Apparatus and method for compensating offset of pressure sensor in feul cell system

Abstract

A pressure sensor offset correction device for a fuel cell system comprising a first pressure sensor and a second pressure sensor installed between the downstream end of a fuel supply valve of a hydrogen supply system and the anode inlet is introduced, comprising an offset corrector that calculates an offset between the sensors from the dynamic pressure conditions of each sensor and corrects the offset for the first pressure sensor and the second pressure sensor using the calculated offsets, and an offset correction method using the same is introduced.

Description

Technology Field

[0001] The present invention relates to a pressure sensor offset correction technology in a fuel cell system, and more specifically, to a pressure sensor offset correction device and method in a fuel cell system capable of correcting the difference between the measured value and the actual pressure in a pressure sensor used in a fuel cell system. Background Technology

[0003] A fuel cell is an energy conversion device that converts the chemical energy contained in fuel into electrical energy through an electrochemical reaction without converting it into heat through combustion. It can be used not only to supply power for industrial, residential, and automotive use, but also to power small electrical and electronic products and portable devices.

[0004] In particular, in Polymer Electrolyte Membrane Fuel Cells (PEMFCs) with high power density, the Membrane-Electrode Assembly (MEA), which is the main component, is located at the innermost part. The MEA consists of a solid polymer electrolyte membrane capable of transporting hydrogen ions, and cathodes and anodes, which are electrode layers coated with catalysts on both sides of the electrolyte membrane to allow hydrogen and oxygen to react.

[0005] In the hydrogen supply system, high-pressure hydrogen supplied from the hydrogen tank is depressurized to a constant pressure before being supplied to the fuel cell stack. At this stage, the amount of depressurized hydrogen supplied to the fuel cell stack is controlled through pressure control according to the operating conditions of the fuel cell stack. Additionally, any hydrogen remaining after the reaction in the fuel cell stack is recirculated to the anode by a hydrogen recirculation device.

[0006] In a conventional fuel cell system, valves are installed in the hydrogen supply system to cut off the hydrogen supply, and pressure sensors are installed near these valves to measure the pressure in the hydrogen supply system.

[0007] Currently, fuel cell systems are controlled using measurements from these pressure sensors, and the accuracy of these measurements significantly affects the system's fuel efficiency and durability.

[0008] Meanwhile, as these pressure sensors gradually develop an offset as the fuel cell system operates, it is required to ensure the accuracy of the pressure sensor measurements by correcting this offset. In addition, when using gauge pressure sensors that cannot measure pressures below atmospheric pressure, there was a problem in that offset correction was impossible because the existing method could not correct negative (-) offsets. Prior art literature

[0010] (Patent Document 0001) KR 10-2018-0114585 A The problem to be solved

[0011] The present invention is proposed to solve these problems and aims to provide a pressure sensor offset correction device and method in a fuel cell system that can improve the accuracy of pressure sensor measurements by correcting the offset of the pressure sensor in the hydrogen supply system of the fuel cell system.

[0012] In particular, the present invention aims to enable offset correction even for nozzle pressure sensors configured not to measure pressures below atmospheric pressure, such as gauge pressure sensors, by calculating and summing the negative (-) offset and the positive (+) offset respectively. means of solving the problem

[0014] A method for correcting a pressure sensor offset in a fuel cell system according to the present invention for achieving the above-mentioned purpose comprises a first pressure sensor and a second pressure sensor installed between the downstream end of a fuel supply valve of a hydrogen supply system and an anode inlet, wherein, in a closed state of the fuel supply valve, the method comprises: a step of determining whether the pressure at the position of the first pressure sensor (S1) and the pressure at the position of the second pressure sensor (S2) are the same pressure; a step of calculating a first offset from the difference between the detected pressure of the first pressure sensor and the detected pressure of the second pressure sensor when determined to be the same pressure; and a step of determining whether the pressure at the position of the second pressure sensor (S2) is the same pressure as atmospheric pressure by opening the fuel discharge valve. When the pressure at the location of the second pressure sensor (S2) is determined to be the same pressure as the atmospheric pressure, the method includes the step of calculating a second offset from the difference between the pressure detected by the atmospheric pressure sensor and the pressure detected by the second pressure sensor (S2) while the fuel discharge valve is closed; and the step of correcting the offset between the first pressure sensor (S1) and the second pressure sensor (S2) using the first offset and the second offset.

