Patent Publication Number: US-10759292-B2

Title: Vehicle charging apparatus, current stabilization method thereof, and recording medium for recording program for implementing the method

Description:
CROSS-REFERENCE(S) TO RELATED APPLICATION(S) 
     The present application claims priority to Korea Application No. 10-2017-0121791, filed on Sep. 21, 2017, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The present invention relates to a vehicle charging apparatus, a current stabilization method thereof, and a recording medium in which a program for implementing the method is recorded. 
     Description of Related Art 
     Eco-friendly vehicles include a hybrid electric vehicle (HEV), a plug-in HEV, an electric vehicle, a fuel cell vehicle, and the like. Thereamong, the plug-in HEV and the electric vehicle may be charged using a household power source. To the present end, these two types of vehicles are provided with an on-board battery charger (OBC). 
       FIG. 1A  is a graph illustrating stable currents I 1  and I 2  and a stable voltage V 1 , and  FIG. 1B  illustrates unstable currents I 3 , I 4 , and I 5  and an unstable voltage V 2 . In each graph, the horizontal axis denotes elapsed time and the vertical axis denotes a level. 
     The OBC is a device configured for receiving electrical energy (e.g., an alternating current (AC) power source) from electric vehicle supply equipment (EVSE) of the electric vehicle and then charging a high-voltage battery through an in-cable control box (ICCB). 
     Since the OBC utilizes an AC power source, the OBS is significantly affected by a system environment and equipment. An AC current and voltage supplied to the OBC by a system impedance of a country and a specific region may not be stable, as opposed to  FIG. 1A , and may be unstable as illustrated in  FIG. 1B . The AC current and voltage may become unstable in an abnormal charging environment, for example, poor connection of a charging connector, damage of an AC input power source system, an instantaneous shutdown situation including an accident, or a charging environment in an area where stability of the AC input power source system is somewhat low. When an AC input power source is instantaneously shut down, instantaneous shutdown of EVSE of the AC input power source during recharging of a battery by the OBC may generate at least one of overcurrent or overvoltage in an internal of a circuit of a power factor corrector (PFC) disposed within the OBC, damaging the OBC or deteriorating charging efficiency of the OBC. 
     To solve the provided problem, a method of changing an input filter disposed within the OBC has been provided. However, the provided method causes increase in manufacturing costs and reduction in efficiency. 
     The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgment or any form of suggestion that this information forms the prior art already known to a person skilled in the art. 
     BRIEF SUMMARY 
     Various aspects of the present invention are directed to providing a vehicle charging apparatus, a current stabilization method thereof, and a recoding medium in which a program for implementing the method is recorded, that substantially obviates one or more problems due to limitations and disadvantages of the related art. 
     An aspect of various exemplary embodiments are directed to providing a vehicle charging apparatus having stable current control performance, a current stabilization method thereof, and a recoding medium in which a program for implementing the method is recorded. 
     In an exemplary embodiment of the present invention, a current stabilization method performed by a vehicle charging apparatus, which may include a power factor corrector for correcting a power factor of an alternating current (AC) power source, the vehicle charging apparatus converting an AC voltage of the AC power source into a direct current (DC) voltage to charge a vehicle battery, may include downwardly-adjusting a current control bandwidth of the power factor corrector when the current control bandwidth of the power factor corrector needs to be adjusted. 
     For example, the current stabilization method may further include determining whether the current control bandwidth of the power factor corrector needs to be adjusted, and operating the power factor corrector using the downwardly-adjusted current control bandwidth. 
     For example, the determining may include determining whether overcurrent has occurred in the power factor corrector, determining a number of occurrences of overcurrent, and determining whether the determined number of occurrences of overcurrent is equal to or greater than a first predetermined number of occurrences, wherein, when the determined number of occurrences of overcurrent is equal to or greater than the first predetermined number of occurrences, the current control bandwidth may be downwardly-adjusted. 
     For example, the determining of whether the current control bandwidth of the power factor corrector needs to be adjusted may further include determining whether the determined number of occurrences of overcurrent is equal to or greater than a second predetermined number of occurrences when the determined number of occurrences of overcurrent is equal to or greater than the first predetermined number of occurrences, the current control bandwidth being downwardly-adjusted when the determined number of occurrences of overcurrent is less than the second predetermined number of occurrences, and wherein the second predetermined number of occurrences may be greater than the first predetermined number of occurrences. 
     For example, the current stabilization method may further include stopping an operation of the power factor corrector and initializing the current control bandwidth, when the determined number of occurrences of overcurrent is equal to or greater than the second predetermined number of occurrences. 
     For example, the current stabilization method may further include determining whether charging of the vehicle battery is complete, and stopping an operation of the power factor corrector and initializing the current control bandwidth when charging of the battery is completed. 
     For example, the downwardly-adjusting the current control bandwidth may include downwardly-adjusting the current control bandwidth using the determined number of occurrences of overcurrent as follows:
 
