Power conversion device

Abstract

A power conversion device according to the present invention comprises: at least one power module for power conversion; a plurality of bus bars that are welded and connected to the terminals of the power module; current sensors that detect currents flowing through the plurality of bus bars; a chassis to which the power module and the current sensors are fixed; and a bus bar holder that engages the plurality of bus bars with the current sensors and enables the plurality of bus bars to move at least in a direction of connection to the power module and in an arrangement direction of the current sensors.

Description

Power Conversion Device

[0001] The present invention relates to a power conversion device.

[0002] For example, Patent Document 1 listed below discloses a power conversion device in which the power module and control board are positioned in a connection circuit unit housing that integrates DC and AC bus bars and AC sensors positioned in a case, thereby absorbing variations and improving the positioning accuracy of AC bus bars and the like that are connected to the outside, compared to a method in which parts are positioned based on the power module, thereby improving assembly ease and realizing a smaller inverter.

[0003] Patent No. 7005732

[0004] In the technology described in Patent Document 1, for example, if the AC bus bar connected to the terminal on the power module side is fixed in a state in which the terminals are uneven, a gap may occur between the connecting terminals, which may result in poor welding. In view of this, an object of the present invention is to provide a power conversion device that aims to stabilize welding quality and reduce size.

[0005] The power conversion device of the present invention comprises at least one power module for power conversion, a plurality of bus bars welded to terminals of the power module, a current sensor that detects current flowing through the plurality of bus bars, a housing to which the power module and the current sensor are fixed, and a bus bar holder that engages the plurality of bus bars with the current sensor and enables the plurality of bus bars to move at least in the direction in which they are connected to the power module and in the direction in which the current sensors are arranged.

[0006] According to the present invention, it is possible to provide a power conversion device that aims to stabilize welding quality and reduce size.

[0007] FIG. 1 is a diagram illustrating components of a power converter according to an embodiment of the present invention; FIG. 2 is a cross-sectional view of a power converter with the components of FIG. 1 stored therein; FIG. 3 is a diagram illustrating a PMAC bus bar and AC sensor sub-assembly according to an embodiment of the present invention; and FIG. 4 is a cross-sectional view of a PMAC bus bar and AC sensor sub-assembly according to an embodiment of the present invention.

[0008] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. The following description and drawings are examples for explaining the present invention, and some omissions and simplifications have been made as appropriate for clarity of explanation. The present invention can be implemented in various other forms. Unless otherwise specified, each component may be singular or plural.

[0009] In order to facilitate understanding of the invention, the position, size, shape, range, etc. of each component shown in the drawings may not represent the actual position, size, shape, range, etc. Therefore, the present invention is not necessarily limited to the position, size, shape, range, etc. disclosed in the drawings.

[0010] (One embodiment and overall configuration) (FIG. 1) The power conversion device 100 has a power module 4 for power conversion, an EMC filter 8, a control board 12, a sub-assembly including a PMAC bus bar 6a and an AC sensor 5, an HVAC bus bar 6b ​​which is an AC line circuit component, a DC molded bus bar 9 which is a DC line circuit component, and a case 10. The case 10 houses the above components and forms a flow path forming body therein.

[0011] The PMAC bus bars 6a are a plurality of bus bars welded to the terminals of the power modules 4. The AC sensors 5 detect the current flowing through the PMAC bus bars 6a and are fixed to the case 10 with screws or bolts. The AC sensors 5 are combined with the PMAC bus bars 6a to function as an integrated sub-assembly.

[0012] The HVAC bus bar 6b ​​is fixed to the case 10 with screws or bolts. The PMAC bus bar 6a is screwed to the HVAC bus bar 6b, thereby electrically connecting the HVAC bus bar 6b ​​and the PMAC bus bar 6a. The bus bar portion of the HVAC bus bar 6b ​​that extends upward in the drawing and is not connected to the PMAC bus bar 6a is connected to the motor.

[0013] The control board 12 is a GD (Gate Drive) board that controls the power module 4, and is fixed to the case 10. The control board 12 also has a GD board connector (not shown), to which signal pins of the AC sensor 5 and terminals of the power module 4 are electrically connected.

[0014] The power module 4 is fixed to the case 10 with bolts and mounted on top of the control board 12. The power module 4 is also electrically connected to a GD board connector provided on the control board 12. The power module 4 is also connected to the PMAC bus bar 6a and the DC molded bus bar 9 by welding.

