Power conversion device, deterioration detection system, and ground device

Abstract

This power conversion device (1) comprises: a component state detection unit (24) that detects, as a component state, a physical quantity representing the electrical characteristics of a component provided in the power conversion device (1); a storage unit (21) that stores first component state data, which represents a component state of the host power conversion device (1), and second component state data, which represents a component state of another power conversion device (1) and is transmitted from the other power conversion device (1) over a communication network (8) in a train, and stores a first deterioration curve created by using the first component state data and a second deterioration curve created by using the first and second pieces of component state data; a correction unit (22) that uses the second deterioration curve to correct the first deterioration curve; and a deterioration state detection unit (23) that uses the corrected first deterioration curve to detect a deterioration state of a component.

Description

Power conversion device, deterioration detection system, and ground device

[0001] The present disclosure relates to a power conversion device, a deterioration detection system, and a ground device used in a train consisting of a plurality of railway cars.

[0002] Various electrical devices are installed and operated on trains. Among the electrical devices, power conversion devices used for train propulsion control are electrical devices whose failure can have a significant social impact.

[0003] Generally, there are three types of failures in electrical equipment: initial failures, random failures, and wear-out failures, depending on the period of time during which the failures occur. Of these, initial failures are caused by manufacturing defects, and the rate of failures can be reduced significantly by properly managing quality during manufacturing.

[0004] Patent Document 1 listed below discloses a technique for acquiring status-related values, which are values ​​related to the operating status of a motor system, in a plurality of motor systems, comparing the acquired status-related values ​​between the plurality of motor systems, and diagnosing that an abnormality has occurred if the difference in the status-related values ​​is greater than a threshold value. The technique in Patent Document 1 is considered to be effective for detecting an abnormality due to a random failure in which there is a large difference in the status-related values ​​between a motor system in which an abnormality has occurred and a motor system in which an abnormality has not occurred.

[0005] International Publication No. 2021 / 166839

[0006] In the past, power conversion equipment was maintained using a maintenance method called Time Based Maintenance (TBM), which replaces parts after a specific period of time has elapsed. However, recently, there has been a shift to a maintenance method called Condition Based Maintenance (CBM), which determines whether to replace parts based on data collected from electrical equipment. The key to adopting CBM is the ability to accurately detect abnormalities during the wear-out failure period.

[0007] As mentioned above, the technology of Patent Document 1 is effective for detecting abnormalities during the random failure period. However, during the wear-out failure period, wear-out failures progress in all of the multiple systems, and the differences in the status-related values ​​between the multiple systems are expected to be small. For this reason, it is considered difficult to accurately detect abnormalities during the wear-out failure period using the technology of Patent Document 1.

[0008] The present disclosure has been made in view of the above, and aims to provide a power conversion device that can accurately detect abnormalities in the device even during the wear-out failure period.

[0009] To solve the above-mentioned problems and achieve the object, a power conversion device according to the present disclosure is used in a train consisting of a plurality of railway cars. The power conversion device includes a component state detection unit, a memory unit, a correction unit, and a deterioration state detection unit. The component state detection unit detects physical quantities representing electrical characteristics of components included in the power conversion device as component states. The memory unit stores first component state data representing component states of its own power conversion device and second component state data representing component states of other power conversion devices transmitted from the other power conversion devices via an in-train communication network. The memory unit also stores a first deterioration curve created using the first component state data and a second deterioration curve created using the first and second component state data. The correction unit corrects the first deterioration curve using the second deterioration curve. The deterioration state detection unit detects the deterioration states of the components using the corrected first deterioration curve.

[0010] The power conversion device according to the present disclosure has the advantage of being able to accurately detect abnormalities in the device even during the wear-out failure period.

[0011] 1 is a diagram showing a configuration example of a power conversion device according to embodiment 1; FIG. 2 is a diagram showing a configuration example of a control device provided in the power conversion device according to embodiment 1; FIG. 3 is a diagram serving to explain a power conversion main circuit provided in the power conversion device according to embodiment 1; FIG. 4 is a diagram showing a schematic internal structure of a general power semiconductor module; FIG. 5 is a diagram serving to explain a component state detection unit provided in the control device according to embodiment 1; FIG. 6 is a diagram showing test results when thermal stress is applied to three power semiconductor modules of the same type;

[0012] A power conversion device, a deterioration detection system, and a ground device according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. In the following description, multiple devices and components of the same type will be designated by reference numerals with subscripts, but when describing the devices without distinguishing between them, the subscripts will be omitted as appropriate. In the following embodiments, a power conversion device for train propulsion control will be described as an example, but this does not mean that application to other uses will be excluded. The power conversion device according to the embodiments can also be applied to power conversion devices other than those for propulsion control, such as auxiliary power sources for supplying power to lighting, air conditioning, and the like of railway vehicles.

[0013] First Embodiment. FIG. 1 is a diagram showing an example of the configuration of a power conversion device according to a first embodiment. FIG. 1 shows four power conversion devices 1a to 1d mounted on railway cars that constitute a train. The power conversion devices 1a to 1d are each equipped with a control device 2a to 2d. The power conversion devices 1a to 1d are connected to a communication network 8 so that the control devices 2a to 2d can share data with each other. The communication network 8 is one means of data transmission and is not limited to a wired system. Furthermore, while FIG. 1 shows four power conversion devices 1a to 1d as an example, the present invention is not limited to this example. In other words, the number of power conversion devices 1 may be two or three, or may be five or more.