 ABW=IBW −( C 1− X+ 1)·α
 
     wherein ABW denotes the downwardly-adjusted current control bandwidth, IBW denotes an initial current control bandwidth, C1 denotes the determined number of occurrences of overcurrent, X denotes the first predetermined number of occurrences, and α denotes the amount of downward adjustment of the current control bandwidth. 
     For example, the determining of whether the current control bandwidth of the power factor corrector needs to be adjusted may further include determine a duration in which overcurrent does not occur after overcurrent has occurred, and reducing the determined number of occurrences of overcurrent when the duration is equal to or greater than a predetermined duration. 
     For example, the downwardly-adjusting the current control bandwidth may include downwardly-adjusting the current control bandwidth using the determined number of occurrences of overcurrent as follows, when the determined number of occurrences of overcurrent is reduced:
 
 ABW=IBW −( CM−X+ 1)·α
 
     wherein ABW denotes the downwardly-adjusted current control bandwidth, IBW denotes an initial current control bandwidth, CM denotes a maximum value of the determined number of occurrences of overcurrent, X denotes the first predetermined number of occurrences, and a is the amount of downwardly-adjustment of the current control bandwidth. 
     For example, the operating the power factor corrector may include determining whether a current control bandwidth of the power factor corrector at a timing when overcurrent occurs is less than the downwardly-adjusted current control bandwidth, operating the power factor corrector in the current control bandwidth of a present timing when the current control bandwidth of the present timing is less than the downwardly-adjusted current control bandwidth, the current control bandwidth of the present timing corresponding to the current control bandwidth of the power factor corrector at a timing when the overcurrent occurs, and operating the power factor corrector in the downwardly-adjusted current control bandwidth when the downwardly-adjusted current control bandwidth is equal to or less than the current control bandwidth of the present timing. 
     For example, α may be 10 Hz to 2000 Hz. 
     In another exemplary embodiment of the present invention, a vehicle charging apparatus configured for converting an alternating current (AC) voltage of an AC power source into a direct current (DC) voltage and charging a vehicle battery may include an input filter configured to filter the AC voltage supplied from the AC power source and output the filtered result, a rectifier configured to rectify the filtered result and output the rectified result as a first DC voltage, a power factor corrector configured to correct a power factor of the charging apparatus using the first DC voltage in response to a first control signal and output the power factor corrected result as a second DC voltage, a level converter configured to convert a level of the second DC voltage in response to a second control signal and output the level-converted DC voltage to the battery, and a controller configured to determine whether a current control bandwidth of the power factor corrector needs to be adjusted, downwardly-adjust the current control bandwidth of the power factor corrector in response to the determined result, generate the first control signal corresponding to the downwardly-adjusted current control bandwidth, and generate the second control signal to control the level converter. 
     For example, the controller may include a first controller configured to generate the first control signal and a second controller configured to generate the second control signal. 
     For example, the first controller may include an adjustment determiner configured to determine whether the current control bandwidth of the power factor corrector needs to be adjusted, a bandwidth adjuster configured to downwardly-adjust the current control bandwidth of the power factor corrector in response to a determined result, and an operation controller configured to generate the first control signal corresponding to the downwardly-adjusted current control bandwidth. 
     For example, the adjustment determiner may include a detector configured to detect whether overcurrent has occurred in the power factor corrector, a number-of-occurrences counter configured to determine the number of occurrences of overcurrent according to a detected result in the detector, and a first comparator configured to compare the number of occurrences of overcurrent determined in the number-of-occurrences counter with a first predetermined number of occurrences, wherein the bandwidth adjuster may downwardly-adjust the current control bandwidth in response to the compared result in the first comparator. 
     For example, the adjustment determiner may further include a second comparator configured to compare the determined number of occurrences of overcurrent in the number-of-occurrences counter with a second predetermined number of occurrences in response to the compared result in the first comparator, wherein the second predetermined number of occurrences may be greater than the first predetermined number of occurrences, wherein the bandwidth adjuster may downwardly-adjust the current control bandwidth in response to the compared results in the first and second comparators, and wherein the operation controller may be configured to generate the first control signal in response to the compared result in the second comparator. 
     For example, the adjustment determiner may further include a duration counter configured to count a duration in which overcurrent does not occur after overcurrent has occurred through the detected result in the detector, and a third comparator configured to compare the duration counted in the duration counter with a predetermined duration, and wherein the number-of-occurrences counter may reduce the determined number of occurrences of overcurrent in response to the compared result in the third comparator. 
     For example, the bandwidth adjuster may downwardly-adjust the current control bandwidth using one of the following two equations in response to the compared results in the first to third comparators:
 
