Power conversion device, cooling abnormality determination device, and cooling abnormality determination method

Abstract

To provide a technique capable of appropriately determining some failure concerning cooling performance of a power device by a cooling structure such as cooling fins of a power conversion apparatus.SOLUTION: A power conversion apparatus 100 includes: a power device (a semiconductor diode SD and a semiconductor switch SW); a cooling structure 190 for radiating heat of the power device; a cooling fan 180 for blowing air to the cooling structure 190; and a controller 140 for determining whether or not some failure exists in the cooling performance by the cooling structure 190 on the basis of a temperature difference Y between a temperature (a fin temperature Tf) of the cooling structure 190 (a cooling fin part 194) and a temperature (an inner air temperature Ta) in the power conversion apparatus 100 (an enclosure).SELECTED DRAWING: Figure 12

Description

Technical Field

[0001] The present disclosure relates to a power conversion device and the like.

Background Art

[0002] For example, in a power conversion device that converts externally input power into power with a predetermined voltage or a predetermined frequency and drives a load device, a method for determining cooling anomalies such as clogging of a cooling structure portion for heat dissipation of a power device is disclosed (see Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in Patent Document 1 described above, based on changes in the temperatures themselves at a plurality of locations measured within the power conversion device, cooling anomalies such as clogging of the cooling fins are determined. Therefore, since there is a possibility that the influence due to fluctuations in the load state of the power conversion device is superimposed on the measured temperature changes, the accuracy of determining cooling anomalies by the cooling fins may decrease.

[0005] In addition, in Patent Document 2 described above, when a heating state occurs, the power conversion device is forcibly stopped, and in addition to the temperature inside the power conversion device, using the load state of the power conversion device, cooling abnormalities such as clogging of the intake air port that sucks air toward the cooling fins are determined. Therefore, although an improvement in determination accuracy can be expected in consideration of the load state of the power conversion device, it is premised on the occurrence of a heating abnormality in which the power conversion device is forcibly stopped, and it is not possible to determine a cooling abnormality at a stage before the power conversion device is forcibly stopped.

[0006] Therefore, in view of the above problems, an object is to provide a technology capable of more appropriately determining an abnormality related to the cooling performance of a power device by a cooling structure portion such as a cooling fin of a power conversion device.

Means for Solving the Problems

[0007] To achieve the above object, in one embodiment of the present disclosure, a power device; a cooling structure portion for radiating heat of the power device; a blower portion that blows air to the cooling structure portion; a determination portion that makes a determination regarding the abnormality based on the fact that the degree of abnormality in the cooling performance by the cooling structure portion increases as the temperature difference between the temperature of the cooling structure portion and the temperature of the air inside the power conversion device increases, and the determination portion Correct the measured value of the temperature difference to the temperature difference when the power device is in a predetermined load state, and based on the corrected temperature difference, determine whether there is an abnormality. At the same time, determines that there is the abnormality when the temperature difference exceeds a predetermined first reference value. A power conversion device is provided.

[0008] In another embodiment of the present disclosure, Regarding a power conversion device including a power device, a cooling structure portion for radiating heat of the power device, and a blower portion that blows air to the cooling structure portion, a cooling abnormality determination device that makes a determination regarding the abnormality based on the fact that the degree of abnormality in the cooling performance by the cooling structure portion increases as the temperature difference between the temperature of the cooling structure portion and the temperature of the air inside the power conversion device increases, Correct the measured value of the temperature difference to the temperature difference when the power device is in a predetermined load state, and based on the corrected temperature difference, determine whether there is an abnormality. At the same time, When the temperature difference exceeds a predetermined first reference value, it is determined that there is an abnormality. A cooling abnormality determination device is provided.

[0009] Further, in still another embodiment of the present disclosure, Regarding a power conversion device including a power device, a cooling structure portion for radiating heat of the power device, and a blower portion for blowing air to the cooling structure portion, based on the fact that the degree of abnormality of the cooling performance by the cooling structure portion increases as the temperature difference between the temperature of the cooling structure portion and the temperature of the air inside the power conversion device increases, a cooling abnormality determination method for making a determination regarding the abnormality, Correct the measured value of the temperature difference to the temperature difference when the power device is in a predetermined load state, and based on the corrected temperature difference, determine whether there is an abnormality. At the same time, When the temperature difference exceeds a predetermined first reference value, it is determined that there is an abnormality. A cooling abnormality determination method is provided.

Advantages of the Invention

[0010] According to the above-described embodiment, it is possible to more appropriately determine an abnormality regarding the cooling performance of the power device by a cooling structure portion such as a cooling fin of the power conversion device.

Brief Description of the Drawings

[0011]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Mode for Carrying Out the Invention

[0012] Hereinafter, embodiments will be described with reference to the drawings.

[0013] [Configuration of Cooling Abnormality Determination System] First, with reference to FIGS. 1 and 2, the configuration of the cooling abnormality determination system 1 according to the present embodiment will be described.

[0014] FIG. 1 is a diagram showing an example of the configuration of the cooling abnormality determination system 1 according to the present embodiment. FIG. 2 is a diagram showing an example of the configuration of the control device 140 in the cooling abnormality determination system 1 according to the present embodiment.

[0015] The cooling abnormality determination system 1 according to the present embodiment determines the presence or absence of an abnormality regarding the cooling performance of the power conversion device 100.

[0016] As shown in FIG. 1, the cooling abnormality determination system 1 includes a power conversion device 100, an arithmetic device 200, and a terminal device 300.

[0017] The power conversion device 100 converts three-phase AC power (for example, the R phase, S phase, and T phase) input from the commercial power supply PS into three-phase AC power (for example, the U phase, V phase, and W phase) having a predetermined voltage and a predetermined frequency, and drives the motor M.

[0018] Based on the three-phase AC power output from the power conversion device 100, the motor M drives a predetermined machine such as a take-up machine installed in a textile factory by electric drive.

[0019] In addition, the power conversion device 100 may generate three-phase AC power for driving the motor M based on three-phase AC power input from a power source other than the commercial power supply. Further, the power conversion device 100 may generate three-phase AC power for driving the motor M based on the power input from a DC power source. In this case, the DC power is input to a DC link section (positive line PL and negative line NL) between a rectifier circuit 110 and an inverter circuit 130 described later.

[0020] The power conversion device 100 includes a rectifier circuit 110, a smoothing circuit 120, an inverter circuit 130, a control device 140, a sensor 150, a display device 160, a communication device 170, and a cooling fan 180.

[0021] The rectifier circuit 110 is configured to rectify the three-phase AC power of the R phase, S phase, and T phase input from the commercial power supply PS and output DC power. The rectifier circuit 110 has its positive and negative output terminals connected to one ends of the positive line PL and the negative line NL, respectively, and can output DC power to the smoothing circuit 120 through the positive line PL and the negative line NL. The rectifier circuit 110 includes, for example, six semiconductor diodes SD (an example of a power device) (see FIG. 3), and is a bridge-type full-wave rectifier circuit in which three series-connected bodies of two semiconductor diodes SD constituting the upper and lower arms are connected in parallel.

[0022] The smoothing circuit 120 suppresses and smooths the pulsation of the DC power output from the rectifier circuit 110 and the DC power regenerated from the inverter circuit 130.

[0023] The smoothing circuit 120 includes, for example, a smoothing capacitor.

[0024] The smoothing capacitor may be provided in a path connecting the positive line PL and the negative line NL in parallel with the rectifier circuit 110 and the inverter circuit 130.

[0025] The smoothing capacitor appropriately smoothes the DC power output from the rectifier circuit 110 and the DC power output (regenerated) from the inverter circuit 130 while repeatedly charging and discharging.

[0026] There may be one smoothing capacitor. Also, a plurality of smoothing capacitors may be arranged, and a plurality of smoothing capacitors may be connected in parallel or in series between the positive line PL and the negative line NL. Further, a plurality of smoothing capacitors may be configured in such a manner that a plurality of series-connected bodies of two or more smoothing capacitors are connected in parallel between the positive line PL and the negative line NL.

[0027] Also, the smoothing circuit 120 includes, for example, a reactor.

[0028] The reactor may be provided on the positive line PL between the rectifier circuit 110 and the smoothing capacitor (specifically, the branch point with the path where the smoothing capacitor is arranged).

[0029] The reactor appropriately smoothes the DC power output from the rectifier circuit 110 and the DC power output (regenerated) from the inverter circuit 130 while generating a voltage so as to impede the change in current.

[0030] The inverter circuit 130 has its positive and negative input terminals connected to the other ends of the positive line PL and the negative line NL. The inverter circuit 130 converts the DC power supplied from the smoothing circuit 120 into three-phase AC power (for example, the U-phase, V-phase, and W-phase) having a predetermined frequency and a predetermined voltage by the switching operation of the semiconductor switch SW (an example of a power device) (see Fig. 3) and outputs it to the motor M. The semiconductor switch SW may be, for example, an IGBT (Insulated Gate Bipolar Transistor) or a MOSFET (Metal-Oxide-Semiconductor Field-Effect Transistor) made of silicon (Si). Further, the semiconductor switch SW may be, for example, a semiconductor element using a wide-bandgap semiconductor such as silicon carbide (SiC) or gallium nitride (GaN).

[0031] The inverter circuit 130 includes, for example, six semiconductor switches SW, and is configured in a form including a bridge circuit in which series-connected bodies (switch legs) of two semiconductor switches SW constituting the upper and lower arms are connected in parallel in three sets between the positive line PL and the negative line NL. Then, the inverter circuit 130 may output three-phase AC power through the U-phase line, V-phase line, and W-phase line drawn from the connection points of the three sets of upper and lower arms. Further, freewheeling diodes may be connected in parallel to the six semiconductor switches SW, respectively.

[0032] The control device 140 performs control related to the power conversion device 100.

[0033] The function of the control device 140 may be realized by any hardware or any combination of hardware and software, etc.

[0034] The control device 140 is mainly configured by a computer including, for example, a CPU 141 (Central Processing Unit), a memory device 142, a non-volatile auxiliary storage device 143, and an interface 144 as shown in FIG. 2. The control device 140 performs various controls by loading a program installed in the auxiliary storage device 143 into the memory device 142 and causing the CPU 141 to execute it. Further, the control device 140 receives external signals or outputs (transmits) signals to the outside through the interface 144.

[0035] As shown in FIG. 2, the memory device 142 includes RAMs (Random Access Memories) 142A and 142B.

[0036] The auxiliary storage device 143 includes a ROM (Read Only Memory) 143A and an EEPROM (Electrically Erasable Programmable Read-Only Memory) 143B. A ring buffer RB described later is set in the EEPROM 143B (an example of a storage unit).

[0037] Note that the ring buffer RB may be set in the RAM 142A or the RAM 142B.

