Patent Publication Number: US-2022240415-A1

Title: Fan control method

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims the benefit of priority of Taiwan Patent Application No. TW110102874, filed on Jan. 26, 2021. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of the specification. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The disclosure relates to a fan control method, and in particular, to a fan control method for heat dissipation of an electronic device. 
     Description of the Related Art 
     A traditional fan control method for heat dissipation of an electronic device takes temperature data of an electronic element as a main reference index for controlling rotational speed of a fan. The rotational speed of the fan is correspondingly changed with variations of temperatures of the electronic element. 
     However, as the temperature of the electronic element, such as a central processing unit changes rapidly, performing different operation applications generates different temperature rising and falling. One traditional control method reacting rapidly to the temperature variation makes large fluctuation of the rotational speed of the fan. It generates noise easily, and causes poor use experience. Another traditional control method reacting slowly to the temperature variation solves the problem of noise, but when the electronic element operates with high loads, it is easy to cause the problem of slow response of heat dissipation control. 
     BRIEF SUMMARY OF THE INVENTION 
     The disclosure provides a fan control method, applied to an electronic device. The electronic device includes a fan and a setting unit, the setting unit having a plurality of setting values, and each setting value being corresponding to a sampling number. The fan control method includes: continuously detecting a temperature of a heat source to obtain a plurality of temperature values; selecting one of the plurality of setting values based on variations of the temperature values; acquiring a value set from the temperature values based on the sampling number corresponding to the selected setting value, and generating an updated temperature value based on the value set; and controlling rotation of the fan based on the updated temperature value. 
     By means of the fan control method and the fan control system of the disclosure, the sampling number is dynamically adjusted based on the sampling temperature to adapt to different load change scenarios, which not only conforms to heat dissipation requirements, but also improves the auditory perception of users. In addition, the fan control method and fan control system of the disclosure also change a reaction speed of the fan to a temperature value change in response to changes in loads, so that the fan control is adapted to different system application conditions. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic block diagram showing an embodiment of a fan control system according to the disclosure. 
         FIG. 2  is a flowchart showing a first embodiment of a fan control method according to the disclosure. 
         FIG. 3  shows a fan control graph. 
         FIG. 4  is a flowchart showing a second embodiment of the fan control method according to the disclosure. 
         FIG. 5  is a flowchart showing a third embodiment of the fan control method according to the disclosure. 
         FIG. 6  is a flowchart showing a fourth embodiment of the fan control method according to the disclosure. 
         FIG. 7  is a flowchart showing a fifth embodiment of the fan control method according to the disclosure. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Specific embodiments of the disclosure are described in more detail below with reference to the schematic diagrams. Advantages and features of the disclosure will be clearer based on the following descriptions and claims. It is to be noted that all the figures are in a very simple form and in an inaccurate proportion, and are merely intended to assist description of the purpose of the embodiments of the disclosure conveniently and clearly. 
       FIG. 1  is a schematic block diagram showing an embodiment of a fan control system according to the disclosure. The fan control system  10  is disposed in an electronic device, such as a computer host and a notebook computer that needs to be cooled by using a fan. The fan control system  10  is configured to detect a temperature of a heat source  20  to control a rotational speed of a fan  30 . The heat source  20  is a wafer, a mainboard, or other electronic elements that generate heat during operation. As shown in the figure, the fan control system  10  includes a temperature detection unit  12 , a control unit  14 , a setting unit  15 , a memory  16 , and a driving unit  18 . 
     The temperature detection unit  12  is configured to continuously detect the temperature of the heat source  20  to obtain a plurality of temperature values S1, S2, . . . , Sn-1, and Sn. In one embodiment, the temperature detection unit  12  detects the temperature of the heat source  20  every preset time to obtain a temperature value, for example, the temperature of the heat source  20  is detected every one second. 
     The temperature values S1, S2, . . . , Sn-1, and Sn include a current temperature value (that is, a latest temperature value Sn) and a plurality of previous temperature values (that is, temperature values S1, S2, . . . , and Sn-1 detected prior to the current temperature value). 
     The control unit  14  obtains temperature values S1, S2, . . . , Sn-1, and Sn from the temperature detection unit  12 , and selects one of a plurality of setting values based on variations of the temperature values S1, S2, . . . , Sn-1, and Sn. The setting values correspond to different sampling numbers PN. The setting unit  15  includes a plurality of setting values for the control unit  14  to select. 
