Abstract:
A heat sink apparatus for use with a liquid refrigerant that tends to generate gas during the cooling process wherein at least some of the gas tends to accumulate on the internal surfaces of heat sink liquid channels forming gaseous pockets that in turn cause surface hot spots, the apparatus for minimizing the surface host spots and comprising a first sink member having first and second substantially oppositely facing surfaces, the second surface for receiving at least one heat generating component, a second sink member having at least a first surface, the first surface of the second sink member secured to the first surface of the first sink member, the first surface of one of the sink members forming a cavity extending between first and second cavity ends and including a cavity surface, the first side of the other of the sink members including a cover surface that substantially covers the cavity and substantially oppositely faces the cavity surface so as to form a channel, at least one of the cavity surface and the cover surface forming a plurality of protuberances between the first and second cavity ends that extend into the cavity, the protuberances increasing turbidity of the liquid flowing therethrough such that channel surface air pockets are substantially eliminated, at least one of the first and second sink members forming an inlet at the first end of the channel and at least one of the first and second sink members forming an outlet at the second end of the channel.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS  
         [0001]    Not applicable.  
         STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT  
         [0002]    Not applicable.  
         BACKGROUND OF THE INVENTION  
         [0003]    The field of the invention is power converters and more specifically converter configurations including heat sinks that reduce the overall space required to accommodate the configurations.  
           [0004]    It is well known that variable speed drives of the type used to control industrial electric motors include numerous electronic components. Among the various electronic components used in typical variable-speed drives, all generate heat to a varying degree during operation. Typically, high-power switching devices such as IGBTs, diodes, SCRs and the like as well as storage devices such as capacitors are responsible for generating most of the heat in a variable-speed drive. It is for this reason, therefore, that most variable-speed drives include a heat sink(s) upon which the power switching devices are mounted. The heat sink(s) conducts potentially damaging heat from assembly components.  
           [0005]    Selecting the size and design of a heat sink for a particular variable speed drive is somewhat of a challenge. First, a designer must be aware of the overall characteristics of the motor and drive pair. Second, the designer must understand the industrial application in which the motor and drive pair will be used, including the continuous and peak demands that will likely be placed on the motor and drive by the load. Third, the designer must accommodate, in the design, certain unexpected conditions that would deleteriously affect the heat transfer capability of the heat sink such as unexpectedly high ambient temperatures, physical damage to the heat sink such as mechanical damage, or a build up of a debris layer, as examples. Fourth, the heat sink(s) must be physically dimensioned so as to fit into the space allotted per customer requirements, cabinet or enclosure size, or the like.  
           [0006]    In the past, air-cooled heat conducting plates were used to transfer thermal energy from electronic parts to the ambient air. These were passive heat-transfer devices and were generally formed of a light-weight aluminum extrusion including a set of fins. As a general rule, heat transfer effectiveness is based on the temperature differential between the power devices and the ambient air temperature. Of course, in order to provide adequate heat conduction, heat sinks of this type oftentimes are necessarily large and, therefore, bulky and expensive. If high ambient conditions exist, the heat sink becomes ineffective or useless as heat removal cannot be accomplished regardless of the size of the heat sink. If the variable speed drive was in an enclosed space the heat removed from the drive would need to be exhausted or conditioned for recirculation.  
           [0007]    By forcing air over fins defined on the heat-conducting plate (e.g., an aluminum extrusion), improved cooling efficiency can be realized. Large blower motors are often used for this purpose. However, as the fins defined in the aluminum extrusions become dirty or corroded during use, the heat sinks become less effective or useless altogether. Blower motors cannot be used in environments where air cleanliness would clog filtration. Therefore, air conditioning equipment is often added to internally circulate and cool the air that is passed over the heat sink fins.  
           [0008]    Liquid cooled heat sinks or cold plates have also been used for some applications but with limited success. Generally, a liquid cooled heat sink includes a series of chambers or channels that are formed internally within a sink body member that is formed of material (e.g., copper or aluminum) that readily conducts heat. The body member includes at least one mounting surface for receiving heat generating devices. The channels are typically configured so that at least one channel section is formed adjacent each surface segment to which a heat generating device is mounted—typical channel configurations are serpentine. A coolant liquid is pumped through the channels from one or more inlet ports to one or more outlet ports to cool the sink member and hence conduct heat away form the heat generating devices.  
           [0009]    The industry has developed several ways in which to manufacture liquid cooled heat sinks and, each of the different ways to manufacture has different costs associated therewith. For instance, a liquid cooled sink can be constructed by forming a desired serpentine copper conduit path for liquid flow, placing the serpentine conduit construct within a sink mold, pouring molten liquid aluminum into the mold and allowing the molten aluminum to cool. While this manufacturing process has been used successfully, liquid molding processes are very difficult to control and the incidences of imperfect and or non-functioning product have been relatively high.  
           [0010]    One other sink manufacturing process that has proven useful includes cutting a at least one channel out of a sink body member, hermetically sealing (e.g., vacuum brazing) a cover member to the body member to cover the channel and then forming an inlet and an outlet that open into opposite ends of the channel. This two part sealing process is much less expensive than the conduit-molten process described above.  
           [0011]    When designing any liquid cooled heat sink several factors have to be considered including heat dissipating effectiveness, volume required to accommodate a resulting converter, and cost. With respect to heat dissipation, in the case of a power conversion assembly, there are typically several different heat generating devices that are similarly constructed and that operate in a similar fashion to convert power. For instance, as well known in the controls arts, an AC to DC rectifier typically includes a plurality of power switching devices that are arranged to form a bridge assembly. In the case of a three phase supply and load, the bridge assembly includes three phases, a separate switching phase for each of the three supply and load phases. Here, an exemplary phase may include first and second power switching devices linked at a common node to an associated supply line where the other terminals of the first and second switches are linked to positive and negative DC busses, respectively. A controller is configured to control all of the three phases of the bridge together to convert the three phase AC supply voltage to a DC potential across the positive and negative DC busses.  
           [0012]    In a similar fashion, a three phase inverter assembly typically includes three separate phases that link positive and negative DC busses to three load supply lines. In the case of an inverter, each phase typically includes first and second power switching devices that are linked in series between the positive and negative DC busses with the common node between the first and second inverter switches linked to an associated phase of the load. Where the supply and load voltages are large, some rectifier/inverter converter assemblies may include several three phase bridges linked together thereby reducing the load handling of each switching device.  
           [0013]    In the case of a rectifier-inverter conversion assembly, a drive circuit is provided that controls all of the switching devices together to create desired three phase output voltages to drive a load linked thereto. In this case, it is imperative that the switching devices operate in characteristic and substantially similar ways to simplify what is, by its very nature, an already complex switching scheme. For this reason, converter designers typically select switching devices having known operating characteristics to configure their conversion assemblies.  
           [0014]    Nevertheless, as also well known, most switching devices have operating characteristics that are, at least in part, affected by the environments in which the devices operate. Specifically, for the purposes of the present invention, it should be appreciated that switching device operating characteristics change as a function of temperature. For instance, an internal switch resistance has been known to change as a function of temperature which in turn affects the voltage drop across the switch. While each voltage drop change that occurs may seem insignificant, because rectifier and inverter switches are typically turned on and off very rapidly, the affect of changing device drop has been shown to be appreciable.  
           [0015]    The problems associated with voltage drop variance are compounded where similar switching devices are operated at different temperatures and is especially acute where control schemes operate to simultaneously control all three conversion assembly phases together to generate load voltages. Thus, for instance, where one switching device is several degrees hotter than another switching device, the result may be unbalanced phase voltages and hence imperfect load control (e.g., non-smooth motor rotation) which increases overall system wear and can cause system damage over time.  