[0014] Fig. 2 is a diagram showing an example of the configuration of a control device provided in the power conversion device according to embodiment 1. As shown in Fig. 2, the control device 2 includes a storage unit 21, a correction unit 22, a deterioration state detection unit 23, and a component state detection unit 24. Details of the functions of these units will be described later.

[0015] The correction unit 22, the deterioration state detection unit 23, and the component state detection unit 24 can be realized by a processing circuit having a processor and a memory. Alternatively, the correction unit 22, the deterioration state detection unit 23, and the component state detection unit 24 may be realized by a dedicated processing circuit instead of a processor and a memory. Examples of the dedicated processing circuit include a field programmable gate array (FPGA), an application specific integrated circuit (ASIC), and a microcomputer. The storage unit 21 can be realized by a non-volatile or volatile semiconductor memory such as a random access memory (RAM), a flash memory, an erasable programmable read only memory (EPROM), or an electrically programmable read only memory (EEPROM) (registered trademark), or a magnetic disk, an optical disk, or a digital versatile disk (DVD).

[0016] FIG. 3 is a diagram illustrating a power conversion main circuit provided in the power conversion device according to the first embodiment. FIG. 3 shows an example configuration of a power conversion main circuit 150 mounted on a railway vehicle 100. In FIG. 3, the power conversion main circuit 150 includes a converter 110, a filter capacitor 120, and a three-phase inverter 130. The railway vehicle 100 includes a current collector 102, wheels 103, a transformer 106, and a traction motor 140. The transformer 106 is disposed on the input side of the power conversion main circuit 150 and connected to the converter 110. The traction motor 140 is disposed on the output side of the power conversion main circuit 150 and connected to the three-phase inverter 130. The three-phase inverter 130 converts DC power into AC power for the traction motor 140. An induction motor or a synchronous motor is used as the traction motor 140.

[0017] One end of the primary winding of the transformer 106 is electrically connected to the overhead line 101 via the current collector 102, and the other end is electrically connected to the rail 104, which is at ground potential, via the wheels 103. The AC power supplied from the overhead line 101 is input to the converter 110 via the current collector 102 and the transformer 106.

[0018] The converter 110 includes four switching elements UPC, VPC, UNC, and VNC that are connected in a single-phase bridge. The switching elements UPC, VPC, UNC, and VNC are PWM (Pulse Width Modulation) controlled, so that the converter 110 converts the input AC voltage into a desired DC voltage and outputs it.

[0019] A filter capacitor 120, which serves as a DC power supply, is connected in parallel to the output terminal of the converter 110. The filter capacitor 120 smoothes the DC voltage input from the converter 110. A three-phase inverter 130 is connected to the output side of the filter capacitor 120.

[0020] The three-phase inverter 130 includes switching elements UPI, VPI, WPI, UNI, VNI, and WNI that are connected in a three-phase bridge. The three-phase inverter 130 converts the capacitor voltage smoothed by the filter capacitor 120 into a desired AC voltage and applies it to the traction motor 140 by PWM-controlling the switching elements UPI, VPI, WPI, UNI, VNI, and WNI.

[0021] 3, the switching elements UPC, VPC, UNC, and VNC included in the converter 110 and the switching elements UPI, VPI, WPI, UNI, VNI, and WNI included in the three-phase inverter 130 are IGBTs (insulated gate bipolar transistors), but are not limited to this. These switching elements UPC, VPC, UNC, VNC, UPI, VPI, WPI, UNI, VNI, and WNI may also be MOSFETs (metal oxide semiconductor field effect transistors), for example.

[0022] 3 shows an example in which the power conversion device 1 according to the first embodiment is applied to an AC-input electric vehicle, but the power conversion device 1 according to the first embodiment can also be applied to DC-input electric vehicles that are commonly used in subways, suburban electric vehicles, etc. When applied to a DC-input electric vehicle, the same configuration as that shown in FIG. 3 can be adopted, except that the transformer 106 and the converter 110 are not required.

[0023] Although FIG. 3 illustrates the converter 110 and the three-phase inverter 130 both as having a two-level circuit configuration, the present invention is not limited to this circuit configuration. Either one or both of the converter 110 and the three-phase inverter 130 may have a three-level circuit configuration. That is, the converter 110 may be a two-level converter and the three-phase inverter 130 may be a three-level three-phase inverter, or the converter 110 may be a three-level converter and the three-phase inverter 130 may be a two-level three-phase inverter, or the converter 110 may be a three-level converter and the three-phase inverter 130 may be a three-level three-phase inverter. Although FIG. 3 illustrates the case where the AC power supplied from the overhead line 101 is single-phase, the AC power supplied from the overhead line 101 may also be three-phase. When the AC power supplied from the overhead line 101 is three-phase, the converter 110 has a three-phase circuit configuration.

[0024] Fig. 4 is a diagram schematically illustrating the internal structure of a typical power semiconductor module. When a power semiconductor module 40 is for high power applications that generate a large amount of heat, it is generally mounted on a metal base plate 41, as shown in Fig. 4. An insulating substrate 42 is provided on the upper surface of the metal base plate 41, and multiple semiconductor chips 44 are disposed on the upper surface of the insulating substrate 42. A metal plate 43 is also provided on the metal base plate 41, and external electrodes 47 are provided on the metal plate 43. Multiple wire bonds 45 are used to electrically connect the semiconductor chips 44 and the external electrodes 47. For the wire bonds 45, metal wires such as gold, aluminum, or copper are used.

