a gate pulse (gate signal) input to each cell. An optical fiber cable is used for transmission of the gate pulse. In order to shorten the optical fiber cable, it is disclosed that each cell is daisy chain connected with an optical fiber cable and an optical serial signal is transmitted to each cell (for example, see Patent Document 1).

JP 2011-24393 A

  However, when the gate signal is serially communicated to a plurality of cells, if an abnormality occurs in the transmission line, the trouble of continued operation of the self-excited power conversion device increases. For example, when the gate signal is serially communicated to all the cells with one line, if this one line becomes abnormal, it becomes impossible to communicate with all the cells. Therefore, the operation of the self-excited power converter cannot be continued.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a self-excited power conversion device that serially communicates with a plurality of unit converters and has high continuity of operation against a line abnormality for serial communication.

Self-commutated power conversion apparatus according to the aspect of the present invention is composed of a plurality of unit converters each phase of the positive and negative electrodes of the power conversion circuit are connected in series for converting DC power to three-phase AC power A plurality of arms and the plurality of unit converters constituting each arm are divided into a minimum number necessary for continued operation, and a plurality of units converters connected for serial communication for each necessary minimum number Transmission line.

  According to the present invention, it is possible to provide a self-excited power conversion device that performs serial communication with a plurality of unit converters and has high continuity of operation against an abnormality in a line for serial communication.

The block diagram which shows the structure of the self-excitation power converter device which concerns on the 1st Embodiment of this invention. The circuit diagram shown about the circuit of the cell concerning a 1st embodiment. FIG. 3 is a structural diagram simply showing the structure of data transmitted to each cell by serial communication according to the first embodiment. The block diagram which shows the structure of the self-excited power converter device which concerns on the 2nd 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 self-excited power conversion device 1 according to a 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. In the following embodiments, the same description is omitted.

  The self-excited power converter 1 includes a DC power source 2, a control device 3, six arms 4up, 4um, 4vp, 4vm, 4wp, 4wm, three-phase reactors 5u, 5v, 5w, and a three-phase interconnected reactor. 6u, 6v, 6w are provided. The self-excited power conversion device 1 supplies three-phase AC power to AC systems 7u, 7v, and 7w having an AC power source and an AC load.

  The DC power supply 2 supplies the generated DC power to a power conversion circuit composed of six arms 4up to 4wm. The DC power source 2 is not limited to a device that generates power by itself, but may be a converter or a secondary battery that converts AC power into DC power.

  The control device 3 includes cells (unit converters) CL11 to CL constituting the arms 4up to 4wm via the transmission lines L11, L12, L21, L22, L31, L32, L41, L42, L51, L52, L61, and L62. Serial communication with CL68. The transmission lines L11 to L62 are configured by optical fiber cables and repeaters. The control device 3 controls the power conversion circuit by transmitting a gate signal to each of the cells CL11 to CL68 by serial communication.

  The six arms 4up to 4wm constitute a power conversion circuit that converts DC power into three-phase AC power. The arm 4up is composed of eight series-connected cells CL11, CL12, CL13, CL14, CL15, CL16, CL17, and CL18 that constitute the positive phase side of the U phase of the power conversion circuit. The arm 4um is composed of eight cells CL21, CL22, CL23, CL24, CL25, CL26, CL27, and CL28 connected in series to form the negative phase side of the U phase of the power conversion circuit. The arm 4vp is composed of eight serially connected cells CL31, CL32, CL33, CL34, CL35, CL36, CL37, and CL38, which constitute the positive phase side of the V phase of the power conversion circuit. The arm 4vm comprises eight series-connected cells CL41, CL42, CL43, CL44, CL45, CL46, CL47, and CL48, which constitute the negative phase side of the V phase of the power conversion circuit. The arm 4wp is composed of eight cells CL51, CL52, CL53, CL54, CL55, CL56, CL57, and CL58 connected in series to constitute the positive side of the W phase of the power conversion circuit. The arm 4wm is composed of eight series-connected cells CL61, CL62, CL63, CL64, CL65, CL66, CL67, and CL68, which constitute the negative side of the W phase of the power conversion circuit.

