Title of the Invention: An Elastic Member for Electric Power Converter

Field of Invention

[0001] The present subject matter relates in general to an electrical power converter, and more specifically, relates to an improved fixation of a module in an electric power converter by means of an elastic member.

Background

[0002] An electric power converter is a power electronic device or circuitry that converts direct current (DC) to alternating current (AC), and/or vice versa. An electric power converter includes electronic components, such as, power semiconductors, capacitors, etc., configured to communicate electrically with an electrical machine. By virtue of the aforementioned electrical communication, the electric power converter may transfer control signals to the electrical machine thereby controlling said machine. During operation, the electric power converter is susceptible to overheating since the electronic components generate a lot of heat. To combat the heating problem, heat generated by the electronic components is dissipated by means of a heat sink in thermal contact with said components. However, scenarios exist where heat generated by the electric power converter is not effectively conducted to the heat sink from said components. In such scenarios, the electronic components of the electric power converter is susceptible to failure.

[0003] In one such scenario, the electronic component (a power semi-conductor, for instance, that generates heat during operation) is pressed onto the heat sink by a clip disposed between said component and heat sink, the clip merely clamping said component onto the heat sink. The clip is however an additional device which requires a separate assembly process. Moreover, such clips are susceptible to vibrations and may loosen on prolonged exposure to vibrational environments. i [0004] In another scenario, the electronic component (a power semi-conductor, for instance, that generates heat during operation) is pushed onto the heat sink by a spring plate. The spring plate is sandwiched between the electronic component and a second component of the electric power converter such that the second component presses the spring plate which further pushes the electronic component onto the heat sink. However, similar to the scenario explained in the previous paragraph, the spring plate is susceptible vibrations which may cause an undesired movement of the spring plate in the sandwiched position. This scenario is also disadvantageous because the spring plate is not integrally fixed to any component, and hence, may be unreliable on prolonged exposure to vibration. Moreover, existing spring plates are configured such that forces exerted on it are unevenly distributed, which in consequence, lead to failure of the spring plate over time. Accordingly, possibility of overheating is high for conventional electric power converters. Moreover, normal operation of the electrical machine, with which an electric power converter is electrically connected, is susceptible to failure. It is therefore imperative that the electric power converter is safeguarded from any heating issues, thereby also safeguarding the integrity of the electrical machine.

[0005] Therefore, the technical solution sought by the present subject matter is how to optimize fixture of electronic components onto the heat sink of an electric power converter, hence, improving efficiency of heat dissipation.

Summary of the Invention

[0006] The present subject matter seeks to solve the above-mentioned problem of conventional electric power converters. The present subject matter relates to an electric power converter comprising a housing; a module comprising at least one electronic component, wherein the at least one electronic component is in thermal contact with the housing; and a supporting element comprising an over-molded body, disposed in the housing, wherein an elastic member is partially over-molded in said body of the supporting element and exerts pressure on the module in a direction towards the housing and away from the supporting element. Accordingly, as the elastic member is partially over-molded into the supporting element, a dislocation of the elastic member within the electric power converter is eliminated. Further, the module pressed, or pushed, onto the housing and a reliable thermal contact is maintained.

[0007] According to one aspect, the elastic member comprises two flat plates, each of said plates interconnected by a connecting arm.

[0008] In an aspect, the arrangement of the connecting arm axially shifts the second flat plate form the first flat plate in a direction parallel to axis X-X', the axis X-X' defining a direction of assembly or dis-assembly of the electric power converter.

[0009] In an aspect, the connecting arm extends slantwise between one end of a first flat plate and one end of a second flat plate. Said aspect is of non-limiting nature, as the connecting arm may also be arranged, or oriented, to be parallel to axis X-X' and extending between the two flat plates.

[0010] In another aspect, the first flat plate of the elastic member is adapted to push the module away from the supporting element and towards a bottom cover of the housing.

[0011] In yet another aspect, the second plate of the two flat plates is over-molded in an electrical insulating material of the supporting element.