[0038] The control device 140 (an example of a determination unit and a cooling abnormality determination device) outputs a drive signal to the inverter circuit 130 (specifically, the gates of the respective semiconductor switches SW), and drives the electric motor M to satisfy a predetermined operating condition using the inverter circuit 130. In other words, the control device 140 generates a control signal for driving the electric motor M along a predetermined operating condition and outputs it to the inverter circuit 130.

[0039] Further, the control device 140 determines whether there is an abnormality regarding the cooling performance of the power conversion device 100. Specifically, it determines whether there is an abnormality regarding the cooling performance of the cooling structure unit 190 for dissipating heat generated by the losses during energization of the semiconductor diode SD and the semiconductor switch SW described later. Details will be described later.

[0040] The sensor 150 acquires detection information regarding the operating state (operation state) of the power conversion device 100. The sensor 150 is connected to the control device 140, for example, through a one-to-one communication line or the like, and a signal corresponding to the detection information (hereinafter, “detection signal”) is taken into the control device 140. Thereby, the control device 140 can perform control regarding the power conversion device 100 based on the detection signal of the sensor 150.

[0041] The sensor 150 includes, for example, various temperature sensors. The temperature sensors may include, for example, a cooling fin temperature sensor that detects the temperature of a cooling fin portion 194 described later (hereinafter, “fin temperature”) Tf. Further, the temperature sensors may include, for example, an internal air temperature sensor that detects the temperature of the air inside the housing of the power conversion device 100 (hereinafter, “internal air temperature”) Ta.

[0042] Also, the sensor 150 includes, for example, various current sensors, voltage sensors, and the like. The current sensors may include, for example, a load current sensor that detects a load current IL output to the electric motor M.

[0043] The display device 160 (an example of a notification unit and a display unit) is provided, for example, on the outer surface of the housing of the power conversion device 100. The display device 160 displays information regarding the operating state (operation state) of the power conversion device 100 under the control of the control device 140.

[0044] Note that the display device 160 may be provided outside the housing of the power conversion device 100, for example, on the surface (outer surface) of the housing of a predetermined machine that is electrically driven by the electric motor M.

[0045] The communication device 170 (an example of a notification unit) communicates with external devices of the power conversion device 100, such as the arithmetic device 200 and the terminal device 300, through a predetermined communication line.

[0046] The predetermined communication line may be, for example, a one-to-one communication line. Further, the predetermined communication line may include, for example, a local area network (LAN) such as a field network constructed within a facility (factory) where a predetermined machine driven by an electric motor M is installed. The local area network may be constructed by wire, wirelessly, or may include both. Further, the predetermined communication line may include, for example, a wide area network (WAN) outside the facility (factory) where a predetermined machine driven by an electric motor M is installed. The wide area network may include, for example, a mobile communication network with a base station at the end, a satellite communication network using communication satellites, the Internet network, etc. Further, the predetermined communication line may include, for example, a short-distance communication line according to a predetermined wireless communication standard such as Bluetooth (registered trademark) or WiFi.

[0047] Note that the function of the communication device 170 may be incorporated into the control device 140 (interface 144).

[0048] The cooling fan 180 (an example of the air blowing unit) blows air to the cooling structure unit 190 (specifically, the cooling fin unit 194) described later, and promotes heat dissipation by the cooling structure unit 190.

[0049] The housing of the power conversion device 100 is provided with an outside air intake port (air intake port) and an inside air discharge port (exhaust port). The cooling fan 180 may be provided upstream of the cooling structure portion 190 in the path of the air flow from the intake port to the exhaust port. In this case, the cooling fan 180 sucks outside air from the intake port and sends it toward the cooling structure portion 190, thereby applying the relatively low-temperature outside air to the cooling structure portion 190 and discharging the air heated by heat exchange with the cooling structure portion 190 from the exhaust port. Further, the cooling fan 180 may be provided downstream of the cooling structure portion 190 in the path of the air flow from the intake port to the exhaust port. In this case, the cooling fan 180 sucks out the air around the cooling structure portion 190 and creates a flow of air from the upstream intake port toward the cooling structure portion 190, thereby applying the relatively low-temperature outside air to the cooling structure portion 190.

[0050] The arithmetic unit 200 (an example of a second external device) is provided outside the power conversion device 100 and performs various arithmetic processes.

[0051] The arithmetic unit 200 may be communicably connected to the power conversion device 100 through a predetermined communication line, for example, and perform arithmetic processes related to the control of the power conversion device 100 in response to a command from the control device 140. Specifically, the arithmetic unit 200 may perform some or all of the arithmetic processes related to the determination of cooling abnormality, which will be described later, in response to a command from the control device 140.

[0052] The arithmetic unit 200 may be, for example, a PLC (Programmable Logic Controller) or an edge controller for controlling a predetermined machine electrically driven by the electric motor M. Further, the arithmetic unit 200 may be, for example, a computer terminal.

[0053] Further, the arithmetic unit 200 may be, for example, a server device. The server device may be a cloud server installed outside a facility (factory) where a predetermined machine electrically driven by the electric motor M is installed. Further, the server device may be, for example, an edge server installed inside a facility (factory) where a predetermined machine electrically driven by the electric motor M is installed, or in a communication facility (e.g., a base station or a station building) near the facility.

[0054] The terminal device 300 (an example of the first external device) is provided outside the power conversion device 100 and is used by a user of the power conversion device 100 (cooling abnormality determination system 1). The terminal device 300 provides various information to the user, receives various inputs from the user, and transmits them to the power conversion device 100, for example, through the display unit 310.

[0055] The terminal device 300 may include, for example, a stationary terminal device such as a desktop computer terminal. Further, the terminal device 300 may include a portable (portable) terminal device (portable terminal) such as a smartphone, a tablet terminal, or a laptop computer terminal.

[0056] [Cooling Structure of Power Conversion Device] Next, with reference to FIG. 3, the cooling structure portion 190 of the power conversion device 100 will be described.

[0057] FIG. 3 is a schematic diagram showing an example of the cooling structure portion 190 of the power conversion device 100.

[0058] The cooling structure portion 190 corresponds to, for example, a heat sink and includes a fin base 192 and a cooling fin portion 194.

[0059] The fin base 192 has a flat plate shape with a predetermined thickness. The cooling fin portion 194 is provided on one surface (the lower surface in the figure) of the flat plate shape of the fin base 192, and circuit boards 110A and 130A corresponding to the rectifier circuit 110 and the inverter circuit 130, respectively, are placed on the other surface (the upper surface in the figure).

[0060] The fin base 192 is composed of a member with relatively high thermal conductivity. Thereby, the heat energy generated by the loss during energization of the semiconductor diode SD and the semiconductor switch SW can be easily released to the fin base 192. The fin base 192 may be composed of a metal such as aluminum, iron, copper, etc. The same may apply to the cooling fin portion 194 below.

[0061] As described above, the cooling fin portion 194 is provided on one surface of the flat plate shape of the fin base 192. The cooling fin portion 194 includes a plurality of fins 194A protruding in a direction away from the surface of the fin base 192 (in the negative Z-axis direction in the figure).

[0062] Each of the plurality of fins 194A has a very thin flat plate shape and is arranged at substantially equal intervals along a predetermined direction (the X-axis direction in the figure) on one surface of the fin base 192.

[0063] Each of the plurality of fins 194A is composed of a member with relatively high thermal conductivity. Thereby, the heat energy generated by the loss during energization of the semiconductor diode SD and the semiconductor switch SW can be easily released from the fin base 192 to the plurality of fins 194A. Also, the plurality of fins 194A have a relatively large surface area. Thereby, the contact area between the plurality of fins 194A and the air can be made relatively large, and the heat energy can be easily radiated to the surrounding air. Therefore, the heat energy generated by the loss during energization of the semiconductor diode SD and the semiconductor switch SW can be easily radiated to the air, and the cooling performance of the power conversion device 100 can be improved.

[0064] Further, due to the action of the cooling fan 180, the cooling air CA flows in a direction (Y-axis direction in the figure) perpendicular to the direction (X-axis direction) in which the plurality of fins 194A are arranged. As a result, the cooling air CA passes between the plurality of fins 194A, and the temperature of the air around the plurality of fins 194A is maintained in a relatively low state. Therefore, the temperature difference between the fins 194A and the surrounding air becomes relatively large, making it easier to radiate heat energy to the surrounding air. Thus, it becomes easier to radiate the heat energy generated by the losses during energization of the semiconductor diode SD and the semiconductor switch SW to the air, and by further improving the cooling performance of the power conversion device 100, the cooling performance required for the power conversion device 100 can be ensured.

[0065] On the other hand, depending on the environment in which the power conversion device 100 is installed, foreign matter may clog between the plurality of fins 194A. Also, depending on the size of the foreign matter, there is a possibility that the intake port of the housing of the power conversion device 100 may be clogged with foreign matter. For example, in a textile factory, not only dust but also cotton may be contained in the air, and cotton or the like may clog between the plurality of fins 194A or the intake port of the housing of the power conversion device 100. Then, the cooling air CA may not hit the fins 194A corresponding to the part where the foreign matter is clogged, or the amount of outside air inhaled from the intake port may decrease, and the temperature of the air supplied to the cooling fin portion 194 may increase. Therefore, the cooling performance of the semiconductor diode SD and the semiconductor switch SW by the cooling structure portion 190 deteriorates, and as a result, an abnormality (hereinafter, "cooling abnormality") regarding the cooling performance of the power conversion device 100 (semiconductor diode SD and semiconductor switch SW) by the cooling structure portion 190 occurs. And depending on the degree of the cooling abnormality, it may be necessary to forcibly stop the power conversion device 100, which may affect the operation of a factory where a predetermined machine electrically driven by the electric motor M is installed.

[0066] Furthermore, the cooling structure 190 may be in any form as long as it can promote the dissipation of heat energy generated by the losses during energization of the semiconductor diode SD and the semiconductor switch SW to the surrounding air. For example, the fin 194A may be one instead of a plurality. Also, on the fin base 192, instead of the fin 194A, one or more rod-shaped or needle-shaped protrusions made of a member with relatively high thermal conductivity may be provided.

[0067] [An Example of the Operation Regarding the Determination of Cooling Abnormality of the Power Conversion Device] Next, with reference to FIGS. 4 to 9, an example of the operation regarding the determination of cooling abnormality of the power conversion device 100 will be described.

[0068] In this example, the control device 140 diagnoses cooling abnormalities (hereinafter, for convenience, referred to as "clogging abnormalities") due to foreign matter clogging between the cooling fin portions 194 (a plurality of fins 194A) or at the air intake port of the housing of the power conversion device 100. The function (hereinafter, the "cooling fin clogging diagnosis function") for the control device 140 to diagnose clogging abnormalities such as the cooling fin portions 194 may be configured to be switchable between an effective state (ON state) and an ineffective state (OFF state) according to an input received from the outside. For example, the user may switch the cooling fin clogging diagnosis function between the ON state and the OFF state through a predetermined input unit provided in the power conversion device 100 or a predetermined machine electrically driven by the electric motor M. Also, for example, the user may switch the cooling fin clogging diagnosis function between the ON state and the OFF state through a predetermined input to the terminal device 300. In this case, a signal corresponding to the content of the input in the terminal device 300 is transmitted to the power conversion device 100 through a predetermined communication line and taken into the control device 140 through the communication device 170. Thereby, the control device 140 can switch the ON state and the OFF state of the cooling fin clogging diagnosis function according to the input from the user.

