Power Conversion Device

Abstract

To provide a power conversion device that can save labor in inspection work.SOLUTION: A power conversion device includes a main circuit portion that performs power conversion, and a monitoring device that acquires information regarding the health of the main circuit portion and enables checking temporal changes in the health of the main circuit portion.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 are power conversion devices that convert electric power. Power conversion devices are required to have a long lifespan. In particular, power conversion devices used in highly public facilities, such as power conversion devices connected to power grids, are required to operate stably for a long period of time and to minimize unintended operational shutdowns due to failures, etc. For this reason, power conversion devices are inspected periodically to check their soundness, and partial parts are replaced as necessary.

[0003] Checking the soundness of a power conversion device requires inspection by personnel. However, a power conversion device is composed of many components, such as semiconductor devices and capacitors. In addition, depending on the type of soundness to be checked, inspection work may need to be performed by connecting an external device to the power conversion device. For this reason, inspecting a power conversion device requires a large number of labor hours, a long time, and high costs. Furthermore, inspecting a power conversion device requires stopping the operation of the power conversion device, which affects the operation of the power conversion device.

[0004] For example, it has been proposed to detect component anomalies based on whether a predetermined threshold is exceeded. In this case, component anomalies can be detected without the need for an operator to inspect the components. However, this type of anomaly detection does not allow for the understanding of trends in component changes over time, and an anomaly is suddenly detected when a threshold is exceeded. Therefore, for example, if it is difficult to stop a power conversion device at an arbitrary timing and periodic inspections are performed at set intervals, it may be necessary to inspect the health of components in areas where no anomalies have been detected to prevent anomalies from occurring before the next inspection. As such, detecting anomalies by setting a predetermined threshold may not necessarily lead to labor savings in inspection work.

[0005] For this reason, it is desirable to reduce the labor required for inspection of power conversion devices, thereby shortening the inspection work time and reducing the costs required for the inspection work. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-254017 Summary of the Invention [Problem to be solved by the invention]

[0007] The embodiments of the present invention provide a power conversion device that can reduce the labor required for inspection work. [Means for solving the problem]

[0008] According to an embodiment of the present invention, a plurality of switching elements and a plurality of drive circuits for switching the plurality of switching elements, A main circuit section that converts power and information on the soundness of the main circuit section of acquisition death, The change in the health of the main circuit section over time Monitor A monitoring device; a control device for controlling the operation of the main circuit unit; Equipped with The control device generates a plurality of control signals corresponding to each of the plurality of switching elements, inputs the generated control signals to the main circuit unit, and controls the switching of each of the plurality of switching elements, thereby controlling the power conversion by the main circuit unit; the plurality of drive circuits generate a plurality of drive signals according to the plurality of control signals, and inputs the plurality of drive signals to the corresponding plurality of switching elements, thereby driving the plurality of switching elements according to the plurality of control signals, and detects the plurality of drive signals and inputs a plurality of feedback signals according to the detected plurality of drive signals to the control device; the monitoring device acquires information on the plurality of control signals and information on the plurality of feedback signals, and based on the information on the plurality of control signals and the information on the plurality of feedback signals, stores delay times of the feedback signals relative to the control signals and whether or not the feedback signals have been lost as information indicating the health of the plurality of drive circuits. A power converter is provided. [Effects of the Invention]

[0009] A power conversion device that can reduce inspection work is provided. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a block diagram schematically illustrating a power conversion device according to a first embodiment. [Figure 2] FIG. 10 is a block diagram schematically illustrating a power conversion device according to a second embodiment. [Figure 3] FIG. 10 is a block diagram schematically illustrating an example of a drive circuit according to a second embodiment. [Figure 4] FIG. 10 is a waveform diagram schematically illustrating an example of the operation of the control device according to the second embodiment. [Figure 5] FIG. 10 is a block diagram schematically illustrating a power conversion device according to a third embodiment. [Figure 6] FIG. 10 is a block diagram schematically illustrating a power conversion device according to a fourth embodiment. [Figure 7] FIG. 10 is a block diagram schematically illustrating a power conversion device according to a fifth embodiment. [Figure 8] FIG. 10 is a block diagram schematically illustrating a power conversion device according to a sixth embodiment. [Figure 9] FIG. 13 is a block diagram schematically illustrating a power conversion device according to a seventh embodiment. [Figure 10] FIG. 13 is a block diagram schematically illustrating a power conversion device according to an eighth embodiment.

[0011] Each embodiment will be described below with reference to the drawings. The drawings are schematic or conceptual, and the relationship between the thickness and width of each part, the size ratio between 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 designated by the same reference numerals, and detailed descriptions thereof will be omitted as appropriate.

[0012] (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 monitoring device 14.

[0013] The main circuit unit 12 converts power. The main circuit unit 12 has a first converter 21, a second converter 22, a charge storage element 23, and a voltage detector 24. The first converter 21 is connected to the second converter 22 and the AC power system 2. The first converter 21 converts AC power supplied from the power system 2 into DC power and outputs the converted DC power to the second converter 22. In other words, the first converter 21 is a rectifier.

[0014] The second converter 22 is connected to the first converter 21 and the AC load 4. The second converter 22 converts the DC power output from the first converter 21 into AC power according to the load 4 and outputs the converted AC power to the load 4. The second converter 22 converts, for example, the DC power into AC power different from the AC power of the power grid 2. In other words, the second converter 22 is an inverter.

[0015] The charge storage element 23 is provided on the DC side of each of the first converter 21 and the second converter 22. In other words, the charge storage element 23 is provided between the first converter 21 and the second converter 22. The charge storage element 23 suppresses fluctuations in the DC voltages of the first converter 21 and the second converter 22, for example. The charge storage element 23 is, for example, a DC capacitor.

[0016] In this way, the main circuit unit 12 converts the AC power of the power system 2 into another AC power corresponding to the load 4, and supplies the converted AC power to the load 4. The load 4 may be an AC load such as an induction machine, or may be a power system separate from the power system 2.

[0017] The main circuit unit 12 may further have a function of, for example, converting AC power on the load 4 side and outputting it to the power grid 2. The second converter 22 may have a function of converting AC power on the load 4 side into DC power and outputting it to the first converter 21. The first converter 21 may have a function of converting DC power into AC power according to the power grid 2 and outputting it to the power grid 2.

[0018] The first converter 21 and the second converter 22 each have, for example, a plurality of bridge-connected switching elements (semiconductor elements) and a plurality of rectifier elements connected in anti-parallel to each of the plurality of switching elements. The power conversion device 10 (main circuit unit 12) is, for example, a semiconductor power conversion device.

