Abstract:
There is provided a power supply device having a primary side and a secondary side isolated from each other. The power supply device includes: a power supply unit converting power from the primary side to output the converted power to the secondary side; a control unit located on the secondary side and acquiring control information on the power supply unit based on a voltage output from the power supply unit; and a delivery unit delivering the control information to the primary side, the delivery unit including a Y-capacitor that provides an EMI noise path between the primary side and the secondary side.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims the benefit of Korean Patent Application No. 10-2013-0123984 filed on Oct. 17, 2013, with the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference. 
       BACKGROUND 
       [0002]    The present disclosure relates to a power supply device. 
         [0003]    In general, a switched-mode power supply (SMPS) is frequently used as a power supply device, since it is relatively small yet has high efficiency. Such a power supply device serves to supply a direct current (DC) voltage as required by a system from mains electricity. Typically, an electronic device used in the home or the office enters a normal mode in which power is normally supplied while it is actually used, and enters a standby mode in which it waits for an operation event while it is in an idle state or is not being used. 
         [0004]    Power consumed in the standby mode is wasteful, and thus, various approaches to reducing power consumption in the standby mode have been proposed. 
         [0005]    On the other hand, as types of electronic devices, such as mobile devices and portable multimedia devices have recently been diversified, various types of power conversion devices are required. In addition, while existing power conversion devices only need to stably supply power to a load, recent power conversion devices have to meet various other requirements. 
         [0006]    Accordingly, in order to adapt to ever more complicated device structures and to meet various requirements, a novel power conversion device having improved performance and efficiency, with a reduced size, and having price competitiveness is required. 
       RELATED ART DOCUMENTS 
       [0007]    (Patent Document 1) Japanese Patent No. 5152185 
         [0008]    (Patent Document 2) Korean Patent Laid-open Publication No. 2002-0008668 
       SUMMARY 
       [0009]    An aspect of the present disclosure may provide a power supply device capable of reducing power consumption in a standby mode. 
         [0010]    An aspect of the present disclosure may also provide a power supply device capable of accurately regulating an output voltage. 
         [0011]    An aspect of the present disclosure may also provide a power supply device able to be reduced in size at low cost. 
         [0012]    According to an aspect of the present disclosure, a power supply device having a primary side and a secondary side isolated from each other may include: a power supply unit converting power from the primary side to output the converted power to the secondary side; a control unit located on the secondary side and acquiring control information on the power supply unit based on a voltage output from the power supply unit; and a delivery unit delivering the control information to the primary side, the delivery unit including a Y-capacitor that provides an EMI noise path between the primary side and the secondary side. 
         [0013]    The power supply device may further include: a driving unit located on the primary side, acquiring the control information from the delivery unit, and driving a switching element, the switching element being included in the power supplying unit and allowing and disallowing a primary current to flow through the primary side. 
         [0014]    The delivery unit may include a capacitor element, a resistor element, and a diode element, wherein the resistor element is electrically connected between one terminal of the capacitor element and one terminal of the Y-capacitor element, the one terminal of the capacitor element is electrically connected to an anode of the diode element, and the other terminal of the Y-capacitor element is grounded. 
         [0015]    The delivery unit may include: a first deliverer delivering first transition information from the control unit to instruct transition from a low level to a high level, and a second deliverer delivering second transition information from the control unit to instruct transition from the high level to the low level. 
         [0016]    The first deliverer may include a first capacitor element, a first resistor element, and a first diode element, wherein the first resistor element is electrically connected between one terminal of the first capacitor element and one terminal of the Y-capacitor element, the one terminal of the first capacitor element is electrically connected to an anode of the first diode element, and the other terminal of the Y-capacitor element is grounded. 
         [0017]    The second deliverer may include a second capacitor element, a second resistor element, and a second diode element, wherein the second resistor element is electrically connected between one terminal of the second capacitor element and one terminal of the Y-capacitor element, the one terminal of the second capacitor element is electrically connected to an anode of the second diode element, and the other terminal of the Y-capacitor element is grounded. 
