KR102422328B1 - Fuel cell system and vehicle comprising the same, control method for fuel cell system - Google Patents

Abstract

The present invention proposes a fuel cell system, a vehicle including the same, and a control method of the fuel cell system.
To this end, according to a fuel cell system, a vehicle including the same, and a control method of a fuel cell system according to an aspect of the present invention, when an abnormal voltage is generated in the fuel cell while the fuel cell system is operating, an immediate emergency purging is not performed, and the minimum By deriving the maximum available current and the maximum available current of the auxiliary output unit according to the performance of the voltage cell and avoiding the emergency purge within the range that allows the maximum output described in the system specification, the system required performance can be satisfied and fuel efficiency can be improved. be able to

Description

A fuel cell system, a vehicle including the same, and a control method of a fuel cell system

The present invention relates to a fuel cell system, a vehicle including the same, and a control method of the fuel cell system.

In general, a fuel cell is a power generation device that generates electric energy by electrochemically reacting a fuel and an oxidizing agent. Typically, electric energy may be generated by using hydrogen as a fuel and oxygen as an oxidizing agent.

The basic structure of a fuel cell is based on a unit cell in which an anode (hydrogen electrode) and an anode (oxygen electrode) form an electrode with an electrolyte interposed therebetween. When oxygen and hydrogen are supplied to the unit cell, electricity is generated by electrolysis and reverse reaction of water through the electrolyte. In general, since the voltage generated by one such unit cell is not high enough to be usefully used, the fuel cell is configured in the form of a stack in which several unit cells are connected in series.

In addition, in the fuel cell, as the amount of impurities such as nitrogen, water, and water vapor flowing over to the hydrogen electrode through the electrolyte inside the stack increases, the amount of hydrogen in the hydrogen electrode decreases and the reaction efficiency decreases. Therefore, hydrogen purge is performed according to a predetermined time point. Hydrogen purge is to periodically discharge hydrogen from the hydrogen electrode by installing a purge valve in the line on the outlet side of the hydrogen electrode of the fuel cell stack, thereby simultaneously discharging and removing impurities such as nitrogen and water from the fuel cell stack, and increasing the hydrogen utilization rate.

When an abnormal voltage is generated during operation in a fuel cell system using such a fuel cell as a power source, an emergency purge is performed to prevent reverse voltage.

However, in this case, since hydrogen that is purged with water from the hydrogen electrode is discharged along the hydrogen purge line, unnecessary hydrogen consumption occurs and fuel efficiency is lowered.

One aspect of the present invention provides a fuel cell system capable of improving fuel efficiency by maximally avoiding an emergency purge while satisfying a user's required output when an abnormal voltage is generated in a fuel cell, a vehicle including the same, and a control method of the fuel cell system. to provide.

A fuel cell system according to an aspect of the present invention includes: a fuel cell; a voltage monitoring unit that measures the stack voltage of the fuel cell; and a control unit that determines whether the voltage of the fuel cell is abnormal and controls the emergency purge to be performed, wherein the control unit receives the stack voltage of the fuel cell and determines whether the voltage of the fuel cell is abnormal, and the abnormal voltage in the fuel cell If it is determined that it has occurred, it is decided whether to perform an emergency purge.

The voltage monitoring unit measures voltages of all cells of the fuel cell in real time.

The control unit may further include a voltage determination unit configured to receive the measured voltages of all cells of the fuel cell and determine whether the voltage of the fuel cell is abnormal or not, and the voltage determination unit may include: The voltage state of the fuel cell is determined by comparing the cell voltage Vmin with a predetermined abnormal voltage Vemg.

When the minimum cell voltage Vmin is less than the abnormal voltage Vemg, the voltage determination unit determines that an abnormal voltage has occurred in the fuel cell.

In addition, the fuel cell system according to an aspect of the present invention further includes an auxiliary output unit that provides an output necessary for driving a motor in addition to the fuel cell, and the auxiliary output unit includes a high voltage battery or a supercapacitor.

The control unit may include: a first current calculator configured to calculate a maximum available current Imin,avail of a cell with a minimum voltage when it is determined that an abnormal voltage has occurred in one or more cells among all cells of the fuel cell; It further includes; a second current calculation unit for calculating the maximum available current (Ibat, available) of the auxiliary output unit.

