Patent Publication Number: US-2023155406-A1

Title: Load sharing control device

Description:
TECHNICAL FIELD 
     The present invention relates to a load sharing control device, and more particularly, to a load sharing control device and a load sharing control circuit capable of power derating. 
     BACKGROUND ART 
     In general, a power supply system is configured by connecting a plurality of power supply devices in parallel in order to stably supply power. In the case of using a plurality of power supplies, there are advantages in heat generation, reliability, redundancy, and modularization compared to the case of using a single power supply. 
     In a power supply system using a plurality of power supplies, a load sharing controller is built in so as to distribute load uniformly between each power supply. At this time, it is necessary to design a load sharing controller capable of stable operation in various operation modes such as independent operation and constant current-constant voltage (CC-CV) operation when power is supplied using a plurality of power supply devices. 
     DETAILED DESCRIPTION OF THE INVENTION 
     Technical Subject 
     The technical problem to be solved by the present invention is to provide a load sharing control device and a load sharing control circuit capable of power derating. 
     The problems of the present invention are not limited to the problems mentioned above, and other problems not mentioned will be clearly understood by those skilled in the art from the following description. 
     Technical Solution 
     In order to solve the above technical problem, a load sharing control device according to an embodiment of the present invention, in a load sharing control device included in each of multiple power supply devices being connected to a load in parallel, comprises: a first control unit for generating a first control signal which controls an output current of a power supply device, by using the output current of the power supply device and a current of a load share bus; and a second control unit for generating a second control signal which controls an output voltage of the power supply device, by using a target voltage of the power supply device, a feedback voltage received as feedback from the output voltage of the power supply device, and a control voltage according to the first control signal of the first control unit, wherein the first control unit generates the first control signal so that the output current is identical to the current of the load share bus, and limits the output current to a threshold current or less. 
     In addition, the first control unit may comprise: a first comparison unit for comparing the output current with the current of the load share bus; a first calculation unit for calculating the difference between the output current and the current of the load share bus; and a current control unit for generating the first control signal according to the output of the first calculation unit. 
     In addition, the current control unit may generate the first control signal for controlling the level of the feedback voltage being inputted to the second control unit. In addition, the first control unit may include a second comparison unit for comparing the output current and the threshold current. 
     In addition, the second control unit may comprise: a second calculation unit for calculating a difference between the feedback voltage and a control voltage according to the first control signal; a third calculation unit for calculating the difference between the target voltage and the output of the second calculation unit; and a voltage control unit for generating a second control signal for controlling the output voltage of the power supply device according to the output of the third calculation unit. 
     In addition, at least one of the target voltage and the threshold current may be adjusted according to the limited power of the power supply device. 
     In order to solve the above technical problem, a load sharing control device according to an embodiment of the present invention, in a load sharing control device included in each of multiple power supply devices being connected to a load in parallel and including a CV circuit or CC-CV circuit, comprises: a maximum current output circuit unit for outputting a larger voltage among an output current sensing voltage sensing an output current of the power supply device and a voltage of a load share bus; a minimum current output circuit unit for outputting a smaller voltage among an output of the maximum current output circuit unit and a voltage according to a threshold current; and an amplification unit for amplifying the difference between the output current sensing voltage and the output of the minimum current output circuit unit and applying it to a CV feedback terminal of the CV circuit or the CC-CV circuit. 
     In addition, the threshold current may be a preset value or a value obtained by subtracting a predetermined value from the reference current of the CC-CV circuit. 
     In addition, the maximum current output circuit unit may comprise: a first comparator receiving the output sensing voltage via the positive (+) input terminal and receiving the voltage of the load share bus via the negative (−) input terminal; and a first diode to which the output end of the first comparator and the anode are connected, and the voltage of the load share bus and the cathode are connected. 
     In addition, the minimum current output circuit unit may include: a second comparator receiving a voltage according to the threshold current via the positive (+) input terminal and receiving an output of the maximum current output circuit unit via the negative (−) input terminal; and a second diode to which the output end of the second comparator and the cathode are connected, and the voltage of the load share bus and the anode are connected. 
     In addition, the amplification unit may include: a transconductance amplifier for amplifying a difference between the output current sensing voltage and an output of the minimum current output circuit unit; and a first amplifier for amplifying an output of the transconductance amplifier; and a transistor to which an output terminal of the first amplifier is connected to a base, a negative input terminal of the first amplifier is connected to an emitter, and the CV feedback terminal and a collector are connected. 
