Abstract:
A device is presented having at least one power supply. The power supply is connected to a power supply fan. A first power source terminal is connected to the at least one power supply. A second power source terminal is connected to the at least one power supply. The power supply fan is powered from a source external to the at least one power supply.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates power supply fans, and more particularly to providing control and power for power supply fans. 
     2. Description of the Related Art 
     As electronic devices, such as microprocessors, central processing units (CPUs), servers, and other similar types of electronic components become faster and are reduced in size, power consumed within the system per unit volume (power density) increases dramatically. Therefore, it is essential to dissipate the heat generated by electronic components within the system during its operation to keep the electronic components within their normal operating temperature ranges. If the electronic components operate outside of their operating temperature ranges, the life span of the electronic components will be reduced or fail immediately. 
     One effective technique for dissipating the heat from electronic components, such as a power supply, is to provide an internal fan, or fan assembly, to directly apply a relatively high-velocity air stream across the surface of the electronic components. By forcing high-velocity air across the surface of the internal component(s), the conductive heat transfer coefficient for the surface of the internal electronic components is increased, thus increasing the convection cooling. 
     Current technology for power supplies has the power supply providing power internally for the internal or attached fans. Power supplies can fail if the cooling fan fails, leading to overheating of electronic components, or the electronic components can fail themselves. If the power supply fails, it follows that the power supply fan shuts off since there will not be any power supplied to sustain operation of the fan. 
     In many systems today, such as server systems, power is supplied to internal components from alternate sources besides the power supply. Moreover, in these systems, the power supply fans may be used to cool other components besides the power supply itself. When a power supply fan fails due to the power supply failing, the internal system&#39;s components may reach an over temperature situation. In the over temperature situation, components can be exposed to harm due to exceeding the operating temperature range. Further, if the system uses other fans, these fans may need to increase their speed in order to makeup for the loss of the power supply fan. In this case, acoustical noise is increased due to the higher fan speed of the system fans. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The invention is illustrated by way of example and not by way of limitation in the figures of the accompanying drawings in which like references indicate similar elements. It should be noted that references to “an” or “one” embodiment in this disclosure are not necessarily to the same embodiment, and such references mean at least one. 
     FIG. 1 illustrates a typical set of power supply fans each internally powering a power supply fan. 
     FIG. 2 illustrates an embodiment including system level power for power supply fans. 
     FIG. 3 illustrates an embodiment including system level power and speed control for power supply fans. 
     FIG. 4 illustrates an embodiment including a switch to provide system level power and speed control for a system. 
     FIG. 5 illustrates an embodiment including a power supply power bus for providing shared power to power supply fans. 
     FIG. 6 illustrates an embodiment including a power supply power and control bus for providing shared power to power supply fans. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The invention generally relates to providing external power to power supply fans. Referring to the figures, exemplary embodiments of the invention will now be described. The exemplary embodiments are provided to illustrate the invention and should not be construed as limiting the scope of the invention. 
     FIG. 1 illustrates a typical set of power supplies that are used for supplying power to a device or system. Power supply set  100  includes power supply  1   110 , power supply  2   120  and power supply N  130 . Each power supply in power supply set  100  includes an internal or attached power supply fan. Power supply  1   110  is coupled with power supply fan  140 , power supply  2   120  is coupled with power supply fan  135  and power supply N  130  is coupled with power supply fan  150 . Each power supply in power supply set  100  has positive voltage connector  180  and negative voltage connector  175 . Positive voltage connector  180  and negative voltage connector  175  supply power to each of the power supply fans (power supply fan  140 ,  145  and  150 ). The power supplied to each of the power supply fans in power supply set  100  is internal to the specific power supply, i.e. power is supplied directly from the power supply itself. Each power supply fan has its speed controlled by an internal fan speed controller within each power supply (denoted as  170  in power supply  1   110 , power supply  2   120  and power supply N  130  illustrated in FIG.  1 ). 