The maximum available current (Imin,avail) of the minimum voltage cell is calculated by [Equation 1] by adding a constant current value (ΔI) based on the current value (Imin) at which the minimum cell voltage (Vmin) occurs, and [Equation 1] In [Equation 3], the constant current value (ΔI) is defined by [Equation 3], s is the voltage/current slope at the point (Imin,Vmin), ΔV = Vemg - Vmin,sys, and Vmin,sys is the minimum allowable voltage of the fuel cell system, and Vemg is the abnormal voltage.

Imin,avail = Imin + ΔI … … … [Formula 1]

ΔI = s × ΔV … … … [Equation 3]

The maximum available current (Ibat,avail) of the auxiliary output unit is calculated by [Equation 4] using the characteristics of the high voltage battery, and Pmax is the maximum power of the battery in [Equation 4].

Ibat,avail = Pmax / Vbat … … … [Equation 4]

In addition, the fuel cell system according to an aspect of the present invention further includes a purge valve that is periodically opened to remove impurities inside the fuel cell, and the control unit includes a maximum available current (Imin,avail) of a minimum voltage cell. and the sum of the maximum available currents (Ibat,avail) of the auxiliary output unit are compared with a predetermined maximum required current (Imax) to determine whether to perform the emergency purge.

When the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit is less than the maximum required current (Imax), the control unit opens the purge valve to perform an emergency purge do.

The control unit, if the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit is not less than the maximum required current (Imax), the maximum available current (Imin) of the minimum voltage cell ,avail) value to limit the current of the fuel cell.

In addition, a fuel cell system according to another aspect of the present invention includes: a fuel cell; an auxiliary output unit providing an output necessary for driving a motor in addition to the fuel cell; a voltage monitoring unit that measures voltages of all cells of the fuel cell; and a controller configured to determine whether the voltage of the fuel cell is abnormal and control the emergency purge to be performed, wherein the controller includes a voltage determining unit configured to receive the measured voltages of all cells of the fuel cell and determine whether the voltage of the fuel cell is abnormal. ; a first current calculator configured to calculate a maximum available current (Imin,avail) of a cell having a minimum voltage when it is determined that an abnormal voltage has occurred in one or more cells among all cells of the fuel cell; It further includes; a second current calculation unit for calculating the maximum available current (Ibat, available) of the auxiliary output unit.

In addition, a vehicle according to an aspect of the present invention includes a fuel cell system; and a driving unit that receives power from the fuel cell system and generates rotational force, wherein the fuel cell system includes: a fuel cell; an auxiliary output unit providing an output necessary for the driving unit in addition to the fuel cell; a voltage monitoring unit that measures voltages of all cells of the fuel cell; and a control unit that determines whether the voltage of the fuel cell is abnormal and controls the emergency purge to be performed, wherein the control unit receives voltages of all cells of the fuel cell, determines whether the voltage of the fuel cell is abnormal, and is abnormal in the fuel cell. When it is determined that a voltage has occurred, it is decided whether to perform an emergency purge.

In addition, a vehicle according to another aspect of the present invention includes a fuel cell; an auxiliary output unit providing an output necessary for driving a motor in addition to the fuel cell; a voltage monitoring unit that measures voltages of all cells of the fuel cell; and a controller configured to determine whether the voltage of the fuel cell is abnormal and control the emergency purge to be performed, wherein the controller includes a voltage determining unit configured to receive the measured voltages of all cells of the fuel cell and determine whether the voltage of the fuel cell is abnormal. ; a first current calculator configured to calculate a maximum available current (Imin,avail) of a cell having a minimum voltage when it is determined that an abnormal voltage has occurred in one or more cells among all cells of the fuel cell; It further includes; a second current calculation unit for calculating the maximum available current (Ibat, available) of the auxiliary output unit.