     In addition, the transconductance amplifier may have a predetermined offset voltage. 
     In addition, it may include a second amplifier for sensing and amplifying the output current to output the output current sensing voltage. 
     In addition, at least one among the reference voltage of the CC-CV circuit, the reference voltage of the CV circuit, or the threshold current may be adjusted according to the limited power of the power supply device. 
     In addition, when the load includes a battery, it may be connected to the CC-CV circuit. 
     Advantageous Effects 
     According to embodiments of the present invention, while performing load sharing control, independent operation and redundancy are possible, and power derating is possible. 
     In addition, load sharing is possible in all sections of CC-CV even when the battery load is connected, and even if the output is shorted, the CC control circuit operates so that the device can be protected. 
     The effect according to the invention is not limited by the contents exemplified above, and more various effects are included in the present specification. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a block diagram of a load sharing control device according to an embodiment of the present invention. 
         FIGS.  2  to  8    are diagrams for explaining the function of the load sharing control device according to an embodiment of the present invention. 
         FIG.  9    is a block diagram of a first control unit of a load sharing control device according to an embodiment of the present invention. 
         FIG.  10    is a block diagram of a second control unit of a load sharing control device according to an embodiment of the present invention. 
         FIG.  11    illustrates an implementation example of a load sharing control device according to an embodiment of the present invention. 
         FIGS.  12  to  13    are diagrams for explaining the operation of each case of the load sharing control device according to an embodiment of the present invention. 
         FIG.  14    is a circuit diagram of a load sharing control circuit according to an embodiment of the present invention. 
         FIGS.  15  to  17    are diagrams for explaining the operation of each case of the load sharing control circuit according to an embodiment of the present invention. 
         FIG.  14    is a circuit diagram of a load sharing control circuit according to another embodiment of the present invention. 
     
    
    
     BEST MODE 
     Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. 
     However, the technical idea of the present invention is not limited to some embodiments to be described, but may be implemented in various forms, and within the scope of the technical idea of the present invention, one or more of the constituent elements may be selectively combined or substituted between embodiments. 
     In addition, the terms (including technical and scientific terms) used in the embodiments of the present invention, unless explicitly defined and described, can be interpreted as a meaning that can be generally understood by a person skilled in the art, and commonly used terms such as terms defined in the dictionary may be interpreted in consideration of the meaning of the context of the related technology. 
     In addition, terms used in the present specification are for describing embodiments and are not intended to limit the present invention. 
     In the present specification, the singular form may include the plural form unless specifically stated in the phrase, and when described as “at least one (or more than one) of A and B and C”, it may include one or more of all combinations that can be combined with A, B, and C. 
     In addition, in describing the components of the embodiment of the present invention, terms such as first, second, A, B, (a), and (b) may be used. These terms are merely intended to distinguish the components from other components, and the terms do not limit the nature, order or sequence of the components. 
     And, when a component is described as being ‘connected’, ‘coupled’ or ‘interconnected’ to another component, the component is not only directly connected, coupled or interconnected to the other component, but may also include cases of being ‘connected’, ‘coupled’, or ‘interconnected’ due that another component between that other components. 
     In addition, when described as being formed or arranged in “on (above)” or “below (under)” of each component, “on (above)” or “below (under)” means that it includes not only the case where the two components are directly in contact with, but also the case where one or more other components are formed or arranged between the two components. In addition, when expressed as “on (above)” or “below (under)”, the meaning of not only an upward direction but also a downward direction based on one component may be included. 
       FIG.  1    is a block diagram of a load sharing control device according to an embodiment of the present invention. 
     The load sharing control device according to an embodiment of the present invention is included in each of a plurality of power supply devices connected in parallel to a load, and performs load sharing for equally controlling each output current of the plurality of power supply devices. Here, the power supply device is a PSU, which is a device that supplies power to load, and it may be a device for supplying power for servers, supplying DC-DC power for vehicles, or supplying DC-DC power for DC distribution systems. In addition, it is natural that various devices for supplying power may be included. 
     The load sharing control device included in each power supply device  300  comprises a first control unit  100  and a second control unit  200 . Load sharing is performed using a first control signal  104  being generated by the first control unit  100  and the second control signal  203  being generated by the second control unit  200 , but supply power can be limited. 