     Each power supply fan in power supply set  100  is used to provide cooling for the power supply itself and may also provide cooling for additional electronic components. As illustrated in FIG. 100, power supply  1   110  is associated with electronic component  155 , power supply  2   145  is associated with electronic device  160  and power supply N  130  is associated with electronic component  165 . The associated electronic component ( 155 ,  160  and  165 ) may be a device such as discrete power converter, etc. When one power supply in power supply set  100  fails, the associated fan (power supply fans  140 ,  145  and  150 ) also fails since they are powered directly by the associated power supply. Since an associated electronic device (electronic device  155 ,  160  and  165 ) relies on cooling from the fan powered by its associated power supply, an overheating situation can result from the loss of fan cooling due to power supply failure. 
     FIG. 2 illustrates an embodiment including system level supplied power for each power supply fan in a set of power supplies. Power supply set  200  includes power supply  1   210 , power supply  2   220  and power supply N  230 . Power supply  1   210 , power supply  2   220  and power supply N  230  each include positive voltage connector  270 , negative voltage connector  260  and internal fan speed controller  205 . Internal fan speed controller  205  controls fan motor speed. Fan speed controller  205  uses a known technique to control fan speed, such as pulse width modulation (PWM), voltage/resistance variation, thermal speed control, etc. Fan speed controller  205  can also use a tachometer or other known techniques for fan rotation velocity feedback. 
     In power supply set  200 , power is provided for fans  140 ,  145  and  150  via positive system voltage source  240  and negative system voltage source  250 . One should note that a single positive system voltage source can be used if grounding is provided for by another source, such as by each of the power supplies, a common ground, etc. By using system level power to supply fans  140 ,  145  and  150  with power, if any of the power supplies in power supply set  200  fail, the associated power supply fan remains provided with power. Therefore, each power supply fan within power supply set  200  can each still provide fan cooling to an associated electronic device or other electronic components situated within the vicinity of the failed power supply. 
     Each power supply in power supply set  200  control the associated fan&#39;s speed via fan speed controller  205 . In the case of power supply failure, power supply fan speed controller  205  will not function. Therefore, in one embodiment each power supply in power supply set  200  maintains an intermediate setting (minimum voltage required for an intermediate value; e.g., 2.5 Volts when the range is 0 to 5 Volts) for fan speed in the case of power supply failure. The intermediate fan speed setting can be preset by a device, such as a dip setting, potentiometer setting or electronic connection. When an associated fan (e.g., fan  140 ,  145  and  150 ) senses that fan speed controller  205  is failed (e.g., senses a failed condition such as zero volts) the fan speed will be set to this intermediate value and remain steady at the intermediate fan speed value in order to cool any associated electronic components or electronic component situated in the vicinity of the fan. 
     FIG. 3 illustrates an embodiment including system level power and speed control for power supply fans in a power supply set. In this embodiment, power supply fans in power supply set  300  are supplied with system level power from positive system voltage source  240  and negative system voltage source  250 . Positive system voltage source  240  and negative system voltage source  250  reside on/in a system, such as a server system. Power supply fan speed is controlled by both internal power supply fan speed controller  305  and/or system fan speed controller  340 , which is coupled with fan speed controller terminal  350 . Internal fan speed controller  305  and system fan speed controller  340  control fan motor speed. Fan speed controller  305  and system fan speed controller  340  use a known technique to control fan speed, such as pulse width modulation (PWM), voltage/resistance variation, thermal speed control, etc. Fan speed controller  305  and system fan speed controller  340  can also use a tachometer or other known techniques for fan rotation velocity feedback. 
     Internal power supply fan speed controller  305  works with system fan speed controller  340  to control an associated fan (power supply fan  140 ,  145  and  150 ). Internal power supply fan speed controller  305  can increase fan speed over the level set by system fan speed controller  340 , but can not lower the set fan speed set by system fan speed controller  340 . 
     If a power supply fails in power supply set  300 , since each power supply fan in power supply set  300  has power supplied by a source external to the failed power supply, the power supply fan remains operating to provide cooling to associated electronic components or electronic components situated in the vicinity of the power supply. In this embodiment, upon failure of the power supply, fan speed is controlled by system fan speed controller  340 . One should note that while FIG. 3 illustrates a common connection for positive system voltage source  240 , negative system voltage source  250  and system fan speed controller  340 , that individual connections to each power supply in power supply set  300  can be used instead of common connections. 