[0015] In the step of correcting the offset of the first pressure sensor (S1) and the second pressure sensor (S2), the offset for the first pressure sensor is determined as the sum of the first offset and the second offset, and the offset for the second pressure sensor can be determined as the second offset.

[0016] In the above S1-S2 dynamic pressure determination step, dynamic pressure can be determined when a preset first reference time elapses, or when the amount of change in the pressure detected by the first pressure sensor and the amount of change in the pressure detected by the second pressure sensor are each maintained below a preset threshold change amount for a second reference time.

[0017] In the above S2-atmosphere pressure dynamic pressure determination step, dynamic pressure can be determined when the gas discharge amount of the hydrogen supply system reaches a preset reference value, or when the change amount of the pressure detected by the atmospheric pressure sensor and the change amount of the pressure detected by the second pressure sensor are each maintained below a preset threshold change amount for a second reference time.

[0018] Prior to the above S1-S2 dynamic pressure determination step, the offset corrector may further include a step of checking whether the first sensor correction period (T1) or the second sensor correction period (T2) has been reached.

[0019] When the first sensor correction period (T1) is reached, the offset of the first pressure sensor can be corrected by the sum of the first offset and the second offset calculated by performing the steps below the S1-S2 dynamic pressure judgment step.

[0020] When the second sensor correction period (T2) is reached, the first offset calculation step is omitted, and only the steps below the S2-atmosphere pressure dynamic pressure determination step are performed, and the offset of the second pressure sensor can be corrected by the calculated second offset.

[0021] In addition, the present invention relates to a pressure sensor offset correction device in a fuel cell system comprising a first pressure sensor and a second pressure sensor installed between the downstream end of a fuel supply valve of a hydrogen supply system and an anode inlet, wherein the device comprises an offset corrector that corrects the offset for the first pressure sensor and the offset for the second pressure sensor, and the offset corrector comprises:

[0022] The present invention provides a pressure sensor offset correction device for a fuel cell system configured to calculate a first offset from the difference between the detected pressure of the first pressure sensor and the detected pressure of the second pressure sensor when the pressure at the location of the first pressure sensor (S1) and the pressure at the location of the second pressure sensor (S2) are equal pressure when the fuel supply valve is closed, and to calculate a second offset from the difference between the detected pressure of the atmospheric pressure sensor and the detected pressure of the second pressure sensor (S2) when the fuel discharge valve connected to the exhaust side is opened and the pressure at the location of the second pressure sensor (S2) is equal to atmospheric pressure, and to calculate a second offset from the difference between the detected pressure of the atmospheric pressure sensor and the detected pressure of the second pressure sensor (S2) when the fuel discharge valve is closed, and the offset corrector is configured to correct the offset between the first pressure sensor (S1) and the second pressure sensor (S2) using the calculated first offset and the second offset.

[0023] The above offset corrector determines the sum of the first offset and the second offset as the offset for the first pressure sensor, and the second offset can be determined as the offset for the second pressure sensor.

[0024] The offset corrector stores information regarding the first sensor correction period (T1) for the first pressure sensor and the second sensor correction period (T2) for the second pressure sensor, and the offset corrector checks whether the first sensor correction period (T1) or the second sensor correction period (T2) has been reached. If the first sensor correction period (T1) has been reached, the offset of the first pressure sensor is corrected by the sum of the calculated first offset and the second offset. If the second sensor correction period (T2) has been reached, the offset of the second pressure sensor is corrected by the calculated second offset.

[0025] The first pressure sensor may be a gauge pressure sensor, and the second pressure sensor may be an absolute pressure sensor; in particular, the first pressure sensor may be a nozzle pressure sensor located between the fuel supply valve and the ejector, and the second pressure sensor may be an anode pressure sensor located between the rear end of the ejector and the anode inlet. Effects of the invention

[0027] According to the pressure sensor offset correction device and method of the fuel cell system of the present invention, by setting dynamic pressure conditions between pressure sensors by considering changes in pressure conditions due to the opening and closing of valves within the fuel cell system, there is an advantage in that the offset value can be accurately calculated solely from the difference in measured values ​​between pressure sensors. Therefore, according to the pressure sensor offset correction device and method of the fuel cell system of the present invention, the offset correction of the hydrogen supply system pressure sensor can be performed simply without adding separate hardware.

