JP7751961B2 - Power Conversion Device - Google Patents

Description

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

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 those connected to power grids, are required to operate stably over long periods of time and to minimize unintended operational shutdowns due to malfunctions. For this reason, power conversion devices are inspected regularly to check their integrity, and parts are partially replaced as necessary.

Checking the integrity of power conversion equipment requires inspection by personnel. However, power conversion equipment is made up of many components, including semiconductor devices and capacitors. Furthermore, depending on the type of integrity being checked, inspection work may require connecting external equipment to the power conversion equipment. This makes inspecting power conversion equipment a labor-intensive process, requiring a long time and high cost. Furthermore, inspecting a power conversion equipment requires shutting down the equipment, which impacts its operation.

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

For this reason, it is desirable to reduce the labor required for inspection of power conversion devices, shorten the inspection work time, and reduce the costs required for inspection work.

Japanese Patent Application Laid-Open No. 2009-254017

Embodiments of the present invention provide a power conversion device that reduces the labor required for inspection work.

According to an embodiment of the present invention, there is provided a power conversion device comprising: a main circuit section which has a plurality of switching elements and a plurality of drive circuits for switching each of the plurality of switching elements and converts power; a monitoring device which acquires information on the health of the main circuit section and monitors changes in the health of the main circuit section over time; and a control device which controls the operation of the main circuit section , wherein 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 section, and controls the switching of each of the plurality of switching elements, thereby controlling the power conversion by the main circuit section; the plurality of drive circuits generate a plurality of drive signals in response 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 in response to the plurality of control signals, and detects the plurality of drive signals and inputs a plurality of feedback signals in response to the detected plurality of drive signals to the control device; and 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 a 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 .

A power conversion device is provided that reduces the labor required for inspection work.

1 is a block diagram schematically illustrating a power conversion device according to a first embodiment. FIG. 10 is a block diagram schematically illustrating a power conversion device according to a second embodiment. FIG. 10 is a block diagram schematically illustrating an example of a drive circuit according to a second embodiment. FIG. 10 is a waveform diagram schematically illustrating an example of the operation of the control device according to the second embodiment. FIG. 10 is a block diagram schematically illustrating a power conversion device according to a third embodiment. FIG. 10 is a block diagram schematically illustrating a power conversion device according to a fourth embodiment. FIG. 10 is a block diagram schematically illustrating a power conversion device according to a fifth embodiment. FIG. 10 is a block diagram schematically illustrating a power conversion device according to a sixth embodiment. FIG. 13 is a block diagram schematically illustrating a power conversion device according to a seventh embodiment. FIG. 13 is a block diagram schematically illustrating a power conversion device according to an eighth embodiment.

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.

(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 .

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 grid 2. The first converter 21 converts AC power supplied from the power grid 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.

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 appropriate for the load 4, and outputs the converted AC power to the load 4. The second converter 22, for example, converts 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.

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 voltage of the first converter 21 and the second converter 22, for example. The charge storage element 23 is, for example, a DC capacitor.

In this way, the main circuit unit 12 converts the AC power of the power grid 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 grid separate from the power grid 2.

The main circuit unit 12 may further have the 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 the function of converting AC power from the load 4 into DC power and outputting it to the first converter 21. The first converter 21 may have the function of converting DC power into AC power compatible with the power grid 2 and outputting it to the power grid 2.

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 switching elements. The power conversion device 10 (main circuit unit 12) is, for example, a semiconductor power conversion device.

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

The monitoring device 14 acquires information regarding the health of the main circuit section 12, enabling it to check changes in the health of the main circuit section 12 over time. In this example, the monitoring device 14 acquires information regarding the DC voltage value of the charge storage element 23 detected by the voltage detector 24 as information regarding the health of the main circuit section 12, and, based on the DC voltage value information, enables it to check changes in the health of the charge storage element 23 over time as changes in the health of the main circuit section 12 over time.

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 DC voltage value information input from the voltage detector 24 to check the state of the voltage ripple and noise components as the health (degree of deterioration) of the charge storage element 23.

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

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 capacitance of the charge storage element 23 can be estimated from the state of the voltage ripple, 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 components, 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 the deterioration of the charge storage element 23 may be expressed in stages such as 1 to 5.

For example, the monitoring device 14 periodically or continuously checks the health of the main circuit unit 12 and stores the results of each check. As a result, the monitoring device 14 stores multiple check results obtained over time.

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 predetermined times. 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 predetermined times.

The monitoring device 14 stores multiple confirmation results obtained over time, allowing it 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.

The monitoring device 14 has, for example, a calculation unit that checks the integrity 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.

The output unit is, for example, a display unit such as an LCD display. This allows, for example, a worker inspecting the power conversion device 10 to check the changes 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 have, for example, an operation unit for accepting input of operation instructions from a worker, etc., and may display the changes over time in the health of the main circuit unit 12 on the display unit in response to 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 keyboard.

The output unit may be, for example, a communications unit for communicating with an external device. The monitoring device 14 may output the temporal changes in the health of the main circuit unit 12 to, for example, a stationary terminal installed in a room where a worker is stationary, or a mobile terminal owned by a worker, so that the temporal changes in the health of the main circuit unit 12 can be viewed on an external device. In this case, the monitoring device 14 may communicate with the external device via the communications unit and output the temporal changes in the health of the main circuit unit 12 to the external device in response to a request from the external device.

However, the method by which the monitoring device 14 can check 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 changes in the check results over time may be used.

In this way, 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, workers inspecting the power conversion device 10 need only inspect the main circuit unit 12 if a change in its health is detected, and can omit the inspection if no change in the health of the main circuit unit 12 has occurred. In this example, the degree of deterioration of the charge storage element 23 can be easily grasped, and inspection of the health of the charge storage element 23 can be omitted. The effort of inspecting the charge storage element 23 and checking its degree of deterioration can be omitted.

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 inspection work. For example, it is possible to shorten the inspection work time and reduce the costs required for 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 inspection work, thereby suppressing the impact on the operation of the power conversion device 10.

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 control of 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.

When checking the integrity 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 with two converters, the first converter 21 and the second converter 22, and may be configured with a single converter. The main circuit unit 12 may be configured in any way that includes at least a converter that converts AC power to DC power or 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.

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 unit 32 and a monitoring device 34 , and further includes a control device 36 .

The main circuit unit 32 converts power. The main circuit unit 32 has multiple switching elements 40. In other words, the multiple switching elements 40 are semiconductor elements. The main circuit unit 32 converts power by switching the multiple switching elements 40.

The main circuit unit 32 has, for example, six switching elements 40 connected in a three-phase bridge, 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. By switching each switching element 40, the main circuit unit 32 performs at least one of the following: conversion from three-phase AC power to DC power, and conversion from DC power to three-phase AC power. The main circuit unit 32 is, for example, a three-phase bridge converter.

However, the configuration of the main circuit unit 32 is not limited to a three-phase bridge converter. The main circuit unit 32 may be configured in any way that has multiple switching elements 40 and converts power by switching the multiple switching elements 40. The main circuit unit 32 may also 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.

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

The main circuit unit 32 further has multiple drive circuits 46 for driving each of the multiple switching elements 40. The main circuit unit 32 inputs multiple control signals input from the control device 36 to the corresponding multiple drive circuits 46. The multiple drive circuits 46 drive the switching of the corresponding switching elements 40 based on the input control signals.

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. The OFF state does not necessarily have to be 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 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. The multiple switching elements 40 may be self-excited switching elements or externally excited switching elements.

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

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 generating unit 52, a drive signal detector 54, and a light emitting element 56.

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.

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 in response to the electrical control signal input from the light-receiving element 50, and inputs this to the control terminal of the switching element 40, thereby driving the switching element 40 in response to the control signal.

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 response to the detection signal input from the drive signal detector 54, thereby inputting an optical feedback signal to the control device 36.

In this way, the multiple drive circuits 46 generate multiple drive signals in response to 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.

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

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. If 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.

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 is 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.

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

When an abnormality is detected, the control device 36, for example, notifies the user of the detected abnormality. The notification of the detected abnormality may be made by the control device 36, for example, by displaying the abnormality on a display unit, or may be made by an external device, such as a higher-level controller, by outputting the abnormality detection 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.

The monitoring device 34 acquires information on multiple control signals and multiple feedback signals as information related to the health of the main circuit unit 32. The monitoring device 34 checks the health of multiple drive circuits 46, for example, based on information on multiple control signals and multiple feedback signals.

The monitoring device 34 is connected to, for example, the control device 36, and acquires feedback signal information, such as feedback signals converted into electrical signals by the control device 36, as well as information on control signals, such as electrical signals input from the control device 36 to the drive circuit 46.

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.

Similar to the first embodiment described above, 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 a check is performed. As a result, the monitoring device 34 stores multiple check results obtained over time. By storing multiple check results obtained over time, the monitoring device 34 makes it possible to 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 with the first embodiment described above, any method may be used to check changes over time in the health of the multiple drive circuits 46.

In this way, with the power conversion device 30 according to this embodiment, even if no abnormality is detected by the control device 36, the monitoring device 34 can check the changes over time in the health of the multiple drive circuits 46, making it easy to understand the degree of deterioration of the multiple drive circuits 46.

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 changes over time in the health of the multiple drive circuits 46 using the monitoring device 34, it is possible to determine the degree of deterioration of the light-receiving element 50, light-emitting element 56, etc.

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

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

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 the signal line using a beam splitter, and converting them into electrical signals within the monitoring device 34. The information on the multiple control signals and the information on the multiple feedback signals may be any information that represents them. Furthermore, communication between the control device 36 and each drive circuit 46 is not limited to optical communication, and may also be communication using electrical signals, etc.

(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 .

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

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

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

Multiple current detectors 75, 76 are provided on the AC side of each of the multiple converters 71, 72, and detect the AC current values of each of the multiple converters 71, 72. The current detectors 75, 76 input information about the detected AC current values of each of the multiple converters 71, 72 to the monitoring device 64 and the control device 66.

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.

The control device 66 detects abnormalities 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 current 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 current detected by the current detectors 75, 76 is, in other words, the deviation in the amplitude of the AC current detected by the current detectors 75, 76.

If the control device 66 detects an abnormality in each converter 71, 72, it stops the operation of the main circuit unit 62. In other words, if the control device 66 detects an abnormality in each converter 71, 72, it stops the power conversion by each converter 71, 72, 73. Note that if the control device 66 detects an abnormality in each converter 71, 72, it may, for example, not be limited to stopping the main circuit unit 62, but may also issue an alert that an abnormality has been detected.

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, for example, checks the health of the multiple converters 71, 72 based on the information on the AC current values detected by the multiple current detectors 75, 76.

The monitoring device 64 stores the results of checking 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 check 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 check 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 deviation in the phase of the AC current detected by the current detectors 75, 76 may be stored as the check 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 phase of the AC current. However, the information stored as the check result is not limited to this, and may be any information that can be used to check the health of the multiple converters 71, 72 based on information about the AC current value.

As in the above embodiments, the monitoring device 64, for example, periodically or continuously checks the health of the main circuit unit 62 and stores the check results each time it checks. As a result, the monitoring device 64 stores multiple check results obtained over time. By storing multiple check results obtained over time, the monitoring device 64 makes it possible to 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 may be used to check changes over time in the health of the multiple converters 71, 72.

In the power conversion device 60 of this embodiment, even if the control device 66 does not detect an abnormality, the monitoring device 64 can check the changes in the health of the multiple converters 71, 72 over time, making it easy to understand the degree of deterioration of the multiple converters 71, 72.

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

As a result, in the power conversion device 60 according to this embodiment, it is possible to omit inspections of the health of the multiple converters 71, 72. If no abnormalities are detected by the control device 66, it is possible to avoid the need to inspect each converter 71, 72 and each current detector 75, 76 and check their degree of deterioration. Therefore, as with the above embodiments, it is possible to reduce the labor required for inspection work.

In this example, the monitoring device 64 acquires information on the AC current values detected by the multiple current detectors 75, 76 as information regarding 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.

Note that when the monitoring device 64 acquires information on the AC current values detected by the multiple current detectors 75, 76 as information regarding 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 each may be individually connected to a DC load, charge storage element, or the like. The main circuit unit 62 may be configured in any way 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.

In addition, in this example, the monitoring device 64 acquires information on AC current values from multiple current detectors 75, 76. The monitoring device 64 may, for example, acquire information on AC current values detected by the current detectors 75, 76 from the control device 66. The monitoring device 64 is not limited to a configuration in which it acquires AC current value information directly from multiple current detectors 75, 76, but may also be configured to acquire AC current value information via another device, etc.

(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.

The monitoring device 84 acquires information on the voltage values of the control terminals of each of the multiple switching elements 40 as information on the health of the main circuit section 82. In other words, the monitoring device 84 acquires information on the voltage values of multiple drive signals input from the multiple drive circuits 46 to the multiple switching elements 40 as information on the health of the main circuit section 82. Based on the acquired information on 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 multiple drive circuits 46 as changes over time in the health of the main circuit section 82.

The monitoring device 84, for example, is connected to the control terminals of each of the multiple switching elements 40 to obtain information about the voltage values of each 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 each of the control terminals of the multiple switching elements 40, and the monitoring device 84 may obtain information about the voltage values of each of the control terminals of the multiple switching elements 40 from the multiple voltage detectors. The method by which the monitoring device 84 obtains information about the voltage values of each of the control terminals of the multiple switching elements 40 may be any method that can appropriately obtain information about the voltage values of the control terminals.

The monitoring device 84 stores, for example, information on the voltage values of the control terminals of the multiple switching elements 40 that it has acquired. The voltages at 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 voltage at 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.

In this way, the monitoring device 84 may store information regarding the health of multiple main circuit sections 82 acquired over time, allowing it to check changes in the health of the main circuit sections 82 over time.

However, the information stored by 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 by 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.

In the power conversion device 80 of this embodiment, the monitoring device 84 checks the changes over time in the health of the multiple switching elements 40 and multiple drive circuits 46, making it easy to understand the degree of deterioration of the multiple switching elements 40 and multiple drive circuits 46.

As a result, with the power conversion device 80 according to this embodiment, it is possible to omit inspections of the health of the multiple switching elements 40 and multiple drive circuits 46. This eliminates the need to inspect the multiple switching elements 40 and multiple drive circuits 46 and check their degree of deterioration. For example, this eliminates the need for an operator to connect external devices during inspection of the multiple switching elements 40 and multiple drive circuits 46. Therefore, similar to the above embodiments, it is possible to reduce the labor required for inspection.

Fifth Embodiment
FIG. 7 is a block diagram schematically illustrating a power conversion device according to the fifth embodiment.
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 manner that converts power.

The camera device 96 photographs the exterior of the main circuit unit 92 and acquires the photographed images of the exterior of the main circuit unit 92. The camera device 96 inputs the acquired photographed images to the monitoring device 94. The camera device 96 is, for example, a fixed-point camera installed around the main circuit unit 92. The camera device 96 may also 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 device 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 equipped with, for example, multiple camera devices 96, and multiple photographed images taken by each of the multiple camera devices 96 may be input to the monitoring device 94. The photographed images input from the camera device 96 to the monitoring device 94 may be still images or moving images.

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 changes over time in the appearance of the main circuit section 92 as changes over time in the health of the main circuit section 92.

The monitoring device 94, for example, checks the external integrity of the main circuit section 92 based on information from captured images. When used over a long period of time, the components used in the main circuit section 92 can develop cracks due to thermal fatigue, or rust or discoloration due to the influence of the surrounding environment. Accumulated dust can also lead to malfunctions in the device. The monitoring device 94, for example, performs image processing on the information from the captured images to check the external integrity of the main circuit section 92 for the presence or absence of abnormalities in the main circuit section 92's appearance, such as cracks, rust, discoloration, or dust, and the extent of the abnormalities.

The monitoring device 94 stores the results of the confirmation of the external integrity of the main circuit section 92. The monitoring device 94 stores, for example, the results of image processing of the captured image as the confirmation result. The results of image processing may, for example, be stored as text information indicating whether or not there is an abnormality, or may store the degree of the abnormality in stages. The results of 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 integrity of the main circuit section 92 based on the information in the captured image.

As in the above 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. This allows the monitoring device 94 to store multiple check results acquired over time. By storing multiple check results acquired over time, the monitoring device 94 makes it possible to check changes in the external appearance of the main circuit unit 92 over time. As in the above embodiments, any method may be used to check changes in the external appearance of the main circuit unit 92 over time.

The monitoring device 94 may, for example, store information about the captured images acquired by the imaging device 96, as well as store multiple captured images acquired over time and display the multiple captured images side by side, thereby enabling changes in the appearance of the main circuit unit 92 over time to be confirmed. The monitoring device 94 does not necessarily have to perform image processing, etc.

In the power conversion device 90 of this embodiment, the monitoring device 94 can be used to check changes in the appearance of the main circuit section 92 over time, making it easy to understand the degree of deterioration in the appearance of the main circuit section 92.

As a result, with the power conversion device 90 according to this embodiment, inspection of the external appearance of the main circuit unit 92 can be omitted. For example, this eliminates 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, inspection work can be made less labor-intensive. Furthermore, for example, if signs of dust accumulation or the like appear, only the relevant areas need to be cleaned during inspection, thereby reducing the amount of work required during inspection.

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 configuration of the main circuit unit 102 may be any configuration that converts power.

The temperature detection device 106 detects the temperature of the main circuit section 102 and acquires temperature information related to the temperature of the main circuit section 102. The temperature detection device 106 inputs the acquired temperature information to the monitoring device 104.

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 section 102. The temperature detection device 106 detects, for example, the surface temperatures of multiple components used in the main circuit section 102. When the temperature detection device 106 is an infrared thermal imaging device, the temperature detection device 106 photographs the main circuit section 102 and acquires, as temperature information, a thermal image whose display mode changes depending on the surface temperature of the main circuit section 102. Examples of the display mode include the display color and color shading. The display mode may be any mode that allows the temperature to be identified on the image.

The monitoring device 104 acquires the temperature information obtained 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.

For example, if the temperature information is a thermal image, the monitoring device 104 confirms the temperature of the main circuit section 102 by performing image processing on the thermal image. The monitoring device 104 confirms the temperatures of multiple locations on the main circuit section 102 by performing image processing on the thermal image. In other words, the monitoring device 104 confirms the temperatures of multiple components used in the main circuit section 102 by performing image processing on the thermal image.

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

The monitoring device 104 may, for example, store thermal images acquired by the temperature detection device 106, as well as multiple thermal images acquired over time, and display multiple thermal images side by side, thereby enabling the temperature of the main circuit section 102 to be checked for changes over time. The monitoring device 104 does not necessarily have to perform image processing, etc.

A rise in the temperature of the components used in the main circuit section 102 can lead to component degradation or failure. Furthermore, the temperature of the components used in the main circuit section 102 can rise in response to component degradation or abnormalities. For this reason, in the power conversion device 100 according to this embodiment, the monitoring device 104 is able to monitor changes in the temperature of the main circuit section 102 over time. As a result, in the power conversion device 100 according to this embodiment, inspection of the main circuit section 102 can be omitted, for example, when there is no abnormal temperature rise. For example, if it is possible to monitor changes in the temperature of multiple components used in the main circuit section 102 over time, inspection of specific components can be omitted. Then, workers need only inspect the relevant areas when there is an abnormal temperature rise. Therefore, as with the above embodiments, inspection work can be reduced in labor.

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 components used in the main circuit section 102. The temperature detected by the temperature detection device 106 may be any temperature in the main circuit section 102. The temperature detection device 106 may be configured in any way that is capable of detecting the temperature of the main circuit section 102 and acquiring temperature information related to the temperature of the main circuit section 102.

The temperature information may be, for example, the detected temperature value of the main circuit section 102 detected by a temperature sensor. In this case, the monitoring device 104 may store multiple pieces of temperature information acquired over time, allowing the temperature of the main circuit section 102 to be checked for changes over time. The temperature information may be any information related to the temperature of the main circuit section 102.

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 configuration of the main circuit unit 112 may be any configuration that converts power.

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.

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 level of abnormal sound by analyzing the volume of the sound and the frequency components contained in the sound. The signal processing unit may detect whether abnormal sound is occurring in the main circuit unit 112, or may be able to identify the component in 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 any configuration that can detect abnormal sounds emitted from the main circuit unit 112 may be used. For example, the abnormal sound detection device 116 may include multiple microphones, allowing it to detect the level of abnormal sound from a specific component used in the main circuit unit 112.

The monitoring device 114 acquires the abnormal sound information obtained by the abnormal sound detection device 116 as information regarding the health 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 health of the main circuit section 112.

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 abnormal sound information, for example, periodically or continuously. The monitoring device 114 stores the acquired abnormal sound information, for example, 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, 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.

Abnormal noise emitted from the main circuit section 112 may become louder depending on the degree of deterioration of the components used in the main circuit section 112. Abnormal noise emitted from the main circuit section 112 may become louder due to, for example, deterioration or abnormalities in the cooling fan or reactor. For this reason, in the power conversion device 110 of this embodiment, the monitoring device 114 is able to check changes over time in abnormal noise emitted from the main circuit section 112. As a result, in the power conversion device 110 of this embodiment, inspection of the main circuit section 112 can be omitted when no abnormal noise is occurring. Then, workers or the like only need to inspect the main circuit section 112 when abnormal noise is occurring. Therefore, as with the above embodiments, inspection work can be reduced.

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.

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 into the monitoring device 124.

The odor detection device 126, for example, quantifies 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 quantified 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 quantifies and outputs odor intensity, but may also output 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, for example, may quantify the odor intensity for each type of odor around the main circuit unit 122 and output the odor information.

The monitoring device 124 acquires the odor information obtained by the odor detection device 126 as information regarding 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.

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 making it possible 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.

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

In configurations that include a camera device 96, temperature detection device 106, abnormal sound detection device 116, odor detection device 126, etc., introducing these devices may increase initial costs. However, by streamlining inspection work as described above, it is possible to reduce the cost of workers required for each inspection and the work time, including travel time to the site. Therefore, even if initial costs increase, it is possible to reduce overall lifecycle costs, including the cost required for inspections.

The above embodiments can be combined in any way. For example, by providing an image capture device 96 and a temperature detection device 106, the monitoring device can acquire image capture information and temperature information, allowing for confirmation of changes over time in the appearance of the main circuit unit and changes over time in the temperature of the main circuit unit. This can, for example, further reduce the labor required for inspection work.

In addition, the information regarding the health of the main circuit section acquired by the monitoring device is not limited to the above, and may be any information that allows for confirmation of changes in the health of the main circuit section over time.

While 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 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, and are also included in the scope of the invention and its equivalents as set forth in the claims.

DESCRIPTION OF SYMBOLS 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...Photographing device, 106...Temperature detection device, 116...Abnormal sound detection device, 126...Odor detection device

Claims (3)

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 . 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 : The monitoring device acquires the delay time of the feedback signal relative to the control signal and whether or not the feedback signal is lost over time, and stores information indicating the health of the plurality of drive circuits as a plurality of pieces of information arranged in chronological order. The power conversion device according to claim 1.