         [0018]    The power supply device may further include: a driving unit located on the primary side, acquiring the first and second transition information from the delivery unit, and driving the switching element based on the first and second transition information. 
         [0019]    According to another aspect of the present disclosure, a power supply device may include: a power supply unit having a primary side and a secondary side, and a primary winding formed on the primary side and a secondary winding formed on the secondary side and inductively coupled to the primary winding, the power supplying unit including a Y-capacitor providing an EMI noise path between the primary side and the secondary side; a control unit located on the secondary side and acquiring control information on the power supply unit based on a voltage output from the power supply unit; and a delivery unit having a high-pass filter including the Y-capacitor and delivering the control information to the primary side. 
         [0020]    The power supply device may further include: a driving unit located on the primary side, acquiring the control information from the delivery unit, and driving a switching element, the switching element allowing and disallowing a primary current to flow through the primary side. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0021]    The above and other aspects, features and other advantages of the present disclosure will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: 
           [0022]      FIG. 1  is a block diagram of atypical isolated converter; 
           [0023]      FIG. 2  is a diagram illustrating a flyback converter according to an exemplary embodiment of the present disclosure; and 
           [0024]      FIG. 3  is a diagram showing an example of waveforms from units shown in the block diagram of  FIG. 2 . 
       
    
    
     DETAILED DESCRIPTION 
       [0025]    Hereinafter, embodiments of the present disclosure will be described in detail with reference to the accompanying drawings. The disclosure may, however, be embodied in many different forms and should not be construed as being limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art. Throughout the drawings, the same or like reference numerals will be used to designate the same or like elements. 
         [0026]    For the convenience of illustration, the configuration of a power supply device will be described in terms of a flyback converter in this specification. 
         [0027]    As will be appreciated by those skilled in the art, however, the configurations according to exemplary embodiment of the present disclosure may be applied to a forward converter, a half-bridge converter, a full-bridge converter, a push-pull converter, a resonant converter or the like. 
         [0028]      FIG. 1  is a block diagram of a typical isolated converter. 
         [0029]    Referring to  FIG. 1 , the isolated converter may include a converter unit  100 , a voltage detection unit  200 , a photo-coupler  300 , and a control unit  400 . 
         [0030]    The converter unit  100  may be configured based on a typical isolated converter topology. 
         [0031]    Typically, the converter unit may include a primary side on which a primary winding is located and a secondary side on which a secondary winding, inductively coupled to the primary winding, is located. 
         [0032]    The converter unit may receive an input power INPUT and may convert it to output an output voltage OUTPUT. 
         [0033]    The voltage detection unit  200  may detect the output voltage OUTPUT. 
         [0034]    The photo-coupler  300  may transmit information on the output voltage OUTPUT detected from the secondary side to the control unit  400  located on the primary side. 
         [0035]    The control unit  400  may control the converter unit  100  based on the information on the output voltage OUTPUT. Specifically, the control unit  400  may output a control signal for controlling the converter unit  100 . 
         [0036]    In the power supply device thus configured, in order to ensure the stable operation of the voltage detection unit  200  and the driving of the photo-coupler, the level of the current flowing on the secondary side needs to be maintained above a certain level. Therefore, power is constantly consumed in the voltage detection unit  200 , the photo-coupler  300  and peripheral circuits. 
         [0037]    Recently, a very low level of power consumption in the standby mode is required, and thus the power supply device described above may not meet the requirements of power consumption in the standby mode. 
         [0038]    In response to such requirements of power consumption in the standby mode, a primary side regulation (PSR) type power supply device has recently been provided. 
         [0039]    The PSR type power supply device may detect voltage induced in the secondary winding of a transformer to drive a converter based on the detected voltage. 
         [0040]    The PSR type power supply device may eliminate a voltage detecting unit, a photo-coupler, and peripheral circuits, so that power consumption may be reduced. 
