Current detector core member, current detector, and power conversion device

Abstract

A core member of a current detector provided with an annular core having a magnetic gap, a first molding portion that seals a portion of the core, and a second molding portion that seals the first molding portion, wherein: the first molding portion has a pair of pressing surfaces sandwiching the magnetic gap; and the pair of pressing surfaces are sealed by the second molding portion.

Description

[Technical Field]

[0001] The present invention relates to a core member for a current detector, a current detector, and a power conversion device. [Background technology]

[0002] A power conversion device that converts direct current to alternating current includes a current detector that detects the current flowing through a bus bar. The current detector measures the magnetic flux generated by the current flowing through the bus bar using a core through which the bus bar is inserted and an electromagnetic conversion element disposed in the magnetic gap of the core. In particular, in a power conversion device for a vehicle that requires reliability, the core that constitutes the current detector must be mounted with high precision and vibration resistance.

[0003] Patent document 1 discloses a current detector in which a core component is composed of a core and a molded resin portion that is molded at one or more locations along the magnetic path of the core and covers the surface of the core, and the core component is fixed inside the outer case with the surface of the molded resin portion in contact with the inner surface of the outer case. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2011-153935 Summary of the Invention [Problem to be solved by the invention]

[0005] The current detector described in Patent Document 1 has problems with accuracy and vibration resistance in mounting the core. [Means for solving the problem]

[0006] The core member of the current detector according to the present invention comprises: an annular core having a magnetic gap; With the magnetic gap between them A part of the core each seal a paira first molded portion and a second molded portion that seals the first molded portion, a pair The first mold section is Each of the pair of first molded parts has a substantially rectangular parallelepiped shape, and at least one surface of each of the pair of first molded parts is A pair of pressing surfaces sandwiching the magnetic gap Formation The pair of pressing surfaces are sealed by the second mold portion, and the core and the first mold portion protrude from an end surface of the second mold portion. [Effects of the Invention]

[0007] According to the present invention, a highly reliable current detector having high accuracy and vibration resistance in core mounting can be provided. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 2 is a circuit configuration diagram of a power conversion device. [Figure 2] FIG. 2 is a perspective view of the appearance of the current detector. [Figure 3] (A) (B) (C) Side view, top view, and cross-sectional view of the current detector. [Figure 4] FIG. 2 is an enlarged cross-sectional view of a portion of the current detector. [Figure 5] 1A and 1B are an external perspective view and a side view showing the first molded part sealing a part of the core. [Figure 6] 1A and 1B are external perspective views showing a core member. [Figure 7] FIG. 10 is an external perspective view showing a first molded portion according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] 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.

[0010] 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.

[0011] FIG. 1 is a circuit configuration diagram of a power conversion device 100. As shown in FIG. The power conversion device 100 converts DC power from the battery 200 into AC power to drive the motor 300. Furthermore, when the motor 300 is rotated by an external force and functions as a generator, the power conversion device 100 converts the generated AC power into DC power to charge the battery 200. The battery 200 is a rechargeable secondary battery, and a DC voltage is applied to the power conversion device 100 via DC bus bars B1 and B2 connected to the positive and negative electrodes of the battery 200. The motor 300 is, for example, a three-phase synchronous motor having three-phase windings therein. Three-phase AC currents output from the power conversion device 100 via AC bus bars Bu, Bv, and Bw flow through the windings of each phase of the motor 300.

[0012] The power conversion device 100, the battery 200, and the motor 300 are mounted on, for example, a vehicle, and a vehicle control device 400 also mounted on the vehicle outputs to the power conversion device 100 a torque command for the motor 300 and the like.

[0013] The power conversion device 100 includes a capacitor 500, an inverter 600, a current detector 700, and a control unit 800.

[0014] The capacitors 500 include a noise removal capacitor and a smoothing capacitor. The inverter 600 has three-phase switching legs connected between the DC bus bars B1 and B2, and each switching leg is composed of an upper arm switching element and a lower arm switching element. The power semiconductor elements are, for example, IGBTs (Insulated Gate Bipolar Transistors) and MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). The inverter 600 converts DC power and AC power mutually.

[0015] The current detector 700, which will be described in detail later, measures the magnetic flux generated by the current flowing through the AC bus bars Bu, Bv, and Bw using a core through which the AC bus bars Bu, Bv, and Bw are inserted and an electromagnetic conversion element disposed in the magnetic gap of the core, thereby determining the current value. Note that, in this embodiment, an example will be described in which the AC bus bars Bu, Bv, and Bw are inserted into the core, but a DC bus bar for transmitting DC power may also be inserted into the core.

