Patent Publication Number: US-9405352-B2

Title: Battery module, computer system having the same, and control method of the computer system

Description:
PRIORITY 
     This application is a continuation of prior application Ser. No. 12/177,200, filed on Jul. 22, 2008, which claimed the benefit under 35 U.S.C §119 (a) of a Korean patent application filed on Jul. 30, 2007 in the Korean Intellectual Property Office and assigned Serial No. 10-2007-0076336, the entire disclosure of which is hereby incorporated by reference. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     Aspects of the present invention relate to a battery module, a computer system having the same, and a control method of the computer system, and more particularly, to a battery module capable of performing a throttling function, a computer system having the same, and a control method of the computer system. 
     2. Description of the Related Art 
     Among computer systems, a notebook computer, a personal digital assistant, etc., are being widely used because they are portable and usable while being moved. Such an electronic device may either use an external power source supplied through an AC/DC adapter or a secondary battery charged by the adapter. 
     In a technical field related to the battery of the portable computer, there is much research dedicated to producing an extended battery life (EBL). For example, a narrow voltage direct current (NVDC) has been proposed to extend the life of the battery. 
     Meanwhile, a maximum consumable power discharged from the battery may vary according to the number and characteristics of battery cells provided therein. If power discharged from the battery is more than the maximum consumable power, an internal temperature of the battery rapidly increases. For example, when operations that require substantial power are performed, the temperature of the battery increases quickly. Such demanding operations include reproducing a recordable medium, operating a computer game, and the like. The maximum consumable power refers to the maximum value within a range in which the battery can stably supply current to a load. 
     As the temperature of the battery increases and reaches a critical point, a logical fuse, a positive thermal coefficient (PTC) element, etc., which are susceptive to temperatures are cut off one after another, so that a system using the battery suddenly stops. In such case, the system may fail and unsaved data may be lost. 
     SUMMARY OF THE INVENTION 
     Accordingly, it is an aspect of the present invention to provide a battery module capable of stably supplying power, a computer system having the same, and a control method of the computer system. 
     Another aspect of the present invention is to provide a computer system and a control method thereof, which are capable of preventing a system error and a data loss due to sudden power-off. 
     Aspects of the present invention provide a computer system including a device which operates according to a predetermined clock frequency; a battery unit, which comprises a plurality of battery cells, to supply power to the device; a temperature sensor to sense a temperature of the battery cells; and a controller to control the clock frequency of the device according to at least the sensed temperature, wherein the controller decreases the clock frequency if the sensed temperature is beyond a first preset critical point. 
     According to an aspect of the invention, the computer system may include a current sensor which senses current output from the battery unit, wherein the controller decreases the clock frequency if the sensed current is beyond a second preset critical point. 
     According to an aspect of the invention, the controller may include a first comparator which compares a voltage level corresponding to the sensed temperature with a voltage level corresponding to the first critical point; a second comparator which may compare a voltage level corresponding to the sensed current with a voltage level corresponding to the second critical point; and a logical sum operator which may include a first input terminal connected to an output terminal of the first comparator and a second input terminal connected to an output terminal of the second comparator, and outputs a clock control signal to the device. 
     According to an aspect of the invention, the same reference voltage level may be input to the first comparator and the second comparator. 
     According to an aspect of the invention, the controller may further include a scaling factor unit that scales at least one of the voltage level corresponding to the sensed temperature and the voltage level corresponding to the sensed current as a dimension of the reference voltage level. 
     According to an aspect of the invention, the device may include a thermal throttling circuit to control the clock frequency according to temperature, and the thermal throttling circuit is controlled according to a clock control signal applied to the thermal throttling circuit by the controller. 
     According to an aspect of the invention, the thermal throttling circuit may include a divider to divide the clock frequency. 
     Aspects of the present invention provide a computer system including a device which operates depending on a predetermined clock frequency; a battery unit which supplies power to the device; and a controller which controls the clock frequency if at least one of current output and temperature of the battery unit is beyond a preset critical range. 
     According to an aspect of the invention, the device may include a thermal throttling circuit to adjust the clock frequency according to temperature, and the controller enables the thermal throttling circuit. 