           [0016]    For this reason, one challenge when designing a heat sink for use with a converter assembly has been to provide essentially identical heat dissipating capacity to each converter switching device so that device temperatures are essentially identical during system operation. The problem here is that coolant temperature rises as the coolant absorbs heat along its path through a sink member so that power switching devices relatively near an inlet port along a serpentine coolant path are cooled to a greater degree than switching devices down stream from the inlet port. One solution that reduces the heat dissipating capacity differential between similar switching devices has been to provide a heat sink where the spacing between a cooling liquid inlet and each of the sink surfaces to which switching devices are mounted is similar. For instance, where a configuration includes twenty four power switching devices, instead of mounting the switching devices to the sink in a pattern that tracks a single serpentine cooling conduit path, the switching devices may be mounted on sink member mounting surface to form six rows of four switching devices each where each of the six rows is fed by a separate one of six liquid coolant inlet ports—here a manifold may serve each of the six inlet ports (see generally FIG. 23 in U.S. Pat. No. 6,031,751 (hereinafter “the &#39;751 patent”) entitled “Small Volume Heat Sink/Electronic Assembly” which issued on Feb. 29, 2000 and which is incorporated herein by reference). Thus, in this case, coolant from each of the six inlet ports passes by four separate heat generating devices and device cooling will be relatively more uniform. This solution to reduce the device temperature differential will be referred to hereinafter as a matrix spacing solution.  
           [0017]    One other solution that reduces the heat dissipating capacity differential between switching devices mounted to a sink member has been to provide a serpentine path that passes by each heat generating device more than once so that the overall cooling affect of devices is similar. For instance, assume twelve switching devices are mounted to a sink member mounting surface to form two rows of six devices each and that a single serpentine path is configured to include a first linear run that passes adjacent the first row of devices, a first 180 degree turn, a second linear run that passes adjacent the second row of devices, a second 180 degree turn, a third linear run that again passes adjacent the second row of devices, a third 180 degree turn and a fourth linear run that passes a second time by the first row of devices to an outlet.  
           [0018]    Here, in theory, the first linear run should include the coolest coolant, the second linear run should include the second coolest coolant and so on so that the coolant temperatures through the first and fourth linear runs (i.e., adjacent the devices in the first row) should average and the coolant temperatures though the second and third linear runs (i.e., adjacent the devices in the second row) should also average and the two average temperatures should be similar (see generally FIG. 2 in the &#39;751 patent). This solution to reduce the device temperature differential will be referred to hereinafter as an averaging solution.  
           [0019]    While the averaging solution and the matrix spacing solution work in theory, in reality, each of these solutions have had some problems regarding temperature differential. With respect to the matrix spacing solution, in the example above, the fourth device along each of the six separate coolant paths is warmer than the first device along the same path as liquid passing by the first three devices along the path heats up when heat is absorbed along the path. Thus, while better than sinks that align devices along a single serpentine cooling conduit path, the matrix solution still results in a temperature differential.  
           [0020]    With respect to the averaging solution, it has been determined that, despite multi-pass designs, at least some temperature differential still exists between devices spaced at different locations along the coolant conduit path. In addition, in some cases, cooling capacity may vary over the heat dissipating surface of each heat generating device. This intra-device dissipating differential may occur as a multi pass path necessarily requires that the coolest pass (i.e., the first pass by a device) be positioned along one side of a dissipating surface so that another one or more passes that include relatively warmer coolant can be positioned along the other side of the dissipating surface.  
           [0021]    With respect to volume (i.e., the second factor above to consider when designing a heat sink), as with most electronics designs, all other things being equal, smaller is typically considered better. Thus, some prior converter configurations have provided sink members that either facilitate stacking of relatively short devices adjacent elongated devices (see FIG. 19 in the &#39;751 patent) or, in the alternative, aligning similar dimensions of different devices (see FIG. 13 in the &#39;751 patent).  
           [0022]    For instance, the &#39;751 patent recognizes that, in addition to power switching devices, converter configuration capacitors also often generate excessive heat that should be dissipated to ensure proper operation. The &#39;751 patent also recognizes that capacitors typically have a length dimension perpendicular to their heat dissipating surface that is much longer than the thickness dimensions of typical switching devices perpendicular to the device dissipating surfaces and that the switching devices typically have a length dimension that is similar to the capacitor length dimension. In this case, in one embodiment, the &#39;751 patent recognizes that overall converter configuration size can be reduced by providing an L shaped sink member having two legs that form a 90° angle, mounting the capacitors to an inside surface of one of the legs and within the space defined by the two leg members and mounting the switching devices to the outside surface of the other of the leg members thereby aligning the similar capacitor and device length dimensions.  
           [0023]    With respect to cost, unfortunately, where an L shaped heat sink member or, for that matter, where a sink member having sections that reside along other than a single plane is required to stack or align capacitors with switching devices, the relatively inexpensive two part sealing process described above becomes much more difficult to use. This is because the two part sealing process generally includes vacuum sealing a flat cover member over a channel forming body member, When the channel must reside in more than one plane and requires a more complex cover member, tolerances required to provide a suitable cover member would be extremely difficult to meet and the sealing process would be difficult to perform effectively.  
           [0024]    Thus, where the sink member must reside in two or more planes to facilitate stacking and/or aligning, the more expensive molten-conduit process would likely be employed where the conduit is formed into the desired channel shape and molten aluminum or the like is poured into a mold there around. For this reason prior stacking and aligning configurations have proven to be relatively expensive to manufacture and often are not suitable given cost constraints.  
           [0025]    Also, with respect to cost, often the last converter design consideration is how system components will be electrically linked together to form a converter topology. One particularly advantageous and robust type of linking assembly is referred to generally as a laminated bus bar. As its label implies, a laminated bus bar typically includes a plurality of metallic sheets of laminate that are layered together with insulators between adjacent laminate sheets. Vias are formed within the laminated assembly where links are to be made to capacitor and switching device terminals. The vias automatically link the devices and capacitors up in a desired fashion to provide an intended converter topology (e.g., rectifier, inverter, rectifier-inverter, etc.).  
           [0026]    Laminated bus bar cost is generally a function of the amount of material required to construct the bus, the number of laminate layers required to support a configuration and the overall complexity of the required laminate member where minimal material, minimal layers and minimal contours (i.e., bends in the laminates) are all advantageous. Unfortunately, providing a configuration that uses minimal laminate material, requires minimal layering and restricts the laminate to a single plane is extremely difficult given the sink member configurations required to minimize overall configuration size and provide essentially uniform heat dissipating capacity to all switching devices mounted to the sink. For example, where devices are arranged in rows and columns to provide similar distances between channel inlets and devices down stream therefrom, typically a large number of laminate layers and a correspondingly complex labyrinth of vias are required to link components together. As another instance, where switching device lengths are aligned with similarly dimensioned capacitor lengths the lamination bus typically requires one or, more often, several bends to accommodate connection terminals that reside in disparate planes. In either of these two cases (i.e., many layers or several laminate bends) the amount of material required to configure a laminated bus bar can be excessive and hence unsuitable for certain applications.  
           [0027]    Yet one other cost consideration related to converter configurations has to do with component versatility or the ability to use converter components in more than one converter configuration. Component versatility is particularly important with respect to the more expensive component types such as, for example, the heat sink assembly, the laminated bus bar, etc. In this regard, overall system costs can be reduced by designing sinks and laminated bus bars that can be used with various device and capacitor types. For instance, assume that a first converter configuration includes a first type of switching device, a first type of capacitor, a first type of sink member and a first type of laminate bar. Also assume that the sink, devices and a capacitors are dimensioned such that when the capacitors and devices are mounted to the sink, the capacitors connection terminals are on the same plane as the device connection terminals. Here, the first laminate bus bar type can be planar and hence relatively.  
           [0028]    Next assume that a designer wants to swap out a second capacitor type for the first type in the configuration where the second capacitor type has a thickness between its dissipating surface and its connection terminals that is different than a similarly measures thickness of the first capacitor type. In this case, when the capacitors are swapped, the capacitor and device terminals will no longer reside within the same plane and a different, perhaps custom designed, laminate will be required to accommodate the change. In the alternative, the sink design may be altered to accommodate the change in device and capacitor terminal planes although this solution would be relatively expensive. Similar problems occur when different switching devices are swapped into configurations.  
           [0029]    Thus, it would be advantageous to have a heat sink assembly that is relatively inexpensive to manufacture and yet provides substantially similar heat dissipating capacity to all devices mounted thereto. In addition, it would be advantageous if a sink assembly of the above kind could be used with a simplified laminate design and be used to configure relatively compact converter assemblies. Moreover, it would be advantageous if the sink assembly could be versatile and hence used with other converter components that have many different dimensions.  
         BRIEF SUMMARY OF THE INVENTION  
         [0030]    It has been recognized that relatively compact and inexpensive converter configurations can be configured by using an elongated liquid cooled heat sink to cool power switching devices. More specifically, it has been recognized that, where switching devices are mounted in a single row to a sink member mounting surface, the sink can be used to configure minimal volume converter configurations. In at least one embodiment of the invention, the sink mounting surface has a width dimension that is substantially similar to a width dimension of switching devices to be mounted thereto with the device width dimensions aligned with the mounting surface width dimension. This single row limitation has several configuration advantages described below.  
           [0031]    It has also been recognized that, with certain types of refrigerant, the cooling capacity differential along a cooling channel appears to be exacerbated along the channel length. For instance, the cooling capacity differential appears to be relatively pronounced in the case of two phase refrigerants such as R-134a and R-123. As the label implies, two phase refrigerants change from a liquid to a gas when heat is absorbed and hence, generally, absorb a greater amount of heat, due to the endothermic nature of the phase change, than conventional single-phase liquid refrigerants such as water -hence two phase refrigerants are generally preferred in high efficiency heat sinks.  
           [0032]    Moreover, it has been recognized that, unfortunately, as two-phase refrigerants absorb heat and change phase from liquid to gas, vapor bubbles are formed within the liquid that accumulate on the internal surfaces of the heat sink and form gas pockets. The gas pockets on the surface of the channel block refrigerant from contacting the channel surface and hinder device heat absorption by the refrigerant. Thus, the channel surfaces on which gas pockets form end up becoming hot spots on the channel surfaces and the temperatures of devices attached adjacent thereto rise.  
           [0033]    Because the vapor bubbles are formed by heat absorption and because coolant relatively further down stream from an inlet is warmer than coolant more proximate the inlet, relatively more vapor bubbles are formed down stream from the inlet than proximate the inlet thereby causing more gas pockets to form down stream which increases the temperature differential along the channel length. Thus, it has been determined that, while coolant temperature accounts for some of the temperature differential along a coolant channel length, much of the temperature differential is actually due to different amounts of gas accumulating along different sections of the channel - the gas having an insulating effect between the channel surfaces and the coolant passing thereby. Based on these realizations it should be appreciated that the temperature differential problem is exacerbated where sink channels are extended.  
           [0034]    According to several embodiments of the invention, protuberances of a character, quantity and size that increase turbulence within sink channels to a point where the turbulence either prohibits gas pockets from forming on the channel surfaces or dislodges or breaks up gas pockets that form on the channel surfaces, are provided on at least one of the channel surfaces. It has been found that when such protuberances are provided within a channel, the channel can have an extended length without causing excessive temperature differentials there along. More specifically, it has been determined that the channel length can, in at least one embodiment, extend substantially along an entire sink length where the sink, as indicated above, has a length to accommodate a single row of switching devices. For instance, where a converter configuration includes twenty four switching devices, the twenty four devices can be arranged in a single row along the sink member mounting surface where the channel extends along substantially the entire sink length from an inlet to an outlet.  
           [0035]    It has also been determine that, in at least some embodiments of the invention, the sink member can be juxtaposed so that the channel inlet is below the channel outlet and, more specifically, so that the channel inlet is directly vertically below the channel outlet. Here, dislodged or broken up gas pockets, being lighter than the refrigerant, are aided by buoyancy in their movement toward the outlet at the top of the sink channel.  
           [0036]    By providing an elongated sink-device assembly including devices mounted in a single row to an elongated sink member, overall converter cost can be reduced. In this regard, the single channel sink member can be manufactured using the two piece sealing method described above where the channel is bore out of a body member, a cover member is hermetically sealed over the channel and inlet and outlet ports that open into the channel are formed.  
           [0037]    In addition, cost is reduced with the inventive elongated sink-device assembly as a simplified laminated bus bar can be used with the sink-device assembly. In this regard, where capacitors are juxtaposed to one side of the switching devices and with capacitor terminals and device terminals positioned within a common connection plane, the distances between capacitor terminals and the device terminals that the capacitor terminals are to be linked to are reduced appreciably so that less material is required to make terminal connections. Moreover, because capacitor terminals and the device terminals to which the capacitor terminals are to be linked may be positioned proximate each other, none of the laminates have to pass over other devices disposed intermediate the connecting terminals and therefore simpler laminate and associated via designs can be employed that include relatively small numbers (e.g., 3) of laminate layers.  
           [0038]    Consistent with the above teachings, at least one embodiment of the invention includes a heat sink apparatus for use with a liquid refrigerant that tends to generate gas during the cooling process wherein at least some of the gas tends to accumulate on the internal surfaces of heat sink liquid channels forming gaseous pockets that in turn cause surface hot spots, the apparatus for minimizing the surface host spots and comprising a first sink member having first and second substantially oppositely facing surfaces, the second surface for receiving at least one heat generating component, a second sink member having at least a first surface, the first surface of the second sink member secured to the first surface of the first sink member, the first surface of one of the sink members forming a cavity extending between first and second cavity ends and including a cavity surface, the first side of the other of the sink members including a cover surface that substantially covers the cavity and substantially oppositely faces the cavity surface so as to form a channel, at least one of the cavity surface and the cover surface forming a plurality of protuberances between the first and second cavity ends that extend into the cavity, the protuberances increasing turbidity of the liquid flowing therethrough such that channel surface air pockets are substantially eliminated, at least one of the first and second sink members forming an inlet at the first end of the channel; and at least one of the first and second sink members forming an outlet at the second end of the channel.  
           [0039]    In some embodiments the first sink member forms the cavity. In some embodiments the first sink member also forms the protuberances. In at least some embodiments the cavity includes a substantially elongated cavity and the protuberances are formed substantially along the entire length of the cavity. In more specific embodiments the channel is a first channel and wherein at least one of the first and second sink members forms a channel divider member that extends into the cavity substantially along the entire length of the cavity so that the cavity also forms a second channel that is substantially parallel to the first channel, the first sink member forming protuberances along the lengths of each of the first and second channels.  
           [0040]    The first sink member may form the channel divider. In addition, the protuberances may include first and second protuberance sets, the first protuberance set includes protuberances arranged in a line substantially along the center of the first channel and the second protuberance set includes protuberances arranged in a line substantially along the center of the second channel. Here, the protuberances may be separated by spaces therebetween and the protuberances are equi-spaced along the channel lengths. The dimension between the first surface of the first sink member and the channel surface may be a channel depth and each of the protuberances and the divider member may substantially extend the channel depth from the channel surface.  
           [0041]    The first sink member may also forms a manifold that links the inlet to each of the first and second channels. Here, the manifold may include a receiving chamber and restricted first and second nozzle passages, the inlet may open into the receiving chamber and the first and second nozzles may separately link the receiving chamber to the first and second channels, respectively. More specifically, the receiving chamber may have a cross sectional dimension that is greater than the cross sectional dimensions of each of the first and second nozzle passageways.  
           [0042]    In one aspect the receiving chamber may have a cross sectional dimension that is greater than the combined cross sectional dimensions of the first and second nozzle passageways. In addition, the cross sectional dimensions of the first and second channels may be greater than the cross sectional areas of the first and second nozzle passageways, respectively.  
           [0043]    In several embodiments the divider member terminates before the outlet end of the cavity so that the outlet ends of the first and second channels are linked. In several embodiments the second surface has a width dimension that is similar to a width dimension of the devices to be mounted thereto and has a length dimension substantially parallel to a length dimension of the channels, the length dimension of the second surface substantially perpendicular to the width dimension of the second surface.  
           [0044]    In some embodiments the sink is to be used with devices that have a heat generating footprint, the footprint having a footprint width, the channels together having a channel width dimension that is similar to the footprint width.  
           [0045]    Some embodiments of the invention also include a heat sink apparatus for use with a liquid refrigerant that tends to generate gas during the cooling process wherein at least some of the gas tends to accumulate on the internal surfaces of heat sink liquid channels forming gaseous pockets that in turn cause surface hot spots, the apparatus for minimizing the surface host spots and comprising a sink member having a receiving surface for receiving at least one heat generating component, the sink member internally forming an elongated channel that extends from an inlet end to an outlet end and forming an inlet and an outlet that open into the inlet and outlet ends, respectively, the channel including at least first and second oppositely facing surfaces and forming a plurality of protuberances between the first and second channel ends that extend into the channel, the protuberances increasing turbidity of the liquid flowing therethrough such that channel surface air pockets are substantially eliminated.  
           [0046]    Moreover, at least some embodiments of the invention include a heat sink apparatus for use with a liquid refrigerant that tends to generate gas during the cooling process wherein at least some of the gas tends to accumulate on the internal surfaces of heat sink liquid channels forming gaseous pockets that in turn cause surface hot spots, the apparatus for minimizing the surface host spots and comprising a body member having first and second substantially oppositely facing surfaces, the first surface forming an elongated cavity that extends from an inlet end to an outlet end, forming a first divider member that extends substantially along the length of the cavity and forming second and third divider members juxtaposed on opposite sides of the first divider member such that the divider members separate the cavity into four substantially parallel channels, the second and third divider members forming openings that facilitate passage between adjacent channels, the second surface for receiving at least one heat generating component, a cover member having a first surface secured to the first surface of the body member such that the first surface substantially covers the first and second channels and such that distal ends of each of the divider members contacts the first surface of the cover member, the cover member forming an inlet and an outlet that open into the inlet and outlet ends of the cavity, respectively and a liquid refrigerant source linked to the inlet end of the sink for providing liquid refrigerant thereto.  
           [0047]    These and other objects, advantages and aspects of the invention will become apparent from the following description. In the description, reference is made to the accompanying drawings which form a part hereof, and in which there is shown a preferred embodiment of the invention. Such embodiment does not necessarily represent the full scope of the invention and reference is made therefor, to the claims herein for interpreting the scope of the invention. 
       
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS  
       [0048]    [0048]FIG. 1 a  is a schematic diagram of a rectifier configuration and corresponding controller while FIG. 1 b  is a schematic diagram of an inverter configuration;  
         [0049]    [0049]FIG. 2 is an exploded perspective view of a converter assembly according to one embodiment of the present invention;  
         [0050]    [0050]FIG. 3 is an exploded perspective view of the heat sink member and switch packages of FIG. 2;  
         [0051]    [0051]FIG. 4 is a side plan view of an assembled configuration consistent with FIG. 2;  
         [0052]    [0052]FIG. 5 is a bottom plan view of the conversion configuration of FIG. 4;  
         [0053]    [0053]FIG. 6 is a plan view of the body member of the heat sink member of FIG. 3 and, in particular, showing the surface of the body member in which a coolant channel is formed;  
         [0054]    [0054]FIG. 7 is similar to FIG. 6, albeit illustrating a second embodiment of the body member;  
         [0055]    [0055]FIG. 8 is similar to FIG. 6, albeit illustrating yet one other embodiment of the body member; and  
         [0056]    [0056]FIG. 9 is a flow chart according to one aspect of the present invention. 
     
    
     DETAILED DESCRIPTION OF THE INVENTION  
       [0057]    Referring now to the drawings where in like numerals correspond to similar elements throughout the several views and, more specifically, referring to FIGS. 1 a  and  1   b,  the present invention will be described in the context of exemplary motor control system  10  including a rectifier assembly generally illustrated in FIG. 1 a  which feeds an inverter assembly generally illustrated in FIG. 1 b  where each of the rectifier and inverter are controlled by a controller  22 . As known in the controls industry, rectifier (FIG. 1 a ) receives three-phase AC voltage on input lines  12 ,  14  and  16  and converts that three-phase voltage to a DC potential across positive and negative DC buses  18  and  20 , respectively. The DC buses  18  and  20  generally feed the inverter configuration (see again FIG. 1 b ) which converts the DC potential to three-phase AC voltage waveforms that are provided to a three-phase load via first, second and third inverter output lines  24 ,  26  and  28 , respectively.  
         [0058]    The rectifier assembly includes twelve separate switching devices identified by numerals  30 - 41 . The switching devices  30 - 41  are arranged between the positive and negative DC buses  18  and  20 , respectively, to provide six separate rectifier legs. Each rectifier leg includes two series connected switching devices that traverses the distance between the positive and negative DC buses  18  and  20 , respectively. For example, a first rectifier leg includes switches  30  and  36  that are in series between positive bus  18  and negative bus  20 , a second rectifier leg includes switches  31  and  37  that are series connected between buses  18  and  20 , a third rectifier leg includes switches  32  and  38  that are series connected between buses  18  and  20 , and so on. The nodes between switches in each rectifier leg are referred to as common nodes. One common node between switches  32  and  38  is identified by numeral  46 .  
         [0059]    Each of input lines  12 ,  14  and  16  is separately linked to two different common nodes. For example, as illustrated, line  14  is linked to common node  46  between switches  32  and  38  and is also linked to the common node (not numbered) between switches  33  and  39 . In a similar fashion, input line  12  is linked to the common node between switches  34  and  40  and also to the common node between switches  35  and  41  while line  16  is linked to the common node between switches  30  and  36  and to the common node between switches  31  and  37 . In FIG. 1 a  (and also FIG. 1 b  described below) switch emitters, collectors and gates are identified via E, C and G labels, respectively, with the collectors and emitters of switches  30  and  36  qualified by “1” and “2” sub-labels (e.g., E 1 , E 2 , C 1 , C 2 ), to distinguish those emitters and collectors for additional explanation below.  
         [0060]    A control bus  48  which represents a plurality of different control lines links controller  22  separately to each one of the rectifier switches  30 - 41  for independent control. Controller  22  controls when each of the switches  30 - 41  turns on and when each of the switches  30 - 41  turns off. Control schemes that may be used by controller  22  to convert the three-phase voltages on lines  12 ,  14  and  16  to a DC potential across DC buses  18  and  20  are well known in the conversion art and therefore will not be described herein detail. Rectifier legs that have their common nodes (e.g.,  46 ) linked to the same input line are controlled in an identical fashion by controller  22 . For example, referring still to FIG. 1  a, each of switches  32  and  33  would be turned on and turned off at the same time by controller  22  and each of switches  38  and  39  would be turned on and turned off at the same times by controller  22  as the corresponding rectifier legs have the same common node  46  linked to line  14 .  
         [0061]    In addition to the components described above, the rectifier configuration illustrated in FIG. 1 a  also includes capacitors between DC buses  18  and  20  which are collectively identified by numeral  50 . Although only two capacitors are illustrated, it should be appreciated that a larger number of capacitors would typically be employed in any type of rectifier configuration. Capacitors  50  reduce the ripple in the potential between lines  18  and  20  as well known in the art.  
         [0062]    Referring now to FIG. 1 b,  the inverter configuration illustrated, like the rectifier configuration of FIG. 1 a,  includes twelve separate switching devices identified by numerals  61 - 72 . The switching devices  61 - 72  are arranged to form six separate inverter legs. Each inverter leg includes a pair of the switching devices  61 - 72  that is series arranged between the positive DC bus  18  and the negative DC bus  20 . For example, a first inverter leg includes switches  61  and  67  series arranged between buses  18  and  20 , a second inverter leg includes switches  62  and  68  series arranged between buses  18  and  20 , a third leg includes switches  63  and  69  series arranged between buses  18  and  20 , and so on.  
         [0063]    Common nodes between inverter leg switch pairs are referred to hereinafter as common nodes. In FIG. 1 b, an exemplary common node between switches  61  and  67  is identified by numeral  80 . In the illustrated embodiment, each output line  24 ,  26  and  28  is linked to two separate inverter leg common nodes (e.g.,  80 ). For example, output line  28  is linked to common node  80  between switches  61  and  67  and is also linked to the common node (not illustrated) between switches  62  and  68 . Similarly, output line  26  is linked to the common node between switches  63  and  69  and also to the common node between switches  64  and  70  while output line  24  is linked to the common node between switches  65  and  71  and is also linked to the common node between switches  66  and  72 .  
         [0064]    The control bus  48  linked to controller  22  is also linked separate to each of the inverter switches  61 - 72  to independently control the turn on and turn off times of those switches. As in the case of the rectifier switches of FIG. 1 a,  controller  22  controls the switches of the inverter legs that have common nodes linked to the same output line in an identical fashion. To this end, referring still to FIG. 1 b,  because the common nodes (e.g.,  80 ) corresponding to the first inverter leg including switches  61  and  67  and the second inverter leg including switches  62  and  68  are both connected to output line  28 , the first and second inverter legs are controlled in a similar fashion so that each of switches  61  and  62  is turned on and turned off at the same times and each of switches  67  and  68  are turned on and off at the same times.  
         [0065]    Referring to FIGS. 1 a  and  1   b,  the rectifier-inverter configuration includes commonly controlled switches so that the configuration can handle relatively high currents that may otherwise destroy the types of devices employed to configure the converters. In this manner relatively less expensive switches can be used to construct the converter assembly. The switches  30 - 41  used to configure the rectifier are typically identical and the switches  61 - 72  used to configure the inverter are typically identical. Depending on the configuration design, switches  30 - 41  may or may not be identical to switches  61 - 72 .  
         [0066]    Referring still to FIGS. 1 a  and  1   b,  switch manufacturers often provide power switching devices in prepackaged modules suitable to construct inverters and rectifiers. To this end, often, a complete 6-switch bridge will be provided as a separate and unique switching power package. Hereinafter it will be assumed that the  24  switches that comprise the rectifier and inverter in FIGS. 1 a  and  1   b  are provided in four separate 6-switch bridge packets where the first switching package includes switches  30 ,  31 ,  32 ,  36 ,  37  and  38 , the second switch package includes switches  33 ,  34 ,  35 ,  39 ,  40  and  41 , the third switch package includes switches  61 ,  62 ,  63 ,  67 ,  68  and  69  and the fourth switch package includes switches  64 ,  65 ,  66 ,  70 ,  71  and  72 . Unless indicated otherwise, hereinafter, the first, second, third and fourth switch packages will be identified by numerals  90 ,  92 ,  94  and  96 , respectively. Exemplary switch packets  90 ,  92 ,  94  and  96  are illustrated in FIG. 2 and are described in greater detail below.  
         [0067]    Referring now to FIG. 2, an exploded perspective view of an exemplary rectifier/ inverter converter assembly  100  is illustrated. Configuration  100  includes a heat sink member  102 , the four-switching modules  90 ,  92 ,  94  and  96  briefly described above, a bracket member  104 , a plurality of capacitors collectively identified by numeral  50 , a laminated bus bar  106  and a plurality of input and output bus bars identified by numerals  12 ′,  14 ′,  16 ′,  28 ′,  26 ′, and  24 ′.  
         [0068]    Each of switch packages  90 ,  92 ,  94  and  96  is similarly constructed and therefore, in the interest of simplifying this explanation, unless indicated otherwise, only switch package  90  will be described here in detail. Referring also to FIGS. 3 and 5, package  90  has a generally rectilinear shape having a length dimension L3, a width dimension W1 and a thickness dimension (not separately labeled). Although not illustrated in any of the drawings, device package  90  is characterized by a device thickness dimension that will be referred to herein by label T1 that is formed between the mounting or dissipating surface  122  (see FIG. 3) of the device and a connection plane defined by the top surfaces of the emitter and capacitor connection terminals that extend from the package housing. Package  90  has a first device or first linking edge  130  and a second device or second linking edge  132  that face in opposite directions and are separated by device width W1 as illustrated.  
         [0069]    Referring still to FIG. 1 a  and also to FIG. 2, package  90  includes switching devices  30 ,  31 ,  32 ,  36 ,  37  and  38  that are arranged in a single row relationship where the emitters and collectors for each one of the switching devices extend from opposite side of package  90  and are generally separated by the device width W1. For example, the emitter E 1  and collector C 1  extend from opposite sides of package  90  while emitter E 2  and collector C 2  for switch  36  extend in opposite directions. Adjacent switches within package  90  have their emitters and collectors extending in different directions. For example, referring to FIG. 1 a  and FIG. 2, switch  36  in FIG. 1 a  has its emitter E 2  and its collector C 2  extending in directions opposite those of emitter E 1  and collector C 1  of the first switch  30  adjacent thereto in the package  90 . Referring still to FIG. 3, package  90  is designed so that all of the emitter and collector terminals extend from the package housing within a single connection plane.  
         [0070]    Hereinafter, unless indicated otherwise, switching device connection terminals that are linked to any of bus bars  12 ′,  14 ′,  16 ′,  24 ′,  26 ′ or  28 ′ will be referred to as inter-converter terminals because those terminals are connected through their respective bus bars to components outside the converter configuration. Similarly, any device package terminals that are linked to laminated bus bar  106  will be referred to hereinafter generally as intra-converter terminals as those terminals are linked to other components within the converter assembly.  
         [0071]    As illustrated and described hereinafter, all of the inter-converter terminals extend from one side of package  90  while all of the intra-converter terminals extend from the opposite side of package  90  after the configuration in FIGS. 2 and 4 is assembled. In addition, after assembly, all of the intra-converter terminals for all of packages  90 ,  92 ,  94  and  96  extend in the same direction and form a connection line while all of the inter-converter terminals for packages  90 ,  902 ,  904  and  96  extend in the opposite direction and form a second connection line (see alignment generally in FIG. 2). The first and second connection lines form linking edges of the devices in the packages.  
         [0072]    Control ports are provided on a top surface of package  90  to facilitate linking of control bus  48  to the devices provided within package  90 . An exemplary control port in FIG. 2 is identified by numeral  120 .  
         [0073]    Package  90  has an undersurface  122  that is in thermal contact with the components inside the package housing that generate heat. Package  90  is designed so that surface  122  is substantially flat and can make substantially full contact with a heat sink surface when mounted thereto. It should be appreciated that, typically, only a portion of surface  122  may generate a relatively large percentage of the total amount of heat generated by the package and that the primary heat generating surface will likely be the central portion of surface  122 . A heat generating segment  124  or dissipating surface of package  92  is illustrated and includes a space that is framed by an outer space  126  that surrounds the heat generating space  124 . Space  124  generally corresponds to a space that is in direct contact with the package  90  components that conduct current and hence generate heat. Space  124  has a dissipating surface width dimension W2 associated therewith.  
         [0074]    As best in seen in FIGS. 2 and 3, each package  90  includes a plurality of small apertures, two of which are identified by number  128 , provided through the outer space  126  that frames the heat generating segment  124  (e.g., see device  92 ) as illustrated. Apertures  128  are provided to facilitate mounting packages  90 ,  92 ,  94  and  96  to sink member  102 .  
         [0075]    Referring still to FIG. 2, bus bars  12 ′,  14 ′,  16 ′,  28 ′,  26 ′ and  24 ′ are to be linked to input lines  12 ,  14 ,  16  and output lines  28 ,  26  and  24  in FIGS. 1 a  and  1   b,  respectively. The linking relationship between bus bars and associated lines is highlighted by the bus bars being labeled with numbers that are identical to the line numbers to which they connect followed by a “′” indicator.  
         [0076]    Each of input and output bus bars  12 ′,  14 ′,  16 ′,  24 ′,  26 ′ and  28 ′ are simply steel bars that either have an “L” shape or a “T” shape. Each bar  12 ′,  14 ′,  16 ′,  24 ′,  26 ′ and  28 ′ is designed to link input or output lines to a subset of four of the inter-converter terminals. For example, referring to FIGS. 1 a  and  2 , L-shaped bus bar  16 ′ is constructed and dimensioned so as to link together each of the emitter E 1  for switch  30 , the collector C 2  for switch  36 , the emitter for switch  31  and the collector for switch  37  and, to this end, includes four separate apertures for receiving some type of mechanical securing component (e.g., a bolt), a separate aperture corresponding to each one the emitters and collectors to be connect by bar  16 ′. Each of the other bus bars  12 ′,  14 ′,  24 ′,  26 ′ and  28 ′ has a construction similar to bus bar  16 ′ and therefore, in the interest of simplifying this explanation, the other bars will not be described here in detail. It should suffice to say that the bus bars link emitters and collectors among the switch packages  90 ,  92 ,  94  and  96  in a manner that is consistent with the schematics illustrated in FIGS. 1 a  and  1   b.    
         [0077]    Referring once again to FIG. 3 and also to FIG. 4, heat sink member  102  is an elongated and, in the illustrated embodiment, substantially rectilinear metallic (e.g., aluminum, copper, etc.) member that extends from a first end  144  to a second end  146 , has first and second lateral surfaces  148  and  150 , respectively, that face in opposite directions and extend along the entire length between ends  144  and  146  and also includes a first or first mounting surface  140  and a second oppositely facing mounting surface  142 . As best illustrated in FIG. 2 (and also illustrated in FIG. 6), mounting surface  140  has a width dimension W3 that separates the lateral surfaces  148  and  150 , respectively and has a length dimension L5. Mounting surface  140  and lateral surfaces  148  and  150  form first and second lateral edges  149  and  151 , respectively. In at least one embodiment of the present invention, sink width W3 is substantially similar to the device package width W1 so that, as illustrated in FIG. 2, device packages  90 ,  92 ,  94  and  96  are mounted in a side-by-side single row fashion to be accommodated on mounting surface  140 .  
         [0078]    As best seen in FIG. 3, in at least one embodiment, sink member  102  includes two separate components that are secured together. The two components including a body member  160  and a cover member  162 . Referring also to FIG. 5, body member  160  has thickness dimension T2 which is generally greater than the thickness dimension (not separately identified) of member  162 . Together, body member  160  and cover member  162  have a thickness dimension T3.  
         [0079]    As illustrated in FIGS. 3 and 6, body member  160  includes a second surface  164  opposite mounting surface  140  and forms a cavity  166  therein which extends substantially along the length of body member  160  from the first end  144  of the sink member to the second end  146 . Cavity  166  has a cavity or channel depth Dc and forms a cavity or channel surface  69 . In the illustrated embodiment, cavity  166  stops short of each of the ends  140  and  146 , has a cavity length dimension L4 and has a cavity width or receiving dimension W4. Channel walls are provided on opposite sides of cavity  166  that have a thickness that is similar to the width dimension of the framing (i.e., the mounting flange) portion  126  of device surface  122  (see FIG. 3). The cavity width dimension W4, in at least some embodiments, is similar to the width dimension W2 of the primary heat generating portion or segment  124  of the package dissipating surface  122 .  
         [0080]    Cavity length dimension L4, in some embodiments, is substantially similar to a dimension formed by the oppositely facing edges of the dissipating surfaces of the device packages at the ends of the device row attached to the sink member. This dimension will be slightly smaller than the combined lengths (e.g., L3) of the device packages  90 ,  92 ,  94  and  96  in most cases. When cavity  160  is so dimensioned, a relatively small sink assembly is constructed which still provides effective cooling to devices attached thereto.  
         [0081]    Referring still to FIGS. 3 and 6, within cavity  166 , body member  160  includes three separate cavity dividing members including a central or first dividing member  180  and second and third lateral dividing members collectively identified by numeral  182 . As its label implies, central dividing member  180  is positioned centrally within cavity  166  and generally divides the cavity into two separate channels. Central dividing member  180 , in the illustrated embodiment, extends such that its distal end is flush with surface  164  of body member  160 . In addition, central dividing member  180  extends all the way to a first end  184  of cavity  166  but stops short of a second end  186  of the cavity, the second end  186  being opposite first end  184 .  
         [0082]    Each of the second and third dividing members  182  is positioned on a different side of central member  180  and each stops short of both the first cavity end  184  and the second cavity end  186 . In addition, each of dividing members  182  forms a plurality of openings so that liquid flowing on either side of the member can pass to the opposite side of the member. Exemplary openings are identified by numeral  190  in FIG. 3. Like central member  180 , in the illustrated embodiment, each of the second and third lateral members  182  extends such that its distal end is flush with surface  164  of body member  160 .  
         [0083]    With openings  190  formed in each of dividing members  182 , what remains of members  182  includes protuberances  290  that essentially break up the flow of coolant through the two channels formed within the cavity  166  as described in greater detail below. In the illustrated embodiment the protuberances  290  are essentially equi-spaced along the channel lengths.  
         [0084]    At the first end  144  of the sink member, in the illustrated embodiment, body member  160  forms an inlet or receiving chamber  192  and first and second nozzle passageways  194  and  196 , respectively. Inlet chamber  192  is formed between end  144  and cavity  166  and is connected to cavity  166  on one side of central member  180  by first nozzle passageway  194  and is connected to cavity  166  on the other side of central dividing member  180  by second nozzle passageway  196 . Inlet chamber  192  has a relatively large cross-sectional area when compared to either of nozzle passageways  194  and  196  so that inlet chamber  192  can act as a reservoir for providing liquid under pressure to cavity  166  through the nozzle passageways  194  and  196 . In the illustrated embodiment, each of the second and third lateral dividing members  182  is positioned such that the protuberance  290  closest to the inlet nozzle passageway  194  or  196  is aligned therewith. At second end  146  of body member  160 , body member  160  forms a channel extension  210  having a width dimension that is less than the cavity width W4.  
         [0085]    Body member  160  can be formed in any manner known in the art. One method for providing member  160  includes providing the member without cavity  166  and scraping metal out of surface  164  to provide a suitable cavity. Another method may be to form body member  160  in a mold. Other manufacturing processes are contemplated.  
         [0086]    Cover member  162  is a substantially planar and rigid rectilinear member having a shape which mirrors the shape of surface  164 . Member  162  forms an inlet opening  200  at a first end  204  and an outlet opening  202  at a second  206 . The inlet  200  and outlet  202  are formed such that, when cover member  162  is secured to surface  164 , inlet  200  opens into inlet channel  192  and outlet  202  opens into extension  210 .  
         [0087]    To secure cover member  162  in a hermetically sealed manner to surface  164 , any method known in the industry can be employed. One method which has been shown to be particularly useful in providing a hermetic seal between cover member  162  and body member  160  has been to use a vacuum brazing technique where a bead of brazing material is provided along surface  164  of body member  160 , cover member  162  is provided on surface  164  with the brazing bead sandwiched between members  162  and  160  and then the component assembly is subjected to extremely high heat thereby causing a brazing function to occur. Other securing methods are contemplated.  
         [0088]    As illustrated, each of body member  160  and cover member  162  form a plurality of apertures (not separately numbered) for receiving mechanical components such as screws, bolts, etc., for mounting device packages  90 ,  92 ,  94  and  96  and, perhaps, other electronic devices, to the sink member  102 . In addition, body member  160  and/or cover member  162  may include other apertures for mounting other converter components (e.g., the bracket described below) to sink member  102  and/or to mount the sink member  102  within a converter housing for support.  
         [0089]    Referring once again to FIG. 2 and also to FIG. 5, capacitors  50  are standard types of capacitors and, to that end, generally include a cylindrical body member having a first end  220  and a second end  222  opposite the first end  220  where terminals  224  and  226  extend from each first end  220  and a heat conducting extension  228  (see FIG. 5) extends centrally from each second end  222 . The heat conducting extensions  228 , as the label implies, conducts most of the heat from the central core of the capacitor. Each capacitor  50  has a length dimension L1 which separates the first and second ends  220  and  222 .  
         [0090]    Referring now to FIGS. 2, 4 and  5 , bracket member  104  is, in at least one embodiment, formed of a heat conducting, rigid material such as aluminum or copper. Bracket member  104  includes a proximal member  230 , an intermediate member  232  and a distal member  234 . Proximal member  230  includes a flat elongated member which has a length substantially equal to the length of sink member  102 . Proximal member  230  forms a plurality of mounting apertures along its length which align with similar apertures (not illustrated) in the surface  142  formed by cover member  162  (see again FIG. 3).  
         [0091]    Intermediate member  232  forms a 90° angle with proximal member  230  and extends from one of the long edges of member  230 . Similarly, distal member  234  extends from the long edge of intermediate member  232  opposite the edge linked to proximal member  230  and forms a 90° angle with intermediate member  232 . The 90° angle formed between intermediate member  232  and distal member  234  is in the direction opposite the angle formed between proximal member  230  and intermediate member  232  so that distal member  234  extends, generally, in a direction opposite the direction in which proximal member  230  extends. Although not illustrated, distal member  234  forms a plurality of apertures through which the heat dissipating capacitor extension members  228  extend for mounting the capacitors  50  thereto. In the illustrated embodiment, distal member  234  forms two rows of substantially equi-spaced apertures for receiving the capacitors  50  and arranging the capacitors  50  in two separate rows.  
         [0092]    Referring again to FIGS. 2, 4 and  5 , laminated bus bar  106  includes a substantially planar member having a general shape similar to the shape of distal member  134 . Although not illustrated, it should be appreciated by one of ordinary skill in the art that laminated bus bar  106  includes several metallic conducting layers where adjacent layers are separated by insulating layers and wherein different ones of a conducting layers are linked to connecting terminals along one edge of the bus bar. Exemplary connecting terminals are identified by numeral  240  in FIGS. 2 and 4.  
         [0093]    In addition, although not illustrated, separate vias are provided in an underside of bus bar  106  which facilitate connection of particular points and particular conducting laminations within bar  106  to the capacitors juxtaposed hereunder when the converter assembly is configured. More specifically, referring to FIGS. 1 a  and  1   b  once again, bus bar  106  links various emitters and collectors of the switching devices  30 - 41  and  61 - 72  to the positive and negative DC buses separated by the capacitors  50  as illustrated. Thus, for example, bus bar  106  links the collector of switch  30  to the positive DC bus  18 , the emitter of switch  36  to the negative DC bus, the collector of switch  31  to the positive DC bus  18 , the emitter of switch  37  to the negative DC bus  20 , and so on.  
         [0094]    It should be appreciated that bus bar  106  can have an extremely simple and hence minimally expensive construction when used with a sink and switching device configuration that aligns all intra-converter connection terminals in a single line and in a single connection plane. Here only a minimal number of laminate layers are required and no vias are required to link to the switching devices as connection terminals  240  are within the same plane as the device terminals.  
         [0095]    With the converter components configured as described above, a particularly advantageous converter assembly can be assembled as follows. First, after the cover member  62  has been hermetically sealed to body member  160 , device packages  90 ,  92 ,  94  and  96  are mounted to mounting surface  140  of sink member  102  so as to form a single device row as illustrated best in FIG. 4. Next, bracket member  104  is secured to surface  142  of cover member  102  so that intermediate member  232  generally extends away from sink member  102  and so that distal member  234  also extends generally away from sink member  102 . Capacitors  50  are next mounted to distal member  234  with their extending heat dissipating extensions  228  passing through apertures in member  234  and so that the capacitors  50  form two capacitive rows as illustrated in FIGS. 2 and 5.  
         [0096]    At this point, it should be appreciated that, when bracket member  104  is suitably dimensioned, the connection terminals  224  and  226  that extend from the first ends  220  of the capacitors  50  should be within the same connection plane as the intra-converter connection terminals extending toward the capacitors  50  from each of device packages  90 ,  92 ,  94  and  96 . To this end, the bracket member  232  should be chosen such that the length dimension L2 of intermediate member  232 , when added to the sink member thickness T3 and the device thickness T1 (not illustrated), essentially equals the capacitor length L1. When any of the sink member  102 , the capacitors  50  or the device packages (e.g.,  90 ) are replaced by other components having different dimensions, the differently dimensioned components can be accommodated and the capacitor and device package connecting terminals can be kept within the same plane by selecting a bracket member  104  having a different intermediate member  232  length dimension L2. Thus, the bracket-sink member assembly renders the sink member extremely versatile when compared to previous sink configurations that required multi-plane serpentine coolant paths.  
         [0097]    With the capacitor connecting terminals and the intra-converter terminals extending from the device packages within the same connection plane, planar and relatively simple bus bar  106  is attached to the capacitor and intra-converter terminals thereby linking the various terminals to the positive and negative buses  18  and  20  in the fashion illustrated in FIGS. 1 a  and  1   b  above.  
         [0098]    Continuing, the input and output bus bars  12 ′,  14 ′,  16 ′,  24 ′,  26 ′ and  28 ′ are next linked to the inter-converter connection terminals as illustrated in FIG. 4 and to link the emitters and capacitors of the switching devices  30 - 41  and  61 - 72  at the common nodes (e.g.,  46 ,  80 , etc.) as illustrated in FIGS. 1 a  and  1   b.    
         [0099]    Referring now to FIG. 5, when all of the components described above are secured together in the manner taught, an extremely compact converter assembly that requires a relatively small volume is configured. In fact, as illustrated, a space  280  is formed adjacent surface  142  of cover member  162  and adjacent intermediate member  232  where additional components such as the components required to configure controller  22  can be mounted. In some embodiments, at least some of the components of controller  22  will be mounted within cooling space  280  to a second mounting surface formed by surface  142  of cover member  162  so that the mounted components dissipate heat into sink member  102 .  
         [0100]    Referring again to FIGS. 3 and 6, with cover member  162  secured to surface  164 , when liquid is pumped through inlet  200  and into inlet chamber  192 , after chamber  192  fills with liquid, the liquid is forced through each of restricted nozzle inlets  194  and  196  into opposite sides of cavity  166  (i.e., into different halves of cavity  166  where the halves are separated by central dividing member  180 ). Because the nozzle passageways  194  and  196  are restricted, the coolant is forced therethrough under pressure which should overcome any pressure differential that exists within the opposite sides of cavity  166 . As the liquid passes through cavity  166  on its way to and out outlet  202 , the liquid heats up between first channel end  184  and second channel end  186  and a phase change occurs wherein at least a portion of the liquid, as heat is absorbed, changes from the liquid state the state gas thereby forming bubbles within cavity  166 .  
         [0101]    Protuberances  290  cause excessive amounts of turbulence within cavity  166  as the protuberances  290  redirect liquid along random trajectories within the channels. The excessive turbulence within cavity  166  is such that essentially no gas pockets form on the internal surfaces of the cavity  166  or the portion of cover member  162  enclosing cavity  166 . In embodiments where sink member  102  is vertically aligned, bubbles that form within the cavity float upward under the force of liquid flow and the force of their own buoyancy. The bubbles proceed out the outlet  202  and are thereafter condensed by the cooling system attached thereto as the refrigerant is cooled.  
         [0102]    In FIG. 6, as indicated above, cavity  166  has a width dimension W4 that is, at least in one embodiment, similar to the width dimension W2 of the heat generating portion of device or package surface  122  (see also FIG. 3). Where dimension W2 is smaller, it is contemplated that the dual channel aspect of cavity  166  may not be required. For example, assume dimension W2 is half the dimension illustrated in the figures. In this case, the cavity  166  may be made approximately half the illustrated dimension and hence central member  180  may not be needed.  
         [0103]    Experiments have shown that if width dimension W4 is too large and no dividers  180  are provided along the cavity length L4, the turbulence generated by the protuberances  290  is substantially reduced. Thus, for instance, assume member  180  were removed from cavity  166 . In this case much of the coolant pumped into cavity  166  through passageways  194  and  196  would pass relatively calmly through to the outlet end  186  of cavity  166 . The maximum width of each channel formed within cavity  166  is going to be a function of various factors including cavity depth, coolant employed, coolant pressure, the quantum of heat generated by device packages mounted to the sink, etc.  
         [0104]    It should be appreciated that the protuberances  290  and divider  180  within cavity  166  are specifically provided to increase channel turbulence to a level that eliminates gas pockets on channel surfaces. Without gas pockets on the channel surfaces, refrigerant/coolant is in substantially full contact with all channel surfaces and the temperature differential between the first and second channel ends  184  and  186  is substantially reduced. The smaller channel temperature differential means that devices mounted to sink member  102  have more similar operating characteristics as desired.  
         [0105]    Referring now to FIG. 9 a method  300  according to one aspect of the present invention is illustrated. Here, at block  302 , a body member  160  (see again FIG. 3) having a limited width dimension W3 and a length L5 is provided where the limited width dimension is substantially similar to or identical to the width dimension W1 of the devices to be attached thereto. At block  304 , a cavity is formed in a first surface of the body member  160  that extends substantially along the entire length dimension L5. The cavity is illustrated as  166  in FIG. 3. At block  306 , a cover member  162  is provided that is consistent with the teachings above. At block  308  an inlet is formed in one of the body member and the cover member. At block  310  an outlet is formed in one of the body member and the cover member. As above, the inlet and outlet formed should open into opposite ends of the cavity or channel  166 . At block  312 , the cover member  162  is hermetically sealed in any manner known in the art to the body member  160  thereby providing an enclosed channel having only a single inlet and a single outlet at opposite ends. Continuing, at block  314 , power switching devices for packages  90 ,  92 ,  94  and  96  are mounted to the second or mounting surface with their dissipating width dimensions substantially parallel to the receiving width dimension W3 of the heat sink.  
         [0106]    It should be understood that the methods and apparatuses described above are only exemplary and do not limit the scope of the invention, and that various modifications could be made by those skilled in the art that would fall under the scope of the invention. For example, while the sink member  102  is described as being formed of two components other configurations are contemplated. In addition, the protuberances  290  may take other forms that cause a suitable amount of turbulence within the channel. For instance, in FIG. 7 another embodiment of the body member is illustrated. In FIG. 7 components similar to the components of FIG. 6 are identified by identical numbers followed by an “a” qualifier. In FIG. 7, instead of providing substantially rectilinear protuberances as in FIG. 6, triangular protuberances  290 a are provided on either side of member  280 . Moreover, the protuberances may be formed by any channel surface although forming the protuberances on the surface opposite the heat generating devices (i.e., opposite the mounting surface) increases the total surface area proximate the heat generating device that is in contact with the coolant. Furthermore, both the cover and the body member may form protuberances and, in some embodiments, the cover member may form part or all of the cavity  166 .  
         [0107]    In addition, while the protuberances  290  are illustrated as being equi-spaced, equi-spacing is not required and, in fact, it may be advantageous to provide protuberances that cause a greater amount of turbulence at the outlet end of the channel than at the inlet end as the coolant at the outlet end could be slightly warmer and hence could generate more problematic vapor bubbles.  
         [0108]    Moreover, more than one divider may be provided in a cavity. In this regard, referring to FIG. 8, another inventive embodiment  160   b  of the body member is illustrated. In FIG. 8 components similar to components described above are identified by the same number followed by a “b” qualifier. In FIG. 8 cavity  166   b  is twice as wide as the cavity  166  in FIG. 6. Here, to ensure sufficient turbulence to eliminate stagnant gas pockets from the cavity surface, three separate divider members  271 ,  273  and  275  are provided that equally divide cavity  166   b  along its width. In addition, separate inlet passageways  251 ,  253 ,  255  and  257  are provided that open from inlet chamber  192   c  into each separate channel within cavity  166   b  and separate lines of protuberances  261 ,  263 ,  265  and  267  are formed within the separate channels. Thus, the protuberance concept has application in wider sink assemblies also although it is particularly advantageous in long sink assemblies for the reasons described above.  
         [0109]    To apprise the public of the scope of this invention, the following claims are made: