Method, device and system for improving fuel efficiency of fuel cell electric vehicle

Abstract

The present application discloses a method for improving the fuel efficiency of a fuel cell electric vehicle and a fuel cell electric vehicle fuel efficiency improving device and system. The method includes: collecting navigation information and vehicle speed information; calculating a glide line when a specific event point is sensed based on the navigation information; judging whether deceleration is required by comparing the current driving speed with the glide line speed corresponding to the current position; and when deceleration is required as a result of the judgment, changing the standard for judging whether to enter a fuel cell stop (FC STOP) state.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2019-0167082 filed on December 13, 2019, in the Korean Intellectual Property Office, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to a fuel cell electric vehicle, and more particularly, to a technology for improving the fuel efficiency of a fuel cell electric vehicle by utilizing navigation information in a fuel cell-power storage unit hybrid vehicle having a fuel cell as a main power source and a power storage unit (battery) as an auxiliary power source. Background Art

[0004] In recent years, with the depletion of fossil fuels and environmental pollution due to exhaust gas, alternative energy sources have been actively developed to solve environmental problems such as global warming. In particular, in the automotive field, research is actively being conducted on the use of fuel cell systems as a power source for vehicles, and compared with conventional power generation methods, fuel cell systems are evaluated as future power generation technologies because they have high power generation efficiency and power generation does not cause pollutant emissions.

[0005] A fuel cell is a power generation device that converts the chemical energy of a fuel into electrical energy by an electrochemical reaction in a fuel cell stack, rather than converting chemical energy into heat by combustion. Fuel cells can provide electricity not only for industrial, household and vehicle driving, but also for small electrical / electronic products, especially portable devices.

[0006] When a fuel cell is used only as a power source of a vehicle, the fuel cell bears all loads constituting the vehicle, so that performance degradation may occur in a driving area where the efficiency of the fuel cell is low.

[0007] In addition, in a high-speed running area where a high voltage is required, due to the output characteristics in which the output voltage drops sharply, a sufficient voltage required to drive the motor cannot be provided, thereby reducing the acceleration performance of the vehicle.

[0008] In addition, when a load is suddenly applied to the vehicle, the fuel cell output voltage suddenly drops and insufficient power is supplied to the drive motor, thereby reducing vehicle performance (because electricity is generated by chemical reactions, sudden load changes are unreasonable for fuel cells).

[0009] In addition, because the fuel cell has a unidirectional output characteristic, the energy output from the drive motor cannot be recovered when the vehicle brakes, which may reduce the efficiency of the vehicle system.

[0010] A fuel cell-power storage unit hybrid vehicle is a hydrogen electric vehicle that is driven by rotating a driving motor using electric energy supplied from a fuel cell as a main power source and a power storage unit (super capacitor or battery) as an auxiliary power source to generate driving force.

[0011] A hybrid vehicle in which a fuel cell and a power storage unit are directly connected to each other is driven by continuously outputting constant power from the fuel cell. When there is surplus power, the power storage unit is charged with the excess power. When there is insufficient power, a driving mode is applied in which the insufficient power is supplemented by the power storage unit.

[0012] In order to increase the fuel efficiency of hydrogen electric vehicles, it is necessary to minimize unnecessary fuel cell driving.

[0013] In order to improve the fuel efficiency of hydrogen electric vehicles, the process of stopping and resuming fuel cell power generation when necessary during the operation of hydrogen electric vehicles [fuel cell stop (FC STOP) / fuel cell restart (FC RESTART) process] should be given priority consideration, that is, the idle stop (idle stop) / release control process [fuel cell on (on) / off (off) control process] of temporarily stopping fuel cell power generation in fuel cell-battery, fuel cell-supercapacitor hybrid vehicles. The idle stop of the fuel cell during vehicle operation is significantly different from the complete shutdown (shut down) of the fuel cell system after the vehicle is completely stopped. Therefore, it is necessary to clearly distinguish the idle stop control process of the fuel cell and the system shutdown control process.

[0014] Since a conventional hydrogen electric vehicle does not require driving force in a stopped state or a decelerated state, a fuel cell control logic is used that temporarily stops driving of the fuel cell to prevent unnecessary energy consumption.

[0015] Additionally, conventional hydrogen electric vehicles have utilized fuel cell control logic that enters a fuel cell stop state after motor torque drops below a certain level and enters a regenerative braking step.

[0016] However, there is a need to provide a method capable of maximizing the fuel efficiency improvement effect of a hydrogen electric vehicle, which is different from the prior art. Summary of the invention

[0017] The present disclosure is proposed to solve the above-mentioned problems occurring in the prior art while keeping the advantages achieved by the prior art intact.

[0018] Aspects of the present disclosure provide a fuel efficiency improving method of a fuel cell electric vehicle using navigation information, and a fuel efficiency improving apparatus and system of a fuel cell electric vehicle.

[0019] Another aspect of the present disclosure provides a method for improving the fuel efficiency of a fuel cell electric vehicle using navigation information, as well as a device and system for improving the fuel efficiency of a fuel cell electric vehicle, which can quickly and accurately enter a fuel cell stop state by predicting vehicle deceleration in advance based on map information obtained from navigation, thereby improving fuel efficiency.

