INVERTER WITH A DEVICE FOR MUTUAL ALIGNMENT OF THREE COMPONENTS

Description

[0001] The present invention claims priority from French application 2112148 filed on November 17, 2021.

[0002] The present invention relates to the field of assemblies comprising an electronic card interfacing with at least two other elements, and in particular the field of inverters, such as inverters adapted to control the operation of an electric traction machine of an electric or hybrid vehicle.

[0003] In the field of power electronics, an inverter is a voltage converter used to generate alternating voltages and currents from an electrical energy source of different voltage or frequency. In particular, an inverter can generate alternating voltages suitable for the operation of an electric motor, whether synchronous or asynchronous, from a direct voltage source, such as an electric battery.

[0004] A polyphase inverter, for example three-phase, allows a direct voltage to be chopped into a balanced polyphase (for example three-phase) sinusoidal voltage.

[0005] To achieve this, inverters include power modules with electronic switches, for example IGBTs (IGBT stands for insulated gate bipolar transistor), whose opening and closing are controlled appropriately.

[0006] Such an inverter thus comprises an assembly of several components: electronic cards (control card and power card), a certain number of power modules, electrical connections in the form of interconnection bars (generally referred to by the English term "busbars") generally assembled into a busbar system, and where appropriate sensors, in particular current sensors. In this document, a "busbar system" corresponds to a component comprising one or more busbars.

[0007] These elements are usually enclosed in a protective casing also called a housing.

[0008] The various components mentioned above are thus in mechanical and / or electronic interface with each other in a relatively complex configuration.

[0009] Each power module is thus connected on the one hand to the busbar system, and on the other hand to the driver board, via pins soldered to it.

[0010] The current sensors are connected to the control board and operate by Hall effect. Each sensor must be precisely positioned in the opening of a ferromagnetic C-shaped element positioned around a busbar in order to measure the current in that busbar.

[0011] Mounting an inverter is therefore complex and requires taking measures to ensure the correct positioning and orientation of the components in relation to each other.

[0012] In order to simplify the configuration of the inverter, to limit the quantity of parts and in particular screws to be used, and to gain compactness, it is possible to combine the functions of the control card and the driver card into a single electronic card, that is to say on a single PCB (from the English "Printed Circuit Board" which is generally translated into French as "printed circuit"). The use of a single electronic card instead of two, however, makes the positioning of the different components of the inverter even more complex. Indeed, for example, a very precise relative positioning between the electronic card and the control pins of the power modules on the one hand, and a very precise relative positioning between the electronic card (which carries the current sensors) and the busbars on the other hand, are simultaneously necessary.

[0013] There are some general solutions in the state of the art that have been developed to improve the relative positioning between electronic components.

[0014] For example, document EP3177123 proposes mounting an electronic card on which numerous components are to be soldered on an electronic card support which is provided with guide holes. The guide holes make it possible to correct, to a certain extent, the orientation of the male contacts (pins) which are to pass through the electronic card and be soldered there.

[0015] This solution is however imperfect in that it is complex, in that although it corrects the orientation of the male contacts where necessary, it does not guarantee exact relative positioning of the components with respect to the card, and finally in that the position obtained is hyperstatic, which must be avoided as far as possible.

[0016] An inverter according to the state of the art is disclosed in document EP2736160A1.

[0017] The present invention aims to optimize the relative positioning of the components of an inverter, by solving all or part of the problems indicated above.

[0018] Thus, the invention relates to an inverter comprising: an electronic card comprising a printed circuit; a power module comprising male connectors inserted into female connectors of the electronic card; a connector guide configured to maintain a given orientation between the male connectors; a busbar system, linked to the power module and comprising a ferromagnetic element adapted to cooperate with a current sensor; and said current sensor, which is rigidly linked to the electronic card.

[0019] The inverter comprises two elongated centering elements extending parallel and arranged at a distance from each other, and rigidly connected to a reference part of the inverter.

[0020] The two elongated centering elements pass through calibrated holes in the electronic card, the connector guide, and the busbar system.

[0021] The inverter further comprising a casing, the casing or part of the casing forms the reference part.

[0022] This ensures the desired alignment between the circuit board, connector guide, and busbar system.