  Each arm 4up-4wm can output a normal voltage if at least four cells CL11-CL68 operate normally. The normal voltage is, for example, a rated voltage of the self-excited power conversion device 1 or a voltage requested from the AC systems 7u, 7v, 7w.

  The transmission line L11 daisy-chains four positive-side cells CL11 to CL14 constituting the U-phase positive-side arm 4up. The transmission line L12 daisy-chains four negative-side cells CL15 to CL18 constituting the U-phase positive-side arm 4up. The transmission line L21 daisy chain connects the four positive-side cells CL21 to CL24 constituting the U-phase negative-side arm 4um. The transmission line L22 daisy chain connects the four negative-side cells CL25 to CL28 constituting the U-phase negative-side arm 4um.

  The transmission line L31 daisy-chains four positive-side cells CL31 to CL34 constituting the V-phase positive-side arm 4vp. The transmission line L32 daisy-chains four negative-side cells CL35 to CL38 constituting the V-phase positive-side arm 4vp. The transmission line L41 daisy-chains the four positive-side cells CL41 to CL44 constituting the V-phase negative-side arm 4vm. The transmission line L42 daisy-chains four negative-side cells CL45 to CL48 that constitute the V-phase negative-side arm 4vm.

  The transmission line L51 daisy-chains four positive-side cells CL51 to CL54 constituting the W-phase positive-side arm 4wp. The transmission line L52 daisy chain-connects four negative-side cells CL55 to CL58 constituting the W-phase positive-side arm 4wp. The transmission line L61 daisy-chains four positive-side cells CL61 to CL64 that constitute the W-phase negative-side arm 4wm. The transmission line L62 daisy-chains the four negative-side cells CL65 to CL68 constituting the W-phase negative-side arm 4wm.

  FIG. 2 is a circuit diagram showing a circuit of the cell CL according to the present embodiment. The configuration of all the cells CL11 to CL68 is the same as that of the cell CL shown in FIG.

  Cell CL is a double star chopper. The cell CL is a circuit composed of two switching elements SW1 and SW2, two antiparallel diodes D1 and D2, and a capacitor CD. The cell CL is a gate signal transmitted from the control device 3 and is driven when the two switching elements SW1 and SW2 are switched.

  The two switching elements SW1 and SW2 are connected in series. Antiparallel diodes D1 and D2 are connected to the two switching elements SW1 and SW2, respectively. The capacitor CD is connected in parallel with the two switching elements SW1 and SW2 connected in series. A connection point between the two switching elements SW1 and SW2 serves as a positive terminal of the cell CL. The positive terminal of the cell CL is connected to the negative terminal of the cell CL adjacent to the positive electrode side or the positive electrode side of the DC power source 2. A terminal (emitter) on the negative electrode side of the switching element SW2 located on the negative electrode side becomes a negative electrode terminal of the cell CL. The negative terminal of the cell CL is connected to the positive terminal of the cell CL adjacent to the negative electrode side or the negative electrode side of the DC power source 2.

  The U-phase reactor 5u is provided between the U-phase positive-side arm 4up and the U-phase negative-side arm 4um. An intermediate point of reactor 5u is a U-phase output point of AC power. The intermediate point of reactor 5u is connected to the U phase of AC system 7u via interconnection reactor 6u. Reactor 5u is provided to suppress a direct current component of the circulating current flowing through U-phase positive arm 4up and U-phase negative arm 4um.

  The V-phase reactor 5v is provided between the V-phase positive arm 4vp and the V-phase negative arm 4vm. An intermediate point of reactor 5v is a V-phase output point of AC power. The midpoint of reactor 5v is connected to the V phase of AC system 7v via interconnection reactor 6v. Reactor 5v is provided to suppress a direct current component of the circulating current flowing through arm 4vp on the positive side of V phase and arm 4vm on the negative side of V phase.

  The W-phase reactor 5w is provided between the W-phase positive arm 4wp and the W-phase negative arm 4wm. An intermediate point of reactor 5w is a W-phase output point of AC power. The midpoint of reactor 5w is connected to the W phase of AC system 7w via interconnection reactor 6w. Reactor 5w is provided to suppress the DC component of the circulating current flowing through W-phase positive arm 4wp and W-phase negative arm 4wm.

