Abstract:
A power supply operable from a plurality of alternating current inputs had having protection from abnormal operation. The power supply includes a switchable rectifier and a voltage to voltage converter. Protection circuits switch off at least one of the rectifier and the converter if the rectified voltage exceeds a predetermined voltage value and/or a current through the converter exceeds a predetermined current value. The protection circuits include latch circuits to prevent cyclic operation.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of Korean Patent Application No. 2005-79524, filed Aug. 29, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
   BACKGROUND OF THE INVENTION 
   1. Field of the Invention 
   Aspects of the present invention relate to a power supplying apparatus and a power supplying method, and more particularly, to a power supplying apparatus and a power supplying method which protect a circuit safely against over-voltage and over-current. 
   2. Description of the Related Art 
   A power supplying apparatus supplies proper power necessary to operate a circuit apparatus such as a computer system. Such circuit apparatus often needs direct current power as power, and consequently the power supplying apparatus rectifies input alternating current power and outputs direct current power. 
   Where the power supplying apparatus uses commercial alternating current power as an input, the input voltage may be a voltage such as 110V or 220V. Therefore, in order to accommodate both 110V and 220V input voltages, the power supplying apparatus uses the input 220V voltage “as is” and the input 110V input is doubled. Such a conventional power supplying apparatus is illustrated in  FIG. 1 . 
   The power supplying apparatus shown in  FIG. 1  includes a rectifying part  12 , a voltage selector  13 , and a smoothing part  15 . The rectifying part  12  includes diodes  12   a ,  12   b ,  12   c  and  12   d  and rectifies input alternating current power  11 . The smoothing part  15  includes capacitors  15   a  and  15   b  that correspond to the input power  11  of 110V and 220V, for example, and charges energy of the current rectified by the rectifying part  12  into each capacitor  15   a  and  15   b.    
   The voltage selector  13  is disposed in a predetermined current path between the rectifying part  12  and the smoothing part  15 , and serves as a switch to pass or interrupt the current. As shown in  FIG. 1 , if the voltage selector  13  is open, a voltage proportional to a magnitude of the input power is charged in the series combination of the capacitors  15   a  and  15   b . However, if the voltage selector  13  is closed, a voltage proportional to a magnitude of the input power voltage is charged in each of two capacitors  15   a  and  15   b . In this case, a voltage corresponding to double the magnitude of the input voltage is charged into the series combination of capacitors  15   a  and  15   b . That is, where the input voltage is 110V, the power supplying apparatus outputs a direct current voltage proportional to double the input voltage. 
   However, although the input voltage is 220V, the voltage selector  13  may be closed due to a user&#39;s mistake or erroneous operation of the apparatus. In this case, the capacitors  15   a  and  15   b  may be damaged due to a voltage 1.4 times 220V being applied to each of the capacitors  15   a  and  15   b.    
   The power supplying apparatus  1  universally uses a switch-mode power supply (SMPS) which is advantageous in terms of efficiency. The switch-mode power supplying apparatus  1  further includes a MOSFET  17   a , a transformer  18 , and diodes  19   a  and  19   b . The power supplying apparatus  1  converts a magnitude of the voltage applied to the smoothing part  15  through the transformer  18  to output a voltage Vo with turning on and off the MOSFET  17   a  using pulse width modulation (PWM). 
   According to the switch-mode power supplying apparatus  1 , if the voltage selector  13  is closed due to user&#39;s mistake and an input voltage of 220V is supplied, an over-current may result in the MOSFET  17   a , potentially resulting in an explosion. Further, even if the input voltage is applied consistent with the position of the voltage selector  13 , if a problem related to feedback loop occurs upon operating the PWM or gate on time in the MOSFET  17   a  is raised due to degradation of a PWM controller IC, the MOSFET  17   a  may be also damaged. 
   SUMMARY OF THE INVENTION 
   Accordingly, an aspect of the present invention is to provide a power supplying apparatus and a power supplying method with superior stability against over-voltage and over-current. 
   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. 
   The foregoing and/or other aspects of the present invention may be achieved by providing a power supplying apparatus comprising: a rectifying part rectifying an input alternating current to output a direct current; a smoothing part connectable with the rectifying part in a plurality of current paths and smoothing a voltage of the direct current input from the rectifying part through each of the current paths; a voltage selecting part selecting a magnitude of the smoothed voltage by controlling at least one of the plurality of current paths; and a smoothing protection part estimating the magnitude of the smoothed voltage and suspending the direct current output from the rectifying part if the estimated magnitude of the voltage is determined to be more than a predetermined voltage value. 
   According to an aspect of the present invention, the smoothing protection part comprises a first operation maintaining part which maintains the suspending of the output direct current. 
   According to an aspect of the present invention, the power supplying apparatus further comprises: a transforming part converting the magnitude of the smoothed voltage to output another voltage; a switching part determining the magnitude of the another voltage by controlling a flow of a current input to the transforming part; and a switching protection part estimating a magnitude of the current flowing in the switching part and suspending an operation of the switching part if the estimated magnitude of the current is more than a predetermined value. 
   According to an aspect of the present invention, the switching protection part comprises a second operation maintaining part which maintains the suspending of the switching part. 
   According to an aspect of the present invention, the switching protection part estimates the magnitude of the current flowing in the switching part and suspends the direct current output from the rectifying part if the estimated magnitude of the current flowing in the switching part is more than the predetermined current value. 
   According to an aspect of the present invention, the smoothing protection part estimates the magnitude of the smoothed voltage and suspends the operation of the switching part if the estimated magnitude of the smoothed voltage is more than the predetermined voltage value. 
   The foregoing and/or another aspects of the present invention may be achieved by providing a power supplying apparatus, comprising: a rectifying part rectifying an input alternating current to output a direct current; a smoothing part connectable with the rectifying part in a plurality of current paths and smoothing a voltage of the direct current input from the rectifying part; a voltage selecting part selecting a magnitude of the smoothed voltage by controlling at least one of the plurality of current paths; a transforming part converting the magnitude of the smoothed voltage to output another voltage; a switching part determining a magnitude of the another voltage by controlling a flow of the current input to the transforming part; and a switching protection part estimating a magnitude of the current flowing in the switching part and suspending an operation of the switching part if the estimated magnitude of the current flowing in the switching part is determined to be more than a predetermined current value. 
   According to an aspect of the present invention, the switching protection part comprises an operation maintaining part which maintains the suspending of the switching part. 
   The foregoing and/or another aspects of the present invention may be achieved by providing a method of operating a power supplying apparatus comprising a rectifying part rectifying an input alternating current to output a direct current; a smoothing part connectable with the rectifying part in a plurality of current paths and smoothing a voltage of the direct current input from the rectifying part; a voltage selecting part selecting a magnitude of the smoothed voltage by controlling at least one of the plurality of current paths, the method comprising: estimating the magnitude of the smoothed voltage; and suspending the output of direct current from the rectifying part if the magnitude of the estimated voltage is more than a predetermined voltage value. 
   According to an aspect of the present invention, the suspending of the output of the direct current comprises maintaining the suspending the direct current output. 
   According to an aspect of the present invention, the power supplying apparatus further comprises a transforming part converting the magnitude of the smoothed voltage to output another voltage; a switching part determining the magnitude of the another voltage by controlling a flow of the current input to the transforming part, the power supplying method further comprising: estimating a magnitude of the current flowing in the switching part; and suspending the operation of the switching part if the magnitude of the estimated current is more than a predetermined current value. 
   According to an aspect of the present invention, the suspending of the operation of the switching part comprises maintaining the suspending of the switching part. 
   According to an aspect of the present invention, the power supplying method further comprises suspending the direct current output from the rectifying part if the magnitude of the current flowing in the switching part is more than the predetermined current value. 
   According to an aspect of the present invention, the power supplying method further comprises suspending the operation of the switching part if the magnitude of the smoothed voltage is more than the predetermined voltage value. 
   The foregoing and/or another aspects of the present invention may be achieved by providing a method of operating a power supplying apparatus including a rectifying part rectifying an input alternating current to output a direct current; a smoothing part connectable with the rectifying part in a plurality of current paths for smoothing a voltage of the direct current input from the rectifying part; a voltage selecting part selecting a magnitude of the smoothed voltage by controlling at least one of the plurality of current paths; a transforming part converting the magnitude of the smoothed voltage to output another voltage; and a switching part determining the magnitude of the another voltage by controlling a flow of the current input to the transforming part, the method comprising: estimating a magnitude of the current flowing in the switching part; and suspending the operation of the switching part if the magnitude of the estimated current is more than a predetermined value. 
   According to an aspect of the present invention, the suspending of the operation of the switching part comprises maintaining the suspending the switching part. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     These and/or other aspects and advantages of the invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which: 
       FIG. 1  is a schematic diagram showing a structure of a conventional power supplying apparatus using a method of doubling an input voltage. 
       FIG. 2  is a block diagram showing a structure of a power supplying apparatus according to an embodiment of the present invention. 
       FIG. 3  is a circuit diagram showing a circuit implementing the power supplying apparatus shown in  FIG. 2 . 
       FIG. 4  is a flow chart showing an operation of the power supplying apparatus of shown in  FIGS. 2 and 3 . 
   

   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 the present invention by referring to the figures. 
     FIG. 2  is a block diagram showing a structure of a power supplying apparatus  100  according to an embodiment of the present invention. The power supplying apparatus  100  supplies power to an electronic device, such as for example, a computer system. The power supplying apparatus  100  includes a rectifying part  120 , a voltage selecting part  130 , a smoothing part  150 , a smoothing protection part  151 , a switching part  170  and a transforming part  180 . An alternating current is input to the rectifying part  120  where the alternating current is rectified and output as a direct current. The smoothing part  150  is connected with the rectifying part  120  in a plurality of current paths for smoothing a voltage of the direct current input from the rectifying part  120 . The voltage selecting part  130  selects a magnitude of the voltage smoothed by the smoothing part  150  by controlling the plurality of current paths between the rectifying part  120  and the smoothing part  150 . The transforming part  180  converts the magnitude of the voltage smoothed by the smoothing part  150  and outputs the converted voltage. The switching part  170  determines a magnitude of the converted voltage by controlling a flow of a current input to the transforming part  180 . The smoothing protection part  151  may estimate a magnitude of the voltage smoothed by the smoothing part  150  and suspend the output of direct current from the rectifying part  120  if the estimated magnitude of the voltage is determined to be more than a predetermined voltage value. The power supply apparatus  100  may further comprise a switching protection part  171  estimating a magnitude of the current input to the transforming part  180  and suspending the output of the converted voltage if the current input to the transforming part is determined to be more than a predetermined current value. 
     FIG. 3  is a circuit diagram showing an example circuit implementing the power supplying apparatus  100 . The rectifying part  120  includes SCRs  120   a  and  120   b  and diodes  120   c  and  120   d  and rectifies input alternating power  110  to output direct current. The smoothing part  150  includes capacitors  150   a  and  150   b  and charges energy of the current rectified by the rectifying part  120  into each of the capacitors  150   a  or  150   b.    
   The voltage selecting part  130  is disposed in a predetermined current path between the rectifying part  120  and the smoothing part  150  and serves as a switch for passing or interrupting a current. As shown in  FIG. 3 , if the voltage selecting part  130  is open, a voltage proportional to a magnitude as the input power is charged into the series combination of the capacitors  150   a  and  150   b . If the voltage selecting part  130  is closed, the voltage proportional to the magnitude as the input power is charged into each of the capacitors  150   a  and  150   b . With the voltage selecting part closed, a voltage corresponding to double the input voltage is charged into the series combination of the capacitors  150   a  and  150   b . That is, with the voltage selecting part  130  closed and an input voltage of 110V, the voltage across the capacitors  150   a  and  150   b  is about the same as the voltage with an input voltage of 220V with the voltage selecting part open. 
   The power supplying apparatus  100  operates in a switch mode manner and further includes a MOSFET  170   a , a transforming part  180  and diodes  190   a  and  190   b . The MOSFET  170   a  is an example of the switching part  170  shown in  FIG. 2 . The power supplying apparatus  100  converts the magnitude of the voltage applied by the smoothing part  150  to the transforming part  180  to an output voltage Vo with turning on or off the MOSFET  170   a  using a switching technique, such as for example, pulse width modulation. 
   The smoothing protection part  151  includes resistors  151   a  and  151   b  sensing a voltage across the capacitors  150   a  and  150   b , a resistor  151   e  and a zener diode  151   c  providing a reference voltage, a comparator  151   d  having respective inputs to which a voltage across the resistor  151   b  and the reference voltage provided by the zener diode  151   c  are applied, and a diode  151   f  for determining a current direction of an output in the comparator  151   d . The output of the comparator  151   d  is connected with respective trigger inputs of the SCRs  120   a  and  120   b  via the diode  151   f . The power supplying apparatus  100  further includes a Vcc supplying part  111   a , a diode  111   b  and a resistor  111   c  supplying a voltage Vcc for the smoothing protection part  151  and the switching protection part  171 . 
   The reference voltage of the zener diode  151   c  is set correspondingly with a normal voltage across the capacitors  150   a  and  150   b . The resistance values of the resistors  151   a  and  151   b  are set so that when the power supplying apparatus  100  operates normally, a voltage across the resistor  151   b  is lower than the reference voltage of the zener diode  151   c  and in this case the output of the comparator  151   d  is High, thereby causing SCRs  120   a  and  120   b  to operate as diodes, resulting in normal rectifying operation. 
   If the power supplying apparatus  100  operates abnormally, as in a case where the voltage selecting part  130  is closed and the input voltage of 220V, the voltage across the resistor  151   b  will be higher than the reference voltage of the zener diode  151   c  and in this case the output of the comparator  151   d  is Low, thereby causing the SCRs  120   a  and  120   b  to be turned off interrupting the current output by the rectifying part  120 . Consequently, over-voltage is prevented from being charged into the capacitors  150   a  and  150   b.    
   The smoothing protection part  151  further includes a latch-up circuit holding the output of the comparator  151  Low. The latch-up circuit includes a transistor  151   h  and a resistor  151   i . The latch-up circuit prevents the abnormal operation and the protection operation from being cyclic. Without the latch-up circuit the smoothing protection part  151  operates to interrupt the current flowing in the rectifying part  120 , the voltage charged into the capacitor  150   b  is lowered so that the smoothing protection part  151  terminates the protection operation, the voltage charged into the capacitor  150   b  rises, and the smoothing protection part  151  again carries out the protection operation. 
   The power supplying apparatus  100  may further include a switching protection part  171  estimating a magnitude of the current flowing in the switching part  170  and suspending operation of the switching part  170  if the estimated magnitude of the current is determined to be more than a predetermined value. The switching protection part  171  includes a resistor  170   b  detecting a current flowing in a drain and a source of the MOSFET  170   a , resistors  171   d  and  171   e  providing a reference voltage of the over-current protection circuit, a comparator  171   c  having respective inputs to which the over-current protection reference voltage across the resistor  171   e  and a voltage across the resistor  170   b  are input, and a diode  171   f  determining a flow of a gate voltage signal to the MOSFET  170   a . The power supplying apparatus  100  further includes a PWM controller (not shown) supplying the gate voltage signal to the MOSFET  170   a.    
   The resistance values of resistors  171   d  and  171   e  are set correspondingly with the resistance value of the resistor  170   b  and a reference current of the MOSFET  170   a . If the power supplying apparatus  100  operates normally, the voltage across the resistor  170   b  is set lower than the over-current protection reference voltage, and in this case the output of the comparator  171   c  is High and the gate voltage signal to the MOSFET  170   a  from the PWM controller (not shown) is applied to the gate of the MOSFET  170   a  and the switching part  170  operates normally. 
   If the voltage selecting part  130  is closed with the input voltage of 220V, or the power supplying apparatus  100  operates abnormally as in cases of occurrence of a problem related to feedback loop of PWM operation or degradation of a PWM controller IC, the voltage across the resistor  171   b  becomes higher than the over-current protection reference voltage, and in this case the output of the comparator  151   d  is Low, thereby causing the gate voltage signal from the PWM controller to be interrupted by the output of the comparator  171   c  via the diode  171   f . Therefore, the operation of the MOSFET  170   a  is suspended to interrupt the current flowing through the drain and the source of the MOSFET  170   a  so that the MOSFET  170   a  is protected. 
   The switching protection part  171  further includes a latch-up circuit holding the output of the comparator  171   c  Low. The latch-up circuit of the switching protection part  171  may include a transistor  171   a  and a resistor  171   b . The latch-up circuit of the switching protection part  171  prevents the abnormal operations and the protection operation from being cyclic, in a similar manner as the latch-up circuit of the smoothing protection part  151  prevents cyclic operation. 
   The output of the comparator  151   d  and the output of the comparator  171   c  are mutually connected. Consequently, where the output in any one of the comparator  151   d  and the comparator  171   c  is Low, the smoothing part  150  and switching part  170  are both protected. 
     FIG. 4  is a flow chart showing an operation of the power supplying apparatus  100 . Power is supplied to the power supplying apparatus  100  at operation S 110  and a voltage level across the capacitors  150   a  and  150   b  is detected at operation S 111 . A determination of whether the detected voltage level is more than a reference voltage is made at operation S 112 , and an output of the comparator  151   d  is set as Low at operation S 113 , if the detected voltage level is more than the reference voltage, thereby causing the SCRs  120   a  and  120   b  to be turned off at operation S 114 . Therefore, the over-voltage across the capacitors  150   a  and  150   b  is interrupted at operation S 115 . 
   If the detected voltage level across the capacitors  150   a  and  150   b  is not more than the reference voltage, a determination of whether a current flowing in the MOSFET  170   a  is more than a reference current is made at operation S 116 . If the current flowing through the MOSFET  170   a  is more than the reference current, an output of the comparator  171   c  is set as Low at operation S 117 , thereby causing a gate voltage signal of the MOSFET  170   a  to be interrupted at operation S 118 . Therefore, over-current is prevented from flowing in the MOSFET  170   a.    
   As described above, the present invention provides a power supplying apparatus and a power supplying method with superior stability against over-voltage and over-current. 
   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.