     In one embodiment, the setting values of the setting unit  15  are preset when a product leaves a factory. In one embodiment, the setting unit  15  also has a memory unit to store the setting values, which is not limited thereto. In one embodiment, the setting unit  15  directly stores the sampling number PN as well. 
     The control unit  14  also acquires a value set G1={Sn-m, . . . , and Sn-1} from the temperature values S1, S2, . . . , Sn-1, and Sn based on the sampling number PN (such as a positive integer m) corresponding to the selected setting value, and generates an updated temperature value Sn′ based on the value set G1. 
     After the updated temperature value Sn′ is generated, the control unit  14  obtains a fan control graph from the memory  16 , maps a corresponding target rotational speed in the fan control graph based on the updated temperature value Sn′, and drives the fan  30  to rotate by means of the driving unit  18  based on the target rotational speed. The fan control graph is described in more detail in  FIG. 3  of the disclosure. The operation details of the control unit  14  are described in the following paragraph corresponding to a fan control method. 
       FIG. 2  is a flowchart showing a first embodiment of a fan control method according to the disclosure. The fan control method is applied to an electronic device. The electronic device includes a fan and a setting unit, the setting unit includes a plurality of setting values, and each setting value corresponds to a different sampling number. As shown in the figure, the fan control method includes the following steps. 
     Firstly, as described in step S 110 , a temperature of a heat source  20  is continuously detected to obtain a plurality of temperature values S1, S2, . . . , Sn-1, and Sn. The temperature values S1, S2, . . . , Sn-1, and Sn include a current temperature value (that is, a temperature value Sn) and a plurality of previous temperature values (that is, the temperature values S1, S2, . . . , and Sn-1). 
     Then, the fan control method includes selecting one of a plurality of setting values based on variations of the temperature values S1, S2, . . . , Sn-1, and Sn. The selection logic is as follows. When the variation between the previous temperature value and the current temperature value is rapid, a setting value of a sampling number PN corresponding to a smaller value tends to be selected. 
     When the variation between the previous temperature value and the current temperature value is gentle, a setting value of the sampling number PN corresponding to a larger value tends to be selected. When the temperature value shows a decreasing temperature change, the setting value of the sampling number PN corresponding to the larger value tends to be selected. 
     In one embodiment of the disclosure, as described in step S 120 , firstly, a reference value set G0 is acquired from the temperature values S1, S2, . . . , Sn-1, and Sn based on a preset number i, and a reference average value A0 of the reference value set G0 is calculated. A temperature value in the reference value set G0 is a latest temperature value in the previous temperature values. A number of the temperature values in the reference value set G0 is the preset number i. 
     In one embodiment, the preset number i is one of the sampling numbers PN. In one embodiment, the preset number i is the sampling number PN used for previously controlling a fan  30  to rotate. In an embodiment, assuming the temperature values detected in step S 110  are S 1 , S 2 , . . . , Sn- 1 , and Sn, Sn is the current temperature value, and S1, S2, . . . , and Sn-1 are the previous temperature values. When the sampling number PN used for previously controlling the fan  30  to rotate is 5, in step S 120 , an average of the temperature values Sn-5, Sn-4, . . . , and Sn-1 is calculated as the reference average value A0. 
     Next, as described in step S 130 , a difference d (d=Sn−A0) between the current temperature value Sn and the reference average value A0 is calculated. The difference d shows variations of the temperature values. When the difference d is relatively large, it indicates that the current temperature varies rapidly. When the difference d is relatively small, it indicates that the current temperature maintains stable. When the difference d is negative, it indicates that the temperatures are decreased progressively. 
     Then, as described in step S 140 , one of the plurality of setting values is selected based on the difference d. The selection logic is as follows. When the difference d is relatively large, a setting value of a sampling number PN corresponding to a smaller value tends to be selected. When the difference d is relatively small, a setting value of the sampling number PN corresponding to a larger value tends to be selected. When the difference d is negative, the setting value of the sampling number PN corresponding to the larger value tends to be selected. Various different embodiments of step S 140  are described in more detail in the following paragraphs. 
     Then, as described in step S 150 , a value set G1={Sn-m, . . . , and Sn-1} is acquired from the temperature values S1, S2, . . . , Sn-1, and Sn based on the sampling number PN (such as a positive integer m) corresponding to the selected setting value, and an updated temperature value Sn′ is generated based on the value set G1. In one embodiment, the updated temperature value Sn′ is an average value of the value set G1. In an embodiment, when the sampling number corresponding to the selected setting value is  10 , in step S 150 , temperature values Sn-10, Sn-9, . . . , and Sn-1 are acquired as the value set G1, and the average value A1 of the temperature values Sn-10, Sn-9, . . . , and Sn-1 is calculated as the updated temperature value Sn′. 
     Then, as described in step S 160 , the fan  30  is controlled, based on the updated temperature value Sn′, to rotate. In one embodiment, in step S 160 , a target rotational speed is mapped, based on the updated temperature value Sn′, in the fan control graph to control the fan  30  to rotate. Referring to  FIG. 3  as well,  FIG. 3  shows the fan control graph. As shown in the figure, a horizontal axis and a vertical axis of the fan control graph respectively represent temperatures (° C.) and rotational speeds (RPM) of a fan to show a correspondence between the temperature and the fan speed. A corresponding target rotational speed is found, based on a given temperature value, in the fan control graph to control the fan  30  to rotate. 
     Referring to  FIG. 1  as well, in one embodiment, step S 110  of the fan control method is performed by the temperature detection unit  12  and the control unit  14  in  FIG. 1 , steps S 120  to S 150  are performed by the control unit  14  in  FIG. 1 , and step S 160  is performed by the control unit  14  and the driving unit  18  in  FIG. 1 . The fan control graph is stored in the memory  16  in  FIG. 1 . 
     In steps S 120  to S 150  of the above embodiments, the current temperature value (that is, the temperature value Sn) is not included in the acquired reference value set G0 and value set G1, which is not limited thereto. In one embodiment, the current temperature value (that is, the temperature value Sn) is also included in the reference value set G0 and the value set G1 for calculation. In an embodiment, when the preset number i in step S 120  is 5, in step S 120 , the average value of temperature values Sn-4, Sn-3, Sn-1, and Sn is calculated as the reference average value 0. 
       FIG. 4  is a flowchart showing a second embodiment of the fan control method according to the disclosure. A main difference between this embodiment and the embodiment of  FIG. 2  lies in the step (corresponding to step S 140  of  FIG. 2 ) of selecting one of the plurality of setting values based on the difference d. Other steps of this embodiment are similar to the embodiment of  FIG. 2 , and details are not described herein. 
     Referring to  FIG. 1  as well, in this embodiment, the setting unit  15  presets a first temperature difference Td1 and a second temperature difference Td2, and sets three setting values respectively corresponding to a first sampling number PN1, a second sampling number PN2, and a third sampling number PN3. The first temperature difference Td1 is greater than the second temperature difference Td2, the first sampling number PN1 is less than the second sampling number PN2, and the second sampling number PN2 is less than the third sampling number PN3. 
     Carrying on with step S 130 , as described in step S 240 , when the difference d is greater than the first temperature difference Td1, a setting value corresponding to the first sampling number PN1 is selected. When the difference d is less than or equal to the first temperature difference Td1 and is greater than the second temperature difference Td2, a setting value corresponding to the second sampling number PN2 is selected. When the difference d is less than or equal to the second temperature difference Td2, a setting value corresponding to the third sampling number PN3 is selected. 
     The sampling number corresponding to the setting value selected in step S 240 , that is, the first sampling number PN1, the second sampling number PN2, or the third sampling number PN3, is used in step S 150  of  FIG. 2  to acquire the value set G1. 
       FIG. 5  is a flowchart showing a third embodiment of the fan control method according to the disclosure. A main difference between this embodiment and the embodiment of  FIG. 2  lies in the step (corresponding to step S 140  of  FIG. 2 ) of selecting one of the plurality of setting values based on the difference d. Other steps of this embodiment are similar to the embodiment of  FIG. 2 , and details are not described herein. 
     Referring to  FIG. 1  as well, in this embodiment, the setting unit  15  presets a first temperature difference Td1 and a second temperature difference Td2, and sets three setting values respectively corresponding to a first sampling number PN1, a second sampling number PN2′, and a third sampling number PN3. The first temperature difference Td1 is greater than the second temperature difference Td2, the first sampling number PN1 is less than the second sampling number PN2′, the second sampling number PN2′ is less than the third sampling number PN3, and the second sampling number PN2′ corresponds to a preset equation. In other words, the second sampling number PN2′ is calculated based on the difference d by using the preset equation. 
     Carrying on with step S 130 , as described in step S 340 , when the difference d is greater than the first temperature difference Td1, a setting value corresponding to the first sampling number PN1 is selected. When the difference d is less than or equal to the first temperature difference Td1 and is greater than the second temperature difference Td2, a setting value corresponding to the second sampling number PN2′ is selected. When the difference d is less than or equal to the second temperature difference Td2, a setting value corresponding to the third sampling number PN3 is selected. 
     The sampling number corresponding to the setting value selected in step S 340 , that is, the first sampling number PN1, the second sampling number PN2′, or the third sampling number PN3, is used in step S 150  of  FIG. 2  to acquire the value set G1. 
     Compared with the embodiment of  FIG. 4 , the second sampling number PN2 is a constant, but the second sampling number PN2′ of this embodiment varies with the difference d. In one embodiment, the preset equation includes a linear equation. In one embodiment, the linear equation is a negatively related linear equation. In other words, an increase in the difference d indicates a decrease in the second sampling number PN2′. 
       FIG. 6  is a flowchart showing a fourth embodiment of the fan control method according to the disclosure. A main difference between this embodiment and the embodiment of  FIG. 2  lies in the step (corresponding to step S 140  of  FIG. 2 ) of selecting one of the plurality of setting values based on the difference d. Other steps of this embodiment are similar to the embodiment of  FIG. 2 , and details are not described herein. 
     Referring to  FIG. 1  as well, in this embodiment, the setting unit  15  presets a temperature difference Td, and sets two setting values respectively corresponding to a first sampling number PN1 and a second sampling number PN2. The first sampling number PN1 is less than the second sampling number PN2. 
     Carrying on with step S 130 , as described in step S 440 , when the difference d is greater than the temperature difference Td, a setting value corresponding to the first sampling number PN1 is selected. When the difference d is less than or equal to the temperature difference Td, a setting value corresponding to the second sampling number PN2 is selected. 
     The sampling number corresponding to the setting value selected in step S 440 , that is, the first sampling number PN1 or the second sampling number PN2, is used in step S 150  of  FIG. 2  to acquire the value set G1. 
     In the embodiments of  FIG. 4  and  FIG. 5 , the difference d is compared with two preset temperature differences (that is, the first temperature difference Td1 and the second temperature difference Td2), to generate comparison results of three stages, and then the setting values are selected based on the comparison results. 
     In the embodiment of  FIG. 6 , the difference d is compared with a preset temperature difference Td to generate comparison results of two stages, and then the setting values are selected based on the comparison results, which is not limited thereto. According to actual fan control requirements, in other embodiments, by means of the disclosure, a larger number of temperature differences and a larger number of setting values are set to generate comparison results of more stages to control the rotational speed of a fan, so as to achieve more accurate control of the rotational speed of the fan. 
     Secondly, in the embodiments of  FIG. 4  to  FIG. 6 , the first sampling number PN 1 , the second sampling number PN 2 , and the third sampling number PN 3  that are preset are provided for selection, which is not limited thereto. 
     In other embodiments, an adjustment amount of the sampling number is also generated based on the difference d to increase or decrease the sampling number for previously controlling the rotation of the fan  30 , so as to achieve an effect of controlling the rotation of the fan by dynamically adjusting the sampling number. 
       FIG. 7  is a flowchart showing a fifth embodiment of the fan control method according to the disclosure. A main difference between this embodiment and the embodiment of  FIG. 2  lies in the step (that is, step S 120  and S 130  of  FIG. 2 ) of calculating the difference d. 
     In the embodiment of  FIG. 2 , a reference value set G0 is acquired from the temperature values based on a preset number i, a reference average value A0 of the reference value set G0 is calculated, and the difference d between the current temperature value (that is, the temperature value Sn) and the reference average value A0 is calculated. 
     By comparison, as described in step S 520 , in this embodiment, a difference d′ between the current temperature value (that is, the temperature value Sn) and a latest previous temperature value (that is, the temperature value Sn-1) is directly calculated, and then a sampling number corresponding to a setting value is selected based on the difference d′. 
     By means of the fan control method and the fan control system of the disclosure, the sampling number is dynamically adjusted based on the sampling temperature to adapt to different load change scenarios, which not only conforms to heat dissipation requirements, but also improves the auditory perception of users. In addition, the fan control method and fan control system of the disclosure also change a reaction speed of the fan to a temperature value change in response to changes in loads, so that the fan control is adapted to different system application conditions. 
     The above is merely exemplary embodiments of the disclosure, and does not constitute any limitation on the disclosure. Any form of equivalent replacements or modifications to the technical means and technical content disclosed in the disclosure made by a person skilled in the art without departing from the scope of the technical means of the disclosure still fall within the content of the technical means of the disclosure and the protection scope of the disclosure.