[0025] When the power conversion device 1 operates and current is repeatedly applied to the semiconductor chip 44, thermal stress gradually deteriorates the bond between the semiconductor chip 44 and the wire bonds 45. As the deterioration progresses, the bond between the semiconductor chip 44 and the wire bonds 45 comes loose. This phenomenon is called "lift-off." If this lift-off occurs in multiple wire bonds 45, the resistance value of the entire bond increases, and the power conversion device 1 cannot operate normally. Therefore, the power conversion device 1 according to the first embodiment performs a process to detect the deterioration state of the bond.

[0026] Fig. 5 is a diagram illustrating a component state detection unit provided in the control device according to embodiment 1. Fig. 5 shows an equivalent circuit including the semiconductor chip 44, wire bonds 45, and external electrodes 47 described in Fig. 4. Fig. 5 also shows the component state detection unit 24 and storage unit 21 provided in the control device 2. The component state detection unit 24 detects electrical characteristics related to the bonding state of the semiconductor chip 44 as the component state.

[0027] The semiconductor chip 44 includes an emitter auxiliary terminal 11, a gate terminal 12, an emitter electrode detection terminal 13, a collector electrode terminal 14, and an emitter electrode terminal 15. The emitter of the semiconductor chip 44 is connected to the emitter electrode terminal 15 via a plurality of wire bonds 45 and an external electrode 47. The collector of the semiconductor chip 44 is connected to the collector electrode terminal 14 via a plurality of wire bonds 46. Resistance Rt1 represents the resistance of the junction between the emitter of the semiconductor chip 44 and the wire bond 45, and the junction between the wire bond 45 and the external electrode 47. Resistance Rt2 represents the resistance of the junction between the collector of the semiconductor chip 44 and the wire bond 46, and the junction between the wire bond 46 and the collector electrode terminal 14.

[0028] The component state detection unit 24 is electrically connected to the first voltage terminal 11 and the second voltage terminal 13, and detects the voltage across the resistor Rt1. The component state detection unit 24 outputs the detected voltage value to the storage unit 21 as information about the component state. Here, the "component state" refers to the bonding state of multiple wire bonds in the semiconductor chip. The voltage value detected by the component state detection unit 24 is stored in the storage unit 21.

[0029] The voltage value detected by the component state detection unit 24 is an example of a physical quantity that represents the electrical characteristics of the semiconductor chip 44. Another example of a physical quantity is the resistance value of the joint in the semiconductor chip 44. If the current flowing through the semiconductor chip 44 is known, the resistance value of the joint can be calculated by a simple calculation from the detected voltage value. Therefore, the resistance value can be calculated by passing a specified value of current through the semiconductor chip 44, detecting the voltage value at that time, and dividing the detected voltage value by the specified value. This calculation process may be performed by the component state detection unit 24 or by the control device 2 that includes the memory unit 21.

[0030] 6 shows test results when three power semiconductor modules of the same type were subjected to thermal stress. The waveforms shown in Fig. 6 represent the voltage values ​​measured as a function of time when a specified current value is repeatedly passed intermittently through three power semiconductor modules 40 of the same type. The characteristic curves of the three power semiconductor modules 40 are shown by three different types of lines (dashed line, dashed line, and solid line).

[0031] 6, the vertical axis represents the normalized state value, and the horizontal axis represents the normalized time. The normalized state value is the detected voltage value normalized with the initial voltage value set to 1. The normalized time is the measurement time normalized by the time when the normalized state value reaches the specified value of "4.0 or more."

[0032] 6, a normalized state value of 1.0 indicates a brand new power semiconductor module that has never had a specified current flow through it. That is, a normalized state value of 1.0 indicates that the bonding state of the multiple wire bonds 45 in the semiconductor chip 44 is sound. A normalized state value of 4.0 or higher indicates that lift-off has occurred in almost all of the wire bonds 45 due to thermal stress, and that the power semiconductor module 40 has almost completely deteriorated.

[0033] In this paper, the curves shown in Figure 6 are referred to as "deterioration curves." In the example shown in Figure 6, three power semiconductor modules of the same type were tested. The time at which the normalized state value reached 4.0 or higher, i.e., the time at which the power semiconductor module 40 reached a nearly completely degraded state, varied. However, when normalized time is used as the horizontal axis, the deterioration curves of these three power semiconductor modules 40 closely match. This means that even if there is individual variation in the rate at which degradation progresses for the power semiconductor module 40, the individual variation in the change in the normalized state value as degradation progresses is small. Therefore, the deterioration curves can be used to accurately detect the degradation state of the power semiconductor module 40 from the normalized state value. As shown in Figure 6, the normalized state values ​​are nearly identical until the normalized time reaches "0.7." Furthermore, after the normalized time = 0.7, there are some differences due to the characteristic that the normalized state value changes significantly even with a slight change in time, but the degradation trends are consistent. Therefore, it is believed that if a large number of deterioration curves are used and the average of these deterioration curves is obtained by statistically processing them, the deterioration state of the power semiconductor module 40 can be estimated with high accuracy.

[0034] 7 is a diagram illustrating that the deterioration curves described in FIG. 6 may change depending on differences in the surrounding environment. The following two points are considered as examples of such differences in the surrounding environment of the power semiconductor module 40: (1) The cooling performance of the coolers of the power semiconductor modules 40 is different; and (2) The positions on the coolers of the power semiconductor modules 40 are different.

