Solid state switching power module with improved current rating

Abstract

A solid state switching power module (10) comprising: at least one bipolar semiconductor switch (T1, T2); at least one unipolar semiconductor switch (J1, J2); wherein the at least one bipolar semiconductor switch (T1, T2) is connected in parallel with the at least one unipolar semiconductor switch (J1, J2); wherein the solid state switching power module (10) comprises at least one thermal capacitor, which is connected to a surface of the at least one bipolar semiconductor switch (T1, T2); wherein the at least one heat capacitor is configured to absorb heat from the at least one bipolar semiconductor switch (T1, T2).

Description

Technical Field

[0001] The present disclosure relates to a solid-state switching power module and a contactor device including the solid-state switching power module.

[0002] A circuit breaker device based on solid-state technology can have faster current interruption or current limitation, higher short-circuit breaking capacity, and a higher number of operations without degrading performance. An example of where a mechanical switch may be replaced by a solid-state switch is a contactor device. Such a contactor retains the main benefits of a contactor module utilizing power semiconductors: higher reliability compared to mechanical switches (more switching cycles should be possible). Currently, typical contactor devices are based on thyristor devices with very high current and voltage blocking capabilities. The drawback of this solution is the bipolar nature of the thyristor device, which results in a threshold voltage of several hundred mV. This minimum voltage drop always exists in the thyristor, significantly increasing the device losses and thus limiting the current rating of the contactor and / or increasing the thermal requirements.

[0003] Semiconductor devices based on the wide-bandgap material SiC have recently become mature due to continuous progress in their research and development (R&D). This progress has helped open the door for semiconductors in power electronics (PE) applications. To avoid the bottleneck of thyristor-based contactor devices, a combination of SiC JFET and Si thyristor has been provided as the main switch in a contactor device. The I / V characteristics of the SiC JFET ensure low losses at low currents (normal operation of contactor operation), and during overloads caused by inrush current (also known as surge current), the thyristor should absorb most of the current.

[0004] During the conduction process, a very high inrush current (several times the nominal value) basically only flows through the thyristor for several seconds. The time is too short to see the effect of the cooler, so the current rating of the contactor device is mainly limited by the ability of the module structure near the thyristor to absorb and dissipate energy without overheating the device.

[0005] Therefore, there is a need for a power module for a contactor device with improved current rating. Summary of the Invention

[0006] The present invention is defined by the subject matter of the independent claims. Additional features of the present invention are set out in the dependent claims.

[0007] According to one aspect of the present invention, a solid-state switching power module includes at least one bipolar semiconductor switch and at least one unipolar semiconductor switch. The at least one bipolar semiconductor switch is connected in parallel with the at least one unipolar semiconductor switch. The solid-state switching power module includes at least one heat capacity, and the at least one heat capacity is connected to the surface of the at least one bipolar semiconductor switch. The at least one heat capacity is configured to absorb heat from the at least one bipolar semiconductor switch.

[0008] In other words, in the case where an overload current flows through the at least one bipolar semiconductor switch, the at least one heat capacity allows the absorption of heat generated by the overload current flowing through the at least one bipolar semiconductor switch. This allows an increase in the current rating of the solid-state switching power module.

[0009] In the case where an overload current passes through the solid-state switching power module, for example, when the solid-state switching power module is turned on, most of this increased current flows through the at least one bipolar semiconductor switch. Due to the parallel connection of the at least one bipolar semiconductor switch and the at least one unipolar semiconductor switch, when the solid-state switching power module is turned on, most of the overload current flows through the at least one bipolar semiconductor switch. Therefore, the current rating of the solid-state switching power module is limited by the ability of the solid-state switching power module to absorb or dissipate the heat generated by the overload current flowing through the at least one bipolar semiconductor switch. Generally, the at least one bipolar semiconductor switch is mounted in a direct-bonded copper DBC, and the direct-bonded copper acts as a thermal insulator rather than a thermal conductor. Thus, the heat sink typically mounted on the other side of the DBC is quite limited in its ability to absorb or dissipate the overload heat from the at least one bipolar semiconductor switch.

[0010] Compared with conventional cooling devices (such as a heat sink module), the heat capacity directly connected to the at least one bipolar semiconductor switch allows the at least one bipolar semiconductor switch to withstand a higher overload current, and thus allows the solid-state switching power module to be sized to have an increased current rating.

