AC-DC CONVERTER

AC-DC converter

A AC-DC converter to be integrated in a rotating electrical machine.

The electronics power replaced nowadays the electro-mechanical means formerly for power supply and control of modern rotating electrical machines.

Either rotating electrical machines single phase or polyphase, synchronous or asynchronous, operable as a motor or as a generator, one or more electronic modules power control currents and voltages applied.

A current equipment of a motor vehicle is constructed by a reversible rotary electric machine, i.e. which is adapted to operate as a generator and charge a battery when it is coupled to the thermal engine of the vehicle, and to operate as a motor for starting, or providing additional mechanical power, when it is powered by the vehicle electrical system.

The machine, said " [...] -starter" has the most often:

-a rotor including permanent magnets and/or an inductor for bringing an excitation current;

-a stator including phase windings in which currents phase.

The application FR2886506 company EQUIPEMENTS VALEO ELECTRIQUES ENGINE described extremely detailed mechanotronics of a three-phase [...] starter comprising:

-a driving module constituting a brush holder regulator controlling the excitation current;

-three power modules of an inverter-continuous generating the phase currents in the motor mode or rectifying the phase currents in alternator mode;

-a control module of the driving module and power modules;

-a cooling device, generally comprised of a heat sink including a hydraulic circuit for cooling.

The power modules are in the form of a housing, by a phase, with externally of connecting elements and are arranged on the back porch of the [...] -starter. These modules are secured to the cooling device to allow heat transfer between said power modules into the cooling circuit, for the purpose of heat dissipation generated by the power modules.

To control these power modules, a control board is connected to the outer elements connect modules. The control board, generally positioned above the power modules to facilitate the connection, is therefore remote from the cooling system on which the power modules are attached. However, the control board generates a heat dissipate that it is necessary to prevent damage to the components on said control board.

Constraints space and component placement limit the possible placement of the card control of the assembly. Therefore, it is not possible to place the probe card in the vicinity of the cooling device. Therefore, it is necessary to establish means for cooling the probe card, while taking into account the space allocated to components on the AC-DC converter.

The present invention aims at providing an attachment means for attaching the various components of an AC-DC converter, while performing a thermal transfer function of the control board to the cooling device for the aforesaid problem.

To this end, the present invention relates to a AC-DC converter to be integrated in a rotating electrical machine, -comprising at least one power module, a control module for controlling the at least one power module, a cooling device, wherein the at least one power module is attached to the cooling device via at least one fastening means, and the control module is based on the at least one fastening means so as to transfer heat generated by at least a portion of the control module to the cooling device.

Advantageously, the use of fastening means for fastening the power modules to the cooling device, and thermally bonding between the probe card and said cooling device via a contact surface between said fastening means and the probe card, can efficiently dissipate heat present on the test card without the need for other cooling device, thereby reducing the size of the cooling device and so the entire AC-DC converter.

Furthermore, the sizing means can be used for does not interfere with the components on the probe card.

The AC-DC converter to be incorporated with a rotary electric machine according to the invention may also include one or more of the characteristics below, considered individually or in all technically possible combinations:

The attachment means is made of a material having mechanical strength higher than 400 MPa and a coefficient of thermal conductivity greater than 100 W/mK; and/or

-The control module is based on a flat contact surface of the fastening means, said planar surface being substantially parallel to the mean plane of the control module; and/or

-The contact surface of the fastening means is greater than or equal to that of the component (s) of the control module to be cooled; and/or

AC-DC-The converter of the present invention comprises from the fastening means and the control module a thermal glu; and/or

-The attachment means is made of aluminium 7075-T6; and/or

-The fastening means is a screw has a thread and a screw head, the thread for attachment of the power module with the cooling device and the control module based on the screw head; and/or

-The screw head is hexagonal in shape.

The invention also relates to a rotating electric machine comprising a AC-DC converter according to the invention.

The invention will be more preferably to the light of the following description which is given only as indicative and which is not intended to limit the invention, the accompanying Figures below:

_AOE280A2AO> Figure 1 is a isometric life of the AC-DC converter according to the prior art;

_AOE280A2AO> Figure 2 represents one embodiment of a AC-DC converter according to the invention;

_AOE280A2AO> Figure 3a and 3b is respectively two embodiments of fastening means according to the invention;

_AOE280A2AO> Figure 4 is a sectional view of a securing means of the invention interact with the various elements of the AC-DC converter.