[0035] Regarding (1), if the cooling performance of the cooler of the power semiconductor module 40 is poor, thermal interference occurs between the multiple power semiconductor chips inside the power semiconductor module 40. In other words, the temperature of the power semiconductor chip in the center is higher than the temperature of the power semiconductor chips on the periphery. Because of the large temperature difference, there is a large difference in the time when the connection between the semiconductor chip 44 and the wire bond 45 is completely broken and current cannot flow between the multiple power semiconductor chips inside the power semiconductor module 40. Therefore, the deterioration curve becomes a curve shown by the dashed line in Figure 7. In other words, changes in the normalized state value can be seen from a relatively early stage in the normalized time.

[0036] Regarding (1), if the cooling performance of the cooler of the power semiconductor module 40 is good, heat is efficiently transferred to the cooler, whether it is a power semiconductor chip in the center of the power semiconductor module 40 or a power semiconductor chip on the periphery of the power semiconductor module 40. In other words, the temperature difference between the multiple power semiconductor chips inside the power semiconductor module 40 is small. Because the temperature difference is small, the difference in time between the multiple power semiconductor chips inside the power semiconductor module 40 when the connection between the semiconductor chip 44 and the wire bond 45 is completely broken and current cannot flow is small. Therefore, the deterioration curve is as shown by the solid line in Figure 7. In other words, changes in the normalized state value are observed relatively late in the normalized time.

[0037] Regarding (2), when the power semiconductor modules 40 are electrically connected in parallel and are positioned differently on the cooler, there may be a large difference in cooling performance. This results in a large difference in the time when the connection between the semiconductor chip 44 and the wire bond 45 is completely broken and current cannot flow. Therefore, the deterioration curve becomes a curve such as the dashed line in Figure 7. In other words, changes in the normalized state value can be seen from a relatively early stage in the normalized time.

[0038] As described above, the deterioration curve may change depending on the difference in the surrounding environment of the power semiconductor module 40. To respond to the change in the deterioration curve, the correction unit 22 provided in the control device 2 corrects the current deterioration curve. FIG. 8 is a diagram illustrating the correction process of the deterioration curve in the first embodiment. FIG. 9 is a flowchart illustrating the operation of the control device including the correction process of the deterioration curve in the first embodiment. In the description of FIG. 9 , the power conversion device 1 that performs the correction process of the deterioration curve is referred to as the "own device," and the power conversion devices 1 other than the own power conversion device are referred to as the "other devices."

[0039] In FIG. 9 , a degradation curve is first stored in the memory unit during product manufacturing (step S11). For long-life components, the degradation curve is obtained by artificial degradation testing of the components. In FIG. 8 , this corresponds to the degradation curve indicated by the solid line. The component status detection unit 24 detects the component status of its own device during product operation (step S12). Specifically, the component status detection unit 24 detects physical quantities representing the electrical characteristics of components included in its own device as the component status. The control device 2 transmits component status data representing the detected component status to the in-train communication network 8 (step S13). The memory unit 21 of its own device stores both the component status data of its own device and the component status data of other devices, and the correction unit 22 of its own device corrects the degradation curve using both stored component status data (step S14). In FIG. 8 , this corresponds to the degradation curve indicated by the dashed dotted line. Statistical processing is used to correct the degradation curve. Furthermore, since the deterioration curve is corrected using not only the component status data of the own device but also the component status data of other devices, the amount of data is large, and the accuracy of the deterioration curve correction can be improved. The deterioration state detection unit 23 detects the deterioration state of the components of the own device using the corrected deterioration curve (step S15). Thereafter, as the operating time of the device increases and the component status data increases, the process returns to step S12 and repeats the correction of the deterioration curve.

[0040] The correction process in step S14 will be further described with reference to FIG. 8 . First, in step S11, a deterioration curve is stored in the memory unit 21 during product manufacturing. This deterioration curve is a deterioration curve using all data up to complete destruction. On the other hand, since the component status data is obtained during operation of the power conversion device, data up to the middle of the deterioration is obtained. To correct the entire deterioration curve using data up to the middle of the deterioration, the control device 2 is provided with the following judgment values ​​and performs processing. Specifically, the control device 2 is set with a first level A1 and a second level A2, which is greater than the first level A1, as judgment values ​​for determining the current level of the normalized state value. In the first deterioration curve indicated by the solid line, the correction unit 2 calculates the normalized time T1 at which the normalized state value reaches the first level A1 and the difference ΔT1 between the normalized time T1′ at which the normalized state value reaches the second level A2 and the normalized time T1. Furthermore, the correction unit 22 calculates a first deterioration ratio ΔT1 / T1, which is the ratio of the difference ΔT1 to the normalized time T1. Similarly, the correction unit 22 calculates a second deterioration ratio ΔT2 / T2 based on the normalized time T2 at which the normalized state value reaches the first level A1 and the difference ΔT2 between the normalized time T2' at which the normalized state value reaches the second level A2 and the normalized time T2, in the second deterioration curve shown by the dotted line.

[0041] 8 shows an example in which the first degradation ratio ΔT1 / T1 is smaller than the second degradation ratio ΔT2 / T2. The second degradation ratio ΔT2 / T2 is a value calculated based on component status data including not only the component status data of the device itself but also the component status data of other devices, and is a value that conforms to the actual usage environment, i.e., the actual situation. Therefore, the correction unit 22 uses the second degradation ratio ΔT2 / T2 to correct the first degradation curve, which is the device's own degradation curve.

