# Patent

## Title
Power module cooling system

## Abstract

A cooling system is operable to facilitate cooling a power module or other electronic assembly. The cooling system may be configured to facilitate cooling a DC/AC inverter or other electronic assembly where two power modules may be arranged in an opposing relationship relative to a coolant passageway. The opposing relationship may be suitable to minimizing a packaging size and footprint required to facilitate interacting both power modules with the coolant flow.

## Background
TECHNICAL FIELD
The present invention relates to power module cooling systems, such as but not limited to cooling systems operable with power modules configured to facilitate driving an electric motor with output from a DC/AC inverter.
BACKGROUND
Power modules may be used for any number of electronic applications where current and/or voltage manipulation is desired. Power modules, in particularly those operable to support relatively high current and voltage requirements, may generate significant amounts of heat during operation. Because the heat can negatively influence performance, it may be desirable to facilitate cooling of the power module. Accordingly, the present invention desires to provide a cooling system operable to facilitate the cooling of power modules.
SUMMARY
One non-limiting aspect of the present invention contemplates a power module cooling system comprising: a first power module having a first plurality of cooling fins; a second power module having a second plurality of cooling fins; a cold plate having a top side shaped to receive the first power module and a bottom side shaped to receive the second power module, the top side and the bottom side being spaced apart to define a fluid passageway into which the first and second plurality of cooling fins extend, the fluid passage extending between first and second apertures included within respective first and second lateral sides of the cold plate, the first aperture directing received fluid through the fluid passageway to the second aperture to facilitate cooling of the first and second plurality of cooling fins.
One non-limiting aspect of the present invention contemplates a first power module seal around an entire perimeter of a top side of the fluid passageway between the cold plate and the first power module and a second power module seal around an entire perimeter of a bottom side of the fluid passageway between the cold plate and the second power module, the first and second power module seals being operable to prevent fluid from leaking out of the fluid passageway.
One non-limiting aspect of the present invention contemplates a plurality of fastener apertures within the top side and the bottom side of the cold plate outboard of the fluid passageway and the first and second power module seals, the plurality of fastener apertures aligning with corresponding fastener apertures of the first and second power modules through which fasteners extend to secure the first power module and the second power module to the top side and the bottom side of the cold plate.
One non-limiting aspect of the present invention contemplates the fasteners apertures are operable with the fasteners to facilitate compressing the first power module against the first power module seal and the second power module against the second power module seal.
One non-limiting aspect of the present invention contemplates a first cooling manifold operable to exchange fluid with the first aperture and a second cooling manifold operable to exchange fluid with the second aperture.
One non-limiting aspect of the present invention contemplates a first manifold seal around an entire perimeter of the first aperture between the cold plate and the first manifold and a second manifold seal around an entire perimeter of the second aperture between the cold plate and the second manifold, the first and second manifold seals being operable to prevent fluid from leaking out of the fluid passageway.
One non-limiting aspect of the present invention contemplates a plurality of fastener apertures within the first and second lateral sides of the cold plate, the plurality of fastener apertures aligning with corresponding fastener apertures of the first and second power manifolds through which fasteners extend to secure the first manifold and the second manifold to the first and second lateral sides of the cold plate.
One non-limiting aspect of the present invention contemplates a capacitor having a height greater than a combined height of the first and second power modules and a width greater than the first power module, the capacitor having at least a first plurality of capacitor terminals connected to the first power module and a second plurality of capacitor terminals connected to the second power module.