[0012] According to an example, the supporting element comprises an electrical conductive means over-molded in the electrical insulating material, the electrical conductive means adapted to carry and distribute electric power.

[0013] According to an example, the bottom cover of the housing is a heat sink adapted for dispersing heat generated by the at least one electronic component of the module. The bottom cover may therefore serve a dual purpose as an enclosure for components within a cavity of the housing, and as a heat sink for effective dissipation of heat to ambient environment. [0014] According to one aspect, a thermally conductive material is disposed between the module and the bottom cover to achieve said thermal contact.

[0015] According to one example, the at least one electronic component of the module is a power semi-conductor. The module can comprise command interface. The command interface permit to control the power semi-conductor. The module can comprise DC busbars. The DC busbars can supply with DC current the power semi-conductor. The module can comprise AC busbars. The AC busbars can supply with AC current stator windings. The module can comprise a closed space in which is located the power semi-conductor.

[0016] The present subject matter also relates to an assembly comprising: an electric machine; and an electric power converter in electric communication with the electric machine, wherein the electric power converter is configured in accordance with any of the preceding claims. As structural and operational integrity of the elastic member, configured in the above described manner, is ensured, the electric power converter, and hence, the assembly functions without failure.

[0017] In an aspect, the electric machine is a rotary electrical machine, an electric power source, an electric power storage, an electronic control unit, or a combination thereof.

Brief Description of Drawings

[0018] The features, aspects, and advantages of the present invention will be better understood with regard to the following description and accompanying figures. The description refers to the annexed drawings, wherein:

[0019] FIG. 1 illustrates an exploded view of an electric power converter, in accordance with the present subject matter;

[0020] FIG. 2 illustrates another perspective of the electric power converter, depicting fewer components, in accordance with the present subject matter; [0021] FIG. 3 illustrates a zoomed in view of a support element of the electric power converter, in accordance with the present subject matter;

[0022] FIG. 4 illustrates an assembled perspective of the electric power converter depicted in FIG. 3, configured in accordance with the present subject matter; and

[0023] FIG. 5 illustrates a cross-section view of the electric power converter, depicting an elastic member partially over-molded in the support element, in accordance with the present subject matter.

[0024] The figures are not necessarily to scale, and the size of some parts may be exaggerated to more clearly illustrate the example shown. Moreover, the drawings provide examples and/or examples consistent with the description, however, the description is not limited to the examples and/or examples provided in the drawings.

Detailed Description

[0025] The present subject matter relates in general to improving dissipation of heat from an electric power converter. Specifically, the present subject matter relates to improve thermal conductivity between a heat generating module and a housing of an electric power converter. An electric power converter, is normally used in conjunction with an electrical machine, such as, a rotary electrical machine, an electric power source, an electric power storage, an electronic control unit (ECU), or a combination thereof.

[0026] In the description that follows, reference is made to accompanying drawings, which form part thereof, and in which is shown by way of illustration specific implementation in which the invention maybe practiced. These implementations are described in sufficient detail to enable that skilling in the art to practice the invention, and it is to be understood that the implementations may be combined, or that other implementations may be utilized, and that structural and logical changes may be made without departing from the scope of the present invention. The following detailed description is, therefore, not to be taken in a limiting sense, and the scope of the present invention is defined by the appended claims and their equivalents.

[0027] FIG. 1 illustrates an electric power converter 100, according to the present subject matter. The electric power converter 100, in accordance with the present subject matter, includes a housing 102, a module 112 in thermal contact with the housing 100, and a supporting element 110 that enables the aforementioned thermal contact. The module 112, in the illustrated examples, is accommodated within the cavity 114 of the housing 102. The module 112 includes at least one electronic component, such as, a power semi-conductor. More than one such module 112 may be disposed within the housing 102. Moreover, as depicted in FIG. 1, the electric power converter 100 may also include a control module 106 disposed within the cavity 114 of the housing 102. The control module 106 is in the form of a circuit board, formed for instance, by a substrate, to which electronic components are secured and electrically connected together by electrical tracks. An electrical circuit is hence formed for generating one or more electrical signals that in turn make it possible to control the module 112. The substrate may be a printed circuit board (PCB) provided with the electrical tracks.

