System and method for air charging of fuel cells

Abstract

Method for air charging a fuel cell, comprising: Calculating (S130), by a control element, a speed of an accelerator pedal; Setting (S230), by a controller, a first power request value of a fuel cell stack or a second power request value of the fuel cell stack, which is lower than the first power request value, according to the calculated speed; Controlling (S310), by the control member, an amount of air flow to be supplied to the fuel cell stack based on the first power request value or the second power request value; Determining (S170), by the control element, whether a vehicle is in an accelerated state when the calculated speed is greater than a reference speed by comparing the calculated speed with a previously set reference speed; and Resetting (S190) an acceleration detection, by the controller, to release the acceleration intention state when a depression amount of an accelerator pedal is smaller than a previously set reference depression amount, by comparing the detected depression amount of an accelerator pedal to the previously set reference depression amount.

Description

BACKGROUND(a) Technical area

[0001] The present invention relates to a technique for air supercharging a fuel cell, and more particularly, to a technique for air supercharging a fuel cell in which an amount of airflow to be supercharged is controlled taking into account an acceleration intention of a driver. (b) Description of the prior art

[0002] Generally, an engine is powered by fuel cell power in a fuel cell vehicle, and the power from the fuel cells is generated through a reaction between hydrogen and oxygen. Here, the oxygen is often supplied from atmospheric air using an air blower. At this time, the output of a fuel cell stack is determined by the supplied hydrogen and the required oxygen; that is, atmospheric air must be supplied beforehand to produce a set power output.

[0003] If air is not supplied in sufficient quantities, hydrogen cannot react sufficiently with oxygen, and thus the necessary power cannot be delivered. In this case, acceleration performance is limited, thereby reducing product commercialization. When an air blower is rapidly driven while a driver presses the accelerator pedal to satisfy acceleration performance, power is immediately delivered from a fuel cell. However, when this happens, energy is lost due to air loading, and the interior of a fuel cell stack dries out, thereby reducing the efficiency of the fuel cell stack.

[0004] The document US 2014 / 0 081 497 A1 discloses a system and a method for controlling a fuel cell system.

[0005] The document DE 10 2012 108 337 A1 discloses an automatic clutch control device comprising: a clutch arranged between a main drive unit and an input shaft of a transmission, a target clutch torque calculation section, a gear stage change control section, an accelerator pedal depression speed detection section, a judging section for judging whether an accelerator pedal depression speed exceeds at least a predetermined depression speed limit value.

[0006] Document DE 10 2013 106 604 A1 discloses a vehicle driving force suppression device. Driving force suppression is performed based on the presence of an obstacle located on an opposite side to the selected shift position.

[0007] The document US 2009 / 0 105 895 A1 discloses a fuel cell vehicle in which the amount of battery support for a fuel cell stack is appropriately adjusted according to the setting of a mode position and an accelerator opening change rate.

[0008] The description provided above as prior art of the present invention is merely for understanding the background of the present invention and should not be construed as being included in the prior art known to those skilled in the art. SUMMARY

[0009] An object of the present invention provides a technique for air charging a fuel cell in which the amount of excess airflow supplied is controlled by determining a driver's acceleration intention, and the required power for a fuel cell stack is adjusted according to the determined acceleration intention, thereby reducing energy loss and reduced performance of the fuel cell stack due to air charging.

[0010] A method for air-charging a fuel cell according to the present invention may include: calculating a speed of an accelerator pedal; setting a first output request value of a fuel cell stack or a second power request value of the fuel cell stack, which is less than the first power request value, corresponding to the value of the calculated speed; and controlling an amount of airflow to be supplied to the fuel cell stack according to the first set first power request value or the second power request value.

[0011] The method for air charging a fuel cell may further include an acceleration detection step that determines an accelerated state when the calculated speed is greater than a reference speed by comparing the calculated speed in the calculation step with a set reference speed.

[0012] The method for air charging a fuel cell may further include a resetting step of releasing the acceleration intention state when the detected depression amount of an accelerator pedal (ie, the amount by which an accelerator pedal is depressed) is smaller than the set reference depression amount by comparing the detected depression amount of an accelerator pedal with the previously set reference depression amount.

[0013] In the case of the current acceleration intention state, the first power request value of the fuel cell stack may be set in the setting step. The first power request value may correspond to a power value requested by a driver. If not in the current acceleration intention state, the second power request value of the fuel cell stack may be set to the setting step. The second power request value may be the value corresponding to a total available power value calculated by adding an available power value of a fuel cell stack corresponding to the amount of airflow currently supplied to a currently available power value of a battery.