[0020] Another aspect of the present disclosure provides a method for improving the fuel efficiency of a fuel cell electric vehicle using navigation information, as well as a device and system for improving the fuel cell electric vehicle, which can increase the durability of the fuel cell stack by actively entering a fuel cell stop state to minimize the operating time of the fuel cell stack relative to the vehicle mileage.

[0021] The technical problems to be solved by the present inventive concept are not limited to the above-mentioned problems, and any other technical problems not mentioned herein will be clearly understood by those skilled in the art to which the present disclosure pertains from the following description.

[0022] According to one aspect of the present disclosure, a method for improving the fuel efficiency of a fuel cell electric vehicle includes: collecting navigation information and vehicle speed information; calculating a glide path when a specific event point is sensed based on the navigation information; determining whether deceleration is required by comparing a current driving speed with a glide path speed corresponding to a current position; and when deceleration is required as a result of the determination, changing a standard for determining whether to enter a fuel cell stop (FC STOP) state.

[0023] According to an embodiment, the glide line may be calculated based on a glide descent constant value which is a unique value of the vehicle and the weight of the vehicle.

[0024] According to an embodiment, the navigation information may include: slope information which is a road inclination from the current position to the event point; and distance information from the current position to the event point.

[0025] According to an embodiment, the method may further include correcting the calculated glide line by using the slope information and the distance information.

[0026] According to an embodiment, determining whether deceleration is required may include: determining that deceleration is required when the current driving speed is equal to or greater than the taxiline speed; and determining that deceleration is not required when the current driving speed is less than the taxiline speed.

[0027] According to an embodiment, the change criteria may include adjusting a motor torque reference value for entering the FC STOP state to a specific level when the current driving speed is equal to or greater than the taxiing line speed, and entering the FC STOP state when the current motor torque is less than the motor torque reference value.

[0028] According to an embodiment, navigation information may be received from a navigation device through a controller area network (CAN) communication, and vehicle speed information may be received from a driving controller through CAN communication.

[0029] According to an embodiment, the driving controller may include at least one of a brake controller, an accelerator controller, and a wheel sensor.

[0030] According to an embodiment, navigation information and vehicle speed information may be received from a navigation device through CAN communication.

[0031] According to an embodiment, the event point may include at least one of a road branch starting point, a highway toll station entrance / exit point, a speed bump, a speed camera location, a speed limit change point, a safe driving interval starting point, a congested interval starting point, a sharp turn interval starting point, and a right turn point.

[0032] According to one aspect of the present disclosure, a fuel cell system controller for controlling a fuel cell system includes: a communication device that collects navigation information and vehicle speed information; a calculation device that calculates a glide line when a specific event point is sensed based on the navigation information; a judgment device that judges whether deceleration is required by comparing a current driving speed with a glide line speed corresponding to a current position; and a change device that changes a standard for judging whether to enter a fuel cell stop (FC STOP) state when deceleration is required as a result of the judgment.

[0033] According to an embodiment, the calculation device may calculate the glide line based on a glide descent constant value which is a unique value of the vehicle and the weight of the vehicle.

[0034] According to an embodiment, the navigation information may include: slope information which is a road inclination from the current position to the event point; and distance information from the current position to the event point.

[0035] According to an embodiment, the fuel cell system controller may further include: a correction device that corrects the calculated glide line by using the slope information and the distance information.

[0036] According to an embodiment, the judging device may judge that deceleration is required when the current driving speed is equal to or greater than the taxiing line speed, and judge that deceleration is not required when the current driving speed is less than the taxiing line speed.

[0037] According to an embodiment, the changing device can adjust the motor torque reference value for entering the FC STOP state to a specific level when the current driving speed is equal to or greater than the coasting line speed, and enter the FC STOP state to stop the air compressor of the fuel cell system when the current motor torque is less than the motor torque reference value.

[0038] According to an embodiment, navigation information may be received from a navigation device through a controller area network (CAN) communication, and vehicle speed information may be received from a driving controller through CAN communication.

[0039] According to an embodiment, the driving controller may include at least one of a brake controller, an accelerator controller, and a wheel sensor.

[0040] According to an embodiment, navigation information and vehicle speed information may be received from a navigation device through CAN communication.

[0041] According to an embodiment, the event point may include at least one of a road branch starting point, a highway toll station entrance / exit point, a speed bump, a speed camera location, a speed limit change point, a safe driving interval starting point, a congested interval starting point, a sharp turn interval starting point, and a right turn point.