[0028] During normal operation, the at least one electronic component of the module 112 generates heat. To efficiently dissipate the heat generated, the module 112 is pressed onto the housing 102 by the supporting element 110 so that a thermal contact is established there between. Specifically, the supporting element 110 includes an elastic member 108 that presses, or exerts pressure, on the module 112. Therefore, heat generated by the module 112 may be conducted efficiently to the housing 102. Further, by means of fluid circulation, for instance, air, water, or oil circulation, the heat may be dissipated to the environment from the housing 102.

[0029] The supporting element 110, disposed within the housing 102, includes an over-molded body and the elastic member 108 partially over- molded in the aforementioned body. Once assembled, the elastic member 108, integrally fixed to the supporting element 110 by being over-molded, pushes the module 112 towards the housing 102 and away from the supporting element 110. Accordingly, heat generated by the module 112, or at least one electronic component of the module 112, is conducted to the housing 102 from which circulation of cooling fluid, such as, air, water, oil, may be provided for heat dissipation. Moreover, even on exposure to vibrations, the elastic member 108 does not fail from the assembled condition; and in view of this structural integrity, an efficient heat conduction between the module 112 and the housing 102 is ensured. Further, an efficient cooling of the electric power converter 100 is also achieved.

[0030] In an example, the supporting element 110 includes an electrical conductive means, for instance, an electrical bus bar, over-molded in electrical insulating material. The electrical conductive means is configured to carry and distribute electric power, and therefore facilitates with normal operation of the electric power converter.

[0031] In the examples depicted, the housing 102 includes a top cover 104a and a bottom cover 104b. In the assembled condition, sandwiched in between the top cover 104a and the bottom cover 104b is the control module 106, the supporting element 110 and the module 112. The bottom cover 104b in said example is a heat sink for dissipating heat generated by at least one electronic component of the module 112. The bottom cover 104b therefore serves a dual purpose, one of which is to function as an enclosure for the components within the cavity 114; and the second function being that of a heat sink for dissipating heat generated by the module 112. In said example, the elastic member 108 pushes the module 112 towards the bottom cover 104b, or heat sink, accordingly reducing the distance for heat conduction from the module 112 to the bottom cover 104b. Further, upon circulation of cooling fluid, the heat from the bottom cover 104b may then be dissipated.

[0032] FIG. 2 depicts the exploded view of the electric power converter 100 of FIG. 1, however, excluding the top cover 104a and the control module 106 for the sake of simplicity in illustration. The electric power converter 100 may have more than one module 112 configured in the above described manner. The number of modules 112 may vary depending on application. For instance, in an application where the electric power converter 100 is used for a rotary electrical machine having a three phase stator, there may be three such modules 112, each module 112 for each phase of said stator. Other instance may also exist in which the electric power converter 100 is used for a rotary electric machine having a six-phase stator. In the aforementioned instance, the electric power converter 100 may have three modules 112, each of the three modules 112 controlling two phases of the six -phase stator. The electric power converter 100, depicted in figures, is an example having three of such modules 112, though the perspective views illustrated in FIGs. 1 and 2 only show two out of the three modules 112. Accordingly, each module 112 is associated with an elastic member 108 over-molded in the supporting element 110. Therefore, as illustrated in FIG. 2, for each module 112 there is one elastic member 108 integrally fixed by means of over-molding in the supporting element 108. Hence, once assembled, the modules 112 are pushed towards the bottom cover 104, thereby facilitating thermal contact between the modules 112 and the bottom cover 104b. Specifically, the modules 112 are pushed in a direction parallel to axis X-X\ The axis X-X' defines a direction along which the components of the electric power converter 100 is assembled or dis-assembled. Accordingly, heat generated by the modules 112 are efficiently conducted to the bottom cover 104b, or heat sink, and then dissipated to the environment via cooling fluid, such as, water, oil, or air. Therefore, since the elastic members 108 are over-molded in the supporting element 110, structural integrity of the elastic members 108, and hence the assembly is ensured. Moreover, the operational integrity of the electric power converter 100 is safeguarded as heat generated by the modules 112 is efficiently dissipated.