[0014] If the vehicle is not currently in an acceleration intention state, the second power request value may be set in the setting step in the case where the power value requested by a driver is greater than the total available power value during a comparison step.

[0015] If the vehicle is not currently in an acceleration intention state, the first power request value may be set in the setting step in the case where the power value requested by a driver is not greater than the total available power value during a comparison step. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The above and other features of the present invention will now be described in detail with reference to certain exemplary embodiments thereof illustrated by the accompanying drawings, which are given hereinafter for the purpose of illustration only and are accordingly limiting of the present invention, and in which: Fig. 1A and Fig. 1B is a flow diagram illustrating a method for air charging a fuel cell according to an embodiment of the present invention.

[0017] It should be understood that the appended drawings, which provide a somewhat simplified representation of various preferred features of the present invention as disclosed herein, are not necessarily to scale, including, for example, specific dimensions, orientations, locations, and shapes which will be determined in part by the particular intended application and environment of use.

[0018] In the figures, reference numerals refer to the same or equivalent parts of the present invention throughout the several figures of the drawing. DETAILED DESCRIPTION OF THE INVENTION

[0019] Reference will now be made in detail to various embodiments of the present invention, examples of which are illustrated in the accompanying drawings and described below. While the invention will be described in conjunction with the exemplary embodiments, it is to be understood that this description is not intended to limit the invention to these exemplary embodiments. On the contrary, the invention is intended to cover the exemplary embodiments as well as various alternatives, modifications, equivalents, and other embodiments included within the spirit and scope of the invention as defined by the appended claims.

[0020] It is understood that the term “vehicle” or “vehicle-like” or any similar term as used herein is inclusive of motor vehicles in general, such as passenger automobiles, including sport utility vehicles (SUVs), buses, trucks, various commercial vehicles, watercraft, a variety of boats and ships, aircraft and the like, and including hybrid vehicles, electric vehicles, internal combustion engines, plug-in hybrid vehicles, hydrogen powered vehicles, and other alternative fuel vehicles (e.g., fuels derived from resources other than oil).

[0021] Additionally, it is assumed that the following methods are executed by at least one controller. The term controller refers to a hardware device that includes a memory and a processor for executing one or more steps, which should be interpreted as its algorithm structure. The memory is configured to store algorithm steps, and the processor is specifically configured to execute these so-called algorithm steps to perform one or more processes, which are described further below.

[0022] Furthermore, the control logic of the present invention may be embedded as non-transitory computer-readable media on a computer-readable medium containing executable program instructions executed by a processor, controller, or the like. Examples of computer-readable 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 may also be distributed among computer systems coupled to a network such that the computer-readable media is stored and executed in a distributed manner, e.g., through a telematics server or a controller area network (CAN).

[0023] Exemplary embodiments of a method for air charging a fuel cell according to an embodiment of the present invention will be described hereinafter in detail with reference to the accompanying drawings.

[0024] Fig. 1A and Fig.1B are each a flowchart showing a method for air-charging a fuel cell according to an exemplary embodiment of the present invention, wherein the method for air-charging a fuel cell may include the steps of: calculating the speed at which an accelerator pedal is depressed S130; setting a first power demand value or a second power demand value of a fuel cell stack, which is lower than the first power demand value, corresponding to the value of the calculated speed S230, S280-1 and S280-2; and controlling the amount of airflow to be supplied to the fuel cell stack according to the first set power demand value or the second power demand value S310, S320.

[0025] In the more detailed description of the method for air-charging a fuel cell according to an exemplary embodiment of the present invention, the calculation step S130 is performed when an accelerator pedal is operated S100. Specifically, the speed of an accelerator pedal refers to a depression speed of an accelerator pedal as a difference value of a depression amount of the accelerator pedal. That is, the power requested by the accelerator pedal is calculated by detecting the depression amount of an accelerator pedal S110 and differentiating the detected depression amount S130 before the calculation step S130 is performed. In the present exemplary embodiment, the speed of an accelerator pedal is calculated in the calculation step. However, the acceleration thereof can be calculated by any known method.

[0026] After the calculation step S130 is performed, an acceleration detection step S170 may be performed to determine whether a driver currently intends to accelerate the vehicle when the calculated speed is greater than a reference speed by comparing the calculated speed from the calculation step S130 with a set reference speed S150.

[0027] The reference speed refers to a speed value used to determine whether a driver has the intention to accelerate, and can be set differently depending on the designer's intention. Furthermore, determining that a driver has the intention to accelerate means that the pedal is currently depressed, causing the vehicle to accelerate.

[0028] By comparing the speeds of pedal depression by a driver S150, a controller performing the calculation steps can determine whether the driver is currently depressing an accelerator pedal to accelerate or maintain a normal driving speed, and thus the amount of air charging can be increased immediately only when the driver intends to accelerate, thereby preventing drying out of a fuel stack and damage to the inside thereof.

[0029] Meanwhile, after the acceleration detection step S170, a reset step S190 may be further performed to release the acceleration intention state when the detected depression amount of an accelerator pedal is less than a set reference depression amount by comparing the detected depression amount of an accelerator pedal with the set reference depression amount S180. Releasing the acceleration intention state means that the set acceleration intention state is released or terminated.

[0030] Accordingly, by considering the depression amount of the accelerator pedal, the acceleration intention in addition to the speed of the accelerator pedal, the acceleration intention of a driver can be determined by distinguishing between when a driver depresses the accelerator pedal and the acceleration intention when the accelerator pedal is depressed quickly due to vehicle vibration or other external causes.

[0031] Meanwhile, the first power request value of a fuel cell stack is set in the setting step S230 in the case of a current acceleration intention state, and here the first power request value may be a power value requested by a driver.

[0032] Setting the first power request value or the second power request value means determining the power value required for the fuel cell stack, wherein the power of the fuel cell stack corresponding to the set request value within the first power request value and the second power request value, that is, the electric current value generated by the fuel cell stack, is calculated S300, and the amount of air flow required is calculated S310, and then the flow amount of air is controlled by driving an air blower S320 in the control steps S310, S320.

[0033] Accordingly, when the current acceleration intention state is set to the first power request value S230 in step S200, the power value requested by a driver is calculated S210 based on the acceleration and the depression amount of an accelerator pedal, and the control steps S310, S320 are performed by setting the calculated power value requested by a driver (ie, the first power request value). At this time, the power value requested by a driver may be a torque value requested by a driver.

[0034] The power value requested by a driver does not necessarily need to be calculated after the acceleration intention state is set, but can be calculated simultaneously with the speed of an accelerator pedal, either after detecting the amount of acceleration pedal depression or before detecting the amount of acceleration pedal depression. The time for calculating the power value requested by a driver can be set variously. The torque value requested by a driver can also be calculated based on map data previously set from experiments, but is not limited to this.

[0035] Meanwhile, when not currently in the acceleration intent state, the second power demand value of a fuel cell stack is set in setting step S280-2. The second power demand value may be a torque value corresponding to a total available power value calculated by adding an available power value of a fuel cell stack corresponding to the amount of airflow currently being supplied to a currently available power value of a battery.

[0036] The available power value of a fuel cell stack is the available power value in an air supply state before the control step is performed by the first power demand value and the second power demand value, and may be a power value generated by a fuel cell stack in a current state, that is, an electric current power value. Furthermore, the currently available power value may be an amount of electric current currently remaining in a battery.

[0037] Accordingly, when not in the current acceleration intention state, the total available power value is calculated S220, the torque value corresponding to the total available power value is calculated S240, and it is compared whether the power value requested by a driver is greater than the torque value corresponding to the calculated total available power value S260. Here, if the power value requested by a driver is greater than the torque value corresponding to the calculated total available power value, the second power request value is set as the power value requested by the fuel cell stack S280-2.

[0038] The total available power value is not necessarily calculated after determining the current acceleration intent state, but can be calculated at any time. The corresponding torque value can be calculated using the preset data map, but is not limited to this.

[0039] In addition, when the vehicle is not currently in the acceleration distance, a comparison may be made as to whether the power value requested by a driver is greater than the torque value corresponding to the total available power value S260, and when the power value requested by a driver is not greater than the torque value corresponding to the total available power value, the first power request value may be set as the power value requested from the fuel cell stack S280-1.

[0040] Meanwhile, the control steps S310, S320 may be performed such that the power value requested by a driver is calculated as the electric current value requested by a fuel cell stack, and the total available power value calculated as an electric current value itself is used as the electric current value requested by the fuel cell stack, without separately calculating the torque requested by a driver or the torque value corresponding to the total available power value S240, and then calculating the current value requested by the fuel cell stack corresponding to the torque value S300. In addition, the first power request value, the second output request value, and the power value requested by a driver are referred to as electric current values.