         [0041]    The PSR type power supply device, however, has a problem in that it may not accurately regulate an output voltage when a load is rapidly increased from a standby mode (no-load condition). Further, when this happens, a larger voltage drop occurs. 
         [0042]    Further, output voltage is not directly detected by a power supply device but is indirectly detected using the secondary winding, the output voltage may not accurately regulated. 
         [0043]      FIG. 2  is a diagram illustrating a flyback converter according to an exemplary embodiment of the present disclosure. 
         [0044]    Referring to  FIG. 2 , the flyback converter may include a voltage source Vin, a transformer  20 , a rectifying unit  10 , a switching element  30 , a control unit  40 , a rectifying diode D 1 , a delivery unit  50 , and a driving unit  60 . 
         [0045]    The voltage source Vin may supply input voltage. The input voltage may be alternating current (AC) voltage. 
         [0046]    The rectifying unit  10  may receive and rectify AC voltage to transmit it to the transformer  20 . 
         [0047]    The transformer  20  may include a primary winding and a secondary winding inductively coupled to the primary winding. Herein, a primary side refers to the region in which the primary winding is located, and a secondary side refers to the region in which the secondary winding is located. 
         [0048]    The transformer  20  may convert primary current I 1  from the voltage source into secondary current I 2 . 
         [0049]    The switching element  30  may allow or disallow the primary current I 1  to flow through the primary winding of the transformer. 
         [0050]    The switching element  30  may be implemented as one of an insulated gate bipolar transistor (IGBT), a metal oxide semiconductor field-effect transistor (MOS-FET), and a bipolar junction transistor (BJT). 
         [0051]    The rectifying diode D 1  may rectify the second current I 2  of the transformer  20 . 
         [0052]    A capacitor element Co may stabilize the voltage transmitted from the rectifying diode D 1 . 
         [0053]    The control unit  40  may acquire output voltage information Vo. 
         [0054]    The control unit  40  may acquire control information on the switching element  30  based on the output voltage information Vo. 
         [0055]    The control unit  40  may be located on the secondary side. 
         [0056]    According to an exemplary embodiment of the present disclosure, the control unit  40  is located on the secondary side, so that output voltage may be directly detected and accurately regulated. 
         [0057]      FIG. 3  is a diagram showing an example of waveforms from units shown in the block diagram of  FIG. 2 . 
         [0058]    Referring to  FIG. 3 , the control unit  40  may acquire control information Q req . In order to transmit the control information Q req  the control unit  40  may output first transition information Ss to instruct transition from a low level to a high level, and second transition information S r  to instruct transition from the high level to the low level. 
         [0059]    The delivery unit  50  may deliver the control information to the driving unit  60  located on the primary side. 
         [0060]    The delivery unit  50  may include a Y-capacitor Cy that provides an EMI noise path between the primary and secondary sides. 
         [0061]    Specifically, the delivery unit  50  may include a first deliverer that delivers the first transition information from a low level to a high level, and a second deliverer that delivers the second transition information from the high level to the low level. 
         [0062]    The first deliverer may include a first capacitor element Cs, a first resistor element Rs, a first diode element Ds, and a Y-capacitor element Cy. 
         [0063]    Referring to  FIG. 2 , the first resistor element Rs may be electrically connected between one terminal of the first capacitor element Cs and one terminal of the Y-capacitor element Cy, the terminal of the first capacitor element Cs may be electrically connected to the anode of the first diode element Ds, and the other terminal of the Y-capacitor element Cy may be grounded. The other terminal of the first capacitor element Cs may be connected to the control unit  40 , and the cathode of the first diode element Ds may be connected to the driving unit  60 . 
         [0064]    With this configuration, the first deliverer may operate as a high-pass filter. Further, the first deliverer may output transition information S set  from a low level to a high level. 
         [0065]    The second deliverer may include a second capacitor element Cr, a second resistor element Rr, a second diode element Dr, and the Y-capacitor. 
