High current busbar system for low-profile power shelves

A low profile (1U) power distribution system includes a power shelf assembly having a first side and an opposing second side. First and second bus bars extend across the assembly and substantially in parallel with the first and second sides, the second bar positioned behind the first bar. One row of power supply pins extends from the bars to engage power supply units within the assembly. A first set of pins extends from the first bus, while a second set extends from the second bar and protruding through respective apertures in the first bar. An insulating material may be provided to electrically insulate power supply pins of the second bar from the first bar. The reduced height profile of the bars allows for cooling air to pass through the remaining >50% of the assembly, which may now desirably include additional electrical circuits within the cooling channel.

A portion of the invention of this patent document contains material that is subject to copyright protection. The copyright owner has no objection to the reproduction of the patent document or the patent invention, as it appears in the U.S. Patent and Trademark Office patent file or records, but otherwise reserves all copyright rights whatsoever.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims benefit of U.S. Provisional Patent Application No. 62/101,430, dated Jan. 9, 2015, and which is hereby incorporated by reference.

Not Applicable

Not Applicable

BACKGROUND OF THE INVENTION

The present invention relates generally to the field of power distribution systems. More particularly, the present invention relates to low-profile power shelves incorporating one or more switch mode power supplies providing a relatively low DC output voltage (e.g. 12V) at very high current (e.g. 1500 A) to power servers, storage or networking equipment.

With ever-increasing power consumption demands in server equipment, for example, increasing or at least more reliable airflow rates are needed to effectively cool such high power distribution systems. The associated electrical components are typically cooled by air moving in parallel airflow channels, through convection or otherwise forced-air mechanisms (e.g., fans or blowers).

However, particularly with respect to certain low-profile configurations (e.g., single “1U” rack units) the airflow channels are often restricted in size, thereby stressing the cooling abilities of the system. This may be even further exacerbated by the typical presence of electrical components, data cables and power cables which are disposed alongside the necessary bus bars. Still further, conventional cooling tools such as heat sinks with dedicated forced-air mechanisms typically require a height profile which is incompatible with for example a 1U power shelf.

BRIEF SUMMARY OF THE INVENTION

Briefly stated, an arrangement of bus bars is provided in a low profile power shelf where the buses are arranged one behind each other. The electrical connection of the rear bus bar is established by a substantially round pin protruding from the front bus bar and being isolated from the front bus bar. The bus bar arrangement uses less than 50% of the total shelf height.

An exemplary embodiment of a bus bar system involves the usage of two substantially rectangular copper or aluminum bus bars of the same size and arranged one behind the other in the shelf. The bus bars occupy only a first portion of the low profile shelf height (typically 50%), leaving the rest open so that the remaining shelf height can be used for other electrical connections and, significantly, allowing cooling air to pass from or to power supplies disposed within the power shelf assembly. This air will at the same time also cool the first and second (i.e., positive and negative connection) bus bars.

The electrical connection from the bus bars to the power supplies may be established by substantially round pins, wherein the single or multiple pin(s) connecting the rear bus bar to associated power supply outputs are protruding through corresponding apertures in the front bus bar. The pins can have an additional isolating material around them to avoid electrical short circuits. The front bus bar is connected through similar pins directly to associated power supply outputs.

This arrangement allows arrangement of the bus bars one behind the other instead of having them one on top of the other.

The proposed arrangement further preferably leaves enough space in the cross section of the shelf for additional low profile components and for air passing through the shelf to cool the power supply units and at the same time also the bus bars.

A power distribution system implementing such an arrangement may include, e.g., six power supplies each providing 3 kW of power at an output voltage of, e.g., 12V. This results in a total output current of 6×250 A=1500 A. The overall height of the low profile shelf is one rack unit (i.e., 1U or ˜40 mm). A copper bus bar conducting 1500 A of current without generating excessive losses should not be loaded with more than ˜3 A per mm2cross section. This results in a required bus bar cross section of at least 500 mm2. With the proposed arrangement, a bus bar of 20×25 mm can be selected, at least theoretically leaving >50% of the shelf cross section for other electrical connections and the air flow through the shelf.

The arrangements of bus bars one behind the other allows to reduce significantly the height occupied by such bar bars and allows for increased power outputs in low profile 1U shelves.

DETAILED DESCRIPTION OF THE INVENTION

Referring generally toFIGS. 1A-7, various exemplary embodiments of an invention may now be described in detail. Where the various figures may describe embodiments sharing various common elements and features with other embodiments, similar elements and features are given the same reference numerals and redundant description thereof may be omitted below.

An exemplary embodiment as disclosed herein and further with reference generally toFIGS. 1A-7relates to high power density power shelves, as used for example in server systems to convert AC power to the required DC power at low voltage, high current of the servers. To reach high power densities, low profile 1U (˜40 mm) shelves are used in conjunction with high power density switching power supplies. The increased power requirements of server systems further require heavy copper bus bars to carry supply currents in the excess of 1500 A from such shelves.

An exemplary bus bar configuration as disclosed herein allows the output currents from each power supply unit in a low profile shelf assembly to be collected in such a way that minimal height in the shelf is used for the overall bus bar system, leaving enough space for other connections and, more importantly, leaving enough space for air to cool the power supply units in the shelf.

Referring first toFIG. 1A.1B and2, an exemplary embodiment of a power shelf assembly10includes a housing defining a low profile interior having a height of, e.g., 1U (corresponding to the standard height of one shelf in a power supply rack, about 44.5 mm). The assembly may further define one or more channels16to receive a like number of power supply units on a first end of the housing, and further is configured to receive a bus bar arrangement20on a second end.