     In order to efficiently and stably use the plurality of power supply devices  300 , it is necessary to perform various functions. 
     In the case of using a plurality of power supply devices, as shown in  FIG.  2   , the power supply devices are connected in parallel to each other. At this time, redundancy must be performed for efficient operation. Redundancy means maintaining system output by operating another power supply device when a defect or failure occurs in a certain power supply. In addition, as shown in the graph of  FIG.  2   , the light load efficiency can be maximized by sequentially driving the power supply device according to the system output load. As shown in  FIG.  2   , efficiency can be increased by driving: power supply device 1 (PSU #1) up to 60% of the load, power supply device 2 (PSU #2) up to 60 to 110%, power supply device 3 (PSU #3) up to 110 to 160%, and power supply device 4 (PSU #4) up to 160% or more. 
     In addition, as shown in  FIG.  3   , it is necessary to perform load sharing. Load sharing is to control the current being outputted from each power supply device to be the same, and when power supply device 1 (PSU #1) to power supply device 3 (PSU #3) are operated, the system load current I is 11+I2+I3, and load sharing is performed so that I1=I2=I3 through load sharing. After that, when power supply device 4 (PSU #4) is driven, I4 is 0 before driving, and when load sharing is performed so that I1=I2=I3=I4 through load sharing, the value of each current decreases, however, the overall system load current remains the same. After that, when the system load increases, by increasing the value of each current, it is controlled to increase the overall system load current. 
     All power supply devices each include an output voltage control device, and there may be a slight difference between the output target voltages due to the deviation of the circuit component characteristics (other than the resistance value) of each output voltage control device, as shown in  FIG.  4   . In this state, when the outputs of the respective power supply devices are connected in parallel, the system output voltage is controlled to the highest target voltage, and therefore, the power supply device 1 (PSU #1) with the highest target voltage controls the output, and the remaining power supply devices 2, 3, and 4 (PSUs #2, #3, and #4) have an output voltage higher than the target voltage of each power supply device, so that their duty ratio is reduced by each output voltage control device. As a result, power supply to the power supply devices 2, 3, and 4 (PSUs #2, #3, and #4) is reduced, and power supply is concentrated to the power supply device 1 (PSU #1), and thereby occurring a current imbalance. In order to resolve this imbalance, load sharing is necessary. 
     For load sharing, as shown in  FIG.  5   , a load share bus (load share bus) line is added to the outside of the power supply device and connected, and a load share controller is added inside. Here, the highest output current information among the individual output currents of each power supply device is delivered to the load share bus, and in order to deliver the maximum current through the load share bus, each load share control unit includes a comparator  41  for comparing each output current with the current of the load share bus, and may include a diode  42  for delivering the corresponding output current to the load share bus when the corresponding current is the maximum current. The detected voltage on each output current is applied to the positive (+) input terminal of the comparator  41 , and a voltage including the maximum current information is applied to the negative (−) input terminal; when the output current is greater than the maximum current, a high is outputted as an output of the comparator  42  to turned on the diode so that the output current is delivered to the load share bus and the output current is delivered to the other power supply device as a maximum current. When the output current is less than the maximum current, the maximum current is maintained. 
     When a current imbalance occurs and the output current is lower than the maximum current of the load share bus, the duty ratio is increased by lowering the output voltage feedback signal, and thereby the output current increases, and eventually, the output current increases to become equal to the maximum current. This state can be referred to as a steady-state. Control of the feedback voltage of the output voltage to the output voltage control device is not performed when the target voltage and the output voltage are the same in the stable state where the output current is the same as the maximum current. However, even when the target voltage is lower than the output voltage in the stable state, that is, when the output voltage is 12 V in FIG. 4 and the output is controlled by the power supply device 1 (PSU #1), in order to do load sharing, the feedback voltage of the output voltage to the output voltage control device is lowered, and thereby preventing the duty ratio from being lowered. Through this, supply of power is not concentrated in one power supply device, and load sharing becomes possible. 
       FIG.  6    illustrates a constant current-constant voltage (CC-CV) circuit, and serves to prevent the output voltage and current from becoming excessively high. When the output voltage Vout is lower than the reference voltage Vref, the output of the comparator  61  goes high, thereby opening the diode  62 . In addition, when the output current lout is lower than the reference current Iref, the output of the comparator  64  becomes high, and the diode  63  is opened. That is, Vcc is applied to the control signal voltage Vc for controlling the duty ratio of the power supply device to increase the duty ratio of the power supply device. Here, the control signal voltage Vc may include a switching operation signal and the like for increasing the duty ratio of the power supply device. 
     As such, when the output current Iout becomes greater than the reference current Iref during operation, the output of the comparator  64  becomes low, the diode  63  is turned on, and thus the control signal voltage Vc is lowered, and accordingly, the duty ratio of the power supply device is also reduced. As a result, it operates so that the output current Iout becomes equal to the reference current Iref, and a mode at this time is referred to as a constant current (CC) mode. 
     When the output current of the power supply device increases, the output voltage increases, and the output voltage Vout becomes greater than the reference voltage Vref, and the output of comparator  61  goes low, which causes diode  62  to turn on. Due to this, the voltage Vc is lowered, and accordingly, the duty ratio of the power supply device is also lowered. Eventually, it operates so that the output voltage Vout becomes equal to the reference voltage Vref, and a mode at this time is referred to as a constant voltage (CV) mode. 
     As shown in  FIG.  7   , when an output diode and a CC-CV circuit are used without a load share bus, parallel operation is possible, but load sharing is not performed. As the output voltage increases, for the same reason as in  FIG.  4   , the duty ratio of the power supply devices whose target voltage becomes lower than the output voltage decreases, so that the current of each power supply device is not maintained, and thereby occurring a current imbalance. 
     In  FIG.  8   , in which a battery is connected as a load, for the same reason, as the battery is charged, the duty ratio of the power supply devices in which the target voltage becomes lower than the output voltage decreases, and the current of each power supply device is not maintained, and thereby occurring a current imbalance. 
     In this way, load sharing is performed even when there is a deviation of the target voltage of the power supply devices, and a load sharing control device according to an embodiment of the present invention includes a first control unit  100  and a second control unit  200  so that load sharing can be performed even in CV mode. 
     The first control unit  100  generates a first control signal  104  controlling the output current  101  of the power supply device  300  using the output current  101  of the power supply device  300  and the current of the load share bus  400 . 
     More specifically, the first control unit  100  generates the first control signal  104  to follow the maximum current  103  among the output currents of a plurality of power supply devices receiving the output current  101  of the power supply device  300  from the load share bus  400 , for road sharing. Here, the first control signal  104  may be a control signal for controlling the second control unit  200  for controlling the output voltage of the power supply device  300 . According to the first control signal  104 , the output current  101  operates in the same manner as the maximum current  103 . At this time, when the output current  101  of the power supply device  300  is the maximum current among the output currents of the other power supply devices, the corresponding output current  101  is delivered to the other power supply device as the maximum current  103  of the load share bus  400 . 
     The first control unit  100  generates a first control signal  104  so that the output current  101  is equal to the maximum current  103  of the load share bus  400 , but the output current  101  is limited to the threshold current  102  or less. When there is no limit value of the output current  101 , the output current  101  continues to increase, which may affect the entire power supply system. Therefore, for power derating of the power supply, the output current  101  is limited to the threshold current  102  or less. Here, the threshold current  102  has a preset value, or it can be set using the reference current being used when the power supply device is constant current (CC) controlled. When setting the threshold current  102  using a reference current, the threshold current may be set by subtracting a predetermined value from the reference current. Here, the current value subtracted from the reference current may vary depending on the specifications of the power supply device or the degree of safety requirements. Or, the reference current may be set as the threshold current  102 . 
     The second control unit  200  generates a second control signal  203  for controlling the output voltage of the power supply device  300  by using a target voltage  201  of the power supply device  300 , a feedback voltage  202  being fed back from the output voltage of the power supply device  300 , and a control voltage according to the first control signal  104  of the first control unit  100 . 
     More specifically, the second control unit  200  performs control of the power system of the power supply device  300 , and generates a second control signal  203  for controlling the output voltage of the power supply device  300  by using the target voltage  201 , the feedback voltage  202 , and the first control signal  104 . The second control signal  203  for controlling the output voltage of the power supply device  300  is generated such that the voltage obtained by subtracting the control voltage according to the first control signal  104  from the feedback voltage  202  becomes the target voltage  201 . 