Figure 1 represents a AC-DC converter 100 for an electrical machine according to the prior art. The AC-DC converter 100 comprises a cooling device 14, power modules 12 disposed above said cooling device 14 and a control card 16. The probe card 16 is attached to the cooling device 14 through the screws 20, arranged on the circumference of the probe card 16. The power modules 12 are also secured to the cooling device 14 by means of screws 22 placed on either one of the power modules 12. An example power module 12 is described in British Patent FR1361971.

The probe card 16 includes components 18 for inter alia control the power modules 12. These components 18, however, generates heat during operation of the AC-DC converter 100. The AC-DC converter 100 as set forth in Figure 1 does not have means for cooling the probe card 16. However, it is necessary to dissipate heat present in these components to avoid reducing their lifetime, or interfere with their proper operation.

The the present invention proposes to replace at least some of the screws 22 for fixing the power modules 12 with the cooling device 14, by special screws 23 as shown in Figure 2.

Figure 2 represents a AC-DC converter 100 according to an embodiment of the invention. The AC-DC converter 100 comprises a cooling device 14, power modules 12 disposed above said cooling device 14 and a control card 16 (not shown in Figure 2). The probe card 16 is attached to the cooling device 14 through the screws 20, arranged on the circumference of the probe card 16. The power modules 12 are also secured to the cooling device 14 by means of screws 22 on the one hand and via screws 23 placed diagonally screws 22 on a same power module 12.

These special screws 23 are composed of a thread 24 and a screw head 25, which may be hexagonal in shape as shown in Figure 3a, or cylindrical as shown in Figure 3 b.

The surface 26 above the screw head 25 is flat in shape, so that once the special screws 23 placed and screwed, the surface 26 is substantially parallel to the mean plane of the probe card 16 positioned above, as shown in Figure 4. Therefore, the planar surface 26 of the special screw 23 is in contact with the back surface of the probe card 16.

The arrangement shown in Figure 4, using the special screws 23 for fixing the power modules 12 with the cooling module 14, transferring heat from the heating components 18 on the surface of the probe card 16 to the cooling system 14, via the special screws 23. The heat dissipated components 18 then follows a path represented by the arrows 40 in Figure 4.

Furthermore, the surface 26 of the screw head of the special screw 25 23 is generally above the surface of the components 18 present on the test card 16, to ensure that heat dissipated by said components 18 is completely transferred to the special screws 23 and allow diffusion of the heat present on the test card 16.

The use of these special screws 23 thereby perform a cooling function on the test card 16, without changing the design of the cooling device 14. Furthermore, the special screws 23 do not interfere with the placement of the power modules 12 or 18 with the components of the probe card 16.

Glu thermal A 30 can be placed between the rear surface of the probe card 16 and the surface 26 of the screw head 25, to facilitate heat transfer between the two surface. Furthermore, the use of a thermal glu 30 can provide additional fixation on the center of the probe card 16 and thereby limit the vibrations generated by the operation of the AC-DC converter 100 within a rotating electric machine.

Upon fastening of the special screw 23, the power module 12 is held together with the cooling device 14. A washer 32, for example steel, is disposed between a planar surface of the screw and the power module 12 to distribute the tightening torque of the screw to prevent damage to the power module 12 during the screwing.

In order to ensure the fastening function in the best conditions, the special screw 23 is to be made of a material with a high mechanical strength, generally greater than 400 MPa. Furthermore, the special screw 23 serving as a heat spreader, it is preferable that the material has a coefficient of thermal conductivity suitable for its function. A coefficient of thermal conductivity of the order of 100 W/mK can properly perform the function of thermal diffusion of the components 18 on the test card 16 to the cooling device 14.

Selected materials available operable to perform the special screws 23 according to the embodiments presented in Figure 2,3a, 3b and 4, the Aluminium 7075-T6 is particularly advantageous in terms of mechanical strength and thermal diffusion for making special screws 23.

The invention has been described above with the aid of embodiments presented in Figures, without limiting the general inventive concept.

Numerous other modifications and variation suggest themselves to those skilled in the art, after reflection on the various embodiments shown in this application. These embodiments are example and are not intended to limit the scope of the invention, which is determined exclusively by the claims below.

Any references used in the claims is not to be interpreted as limiting the scope of the invention.