Power module

Abstract

Power module comprising: a number N of semiconductor modules (10.1-10. n); a number M of connection plates (20.1-20. m); wherein N> = 1; wherein M> = N + 1. Each semiconductor module (10. k) is interposed between a respective pair of connection plates (20.1-20. m) including a first connection plate (20.j) and a second connection plate (20.j+ 1), arranged on opposite sides of said semiconductor module (10. k). Each semiconductor module (10. k) is in contact with the respective pair of connection plates, so that the semiconductor module (10. k) is in galvanic contact with the first connection plate (20.j) on one side and exchanges heat with said first connection plate (20.j), and is in galvanic contact with the second connection plate 20.j + 1) on the other side and exchanges heat with said second connection plate (20.j + 1). Each semiconductor module (10.1-10. n) comprises: a first and a second connection wall (12, 13) made of electrically and thermally conductive material; a semiconductor device (11), interposed between said first and second connection walls, and constituting a controlled switching element, said semiconductor device (11) having a first face (11a) in contact with the first connection wall (12) and a second face (11b) in contact with the second connection wall (13). Each connection plate (20.1-20. m) comprises: a box-shaped body (25) having at least one given face in contact with either the first or the second connection wall (12, 13) of one of said N semiconductor modules (10.1-10. n). Said box-shaped body (25) comprises at least one primary duct (22) and one secondary duct (23). Said primary duct (22) and said secondary duct (23) extend prevalently parallel to said given face. Said power module (100) further comprises a hydraulic device (130) in fluidic communication with the primary and secondary ducts (22, 23) of each one of said connection plates (20.1-20. m), and configured to promote a flow of a heat transfer fluid in the primary duct (22) and in the secondary duct (23) of each one of said connection plates (20.1-20. m). Said power module (100) further comprises a hydraulic connector (120) that connects said connection plates (20.1- 20. m) to each other. Said hydraulic connector (120) is functionally coupled to said hydraulic device (130) so that, in at least one of said M connection plates, the fluid flows in the primary duct (22) and, before flowing in the secondary duct (23), flows through at least another one of said M connection plates (20.1-20. m).

Description

[0001] POWER MODULE

[0002] Field of the invention

[0003] The present invention relates to the field of power electronics. In particular, the present invention concerns a power module.

[0004] Background art

[0005] Nowadays, most energy is consumed in the form of electric energy. Power electronics plays a fundamental role in the electric-energy generation, storage, distribution, conversion and consumption cycle.

[0006] In particular, a significant part of energy losses can be attributed to power electronics converters dissipating energy in operation, e.g. in the form of heat.

[0007] An increase in the temperature of the components of a converter results in performance degradation, which is typically proportional to temperature, as well as in the risk of irreversible failure of such components, all of which have a maximum operating temperature.

[0008] The Applicant also observed that the continual heating / cooling cycles of power devices significantly contribute to decreasing their service life and reliability.

[0009] In order to reduce failures and / or losses due to the thermal dynamics of such devices, heat sinking systems are commonly used in association with converters.

[0010] The Applicant observed that efficient heat sinking systems are very expensive.

[0011] Furthermore, the Applicant observed that, disadvantageously, heat sinking systems cause an increase in the converter's volume and / or weight, thus reducing the converter's volumetric and gravimetric power density. Summary of the invention The Applicant perceived the need to provide a power electronics device with a higher level of integration and a higher power density.

[0012] In accordance with a first aspect, the invention relates to a power module.

[0013] Preferably, said power module comprises a number N of semiconductor modules.

[0014] Preferably, said power module comprises a number M of connection plates.

[0015] Preferably, N> = 1.

[0016] Preferably, M> = N + 1.

[0017] Preferably, each semiconductor module is interposed between a respective pair of connection plates including a first connection plate and a second connection plate.

[0018] Preferably, said first connection plate and second connection plate are arranged on opposite sides of said semiconductor module.

[0019] Preferably, each semiconductor module is in contact with the respective pair of connection plates.

[0020] Preferably, the semiconductor module is in galvanic contact with the first connection plate on one side.

[0021] Preferably, the semiconductor module exchanges heat with said first connection plate on one side.

[0022] Preferably, the semiconductor module is in galvanic contact with the second connection plate on the other side.

[0023] Preferably, the semiconductor module exchanges heat with said second connection plate on the other side.

[0024] Preferably, each semiconductor module comprises a first connection wall. Preferably, the first connection wall is made of electrically and thermally insulating material.

[0025] Preferably, each semiconductor module comprises a second connection wall. Preferably, the second connection wall is made of electrically and thermally insulating material.

[0026] Preferably, each semiconductor module comprises a semiconductor device.

[0027] Preferably, said semiconductor device is interposed between said first and second connection walls.

[0028] Preferably, said semiconductor device constitutes a controlled switching element.

[0029] Preferably, said semiconductor device has a first face in contact with the first connection wall.

[0030] Preferably, said semiconductor device has a second face in contact with the second connection wall.

[0031] Preferably, each connection plate comprises a box-shaped body.

[0032] Preferably, said box-shaped body has at least one face in contact with either the first or the second connection wall of one of said N semiconductor modules.

[0033] Preferably, said box-shaped body comprises at least one primary duct. Preferably, said box-shaped body comprises a secondary duct.

[0034] Preferably, said primary duct extends prevalently parallel to said given face.

[0035] Preferably, said secondary duct extends prevalently parallel to said given face.

[0036] Preferably, said power module comprises a hydraulic device.

[0037] Preferably, said hydraulic device is in fluidic communication with the primary duct of each one of said connection plates.

[0038] Preferably, said hydraulic device is in fluidic communication with the secondary duct of each one of said connection plates.

[0039] Preferably, said hydraulic device is configured to promote a flow of a heat transfer fluid in the primary duct of each one of said connection plates.

[0040] Preferably, said hydraulic device is configured to promote a flow of a heat transfer fluid in the secondary duct of each one of said connection plates. Preferably, said power module comprises a hydraulic connector.

[0041] Preferably, said hydraulic connector connects said connection plates to each other.

[0042] Preferably, said hydraulic connector is functionally coupled to said hydraulic device so that, in at least one of said M connection plates, the fluid flows in the primary duct and, before flowing in the secondary duct, flows through at least another one of said M connection plates.

[0043] In accordance with some preferred embodiments of the invention, said power module comprises one or more of the following preferred features. Preferably, in at least M-l connection plates, the fluid flows in the primary duct and, before flowing in the secondary duct, flows through at least another one of said M connection plates.

[0044] Preferably, in each one of said M-l connection plates, the primary duct has an inlet mouth, through which the heat transfer fluid enters.

[0045] Preferably, in each one of said M-l connection plates, the primary duct has an outlet mouth.

[0046] Preferably, in each one of said M-l connection plates, the heat transfer fluid exits through the outlet mouth of said primary duct to flow into another connection plate.

[0047] Preferably, in each one of said M-l connection plates, the secondary duct has an inlet mouth.

[0048] Preferably, in each one of said M-l connection plates, the heat transfer fluid coming from another connection plate enters through the inlet mouth of said secondary duct.

[0049] Preferably, in each one of said M-l connection plates, the secondary duct has an outlet mouth, through which the heat transfer fluid exits.