[0042] The objects of the present inventive concept may not be limited to the above contents, and other objects will be clearly understood by those of ordinary skill in the art from the following disclosure. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] The above and other objects, features and advantages of the present disclosure will become more apparent through the following detailed description in conjunction with the accompanying drawings:

[0044] Figure 1 is a view showing the structure of a fuel cell system according to an embodiment of the present disclosure;

[0045] Figure 2 is a block diagram showing a power system of a fuel cell-supercapacitor hybrid vehicle according to an embodiment of the present disclosure;

[0046] Figure 3 is a view showing a process of entering a fuel cell stop mode in a hydrogen electric vehicle according to an embodiment of the present disclosure;

[0047] Figure 4 is a view showing a fuel efficiency improvement system of a fuel cell electric vehicle according to an embodiment of the present disclosure;

[0048] Figure 5 is a view showing a method of calculating a coast line in a fuel cell system controller according to an embodiment;

[0049] Figure 6 is a view showing a method of correcting a glide line by reflecting gradient information in a fuel cell system controller according to an embodiment;

[0050] Figure 7 is a diagram showing a method of determining whether deceleration is required by using vehicle speed information in a fuel cell system controller according to an embodiment;

[0051] Figure 8 is a view showing a method of changing an FC STOP state entering condition in a fuel cell system controller according to an embodiment; and

[0052] Fig. 9 is a view showing the fuel efficiency improvement effect of a fuel cell electric vehicle according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0053] Hereinafter, some embodiments of the present disclosure will be described in detail with reference to the exemplary drawings. When adding reference numerals to the components of each drawing, it should be noted that the same or equivalent components are represented by the same reference numerals even if they are shown in other drawings. In addition, when describing the embodiments of the present disclosure, detailed descriptions of well-known features or functions will be omitted so as not to unnecessarily obscure the subject matter of the present disclosure.

[0054] When describing components according to embodiments of the present disclosure, terms such as "first", "second", "A", "B", "(a)", "(b)", etc. may be used. These terms are intended only to distinguish one component from another, and these terms do not limit the nature, order, or sequence of the constituent components. Unless otherwise defined, all terms used herein, including technical terms or scientific terms, have the same meanings as those generally understood by a person of ordinary skill in the art to which the present disclosure belongs. Terms such as those defined in general dictionaries should be interpreted as having the same meanings as the contextual meanings in the relevant technical field, and should not be interpreted as having idealized or overly formalized meanings unless expressly defined as having such meanings in this application.

[0055] In the following, reference will be made to Figures 1 to 9 The embodiments are described in detail.

[0056] Briefly describing the configuration of the fuel cell system to help understand the present disclosure, the most studied polymer electrolyte membrane fuel cell (PEMFC) as a power source for driving vehicles includes: a membrane electrode assembly (MEA) in which catalyst electrode layers for electrochemical reactions are attached to both sides of an electrolyte membrane for moving hydrogen ions; a gas diffusion layer (GDL) for uniformly distributing the reaction gas and transmitting the generated electrical energy; gaskets and fasteners for maintaining airtightness and tightening pressure between the reaction gas and cooling water; and a separator plate (bipolar plate) for moving the reaction gas and cooling water.

[0057] In a fuel cell, hydrogen as a fuel and oxygen (air) as an oxidant are supplied to the anode and cathode of the membrane electrode assembly respectively through the flow path of the separator plate. Hydrogen is supplied to the anode (also called "fuel electrode" or "hydrogen electrode" or "oxidation electrode"), and oxygen (air) is supplied to the cathode (also called "air electrode", "oxygen electrode" or "reduction electrode"). The hydrogen supplied to the anode is decomposed into hydrogen ions (protons, H+) and electrons (e-) by the catalyst of the electrode layer formed on both sides of the electrolyte membrane, wherein only hydrogen ions are selectively transmitted to the cathode through the electrolyte membrane as a proton exchange membrane, and at the same time, electrons are transmitted to the cathode through the gas diffusion layer and the separator plate as a conductor. In the cathode, the hydrogen ions supplied through the electrolyte membrane and the electrons transmitted through the separator plate meet and react with the oxygen in the air supplied to the cathode through the air supply device to produce water. In this case, due to the movement of hydrogen ions, electron flow occurs through the external wire, thereby generating current due to the flow of electrons.

[0058] Figure 1 is a view showing the structure of a fuel cell system according to an embodiment of the present disclosure.

[0059] The fuel cell system according to the embodiment may include an air supply device and a hydrogen supply device.

[0060] like Figure 1 As shown, the dry air supplied by the blower 28 is humidified by the humidifier 29 and then supplied to the cathode of the fuel cell stack 2. The exhaust gas of the cathode is transmitted to the humidifier 29 in a state humidified by the water component generated in the cathode, and is used to humidify the dry air supplied to the cathode by the blower 28.

[0061] The hydrogen supply device includes two pipelines, wherein the first pipeline supplies hydrogen to the anode of the fuel cell stack 2 through a low pressure regulator (LPR) 23 , and a portion of the hydrogen at the anode outlet is recirculated through a hydrogen recirculation blower 24 .

[0062] The second line supplies high-pressure hydrogen directly to the anode through a valve 25 and an injector 26 , and a portion of the hydrogen at the anode outlet is recycled and supplied through the injector 26 .

[0063] Hydrogen crossover refers to a phenomenon in which residual hydrogen remaining in the anode directly passes through the electrolyte membrane and reacts with oxygen in the cathode without generating electricity.

