Battery charging system using a charger and drive control method of the charger thereof

Abstract

Battery charging system using a charger, comprising: an on-board charger (OBC) configured to include a power factor correction (PFC) converter (10) connectable to an output terminal of an alternating current (AC) power unit (60), and a direct current (DC / DC) converter (20) connected between the PFC converter (10) and a high-voltage battery (70); and a controller (30) configured to determine the presence of generation of a charger input voltage VIN output by the AC power unit (60) and determine an output current Ioref or an output power Poref of the DC / DC converter (20) based on the determination of the presence of generation of the charger input voltage VIN, wherein the controller (30), when the charger input voltage VIN is not generated, is configured to determine the output current of the DC / DC converter (20) as a current that is less than the output current when the charger input voltage VIN is generated.

Description

BACKGROUND(a) Technical field

[0001] The present invention relates to a battery charging system using a charger and a charger driving control method thereof that increases the charger driving time during a power failure of the charger mounted on a vehicle. (b) Background of the invention

[0002] As air pollution caused by vehicle exhaust gases increases due to the development of the automotive industry, interest in reducing exhaust gases has grown. Consequently, studies on environmentally friendly vehicles capable of reducing exhaust gases are actively being conducted. Environmentally friendly vehicles include hybrid vehicles, plug-in hybrid vehicles, electric vehicles, fuel cell vehicles, and the like. Among these vehicles, plug-in hybrid vehicles and electric vehicles charge their batteries using a single power source. Consequently, an on-board charger (OBC) is installed inside the vehicle.

[0003] Fig. 1 is an exemplary configuration diagram illustrating a battery charging system using an OBC according to a related art. Fig. Figure 2 is an exemplary graph illustrating states of factors (e.g., output voltage, output current, output power, and the like) related to the charger control upon the occurrence of a momentary power failure of the charger input power in the battery charging system. In particular, graph (a) in Fig. 2 shows a state of an alternating current (AC) input voltage VIN applied to the OBC, and graph (b) shows a state of an output voltage Vo of the OBC. In addition, graph (c) illustrates a state of the output voltage VDC of a power factor corrector (PFC) of the OBC, graph (d) shows a state of the output current Io of the OBC, graph (e) shows a state of the output power Po of the OBC, and graph (f) shows a state of an effective duty cycle (effective duty) Deff for controlling the output voltage of a DC / DC converter.

[0004] The related art battery charging system using the OBC is used to charge a high-voltage battery used as the main battery of an environmentally friendly vehicle. As shown in Fig. 1, the battery charging system includes a PFC converter 1, a direct current (DC / DC) converter 2, a controller 3, a first capacitor 4 and a second capacitor 5.

[0005] The PFC converter 1 is connected to an output terminal of an AC power unit 6 to convert an AC input voltage VIN applied by the AC power unit 6 into a DC voltage VDC and compensate the power factor of the power. The DC / DC converter 2 is connected between an output terminal of the PFC converter 1 and an input terminal of a high-voltage battery 7 to receive a DC voltage VDC output from the PFC converter 1 to convert the DC voltage VDC into a voltage for charging the high-voltage battery 7. Specifically, an isolated DC / DC converter using a full-bridge or half-bridge circuit can be applied to the DC / DC converter 2.

[0006] The first and second capacitors 4 and 6 smooth the outputs of the PFC converter 1 and the DC / DC converter, respectively. The graphs of the output voltage VDC of the PFC converter 1 and the output voltage Vo of the DC / DC converter 2 (or OBC) shown in Fig. 2 illustrate voltages smoothed by using the first and second capacitors 4 and 5. The controller 3 is configured to receive the AC voltage VIN output from the AC power unit 6 and the output voltage VDC of the PFC converter 1 to operate the PFC converter 1, and receive the output voltage Vo of the DC / DC converter 2 to operate the DC / DC converter 2. Specifically, the PFC converter 1 is configured to receive an input current applied by the controller 3, and the DC / DC converter 2 is configured to receive the output current applied by the controller 3.

[0007] The battery charging system of the related art configured as described above uses a control technique for maintaining the existing state when the supply of the AC input voltage to the OBC is suspended due to a momentary power interruption or a momentary power failure (ie, a control technique for maintaining a drive state of the OBC to be identical to that before the supply of the AC input voltage VIN of the OBC is suspended). Specifically, in the Fig. 1, the output voltage VDC of the PFC converter 1 is used as the input voltage of the DC / DC converter 2. Consequently, the output voltage VDC becomes an important factor for determining a drive time of the charger.

