Abstract:
A dual pole busbar power connector including opposing elements configured to form a slot configured to receive a dual-pole blade therebetween. The slot extends from busbars to opposing element distal ends. The opposing elements each includes: a first contact extending into the slot from the opposing element; and a second contact extending into the slot from the opposing element and disposed farther from a slot busbar end than the first contact. When the dual-pole blade is inserted in the slot the first contact contacts a respective blade element at a location in the slot more proximate the slot busbar end than a slot distal end.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention is related to power connectors. In particular, the present invention is related to a dual pole power connector for enabling a power connection to dual pole parallel power busbars. 
       BACKGROUND OF THE INVENTION 
       [0002]    Transmission of power through an electric circuit results in energy losses. In circuits where the voltage does not remain constant, such losses may be the result of many factors, including conductive losses as well as losses associated with a voltage that changes, such as inductive losses and capacitive losses. Conductive losses include heat loss resulting from resistance of the conductors and electrical connectors between conductors. Inductive losses may be proportional to a frequency of voltage change and a circuit&#39;s inductance, and/or a speed of a voltage change and the circuit&#39;s inductance. A circuit&#39;s inductance may be influenced by the geometry of the circuit itself, or the geometry of the electrical connector itself. 
         [0003]    The nature of power transmitted through electric circuits is continuously changing. For example, in switched circuits, the speed at which a voltage may change is constantly increasing with the onset of new more advanced high switching speed semiconductors. This is a consequence of the new semiconductor technology and the need to obtain high power density in electronic circuits. Consequently, because inductive losses are proportional to a speed of a voltage change, and are related to the geometry of the circuit, increased attention must be paid to the geometry of electrical connectors in order to minimize inductive losses. Thus, there remains room in the art for improvement. 
       BRIEF DESCRIPTION OF THE INVENTION 
       [0004]    An embodiment is directed toward a dual pole busbar power connector including opposing elements configured to form a slot configured to receive a dual-pole blade therebetween. The slot extends from busbars to opposing element distal ends. The opposing elements each includes: a first contact extending into the slot from the opposing element; and a second contact extending into the slot from the opposing element and disposed farther from a slot busbar end than the first contact. When the dual-pole blade is fully inserted in the slot the first contact mates a respective blade element at a location in the slot more proximate the slot busbar end than a slot distal end. 
         [0005]    Another embodiment is directed toward a dual pole electrical connector including: at least one electrically conductive element for each busbar of a dual parallel busbar power conversion equipment, the electrically conductive element including a first contact, wherein when a dual-pole blade is inserted into the dual pole electrical connector the first contact electrically connects a respective busbar to a respective blade element via a first element first contact path. The first element first contact paths of respective poles form a loop comprising an region therebetween comprising a cross section, and a dual pole electrical connector inductance is influenced by a size of the cross section, and the cross section is configured by the first contact paths to keep the dual pole electrical connector inductance below seven nanohenries. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The invention is explained in the following description in view of the drawings that show: 
           [0007]      FIG. 1  shows a cross section of a side view of an electrical connector. 
           [0008]      FIG. 2  shows a perspective view of a blade commonly used with the electrical connector of  FIG. 1 . 
           [0009]      FIG. 3  shows a cross section of a side view of the electrical connector of  FIG. 1  with the blade of  FIG. 2  inserted. 
           [0010]      FIG. 4  is a close up of a portion of  FIG. 3 . 
           [0011]      FIG. 5  schematically shows a current path through the connector of  FIG. 1 . 
           [0012]      FIG. 6  schematically shows the current loop of  FIG. 5  and a cross section of the region bounded by the current path. 
           [0013]      FIG. 7  schematically shows an alternate current loop and a cross section of the region bounded by the current loop. 
           [0014]      FIG. 8  shows a cross section of a side view and current path of another embodiment of an electrical connector. 
           [0015]      FIG. 9  schematically shows the current path of  FIG. 8  and a cross section of the region bounded by the current path. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0016]    New semiconductor technologies are capable of providing much faster switching than has been seen in the art. Specifically, when a voltage is changed from a first voltage to a second voltage the change ideally would be instantaneous. Were this signal profile depicted on a graph with voltage on the y-axis and time on the x-axis, the line representing the voltage would, ideally, be vertical when the voltage changed. This line, i.e. the signal edge, however, is not vertical, and historically this has been the result of the switching technology. However, with the advent of switching technology using silicon carbide, for example, the switching equipment is capable of much faster transitions, i.e. the signal edge slope is significantly steeper. However when the new switching technology was used with conventional circuit hardware, including the electrical connectors, the expected increased efficiency of the relatively “faster edge” was not realized to its potential. Upon initial investigation it was discovered that efficiency gains realized by the faster edge were being offset by increased losses in the conventional circuit hardware associated with that same faster edge. Upon further investigation, it was discovered that certain prevalent conventional connectors, such as Tyco/Elcon “Crown Clip” connectors, as well as Anderson Power Products “Power Clip” connectors, possess certain geometries. Without being bound by any particular theory, it is believed that this geometry, which may best be considered a “loop” in terms of its contribution to the total inductance of the electrical connector, causes electrical losses in the circuit because it resists the change of faster edge switching. The inductance of the geometry has been present even with relatively slow edge switching, but the losses were negligible because the transition was slower. However, as the edge speed increases the losses are no longer negligible. The identified geometry is like a loop in the traditional sense of the term, where one may envision a coiled wire, and thus identification of the inductance inducing geometry was a significant step in itself. 
