Switching module

Abstract

To reduce exceeding of an allowable limit of timing deviations in a plurality of switching elements having Kelvin-connected wiring and connected in parallel to one another.SOLUTION: A switching module 100 according to the present disclosure includes: a plurality of switching elements SW1 to SWn each having a first electrode Ef, a second electrode Es, and a control electrode Ec; a first electrode wiring Wf; a second electrode wiring Ws; a control electrode wiring Wc; and a Kelvin wiring Wk including a common Kelvin wiring Wkc and individual Kelvin wirings Wki1 to Wkin that electrically connect the common Kelvin wiring to the second electrodes of the plurality of switching elements. A Kelvin wiring predetermined portion Pk is an individual Kelvin wiring corresponding to at least one of the plurality of switching elements and has a resistance value of 1 mΩ or more, or a Kelvin wiring predetermined portion Pk is at least a part of the common Kelvin wiring and has a resistance value of 3 mΩ or more.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] The present invention relates to a switching module. [Background technology]

[0002] It is conventionally known to provide a switching element with a Kelvin-connected wiring and apply a gate voltage between the Kelvin-connected wiring and the gate of the switching element.

[0003] Furthermore, Patent Document 1 describes that in a power module including switching elements, the current flowing through Kelvin-connected wiring and the current flowing between main terminals of the switching elements are separated. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2019-220563 A (see especially paragraphs

[0116] -

[0117] and FIG. 22) Summary of the Invention [Problem to be solved by the invention]

[0005] In recent years, wide band gap semiconductors such as SiC and GaN have been adopted as switching elements, and the operation speed of the switching elements has increased accordingly. In addition, the current capacity of the switching elements has increased. On the other hand, in the manufacture of wide band gap semiconductors, crystal defects in the substrate reduce the yield, limiting the expansion of the size of the chip incorporating the switching element. Therefore, when a switching element using a wide band gap semiconductor is applied to a high current capacity application, multiple switching elements connected in parallel are used instead of a single switching element in a low current capacity application.

[0006] However, when multiple switching elements connected in parallel to one another each have Kelvin-connected wiring, there are cases where the timing lag in turning on or off (hereinafter referred to as switching) the switching elements exceeds an allowable limit.

[0007] The present invention has been made to solve such problems, and has an object to provide a switching module which has Kelvin-connected wiring and a plurality of switching elements connected in parallel with each other, and which can reduce deviations in the switching timing of the switching elements from exceeding the allowable limit. [Means for solving the problem]

[0008] <The knowledge that led to this invention> The inventors have conducted intensive research to solve the above-mentioned problems, and in the process have discovered a phenomenon in which, when a switching module in which multiple switching elements connected in parallel with each other and each have Kelvin-connected wiring is operated at high speed, depending on the layout conditions of the switching elements and wiring, a part of the main current of the multiple switching elements is diverted to the Kelvin-connected wiring, and switching noise caused by the parasitic impedance of the wiring of the switching module is superimposed on the diverted current. This phenomenon was unexpected by the inventors. The inventors have investigated the cause by simulations, etc., which will be described later, and have concluded that the cause of this phenomenon occurs as follows.

[0009] When multiple switching elements connected in parallel to each other are used instead of one switching element, the Kelvin-connected wiring (hereinafter referred to as Kelvin sense wiring) of the multiple switching elements may be connected by a common Kelvin wiring. On the other hand, a parasitic resistance exists in the wiring that supplies the main current to the multiple switching elements connected in parallel to each other, and generally, a potential difference occurs between the sources of the multiple switching elements due to the parasitic resistance. In this state, when the common Kelvin wiring connects the sources of the multiple switching elements, a short-circuit current flows so that the sources of the multiple switching elements have a potential difference according to the resistance value of the Kelvin sense wiring and the common Kelvin wiring. Specifically, this short-circuit current flows out from the Kelvin sense wiring of the switching element with a high source potential, flows back through the Kelvin sense wiring of the switching element with a low source potential, and joins the main current of the switching element. As a result, in the switching element with a high source potential, the main current decreases by the amount of the outflowing short-circuit current, causing the source potential to drop, while in the switching element with a low source potential, the main current increases by the amount of the merged short-circuit current, causing the source potential to rise, and the magnitude of the short-circuit current is determined so that the decrease in the potential difference between the sources of both switching elements and the decrease in the short-circuit current are balanced. This short-circuit current is called "shunt current."

[0010] The inventors have then reached the conclusion that the above-mentioned problem occurs when this "shunt" of the main current fluctuates due to switching noise and exceeds a limit.

[0011] As a result of various investigations, it was found that by increasing the resistance of the Kelvin sense wire or the common Kelvin wire, it is possible to reduce the shunting of part of the main current of the multiple switching elements to the Kelvin sense wire and the switching noise superimposed on the shunting. In this case, it is presumed that the high resistance of the Kelvin sense wire or the common Kelvin wire suppresses the shunting itself and also functions as a damper to suppress fluctuations in the shunting.

[0012] The present invention has been made based on such findings, and in order to achieve the above-mentioned object, a switching module according to an aspect of the present disclosure is a switching module in which a plurality of switching elements are connected in parallel, the switching module comprising: a plurality of switching elements each having a first electrode, a second electrode, and a control electrode that controls a main current flowing between the first electrode and the second electrode by a potential difference relative to the second electrode; first electrode wiring electrically connected to the first electrode of each of the plurality of switching elements; second electrode wiring electrically connected to the second electrode of each of the plurality of switching elements; control electrode wiring electrically connected to the control electrode of each of the plurality of switching elements; and Kelvin wiring including a common Kelvin wiring and individual Kelvin wiring electrically connecting the common Kelvin wiring to the second electrode of each of the plurality of switching elements, wherein a Kelvin wiring predetermined portion that is at least a part of the Kelvin wiring is the individual Kelvin wiring corresponding to at least one of the plurality of switching elements and has a resistance value of 1 mΩ or more, or the Kelvin wiring predetermined portion is at least a part of the common Kelvin wiring and has a resistance value of 3 mΩ or more. Effect of the Invention

[0013] The present invention has the advantage of being able to provide a switching module having a plurality of switching elements with Kelvin-connected wiring and connected in parallel with each other, thereby making it possible to reduce deviations in the switching timing of the switching elements from exceeding an allowable limit. [Brief description of the drawings]

[0014] [Figure 1A] FIG. 1A is a circuit diagram illustrating an overview of a first configuration example of a switching module according to an embodiment of the present disclosure. [Figure 1B] FIG. 1B is a circuit diagram illustrating an overview of a second configuration example of a switching module according to an embodiment of the present disclosure. [Figure 2A] FIG. 2A is a perspective view showing the appearance of a discrete component incorporating a single switching element. [Figure 2B] FIG. 2B is a circuit diagram showing an equivalent circuit of the discrete components of FIG. 2A. [Diagram 3] FIG. 3 is a circuit diagram showing an equivalent circuit of one switching element of a module incorporating a plurality of switching elements connected in parallel with one another and internal wiring related thereto. [Figure 4] FIG. 4 is a circuit diagram showing an example of the configuration of a switching module in which the first configuration example of the switching module of FIG. 1A is realized using discrete components incorporating the single switching element of FIGS. 2A and 2B. [Diagram 5] FIG. 5 is a circuit diagram showing an example of the configuration of a switching module in which the first configuration example of the switching module of FIG. 1A is realized using a module incorporating a plurality of switching elements connected in parallel to each other of FIG. [Figure 6] FIG. 6 is a circuit diagram showing an equivalent circuit of the switching module in the first simulation. [Figure 7] FIG. 7 is a graph showing current values ​​of the individual Kelvin wiring in a simulation using the equivalent circuit of FIG. [Figure 8] FIG. 8 is a circuit diagram showing an equivalent circuit of the switching module in the second simulation. [Figure 9] FIG. 9 is a graph showing current values ​​in individual Kelvin wiring in a simulation using the equivalent circuit of FIG. [Figure 10] FIG. 10 is a diagram illustrating the external appearance of a full-bridge type current resonant circuit in which the switching module of FIG. 1A is used as a high-side switching module. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A switching module according to an aspect of the present disclosure is a switching module in which a plurality of switching elements are connected in parallel, the switching elements having a first electrode, a second electrode, and a control electrode for controlling a main current flowing between the first electrode and the second electrode by a potential difference with respect to the second electrode, a first electrode wiring electrically connected to the first electrode of each of the plurality of switching elements, a second electrode wiring electrically connected to the second electrode of each of the plurality of switching elements, a control electrode wiring electrically connected to the control electrode of each of the plurality of switching elements, and Kelvin wiring including a common Kelvin wiring and individual Kelvin wiring electrically connecting the common Kelvin wiring and the second electrode of each of the plurality of switching elements, wherein a Kelvin wiring predetermined portion which is at least a part of the Kelvin wiring is the individual Kelvin wiring corresponding to at least one of the plurality of switching elements and has a resistance value of 1 mΩ or more, or the Kelvin wiring predetermined portion is at least a part of the common Kelvin wiring and has a resistance value of 3 mΩ or more. Here, the "common Kelvin wiring" is a concept including a Kelvin wiring terminal.

