T-type neutral point clamped power module with dual-sided cooling package

Abstract

This invention relates to a T-type neutral point clamping power module with a dual-sided cooling package. The power module includes a positive DC terminal (DCP), a negative DC terminal (DCN), a neutral terminal (N), and an AC terminal. The positive DC terminal (DCP) is connected to the AC terminal via a first switching element (S1). The neutral terminal (N) is connected to the AC terminal via a third switching element (S3) and a second switching element (S2). The negative DC terminal (DCN) is connected to the AC terminal via a fourth switching element (S4). The power module also includes a top substrate (311) and a bottom substrate (312) facing the top substrate (311). At least one of the switching elements (S1, S2, S3, S4) is fixed to the top substrate (311), and at least one of the switching elements (S1, S2, S3, S4) is fixed to the bottom substrate (312).

Description

Technical Field

[0001] This disclosure relates to a power supply module. Background Technology

[0002] A T-type inverter is a three-level inverter, meaning it can produce three different voltage levels at its output: positive, zero, and negative. The main components of a T-type inverter include switches (IGBTs or MOSFETs) for controlling current flow, diodes that provide a path for current when the switches are open, and capacitors for stabilizing the voltage levels.

[0003] In operation, when the top switch (S1) is on and the middle switch (S2) is off, the T-type inverter generates a positive output voltage, connecting the output to the positive DC bus. When the middle switch (S2) is on, zero output voltage is achieved, connecting the output to the neutral point. When the bottom switch (S3) is on and the middle switch (S2) is off, a negative output voltage occurs, connecting the output to the negative DC bus. Controlling the switches in a specific sequence to generate the desired output waveform ensures that the voltage stress on each switch is only half that of the DC bus voltage, a significant advantage over conventional two-level inverters.

[0004] T-type inverters offer several advantages, including reduced voltage stress on each switch, improved efficiency due to lower switching losses and better thermal management, and better output quality with cleaner waveforms and lower harmonic distortion. These inverters are commonly used in renewable energy systems such as solar inverters, motor drives for industrial and electric vehicle applications, and uninterruptible power supplies (UPS) to ensure a stable power supply. However, T-type inverters are not limited to these applications.

[0005] 3L-TNPC (Three-Level T-Type Neutral-Clamped) inverters are known for their efficiency, relatively low total harmonic distortion (THD), and relatively low common-mode noise in electrification advancement applications. These 3L-TNPCs are known to include wide-bandgap (WBG) devices. However, the benefits of these devices are limited by their switching speed and overheating. The introduction of an additional neutral branch complicates the commutation circuit. An unbalanced commutation circuit can lead to undesirable stray inductance.

[0006] The background section is intended only to provide a contextual overview of some current problems and is not intended to be exhaustive. Further contextual information will become apparent to those skilled in the art after reading the following detailed description. Summary of the Invention

[0007] According to one aspect, a power module may be provided, comprising:

[0008] Positive DC terminal, negative DC terminal, neutral terminal, and AC terminal, among which

[0009] The positive DC terminal is connected to the AC terminal via a first switching element.

[0010] The neutral terminal is connected to the AC terminal via a third switching element and a second switching element, and

[0011] The negative DC terminal is connected to the AC terminal via a fourth switching element;

[0012] The power module further includes a top substrate and a bottom substrate facing the top substrate, wherein at least one of the switching elements is fixed to the top substrate and at least one of the switching elements is fixed to the bottom substrate.

[0013] The separate top and bottom substrates allow for parallel cooling of each side, enabling the assembly to be more effectively maintained within the desired temperature range. Furthermore, by attaching at least one switching element to the top substrate and at least one switching element to the bottom substrate, the heat dissipation of the switches is distributed across the two substrates, allowing them to be cooled more efficiently.

[0014] The inventors have recognized that planar concepts (components in a planar layout) can be optimized to reduce stray inductance or thermal resistance. It is difficult to reduce both simultaneously with a planar solution. This invention proposes a vertical solution forming a three-dimensional layout where components are distributed across multiple substrates, which allows for reduction of stray inductance and thermal resistance.