Another aspect of the present invention provides a control method of a fuel cell system including a fuel cell and an auxiliary output unit serving as an auxiliary power source in addition to the fuel cell, comprising: measuring voltages of all cells of the fuel cell; monitoring a minimum cell voltage (Vmin) of a cell having a minimum voltage among all cells of the fuel cell; comparing the minimum cell voltage Vmin with a predetermined abnormal voltage Vemg to determine whether a voltage of the fuel cell is abnormal; When the minimum cell voltage Vmin is less than the abnormal voltage Vemg, determining whether to perform the emergency purging by determining that an abnormal voltage has occurred in the fuel cell; and determining whether to perform the emergency purging, Calculate the maximum available current (Imin,avail) of the minimum voltage cell, the maximum available current (Ibat,avail) of the auxiliary output, the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current of the auxiliary output By comparing the sum of (Ibat,avail) with the determined maximum required current (Imax), it is determined whether emergency purge is performed.

According to the fuel cell system, the vehicle including the same, and the control method of the fuel cell system according to an aspect of the present invention, when an abnormal voltage is generated in the fuel cell while the fuel cell system is being operated, an immediate emergency purge is not performed and the minimum voltage cell By deriving the maximum available current and the maximum available current of the auxiliary output unit according to the performance of do.

1 is a view showing the exterior of a vehicle equipped with a fuel cell system according to an embodiment of the present invention.
2 is a diagram illustrating a configuration of a vehicle on which a fuel cell system according to an embodiment of the present invention is mounted.
3 is a control configuration diagram of a fuel cell system according to an embodiment of the present invention.
4 is a view for explaining a principle of generating electricity in a unit cell constituting a fuel cell stack of a fuel cell system according to an embodiment of the present invention.
5 is a block diagram of a control unit for performing an emergency purge of a fuel cell system according to an embodiment of the present invention.
6 is a flowchart illustrating an emergency purge control method of a fuel cell system according to an embodiment of the present invention.
7 is a graph illustrating a calculation method for deriving a maximum available current of a minimum voltage cell in a fuel cell system according to an embodiment of the present invention.
8 is a graph illustrating a calculation method for deriving a maximum available current of an auxiliary output unit in a fuel cell system according to an embodiment of the present invention.

The configuration shown in the embodiments and drawings described in this specification is a preferred example of the disclosed invention, and there may be various modifications that can replace the embodiments and drawings of the present specification at the time of filing of the present application.

In addition, the same reference numbers or reference numerals in each drawing in the present specification indicate parts or components that perform substantially the same functions.

In addition, the terms used herein are used to describe the embodiments, and are not intended to limit and/or limit the disclosed invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as "comprises", "comprises" or "have" are intended to designate that the features, numbers, steps, operations, components, parts, or combinations thereof described in the specification exist, but one It does not preclude in advance the possibility of the presence or addition of other features or numbers, steps, actions, components, parts, or combinations thereof, or other features.

In addition, terms including an ordinal number such as "first", "second", etc. used herein may be used to describe various elements, but the elements are not limited by the terms, and the terms are It is used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, a first component may be referred to as a second component, and similarly, a second component may also be referred to as a first component. The term “and/or” includes a combination of a plurality of related listed items or any of a plurality of related listed items.

Hereinafter, an embodiment of the disclosed fuel cell system, a vehicle including the same, and a control method of the fuel cell system will be described in detail with reference to the accompanying drawings.

1 is a view showing the exterior of a vehicle equipped with a fuel cell system according to an embodiment of the present invention, and FIG. 2 is a view showing the configuration of a vehicle equipped with a fuel cell system according to an embodiment of the present invention to be.

1 and 2 , a vehicle 1 according to an embodiment of the present invention includes wheels 51 and 52 for moving the vehicle 100 , a driving device 60 for rotating the wheels 51 and 52 , and the vehicle. (1) a door 71 that shields the inside from the outside, a windshield 30 that provides a view of the front of the vehicle 1 to a driver inside the vehicle 1, and a front glass 30 that provides a view of the rear of the vehicle 1 to the driver It may include side mirrors 81 and 82 .

The windshield 30 is provided on the upper front side of the vehicle 1 so that the driver can obtain visual information on the front side of the vehicle 1 , and may be implemented with windshield glass.

The wheels 51 and 52 include a front wheel 51 provided at the front of the vehicle and a rear wheel 52 provided at the rear of the vehicle, and the driving unit 60 includes a front wheel ( 51) or the rear wheel 52 may be provided with a rotational force. 1 and 2 , a front wheel driving method for providing rotational force to the front wheel 51 is applied and illustrated.