 ABW=IBW −( C 1− X+ 1)·α
 
or
 
 ABW=IBW −( CM−X+ 1)·α
 
     wherein ABW denotes the downwardly-adjusted current control bandwidth, IBW denotes an initial current control bandwidth, C1 denotes the determined number of occurrences of overcurrent in the number-of-occurrences counter, CM denotes a maximum value of the determined number of occurrences of overcurrent in the number-of-occurrence counter, X denotes the first predetermined number of occurrences, and α denotes the amount of downward adjustment of the current control bandwidth. 
     In various exemplary embodiments, a computer-readable recording medium records a program for implementing a current stabilization method performed by a vehicle charging apparatus, which may include a power factor corrector for correcting a power factor of an alternating current (AC) power source, the vehicle charging apparatus converting an AC voltage of the AC power source into a direct current (DC) voltage to charge a vehicle battery, wherein the program implements a function of downwardly-adjusting a current control bandwidth of the power factor corrector when the current control bandwidth of the power factor corrector needs to be adjusted. 
     The program may further implement a function of determining whether the current control bandwidth of the power factor corrector needs to be adjusted, and a function of operating the power factor corrector using the downwardly-adjusted current control bandwidth. 
     The methods and apparatus of the present invention have other features and advantages which will be apparent from or are set forth in more detail in the accompanying drawings, which are incorporated herein, and the following Detailed Description, which together serve to explain certain principles of the present invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1A  is a graph illustrating stable currents and a stable voltage; 
         FIG. 1B  is a graph illustrating unstable currents and an unstable voltage; 
         FIG. 2  is a block diagram of a vehicle charging apparatus according to an exemplary embodiment of the present invention; 
         FIG. 3  is a block diagram partially illustrating the charging apparatus of  FIG. 2 ; 
         FIG. 4  is a flowchart for explaining a current stabilization method according to an exemplary embodiment of the present invention; 
         FIG. 5  is a block diagram of a first controller according to an exemplary embodiment for performing the current stabilization method of  FIG. 4 ; 
         FIG. 6  is a flowchart for explaining an exemplary embodiment of steps  210 - 1  and  210 - 2  as illustrated in  FIG. 4 ; 
         FIG. 7  is a block diagram of an exemplary embodiment of an adjustment determiner as illustrated in  FIG. 5 ; 
         FIG. 8  is a flowchart for explaining another exemplary embodiment of step  210 - 1  as illustrated in  FIG. 4 ; 
         FIG. 9  is a flowchart for explaining an exemplary embodiment of step  230  as illustrated in  FIG. 4 ; and 
         FIG. 10A  and  FIG. 10B  are graphs for explaining operations of the charging apparatus according to a comparative example and an exemplary embodiment of the present invention, respectively. 
     
    
    
     It should be understood that the appended drawings are not necessarily to scale, presenting a somewhat simplified representation of various features illustrative of the basic principles of the invention. The specific design features of the present invention as disclosed herein, including, for example, specific dimensions, orientations, locations, and shapes will be determined in part by the particularly intended application and use environment. 
     In the figures, reference numbers refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present invention(s), examples of which are illustrated in the accompanying drawings and described below. While the invention(s) will be described in conjunction with exemplary embodiments, it will be understood that the present description is not intended to limit the invention(s) to those exemplary embodiments. On the contrary, the invention(s) is/are intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the invention as defined in the appended claims. 
     Furthermore, as used herein, relational terms, including “first”, “second”, “on”/“upper”/“above”, “under”/“lower”/“below,” and the like, are used solely to distinguish one entity or element from another entity or element without necessarily requiring or implying any physical or logical relationship or order between such entities or elements. 
     Hereinafter, a construction and operation of a vehicle charging apparatus  100  according to an exemplary embodiment will be described with reference to the accompanying drawings. 
       FIG. 2  is a block diagram of the vehicle charging apparatus  100  according to an exemplary embodiment. 
     The vehicle charging apparatus  100  is connected between an AC power source  10  and a vehicle battery  20  and converts an AC voltage supplied from the AC power source  10  into a direct current (DC) voltage to charge the battery  20 . The charging apparatus  100  of  FIG. 2  may be a type of an on-board battery charger (OBC) but the present invention and exemplary embodiments are not limited thereto. The battery  20  is configured to provide driving power to a vehicle. 
     Herein, the AC power source  10  may be an external power source to a vehicle, for example, a household power source. 
     The vehicle charging apparatus  100  may include an input filter  110 , a rectifier  120 , a power factor corrector (PFC)  130 , a level converter  140 , and a controller  150 . 
