KR20220113415A - Electrical Assemblies and Voltage Converters - Google Patents

Abstract

The present invention relates to an electrical assembly comprising: a heat sink 704, a first "main" electrical conductor 106B, a first electrical component 112 mounted to a first surface of the first main electrical conductor 106B , and an electrical insulator 302 hermetically sealing the first main electrical conductor 106B and the electrical component 112, the electrical insulator 302 comprising a first main electrical conductor ( 106B) has an opposing top surface 304 , wherein the electrical circuit 110 is bonded to the heat sink 704 via an electrically insulating connection element 900 , and an upper surface of the electrical insulator 302 . A fire protection element that extends for at least 85% of the portion 604 of the 304 or extends a predefined distance from at least 85% of the portion 604 of the upper face 340 of the electrical insulator 302 . element 404 , wherein this portion 604 includes one or more points of the top surface 304 of the electrical insulator 302 closest to the first electrical component 112 .

Description

Electrical Assemblies and Voltage Converters

The present invention relates to an electrical assembly and a voltage converter comprising such an electrical assembly.

A known electrical assembly includes an electrical circuit positioned against a heat sink and comprising a first "main" electrical conductor, a first electrical component mounted to a first surface of the first main electrical conductor, and a first main electrical conductor. an electrical insulator hermetically sealing the conductor and the electrical component, the electrical insulator having a top surface opposite the first main electrical conductor.

However, in case of overheating of the first electrical component, for example a short circuit in the case of a controllable switch, there is a risk that the heat will diffuse into the electrical insulator and catch fire on its upper side, endangering the surrounding elements.

It is an object of the present invention to at least partially overcome the above-mentioned problems.

To this end, according to a first aspect of the invention, there is provided an electrical assembly comprising a heat sink, an electrical circuit and a fire protection element, said electrical circuit comprising:

- a first "main" electrical conductor,

- a first electrical component mounted on a first surface of the first main electrical conductor;

- an electrical insulator hermetically sealing the first main electrical conductor and the electrical component, the electrical insulator having an upper side opposite the first main electrical conductor;

the electrical circuit is bonded to the heat sink via an electrically insulating connecting element, the fire protection element extending over at least 85% of a portion of the upper face of the electrical insulator or preliminarily from at least 85% of a portion of the upper face of the electrically insulator Extending a defined distance, this portion includes one or more points on the top face of the electrical insulator closest to the first electrical component.

Thus, by means of the fire protection element, the spread of the fire is stopped or at least limited.

The electrical assembly according to the first aspect of the invention may further comprise one or more of the features of the specific embodiments below, which are considered individually or in any technically possible combination.

In one particular embodiment of the invention, the electrical circuit is a power module.

In one particular embodiment of the invention, the first main electrical conductor is a busbar.

In one particular embodiment of the invention, the first main electrical conductor is a busbar configured to be connected to a high potential of an electrical power source.

In one particular embodiment of the invention, the second main electrical conductor is a busbar configured to be connected to a phase of a rotating electrical machine.

In one particular embodiment of the invention, the second main electrical conductor comprises first and second “partial” electrical conductors, said first and second partial electrical conductors being busbars.

In one particular embodiment of the invention, the third main electrical conductor is a busbar.

In one particular embodiment of the invention, the third main electrical conductor is a busbar configured to be connected to a low potential of an electrical power source.

In one particular embodiment of the invention, the first main electrical conductor and/or the third main electrical conductor take the shape of a horizontal flat plate, for example having a thickness between 1 mm and 2 mm.

In one particular embodiment of the invention, the first main electrical conductor and the third main electrical conductor take the shape of two coplanar plates extending side by side.

In one particular embodiment of the present invention, the first main electrical conductor and/or the second partial electrical conductor and/or the third main electrical conductor are in the shape of a horizontal flat plate, for example having a thickness between 1 mm and 2 mm. take

In one particular embodiment of the invention, the first main electrical conductor, the second partial electrical conductor and the third main electrical conductor take the shape of coplanar plates extending side by side.