Existing vehicles employ an internal combustion engine that generates rotational force by burning fossil fuels such as petroleum as the driving unit 60 , but the driving unit 60 of the vehicle 1 according to an embodiment is powered from the fuel cell system 100 . It is possible to employ a motor (motor) that receives the supply to generate a rotational force.

In addition, the side mirrors 81 and 82 include a left side mirror 81 provided on the left side of the vehicle 1 and a right side mirror 82 provided on the right side of the vehicle 1 , and the driver inside the vehicle 1 is the vehicle ( 1 ). 1) to obtain side and rear visual information.

The fuel cell system 100 receives fuel from the fuel tank 10 in which the fuel is stored, and receives air from the air supply 20 to generate electric energy. The generated electrical energy is transmitted to the driving unit 60 . For example, electrical energy generated in the fuel cell system 100 may be converted from DC power to AC power while passing through the converter 30 and transmitted to the driving unit 60 . The converter 30 may include a booster for boosting voltage and an inverter for converting DC power into AC power.

When the fuel cell system 100 uses hydrogen as a fuel, water vapor (H2O) generated by the reaction of hydrogen and oxygen is not exhaust gas such as carbon monoxide or nitrogen oxides generated when using conventional fossil fuels. can be emitted.

3 is a control configuration diagram of a fuel cell system according to an embodiment of the present invention, and FIG. 4 is a diagram illustrating a principle of generating electricity of a unit cell constituting a fuel cell stack of a fuel cell system according to an embodiment of the present invention. It is a drawing.

In FIG. 3 , a fuel cell system 100 according to an embodiment of the present invention includes a fuel cell 110 , a voltage monitoring unit 120 , an auxiliary output unit 130 , an output adjusting unit 140 , and a purge valve 150 . and a control unit 160 .

When fuel (hydrogen) is supplied through the fuel tank 10 and oxygen is supplied through the air supply 20 , the fuel cell 110 generates electric energy by a reaction between hydrogen and oxygen.

As shown in FIG. 4 , the fuel cell 110 may be formed by stacking a plurality of unit cells 110 - 1 , for example, several to hundreds of stacked units. Referring to FIG. 4 , the unit cells 110 - In 1), the process of generating electrical energy will be described.

In FIG. 4 , when oxygen is supplied to the positive electrode 111 of the unit cell 110 - 1 and hydrogen is supplied to the negative electrode 113 , the reverse electrolysis reaction of water proceeds to generate electrical energy.

Specifically, when hydrogen molecules (H2) are supplied to the cathode 113, the supplied hydrogen molecules (H2) may be separated into hydrogen ions (H+) and electrons (e−) by a catalyst. Hydrogen ions (H+) may pass through the electrolyte 112 , whereas electrons (e−) may not pass through the electrolyte 112 . Instead, electrons e- may flow into the external circuit 114 to generate direct current electricity (DC).

When molecular oxygen (O2) is supplied to the anode 111, the supplied oxygen molecules (O2) combine with hydrogen ions (H+) and electrons (e-) that have passed through the electrolyte 122 to generate water (H2O) and heat. can cause

Such unit cells 110 - 1 may be included in one MEA (Membrane Electrode Assembly), and a plurality of MEAs may be connected in series to each other to constitute one fuel cell 110 stack. Accordingly, the fuel cell 110 stack may generate a higher voltage than that of one unit cell 110 - 1 .

In FIG. 3 , the fuel tank 10 and the air supply unit 20 are excluded from the configuration of the fuel cell system 100 , but the fuel tank 10 or the air supply unit 20 is included in the fuel cell system 100 according to design matters. Of course, it is also possible to include it in the configuration.

Meanwhile, in the fuel cell system 100 of FIG. 3 , hydrogen may be employed as a fuel supplied to the fuel cell 110 . Therefore, hydrogen itself may be stored in the fuel tank 10, but in some cases, hydrocarbon-based fuel such as methanol, gasoline, LPG, etc. is stored in the fuel tank 10, and the fuel tank 10 and the fuel supply valve ( It is also possible to provide a reformer (reformer) for generating hydrogen by decomposing hydrocarbon-based fuel between the (not shown). As long as hydrogen is supplied to the fuel cell 110 through the fuel supply valve, there is no limitation on what fuel or hydrogen source is stored in the fuel tank 10 .

