Power conversion equipment for rail vehicles

Abstract

A power conversion device (50) comprises: a three-phase inverter (4) that converts direct-current power to alternating-current power for a propulsion motor (15); and a magnetic core (8). The magnetic core (8) comprises: first and second cores (8a, 8b) that are passed through both a three-phase alternating-current power line (5) and a common-mode current return line (6); and a third core (8c) that is passed through only the three-phase alternating-current power line (5). The first core (8a) is arranged on the three-phase inverter (4) side, the second core (8b) is arranged on the propulsion motor (15) side, and the third core (8c) is arranged between the first core (8a) and the second core (8b). When led out to the propulsion motor (15) side from the second core (8b) of the first, second, and third cores (8a–8c), at least one electrical wiring of the three electrical wirings that constitute the three-phase alternating-current power line (5) is led out so as not to be parallel to one or two of the other electrical wirings.

Description

[Technical field]

[0001] The present disclosure relates to a power conversion device for a railway vehicle for driving a traction motor mounted on the railway vehicle. [Background technology]

[0002] Power conversion devices include switching elements such as IGBTs (Insulated Gate Bipolar Transistors), MOSFETs (Metal-Oxide-Semiconductor Field-Effect-Transistors), etc. In recent power conversion devices, switching voltages have increased and switching operations have become faster due to the higher voltage resistance and higher frequency of switching elements.

[0003] It is generally known that the switching operation in a power conversion device causes a common mode current, which is a zero-phase current. It is also known that the switching operation in a power conversion device causes a leakage current flowing to the ground through a parasitic capacitance between the AC power line connecting the power conversion device and a load and the ground. It is also known that the switching operation in a power conversion device causes a leakage current flowing to peripheral devices other than the load through a parasitic capacitance between the AC power line and a housing that houses the power conversion device. These leakage currents are distinguished from zero-phase currents as common mode currents that flow in a ground system.

[0004] As described above, an increase in switching voltage and a high-speed switching operation increase zero-phase current and leakage current, and increase radiated noise and conducted noise, which can adversely affect surrounding communication devices and the like.

[0005] In order to reduce the zero-phase current, it has been customary to wind AC power lines around or through the same magnetic core. In addition, the following Patent Document 1 discloses a technique for reducing leakage current by connecting the ground terminal of a power conversion device and the ground terminal of a load with an electric wiring called a common mode current return line, and winding the AC power line and the common mode current return line around or through the same magnetic core. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2001-086734 A Summary of the Invention [Problem to be solved by the invention]

[0007] When the technology of Patent Document 1 is used, the impedance of the return loop of the ground circuit becomes larger than the impedance of the return loop of the common mode current return line, so that the leakage current flowing through the return loop of the ground circuit can be reduced. However, it is explained that when the technology of Patent Document 1 is used, the peak value of the zero-phase current becomes larger than when only the AC power line is wound around or passed through the same magnetic core. As described above, the zero-phase current causes radiated noise and conducted noise. In the case of a power conversion device for a railway vehicle, an extremely large current flows through the traction motor, which is the load, so an increase in the zero-phase current cannot be tolerated.

[0008] The present disclosure has been made in consideration of the above, and has an object to provide a power conversion device for railway vehicles that can reduce leakage current while preventing an increase in zero-phase current. [Means for solving the problem]

[0009] In order to solve the above problems and achieve the object, a power conversion device for a railway vehicle according to the present disclosure is a power conversion device for a railway vehicle for driving a propulsion motor mounted on the railway vehicle, and includes a three-phase inverter that converts DC power into AC power for the propulsion motor, and a magnetic core through which a three-phase AC power line and a common mode current return line pass. The three-phase AC power line is an electric wiring that connects the three-phase inverter and the propulsion motor, and the common mode current return line is an electric wiring that connects between the ground potential of the power conversion device and the ground potential of the propulsion motor. The magnetic core has first and second cores through which both the three-phase AC power line and the common mode current return line pass, and a third core through which only the three-phase AC power line passes. The first core is arranged on the side of the three-phase inverter, and the second core is arranged on the side of the propulsion motor. In addition, the third core is arranged between the first core and the second core. In each of the first, second and third cores, the surface facing the three-phase inverter is defined as the first surface, and the surface facing the traction motor is defined as the second surface. When at least one of the three electrical wirings constituting the three-phase AC power line is pulled out from the second core to the second surface side, it is not parallel to the other one or two electrical wirings. Effect of the Invention

[0010] The power conversion device for a railway vehicle according to the present disclosure has the effect of reducing leakage current while preventing an increase in zero-phase current. [Brief description of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram showing an example of the configuration of an electrical system of a railway vehicle system including a power conversion device according to a first embodiment. [Diagram 2] FIG. 2 shows an example of a variation of the input circuit shown in FIG. 1. [Diagram 3] FIG. 1 is a diagram for explaining the configuration of a magnetic core provided in a power conversion device according to a first embodiment and the positional relationship with a three-phase AC power line and a common mode current return line. [Figure 4]FIG. 10 is a diagram for explaining the effect when the magnetic core provided in the power conversion device according to the first embodiment is used. [Diagram 5] FIG. 1 is a diagram showing a configuration example of a magnetic core according to a first embodiment used in an electromagnetic field analysis; [Figure 6] FIG. 6 is a diagram showing a configuration example of a magnetic core shown as a comparative example of FIG. 5; [Figure 7] FIG. 7 is a diagram for explaining an electromagnetic field analysis performed on the magnetic core having the configurations of FIGS. 5 and 6. [Figure 8] A diagram to explain why the analysis results shown in Fig. 7 are obtained. [Figure 9] FIG. 5 is a diagram showing a situation where local magnetic flux is generated as described in the first embodiment on the configuration diagram of the magnetic core in FIG. [Figure 10] FIG. 11 is a diagram for explaining the configuration of a magnetic core provided in a power conversion device according to a second embodiment. [Figure 11] FIG. 13 is a diagram for explaining the configuration of a magnetic core provided in a power conversion device according to a fourth embodiment. [Figure 12] FIG. 13 is a diagram for explaining the configuration of a magnetic core provided in a power conversion device according to a fifth embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] A power conversion device for railway vehicles according to an embodiment of the present disclosure (hereinafter, appropriately abbreviated as "power conversion device") will be described in detail below with reference to the attached drawings. Note that in the attached drawings, the scale of each component may differ from the actual scale in order to facilitate understanding. The same applies to each of the drawings. In addition, in the following description, no distinction is made between physical connection and electrical connection, and the term "connection" is used. In other words, the term "connection" includes both cases where components are directly connected to each other and cases where components are indirectly connected to each other via other components.

[0013] Embodiment 1 Fig. 1 is a diagram showing an example of the configuration of an electrical system of a railway vehicle system including a power conversion device 50 according to the first embodiment. The power conversion device 50 according to the first embodiment includes a filter capacitor 3, a three-phase inverter 4, and a magnetic core 8. In Fig. 1, an input circuit unit 2 is connected to an input end of the three-phase inverter 4, and at least one traction motor 15 is connected to an output end of the three-phase inverter 4. The traction motor 15 is a three-phase motor that provides a propulsive force to the railway vehicle.

[0014] The input circuit unit 2 is configured to include at least a switch and a filter reactor. One end of the input circuit unit 2 is connected to an overhead line 10 via a current collector 11, and the other end is connected to a rail 12 at earth potential via a wheel 13. DC power or AC power supplied from the overhead line 10 is input to one end of the input circuit unit 2 via the current collector 11. A DC voltage due to the DC power generated at the output end of the input circuit unit 2 is applied to a three-phase inverter 4. The filter capacitor 3 smoothes the DC voltage so that the ripple of the DC voltage applied to the three-phase inverter 4 is reduced. The three-phase inverter 4 converts the DC power supplied via the input circuit unit 2 into AC power for the propulsion motor 15.

[0015] The three-phase inverter 4 is connected to the propulsion motor 15 by a three-phase AC power line 5 via a magnetic core 8. The three-phase AC power line 5 is electrical wiring that connects the three-phase inverter 4 and the propulsion motor 15. A housing (not shown) of the propulsion motor 15 is grounded by a ground wire 7. The propulsion motor 15 is also connected to a portion of the power conversion device 50 that is at the ground potential by a common mode current return line 6. The common mode current return line 6 is electrical wiring that electrically connects the ground potential of the power conversion device 50 and the ground potential of the propulsion motor 15.

[0016] The three-phase inverter 4 includes a plurality of switching elements 4a connected in a three-phase bridge configuration. The switching elements 4a have free wheel diodes connected in anti-parallel. The switching elements 4a perform switching operations in accordance with a gate signal output from a control unit (not shown). The switching operations of the switching elements 4a control the current flowing through the switching elements 4a intermittently. This converts the DC power supplied from the input circuit unit 2 into AC power for the traction motor 15. The traction motor 15 is driven by the AC power supplied from the three-phase inverter 4, and provides propulsive force to a train made up of one or more railcars (not shown). The three-phase inverter 4 drives the traction motor 15 by converting the DC power supplied via the input circuit unit 2 into AC power for the traction motor 15. Note that, although the input circuit unit 2 and the three-phase inverter 4 are illustrated as separate components in FIG. 1, they may be configured to be housed in the same housing.

[0017] Fig. 2 is a diagram showing an example of a variation of the input circuit unit 2 shown in Fig. 1. Fig. 2 shows an input circuit unit 2A as an example in which the overhead line 10 is an AC overhead line. The input circuit unit 2A includes a main transformer 21 and a converter 22. The main transformer 21 steps down the AC voltage received via the current collector 11 and applies it to the converter 22. The converter 22 converts the stepped-down AC voltage into a DC voltage and applies it to the three-phase inverter 4.

[0018] Next, the configuration and connection form of the magnetic core 8 will be described with reference to Fig. 1 and Fig. 3. Fig. 3 is a diagram for explaining the configuration of the magnetic core 8 provided in the power conversion device 50 according to the first embodiment and the positional relationship with the three-phase AC power line 5 and the common mode current return line 6.

[0019] The magnetic core 8 is composed of a first core 8a arranged on the side of the three-phase inverter 4, a second core 8b arranged on the side of the traction motor 15, and a third core 8c arranged between the first core 8a and the second core 8b. The first core 8a, the second core 8b, and the third core 8c are formed in a circular ring shape as shown in Fig. 3. It goes without saying that the "circular" mentioned here does not only mean a perfect circle shape, but also includes an elliptical shape.

[0020] Each of the cores, consisting of the first core 8a, the second core 8b, and the third core 8c, is arranged such that when the surface facing the three-phase inverter 4 is defined as a first surface and the surface facing the traction motor 15 is defined as a second surface, the first and second surfaces are positioned within the yz plane. Both the three-phase AC power line 5 and the common mode current return line 6 pass through the first core 8a and the second core 8b. On the other hand, only the three-phase AC power line 5 of the three-phase AC power line 5 and the common mode current return line 6 passes through the third core 8c. The reason for this configuration will be described later.

[0021] The three-phase AC power line 5 is made up of electric wirings 5a, 5b, and 5c. For example, the electric wiring 5a is a U-phase electric wiring, the electric wiring 5b is a V-phase electric wiring, and the electric wiring 5c ​​is a W-phase electric wiring.

[0022] 1 and 3 show an example of a configuration in which each of the cores is composed of one first core 8a, one second core 8b, and one third core 8c, but the number of the first core 8a, the second core 8b, and the third core 8c may be two or more. Also, in FIG. 3, the cores are formed in a circular ring shape, but the shape is not limited to this. Each core may be formed in a square ring shape. Also, when each core is formed in a square ring shape, the four corners of each core may be chamfered.

[0023] The magnetic core 8 may be made of, for example, ferrite or amorphous. Parameters such as the outer periphery length, inner periphery length, thickness, aspect ratio, etc. of each core constituting the magnetic core 8 may be appropriately selected according to the capacity of the three-phase inverter 4 and the length, thickness, arrangement, etc. of the three-phase AC power line 5. Furthermore, the magnetic permeability of the magnetic core 8 may be appropriately selected according to the switching frequency, and the stray capacitance between the power conversion device 50 and the propulsion motor 15 and the ground.

[0024] Next, the effect of using the magnetic core 8 provided in the power conversion device 50 according to the first embodiment will be described with reference to Fig. 4. Fig. 4 is a diagram for explaining the effect of using the magnetic core 8 provided in the power conversion device 50 according to the first embodiment.

[0025] In FIG. 4, a zero-phase current flows in the three-phase AC power line 5 from the left to the right of the page, and a zero-phase current flows in the common mode current return line 6 from the right to the left of the page. At this time, a magnetic flux 100 shown by a two-dot chain line is generated in the first core 8a, the second core 8b, and the third core 8c through which the three-phase AC power line 5 passes, according to the right-hand screw rule. Also, a magnetic flux 110 shown by a one-dot chain line is generated in the first core 8a and the second core 8b through which the common mode current return line 6 passes. In the first core 8a and the second core 8b, the magnetic flux 100 and the magnetic flux 110 are in the opposite directions to each other, so they cancel each other out, and the magnetic flux density inside the first core 8a and the second core 8b becomes smaller. This makes it possible to significantly increase the level of zero-phase current at which the first core 8a and the second core 8b cause magnetic saturation, compared to the case where only the three-phase AC power line 5 is passed through the first core 8a and the second core 8b.

[0026] Next, the reason why the common mode current return line 6 is not passed through the third core 8c will be explained. In the above, it has been explained that the zero-phase current flows in the three-phase AC power line 5 from the left side to the right side of the paper, and the zero-phase current flows in the common mode current return line 6 from the right side to the left side of the paper. On the other hand, there is also an operation mode in which the current flows in the common mode current return line 6 in the same direction as the current flowing in the three-phase AC power line 5 and returns through the ground wire 7. Although the current in this operation mode is smaller than the zero-phase current, it is a current in the direction in which the magnetic flux is added, so it affects the magnetic flux density inside the magnetic core 8. In order to reduce this effect, the third core 8c is configured not to pass through the common mode current return line 6. This configuration can prevent the impedance of the return loop of the common mode current return line 6 from becoming extremely small compared to the impedance of the return loop of the ground circuit including the ground wire 7. This has the effect of preventing an increase in the zero-phase current while reducing the leakage current.

[0027] Next, another effect provided by the magnetic core 8 of the first embodiment will be described with reference to Figs. 5 to 7 showing configuration examples and results of electromagnetic field analysis performed on a configuration having the magnetic core 8 of the first embodiment. Fig. 5 is a diagram showing a configuration example of the magnetic core according to the first embodiment used in the electromagnetic field analysis. Fig. 6 is a diagram showing a configuration example of a magnetic core shown as a comparative example to Fig. 5. Fig. 7 is a diagram for explaining the electromagnetic field analysis performed on the magnetic core having the configuration of Figs. 5 and 6.

[0028] FIG. 5 shows a configuration example in which the number of first cores 8a and second cores 8b through which both the three-phase AC power line 5 and the common mode current return line 6 pass is two, and the number of third cores 8c through which only the three-phase AC power line 5 passes is four. The first cores 8a, the second cores 8b, and the third cores 8c are made of core members of the same structure. Each core member is made of a rectangular ring-shaped member as shown in the upper part of FIG. 7, and has a width of 150 mm in the z direction. In FIG. 7, the z axis direction is shown in the opposite direction to that in FIG. 3 and FIG. 4.

[0029] In addition, in the comparative example shown in FIG. 6 , the total number of core members is the same, 8, but the number of core members through which only the three-phase AC power lines 5 pass and the number of core members through which both the three-phase AC power lines 5 and the common mode current return line 6 pass are evenly set to 4.

[0030] The middle and lower parts of FIG. 7 show the results of the electromagnetic field analysis. The horizontal axis represents the position in the z direction, and the vertical axis represents the magnitude of the magnetic field. In the case of the configuration of FIG. 5, the core member to be analyzed is the core member 90 located at the outermost end of the first core 8a. In the case of the configuration of FIG. 6, the core member to be analyzed is the core member 92 located at the outermost end of the four magnetic cores through which only the three-phase AC power line 5 penetrates. The middle part of FIG. 7 shows the magnetic field distribution on the line A-A' in the magnetic core, and the lower part shows the magnetic field distribution on the line B-B' in the magnetic core. In both figures, the thick solid line represents the magnetic field distribution in the configuration of the comparative example, and the thin solid line represents the magnetic field distribution in the configuration of the first embodiment. 7, an AC current with an amplitude of 70 / 3 [A] and a frequency of 100 kHz is applied to the three electrical wirings in the three-phase AC power line 5, and an AC current with an amplitude of 70 [A] and a frequency of 100 kHz is applied to the common mode current return line 6. The relative permeability of the core member is set to 4000.

[0031] As shown in the analysis results in the middle part of Fig. 7, it can be seen that in the configuration of the first embodiment, the peak value of the magnetic field on line A-A' is reduced by about 100 (A / m) compared to the configuration of the comparative example. Also, as shown in the analysis results in the lower part of Fig. 7, it can be seen that in the configuration of the first embodiment, the peak value of the magnetic field on line B-B' is reduced by about 130 to 140 (A / m) compared to the configuration of the comparative example. Also, as shown in the analysis results in the middle and lower parts of Fig. 7, it can be seen that in the case of the first embodiment, the magnitude of the magnetic field is lower than that of the comparative example in most regions in the z-axis direction.

[0032] Next, a description will be given of the reason why the analysis result shown in Fig. 7 is obtained. Fig. 8 is a diagram for explaining the reason why the analysis result shown in Fig. 7 is obtained.

[0033] When the three-phase AC power line 5 is drawn from the power conversion device 50, the three-phase AC power line 5 may be connected to a terminal block as a relay point of wiring with the outside for the purpose of fixing or insulation, as shown in FIG. 8. When the power conversion device 50 is configured for a railway vehicle, the three-phase AC power line 5 is often flat, and the electric wiring of each phase is often arranged at a distance in the terminal block. In this case, a part of the electric wiring of each phase is bent and drawn out from the magnetic core 8 when drawing it into the terminal block. There are cases where the magnetic flux of the bent and drawn out electric wiring remains without being canceled out, and generates a local magnetic flux around the magnetic core 8. FIG. 8 shows a situation in which the electric wiring of each phase drawn out from the magnetic core arranged at the outermost end is loosened, generating a local magnetic flux.

[0034] 5 and 6, in the core members 90 and 92 to be analyzed that are located at the outermost ends, the flat three-phase AC power line 5 is bent and drawn out. Therefore, local magnetic flux is generated in the core members 90 and 92. Here, in the core member 90 in FIG. 5 through which the common mode current return line 6 passes, a part of the local magnetic flux is cancelled out by the magnetic flux due to the current flowing through the common mode current return line 6. In contrast, in the core member 92 in FIG. 6 through which the common mode current return line 6 does not pass, the local magnetic flux remains without being cancelled out. Therefore, it is considered that the magnetic field of the core member 90 in the configuration of the first embodiment is smaller than that of the core member 92 in the configuration of the comparative example.

[0035] Therefore, by using the magnetic core 8 of the first embodiment, it is possible to suppress an increase in the magnetic field inside the magnetic core 8, thereby making it possible to reduce the probability of magnetic saturation occurring. In addition, by using the magnetic core 8 of the first embodiment, it is possible to reduce the probability of magnetic saturation occurring, thereby making it possible to suppress a decrease in the magnetic permeability of the magnetic core 8 caused by magnetic saturation.

[0036] As described above, the power conversion device for a railway vehicle according to the first embodiment includes a three-phase inverter that converts DC power into AC power for a propulsion motor mounted on the railway vehicle, and a magnetic core through which a three-phase AC power line and a common mode current return line pass. The three-phase AC power line is an electric wiring that connects the three-phase inverter and the propulsion motor, and the common mode current return line is an electric wiring that connects between the ground potential of the power conversion device and the ground potential of the propulsion motor. The magnetic core has a first and a second core through which both the three-phase AC power line and the common mode current return line pass, and a third core through which only the three-phase AC power line passes. The first core is disposed on the side of the three-phase inverter, the second core is disposed on the side of the propulsion motor, and the third core is disposed between the first core and the second core.

[0037] As described above, the power conversion device for railway vehicles according to the first embodiment has first and second cores through which both the three-phase AC power lines and the common mode current return line pass, and has a third core between the first and second cores through which only the three-phase AC power lines of the three-phase AC power lines and the common mode current return line pass. This configuration makes it possible to prevent the impedance of the return loop of the common mode current return line from becoming extremely small compared to the impedance of the return loop of the ground circuit including the ground line. As a result, the power conversion device according to the first embodiment can reduce the leakage current while preventing an increase in the zero-phase current.

[0038] As described above, the power conversion device for railway vehicles according to the first embodiment is configured such that the first and second cores, through which both the three-phase AC power lines and the common mode current return line pass, are disposed on both ends of the third core, through which only the three-phase AC power lines pass. With this configuration, it is possible to suppress an increase in the magnetic field of the core members located at the outermost ends of the first and second cores, thereby reducing the probability of magnetic saturation occurring in the magnetic cores and suppressing a decrease in the magnetic permeability of the magnetic cores due to magnetic saturation.

[0039] Embodiment 2 In the second embodiment, a configuration for further reducing the local magnetic flux described in the first embodiment will be described.

[0040] FIG. 9 is a diagram showing a state in which the local magnetic flux described in the first embodiment is generated on the configuration diagram of magnetic core 8 in FIG.

[0041] 9 shows a state in which the electric wirings 5a and 5c of the three electric wirings 5a, 5b, and 5c constituting the three-phase AC power line 5 are not parallel to the electric wiring 5b when they are drawn from the first core 8a to the first surface side. Also, in FIG. 9, the electric wirings 5a and 5c of the three electric wirings 5a, 5b, and 5c constituting the three-phase AC power line 5 are not parallel to the electric wiring 5b when they are drawn from the second core 8b to the second surface side. In FIG. 9, the same elements as those in FIG. 4 are denoted by the same reference numerals.

[0042] 9 also shows magnetic flux 100 generated by the current flowing through the three-phase AC power line 5, magnetic flux 110 generated by the current flowing through the common mode current return line 6, and local magnetic flux 120 that may be generated by the portions of the electric wiring 5a, 5c that are not parallel to the electric wiring 5b, shown by dashed lines. As described above, the magnetic flux 100 and the magnetic flux 110 are in the opposite directions to each other, so they cancel each other out. In contrast, there is no canceling magnetic flux for the local magnetic flux 120, so its components remain around the first core 8a and the second core 8b, or enter the inside of the first core 8a and the second core 8b.

[0043] Therefore, in the second embodiment, a configuration of a magnetic core 81 shown in Fig. 10 is proposed. Fig. 10 is a diagram for explaining the configuration of a magnetic core 81 provided in a power conversion device 50 according to the second embodiment. In Fig. 10, the same elements as those in Fig. 9 are denoted by the same reference numerals.

[0044] In the magnetic core 81 of the second embodiment, as shown in Fig. 10, a non-magnetic metal plate 200 is provided on a first surface of the first core 8a, and a non-magnetic metal plate 200 is also provided on a second surface of the second core 8b. An example of the non-magnetic metal plate 200 is an aluminum plate.

[0045] 10, the non-magnetic metal plate 200 is disposed on the yz plane of the first core 8a and the second core 8b, and therefore interlinks with the local magnetic flux 120. When the local magnetic flux 120 interlinks with the non-magnetic metal plate 200, an eddy current flows in the non-magnetic metal plate 200. This eddy current generates a magnetic flux in a direction that cancels out the local magnetic flux 120, and therefore acts to prevent the local magnetic flux 120 from entering the inside of the first core 8a and the second core 8b. This makes it possible to prevent the magnetic core 81 from becoming magnetically saturated by the local magnetic flux 120.

[0046] When the power conversion device 50 is for a railway vehicle, the side of the traction motor 15 has greater dimensional constraints than the side of the three-phase inverter 4, and there is often less free space. For this reason, a preferred embodiment is to install the nonmagnetic metal plate 200 on the second surface of the second core 8b. In addition, when a flat three-phase AC power line 5 is used, it is difficult to pull out all of the three electric wirings 5a, 5b, and 5c that constitute the three-phase AC power line 5 in parallel with each other and fix them to the terminal block. For this reason, it goes without saying that a more preferred embodiment is to install the nonmagnetic metal plate 200 on the first surface of the first core 8a on the three-phase inverter 4 side as well.

