This invention relates generally to cooling electronics components, for example isolated-gate bipolar transistors (IGBT), semiconductor devices, capacitors and other components of an electronic device, such as, for example a power electronics module of a variable speed drive.
Power electronic devices are commonly used for controlling and/or manipulating the characteristics, for example the frequency and/or the voltage, of the electric power being supplied to a variety of electrically powered devices. For example, variable speed drives are commonly used in connection with variable speed motors for controlling the speed of the motor. Variable speed motors are used in connection with compressors, water pumps, fans and other devices. For example, refrigerant vapor compressors, such as, but not limited to, scroll compressors, reciprocating compressors and screw compressors, to enable driving the compression mechanism of the compressor at various operating speeds. As the operating speed of the compression mechanism is decreased, the output capacity of the compressor is decreased, and conversely as the operating speed of the compressor is increased, the output capacity of the compressor is increased. The variable speed drive is operative to vary the frequency of the electric power supplied to drive motor of the compressor, thereby varying the operating speed of the motor, and consequently the operating speed and output capacity of the compressor.
In operation, adequate cooling the power electronics devices, such as but not limited to variable speed drives, must be ensured by removing heat generated by the power electronics so as to maintain the reliability and the functionally of the power electronics devices.
In an aspect, a heat sink device is provided that is useful for cooling a power electronics module at a temperature below a specified operating threshold temperature.
In an aspect, a heat sink device is provided that is useful for cooling the power electronics of a variable speed drive housed in a sealed enclosure through which a flow of cooling air is directed over and across the heat sink device.
A heat sink device for cooling a power electronics module includes a base platform having a first surface and a second surface on opposite sides of the base platform, a plurality of upright members extending outwardly from the first surface of the base platform and defining a cavity wherein the power electronics module is disposed in conductive heat exchange relationship with the first surface of the base platform, and a plurality of heat transfer fins extending outwardly from the second surface of the base platform and defining a plurality of cooling air flow channels. In an embodiment, the plurality of heat transfer fins may be disposed in parallel spaced relationship at a uniform spacing side-to-side. A fan may be disposed in operative association with the plurality of cooling air flow channels for passing a flow of cooling air through the plurality of cooling air flow channels in convective heat exchange relationship with the plurality of heat transfer fins. The ratio of the fin spacing to a thickness of a base portion of each fin of the plurality of heat transfer fins may be in the range from 2 to 3 inclusive. In an embodiment, the plurality of heat transfer fins may comprise flat plate fins having a uniform thickness. In an embodiment, the plurality of heat transfer fins may comprise a plurality of tapered fins, each tapered fin having a base portion and a tip portion with the base portion having a thickness greater then a thickness of the tip portion. The tapered fins may have the fin slope as measured from the fin centerline in the range from 1.0 to 1.5 degrees.
For a further understanding of the disclosure, reference will be made to the following detailed description which is to be read in connection with the accompanying drawing, where:
Referring initially to
The heat sink device 20 includes a base platform 26, a plurality of upright members 28, and a plurality of heat transfer fins 30. The base platform 26, the upright members 28 and the heat transfer fins 30 may be formed by extrusion, by casting, or by machining to form an integral one-piece heat sink device 20. The heat sink device 20 may be formed of aluminum, aluminum alloys, copper, copper alloys, or other materials having a high thermal conductivity.
In the depicted embodiment, the base platform 26 has a middle span 32, a right-hand span 34 (to the right of the middle span 32 as viewed in
The base platform 26 has a first surface 38 on one side thereof and a second surface 40 on the opposite side thereof. Upright members 28-1, 28-2, 28-3, 28-4 extend outwardly from the first surface 38 of the base platform 26, which in the embodiments depicted in
Heat transfer fins 30 extend outwardly from the second surface 40 of the base platform 26, which in the embodiments depicted in
In the embodiment depicted in
It is to be understood that in other embodiments, the heat transfer fins 40 may be curved plate fins or wave-like fins extending longitudinally in parallel spaced relationship. The heat transfer fins 30 may have a cross-section form that is rectangular or tapered, as shown in the depicted embodiments, but may instead have a cross-section form that is triangular, trapezoidal, hyperbolic, parabolic, elliptical or other desired cross-section shape. The heat transfer fins 30 may include heat transfer enhancements such as, but not limited to surface roughness, beads, surface bumps or risers, louvers, off-sets, and cut-offs between fins. Any combination of the abovementioned heat transfer enhancement features may be used on the heat sink device 20 disclosed herein.
Referring now to
When disposed within the housing 50, the tips of the heat transfer fins 30 are juxtaposed in substantially abutting relationship with one interior wall of the housing 50, while the end faces of the upright members forming the bounding wall 25 are juxtaposed in substantially abutting relationship with the opposite interior wall of the housing 50. The cooling air flow passes through the channels 48 across and over, and in convective heat exchange relationship with, the heat transfer surface of the heat transfer fins 30. In this manner, heat generated by the power electronics module 22 housed in the chamber 46 is removed by the cooling air flow by means of conductive heat exchange from the cavity 46 and the power electronics module 22 through the base platform 26 to the heat transfer fins 30 and by means of convective heat exchange from the heat transfer fins 30 to the cooling air flow passing through the channels 48. However, the power electronics module 22, being disposed in the cavity 46, remains isolated from the cooling air flow and therefore not exposed to moisture or corrosive elements that might be present in the cooling air flow.
