A magnetic core device and a power converter

Abstract

The present invention relates to a power converter comprising a housing in which is mounted a conductive assembly including a busbar, the housing locally forming a cavity in which is housed at least partially a magnetic core device, the magnetic core device at least partially surrounding the busbar within the cavity, the cavity containing a resin immersing a portion of the magnetic core device. Figure for the abstract: Fig. 2

Description

Title of the invention: A magnetic core device and a power converter

[0001] The present invention relates to a magnetic core device and a power converter.

[0002] Power converters of an electric or hybrid electric vehicle are designed to convert an input voltage into an output voltage intended to power the electric drive or other electrical equipment of the vehicle.

[0003] As is known, an electric or hybrid electric vehicle comprises an electric drive consisting of an electric motor and an inverter that converts a direct voltage (DC) into an alternating voltage (AC) in order to drive the electric motor. In addition to the inverter, the electric or hybrid electric vehicle comprises other power converters such as an on-board charger connected to an alternating current grid and thus charging the electricity into a battery of the vehicle, or a DC / DC converter.

[0004] A power converter includes one or more magnetic core devices that are housed in a mounted housing of the power converter and are secured to said housing. The magnetic core devices may be used to prevent or limit undesirable effects such as electromagnetic interference (EMI) from the elements of the power converter.

[0005] Although the magnetic core is fixed to the inner surface of the housing, in the case of heavy magnetic cores, especially for high voltage inverters (above 400V), when the power converter is subjected to vibration, uncontrolled impact and / or unexpected high temperature, fixing by glue or nuts alone cannot ensure that the magnetic core is always correctly fixed at its own predetermined position. A displacement of the magnetic core would result in a decrease in performance or even malfunction of the magnetic core device and / or the entire power converter, and potentially mechanical breakage.

[0006] Therefore, the main objective of the present invention is to provide a fixing mechanism which can improve the robustness of the magnetic core device and the power converter while reducing the manufacturing cost.

[0007] The present invention relates to a power converter comprising a housing in which is mounted a conductive assembly comprising a set of bus bars, the housing locally forming a cavity in which is housed at least partially a magnetic core device, the magnetic core device surrounding at least at least partially the busbar in the cavity, the cavity containing a resin immersing a portion of the magnetic core device.

[0008] The power converter according to the invention may be an inverter that converts a direct voltage into an alternating voltage in order to drive an electric motor of an electric drive of an electric vehicle or a hybrid electric vehicle. The alternating voltage may be a polyphase alternating voltage, in particular a three-phase alternating voltage. Alternatively, the power converter may be an on-board charger or a DC / DC converter of the electric vehicle or the hybrid electric vehicle.

[0009] The resin allows the magnetic core device to be held in position in the housing despite vibrations.

[0010] The resin contained in the cavity advantageously surrounds the magnetic core device.

[0011] A resin height in the cavity in a direction transverse to a bottom of the cavity is at least 30% of the height of the core device in said direction.

[0012] Such a height is a valid compromise between the additional weight linked to the addition of resin and maintaining the position of the magnetic core device in the cavity.

[0013] The resin advantageously immerses at least a portion of the part of the busbar surrounded by the magnetic core device.

[0014] Such immersion in the resin allows the bus bars to be held in the cavity as well as good thermal evacuation of the calories in the bus bars.

[0015] The resin immerses at least 30% of the portion of the busbar surrounded by the magnetic core device, and advantageously at least 50%.

[0016] The housing advantageously comprises a set of pipes intended to receive a liquid for cooling the heat generated in the housing and arranged to evacuate the heat generated in the housing to at least one of the pipes running along the magnetic core device.

[0017] Such a cooling system makes it possible to combine the advantage of the evacuation of calories by the resin with the benefit of then having the proximity of the resin to the cooling circuit, to evacuate the calories from the resin more efficiently.

[0018] The resin has a thermal conductivity of between 1 and 4 W / mK, for good heat dissipation.

[0019] Another aspect of the invention is an electric drive comprising an electric motor and the inverter as described above, configured to convert a direct voltage into an alternating voltage, in order to drive the electric motor.

[0020] Another aspect of the invention is an electric vehicle or a hybrid electric vehicle, comprising the electric drive configured to drive the electric vehicle or a hybrid electric vehicle.

[0021] Although the embodiments have been described with reference to a number of illustrative embodiments, it should be understood that other modifications and embodiments may be derived by those skilled in the art which will fall within the principles of this disclosure.

[0022] These and other objects, features, aspects and advantages of the present invention will become apparent to those skilled in the art from the following detailed description which, taken in conjunction with the accompanying drawings, discloses preferred embodiments of the present invention.

[0023] The invention will be better understood on reading the following description, and with reference to the appended drawings given as non-limiting examples, in which identical references are given to similar objects and in which:

[0024] [Fig.l] illustrates a power converter according to one embodiment of the present invention;

[0025] Figures 2 and 3 illustrate a magnetic core device of the power converter, the magnetic core device being partially immersed in resin;

[0026] [Fig.4] illustrates the cooling circuit of the power converter.

[0027] Several embodiments of the present invention will be detailed below with reference to the drawings. It will be obvious to those skilled in the art that the following description of these embodiments of the present invention is provided for the purpose of illustration only and not for the purpose of limiting the invention as defined by the appended claims and their equivalents.

[0028] The invention relates to an electric vehicle or a hybrid electric vehicle comprising wheels and an electric drive configured to drive, at least indirectly, at least one of the wheels of the vehicle. The electric drive comprises an electric motor and an inverter as a power converter, the inverter being configured to drive the electric motor by means of an alternating voltage generated by the inverter. The power converter may alternatively be an on-board charger or a DC / DC converter of the electric vehicle or the hybrid electric vehicle.

[0029] [Fig.l] illustrates a power converter 100 according to one embodiment of the present invention. The power converter 100 may be, as mentioned above, an inverter configured to convert a direct voltage into an alternating voltage in order to drive the electric motor. The alternating voltage may be a multi-phase alternating voltage, in particular a three-phase alternating voltage.

[0030] The power converter 100 comprises a housing 110, a magnetic core device 1, and an electronic board mounted on a bottom plate of the housing 110. The housing 110 is preferably made of a conductive material (e.g., such as AlSil2(fe)) and may be manufactured by a die-casting process. The electronic board is preferably a printed circuit board (PCB). A direct current conductor assembly 120 includes a set of bus bars 121 (i.e., positive and negative terminals). The bus bars 121 are preferably in the form of plates.

[0031] In the remainder of the description, the converter housing has the X axis illustrated in [Fig.l], that is to say that the X axis is perpendicular to a bottom of the housing, the “height” will therefore be defined according to the direction of the X axis and the term “transverse face” will designate the surfaces containing the X axis.

[0032] The housing 110 comprises a top cover, the bottom plate, side walls and a main chamber defined by the bottom plate and the side walls. The main chamber is used to house the electronic card and the magnetic core device(s) 1 of the power converter 100. Other elements of the power converter 100, such as a card supporting other electronic components used or not for EMC filtering (may also include current measuring elements), a heat sink and certain electronic components, may also be housed in the main chamber.

[0033] The housing 110 also comprises at least one inner wall defining a cavity 111 in the main chamber. As illustrated in [Fig.2], the inner wall comprises two portions: a first portion 110a extends for example from a side wall of the housing forming a bottom for the cavity substantially parallel to the lower plate and a second portion 110b which extends continuously from the first portion 110a forms a side wall of the cavity 111 substantially parallel to the side wall of the housing from which it extends.

[0034] The volume of the open cavity 111 is therefore defined by a portion of the side wall of the housing, and the inner wall 110a, 110b, which extends from this side wall. The volume of the cavity is finally defined by longitudinal walls upstream and downstream of the magnetic core device.

[0035] The magnetic core device 1 comprises a body 51 comprising a magnetic core 3, the body being housed in the cavity 111. The device 1 also comprises at least one fixing lug 7 of the body to the housing 110.

[0036] The body 51 advantageously has a shape complementary to that of the cavity 111. The body illustrated in [Fig. 2] advantageously comprises two opposite side walls 55c and 55d which are respectively opposite the side walls of the cavity. The body comprises a lower part 54 opposite the bottom of the cavity and an upper part 53 opposite the lower part. In the illustrated embodiment, the height of the side walls of the cavity is of the order of the height of the side walls of the body 51.

[0037] Figures 2 and 3 illustrate a cross-section of the magnetic core device 1 housed in the cavity.

[0038] In [Fig.2], a resin poured into the cavity 111 surrounds the body 51 so that the lower part and at least a part of the side walls 55c and 55d are in contact with the resin.

[0039] Advantageously the resin height in the cavity is at least 30 percent of the height of the core device.

[0040] The resin has a thermal conductivity ranging from 1 to 3-4W / mK, such as epoxy or other silicone-based resin, allowing the temperature of the bus bars to be reduced, the body not heating up. The resin, once polymerized, also has mechanical properties of hardness, participating in the fixing of the core device as well as in the vibration damping of the immersed materials, which are the body and the bus bars.

