Power Conversion Device

Abstract

To provide a power conversion device capable of more efficiently performing inspections of a light emitting element used in optical communications.SOLUTION: There is provided a power conversion device including a main circuit part performing power conversion, and a control unit controlling the operation of the main circuit part by performing optical communications with the main circuit part. The main circuit part includes a light-emitting element which outputs optical signals to perform optical communications with the control unit, and, when transmitting predetermined transmission data from the light-emitting element to the control unit, transmits, subsequently to the transmission data, a test pattern to perform inspections of the light-emitting element, the test pattern being signals to gradually decrease an amount of light of the light-emitting element. The control unit detects deterioration of the light-emitting element when a reception period of the test pattern is equal to or less than a predetermined time.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] FIELD An embodiment of the present invention relates to a power conversion device. [Background technology]

[0002] There is a power conversion device that includes a main circuit unit that converts power and a control device that controls the operation of the main circuit unit. In such a power conversion device, optical communication is used for communication between the main circuit unit and the control device. Light-emitting elements are used for the optical communication. For example, in a large-capacity power conversion device that handles a relatively large amount of power, many light-emitting elements are used for optical communication between the main circuit unit and the control device.

[0003] The reliability required for a power conversion device is higher than that required for a light-emitting element. For example, the lifespan required for a power conversion device is longer than the lifespan of a light-emitting element. For this reason, it has been proposed that a power conversion device have a multiplexed optical communication transmission path so that, when a transmission abnormality is detected in one transmission path, operation can be continued by switching to another transmission path.

[0004] For example, two transmission paths are provided, one as the operating system and the other as the standby system, and when an abnormality is detected in the operating transmission path, the system switches to the standby transmission path. This allows operation to continue using the other transmission path even when an abnormality occurs in one transmission path.

[0005] In this case, because the power conversion device is energized while it is operating, maintenance on the abnormal transmission path after detecting a transmission abnormality cannot be performed until the operation of the power conversion device is stopped for periodic inspection or the like. For this reason, the device may be operated without a standby system. If an abnormality occurs in one of the two transmission paths and the other transmission path continues to operate, there is a possibility that the power conversion device will not be able to continue operating.

[0006] For this reason, during periodic inspections, the light intensity of the light-emitting elements is checked to inspect their lifespan. For example, after discharging the main circuit during periodic inspections, a light intensity meter is connected to the main circuit side to measure the light intensity of the light-emitting elements provided in the main circuit, thereby inspecting the lifespan of the light-emitting elements provided in the main circuit. If the end of the life of the light-emitting element (decrease in the light intensity of the light-emitting element) is detected, the light-emitting element is replaced, etc. This makes it possible to prevent abnormalities in the transmission path due to the end of the life of the light-emitting element.

[0007] However, as described above, the inspection method of connecting a light meter to measure light intensity requires an operator to connect the light meter each time, which makes the inspection time-consuming. In particular, in the case of a large-capacity power conversion device or other device with many light-emitting elements, measuring each light-emitting element takes time, which lengthens the inspection time. Furthermore, the inspection method of connecting a light meter to measure light intensity can only inspect the light-emitting elements when the power conversion device is stopped.

[0008] Therefore, in a power conversion device that uses optical communication for communication between a main circuit section and a control device, it is desirable to be able to more efficiently inspect the light-emitting elements used in the optical communication. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Publication No. 2019-140738 Summary of the Invention [Problem to be solved by the invention]

[0010] The embodiments provide a power conversion device that can more efficiently inspect light-emitting elements used in optical communications. [Means for solving the problem]

[0011] According to an embodiment, a power conversion device is provided that includes a main circuit unit that converts power and a control unit that controls the operation of the main circuit unit by optically communicating with the main circuit unit, wherein the main circuit unit has a light-emitting element that outputs an optical signal and communicates optically with the control unit, and when predetermined transmission data is sent from the light-emitting element to the control unit, a test pattern for inspecting the light-emitting element is sent following the transmission data, the test pattern is a signal that gradually reduces the light intensity of the light-emitting element, and the control unit detects deterioration of the light-emitting element when the reception period of the test pattern becomes less than a predetermined time. [Effects of the Invention]

[0012] In this embodiment, a power conversion device is provided that can more efficiently inspect light emitting elements used in optical communications. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is a block diagram schematically illustrating a power conversion device according to a first embodiment. [Figure 2] 1 is a block diagram schematically illustrating an example of an optical transmission circuit and a first optical transmission circuit according to a first embodiment. [Figure 3] 3 is a timing chart schematically illustrating an example of the operation of the power conversion device according to the first embodiment. [Figure 4] 3 is a timing chart schematically illustrating an example of the operation of the power conversion device according to the first embodiment. [Figure 5] FIG. 10 is a block diagram schematically illustrating an example of an optical transmission circuit according to a second embodiment. [Figure 6] 10 is a timing chart schematically illustrating an example of the operation of the power conversion device according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, an embodiment of the present invention will be described 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 parts, etc. are not necessarily the same as those in reality. Furthermore, even when the same part is shown, the dimensions and ratios may be different depending on the drawing. In the present specification and the drawings, elements similar to those described above with reference to the previous drawings are given the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0015] (First embodiment) FIG. 1 is a block diagram schematically illustrating a power conversion device according to a first embodiment. As shown in FIG. 1, the power conversion device 10 includes a main circuit unit 12 and a control device 14. The main circuit unit 12 converts power. The main circuit unit 12 is provided, for example, between an AC power system and a DC circuit. The main circuit unit 12 is connected to the AC power system via, for example, a transformer. The main circuit unit 12 converts power in both directions between AC power and DC power.

[0016] The main circuit unit 12 is, for example, a multilevel power converter having a plurality of converters 20 connected in series. Each converter 20 has a plurality of switching elements connected in half-bridge or full-bridge configuration, and a charge storage element connected in parallel to each switching element. The main circuit unit 12 converts power through the operation of the plurality of converters 20. The main circuit unit 12 performs AC-DC conversion, for example, by switching each switching element of the plurality of converters 20.

[0017] The main circuit unit 12 is, for example, an MMC (Modular Multilevel Converter) type power converter. The power conversion device 10 is used, for example, in a DC power transmission system. However, the configuration of the main circuit unit 12 is not limited to the above. The configuration of the main circuit unit 12 is not limited to a configuration in which multiple converters 20 are connected in series, and may be, for example, a three-phase inverter circuit or a three-level inverter circuit. The configuration of the main circuit unit 12 may be any configuration that is capable of converting power.

[0018] Furthermore, the power conversion by the main circuit unit 12 is not limited to conversion from DC power to AC power or from AC power to DC power, but may also be conversion from DC power to another DC power or from AC power to another AC power. The power conversion by the main circuit unit 12 is not limited to bidirectional conversion, but may also be unidirectional conversion. The power conversion by the main circuit unit 12 may be any conversion that converts power into another power.

[0019] The control device 14 controls the operation of the main circuit unit 12. The control device 14 controls the power conversion by the main circuit unit 12, for example, by controlling the switching of each switching element of each converter 20.

[0020] The control device 14 has a first control unit 31 and a second control unit 32. The configuration of the second control unit 32 is substantially the same as the configuration of the first control unit 31. The control device 14 controls the operation of the main circuit unit 12 using either the first control unit 31 or the second control unit 32. The control device 14 designates one of the first control unit 31 or the second control unit 32 as an operating system and the other as a standby system. This allows the standby system control unit to continue operation even when an abnormality occurs in the operating system control unit, thereby improving the reliability of the power conversion device 10.

[0021] The control device 14 controls the operation of the main circuit unit 12 by optically communicating with the main circuit unit 12. The first control unit 31 has an optical transmission circuit 33 for optically communicating with the main circuit unit 12. Similarly, the second control unit 32 has an optical transmission circuit 34 for optically communicating with the main circuit unit 12. The first control unit 31 and the second control unit 32 control the operation of the main circuit unit 12 by inputting control signals to the main circuit unit 12 by optical communication.

[0022] However, the number of control units provided in the control device 14 is not limited to two and may be three or more. The control device 14 may have two or more standby control units. Furthermore, the number of control units provided in the control device 14 may be one. The control device 14 does not necessarily have to have a standby control unit.

[0023] Each converter 20 includes, for example, a conversion circuit 40, a first optical transmission circuit 41, a second optical transmission circuit 42, a first transmission abnormality detection circuit 43, a second transmission abnormality detection circuit 44, a first switch 45, a second switch 46, and a selection circuit 47.

[0024] The conversion circuit 40 includes, for example, a plurality of switching elements connected in a half-bridge or full-bridge configuration as described above, and a charge storage element connected in parallel to each of the switching elements. The conversion circuit 40 performs power conversion by switching the plurality of switching elements.

[0025] The first optical transmission circuit 41 performs optical communication with the optical transmission circuit 33 of the first control unit 31. The first optical transmission circuit 41 inputs a control signal received from the first control unit 31 to the conversion circuit 40. As a result, the operation of the conversion circuit 40 is controlled based on the control signal received from the first control unit 31.

[0026] Furthermore, the first optical transmission circuit 41, for example, collects information necessary for controlling the conversion circuit 40 from the conversion circuit 40 and transmits the collected information as a feedback signal to the first control unit 31. The feedback signal includes information on the voltages of each unit in the conversion circuit 40, such as information on the voltages of each switching element and each charge storage element. However, the information included in the feedback signal is not limited to this, and may be any information necessary for controlling the conversion circuit 40.

[0027] The first control unit 31 generates a plurality of control signals corresponding to each of the converters 20 based on, for example, command values ​​input from a higher-level controller and feedback signals received from each converter 20, and controls the operation of each converter 20 by inputting the generated control signals to the corresponding converters 20.

[0028] The second optical transmission circuit 42 performs optical communication with the optical transmission circuit 34 of the second control unit 32. The second optical transmission circuit 42 inputs the control signal received from the second control unit 32 to the conversion circuit 40. As a result, the operation of the conversion circuit 40 is controlled based on the control signal received from the second control unit 32.

[0029] Similarly to the first optical transmission circuit 41, the second optical transmission circuit 42 transmits a feedback signal to the second control unit 32. Similarly to the first control unit 31, the second control unit 32 generates a plurality of control signals corresponding to each of the converters 20 based on, for example, a command value input from a higher-level controller or the like and a feedback signal received from each converter 20, and controls the operation of each converter 20 by inputting the generated control signals to the corresponding converters 20.

[0030] The first transmission abnormality detection circuit 43 detects an abnormality in the transmission path between the optical transmission circuit 33 and the first optical transmission circuit 41. The first transmission abnormality detection circuit 43 detects an abnormality in the transmission path, for example, when a control signal (optical signal) is not input from the first control unit 31 for a certain period of time or longer. The first transmission abnormality detection circuit 43 inputs the abnormality detection result to the selection circuit 47.

[0031] The second transmission abnormality detection circuit 44 detects an abnormality in the transmission path between the optical transmission circuit 34 and the second optical transmission circuit 42. Similar to the first transmission abnormality detection circuit 43, the second transmission abnormality detection circuit 44 detects an abnormality in the transmission path when, for example, a control signal (optical signal) is not input from the second control unit 32 for a certain period of time or longer. The second transmission abnormality detection circuit 44 inputs the abnormality detection result to the selection circuit 47.

[0032] The first switch 45 switches between a state in which a control signal can be input from the first optical transmission circuit 41 to the conversion circuit 40 and a state in which the input of a control signal from the first optical transmission circuit 41 to the conversion circuit 40 is blocked.

[0033] The second switch 46 switches between a state in which a control signal can be input from the second optical transmission circuit 42 to the conversion circuit 40 and a state in which the input of a control signal from the second optical transmission circuit 42 to the conversion circuit 40 is blocked.

[0034] The first switch 45 and the second switch 46 are, for example, in an on state where a pair of terminals are electrically connected, allowing a control signal to be input, and in an off state where the pair of terminals are open, blocking the input of a control signal.

[0035] The selection circuit 47 controls switching of the states of the first switch 45 and the second switch 46 based on the detection results of the first transmission abnormality detection circuit 43 and the second transmission abnormality detection circuit 44. In other words, the selection circuit 47 selectively switches between a state in which a control signal can be input from the first optical transmission circuit 41 to the conversion circuit 40 and a state in which a control signal can be input from the second optical transmission circuit 42 to the conversion circuit 40.

[0036] When the first control unit 31 is the operating system and the second control unit 32 is the standby system, the selection circuit 47 sets the first switch 45 to a state that allows input of a control signal and sets the second switch 46 to a state that blocks the input of a control signal. When the first transmission abnormality detection circuit 43 detects an abnormality in the transmission path while a control signal is being input from the first control unit 31, the selection circuit 47 switches the first switch 45 to a state that blocks input of a control signal and the second switch 46 to a state that allows input of a control signal.

[0037] Furthermore, when the first transmission abnormality detection circuit 43 detects an abnormality in the transmission path, the selection circuit 47 switches the states of the first switch 45 and the second switch 46 and transmits the detection of the abnormality in the transmission path to the control device 14. The detection of the abnormality in the transmission path is transmitted, for example, from the second optical transmission circuit 42 to the second control unit 32. However, even when an abnormality in the transmission path is detected, if the first optical transmission circuit 41 is capable of transmitting the abnormality in the transmission path, the transmission may be transmitted from the first optical transmission circuit 41 to the first control unit 31, or may be transmitted from both the first optical transmission circuit 41 and the second optical transmission circuit 42.

[0038] When an abnormality in the transmission path is detected in any of the multiple converters 20, the control device 14 switches the first control unit 31 to a standby system and the second control unit 32 to an operating system. The control device 14 also detects abnormalities in the transmission path, for example, in the first control unit 31 and the second control unit 32. For example, when a feedback signal (optical signal) is not input from each converter 20 for a certain period of time or longer, the first control unit 31 and the second control unit 32 detect an abnormality in the transmission path and switch between the operating system and the standby system in the same manner as above.

[0039] When the first control unit 31 is the standby system and the second control unit 32 is the operating system, the selection circuit 47 sets the first switch 45 to a state in which the input of a control signal is blocked and sets the second switch 46 to a state in which the input of a control signal is enabled. The selection circuit 47 and the control device 14 then perform the same processing as described above. In other words, the selection circuit 47 uses the first optical transmission circuit 41 when the first control unit 31 is the operating system and uses the second optical transmission circuit 42 when the second control unit 32 is the operating system.

[0040] As a result, in the power conversion device 10, even if an abnormality occurs in either the transmission path between the first control unit 31 and each converter 20 or the transmission path between the second control unit 32 and each converter 20, the operation of the main circuit unit 12 can be continued on the other transmission path.

[0041] The power conversion device 10 further includes, for example, two optical distributors 16 and 18 corresponding to the first control unit 31 and the second control unit 32 of the control device 14, respectively.

[0042] The optical distributor 16 is connected to the optical transmission circuit 33 of the first control unit 31 via an optical fiber cable. The optical distributor 16 transmits data to and from the optical transmission circuit 33. The optical distributor 16 is also connected to each first optical transmission circuit 41 of the multiple converters 20 via an optical fiber cable. The optical distributor 16 transmits data to and from each first optical transmission circuit 41 of the multiple converters 20. Therefore, the first control unit 31 transmits data to and from each first optical transmission circuit 41 of the multiple converters 20 via the optical distributor 16 and the optical fiber cable. In other words, the first control unit 31 performs optical communication with each first optical transmission circuit 41 of the multiple converters 20 via the optical distributor 16 and the optical fiber cable.

[0043] Similarly, the optical distributor 18 is connected to the optical transmission circuit 34 of the second control unit 32 via an optical fiber cable, and is also connected to each of the second optical transmission circuits 42 of the multiple converters 20 via an optical fiber cable. The second control unit 32 transmits data to and from each of the second optical transmission circuits 42 of the multiple converters 20 via the optical distributor 18 and the optical fiber cable. In other words, the second control unit 32 performs optical communication with each of the second optical transmission circuits 42 of the multiple converters 20 via the optical distributor 18 and the optical fiber cable.

[0044] The optical distributor 16 distributes the optical signal transmitted from the first control unit 31 to each of the multiple converters 20 via an optical fiber cable corresponding to each converter 20. The optical distributor 16 also combines the data of the optical signals transmitted from the multiple converters 20 into data of a single optical signal, thereby making it substantially serial data, and transmits it to the first control unit 31.

[0045] Similarly, the optical distributor 18 distributes the optical signal transmitted from the second control unit 32 to each of the multiple converters 20 via an optical fiber cable corresponding to each converter 20. The optical distributor 18 also combines the data of the optical signals transmitted from the multiple converters 20 into data of a single optical signal, thereby making it substantially serial data, and transmits it to the second control unit 32.

[0046] The optical distributors 16, 18 can be installed near the main circuit unit 12. Therefore, the optical fiber cables connecting each optical distributor 16, 18 and each converter 20 can be long enough to be laid inside the main circuit unit 12. The control device 14 can be installed in a location sufficiently distant from the main circuit unit 12 and each optical distributor 16, 18. The control device 14 is installed, for example, in a building or on a floor different from the locations where the optical distributors 16, 18 and the main circuit unit 12 are installed.

[0047] The length of the optical fiber cable connecting each of the optical distributors 16, 18 and each of the converters 20 can be made sufficiently shorter than the length of the optical fiber cable connecting each of the optical distributors 16, 18 and the control device 14. This makes it possible to shorten the total length of the optical fiber cables compared to, for example, a case where a plurality of optical fiber cables corresponding to the number of converters 20 are directly connected to the control device 14. This allows for cost reduction.

[0048] However, the power conversion device 10 does not necessarily have to include the optical distributors 16, 18. For example, a configuration may be adopted in which a plurality of optical fiber cables corresponding to the number of converters 20 are directly connected to the control device 14. In this way, the optical distributors 16, 18 are provided as needed and can be omitted.

[0049] The optical transmission circuit 33 converts, for example, serial data generated in another part of the first control unit 33 into an optical signal and transmits it to the main circuit unit 12 via the optical fiber cable and the optical distributor 16. The optical transmission circuit 34 converts, for example, serial data generated in another part of the second control unit 32 into an optical signal and transmits it to the main circuit unit 12 via the optical fiber cable and the optical distributor 18. The serial data includes control signals corresponding to each converter 20.

[0050] Furthermore, the optical transmission circuit 33 converts the optical signal received from the main circuit unit 12 into an electrical signal and supplies it to other parts of the first control unit 33. The optical transmission circuit 34 converts the optical signal received from the main circuit unit 12 into an electrical signal and supplies it to other parts of the second control unit 32. The other parts of the first control unit 31 and the second control unit 32 perform processing to generate the next control signal, etc.

[0051] The optical distributor 16, for example, combines the data of the optical signals transmitted from the multiple converters 20 into one optical signal, thereby converting the data into substantially serial data, and transmits the resulting data to the optical transmission circuit 33 of the first control unit 31. Similarly, the optical distributor 18, for example, combines the data of the optical signals transmitted from the multiple converters 20 into one optical signal, thereby converting the data into substantially serial data, and transmits the resulting data to the optical transmission circuit 34 of the second control unit 32. The power conversion device 10 employs, for example, a star-type communication system centered around the optical distributors 16 and 18. The optical distributors 16 and 18 are, in other words, repeaters. The optical distributors 16 and 18 may be replaced with, for example, star couplers.

[0052] FIG. 2 is a block diagram schematically illustrating an example of the optical transmission circuit and the first optical transmission circuit according to the first embodiment. 2 schematically shows an example of the optical transmission circuit 33 of the first control unit 31 and the first optical transmission circuit 41 of each converter 20. Note that the configuration of the optical transmission circuit 34 of the second control unit 32 is substantially the same as the configuration of the optical transmission circuit 33 of the first control unit 31, and the configuration of the second optical transmission circuit 42 of each converter 20 is substantially the same as the configuration of the first optical transmission circuit 41, so a specific description of the configurations of the optical transmission circuit 34 and the second optical transmission circuit 42 will be omitted.

[0053] As shown in FIG. 2, the first optical transmission circuit 41 of each converter 20 includes, for example, a light-emitting element 50, an optical driver 51, a transmission buffer 52, a light-receiving element 53, a reception amplifier 54, a reception buffer 55, and a device-specific transmission request detection circuit 56.

[0054] A predetermined signal generated within the converter 20 is input as transmission data to the transmission buffer 52. For example, a feedback signal recovered from the conversion circuit 40 is input as transmission data to the transmission buffer 52. The transmission buffer 52 temporarily stores the input transmission data and inputs it to the optical driver 51.

[0055] The optical driver 51 drives the light emitting element 50 to output an optical signal by switching between emitting and stopping light emission in accordance with transmission data input from the transmission buffer 52 .

[0056] The light-emitting element 50 is connected to the optical distributor 16 via an optical fiber cable, and outputs an optical signal corresponding to transmission data to the optical distributor 16 based on the driving of the optical driver 51. The light-emitting element 50 outputs an optical signal corresponding to the feedback signal to the optical distributor 16, for example, as described above.

[0057] The light receiving element 53 is connected to the optical distributor 16 via an optical fiber cable, converts the optical signal input from the optical distributor 16 into an electrical signal, and inputs it to the receiving amplifier 54 .

[0058] The receiving amplifier 54 amplifies the electrical signal input from the light receiving element 53 to restore the electrical signal input from the light receiving element 53 to the original control signal, and inputs the restored control signal to the receiving buffer 55.

[0059] The receiving buffer 55 temporarily stores the control signal input from the receiving amplifier 54 , and inputs the stored control signal to the conversion circuit 40 and also to the device's own transmission request detection circuit 56 .

[0060] The conversion circuit 40 drives a plurality of switching elements based on the input control signal, thereby controlling the power conversion by the conversion circuit 40 based on the control signal transmitted from the first control unit 31.

[0061] The own device transmission request detection circuit 56 detects whether or not the first control unit 31 is requesting its own converter 20 to transmit transmission data, based on the control signal input from the receive buffer 55. When the own device transmission request detection circuit 56 detects that transmission of transmission data is not requested, it turns off the transmission enable for the light-emitting element 50 and prohibits output of an optical signal from the light-emitting element 50. When the own device transmission request detection circuit 56 detects that transmission of transmission data is requested, it turns on the transmission enable for the light-emitting element 50 and permits output of an optical signal from the light-emitting element 50.

[0062] For example, when detecting that transmission of transmission data has been requested, the own device transmission request detection circuit 56 turns on the transmission enable for the light emitting element 50 for a predetermined period, and switches the transmission enable from on to off as the predetermined period elapses. The predetermined period may be changed arbitrarily depending on, for example, the data length of the transmission data.

[0063] In this way, the device's own transmission request detection circuit 56 switches between a state in which the output of an optical signal from the light-emitting element 50 is prohibited and a state in which the output of an optical signal from the light-emitting element 50 is permitted, based on the control signal input from the receiving buffer 55.

[0064] The light emitting element 50 outputs an optical signal when the transmission enable is on (when the output of an optical signal is permitted), and does not output an optical signal when the transmission enable is off (when the output of an optical signal is prohibited). The transmission data may be stored in advance in the transmission buffer 52, or may be generated in response to the reception of a transmission request.

[0065] The first control unit 31 sequentially requests the multiple converters 20 to transmit transmission data at different times. In response to receiving the transmission requests, the multiple converters 20 transmit optical signals to the optical splitter 16. As a result, the optical signals transmitted from each of the multiple converters 20 are input sequentially at different times to the optical splitter 16. Therefore, as described above, the optical signals transmitted from each of the multiple converters 20 are combined into one optical signal by the optical splitter 16, and are transmitted to the optical transmission circuit 33 of the first control unit 31 as substantially serial data.

[0066] Furthermore, when transmitting transmission data in response to a transmission request from the first control unit 31, the first optical transmission circuit 41 transmits a test pattern for inspecting the light-emitting element 50 following the transmission data. For example, the first optical transmission circuit 41 transmits the test pattern for a certain period of time following the transmission data. The test pattern may be transmitted every time transmission data is transmitted, or may be transmitted only at predetermined timings. The test pattern may be transmitted, for example, when the first control unit 31 requests transmission of the transmission data and the test pattern.

[0067] As shown in FIG. 2, the optical transmission circuit 33 of the first control unit 31 includes, for example, a light-emitting element 60, an optical driver 61, a transmitting buffer 62, a light-receiving element 63, a receiving amplifier 64, a receiving buffer 65, and a test pattern detector 66.

[0068] Control signals generated by other parts of the first control unit 33 are input as transmission data to the transmission buffer 62. The transmission buffer 62 temporarily stores the input transmission data and inputs it to the optical driver 61.

[0069] The optical driver 61 drives the light emitting element 60 to output an optical signal by switching between emitting and stopping light emission in accordance with the transmission data input from the transmission buffer 62 .

[0070] The light-emitting element 60 is connected to the optical distributor 16 via an optical fiber cable, and outputs an optical signal corresponding to transmission data to the optical distributor 16 based on the driving of the optical driver 61. The light-emitting element 60 outputs an optical signal corresponding to a control signal to the optical distributor 16, for example, as described above. As a result, the optical signal (control signal) output from the light-emitting element 60 of the optical transmission circuit 33 of the first control unit 31 is input to the light-receiving element 53 of the first optical transmission circuit 41 of each converter 20 via the optical distributor 16.

[0071] The light receiving element 63 is connected to the optical distributor 16 via an optical fiber cable and receives an optical signal input from the optical distributor 16. As a result, an optical signal (e.g., a feedback signal) output from the light emitting element 50 of the first optical transmission circuit 41 of each converter 20 is input to the light receiving element 63 of the optical transmission circuit 33 of the first control unit 31 via the optical distributor 16. The light receiving element 63 converts the optical signal input from the optical distributor 16 into an electrical signal and inputs it to the receiving amplifier 64.

[0072] The receiving amplifier 64 amplifies the electrical signal input from the light receiving element 63 to restore the electrical signal input from the light receiving element 63 to the original signal (e.g., a feedback signal), and inputs the restored signal to the receiving buffer 65.

[0073] The receiving buffer 65 temporarily stores the signal input from the receiving amplifier 64, and inputs the stored signal to other parts of the first control unit 33 (for example, a circuit that generates a control signal), as well as to the test pattern detector 66.

[0074] As described above, the first control unit 31 generates a plurality of control signals corresponding to each of the converters 20 based on, for example, command values ​​input from a higher-level controller and feedback signals received from each converter 20, and controls the operation of each converter 20 by inputting the generated control signals to the corresponding converters 20.

[0075] The test pattern detector 66 detects the test pattern transmitted from the first optical transmission circuit 41 of each converter 20 based on the signal input from the receiving buffer 65, and inspects the light-emitting element 50 provided in the converter 20 that is the transmission source based on the detected test pattern. In other words, the test pattern detector 66 detects deterioration of the light-emitting element 50 provided in the converter 20 that is the transmission source based on the detected test pattern.

[0076] FIG. 3 is a timing chart schematically illustrating an example of the operation of the power conversion device according to the first embodiment. 3 schematically shows an example of the operation of the optical transmission circuit 33 of the first control unit 31 and the first optical transmission circuit 41 of each converter 20. Note that the operation of the optical transmission circuit 34 of the second control unit 32 and the second optical transmission circuit 42 of each converter 20 is substantially the same as the operation of the optical transmission circuit 33 of the first control unit 31 and the first optical transmission circuit 41 of each converter 20, and therefore a detailed description thereof will be omitted.

[0077] 3, the first control unit 31 sequentially requests the plurality of converters 20 to transmit transmission data at different times. The transmission request for transmission data includes, for example, identification information for identifying the plurality of converters 20. Each converter 20 determines whether the transmission request is directed to itself based on the identification information included in the transmission request.

[0078] Each converter 20 transmits transmission data to the first control unit 31 in response to receiving a transmission request addressed to itself, and transmits a test pattern following the transmission data to the first control unit 31. The transmission data transmitted as optical signals from each converter 20 are combined into one optical signal by the optical distributor 16, and are transmitted to the optical transmission circuit 33 of the first control unit 31 as substantially serial data.

[0079] FIG. 4 is a timing chart schematically illustrating an example of the operation of the power conversion device according to the first embodiment. 4 shows examples of the transmission enable input from the device's own transmission request detection circuit 56 to the light-emitting element 50, the transmission signal input to the transmission buffer 52, the optical output signal output from the light-emitting element 50 based on the transmission signal, the optical reception signal received by the light-receiving element 63 of the first control unit 31, and the reception signal output from the reception amplifier 64 based on the optical reception signal in a given converter 20. Also, FIG. 4 shows examples of each signal in the initial state and each signal in an aged deterioration state.

[0080] 4, when the first control unit 31 requests a predetermined converter 20 to transmit transmission data, the transmission request for the transmission data is detected by the local transmission request detection circuit 56, a predetermined transmission signal is input to the transmission buffer 52, and the transmission enable for the light-emitting element 50 is switched from off to on. The transmission signal includes a signal representing the transmission data and a signal representing a test pattern provided following the transmission data.

[0081] When the transmission enable is switched on, an optical output signal corresponding to the transmission signal input to the transmission buffer 52 is output from the light emitting element 50 based on the driving of the optical driver 51. As a result, the transmission data and the test pattern are transmitted to the first control unit 31.

[0082] It may take time for the optical output signal to become a stable output. In other words, it may take time for the light-emitting element 50 to emit a stable amount of light. For this reason, the optical output signal gradually increases from the timing when the transmission enable is turned on to reach a predetermined output. The light-emitting element 50 gradually increases from the timing when the transmission enable is turned on to reach a predetermined amount of light.

[0083] The transmission data is, for example, a pulse signal. The transmission data is, for example, a digital signal that represents the digital values ​​"0" and "1" by emitting light from the light-emitting element 50 and stopping the emission of light from the light-emitting element 50. The transmission data represents, for example, the content of the feedback signal by a digital signal.

[0084] The test pattern is, for example, a pulsed signal that repeatedly turns on and off at a predetermined cycle. As shown in FIG. 4, the test pattern is a signal that gradually reduces the light intensity of the light-emitting element 50. For example, the first optical transmission circuit 41 (own device transmission request detection circuit 56) switches the transmission enable for the light-emitting element 50 from on to off while transmitting the test pattern. When the transmission enable is switched from on to off, the light intensity of the light-emitting element 50 does not decrease suddenly, but gradually. This makes it possible to transmit a test pattern that gradually reduces the light intensity of the light-emitting element 50.

[0085] However, the method of transmitting the test pattern by gradually reducing the light intensity of the light-emitting element 50 is not limited to the above. For example, the light intensity of the light-emitting element 50 may be gradually reduced by gradually reducing the voltage applied to the light-emitting element 50 while transmitting the test pattern. The method of transmitting the test pattern may be any method that can gradually reduce the light intensity of the light-emitting element 50.

[0086] As described above, the first control unit 31 generates a control signal for the corresponding converter 20 based on the transmission data received by the light receiving element 63. The first control unit 31 recognizes the content of the feedback signal, etc., based on the transmission data, for example, a digital signal.

[0087] 4, the optical output signal output from the light-emitting element 50 of the converter 20 gradually decreases due to aging. Therefore, when a test pattern that gradually decreases the light intensity of the light-emitting element 50 is transmitted, the reception period of the test pattern received by the light-receiving element 63 of the optical transmission circuit 33 of the first control unit 31 becomes shorter in accordance with the decrease in the optical output signal due to aging of the light-emitting element 50.

[0088] The test pattern detector 66 detects deterioration of the light-emitting element 50 provided in the converter 20 that is the sender based on changes in the reception period of the test pattern. The test pattern detector 66 detects deterioration of the light-emitting element 50 provided in the converter 20 that is the sender when the reception period of the test pattern becomes equal to or shorter than a predetermined time. The test pattern detector 66 may, for example, set multiple thresholds for the reception period of the test pattern and detect the degree of deterioration of the light-emitting element 50 in stages depending on the length of the reception period of the test pattern.

[0089] For example, when the test pattern detector 66 detects deterioration of the light-emitting element 50 of any of the multiple converters 20, the first control unit 31 notifies the user of the detection of deterioration of the light-emitting element 50 of the corresponding converter 20. The first control unit 31 (control device 14) has, for example, a display unit (not shown), and notifies the user of the detection of deterioration of the light-emitting element 50 of the corresponding converter 20 by displaying the detection of deterioration of the light-emitting element 50 of the corresponding converter 20 on the display unit. This makes it possible to appropriately notify an operator or the like of the detection of deterioration of the light-emitting element 50 of a specific converter 20.

[0090] However, the manner of notifying the detection of deterioration of the light-emitting element 50 is not limited to the above. For example, the detection of deterioration of the light-emitting element 50 may be notified by transmitting information to a mobile terminal carried by a worker or the like, such as a smartphone or tablet terminal, and displaying the information on a display unit of the mobile terminal. The manner of notifying the detection of deterioration of the light-emitting element 50 may be any manner that can appropriately notify the worker or the like of the detection of deterioration of the light-emitting element 50.

[0091] The control device 14 may, for example, store information on the detection of deterioration of the light-emitting element 50, and may display the detection of deterioration of the light-emitting element 50 on a display unit or the like based on an operation by an operator or the like. The control device 14 does not necessarily have to automatically notify the detection of deterioration of the light-emitting element 50 in response to the detection of deterioration of the light-emitting element 50.

[0092] In addition, the control device 14 may switch between the operating system and standby system of the first control unit 31 and the second control unit 32, for example, when deterioration of the light-emitting element 50 of a specified converter 20 is detected in the operating system of the first control unit 31 and the second control unit 32.

[0093] As described above, in the power conversion device 10 according to this embodiment, the main circuit unit 12 has the light emitting element 50 for outputting an optical signal to perform optical communication with the control device 14, and when predetermined transmission data is transmitted from the light emitting element 50 to the control device 14, a test pattern for inspecting the light emitting element 50 is transmitted following the transmission data. The test pattern is a signal that gradually reduces the light intensity of the light emitting element 50, and the control device 14 detects deterioration of the light emitting element 50 when the period for receiving the test pattern becomes equal to or shorter than a predetermined time.

[0094] As a result, the power conversion device 10 according to this embodiment can reduce the time and effort required to connect a light intensity meter to the main circuit unit 12 and measure the light intensity of the light-emitting element 50 one by one. The power conversion device 10 according to this embodiment can detect deterioration of the light-emitting element 50 while voltage is being applied to the main circuit unit 12. Therefore, the power conversion device 10 according to this embodiment can more efficiently inspect the light-emitting element 50 used in optical communication.

[0095] Furthermore, in the power conversion device 10 according to this embodiment, for example, during periodic inspection, it is only necessary to perform maintenance such as inspection and replacement of light-emitting elements 50 for which deterioration has been detected, thereby eliminating the need to inspect all of the light-emitting elements 50. Therefore, even when the main circuit unit 12 has a plurality of light-emitting elements 50, the labor required to inspect the plurality of light-emitting elements 50 can be reduced compared to, for example, connecting a light intensity meter to measure the light intensity of the plurality of light-emitting elements 50 provided in each of the plurality of converters 20 one by one and inspecting the plurality of light-emitting elements 50. For example, the time required for one inspection can also be shortened.

[0096] (Second embodiment) FIG. 5 is a block diagram schematically illustrating an example of an optical transmission circuit according to the second embodiment. 5 is a schematic diagram showing an example of the optical transmission circuit 34 of the second control unit 32. Components that are substantially the same in function and configuration as those in the first embodiment are given the same reference numerals, and detailed descriptions thereof will be omitted.

[0097] 5, in this example, the optical transmission circuit 34 of the second control unit 32 further includes a light amount meter 67. In this example, the light receiving element 63 converts the optical signal input from each converter 20 via the optical distributor 16 into an electrical signal, and inputs the electrical signal to the receiving amplifier 64 and the light amount meter 67.

[0098] The light quantity meter 67 measures the light quantity (optical power) of the light emitting element 50 of the converter 20 based on the electrical signal input from the light receiving element 63. The light quantity meter 67 measures, for example, the average value of the light quantity of the light emitting element 50 of the converter 20. The light quantity meter 67 measures, for example, the average value of the light quantity of the pulsed optical signal output from the light emitting element 50 of the converter 20.

[0099] The light quantity meter 67 may measure, for example, the peak value of the light quantity of the light-emitting element 50 of the converter 20. However, a method of detecting the peak value (peak power) requires high-speed detection and processing, which may result in increased complexity and cost of the device. As described above, by measuring the average value of the light quantity of the light-emitting element 50, it is possible to appropriately measure the light quantity of the light-emitting element 50 while suppressing the increase in complexity and cost of the device.

[0100] The light quantity meter 67 inspects the light emitting element 50 provided in the transmitter converter 20 based on the measured light quantity of the light emitting element 50. In other words, the light quantity meter 67 detects deterioration of the light emitting element 50 provided in the transmitter converter 20 based on the measured light quantity of the light emitting element 50. The light quantity meter 67 detects deterioration of the light emitting element 50 provided in the transmitter converter 20 when the measured light quantity of the light emitting element 50 falls below a predetermined value.

[0101] FIG. 6 is a timing chart 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 optical transmission circuit 34 of the second control unit 32 and the second optical transmission circuit 42 of each converter 20. In FIG.

[0102] When in standby mode, the second control unit 32 requests the multiple converters 20 to transmit signals for measuring light power, as shown in Fig. 6. The transmission requests for signals for measuring light power output from the optical transmission circuit 34 of the second control unit 32 are input to the second optical transmission circuits 42 of each of the multiple converters 20 via the optical distributor 18. The transmission requests for signals for measuring light power include, for example, identification information for identifying the multiple converters 20. Each converter 20 determines whether the transmission request is directed to itself based on the identification information included in the transmission request.

[0103] In response to receiving a request to send a signal for measuring light intensity to itself, each converter 20 transmits a signal for measuring light intensity from the light-emitting element 50 of the second optical transmission circuit 42 corresponding to the second control unit 32 to the second control unit 32.

[0104] When the optical transmission circuit 34 of the second control unit 32 receives a signal for measuring light intensity from each converter 20, the optical transmission circuit 34 inputs the received signal for measuring light intensity to the light intensity meter 67, thereby detecting deterioration of the light-emitting element 50 provided in the converter 20 that sent the signal.

[0105] In the configuration of the power conversion device 10, when the second control unit 32 is a standby control unit, the second control unit 32 can freely communicate with the second optical transmission circuit 42 of each converter 20 via the optical distributor 18. In this example, this is utilized to detect deterioration of the light-emitting element 50 provided in the optical transmission circuit corresponding to the standby control unit of each converter 20.

[0106] As described above, in this example, the standby control unit out of the first control unit 31 and the second control unit 32 requests the main circuit unit 12 to transmit a signal for measuring the amount of light. The main circuit unit 12 transmits the signal for measuring the amount of light from the light-emitting element 50 of the optical transmission circuit that corresponds to the standby control unit out of the first optical transmission circuit 41 and the second optical transmission circuit 42. The standby control unit measures the amount of light from the light-emitting element 50 based on the received signal for measuring the amount of light.

[0107] As a result, in this embodiment, inspection of the light-emitting elements 50 provided in the optical transmission circuit corresponding to the standby system control unit of the main circuit unit 12 (each converter 20) can be performed more efficiently. In this embodiment, by measuring the light intensity of the light-emitting elements 50 provided in the optical transmission circuit corresponding to the standby system control unit of each converter 20, for example, deterioration transition data of the light-emitting elements 50 can be obtained, which can be used as maintenance and inspection data for the light-emitting elements 50. The control device 14, for example, stores the measurement results of the light intensity of the light-emitting elements 50 as deterioration transition data.

[0108] 6, the second control unit 32 sequentially requests the plurality of converters 20 to transmit signals for measuring light intensity at different times. Furthermore, the second control unit 32 transmits a request to transmit a signal for measuring light intensity multiple times in succession to one converter 20 out of the plurality of converters 20.

[0109] The light quantity measuring device 67 measures the average light quantity of the light emitting element 50 of the converter 20, for example, based on a light quantity measurement signal transmitted multiple times in succession from the converter 20. When the average light quantity of the measured light emitting element 50 falls below a predetermined value, the light quantity measuring device 67 detects deterioration of the light emitting element 50 provided in the converter 20 that sent the signal.

[0110] As described above, when multiple converters 20 are sequentially requested to transmit signals for measuring light power with a time lag, it may be difficult to properly measure the average light power of the light-emitting element 50 with a single transmission (single packet) of the signal for measuring light power. Therefore, in such a case, as described above, a request to transmit a signal for measuring light power is continuously transmitted multiple times to one converter 20, and the average light power of the light-emitting element 50 (the light-emitting element 50 of the first optical transmission circuit 41 or the second optical transmission circuit 42) of the converter 20 is measured based on the signal for measuring light power transmitted multiple times from one converter 20. This allows the light power of the light-emitting element 50 to be more properly measured. In other words, deterioration of the light-emitting element 50 can be more properly detected. In this case, the number of times that the signal for measuring light power is continuously transmitted may be any number of times that allows the average light power of the light-emitting element 50 to be properly measured.

[0111] As for the control unit of the operation system, the control device 14 detects deterioration of the light-emitting element 50 provided in the transmitting converter 20 based on changes in the reception period of the test pattern transmitted from each converter 20, for example, as in the first embodiment described above.

[0112] The control device 14 may measure the light intensity of each of the light-emitting elements 50 of the first optical transmission circuit 41 and the second optical transmission circuit 42 of each converter 20, for example, by switching between the operating system and the standby system of the first control unit 31 and the second control unit 32 at a predetermined timing. The timing of switching between the operating system and the standby system may be changed as appropriate depending on the operating status of the operating system, etc. The timing of switching between the operating system and the standby system may be any timing at which switching is possible.

[0113] Furthermore, when switching between the operating system and the standby system of the first control unit 31 and the second control unit 32, the optical transmission circuits 33, 34 of the first control unit 31 and the second control unit 32 do not need to have the test pattern detector 66. In other words, it is possible to measure only the light intensity of the light-emitting element 50 in the standby system.

[0114] Although several embodiments of the present invention have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, as well as within the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments can be implemented in combination with each other. [Explanation of symbols]

[0115] 10...power conversion device, 12...main circuit section, 14...control device, 16, 18...optical distributor, 20...converter, 31...first control section, 32...second control section, 33, 34...optical transmission circuit, 41...first optical transmission circuit, 42...second optical transmission circuit, 43...first transmission abnormality detection circuit, 44...second transmission abnormality detection circuit, 45...first switch, 46...second switch, 47...selection circuit, 50...light-emitting element, 51...optical driver, 52...transmitting buffer, 53...light-receiving element, 54...receiving amplifier, 55...receiving buffer, 56...own device transmission request detection circuit, 60...light-emitting element, 61...optical driver, 62...transmitting buffer, 63...light-receiving element, 64...receiving amplifier, 65...receiving buffer, 66...test pattern detector, 67...light amount meter

Claims

1. a main circuit section that converts power; a control device that controls the operation of the main circuit unit by optically communicating with the main circuit unit; Equipped with the main circuit unit has a light-emitting element for outputting an optical signal to perform optical communication with the control device, and when transmitting predetermined transmission data from the light-emitting element to the control device, transmits a test pattern for inspecting the light-emitting element following the transmission data; the test pattern is a signal that gradually reduces the light amount of the light-emitting element, The control device detects deterioration of the light-emitting element when the period of reception of the test pattern becomes equal to or shorter than a predetermined time.

2. the control device has a first control unit and a second control unit, one of the first control unit and the second control unit being an operating system and the other being a standby system; the main circuit unit has a first optical transmission circuit for performing optical communication with the first control unit and a second optical transmission circuit for performing optical communication with the second control unit, the light-emitting element is provided in each of the first optical transmission circuit and the second optical transmission circuit, a standby control unit of the first control unit and the second control unit requests the main circuit unit to transmit a signal for measuring the amount of light; the main circuit unit transmits the light quantity measurement signal from the light emitting element of the optical transmission circuit corresponding to the standby system control unit out of the first optical transmission circuit and the second optical transmission circuit; The power conversion device according to claim 1 , wherein the standby system control unit measures the light intensity of the light-emitting element based on the received signal for measuring the light intensity.

3. 3. The power conversion device according to claim 2, wherein the control device measures the light intensity of the light-emitting element of each of the first optical transmission circuit and the second optical transmission circuit by switching between the operating system and the standby system of the first control unit and the second control unit at a predetermined timing.

4. the main circuit unit has a plurality of converters connected in series, the first optical transmission circuit and the second optical transmission circuit are provided in each of the plurality of converters; the first control unit performs optical communication with the first optical transmission circuits of the plurality of converters via an optical distributor; the second control unit performs optical communication with the second optical transmission circuits of the plurality of converters via an optical distributor; 4. The power conversion device according to claim 2, wherein the standby system control unit sequentially requests the plurality of converters to transmit the light power measurement signal at different times, and transmits a request to transmit the light power measurement signal multiple times in succession to one of the plurality of converters, and measures an average light power of the light-emitting element of the one converter based on the light power measurement signal transmitted multiple times in succession from the one converter.

5. a main circuit section that converts power; a control device that controls the operation of the main circuit unit by optically communicating with the main circuit unit; Equipped with the main circuit unit has a light emitting element for outputting an optical signal to perform optical communication with the control device, the control device has a first control unit and a second control unit, one of the first control unit and the second control unit being an operating system and the other being a standby system; the main circuit unit has a first optical transmission circuit for performing optical communication with the first control unit and a second optical transmission circuit for performing optical communication with the second control unit, the light-emitting element is provided in each of the first optical transmission circuit and the second optical transmission circuit, a standby control unit of the first control unit and the second control unit requests the main circuit unit to transmit a signal for measuring the amount of light; the main circuit unit transmits the light quantity measurement signal from the light emitting element of the optical transmission circuit corresponding to the standby system control unit out of the first optical transmission circuit and the second optical transmission circuit; The standby system control unit is a power conversion device that measures the light intensity of the light-emitting element based on the received light intensity measurement signal.

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