Power converter

Abstract

The effect of magnetic flux in the busbars of each phase is reduced. [Solution] The power conversion device comprises a first inverter connected to one end of the three-phase winding of an open-winding motor, and a second inverter connected to the other end of the three-phase winding. It comprises a first three-phase conductor connecting one end of each phase of the three-phase winding to each phase of the first inverter, and a second three-phase conductor connecting the other end of each phase of the three-phase winding to each phase of the second inverter, with each phase of the first conductor and each phase of the second conductor arranged so that the conductors of the same phase are parallel and the current flows in opposite directions.

Description

Technical Field

[0001] The present disclosure relates to a power conversion device, and more particularly to a power conversion device including a first inverter connected to one end of a three-phase winding of an open-winding motor and a second inverter connected to the other end of the three-phase winding.

Background Art

[0002] Conventionally, as this type of power conversion device, a device has been proposed in which the U-phase bus bar, V-phase bus bar, W-phase bus bar of the first inverter, and the U-phase bus bar, V-phase bus bar, W-phase bus bar of the second inverter are arranged side by side in this order on a straight line (see, for example, Patent Document 1). The three-phase coils of the first rotating electrical machine are connected to the U-phase, V-phase, and W-phase bus bars of the first inverter, and the three-phase coils of the second rotating electrical machine are connected to the U-phase, V-phase, and W-phase bus bars of the second inverter. Sensors for detecting the current flowing through each bus bar are attached to the U-phase, V-phase, and W-phase bus bars of the first inverter and the second inverter. A converter bus bar is arranged between the W-phase bus bar of the first inverter and the U-phase bus bar of the second inverter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the above-described power conversion device, in order to reduce the interference due to the magnetic flux in each phase bus bar, it is necessary to increase the distance between the bus bars of each phase, resulting in an increase in the size of the device. Further, when using a sensor that detects the magnetic flux generated by the current flowing through the bus bar as a sensor for detecting the current flowing through each bus bar, it is also necessary to correct the sensor value due to the influence of the magnetic flux of other phases.

[0005] The primary objective of the power conversion device of this disclosure is to reduce the influence of magnetic flux in the busbars of each phase. [Means for solving the problem]

[0006] The power conversion device of this disclosure employs the following means to achieve the main objective described above.

[0007] The power conversion device of this disclosure, A power conversion device comprising a first inverter connected to one end of the three-phase winding of an open-winding motor, and a second inverter connected to the other end of the three-phase winding, A three-phase first conductor connecting one end of each phase of the three-phase winding to each phase of the first inverter, A three-phase second conductor connecting the other end of each phase of the three-phase winding to each phase of the second inverter, Equipped with, Each phase of the first conductor and each phase of the second conductor are arranged such that the conductors of the same phase are parallel and the currents flow in opposite directions. It is characterized by the following:

[0008] In the power converter of this disclosure, each phase of the first conductor and each phase of the second conductor are arranged such that the conductors of the same phase are parallel and the current flows in opposite directions. Specifically, the first conductor of the U phase of the first inverter and the second conductor of the U phase of the second inverter are arranged close together and parallel and the current flows in opposite directions, the first conductor of the V phase of the first inverter and the second conductor of the V phase of the second inverter are arranged close together and parallel and the current flows in opposite directions, and the first conductor of the W phase of the first inverter and the second conductor of the W phase of the second inverter are arranged close together and parallel and the current flows in opposite directions. Because the conductors of the same phase are arranged close together and parallel and the current flows in opposite directions, the magnetic flux generated in the first conductor of each phase is canceled out by the magnetic flux generated in the second conductor of the same phase (the magnetic flux generated in the first conductor of the U phase of the first inverter is canceled out by the magnetic flux generated in the second conductor of the U phase of the second inverter (the same applies to the V phase and W phase)). This makes it possible to reduce the influence of magnetic flux in the busbars of each phase.

[0009] In the power converter of this disclosure, the first conductor and the second conductor are formed with a rectangular cross-section, and each phase of the first conductor and each phase of the second conductor may be arranged so that conductors of the same phase face each other or are on the same plane. That is, the longitudinal plane of the cross-section of the first conductor and the longitudinal plane of the cross-section of the second conductor may face each other, or the longitudinal plane of the cross-section of the first conductor and the longitudinal plane of the cross-section of the second conductor may be on the same plane. It is also acceptable to arrange them in this way.

[0010] In the power conversion device of this disclosure, the phases of the first conductor and the phases of the second conductor may be arranged such that the distance between conductors of the same phase is shorter than the distance between conductors of other phases. This further reduces the influence of magnetic flux from other phases.

[0011] In the power conversion device of this disclosure, an insulating wall may be placed between the in-phase conductors of the first conductor and the second conductor. This makes it possible to more reliably avoid unexpected short circuits.

[0012] In the power conversion device of this disclosure, each phase of the first conductor and each phase of the second conductor may be covered with an insulating material. This makes it possible to more reliably avoid unexpected short circuits.

[0013] In the power conversion device of this disclosure, the connection terminals of each phase of the first inverter and the connection terminals of each phase of the second inverter may be configured such that at least one of the positive or negative terminals of the same phase is a common terminal. This reduces the number of terminals.

[0014] The power converter of this disclosure may include a switch for connecting and disconnecting at least one of the positive or negative line connecting the first inverter and the second inverter. This makes it possible to switch between star connection and delta connection of the three-phase windings of an open-winding motor.

[0015] In the power conversion device of this disclosure, a three-phase current sensor may be provided, which is positioned at the same distance from the same-phase conductor between each phase of the first conductor and each phase of the second conductor. That is, the current sensor for the U phase is positioned at a location where the distance from the first conductor of the U phase of the first inverter is the same as the distance from the second conductor of the U phase of the second inverter; the current sensor for the V phase is positioned at a location where the distance from the first conductor of the V phase of the first inverter is the same as the distance from the second conductor of the V phase of the second inverter; and the current sensor for the W phase is positioned at a location where the distance from the first conductor of the W phase of the first inverter is the same as the distance from the second conductor of the W phase of the second inverter. Positioning the current sensors at the same distance from the same-phase conductors with opposite current directions means that the current sensors are positioned at locations where the magnetic flux from each of the same-phase conductors reinforces each other, thus increasing the detection accuracy of the current sensors.

[0016] In a power converter of the present disclosure equipped with such three-phase current sensors, the three-phase current sensors may be arranged between conductors of the same phase. This allows the magnetic fluxes of each conductor of the same phase to further reinforce each other, thereby further increasing the detection accuracy of the current sensors. In this case, each phase of the first conductor and each phase of the second conductor may have recesses formed on the opposing surfaces of the conductors of the same phase, and the three-phase current sensors may be arranged to fit into the recesses of the conductors of the same phase. Furthermore, magnetic cores having open ends near the three-phase current sensors may be arranged around each phase of the first conductor and each phase of the second conductor. This further increases the detection accuracy of the current sensors. [Brief explanation of the drawing]

[0017] [Figure 1] This is a schematic diagram showing the electrical configuration of a drive unit 20 including a power converter 30 as one embodiment of the disclosure. [Figure 2] This is a schematic diagram illustrating the structure of the drive unit 20, including the power converter 30 of the embodiment. [Figure 3] This is a schematic explanatory diagram showing a cross-section near the connection point that connects the power converter 30 of the embodiment to the open-winding motor 70. [Figure 4] This is a schematic explanatory diagram showing a cross-section near the connection point between the positive-side power line 24p and the negative-side power line 24n of the power converter 30 of the embodiment. [Figure 5] This is a schematic diagram illustrating the magnetic flux generated by the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50. [Figure 6] This is a schematic diagram illustrating the first inverter 40 and the second inverter 50 when they are configured using three 4-in-1 modules. [Figure 7]It is an explanatory diagram schematically showing a cross-section near the connection part of the positive power line 24p and the negative power line 24n of the power conversion device 30 when the first inverter 40 and the second inverter 50 are configured by three 4-in-1 modules. [Figure 8] It is an explanatory diagram schematically showing the first inverter 40 and the second inverter 50 when the first inverter 40 and the second inverter 50 are configured by one 12-in-1 module.

[0018] [Figure 9] It is an explanatory diagram schematically showing a cross-section near the connection part of the positive power line 24p and the negative power line 24n of the power conversion device 30 when the first inverter 40 and the second inverter 50 are configured by one 12-in-1 module. [Figure 10] It is an explanatory diagram schematically showing a cross-section near the connection part of the positive power line 24p and the negative power line 24n of the power conversion device 30 when the first inverter 40 and the second inverter 50 are configured by two 12-in-1 modules. [Figure 11] It is an explanatory diagram schematically showing a modified example of the power conversion device 30 in which the bus bars 46U, 46V, 46W of the first inverter 40 and the bus bars 56U, 56V, 56W of the second inverter 50 are covered by the insulation coating parts 47U, 47V, 47W. [Figure 12] It is an explanatory diagram schematically showing a modified example of the power conversion device 30 in which partition walls 66U, 66V, 66W are attached between the bus bars of the same phase of the bus bars 46U, 46V, 46W of the first inverter 40 and the bus bars 56U, 56V, 56W of the second inverter 50. [Figure 13] It is an explanatory diagram schematically showing a modified example of the power conversion device 30 in which the negative connection terminals of the same phase use the common negative common connection terminals 4454U, 4454V, 4454V. [Figure 14] It is an explanatory diagram schematically showing a cross-section near the connection part of the positive power line 24p and the negative power line 24n of the power conversion device 30 in a modified example in which the negative connection terminals of the same phase use the common negative common connection terminals 4454U, 4454V, 4454V. [Figure 15] This is a schematic explanatory diagram showing a modified power converter 30 that uses common positive terminals 4252U, 4252V, and 4252V for the positive terminal connection terminals of the same phase. [Figure 16] This is a schematic explanatory diagram showing a cross-section near the connection point between the positive side power line 24p and the negative side power line 24n of a modified power converter 30 using common positive side connection terminals 4252U, 4252V, and 4252V, which are in phase.

[0019] [Figure 17] This is a schematic explanatory diagram showing a modified power converter 30 in which the positive terminals of the same phase are common positive terminals 4252U, 4252V, 4252V, and the negative terminals of the same phase are common negative terminals 4454U, 4454V, 4454V. [Figure 18] This is a schematic explanatory diagram showing a cross-section near the connection point between the positive side power line 24p and the negative side power line 24n of a modified power converter 30, in which the positive side connection terminals of the same phase are common positive side connection terminals 4252U, 4252V, and 4252V, and the negative side connection terminals of the same phase are common negative side connection terminals 4454U, 4454V, and 4454V. [Figure 19] This is a schematic explanatory diagram showing a modified power converter 30 in which the busbars of the same phase are arranged so that their longitudinal surfaces in the cross-section face each other, and the busbars of other phases are arranged so that their longitudinal surfaces in the cross-section face each other. [Figure 20] This is a schematic explanatory diagram showing a modified power conversion device 30 in which the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50 are arranged so that their longitudinal surfaces in the cross-section are on the same plane. [Figure 21] This is a schematic explanatory diagram showing a modified power converter 30 in which current sensors 64U, 64V, and 64W are placed between in-phase busbars at positions offset from the center, but at the same distance from the in-phase busbars. [Figure 22]This is a schematic explanatory diagram showing a modified power converter 30 in which current sensors 64U, 64V, and 64W are placed between in-phase busbars at positions offset from the center, but at the same distance from the in-phase busbars. [Figure 23] This is a schematic explanatory diagram showing a modified power converter 30 in which current sensors 64U, 64V, and 64W are placed between in-phase busbars at positions offset from the center, but at the same distance from the in-phase busbars. [Figure 24] This is a schematic explanatory diagram showing a modified power converter 30, in which recesses are formed on the opposing faces of the same-phase busbars 46U, 46V, 46W of the first inverter 40 and 56U, 56V, 56W of the second inverter 50, and current sensors 64U, 64V, 64W are placed in the center of the recesses. [Figure 25] This is a schematic explanatory diagram showing a modified power converter 30 in which the in-phase busbars of the first inverter 40 (busbars 46U, 46V, 46W) and the second inverter 50 (busbars 56U, 56V, 56W) are surrounded by magnetic cores 68U, 68V, 68W. [Modes for carrying out the invention]

[0020] Next, embodiments for carrying out the present disclosure will be described. Figure 1 is a schematic diagram showing the electrical configuration of a drive unit 20 including a power converter 30 as one embodiment of the present disclosure, and Figure 2 is a schematic structural diagram showing the structure of the drive unit 20 including the power converter 30 of the embodiment. Figure 3 is an explanatory diagram showing a schematic cross-section near the connection part connecting the power converter 30 of the embodiment to the open-winding motor 70, and Figure 4 is an explanatory diagram showing a schematic cross-section near the connection part between the positive-side power line 24p and the negative-side power line 24n of the power converter 30 of the embodiment. The drive unit 20 of the embodiment comprises a battery 22, a power converter 30, and an open-winding motor 70.

[0021] The battery 22 is configured as, for example, a lithium-ion secondary battery or a nickel-metal hydride secondary battery, and its positive and negative terminals are connected to the positive power line 24p and the negative power line 24n. A smoothing capacitor 26 is attached to the positive power line 24p and the negative power line 24n.

[0022] The power converter 30 comprises a first inverter 40, a second inverter 50, and connection switches 60p and 60n.

[0023] The first inverter 40 is connected to the positive power line 24p and the negative power line 24n to which the battery 22 is connected, and has six switching elements, transistors T11 to T16, and six diodes D11 to D16 connected in parallel to each of the six transistors T11 to T16. The transistors T11 to T16 are made up of, for example, SiC-MOSFETs (SiC - Metal Oxide Semiconductor Field Effect Transistors). Two transistors from transistors T11 to T16 are paired together (transistor T11 and transistor T14, transistor T12 and transistor T15, and transistor T13 and transistor T16). These pairs are arranged to act as the source and sink sides with respect to the positive power line 24p and the negative power line 24n. As shown in Figures 1 and 4, they are connected to the positive power line 24p by positive terminals 42U, 42V, and 42W, and to the negative power line 24n by negative terminals 44U, 44V, and 44W. In addition, each of the connection points of the pairs of transistors T11 to T16 is connected to one end of the three-phase coil 72U, 72V, and 72W of the open-wound motor 70 by busbars 46U, 46V, and 46W made of conductive metal, as shown in Figures 1 and 2. The first inverter 40 is composed of three modules, each consisting of two pairs of transistors for each phase and two diodes connected in parallel, forming a 2-in-1 module for each phase.

[0024] The second inverter 50 is connected to the first inverter 40 by the battery 22, with the battery 22 connecting to the positive power line 24p and the negative power line 24n. The second inverter 50 has six switching elements, transistors T21 to T26, and six diodes D21 to D26 connected in parallel to each of the six transistors T21 to T26. Transistors T11 to T16 are composed of SiC-MOSFETs, similar to the transistors T11 to T16 of the first inverter 40. The transistors T21 to T26 are arranged in pairs (transistor T21 and T24, transistor T22 and T25, and transistor T23 and T26) so that they are the source and sink sides with respect to the positive power line 24p and the negative power line 24n. As shown in Figures 1 and 4, they are connected to the positive power line 24p by positive terminals 52U, 52V, and 52W, and to the negative power line 24n by negative terminals 54U, 54V, and 54W. In addition, each of the connection points of the pairs of transistors T21 to T26 is connected to the other end of the three-phase coil 72U, 72V, and 72W of the open-wound motor 70 by busbars 56U, 56V, and 56W made of conductive metal, as shown in Figures 1 and 2. Furthermore, similar to the first inverter 40, the second inverter 50 is composed of three modules, each consisting of two pairs of transistors for each phase and two diodes connected in parallel, forming a 2-in-1 module for each phase.

[0025] A connecting switch 60p is installed between the first inverter 40 and the second inverter 50 on the positive side power line 24p, and a connecting switch 60n is installed between the first inverter 40 and the second inverter 50 on the negative side power line 24n. The connecting switches 60p and 60n are composed of SiC-MOSFETs, similar to the transistors T11 to T16 of the first inverter 40 and the transistors T21 to T26 of the second inverter 50.

[0026] The open-wound motor 70 is a generator-motor configured with three-phase coils 72U, 72V, and 72W for the u, v, and w phases, with both ends serving as connection terminals. One end of the three-phase coils 72U, 72V, and 72W is connected to three connection points of a pair of transistors of the first inverter 40 by busbars 46U, 46V, and 46W, while the other end of the three-phase coils 72U, 72V, and 72W is connected to three connection points of a pair of transistors of the second inverter 50 by busbars 56U, 56V, and 56W.

[0027] In the power conversion device 30 of this embodiment, the open-wound motor 70 can be driven in a star configuration by switching control of transistors T11 to T16 of the first inverter 40 while the connecting switches 60p and 60n are turned off, and the transistors T21 to T23 on the upper arm of the second inverter 50 are turned on and the transistors T24 to T26 on the lower arm are turned off. That is, by turning off the connecting switches 60p and 60n and turning on the transistors T21 to T23 on the upper arm of the second inverter 50, the u-phase, v-phase, and w-phase of the open-wound motor 70 are turned on, and the transistors T21 to T23 form a neutral point, and the open-wound motor 70 is driven by the first inverter 40 as a star-connected motor. On the other hand, by switching the transistors T11 to T16 of the first inverter 40 and the transistors T21 to T26 of the second inverter 50 with the connection switches 60p and 60n turned ON, the open-wound motor 70 can be driven in a delta connection.

[0028] As shown in Figure 3, the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50, which are connected to the three-phase coils 72U, 72V, and 72W of the open-winding motor 70, have a rectangular cross-section. The busbars of the same phase (busbar 46U and busbar 56U, busbar 46V and busbar 56V, busbar 46W and busbar 56W) are arranged so that their longitudinal surfaces in the cross-section face each other and are parallel, and so that the current flows in opposite directions. Busbars 46U, 46V, 46W and 56U, 56V, 56W are arranged such that the distance between busbars of the same phase (distance between busbars 46U, 56U; distance between busbars 46V, 56V; distance between busbars 46W, 56W) is shorter than the distance between busbars of other phases (distance between U-phase busbars and V-phase busbars; distance between V-phase busbars and W-phase busbars; distance between W-phase busbars and U-phase busbars). In other words, the distance between busbars of other phases is longer than the distance between busbars of the same phase. This is to minimize the influence of magnetic flux generated by the current flowing through busbars of other phases. In addition, current sensors 64U, 64V, 64W, which detect current by the strength of magnetic flux, are placed between busbars of the same phase at the same distance from the busbars.

[0029] Figure 5 is a schematic diagram illustrating the magnetic flux generated by the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50. In the figure, circles with a black circle in the center indicate that the current flowing through the busbar is flowing from the back to the front, and circles with an "X" inside indicate that the current flowing through the busbar is flowing from the front to the back. Since the current flows in opposite directions through busbars of the same phase (busbars 46U and 56U, 46V and 56V, and 46W and 56W), the magnetic flux generated by one of the busbars of the same phase cancels out the magnetic flux generated by the other, so the magnetic flux generated by the busbars of the same phase is small overall. For this reason, the influence of the magnetic flux generated by the busbars of the same phase on other phases is small. On the other hand, since the magnetic flux generated by each busbar reinforces each other between busbars of the same phase, the current sensors 64U, 64V, and 64W, which are positioned in the center of the busbars of the same phase, can accurately detect the current flowing through the busbars of the same phase. Furthermore, as mentioned above, the influence of the magnetic flux generated by busbars of the same phase on other phases is small, so the influence of the magnetic flux generated by other phases on the current sensors 64U, 64V, and 64W is also small, resulting in higher detection accuracy.

[0030] In the power converter 30 of the embodiment described above, the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50 are arranged such that the longitudinal surfaces of the cross-sections of the busbars of the same phase face each other and are arranged parallel to one another, and the current flows in opposite directions. Therefore, the magnetic flux generated by the current flowing through each busbar of the same phase cancels out on the outer circumference of each busbar of the same phase, thus reducing the influence of the magnetic flux generated by the current flowing through each busbar of the same phase on other phases. Furthermore, since the distance to the busbars of other phases is longer than the distance to the busbars of the same phase, the influence of the magnetic flux generated by the current flowing through each busbar of the same phase on other phases can be further reduced. In addition, the clearance between busbars of the same phase can be reduced. As a result of these measures, the power converter 30 can be miniaturized.

[0031] Furthermore, in the power converter 30 of this embodiment, the busbars of the same phase are arranged so that their longitudinal surfaces in the cross-section face each other and are parallel to one another, and so that the current flows in opposite directions. Current sensors 64U, 64V, and 64W are also placed at the same distance from the busbars between the busbars of the same phase. Since the magnetic flux generated by the current flowing through each busbar of the same phase reinforces each other between the busbars of the same phase, the current sensors 64U, 64V, and 64W placed between the busbars of the same phase can accurately detect the current flowing through the busbars of the same phase. Moreover, the influence of the magnetic flux generated by the busbars of the same phase on other phases is small, so the influence of the magnetic flux generated by other phases on the current sensors 64U, 64V, and 64W can be reduced, and the detection accuracy can be further improved.

[0032] In the power converter 30 of this embodiment, the first inverter 40 and the second inverter 50 are configured with six 2-in-1 modules, where each phase consists of two pairs of transistors and two diodes connected in parallel, forming a module (2-in-1 module) for each phase. However, as shown in Figures 6 and 7, the two pairs of transistors and two diodes connected in parallel for each phase of the first inverter 40 and the two pairs of transistors and two diodes connected in parallel for the same phase of the second inverter 50 may be combined into one module (4-in-1 module), and the first inverter 40 and the second inverter 50 may be configured with three 4-in-1 modules. Alternatively, as shown in Figures 8 and 9, all the transistors and diodes connected in parallel for the first inverter 40 and all the transistors and diodes connected in parallel for the second inverter 50 may be combined into one module (12-in-1 module), and the first inverter 40 and the second inverter 50 may be configured with one 12-in-1 module. Furthermore, as shown in Figure 10, all the transistors of the first inverter 40 and the diodes connected in parallel with them may be made into a single module (6-in-1 module), and all the transistors of the second inverter 50 and the diodes connected in parallel with them may also be made into a single module (6-in-1 module), so that the first inverter 40 and the second inverter 50 are composed of two 6-in-1 modules.

[0033] In the power converter 30 of this embodiment, the busbars 46U, 46V, 46W of the first inverter 40 and the busbars 56U, 56V, 56W of the second inverter 50 are left with their conductors exposed directly from the module. However, as shown in the modified example in Figure 11, the busbars 46U, 46V, 46W of the first inverter 40 and the busbars 56U, 56V, 56W of the second inverter 50 may be covered with insulating coatings 47U, 47V, 47W, 57U, 57V, 57W formed of insulating material, except for the connection ends with the three-phase coils 72U, 72V, 72W of the open-winding motor 70. In this case, short circuits between terminals due to foreign matter contamination can be prevented more reliably. Furthermore, as shown in the modified example in Figure 12, partition walls 66U, 66V, and 66W, made of insulating material, may be installed between the in-phase busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50. In this case as well, short circuits between terminals due to foreign matter contamination can be prevented more reliably.

[0034] In the power converter 30 of this embodiment, a connecting switch 60p is installed between the first inverter 40 and the second inverter 50 on the positive side power line 24p, and a connecting switch 60n is installed between the first inverter 40 and the second inverter 50 on the negative side power line 24n. However, it is also acceptable to omit one or both of the connecting switches 60p and 60n. If the connecting switch 60n is not installed between the first inverter 40 and the second inverter 50 on the negative side power line 24n, as shown in Figures 13 and 14, the negative side connection terminals 44U, 44V, 44W of the first inverter 40 and the negative side connection terminals 54U, 54V, 54W of the second inverter 50 may be replaced with common negative side connection terminals 4454U, 4454V, 4454V for the same phase. Furthermore, if a connecting switch 60p is not installed between the first inverter 40 and the second inverter 50 on the positive side power line 24p, the positive side connection terminals 42U, 42V, 42W of the first inverter 40 and the positive side connection terminals 52U, 52V, 52W of the second inverter 50 may be set to common positive side connection terminals 4252U, 4252V, 4252V, as shown in Figures 15 and 16. Furthermore, if connecting switches 60p and 60n are not installed between the first inverter 40 and the second inverter 50 on the positive side power line 24p and the negative side power line 24n, as shown in Figures 17 and 18, the positive side connection terminals 42U, 42V, 42W of the first inverter 40 and the positive side connection terminals 52U, 52V, 52W of the second inverter 50 may be made into common positive side connection terminals 4252U, 4252V, 4252V, and the negative side connection terminals 44U, 44V, 44W of the first inverter 40 and the negative side connection terminals 54U, 54V, 54W of the second inverter 50 may be made into common negative side connection terminals 4454U, 4454V, 4454V.

[0035] In the power converter 30 of this embodiment, as shown in Figure 5, the busbars 46U, 46V, and 46W of the first inverter 40 are arranged so that their longitudinal surfaces in the cross-section are on the same plane, and the busbars 56U, 56V, and 56W of the second inverter 50 are also arranged so that their longitudinal surfaces in the cross-section are on the same plane, and the busbars of the same phase are arranged so that their longitudinal surfaces in the cross-section face each other. However, as shown in the modified example in Figure 19, the busbars of the same phase may be arranged so that their longitudinal surfaces in the cross-section face each other, and the busbars of other phases may be arranged so that their longitudinal surfaces in the cross-section face each other. Furthermore, as shown in Figure 20, the busbars 46U, 46V, and 46W of the first inverter 40 may be arranged so that their longitudinal surfaces in the cross-section are on the same plane, and the busbars 56U, 56V, and 56W of the second inverter 50 may also be arranged so that their longitudinal surfaces in the cross-section are on the same plane. In addition, all of the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50 may be arranged so that their longitudinal surfaces in the cross-section are on the same plane.

[0036] In the power converter 30 of this embodiment, current sensors 64U, 64V, and 64W are positioned in the center of the in-phase busbars between the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50. However, the position of the current sensors 64U, 64V, and 64W only needs to be the same distance from the in-phase busbars between them. Therefore, as shown in Figures 21 to 23, the current sensors 64U, 64V, and 64W may be positioned at locations offset from the center between the in-phase busbars, where the distance from the in-phase busbars is the same.

[0037] In the power converter 30 of this embodiment, current sensors 64U, 64V, and 64W are positioned in the center of the in-phase busbars between the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50. However, as shown in the modified example in Figure 24, recesses may be formed on the opposing faces of the in-phase busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50, and current sensors 64U, 64V, and 64W may be positioned so that they are fitted into the center of the recesses of the in-phase busbars. In this way, the strength of the magnetic flux reinforced by the current flowing through each in-phase busbar increases, so that the detection accuracy of the current sensors 64U, 64V, and 64W can be increased.

[0038] In the power converter 30 of this embodiment, current sensors 64U, 64V, and 64W are positioned in the center of the in-phase busbars between the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50. However, the area around the in-phase busbars of the busbars 46U, 46V, and 46W of the first inverter 40 and the busbars 56U, 56V, and 56W of the second inverter 50 may be covered with magnetic cores 68U, 68V, and 68W. In this case, it is preferable that the magnetic cores 68U, 68V, and 68W are formed to have open ends near the current sensors 64U, 64V, and 64W. This increases the strength of the magnetic flux reinforced by the current flowing through each in-phase busbar, thereby improving the detection accuracy of the current sensors 64U, 64V, and 64W.

[0039] The correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem will be explained. In the embodiment, the open-wound motor 70 corresponds to the "open-wound motor", the three-phase coils 72U, 72V, and 72W correspond to the "three-phase winding", the first inverter 40 corresponds to the "first inverter", the second inverter 50 corresponds to the "second inverter", the busbars 46U, 46V, and 46W of the first inverter 40 correspond to the "first conductor of the three phase", and the busbars 56U, 56V, and 56W of the second inverter 50 correspond to the "second conductor of the three phase".

[0040] Furthermore, the correspondence between the main elements of the embodiment and the main elements of the invention described in the section on means for solving the problem is merely an example to specifically explain the form in which the embodiment implements the invention described in the section on means for solving the problem, and does not limit the elements of the invention described in the section on means for solving the problem. In other words, the interpretation of the invention described in the section on means for solving the problem should be based on the description in that section, and the embodiment is merely one specific example of the invention described in the section on means for solving the problem.

[0041] Although the present disclosure has been described above using embodiments, the present disclosure is not limited in any way to these embodiments, and can of course be implemented in various forms without departing from the gist of the present disclosure. [Industrial applicability]

[0042] This disclosure can be used in industries such as the manufacturing of power conversion equipment. [Explanation of Symbols]

[0043] 20 Drive unit, 22 Battery, 24p Positive power line, 24n Negative power line, 26 Capacitor, 30 Power converter, 40 First inverter, 42U, 42V, 42W Positive connection terminal, 44U, 44V, 44W Negative connection terminal, 46U, 46V, 46W Busbar, 47U, 47V, 47W Insulation coating, 50 Second inverter, 52U, 52V, 52V Positive connection terminal, 54U, 54V, 54W Negative connection terminal, 56U, 56V, 56W Busbar, 57U, 57V, 57W Insulation coating, 60p, 60n Connection switch, 66U, 66V, 66W Partition, 68U, 68V, 68W Magnetic core, 70 Open-wound motor, 72U, 72V, 72W three-phase coil, 4252U, 4252V, 4252W common connection terminal on the positive side, 4454U, 4454V, 4454W common connection terminal on the negative side, T11~T16, T21~T26 transistor, D11~D16, D21~D26 diode.

Claims

1. A power conversion device comprising a first inverter connected to one end of the three-phase winding of an open-winding motor, and a second inverter connected to the other end of the three-phase winding, A three-phase first conductor connecting one end of each phase of the three-phase winding to each phase of the first inverter, A three-phase second conductor connecting the other end of each phase of the three-phase winding to each phase of the second inverter, Equipped with, Each phase of the first conductor and each phase of the second conductor are arranged such that the conductors of the same phase are parallel and the current flows in opposite directions. A power conversion device characterized by the following features.

2. A power conversion device according to claim 1, The first conductor and the second conductor are formed with a rectangular cross-section. Each phase of the first conductor and each phase of the second conductor are arranged such that conductors of the same phase face each other or lie on the same plane. Power converter.

3. A power conversion device according to claim 1, Each phase of the first conductor and each phase of the second conductor are arranged such that the distance between conductors of the same phase is shorter than the distance between conductors of other phases. Power converter.

4. A power conversion device according to claim 1, An insulating wall is placed between the first conductor and the second conductor, which are in the same phase. Power converter.

5. A power conversion device according to claim 1, Each phase of the first conductor and each phase of the second conductor are covered with an insulating material. Power converter.

6. A power conversion device according to claim 1, The connection terminals of each phase of the first inverter and the connection terminals of each phase of the second inverter are configured such that at least one of the positive or negative terminals of the same phase is a common terminal. Power converter.

7. A power conversion device according to claim 1, The system includes a switch for connecting to and disconnecting at least one of the positive or negative terminal lines connecting the first inverter and the second inverter. Power converter.

8. A power conversion device according to any one of claims 1 to 7, The system includes a three-phase current sensor where each phase of the first conductor and each phase of the second conductor are positioned at the same distance from the same-phase conductor. Power converter.

9. A power conversion device according to claim 8, The three-phase current sensor is positioned between conductors of the same phase. Power converter.

10. A power conversion device according to claim 9, Each phase of the first conductor and each phase of the second conductor have recesses formed on the opposing surfaces of the conductors of the same phase. The three-phase current sensor is positioned to fit into the recess of the conductor of the same phase. Power converter.

11. A power conversion device according to claim 9, A magnetic core having an open end near the three-phase current sensor is arranged around each phase of the first conductor and each phase of the second conductor. Power converter.

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