Abstract:
An improved cooling system for a power supply of a welding or plasma cutting system. The cooling systems includes sections that are divided. One section contains electrical components and remains relatively clean, and does not receive an airflow from a fan. Another section does not contain electrical components and channels a majority of the airflow into and out of the power supply. The section channeling the majority of the airflow shields the section with the electrical components from a majority of the airflow. The method includes step of forming and disposing the structure of the cooling system.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims benefit of priority to U.S. Provisional Patent Application Nos. 60/825,510, 60/825,515, and 60/825,520, all filed Sep. 13, 2006, which are incorporated by reference in there entirety. This application also relates to two co-pending applications identified by Attorney Docket Nos. HYP-078A and HYP-078C. 
     
     FIELD OF THE INVENTION 
       [0002]    The invention generally relates to the field of power supplies used with plasma arc torch systems and processes. More specifically, the invention relates to the cooling system used in a power supply, and the configuration of the components of a power supply. 
       BACKGROUND OF THE INVENTION 
       [0003]    Common welding-type power supplies used in high temperature metal processing systems such as welding or plasma cutting systems generally include a power supply connected by a cable to a torch at which the welding or cutting operation takes place. In manual, hand-operated systems the torch is typically contained in an insulated handle that is held and guided by an operator. In automated systems, the movement of the torch is typically performed using a cutting table that is controlled by a computer using CNC. In both manual and automated systems, the torch is detachably connected to the cable, and the cable is detachably connected to the power supply. Depending on the system performance desired for a particular welding or cutting operation, the system can be assembled from various combinations of power supply, cable, and torch. Common performance factors considered when selecting a power supply include the costs of purchase, operation, and maintenance of the power supply, the ability of power supply to remain within an operational temperature range, the mobility of the power supply, and the environment in which the power supply will be used. 
         [0004]    A significant factor in the selection of a power supply is the cost relating to the purchase, operation, and maintenance of the power supply. The purchase price and repair costs are in part related to the effort required to assemble and disassemble the power supply. Maintenance costs are also increased because the time required for repair is unduly long, as increased repair costs reflect a greater amount of labor, and because of the extended down time during which the power supply is not available for service. The operational costs are also affected by the efficiency of the power supply, which is degraded, for example, when the power supply operates at an excessively elevated temperature. It is therefore desirable that the power supply operate efficiently at low operational cost while also being affordable to purchase and maintain. 
         [0005]    Another factor considered in the selection of a welding-type power supply is the ability of the device to remove heat generated by internal components. Due to the large amounts of power handled by the power supply, internal transformers, resistors, and other heat-generation components raise the overall temperature of the power supply. Excessive heat in the power supply can lead to component damage, reduced efficiency of the system, and the tripping of temperature sensors that limit duty cycle. These conditions represent failures of the power supply because the device is no longer operational until repaired or sufficiently cooled and reset, or limits operating time until components are cooled and reset. Such outages represent lost shop time and adversely affect efficiencies and throughput capacities. 
         [0006]    Many common power supplies utilize a forced-air cooling system to cool internal components. However, existing forced-air cooling systems require a power supply layout in which the heat-generating parts are distributed sufficiently far apart from each other to permit the inflow and circulation of cooling air. The layout of such systems leads to a large power supply size, which in turn limits the mobility of the power supply. Often, the power supply must be transported with other equipment to the worksite or carried by hand, and a large, bulky, or heavy power supply is more difficult to transport. Furthermore, a layout in which internal components are spaced apart to promote circulation leads to more complicated manufacturing and repair procedures, as most internal components must be separately mounted to the power supply framework and hardwired into the device. Such designs lead to extra system costs because of the additional manufacturing and wiring required, and to extra repair costs because of the additional time required to identify and replace failed or defective internal components. Additional costs also result because the complexity of such systems requires additional repair time during which the system is not useable. It is therefore desirable that the power supply be capable of maintaining a sufficiently low operational temperature while minimizing power supply size and having a simplified component layout. 
         [0007]    Yet another factor considered in the selection and design of a power supply is the environment in which the power supply will be used. Welding and cutting operations can be performed in a wide variety of environments and harsh conditions, such as outdoors, in high humidity or rain, and in atmospheres that contain corrosive, conductive, potentially flammable, or other dust-type contaminates. Existing forced air cooling systems impel moisture and contaminated air through the power supply and, due in part to the distribution of heat-generating components in such systems, the entrained moisture and contaminants are distributed throughout the inside of the power supply. Over time, the moisture and contaminants affect and/or accumulate upon component surfaces within the power supply, eventually reducing the ability of those components to remove excessive heat and possibly corroding or otherwise degrading the performance of the components or cause electrical shorting of components. It is therefore desirable that the power supply be capable of operating in a wide variety of environments at operational temperature while minimizing the exposure of internal components to moisture and other environmental contaminants. 
         [0008]    In view of the foregoing, what is needed is a cooling system for a power supply that has low system and operational costs, is capable of maintaining an operational temperature within certain boundaries, has minimal size and a simplified design, and is capable of performing in a variety of environments while minimizing the entry of moisture and contaminants into the power supply. A first object of the invention is to provide a power supply that operates efficiently at low operational cost while also being affordable to purchase and maintain. Another object of the invention is to provide a power supply that is capable of maintaining an operational temperature while simultaneously minimizing power supply size and promoting a simplified component layout. Yet another object of the invention is to provide a power supply capable of operating in a wide variety of environments at reasonable operational temperatures while minimizing the exposure of internal components to moisture and other environmental contaminants. 
       SUMMARY OF THE INVENTION 
       [0009]    In a first aspect of the invention, a cooling system for a power supply can include a heat sink that can have a base and a plurality of fins extending from the base, and each fin can have an outer fin edge. The plurality of fins can form at least one channel between adjacent fins, and the at least one channel can have a central portion and an end portion, and the end portion can correspond to an end of the heat sink. A panel can be disposed along the outer fin edges of the adjacent fins to at least partially enclose the at least one channel, and the panel can extend from the central portion to at least a midpoint of the end portion. A fan can be aligned with the heat sink that can direct a gas flow to the central portion, and at least a portion of the gas flow can exit the at least one channel at the end portion. Embodiments can include a direction of the gas flow to the central portion that can be redirected in a different direction. The direction of the gas flow to the central portion can be at approximately a right angle to a direction of the portion of the gas flow that can exit at the end portion. The fan can direct another gas flow in a direction away from the central portion. At least a portion of the panel can extend to the end of the heat sink. At least a portion of the gas flow can exit from the end of the heat sink. At least one channel can have another end portion and at least a portion of the gas flow can exit the at least one channel at the another end portion. The central portion can be disposed between the end portion and the another end portion. The gas flow to the central portion can be cooler than the gas flows that can exit at the end portions. The central portion can be in an approximate middle section of the power supply. The gas flow can enter a side of the power supply and can exit at another side of the power supply, and the side and another side can be adjacent to each other. A plurality of electrical components can be in thermal contact with the heat sink. The plurality of electrical components can include at least one of a resistor, a silicon power device, or a magnetic device. At least a portion of the gas flow can be constricted in a majority of the at least one channel. 
         [0010]    In a second aspect of the invention, a method of cooling a power supply can include forming a heat sink in the power supply, the heat sink can have a base and a plurality of fins extending from the base and each fin can have an outer fin edge. The plurality of fins can form at least one channel between adjacent fins, and the at least one channel can have a central portion and an end portion that can include an end of the heat sink. A panel can be positioned along the outer fin edges of the adjacent fins that can at least partially enclose the at least one channel, and the panel can extend from the central portion to at least a midpoint of the end portion. A gas flow can be directed via a fan to the central portion, and at least a portion of the gas flow can exit the at least one channel disposed at the end portion. 
         [0011]    In a third aspect of the invention, a cooling system for a power supply can include at least one gas passage that can be enclosed by one or more walls and can extend through the power supply from an approximate middle portion of the power supply to at least one side of the power supply. The at least one gas passage can have a central portion that can be disposed at the middle portion and can have an end portion that can be disposed near the at least one side. A fan can direct a gas flow to a passage that can be located in or formed by the at least one gas passage that can be disposed at the central portion. Gas entering the passage entrance can be directed through the at least one gas passage to an exit passage that can be disposed at the end portion of the at least one gas passage. Embodiments include a direction of the gas flow to the passage entrance that can be redirected in a different direction. A direction of the gas flow to the passage entrance can be at approximately a right angle to a direction of the gas flow that can be directed through the at least one gas passage. The cooling system can have at least two of the at least one gas passages, and the central portion can be disposed between the at least two gas passages. The gas flow to the passage entrances can be cooler than the gas flows that can exit at passage exits. The central portion can be in an approximate middle section of the power supply. The gas flow can enter a side of the power supply and can exit at another side of the power supply, and the side and another side can be adjacent to each other. A plurality of electrical components can be in thermal contact with the one or more walls. The plurality of electrical components can include at least one of a resistor, a silicon power device, or a magnetic device. The at least a portion of the gas flow can be constricted in a majority of the at least one gas passage. 
         [0012]    In a fourth aspect of the invention, a method of cooling a power supply can include forming in the power supply at least one gas passage that can be enclosed by one or more walls and can extend through the power supply from an approximate middle portion of the power supply towards at least one side of the power supply. The at least one gas passage can have a central portion that can be disposed at the middle portion and can have an end portion that can be disposed near the at least one side. A gas flow can be directed to a passage entrance of the at least one gas passage at the central portion. Gas entering the passage entrance can be directed through the at least one gas passage to a passage exit of the at least one gas passage at the end portion. 
         [0013]    In a fifth aspect of the invention, a power supply can include a fan that can direct a gas flow through an inlet port that can be disposed in an inlet side of the power supply. One or more gas outlet ports can be disposed in one or more adjacent sides of the power supply, the one or more adjacent sides can be adjacent to the inlet side, and at least a portion of the gas flow can exit the power supply through the one or more gas outlet ports. A majority of the gas flow can pass through at least one heat sink passage that can be disposed in a heat sink. The at least one heat sink passage can be enclosed by at least one wall within the heat sink for a majority of a length of the at least one heat sink passage. Embodiments include a cooling system in which a majority of the gas flow can enter the gas inlet port and can be redirected in one or more directions that can correspond to the one or more gas outlet ports. A majority of the gas flow can enter the gas inlet port and can be redirected in one or more directions that can be different than an inflow direction that can flow into the gas inlet port. A direction of the gas flow into the gas inlet port can be at approximately a right angle to a direction of the at least a portion of the gas flow that can exit the power supply. The cooling system can have at least two of the at least one heat sink passage, and a portion of the majority of the gas flow can enter each of the at least two heat sink passages at an approximate middle portion of the heat sink that can be disposed between the at least two heat sink passages. The portions of the gas flow that can enter the at least two heat sink passages can be cooler than the portions of the gas flow that can exit the power supply. The gas inlet port can disposed in an approximate middle of the inlet side. The fan can direct the gas flow to a point inside the power supply that can be disposed between two of the one or more adjacent sides of the power supply. A plurality of electrical components can be in thermal contact with the heat sink. The plurality of electrical components can include at least one of a resistor, a silicon power device, or a magnetic device. The gas flow that can pass through the at least one heat sink passage can be constricted by a majority of the at least one heat sink passage. The gas flow can be an airflow. 
         [0014]    In a sixth aspect of the invention, a method of cooling a power supply can include disposing a gas inlet port in an inlet side of the power supply. A gas flow can be directed using a fan through the gas inlet port into the power supply. At least a portion of the gas flow can be directed through and out of the power supply via one or more gas outlet ports in one or more adjacent sides of the power supply. The one or more adjacent sides can be adjacent to the inlet side. A majority of the gas flow can pass through at least one heat sink passage that can be disposed in a heat sink, and the at least one heat sink passage can be enclosed by at least one wall for a majority of a length of the at least one heat sink passage. 
         [0015]    In a seventh aspect of the invention, a cooling system for a power supply can include a first section of the power supply can contain a plurality of electrical components. A second section of the power supply can receive a majority of a gas flow that can be directed into the power supply by a fan. The second section can direct the majority of the gas flow out of the power supply, and the second section can separate the majority of the gas flow from the electrical components. Embodiments include a first section that can be a clean section that can be less exposed than the second section to an environmental contaminant in the gas flow. The second section can be a dirty section that can be more exposed than the first section to an environmental contaminant in the gas flow. A direction of the gas flow that can be received into the second section can be redirected in a different direction. A direction of the gas flow that can be received into the second section can be at approximately a right angle to a direction of the gas flow that can be directed out of the power supply. The fan can direct another gas flow in a direction away from the second section. The second section can direct the majority of the gas flow out of the power supply in at least two directions, and a portion of the majority of the gas flow can be directed in each of the at least two directions. A portion of the second section that can receive the majority of the gas flow can be disposed between portions of the second section that can direct the majority of the gas flow out of the power supply. A gas flow in the portion that can receive the majority of the gas flow can be cooler than gas flows in the portions that can direct the majority of the gas flow out of the power supply. A portion of the second section that can receive the majority of the gas flow can be disposed in an approximate middle section of the power supply. The gas flow can enter a side of the power supply and can exit at another side the power supply, and the side and another side can be adjacent to each other. The second section can be formed to have at least one wall, and a plurality of electrical components can be in thermal contact with the at least one wall. The plurality of electrical components can include at least one of a resistor, a silicon power device, or a magnetic device. A majority of the second section can constrict the majority of the gas flow. 
         [0016]    In an eighth aspect of the invention, a method of cooling a power supply can include forming a first section within the power supply that can contain a plurality of electrical components. A second section can be formed within the power supply that can receive a majority of a gas flow that can be directed by a fan into the power supply, and the second section can direct the majority of the gas flow out of the power supply. The second section can separate the majority of the gas flow from the plurality of electrical components. 
         [0017]    In a ninth aspect of the invention, a cooling system for a power supply can include a section of the power supply that can channel a majority of a gas flow that can be directed by a fan into the power supply through and out of the power supply. The section can shield a plurality of electrical components from the majority of the gas flow. Embodiments include a section that can receive the majority of the gas flow in a direction and that can channel the majority of the gas flow in a different direction. A direction of the gas flow that can be received into the section can be at approximately a right angle to a direction of the gas flow that can be channeled out of the power supply. The fan can direct another gas flow in a direction away from the section. The section can channel the majority of the gas flow out of the power supply in at least two directions, and a portion of the majority of the gas flow can be directed in each of the at least two directions. A portion of the section that can receive the majority of the gas flow can be disposed between portions of the section that can channel the majority of the gas flow out of the power supply. A gas flow in the portion that can receive the majority of the gas flow can be cooler than gas flows in the portions that can channel the majority of the gas flow out of the power supply. A portion of the section that can receive the majority of the gas flow can be disposed in an approximate middle section of the power supply. The gas flow can enter a side of the power supply and a portion of the majority of the gas flow can exit at another side of the power supply, and the side and another side can be adjacent to each other. The section can be formed to have at least one wall, and a plurality of electrical components can be in thermal contact with the at least one wall. The plurality of electrical components can include at least one of a resistor, a silicon power device, or a magnetic device. A majority of the section can constrict the majority of the gas flow. 
         [0018]    In an eleventh aspect of the invention, a method of cooling a power supply can include forming within a power supply a section of the power supply that can be capable of channeling a majority of a gas flow that can be directed into the power supply by a fan through and out of the power supply. The section can shield a plurality of electrical components that can be disposed in the power supply from the majority of the gas flow. 
         [0019]    In a twelfth aspect of the invention, a cooling system for a power supply can include a section that can be disposed within the power supply that can receive a majority of a gas flow that can be directed into the power supply by a fan. The section can direct the majority of the gas flow out of the power supply, and the section can be substantially devoid of electrical components. Embodiments include a section that can receive the majority of the gas flow in a direction and that can direct the majority of the gas flow in a different direction. A direction of the gas flow that can be received into the section can be at approximately a right angle to a direction of the gas flow that can be directed out of the power supply. The fan can direct another gas flow in a direction away from the section. The section can direct the majority of the gas flow out of the power supply in at least two directions, and a portion of the majority of the gas flow can be directed in each of the at least two directions. A portion of the section that can receive the majority of the gas flow can be disposed between portions of the section that can direct the majority of the gas flow out of the power supply. A gas flow in the portion that can receive the majority of the gas flow can be cooler than gas flows in the portions that can direct the majority of the gas flow out of the power supply. A portion of the section that can receive the majority of the gas flow can be disposed in an approximate middle section of the power supply. The gas flow can enter a side of the power supply and a portion of the majority of the gas flow can exit at another side of the power supply, and the side and another side can be adjacent to each other. The section can be formed to have at least one wall, and a plurality of electrical components can be in thermal contact with the at least one wall. The plurality of electrical components can include at least one of a resistor, a silicon power device, or a magnetic device. A majority of the section can constrict the majority of the gas flow. The gas flow can be an airflow. 
         [0020]    In a thirteenth aspect of the invention, a method of cooling a power supply can include forming a section within the power supply that can receive a majority of a gas flow that can be directed into the power supply by a fan. The section can direct the majority of the gas flow out of the power supply, and the section can be substantially devoid of electrical components. 
         [0021]    In a fourteenth aspect of the invention, a method of assembling a power supply can include mounting a plurality of heat-generating components to a single circuit board. The mounted heat-generating components can be thermally connected to a heat sink. Embodiments include mounting at least one of a resistor, a silicon power device, or a magnetic device to the single circuit board. 
         [0022]    In a fifteenth aspect of the invention, a power supply can include a thermally-conductive plate that can have a first surface, a second surface that can be opposed to the first surface, and edges that can be located about a periphery of the plate. A plurality of heat-generating components can be mounted on the first surface of the plate. The plate can be disposed between the plurality of heat-generating components and a wall of an enclosure surrounding the power supply. The plate can be disposed to maintain a gap between the second surface and the wall, and the gap can facilitate a gas flow around an exposed surface area of the plate. Embodiments include a plurality of heat-generating components that can include at least one of the following: an inductor, a transformer, or an electromagnet. The plurality of heat-generating components can include a thermally-conductive electrical polymer, e.g., between the thermally conductive components and the electrically-conductive components. The gas flow can be an airflow. 
         [0023]    In a sixteenth aspect of the invention, a method of assembling a power supply can include positioning in the power supply a thermally-conductive plate that can have a first surface, a second surface that can be opposed to the first surface, and edges that can be located about a periphery of the plate. A plurality of heat-generating components can be mounted on the first surface of the plate. The plate can be disposed between the plurality of heat-generating components and a wall of an enclosure surrounding the power supply. The plate can be positioned to maintain a gap between the second surface and the wall. The gap can facilitate a gas flow around an exposed surface area of the plate. 
         [0024]    In a seventeenth aspect of the invention, a power supply can include a panel that can be positioned in a center location of the power supply. The panel can approximately bisect the power supply relative to a vertical axis that can extend therethrough. A heat sink can be positioned within the power supply and can be mounted to the panel, and the panel and heat sink together can form a mounting structure. A plurality of components can be connected to the mounting structure, and a power supply enclosure an surround the mounting structure. Embodiments include a plurality of components that can include at least one of a carrying handle for the power supply, an inductor, a transformer, an electromagnet, a resistor, a silicon power device, or a magnetic device. The enclosure can include at least two end panels, a base, and a cover. 
         [0025]    In an eighteenth aspect of the invention, a method of assembling a power supply can include positioning a panel at a central location within the power supply. The panel can at least substantially bisect the power supply relative to a vertical axis that can extend therethrough. A heat sink can be mounted to the panel, and the panel and heat sink together can form a mounting structure. A plurality of components can be connected to the mounting structure, and a power supply enclosure can be connected to the mounting structure. 
         [0026]    In a nineteenth aspect of the invention, an electromagnetic component of a power supply can include a core that can have a length with a first end and a second end. A plurality of windings can be disposed around the core, and the first end can include a surface that can be adapted to engage a surface of a heat sink that can be disposed in the power supply, and the core can be thermally connected to the heat sink. Embodiments include a component that can include at least one of the following: an inductor, a transformer, or an electromagnet. The component can include a thermally-conductive electrical polymer. The first end can be formed to have a planar surface that can engage a mating planar surface of the heat sink. The component can abut at least a portion of a circuit board, and the component can be electrically connected to the circuit board. 
     
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0027]    The foregoing discussion will be understood more readily from the following detailed description of the invention, when taken in conjunction with the accompanying drawings, in which: 
           [0028]      FIG. 1  is a perspective view of a power supply configuration with the enclosure, handle, and one end panel removed to provide detail regarding internal components; 
           [0029]      FIG. 2  is an alternative view of  FIG. 1  with the opposite end panel removed; 
           [0030]      FIG. 3  is an exploded view of the power supply configuration of  FIG. 1 ; 
           [0031]      FIG. 4  is an alternative exploded view of  FIG. 3 ; 
           [0032]      FIG. 5  is a view of the power supply enclosure and handle removed from  FIGS. 1-4 ; 
           [0033]      FIG. 6  is a view of the internal components of the power supply, showing an alternative embodiment for the arrangement the heat sink, power board, and components; 
           [0034]      FIG. 7  is a view of the internal components of the power supply, showing an alternative embodiment for the arrangement an extended heat sink, the power board, and components; and 
           [0035]      FIG. 8  is a view of the panel and heat sink assembly of the preferred embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0036]    Reference will now be made in detail to embodiments of the invention, one or more examples of which are illustrated in the figures. Each embodiment described or illustrated herein is presented for purposes of explanation of the invention, and not as a limitation of the invention. For example, features illustrated or described as part of one embodiment can be used with another embodiment to yield still a further embodiment. It is intended that the present invention include these and other modifications and variations as further embodiments. 
         [0037]    By well known methods, a power supply provides power to a welding or plasma cutting system through a cable. As shown in  FIGS. 1-4 , the power supply  10  includes well known connectors  12  that can connect the power supply  10  to the cable (not shown), to a power source such as line voltage (not shown), and to additional hoses (not shown) used to supply one or more gases to the system. 
         [0038]    As shown in  FIGS. 1-5 , the invention includes power supplies in which the exterior of the power supply (ends  14  and cover  16 ) includes ports  18  for the ingress and egress of a cooling gas, which can be air. Air is identified as the gas in this description but it is understood that another gas or a mixture of air and another gas could be used to cool the power supply  10 . An inlet  18   a  provides a port through which air enters the power supply  10 , and outlets  18   b  provide ports through which air can exit the power supply  10 . The inlet  18   a  and outlets  18   b  include louvers partially covering the ports. The power supply  10  can comprise an enclosure including ends  14 , a base  20 , and cover  16 . Extending from the power supply  10  is a handle  22  for carrying the power supply. In an embodiment with a larger power supply, the base  20  may include wheels (not shown) to moveably support the power supply. 
         [0039]      FIGS. 1-2  illustrate an assembled view and  FIGS. 3-4  illustrate an exploded view of the power supply  10  of the preferred embodiment. The power supply  10  includes a fan  24  that draws air into the power supply  10  through the inlet  18   a . Surrounding the fan  24  is a plenum  26  having a generally tubular shape and directing the air flowing through the fan  24  between ports at each end of the plenum  26 . One end of the plenum  26  can flare out to a greater cross sectional dimension, and can abut the inside surface of the inlet  18   a  to receive the air passing through the inlet. The other end of the plenum  26  can extend to abut against a port  27  within a panel  28  disposed against the side of a heat sink  30 . The inlet-facing end of the plenum  26  directs the air entering the plenum into the fan  24 . The heat-sink facing end of the plenum  26  directs the air passing through the fan  24  into the port  27 . As shown in  FIG. 8 , the port  27  can have one or more main ports  27   a  and a slit port  27   b . The main port  27   a  directs a majority of the air passing through the fan  24  to the side of the heat sink  30 . The slit port  27   b  allows a small portion of the air passing through the fan  24  to be directed into an internal compartment  32  of the power supply, away from the heat sink  30 . Preferably, the air entering the internal compartment  32  exits through outlets  18   b  at the ends of the power supply  10 . 
         [0040]    Referring again to  FIGS. 1-4 , the panel  28  generally bisects the power supply  10 , forming a vertical wall extending vertically between the base  20  of the power supply to the top, and horizontally between the ends  14  of the power supply. The port  27  is disposed in approximately the center of the panel  28 , and joins the heat-sink side of the plenum  26  to the side of the heat sink  30 . The port  27  thus provides a passage through which a majority of the air impelled by the fan  24  enters the heat sink  30 . As shown in  FIG. 8 , the panel  28  is formed to have an offset portion  34  conforming to the shape of the heat sink  30 . The offset portion  34  can be shaped to receive at least a portion of the heat sink  30 , thereby promoting the improved air flow characteristics of the invention. Moreover, the offset portion  34  allows both the panel  28  and the heat sink  30  to be centrally disposed in the power supply  10 . The panel  28  is preferably made of a metal or another thermally-conductive material to promote heat dissipation. As illustrated, the panel forms a central support structure for the power supply, providing support for the heat sink and a plurality of components, described in detail below, which can be attached to the combined panel  28  and heat sink  30 . The panel can also connect to and provide support for the base  20 , ends  14 , cover  16 , and handle  22 . 
         [0041]    The illustrated heat sink  30  has a base  36  and fins  38  extending from the base  36 . The heat sink  30  also has a length extending between the ends  14  of the power supply, and the middle of the heat sink  30  is disposed in approximately the middle of the power supply, with the ends of the heat sink  30  disposed in approximately the middle of the ends of the power supply  10 . Between adjacent fins  38 , channels  40  can extend the length of the heat sink  30 . The heat sink is preferably extruded or assembled from a metal, but can also be made of a ceramic or other material capable of transferring heat from the base to the fins. In the preferred embodiment, the heat sink  30  extends the entire length of the power supply  10 , from one end to the other end. However, in an alternative embodiment, the heat sink can extend within only a portion of the power supply, or extend from the middle of the power supply to only one end of the power supply. In some embodiments, the heat sink is comprised of several smaller heat sinks that can be positioned near each other. These can also extend in multiple directions, such as in three directions extending from the middle of the power supply towards both ends and the top of the power supply. As shown in  FIG. 7 , the heat sink can also extend below the plenum  26 . 
         [0042]    In a preferred embodiment, a portion of the offset portion  34  of the panel  28  is disposed against the outer edges of the heat sink fins  38 . The channels  40  between the fins  38  can thus be enclosed to form a series of tubes along the length of the heat sink  30 , with each tube having a rectangular cross-section bounded by walls formed from the base  36 , adjacent fins  38 , and panel  28 . In an alternative embodiment, the offset portion  34  of the panel  28  can be formed to abut the sides or edges of only the outermost fins  38   a  of the heat sink  30  without abutting the internal fins disposed inside the heat sink, thus forming a single tube bounded by walls formed from the entire heat sink base  36 , the outermost fins  38   a , and the panel  28 . In such embodiments, the internal fins of the heat sink do not form a part of a wall of the tube. In yet another alternative embodiment (not shown), the heat sink can comprise two heat sinks with fin edges abutting each other to form one or more tubes bounded by walls that are formed from the bases and fins of each heat sink, without the need to employ a panel. In some embodiments, the panel  28  is disposed along the heat sink  30  from the middle of the heat sink to the ends of the heat sink, forming in each tube an entrance port  42  in the middle of the heat sink and an exit port  44  at the end of the heat sink, as illustrated in  FIG. 8 . 
         [0043]    The majority of the air entering the power supply  10  and impelled by the fan  24  can enter the side of the heat sink  30  through the main port  27   a . A small portion of the air passes through the slit port  27   b . In a preferred embodiment, the air entering the heat sink  30  is directed in another direction after entering the heat sink, and is made to move in a new direction at approximately a right angle to the direction of the air passing through the fan, e.g., as illustrated in  FIG. 8 . In an alternative embodiment (not shown), the air can be directed to move is a different direction that is at an acute angle, an obtuse angle, or both, compared to the direction of the air passing through the fan. 
         [0044]    The air entering the heat sink  30  can be directed by each tube to the end of the tube at the end of the heat sink. As illustrated, the exit port  44  of each passage abuts the outlets  18   b  of the power supply and vents the majority of the air impelled by the fan  24  to the outside environment. A majority of the air flowing through the power supply thus contacts only the plenum  26 , fan  24 , and the inside of each tube, without contacting any electrical components contained within the power supply  10 . Furthermore, most of the moisture and/or contaminants entering the power supply with the air being supplied through the inlet port  18   a  is vented out of the power supply without contacting any electrical components. In this embodiment, this moisture and contaminants have contact with no more than the plenum  26 , fan  24 , panel  28 , and heat sink  30 . The passages formed in the heat sink  30  can at least partially restrict the air passing through the heat sink, causing a pressure drop and a resultant increase in air flow velocity. The cooling mechanism of the heat sink can thus be enhanced by the increased flow of air through the heat sink, thereby permitting a greater cooling effect than is achieved with a heat sink that does not have a panel  28  that forms passages with heat sink channels  40 . The improved cooling effect also permits a denser, more compact arrangement of components within the power supply  10  because heat-generating parts can be positioned more closely to the centrally disposed heat sink  30 . 
         [0045]    The power supply can include a plurality of electrical components. As shown in  FIGS. 3 and 4 , these components can include an input bridge  46 , a PFC module  48 , a flyback transformer  50 , an inverter module  52 , an output snubber resistor  54 , and/or an output module  56 . These components can also include a resistor, a silicon power device, and/or a magnetic device. Preferably, these electrical components are physically mounted to and in electrical communication with a single or common power board  58 , thereby forming a power board assembly  60 . The power board assembly  60  can be preassembled before installation in the power supply  10 . Due to the direct connection with the power board  58 , the electrical components  46 - 56  can be electrically connected to the power supply  10  without wires, thus simplifying the design by the elimination of this wiring. Assembly and repair costs are also minimized by reducing the time required to connect each of these components to the power board, as compared to previous power supply designs. As shown in  FIG. 4 , at least some of the components of the power board assembly  60  include surfaces  46   a ,  48   a ,  52   a , and  56   a  facing the heat sink  30  that are planarized to allow direct contact with the base  36  of the heat sink  30 . The planarized surfaces  46   a ,  48   a ,  52   a , and  56   a  can abut the planar base  36  of the heat sink  30 , establishing direct thermal contact, thereby using direct conductive heat transfer with the heat sink  30  to cool the component and the power board assembly  60 . In an assembly or repair procedure, the preassembled power board assembly  60  can be connected as a unitary piece to the heat sink  30 . In an alternative embodiment (not shown), the power board assembly can be composed of two or more boards electrically connected together to form an operable single board. In a preferred embodiment, e.g., as shown in  FIGS. 1 and 2 , the power board assembly  60  is disposed in a section  62  of the power supply  10  that is physically separated and shielded from, and not exposed to, the air passing through the fan  24  or heat sink  30 , or to the air that enters through the inlet  18   a.    
         [0046]    By locating at least some of the electrical components in portions of the power supply that are separated and/or shielded from the airflow impelled by the fan  24 , the components can be cooled indirectly by the airflow, by direct thermal conduction through the heat sink  30 , and can be protected from any moisture or contaminants entrained in the cooling air flow. Accordingly, the power supply  10  includes a clean area  62  that is not exposed to the airflow entering the power supply  10 . Thus, a clean section of the internal compartment  32  is not exposed to the air passing through the heat sink  30 , and a dirty section inside heat sink  30  is exposed to the majority of the airflow passing through the power supply. In the illustrated embodiment, no electrical components (other than the fan  24 ) are located in the portion of the power supply that is exposed to the majority of the airflow that passes through the power supply. In another embodiment (not shown), the clean section of the internal compartment  32  can include minor electrical components, such as a temperature sensor or a air speed sensor. 
         [0047]    The power supply  10  can also include a plate  64  to which are mounted the PFC inductor  66 , the power transformer  68 , and the output inductor  70  which forms a coil assembly  72 . The plate  64  can be made of metal or of a heat-conductive material. Preferably, the coil assembly  72  is preassembled as a single unit that is installed in the internal compartment of the power supply. The coil assembly  72  can be connected to the bottom portion of the panel  28 . As illustrated, the plate  64  of the coil assembly  72  is also connected to the inside surface of the power supply base  20 , and is separated from the inside surface of the base  20  by a gap  74 . A feature of this design is that the small portion of air passing through the slit port  27   b  circulates around the compartment  32  and provides cooling to the surfaces of the coil assembly  72 . 
         [0048]    As shown in  FIG. 6 , in another embodiment of the invention, each of the components  66 ,  68 , and  70  include, e.g., a core  76  and windings  78  to form an electromagnet structure. The core  76  is constructed of a ferromagnetic material or of another magnetically permeable material, with the core  76  extending from the electromagnetic structure to form two ends  80   a ,  80   b . The core  76  is preferably composed of a powder material mixed with a thermally-conductive binder, which is formed into a final shape with a mould. The powder material can be a Powder Iron Type made by Micrometals, Inc. of Anaheim, Calif., or Kool Mn made by Magnetic, Inc. of Pittsburgh, Pa. The thermally-conductive binder enhances the conduction of thermal energy away from the core, and is preferably a polymer such as CoolPoly® D-Series Thermally Conductive Plastic made by Cool Polymers, Inc. of Warwick, R.I. 
         [0049]    One end  80   a  of the core  76  can be formed to have a planar surface  82 , and is preferably disposed to have direct thermal contact to a planar surface of the heat sink  84 . In yet another embodiment (not shown), the components  66 ,  68 , and  70  are disposed to contact the power board assembly  60  and to be electrically connected directly to the power board  58 , thereby eliminating the need for wires for these components. 
         [0050]    While the invention has been particularly shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention as defined by the appended claims.