Common mode noise filter

Abstract

To provide a common mode noise filter that is used for a motor driving system.SOLUTION: A common mode noise filter that comprises an annular core formed of a magnetic material that is configured such that a DC wiring group connecting a battery and an inverter to each other and an AC wiring group connecting the inverter and a motor to each other pass through the inside of a ring, wherein the inside of the ring is divided by a partition part. One side of the inside of the ring of the annular core divided by the partition part is configured such that the DC wiring group passes therethrough. The other side of the inside of the ring of the annular core divided by the partition part is configured such that the AC wiring group passes therethrough. The direction in which the DC wiring group passes through the inside of the ring of the annular core from the battery toward the inverter, and the direction in which the AC wiring group passes through the inside of the ring of the annular core from the inverter toward the motor, are the same direction relative to the annular core.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The technology disclosed in this specification relates to a common mode noise filter used in a motor drive system. [Background technology]

[0002] The motor drive system includes a battery, an inverter that converts DC power supplied from the battery into AC power and outputs it, and a motor driven by the AC power output from the inverter. The battery and the inverter are connected by a pair of DC wiring groups (P wiring and N wiring). The inverter and the motor are connected by three AC wiring groups (U-phase wiring, V-phase wiring, and W-phase wiring). Patent Document 1 discloses a common mode noise filter that includes an annular core made of a magnetic material and is configured so that the DC wiring groups pass through the inside of the ring in order to attenuate common mode noise flowing through the motor drive system. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2020-519222 Summary of the Invention [Problem to be solved by the invention]

[0004] Common mode noise flowing through a motor drive system flows through both the DC wiring group and the AC wiring group at the same time. Therefore, in order to effectively attenuate the common mode noise flowing through a motor drive system, it is desirable to take measures against the common mode noise flowing through both the DC wiring group and the AC wiring group. The common mode noise filter in Patent Document 1 is provided only on the DC wiring group, and is insufficient as a common mode noise countermeasure. This specification provides a common mode noise filter that is useful for the common mode noise flowing through a motor drive system. [Means for solving the problem]

[0005] The present specification can provide a common mode noise filter for use in a motor drive system. The common mode noise filter may include an annular core made of a magnetic material, configured so that a DC wiring group connecting a battery and an inverter and an AC wiring group connecting the inverter and a motor pass through the inside of the ring, the inside of the ring being divided by a partition. One side of the inside of the ring of the annular core divided by the partition may be configured so that the DC wiring group passes through. The other side of the inside of the ring of the annular core divided by the partition may be configured so that the AC wiring group passes through. The direction in which the DC wiring group passes through the inside of the ring of the annular core from the battery to the inverter and the direction in which the AC wiring group passes through the inside of the ring of the annular core from the inverter to the motor may be the same with respect to the annular core.

[0006] In the above common mode noise filter, when common mode noise flows through the motor drive system, the magnetic flux generated in the annular core by the common mode noise flowing through the DC wiring group and the magnetic flux generated in the annular core by the common mode noise flowing through the AC wiring group are oriented in the same direction, resulting in a mutually strengthening relationship. Therefore, the above common mode noise filter has high inductance with respect to the common mode noise flowing through the motor drive system, and can exhibit a high filtering effect against the common mode noise. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a diagram illustrating a schematic configuration of a motor drive system. [Diagram 2] 1 is a schematic cross-sectional view of a common mode noise filter in a state in which a DC wiring group and an AC wiring group pass through the common mode noise filter; [Diagram 3]1A is a diagram for explaining magnetic flux generated in an annular core of a common mode noise filter when common mode noise flows in a first direction through a DC wiring group and an AC wiring group, and FIG. 1B is a diagram for explaining magnetic flux generated in an annular core of a common mode noise filter when common mode noise flows in a second direction opposite to the first direction through a DC wiring group and an AC wiring group. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] As shown in Fig. 1, the motor drive system 1 includes a battery 2 which is a high-voltage DC power source, a three-phase inverter 4 which converts DC power supplied from the battery 2 into AC power and outputs the AC power, and a three-phase AC motor 6 which is driven by the AC power output from the three-phase inverter 4. Note that a smoothing capacitor, a DC / DC converter, etc. may be provided between the battery 2 and the three-phase inverter 4 as necessary. Such a motor drive system 1 may be mounted on, for example, an electric vehicle, although it is not particularly limited thereto. Note that the "electric vehicle" in this specification includes a battery electric vehicle (BEV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a fuel cell electric vehicle (FCEV), etc.

[0009] The battery 2 and the three-phase inverter 4 are connected by a pair of DC wiring groups (i.e., P wiring 10P and N wiring 10N). The P wiring 10P connects the positive electrode of the battery 2 and the high-voltage terminal of the three-phase inverter 4, and the N wiring 10N connects the negative electrode of the battery 2 and the low-voltage terminal of the three-phase inverter 4. Each of the DC wiring groups 10P and 10N is configured by a bus bar. The three-phase inverter 4 and the three-phase AC motor 6 are connected by three AC wiring groups (i.e., U-phase wiring 10U, V-phase wiring 10V, and W-phase wiring 10W). One end of each of the U-phase wiring 10U, V-phase wiring 10V, and W-phase wiring 10W is connected to the midpoint of the corresponding phase of the three-phase inverter 4, and the other end is connected to the neutral point of the three-phase AC motor 6. Each of the AC wiring groups 10U, 10V, and 10W is configured by a bus bar.

[0010] 2 shows the common mode noise filter 20 used in the motor drive system 1. The common mode noise filter 20 has an annular core made of a magnetic material, and is configured so that the DC wiring groups 10P, 10N and the AC wiring groups 10U, 10V, 10W pass through the inside of the ring.

[0011] The annular core of the common mode noise filter 20 has a first U-shaped core portion 22, a second U-shaped core portion 24, a first block core portion 26, a second block core portion 28, and a partition portion 29. The U-shaped core portions 22, 24 and the block core portions 26, 28 form a rectangular parallelepiped outer shape with both ends open.

[0012] Each of the first U-shaped core portion 22 and the second U-shaped core portion 24 has a substantially U-shaped shape when viewed in a cross section perpendicular to the axial direction of the annular core (in this example, the direction perpendicular to the paper surface). A first block core portion 26 is interposed between one end of each of the first U-shaped core portion 22 and the second U-shaped core portion 24, and one end of each of the first U-shaped core portion 22 and the second U-shaped core portion 24 is joined via the first block core portion 26. A second block core portion 28 is interposed between the other end of each of the first U-shaped core portion 22 and the second U-shaped core portion 24, and the other end of each of the first U-shaped core portion 22 and the second U-shaped core portion 24 is joined via the second block core portion 28. The U-shaped core portions 22, 24 and the block core portions 26, 28 may be made of the same type of magnetic material. The partition portion 29 extends inside the ring of the annular core along the axial direction of the annular core, and when viewed in a cross section perpendicular to the axial direction of the annular core, one side surface of the partition portion 29 is joined to the first block core portion 26 and the other side surface of the partition portion 29 is joined to the second block core portion 28. In this manner, when viewed in a cross section perpendicular to the axial direction of the annular core, the partition portion 29 divides the ring inside of the annular core into two. The partition portion 29 may be made of a different type of magnetic material from the U-shaped core portions 22, 24 and the block core portions 26, 28, as described later.

[0013] The DC wiring groups 10P and 10N pass through one side of the ring of the annular core of the common mode noise filter 20 divided by the partition 29, i.e., the internal space surrounded by the first U-shaped core portion 22 and the partition portion 29. In this example, the DC wiring groups 10P and 10N pass through the ring of the annular core so that the direction from the battery 2 to the three-phase inverter 4 is the depth of the paper. The AC wiring groups 10U, 10, and 10W pass through the other side of the ring of the annular core of the common mode noise filter 20 divided by the partition portion 29, i.e., the internal space surrounded by the second U-shaped core portion 24 and the partition portion 29. In this example, the AC wiring groups 10U, 10, and 10W pass through the ring of the annular core so that the direction from the three-phase inverter 4 to the three-phase AC motor 6 is the depth of the paper. In this way, the direction in which the DC wiring groups 10P, 10N pass through the annular core from the battery 2 toward the three-phase inverter 4 (in this example, toward the depth of the paper) and the direction in which the AC wiring groups 10U, 10, 10W pass through the annular core from the three-phase inverter 4 toward the three-phase AC motor 6 (in this example, toward the depth of the paper) are the same relative to the annular core.

[0014] Fig. 3(A) shows the magnetic flux generated in the annular core of the common mode noise filter 20 when common mode noise flows from the battery 2 to the three-phase AC motor 6. Fig. 3(B) shows the magnetic flux generated in the annular core of the common mode noise filter 20 when common mode noise flows from the three-phase AC motor 6 to the battery 2. The solid lines indicate the magnetic flux generated in the annular core by the common mode noise flowing through the DC wiring groups 10P, 10N, and the dashed lines indicate the magnetic flux generated in the annular core by the common mode noise flowing through the AC wiring groups 10U, 10V, 10W.

[0015] 3(A) and 3(B), the magnetic flux generated in the U-shaped core portions 22, 24 and the block core portions 26, 28 has a mutually reinforcing relationship in which the magnetic flux generated by the common mode noise flowing through the DC wiring groups 10P, 10N and the magnetic flux generated by the common mode noise flowing through the AC wiring groups 10U, 10V, 10W have the same direction (clockwise in the example of FIG. 3(A) and counterclockwise in the example of FIG. 3(B)). Therefore, the common mode noise filter 20 has a high inductance with respect to the common mode noise flowing through the motor drive system 1, and can exhibit a high filtering effect against the common mode noise.

[0016] 3(A) and 3(B), the magnetic flux generated in the partition portion 29 is oriented in the opposite direction to the magnetic flux generated by the common mode noise flowing through the DC wiring groups 10P, 10N and the magnetic flux generated by the common mode noise flowing through the AC wiring groups 10U, 10V, 10W, and the magnetic fluxes weaken each other. Therefore, the magnetic material of the partition portion 29 can be made of a material that has lower magnetic properties and is less expensive than the magnetic materials of the U-shaped core portions 22, 24 and the block core portions 26, 28. This makes it possible to keep the manufacturing cost of the common mode noise filter 20 low.

[0017] Here, as a comparative example, consider providing a common mode noise filter with an annular core, which is an independent magnetic component, to each of the DC wiring groups 10P, 10N and the AC wiring groups 10U, 10V, 10W. In this case, two common mode noise filters are required, which raises concerns about an increase in the number of components, weight, total size, and manufacturing cost. On the other hand, the common mode noise filter 20 of this embodiment is configured as a single magnetic component, which can solve such problems. In addition, in the common mode noise filter 20 of this embodiment, the magnetic flux is superimposed as described above, and it is expected to exhibit a higher filtering effect than the comparative example. [Explanation of symbols]

[0018] 1: motor drive system, 2: battery, 4: three-phase inverter, 6: three-phase AC motor, 10N: N-phase wiring, 10P: P-phase wiring, 10U: U-phase wiring, 10V: V-phase wiring, 10W: W-phase wiring, 20: common mode noise filter, 22: first U-shaped core portion, 24: second U-shaped core portion, 26: first block core portion, 28: second block core portion, 29: partition portion

Claims

[Claim 1] A common mode noise filter for use in a motor drive system, comprising: a ring-shaped core made of a magnetic material, the ring-shaped core being configured such that a DC wiring group connecting a battery and an inverter and an AC wiring group connecting the inverter and a motor pass through the inside of the ring, the inside of the ring being divided by a partition portion; the DC wiring group passes through one side of the inside of the ring of the annular core divided by the partition portion, the other side of the inside of the ring of the annular core divided by the partition portion is configured so that the AC wiring group passes through; a direction in which the group of DC wirings passes through the inside of the ring of the annular core from the battery toward the inverter, and a direction in which the group of AC wirings passes through the inside of the ring of the annular core from the inverter toward the motor, the direction being the same with respect to the annular core.

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