         [0066]    Referring to  FIG. 2 , the second resistor element Rr may be electrically connected between one terminal of the second capacitor element Cr and one terminal of the Y-capacitor element Cy, and the terminal of the second capacitor element Cr may be electrically connected to the anode of the second diode element Dr. The other terminal of the second capacitor element Cr may be connected to the control unit  40 , and the cathode of the second diode element Dr may be connected to the driving unit  60 . 
         [0067]    With this configuration, the second deliverer may operate as a high-pass filter. Further, the second deliverer may output transition information S reset  from the high level to the low level. 
         [0068]    That is, the deliver unit  50  according to an exemplary embodiment of the present disclosure may configure a high-pass filer using the Y-capacitor used as an EMI noise path between the primary side and the secondary side of a converter, to deliver the control information acquired by the control unit  40  to the driving unit  60  located on the primary side. 
         [0069]    A pulse transformer (PT) is commonly used for delivering a signal between isolated regions. 
         [0070]    In case that such a PT is located between the primary side and the secondary side of an isolated converter, there is a drawback that the size of the PT is very large in order to sufficiently isolate the primary side from the secondary side. 
         [0071]    In contrast, the power supply device according to an exemplary embodiment of the present disclosure realizes the delivery of a signal between isolated regions using only the Y-capacitor, the resistor elements, the capacitor elements, and the diode elements, which are essential elements in providing an EMI noise path in a converter. 
         [0072]    Therefore, the power supply device according to an exemplary embodiment of the present disclosure is very advantageous in terms of price and size. Further, the delivery unit according to an exemplary embodiment of the present disclosure may be easily applied to a semiconductor IC. 
         [0073]    If a signal is to be delivered between the primary side and the secondary side of the power supply device, the signal may be delivered by virtue of the delivery unit  50 . 
         [0074]    The driving unit  60  may acquire control information from the delivery unit  50 . Specifically, the driving unit  60  may acquire first transition information S set  and second transition information S reset  from the delivery unit  50  and to obtain control information Q req  based thereon. 
         [0075]    As can be seen from  FIG. 3 , the driving unit  60  may output a driving signal Q identical to the control information Q req  based on the first transition information S set  and the second transition information S reset . 
         [0076]    The driving unit  60  may output the driving signal Q so as to control the switching element  30 . 
         [0077]    Further, the control unit  60  may be located on the primary side. 
         [0078]    According to an exemplary embodiment of the present disclosure, the driving unit may be implemented as a set-reset (SR) flip-flop. For example, the first transition information S set  may be a set signal to a SR flip-flop, and the second transition information S reset  may be a reset signal to the SR flip-flop. 
         [0079]    In this way, the driving unit  60  may output the driving signal based on the control information acquired by the control unit  40  to the switching element  30 . 
         [0080]    The power supply device according to an exemplary embodiment of the present disclosure may significantly save power consumption in the standby mode, compared to a typical flyback converter using a photo-coupler. 
         [0081]    Further, the power supply device according to an exemplary embodiment of the present disclosure may control output voltage more accurately than a PSR type converter. Additionally, the power supply device according to an exemplary embodiment of the present disclosure may overcome the problem of voltage drop arising in a PSR type converter when a load is rapidly changed. 
         [0082]    Moreover, the power supply device according to an exemplary embodiment of the present disclosure may realize the delivery of a signal between isolated regions using only the Y-capacitor, the resistor elements, the capacitor elements, and the diode elements, which are essential elements in a converter to provide an EMI noise path, such that cost may be saved and size may be reduced. 
         [0083]    As set forth above, according to exemplary embodiments of the present disclosure, a power supply device capable of reducing power consumption in a standby mode may be provided. 
         [0084]    Further, according to exemplary embodiments of the present disclosure, a power supply device capable of accurately regulating an output voltage may be provided. 
         [0085]    Furthermore, according to exemplary embodiments of the present disclosure, a power supply device may be provided with reduced size at low cost. 
         [0086]    While exemplary embodiments have been shown and described above, it will be apparent to those skilled in the art that modifications and variations could be made without departing from the spirit and scope of the present disclosure as defined by the appended claims.