[0015] The power module may also include a top secondary substrate fixed to a top substrate and a bottom secondary substrate fixed to a bottom substrate, wherein the top secondary substrate and the bottom secondary substrate are located between the top substrate and the bottom substrate. This facilitates the provision of a conductive layer between the respective substrates and secondary substrates.

[0016] The second switching element can be fixed to the top secondary substrate, which is located between the top substrate and the second switching element. Therefore, the conductive layer can pass between the top substrate and the top secondary substrate without contacting the second switching element.

[0017] Similarly, the third switching element can be fixed to the bottom secondary substrate, which is located between the third switching element and the bottom substrate. In this way, the conductive layer can pass between the bottom substrate and the top secondary substrate without contacting the third switching element.

[0018] The top and bottom substrates can each include two conductive surfaces with an electrically insulating layer between them, and the top and bottom secondary substrates can also each include two conductive surfaces with an electrically insulating layer between them. Thus, the conductive layer between the substrates can be formed from the conductive surfaces of the substrates. Externally, the conductive surfaces of the primary and secondary substrates can also provide thermal conductivity. Furthermore, internally, the conductive surfaces can be used for electrically connecting components such as switches fixed to the substrates. Electrical paths can be engraved in the conductive surfaces.

[0019] The second switching element can be fixed to the top secondary substrate, which is located between the second switching element and the top substrate, and the third switching element can be fixed to the bottom secondary substrate, which is located between the third switching element and the bottom substrate. In this way, heat dissipation is divided on the substrates on both sides of the power module. Furthermore, separate conductive paths are generated that pass along these switching elements without electrically connecting to them.

[0020] The power module may further include a first supporting conductive element connecting the top substrate to the bottom substrate and / or a second supporting conductive element connecting the top secondary substrate to the bottom secondary substrate. Such supporting conductive elements provide sufficient volume within the power module to prevent collapse, while providing electrical connections between the opposing conductive surfaces of the top and bottom substrates or between the opposing conductive surfaces of the top and bottom secondary substrates.

[0021] The drain side of the first switching element can be fixed to the conductive surface of the top substrate, the drain side of the second switching element can be fixed to the conductive surface of the top secondary substrate, the drain side of the third switching element can be fixed to the conductive surface of the bottom secondary substrate, and the drain side of the fourth switching element can be fixed to the conductive surface of the bottom substrate. "Fixed" means fixedly attached and also electrically connected. This allows for the provision of desired current flow while simultaneously providing desired heat dissipation to the substrate.

[0022] The source of the first switching element can be conductively connected to a conductive surface of the top substrate, the source of the second switching element can be conductively connected to a conductive surface of the top secondary substrate, the source of the third switching element can be conductively connected to a conductive surface of the bottom secondary substrate, and the source of the fourth switching element can be conductively connected to a conductive surface of the bottom substrate. Furthermore, the corresponding conductive surfaces can be interrupted between their respective drain sides and the connections to the sources of the same switching elements, so that the drains and sources of the same switching elements are not connected to each other via conductive surfaces. This allows for efficient switching organization. Additionally, it can help provide a favorable commutation loop.

[0023] The first switching element can face the fourth switching element, and the second switching element can face the third switching element. This allows for efficient organization of the switches. Furthermore, it can help provide a favorable commutation loop.

[0024] The power module may include a first supporting conductive element that connects a top substrate to a bottom substrate. A second switching element may be fixed between the first switching element and the first supporting conductive element. A third switching element may be fixed between a fourth switching element and the first supporting conductive element. This allows for efficient organization of the switches. Furthermore, it can help provide a favorable commutation circuit.

[0025] The first, second, third, and fourth switching elements may each include a power semiconductor switch. A power semiconductor switch is an advantageous embodiment of the switching elements of a power module.

[0026] The power module may also include a first cooling element adjacent to a surface of the top substrate facing away from the bottom substrate; and a second cooling element adjacent to a surface of the bottom substrate facing away from the top substrate. This allows for efficient cooling of the power module from both sides.

[0027] Those skilled in the art will understand that the above features can be combined in any way that they deem useful. Attached Figure Description

[0028] This disclosure will be described in more detail below with reference to the accompanying drawings. Throughout the drawings, similar items may be indicated by the same reference numerals. The drawings are illustrative and may not be drawn to scale.