[0033] FIG. 3 illustrates a zoomed in perspective of FIG. 2. Specifically, FIG. 3 illustrates an exploded view of the supporting element 110, the elastic member 108, the module 112, and the bottom cover 104b. FIG. 4 illustrates an assembled view of the components depicted in FIG. 3. For the sake of brevity, FIG. 3 and FIG. 4 are described herein in tandem.

[0034] The bottom cover 104b may include a locating pin 304 (shown in FIG. 3) that permits placement of the module 112 and the supporting element 110 during assembly. The module 112 and the supporting element 110 may each have a perforation 306a, 306b so that upon placement, the locating pin 304 is made to pass through said perforations 306a, 306b in a direction along axis X-X\ The axis X- X' is therefore an axis defining a direction of assembly, or dis-assembly. Consequently, any possibility of misalignment during assembly is eliminated. Once assembled, the supporting element 108 is arranged such that the elastic member 108, over-molded in the over-molded body of the supporting element 110, sits on the module 108 as shown in FIG. 4. The elastic member 108 exerts a pressure on the module 108 so that the module 108 is pressed onto the bottom cover 104b which is also a heat sink in one aspect. Heat generated by the module 108, for instance, a power semi-conductor, is then conducted to the bottom cover 104b from which the heat may then be dissipated to ambient environment.

[0035] In an aspect, the elastic member 108 includes two flat plates 300 that are globally parallel to a top surface 400 of the module 112. The arrangement of the two flat plates 300 is such that each of said plates 300 is perpendicular to the axis X-X\ Further, the two flat plates, namely, a first flat plate 300 and a second flat plate (not shown in FIGs. 3 & 4), are interconnected by a connecting arm 302. In an aspect, the connecting arm 302 extends between one end of the first flat plate 300 and one end of a second flat plate. The connecting arm 302 is arranged such that the two flat plates 300, 500 are displaced, or shifted, axially from one another in a direction parallel to the axis X-X\ The connecting arm 302 is adapted to transfer load from one of the two plates 300 to the other. Therefore, if a load is exerted on the first flat plate 300, said load is transferred, via the connecting arm 302, to the second flat plate, or a vice versa load transfer is possible. [0036] In another aspect, the first flat plate 300 is in direct contact with the top surface 400 of the module 112. Accordingly, once assembled, the first flat plate 300 pushes the module 112 towards the bottom cover 104b and away from the supporting element 110.

[0037] The elastic member 108 is only partially over-molded in the over-molded body of the supporting element 110. More specifically, in an aspect, the second flat plate, of the elastic member 108, is integrally molded in the over- molded body of the supporting element 100. Therefore, once assembled, pressure exerted on the second flat plate is transferred via the connecting arm 302 and the first flat plate 300, to the module 112. The module 112 is accordingly pushed towards the housing 102, specifically the bottom cover 104b (also a heat sink in one aspect), thereby allowing heat generated by the module 112 to be effectively conducted to the bottom cover 104b. From the bottom cover 104b, the heat may be dissipated to ambient air.

[0038] FIG. 5 depicts a cross-sectional view of the electric power converter 100 in accordance with the present subject matter. FIG. 5 exemplifies a cross-sectional view of the assembled electric power converter 100 shown in FIG. 4.

[0039] In accordance with the present subject matter, the elastic member 108 includes the first flat plate 300, as explained in the description above, and a second flat plate 500, both aforementioned flat plates 300, 500 being parallel to the top surface 400 of the module 112. The arrangement of the two flat plates 300 is such that each of said plates 300, 500 is perpendicular to the axis X-X'. Further, the connecting arm 302, that interconnects the two flat plates 300, 500, is arranged so that the second flat plate 500 is axially shifted from the first flat plate 300 along an axis parallel to X-X'.

[0040] In a non-limiting manner, the connecting arm 302 extends slantwise between the two flat plates 300, 500. In yet another example, the connecting arm 302 may be arranged, or oriented, to be parallel to axis X-X', and extending between the two flat plates 300, 500. In the example depicted, the connecting arm 302 extends slantwise between one end of the first flat plate 300 and one end of the second flat plate 500. Moreover, in said example, the second flat plate 500 is integrally molded in the over-molded body of the supporting element 110. Furthermore, a portion of the connecting arm 302 is also over-molded into the overmolded body of the supporting element 110. The over-molding of the aforementioned portion adds to the structural rigidity of the supporting element 110 and the elastic member 108. In addition, the connecting arm 302 provides flexibility to the elastic member 108 so that even on exposure to varying pressures, or loads, the elastic member 108 may flex such that the supporting element 110 displaces to and fro in the direction parallel to the X-X' axis. Furthermore, the pressure exerted on the first flat plate 300 is uniformly distributed, hence, the possibility of the first flat plate 300 buckling is eliminate. The structural integrity of the elastic member 108 is therefore maintained.

[0041] In one example, a thermally conductive material 502 is disposed between the module 112 and the housing 102, specifically between a bottom surface 500 of the module 112 and the bottom cover 104b of the housing 102. Therefore, as the elastic member 108 presses the module 112, an optimal thermal contact between the module 112 and the bottom cover 104b is achieved. Moreover, an optimal thermal conduction between the module 112 and the bottom cover 104b is achieved as the structural integrity of the elastic member 108, configured in the above- mentioned manner, is secured. In addition, as explained in the foregoing paragraph, the pressure exerted is uniformly distributed to the first flat plate 300.

[0042] The present subject matter also relates to an assembly that includes an electric machine (not shown) and an electric power converter 100 configured in the manner described above. The electric power converter 100 is adapted to be in electric communication with the electric machine. The electric power converter 100 therefore may control said machine by transferring electrical signals. [0043] In an example, the electric machine is a rotary electrical machine, an electric power source, an electric power storage, an electronic control unit, or a combination thereof.

[0044] In the example where the electrical power converter 100 is electrically connected to a rotary electrical machine, the rotary electrical machine may be controlled to operate as a motor (in a motor mode) or a generator (in a generator mode). It may also be said that the electric power converter 100 operates as a voltage converter that functions as a rectifier bridge in generator mode and/or as an inverter in the motor mode of the rotary electrical machine. Accordingly, the rotary electrical machine, an electro-mechanical device, preferably poly-phase, may convert electrical energy into mechanical energy, or vice versa. A rotary electrical machine, though typically used for driving motor vehicles, may have wide applications, such as, lawn mowers, drones, pumps, turbines, etc. In a scenario where the rotary electrical machine operates as a motor to drive a motor vehicle, the electric power converter 100 receives DC from an electric power source, converts DC to AC, and supplies it to a stator of the rotary electrical machine which then interacts with the rotor. In a scenario where the rotary electrical machine operates as a generator, for instance, when the motor vehicle is driven by an internal combustion (IC) engine, the rotor of the rotary electrical machine is driven thereby interacting with the stator to generate AC. The AC may then be converted to DC, by the electric power converter 100, for storage in an electric power storage. The electric power source and electric power storage, mentioned in the above scenarios, may be the same.

[0001] In the above mentioned example, the electric power converter 100 is included, or integrated, into the rotary electrical machine. However, in another example, the electric power converter 100, operating in the manner as described above, may not be integrated to the rotary electrical machine. In other words, it may exist as a separate component from the rotary electric machine, nonetheless remaining in electric connection with said machine to perform the operations as described in the above example. The present invention is applicable for both examples of electric power converters.

[0002] Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter. It is therefore contemplated that such modifications can be made without departing from the scope of the present subject matter is defined.