     FIG. 4 illustrates an embodiment including a switch to select power control and fan speed control between two sources for a power supply fan. Each power supply in power supply set  400  includes a switch  450  to switch between system power provided by positive system voltage source  240  and negative system voltage source  250  and internal power supplied from the power supply to a positive terminal  180  and a negative terminal  175 . Also, power supply fan speed control can be switched between internal power supply fan speed control  470  and system fan speed control  340  (connected to fan speed controller terminal  350 ) via switch  450 . 
     Switch  450 , upon sensing a power supply failing (e.g., loss of power), switches over to system power supplied by positive system voltage source  240  and negative system voltage source  250 , and switches fan speed control to fan speed controller  340 . One should note that switch  450  can contain separate switches, separate coupled switches, or a single switch. Also, switch  450  can use any switch technology, such as transistor, electronic, etc. 
     In one embodiment, switch  450  senses voltage and switches over to system control upon falling below a necessary voltage threshold to power a power supply fan, such as a 12-volt threshold. In another embodiment, switch  450  can sense a current threshold from current supplied internal to a power supply, such as 1 amp. Once the internal power supply&#39;s current falls below the current threshold, switch  450  switches over to system power and fan speed control. In still another embodiment, switch  450  has a thermal sensor and switches over to system control once it senses a certain temperature threshold that can be user adjusted. In this embodiment, the associated power supply can be turned off (via switch  450 ) and still be afforded cooling by the associated power supply fan operating under system control. An alarm or signal can also be sounded/transmitted from switch  450  to the system via a transmission medium, such as a signal bus or wire, to alarm/inform of a temperature problem at the power supply. This would allow maintenance to replace or repair the power supply that is overheating. 
     By using switch  450 , if the power supplies in power supply set  400  fail, power supply fans  140 ,  145  and  150  remain operating via system provided power and system provided fan speed control. Therefore, electronic components relying on cooling by power supply fans (such as electronic component  155 ,  160  and  165 ) can avoid damage from an overheating condition. Further, since the power supply&#39;s internal or attached fan remains operating in a failed power supply, other fans within the system can remain at their current fan speed. Thus, acoustical noise is reduced by not having to increase fan speed of remaining power supply fans in order to make up a cooling loss from a failed power supply and its associated fan. 
     In one embodiment, an electrical connector to connect negative terminal  175 , positive terminal  180  and fan speed control  470  connects a power supply to a power supply fan (e.g., power supply fan  140 ,  145  and  150 ) in power supply set  400 . This power supply can be disconnected, which will switch fan power over to negative voltage terminal  260  and positive voltage terminal  270 . Also, fan speed control is switched to fan speed controller terminal  350 . Therefore, this embodiment allows maintenance of a power supply without having to shutdown a complete system. Also, fan cooling is continued while the power supply is being replaced. Thus, in cases such as “hot” swapping or replacing failed power supplies, cooling efficiency is not reduced. Further, acoustical noise is not increased since other fans need not increase fan speed to compromise for a loss of a power supply fan. 
     FIG. 5 illustrates an embodiment having a power supply power bus for providing shared power to power supply fans. In this embodiment, each power supply (power supply  1   520 , power supply  2   530  and power supply N  540 ) in power supply set  500  has positive voltage terminal  270  and negative voltage terminal  260  coupled with a power supply bus  510 . Each power supply in power supply set  500  also supplies power internally to an associated power supply fan (power supply fan  140 ,  145  and  150 ). Positive voltage terminal  270  and negative voltage terminal  260  are coupled in parallel with negative terminal  175  and positive terminal  180  for each power supply in power supply set  500 . Therefore, if a power supply in power supply set  500  fails, (i.e., loss of internal power to provide to a power supply fan), the associated power supply fan will remain in operation by receiving necessary power from power bus  510 . 
     Since every power supply in a power supply set (e.g., power supply  1   520 , power supply  2   530  and power supply fan  540  within power supply set  500 ) has its internal power source coupled with positive voltage terminal  270  and negative voltage terminal  260  in parallel, and each power supply has its positive voltage terminal  270  and negative voltage terminal  260  coupled in parallel with power supply bus  510 , if one power supply within power supply set  500  fails, the non-failing power supplies will have their power supply fans provided with sufficient power to continue operating. 