[0069] Specifically, the control device 140 determines the clogging abnormality of the cooling fin unit 194 based on the temperature difference Y between the fin temperature Tf and the internal air temperature Ta. When foreign matter clogs the intake port of the cooling fin unit 194 or the power conversion device 100, it becomes difficult for the wind to hit the fins 194A. As a result, the heat energy of the fins 194A is insufficiently radiated to the air, and the temperature difference Y becomes relatively large (increases).

[0070] <Control Processing for Cooling Abnormality Judgment> Figs. 4 to 8 are diagrams showing an example of the control processing related to the cooling abnormality judgment by the control device 140. Specifically, Fig. 4 is a flowchart schematically showing an example of the data acquisition processing related to the cooling abnormality judgment by the control device 140. Fig. 5 is a flowchart schematically showing an example of the end processing related to the cooling abnormality judgment by the control device 140. Fig. 6 is a flowchart schematically showing an example of the start processing related to the cooling abnormality judgment by the control device 140. Fig. 7 is a flowchart schematically showing an example of the cooling abnormality judgment processing by the control device 140. Fig. 8 is a flowchart schematically showing an example of the cooling abnormality mitigation judgment processing by the control device 140.

[0071] First, the flowchart of Fig. 4 is repeatedly executed at a predetermined control cycle, for example, during the operation of the power conversion device 100, that is, from the start of operation (specifically, the power-on of the control device 140) to the stop of operation (specifically, the power-off of the control device 140). The same may apply to the flowchart of Fig. 12 described later.

[0072] As shown in Fig. 4, in step S102, the control device 140 (CPU 141) determines whether the cooling fin clogging diagnosis function is in the ON state. If the CPU 141 determines that the cooling fin clogging diagnosis function is in the ON state, it proceeds to step S104. If it is in the OFF state, the processing of this flowchart is terminated.

[0073] The cooling fin clogging diagnosis function may also be fixed in an always-enabled state. In this case, the process of step S102 is omitted. The same applies to step S702 in FIG. 12 described later.

[0074] In step S104, the CPU 141 calculates a temperature difference Y (= Tf - Ta) between the fin temperature Tf and the internal air temperature Ta as a determination index for the presence or absence of clogging abnormality in the cooling fin portion 194.

[0075] The CPU 141 may calculate the temperature difference Y, for example, based on the difference between the measured value of the fin temperature Tf by the fin temperature sensor and the measured value of the internal air temperature Ta by the internal air temperature sensor. Hereinafter, the temperature difference Y obtained from the difference between the measured value of the fin temperature Tf by the fin temperature sensor and the measured value of the internal air temperature Ta by the internal air temperature sensor may be referred to as the "measured value of the temperature difference Y".

[0076] Further, the CPU 141 may correct the measured value of the temperature difference Y to the value of the temperature difference Y in a predetermined load state (hereinafter, "reference load state") of the reference power conversion device 100. Thereby, to some extent, the influence of the load state of the power conversion device 100 can be removed from the temperature difference Y as a determination index for the clogging abnormality of the cooling fin portion 194. This is because the fin temperature Tf changes depending on the load state of the power conversion device 100, that is, the heat generation state generated from the losses of the semiconductor diode SD and the semiconductor switch SW, and the ambient environment temperature.

[0077] For example, the CPU 141 may correct the measured value of the temperature difference Y based on the estimated value of the junction temperature Tj, and obtain a corrected value of the temperature difference Y in the reference load state of the power conversion device 100. This is because it is known that the junction temperature Tj does not change due to factors such as the air volume to the cooling fin portion 194, and changes according to the load state of the power conversion device 100. Specifically, the CPU 141 may estimate (calculate) the losses of power devices (semiconductor diode SD and semiconductor switch SW), for example, and obtain (calculate) an estimated value of the junction temperature Tj based on the estimated losses. Then, the CPU 141 may obtain a corrected value of the temperature difference Y from the measured value of the temperature difference Y and the estimated value of the junction temperature Tj using a conversion formula, a conversion map, or the like for obtaining the corrected value of the temperature difference Y.

[0078] Also, for example, the CPU 141 may correct the measured value of the temperature difference Y based on the measured value of the load current IL by the load current sensor, and obtain a corrected value of the temperature difference Y in the reference load state of the power conversion device 100. This is because the magnitude of the load current IL changes according to the load state of the power conversion device 100. Specifically, the CPU 141 may calculate the load state (load factor) of the power conversion device 100 using a conversion formula or a conversion map based on the measured value of the load current IL. Then, the CPU 141 may obtain a corrected value of the temperature difference Y from the measured value of the temperature difference Y and the calculated value of the load state of the power conversion device 100 using a conversion formula, a conversion map, or the like for obtaining the corrected value of the temperature difference Y. Further, the CPU 141 may convert the measured value of the load current IL into an index value in the unit of temperature for correcting the temperature difference Y, and obtain a corrected value of the temperature difference Y using the index value.

[0079] Note that the above conversion formula and conversion map are defined in advance, for example, through experiments, simulations, etc. related to the power conversion device 100.

[0080] When the process of step S104 is completed, the CPU 141 proceeds to step S106.

[0081] In step S106, the CPU 141 determines whether the temperature difference Y calculated in step S104 exceeds a reference value Yth1. The reference value Yth1 (an example of a first reference value) may be defined in advance, for example, as a lower limit value that can be determined as clogging occurring in the cooling fin portion 194 through experiments, simulations, or the like. Further, the reference value Yth1 may be defined in advance based on at least one of a logical method and an approximate method based on, for example, the temperature difference Y when the cooling performance by the cooling structure portion 190 is in a predetermined normal state and the temperature difference Y when the cooling fan 180 is stopped. Further, the reference value Yth1 is set to a value somewhat lower than a reference value Yth2 (an example of a second reference value) corresponding to the temperature difference Y when the power conversion device 100 is forcibly stopped due to a cooling abnormality of the power conversion device 100. When the temperature difference Y exceeds the reference value Yth1, the CPU 141 proceeds to step S108, and when it does not exceed the reference value Yth1, the processing of the current flowchart ends.

[0082] In step S108, the CPU 141 determines whether the temperature difference Y calculated in step S104 exceeds a maximum temperature difference Ymax. The maximum temperature difference Ymax corresponds to the maximum value of the temperature difference Y recorded in a ring buffer RB defined in advance in a predetermined storage area of the EEPROM 143B and is stored in the RAM 142B (see FIG. 6). When the temperature difference Y calculated in step S104 exceeds the maximum temperature difference Ymax, the CPU 141 proceeds to step S110, and when it does not exceed the maximum temperature difference Ymax, the processing of the current flowchart ends.

[0083] In step S110, the CPU 141 sets the maximum temperature difference Ymax to the temperature difference Y calculated in the current step S104. Thereby, the CPU 141 can use the temperature difference Y of the current flowchart as the maximum temperature difference Ymax after the next flowchart.

[0084] When the processing of step S110 is completed, the CPU 141 proceeds to step S112.

[0085] In step S112, the CPU 141 stores the current operating time OT, as well as the current fin temperature Tf, the internal air temperature Ta, and the temperature difference Y in the RAM 142B. The operating time OT represents the operating time of the power conversion device 100 since the previous reset. As will be described later, since the operating time OT is reset (cleared) when a temperature difference Y exceeding the past maximum temperature difference Ymax is recorded in the ring buffer RB (see FIG. 5), it corresponds to the operating time of the power conversion device 100 since the previous maximum temperature difference Ymax was obtained. The CPU 141 can calculate the operating time OT, for example, by reading the operating time OT at the end of the previous operation from the EEPROM 143B and integrating the operating time since the current startup based on the clock counter with the operating time OT at the end of the previous operation. The operating time OT may include the entire period from the startup to the stop of the power conversion device 100. Also, the operating time OT may be the time measured only during the period when the semiconductor diode SD and the semiconductor switch SW are energized among the entire period from the startup to the stop of the power conversion device 100.

[0086] When the processing in step S112 is completed, the CPU 141 proceeds to step S114.

[0087] Note that the maximum temperature difference Ymax may be updated multiple times during the operation of the power conversion device 100. In this case, when the operation of the power conversion device 100 stops, only the data corresponding to the latest temperature difference Y that updated the maximum temperature difference Ymax remains in the RAM 142B, and the other data does not remain. Therefore, when the operation of the power conversion device 100 stops, the data of the temperature difference Y remaining in the RAM 142B is larger than the maximum temperature difference Ymax until the previous operation stop and corresponds to the maximum value of the temperature difference Y during the current operation.

[0088] In step S114, the CPU 141 sets a new data available flag F1 in the RAM 142A (F1 = SET). Thereby, the CPU 141 can subsequently recognize that data of a temperature difference Y larger than both the reference value Yth1 and the maximum temperature difference Ymax is stored in the RAM 142B (see step S204 in FIG. 5 described later).

[0089] When the process of step S114 is completed, the CPU 141 ends the process of the current flowchart.

[0090] Note that the order of the processes in steps S112 and S114 may be reversed and is arbitrary.

[0091] As described above, in this example, during the operation of the power conversion device 100, when the temperature difference Y between the fin temperature Tf and the internal air temperature Ta exceeds both the reference value Yth1 and the maximum value of the past temperature differences Y (maximum temperature difference Ymax), the control device 140 can hold the temperature difference Y in the RAM 142B. Further, the control device 140 can hold the operating time OT corresponding to the operating time of the power conversion device 100 from when the temperature difference Y corresponding to the previous maximum temperature difference Ymax is acquired until the current temperature difference Y (i.e., the new maximum temperature difference Ymax) is acquired in the RAM 142B.

[0092] Subsequently, the flowchart of FIG. 5 is repeatedly executed, for example, at each predetermined control cycle during the operation of the power conversion device 100.

[0093] As shown in FIG. 5, in step S202, the CPU 141 determines whether or not it has detected that the power supply of the power conversion device 100 (control device 140) is OFF. When the CPU 141 detects that the power supply of the power conversion device 100 is OFF, it proceeds to step S204. When it does not detect that the power supply is OFF, it ends the process of the current flowchart.

[0094] Note that in this example, the ring buffer RB contains a number of buffers B (buffers B(1) to B(RPmax)) corresponding to a predetermined value RPmax which is an integer of 2 or more. Also, the ring buffer pointer RP represents the recording position of data among the plurality (predetermined value RPmax) of buffers B in the ring buffer RB, and the initial value is set to 1.

[0095] In step S204, the CPU 141 determines whether a new data present flag F1 is set in the RAM 142A. If the new data present flag F1 is set in the RAM 142A, the CPU 141 proceeds to step S206. If the new data present flag F1 is not set, the processing of the current flowchart ends.

[0096] In step S206, the CPU 141 records the operation time OT, and the data of the temperature difference Y, the fin temperature Tf, and the internal air temperature Ta stored in the RAM 142B in the ring buffer RB of the EEPROM 143B. Specifically, the above-mentioned data is recorded in B(RP) corresponding to the value of the current ring buffer pointer RP among a predetermined number RPmax of buffers B from buffer B(1) to buffer B(RPmax) of the ring buffer RB.

[0097] When the processing in step S206 is completed, the CPU 141 proceeds to step S208.

[0098] In step S208, the CPU 141 clears (resets) the operation time OT. As a result, starting from the recording of the current temperature difference Y, the measurement of the operation time OT is started from the next startup (power-on) of the power conversion device 100.

[0099] When the processing in step S208 is completed, the CPU 141 proceeds to step S210.

[0100] In step S210, the CPU 141 advances the ring buffer pointer RP set in the EEPROM 143B by one. Specifically, when the ring buffer pointer RP is smaller than the predetermined value RPmax, the ring buffer pointer RP is incremented by 1 (RP = RP + 1). On the other hand, when the ring buffer pointer RP is the predetermined value RPmax, the ring buffer pointer RP is reset to "1" (RP = 1). As a result, the CPU 141 can record data in the buffer B at the next position of the buffer B of the ring buffer RB where the current data was recorded at the next data recording.

[0101] When the process of step S210 is completed, CPU 141 proceeds to step S212.

[0102] In step S212, CPU 141 sets the ring buffer flag F2 in EEPROM 143B (F2 = SET). Thereby, CPU 141 can recognize that data is recorded in the ring buffer RB by referring to the ring buffer flag F2 in EEPROM 143B.

[0103] When the process of step S212 is completed, CPU 141 proceeds to step S214.

[0104] In step S214, CPU 141 clears the new data available flag F1 in RAM 142A.

[0105] When the process of step S214 is completed, CPU 141 ends the process of this flowchart.

[0106] Note that the order of the processes in steps S208 to S214 may be changed as appropriate and is arbitrary.

[0107] As described above, in this example, when the operation of the power conversion device 100 ends, CPU 141 can record, in the non-volatile ring buffer RB, the maximum temperature difference Y during the current operation, which is larger than the maximum temperature difference Ymax up to the previous time. In addition, CPU 141 can record, in the non-volatile ring buffer RB, the operation time OT corresponding to the operation time of the power conversion device 100 from when the previous maximum temperature difference Ymax was recorded until the temperature difference Y to be recorded this time is acquired.

[0108] Subsequently, FIG. 6 is executed, for example, when the operation of the power conversion device 100 is started (specifically, when the power of the control device 140 is turned on).

[0109] As shown in FIG. 6, in step S302, the CPU 141 determines whether data is recorded in the ring buffer, that is, whether the ring buffer flag F2 is set in the EEPROM 143B. If the ring buffer flag F2 is set, the CPU 141 proceeds to step S304; if the ring buffer flag F2 is not set, the processing of this flowchart ends.

[0110] In step S304, the CPU 141 reads the ring buffer pointer RP from the EEPROM 143B.

[0111] When the processing in step S304 is completed, the CPU 141 proceeds to step S306.

[0112] In step S306, the CPU 141 reads the latest fin temperature Tf, internal air temperature Ta, and temperature difference Y from the buffer B(RP) corresponding to the value of the ring buffer pointer RP in the ring buffer RB and stores them in the RAM 142B.

[0113] When the processing in step S306 is completed, the CPU 141 proceeds to step S308.

[0114] In step S308, the CPU 141 sets the read latest temperature difference Y as the maximum temperature difference Ymax in the RAM 142B.

[0115] When the processing in step S308 is completed, the CPU 141 ends the processing of this flowchart.

[0116] Thus, in this example, the CPU 141 acquires the latest data of the temperature difference Y stored in the ring buffer RB and sets it as the maximum temperature difference Ymax. Therefore, the CPU 141 can determine the increase in the temperature difference Y based on the latest temperature difference Y recorded until the previous operation stop, that is, the maximum temperature difference Y until the previous operation stop (see step S108 in FIG. 4).

[0117] Subsequently, the flowchart of FIG. 7 is executed at a predetermined timing. For example, the flowchart of FIG. 7 may be executed when the power conversion device 100 is started (when the power of the control device 140 is turned on) or stopped (when the power is turned off). Further, the flowchart of FIG. 7 may be executed during the operation of the power conversion device 100 when data such as the temperature difference Y of the RAM 142B is updated (see step S112 in FIG. 4). Also, for example, the flowchart of FIG. 7 may be configured to be manually executable in response to an input from the user. In this case, the input from the user may be received, for example, through an input unit provided in a predetermined machine electrically driven by the power conversion device 100 or the electric motor M, or may be received from the terminal device 300 through a predetermined communication line.

[0118] As shown in FIG. 7, the CPU 141 determines whether data is recorded in the ring buffer RB, that is, whether the ring buffer flag F2 is set in the RAM 142B. When the ring buffer flag F2 is set, the CPU 141 proceeds to step S404. When the ring buffer flag F2 is not set, the processing of this flowchart is terminated.

[0119] In step S404, the CPU 141 determines whether the fin temperature Tf stored in the RAM 142B is greater than the reference value Tf_th1. The reference value Tf_th1 is, for example, a lower limit value that can be determined in advance through experiments or simulations as a situation where clogging of foreign matter has occurred in the cooling fin portion 194. Also, the reference value Tf_th1 is set to a value somewhat lower than the reference value Tf_th2 corresponding to the fin temperature Tf when the fin temperature Tf becomes very high and the power conversion device 100 is forcibly stopped as the heating state of the cooling fin portion 194. Thereby, it is possible to determine the cooling abnormality of the power conversion device 100 before the power conversion device 100 is forcibly stopped. When the fin temperature Tf is greater than the reference value Tf_th1, the CPU 141 proceeds to step S406. When it is less than or equal to the reference value Tf_th1, the CPU 141 proceeds to step S408.

[0120] In step S406, the CPU 141 issues an alarm (hereinafter, "cooling fin clogging alarm") indicating that there is a possibility of clogging in the cooling fin portion 194 to the user.

[0121] The cooling fin clogging alarm may be issued to the user, for example, through the display device 160. Only the fact of the issuance of the cooling fin clogging alarm may be displayed on the display device 160. Further, in addition to the fact of the issuance of the cooling fin clogging alarm, data on the operating state (operation state) of the power conversion device 100 including the fin temperature Tf, the internal air temperature Ta, the temperature difference Y, etc., and data representing the history thereof may be displayed numerically on the display device 160. The data representing the history may be, for example, data representing the change in the temperature difference Y.

[0122] Also, the cooling fin clogging alarm may be issued to the user, for example, through the terminal device 300. In this case, a signal (hereinafter, "alarm signal") corresponding to the cooling fin clogging alarm output from the control device 140 is transmitted from the communication device 170 to the terminal device 300. Then, when the terminal device 300 receives the alarm signal, it notifies the user of the cooling fin clogging alarm through the display unit 310. Only the fact may be displayed on the terminal device 300 (display unit 310) in the same manner as when the cooling fin clogging alarm is issued through the display device 160, or data on the operating state of the power conversion device 100 may be displayed numerically together.

[0123] When the process of step S406 is completed, the CPU 141 proceeds to step S420.

[0124] On the one hand, in step S408, the CPU 141 determines whether the internal air temperature Ta stored in the RAM 142B is greater than the reference value Ta_th1. The reference value Ta_th1 is predefined, for example, through experiments or simulations, as the lower limit value that can determine that the internal air temperature of the power conversion device 100 deviates from the normal range. If the internal air temperature Ta is greater than the reference value Ta_th1, the CPU 141 proceeds to step S410; if it is less than or equal to the reference value Ta_th1, the CPU 141 proceeds to step S412.

[0125] In step S410, the CPU 141 issues both an alarm indicating that the internal air temperature is abnormal (hereinafter referred to as the "internal air abnormality alarm") and a cooling fin clogging alarm to the user.

[0126] Similar to the case of the cooling fin clogging alarm, the internal air abnormality alarm may be issued through the display device 160 or through the terminal device 300 (display unit 310). Also, similar to the case of the cooling fin clogging alarm, only the fact that the internal air alarm has been issued may be displayed on the display device 160 or the terminal device 300 (display unit 310), or alternatively, data regarding the operating state of the power conversion device 100 may be displayed numerically.

[0127] When the processing in step S410 is completed, the CPU 141 proceeds to step S420.

[0128] On the other hand, in step S412, the CPU 141 determines whether the number of data recorded in the ring buffer RB, that is, whether the number of buffers B among the buffers B(1) to B(RPmax) of the ring buffer RB in which data is recorded is equal to or greater than a predetermined number (for example, 4). If the number of data recorded in the ring buffer RB is equal to or greater than the predetermined number, the CPU 141 proceeds to step S414; if it is less than the predetermined number, the processing of this flowchart is terminated. This is because by performing the determination of cooling abnormality using as much data of the temperature difference Y as possible, the possibility of false determination of clogging abnormality in the cooling fin portion 194 can be suppressed.

[0129] In step S414, the CPU 141 approximately predicts the future temporal change of the temperature difference Y based on the data of the temperature difference Y and the operating time OT recorded in the ring buffer RB that is equal to or more than a predetermined number. Specifically, the CPU 141 predicts the required time TMest until the temperature difference Y reaches the reference value Yth2 when the power conversion device 100 is forced to stop.

[0130] For example, the CPU 141 may predict the future temporal change of the temperature difference Y by linear approximation based on the history of the temperature difference Y and the operating time OT, and predict the required time TMest. Further, for example, the CPU 141 may predict the future temporal change of the temperature difference Y and predict the required time TMest by using a multivariate analysis method based on other data related to the operating state (operation state) of the power conversion device 100 other than the temperature difference Y, the fin temperature Tf, the internal air temperature Ta, and the operating time OT. In this case, at the timing when the temperature difference Y and the like are stored in the RAM 142B (see step S112 in FIG. 4), other data may also be stored in the RAM 142B and may be recorded in the ring buffer RB when the operation of the power conversion device 100 is stopped (see step S206 in FIG. 5). The other data may include, for example, data such as the speed command value of the motor M, the frequency command value of the output power, the output voltage command value, the output current detection value, the operation operation history information, the measurement values of other temperature sensors, and the failure history information.

[0131] When the process of step S414 is completed, the CPU 141 proceeds to step S416.

[0132] In step S416, the CPU 141 determines whether the required time TMest is shorter (smaller) than the reference time TMth (an example of the first reference time). If the required time TMest is shorter than the reference time TMth, the CPU 141 proceeds to step S418. If it is equal to or longer than the reference time TMth, the process of the present flowchart ends.

[0133] In step S418, the CPU 141 issues a clogging alarm for the cooling fins to the user.

[0134] The cooling fin clogging alarm may be reported to the user through the display device 160 as described above, or may be reported to the user through the terminal device 300. Also, on the display device 160, the terminal device 300 (display unit 310), etc., only the fact of the cooling fin clogging alarm may be displayed as described above, or alternatively, data regarding the operating state of the power conversion device 100 may be displayed numerically.

[0135] When the process of step S418 is completed, the CPU 141 proceeds to step S420.

[0136] In step S420, the CPU 141 determines whether the operation time TMfan of the cooling fan 180 is equal to or greater than a reference value TMfan_th. The operation time TMfan of the cooling fan 180 corresponds to the cumulative operation time since the cooling fan 180 was new. The operation time TMfan may be obtained by cumulatively measuring time based on the clock counter of the CPU 141 during its operation time since the power conversion device 100 was shipped from the factory. Also, when the cooling fan 180 is replaced, it may be reset. The reference value TMfan_th is defined in advance as the so-called lifespan or warranty period of the cooling fan 180. If the operation time TMfan of the cooling fan 180 is equal to or greater than the reference value TMfan_th, the CPU 141 proceeds to step S422; if it is less than (shorter than) the reference value TMfan_th, the processing of the current flowchart ends.

[0137] In step S422, the CPU 141 issues an alarm (hereinafter, "fan abnormality alarm") indicating that there may be an abnormality in the cooling fan to the user.

[0138] The fan abnormality alarm may be reported to the user through the display device 160, or may be reported to the user through the terminal device 300, similar to the case of the cooling fin clogging alarm or the like. Further, only the fact of the fan abnormality alarm may be displayed on the display device 160, the terminal device 300 (display unit 310), or the like. Further, data related to the operating state of the power conversion device 100 related to the fan abnormality alarm (for example, the numerical value of the operating time TMfan corresponding to the cumulative operating time of the cooling fan 180, etc.) may also be displayed on the display device 160 and the terminal device 300 (display unit 310).

[0139] When the process of step S422 is completed, the CPU 141 ends the process of this flowchart.

[0140] As described above, in this example, the control device 140 determines the presence or absence of a clogging abnormality in the cooling fin unit 194 based on the increasing tendency of the temperature difference Y. Specifically, the control device 140 predicts the time change of the temperature difference Y based on the history of the past temperature difference Y recorded in the ring buffer RB, and obtains the required time TMest until the temperature difference Y reaches the reference value Yth2. Then, when the required time TMest is shorter than the reference time TMth, that is, when it is determined that the timing at which the power conversion device 100 is forced to stop with the temperature difference Y exceeding the reference value Yth2 is approaching, the control device 140 issues a cooling fin clogging alarm to the user. Thereby, the control device 140 can prompt the user to clean the cooling fin unit 194 or the like at a stage before the power conversion device 100 is forcibly stopped with the temperature difference Y exceeding the reference value Yth2.

[0141] In addition, since the clogging of the cooling fin unit 194 or the like progresses gradually, it may become difficult to adjust between the operation period of a predetermined machine driven by the electric motor M and the maintenance period for cleaning the cooling fin unit 194 or the like.

[0142] On the other hand, in this example, by appropriately adjusting the required time TMest, the control device 140 can notify the user of a cooling fin clogging alarm at a stage prior to the progression of the clogging abnormality to the extent that the power conversion device 100 is forcibly stopped. Therefore, the user can adjust the operation time and maintenance time of a predetermined machine electrically driven by the electric motor M upon receiving the notification of the cooling fin clogging alarm.

[0143] Also, in this example, when the fin temperature Tf is greater than a reference value Tf_th1 that is lower than a reference value Tf_th2 corresponding to the fin temperature Tf when the power conversion device 100 is forcibly stopped, the CPU 141 issues a cooling fin clogging alarm to the user. Thereby, the control device 140 can prompt the user to clean the cooling fin unit 194 or the like at a stage before the fin temperature Tf exceeds the reference value Tf_th2 and the power conversion device 100 is forcibly stopped.

[0144] Also, in this example, when the internal air temperature Ta is greater than a reference value Ta_th1, the CPU 141 issues an internal air abnormality alarm and a cooling fin clogging alarm to the user. Thereby, in a situation where the internal air temperature has deviated from the normal range and has become high, the user can be prompted to perform various maintenance operations including cleaning to eliminate the clogging of the cooling fin unit 194 and suppress the increase in the internal air temperature.

[0145] Subsequently, the flowchart of FIG. 8 is repeatedly executed for each predetermined control cycle during the operation of the power conversion device 100.

[0146] As shown in FIG. 8, in step S502, the CPU 141 determines whether data is recorded in the ring buffer RB, that is, whether a ring buffer flag F2 is set in the RAM 142A. If the ring buffer flag F2 is set, the CPU 141 proceeds to step S504; if not, the processing of this flowchart is terminated.

[0147] In step S504, the CPU 141 determines whether the operation time OT is equal to or greater than a reference time OTth (an example of the second reference time). If the operation time OT is equal to or greater than the reference time OTth, the CPU 141 proceeds to step S506. If it is less than the reference time OTth, the processing of the current flowchart ends.

[0148] In step S506, the CPU 141 determines whether the ring buffer pointer RP is the head pointer RPtop. The head pointer RPtop corresponds to the number of the buffer B in which the oldest data among the buffers B(1) to B(RPmax) of the ring buffer RB is recorded. The initial value of the head pointer RPtop is "1". When data is recorded in all of the buffers B(1) to B(RPmax) and the latest data is recorded in the buffer B(1), the head pointer RPtop moves to "2". Thereafter, each time the latest data is recorded, the head pointer RPtop moves one position forward. If the ring buffer pointer RP is the head pointer RPtop, the CPU 141 proceeds to step S508. If it is not the head pointer RPtop, the CPU 141 proceeds to step S510.

[0149] In step S508, the CPU 141 clears the ring buffer pointer RP and the ring buffer flag F2 of the EEPROM 143B.

[0150] When the processing of step S508 is completed, the CPU 141 proceeds to step S512.

[0151] On the other hand, in step S510, the CPU 141 moves the ring buffer pointer RP back by one. For example, if the ring buffer pointer RP is not 1, the value of the ring buffer pointer RP is decremented by 1 (RP = RP - 1). Also, for example, if the ring buffer pointer RP is "1", the ring buffer pointer RP is set to RPmax (RP = RPmax).

[0152] When the processing of step S510 is completed, the CPU 141 proceeds to step S512.

[0153] In step S512, the CPU 141 clears the operation time OT. As a result, the counting of the operation time OT restarts from zero again.

[0154] When the process of step S512 is completed, the CPU 141 ends the process of the current flowchart.

[0155] As described above, in this example, when a certain amount of time (reference time OTth) has elapsed since the recording of the latest data in the ring buffer RB, the control device 140 moves the ring buffer pointer RP back by one and regards the latest data as non-existent. Thereby, for example, after the acquisition of the latest data, the cooling fin portion 194 or the intake port of the housing of the power conversion device 100 is cleaned, and in a situation where the increasing trend of the temperature difference Y has been eliminated, the latest data is used, and a situation where an incorrect determination of cooling abnormality is made can be suppressed.

[0156] Also, in this example, the control device 140 can retain the data before the latest data in the ring buffer RB. Thereby, for example, even in a situation where the cooling fin portion 194 or the intake port of the housing of the power conversion device 100 has been cleaned but the cleaning is insufficient and the increase in the temperature difference Y starts immediately, not only the newly recorded data but also the remaining data can be used. Therefore, the control device 140 can determine that there is a clogging abnormality in the cooling fin portion 194 at an earlier stage even when, for example, after a simple cleaning is performed and the increase in the temperature difference Y is temporarily eliminated, the increasing trend of the temperature difference Y appears again.

[0157] Also, in this example, after the control device 140 rewinds the ring buffer RB by one, it clears the operation time OT. As a result, the control device 140 can rewind the ring buffer pointer RP one by one each time the reference time OTth elapses while no new data is recorded after the latest data is recorded in the ring buffer RB. Then, when the ring buffer pointer RP returns to the head pointer RPtop and the reference time OTth elapses without new data being recorded even in that state, the ring buffer RB can be regarded as having no data. Therefore, the control device 140 can suppress a situation where old data is used and a false determination of cooling abnormality occurs, for example, in a situation where the increasing tendency of the temperature difference Y is completely eliminated by cleaning the cooling fin portion 194 or the intake port of the housing of the power conversion device 100.

[0158] <Specific Example of Cooling Abnormality Determination Operation> FIG. 9 is a diagram for explaining an example of an operation related to the determination of cooling abnormality by the control device 140. Specifically, FIG. 9 is a diagram showing in time series the data Tf_N1, Tf_N2, Tf_N3, Tf_N4 of the fin temperature Tf and the data Y_N1, Y_N2, Y_N3, Y_N4 of the temperature difference Y recorded in the ring buffer RB by the control device 140. FIG. 9 includes a graph 910 showing the data Tf_N1, Tf_N2, Tf_N3, Tf_N4 of the fin temperature Tf in time series and a graph 920 showing the data Y_N1, Y_N2, Y_N3, Y_N4 of the temperature difference Y in time series.

[0159] Note that the data Tf_N1 and the data Y_N1, the data Tf_N2 and the data Y_N2, the data Tf_N3 and the data Y_N3, and the data Tf_N4 and the data Y_N4 are data recorded in the ring buffer RB at the same timing, respectively. The same applies to the case of FIG. 11 described later.

[0160] As shown in FIG. 9, when the temperature difference Y is equal to or less than the reference value Yth1 (refer to the data Y_NX in the figure), the data is not recorded in the ring buffer RB. On the other hand, when the temperature difference Y exceeds the reference value Yth1, it is determined that there is a sign of clogging abnormality in the cooling fin portion 194, and new data (in this example, data Y_N1, Tf_N1) is recorded in the ring buffer RB (refer to FIG. 4). Then, each time the current temperature difference Y exceeds the maximum value (maximum temperature difference Ymax) of the recorded past temperature differences Y, new data (in this example, data Tf_N2, Y_N2, etc.) is sequentially recorded in the ring buffer RB (refer to FIG. 4). As a result, the ring buffer RB accumulates history data of the temperature difference Y representing the increasing trend of the temperature difference Y.

