JP2019213382A - Power conversion apparatus - Google Patents

Abstract

To provide a power conversion apparatus of a multistep constitution capable of simplifying the configuration of a host controller, even when operation continuity is improved by enabling bypass of a failed converter.SOLUTION: A power conversion apparatus comprises a main circuit part having multiple converters, a host controller for controlling operation of each converter. Each converter has multiple switching elements, multiple rectifier elements, a charge storage element connected in parallel with the multiple switching elements, a control section for controlling the multiple switching elements, a power supply circuit for supplying control power supply to the control section, and a voltage detector for detecting the voltage of the charge storage element. The host controller calculates the average value of voltage of the charge storage elements, the control section determines an abnormality of voltage of the charge storage element on the basis of the detection results from the voltage detector and the average value, and when the abnormality is determined, the converter determined to be abnormal is brought into bypass state.SELECTED DRAWING: Figure 1

Description

  Embodiments described herein relate generally to a power conversion apparatus.

  There is a multi-stage power converter that includes a plurality of converters connected in series and a host controller that controls the operation of each converter. Each converter controls a plurality of switching elements, a rectifying element connected in parallel to each switching element, a charge storage element connected in parallel to each switching element, and on / off of each switching element And a control unit.

  When the number of each converter is large in series, the potential of the host control device is lower than the potential of each converter. In such a case, it is difficult to supply control power from the host controller to the control unit of each converter from the viewpoint of insulation. For this reason, each converter is provided with a power supply circuit that supplies control power to the control unit from the main circuit side such as a charge storage element.

  Further, in a power converter having a multi-stage configuration, a failure of each converter is monitored by a host controller, and when a failure is detected, the converter is put into a bypass state. Thereby, even when a failure occurs in any of the plurality of converters connected in series, the operation can be continued, and the operation continuity of the power conversion device can be improved.

  However, if the control relating to the failure of a plurality of converters is performed only by the host controller, the configuration of the host controller becomes complicated. For example, the size of the host control device is increased and the cost is increased.

  For this reason, in a power converter having a multi-stage configuration, it is desired to simplify the configuration of the host control device even when the failed converter can be bypassed to improve the operation continuity.

JP2013-27260A

  The embodiment of the present invention provides a multi-stage power conversion device that can simplify the configuration of the host control device even when the continuity of operation is improved by enabling bypass of a failed converter.

  According to an embodiment of the present invention, a plurality of converters connected in series are provided, and conversion of AC power to DC power and conversion of DC power to AC power are performed by the operations of the plurality of converters. A main circuit unit that performs at least one of the above and a host controller that controls the operation of the plurality of converters, each of the plurality of converters being a plurality of half-bridge or full-bridge connected A switching element; a plurality of rectifying elements connected in parallel to each of the plurality of switching elements; a charge storage element connected in parallel to the plurality of switching elements; and turning on / off the plurality of switching elements A power supply circuit that generates a control power source for the control unit and supplies the generated control power source to the control unit based on the charge accumulated in the charge storage element, A voltage detector that detects a voltage of the charge storage element and outputs a detection result to the control unit and the host controller, and the host controller includes the voltage of each of the plurality of converters. Based on the detection result of the detector, calculate an average value of the voltage of the charge storage element of the plurality of converters, and output the average value to the control unit of each of the plurality of converters, The controller determines an abnormality in the voltage of the charge storage element based on the detection result of the voltage detector and the average value, and bypasses the converter determined to be abnormal when the abnormality is determined. A power conversion device to be in a state is provided.

  A multi-stage power conversion device that can simplify the configuration of the host control device even when the operation continuity is improved by enabling bypass of the failed converter is provided.

It is a block diagram showing typically the power converter concerning a 1st embodiment. It is a block diagram showing typically the converter concerning a 1st embodiment. It is a block diagram showing typically the module concerning a 1st embodiment. It is a flowchart which represents typically an example of operation | movement of the power converter device which concerns on 1st Embodiment. It is a block diagram showing typically a module concerning a 2nd embodiment. It is a flowchart which represents typically an example of operation | movement of the power converter device which concerns on 2nd Embodiment. It is a block diagram showing typically the modification of the module concerning a 2nd embodiment. It is a block diagram showing typically the modification of a main circuit.

Each embodiment will be described below with reference to the drawings.
The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between the parts, and the like are not necessarily the same as actual ones. Further, even when the same part is represented, the dimensions and ratios may be represented differently depending on the drawings.
Note that, in the present specification and each drawing, the same elements as those described above with reference to the previous drawings are denoted by the same reference numerals, and detailed description thereof is omitted as appropriate.

(First embodiment)
FIG. 1 is a block diagram schematically illustrating the power conversion apparatus according to the first embodiment.
As shown in FIG. 1, the power conversion device 10 includes a main circuit unit 12 and a host control device 14. The power converter 10 is used for a DC power transmission system, for example. The power converter 10 is connected to the AC power system 2 and the pair of DC power transmission lines 3 and 4 in the DC power transmission system.

  The DC power transmission system includes, for example, a transformer 6. The main circuit unit 12 of the power conversion device 10 is connected to the AC power system 2 via the transformer 6. The AC power of the AC power system 2 is three-phase AC power. More specifically, it is symmetrical three-phase AC power. The transformer 6 converts the three-phase AC power of the AC power system 2 into AC power corresponding to the main circuit unit 12. The transformer 6 changes the effective value of each phase of the three-phase AC power in accordance with the main circuit unit 12. The transformer 6 is a three-phase transformer. The transformer 6 is provided as necessary and can be omitted. The main circuit unit 12 may be directly supplied with the three-phase AC power of the AC power system 2.

  The power converter 10 converts the three-phase AC power supplied from the AC power system 2 into DC power, and supplies the converted DC power to the DC power transmission lines 3 and 4. Further, the power conversion device 10 converts the DC power supplied from the DC power transmission lines 3 and 4 into three-phase AC power, and supplies the converted three-phase AC power to the AC power system 2. As described above, the power conversion apparatus 10 performs AC / DC conversion from AC to DC and AC / DC conversion from DC to AC.

  For example, the DC transmission line 3 is a transmission line on the high voltage side of DC power, and the DC transmission line 4 is a transmission line on the low voltage side of DC power. The power conversion device 10 outputs the converted DC power to the DC transmission lines 3 and 4 so that the DC transmission line 3 side is at a high voltage and the DC transmission line 4 side is at a low voltage.

  The main circuit unit 12 is provided between the AC power system 2 and the DC power transmission lines 3 and 4. The main circuit unit 12 performs conversion from three-phase AC power to DC power and conversion from DC power to three-phase AC power. The main circuit unit 12 is, for example, an MMC (Modular Multilevel Converter) type power converter. The MMC type main circuit section 12 has a plurality of converters connected in series. Each converter includes a plurality of switching elements that are half-bridge connected or full-bridge connected, and a charge storage element that is connected in parallel to each switching element. The main circuit unit 12 performs AC / DC conversion by switching of each switching element.

  The host control device 14 is connected to the main circuit unit 12. The host controller 14 controls on / off of each switching element to control the conversion from the three-phase AC power to the DC power and the conversion from the DC power to the three-phase AC power by the main circuit unit 12. .

  The main circuit section 12 includes a first and second pair of DC terminals 20a and 20b, first to third AC terminals 21a to 21c, and first to sixth arm sections 22a to 22f. Have.

  The first DC terminal 20a is connected to the DC transmission line 3 on the high voltage side. The second DC terminal 20b is connected to the DC transmission line 4 on the low voltage side. Thus, the DC power converted by the main circuit unit 12 is supplied to the DC power transmission lines 3 and 4, and the DC power supplied from the DC power transmission lines 3 and 4 is input to the main circuit unit 12.

  The first arm portion 22a is connected to the first DC terminal 20a. The second arm portion 22b is connected between the first arm portion 22a and the second DC terminal 20b. The first arm portion 22a and the second arm portion 22b are connected in series between the DC terminals 20a and 20b.

  The third arm portion 22c is connected to the first DC terminal 20a. The fourth arm portion 22d is connected between the third arm portion 22c and the second DC terminal 20b. The third arm part 22c and the fourth arm part 22d are connected in parallel to the first arm part 22a and the second arm part 22b.

  The fifth arm portion 22e is connected to the first DC terminal 20a. The sixth arm portion 22f is connected between the fifth arm portion 22e and the second DC terminal 20b. That is, the fifth arm portion 22e and the sixth arm portion 22f are connected in parallel to the first arm portion 22a and the second arm portion 22b, and to the third arm portion 22c and the fourth arm portion 22d. Connected in parallel.

  In the main circuit unit 12, the first leg LG1 is configured by the first arm unit 22a and the second arm unit 22b, the second leg LG2 is configured by the third arm unit 22c and the fourth arm unit 22d, and the fifth arm unit. The third leg LG3 is configured by the 22e and the sixth arm portion 22f. That is, in this example, the main circuit unit 12 is a three-leg, six-arm three-phase inverter. The first arm portion 22a, the third arm portion 22c, and the fifth arm portion 22e are upper arms. The second arm part 22b, the fourth arm part 22d, and the sixth arm part 22f are lower arms.

The first arm portion 22a has a plurality of converters UP1, UP2,... UPM ₁ connected in series. The second arm portion 22b has a transducer UN1, UN2 ... UNM ₂ of multiple connected in series. The third arm portion 22c has a plurality of converters VP1, VP2,... VPM ₃ connected in series. The fourth arm portion 22d has a plurality of converters VN1, VN2,... VNM ₄ connected in series. The fifth arm portion 22e has a plurality of converters WP1, WP2,... WPM ₅ connected in series. The sixth arm portion 22f includes a plurality of converters WN1, WN2,... WNM ₆ connected in series.

