Motor drive device

Abstract

Provided is a motor drive device capable of achieving a desired circuit configuration despite having a small number of types of bus bars. The motor drive device has a bus bar assembly including a first bus bar and a second bus bar, and a coupling means for coupling the first bus bar and the second bus bar to each other. The first bus bar, the second bus bar, and the coupling means are configured such that the bus bar assembly has a plurality of shapes that differ in position and / or posture of the second bus bar with respect to the first bus bar.

Description

Motor drive unit

[0001] The present disclosure relates to a motor drive device.

[0002] A motor drive device is known as a drive device that drives a motor used in applications such as driving each axis of a machine tool or a robot. A typical motor drive device includes electronic components such as power elements and capacitors for supplying current to the motor. Because a relatively large current flows through these electronic components, a bus bar made of metal such as copper, brass, or aluminum is sometimes used as an electrical connection means for these electronic components.

[0003] Busbars are required to have various sizes and shapes depending on the size and shape of the circuit (printed circuit board) in the motor drive device to which they are mounted, and many busbars are manufactured by casting using a mold or the like.

[0004] JP 2021-100320 A Republished 2017 / 187606 A

[0005] Busbars of various sizes and shapes are required depending on the circuits of the motor drive device, which increases the number of parts in the motor drive device and leads to higher costs.In addition, when busbars of different sizes and shapes are used, it is difficult to standardize the molds used to manufacture busbars, so it becomes necessary to prepare different molds for each busbar, which also increases the cost of the motor drive device.

[0006] Therefore, there is a demand for a motor drive device that can realize a desired circuit configuration despite having a limited number of types of bus bars.

[0007] One aspect of the present disclosure is a motor drive device having a busbar assembly including a first busbar, a second busbar, and a coupling means for coupling the first busbar and the second busbar to each other, wherein the first busbar, the second busbar, and the coupling means are configured such that the busbar assembly has a plurality of shapes in which at least one of the position or attitude of the second busbar relative to the first busbar is different.

[0008] FIG. 1 is a schematic perspective view of a motor drive device according to an embodiment. FIG. 2 is a diagram schematically illustrating a main circuit of the motor drive device of FIG. 1. FIG. 3 is a schematic configuration diagram of a bus bar according to a first embodiment. FIG. 4 is a schematic configuration diagram of a bus bar according to a second embodiment. FIG. 5 is a schematic configuration diagram of a bus bar according to a third embodiment. FIG. 6 is a schematic configuration diagram of a bus bar according to a fourth embodiment. FIG. 7 is a schematic configuration diagram of a bus bar according to a fifth embodiment. FIG. 8 is a schematic configuration diagram of a bus bar according to a sixth embodiment. FIG. 9 is a schematic configuration diagram of a bus bar according to a ninth embodiment. FIG. 10 is a schematic configuration diagram of a bus bar according to a tenth embodiment.

[0009] 1 is a perspective view showing the schematic configuration of a motor drive device 10 according to a preferred embodiment. The motor drive device 10 is a device for driving a motor 2 shown in the schematic diagram, and includes a housing 12 and a printed circuit board (not shown) provided inside the housing 12 and on which electronic components such as drive circuit components are mounted. The motor drive device 10 optionally includes a flange 14, a cooling fan 16, and at least one connector 18 to which cables (not shown) for supplying power and communicating signals can be detachably attached to the motor drive device 10. The motor 2 is, for example, a servo motor or the like that drives each axis of a machine tool or robot, and the drive circuit components are, for example, power elements.

[0010] 2 schematically illustrates a portion of the main circuit of the motor drive device 10. The motor drive device 10 includes an input terminal 20 connected to a power source 4 (shown schematically) via a cable or the like, and an output terminal 22 connected to a motor 2 (shown schematically) via a cable or the like. The motor drive device 10 also includes a diode (power element) 24, a capacitor 26, an inverter 28, and the like mounted on the printed circuit board. In this embodiment, a bus bar assembly (described later) is provided as a conductive connection means between the input terminal 20 and the diode 24 (input section 30), between the diode 24, the capacitor 26, and the inverter 28 (DC link section 32), and / or between the inverter 28 and the output terminal 22 (output section 34) to electrically connect the various elements. Various examples of bus bars are described below.

[0011] 3 shows a schematic configuration of a bus bar assembly 40a according to a first embodiment. The bus bar assembly 40a includes multiple bus bars 42 (two, first and second, in the illustrated example) made of a conductive metal material such as copper, brass, or aluminum. Each bus bar 42 is generally L-shaped and includes a long side portion 44, a short side portion 46 extending substantially perpendicularly from one end of the long side portion 44, and a connection portion 48 formed at the end of the short side portion 46 opposite the long side portion 44. The connection portion 48 is electrically connected to a printed circuit board (not shown) or the like by a fastening means such as a screw (not shown). The two bus bars 42 are identical in size and shape, and therefore can be manufactured from a single mold by casting or the like.

[0012] Each bus bar 42 has a first and second through-holes 50 formed at the other end opposite the short side, through which a fastening means such as a bolt 52 can be inserted. The through-holes 50 of the two bus bars 42 are aligned, and then a bolt 52 or other insertion member is inserted into the hole 50. The two bus bars 42 are joined together using a fastening member such as a nut 54 that is threaded onto the bolt 52, thereby forming a bus bar assembly 40a. The angle θ formed by the long sides 44 of the two bus bars 42 can be set arbitrarily, allowing assemblies 40a of various shapes to be formed using multiple bus bars of the same shape. Therefore, the use of the assembly 40a greatly increases the degree of freedom in circuit design in a motor drive device.

[0013] Note that the fact that each bus bar is made of a conductive metal material such as copper, brass, or aluminum, and the structure of the short side portion 46 and the connection portion 48 may be common to the second to tenth embodiments described later, and therefore, description of these aspects will be omitted in the second to tenth embodiments.

[0014] 4 shows a schematic configuration of a bus bar assembly 40b according to Example 2. The bus bar assembly 40b has a configuration in which the first bus bar 42 in Example 1 is combined with a second bus bar 56, which will be described later.

[0015] The bus bar 56 has a substantially L-shaped configuration similar to that of the bus bar 42, but differs from the bus bar 42 in that a long side 58 thereof has an elongated hole 60 extending along the longitudinal direction of the long side 58. The elongated hole 60 is sized to allow insertion of an insertion member such as a bolt 52. Therefore, the through hole 50 of the bus bar 42 is aligned with the elongated hole 60, the bolt 52 is inserted into the through hole 50 and the elongated hole 60, and the two bus bars are joined together using a fastening member such as a nut 54 threaded onto the bolt 52, thereby forming a bus bar assembly 40b. Note that the elongated hole 60 in the bus bar 56 not only allows the angle between the long sides of the two bus bars to be changed as in the first embodiment, but also allows the length of the assembly 40b along the arrow 62 to be set as desired depending on the length of the elongated hole 60. Therefore, the use of the assembly 40b further increases the degree of freedom in circuit design in the motor drive device.

[0016] 5 shows a schematic configuration of a bus bar assembly 40c according to Example 3. The bus bar assembly 40c has a configuration in which a first bus bar 64 and a second bus bar 65 are coupled to each other.

[0017] Bus bar 64 has a substantially L-shape that is roughly the same as bus bar 42, but has at least three (eight in the illustrated example) first through holes 68 formed at the tip of its long side 66 and arranged on concentric circles. Bus bar 65 differs from bus bar 64 only in that eight holes (not shown) are screw holes (tapped holes).

[0018] The bus bar assembly 40c can be constructed by aligning the first through holes 68 of the bus bar 64 with the tapped holes (not shown) of the bus bar 65 and connecting the two bus bars to each other using connecting means such as screws 70. In the illustrated example, the number of screws 70 is the same as the number of through holes 68, but this is not limited thereto. For example, four screws 70 may be used, with every other screw 70 positioned between them. The number of screws 70 may be sufficient to firmly fasten the bus bars 64 and 65 to each other. Furthermore, instead of the screws 70, a bolt and nut combination as described in the second embodiment may be used, in which case the tapped holes of the bus bar 65 can be replaced with second through holes.

[0019] 5, the through holes 68 are arranged concentrically, and therefore the angle of the bus bar 64 relative to the bus bar 65 can be changed depending on the number of through holes 68. For example, in FIG. 5, the angle between the long sides of the two bus bars is approximately 90°, but if there are eight through holes 68, this angle can be changed arbitrarily in increments of 45°.

[0020] 6 shows a schematic configuration of a bus bar assembly 40d according to Example 4. The first bus bar 72 and the second bus bar 73 constituting the bus bar assembly 40d have a substantially L-shape that is roughly the same as the bus bars 64 and 65 of Example 3, but differs in that the angle formed by the two bus bars in Example 3 is variable, whereas the length of the assembly 40d in Example 4 is variable.

[0021] Specifically, bus bar 72 has three or more third through holes 76 on the tip side of its long side portion 74, and in the illustrated example, has two rows of five through holes (10 in total) arranged at equal intervals along the longitudinal direction of long side portion 74. On the other hand, bus bar 73 has three or more fourth tapped holes or through holes 77 on the tip side of its long side portion 75, and in the illustrated example, has two rows of five tapped holes or through holes (10 in total) arranged at the same equal intervals as the through holes 76 along the longitudinal direction of long side portion 75.

[0022] Busbar assembly 40d can be constructed by joining two busbars together using joining means such as a plurality of screws 70 while at least two through holes 76 in busbar 72 are aligned with tapped holes 77 in busbar 73. In the fourth embodiment, assembly 40d can be constructed whose length is variable in the direction of arrow 78 depending on the number of through holes 76 and tapped holes 77 that are aligned with each other. In addition, although the angle between the long sides of the two busbars in Figure 6 is approximately 180°, this angle can also be 90° by locating the through holes at positions corresponding to the vertices of a square.

[0023] In the example of Fig. 6, bus bar 72 has through holes 76 and bus bar 73 has tapped holes 77, but some of the through holes 76 of bus bar 72 may be changed to tapped holes, and some of the tapped holes of bus bar 73 may be changed to through holes. In that case, the insertion direction of screws 70 is reversed from that in Fig. 6. In this way, each of bus bars 72 and 73 can have both through holes and tapped holes.

[0024] 7 shows a schematic configuration of a bus bar assembly 40e according to a fifth embodiment. This embodiment roughly corresponds to a combination of the third and fourth embodiments, and the first bus bar 72a and the second bus bar 73a constituting the bus bar assembly 40e have a substantially L-shape roughly equivalent to the bus bars 72 and 73 of the fourth embodiment.

[0025] Specifically, bus bar 73a has at least three (eight in the illustrated example) through holes 68 formed at the tip of its long side portion 75a and arranged on a concentric circle. Bus bar 72a also has at least three (eight in the illustrated example) tapped holes (not shown) formed at the tip of its long side portion 74a and arranged on a concentric circle having the same diameter as the concentric circle formed by through holes 68.

[0026] Furthermore, busbar 72a has three or more through holes 76 or tapped holes 77 on the tip side of its long side portion 74a, and in the illustrated example, has two rows (eight in total) of two through holes 76 and two tapped holes 77 arranged at equal intervals along the longitudinal direction of long side portion 74a. On the other hand, busbar 73a has three or more tapped holes 77 or through holes 76 on the tip side of its long side portion 75a, and in the illustrated example, has two rows (eight in total) of two tapped holes 77 and two through holes 76 arranged at the same equal intervals as the through holes 76 and tapped holes 77 of busbar 72a along the longitudinal direction of long side portion 75a.

[0027] The fifth embodiment has the functions of both the third and fourth embodiments. That is, by connecting bus bars 72a and 73a using concentrically arranged through holes 68 and corresponding tapped holes, the angle of bus bar 73a relative to bus bar 72a can be changed depending on the number of through holes 68. Furthermore, by connecting two bus bars to each other using connecting means such as a plurality of screws 70 while aligning the through holes 76 or tapped holes 77 of bus bar 72a with the tapped holes 77 or through holes 76 of bus bar 73a, a bus bar assembly 40e with a variable length can be constructed.

[0028] In the example shown in Fig. 6, bus bar 72 has a through hole 76 and bus bar 73 has a tapped hole 77, but as in a fifth embodiment shown in Fig. 7, each of bus bars 72a and 73a may have both a through hole 76 and a tapped hole 77. This embodiment is useful when it is desired to appropriately change the insertion direction of the screw 70. Note that in the fourth embodiment as well, each bus bar may have both a through hole 76 and a tapped hole 77.

[0029] 8 shows a schematic configuration of a bus bar assembly 40f according to Example 6. The first bus bar 80 and the second bus bar 88 constituting the bus bar assembly 40f have a substantially L-shape that is roughly the same as the bus bar 42 of Example 1, but differ from Example 1 in that they have convex or concave portions arranged on concentric circles at the tip ends of the long sides.

[0030] Bus bar 80 has, at the tip of its long side portion 82, a through hole 84 through which a passing member such as bolt 52 can be inserted, and at least three (eight in the illustrated example) recessed portions or through holes 86 on a circle centered at through hole 84. On the other hand, bus bar 88 has, at the tip of its long side portion 90, a through hole 92 through which a passing member such as bolt 52 can be inserted, and at least three (eight in the illustrated example) protruding portions (columnar portions) 94 on a circle centered at through hole 92. Furthermore, the circle on which recessed portion 86 is formed and the circle on which protruding portion 94 is formed have the same diameter; that is, when through holes 84 and 86 are aligned, protruding portion 94 is housed in recessed portion 86.

[0031] With the through-holes 84 of bus bar 80 and the through-holes 92 of bus bar 88 aligned with each other, inserting members such as bolts 52 into the holes 84, 92, and then joining the two bus bars together using fastening members such as nuts 54, bus bar assembly 40f can be constructed. At this time, all eight protrusions 94 are housed in the corresponding recesses 86, so both bus bars are joined while being accurately positioned relative to each other.

[0032] Figure 9 shows a modified example of the sixth embodiment. In Figure 8, the angle between the long sides of the two bus bars is approximately 180°. However, because the recessed portions 86 and the protruding portions 94 are arranged on a circle of the same diameter, the angle can also be 90° as shown in Figure 9, or any angle in 45° increments in the illustrated example. In this case, too, all eight protruding portions 94 are accommodated in the corresponding recessed portions 86, so the two bus bars are accurately positioned relative to each other and joined. However, the number of protruding portions 94 may be fewer than the number of recessed portions 86.

[0033] 10 shows a schematic configuration of a bus bar assembly 40g according to Example 7. Example 7 is similar to Example 6, but differs in that each of the bus bars 80 and 88 has both a protrusion 94 and a recess (or through hole) 86.

[0034] Specifically, bus bar 80 has, at the tip of long side portion 82, through-hole 84 through which a through-hole member such as bolt 52 can be inserted, and at least two (four in the illustrated example) recessed portions or through-holes 86 and at least two (four in the illustrated example) protruding portions 94 are alternately arranged on a circle centered on through-hole 84. Similarly, bus bar 88 has, at the tip of long side portion 90, through-hole 92 through which a through-hole member such as bolt 52 can be inserted, and at least two (four in the illustrated example) recessed portions or through-holes 86 and at least two (four in the illustrated example) protruding portions 94 are alternately arranged on a circle centered on through-hole 92. Even with this configuration, the coupling angle between bus bars 80 and 88 can be changed depending on the number and spacing of recessed portions or through-holes 86 and protruding portions 94.

