ELECTRICAL POWER MODULE

Description

[0001] The invention relates to the field of electrical power modules. BACKGROUND OF THE INVENTION

[0002] A power module typically includes semiconductors acting as switches. The semiconductors are mounted on an electrically insulating substrate.

[0003] The electrical power module includes, for example, an inverter intended to control an electric motor of an electromechanical actuator.

[0004] Semiconductors are, for example, power transistors such as JFET, IGBT or MOSFET.

[0005] The substrate, for example, consists of a ceramic layer which has a metallization layer on each of its faces. In addition to electrical insulation, the role of the substrate is to transfer the heat flow dissipated by the semiconductors.

[0006] Such an electric power module also typically includes a base plate that dissipates the heat flow and provides mechanical support for the electric power module. The base plate is generally made of copper or aluminum, and is usually mounted on a heat sink.

[0007] The operation of the electrical power module generates temperature cycles that can be relatively severe. The temperature cycles produce significant mechanical stresses in the substrate and at the interfaces between the substrate and the semiconductors. These mechanical and thermal stresses are the cause of multiple failure modes of the electrical power module, and tend to increase the probability of the occurrence of a failure in the electrical power module. Document US2016 / 105004A1 discloses an electrical power module comprising the characteristics of the preamble of claim 1. SUBJECT OF THE INVENTION

[0008] The object of the invention is to reduce the probability of a breakdown occurring in an electrical power module. SUMMARY OF THE INVENTION

[0009] In order to achieve this aim, an electrical power module is proposed comprising power components and supports each comprising at least one metal portion, the metal portions of the supports forming a substrate of the electrical power module, at least one support comprising two metal portions oriented relative to each other by an orientation angle greater than 0°, the two oriented metal portions being orthogonal to each other and a separate power component being fixed to each of said two oriented metal portions, each power component being fixed to two metal portions of two separate supports by being positioned between said two metal portions, the electrical power module being arranged so that electric power currents originating from or destined for the power components flow in the metal portions of the supports.

[0010] The supports of the electric power module, in which the electric power currents circulate, allow simultaneous tri-modal heat dissipation, by conduction, convection and radiation. This heat dissipation is particularly efficient. Furthermore, the substrate of the electric power module is metallic and does not contain a ceramic layer weakened by thermal cycles.

[0011] An electromechanical actuator is also proposed comprising an electric power module such as that just described and an electric motor.

[0012] The invention will be better understood in light of the following description of a particular, non-limiting embodiment of the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Reference will be made to the attached drawings, including: there figure 1 represents an electrical diagram of an inverter of an electrical power module according to the invention; the figure 2 is a sectional view of the electrical power module according to the invention; the figure 3 is a detail view of the figure 2 ; there figure 4 is a sectional view of a generic power cell of the electrical power module according to an example not forming part of the object of the protection requested; the figure 5 is a sectional view of the electrical power module according to the invention, on which a plastic cover is shown. DETAILED DESCRIPTION OF THE INVENTION

[0014] In reference to the figure 1 , the electrical power module according to the invention 1 comprises power components forming an inverter 2.

[0015] Inverter 2 belongs to an electrical system integrated into an electromechanical actuator.

[0016] In addition to the electrical system, the electromechanical actuator comprises a three-phase electric motor 3 (as well as other elements not shown, and in particular an actuating member). The motor 3 is powered and controlled via the inverter 2.

[0017] In addition to inverter 2, the electrical system includes a connecting circuit 4 and an additional module 5.

[0018] The connecting circuit 4 comprises a connecting capacitor 6, a first connecting component 7 and a second connecting component 8.

[0019] The connection circuit 4 is connected to a power generator, not shown in the figure 1 , which produces a positive DC supply voltage on a positive supply conductor 10, and a negative DC supply voltage on a negative supply conductor 11. The power generator also produces an electric supply current Ial which flows on the positive supply conductor 10 and on the negative supply conductor 11.

[0020] The connecting capacitor 6 is connected in parallel between the positive supply conductor 10 and the negative supply conductor 11.