In FIG. 3 , the voltage monitoring unit 120 is a stack voltage monitor (SVM) that monitors the stack voltage of the fuel cell 110 , that is, the voltage of all unit cells 110 - 1 in real time.

The voltage monitoring unit 120 measures the voltages of all the unit cells 110 - 1 of the fuel cell 110 while the fuel cell system 100 is operating and transmits it to the control unit 160 .

The auxiliary output unit 130 is an auxiliary power source for providing an output (power) necessary for driving a motor in addition to the fuel cell 110 which is the main power source of the vehicle 1 , and is a power storage means, for example, a high-voltage battery 131 capable of charging/discharging. Alternatively, a supercapacitor (supercap) may be applied.

The high voltage battery 131 is an auxiliary battery separate from the fuel cell 110 and may be provided to provide power of a high voltage (eg, 180V). The high-voltage battery 131 is a large-capacity lithium-ion battery corresponding to the existing plug-in, and is a high-voltage battery ( 131) alone, the vehicle 1 may be operated. Accordingly, in addition to the fuel cell 110 using hydrogen as a power source for driving the vehicle 1 on which the fuel cell system 100 is mounted, a secondary source such as household electricity is directly charged to the high voltage battery 131 to the vehicle ( 1) The power source for driving can be diversified. The high voltage battery 131 may be charged by a charging unit (not shown) using an external power source.

The auxiliary output unit 130 may generate output (power) together with the fuel cell 110 to satisfy a user's required output or absorb energy generated from the fuel cell 110 or the driving unit 60 .

The output adjusting unit 140 may adjust an output (power) level between the fuel cell 110 and the auxiliary output unit 130 .

The purge valve 150 is an electronic control valve that is periodically opened at a predetermined time according to a control command of the controller 160 to remove impurities inside the fuel cell 110 . When the purge valve 150 is opened, the fuel cell (110) It is possible to discharge and remove impurities such as nitrogen or water inside.

The purge valve 150 may employ one of various types of automatically controlled valves. For example, the purge valve 150 may be implemented as a solenoid valve using an electromagnet.

The control unit 160 includes a driving unit 160 , a voltage monitoring unit 120 , an auxiliary output unit 130 , an output adjusting unit 140 and It may communicate with a purge valve 150 .

The controller 160 may use a controller area network (CAN) network of the vehicle 1 . The CAN network refers to a network system used for data transmission and control between electronic devices (Electronic Control Unit, ECU) of the vehicle 1 . Specifically, the CAN network transmits data through a two-stranded data wire that is twisted or shielded by a sheath. CAN operates according to the multi-master principle in which multiple ECUs perform master functions in a master/slave system. In addition, the control unit 160 may communicate through an in-vehicle wired network such as LIN (Local Interconnect Network) and MOST (Media Oriented System Transport) of the vehicle 1 or a wireless network such as Bluetooth.

In addition, the controller 160 is a microprocessor that controls overall operations of the fuel cell system 100 , and may control operations of various modules and devices built in the fuel cell system 100 . According to an embodiment, the controller 160 may be operated by a processor built into the fuel cell system 100 , and generates a control signal for controlling various modules and devices built in the fuel cell system 100 . Thus, the operation of each component can be controlled.

In addition, the control unit 160 includes a memory in which a program and various data related thereto for performing operations to be described above and below, a processor for executing a program stored in the memory, a hydraulic control unit (HCU), a microcontroller (MCU), which is a hydraulic control unit. unit) and the like. Also, the controller 160 may be integrated in a system on chip (SOC) built into the vehicle 1 and may be operated by a processor. However, since there is not only one system-on-chip embedded in the vehicle 1, but may be plural, integration is not limited to only one system-on-chip.

The control unit 160 is a memory type (flash memory type), a hard disk type (hard disk type), a multimedia card micro type (multimedia card micro type), card type memory (for example, SD or XD memory, etc.), RAM ( Random Access Memory: RAM), SRAM (Static Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), PROM (Programmable Read-Only Memory), magnetic memory, magnetic disk , may be implemented through at least one type of storage medium among optical disks. However, the present invention is not limited thereto, and may be implemented in any other form known in the art.