[0011] In other words, the heat capacity is directly connected to the at least one bipolar semiconductor switch, and thus allows the rapid absorption of heat caused by the operation of the at least one bipolar semiconductor switch, especially by the operation with an overload current. Therefore, the heat capacity is sized such that the heat capacity is assembled into the package of the solid-state switching power module, connected to the surface of the at least one bipolar semiconductor switch, and has sufficient heat capacity and thermal connectivity to absorb the heat generated by the at least one bipolar semiconductor switch through which the overload current flows.

[0012] As used herein, the term "absorb heat" includes not only the absorption of heat, but also the dissipation of the absorbed heat.

[0013] Preferably, the heat capacity is connected to the surface of each bipolar semiconductor switch of the at least one bipolar semiconductor switch. In other words, each bipolar semiconductor switch of the at least one bipolar semiconductor switch is directly connected to the heat capacity.

[0014] Preferably, the overload current (which is also referred to as inrush current in the case of switching on) is higher than the nominal current flowing through the solid-state switch power module during normal operation, in particular several times higher.

[0015] The heat capacity is a relatively small structure. The at least one heat capacity provides a relatively inexpensive solution for increasing the current rating of the solid-state switch power module.

[0016] For example, a solid-state switch power module for a contactor device has a current rating of 10 amperes, while the proposed solid-state switch power module provides a current rating of approximately 20 amperes.

[0017] Therefore, a power module for a contactor device with an improved current rating is provided.

[0018] In a preferred embodiment, the solid-state switch power module includes a direct-bonded copper DBC, where the at least one bipolar semiconductor switch is disposed on a first side of the DBC. A heat sink module is disposed on a second side of the DBC. The heat sink module is configured to absorb heat from the at least one bipolar semiconductor switch and the at least one unipolar semiconductor switch.

[0019] The DBC preferably includes a base plate, solder, and thermal paste that increase the thermal resistance of the solid-state switch power module, limiting the ability of the heat sink to absorb heat.

[0020] During normal operation of the solid-state switch power module, the heat sink module absorbs and dissipates the heat generated by the operation of the solid-state switch power module, in particular by the operation of the at least one bipolar semiconductor switch and / or the at least one unipolar semiconductor switch. However, as described above, the heat sink module is located on the opposite side of the DBC compared to the semiconductor switch. Therefore, the heat generated by the overload current flowing through the at least one bipolar semiconductor switch cannot be efficiently absorbed and dissipated by the heat sink module.

[0021] In other words, the heat sink module is configured to absorb the normal operating heat of the solid-state switch power module and thus of the at least one bipolar semiconductor switch. The normal operating heat includes the heat generated by the operation of the at least one bipolar semiconductor switch and the at least one unipolar semiconductor switch due to their operation with the nominal current. In contrast, the at least one heat capacity is configured to absorb the overcurrent heat of the at least one bipolar semiconductor switch. The overcurrent heat includes the heat generated by the operation of the at least one bipolar semiconductor switch due to its operation with an overcurrent.

[0022] Alternatively, instead of using a DBC, a printed circuit board (PCB) is used to set the semiconductor switch to conducting.

[0023] In a preferred embodiment, the at least one heat sink is disposed on the top side of the at least one bipolar semiconductor switch, where the top side is the side of the at least one bipolar semiconductor switch facing away from the DBC.

[0024] Since there is typically some space above the at least one bipolar semiconductor switch within the package of the solid-state switch power module, the at least one heat sink is disposed and connected on the top side of the at least one bipolar semiconductor switch. This provides space for the heat sink within the solid-state switch power module and also provides sufficient space for dissipating at least some of the absorbed heat into the environment.

[0025] In a preferred embodiment, the heat sink is disposed on the bottom side of the at least one bipolar semiconductor switch, where the bottom side is the side of the at least one bipolar semiconductor switch facing the DBC.

[0026] In other words, the at least one heat sink is disposed between the at least one bipolar semiconductor switch and the DBC. The at least one bipolar semiconductor switch thus does not require a specific connecting device for the heat sink because the at least one bipolar semiconductor switch is directly connected to the DBC via the at least one heat sink.

[0027] In a preferred embodiment, the at least one heat sink includes a first heat sink and a second heat sink. The first heat sink is disposed on the top side of the at least one bipolar semiconductor switch, where the top side is the side of the at least one bipolar semiconductor switch facing away from the DBC, and the second heat sink is disposed on the bottom side of the at least one bipolar semiconductor switch, where the bottom side is the side of the at least one bipolar semiconductor switch facing the DBC.

[0028] In other words, the first heat sink is disposed on top of the at least one bipolar semiconductor switch, and the second heat sink is disposed between the at least one bipolar semiconductor switch and the DBC. This allows for flexible use of the available space within the package of the solid-state switch power module. Additionally, this increases the heat dissipation from the at least one bipolar semiconductor switch to the at least one heat sink due to the increased connection surface (i.e., the top and bottom sides of the at least one bipolar semiconductor switch).

[0029] This allows for a further increase in the overload current passing through the at least one bipolar semiconductor switch.

[0030] Therefore, a power module for a contactor device with improved current rating is provided.

[0031] In a preferred embodiment, the heat sink includes a preform.

[0032] As used herein, the term "preform" includes welded molded parts. The preform can be made of different materials / compounds and in different forms. Preferably, the welding volume of the preform is adjusted to the welding points, in particular to the connection surfaces of the at least one bipolar semiconductor switch.

[0033] This allows for an easy connection of the heat sink to the at least one bipolar semiconductor switch.

[0034] In a preferred embodiment, the surface of the at least one bipolar semiconductor switch includes connection means for connecting to the at least one heat sink.

[0035] Preferably, the connection means includes any one of pads, clip connections, and wire bonding.

[0036] Preferably, the connection means allows for a high thermal conductivity connection between the at least one heat sink and the at least one bipolar semiconductor switch.

[0037] In a preferred embodiment, the heat sink has a weldable, sinterable surface treatment for connection to the metallization layer of the at least one bipolar semiconductor switch.

[0038] The surface treatment of the heat sink preferably includes silver, copper, nickel, or gold.

[0039] In a preferred embodiment, the at least one heat sink includes a structure at the surface of the heat sink for improving heat dissipation.

[0040] Preferably, the structure includes at least one pin or at least one groove to improve heat dissipation from the heat sink to, for example, the environment. Heat dissipation is also referred to as heat radiation.

[0041] In a preferred embodiment, the at least one bipolar semiconductor switch includes a thyristor, and the at least one unipolar semiconductor switch includes a junction gate field effect transistor JFET.

[0042] In a preferred embodiment, the JFET is a silicon carbide (SiC) JFET or a gallium nitride (GaN) JFET.

[0043] In a preferred embodiment, the heat sink covers at least 90% of the surface of the bipolar semiconductor switch.

[0044] In a preferred embodiment, the thickness of the heat sink is between 0.5 mm and 10 mm.

[0045] Thus, the thick metallization layer of the at least one bipolar semiconductor switch does not provide sufficient heat capacity.

[0046] In a preferred embodiment, the heat sink is at least partially made of copper, aluminum, molybdenum, and / or their combinations.

[0047] Copper, aluminum, molybdenum, and / or their combinations provide relatively high heat capacity and thermal conductivity. Importantly, the heat capacity can provide sufficient heat capacity and thermal conductivity to dissipate heat from the at least one bipolar semiconductor switch caused by operating the at least one bipolar semiconductor switch with an overloaded current.

[0048] According to another aspect of the present invention, a contactor device includes a solid-state switch power module as described herein.

[0049] The subject matter of the present invention will be explained in more detail hereinafter with reference to the preferred exemplary embodiments shown in the drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] Exemplary embodiments of the present invention will be described hereinafter with reference to the drawings:

[0051] Figure 1 An electrical schematic diagram of the semiconductor switch of the solid-state switch power module is shown; and

[0052] Figure 2 The solid-state switch power module according to the present invention is shown. DETAILED DESCRIPTION

[0053] Figure 1 An electrical schematic diagram of the semiconductor switch of the solid-state switch power module 10 is shown.

[0054] The solid-state switch power module 10 includes an input node Ni into which an input current flows into the solid-state switch power module 10. In addition, the solid-state switch power module 10 includes an output node No from which an output current flows out of the solid-state switch power module 10.

[0055] The solid-state switch power module 10 includes a first branch 11, also referred to as a bipolar-based branch. In addition, the solid-state switch power module 10 includes a second branch 12, also referred to as a unipolar-based branch. The first branch 11 and the second branch 12 are connected in parallel, and both connect the input node Ni to the output node No.

[0056] The first branch 11 includes a first thyristor T1 and a second thyristor T2. The first thyristor T1 and the second thyristor T2 are bipolar semiconductor switches. The first thyristor T1 and the second thyristor T2 are connected in parallel with each other. In addition, the first thyristor T1 includes a first anode connected to the input node Ni and a first cathode connected to the output node No. In addition, the second thyristor T2 includes a second anode connected to the output node No and a second cathode connected to the input node Ni.

[0057] The second branch 12 includes a first JFET J1, a second JFET J2, a first MOSFET M1, and a second MOSFET M2 connected in series with each other. The first JFET J1 is connected to the input node Ni and the first MOSFET M1. The first MOSFET M1 is connected to the first JFET J1 and the second MOSFET M2, and the second MOSFET M2 is connected to the first MOSFET M1 and the second JFET J2. The second JFET J2 is connected to the second MOSFET M2 and the output node No.

[0058] Since the first JFET J1 and the second JFET J2 are normally-on devices, the first MOSFET M1 and the second MOSFET M2 must connect the first JFET J1 and the second JFET J2 in series.

[0059] The combination of the thyristor-based first branch 11 and the JFET-based second branch 12 is also referred to as a ThyFET. The ThyFET allows for low losses at low currents in the second branch 12, while the first branch absorbs most of the current, especially that caused by inrush current, during overload.

[0060] Figure 2 A solid-state switching power module 10 according to the present invention is shown. Consistent with Figure 1 the schematic Figure 1 thereof, the solid-state switching power module 10 includes a first thyristor T1, a second thyristor T2, a first JFET J1, a second JFET J2, a first MOSFET M1, and a second MOSFET M2 having the same layout as shown. As Figure 1 sketched in Figure 1 , the first thyristor T1 or the second thyristor T2 absorbs most of the inrush current in the on state. The inrush current causes rapid heat generation in the first thyristor T1 or the second thyristor T2. Thus, the solid-state switching power module 10 has a current rating determined by the ability of the components of the solid-state switching power module 10, especially the first thyristor T1 and the second thyristor T2, and further especially the first thyristor T1 and the second thyristor T2, to handle the inrush current.

[0061] The solid-state switching power module 10 includes a DBC 20. The semiconductor switches are mounted on the top side of the DBC. A heat sink module (not shown) is provided on the bottom side opposite the top side, and the heat sink module is configured to absorb and dissipate the heat generated by the solid-state switching power module 10. However, the DBC acts as a thermal insulator rather than a thermal conductor. Therefore, in the case of a rapid heat surge that occurs, for example, during the flow of inrush current through the first thyristor T1 or the second thyristor T2, the heat sink module responds insufficiently to absorb and dissipate most of the so-called overload heat.

[0062] ​Thus, the solid-state switch power module 10 has a current rating that is specifically sized depending on the ability of the first thyristor T1 and the second thyristor T2 not to overheat due to inrush current. Thus, the first thyristor T1 and the second thyristor T2 must not exceed a predetermined temperature, in particular 150 degrees Celsius. In other words, the current rating of the solid-state switch power module 10 is limited by the ability of the first thyristor T1 and the second thyristor T2 to remain below 150 degrees Celsius during turn-on, where the inrush current flows through the first thyristor T1 or the second thyristor T2.

[0063] Thus, the first thyristor T1 is directly connected to a first heat capacity in the form of a preform P1, and the second thyristor T2 is directly connected to a second heat capacity in the form of a second preform P2. For example, these connections include welding, sintering, gluing, transient liquid phase, TLP, bonding, or soldering.

[0064] The first preform P1 and the second preform P2 comprise materials having a high heat capacity and high heat connectivity. Thus, during turn-on, the overload heat caused by the inrush current flowing through the first thyristor and / or the second thyristor is absorbed and dissipated by the first preform P1 and the second preform P2.

[0065] In other words, the first preform P1 and the second preform P2 are correspondingly directly connected to the first thyristor T1 and the second thyristor T2, in particular directly mounted on the surface or side of the respective first thyristor T1 and second thyristor T2, thereby allowing a significant portion of the generated overload heat to be handled. Compared to the solid-state switch power module 10 without the preforms P1, P2, the thyristors T1, T2 have a temperature that is 8 to 20 degrees Celsius lower. Thus, the preforms P1, P2 allow an increase in the current rating of the solid-state switch power module 10. Preferably, the preforms P1, P2 (in other words, the heat capacities) allow the current rating to be doubled, for example from 10 amperes to 20 amperes.

[0066] Thus, a power module 10 for a contactor device with an improved current rating is provided.

[0067] List of Reference Signs

[0068] 10 Solid-state switch power module

[0069] 20 Direct-bonded copper

[0070] T1 First thyristor

[0071] T2 Second thyristor

[0072] J1 First JFET

[0073] J2 Second JFET

[0074] M1 first MOSFET

[0075] M2 second MOSFET

Claims

1. A solid-state switching power module (10), comprising: at least one bipolar semiconductor switch (T1, T2); at least one unipolar semiconductor switch (J1, J2); wherein the at least one bipolar semiconductor switch (T1, T2) is connected in parallel with the at least one unipolar semiconductor switch (J1, J2); wherein the solid-state switching power module (10) comprises at least one heat capacitor connected to a surface of the at least one bipolar semiconductor switch (T1, T2); The at least one thermal capacitor is configured to absorb heat from the at least one bipolar semiconductor switch (T1, T2).

2. A solid-state switching power module according to any one of the preceding claims, comprising a direct bonded copper DBC (20), wherein the at least one bipolar semiconductor switch (T1, T2) is disposed on a first side of the DBC (20); wherein a heat sink module is disposed on a second side of the DBC (20); The heat sink module is configured to absorb heat from the at least one bipolar semiconductor switch (T1, T2) and the at least one unipolar semiconductor switch (J1, J2).

3. The solid-state switching power module according to claim 2, The at least one thermal capacitor is arranged on a top side of the at least one bipolar semiconductor switch (T1, T2), wherein the top side is a side of the at least one bipolar semiconductor switch (T1, T2) facing away from the DBC (20).

4. The solid-state switching power module according to claim 2, The at least one thermal capacitor is arranged on a bottom side of the at least one bipolar semiconductor switch (T1, T2), wherein the bottom side is a side of the at least one bipolar semiconductor switch (T1, T2) facing the DBC (20).

5. The solid-state switching power module according to claim 2, The at least one heat capacitor comprises a first heat capacitor and a second heat capacitor, wherein the first heat capacitor is arranged on the top side of the at least one bipolar semiconductor switch (T1, T2), wherein the top side is the side of the at least one bipolar semiconductor switch (T1, T2) facing away from the DBC (20), and the second heat capacitor is arranged on the bottom side of the at least one bipolar semiconductor switch (T1, T2), wherein the bottom side is the side of the at least one bipolar semiconductor switch (T1, T2) facing the DBC (20).

6. A solid-state switching power module according to any one of the preceding claims, Wherein the at least one thermal capacitor comprises a preform.

7. A solid-state switching power module according to any one of the preceding claims, A surface of the at least one bipolar semiconductor switch (T1, T2) comprises a connection device connected to the heat capacitor.

8. A solid-state switching power module according to any one of the preceding claims, The heat capacitor has a solderable, sinterable surface treatment for connection to a metallization of the at least one bipolar semiconductor switch (T1, T2).

9. A solid-state switching power module according to any one of the preceding claims, Wherein the at least one heat capacitor comprises structure at a surface of the heat capacitor for improving heat dissipation.

10. A solid-state switching power module according to any one of the preceding claims, wherein the at least one bipolar semiconductor switch (T1, T2) comprises a thyristor; and The at least one unipolar semiconductor switch (J1, J2) comprises a junction gate field effect transistor (JFET).

11. The solid-state switching power module according to claim 10, The JFET is a silicon carbide SiC JFET or a gallium nitride GaN JFET.

12. A solid-state switching power module according to any one of the preceding claims, Wherein the at least one thermal capacitance covers at least 90% of the surface of the bipolar semiconductor switch (T1, T2).

13. A solid-state switching power module according to any one of the preceding claims, The thickness of the at least one heat capacitor is between 0.5 mm and 10 mm.

14. A solid-state switching power module according to any one of the preceding claims, Wherein the at least one heat capacitor is at least partially made of copper, aluminum, molybdenum and / or combinations thereof.

15. A contactor device comprising a solid-state switching power module (10) according to any one of claims 1-14.

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