Method and system for checking a fuel cell stack

Abstract

Method for checking a fuel cell stack, comprising: Determine, by means of a control system, a point in time at which a check of a fuel cell stack is required, based on several factors; Stopping, by control, an operation of a power conversion control (230) which stops a charging and discharging of a high voltage battery between the high voltage battery and the fuel cell stack; Driving, by means of the control, a motor set to an initial efficiency value during a predetermined initial reference period from the time of the diagnostic determination; Driving, by means of the control system, the motor set to a second efficiency value after the first reference period has elapsed; and Checking, by means of the control, a state of the fuel cell stack based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and second efficiency value.

Description

BACKGROUND 1. Field of the invention

[0001] The present invention relates in general to a method and system for checking a fuel cell stack and in particular to a method and system for more accurately checking the state of a fuel cell stack based on a control logic between control devices. 2. Description of the state of the art

[0002] A fuel cell vehicle is a type of vehicle that includes a fuel cell stack, which consists of several fuel cells used as a single energy source; a fuel supply system that provides hydrogen, the fuel for the fuel cell stack; an air supply system that provides oxygen, the oxidizer necessary for electrochemical reactions; and a water and heat management system that regulates the temperature of the fuel cell stack. The fuel supply system decompresses compressed hydrogen within a hydrogen tank and delivers the hydrogen to a fuel electrode (anode) of the stack. Simultaneously, the air supply system delivers air drawn in from outside by an air blower to an air electrode (cathode) of the stack.

[0003] When hydrogen and air are supplied to the fuel electrode and air electrode of the stack, respectively, hydrogen ions are extracted at the fuel electrode through a catalytic reaction. The separated hydrogen ions are then fed to the anode through an electrolyte membrane, and the hydrogen ions and electrons from the fuel electrode undergo an electrochemical reaction with oxygen to generate electrical energy at the anode. Specifically, electrochemical oxidation of hydrogen at the fuel electrode and electrochemical reduction of oxygen at the air electrode cause the electrons to move, and this movement of electrons generates electricity and heat. Additionally, water vapor or water is produced through the chemical action of hydrogen and oxygen combining.

[0004] An exhaust device is arranged to expel unreacted hydrogen and oxygen, as well as byproducts generated during the electrical energy production process, such as steam, water, and heat. Gases, including steam, hydrogen, and oxygen, are also released into the air through a ventilation hood. Components for operating the fuel cell, such as an air blower, a hydrogen recirculation blower, a water pump, and the like, are connected to a main bus connector to enable fuel cell operation. The main bus connector can be equipped with various relays for power interruption and a power supply, and a diode to prevent reverse current.

[0005] Dry air supplied by the air blower is humidified by a humidifier and then fed to a cathode of the fuel cell stack. The cathode's exhaust gas, which has a high humidity level due to the water it produces, is transferred to the humidifier and can be used to humidify dry air supplied to the cathode by the air blower. Furthermore, the condition and performance of a fuel cell stack are determined by a highly precise response to operating conditions such as air temperature, coolant temperature, and current. Continuous operation under poor operating conditions causes a decrease in fuel cell performance and can lead to a potential failure to generate sufficient output power to be required by a driver in the short term.In the long term, this can also lead to a deterioration in durability and a reduction in the life cycle of the fuel cell.

[0006] Furthermore, fuel cell stack drying is due to two main causes: drying at substantially high temperature and high power, and drying at substantially low power. Drying at high temperature and high power results from a loss of heat balance, while drying at low power results from an oversupply of air. When fuel cell stack drying occurs, the stack's power output decreases, and the time required to restore normal performance increases. Therefore, it is necessary to detect whether fuel cell stack drying is occurring and to establish conditions to enable rapid recovery from drying by driving the stack to restore it.

[0007] To check the condition of the fuel cell stack, dehydration caused by long-term deterioration of the fuel cell stack and water deficiency within a membrane electrode assembly can be determined using an ohmic value. To measure the ohmic value, an interruption device placed between the fuel cell stack and an external power consumption device can be used. The ohmic value can be measured based on a sudden voltage increase resulting from a temporary interruption of current flow in the fuel cell stack. However, the use of the interruption device can create a heat problem within the external power consumption device and may contribute to a lack of durability of either the interruption device or the external power consumption device.