However, in the following, each transducer _{UP1, UP2 ... UPM 1, UN1} , UN2 ... UNM 2, VP1, VP2 ... VPM 3, VN1, VN2 ... VNM 4, WP1, WP2 ... WPM 5, WN1, WN2 ... WNM 6 When collectively referred to, it is referred to as “converter CELL”.

In each of the arm portions _{22a~22f, M 1, M 2,} M 3, M 4, M 5, M 6 represents the number of series-connected transducers CELL. In each arm part 22a-22f, the number of the converters CELL connected in series is about 100 to 120, for example. However, the number of converters CELL connected in series is not limited to this and may be any number.

  The number of converters CELL provided in each of the arm portions 22a to 22f is substantially the same. For example, when a large number of converters CELL are connected, the number of converters CELL provided in each of the arm units 22a to 22f may be different within a range that does not affect the operation of the main circuit unit 12. For example, when 100 converters CELL are connected in series to one arm part, the number of converters CELL provided in another arm part may differ by one or two.

  Each of the arm portions 22a to 22f further includes a buffer reactor 23a to 23f and a plurality of current detectors 24a to 24f. The power conversion device 10 further includes a voltage detection unit 25.

  Each buffer reactor 23a-23f is connected in series with each converter CELL in each arm part 22a-22f. The buffer reactor 23a of the first arm portion 22a is provided between a connection point between the AC terminal 21a and the first arm portion 22a and the second arm portion 22b and the converter UP1. The buffer reactor 23b of the second arm portion 22b is provided between a connection point between the AC terminal 21a, the first arm portion 22a and the second arm portion 22b, and the converter UN1. The buffer reactor 23c of the third arm portion 22c is provided between a connection point between the AC terminal 21b, the third arm portion 22c and the fourth arm portion 22d, and the converter VP1. The buffer reactor 23d of the fourth arm portion 22d is provided between a connection point between the AC terminal 21b, the third arm portion 22c and the fourth arm portion 22d, and the converter VN1. The buffer reactor 23e of the fifth arm portion 22e is provided between the connection point between the AC terminal 21c and the fifth arm portion 22e and the sixth arm portion 22f and the converter WP1. The buffer reactor 23f of the sixth arm portion 22f is provided between the connection point between the AC terminal 21c, the fifth arm portion 22e, and the sixth arm portion 22f and the converter WN1.

  The current detector 24a is provided in the first arm part 22a and detects a current flowing through the first arm part 22a. That is, the current detector 24a detects the arm current of the first arm portion 22a. The current detector 24a is connected to the host controller 14 via a wiring or the like not shown. The current detector 24 a inputs the detected current value of the first arm portion 22 a to the host controller 14. As a result, the current value of the first arm portion 22a is input to the host control device 14.

  Similarly, the current detector 24b detects the current flowing through the second arm portion 22b, and inputs the detected current value to the host controller 14. The current detector 24 c detects the current flowing through the third arm portion 22 c and inputs the detected current value to the host controller 14. The current detector 24 d detects the current flowing through the fourth arm portion 22 d and inputs the detected current value to the host controller 14. The current detector 24 e detects the current flowing through the fifth arm portion 22 e and inputs the detected current value to the host control device 14. The current detector 24 f detects the current flowing through the sixth arm portion 22 f and inputs the detected current value to the host controller 14.

  The voltage detection unit 25 detects the AC voltage (phase voltage) of each phase of the AC power system 2 and inputs the detected value to the host controller 14. The voltage detection unit 25 may be connected to the primary side of the transformer 6 or may be connected to the secondary side.

  In the main circuit part 12, the connection point between the first arm part 22a and the second arm part 22b, the connection point between the third arm part 22c and the fourth arm part 22d, and the fifth arm part 22e and the sixth arm part. Each of the connection points with 22f becomes an AC output point.

  The first AC terminal 21a is connected to a connection point between the first arm portion 22a and the second arm portion 22b. The second AC terminal 21b is connected to a connection point between the third arm portion 22c and the fourth arm portion 22d. The third AC terminal 21c is connected to a connection point between the fifth arm portion 22e and the sixth arm portion 22f. Each AC terminal 21a-21c is connected to the transformer 6, for example.

  Each converter CELL is connected to the host controller 14 via a signal line 26. The host controller 14 controls the operation of the converter CELL by inputting a control signal to the converter CELL via the signal line 26. In addition, the converter CELL inputs, for example, a control signal and a protection signal related to the control and operation protection of the converter CELL to the upper control device 14 via another signal line (not shown).

  The communication method between the host controller 14 and each converter CELL is not limited to the above. For example, the host controller 14 and each converter CELL may be daisy chain connected. The communication method between the host controller 14 and each converter CELL may be any communication method capable of transmitting and receiving signals between the host controller 14 and each converter CELL.

FIG. 2 is a block diagram schematically illustrating the converter according to the first embodiment.
As illustrated in FIG. 2, the converter CELL includes a main circuit 40, a charge storage element 45, a control unit 46, a power feeding circuit 48, and a voltage detector 50.