[0064] In order to reduce the amount of hydrogen permeation, the anode pressure should be reduced in the low output interval that reduces the output of the cell stack, and the anode pressure should be increased in the high output interval that increases the output of the cell stack. This can be solved by using the low pressure regulator 23 alone when low pressure is required and supplying high pressure hydrogen through the control of valve 25 when high pressure or purge of hydrogen is required.

[0065] As the anode pressure (hydrogen pressure) increases, the amount of hydrogen permeation increases. Since hydrogen permeation adversely affects fuel efficiency and fuel cell durability, it is necessary to maintain an appropriate anode pressure.

[0066] The hydrogen purge valve 27 is used to ensure the performance of the battery stack by discharging impurities and condensed water at the anode end. The anode outlet is connected to a water trap 31, and when condensed water is stored and the amount of condensed water reaches a certain level, the condensed water is discharged through a valve 32.

[0067] Meanwhile, driving modes of hybrid vehicles including a fuel cell as a main power source and a supercapacitor as an auxiliary power source (or a high-voltage battery as a secondary battery) can be classified into: a fuel cell driving mode (EV mode), in which a motor is driven only by using a fuel cell as a power source; a hybrid (HEV) mode, in which a motor is driven by using a fuel cell and a supercapacitor as power sources; and a regenerative braking mode, in which the supercapacitor is charged.

[0068] Figure 2 is a block diagram illustrating a power system of a fuel cell-supercapacitor hybrid vehicle according to an embodiment of the present disclosure.

[0069] Reference Figure 2 , a fuel cell-supercapacitor hybrid vehicle may include: a fuel cell system 110 including a fuel cell (stack) as a main power source and fuel cell accessories (blower, hydrogen recirculation blower, water pump, etc.); a fuel cell system controller 111 for system drive control of fuel cell accessories, etc.; a power conversion device 120; a supercapacitor 131 as an auxiliary power source; and an inverter 141 for driving a motor 142. In this case, a voltage sensor 132 and a current sensor 133 may be connected to the supercapacitor 131.

[0070] The power conversion device 120 may include: a step-up / down converter 121, installed between the fuel cell system 110 and the supercapacitor 131 to serve as a load for constant current operation of the fuel cell, so that a constant current is output from the fuel cell system 110; a direct connection switch 125, installed between the fuel cell system 110 and the supercapacitor 131 to selectively directly connect / block the fuel cell system 110 and the supercapacitor 131; a converter controller 122, which is used to control the drive of the step-up / down converter 121 by sensing the output terminal voltage of the step-up / down converter 121 through a voltage sensor 124; and a power distribution controller 123, which controls the converter controller 122 and the drive of the direct connection switch 125 as an upper controller for selecting and controlling the operation mode of the fuel cell system 110.

[0071] Operation mode selection and control of the fuel cell system 110 may be performed by cooperative control among controllers including the power distribution controller 123 , the fuel cell system controller 111 , the converter controller 122 , and the like.

[0072] As indicated, the fuel cell system 110 can drive and control system components such as fuel cell accessories so that a current corresponding to the amount of load applied to the output side of the fuel cell stack can be output from the fuel cell stack. That is, when the load applied to the output side draws current, system control that performs stack current output corresponding to the load in the fuel cell system 110 can be performed.

[0073] Therefore, when the load amount on the output side of the battery stack is specifically set by the boost / buck operation of the boost / buck converter 121, the components of the fuel cell system 110 are controlled to achieve the corresponding stack current output. Therefore, when the load amount is appropriately adjusted by controlling the drive of the boost / buck converter 121, the constant output operation of the battery stack can be performed at the desired operating point. When the boost / buck converter 121 performs the boost / buck operation as needed to fix the load amount on the output side of the battery stack, the output current value of the fuel cell is fixed, so that the constant output operation can be achieved.

[0074] The direct connection switch 125 according to the embodiment may be a relay or an insulated gate bipolar transistor (IGBT) element. Since the fuel cell system 110 and the super capacitor 131 can be selectively directly connected or blocked by the direct connection switch 125, the degree of freedom of fuel cell output control can be increased compared to a conventional fuel cell-super capacitor direct connection system, and therefore, this embodiment may be advantageous in terms of fuel efficiency and fuel cell protection.

[0075] Figure 3is a view showing a process of entering a fuel cell stop mode in a hydrogen electric vehicle according to an embodiment of the present disclosure.

[0076] In order to increase the fuel efficiency of hydrogen electric vehicles, it is necessary to minimize unnecessary fuel cell operations.

[0077] Since driving force is not required in a stopped state or a decelerated state, it is effective to improve fuel efficiency by temporarily stopping the driving of the fuel cell to prevent unnecessary fuel consumption, which is called a fuel cell stop (FC STOP).

[0078] Reference Figure 3 , reference numerals 310 and 320 are graphs showing a change in vehicle speed from a first speed (e.g., 90 km / h) to a second speed (e.g., 0 km / h) and a change in motor torque according to the change in vehicle speed, respectively. Reference numerals 330 and 340 are graphs showing a change in FC STOP state according to a change in motor torque and a change in air compressor RPM according to a change in FC STOP state, respectively.

[0079] Referring to reference numerals 310 and 320, when the vehicle speed decreases during driving, the motor torque also decreases accordingly, and when the motor torque drops below the preset FC STOP entry reference value 325 as shown in reference numerals 321 to 324, as shown in reference numerals 331 to 334, the FC STOP state signal changes from a low state to a high state, causing the fuel cell system to enter the FC STOP mode (or FC STOP state).

[0080] When entering the FC STOP mode, as shown in the figure numerals 341 to 344, the RPM of the air compressor is sharply reduced, that is, the air compressor is stopped, so that the fuel cell system can switch from the normal driving state to a temporary stop state, that is, an idle state. Therefore, when the fuel cell system enters the FC STOP mode, the energy consumed by the air compressor can be saved.

[0081] Figure 4 is a view showing a fuel cell electric vehicle fuel efficiency improvement system according to an embodiment of the present disclosure.

[0082] Hereinafter, for the convenience of description, the fuel cell electric vehicle fuel efficiency improvement system is simply referred to as the fuel efficiency improvement system 400 .

[0083] Reference Figure 4 The fuel efficiency improvement system 400 may basically include a navigation device 410 , a fuel cell system controller 420 , and a driving controller 430 .

[0084] The driving controller 430 according to an embodiment may include at least one controller and sensor for driving speed control, for example, at least one of a brake controller, an accelerator controller, and a wheel sensor.

[0085] The navigation device 410 , the fuel cell system controller 420 , and the steering controller 430 may be connected to a controller area network (CAN) bus to exchange information.

[0086] According to the embodiment, the navigation device 410 may include: a first communication device 411 for CAN communication; a distance calculation device 412 for calculating the distance from the current position to the deceleration target; a slope calculation device 413 for calculating the average road slope from the current position to the deceleration target; an event sensing device 414 for sensing a deceleration event; a path guidance device 415 for performing basic path guidance or destination path guidance to a destination set by a user; and a memory 416 for storing various traffic information and map information used for path guidance.

[0087] According to an embodiment, the event sensing device 414 can determine the starting point of a road branch, the entrance / exit point of a highway toll station, a speed bump, a speed camera location, a speed limit change point, the starting point of a safe driving interval, the starting point of a congested interval, the starting point of a sharp turn interval, a right turn point, etc. as a deceleration target.

[0088] The event sensing device 414 may refer to the memory 416 to sense a deceleration target on the driving path and identify a deceleration event corresponding to the sensed deceleration target.

[0089] The distance calculation device 412 and the slope calculation device 413 may respectively calculate the distance from the current position to the sensed deceleration target and the slope which is the average road inclination from the current position to the sensed deceleration target according to the identified deceleration event.

[0090] The navigation device 410 may transmit the deceleration event information, the calculated distance from the current position to the event point corresponding to the deceleration event, and the slope information which is the average road inclination information from the current position to the event point to the fuel cell system controller 420 through the first communication device 411 .

[0091] The driving controller 430 may include: a third communication device 431 for performing CAN communication; and a vehicle speed information generating device 432 for generating a current vehicle speed, ie, current driving speed information.

[0092] According to an embodiment, the driving controller 430 may transmit the current vehicle speed information to the fuel cell system controller 420 through CAN communication.

[0093] The fuel cell system controller 420 according to another embodiment of the present disclosure may acquire current vehicle speed information from the navigation device 410 .

[0094] The fuel cell system controller 420 may include a second communication device 421 , a calculation device 422 , a correction device 423 , a judgment device 424 , a change device 425 , and a controller 426 .

[0095] The fuel cell system controller 420 may obtain deceleration event information, slope information, distance information, and current vehicle speed information through the second communication device 421 .

[0096] The calculation device 422 can calculate the glide line from the current position to the deceleration target, i.e., the event point, based on the glide descent constant value as a unique value of the vehicle and the weight of the vehicle. That is, the calculation device 422 can calculate the glide line from the event point as the deceleration end position to the current vehicle position.

[0097] The coasting line refers to a speed profile for executing coasting descent so that the speed of the vehicle becomes a target speed (eg, 30 kph) at an event point where deceleration occurs (eg, right turn).

[0098] Whenever a deceleration event occurs, the computing device 422 can calculate the taxiline from the point where the deceleration event occurs to the current position. Figure 5 Description, the method of calculating the glide line will become more obvious.

[0099] The correction means 423 can correct the glide path calculated by the calculation means 422 by reflecting the slope information. That is, the correction means 423 can improve the accuracy of the glide path calculated by the calculation means 422 by reflecting the road inclination from the deceleration target to the current position. Figure 6 With the description above, the glide line correction method of the correction device 423 will become more apparent.

[0100] The judging device 424 can judge whether deceleration is required by comparing the current driving speed with the glide speed at the current position on the corrected glide line.

[0101] When the current driving speed is greater than or equal to the taxi line speed, the judging device 424 according to the embodiment may judge that deceleration is required. On the contrary, when the current driving speed is less than the taxi line speed, the judging device 424 may judge that deceleration is not required.

