Current sensor and electric power conversion apparatus

Abstract

To suppress high-temperature anomalies and improve detection accuracy in coreless current sensors.SOLUTION: A current sensor detects the current in a conductor 1 of an electric power conversion apparatus. A storage member 2 covers a portion of the outer circumference between one end and the other end of the conductor 1. A first opening 2a is formed in the storage member 2 such that one surface of the conductor 1 is exposed. A detection unit 5 for detecting the current in the conductor 1 is mounted on a substrate 4. The substrate 4 with the detection unit 5 mounted thereon is positioned within the first opening 2a. A thermal insulation material 3 is positioned within the first opening 2a and between the detection unit 5 and the conductor 1.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a technology for heat management (heat dissipation, insulation) of a current sensor, and more particularly to a technology for protecting components of a current sensor from heat generation of a conductor. [Background technology]

[0002] An inverter is a power conversion device that converts DC power into AC power and supplies the power to a load such as a motor.

[0003] Conventionally, core-equipped HCT (Hall Current Detector) modules have been the main method for measuring inverter output current. The output conductor and HCT module are typically separate and are combined during assembly. Furthermore, HCT modules often have a resin case housing a board with a core and sensor IC mounted on it.

[0004] In particular, the operating environment (operating temperature) of the current sensor is limited by the electronic components, including the sensor IC. Although the electronic components generate heat themselves, the effect is small; most of the heat is due to heat transfer from the core and conductors.

[0005] Therefore, the existing heat countermeasure is to dissipate heat to the inverter housing (case) via a thermal interface material (TIM) such as a thermally conductive sheet on the resin case or conductor. Figure 1 shows an example of this current sensor structure. In this structure, a core 10 and a sensor IC (not shown) are provided on each of the three-phase conductors 1, and are integrated into a resin case 11.

[0006] In recent years, coreless current sensors that do not use a core for magnetic flux collection have begun to appear as a method of current detection. Patent Document 1 discloses prior art for this configuration. Coreless current sensors can be made smaller because they do not use a core, which previously occupied most of the volume of the current sensor. However, this has the drawback of requiring the sensor and conductor to be placed closer together than ever before to prevent magnetic flux collection and crosstalk. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Patent Publication No. 2021-162416 [Non-patent literature]

[0008] [Non-Patent Document 1] F.C.C. Co., Ltd., Technology and Development, Papermaking and New Material Technology, [online, searched February 14, 2024], Internet<URL https: / / www.fcc-net.co.jp / tech / papermaking / > Summary of the Invention [Problem to be solved by the invention]

[0009] In order to achieve a smaller inverter (higher power density), the downsizing and heat generation of individual components become issues.

[0010] In many of the current sensors with cores that have been available in the past, the sensor part (board) is covered with a resin case, and is not configured to be directly subjected to the heat from the conductor 1.

[0011] On the other hand, as mentioned above, the coreless current sensor is configured so that the sensor and the conductor 1 are placed in close proximity, and therefore the sensor is directly affected by the heat of the conductor 1, which causes problems with the heat resistance temperature of the sensor.

[0012] On the other hand, if the distance between the conductor 1 and the sensor is increased, the detection accuracy and the influence of crosstalk (influence from other phases, etc.) will increase.

[0013] For the reasons described above, the challenge for coreless current sensors is to suppress high temperature abnormalities and improve detection accuracy. [Means for solving the problem]

[0014] The present invention was devised in view of the above-mentioned problems of the conventional art, and one aspect of the present invention is a current sensor for detecting the current of a conductor of a power conversion device, characterized by comprising: a housing member that covers a part of the outer periphery between one end and the other end of the conductor and has a first open portion formed so that one side of the conductor is exposed; a substrate that is arranged within the first open portion and on which a detection unit that detects the current of the conductor is mounted; and an insulating material that is arranged within the first open portion and between the detection unit and the conductor.

[0015] In another aspect, a current sensor for detecting a current in a conductor of a power conversion device includes a housing member that covers a portion of the outer periphery between one end and the other end of the conductor, and has a first opening formed to expose one side of the conductor and a second opening formed to expose the other side of the conductor; a substrate that is arranged within the first opening and has a detection unit that detects the current in the conductor mounted thereon; and a thermally conductive material that is arranged within the second opening, wherein the conductor comes into contact with the housing of the power conversion device via the thermally conductive material.

[0016] In one embodiment, the storage member has a second open portion formed so that the other side of the conductor is exposed, and is provided with a thermally conductive material arranged within the second open portion, and the conductor comes into contact with the housing of the power conversion device via the thermally conductive material.

[0017] In one embodiment, the storage member is characterized in that it covers a portion of the outer periphery between one end and the other end of the plurality of conductors, and the first opening portion is formed so that one side of the plurality of conductors is exposed.

[0018] The present invention is also characterized by a power conversion device including the current sensor. [Effects of the Invention]

[0019] According to the present invention, it is possible to suppress high temperature abnormalities and improve detection accuracy in a coreless current sensor. [Brief explanation of the drawings]

[0020] [Figure 1] FIG. 10 is a schematic diagram showing the configuration of a conventional current sensor with a core. [Figure 2] FIG. 1 is a circuit diagram showing the configuration of a power conversion device (inverter). [Figure 3] FIG. 1 is a schematic diagram showing the configuration of a current sensor according to a first embodiment. [Figure 4] FIG. 6 is a schematic diagram showing the configuration of a current sensor according to a second embodiment. [Figure 5] FIG. 10 is a schematic diagram showing the configuration of a current sensor according to a third embodiment. [Figure 6] FIG. 10 is a schematic diagram showing the configuration of a current sensor according to a fourth embodiment. [Figure 7] FIG. 10 is a schematic diagram showing the configuration of a current sensor according to a fifth embodiment. [Figure 8] FIG. 13 is a schematic diagram showing the configuration of a current sensor according to a sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0021] First to sixth embodiments of the current sensor of the present invention will be described in detail below with reference to FIGS.

[0022] [Embodiment 1] First, a typical power conversion device (for example, an inverter, hereinafter referred to as an inverter) will be described based on the electrical circuit diagram of Fig. 2. As shown in Fig. 2, a capacitor (for example, a film capacitor) C is connected between the P terminal and the N terminal. Furthermore, switching elements Su, Sx, switching elements Sv, Sy, and switching elements Sw, Sz are connected in series between the P terminal and the N terminal. The switching elements are, for example, IGBTs, and the switching elements Su to Sz constitute a power semiconductor (IGBT package) 12.

[0023] A motor M is connected to the AC side of the power semiconductor 12 (the connection point of the switching elements Su and Sx, the connection point of the switching elements Sv and Sy, and the connection point of the switching elements Sw and Sz). A current sensor 13 is provided between the power semiconductor 12 and the motor M.

[0024] Capacitor C serves to smooth the DC link voltage. A discharge resistor R is connected in parallel to capacitor C. Discharge resistor R is provided to discharge the charge in capacitor C when the inverter input power is turned off, thereby preventing electric shock accidents.

[0025] 3A and 3B are schematic diagrams showing the configuration of the current sensor of the present embodiment 1. Fig. 3A is an exploded view, Fig. 3B is an assembly view, and Fig. 3C is an AA cross-sectional view.

[0026] As shown in FIG. 3, a housing member 2 for housing a detection unit 5 and a substrate 4 (described later) is integrally molded with a flat conductor (bus bar) 1 of the inverter. The housing member 2 is made of, for example, resin. The housing member 2 is formed in a roughly rectangular parallelepiped shape and encloses a portion of the outer periphery of the conductor 1 between one end and the other end. In other words, the housing member 2 is integrally molded so that the conductor 1 passes through it. In addition, the housing member 2 is formed with a first opening 2a that is rectangular and opens so that one side of the conductor 1 is exposed.

[0027] A detection unit (sensor IC) 5 that detects the current of the conductor 1 is mounted on the substrate 4. The substrate 4 on which the detection unit 5 is mounted is provided in the first open portion 2a of the storage member 2. Here, the substrate 4 is installed so that the surface on which the detection unit 5 is mounted faces the conductor 1. The heat insulating material 3 is disposed in the first open portion 2a of the storage member 2, and between the detection unit 5 and the conductor 1.

[0028] In the first embodiment, a heat insulating material 3 is sandwiched between a substrate 4 on which a detection unit 5 is mounted and a conductor 1. By sandwiching the heat insulating material 3, even if the conductor 1 generates heat, the heat is not transmitted to the detection unit 5.

[0029] For example, a paper material is used for the heat insulating material 3. As described in Non-Patent Document 1, heat insulation and insulation can be achieved by the pore structure unique to paper. Also, materials that are combined with various materials such as functional fibers and natural materials using papermaking technology may be used.

[0030] The substrate 4 on which the detection unit 5 is mounted is provided with a connector (not shown), and the current detection value is transmitted to the control substrate of the inverter via a cable connected to the connector.

[0031] As described above, according to the first embodiment, the use of a coreless current sensor makes it possible to reduce the size of the current sensor.

[0032] Furthermore, by placing the substrate 4 inside the housing member 2 and further mounting the detection unit 5 on the surface of the substrate 4 facing the conductor 1, the detection unit 5 and the conductor 1 are placed in close proximity to each other, which makes it possible to improve detection accuracy and suppress the effects of crosstalk.

[0033] Furthermore, by sandwiching the heat insulating material 3 between the detection unit 5 and the conductor 1, it is possible to obtain the effect (heat insulating effect) of suppressing heat transfer from the heat generated by the conductor 1 (radiant heat) to the detection unit 5. As a result, it is possible to suppress abnormally high temperatures in the detection unit 5.

[0034] [Embodiment 2] Fig. 4 is a schematic diagram showing the configuration of the current sensor of the second embodiment. Fig. 4(a) is an exploded view, Fig. 4(b) is an assembly view, and Fig. 4(c) is an AA cross-sectional view. The same parts as in Fig. 3 are given the same reference numerals, and their explanation will be omitted.

[0035] 4, in the second embodiment, the heat insulating material 3 is omitted. Instead, the housing member 2 is formed with a rectangular second opening 2b so that the other surface of the conductor 1 (the surface opposite the detection unit 5 and the substrate 4) is exposed. A TIM material (thermal conductive material) 6 such as a thermally conductive sheet is placed in the exposed portion of the conductor 1 in the second opening 2b, and the conductor 1 is brought into contact with a housing (case) 7 of the inverter via the TIM material 6.

[0036] As described above, according to the second embodiment, the same effects as those of the first embodiment can be achieved. In addition, by dissipating the heat of the conductor 1 to the inverter housing 7 via the TIM material 6, it is possible to reduce the heat transfer to the detection unit 5. As a result, it is possible to suppress abnormally high temperatures in the detection unit 5.

[0037] [Embodiment 3] Fig. 5 is a schematic diagram showing the configuration of the current sensor of the third embodiment. Fig. 5(a) is an exploded view, Fig. 5(b) is an assembly view, and Fig. 5(c) is an AA cross-sectional view. The same parts as those in Fig. 3 and Fig. 4 are given the same reference numerals, and their explanation will be omitted.

[0038] The third embodiment is a combination of the first and second embodiments. A first open section 2a and a second open section 2b are formed in the housing member 2. A substrate 4 on which a detection unit 5 is mounted is provided in the first open section 2a of the housing member 2. A heat insulating material 3 is installed in the first open section 2a of the housing member 2, and between the detection unit 5 and the conductor 1. Furthermore, a TIM material 6 is installed in the second open section 2b of the housing member 2, and the conductor 1 is brought into contact with a housing (case) 7 of the inverter via the TIM material 6.

[0039] As described above, according to the third embodiment, the same effects as those of the first and second embodiments are achieved. In addition, the surface of the conductor 1 facing the detection unit 5 is insulated, and the opposite surface dissipates heat to the housing (case) 7 via the TIM material 6, thereby further reducing heat transfer from the conductor 1 to the detection unit 5. As a result, abnormally high temperatures in the detection unit 5 can be suppressed.

[0040] [Embodiment 4] Fig. 6 is a schematic diagram showing the configuration of a current sensor according to the fourth embodiment. The fourth embodiment is a three-phase version of the first embodiment. Fig. 6(a) shows the case where the configuration of the first embodiment is applied to each phase, Fig. 6(b) shows the case where the configuration is applied to all three phases, and Fig. 6(c) is a cross-sectional view taken along the line AA in Fig. 6(b). The same parts as in Fig. 1 are designated by the same reference numerals, and their description will be omitted.

[0041] In the case of a single-phase inverter or a three-phase inverter, multiple conductors 1 (two for a single-phase inverter, three for a three-phase inverter) are often arranged close to each other. In this case, the detector 5 provided on the conductor 1 of one phase is susceptible to crosstalk (influence of magnetic fields) from the other phases.

[0042] In addition to applying the first embodiment to each phase as shown in Fig. 6(a), it may also be configured as a three-phase (or single-phase) unit as shown in Fig. 6(b). In this case, the housing member 2 encloses a portion of the outer periphery between one end and the other end of the multiple (three-phase) conductors 1. The housing member 2 has a first opening 2a that is rectangularly opened so that one side of the multiple (three-phase) conductors 1 is exposed.

[0043] Then, a board 4 on which three detectors 5 corresponding to the three phases are mounted is provided within the first open portion 2a. A heat insulating material 3 is arranged within the first open portion 2a of the storage member 2, and between each detector 5 and each conductor 1. In FIG. 6, one board 4 is provided for the three phases, but separate boards for the three phases may also be used. Also, a heat insulating material 3 is provided for each phase, but it may be large enough to cover the conductors 1 for the three phases, and one piece of heat insulating material 3 may be used for the three phases.

[0044] In addition, in the majority of three-phase inverters, the total value of the three-phase currents is 0. In this case, for example, the V-phase current can be calculated as V-phase current = -(U-phase current + W-phase current). Therefore, it is not necessary to implement a detector 5 for one of the three phases.

[0045] As described above, according to this embodiment 4, even when multiple conductors 1 are arranged closely together, such as in a single-phase inverter or a three-phase inverter, the same effects as those of the embodiment 1 can be achieved, and noise can be suppressed and a decrease in detection accuracy due to crosstalk can be prevented.

[0046] [Embodiment 5] Fig. 7 is a schematic diagram showing the configuration of a current sensor according to the fifth embodiment. In this fifth embodiment, the second embodiment is configured to be three-phase like the fourth embodiment. Fig. 7(a) shows the case where the configuration of the second embodiment is applied to each phase, Fig. 7(b) shows the case where the three phases are collectively configured, and Fig. 7(c) is a cross-sectional view taken along the line AA in Fig. 7(b). The same parts as those in Figs. 4 and 6 are designated by the same reference numerals, and their description will be omitted.

[0047] In addition to applying the second embodiment to each phase as shown in FIG. 7(a), it may also be configured as a three-phase (or single-phase) unit as shown in FIG. 7(b). In this case, the housing member 2 encloses a portion of the outer periphery between one end and the other end of the multiple (three-phase) conductors 1, and a first open portion 2a is formed as in the fourth embodiment. In the fifth embodiment, the heat insulating material 3 is omitted as in the second embodiment. In addition, the housing member 2 is formed with a second open portion 2b that is rectangularly opened so that the other faces of the multiple (three-phase) conductors 1 are exposed.

[0048] Then, a TIM material 6 is placed in the area where the conductor 1 is exposed in the second open portion 2b, and a housing (case) 7 is brought into contact with the conductor 1 via the TIM material 6. Here, a total of three TIM materials 6 are provided, one for each conductor 1, but one TIM material 6 may be provided for three conductors 1.

[0049] In addition, in the majority of three-phase inverters, the total value of the three-phase currents is 0. In this case, for example, the V-phase current can be calculated as V-phase current = -(U-phase current + W-phase current). Therefore, it is not necessary to mount the detector 5 and TIM material 6 for one of the three phases.

[0050] As described above, according to the fifth embodiment, the same effects as those of the second and fourth embodiments can be obtained.

[0051] [Embodiment 6] Fig. 8 is a schematic diagram showing the configuration of a current sensor according to the sixth embodiment. In this sixth embodiment, the third embodiment is configured as a three-phase sensor, similar to the fourth and fifth embodiments. Fig. 8(a) shows the case where the configuration of the third embodiment is applied to each phase, Fig. 8(b) shows the case where the three phases are collectively configured, and Fig. 8(c) is a cross-sectional view taken along the line AA in Fig. 8(b). The same parts as those in Figs. 4, 6, and 7 are designated by the same reference numerals, and their description will be omitted.

[0052] In addition to applying the third embodiment to each phase as shown in Fig. 8(a), it may also be configured as a three-phase (or single-phase) unit as shown in Fig. 8(b). In this case, the housing member 2 encloses a part of the outer periphery between one end and the other end of the three-phase conductor 1, and first and second openings 2a, 2b are formed as in the fifth embodiment.

[0053] Then, a substrate 4 on which three detectors 5 are mounted is provided in the first open portion 2a. A heat insulating material 3 is placed in the first open portion 2a and between each detector 5 and each conductor 1. A TIM material 6 is placed in the second open portion 2b at a location where the conductor 1 is exposed, and a housing (case) 7 is brought into contact with the conductor 1 via the TIM material 6.

[0054] As described above, according to the sixth embodiment, the same effects as those of the third, fourth and fifth embodiments can be obtained.

[0055] Although the present invention has been described in detail above only with respect to the specific examples, it will be apparent to those skilled in the art that various modifications and variations are possible within the scope of the technical concept of the present invention, and it is natural that such modifications and variations fall within the scope of the claims.

[0056] The current sensors of the first to sixth embodiments are applicable to power conversion devices in general other than inverters, and are applicable not only to AC current detection sensors as shown in FIG. [Explanation of symbols]

[0057] 1...conductor 2...Storage components 2a, 2b...1st, 2nd open part 3...Insulation material 4...Substrate 5...Detection unit (sensor IC) 6...TIM material (thermal conductive material) 7...Case 10...Core 11...Resin case 12...Power semiconductor (IGBT package) 13...Current sensor

Claims

1. A current sensor for detecting a current in a conductor of a power conversion device, a housing member that encloses a portion of the outer periphery of the conductor between one end and the other end and has a first opening formed therein so that one surface of the conductor is exposed; a substrate on which a detection unit for detecting a current in the conductor is mounted, the detection unit being disposed in the first open portion; a heat insulating material disposed in the first open portion and between the detection portion and the conductor; A current sensor comprising:

2. A current sensor for detecting a current in a conductor of a power conversion device, a housing member that encloses a portion of the outer periphery of the conductor between one end and the other end, and has a first opening formed so that one surface of the conductor is exposed, and a second opening formed so that the other surface of the conductor is exposed; a substrate on which a detection unit for detecting a current in the conductor is mounted, the detection unit being disposed in the first opening; a thermally conductive material disposed within the second opening; Equipped with The current sensor is characterized in that the conductor is in contact with the housing of the power conversion device via the thermally conductive material.

3. The housing member has a second opening formed therein so that the other surface of the conductor is exposed, a thermally conductive material disposed within the second open portion; 2. The current sensor according to claim 1, wherein the conductor is in contact with the housing of the power converter via the thermally conductive material.

4. 3. The current sensor according to claim 1, wherein the housing member covers a portion of the outer periphery between one end and the other end of the plurality of conductors, and the first opening portion is formed so that one side of the plurality of conductors is exposed.

5. A power conversion device comprising the current sensor according to claim 1 or 2.

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