[0041] According to a method for air-charging a fuel cell configured as above, the electric current required for a fuel cell is doubled by determining the acceleration intention of a driver, and thus, the air-charging that occurs when the electric current required for the fuel cell is calculated by the torque requested by a driver, and the performance degradation of the fuel cell stack caused by the drying out of the inside thereof can be prevented, and at the same time, the performance degradation of acceleration can be eliminated, thereby improving fuel efficiency and acceleration performance.

[0042] In more detail, the amount of airflow is increased immediately to generate the torque requested by a driver to improve acceleration when the driver accelerates. However, when the torque requested by a driver is greater than the torque value corresponding to the total available power value while a driver is traveling at a constant speed, power must be output within a range by adding an available power output from a battery to the output of the fuel cell stack corresponding to the amount of airflow currently supplied, rather than increasing the amount of airflow, thereby preventing energy loss and performance degradation of the fuel cell stack that can occur due to excessively increasing the amount of airflow to improve fuel efficiency.

Claims

[1] Method for air charging a fuel cell, comprising: Calculating (S130), by a control element, a speed of an accelerator pedal; Setting (S230), by a controller, a first power request value of a fuel cell stack or a second power request value of the fuel cell stack, which is lower than the first power request value, according to the calculated speed; Controlling (S310), by the control member, an amount of air flow to be supplied to the fuel cell stack based on the first power request value or the second power request value; Determining (S170), by the control element, whether a vehicle is in an accelerated state when the calculated speed is greater than a reference speed by comparing the calculated speed with a previously set reference speed; and Resetting (S190) an acceleration detection, by the controller, to release the acceleration intention state when a depression amount of an accelerator pedal is smaller than a previously set reference depression amount, by comparing the detected depression amount of an accelerator pedal to the previously set reference depression amount. [2] The method according to claim 1, wherein when the vehicle is in the acceleration intention state, the first power request value of the fuel cell stack is set in the setting step. [3] The method of claim 1, wherein the first power request value corresponds to a power value requested by a driver. [4] The method of claim 1, wherein when the vehicle is not in the acceleration intention state, the second power request value of the fuel cell stack is set. [5] The method of claim 1, wherein the second power request value is the value corresponding to a total available power value calculated by adding an available power value of a fuel cell stack corresponding to the amount of airflow currently delivered to a currently available power value of a battery. [6] The method of claim 5, wherein when the vehicle is not in the acceleration intent state, the second power request value is set when the power value requested by a driver is greater than the total available power value. [7] The method of claim 5, wherein when the vehicle is not in the acceleration intention state, the first power request value is set when the power value requested by a driver is not greater than the total available power value. [8] A non-transitory computer-readable medium containing program instructions executed by a processor or controller, the non-transitory computer-readable medium comprising: Program instructions that calculate a speed of an accelerator pedal; Program instructions that set a first power request value of a fuel cell stack or a second power request value of the fuel cell stack that is less than the first power request value, corresponding to the calculated speed; Program instructions that control an amount of airflow to be delivered to the fuel cell stack based on the set first power request value or the second power request value; Program instructions that determine whether a vehicle is in an accelerated state when the calculated speed is greater than a reference speed by comparing the calculated speed with a preset reference speed; and Program instructions that reset an acceleration detection to release the acceleration intention state when a depression amount of an accelerator pedal is less than a previously set reference depression amount by comparing the detected depression amount of an accelerator pedal with the previously set reference depression amount. [9] The non-transitory computer-readable medium according to claim 8, wherein, when the vehicle is in the acceleration intention state, the first power request value of the fuel cell stack is set in the setting step. [10] The non-transitory computer readable medium of claim 8, wherein the first power request value corresponds to a power value requested by a driver. [11] The non-transitory computer-readable medium according to claim 8, wherein when the vehicle is not in the acceleration intention state, the second power request value of the fuel cell stack is set. [12] The non-transitory computer-readable medium of claim 8, wherein the second power request value is the value corresponding to a total available power value calculated by adding an available power value of a fuel cell stack corresponding to the amount of airflow currently delivered to a currently available power value of a battery. [13] The non-transitory computer readable medium of claim 12, wherein when the vehicle is not in the acceleration intention state, the second power request value is set when the power value requested by a driver is greater than the total available power value. [14] The non-transitory computer readable medium of claim 12, wherein when the vehicle is not in the acceleration intention state, the first power request value is set when the power value requested by a driver is not greater than the total available power value.

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