[0019] The voltage detector 24 detects the DC voltage value of the charge storage element 23. The voltage detector 24 inputs information on the detected DC voltage value of the charge storage element 23 to the monitoring device 14.

[0020] The monitoring device 14 acquires information about the health of the main circuit section 12, and is able to confirm changes over time in the health of the main circuit section 12. In this example, the monitoring device 14 acquires information about the DC voltage value of the charge storage element 23 detected by the voltage detector 24 as information about the health of the main circuit section 12, and is able to confirm changes over time in the health of the charge storage element 23 as changes over time in the health of the main circuit section 12 based on the information about the DC voltage value.

[0021] As deterioration of the charge storage element 23 progresses, the capacitance decreases and the voltage ripple and noise components superimposed on the DC voltage of the charge storage element 23 increase. The monitoring device 14, for example, performs frequency analysis on the information of the DC voltage value input from the voltage detector 24, and checks the state of the voltage ripple and noise components as the health (deterioration level) of the charge storage element 23.

[0022] The monitoring device 14, for example, checks the soundness of the main circuit unit 12 based on the acquired information and stores the check results of the soundness of the main circuit unit 12. In this example, the monitoring device 14 stores the check results of the soundness of the charge storage element 23. The monitoring device 14 stores, for example, the state of the voltage ripple and noise components as the check results. The state of the voltage ripple and noise components is, for example, the magnitude of the frequency and amplitude of the ripple and noise superimposed on the DC voltage of the charge storage element 23.

[0023] However, the information stored as the confirmation result is not limited to this, and may be any information that can confirm the health of the charge storage element 23. For example, if the magnitude of the capacitance of the charge storage element 23 can be estimated from the state of the voltage ripple, etc., the estimated value of the capacitance of the charge storage element 23 may be stored as the confirmation result. For example, the degree of deterioration of the charge storage element 23 may be calculated from the state of the voltage ripple or noise component, and the calculated degree of deterioration may be stored as the confirmation result. For example, the degree of deterioration of the charge storage element 23 may be expressed as a numerical value such as 0% to 100%, or may be expressed in stages such as 1 to 5 levels.

[0024] The monitoring device 14, for example, periodically or continuously checks the soundness of the main circuit unit 12 and stores the check result each time it checks. As a result, the monitoring device 14 stores multiple check results acquired over time.

[0025] In other words, the monitoring device 14 monitors the health of the main circuit section 12 (charge storage element 23). The monitoring device 14 may constantly monitor the health of the main circuit section 12, or may monitor it as needed at a predetermined timing. The voltage detector 24 may constantly acquire information about the health of the main circuit section 12 and input the acquired information to the monitoring device 14, or may do so as needed at a predetermined timing.

[0026] The monitoring device 14 stores multiple confirmation results acquired over time, thereby enabling the monitoring device 14 to check changes in the confirmation results over time. This allows the monitoring device 14 to check changes in the health of the main circuit unit 12 over time.

[0027] The monitoring device 14 has, for example, a calculation unit that checks the soundness of the main circuit unit 12 based on input information, a memory unit that stores the check results, and an output unit that outputs the check results stored in the memory unit.

[0028] The output unit is, for example, a display unit such as a liquid crystal display. This allows, for example, a worker inspecting the power conversion device 10 to check the change over time in the health of the main circuit unit 12 by referring to the confirmation results displayed on the display unit. In this case, the monitoring device 14 may further include, for example, an operation unit for receiving input of operation instructions from a worker or the like, and may display the change over time in the health of the main circuit unit 12 on the display unit in response to the input of operation instructions from the operation unit. The operation unit may be, for example, a well-known input device such as a mouse or a keyboard.

[0029] The output unit may be, for example, a communication unit for communicating with an external device. The monitoring device 14 may output the temporal change in the health of the main circuit unit 12 to, for example, a stationary terminal installed in a room where an operator or the like is present or a portable terminal owned by an operator or the like, so that the temporal change in the health of the main circuit unit 12 can be referenced by the external device. In this case, the monitoring device 14 may communicate with the external device via the communication unit and output the temporal change in the health of the main circuit unit 12 to the external device in response to a request from the external device.

[0030] However, the method by which the monitoring device 14 can check the changes in the health of the main circuit section 12 over time is not limited to the above, and any method that allows workers or others to appropriately check the changes in the confirmation results over time can be used.

[0031] As described above, in the power conversion device 10 according to this embodiment, the monitoring device 14 acquires information regarding the health of the main circuit unit 12, enabling changes in the health of the main circuit unit 12 over time to be confirmed. As a result, in the power conversion device 10 according to this embodiment, a worker or the like who inspects the power conversion device 10 need only inspect the main circuit unit 12 when, for example, a change in the health of the main circuit unit 12 is detected, and the inspection can be omitted if no change in the health of the main circuit unit 12 is detected. In this example, the degree of deterioration of the charge storage element 23 can be easily grasped, and the inspection of the health of the charge storage element 23 can be omitted. The effort of inspecting the charge storage element 23 and checking the degree of deterioration of the charge storage element 23 can be omitted.

[0032] Therefore, with the power conversion device 10 according to this embodiment, it is possible to narrow down the items to be inspected, thereby reducing the labor required for the inspection work. For example, it is possible to shorten the inspection work time and reduce the costs required for the inspection work. Furthermore, by shortening the inspection work time, it is possible to shorten the period during which the operation of the power conversion device 10 is stopped due to the inspection work, thereby suppressing the impact on the operation of the power conversion device 10.

[0033] In this example, the monitoring device 14 acquires information about the DC voltage value of the charge storage element 23 detected by the voltage detector 24 as information about the health of the main circuit unit 12. The voltage detector 24 may be provided in the power conversion device 10 for controlling the first converter 21 and the second converter 22. In this case, the health of the charge storage element 23 can be confirmed without adding a sensor, etc. For example, when checking the health of the main circuit unit 12, an increase in the number of parts can be suppressed.

[0034] When checking the soundness of the charge storage element 23, the configuration of the main circuit unit 12 is not necessarily limited to the above. The main circuit unit 12 is not limited to a configuration having two converters, the first converter 21 and the second converter 22, and may be a configuration having a single converter. The main circuit unit 12 may be configured in any way as long as it has at least a converter that converts at least one of AC power to DC power and DC power to AC power, a charge storage element provided on the DC side of the converter, and a voltage detector that detects the DC voltage value of the charge storage element.

