An electronic control unit

Abstract

The present invention relates to an electronic control unit (100). The electronic control unit (100) has one or more printed circuit boards (110) configured to support and electrically connect one or more electrical components (112) of the electronic control unit (100). Further, one or more bus capacitors (120) are attached to one of the one or more printed circuit boards (110). The one or more printed circuit boards (110) are attached to an inner face (130A) of the heat sink (130), and one or more fins (136) are provided on an outer face (130B) of the heat sink (130), thereby allowing heat from at least the one or more electrical components (112) to be released into the atmosphere. The inner face (130A) of the heat sink (130) having a recess (132) configured to receive the one or more bus capacitors (120).

Description

[0001] AN ELECTRONIC CONTROL UNIT

[0002] FIELD OF THE INVENTION

[0003]

[0001] The present invention relates to an electronic control unit. More particularly, the present invention relates to a configuration of a compact electronic control unit.

[0004] BACKGROUND OF THE INVENTION

[0005]

[0002] Conventionally, in vehicles, especially in electric vehicles or vehicles using a motorgenerator such as an ISG, a motor controller is an integral part of drivetrain. Specifically in the context of a motor controller for an electric vehicle drivetrain, the motor controller takes input power from a battery and applies three phase alternating current to a three-phase motor to generate torque for providing traction force to the vehicle.

[0006]

[0003] A typical motor controller consists of electrolytic capacitors, MOSFET / IGBT based multi-phase H-Bridge and other peripherals like microcontroller, gate drivers etc. to control this multi-phase H-Bridge. Based on the power requirements, a motor controller may be required to supply several tens or hundreds amperes of current. Such high currents in the motor controller results in heat generation from MOSFETs, IGBTs, current sensing resistors (shunts), electrolytic capacitors etc.

[0007]

[0004] To dissipate the heat generated from these components, heat sinks are typically used to transfers heat from its source to ambient environment. Typically, heat dissipation ability of the controller is determined by the heat sink size and therefore overall weight and volume of the controller is heavily influenced by the size of the heat sink. In typical motor controllers, the heat sink is attached close to the power switches as these are the elements in the motor controller that generate the most heat. The Printed Circuit Board or the PCB has a top side and a bottom side. The power switches are connected on to the top side of the PCB. The bottom side of the PCB is connected to the heat sink. This kind of connection of the heat sink to the PCB results in height increase below the PCB because the heatsink is typically bulky.

[0008]

[0005] Another component that has a significant contribution to the overall height of the motor controller is electrolytic capacitor which is generally placed on the top side of the PCB, since the bottom side of the PCB is covered with the heat sink, resulting in height increase of the motor controller on top side as well as the bottom side of the PCB. Thus, conventional controllers have a large height at a top as well as a bottom side, resulting in overall weight and volume increase of the motor controller.

[0009]

[0006] Since the motor controller is to be mounted on a vehicle, where space for packaging is limited, it is required that the size of the motor controller be optimised without compromising heat dissipation ability of the controller.

[0010]

[0007] Thus, there is a need in the art for an electronic control unit which addresses at least the aforementioned problems.

[0011] SUMMARY OF THE INVENTION

[0012]

[0008] In one aspect of the invention, the present invention is directed towards an electronic control unit. The electronic control unit has one or more printed circuit boards. The one or more printed circuit boards are configured to support and electrically connect one or more electrical components of the electronic control unit. One or more bus capacitors are attached to one of the one or more printed circuit boards. The electronic control unit has a heat sink. The heat sink has an inner face and an outer face. The one or more printed circuit boards are attached to the inner face of the heat sink, thereby allowing heat from at least the one or more electrical components to be released into the atmosphere. The inner face of the heat sink having a recess configured to receive the one or more bus capacitors.

[0013]

[0009] In an embodiment of the invention, the one or more electrical components includes one or more power switches.

[0010] In a further embodiment of the invention, an air gap is provided between the recess and the one or more bus capacitors. In an alternative embodiment of the invention, the air gap between the recess and the one or more bus capacitors is filled with a thermal interface material, thereby thermally connecting the one or more bus capacitors to the heat sink for allowing heat from the one or more bus capacitors to be released into the atmosphere.

[0014] [Oi l] In a further embodiment of the invention, the one or more printed circuit boards includes a first circuit board. The first circuit board has a top surface and a bottom surface.

