Abstract:
There is provided a power supply apparatus supplying driving power. The power supply apparatus includes: a first power converter bypassing input power when a voltage level of the input power having a predetermined voltage level is within a reference voltage level range, and converting the input power to DC power having a preset voltage level when the voltage level of the input power is outside of the reference voltage level range; and a second power converter converting the power inputted from the first power converter to driving power having a preset voltage level.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims the priority of Korean Patent Application No. 2011-0051373 filed on May 30, 2011, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND OF THE INVENTION 
       [0002]    1. Field of the Invention 
         [0003]    The present invention relates to a power supply apparatus for supplying driving power. 
         [0004]    2. Description of the Related Art 
         [0005]    In general, in order to drive electronic devices, a power supply apparatus for supplying driving power necessary for the operation of the electronic apparatus is required. 
         [0006]    A power supply apparatus usually converts commercial alternating current (AC) power into direct current (DC) power to supply the DC power to the electronic apparatus as driving power. A power conversion circuit directly converts commercial AC power to driving power. However, a voltage level thereof, at which relatively high power conversion efficiency can be maintained, is limited, and thus, it may be difficult to maintain high power conversion efficiency with respect to a wide input voltage level range. In addition, when multi-stage power conversion is performed, the power conversion is performed through several stages, causing power conversion efficiency to be lowered. 
       SUMMARY OF THE INVENTION 
       [0007]    An aspect of the present invention provides a power supply apparatus capable of bypassing input power of a predetermined voltage range or converting it to a predetermined voltage depending on a voltage range of the input power at the time of multi-stage power conversion. 
         [0008]    According to an aspect of the present invention, there is provided a power supply apparatus, including: a first power converter bypassing input power when a voltage level of the input power having a predetermined voltage level is within a reference voltage level range, and converting the input power to DC power having a preset voltage level when the voltage level of the input power is outside of the reference voltage level range; and a second power converter converting the power inputted from the first power converter to driving power having a preset voltage level. 
         [0009]    The power supply apparatus may further include a controller stopping an operation of the first power converter to bypass the input power to the second power converter when the voltage level of the input power is within the reference voltage level range, and resuming a power conversion operation of the first power converter when the voltage level of the input power is outside of the reference voltage level range. 
         [0010]    The first power converter maybe a buck converter having a voltage range from a minimum voltage level of the voltage level range of the input power to the voltage level of the DC power as the reference voltage level range. 
         [0011]    The first power converter may be a boost converter having the voltage range from a voltage level of the DC power to a maximum voltage level of the voltage level range of the input power as the reference voltage level range. 
         [0012]    The second power converter may be an inductor-inductor-capacitor (LLC) resonant converter having a maximum resonance point at the voltage level of the DC power. 
         [0013]    The power supply apparatus may further include a power factor corrector rectifying and power factor correcting commercial AC power to supply the rectified and corrected power as the input power. 
         [0014]    The second power converter may be a phase-shifted full-bridge (PSFB) converter. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]    The above and other aspects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0016]      FIG. 1  is a schematic block diagram of a power supply apparatus of the present invention; 
           [0017]      FIGS. 2A and 2B  are schematic circuit block diagrams of a power supply apparatus according to an embodiment of the present invention; and 
           [0018]      FIG. 3  is a schematic circuit block diagram of a power supply apparatus according to another embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0019]    Embodiments of the present invention will now be described in detail with reference to the accompanying drawings. 
         [0020]    The present invention should not be construed as being limited to the embodiments set forth herein and the embodiments detailed herein may be used to assist in understanding the technical idea of the present invention. Like reference numerals designate like components having substantially the same constitution and function in the drawings of the present invention. 
         [0021]      FIG. 1  is a schematic block diagram of a power supply apparatus according to an embodiment of the present invention. 
         [0022]    Referring to  FIG. 1 , a power supply apparatus  100  according to an embodiment of the present invention may include a first power converter  110 , a second power converter  120 , and a controller  130 . 
         [0023]    The first power converter  110  may convert a voltage level of input power. Here, the voltage level of the input power may be within a predetermined voltage level range, and the input power may be DC power. 
         [0024]    The first power converter  110  may set a reference level range having a preset voltage level range, and may transmit the input power to the second power converter  120  when the voltage level of the input power is within the reference level range. 
         [0025]    The first power converter  110  may convert the input power to DC power having a preset voltage level to transmit the DC power to the second power converter  120  when the voltage level of the input power is outside of the reference level range. 
         [0026]    The second power converter  120  may convert the power inputted from the first power converter  110  to driving power Vo having a preset voltage level. 
         [0027]    In other words, when the voltage level of the input power is within the reference level range, the first power converter  110  may bypass the input power and the second power converter  120  may convert the voltage level of the input power to output the driving power Vo. When the voltage level of the input power is outside of the reference level range, the first power converter  110  may transmit the DC power to the second power converter  120 , and the second power converter  120  may convert the voltage level of the DC power to output the driving power Vo. 
         [0028]    The controller  130  may detect the voltage level of the input power to determine whether or not the voltage level of the input power is within the reference level range. 
         [0029]    The controller  130  may control the first power converter  110  to stop a power conversion operation thereof and to bypass the input power to the second power converter  120  when the voltage level of the input power is within the reference level range, and may control the first power converter  110  to perform the power conversion operation thereof when the voltage level of the input power is outside of the reference level range. 
         [0030]      FIGS. 2A and 2B  are schematic circuit block diagrams of a power supply apparatus according to an embodiment of the present invention. 
         [0031]    Referring to  FIG. 2A , in a power supply apparatus  200  according to an embodiment of the present invention, the first power converter  110  shown in  FIG. 1  may be a buck converter  210  of lowering the voltage level of the input power, and the second power converter  120  shown in  FIG. 1  may be an LLC resonant converter  220  having a preset maximum resonance point. The LLC resonant converter  220  may include a transformer converting power, and may use leakage inductance and magnetizing inductance of the transformer, and resonance between capacitors connected to the transformer, for power conversion. The controller  130  shown in  FIG. 1  may perform the same function in the power supply apparatus according to one embodiment of the present invention, and thus, drawing and description thereof will be omitted. 
         [0032]    For example, in a case in which the voltage level of the input power is 42V to 75V, the reference level range may be 42V to 49V. That is, in a case in which the voltage level of the input power is 42V to 49V, the buck converter  210  may stop operation of first and second switches Q 1  and Q 2  and an inductor L by control of the controller  130 , thereby allowing the voltage level of the input power to be transmitted to the LLC resonant converter  220 . 
         [0033]    Here, the LLC resonant converter  220  may set a maximum resonance point to have a maximum resonance frequency at 49V of the voltage level from the buck converter  210 . Since a method of setting a maximum resonance point in the LLC resonance converter  220  is known generally, detailed description thereof will be omitted. 
         [0034]    Meanwhile, a maximum resonance point is generally set to a maximum voltage level of the inputted voltage level in the LLC resonant converter  220 , but in the power supply apparatus  200  according to one embodiment of the present invention, the voltage level of the input power is varied by the buck converter  210 , and then a maximum resonance point may be set to a maximum voltage level of the varied voltage level. 
         [0035]    Therefore, when input power having a voltage level of 49V to 72V is inputted, the buck converter  210  may perform a lowering operation to transmit DC power having a voltage level of 49V, which is set as a maximum resonance point, to the LLC resonant converter  220 , thereby maintaining relatively high power conversion efficiency of the LLC resonant converter  220 . 
         [0036]    Referring to  FIG. 2B , in a case in which the voltage level of the input power is 48V, the voltage level of the input power is within the reference level range, and thus, the voltage of 48V may be transmitted to the LLC resonant converter  220 , as it is. The voltage level of the DC power transmitted to the LLC resonant converter  220  is 48V, which is lower than 49V that is the voltage level of a maximum resonance point. However, since a difference therebetween is not great, power conversion efficiency of the LLC resonant converter  220  can be maintained high. For example, the situation is the same for a case in which the voltage level of the input power is 42V. 
         [0037]    That is, when the buck converter  210  is employed, the voltage level of a maximum resonance point in the LLC resonant converter  220  maybe set to near a minimum voltage of the voltage level of the input power, thereby maintaining high power conversion efficiency of the LLC resonant converter  220  even at a voltage level within the reference level range, and the LLC resonant converter  220  is operated at a maximum resonance point at the voltage level being outside of the reference level range, thereby maintaining relatively high power conversion efficiency. 
         [0038]    In addition, in the buck converter  210  as shown in  FIGS. 2A and 2B , the first switch Q 1  may gradually charge the DC power transmitted to the LLC resonant converter  220 , and thus, it can be substituted for a switch of a hot swap bock, and the inductor L increases switching frequency to decrease a size thereof, and thus, a circuit occupation area of the buck converter  210  can be significantly reduced. 
         [0039]      FIG. 3  is a schematic circuit block diagram of a power supply apparatus according to another embodiment of the present invention. 
         [0040]    Referring to  FIG. 3 , a power supply apparatus  300  according to another embodiment of the present invention may employ a power factor corrector  310  for correcting a power factor by receiving a commercial AC power, rectifying the commercial AC power, and adjusting phase difference between voltage and current of the rectified power. 
         [0041]    Referring to  FIG. 3 , in the power supply apparatus  300  according to another embodiment of the present invention, the first power converter  110  shown in  FIG. 1  may be a boost converter  320  boosting the voltage level of the input power, and the second power converter  120  shown in  FIG. 1  may be a phase-shifted full-bridge (PSFB) converter  330 . Since a controller  340  shown in  FIG. 3  performs the same function as the controller  130  shown in  FIG. 1 , detailed description thereof will be omitted. 
         [0042]    For example, in a case in which the voltage level of the input power, which is power factor corrected by the power factor corrector  310  and then transmitted to the boost converter  320 , is 320V to 400V, the reference level range may be 390V to 400V. That is, when the voltage level of the input power is 390V to 400V, the boost converter  320  may stop operation of first and second switches Q 1  and Q 2  and an inductor L according to control of the controller  340 , to allow the voltage level of the input power to be transmitted to the phase-shifted full-bridge converter  330 . Whereas, when the voltage level of the input power is 320V to 390V, the boost converter  320  may boost the voltage level to 390V and then transmit the boosted voltage level to the phase-shifted full-bridge converter  330 . 
         [0043]    Here, the phase-shifted full-bridge converter  330  may adjust duty of each switch of full bridge according to the voltage level of the input power, to output driving power having a preset voltage level. Since a method in which the duty of each switch of full bridge according to the voltage level of the input power is adjusted in the phase-shifted full bridge converter  330  is generally known, detailed description thereof will be omitted. 
         [0044]    However, in the power supply apparatus  300  according to another embodiment of the present invention, the boost converter  320  may reduce the voltage level range of the input power and transmit the reduced voltage to the phase-shifted full-bridge converter  330 , and the phase-shifted full-bridge converter  330  maybe operated at almost a maximum duty, thereby maintaining the power conversion efficiency near to relatively high power conversion efficiency. 
         [0045]    As described above, according to embodiments of the present invention, a predetermined voltage range of the input power may be bypassed, or converted to a preset voltage, according to the voltage level of the input power at the time of multi-stage power conversion, and then transmitted to the LLC converter or the PSFB converter at the rear, to allow the LLC converter or the PSFB converter to be operated at near to a maximum operation point at which relatively high power conversion efficiency can be maintained, thereby maintaining high power conversion efficiency even though the voltage level of the input power is varied. 
         [0046]    As set forth above, according to embodiments of the invention, a predetermined voltage range of the input power is bypassed, or converted to a preset voltage, according to the voltage level of the input power at the time of multi-stage power conversion, thereby maintaining relatively high power conversion efficiency of the LLC converter or the PSFB converter provided at the rear. 
         [0047]    While the present invention has been shown and described in connection with the embodiments, it will be apparent to those skilled in the art that modifications and variations can be made without departing from the spirit and scope of the invention as defined by the appended claims.