In addition, the control unit 160 according to an embodiment of the present invention determines whether the voltage of the fuel cell 110 is abnormal using the voltages of all unit cells 110-1 monitored by the voltage monitoring unit 120, Implement techniques for maximally avoiding emergency purges. This will be described with reference to FIG. 5 .

5 is a block diagram of a control unit for performing an emergency purge of a fuel cell system according to an embodiment of the present invention.

In FIG. 5 , the control unit 160 receives the voltages of all cells 110 - 1 of the fuel cell 110 measured by the voltage monitoring unit 120 , and determines whether the voltage of the fuel cell 110 is abnormal or not. When it is determined that an abnormal voltage has occurred in one or more cells 110-1 among all cells 110-1 of the fuel cell 110 and at 161, the maximum available current of the minimum voltage cell 110-1 is derived. and a first current calculation unit 162 for generating the maximum available current of the auxiliary output unit 130 , and a second current calculation unit 163 for deriving the maximum available current of the auxiliary output unit 130 .

Accordingly, when it is determined that an abnormal voltage is generated in one or more cells 110 - 1 among all cells 110 - 1 of the fuel cell 110 , the controller 160 determines the maximum available current of the minimum voltage cell 110 - 1 . Whether the emergency purge is avoided may be controlled by determining whether the sum of the and the maximum available current of the auxiliary output unit 130 is less than a predetermined maximum current. The abnormal voltage is a voltage at which the voltage per cell 110 - 1 of the stack of the fuel cell 110 is lowered below the available voltage range per cell 110 - 1 . That is, a voltage at which the voltage per cell 110 - 1 is lower than a predetermined voltage compared to a normal operating voltage is referred to as an abnormal voltage. For example, if the maximum power of the fuel cell 110 stack is 80W based on the 100W power, the fuel cell 110 stack is deteriorated and the voltage per cell 110-1 is lowered.

As a result of the determination, if the sum of the maximum available current of the minimum voltage cell 110 - 1 and the maximum available current of the auxiliary output unit 130 is less than the maximum current, the controller 160 opens the purge valve 150 to make an emergency purge can be performed.

As a result of the determination, if the sum of the maximum available current of the minimum voltage cell 110 - 1 and the maximum available current of the auxiliary output unit 130 is not less than the maximum current, the control unit 160 prevents reverse voltage of the fuel cell 110 . To this end, the current limit of the fuel cell 110 may be performed with the maximum available current of the minimum voltage cell 110 - 1 .

Although the voltage monitoring unit 120 is excluded from the configuration of the control unit 160 in FIG. 5 , the voltage monitoring unit 120 may be included in the configuration of the control unit 160 according to design matters.

Hereinafter, an operation process and effects of a fuel cell system, a vehicle including the same, and a method for controlling a fuel cell system according to an embodiment of the present invention will be described.

6 is an operation flowchart illustrating an emergency purging control method of a fuel cell system according to an embodiment of the present invention, and FIG. 7 is a maximum available current of a minimum voltage cell in the fuel cell system according to an embodiment of the present invention. 8 is a graph illustrating a calculation method for deriving the maximum available current of the auxiliary output unit in the fuel cell system according to an embodiment of the present invention.

6 illustrates a control process performed by the control unit 160 when the fuel cell system 100 is operating.

In FIG. 6 , the voltage monitoring unit 120 measures the voltages of all cells 110 - 1 of the fuel cell 110 to obtain the minimum cell voltage (Vmin) of the cells 110 - 1 (minimum voltage cells) having the minimum voltage. to monitor (200).

The minimum cell voltage Vmin monitored by the voltage monitoring unit 120 is transmitted to the control unit 160 .

Accordingly, the controller 160 compares the minimum cell voltage Vmin with the stored abnormal voltage Vemg (a reference value for determining the normal state of the fuel cell voltage) to determine the voltage state of the fuel cell 110, It is determined whether the voltage Vmin is less than the abnormal voltage Vemg ( 202 ).