One non-limiting aspect of the present invention contemplates a clamp bracket used to position the capacitor relative to the first and second power modules being fastened to at least two of the cold plate, the first cooling manifold, and the second coolant manifold, the clamp bracket aligning the first and second capacitor terminals with corresponding terminals of the first and second power modules.
One non-limiting aspect of the present invention contemplates the clamp bracket is not fastened to the capacitor.
One non-limiting aspect of the present invention contemplates the clamp bracket fastens to both of the cold plate and the first coolant manifold, wherein the second coolant manifold is shaped differently from the first coolant manifold such that the second manifold cannot be fastened to the clamp bracket.
One non-limiting aspect of the present invention contemplates outboard ends of the first plurality of cooling fins are position no more than 1 mm from outboard ends of the second plurality of cooling fins.
One non-limiting aspect of the present invention contemplates outboard ends of the first plurality of cooling fins are positioned no closer than 0.1 mm from outboard ends of the second plurality of cooling fins.
One non-limiting aspect of the present invention contemplates a cooling system for use with a DC/AC inverter, the DC/AC inverter having a first power module comprised at least of a plurality of first switches controlled with a first driver and a physically separate second power module comprised at least of a plurality of second switches controlled with a second driver, wherein each one of the plurality of first switches is electrically connected in parallel with at least a corresponding one of the plurality of second switches, each of the first and second power modules including a plurality of outwardly extending cooling fins, the cooling system comprising: a cold plate having a fluid passageway through which a cooling fluid flows in a longitudinal direction, the cold plate being configured to position the cooling fins of the first and second power modules in an opposing relationship within the fluid passageway to be cooled by the cooling fluid.
One non-limiting aspect of the present invention contemplates the opposing relationship is characterized by an outboard end of each cooling fin of the first power module being positioned no more than 1.0 mm from an outboard end of a correspondingly opposed one of the cooling fins of the second power module.
One non-limiting aspect of the present invention contemplates the cold plate includes opposed top and bottom apertures extending longitudinally across substantially the entire longitudinal direction, the cooling fins of the first and second power modules respectively extending through the opposed top and bottom apertures.
One non-limiting aspect of the present invention contemplates the cold plate includes opposed left and right apertures at correspondingly opposed longitudinal ends, the left and right apertures being transverse to the top and bottom apertures, the right aperture receiving the cooling fluid and the left aperture expelling the cooling fluid, wherein the left and right apertures are smaller than the top and bottom apertures.
One non-limiting aspect of the present invention contemplates cooling system further comprising: a left manifold configured to exchange the cooling fluid with the left aperture; a right manifold configured to exchange the cooling fluid with the right aperture; a capacitor having a first set of terminals electrically and mechanically connected to the first power module, a second set of terminals electrically and mechanically connected to the second power module, and a third set at terminals electrically and mechanically connected to an EMI filter; and a clamp bracket configured to secure the capacitor relative to the first and second module and the cold plate, the clamp bracket fastening at one portion to the cold plate and at another portion to the coolant manifold.
One non-limiting aspect of the present invention contemplates a cooling system wherein a height of the cold plate measured transversely to the longitudinal direction is less than a width of the cold plate measured in the longitudinal direction, and wherein a depth of the cold plate measured laterally to the longitudinal direction is greater than the height and less than the width.
One non-limiting aspect of the present invention contemplates a three-phase DC/AC inverter comprising: a first power module having a first plurality of switches operable to invert a DC input to a three-phase AC output and a first plurality of cooling fins; a separate second power module having a second plurality of switches matching the first plurality of switches and connected in parallel there with, the second power module including a second plurality of cooling fins; and a cold plate having a fluid passageway through which a cooling fluid flows in a longitudinal direction, the first plurality of cooling fins being positioned by the cold plate in an opposing manner to the second plurality of cooling fins to be cooled by the cooling fluid.



