Patent Publication Number: US-2013238275-A1

Title: Thermal protection critical temperature setting device, system and method

Description:
BACKGROUND 
     1. Technical Field 
     Present disclosure is related to devices for setting a thermal protection critical temperature, and is further related to a device, a system, and a method for the thermal protection critical temperature of a switching power supply. 
     2. Description of Related Art 
     To increase a reliability of an element, a working temperature of the element is designed to be lower than a reduced rated temperature. The reduced rated temperature of the element is a reduction of a rated temperature of the element. For example, an temperature of the element is normally limited to be smaller than 80% of the rated temperature when the element is working, and the reduced rated temperature is the 80% of the rated temperature. 
     In thermal protection methods of a switching power supply, a power supply of a main board for example, the temperatures of a transistor, an inductor, and other electronic elements are less than the reduced rated temperatures of the elements. A temperature-sensing element is set around the transistor to measure the temperature of the transistor. When the temperature of the transistor reaches the reduced rated temperature, a power controller of the switching power supply starts to execute the thermal protection methods for the switching power supply. The thermal protections methods are controlling a central processing unit to reduce a working frequency and controlling a fan to increase a rotational speed of the fan. And the temperature of the temperature-sensing element is the thermal protection critical temperature of the switching power supply. 
     But, each of the power supply elements in the switching power supply has a different reduced rated temperature. When the power supply element which is in an outer area exceeds the reduced rated temperature of the power supply element, the temperature-sensing element may not reach the reduced rated temperature of the temperature-sensing element, and the power controller thus does not execute the thermal protection to the switching power supply. The temperature of the temperature-sensing element may exceeds the reduced rated temperature, and the temperature-sensing element may work in a hot environment and suffer a decrease in service life, and even more so, the service life of the switching power supply is decreased. 
     Therefore, there is room for improvement within the art. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily drawn to scale, the emphasis instead being placed upon clearly illustrating the principles of the present embodiments. 
         FIG. 1  is a functional module diagram of one embodiment of the present disclosure of a switching power supply of a thermal protection critical temperature setting device. 
         FIG. 2  is a functional module diagram of one embodiment of the present disclosure of the thermal protection critical temperature setting device. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  and  FIG. 2  are embodiments of present disclosure of thermal protection critical temperature setting system. The system includes a switching power supply  20  and a thermal protection critical temperature setting device  10  for setting a thermal protection critical temperature of the switching power supply  20 . 
     In the embodiment, the switching power supply  20  is used in a computer (not shown) and supplies electrical power to elements of the computer. The switching power supply  20  includes a plurality of power supply elements  22  set on a circuit board, a power controller  24 , and a temperature-sensing element  26  electronically connected to the power controller  24 . The power supply elements  22  comprise a metal-oxide-semiconductor field-effect transistor (MOSFET)  22   a,  an inductor  22   b,  and a capacitor  22   c.  In the embodiment, the temperature-sensing element  26  is a thermistor. Each of the power supply elements  22  has a reduced rated temperature, for example, the reduced rated temperature of the inductor  22   b  is seventy-five degrees Celsius, and the reduced rated temperature of the MOSFET  22   a  is one-hundred-twenty-five degrees Celsius. The temperature-sensing element  26  is set close to the MOSFET  22   a  and the inductor  22   b.  Temperature of the temperature-sensing element  26  increases when the temperature of the power supply elements  22  increases. When the temperature of the temperature-sensing element  26  reaches the thermal protection critical temperature of the switching power supply  20 , the power controller  24  executes thermal protection methods for the switching power supply  20 . For example, the power controller  24  controls a central processing unit to reduce processing speed of the processor, or controls a fan of the computer to increase a rotational speed of the fan. 
     The device  10  includes a high-temperature unit  11 , a temperature measurement element  13 , and a processor  15 . The high-temperature unit  11  increases an ambient temperature of the switching power supply  20  until the ambient temperature of the switching power supply  20  about equals to temperature of the switching power supply  20  in a working state. In the embodiment, the ambient temperature of the switching power supply  20  is thirty-five degrees Celsius. The switching power supply  20  in the working state is subjected to a load such as the central processing unit, for example. 
     The temperature measurement element  13  measures temperatures of each of the power supply elements  22  and the temperature-sensing element  26 , and transmits the temperatures to the processor  15 . In the embodiment, the temperature measurement element  13  is a thermocouple wire electronically connected to the processor  15 . 
     Data as to the reduced rated temperature of each of the power supply elements  22  is saved by the processor  15 . The processor  15  compares the temperature of each of the power supply elements  22  with the reduced rated temperature of each of the power supply elements  22 . When at least one temperature of the power supply elements  22  is greater than the reduced rated temperature of the of the power supply element  22 , the processor  15  calculates the difference in temperature between the at least one temperature and the reduced rated temperatures for establishing the greatest difference. The processor  15  subtracts the greatest difference from the temperature of the temperature-sensing element  26 , and a result of the above subtraction is a thermal protection critical temperature of the switching power supply  20 . 
     A high temperature test is controlling the high-temperature unit  11  to raise the ambient temperature of the switching power supply  20  until the ambient temperature equals temperature of the switching power supply  20  in a working state. For example, when the switching power supply  20  is put into the high-temperature unit  11  to undergo the high temperature test, the temperature of the capacitor  22   c  measured by the temperature measurement element  13  is eighty-five degrees Celsius, but the temperature of the temperature-sensing element  26  is one-hundred degrees Celsius. The processor  15  calculates the difference in temperature between the temperature, which is eighty-five degrees Celsius, of the capacitor and the reduced rated temperature, which is seventy-five degrees Celsius, which is ten degrees Celsius. Then the processor  15  subtracts the difference in temperature, which is ten degrees Celsius, from the temperature of the temperature-sensing element  26 , which is one-hundred degrees Celsius, and the result, ninety degrees Celsius, of the above subtraction is the thermal protection critical temperature of the switching power supply  20 . When the temperature of the capacitor  22   c  reaches the reduced rated temperature of the capacitor  22   c,  the temperature of the temperature-sensing element  26  matches the thermal protection critical temperature. And the power controller  24  executes the thermal protection methods for the switching power supply  20  to prevent the capacitor  22   c  from working at a temperature which is too high. 
     The device  10  further includes a display  17  electronically connected to the processor  15 . When the processor  15  calculates the thermal protection critical temperature of the switching power supply  20 , the thermal protection critical temperature is displayed on the display  17 . 
     A method for setting thermal protection critical temperature by using the device  10  for setting the thermal protection critical temperature includes following steps: 
     The device  10  and the switching power supply  20  are provided. The device  10  includes the high-temperature unit  11 , the temperature measurement element  13 , and the processor  15 . The switching power supply  20  includes the plurality of power supply elements  22 , the power controller  24 , and the temperature-sensing element  26  electronically connected to the power controller  24 . 
     The switching power supply  20  which provides loads is put into the high-temperature unit  11 . The high-temperature unit  11  provides a high ambient temperature which is temperature of the switching power supply  20  in actual usage. 
     Each temperature of the power supply elements  22  and the temperature of the temperature-sensing element  26  are measured, and each temperature of the power supply elements  22  and the temperature of the temperature-sensing element  26  are transmitted to the processor  15 . 
     Each temperature of the power supply elements  22  is compared with the reduced rated temperatures of the power supply elements  22 . 
     When at least one temperature of the power supply elements  22  is greater than the reduced rated temperature of the power supply elements  22 , the processor  15  calculates the difference in temperature between the temperature of the at least one power supply element  22  and the reduced rated temperature of the power supply element  22 . The processor  15  subtracts the largest difference in temperature from the temperature of the temperature-sensing element  26 , and the result of above subtraction is the thermal protection critical temperature of the switching power supply  20 . 
     It is to be further understood that even though numerous characteristics and advantages of the present embodiments have been set forth in the foregoing description, together with details of structures and functions of various embodiments, the disclosure is illustrative only, and changes may be made in detail, especially in the matter of arrangement of parts within the principles of the present disclosure to the full extent indicated by the broad general meaning of the terms in which the appended claims are expressed.