  The interconnecting reactors 6u, 6v, 6w are reactors provided for interconnecting the AC systems 7u, 7v, 7w. The U-phase interconnecting reactor 6u is provided between the U-phase AC system 7u and the midpoint of the U-phase reactor 5u. The V-phase interconnecting reactor 6v is provided between the V-phase AC system 7v and the midpoint of the V-phase reactor 5v. The W-phase interconnecting reactor 6w is provided between the W-phase AC system 7w and the midpoint of the W-phase reactor 5w. A three-phase interconnection transformer may be provided instead of the three-phase interconnection reactors 6u, 6v, 6w.

  Next, a configuration in which the control device 3 transmits a gate signal to each of the cells CL11 to CL68 will be described.

  The arms 4up to 4wm are connected by transmission lines L11 to L62 for each of the two sets of cells CL11 to CL68 divided into four. Here, the number of cells CL11 to CL68 divided by each arm 4up to 4wm is made the same as the minimum number that can output a normal voltage. Accordingly, here, the minimum number is four.

  FIG. 3 is a structural diagram simply showing the structure of the data DT transmitted to each of the cells CL11 to CL68 by serial communication according to the present embodiment. The data DT stores four data DT1, DT2, DT3, and DT4 corresponding to the four cells CL11 to CL68 performing serial communication.

  The control device 3 transmits data DT for serial communication for each of the transmission lines L11 to L62. Each of the cells CL11 to CL68 takes out data DT1 to DT4 corresponding to itself from the data DT received from the transmission lines L11 to L62. The data DT1 to DT4 extracted by the cells CL11 to CL68 include a gate signal. Each of the cells CL11 to CL68 is driven by its extracted gate signal.

  Next, the operation continuity with respect to the line abnormality of the self-excited power conversion device 1 will be described. Here, the line includes hardware (for example, transmission lines L11 to L62 or cells CL11 to CL68) necessary for serial communication and all software.

  Each arm 4up to 4wm is connected to the control device 3 by two transmission lines L11 to L62. The control device 3 is connected to four cells per line. Therefore, each arm 4up-4wm can drive the four cells CL11-CL68 necessary for outputting a normal voltage if one line is normal.

  According to the present embodiment, the cells CL11 to CL68 constituting each arm 4up to 4wm are divided by the minimum number of units necessary for continuous operation, and serial communication is performed for each of the divided cells CL11 to CL68, so that all If at least one of the two lines is normal in the arms 4up to 4wm, the self-excited power conversion device 1 can continue operation.

(Second Embodiment)
FIG. 4 is a configuration diagram showing a configuration of a self-excited power conversion device 1A according to the second embodiment of the present invention.

  The self-excited power conversion device 1A is the same as the self-excited power conversion device 1 according to the first embodiment shown in FIG. 1 except that the configuration of the line connecting the control device 3 and the cells CL11 to CL68 is different. This is the same as the embodiment.

  The control device 3 performs serial communication with the cells CL11 to CL68 constituting the arms 4up to 4wm via the transmission lines L1, L2, L3 and L4. The transmission lines L1 to L4 are configured by optical fiber cables and repeaters.

  The transmission line L1 daisy chain connects the first and second cells CL11, CL12, CL21, CL22, CL31, CL32, CL41, CL42, CL51, CL52, CL61, CL62 from the positive side of each arm 4up to 4wm.

  The transmission line L2 daisy-chains the third and fourth cells CL13, CL14, CL23, CL24, CL33, CL34, CL43, CL44, CL53, CL54, CL63, and CL64 from the positive side of each arm 4up to 4wm.

  The transmission line L3 daisy chain connects the fifth and sixth cells CL15, CL16, CL25, CL26, CL35, CL36, CL45, CL46, CL55, CL56, CL65, and CL66 from the positive side of each arm 4up to 4wm.

  The transmission line L4 daisy chain connects the seventh and eighth cells CL17, CL18, CL27, CL28, CL37, CL38, CL47, CL48, CL57, CL58, CL67, and CL68 from the positive side of each arm 4up to 4wm.

  Next, the continuity of operation for the line abnormality of the self-excited power conversion device 1A will be described. Here, as in the first embodiment, each arm 4up to 4wm can output a normal voltage if at least four cells CL11 to CL68 operate normally.

