Monitoring system

Abstract

To provide a monitoring system capable of appropriately monitoring easiness of increase of an inverter device's temperature caused by driving an electric motor of a fluid machine.SOLUTION: A monitoring system performs monitoring operation on an inverter device for performing power conversion operation of drive power of an electric motor in a fluid machine using a switching element. The monitoring operation is operation of: monitoring specific information having correlation with easiness of increase of the inverter device's temperature caused by driving the electric motor; and determining whether or not the easiness of increase of the temperature has reached a predetermined reference condition.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present invention relates to a monitoring system that performs a monitoring operation for an inverter device that performs power conversion on driving power for an electric motor in a fluid machine. [Background Art]

[0002] Conventionally, fluid machines driven by an electric motor, such as electric air compressors, have been widely used. Such fluid machines are generally provided with an inverter device that performs power conversion on driving power for the electric motor.

[0003] The inverter device is also provided with a power module configured using a switching element such as an IGBT. For example, Patent Document 1 discloses a fluid machine having an inverter device that drives an electric motor, wherein the inverter device is provided with a power module (a module having a plurality of power switching elements such as IGBTs). Further, the inverter device is provided with a fan that promotes ventilation, enabling cooling of the power module and the like. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Unexamined Patent Application Publication No. 2017-180428 [Summary of the Invention] [Problem to be Solved by the Invention]

[0005] In the above-described fluid machine, particularly when the operating time is long under a condition of high outside air temperature, the temperature of the inverter device tends to become extremely high. In such a situation, the ventilation volume of the fan increases to promote cooling of the power module, and as a result, dust and the like tend to accumulate in ventilation openings and the like of the inverter device, which may cause the temperature of the inverter device to rise more easily.

[0006] If the inverter device overheats excessively, the likelihood of malfunctions in the switching elements increases, making maintenance of the inverter device recommended. Therefore, it is desirable to appropriately monitor how easily the inverter device overheats due to the driving of the electric motor in the fluid machinery.

[0007] Furthermore, even when using an inverter device that is configured to impose operational restrictions (stopping or limiting operation) when an abnormal temperature of the switching element is detected, it is desirable to take countermeasures before such operational restrictions are imposed, from the perspective of safe use of fluid machinery. This objective can be achieved by performing maintenance, etc., when the tendency for temperature to rise reaches a certain standard condition, before operational restrictions are imposed.

[0008] In view of the above-mentioned problems, the present invention aims to provide a monitoring system that can appropriately monitor the tendency of an inverter device to overheat due to the driving of an electric motor in a fluid machine. [Means for solving the problem]

[0009] The monitoring system according to the present invention relates to an inverter device that performs power conversion operations for the driving power of an electric motor in a fluid machine using a switching element, Data acquisition operation and A monitoring system that performs monitoring operations, The fluid machine is configured such that the drive of the electric motor is controlled by a control device, the inverter device is set to stop or limit the power conversion operation when the temperature of the switching element exceeds a predetermined upper limit temperature, and a temperature sensor is installed inside it to detect the cooling capacity by ventilation, and the data acquisition operation is an operation to acquire time-series monitoring data of the drive signal of the electric motor and the temperature detected by the temperature sensor. The aforementioned monitoring operation is, Based on the drive signal and the detected temperature, Drive of the aforementioned electric motor The detected temperature at that time shall be the effective temperature value, and the effective temperature value We monitor specific information that has a correlation with the likelihood of an increase, The effective temperature value Determine whether the ease of increase has reached a predetermined standard condition. Based on the determination result, the preventive maintenance flag for performing maintenance on the cooling system of the inverter device is updated from off to on. This configuration allows for the following operation: With this configuration, it becomes possible to appropriately monitor how easily the temperature of the inverter device rises due to the driving of the electric motor of the fluid machine.

[0010] More specifically, the above configuration includes the monitoring operation, The effective temperature value but Lower than the aforementioned upper limit temperatureThe frequency of exceeding a predetermined standard temperature is monitored as specific information, and it is determined whether or not that frequency has reached a predetermined value. Based on the determination result, the preventive maintenance flag is updated from off to on. It may also be configured as an operation that performs the following actions. More specifically in the above configuration, the monitoring operation is: The effective temperature value This is monitored as the aforementioned specific information, and Effective temperature value but Lower than the aforementioned upper limit temperature Determine whether or not the predetermined reference temperature has been reached. Based on the determination result, the preventive maintenance flag is updated from off to on. It can also be structured as an action.