[0023] The alignment of the three components, namely the electronic board, the connector guide (and therefore the connectors it guides), and the busbar system, is thus achieved simply, using two elongated centering elements. This allows the use of a single electronic board combining the functions commonly distributed between a control board and a driver board, while ensuring its correct alignment with two other components, namely the busbar system and the connector guide. The inverter can therefore, for example, have only one electronic board.

[0024] Alignment refers specifically to the centering and rotational retention of components relative to each other. The two elongated, parallel, and spaced-apart centering elements perform this alignment function isostatically.

[0025] By "calibrated" orifice is meant an orifice configured, in its shape and dimensions, to receive the pin which is advantageously mounted tightly in the orifice. The chain of dimensions between the elongated centering elements and the parts interfacing with the elongated centering elements allows in particular precise positioning of the parts with respect to the elongated centering elements, and therefore of the parts between them.

[0026] By using the housing as a reference part, the elongated centering elements allow, in addition to the relative alignment between the electronic board, the busbar system and the connector guide, to ensure correct positioning of these elements in the inverter housing. Other positioning means in the housing are therefore not necessary.

[0027] According to a configuration disclosed here, which is not the subject of the present invention, the two elongated centering elements are rigidly connected to one of the components among the electronic card, the connector guide, and the busbar system, the component to which the elongated centering elements are connected then forming said reference part, and the two elongated centering elements pass through calibrated orifices the other two components among the electronic card, the connector guide, and the busbar system.

[0028] The casing may have an inner wall forming at least one housing, suitable for receiving at least one power module so as to pre-position it in the inverter during its assembly.

[0029] The elongated centering elements can be pins.

[0030] Pins are elongated, rectilinear, prismatic or cylindrical elements.

[0031] The elongated centering elements may be centering fingers formed integrally with the housing.

[0032] The centering fingers (which can also be called indexing fingers) formed by the casing can have various sections to ensure their centering function: circular, cross-shaped, etc. The centering fingers can be of constant section and thus have a cylindrical or prismatic shape, or be slightly variable (for example, the centering fingers can be conical).

[0033] The inverter generally has several power modules, advantageously three power modules.

[0034] This is the classic architecture of an inverter allowing the production of a three-phase sinusoidal current, for example allowing the power supply of an electric traction machine of a motor vehicle.

[0035] The connector guide may include passages into which the male connectors of the power modules are inserted in order to hold them in the desired orientation.

[0036] The ferromagnetic element can be an open-section core, for example C-shaped, and the current sensor is positioned in an air gap of the core. This is a classic configuration of a Hall effect sensor, which requires precise positioning of the sensor in the air gap of the ferromagnetic element.

[0037] The inverter may further comprise a screen interposed between the power module(s) and the electronic card, said screen comprising calibrated orifices through which the two elongated centering elements pass.

[0038] The elongated centering elements then also allow the screen to be aligned with the other components of the inverter.

[0039] The male connectors may be pins (generally called "pins" according to English terminology) and the female connectors may be receiving holes formed in the electronic card and allowing the soldering of the pins. The busbar system may comprise one or more interconnection bars partly included in an overmolding made of plastic material, said ferromagnetic element being included in the overmolding. This configuration allows simple mounting of the inverter and a high level of integration, and is made possible thanks to the very good relative positioning between the components of the inverter that the invention offers.

[0040] The invention also relates to a method of assembling an inverter, said method comprising the steps of: providing a casing comprising two elongated centering elements extending parallel and arranged at a distance from each other, and rigidly connected to said casing; mounting a busbar assembly, the two elongated centering elements passing through two calibrated orifices in said busbar assembly, and fixing the busbar assembly to the casing; installing power modules in the casing, said power modules comprising male connectors; mounting a connector guide around said male connectors to maintain a given orientation between them; said two elongated centering elements passing through calibrated orifices in said connector guide;mounting an electronic card, the two elongated centering elements passing through calibrated orifices of said electronic card, which aligns said electronic card with respect to the connector guide and with respect to the busbar assembly, so that the male connectors of the power modules are received in corresponding female connectors of the electronic card and so that current sensors rigidly linked to the electronic card are positioned in an air gap of a ferromagnetic element of the busbar system. ;

[0041] Other features and advantages of the invention will become apparent in the description below.

