Railway wagon performance conversion device

Abstract

A power conversion device (50) includes: a three-phase inverter (4) that converts direct current power into alternating current power for a drive motor (15); and a magnetic core (8). The magnetic core (8) includes: first and second cores (8a, 8b) through which both a three-phase alternating current power line (5) and a direct current circulating line (6) are passed; and a third core (8c) through which only the three-phase alternating current power line (5) is passed. The first core (8a) is arranged on a side closer to the three-phase inverter (4), the second core (8b) is arranged on a side closer to the drive motor (15), and the third core (8c) is arranged between the first core (8a) and the second core (8b).In the first, second, and third cores (8a to 8c), when at least one of the three electrical conductors in the three-phase alternating current power line (5) is led out from the second core (8b) in the direction of the drive motor (15), the at least one of the three electrical conductors is not parallel to the remaining one or the remaining two electrical conductors.

Description

Area

[0001] The present disclosure relates to a railway car power conversion device for driving a traction motor installed in a railway car. background

[0002] A power conversion device includes a switching element such as an insulated-gate bipolar transistor (IGBT) or a metal-oxide-semiconductor field-effect transistor (MOSFET). In recent years, power conversion devices have increased their switching voltage and speed along with the increase in the breakdown voltage and switching frequency of switching elements.

[0003] It is well known that a switching operation performed in a power conversion device causes a common-mode current, which is a zero-phase current. It is also known that a switching operation performed in a power conversion device causes a leakage current flowing through a parasitic capacitance located between ground and an AC line connecting the power conversion device to a load. In addition, it is also known that a switching operation performed in a power conversion device causes a leakage current flowing through a parasitic capacitance located between an AC line and a casing housing the power conversion device, with the leakage current flowing to a peripheral device that is not a load. These leakage currents are to be distinguished from zero-phase currents because they are common-mode currents that flow through a grounding system.

[0004] As described above, increasing the switching voltage and switching speed leads to an increase in zero-phase current and leakage current, as well as an increase in radiated noise and conducted noise. Therefore, there is a problem that increasing the switching voltage and switching speed adversely affects peripheral communication devices and the like.

[0005] To reduce zero-phase current, conventional techniques wind AC lines around or pass through the same magnetic core. In addition, Patent Literature 1 below discloses a technique in which, to reduce leakage current, a ground terminal of a power conversion device and a ground terminal of a load are connected by an electrical conductor called a common-mode current circulation line, and AC lines and the common-mode current circulation line are wound around or pass through the same magnetic core. Citation listPatent literature

[0006] Patent Literature 1: Japanese Patent Application Laid-Open No. 2001-086734 Brief description of the inventionProblem to be solved by the invention

[0007] When the technique of Patent Literature 1 is used, the impedance of a circulation path of a ground circuit is larger than the impedance of a circulation path of the common-mode current circulation line. Therefore, the leakage current flowing through the circulation path of the ground circuit can be reduced. However, it is described that when the technique of Patent Literature 1 is used, a peak value of the zero-phase current is larger than in a configuration in which only the AC lines are wound around the same magnetic core or passed through the same magnetic core. As described above, zero-phase current causes radiated noise and conducted noise. In the case of a railway car power conversion device, an increase in the zero-phase current cannot be tolerated because an extremely large current flows through a drive motor serving as a load.

[0008] The present disclosure has been made in consideration of the foregoing, and an object of the present disclosure is to provide a railway car power conversion device capable of reducing leakage current while preventing an increase in zero-phase current. Means of solving the problem

[0009] To solve the above-described problem and achieve the objective, a railway car power conversion device according to the present disclosure is a railway car power conversion device for driving a traction motor installed in a railway car, the railway car power conversion device comprising: a three-phase inverter that converts DC power into AC power for the traction motor; and a magnetic core penetrated by a three-phase AC power line and a common-mode current circulation line. The three-phase AC power line is an electrical conductor connecting the three-phase inverter and the traction motor. The common-mode current circulation line is an electrical conductor connecting a ground potential of the power conversion device and a ground potential of the traction motor.The magnetic core includes first and second cores penetrated by both the three-phase AC power line and the common-mode current circulation line; and a third core penetrated only by the three-phase AC power line. The first core is disposed on a side closer to the three-phase inverter, and the second core is disposed on a side closer to the drive motor. Furthermore, the third core is disposed between the first core and the second core.Assuming that in each of the first core, the second core, and the third core, a first surface is defined as a surface facing the three-phase inverter and a second surface is defined as a surface facing the drive motor, when at least one of three electrical conductors included in the three-phase AC power line is led out of the second core toward the second surface, the at least one of the three electrical conductors is not parallel to the remaining one or two electrical conductors. Effects of the invention