If it is determined in step 202 that the minimum cell voltage Vmin is not less than the abnormal voltage Vemg, the controller 160 determines that the voltage state of the fuel cell 110 is normal, and feeds back to step 200 to perform subsequent operations. proceed

Meanwhile, if it is determined in step 202 that the minimum cell voltage Vmin is less than the abnormal voltage Vemg, the controller 160 determines that the voltage state of the fuel cell 110 is abnormal, and determines whether to perform an emergency purging. Proceed to the information derivation step for

When it is determined that an abnormal voltage has occurred in one or more cells 110 - 1 among all cells 110 - 1 of the fuel cell 110 , the controller 160 determines the maximum available current Imin of the minimum voltage cell 110 - 1 . , available) is calculated (204).

The maximum available current Imin,avail of the minimum voltage cell 110 - 1 may be calculated using the graph shown in FIG. 7 . When the voltage Vmin of the cell 110-1 having the minimum voltage among all the cells 110-1 of the fuel cell 110 is less than the abnormal voltage Vemg, the current value Imin at which the voltage is generated is the reference. It can be calculated by [Equation 1] as follows by adding a constant current value (ΔI) to

Imin,avail = Imin + ΔI … … … [Formula 1]

In this case, ΔI can be obtained in the following way.

First, the voltage/current slope at the point (Imin, Vmin) can be obtained by [Equation 2].

s = -dv / di … … … [Equation 2]

Next, based on the S value, ΔI for the difference between the minimum allowable voltage (Vmin,sys) and the abnormal voltage (Vemg)dml of the fuel cell system 100 can be obtained by [Equation 3].

ΔI = s × ΔV … … … [Equation 3]

In [Equation 3], ΔV = Vemg - Vmin,sys.

In FIG. 6 , when it is determined that an abnormal voltage has occurred in one or more cells 110 - 1 among all cells 110 - 1 of the fuel cell 110 , the control unit 160 uses the second current calculation unit 163 . Thus, the maximum available current Ibat,avail of the auxiliary output unit 130 is calculated (206).

The maximum available current Ibat,avail of the auxiliary output unit 130 may be calculated using the graph shown in FIG. 8 . When the high voltage battery 131 is used as the auxiliary output unit 130, the maximum available current Ibat,avail of the auxiliary output unit 130 can be calculated using the battery characteristic graph of FIG. 8 as in [Equation 4]. have.

Ibat,avail = Pmax / Vbat … … … [Equation 4]

Subsequently, the controller 160 determines the maximum available current Imin,avail of the minimum voltage cell 110-1 and the auxiliary output unit 130 based on the maximum required current Imax determined by the specification of the fuel cell system 100 . ), it is determined whether the sum of the maximum available currents Ibat,avail is smaller than the maximum required current Imax (208).

As a result of the determination in step 208, the sum of the maximum available current Imin,avail of the minimum voltage cell 110-1 and the maximum available current Ibat,avail of the auxiliary output unit 130 is less than the maximum required current Imax , the controller 160 opens the purge valve 150 to perform an emergency purge ( 210 ).

On the other hand, as a result of the determination in step 208, the sum of the maximum available current Imin,avail of the minimum voltage cell 110-1 and the maximum available current Ibat,avail of the auxiliary output unit 130 is the maximum required current Imax Otherwise, the controller 160 limits the current of the fuel cell 110 to the maximum available current Imin,avail of the minimum voltage cell 110-1 to prevent reverse voltage of the fuel cell 110 ( 212).

Those of ordinary skill in the art related to the exemplary embodiments of the present invention will understand that it may be implemented in a modified form without departing from the essential characteristics of the description. Therefore, the disclosed methods are to be considered in an illustrative and not a restrictive sense. The scope of the present invention is indicated in the claims rather than the detailed description of the invention, and all differences within the equivalent scope should be construed as being included in the scope of the present invention.