     The input filter  110  filters the AC voltage supplied from the AC power source  10  and outputs the filtered result to the rectifier  120 . Since the input filter  110  filters the AC voltage, conductive noise and radiative noise included in the AC voltage may be cancelled or reduced. 
     A converter, which converts AC power into DC power through switching, may include the input filter  110  as illustrated in  FIG. 2 . Although the input filter  110  is disposed at an input side of the charging apparatus  100  in  FIG. 2 , the present invention is not limited thereto. That is, according to various exemplary embodiments, the input filter  110  may be disposed at an output side of the charging apparatus  100 . 
     The input filter  110  may be an electromagnetic interference (EMI) filter and may be implemented by at least one of an inductor or a capacitor. 
     The rectifier  120  rectifies a result filtered by the input filter  110  and outputs the rectified result to the PFC  130  as a first DC voltage. The rectifier  120  may be implemented by a circuit including diodes, for example, a full-wave rectification circuit including full-bridge diodes. 
     The PFC  130  is configured to correct a power factor of a power source. In more detail, the PFC  130  is configured to reduce power loss in a process of converting AC power into DC power. Accordingly, a power factor of an input voltage/current of the charging apparatus  100  may be corrected by the PFC  130 . For example, the PFC  130  may increase transmission efficiency by eliminating a difference in phase between a voltage and a current of the AC power source, using an internal matching circuit. 
     The PFC  130  may perform or stop the above-described operation in response to a first control signal output from the controller  150 . The PFC  130  corrects the power factor of the charging apparatus  100  using the first DC voltage output from the rectifier  120  and outputs the power factor corrected result to the level converter  140  as a second DC voltage. 
     The level converter  140  is connected between an output terminal of the PFC  130  and an input terminal of the battery  20 . The level converter  140  converts the level of the second DC voltage in response to a second control signal output from the controller  150  and outputs the level-converted voltage to the battery  20 . That is, the level converter  140  may boost or buck the second DC voltage output from the PFC  130  into a third DC voltage for charging the battery  20 . For example, the level converter  140  may be implemented by an insulated DC-DC converter which adopts a switching circuit of a full-bridge or half-bridge type, however, the present invention is not limited thereto. 
     The controller  150  is configured to control the PFC  130  and the level converter  140 . To the present end, the controller  150  may include first and second controllers  152  and  154 . The first controller  152  is configured to generate the first control signal and transmit the first control signal to the PFC  130 , and the second controller  154  is configured to generate the second control signal and transmit the second control signal to the level converter  140 . 
     For example, when each of the PFC  130  and the level converter  140  is implemented by a pulse width modulation (PWM) driving circuit to perform the aforementioned functions, the first and second control signals may be gate signals of a PWM scheme. The PFC  130  may perform or stop an operation in response to the first control signal. For example, the operation of the PFC  130  may be stopped by cutting off a current or a voltage supplied to the PFC  130  by the first control signal. Similarly, the level converter  140  may perform or stop the operation in response to the second control signal. 
     Meanwhile, in controlling current, the above-described charging apparatus  100  may become unstable due to the input filter  110 . Among converters, an OBC charges the battery  20  using an external power source system, and thus the charging apparatus  100  may be affected by various factors including an environment and a region. For example, control of the charging apparatus  100  may become unstable due to system impedance, which may cause customer complaints regarding an inability to charge. For example, causes of unstable control of the charging apparatus  100  may include an environmental factor including an input voltage/current, internal elements of the input filter  110 , and a control transfer function. 
     Prior to a description of a current stabilization method for stably controlling an unstable current according to an exemplary embodiment of the present invention, a theoretical background will now be explained below. 
       FIG. 3  is a block diagram partially illustrating the charging apparatus  100  of  FIG. 2 . 
     An AC power source  10 , an input filter  110 , and a rectifier  120  illustrated in  FIG. 3  respectively correspond to the AC power source  10 , the input filter  110 , and rectifier  120  illustrated in  FIG. 2 . Therefore, the same reference numerals are used and a repetitive description is omitted. In  FIG. 3 , L 1  corresponds to a first load between the AC power source  10  and the input filter  110  and L 2  corresponds to a second load of constituent elements disposed subsequent the rectifier  120  output. 
     An output impedance Z OF  of the input filter  110  shown in  FIG. 3  may increase by the first load L 1 . Herein, when the output impedance Z OF  of the input filter  110  is greater than an input impedance Z IC  of the charging apparatus  100 , current control may become unstable. 
     An input admittance Y IC  of the charging apparatus  100  is a reciprocal of the input impedance Z IC  of the charging apparatus  100  and may be expressed as Equation 1. 
     
       
         
           
             
               
                 
                   
                     
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                               sL 
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     Herein, I bs_ref  denotes a root mean square (RMS) of an AC current supplied from the AC power source  10 , V ACRMS  denotes an RMS of an AC voltage supplied from the AC power source  10 , L denotes an inductance of the PFC  130 , and G ci  denotes a current control transfer function of the PFC  130 . 
     In Equation 1, I bs_ref /V ACRMS  is a fixed value and is invariable, whereas L and G ci  may be variable. 
     To stabilize current control of the charging apparatus  100 , the output impedance Z OF  of the input filter  110  needs to be decreased and the input impedance Z IC  of the charging apparatus  100  needs to be increased. That is, it is necessary to decrease the input admittance Y IC  of the charging apparatus  100  indicated in the above Equation 1. 
     First, to decrease the output impedance Z OF , a circuit configuration of the input filter  110  may be modified. That is, an X-capacitance and inductance of the input filter  110  may be modified and a damping resistor may be added. 
     Furthermore, to increase the input impedance Z IC  of the charging apparatus  100 , i.e., to decrease the input admittance Y IC  of the charging apparatus  100 , the inductance of the PFC  130  needs to be increased or a current control bandwidth (or response performance) in the current control transfer function G ci  needs to be lowered. 
     Hereinafter, a current stabilization method  200  according to an exemplary embodiment of the present invention, for stabilizing current of the charging apparatus  100  by the first controller  152  of the controller  150  illustrated in  FIG. 2 , will be described with reference to  FIG. 4 ,  FIG. 6 ,  FIG. 8 , and  FIG. 9 . While the current stabilization method  200  illustrated in  FIG. 4 ,  FIG. 6 ,  FIG. 8 , and  FIG. 9  is referred to as being performed by the first controller  152  illustrated in  FIG. 5  and  FIG. 7 , the present invention is not limited thereto. In other words, the current stabilization method  200  according to an exemplary embodiment of the present invention may also be performed by the first controller  152  having a configuration different from configurations illustrated in  FIG. 5  and  FIG. 7 . Alternatively, the current stabilization method  200  illustrated in  FIG. 4 ,  FIG. 6 ,  FIG. 8 , and  FIG. 9  may be performed through a program by the first controller  152 . 
       FIG. 4  is a flowchart for explaining the current stabilization method  200  according to an exemplary embodiment. 
       FIG. 5  is a block diagram of a first controller  152 A according to an exemplary embodiment for performing the current stabilization method  200  of  FIG. 4 . The first controller  152 A may include an adjustment determiner  160 , a bandwidth adjuster  170 , and an operation controller  180 . 
     The first controller  152 A of  FIG. 5  corresponds to an exemplary embodiment of the first controller  152  illustrated in  FIG. 2  and performs the same role as the first controller  152 . In more detail, the first controller  152 A is configured to determine whether a current control bandwidth of the PFC  130  needs to be adjusted. The first controller  152 A is configured to downwardly-adjust the current control bandwidth of the PFC  130  in response to the determined result, generates a first control signal corresponding to the downwardly-adjusted current control bandwidth, and outputs the first control signal to the PFC  130  (steps  210 - 1  and  210 - 2  to  250 ). The operation of the first controller  152 A will now be described more specifically with reference to  FIG. 4  and  FIG. 5 . 
     The adjustment determiner  160  determines whether the current control bandwidth of the PFC  130  needs to be adjusted ( 210 - 1 ). When it is determined that the current control bandwidth of the PFC  130  need not to be adjusted, the adjustment determiner  160  determines whether a fault of the PFC  130  is irreparable ( 210 - 2 ). Herein, a case in which the current control bandwidth of the PFC  130  needs not to be adjusted may be the case in which it is too early to adjust the current control bandwidth of the PFC  130  or a case in which the fault of the PFC  130  is irreparable. Accordingly, the adjustment determiner  160  performs step  210 - 2  to determine which case corresponds to the case in which adjustment of the current control bandwidth is not needed. 
     Hereinafter, an exemplary embodiment  210 A of steps  210 - 1  and  210 - 2  and an exemplary embodiment  160 A of the adjustment determiner  160  will be described. 
       FIG. 6  is a flowchart for explaining the exemplary embodiment  210 A of steps  210 - 1  and  210 - 2  illustrated in  FIG. 4 . 
       FIG. 7  is a block diagram of the exemplary embodiment  160 A of the adjustment determiner  160  illustrated in  FIG. 5 . The adjustment determiner  160 A may include a detector  161 , a number-of-occurrences counter  163 , a first comparator  165 , and a second comparator  167 . 
     The first controller  152  is configured to verify fault information related to the PFC  130  ( 211 ). The fault information related to the PFC  130  may be diverse. When the fault information includes only information as to whether or not overcurrent (or overvoltage) has occurred from the PFC  130 , step  211  may be omitted. For example, when a voltage including a spike is instantaneously generated from the AC power source  10 , since an AC voltage is higher than a DC link voltage, overcurrent may occur. However, the present invention is not limited to a specific situation in which overcurrent occurs. 
     After step  211 , the detector  161  detects whether overcurrent has occurred from the PFC  130  and outputs the detected result to the number-of-occurrences counter  163  and a duration counter  169  ( 213 ). 
     As illustrated in  FIG. 7 , the detector  161  may be included in each of the first controllers  152  and  152 A but the present invention is not limited thereto. According to various exemplary embodiments, the detector  161  may not be included in each of the first controllers  152  and  152 A and may be included in the PFC  130 . 
     After step  213 , the number-of-occurrences counter  163  determines the number of occurrences of overcurrent in the PFC  130  using the result detected by the detector  161  and outputs the determined result to the first and second comparators  165  and  167 . The number-of-times counter  163  also outputs the determined result to the bandwidth adjuster  170  through an output terminal OUT 4  ( 215 ). 
     After step  215 , the first comparator  165  compares the determined number in the number-of-occurrences counter  163  with a first number of occurrences X and outputs the compared result to the bandwidth adjuster  170  through an output terminal OUT 2  ( 217 ). That is, the first comparator  165  performs a comparison operation to determine whether the determined number in the number-of-occurrences counter  163  is equal to or greater than the first number of occurrences X. When it is detected that the determined number in the number-of-occurrences counter  163  is not equal to or greater than the first number of occurrences X as the result of comparison in the first comparator  165 , the detector  161  of the adjustment determiner  160  continues to perform step  211  and the bandwidth adjuster  170  does not perform step  220 . 
     Step  220  is not performed immediately upon occurrence of overcurrent in PFC  130 , and step  217  is performed to perform step  220  only when the number of occurrences of overcurrent reaches the first number of occurrences X. Since step  217  is performed in the above manner, unnecessary downwardly-adjustment of the current control bandwidth may be avoided. 
     The second comparator  167  compares the compared result in the number-of-occurrences counter  163  with a second number of occurrences Y in response to the compared result in the first comparator  165  and outputs the compared result to the bandwidth adjuster  170  through an output terminal OUT 3  ( 219 ). That is, the second comparator  167  performs a comparison operation to determine whether the determined number in the number-of-occurrences counter  163  is equal to or greater than the second number of occurrences Y. In the present case, the second comparator  167  may perform step  219  only upon determining that the determined number in the number-of-occurrences counter  163  is equal to or greater than the first number of occurrences X through the compared result in the first comparator  165 . 
     The second number of occurrences Y may be greater than the first number of occurrences X. When the current control bandwidth continues to be lowered, since a power factor and a threshold of a voltage output to the battery  20  from the charging apparatus  100  may be lowered, the first number of occurrences X and the second number of occurrences Y may be determined in consideration of the power factor and the threshold. For example, the first number of occurrences X may be 1 to 5, desirably 3, and the second number of occurrences Y may be 5 to 20, desirably, 10, but the present invention is not limited thereto. 
     Referring back to  FIG. 4  and  FIG. 5 , upon recognizing that the current control bandwidth of the PFC  130  needs to be adjusted in response to the determined result in the adjustment determiner  160 , the bandwidth adjuster  170  downwardly-adjusts the current control bandwidth of the PFC  130  and outputs the adjusted result to the operation controller  180  ( 220 ). 
     In other words, upon recognizing that the determined result in the number-of-occurrences counter  163  is less than the second number of occurrences Y through the compared result in the second comparator  167  after recognizing that the determined result in the number-of-occurrences counter  163  is equal to or greater than the first number of occurrences X through the compared result in the first comparator  165 , the bandwidth adjuster  170  may downwardly-adjust the current control bandwidth using the result output through the output terminal OUT 4  from the number-of-occurrences counter  163 . 
     In the present way, the bandwidth adjuster  170  may downwardly-adjust the current control bandwidth in response to the compared results in the first and second comparators  165  and  167 . 
     For example, the bandwidth adjuster  170  may downwardly-adjust the current control bandwidth using the determined number which is counted by the number-of-occurrences counter  163  and is output through the output terminal OUT 4 , as indicated by Equation 2.
 
 ABW=IBW −( C 1− X+ 1)·α  [Equation 2]
 
     Herein, ABW denotes a downwardly-adjusted current control bandwidth, IBW denotes an initial current control bandwidth, C1 denotes the determines number in the number-of-occurrences counter  163 , X denotes the first number of occurrences, and α denotes the amount of downward adjustment of the current control bandwidth. For example, when IBW is 2.2 kHz, C1 is 5, X is 3, and α is 100 Hz, then ABW may be 1.9 kHz. That is, the current control bandwidth may be downwardly-adjusted from 2.2 kHz to 1.9 kHz. 
       FIG. 8  is a flowchart for explaining another exemplary embodiment  210 B of step  210 - 1  as illustrated in  FIG. 4 . 
     To perform the method  210 B of  FIG. 8 , the adjustment determiner  160 A of  FIG. 7  may further include a third comparator  168  and a duration counter  169 . 
     The duration counter  169  of the adjustment determiner  160 A of  FIG. 7  counts a duration in which overcurrent does not occur after overcurrent has occurred through the detected result in the detector  161  and outputs the counted result to the third comparator  168   212 ). 
     The third comparator  168  compares the counted duration in the duration counter  169  with a predetermined duration Z and outputs the compared result to the number-of-occurrences counter  163  and to the bandwidth adjuster  170  through an output terminal OUT 5  ( 214 ). That is, the third comparator  168  performs a comparison operation to determine whether a duration in which overcurrent does not occur after overcurrent has occurred is equal to or greater than the predetermined duration Z. For example, the predetermined duration Z may be a few seconds to a few minutes, desirably, 30 seconds, but the present invention is not limited thereto. 
     Upon detecting that the duration in which overcurrent does not occur after overcurrent has occurred, the PFC  130  is equal to or greater than the predetermined duration Z through the compared result in the third comparator  168  and the number-of-occurrences counter  163  decreases the number of occurrences of overcurrent ( 215 ). When the number of occurrences of overcurrent is decreased, the current control bandwidth is increased again and then overcurrent may reoccur. 
     The exemplary embodiment  210 B of  FIG. 8  may be performed after step  215  and before step  217  as illustrated in  FIG. 6 . 
     When the adjustment determiner  160  does not perform the method of  FIG. 8 , the duration counter  169  and the third comparator  168  as illustrated in  FIG. 7  are omitted, and the current control bandwidth is adjusted as indicated in Equation 2, described above. 
     However, when the adjustment determiner  160  performs the method of  FIG. 8 , the bandwidth adjuster  170  may downwardly-adjust the current control bandwidth in response to the compared result output from the third comparator  168  through the output terminal OUT 5 . That is, upon recognizing that the duration in which overcurrent does not occur after overcurrent has occurred in the PFC  130  is equal to or greater than the predetermined duration Z through the compared result in the third comparator  168  and it is recognized that the determined number in the number-of-occurrences counter  163  is greater than the first number of occurrences X and less than the second number of occurrences Y through the compared results in the first and second comparators  165  and  167 , the bandwidth adjuster  170  may downwardly-adjust the current control bandwidth as indicated by Equation 3 using the determined number output from the number-of-occurrences counter  163  through the output terminal OUT 4 .
 