[0021] The first connecting component 7, represented by an impedance, is mounted on the positive supply conductor 10. The second connecting component 8, represented by an impedance, is mounted on the negative supply conductor 11.

[0022] The additional module 5 comprises, in a conventional manner, a control circuit 13, a monitoring circuit 14, a protection circuit 15 and a measuring circuit 20. The circuits of the additional module 5 are used in particular to control the inverter 2 and therefore the motor 3, and to monitor and protect the inverter 2 and the motor 3.

[0023] The power components of the inverter 2 comprise a capacitor 18 connected in parallel between the positive supply conductor 10 and the negative supply conductor 11, as well as three bridge arms 16 connected in parallel and each comprising two JFET type transistors 21. In the same bridge arm 16, the two transistors 21 cut the signal alternately in the same operating phase during the sequential actuation of their trigger.

[0024] A diode 22 is mounted between the drain and the source of each transistor 21.

[0025] We thus define a first bridge arm 16a comprising a first transistor 21a, a first diode 22a, a second transistor 21b, a second diode 22b, a second bridge arm 16b comprising a third transistor 21c, a third diode 22c, a fourth transistor 21d, a fourth diode 22d, and a third bridge arm 16c comprising a fifth transistor 21e, a fifth diode 22e, a sixth transistor 21f, a sixth diode 22f.

[0026] A first midpoint P1 is located on the first bridge arm 16a between the first transistor 21a and the second transistor 21b. A second midpoint P2 is located on the second bridge arm 16b between the third transistor 21c and the fourth transistor 21d. A third midpoint P3 is located on the third bridge arm 16c between the fifth transistor 21e and the sixth transistor 21f.

[0027] The first midpoint P1 is connected to a first phase Ph1 of motor 3, the second midpoint P2 is connected to a second phase Ph2 of motor 3, and the third midpoint P3 is connected to a third phase Ph3 of motor 3.

[0028] The gates of the transistors 21 are connected to the control circuit 13 of the additional module 5. The control circuit 13 generates electrical control currents Ic under electrical control voltages Vc applied to the gates of the transistors 21 to control the transistors 21 and therefore the motor 3.

[0029] The drains of the first transistor 21a, the third transistor 21c and the fifth transistor 21e are connected to the positive supply conductor 10.

[0030] The sources of the second transistor 21b, the fourth transistor 21d and the sixth transistor 21f are connected to the negative supply conductor 11.

[0031] The sources of the first transistor 21a, the third transistor 21c and the fifth transistor 21e are connected respectively to the drain of the second transistor 21b, to the drain of the fourth transistor 21d and to the drain of the sixth transistor 21f.

[0032] A first phase current Ip1, destined for the first phase Ph1 of the motor 3, is produced by the first bridge arm 16a. A second phase current Ip2, destined for the second phase Ph2 of the motor 3, is produced by the second bridge arm 16b. A third phase current Ip3, destined for the third phase Ph3 of the motor 3, is produced by the third bridge arm 16c.

[0033] The first phase current Ip1, the second phase current Ip2 and the third phase current Ip3 are alternating output currents of the inverter 2, which supply the motor 3.

[0034] In reference to the figure 2 , the electrical power module 1 comprises supports 30 which carry the power components of the inverter 2.

[0035] The supports 30 are assembled together so that the electrical power module 1 has a generally tubular external shape of circular section and longitudinal axis X.

[0036] The supports 30 here comprise a first support 30a, a second support 30b, a third support 30c, a fourth support 30d, a fifth support 30e and a sixth support 30f.

[0037] There figure 2 is a sectional view of the electrical power module along a plane parallel to the X axis and including the X axis.

[0038] In the view of the figure 2 , the first support 30a has the shape of a T. The first support 30a comprises a first metal portion 31 and a second metal portion 32 oriented relative to each other at an orientation angle greater than 0°. Here, the first metal portion 31 and the second metal portion 32 are orthogonal to each other.