[0016] According to this configuration, the Kelvin wiring predetermined portion is an individual Kelvin wiring corresponding to at least one of the multiple switching elements and has a resistance value of 1 mΩ or more, or the Kelvin wiring predetermined portion is at least a part of the common Kelvin wiring and has a resistance value of 3 mΩ or more, so that, compared to a case where the Kelvin wiring has only parasitic resistance, during the on-period of the switching element, a part of the main current is reduced from being shunted to the individual Kelvin wiring and the common Kelvin wiring, and switching noise (hereinafter sometimes simply referred to as "superimposed switching noise") caused by the parasitic impedance of various wirings superimposed on the shunt (hereinafter sometimes simply referred to as "shunt") is reduced. As a result, it is possible to reduce the deviation in the switching timing of the switching element from exceeding the allowable limit.

[0017] The plurality of switching elements may be n (n is an integer of 2 or more) switching elements, and the predetermined portion of the Kelvin wiring may be the individual Kelvin wiring corresponding to n or n-1 of the switching elements.

[0018] According to this configuration, when the Kelvin wiring designated portion is an individual Kelvin wiring corresponding to n switching elements, the individual Kelvin wiring corresponding to all switching elements has a resistance value of 1 mΩ or more, so "shunting" and "superimposition of switching noise" are clearly reduced. Also, when the Kelvin wiring designated portion is an individual Kelvin wiring corresponding to n-1 switching elements, whether or not the individual Kelvin wiring corresponding to the remaining switching element is a Kelvin wiring designated portion does not have a significant effect on the current value of "shunting", so "shunting" and "superimposition of switching noise" are clearly reduced in almost the same way as when the Kelvin wiring designated portion is an individual Kelvin wiring corresponding to n switching elements.

[0019] The predetermined portion of the Kelvin wiring may have a resistance value of 4 mΩ or more. With this configuration, "shunt current" and "superimposition of switching noise" are effectively reduced.

[0020] The predetermined portion of the Kelvin wiring may have a resistance value of 10 mΩ or more. This configuration effectively reduces "shunt current" and "superimposition of switching noise".

[0021] The predetermined portion of the Kelvin wiring may have a resistance value of 100 mΩ or more. With this configuration, "shunt current" and "superimposition of switching noise" are significantly reduced.

[0022] The common Kelvin wiring may extend to have both ends, the individual Kelvin wiring corresponding to each of the multiple switching elements may be electrically connected to the common Kelvin wiring with a space between them, and the Kelvin wiring specific portion may be a portion of the common Kelvin wiring between a pair of locations where the individual Kelvin wiring of each of a pair of adjacent switching elements is connected, corresponding to all of the switching elements. Hereinafter, the "portion of the common Kelvin wiring between a pair of locations where the individual Kelvin wiring of each of a pair of adjacent switching elements is connected" will be referred to as the "common Kelvin wiring specific portion."

[0023] According to this configuration, the predetermined portion of the Kelvin wiring is a specific portion of the common Kelvin wiring corresponding to all switching elements and has a resistance value of 3 mΩ or more, so that "shunting" and "superimposition of switching noise" are clearly reduced.

[0024] The predetermined portion of the Kelvin wiring may have a resistance value of 12 mΩ or more.

[0025] This configuration effectively reduces "shunt current" and "superimposition of switching noise."

[0026] The predetermined portion of the Kelvin wiring may have a resistance value of 30 mΩ or more.

[0027] This configuration significantly reduces "shunt current" and "superimposition of switching noise."

[0028] 7. The switching module according to claim 6, wherein the predetermined portion of the Kelvin wiring has a resistance value of 300 mΩ or more. According to this configuration, "shunt current" and "superimposition of switching noise" are reduced significantly.

[0029] The sum of the resistance value of the predetermined portion of the Kelvin wiring and the resistance value of a control electrode resistor arranged on the control electrode wiring of a switching element corresponding to the predetermined portion of the Kelvin wiring may be a recommended gate resistance value of the switching element.

[0030] According to this configuration, the substantial resistance value of the control electrode resistance of the switching element corresponding to the predetermined portion of the Kelvin wiring becomes equal to the recommended gate resistance value of the switching element, so that the switching element can be operated suitably.

[0031] The predetermined portion of the Kelvin wiring may have a resistance value of 1 kΩ or less.

[0032] According to this configuration, by selecting an appropriate resistance value of 1 kΩ or less as the resistance value of the specified portion of the Kelvin wiring, the resistance value of the actual control electrode resistance of the switching element corresponding to the specified portion of the Kelvin wiring can be made equal to the recommended gate resistance value of the switching element, thereby allowing the switching element to operate optimally.

[0033] The control electrode wiring may include a common control electrode wiring having one end connected to a control wiring terminal and the other end being a termination, and individual control electrode wiring electrically connecting the common control electrode wiring to the control electrodes of each of the plurality of switching elements.

[0034] According to this configuration, the multiple switching elements can be operated as one switching element by a common control electrode drive signal.

[0035] The control electrode wiring may include a plurality of single control electrode wirings, one end of each of which is connected to a respective one of a plurality of control wiring terminals and the other end of each of which is electrically connected to a respective one of the control electrodes of the plurality of switching elements.

[0036] According to this configuration, by inputting a plurality of control electrode drive signals different from one another to the plurality of control wiring terminals, it is possible to operate the plurality of switching elements in different ways from one another.

[0037] The switching element may be an IGBT, a field effect transistor or a bipolar transistor.

[0038] According to this configuration, the switching module can be easily configured.

[0039] Hereinafter, specific embodiments of the present disclosure will be described with reference to the drawings. In the following, the same or corresponding elements are denoted by the same reference numerals throughout all the drawings, and their repeated description will be omitted. In addition, since the following drawings are for explaining the present disclosure, elements unrelated to the present disclosure may be omitted, dimensions may be inaccurate due to exaggeration, or may be simplified, and the shapes of corresponding elements in multiple drawings may not match. In addition, the present disclosure is not limited to the following embodiments.

[0040] (Embodiment) First, an overview of a switching module 100 according to an embodiment of the present disclosure will be described.

[0041] [overview] The switching module 100 includes a first configuration example and a second configuration example.

[0042] {Configuration of the first configuration example} 1A is a circuit diagram showing an overview of a first configuration example of a switching module 100 according to an embodiment of the present disclosure. The first configuration example is configured to operate a plurality of switching elements SW1 to SWn as if they were a single switching element. The first configuration example is designed so that the plurality of switching elements SW1 to SWn are turned on at the same predetermined on-timing and turned off at the same predetermined off-timing, and allowable limits are set for each of the deviations from the on-timing and the off-timing. The first configuration example is applied to, for example, a switching module with a high current capacity.

[0043] 1A, the switching module 100 of the first configuration example includes a plurality of switching elements SW1 to SWn, a first electrode wiring Wf, a control electrode wiring Wc, a second electrode wiring Ws, and a Kelvin wiring Wk. The plurality of switching elements SW1 to SWn are connected in parallel between the first electrode wiring Wf and the second electrode wiring Ws. This configuration will be described in detail below.

[0044] <Switching elements SW1 to SWn> Each of the switching elements SW1 to SWn has a first electrode Ef, a second electrode Es, and a control electrode Ec that controls a main current flowing between the first electrode Ef and the second electrode Es by a potential difference with respect to the second electrode Es. That is, each of the switching elements SW1 to SWn is a transistor. As each of the switching elements SW1 to SWn, for example, a FET (field effect transistor), an IGBT (insulated gate bipolar transistor), a bipolar transistor, or other transistors can be used. Examples of FETs include MOSFETs, MESFETs, and JFETs. In a FET, the first electrode Ef, the second electrode Es, and the control electrode Ec are the drain, source, and gate, respectively. In an IGBT, the first electrode Ef, the second electrode Es, and the control electrode Ec are the collector, emitter, and gate, respectively. In a bipolar transistor, the first electrode Ef, the second electrode Es, and the control electrode Ec are the collector, emitter, and base, respectively.

[0045] <First electrode wiring Wf> The first electrode wiring Wf is electrically connected to the first electrodes Ef of the switching elements SW1 to SWn. The manner of connection between the first electrode wiring Wf and the first electrodes Ef of the switching elements SW1 to SWn is not particularly limited. For example, the first electrode wiring Wf includes a common first electrode wiring Wfc and individual first electrode wirings Wfi1 to Wfin. One end of the first electrode wiring Wf is formed at the first wiring terminal Tf, and the other end is a termination. The first wiring terminal Tf is connected to a high potential terminal of a power source. The common first electrode wiring Wfc is connected to the first electrodes Ef of the switching elements SW1 to SWn by the individual first electrode wirings Wfi1 to Wfin. The material of the first electrode wiring Wf may be any conductive material. For example, copper is used as the material of the first electrode wiring Wf.