     In one embodiment, each power supply in power supply set  500  controls an associated fan&#39;s speed via fan speed controller  570 . In the case of power supply failure, power supply fan speed controller  570  will not function. Therefore, in one embodiment each power supply in power supply set  500  maintains an intermediate setting (minimum voltage required for an intermediate value; e.g., 2.5 Volts when the range is 0 to 5 Volts) for fan speed in the case of power supply failure. The intermediate fan speed setting can be preset by a device, such as a dip setting, potentiometer setting or electronic connection. When an associated fan (e.g., fan  140 ,  145  and  150 ) senses that fan speed controller  570  is failed (e.g., senses a failed condition such as zero volts) the fan speed will be set to this intermediate value and remain steady at the intermediate fan speed value in order to provide cooling to any associated electronic components or electronic component situated in the vicinity of the fan. 
     In one embodiment, fan speed control is provided by system fan speed controller  340 . In this embodiment, if a power supply fails, not only will the power supply fan be provided with power from power supply bus  510 , but each power supply fan will also be provided with fan speed control from system fan speed controller  340 . In one embodiment, internal fan speed control  570  has the capability to increase a power supply fan&#39;s fan speed, but cannot decrease fan speed set by system fan speed controller  340 . 
     FIG. 6 illustrates an embodiment having a power supply power and control bus for providing shared power to power supply fans. In this embodiment, each power supply (power supply  1   620 , power supply  2   630  and power supply N  640 ) in power supply set  600  has positive voltage terminal  270  and negative voltage terminal  260  coupled with power supply power and control bus  610 . Each power supply in power supply set  600  also supplies power internally to an associated power supply fan (power supply fan  140 ,  145  and  150 ). Positive voltage terminal  270  and negative voltage terminal  260  are coupled in parallel with negative terminal  175  and positive terminal  180  for each power supply in power supply set  600 . Therefore, if a power supply in power supply set  600  fails, (i.e., loss of internal power to provide to a power supply fan), the associated power supply fan will remain in operation by receiving necessary power from power supply power and control bus  610 . 
     Since every power supply in a power supply set (e.g., power supply  1   620 , power supply  2   630  and power supply fan  640  within power supply set  600 ) has its internal power source coupled with positive voltage terminal  270  and negative voltage terminal  260  in parallel, and each power supply has its positive voltage terminal  270  and negative voltage terminal  260  coupled in parallel with power supply power and control bus  610 , if one power supply within power supply set  600  fails, the non-failing power supplies will have their power supply fans provided with sufficient power to continue operating. 
     In one embodiment, each power supply in power supply set  600  controls an associated fan&#39;s speed via fan speed controller  570 . In the case of power supply failure, power supply fan speed controller  570  will not function. Therefore, each power supply in power supply set  600  has power supply fan speed controller  670  coupled in parallel to power supply power and control bus  610 , and power supply fan speed controller  570 . When an associated fan (e.g., fan  140 ,  145  and  150 ) senses that fan speed controller  570  is failed (e.g., senses a failed condition such as zero volts) the fan speed will be set by a voltage supplied by power supply power and control but  610  in order to provide cooling to any associated electronic components or electronic component situated in the vicinity of the fan. Since fan speed control voltage is in a specific range (e.g., between 0 and 5 Volts), fan speed controller  670  sets fan speed according to the average voltage value from non-failed fan speed controllers  570  in the power supplies coupled to power supply power and control bus  610 . 
     In one embodiment, each power supply in power supply set  600  maintains an intermediate setting (minimum voltage required for an intermediate value; e.g., 2.5 Volts when the range is 0 to 5 Volts for fan speed in the case of complete power supply failure (i.e., all power supplies in power supply set  600  fail). The intermediate fan speed setting can be preset by a device, such as a dip setting, potentiometer setting or electronic connection. When an associated fan (e.g., fan  140 ,  145  and  150 ) senses that fan speed controller  670  is failed (e.g., senses all fan speed controllers are failed) the fan speed will be set to this intermediate value and remain steady at the intermediate fan speed value in order to provide cooling to any associated electronic components or electronic component situated in the vicinity of the fan. 
     While certain exemplary embodiments have been described and shown in the accompanying drawings, it is to be understood that such embodiments are merely illustrative of and not restrictive on the broad invention, and that this invention not be limited to the specific constructions and arrangements shown and described, since various other modifications may occur to those ordinarily skilled in the art.