[0042] In the attached drawings, given as non-limiting examples: there figure 1 represents, in a partial three-dimensional view, an inverter according to an embodiment of the invention; the figure 2 represents, according to a partial sectional view, the inverter of the figure 1 ; there figure 3 shows, in a three-dimensional sectional view, an aspect of the present invention; figure 4 shows, in a three-dimensional sectional view, another aspect of the present invention; figures 5 à 9 represent, according to partial three-dimensional views, different stages of the assembly of the inverter of the figure 1 , there figure 10 represents, according to a partial three-dimensional schematic view, an inverter housing which can be implemented in another embodiment of the invention.

[0043] There figure 1 represents, in a partial three-dimensional view, an inverter according to an embodiment of the invention. The inverter represented is an inverter suitable for powering and controlling an electric traction machine of a motor vehicle.

[0044] The inverter 1 comprises a casing 2, adapted to receive the various components of the inverter 1. The casing 2 is advantageously made of aluminum alloy, but can be formed of any other suitable material: steel, plastic, composite plastic material, etc.

[0045] To the figure 1 , only a lower part of the casing 2 is shown. Once the internal components of the inverter are assembled, the casing is closed by an upper part forming a cover, not shown, in order to ensure the protection of the components.

[0046] The inverter comprises an electronic card 3. The electronic card 3 combines the control and piloting functions of the inverter 1. The electronic card 3 comprises or consists of a printed circuit to which various electronic components and one or more microprocessors or microcontrollers are linked.

[0047] The electronic card allows in particular the control of the 4 power modules of the inverter (not visible in the figure 1 because placed under the electronic card 3, but visible in particular to the figures 6 And 7 described below). Each power module comprises male connectors 5, in the form of pins, which are soldered to the electronic card 4. The male connectors 5 pass through the electronic card 3 via holes adapted to receive said male connectors and are soldered there.

[0048] The inverter further comprises a busbar assembly 6. The busbar assembly comprises three interconnection bars 7 (or busbars), which are enclosed in a plastic overmold 8.

[0049] Each interconnection bar 7 is connected at one of its ends to a power module. This connection can be made by welding or screwing. Its other end, which protrudes from the casing 2, is intended to be connected to the electrical machine powered by the inverter, via another interconnection bar or a flexible conductive connection.

[0050] Each interconnection bar 7 is equipped with a ferromagnetic element allowing the measurement of the current flowing in said interconnection bar using a current sensor 9 carried by the electronic card 3. Three current sensors 9 are thus provided in the embodiment shown in figure 1 .

[0051] Each current sensor must be positioned precisely relative to the ferromagnetic element equipping the corresponding interconnection bar, as explained in more detail below with reference to the figure 3 .

[0052] Furthermore, all male connectors must be perfectly positioned with respect to the female connectors on the electronic board when assembling the inverter. This correct positioning is all the more complex since during assembly the power modules are not visible (because they are under the electronic board) and there are many male connectors to align simultaneously: in the example shown, there are seven male connectors 5 per power module, or twenty-one male connectors in total to align with the electronic board 3. A connector guide 10 (visible at figures 4 And 7 ) allows the orientation of the male connectors 5 to be maintained with respect to each other, but it is also necessary to ensure alignment with respect to the electronic card 3.

[0053] The present invention proposes to ensure alignment between the electronic card and the male connectors of the power modules on the one hand, and between the electronic card and the busbar assembly on the other hand, using a simple alignment system based on two elongated centering elements. In the example of the embodiment illustrated in figures 1 à 9 , the two elongated centering elements are two pins 11.

[0054] The pins 11 are elongated straight elements, advantageously cylindrical, parallel to each other and at a distance from each other. Their end can be beveled or rounded to facilitate the insertion of the components to be aligned.

[0055] There figure 2 shows in more detail, in a sectional view, the arrangement of the pins 11 in the inverter 1.

[0056] The two pins 11 are connected to the casing 2. More precisely, the pins 11 are inserted into wells 12 formed in the casing 2, by force or with very little play. The casing 2 thus forms a reference part with respect to which the alignment of the inverter components is carried out.

[0057] Each pin 11 passes through the busbar assembly 6, the connector guide 10, and the electronic board 3.

[0058] Each of these components has two calibrated holes for this purpose, made in the component with small position and dimensional tolerances.

[0059] The relative alignment of the three aforementioned components is thus very precisely obtained. Furthermore, this alignment is carried out isostatically: it is in fact possible to consider that one of the two pins 11 ensures the centering function (precise relative positioning, excluding relative orientation) while the other pin, thanks to its distance, ensures the orientation of the components.

[0060] In the example shown in the figure 2 , the inverter also comprises a screen 12, which is interposed between the power modules and the electronic card 3. The screen 12 can be metallic (for example steel or aluminum) and is held at a distance from the electronic card 3 by spacers 13. The alignment of the screen is also obtained using the two pins 11, as previously explained.

[0061] There figure 2 also allows the configuration of the current sensors 9 and the corresponding ferromagnetic elements 14 to be viewed. This configuration is also visible and more precisely at the figure 3 .

[0062] There figure 3 is a partial, sectional, three-dimensional view of the inverter 1. The section is made in the plane represented by the two pins 11. For greater readability, the pin 11, the current sensor 9 and the ferromagnetic element 14 shown in the figure 3 are not cut. The ferromagnetic element has a "C" configuration (so this type of ferromagnetic element is commonly referred to by the English expression "C-core").

[0063] Other configurations of ferromagnetic elements are possible. The ferromagnetic element can have various open sections providing an air gap, for example U-shaped or Ω (Omega).

[0064] The ferromagnetic element 14 thus comprises an opening, or air gap 15, in which the current sensor 9 must be positioned precisely.

[0065] The ferromagnetic element 14 surrounds an interconnection bar 7. It is advantageously included in the busbar assembly 6, for example by being integrated into the plastic overmolding 8.

[0066] There figure 3 thus illustrates the complexity of the very precise relative positioning which must be carried out between the current sensor 9 (and therefore the electronic card 3 to which it is connected) and the corresponding ferromagnetic element 14 (and therefore the busbar assembly to which it is integrated).

[0067] There figure 4 represents, according to another partial view, in section and in three dimensions of the inverter 1, the problem of the alignment of the male connectors 5 of the power modules. The section of the figure 4 is made in a plane parallel to the plane materialized by the two pins 11, and passing through the male connectors 5. Each power module in fact comprises several male connectors 5 intended for controlling the power module. These connectors can be in the form of pins, as in the example shown, and thus have a great length which makes their relative orientation quite uncertain. In order to guarantee the relative positioning and the relative orientation of the male connectors 5 between them, a connector guide 10 is used. The connector guide is a part, for example made of plastic, which has passages into which the male connectors of the power modules are introduced in order to maintain them in the desired given orientation.The passages may have a tapered portion, so as to allow for slight correction of the orientation and positioning of the pins relative to each other when placing the connector guide 10 around the pins.

[0068] The pins, or more generally the male connectors 5, must also be perfectly aligned with respect to the female connectors 16 of the electronic card 3. The female connectors 16 are, in the example shown, holes allowing the pins to pass through the electronic card 3 and to solder them there.

[0069] THE figures 5 à 9 present different stages of the assembly of the inverter of the figure 1 .

[0070] To the figure 5 , the lower part of the casing 2 is shown. The two pins 11 are assembled to the casing 2, ready to receive the stack of inverter components while ensuring their alignment.

[0071] The casing 2 shown here has the particularity of having housings 17, each housing 17 being intended to receive a power module.

[0072] In the first stage of assembly shown in figure 5 , the busbar assembly 6 is positioned in the casing 2. For this, the pins 11 are introduced into calibrated orifices of the busbar assembly 6, for example positioned on the lateral tabs 18 of the busbar assembly 6 formed by the plastic overmolding 8. Once aligned using the pins 11, the busbar assembly is fixed to the casing, for example by screws 19.

[0073] In the next step shown in the figure 6 , the three power modules of the inverter are reported in the housing.