[0010] The railway car power conversion device according to the present disclosure has the advantage that the leakage current can be reduced while preventing an increase in the zero-phase current. Short description of the drawings Fig. 1 is a diagram showing an exemplary configuration of an electrical system of a railway car system including a power conversion device according to a first embodiment. Fig. 2 is a diagram showing an exemplary variant of a Fig. 1 shows the input circuit unit. Fig. 3 is a diagram for describing a configuration of a magnetic core included in the power conversion device according to the first embodiment and a positional relationship between a three-phase AC power line and a common-mode current circulation line. Fig. 4 is a diagram for describing an effect to be achieved in the case of using the magnetic core included in the power conversion device according to the first embodiment. Fig. 5 is a diagram showing an exemplary configuration of the magnetic core according to the first embodiment used in an electromagnetic field analysis. Fig. 6 is a diagram showing an exemplary configuration of a magnetic core used as a comparative example for comparison with the magnetic core shown in Fig. 5 shown configuration is used. Fig. Figure 7 is a diagram describing an electromagnetic field analysis performed on the magnetic cores arranged as shown in Fig. 5 and Fig. 6 are configured. Fig. 8 is a diagram to describe the reason why the Fig. The analysis results presented in Figure 7 were obtained. Fig. Fig. 9 is a diagram showing a situation in which a local magnetic flux is generated according to the first embodiment, in a configuration diagram of the magnetic core of Fig. 4. Fig. 10 is a diagram for describing a configuration of a magnetic core included in a power conversion device according to a second embodiment. Fig. 11 is a diagram for describing a configuration of a magnetic core included in a power conversion device according to a fourth embodiment. Fig. 12 is a diagram for describing a configuration of a magnetic core included in a power conversion device according to a fifth embodiment. Description of the embodiments

[0011] Railway car power conversion devices (hereinafter, optionally abbreviated to "power conversion devices") according to embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Note that, for ease of understanding, the reduction scale of each element in the accompanying drawings may differ from the actual scale. The reduction scale of each element may also differ between the drawings. Furthermore, in the following description, physical connection and electrical connection are uniformly referred to as "connection" without distinguishing between them. That is, the term "connection" refers to both a direct connection between constituent elements and an indirect connection between constituent elements via another constituent element. First embodiment.

[0012] Fig. Figure 1 is a diagram showing an exemplary configuration of an electrical system of a railway car system including a power conversion device 50 according to a first embodiment. The power conversion device 50 according to the first embodiment includes a film capacitor 3, a three-phase inverter 4, and a magnetic core 8. Fig. 1, an input circuit unit 2 is connected to an input end of the three-phase inverter 4, and at least one drive motor 15 is connected to an output end of the three-phase inverter 4. The drive motor 15 is a three-phase motor that applies a driving force to a railway car.

[0013] The input circuit unit 2 includes at least one switch and a filter reactor. One end of the input circuit unit 2 is connected to an overhead line 10 via a pantograph 11, and the other end is connected to a rail 12, which represents a ground potential, via a wheel 13. DC power or AC power supplied from the overhead line 10 is applied to one end of the input circuit unit 2 via the pantograph 11. A DC voltage generated by the DC power at an output end of the input circuit unit 2 is applied to the three-phase inverter 4. The film capacitor 3 smoothes the DC voltage applied to the three-phase inverter 4 to reduce ripple of the DC voltage. The three-phase inverter 4 converts the DC power supplied via the input circuit unit 2 into AC power for the drive motor 15.

[0014] The three-phase inverter 4 is connected to the drive motor 15 via the magnetic core 8 through a three-phase AC power line 5. The three-phase AC power line 5 is an electrical conductor that connects the three-phase inverter 4 and the drive motor 15. A casing (not shown) of the drive motor 15 is grounded via a grounding conductor 7. In addition, the drive motor 15 is connected to a portion serving as a ground potential of the power conversion device 50 via a common-mode current circulation line 6. The common-mode current circulation line 6 is an electrical conductor that electrically connects the ground potential of the power conversion device 50 to a ground potential of the drive motor 15.

[0015] The three-phase inverter 4 includes a plurality of switching elements 4a in a three-phase bridge circuit. Each switching element 4a includes an anti-parallel-connected freewheeling diode. Each switching element 4a performs a switching operation according to a gate control signal output from a control unit (not shown). The current flowing through each switching element 4a is intermittently controlled by the switching operation of the switching element 4a. As a result, the DC power supplied from the input circuit unit 2 is converted into AC power for the drive motor 15. The drive motor 15 is driven by the AC power supplied from the three-phase inverter 4 and exerts a driving force on a train including one or more railway cars (not shown).The three-phase inverter 4 drives the drive motor 15 by converting the DC power supplied via the input circuit unit 2 into AC power for the drive motor 15. It should be noted that although the input circuit unit 2 and the three-phase inverter 4 are shown in . Fig. 1 are shown as separate constitutional elements, the input circuit unit 2 and the three-phase inverter 4 can be accommodated in the same housing.

[0016] Fig. 2 is a diagram showing an exemplary variant of the Fig. 1 shows the input circuit unit 2. Fig. 2 shows an input circuit unit 2A as an example of a case where 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 an AC voltage received via the pantograph 11 and applies the stepped-down AC voltage to the converter 22. The converter 22 converts the stepped-down AC voltage into a DC voltage and applies the DC voltage to the three-phase inverter 4.

[0017] Hereinafter, a configuration and a connection form of the magnetic core 8 will be described with reference to Fig. 1 and Fig. 3 described. Fig. 3 is a diagram for describing a configuration of the magnetic core 8 included in the power conversion device 50 according to the first embodiment and a positional relationship between the three-phase AC power line 5 and the common-mode current circulation line 6.

[0018] The magnetic core 8 includes a first core 8a, a second core 8b, and a third core 8c. The first core 8a is disposed on a side closer to the three-phase inverter 4. The second core 8b is disposed on a side closer to the drive motor 15. The third core 8c is disposed between the first core 8a and the second core 8b. As shown in Fig. As shown in Figure 3, the first core 8a, the second core 8b, and the third core 8c are formed in a circular annular shape. It goes without saying that the term "circular" used herein refers not only to a perfectly circular shape, but also to an elliptical shape.

[0019] Furthermore, when a first surface is defined as a surface facing the three-phase inverter 4 and a second surface is defined as a surface facing the drive motor 15, each of the first core 8a, the second core 8b, and the third core 8c is arranged such that the first and second surfaces are located on a yz plane. Moreover, both the three-phase AC power line 5 and the common-mode current circulation 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 among the three-phase AC power line 5 and the common-mode current circulation line 6 passes through the third core 8c. The reason for such a configuration will be described below.

[0020] The three-phase AC power line 5 includes electrical conductors, namely, electrical conductors 5a, 5b, and 5c. For example, electrical conductor 5a is a U-phase conductor, electrical conductor 5b is a V-phase conductor, and electrical conductor 5c is a W-phase conductor.

[0021] It should be noted that Fig. 1 and Fig. 3 each show a configuration in which the magnetic core 8 has a first core 8a, a second core 8b, and a third core 8c each once, however, the number of first cores 8a, the number of second cores 8b, and the number of third cores 8c may each be two or more. In addition, Fig. 3 illustrates a case where each core is formed in a circular annular shape, but the shape of each core is not limited to this. Each core may be formed in a rectangular annular shape. Furthermore, when each core is formed in a rectangular annular shape, four corners of each core may be chamfered.

[0022] For example, ferrite or amorphous material can be used as the material of the magnetic core 8. Furthermore, with respect to parameters such as the outer peripheral length, inner peripheral length, thickness, and aspect ratio of each core included in the magnetic core 8, appropriate values ​​can be used according to the capacity of the three-phase inverter 4 and the length, thickness, arrangement, and the like of the three-phase AC power line 5. Furthermore, with respect to the magnetic permeability of the magnetic core 8, appropriate values ​​can be selected depending on the switching frequency, a stray capacitance between the power conversion device 50 and the ground, a stray capacitance between the drive motor 15 and the ground, and the like.

[0023] An effect obtained in the case of using the magnetic core 8 included in the power conversion device 50 according to the first embodiment will be described below with reference to Fig. 4. Fig. 4 is a diagram for describing an effect obtained in the case of using the magnetic core 8 included in the power conversion device 50 according to the first embodiment.

[0024] Fig. 4 assumes that zero-phase current flows through the three-phase AC power line 5 in a direction from the left side to the right side in the drawing, and that zero-phase current flows through the common-mode current circulation line 6 in a direction from the right side to the left side in the drawing. At this time, magnetic fluxes 100, represented by double-dotted chain lines, are generated according to the right-hand screw rule in the first core 8a, the second core 8b, and the third core 8c, which are penetrated by the three-phase AC power line 5. In addition, magnetic fluxes 110, represented by alternating long and short chain lines, are generated in the first core 8a and the second core 8b, which are penetrated by the common-mode current circulation line 6. In the first core 8a and the second core 8b, the magnetic fluxes 100 and the magnetic fluxes 110 oppose each other.Therefore, the magnetic fluxes 100 and 110 cancel each other out. This reduces the magnetic flux density inside the first core 8a and the second core 8b. As a result, compared to a case where only the three-phase AC power line 5 penetrates the first core 8a and the second core 8b, it is possible to significantly increase the level of the zero-phase current at which magnetic saturation occurs in the first core 8a and the second core 8b.