[0042] Although the above description has been given assuming that the degradation curve indicated by the solid line corresponds to the first degradation curve and the degradation curve indicated by the dashed-dotted line corresponds to the second degradation curve, the reverse pattern is also possible. When the conditions of the usage environment are less severe than expected, it is also possible that the degradation curve indicated by the dashed-dotted line corresponds to the first degradation curve and the degradation curve indicated by the solid line corresponds to the second degradation curve. However, in either case, the first degradation curve is corrected based on values ​​calculated based on multiple component status data, including not only the first component status data but also the second component status data. Therefore, in either case, the degradation curve is corrected to match the actual situation, thereby improving the accuracy of component status degradation determination.

[0043] As described above, the power conversion device according to the first embodiment is a power conversion device used for propulsion control of a train consisting of a plurality of railway cars, and includes a component state detection unit, a storage unit, a correction unit, and a deterioration state detection unit. The component state detection unit detects physical quantities representing electrical characteristics of components included in the power conversion device as component states. The storage unit stores first component state data representing component states of its own power conversion device and second component state data representing component states of other power conversion devices transmitted from the other power conversion devices via an in-train communication network. The storage unit also stores a first deterioration curve created using the first component state data and a second deterioration curve created using the first and second component state data. The correction unit corrects the first deterioration curve using the second deterioration curve. The deterioration state detection unit detects the deterioration states of the components using the corrected first deterioration curve. In the power conversion device configured as described above, the second deterioration curve is created based on the second component status data transmitted from multiple power conversion devices other than the power conversion device itself, and therefore is a correction curve that is tailored to the actual situation. Therefore, the first deterioration curve corrected using the second deterioration curve is also corrected to a correction curve that is tailored to the actual situation. Therefore, by using the power conversion device according to the first embodiment, the deterioration state of the components can be accurately determined even if the deterioration is determined during the wear-out failure period, thereby enabling accurate detection of an abnormality in the power conversion device. Furthermore, in the power conversion device according to the first embodiment, the first deterioration curve is corrected to a correction curve that is tailored to the actual situation, and therefore, accurate detection of an abnormality in the power conversion device can be enabled even if the deterioration is determined during the random failure period.

[0044] When the power conversion device according to the first embodiment includes a three-phase inverter that converts DC power into AC power for the propulsion motor, the first and second component status data may be data representing the component status of components included in the three-phase inverter. In this case, the second component status data may be component status data transmitted from a plurality of other power conversion devices present in the same railcar that constitutes a train, or may be component status data transmitted from a plurality of other power conversion devices present in the same railcar and in different railcars that constitute the train.

[0045] When the power conversion device according to the first embodiment is a power conversion device mounted on an AC-input electric vehicle and includes a converter that converts AC power into DC power, the first and second component status data may be data representing the component status of components included in the converter. In this case, the second component status data may be component status data transmitted from a plurality of other power conversion devices present in the same railcar that constitutes a train, or may be component status data transmitted from a plurality of other power conversion devices present in the same railcar and in different railcars that constitute the train.

[0046] An example of a component detected by the component state detection unit is a power semiconductor module included in a three-phase inverter or converter. In this example, the component state detection unit detects the electrical resistance of the power semiconductor module as the bonding state of multiple wire bonds in a semiconductor chip. Another example of a component detected by the component state detection unit is a filter capacitor included in a power conversion main circuit. In this example, the component state detection unit may detect the charge time and discharge time of the filter capacitor as component state data. By detecting the charge time and discharge time of the filter capacitor as component state data, it becomes possible to objectively determine the degree of capacitance degradation of the filter capacitor in one power conversion device by comparing it with filter capacitors in other power conversion devices.

[0047] Second Embodiment In the first embodiment, it has been mentioned that the deterioration curve of the power semiconductor module 40 changes depending on the difference in the surrounding environment, and it has also been mentioned that the change in the deterioration curve due to the difference in the surrounding environment is related to the cooling performance of the cooler and the position on the cooler where the power semiconductor module 40 is attached. In the second embodiment, a control method that takes these differences in the surrounding environment into consideration will be described.

[0048] FIG. 10 is a diagram illustrating the flow of heat when a power semiconductor module mounted on a cooler is operating. When a power semiconductor module 40 is a high-power module that generates a large amount of heat, it is often mounted on a cooler 48, as shown in FIG. 10 . The power semiconductor module 40 incorporates multiple semiconductor chips 44, and the temperature rise of the semiconductor chips 44 due to heat generation depends on the cooling performance of the cooler 48. If the cooling performance of the cooler 48 is good, the heat generated by the semiconductor chips 44 moves in the direction of the cooler 48, that is, downward in the case of the configuration shown in FIG. 10 . In this case, thermal interference between the semiconductor chips 44 is small, and the temperature difference between the semiconductor chips 44 is small. As a result, the variation in thermal stress experienced by the semiconductor chips 44 is small.

[0049] In contrast, if the cooling performance of the cooler 48 is poor, the heat generated by the semiconductor chips will move not only downward in FIG. 10 but also horizontally in FIG. 10. In this case, thermal interference between the semiconductor chips 44 will increase, and the temperature difference between the semiconductor chips 44 will also increase. As a result, the thermal stress that the semiconductor chips 44 receive will vary greatly between the semiconductor chips 44.