[0074] A certain correspondence of shape between each housing 17 and a part of the power module placed therein allows a pre-positioning of the latter. Each power module 4 is thus pre-positioned in particular so that its output 20 is correctly positioned relative to the interconnection bar 7 to which it will be connected.

[0075] In the next step shown in the figure 7 , a connector guide 10 is placed on and around the male connectors 5. The connector guide is first placed in position on the pins 11.

[0076] For this, the pins 11 are introduced into calibrated orifices formed in the connector guide 10. The connector guide 10, the functional part of which is located in a plane distinct from that materialized by the pins 11, comprises two arms 21 in which the calibrated orifices intended to receive the pins 11 are formed.

[0077] Once the connector guide 10 is in position, which ensures the correct alignment of all the male connectors 5 of the power modules 4, it can be fixed to the casing (and / or where appropriate to the busbar assembly itself fixed to the casing), for example with screws 19.

[0078] The power modules can then be connected to the interconnection bars 7 and fixed in the housing 2 using flanges 22 (or other suitable fixing means).

[0079] There figure 8 represents the positioning of the screen 12 above the power modules. The screen 12 is aligned by inserting the pins 11 into calibrated holes therein. It should be noted, however, that the tolerances applied to these holes in the screen 12 may be greater than for the other components, since the alignment of the screen does not need to be as precise as the relative alignment of the busbar assembly, the connector guide and the electronic card. Spacers 23 are provided on the screen 12.

[0080] There figure 9 represents the step of mounting the electronic card 3 of the inverter. The electronic card 3 is aligned with the other components by inserting the two pins 11 into calibrated holes that it contains.

[0081] The electronic card is brought into contact with the spacers 23 which make it possible to maintain the desired distance between the electronic card 3 and the screen 12. The electronic card 3 is then fixed, for example by screws, to the casing 2. The fixing screws can pass through the spacers 23 and the screen 12 to be directly engaged in the casing 2.

[0082] When installing the electronic card 3, thanks to the guidance provided by the pins 11, the electronic card 3 is correctly aligned both with respect to the male connectors 5, since the connector guide 5 is indexed in position by the pins 11, and with respect to the air gap 15 of the ferromagnetic elements 14, since the busbar assembly 6 is also indexed in position by the pins 11.

[0083] This allows for correct and risk-free mounting of the card. It is indeed certain that the male connectors 5 penetrate precisely into the female connectors 16 of the card when it is put in place and lowered along the pins 11, in the casing 2. It is also certain that the current sensors are correctly positioned with respect to the ferromagnetic element 14, that is to say in its air gap 15 in the example shown.

[0084] All the inverter components are now assembled, and the housing 2 can be closed.

[0085] Although described with reference to a particular embodiment shown in the figures described above, the invention is obviously not limited to this single embodiment.

[0086] The embodiment shown in the figures described above uses the casing as a reference part to which the two pins 11 are fixed.

[0087] The embodiment shown has the advantage of not requiring any additional means to ensure the correct positioning of these three components in the inverter housing.

[0088] There figure 10 illustrates another embodiment of the present invention. More specifically, the figure 10 represents an inverter housing 2 which can be implemented in another embodiment of the invention.

[0089] Just like the casing 2 used in the embodiment shown in figures 1 à 9 , the casing 2 of the figure 10 is advantageously made of aluminum alloy, but may alternatively be formed of any other suitable material. In this case, only the lower part of the casing 2 is shown in the figure 10 .

[0090] This lower part includes a housing 17 adapted to receive and pre-position power modules, in this case three power modules in this example.

[0091] In this embodiment, the casing 2 forms the reference part with respect to which the alignment of the inverter components is carried out. However, instead of using attached pins, two centering fingers 24 are directly formed by the casing 2, i.e. they are integral with the casing.

[0092] The centering fingers 24 can in particular be machined from the mass of the casing. Just like the pins 11 of the embodiment described previously with reference to the figures 1 à 9 , the centering fingers 24 are elongated rigid elements, which are located at a distance from each other and which extend parallel to each other. They have a constant section, which gives them a generally cylindrical or prismatic shape. Their end can nevertheless be beveled or rounded to facilitate the insertion of the components to be aligned.