[0025] The reason why the common-mode current circulation line 6 is not passed through the third core 8c is described below. Above, the description of the zero-phase current was given as follows: zero-phase current flows through the three-phase AC power line 5 in the direction from the left side to the right side in the drawing, and zero-phase current flows through the common-mode current circulation line 6 in the direction from the right side to the left side in the drawing. However, there is also an operation mode in which current flows through the common-mode current circulation line 6 in the same direction as the current flowing through the three-phase AC power line 5 and circulates via the grounding conductor 7. Although the current flowing in this operation mode is smaller than the zero-phase current, the current affects the magnetic flux density inside the magnetic core 8 because the current flows in a direction in which a magnetic flux is applied.To reduce this influence, the common-mode current circulation line 6 is not passed through the third core 8c. With this configuration, it is possible to prevent the impedance of a circulation path of the common-mode current circulation line 6 from becoming extremely smaller than the impedance of a circulation path of a ground circuit including the ground conductor 7. As a result, it is possible to achieve the effect of reducing the leakage current while preventing an increase in the zero-phase current.

[0026] Next, another effect achieved by the magnetic core 8 of the first embodiment will be described with reference to Fig. 5 to Fig. 7, which show an exemplary configuration, results and the like of an electromagnetic field analysis performed on the configuration including the magnetic core 8 of the first embodiment. Fig. 5 is a diagram showing an exemplary configuration of the magnetic core according to the first embodiment used in electromagnetic field analysis. Fig. 6 is a diagram showing an exemplary configuration of a magnetic core used as a comparative example for comparison with the magnetic core shown in Fig. 5 shown configuration. Fig. Figure 7 is a diagram describing an electromagnetic field analysis performed on the magnetic cores arranged as shown in Fig. 5 and Fig. 6 are configured.

[0027] Fig. 5 shows an exemplary configuration in which the number of first cores 8a and second cores 8b, which are penetrated by both the three-phase AC power line 5 and the common-mode current circulation line 6, is two each, and the number of third cores 8c, which are penetrated only by the three-phase AC power line 5, is four. Core elements with the same structure were used for the first core 8a, the second core 8b, and the third core 8c. A rectangular annular shape element, as shown in the upper part of Fig. 7 was used as each core element. The width of each core element was 150 mm in a z-direction. It should be noted that in Fig. 7 the direction of a z-axis opposite to that in Fig. 3 and Fig. 4 is.

[0028] In addition, Fig. 6, as a comparative example, an exemplary configuration in which the total number of core elements is also eight, and the number of core elements penetrated only by the three-phase AC power line 5 and the number of core elements penetrated by both the three-phase AC power line 5 and the common-mode current circulation line 6 are each set to four.

[0029] Results of an electromagnetic field analysis are shown in the middle and lower part of Fig. 7. The horizontal axis represents a position in the z-direction, and the vertical axis represents the magnitude of a magnetic field. In the case of the configuration of Fig. 5, a core element 90 was analyzed. The core element 90 is the outermost of the first cores 8a. Furthermore, in the case of the configuration of Fig. 6, a core element 92 is analyzed. The core element 92 is the outermost of the four magnetic cores, which are only penetrated by the three-phase AC power line 5. The magnetic field distribution in the magnetic core along the line AA' is in the middle part of Fig. 7, and the magnetic field distribution in the magnetic core along the line BB' is shown in the lower part of Fig. 7. In each drawing, a thick solid line represents the magnetic field distribution according to the configuration of the comparative example, and a thin solid line represents the magnetic field distribution according to the configuration of the first embodiment. As also shown in the upper part of Fig. As shown in Figure 7, an alternating current with an amplitude of 70 / 3 [A] and a frequency of 100 kHz was applied to the three electrical conductors in the three-phase AC power line 5, and an alternating current with an amplitude of 70 [A] and a frequency of 100 kHz was applied to the common-mode current circulation line 6. In addition, the relative permeability of each core element was 4000.

[0030] As shown in the analysis result in the middle part of Fig. 7, it can be seen that in the case of the configuration of the first embodiment, a peak value of the magnetic field along the line AA' was lower by about 100 (A / m) than in the configuration of the comparative example. In addition, as shown in the analysis result in the lower part of Fig. 7, it can be seen that in the case of the configuration of the first embodiment, a peak value of the magnetic field along the line BB' was lower by about 130 to 140 (A / m) than in the configuration of the comparative example. Furthermore, as can be seen from the analysis results in the middle part and the lower part of Fig. 7, it can be seen that in most areas along the z-axis direction, the magnetic field strength was lower in the case of the first embodiment than in the comparative example.

[0031] The following describes the reason why the Fig. The analysis results presented in Figure 7 were obtained. Fig. 8 is a diagram to describe the reason why the Fig. The analysis results presented in Figure 7 were obtained.

[0032] When the three-phase AC power line 5 is led out of the power conversion device 50, there is a case where the three-phase AC power line 5 is connected to a terminal block for fixing or insulation purposes, which serves as a connection point of the wiring with the outside, as shown in Fig. 8. Furthermore, when the power conversion device 50 is provided for a railway car, the three-phase AC power line 5 is often formed in a flat ribbon shape, and the respective electric conductors of the three phases are often arranged at intervals on the terminal block. In this case, some of the respective electric conductors of the three phases are bent and led out of the magnetic core 8 when inserted into the terminal block. There is a case where the magnetic flux caused by the bent and led out electric conductor is not canceled, and local magnetic flux is generated around the magnetic core 8. Fig. Figure 8 shows a situation in which local magnetic flux is generated by separating the respective electrical conductors of the three phases from each other, with the electrical conductors being led out of the magnetic core arranged at one outermost end.

[0033] In Fig. 5 and Fig. 6, the three-phase AC power line 5 is formed in a flat ribbon shape and is formed from the core elements 90 and 92, which are analyzed core elements located at the outermost ends, bent and led out. Therefore, local magnetic flux is generated in the core elements 90 and 92. Here, in the core element 90, penetrated by the common-mode current circulation line 6, Fig. 5, a part of the local magnetic flux is canceled by the magnetic flux caused by current flow in the common mode current circulation line 6. In contrast, the local magnetic flux in the core element 92 is Fig. 6, which is not penetrated by the common-mode current circulation line 6, is not canceled and remains therein. Therefore, it is assumed that the magnetic field strength in the core element 90 in the configuration of the first embodiment is lower than in the core element 92 in the configuration of the comparative example.

[0034] Therefore, when the magnetic core 8 of the first embodiment is used, an increase in the magnetic field inside the magnetic core 8 can be prevented, so that the probability of magnetic saturation can be reduced. Furthermore, since the probability of magnetic saturation can be reduced when the magnetic core 8 of the first embodiment is used, it is possible to prevent a decrease in the magnetic permeability of the magnetic core 8 due to magnetic saturation.

[0035] As described above, the railway car power conversion device according to the first embodiment includes a three-phase inverter that converts DC power into AC power for a traction motor installed in a railway car; and a magnetic core penetrated by a three-phase AC power line and a common-mode current circulation line. The three-phase AC power line is an electrical conductor connecting the three-phase inverter and the traction motor. The common-mode current circulation line is an electrical conductor connecting a ground potential of the power conversion device and a ground potential of the traction motor.The magnetic core includes first and second cores penetrated by both the three-phase AC power line and the common-mode current circulation line; and a third core penetrated only by the three-phase AC power line. The first core is disposed on a side closer to the three-phase inverter, the second core is disposed on a side closer to the drive motor, and the third core is disposed between the first core and the second core.

[0036] As described above, the railway car power conversion device according to the first embodiment includes the first and second cores, which are penetrated by both the three-phase AC power line and the common-mode current circulation line; and the third core, which is arranged between the first core and the second core and is penetrated only by the three-phase AC power line among the three-phase AC power line and the common-mode current circulation line. With this configuration, it is possible to prevent the impedance of the circulation path of the common-mode current circulation line from becoming extremely smaller than the impedance of the circulation path of the ground circuit including the ground conductor. 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.

[0037] Furthermore, as described above, the railway car power conversion device according to the first embodiment has a configuration in which the first and second cores, which are penetrated by both the three-phase AC power line and the common-mode current circulation line, are arranged at both ends of the third core, which is penetrated only by the three-phase AC power line. With this configuration, it is possible to prevent an increase in the magnetic field from occurring in each of the core elements located at the outermost ends of the first and second cores. As a result, the probability of magnetic saturation occurring in the magnetic core can be reduced, and a decrease in the magnetic permeability of the magnetic core due to magnetic saturation can be prevented. Second embodiment.

[0038] In a second embodiment, a configuration is described to further reduce the local magnetic flux described in the first embodiment.

[0039] Fig. Fig. 9 is a diagram showing a situation in which the local magnetic flux described in the first embodiment is generated, on a configuration diagram of the magnetic core 8 of Fig. 4.

[0040] Fig. Figure 9 shows a situation in which the electrical conductors 5a and 5c among the three electrical conductors 5a, 5b, and 5c included in the three-phase AC power line 5 are led out of the first core 8a toward the first surface, so that the electrical conductors 5a and 5c are not parallel to the electrical conductor 5b. In addition, Fig. 9 shows a situation in which the electrical conductors 5a and 5c among the three electrical conductors 5a, 5b, and 5c included in the three-phase AC power line 5 are led out of the second core 8b toward the second surface, so that the electrical conductors 5a and 5c are not parallel to the electrical conductor 5b. It should be noted that in Fig. 9 the same constitutional elements as in Fig. 4 are designated by the same reference numerals.

