Patent Application
20080306633
The present application relates to cooling systems. Specifically, the present application relates to an optimized power and airflow multistage fan system.
Cooling systems are used in many areas of everyday life, from cooling our automobiles and homes to cooling the electronic devices in our automobiles and homes. Many cooling systems operate in two modes, on and off. When cooling is needed, the system turns on. When cooling is no longer needed, the system turns off. These systems can be inefficient because they oftentimes over cool thereby using too much power to perform the needed cooling. In addition, these systems are noticeably loud when on and get louder with increased power. Other cooling systems operate with respect to the temperature of the object to be cooled. In other words, when object of the cooling cools down, the cooling system slows down or stops. Then, when the object of the cooling heats up, the cooling system speeds up. This type of cooling system may be more efficient than an on/off cooling system that operates in two modes, but, sometimes these systems overcool the object of the cooling and therefore, there is room for improvement in the art. Thus, it is desirable to improve efficiency and reduce unnecessary noise of cooling systems.
A system and method of adjusting the operation of a cooling device is provided. An embodiment of the system includes a cooling device, an input sensory device, a control algorithm, and a controller that adjusts operation of the cooling device based on the control algorithm. An embodiment of the control algorithm approximates a plurality of substantially linear cooling curves to relate to portions of a non-linear cooling curve for the cooling device, the algorithm selects a selected cooling curve from the plurality of substantially linear cooling curves based on an input from the sensory device.
For purposes of this disclosure, an IHS includes any instrumentality or aggregate of instrumentalities operable to compute, classify, process, transmit, receive, retrieve, originate, switch, store, display, manifest, detect, record, reproduce, handle, or utilize any form of information, intelligence, or data for business, scientific, control, or other purposes. For example, an IHS may be a personal computer, a network storage device, or any other suitable device and may vary in size, shape, performance, functionality, and price. The IHS may include random access memory (RAM), one or more processing resources such as a central processing unit (CPU) or hardware or software control logic, read only memory (ROM), and/or other types of nonvolatile memory. Additional components of the IHS may include one or more disk drives, one or more network ports for communicating with external devices as well as various input and output (I/C) devices, such as a keyboard, a mouse, and a video display. The IHS may also include one or more buses operable to transmit communications between the various hardware components.
Other resources can also be coupled to the system through the memory I/O hub 104 using a data bus, including an optical drive 114 or other removable-media drive, one or more hard disk drives 116, one or more network interfaces 118, one or more Universal Serial Bus (USB) ports 120, and a super I/O controller 122 to provide access to user input devices 124, etc. It is also becoming feasible to use solid state drives (SSDs) 126 in place of, or in addition to main memory 108 and/or a hard disk drive 116.
Not all IHSs 100 include each of the components shown in
Generally, when the ambient temperature increases or decreases, as sensed by the ambient temperature sensor 130, the BMC 128 linearly adjusts power to the cooling fan 132 at a pre-determined rate up to and down to pre-set cutoff levels.
In other words, using the cooling curve 144, the fan 132 will operate at a variable power/output level along a ramped portion 145 of the cooling curve. As an example, an ambient temperature of 25 C corresponds to a fan speed of 50% of full speed to obtain the desired cooling at that temperature. When the temperature increases, as shown along a bottom axis of
Turning now to
The method 150 begins in step 151 where the BMC 128 on the motherboard 101 of the IHS 100 reads an input temperature from the ambient temperature sensor 130. For this example, the ambient temperature of 25 C is used. In other embodiments (not shown), device temperature, device power, or any other feature may be read and used instead of ambient temperature to control the interpolation using the control curves. In step 152, the BMC 128 interpolates a first output value, shown at 50% full fan speed at 155 using the first cooling curve 154. This output is stored at step 153 for comparing with interpolated values using other cooling curves. In step 156, the BMC 128 interpolates a second output value, shown at 61% full fan speed at 159 using the second cooling curve 158. This output is stored at step 157 for comparing with interpolated values using other cooling curves. Next, in step 160, the BMC 128 interpolates a third output value, shown at 58% full fan speed at 163 using the third cooling curve 162. This output is stored at step 161 for comparing with interpolated values using other cooling curves. Once all of the output values have been interpolated using all of the desired cooling curves 154, 158, and 162, the BMC 128 in step 166, in this case, determines the highest value fan output needed for optimal cooling. The highest value is used here so that the object of the cooling, e.g. the IHS 100 hardware, receives enough cooling to prevent overheating. The composite non-linear cooling curve 167 is derived from the substantially linear portions 155, 159, and 163 of the respective cooling curves 154, 158, and 162.
In practice, the non-linear cooling curves 167 and 168 may be derived from temperature testing or thermal development of the subject of the cooling, such as the IHS 100. The method 176 shows one embodiment for optimizing a cooling system to use existing linear software or firmware to control system fans even though the optimized cooling curves 167, 168 are not linear. In step 178, the object of the cooling, here an IHS 100, is thermally tested to determine fan speeds for optimally cooling the IHS 100 at a full range of ambient temperatures. Then, in step 180 optimum cooling curves are calculated or otherwise derived from the thermal testing of step 178. The resulting cooling curve may resemble the non-linear curves 167 and 168. Next, in step 182, a plurality of substantially linear cooling curves approximately following or relating to portions of the non-linear cooling curve are derived from the non-linear curve. The plurality of substantially linear cooling curves may resemble the cooling curves 154, 158, and 162. Step 184 associates a fan speed, here a percentage of full speed, with the substantially linear cooling curves to create pre-determined outputs to control the fan 132 for given ambient temperatures. Continuing on to step 186, the method 176 has the object of the cooling or here, the BMC 128 measure the ambient temperature (or any other desired input) using the temperature sensor 130. Step 188 then selects a preferred linear cooling curve for the measured input. As indicated above, the selection of a preferred cooling curve may be the highest value, the lowest value, or have any other desired requirement. Finally, step 190 operates the cooling fan 132 at the necessary speed relating to the preferred substantially linear cooling curve for the measured input. As a result, optimum power, airflow, and noise level can be obtained for multiple temperatures using a non-linear cooling curve, while only needing software/firmware that is only capable of controlling the fan 132 linearly.
Steps 178-184 are generally performed by the system developer during system development. The remaining steps, 186-190, in method 176 are generally performed by a user of the method and not necessarily by the developer of the system. Thus, different individuals or different entities may practice different portions of the method 176. It is also understood that other factors or considerations may influence control of the cooling system in addition to ambient temperature.
In summary, the present disclosure provides a system and method to utilize common linear BMC Firmware algorithms to allow an optimized non-linear fan control without the need to implement new, complex, and computation-intensive non-linear algorithms. This method and system involves creating multiple simple linear fan control curves, and overlaying them in a way to produce a piece-wise, multi-stage linear approximation of a true non-linear curve. One embodiment of this method allows existing linear BMC fan control algorithms to provide non-linear fan control without requiring modification of the existing source code. The BMC 128 computes each linear fan control curve independently, and in one embodiment, retains the highest fan output valve after analyzing each linear curve. The resultant effect is that the BMC 128 produces a non-linear output from a set of linear input curves.
By overlaying non-linear curves, a fan speed response to ambient temperature can be optimized across a full range of supported ambient temperatures, such as 10-35 C. Present state of the art fan speed temperature responses for exemplary IHS servers are linearly curve fitted to ambient temperatures of approximately 25-35 C. Fan speeds are static at temperatures below 25 C. Fan speeds could be reduced below 25 C (with data center ambient temperatures of 17-23 C typical) with system airflow and power reductions, however, with a linear fan speed response, component temperatures would be exceeded at lower ambient temperature due to the non-linear mapping of fan speeds and component cooling. Likewise, due to the linear curve fit of fan speed and ambient temperature, components are often overcooled at high ambient temperatures at the expense of system power.
An advantage over existing multistage fan response to ambient temperatures has been developed and implemented in the Dell™, PowerEdge™, 6950 server. An embodiment of the multistage fan response method allows for linear ramp rates over different ranges of ambient conditions. By utilizing the multistage fan response method airflow savings of for example, almost 20% may be realized as well as a fan power savings of, for example, approximately 34%.
Although illustrative embodiments have been shown and described, a wide range of modification, change and substitution is contemplated in the foregoing disclosure and in some instances, some features of the embodiments may be employed without a corresponding use of other features. Accordingly, it is appropriate that the appended claims be construed broadly and in a manner consistent with the scope of the embodiments disclosed herein.