     Load sharing for each power supply device  300  is performed by using the first control signal  104  of the first control unit  100  for controlling the output current  101  to be equal to the maximum current  103 , and the second control signal  203  of the second control unit  200  for controlling the output voltage of the power supply device  300  so that the voltage obtained by subtracting the control voltage according to the first control signal  104  from the feedback voltage  202  becomes the target voltage  201 ; and the first control unit  100  performs power derating by limiting the output current  101  to the threshold current  102  or less. 
       FIG.  9    is a block diagram of a first control unit of a load sharing control device according to an embodiment of the present invention. 
     The first control unit  100  of the load sharing control device according to an embodiment of the present invention may comprise a first comparison unit  110 , a first calculation unit  130 , and a current control unit  140  as shown in  FIG.  9   , and may include a second comparison unit  120 . In generating the first control signal, currents are compared or calculated, and at this time, a sensing voltage, not a current, that measures current, may be used in comparing currents. That is, in comparing between the currents, a comparison may be performed between the sensing voltages sensing the respective currents. 
     The first comparison unit  110  compares the output current  101  and the current of the load share bus  400 . The first comparison unit  110  compares the output current  101  and the maximum current  103 , and determines which of the output current  101  and the maximum current  103  is larger. When the output current  101  is greater than the maximum current  103 , the maximum current of the load share bus  400  is changed to the output current  101 . 
     The first calculation unit  130  calculates the difference between the output current  101  and the current of the load share bus  400 . The first control unit  100  controls the output current  101  to be equal to the maximum current  103 , and the first calculation unit  130  calculates the difference between the output current  101  and the maximum current  103  in order to determine whether the output current  101  and the maximum current  103  are the same and at the same time generate a first control signal using the difference between the output current  101  and the maximum current  103 . 
     The current control unit  140  generates a first control signal according to the output of the first calculation unit  130 . That is, the first control signal is generated to reduce the corresponding difference according to the difference between the output current  101  and the maximum current  103  being outputted from the first calculation unit  130 . The current control unit  140  may generate the first control signal  104  for controlling the level of the feedback voltage  202  being inputted to the second control unit  200 . When the output current  101  is lower than the maximum current  103 , it is necessary to control to increase the output current  101 , and for this, the duty ratio of the power supply device  300  must be increased. That is, by lowering the feedback voltage of the output voltage being used by the second control unit  200  for controlling the duty ratio of the power supply device  300  to control the duty ratio than the actual feedback voltage, it is possible to prevent the second control unit  200  from lowering the duty ratio according to the actual feedback voltage. 
     The output current gradually increases according to the first control signal of the current control unit  140 , and in order to limit excessively high power supply, the first control unit  100  may include a second comparison unit  120  for limiting the output current to a threshold current. The second comparison unit  120  compares the output current  101  and the threshold current  102  so that a lower current is applied to the first comparison unit  110 . That is, when the output current  101  becomes greater than the threshold current  102 , the second comparison unit  120  outputs a threshold current  102  as an output, and the threshold current  102  is set to be greater than the maximum current  103 , and the threshold current  102  is outputted as an output of the first comparison unit  110 . Then, the output current  101  is controlled to be equal to the threshold current  102  by the first calculation unit  130  and the current control unit  140 , and the output current  101  is limited to the threshold current  102 . At this time, the threshold current may be set to a maximum current value to be controlled by load sharing. Or, it may be set to a current value for limiting the supply power. 
       FIG.  10    is a block diagram of a second control unit of a load sharing control device according to an embodiment of the present invention. 
     The second control unit  200  of the load sharing control device according to the embodiment of the present invention, as shown in  FIG.  10   , may comprise a second calculation unit  210 , a third calculation unit  220 , and a voltage control unit  230 . 
     The second calculation unit  210  calculates a difference between the feedback voltage  202  and the control voltage according to the first control signal  104 . As previously described, the first control signal  104  is a control signal for lowering or increasing the feedback voltage  202  of the output voltage, the difference between the feedback voltage  202  and the control voltage according to the first control signal  104  is calculated in order to lower or increase the feedback voltage  202  as much as the control voltage according to the first control signal  104 . 
     The third calculation unit  220  calculates the difference between the output of the target voltage  201  and the second calculation unit  210 . The voltage control unit  230  for controlling the duty ratio of the power supply device controls so that the output voltage becomes the target voltage  201 . To this end, the third calculation unit  220  calculates and outputs the difference between the output of the target voltage  201  and the second calculation unit  210 . 
     The voltage control unit  230  generates a second control signal  203  for controlling the output voltage of the power supply device so that the output voltage becomes the target voltage according to the output of the third calculation unit  220 . The second control signal  203  is a signal for controlling the power supply of the power supply device  300 . The voltage control unit  230  may include a pulse width modulator (PWM). In order to control the duty ratio for controlling the power supply of the power supply device  300 , it may include a pulse width modulator capable of controlling the duty ratio of the signal, thereby controlling the duty ratio of the power supply device. 
     When it is necessary to limit the supply power for each power supply device  300 , at least one of the target voltage  201  and the threshold current  102  may be adjusted. Since supply power is controlled by the output voltage and output current, the output voltage is limited to the target voltage  201 , and the output current is limited to the threshold current  102 , the supply power may be limited by adjusting at least one of the target voltage  201  and the threshold current  102 . That is, through this, power derating, which is a supply power limitation, is possible. 
     A load sharing control device according to an embodiment of the present invention may be implemented as shown in  FIG.  11   . 
     Comparison of output current, maximum current, and threshold current can be performed using the sensing voltage or set voltage of each current. The output current sensing voltage  1101  is compared with the maximum current sensing voltage of the load share bus  1400  through the comparator  1111  and the diode  1112  so that it can deliver the largest output current among the output currents of each power supply device. The difference between the output current sensing voltage  1101  and the sensing voltage  1400  of the maximum current is calculated ( 1130 ), and according to the corresponding difference, the current control unit  1140  generates a first control signal so that the sensing voltage  1101  of the output current becomes equal to the sensing voltage  1400  of the maximum current. At this time, the current control unit  1140  may perform control through PI control. As a result, the output current increases, and the output voltage sensing voltage  1101  increases accordingly, and comparison may be performed with the threshold current voltage  1102  and the diode  1120  in order to limit the magnitude of the output voltage sensing voltage  1101 . When the output current sensing voltage  1101  is greater than the threshold current voltage  1102 , the diode is turned on and the threshold current voltage  1102  is inputted to the positive (+) terminal input of the comparator  1111 , and since the threshold current voltage  1102  is greater than the sensing voltage  1400  of the maximum current, the output current sensing voltage  1101  is controlled to be equal to the threshold current voltage  1102  by the current control unit  1140 , so that the output current is limited to the threshold current. In this way, since the output current is limited to the threshold current to operate in the constant current mode, components that perform load sharing may be referred to as a load sharing controller (CC controller  1150 ). 
     The control voltage according to the control signal of the current control unit  1140  is used to control the feedback voltage of the output voltage  1202 . That is, the difference between the feedback voltage of the output voltage  1202  and the control voltage according to the control signal of the current control unit  1140  is calculated ( 1210 ), and the difference from the target voltage  1201  is calculated ( 1220 ) according to the result. The voltage control unit  1230  generates a second control signal so that the difference between the feedback voltage of the output voltage  1202  and the control voltage according to the control signal of the current control unit  1140  is equal to the target voltage  1201 . At this time, the voltage control unit  1230  may perform control through PI control. The control signal of the voltage control unit  1230  is applied to the pulse width modulator (PWM,  1240 ), so that it is possible to control the duty ratio of the signal being applied to a power stage  1300  of the power supply device. Since the voltage control unit  1230  and the pulse width modulator  1240  limit the voltage to the target voltage to operate in a constant voltage mode, it may be referred to as a CV controller  1250 . 
     The load sharing control device being implemented as shown in  FIG.  11    may operate as shown in  FIG.  12    when the load battery voltage is higher than the target voltage in a CC mode where the output current is stabilized to the maximum current, or when the battery voltage is controlled by another power supply device in a CV mode in which the output voltage is stabilized to the target voltage. For example, when the battery voltage is 12 V and the target voltage is 11 V, since the output current is in a stabilized state at the maximum current, the output from the calculation unit  1130  is 0, and the control voltage according to the control signal being outputted from the current control unit  1140  may be 1 V to lower the 12 V feedback voltage of the output voltage to the target voltage of 11 V. The duty ratio of the power supply device can be controlled so that 0 V is inputted as the difference between the target voltage being inputted to the voltage control unit  1230  and the feedback voltage of the output voltage. That is, 5 V is outputted, and the PWM outputs Vg=24 V, Vm=10 V, and duty ratio D=0.5, so that load sharing of power supply devices can be performed. 
     In the CC mode, when the battery voltage is lower than the target voltage, the operation may be performed as shown in  FIG.  13   . For example, when the battery voltage is 10 V and the target voltage is 11 V, the output current is stabilized at the maximum current, the output from the calculation unit  1130  is 0, and accordingly, the control voltage according to the control signal being outputted from the current control unit  1140  may be −1 V to increase the feedback voltage of 10 V according to the output voltage to the target voltage of 11 V. The duty ratio of the power supply device can be controlled so that 0 V is inputted as the difference between the target voltage being inputted to the voltage control unit  1230  and the feedback voltage of the output voltage. That is, 4.1 V is outputted, and the PWM outputs Vg=24 V, Vm=10 V, and duty ratio D=0.5, so that load sharing of the power supply device can be performed. 
     In the load sharing control circuit connected in parallel to the load and included in each of a plurality of power supply devices including a CV circuit or a CC-CV circuit, a load sharing control circuit according to an embodiment of the present invention may comprise: a maximum current output circuit unit for outputting the larger voltage among the output current sensing voltage sensing the output current of the power supply device and the voltage of the load share bus; a minimum current output circuit unit for outputting the smaller voltage among the output of the maximum current output circuit unit and a voltage according to a threshold current; and an amplification unit amplifying the difference between the output current sensing voltage and the output of the minimum current output circuit unit and applying it to a CV feedback terminal of the CV circuit or the CC-CV circuit. 
       FIG.  14    is a circuit diagram of a load sharing control circuit according to an embodiment of the present invention. 
     The load sharing control circuit  2150  according to an embodiment of the present invention is a circuit corresponding to the load sharing control device described with reference to  FIGS.  1  to  13   , and hereinafter, overlapping descriptions will be omitted. As described in  FIG.  13   , it is necessary to apply a negative (−) value as a control voltage to be subtracted from the feedback voltage of the output voltage in order to perform load sharing, and in order to implement this as an analog circuit, as shown in  FIG.  14   , a load sharing control circuit according to an embodiment of the present invention may be implemented. 
     The maximum current output circuit unit may comprise: a first comparator  2111  receiving the output current sensing voltage  1201  via the positive (+) input terminal, and receiving the voltage of the load share bus  2400  via the negative (−) input terminal; and a first diode  2112  to which the output end of the first comparator  2111  and the anode are connected, and the voltage of the load share bus  2400  and the cathode are connected. It may include a second amplifier  2103  sensing and amplifying the output current and outputting an output current sensing voltage  2101 . Precise sensing of the output current is possible by sensing and amplifying the output current  2102  by the second amplifier  2103 . Here, the second amplifier may be a high-precision OP-AMP. In addition, the first comparator  2111  may be implemented as an OP-AMP comparator or the like. The larger voltage of the voltages of the output current  2101  or the voltage of the load share bus  2400  is outputted as the voltage of the maximum current by the first comparator  2111  and the first diode  2112 . 
     Minimum current output circuit unit may include: a second comparator  2122  receiving the voltage according to the threshold current  2103  via the positive (+) input terminal, and receiving the output of the maximum current output circuit unit via the negative (−) input terminal; and a second diode  2121  to which the output terminal and the cathode of the second comparator  2122  are connected, and the voltage of the load share bus  2400  and the anode are connected. Here, the threshold current  2103  may be a preset value or a value (Iref−ΔI) obtained by subtracting a predetermined value ΔI from the reference current Iref of the CC-CV circuit. Since the cathode-anode direction of the second diode  2121  is opposite to the direction of the first diode  2112 , the smaller voltage among the voltage according to the threshold current  2103  and the output of the maximum current output circuit unit is outputted and applied to the amplification unit. That is, the positive (+) input of the transconductance amplifier  2131  comprising the amplification unit may be limited to the voltage of the threshold current. 