[0035] (Second embodiment) FIG. 2 is a block diagram schematically illustrating a power conversion device according to the second embodiment. As shown in FIG. 2, the power conversion device 30 includes a main circuit section 32, a monitoring device , and further includes a control device .

[0036] The main circuit unit 32 converts electric power. The main circuit unit 32 has a plurality of switching elements 40. In other words, the plurality of switching elements 40 are semiconductor elements. The main circuit unit 32 converts electric power by switching the plurality of switching elements 40.

[0037] The main circuit unit 32 includes, for example, six switching elements 40 connected in a three-phase bridge configuration, six rectifier elements 42 connected in anti-parallel to each of the six switching elements 40, and charge storage elements 44 connected in parallel to each of the six switching elements 40. The main circuit unit 32 performs at least one of conversion from three-phase AC power to DC power and conversion from DC power to three-phase AC power by switching each of the switching elements 40. The main circuit unit 32 is, for example, a three-phase bridge converter.

[0038] However, the configuration of the main circuit unit 32 is not limited to a three-phase bridge converter. The main circuit unit 32 may have any configuration that has a plurality of switching elements 40 and converts power by switching the plurality of switching elements 40. The main circuit unit 32 may be, for example, a single-phase bridge converter or a multilevel inverter such as a three-level inverter. The power conversion by the main circuit unit 32 is not limited to the above and may be any conversion, such as conversion from single-phase AC power to DC power.

[0039] The control device 36 controls the operation of the main circuit unit 32. The control device 36 generates a plurality of control signals corresponding to the plurality of switching elements 40, inputs the generated control signals to the main circuit unit 32, and controls the switching of each of the plurality of switching elements 40, thereby controlling the power conversion by the main circuit unit 32.

[0040] The main circuit unit 32 further has a plurality of drive circuits 46 for driving the respective switching elements 40. The main circuit unit 32 inputs a plurality of control signals input from the control device 36 to the corresponding drive circuits 46. The drive circuits 46 drive the switching of the corresponding switching elements 40 based on the input control signals.

[0041] The multiple switching elements 40 each have, for example, a pair of main terminals and a control terminal, and have an ON state in which current flows between the pair of main terminals, and an OFF state in which current flow between the pair of main terminals is blocked. Note that the OFF state is not limited to a state in which current flow between the pair of main terminals is completely stopped, but may also be a state in which a weak current flows within a range that does not affect the operation of the main circuit unit 32. In other words, the OFF state is a state in which the magnitude of the current flowing between the pair of main terminals is lower than in the ON state. The multiple switching elements 40 switch between the ON state and the OFF state depending on the magnitude of the voltage applied between the pair of main terminals and the magnitude of the voltage applied to the control terminal. Note that the multiple switching elements 40 may be self-excited switching elements or externally excited switching elements.

[0042] Each of the plurality of drive circuits 46 is connected to a control terminal of each of the plurality of switching elements 40, and drives the switching of the corresponding switching element 40 by changing the magnitude of the voltage (the magnitude of the drive signal) applied to the control terminal in response to a control signal input from the control device 36. In other words, the plurality of drive circuits 46 switches the switching element 40 between an on state and an off state by changing the magnitude of the voltage applied to the control terminal.

[0043] FIG. 3 is a block diagram schematically illustrating an example of a drive circuit according to the second embodiment. As shown in FIG. 3, the drive circuit 46 includes, for example, a light receiving element 50, a drive signal generation unit 52, a drive signal detector 54, and a light emitting element 56.

[0044] The drive circuit 46 is connected to the control device 36 via a control signal line. The control signal line is, for example, an optical signal line such as an optical fiber. Communication between the control device 36 and the drive circuit 46 is, for example, optical communication. The control device 36 inputs, for example, an optical signal control signal to the drive circuit 46.

[0045] The light-receiving element 50 receives the optical control signal input from the control device 36, converts it into an electrical signal, and inputs it to the drive signal generation unit 52. The drive signal generation unit 52 generates a drive signal according to the control signal of the electrical signal input from the light-receiving element 50, and inputs it to a control terminal of the switching element 40, thereby driving the switching element 40 according to the control signal.

[0046] The drive signal detector 54 detects the drive signal input from the drive signal generator 52 to the control terminal of the switching element 40, and inputs the detection signal to the light-emitting element 56. The light-emitting element 56 switches between emitting and extinguishing light in accordance with the detection signal input from the drive signal detector 54, and inputs an optical feedback signal to the control device 36.

[0047] In this way, the multiple drive circuits 46 generate multiple drive signals in response to the multiple control signals, and input the multiple drive signals to the corresponding multiple switching elements 40, thereby driving the multiple switching elements 40 in response to the multiple control signals, and also detect the multiple drive signals and input multiple feedback signals in response to the detected multiple drive signals to the control device 36.

[0048] The control device 36 has, for example, a light emitting unit for inputting an optical signal control signal to the drive circuit 46, and a light receiving unit for receiving the optical signal feedback signal input from the drive circuit 46 and converting it into an electrical signal.

[0049] The control device 36 detects abnormalities in the switching element 40 and the drive circuit 46 based on the feedback signal input from the drive circuit 46. When the feedback signal does not respond correctly to the control signal input to the drive circuit 46, the control device 36 detects that an abnormality has occurred in at least one of the switching element 40 and the drive circuit 46.

[0050] FIG. 4 is a waveform diagram schematically illustrating an example of the operation of the control device according to the second embodiment. 4, when the switching element 40 and the drive circuit 46 are normal, the feedback signal has a predetermined delay time relative to the control signal and has substantially the same waveform. On the other hand, when there is an abnormality, such as deterioration, in the components of the switching element 40 and the drive circuit 46, the delay time of the feedback signal relative to the control signal increases, or the pulse itself disappears.

[0051] In this way, when an increase in the delay time or a loss of pulse occurs, the control device 36 detects an abnormality in at least one of the switching element 40 and the drive circuit 46. For example, when the delay time becomes equal to or exceeds a predetermined threshold value or when a loss of pulse occurs, the control device 36 detects an abnormality in at least one of the switching element 40 and the drive circuit 46.

[0052] When an abnormality is detected, the control device 36, for example, notifies the detection of the abnormality. The notification of the detected abnormality may be made by the control device 36 by displaying it on a display unit, or may be made by an external device such as a higher-level controller by outputting the detection of the abnormality to the external device. Furthermore, when an abnormality is detected, the control device 36 may, for example, stop the operation of the main circuit unit 32.

[0053] The monitoring device 34 acquires information on a plurality of control signals and information on a plurality of feedback signals as information on the health of the main circuit unit 32. The monitoring device 34 checks the health of the plurality of drive circuits 46, for example, based on the information on the plurality of control signals and the information on the plurality of feedback signals.

[0054] The monitoring device 34 is, for example, connected to the control device 36, and acquires the feedback signal converted into an electrical signal by the control device 36 as feedback signal information, and also acquires information on the control signal of the electrical signal input from the control device 36 to the drive circuit 46.

[0055] The monitoring device 34 stores the results of checking the health of the multiple drive circuits 46. For example, the monitoring device 34 stores the delay time of the feedback signal relative to the control signal and whether or not a pulse included in the control signal has been lost as the check result. However, the information stored as the check result is not limited to this, and any information that can be used to check the health of the multiple drive circuits 46 may be used.

[0056] As in the first embodiment, the monitoring device 34 periodically or continuously checks the health of the main circuit unit 32, for example, and stores the check results each time it checks. As a result, the monitoring device 34 stores multiple check results acquired over time. By storing multiple check results acquired over time, the monitoring device 34 can check changes over time in the health of the multiple drive circuits 46 as changes over time in the health of the main circuit unit 32. As in the first embodiment, any method can be used to check changes over time in the health of the multiple drive circuits 46.

[0057] In this way, in the power conversion device 30 of this embodiment, even if no abnormality is detected by the control device 36, the degree of deterioration of the multiple drive circuits 46 can be easily grasped by checking the changes over time in the health of the multiple drive circuits 46 using the monitoring device 34.

[0058] For example, the delay time of the feedback signal relative to the control signal increases due to a decrease in the amount of light received by the light receiving element 50 or a decrease in the amount of light emitted by the light emitting element 56. Therefore, by checking the temporal changes in the health of the multiple drive circuits 46 using the monitoring device 34, it is possible to grasp the degree of deterioration of the light receiving element 50, the light emitting element 56, etc.

[0059] As a result, in the power conversion device 30 according to this embodiment, it is possible to omit inspection of the health of the multiple drive circuits 46. This eliminates the need to inspect each drive circuit 46 and check the degree of deterioration of the light receiving element 50, the light emitting element 56, etc. Therefore, similar to the first embodiment, it is possible to reduce the labor required for inspection.

[0060] In this example, the monitoring device 34 acquires information on a plurality of control signals and information on a plurality of feedback signals as information regarding the health of the main circuit unit 32. For example, the plurality of feedback signals may be input from each drive circuit 46 to the control device 36 in order to detect an abnormality in the control device 36. In this case, the health of the plurality of drive circuits 46 can be confirmed without adding sensors, etc. For example, when confirming the health of the main circuit unit 32, an increase in the number of parts can be suppressed.

[0061] The monitoring device 34 is not limited to a configuration in which it receives the control signal and feedback signal as electrical signals from the control device 36. For example, the monitoring device 34 may receive the control signal and feedback signal as optical signals by splitting them from a signal line using a beam splitter, and convert them into electrical signals inside the monitoring device 34. The information on the multiple control signals and the information on the multiple feedback signals may be any information representing these. Furthermore, communication between the control device 36 and each drive circuit 46 is not limited to optical communication, and may be communication using electrical signals, for example.

[0062] (Third embodiment) FIG. 5 is a block diagram schematically illustrating a power conversion device according to the third embodiment. As shown in FIG. 5, the power conversion device 60 includes a main circuit unit 62, a monitoring device 64, and a control device 66.

[0063] The main circuit unit 62 converts power. The main circuit unit 62 has a plurality of converters 71, 72. The plurality of converters 71, 72 convert DC power to AC power or AC power to DC power, and the AC sides of the converters 71, 72 are connected in parallel. The plurality of converters 71, 72 are each connected to an AC load 4, for example. In this example, the DC sides of the plurality of converters 71, 72 are also connected in parallel.

[0064] The main circuit unit 62 further includes a converter 73, a charge storage element 74, and a plurality of current detectors 75 and 76. The converter 73 is connected to each of the converters 71 and 72 and the AC power system 2. The converter 73 converts AC power supplied from the power system 2 into DC power and outputs the converted DC power to the converters 71 and 72.

[0065] The charge storage element 74 is provided on the DC side of the converters 71 and 72 and on the DC side of the converter 73. In other words, the charge storage element 74 is provided between each of the converters 71 and 72 and the converter 73. The charge storage element 74 suppresses fluctuations in the DC voltages of the converters 71 and 72 and the converter 73, for example.

[0066] The plurality of current detectors 75, 76 are provided on the AC side of each of the plurality of converters 71, 72, and detect the AC current values ​​of each of the plurality of converters 71, 72. The current detectors 75, 76 input information on the detected AC current values ​​of each of the plurality of converters 71, 72 to the monitoring device 64 and the control device 66.

[0067] The control device 66 controls the operation of the main circuit unit 62. The control device 66 controls the power conversion by each of the converters 71, 72, and 73. The control device 66 controls the operation of each of the converters 71, 72, and 73 based on information on the AC current values ​​of each of the multiple converters 71 and 72 input from the current detectors 75 and 76.

[0068] The control device 66 detects an abnormality in each of the converters 71, 72, for example, based on information on the AC current values ​​input from the current detectors 75, 76. The control device 66 calculates the current balance of the AC currents detected by the current detectors 75, 76, for example, and detects an abnormality in each of the converters 71, 72 when the calculated current balance exceeds a threshold value (for example, ±10%). The current balance of the AC currents detected by the current detectors 75, 76 is, in other words, a deviation in the amplitude of the AC currents detected by the current detectors 75, 76.

[0069] When the control device 66 detects an abnormality in each of the converters 71, 72, it stops the operation of the main circuit unit 62. In other words, when the control device 66 detects an abnormality in each of the converters 71, 72, it stops the power conversion by each of the converters 71, 72, 73. Note that when the control device 66 detects an abnormality in each of the converters 71, 72, it is not limited to stopping the main circuit unit 62, and may also, for example, notify the user of the detection of the abnormality.

[0070] The monitoring device 64 acquires information on the AC current values ​​detected by the multiple current detectors 75, 76 as information on the health of the main circuit unit 62. The monitoring device 64 checks the health of the multiple converters 71, 72, for example, based on the information on the AC current values ​​detected by the multiple current detectors 75, 76.