BRIEF DESCRIPTION OF THE DRAWINGS
The present invention is pointed out with particularity in the appended claims. However, other features of the present invention will become more apparent and the present invention will be best understood by referring to the following detailed description in conjunction with the accompany drawings in which:
FIG. 1 schematically illustrates a power module system as contemplated by one non-limiting aspect of the present invention.
FIG. 2 illustrates a power module cooling system as contemplated by one non-limiting aspect of the present invention.
FIG. 3 illustrates an assembly view of the power module cooling system as contemplated by one non-limiting aspect of the present invention.
FIG. 4 illustrates cooling fins in an opposing relationship as contemplated by one non-limiting aspect of the present invention.



DETAILED DESCRIPTION
As required, detailed embodiments of the present invention are disclosed herein; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention that may be embodied in various and alternative forms. The figures are not necessarily to scale; some features may be exaggerated or minimized to show details of particular components. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a representative basis for teaching one skilled in the art to variously employ the present invention.
FIG. 1 schematically illustrates a power module system 10 having a power module cooling system 12 as contemplated by one non-limiting aspect of the present invention. The power module system 10 is shown for exemplary and non-limiting purposes as being configured to facilitate AC powering of an electric motor and/or alternator 14 included within a vehicle (not shown) with DC energy supply from a high voltage (HV) battery 16 also included within the vehicle. The power module system 10 may include a DC connector 20 operable between an open and a closed position to facilitate connecting and disconnecting the HV battery 16 to an electromagnetic interference (EMI) filter 22. A DC link capacitor 24 may connected to the EMI filter 22 to further filter the DC output from the HV battery 16. The DC output of the capacitor 24 may be commonly provided to a first power module 30 connected in parallel with a second power module 32. The first and second power modules 30, 32 may be configured to facilitate DC/AC inversion of the DC output into an AC output sufficient for powering the motor/alternator 14.
The power module system 10 may include an AC connector system 34 to facilitate connecting the AC output to the motor/alternator. A current sensing system 36 may be included to facilitate sensing current provided to the motor/alternator 14, such as to facilitate control of the DC/AC inversion process. A control board 38 may include a signal connector 40 to a vehicle interface 42 of a vehicle bus (not shown). The control board 38 may receive feedback from the current sensors 36 and other devices/systems within the vehicle to facilitate controlling or directing the DC/AC inversion process. The control board 38 may cooperate with a first driver 46 configured to control the first power module 30 and a second driver 48 configured to control the second power module. The first and second drivers 46, 48 may be configured to respectively control a plurality of first and second switches included within each module 30, 32 such that the opening and closing of the switches 60, 62, 64, 66, 68, 70, 72, 74, 76, 78, 80, 82 can be coordinated to provide the desired AC output to the motor/alternator 14.
The first and second power modules 30, 32 are shown to be configured as insulated-gate bipolar transistors (IGBTs) for exemplary non-limiting purposes. The present invention, however, is unnecessary limited to this particular configuration or the use of these components. The present invention fully contemplates its use and application to virtually any type of power module system, including those in it may not rely upon switches and/or those that may be operable within non-vehicle-based systems. The exemplary description provided herein, however, is believed to be particularly beneficial in that it contemplates a particular configuration for electrically connecting the power modules 30, 32 in parallel to facilitate the DC/AC inversion process and cooling the first and second power modules 30, 32 with a cold plate 86 such that a packaging size of the power module system 10, or at least a portion of the power module system components, may be minimized without unduly sacrificing cooling capabilities.
The cold plate 86 is shown schematically in FIG. 1 to be generally positioned between the first and second power modules 30, 32. FIG. 2 illustrates the cold plate 86 in more detail and as configured as part of the power module cooling system 12 contemplated by one non-limiting aspect of the present invention. The cooling system 12 is shown to include a first coolant manifold 88 and a second manifold 90 configured to facilitate a coolant flow through a fluid passageway 92 included within the cold plate 86. FIG. 3 illustrates the power module cooling system 12 in more detail, and in particular, the fluid passage 92 through the cold plate 86, as contemplated by one non-limiting aspect of the present invention. A coolant fluid may be received at the first coolant manifold 88 and expelled from the second coolant manifold 90 such that the cooling fluid flows in a longitudinal direction through the cold plate 86 between corresponding first and second apertures 96, 98. The coolant fluid may comprise any suitable liquid, plasma, or gas having characteristic sufficient to facilitate cooling the first and second power modules 30, 32.
The first power module 30 may be received within a top side 100 of the cold plate 86 and the second power module 32 may be received within a matching bottom side 102 of the cold plate 86. The first power module 30 and the second power module 32 may be arranged in an opposing manner such that a bottom side 104, 106 of each is directed towards the other. The bottom side 104, 106 of each power module 30, 32 may include a plurality of cooling fins (only the second power module 32 Figures are shown and generally referred to with reference numeral 110). The cooling fins 110 may be metallic or other thermally conducting material. The cooling fins 110 may extend outwardly away from a first printed circuit board (PCB) 112 and second PCB 114 respectively associated with the first and second power modules 30, 32. The cooling fins 110 may be positioned in a diametrically opposed manner through corresponding top and bottom longitudinal openings 118, 120 in the cold plate 86. The cooling fins 110 may be positioned in this opposed manner so that a volume of the fluid flow passageway is minimized while still allowing both power modules 30, 32 to be cooled. While the power modules 30, 32 are shown to include a relatively large number of discrete cooling fins 110 shaped as blade terminals, the use of the fins 110 may be omitted entirely and/or the fins 110 may be shaped as larger components or in other configurations suitable to facilitate interactions with the coolant flow.
The cooling of the power modules 30, 32 through the cooling fins 110 may be maximized by maximizing the amount of fluid flowing contacting the cooling fins 110. This may be achieved by maximizing interference between the cooling fins 110 in the coolant flow. Optionally, the cooling fins 110 of the first power module 30 may be positioned at a distance X of no more than 1.0 mm from the cooling fins of the second power module, to maximize interference with the coolant flow as shown in FIG. 4. More preferably, to ensure the cooling fins 110 provide maximum interference with the coolant flow, the cooling fins of the first power module 30 may be positioned within 0.5 mm of the cooling fins 110 of the second power module 32. It may be desirable to maintain at least a 0.1 mm distance X between the opposed cooling fins 110 in order to ensure at least some coolant fluid is able to pass from the first coolant manifold 88 to the second coolant manifold 90 to a desired velocity, i.e., the velocity of coolant flow may be proportional to the distance X between the opposed cooling fins.
A volume of the coolant passageway 92 may be approximately equal to a width of the cold plate 86 measured in the longitudinal direction between the first and second aperture 96, 98 multiplied by a depth of the cold plate 86 measured in the lateral direction between ends of the first aperture 96 multiplied by a height of the cold plate 86 measured in the transverse direction corresponding with a thickness of the cold plate 86 equal to a separation between the top and bottom sides. The height of the coolant passageway 92 may optionally be less than a height of the first power module 30 such that the volume of the coolant passageway 92 is less than a volume comprising one of the first and second power modules 30, 32. In this manner, a coolant passage 92 having a volume somewhat less than the volume of one of the first and second power modules 30, 32 may be sufficient to facilitate simultaneously cooling both of first and second power modules 30, 32. The ability to cool multiple power modules 30, 32 with a fluid passageway 92 of minimal size may be beneficial in limiting the size and packaging requirements for the power module cooling system 12, which can be particularly beneficial when used within a vehicle.
The cold plate 86 may include a top seal 122 and a matching bottom seal (not shown) positioned around an entire outer perimeter of the respective top and bottom, longitudinal apertures 118, 120. The seals 122 may cooperate with the PCBs 112, 114 of the first and second power modules 30, 32 to facilitate sealing the coolant passageway 92. The cold plate may include apertures 130 (only one labeled) outboard of the seals 122 that align with apertures 132 (only one labeled) of the first and second power modules 30, 32. Fasteners (not shown) may be inserted through the apertures 130, 132 to press the first and second power module 30, 32 against the cold plate 86, and thereby, the top and bottom seals 122 to facilitate the sealing effects. Additional seals 136 (only left shown) may be included around the entire outer perimeter of the first and second apertures 96, 98 to facilitate a sealing arrangement with the respective first and second coolant manifolds 88, 90. Additional apertures 138 (only one shown) may be included to facilitate fastening the coolant manifolds to the cold plate to establish the sealing arrangement around the first and second apertures.
The capacitor 24 may be positioned relative to a back side of the cold plate 86 with a clamp bracket 140. The capacitor 24 may include a first row 142 and a second row 144 of a plurality of terminals for establishing the electrical connections with the corresponding first and second power modules 30, 32, such as to provide the electrical connections shown in shown in FIG. 1. The capacitor 24 may include a third row 146 of a plurality of terminals for establishing electrical connections with the EMI filter 22 (the top two terminals may establish the positive connection to the EMI filter 22 and the bottom two terminals may establish the negative connection to the EMI filter 22). The clamp bracket 140 may be configured to facilitate positioning the capacitor 24 relative to the power modules 30, 32 and the cold plate 86 such that the capacitor 24 is not directly fastened to either one of the power modules 30, 32 or the cold plate 86, other than by soldering or other electrical plus mechanical means used to connect to reporter terminals 142, 144. This arrangement may be beneficial in permitting the use of an off-the-shelf capacitor or without having to include recesses or other fastening points within the capacitor.
While exemplary embodiments are described above, it is not intended that these embodiments describe all possible forms of the invention. Rather, the words used in the specification are words of description rather than limitation, and it is understood that various changes may be made without departing from the spirit and scope of the invention. Additionally, the features of various implementing embodiments may be combined to form further embodiments of the invention.

## Claims

1. A power module cooling system comprising:
a first power module having a first plurality of cooling fins;
a second power module having a second plurality of cooling fins;
a cold plate having a top side shaped to receive the first power module and a bottom side shaped to receive the second power module, the top side and the bottom side being spaced apart to define a fluid passageway into which the first and second plurality of cooling fins extend, the fluid passageway extending between first and second apertures included within respective first and second lateral sides of the cold plate, the first aperture for receiving fluid directed through the fluid passageway to the second aperture to facilitate cooling of the first and second plurality of cooling fins;
a first cooling manifold operable to exchange fluid with the first aperture and a second cooling manifold operable to exchange fluid with the second aperture; and
a first cooling manifold seal around an entire perimeter of the first aperture between the cold plate and the first cooling manifold and a second cooling manifold seal around an entire perimeter of the second aperture between the cold plate and the second cooling manifold, the first and second manifold seals being operable to prevent fluid from leaking out of the fluid passageway.

2. The power module cooling system of claim 1 further comprising a first power module seal around an entire perimeter of a top side of the fluid passageway between the cold plate and the first power module and a second power module seal around an entire perimeter of a bottom side of the fluid passageway between the cold plate and the second power module, the first and second power module seals being operable to prevent fluid from leaking out of the fluid passageway.

3. The power module cooling system of claim 2 further comprising a plurality of fastener apertures within the top side and the bottom side of the cold plate outboard of the fluid passageway and the first and second power module seals, the plurality of fastener apertures aligning with corresponding fastener apertures of the first and second power modules through which fasteners extend to secure the first power module and the second power module to the top side and the bottom side of the cold plate.

4. The power module cooling system of claim 3 wherein the fasteners apertures are operable with the fasteners to facilitate compressing the first power module against the first power module seal and the second power module against the second power module seal.

5. The power module cooling system of claim 1 further comprising a plurality of fastener apertures within the first and second lateral sides of the cold plate, the plurality of fastener apertures aligning with corresponding fastener apertures of the first and second cooling manifolds through which fasteners extend to secure the first cooling manifold and the second cooling manifold to the first and second lateral sides of the cold plate.

6. The power module cooling system of claim 1 further comprising a capacitor having a height greater than a combined height of the first and second power modules and a width greater than the first power module, the capacitor having at least a first plurality of capacitor terminals connected to the first power module and a second plurality of capacitor terminals connected to the second power module.

7. The power module cooling system of claim 6 further comprising a clamp bracket used to position the capacitor relative to the first and second power modules being fastened to at least two of the cold plate, the first cooling manifold, and the second cooling manifold, the clamp bracket aligning the plurality of capacitor terminals with corresponding terminals of the first and second power modules.

8. The power module cooling system of claim 7 wherein the clamp bracket is not fastened to the capacitor.

9. The power module cooling system of claim 7 wherein the clamp bracket fastens to both of the cold plate and the first cooling manifold, wherein the second cooling manifold is shaped differently from the first cooling manifold such that the second cooling manifold cannot be fastened to the clamp bracket.

10. The power module cooling system of claim 1 wherein outboard ends of the first plurality of fins are position no more than 1 mm from outboard ends of the second plurality of fins.

11. The power module cooling system of claim 1 wherein outboard ends of the first plurality of fins are positioned no closer than 0.1 mm from outboard ends of the second plurality of fins.

12. A cooling system for use with a DC/AC inverter, the DC/AC inverter having a first power module comprised at least of a plurality of first switches controlled with a first driver and a physically separate second power module comprised at least of a plurality of second switches controlled with a second driver, wherein each one of the plurality of first switches is electrically connected in parallel with at least a corresponding one of the plurality of second switches, each of the first and second power modules including a plurality of outwardly extending cooling fins, the cooling system comprising:
a cold plate having a fluid passageway through which a cooling fluid flows in a longitudinal direction, the cold plate being configured to position the cooling fins of the first and second power modules in an opposing relationship within the fluid passageway to be cooled by the cooling fluid, wherein the cold plate includes opposed top and bottom apertures extending longitudinally across substantially the entire longitudinal direction, the cooling fins of the first and second power modules respectively extending through the opposed top and bottom apertures, and wherein the cold plate includes opposed left and right apertures at correspondingly opposed longitudinal ends, the left and right apertures being transverse to the top and bottom apertures, the right aperture receiving the cooling fluid and the left aperture expelling the cooling fluid, wherein the left and right apertures are smaller than the top and bottom apertures;
a left manifold configured to exchange the cooling fluid with the left aperture;
a right manifold configured to exchange the cooling fluid with the right aperture;
a capacitor having a first set of terminals electrically and mechanically connected to the first power module, a second set of terminals electrically and mechanically connected to the second power module, and a third set of terminals electrically and mechanically connected to an EMI filter; and
a clamp bracket configured to secure the capacitor relative to the first and second power module and the cold plate, the clamp bracket fastening at one portion to the cold plate and at another portion to at least one of the left manifold and the right manifold.

13. The cooling system of claim 12 wherein the opposing relationship is characterized by an outboard end of each cooling fin of the first power module being positioned no more than 1.0 mm from an outboard end of a correspondingly opposed one of the cooling fins of the second power module.

14. The cooling system of claim 12 wherein a height of the cold plate measured transversely to the longitudinal direction is less than a width of the cold plate measured in the longitudinal direction, and wherein a depth of the cold plate measured laterally to the longitudinal direction is greater than the height and less than the width.

15. A three-phase DC/AC inverter comprising:
a first power module having a first plurality of switches operable to invert a DC input to a three-phase AC output and a first plurality of cooling fins;
a separate second power module having a second plurality of switches matching the first plurality of switches and connected in parallel therewith, the second power module including a second plurality of cooling fins; and
a cold plate having a fluid passageway through which a cooling fluid flows in a longitudinal direction, the first plurality of cooling fins being positioned by the cold plate in an opposing manner to the second plurality of cooling fins in order to be cooled by the cooling fluid, the fluid passageway extending between first and second apertures included within respective first and second lateral sides of the cold plate, the first aperture for receiving fluid directed through the fluid passageway to the second aperture to facilitate cooling of the first and second plurality of cooling fins;
a first cooling manifold operable to exchange fluid with the first aperture and a second cooling manifold operable to exchange fluid with the second aperture; and
a plurality of fastener apertures within the first and second lateral sides of the cold plate, the plurality of fastener apertures aligning with corresponding fastener apertures of the first and second cooling manifolds to receive fasteners to secure the first cooling manifold and the second cooling manifold to the first and second lateral sides of the cold plate.