     The amplification unit may include: a transconductance amplifier  2131  for amplifying the difference between the output current  1201  sensing voltage and the output of the minimum current output circuit unit; a first amplifier  2133  for amplifying the output of the transconductance amplifier  2131 ; and a transistor  2134  whose base is connected with the output end of the first amplifier  2133 , emitter is connected with the negative (−) input terminal of the first amplifier, and collector is connected with the CV feedback terminal  2210 . The transconductance amplifier is an amplifier that multiplies the difference in voltage input by a gain and outputs it as a current, and amplifies the difference between the output current  1201  sensing voltage and the output of the minimum current output circuit unit, and outputs it. The transconductance amplifier  2131  may have a predetermined offset voltage  2132 . Through this, when the difference between the sensing voltage  1201  of the output current and the sensing voltage of the maximum current is equal to or greater than the offset voltage, the current control function can be operated. Through this, it is possible to prevent errors such as current control due to malfunction of the amplifier. Here, the offset voltage may be preset and may be set to 25 mV. The output of the transconductance amplifier  2131  is amplified in the first amplifier  2133 , and by applying a voltage to the resistor connected to the emitter of the transistor  2134 , the voltage of the CV feedback terminal  2210  being connected to the collector of the transistor  2134  is decreased or increased. That is, the voltage of the CV feedback terminal  2210  may be controlled to positive (+) or negative (−). Through this, even in a CV mode in which the output voltage  2202  becomes greater than the reference voltage  2201  which is the target voltage, the power supply device may be operated to enable load sharing. 
     As previously described, in the implemented load sharing control circuit, at least one among the reference voltage of the CC-CV circuit, the reference voltage of the CV circuit, or the threshold current can be adjusted depending on the power limit of the power supply device. For each power supply device  300 , if it is necessary to limit the supply power, at least one among the reference voltage of the CC-CV circuit, the reference voltage of the CV circuit corresponding to the target voltage, or the threshold current may be adjusted. Since the supply power is controlled by the output voltage and the output current, the output voltage is limited by the reference voltage, and the output current is limited by the threshold current, supply power may be limited by adjusting at least one of a reference voltage and a threshold current. That is, through this, power derating, which is a supply power limitation, is possible. 
     As shown in  FIG.  14   , a load sharing control circuit being implemented according to the embodiment of the present invention may operate in various operating modes. 
     In the case of stand-alone operation rather than parallel operation with other power supply devices, as shown in  FIG.  15   , the load sharing control circuit  2150  is equivalently opened, so that only the CC-CV circuit operates. 
     When driving in parallel with other power supply devices, when the output voltage is lower than the target voltage, as shown in  FIG.  16   , it is operated in a CC mode, and the CV circuit and the load sharing control circuit  2150  are equivalently opened. It is controlled to operate in a way that the output current  2202  is limited to the reference current  2102  by the CC circuit. 
     When driving in parallel with other power supply devices, and when the output voltage is higher than the target voltage, as shown in  FIG.  17   , while operating in a CV mode, the load sharing control circuit  2150  operates for load sharing. At this time, the CC circuit is equivalently opened. At this time, the load sharing is performed, but it is controlled to operate in a way that the output current is limited to the threshold current  2103 , not the reference current  2102 . 
     When the battery is connected to the load, as shown in  FIG.  14   , the load sharing control circuit  2150  is connected to the CC-CV circuit and operates, and when the battery is not connected to the load, as shown in  FIG.  18   , the load sharing control circuit  2150  may operate by being connected only to the CV-circuit, not the CC-CV circuit. That is, load sharing may be performed by being included in a power supply device applied to various applications and loads that supply power for a server, supply DC-DC power for a vehicle, or supply DC-DC power for a DC distribution system. Other than this, it is natural that various devices for supplying power may be included. 
     As described above, through a load sharing control device or control circuit capable of power derating, stand-alone operation is possible, a redundancy function is performed, and power derating is possible by adjusting the target voltage and threshold current. In addition, load sharing operation is possible in all sections of CC-CV even when the battery is connected to the load, and the CC control circuit is operated when the output is short-circuited so that the elements can be protected. 
     It is natural that each configuration of the load sharing control device according to an embodiment of the present invention may be implemented by software or hardware such as a circuit. 
     Although embodiments of the present invention have been described with reference to the accompanying drawings, those of ordinary skill in the art to which the present invention belongs will be able to understand that the present invention can be embodied in other specific forms without changing its technical spirit or essential features. Therefore, it should be understood that the embodiments described above are illustrative in all respects and not restrictive.