[0047] 10 shows an example in which two of the three electric wirings 5a, 5b, and 5c are not parallel to the other electric wiring 5b, but the present invention is not limited to this example. Even if, for example, one electric wiring 5a of the three electric wirings 5a, 5b, and 5c is not parallel to the other two electric wirings 5b and 5c, the effect of reducing the local magnetic flux 120 can be obtained by installing the nonmagnetic metal plate 200. That is, when at least one of the three electric wirings 5a, 5b, and 5c constituting the three-phase AC power line 5 is drawn from the first core 8a to the first surface side or from the second core 8b to the second surface side, the effect of reducing the local magnetic flux 120 by the nonmagnetic metal plate 200 can be obtained as long as the electric wiring is drawn so as not to be parallel to the other one or two electric wirings.

[0048] Embodiment 3 In the third embodiment, a preferred thickness of the nonmagnetic metal plate 200 in the magnetic core 81 configured as shown in Fig. 10 will be described. Specifically, in the power conversion device 50 according to the third embodiment, it is proposed that the thickness of the nonmagnetic metal plate 200 in the magnetic core 8 is set to be equal to or greater than the skin depth.

[0049] The skin depth in a metal plate is the distance at which an electromagnetic field incident on a certain metal material attenuates to 1 / e (≒1 / 2.718≒-8.7 dB). If the magnetic permeability of the nonmagnetic metal plate 200 is μ, the electrical conductivity is σ, and the frequency is f, then the skin depth δ is given by δ=1 / √(πfμσ).

[0050] In the non-magnetic metal plate 200 of the magnetic core 81, if the thickness is set to be equal to or greater than the skin depth of the material of the non-magnetic metal plate 200, the amount of magnetic flux entering the first core 8a and the second core 8b can be reduced to 1 / e or less compared to the case where there is no non-magnetic metal plate 200. This makes it possible to configure the magnetic core 81 in a manner that makes magnetic saturation less likely to occur.

[0051] Embodiment 4 FIG. 11 is a diagram for explaining the configuration of the magnetic core 82 provided in the power conversion device 50 according to the fourth embodiment. In the magnetic core 82 shown in FIG. 11, a fourth core 8d through which only the three-phase AC power line 5 passes is added between the first core 8a and the third core 8c in the configuration of the magnetic core 81 shown in FIG. 10. In addition, in the magnetic core 82 shown in FIG. 11, a fifth core 8e through which only the three-phase AC power line 5 passes is added between the second core 8b and the third core 8c. In addition, in the magnetic core 82 shown in FIG. 11, non-magnetic metal plates 300 are installed on the second surface of the first core 8a, the first surface of the fourth core 8d, the second surface of the fifth core 8e, and the first surface of the second core 8b. An example of the non-magnetic metal plate 300 is an aluminum plate. In the configuration of Fig. 11, the nonmagnetic metal plate 200 shown in Fig. 10 is not provided on the first surface of the first core 8a and the second surface of the second core 8b, but the nonmagnetic metal plate 200 may be provided as in Fig. 10. The effect of including the nonmagnetic metal plate 200 is the same as in the second embodiment.

[0052] Next, the effect of using the non-magnetic metal plate 300 will be described. First, the common mode current return line 6 does not pass through the fourth core 8d, the third core 8c, and the fifth core 8e, so it is bent between the first core 8a and the fourth core 8d and between the fifth core 8e and the second core 8b, as shown by the broken lines, and wired inside the magnetic core 82. Due to this wiring form, local magnetic fluxes as described in the second embodiment are generated at the bent portions. In the fourth embodiment, the non-magnetic metal plate 300 is installed to prevent such local magnetic fluxes from entering the first core 8a and the fourth core 8d, and the fifth core 8e and the second core 8b. By installing the non-magnetic metal plate 300, it is possible to prevent the magnetic core 82 from becoming magnetically saturated due to local magnetic fluxes that may be generated by the bent portions of the common mode current return line 6.

[0053] If the thickness of the non-magnetic metal plate 300 is set to be equal to or greater than the skin depth of the material of the non-magnetic metal plate 200, the same effect as in the third embodiment can be obtained. In addition, in FIG. 11, the non-magnetic metal plate 300 is provided on each of the second surface of the first core 8a, the first surface of the fourth core 8d, the second surface of the fifth core 8e, and the first surface of the second core 8b, but this configuration is not limited to this. If the distance between the first core 8a and the fourth core 8d is wider than the thickness of the non-magnetic metal plate 300, the non-magnetic metal plate 300 may be provided only on the surface of the common mode current return line 6 near the bent portion. For example, if the bent portion of the common mode current return line 6 is closer to the first surface of the fourth core 8d than to the second surface of the first core 8a, the non-magnetic metal plate 300 may be provided only on the first surface of the fourth core 8d. Similarly, for example, if the bent portion of the common mode current return line 6 is closer to the second surface of the fifth core 8e than to the first surface of the second core 8b, the non-magnetic metal plate 300 may be placed only on the second surface of the fifth core 8e.

[0054] Embodiment 5. FIG. 12 is a diagram for explaining the configuration of a magnetic core 83 provided in a power conversion device 50 according to the fifth embodiment. In the magnetic core 83 shown in FIG. 12, the common mode current return line 6 shown in FIG. 10 is divided into two common mode current return lines 6a and 6b, which pass through the first core 8a and the second core 8b. The common mode current return line 6a, which is one of the two divided lines, is arranged so as to be parallel to the electric wiring 5a. The common mode current return line 6b, which is the other of the two divided lines, is arranged so as to be parallel to the electric wiring 5c. Note that "parallel" here does not mean only parallel in the strict sense, but means that it is sufficient if it is substantially parallel.

[0055] Next, the effect of the magnetic core 83 of the fifth embodiment will be described. In FIG. 12, the electric wirings 5a, 5b, and 5c carry the same-phase zero-phase currents indicated by the dashed-dotted arrows. On the other hand, the common mode current return lines 6a and 6b carry the same-phase currents indicated by the dashed-dotted arrows, which are opposite in phase to the zero-phase currents flowing through the electric wirings 5a, 5b, and 5c. Therefore, the magnetic flux indicated by the solid line generated by the current flowing through the electric wiring 5a and the magnetic flux indicated by the dashed line generated by the current flowing through the common mode current return line 6a are opposite in direction to each other and cancel each other out. Similarly, the magnetic flux indicated by the solid line generated by the current flowing through the electric wiring 5c ​​and the magnetic flux indicated by the dashed line generated by the current flowing through the common mode current return line 6b are opposite in direction to each other and cancel each other out. As a result, even when the electric wiring 5a is bent and drawn out from the first core 8a and the second core 8b, the common mode current return line 6a arranged parallel to the electric wiring 5a suppresses the generation of local magnetic flux, and it is possible to prevent the magnetic flux from entering the inside of the magnetic core 83. Also, even when the electric wiring 5c ​​is bent and drawn out from the first core 8a and the second core 8b, the common mode current return line 6b arranged parallel to the electric wiring 5c ​​suppresses the generation of local magnetic flux, and it is possible to prevent the magnetic flux from entering the inside of the magnetic core 83.

[0056] In the configuration of Fig. 12, the non-magnetic metal plate 200 is not provided, but the non-magnetic metal plate 200 may be provided on the first surface of the first core 8a and the second surface of the second core 8b as shown in Fig. 10. In the fifth embodiment, the common mode current return line 6a, which is one of the two divided lines, is arranged parallel to the electric wiring 5a, which is the first electric wiring of the three electric wirings 5a, 5b, and 5c, and the other common mode current return line 6b is arranged parallel to the electric wiring 5c, which is the second electric wiring of the three electric wirings 5a, 5b, and 5c, as applied to the configuration of Fig. 10, but it may be applied to the configuration of Fig. 11 according to the fourth embodiment. If applied to the configuration of Fig. 11, the effect described in the fourth embodiment can also be obtained.

[0057] The configurations shown in the above embodiments are merely examples, and may be combined with other known technologies, or the embodiments may be combined with each other. Also, parts of the configurations may be omitted or modified without departing from the spirit of the invention. Various aspects of the present disclosure are summarized below as appendices. [Appendix 1] A power conversion device for a railway vehicle for driving a propulsion motor mounted on the railway vehicle, comprising: a three-phase inverter that converts DC power into AC power for the traction motor; a magnetic core through which a three-phase AC power line, which is an electrical wiring that connects the three-phase inverter and the propulsion motor, and a common mode current return line, which is an electrical wiring that connects between the ground potential of the power conversion device and the ground potential of the propulsion motor, pass; Equipped with The magnetic core is a first core disposed on the side of the three-phase inverter and through which both the three-phase AC power lines and the common mode current return line pass; a second core disposed on the side of the traction motor and through which both the three-phase AC power line and the common mode current return line pass; a third core disposed between the first core and the second core and through which only the three-phase AC power line passes; Equipped with In each of the first, second and third cores, a surface facing the three-phase inverter side is defined as a first surface, and a surface facing the traction motor side is defined as a second surface, At least one of the three electric wirings constituting the three-phase AC power line is drawn out from the second core to the second surface side so as not to be parallel to the other one or two electric wirings. 2. A power conversion device for a railway vehicle. [Appendix 2] The first, second and third cores are formed in a square or circular ring shape, A non-magnetic metal plate is provided on the second surface of the second core. 2. A power conversion device for a railway vehicle as described in claim 1. [Appendix 3] A non-magnetic metal plate is provided on the first surface of the first core. 3. A power conversion device for a railway vehicle according to claim 1 or 2. [Appendix 4] At least one of the three electric wirings constituting the three-phase AC power line is drawn out from the first core to the first surface side so as not to be parallel to the other one or two electric wirings. 4. A power conversion device for a railway vehicle as described in claim 3. [Appendix 5] a fourth core disposed between the first core and the third core and through which only the three-phase AC power line passes; a fifth core disposed between the second core and the third core and through which only the three-phase AC power line passes; Equipped with The fourth and fifth cores are formed in a square or circular ring shape, In each of the fourth and fifth cores, a surface facing the three-phase inverter side is defined as a third surface, and a surface facing the traction motor side is defined as a fourth surface. A non-magnetic metal plate is provided on each of the fourth surface of the first core, the third surface of the fourth core, the fourth surface of the fifth core, and the third surface of the second core. 5. A power conversion device for a railway vehicle according to any one of claims 2 to 4. [Appendix 6] The non-magnetic metal plate is formed to have a thickness equal to or greater than the skin depth. 6. A power conversion device for a railway vehicle according to any one of claims 2 to 5. [Appendix 7] The common mode current return line is divided into two and passes through the first and second cores. 7. A power conversion device for a railway vehicle according to any one of claims 1 to 6. [Appendix 8] one of the two divided common mode current return lines is arranged parallel to a first electrical wiring which is one of three electrical wirings constituting the three-phase AC power line; The other of the two divided common mode current return lines is arranged in parallel to a second electrical wiring different from the first electrical wiring among the three electrical wirings constituting the three-phase AC power line. 8. A power conversion device for a railway vehicle as described in claim 7. [Explanation of symbols]

[0058] 2,2A input circuit section, 3 filter capacitor, 4 three-phase inverter, 4a switching element, 5 three-phase AC power line, 5a,5b,5c electrical wiring, 6,6a,6b common mode current return line, 7 grounding line, 8,81,82,83 magnetic core, 8a first core, 8b second core, 8c third core, 8d fourth core, 8e fifth core, 10 overhead line, 11 current collector, 12 rail, 13 wheel, 15 traction motor, 21 main transformer, 22 converter, 50 power conversion device, 90,92 core member, 100,110 magnetic flux, 120 local magnetic flux, 200,300 non-magnetic metal plate.

Claims

1. A power conversion device for a railway vehicle for driving a propulsion motor mounted on the railway vehicle, comprising: a three-phase inverter that converts DC power into AC power for the traction motor; a magnetic core through which a three-phase AC power line, which is an electrical wiring that connects the three-phase inverter and the propulsion motor, and a common mode current return line, which is an electrical wiring that connects between the ground potential of the power conversion device and the ground potential of the propulsion motor, pass; Equipped with The magnetic core is a first core disposed on the side of the three-phase inverter and through which both the three-phase AC power lines and the common mode current return line pass; a second core disposed on the side of the traction motor and through which both the three-phase AC power line and the common mode current return line pass; a third core disposed between the first core and the second core and through which only the three-phase AC power line passes; Equipped with In each of the first, second and third cores, a surface facing the three-phase inverter side is defined as a first surface, and a surface facing the traction motor side is defined as a second surface, At least one of the three electric wirings constituting the three-phase AC power line is drawn out from the second core to the second surface side so as not to be parallel to the other one or two electric wirings.

2. A power conversion device for a railway vehicle.

2. The first, second and third cores are formed in a square or circular ring shape, A non-magnetic metal plate is provided on the second surface of the second core.

2. The power conversion device for a railway vehicle according to claim 1.

3. A non-magnetic metal plate is provided on the first surface of the first core.

2. The power conversion device for a railway vehicle according to claim 1.

4. At least one of the three electric wirings constituting the three-phase AC power line is drawn out from the first core to the first surface side so as not to be parallel to the other one or two electric wirings.

4. The power conversion device for a railway vehicle according to claim 3.

5. a fourth core disposed between the first core and the third core and through which only the three-phase AC power line passes; a fifth core disposed between the second core and the third core, through which only the three-phase AC power line passes; Equipped with The fourth and fifth cores are formed in a square or circular ring shape, In each of the fourth and fifth cores, a surface facing the three-phase inverter is defined as a third surface, and a surface facing the traction motor is defined as a fourth surface. A non-magnetic metal plate is provided on each of the fourth surface of the first core, the third surface of the fourth core, the fourth surface of the fifth core, and the third surface of the second core.

3. The power conversion device for a railway vehicle according to claim 2.

6. The non-magnetic metal plate is formed to have a thickness equal to or greater than the skin depth.

3. The power conversion device for a railway vehicle according to claim 2.

7. The common mode current return line is divided into two and passes through the first and second cores.

7. The power conversion device for a railway vehicle according to claim 1.

8. one of the two divided common mode current return lines is arranged parallel to a first electrical wiring which is one of three electrical wirings constituting the three-phase AC power line; The other of the two divided common mode current return lines is arranged parallel to a second electrical wiring different from the first electrical wiring among the three electrical wirings constituting the three-phase AC power line.

8. The power conversion device for a railway vehicle according to claim 7.

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