ELECTRONIC CONTROL UNIT

Abstract

An electronic control unit for an electrical machine of an electrically powered drive system is disclosed. The electronic control unit may include at least one semiconductor board, a baseplate, a holding bracket, and at least one resilient biaser. The at least one semiconductor board may include a plurality of power semiconductors. The baseplate may dissipate heat in the electronic control unit. The holding bracket may be attached to the baseplate. The at least one resilient biaser may be arranged between the holding bracket and the plurality of power semiconductors. The at least one resilient biaser may bias the plurality of power semiconductors towards the baseplate. The holding bracket may include at least one connector attaching the at least one resilient biaser to the holding bracket.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to European Patent Application No. EP22203845.7, filed on Oct. 26, 2022, the contents of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

The invention relates to an electronic control unit.

BACKGROUND

It is generally known to bias heat generating semiconductor packages of an electronic control device towards a heat sink in order to effectively dissipate the heat away from the semi-conductor device via the heat sink.

A known prior art electronic control device is disclosed in KR20080099111A. This describes a box-shaped housing having openings on both sides and an aluminum heat sink attached to one opening of the housing. Semiconductor switching elements of the electronic control device are arranged in the housing and the semiconductor switching elements are pressed towards the heat sink via a leaf spring which is attached to the heat sink by a screw.

Means for clamping a semi-conductor to a heat sink is also disclosed in U.S. Pat. No. 5,483,103A. Again a leaf spring is attached to a heat sink with a screw, and the leaf spring biases the semiconductors, in this case via a leveler, towards the heat sink.

An electronic power inverter for an electrical machine is also known in EP3609066B1. The power inverter comprises a housing with a semiconductor board, a capacitor board, power terminals and phase terminal studs. The semi-conductor board is biased towards the heat exchanger plate by a pressing plate which is attached to the heat exchanger plate by screws, whereby a busbar guide plate, a capacitor board and a damping plate are arranged between the semi-conductor board and the pressing plate.

SUMMARY

The electric control unit according to the invention has the advantage that the semiconductors can be biased towards a cooling baseplate using only a low number of components, reducing assembly time.

This object is achieved according to the invention with an electronic control unit for an electrical machine, the electronic control unit comprising at least one semiconductor board having a plurality of power semiconductors, a baseplate for dissipating heat generated in the electronic control unit, a holding bracket attached to the baseplate, and resilient biasing means arranged between the holding bracket and the plurality of power semiconductors for biasing the power semiconductors towards the baseplate, wherein the holding bracket comprises means for attaching the resilient biasing means to the holding bracket.

By providing the holding bracket with means for attaching the resilient biasing means there is no need to attach each of the springs, which press the power semiconductors onto the baseplate, with screws to the cooling baseplate. Therefore, the number of parts can be reduced and assembly time can be improved. Also, space can be saved compared to prior art designs whereby each spring is attached by a screw to the baseplate.

The electronic control unit can in particular be an electric power inverter.

The resilient biasing means is advantageously provided by a plurality of leaf springs. The leaf springs are therefore attached to the holding bracket, which is attached to the baseplate. The leaf springs each comprise a central fixing part for attaching the leaf spring to the holding bracket and a plurality of biasing arms which extend integrally from the central fixing part and contact one of the power semiconductors or the semiconductor board for biasing the power semiconductors towards the baseplate.

As the power semiconductors are provided on a semiconductor board, they do not in a first embodiment contact the baseplate directly, however the pressing of the semiconductors presses in turn the semiconductor board against the baseplate and the contact between the power semiconductor, the semiconductor board and the baseplate is especially good in the area of the heat generating power semiconductors due to the leaf springs pressing on the power semiconductors.

In an alternative embodiment the power semiconductors could be arranged on the side of the semiconductor board facing the baseplate, whereby the leaf springs could be arranged to contact the semiconductor board in the area of the power semiconductors, and the power semiconductors would be in direct contact with the heat dissipating baseplate.

The leaf spring is preferably made out of sheet metal.

In a preferred embodiment the leaf springs each comprise at least four biasing arms which extend integrally from the central fixing part and contact respectively one of the semiconductors or the semiconductor board for biasing the semiconductors towards the baseplate. The leaf spring is preferably punched from a single piece of sheet metal. In this way each leaf spring can bias four power semiconductors towards the baseplate, therefore reducing the number of parts required.

The leaf springs can comprise at least one fixing opening in the central fixing part. Preferably two fixing openings are provided in each leaf spring. Providing two fixing openings enables a non-rotational positioning of the leaf spring with respect to the holding bracket.

The means for attaching the resilient biasing means to the holding bracket comprises holding pins which project from the holding bracket. Advantageously the holding bracket and the holding pins can be formed integrally. The holding bracket with the integral holding pins is preferably made out of aluminium, for example by high pressure die casting. Alternatively, the holding bracket with the integral holding pins can be made out of plastic for reduced weight, in this case it can be made by injection molding. The holding bracket with holding pins can therefore be manufactured in one molding step, in order to reduce assembly time.

The holding pins extend through the corresponding fixing openings in the leaf springs, and the leaf springs are attached to the holding bracket by deformation of the holding pins. The ends of the holding pins are preferably deformed such that the leaf spring is not rigidly fixed to the holding bracket, but instead is fixed in a floating manner. This has the advantage that the pins are not overstrained and the spring can position itself correctly on the holding bracket when the applying a biasing force onto the semiconductors.

The holding bracket is attached to the baseplate by a plurality of screws. For this purpose, the holding bracket can have through-holes through which the screws extend. The holding bracket can be attached by screws to the baseplate, wherein the screws can be located at the edges or corners of the bracket spaced from the power semiconductors. The fixing screws of the holding bracket are therefore not located between the power semiconductors. In this way the electronic control unit can be made more compact.

The holding bracket is provided with at least one, preferably at least two positioning holes for receiving respectively a plurality of first positioning pins which are fixed to or received in the baseplate. The first positioning pins can also extend through positioning holes in the at least one semiconductor board. The holding bracket can therefore be accurately positioned with respect to the baseplate and/or the at least one semiconductor board.

The holding bracket comprises a plurality of second positioning pins for positioning a logic control board in relation to the holding bracket. The pins can be made out of metal, preferably steel. The second positioning pins extend from the holding bracket in a direction away from the baseplate.

The baseplate is made from a thermally conductive metal, preferably aluminum, and can comprises pins or fins from improved heat dissipation.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments will now be described by way of example only with reference to the accompanying drawings, in which:

FIG. 1 is a perspective view of an electronic control unit according to the invention,

FIG. 2 is an exploded view of the electronic control unit in FIG. 1[[.]],

FIG. 3 is a cross-sectional view of the electronic control unit according to the invention,

FIG. 4 is a bottom perspective view of a holding bracket according to the invention,

FIG. 5 is a top perspective view of a holding bracket according to the invention,

FIG. 6 is a perspective view of a leaf spring according to the invention,

FIG. 7 is a cross-section of part of the holding bracket.

DETAILED DESCRIPTION

FIGS. 1 and 2 show an electronic control unit 1 for an electrical machine according to the invention. FIG. 2 shows the electronic control unit 1 in an exploded view. The electronic control unit 1 can be for example an inverter unit for supplying three phase power to an electric motor. It could also be a converter unit for converting three phase power from a generator motor to DC power.

The electronic control unit 1 comprises at least one semiconductor board 2 having a plurality of power semiconductors 3. The power semiconductors generate heat when switching which must dissipated. For this purpose, a baseplate 4 for dissipating heat generated in the electronic control unit is provided. The baseplate 4 is preferably made of aluminum and can have a plurality of pins or fins 5 for improved cooling.

A holding bracket 6 is attached via screws 7 to the baseplate 4. Resilient biasing means in the form of leaf springs 8 are arranged between the holding bracket 6 and the plurality of power semiconductors 3 for biasing the power semiconductors 3 towards the baseplate, wherein the holding bracket 6 comprises means 9 for attaching the resilient biasing means 8 to the holding bracket 6.

By providing the holding bracket 6 with means 9 for attaching the leaf springs 8 there is no need to attach each of the springs, which press the power semiconductors onto the baseplate, with screws to the cooling baseplate.

As can be best seen in FIGS. 3 and 6, the leaf springs 8 each comprise a central fixing part 10 for attaching the leaf spring 8 to the holding bracket 6 and a plurality of biasing arms 11 which extend integrally from the central fixing part 10 and contact one of the power semiconductors 3 or the semiconductor board 2 for biasing the power semiconductors 3 towards the baseplate 4.

In the embodiment shown, the power semiconductors 3 are provided on the side of the semiconductor board 2 facing away from the baseplate 4 and therefore they do not contact the baseplate 4 directly, however the pressing of the semiconductors presses in turn the semiconductor board 2 against the baseplate 4 and the contact between the power semiconductor 3, the semiconductor board 2 and the baseplate 4 is improved in the area of the heat generating power semiconductors 3. There can also be a thermal heat transfer layer provided on the baseplate 4 in the area of the semiconductor board 2 to improve heat transfer away from the semiconductors 3.

In an alternative embodiment the power semiconductors 3 can be arranged on the side of the semiconductor board facing the baseplate 4, whereby the leaf springs 8 are then arranged to contact the semiconductor board 2 in the area of the power semiconductors, and the power semiconductors 3 are then in direct contact with the heat dissipating baseplate 4.

The leaf spring 8 is preferably made out of sheet metal, preferably punched out of a single sheet of metal. In the embodiment shown the leaf springs 8 each comprise four biasing arms 11 which extend integrally from the central fixing part 10 and contact respectively one of the semiconductors 3 for biasing the semiconductors 3 towards the baseplate 4. Each leaf spring 8 therefore presses four power semiconductors 3 towards the baseplate 4, therefore reducing the number of parts required. For a full bridge inverter with twelve power semiconductors 3 as shown in FIGS. 1 and 2, only three such leaf springs 8 are required to bias all the semiconductors 3 towards the baseplate 4.

As shown in FIG. 6 the leaf springs 8 comprise two fixing openings 12 in the central fixing part 10 to position the leaf spring 8 with respect to the holding bracket 6. The holding bracket 6 comprises holding pins 9 which project from the holding bracket 6 in a direction towards the baseplate 4. The holding bracket 6 and the holding pins 9 are formed integrally out of aluminium, for example by high pressure die casting. The holding bracket 6 with holding pins 9 can therefore be manufactured in one molding step, in order to reduce assembly time. Alternatively the holding bracket 6 and the holding pins 9 can be formed integrally out of a plastic material for reduced weight, for example by injection molding.

The holding pins 9 extend through the corresponding fixing openings 12 in the leaf springs 8, and the leaf springs 8 are attached to the holding bracket 6 by deformation of the holding pins 9. The ends of the holding pins 9 are preferably deformed such that the leaf spring 8 is not rigidly fixed to the holding bracket 6, but instead is fixed in a floating manner. This has the advantage that the pins are not overstrained and the spring can position itself correctly on the holding bracket when the applying a biasing force onto the semiconductors. To facilitate the deformation of the holding pins 9 they are provided with a conical recess 13 in the free ends of the holding pin 9, as shown in FIG. 7.

As mentioned above, the holding bracket 6 is attached to the baseplate 4 by a plurality of screws 7. For this purpose, the holding bracket 6 has a plurality of through-holes 14 through which the screws 7 extend. The screws 7 can be located at the edges or corners of the bracket 6 spaced from the power semiconductors 3. The fixing screws 7 of the holding bracket are therefore not located between the power semiconductors 3. In this way the electronic control unit can be made more compact.

The holding bracket 6 is further provided with at least two positioning holes 15 for receiving respectively a plurality of first positioning pins 16 which are fixed to or received in holes in the baseplate 4. The first positioning pins 16 can also extend through positioning holes 17 in the semiconductor board 2. The holding bracket 6 can therefore be accurately positioned with respect to the baseplate 4 and/or the at least one semiconductor board 2.

The holding bracket also has a plurality of second positioning pins 18 for positioning a logic control board (not shown) in relation to the holding bracket 6. The second positioning pins 18 extend from the holding bracket 6 in a direction away from the baseplate 4. The logic control board is also arranged on the side of the holding bracket 6 facing away from the baseplate 4 and comprises corresponding positioning holes or openings to receive the pins 18. The pins 18 can be made out of metal, preferably steel.

Claims

1. An electronic control unit for an electrical machine of an electrically powered drive system, the electronic control unit comprising: at least one semiconductor board including a plurality of power semi conductors;a baseplate for dissipating heat in the electronic control unit;a holding bracket attached to the baseplates; andat least one resilient biaser arranged between the holding bracket and the plurality of power semiconductors, the at least one resilient biaser biasing the plurality of power semiconductors towards the baseplate;wherein the holding bracket includes at least one connector attaching the at least one resilient biaser to the holding bracket.

2. The electronic control unit according to claim 1, wherein the at least one resilient biaser includes a plurality of leaf springs.

3. The electronic control unit according to claim 2, wherein the plurality of leaf springs each include a central fixing part and a plurality of biasing arms extending integrally from the central fixing part, the plurality of biasing arms biasing at least one associated power semiconductor of the plurality of power semiconductors towards the baseplate via contacting at least one of (i) the at least one associated power semiconductor and (ii) the at least one semiconductor board.

4. The electronic control unit according to claim 3, wherein: the plurality of biasing arms of at least one leaf spring of the plurality of leaf springs includes at least four biasing arms; andthe at least four biasing arms each bias a respective power semiconductor of the plurality of power semiconductors towards the baseplate via contacting at least one of (i) the respective power semiconductor and (ii) the at least one semiconductor board.

5. The electronic control unit according to claim 3, wherein the plurality of leaf springs each further include at least one fixing opening disposed in the central fixing part.

6. The electronic control unit according to claim 1, wherein: the at least one connector includes a plurality of holding pins projecting from the holding bracket; andthe holding bracket and the plurality of holding pins are formed integrally.

7. The electronic control unit according to claim 6, wherein: the at least one resilient biaser includes a plurality of leaf springs;the plurality of holding pins extend through a plurality of corresponding fixing openings of the plurality of leaf springs; andthe plurality of leaf springs are attached floatingly to the holding bracket via deformation of the plurality of holding pins.

8. The electronic control unit according to claim 7, wherein at least one leaf spring of the plurality of leaf springs includes two fixing openings of the plurality of fixing openings that position the at least one leaf spring with respect to the holding bracket.

9. The electronic control unit according to claim 1, wherein the holding bracket is attached to the baseplate via a plurality of screws.

10. The electronic control unit according to claim 9, wherein the plurality of screws are arranged at at least one of (i) at least one edge and (ii) at least one corner of the holding bracket, and are disposed spaced apart from the plurality of power semiconductors.

11. The electronic control unit according to claim 1, wherein the holding bracket further includes at least two positioning holes receiving respectively a plurality of positioning pins which are at least one of connected to and received in the baseplate.

12. The electronic control unit according to claim 1, wherein the holding bracket further includes a plurality of positioning pins extending in a direction away from the baseplate, and wherein the positioning pins are structured and arranged to position a control board in relation to the holding bracket.

13. The electronic control unit according to claim 1, wherein the base plate includes at least one of a plurality of heat dissipation pins and a plurality of heat dissipation fins.

14. The electronic control unit according to claim 1, further comprising a thermal heat transfer layer disposed on the baseplate in an area of the at least one semiconductor board.

15. The electronic control unit according to claim 1, wherein the plurality of power semiconductors are arranged on a surface of the at least one semiconductor board facing away from the baseplate and do not directly contact the baseplate.

16. The electronic control unit according to claim 15, wherein: the at least one resilient biaser includes a plurality of leaf springs; andthe plurality of leaf springs each bias the at least one semiconductor board against the baseplate via contacting and pressing at least one associated power semiconductor of the plurality of power semiconductors towards the baseplate.

17. The electronic control unit according to claim 1, wherein the plurality of power semiconductors are arranged on a surface of the at least one semiconductor board facing toward the baseplate.

18. The electronic control unit according to claim 17, wherein: the at least one resilient biaser includes a plurality of leaf springs; andthe plurality of leaf springs each bias at least one associated power semiconductor of the plurality of power semiconductors directly against the baseplate via contacting and pressing the at least one semiconductor board towards the baseplate.

19. The electronic control unit according to claim 6, wherein the plurality of holding pins each have a free end, an axial end face disposed at the free end, and a conical recess disposed in the axial end face.

20. An electronic control unit for an electrical machine of an electrically powered drive system, the electronic control unit comprising: a semiconductor board;a plurality of power semiconductors disposed on the semiconductor board;a baseplate structured and arranged to dissipate heat;a holding bracket attached to the baseplate, the holding bracket including a plurality of holding pins; anda plurality of leaf springs arranged between the holding bracket and the plurality of power semiconductors, the plurality of leaf springs biasing the plurality of power semiconductors towards the baseplate;wherein the plurality of leaf springs are floatingly attached to the holding bracket via the plurality of holding pins.