  The main circuit 40 includes a first connection terminal 40a, a second connection terminal 40b, a first switching element 41, and a second switching element 42. Each of the switching elements 41 and 42 includes a pair of main terminals and a control terminal. The control terminal controls a current flowing between the pair of main terminals. For each switching element 41, 42, for example, a self-extinguishing element such as an IGBT is used. The pair of main terminals is, for example, an emitter and a collector, and the control terminal is, for example, a gate. For each switching element 41, 42, for example, a normally-off type semiconductor element is used.

  The pair of main terminals of the second switching element 42 are connected in series to the pair of main terminals of the first switching element 41. The first connection terminal 40 a is connected between the first switching element 41 and the second switching element 42. The second connection terminal 40 b is connected to the main terminal on the opposite side of the main terminal connected to the second switching element 42 of the first switching element 41.

  The charge storage element 45 is connected in parallel to the first switching element 41 and the second switching element 42. The charge storage element 45 is a capacitor, for example. Supply of power to the converter CELL is performed via the connection terminals 40a and 40b. In other words, the charge storage element 45 is charged by the electric power supplied via the connection terminals 40a and 40b.

  The first switching element 41 is connected to a rectifying element 41d in antiparallel with the pair of main terminals. The forward direction of the rectifying element 41 d is opposite to the direction of the current flowing between the pair of main terminals of the first switching element 41. Similarly, the rectifying element 42d is connected to the second switching element 42 in antiparallel with the pair of main terminals. The rectifying elements 41d and 42d are so-called reflux diodes.

  In this example, in the main circuit 40, the switching elements 41 and 42 are half-bridge connected. In other words, the main circuit 40 is a chopper circuit. The first switching element 41 is a so-called low-side switch, and the second switching element 42 is a so-called high-side switch.

  The control unit 46 controls on / off of the switching elements 41 and 42. The control unit 46 is connected to the control terminal of the first switching element 41 through the gate circuit 51. The control unit 46 is connected to the control terminal of the second switching element 42 via the gate circuit 52. Moreover, the control part 46 is connected with the high-order control apparatus 14 via the signal wire | line 26, for example.

  The host controller 14 transmits a control signal for controlling on / off of each switching element 41, 42 to the controller 46 via the signal line 26. The control unit 46 inputs a drive signal for switching on / off of each switching element 41, 42 to the gate circuits 51, 52 based on the input control signal.

  The gate circuit 51 is connected to the control terminal of the first switching element 41. The gate circuit 52 is connected to the control terminal of the second switching element 42. The gate circuits 51 and 52 switch the switching elements 41 and 42 on and off based on the drive signal input from the control unit 46. Thereby, on / off of each switching element 41 and 42 is controlled according to the control signal from the host controller 14. The host controller 14 generates a control signal for each converter CELL, and controls on / off of each switching element 41, 42 of each converter CELL. Thereby, the host controller 14 controls the power conversion by the main circuit unit 12.

  Note that the configuration of the converter CELL is not limited to the above, and may be any configuration that can control the on / off of the switching elements 41 and 42. For example, the gate circuits 51 and 52 are provided as necessary and can be omitted.

  The power feeding circuit 48 is connected in parallel to the charge storage element 45. The power feeding circuit 48 generates a control power source for the control unit 46 based on the charges accumulated in the charge storage element 45 and supplies the generated control power source to the control unit 46. In this example, the power supply circuit 48 also supplies control power to the gate circuits 51 and 52. For example, the power supply circuit 48 generates control power corresponding to each of the control unit 46 and the gate circuits 51 and 52, and supplies corresponding control power to each of the control unit 46 and the gate circuits 51 and 52. The control unit 46 operates in response to the supply of control power from the power supply circuit 48.

  The voltage detector 50 is electrically connected to the charge storage element 45. In addition, the voltage detector 50 is connected to the control unit 46 and is connected to the host control device 14 via, for example, the control unit 46 and the signal line 26. The voltage detector 50 detects the voltage of the charge storage element 45 and outputs the detection result to the control unit 46 and the host control device 14. The configuration of the voltage detector 50 may be any configuration that can output the detection result to the control unit 46 and the host controller 14.

  The plurality of converters CELL are modularized for each of at least two converters CELL. In this example, one module MDL is formed by two converters CELL. Therefore, the main circuit unit 12 has a plurality of modules MDL. In the two converters CELL of the module MDL, power sources are multiplexed. The power supply circuit 48 supplies control power to the control unit 46 and the gate circuits 51 and 52 of each converter CELL included in the module MDL. As a result, even when one of the power supply circuits 48 of each converter CELL in the module MDL fails, the control power is supplied from the power supply circuit 48 of the other converter CELL to the control unit 46 and the gate circuits 51 and 52. be able to. Therefore, even when one power feeding circuit 48 fails, the operation of the power conversion device 10 can be continued, and the continuity of operation of the power conversion device 10 can be improved.