 ABW=IBW −( CM−X+ 1)·α  [Equation 3]
 
     Herein, CM denotes a maximum value of the determined number in the number-of-occurrences counter  163 . 
     As described above, the bandwidth adjuster  170  downwardly-adjusts the current control bandwidth as indicated by Equation 2 or 3 in response to the compared results in the first to third comparators  165 ,  167 , and  168 . For example, when IBW is 2.2 kHz, CM is 6, X is 3, and α is 100 Hz, then ABW may be 1.8 kHz. That is, the current control bandwidth may be downwardly-adjusted from 2.2 kHz to 1.8 kHz. 
     Even when the number of occurrences determined by the number-of-occurrences counter  163  is reduced in a same charging cycle, the current control bandwidth is downwardly-adjusted using CM instead of C1, as indicated by Equation 3. 
     Referring again to  FIG. 4  and  FIG. 5 , after step  220 , the operation controller  180  is configured to generate the first control signal corresponding to the current control bandwidth downwardly-adjusted by the bandwidth adjuster  170  and outputs the generated first control signal to the PFC  130  ( 230 ). Therefore, the PFC  130  may operate in the downwardly-adjusted current control bandwidth in response to the first control signal. 
     In the present case, the operation controller  180  is configured to generate the first control signal in response to the compared result in the second comparator  167 . That is, upon recognizing that the determined result in the number-of-occurrences counter  163  is less than the second number of occurrences Y through the compared result in the second comparator  167 , the operation controller  180  generates the first control signal in correspondence to the current control bandwidth downwardly-adjusted by the bandwidth adjuster  170 . However, upon recognizing that the determined result in the number-of-occurrences counter  163  is equal to or greater than the second number of occurrences Y through the compared result in the second comparator  167 , the operation controller  180  stops the operation of the PFC  130  using the first control signal. 
       FIG. 9  is a flowchart for explaining an exemplary embodiment  230 A of step  230  illustrated in  FIG. 4 . 
     Referring to  FIG. 9 , the operation controller  180  is configured to determine whether a current control bandwidth (hereinafter, referred to as a current control bandwidth of a present timing) of the PFC  130  at a timing when overcurrent occurs is less than a current control bandwidth downwardly-adjusted by the bandwidth adjuster  170  ( 232 ). 
     When the current control bandwidth of the present timing is less than the downwardly-adjusted current control bandwidth, the operation controller  180  is configured to generate the first control signal for operating the PFC  130  in the current control bandwidth of the present timing and outputs the first control signal to the PFC  130  through the output terminal OUT 1  ( 234 ). 
     However, when the downwardly-adjusted current control bandwidth is equal to or less than the current control bandwidth of the present timing, the operation controller  180  is configured to generate the first control signal for operating the PFC  130  in the current control bandwidth downwardly-adjusted by the bandwidth adjuster  170  and outputs the first control signal to the PFC  130  through the output terminal OUT 1  ( 236 ). 
     Furthermore, upon recognizing that the determined number in the number-of-occurrence counter  163  is equal to or greater than the second number of occurrences Y through the compared result in the second comparator  167  of the adjustment determiner  160 , the operation controller  180  may be configured to generate the first control signal for stopping the operation of the PFC  130  and outputs the first control signal to the PFC  130  through the output terminal OUT 1  ( 250 ). In the present case, the first controller  152  may be configured to initialize the current control bandwidth ( 250 ). The reason for initializing the current control bandwidth is that control performance may be secured when an operation of recharging the battery  20  is resumed after the charging apparatus  100  stops a charging operation. 
     That is, although the PFC  130  is operated in the downwardly-adjusted current control bandwidth in step  220  when the number of occurrences of overcurrent in the PFC  130  is equal to or greater than the first number of occurrences X but is less than the second number of occurrences Y, when the number of occurrences of overcurrent in the PFC  130  reaches the second number of occurrences Y, the first controller  152  is configured to stop the operation of the PFC  130 . When the operation of the PFC  130  is stopped, an operation of charging the battery  20  by the charging apparatus  100  is stopped. In the present case, the charging apparatus  100  according to an exemplary embodiment of the present invention may further include an alert device configured for alerting a user to necessity of hardware check. 
     Even when the number of occurrences of overcurrent in the PFC  130  is less than the second number of occurrences Y, when the downwardly-adjusted current control bandwidth in step  220  reaches a minimum value, the first controller  152  may be configured to stop the operation of the PFC  30 . How fast the downwardly-adjusted current control bandwidth reaches the minimum value may be determined by adjusting the amount of downward adjustment a of the current control bandwidth. For example, a may be 10 Hz to 2000 Hz, desirably, 100 Hz, but the present invention is not limited thereto. 
     Referring back to  FIG. 2  and  FIG. 4 , the first controller  152  may be configured to determine whether charging of the vehicle battery  20  is completed ( 240 ). To the present end, the first controller  152  is connected to the battery  20  and configured to determine whether the battery  20  has been charged. 
     When it is determined that charging of the battery  20  is not completed, the first controller  152  may be configured to continue to perform steps  210 - 1 ,  210 - 2 ,  220 , and  230  as illustrated in  FIG. 4 . However, when it is recognized that the charging of the vehicle battery  20  is completed, the first controller  152  may be configured to generate the first control signal for stopping the operation of the PFC  130  to output the first control signal to the PFC  130  and initialize the current control bandwidth ( 250 ). 