[0041] The magnetic core 3, acting as an inductor to filter common mode or differential mode currents or a combination of both, is used to prevent or limit undesirable effects such as electromagnetic interference or even physical damage to the elements of the power converter 100.

[0042] The magnetic core device 1 comprises at least one passage 61 configured to allow the passage of at least one electrical conductor (for example the bus bars 121). The passage 61 is a passage comprising two openings 61a located respectively at each of the two opposite side walls 55a, 55b of the body 51, the two openings 61a being opposite each other. The bus bars 121 can thus pass through the magnetic core device 1, via the openings 61a and the passages 61 of the magnetic core device 1. The passage 61 preferably has a shape complementary to the shape of the extrinsic element 121.

[0043] The magnetic core device 1 may further comprise at least one insulating layer 58 made of an insulating material, such as plastic. The at least one insulating layer 58 is configured to separate the magnetic core 3 and the at least one electrical conductor 121 which passes through the magnetic core 3 from the body 51. Alternatively, the body is intrinsically insulating, without a specific insulating layer.

[0044] The passage 61 comprises two side walls substantially parallel to the side walls 55c and 55d of the body, the two walls of the passage being advantageously separated by a minimum clearance of 1 to 2 mm to allow the passage of the bar 121.

[0045] The magnetic core 3 is either a single piece or consists of several parts made respectively of a magnetic material which is, for example, a nanocrystalline material, a ferrite material and an iron powder material, or any combination of these materials. Alternatively, the magnetic core 3 may be made of magnetic materials different from those mentioned above.

[0046] Alternatively, the body 51 (illustrated in FIGS. 2 to 4) of the magnetic core device 1 is the magnetic core 3. In this case, the magnetic core 3 is preferably made of an iron powder material, such as sintered ferrite. The side walls 55a to 55d of the body 51 are side walls of the magnetic core 3. The openings 61a and the passage(s) 61 of the magnetic core device 1 are openings and passages formed on / in the magnetic core 3.

[0047] Beyond the body, the lateral distance between the bus bar 121 and the cavity 111 must be greater than or equal to the minimum electrical insulation distance between conductors in air and the lateral distance between two bus bars on the surface of the resination must be greater than or equal to the minimum insulation distance between adjacent conductors along the insulating surface on which they are mounted. For example, the lateral distance between the bus bar 121 and the cavity 111 and between two bus bars must be greater than or equal to 5 mm and advantageously greater than 10 mm in the case of our product geometries.

[0048] In an embodiment illustrated in [Fig. 3], the resin infiltrates into the passage of the magnetic core and at least partially immerses the portion of the bus bars 121 passing through the passage. The resin immerses at least 10% of this portion of the bus bars. The resin immerses at least 30% and advantageously at least 50% of this portion of the bus bars. The bar 121 is thus held in the passage and the resin makes it possible to effectively evacuate the calories from the bus bar 121.

[0049] As illustrated in [Fig.4], a pipe assembly 122 advantageously extends close to the magnetic core device 1. The pipe assembly is directly formed by one or more walls of the housing by through or non-through recesses and / or clearances provided in one or more walls extending towards the inside or the outside of the housing.

[0050] The set of pipes forms, for example, a parallel circuit with two branches between a single inlet and a single outlet, making it possible to improve the evacuation of the heat generated in the housing.

Claims

Claims

1. A power converter (100) comprising a housing (110) in which is mounted a conductor assembly (120) comprising a busbar set (121), the housing locally forming a cavity (111) in which is at least partially housed a magnetic core device (1), the magnetic core device (1) at least partially surrounding the busbar set in the cavity (111), the cavity (111) containing a resin immersing a portion of the magnetic core device.

2. A converter according to claim 1 wherein the resin contained in the cavity (111) surrounds the magnetic core device.

3. Converter according to claim 2 wherein a resin height in the cavity (111) in a direction transverse to a bottom of the cavity is at least 30% of the height of the core device (1) in said direction.

4. A converter according to any preceding claim wherein the resin immerses at least a portion of the part of the busbar (121) surrounded by the magnetic core device.

5. Converter according to claim 4 in which the resin immerses at least 30% of the part of the busbar surrounded by the magnetic core device, and advantageously at least 50%.

6. Converter according to any one of the preceding claims in which the housing (11) comprises a set of pipes (122) intended to receive a liquid for cooling the heat generated in the housing (110) and arranged to evacuate the heat generated in the housing (110) at least one of the pipes running along the magnetic core device.

7. A converter according to any preceding claim wherein the resin has a thermal conductivity of between 1 and 4 W / mK

8. An electrical energy converter according to any preceding claim, being an inverter for transforming the DC input electrical signal into an AC output electrical signal.

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