[0029] Figure 1 A diagram of the 3L-TNPC inverter is shown.

[0030] Figure 2 A sketch of the printed circuit layout of the 3L-TNPC inverter is shown.

[0031] Figure 3 A cross-sectional view of the 3L-TNPC inverter package is shown.

[0032] Figure 4 It shows Figure 3 Exploded view of the 3L-TNPC inverter package.

[0033] Figure 5 This illustrates various aspects of inverter packaging and its assembly process.

[0034] Figure 6 The performance aspects of the 3L-TNPC inverter are illustrated. Detailed Implementation

[0035] Certain exemplary embodiments will be described in more detail with reference to the accompanying drawings. The disclosures in the specification, such as detailed constructions and elements, are provided to aid in a comprehensive understanding of the exemplary embodiments. Therefore, it will be apparent that the exemplary embodiments can be performed without those specific limitations. Furthermore, well-known operations or structures are not described in detail, as this would obscure them with unnecessarily detailed descriptions.

[0036] Although different components are referred to as "top" or "bottom" elements in this disclosure for clarity, it should be understood that these concepts are used to indicate two opposite sides of the power module. Furthermore, it should be understood that these concepts are interchangeable. That is, since the power module can be rotated and assembled in any desired orientation, the "top" element can be located below or beside the "bottom" element depending on the current orientation of the power module.

[0037] 3L-TNPC (three-level T-type neutral clamped) inverters are widely used in electrification propulsion applications due to their efficiency, low total harmonic distortion (THD), and low common-mode noise. However, fully utilizing the advantages of wide bandgap (WBG) devices remains challenging. The fast switching speed necessitates low stray inductance (LL) for the power supply loop. stray This includes a design scheme and a robust smart gate driver design that can simultaneously optimize slew rate, overshoot, and switching losses. Additionally, the small size of the WBG device die allows for the provision of power modules with lower thermal resistance.

[0038] Figure 1 A diagram of a 3L-TNPC inverter is shown, including the positive DC terminal DCP, negative DC terminal DCN, neutral terminal N, AC terminal AC, and switches S1 through S4. The 3L-TNPC inverter has proven to offer high efficiency, low THD, and reduced electromagnetic interference (EMI) in applications ranging from 400VDC to 1.2KVDC. The introduction of additional neutral branches (S2 and S3) complicates the commutation circuit, resulting in more complex top commutation circuit (TCL) and bottom commutation circuit (BCL), such as... Figure 1 As shown. Figure 2 The example shown, a typical TNPC-based package with identical switches and terminals, reveals that switches S1-S4 are asymmetrically arranged, resulting in an unbalanced TCL and BCL. In high-power applications, this asymmetry has been shown to lead to stray inductance (L... stray The 6 nH difference in )

[0039] This disclosure provides a package design for a 1.2kV / 300A 3L-TNPC inverter with a vertical structure. This vertical structure can have one or both of the following advantages. First, it can reduce the unbalanced stray inductance between the TCL and BCL. Second, it enables dual-sided cooling, resulting in lower power module thermal impedance.

[0040] This disclosure provides a package design with balanced stray inductance between two current commutation loops (TCL and BCL). Furthermore, in some embodiments, the stray inductance in the two commutation loops can be reduced to less than 4 nH. In some embodiments, it is possible to reduce the thermal impedance of the power module to 0.2 K / W. In some embodiments, both low stray inductance and low thermal impedance can be achieved simultaneously.

[0041] The power modules disclosed herein are applicable to SiC (silicon carbide) and GaN (gallium nitride) based devices. However, this is not a limitation. Other types of devices can be used as components of the power modules.