In one particular embodiment of the present invention, the second surface of the first electrical conductor opposite the first surface to which the first electrical component is mounted has a portion not covered by an electrical insulator, said portion being connected to said electrical insulator. It is attached to the heat sink via an electrically insulating connecting element not covered by the

In one particular embodiment of the invention, the electrically insulating connecting element comprises particles of a solid material.

In one particular embodiment of the invention, the particles of solid material each have a diameter greater than a predefined value.

In one specific embodiment of the present invention, the electrically insulating connecting element comprises an electrically insulating sheet or plate interposed between the heat sink and the portion not covered by the electrical insulator.

In one specific embodiment of the present invention, the electrically insulating sheet or plate inserted between the portion not covered by the electrical insulator and the heat sink is made of graphite or ceramic.

In one particular embodiment of the present invention, the surface of the heat sink to which the portion not covered by the electrical insulator is attached is formed of a film of electrically insulating material.

In one particular embodiment of the present invention, the surface of the heat sink to which the electrical circuit is attached is formed of a film of electrically insulating material.

In one specific embodiment of the present invention, the film of electrically insulating material is obtained, for example, by anodizing the surface of the heat sink to which the electrical circuit is attached.

In one specific embodiment of the present invention, the surface of the portion not covered by the electrical insulator is formed of a film of electrically insulating material.

In one specific embodiment of the present invention, the heat sink is made of aluminum or an aluminum alloy, and the electrically insulating film is formed by an oxidized film.

In one particular embodiment of the invention, the electrical insulator has a lower face, and/or the lower face, and/or the surface of the heat sink to which the electrical circuit is attached, comprises a protrusion that controls the thickness of the electrical connection element.

In one particular embodiment of the invention, the predefined distance is less than 1 mm, preferably less than 0.5 mm, even more preferably less than 0.2 mm.

The distance between the fire protection element and the upper surface of the electrical insulator is preferably as small as possible in order to stop the spread of the fire as close as possible to the electrical component. However, it is possible to insert a layer of adhesive or resin between the fire protection element and the upper face of the electrical insulator, in particular in order to promote a good distribution of the bearing force between the fire protection element and the electrical insulator. The distance between the fire protection element and the upper surface of the electrical insulator of less than 1 mm, preferably less than 0.5 mm and even more preferably less than 0.2 mm allows the fire protection element to maintain a good degree of ability to stop or limit the spread of fire.

In one particular embodiment of the invention, the fire protection element is made of metal, for example steel.

In one particular embodiment of the invention, the fire protection element is in the shape of a plate.

In one specific embodiment of the present invention, the electrical insulator is an epoxy resin. Thus, the electrical insulator is sufficiently rigid to form the protective casing.

In one particular embodiment of the invention, the electrical circuit further comprises a second “main” electrical conductor and at least one electrical connection configured to connect the first electrical component to the second main electrical conductor, each The electrical connection has an electrically conductive section that is at least ten times smaller than the electrically conductive section of the first main electrical conductor.

In one particular embodiment of the present invention, the electrical assembly further comprises a magnetic torus and the electrical circuit further comprises a second electrical component mounted to the first surface of the second main electrical conductor, the second The main electrical conductor includes first and second “partial” electrical conductors electrically connected to each other, and the magnetic torus is wound around the second partial electrical conductor.

In one particular embodiment of the present invention, the electrical insulator hermetically seals the first main electrical conductor, the first electrical component and the second main electrical conductor.

In one specific embodiment of the present invention, the electrical insulator hermetically seals the first main electrical conductor, the second main electrical conductor, the third main electrical conductor, the first electrical component and the second electrical component.

In one particular embodiment of the invention, the electrical circuit further comprises at least one second electrical connection configured to connect the second electrical component to a third “main” electrical conductor, each second electrical connection being 2 having an electrically conductive section that is at least 10 times smaller than the electrically conductive section of the main electrical conductor.

In one particular embodiment of the invention, the second partial electrical conductor is electrically connected to the first partial electrical conductor by soldering, brazing or screwing.

In one particular embodiment of the invention, the electrical assembly further comprises an overmolding of plastic material surrounding the magnetic torus and the second partial electrical conductor, wherein the fire protection element is attached to the overmolding of the plastic material.