  Hereinafter, one converter CELL included in the module MDL is referred to as “first converter CELL1”, and the other converter CELL is referred to as “second converter CELL2”. The power supply circuit 48 of the first converter CELL1 supplies control power to the control unit 46 and the gate circuits 51 and 52 of the first converter CELL1, and to the control unit 46 and the gate circuits 51 and 52 of the second converter CELL2. Also supply control power. Similarly, the power supply circuit 48 of the second converter CELL2 supplies control power to the control unit 46 and the gate circuits 51 and 52 of the second converter CELL2, and the control unit 46 and the gate circuit 51 of the first converter CELL1. , 52 is also supplied with control power.

  The number of converters CELL included in the module MDL is not limited to two and may be three or more. Moreover, each converter CELL does not necessarily need to be modularized.

FIG. 3 is a block diagram schematically illustrating the module MDL according to the first embodiment.
As shown in FIG. 3, the control unit 46 of each converter CELL outputs the voltage of the charge storage element 45 detected by the voltage detector 50 (hereinafter referred to as a cell voltage) to the host controller 14. The host controller 14 receives the cell voltage of each converter CELL. The cell voltage input to the host control device 14 may be input directly from the voltage detector 50 to the host control device 14 without going through the control unit 46.

  The host controller 14 calculates the average value of the cell voltages of the converters CELL based on the input cell voltages of the converters CELL. And the high-order control apparatus 14 outputs the calculated average value to each control part 46 of each converter CELL.

  The control unit 46 of each converter CELL has a determination circuit 54. The determination circuit 54 determines an abnormality in the cell voltage of the charge storage element 45 based on the detection result of the voltage detector 50 and the input average value. For example, when the difference between the detection result of the voltage detector 50 and the average value is less than a predetermined value, the determination circuit 54 determines that the cell voltage is normal, and the difference between the detection result of the voltage detector 50 and the average value is If it is equal to or greater than a predetermined value, the cell voltage is determined to be abnormal.

  When the determination circuit 54 determines that the determination circuit 54 is normal, the control unit 46 controls on / off of the switching elements 41 and 42 according to the control signal from the host control device 14. On the other hand, when the determination circuit 54 determines abnormality, the control unit 46 places the connection terminals 40a and 40b of the converter CELL determined as abnormal in a bypass state.

  Here, the “bypass state” is a state in which the first connection terminal 40a and the second connection terminal 40b are electrically connected (short-circuited). In this example, for example, the first switching element 41 is turned on and the second switching element 42 is turned off, so that the bypass state can be obtained. Thereby, in each converter CELL connected in series, even when any converter CELL fails, operation of the power converter 10 is continued by setting the failed converter CELL in a bypass state. be able to. The bypass state may be, for example, a state in which the first connection terminal 40a and the second connection terminal 40b are electrically connected using a switch or the like different from the switching elements 41 and 42.

  When the determination circuit 54 determines abnormality and the connection terminals 40a and 40b of the converter CELL determined to be abnormal are put in a bypass state, the control unit 46 displays information indicating the failure of the converter CELL. Output to. For example, based on information from the control unit 46, the host controller 14 accumulates the number of failed converters CELL for each of the arm units 22a to 22f, and the number of failed converters CELL has reached a predetermined number. In this case, power conversion by the main circuit unit 12 is stopped.

  The converters CELL included in the module MDL are connected to each other. The first converter CELL1 is connected to the second converter CELL2. For example, when each converter CELL and the host controller 14 are individually connected by a signal line 26 or the like, the first converter CELL1 and the second converter CELL2 are connected via a dedicated signal line or the like. Connected to each other. For example, when each converter CELL and the host controller 14 are connected in a daisy chain, the first converter CELL1 and the second converter CELL2 are connected to each other via a daisy chain signal line.

  Each converter CELL included in the module MDL shares the detection result of the voltage detector 50 with each other. The detection result of the voltage detector 50 of the first converter CELL1 is input to the control unit 46 of the first converter CELL1, and is also input to the control unit 46 of the second converter CELL2. Similarly, the detection result of the voltage detector 50 of the second converter CELL2 is input to the control unit 46 of the second converter CELL2 and also input to the control unit 46 of the first converter CELL1.

  The control unit 46 determines an abnormality in the voltage of each charge storage element 45 of each of the modularized converters CELL. Then, the control unit 46 can put the converter CELL determined to be abnormal into a bypass state.

  For example, when the control unit 46 of the second converter CELL2 determines that the cell voltage of the first converter CELL1 is abnormal, the controller 46 outputs a bypass signal to the gate circuits 51 and 52 of the first converter CELL1. The gate circuits 51 and 52 of the first converter CELL1 place the connection terminals 40a and 40b in a bypass state according to the input of the bypass signal.

  Thereby, for example, even when one of the control units 46 of each converter CELL included in the module MDL fails, the operation can be continued by bypassing the connection terminals 40a and 40b. Therefore, the operation continuity of the power converter 10 can be further improved.

  For example, when only the determination circuit 54 of the control unit 46 of the first converter CELL1 fails and an abnormality cannot be properly determined, the error is input from the control unit 46 of the second converter CELL2. In response to the bypass signal, the control unit 46 of the first converter CELL1 may drive the gate circuits 51 and 52 to place the connection terminals 40a and 40b in a bypass state.

  As described above, the configuration in which the control unit 46 of the second converter CELL2 can put the first converter CELL1 in the bypass state is that the control unit 46 of the second converter CELL2 has each of the first converter CELL1. The configuration may be such that the connection terminals 40a and 40b are directly controlled to be in a bypass state, or the control unit 46 of the first converter CELL1 is connected to each connection in accordance with an instruction from the control unit 46 of the second converter CELL2. The terminal 40a and 40b may be configured to be in a bypass state.

  For example, when the determination circuit 54 does not determine that there is an abnormality and the bypass is instructed from the control unit 46 of another converter CELL included in the module MDL, the control unit 46 gives priority to the bypass. Thereby, driving continuity and safety can be further improved.

FIG. 4 is a flowchart schematically illustrating an example of the operation of the power conversion device according to the first embodiment.
FIG. 4 schematically illustrates an example of an operation related to the bypass control of the control unit 46. Hereinafter, the control unit 46 of the first converter CELL1 will be described as an example. Since the operation of the control unit 46 of the second converter CELL2 is substantially the same as the operation of the control unit 46 of the first converter CELL1, detailed description thereof is omitted.

  At the start of the operation of the power converter 10, the charge storage element 45 of each converter CELL is charged by, for example, an initial charging circuit (not shown). When the charge storage element 45 is charged, the power feeding circuit 48 starts to operate. The power supply circuit 48 that has started operating supplies control power corresponding to each of the control unit 46 and the gate circuits 51 and 52. Thereby, the control unit 46 is activated in response to the supply of the control power from the power supply circuit 48 (step S11 in FIG. 4).

  The detection result of the voltage detector 50 of the first converter CELL1 and the detection result of the voltage detector 50 of the second converter CELL2 are input to the control unit 46 of the first converter CELL1. The control unit 46 of the first converter CELL1 outputs the input cell voltages of the first converter CELL1 and the second converter CELL to the host controller 14 (step S12 in FIG. 4). The output of the cell voltage from the control unit 46 to the host control device 14 may be performed periodically at predetermined intervals or may be performed continuously.

  When the host controller 14 receives cell voltage information from each converter CELL, the host controller 14 calculates an average value of the cell voltages of the input converters CELL (step S13 in FIG. 4). Note that the average value of the cell voltages may be calculated for all the converters CELL, or may be calculated individually for each arbitrary number of converters CELL. For example, the average value of the cell voltage of each converter CELL may be calculated for each arm unit 22a to 22f. Thereafter, the host controller 14 outputs the calculated average value to the control unit 46 of each converter CELL (step S14 in FIG. 4).

  When the average value is input from the host controller 14, the control unit 46 causes the determination circuit 54 to determine whether the cell voltage is abnormal (step S15 in FIG. 4).

  When it is determined that the cell voltage is normal, the control unit 46 returns to the process of step S12 and repeats the same process. On the other hand, when the cell voltage is determined to be abnormal, the control unit 46 places the connection terminals 40a and 40b of the converter CELL determined to be abnormal in a bypass state (step S16 in FIG. 4).

  As described above, in the power conversion device 10 according to the present embodiment, each converter CELL determines whether the cell voltage is abnormal. Thereby, the configuration of the host control device 14 can be simplified as compared with the case where all the determinations of the abnormality of the cell voltage of each converter CELL are performed by the host control device 14. In the power converter 10 according to the present embodiment, the configuration of the host controller 14 can be simplified even when the failed converter CELL can be bypassed to improve the operation continuity. For example, an increase in size and cost of the host control device 14 can be suppressed.

  Further, the control unit 46 of the first converter CELL1 also determines abnormality of the cell voltage of the second converter CELL2. When the control unit 46 of the first converter CELL1 determines that the cell voltage of the second converter CELL2 is abnormal, the controller 46 makes the second converter CELL2 in a bypass state. Thereby, driving continuity can be further improved.

(Second Embodiment)
FIG. 5 is a block diagram schematically illustrating the module MDL according to the second embodiment.
Note that components that are substantially the same in function and configuration as those in the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.
As illustrated in FIG. 5, each converter CELL further includes a storage unit 60. The storage unit 60 stores failure information 62 that represents the state of the failure of the converter CELL.

  The failure information 62 includes, for example, a determination result of cell voltage abnormality determined by the determination circuit 54. Thereby, the control unit 46 can recognize whether the cell voltage is determined to be normal or abnormal by referring to the failure information 62.

  The information included in the failure information 62 is not limited to the information on the determination result of the cell voltage abnormality. For example, information on abnormality of the switching elements 41 and 42 may be included in the failure information 62. The information included in the failure information 62 may be any information related to the failure of the converter CELL.

  Further, the converters CELL included in the module MDL share the failure information 62 with each other. The failure information 62 includes, for example, information indicating a failure state of each converter CELL included in the module MDL. For example, the failure information 62 of the first converter CELL1 includes the determination result of the cell voltage of the first converter CELL1, and also includes the determination result of the cell voltage of the second converter CELL2. The failure information 62 of the second converter CELL2 includes the determination result of the cell voltage of the second converter CELL2, and also includes the determination result of the cell voltage of the first converter CELL1. Thereby, by referring to the failure information 62, it is possible to recognize each failure state of each converter CELL included in the module MDL. Note that the storage unit 60 may store, for example, a plurality of pieces of failure information 62 for each converter CELL included in the module MDL.

FIG. 6 is a flowchart schematically illustrating an example of the operation of the power conversion device according to the second embodiment.
FIG. 6 schematically illustrates an example of the operation of the control unit 46 when starting up.
As described above, the control unit 46 is activated in response to the supply of control power from the power supply circuit 48 (step S21 in FIG. 6). After starting, the control unit 46 refers to the failure information 62 in the storage unit 60 (step S22 in FIG. 6).

  The control unit 46 refers to the failure information 62 and confirms whether or not the converter CELL in its own module MDL is stored as a failure in the failure information 62 (step S23 in FIG. 6).

  If it is stored that the controller 46 is malfunctioning, the controller 46 causes the converter CELL in the module MDL to bypass the converter CELL stored as malfunction (step S24 in FIG. 6).

  On the other hand, when it is stored that there is no failure, the control unit 46 controls the on / off of the switching elements 41 and 42 in accordance with the control signal from the host control device 14 and performs power conversion. Start control.

  Thus, in this embodiment, each converter CELL stores the failure information 62. Thereby, for example, the configuration of the host control device 14 can be simplified as compared with the case where the host control device 14 stores the failure information 62 of each converter CELL.

  Further, the control unit 46 refers to the failure information 62 to confirm each failure of each converter CELL included in the module MDL, and puts the converter CELL stored as a failure into a bypass state. The control unit 46 of the first converter CELL1 also confirms the failure of the second converter CELL2. When it is stored that the second converter CELL2 has failed, the control unit 46 of the first converter CELL1 puts the second converter CELL2 into a bypass state.

  Thereby, for example, even when any of the control units 46 and storage units 60 of each converter CELL included in the module MDL is out of order, the operation can be continued, and the operation continuity is further improved. be able to.

  For example, the control unit 46 gives priority to the bypass when it is instructed by the control unit 46 of another converter CELL included in the module MDL in a state where the converter CELL is not determined to be abnormal. Thereby, driving continuity and safety can be further improved.

FIG. 7 is a block diagram schematically illustrating a modification example of the module MDL according to the second embodiment.
As shown in FIG. 7, the determination circuit 54 is omitted in this example. In this example, for example, the host controller 14 performs all the determinations of abnormal cell voltages of the converters CELL. As described above, the failure information 62 may be stored in each of the converters CELL while the abnormality of the cell voltage of each converter CELL is determined by the host controller 14 or the like. Even in this case, the configuration of the host controller 14 can be simplified as compared with the case where the host controller 14 stores the failure information 62 of each converter CELL.

  However, as shown in FIG. 5, each converter CELL is provided with a determination circuit 54 and a storage unit 60 to cause each converter CELL to determine whether the cell voltage is abnormal and to store the failure information 62. Thereby, the structure of the high-order control apparatus 14 can be simplified more.

FIG. 8 is a block diagram schematically showing a modification of the main circuit.
As illustrated in FIG. 8, in this example, the main circuit 40 includes a first switching element 41 and a second switching element 42, and further includes a third switching element 43 and a fourth switching element 44. The third switching element 43 and the fourth switching element 44 are substantially the same elements as the first switching element 41 and the second switching element 42.

  The pair of main terminals of the fourth switching element 44 are connected in series to the pair of main terminals of the third switching element 43. The third switching element 43 and the fourth switching element 44 are connected in parallel to the first switching element 41 and the second switching element 42. The charge storage element 45 is connected in parallel to the first switching element 41 and the second switching element 42 and is connected in parallel to the third switching element 43 and the fourth switching element 44.

  The third switching element 43 is connected with a rectifying element 43d in antiparallel with the pair of main terminals. A rectifying element 44d is connected to the fourth switching element 44 in antiparallel with the pair of main terminals.

  The first connection terminal 40 a of the converter CELL is connected between the first switching element 41 and the second switching element 42. The second connection terminal 40 b is connected between the third switching element 43 and the fourth switching element 44. In this example, the second connection terminal 40 b is connected to the main terminal opposite to the main terminal connected to the second switching element 42 of the first switching element 41 via the third switching element 43. In this example, the switching elements 41 to 44 are connected by a full bridge.

  That is, the main circuit 40 in this example is a so-called full bridge circuit. Thus, the main circuit 40 used for each converter CELL of the MMC type power converter 10 may be a chopper circuit or a full bridge circuit.

  Although not shown in FIG. 8 for the sake of convenience, the third switching element 43 and the fourth switching element 44 are turned on / off by the control unit 46 in the same manner as the first switching element 41 and the second switching element 42. Controlled. The converter CELL includes, for example, four gate circuits corresponding to the switching elements 41 to 44, respectively. The control unit 46 controls the operation of each gate circuit based on the control signal input from the host controller 14. Thereby, ON / OFF of each switching element 41-44 is controlled.

  In each of the above embodiments, an MMC type power converter is used for the main circuit unit 12. The main circuit unit 12 is not limited to the MMC type, and may be another type of power converter in which a plurality of converters CELL are connected in series.

  The power conversion device 10 is not limited to a DC power transmission system, and may be applied to other arbitrary systems that require conversion from AC to DC and conversion from DC to AC. The AC / DC conversion by the power conversion device 10 is not limited to both AC to DC and DC to AC, and may be only one of AC to DC or DC to AC. Further, the AC power converted by the power converter 10 is not limited to three-phase AC power, and may be single-phase AC power, two-phase AC power, or the like.

  Although several embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the scope of the invention. These embodiments and modifications thereof are included in the scope and gist of the invention, and are included in the invention described in the claims and the equivalents thereof.

  DESCRIPTION OF SYMBOLS 2 ... AC power system 3, 4, DC transmission line, 6 ... Transformer, 10 ... Power converter, 12 ... Main circuit part, 14 ... High-order control device, 20a, 20b ... DC terminal, 21a-21c ... 1st -3rd AC terminal, 22a-22f ... 1st-6th arm part, 23a-23f ... Buffer reactor, 24a-24f ... Current detector, 25 ... Voltage detection part, 26 ... Signal line, 40 ... Main circuit, 41 ˜44 ... switching element, 45 ... charge storage element, 46 ... control unit, 48 ... feeding circuit, 50 ... voltage detector, 51,52 ... gate circuit, 54 ... determination circuit, 60 ... storage unit, 62 ... failure information

Claims (6)

A main circuit unit having a plurality of converters connected in series, and performing at least one of conversion from AC power to DC power and conversion from DC power to AC power by operation of the plurality of converters; ,
A host controller for controlling the operation of the plurality of converters;
With
Each of the plurality of converters is
A plurality of switching elements connected in half-bridge or full-bridge, and
A plurality of rectifier elements connected in parallel to each of the plurality of switching elements;
A charge storage element connected in parallel to the plurality of switching elements;
A control unit for controlling on / off of the plurality of switching elements;
A power supply circuit that generates a control power source for the control unit based on the charge accumulated in the charge storage element, and supplies the generated control power source to the control unit;
A voltage detector that detects a voltage of the charge storage element and outputs a detection result to the control unit and the host controller;
Have
The host controller calculates an average value of the voltages of the charge storage elements of the plurality of converters based on the detection results of the voltage detectors of the plurality of converters, and calculates the average value. Is output to the control unit of each of the plurality of converters,
The controller determines an abnormality in the voltage of the charge storage element based on the detection result of the voltage detector and the average value, and bypasses the converter determined to be abnormal when the abnormality is determined. The power converter which makes a state. The plurality of converters are modularized for at least two of the converters,
The at least two converters modularized share the detection result of the voltage detector with each other,
The control unit can determine a voltage abnormality of the charge storage element of each of the at least two converters that are modularized, and the converter determined to be abnormal can be in the bypass state. The power conversion device according to claim 1. Each of the plurality of converters has a storage unit that stores failure information indicating the state of its own failure,
The control unit is activated in response to the supply of the control power from the power supply circuit, and then refers to the failure information of the storage unit, and when the failure is stored, the conversion stored as a failure. The power converter according to claim 1 or 2 which makes a device into a bypass state. The plurality of converters are modularized for at least two of the converters,
The at least two converters modularized share the fault information with each other;
After starting, the control unit confirms the failure of each of the at least two converters modularized by referring to the failure information, and bypasses the converter stored as a failure. The power conversion device according to claim 3, which can be in a state. A main circuit unit having a plurality of converters connected in series, and performing at least one of conversion from AC power to DC power and conversion from DC power to AC power by operation of the plurality of converters; ,
A host controller for controlling the operation of the plurality of converters;
With
Each of the plurality of converters is
A plurality of switching elements connected in half-bridge or full-bridge, and
A plurality of rectifier elements connected in parallel to each of the plurality of switching elements;
A charge storage element connected in parallel to the plurality of switching elements;
A control unit for controlling on / off of the plurality of switching elements;
A power supply circuit that generates a control power source for the control unit based on the charge accumulated in the charge storage element, and supplies the generated control power source to the control unit;
A storage unit for storing failure information representing own failure;
Have
The control unit is activated in response to the supply of the control power from the power supply circuit, and then refers to the failure information of the storage unit, and when the failure is stored, the conversion stored as a failure. Power conversion device that puts the instrument in a bypass state The plurality of converters are modularized for at least two of the converters,
The at least two converters modularized share the fault information with each other;
After starting, the control unit confirms the failure of each of the at least two converters modularized by referring to the failure information, and bypasses the converter stored as a failure. The power conversion device according to claim 5, wherein the power conversion device can be in a state.

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