         [0017]    In addition, with the advent of the “faster edges,” switching frequencies themselves can in turn be increased. For example, frequencies of 10 kHz have been possible with relatively slower edge technologies. However, switching equipment had been the limiting factor because that technology had a relatively long transition time (edge) between the first and second voltages. However, with the advent of the new switching technologies, the switching equipment was not the limiting factor anymore, but as described above, the hardware had become the limiting factor. However, the demand for higher switching speed remains, and thus the recognition of the conventional geometry and innovative new design will permit switching speeds to increase in excess of 500 kHz, making the resulting geometry, although seemingly simple, critical for technological advancement. 
         [0018]    Inductance resulting from loops in an electrical circuit, i.e. a signal path, can be modeled with various known equations, but in general terms if one wants to reduce or eliminate a loop one can reduce a cross sectional of a region bound by the conductor(s) that form the loop (i.e. the cross section). As a result, the inventors have devised a power connector that significantly changes the current flow path geometry present in connectors of earlier designs, minimizing the region, and hence the cross section of the region, bounded by the conductors forming the loop. They have done this by adding an electrical contact at a point close to the busbar. The relevance of the contact, it is believed, is that its location is specifically chosen to reduce the cross section of the region bound by the newly identified inductance causing loop. 
         [0019]    The connector described below is suited for making an electrical connection between parallel busbars, each busbar being part of a single circuit, and a blade that is inserted into a slot in the connector, shown later. Thus, as used herein, a dual pole connector is a connector used to establish electrical communication between at least two busbars of a single circuit, and a component to be run off that circuit, where circuit comprises a first busbar, the component, and a second busbar. Turning to the drawings,  FIG. 1  shows a side view of a dual pole busbar power connector (“connector”)  10 . The connector has a housing  12  to hold two opposing elements, first element  14  and second element  16 . In an embodiment these are electrically connected to first busbar  18 , which serves as one pole of a circuit, and second busbar  20 , which serves as a second pole of a circuit, respectively, via first element flanged end  22  and second element flanged end  24 . However, this electrical connection may be made in any manner known to those of ordinary skill in the art. First element  14  may include first element first contact  26 , and second element  16  may include second element first contact  28 . In an embodiment, first element first contact  26  may be in electrical communication with first busbar  18  via a first element first contact plate  30 , and second pole first contacts may be in electrical communication with a second busbar  20  via a second element first contact plate  32 . However, again, electrical communication between the first contacts and the busbars may be made in any manner known to those of ordinary skill in the art. In an embodiment, first element first contact  26  and second element first contact  28  may be resilient and may oppose each other. First element  14  may include first element second contact  34 , and second element  16  may include second element second contact  36 . These second contacts may be resilient and may oppose each other. Any contacts in the embodiments may also include a plurality of contacts, or a line or plane of contact, and may extend across a width of the any surface they are intended to contact. It can be seen that a slot  38  is formed between the first element  14  and second element  16 . In an embodiment it can also be seen that a distance  40  between first element  14  and second element  16  at the first contacts  26 ,  28  is greater than a distance  42  between first element  14  and second element  16  at the second contacts  34 ,  36 . Slot  38  has slot length  44 , which is a distance from first busbar surface  46  and second busbar surface  48  to distal ends  50  of the first element  14  and second element  16 . 
         [0020]    A dual pole blade  52  as shown in  FIG. 2  is inserted into slot  38 . Dual pole blade  52  may include a first blade element  54  and a second blade element  56  separated by an insulator  58 . First blade element  54  includes first blade element tip  60  and second blade element  56  includes second blade element tip  62 , which is the portion of the dual pole blade that is first inserted into slot  38  and when fully inserted rests closest to the first busbar  18  and second busbar  20 . 
         [0021]      FIG. 3  shows the dual pole blade  52  inserted into the connector  10 . It can be seen in an embodiment that first element first contact  26  contacts the first blade element  54  at first blade element tip  60 , and second element first contact  28  contacts second blade element  56  at second blade element tip  62 . First element second contact  34  contact first blade element  54  at a location farther from the busbars, and likewise second element second contacts  36  contact the second blade element  56  at a location farther from the busbars. As can be seen in  FIG. 4 , which is an amplified view of first element first contact  26  and second element first contact  28 , cross section  64  of the region bounded in part by a first element first contact path  66  and a second element first contact path  68 . Also seen is the first element first contact path  66 , which is the path from the first element first contact  28  where it contacts the first busbar  18 , through the first element first contact  26 , to where the first element first contact  26  makes contact with the first blade element  54 . Similarly, the second element first contact path  68  is the path from the second element first contact  28  where it contacts the second busbar  20 , through the second element first contact  28 , to where the second element first contact  28  makes contact with the second blade element  56 . 
         [0022]    Thus, as can be seen in  FIG. 5 , the identified geometry, loop  70 , follows the current path from the first busbar  18 , through the first element first contact  26 , up the first blade element  54 , returning down the second blade element  56 , through the second element first contact  28 , to the second busbar  20 . 
         [0023]      FIG. 6  a schematic of the shape of first contact loop  70  of  FIG. 4 , showing cross section  64 , and second cross section  72 . Second cross section  72  is shown to illustrate the concept, because there is a region, albeit very small, between the first blade element  54  and the second blade element  56 . However, second cross section  72  is small relative to cross section  64 , and its contribution to the inductance of the connector is relatively negligible. Further, it is relatively difficult to eliminate this region due to the electrical need to keep the first blade element  54  and the second blade element  56  electrically isolated. As a result, the cross section  64  receiving attention can be described as a cross section of the region bound by the first element first contact path  66  and the second element first contact path  68 . 
         [0024]    In the embodiment shown in  FIG. 6 , cross section  64  has already been configured to be as small as possible because the first element first contact path  66  and the second element first contact path  68  are as short as possible, and are also close together. Either of these factors can be used to sufficiently reduce the cross section, and in this embodiment both are used for maximum benefit. It is this configuration, which has the most minimized cross section  64 , which permits the relatively fast edge signals to propagate through the connector with the least limiting inductance. 
         [0025]    By way of comparison to  FIG. 6 , shown in  FIG. 7  is second contact loop  74  that current would travel along if first element first contact  26  and second element first contact  28  were not present. In that case electrical communication with the first blade element  54  and a second blade element  56  would be through the first element second contact  34  the second element second contacts  36  respectively, which results in second contact loop  74 . As shown in  FIG. 7  when compared to  FIG. 6 , the cross section  76  bounded by this second contact loop  74 , i.e. this geometry, is much larger, and consequently would have a much larger inductance relative to the geometry of  FIG. 5 . 
         [0026]    The inventors have found that connectors with contact paths similar to that of  FIG. 7  have inductance of seven nanohenries and above. They have also found that connectors with geometries similar to that of  FIG. 5  have inductance of below seven nanohenries. In certain embodiments, such as those shown in  FIG. 5 , these connectors have inductances of 1 to 1.5 nanohenries. Any reduction in the cross section of the region bounded by the current path over that of other configurations will correspond to a reduction in the inductance, and therefore any reduction in cross section is an improvement. Thus, it can be seen that the geometry disclosed in  FIG. 1  is a significant improvement over other geometries used in the art. 
         [0027]    In an alternate embodiment shown in  FIG. 8 , connector  10  has first element  78  and second element  80 . Each in turn has first element first contact  82  and second element first contact  84  respectively. The loop  86  that the current would follow through this embodiment would be similar to the other loops. As shown in  FIG. 9 , the cross section  88  bounded by the geometry is a little larger than that shown in the embodiment of  FIG. 5 , but still less than that shown in  FIG. 7 , and thus an advantage is still realized over other configurations. Various other configurations are envisioned to be within the scope of this disclosure, so long as those configurations reduce the cross section of the region bounded by the current path below that of the other configurations. It is further noted that some of the current may flow through the second contacts of the connectors, and thus not all the current will be subject to the improved geometry, but enough of the current will follow the improved current paths that the above described improvements will be realized. Other considerations may require the presence of the second contacts, such as stabilizing the blade, or increasing contact area in order to maximize current flow capacity, and thus they have not necessarily been eliminated from every embodiment. Conversely, they may not be present in an embodiment where their presence is not needed. 
         [0028]    While various embodiments of the present invention have been shown and described herein, it will be apparent that such embodiments are provided by way of example only. Numerous variations, changes and substitutions may be made without departing from the invention herein. Accordingly, it is intended that the invention be limited only by the spirit and scope of the appended claims.