[0008] In the battery charging system, the minimum voltage VDC_min capable of continuously driving the OBC should be maintained for a few microseconds (µs) or more to prevent malfunction and damage to the OBC by detecting and storing the driving state of the OBC when the charger input is interrupted. If the power supply is interrupted due to the AC input voltage VIN of the OBC being cut off, this is equivalent to no input voltage VIN of the PFC converter 1. As a result, the PFC converter 1 is in an uncontrollable state due to the loss of input, and the controller 3 cannot adjust the output voltage VDC of the PFC converter 1.

[0009] In other words, in the related art battery charging system, the charging operation of the OBC is controlled identically to the existing state (state where the AC input voltage VIN is on) even when the AC input voltage VIN is off, and therefore, the voltage of the first capacitor 4 is abruptly reduced. As a result, the output voltage VDC of the PFC converter 1 decreases to less than the minimum voltage VDC_min. Therefore, a minimum drive time for detecting and managing the drive state of the charger may not be possible. If the OBC mounted on the vehicle does not receive the input voltage VIN due to a momentary power failure or the like, the drive state of the OBC cannot be accurately detected. As a result, a malfunction of the OBC may be caused, and therefore, the vehicle may be in a dangerous situation.

[0010] Therefore, in the battery charging system of the related art, a method of increasing the energy stored in the first capacitor 4 by increasing the capacitance of the first capacitor 4 is used to delay the time at which the output voltage VDC of the PFC converter 1 reaches the minimum voltage VDC_min and to ensure the minimum drive time of the OBC when the supply of the AC input voltage VIN is suspended. However, this causes an increase in cost.

[0011] Furthermore, EP 2 340 961 A2 discloses a battery charging system that uses a charger, comprising: an on-board charger (OBC) configured to include a PFC converter connectable to an output terminal of an AC power unit, and a DC / DC converter connected between the PFC converter and a high-voltage battery; and a controller configured to determine the presence of generation of a charger input voltage VIN output by the AC power unit and determine an output current Ioref or an output power Poref of the DC / DC converter based on determining the presence of generation of the charger input voltage VIN.

[0012] DE 10 2015 205 633 A1 discloses a power supply device comprising a power factor correction circuit having a capacitor and correcting a power factor of a power; a DC-DC converter having a switching element and stepping up or stepping down an output voltage of the power factor correction switch; a control unit; and a voltage detection unit that detects a voltage of an input side of the power factor correction circuit. The control unit controls the switching element such that an output voltage of the DC-DC converter is gradually reduced upon termination of operation of the DC-DC converter in a normal state in which the voltage detection unit detects no voltage lower than a predetermined value.When the voltage detection unit detects a voltage lower than the specified value, the control unit immediately turns off the switching element to stop the operation of the DC-DC converter.

[0013] US 2013 / 0 016 531 A1 describes a power factor correction circuit configured to correct a power factor; a DC / DC converter configured to convert an output voltage of the power factor correction circuit into another DC voltage; an input voltage detector configured to detect an input voltage input to the power factor correction circuit;and an output voltage controller of the power factor correction circuit configured to generate a voltage command for controlling the output voltage of the power factor correction circuit based on a value of the detected input voltage, an output current value to a load connected to an output of the DC / DC converter, or an output power value of the load, and a set value of an input voltage short-circuit output hold time, and output the voltage command to the power factor correction circuit.;

[0014] It is known from US 2002 / 0 071 300 A1 that the energy stored in the energy storage capacitors of a power supply during the hold-up time can be improved by providing two groups of energy storage capacitors and connecting one group of capacitors to the input of a hold-up time extension circuit, the output of which is connected to the other group of energy storage capacitors. Each group of energy storage capacitors can consist of a single capacitor or of a series of capacitors connected in parallel. The hold-up time extension circuit is designed such that its output is regulated to a voltage lower than the minimum regulation voltage of the output stage's DC-DC converter. Therefore, the hold-up time extension circuit is inactive in normal operating mode, i.e., when the input voltage is applied.In normal operating mode, the two capacitor groups are connected in parallel so that their voltages are equal.