[0028] In addition, according to the present invention, even if the nozzle pressure sensor is configured to be a sensor capable of measuring only pressures above atmospheric pressure, the nozzle pressure sensor has the effect of enabling offset correction by calculating and summing the negative (-) offset and the positive (+) offset, respectively.

[0029] In addition, according to the present invention, since the offset of the nozzle pressure sensor and the anode pressure sensor of the hydrogen supply system can be accurately corrected, the accuracy of the measurements of each sensor is improved, thereby enhancing the stack durability of the fuel cell system and improving fuel efficiency. Brief explanation of the drawing

[0031] FIG. 1 is a configuration diagram of a fuel cell system to which a pressure sensor offset correction device according to one embodiment of the present invention is applied. Figure 2 is a graph conceptually showing the pressure measurement range according to the type of pressure sensor. Figure 3 is a graph illustrating the offset correction process of the anode pressure sensor. FIG. 4 is a flowchart conceptually showing each step of a pressure sensor offset correction method of a fuel cell system according to an embodiment of the present invention. FIG. 5 is a flowchart showing detailed steps of a pressure sensor offset correction method for a fuel cell system according to an embodiment of the present invention. FIG. 6 is a graph showing the process of correcting the offset of a nozzle pressure sensor in a pressure sensor offset correction method of a fuel cell system according to an embodiment of the present invention. Specific details for implementing the invention

[0032] Hereinafter, a pressure sensor offset correction device and method for a fuel cell system according to various embodiments of the present invention will be described in detail with reference to the attached drawings.

[0033] FIG. 1 is a configuration diagram of a fuel cell system to which a pressure sensor offset correction device according to one embodiment of the present invention is applied, and FIG. 2 is a graph conceptually showing the pressure measurement range according to the type of pressure sensor.

[0034] Referring to FIG. 1, a hydrogen supply system for supplying hydrogen is connected to the anode (11) of the fuel cell stack (10), and an air supply system for supplying air is connected to the cathode (12).

[0035] The above air supply system inhales external air, compresses and humidifies it, and supplies it to the cathode (12). At this time, the air passing through the cathode (12) reacts with hydrogen on the anode (11) side to produce electricity.

[0036] In the above hydrogen supply system, a hydrogen source (a pressure vessel in which hydrogen is stored) is installed, and an ejector is installed to inject air supplied from this hydrogen source toward the anode (11). Additionally, a fuel shut-off valve (V1) is installed in the hydrogen supply system to block fuel supplied from the hydrogen source toward the ejector, and a fuel supply valve (V2) can be installed downstream therefrom to regulate the hydrogen pressure supplied to the fuel cell stack. This fuel supply valve (V2) can be configured to reduce the high-pressure gas stored in the pressure vessel to a constant pressure. Accordingly, hydrogen supplied from the hydrogen source is supplied toward the anode (11) through the ejector when the fuel shut-off valve (V1) and the fuel supply valve (V2) are opened.

[0037] Some of the hydrogen supplied to the anode (11) that does not participate in the reaction can be recirculated to the front end of the anode (11) and supplied back to the anode (11). At this time, condensate inside the anode (11) is discharged together with the hydrogen that did not participate in the reaction, and a water trap is installed on the anode outlet side to collect this condensate.

[0038] A water level sensor is installed in the water trap (14) to detect the water level inside the water trap, and if the water level of the condensate is confirmed to be above a critical threshold through the water level sensor, it can be discharged to the outside through the fuel discharge valve (V3) at the bottom of the water trap (14). In this case, not only the condensate but also gases such as hydrogen from the anode outlet can be discharged through the fuel discharge valve (V3).

[0039] Meanwhile, pressure sensors for detecting pressure may be installed at the front and rear ends of such ejectors. Specifically, as shown in FIG. 1, a nozzle pressure sensor may be installed as a first pressure sensor (S1) between the fuel supply valve (V2) and the ejector, and an anode pressure sensor may be installed as a second pressure sensor (S2) at the rear end of the ejector and the front end of the anode inlet.

[0040] The amount of off-gas discharged through the fuel discharge valve (V3), i.e., the amount of gas discharged from the anode, can be estimated using a nozzle pressure sensor, and this can be used to calculate the anode hydrogen concentration and determine the closing time of the fuel discharge valve (V3). In addition, the anode pressure sensor can be used to determine the amount of hydrogen supplied through pressure proportional-integral (PI) control.

[0041] In addition, the nozzle pressure sensor may be configured as a gauge sensor capable of measuring only positive (+) pressure relative to atmospheric pressure, and the anode pressure sensor may be configured as an absolute pressure sensor capable of measuring pressures below atmospheric pressure.

[0042] In this regard, Figure 2 illustrates the measurable range according to the type of pressure sensor. As shown in Figure 2, the nozzle pressure sensor has a limitation in that it cannot measure pressures below atmospheric pressure because it is composed of a gauge pressure sensor, whereas the anode pressure sensor can measure pressures across the entire range including positive (+) and negative (-) pressures relative to atmospheric pressure because it is composed of an absolute pressure sensor.

[0043] A pressure sensor offset correction device of a fuel cell system according to a preferred embodiment of the present invention is configured to enable offset correction of the pressure sensor by an offset corrector (20), even if it includes both types of sensors.

[0044] In this regard, FIG. 3 introduces a method for correcting the offset of the anode pressure sensor (S2) from the difference between the measured values ​​of the atmospheric pressure sensor and the anode pressure sensor, that is, the actual measured pressure value. That is, as shown in FIG. 3, when the fuel cell system is stopped and the hydrogen supply valve (fuel supply valve) is closed, and the fuel discharge valve (V3) is opened, the anode side is exhausted and becomes an atmospheric pressure state. Accordingly, the measured value of the anode pressure sensor gradually decreases and drops to near atmospheric pressure.

[0045] At this time, if the pressure of the hydrogen supply system, that is, the pressure at the location of the anode pressure sensor (S2), is determined to be equal to the atmospheric pressure, the difference between the measured value of the atmospheric pressure sensor and the measured value of the anode pressure sensor at that time ultimately becomes the offset of the anode pressure sensor. Therefore, offset correction is possible by applying the calculated offset value to the anode pressure sensor.

[0046] However, since negative offset correction is impossible with this type of offset correction for nozzle pressure sensors that cannot measure pressures below atmospheric pressure, it is difficult to apply the offset correction method of the anode pressure sensor as is.

[0047] Meanwhile, the present invention is characterized by including an offset corrector (20) for correcting pressure sensors of a hydrogen supply system, wherein the offset corrector (20) can calculate a first offset based on the difference in measured values ​​between a nozzle pressure sensor and an anode pressure sensor and a second offset based on the difference in measured values ​​between an atmospheric pressure sensor and an anode pressure sensor, and the offset correction of the nozzle pressure sensor and the anode pressure sensor is possible based on the first offset and the second offset.

[0048] As illustrated in FIG. 1, the offset corrector is connected to a first pressure sensor (S1) and a second pressure sensor (S2), is configured to receive the measured values ​​of each pressure sensor, and is configured to perform offset correction for each pressure sensor. Additionally, the offset corrector is connected to a fuel shut-off valve (V1), a fuel supply valve (V2), and a fuel discharge valve (V3) and is configured to receive information regarding the open / closed state of each valve. Furthermore, the offset corrector may be configured as part of a controller for controlling each component within a fuel cell system, and may be configured to replace the controller to perform open / close control of each valve, limited to system shutdown and offset correction control.

[0049] Hereinafter, in describing the offset corrector (20) in the present invention, the nozzle pressure sensor is described as the first pressure sensor (S1), and the anode pressure sensor is described as the second pressure sensor (S2).

[0050] The offset corrector (20) may be configured to determine whether the pressure at the position of the first pressure sensor (S1) and the pressure at the position of the second pressure sensor (S2) are equal pressure when the fuel supply valve (V2) is in a closed state, and if it is determined that they are equal pressure, to calculate a first offset from the difference between the detected pressure of the first pressure sensor (S1) and the detected pressure of the second pressure sensor (S2).

[0051] In this regard, since the actual pressure at the location of the first pressure sensor (S1) and the actual pressure at the location of the second pressure sensor (S2) are in a dynamic pressure state, the difference between the measured value of the first pressure sensor (S1) and the measured value of the second pressure sensor (S2) represents the offset between the two sensors.

[0052] Similarly, by bringing the second pressure sensor and the atmospheric pressure sensor to a state of dynamic pressure through valve control, and then detecting the difference in measurement between the second pressure sensor and the atmospheric pressure sensor, that difference in measurement represents the offset between the second pressure sensor and the atmospheric pressure.

[0053] Therefore, in detecting the offset between the second pressure sensor and atmospheric pressure, the following offset determination method can be applied.

[0054] That is, with the fuel supply valve (V2) closed, the fuel discharge valve (V3) connected to the exhaust side is opened to determine whether the pressure at the location of the second pressure sensor (S2) is equal to atmospheric pressure. At this time, if the pressure at the location of the second pressure sensor (S2) is equal to atmospheric pressure, the second offset can be calculated from the difference between the pressure detected by the atmospheric pressure sensor and the pressure detected by the second pressure sensor (S2) while the fuel discharge valve (V3) is closed.

[0055] At this time, the offset for the first pressure sensor (S1) is determined by the sum of the first offset and the second offset, and the offset for the second pressure sensor (S2) is determined by the second offset.

[0056] Meanwhile, the offset corrector (20) can store information regarding the first sensor correction period (T1) for the first pressure sensor (S1) and the second sensor correction period (T2) for the second pressure sensor (S2). Accordingly, the offset corrector (20) can selectively perform correction for each pressure sensor by checking whether the stored first sensor correction period (T1) or second sensor correction period (T2) has been reached.

[0057] For example, when the first sensor correction period (T1) is reached, the offset corrector (20) can correct the offset of the first pressure sensor (S1) by the sum of the calculated first offset and the second offset. On the other hand, when the second sensor correction period (T2) is reached, the offset corrector (20) can correct the offset of the second pressure sensor (S2) by the calculated second offset.

[0058] A method for correcting the offset of a pressure sensor in a fuel cell system according to a preferred embodiment of the present invention, which can be implemented using the pressure sensor offset correction device of the fuel cell system as described above, is illustrated in FIG. 4. In particular, FIG. 4 is a flowchart conceptually showing each step of the pressure sensor offset correction method according to the present invention.

[0059] Referring to FIG. 4, in the pressure sensor offset correction method of the fuel cell system according to the present invention, the fuel supply valve (V2) is closed (S401), and the offset correction period of the first pressure sensor (S1) and the second pressure sensor (S2) is determined (S402).

[0060] Afterward, a step (S403) is performed to check whether the pressure at each location of the first and second pressure sensors (S1, S2) is dynamic pressure after closing the fuel supply valve (V2), and to calculate a first offset (offset1) from the difference between the measured values ​​of the first and second pressure sensors. Afterward, the fuel discharge valve (V3) is opened (S404), and a step (S405) is performed to check whether the pressure of the hydrogen supply system is dynamic pressure with atmospheric pressure. Afterward, after closing the fuel discharge valve (V3), a second offset (offset2) is calculated from the difference between the measured values ​​of the second pressure sensor (S2) and the atmospheric pressure sensor (S406), and finally, offset correction for the pressure sensors is possible using the first offset and the second offset (S407).

[0061] Next, FIG. 5 illustrates in more detail a method for correcting the offset of a pressure sensor of a fuel cell system according to one embodiment of the present invention, and FIG. 6 shows the process of correcting the offset of a nozzle pressure sensor accordingly.

[0062] Referring to FIG. 5, the pressure sensor offset correction method of a fuel cell system according to the present invention is performed during the shutdown of the fuel cell system, starting from the closing of the fuel supply valve for system shutdown, and when the correction of the pressure sensor is completed, the system shutdown can finally be completed (S512).

[0063] Specifically, in the closed state (S501) of the fuel supply valve (V2), the offset corrector (20) can check whether the sensor correction cycle has been reached (S502). If, as a result of the check, it is determined that the sensor correction cycle has not arrived, the steps related to offset correction are not performed, and the system stop is completed immediately (S512).

[0064] Meanwhile, the sensor correction cycles T1 and T2 for the two sensors subject to offset correction, namely the first pressure sensor (nozzle pressure sensor; S1) and the second pressure sensor (anode pressure sensor; S2) of the hydrogen supply system, can be pre-stored in the offset corrector (20).

[0065] For example, since the correction period (T1) of the first pressure sensor (S1), which is a gauge pressure sensor, has a larger value than the correction period (T2) of the second pressure sensor, which is an absolute pressure sensor, the time required for system shutdown can be shortened by applying different steps according to the correction period of each pressure sensor. These steps for each correction period will be explained in more detail later.

[0066] When the sensor calibration cycle arrives, an S1-S2 simultaneous pressure determination step (S503) is performed to determine whether the pressure at the location of the first pressure sensor (S1) and the pressure at the location of the second pressure sensor (S2) are simultaneous pressures. If it is determined to be simultaneous pressure through the above step S503, a first offset (P) is determined from the difference between the detected pressure of the first pressure sensor (S1) and the detected pressure of the second pressure sensor (S2). offset1 ) will be produced (S504).

[0067] Next, the fuel discharge valve (V3) is opened (S505), and a step S2-atmosphere pressure equilibrium determination step (S506) is performed to determine whether the pressure at the location of the second pressure sensor (S2) is equal to atmospheric pressure. If, through step S506, the pressure at the location of the second pressure sensor (S2) is determined to be equal to atmospheric pressure, a second offset (P) is determined from the difference between the pressure detected by the atmospheric pressure sensor and the pressure detected by the second pressure sensor (S2) while the fuel discharge valve (V3) is closed (S507). offset2 ) is calculated (S508). The first offset (P offset1 ) and the second offset (P offset2If ) is calculated, the offsets of the first pressure sensor (S1) and the second pressure sensor (S2) can be calculated respectively using the two values ​​above. At this time, the offset for the first pressure sensor (S1) is determined as the sum of the first offset and the second offset, and the offset for the second pressure sensor can be determined as the second offset (S509).

[0068] On the other hand, if it is determined in step S503 that the pressure is not dynamic, the correction failure history can be saved (S511) or used as a hydrogen supply system fault diagnosis condition. Additionally, if it is determined in step S506 that the pressure is not dynamic, the fuel discharge valve (V3) is closed (S510) to prevent excessive hydrogen discharge. Additionally, if the pressure condition is not achieved in step S506, the correction failure history can be saved (S511) and used for the next correction or applied as a hydrogen supply system fault diagnosis condition.

[0069] Meanwhile, referring to FIG. 5, the dynamic pressure determination step in steps S503 and S506 is performed in the present invention. In this regard, in the S1-S2 dynamic pressure determination step (S503), a constant first reference time set through testing may be elapsed to determine dynamic pressure. This first reference time may be a value determined from experimentally obtained data regarding the time required for the pressure at the S1 and S2 sensor locations to reach a substantially dynamic pressure state after the fuel supply valve is closed.

[0070] Additionally, in the S1-S2 dynamic pressure determination step (S503), dynamic pressure can be determined if the amount of change in the detected pressure of the first pressure sensor (S1) and the amount of change in the detected pressure of the second pressure sensor (S2) are each maintained below a preset threshold change amount for a certain second reference time. In this regard, the threshold change amount and the second reference time are preset values ​​to determine that the dynamic pressure condition is satisfied, meaning that the change in the detected pressure must continue below a certain level for a minimum required time.

[0071] In addition, in the above S2-atmosphere pressure dynamic pressure determination step, if the gas discharge amount of the hydrogen supply system reaches a preset reference value, or if the change amount of the pressure detected by the atmospheric pressure sensor and the change amount of the pressure detected by the second pressure sensor are each maintained below a preset threshold change amount for a second reference time, the pressure at the location of the second pressure sensor and the atmospheric pressure can be determined as dynamic pressure. Although the threshold change amount and the second reference time are exemplified as being set to the same values ​​as the preceding S1-S2 dynamic pressure determination conditions, the present invention is not limited to having only the same threshold change amount and second reference time, and the above values ​​can be appropriately changed within a range where the dynamic pressure state can be accurately confirmed.

[0072] In addition, when determining the sensor correction period in step S502, if the correction period (T1) of the first pressure sensor has arrived, the first pressure sensor (S1) can be corrected by performing all steps S503 through S512. On the other hand, if it is determined in step S502 that the correction period (T2) of the second pressure sensor (S2) has arrived, steps S503 through S504 are omitted, and it is sufficient to calculate only the second offset by performing only the steps S505 and below. At this time, the calculated second offset can be applied as a correction value for the second pressure sensor (S2).

[0073] Figure 6 is a graph showing the process of correcting the offset of the nozzle pressure sensor through the pressure sensor offset correction method of the fuel cell system as shown in Figure 5.

[0074] As shown in FIG. 6, when the system stops, the fuel supply valve (V2) is closed, and then, as indicated by '①', it is determined whether the change amount of the first pressure sensor (S1) and the second pressure sensor (S2) is maintained at a level below a certain level for a certain period of time, and if the condition is satisfied, the difference between the measurement of the second pressure sensor (S2) and the measurement of the first pressure sensor (S1) can be set as the first offset.

[0075] Afterwards, the fuel discharge valve (V3) is switched to an open state, and accordingly, the pressure on the anode side drops to the level of atmospheric pressure. As indicated in the box of '②', if the change amount of the measurement value of the second pressure sensor (S2) is maintained at a level below a certain level for a certain period of time, the fuel discharge valve (V3) is closed again, and then the second offset is calculated from the difference between the measurement values ​​of the atmospheric pressure sensor and the second pressure sensor (S2).

[0076] The bottom of the graph in Fig. 6 shows the first offset and the second offset. As in ③, the offset of the first pressure sensor (S1) is processed as the sum of the first offset and the second offset, and the offset of the second pressure sensor (S2) is processed as the second offset.

[0077] Although specific embodiments of the present invention have been illustrated and described, it will be obvious to those skilled in the art that the present invention can be modified and changed in various ways without departing from the technical spirit of the invention as provided by the following claims. Explanation of the symbols

[0079] 10: Fuel cell stack 11: Anode 12: Cathode 13: Ejector 14: Water trap 20: Offset corrector V1: Fuel shut-off valve V2: Fuel supply valve V3: Fuel drain valve S1: First pressure sensor S2: Second pressure sensor

Claims

Claim 1 A method for correcting pressure sensor offsets in a fuel cell system comprising a first pressure sensor and a second pressure sensor installed between the downstream end of a fuel supply valve of a hydrogen supply system and an anode inlet, comprising: a S1-S2 equilibrium pressure determination step for determining whether the pressure at the location of the first pressure sensor (S1) and the pressure at the location of the second pressure sensor (S2) are equilibrium pressures when the fuel supply valve is in a closed state; a step of calculating a first offset from the difference between the detected pressure of the first pressure sensor and the detected pressure of the second pressure sensor when it is determined to be equilibrium pressures; a S2-atmosphere pressure equilibrium pressure determination step for determining whether the pressure at the location of the second pressure sensor (S2) is equilibrium pressures with atmospheric pressure by opening the fuel discharge valve; a step of calculating a second offset from the difference between the detected pressure of the atmospheric pressure sensor and the detected pressure of the second pressure sensor (S2) when the pressure at the location of the second pressure sensor (S2) is determined to be equilibrium pressures with atmospheric pressure when the fuel discharge valve is closed; and the first offset and A method for correcting pressure sensor offsets of a fuel cell system, comprising the step of correcting the offset between the first pressure sensor (S1) and the second pressure sensor (S2) using the second offset. Claim 2 A method for correcting pressure sensor offsets of a fuel cell system according to claim 1, wherein in the step of correcting the offsets of the first pressure sensor (S1) and the second pressure sensor (S2), the offset for the first pressure sensor is determined as the sum of the first offset and the second offset, and the offset for the second pressure sensor is determined as the second offset. Claim 3 A method for correcting a pressure sensor offset of a fuel cell system according to claim 1, wherein in the S1-S2 dynamic pressure determination step, the dynamic pressure is determined after a preset first reference time has elapsed. Claim 4 A method for correcting pressure sensor offset of a fuel cell system according to claim 1, wherein in the S1-S2 dynamic pressure determination step, the change amount of the pressure detected by the first pressure sensor and the change amount of the pressure detected by the second pressure sensor are each maintained below a preset threshold change amount for a second reference time, thereby determining it as dynamic pressure. Claim 5 A method for correcting a pressure sensor offset of a fuel cell system according to claim 1, wherein in the S2-atmosphere pressure dynamic pressure determination step, the pressure is determined to be dynamic pressure when the gas discharge amount of the hydrogen supply system reaches a preset reference value. Claim 6 A method for correcting pressure sensor offset of a fuel cell system according to claim 1, wherein in the S2-atmosphere pressure dynamic pressure determination step, the change amount of the pressure detected by the atmospheric pressure sensor and the change amount of the pressure detected by the second pressure sensor are each maintained below a preset threshold change amount for a second reference time, thereby determining it as dynamic pressure. Claim 7 A method for correcting pressure sensor offsets of a fuel cell system according to claim 1, wherein a first sensor correction period (T1) for the first pressure sensor and a second sensor correction period (T2) for the second pressure sensor are predetermined and stored in an offset corrector, and prior to the S1-S2 dynamic pressure determination step, the offset corrector checks whether the first sensor correction period (T1) or the second sensor correction period (T2) has been reached. Claim 8 A method for correcting the offset of a pressure sensor in a fuel cell system according to claim 7, characterized in that when the first sensor correction period (T1) is