       FIG. 10A  and  FIG. 10B  are graphs for explaining operations of the charging apparatus according to a comparison example and an exemplary embodiment of the present invention, respectively, wherein a horizontal axis denotes elapsed time. Herein, VI and II denote an input voltage and an input current of the charging apparatus, respectively, and VO and IO denote an output voltage and an output current of the charging apparatus, respectively. 
     In the comparison example, when both step  217  in  FIG. 6  is omitted and step  220  in  FIG. 4  is omitted, when the number of occurrences of overcurrent in the PFC  130  is less than the second number of occurrences Y, the PFC  130  continues to be operated without changing the current control bandwidth in a state in which overcurrent has occurred in step  230 . Next, when the number of occurrences of overcurrent in the PFC  130  is equal to the second number of occurrences Y, the operation of the PFC  130  is stopped at a timing  300 , as illustrated in  FIG. 10A . Next, in the same environment, the PFC  130  is operated again without taking measures to adjust the current control bandwidth so that charging is stopped due to continuous instability of the input current control. 
     Meanwhile, when charging of the battery  20  is impossible due to an unstable phenomenon of the input current control, the current stabilization method  200  according to the above-described exemplary embodiments sequentially lowers the current control bandwidth in step  220  at a timing  310 , as illustrated in  FIG. 10B , and operates the PFC  130  in the lowered current control bandwidth, being configured for continuously charging the battery  20  even at a timing  320 , as illustrated in  FIG. 10B . 
     Consequently, when input current control is unstable, the current stabilization method  200  according to the above-described exemplary embodiments secures current control stability through active measure of sequentially lowering the current control bandwidth by checking an external system environment and continuously charges the battery  20 , increasing a charging success probability of the battery  20 . Therefore, a situation in which the charging apparatus  100  stops charging the battery  20  and thus inconveniencing a user can be solved. 
     Furthermore, in the current stabilization method  200  according to the exemplary embodiment of the present invention, the first controller  152  is configured to perform the methods as illustrated in  FIG. 4 ,  FIG. 6 ,  FIG. 7 ,  FIG. 8 , and  FIG. 9  by software without changing the input filter  110  or without using additional elements so that the charging apparatus  100  is not changed and constituent elements are not added. Therefore, manufacturing costs of the charging apparatus  100  do not increase and does not deteriorate efficiency. As a result, since control stabilization of the vehicle charging apparatus  100  is secured, power source quality of a vehicle may be improved. 
     Furthermore, deterioration of a power factor and a threshold value may be prevented by properly determining the first number of occurrences X and the second number of occurrences Y. 
     The current stabilization method according to the above-described exemplary embodiments may also be implemented by a program recorded in a computer-readable recording medium. 
     In the recording medium in which a program for implementing the current stabilization method performed by the vehicle charging apparatus, which may include a power factor corrector for correcting the power factor of an AC power source and converts an AC voltage of the AC power source into a DC voltage to charge a vehicle battery, is recorded, the program which implements a function of downwardly-adjusting a current control bandwidth of the power factor corrector when the current control bandwidth of the power factor corrector needs to be adjusted is recorded in the recording medium. Furthermore, a computer may read the recording medium. 
     The program recorded in the computer-readable recording medium may further implement a function of determining whether the current control bandwidth of the power factor corrector needs to be adjusted and a function of operating the power factor corrector using the downwardly-adjusted current control bandwidth. 
     The computer-readable recording medium may include all types of storage devices storing data that may be read by a computer system. Examples of the computer-readable medium include a read only memory (ROM), a random access memory (RAM), a compact disc (CD)-ROM, a magnetic tape, a floppy disk, and an optical data storage. Furthermore, the computer-readable recording medium may be distributed over a computer system connected to a network, so that computer-readable code may be stored therein and executed therefrom in a decentralized manner. Functional programs, code, and code segments for implementing telematics control method may be easily derived by programmers skilled in the art. 
     The vehicle charging apparatus, the current stabilization method thereof, and the recording medium in which a program for implementing the method is recorded, according to exemplary embodiments, overcome an unstable phenomenon of current control caused by a system impedance and achieve stable current control performance by adjusting the current control bandwidth of the power factor corrector without changing a circuit configuration of an OBC. Accordingly, when at least one of overcurrent or overvoltage occurs in the power factor corrector in a plurality of unspecified countries or regions, the vehicle battery can be stably charged, so that user may conveniently charge the battery and power source quality of a vehicle may be improved by securing current control stability without raising manufacturing costs and without reducing efficiency. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “up”, “down”, “upwards”, “downwards”, “internal”, “outer”, “inside”, “outside”, “inwardly”, “outwardly”, “internal”, “external”, “front”, “rear”, “back”, “forwards”, and “backwards” are used to describe features of the exemplary embodiments with reference to the positions of such features as displayed in the figures. 
     The foregoing descriptions of specific exemplary embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teachings. The exemplary embodiments were chosen and described in order to explain certain principles of the invention and their practical application, to thereby enable others skilled in the art to make and utilize various exemplary embodiments of the present invention, as well as various alternatives and modifications thereof. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents.