Power converter

Abstract

A power conversion device (100) comprises: a capacitor element (12); switching elements (20), (21); a wiring member (30); a cooling body (3); and a heat-conductive insulating member (5). The wiring member (30) is connected to the capacitor element (12) and the switching elements (20), (21). The capacitor element (12) and the switching elements (20), (21) are mounted on the cooling body (3). The heat-conductive insulating member (5) is connected to the cooling body (3) and the wiring member (30). The wiring member (30) has a first contact portion (5a) and a second contact portion (5b). The wiring member (30) is connected to the capacitor element (12) at the first contact portion (5a), and connected to the switching elements (20), (21) at the second contact portion (5b). The heat resistance of the wiring member (30) from the first contact portion (5a) to the heat-conductive insulating member (5) is less than the heat resistance of the wiring member (30) from the second contact portion (5b) to the heat-conductive insulating member (5).

Description

Technical Field

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

Background Art

[0002] In recent years, power conversion devices such as voltage type inverters that convert DC power into AC power have been used not only in air conditioners, machine tools, railway drive devices, and elevators, but also in power conditioners for renewable energy and electric vehicles. As a configuration of such a power conversion device, there is known one having a cooler equipped with a capacitor element and a switching element, a wiring member connected to the capacitor element and the switching element, and a thermally conductive insulating member connected to the wiring member and the cooler (see, for example, Japanese Patent Application Laid-Open No. 2017-188998).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, since the power conversion device as described above is applied to a wide range of products, electric power miniaturization of the conversion device is required. In particular, miniaturization of the capacitor element, which occupies a high proportion of the volume inside the power conversion device, is required, and improvement of the cooling performance of the capacitor element is an issue for achieving such miniaturization.

[0005] The present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a power conversion device with improved cooling performance of a capacitor element.

Means for Solving the Problems

[0006] A power conversion device according to this disclosure comprises a capacitor element, a switching element, a wiring member, a cooling body, and a thermally conductive insulating member. The wiring member is electrically connected to the capacitor element and the switching element. The cooling body mounts the capacitor element and the switching element. Department The material is connected to a cooling element and a wiring member. The wiring member has a first contact portion and a second contact portion. The wiring member is connected to a capacitor element at the first contact portion. The wiring member is connected to a switching element at the second contact portion. The thermal resistance of the wiring member in the region from the first contact portion to the thermally conductive insulating member is smaller than the thermal resistance of the wiring member in the region from the second contact portion to the thermally conductive insulating member. [Effects of the Invention]

[0007] According to the above, a power conversion device with improved cooling performance of the capacitor element can be obtained. [Brief explanation of the drawing]

[0008] [Figure 1] This is a circuit diagram of a power conversion device according to Embodiment 1. [Figure 2] This is a perspective view of the power conversion device according to Embodiment 1. [Figure 3] This is a plan view of the power conversion device according to Embodiment 1. [Figure 4] This is a cross-sectional view of the line segment IV-IV in Figure 3. [Figure 5] Figure 3 is a cross-sectional view of the line segment VV. [Figure 6] This is a plan view showing a modified example of the power conversion device according to Embodiment 1. [Figure 7] This is a circuit diagram of the power conversion device according to Embodiment 2. [Figure 8] This is a perspective view of the power conversion device according to Embodiment 2. [Figure 9] This is a plan view of the power conversion device according to Embodiment 2. [Figure 10] Figure 9 shows a cross-sectional view of line segment XX. [Figure 11] Figure 9 shows a cross-sectional view of the line segment XI-XI. [Figure 12] This is a cross-sectional view of a power conversion device according to Embodiment 3. [Figure 13] This is a cross-sectional view of a power conversion device according to Embodiment 3. [Figure 14] This is a cross-sectional view of a power conversion device according to Embodiment 4. [Figure 15] This is a cross-sectional view of a power conversion device according to Embodiment 4. [Modes for carrying out the invention]

[0009] Embodiments of the present disclosure will be described below. Unless otherwise specified, the same or corresponding parts in the following drawings will be given the same reference numerals, and their descriptions will not be repeated.

[0010] Embodiment 1. <Configuration of a power converter> Figure 1 is a circuit diagram of the power converter 100 according to Embodiment 1. Figure 2 is a perspective view of the power converter 100 according to Embodiment 1. Figure 3 is a plan view of the power converter 100 according to Embodiment 1. Figure 4 is a cross-sectional view of the line segment IV-IV in Figure 3. Figure 5 is a cross-sectional view of the line segment VV in Figure 3.

[0011] The power conversion device 100 shown in FIGS. 1 to 5 is, for example, a power conversion device 100 that converts a DC voltage into an AC voltage, and includes a capacitor module 1 that smoothes the voltage, a power module 2 that converts a DC (Direct Current) voltage into an AC (Alternating Current) voltage, and a wiring member 30 electrically connected to the capacitor module 1 and the power module 2. The wiring member 30 includes a high-potential side wiring member 30h and a low-potential side wiring member 30l. The high-potential side wiring member 30h is composed of a capacitor high-potential side wiring member 31h, a power module high-potential side wiring member 32h, and semiconductor element wiring members 34a and 34b. The low-potential side wiring member 30l is composed of a capacitor low-potential side wiring member 31l, a power module low-potential side wiring member 32l, and a semiconductor element wiring member 34c.

[0012] First, the electrical circuit of the power conversion device 100 according to Embodiment 1 will be described. As shown in FIG. 1, the capacitor module 1 includes a capacitor element 12, a capacitor high-potential side wiring member 31h, and a capacitor low-potential side wiring member 31l. Here, six capacitor elements 12a, 12b, 12c, 12d, 12e, and 12f are arranged as the capacitor element 12. The capacitor elements 12a, 12b, 12c, 12d, 12e, and 12f are connected in parallel. The capacitor high-potential side wiring member 31h is connected to the high-potential side of the capacitor element 12. The capacitor high-potential side wiring member 31h is connected to the high-potential side terminal portion 33h of the power module at the other end side, which is opposite to the one end connected to the high-potential side of the capacitor element 12. The capacitor low-potential side wiring member 31l is connected to the low-potential side of the capacitor element 12. The capacitor low-potential side wiring member 31l is connected to the low-potential side terminal portion 33l of the power module at the other end side, which is opposite to the one end connected to the low-potential side of the capacitor element 12.

[0013] In the first embodiment, film capacitors are used for the six capacitor elements 12a, 12b, 12c, 12d, 12e, and 12f, respectively, but other types of capacitors may also be used. Further, although the six capacitor elements 12a, 12b, 12c, 12d, 12e, and 12f are connected in parallel, for example, they may be connected in series, or may be connected in a series-parallel combination of series connection and parallel connection.

[0014] In the first embodiment, the internal circuit of the power module 2 is a three-phase full-bridge type inverter circuit. The power module 2 includes switching elements 20, 21, a power module high-potential side wiring member 32h, and a power module low-potential side wiring member 32l. In the first embodiment, the switching elements 20, 21 are high-potential side IGBT elements 20a, 20b, 20c for three phases, high-potential side diode elements 20d, 20e, 20f, low-potential side IGBT elements 21a, 21b, 21c, and low-potential side diode elements 21d, 21e, 21f, respectively. The power module high-potential side wiring member 32h includes a power module high-potential side terminal portion 33h. The power module high-potential side wiring member 32h is connected to the collector electrodes of the high-potential side IGBT elements 20a, 20b, 20c on the other end side located at a position opposite to one end including the power module high-potential side terminal portion 33h. Each of the high-potential side diode elements 20d, 20e, 20f is connected in anti-parallel to the high-potential side IGBT elements 20a, 20b, 20c. The power module low-potential side wiring member 32l includes a power module low-potential side terminal portion 33l. The power module low-potential side wiring member 32l is connected to the emitter electrodes of the low-potential side IGBT elements 21a, 21b, 21c on the other end side located at a position opposite to one end including the power module low-potential side terminal portion 33l. Each of the low-potential side diode elements 21d, 21e, 21f is connected in anti-parallel to the low-potential side IGBT elements 21a, 21b, 21c.

[0015] In this embodiment 1, the internal circuit of the power module 2 is a three-phase full-bridge inverter circuit, but other inverter circuits may also be used. For example, the internal circuit of the power module 2 may be a single-phase inverter, a dual three-phase inverter, or a multi-level inverter circuit such as a three-level inverter circuit. Also, although this embodiment 1 shows a power module 2 that includes all inverter circuits, the power module 2 may also be composed of individual power elements. The power elements may be IGBT elements, or for example, MOSFETs.

[0016] Next, the configuration of the power converter 100 in this embodiment 1 will be described. As shown in Figures 2 to 5, the capacitor module 1 and the power module 2 are arranged on the upper surface of the cooler 3. The cooler 3 only needs to be able to transfer the heat generated in the capacitor module 1 and the power module 2 and transfer that heat to the outside (for example, the surrounding space), and any configuration can be adopted. For example, the cooler 3 can dissipate heat through convection and radiation to the surrounding space via its surface. Alternatively, a refrigerant channel, as described later, may be formed in the cooler 3, and heat may be transferred to the outside via the refrigerant flowing through the refrigerant channel. Therefore, the cooler 3 may be, for example, a housing that houses the capacitor module 1 and the power module. Alternatively, the cooler 3 may be a separate component from the housing and connected to the housing. The material of the cooler 3 may be a metallic material such as aluminum (Al) or iron (Fe).

[0017] As shown in Figures 4 and 5, a refrigerant channel 4 through which a refrigerant such as cooling water flows may be formed on the upper surface of the cooling body 3. The power module 2 is positioned directly above the refrigerant channel 4. By positioning the power module 2 directly above the refrigerant channel 4 in this way, the power module 2 is cooled. Furthermore, in order to cool the capacitor element 12 more effectively, the refrigerant channel 4 may be formed directly below the capacitor module 1, for example. Note that the cooling method for the power module 2 may be an air-cooling method in which a cooling gas such as air flows through the refrigerant channel 4, rather than a chilled water method in which cooling water flows through the refrigerant channel 4.

[0018] The capacitor module 1 is electrically connected to the power module 2 by a capacitor high-potential side wiring member 31h and a capacitor low-potential side wiring member 31l. The capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l are each connected to the cooler 3 via a thermally conductive insulating member 5. The heat generated in the capacitor element 12 is dissipated into the coolant flow path 4 via the thermally conductive insulating member 5 and the cooler 3. As a result, the capacitor element 12 is cooled. The material of the thermally conductive insulating member 5 is, for example, silicone resin. The material of the thermally conductive insulating member 5 may also be a resin material containing a thermally conductive filler.

[0019] As shown in Figures 4 and 5, the capacitor module 1 consists of a capacitor case 11, a capacitor element 12, a capacitor high-potential side wiring member 31h, a capacitor low-potential side wiring member 31l, and a capacitor encapsulant 13. The capacitor element 12, the capacitor high-potential side wiring member 31h, the capacitor low-potential side wiring member 31l, and the capacitor encapsulant 13 are arranged inside the capacitor case 11. The capacitor element 12 is positioned so as to be sandwiched between the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l.

[0020] The capacitor high-potential side wiring member 31h is connected to the capacitor element 12. The capacitor case 11 has a through hole H. Each of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l extends from the inside to the outside of the capacitor case 11 through the through hole H. As shown in Figure 5, the capacitor high-potential side wiring member 31h extends to the outside of the capacitor case 11 through the through hole H at the other end opposite to the end connected to the capacitor element 12. The capacitor high-potential side wiring member 31h is connected to the power module high-potential side terminal portion 33h at the other end opposite to the end connected to the capacitor element 12. The capacitor low-potential side wiring member 31l is connected to the capacitor element 12. As shown in Figure 4, the capacitor low-potential side wiring member 31l extends to the outside of the capacitor case 11 through the through hole H at the other end opposite to the end connected to the capacitor element 12. The capacitor low-potential side wiring member 31l is connected to the power module low-potential side terminal portion 33l at the other end opposite to the end connected to the capacitor element 12. The capacitor encapsulant 13 fills the inside of the capacitor case 11, encapsulating the capacitor element 12 and the capacitor high-potential side wiring member 31h and capacitor low-potential side wiring member 31l, excluding the portion that extends outside the capacitor case 11. The material of the capacitor case 11 is, for example, PET (PolyEthyleneTerephthalate) resin. The material of the capacitor case 11 can be any engineering plastic with excellent heat resistance, so in addition to PET resin, PPS (Polyphenylene Sulfide) resin and PBT (PolyButyleneTerephthalate) resin may also be used.

[0021] The power module 2 is composed of switching elements 20 and 21, a power module high-potential side wiring member 32h, a power module low-potential side wiring member 32l, semiconductor element wiring members 34a, 34b, and 34c, an insulating member 25, a heat sink 26, a power module encapsulant 23, and a power module case 24. In this embodiment 1, the power module 2 is integrated with the heat sink 26, but for example, the power module 2 may be configured without a built-in heat sink 26. In this case, the power module 2 may have a structure in which the heat sink 26 is attached separately. The material of the power module case 24 is, for example, PET resin. The material of the power module case 24 can be any engineering plastic with excellent heat resistance, so in addition to PET resin, PPS resin and PBT resin may also be used.

[0022] On the low-potential side of power module 2, as shown in Figure 4, the low-potential IGBT element 21a and the low-potential diode element 21d are arranged on the upper surface of the semiconductor element wiring member 34c. The semiconductor element wiring member 34c is connected to the insulating member 25 on the surface opposite to the surface on which the low-potential IGBT element 21a and the low-potential diode element 21d are arranged. The low-potential IGBT element 21a and the low-potential diode element 21d are connected to the power module low-potential wiring member 32l on the surface opposite to the surface on which they are connected to the semiconductor element wiring member 34c. The anode of the low-potential diode element 21d is connected to the power module low-potential wiring member 32l, and the cathode is connected to the semiconductor element wiring member 34c. The emitter of the low-potential IGBT element 21a is connected to the power module low-potential wiring member 32l, and the collector is connected to the semiconductor element wiring member 34c. The power module low-potential side wiring member 32l has a power module low-potential side terminal portion 33l that extends to the outside of the power module case 24 at the other end opposite to the one end connected to the low-potential side IGBT element 21a and the low-potential side diode element 21d.

[0023] On the high-potential side of power module 2, as shown in Figure 5, the high-potential side IGBT element 20a and the high-potential side diode element 20d are arranged on the upper surface of the semiconductor element wiring member 34b. The semiconductor element wiring member 34b is connected to the insulating member 25 on the surface opposite to the surface on which the high-potential side IGBT element 20a and the high-potential side diode element 20d are arranged. The high-potential side IGBT element 20a and the high-potential side diode element 20d are connected to the semiconductor element wiring member 34a on the surface opposite to the surface on which they are connected. The cathode of the high-potential side diode element 20d is connected to the semiconductor element wiring member 34b, and the anode is connected to the semiconductor element wiring member 34a. The collector of the high-potential side IGBT element 20a is connected to the semiconductor element wiring member 34b, and the emitter is connected to the semiconductor element wiring member 34a. The semiconductor element wiring member 34b is connected to the power module high-potential side wiring member 32h on the side where the high-potential side IGBT element 20a and the high-potential side diode element 20d are located. The power module high-potential side wiring member 32h has a power module high-potential side terminal portion 33h that extends to the outside of the power module case 24 at the other end opposite to the end connected to the high-potential side IGBT element 20a and the high-potential side diode element 20d.

[0024] On both the high-potential and low-potential sides, the insulating member 25 is connected to the heat sink 26 on the side opposite to the side on which the switching elements 20 and 21 are located. The heat sink 26 is mounted on the cooling body 3 such that the side opposite to the side connected to the insulating member 25 becomes the inner wall of the refrigerant flow path 4 (blocking the refrigerant flow path 4). In this way, a sealed refrigerant flow path 4 is formed. The heat sink 26 is cooled by the cooling water or cooling air flowing through the refrigerant flow path 4. As a result, the switching elements 20 and 21 are cooled via the insulating member 25 and the semiconductor element wiring members 34b and 34c.

[0025] The power module encapsulant 23 seals the switching elements 20 and 21, the semiconductor element wiring members 34a, 34b, and 34c, and the insulating member 25 so as to fill the area surrounded by the power module case 24 and the heat sink 26. The material of the power module encapsulant 23 is, for example, a silicone gel material.

[0026] Herein, a feature of the power conversion device 100 according to this embodiment 1 is that, as shown in Figures 2 to 5, the thermal conductive insulating member 5 is arranged such that the thermal resistance of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in the region from the capacitor module 1 to the thermal conductive insulating member 5 is smaller than the thermal resistance of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in the region from the power module 2 to the thermal conductive insulating member 5.

[0027] Specifically, the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l have a first contact portion 5a and a second contact portion 5b. As shown in Figures 4 and 5, the portion where the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l pass through the through-hole H of the capacitor case 11 is defined as the first contact portion 5a. The portion where the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l connect to the power module high-potential side terminal portion 33h and the power module low-potential side terminal portion 33l, respectively, is defined as the second contact portion 5b. In each of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l, the portion connected to the thermally conductive insulating member 5 is defined as the third contact portion 5c. For example, the third contact portion 5c may be the portion of the wiring member that overlaps with the central part of the thermally conductive insulating member 5 in the direction along the extending direction of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l, as shown in Figures 4 and 5. When the cross-sectional shape of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l (shape in a cross section perpendicular to the extending direction of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l) is uniform from the first contact portion 5a to the second contact portion 5b in a side view of the power converter 100, the distance L1 is made smaller than the distance L2. In this case, the thermal resistance of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in the region from the capacitor module 1 to the thermally conductive insulating member 5 becomes smaller than the thermal resistance of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in the region from the power module 2 to the thermally conductive insulating member 5.

[0028] As shown in Figures 4 and 5, distance L1 is the distance along the surface of the thermally conductive insulating member 5 from the first contact portion 5a to the third contact portion 5c in a side view of the power converter 100. Distance L2 is the distance along the surface of the thermally conductive insulating member 5 from the second contact portion 5b to the third contact portion 5c in a side view of the power converter 100.

[0029] When the cross-sectional shapes of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l are uniform from the first contact portion 5a to the second contact portion 5b, the thermally conductive insulating member 5 should be arranged such that the third contact portion 5c is on the capacitor side of the midpoint between the first contact portion 5a and the second contact portion 5b on both the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l. The midpoint is a point on the surface of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l, where the distance L1 is equal to the distance L2.

[0030] Figure 6 is a plan view showing a modified example of the power converter 100 according to this embodiment 1. The power converter 100 shown in Figure 6 basically has the same configuration as the power converter 100 shown in Figures 1 to 5, but differs from the power converter 100 shown in Figures 1 to 5 in that the cross-sectional shapes of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l are not uniform. Specifically, as shown in Figure 6, in a plan view of the wiring member 30 viewed from a direction perpendicular to the upper surface of the cooling body 3, the width in the Y direction near the first contact portion 5a of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l is smaller than the width in the Y direction near the second contact portion 5b. Thus, if the cross-sectional shapes of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l are not uniform from the first contact portion 5a to the second contact portion 5b, the thermal conductive insulating member 5 should be positioned such that, considering Fourier's law described later, the thermal resistance of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in the region from the capacitor module 1 to the thermal conductive insulating member 5 is smaller than the thermal resistance of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in the region from the power module 2 to the thermal conductive insulating member 5. In this way, the amount of heat generated in the capacitor element 12 and dissipated to the refrigerant flow path 4 via the thermal conductive insulating member 5 and the coolant body 3 increases. As a result, the cooling performance of the capacitor element 12 is improved. For example, in the power converter 100 shown in Figure 6, the thermal conductive insulating member 5 may be positioned closer to the capacitor module 1 so that the distance L1 is smaller than in the power converter 100 shown in Figures 4 and 5. Furthermore, in the plan view shown in Figure 6, the width in the Y direction near the first contact portion 5a of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l may be greater than the width in the Y direction near the second contact portion 5b.

[0031] Considering the flow of heat as analogous to the flow of electricity, in this embodiment 1, the thermal resistance R (unit: K / W) of the thermally conductive insulating member 5 can be expressed by the following equation (1) from Fourier's law. The distance L (unit: m) is the distance along the surface of the wiring member 30. Cross-sectional area A (unit: m 2 ) is the cross-sectional area of ​​the wiring member 30 in a section perpendicular to the direction along the surface of the wiring member 30. Thermal conductivity (unit: W / (m·K)) is a physical property value determined by the material of the wiring member 30.

[0032]

number

[0033] The cooling action of the capacitor element 12 in the power conversion device 100 according to this embodiment 1 will be described below.

[0034] In the power converter 100 according to this embodiment 1, the heat generated on the low-potential side includes heat Q21 generated in the low-potential side IGBT element 21a and the low-potential side diode element 21d in conjunction with the operation of the low-potential side IGBT element 21a and the low-potential side diode element 21d, Joule heat Q19 generated in the power module low-potential side wiring member 32l due to current flow from the low-potential side IGBT element 21a and the low-potential side diode element 21d, Joule heat Q15 generated in the capacitor low-potential side wiring member 31l due to current flow from the low-potential side IGBT element 21a and the low-potential side diode element 21d, and Joule heat Q12 generated in the capacitor element 12 due to current flow from the low-potential side IGBT element 21a and the low-potential side diode element 21d.

[0035] Most of the heat Q21 is dissipated into the refrigerant flow path 4 via the semiconductor element wiring member 34c, the insulating member 25, and the heat sink 26. The remaining heat Q21 is dissipated into the refrigerant flow path 4 via the power module low-potential side wiring member 32l, the capacitor low-potential side wiring member 31l, the thermally conductive insulating member 5, and the cooler 3. The remaining heat Q21 dissipated via this thermally conductive insulating member 5 is referred to as heat quantity Q211.

[0036] Most of the heat from the Joule heat Q19 is dissipated into the coolant flow path 4 via the low-potential side IGBT element 21a, the low-potential side diode element 21d, the semiconductor element wiring member 34c, the insulating member 25, and the heat sink 26. The remaining Joule heat Q19 is dissipated into the coolant flow path 4 via the capacitor low-potential side wiring member 31l, the thermally conductive insulating member 5, and the cooler 3. The amount of heat from the remaining Joule heat Q19 dissipated via the thermally conductive insulating member 5 is denoted as heat quantity Q191.

[0037] The amount of heat in the Joule heat Q15 includes the amount of heat dissipated into the refrigerant flow path 4 via the power module low-potential side wiring member 32l, low-potential side IGBT element 21a and low-potential side diode element 21d, semiconductor element wiring member 34c, insulating member 25 and heat sink 26, and the amount of heat dissipated into the refrigerant flow path 4 via the thermally conductive insulating member 5 and cooler 3. Of this Joule heat Q15, the amount of Joule heat Q15 dissipated into the refrigerant flow path 4 via the thermally conductive insulating member 5 and cooler 3 is defined as the amount of heat Q151.

[0038] Strictly speaking, a portion of the Joule heat Q15 is dissipated into the refrigerant flow path 4 via the capacitor encapsulant 13, capacitor case 11, and coolant 3. However, while the thermal conductivity of the copper material used for the capacitor low-potential side wiring member 31l is 398 W / (m·K), the thermal conductivity of the epoxy resin material used for the capacitor encapsulant 13 and the PET resin material used for the capacitor case 11 are relatively small at 0.2 W / (m·K) and 0.3 W / (m·K), respectively. Therefore, compared to the heat quantity Q151, the amount of heat dissipated into the refrigerant flow path 4 via the capacitor encapsulant 13, capacitor case 11, and coolant 3 is negligibly small and will not be considered here.

[0039] Joule heat Q12 is dissipated into the refrigerant flow path 4 via the capacitor low-potential side wiring member 31l, the thermally conductive insulating member 5, and the cooler 3. The amount of heat from this Joule heat Q15 is denoted as heat quantity Q151. Strictly speaking, a portion of the Joule heat Q12 is dissipated into the refrigerant flow path 4 via the capacitor encapsulant 13, the capacitor case 11, and the cooler 3, but like Joule heat Q15, the amount of heat dissipated into the refrigerant flow path 4 via the capacitor encapsulant 13, the capacitor case 11, and the cooler 3 is negligibly small and therefore not considered.

[0040] Furthermore, while the aforementioned Joule heat Q12, Q15, Q19, and heat Q21 include the amount of heat dissipated to the surrounding air through the capacitor case 11 or power module case 24, considering the thermal conductivity and convective heat transfer coefficient of the constituent materials, the amount of heat dissipated to the surrounding air through the capacitor case 11 or power module case 24 is negligibly small and therefore not considered.

[0041] Based on the above, in the power converter 100 according to this embodiment 1, thermal conductive insulation on the low potential side Component 5 The total amount of heat Q1 passing through is expressed by the equation shown in equation (2) below.

[0042]

number

[0043] In addition, the high-potential side configuration of the power converter 100 according to this embodiment 1 differs from the low-potential side configuration in that the capacitor high-potential side wiring member 31h is connected to the upper surface of the capacitor element 12 (the surface opposite to the cooling body 3 when viewed from the capacitor element 12), and the power module high-potential side wiring member 32h is connected to the semiconductor element wiring member 34b instead of the switching elements 20 and 21. Except for the two points mentioned above, the high-potential side configuration is the same as the low-potential side configuration, so the cooling effect on the high-potential side is the same as the cooling effect on the low-potential side.

[0044] Here, the amount of heat generated in the high-potential-side IGBT element 20a and the high-potential-side diode element 20d due to their operation is denoted as heat quantity Q202, which is dissipated into the refrigerant flow path 4 via the semiconductor element wiring member 34b, the power module high-potential-side wiring member 32h, the capacitor high-potential-side wiring member 31h, the thermally conductive insulating member 5, and the coolant 3.

[0045] Of the Joule heat generated in the power module's high-potential side wiring member 32h, the amount of heat dissipated to the refrigerant flow path 4 via the capacitor's high-potential side wiring member 31h, the thermally conductive insulating member 5, and the coolant 3 is defined as the heat quantity Q182.

[0046] Of the Joule heat generated in the high-potential side wiring member 31h of the capacitor, the amount of heat dissipated to the refrigerant flow path 4 via the thermally conductive insulating member 5 and the coolant body 3 is defined as heat quantity Q142.

[0047] Of the Joule heat Q12 generated in the capacitor element 12, the amount of Joule heat Q12 that is dissipated to the refrigerant flow path 4 via the capacitor high-potential side wiring member 31h, the thermally conductive insulating member 5, and the coolant 3 is defined as the heat quantity Q122.

[0048] Based on the above, in the power converter 100 according to this embodiment 1, thermal conductive insulation on the high potential side Component 5 The total amount of heat Q2 passing through is expressed by the equation shown in equation (3) below.

[0049]

number

[0050] <Effects and Effects> A power converter 100 according to this disclosure comprises a capacitor element 12, switching elements 20 and 21, a wiring member 30, a cooling body 3, and a thermally conductive insulating member 5. The wiring member 30 is electrically connected to the capacitor element 12 and the switching elements 20 and 21. The cooling body 3 mounts the capacitor element 12 and the switching elements 20 and 21. The thermally conductive insulating member 5 is connected to the cooling body 3 and the wiring member 30. The wiring member 30 has a first contact portion 5a and a second contact portion 5b. The wiring member 30 is connected to the capacitor element 12 at the first contact portion 5a. The wiring member 30 is connected to the switching elements 20 and 21 at the second contact portion 5b. The thermal resistance of the wiring member 30 in the region from the first contact portion 5a to the thermally conductive insulating member 5 is smaller than the thermal resistance of the wiring member 30 in the region from the second contact portion 5b to the thermally conductive insulating member 5.

[0051] In this way, the thermal resistance of the wiring member 30 in the region from the first contact portion 5a to the thermally conductive insulating member 5 is smaller than the thermal resistance of the wiring member 30 in the region from the second contact portion 5b to the thermally conductive insulating member 5. Therefore, the heat generated in the capacitor element 12 can be effectively transferred to the cooler 3 via the wiring member 30 and the thermally conductive insulating member 5. As a result, the temperature rise of the capacitor element 12 due to the heat Q12 generated in the capacitor element 12 can be suppressed. On the other hand, the temperature rise of the thermally conductive insulating member 5 due to the heat Q20 and heat Q21 generated in the switching elements 20 and 21, the heat Q19 generated in the low-potential side wiring member 32l of the power module, and the heat Q18 generated in the high-potential side wiring member 32h of the power module is reduced. As a result, the temperature rise of the capacitor element 12 due to the temperature rise of the thermally conductive insulating member 5 can be suppressed, and consequently, the temperature rise of the capacitor element 12 can be suppressed.

[0052] In the above-mentioned power converter 100, when the portion of the wiring member 30 connected to the thermally conductive insulating member 5 is designated as the third contact portion 5c, the distance L1 from the first contact portion 5a to the third contact portion 5c is smaller than the distance L2 from the second contact portion 5b to the third contact portion 5c.

[0053] In this way, when the cross-sectional shape of the wiring member 30 is uniform, the thermal resistance of the wiring member 30 in the region from the first contact portion 5a to the thermally conductive insulating member 5 becomes smaller than the thermal resistance of the wiring member 30 in the region from the second contact portion 5b to the thermally conductive insulating member 5, thereby suppressing the temperature rise of the capacitor element 12.

[0054] In the power conversion device 100 described above, a refrigerant flow path 4 is formed in the cooling body 3 at a position opposite to the switching elements 20 and 21. In this case, the heat transferred from the thermally conductive insulating member 5 to the cooling body 3 can be effectively removed by the refrigerant flowing through the refrigerant flow path 4, and the switching elements 20 and 21 can be efficiently cooled.

[0055] To verify the effectiveness of the power converter 100 according to this embodiment 1 as described above, the following simulation was performed.

[0056] <Analysis conditions> Regarding a power converter as Embodiment 1, which has a configuration similar to the power converter 100 shown in Figures 1 to 5, the temperature rise in the capacitor element was determined by simulation when the temperature of the low-potential side IGBT element 21a, the low-potential side diode element 21d, the semiconductor element wiring member 34b, and the cooler 3 were set to 120°C, 120°C, 80°C, and 70°C respectively, and the position of the thermally conductive insulating member was changed. The ripple current flowing from the power module 2 to the capacitor module 1 was set to 200 Arms.

[0057] <Analysis results> Table 1 shows the simulation results for Example 1 under the above analysis conditions. In Table 1, the ratio of the positions of the thermally conductive insulating member 5 is the value obtained by dividing the distance L1 from the first contact portion 5a to the third contact portion 5c by the distance (distance L1 + distance L2) from the first contact portion 5a to the second contact portion 5b. As can be seen from Table 1, the temperature of the capacitor element 12 after static decomposition in Example 1 is lower when the ratio of the positions of the thermally conductive insulating member 5 is less than 50% than when the ratio of the positions of the thermally conductive insulating member 5 is 50% or more. In other words, when the cross-sectional shape of the wiring member 30 is uniform, placing the thermally conductive insulating member 5 closer to the first contact portion 5a than to the second contact portion 5b can suppress the temperature rise of the capacitor element 12.

[0058] [Table 1]

[0059] Embodiment 2. <Configuration of a power converter> Figure 7 is a circuit diagram of the power converter 100 according to Embodiment 2. Figure 7 corresponds to Figure 1. Figure 8 is a perspective view of the power converter 100 according to Embodiment 2. Figure 8 corresponds to Figure 2. Figure 9 is a plan view of the power converter 100 according to Embodiment 2. Figure 9 corresponds to Figure 3. Figure 10 is a cross-sectional view of line segment XX in Figure 9. Figure 10 corresponds to Figure 4. Figure 11 is a cross-sectional view of line segment XI-XI in Figure 9. Figure 11 corresponds to Figure 5.

[0060] The power converter 100 shown in Figures 7 to 11 has basically the same configuration as the power converter 100 shown in Figures 1 to 5, but differs from the power converter 100 shown in Figures 1 to 5 in that it lacks the thermally conductive insulating member 5 on the high potential side. Also, the circuit of the power converter 100 shown in Figure 7 differs from the circuit of the power converter 100 shown in Figure 1 in that it is composed of three capacitor elements 12.

[0061] The power converter 100 according to this second embodiment can be designed to accommodate a small ripple current flowing through the capacitor module 1. Because the ripple current flowing through the capacitor module 1 is small, the number of capacitor elements 12 connected in parallel within the capacitor module 1 may be, for example, three. In addition, in this second embodiment, in addition to having three capacitor elements 12, the external shape of the capacitor module 1 in this second embodiment can be made smaller than the external shape of the capacitor module 1 in the first embodiment. Furthermore, because the ripple current flowing through the capacitor module 1 is small, the cross-sectional areas of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in this second embodiment may be smaller than the cross-sectional areas of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l in the first embodiment, and may be, for example, 38% smaller.

[0062] In the power converter 100 of this second embodiment, because the ripple current is small, the resistance loss generated in the capacitor element 12, the capacitor high-potential side wiring member 31h, the power module high-potential side wiring member 32h, the power module low-potential side wiring member 32l, and the capacitor low-potential side wiring member 31l, through which the ripple current flows, is small. For this reason, in this second embodiment, the thermally conductive insulating member 5 is placed only on the low-potential side.

[0063] The structure within the power module 2 on the high-potential side, viewed from the heat sink 26, consists of an insulating member 25, a semiconductor element wiring member 34b, a high-potential side IGBT element 20a, and a high-potential side diode element 20d, each of which are surface-bonded in that order. In addition, the power module's high-potential side wiring member 32h is also bonded to the semiconductor element wiring member 34b.

[0064] On the other hand, the structure within the power module 2 on the low-potential side, as viewed from the heat sink 26, has a structure in which the insulating member 25, the semiconductor element wiring member 34c, the low-potential side IGBT element 21a, and the low-potential side diode element 21d are each surface-bonded in that order. Therefore, the low-potential side IGBT element 21a and the low-potential side diode element 21d become hotter than the semiconductor element wiring member 34c. As a result, the power module low-potential side wiring member 32l, which is connected to the low-potential side IGBT element 21a and the low-potential side diode element 21d, becomes hotter than the power module high-potential side wiring member 32h, which is connected to the semiconductor element wiring member 34b. Therefore, connecting the thermally conductive insulating member 5 to the power module low-potential side wiring member 32l is more effective in improving the cooling performance of the capacitor element 12 than connecting it to the power module high-potential side wiring member 32h.

[0065] In this way, the thermally conductive insulating member 5 only needs to be attached in one place, simplifying the structure of the power conversion device 100 according to this embodiment 2.

[0066] <Effects and Effects> In the power converter 100 described above, the switching elements 20 and 21 have wiring members 30 connected to the opposite side of the switching elements 20 and 21 from the side facing the cooling body 3. The thermally conductive insulating member 5 is connected only to the cooling body 3 and the wiring members 30. In this way, even though the wiring members 30 are connected to the opposite side of the switching elements 20 and 21 from the side facing the cooling body 3, the heat generated by the switching elements 20 and 21 can be dissipated to the cooling body 3 via the thermally conductive insulating member 5. As a result, the temperature rise of the capacitor element 12 due to the heat generated by the switching elements 20 and 21 can be suppressed, and consequently, the cooling performance of the capacitor element 12 can be improved.

[0067] In the power converter 100 described above, the switching elements 20 and 21 include a high-potential side switching element 20 and a low-potential side switching element 21. The wiring member 30 includes a high-potential side wiring member 30h and a low-potential side wiring member 30l. The high-potential side switching element 20 has the high-potential side wiring member 30h connected to the side facing the cooling body 3. The low-potential side switching element 21 has the low-potential side wiring member 30l connected to the side opposite to the side facing the cooling body 3. The thermally conductive insulating member 5 is connected only to the cooling body 3 and the low-potential side wiring member 30l. In this way, even if there are multiple wiring members 30 connecting the capacitor element 12 and the switching elements 20 and 21, it is not necessary to attach the thermally conductive insulating member 5 to all wiring members 30, and the number of components constituting the power converter 100 can be reduced. As a result, the structure of the power converter 100 can be simplified.

[0068] To verify the effectiveness of the power converter 100 according to this embodiment 2 as described above, the following simulation was performed.

[0069] <Analysis conditions> For the power conversion devices of Examples 2 and 3, the temperature rise in the capacitor element was simulated when the position of the thermally conductive insulating member was changed, while the temperatures of the low-potential side IGBT element 21a, the low-potential side diode element 21d, the semiconductor element wiring member 34b, and the cooler 3 were set to 120°C, 120°C, 80°C, and 70°C, respectively. The ripple current flowing from the power module 2 to the capacitor module 1 was set to 100 Arms. Example 2 has the same configuration as the power conversion device 100 according to Example 2, and the thermally conductive insulating member 5 is located only on the low-potential side. In Example 3, the thermally conductive insulating member 5 is not located on the low-potential side, but only on the high-potential side.

[0070] <Analysis results> Table 2 shows the simulation results under the above conditions.

[0071] [Table 2]

[0072] As can be seen from Table 2, in all comparisons of the ratio of positions of the thermally conductive insulating member 5, the temperature of the capacitor element 12 after static determination in Example 2 is lower than the temperature of the capacitor element 12 after static determination in Example 3. Furthermore, in both Example 2 and Example 3, the temperature of the capacitor element 12 after static determination is relatively lower when the ratio of positions of the thermally conductive insulating member 5 is less than 50% than when the ratio of positions of the thermally conductive insulating member 5 is 50% or more. This is the same as the simulation results for the power conversion device 100 according to Embodiment 1.

[0073] Embodiment 3. <Configuration of a power converter> Figures 12 and 13 are cross-sectional views of the power converter 100 according to Embodiment 3. Figure 12 corresponds to Figure 4. Figure 13 corresponds to Figure 5.

[0074] The power converter 100 shown in Figures 12 and 13 has basically the same configuration as the power converter 100 shown in Figures 1 to 5, but differs from the power converter 100 shown in Figures 1 to 5 in that the entire thermal conductive insulating member 5 is located on the capacitor side of the midpoint between the first contact portion 5a and the second contact portion 5b. Specifically, as shown in Figures 12 and 13, the third contact portion 5c is the portion of the wiring member that overlaps with one end of the thermal conductive insulating member 5 (the point furthest from the first contact portion 5a) in the direction along the extending direction of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l.

[0075] The third contact portion 5c may be positioned closer to the capacitor element 12 than the midpoint between the first contact portion 5a and the second contact portion 5b. In other words, in the direction along the extending direction of the capacitor high-potential side wiring member 31h and the capacitor low-potential side wiring member 31l, both ends of the thermally conductive insulating member 5 may be positioned closer to the capacitor than the midpoint between the first contact portion 5a and the second contact portion 5b.

[0076] In this way, the thermally conductive insulating member 5 is placed on the capacitor element 12 side, which further suppresses the temperature rise of the capacitor element 12.

[0077] <Effects and Effects> In the power conversion device 100 described above, the entire thermally conductive insulating member 5 is located on the capacitor element 12 side of the midpoint between the first contact portion 5a and the second contact portion 5b. This arrangement further suppresses the temperature rise of the capacitor element 12.

[0078] Embodiment 4. <Configuration of a power converter> Figures 14 and 15 are cross-sectional views of the power converter 100 according to Embodiment 4. Figure 14 corresponds to Figure 4. Figure 15 corresponds to Figure 5.

[0079] The power converter 100 shown in Figures 14 and 15 has basically the same configuration as the power converter 100 shown in Figures 1 to 5, but differs from the power converter 100 shown in Figures 1 to 5 in that the thermally conductive insulating member 5 is in contact with the capacitor element 12. Specifically, the thermally conductive insulating member 5 is in contact with the side surface of the capacitor case 11, thereby indirectly contacting the capacitor element 12. The capacitor module 1 is composed of the capacitor element 12, the capacitor high-potential side wiring member 31h, and the capacitor low-potential side wiring member 31l, and the thermally conductive insulating member 5 may be in direct contact with the capacitor element 12.

[0080] In this way, the thermally conductive insulating member 5 is placed on the capacitor element 12 side, which further suppresses the temperature rise of the capacitor element 12.

[0081] <Effects and Effects> In the power conversion device 100 described above, the thermally conductive insulating member 5 is in contact with the capacitor element 12. This further suppresses the temperature rise of the capacitor element 12.

[0082] The embodiments disclosed herein should be considered in all respects to be illustrative and not restrictive. At least two of the embodiments disclosed herein can be combined, as long as they do not contradict each other. The basic scope of this disclosure is indicated by the claims rather than the foregoing description, and all modifications within the meaning and scope of the claims are intended to be included.

[0083] The various aspects of this disclosure are summarized below as an appendix. (Note 1) Capacitor element and Switching element and A wiring member electrically connected to the capacitor element and the switching element, A cooling body equipped with the capacitor element and the switching element, The cooling body and the thermally conductive insulating member connected to the wiring member are provided. The wiring member has a first contact portion and a second contact portion, The wiring member is connected to the capacitor element at the first contact portion. The wiring member is connected to the switching element at the second contact portion. A power converter wherein the thermal resistance of the wiring member in the region from the first contact portion to the thermally conductive insulating member is smaller than the thermal resistance of the wiring member in the region from the second contact portion to the thermally conductive insulating member. (Note 2) In the aforementioned wiring member, when the portion connected to the thermally conductive insulating member is designated as the third contact portion, The power conversion device as described in Appendix 1, wherein the distance from the first contact portion to the third contact portion is smaller than the distance from the second contact portion to the third contact portion. (Note 3) The switching element has the wiring member connected to the side opposite to the side facing the cooling body. The power conversion device according to Appendix 1 or Appendix 2, wherein the thermally conductive insulating member is connected only to the cooling body and the wiring member. (Note 4) The switching element includes a high-potential side switching element and a low-potential side switching element. The wiring member includes a high-potential side wiring member and a low-potential side wiring member. The high-potential-side switching element has the high-potential-side wiring member connected to the surface facing the cooling body. The low-potential side switching element has the low-potential side wiring member connected to the side opposite to the side facing the cooling body. The power conversion device according to Appendix 1 or Appendix 2, wherein the thermally conductive insulating member is connected only to the cooling body and the low-potential side wiring member. (Note 5) The power conversion device according to any one of the appendices 1 to 4, wherein a coolant flow path is formed in the cooling body at a position opposite to the switching element. (Note 6) The power conversion device according to any one of the appendices 1 to 5, wherein the entire thermally conductive insulating member is located on the capacitor element side of the midpoint between the first contact portion and the second contact portion. (Note 7) The power conversion device according to any one of the appendices 1 to 6, wherein the thermally conductive insulating member is in contact with the capacitor element. [Explanation of Symbols]

[0084] 1 Capacitor module, 2 Power module, 3 Cooling element, 4 Coolant flow path, 5 Thermally conductive insulating material, 5a First contact part, 5b Second contact part, 5c Third contact part, 11 Capacitor case, 12 Capacitor element, 13 Capacitor encapsulant, 20, 21 Switching element, 20 High-potential switching element, 20a High-potential IGBT element, 20d High-potential diode element, 21 Low-potential switching element, 21a Low-potential IGBT element, 21d Low-potential diode element, 23 Power module encapsulant, 24 Power module case, 25 Insulating material, 26 Heat sink, 30 Wiring material, 30h High-potential wiring material, 30l Low-potential wiring material, 31h Capacitor high-potential wiring material, 31l Capacitor low-potential wiring material, 32h Power module high-potential wiring material, 32l Power module low-potential wiring material, 33h Power module high-potential side terminal section, 33l Power module low-potential side terminal section, 34a, 34b, 34c Wiring material for semiconductor element, 100 Power converter, L, L1, L2 Distance, H Through hole.

Claims

1. Capacitor element and Switching element and A wiring member electrically connected to the capacitor element and the switching element, Cooling element and The cooling body and the thermally conductive insulating member connected to the wiring member are provided. The wiring member has a first contact portion and a second contact portion, The wiring member is connected to the capacitor element at the first contact portion. The wiring member is connected to the switching element at the second contact portion. A power converter wherein the thermal resistance of the wiring member in the region from the first contact portion to the thermally conductive insulating member is smaller than the thermal resistance of the wiring member in the region from the second contact portion to the thermally conductive insulating member.

2. In the wiring member, when the portion connected to the thermally conductive insulating member is designated as the third contact portion, The power conversion device according to claim 1, wherein the distance from the first contact portion to the third contact portion is smaller than the distance from the second contact portion to the third contact portion.

3. The switching element has the wiring member connected to the side opposite to the side facing the cooling body. The power conversion device according to claim 1 or 2, wherein the thermally conductive insulating member is connected only to the cooling body and the wiring member.

4. The switching element includes a high-potential side switching element and a low-potential side switching element. The wiring member includes a high-potential side wiring member and a low-potential side wiring member. The high-potential-side switching element has the high-potential-side wiring member connected to the surface facing the cooling body. The low-potential side switching element has the low-potential side wiring member connected to the side opposite to the side facing the cooling body. The power conversion device according to claim 1 or claim 2, wherein the thermally conductive insulating member is connected only to the cooling body and the low-potential side wiring member.

5. The power conversion device according to claim 1 or claim 2, wherein a refrigerant flow path is formed in the cooling body at a position opposite to the switching element.

6. The power conversion device according to claim 1 or claim 2, wherein the entire thermally conductive insulating member is located on the capacitor element side of the midpoint between the first contact portion and the second contact portion.

7. The power conversion device according to claim 1 or claim 2, wherein the thermally conductive insulating member is in contact with the capacitor element.

8. The power conversion device according to claim 1 or claim 2, wherein the switching element is mounted on the cooling body.

9. The power conversion device according to claim 8, wherein the capacitor element is mounted on the cooling body.

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