[0011] More specifically, the above configuration is: The monitoring operation involves monitoring the effective temperature value as specific information, determining whether the moving average value of the effective temperature value has reached a predetermined reference temperature lower than the upper limit temperature, and updating the preventive maintenance flag from off to on based on the determination result. The structure is also good.

[0012] More specifically, the above configuration is formed by providing a power module equipped with the switching element and a cooling fin adjacent to the power module inside a ventilated housing, and the detected temperature is attached to the cooling fin. The aforementioned It is also acceptable to configure the system so that the temperature is detected by a temperature sensor.

[0013] More specifically, the above configuration is formed by providing a power module equipped with the switching element and cooling fins adjacent to the power module inside a ventilated housing, and the temperature detection sensor is attached to the surface of the power module on the side not adjacent to the cooling fins. The aforementioned It is also acceptable to configure the system so that the temperature is detected by a temperature sensor.

[0014] More specifically, the above configuration is such that the inverter device is provided with a power module equipped with the switching element and cooling fins adjacent to the power module, all located inside a ventilated housing, and a fan provided near the exhaust port of the housing is used to promote heat dissipation from the cooling fins to the outside of the exhaust port, and the temperature sensor is located between the cooling fins and the fan. The aforementionedA configuration in which the temperature is detected by a temperature sensor may be adopted.

[0015] More specifically, the above configuration includes: each communication unit provided corresponding to each of the plurality of inverter devices; and a server capable of communicating with each of the communication units, wherein each communication unit is configured to transmit the corresponding inverter device The aforementioned time-series monitor data obtained from to the server, and the server receives the data from each of the communication units The aforementioned time-series monitoring data based on which, performs a monitoring operation for each of the plurality of inverter devices The aforementioned specific information A configuration for performing a monitoring operation may be adopted. [Advantageous Effects of Invention]

[0016] According to the monitoring system of the present invention, it is possible to appropriately monitor the tendency of temperature rise of an inverter device caused by driving of an electric motor of a fluid machine. [Brief Description of the Drawings]

[0017] [Figure 1] 1 is a schematic configuration diagram of a monitoring system 900 according to the present embodiment. [Figure 2] 2 is a schematic configuration diagram of an air compressor 100 according to the present embodiment. [Figure 3] 3 is an exploded perspective view showing a schematic configuration example of an inverter 7 according to the present embodiment. [Figure 4] 4 is a schematic side sectional view of the inverter 7 exemplified in FIG. 3. [Figure 5] 5 is a flowchart related to a data collection operation. [Figure 6] 6 is a flowchart related to a situation determination operation. [Mode for Carrying Out the Invention]

[0018] Hereinafter, one embodiment of the present invention will be described with reference to the drawings. The monitoring system according to this embodiment is a system that performs monitoring operations with respect to inverter devices (inverter 7, described later) installed in each of the multiple air compressors (a form of fluid machine).

[0019] 1. Configuration of the monitoring system, etc. First, the configuration of the monitoring system according to this embodiment will be described. Figure 1 illustrates a schematic configuration of the monitoring system 900 according to this embodiment. The monitoring system 900 is configured to include a LAN (Local Area Network) 300 and a server 500. The LAN 300 is configured to include a mesh-type wireless network 210.

[0020] The wireless network 210 is a communication network composed of communication devices (nodes) consisting of a slave unit (hereinafter referred to as "communication unit 200"), a repeater 201, and a master unit 202, each of which is provided in a one-to-one correspondence with each of the multiple air compressors 100. The wireless network 210 enables wireless communication between multiple nodes located within a local area, such as a factory, and in cases where radio waves cannot reach directly, the nodes in between can relay the signals to enable mutual communication.

[0021] One of the features of the wireless network 210's communication protocol is its multi-hop function, which allows packets to be sent to the target node by passing through multiple nodes (hopping). Therefore, even when a communication unit 200 is installed in a location where radio waves are difficult to reach due to distance or other reasons, mutual communication with other nodes becomes possible by installing a repeater 201. Furthermore, when adding a new communication unit 200, the burden of wiring work is reduced, and the communication network can be easily expanded. In addition, by arranging the nodes in a mesh pattern, even if a node fails, communication can still be maintained through other functioning nodes.

[0022] In LAN300, all communication units 200 are connected to a master unit 202 via a wireless network 210, and the master unit 202 is further connected to a server 500 via a data line termination device 203 and the internet 400. This allows the server 500 to communicate with each communication unit 200. Information transmitted from each communication unit 200 is sent to the server 500 via LAN300 and the internet 400.

[0023] In this way, the monitoring system 900 can have the server 500 collect the information transmitted from each communication unit 200. Furthermore, if necessary, another LAN can be connected to the server 500 via the internet 400 to expand the scale of the monitoring system 900.

[0024] Each communication unit 200 is capable of communicating with the corresponding air compressor 100 (control device 10, described later), and can acquire a set of monitor data (monitoring results data for each item) related to the inverter device of the air compressor 100, and transmit this set of monitor data, along with the device ID, to the server 500. The device ID is information that allows the air compressor 100 to be identified by other air compressors 100, and can also be seen as information that allows the inverter device of the air compressor 100 to be identified by the inverter devices of other air compressors 100.

[0025] The server 500 can monitor each inverter device in the multiple air compressors 100 based on the information received from each communication unit 200. The server 500 has the device IDs for all air compressors 100 pre-registered, and can record information for each device ID. The operation of the monitoring system 900 will be explained in detail later.

[0026] 2. Air compressor configuration, etc. Next, we will explain the configuration of the air compressor 100. Figure 2 shows a schematic configuration of the air compressor 100.

[0027] As shown in this figure, the air compressor 100 has a configuration in which the following elements are arranged inside the housing 20: a compression mechanism 1, an oil separator 2, an automatic temperature control valve 3, an oil cooler 4, an oil filter 6, an inverter 7, an intake filter 8, a cooling fan 9, and a control device 10. The compression mechanism 1 includes a compressor body 51 and an electric motor 52, etc.

[0028] In this embodiment, the air compressor 100 is configured as an oil-lubricated air compressor, and the compressor body 51 compresses the air Aa drawn in from the outside into compressed air Ab, which can then be discharged to, for example, various pneumatic devices. The air compressor 100 can employ various configurations as long as they do not depart from the spirit of the present invention, and may also be configured as an oil-free air compressor.

[0029] Furthermore, the housing 20 is formed to allow ventilation through a dust filter for removing dust from the atmosphere. More specifically, at least a portion of the housing 20 is provided with vents that allow for ventilation between the inside and outside, and the dust filter is positioned to cover these vents from the outside.

[0030] In Figure 2, the white arrows schematically show the paths of air Aa and compressed air Ab, and the thick arrow schematically shows the lubricating oil circulation circuit X through which the lubricating oil Lu circulates. In this embodiment, the compressed air Ab that comes out of the compressor body 51 is discharged to the outside through the oil separator 2. The lubricating oil circulation circuit X shown in Figure 2 is a path that circulates the lubricating oil Lu by passing through predetermined locations (such as the compressor body 51) in the compression mechanism 1 where friction reduction and cooling are performed using the lubricating oil Lu.

[0031] The lubricating oil circulation circuit X has a path through which lubricating oil Lu flows from the compressor body 51 to the compressor body 51, passing sequentially through the oil separator 2, automatic temperature control valve 3, oil cooler 4, and oil filter 6. The lubricating oil circulation circuit X also has an auxiliary path Xa connecting the position between the oil cooler 4 and oil filter 6 to the automatic temperature control valve 3.

[0032] The compressor body 51 is driven by an electric motor 52 and operates to compress air Aa to produce compressed air Ab. In this embodiment, a rotary (screw) compressor is used as the compressor body 51, and the compressor body 51 uses lubricating oil Lu to reduce friction and cool the screw rotor (remove compression heat and frictional heat). The electric motor 52 is configured to be driven by AC power supplied from an external source (such as commercial power) and drives the rotor of the compressor body 51.

[0033] The compressed air Ab generated by the compressor body 51 contains lubricating oil Lu. Therefore, the oil separator 2 receives the compressed air Ab from the compressor body 51, separates the lubricating oil Lu contained in this compressed air Ab, and temporarily stores it. The portion of the lubricating oil circulation circuit X from the compressor body 51 to the oil separator 2 is the path for the lubricating oil Lu contained in the compressed air Ab.

[0034] The automatic temperature control valve 3 is a three-way valve that plays a role in regulating the temperature of the lubricating oil Lu. In this embodiment, the automatic temperature control valve 3 operates, for example, to increase the amount of lubricating oil Lu passing through the auxiliary path Xa when the temperature of the lubricating oil Lu is lower than a predetermined reference value. This reduces the amount of lubricating oil Lu passing through the oil cooler 4, thereby suppressing the temperature drop of the lubricating oil Lu.

[0035] The oil cooler 4 includes a water-cooled oil cooler that cools the lubricating oil Lu by water cooling, and an air-cooled oil cooler that cools the lubricating oil Lu by air cooling. The water-cooled oil cooler recovers waste heat contained in the lubricating oil Lu, and while primary cooling the lubricating oil Lu through heat exchange with the cooling water, it also warms the cooling water. The warm water generated by the water-cooled oil cooler is used in the factory as boiler feedwater, etc.

[0036] The air-cooled oil cooler is configured to allow the lubricating oil Lu to pass through after it has passed through the water-cooled oil cooler, and to secondarily cool the lubricating oil Lu through heat exchange between the lubricating oil Lu and cooling air (outside air drawn into the housing 20 by the operation of the cooling fan 9). The oil cooler 4 may have only one of the water-cooled oil cooler or the air-cooled oil cooler. The oil filter 6 is a filter that removes impurities such as iron rust and sludge from the lubricating oil Lu.

[0037] The lubricating oil Lu circulating in the lubricating oil circulation circuit X first plays a role in reducing friction in the compressor body 51, and then flows into the oil separator 2 where it is separated from the compressed air Ab. This lubricating oil Lu is temporarily stored in the oil separator 2, and then cooled as it passes through the automatic temperature control valve 3 and the oil cooler 4. After impurities are removed from this cooled lubricating oil Lu in the oil filter 6, it flows into the compression mechanism 1 where it is used for friction reduction and cooling where necessary, and then returns to the compressor body 51.

[0038] Furthermore, the compressed air Ab separated by the oil separator 2 is cooled by an aftercooler (not shown) located inside the housing 20 before being supplied to the outside. The aftercooler preferably includes a water-cooled aftercooler that cools the compressed air Ab by water cooling, and an air-cooled oil cooler that cools the compressed air Ab by air cooling. The water-cooled aftercooler recovers the waste heat contained in the compressed air Ab, and while primary cooling the compressed air Ab through heat exchange between the compressed air Ab and the cooling water, it also warms the cooling water. The cooling water may be supplied in series to the water-cooled oil cooler and the water-cooled aftercooler, or in parallel.

[0039] The air-cooled aftercooler is configured to pass the compressed air Ab that has passed through the water-cooled aftercooler, and to secondarily cool the compressed air Ab through heat exchange between the compressed air Ab and the cooling air (outside air drawn into the enclosure 20 by the operation of the cooling fan 9). The aftercooler may consist of only one of the two types: a water-cooled aftercooler or an air-cooled aftercooler.

[0040] The inverter 7 is a device (inverter device) that performs power conversion operations on AC power supplied from an external source to the electric motor 52. The operation of the inverter 7 can be controlled by the control device 10, which in turn allows the control device 10 to control the drive frequency of the electric motor 52. The higher the drive frequency, the higher the rotational speed of the electric motor 52, and the greater the amount of compressed air Ab produced by the compressor body 51.

[0041] The intake filter 8 is installed in the intake path of air Aa to the compressor body 51 and is a filter that removes dust. The air Aa drawn in from outside the housing 20 has dust removed as it passes through the intake filter 8 and is then sent to the compressor body 51. The cooling fan 9 is a fan that promotes ventilation so that the inside of the housing 20 is cooled, and also blows cooling air to the air-cooled oil cooler and air-cooled aftercooler mentioned above.

[0042] The control device 10 controls and monitors each part of the air compressor 100 to ensure that the air compressor 100 operates normally. The control device 10 can also communicate with the communication unit 200 (see Figure 1) which is compatible with the air compressor 100.

[0043] The control device 10 controls the drive frequency of the electric motor 52 according to, for example, the demand for compressed air Ab. This allows the drive frequency to be increased as the demand for compressed air Ab increases, thereby generating more compressed air Ab. The control device 10 can also continuously output a motor drive signal Sm, which is a contact signal for driving / stopping the electric motor 52. The motor drive signal Sm is ON when the electric motor 52 is driving and OFF when the electric motor 52 is stopped. The control device 10 also drives the cooling fan 9 to maintain a constant temperature in a predetermined location inside the housing 20 (for example, inside the oil separator 2).

[0044] Here, the inverter 7 in this embodiment will be described in more detail. Figure 3 is an exploded perspective view showing a schematic configuration example of the inverter 7. Note that the front, back and up and down directions shown in Figure 3 are merely for illustrative purposes. As shown in Figure 3, the inverter 7 includes an inverter case 111, a main control board 112, a power module 113, cooling fins 114 (heat sink), a vent 115, a cooling fan 116, and a cooling fan cover 117.

[0045] The inverter case 111, together with the ventilation opening 115, forms a ventilated enclosure, and the main control board 112, power module 113, and cooling fins 114 are housed inside this enclosure. A cooling fan 116 and a cooling fan cover 117 are provided near the rear end of the inverter case 111, and the ventilation opening 115 is provided near the front end of the inverter case 111. One or both of the ventilation opening 115 and the cooling fan cover 117 may be integrated with the inverter case 111.

[0046] A power module 113 is located near the main control board 112, and cooling fins 114 are located on the underside of the power module 113. The main control board 112 has a controller that controls various parts of the inverter 7 according to instructions from the control device 10. The power module 113 is also equipped with multiple switching elements such as IGBTs used for power conversion.

[0047] Figure 4 shows a schematic side cross-sectional view of the inverter 7 in the configuration example shown in Figure 3. Note that the inverter case 111 is not shown in Figure 4. In the inverter 7, the cooling fan 116 rotates, generating an airflow from front to rear, as indicated by the white arrows in Figure 4. That is, air is drawn from outside the inverter 7 through the vent 115 to the cooling fins 114 and passes between the many fins of the cooling fins 114. At this time, the heat generated from the power module 113 is transferred to the air through the fins, and the power module 113 is cooled. The air that has absorbed heat from the cooling fins 114 is exhausted to the outside of the inverter 7 through the exhaust port provided in the cooling fan cover 117.

[0048] As described above, the inverter 7 is formed by providing a power module 113 equipped with switching elements such as IGBTs, and cooling fins 114 adjacent to the power module 113, inside a ventilated housing. Furthermore, the inverter 7 is configured to use a cooling fan 116 provided near the exhaust port of the housing to promote heat dissipation from the cooling fins 114 to the outside of the exhaust port.

[0049] Furthermore, a temperature sensor St (e.g., a thermocouple) is installed inside the inverter 7 to acquire data on the detected temperature Tm, which will be described later. The position of this temperature sensor St can be determined by considering various factors, but the following three examples are preferred.

[0050] The first example shows how to install a temperature sensor St so that the surface temperature of the cooling fins 114 is detected. The second example shows how to position the temperature sensor St so that the temperature of the space between the cooling fins 114 and the cooling fan 116 is detected. The third example shows how to install a temperature sensor St so that the temperature of the surface of the power module 113 on the side not adjacent to the cooling fins 114 (such as the side where the cooling fins 114 are not located) is detected.

[0051] In the first example, the detected temperature Tm is the temperature detected by the temperature sensor St attached to the cooling fin 114. In this example, it is desirable to place the temperature sensor St in contact with the tip of the fin so as not to obstruct the airflow between the fins. In the second example, the detected temperature Tm is the temperature detected by the temperature sensor St placed between the cooling fin 114 and the cooling fan 116, making it possible to detect the exhaust temperature.

[0052] In the third example, the detected temperature Tm is the temperature detected by the temperature sensor St attached to the surface of the power module 113 on the side not adjacent to the cooling fin 114, making it possible to detect the temperature of the power module 113 with particular accuracy. The detected temperature Tm information is continuously sent to the control device 10. If temperature information of the power module 113 (temperature information of the switching element) can be obtained via the controller of the inverter 7, this temperature information can be used instead of the detected temperature Tm. In this case, it is possible to omit the placement of the temperature sensor St on the inverter 7.

[0053] Furthermore, the inverter 7 is equipped with a function to monitor the temperature of switching elements such as IGBTs that make up the power module 113 in order to prevent damage to these switching elements due to overheating. With this function, if the temperature of the switching elements exceeds a predetermined upper limit temperature Tu, the inverter 7 is set to issue an alarm and then stop or limit the power conversion operation as described above.

[0054] When the outside temperature is high and the air compressor 100 is operated for a long time, the amount of ventilation inside the inverter 7 increases to promote cooling of the power module 113, making the cooling fins 114 and vents 115 more prone to becoming dirty with dust. As a result, the cooling capacity for the power module 113 decreases, causing the temperature of the inverter 7 to rise more easily and leading to more frequent malfunctions. In addition, if multiple cooling fans 116 are installed in the inverter case 111, if some of the cooling fans 116 have insufficient airflow or malfunction due to component lifespan, these can cause the temperature of the inverter 7 to rise more easily and may lead to malfunctions.

[0055] Therefore, the monitoring system 900 focuses on how easily the temperature of the inverter 7 rises due to the driving of the electric motor 52 and determines whether maintenance of the inverter 7 is necessary. The specific details of the operation of the monitoring system 900 will be explained below.

[0056] 3. Operation of the monitoring system, etc. The monitoring system 900 performs monitoring operations regarding the necessity of maintenance for the inverter 7 in each air compressor 100. In this embodiment, the monitoring system 900 performs data collection operations, which cause the server 500 to collect a group of monitor data M for the inverter 7 in each air compressor 100, and status determination operations, which determine whether predetermined conditions have been met based on the group of monitor data M.

[0057] First, the data acquisition operation will be explained below with reference to the flowchart shown in Figure 5. When the main power supply of the corresponding air compressor 100 is turned ON, each communication unit 200 starts the operation of acquiring the monitor data group M related to the inverter 7 (step S11). In this embodiment, the monitor data group M includes the motor drive signal Sm and the detected temperature Tm monitor data as described above. Each monitor data includes values ​​(time-series data) that are acquired sequentially in synchronization at a predetermined period (for example, every minute), and all values ​​in each monitor data are accompanied by information on the date and time when the value was acquired. Each communication unit 200 continuously receives and acquires the monitor data group M from the control device 10 of the corresponding air compressor 100 and temporarily records it until it is transmitted to the server 500.

[0058] Furthermore, each communication unit 200 performs the operation to acquire the monitor data group M while monitoring for the timing to transmit the monitor data group M (step S12). Whenever this transmission timing arrives (Yes in step S12), each communication unit 200 transmits the monitor data group M newly recorded since the previous transmission, along with the device ID of the corresponding air compressor 100, to the server 500 (step S13). In this embodiment, each communication unit 200 is configured to transmit the monitor data group M to the server 500 at regular intervals (for example, intervals of 30 to 120 minutes), and transmits the newly recorded monitor data group M to the server 500 at each of these intervals.

[0059] Meanwhile, the server 500 waits to receive the monitor data group M and device ID from each communication unit 200 (step S21). Each time the server 500 receives the monitor data group M and device ID from any of the communication units 200 (Yes in step S21), the server 500 records the detected temperature Tm when the motor drive signal Sm is ON as the effective temperature value Tv for that device ID (step S22).

[0060] By performing this series of data collection operations (steps S11 to S22), it is possible to have the server 500 collect information on the effective temperature value Tv for the inverter 7 in each air compressor 100. The effective temperature value Tv can be seen as the temperature detected by the inverter 7 when the electric motor 52 is in operation.

[0061] Next, the situation determination operation will be explained below with reference to the flowchart shown in Figure 6. This situation determination operation can be performed periodically, for example, at a predetermined frequency (one example being once a day).

[0062] The server 500 first sets the first device ID from among all the pre-registered device IDs as the processing target ID (step S31). As mentioned above, the server 500 has the device IDs for all air compressors 100 pre-registered.

[0063] The server 500 then determines whether the frequency Y in which the effective temperature value Tv exceeds the preventive maintenance determination temperature Tp for the current processing target ID has reached a predetermined threshold Sa (step S32). This preventive maintenance determination temperature Tp (a form of the reference temperature according to the present invention) is set to a temperature lower than the upper limit temperature Tu (the temperature at which the power conversion operation of the inverter 7 is stopped or limited) mentioned above. A specific example of the operation in step S32 is the operation of determining whether the number of times the effective temperature value Tv has exceeded the preventive maintenance determination temperature Tp within the most recent predetermined period (for example, a predetermined period within the range of 1 to 2 weeks) has reached a predetermined number of times (for example, a predetermined number within the range of 5 to 10 times).

[0064] As a result, if the frequency Y does not reach the threshold Sa (No in step S32), the server 500 then determines whether the moving average value Z of the effective temperature value Tv has reached the preventive maintenance determination temperature Tp (step S33). A specific example of the operation in step S33 is the operation of calculating the moving average value Z for a predetermined number of consecutive effective temperature values ​​Tv (for example, 10 times) and determining whether this moving average value Z has reached the preventive maintenance determination temperature Tp.

[0065] As a result, if the moving average value Z has not reached the preventive maintenance determination temperature Tp (No. in step S33), the server 500 sets the next device ID (a device ID that has not yet been set as a processing target ID) as the processing target ID (step S35), and then performs the operation in step S32 again.

[0066] On the other hand, if the frequency Y reaches the preventive maintenance determination temperature Tp during the operation in step S32 (Yes in step S32), or if the moving average value Z reaches the preventive maintenance determination temperature Tp during the operation in step S33 (Yes in step S33), the server 500 updates the preventive maintenance flag for the current processing target ID to "ON" (step S34).

[0067] In other words, the server 500 has pre-recorded and stored information on a preventive maintenance flag (initial value is "OFF") indicating whether maintenance of the inverter 7 is necessary for each device ID, and the preventive maintenance flag corresponding to the current processing target ID is updated to "ON" by the operation in step S34. After performing the operation in step S34, the server 500 sets the next device ID (a device ID that has not yet been set as a processing target ID) as the processing target ID (step S35), and then performs the operation in step S32 again. If all device IDs have already been set as processing target IDs by the time the operation in step S35 is performed, this status determination operation is terminated.

[0068] By performing this series of situation determination operations (steps S31 to S35), the server 500 can use the effective temperature value Tv to determine whether the ease with which the temperature of the inverter 7 in each air compressor 100 rises has reached a predetermined standard condition.

[0069] The status of the preventive maintenance flag for each device ID, which is recorded and stored on server 500, can be checked by the business operator (facility management agent) responsible for the maintenance of each air compressor 100, making it easy to determine which air compressor 100 requires maintenance of its inverter 7. For example, a field engineer performing maintenance work under the aforementioned business operator can incorporate maintenance of the cooling system of the inverter 7 in the corresponding air compressor 100 (cleaning of the vents 115 (cleaning and replacement of the dust filter if present), cleaning of the cooling fins 114, cleaning and replacement of the cooling fan 116, etc.) into their action plan when the preventive maintenance flag for a particular device ID is turned ON. Furthermore, the preventive maintenance flag that has been turned "ON" can be updated to "OFF" after the maintenance is performed, thereby enabling further monitoring.

[0070] 4. Others As described above, the monitoring system 900 according to this embodiment is a monitoring system that performs monitoring operations with respect to the inverter 7, which performs power conversion operations for the driving power of the electric motor 52 in the air compressor 100 (a form of fluid machine) using switching elements. Furthermore, this monitoring operation monitors specific information that has a correlation with how easily the temperature of the inverter 7 rises due to the driving of the electric motor 52, and determines whether or not the ease with which the temperature rises has reached a predetermined standard condition. Therefore, the monitoring system 900 makes it possible to appropriately monitor how easily the temperature of the inverter 7 rises due to the driving of the electric motor 52 of the air compressor 100.

[0071] Furthermore, the monitoring system 900 monitors the frequency Y at which the effective temperature value Tv exceeds a predetermined reference temperature α as specific information, and in the operation of step S32 described above, it determines whether or not the frequency Y has reached a predetermined value. In this way, by monitoring the frequency at which the internal temperature of the inverter 7 rises too high as specific information, it is possible to easily monitor how easily the temperature of the inverter 7 rises due to the driving of the electric motor 52.

[0072] Furthermore, the monitoring system 900 monitors the effective temperature value Tv as specific information, and in the operation of step S33 described above, it determines whether the moving average value Z of the effective temperature value Tv has reached a predetermined reference temperature α. In this way, by monitoring the tendency for the internal temperature of the inverter 7 to rise too much as specific information, it is possible to easily monitor how easily the temperature of the inverter 7 rises due to the driving of the electric motor 52.

[0073] In this embodiment, both steps S32 and S33 are executed, but only one of them may be executed. Also, in this embodiment, a preventive maintenance determination temperature Tp lower than the upper limit temperature Tu (the temperature at which the power conversion operation of the inverter 7 is stopped or limited) is applied as the reference temperature α. Therefore, by performing the necessary maintenance when the preventive maintenance flag is turned ON, it is possible to prevent the internal temperature of the inverter 7 from rising to the upper limit temperature Tu.

[0074] The monitoring system 900 also includes a communication unit 200, each corresponding to an inverter 7 in a plurality of air compressors 100, and a server 500 capable of communicating with each communication unit 200. Each communication unit 200 transmits information on the detected temperature of the corresponding inverter 7 to the server 500, and the server 500 performs monitoring operations for each of the plurality of inverters 7 based on the information received from each communication unit 200.

[0075] Therefore, according to the monitoring system 900, the server 500 can monitor each inverter 7 in multiple air compressors 100, enabling efficient monitoring. Furthermore, if, for example, multiple air compressors 100 are distributed throughout the factory, the data transmitted from the communication unit 200 to the server 500 may include location information of the air compressor 100 corresponding to that communication unit 200.

[0076] In this embodiment, an air compressor was used as an example of a fluid machine, but the present invention is also applicable to monitoring systems that perform monitoring operations on inverter devices installed in other fluid machines. For example, the present invention is also applicable to monitoring systems that perform monitoring operations on inverter devices installed in the outdoor unit of a heat pump water heater (a fluid machine that drives a fan motor with an inverter) or in the blower of a cooling tower (a fluid machine that drives a fan motor with an inverter).

[0077] Although embodiments of the present invention have been described above, the configuration of the present invention is not limited to the above embodiments, and various modifications can be made without departing from the spirit of the invention. In other words, the above embodiments should be considered to be illustrative in all respects and not restrictive. The technical scope of the present invention is indicated not by the above description of embodiments, but by the claims, and should be understood to include all modifications that fall within the meaning and scope equivalent to the claims. [Explanation of Symbols]

[0078] 1. Compression mechanism 2 Oil Separator 3. Automatic temperature control valve 4. Oil cooler 6. Oil filter 7 Inverter 8. Intake filter 9 Cooling fan 10 Control device 20 cabinets 30 Air Filter 51 Compressor body 52 Electric motor 100 Air Compressor 200 communication units 201 Repeater 202 Main Unit 203 Data Line Termination Equipment 210 Wireless Networks 300 LAN 400 Internet 500 servers 900 monitoring systems Aa Air Ab Compressed air Lu Lubricant X Lubricating oil circulation circuit Xa Auxiliary path

Claims

1. Regarding an inverter device that performs power conversion operations for the drive power of an electric motor in a fluid machine using switching elements, a monitoring system that performs data acquisition and monitoring operations, The fluid machine is configured such that the drive of the electric motor is controlled by a control device. The inverter device is configured such that the power conversion operation is stopped or limited when the temperature of the switching element exceeds a predetermined upper temperature, and a temperature sensor is installed inside it to detect the cooling capacity by ventilation. The data acquisition operation is an operation to acquire time-series monitoring data of the drive signal of the electric motor and the temperature detected by the temperature sensor. The aforementioned monitoring operation is, Based on the drive signal and the detected temperature, the detected temperature during operation of the electric motor is set as the effective temperature value, and specific information having a correlation with the ease with which the effective temperature value rises is monitored. A monitoring system characterized by determining whether the ease with which the effective temperature value rises has reached a predetermined standard condition, and updating a preventive maintenance flag for performing maintenance on the cooling system of the inverter device from off to on based on the determination result.

2. The aforementioned monitoring operation is, The frequency with which the effective temperature value exceeds a predetermined reference temperature lower than the upper limit temperature is monitored as specific information. The monitoring system according to claim 1, characterized in that it determines whether the frequency has reached a predetermined value and updates the preventive maintenance flag from off to on based on the determination result.

3. The aforementioned monitoring operation is, The effective temperature value is monitored as the specified information. The monitoring system according to claim 1, characterized in that it determines whether the effective temperature value has reached a predetermined reference temperature lower than the upper limit temperature, and updates the preventive maintenance flag from off to on based on the determination result.

4. The aforementioned monitoring operation is, The effective temperature value is monitored as the specified information. The monitoring system according to claim 1, characterized in that it determines whether the moving average value of the effective temperature has reached a predetermined reference temperature lower than the upper limit temperature, and updates the preventive maintenance flag from off to on based on the determination result.

5. The inverter device is, The power module equipped with the switching element and the cooling fins adjacent to the power module are formed by providing them inside a ventilated housing. The detected temperature is, The monitoring system according to any one of claims 2 to 4, characterized in that the temperature is detected by the temperature sensor attached to the cooling fin.

6. The inverter device is, The power module equipped with the switching element and the cooling fins adjacent to the power module are formed by providing them inside a ventilated housing. The detected temperature is, The monitoring system according to any one of claims 2 to 4, characterized in that the temperature is detected by the temperature sensor attached to the surface of the power module on the side not adjacent to the cooling fin.

7. The inverter device is, The power module equipped with the switching element and the cooling fins adjacent to the power module are provided inside a ventilated housing, The cooling fins are designed to facilitate the dissipation of heat from the exhaust port to the outside of the exhaust port by using a fan provided near the exhaust port of the housing. The detected temperature is, The monitoring system according to any one of claims 2 to 4, characterized in that the temperature is detected by the temperature sensor placed between the cooling fins and the fan.

8. Each of the multiple inverter devices is provided with a corresponding communication unit, The system includes a server capable of communicating with each of the aforementioned communication units, Each of the aforementioned communication units transmits the time-series monitoring data acquired from the corresponding inverter device to the server. The monitoring system according to claim 2 or 3, characterized in that the server performs monitoring operations for each of the plurality of inverter devices based on the time-series monitoring data received from each of the communication units.

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