[0035] 11 shows a schematic configuration of a bus bar assembly 40h according to Example 8. The two (first and second) bus bars 96 constituting the bus bar assembly 40h have a substantially L-shape similar to the bus bar 42 of Example 1, but differ from Example 1 in that the tip of the long side of at least one bus bar is rounded.

[0036] Each bus bar 96 has a through hole 102 at the tip of its long side portion 98 through which a bolt 52 can be inserted, and is rounded at the tip 100. With the through holes 102 of the two bus bars 96 aligned, the bolt 52 is inserted into the hole 102, and the two bus bars 96 are joined together using nuts 54 or the like, thereby forming the bus bar assembly 40h.

[0037] In the eighth embodiment, as in the first embodiment, the angle θ formed by the long sides 98 of the two bus bars 96 can be set arbitrarily. However, in the first embodiment, because the long sides 44 have corners at their ends, the corners also have a constant potential when a relatively large current flows through the bus bars, which may shorten the insulation distance between the bus bars and other electronic components nearby. Furthermore, in the circuit of a motor drive device, various components, including bus bars, may be arranged quite densely, and in such cases, the corners of the bus bars may interfere with other components.

[0038] However, in the eighth embodiment, the ends of the long sides 98 are rounded, which not only reduces interference with other components but also shortens the insulation distance between the long sides 98 and the other components. As shown in Fig. 11, the connection portions of the bus bars 96 that are connected to a circuit board or the like (not shown) may also be rounded in the same manner as the ends of the long sides 98.

[0039] 12 shows a schematic configuration of a bus bar assembly 40i according to Example 9. Example 9 roughly corresponds to an assembly having three or more bus bars 42 of Example 1.

[0040] In each of the first to eighth embodiments, two bus bars are combined to form an assembly, but as in the ninth embodiment, three or more bus bars 42 can be combined as appropriate and connected to each other using fastening means such as bolts 52 and nuts 54. The ninth embodiment is useful when, for example, three or more electronic components are to be electrically connected to each other, and the combination form of the bus bars 42 (the shape of the assembly 40i) can also be changed as appropriate depending on the locations of the electronic components.

[0041] 13 shows a schematic configuration of a bus bar assembly 40j according to Example 10. Example 10 corresponds to Example 9, in which one of the bus bars is replaced with a straight bus bar.

[0042] In the tenth embodiment, a plurality of bus bars 42 (two in the illustrated example) can be coupled to a straight bus bar 104 using fastening means such as bolts 52 and nuts 54. The coupling positions of the bus bars 42 relative to the straight bus bar 104 can be set and changed as appropriate, allowing bus bar assemblies 40j of various sizes and shapes to be constructed.

[0043] The above-described embodiments can be combined as appropriate. For example, a bus bar having rounded ends at the long sides as in the eighth embodiment shown in Fig. 11 can be applied to the other embodiments.

[0044] In the above-described embodiment, bolts and nuts or screws are used as the means for connecting the bus bars to each other, but the present disclosure is not limited to this, and clamps or adhesives, for example, can also be used.

[0045] According to the present disclosure, by combining multiple bus bars in any of multiple ways, bus bar assemblies of various sizes and shapes can be constructed, significantly improving the design flexibility of the motor drive device circuit. Furthermore, according to the present disclosure, the number of bus bar types that need to be prepared can be reduced compared to conventional methods, which also reduces the number of molds required for manufacturing bus bars, thereby streamlining the manufacture of motor drive devices and reducing costs.

[0046] In order to share a common mold, it is preferable that the motor drive device has at least two bus bars of the same size and shape. In this disclosure, "having the same size and shape" with respect to multiple bus bars means that those bus bars can be manufactured using the same mold. For example, multiple bus bars that have different shapes, strictly speaking, due to drilling or other processes being performed in different locations after manufacturing using a mold, are also included in the scope of "having the same size and shape."

[0047] Although the present disclosure has been described in detail, the present disclosure is not limited to the individual embodiments described above. Various additions, substitutions, modifications, partial deletions, etc. are possible in these embodiments without departing from the gist of the present disclosure or the spirit of the present disclosure derived from the content of the claims and their equivalents. These embodiments can also be implemented in combination. For example, in the above-described embodiments, the order of each operation and the order of each process are shown as examples and are not limited to these. The same applies when numerical values ​​or mathematical expressions are used in the description of the above-described embodiments.

[0048] The following additional notes are provided regarding the above-described embodiment and modifications.

[0049] (Supplementary Note 1) A motor drive device having a busbar assembly including a first busbar and a second busbar, and a coupling means for coupling the first busbar and the second busbar to each other, wherein the first busbar, the second busbar, and the coupling means are configured such that the busbar assembly has a plurality of shapes in which at least one of the position and the attitude of the second busbar relative to the first busbar is different.

[0050] (Supplementary Note 2) The motor drive device according to Supplementary Note 1, wherein the first bus bar has a first through hole, the second bus bar has a second through hole, and the coupling means is inserted through the first through hole and the second through hole to couple the first bus bar and the second bus bar to each other.

[0051] (Supplementary Note 3) The motor drive device according to Supplementary Note 1, wherein the first bus bar has a through hole, the second bus bar has an elongated hole aligned with the through hole, and the coupling means is inserted through both the through hole and the elongated hole to couple the first bus bar and the second bus bar to each other.

[0052] (Supplementary Note 4) The motor drive device according to Supplementary Note 1, wherein the first bus bar has three or more first through holes positioned on concentric circles, the second bus bar has three or more second through holes or tapped holes positioned on concentric circles of the same diameter as the concentric circles, and the coupling means couples the first bus bar and the second bus bar to each other by inserting them through the first through holes and the second through holes or tapped holes.

[0053] (Supplementary Note 5) The motor drive device according to Supplementary Note 1, wherein the first bus bar has three or more third through holes arranged at equal intervals along its longitudinal direction, the second bus bar has three or more fourth tapped holes or through holes arranged at the same equal intervals as the through holes along its longitudinal direction, and the coupling means couples the first bus bar and the second bus bar to each other by inserting them through the third through holes and the fourth through holes or tapped holes.

[0054] (Supplementary Note 6) The motor drive device according to Supplementary Note 1, wherein the first bus bar has three or more first through holes located on concentric circles and one or more third through holes or tapped holes different from the first through holes, the second bus bar has three or more second through holes or tapped holes located on concentric circles having the same diameter as the concentric circles and one or more fourth tapped holes or through holes different from the second through holes, and the coupling means couples the first bus bar and the second bus bar to each other by inserting them through the third through holes or tapped holes and the fourth tapped holes or through holes.

[0055] (Supplementary Note 7) The motor drive device according to Supplementary Note 2, wherein the first bus bar has three or more recesses located on concentric circles centered on the first through hole, and the second bus bar has three or more protrusions located on the same diameter as the concentric circles centered on the second through hole and fitting into the recesses.

[0056] (Supplementary Note 8) The motor drive device according to Supplementary Note 2, wherein the first bus bar has two or more recesses and two or more protrusions located on a concentric circle centered on the first through hole, and the second bus bar has two or more protrusions and two or more recesses located on a concentric circle of the same diameter as the concentric circle centered on the second through hole.

[0057] (Supplementary Note 9) The motor drive device according to any one of Supplementary Notes 1 to 8, wherein a tip of at least one of the first bus bar and the second bus bar is rounded.

[0058] (Supplementary Note 10) The motor drive device according to Supplementary Note 1, further comprising a third bus bar, and further comprising coupling means for coupling the third bus bar to the first bus bar or the second bus bar.

[0059] (Supplementary Note 11) The motor drive device according to Supplementary Note 1, further comprising a straight bus bar, and further comprising coupling means for coupling the straight bus bar to the first bus bar or the second bus bar.

[0060] (Supplementary Note 12) The motor drive device according to Supplementary Note 1, wherein the first bus bar and the second bus bar have the same size and shape.

[0061] (Supplementary Note 13) The motor drive device according to any one of Supplementary Notes 1 to 12, wherein the connecting means is a combination of a bolt and a nut, or a screw.

[0062] 2 Motor 10 Motor drive device 12 Housing 14 Flange 16 Fan 18 Connector 20 Input terminal 22 Output terminal 24 Diode 26 Capacitor 28 Inverter 30 Input section 32 DC link section 34 Output section 40a-40j Bus bar assembly 42, 56, 64, 65, 72, 73, 80, 88, 96 Bus bar 44, 58, 66, 67, 74, 75, 82, 90, 98 Long side section 46 Short side section 48 Connection section 50, 68a, 68b, 76, 84, 92, 102 Through hole 52 Bolt 54 Nut 60 Slot 70 Screw 77 Tapped hole 86 Concave section 94 Convex section 100 Tip 104 Straight bus bar

Claims

1. A motor drive device having a busbar assembly including a first busbar and a second busbar, and a coupling means for coupling the first busbar and the second busbar to each other, wherein the first busbar, the second busbar and the coupling means are configured such that the busbar assembly has a plurality of shapes in which at least one of the position or attitude of the second busbar relative to the first busbar is different.

2. The motor drive device of claim 1, wherein the first bus bar has a first through hole, the second bus bar has a second through hole, and the coupling means passes through the first through hole and the second through hole to couple the first bus bar and the second bus bar to each other.

3. The motor drive device of claim 1, wherein the first bus bar has a through hole and the second bus bar has a long hole aligned with the through hole, and the coupling means passes through both the through hole and the long hole to couple the first bus bar and the second bus bar to each other.

4. The motor drive device of claim 1, wherein the first bus bar has three or more first through holes positioned on a concentric circle, the second bus bar has three or more second through holes or tapped holes positioned on a concentric circle of the same diameter as the concentric circle, and the connecting means connects the first bus bar and the second bus bar to each other by inserting them through the first through holes and the second through holes or tapped holes.

5. The motor drive device of claim 1, wherein the first bus bar has three or more third through holes arranged at equal intervals along its longitudinal direction, the second bus bar has three or more fourth tapped holes or through holes arranged at the same equal intervals as the third through holes along its longitudinal direction, and the coupling means couples the first bus bar and the second bus bar to each other by inserting the third through holes and the fourth tapped holes or through holes.

6. The motor drive device of claim 1, wherein the first bus bar has three or more first through holes located on a concentric circle and one or more third through holes or tapped holes different from the first through holes, the second bus bar has three or more second through holes or tapped holes located on a concentric circle of the same diameter as the concentric circle and one or more fourth tapped holes or through holes different from the second through holes, and the coupling means couples the first bus bar and the second bus bar to each other by inserting them through the third through holes or tapped holes and the fourth tapped holes or through holes.

7. A motor drive device as described in claim 2, wherein the first bus bar has three or more recesses located on a concentric circle centered on the first through hole, and the second bus bar has three or more protrusions located on a concentric circle of the same diameter as the concentric circle centered on the second through hole and fitting into the recesses.

8. A motor drive device as described in claim 2, wherein the first bus bar has two or more recesses and two or more protrusions located on a concentric circle centered on the first through hole, and the second bus bar has two or more protrusions and two or more recesses located on a concentric circle of the same diameter as the concentric circle centered on the second through hole.

9. The motor drive device according to any one of claims 1 to 8, wherein a tip of at least one of the first bus bar or the second bus bar is rounded.

10. The motor drive apparatus of claim 1, further comprising a third bus bar, and further comprising coupling means for coupling said third bus bar to said first bus bar or said second bus bar.

11. The motor drive device of claim 1, further comprising a straight bus bar, and further comprising coupling means for coupling said straight bus bar to said first bus bar or said second bus bar.

12. The motor drive device of claim 1, wherein the first bus bar and the second bus bar are identical in size and shape to each other.

13. The motor drive device according to any one of claims 1 to 12, wherein the connecting means is a combination of a bolt and a nut, or a screw.

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