[0042] Figure 3 A cross-sectional view of the molded package is shown. Figure 4 An exploded perspective view of the package is shown. Switches S1 and S2 are located on the top side, while switches S3 and S4 are located on the bottom side. A secondary substrate is used for switches S2 and S3. A copper pillar 301 is used to implement the AC connection, while another copper pillar 302 implements the drain connection between switches S2 and S3. These two copper pillars also serve as mechanical supports within the package. Instead of copper, any suitable material can be chosen as the conductive support element. The support element can be configured to hold the top and bottom (secondary) substrates at a fixed distance from each other. The pillars can be made of a material that provides sufficient support and conductivity. Alternatively, the pillars can be made of a non-conductive material, in addition to the conductive path provided by means of, for example, a conductive coating on the pillar or a conductive wire. For example, bonding wires or copper clips can be used for interconnecting different bare dies. Decoupling capacitors (C1 and C2) are placed between terminals DCP, N, and DCN to provide a path for high-frequency current commutation. These decoupling capacitors C1 and C2 can be provided in a package, such as a 1210 package. To increase current capability, two bare SiC dies can be connected in parallel, such as... Figure 5 As shown.

[0043] As in Figure 5 As best seen, two gate interface boards 521 and 522 are inserted on both the top and bottom sides to provide access to the gates of switches S1, S2, S3, and S4 via corresponding gate terminals 523. The gates and sources of the bare SiC die are electrically connected to the circuit using bonding wires 303. Commutation loops 305 and 306 are... Figure 3As shown in the diagram, curved arrow 305 indicates the top commutation loop (TCL), and curved arrow 306 indicates the bottom commutation loop (BCL). It can be seen that two symmetrical commutation loops are implemented. The commutation loops have overlapping positions and opposite directions, so they can partially or completely cancel out unwanted inductive effects from each other.

[0044] like Figure 3 As shown, two cooling elements 321 and 322 can be arranged such that there are cooling elements on both sides of the package 300. Therefore, the first cooling element 321 can be disposed near the surface of the top substrate 311, which faces away from the bottom substrate 312, and the second cooling element 322 can be disposed near the surface of the bottom substrate 312, which faces away from the top substrate 311. This effectively removes heat dissipated by the power unit. The cooling elements can be implemented as containers, for example, fluidly connected to a heat exchanger in a loop, such that the package 300 is cooled by flowing coolant through the containers. Other types of cooling elements are also envisioned (such as passive coolers, such as fins cooled by airflow).

[0045] Figure 5 Various aspects of a possible assembly process are illustrated. In the example assembly process, packages with two identical parallel circuits are generated side by side. However, this is not a limitation. Packages with a single circuit are possible. Similarly, packages with any desired number of parallel circuits can be manufactured by extending the teachings disclosed herein. In parallel circuits, the corresponding terminals of each circuit can be electrically connected to each other to combine the power supply of all circuits into a set of terminals DCP, N, DCN, and AC.

[0046] List 503 illustrates the steps in fabricating the top secondary portion 511. In step 1, the top secondary substrate 313 is fabricated by etching desired electrical paths in one or more conductive layers of the substrate 313. In step 2, a switch S2 is molded on a surface, wherein the drain and source are electrically connected to an electrical surface layer of the top secondary substrate 313, and the drain is electrically isolated from the gate and source. In some embodiments, the drain side is electrically connected to and molded onto the conductive surface layer of the top secondary substrate, and the source is electrically connected to the conductive surface layer of the top secondary substrate 313 via bonding wire 315. However, other connection configurations are also possible.

[0047] List 504 illustrates the steps in fabricating the bottom secondary component 514. In step 1, the bottom secondary substrate 314 is fabricated by etching desired electrical paths in a conductive layer of substrate 314. In step 2, a switch S3 is molded on a surface, wherein the drain and source are electrically connected to an electrical surface layer of the bottom secondary substrate 314, wherein the drain is electrically isolated from the gate and source. In some embodiments, the drain side is electrically connected to and molded onto the conductive surface layer of the bottom secondary substrate 314, and the source is electrically connected to the conductive surface layer of the bottom secondary substrate 314 via bonding wire 316. However, other connection configurations are also possible. Furthermore, in step 2, a pillar 307 is attached to support another substrate 308, referred to herein as N-substrate 308. Also as Figure 3 As shown, the N substrate 308 can be parallel to the other substrates and can be fixed midway between the top substrate 313 and the bottom substrate 312. The pillar 307 and the substrate 308 also electrically connect the gate and source of the switch S3 to the neutral terminal N.

[0048] List 501 illustrates the steps in fabricating the top portion 511. In step 1, the top substrate 311 is fabricated by etching desired electrical paths in one or more conductive layers of the substrate 311. In step 2, the top secondary portion 513 is attached to the substrate 511. This attachment does not necessarily have to be conductive. Furthermore, in the example shown, switch S1 is secured to the top substrate 311 by electrically connecting its drain side to the top substrate 311 to provide an electrical connection to the DCP terminal. In step 3, the source of switch S1 is connected to the substrate 311 via a wire, providing an electrical connection to the AC terminal. Additionally, the gate portion 521 provides separate electrical connections from the gates of switches S1 and S2 to their respective gain terminals 523.

[0049] Column 502 illustrates the steps in fabricating the bottom portion 512. In step 1, the bottom substrate 312 is fabricated by etching desired electrical paths in one or more conductive layers of the substrate 312. In step 2, the bottom secondary portion 514 is attached to the substrate 512. This attachment does not necessarily have to be conductive. Furthermore, in the example shown, switch S4 is fixed to the bottom substrate 312 by electrically connecting its drain side to the bottom substrate 312 to provide electrical connection to the AC terminal. In step 3, the source of switch S4 is connected to the substrate 312 via a wire, providing electrical connection to the DCN terminal. Additionally, another gate portion 522 provides separate electrical connections between the gates of switches S3 and S4 to their respective gain terminals 523. Capacitor C2 is also connected to the bottom substrate 312. Furthermore, copper pillars 301 and 302 are fixed to the bottom substrate 311. In step 4, an N-substrate or busbar is attached, with capacitor C1 on top of it.

[0050] Finally, the top portion 511 and the bottom portion 512 are connected (secured together by electrical connection as needed) to form package 300.

[0051] Figure 6 The performance of eight different packages in the tests conducted is shown. Each bar has two parts, showing stray inductance (L) in naphhens (nH) (left bar section 511) and thermal resistance (R) in Kelvin per watt (K / W) (right bar section 512). Bar 501 shows the performance of the Semikron SEMIX 5P 1.2kV 400A. Bar 502 shows the performance of the Infineon EconoPACK 4 1.2kV 300A. Bar 503 shows the performance of the Fuji Electric V Series 1.2kV 300A. Bar 504 shows the performance of the Semikron SKIM4 1.2kV 400A. Bar 505 shows the performance of the Infineon EconoPACK2 1.2kV 150A. Section 506 illustrates the performance of the Infineon EasyPACK 2B 1.2kV 100A. Section 507 illustrates the performance of the Vincotech MNPC X4 1.2kV 400A. These product names currently on the market are trademarks of their respective owners. Section 508 illustrates the performance of the package 300 disclosed herein. Compared to products currently on the market, package 300 exhibits lower stray inductance and lower thermal resistance. The proposed solution results in relatively low stray inductance, approximately 3.5 nH for both the TCL and BCL circuits.

[0052] On the other hand, a method of using the described power module is provided. The method includes supplying DC power to the positive DC terminal, negative DC terminal, and neutral terminal of the power module; supplying an alternating signal to the gate terminal of the switching element; and optionally using a first cooling element and a second cooling element to cool the power module.

[0053] While this disclosure has been described with reference to exemplary embodiments, those skilled in the art will understand that various changes can be made and elements can be substituted with equivalents without departing from the scope of this disclosure. Furthermore, many modifications can be made to adapt particular situations or materials to the teachings of this disclosure without departing from its essential scope. Therefore, it is intended that this disclosure is not limited to the specific embodiments disclosed, but rather that it encompass all embodiments falling within the scope of the appended claims.

Claims

1. A power supply module, comprising: Positive DC terminal (DCP), negative DC terminal (DCN), neutral terminal (N), and AC terminal (AC), among which, The positive DC terminal (DCP) is connected to the AC terminal (AC) via a first switching element (S1). The neutral terminal (N) is connected to the AC terminal (AC) via a third switching element (S3) and a second switching element (S2), and The negative DC terminal (DCN) is connected to the AC terminal (AC) via a fourth switching element (S4); The power module further includes a top substrate (311) and a bottom substrate (312) facing the top substrate (311), wherein at least one of the switching elements (S1, S2, S3, S4) is fixed to the top substrate (311), and at least one of the switching elements (S1, S2, S3, S4) is fixed to the bottom substrate (312).

2. The power module according to claim 1, wherein, The power module further includes a top secondary substrate (313) fixed to the top substrate (311) and a bottom secondary substrate (314) fixed to the bottom substrate (312), wherein the top secondary substrate (313) and the bottom secondary substrate (314) are located between the top substrate (311) and the bottom substrate (312).

3. The power module according to claim 2, wherein, The second switching element (S2) is fixed to the top secondary substrate (313), wherein the top secondary substrate (313) is located between the top substrate (311) and the second switching element (S2), and The third switching element (S3) is fixed to the bottom secondary substrate (314), wherein the bottom secondary substrate (314) is located between the third switching element (S3) and the bottom substrate (312).

4. The power module according to any one of the preceding claims, wherein, The top substrate (311) and the bottom substrate (312) each include two conductive surfaces (309a, 309b) and an insulating layer (309c) is provided between the two conductive surfaces.

5. The power module according to any one of claims 2 to 4, wherein, The top secondary substrate (311) and the bottom secondary substrate (312) each include two conductive surfaces, with an insulating layer between the two conductive surfaces.

6. The power module according to claim 5, which is dependent on claim 4, wherein, The second switching element (S2) is fixed to the top secondary substrate (313), wherein the top secondary substrate (313) is located between the second switching element (S2) and the top substrate (311), and The third switching element is fixed to the bottom secondary substrate, wherein the bottom secondary substrate is located between the third switching element and the bottom substrate.

7. The power module according to any one of the preceding claims further includes a first supporting conductive element (301) for connecting the top substrate (311) to the bottom substrate (312) or a second supporting conductive element (302) for connecting the top secondary substrate (313) to the bottom secondary substrate (314).

8. The power module according to any one of the preceding claims, wherein, The drain side of the first switching element (S1) is fixed to the conductive surface of the top substrate (311), the drain side of the second switching element (S2) is fixed to the conductive surface of the top secondary substrate (313), the drain side of the third switching element (S3) is fixed to the conductive surface of the bottom secondary substrate (314), and the drain side of the fourth switching element (S4) is fixed to the conductive surface of the bottom substrate (312).

9. The power module according to claim 8, wherein, The source of the first switching element (S1) is conductively connected to the conductive surface of the top substrate (311), the source of the second switching element (S2) is conductively connected to the conductive surface of the top secondary substrate (313), the source of the third switching element (S3) is conductively connected to the conductive surface of the bottom secondary substrate (312), and the source of the fourth switching element (S4) is conductively connected to the conductive surface of the bottom substrate (312). In this configuration, the corresponding conductive surface is interrupted between the corresponding drain side and the source of the same switching element, such that the drain and source of the same switching element are not connected to each other via the conductive surface.

10. The power module according to any one of the preceding claims, wherein, The first switching element (S1) faces the fourth switching element (S4), and the second switching element (S2) faces the third switching element (S3).

11. The power module according to claim 10, Includes a first supporting conductive element (301) that connects the top substrate (311) to the bottom substrate (312). in, The second switching element (S2) is fixed between the first switching element (S1) and the first supporting conductive element (301), and The third switching element (S3) is fixed between the fourth switching element (S4) and the first supporting conductive element (301).

12. The power module according to any one of the preceding claims, wherein, The first switching element (S1), the second switching element (S2), the third switching element (S3), and the fourth switching element (S4) each include a power semiconductor switch.

13. The power module according to any one of the preceding claims, wherein, The power module also includes: A first cooling element (321) is adjacent to the surface of the top substrate (311) facing away from the bottom substrate (312); and The second cooling element (322) is adjacent to the surface of the bottom substrate (312) which is opposite to the top substrate (311).

14. A method of using the power module according to claim 13, comprising: DC power is supplied to the positive DC terminal (DCP), the negative DC terminal (DCN), and the neutral terminal (N) of the power module; as well as An alternating signal is provided to the gate terminal (523) of the switching element.

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