[0046] <Second electrode wiring Ws> The second electrode wiring Ws is electrically connected to the second electrodes Es of the switching elements SW1 to SWn. Specifically, the second electrode wiring Ws includes a common second electrode wiring Wsc and individual second electrode wirings Wsi1 to Wsin. One end of the common second electrode wiring Wsc is formed at the second wiring terminal Ts, and the other end is a terminal. The second wiring terminal Ts is connected to the negative terminal of the power supply. The common second electrode wiring Wsc is connected to the second electrodes Es of the switching elements SW1 to SWn by the individual second electrode wirings Wsi1 to Wsin. The manner of connection of the individual second electrode wirings Wsi1 to Wsin corresponding to the switching elements SW1 to SWn to the common second electrode wiring Wsc is not particularly limited. For example, the individual second electrode wirings Wsi1 to Wsin corresponding to the switching elements SW1 to SWn are connected to the common second electrode wiring Wsc with a gap between them. The material of the second electrode wiring Ws may be any conductive material. The second electrode wiring Ws is made of, for example, copper.

[0047] <Control electrode wiring Wc> The control electrode wiring Wc is electrically connected to the control electrodes Ec of each of the switching elements SW1 to SWn. In this first configuration example, the control electrode wiring Wc includes a common control electrode wiring Wcc and individual control electrode wirings Wci1 to Wcin. One end of the common control electrode wiring Wcc is formed at the control wiring terminal Tc and the other end is a termination. The control wiring terminal Tc is connected to a high potential terminal of the control electrode drive circuit. The common control electrode wiring Wcc is connected to the control electrodes Ec of the switching elements SW1 to SWn by the individual control electrode wirings Wci1 to Wcin. A gate resistor Rg is disposed on the common control electrode wiring Wcc between the individual control electrode wiring Wci1 connected to the common control electrode wiring Wcc closest to the control wiring terminal Tc and the control wiring terminal Tc. The material of the second electrode wiring Ws may be any conductive material.

[0048] <Kelvin wiring Wk> The Kelvin wiring Wk is electrically connected to the second electrodes Es of the switching elements SW1 to SWn so as to include the Kelvin sense wiring of each of the switching elements SW1 to SWn. Specifically, the Kelvin wiring Wk includes a common Kelvin wiring Wkc and individual Kelvin wirings Wki1 to Wkin. One end of the common Kelvin wiring Wkc is formed at the Kelvin wiring terminal Tk and the other end is a termination. The Kelvin wiring terminal Tk is connected to the low potential side terminal of the control electrode drive circuit. The common Kelvin wiring Wkc is connected to the second electrodes Es of the switching elements SW1 to SWn by the individual Kelvin wirings Wki1 to Wkin. The individual Kelvin wirings Wki1 to Wkin include the Kelvin sense wiring of each of the corresponding switching elements SW1 to SWn. The portions of the individual Kelvin wirings Wki1 to Wkin other than the Kelvin sense wiring connect the terminal Ks of the Kelvin sense wiring and the common Kelvin wiring Wkc.

[0049] The manner in which the individual Kelvin wires Wki1-Wkin corresponding to the switching elements SW1-SWn are connected to the common Kelvin wire Wkc is not particularly limited. For example, the individual Kelvin wires Wki1-Wkin corresponding to the switching elements SW1-SWn are connected to the common Kelvin wire Wkc at intervals. Also, for example, the entire common Kelvin wire Wkc may be formed on the Kelvin wire terminal Tk, and the individual Kelvin wires Wki1-Wkin may be connected to the Kelvin wire terminal Tk.

[0050] The material of the Kelvin wiring Wk other than the Kelvin wiring designated portion Pk described later may be any conductive material, and copper, for example, is used as the material. The Kelvin wiring designated portion Pk will be described in detail below.

[0051] <Technical features> The Kelvin wiring predetermined portion Pk, which is at least a part of the Kelvin wiring Wk composed of the common Kelvin wiring Wkc and all the individual Kelvin wirings Wki1 to Wkin, is the individual Kelvin wiring Wki1 to Wkin corresponding to at least one of the multiple switching elements SW1 to SWn and has a resistance value of 1 mΩ or more, or the Kelvin wiring predetermined portion Pk is at least a part of the common Kelvin wiring Wkc and has a resistance value of 3 mΩ or more. The technical significance of this technical feature is as follows.

[0052] ≪Technical significance≫ The technical significance of the above technical features will be explained by dividing them into "a lower limit of the resistance value of the Kelvin wiring predetermined portion Pk", "a position of the Kelvin wiring predetermined portion Pk", and "an upper limit of the resistance value of the Kelvin wiring predetermined portion Pk".

[0053] {Lower limit of resistance value of specified part Pk of Kelvin wiring} First, the lower limit of the resistance value of the Kelvin wiring predetermined portion Pk will be described.

[0054] The problem to be solved by the present invention is that when multiple switching elements connected in parallel have Kelvin-connected wiring, the timing difference between the switching elements may exceed the allowable limit. This occurs because a part of the main current of the multiple switching elements is diverted to the Kelvin sense wiring, and the diverted current fluctuates due to switching noise caused by the parasitic impedance of various wirings.

[0055] Therefore, as a countermeasure, if the resistance value of the Kelvin wiring specified part Pk is made higher than the resistance value of the parasitic resistance of the Kelvin wiring specified part Pk, the shunting of the main current to the Kelvin wiring Wk is reduced, and the high resistance of the Kelvin wiring specified part Pk functions as a damper to reduce switching noise. Therefore, in this countermeasure, the larger the resistance value of the Kelvin wiring specified part Pk, the more preferable it is, but it is clear that it is impossible to completely eliminate the shunting of the main current to the Kelvin wiring Wk and the switching noise superimposed on the shunting. On the other hand, a parasitic resistance also exists in the Kelvin sense wiring, and it is clear that this parasitic resistance also suppresses the shunting of the main current to the Kelvin sense wiring ("shunting") and the switching noise superimposed on the shunting ("superimposed switching noise"). However, with the increase in the speed of the operation of the switching element and the increase in the current capacity of the switching element, the parasitic resistance is no longer able to sufficiently suppress the "shunting" and the "superimposed switching noise", and the above problem has arisen. Therefore, it is clear that if the resistance value of at least a part of the Kelvin wiring Wk is made higher than the parasitic resistance of the Kelvin wiring, the "shunting" and "superimposed switching noise" can be reduced. Therefore, in the present invention, it is sufficient that the resistance value of the Kelvin wiring specified part Pk is larger than the resistance value of the parasitic resistance of the Kelvin wiring specified part Pk.

[0056] However, since the parasitic resistance of a general Kelvin sense wiring cannot be clearly specified, the inventors performed two simulations described below in order to clearly distinguish the present invention from the prior art. In the first simulation, a Kelvin wiring predetermined portion Pk was arranged in the individual Kelvin wirings Wki1 to Wkin. In the second simulation, a Kelvin wiring predetermined portion Pk was arranged in a common Kelvin wiring specific portion of the common Kelvin wiring Wkc (a portion in the common Kelvin wiring Wkc between a pair of portions to which the individual Kelvin wirings Wki1 to Wkin of each pair of adjacent switching elements SW1 to SWn are connected).

[0057] The results of the first simulation confirmed the following:

[0058] As the resistance value of the individual Kelvin wirings Wki1 to Wkin including the Kelvin sense wiring increases, the fluctuation of the current of the individual Kelvin wirings Wki1 to Wkin monotonically decreases. The reduction in the fluctuation of the current of the individual Kelvin wirings Wki1 to Wkin means that the "shunting" and "superimposed switching noise" are reduced.

[0059] When the resistance value of the individual Kelvin wirings Wki1 to Wkin is the resistance value (assumed to be 100 μΩ) of the parasitic resistance (hereinafter, sometimes simply referred to as "parasitic resistance") of the individual Kelvin wirings Wki1 to Wkin, the "shunting" and "superimposition of switching noise" are to a certain extent. On the other hand, when the resistance value of the individual Kelvin wirings Wki1 to Wkin is 10 times (1 mΩ) the resistance value of the parasitic resistance, the "shunting" and "superimposition of switching noise" are clearly reduced compared to when the resistance value of the individual Kelvin wirings Wki1 to Wkin is the resistance value of the parasitic resistance (100 μΩ). However, since this simulation is premised on the fact that the Kelvin wiring predetermined portion Pk is provided on the individual Kelvin wirings Wki1 to Wkin of all switching elements SW1 to SWn, for example, when the Kelvin wiring predetermined portion Pk is provided on only the individual Kelvin wiring of one switching element among the multiple switching elements SW1 to SWn, the effect is reduced. However, this certainly increases the resistance value of the entire Kelvin wiring Wk, and therefore certainly reduces "shunt current" and "superimposition of switching noise."

[0060] When the resistance value of the individual Kelvin wirings Wki1 to Wkin is 40 times (4 mΩ) the resistance value of the parasitic resistance, "shunting" and "superimposition of switching noise" are effectively reduced. When the resistance value of the individual Kelvin wirings Wki1 to Wkin is 100 times (10 mΩ) the resistance value of the parasitic resistance, "shunting" and "superimposition of switching noise" are excellently reduced. When the resistance value of the individual Kelvin wirings Wki1 to Wkin is 1000 times (100 mΩ) the resistance value of the parasitic resistance, "shunting" and "superimposition of switching noise" are significantly reduced.

[0061] The results of the second simulation confirmed the following:

[0062] When the resistance value of the common Kelvin wiring specific part is the resistance value of the parasitic resistance (assumed to be 300 μΩ), the "shunting" and "superimposition of switching noise" are of a certain magnitude. On the other hand, when the resistance value of the common Kelvin wiring specific part is 10 times (3 mΩ) the resistance value of the parasitic resistance, the "shunting" and "superimposition of switching noise" are clearly smaller than those when the resistance value of the common Kelvin wiring specific part is the resistance value of the parasitic resistance (300 μΩ). However, since this simulation is premised on the premise that the Kelvin wiring specific part Pk is provided in the common Kelvin wiring specific part corresponding to all switching elements SW1 to SWn, for example, when the Kelvin wiring specific part Pk is provided only in the common Kelvin wiring specific part of one pair of switching elements SW1 to SWn among the multiple switching elements SW1 to SWn, the effect is reduced. However, it is certain that the resistance value of the entire Kelvin wiring Wk is increased, and therefore it is certain that the "shunting" and "superimposition of switching noise" are reduced.

[0063] When the resistance value of the specific portion of the common Kelvin wiring is 40 times (12 mΩ) the resistance value of the parasitic resistance, it is estimated that "shunting" and "switching noise superposition" are significantly reduced. When the resistance value of the specific portion of the common Kelvin wiring is 100 times (30 mΩ) the resistance value of the parasitic resistance, it is estimated that "shunting" and "switching noise superposition" are significantly reduced. When the resistance value of the specific portion of the common Kelvin wiring is 1000 times (300 mΩ) the resistance value of the parasitic resistance, "shunting" and "switching noise superposition" are significantly reduced.

[0064] On the other hand, as far as the inventors know, the parasitic resistances of the Kelvin sense wiring and the specific portion of the common Kelvin wiring are about 100 μΩ and 300 μΩ, respectively. It should be particularly noted here that since the voltage of the control electrode drive signal is applied between the Kelvin-connected wiring and the control electrode wiring, it has generally been considered preferable for the resistance value of the Kelvin-connected wiring to be as low as possible.

[0065] Therefore, the inventors of the present invention specify a resistance value of 1 mΩ as the lower limit of the range of the resistance value of the Kelvin wiring predetermined portion Pk in the present invention when the Kelvin wiring predetermined portion Pk is an individual Kelvin wiring Wki1 to Wkin corresponding to at least one of the multiple switching elements SW1 to SWn, and specify a resistance value of 3 mΩ as the lower limit of the range of the resistance value of the Kelvin wiring predetermined portion Pk in the present invention when the Kelvin wiring predetermined portion Pk is at least a part of the common Kelvin wiring Wkc. This clearly distinguishes the present invention from the prior art. In addition, this allows the present invention to reduce "shunting" and "superimposed switching noise" compared to when only parasitic resistance exists in the Kelvin wiring. In addition, by increasing the lower limit of the range of the resistance value of the Kelvin wiring predetermined portion Pk to the above resistance value, the "shunting" and "superimposed switching noise" can be reduced more effectively as described above.

[0066] {Position of Kelvin wiring designated part Pk} The position of the Kelvin wiring predetermined portion Pk is not particularly limited. However, since the "shunt current" flows from the individual Kelvin wiring Wki1-Wkin of at least one of the switching elements SW1-SWn into the common Kelvin wiring Wkc and flows out from the individual Kelvin wiring Wki1-Wkin of at least one other switching element SW1-SWn, from the viewpoint of reliably reducing the "shunt current" and "superimposition of switching noise", it is preferable that the Kelvin wiring predetermined portion Pk is disposed in the individual Kelvin wiring Wki1-Wkin corresponding to all of the switching elements SW1-SWn, or disposed in a specific portion of the common Kelvin wiring corresponding to all of the switching elements SW1-SWn.

[0067] In addition, when the Kelvin wiring predetermined portion Pk is arranged on the individual Kelvin wiring Wki1-Wkin of all the remaining switching elements except one of the switching elements SW1-SWn, whether or not the Kelvin wiring predetermined portion Pk is arranged on the individual Kelvin wiring Wki1-Wkin corresponding to the one switching element that is removed does not have a significant effect on the current value of the "shunting". Therefore, even in a form in which the Kelvin wiring predetermined portion Pk is arranged on the individual Kelvin wiring Wki1-Wkin of all the remaining switching elements except one of the switching elements SW1-SWn, "shunting" and "superimposition of switching noise" are reduced in almost the same way as in a form in which the Kelvin wiring predetermined portion Pk is arranged on the individual Kelvin wiring Wki1-Wkin corresponding to all the switching elements SW1-SWn, and this form is also included in this preferable form.

[0068] In addition, examples of forms in which the Kelvin wiring specified portion Pk is arranged in a specific portion of the common Kelvin wiring corresponding to all switching elements SW1 to SWn include a form in which the portion in the common Kelvin wiring Wkc between a pair of locations where each of the individual Kelvin wirings Wki1 to Wkin of a pair of adjacent switching elements of all switching elements SW1 to SWn is connected is the Kelvin wiring specified portion Pk, a form in which the entire common Kelvin wiring Wkc is the Kelvin wiring specified portion Pk, and a form in which the connection points between the common Kelvin wiring Wkc and the individual Kelvin wirings Wki1 to Wkin corresponding to all switching elements SW1 to SWn and the surrounding areas are the Kelvin wiring specified portion Pk.

[0069] {Upper limit of resistance of Kelvin wiring specified part Pk} Next, the upper limit of the resistance value of the Kelvin wiring predetermined portion Pk will be described.

[0070] From the viewpoint of reducing the shunting of the main current to the Kelvin wiring Wk and the switching noise superimposed on the shunting, the resistance value of the Kelvin wiring specified part Pk is preferably as large as possible. Therefore, the theoretical upper limit of the resistance value of the Kelvin wiring specified part Pk is infinite. In other words, theoretically, there is no upper limit to the resistance value of the Kelvin wiring specified part Pk.

[0071] On the other hand, from the viewpoint of controlling the switching elements SW1 to SWn, it is necessary that the sum of the resistance value of the Kelvin wiring predetermined part Pk and the resistance value of the gate resistance Rg is equal to the recommended gate resistance value of the switching elements SW1 to SWn. However, since the recommended gate resistance value of the switching elements SW1 to SWn is specified according to the specifications (performance) of the switching elements SW1 to SWn, there is a possibility that switching elements SW1 to SWn without a recommended gate resistance value will be developed in the future. Therefore, it is unreasonable to interpret the recommended gate resistance value as a factor that restricts the upper limit of the resistance value of the Kelvin wiring predetermined part Pk. However, taking into account the current actual situation, a realistic upper limit may be set for the resistance value of the Kelvin wiring predetermined part Pk. In general, the recommended gate resistance value is several tens of Ω to several hundreds of Ω. In addition, it is necessary to consider future technological progress of the switching elements with respect to the recommended gate resistance value. In addition, the realistic upper limit of the resistance value of the Kelvin wiring predetermined part Pk may be set to, for example, 1 kΩ.

[0072] To summarize the above explanation, theoretically there is no upper limit to the resistance value of the Kelvin wiring predetermined part Pk, but in reality, it is preferable that the resistance value of the Kelvin wiring predetermined part Pk be 1 kΩ or less.

[0073] <<Increasing the resistance of the predetermined portion Pk of the Kelvin wiring>> The Kelvin wiring predetermined portion Pk may be a resistive element, which makes it possible to easily increase the resistance value of the Kelvin wiring predetermined portion Pk.

[0074] The Kelvin wiring specified portion Pk may be made of a material with high electrical resistivity. In this way, the resistance value of the Kelvin wiring specified portion Pk can be easily increased. An example of a material with high electrical resistivity is nichrome. Nichrome has a relatively small linear expansion coefficient, which is approximately the same as that of copper, and is therefore preferable as a material for the switching module 100. Incidentally, the electrical resistivity of nichrome is 1.10×10−6 [Ω·m], and the electrical resistivity of copper is 1.68×10−8 [Ω·m].

[0075] The cross-sectional area of ​​the Kelvin wiring designated portion Pk may be reduced, thereby increasing the resistance value of the Kelvin wiring designated portion Pk without changing the material.

[0076] {Operation of the first configuration example} Next, the operation of the first configuration example of the switching module 100 configured as above will be described with reference to FIG. 1A.

[0077] 1A, when a control electrode drive signal instructing "ON" is input from the control electrode drive circuit to the control wiring terminal Tc, the switching elements SW1 to SWn are turned on. Then, in each of the switching elements SW1 to SWn, a main current flows between the first electrode Ef and the second electrode Es. In this process, a part of the main current flows into the individual Kelvin wirings Wki1 to Wkin of the switching elements SW1 to SWn having a relatively high source potential and is diverted to the common Kelvin wiring Wkc, and this diverted current flows back through the individual Kelvin wirings Wki1 to Wkin of the switching elements SW1 to SWn having a relatively low source potential and merges with the main current at the individual second electrode wirings Wsi1 to Wsin corresponding to the switching elements SW1 to SWn. Then, switching noise caused by the wiring of the switching module 100 is superimposed on this diverted current. However, in the switching module 100, a Kelvin wiring predetermined portion Pk is disposed in the Kelvin wiring Wk, and this Kelvin wiring predetermined portion Pk is an individual Kelvin wiring Wki1-Wsin corresponding to at least one of the multiple switching elements SW1-SWn and has a resistance value of 1 mΩ or more, or this Kelvin wiring predetermined portion Pk is at least a part of the common Kelvin wiring Wkc and has a resistance value of 3 mΩ or more, so that the above-mentioned shunt and switching noise superimposed on the shunt are reduced by this resistance value. This reduces the deviation in the turn-on or turn-off timing of the multiple switching elements SW1-SWn from exceeding the allowable limit. {Second configuration example} The second configuration example differs from the first configuration example in the following configuration and operation, but the other configurations and operations are the same as those of the first configuration example, so only these differences will be described.

[0078] FIG. 1B is a circuit diagram illustrating an overview of a second configuration example of the switching module 100 according to an embodiment of the present disclosure.

[0079] Referring to FIG. 1B, in a second configuration example of the switching module 100, the control electrode wiring Wc includes a plurality of single control electrode wirings Wc1-Wcn. One end of each of the plurality of single control electrode wirings Wc1-Wcn is connected to a plurality of control wiring terminals Tc1-Tcn. A plurality of control electrode drive signals different from each other are input to the plurality of control wiring terminals Tc1-Tcn. This causes the plurality of switching elements SW1-SWn to operate differently from each other. In the second configuration example, the plurality of switching elements SW1-SWn are designed to turn on at predetermined, mutually different on-timings and turn off at predetermined, mutually different off-timings, and allowable limits are set for the deviation from the on-timing and the deviation from the off-timing. The second configuration example of the switching module 100 can be applied to such a switching module in which the plurality of switching elements SW1-SWn operate differently from each other.

[0080] [Specific embodiment] Next, a specific embodiment of the switching module 100 according to the embodiment of the present disclosure will be described. Below, a specific embodiment of only the first configuration example of the switching module 100 will be described, and a specific embodiment of the second configuration example of the switching module 100 will be omitted because it differs from the first configuration example only in the configuration of the control electrode wiring Wc.

[0081] {Main parts} First, the main components constituting the switching module 100 will be described. Fig. 2A is a perspective view showing the appearance of a discrete component 10 incorporating a single switching element SW, and Fig. 2B is a circuit diagram showing an equivalent circuit of the discrete component 10 in Fig. 2A. The structure of the discrete component 10 is well known, so it will be described briefly.

[0082] 2A and 2B, the discrete component 10 is a four-terminal power semiconductor and includes a resin encapsulant 5 and lead terminals 1 to 4. The resin encapsulant 5 is composed of a chip Ch incorporating a single switching element SW, wiring that electrically connects the switching element SW of the chip Ch to the lead terminals 1 to 4, and a resin body that encapsulates the chip Ch and the wiring. The single switching element SW is, for example, an NMOSFET, and includes a drain D, a source S, a gate G, and a source sense wiring SS. The drain D, the source S, the gate G, and the source sense wiring SS are connected to the lead terminals 1, 2, 3, and 4, respectively. The drain D, the source S, the gate G, and the source sense wiring SS correspond to the first electrode Ef, the second electrode Es, the control electrode Ec, and the Kelvin sense wiring KS, respectively. Note that here, a diode Di is connected between the drain and source of the NMOSFET so that its forward direction is opposite to the forward direction of the NMOSFET, and this is a body diode (parasitic diode).

[0083] FIG. 3 is a circuit diagram showing an equivalent circuit of one switching element SW of a module 20 incorporating a plurality of switching elements connected in parallel with each other, and the internal wirings 11-13 and KS related thereto. The module 20 is a four-terminal power semiconductor and includes a plurality of chips Ch. FIG. 3 shows one of the chips Ch and its related members. Referring to FIG. 3, the switching element SW of the chip Ch is, for example, an NMOSFET, and the drain D (Ef), source (Es), and gate G (Ec) are connected to a terminal (drain terminal) 1, a terminal (source terminal) 2, and a terminal (gate terminal) 3 via the internal wirings 11, 12, and 13, respectively. In addition, the source sense wiring (Kelvin sense wiring KS) is connected to a source sense terminal 4. The internal wirings 11, 12, and 13 and the Kelvin sense wiring KS have parasitic resistances R1-R4 and parasitic inductances L1-L4.

[0084] Fig. 4 is a circuit diagram showing an example of the configuration of a switching module 100A in which the first configuration example of the switching module 100 in Fig. 1A is realized using the discrete components 10 incorporating the single switching element SW in Fig. 2A and Fig. 2B. In order to facilitate understanding of the gist of the present invention, Fig. 4 shows only the configuration related to the technical features of the first configuration example of the switching module 100 in Fig. 1A.

[0085] Referring to FIG. 4, the switching module 100A is configured by mounting a plurality of discrete components 10 on a substrate. For example, a patterned first electrode wiring Wf (not shown in FIG. 4), a second electrode wiring Ws, a control electrode wiring Wc (not shown in FIG. 4), and a Kelvin wiring Wk are provided on the substrate, and a plurality of discrete components 10 are mounted on pads appropriately connected to these wirings Wf, Ws, Wc, and Wk. As a result, the terminals (lead terminals) 1 to 4 of the plurality of discrete components 10 are basically connected to the corresponding wirings Wf, Ws, Wc, and Wk, respectively. However, in the Kelvin wiring Wk, the terminals 4 of all the discrete components 10 are connected to the common Kelvin wiring Wkc by the Kelvin wiring predetermined portion Pk, respectively. Therefore, the Kelvin wiring predetermined portion Pk and the Kelvin sense wiring KS corresponding to each of the switching elements SW1 to SWn constitute the individual Kelvin wirings Wki1 to Wkin. The individual Kelvin wirings Wki1-Wkin corresponding to the multiple switching elements SW1-SWn are connected to the common Kelvin wiring Wkc with a distance between them. The terminals 2 (sources of the multiple switching elements SW1-SWn) of the multiple discrete components 10 are connected to the common second electrode wiring Wsc by the individual second electrode wirings Wsi1-Wsin, respectively. Furthermore, a first wiring terminal Tf, a second wiring terminal Ts, a control wiring terminal Tc, and a Kelvin wiring terminal Tk are appropriately provided on the substrate. The first wiring terminal Tf and the control wiring terminal Tc are omitted in FIG. 4.

[0086] The Kelvin wiring predetermined portion Pk is, for example, configured by a chip made of a resistive element. However, the Kelvin wiring predetermined portion Pk may be configured by a material with high electrical resistivity such as nichrome, or may be configured to have a smaller cross-sectional area than the cross-sectional area of ​​the common second electrode wiring Wsc.

[0087] Next, the operation of the switching module 100A configured as above will be described.

[0088] 2A and 4, when a control electrode drive signal instructing "ON" is input from the control electrode drive circuit to the control wiring terminal Tc, the switching elements SW1 to SWn are turned on, and a main current Im flows between the drain D (Ef) and the source S (Es) of each of the switching elements SW1 to SWn. Here, it is assumed that the source potentials of the switching elements SW1 to SWn decrease in this order. In this process, a part of the main current Im flows into the individual Kelvin wires Wki1 to Wkir of the switching elements SW1 to SWr (r is an integer of 2 or more and n-1 or less) having a relatively high source potential, and is diverted to the common Kelvin wire Wkc, and this diverted current flows backward through the individual Kelvin wires Wkir+1 to Wkin of the switching elements SWr+1 to SWn having a relatively low source potential, and merges with the main current at the individual second electrode wires Wsir+1 to Wsin corresponding to the switching elements SWr+1 to SWn. Then, switching noise caused by the wiring of the switching module 100 is superimposed on this shunt current.

[0089] However, since the Kelvin wiring predetermined portion Pk has a resistance value of 1 mΩ or more, the shunt Ik and the switching noise superimposed on the shunt Ik are reduced by this resistance value, and thus the timing deviation of the switching of the switching elements SW1 to SWn is prevented from exceeding the allowable limit. Moreover, since the Kelvin wiring predetermined portion Pk is provided on all the individual Kelvin wirings Wki1 to Wkin, the "shunt" and the "superimposed switching noise" are efficiently reduced. Furthermore, since the terminal 4 of the Kelvin wiring of the discrete component 10 and the common Kelvin wiring Wkc are connected by the Kelvin wiring predetermined portion Pk, a general-purpose discrete component 10 can be used. In this case, one or both of the Kelvin sense wiring KS (source sense wiring SS) and the terminal 4 in the discrete component 10 may be the Kelvin wiring predetermined portion Pk. In this case, the discrete component 10 becomes a dedicated component.

[0090] Fig. 5 is a circuit diagram showing an example of the configuration of a switching module 100B in which the first configuration example of the switching module 100 in Fig. 1A is realized using a module 20 incorporating a plurality of switching elements SW connected in parallel to each other in Fig. 3. In order to facilitate understanding of the gist of the present invention, Fig. 5 shows only the configuration related to the technical features of the first configuration example of the switching module 100 in Fig. 1A.

[0091] 5, the switching module 100B is configured by mounting the module 20 on a base member 40 (see FIG. 10). For example, the base is provided with a first electrode wiring Wf (omitted in FIG. 5), a second electrode wiring Ws, a control electrode wiring Wc (omitted in FIG. 5), and a Kelvin wiring Wk, and the module 20 is mounted so as to be appropriately connected to these wirings Wf, Ws, Wc, and Wk. As a result, the terminals 1 to 4 of the module 20 are basically connected to the corresponding wirings Wf, Ws, Wc, and Wk, respectively. However, in the Kelvin wiring Wk, the terminal 4 of each chip Ch (see FIG. 3) of the module 20 is connected to the common Kelvin wiring Wkc by a predetermined wiring. Therefore, the predetermined wiring corresponding to each switching element SW1 to SWn and the Kelvin sense wiring KS constitute the individual Kelvin wirings Wki1 to Wkin. The individual Kelvin wires Wki1-Wkin corresponding to each of the switching elements SW1-SWn are connected to a common Kelvin wire Wkc with a gap between them. A Kelvin wire specific portion Pk is provided in the common Kelvin wire Wkc between a pair of locations where the individual Kelvin wires Wki1-Wkin of each pair of adjacent switching elements among all of the switching elements SW1-SWn are connected (a common Kelvin wire specific portion).

[0092] The source terminals 2 of the switching elements SW1 to SWn are connected to the common second electrode wiring Wsc by the individual second electrode wirings Wsi1 to Wsin, respectively. Furthermore, the first wiring terminal Tf, the second wiring terminal Ts, the control wiring terminal Tc, and the Kelvin wiring terminal Tk are appropriately provided on the base member 40. The first wiring terminal Tf and the control wiring terminal Tc are omitted in FIG. 5.

[0093] Next, the operation of the switching module 100B configured as above will be described.

[0094] 3 and 5, when a control electrode drive signal instructing "ON" is input from the control electrode drive circuit to the control wiring terminal Tc, the switching elements SW1 to SWn are turned on, and a main current Im flows between the drain D (Ef) and the source S (Es) of each of the switching elements SW1 to SWn. Here, it is assumed that the source potentials of the switching elements SW1 to SWn decrease in this order. A part of the main current Im flows into the individual Kelvin wires Wki1 to Wkir of the switching elements SW1 to SWr (r is an integer of 2 or more and n-1 or less) having a relatively high source potential, and is diverted to the common Kelvin wire Wkc, and this diverted current flows backward through the individual Kelvin wires Wkir+1 to Wkin of the switching elements SWr+1 to SWn having a relatively low source potential, and merges with the main current at the individual second electrode wires Wsir+1 to Wsin corresponding to the switching elements SWr+1 to SWn. Then, switching noise caused by the wiring of the switching module 100B is superimposed on this shunt current Ik.

[0095] However, since the resistance value of the Kelvin wiring specific portion Pk is 3 mΩ or more, this high resistance value reduces the shunt current Ik and the switching noise superimposed on the shunt current Ik, thereby reducing the deviation in the switching timing of the multiple switching elements SW1 to SWn from exceeding the allowable limit. Moreover, since the Kelvin wiring specific portion Pk is provided in the common Kelvin wiring specific portion corresponding to all the switching elements SW1 to SWn in the common Kelvin wiring Wkc, the "shunt current" and the "superimposed switching noise" are efficiently reduced. In addition, since the Kelvin wiring specific portion Pk is provided outside the module 20, a general-purpose module 20 can be used. In this case, the Kelvin wiring Wk having the Kelvin wiring specific portion Pk may be provided inside the module 20. In this case, the module 20 becomes a dedicated part.

[0096] [simulation] Regarding the arrangement and resistance value of the Kelvin wiring predetermined portion Pk, first and second simulations were performed.

[0097] <First simulation> In the first simulation, in the switching module 100C, Kelvin wire predetermined parts Pk were arranged in the individual Kelvin wires corresponding to all switching elements, and the resistance value of the Kelvin wire predetermined parts Pk was changed.

[0098] 6 is a circuit diagram showing an equivalent circuit of the switching module 100C in the first simulation. This simulation was performed on a full-bridge current resonant circuit in which one of a pair of high-side switching modules is configured with the switching module 100C of the present invention. For this full-bridge current resonant circuit, the power supply voltage was set to DC 500V, the inductance of the load coil was set to 800nH, and the capacitance of the load capacitor was set to 300nF.

[0099] 6, the switching module 100C includes first to third switching elements UH1 to UH3 each composed of an NMOSFET. In the switching module 100C, the drain wiring (first electrode wiring), source wiring (second electrode wiring), gate wiring (control electrode wiring), and Kelvin wiring corresponding to the first to third switching elements UH1 to UH3 are set to the same parasitic impedance. Therefore, in this switching module 100C, it is assumed that the source potentials of the first switching element UH1, the second switching element UH2, and the third switching element UH3 decrease in this order (the source potential of the third switching element UH3 is the lowest).

[0100] In this simulation, the resistance value Rtest of resistors R8, R10, and R12 enclosed by the dotted rectangle of the individual Kelvin wiring of each of the first to third switching elements UH1 to UH3 was changed as a parameter to the resistance value of the parasitic resistance (100μΩ), 10 times (1mΩ), 20 times (2mΩ), 40 times (4mΩ), 100 times (10mΩ), 200 times (20mΩ), 500 times (50mΩ), and 1000 times (100mΩ). Regarding the current of the individual Kelvin wiring, the current in the direction from the source to the common Kelvin wiring is treated as a positive current.

[0101] For the full-bridge current resonant circuit configured in this manner, the operation in the periods before and after the first to third switching elements UH1 to UH3 were turned on was simulated, and the current values ​​of the individual Kelvin wiring were obtained.

[0102] Simulation results FIG. 7 is a graph showing current values ​​in the individual Kelvin wires in a simulation using the equivalent circuit of FIG. 6. Note that FIG. 7 was created by tracing an image of an actually obtained waveform of current, and therefore the waveforms are not strictly accurate. In FIG. 7, the horizontal axis represents the elapsed time (unit: μS) of the simulation, and the vertical axis represents the current (unit: A). Also, the solid line, dashed line, and dotted line represent the current in the individual Kelvin wire of the first switching element UH1, the current in the individual Kelvin wire of the second switching element UH2, and the current in the individual Kelvin wire of the third switching element UH3, respectively.

[0103] 7, reference symbols ISS1a to ISS1h of solid curves indicate currents in the individual Kelvin wires of the first switching element UH1, reference symbols ISS2a to ISS2h of dashed curves indicate currents in the individual Kelvin wires of the second switching element UH2, and reference symbols ISS3a to ISS3h of dotted curves indicate currents in the individual Kelvin wires of the third switching element UH3. The subscripts a to h of these reference symbols indicate that the curves corresponding to the subscripts represent currents when the resistance of the individual Kelvin wires is the resistance of the parasitic resistance (100μΩ), 10 times (1mΩ), 20 times (2mΩ), 40 times (4mΩ), 100 times (10mΩ), 200 times (20mΩ), 500 times (50mΩ), and 1000 times (100mΩ), respectively. Moreover, to on the horizontal axis indicates the time when the first to third switching elements UH1 to UH3 are turned on (hereinafter, may be simply referred to as "turn on").

[0104] {The occurrence of "divergence"} 7, the currents ISS1a to ISS1h in the individual Kelvin wires of the first switching element UH1 flow in the positive direction almost immediately after the element is turned on. The currents ISS2a to ISS2h in the individual Kelvin wires of the second switching element UH2 flow in the positive direction a while after the element is turned on. The magnitude of the currents ISS2a to ISS2h in the individual Kelvin wires of the second switching element UH2 is smaller than the currents ISS1a to ISS1h in the individual Kelvin wires of the first switching element UH1. The currents ISS3a to ISS3h in the individual Kelvin wires of the third switching element UH3 flow in the reverse direction almost immediately after the element is turned on. Furthermore, the absolute value of the sum of the current values ​​of the currents ISS1a to ISS1h in the individual Kelvin wires of the first switching element UH1 and the current values ​​of the currents ISS2a to ISS2h in the individual Kelvin wires of the second switching element UH2 is generally equal to the absolute value of the current values ​​of the currents ISS3a to ISS3h in the individual Kelvin wires of the third switching element UH3. From these results, it is presumed that the currents ISS1a-ISS1h in the individual Kelvin wiring of the first switching element UH1 and the currents ISS2a-ISS2h in the individual Kelvin wiring of the second switching element UH2 flow into the common Kelvin wiring and flow out from the individual Kelvin wiring of the third switching element UH3. It is also presumed that the source potentials of the first switching element UH1, the second switching element UH2, and the third switching element UH3 decrease in descending order (the source potential of the third switching element UH3 is the lowest). From these findings, it is presumed that "shunting" has occurred.

[0105] {Superimposition of switching noise} Furthermore, the currents ISS1a-ISS1h in the individual Kelvin wires of the first switching element UH1 and the currents ISS3a-ISS3h in the individual Kelvin wires of the third switching element UH3 increase while fluctuating when turned on, and then gradually decrease. From this result, it is estimated that switching noise caused by wiring parasitic impedance is superimposed particularly on the currents ISS1a-ISS1h in the individual Kelvin wires of the first switching element UH1 and the currents ISS3a-ISS3h in the individual Kelvin wires of the third switching element UH3, which greatly fluctuates the currents ISS1a-ISS1h in the individual Kelvin wires of the first switching element UH1 and the currents ISS3a-ISS3h in the individual Kelvin wires of the third switching element UH3. Furthermore, when large fluctuations in the currents ISS1a to ISS1h in the individual Kelvin wiring of the first switching element UH1 and the currents ISS3a to ISS3h in the individual Kelvin wiring of the third switching element UH3 are combined with various adverse conditions, it is estimated that this will cause the timing deviation of the switching of the first to third switching elements UH1 to UH3 to exceed the tolerable limit.

[0106] {Effect of increasing resistance of individual Kelvin wiring} Next, when attention is paid to the resistance value of the individual Kelvin wire, as the resistance value of the individual Kelvin wire increases, the fluctuation in the current of the individual Kelvin wire monotonically decreases.

[0107] When the resistance value of the individual Kelvin wire is the resistance value of the parasitic resistance (100 μΩ), the fluctuations in the current ISS1a in the individual Kelvin wire of the first switching element UH1 and the current ISS3a in the individual Kelvin wire of the third switching element UH3 are of a reasonable magnitude. On the other hand, when the resistance value of the individual Kelvin wire is 10 times (1 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1b in the individual Kelvin wire of the first switching element UH1 and the current ISS3b in the individual Kelvin wire of the third switching element UH3 are clearly smaller than those when the resistance value of the individual Kelvin wire is the resistance value of the parasitic resistance (100 μΩ).

[0108] When the resistance value of the individual Kelvin wiring is 40 times (4 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1d of the individual Kelvin wiring of the first switching element UH1 and the current ISS3d of the individual Kelvin wiring of the third switching element UH3 are effectively reduced compared to when the resistance value of the individual Kelvin wiring is the resistance value of the parasitic resistance (100 μΩ).

[0109] When the resistance value of the individual Kelvin wiring is 100 times (10 mΩ) the resistance value of the parasitic resistance, the fluctuations of the current ISS1e of the individual Kelvin wiring of the first switching element UH1 and the current ISS3e of the individual Kelvin wiring of the third switching element UH3 are significantly reduced compared to when the resistance value of the individual Kelvin wiring is the resistance value of the parasitic resistance (100 μΩ).

[0110] When the resistance value of the individual Kelvin wiring is 1000 times (100 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1h of the individual Kelvin wiring of the first switching element UH1 and the current ISS3h of the individual Kelvin wiring of the third switching element UH3 are significantly reduced compared to when the resistance value of the individual Kelvin wiring is the resistance value of the parasitic resistance (100 μΩ).

[0111] {summary} First, providing the Kelvin wiring predetermined portion Pk in the individual Kelvin wiring corresponding to all the switching elements UH1 to UH3 is effective as a measure to reduce "shunting" and "superimposed switching noise". Second, in this simulation, the number of switching elements was three, but it is presumed that the same effect can be obtained even if the number of switching elements is four or more. Third, if the resistance value of the individual Kelvin wiring is 10 times (1 mΩ) or more the resistance value of the parasitic resistance, the "shunting" and "superimposed switching noise" are reduced to a degree that can be clearly distinguished from the case where the resistance value of the individual Kelvin wiring is the resistance value of the parasitic resistance (100 μΩ).

[0112] <Second Simulation> In the second simulation, in the switching module 100D, a portion of the common Kelvin wiring corresponding to all switching elements UH1 to UH3 between a pair of locations where the individual Kelvin wiring of each pair of adjacent switching elements is connected (a common Kelvin wiring specific portion) was determined as a Kelvin wiring specified portion Pk, and the resistance value of the common Kelvin wiring specific portion was changed.

[0113] 8 is a circuit diagram showing an equivalent circuit of the switching module 100D in the second simulation. This simulation was performed on a full-bridge current resonant circuit configured and set in the same manner as in the first simulation.

[0114] 8, in this switching module 100D, the resistors R9 and R11 (resistances of the specific part of the common Kelvin wiring) surrounded by a dotted rectangle of the common Kelvin wiring are set as the Kelvin wiring specific part Pk. The resistors R8, R10, and R12 of the individual Kelvin wirings of the first to third switching elements UH1 to UH3 are set to 100 μΩ, which is the resistance value of the parasitic resistance. Other than this, it is the same as the switching module 100C of FIG. 6.

[0115] For this switching module 100D, a simulation was performed by changing the resistance value Rtest as a parameter to the resistance value of the parasitic resistance (300 μΩ), 333 times that (100 mΩ), and 1000 times that (300 mΩ), and the current values ​​of the individual Kelvin wiring in the periods before and after the first to third switching elements UH1 to UH3 were turned on were obtained.

[0116] Simulation results FIG. 9 is a graph showing current values ​​of the individual Kelvin wiring in a simulation using the equivalent circuit of FIG. 8. Note that FIG. 9 was created by tracing an image of a waveform of a current that was actually obtained, and therefore the waveforms are not strictly accurate. In FIG. 9, the horizontal axis represents the elapsed time (unit: μS) of the simulation, and the vertical axis represents the current (unit: A). Also, the solid line, the dashed line, and the dotted line represent the current of the individual Kelvin wiring of the first switching element UH1, the current of the individual Kelvin wiring of the second switching element UH2, and the current of the individual Kelvin wiring of the third switching element UH3, respectively. In FIG. 9, the reference symbols ISS1i to ISS1k of the solid curves indicate the current of the individual Kelvin wiring of the first switching element UH1, the reference symbols ISS2i to ISS2k of the dashed curves indicate the current of the individual Kelvin wiring of the second switching element UH2, and the reference symbols ISS3i to ISS3k of the dotted curves indicate the current of the individual Kelvin wiring of the third switching element UH3. The subscripts i to k in these reference symbols indicate that the curves corresponding to the subscripts represent the currents when the resistance of a specific portion of the common Kelvin wiring is the resistance of the parasitic resistance (300 μΩ), 333 times that resistance (100 mΩ), and 1000 times that resistance (300 mΩ), respectively. Also, to on the horizontal axis indicates the turn-on time.

[0117] 9, as can be seen at a glance, the occurrence of "shunting" of the currents in the individual Kelvin wires of the first to third switching elements UH1 to UH3, the "superimposition of switching noise," and the reduction in the fluctuation of the currents in the individual Kelvin wires in response to an increase in the resistance value of the individual Kelvin wires are the same as those in FIG 7. Therefore, a description thereof will be omitted.

[0118] {Effect of increased resistance in specific parts of the common Kelvin wiring} When the resistance value of a specific portion of the common Kelvin wire is the resistance value of the parasitic resistance (300 μΩ), as in FIG. 7, the fluctuations in the current ISS1i of the individual Kelvin wire of the first switching element UH1 and the current ISS3i of the individual Kelvin wire of the third switching element UH3 are of a certain magnitude.

[0119] On the other hand, when the resistance value of the specific portion of the common Kelvin wiring is 333 times (100 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1j of the individual Kelvin wiring of the first switching element UH1 and the current ISS3j of the individual Kelvin wiring of the third switching element UH3 are significantly reduced compared to when the resistance value of the specific portion of the common Kelvin wiring is the resistance value of the parasitic resistance (300 μΩ).

[0120] When the resistance value of the specific portion of the common Kelvin wiring is 1000 times (300 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1k of the individual Kelvin wiring of the first switching element UH1 and the current ISS3k of the individual Kelvin wiring of the third switching element UH3 are significantly reduced compared to when the resistance value of the specific portion of the common Kelvin wiring is the resistance value of the parasitic resistance (300 μΩ).

[0121] Although not shown in Figure 9, it was confirmed that when the resistance value of the specific portion of the common Kelvin wiring is 10 times (3 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1 of the individual Kelvin wiring of the first switching element UH1 and the current ISS3 of the individual Kelvin wiring of the third switching element UH3 are clearly smaller than those when the resistance value of the specific portion of the common Kelvin wiring is the resistance value of the parasitic resistance (300 μΩ).

[0122] Furthermore, from the above results, it is estimated that when the resistance value of the specific portion of the common Kelvin wiring is 40 times (12 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1 of the individual Kelvin wiring of the first switching element UH1 and the current ISS3 of the individual Kelvin wiring of the third switching element UH3 are significantly reduced compared to when the resistance value of the specific portion of the common Kelvin wiring is the resistance value of the parasitic resistance (300 μΩ).

[0123] Furthermore, from the above results, it is estimated that when the resistance value of the specific portion of the common Kelvin wiring is 100 times (30 mΩ) the resistance value of the parasitic resistance, the fluctuations in the current ISS1 of the individual Kelvin wiring of the first switching element UH1 and the current ISS3 of the individual Kelvin wiring of the third switching element UH3 are significantly reduced compared to when the resistance value of the specific portion of the common Kelvin wiring is the resistance value of the parasitic resistance (300 μΩ).