[0015]

[0012] In a further embodiment of the invention, the one or more power switches are disposed on the top surface of the first circuit board and are thermally connected to the inner face of the heat sink, and the one or more bus capacitors are disposed on the bottom surface of the first circuit board.

[0016]

[0013] In an alternative embodiment of the invention, the one or more power switches are disposed on the bottom surface of the first circuit board and are thermally connected to the inner face of the heat sink. The one or more bus capacitors are disposed on the bottom surface of the first circuit board.

[0017]

[0014] In a further embodiment of the invention, the inner face of the heat sink has one or more receiving sections. Each receiving section is configured to receive one of the one or more power switches.

[0018]

[0015] In a further embodiment of the invention, the one or more printed circuit boards include a first circuit board configured to receive the one or more power switches, and a second circuit board configured to receive one or more bus capacitors.

[0019]

[0016] In a further embodiment of the invention, the one or more power switches are attached on a top surface of the first circuit board, and the one or more bus capacitors are attached on a bottom surface of the second circuit board.

[0017] In a further embodiment of the invention, the outer face of the heat sink has a plurality of fins exposed to atmosphere. The plurality of fins allow the heat from the one or more electrical components to be released into the atmosphere.

[0020]

[0018] In a further embodiment of the invention, the outer face of the heat sink includes a flat portion and a projecting portion. The projecting portion projects outward from the flat portion and is provided to accommodate the recess on the inner face of the heat sink. The plurality of fins are provided on the flat portion of the outer face of the heat sink.

[0021]

[0019] In a further embodiment of the invention, the electronic control unit has a cover member configured to be attached to the heat sink thereby defining a space therebetween. Herein, the one or more printed circuit boards are accommodated in the space defined between the heat sink and the cover member.

[0022] BRIEF DESCRIPTION OF THE DRAWINGS

[0023]

[0020] Reference will be made to embodiments of the invention, examples of which may be illustrated in accompanying figures. These figures are intended to be illustrative, not limiting. Although the invention is generally described in context of these embodiments, it should be understood that it is not intended to limit the scope of the invention to these particular embodiments.

[0024] Figure 1 illustrates an exploded perspective view of an electronic control unit, in accordance with an embodiment of the invention.

[0025] Figure 2 illustrates another exploded view of the electronic control unit, in accordance with an embodiment of the invention.

[0026] Figure 3 illustrates a sectional view of the electronic control unit, in accordance with an embodiment of the invention.

[0027] Figure 4 illustrates another exploded view of the electronic control unit, in accordance with an embodiment of the invention. Figure 5 illustrates another exploded view of the electronic control unit, in accordance with an embodiment of the invention.

[0028] Figure 6 illustrates another sectional view of the electronic control unit, in accordance with an embodiment of the invention.

[0029] Figure 7 illustrates another exploded view of the electronic control unit, in accordance with an embodiment of the invention.

[0030] Figure 8 illustrates another sectional view of the electronic control unit, in accordance with an embodiment of the invention.

[0031] DETAILED DESCRIPTION OF THE INVENTION

[0032]

[0021] The present invention relates to an electronic control unit. More particularly, the present invention relates to a configuration of a compact electronic control unit. The electronic control unit of the present invention is typically used as a control unit or a motor controller for a drivetrain of an electric vehicle such as a two wheeled vehicle, or a three wheeled vehicle, or a four wheeled vehicle, or other multi-wheeled vehicles as required. However, it should be understood that the electronic control unit as illustrated may find its application in any other automotive or non-automotive application using an electronic control unit as required.

[0033]

[0022] Figure 1 illustrates an exploded perspective view of an electronic control unit 100, in accordance with an embodiment of the invention. As illustrated, the electronic control unit 100 comprises one or more printed circuit boards 110. The one or more printed circuit boards 110 are configured to support and electrically connect one or more electrical components 112 of the electronic control unit 100. In an embodiment, each of the one or more printed circuit boards 110 are in the form of a laminated sandwich structure of conductive and insulating layers. Herein, each conductive layer is provided with a pattern of features that perform similar to wires on a flat surface. The conductive layers are etched from one or more sheet layers of copper laminated onto and / or between sheet layers of a non-conductive substrate or insulating material. In operation, the one or more electrical components 112 are fixed to conductive pads on the outermost conductive layers designed to receive terminals of the one or more electrical components 112, thereby fastening the one or more electrical components 112 to the printed circuit board 110, both electronically as well as mechanically. The different layers are then interconnected with each other to form the printed circuit board 110.

[0034]

[0023] In an embodiment, the one or more electrical components 112 comprise one or more power switches 114. In another embodiment, the electronic control unit 100 is configured to control a motor, and the one or more power switches 114 are provided for controlling the motor. More specifically, the electronic control unit 100 is configured to control a traction motor that is a part of a drivetrain of an electric vehicle. The one or more power switches 114 provide an electrical connection between the source, such as a battery of the vehicle, to a load such as the traction motor or to the ground. The one or more power switches 114 interrupt or complete an electric circuit that supplies power to the load, thereby interrupting and allowing power supply from the battery to the one or more phases of the traction motor as per requirement, to suitably drive the traction motor. In an embodiment, the one or more power switches 114 comprises MOSFETs or IGBTs. In an embodiment, the one or more electrical components 112 of the electronic control unit 100 further includes, but not limited to, a microcontroller, a plurality of gate drivers for driving the one or more power switches 114 as per requirement, and a current sensing circuitry.

[0035]

[0024] As further illustrated in Figure 1, the electronic control unit 100 further comprises a heat sink 130. The heat sink 130 has an inner face 130A and an outer face 130B. The outer face 130B of the heat sink 130 is exposed to the ambient atmosphere. In an embodiment, a plurality of fins 136 are provided on the outer face 130B of the heat sink 130, which facilitates the dissipation of heat from the heat sink 130. The presence of plurality of fins 136 on the outer face 130B of the heat sink 130 increases the overall surface area of the heat sink 130 available for heat transfer to the atmosphere, thereby aiding in heat dissipation by the heat sink 130. Herein, the one or more printed circuit boards 110 are attached to inner face 130A of the heat sink 130 thereby allowing heat from at least the one or more electrical components 112 to be released into the atmosphere.

[0036]

[0025] Herein, since the one or more electrical components 112 are mechanically as well as electrically attached to the one or more printed circuit boards 110, heat generated by the one or more electrical components 112 such as the power switches 114, is conducted to the one or more printed circuit boards 110, and thereafter conducted to the heat sink 130, through which the heat is then released into the atmosphere. Thus, by provision of the heat sink 130, the heat generated by the one or more electrical components 112 is released into the atmosphere. In an embodiment, to further facilitate the heat transfer between the one or more electrical components 112, the one or more printed circuit boards 110 and the heat sink 130, a thermal interface material is provided between the one or more electrical components 112, the one or more printed circuit boards 110 and the heat sink 130.

[0037]

[0026] As further illustrated in Figure 1, the electronic control unit 100 further has one or more bus capacitors 120. The one or more bus capacitors 120 are attached to the one or more printed circuit boards 110. The one or more bus capacitors 120 are electrolytic capacitors provided in the electronic control unit 100 so as to reduce voltage ripple across the DC terminals of the electronic control unit 100, which are connected to the battery.

[0038]

[0027] Herein, the inner face 130A of the heat sink 130 has a recess 132. The recess 132 is configured to receive the one or more bus capacitors 120, thereby accommodating the one or more bus capacitors 120 within the heat sink 130. Thus, the one or more bus capacitors 120 and the heat sink 130 which would conventionally be provided on opposite sides of the one or more printed circuit boards 110, in the present invention, are provided on the same side with the one or more bus capacitors 120 being accommodated within the recess 132 of the heat sink 130. Such a configuration allows for a smaller overall size and reduction in height of the electronic control unit 100 since the one or more bus capacitors 120 and the heat sink 130 are provided on the same side of the one or more printed circuit boards 110.

[0028] In an embodiment, for dissipation of heat by the heat sink 130 in an efficient manner, the outer face 13 OB of the heat sink 130 comprises the plurality of fins 136 exposed to atmosphere, which allows the heat from the one or more electrical components 112 to be released into the atmosphere. The presence of plurality of fins 136 on the outer face 13 OB of the heat sink 130 increases the overall surface area of the heat sink 130 available for heat transfer to the atmosphere, thereby aiding in heat dissipation by the heat sink 130.

[0039]

[0029] In an embodiment, the outer face 130B of the heat sink 130 has a flat portion 138 (shown in Figure 3) and a projecting portion 138A (shown in Figure 3). As illustrated, the projecting portion 138A projects outward from the flat portion 138. The projecting portion 138A is provided to accommodate the recess 132 on the inner face 130A of the heat sink 130. Herein, the plurality of fins 136 are provided on the flat portion 138 of the outer face 130A of the heat sink 130. This means that the plurality of fins 136 are only provided on the flat portion 138 of the outer face 130A while not being provided on the projecting portion 138A of the outer face 130A. This further prevents an increase in the height of the electronic control unit 100, since the plurality of fins 136 are only provided on the flat portion 138, and not on the outwardly extending projecting portion 138A. In other words, the part of the outer face 130B of the heat sink 130 which lies below the one or more electronic components 112 is provided with the plurality of fins 136, while no fins are provided on the part of the outer face 130B that lies below the one or more bus capacitors 120.

[0040]

[0030] In an embodiment, as illustrated in Figure 2, the electronic control unit 100 comprises a cover member 140. The cover member 140 is configured to be attached to the heat sink 130 thereby defining a space therebetween. The one or more printed circuit boards 110 are accommodated in the space defined between the heat sink 130 and the cover member 140. The electronic control unit 100 of the present invention, wherein the one or more bus capacitors 120 are provided within the recess 132, ensures that no provisions need to be made in the cover member 140 for accommodating the one or more bus capacitors 120, and the cover member 140 remains substantially flat only to primarily cover the one or more printed circuit boards 110, thereby reducing overall height and size of the electronic control unit 100.

[0041]

[0031] In an embodiment, in the electronic control unit 100, an air gap is provided between the recess 132 and the one or more bus capacitors 120. This means that although the one or more bus capacitors 120 are accommodated within the recess 132, the one or more bus capacitors 120 are not in physical contact with the recess 132 and thus the heat sink 130. This ensures that the heat from the heat sink 130 does not have a deterring effect on the one or more bus capacitors 120. In an alternative embodiment, wherein the heat sink 130 is to be utilised to dissipate heat generated by the one or more electrical components 112 as well as the one or more bus capacitors 120, the air gap between the recess 132 and the one or more bus capacitors 120 is filled with a thermal interface material, thereby thermally connecting the one or more bus capacitors 120 to the heat sink 130 for allowing heat from the one or more bus capacitors 120 to be released into the atmosphere. Thus, the same heat sink 130 is utilised for heat dissipation from the one or more electrical components 112 as well as the one or more bus capacitors 120, thus eliminating the requirement of a dedicated heat sink for cooling the one or more bus capacitors 120, further aiding in reduction of overall size of the electronic control unit.

[0042]

[0032] As further referenced in Figure 1 and Figure 2, the one or more printed circuit boards 110 comprise a first circuit board 116. Herein, the first circuit board 116 having a top surface 116A and a bottom surface 116B. In the embodiment depicted in Figure 2 and Figure 3, the one or more power switches 114 are disposed on the top surface 116A of the first circuit board 116 and are thermally connected to the inner face 130A of the heat sink 130. Further, and the one or more bus capacitors 120 are disposed on the bottom surface 116B of the first circuit board 116. Thus, the heat from the one or more power switches 114 is dissipated by the heat sink 130 by virtue of the thermal connection between the one or more power switches 114 and the heat sink 130 while ensuring that the one or more bus capacitors 120 are accommodated within the recess 132 of the heat sink 130. The one or more bus capacitors 120 being accommodated in the recess 132 is specifically illustrated in Figure 3. In this embodiment, the inner face 130A of heat sink 130 receiving the first circuit board 116 is flat, so as to receive the first circuit board 116 and the plurality of fins 136 are provided on the outer face 130B of the heat sink 130.

[0043]

[0033] In an alternative embodiment as illustrated in Figure 4, Figure 5 and Figure 6, the one or more power switches 114 are disposed on the bottom surface 116B of the first circuit board 116 and are thermally connected to the inner face 130A of the heat sink 130. Further, the one or more bus capacitors 120 are disposed on the bottom surface 116B of the first circuit board 116. Thus, the heat from the one or more power switches 114 is dissipated by the heat sink 130 by virtue of the thermal connection between the one or more power switches 114 and the heat sink 130 while ensuring that the one or more bus capacitors 120 are accommodated within the recess 132 of the heat sink 130. The one or more bus capacitors 120 being accommodated in the recess 132 is specifically illustrated in Figure 6.

[0044]

[0034] In this embodiment, to as to accommodate the one or more power switches 114 provided at the bottom surface 116B of the first circuit board 116, the inner face 130A of the heat sink 130 comprises one or more receiving sections 134. Each receiving section 134 is configured to receive one of the one or more power switches 114. In the embodiment depicted in Figure 4, the one or more receiving sections 134 comprises one or more slots, wherein each slot is configured to receive the one of the one or more power switches 114 that are projecting outwardly from the bottom surface 116B of the first circuit board 116. In an alternative embodiment, the one or more receiving sections 134 comprises one or more protrusions, wherein each protrusion is configured to receive the one of the one or more power switches 114. In an alternative embodiment, the inner face 130A of heat sink 130 receiving the first circuit board 116 is flat, with a gap between the inner face 130A of the heat sink 130 and the bottom surface 116B of the first circuit board 116, thereby accommodating the one or more power switches 114 in the gap. Further, the plurality of fins 136 are provided on the outer face 130B of the heat sink 130.

[0035] For electronic control units 100 that handle a very large amount of current, for example when the electronic control unit 100 is a motor controller for large vehicle, separate printed circuit boards 110 are required to accommodate the one or more power switches 114 and the one or more bus capacitors 120. Accordingly, in an alternative embodiment as illustrated in Figure 7 and Figure 8, the one or more printed circuit boards 110 comprise the first circuit board 116 configured to receive the one or more power switches 114, and a second circuit board 118 configured to receive one or more bus capacitors 120.

[0045]

[0036] As referenced in Figure 7 and Figure 8, the one or more power switches 114 are attached on a top surface 116A of the first circuit board 116, and the one or more bus capacitors 120 are attached on a bottom surface of the second circuit board 118. Thus, the heat from the one or more power switches 114 is dissipated by the heat sink 130, by virtue of the thermal connection between the one or more power switches 114 and the heat sink 130 via the first circuit board 116. Further, it is also ensured that the one or more bus capacitors 120 provided on the bottom surface 118B of the second circuit board 118, are accommodated within the recess 132 of the heat sink 130.

[0046]

[0037] In an embodiment, in the electronic control unit 100, the air gap is provided between the recess 132 and the one or more bus capacitors 120. This means that although the one or more bus capacitors 120 are accommodated within the recess 132, the one or more bus capacitors 120 are not in physical contact with the recess 132 and thus the heat sink 130. This ensures that the heat from the heat sink 130 does not have a deterring effect on the one or more bus capacitors 120. In an alternative embodiment, wherein the heat sink 130 is to be utilised to dissipate heat generated by the one or more electrical components 112 as well as the one or more bus capacitors 120, the air gap between the recess 132 and the one or more bus capacitors 120 is filled with a thermal interface material, thereby thermally connecting the one or more bus capacitors 120 to the heat sink 130 for allowing heat from the one or more bus capacitors 120 to be released into the atmosphere. Thus, the same heat sink 130 is utilised for heat dissipation from the one or more power switches 114 as well as the one or more bus capacitors 120. The one or more bus capacitors 120 being accommodated in the recess 132 is specifically illustrated in Figure 8. In these embodiments, the inner face 130A of heat sink 130 receiving the first circuit board 116 and the second circuit board 118 is flat, so as to receive the first circuit board 116 and the second circuit board 118, and the plurality of fins 136 are provided on the outer face 130B of the heat sink 130.

[0047]

[0038] Advantageously, the present invention provides an electronic control unit wherein the heat sink and the one or more bus capacitors are provided on the same side of the one or more printed circuit boards. More specifically, the one or more bus capacitors are accommodated within the recess in the heat sink, which eliminates the requirement of the heat sink and the one or more bus capacitors being accommodated on opposite sides of the one or more printed circuit boards. This allows for the overall size and height of the electronic control unit to be reduced.

[0048]

[0039] Further, since the reduction in overall size and height of the electronic control unit is achieved without a reduction in size and dimensions of the heat sink, thus ensuring that there is no negative effect or reduction in the heat dissipation capabilities of the electronic control unit. The electronic control unit of the present invention also ensures that a single heat sink is utilised for heat dissipation from the one or more electrical components as well as the one or more bus capacitors. This results in eliminating the requirement of a dedicated or separate heat sink for cooling the one or more bus capacitors, which further aids in reduction of overall size of the electronic control unit.

[0049]

[0040] The reduction in size of the electronic control unit, without hampering the heat dissipation capabilities of the electronic control unit, ensures that the electronic control unit can be packaged within limited packaging spaces such as in vehicles when the electronic control unit is utilised as a motor controller for a motor or a drivetrain of the vehicle.

[0041] While the present invention has been described with respect to certain embodiments, it will be apparent to those skilled in the art that various changes and modification may be made without departing from the scope of the invention as defined in the following claims.

Claims

CLAIMS1. An electronic control unit (100), comprising: one or more printed circuit boards (110), the one or more printed circuit boards (110) being configured to support and electrically connect one or more electrical components (112) of the electronic control unit (100); one or more bus capacitors (120), the one or more bus capacitors (120) being attached to one of the one or more printed circuit boards (110); and a heat sink (130), the heat sink (130) having an inner face (130A) and an outer face (130B), the one or more printed circuit boards (110) being attached to the inner face (130A) of the heat sink (130), thereby allowing heat from at least the one or more electrical components (112) to be released into the atmosphere, and the inner face (130A) of the heat sink (130) having a recess (132) configured to receive the one or more bus capacitors (120).

2. The electronic control unit (100) as claimed in claim 1, the one or more electrical components (112) comprises one or more power switches (114).

3. The electronic control unit (100) as claimed in claim 1, wherein an air gap is provided between the recess (132) and the one or more bus capacitors (120).

4. The electronic control unit (100) as claimed in claim 3, wherein the air gap between the recess (132) and the one or more bus capacitors (120) is filled with a thermal interface material, thereby thermally connecting the one or more bus capacitors (120) to the heat sink (130) for allowing heat from the one or more bus capacitors (120) to be released into the atmosphere.

5. The electronic control unit (100) as claimed in claim 2, wherein the one or more printed circuit boards (110) comprise a first circuit board (116), the first circuit board (116) having a top surface (116A) and a bottom surface (116B).

6. The electronic control unit (100) as claimed in claim 5, wherein the one or more power switches (114) are disposed on the top surface (116A) of the first circuit board (116) and are thermally connected to the inner face (130A) of the heat sink (130), and the one or more bus capacitors (120) are disposed on the bottom surface (116B) of the first circuit board (116).

7. The electronic control unit (100) as claimed in claim 5, wherein the one or more power switches (114) are disposed on the bottom surface (116B) of the first circuit board (116) and are thermally connected to the inner face (130 A) of the heat sink (130), and the one or more bus capacitors (120) are disposed on the bottom surface (116B) of the first circuit board (H6).

8. The electronic control unit (100) as claimed in claim 7, wherein the inner face (130A) of the heat sink (130) comprises one or more receiving sections (134), each receiving section (134) configured to receive one of the one or more power switches (114).

9. The electronic control unit (100) as claimed in claim 2, wherein the one or more printed circuit boards (110) comprise a first circuit board (116) configured to receive the one or more power switches (114), and a second circuit board (118) configured to receive one or more bus capacitors (120).

10. The electronic control unit (100) as claimed in claim 9, wherein the one or more power switches (114) are attached on a top surface (116A) of the first circuit board (116), and theone or more bus capacitors (120) are attached on a bottom surface of the second circuit board (H8).

11. The electronic control unit (100) as claimed in claim 1, wherein the outer face (130B) of the heat sink (130) comprises a plurality of fins (136) exposed to atmosphere, the plurality of fins (136) allowing the heat from the one or more electrical components (112) to be released into the atmosphere.

12. The electronic control unit (100) as claimed in claim 11, wherein the outer face (130B) of the heat sink (130) comprises a flat portion (138) and a projecting portion (138A), the projecting portion (138 A) projecting outward from the flat portion (138) and being provided to accommodate the recess (132) on the inner face (130A) of the heat sink (130), wherein the plurality of fins (136) are provided on the flat portion (138) of the outer face (130A) of the heat sink (130).

13. The electronic control unit (100) as claimed in claim 1, comprising a cover member (140) configured to be attached to the heat sink (130) thereby defining a space therebetween, wherein the one or more printed circuit boards (110) are accommodated in the space defined between the heat sink (130) and the cover member (140).

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