[0041] Furthermore, Fig. 9 shows the magnetic fluxes 100 generated by current flowing through the three-phase AC power line 5 and the magnetic fluxes 110 generated by current flowing through the common-mode current circulation line 6, as well as local magnetic fluxes 120 indicated by dashed lines. The magnetic fluxes 120 may be generated by portions of the electrical conductors 5a and 5c that are not parallel to the electrical conductor 5b. As described above, the magnetic fluxes 100 and the magnetic fluxes 110 oppose each other, so the magnetic fluxes 100 and the magnetic fluxes 110 cancel each other. In contrast, there is no magnetic flux canceling the local magnetic fluxes 120, so components of the local magnetic fluxes 120 remain around the first core 8a and the second core 8b or penetrate into the first core 8a and the second core 8b.

[0042] A configuration of a magnetic core 81 arranged in Fig. 10 is proposed in the second embodiment. Fig. Fig. 10 is a diagram for describing a configuration of the magnetic core 81 included in the power conversion device 50 according to the second embodiment. Fig. 10 are the same constitutional elements as in Fig. 9 are designated by the same reference numerals.

[0043] In the magnetic core 81 of the second embodiment, a non-magnetic metal plate 200 is installed on the first surface of the first core 8a, and the non-magnetic metal plate 200 is also installed on the second surface of the second core 8b, as shown in Fig. 10. An example of the non-magnetic metal plate 200 is an aluminum plate.

[0044] In Fig. 10, since the non-magnetic metal plates 200 are arranged in the yz plane on the first core 8a and the second core 8b, the non-magnetic metal plates 200 interlock with the local magnetic fluxes 120. When the local magnetic fluxes 120 interlock with the non-magnetic metal plates 200, eddy currents flow through the non-magnetic metal plates 200. The eddy currents generate magnetic fluxes in a direction that cancels the local magnetic fluxes 120, thus counteracting the penetration of the local magnetic fluxes 120 into the first core 8a and the second core 8b. As a result, it is possible to prevent the magnetic core 81 from being magnetically saturated by the local magnetic fluxes 120.

[0045] When the power conversion device 50 is provided for a railway car, the size restriction of the power conversion device 50 is greater on the side closer to the drive motor 15 than on the side closer to the three-phase inverter 4, and in many cases, there is insufficient free space on the side closer to the drive motor 15. Therefore, the non-magnetic metal plate 200 is installed on the second surface of the second core 8b in a preferred embodiment. Moreover, when the three-phase AC power line 5 is used in a flat ribbon form, it is difficult to lead out all three electrical conductors 5a, 5b, and 5c included in the three-phase AC power line 5 in parallel to each other and to fix the three electrical conductors 5a, 5b, and 5c to a terminal block.Therefore, it goes without saying that the non-magnetic metal plate 200 is also installed on the first surface of the first core 8a on the side closer to the three-phase inverter 4 in a particularly preferred embodiment.

[0046] It should be noted that although Fig. 10 shows an example in which two electric conductors 5a and 5c among the three electric conductors 5a, 5b, and 5c are not parallel to the other electric conductor 5b. The present embodiment is not limited to this example. Even if one of the three electric conductors 5a, 5b, and 5c is not parallel to the other two electric conductors, that is, for example, the electric conductor 5a is not parallel to the electric conductors 5b and 5c, it is possible to achieve the effect of reducing the local magnetic fluxes 120 by installing the non-magnetic metal plates 200.That is, when at least one of the three electrical conductors 5a, 5b, and 5c included in the three-phase AC power line 5 is led out from the first core 8a toward the first surface or from the second core 8b toward the second surface, the effect of reducing the local magnetic fluxes 120 by the non-magnetic metal plate 200 can be achieved as long as the at least one of the three electrical conductors 5a, 5b, and 5c is not parallel to the remaining one or two electrical conductors. Third embodiment.

[0047] In a third embodiment, a preferred thickness of the non-magnetic metal plate 200 in the magnetic core 81 is described, which is as shown in Fig. 10. Specifically, a non-magnetic metal plate 200 is proposed that has a thickness equal to or greater than a penetration depth in the magnetic core 8 in the power conversion device 50 according to the third embodiment.

[0048] The penetration depth of a metal plate is the distance at which an electromagnetic field penetrating a specific metal material is attenuated to 1 / e (≈1 / 2.718 ≈ -8.7 dB). Where µ is the magnetic permeability of the non-magnetic metal plate 200, σ is the electrical conductivity, and f is the frequency, the penetration depth δ is δ = 1 / √(πfµσ).

[0049] When the thickness of the non-magnetic metal plate 200 in the magnetic core 81 is equal to or greater than the penetration depth of the material of the non-magnetic metal plate 200, the amount of magnetic flux penetrating the first core 8a and the second core 8b can be kept at 1 / e or less compared to the case where the non-magnetic metal plate 200 is not provided. As a result, the magnetic core 81 can be configured so that magnetic saturation is less likely to occur. Fourth embodiment.

[0050] Fig. Fig. 11 is a diagram for describing a configuration of a magnetic core 82 included in the power conversion device 50 according to a fourth embodiment. Fig. The magnetic core 82 shown in Fig. 11 has a fourth core 8d which is arranged between the first core 8a and the third core 8c in the configuration of the magnetic core 81 shown in Fig. 10. The fourth core 8d is penetrated only by the three-phase AC power line 5. In addition, the Fig. 11 has a fifth core 8e added between the second core 8b and the third core 8c. The fifth core 8e is penetrated only by the three-phase AC power line 5. In addition, in the Fig. 11, a non-magnetic metal plate 300 is installed on each of the following surfaces: 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. It should be noted that in the configuration of Fig. 11 no non-magnetic metal plate 200 as used in Fig. 10, is installed on the first surface of the first core 8a and on the second surface of the second core 8b, however, the non-magnetic metal plate 200 may be installed there as shown in Fig. 10. The effect achieved in the case of using the non-magnetic metal plate 200 is the same as in the second embodiment.

[0051] An effect achieved when the non-magnetic metal plate 300 is used will be described below. First, since the common-mode current circulation line 6 is not passed through the fourth core 8d, the third core 8c, or the fifth core 8e, the common-mode current circulation line 6 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 dashed lines, and laid in the magnetic core 82. With this wiring form, local magnetic fluxes are generated at the bent locations, as described in the second embodiment. In the fourth embodiment, the non-magnetic metal plate 300 is installed in such a way as to prevent such local magnetic fluxes from penetrating the first core 8a and the fourth core 8d, as well as 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 being magnetically saturated by local magnetic fluxes that may arise at the bending points of the common-mode current circulation line 6.

[0052] It should be noted that when the thickness of the non-magnetic metal plate 300 is equal to or greater than the penetration depth of the material of the non-magnetic metal plate 200, the same effect as in the third embodiment can be achieved. In addition, in Fig. 11, the non-magnetic metal plate 300 is installed on each of the following surfaces: 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 the present embodiment is not limited to this configuration. When a distance between the first core 8a and the fourth core 8d is greater than the thickness of the non-magnetic metal plate 300, the non-magnetic metal plate 300 can only be installed on a surface closer to the bending point of the common-mode current circulation line 6. For example, when the bending point of the common-mode current circulation 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 can only be installed on the first surface of the fourth core 8d.Accordingly, when the bending position of the common mode current circulation 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 installed only on the second surface of the fifth core 8e. Fifth embodiment.

[0053] Fig. 12 is a diagram for describing a configuration of a magnetic core 83 included in the power conversion device 50 according to a fifth embodiment. Fig. 12 shown magnetic core 83 is the one in Fig. 10 has been divided into two common-mode current circulation lines 6a and 6b. Thus, the common-mode current circulation lines 6a and 6b penetrate the first core 8a and the second core 8b. The common-mode current circulation line 6a, which is one of the two divided lines, is arranged to run parallel to the electrical conductor 5a. Furthermore, the common-mode current circulation line 6b, which is the other of the two divided lines, is arranged to run parallel to the electrical conductor 5c. Note that the term "parallel" used herein refers not only to strict parallelism but also to a substantially parallel arrangement.

[0054] The following describes an effect achieved by the magnetic core 83 of the fifth embodiment. Fig. 12, in-phase zero-phase currents, represented by double-dotted-dashed arrow lines, flow through the electrical conductors 5a, 5b, and 5c. At the same time, in-phase currents, represented by alternating long and short dash arrow lines, flow through the common-mode current circulation lines 6a and 6b. The currents flowing through the common-mode current circulation lines 6a and 6b and the zero-phase currents flowing through the electrical conductors 5a, 5b, and 5c are in opposite phase. Therefore, a magnetic flux generated by the current flowing through the electrical conductor 5a, represented by a solid line, and a magnetic flux generated by the current flowing through the common-mode current circulation line 6a, represented by a dashed line, oppose and cancel each other.Accordingly, a magnetic flux generated by the current flowing through the electric conductor 5c, indicated by a solid line, and a magnetic flux generated by the current flowing through the common-mode current circulation line 6b, indicated by a dashed line, oppose and cancel each other. As a result, even if the electric conductor 5a is bent and led out of the first core 8a and the second core 8b, the common-mode current circulation line 6a arranged in parallel with the electric conductor 5a can prevent the generation of local magnetic flux. Thus, it is possible to prevent magnetic flux from entering the magnetic core 83.Furthermore, even if the electrical conductor 5c is bent and led out of the first core 8a and the second core 8b, the common-mode current circulation line 6b arranged parallel to the electrical conductor 5c makes it possible to prevent the generation of local magnetic flux. Thus, it is possible to prevent magnetic flux from penetrating the magnetic core 83.

[0055] It should be noted that in the configuration of Fig. 12 no non-magnetic metal plate 200 is provided, however, the non-magnetic metal plate 200 can be as in Fig. 10 on the first surface of the first core 8a and the second surface of the second core 8b. In addition, in the fifth embodiment, the following configuration was applied to the configuration of Fig. 10: the common-mode current circulation line 6a, which is one of the two divided lines, is arranged to run parallel to the electrical conductor 5a, which is one of the three electrical conductors 5a, 5b, and 5c as the first electrical conductor, and the common-mode current circulation line 6b, which is the other of the two divided lines, is arranged to run parallel to the electrical conductor 5c, which is one of the three electrical conductors 5a, 5b, and 5c as the second electrical conductor. However, this configuration can also be applied to the configuration according to the fourth embodiment shown in Fig. 11. If this configuration is applied to the configuration of Fig. 11, it is also possible to achieve the effect described in the fourth embodiment.

[0056] The configurations illustrated in the above embodiments show examples, and it is possible to combine the configurations with another known technique or to combine the embodiments with each other, and it is also possible to partially omit or change the configurations without departing from the scope of the present disclosure. List of reference symbols

[0057] 2, 2A input circuit unit; 3 film capacitor; 4 three-phase inverter; 4a switching element; 5 three-phase AC power line; 5a, 5b, 5c electrical conductor; 6, 6a, 6b common mode current circulation line; 7 grounding conductor; 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 pantograph; 12 rail; 13 wheel; 15 traction motor; 21 main transformer; 22 converter; 50 power conversion device; 90, 92 core element; 100, 110 magnetic flux; 120 local magnetic flux; 200, 300 non-magnetic metal plate. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2001-086734

[0006]

Claims

[1] A railway car power conversion device for driving a traction motor installed in a railway car, the railway car power conversion device comprising: a three-phase inverter to convert DC power into AC power for the drive motor; and a magnetic core through which a three-phase AC power line and a common-mode current circulation line are passed, wherein the three-phase AC power line is an electrical conductor connecting the three-phase inverter and the drive motor, wherein the common-mode current circulation line is an electrical conductor connecting a ground potential of the power conversion device and a ground potential of the drive motor, wherein the magnetic core has: a first core disposed on a side closer to the three-phase inverter, the first core being penetrated by both the three-phase AC power line and the common-mode current circulation line; a second core disposed on a side closer to the drive motor, the second core being penetrated by both the three-phase AC power line and the common-mode current circulation line; and a third core disposed between the first core and the second core, the third core being penetrated only by the three-phase AC power line, and wherein, assuming that in each of the first core, the second core, and the third core, a first surface is defined as a surface facing the three-phase inverter and a second surface is defined as a surface facing the drive motor, when at least one of three electrical conductors included in the three-phase AC power line is led out of the second core toward the second surface, the at least one of the three electrical conductors is not parallel to the remaining one or two electrical conductors. [2] A railway car power conversion device according to claim 1, wherein the first core, the second core and the third core are each formed in a rectangular annular shape or a circular annular shape, and a non-magnetic metal plate is installed on the second surface of the second core. [3] The railway car power conversion device according to claim 1 or 2, wherein a non-magnetic metal plate is installed on the first surface of the first core. [4] The railway car power conversion device according to claim 3, wherein when at least one of the three electric conductors included in the three-phase AC power line is led out from the first core toward the first surface, the at least one of the three electric conductors is not parallel to the remaining one or two electric conductors. [5] Railway car power conversion device according to one of claims 2 to 4, comprising: a fourth core disposed between the first core and the third core, the fourth core being penetrated only by the three-phase AC power line; and a fifth core disposed between the second core and the third core, the fifth core being penetrated only by the three-phase AC power line, wherein the fourth core and the fifth core are each formed in a rectangular annular shape or a circular annular shape, and wherein, assuming that in each of the fourth core and the fifth core, a third surface is defined as a surface facing the three-phase inverter and a fourth surface is defined as a surface facing the drive motor, a non-magnetic metal plate is installed 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. [6] The railway car power conversion device according to any one of claims 2 to 5, wherein the non-magnetic metal plate is formed such that the non-magnetic metal plate has a thickness equal to or greater than a penetration depth. [7] A railway car power conversion device according to any one of claims 1 to 6, wherein the common mode current circulation line is divided into two sections penetrating the first core and the second core. [8] A railway car power conversion device according to claim 7, wherein one of the two sections into which the common-mode current circulation line is divided is arranged parallel to a first electrical conductor, the first electrical conductor being one of the three electrical conductors included in the three-phase AC power line, and wherein another of the two sections into which the common-mode current circulation line is divided is arranged in parallel with a second electrical conductor, the second electrical conductor being one of the three electrical conductors included in the three-phase AC power line, the one of the three electrical conductors being different from the first electrical conductor.

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