[0016] The control unit 800 controls the drive of the inverter 600 to achieve optimal control and optimal efficiency in accordance with the torque command output from the vehicle control device 400, based on the current value detected by the current detector 700, the rotation angle of the motor 300 detected by a resolver or the like installed in the motor 300, and the input voltage value (not shown) from the battery 200. This control aims to improve vehicle behavior, such as response and operability. In other words, providing a highly reliable current detector 700 as shown in this embodiment, which suppresses deterioration of magnetic characteristics and has high detection accuracy and vibration resistance, can be expected to improve vehicle behavior and the efficiency of the motor 300.

[0017] FIG. 2 is a perspective view of the appearance of the current detector 700. As shown in FIG. Core member 750 of current detector 700 includes an annular core 730 having a magnetic gap M, a first molded portion 710 that seals a portion of core 730, and a second molded portion 720 that seals first molded portion 710. First molded portion 710 and second molded portion 720 are formed by sealing a molding resin such as an insulating synthetic resin within a mold.

[0018] First mold section 710, details of which will be described later, seals a portion of core 730. Second mold section 720 seals a portion of first mold section 710 so as to connect three phase core members 750. AC bus bars Bu, Bv, and Bw are inserted into each of core members 750 for three phases. A circuit board 760 is installed on the upper surface of second mold section 720.

[0019] An electromagnetic transducer element disposed within magnetic gap M of core 730 is mounted on circuit board 760, and circuit board 760 is fixed to second molded section 720 by thermal caulking using resin bosses 762 formed at three locations on second molded section 720. Bosses 762 also serve to position circuit board 760 relative to second molded section 720, and positioning circuit board 760 by bosses 762 determines the position from magnetic gap M to electromagnetic transducer element 740 (see FIG. 3(C)) mounted on circuit board 760. Note that circuit board 760 may be fixed to second molded section 720 using a fastening member such as a screw instead of boss 762. Circuit board 760 has a connector 763, and a voltage value based on a detection value measured by the electromagnetic transducer element is output to control section 800 via connector 763.

[0020] Current detector 700 is configured by integrally fixing core 730, first molded part 710, and circuit board 760 to second molded part 720. Current detector 700 is fixed to the housing of power conversion device 100 by screwing collars 764 to both ends of second molded part 720 while being positioned by positioning pins 780 (see FIG. 3).

[0021] 3(A), 3(B), and 3(C) are a side view, a top view, and a cross-sectional view of the current detector 700. Fig. 3(A) is a side view, Fig. 3(B) is a top view, and Fig. 3(C) is a cross-sectional view taken along line BB in Fig. 3(B).

[0022] As shown in FIG. 3A, core 730 and first molded section 710 protrude from a lower end surface 721 of second molded section 720. As shown in FIG. 3B, circuit board 760 is fixed to a board mounting surface 722, which is the upper end surface of second molded section 720, by bosses 762 at three locations. As shown in FIG. 3C, circuit board 760 has an electromagnetic transducer 740 mounted thereon and is disposed within the magnetic gap of core 730. That is, second molded section 720 has board mounting surface 722 on which circuit board 760 is mounted, and also has grooves 724 recessed from board mounting surface 722 toward the magnetic gap, and electromagnetic transducer 740 is accommodated in grooves 724. Note that, although an example in which electromagnetic transducer 740 is mounted on circuit board 760 has been shown in this embodiment, it is also possible to omit circuit board 760 by mounting electromagnetic transducer 740 on control section 800.

[0023] The current detector 700 is fixed to the housing of the power conversion device 100 (not shown), but since the power conversion device 100 for vehicles operates at a high voltage, it is necessary to ensure a safe insulation distance, and the current detector 700 is fixed to the housing of the power conversion device 100 while ensuring the necessary insulation distance.

[0024] Fig. 4 is a partially enlarged cross-sectional view of the current detector 700. Fig. 4 is an enlarged view of the current detector 700 near the AC bus bar Bv of the current detector 700 shown in Fig. 3(C).

[0025] Core 730 is a wound core formed by spirally winding a magnetic strip. The wound core is made by rolling and gluing a magnetic strip, then cutting it. The wound core uses a grain-oriented electromagnetic steel sheet as the magnetic strip, which has superior magnetic properties, such as linearity, compared to non-oriented electromagnetic steel sheet. It can also achieve a high magnetic flux density and be made more compact. However, winding the magnetic strip tends to cause variations in the dimensions of core 730. Therefore, in this embodiment, first molded section 710 is molded larger than the outer shape of core 730, and this is then sealed with second molded section 720 to accommodate variations in the dimensions of core 730.

[0026] Furthermore, first molded section 710 is composed of a pair of molded sections that each seal a portion of core 730 that sandwiches magnetic gap M. That is, first molded section 710 molds the magnetic gap M side, which has less magnetic flux saturation, avoiding magnetic flux saturation section N of core 730. Magnetic flux saturation section N is located on the opposite side of AC bus bar Bv from the position of magnetic gap M of core 730, and the magnetic flux density of magnetic flux saturation section N decreases due to external stress applied to this portion. In this embodiment, first molded section 710, and further, second molded section 720 are not formed in magnetic flux saturation section N, so that stress during molding and external force after molding can be prevented from being applied to magnetic flux saturation section N, suppressing deterioration of magnetic properties and providing a current detector 700 with high detection accuracy.

[0027] 4, first mold part 710 has a pair of pressing surfaces 711 sandwiching a magnetic gap M. Second mold part 720 has pressing parts 723 that face pressing surfaces 711 of first mold part 710, and pressing parts 723 press down on parts of pressing surfaces 711 of first mold part 710. In other words, the pair of pressing surfaces 711 are sealed together while being pressed down by pressing parts 723 of second mold part 720.

[0028] More specifically, the pair of pressing surfaces 711 are outer surfaces of the pair of molded sections opposite the magnetic gap M side, and are formed outside the outer shape of the core 730. The pair of pressing surfaces 711 sandwiching the magnetic gap M press the core 730 via the first molded section 710 with the pressing section 723 during molding of the second molded section 720. This allows for accurate positioning of the magnetic gap M relative to the second molded section 720 and prevents dimensional fluctuations in the magnetic gap M, thereby providing a highly accurate current detector 700. In other words, this prevents fluctuations in the size of the magnetic gap M due to external forces, aging, and other factors. The pressing surfaces 711 are set to face the direction in which the core 730 moves. The example in FIG. 4 shows a case in which the core 730 tends to expand outward, widening the magnetic gap M.

[0029] Pressing surface 711 is not limited to the outer surface on the side opposite to magnetic gap M, but can be set on any surface that suppresses the deformation direction of core 730, such as the magnetic gap M side, the top surface, or the bottom surface. By sealing and fixing pressing surface 711 with pressing portion 723 of second molded portion 720 opposite pressing surface 711, it is possible to suppress deformation of core 730 in the direction of expanding / contracting magnetic gap M and rattle of core 730. Pressing portion 723 improves the positional accuracy of core 730 and the positional accuracy of circuit board 760 relative to core 730.

[0030] A pair of pressing surfaces 711 of first mold section 710 are exposed from the area where first mold section 710 is sealed by second mold section 720. These exposed portions are intended to be held with a jig or the like while core 730 is molded using first mold section 710, and then the next step, molding second mold section 720, is performed. This step can reduce dimensional variations (gap widening) during molding of magnetic gap M, thereby reducing variations in magnetic characteristics. It can also prevent external force from being applied by a jig or the like to magnetic flux saturation section N of core 730.

[0031] Variations in the magnetic properties of core 730 are affected by fluctuations in magnetic gap M. In this embodiment, second mold section 720 presses a portion of pressing surface 711 of first mold section 710 with pressing section 723, thereby integrally sealing first mold section 710 with second mold section 720. Furthermore, second mold section 720 seals first mold section 710 so as to connect three phases of core members 750. This configuration provides a robust structure that suppresses fluctuations in magnetic gap M. Therefore, it is possible to provide a highly reliable current detector that suppresses fluctuations in magnetic gap M due to vehicle vibrations, etc., and has high accuracy and vibration resistance.

[0032] 5(A) and 5(B) are an external perspective view and a side view showing first molded section 710 that seals a part of core 730. Fig. 5(A) is an external perspective view, and Fig. 5(B) is a side view.

[0033] As shown in FIGS. 5A and 5B, core 730 is fixed with molding resin when first molded section 710 is molded. Furthermore, as shown in FIG. 4, a portion of first molded section 710 is fixed with molding resin when second molded section 720 is molded. Therefore, compared to fixing core 730 with screws or a fitting structure, no additional structure is required to fix core 730. There is no risk of core 730 loosening due to wear of the fixing structure, and vibration resistance is excellent. Furthermore, because the fitting structure is not required, the current detector 700 in which core 730 is mounted can be miniaturized, layout flexibility within power conversion device 100 is improved, and integration of circuit board 760 and control unit 800 is facilitated. Furthermore, because the magnetic flux unsaturated portion is sealed with resin, there is no degradation of magnetic properties.

[0034] Furthermore, first molding section 710 seals a portion of core 730 without covering the entire core 730. In addition, as shown in Fig. 3(C), a portion of first molding section 710 is fixed with molding resin when second molding section 720 is molded. Therefore, the amount of molding resin used for sealing can be reduced, and current detector 700 can also be made smaller.

[0035] As shown in FIGS. 5A and 5B, a pair of pressing surfaces 711 of first molded section 710 are provided with recesses 712 in the direction of thickness D of core 730. As shown in the cross-sectional views of FIGS. 3C and 4, the molding resin that forms second molded section 720 fills these recesses 712 during molding of second molded section 720, firmly securing first molded section 710 and second molded section 720 together. That is, the pair of pressing surfaces 711 press core 730 via first molded section 710 during molding of second molded section 720, thereby enabling accurate dimensional fluctuations in magnetic gap M and positioning of magnetic gap M relative to second molded section 720. Furthermore, the anchor effect of recesses 712 between first molded section 710 and second molded section 720 provides a strong bond, making this core suitable for use in vehicles where durability and reliability are required.

[0036] Although the example in which the recesses 712 are provided in the direction of the thickness D of the core 730 has been described, they may also be provided in a direction perpendicular to the direction of the thickness D of the core 730. Furthermore, they may be provided in the direction of the thickness D of the core 730 and in a direction perpendicular to the direction of the thickness D of the core 730, i.e., in a cross shape. Furthermore, instead of being limited to recesses 712, they may be made into protrusions and provided in at least one direction of the direction of the thickness D of the core 730 or a direction perpendicular to the direction of the thickness D of the core 730. Furthermore, recesses and protrusions may be provided in combination.

[0037] Figures 6(A) and 6(B) are external perspective views showing the core member 750. Figure 6(B) is an external perspective view seen from below the external perspective view shown in Figure 6(A).

[0038] As shown in FIGS. 6A and 6B, core member 750 of current detector 700 includes an annular core 730, a first mold section 710, and a second mold section 720. First mold section 710 seals a portion of core 730. Second mold section 720 connects the three cores 730 sealed in first mold section 710 and seals the entire first mold section 710. As shown in FIG. 6B, a portion of first mold section 710 is exposed from the area sealed by second mold section 720. Second mold section 720 positions and seals first mold section 710, which seals a portion of core 730, during molding, thereby maintaining high accuracy in core positioning. Then, as described above, current detector 700 is fixed to the housing of power conversion device 100 by screwing collars 764 onto both ends of second molded section 720 while being positioned by positioning pins 780, and because positioning pins 780 are also formed when second molded section 720 is molded, this results in improved accuracy in the attachment position of current detector 700. Note that although the example in which positioning pins 780 are molded simultaneously with the molding of second molded section 720 has been described, screws may also be molded simultaneously with the molding of second molded section 720, and the attachment position of current detector 700 may be determined by these screws, with the same effect being achieved in this case.

[0039] In the above description, the second molded section 720 is configured to connect three cores 730 sealed in the first molded section 710 to integrally seal the first molded section 710, but the number of connected cores 730 sealed in the first molded section 710 is not limited and can be set as appropriate.

[0040] FIG. 7 is a perspective view showing the appearance of a first molded section 710' according to a modified example. In this modification, the pair of pressing surfaces 711 are outer surfaces of the pair of molded portions that are perpendicular to the direction of thickness D of core 730, and are formed outside the outer shape of core 730. Furthermore, protrusions 713 are provided on pressing surfaces 711. The protrusions 713 are oriented in a direction perpendicular to the facing direction of magnetic gap M.

[0041] The pair of pressing surfaces 711 shown in this modification press down on core 730 via first mold section 710 when second mold section 720 is molded, thereby enabling accurate adjustment of dimensional variations in magnetic gap M and accurate positioning of magnetic gap M relative to second mold section 720. Furthermore, the anchor effect of convex sections 713 between first mold section 710 and second mold section 720 ensures a strong fixation, making this suitable as a core member for vehicles that require durability and reliability.