  The control device 3 is connected to each of the arms 4up to 4wm via four transmission lines L1 to L4. The control device 3 is connected to two cells of arms 4up to 4wm all around one line. Therefore, if the two lines are normal, the control device 3 can drive the four cells CL11 to CL68 necessary for outputting normal voltages from all the arms 4up to 4wm.

  According to this embodiment, each transmission line L1 to L4 is connected so as to perform serial communication between the two cells CL11 to CL68 of all the arms 4up to 4wm and the control device 3, so that four lines can be obtained. If at least two lines of transmission lines L1 to L4 are normal, self-excited power conversion device 1A can continue operation.

  Thus, by connecting all the transmission lines L1 to L4 so as to perform serial communication between the cells CL11 to CL68 and the control device 3 across all the arms 4up to 4wm, the number of lines can be reduced. With the transmission lines L1 to L4, the operation continuity with respect to the line abnormality of the self-excited power conversion device 1A can be efficiently increased.

  The configuration of the cell CL is not limited to that shown in FIG. Any circuit may be used as long as it is a converter including a switching element and functions as a configuration of a self-excited power converter. For example, the cell CL may be a bidirectional chopper or a full bridge converter.

  Moreover, in each embodiment, each arm 4up-4wm is not restricted to what was comprised by the eight cells CL11-CL68, and may be comprised by how many cells. For example, each arm 4up to 4wm may include cells that are not used during one cycle of the output voltage even during normal operation in order to ensure the redundancy of the configuration. Further, the self-excited power conversion devices 1 and 1A are not limited to those configured by the six arms 4up to 4wm, and may be configured by any number of arms. For example, the self-excited power conversion device 1 or 1A has been described as a configuration that converts DC power to three-phase AC power, but a configuration that converts DC power to single-phase AC power may be used. In this case, a self-excited power converter that converts DC power into single-phase AC power with four arms can be configured.

  Furthermore, in each embodiment, when the cells CL11 to CL68 are daisy chain connected, they may be connected in any order. As long as it connects so that all the arms 4up-4wm may be straddled, it may connect with the cells CL11-CL68 located in each arm 4up-4wm.

  In the second embodiment, the four transmission lines L1 to L4 have been described. However, any number of transmission lines L1 to L4 may be used as long as the transmission lines L1 to L4 have two or more lines. Moreover, although it comprised so that two cells CL11-CL68 of each arm 4up-4wm may be connected by one transmission line L1-L4, it is not restricted to this. Each transmission line L1 to L4 may be configured to connect one cell CL11 to CL68 with each arm 4up to 4wm, or to connect three or more cells CL11 to CL68 with each arm 4up to 4wm. You may comprise. Further, each transmission line L1 to L4 is configured to connect the same number of cells CL11 to CL68 with each arm 4up to 4wm, so that when any one of the transmission lines L1 to L4 becomes line abnormal, Since the number of cells CL11 to CL68 that cannot be driven by the arms 4up to 4wm is the same, it is possible to easily control to balance the voltages output from the arms 4up to 4wm.

  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 ... Self-excited power converter device, 2 ... DC power supply, 3 ... Control device, 4up, 4um, 4vp, 4vm, 4wp, 4wm ... Arm, 5u, 5v, 5w ... Reactor, 6u, 6v, 6w ... Interconnection reactor, 7u, 7v, 7w... AC system, CL11 to CL68... Cell, L11 to L62.

Claims (2)

A plurality of arms comprising a plurality of unit converters connected in series with each of the positive and negative electrodes of each phase of the power conversion circuit for converting DC power into three-phase AC power;
Dividing the plurality of unit converters constituting each arm by a minimum number necessary for continuous operation, and a plurality of transmission lines connected for serial communication of the unit converters for each necessary minimum number A self-excited power conversion device comprising: Consists of a plurality of arms composed of a plurality of unit converters in which the positive and negative electrodes of each phase of a power conversion circuit that converts DC power into three-phase AC power are connected in series, and the unit converter is serially communicated A self-excited power conversion device manufacturing method for connecting with a plurality of transmission lines,
Dividing the plurality of unit converters constituting each arm by the minimum number necessary for continued operation,
A method of manufacturing a self-excited power converter, comprising connecting the unit converters by the transmission path for each of the minimum necessary numbers.

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