     Aspects of the present invention provide a battery module used in a computer system having a system part that operates depending on a predetermined clock frequency, the battery module includes a battery unit which includes a plurality of battery cells and supplies power to the system part; a temperature sensor which senses temperature of the battery cells; a current sensor which senses current output from the battery unit; a scaling factor unit which scales at least one of a voltage level corresponding to the sensed temperature and a voltage level corresponding to the sensed current as a dimension of a reference voltage level; a first comparator which compares a voltage level corresponding to the sensed temperature with the reference voltage level; a second comparator which compares a voltage level corresponding to the sensed current with the reference voltage level; and a logical sum operator which includes a first input terminal connected to an output terminal of the first comparator and a second input terminal connected to an output terminal of the second comparator, and outputs a clock control signal to the system part. 
     Aspects of the present invention provide a power control method of a computer system that includes a battery unit and a device operating depending on a predetermined clock frequency, the power control method including sensing temperature of the battery unit; and decreasing the clock frequency if the sensed temperature is beyond a first preset critical point. 
     According to an aspect of the invention, the power control method may further include sensing current output from the battery unit; and decreasing the clock frequency if the sensed current is beyond a second preset critical point. 
     According to an aspect of the invention, the device may include a thermal throttling circuit to control the clock frequency according to temperature, and the decreasing the clock frequency includes enabling the thermal throttling circuit; and dividing the clock frequency. 
     Additional aspects and/or advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention. 
     Aspects of the present invention provide a power control method of a computer system that comprises a battery unit and a device operating according to a clock frequency, the power control method comprising: sensing a temperature of the battery unit; sensing a current output from the battery unit; and decreasing the clock frequency if the sensed temperature is beyond a first preset critical point or if the sensed current is beyond a second preset critical point. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The above and/or other aspects of the present invention will become apparent and more readily appreciated from the following description of the exemplary embodiments, taken in conjunction with the accompanying drawings, in which: 
         FIG. 1  is a control block diagram of a computer system according to a first exemplary embodiment of the present invention; 
         FIG. 2  is a control block diagram of a computer system according to a second exemplary embodiment of the present invention; 
         FIG. 3  is a control block diagram of a device according to the second exemplary embodiment of the present invention; 
         FIG. 4  illustrates a decrease in a clock frequency according to the second exemplary embodiment of the present invention; 
         FIGS. 5A through 5D  are graphs illustrate a throttling effect according to the second exemplary embodiment of the present invention; and 
         FIG. 6  is a control flowchart of a control method of the computer system according to the second exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Reference will now be made in detail to the present embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to the like elements throughout. The embodiments are described below in order to explain aspects of the present invention by referring to the figures. 
       FIG. 1  is a control block diagram of a computer system according to an exemplary embodiment of the present invention. As shown therein, a computer system includes a device  10 ; a battery unit  20  including battery cells  25 ; a temperature sensor  30 ; and a controller  40  to control the device  10 , the battery unit  20 , and the temperature sensor  30 . 
     The device  10  operates depending on a predetermined clock frequency and causes the computer system to perform various operations. In this embodiment, the device  10  may include a central processing unit (CPU), a graphic chip, or the like, which includes an independent controller and operate and process data. Here, the device  10  operates and processes data depending on a core clock or a similar clock. The speed of operating and processing data increases as the frequency of the core clock increases. Further, an interior temperature of the device  10  increases as the speed of operating and processing data increases. To control the interior temperature, the device  10  can independently control the clock frequency. In other words, the device  10  according to aspects of the present embodiment has a throttling function that changes the clock frequency to control the temperature and power. 
     The battery unit  20  includes the battery cells  25  and supplies the device with power. A rechargeable auxiliary power source, such as the battery unit  20 , is necessary to a portable computer, such as a notebook computer, a personal digital assistant (PDA), etc. The battery cells  25  are connected in series or parallel and output power at various voltage levels. The more battery cells  25  the battery unit  20  includes, the greater the maximum consumable power that is output. The maximum consumable power refers to the maximum value within a range in which the battery can stably supply current to a load. As the speed of operating and processing data in the device  10  increases, the power consumption increases and a power supply which supplies the device  10  with the power, particularly, the battery unit  20  used as the auxiliary power source, increases in temperature. Further, if the battery unit  20  discharges power at a level greater than the maximum consumable power, the interior temperature of the battery unit  20  increases so rapidly that internal elements of the computer system, such as a logical fuse, a positive thermal coefficient (PTC) element, etc., are cut off one after another. Accordingly, it is beneficial to make the battery unit  20  output the power stably. 
     The temperature sensor  30  senses the temperature of the battery unit  20 , i.e., the battery cells  25 , and outputs the sensed temperature to the controller  40 . The temperature sensor  30  may output to the controller  40  a voltage level corresponding to the sensed temperature. Alternatively, the temperature sensor  30  may convert analog information about the sensed temperature into digital data and output the digital data corresponding to the sensed temperature to the controller  40 . 
     If the temperature of the battery cells  25  is higher than a predetermined critical point, the controller  40  decreases the clock frequency of the device  10 . Here, the controller  40  may directly decrease the clock frequency of the device  10  or enable the throttling function of the device  10 . The critical point is set to be lower than a temperature managed in the battery unit  20 . For example, a smarter battery, which may be used as the battery unit  20 , stops supplying power in order to protect itself when the interior temperature thereof reaches a certain temperature (about 80° C.). In such case, the predetermined critical point may be set in a range from 45° C. to 60° C. When the sensed temperature is higher than the predetermined critical point, the controller  40  may decrease the clock frequency of the device  10  so as to stably supply the power and preliminarily protect the computer system. 
     As the clock frequency becomes lower, not only the speed of operating and processing the data decreases but also the power needed for operating and processing the data decreases. Consequently, the amount of current supplied from the battery cells  25  decreases, and the temperature of the battery cells  25  decreases. As the temperature of the battery cells  25  decreases, the computer system is prevented from being suddenly cut off. Further, data loss due to the sudden cut-off is prevented. 
       FIG. 2  is a control block diagram of a computer system according to an exemplary embodiment of the present invention. As shown therein, the computer system in this embodiment includes an adapter  110 , a battery  120 , a first switch  131 , a second switch  132 , a DC/DC converter  140 , a cell temperature sensor  200 , a current sensor  300 , and a controller  400  to control the foregoing and/or other elements. The controller  400  includes a first scaling factor unit  410 , a second scaling factor unit  420 , a first comparator  430 , a second comparator  440 , and an OR gate  450 , and operates similar to the controller in the above-described embodiment associated with  FIG. 1 . 
     The adapter  110  is used as a main power source to supply DC power converted from AC power to the device  10 . The AC power input through the adapter  110  is converted into the DC power by the DC/DC converter  140 , and the DC power is supplied to the system such as the device  10  or the like. Further, the adapter  110  supplies the battery  120  with power for charging the battery  120  via a predetermined path (not shown). 
     The battery  120  includes a plurality of battery cells  125  and supplies the device  10  with auxiliary power. If the amount of current output from the battery  120  increases, the temperature of the battery cells  125  increases. The temperature of the battery cells  125  may increase by a malfunction or the like in addition to or instead of to the temperature increase in proportion to the increased current amount. 
     The first switch  131  and the second switch  132  are provided as OR logic switches to supply the device  10  with the power from either of the adapter  110  or the battery  120 . If the device  10  is supplied with the power from the adapter  110 , the power from the battery  120  is cut off. However, if there is no power from the adapter  110 , the battery  120  supplies the power to the device  10 . As shown in  FIG. 2 , the first switch  131  and the second switch  132  are provided as a field effect transistor (FET); however, the first switch  131  and the second switch  132  are not limited thereto. Additionally, the computer system may include a switch controller (not shown) to sense whether the power is supplied from the adapter  110  and transmits a control signal A to each of the first switch  131  and second switch  132 . 
     In this embodiment, the computer system includes a cell temperature sensor  200  corresponding to the temperature sensor  30  of the above embodiment of  FIG. 1 . 
     The current sensor  300  senses the amount of current output from the battery  120 . The current sensor  300  according to this embodiment outputs a voltage level corresponding to the sensed current, but not limited thereto. Alternatively, the current sensor  300  may output a digital signal corresponding to the sensed current. 
     The first scaling factor unit  410  scales the voltage level corresponding to the temperature sensed by the cell temperature sensor  200  as a dimension of a reference voltage level Vref, and the second scaling factor unit  420  scales the voltage level corresponding to the current sensed by the current sensor  300  as a dimension of the reference voltage level Vref. The first scaling factor unit  410  and the second scaling factor unit  420  may be provided as resistors. The same reference voltage level Vref is input to the first comparator  430  and the second comparator  440  as a reference. Thus, the voltage level input to each comparator  430  and  440  is scaled as a dimension of the reference voltage level Vref. 
     In another embodiment, the cell temperature sensor  200  and the current sensor  300  may output information, such as temperature and current, instead of the voltage level. To this end, the first scaling factor unit  410  and second scaling factor unit  420  may include a lookup table or the like to convert the temperature and the current into the dimension of the reference voltage. Here, the lookup table includes information about the voltage level corresponding to the input temperature and the input current, and each of the first scaling factor unit  410  and second scaling factor unit  420  outputs a scaled value corresponding to the temperature and the current. 
     The first comparator  430  compares a voltage level corresponding to temperature input through a non-inversion terminal with the reference voltage level input through an inversion terminal and outputs a predetermined signal through an output terminal if the voltage level corresponding to the sensed temperature is higher than the reference voltage level Vref. The second comparator  440  compares a voltage level corresponding to current input through the non-inversion terminal with the reference voltage level input through the inversion terminal and outputs a predetermined signal through an output terminal if the voltage level corresponding to the sensed current is higher than the reference voltage level Vref. 
     The OR gate  450  is an element that implements a logical sum, of which a first input terminal connected to the output terminal of the first comparator  430  and a second input terminal connected to the output terminal of the second comparator  440 . The OR gate  450  outputs a control signal if it receives the signal from either of the first comparator  430  or second comparator  440 . The control signal output from the OR gate  450  is used as a clock control signal to enable the throttling function to lower the clock frequency of the device  10 , such as the CPU or the graphic chip. In other words, the controller  400  outputs the clock control signal to enable the throttling function of the CPU or the graphic chip if either of the sensed current or the sensed temperature is beyond the critical point. 
       FIG. 3  is a control block diagram of the device according to an exemplary embodiment of the present invention, which explains a throttling function of the device  10 . As shown therein, if it is sensed that the interior temperature of the device  10 , such as the CPU or the graphic chip, reaches a certain critical point, a throttling operation to decrease the clock frequency is performed. To this end, the device  10  includes a silicon temperature sensor  11 , an internal comparator  12 , an auto mode/on-demand mode selector  13 , and a thermal throttling circuit  14 . Here, the thermal throttling circuit  14  includes a thermal control circuit  15  and a throttling enabler  16 . 
     The internal comparator  12  compares the temperature input from the silicon temperature sensor  11  with an internal reference value Vref′, and activates the thermal control circuit  15  when the sensed temperature is higher than the reference value Vref′. 
     The auto mode/on-demand mode selector  13  operates depending on a basic input/output system (BIOS) to thereby switch operation of the thermal control circuit  15  between an auto mode and an on-demand mode. Here, the thermal control circuit  15  operates when the auto mode/on-demand mode selector  13  outputs an enable signal. The enable signal output from the auto mode/on-demand mode selector  13  is a precondition for operating the thermal throttling circuit  14 . 
     The thermal control circuit  15  outputs an enable signal to the throttling enabler  16  if the clock control signal is output from the OR gate  45  (refer to  FIG. 2 ), and controls the throttling enabler  16  to lower the clock frequency. Here, the throttling enabler  16  changes the clock frequency and may be realized as a time-sharing divider that divides the clock frequency. 
       FIG. 4  shows waveforms to explain a decrease in a clock frequency according to the exemplary embodiment of the present invention. In  FIG. 4 , (a) illustrates the core clock frequency of the CPU or the graphic chip, which typically ranges about from 1 GHz to 2 GHz; and (b) through (d) indicate that various divisions are applied to the core clock frequency. Specifically, (b), (c), and (d) indicate that divisions of ⅛, ½ and ⅞ are applied to the clock frequency having a certain period T, respectively. In the auto mode, the division of ½ is applied to the clock frequency (refer to (c)). (e) denotes the core clock frequency for two periods, which is divided like (c) and in which waveforms of (a) and (c) are synthesized. The clock frequency is enabled and output for a half of the certain period T, but disabled and not output for the other half. While the clock frequency is disabled, the CPU or the graphic chip temporarily becomes idle and thus power consumption decreases. Accordingly, the temperature of the battery  120  is decreased. 
       FIGS. 5A through 5D  are graphs showing a throttling effect according to an exemplary embodiment of the present invention.  FIG. 5A  shows a power consumption in the battery  120  and a temperature change of the battery cell  125  as time passes in the case that the throttling function is disabled. If a power of about 50 W, on average, 53.4 W is continuously consumed from the battery cells  125 , the temperature of the battery cells  125  increases as time progresses. 
       FIG. 5B  is a graph showing the power consumption and the temperature change in the battery  120  in the case that the throttling function is enabled when the battery cells  125  are maintained at a temperature of about 45° C. or more for approximately four minutes, and  FIG. 5C  is a graph showing the power consumption and the temperature change in the battery  120  in the case that the throttling function is enabled when the battery cells  125  are maintained at a temperature of about 50° C. or more for approximately four minutes. As shown in  FIGS. 5B and 5C , if the throttling function is enabled, a temperature increase rate of the battery cells  125  is lowered, and the power consumption is rapidly decreased. When the throttling function was enabled at the temperature of about 45° C., an average power consumption was about 44.86 W. When the throttling function was enabled at the temperature of about 50° C., an average power consumption was about 45.81 W. The power consumption based on the enabled throttling function is less than that based on the disabled throttling function, so that the battery  120  can stably supply power and increase in lifespan. 
     The throttling function is disabled if the battery cells  125  are maintained for a predetermined time at a temperature that is lower than the temperature causing the throttling function to be enabled. For example, in the case shown in  FIG. 5B , the clock frequency may increase if the battery cells  125  are maintained for about two minutes or more under the temperature of 40° C. and below; and in the case shown in  FIG. 5C , the clock frequency may increase if the battery cells  125  are maintained for about two minutes or more under the temperature of 45° C. and below. 
     With reference to  FIG. 5D , the temperatures of the battery cells  125  for each of the above-described throttling situations are compared. As can be seen in  FIG. 5D , when the throttling function is disabled, the temperature of the battery cells  125  continues to rise. When the throttling function is enabled at the temperatures of 45° C. and 50° C., it can be seen that the temperatures of the battery cells  125  increases less than when the throttling function is disabled. 
       FIG. 6  is a control flowchart that explains a control method of the computer system according to the second exemplary embodiment of the present invention. As shown in  FIG. 6 , the controller  400  operates as follows: First, the cell temperature sensor  200  senses the temperature of the battery cells  125  at operation S 10 , and the current sensor  300  senses the current output from the battery  120  at operation S 20 . 
     At operations S 30  and S 40 , the voltage level corresponding to the sensed temperature and the voltage level corresponding to the sensed current are scaled as the dimension of the reference voltage level by the first scaling factor unit  410  and the second scaling factor unit  420 , respectively. At operations S 50  and S 60 , the first comparator  430  and the second comparator  440  determine whether the scaled voltage level corresponding to the temperature and the scaled voltage level corresponding to the current are beyond the reference voltage level, respectively. 
     In a determination result, if either of the voltage level corresponding to the temperature or the voltage level corresponding to the current is beyond the reference voltage level, the controller  400  enables the thermal throttling circuit  14  provided in the device  10  at operation S 70 . 
     The thermal control circuit  15  of the thermal throttling circuit  14  receives the clock control signal corresponding to the enable signal, and controls the throttling enabler  16  to divide the clock frequency at operation S 80 . 
     The temperature control circuit  15  may control the throttling enabler  16  according to a logical sum between an activation signal from the internal comparator  12  and the clock control signal from the controller  400 , but the temperature control circuit  15  is not limited thereto as such control is not necessary. 
     Alternatively, the reference voltage levels Vref input to the first comparator  430  and the second comparator  440  may be different from each other. As such, the reference voltage level Vref to be input to the first comparator  430  is set as a level corresponding to a critical temperature at which consumable power output from the battery  120  is not higher than the maximum consumable power. Likewise, the reference voltage level Vref to be input to the second comparator  440  is set as a level corresponding to a critical current at which consumable power output from the battery  120  is not higher than the maximum consumable power. Accordingly, at least one of the first scaling factor unit  410  and the second scaling factor unit  420  may be not needed. 
     Further, the adapter  110 , the switches  131  and  132 , and the DC/DC converter  140  may be separated from the computer system and may be provided in a battery module. In such case, the clock control signal output from the controller  400  may be transmitted to the device  10  via a general system bus. Alternatively, other elements except the battery  120  may be provided in the computer system. 
     Although a few embodiments of the present invention have been shown and described, it would be appreciated by those skilled in the art that changes may be made in this embodiment without departing from the principles and spirit of the invention, the scope of which is defined in the claims and their equivalents.