[0015] US 2006 / 0 039 172 A1 provides a circuit for increasing the blocking capacitor hold-up time in a converter circuit, the converter circuit comprising an input circuit for providing a DC bus voltage and a DC blocking capacitor connected across the output of the input circuit, and further comprising an output DC converter circuit having an input coupled to the DC bus and providing an output voltage, the circuit comprising a boost converter circuit having an input coupled across the DC blocking capacitor and an output coupled to the input of the output DC converter stage.

[0016] Finally, EP 2 884 619 A1 discloses a device for controlling the charge of a battery. This device includes an input unit configured to convert the input power from alternating current (AC) to direct current (DC). A first converter is configured to store or output the DC power, and a circuit unit is configured to filter or amplify the output power based on a normal operating state or a momentary power failure state of the AC input power. Furthermore, a second converter is configured to convert the filtered or amplified power and supply the power to a high-voltage battery. OVERVIEW

[0017] It is the object of the present invention to provide a battery charging system using a charger and a drive control method of the charger thereof, which extend a drive time of the charger upon occurrence of an instantaneous power failure of the charger input voltage in the battery charging system, so that it may be possible to ensure sufficient time for obtaining and processing more precise information regarding a drive state of the charger and to reduce the capacitance of a capacitor compared with the related art.

[0018] The object is achieved by a charger having the features of claim 1 and a control method of a charger having the features of claim 3. Advantageous further developments can be found in the subclaims.

[0019] In one aspect, the present invention provides a battery charging system using a charger that may include: an on-board charger (OBC) configured to include a power factor correction (PFC) converter connectable to an output terminal of an AC power unit, and a DC / DC converter connected between the PFC converter and a high-voltage battery; and a controller configured to determine the presence of generation of a charger input voltage VIN output from the AC power unit and determine an output current Ioref or an output power Poref of the DC / DC converter based on determining the presence of generation of the charger input voltage VIN.The controller is configured, when no charger input voltage VIN is generated, to determine the output current of the DC / DC converter as a current that is less than the output current when the charger input voltage VIN is generated.

[0020] In an exemplary embodiment, when no charger input voltage VIN is generated, the controller may be configured to limit the output power of the DC / DC converter to a power that is less than the output power when the charger input voltage VIN is generated.

[0021] In another aspect, the present invention provides a drive control method of a charger of a battery charging system including a PFC converter connectable to an output terminal of an AC power unit and a DC / DC converter connected between the PFC converter and a high-voltage battery, the drive control method including: a first process of determining, by a controller, the presence of generation of a charger input voltage VIN output from the AC power unit; and a second process of ensuring, by the controller, a minimum drive time of the charger by determining, as a current or power reduced compared to when the charger input voltage VIN is generated, an output current or power of the DC / DC converter.In an exemplary embodiment, the output current of the DC / DC converter in the second process may be limited to a current that is less than the output current when the charger input voltage VIN is generated.

[0022] As described above, the battery charging system using the charger according to the present invention has advantages as follows.

[0023] First, the driving time of the OBC can be extended by limiting the charger output current or the charger output power when a momentary power failure or the like occurs, to enable the charger to be driven more stably even during the momentary power failure.

[0024] Secondly, the initial sequence according to the re-activation of the charger cannot be repeated due to an extension of the activation time of the OBC in the event of a momentary power failure or the like.

[0025] Third, the minimum drive time for stable operation of the OBC can be ensured during instantaneous power failure, and thus, it may be unnecessary to increase the capacitance of the first capacitor connected to the output terminal of the PFC converter to form a high output voltage VDC of the PFC converter. Consequently, it may be possible to make the capacitor capacitance smaller than that of related technology, thereby achieving cost reduction. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The above-mentioned and other features of the present invention will now be described with reference to certain exemplary embodiments thereof illustrated in the accompanying drawings, which are given below for illustrative purposes only and thus do not limit the present invention, and in which: Fig. 1 is an exemplary configuration diagram illustrating a conventional battery charging system using an on-board charger (OBC) according to the related art; Fig. 2 is an exemplary graph illustrating states of factors (output voltage, output current, output power, and the like) related to driving the charger upon occurrence of an instantaneous power failure of the charger input voltage in the battery charging system according to the related art; Fig. 3 is an exemplary configuration diagram illustrating a battery charging system using a charger according to an exemplary embodiment of the present invention; Fig. 4 is an exemplary flowchart schematically illustrating a charge driving control method of the battery charging system according to the exemplary embodiment of the present invention; Fig. 5 is an exemplary graph illustrating states of factors (output voltage, output current, output power, and the like) related to driving the charger upon occurrence of a momentary power failure in the battery charging system according to the exemplary embodiment of the present invention; and Fig. 6 is an exemplary graph comparing a time at which the output voltage VDC of a power factor corrector (PFC) converter reaches the minimum voltage VDC_min in the drive control of the charger of the present invention with that of the related art.

[0027] It should be understood that the accompanying drawings are not necessarily to scale, presenting a somewhat simplified representation of various exemplary features illustrative of the basic principles of the invention. The specific embodiments of the present invention disclosed herein, including, for example, particular dimensions, orientations, locations, and shapes, will be determined in part by the particular intended application and environment of use. In the figures, reference numerals refer to like or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION

[0028] It is to be understood that the term "vehicle" or "vehicular" or other similar term used herein includes motor vehicles in general, such as passenger cars, which include off-road vehicles (SUVs), buses, trucks, various business cars, watercraft which include a variety of boats and vessels, aircraft, and the like, and includes hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from feedstocks other than petroleum). As referred to herein, a hybrid vehicle is a vehicle that has two or more power sources, such as both gasoline-powered and electric-powered vehicles.

[0029] While an exemplary embodiment is described using a plurality of units to perform the exemplary process, it is understood that the exemplary processes may also be performed by one or more modules. Furthermore, it is understood that the term controller / controller refers to a hardware device including a memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute the modules to perform one or more processes described below.

[0030] Additionally, the control logic of the present invention may be embodied as non-transitory computer-readable media on a computer-readable medium containing executable program instructions executed by a processor, controller, or the like. Examples of computer-readable mediums include, but are not limited to, read-only memory, random access memory, compact disc read-only memory (CD-ROMs), magnetic tape, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable recording medium may also be distributed in network-coupled computer systems such that the computer-readable medium is stored and executed in a distributed manner, e.g., by a telematics server or a controller area network (CAN).

[0031] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. As used herein, the singular forms "a" and "an" are intended to include the plural forms unless the context clearly indicates otherwise. It will also be understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of the recited features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed elements.

[0032] Reference will now be made in detail to various exemplary embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in connection with exemplary embodiments, it will be understood that the present description is not intended to limit the invention to these exemplary embodiments. On the contrary, the invention is intended to cover not only the exemplary embodiments, but also various alternatives, modifications, equivalents, and other embodiments that may be included within the spirit and scope of the invention as defined by the appended claims.

[0033] The present invention provides a battery charging system using a vehicle-mounted charger and a charger drive control method. When the power supplied to the charger is turned off, the minimum drive time of the charger can be ensured, thus improving stability and productivity. Therefore, in the present invention, the drive time of an on-board charger (OBC) can be extended by limiting the output current Io or the output power Po of the charger according to the presence of generation of a charger input voltage VIN (or on / off condition).

[0034] As in Fig. 3, a battery charging system according to an exemplary embodiment of the present invention may be used to control the charging of a high-voltage battery 70 within a vehicle that utilizes an off-board AC power unit 60. The battery charging system may include a power factor correction (PFC) converter 10 connectable to an output terminal of the AC power unit 60, a DC / DC converter 20, a controller 30, a first capacitor 40, and a second capacitor 50.

[0035] The AC power unit 60 is an external power source and may, for example, use a home (e.g., garage or similar) power source. When connected to an OBC, the AC power unit 60 may be configured to output a charger input voltage VIN to an input terminal of the PFC converter 10. The PFC converter 10 may be connected to the output terminal of the AC power unit 60 to convert an AC input voltage VIN applied by the AC power unit 60 to a DC voltage VDC while simultaneously compensating the power factor. The DC / DC converter 20 may be connected between an output terminal of the PFC converter 10 and an input terminal of the high-voltage battery 70. The DC / DC converter 20 may be configured to receive the DC voltage VDC output from the PFC converter 10 and convert the received DC voltage VDC into a voltage for charging the high voltage battery 70.In particular, an isolated DC / DC converter using a full-bridge or half-bridge circuit may be applied to the DC / DC converter 20.

[0036] The first capacitor 40 may be connected to the output terminal of the PFC converter 10 to smooth an output of the PFC converter 10, and the second capacitor 50 may be connected to an output of the DC / DC converter 20 to smooth an output of the DC / DC converter 20 applied to the high voltage battery 70.

[0037] The controller 30 may be configured to actuate the OBC. Specifically, the controller 30 may be configured to determine the presence of generation of the charger input voltage VIN output from the AC power unit 60, and then determine an output current Ioref or an output power Poref of the DC / DC converter 20 based on the determination result, thereby adjusting the consumption amount of the energy stored in the first capacitor 40. Further, the controller 30 may be connected to the input terminal of the PFC converter 10 to sample the charger input voltage VIN generated in the AC power unit 60, thereby determining the presence of generation of the charger input voltage VIN.For example, although not shown in this figure, the controller 30 may be configured to determine the presence of generation of the charger input voltage VIN output from the AC power unit 60 using a sensor (not shown) connected to the input terminal of the PFC converter 10.

[0038] In relation to Fig. 4, in response to determining that the charger input voltage is being generated (i.e., when normal driving of the OBC is possible), the controller 30 may be configured to determine the output current Ioref of the DC / DC converter 20 as the on current Iref_on, so that the output current Io of the DC / DC converter 20 becomes the on current Iref_on. In response to determining that the charger input voltage VIN is not being generated (i.e., when driving the OBC is not possible due to a momentary power failure) or the like, the controller 30 may be configured to determine the output current Ioref of the DC / DC converter 20 as a current that is less than the output current when the charger input voltage VIN is being generated.

[0039] Regarding the Fig. 4 and graph (d) in Fig. 5, the controller 30 may be configured to determine the output current Ioref provided to the DC / DC converter 20 when the charger input voltage VIN is not generated as an off current Iref_off that is less than the on current Iref_on provided when the charger input voltage VIN is generated, so that the output current Io of the DC / DC converter 20 becomes the off current Iref_off. In particular, the output current Io may be set as the off current Iref_off during the minimum drive time of the charger (e.g., the minimum drive time for detecting and storing a drive state of the charger during a momentary power failure).

[0040] When the charger input voltage VIN is not generated, the PFC converter 10 cannot provide power as an output due to an input loss, and as a result, the DC / DC converter 20 may be configured to use a charging voltage of the first capacitor 40 as the input voltage. The controller 30 may be configured to keep the charger output current Io as the off-current Iref_off lower than the on-current Iref_on when the charger input voltage VIN is not generated in order to minimize the drop in the output voltage VDC (e.g., the amount of voltage reduction per unit time) generated by the discharging of the first capacitor 40, which can be significantly reduced compared to the related art. Consequently, the time at which the output voltage VDC reaches the minimum voltage VDC_min (e.g.,the minimum voltage required to generate the charger output voltage Vo) is reached, thereby extending the charger activation time.

[0041] In particular, a minimum current for normal operation of the OBC, i.e., a minimum current required to maintain the charger output voltage Vo to be approximately equal to the voltage before the instantaneous power failure occurs (i.e., when the charger input voltage VIN is generated), and a minimum current for maximally delaying the time at which the output voltage VDC of the first capacitor 40 reaches the minimum voltage VDC_min, may be applied to the off current Iref_off.

[0042] In relation to Fig. 5, the controller 30 may be configured to reduce the output power Poref provided to the DC / DC converter 20 when the charger input voltage VIN is not generated to a power that is less than the output power when the charger input voltage VIN is generated. Consequently, the controller 30 may be configured to limit the charger output current Io to the current that is less than the output current provided when the charger input voltage VIN is generated, i.e., the off-current Iref_off. Further, Fig. 5 is an exemplary graph illustrating states of factors related to driving the OBC when a power failure of the charger input voltage VIN occurs. Graph (a) illustrates a state of the AC input voltage VIN applied to the PFC converter of the OBC. Graph (b) illustrates a state of the charger output voltage Vo. Graph (c) illustrates a state of the PFC converter output voltage VDC. Graph (d) illustrates a state of the charger output current Io. Graph (e) illustrates a state of the charger output power Po. Finally, graph (f) illustrates a state of an effective duty cycle Deff for controlling the output voltage of the DC / DC converter.

[0043] Furthermore, in the present invention, the controller 30 may be configured to determine and adjust the output current Ioref or the output power Poref of the DC / DC converter 20 according to the occurrence of the generation of the charger input voltage VIN. Thus, during normal driving (e.g., without failure) in which the charger input voltage VIN is generated and the OBC is normally operated (e.g., without failure), the charger output current Io may be maintained at a substantially constant value. During a momentary power failure or the like in which the charger input voltage VIN is not generated, the charger output current Io may be limited to the minimum value (off-current Iref_off) to reduce the voltage drop (e.g., amount of decrease in voltage per unit time) of the first capacitor 40 that generates the output voltage VDC.Consequently, it may be possible to delay the time at which the output voltage VDC reaches the minimum voltage VDC_min. As a result, it may be possible to extend the charger drive time and ensure the minimum drive time of the OBC.

[0044] When comparing the present invention with the related art with respect to Fig. 6 shows that the control time of the OBC is extended according to the present invention. Fig. 6 is an exemplary graph comparing the states of factors related to driving the OBC according to the present invention upon a power failure of the charger input voltage VIN with those of the related art. Graph (a) illustrates states of the AC input voltage VIN applied to the PFC converter of the OBC. Graph (b) illustrates states of the charger output voltage Vo. Graph (c) illustrates states of the PFC converter output voltage VDC. Finally, graph (d) illustrates states of the charger output current Io.

[0045] When a momentary power failure occurs, the charger input voltage VIN is off (i.e., not generated) and, as a result, the charging voltage of the first capacitor can be used. As shown in Fig. 6, in the related art, the charger output current Io is maintained equal to the current before the power failure occurs (in normal driving) even in the off state of the AC input voltage VIN, and the battery charging is performed equal to the charging before the power failure occurs. Therefore, the charging voltage of the first capacitor 4 is abruptly reduced. As a result, the minimum driving time of the charger is unsatisfactory. On the other hand, in the present invention, as shown in Fig. 6, the controller 30 may be configured to determine the presence of the on / off state of the charger input voltage VIN and reduce the charger output current Io or the charger output power Po to a constant value to gently reduce the charging voltage of the first capacitor 40. As a result, the minimum drive time of the charger can be ensured.

Claims

[1] A battery charging system using a charger comprising: an on-board charger (OBC) configured to include a power factor correction (PFC) converter (10) connectable to an output terminal of an alternating current (AC) power unit (60), and a direct current (DC / DC) converter (20) connected between the PFC converter (10) and a high-voltage battery (70); and a controller (30) configured to determine the presence of generation of a charger input voltage VIN output by the AC power unit (60) and determine an output current Ioref or an output power Poref of the DC / DC converter (20) based on the determination of the presence of generation of the charger input voltage VIN, wherein the controller (30), when the charger input voltage VIN is not generated, is configured to determine the output current of the DC / DC converter (20) as a current that is less than the output current when the charger input voltage VIN is generated. [2] The battery charging system of claim 1, wherein the controller (30) is configured to limit the output power of the DC / DC converter (20) to a power that is less than the output power when the charger input voltage VIN is being generated, when the charger input voltage VIN is not being generated. [3] A drive control method of a charger of a battery charging system including a power factor correction (PFC) converter (10) connectable to an output terminal of an alternating current (AC) power unit (60) and a direct current (DC / DC) converter connected between the PFC converter (10) and a high-voltage battery (70), the drive control method comprising: a first process for determining the presence of generation of a charger input voltage VIN output by the AC power unit (60) by a controller (30); and a second process for ensuring a minimum drive time of the charger by the controller (30) by determining an output current or an output power of the DC / DC converter (20) when the charger input voltage VIN is not generated as a current or power that is reduced compared to when the charger input voltage VIN is generated. [4] The drive control method according to claim 3, wherein in the second process, the output current of the DC / DC converter (20) is limited to a current less than the output current when the charger input voltage VIN is generated. [5] The drive control method according to claim 3, wherein in the second process, when the charger input voltage VIN is not generated, the output power of the DC / DC converter (20) is limited to a power lower than the output power when the charger input voltage VIN is generated.

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