[0161] In this example, the control device 140 predicts the time change of the temperature difference Y by linear approximation based on the data Y_N1, Y_N2, Y_N3, Y_N4 at the timing after the data Y_N4, Tf_N4 is recorded. Specifically, the control device 140 calculates an approximate straight line L1 of the time change, calculates a required time TMest from the intersection of the approximate straight line L1 and the straight line corresponding to the reference value Yth2, and determines that the calculated required time TMest is shorter than the reference time TMth. Therefore, the control device 140 can issue a cooling fin clogging alarm and prompt the user to clean the cooling fin portion 194 such as clogging.

[0162] Also, before the data Y_N4, Tf_N4 is acquired, the data of the fin temperature Tf (in this example, data Tf_N3a) may exceed the reference value Tf_th1. Even in this case, the control device 140 issues a cooling fin clogging alarm. Therefore, even when the rising trend of the fin temperature Tf is more prominent than the increasing trend of the temperature difference Y, the control device 140 can appropriately make the user aware of the possibility of clogging abnormality in the cooling fin portion 194 and prompt the user to clean the cooling fin portion 194 such as clogging.

[0163] Also, before the data Y_N4,Tf_N4 is acquired, cleaning may be performed on the cooling fin portion 194, the intake port of the housing of the power conversion device 100, etc. For example, if cleaning is performed after the data Y_N2,Tf_N2 is recorded, the increasing tendency of the temperature difference Y is eliminated, and even if the time elapses for more than the reference time OTth, the data Y_N3b cannot exceed the data Y_N2, and no new data is recorded. In this case, the control device 140 moves the ring buffer pointer RP back by one and regards the latest data Y_N2 as non-existent. Therefore, the control device 140 uses the latest data Y_N2 and suppresses a situation where the increasing tendency of the temperature difference Y is misrecognized, and as a result, it is possible to suppress a false determination of a clogging abnormality in the cooling fin portion 194.

[0164] [Another example of the operation related to the determination of cooling abnormality of the power conversion device] Next, with reference to FIGS. 10 and 11, another example of the operation related to the determination of cooling abnormality of the power conversion device 100 will be described.

[0165] Hereinafter, the description will be centered on the parts different from the above example, and the description of the same or corresponding contents may be simplified or omitted.

[0166] [Control process related to determination of cooling abnormality] FIG. 10 is a diagram showing another example of the control process related to the determination of cooling abnormality. Specifically, FIG. 10 is a flowchart schematically showing another example of the data acquisition process related to the determination of cooling abnormality.

[0167] In this example, the end process related to the determination of cooling abnormality, the start process related to the determination of cooling abnormality, the determination process of cooling abnormality, and the determination process of cooling abnormality mitigation are the same as those in the above example (FIGS. 5 to 8), and thus the description will be omitted.

[0168] The flowchart of FIG. 10 is repeatedly executed at a predetermined control cycle during the operation of the power conversion device 100, that is, from the start of operation (power-on of the control device 140) to the stop of operation (power-off of the control device 140), similar to the above example (in the case of FIG. 4).

[0169] As shown in FIG. 10, since the processes of steps S602 and S604 are the same as those of steps S102 and S104 in FIG. 4, the description thereof is omitted.

[0170] When the process of step S604 is completed, the CPU 141 proceeds to step S606.

[0171] In step S606, the CPU 141 determines whether data is recorded in the ring buffer RB, that is, whether the ring buffer flag F2 is set in the RAM 142B. When the ring buffer flag F2 is not set, the CPU 141 proceeds to step S608, and when the ring buffer flag F2 is set, the CPU 141 proceeds to step S610.

[0172] In step S608, the CPU 141 determines whether the temperature difference Y is greater than a reference value Yth0 (<Yth1) (an example of the third reference value) and less than or equal to the reference value Yth1. When the temperature difference Y is greater than the reference value Yth0 and less than or equal to the reference value Yth1, the CPU 141 proceeds to step S616, and in other cases, the current flowchart ends.

[0173] On the other hand, since the processes of steps S610 to S614 are the same as those of steps S106 to S110 in FIG. 4, the description thereof is omitted.

[0174] When the process of step S614 is completed, the CPU 141 proceeds to step S616.

[0175] Since the processes of steps S616 and S618 are the same as those of steps S112 and S114 in FIG. 4, the description thereof is omitted.

[0176] When the process of step S618 is completed, the CPU 141 ends the process of the current flowchart.

[0177] As described above, in this example, when there is no data recorded in the ring buffer RB, the control device 140 records, as the first data, the temperature difference Y when the temperature difference Y is greater than the reference value Yth0 (<Yth1) and less than or equal to the reference value Yth1, etc., in the ring buffer RB. Then, the control device 140 cumulatively records the data including the temperature difference Y exceeding the reference value Yth1 in the ring buffer RB. Thereby, it is possible to suppress a situation in which data of a situation where the temperature difference Y suddenly exceeds the reference value Yth1 for some reason different from the clogging of the cooling fin portion 194 is acquired, and an incorrect determination of the clogging abnormality of the cooling fin portion 194 is made. The progress of the clogging abnormality of the cooling fin portion 194 is relatively slow, and it is less likely that data in the range exceeding the reference value Yth1 is first acquired without the data in the range where the temperature difference Y is greater than the reference value Yth0 and less than or equal to the reference value Yth1 being acquired.

[0178] <Specific Example of Cooling Abnormality Determination Operation> FIG. 11 is a diagram for explaining another example of the operation related to the determination of cooling abnormality by the control device 140. Specifically, FIG. 11 is a diagram showing, in time series, the data Tf_N0, Tf_N1, Tf_N2, Tf_N3, Tf_N4 of the fin temperature Tf and the data Y_N0, Y_N1, Y_N2, Y_N3, Y_N4 of the temperature difference Y recorded in the ring buffer RB by the control device 140. FIG. 11 includes a graph 1110 showing, in time series, the data Tf_N0, Tf_N1, Tf_N2, Tf_N3, Tf_N4 of the fin temperature Tf and a graph 1120 showing, in time series, the data Y_N0, Y_N1, Y_N2, Y_N3, Y_N4 of the temperature difference Y.

[0179] FIG. 11 is the same as the case of the above example (FIG. 9) except that the data Tf_N0 and Y_N0 are added. Hereinafter, the description will focus on the parts different from the above example (FIG. 9).

[0180] Note that the data Tf_N0 and the data Y_N0 are data recorded in the ring buffer RB at the same timing, respectively.

[0181] As shown in FIG. 11, in this example, different from the above example (FIG. 9), when the temperature difference Y is larger than the reference value Yth0 and equal to or less than the reference value Yth1, the data Y_N0, Tf_N0 in this range are first recorded in the ring buffer RB. Then, afterwards, the data Y_N1, Tf_N1 with the temperature difference Y exceeding the reference value Yth1 are recorded in the ring buffer RB. Thereby, for example, it is possible to prevent data in a situation where the temperature difference Y suddenly increases due to some reason other than the clogging abnormality of the cooling fin portion 194 and the temperature difference Y exceeds the reference value Yth1 from being recorded in the ring buffer RB. Therefore, the control device 140 can suppress an incorrect determination of the clogging abnormality of the cooling fin portion 194 caused by the use of such data.

[0182] [Another example of the operation related to the determination of the cooling abnormality of the power conversion device] Next, with reference to FIG. 12, another example of the operation related to the determination of the cooling abnormality of the power conversion device 100 will be described.

[0183] Hereinafter, the description will focus on the parts different from the above examples, etc., and the description of the same or corresponding contents may be simplified or omitted.

[0184] FIG. 12 is a diagram showing still another example of the control process related to the determination of the cooling abnormality. Specifically, FIG. 12 is a flowchart schematically showing another example of the cooling abnormality determination process.

[0185] In the above examples, etc., the control device 140 determines the presence or absence of the cooling abnormality of the power conversion device 100 based on the time change in which the temperature difference Y increases. However, the presence or absence of the cooling abnormality of the power conversion device 100 may be determined more simply based on the temperature difference Y. Specifically, when the temperature difference Y is relatively high (for example, when the temperature difference Y exceeds a predetermined reference value set between the reference value Yth1 or the reference value Yth1 and the reference value Yth2), the control device 140 may determine that there is a cooling abnormality in the cooling fin portion 194. The following will specifically describe.

[0186] As shown in FIG. 12, since steps S702 and S704 are the same as the processes of steps S102 and S104 in FIG. 4, the description thereof is omitted.

[0187] When the process of step S704 is completed, the control device 140 proceeds to step S706.

[0188] In step S706, the CPU 141 determines whether the temperature difference Y calculated in step S104 exceeds the reference value Yth1. When the temperature difference Y exceeds the reference value Yth1, the CPU 141 determines that there is an abnormality in the cooling structure unit 190 (cooling fin unit 194), and proceeds to step S708. When the temperature difference Y does not exceed the reference value Yth1, the processing of the current flowchart is terminated.

[0189] In step S708, the CPU 141 issues a clogging alarm for the cooling fins to the user.

[0190] When the process of step S708 is completed, the control device 140 terminates the processing of the current flowchart.

[0191] Note that in this example, the control process for determining cooling abnormalities is aggregated in the flowchart of FIG. 12, and data acquisition processes, end processes, start-up processes, etc. related to determining cooling abnormalities in the above examples are not set. Therefore, in this example, the EEPROM 143B and the ring buffer RB may be omitted.

[0192] As described above, in this example, the control device 140 can determine that there is a cooling abnormality in the cooling structure unit 190 (cooling fin unit 194) triggered only by the relatively high temperature difference Y. Therefore, the control device 140 can determine a cooling abnormality in the cooling structure unit 190 with a relatively simple configuration.

[0193] [Other Embodiments] Next, other embodiments will be described.

[0194] The content of the above-described embodiments may be appropriately modified or changed.

[0195] Also, for example, in the above-described embodiment, the control device 140 may extract a singular value from the data of the temperature difference Y recorded in the ring buffer RB. Then, the control device 140 may perform a determination regarding cooling abnormality based on the data of the temperature difference Y other than the singular value among the data of the temperature difference Y recorded in the ring buffer RB. Thereby, the control device 140 can improve the accuracy of the determination regarding cooling abnormality and perform the determination regarding cooling abnormality more appropriately. Specifically, when approximating and predicting the time change (required time TMest) of the temperature difference Y (see step S414 in FIG. 7), the control device 140 may use only the data of the temperature difference Y other than the singular value. Thereby, the control device 140 can improve the prediction accuracy of the required time TMest.

[0196] Also, for example, in the above-described embodiment (FIG. 8), when a time equal to or longer than the reference time OTth has elapsed since the latest data was recorded in the ring buffer RB, the ring buffer pointer RP is moved back by one, and at the same time, B(RP) of the ring buffer RB may be erased.