As illustrated herein, the housing may be referred to as having a left side11, a right side12, a bottom13and a top defined by a lid14, but the associated perspective view is for illustrative purposes only and is not intended as limiting an arrangement or orientation of the assembly10. While a power shelf assembly10is generally described herein in the context of having an interior defined by an enclosure on all but one side, a power shelf assembly may within the scope of the present invention further encompass a power shelf of a single rack unit among many in, for example, a server rack having a stacked plurality of rack units, and without specific reference to a floor, lid or sides defining or otherwise requiring an enclosed interior. Indeed, an exemplary power shelf assembly10may within the scope of the present invention be generally defined with respect to a spatial configuration and orientation of a bus bar arrangement20as further disclosed herein, relative to one or more power supply units which may be received and coupled thereto. One of skill in the art may appreciate that the term “shelf” as used herein may include any element or combination of elements supporting required objects or components as disclosed herein, and may be shaped to be not only rectangular but potentially square, or even having curved contours at one or more edges.

The housing further may be configured with a number of external signal connections18(FIG. 2) disposed on a rear side of the assembly, or otherwise opposing the side configured to receive the power supply units.

Referring toFIG. 3, an embodiment of a bus bar arrangement20as disclosed herein is configured so as to occupy only a first (e.g., upper) portion of the respective end of the power shelf assembly10. A first bus bar22may extend substantially across the power shelf assembly and in parallel with the bottom13and top14of the assembly10. A second bus bar24also extends along the same plane and may be mounted directly behind the first bus bar22, wherein a substantially identical height profile of the low profile shelf assembly is occupied by the bus bars.

In an embodiment, the bus bars22,24may be substantially rectangular copper or aluminum bus bars of the same size, collectively occupying 50% or less of the available height (i.e., as defined between the bottom and top of the interior).

A first set of bus bar pins28is coupled to the first bus bar22and extends in parallel with the bottom and top planes of the assembly toward the channels16for direct coupling with any associated power supply units. A second set of bus bar pins26is coupled to the second bus bar24and extends in parallel with the first set of pins28, wherein a single row of pins26,28extends for electrical coupling with the power supply units.

The first set of pins may collectively differ in length from the second set of pins, either based on structural requirements for the power supply units to be implemented, or to implement a specific contact sequence when a power supply is plugged in or out or otherwise simply to facilitate visual distinction between the respective pins by technicians. In various embodiments, however, the various pins may have substantially identical cross-sectional shapes and sizes.

One or more coupling devices may further be provided for coupling each bus bar22,24to the assembly10and/or external connections thereto, including for example but not limited to respective brackets, fasteners, hinges, rails and the like.

Referring now toFIGS. 4, 5A, 5B and 5C, in one embodiment the second set of pins26extends from the second bus bar24through corresponding apertures30in the first bus bar22and accordingly protrudes the first bus bar22and toward the power supply units. In an embodiment, an insulating material32is provided about at least the second set of pins26with respect to at least the corresponding apertures in the first bus bar22, wherein electrical short circuits may be avoided.

In a particular example, and by further reference toFIG. 6, the assembly10as described may include, e.g., six power supply units36each providing 3 kW of power at an output voltage of, e.g., 12V. This results in a total output current of 6×250 A=1500 A. The overall height of the low profile shelf10, as previously noted, is one rack unit (i.e., 1U or ˜40 mm). A copper bus bar22,24conducting 1500 A of current without generating excessive losses should not be loaded with more than ˜3 A per mm2cross section. This results in a required bus bar cross section of at least 500 mm2. With the proposed arrangement, a bus bar of 20×25 mm can be selected, at least theoretically leaving the aforementioned >50% of the shelf cross section for air flow40through the shelf, as may for example be generated or otherwise facilitated by convection cooling or forced-air cooling.

In various embodiments a cooling mechanism may be provided in the form of, for example, cooling fans38associated with power supply units36themselves, which may be oriented to regulate air flow in any of one or more directions. In other embodiments, cooling may be facilitated from outside of the assembly and further via the air channel proximate the bus bars, as well as air intakes and exhaust portions associated with the assembly housing and the power supply unit.

In another example, and by reference toFIG. 7, the space between the bus bar configuration20and the floor13of the assembly10may further be implemented for the placement of additional circuit boards42or other electrical components. This circuitry42may provide, for example, interconnects between external connectors18on the shelf10and the various power supply units36, for electrical signals or even the AC (or DC) input power to the power supply units. The cooling air flow40may in this example further provide cooling to electrical intermediary connections or other electrical components as may be desirably provided on the printed circuit board42.

Throughout the specification and claims, the following terms take at least the meanings explicitly associated herein, unless the context dictates otherwise. The meanings identified below do not necessarily limit the terms, but merely provide illustrative examples for the terms. The meaning of “a,” “an,” and “the” may include plural references, and the meaning of “in” may include “in” and “on.” The phrase “in one embodiment,” as used herein does not necessarily refer to the same embodiment, although it may.

The term “coupled” means at least either a direct electrical connection between the connected items or an indirect connection through one or more passive or active intermediary devices.

Conditional language used herein, such as, among others, “can,” “might,” “may,” “e.g.,” and the like, unless specifically stated otherwise, or otherwise understood within the context as used, is generally intended to convey that certain embodiments include, while other embodiments do not include, certain features, elements and/or states.

The previous detailed description has been provided for the purposes of illustration and description. Thus, although there have been described particular embodiments of a new and useful invention, it is not intended that such references be construed as limitations upon the scope of this invention except as set forth in the following claims.