[0039] The second support 30b, the third support 30c and the fourth support 30d have the shape of a right angle. The second support 30b, the third support 30c and the fourth support 30d thus each comprise a first metal portion 31 and a second metal portion 32 oriented relative to each other by an orientation angle greater than 0°. Here, the first metal portion 31 and the second metal portion 32 are orthogonal to each other.

[0040] The fifth support 30e has the shape of an F and comprises a first metal portion 31, a second metal portion 32 and a third metal portion 33.

[0041] The second metal portion 32 of the fifth support 30e, the first metal portion 31 and the third metal portion 33 of the fifth support 30e are oriented relative to each other by an orientation angle greater than 0°.

[0042] In this case, the second metal portion 32 of the fifth support 30e is orthogonal to the first metal portion 31 and to the third metal portion 33 of the fifth support 30e.

[0043] The sixth support 30f has a rectilinear shape and comprises a first metal portion 31.

[0044] The first metal portions 31 of the supports 30 are parallel to each other and to the X axis.

[0045] The second metal portions 32 of the supports 30 are parallel to each other and are orthogonal to the X axis.

[0046] The orientation of the metal portions between them is carried out here at the time of manufacture of the electrical power module.

[0047] This orientation allows for optimized integration of the electrical power module into a housing or any environment. In particular, access to the inputs and outputs of the electrical power module and, in particular, to the input connectors and output connectors located on the metal portions of the supports can be freely oriented in space.

[0048] The first transistor 21a and the first diode 22a are both attached to the second metal portion 32 of the first support 30a and to the second metal portion 32 of the second support 30b by being positioned between said second metal portions 32.

[0049] One face of the first transistor 21a and one face of the first diode 22a are fixed, by sintering a sintering material comprising a silver powder, to the second metal portion 32 of the first support 30a.

[0050] The first support 30a is thus electrically connected to the drain of the first transistor 21a and to the cathode of the first diode 22a

[0051] Another face of the first transistor 21a and another face of the first diode 22a are fixed, by sintering the sintering material, to the second metal portion 32 of the second support 30b.

[0052] The second support 30b is thus electrically connected to a source of the first transistor 21a and to an anode of the first diode 22a.

[0053] The second transistor 21b and the second diode 22b are attached in the same way to the second metal portions 32 of the second support 30b and the third support 30c.

[0054] The second support 30b is thus electrically connected to a source of the second transistor 21b and to an anode of the second diode 22b. The third support 30c is thus electrically connected to a drain of the second transistor 21b and to a cathode of the second diode 22b.

[0055] The fourth transistor 21d and the fourth diode 22d are attached in the same manner to the second metal portions 32 of the third support 30c and the fourth support 30d.

[0056] The third support 30c is thus electrically connected to a drain of the fourth transistor 21d and to a cathode of the fourth diode 22d. The fourth support 30d is thus electrically connected to a source of the fourth transistor 21d and to an anode of the fourth diode 22d.

[0057] The third transistor 21c and the third diode 22c are fixed in the same way to the second metal portions 32 of the fourth support 30d and the fifth support 30e.

[0058] The fourth support 30d is thus electrically connected to a source of the third transistor 21c and to an anode of the third diode 22c. The fifth support 30e is thus electrically connected to a drain of the third transistor 21c and to a cathode of the third diode 22c.

[0059] The sixth transistor 21f and the sixth diode 22f are fixed in the same way to the second metal portions 32 of the third support 30c and the sixth support 30f.

[0060] The third support 30c is thus electrically connected to a drain of the sixth transistor 21f and to a cathode of the sixth diode 22f. The sixth support 30f is thus electrically connected to a source of the sixth transistor 21f and to an anode of the sixth diode 21f.

[0061] The fifth transistor 21e and the fifth diode 22e are fixed in the same way to the second metal portions 32 of the fifth support 30e and the sixth support 30f.

[0062] The fifth support 30e is thus electrically connected to a drain of the fifth transistor 21e and to a cathode of the fifth diode 22e. The sixth support 30f is thus electrically connected to a source of the fifth transistor 21e and to an anode of the fifth diode 22e.

[0063] The finishes of the transistors 21 and the diodes 22, that is to say the metallization of their contacts, can comprise any metallic material, and in particular the following materials: Ag, Au, Pd, Al, Cu, Ni, etc.

[0064] Power electric currents, coming from or going to the transistors 21, circulate in the metal portions 32 of the supports 30.

[0065] Power electric currents include the supply electric current Ial, the first phase current Ip1, the second phase current Ip2 and the third phase current Ip3.

[0066] The first support 30a is connected to the positive supply conductor 10, and the supply current Ial flows in the first metal portion 31 and in the second metal portion 32 of the first support 30a. The drain of the first transistor 21a and the cathode of the first diode 22a are therefore brought to the positive DC supply voltage.

[0067] The fifth support 30e is connected to the positive supply conductor 10, and the supply current Ial flows in the first metal portion 31 and in the second metal portion 32 of the fifth support 30e. The drain of the third transistor 21c and of the fifth transistor 21e, and the cathode of the third diode 22c and of the fifth diode 22e, are therefore brought to the positive DC supply voltage.

[0068] The third support 30c is connected to the negative supply conductor 11, and the supply current Ial flows in the first metal portion 31 and in the second metal portion 32 of the third support 30c. The sources of the second transistor 21b, the fourth transistor 21d and the sixth transistor 21f, and the anodes of the second diode 22b, the fourth diode 22d and the sixth diode 22f are therefore brought to the negative DC supply voltage.

[0069] The first phase current Ip1, the second phase current Ip2 and the third phase current Ip3 flow respectively in the second support 30b, the fourth support 30d and the sixth support 30f, to the first phase Ph1, the second phase Ph2 and the third phase Ph3 of the motor 3 respectively.

[0070] The second support 30b, the fourth support 30d and the sixth support 30f are at least partially covered with ferromagnetic ceramic 34. The ferromagnetic ceramic 34 forms, on these supports, high-frequency interference filters. The ferromagnetic ceramic is applied by the technique of “additive manufacturing”, or via a 3D-MID technology (for 3D-Mechatronic Integrated Devices ).

[0071] The thickness Es of at least one support 30 is such that: 5 . Ep < Es < 30 . Ep , where Ep is an average thickness of the chips of the power components mounted on said support 30.

[0072] In reference to the figure 3 , we note that the first support 30a, the third support 30c, the fifth support 30e and the sixth support 30f also carry tracks 35 on which the electric control currents Ic circulate to the gates of the transistors 21.

[0073] Each transistor 21 has a first face 36 comprising a first conductive element connected to the drain of the transistor 21 and a second conductive element connected to the gate of the transistor 21, and a second face 37 comprising a third conductive element connected to the source of the transistor 21.

[0074] As seen earlier, the sintering material 38 is disposed on the first conductive element, the second conductive element and the third conductive element.

[0075] Between the sintering material 38 disposed on the second conductive element and the metal portion 32, there is a track 35 and an insulating layer 39. The insulating layer 39 insulates the track 35 from the metal portion 32 of the support 30 on which the power current (supply current or phase current) flows.

[0076] Track 35 here comprises a conductive material comprising silver and an oxide. The conductive material is dispersed in a screen-printable binder.

[0077] The insulating layer 39 here comprises an inorganic insulating material of the glass frit type. The inorganic insulating material is dispersed in a screen-printable binder.

[0078] The electrical power module 1 allows heat dissipation via an isotropic energy transfer between the transistors 21 through the substrate constituted by the supports 30.

[0079] Heat dissipation is a simultaneous tri-modal dissipation, by conduction, convection and radiation. Heat dissipation can be configurable, by using a thermally conductive element to manufacture the supports 30, the contours of which promote good emissivity. The “additive manufacturing” technique will be advantageously used to form these contours.

[0080] It is further noted that electrical components are arranged on the outer surface of the electrical power module 1. The electrical components include the connecting capacitor 6, as well as a component 40 and a chip 41. The chip 41 is connected via a “wire wiring” 42 (or wire bonding ) to a track 43. The substrate 44 on which these electrical components are mounted is this time a traditional substrate.