[0071] The monitoring device 64 stores the confirmation results of the health of the multiple converters 71, 72. The monitoring device 64 stores, for example, the current balance of the AC current detected by the current detectors 75, 76 as the confirmation result. The monitoring device 64 stores, for example, the deviation in the amplitude of the AC current detected by the current detectors 75, 76 as the confirmation result. For example, if the AC side of each converter 71, 72 is connected to a load 4 or the like via a transformer, the phase deviation of the AC current detected by the current detectors 75, 76 may be stored as the confirmation result. In other words, the current balance of the AC current detected by the current detectors 75, 76 may be the deviation in the phase of the AC current. The current balance may be, for example, the deviation in the amplitude and the phase of the AC current. However, the information stored as the confirmation result is not limited to these and may be any information that can be used to confirm the health of the multiple converters 71, 72 based on information about the AC current value.

[0072] As in the above embodiments, the monitoring device 64 periodically or continuously checks the health of the main circuit unit 62, for example, and stores the check result each time it checks. As a result, the monitoring device 64 stores multiple check results acquired over time. By storing multiple check results acquired over time, the monitoring device 64 can check changes over time in the health of the multiple converters 71, 72 as changes over time in the health of the main circuit unit 62. As in the above embodiments, any method can be used to check changes over time in the health of the multiple converters 71, 72.

[0073] In the power conversion device 60 of this embodiment, even if no abnormality is detected by the control device 66, the degree of deterioration of the multiple converters 71, 72 can be easily determined by checking the changes over time in the health of the multiple converters 71, 72 using the monitoring device 64.

[0074] For example, deviations in the amplitude and phase of the AC current detected by the current detectors 75, 76 become large due to abnormalities in the switching elements or drive circuits of the converters 71, 72, or in the current detectors 75, 76. In other words, these factors may cause the current balance in the converters 71, 72 to be disrupted. For this reason, by checking the changes over time in the health of the multiple converters 71, 72 using the monitoring device 64, it is possible to grasp the degree of deterioration of the switching elements and drive circuits of the converters 71, 72, the current detectors 75, 76, etc.

[0075] As a result, in the power conversion device 60 according to this embodiment, it is possible to omit inspection of the health of the multiple converters 71, 72. When no abnormality is detected by the control device 66, it is possible to save the effort of inspecting each of the converters 71, 72 and each of the current detectors 75, 76 and checking their degree of deterioration. Therefore, as in the above-described embodiments, it is possible to reduce the labor required for inspection.

[0076] In this example, the monitoring device 64 acquires information on AC current values ​​detected by the multiple current detectors 75, 76 as information on the health of the main circuit unit 62. The multiple current detectors 75, 76 may be provided, for example, to detect abnormalities in the converters 71, 72. In this case, the health of the multiple converters 71, 72 can be confirmed without adding sensors, etc. For example, when checking the health of the main circuit unit 62, an increase in the number of parts can be suppressed.

[0077] Note that when the monitoring device 64 acquires information on AC current values ​​detected by the multiple current detectors 75, 76 as information on the health of the main circuit unit 62, the configuration of the main circuit unit 62 is not limited to the above. For example, the DC sides of the multiple converters 71, 72 may be connected in series, or may be individually connected to DC loads, charge storage elements, etc. The main circuit unit 62 may have any configuration that includes at least multiple converters whose AC sides are connected in parallel, and multiple current detectors that detect the AC current values ​​of each of the multiple converters.

[0078] Also, in this example, the monitoring device 64 acquires information on AC current values ​​from the multiple current detectors 75, 76. The monitoring device 64 may acquire information on AC current values ​​detected by the current detectors 75, 76 from, for example, the control device 66. The monitoring device 64 is not limited to a configuration in which it acquires information on AC current values ​​directly from the multiple current detectors 75, 76, but may also be configured to acquire information on AC current values ​​via another device or the like.

[0079] (Fourth embodiment) FIG. 6 is a block diagram schematically illustrating a power conversion device according to the fourth embodiment. 6, the power conversion device 80 includes a main circuit unit 82, a monitoring device 84, and a control device 86. Note that the configurations of the main circuit unit 82 and the control device 86 can be similar to the configurations of the main circuit unit 32 and the control device 36 described with reference to FIG. 2, and therefore detailed description thereof will be omitted.

[0080] The monitoring device 84 acquires information about the voltage values ​​of the control terminals of each of the multiple switching elements 40 as information about the health of the main circuit unit 82. In other words, the monitoring device 84 acquires information about the voltage values ​​of multiple drive signals input from the multiple drive circuits 46 to the multiple switching elements 40 as information about the health of the main circuit unit 82. Based on the acquired information about the voltage values ​​of the control terminals of each of the multiple switching elements 40, the monitoring device 84 is able to confirm changes over time in the health of the multiple switching elements 40 and the multiple drive circuits 46 as changes over time in the health of the main circuit unit 82.

[0081] The monitoring device 84, for example, is connected to the control terminals of the multiple switching elements 40, thereby acquiring information about the voltage values ​​of the control terminals of the multiple switching elements 40. For example, the main circuit unit 82 may be provided with multiple voltage detectors that detect the voltages of the control terminals of the multiple switching elements 40, and the monitoring device 84 may acquire information about the voltage values ​​of the control terminals of the multiple switching elements 40 from the multiple voltage detectors. The method by which the monitoring device 84 acquires information about the voltage values ​​of the control terminals of the multiple switching elements 40 may be any method that can appropriately acquire information about the voltage values ​​of the control terminals.

[0082] The monitoring device 84 stores, for example, information on the acquired voltage values ​​of the control terminals of each of the multiple switching elements 40. The voltages of the control terminals of the switching elements 40 change due to deterioration of the switching elements 40 and the drive circuits 46. Therefore, by checking the temporal changes in the voltages of the control terminals of the switching elements 40, it is possible to check the temporal changes in the health of the multiple switching elements 40 and the multiple drive circuits 46.

[0083] In this way, the monitoring device 84 may store information regarding the health of multiple main circuit sections 82 acquired over time, thereby enabling the monitoring device 84 to check changes in the health of the main circuit sections 82 over time.

[0084] However, the information stored in the monitoring device 84 is not limited to this. For example, the health of the multiple switching elements 40 and multiple drive circuits 46 may be confirmed based on the acquired information, and the confirmation results may be stored. For example, the monitoring device 84 may store the deviation between the acquired control terminal voltage value and a reference value for the control terminal voltage value as the confirmation result. The information stored in the monitoring device 84 is not limited to this, and may be any information that can be used to confirm the health of the multiple switching elements 40 and multiple drive circuits 46.

[0085] In the power conversion device 80 according to this embodiment, the monitoring device 84 checks the changes over time in the health of the multiple switching elements 40 and the multiple drive circuits 46, making it possible to easily grasp the degree of deterioration of the multiple switching elements 40 and the multiple drive circuits 46.

[0086] As a result, in the power conversion device 80 according to this embodiment, it is possible to omit inspection of the health of the multiple switching elements 40 and the multiple drive circuits 46. This eliminates the need to inspect the multiple switching elements 40 and the multiple drive circuits 46 and check their deterioration. For example, it is possible to omit the inspection work of the multiple switching elements 40 and the multiple drive circuits 46 that was previously performed by an operator connecting external devices. Therefore, similar to the above embodiments, it is possible to reduce the labor required for the inspection work.

[0087] (Fifth embodiment) FIG. 7 is a block diagram schematically illustrating a power conversion device according to the fifth embodiment. As shown in Fig. 7, the power conversion device 90 includes a main circuit unit 92, a monitoring device 94, and an imaging device 96. The configuration of the main circuit unit 92 can be similar to the configuration of the main circuit unit 12 described with reference to Fig. 1, and therefore a detailed description thereof will be omitted. The main circuit unit 92 may be configured in any way that converts power.

[0088] The camera 96 ​​photographs the exterior of the main circuit unit 92 and acquires the photographed image of the exterior of the main circuit unit 92. The camera 96 ​​inputs the acquired photographed image to the monitoring device 94. The camera 96 ​​is, for example, a fixed-point camera installed around the main circuit unit 92. The camera 96 ​​may be, for example, a mobile object such as a drone that photographs the exterior of the main circuit unit 92 while moving around the main circuit unit 92. The camera 96 ​​may be configured in any way that is capable of photographing the exterior of the main circuit unit 92. The power conversion device 90 may be configured, for example, to include multiple camera devices 96, and input multiple photographed images taken by each of the multiple camera devices 96 to the monitoring device 94. The photographed images input from the camera 96 ​​to the monitoring device 94 may be still images or moving images.

[0089] The monitoring device 94 acquires information about the captured images acquired by the imaging device 96 as information about the health of the main circuit section 92. Based on the acquired information about the captured images, the monitoring device 94 is able to confirm temporal changes in the appearance of the main circuit section 92 as temporal changes in the health of the main circuit section 92.

[0090] The monitoring device 94 checks the external soundness of the main circuit unit 92, for example, based on information from captured images. When used over a long period of time, the components used in the main circuit unit 92 may develop cracks due to thermal fatigue, or rust or discoloration due to the influence of the surrounding environment. Accumulated dust may also lead to abnormalities in the device. The monitoring device 94 checks the external soundness of the main circuit unit 92, for example, by performing image processing on the information from the captured images to determine whether or not there are any abnormalities in the external appearance of the main circuit unit 92, such as cracks, rust, discoloration, or dust, and the extent of the abnormalities.

[0091] The monitoring device 94 stores the results of the confirmation of the external soundness of the main circuit unit 92. The monitoring device 94 stores, for example, the results of image processing of the captured image as the confirmation result. The results of the image processing may, for example, be stored as text information indicating the presence or absence of an abnormality, or may be stored as a scale indicating the degree of the abnormality. The results of the image processing may, for example, include information on the location where a sign of an abnormality appears, if such a sign appears. However, the information stored as the confirmation result is not limited to this, and may be any information that can be used to confirm the external soundness of the main circuit unit 92 based on the information of the captured image.

[0092] As in the above-described embodiments, the monitoring device 94 periodically or continuously checks the external appearance of the main circuit unit 92, and stores the check results each time it checks. As a result, the monitoring device 94 stores multiple check results acquired over time. By storing multiple check results acquired over time, the monitoring device 94 makes it possible to check changes over time in the external appearance of the main circuit unit 92. As in the above-described embodiments, any method may be used to check changes over time in the external appearance of the main circuit unit 92.

[0093] The monitoring device 94 may store information about the photographed image captured by the photographing device 96, as well as store a plurality of photographed images captured over time, and display the plurality of photographed images side by side, thereby enabling the monitoring device 94 to check changes over time in the appearance of the main circuit unit 92. The monitoring device 94 does not necessarily have to perform image processing, etc.

[0094] In the power conversion device 90 according to this embodiment, the change in the appearance of the main circuit section 92 over time can be checked using the monitoring device 94, making it easy to grasp the degree of deterioration in the appearance of the main circuit section 92.

[0095] As a result, in the power conversion device 90 according to this embodiment, inspection of the appearance of the main circuit unit 92 can be omitted. For example, it is possible to eliminate the need for an operator to visually check each and every component used in the main circuit unit 92 for cracks, discoloration, or the like. Therefore, as with the above-described embodiments, it is possible to reduce the labor required for inspection. Furthermore, for example, if signs of dust accumulation or the like appear, it is only necessary to clean the relevant area during inspection, thereby reducing the amount of work required during inspection.

[0096] (Sixth embodiment) FIG. 8 is a block diagram schematically illustrating a power conversion device according to the sixth embodiment. As shown in Fig. 8, the power conversion device 100 includes a main circuit unit 102, a monitoring device 104, and a temperature detection device 106. The configuration of the main circuit unit 102 can be similar to the configuration of the main circuit unit 12 described with reference to Fig. 1, and therefore a detailed description thereof will be omitted. The main circuit unit 102 may have any configuration that converts power.

[0097] The temperature detecting device 106 detects the temperature of the main circuit section 102 and acquires temperature information relating to the temperature of the main circuit section 102. The temperature detecting device 106 inputs the acquired temperature information to the monitoring device 104.

[0098] The temperature detection device 106 is, for example, an infrared thermal imaging device (thermography). The temperature detection device 106 detects, for example, the surface temperature of the main circuit unit 102. The temperature detection device 106 detects, for example, the surface temperatures of multiple components used in the main circuit unit 102. When the temperature detection device 106 is an infrared thermal imaging device, the temperature detection device 106 captures an image of the main circuit unit 102 and acquires, as temperature information, a thermal image whose display mode changes depending on the surface temperature of the main circuit unit 102. The display mode is, for example, the display color or the shade of the color. The display mode may be any mode that allows the temperature to be identified on the image.

[0099] The monitoring device 104 acquires the temperature information acquired by the temperature detection device 106 as information regarding the health of the main circuit section 102. Based on the acquired temperature information, the monitoring device 104 is able to confirm temporal changes in the temperature of the main circuit section 102 as temporal changes in the health of the main circuit section 102.

[0100] For example, if the temperature information is a thermal image, the monitoring device 104 performs image processing on the thermal image to check the temperature of the main circuit unit 102. The monitoring device 104 performs image processing on the thermal image to check the temperatures of multiple locations on the main circuit unit 102. In other words, the monitoring device 104 performs image processing on the thermal image to check the temperatures of multiple components used in the main circuit unit 102.

[0101] The monitoring device 104 stores, for example, the confirmation results of the temperature of the main circuit unit 102. The monitoring device 104, for example, periodically or continuously checks the temperature of the main circuit unit 102 and stores the confirmation result each time it checks. In this way, the monitoring device 104 stores multiple confirmation results acquired over time. By storing multiple confirmation results acquired over time, the monitoring device 104 makes it possible to check changes in the temperature of the main circuit unit 102 over time. As with the above-described embodiments, any method may be used to check changes in the temperature of the main circuit unit 102 over time.

[0102] The monitoring device 104 may store, for example, the thermal image acquired by the temperature detection device 106, as well as a plurality of thermal images acquired over time, and display the plurality of thermal images side by side, thereby enabling the user to check the change in temperature of the main circuit unit 102 over time. The monitoring device 104 does not necessarily need to perform image processing, etc.

[0103] A rise in the temperature of the components used in the main circuit unit 102 may lead to component degradation or failure. Furthermore, the temperature of the components used in the main circuit unit 102 may rise in response to component degradation or abnormality. Therefore, in the power conversion device 100 according to this embodiment, the monitoring device 104 is configured to monitor temporal changes in the temperature of the main circuit unit 102. As a result, in the power conversion device 100 according to this embodiment, inspection of the main circuit unit 102 can be omitted, for example, when there is no abnormal temperature rise. For example, when it is possible to monitor temporal changes in the temperatures of multiple components used in the main circuit unit 102, inspection of specific components can be omitted. Then, workers need only inspect the relevant parts when there is an abnormal temperature rise. Therefore, as in the above-described embodiments, labor-saving inspection work can be achieved.

[0104] The temperature detection device 106 is not limited to an infrared thermal imaging device, and may detect the temperature of the main circuit section 102 using a temperature sensor such as a thermocouple. The temperature detection device 106 may detect the temperatures of multiple components used in the main circuit section 102 by using multiple temperature sensors, for example. In this case, the temperature detection device 106 is not limited to detecting the surface temperature of the main circuit section 102, but may also detect the internal temperatures of the components used in the main circuit section 102. The temperature detected by the temperature detection device 106 may be any temperature of the main circuit section 102. The temperature detection device 106 may be configured in any way that can detect the temperature of the main circuit section 102 and acquire temperature information related to the temperature of the main circuit section 102.

[0105] The temperature information may be, for example, a detected value of the temperature of the main circuit unit 102 detected by a temperature sensor. In this case, the monitoring device 104 may store a plurality of pieces of temperature information acquired over time, thereby enabling the monitoring device 104 to check changes in the temperature of the main circuit unit 102 over time. The temperature information may be any information related to the temperature of the main circuit unit 102.

[0106] (Seventh embodiment) FIG. 9 is a block diagram schematically illustrating a power conversion device according to the seventh embodiment. 9, the power conversion device 110 includes a main circuit unit 112, a monitoring device 114, and an abnormal sound detection device 116. The configuration of the main circuit unit 112 can be similar to the configuration of the main circuit unit 12 described with reference to FIG. 1, and therefore a detailed description thereof will be omitted. The main circuit unit 112 may be configured in any manner that converts power.

[0107] The abnormal sound detection device 116 detects abnormal sounds emitted from the main circuit unit 112 and acquires abnormal sound information related to the abnormal sounds emitted from the main circuit unit 112. The abnormal sound detection device 116 inputs the acquired abnormal sound information to the monitoring device 114.

[0108] The abnormal sound detection device 116 includes, for example, a microphone that converts sound into an electrical signal and a signal processing unit that detects abnormal sounds by analyzing the electrical signal output from the microphone. The signal processing unit, for example, analyzes the electrical signal to detect the occurrence of abnormal sounds by analyzing the sound volume and frequency components contained in the sound. The signal processing unit may detect whether abnormal sounds are occurring in the main circuit unit 112, or may be able to identify the component of the main circuit unit 112 that is emitting the abnormal sound. However, the configuration of the abnormal sound detection device 116 is not limited to the above and may be any configuration that can detect abnormal sounds emitted from the main circuit unit 112. The abnormal sound detection device 116 may, for example, include multiple microphones so as to detect the occurrence of abnormal sounds from specific components used in the main circuit unit 112.

[0109] The monitoring device 114 acquires the abnormal sound information acquired by the abnormal sound detection device 116 as information regarding the soundness of the main circuit section 112. Based on the acquired abnormal sound information, the monitoring device 114 is able to confirm temporal changes in the abnormal sound emitted from the main circuit section 112 as temporal changes in the soundness of the main circuit section 112.

[0110] The monitoring device 114 stores, for example, abnormal sound information acquired by the abnormal sound detection device 116. The abnormal sound detection device 116 acquires the abnormal sound information periodically or continuously, for example. The monitoring device 114 stores the acquired abnormal sound information each time the abnormal sound detection device 116 acquires the abnormal sound information. The monitoring device 114 stores multiple pieces of abnormal sound information acquired over time, thereby making it possible to check changes over time in abnormal sounds emitted from the main circuit unit 112. As with the above embodiments, any method may be used to check changes over time in abnormal sounds emitted from the main circuit unit 112.

[0111] Abnormal noise emitted from the main circuit unit 112 may become louder depending on the degree of deterioration of the components used in the main circuit unit 112. Abnormal noise emitted from the main circuit unit 112 may become louder due to, for example, deterioration or abnormality of a cooling fan, a reactor, or the like. For this reason, in the power conversion device 110 according to this embodiment, the monitoring device 114 is configured to check changes over time in abnormal noise emitted from the main circuit unit 112. As a result, in the power conversion device 110 according to this embodiment, for example, inspection of the main circuit unit 112 can be omitted when no abnormal noise is occurring. Then, workers or the like need only inspect the main circuit unit 112 when abnormal noise is occurring. Therefore, as in the above-described embodiments, labor-saving inspection work can be achieved.

[0112] (Eighth embodiment) FIG. 10 is a block diagram schematically illustrating a power conversion device according to the eighth embodiment. 10, the power conversion device 120 includes a main circuit unit 122, a monitoring device 124, and an odor detection device 126. The configuration of the main circuit unit 122 can be similar to the configuration of the main circuit unit 12 described with reference to Fig. 1, and therefore a detailed description thereof will be omitted. The configuration of the main circuit unit 122 may be any configuration that converts power.

[0113] The odor detection device 126 detects odors around the main circuit unit 122 and acquires odor information related to the odors around the main circuit unit 122. The odor detection device 126 inputs the acquired odor information to the monitoring device .

[0114] The odor detection device 126 digitizes the odor intensity of the gas taken in by changing the resistance value or potential difference of the sensor portion according to the components contained in the gas taken in by the sensor portion, and outputs the digitized odor information. However, the configuration of the odor detection device 126 is not limited to the above, and any configuration that can detect odors around the main circuit unit 122 may be used. The odor detection device 126 is not limited to, for example, a device that digitizes and outputs odor intensity, but may also be, for example, a device that outputs the type of odor around the main circuit unit 122 as odor information according to the components contained in the air around the main circuit unit 122. The odor detection device 126 may be, for example, a device that digitizes the odor intensity for each type of odor around the main circuit unit 122 and outputs the odor information.

[0115] The monitoring device 124 acquires the odor information acquired by the odor detection device 126 as information relating to the health of the main circuit unit 122. Based on the acquired odor information, the monitoring device 124 is able to confirm temporal changes in the odor around the main circuit unit 122 as temporal changes in the health of the main circuit unit 122.

[0116] The monitoring device 124 stores, for example, odor information acquired by the odor detection device 126. The monitoring device 124 stores, for example, a numerical value representing the intensity of the odor as odor information. The odor detection device 126 acquires odor information, for example, periodically or continuously. The monitoring device 124 stores the acquired odor information, for example, each time odor information is acquired by the odor detection device 126. The monitoring device 124 stores multiple pieces of odor information acquired over time, thereby enabling the monitoring device 124 to check changes in odors over time around the main circuit unit 122. As with the above embodiments, any method may be used to check changes in odors over time around the main circuit unit 122.

[0117] The odor around the main circuit unit 122 may change depending on the degree of deterioration of the components used in the main circuit unit 122. In the main circuit unit 122, for example, a rise in temperature due to component deterioration may increase the amount of chemical substances released, possibly resulting in a stronger odor. For this reason, in the power conversion device 120 according to this embodiment, the monitoring device 124 is configured to check temporal changes in the odor around the main circuit unit 122. As a result, in the power conversion device 120 according to this embodiment, for example, inspection of the main circuit unit 122 can be omitted when no odor is being generated. Then, workers or the like need only inspect the main circuit unit 122 when an odor is being generated. Therefore, as in the above embodiments, the inspection work can be reduced in labor.

[0118] In a configuration that includes a camera 96, a temperature detector 106, an abnormal sound detector 116, an odor detector 126, and the like, the introduction of these devices may increase initial costs. However, by reducing the labor required for inspection as described above, it is possible to reduce the cost of the workers required for each inspection and the work time, including the travel time to the site. Therefore, even if the initial costs increase, it is possible to reduce the overall life cycle cost, including the cost required for inspections.

[0119] The above-described embodiments can be combined in any manner. For example, by providing the photographing device 96 and the temperature detecting device 106, the monitoring device can acquire photographed image information and temperature information, and check changes in the appearance of the main circuit unit over time and changes in the temperature of the main circuit unit over time. This can, for example, further reduce the labor required for inspection work.

[0120] Furthermore, the information regarding the health of the main circuit section acquired by the monitoring device is not limited to the above, and any information that can confirm changes in the health of the main circuit section over time may be used.

[0121] Although several embodiments of the present invention have been described, 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, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0122] 2...power system, 4...load, 10, 30, 60, 80, 90, 100, 110, 120...power conversion device, 12, 32, 62, 82, 92, 102, 112, 122...main circuit section, 14, 34, 64, 84, 94, 104, 114, 124...monitoring device, 21...first converter, 22...second converter, 23...charge storage element, 24...voltage detector, 36, 66, 86...control device, 40...switching element, 42...rectifier element, 44...charge storage element, 46...drive circuit, 50...light receiving element, 52...drive signal generation section, 54...drive signal detector, 56...light emitting element, 71 to 73...converter, 74...charge storage element, 75, 76...current detector, 96...imaging device, 106...Temperature detection device, 116...Abnormal sound detection device, 126...Odor detection device

Claims

1. A power converter comprising: a main circuit section that converts power and includes a plurality of switching elements and a plurality of drive circuits for switching the plurality of switching elements; a monitoring device that acquires information about the health of the main circuit unit and monitors changes in the health of the main circuit unit over time; a control device for controlling the operation of the main circuit unit; Equipped with the control device generates a plurality of control signals corresponding to the plurality of switching elements, inputs the generated control signals to the main circuit unit, and controls the switching of the plurality of switching elements, thereby controlling the power conversion by the main circuit unit; the plurality of drive circuits generate a plurality of drive signals in response to the plurality of control signals, and input the plurality of drive signals to the corresponding plurality of switching elements, thereby driving the plurality of switching elements in response to the plurality of control signals, and also detect the plurality of drive signals, and input a plurality of feedback signals in response to the detected plurality of drive signals to the control device; The monitoring device acquires information on the plurality of control signals and information on the plurality of feedback signals, and based on the information on the plurality of control signals and the information on the plurality of feedback signals, stores the delay time of the feedback signal relative to the control signal and whether or not the feedback signal has been lost as information indicating the health of the plurality of drive circuits.

2. Each of the plurality of drive circuits a light receiving element that receives the control signal as an optical signal and converts it into an electrical signal; a drive signal generating unit that generates the drive signal in response to the control signal of the electrical signal input from the light receiving element, and inputs the drive signal to the switching element, thereby driving the switching element in response to the control signal; a drive signal detector that detects the drive signal input from the drive signal generator to the switching element and outputs a detection signal; a light-emitting element that switches between emitting and extinguishing light in response to the detection signal output from the drive signal detector, thereby inputting the feedback signal of the optical signal to the control device; The power converter according to claim 1 , further comprising:

3. The power conversion device described in claim 1, wherein the monitoring device stores information indicating the health of the multiple drive circuits as multiple pieces of information arranged in chronological order by acquiring the delay time of the feedback signal relative to the control signal and whether or not the feedback signal has disappeared over time.

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