Patent Publication Number: US-2013241583-A1

Title: Device for testing short circuit protection function of power supply

Description:
BACKGROUND 
     1. Technical Field 
     The disclosure generally relates to testing devices, and particularly to a device for testing a short circuit protection function of a power supply. 
     2. Description of Related Art 
     During manufacture, a short circuit protection function of a power supply commonly needs to be tested. In a short circuit protection function of the power supply testing method, the power supply is electrically connected to a load via a testing fixture which converts a voltage output from the power supply into a preset voltage for the load. A mechanical switch is electrically connected between the load and the testing fixture. Thus, the power supply can be short-circuited by manually turning on the mechanical switch to test the short circuit protection function. 
     However, in above method, the mechanical switch may generate noise while being turned on. The noise may interfere to a test result such as waveform of the voltage output form the power supply shown by an oscilloscope and negatively influence the test result. 
     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 disclosure. 
         FIG. 1  is a block diagram of a device for testing short circuit protection function of a power supply, according to an exemplary embodiment of the disclosure. 
         FIG. 2  is a partial circuit diagram of the device in  FIG. 1 , according to an exemplary embodiment of the disclosure. 
     
    
    
     DETAILED DESCRIPTION 
       FIG. 1  is a block diagram of a device  100  for testing short circuit protection function of a power supply  200 , according to an exemplary embodiment of the disclosure. The device  100  includes a testing fixture  10 , a load  30 , an oscilloscope  50 , a short circuit control module  70 , and a controller  90 . 
     In one embodiment, the power supply  200  includes a plurality of groups of power supply units  201 . Each power supply unit  201  includes a group of a positive power supply terminal and a negative power supply terminal. The positive power supply terminal of each power supply unit  20  is electrically connected to the testing fixture  10 . The negative power supply terminal of each power supply unit  20  is grounded. In this embodiment, the testing device  100  can test the short circuit protection functions of the power supply units  201  simultaneously. 
     The testing fixture  10  is electrically connected between the power supply  200  and the load  30 . The testing fixture  10  converts a voltage output from each power supply unit  201  into a preset voltage and outputs the converted voltage to the load  30 . The testing fixture  10  also can connect the power supply  200  to other testing apparatuses. In this embodiment, the testing fixture  10  includes a plurality of input terminal groups and a plurality of output terminal groups corresponding to the input terminal groups. 
     Each input terminal group includes a positive input terminal and a negative input terminal Each output terminal group includes a positive output terminal and a negative output terminal The input terminal groups correspond to the power supply units  201 . Each positive input terminal is electrically connected to one of the corresponding power supply unit  201 . Each negative input terminal is grounded. Each positive output terminal is electrically connected to the load  30 . Each negative output terminal is grounded. When one group of the positive output terminal and the negative output terminal is short-circuited, the corresponding power supply unit  201  is short-circuited and the short circuit protection function thereof can be tested. 
     The load  30  is configured for providing different loads to the power supply  200 . 
     The oscilloscope  50  is electrically connected to the positive power supply terminal of each power supply units  201  and configured for displaying waveforms of output voltages of each power supply unit  201 . When a particular power supply unit  201  is short-circuited, the short circuit protection function of the power supply unit  201  can be tested by adjusting whether the output voltage of the power supply unit  201  is decreased to about zero from the oscilloscope  50 . 
     The oscilloscope  50  may include a plurality of output channels corresponding to one of the power supply units  201 . Each output channel displays the waveform of the output voltage from one of the power supply unit  201 . 
     The short circuit control module  70  includes a plurality of driving circuits  71  and a plurality of short circuits  73  corresponding to the driving circuits  71 . Each driving circuit  71  is electrically connected to one of the corresponding short circuit  73  in series between one of the positive output terminals of the testing fixture  10  and the controller  90 . Each driving circuit  71  drives the corresponding short circuit  73  to short-circuit the corresponding power supply unit  201  by controlling of the controller  90 . 
     Referring to  FIG. 2 , in one exemplary embodiment, each driving circuit  71  includes two voltage dividing resistors R connected in series. Each of the resistors R is electrically connected between the controller  90  and ground. Each short circuit  73  is a switch such as a transistor or a relay. In this embodiment, each short circuit  73  is a metal-oxide-semiconductor field-effect transistor (MOSFET) as one example. A gate G of each short circuit  73  is electrically connected between the two resistors R. A drain D of each short circuit is  73  electrically connected to the positive terminal. A source S of each short circuit  73  is grounded. 
     The controller  90  controls one or more of the power supply units  201  to be short-circuited by the short circuit control module  70 . In one embodiment, the controller  90  sends a control signal such as a high level signal (i.e. logic 1) to the driving circuit  71 , the corresponding connected short circuit  73  is turned on, and the corresponding power supply unit  201  is short-circuited. Meanwhile, the controller  90  controls the oscilloscope  50  to display the waveform of the output voltage of the short-circuited power supply unit  201 . The short circuit protection function of the power supply unit  201  can be tested from the waveform. The controller  90  may be a computer or a single chip. 
     To test the short circuit protection functions of the power supply units  201 , the positive power supply terminal of each power supply units  201  is electrically connected to one of the positive input terminals of the testing fixture  10  and the oscilloscope  50 . The negative power supply terminal of each power supply units  201  is grounded. If some of the power supply units  201  need to be tested, the controller  90  sends the high level voltage to one or more of the driving circuits  71  corresponding to the power supply units  201 . The driving circuit  71  drives the corresponding short circuit  73  to turn on so that the power supply units  201  is short-circuited by the short circuit  73 . The short circuit protection function of some of the power supply units  201  can be test from the waveform shown by the oscilloscope  50  directly. 
     The device  100  controls the short circuit control module  70  to automatically short-circuit the power supply units  201  by the controller  90  so that the device  100  can have a higher degree of testing accuracy and testing efficiency than a mechanical testing method. 
     It is believed that the exemplary embodiments and their advantages will be understood from the foregoing description, and it will be apparent that various changes may be made thereto without departing from the spirit and scope of the disclosure or sacrificing all of its material advantages, the examples hereinbefore described merely being preferred or exemplary embodiments of the disclosure.