[0124] {summary} First, providing the Kelvin wiring specific portion Pk in the common Kelvin wiring specific portion corresponding to all the switching elements UH1 to UH3 is more effective as a measure to reduce "shunting" and "superimposed switching noise" than providing the Kelvin wiring specific portion Pk in the individual Kelvin wiring corresponding to all the switching elements UH1 to UH3. Second, in this simulation, the number of switching elements was three, but it is presumed that the same effect can be obtained even if the number of switching elements is four or more. Third, if the resistance value of the common Kelvin wiring specific portion is 10 times (3 mΩ) or more the resistance value of the parasitic resistance, the "shunting" and "superimposed switching noise" are reduced to a degree that can be clearly distinguished from the case where the resistance value of the common Kelvin wiring specific portion is the resistance value of the parasitic resistance (100 μΩ).

[0125] [Switching module installation status] FIG. 10 is a diagram illustrating the external appearance of a full-bridge current resonant circuit 1000 in which the switching module 100 of FIG. 1A is used as a high-side switching module 100. In FIG.

[0126] 10, in a full-bridge current resonant circuit 1000, the switching module 100 in FIG. 1A is used as a high-side switching module 100. A low-side switching module 300 is configured as a switching module to which the present invention is not applied. The full-bridge current resonant circuit 1000 includes a base member 40. A module 20 including chips Ch of switching elements SW1 to SW3 is embedded in this base member 40. Three pads corresponding to the switching elements SW1 to SW3 are formed on the upper surface of this module 20. Individual second electrode wirings Wsi1 to Wsi3 corresponding to the three switching elements SW1 to SW3 are connected to these pads, and these individual second electrode wirings Wsi1 to Wsi3 are connected to the tip of a common second electrode wiring Wsc, and an SHDL terminal (second wiring terminal Ts) is connected to the base end of the common second electrode wiring Wsc. The individual second electrode wirings Wsi1 to Wsi3, the common second electrode wiring Wsc, and the SHDL terminal are integrated and configured as a single member. A common Kelvin wiring Wkc is provided on the base member 40 so as to run along the three pads, and the three pads and the common Kelvin wiring Wkc are connected by individual Kelvin wirings Wki1 to Wki3. Of these individual Kelvin wirings Wki1 to Wki3n, the individual Kelvin wiring Wki1 corresponding to the first switching element SW1 is configured as the Kelvin wiring predetermined portion Pk. When the Kelvin wiring predetermined portion Pk is configured with a chip of a resistive element, the chip is disposed in this portion. The base end of the common Kelvin wiring Wkc is connected to the SSH terminal (Kelvin wiring terminal Tk). The first electrode wiring Wf is provided so as to be located below the chips of the switching elements SW1 to SW3, and is connected to the DH terminal (first wiring terminal Tf). In addition, a control electrode wiring Wc is provided on the base member 40 so as to be connected to the three pads. The base end of the control electrode wiring Wc is connected to the GH terminal (control wiring terminal Tc). Note that reference symbols SL, GL, and SSL respectively denote the source wiring terminal (second wiring terminal), the gate wiring terminal (control wiring terminal), and the source sense wiring terminal (Kelvin wiring terminal) of the low-side switching module 300.In this manner, when the switching module 100 of FIG. 1A is mounted, the resistance of the Kelvin wiring predetermined portion Pk can be easily increased.

[0127] (Other embodiments) The second configuration example may be configured as a switching module embodied by using discrete components 10 or modules 20 as shown in FIG. 4 or FIG.

[0128] In a switching module 100A that embodies the discrete component 10 of FIG. 4, the Kelvin wiring predetermined portion Pk may be provided on the common Kelvin wiring Wkc as shown in FIG.

[0129] In a switching module 100B embodied using the module 20 of FIG. 5, the Kelvin wiring predetermined portion Pk may be provided in the individual Kelvin wirings Wki1 to Wkin as shown in FIG.

[0130] In the switching module 100A of FIG. 4, the Kelvin wiring predetermined portion Pk may be disposed on the individual Kelvin wirings Wki1 to Wkin of all the remaining switching elements except for one of the switching elements SW1 to SWn.

[0131] Numerous modifications and other embodiments will be apparent to those skilled in the art in light of the above description, and therefore the above description is to be construed as illustrative only. [Industrial Applicability]

[0132] The switching module of the present invention has Kelvin-connected wiring and is equipped with a plurality of switching elements connected in parallel with each other, and is useful as a switching module capable of reducing the deviation in the timing of turning on or off the switching elements from exceeding an allowable limit. [Explanation of symbols]

[0133] Terminals 1 to 4 5 Resin sealing body 10 Discrete Components 11~13 Internal wiring 20 Modules 40 Base material 100, 100A, 100B, 100C, 100D Switching Module 1000 Full-bridge current resonant circuit Ec control electrode Ef 1st electrode Es 2nd electrode KS Kelvin sense wiring Pk Kelvin wiring designated part SW, SW1 to SWn switching elements Tc control wiring terminal Tf 1st wiring terminal Tk Kelvin wiring terminal Ts 2nd wiring terminal Wc Control electrode wiring Wf 1st wiring terminal Wfc Common 1st wiring terminal Wfi1~Wfin Individual 1st wiring terminal Wk Kelvin wiring Wkc Common Kelvin Wiring Wki1~Wkin individual Kelvin wiring Ws 2nd electrode wiring Wsc Common second electrode wiring Wsi1~Wsin Individual second electrode wiring

Claims

1. A switching module in which a plurality of switching elements are connected in parallel, a plurality of switching elements each having a first electrode, a second electrode, and a control electrode for controlling a main current flowing between the first electrode and the second electrode depending on a potential difference with respect to the second electrode; a first electrode wiring electrically connected to the first electrode of each of the plurality of switching elements; second electrode wiring electrically connected to the second electrodes of the plurality of switching elements; a control electrode wiring electrically connected to the control electrode of each of the plurality of switching elements; a common Kelvin wiring and an individual Kelvin wiring that electrically connects the common Kelvin wiring to the second electrodes of the plurality of switching elements; A switching module, wherein a predetermined portion of the Kelvin wiring, which is at least a part of the Kelvin wiring, is an individual Kelvin wiring corresponding to at least one of the plurality of switching elements and has a resistance value of 1 mΩ or more, or the predetermined portion of the Kelvin wiring is at least a part of the common Kelvin wiring and has a resistance value of 3 mΩ or more.

2. 2. The switching module of claim 1, wherein the plurality of switching elements are n (n is an integer greater than or equal to 2) switching elements, and the predetermined portion of the Kelvin wiring is the individual Kelvin wiring corresponding to n or n-1 of the switching elements.

3. 3. The switching module according to claim 2, wherein the predetermined portion of the Kelvin wiring has a resistance value of 4 mΩ or more.

4. 3. The switching module according to claim 2, wherein the predetermined portion of the Kelvin wiring has a resistance value of 10 mΩ or more.

5. 3. The switching module according to claim 2, wherein the predetermined portion of the Kelvin wiring has a resistance value of 100 mΩ or more.

6. the common Kelvin wiring extends to have both ends; The individual Kelvin lines corresponding to the plurality of switching elements are electrically connected to the common Kelvin line at intervals from one another, and 2. The switching module according to claim 1, wherein the predetermined portion of the Kelvin wiring is a portion of the common Kelvin wiring corresponding to all of the switching elements, between a pair of locations where the individual Kelvin wirings of each of a pair of adjacent switching elements are connected.

7. 7. The switching module according to claim 6, wherein the predetermined portion of the Kelvin wiring has a resistance value of 12 mΩ or more.

8. 7. The switching module according to claim 6, wherein the predetermined portion of the Kelvin wiring has a resistance value of 30 mΩ or more.

9. 7. The switching module according to claim 6, wherein the predetermined portion of the Kelvin wiring has a resistance value of 300 mΩ or more.

10. 2. The switching module according to claim 1, wherein the sum of the resistance value of the predetermined portion of the Kelvin wiring and the resistance value of a control electrode resistor arranged on the control electrode wiring of the switching element corresponding to the predetermined portion of the Kelvin wiring is the recommended gate resistance value of the switching element.

11. 2. The switching module according to claim 1, wherein the predetermined portion of the Kelvin wiring has a resistance value of 1 kΩ or less.

12. 2. The switching module according to claim 1, wherein the control electrode wiring includes a common control electrode wiring having one end connected to a control wiring terminal and the other end terminated, and individual control electrode wiring electrically connecting the common control electrode wiring to the control electrodes of each of the plurality of switching elements.

13. 2. The switching module according to claim 1, wherein the control electrode wiring includes a plurality of single control electrode wirings, each having one end connected to a respective one of a plurality of control wiring terminals and each having the other end electrically connected to a respective one of the control electrodes of the plurality of switching elements.

14. 14. The switching module according to claim 1, wherein the switching elements are IGBTs, field effect transistors or bipolar transistors.

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