[0093] The formation of centering fingers directly from the material with the rest of the casing 2 has several advantages. The dimension chain for the alignment of the components is simplified, because a "link" in this chain is eliminated compared to the solution using inserted pins. This results in less dispersion and more precision. Alternatively, a slightly higher tolerance can be applied in the formation of the centering fingers while ensuring the desired alignment precision. In general, greater precision can be achieved because the centering fingers are integral with the casing. The machining of the centering fingers 24 and the machining of the rest of the casing 2 are carried out in the same reference frame.

[0094] Finally, this solution eliminates an assembly operation, since the centering elements, namely the centering fingers, do not have to be put in place during assembly because they are already present, formed by the casing.

[0095] The invention thus developed makes it possible to simply obtain correct alignment between three or more components of an inverter. This makes it possible to combine on a single electronic card functions that require precise physical positioning of the card with respect to other components of the inverter, generally managed by several cards. This also allows reliable and safe mounting of the card "blind", i.e. without being able to visually check, when mounting the card in the inverter, its correct alignment of the elements with which it interacts.

Claims

1. inverter containing: - a crankcase; - an electronic card (3); - a power module (4) containing male connectors (5) inserted into female connectors (16) of the electronic card (3); - a connector guide (10) configured to maintain a given orientation between male connectors (5); - a busbar system (6), linked to the power module (5) 4) and having a ferromagnetic element (14) suitable for co-operation with a current sensor (9); - said current sensor (9), which is rigidly linked to the electronic card (3), in which the inverter (1) has two elongated balance elements extending parallel and arranged remotely from each other, and rigidly linked to a reference part of the undulation their, and in which the two centering elements lengthen through calibrated orifices the electronic card (3), the connector guide (10), and the busbar system (6) so as to ensure a desired alignment between the electronic card (3), the connector guide (10), and the busbar system (6), characterized in that the case (2) or part of the case (2) forms the reference part.

2. inverter according to claim 1 in which the case (2) has an inner wall forming at least one housing, suitable for receiving at least one power module (4) so that it can be pre-positioned in the inverter when it is assembled.

3. inverter according to Claim 1 or Claim 2, in which elongated centering elements are pins (11).

4. inverter according to one of the previous claims, in which elongated centering elements are centering fingers formed monobloc with the crankcase (2).

5. inverter according to one of the previous claims with several power modules (4), advantageous three power modules (4).

6. inverter according to Claim 5, in which the connector guide (10) contains passages in which male connectors (5) of power modules (4) are introduced to maintain them according to the desired given orientation.

7. inverter according to one of the previous claims in which the ferromagnetic element (14) is an open section core, e.g. in C, and the current sensor (9) is positioned in a core spacer.

8. inverter according to one of the previous claims, which also includes a screen (12) between the power module(s) (4) and the electronic card (3), the said screen having calibrated holes through which the two elongated center elements cross.

9. inverter according to one of the previous claims, in which male connectors (5) are pins and female connectors (16) are receiving holes formed in the electronic card (3) and allowing the welding of pins.

10. inverter according to one of the previous claims in which the busbar system (6) has one or more interconnection bars (7) partially included in a plastic overcast (8), the said ferromagnetic element (14) being included in the overcast.

11. Assembly process of an inverter, the process consisting of the steps of: - supply of a case (2) with two elongated centering elements extending parallel and arranged remotely from each other, and rigidly linked to that case (2); - assembly of a busbar set, the two elongated centering elements crossing two calibrated orifices of the said busbar set, and fixation of the set of busbar on the crankcase (2); - installation of power modules (4) in the crankcase (2), said power modules (4) with male connectors (5); - installation of a connector guide (10) around the said male connectors (5) to maintain a given orientation between them; the two elongated centering elements passing through calibrated orifices of the said connector guide, - mounting of an electronic card (3), the two elongated centering elements straining calibrated orifices of the said electronic card (3), thus aligning the said electronic card (3) with the connector guide (10) and with the busbar set, male connectors (5) of power modules (4) are received in corresponding female connectors (16) of the electronic card (3) and so that current sensors rigidly linked to the electronic card (3) are positioned in a spacer of a ferromagnetic element (14) of the busbar system (6).