Patent Publication Number: US-2023163333-A1

Title: Apparatus and method for controlling fuel cell system

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     The present application claims priority to Korean Patent Application No. 10-2021-0164814, filed on Nov. 25, 2021, the entire contents of which is incorporated herein for all purposes by this reference. 
     BACKGROUND OF THE PRESENT DISCLOSURE 
     Field of the Present Disclosure 
     The present disclosure relates to an apparatus and a method for controlling a fuel cell system to control the operation of the fuel cell system. 
     Description of Related art 
     In fields such as power generation, ships and aviation, a large-capacity power generation system of Mega Watt (MW) or higher is required. To implement the large-capacity power generation system using a fuel cell system, a plurality of fuel cell systems may be connected to each other in series and/or in parallel to make up the large-capacity power generation system. However, when the plurality of fuel cell systems is connected to each other in series and/or in parallel to make up the large-capacity power generation system, an insulation resistance characteristic of a stack is degraded. 
     The information included in this Background of the present disclosure section is only for enhancement of understanding of the general background of the present disclosure and may not be taken as an acknowledgement 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 disclosure are directed to providing an apparatus and a method for controlling a fuel cell system to control power supply necessary for operation of a balance of plant (BOP) when the fuel cell system is started and stopped. 
     The technical problems to be solved by the present disclosure are not limited to the aforementioned problems, and any other technical problems not mentioned herein will be clearly understood from the following description by those skilled in the art to which the present disclosure pertains. 
     According to an aspect of the present disclosure, an apparatus of controlling a fuel cell system may include a fuel cell system including a fuel cell stack, a balance of plant (BOP) that operates the fuel cell stack, and a fuel cell controller that is configured to control the BOP, a first power converter located between the fuel cell stack and a first voltage battery and including a bidirectional low voltage DC/DC converter, a second power converter located between the fuel cell stack and a second voltage battery to include a single bidirectional DC/DC converter module, and a controller that operates the first power converter or the single bidirectional DC/DC converter module of the second power converter, when the fuel cell system is started or stopped, and controls the first power converter or the single bidirectional DC/DC converter module of the second power converter to supply driving power to the BOP using electrical energy of the first voltage battery or the second voltage battery, wherein an output voltage of the second voltage battery is higher than an output voltage of the first voltage battery. 
     The controller may operate the first power controller in a boost mode, when the fuel cell system is initially started. 
     The first power converter may boost and supply electrical energy stored in the first voltage battery to the BOP. 
     The controller may switch an operation mode of the first power converter from the boost mode to a buck mode, when the start of the fuel cell system is completed. 
     The first power converter may buck and supply electrical energy generated by the fuel cell stack to a load. 
     The second power converter may further include at least one unidirectional DC/DC converter module and a transformer. The controller may be configured to determine whether a current situation is a low temperature situation, when the fuel cell system is stopped, may stop a boost operation of the single bidirectional DC/DC converter module and the at least one unidirectional DC/DC converter module, when it is determined that the current situation is the low temperature situation, may operate the second voltage battery in a discharge mode, and may buck and supply electrical energy stored in the second voltage battery to the BOP using the single bidirectional DC/DC converter module. 
     The fuel cell controller may remove a material remaining in the fuel cell stack, when the current situation is not the low temperature situation or in the low temperature situation, and may control the BOP to block air and hydrogen supplied to the fuel cell stack. 
     According to another aspect of the present disclosure, a method for controlling a fuel cell system to control the fuel cell system including a fuel cell stack, an operation device, and a fuel cell controller may include starting, by a controller, a start procedure or a stop procedure of the fuel cell system, operating, by the controller, a first power converter including a bidirectional low voltage DC/DC converter or a single bidirectional DC/DC converter module of a second power converter based on starting the start procedure or the stop procedure, and supplying, by the first power converter or the single bidirectional DC/DC converter module of the second power converter, driving power to the BOP using electrical energy of a first voltage battery or a second voltage battery. 
     The operating of the first power converter or the second power converter may include operating, by the controller, the first power controller in a boost mode, when starting the start procedure. 
     The supplying of the driving power to the BOP may include boosting and supplying, by the first power converter, electrical energy stored in the first voltage battery to the BOP. 
     The method may further include switching, by the controller, an operation mode of the first power converter from the boost mode to a buck mode, when the start of the fuel cell system is completed, and bucking and supplying, by the first power converter, electrical energy generated by the fuel cell stack to a load. 
     The method may further include operating, by the controller, the single bidirectional DC/DC converter module and at least one unidirectional DC/DC converter module in the second power converter in the boost mode and boosting and outputting, by the single bidirectional DC/DC converter module and the at least one unidirectional DC/DC converter module, electrical energy generated by the fuel cell stack. 
     The operating of the first power converter or the second power converter may include determining, by the controller, whether a current situation is a low temperature situation, when starting the stop procedure, stopping, by the controller, a boost operation of the single bidirectional DC/DC converter module and at least one unidirectional DC/DC converter module in the second power converter, when it is determined that the current situation is the low temperature situation, operating, by the controller, the second voltage battery in a discharge mode, initiating, by the controller, a buck operation of the single bidirectional DC/DC converter module, bucking and supplying, by the single bidirectional DC/DC converter module, electrical energy stored in the second voltage battery to the BOP, and removing, by the BOP, a material remaining in the fuel cell stack under control of the fuel cell controller. 
     The method may further include controlling, by the fuel cell controller, the BOP to block air and hydrogen supplied to the fuel cell stack, after removing the material remaining in the fuel cell stack, when the current situation is not the low temperature situation or in the low temperature situation. 
     The methods and apparatuses of the present disclosure 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 disclosure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a block diagram illustrating a configuration of an apparatus of controlling a fuel cell system according to various exemplary embodiments of the present disclosure; 
         FIG.  2    is a flowchart illustrating a method for controlling a start of a fuel cell system according to an exemplary embodiment of the present disclosure; and 
         FIG.  3    is a flowchart illustrating a method for controlling stop of a fuel cell system according to another exemplary embodiment of the present disclosure. 
     
    
    
     It may 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 present disclosure. The specific design features of the present disclosure as included 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 disclosure throughout the several figures of the drawing. 
     DETAILED DESCRIPTION 
     Reference will now be made in detail to various embodiments of the present disclosure(s), examples of which are illustrated in the accompanying drawings and described below. While the present disclosure(s) will be described in conjunction with exemplary embodiments of the present disclosure, it will be understood that the present description is not intended to limit the present disclosure(s) to those exemplary embodiments of the present disclosure. On the other hand, the present disclosure(s) is/are intended to cover not only the exemplary embodiments of the present disclosure, but also various alternatives, modifications, equivalents and other embodiments, which may be included within the spirit and scope of the present disclosure as defined by the appended claims. 
     Hereinafter, various exemplary embodiments of the present disclosure will be described in detail with reference to the exemplary drawings. In the drawings, the same reference numerals will be used throughout to designate the same or equivalent elements. Furthermore, a detailed description of well-known features or functions will be ruled out in order not to unnecessarily obscure the gist of the present disclosure. 
     In describing the components of the exemplary embodiment according to an exemplary embodiment of the present disclosure, terms such as first, second, “A”, “B”, (a), (b), and the like may be used. These terms are only used to distinguish one element from another element, but do not limit the corresponding elements irrespective of the order or priority of the corresponding elements. Furthermore, unless otherwise defined, all terms including technical and scientific terms used herein are to be interpreted as is customary in the art to which the present disclosure belongs. Such terms as those defined in a generally used dictionary are to be interpreted as having meanings equal to the contextual meanings in the relevant field of art, and are not to be interpreted as having ideal or excessively formal meanings unless clearly defined as having such in the present application. 
       FIG.  1    is a block diagram illustrating a configuration of an apparatus of controlling a fuel cell system according to various exemplary embodiments of the present disclosure. 
     The apparatus of controlling the fuel cell system may be mounted on an electrical system (e.g., a ship control system, a train control system, an aviation control system, a large-capacity power generation system, and the like) which operates using electrical energy (power) generated by a fuel cell system  110 . The apparatus of controlling the fuel cell system may control start, run, stop or shutdown, and the like of the fuel cell system  110 . 
     Referring to  FIG.  1   , the apparatus of controlling the fuel cell system may include the fuel cell system  110 , a first power converter  120 , a second power converter  130 , a controller  140 , and the like. 
     The fuel cell system  110  may include a fuel cell stack (hereinafter, referred to as a “stack”)  111 , a balance of plant (BOP)  112 , a fuel cell controller  113 , and the like. 
     The stack  111  may produce electrical energy (i.e., power) by an electrochemical reaction between hydrogen and oxygen. The stack  111  may include two catalyst electrodes, that is, an anode and a cathode. When hydrogen and oxygen are respectively provided to the anode and the cathode, the anode may divide the hydrogen into protons, that is, hydrogen ions and electrons. The hydrogen ions may move to the cathode through an electrolyte layer and may be combined with oxygen in the cathode to produce water (H 2 O). Electrons pass through an external circuit to generate current. 
     The BOP  112  may be subsystems necessary to operate the stack  111 , which may be mounted on the periphery of the stack  111 . The BOP  112  may directly receive electrical energy produced by the stack  111  or may receive electrical energy stored in a low voltage battery LV BATT to operate. Such a BOP  112  may include an air process system (APS), a fuel process system (FPS), a thermal management system (TMS), and the like. The APS may be a system which supplies air (i.e., oxygen) to react with hydrogen to the stack  111 , which may include an air cleaner, an air blower or an air compressor, and the like. The FPS may be a system which supplies hydrogen, which may include a hydrogen tank, a pressure regulator, a hydrogen recirculator, and the like. The TMS may be a system which manages heat generated due to an electrochemical reaction in the stack  111  to allow the stack  111  to maintain a suitable temperature, which may include a radiator, a water pump, an ion filter, a water tank, and the like. 
     The fuel cell controller  113  may control the overall operation of the fuel cell system  110 . The fuel cell controller  113  may include at least one processor and may include a memory located inside and/or outside the fuel cell controller  113 . The memory may be a non-transitory storage medium which stores instructions executed by the at least one processor. The memory may be implemented as at least one of storage media such as a hard disk, a solid state disk (SSD), an embedded multimedia card (eMMC), and/or a universal flash storage (UFS). The at least one processor may be implemented as at least one of processing devices such as an application specific integrated circuit (ASIC), a digital signal processor (DSP), programmable logic devices (PLD), field programmable gate arrays (FPGAs), a central processing unit (CPU), microcontrollers, and/or microprocessors. 
     The fuel cell controller  113  may control the BOP  112  to supply or block fuel (i.e., hydrogen) and/or air to the stack  111 . Furthermore, the fuel cell controller  113  may control the BOP  112  to adjust the amount of hydrogen and/or air supplied to the stack  111 . The fuel cell controller  113  may monitor state(s) of the stack  111  and/or the BOP  112  using various detectors (e.g., a temperature detector, a voltage detector, a current detector, a flow detector, and/or the like) provided in the stack  111  and/or the BOP  112 . 
     The first power converter  120  may supply power to the BOP  112  and/or a low voltage load using electrical energy stored in the low voltage battery LV BATT (e.g., a  12 V battery). At the instant time, the low voltage battery LV BATT may operate in a discharge mode. The first power converter  120  may operate in a boost mode or a buck mode. When operating in the boost mode, the first power converter  120  may convert electrical energy stored in the low voltage battery LV BATT into a high voltage and may supply the high voltage to the BOP  112 . When operating in the buck mode, the first power converter  120  may convert electrical energy stored in the low voltage battery LV BATT into a low voltage and may supply the low voltage to a low voltage load loaded into an electrical system. 
     The first power converter  120  may charge the low voltage battery LV BATT using electrical energy produced by the stack  111  of the fuel cell system  110 . At the instant time, the low voltage battery LV BATT may operate in a charge mode. When the low voltage battery LV BATT operates in the charge mode, the first power converter  120  may operate in the buck mode to convert high voltage electrical energy output from the stack  111  into low voltage electrical energy and store the low voltage electrical energy in the low voltage battery LV BATT. Furthermore, the first power converter  120  may operate in the buck mode to convert high voltage electrical energy output from the stack  111  into low voltage electrical energy and supply the low voltage electrical energy to the low voltage load in the electrical system. 
     The first power converter  120  may be implemented as a bidirectional low voltage direct current (DC)/DC converter (BLDC). When the fuel cell system  110  is initially started (or activated), the first power converter  120  may supply driving power to the BOP  112  using electrical energy stored in the low voltage battery LV BATT. After the start of the fuel cell system  110  is completed, the first power converter  120  may supply driving power to a low voltage electronic part (e.g., a  12 V electronic part) using electrical energy stored in the low voltage battery LV BATT. 
     The second power converter  130  may convert electrical energy output from the stack  111  into high voltage electrical energy and may output the high voltage electrical energy. The second power converter  130  may deliver (or supply) the converted high voltage electrical energy to a high voltage battery HV BATT (e.g., a battery over hundreds of volts) or may supply the converted high voltage electrical energy to a motor M through an inverter IVN. 
     The second power converter  130  may be an insulated DC/DC converter, which may include at least one bidirectional DC/DC converter module  131 , at least one unidirectional DC/DC converter module  132  and  133 , a transformer  134 , and the like. The bidirectional DC/DC converter module  131  may include a bidirectional DC/DC converter circuit to operate in the boost mode or the buck mode. The unidirectional DC/DC converter modules  132  and  133  may be connected to each other in series and/or in parallel. Each of the unidirectional DC/DC converter modules  132  and  133  may include a boost DC/DC converter circuit to operate in the boost mode. Because a diode D 1  and a switch SW are configured as a pair in a capacitor at an output of the bidirectional DC/DC converter module  131 , electrical energy may flow bidirectionally. As one diode D 2  or D 3  is connected to a capacitor at an output of the unidirectional DC/DC converter module  132  or  133  in series, electrical energy may flow unidirectionally. The number of DC/DC converter modules  131  to  133  in the second power converter  130  may be proportional to a power capacity of the fuel cell system  110 . 
     The controller  140  may control the overall operation of the electrical system including the fuel cell system  110 . The controller  140  may include at least one processor and may include a memory located inside and/or outside the controller  140 . The memory may be a storage medium which stores instructions executed by the at least one processor. The memory may be implemented as at least one of storage media such as a hard disk, an SSD, an eMMC, and/or a UFS. The at least one processor may be implemented as at least one of processing devices such as an ASIC, a DSP, PLD, an FPGA, a CPU, microcontrollers, and/or microprocessors. 
     When the electrical system is started or stopped, the controller  140  may perform a start or stop (shutdown) procedure of the fuel cell system  110 . When detecting the start and stop of the electrical system, the controller  140  may transmit a start command or a stop command to the fuel cell system  110 . 
     When receiving a response to the start command from the fuel cell controller  113 , the controller  140  may switch an operation mode of the first power converter  120  to the boost mode to operate the first power converter  120 . As the first power converter  120  operates in the boost mode, the fuel cell system  110  may start the BOP  112  using electrical energy of the low voltage battery LV BATT to activate the stack  111 . The BOP  112  may supply air and hydrogen to the stack  111  to initiate warm-up of the stack  111 . 
     The controller  140  may recognize that the start of the fuel cell system  110  is completed. In other words, when the warm-up of the stack  111  is completed, the controller  140  may determine that the start of the fuel cell system  110  is completed. The controller  140  may receive information indicating whether the warm-up of the stack  111  is completed from the fuel cell controller  113 . 
     When the start of the fuel cell system  110  is completed, the controller  140  may switch the operation mode of the first power converter  120  from the boost mode to the buck mode. As the first power converter  120  transitions to the buck mode, it may charge the low voltage battery LV BATT using electrical energy output from the stack  111  or may supply driving power to a 12V electronic part. 
     When the start of the fuel cell system  110  is completed, the controller  140  may operate the second power converter  130  in the boost mode to supply driving power to the electrical system using electrical energy generated by the fuel cell system  110 . After the fuel cell system  110  is activated, the controller  140  may control the second power converter  130  to boost and supply electrical energy generated by the fuel cell system  110  to the electrical system. 
     When receiving a response (e.g., an acknowledge character (ACK)) to the stop command from the fuel cell controller  113 , the controller  140  may determine whether the fuel cell system  110  is stopped in a low temperature situation based on the received response. The fuel cell controller  113  may measure an external temperature using a temperature detector. When the measured external temperature is less than a predefined threshold temperature, the fuel cell controller  113  may determine a current situation as a low temperature situation. When transmitting a response message (or an ACK message) for the stop command of the controller  140 , the fuel cell controller  113  may transmit the result of determining the low temperature situation together. 
     When the current situation is the low temperature situation, the controller  140  may stop the fuel cell system  110  depending on a low temperature shutdown procedure. The controller  140  may stop the operation of the fuel cell system  110  using the boost mode of the at least one unidirectional DC/DC converter module  132  and  133  in the second power converter  130 . Furthermore, the controller  140  may stop the output of the stack  111 . 
     The controller  140  may operate the high voltage battery HV BATT in the discharge mode and may switch the operation mode of the single bidirectional DC/DC converter module  131  in the second power converter  130  from the boost mode to the buck mode. The controller  140  may control the bidirectional DC/DC converter module  131  to supply power to the BOP  112  using electrical energy stored in the high voltage battery HV BATT. The controller  140  may control the fuel cell controller  113  to operate the BOP  112  to remove a material remaining in the stack  111 . The fuel cell controller  113  may control the BOP  112  to block air and hydrogen supplied to the stack  111  depending on an instruction of the controller  140 . 
     When the stop of the fuel cell system  110  is completed, the controller  140  may complete the stop of the electrical system. When the removal of the material remaining in the stack  111  is completed, the fuel cell system  110  may determine that its stop is completed and may transmit a message indicating that the stop of the fuel cell system  110  is completed to the controller  140 . The controller  140  may determine that the stop of the fuel cell system  110  is completed by the message received from the fuel cell system  110 . 
       FIG.  2    is a flowchart illustrating a method for controlling a start of a fuel cell system according to an exemplary embodiment of the present disclosure. 
     Referring to  FIG.  2   , in S 100 , a controller  140  of  FIG.  1    may start an electrical system. When detecting a start event generated outside or inside the electrical system, the controller  140  may start the electrical system. The controller  140  may transmit a message (or a signal) indicating the start of the electrical system to a fuel cell system  110  of  FIG.  1   . 
     When the electrical system is started, in S 110 , a fuel cell controller  113  of the fuel cell system  110  may start the fuel cell system  110 . The fuel cell controller  113  may start a start procedure of the fuel cell system  110  depending on an instruction of the controller  140 . 
     In S 120 , the fuel cell controller  113  may determine whether cold start of fuel cell system  110  is performed. When the determination of whether the cold start is performed is completed, the fuel cell controller  113  may transmit a message (or a signal) for providing a notification of it to the controller  140 . 
     In S 130 , the controller  140  may operate a first power converter  120  of  FIG.  1    in a boost mode to supply power to a BOP  112  of  FIG.  1   . The first power converter  120  may boost and supply electrical energy stored in a low voltage battery LV BATT of  FIG.  1    to the BOP  112 . The first power converter  120  may be implemented as a bidirectional low voltage DC/DC converter. 
     In S 140 , the fuel cell controller  113  may control the BOP  112  under an instruction of the controller  140  to supply air and hydrogen to a stack  111  of  FIG.  1   . When power is supplied to the BOP  112 , the controller  140  may instruct the fuel cell controller  113  to supply air and hydrogen. The fuel cell controller  113  may control the BOP  112  to supply air and hydrogen to the stack  111 . The stack  111  my start warm-up using the air and hydrogen. 
     In S 150 , the fuel cell controller  113  may complete the start of the fuel cell system  110 . When the warm-up of the stack  111  is completed, the fuel cell controller  113  may determine that the start of the fuel cell system  110  is completed. The fuel cell controller  113  may transmit a message indicating that the start of the fuel cell system  110  is completed to the controller  140 . 
     When the start of the fuel cell system  110  is completed, in S 160 , the controller  140  may switch the operation mode of the first power converter  120  from the boost mode to a buck mode. When the operation mode switches to the buck mode, the first power converter  120  may charge the low voltage battery LV BATT using electrical energy output from the stack  111  or may supply driving power to a low voltage load in the electrical system. 
     In S 170 , the controller  140  may operate a second power converter  130  of  FIG.  1    in the boost mode to supply power to the electrical system. The second power converter  130  may boost and supply electrical energy output from the stack  111  to the electrical system. 
     According to the above-mentioned embodiment, when the fuel cell system  110  is initially started, it needs to supply power to the BOP  112  to activate the stack  111 . At the instant time, because it is unable for an apparatus of controlling a fuel cell system to use electrical energy stored in a high voltage battery HV BATT of  FIG.  1   , the apparatus of controlling the fuel cell system may operate the BOP  112  using electrical energy stored in the low voltage battery LV BATT and may proceed with activating the stack  111 . 
       FIG.  3    is a flowchart illustrating a method for controlling stop of a fuel cell system according to another exemplary embodiment of the present disclosure. 
     In S 200 , a controller  140  of  FIG.  1    may stop the operation of an electrical system. When detecting a stop event generated outside or inside the electrical system, the controller  140  may stop (shut down) the electrical system. The controller  140  may transmit a message indicating the stop of the electrical system to a fuel cell controller  113  of a fuel cell system  110  of  FIG.  1   . 
     In S 210 , the fuel cell controller  113  may start a stop procedure of the fuel cell system  110 . The fuel cell controller  113  may start the stop procedure under an instruction of the controller  140 . 
     In S 220 , the fuel cell controller  113  may determine whether a current situation is a low temperature situation. The fuel cell controller  113  may transmit the result of determining whether the current situation is the low temperature situation to the controller  140 . The fuel cell controller  113  may measure an external temperature by a temperature detector. When the measured external temperature is less than a predefined threshold temperature, the fuel cell controller  113  may determine the current situation as the low temperature situation. 
     When it is determined that the current situation is the low temperature situation, in S 230 , the controller  140  may initiate a low temperature shutdown procedure. The controller  140  may determine whether the current situation is the low temperature situation based on the result received from the fuel cell controller  113 . When the stop of the fuel cell system  110  is started in the low temperature situation, the controller  140  my stop (shut down) the fuel cell system  110  depending on a predetermined low temperature shutdown procedure. 
     In S 240 , the controller  140  may stop a boost operation of a second power converter  130  of  FIG.  1    and an output of a stack  111  of  FIG.  1   . The controller  140  may stop operating a plurality of DC/DC converter module  131  and  133  in the second power converter  130  in a boost mode. Furthermore, the controller  140  may request the fuel cell controller  113  to stop the output of the stack  111 . 
     Thereafter, in S 250 , the controller  140  may operate a high voltage battery HV BATT of  FIG.  1    and may switch the operation mode of the second power converter  130  from the boost mode to a buck mode. The controller  140  may switch the operation mode of the single bidirectional DC/DC converter module  131  in the second power converter  130  from the boost mode to the buck mode. 
     In S 260 , the controller  140  may supply power to a BOP  112  of  FIG.  1    using the second power converter  130 . The single bidirectional DC/DC converter module  131  of the second power converter  130  may supply driving power to the BOP  112  using electrical energy of the high voltage battery HV BATT. 
     In S 270 , the fuel cell controller  113  may control the BOP  112  to remove materials remaining in the stack  111 . When power is supplied to the BOP  112 , the fuel cell controller  113  may control the BOP  112  to remove a material remaining in the stack  111 . 
     In S 280 , the fuel cell controller  113  may block air and hydrogen supplied to the stack  111 . The fuel cell controller  113  may control the operation of the BOP  112  to block air and hydrogen supplied to the stack  111 . 
     In S 290 , the fuel cell controller  113  may determine that the stop of the fuel cell system  110  is completed. When the material remaining in the stack  111  is removed and when air and hydrogen supply to the stack  111  is stopped, the fuel cell controller  113  may determine that the generation of the stack  111  is stopped to determine that the stop of the fuel cell system  110  is completed. 
     When the stop of the fuel cell system  110  is completed, in S 300 , the controller  140  may complete the stop of the electrical system. 
     When the current situation is not the low temperature situation in S 220 , in S 280  and S 290 , the fuel cell controller  113  may control the BOP  112  to block air and hydrogen supplied to the stack  111  and stop the fuel cell system  110 . As the fuel cell system  110  is stopped, the controller  140  may stop the electrical system. 
     According to the above-mentioned embodiment, as one of multiple unidirectional DC/DC converter modules making up the second power converter  130  is designed to change to the bidirectional DC/DC converter module  131  using the configuration of the second power converter  130  previously including multiple modules, power may be supplied to the BOP  112  using the bidirectional DC/DC converter module  131  when the fuel cell system  110  is stopped in a low temperature. As a result, power may be supplied to the BOP  112  using electrical energy stored in the high voltage battery HV BATT, when the fuel cell system  110  is stopped in a low temperature interval, without adding a separate converter or changing the entire converter circuit and control logic. 
     According to various exemplary embodiments of the present disclosure, the apparatus of controlling the fuel cell system may supply necessary power to the BOP using a bidirectional low voltage converter when the fuel cell system is started and may supply power to the BOP using a single bidirectional converter in an insulated converter when the fuel cell system is stopped, thus improving a problem in which an insulation resistance characteristic of the stack is degraded. 
     Furthermore, the term related to a control device such as “controller”, “control apparatus”, “control unit”, “control device”, “control module”, or “server”, etc refers to a hardware device including a memory and a processor configured to execute one or more steps interpreted as an algorithm structure. The memory stores algorithm steps, and the processor executes the algorithm steps to perform one or more processes of a method in accordance with various exemplary embodiments of the present disclosure. The control device according to exemplary embodiments of the present disclosure may be implemented through a nonvolatile memory configured to store algorithms for controlling operation of various components of a vehicle or data about software commands for executing the algorithms, and a processor configured to perform operation to be described above using the data stored in the memory. The memory and the processor may be individual chips. Alternatively, the memory and the processor may be integrated in a single chip. The processor may be implemented as one or more processors. The processor may include various logic circuits and operation circuits, may process data according to a program provided from the memory, and may generate a control signal according to the processing result. 
     In various exemplary embodiments of the present disclosure, the control device may be implemented in a form of hardware or software, or may be implemented in a combination of hardware and software. 
     Furthermore, the terms such as “unit”, “module”, etc. Included in the specification mean units for processing at least one function or operation, which may be implemented by hardware, software, or a combination thereof. 
     For convenience in explanation and accurate definition in the appended claims, the terms “upper”, “lower”, “inner”, “outer”, “up”, “down”, “upwards”, “downwards”, “front”, “rear”, “back”, “inside”, “outside”, “inwardly”, “outwardly”, “interior”, “exterior”, “internal”, “external”, “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. It will be further understood that the term “connect” or its derivatives refer both to direct and indirect connection. 
     The foregoing descriptions of specific exemplary embodiments of the present disclosure have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the present disclosure 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 to explain certain principles of the present disclosure and their practical application, to enable others skilled in the art to make and utilize various exemplary embodiments of the present disclosure, as well as various alternatives and modifications thereof. It is intended that the scope of the present disclosure be defined by the Claims appended hereto and their equivalents.