[0050] Preferably, in a connection plate not belonging to said M-l connection plates, the fluid exiting the primary duct enters the secondary duct without flowing through any other connection plate. Preferably, said M connection plates comprise a main connection plate. Preferably, said main connection plate has an inlet.

[0051] Preferably, the inlet of said main connection plate receives the heat transfer fluid from said hydraulic device.

[0052] Preferably, said main connection plate has an outlet.

[0053] Preferably, from the outlet of said main connection plate, said heat transfer fluid returns to said hydraulic device.

[0054] Preferably, from the outlet of said main connection plate, said heat transfer fluid returns to said hydraulic device after having flowed through all the other connection plates via said hydraulic connector.

[0055] Preferably, in said main connection plate, said inlet is defined by an inlet mouth of the primary duct of said main connection plate.

[0056] Preferably, in said main connection plate, said outlet is defined by an outlet mouth of the secondary duct of said main connection plate.

[0057] Preferably, said inlet and said outlet are located on one same face of said main connection plate.

[0058] Preferably, said M connection plates are arranged in succession, from an initial connection plate to a final connection plate.

[0059] Preferably, said heat transfer fluid enters the initial connection plate. Preferably, after having entered the initial connection plate, said heat transfer fluid flows through all connection plates in succession up to the final connection plate.

[0060] Preferably, after having flowed through all connection plates in succession up to the final connection plate, said heat transfer fluid flows again through all connection plates from the final connection plate to the initial connection plate.

[0061] Preferably, the initial connection plate is the main connection plate. Preferably, said heat transfer fluid coming from said hydraulic device first flows through the primary ducts of all M connection plates, and then flows through the secondary ducts of all M connection plates. Preferably, after having flowed first through the primary ducts of all M connection plates and then through the secondary ducts of all M connection plates, said heat transfer fluid returns to said hydraulic device.

[0062] Preferably, said semiconductor device has, in a plan view, an area which is smaller than that of said first connection wall.

[0063] Preferably, said semiconductor device has, in a plan view, an area which is smaller than that of said second connection wall.

[0064] Preferably, each semiconductor module comprises an insulating material. Preferably, said insulating material is interposed between said first and second connection walls.

[0065] Preferably, said insulating material is disposed around said semiconductor module.

[0066] Preferably, said power module comprises a thermostat unit.

[0067] Preferably, said thermostat unit is configured to regulate a temperature of said heat transfer fluid.

[0068] Brief description of the drawings

[0069] Further features and advantages will become apparent in light of the following detailed description of some preferred embodiments of the invention.

[0070] Such description is provided herein with reference to the annexed drawings, which are also supplied by way of non-limiting example, wherein: - Figure 1 shows a block diagram of a semiconductor module according to the present invention;

[0071] - Figure 2 shows an alternative block diagram of a semiconductor module according to the present invention;

[0072] - Figure 3 is an illustrative circuit diagram of the semiconductor module of Figure 1;

[0073] - Figure 4 is a diagram showing a detail of the semiconductor module of Figure 2; - Figure 5a shows a connection plate according to the present invention; - Figure 5b is a sectional view of the connection plate of Figure 5;

[0074] - Figure 6 shows a block diagram of the semiconductor module of Figure 1 connected to two connection plates;

[0075] - Figure 7 shows a perspective view of a power module according to different embodiments of the present invention;

[0076] - Figure 8 is a side view of the power module of Figure 7;

[0077] - Figure 9 is another view of the power module of Figure 7;

[0078] - Figure 10 is a front view of the power module of Figure 7;

[0079] - Figure 11 shows an illustrative circuit diagram of the power module of Figure 7;

[0080] - Figure 12 shows a coupling element according to the present invention;

[0081] - Figure 13 shows a sectional view of the coupling element of Figure 12; - Figure 14 shows a power converter in H-bridge configuration according to one embodiment of the present invention;

[0082] - Figure 15 shows an illustrative diagram of the converter of Figure 14; - Figure 16 shows an illustrative circuit diagram of the converter of Figure 14;

[0083] - Figure 17 shows a block diagram of a power converter in three-phase inverter configuration according to a further embodiment of the present invention;

[0084] - Figure 18 shows an illustrative circuit diagram of the converter of Figure 17;

[0085] - Figures 19a-19b and 20 are schematic plan views of the semiconductor module of Figures 1-2, with some parts removed in order to highlight other parts;

[0086] - Figure 21 schematically shows the general structure of a power module in accordance with the present invention.

[0087] The drawings show different aspects and embodiments of the present invention and, wherever appropriate, similar structures, components, materials and / or elements are designated in the various drawings by the same reference numerals. The drawings are not necessarily in scale, nor are the various elements necessarily represented with correct proportions.

[0088] Detailed description of some embodiments

[0089] With reference to Figure 1 and 2, reference numeral 10 designates a semiconductor module.

[0090] The semiconductor module 10 comprises at least one semiconductor device 11. The semiconductor device 11 is a controlled electric switching element. Preferably, the semiconductor device 11 comprises a transistor. For example, the semiconductor device 11 comprises an IGBT (Insulated-Gate Bipolar Transistor).

[0091] Preferably, the semiconductor device 11 is made of silicon. Preferably, the semiconductor device 11 is made of silicon carbide (SiC) or gallium arsenide (GaN).

[0092] Preferably, the semiconductor device 11 has a thickness ranging between 100 and 400 pm; a length ranging between 1 and 5 mm; a width ranging between 1 and 5 mm.

[0093] The semiconductor module 10 further comprises:

[0094] - a first connection wall 12;

[0095] - a second connection wall 13.

[0096] The first connection wall 12 and the second connection wall 13 have a substantially planar conformation. In particular, the first connection wall 12 and the second connection wall 13 have a substantially parallelepiped shape; in each one of the first and second connection walls 12, 13, one of the two faces with the largest area faces towards, and is in contact with, the semiconductor device 11.

[0097] Preferably, the first connection wall 12 and the second connection wall 13 have a thickness ranging between 200 and 600 pm; a length ranging between 10 and 60 mm; a width ranging between 10 and 60 mm.

[0098] In general, the area of the semiconductor device 11 is, in a plan view, smaller than that of the first and second connection walls 12. Preferably, the semiconductor device 11 has, in a plan view, an area ranging between 0.025 % and 50 % of the area of each one of the first and second connection walls 12, 13. In this regard, reference can be made to Figures 19a-19b, which show respective plan views schematically representing, by way of example, the relation between the area of the semiconductor device 11 and the area of the first and second walls 12, 13.

[0099] Preferably, the first connection wall 12 and the second connection wall 13 are made of metal. For example, the first connection wall 12 and the second connection wall 13 are made of aluminium and / or copper.

[0100] As schematically shown in Figures 1-2, the first connection wall 12 is in contact with a first face 11a of the semiconductor device 11. The second connection wall 13 is in contact with a second face lib of the semiconductor device 11.

[0101] The first face 11a and the second face lib of the semiconductor device 11 are opposite to each other.

[0102] Preferably, the first and second faces 11a, lib of the semiconductor device 11 are the largest surfaces of the semiconductor device 11.

[0103] The first connection wall 12 and the second connection wall 13 are electrically connected to the semiconductor device 11 and exchange heat with the semiconductor device 11.

[0104] For example, the first face 11a of the semiconductor device 11 is fixed, e.g. by soldering, to the first connection wall 12.