[0081] In reference to the figure 4 , the arrangement of the supports 30 is based on a generic power cell 45 which comprises the first support 30a, the second support 30b and the third support 30c. It is noted that, on the figure 4 , the second support 30b and the third support 30c are provided with heat dissipation fins 46 which promote the cooling of the electrical power module.

[0082] This generic cell 45, which forms a bridge arm 16 comprising a first transistor 48a and a second transistor 48b, can be duplicated as many times as necessary to create any power function.

[0083] It is noted that the first transistor 48a and the second transistor 48b are positioned on either side of the second support 30b while being superimposed and centered relative to each other. A distance d between a first axis Za perpendicular to a face of the first transistor 48a and passing through a center of said face, and between a second axis Zb perpendicular to a face of the second transistor 48b and passing through a center of said face, is less than or equal to one third of a diagonal of the face having a larger surface area.

[0084] This generic cell 45 can be configured differently, that is to say that the supports 30 can have different shapes, or be arranged differently with respect to each other.

[0085] A plurality of generic cells 45 of various shapes can be used to produce a power electrical module 1 conforming to any type of integration requirement.

[0086] In reference to the figure 5 , the electrical power module 1 comprises a waterproof cover 50, made of plastic, of tubular shape. The cover 50 is here fixed to the second support 30b, to the third support 30c, to the fourth support 30d and to the fifth support 30e.

[0087] The supports 30 and the cover 50 define a channel 51 inside the electrical power module 1.

[0088] A cooling fluid Fr, for example a gas or a heat transfer liquid, thus circulates in the channel 51 defined by the supports 30 and by the cover 50. The fluid passes through the second support 30b, the third support 30c and the fourth support through orifices 52 made in these supports. The circulation of the cooling liquid in the channel 51 makes it possible to cool the electrical power module 1 very efficiently.

[0089] The cooling fluid provides insulation for the electrical power module. The circulation speed of the cooling fluid is approximately 0.001 m / s. The circulation speed ensures that no partial discharges occur during electrical switching of the switches formed by the transistors 21.

[0090] The contours of the supports 30 are sized to promote a large exchange surface with the cooling fluid.

[0091] Advantageously, the supports 30 and, in particular, the first metal portions 31 and the second metal portions 32, are manufactured using the additive manufacturing technique. The material used is, for example, aluminum. It is thus possible to define cooling channels inside the first metal portions 31 and the second metal portions 32 of the supports 30.

[0092] The thermal performance obtained is inversely proportional to the diameter of the cooling channels, but the balance of hydraulic pressure losses is proportional to the diameter of the cooling channels.

[0093] For cooling channel diameters between 10µm and 800µm, we refer to micro-channel heat exchangers. For cooling channel diameters between 1mm and 10mm, we refer to mini-channel heat exchangers. For cooling channel diameters greater than 10mm, we refer to cold plates.

[0094] During the manufacture of the electrical power module, a first insulator is first applied by screen printing in a thick layer on each face of the supports 30 carrying the transistors 21. Then, the components are mounted on the supports 30, and the electrical power module is assembled. A second insulator is then deposited by a plasma process, by vapor deposition, by evaporation or by rolling. This forms a crack-free and bubble-free coating, which has thickness variations of less than 1 µm. This coating covers and insulates all the internal and external surfaces of the electrical power module.

[0095] The electrical power module is finally covered with a resin or integrated into a protective packaging. This preserves the electrical insulation from external mechanical stresses likely to cause scratches, impacts, crushing, etc. The input and output connectors, allowing the electrical power module to be connected to a motor or other equipment, are left free.

[0096] Of course, the invention is not limited to the embodiment described but encompasses any variant falling within the scope of the invention as defined by the claims.

[0097] The electrical power module described here comprises an inverter, but the invention can of course be applied to any type of electrical power module implementing any type of power function.

[0098] The number of bridge arms could of course be different, as could the power components used.

[0099] Although it has been stated that the components are attached to the supports by sintering, a different means of attachment could be used, for example soldering or gluing.

[0100] It has been described here that the first metal portions 31 and the second metal portions 32 are orthogonal to each other. A first metal portion and a second metal portion oriented of at least one support could however be oriented relative to each other by a different orientation angle, greater than 0°.

[0101] It has also been indicated that the orientation of the metal portions is carried out at the time of manufacture of the electrical power module. It is also possible to provide for the orientation angle(s) to be adjusted at the time of integration of the electrical power module into a housing containing said electrical power module. The metal portions are then fixed together by fixing means allowing the adjustment of the orientation angle.

Claims

1. An electrical power module comprising power components (21, 22) and supports (30), each comprising at least one metal portion (31; 32), the metal portions of the supports forming a substrate of the electrical power module (1), each power component being fastened to two metal portions of two distinct supports by being positioned between said two metal portions, the electrical power module being arranged in such a manner that electrical power currents going to or coming from the power components flow in the metal portions of the supports, at least one support (30c, 30e) comprising two angled metal portions that are angled relative to each other at an angle that is greater than 0°, characterized in that the two angled metal portions are mutually orthogonal, and in that a distinct power component being fastened to each of said two angled metal portions.

2. An electrical power module according to claim 1, wherein the two angled metal portions are arranged in such a manner that the angle between them can be adjusted when the electrical power module is integrated in a housing.

3. An electrical power module according to claim 1, wherein the power components include controllable components (21), the electrical power module including tracks (35) for conveying electrical control currents (Ic) for the controllable components, each track being positioned between two metal portions of two distinct supports, each track being insulated from a metal portion (32) of a support (30) by an insulating layer (39).

4. An electrical power module according to claim 3, wherein at least one of the tracks (35) comprises a conductive material including silver and an oxide, the conductive material being dispersed in a binder suitable for silk-screen printing.

5. An electrical power module according to claim 3, wherein at least one of the insulating layers (39) comprises an inorganic insulating material of the glass frit type, the inorganic insulating material being dispersed in a binder suitable for silk-screen printing.

6. An electrical power module according to claim 1, wherein one face of each power component (21, 22) is fastened to a metal portion of a support by sintering.

7. An electrical power module according to claim 1, wherein the supports are partially covered in ferromagnetic ceramic (34) forming lowpass filters.

8. An electrical power module according to claim 1, wherein the supports define a channel (51) inside the electrical power module, the electrical power module being arranged in such a manner that a fluid flows in the channel (51) in order to cool the electrical power module.

9. An electrical power module according to claim 8, further including a leak-tight plastics material cover (50) that also defines the channel, the cover being fastened to supports.

10. An electrical power module according to claim 1, wherein the supports (30) are fabricated by using an additive fabrication technique.

11. An electrical power module according to claim 1, wherein cooling channels are defined inside the supports (30).

12. An electrical power module according to claim 1, including at least three supports (30).

13. An electrical power module according to claim 1, wherein a support (30) is of a thickness Es such that: 5 . Ep < Es < 30 . Ep where the chips of the power components mounted on said support (30) present a mean thickness of Ep.

14. An electrical power module according to claim 1, the power components include two transistors (21) and two diodes (22) forming a single bridge arm (16), the electrical power module including a first support (30a) in which there flows an power supply electric current at a positive DC power supply voltage, a second support (30b) in which there flows an AC output current, and a third support (30c) in which there flows an power supply electric current at a negative DC power supply voltage.

15. An electrical power module according to claim 14, including a first transistor (48a) and a second transistor (48b) forming a single bridge arm, the first transistor (48a) and the second transistor (48b) being positioned on either side of a single support (30b) so as to be superposed and centered relative to each other.

16. An electrical power module according to claim 15, wherein a first axis (Za) perpendicular to a face of the first transistor (48a) and passing through the center of said face is spaced apart from a second axis (Zb) perpendicular to a face of the second transistor (48b) and passing through the center of said face by a distance (d) that is less than or equal to one third of the length of a diagonal of the face having the larger area.

17. An electromechanical actuator comprising an electrical power module according to claim 15 and an electric motor (3).