JP7761362B2 - Power Conversion Device - Google Patents

Description

An embodiment of the present invention relates to a power conversion device.

Power conversion devices include a main circuit section that converts power and a control device that controls the operation of the main circuit section. In such power conversion devices, optical communication is used for communication between the main circuit section and the control device. Light-emitting elements are used for optical communication. For example, in large-capacity power conversion devices that handle relatively large amounts of power, many light-emitting elements are used for optical communication between the main circuit section and the control device.

The reliability required of power conversion devices is higher than the reliability of light-emitting elements. For example, the lifespan required of power conversion devices is longer than the lifespan of light-emitting elements. For this reason, it has been proposed that power conversion devices have multiple optical communication transmission paths so that, when a transmission abnormality is detected on one transmission path, operation can be continued by switching to another transmission path.

For example, two transmission paths are provided, one as the operating system and the other as the standby system, and if 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 if an abnormality occurs in one transmission path.

In this case, because the power conversion device is energized while it is operating, maintenance on the transmission path that has detected a transmission abnormality cannot be performed until the power conversion device is shut down for periodic inspection or other reasons. For this reason, it is sometimes operated without a standby system. If an abnormality occurs on one of two transmission paths, and the other transmission path continues to operate, and an abnormality also occurs on the other transmission path, there is a possibility that the power conversion device will not be able to continue operating.

For this reason, during regular inspections, the light intensity of the light-emitting elements is checked to inspect their lifespan. For example, after discharging the main circuit during regular inspections, a light intensity meter is connected to the main circuit and the light intensity of the light-emitting elements installed in the main circuit is measured to inspect the lifespan of the light-emitting elements installed in the main circuit. If the lifespan of a light-emitting element (a decrease in the light intensity of the light-emitting element) is detected, the light-emitting element is replaced, etc. This can prevent abnormalities in the transmission path due to the lifespan of the light-emitting element.

However, as mentioned above, the inspection method of connecting a light meter to measure light intensity requires an operator to connect the light meter each time, making the inspection time-consuming. In particular, in the case of a large-capacity power conversion device or other equipment with many light-emitting elements, measuring each light-emitting element takes time, lengthening the inspection time. Furthermore, with the inspection method of connecting a light meter to measure light intensity, the light-emitting elements can only be inspected when the power conversion device is stopped.

For this reason, in power conversion devices that use optical communication for communication between the main circuit section and the control device, it is desirable to be able to more efficiently inspect the light-emitting elements used in the optical communication.

Japanese Patent Application Laid-Open No. 2019-140738

Embodiments provide a power conversion device that enables more efficient inspection of light-emitting elements used in optical communications.

According to one 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. The main circuit unit has a light-emitting element that outputs an optical signal to optically communicate with the control unit. When predetermined transmission data is transmitted from the light-emitting element to the control unit, a test pattern for inspecting the light-emitting element is transmitted following the transmission data. The test pattern is a signal that gradually reduces the light output of the light-emitting element. The control unit detects deterioration of the light-emitting element when the reception period of the test pattern becomes equal to or shorter than a predetermined time.

This embodiment provides a power conversion device that allows for more efficient inspection of light-emitting elements used in optical communications.

1 is a block diagram schematically illustrating a power conversion device according to a first embodiment. FIG. 2 is a block diagram schematically illustrating an example of an optical transmission circuit and a first optical transmission circuit according to the first embodiment. 4 is a timing chart schematically illustrating an example of an operation of the power conversion device according to the first embodiment. 4 is a timing chart schematically illustrating an example of an operation of the power conversion device according to the first embodiment. FIG. 10 is a block diagram schematically illustrating an example of an optical transmission circuit according to a second embodiment. 10 is a timing chart schematically illustrating an example of an operation of the power conversion device according to the second embodiment.

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.

(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 bidirectionally between AC power and DC power.

The main circuit unit 12 is, for example, a multilevel power converter having multiple converters 20 connected in series. Each converter 20 has multiple 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 multiple converters 20. The main circuit unit 12 performs AC/DC conversion, for example, by switching each switching element of the multiple converters 20.

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.

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.

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.

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 the operating system and the other as the standby system. This allows operation to continue using the standby system control unit even if an abnormality occurs in the operating system control unit, improving the reliability of the power conversion device 10.

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 via optical communication.

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. The number of control units provided in the control device 14 may also be one. The control device 14 does not necessarily have to have a standby control unit.

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.

The conversion circuit 40 has, for example, multiple switching elements connected in a half-bridge or full-bridge configuration as described above, and charge storage elements connected in parallel to each switching element. The conversion circuit 40 converts power by switching the multiple switching elements.

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 the control signal received from the first control unit 31 to the conversion circuit 40. This controls the operation of the conversion circuit 40 based on the control signal received from the first control unit 31.

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 to the first control unit 31 as a feedback signal. The feedback signal includes information on the voltages of each component within 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.

The first control unit 31 generates multiple control signals corresponding to each converter 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 multiple control signals to the corresponding converter 20.

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. This controls the operation of the conversion circuit 40 based on the control signal received from the second control unit 32.

Furthermore, the second optical transmission circuit 42, like the first optical transmission circuit 41, transmits a feedback signal to the second control unit 32. Similar to the first control unit 31, the second control unit 32 generates multiple control signals corresponding to each converter 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 multiple control signals to the corresponding converter 20.

The first transmission abnormality detection circuit 43 detects abnormalities 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.

The second transmission abnormality detection circuit 44 detects abnormalities 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.

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.

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.

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 the input of a control signal, and in an OFF state where the pair of terminals are open, blocking the input of a control signal.

The selection circuit 47 controls the 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.

When the first control unit 31 is the operating system and the second control unit 32 is the standby system, the selection circuit 47 switches the first switch 45 to a state that allows the input of a control signal and switches 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 the input of a control signal and the second switch 46 to a state that allows the input of a control signal.

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.

When a transmission path abnormality is detected in any of the multiple converters 20, the control device 14 switches the first control unit 31 to the standby system and the second control unit 32 to the operating system. The control device 14 also detects transmission path abnormalities in, for example, 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 a transmission path abnormality and switch between the operating system and the standby system in the same manner as above.

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 that blocks the input of control signals and sets the second switch 46 to a state that allows the input of control signals. The selection circuit 47 and the control device 14 then perform the same processing as 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.

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 main circuit unit 12 can continue to operate via the other transmission path.

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.

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 the first optical transmission circuit 41 of each of the multiple converters 20 via an optical fiber cable. The optical distributor 16 transmits data to and from the first optical transmission circuit 41 of each of the multiple converters 20. Therefore, the first control unit 31 transmits data to and from the first optical transmission circuit 41 of each 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 the first optical transmission circuit 41 of each of the multiple converters 20 via the optical distributor 16 and the optical fiber cable.

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 the second optical transmission circuits 42 of each of the multiple converters 20 via an optical fiber cable. The second control unit 32 transmits data to and from the second optical transmission circuits 42 of each 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 the second optical transmission circuits 42 of each of the multiple converters 20 via the optical distributor 18 and the optical fiber cable.

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 each optical signal transmitted from the multiple converters 20 into a single optical signal, essentially converting it into serial data, which is then transmitted to the first control unit 31.

Similarly, the optical distributor 18 distributes the optical signal transmitted from the second control unit 32 to each of the multiple converters 20 via the optical fiber cable corresponding to each converter 20. The optical distributor 18 also combines the data of each optical signal transmitted from the multiple converters 20 into a single optical signal, essentially converting it into serial data, which is then transmitted to the second control unit 32.

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 within 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 different floor from the locations of the optical distributors 16, 18 and main circuit unit 12.

The length of the optical fiber cable connecting each optical distributor 16, 18 and each converter 20 can be made much shorter than the length of the optical fiber cable connecting each optical distributor 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, connecting multiple optical fiber cables corresponding to the number of converters 20 directly to the control device 14. This allows for cost reductions.

However, the power conversion device 10 does not necessarily have to include optical distributors 16, 18. For example, it may be configured so that multiple 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.

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 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 optical distributor 18. The serial data includes control signals corresponding to each converter 20.

In addition, 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. Other parts of the first control unit 31 and the second control unit 32 perform processing to generate the next control signal, etc.

The optical distributor 16, for example, combines the data of each optical signal transmitted from the multiple converters 20 into a single optical signal, thereby converting it into substantially serial data, and transmits it to the optical transmission circuit 33 of the first control unit 31. Similarly, the optical distributor 18, for example, combines the data of each optical signal transmitted from the multiple converters 20 into a single optical signal, thereby converting it into substantially serial data, and transmits it 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.

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 detailed description of the configurations of the optical transmission circuit 34 and the second optical transmission circuit 42 will be omitted.

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.

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

The optical driver 51 drives the output of an optical signal by the light-emitting element 50 by switching the light-emitting element 50 on and off depending on the transmission data input from the transmission buffer 52.

The light-emitting element 50 is connected to the optical distributor 16 via an optical fiber cable, and outputs an optical signal corresponding to the transmission data to the optical distributor 16 based on the drive 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.

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

The receiving amplifier 54 amplifies the electrical signal input from the light receiving element 53, thereby restoring 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.

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 the device's own transmission request detection circuit 56.

The conversion circuit 40 drives multiple switching elements based on the input control signal. This controls the power conversion by the conversion circuit 40 based on the control signal sent from the first control unit 31.

The device's own transmission request detection circuit 56 detects whether 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. If the device's own transmission request detection circuit 56 detects that transmission of transmission data is not being requested, it turns off the transmission enable for the light-emitting element 50 and prohibits the output of an optical signal from the light-emitting element 50. If the device's own transmission request detection circuit 56 detects that transmission of transmission data has been requested, it turns on the transmission enable for the light-emitting element 50 and permits the output of an optical signal from the light-emitting element 50.

For example, when the device's own transmission request detection circuit 56 detects that transmission of transmission data has been requested, it turns on the transmission enable for the light-emitting element 50 for a predetermined period of time, and switches the transmission enable from on to off after the predetermined period has elapsed. The predetermined period may be changed arbitrarily depending on, for example, the data length of the transmission data.

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.

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.

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 distributor 16. As a result, the optical signals transmitted from each of the multiple converters 20 are input to the optical distributor 16 at different times. Therefore, as described above, the optical signals transmitted from each of the multiple converters 20 are combined into a single optical signal by the optical distributor 16, and are transmitted as essentially serial data to the optical transmission circuit 33 of the first control unit 31.

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. The first optical transmission circuit 41, for example, transmits a 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 times. The test pattern may be transmitted, for example, when the first control unit 31 requests transmission of the transmission data and the test pattern.

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 transmission buffer 62, a light-receiving element 63, a reception amplifier 64, a reception buffer 65, and a test pattern detector 66.

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

The optical driver 61 drives the output of an optical signal by the light-emitting element 60 by switching the light-emitting element 60 on and off depending on the transmission data input from the transmission buffer 62.

The light-emitting element 60 is connected to the optical distributor 16 via an optical fiber cable and outputs an optical signal corresponding to the transmission data to the optical distributor 16 based on the drive of the optical driver 61. The light-emitting element 60 outputs an optical signal corresponding to the 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.

The light receiving element 63 is connected to the optical distributor 16 via an optical fiber cable and receives the optical signal input from the optical distributor 16. As a result, the 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.

The receiving amplifier 64 amplifies the electrical signal input from the light receiving element 63, thereby restoring 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.

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, the circuit that generates the control signal), as well as to the test pattern detector 66.

As described above, the first control unit 31 generates multiple control signals corresponding to each converter 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 multiple control signals to the corresponding converter 20.

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 source of transmission 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 source of transmission based on the detected test pattern.

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.

As shown in FIG. 3, the first control unit 31 sequentially requests the multiple converters 20 to transmit transmission data at different times. The transmission request for transmission data includes, 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.