In the depicted embodiment, the cooling air fan 60 is mounted in the cooling air inlet opening 56 and operates to blow ambient air into and through the cooling air flow duct 54 to pass across and over the surfaces of the heat transfer fins 30 and the base platform 26 of the heat sink device 20. To achieve sufficient convective heat transfer between the cooling air flow and the heat transfer fins 30 and the base platform 26 of the heat sink device 20 to ensure cooling of the power electronics module 24 to a temperature below a threshold temperature of 85° C. (185° F.) in accord with the method disclosed herein, the cooling air flow may be passed through the flow channel at an air flow velocity in the range of from 4 to 20 millimeters per second per Watt of heat rejection by the power electronics module 24.
By way of example, tests of a prototype of the heat sink device 20 housing a 300 Watt IGBT and disposed in a cooling air flow duct at or within a distance of one-half the width of the heat sink device downstream of the outlet of the cooling air fan 60. Additionally, the heat transfer fins 30 were tapered fins having a height of 45 millimeters (1.77 inches), a base width of 3 millimeters (0.118 inches) and a tip width of 1.43 millimeters (0.056 inches) on the right-hand and left-hand sections 34, 36 of the base platform 26 and having a height of 70 millimeters (2.76 inches), a base width of 4 millimeters (0.157 inches) and a tip width of 0.56 millimeters (0.022 inches) on the middle section 32 of the base platform 26. The base platform 26 of the tested heat sink device 20 had a thickness of 8 millimeters (0.315 inches) in the middle section 32 and a thickness of 4 millimeters (0.157 inches) in each of the right-hand side and left-hand side sections 34, 36 of the base platform 26. The heat sink device was cast as an integral one-piece heat sink device 20 using an AlSi12 aluminum silicon alloy. The temperature of the 300 W IGBT was maintained below a threshold maximum temperature of 85° C. (185° F.) using a cooling air flow having at inlet temperature of 39° C. (100° F.) passing through the cooling air flow channels at an air flow velocity of in the range of at least 3.0 meters/second (9.8 feet per second) to 8.0 meters per second (26 feet per second) at a fan output cooling air flow rate in the range from 70 to 90 CFM (cubic feet per minute) (2.0 to 2.5 cubic meters per minute).
Various specific non-dimensional geometric ratios have been identified and quantified for facilitating manufacturing and enhancing heat transfer performance of the heat sink device 20 disclosed herein, while achieving a reduction in footprint area, a reduction in material content, and a reduction in cost. The various dimensional parameters referred to in the following paragraphs are shown in
The ratio of the height of the heat transfer fins 30 to the thickness of the base platform 26 from which the fins 30 extend should lie in the range of 2 to 30, inclusive, to facilitate manufacturing.
The ratio of the thickness tp of the base platform 26 from which the fins 30 extend to the nominal fin thickness, which for a fin having a uniform thickness tf and for a fin having a non-uniform thickness is an average thickness (tb−tt)/2, should be in the range from 0.5 to 1.0, inclusive, to ensure adequate conductive heat transfer between the fins 30 and the base platform 26.
For tapered fins, the ratio of the difference between the thickness of the fin base and the thickness of the fin tip (tb−tt) to the fin height hf should be such as to provide a fin slope Ø, as measured from the fin centerline, in the range from 1.0 to 1.5 degrees, inclusive, to facilitate casting of the heat sink device 20.
The ratio of the spacing S between the side walls of neighboring fins 30 at the base of the fins to the thickness of the fins tb at the fin base should be in the range from 2 to 3, inclusive, to facilitate manufacturing.
As noted previously, the heat transfer fins 30 may include heat transfer enhancements such as surface roughness, surface bumps, which includes risers, and fin cutoffs. With respect to surface roughness, the surface roughness enhancement may have a height in the range of 0.38 to 1.52 millimeters (0.015 to 0.06 inches). With respect to fins 30 having surface bumps or risers, see
For wave-like heat transfer fins, see
With the heat sink device 20 as disclosed herein, heat may be removed from the cavity 36 and the power electronics module 24 disclosed within the cavity 36 through primarily conductive heat exchange to the base platform 26 and therethrough to the heat transfer fins 30 and thence by primary convective heat exchange trough the heat transfer fins 30 to the cooling air flow passing through the channels 48 of the heat sink device 20. In this manner, the power electronics module 24 may be cooled without being in direct contact with the cooling air. Thus, the power electronics module 24 will not be exposed to moisture or corrosive elements within the cooling air, typically ambient air, and the potential corrosive effects attendant with such exposure.
The terminology used herein is for the purpose of description, not limitation. Specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as basis for teaching one skilled in the art to employ the present invention. Those skilled in the art will also recognize the equivalents that may be substituted for elements described with reference to the exemplary embodiments disclosed herein without departing from the scope of the present invention.
While the present invention has been particularly shown and described with reference to the exemplary embodiments as illustrated in the drawing, it will be recognized by those skilled in the art that various modifications may be made without departing from the spirit and scope of the invention. Therefore, it is intended that the present disclosure not be limited to the particular embodiment(s) disclosed as, but that the disclosure will include all embodiments falling within the scope of the appended claims.
Reference is made to and this application claims priority from and the benefit of U.S. Provisional Application Ser. No. 61/487,068, filed May 17, 2011, and entitled HEAT SINK FOR COOLING POWER ELECTRONICS, which application is incorporated herein in its entirety by reference.
Filing Document | Filing Date | Country | Kind | 371c Date |
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PCT/US12/33184 | 4/12/2012 | WO | 00 | 11/13/2013 |
Number | Date | Country | |
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61487068 | May 2011 | US |