[0042] Although the protrusions 713 have been described as being provided in a direction perpendicular to the facing direction of the magnetic gap M, they may also be provided in the same direction as the facing direction of the magnetic gap M. They may also be provided in a direction perpendicular to the facing direction and in the same direction as the facing direction, i.e., in a cross shape. In addition to the protrusions 713, they may also be recesses that are provided in at least one direction perpendicular to the facing direction of the magnetic gap M or in the same direction as the facing direction of the magnetic gap M. Furthermore, recesses and protrusions may be provided in combination.

[0043] According to the embodiment described above, the following effects can be obtained. (1) Core member 750 of the current detector includes an annular core 730 having a magnetic gap M, a first molded portion 710 that seals a portion of core 730, and a second molded portion 720 that seals first molded portion 710. First molded portion 710 has a pair of pressing surfaces 711 that sandwich magnetic gap M, and the pair of pressing surfaces 711 are sealed by second molded portion 720. This provides a highly reliable current detector that exhibits high accuracy and vibration resistance in core mounting. Furthermore, by integrally sealing core 730, first molded portion 710, and second molded portion 720, the current detector can be made smaller.

[0044] The present invention is not limited to the above-described embodiments, and other forms that can be conceived within the scope of the technical concept of the present invention are also included within the scope of the present invention as long as they do not impair the characteristics of the present invention. Furthermore, configurations that combine the above-described embodiments with modified examples may also be used. [Explanation of symbols]

[0045] 100···Power conversion device, 200···Battery, 300···Motor, 400···Vehicle control device, 500···Capacitor, 600···Inverter, 700···Current detector, 710···First molded part, 711···Pressing surface, 712···Recess, 720···Second molded part, 722···Board mounting surface, 723···Pressing part, 724···Groove part, 730···Core, 740···Electromagnetic conversion element, 750···Core member, 760···Circuit board, 800···Control part, M···Magnetic gap, N···Magnetic flux saturation part, Bu, Bv, Bw···AC bus bar.

Claims

1. a ring-shaped core having a magnetic gap; a pair of first molded parts each sealing a part of the core with the magnetic gap therebetween; and a second molded part sealing the first molded part; The pair of first mold parts each have a substantially rectangular parallelepiped shape, At least one surface of each of the pair of first molded parts forms a pair of pressing surfaces sandwiching the magnetic gap, the pair of pressing surfaces are sealed by the second mold portion, The core and the first molded portion are core members of the current detector that protrude from an end face of the second molded portion.

2. 2. The core member of the current detector according to claim 1, The pair of pressing surfaces of the first molded portion are a core member of the current detector, a part of which is exposed from the second molded portion.

3. 2. The core member of the current detector according to claim 1, The core member of the current detector has at least one of a recess and a protrusion formed on the pair of pressing surfaces of the first molded portion.

4. 2. The core member of the current detector according to claim 1, The second molded portion is a core member of the current detector having a pressing portion that presses a part of the pressing surface of the first molded portion.

5. 5. The core member of the current detector according to claim 4, The pair of pressing surfaces are outer surfaces of the pair of first molded portions on the opposite side to the magnetic gap side, and are core members of the current detector formed outside the outer shape of the core.

6. 2. The core member of the current detector according to claim 1, The core and the first molded portion are core members of the current detector that protrude from the lower end surface of the second molded portion.

7. The core member of the current detector according to any one of claims 1 to 6, The core is a core member of the current detector, which is a wound core formed by winding a magnetic strip in a spiral shape.

8. The core member of the current detector according to any one of claims 1 to 6, a plurality of the cores sealed by the first mold portion; The second molded portion is a core member of the current detector that seals the first molded portion so as to connect the plurality of cores sealed by the first molded portion.

9. A core member of a current detector according to any one of claims 1 to 6; an electromagnetic transducer disposed within the magnetic gap; a circuit board on which the electromagnetic transducer is mounted.

10. 10. The current detector according to claim 9, the second molded portion has a substrate mounting surface on which the circuit substrate is mounted, and a groove portion recessed from the substrate mounting surface toward the magnetic gap, The electromagnetic conversion element is housed in the groove of the second molded part.

11. a current detector according to claim 9; an inverter that converts DC power into AC power and vice versa; a bus bar that transmits the DC power or the AC power and is inserted into the core.

Images