In one particular embodiment of the invention, the fire protection element has at least one tongue, each tongue being overmolded in an overmolding of plastic material for attaching the fire protection element to the overmolding of the plastic material.

In one particular embodiment of the invention, the electrical assembly further comprises an overmolding of plastic material surrounding the magnetic torus and the second partial electrical conductor, wherein the fire protection element comprises a lower face of the overmolding of plastic material and an upper portion of the electrical insulator. inserted between the sides.

In one particular embodiment of the present invention, the overmolding of plastic material surrounding the magnetic torus comprises at least one stud projecting from a lower face of the overmolding, the fire protection element comprises at least one hole, and the electrical insulator comprises: the upper surface of the shroud comprises at least one cavity, the studs being connected to the first partial electrical conductor for retaining the fire protection element between the lower surface of the overmolding of the plastic material and the upper surface of the electrical insulator, the second partial electrical conductor being connected to the first partial electrical conductor. configured to insert into the aperture and the cavity when electrically connected.

In one particular embodiment of the invention, the first electrical component and/or the second electrical component are controllable switches, for example insulated-gate field-effect transistors.

In one particular embodiment of the invention, the heat sink comprises at least one cavity, and the electrical circuit is located at the bottom of the cavity.

In one particular embodiment of the present invention, the cavity of the heat sink is at least partially filled with an electrical insulator, gel or epoxy resin to at least partially cover the electrical circuit.

In one specific embodiment of the present invention, the cavity of the heat sink is at least partially filled with an electrical insulator, gel or epoxy resin to completely cover the electrical circuit.

In one particular embodiment of the invention, the insulator or gel is non-flammable or non-combustible, or comprises a flame retardant.

Also according to a second aspect of the present invention there is provided a voltage converter comprising an electrical assembly according to the first aspect of the present invention.

In one particular embodiment of the invention, the voltage converter further comprises a component, and the fire protection element has at least one flexible blade configured to be deformed by the component to press the electrical circuit against a heat sink.

In one particular embodiment of the invention, the voltage converter further comprises a component, wherein the fire protection element has at least one blade configured to be deformed by the component to press the electrical circuit against the bottom of the cavity of the heat sink. .

BRIEF DESCRIPTION OF THE DRAWINGS The invention will be better understood in light of the following description provided by way of example only and with reference to the following drawings.

1 is a circuit diagram of an electrical system embodying the present invention.
FIG. 2 is a three-dimensional view of the power module of the voltage converter of the electrical system of FIG. 1 without overmolding or fire protection elements;
3 is a three-dimensional view of a first sub-module of a power module;
4 is a three-dimensional view of a second sub-module of the power module;
Fig. 5 is a view similar to Fig. 4, without overmolding;
6 is a partial cross-sectional view of the power module, showing the arrangement of the fire protection element;
7 is a cross-sectional view of the voltage converter showing the position of the power module.
8 is a block diagram illustrating a method of manufacturing a power module.

An electrical system 100 embodying the present invention will now be described with reference to FIG. 1 .

The electrical system 100 is configured for installation in a motor vehicle, for example.

Electrical system 100 first has a power source 102 designed to deliver a DC voltage U, for example between 20V and 100V, for example 48V. The power source 102 has, for example, a battery.

The electrical system 100 further includes an electrical machine 130 that includes a plurality of phases (not shown) configured to have respective phase voltages.

The electrical system 100 further includes a voltage converter 104 coupled between the power source 102 and the electrical machine 130 to perform conversion between the DC voltage U and the phase voltage.

The voltage converter 104 first includes a positive busbar 106 and a negative busbar 108 configured to be coupled to a power supply 102 for receiving a DC voltage U, the positive busbar 106 having a high potential. , and the negative busbar 108 receives a low potential.

The voltage converter 104 further comprises at least one power module 110 comprising one or more phase busbars 122 each configured to be connected to one or more phases of the electrical machine 130 to provide their respective phase voltages. include

In the described embodiment, the voltage converter 104 includes three power modules 110 each including two phase busbars 122 connected to the two phases of an electrical machine 130 .

More precisely, in the described embodiment, the electrical machine 130 comprises two three-phase systems each comprising three phases. The two three-phase systems are configured to be 120° electrically phase-offset from each other. Preferably, the first phase busbars 122 of the power module 110 are respectively connected to the three phases of the first three-phase system, while the second phase busbars 122 of the power module 110 are connected to the second and third phases respectively. Each of the three phases of the phase system is connected.

Each power module 110 includes, for each phase busbar 122 , a high-side switch 112 connected between the positive busbar 106 and the phase busbar 122 , and and a low-side switch 114 coupled between the upper busbar 122 and the negative busbar 108 . Accordingly, the switches 112 and 114 are arranged such that the phase busbar 122 forms a switching arm forming a center tap.

Each of the switches 112 and 114 selectively switches the switches 112 and 114 between the first and second main terminals 116 and 118 and the two main terminals 116 and 118 according to a control signal applied thereto. and a control terminal 120 configured to open and close. Switches 112 and 114 are preferably transistors, for example metal oxide semiconductor field-effect transistors (MOSFETs) having a gate forming a control terminal 120, and a drain and a source forming the main terminals 116 and 118, respectively. )to be.

In the described embodiment, each of the switches 112 , 114 is, for example, substantially rectangular and has the form of a plate having an upper side and a lower side. The first main terminal 116 extends over the lower surface, while the second main terminal 118 extends over the upper surface.

It will be appreciated that positive busbar 106 , negative busbar 108 and phase busbar 122 are rigid electrical conductors designed to withstand a current of at least 1A. They preferably have a thickness of at least 1 mm and/or an electrically conductive section of at least 1 mm 2 .

Also, in the described embodiment, the positive busbar 106 is first connected to the positive common busbar 106A connecting the power modules 110, and in each power module 110, to the positive common busbar 106A. and a connected positive local busbar 106B. Similarly, the negative busbar 108 is a negative common busbar 108A connecting the power modules 110 , and in each power module 110 , a negative local bus for each low-side switch 114 . bar 108B, with negative local busbar 108B connected to negative common busbar 108A. Connections are marked with diamonds in FIG. 1 .

Also, in the described embodiment, the positive common busbar 106A and the negative common busbar 108A are each formed of a single conductive component.

Also, in the described embodiment, the electric machine 130 has both an alternator function and an electric motor function. More specifically, the motor vehicle further includes a combustion engine (not shown) having an output shaft to which the electrical machine 130 is connected via a belt (not shown). The combustion engine is configured to drive the wheels of a motor vehicle by way of its output shaft. Thus, while operating as an alternator, the electrical machine delivers electrical energy to the power source 102 based on the rotation of the output shaft. The voltage converter 104 then operates as a rectifier. While operating as an electric motor, the electric machine drives an output shaft (in addition to or instead of a combustion engine). Next, the voltage converter 104 operates as an inverter.

The electric machine 130 is located, for example, in a gearbox or in fact in a clutch of a motor vehicle or in fact instead of an alternator.

Throughout the remainder of the description, the structure and layout of the elements of the voltage converter 104 will be described in greater detail with reference to the vertical direction H-B, where “H” represents the top and “B” represents the bottom.

2-7, one of the power modules 110 will now be described in more detail, note that the other power modules 110 are similar.

Referring to FIG. 2 , the power module 110 includes first and second sub-modules.

The first sub-module includes a positive local busbar 106B and a negative local busbar 108B. It further comprises, for each phase busbar 122 , a partial busbar 202 forming part of this phase busbar 122 . It further includes switches 112 and 114 .

The busbars 106B, 202, 108B have a thickness of between 1 mm and 2 mm, for example 1.5 mm, and take the form of a horizontal flat plate with a horizontal planar top surface. In addition, the busbars 106B, 202 and 108B are coplanar and may extend laterally to each other to limit the vertical bulk of the power module 110 .

The lower surface of each high-side switch 112 is pressed against the upper surface of the positive local busbar 106B and soldered to the positive local busbar 106B to mechanically attach the high-side switch 112 . . This attachment also makes it possible to electrically connect the first main terminal to the positive local busbar 106B. Further, the first sub-module is configured for, for each high-side switch 112 , each of the partial busbars 202 to electrically connect the partial busbar from the top surface of the high-side switch 112 . It comprises a plurality of conductive strips 210 extending up to one, for example made of aluminum. The conductive strip 210 preferably has an electrically conductive section that is at least 10 times smaller than the electrically conductive section of the busbars 106B, 202, 108B.

Similarly, the lower surface of each low-side switch 114 is pressed against the upper surface of the partial busbar 202 to mechanically attach the low-side switch 114 and to the partial busbar 202 . are soldered This attachment also makes it possible to electrically connect its first main terminal to the phase busbar 122 .

In addition, the first sub-module is, for each low-side switch 114, a low-side switch ( one or preferably a plurality of conductive strips 212 , for example made of aluminum, extending to each one of 114 . The conductive strip 212 preferably has an electrically conductive section that is at least ten times smaller than the electrically conductive section of the busbars 106B, 202, 108B.

The second sub-module comprises another partial busbar 204 attached to the partial busbar 202 by, for example, soldering, brazing or screwing, the two being mechanically attached and electrically connected to each other. Thus, each phase busbar 122 includes two partial busbars 202 , 204 .

Except for their ends, the partial busbars 204 also take the form of horizontal flat plates having a thickness of between 1 mm and 2 mm, for example 1.5 mm. One of the ends of the partial busbar 204 may take a curved shape to facilitate their attachment to the partial busbar 202 .

The partial busbar 204 further includes a connection terminal 206 configured to be connected to the phase of the electric machine 130 . In general, the shape of the connection terminal 206 is linked to the shape of the phase terminal of the electric machine 130 .

The second sub-module comprises around each partial busbar 204 a magnetic torus 208 provided with an air gap, wherein a Hall effect sensor (not shown) detects the phase current flowing through the corresponding connection terminal 206 . configured to be placed to measure.

Referring to FIG. 3 , a first sub-module denoted by reference numeral 200 includes a positive local busbar 106B, a negative local busbar 108B, a partial busbar 202, a switch 112, and a switch 112 to protect them. 114 ) and an epoxy resin overmolding 302 extending around the conductive strips 210 , 212 . Thus, the epoxy resin overmolding 302 forms an electrical insulator covering the busbars 106B, 202, 108B and switches 112, 114, among others. The epoxy resin overmolding 302 has a top surface 304 opposite the busbars 106B, 202, 108B. This upper surface 304 is planar and horizontal. The material used for the overmolding 302 has, for example, a flex limit of greater than 80 N/mm 2 , preferably a flex limit of greater than 100 N/mm 2 . For example, the material used for the overmolding 302 may be an epoxy resin marked with G720E type H with a flex limit of 140 N/mm 2 , or an epoxy resin marked with XE8495 with a flex limit of 105 N/mm 2 .

Referring to FIG. 6 , the lower surface of the positive local bus bar 106B opposite the upper surface of the positive local bus bar 106B on which the switch 112 is mounted is not covered by the overmolding of the epoxy resin 302 . (S1). Similarly, the lower surface of the partial busbar 202 opposite the upper surface of the partial busbar 202 to which the switch 114 is mounted has a portion S2 uncovered by overmolding of the epoxy resin 302 . .

Referring to FIG. 4 , a second sub-module, denoted by reference numeral 201 , includes a magnetic torus 208 and a partial magnetic torus 208 to retain the magnetic torus 208 mechanically attached to the partial busbar 204 . It further includes an overmolding of the plastic material 402 extending around the busbar 204 . The second sub-module 201 further comprises a fire protection element 404 formed in the embodiment described as a horizontal metal plate attached to and projecting from the lower surface of the overmolding 402 . The metal plate is, for example, a steel plate. The fire protection element 404 preferably has at least one flexible blade 406 (three in the described embodiment) positioned in one of the areas projecting from the underside of the overmolding 402 . In the described embodiment, each flexible blade 406 is rectangular in shape, one end of which is connected to the remainder of the fire protection element 404 by folding upwards. Each flexible blade 406 is obtained, for example, by stamping a metal plate forming the fire protection element 404 . The fire protection element 404 has, for example, a thickness between 0.5 mm and 1 mm.

Thus, the complete power module 110 includes a first sub-module 200 shown in FIG. 3 and a second sub-module 201 shown in FIG. 4 attached to each other.

Referring to FIG. 5 , the fire protection element 404 further includes three tongues 502 configured to be embedded in the overmolding 402 for attaching the fire protection element 404 thereto.

Referring to FIG. 6 , for each switch 112 , 114 , a fire protection element 404 is disposed of a portion 604 of the upper surface 304 of the electrical insulator 302 closest to the switch 112 , 114 in question. At least 85% (100% in the described embodiment) extend within 1 mm, preferably within 0.2 mm. More precisely, this portion 604 (indicated by the bold dashed line in FIG. 6 ) groups together at least points of the top face 304 of the electrical insulator 302 closest to the switches 112 , 114 in question. These points closest to switches 112 and 114 are indicated by reference numeral 606 in FIG. 6 . In the illustrated embodiment, the point closest to the switches 112 , 114 is the point vertically aligned with the switches 112 , 114 . Thus, in the described embodiment, the fire protection element 404 extends at least over the switches 112 , 114 to cover the switches 112 , 114 .

In general, the portion 604 groups together points on the top face 304 of the electrical insulator 302 that are located at a distance equal to or less than a predefined distance D from the switches 112 and 114 in question. This predefined distance D is greater than the thickness E of the overmolding 302 between the switches 112 , 114 in question and the top surface 304 of the overmolding 302 , wherein the thickness E is It corresponds to the minimum distance between the switches 112 , 114 and the top surface 304 of the overmolding 302 . The predefined distance D is for example less than 4 mm. In the described embodiment it is about 2 mm.

In the event of a short circuit of the power module 110, the conductive strips 210, 212 get hotter until they break. However, since they are embedded in a hard epoxy resin, the pieces of conductive strips 210 and 212 are kept in contact so that current can flow. The flowing current then heats the switches 110 , 112 , and the heat spreads to the overmolding 302 and to the ignited top surface 304 . The point closest to each of the switches 110 and 112 is a point at which the temperature rises first due to the proximity of the switches 110 and 112, and accordingly, it is a point to be protected first. Thus, the presence of the fire protection element 404 makes it possible to prevent or at least delay the spread of the fire.

Referring to FIG. 7 , voltage converter 104 includes a casing 702 defining a housing for housing a circuit board (not shown) for controlling switches 112 , 114 , for example a printed circuit board. do. The voltage converter 104 further includes a heat sink 704 configured to dissipate heat from the switches 112 , 114 in particular. The heat sink 704 specifically includes heat dissipation fins 706 . The heat sink 704 further includes a shaft for receiving a screw (not shown) for attaching the casing 702 to the heat sink 704 . The heat sink 704 also includes three cavities 708 .

Each power module 110 is configured to adhere to the bottom of one of the cavities 708 via an electrically insulating connection element 900 to be positioned between the casing 702 and the heat sink 704 .

In the embodiments described herein, the electrically insulating connection element 900 is, for example, a thermal adhesive. In one alternative embodiment, the electrically insulating connecting element is a thermal paste. In another alternative embodiment, the electrically insulating connecting element is a thermal grease.

In the embodiment described herein, the electrically insulating connection element 900 further comprises particles of a solid material (not shown in FIG. 7 ) such as plastic. In this way, the thickness of the electrically insulating connecting element 900 is determined by the diameter of the particles of the solid material. Therefore, the electrically insulating connection element 900 is designed to limit the risk of an electric arc occurring between the heat sink 704 and the exposed surfaces S1 and S2 outside the overmolding of the epoxy resin of the power semiconductor module 110 . It is possible to ensure a sufficient thickness, thereby limiting the risk of fire, in particular when the power module 110 is heated and the electrically insulating connecting element 900 is consequently softened.

In one alternative embodiment of the invention, the electrically insulating connection element 900 is sandwiched between the surfaces S1 and S2 of the power module 110 and the heat sink 704 , for example made of ceramic or graphite. including electrically insulating sheets or plates.

In another alternative embodiment of the present invention, the bottom of the cavity 708 of the heat sink 704 is formed from a film of electrically insulating material obtained, for example, by anodizing the surface of the bottom of the cavity 708 . Accordingly, when the heat sink 704 is made of aluminum or an aluminum alloy, the electrically insulating film is formed by an oxidized film.

In another alternative embodiment of the present invention, the bottom surface of the overmolding of the epoxy resin 302 and/or the surface of the bottom of the cavity 708 of the heat sink 704 to which the power module 110 is attached is an electrical connection element. It includes a protrusion to control the thickness of 900 .

Accordingly, the use of a sheet, electrically insulating plate, electrically insulating material film, or protrusion is an electric arc generated between the heat sink 704 and the exposed surfaces S1 and S2 outside the epoxy resin overmolding of the power semiconductor module 110 . limit the risk of fire as well as the risk of a possible fire.

In the embodiment described herein and once the power module 110 is adhered to the heat sink 704 , the cavity 708 of this heat sink 704 is formed with a gel 950 , to completely cover the power module 110 , For example, it is at least partially filled with a non-flammable or non-combustible gel, or a gel comprising a flame retardant.

As a variant, the cavity 708 is at least partially filled with an electrical insulator or epoxy resin to completely cover the power module 110 .

Thus, in the event of a fire in one of the power modules 110 , the gel, electrical insulator or epoxy resin prevents or at least delays the spread of the fire.

When the casing 702 is attached to the heat sink 704 , the casing 702 is configured to support one or more flexible blades 406 to deform the power module 110 to urge it against the heat sink 704 . do. Preferably, the one or more flexible blades 406 are designed to transmit a normal force of at least 70N to the power module 110 once deformed by the casing 702 . Thus, this pressing can prevent the busbar from moving away from the heat sink 704 over time and the electrical connection element 900 from wearing out. Such pressing may also avoid the use of screws to attach the power module 110 to the heat sink 704 .

Preferably, the circuit board is received in and attached to the casing 702 before the casing 702 is attached to the heat sink 704 and supports the one or more flexible blades 406 .

Referring to FIG. 8 , a method 800 for manufacturing one of the power modules 110 will now be described.

In step 802 , first and second sub-modules 200 , 201 without overmolding 302 , 402 are obtained.

In step 804 , an epoxy resin is injected at low pressure, and then crosslinked to form an epoxy resin overmolding 302 . The low pressure injection makes it possible to prevent damage to the fragile conductive strips 210 , 212 .

In step 806 , a plastic material is injected at high pressure to form an overmolding of the plastic material 402 .

In step 808, the two sub-modules 200, 201 are attached to each other. To this end, the fire protection element 404 is glued to the top face 304 of the epoxy resin overmolding 302 , and the partial busbars 204 are attached to the partial busbars 202 .

The present invention is not limited to the above-described embodiment. Indeed, it will be apparent to those skilled in the art that modifications may be made.

For example, the overmolding 302 may be a material other than an epoxy resin.

Conversely, the fire protection element 404 is not attached to the lower surface of the overmolding 402 and is not adhered to the upper surface 304 of the overmolding of the epoxy resin 302, and the partial busbar 204 is removed in step 808. It can simply be inserted between the lower face of the overmolding 402 and the upper face 304 of the overmolding of the epoxy resin 302 when attached to the partial busbar 202 in . In this particular embodiment, the lower face of the overmolding 402 includes overmolded studs, eg, two numbered and cylindrical studs, which protrude from the lower face of the overmolding 402, and a portion The busbar 204 is configured to be inserted into the cavity of the top face 304 of the overmolding of the epoxy resin 302 when the busbar 204 is attached to the partial busbar 204 in step 808 .

In addition, the terms used should not be construed as being limited to the components of the embodiments described above, but rather should be understood to encompass all equivalent components that those skilled in the art can deduce from their general knowledge.

Claims (15)

An electrical assembly comprising:
a. heat sink 704;
b. A first “main” electrical conductor 106B, a first electrical component 112 mounted to a first surface of the first main electrical conductor 106B, and a first main electrical conductor 106B and electrical component 112 ), an electrical circuit 110 comprising an electrical insulator 302 hermetically sealing the ) bonded to the heat sink 704 via an electrically insulating connecting element 900 , and
c. extend for at least 85% of the portion 604 of the top surface 304 of the electrical insulator 302 or predefined from at least 85% of the portion 604 of the top surface 340 of the electrical insulator 302 . a fire protection element 404 extending a distance - this portion 604 comprising one or more points of the top face 304 of the electrical insulator 302 closest to the first electrical component 112 - containing
electrical assembly. The method of claim 1,
A second surface of the first electrical conductor (106B) opposite the first surface to which the first electrical component (112) is mounted has a portion (S1) not covered by the electrical insulator (302), the electrical insulator The portion S1 not covered by is attached to the heat sink 704 via the electrically insulating connecting element 900 .
electrical assembly. 3. The method according to claim 1 or 2,
The electrically insulating connection element 900 comprises particles of solid material, and/or an electrically insulating sheet or plate sandwiched between a heat sink 704 and a portion not covered by an electrical insulator 302 .
electrical assembly. 4. The method according to any one of claims 1 to 3 and
The surface of the heat sink 704 to which the portion S1 not covered by the electrical insulator 302 is attached is formed of a film of an electrical insulating material.
electrical assembly. 5. The method according to any one of claims 1 to 4,
The electrical insulator (302) has a lower surface, wherein the lower surface and/or the surface of the heat sink (704) to which the electrical circuit is attached comprises a projection controlling the thickness of the electrical connection element (900)
electrical assembly. 6. The method according to any one of claims 1 to 5,
The fire protection element 404 is made of metal, for example steel, and is in the form of a plate.
electrical assembly. 7. The method according to any one of claims 1 to 6,
The electrical circuit further comprises a second "main" electrical conductor (122) and at least one electrical connection (210) configured to connect the first electrical component (112) to the second main electrical conductor (122); Each electrical connection 210 has an electrically conductive section that is at least 10 times smaller than the electrically conductive section of the first main electrical conductor 106B.
electrical assembly. 8. The method of claim 7,
further comprising a magnetic torus (208), the electrical circuit further comprising a second electrical component (114) mounted to a first surface of a second main electrical conductor (122), the second main electrical conductor (122) Conductor 122 includes first and second "part" electrical conductors 202; 204 electrically connected to each other, said magnetic torus 208 being wound around second partial electrical conductor 204.
electrical assembly. 9. The method of claim 8,
an overmolding of a plastic material (402) surrounding the magnetic torus (208) and the second partial electrical conductor (204), wherein the fire protection element (404) is a lower surface of the overmolding of the plastic material (402) and the upper surface of the electrical insulator 302
electrical assembly. 10. The method according to claim 8 or 9,
the overmolding of plastic material (402) surrounding the magnetic torus (208) comprises at least one stud protruding from a lower surface of the overmolding, the fire protection element (404) comprising at least one aperture; The upper surface of the electrical insulator 304 includes at least one cavity, the stud being configured such that the second partial electrical conductor 204 is positioned between the lower surface of the overmolding of plastic material and the upper surface of the electrical insulator. ) configured to be inserted into the aperture and the cavity when electrically connected to a first partial electrical conductor 202 to retain
electrical assembly. 11. The method according to any one of claims 8 to 10,
It further comprises at least one second electrical connection 212 configured to connect the second electrical component 114 to the third “main” electrical conductor 108B, each second electrical connection 212 being a second electrical conductor 108B. having an electrically conductive section that is at least 10 times smaller than the electrically conductive section of the main electrical conductor 122 .
electrical assembly. 12. The method according to any one of claims 8 to 11,
The second partial electrical conductor 204 is electrically connected to the first partial electrical conductor 202 by soldering, brazing or screwing.
electrical assembly. 13. The method according to any one of claims 1 to 12,
The heat sink 704 includes at least one cavity 708 , wherein the electrical circuit is located at the bottom of the cavity 708 .
electrical assembly. 14. The method of claim 13,
The cavity 708 is at least partially filled with an electrical insulator, gel 950 or an epoxy resin to at least partially cover the electrical circuit.
electrical assembly. 15. A voltage converter comprising the electrical assembly of any one of claims 1 to 14, comprising:
The voltage converter further includes a component 702 , wherein the fire protection element 404 is at least one flexible blade configured to be deformed by the component 702 to press the electrical circuit against the heat sink 704 . having (406)
voltage converter.

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