[0050] As described above, the actual cooling performance of the cooler 48 differs from the cooling performance assumed at the time of design of the cooler 48. Therefore, a difference occurs between the deterioration curve assumed at the time of design and the actual deterioration curve.

[0051] 11 is a diagram showing an example of a case where a power semiconductor module provided in a three-phase inverter included in the power conversion device according to embodiment 1 is mounted on a cooler. When the power conversion device 1 according to embodiment 1 is a power conversion device for a railway vehicle, a power semiconductor module 49 is mounted on a cooler 48 that uses cooling air generated by the running wind. The cooler 48 is a self-cooling type that uses the running wind, and cooling air passes through the cooler 48 as the railway vehicle moves.

[0052] The three-phase inverter 130 includes nine power semiconductor modules 49. Each power semiconductor module 49 is a two-element module in which two switching elements constituting each phase leg are housed within one module. In FIG. 11 , the nine power semiconductor modules 49u1 to 49u3, 49v1 to 49v3, and 49w1 to 49w3 are arranged in a square lattice of three rows and three columns on a first surface 48a, which is the module mounting surface of the cooler 48. In other words, the nine power semiconductor modules 49u1 to 49u3, 49v1 to 49v3, and 49w1 to 49w3 are arranged in columns of three on the first surface 48a along a second direction perpendicular to the first direction in which cooling air flows. When the rows are arranged from left to right along the first direction as the first, second, and third rows, power semiconductor modules 49u1 to 49u3 are arranged in the first row, power semiconductor modules 49v1 to 49v3 are arranged in the second row, and power semiconductor modules 49w1 to 49w3 are arranged in the third row.

[0053] The power semiconductor modules 49u1 to 49u3 form a U-phase leg, the power semiconductor modules 49v1 to 49v3 form a V-phase leg, and the power semiconductor modules 49w1 to 49w3 form a W-phase leg. That is, each phase leg is made up of three two-element modules connected in parallel.

[0054] Since a railway vehicle travels on the outbound and inbound routes without changing its direction, the direction of the cooling air is opposite on the outbound and inbound routes. Therefore, the power semiconductor modules 49 arranged in the first and third rows are sometimes on the upstream side of the cooling air and sometimes on the downstream side. As a result, the temperature difference between the upstream and downstream sides of the power semiconductor modules 49 arranged in the first and third rows is large. In contrast, the power semiconductor modules 49 arranged in the second row are always located in the second row on both the upstream and downstream sides, so the temperature difference due to the difference in traveling direction is small.

[0055] Furthermore, the power semiconductor modules 49 arranged around the periphery of the square lattice have a lower average temperature because they are subject to less thermal interference from the other power semiconductor modules 49. In contrast, the power semiconductor module 49 attached to the center of the square lattice has a higher average temperature because it is subject to greater thermal interference from the other power semiconductor modules 49.

[0056] As described above, when the power conversion device 1 is a self-cooling type power conversion device that utilizes wind from running, the temperature difference between the power semiconductor modules 49 and the average temperature are different, so in the second embodiment, they are managed as follows.

[0057] The first power semiconductor module disposed at the center of the nine power semiconductor modules and the eight second power semiconductor modules disposed around the first power semiconductor module are distinguished as power semiconductor modules placed in different environments and are managed as different component state data. By managing them in this manner, statistical processing is performed between component state data showing similar deterioration trends, thereby improving the accuracy of correction of the deterioration curve.

[0058] Alternatively, the six power semiconductor modules arranged in the first and third rows and the three power semiconductor modules arranged in the second row are distinguished as power semiconductor modules placed in different environments and managed as different component state data. Even when managed in this manner, statistical processing is performed between component state data showing similar deterioration trends, thereby improving the accuracy of correction of the deterioration curve.

[0059] 11 illustrates an example in which the number of power semiconductor modules 49 included in the three-phase inverter 130 is nine, but the number may be other than nine. Even in other examples, the accuracy of correction of the deterioration curve can be improved by distinguishing and managing the component status data having similar deterioration trends so that statistical processing is performed between them.

[0060] As described above, according to the power conversion device of embodiment 2, component status data with similar deterioration trends are managed separately so that statistical processing is performed between them, thereby making it possible to improve the accuracy of correction of the deterioration curve.

[0061] Third Embodiment Fig. 12 is a diagram showing an example of the configuration of a deterioration detection system according to a third embodiment. A deterioration detection system 80 according to the third embodiment is composed of power conversion devices 3a to 3d each equipped with control devices 4a to 4d, and a processing device 50. In Fig. 12, components that are the same as or equivalent to those in Fig. 1 are given the same reference numerals. Duplicate descriptions of the same or equivalent components will be omitted.

[0062] The processing device 50 is connected to the communication network 8 so that data can be shared between the power conversion devices 3a to 3d. The processing device 50 is also configured to be able to communicate with the ground device 60, which will be described later. The processing device 50 has the functions of the storage unit 21, the correction unit 22, and the deterioration state detection unit 23 in the control device 2 described in the first embodiment. Therefore, the control device 4 according to the third embodiment does not need to have the functions of the correction unit 22 and the deterioration state detection unit 23. Furthermore, in the control device 4 according to the third embodiment, the storage unit 21 stores the component state data detected by the component state detection unit 24 and transmits it to the processing device at any timing.

[0063] Fig. 13 is a diagram showing an example of the configuration of a processing device according to embodiment 3. The processing device 50 manages component status data, which is data representing the status of components of the power conversion device 3 and is transmitted from the power conversion device 3 via the communication network 8 within the train. To achieve this function, the processing device 50 includes a storage unit 51, a correction unit 52, and a deterioration state detection unit 53, as shown in Fig. 13 .

[0064] The storage unit 51 stores first component status data representing component statuses of components in the first power conversion device and second component status data representing component statuses of components in the second power conversion device. The first power conversion device refers to any one of the power conversion devices 3a to 3d, and the second power conversion device refers to a power conversion device other than the first power conversion device. The storage unit 51 also stores a first deterioration curve created using the first component status data and a second deterioration curve created using the first and second component status data. The correction unit 52 corrects the second deterioration curve using the first deterioration curve. The deterioration state detection unit 53 detects the deterioration state of the components using the first deterioration curve and the corrected second deterioration curve.

[0065] The storage unit 51 can be realized by a non-volatile or volatile semiconductor memory such as a RAM, flash memory, EPROM, or EEPROM (registered trademark), or a magnetic disk, optical disk, or DVD. The correction unit 52 and the deterioration state detection unit 53 can be realized by a processor such as a CPU (Central Processing Unit). The processor executes a program in which processing is described. The storage unit 51 also stores programs to be executed by the correction unit 52 and the deterioration state detection unit 53, as well as necessary data obtained during the processing. The storage unit 51 is also used as a temporary storage area for the programs. Note that the configuration in FIG. 13 is an example, and the configuration of the device is not limited to the example in FIG. 13.

[0066] The functions of the processing device 50 described above may be implemented in a train information management device that manages train information transmitted inside the vehicle. Existing train information management devices have a communication function with the power conversion device 3 and a communication function with the ground. Therefore, by using an existing train information management device, the cost of building the system can be reduced.

[0067] 14 is a diagram showing an example of the configuration of a ground device that cooperates with the deterioration detection system according to Embodiment 3. The ground device 60 includes a receiving unit 61, a storage unit 62, and an output unit 63.

[0068] The receiving unit 61 receives the detection results from the processing device 50 of the deterioration detection system 80. The receiving unit 61 may also receive information regarding a deterioration curve, if necessary. The memory unit 62 stores the received detection results. When storing the detection results, the memory unit 62 stores them in association with identification numbers for identifying the vehicle and the part. The output unit 63 is composed of a display, a liquid crystal display panel, a printer, etc., and displays various screens to the user of the computer system and provides necessary information on paper media. Note that the configuration in FIG. 14 is an example, and the configuration of the device is not limited to the example in FIG. 14.

[0069] As described above, the deterioration detection system according to the third embodiment includes a power converter used for train propulsion control and a processing device that manages component status data representing the status of components of the power converter and transmitted from the power converter via a communication network within the train. Each power converter in the train includes a component status detector that detects the status of components included in the power converter. The processing device includes a memory unit, a correction unit, and a deterioration state detection unit. The memory unit stores first component status data representing the component status of components in a first power converter and second component status data representing the component status of components in a second power converter, which is a power converter other than the first power converter. The memory unit also stores a first deterioration curve created using the first component status data and a second deterioration curve created using the first and second component status data. The correction unit corrects the first deterioration curve using the second deterioration curve. The degradation state detection unit detects the degradation state of the components in the first power electronics device using the corrected first degradation curve. The processing device can perform the component degradation state detection process for all power electronics devices by replacing the first power electronics device with another power electronics device and repeating the above process. In the degradation detection system according to the third embodiment, the processing device can be configured as a computer system, and the first and second component state data can be managed in a unified manner in the processing device, thereby enabling faster processing than in the first embodiment.

[0070] In the third embodiment, the first and second component status data are component status data transmitted from a plurality of power electronics devices in the railcars of a train. However, the first and second component status data may be component status data transmitted from a plurality of other power electronics devices in the railcars of other trains traveling on the same line as the train. In this way, the number of first and second component status data increases, thereby improving the accuracy of correcting the deterioration curve. As a result, the accuracy of determining deterioration of the component status also improves.

[0071] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or different embodiments may be combined with each other. It is also possible to omit or modify parts of the configurations as long as they do not deviate from the gist of the invention.

[0072] REFERENCE SIGNS LIST 1, 1a to 1d, 3, 3a to 3d power conversion devices, 2, 2a to 2d, 4, 4a to 4d control devices, 8 communication network, 11 emitter auxiliary terminal, 12 gate terminal, 13 emitter electrode detection terminal, 14 collector electrode terminal, 15 emitter electrode terminal, 21, 51, 62 memory unit, 22, 52 correction unit, 23, 53 deterioration state detection unit, 24 component state detection unit, 40, 49, 49u1 to 49u3, 49v1 to 49v3, 49w1 to 49w3 power semiconductor module, 41 metal base plate, 42 insulating substrate, 43 metal plate, 44 semiconductor chip, 45, 46 wire bond, 47 external electrode, 48 cooler, 48a first surface, 50 processing device, 60 ground device, 61 receiving unit, 63 output unit, 80 Deterioration detection system, 100 railway vehicle, 101 overhead wire, 102 current collector, 103 wheel, 104 rail, 106 transformer, 110 converter, 120 filter capacitor, 130 three-phase inverter, 140 traction motor, 150 power conversion main circuit, UPC, VPC, UNC, VNC, UPI, VPI, WPI, UNI, VNI, WNI switching elements.

Claims

1. A power conversion device used in a train made up of a plurality of railway cars, comprising: a component status detection unit that detects physical quantities representing electrical characteristics of components provided in the power conversion device as component status; a memory unit that stores first component status data that is data representing the component status of its own power conversion device and second component status data that is data representing the component status of another power conversion device and is transmitted from the other power conversion device through a communication network within the train, and also stores a first deterioration curve created using the first component status data and a second deterioration curve created using the first and second component status data; a correction unit that corrects the first deterioration curve using the second deterioration curve; and a deterioration status detection unit that detects the deterioration status of the components using the corrected first deterioration curve.

2. The power conversion device according to claim 1, characterized in that: the power conversion device includes a three-phase inverter that converts DC power into AC power for a propulsion motor; the first and second component status data are data representing the component status of components included in the three-phase inverter; and the second component status data is transmitted from a plurality of other power conversion devices present in the same railcar that constitutes the train.

3. The power conversion device according to claim 1, characterized in that: the power conversion device includes a three-phase inverter that converts DC power into AC power for a propulsion motor; the first and second component status data are data representing the component status of components included in the three-phase inverter; and the second component status data is transmitted from a plurality of other power conversion devices present in the same car and in different cars of a railway vehicle that constitutes the train.

4. The power conversion device according to claim 1, characterized in that the power conversion device comprises a converter that converts AC power into DC power and a three-phase inverter that converts the DC power into AC power for a propulsion motor, the first and second component status data are data representing the component status of components provided in the converter, and the second component status data is transmitted from a plurality of other power conversion devices present in the same railcar that constitutes the train.

5. The power conversion device according to claim 1, characterized in that the power conversion device comprises a converter that converts AC power into DC power and a three-phase inverter that converts the DC power into AC power for a propulsion motor, the first and second component status data are data representing the component status of components provided in the converter, and the second component status data is transmitted from a plurality of other power conversion devices present in the same car and in different cars of a railway vehicle that constitutes the train.

6. The power conversion device according to any one of claims 2 to 5, characterized in that the power conversion device comprises a power semiconductor module in which a semiconductor chip and external electrodes are joined by a plurality of wire bonds, and the component state detection unit detects the electrical resistance of the power semiconductor module as the joining state of the plurality of wire bonds in the semiconductor chip.

7. The power conversion device according to claim 6, characterized in that: the three-phase inverter comprises nine power semiconductor modules in which semiconductor chips and external electrodes are joined by a plurality of wire bonds; the power conversion device comprises a cooler for cooling the nine power semiconductor modules; the nine power semiconductor modules are arranged in a square lattice of 3 rows and 3 columns on a first surface which is a module mounting surface of the cooler; and one first power semiconductor module arranged at the center of the nine power semiconductor modules and eight second power semiconductor modules arranged around the first power semiconductor module are distinguished as power semiconductor modules placed in different environments and are managed as different component state data.

8. The power conversion device according to claim 6, characterized in that: the three-phase inverter comprises nine power semiconductor modules in which semiconductor chips and external electrodes are joined by a plurality of wire bonds; the power conversion device comprises a cooler that cools the nine power semiconductor modules; the nine power semiconductor modules are arranged in rows of three on a first surface that is a module mounting surface of the cooler along a second direction that is perpendicular to a first direction in which cooling air flows; and when the nine power semiconductor modules are arranged in a first row, a second row, and a third row in order along the first direction, the six power semiconductor modules arranged in the first row and the third row and the three power semiconductor modules arranged in the second row are distinguished as power semiconductor modules placed in different environments and are managed as different component state data.

9. A power conversion device as described in any one of claims 6 to 8, characterized in that the first and second deterioration curves are curves that represent the relationship between a normalized state value obtained by normalizing the value of the physical quantity of the component at the time of detection to 1 as the value of the physical quantity of the component in its initial state, and a normalized time obtained by normalizing the usage time of the component by the time until the physical quantity of the component reaches a specified value.

10. The power conversion device according to claim 9, characterized in that each of the power conversion devices is provided with a display unit configured to be able to display the detection result by the deterioration state detection unit.

11. A deterioration detection system comprising: a power conversion device used in a train consisting of a plurality of railcars; and a processing device for managing component status data representing the status of components of the power conversion device and transmitted from the power conversion device through a communication network within the train, and detecting a deterioration state of the components based on the component status data, wherein each of the power conversion devices present in the train is equipped with a component status detector for detecting the status of components provided in the power conversion device, the processing device comprising: a memory unit that stores first component status data which is data representing the component status of the components in a first power conversion device and second component status data which is data representing the component status of components of a second power conversion device which is a power conversion device other than the first power conversion device, and stores a first deterioration curve created using the first component status data and a second deterioration curve created using the first and second component status data; a correction unit that corrects the first deterioration curve using the second deterioration curve; and a deterioration state detection unit that detects the deterioration state of the components in the first power conversion device using the corrected first deterioration curve. A deterioration detection system comprising:

12. The deterioration detection system described in claim 11, characterized in that the first and second component condition data are also transmitted from a plurality of other power conversion devices present in railway vehicles of other trains traveling on the same line as the train.

13. A ground device that cooperates with the deterioration detection system described in claim 11 or 12, characterized in that it comprises: a receiving unit that receives information regarding the component status of the power conversion device from the deterioration detection system; a memory unit that stores the received information regarding the component status; and an output unit that outputs or displays the information stored in the memory unit.

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