[0008] From JP 2008 - 123 783 A, a method for checking a fuel cell stack is known, comprising: determining, by a controller, a time at which a check of a fuel cell stack is required, based on several factors; driving, by the controller, a motor set to a first efficiency value for a predetermined first reference period from the time of the diagnostic determination; driving, by the controller, the motor set to a second efficiency value after the first reference period has elapsed; checking, by the controller, a state of the fuel cell stack based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value. OVERVIEW

[0009] Accordingly, the present invention has been made taking into account the above problems, and it is an object of the present invention to provide a method and system for checking the state of a fuel cell stack using cooperative / interacting control logic between controllers without an external energy consumption device and resistance analysis device.

[0010] The problem is solved by a method for checking a fuel cell stack with the features of claims 1 or 7 and a system for checking a fuel cell stack with the features of claim 8. Advantageous further developments are found in the dependent claims.

[0011] A method for checking a fuel cell stack according to an embodiment of the present invention comprises: determining a time at which a check of a fuel cell stack is required based on several factors; stopping, by means of the control, the operation of a power conversion control that stops charging and discharging a high-voltage battery between the high-voltage battery and the fuel cell stack; driving a motor set to a first efficiency value for a predetermined first reference period from the time of determining that a check is required; driving the motor set to a second efficiency value after the first reference period has elapsed;and checking the condition of the fuel cell stack based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value.

[0012] The process for determining when a fuel cell stack check is required may include determining whether a deviation in the fuel cell stack's output current is less than a predetermined deviation. The process for driving a motor set to the first efficiency value may be carried out in response to a determination that fuel cell stack diagnostics are required and that the output current deviation is less than the predetermined deviation. Specifically, the first efficiency value may be less than the second efficiency value. The motor output power in the process for driving the motor set to the first efficiency value may be the same as in the process for driving the motor set to the second efficiency value.

[0013] The process for verifying the condition of the fuel cell stack can include collecting data related to voltage deviation by measuring the voltage deviation of the fuel cell stack and verifying the condition of the fuel cell stack by analyzing a resistance value based on the collected data. The procedure can include resuming operation of the power conversion control when the first reference period and second reference period have elapsed.

[0014] Furthermore, a method for checking a fuel cell stack according to a further embodiment of the present invention comprises: determining whether a deviation of an output current of the fuel cell stack is less than a predetermined deviation, whether a check of the fuel cell stack is necessary, and whether a motor control and power conversion control are in a normal state; transmitting instructions from the motor control to initiate a diagnosis of the fuel cell stack based on the diagnostic determination and stopping operation of the power conversion control, wherein the instruction to drive a motor set to a first efficiency value for a predetermined first reference period is provided;Transmitting the instructions from the motor control to terminate a diagnostic check of the fuel cell stack when the predetermined first reference period has elapsed, and resuming operation of the power conversion control, whereby the instruction to drive the motor set to the second efficiency value is provided; and checking the condition of the fuel cell stack based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value.

[0015] Furthermore, a system for checking a fuel cell stack according to an embodiment of the present invention comprises: a fuel cell controller configured to check the state of the fuel cell stack by determining a time at which a fuel cell stack check is required based on several factors; a motor controller configured to drive a motor set to a first efficiency value for a predetermined first reference period based on a diagnostic determination, to drive the motor set to a second efficiency value when the first reference period has elapsed, and to transmit to the fuel cell controller a resistance value, which is analyzed based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value;and a power conversion controller configured to regulate the charging and discharging of a high-voltage battery between the high-voltage battery and the fuel cell stack. The fuel cell controller is configured to determine whether the power conversion controller and the motor controller are operating normally. The fuel cell controller is further configured to monitor the fuel cell's condition based on the transmitted resistance value.

[0016] The fuel cell controller can also be configured to determine whether a deviation in the output current of the fuel cell stack is less than a predefined deviation. Additionally, the fuel cell controller can be configured to operate the motor controller to drive the motor, which is set to an initial efficiency value, when a check of the fuel cell stack is required and the deviation in the output current is less than the predefined deviation.

[0017] The system may further include a power conversion controller configured to charge / discharge a high-voltage battery between the high-voltage battery and the fuel cell stack, and the fuel cell controller may be configured to determine whether the power conversion controller and the motor controller are in a normal state. The fuel cell controller may further be configured, upon determining that the power conversion controller and motor controller are in a normal state, to stop the operation of the power conversion controller and to operate the motor controller to drive the motor set to the first efficiency value.

[0018] The first efficiency value can be lower than the second efficiency value. The motor's output power when driving the motor set to the first efficiency value can be the same as when driving the motor set to the second efficiency value. The fuel cell controller can be configured to resume operation of the power conversion controller once the first and second reference periods have elapsed.

[0019] A method for monitoring a fuel cell stack according to an embodiment of the present invention has the effect that an ohmic value is analyzed by cooperative control logic under a fuel cell controller, motor controller, and power conversion controller without the need for a separate energy consumption device and ohmic value analyzer. Consequently, a durability problem related to the external energy consumption device can be solved. Furthermore, it may be possible to continuously and more accurately monitor the condition of the fuel cell stack using the current configuration of the fuel cell system without additional hardware, even if the deviation in the output current of the fuel cell stack is substantially small. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The above and further tasks, features and advantages of the present disclosure will become clearer from the following detailed description in conjunction with the accompanying drawings. Fig. Figure 1 shows an exemplary flowchart illustrating a method for checking a fuel cell stack according to an embodiment of the present invention; Fig. Figure 2 shows an exemplary simplified block diagram for components of a fuel cell stack diagnostic system according to an embodiment of the present invention; Fig. 3A and Fig. Figure 3B shows exemplary flowcharts illustrating a method for checking a fuel cell stack according to an embodiment of the present invention; and Fig. 4A and Fig. Figure 4B shows exemplary flowcharts illustrating a method for checking a fuel cell stack according to a further embodiment of the present invention. DETAILED DESCRIPTION

[0021] It is understood that the term "vehicle" or "vehicle-" or other equivalent expressions as used herein include motor vehicles in general, such as passenger cars including sports utility vehicles (SUVs), buses, trucks, various utility vehicles, watercraft including a variety of boats and ships, aircraft and the like, and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other vehicles using alternative fuels (for example, fuel derived from sources other than petroleum). As referenced herein, a hybrid vehicle is a vehicle that has two or more sources of propulsion, such as both gasoline-powered and electric-powered vehicles.

[0022] Although the embodiment is described as using a plurality of units to perform the exemplary process, it is understood that the exemplary processes can also be performed by one or more modules. Furthermore, it is understood that the term controller / control unit refers to a hardware device comprising memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute said modules to perform one or more processes, which are described below.

[0023] Furthermore, the control logic of the present invention can be implemented as non-volatile, computer-readable media on a computer-readable medium comprising executable program instructions that are executed by a processor, a controller / control unit, or the like. Examples of computer-readable storage media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable recording medium can also be decentralized in networked 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).

[0024] Specific structural or functional descriptions in the embodiments of the present invention, disclosed in this description or application, are provided only to illustrate the embodiments of the present disclosure. These descriptions can be given in various forms and should not be considered limited to the embodiments described in the description or application.

[0025] Certain embodiments are illustrated in the drawings and described in detail in this description or application because the embodiments of the present invention may have various forms and modifications. It is understood, however, that there is no intention to limit the embodiments of the present invention to the specific embodiments shown, but rather that the intention is to cover all modifications, equivalents, and alternatives encompassed within the scope of the present invention.

[0026] Although the terms "first", "second", etc. may be used herein to describe different elements, these elements should not be limited by these terms. These terms are used merely to distinguish one element from another. For example, a first element could be referred to as a second element, and similarly, a second element could be referred to as a first element, without altering the scope of the present invention.

[0027] It is understood that when an element is described as being "coupled" or "connected" to another element, it may be directly coupled or connected to that other element, or there may be intermediate elements. In contrast, when an element is described as being "directly coupled" or "directly connected" to another element, there are no intermediate elements. Other words / expressions used to describe the relationship between elements should be interpreted similarly (for example, "between" versus "directly between," "adjacent / next to" versus "directly adjacent / next to," etc.).

[0028] The terminology used herein is intended for the purpose of describing certain embodiments and is not intended to limit the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It is further understood that the expressions "possess" and / or "possessing," when used in this description, describe the presence of the specified features, numbers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more features, numbers, steps, operations, elements, components, and / or groups thereof. As used herein, the expression "and / or" includes any and all combinations of one or more of the associated listed elements.

[0029] Unless otherwise specified, all terms / expressions used herein (including technical and scientific terms / expressions) have the same meanings as those normally understood by a person skilled in the art in the field to which this invention belongs. It is further understood that terms / expressions such as those defined in commonly used dictionaries should be interpreted in a manner consistent with their meaning in the context of the prior art and not in an idealized or overly formal sense, unless expressly provided herein.

[0030] Reference is now made to the drawings, in which the same reference symbols are used throughout the various drawings to denote the same or similar components.

[0031] Fig. Figure 1 shows an exemplary flowchart illustrating a method for checking a fuel cell stack according to an embodiment of the present invention, and Fig. Figure 2 shows an exemplary simplified block diagram for components of a fuel cell stack diagnostic system according to an embodiment of the present invention. A fuel cell stack diagnostic system 200 according to an embodiment of the present invention may comprise: a fuel cell controller 210, a motor controller 220, and a power conversion controller 230. The fuel cell controller 210 may be configured to communicate with the motor controller 220 and the power conversion controller 230 and may operate the entire fuel cell system. The motor controller 220 may be configured to operate a motor (not shown) using an inverter (not shown). The power conversion controller 230, arranged between a fuel cell stack and a high-voltage battery, may be configured to perform charging and discharging of the high-voltage battery.

[0032] Furthermore, the fuel cell controller 210 can be configured to determine a time when a fuel cell stack check is required based on several factors (S101). These factors may include, but are not limited to, temperature, cell voltage distribution, total voltage, and elapsed operating time of the fuel cell stack. In other words, to determine a time when a fuel cell stack diagnosis is required (e.g., when diagnosis is necessary), the fuel cell controller can be configured to determine a specific time for targeted assessment of whether drying out occurs when certain conditions are met. These conditions can be predetermined according to several factors, including the elapsed operating time of a fuel cell vehicle, the temperature of the fuel cell stack, and so on.

[0033] In particular, the fuel cell controller 210 can be configured to monitor whether a deviation in the fuel cell vehicle's output current is acceptable. In other words, the fuel cell controller 210 can be configured to determine whether the deviation in the fuel cell vehicle's output current is less than a predetermined deviation, because the output current deviation can be determined since there may be an error in the range of a voltage deviation, which is to be measured in a transition section where the output current deviation is substantially high. Additionally, the fuel cell controller 210 can be configured to determine whether the motor controller 220 and power conversion controller 230 are in a normal state.In other words, when the fuel cell controller 210 transmits instructions / commands to the engine controller 220 or the power conversion controller 230, it can be determined whether the engine controller 220 and the power conversion controller 230 can operate according to the instructions by correctly receiving them. In other words, the normal state refers to the controllers operating based on received instructions without any failure or error.

[0034] The fuel cell controller 210 can be configured to initiate a fuel cell stack check in response to a determination that fuel cell stack diagnostics are required, that an output current deviation is less than a specified deviation, and that the motor controller 220 and power conversion controller 230 are in a normal state (S103). In other words, the fuel cell controller 210 can be configured to transmit instructions to the motor controller 220 to initiate the fuel cell stack diagnostics.

[0035] On the other hand, in response to a determination that fuel cell stack diagnostics are not required; a deviation in the output current of the fuel cell stack may be the specified deviation or greater; or the motor control 220 and power conversion control 230 are not in a normal state (for example, are in a fault or failure state), the fuel cell control 210 may be configured to determine whether the fuel cell stack diagnostics are now in progress (S121). In response to a determination that the fuel cell stack diagnostics are in progress, the fuel cell control 210 may be configured to terminate the fuel cell stack diagnostics (S123).

[0036] The motor control 220 can be configured to drive a motor set to an initial efficiency value for a predetermined initial reference period based on the instructions for initiating fuel cell stack diagnostics (S105). Additionally, for a hybrid drive mode, the fuel cell control 210 can be configured to stop the operation of the power conversion control 230 by transmitting instructions to stop its operation. Stopping the operation of the power conversion control 230 can interrupt the current flow between the high-voltage battery and the fuel cell stack through the power conversion control 230, as it may only be necessary to interrupt the current to the fuel cell stack.Furthermore, for a drive mode using a fuel cell, it is not absolutely necessary that the fuel cell controller 210 operates the power conversion controller 230.

[0037] The motor controller 220 can be configured to operate / drive a motor set to a first efficiency value for a predetermined first reference period (S105). When the predetermined first reference period has elapsed, the fuel cell controller 210 can be configured to transmit instructions to the motor controller 220 to terminate the fuel cell stack diagnostics (S107), and the motor controller 220 can be configured to receive the instructions from the fuel cell controller 210 and drive the motor set to a second efficiency value (S109). In particular, the first efficiency value can be lower than the second efficiency value. Driving the motor set to the first efficiency value for the first reference period can intentionally and inefficiently operate the fuel cell stack.The fuel cell controller 210 can be configured to transmit instructions to the engine controller 220 to initiate a fuel cell stack diagnostic. When the predetermined initial reference period has elapsed, the fuel cell controller 210 can be configured to transmit instructions to the engine controller 220 to terminate the fuel cell stack diagnostic.

[0038] The motor's output power while driving a motor set to the first efficiency value can be the same as while driving a motor set to the second efficiency value. The fuel cell controller 210 can be configured to intentionally reduce the motor's drive efficiency, but the motor's output power can be kept essentially constant for sustained driving quality. The second efficiency value can be a normal efficiency value for the motor controller 220. This normal efficiency can be an operating point with maximum efficiency for the motor controller 220 (or the inverter) during operation of the fuel cell stack diagnostic system 200. Furthermore, driving the motor set to the first efficiency value, which may be lower than the second efficiency value, can intentionally reduce the efficiency of the motor controller 220.

[0039] In particular, as the output power of the fuel cell stack increases, the energy consumption of the fuel cell stack can rise, and the voltage of the fuel cell stack can drop significantly. In other words, if the motor is driven at the second efficiency value, which represents a normal efficiency value, after being driven at the first efficiency value for a predetermined initial reference period, the current can be interrupted by as much as the difference between the first and second efficiency values. Consequently, the voltage of the fuel cell stack can rise rapidly, and an ohmic value can be measured using the voltage deviation. When measuring the voltage deviation, the motor controller 220 can be configured to detect an increased voltage gradient and samples the voltage value in units of µs. Therefore, a separate high-speed data analysis device can be omitted.

[0040] The motor control unit 220 can be configured to collect data relating to the voltage deviation before the elapse of the predetermined second reference period by measuring the voltage deviation between driving the motor set to the first efficiency value and the second efficiency value (S111); analyzing an ohmic value based on the collected data (S113); and transmitting the analyzed resistance value to the fuel cell control unit 210. A voltage deviation measurement can be started before the first reference period, during which the motor is driven at the first efficiency value, has elapsed and can be stopped before the second reference period, during which the motor is driven at the second efficiency value, has elapsed.If the voltage deviation measurement is started before the first reference period has elapsed, it may be possible to measure the voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value. The fuel cell controller 210 can further be configured to receive the analyzed resistance value and to check the condition of the fuel cell stack (S115). The fuel cell controller 210 can then be configured to determine whether the fuel cell stack is currently dried out (S117), and if so, to perform a drive to recover from drying out (S119).

[0041] Fig. 3A and Fig. Figure 3B shows exemplary flowcharts illustrating in more detail a method for checking a fuel cell stack according to an embodiment of the present invention. With reference to Fig. 3A and Fig. 3B illustrates the logic in the fuel cell control 210, the logic in the motor control 220 and the power conversion control 230, and the relationships between the controls are made more understandable by the figures. Fig. 3A and Fig. 3B presents a procedure for checking a fuel cell stack for a hybrid vehicle. For a fuel cell vehicle that uses fuel cells as a drive source, a control process relating to the power conversion control 230 can be excluded, and a corresponding flowchart is shown in Fig. 4A and Fig. 4B is shown.

[0042] Considering the logic in the fuel cell control 210, the fuel cell control 210 can be configured to determine whether a fuel cell stack diagnosis is required, whether a deviation of an output current of the fuel cell stack is less than a predetermined deviation, and whether the motor control 220 and the power conversion control 230 are in a normal state (S301).In response to a determination that fuel cell stack diagnostics are required; the deviation of the fuel cell stack output current is less than the specified deviation; and the motor control 220 and the power conversion control 230 are in a normal state, the fuel cell control 210 may be configured to transmit instructions to the motor control 220 to initiate fuel cell stack diagnostics and to transmit instructions to the power conversion control 230 to stop operation of the power conversion control 230 (S303).

[0043] When the first reference period has elapsed (S305), the fuel cell controller 210 can be configured to transmit instructions to the motor controller 220 to terminate the fuel cell stack diagnostics (S307) and to transmit instructions to the power conversion controller 230 to resume operation (S309). Furthermore, the fuel cell controller 210 can be configured to check, based on the analyzed ohmic value received from the motor controller 220, whether the fuel cell stack is in a drying-out state (S311). In response to a determination that the fuel cell stack is drying out, the fuel cell controller 210 can be configured to initiate a drive to recover the fuel cell stack from drying out (S315).

[0044] Furthermore, in response to a determination that fuel cell stack diagnostics are not required; that the fuel cell stack output current deviation may be the specified deviation or greater; or that the motor control 220 and power conversion control 230 are not in a normal state, the fuel cell control 210 may be configured to determine whether fuel cell stack diagnostics are in progress (S317). In response to a determination that fuel cell stack diagnostics are in progress, the fuel cell control 210 may be configured to terminate the fuel cell stack diagnostics (S319).

[0045] Furthermore, considering the logic in the motor controller 220, when the motor controller 220 is in a normal state, the motor controller 220 can be configured to receive instructions from the fuel cell controller 210 to initiate fuel cell stack diagnostics (S321). Upon receiving the instruction to initiate fuel cell stack diagnostics, the motor controller 220 can be configured to drive the motor set to the first efficiency value for the specified first reference period (T1) (S323). After the first reference period has elapsed, the motor controller 220 can be configured to receive instructions to terminate the fuel cell stack diagnostics (S325). Upon receiving the instruction to terminate the fuel cell stack diagnostics, the motor controller 220 can be configured to drive the motor set to the second efficiency value (S327).The motor control unit 220 can further be configured to measure the voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value, and to collect data relating to the voltage deviation (S329). The motor control unit 220 can then be configured to analyze the ohmic value based on the collected data (S331) and to transmit the analyzed resistance value to the fuel cell control unit 210.

[0046] Considering the logic in the power conversion controller 230, the power conversion controller 230 can be configured to receive instructions from the fuel cell controller 210 to stop its operation (S341). Upon receiving the instruction to stop the power conversion controller (off), the power conversion controller can be configured to stop operation. Stopping operation can include interrupting the energy flow from the high-voltage battery. Upon receiving the instructions to resume operation of the power conversion controller (on), the power conversion controller 230 can be configured to resume operation.

Claims

[1] Method for checking a fuel cell stack, comprising: Determine, by means of a control system, a point in time at which a check of a fuel cell stack is required, based on several factors; Stopping, by control, an operation of a power conversion control (230) which stops a charging and discharging of a high voltage battery between the high voltage battery and the fuel cell stack; Driving, by means of the control, a motor set to an initial efficiency value during a predetermined initial reference period from the time of the diagnostic determination; Driving, by means of the control system, the motor set to a second efficiency value after the first reference period has elapsed; and Checking, by means of the control, a state of the fuel cell stack based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and second efficiency value. [2] Method according to claim 1, further comprising: Determine, through control, whether a deviation of an output current of the fuel cell stack is smaller than a predetermined deviation. [3] Method according to claim 1, wherein the first efficiency value is smaller than the second efficiency value. [4] Method according to claim 1, wherein the motor output power in driving the motor set to the first efficiency value is the same as in driving the motor set to the second efficiency value. [5] Method according to claim 1, further comprising: Collecting, through control, data relating to a voltage deviation by measuring a voltage deviation during a predetermined second reference period; and Verification, through control, of a state of the fuel cell stack by analyzing a resistance value based on the collected data. [6] Method according to claim 1, further comprising: Resume operation of the power conversion control (230) by means of the control when the diagnosis is complete. [7] Method for checking a fuel cell stack, comprising: Determine, by means of a control system, whether a deviation of an output current of the fuel cell stack is less than a predetermined deviation, whether a check of the fuel cell stack is required, and whether a motor control (220) and power conversion control (230) are in a normal state; The instructions of the motor control (220) are transmitted by the control unit to initiate a diagnosis of the fuel cell stack based on a result of the diagnostic determination and to stop operation of the power conversion control (230), wherein the instruction to drive a motor set to a first efficiency value for a predetermined first reference period is provided; when the specified first reference period has elapsed, the control unit transmits instructions to the motor control unit (220) to terminate a diagnosis of the fuel cell stack, to drive the motor set to a second efficiency value, and to resume operation of the power conversion control unit (230); and Checking, by means of the control, a state of the fuel cell stack based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and second efficiency value. [8] System for checking a fuel cell stack, comprising: a fuel cell controller (210) configured to check the state of the fuel cell stack by determining a time at which a fuel cell stack check is required based on several factors; a motor control unit (220) configured to drive a motor set to a first efficiency value for a predetermined first reference period based on a diagnostic determination, to drive the motor set to a second efficiency value when the first reference period has elapsed, and to transmit to the fuel cell control unit (210) a resistance value analyzed on the basis of a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value; and a power conversion controller (230) which is set up to regulate the charging and discharging of a high-voltage battery between the high-voltage battery and the fuel cell stack, wherein the fuel cell control (210) is configured to determine whether the power conversion control (230) and the engine control (220) are in a normal state, and wherein the fuel cell control (210) is set up to check the state of the fuel cell based on the transmitted resistance value. [9] System according to claim 8, wherein the fuel cell control (210) is configured to determine whether a deviation of an output current of the fuel cell stack is less than a predetermined deviation. [10] System according to claim 8, wherein the fuel cell controller (210) is configured to operate the motor controller (220) to drive the motor set to a first efficiency value when a check of the fuel cell stack is required and the deviation of the output current is less than the predetermined deviation. [11] System according to claim 8, wherein the fuel cell control (210) is configured to stop operation of the power conversion control (230) and motor control (220) in response to a determination that the power conversion control (230) and motor control (220) are in the normal state and to operate the motor control (220) to drive the motor set to the first efficiency value. [12] System according to claim 8, wherein the first efficiency value is smaller than the second efficiency value. [13] System according to claim 8, wherein the motor output power when driving the motor set to the first efficiency value is the same as when driving the motor set to the second efficiency value. [14] System according to claim 11, wherein the fuel cell control (210) is configured to resume operation of the power conversion control (230) when the diagnosis is complete. [15] Non-volatile computer-readable medium containing program instructions that are executed by a controller, comprising the computer-readable medium: Program instructions that determine a time when a fuel cell stack needs to be checked based on a plurality of factors; Program commands that stop the operation of a power conversion controller (230) that regulates the charging and discharging of a high-voltage battery between the high-voltage battery and the fuel cell stack; Program commands that drive a motor set to a first efficiency value for a predetermined first reference period from the time of diagnosis; Program commands that drive the motor set to a second efficiency value after the first reference period has elapsed; and Program commands that check the state of the fuel cell stack based on a voltage deviation of the fuel cell stack between driving the motor set to the first efficiency value and the second efficiency value. [16] Non-volatile computer-readable medium according to claim 15, further comprising: Program commands that determine whether a deviation of an output current of the fuel cell stack is smaller than a specified deviation. [17] Non-volatile computer-readable medium according to claim 15, wherein the first efficiency value is smaller than the second efficiency value. [18] Non-volatile computer-readable medium according to claim 15, wherein the motor output power in driving the motor set to the first efficiency value is the same as in driving the motor set to the second efficiency value.

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