[0105] For example, the second face 11 b of the semiconductor device 11 is fixed, e.g. by soldering, to the second connection wall 13.

[0106] Preferably, the semiconductor module 10 comprises an electrically insulating material 16. The insulating material 16 is interposed between the first and second connection walls 12, 13. In particular, the insulating material 16 occupies the space between the first and second connection walls 12, 13 not occupied by the semiconductor device 11. For example, the insulating material 16 is disposed around the semiconductor device 11, as schematically shown in Figures 1-2 and 20.

[0107] Preferably, the insulating material 16 is a ceramic material. Preferably, the insulating material 16 may be mica or silicon carbide or alumina. In addition or as an alternative, the insulating material 16 may be a resin, e.g. of the same type as the one currently in use for transistor cases. In general, the insulating material 16 has the following main characteristics: high dielectric strength, and coefficients of thermal expansion similar to those of silicon and copper.

[0108] Note that the insulating material 16 and the first and second connection walls 12, 13 form a snubber capacitor CSnb. Said capacitor CSnb can be properly sized by adjusting the thickness of the insulating material 16 and the thickness of the first and second connection walls 12, 13, as shown in Figures 1-2.

[0109] Figure 3 shows a diagram of the semiconductor module 10, wherein the semiconductor device 11 comprises:

[0110] • a switch; and

[0111] • a flyback diode connected in parallel with said switch.

[0112] Alternatively, in accordance with the present invention, the semiconductor device 11 may comprise, for example, an insulated-gate bipolar transistor, a MOSFET, or anyway a generic transistor.

[0113] The semiconductor module 10 comprises a control terminal G. The control terminal G extends outside the semiconductor device 11 and is connected to the gate / base of the semiconductor device 11.

[0114] Preferably, the first connection wall 12 is connected to the emitter / source of the semiconductor device 11, and the second connection wall 13 is connected to the collector / drain of the semiconductor device 11.

[0115] With reference to the exemplary embodiment shown in Figure 3 - wherein the semiconductor device 11 comprises a switch - the first connection wall 12 corresponds to the source S of the semiconductor device 11; the second connection wall 13 corresponds to the drain D of the semiconductor device 11; the control terminal G of the semiconductor module 10 corresponds to the gate of the semiconductor device 11.

[0116] Preferably, as schematically shown in Figure 4, the source S of the semiconductor device 11 is connected to a connection terminal 18 extending out of the semiconductor module 10.

[0117] In accordance with the present invention, a power module 100 (Figure 7-11) is provided.

[0118] The power module 100 comprises:

[0119] - a number N of semiconductor modules 10.1-10. n, each one substantially equal to the above-described semiconductor module 10; and

[0120] - a number M of connection plates 20.1-20. m.

[0121] Number N is greater than or equal to one. Therefore, one or more semiconductor modules 10.1-10. n can be employed.

[0122] Number M is equal to N + l. Therefore, two or more connection plates 20. 1-20. m can be employed.

[0123] Each semiconductor module 10. k (belonging to the N semiconductor modules 10.1-10. n) is interposed between a respective pair of connection plates including a first connection plate 2O.j and a second connection plate 2O.j + l arranged on opposite sides of said semiconductor module (Figure 6).

[0124] The first connection plate 2O.j and the second connection plate 2O.j + l belong to the number M of connection plates 20.1-20. m.

[0125] Each semiconductor module 10. k is in contact with the respective pair of connection plates 2O.j, 2O.j + l, so that:

[0126] - on one side, the semiconductor module 10. k is in galvanic contact with the first connection plate 2O.j and exchanges heat with the first connection plate 2O.j, and

[0127] - on the other side, the semiconductor module 10. k is in galvanic contact with the second connection plate 2O.j + l and exchanges heat with said second connection plate 2O.j + l.

[0128] More particularly, the first connection plate 2O.j is in contact with the first connection wall 12, and the second connection plate 2O.j + l is in contact with the second connection wall 13.

[0129] Figures 5a-5b schematically show a connection plate 20, which is an example representing each one of the M connection plates 20.1-20. m. The connection plate 20 comprises a box-shaped body 25. Preferably, the box-shaped body (e.g. having a substantially parallelepiped shape) 25 has a top surface 26 and a bottom surface 27, both of which are substantially flat. Preferably, the area of the top surface 26 and bottom surface 27 of the box-shaped body 25 is greater than or equal to the area of the surface of the first connection wall 12 and / or of the second connection wall 13 in contact with the top surface 26 I bottom surface 27.

[0130] For example, the box-shaped body of the connection plate 20 has a width ranging between 20 and 100 mm; a length ranging between 20 and 100 mm, and a thickness ranging between 3 and 20 mm.

[0131] Preferably, the box-shaped body 25 is made of metal. Preferably, the box-shaped body 25 is made of aluminium and / or copper and / or gold and / or silver.

[0132] Preferably, the connection plate 20 comprises a connector 21. The connector 21 preferably has an elongate conformation (e.g. a rod-like shape) extending outwards from one side of the box-shaped body 25. Alternatively, the connector 21 has a lamellar conformation (not shown) extending outwards from one side of the box-shaped body 25.

[0133] Preferably, the connector 21 extends outwards from one side of the boxshaped body 25 for a length of 20 to 50 mm.

[0134] Preferably, the connection plate 20 comprises a primary duct 22. In particular, the primary duct 22 is formed within the box-shaped body 25. Preferably, the primary duct 22 has an inside diameter ranging between 2.5 and 19.5 mm. Optionally, the primary duct 22 is coated with an electrically insulating material.

[0135] Preferably, the connection plate 20 comprises a secondary duct 23. In particular, the secondary duct 23 is formed within the box-shaped body 25. Preferably, the secondary duct 23 has an inside diameter ranging between 2.5 and 19.5 mm. Optionally, the secondary duct 23 is coated with an electrically insulating material.

[0136] The primary duct 22 has an inlet mouth 22' and an outlet mouth 22". Likewise, the secondary duct 23 has an inlet mouth 23' and an outlet mouth 23".

[0137] Preferably, as shown in Figure 5b, the inlet mouth 22' and the outlet mouth 22" of the primary duct 22 are located on a first side A of the boxshaped body 25 of the connection plate 20.

[0138] Preferably, the inlet mouth 23' and the outlet mouth 23" of the secondary duct 23 are located on the first side A of the box-shaped body 25 of the connection plate 20.

[0139] Preferably, the inlet mouths 22' and 23' and the outlet mouths 22" and 23" are separated by a central axis X-X of the first connection plate 20. Even more preferably, the inlet mouths 22' and 23' and the outlet mouths 22" and 23" are separate from each other and disposed symmetrically relative to the central axis X-X. Preferably, the primary duct 22 is formed in an inner region of the box-shaped body 25; the secondary duct 23 is formed in a peripheral region of the box-shaped body 25.

[0140] Preferably, the primary duct 22 and the secondary duct 23 are disposed within the box-shaped body 25 at a mutual distance of 0.25 to 2.5 mm. Optionally, the connector 21 extends from the first side A of the boxshaped body 25. Preferably, the connector 21 extends, at least partly, along the central axis X-X of the connection plate 20. Note that the primary duct 22 and the secondary duct 23 are shown, for simplicity, as having a substantially U-shaped development; in practice, however, it is possible (and preferable) to use different conformations aimed at ensuring - as will become apparent below - a better heat exchange with the adjacent semiconductor module (or with the adjacent semiconductor modules).

[0141] Preferably, the primary and secondary ducts 22, 23 have a direction of development that is substantially parallel to the top and bottom surfaces 26, 27.

[0142] Referring back to Figure 6, which schematically shows a generic semiconductor module 10. k (belonging to the N semiconductor modules 10. 1-10. n) interposed between a first and a second connection plate 2O.j, 2O.j + l (belonging to the M connection plates 20.1-20. m), it can be observed that, preferably, the primary duct 22a, 22b of each connection plate 2O.j, 2O.j + l develops - within the respective box-shaped body 25a, 25b - under / above the semiconductor device 11 of the semiconductor module 10. k.

[0143] Preferably, the secondary duct 23a, 23b develops in a peripheral region of the respective box-shaped body 25a, 25b.

[0144] In other words, the primary duct 22a, 22b of each connection plate 2O.j, 2O.j + l develops in the hottest region of the semiconductor module 10. k. Note that there is no electrically insulating material between the first connection plate 2O.j and the semiconductor module 10. k connected thereto. Likewise, there is no electrically insulating material between the second connection plate 2O.j + l and the semiconductor module 10. k.

[0145] In other words, the first connection plate 2O.j and the second connection plate 2O.j + l are neither thermally nor electrically insulated from the semiconductor module 10. k.

[0146] Note that each connection plate 2O.j, 2O.j + l (as well as all other connection plates of the M connection plates 20.1-20. m) performs a dual function:

[0147] - allowing the semiconductor module 10 to be electrically connected to a source of electric energy or, more generally, to other electric components / devices;

[0148] - allowing the semiconductor module 10. k to be temperature-regulated by exploiting the heat transfer fluid flowing in the respective primary duct 22a, 22b and / or in the respective secondary duct 23a, 23b.

[0149] Preferably, the control terminal G of the semiconductor module 10 extends outwards on a side B of the power module 100.

[0150] Preferably, the side B of the power module 100 is opposite to the side A of the box-shaped body 25 of the first connection plate 20.

[0151] In other words, the control terminal G of the semiconductor module 10 extends outwards from the power module 100 from a surface opposite to the surface from which the connector 21 of the first connection plate 20 extends.

[0152] As aforesaid, the first connection plate 2O.j is in contact with the first connection wall 12 of the semiconductor module 10. k, and the second connection plate 2O.j + l is in contact with the second connection wall 13 of the semiconductor module 10. k.

[0153] The expression "in contact with" refers to electric and thermal contact between two surfaces (i.e. current can flow and heat can be transferred through such two surfaces). For example, contact between such two surfaces can be obtained by mechanical contact, soldering, inductive glue, or the like.

[0154] In one implementation example, contact between the first and second connection walls 12, 13 and the first and second connection plates 2O.j, 2O.j + l can be obtained by means of elastic metal fins disposed on the first and second connection walls 12, 13 and / or on the first and second connection plates 2O.j, 2O.j + l, which are deformed (preferably by compression) when the semiconductor module 10. k is inserted between the first and second connection plates 20. lj 2O.j + l, e.g. in a direction substantially parallel to the planar development of the semiconductor module 10. k. In this case, the first and second connection plates 2O.j, 2O.j + l are preferably secured to a lateral structure, which holds them in position, thus permitting the insertion of the semiconductor module 10. k. Due to their elasticity, the fins exert a mechanical action on the semiconductor module 10. k, thereby holding it in position after it has been inserted. Such fins provide the electric and thermal connection between the first and second connection walls 12, 13 and the first and second connection plates 2O.j, 2O.j + l. In one embodiment, said lateral structure may consist of, or be fixed to, the hydraulic connector 120 (which will be described later on).

[0155] The semiconductor module 10. k is thus interposed between the bottom surface of the box-shaped body 25 of the first connection plate 2O.j and the top surface of the box-shaped body 25 of the second connection plate 2O.j + l. Each one of the N semiconductor modules 10.1-10. n is in this configuration, i.e. interposed between two connection plates.

[0156] In this manner, the semiconductor modules 10.1-10. n and the connection plates 20.1-20. m form a sandwich or stack structure.

[0157] Except for the two connection plates at the ends of the stack, which are in contact with one semiconductor module only, all other connection plates are interposed between two semiconductor modules.

[0158] The connection plates 20.1-20. m are in fluidic communication through a hydraulic connector 120, which will be further described later on.

[0159] With reference to Figure 6, the first connection plate 2O.j is electrically connected to the source S of the semiconductor module 11 through the first connection wall 12. The second connection plate 2O.j + l is connected to the drain D of the semiconductor module 11 through the second connection wall 13.

[0160] Note that the terms "source" and "drain" are appropriate for a MOSFET configuration; in the case of an IGBT configuration, the same terminals should be referred to as "emitter" and "collector", respectively.

[0161] Note that, when a potential difference is applied across the connector 21b of the second connection plate 2O.j + l and the connector 21a of the first connection plate 2O.j, a potential difference will be applied across the drain D and the source S of the semiconductor device 11.

[0162] By appropriately driving the control terminal G of the semiconductor device 11, it is possible to allow / prevent a current flow across the connector 21b of the second connection plate 2O.j + l and the connector 21a of the first connection plate 2O.j.

[0163] As mentioned above, each one of the first and second connection plates 2O.j, 2O.j + l comprises a respective primary duct 22a, 22b and a respective secondary duct 23a, 23b.

[0164] In particular, each primary duct 22a, 22b permits a flow of a heat transfer fluid within the respective box-shaped body 25a, 25b.

[0165] Preferably, the heat transfer fluid is an electrically non-conductive fluid. In a different embodiment, the heat transfer fluid may be electrically conductive. In this case, as aforementioned, the primary duct and secondary duct 22, 23 of each connection plate 20.1-20. m are preferably coated with electrically insulating material.

[0166] In order to promote a flow of heat transfer fluid in the connection plates 20. 1-20. m, the power module 100 is equipped with a hydraulic device 130. The hydraulic device 130 may comprise, for example, a pump or similar equipment acting upon the heat transfer fluid to cause it to flow along the path defined by the primary ducts 22 and secondary ducts 23. At the end of said path, the heat transfer fluid returns to the hydraulic device 130 to receive a new fluid-dynamic thrust and keep flowing.

[0167] In practical terms, the hydraulic device 130, the primary ducts 22, the secondary ducts 23 and the hydraulic connector 120 form a closed path in which the heat transfer fluid flows. Advantageously, the power module 100 may comprise a thermostat unit, e.g. in the form of a heat exchanger.

[0168] The thermostat unit 140 is configured to exchange heat with the heat transfer fluid so as to regulate its temperature.

[0169] The thermostat unit 140 may be integrated into the hydraulic device 130, or mechanically associated with the hydraulic device 130 (e.g. forming, together with the hydraulic device 130, a single apparatus), or independent of and separate from the hydraulic device 130.

[0170] Preferably, in at least M-l connection plates the fluid flows in the primary duct 22 and, before flowing in the secondary duct 23, flows through at least another one of the M connection plates 20.1-20. m. More particularly, in just one connection plate not belonging to the M-l connection plates, the fluid exiting the primary duct 22 enters the secondary duct 23 without first flowing through any other connection plate.

[0171] Furthermore, the M connection plates 20. 1-20. m comprise a main connection plate having an inlet IN and an outlet OUT.

[0172] Through the inlet IN, the main connection plate receives the heat transfer fluid from the hydraulic device 130; through the outlet OUT, the heat transfer fluid returns to the hydraulic device 130 after having flowed through all the other connection plates via the hydraulic connector 120.

[0173] Preferably, the inlet IN is defined by an inlet mouth 22' of the primary duct 22 of the main connection plate.

[0174] Preferably, the outlet OUT is defined by an outlet mouth 23" of the secondary duct 23 of the main connection plate.

[0175] In one embodiment, the inlet IN and the outlet OUT are located on the same face of the main connection plate, as schematically shown in Figures 10 and 21.

[0176] Preferably, the flow of heat transfer fluid is guided in such a way that the heat transfer fluid can circulate through all connection plates 20.1-20. m, so as to perform - as will be further described below - a suitable temperature control function.

[0177] The M connection plates 20a-20m are preferably arranged in succession, from an initial connection plate 20.1 to a final connection plate 20. m. The connection plates 20.1-20. m are positioned in succession along an axis of development Y which is substantially orthogonal to the prevalently planar development of the connection plates 20.1-20. m themselves (Figure 21). The initial connection plate 20.1 and the final connection plate 20. m are located at the ends of said stack structure.

[0178] The heat transfer fluid enters the initial connection plate 20.1, flows through all connection plates in succession up to the final connection plate 20. m, and then flows again through all connection plates from the final connection plate 20. m to the initial connection plate 20.1.

[0179] Advantageously, the initial connection plate 20.1 is said main connection plate; in other words, the connection plate directly connected to the hydraulic device 130 is one of the two terminal connection plates of the succession of connection plates 20.1-20. m. More particularly, assuming that the stack is disposed vertically (e.g. with the connection plates disposed horizontally and with the axis of development Y of the stack disposed vertically, as schematically shown in Figure 21), the main connection plate is, preferably, the one in the lowest position, i.e. the one under which there are no other connection plates or semiconductor modules.

[0180] In order to allow the heat transfer fluid to flow through the various connection plates 20.1-20. m, the power module 100 is equipped with a hydraulic connector 120.

[0181] In particular, the hydraulic connector 120 is so designed as to guide the heat transfer fluid in accordance with the above-indicated sequence of connection plates.

[0182] For example, the hydraulic connector 120 can connect the primary duct 22 and the secondary duct 23 of each connection plate 20.1-20. m in such a way that the heat transfer fluid will flow through, in series, each primary duct 22 first and then, in series, each secondary duct 23.

[0183] For example, as shown in Figure 10, the hydraulic connector 120 may comprise five junction ducts 121a-121e:

[0184] • the first junction duct 121a puts the outlet mouth 22a" of the primary duct 22a of the first connection plate 2O.j in fluidic communication with the inlet mouth 22b' of the primary duct 22b of the second connection plate 2O.j + l;

[0185] • the second junction duct 121b puts the outlet mouth 22b" of the primary duct 22b of the second connection plate 2O.j + l in fluidic communication with the inlet mouth 22c' of the primary duct 22c of the third connection plate 2O.j + 2;

[0186] • the third junction duct 121c puts the outlet mouth 22c" of the primary duct 20c of the third connection plate 2O.j + 2 in fluidic communication with the inlet mouth 23c' of the secondary duct 23c of the third connection plate 2O.j + 2;

[0187] • the fourth junction duct 121d puts the outlet mouth 23c" of the secondary duct 23c of the third connection plate 2O.j + 2 in fluidic communication with the inlet mouth 23b' of the secondary duct 23b of the second connection plate 2O.j + l;

[0188] • the fifth junction duct 121e puts the outlet mouth 23b" of the secondary duct 23b of the second connection plate 2O.j + l in fluidic communication with the inlet mouth 23a' of the secondary duct 23a of the first connection plate 2O.j.

[0189] Assuming that the power module 100 comprises no other connection plates than those shown in Figure 10, there will be a total of M = 3 connection plates. Thus, the first connection plate 2O.j will represent the initial connection plate 20.1, and the third connection plate 2O.j + 2 will represent the final connection plate 20. m.

[0190] In one embodiment, the hydraulic connector 120 comprises a single block having a substantially rectangular shape. Every junction duct 121a-121e is formed within said single block.

[0191] Preferably, the single block of the hydraulic connector 120 comprises a plurality of apertures. In particular, such apertures are so shaped as to permit the passage of a respective connector 21a-21m of a respective connection plate 20a-20m.

[0192] Preferably, the hydraulic connector 120 comprises a current sensor adapted to generate a signal which is proportional to the current flowing through the connector 21b of the second connection plate 20b. For example, the current sensor is a Hall-effect sensor. In particular, the current sensor is inserted in the aperture through which the connector 21b of the second connection plate 20b is made to pass (i.e. the connector corresponding to the phase terminal of the power module 100).

[0193] Preferably, the hydraulic connector 120 comprises a voltage sensor. In particular, the voltage sensor is positioned on the surface of the single block of the hydraulic connector 120. Preferably, the voltage sensor is so connected as to generate a signal which is proportional to the phase voltage of the power module 100.

[0194] Preferably, the hydraulic connector 120 comprises a temperature sensor. Preferably, the temperature sensor is adapted to supply a signal which is proportional to the temperature of the heat transfer fluid and / or of at least one connection plate 20a, 20b, ..., 20m.

[0195] Preferably, the hydraulic connector 120 is made of an electrically insulating material.

[0196] In one embodiment, the hydraulic connector 120 comprises one or more vertical ducts (i.e. ducts transversal, and preferably orthogonal, to the planar development of the connection plates 20.1-20. m and semiconductor modules 10.1-10. n), which put the connection plates 20.1-20. m in fluidic communication with each other. In particular, each one of such vertical ducts puts a connection plate in fluidic communication with an adjacent connection plate (i.e. the two connection plates are separated by a semiconductor module), crossing the semiconductor module interposed between the two connection plates. Preferably, the insulating material of said semiconductor module has one or more through holes that are transversal, in particular orthogonal, to the planar development of the semiconductor module itself; each one of such one or more through holes is crossed by a respective vertical duct. For example, a vertical duct can connect the primary or secondary duct of a connection plate with the primary or secondary duct of an adjacent connection plate. By suitably arranging various vertical ducts, it is possible to cause the heat transfer fluid to flow through the connection plates 20a-20m as desired. Through a hydraulic connector 120 including said vertical ducts, a compact power module can be obtained because no space is occupied by, for example, the junction ducts 121a-121e described above by way of example.

[0197] In general, the heat transfer fluid flowing in each primary and secondary duct 22, 23 of each connection plate 20.1-20. m makes it possible to control the temperature of each semiconductor module 10.1-10. n.

[0198] The temperature regulation provided by the thermostat unit 140 may occur while the power module 100 is in operation and / or during periods of inactivity of the power module 100.

[0199] The temperature regulation provided by the thermostat unit 140 can keep the temperature (e.g. the average temperature) of the power module 100 substantially constant, or at least within a predefined range.

[0200] Temperature control can be effected by having the heat transfer fluid release heat as it flows in the primary and secondary ducts 22, 23 comprised in all connection plates 20a-20m, or by having the heat transfer fluid absorb heat as it flows in one or more primary ducts 22 and / or in one or more secondary ducts 23.

[0201] The Applicant observes that the power module 100 may, when it comprises a plurality of semiconductor devices 10a, 10b, ..., lOn mutually connected in series, be used as a switch cascode.

[0202] The principle of operation of a switch cascode is per se known and will not therefore be described in detail.

[0203] By way of example, Figure 7 schematically shows a power module 100 comprising:

[0204] - two (N = 2) semiconductor modules 10. k, 10.k+l; and

[0205] - three (M = 3) connection plates 2O.j, 2O.j + l, 2O.j + 2.

[0206] In particular, the first semiconductor module 10. k is interposed between the first connection plate 2O.j and the second connection plate 2O.j + l. The second semiconductor module 10.k+l is interposed between the second connection plate 2O.j + l and the third connection plate 2O.j + 2.

[0207] Even more particularly, the bottom surface of the first connection wall 12 of the first semiconductor module 10. k is in contact with (e.g. welded / glued or fitted to) the top surface of the box-shaped body 25a of the first connection plate 2O.j; the top surface of the second connection wall 13 of the first semiconductor module 10. k is in contact (e.g. welded / glued or fitted to) the bottom surface of the box-shaped body 25b of the second connection plate 2O.j + l.

[0208] The bottom surface of the first connection wall 12 of the second semiconductor module lO.k+1 is in contact with (e.g. welded / glued or fitted to) the top surface of the box-shaped body 25b of the second connection plate 2O.j + l. The top surface of the second connection wall 13 of the second semiconductor module lO.j + 1 is in contact with (e.g. welded / glued or fitted to) the bottom surface of the box-shaped body 25c of the third connection plate 2O.j + 2.

[0209] Note that the second connection plate 2O.j + l is electrically and thermally connected to both the first semiconductor module 10. k and the second semiconductor module lO.k+1.

[0210] As schematically shown in Figures 7-11, the power module 100 preferably comprises a control board 110. Preferably, the control board 110 comprises at least one integrated circuit Illa, 111b adapted to drive (i.e. to electrically open / close) each semiconductor device 11. Preferably, the control board 110 comprises a respective integrated circuit Illa, 111b configured to drive the control terminal Ga, Gb of a respective semiconductor device 11a, lib.

[0211] For example, the control board 110 preferably comprises a first integrated circuit Illa. The first integrated circuit Illa is connected to and configured to drive the control terminal Ga of the first semiconductor device 11a. Preferably, the first integrated circuit Illa is connected to the control terminal Ga and to the source S of the first semiconductor device 11a. For example, the first integrated circuit Illa is connected to the connection terminal 18a and to the control terminal Ga of the first semiconductor device 11a. Preferably, the control board 110 comprises a second integrated circuit 110b. The second integrated circuit 110b is connected to and configured to drive the control terminal Gb of the second semiconductor device lib. Preferably, the second integrated circuit 111b is connected to the control terminal Gb and to the source S of the second semiconductor device lib. For example, the second integrated circuit 111b is connected to the connection terminal 18b and to the control terminal Gb of the second semiconductor device lib.

[0212] Preferably, the power module 100 comprises at least one DC-Link capacitor 41, 42, 43. Preferably, the at least one DC-Link capacitor 41, 42, 43 is connected to the initial connection plate 20.1 and to the final connection plate 20. m.

[0213] For example, with reference to Figures 7-11 (wherein it is assumed that the power module 100 comprises no other connection plates than those illustrated), the at least one DC-Link capacitor 41, 42, 43 is connected to the first connection plate 2O.j and to the third connection plate 2O.j + 2 (M = 3). For example, the at least one DC-Link capacitor 41, 42, 43 is connected to the box-shaped body 25a of the first connection plate 2O.j and to the box-shaped body 25c of the third connection plate 2O.j + 2 by means of a respective metal bridge 41', 42', 43' (Figure 9).

[0214] According to a further aspect, the present invention provides a power converter 200 comprising a plurality of power modules 100 as described above.

[0215] Preferably, the adjacent modules of said plurality of power modules 100 are mutually connected mechanically and / or electrically by means of at least one coupling element 50.

[0216] In particular, at least one connection plate 20a, 20b, ..., 20m of a respective power module 100 is mechanically and / or electrically connected to a respective connection plate 20a', 20b', ..., 20m' of an adjacent power module 100' by means of a respective coupling element 50.

[0217] Even more preferably, the adjacent modules of said plurality of power modules 100 are mutually connected mechanically and / or electrically by means of a number K of coupling elements 50.

[0218] Preferably, the number K of coupling elements 50a, ..., 50k is smaller than or equal to:

[0219] K=(M*(a-l));

[0220] where M is the number of connection plates of the power module 100, and a is the number of power modules 100.

[0221] As shown in Figures 12 and 13, each coupling element 50 preferably has a respective first coupling means 51 and a respective second coupling means 52. For example, the first coupling means 51 and the second coupling means 52 are positioned on opposite surfaces of the coupling element 50.

[0222] Preferably, each connection plate 20a, 20b, ..., 20m of a respective power module 100 is provided with at least one respective coupling seat 29a, 29b, ..., 29m (Figure 5a).

[0223] Each coupling seat 29 is adapted to engage, preferably in a releasable manner, a coupling element 50 through the first or second coupling means 51, 52. For example, each coupling seat 29 releasably engages the first or the second coupling means 51, 52 through a dovetail joint.

[0224] According to the present invention, the coupling elements 50 are made of either an electrically conductive material or an electrically insulating material.

[0225] In particular, coupling elements 50 made of electrically conductive material (e.g. copper and / or aluminium) allow connecting a connection plate 20a, 20b, ..., 20m of a power module 100 electrically and mechanically to a respective connection plate 20a', 20b', ..., 20m' of an adjacent power module 100'. Coupling elements 50 made of electrically insulating material (e.g. ceramic) allow connecting a connection plate 20a, 20b, ..., 20m of a power module 100 mechanically to a respective connection plate 20a', 20b', ..., 20m' of an adjacent power module 100'.

[0226] Preferably, a number i of coupling elements 50 are made of metallic material, e.g. copper and / or aluminium.

[0227] Preferably, a number (K-i) of coupling elements 50 are made of insulating material, e.g. ceramic.

[0228] In particular, the insulating material is preferably a material having a coefficient of thermal expansion which is similar to the coefficient of thermal expansion of the metallic material.

[0229] Note that, by means of the number K of coupling elements 50, it is possible to mechanically and / or electrically connect a plurality of power modules 100 to each other in order to obtain power converters 200 in different configurations.

[0230] For example, by appropriately selecting the coupling elements 50 (i.e. by choosing whether to use an electrically conductive coupling element 50 or an electrically insulating one), it is possible to connect a plurality of power modules 100 to each other to obtain power converters 200 configured as: an H-bridge; a stack of H-bridges; a three-phase inverter, a cascode of Flbridges, etc. By way of example, the following will describe some configurations of power converters 200 according to some embodiments of the present invention.

[0231] With reference to Figures 14, 15 and 16, an embodiment of the power converter 200 will now be described wherein said power converter 200 has an H-bridge configuration.

[0232] In particular, as shown in Figures 14 and 15, the power converter 200 comprises:

[0233] • two (a=2) power modules 100, 100', wherein each power module 100, 100' comprises, respectively, two (N = 2, N'=2) semiconductor devices 10a, 10b, 10a', 10b' and three (M = 3, M'=3) connection plates 20a, 20b, 20c, 20a', 20b', 20c';

[0234] • and three (K=M = 3) coupling elements 50.

[0235] In the following, with reference to Figure 15, the three coupling elements will be indicated as: upper coupling element 50a; lower coupling element 50m; and intermediate coupling element 50i.

[0236] According to this embodiment, the upper coupling element 50a and the lower coupling element 50m are made of electrically conductive material (i=2); the intermediate coupling element 50i is made of electrically insulating material.

[0237] The first power module 100 and the second power module 100' are connected in H-bridge configuration as follows:

[0238] • the first connection plate 20a of the first power module 100 is electrically connected to the first connection plate 20a' of the second power module 100';

[0239] • the second connection plate 20b of the first power module 100 is not electrically connected to the second connection plate 20b' of the second power module 100';

[0240] • the third connection plate 20c of the first power module 100 is electrically connected to the third connection plate 20c' of the second power module 100';

[0241] More specifically, the first power module 100 and the second power module 100' are connected in H-bridge configuration as follows:

[0242] • the upper coupling element 50a connects the first connection plate 20a of the first power module 100 mechanically and electrically to the first connection plate 20a' of the second power module 100';

[0243] • the intermediate coupling element 50i connects the intermediate connection plate 20b (i.e. the second connection plate 20b) of the first power module 100 mechanically, but not electrically, to the intermediate connection plate 20b' (i.e. the second connection plate 20b') of the second power module 100';

[0244] • the lower coupling element 50m connects the last connection plate 20c (i.e. the third connection plate 20c) of the first power module 100 mechanically and electrically to the last connection plate 20c' (i.e. the third connection plate 20c') of the second power module 100'.

[0245] As described above, the first power module 100 and the second power module 100' comprise a respective control board 110 adapted to drive each semiconductor device 10a, 10b, 10a', 10b'.

[0246] Preferably, the at least one DC-Link capacitor 41, 41' is connected across the first connection plate 20a, 20a' and the last connection plate 20c, 20c' of the first and / or second power module 100, 100'.

[0247] Preferably, as shown in Figure 16, the first power module 100 and the second power module 100' are driven by a single control board 110.

[0248] Said control board comprises a plurality of integrated circuits Illa, lib, Illa', 111b' adapted to drive, respectively, a semiconductor device 10a, 10b, 10a', 10b'. For example:

[0249] • the first integrated circuit Illa is connected to and configured to drive the control terminal Ga of the first semiconductor device 10a of the first power module 100;

[0250] • the second integrated circuit 111b is connected to and configured to drive the control terminal Gb of the second semiconductor device 10b of the first power module 100;

[0251] • the third integrated circuit Illa' is connected to and configured to drive the control terminal Ga' of the first semiconductor device 10a' of the second power module 100';

[0252] • the fourth integrated circuit 111b' is connected to and configured to drive the control terminal Gb' of the second semiconductor device 10b' of the second power module 100'.

[0253] Note that, for example, by applying a potential difference across the connector 21a of the first connection plate 20a of the first module 100 and the connector 21c of the third connection plate 20c' of the first power module 100, and by appropriately driving each semiconductor device 10a, 10b, 10a', 10b', it is possible to use the power converter 200 as an H-bridge converter in which the connector 21b of the second connection plate 20b of the first power module 100 and the connector 21b' of the second connection plate 20b' of the second power module 100' are the phase terminals.

[0254] The principle of operation of an H-bridge power converter is known and will not therefore be described in detail.

[0255] The Applicant observes that the power module 100 shown in Figure 11 is substantially similar to an inverter leg.

[0256] In particular, the first semiconductor device 10a is connected in series -by means of the second connection plate 20b - to the second semiconductor device 10b. The connector 21a of the first connection plate 20a corresponds to the positive terminal of the inverter leg; the connector 21b of the second connection plate 20b corresponds to the phase terminal (P) of the inverter leg; the connector 21c of the third connection plate 21c corresponds to the negative terminal (-) of the inverter leg.

[0257] The Applicant observes that, by adding a third power module to the power converter 200 of Figure 15, it is possible to obtain a power converter 200 that can be configured as a three-phase inverter. In particular, according to this embodiment, shown in Figures 17 e 18, the power converter 200 comprises: three (a=3) power modules 100, 100', 100", and six (K = 6) coupling elements 50. Each power module 100, 100', 100" comprising, respectively, two (N = 2, N'=2) semiconductor devices 10a, 10b, 10a', 10b', 10a", 10b", and three (M = 3, M'=3) connection plates 20a, 20i, 20m, 20a', 20i', 20m', 20a', 20i', 20m'.

[0258] Such six coupling elements comprise:

[0259] • a first and a second upper coupling element 50a, 50a' and a first and a second lower coupling elements 50m, 50m' made of electrically conductive material; and

[0260] • a first and a second intermediate coupling element 50i, 50i' made of electrically insulating material.

[0261] In particular, as shown in Figure 17, the first power module 100, the second power module 100' and the second power module 100" are connected by means of such coupling elements 50a, 50a', 50i, 50i', 50m, 50m' as follows:

[0262] • the first upper coupling element 50a connects the first connection plate 20a of the first power module 100 mechanically and electrically to the first connection plate 20a' of the second power module 100';

[0263] • the first intermediate coupling element 50i connects the intermediate connection plate 20b (i.e. the second connection plate 20b) of the first power module 100 mechanically, but not electrically, to the intermediate connection plate 20b' (i.e. the second connection plate 20b') of the second power module 100';

[0264] • the first lower coupling element 50m connects the last connection plate 20c (i.e. the third connection plate 20c) of the first power module 100 mechanically and electrically to the last connection plate 20c' (i.e. the third connection plate 20c') of the second power module 100';

[0265] • the second upper coupling element 50a' connects the first connection plate 20a' of the second power module 100' mechanically and electrically to the first connection plate 20a" of the third power module 100";

[0266] • the second intermediate coupling element 50i' connects the intermediate connection plate 20b' (i.e. the second connection plate 20b') of the second power module 100' mechanically, but not electrically, to the intermediate connection plate 20b" (i.e. the second connection plate 20b") of the third power module 100";

[0267] • the second lower coupling element 50m' connects the last connection plate 20c' (i.e. the third connection plate 20c') of the second power module 100' mechanically and electrically to the last connection plate 20c" (i.e. the third connection plate 20c") of the third power module 100".

[0268] As described above, the first power module 100, the second power module 100' and the third power module 100" comprise a respective control board 110 adapted to drive each semiconductor device 10a, 10b, 10a', 10b', 10a", 10b" (Figure 18).

[0269] Note that, for example, by applying a potential difference across the connector 21a of the first connection plate 20a of the first module 100 and the connector 21c of the third connection plate 20c' of the first power module 100, and by appropriately driving each semiconductor device 10a, 10b, 10a', 10b', 10a", 10b", it is possible to use the power converter 200 as a three-phase inverter in which the connector 21b of the second connection plate 20b of the first power module 100 substantially corresponds to a first phase terminal; the connector 21b' of the second connection plate 20b' of the second power module 100' substantially corresponds to a first phase terminal; and the connector 21b" of the second connection plate 20b" of the third power module 100" substantially corresponds to a third phase terminal.

[0270] The principle of operation of a three-phase inverter is per se known and will not therefore be described in detail. As described above, each power module 100, 100', 100" preferably comprises a respective hydraulic connector 120.

[0271] Preferably, the hydraulic connectors 120 of each power module 100, 100', 100" are mutually connected in such a way as to permit circulation of the cooling fluid within each connection plate of a respective power module 100, 100', 100".

[0272] Preferably, the hydraulic connectors 120 of each power module 100, 100', 100" connect the primary duct and the secondary duct of each connection plate 20a, 20b, 20c, 20a', 20b', 20c', 20a", 20b", 20c" in such a way that the cooling fluid will flow through, in succession, each primary duct first, and then each secondary duct, thus obtaining a respective cooling duct 120' having a respective inlet mouth IN and a respective outlet mouth OUT.

[0273] The cooling ducts 120' of each power module 100, 100', 100" are preferably connected to each other to form a cooling circuit of the power converter 200.

[0274] Preferably, the cooling ducts 120' of each power module 100, 100', 100" are connected in series or in parallel, or in a hybrid configuration, with each other. For example, when the cooling ducts 120' are connected in parallel, the inlet mouth IN of each cooling duct 120' is connected to a common manifold; and the outlet mouth OUT of each cooling duct 120' is connected to another common manifold (not shown).

[0275] The present invention offers some important advantages. In particular: - since there are no insulating elements between the semiconductor device 10 and the connection plates 20, parasitic capacitance is advantageously reduced;

[0276] - advantageously, the power density of the power module 100 is higher than that of prior-art power modules;

[0277] - advantageously, the connection plate 20 makes it possible to electrically connect the power module 100 and also to dissipate the heat generated by the power module 100 in operation.

[0278] Furthermore, the power module 100 according to the present invention advantageously permits the creation of a compact power converter 200.

[0279] Lastly, the power converter 200 according to the present invention is advantageously modular, i.e. it allows connecting and disconnecting power modules 100 to change the configuration of the power converter 200 as necessary.

[0280]

Claims

CLAIMS1. Power module comprising:a number N of semiconductor modules (10.1-10. n);a number M of connection plates (20.1-20. m);wherein N> = 1wherein M> = N + 1wherein each semiconductor module (10. k) is interposed between a respective pair of connection plates (20.1-20. m) including a first connection plate (2O.j) and a second connection plate (2O.j + l) arranged on opposite sides of said semiconductor module (10. k);wherein each semiconductor module (10. k) is in contact with the respective pair of connection plates, so that the semiconductor module (10. k) is in galvanic contact with the first connection plate (2O.j) on one side and exchanges heat with said first connection plate (2O.j), and is in galvanic contact with the second connection plate (2O.j + l) on the other side and exchanges heat with said second connection plate (2O.j + l); wherein each semiconductor module (10.1-10. n) comprises:a first and a second connection wall (12, 13) made of electrically and thermally conductive material;a semiconductor device (11), interposed between said first and second connection walls, and constituting a controlled switching element, said semiconductor device (11) having a first face (11a) in contact with the first connection wall (12) and a second face (lib) in contact with the second connection wall (13);wherein each connection plate (20.1-20. m) comprises:a box-shaped body (25) having at least one given face in contact with either the first or the second connection wall (12, 13) of one of said N semiconductor modules (10.1-10. n);wherein said box-shaped body (25) comprises at least one primary duct (22) and one secondary duct (23);wherein said primary duct (22) and said secondary duct (23) extend prevalently parallel to said given face;wherein said power module (100) further comprises a hydraulic device (130) in fluidic communication with the primary and secondary ducts (22, 23) of each one of said connection plates (20.1-20. m), and configured to promote a flow of a heat transfer fluid in the primary duct (22) and in the secondary duct (23) of each one of said connection plates (20.1-20. m), a hydraulic connector (120) that connects said connection plates (20.1-20. m) to each other,wherein said hydraulic connector (120) is functionally coupled to said hydraulic device (130) so that, in at least one of said M connection plates, the fluid flows in the primary duct (22) and, before flowing in the secondary duct (23), flows through at least another one of said M connection plates (20. 1-20. m).

2. Power module according to claim 1, wherein, in at least M-l connection plates, the fluid flows in the primary duct (22) and, before flowing in the secondary duct (23), flows through at least another one of said M connection plates (20.1-20. m).

3. Power module according to claim 2, wherein, in each one of said M-l connection plates, the primary duct (22) has an inlet mouth (22'), through which the heat transfer fluid enters, and an outlet mouth (22"), through which the heat transfer fluid exits to flow into another connection plate (20. 1-20. m),wherein, in each one of said M-l connection plates, the secondary duct (23) has an inlet mouth (23'), through which the heat transfer fluid coming from another connection plate enters, and an outlet mouth (23"), through which the heat transfer fluid exits.

4. Power module according to claim 2 or 3, wherein, in a connection plate not belonging to said M-l connection plates, the fluid exiting the primary duct (22) enters the secondary duct (23) without flowing through any other connection plate.

5. Power module according to any one of the preceding claims, wherein said M connection plates (20.1-20. m) comprise a main connection plate having an inlet (IN), which receives the heat transfer fluid from said hydraulic device (130), and an outlet (OUT), through which said heat transfer fluid returns to said hydraulic device (130) after having flowed through all the other connection plates via said hydraulic connector (120).

6. Power module according to claim 5, wherein, in said main connection plate, said inlet (IN) is defined by an inlet mouth (22') of the primary duct (22) of said main connection plate, and said outlet (OUT) is defined by an outlet mouth (23") of the secondary duct (23) of said main connection plate.

7. Power module according to claim 5 or 6, wherein said inlet (IN) and said outlet (OUT) are located on one same face of said main connection plate.

8. Power module according to any one of the preceding claims, wherein said M connection plates (20.1-20. m) are arranged in succession from an initial connection plate (20.1) to a final connection plate (20. m), wherein said heat transfer fluid enters the initial connection plate (20.1), flows through all connection plates in succession up to the final connection plate (20. m), and then flows again through all connection plates from the final connection plate (20. m) to the initial connection plate (20.1).

9. Power module according to claims 7 and 8, wherein the initial connection plate (20.1) is the main connection plate.

10. Power module according to claim 8 or 9, wherein said heat transfer fluid coming from said hydraulic device (130) first flows through the primary ducts (22) of all M connection plates (20.1-20. m), then flows through the secondary ducts (23) of all M connection plates (20.1-20. m), and then returns to said hydraulic device (130).

11. Power module according to any one of the preceding claims, wherein said semiconductor device (11) has, in a plan view, an area which is smaller than that of said first and second connection walls (12, 13).

12. Power module according to claim 11, wherein each semiconductor module (10.1-10. n) comprises an electrically insulating material (16) interposed between said first and second connection walls (12, 13), around said semiconductor device (11).

13. Power module according to any one of the preceding claims, comprising a thermostat unit (140) configured to regulate a temperature of said heat transfer fluid.

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