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

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 an initial state and each signal in an aged deterioration state.

As shown in FIG. 4, when the first control unit 31 requests a specific converter 20 to transmit transmission data, the transmission request for transmission data is detected by the device's own transmission request detection circuit 56, a specific 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.

When the transmit enable is switched on, an optical output signal corresponding to the transmit signal input to the transmit buffer 52 is output from the light-emitting element 50 based on the drive of the optical driver 51. This causes the transmit data and test pattern to be sent to the first control unit 31.

Note that it may take time for the optical output signal to stabilize. In other words, it may take time for the light emission amount of the light-emitting element 50 to stabilize. For this reason, the optical output signal gradually increases from the timing when the transmission enable is turned on until it reaches a predetermined output. The light emission amount of the light-emitting element 50 gradually increases from the timing when the transmission enable is turned on until it reaches a predetermined light amount.

The transmission data is, for example, a pulsed signal. The transmission data is, for example, a digital signal that represents the digital values "0" and "1" by the emission of the light-emitting element 50 and the cessation of emission of the light-emitting element 50. The transmission data represents, for example, the contents of the feedback signal as a digital signal.

The test pattern is, for example, a pulsed signal that repeatedly turns on and off at a predetermined cycle. As shown in Figure 4, the test pattern is a signal that gradually reduces the light output of the light-emitting element 50. 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, for example, while transmitting the test pattern. When the transmission enable is switched from on to off, the light output 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 output of the light-emitting element 50.

However, the method of transmitting a test pattern that gradually reduces the light output of the light-emitting element 50 is not limited to the above. For example, the light output of the light-emitting element 50 may be gradually reduced by gradually reducing the voltage applied to the light-emitting element 50 while the test pattern is being transmitted. The method of transmitting a test pattern may be any method that can gradually reduce the light output of the light-emitting element 50.

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, which is, for example, a digital signal.

As shown in FIG. 4, the optical output signal output from the light-emitting element 50 of the converter 20 gradually decreases due to deterioration over time. Therefore, when a test pattern that gradually decreases the light output 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 deterioration of the light-emitting element 50 over time.

The test pattern detector 66 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. The test pattern detector 66 detects deterioration of the light-emitting element 50 provided in the transmitting converter 20 when the reception period of the test pattern falls below 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.

For example, when the test pattern detector 66 detects deterioration of the light-emitting element 50 of one of the multiple converters 20, the first control unit 31 notifies the user of the detected 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 detected deterioration of the light-emitting element 50 of the corresponding converter 20 by displaying the detected deterioration of the light-emitting element 50 of the corresponding converter 20 on the display unit. This allows the user to appropriately notify workers and others of the detected deterioration of the light-emitting element 50 of a specific converter 20.

However, the manner in which the degradation of the light-emitting element 50 is not limited to the above. For example, the degradation of the light-emitting element 50 may be notified by sending information to a mobile device carried by a worker, such as a smartphone or tablet, and displaying the information on the display unit of the mobile device. The degradation of the light-emitting element 50 may be notified in any manner that can appropriately notify a worker, etc. of the degradation of the light-emitting element 50.

The control device 14 may, for example, store information on the detection of deterioration of the light-emitting element 50, and display the detection of deterioration of the light-emitting element 50 on a display unit or the like based on the operation of 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.

Furthermore, 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 specific converter 20 is detected in the operating system of the first control unit 31 and the second control unit 32.

As such, in the power conversion device 10 according to this embodiment, the main circuit unit 12 has a light-emitting element 50 that outputs 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 output of the light-emitting element 50, and the control device 14 detects deterioration of the light-emitting element 50 when the period for which the test pattern is received becomes equal to or shorter than a predetermined time.

As a result, the power conversion device 10 according to this embodiment can reduce the 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 power 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 communications.

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

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 of 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.

As shown in FIG. 5, in this example, the optical transmission circuit 34 of the second control unit 32 further includes a light quantity 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, which is input to the receiving amplifier 64 and the light quantity meter 67.

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 light quantity of the light-emitting element 50 of the converter 20. The light quantity meter 67 measures, for example, the average light quantity of the pulsed optical signal output from the light-emitting element 50 of the converter 20.

The light intensity meter 67 may, for example, measure the peak value of the light intensity of the light-emitting element 50 of the converter 20. However, methods that detect peak values (peak power) require high-speed detection and processing, which may result in increased complexity and cost of the device. As described above, by configuring the device to measure the average light intensity of the light-emitting element 50, it is possible to appropriately measure the light intensity of the light-emitting element 50 while minimizing the device's complexity and cost.

The light quantity meter 67 inspects the light-emitting element 50 installed 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 installed 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 installed in the transmitter converter 20 when the measured light quantity of the light-emitting element 50 falls below a predetermined value.

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.

When in standby mode, the second control unit 32 requests the multiple converters 20 to send signals for measuring light intensity, as shown in FIG. 6. The transmission request for the signal for measuring light intensity output from the optical transmission circuit 34 of the second control unit 32 is input to the second optical transmission circuit 42 of each of the multiple converters 20 via the optical distributor 18. The transmission request for the signal for measuring light intensity includes, 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.

In response to receiving a request to send a light intensity measurement signal to itself, each converter 20 transmits a light intensity measurement signal 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.

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

In the configuration of the power conversion device 10, if 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 used to detect deterioration of the light-emitting element 50 provided on the optical transmission circuit corresponding to the standby control unit of each converter 20.

As such, in this example, the standby control unit, either the first control unit 31 or the second control unit 32, requests the main circuit unit 12 to send a signal for measuring light intensity. The main circuit unit 12 then transmits the signal for measuring light intensity from the light-emitting element 50 of the optical transmission circuit, either the first optical transmission circuit 41 or the second optical transmission circuit 42, that corresponds to the standby control unit. The standby control unit measures the light intensity of the light-emitting element 50 based on the received signal for measuring light intensity.

As a result, in this embodiment, inspection of the light-emitting elements 50 provided on 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 on the optical transmission circuit corresponding to the standby system control unit of each converter 20, it is possible to obtain, for example, deterioration progression data of the light-emitting elements 50, 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 progression data.

Furthermore, as shown in FIG. 6, the second control unit 32 sequentially requests the multiple converters 20 to transmit signals for measuring light intensity, with a time lag. Furthermore, the second control unit 32 continuously transmits a request to transmit a signal for measuring light intensity multiple times to one converter 20 out of the multiple converters 20.

The light intensity meter 67 measures the average light intensity of the light-emitting element 50 of the converter 20, for example, based on a light intensity measurement signal transmitted multiple times in succession from the converter 20. When the average measured light intensity of the light-emitting element 50 falls below a predetermined value, the light intensity meter 67 detects deterioration of the light-emitting element 50 installed in the converter 20 that sent the signal.

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

For example, in the case of 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, as in the first embodiment described above.

The control device 14 may, for example, measure the light intensity of each light-emitting element 50 of the first optical transmission circuit 41 and the second optical transmission circuit 42 of each converter 20 by switching between the operating system and 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 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 standby system may be any timing at which switching is possible.

Furthermore, when switching between the operating system and 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 a test pattern detector 66. In other words, it is possible to only measure the light intensity of the light-emitting element 50 in the standby system.

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 may be embodied in a variety of other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their variations are within the scope and spirit of the invention, as well as the scope of the invention and its equivalents as set forth in the claims. Furthermore, the above-described embodiments may be implemented in combination with each other.

DESCRIPTION OF SYMBOLS 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...transmission 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...transmission buffer, 63...light-receiving element, 64...receiving amplifier, 65...receiving buffer, 66...test pattern detector, 67...light amount meter

Claims (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, 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. 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. The power conversion device described in claim 2, wherein the control device measures the light intensity of the light-emitting elements of the first optical transmission circuit and the second optical transmission circuit by switching between the operating system and standby system of the first control unit and the second control unit at a predetermined timing. 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. 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.