[0102] As an example, when the current driving speed is greater than the taxi line speed, the mode enters the FC STOP mode because the driver can reduce the speed by stepping on the brake. On the contrary, when the current driving speed is less than the taxi line speed, the mode does not enter the FC STOP mode because the driver may continue to accelerate slightly.

[0103] Through the later described Figure 7 With reference to the description above, the method of determining whether to decelerate by comparing the speed of the determining device 424 will become more obvious.

[0104] The changing means 425 can dynamically change the FC STOP state entering condition based on the determination result of the determining means 424 .

[0105] As an example, when the judging device 424 judges that deceleration is required, the changing device 425 can change the motor torque reference value used to judge whether to enter the FC STOP mode to a specific level higher than the currently set motor torque reference value. On the contrary, when deceleration is not required, the motor torque reference value used to enter the FC STOP mode can be maintained.

[0106] When the motor torque reference value for entering the FC STOP mode is increased by the changing device 425, that is, when the FC STOP mode entry condition is relaxed, the fuel cell system enters the FC STOP mode faster than before. Therefore, the fuel efficiency of the fuel cell electric vehicle can be improved. Figure 8 The method of changing the FC STOP entry condition of the changing device 425 will become more obvious with the description of FIG.

[0107] The controller 426 may determine whether to enter the FC STOP mode by comparing the current motor torque with a set motor torque reference value.

[0108] For example, when the current motor torque drops below the motor torque reference value, the controller 426 may control the FCSTOP state signal to be high, thereby causing the fuel cell system to enter the FC STOP mode.

[0109] Figure 5 is a view showing a method of calculating a glide line in a fuel cell system controller according to an embodiment.

[0110] Reference Figure 5 In S510, the calculation device 422 of the fuel cell system controller 420 may calculate the glide line "F" based on the glide descent constants f0, f1, and f2 as unique values ​​of the vehicle and the vehicle weight "M".

[0111] In this case, "F" can be expressed as "A+B*V+C*V2 ”, as shown by the reference numerals 561 and 562.

[0112] In addition, the time “T” (ie, T2 − T1 ) taken when reaching the target speed V1 when passing the corresponding event point from the travel speed V2 at the current time point T1 may be represented as a formula of reference numeral 563 .

[0113] Referring to reference numeral 564, for a taxiline represented as a speed-time function, the integrated value from T1 to T2 represents the distance "S" traveled from speed V2 to speed V1.

[0114] Figure 6 is a view showing a method of correcting a glide line by reflecting slope information in a fuel cell system controller according to an embodiment.

[0115] Reference Figure 6 In S520 , the correction device 423 of the fuel cell system controller 420 may correct the glide line “F” calculated by the calculation device 422 based on the slope information received from the navigation device 410 .

[0116] Referring to reference numeral 570, in flat ground, the glide line "F" can be expressed as "A+B*V+C*V 2 ”.

[0117] When the road slope from the current vehicle position to the event point is “θ”, the glide line “F” reflecting the slope information can be expressed as “A+B*V+C*V 2 +Mg*sinθ". Where Mg is the slope constant. The slope constant can be unique to the vehicle.

[0118] According to the embodiment, the correction device 423 can use the slope information received from the navigation device 410 when deceleration is required and the distance information from the current vehicle position to the event point to calculate the average slope of the corresponding road section, and can correct the sliding line according to the increase and decrease of the force acting on the vehicle during uphill and downhill driving as shown in the figure mark 571.

[0119] Figure 7 1 is a diagram showing a method of determining whether FC STOP, ie, deceleration, is required by using vehicle speed information in a fuel cell system controller according to an embodiment.

[0120] Reference Figure 7 In S530, the judgment device 424 of the fuel cell system controller 420 can judge whether deceleration is required by comparing the current driving speed based on the vehicle speed information received from the driving controller 430 with the glide line speed at the current vehicle position on the glide line "F" corrected by the correction device 423.

[0121] In S560, when the current driving speed is less than the glide line speed, the judging device 424 may judge that it is not necessary to decelerate the vehicle and maintain the current situation state without entering the FC STOP state.

[0122] When the current driving speed is greater than or equal to the taxiing line speed, the judging device 424 may judge that the vehicle needs to be decelerated.

[0123] Referring to reference numeral 580, when a specific event such as a right turn, a speed camera, etc. is sensed during high-speed driving and the current driving speed Vu at the current vehicle position is greater than the glide line Vc, the judgment device 424 can judge that the vehicle needs to slow down and predict entering FC STOP.

[0124] On the other hand, even if the event is sensed during low-speed driving, when the current driving speed Vu at the current vehicle position is less than the coasting speed Vc, the judgment device 424 can also judge that there is no need to decelerate the vehicle and predict not to enter FCSTOP.

[0125] Figure 8 is a view showing a method of changing an FC STOP state entering condition in a fuel cell system controller according to an embodiment.

[0126] Reference Figure 8 In S550, when it is determined that the current driving speed is less than the coasting line speed and the vehicle does not need to be decelerated, the changing device 425 of the fuel cell system controller 420 may adjust upward the motor torque reference value for entering the FC STOP state.

[0127] When the motor torque is less than the motor torque at a specific motor speed, the vehicle may enter the FC STOP state.

[0128] Referring to reference numeral 590 , an FC STOP entry motor torque baseline may be defined, which provides a standard for identifying a motor torque at which each vehicle can enter an FC STOP state at a current driving speed. For ease of description, the FC STOP entry motor torque baseline is referred to as a baseline.

[0129] The changing device 425 according to the embodiment may dynamically change the FC STOP entry motor torque baseline based on the difference between the current travel speed and the glide line speed.

[0130] For example, when the current driving speed is greater than the taxiing line speed by a first value, the baseline may be adjusted upward to a first correction line.

[0131] As another example, when the current driving speed is greater than the taxiing line speed by a second value, the baseline may be adjusted upward to a second correction line, wherein the second value is greater than the first value.

[0132] Assume that the FC STOP entry motor torque baseline is changed to the second correction line based on event sensing. In this case, although the vehicle's current motor torque 591 is above the baseline before the change, the current motor torque 591 is below the second correction line, so that the vehicle can enter the FC STOP state.

[0133] Assume that the FC STOP entry motor torque baseline is changed to the first correction line based on event sensing. In this case, since the current motor torque 591 of the vehicle is located at the first correction line and above the baseline before the change, the vehicle does not enter the FC STOP state.

[0134] As will be described later Fig. 9 As shown, when the current driving speed is greater than the coasting line speed after event sensing during driving, the fuel cell system controller 420 according to the present disclosure enters the FC STOP state faster, thereby improving fuel efficiency by advancing the air compressor stop time point.

[0135] Fig. 9 is a view showing the fuel efficiency improvement effect of a fuel cell electric vehicle according to an embodiment of the present disclosure.

[0136] Reference Fig. 9 When the fuel cell system controller 420 senses an event point ahead, i.e., a point where deceleration is required, based on navigation information during driving, the fuel cell system controller 420 calculates and corrects the glide line. The fuel cell system controller 420 can determine whether deceleration is required by comparing the current driving speed with the speed corresponding to the current position on the corrected glide line, i.e., the glide line speed.

[0137] The fuel cell system controller 420 according to the embodiment may compare the current driving speed with the coasting speed at a point "A" before the first distance from the event point "B" to determine whether deceleration is required. For example, the first distance may be 800m, but is not limited thereto, and may be longer or shorter according to the design of a person skilled in the art. As another example, the first distance may be dynamically set corresponding to the average driving speed per unit time. For example, as the average driving speed increases, the first distance may increase.

[0138] When the current driving speed is greater than the speed corresponding to the current position on the first glide line as a basic setting, referred to as the first glide line speed, the fuel cell system controller 420 can adjust the motor baseline 910 used to determine whether to enter the FC STOP state upward as shown by the reference numeral 920.

[0139] When the motor torque measured at the current driving speed is below the upwardly adjusted motor torque baseline 920 , the vehicle may enter the FC STOP state. Since the motor torque baseline is adjusted upward, the FC STOP state entry time point may be advanced as shown by reference numerals 930 and 931 .

[0140] In addition, when the FC STOP state entering time point is advanced, as shown by reference numerals 940 and 941 , the air compressor stop time point may be advanced.

[0141] When the air compressor is quickly stopped by quickly entering the FC STOP state, the energy consumption of the fuel cell system such as accessories can be reduced, thereby improving fuel efficiency. In addition, the durability of the fuel cell system can be improved by minimizing the driving time of accessories.

[0142] The process of the method or algorithm described in the embodiments of the present disclosure may be directly implemented as hardware, software modules, or a combination of hardware and software modules executed by the processor 1100. The software module may reside in a storage medium (i.e., memory and / or storage device) such as RAM, flash memory, ROM, EPROM, EEPROM, registers, hard disk, removable disk, or CD-ROM.

[0143] An exemplary storage medium is coupled to a processor, and the processor can read information from the storage medium and can write information to the storage medium. In another method, the storage medium can be integrated with the processor. The processor and the storage medium can reside in an application specific integrated circuit (ASIC). The ASIC can reside in a user terminal. In another method, the processor and the storage medium can reside in a user terminal as separate components.

[0144] According to the present disclosure, a fuel efficiency improvement method of a fuel cell electric vehicle using navigation information and a fuel efficiency improvement device and system of a fuel cell electric vehicle are provided.

[0145] In addition, according to the present disclosure, a method for improving the fuel efficiency of a fuel cell electric vehicle using navigation information, as well as a fuel cell electric vehicle fuel efficiency improving device and system are provided, which can quickly and accurately enter a fuel cell stop state by predicting vehicle deceleration in advance based on map information obtained from navigation, thereby improving fuel efficiency by reducing the energy consumed by fuel cell accessories and the amount of hydrogen supplied.

[0146] In addition, according to the present disclosure, the durability of the fuel cell stack can be increased by actively entering a fuel cell stop state to minimize the operating time of the fuel cell stack relative to the vehicle mileage.

[0147] In addition, various effects directly or indirectly understood by the present disclosure can be provided.

[0148] The above description is a simple example of the technical spirit of the present disclosure, and those skilled in the art to which the present disclosure belongs may make various changes and modifications to the present disclosure without departing from the essential characteristics of the present disclosure.

[0149] Therefore, the embodiments disclosed in the present disclosure do not limit the technical purpose of the present disclosure but are exemplary, and the scope of the technical purpose of the present disclosure is not limited by the embodiments of the present disclosure. The scope of the present disclosure should be interpreted by the claims, and it should be understood that all technical purposes within the equivalent scope fall within the scope of the present disclosure.

Claims

1. A method for improving the fuel efficiency of a fuel cell electric vehicle, comprising: Collect navigation information and vehicle speed information; calculating a glide line when a specific event point is sensed based on the navigation information, the glide line being a speed curve for performing glide descent so that the speed of the vehicle becomes a target speed at the event point where deceleration occurs; Determine whether to slow down by comparing the current driving speed with the taxiway speed corresponding to the current position; as well as When deceleration is required as a result of the determination, the criteria for determining whether to enter the fuel cell stop state, i.e., the FC STOP state, are changed. Wherein, changing the standard includes: when the current driving speed is equal to or greater than the coasting line speed, adjusting the motor torque reference value for entering the FC STOP state to a specific level greater than the current motor torque reference value.

2. The method according to claim 1, wherein: The glide line is calculated based on a glide descent constant value which is a unique value of a vehicle and a weight of the vehicle.

3. The method according to claim 1, wherein: The navigation information includes: Gradient information as the inclination of the road from the current position to the event point; and The distance information from the current location to the event point.

4. The method according to claim 3, further comprising: The calculated glide line is corrected by using the slope information and the distance information.

5. The method according to claim 2, wherein: Determining whether deceleration is necessary includes: When the current driving speed is equal to or greater than the taxiing line speed, determining that deceleration is required; and When the current driving speed is less than the taxiing line speed, it is determined that deceleration is not required.

6. The method according to claim 5, wherein: Changing the standard includes: entering the FC STOP state when the current motor torque is less than the motor torque reference value.

7. The method according to claim 1, wherein: receiving the navigation information from the navigation device via a controller area network (CAN) communication, and The vehicle speed information is received from a driving controller through the CAN communication.

8. The method according to claim 7, wherein: The driving controller includes at least one of a brake controller, an accelerator controller, and a wheel sensor.

9. The method according to claim 1, wherein: The navigation information and the vehicle speed information are received from a navigation device through CAN communication.

10. The method according to claim 1, wherein: The event point includes at least one of a road branch starting point, a highway toll station entrance / exit point, a speed bump, a speed camera location, a speed limit change point, a safe driving section starting point, a congested section starting point, a sharp turn section starting point and a right turn point.

11. A fuel cell system controller for controlling a fuel cell system, comprising: a communication device to collect navigation information and vehicle speed information; a calculation device that calculates a glide line when a specific event point is sensed based on the navigation information, the glide line being a speed curve for performing glide descent so that the speed of the vehicle becomes a target speed at the event point where deceleration occurs; a judging device for judging whether deceleration is required by comparing the current travel speed with the glide line speed corresponding to the current position; as well as A changing device changes the criteria for determining whether to enter a fuel cell stop, i.e., FCSTOP, state when deceleration is required as a result of the judgment, wherein the changing device is configured to adjust the motor torque reference value for entering the FC STOP state to a specific level greater than the current motor torque reference value when the current driving speed is equal to or greater than the coasting line speed.

12. The fuel cell system controller according to claim 11, wherein: The glide line is calculated based on a glide descent constant value which is a unique value of a vehicle and a weight of the vehicle.

13. The fuel cell system controller according to claim 11, wherein: The navigation information includes: Gradient information as the inclination of the road from the current position to the event point; and The distance information from the current location to the event point.

14. The fuel cell system controller according to claim 13, further comprising: A correction device corrects the calculated glide line by using the slope information and the distance information.

15. The fuel cell system controller according to claim 12, wherein: The judging device is configured to: When the current travel speed is equal to or greater than the glide line speed, it is determined that deceleration is required, and when the current travel speed is less than the glide line speed, it is determined that deceleration is not required.

16. The fuel cell system controller according to claim 15, wherein: The changing device is configured to adjust the motor torque reference value to the specific level so as to enter the FC STOP state to stop the air compressor of the fuel cell system when a current motor torque is less than the motor torque reference value.

17. The fuel cell system controller according to claim 11, wherein: receiving the navigation information from the navigation device via a controller area network (CAN) communication, and The vehicle speed information is received from a driving controller through the CAN communication.

18. The fuel cell system controller according to claim 17, wherein: The driving controller includes at least one of a brake controller, an accelerator controller, and a wheel sensor.

19. The fuel cell system controller according to claim 11, wherein: The navigation information and the vehicle speed information are received from a navigation device through CAN communication.

20. The fuel cell system controller according to claim 11, wherein: The event point includes at least one of a road branch starting point, an expressway toll station entrance and exit point, a speed bump, a speed camera location, a speed limit change point, a safe driving section starting point, a congested section starting point, a sharp turn section starting point, and a right turn point.

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