[0197] Also, for example, in the above-described embodiment, the power conversion device 100 (control device 140) may manually erase all the data in the ring buffer RB in response to an input received from the user. Thereby, the user can erase the data in the ring buffer RB by himself / herself, for example, when cleaning the cooling fin portion 194 or the intake port of the housing of the power conversion device 100. In this case, an input from the user may be received through an input unit provided in a predetermined machine electrically driven by the power conversion device 100 or the electric motor M, or an input from the user may be received through the terminal device 300 communicably connected to the power conversion device 100.

[0198] Further, for example, in the above-described embodiment, the power conversion device 100 (control device 140) may be configured such that when the possibility of cooling abnormality is eliminated, all the data in the ring buffer RB is automatically erased. For example, when the operation time OT exceeds a predetermined threshold while the control device 140 operates without new data being recorded after the latest data is recorded in the ring buffer RB, the control device 140 may determine that the cleaning of the cooling fin portion 194 has been performed and the possibility of cooling abnormality has been eliminated. The predetermined threshold may be defined in advance within a range of, for example, a reference time OTth or more. Further, for example, when the temperature difference Y continuously remains below or equal to a reference value Yth1 between the start (power on) and stop (power off) of the current operation of the power conversion device 100, the control device 140 may determine that the possibility of cooling abnormality has been eliminated. In this case, the control device 140 may erase all the data in the ring buffer RB when it determines that the possibility of cooling abnormality has been eliminated (i.e., when the power conversion device 100 stops operating), or at the start of the next operation.

[0199] Also, for example, in the above-described embodiment, data used for determining cooling abnormality, including the temperature difference Y and the operation time OT, is recorded inside the power conversion device 100, but it may be recorded in an external device of the power conversion device 100. The external device may be, for example, an arithmetic device 200 or a terminal device 300 (both are examples of a third external device). In this case, the control device 140 transmits and accumulates data regarding the temperature difference Y and data regarding the operation pattern of the power conversion device 100 to the external device. The data regarding the operation pattern of the power conversion device 100 may include, for example, data representing the timing of operation start and stop, and data regarding the communication timing of the semiconductor diode SD and the semiconductor switch SW. Then, the control device 140 may download and use the accumulated data from the external device to determine the presence or absence of cooling abnormality in the same manner as described above.

[0200] Further, for example, in the above-described embodiment, part or all of the functions of the control device 140 may be transferred to an external device of the power conversion device 100, such as an arithmetic device 200 or a terminal device 300 (both are examples of a cooling abnormality determination device).

[0201] [Operation] Next, the operation of the power conversion device 100 (control device 140) according to the present embodiment will be described.

[0202] In the present embodiment, the power conversion device 100 includes a power device, a cooling structure unit 190, a cooling fan 180, and a control device 140. Specifically, the power device includes a semiconductor diode SD and a semiconductor switch SW. Further, the cooling structure unit 190 is provided for heat dissipation of the power device. Further, the cooling fan 180 blows air to the cooling structure unit 190. And the control device 140 determines an abnormality in the cooling performance by the cooling structure unit 190 based on the temperature difference Y between the temperature (fin temperature Tf) of the cooling structure unit 190 (cooling fin unit 194) and the temperature (internal air temperature Ta) inside the power conversion device 100 (housing).

[0203] Thereby, the control device 140 can appropriately determine the presence or absence of a cooling abnormality in the cooling structure unit 190 by paying attention to the fact that the temperature difference Y becomes relatively large due to clogging or the like of the cooling fin unit 194.

[0204] Also, for example, as in the above-mentioned Patent Document 1, it is also possible to determine a cooling abnormality using the temperature itself at a predetermined location of the power conversion device 100. However, since there is a possibility that the influence due to the fluctuation of the load state of the power conversion device is superimposed on the change in the measured temperature, the accuracy of determining a cooling abnormality by the cooling fins may decrease.

[0205] On the other hand, in the present embodiment, the control device 140 suppresses the influence of the load state of the power conversion device 100 by using the difference (temperature difference Y) between the temperatures at two locations inside the power conversion device 100 instead of the temperature itself at a predetermined location of the power conversion device 100, and can more appropriately determine an abnormality related to cooling.

[0206] Also, for example, as in Patent Document 2 described above, in addition to the temperature of the cooling fins and the temperature inside the power conversion device, it is also possible to determine a cooling abnormality using the load state of the power conversion device. In this case, considering the load state of the power conversion device, an improvement in the determination accuracy can be expected. However, in the method of individually using the temperature of the cooling fins and the temperature inside the power conversion device, as in Patent Document 2, it is necessary to assume the occurrence of a heating abnormality such that the power conversion device is forced to stop. As described above, the progress of clogging abnormality of the cooling fins and the like is relatively slow, and even when considering the influence of the load state of the power conversion device, it is difficult to capture the tendency of the cooling abnormality by individually using the temperature of the cooling fins and the temperature inside the power conversion device.

[0207] In contrast, in the present embodiment, the control device 140 can more appropriately (earlier) determine a cooling abnormality before reaching a state where it is necessary to force the power conversion device 100 to stop, for example, by capturing a phenomenon in which the temperature difference Y becomes relatively large.

[0208] Also, in the present embodiment, the control device 140 may determine a cooling abnormality based on the time change in which the temperature difference Y increases.

[0209] Thereby, the control device 140 can suppress, for example, the concern of misjudgment regarding a cooling abnormality caused by the cooling structure unit 190 in a situation where the temperature difference Y becomes relatively large for reasons different from those of the cooling structure unit 190.

[0210] Also, in the present embodiment, the control device 140 may determine that there is a cooling abnormality when the temperature difference Y exceeds a reference value Yth1.

[0211] Thereby, by appropriately setting the reference value Yth1, the control device 140 can specifically determine the presence or absence of a cooling abnormality caused by the cooling structure unit 190.

[0212] Further, in the present embodiment, the control device 140 may correct the measured value of the temperature difference Y to the temperature difference Y when the power device is in a predetermined load state, and determine the presence or absence of cooling abnormality based on the corrected temperature difference Y.

[0213] Thereby, the control device 140 can suppress the influence of the load state of the power device on the temperature difference Y, and can more appropriately determine the cooling abnormality related to the cooling structure unit 190.

[0214] Further, in the present embodiment, the control device 140 may correct the measured value of the temperature difference Y to the temperature difference Y when the power device is in a predetermined load state based on the temperature of the power device (for example, the measured value of the junction temperature Tj).

[0215] Thereby, the control device 140 can specifically suppress the influence of the load state of the power device on the temperature difference Y.

[0216] Further, in the present embodiment, the control device 140 may correct the measured value of the temperature difference Y to the temperature difference Y when the power device is in a predetermined load state based on the load current IL (measured value) output by the power conversion device 100.

[0217] Thereby, the control device 140 can specifically suppress the influence of the load state of the power device on the temperature difference Y.

[0218] Further, in the present embodiment, the EEPROM 143B is provided. Specifically, when the maximum value of the temperature difference Y (maximum temperature difference Ymax) up to the previous time is updated during the operation of the power conversion device 100 this time, the EEPROM 143B may store the maximum value of the temperature difference Y during the operation of the power conversion device 100 this time when the power conversion device 100 stops operating (when the power is turned off). Then, the control device 140 acquires the maximum value of the temperature difference Y up to the previous operation stop time from the EEPROM 143B at the start of the operation of the power conversion device 100, and grasps the time change of the increase in the temperature difference Y by comparing the temperature difference Y during the operation of the power conversion device 100 with the acquired maximum value of the temperature difference Y (maximum temperature difference Ymax).

[0219] As a result, the control device 140 can specifically grasp the increasing tendency of the temperature difference Y.

[0220] Also, in the present embodiment, when a temperature difference Y exceeding the maximum value (maximum temperature difference Ymax) of the temperature difference Y until the previous operation stop occurs between the start and stop of the operation of the power conversion device 100, the EEPROM 143B may cumulatively store the maximum value of the temperature difference Y between the start and stop of the current operation at the time of the operation stop of the power conversion device 100. Further, the control device 140 may predict the required time (required time TMest) until the temperature difference Y reaches the reference value Yth2 based on the update history of the maximum value of the temperature difference Y stored in the EEPROM 143B (ring buffer RB). Then, when the required time TMest is shorter than the reference time TMth, the control device 140 may determine that there is a cooling abnormality.

[0221] As a result, the control device 140 can specifically determine the presence or absence of a cooling abnormality based on the increasing tendency of the temperature difference Y.

[0222] Also, in the present embodiment, in addition to the update history of the maximum value of the temperature difference Y stored in the EEPROM 143B, the control device 140 may predict the required time TMest using multivariate analysis based on other information regarding the operation state of the power conversion device 100.

[0223] As a result, the control device 140 can improve the prediction accuracy of the required time TMest.

[0224] Also, in the present embodiment, the control device 140 may extract an outlier from the update history of the maximum value of the temperature difference Y stored in the EEPROM 143B, and predict the required time TMest based on the update history of the maximum value of the temperature difference Y other than the outlier.

[0225] As a result, the control device 140 can improve the prediction accuracy of the required time TMest.

[0226] Further, in the present embodiment, the control device 140 may predict the required time TMest in consideration of only the time during which the power device is energized out of the operation time of the power conversion device 100.

[0227] Thereby, the control device 140 can improve the prediction accuracy of the required time TMest.

[0228] Further, in the present embodiment, after the maximum value of the latest temperature difference Y is stored in the EEPROM 143B (ring buffer RB), every time the reference time OTth elapses in a state where the maximum value of the new temperature difference Y is not stored, the maximum value of the temperature difference Y stored in the EEPROM 143B may be made overwritable in order from the newer one of the (update) histories, or may be erased.

[0229] Thereby, the control device 140 can, for example, make the latest temperature difference Y data unavailable in a situation where the cooling fins 194 are cleaned and the increasing trend of the temperature difference Y is eliminated. Therefore, the control device 140 can suppress a situation where the latest temperature difference Y data is used and a misjudgment regarding a cooling abnormality is made. Further, since the control device 140 makes the temperature difference Y data unavailable one by one, the degree of cleaning is simple, and when the increasing trend of the temperature difference Y occurs again, the remaining data can be used to appropriately determine a cooling abnormality.

[0230] Further, in the present embodiment, the control device 140 may determine the elapse of the reference time OTth in consideration of only the time during which the power device is energized out of the operation time of the power conversion device 100.

[0231] Thereby, the control device 140 can more appropriately determine whether or not the increasing trend of the temperature difference Y has been eliminated.

[0232] Further, in the present embodiment, the EEPROM 143B may store the maximum value of the temperature difference Y when the temperature difference Y exceeds the reference value Yth1.

[0233] As a result, the EEPROM 143B can store only the data of the temperature difference Y (maximum value) corresponding to a level indicating that the degree of cooling abnormality is at a certain high level.

[0234] Also, in the present embodiment, the EEPROM 143B may store the temperature difference Y (history of the maximum value) when the temperature difference Y exceeds a reference value Yth0 smaller than the reference value Yth1. Then, when a temperature difference Y (history of the maximum value) greater than the reference value Yth1 is stored in the EEPROM 143B and a temperature difference Y (history of the maximum value) equal to or less than the reference value Yth1 stored previously is also stored, the control device 140 may determine that there is an abnormality.

[0235] As a result, the control device 140 can suppress a situation where, for example, in a situation where the temperature difference Y has risen rapidly for a reason different from the cooling abnormality of the cooling structure unit 190, it is erroneously determined that there is a cooling abnormality in the cooling structure unit 190.

[0236] Also, in the present embodiment, under the control of the control device 140, when the possibility of an abnormality occurring is eliminated, the EEPROM 143B may automatically or manually erase all the temperature differences Y (update history of the maximum value) stored in the ring buffer RB in response to a received predetermined input.

[0237] As a result, in a situation where the cooling fins 194 are cleaned and the increasing tendency of the temperature difference Y has been completely eliminated, the control device 140 can automatically or manually erase the data of the temperature difference Y (history of the maximum value) in the ring buffer RB.

[0238] Also, in the present embodiment, the reference value Yth1 may be defined based on the temperature difference Y when the cooling performance by the cooling structure unit 190 is in a predetermined normal state and the temperature difference Y when the cooling fan 180 is stopped.

[0239] As a result, the control device 140 can specifically define the reference value Yth1 for determining regarding the cooling abnormality.

[0240] Further, in the present embodiment, the power conversion device 100 may include a display device 160 and a communication device 170 that, when an abnormality is determined by the control device 140, notify the user of the abnormality.

[0241] Thereby, the power conversion device 100 can notify the user of a cooling abnormality through the display device 160 and the communication device 170.

[0242] Further, in the present embodiment, the power conversion device 100 (control device 140) may transmit data related to the operating state of the power conversion device 100 including data related to a cooling abnormality to the terminal device 300 and cause it to be displayed on the display unit 310 of the terminal device 300.

[0243] Thereby, the power conversion device 100 can provide information regarding a cooling abnormality to the user through an external terminal device 300.

[0244] Further, in the present embodiment, the power conversion device 100 may include a display device 160 that displays information related to the operating state of the power conversion device 100 including information related to a cooling abnormality.

[0245] Thereby, the power conversion device 100 can visually provide information regarding a cooling abnormality to the user through the display device 160.

[0246] Further, in the present embodiment, the power conversion device 100 (control device 140) may cause the display device 160 to display information related to a cooling abnormality as a numerical value.

[0247] Thereby, the power conversion device 100 (control device 140) can more appropriately provide information regarding a cooling abnormality to the user.

[0248] Further, in the present embodiment, the power conversion device 100 (control device 140) may cause the arithmetic device 200 to execute arithmetic processing related to the determination of a cooling abnormality.

[0249] As a result, the power conversion device 100 (control device 140) can reduce the processing load related to the determination of cooling abnormality, and for example, can suppress a situation where the processing related to the determination of cooling abnormality affects the control processing of the inverter circuit 130 or the like.

[0250] Also, in the present embodiment, the control device 140 may store data related to the temperature difference Y and data related to the operation pattern of the power conversion device 100 in the arithmetic device 200, the terminal device 300, or the like. Then, the control device 140 may perform a determination related to cooling abnormality based on the data stored in the arithmetic device 200, the terminal device 300, or the like.

[0251] As a result, the control device 140 can cause an external device to perform the process of accumulating data only by appropriately uploading the data for determining cooling abnormality.

[0252] Although the embodiments have been described in detail above, the present disclosure is not limited to such specific embodiments, and various modifications and changes are possible within the scope of the gist described in the claims.

Explanation of Reference Numerals

[0253] 1 Cooling abnormality determination system 100 Power conversion device 110 Rectifier circuit 110A Circuit board 120 Smoothing circuit 130 Inverter circuit 130A Circuit board 140 Control device (determination unit, cooling abnormality determination device) 141 CPU 142 Memory device 142A, 142B RAM 143 Auxiliary storage device 143A ROM 143B EEPROM (storage unit) 144 Interface 150 Sensor 160 Display device (notification unit, display unit) 170 Communication device (notification unit) 180 Cooling fan (air blowing unit) 190 Cooling structure unit 192 Fin base 194 Cooling fin unit 194A Fin 200 Arithmetic unit (second external device, third external device, cooling abnormality determination device) 300 Terminal device (first external device, third external device, cooling abnormality determination device) 310 Display unit M Electric motor PS Commercial power supply RB Ring buffer SD Semiconductor diode (power device) SW Semiconductor switch (power device)

Claims

1. A power device, a cooling structure for dissipating heat of the power device, a blower for blowing air to the cooling structure, and a determination unit that determines an abnormality based on the fact that the degree of abnormality of the cooling performance by the cooling structure becomes higher as the temperature difference between the temperature of the cooling structure and the temperature of the air inside the power conversion device increases. The determination unit corrects the measured value of the temperature difference to the temperature difference when the power device is in a predetermined load state, determines the abnormality based on the corrected temperature difference, and determines that there is an abnormality when the temperature difference exceeds a predetermined first reference value. A power conversion device.

2. The determination unit determines the abnormality based on the time change in which the temperature difference increases. The power conversion device according to claim 1.

3. The determination unit corrects the measured value of the temperature difference to the temperature difference when the power device is in the predetermined load state based on the temperature of the power device. The power conversion device according to claim 1 or 2.

4. The determination unit corrects the measured value of the temperature difference to the temperature difference when the power device is in the predetermined load state based on the load current output by the power conversion device. The power conversion device according to claim 1 or 2.

5. Comprising a non-volatile storage unit, when the maximum value of the temperature difference up to the previous time is updated during the operation of the current power conversion device, the storage unit stores the maximum value of the temperature difference during the operation of the current power conversion device when the power of the power conversion device is turned off. The determination unit acquires the maximum value of the temperature difference from the previous operation stop to the start of the operation of the power conversion device from the storage unit, and grasps the time change of the increase in the temperature difference by comparing the temperature difference during the operation of the power conversion device with the acquired maximum value of the temperature difference. The power conversion device according to claim 2.

6. When a temperature difference exceeding the maximum value of the temperature difference up to the previous power-off occurs between the power-on and power-off of the power conversion device, the storage unit cumulatively stores the maximum value of the temperature difference between the current power-on and power-off when the power of the power conversion device is turned off. The determination unit predicts the required time until the temperature difference reaches a predetermined second reference value based on the update history of the maximum value of the temperature difference stored in the storage unit, and determines that there is an abnormality when the predicted required time is shorter than a predetermined first reference time. The power conversion device according to claim 5.

7. In addition to the update history of the maximum value of the temperature difference stored in the storage unit, the determination unit predicts the required time using multivariate analysis based on other information related to the operating state of the power conversion device. The power conversion device according to claim 6.

8. The determination unit extracts an outlier from the update history of the maximum value of the temperature difference stored in the storage unit, and predicts the required time based on the update history of the maximum value of the temperature difference other than the outlier. The power conversion device according to claim 6 or 7.

9. The determination unit predicts the required time in consideration of only the time during which the power device is energized among the operating time of the power conversion device. The power conversion device according to any one of claims 6 to 8.

10. Every time a predetermined second reference time elapses in a state where a new maximum value of the temperature difference is not stored since the latest maximum value of the temperature difference is stored in the storage unit, the history of the maximum value of the temperature difference stored in the storage unit is made overwriteable or erased in order from the newer one. The power conversion device according to any one of claims 6 to 9.

11. The determination unit determines the elapse of the second reference time in consideration of only the time during which the power device is energized among the operating time of the power conversion device. The power conversion device according to claim 10.

12. When the temperature difference exceeds the first reference value, the storage unit stores the maximum value of the temperature difference. The power conversion device according to any one of claims 5 to 11.

13. When the temperature difference exceeds a predetermined third reference value smaller than the first reference value, the storage unit stores the maximum value of the temperature difference. When the maximum value of the temperature difference greater than the first reference value is stored in the storage unit and the maximum value of the temperature difference less than or equal to the first reference value stored before that is stored, the determination unit determines that there is an abnormality. The power conversion device according to claim 12.

14. When the possibility of the occurrence of the abnormality is eliminated, the storage unit automatically or manually erases all the maximum values of the temperature difference stored in response to a predetermined input received. The power conversion device according to any one of claims 5 to 13.

15. The first reference value is defined based on the temperature difference when the cooling performance is in a predetermined normal state and the temperature difference when the blower unit is stopped. The power conversion device according to any one of claims 1 to 14.

16. Comprising a notification unit that, when the determination unit determines that there is the abnormality, notifies the user of the abnormality. The power conversion device according to any one of claims 1 to 15.

17. Transmitting data on the operating state of the power conversion device including data on the abnormality to a first external device and causing the data to be displayed on a display unit of the first external device. The power conversion device according to any one of claims 1 to 16.

18. Comprising a display unit that displays information on the operating state of the power conversion device including information on the abnormality. The power conversion device according to any one of claims 1 to 17.

19. Causing the information on the abnormality to be displayed as a numerical value on the display unit. The power conversion device according to claim 17 or 18.

20. Causing a second external device to execute arithmetic processing related to the determination of the abnormality. The power conversion device according to any one of claims 1 to 19.

21. The determination unit accumulates data on the temperature difference and data on the operation pattern of the power conversion device in a third external device, and makes a determination regarding the abnormality based on the data accumulated in the third external device. The power conversion device according to any one of claims 1 to 20.

22. Regarding a power conversion device including a power device, a cooling structure unit for radiating heat of the power device, and a blower unit for blowing air to the cooling structure unit, based on the fact that the degree of abnormality of the cooling performance by the cooling structure unit increases as the temperature difference between the temperature of the cooling structure unit and the temperature of the air inside the power conversion device increases, a cooling abnormality determination device that makes a determination regarding the abnormality, Correcting the measured value of the temperature difference to the temperature difference when the power device is in a predetermined load state, making a determination regarding the abnormality based on the corrected temperature difference, and determining that there is the abnormality when the temperature difference exceeds a predetermined first reference value. Cooling abnormality determination device.

23. Regarding a power conversion device including a power device, a cooling structure unit for radiating heat of the power device, and a blower unit for blowing air to the cooling structure unit, based on the fact that the degree of abnormality of the cooling performance by the cooling structure unit increases as the temperature difference between the temperature of the cooling structure unit and the temperature of the air inside the power conversion device increases, a cooling abnormality determination method that makes a determination regarding the abnormality, The measured value of the temperature difference is corrected to the temperature difference when the power device is in a predetermined load state, and based on the corrected temperature difference, determination regarding the abnormality is performed, and when the temperature difference exceeds a predetermined first reference value, it is determined that there is the abnormality. Cooling abnormality determination method.

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