reached, the offset of the first pressure sensor is corrected by the sum of the first offset and the second offset calculated by performing the steps below the S1-S2 dynamic pressure judgment step. Claim 9 A method for correcting the offset of a pressure sensor in a fuel cell system according to claim 7, wherein when the second sensor correction period (T2) is reached, the first offset calculation step is omitted, only the steps below the S2-atmosphere pressure dynamic pressure determination step are performed, and the offset of the second pressure sensor is corrected by the calculated second offset. Claim 10 A pressure sensor offset correction device in a fuel cell system comprising a first pressure sensor and a second pressure sensor installed between the downstream end of a fuel supply valve of a hydrogen supply system and an anode inlet, the device comprising an offset corrector that corrects the offset for the first pressure sensor and the offset for the second pressure sensor, wherein the offset corrector is configured to calculate a first offset from the difference between the detected pressure of the first pressure sensor and the detected pressure of the second pressure sensor when the pressure at the location of the first pressure sensor (S1) and the pressure at the location of the second pressure sensor (S2) are equal pressure when the fuel supply valve is closed, and wherein the fuel discharge valve connected to the exhaust side is opened so that the pressure at the location of the second pressure sensor (S2) is equal pressure with atmospheric pressure when the fuel discharge valve is closed, thereby calculating a second offset from the difference between the detected pressure of the atmospheric pressure sensor and the detected pressure of the second pressure sensor (S2). The offset corrector calculates the first offset and the Pressure sensor offset correction device of a fuel cell system configured to correct the offset of the first pressure sensor (S1) and the second pressure sensor (S2) using a second offset. Claim 11 A pressure sensor offset correction device of a fuel cell system according to claim 10, wherein the offset corrector determines the sum of the first offset and the second offset as the offset for the first pressure sensor, and determines the second offset as the offset for the second pressure sensor. Claim 12 A pressure sensor offset correction device of a fuel cell system according to claim 10, wherein the offset corrector determines that the pressure at the position of the first pressure sensor (S1) and the pressure at the position of the second pressure sensor (S2) are equal pressures when a first reference time, which is preset in the closed state of the fuel supply valve, has elapsed. Claim 13 A pressure sensor offset correction device of a fuel cell system according to claim 10, wherein the offset corrector determines that the pressure at the position of the first pressure sensor (S1) and the pressure at the position of the second pressure sensor (S2) are the same pressure when the amount of change in the detected pressure of the first pressure sensor and the amount of change in the detected pressure of the second pressure sensor are each maintained below a preset threshold change amount for a second reference time. Claim 14 A pressure sensor offset correction device of a fuel cell system according to claim 10, wherein the offset corrector determines that the pressure at the location of the second pressure sensor (S2) is the same pressure as atmospheric pressure when the gas discharge amount of the hydrogen supply system reaches a preset reference value after the fuel discharge valve is opened. Claim 15 A pressure sensor offset correction device of a fuel cell system according to claim 10, wherein the offset corrector determines that the pressure at the location of the second pressure sensor (S2) is equal to the atmospheric pressure when the amount of change in the detected pressure of the atmospheric pressure sensor and the amount of change in the detected pressure of the second pressure sensor are each maintained below a preset threshold change amount for a second reference time. Claim 16 A pressure sensor offset correction device of a fuel cell system according to claim 11, wherein the offset corrector stores information regarding a first sensor correction period (T1) for the first pressure sensor and a second sensor correction period (T2) for the second pressure sensor, and the offset corrector checks whether the first sensor correction period (T1) or the second sensor correction period (T2) has been reached, and if the first sensor correction period (T1) has been reached, corrects the offset of the first pressure sensor by the sum of the calculated first offset and the second offset, and if the second sensor correction period (T2) has been reached, corrects the offset of the second pressure sensor by the calculated second offset. Claim 17 A pressure sensor offset correction device for a fuel cell system according to claim 10, characterized in that the first pressure sensor is a gauge pressure sensor and the second pressure sensor is an absolute pressure sensor. Claim 18 A pressure sensor offset correction device for a fuel cell system according to claim 17, wherein the first pressure sensor is a nozzle pressure sensor located between the fuel supply valve and the ejector, and the second pressure sensor is an anode pressure sensor located between the rear end of the ejector and the anode inlet.

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