[0015] The power module 4 has a terminal on the side that connects to the PMAC bus bar 6a and a gate-side welding terminal that is the terminal opposite the terminal that connects to the PMAC bus bar 6a. The positioning of the components mounted in the case 10 is adjusted based on the gate-side welding terminal. The present invention allows the position of the PMAC bus bar 6a within the case 10 to be adjusted, taking into account the welding connection to the power module 4 and the connection to the HVAC bus bar 6b.

[0016] The position-adjusted PMAC bus bar 6a is bolted to the HVAC bus bar 6b ​​without any variation in connection with the power module 4, improving the quality of the welding connection performed in the subsequent process.

[0017] Although the power conversion device 100 is shown as having one power module 4 mounted thereon, two power modules 4 may be mounted thereon.

[0018] (FIG. 2) The control board 12 is fixed to the case 10. The control board 12 is electrically connected to the terminals of the power module 4 extending to the control board 12, the AC sensor terminal 5a, and a board power harness (not shown).

[0019] The power module terminals 15 are electrically connected to the terminals of the PMAC bus bars 6a by welding.

[0020] (FIG. 3) Fig. 3(a) is a diagram showing a bus bar holder 19 having a PMAC bus bar 6a fixed to an AC sensor 5. Fig. 3(b) is an explanatory diagram of the PMAC bus bar 6a and the bus bar holder 19.

[0021] The PMAC bus bar 6a has a bent terminal 24 connected to the power module 4 (FIG. 1), and a core insertion terminal 21 facing the bent terminal 24 and inserted into the annular magnetic core 16 from the power module 4 side.

[0022] The busbar holder 19 inserts the PMAC busbar 6a into the through-hole of the magnetic core 16 of the AC sensor 5 in the insertion direction 23. The AC sensor 5 having the magnetic core 16 has a structure for engaging with the busbar holder 19, and the PMAC busbar 6a is engaged with the busbar holder 19 by being inserted into the magnetic core 16. In this way, the AC sensor 5 and the PMAC busbar 6a become an integrated sub-assembly.

[0023] The PMAC bus bar 6a is a three-phase bus bar (U, V, and W) integrated with molded resin. The magnetic core 16 is molded to prevent rust. The PMAC bus bar 6a also has an extension 18 that is inserted into and molded into the magnetic core 16. The molded and sealed portion of the extension 18 prevents the terminals of each phase of the PMAC bus bar 6a from tilting. It also helps prevent the snap-fit ​​structure from coming loose.

[0024] The bus bar holder 19 has protrusions 11 between the bus bars of the PMAC bus bars 6a. The protrusions 11 protrude in a direction to be connected to the power module 4 and in a direction perpendicular to the arrangement direction of the AC sensors 5 (upward in the drawing). The protrusions 11 are held by equipment (not shown) to move the PMAC bus bars 6a inserted through the magnetic cores 16 toward the power modules 4 for position adjustment, thereby improving the positional accuracy of the terminals on the side connecting to the power modules 4 and improving the reliability of the welded connection.

[0025] Such position adjustment can also be achieved by forming and using something other than the protrusion 11. For example, adjustment can be made by providing a bent portion or a groove portion instead of the protrusion 11, which makes it possible to both relieve stress on the busbar holder 19 and prevent sink marks during molding.

[0026] The busbar holder 19 includes a stress relief portion 2. The stress relief portion 2 can relieve stress concentration on the busbar holder 19 when the AC sensor 5, with which the busbar holder 19 engages, is fixed to the case 10. The stress relief portion 2 also has a thickness relief effect, preventing sink marks during molding of the busbar holder 19, which is formed to be thick, and can prevent distortion of the busbar holder 19 and PMAC busbar 6a due to the occurrence of sink marks, thereby preventing variations in the welded connection between the PMAC busbar 6a and the power module 4.

[0027] The AC bus bar hole 7 of the PMAC bus bar 6 a is a connection and fixing hole for the HVAC bus bar 6 b, but has a hole diameter larger than the size required for connection. This allows for absorbing variations in the connection positions of the PMAC bus bar 6 a and the HVAC bus bar 6 b, even if a sink mark occurs in the bus bar holder 19, and improves welding quality.

[0028] The PMAC bus bar 6a has a bent terminal 24 as a terminal to be welded to the power module 4. The terminal 15 (see FIG. 2) to be welded to the PMAC bus bar 6a in the power module 4 is bent in the same direction as the bent terminal 24. Therefore, the bent terminals can be welded to each other by abutting the tips of the bent terminals against each other. The welded connection between the bent terminal 24 and the power module terminal 15 is achieved by, for example, TIG welding.

[0029] Regarding the size of the through hole of the magnetic core 16, when inserting the PMAC bus bar 6a, it is not necessary to insert the bent terminal 24 of the PMAC bus bar 6a, so there is no need to unnecessarily enlarge the through hole of the magnetic core 16. As a result, the mounting portion of the magnetic core 16 in the AC sensor 5 combined with the magnetic core 16 can be made smaller, contributing to cost reduction.

[0030] (Fig. 4) Fig. 4(a) is a plan view of the sub-assembly of the PMAC bus bar 6a and AC sensor 5, and Fig. 4(b) is a cross-sectional view taken along line B-B of Fig. 4(a). The AC sensor 5 has a hole 14, and the bus bar holder 19 has a claw 13. The claw 13 engages with the hole 14, thereby forming an integrated sub-assembly of the PMAC bus bar 6a and AC sensor 5.

[0031] When engaging with the hole 14, the claw 13 needs to climb over the climbing portion 14a once, but stress is only applied to the claw 13 at this time, and since a clearance is provided in the engaged portion as a movement allowance, no stress is applied to the claw 13 after engagement. Because the AC sensor 5 is fixed to the case 10, the PMAC bus bar 6a can use this clearance to push the protrusion 11 from the direction opposite to the side where the PMAC bus bar 6a is inserted into the magnetic core 16 (see FIG. 3), thereby making it possible to adjust the position for welding connection with the power module 4.

[0032] In this way, even when variations in position and size are taken into account, the engagement portion between the claw portion 13 and the hole portion 14 does not come into contact with the inner wall of the hole portion 14 of the AC sensor 5, so the busbar holder 19 can move the PMAC busbar 6a at least in the direction in which it is connected to the power module 4 and in the direction in which the AC sensor 5 (magnetic core 16) is arranged.

[0033] When the PMAC busbar 6a is combined with the AC sensor 5, the busbar holder 19 has a gap 17 between it and the magnetic core 16 in the direction in which the core insertion terminal 21 is inserted into the magnetic core 16. This gap 17 is created when the PMAC busbar 6a is adjusted to the terminal 15 of the power module 4, and in combination with the clearance structure provided between the claw portion 13 and the hole portion 14 described above, it is possible to optimize the movable distance. In addition, by moving the PMAC busbar 6a toward the power module 4 so as to create the gap 17, it is possible to adjust the busbar tip of the PMAC busbar 6a on the HVAC busbar 6b ​​side so that it does not hit the busbar wall of the HVAC busbar 6b.

[0034] The busbar holder 19 has the claws 13 that are as long as possible and have rounded bases to relieve stress.

[0035] As described above, the present invention absorbs the tolerances of the PMAC bus bar 6 a, the power module 4, and the HVAC bus bar 6 b and improves the accuracy of component placement, thereby achieving miniaturization and enabling compatibility with automated assembly lines. This improves the ease of assembly and welding accuracy of the power conversion device 100, and furthermore, makes it possible to achieve stable welding connections and low costs without providing fixing points on the PMAC bus bar 6 a.

[0036] According to the embodiment of the present invention described above, the following advantageous effects are achieved.

[0037] (1) The power conversion device 100 of the present invention includes at least one power module 4 for power conversion, a plurality of bus bars 6a connected by welding to terminals 15 of the power module 4, a current sensor 5 that detects current flowing through the plurality of bus bars 6a, a housing 10 to which the power module 4 and the current sensor 5 are fixed, and a bus bar holder 19 that engages the plurality of bus bars 6a with the current sensor 5 and enables movement of the plurality of bus bars 6a at least in the direction in which they are connected to the power module 4 and in the direction in which the current sensors 5 are arranged. In this way, a power conversion device 100 can be provided that aims to stabilize welding quality and reduce size.

[0038] (2) The busbar holder 19 has protrusions 11 between the plurality of busbars 6a, which protrude in the direction in which the busbars 6a are connected to the power modules 4 and in a direction perpendicular to the arrangement direction of the current sensors 5. This allows the position of the PMAC busbars 6a to be adjusted relative to the power modules 4.

