inverter

Abstract

Disclosed is an inverter. An inverter (1) is integrated by an electric component portion (1a) and a cooling portion (1b). A switching module (20) includes a heat sink (102) that is joined to a lower surface of a substrate (101). The cooling portion (1b) includes an electrically conductive cooler (10) that forms a flow path (11) of a refrigerant. The switching module (5) is mounted to the cooler (10) so that a heat radiating portion (102d) of the heat sink (102) is exposed to the inside of the cooler (10). The heat sink (102) and the cooler (10) are electrically insulated by a common mode current suppression structure (21) that is formed of an insulating member.

Description

Technical Field

[0001] The technology disclosed herein relates to an inverter. In particular, it relates to an on-board inverter. Background Technology

[0002] In recent years, the electrification of automobiles has developed rapidly. Hybrid vehicles and electric vehicles that use electricity to run are equipped with high-voltage drive batteries and inverters to rotate the drive motor used for driving.

[0003] The inverter converts the DC voltage from the drive battery into a three-phase AC voltage and outputs it to the drive motor. Therefore, the inverter includes an inverter circuit, which comprises multiple switching elements (semiconductor chips) for switching control. The inverter needs to increase the speed of its switching control to improve its efficiency.

[0004] However, if the speed of the switching control is increased, common-mode current will flow through an unintended current path due to voltage changes. Specifically, common-mode current will flow through a current path via stray capacitance (parasitic capacitance) and ground (ground wire).

[0005] This leads to the generation of high-order harmonic noise (so-called common-mode noise). Common-mode noise can cause malfunctions in nearby electrical equipment and communication interference. Therefore, in order to improve the speed of switching control, common-mode noise must be suppressed.

[0006] Various technical proposals have been made to suppress common-mode noise. For example, Patent Document 1 discloses a technique for reducing common-mode noise generated in a half-bridge circuit, wherein the half-bridge circuit is constructed by connecting two switching elements in series.

[0007] In a half-bridge circuit, the voltage change at the midpoint of the two switching elements is relatively large. Therefore, in the technology of Patent Document 1, the heat sink (second heat sink 19) which is opposite to the conductive plate (midpoint conductive plate 15) at the midpoint portion through the insulating layer 31 is insulated from the ground terminal 24 (in the description of Reference 1, the symbols of Reference 1 are used for convenience).

[0008] This reduces the common-mode noise emitted from the midpoint conductive plate 15.

[0009] Patent Document 1: Japanese Patent Publication No. 2018-195694 Summary of the Invention

[0010] -The technical problem the invention aims to solve-

[0011] In the technology of Patent Document 1, for example, two insulating parts and three heat sinks need to be joined together by end faces to form a plate shape, which has the disadvantages of complex structure and difficulty in manufacturing.

[0012] Therefore, the technology disclosed here achieves the goal of effectively suppressing common-mode noise with a relatively simple structure by focusing on the overall construction of the inverter.

[0013] - Technical solutions for solving technical problems -

[0014] The technology disclosed herein relates to an inverter comprising an electrical assembly section and a cooling section integrated together, the electrical assembly section housing electronic components including a switching module.

[0015] The switching module includes an insulating layer and a heat sink. An electronic circuit, including an inverter circuit, is disposed on the upper surface of the insulating layer. The heat sink has a heat-receiving surface at its upper part that engages with the lower surface of the insulating layer and a heat-dissipating portion at its lower part. The cooling portion includes a conductive cooler that forms a flow path for the refrigerant.

[0016] Furthermore, the switch module is mounted on the cooler, ensuring that the heat dissipation part is exposed to the interior of the cooler through the insertion port, and the heat sink and the cooler are electrically insulated by a common-mode current suppression structure made of insulating components.

[0017] In other words, when the inverter is operating, it uses switching control to perform high-speed on / off switching actions in the inverter circuit. This converts direct current (DC) to alternating current (AC). During this process, the voltage in the inverter circuit changes intermittently.

[0018] The inverter circuit and the heat sink are electrically insulated from each other by an insulating layer. Like a capacitor, this structure is capable of accumulating charge (a virtual capacitor), thus generating stray capacitance. This virtual capacitor creates a current path through which common-mode current flows when the voltage changes intermittently due to switching control.

[0019] In contrast, in this inverter, the heat sink and the cooler are electrically insulated by a common-mode current suppression structure made of insulating components. Therefore, a virtual capacitor capable of generating stray capacitance is formed downstream of the aforementioned location. This prevents common-mode current from flowing directly through the cooler.

[0020] Furthermore, as described later, the common-mode current flows between the heat sink and the cooler, which are separated by insulating components, and between the heat sink and the cooler, which are separated by refrigerant. In other words, the common-mode current is distributed across current paths via multiple virtual capacitors.

[0021] As a result, the common-mode current is reduced, thereby suppressing common-mode noise. Because the insulating components are sandwiched between the heatsink and the cooler, the structure is relatively simple and easy to implement.

[0022] For example, when the switching module also includes an insulating housing cover plate covering the insulating layer, the end of the housing cover plate fits into the insertion port to form the common-mode current suppression structure.

[0023] Because only a part of the housing cover is changed, without changing the cooler, the cost is lower.

[0024] Alternatively, the cooling section may further include an insulating frame component constituting the insertion port, the frame component being mounted on the cooling section to form the common-mode current suppression structure.

[0025] In this case, existing products can be used because the switch module is not changed. It offers excellent versatility.

[0026] Alternatively, the common-mode current suppression structure may include a conductive layer embedded in the insulating component, wherein the portion of the heat sink opposite the cooler is separated by the conductive layer in an electrically insulating state, and the conductive layer is electrically connected to a constant potential portion in the electrical assembly that maintains a specified potential.

[0027] The constant potential area maintains a predetermined potential. Therefore, the potential of the conductive layer remains constant. As a result, no potential difference is generated between the conductive layer and the cooler. No charge accumulates between the conductive layer and the cooler. Consequently, common-mode current does not actually flow between the heatsink and the cooler, which are separated by insulating components.

[0028] In this way, the common-mode current flows between the heat sink and the cooler, separated by refrigerant fins. This effectively reduces common-mode noise, thus improving the speed of switching control.

[0029] The constant potential section can be a section connected to the negative side wiring of the inverter circuit, or it can be a section connected to the positive side wiring of the inverter circuit.

[0030] Furthermore, when the circuit also includes two capacitors, and the two capacitors are connected in series between the positive side wiring and the negative side wiring of the inverter circuit, the constant potential location can be the location between the two capacitors.

[0031] During the execution of switch control, each part maintains a specified potential. Therefore, as long as any of the above parts is connected, the potential of the conductive layer can remain constant.

[0032] Alternatively, when the switching module further includes an insulating housing cover plate that covers the insulating layer, and the end of the housing cover plate is fitted with the insertion port to form the common-mode current suppression structure, the conductive layer has a connection end exposed to the interior of the housing cover plate, and the conductive layer is connected to the constant potential portion through this connection end.

[0033] In this configuration, the conductive layer is located on the switch module with the constant potential portion. Furthermore, the conductive layer is embedded in the end of the housing cover. Therefore, the conductive layer and the constant potential portion can be directly connected through the interior of the housing cover. The structure is simple and easy to implement. Because the connection portion is covered by the housing cover, the protection performance is also excellent.

[0034] Alternatively, when the switch module further includes an insulating housing cover plate covering the insulating layer, and the cooling part further includes an insulating frame component constituting the insertion port, and the frame component is mounted on the cooling part to form the common mode current suppression structure, a first connection portion connected to the conductive layer is provided on the outside of the cooler, and a second connection portion connected to the constant potential portion is provided on the outside of the housing cover plate, and the first connection portion and the second connection portion are connected through a connector.

[0035] In this case, the conductive layer is provided on the cooling section where there is no constant potential. The switch module with the constant potential and the conductive layer are provided on different components. In contrast, a first connection portion connected to the conductive layer is provided on the outside of the cooler, and a second connection portion connected to the constant potential portion is provided on the outside of the housing cover. Furthermore, if the first connection portion and the second connection portion are connected by a connector, the conductive layer can also be easily connected to the constant potential portion in this case.

[0036] The refrigerant is preferably cooling oil.

[0037] Compared to cooling water, cooling oil has very low conductivity and relative permittivity. Using cooling oil as the refrigerant can effectively reduce common-mode current and suppress common-mode noise.

[0038] Alternatively, the common-mode current suppression structure may further include an insulating separator extending along the flow path of the refrigerant to separate the heat dissipation portion from the portion of the cooler opposite to it across the refrigerant. A second conductive layer connected to the conductive layer is embedded in the separator.

[0039] Therefore, the potential of the second conductive layer remains constant. As a result, no potential difference is generated between the second conductive layer and the cooler. No charge accumulates between the second conductive layer and the cooler. Consequently, common-mode current does not actually flow between the heat sink and the cooler, which are separated by refrigerant.

[0040] In this way, common-mode current essentially stops flowing. This minimizes common-mode noise, thereby increasing the speed of switching control.

[0041] In the above circumstances, the refrigerant can also be cooling water.

[0042] Since the common-mode current does not actually flow between the heat dissipation section and the cooler separated by the refrigerant, using cooling water as the refrigerant is not a problem. Cooling water is easy to handle and has excellent versatility.

[0043] -The effects of the invention-

[0044] Inverters employing the techniques disclosed herein can effectively suppress common-mode noise with a relatively simple structure. Therefore, they are easy to implement and can improve inverter performance at a low cost. Attached Figure Description

[0045] Figure 1 This is a simplified diagram of an inverter based on the technology disclosed herein;

[0046] Figure 2 This is a simplified diagram (top view) showing the unmodified module (comparative example);

[0047] Figure 3 It is along Figure 2 A simplified sectional view taken along line Y1-Y1 with the arrowhead in the middle;

[0048] Figure 4 It is along Figure 2 A simplified sectional view taken along line Y2-Y2 with the arrowhead in the middle;

[0049] Figure 5 It is a circuit diagram of an unmodified inverter equipped with an unmodified module;

[0050] Figure 6 It is shown that... Figure 4 A simplified diagram of the corresponding improved module (example);

[0051] Figure 7 This is a circuit diagram of an improved inverter equipped with an improved module;

[0052] Figure 8 This is a diagram used to illustrate a modified example of an improved inverter;

[0053] Figure 9 This is a diagram illustrating an application example of an improved inverter (first application inverter), showing the first application module (top view);

[0054] Figure 10 It is along Figure 9 A simplified sectional view taken along line Y3-Y3 with the arrow in the middle;

[0055] Figure 11 This is the circuit diagram of the first application inverter;

[0056] Figure 12 This is a diagram used to illustrate a variation of a constant potential region;

[0057] Figure 13 This is a diagram used to illustrate a variation of a constant potential region;

[0058] Figure 14 This is a diagram used to illustrate a variation of the first application inverter;

[0059] Figure 15 It is the second application inverter and Figure 10 Corresponding simplified diagram;

[0060] Figure 16 This is the circuit diagram of the second application inverter;

[0061] Figure 17 This is a diagram used to illustrate a variation of the second application inverter.

[0062] - Symbol Explanation -

[0063] 1 – Inverter; 1a – Electrical assembly; 1b – Cooling assembly; 5 – Switching module; 10 – Cooler; 10a – Insertion port; 20 – Improved module (switching module); 21 – Common-mode current suppression structure; 22 – Fitting part; 30 – Improved inverter (inverter using the technology disclosed herein); 31 – First application inverter; 31a – First application module; 32 – Second application inverter; 32a – Second application module; 41 – Frame component; 50 – Conductive layer; 50a – Connection end; 52 – Capacitor; 55 – First connection part; 56 – Second connection part; 57 – Connector; 60 – Separator component; 61 – Second conductive layer; 100 – Unimproved module; 101 – Substrate (insulating layer); 102 – Heat sink; 102a – Heated surface part; 102c – Heat dissipation 102d - Heat sink; 103 - Housing cover; 104 - Electronic circuit; 104a - Inverter circuit; 104b - Half-bridge circuit; 105 - Switching element; 105U - Upper arm chip; 105L - Lower arm chip; 105a - Collector; 105b - Emitter; 105c - Base; 106 - Electrode conductor; 106a - Positive side wiring terminal; 106b - Negative side wiring terminal; 106c - Output wiring terminal; 106d - Switching terminal; 120 - Unmodified inverter; 121 - High-voltage battery; 122 - Drive motor; 123H - Positive side wiring; 123L - Negative side wiring; 124 - Output wiring; 125 - Smoothing capacitor; 126 - Control circuit; C1~C8 - Virtual capacitors. Detailed Implementation

[0064] The technology disclosed herein will now be described. However, the following description is merely an example in essence. The up and down directions used in the description are examples of relative directions and are not necessarily up and down.

[0065] <Inverter>

[0066] Figure 1 An inverter 1, which is based on the technology disclosed herein, is shown in simplified form. The inverter 1 includes an electrical assembly section 1a that houses electronic components and a cooling section 1b that cools the electronic components that heat up during operation. The electrical assembly section 1a and the cooling section 1b are integrated into one unit.

[0067] The cooling section 1b has a refrigerant inlet and a refrigerant outlet. The cooling section 1b is connected to the cooling device 2 and the refrigerant circulation path 3, which are separate from the inverter 1, via the refrigerant inlet and refrigerant outlet. When the inverter 1 is operating, the refrigerant cooled by the cooling device 2 is circulated and supplied to the cooling section 1b via the refrigerant circulation path 3.

[0068] The electrical assembly section 1a houses various electronic components constituting the inverter 1, such as the control circuit 126 and the smoothing capacitor 125, which will be described later. The technology disclosed herein focuses on the portion of the aforementioned electronic components related to the switching module 5 constituting the inverter circuit 104a.

[0069] (Unmodified module)

[0070] To facilitate understanding of the technology disclosed herein, a comparative example will be described using a switch module 5 (unmodified module 100) prior to the application of the technology disclosed herein.

[0071] Figure 2 A simplified diagram of the interior of the unmodified module 100 as seen from above is shown. Figure 3 Showing from Figure 2 A simplified diagram observed along the direction indicated by the arrowed line Y1-Y1. Figure 4 Show along Figure 2 A simplified sectional view taken along line Y2-Y2 with an arrow in the center.

[0072] like Figures 2-4 As shown, the unmodified module 100 includes a substrate 101 (an example of an insulating layer) and a heat sink 102 bonded to the lower surface of the substrate 101. The substrate 101 may be an insulating plate formed of a ceramic sintering material.

[0073] The unmodified module 100 also includes a plastic (insulating) housing cover 103 covering the substrate 101. The housing cover 103 has a rectangular side frame portion 103a when viewed from above and a cover portion 103b that closes the opening on the upper side of the side frame portion 103a. A fitting recess 103c for mounting is formed at the lower edge of the opening on the side frame portion 103a opposite to the cover portion 103b.

[0074] The interior of the housing cover 103 is filled with insulating resin, not shown.

[0075] The heat sink 102 is made of aluminum alloy that appears rectangular when viewed from above. However, the material of the heat sink 102 is not limited to aluminum alloy; any material with excellent thermal conductivity and electrical conductivity is acceptable. A flat heat-receiving surface 102a is provided on the upper part of the heat sink 102.

[0076] Around the heated surface 102a, a frame-shaped fitting protrusion 102b is provided, which fits into the fitting recess 103c of the housing cover 103. The side frame portion 103a of the housing cover 103 is fixed to the heat sink 102 by the fitting of the fitting recess 103c and the fitting protrusion 102b. At the lower part of the heat sink 102, a heat dissipation portion 102d is provided, which is composed of a plurality of pin-shaped heat dissipation protrusions 102c.

[0077] A flange 102e extends around the heat sink 102. At the four corners of the flange 102e, fastening portions 102f for fixing pins are provided.

[0078] like Figure 3 , Figure 4 As shown, the cooling section 1b includes a cooler 10. Like the heat sink 102, the cooler 10 is made of aluminum alloy.

[0079] A refrigerant flow path 11 is formed inside the cooler 10, and the refrigerant flows along... Figure 4 The refrigerant flows in the direction indicated by the middle arrow F. A rectangular inlet 10a, communicating with the refrigerant flow path 11, is formed at the upper part of the cooler 10.

[0080] The heat sink 102 is inserted into the insertion port 10a, ensuring that the heat dissipation part 102d is exposed to the interior of the cooler 10 through the insertion port 10a. The area around the insertion port 10a is sealed to prevent liquid leakage. In this way, the heat sink 102 is installed onto the cooler 10 by pinning each fastening part 102f.

[0081] An electronic circuit 104, including an inverter circuit 104a, is provided on the upper surface of the substrate 101. Specifically, the inverter circuit 104a includes three half-bridge circuits 104b consisting of two switching elements 105 (a semiconductor chip, an upper arm chip 105U, and a lower arm chip 105L) connected in series. The half-bridge circuits 104b correspond to the U-phase, V-phase, and W-phase outputs of the inverter 1, respectively.

[0082] The switching element 105 here is an insulated gate bipolar transistor. Figure 4 In the diagram, "C" represents collector 105a (first electrode), "E" represents emitter 105b (second electrode), and "B" represents base 105c (third electrode). It should be noted that each switching element 105 is related to the freewheeling diode (…). Figure 5 (Refer to the anti-parallel connection; diagram omitted here.)

[0083] An electrode conductor 106 of a predetermined shape is formed on the upper surface of the substrate 101. Using the electrode conductor 106, an electronic circuit 104 corresponding to the electrical wiring of the inverter circuit 104a is provided.

[0084] Specifically, such as Figure 2 As shown, the electrode conductor 106 has a positive electrode side wiring terminal portion 106a that constitutes the positive electrode side wiring 123H, a negative electrode side wiring terminal portion 106b that constitutes the negative electrode side wiring 123L, three output wiring terminal portions 106c that constitute the output wiring 124 corresponding to U, V, and W respectively, and six switching terminal portions 106d that constitute switching terminals connected to the base 105c of each semiconductor chip.

[0085] Emitter 105b and base 105c are disposed on the upper surface of switching element 105. The area of ​​emitter 105b is larger than the area of ​​base 105c used for control.

[0086] Each upper arm chip 105U is soldered to a designated position on the positive side wiring terminal 106a using soldering. In this way, the collector 105a of each upper arm chip 105U is connected to the positive side wiring 123H.

[0087] The emitter 105b of each upper arm chip 105U is connected to the corresponding output wiring terminal 106c via bonding wire 107a. In this way, the emitter 105b of each upper arm chip 105U is connected to the output wiring 124. The base 105c of each upper arm chip 105U is connected to the corresponding switching terminal 106d via bonding wire 107b.

[0088] Each lower arm chip 105L is soldered to a designated position on the output wiring terminal 106c of each phase. In this way, the collector 105a of each lower arm chip 105L is connected to the output wiring 124 of each phase.

[0089] The emitter 105b of each lower arm chip 105L is connected to the negative side wiring terminal 106b via bonding wire 107c. The base 105c of each lower arm chip 105L is connected to each switching terminal 106d via bonding wire 107d. Each switching terminal 106d is provided for switching the conduction and disconnection of the current path between the collector 105a and the emitter 105b.

[0090] Between the output wiring terminal 106c (especially the junction of the collector 105a of each lower arm chip 105L) and the heat sink 102, a structure capable of accumulating charge is formed, namely, a structure in which two electrical conductors are positioned opposite each other separated by an insulating material (dielectric). Furthermore, the voltage of the output wiring terminal 106c changes intermittently by switching control. In this way, a predetermined stray capacitance can be generated at this location (in the description, for convenience, it is assumed that a virtual capacitor C is formed at the location where stray capacitance can be generated).

[0091] Therefore, as Figure 4 As shown in the magnified view, a virtual capacitor C (first virtual capacitor C1) is formed at this location, capable of generating a specified stray capacitance.

[0092] Figure 5 An example of the configuration of an on-board inverter 1 (unmodified inverter 120) equipped with an unmodified module 100 is shown. The unmodified inverter 120 is located between a high-voltage battery 121 for driving and a drive motor 122 (an AC motor, generally a permanent magnet synchronous motor) for travel. The unmodified inverter 120 has the aforementioned positive-side wiring 123H, negative-side wiring 123L, and output wiring 124. The positive-side wiring 123H is connected to the positive terminal of the high-voltage battery 121, and the negative-side wiring 123L is connected to the negative terminal of the high-voltage battery 121.

[0093] Three half-bridge circuits 104b are connected in parallel between the positive side wiring 123H and the negative side wiring 123L on the output side of the unmodified inverter 120. A smoothing capacitor 125 is installed between the positive side wiring 123H and the negative side wiring 123L on the input side of the unmodified inverter 120.

[0094] The unmodified inverter 120 includes a control circuit 126 for switching control. The control circuit 126 is connected to the base 105c of each switching element 105 of the unmodified module 100. The unmodified inverter 120 turns each switching element 105 on or off at a specified operating frequency (e.g., 10 kHz) and converts the DC power supplied by the high-voltage battery 121 into a three-phase AC power consisting of U, V, and W, which is then supplied to the drive motor 122.

[0095] The heat sink 102 is grounded by connecting to the metal part of the vehicle body via the cooler 10. Therefore, as described above, a first virtual capacitor C1 is formed between the output wiring terminal 106c (especially the junction of the collector 105a of the lower arm chip 105L of each phase) and the heat sink 102. Because the high-voltage battery 121 is in a floating state, a virtual capacitor C (second virtual capacitor C2) with a specified stray capacitance exists between the high-voltage battery 121 and ground.

[0096] When the unmodified inverter 120 is operating, a square wave high voltage, including high-order harmonic components, is applied between (at the midpoint) the upper arm chip 105U and the lower arm chip 105L in each half-bridge circuit 104b. Thus, as... Figure 5 As indicated by the middle arrow Ic, the common-mode current flows through the current path via the first virtual capacitor C1 and the second virtual capacitor C2. This generates common-mode noise.

[0097] The high-voltage battery 121 has a rated voltage of high voltage, such as above 40V or 100V. Therefore, in this case, due to the large voltage variation, the common-mode current and common-mode noise are also large. As a result, the improvement of switching control speed is limited due to the presence of common-mode noise.

[0098] (Improved module, improved inverter 1)

[0099] Figure 6 An example of a switch module 5 (modified module 20) that applies the technology disclosed herein is shown. Figure 6 Is with Figure 4 The corresponding diagram. Top view of improved module 20 and... Figure 2 The same, therefore its illustration is omitted (from) Figure 2 The same applies to the diagram observed along the direction indicated by the arrowed line Y1-Y1. Figure 7 An example of an on-board inverter 1 (improved inverter 30) equipped with the improved module 20 is shown.

[0100] The basic structure of the improved module 20 is the same as that of the unimproved module 100. The basic structure of the improved inverter 30 is also the same as... Figure 5The unmodified inverter 120 shown is identical. Therefore, the same symbols are used to mark components with the same content, and their descriptions are simplified or omitted (the same applies to the following variations, application examples, etc.).

[0101] The difference between the improved module 20 and the unimproved module 100 is that the heat sink 102 and the cooler 10 are sandwiched together by a prescribed structure (common mode current suppression structure 21) made of insulating components for electrical insulation.

[0102] Specifically, such as Figure 6 As shown, in the improved module 20, the lower side of the side frame portion 103a of the housing cover plate 103 extends out to form a fitting portion 22 that fits into the insertion port 10a. The heat sink 102 is embedded inside the fitting portion 22 and fixed to the housing cover plate 103.

[0103] In the improved inverter 30, the end of the housing cover plate 103, namely the fitting portion 22, fits into the insertion port 10a to form a common-mode current suppression structure 21. That is, in the improved inverter 30, the heat sink 102 and the cooler 10 are electrically insulated from each other by the fitting portion 22.

[0104] In this way, such as Figure 6 As shown in the enlarged view, in the improved module 20, in addition to the first virtual capacitor C1 mentioned above, virtual capacitors C (third virtual capacitor C3 and fourth virtual capacitor C4) capable of generating a specified stray capacitance are formed at various locations between the outer periphery of the heat sink 102 facing each other and the inner periphery of the insertion port 10a, and between the heat dissipation portion 102d (more specifically, the protruding end of each heat dissipation protrusion 102c) of the heat sink 102 facing each other across the refrigerant and the inner surface of the cooler 10.

[0105] In this way, such as Figure 7 As shown, the first virtual capacitor C1 is connected in series with the third virtual capacitor C3 and the fourth virtual capacitor C4 respectively.

[0106] In this case, the stray capacitance that can be generated by the first virtual capacitor C1, the third virtual capacitor C3, and the fourth virtual capacitor C4 is less than the stray capacitance that can be generated by the first virtual capacitor C1 of the unmodified module 100.

[0107] Therefore, the common-mode current is reduced, thereby suppressing common-mode noise.

[0108] It should be noted that the dielectric of the fourth virtual capacitor C4 is composed of refrigerant. Generally, cooling water is often used as the refrigerant. However, cooling water has relatively high conductivity and relative permittivity. Therefore, when cooling water is used as the refrigerant, the stray capacitance of the fourth virtual capacitor C4 is relatively large, and the suppression effect of common-mode current is weak.

[0109] Therefore, cooling oil (transformer cooling oil, working oil, etc.) is preferred as the refrigerant. Compared to cooling water, cooling oil has a very low conductivity and relative permittivity. Using cooling oil as the refrigerant can effectively reduce common-mode current and suppress common-mode noise.

[0110] (Example of a modified inverter)

[0111] Figure 8 A modified example of the improved inverter 30 is shown. In the improved inverter 30, a common-mode current suppression structure 21 is formed by changing the structure of the switching module 5.

[0112] In contrast, in this modified example, a common-mode current suppression structure 21 is formed by changing the structure of the cooler 10. Therefore, in this modified example, the existing switch module 5 (unmodified module 100) can be used. It should be noted that the basic structure of this modified example is the same as that of the modified inverter 30.

[0113] like Figure 8 As shown, in this modified example, the cooling section 1b further includes a plastic (insulating) frame member 41 that forms the insertion port 10a. The insertion port 10a is formed on the inner side of the frame member 41. The frame member 41 is sealed to prevent liquid leakage and is mounted on the cooler 10 in this state.

[0114] In this modified example, the heat sink 102 is electrically insulated from the cooler 10 by the frame member 41.

[0115] Therefore, this modified example can also achieve the same function and effect as the improved inverter 30.

[0116] <Application Examples of Improved Inverters>

[0117] (First application: Inverter)

[0118] Figures 9-11 An application example of the improved inverter 30 is shown (first application inverter 31). Figure 9 This is a simplified diagram of the interior of its switch module 5 (first application module 31a) as viewed from above. Figure 10 It is along Figure 9 A simplified sectional view taken along line Y3-Y3 with the arrow in the middle. Figure 11 This is a simplified diagram showing the configuration of the first application inverter 31.

[0119] The difference between the first application module 31a and the improved module 20 is that a specified conductive layer 50 is provided on the common-mode current suppression structure 21.

[0120] Specifically, such as Figure 9 , Figure 10As shown, a frame-shaped conductive layer 50 extending around the heat sink 102 is embedded in the fitting portion 22 that constitutes the common-mode current suppression structure 21. The conductive layer 50 can be formed, for example, from a copper plate or copper foil. The conductive layer 50 is insulated by being covered with plastic.

[0121] In this way, the portions of the heat sink 102 and the cooler 10 opposite each other are separated by the conductive layer 50 in an electrically insulated state. Thus, as... Figure 10 As shown in the magnified image, the third virtual capacitor C3 is divided into two virtual capacitors C connected in series.

[0122] That is, it is divided into a fifth virtual capacitor C5 formed between the heat sink 102 and the conductive layer 50 and a sixth virtual capacitor C6 formed between the conductive layer 50 and the cooler 10.

[0123] And, as Figure 9 , Figure 10 As shown, the conductive layer 50 has a connecting end 50a protruding into the interior of the housing cover plate 103. The conductive layer 50 is electrically connected to the negative electrode side wiring terminal portion 106b through this connecting end 50a.

[0124] The negative-side wiring terminal 106b is the location of the negative-side wiring 123L in the inverter circuit 104a. For example... Figure 11 As shown in the simplified diagram, the conductive layer 50 is connected to the negative electrode side wiring 123L via the connection end 50a.

[0125] Therefore, the potential of the conductive layer 50 is the same as the potential of the negative terminal of the high-voltage battery 121. Even if the switching element 105 of the lower arm chip 105L is turned on or off by switching control, the fifth virtual capacitor C5 will charge and discharge accordingly, so no potential difference will be generated between the heat sink 102 and the conductive layer 50. No charge will accumulate in the sixth virtual capacitor C6.

[0126] In this way, common-mode current will not flow through the current path via the fifth virtual capacitor C5 and the sixth virtual capacitor C6. Common-mode current flows through the current path via the first virtual capacitor C1 and the fourth virtual capacitor C4 connected in series. The stray capacitance generated by the first virtual capacitor C1 and the fourth virtual capacitor C4 connected in series is smaller than the stray capacitance that can be generated in the improved inverter 30.

[0127] Therefore, the common-mode current is further reduced, thereby further suppressing common-mode noise.

[0128] (Location with constant potential)

[0129] In the first application module 31a described above, the portion of the negative side wiring 123L, specifically the negative side wiring terminal portion 106b of each phase (the emitter 105b of the lower arm chip 105L of each phase), is defined as a "constant potential portion". However, the constant potential portion is not limited to the portion of the negative side wiring 123L, as long as the potential of the portion connected to the conductive layer 50 does not change during switching control.

[0130] Therefore, as Figure 12 As shown, the conductive layer 50 may also not be connected to the negative-side wiring terminal portion 106b, but to the high-voltage wiring portion, i.e., the positive-side wiring terminal portion 106a of each phase (the collector 105a of the upper arm of the chip 105U of each phase) (see reference). Figure 12 The first wiring 51 in the middle). That is to say, the part of the positive side wiring 123H can also be defined as the "constant potential part".

[0131] In this configuration, regardless of whether the circuit is on or off, the conductive layer 50 maintains the potential of the positive terminal side of the high-voltage battery 121. Thus, no potential difference is generated between the heat sink 102 and the conductive layer 50, regardless of whether the circuit is on or off. No charge accumulates in the sixth virtual capacitor C6 due to the charging and discharging of the fifth virtual capacitor C5. Therefore, common-mode current does not flow through the current path via the fifth virtual capacitor C5 and the sixth virtual capacitor C6.

[0132] Moreover, such as Figure 13 As shown, this can also be utilized when the inverter 1, which is the object, includes two capacitors 52, 52, and the two capacitors 52, 52 are connected in series between the positive side wiring 123H and the negative side wiring 123L. That is, the portion between the two capacitors 52, 52 maintains a specified voltage value that is lower than the voltage of the high-voltage battery 121.

[0133] Therefore, the portion between the two capacitors 52, 52 can also be defined as the "constant potential portion", and the conductive layer 50 can be connected to this portion (see reference). Figure 13 The second wiring (53) in the middle.

[0134] In this condition, regardless of whether the circuit is on or off, the conductive layer 50 maintains a predetermined potential lower than the voltage of the high-voltage battery 121. Therefore, no potential difference is generated between the conductive layer 50 and the heat sink 102. No charge accumulates in the sixth virtual capacitor C6 due to the charging and discharging of the fifth virtual capacitor C5. Consequently, common-mode current does not flow through the current path via the fifth virtual capacitor C5 and the sixth virtual capacitor C6.

[0135] (A variation of the first application inverter)

[0136] Figure 14A modified example of the first application inverter 31 is shown. In this modified example, similar to the second improved inverter 30 described above, a common-mode current suppression structure 21 is formed by changing the structure of the cooler 10. Therefore, in this modified example, the existing switching module 5 (unmodified module 100) can be used with only a partial change.

[0137] In this modified example, a conductive layer 50 is provided on the frame member 41 of the cooler 10. Therefore, it cannot be directly connected to the constant potential part within the switch module 5. In contrast, in this modified example, a first connection portion 55 connected to the conductive layer 50 is provided on the outside of the cooler 10.

[0138] Correspondingly, a second connection portion 56 is provided on the outside of the housing cover plate 103, which is connected to the negative side wiring terminal portion 106b (an example of a constant potential portion). Furthermore, the aforementioned first connection portion 55 and the second connection portion 56 are connected via a connector 57.

[0139] Therefore, under these circumstances, the same function and effect as the first application inverter 31 can be obtained.

[0140] (Second application inverter)

[0141] Figure 15 , Figure 16 An application example of the first application inverter 31 (second application inverter 32) is shown. Figure 15 Is with Figure 10 The corresponding simplified sectional view. That is to say, Figure 15 The switching module 5 (second application module 32a) of the second application inverter 32 is shown. Figure 16 This is a simplified diagram showing the configuration of the second application inverter 32.

[0142] The difference between the second application inverter 32 and the first application inverter 31 is that the common-mode current suppression structure 21 also includes a separation component 60.

[0143] Specifically, an insulating partition member 60 is provided on the housing cover plate 103 to surround the heat dissipation portion 102d of the heat sink 102. On the lower side of the fitting portion 22 of the housing cover plate 103, a new cylindrical portion extending along the refrigerant flow path 11 is provided to form the partition member 60.

[0144] Therefore, the material of the partition member 60 is the same plastic as that of the housing cover plate 103. The partition member 60 has a U-shaped cross section and is configured to separate the heat dissipation part 102d from the part of the cooler 10 that is opposite to it through the refrigerant.

[0145] A second conductive layer 61, composed of copper plates, copper foils, etc., is embedded in the separator 60. The second conductive layer 61 is surrounded by plastic and is insulated from the refrigerant.

[0146] In this way, with the refrigerant sandwiched between the heat dissipation section 102d (more specifically, the protruding ends of each heat dissipation protrusion 102c) and the portion opposite the inner surface of the cooler 10 are separated by the conductive layer 50 in an electrically insulating state. Thus, as... Figure 15 As shown in the enlarged image, Figure 10 The fourth virtual capacitor C4 shown is divided into two virtual capacitors C connected in series.

[0147] That is, it is divided into a seventh virtual capacitor C7 formed between the heat dissipation part 102d and the second conductive layer 61 and an eighth virtual capacitor C8 formed between the second conductive layer 61 and the inner surface of the cooler 10.

[0148] And, as Figure 15 As shown, the second conductive layer 61 is integrally formed with the conductive layer 50 through a pair of edges on its upper side and is electrically connected to the conductive layer 50. The conductive layer 50 and the second conductive layer 61 are connected to the negative electrode side wiring 123L through the connection end 50a.

[0149] Therefore, the potentials of conductive layer 50 and the second conductive layer 61 are the same as the potential of the negative terminal of the high-voltage battery 121. Even if the switching element 105 of the lower arm chip 105L is turned on or off by switching control, the seventh virtual capacitor C7 will charge and discharge accordingly, so no potential difference will be generated between the portion of the second conductive layer 61 opposite to the inner surface of the cooler 10. No charge will accumulate in the eighth virtual capacitor C8.

[0150] Therefore, as Figure 16 As shown in the simplified diagram, the common-mode current does not flow through the current path via the fifth virtual capacitor C5 and the sixth virtual capacitor C6, nor does it flow through the current path via the seventh virtual capacitor C7 and the eighth virtual capacitor C8.

[0151] There is no current path available for common-mode current to flow. Therefore, it is possible to prevent the generation of common-mode noise. In other words, it is not about reducing the common-mode current, but about making the common-mode current virtually zero.

[0152] In this case, common-mode current will not flow through the current path via the seventh virtual capacitor C7 and the eighth virtual capacitor C8, which include the refrigerant as the dielectric. Therefore, the refrigerant is not limited to cooling oil; cooling water can also be used. This increases the freedom of choice in refrigerant selection and provides greater convenience.

[0153] (A variation of the second application inverter)

[0154] Figure 17A modified example of the second application inverter 32 is shown. In this modified example, similar to the modified example of the first application inverter 31 described above, the common-mode current suppression structure 21 is formed by changing the structure of the cooler 10. Therefore, in this modified example, the existing switching module 5 (unmodified module 100) can be used with only a partial change.

[0155] In this modified example, a conductive layer 50 is provided on the frame member 41 of the cooler 10. Therefore, in this modified example, a first connection portion 55 connected to the conductive layer 50 is provided on the outside of the cooler 10. Correspondingly, a second connection portion 56 connected to the negative electrode side wiring terminal portion 106b (an example of a constant potential portion) is provided on the outside of the housing cover plate 103. Furthermore, the first connection portion 55 and the second connection portion 56 are connected by a connector 57.

[0156] Therefore, in this case, the same function and effect as the second application inverter 32 can be obtained.

[0157] It should be noted that the technology disclosed herein is not limited to the embodiments described above, but also includes various other configurations. For example, the features shown in the above-described variations and application examples are not limited to these embodiments. They can also be applied to other embodiments as needed.

[0158] Switching elements can be made from known semiconductor chips such as MOSFETs, bipolar transistors, insulated gate bipolar transistors, and GaN.

Claims

1. An inverter comprising an electrical assembly section and a cooling section integrated into one unit, wherein the electrical assembly section houses electronic components including a switching module, characterized in that: The switching module includes an insulating layer and a heat sink. An electronic circuit, including an inverter circuit, is provided on the upper surface of the insulating layer. The heat sink has a heat-receiving surface at the top that engages with the lower surface of the insulating layer, and a heat-dissipating surface at the bottom. The cooling section includes a conductive cooler that forms part of the refrigerant flow path. The switch module is installed on the cooler, ensuring that the heat dissipation part is exposed to the interior of the cooler through the insertion port. The heat sink and the cooler are electrically insulated from each other by a common-mode current suppression structure made of insulating components. The switch module also includes an insulating housing cover plate that covers the insulating layer. The end of the housing cover plate fits into the insertion port to form the common-mode current suppression structure.

2. The inverter according to claim 1, characterized in that: The common-mode current suppression structure includes a conductive layer embedded in the insulating component. The portion of the heat sink opposite the cooler is separated by the conductive layer in an electrically insulating state, and the conductive layer is electrically connected to the constant potential portion of the electrical assembly that maintains a specified potential.

3. The inverter according to claim 2, characterized in that: The constant potential section is the section connected to the negative side wiring of the inverter circuit.

4. The inverter according to claim 2, characterized in that: The constant potential section is the section connected to the positive side wiring of the inverter circuit.

5. The inverter according to claim 2, characterized in that: The inverter also includes two capacitors, which are connected in series between the positive-side wiring and the negative-side wiring of the inverter circuit. The constant potential region is the region between the two capacitors.

6. The inverter according to claim 2, characterized in that: The conductive layer has a connection end that protrudes into the interior of the housing cover, and the conductive layer is connected to the constant potential portion through this connection end.

7. The inverter according to any one of claims 1 to 6, characterized in that: The refrigerant used is cooling oil.

8. The inverter according to any one of claims 2 to 6, characterized in that: The common-mode current suppression structure further includes an insulating separator extending along the refrigerant flow path to separate the heat dissipation section from the portion of the cooler opposite to it across the refrigerant. The separator is embedded with a second conductive layer that is connected to the conductive layer.

9. The inverter according to claim 8, characterized in that: The refrigerant used is cooling water.

10. An inverter comprising an electrical assembly section and a cooling section integrated into one unit, wherein the electrical assembly section houses electronic components including a switching module, characterized in that: The switching module includes an insulating layer and a heat sink. An electronic circuit, including an inverter circuit, is provided on the upper surface of the insulating layer. The heat sink has a heat-receiving surface at the top that engages with the lower surface of the insulating layer, and a heat-dissipating surface at the bottom. The cooling section includes a conductive cooler that forms part of the refrigerant flow path. The switch module is installed on the cooler, ensuring that the heat dissipation part is exposed to the interior of the cooler through the insertion port. The heat sink and the cooler are electrically insulated from each other by a common-mode current suppression structure made of insulating components. The cooling section also includes an insulating frame component that forms the insertion port. The frame component is mounted on the cooling section to form the common-mode current suppression structure.

11. The inverter according to claim 10, characterized in that: The common-mode current suppression structure includes a conductive layer embedded in the insulating component. The portion of the heat sink opposite the cooler is separated by the conductive layer in an electrically insulated state, and the conductive layer is electrically connected to the constant potential portion in the electrical assembly that maintains a specified potential.

12. The inverter according to claim 11, characterized in that: The switch module also includes an insulating housing cover plate that covers the insulating layer. The cooling section also includes an insulating frame component that forms the insertion port. The frame component is mounted on the cooling section to form the common-mode current suppression structure. A first connection portion connected to the conductive layer is provided on the outside of the cooler, and a second connection portion connected to the constant potential portion is provided on the outside of the housing cover plate. The first connection portion and the second connection portion are connected by a connector.

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