[0039] (3) The busbar holder 19 has the stress relief portions 2 at positions between the busbars and the protrusions, respectively. This prevents the busbar holder 19 from generating sink marks during molding and suppresses distortion.

[0040] (4) A control board 12 that controls the power module 4 is provided, and the control board 12 is fixed to the housing 10. In this way, based on the prerequisite that the control board 12 is fixed to the case 10, the power conversion device 100 of the present invention can be realized, which aims to stabilize welding quality and reduce size.

[0041] (5) The busbar holder 19 has the claws 13, and the current sensor 5 has the holes 14 into which the claws 13 are engaged, and when the claws 13 are engaged in the holes 14, they do not come into contact with the inner walls of the holes 14. This allows the position of the PMAC busbar 6a to be adjusted relative to the power module 4 without being affected by stress.

[0042] (6) The current sensor 5 has an annular magnetic core 16, and the bus bars 6a have bent terminals 24 that are welded to the terminals of the power module 4 and core insertion terminals 21 that face the bent terminals 24 and are inserted into the magnetic core 16 from the power module 4 side, and the terminals 15 of the power module 4 and the bent terminals 24 are abutted against each other and welded to each other. This contributes to miniaturization and cost reduction.

[0043] (7) The busbar holder 19 has a gap 17 between it and the magnetic core 16 in the direction in which the core insertion terminal 21 is inserted into the magnetic core 16. This configuration improves assembly efficiency and welding accuracy.

[0044] (8) The portions of the bus bars 6a that are inserted into the magnetic core 16 are molded. This prevents the PMAC bus bars 6a from tilting and prevents the engaging portions from coming loose, improving welding accuracy.

[0045] The present invention is not limited to the above-described embodiments, and various modifications and combinations of other configurations are possible without departing from the spirit of the present invention. Furthermore, the present invention is not limited to those having all of the configurations described in the above-described embodiments, and includes those in which some of the configurations are omitted.

[0046] 2 Stress relief portion 4 Power module 5 AC sensor 5a AC sensor terminal 6 Bus bar 6a PMAC bus bar 6b ​​HVAC bus bar 7 AC bus bar hole 8 EMC filter 9 DC molded bus bar 10 Case 11 Protrusion 12 Control board 13 Claw portion 14 Hole portion 14a Overhang portion 15 Power module terminal 16 Magnetic core 17 Gap 18 Extension portion 19 Bus bar holder 21 Core insertion terminal 23 Insertion direction 24 Bent terminal 100 Power conversion device

Claims

1. A power conversion device comprising: at least one power module for power conversion; a plurality of bus bars connected by welding to terminals of the power module; a current sensor for detecting current flowing through the plurality of bus bars; a housing to which the power module and the current sensor are fixed; and a bus bar holder for engaging the plurality of bus bars with the current sensor and enabling the plurality of bus bars to move at least in the direction in which they are connected to the power module and in the direction in which the current sensor is arranged.

2. The power conversion device according to claim 1, wherein the bus bar holder has protrusions that protrude between the plurality of bus bars in a direction in which the bus bar holder is connected to the power module and in a direction perpendicular to the arrangement direction of the current sensors.

3. The power conversion device according to claim 2, wherein the bus bar holder has stress relief portions at positions between the plurality of bus bars and the protruding portion.

4. The power conversion device according to claim 1, further comprising a control board for controlling the power module, the control board being fixed to the housing.

5. The power conversion device according to claim 1, wherein the busbar holder has a claw portion, the current sensor has a hole portion into which the claw portion engages, and the claw portion does not contact an inner wall of the hole portion when engaged with the hole portion.

6. The power conversion device according to claim 5, wherein the current sensor has an annular magnetic core, the plurality of bus bars have bent terminals which are welded to terminals of the power module, and core insertion terminals which face the bent terminals and are inserted into the magnetic core from the power module side, and the terminals of the power module and the bent terminals are abutted against each other and welded to each other.

7. The power conversion device according to claim 6, wherein the busbar holder has a gap between it and the magnetic core in a direction in which the core insertion terminal is inserted into the magnetic core.

8. The power conversion device according to claim 7, wherein the portions of the plurality of bus bars that are inserted into the magnetic core are molded.

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