1: vehicle 10: fuel tank
20: air supply 100: fuel cell system
110: fuel cell 120: voltage monitoring unit
130: auxiliary output unit 140: output adjustment unit
150: purge valve 160: control unit
161: voltage determination unit 162: first current calculation unit
163: second current calculation unit

Claims (18)

fuel cell;
a voltage monitoring unit measuring a stack voltage of the fuel cell;
an auxiliary output unit for providing an output necessary for driving a motor in addition to the fuel cell; and
a control unit that determines whether the voltage of the fuel cell is abnormal and controls the emergency purge to be performed;
The auxiliary output unit,
contains a high voltage battery or supercapacitor;
The control unit is
It is determined whether the voltage of the fuel cell is abnormal by receiving the stack voltage of the fuel cell, and when it is determined that an abnormal voltage has occurred in the fuel cell, it is determined whether to perform the emergency purge;
The control unit is
a voltage determination unit configured to receive the measured voltages of all cells of the fuel cell and determine whether the voltage of the fuel cell is abnormal;
The voltage determination unit,
determining the voltage state of the fuel cell by comparing a minimum cell voltage (Vmin) of a cell having a minimum voltage among all cells of the fuel cell with a predetermined abnormal voltage (Vemg);
The control unit is
a first current calculator configured to calculate a maximum available current (Imin,avail) of the minimum voltage cell when it is determined that an abnormal voltage has occurred in one or more cells among all cells of the fuel cell;
A fuel cell system further comprising a; a second current calculation unit for calculating the maximum available current (Ibat, available) of the auxiliary output unit. delete delete delete According to claim 1,
The maximum available current (Imin,avail) of the minimum voltage cell is,
Calculated by [Equation 1] by adding a constant current value (ΔI) based on the current value (Imin) at which the minimum cell voltage (Vmin) is generated, and the constant current value (ΔI) in [Equation 1] is [Equation 3] , and in Equation 3, s is the voltage/current slope at the point (Imin,Vmin), ΔV = Vemg - Vmin,sys, and Vmin,sys is the minimum allowable voltage of the fuel cell system and Vemg is an abnormal voltage.
Imin,avail = Imin + ΔI … … … [Formula 1]
ΔI = s × ΔV … … … [Equation 3] 6. The method of claim 5,
The maximum available current (Ibat,avail) of the auxiliary output is,
The fuel cell system is calculated by [Equation 4] using the characteristics of the high-voltage battery, and in [Equation 4], Pmax is the maximum power of the battery.
Ibat,avail = Pmax / Vbat … … … [Equation 4] 7. The method of claim 6,
Further comprising; a purge valve periodically opened to remove impurities inside the fuel cell;
The control unit is
Fuel for determining whether to perform the emergency purge by comparing the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit with a predetermined maximum required current (Imax) battery system. 8. The method of claim 7,
The control unit is
When the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit is less than the maximum required current (Imax), the purge valve is opened to the emergency purge A fuel cell system that performs 8. The method of claim 7,
The control unit is
If the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit is not less than the maximum required current (Imax), the maximum available current of the minimum voltage cell ( Imin,avail) value to limit the current of the fuel cell. fuel cell;
an auxiliary output unit for providing an output necessary for driving a motor in addition to the fuel cell;
a voltage monitoring unit that measures voltages of all cells of the fuel cell; and
a control unit that determines whether the voltage of the fuel cell is abnormal and controls the emergency purge to be performed;
The control unit is
a voltage determination unit receiving the measured voltages of all cells of the fuel cell and determining whether the voltage of the fuel cell is abnormal;
a first current calculator configured to calculate a maximum available current (Imin,avail) of a cell having a minimum voltage when it is determined that an abnormal voltage has occurred in one or more cells among all cells of the fuel cell;
The fuel cell system further comprising a; a second current calculation unit for calculating the maximum available current (Ibat, available) of the auxiliary output unit. 11. The method of claim 10,
Further comprising; a purge valve periodically opened to remove impurities inside the fuel cell;
The control unit is
When the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit is less than a predetermined maximum required current (Imax), the purge valve is opened to the emergency purge A fuel cell system that performs fuel cell systems; and
Including; a driving unit for generating rotational force by receiving power from the fuel cell system;
The fuel cell system is
fuel cell;
an auxiliary output unit providing an output required for the driving unit in addition to the fuel cell;
a voltage monitoring unit that measures voltages of all cells of the fuel cell; and
a control unit that determines whether the voltage of the fuel cell is abnormal and controls the emergency purge to be performed;
The control unit is
It is determined whether the voltage of the fuel cell is abnormal by receiving the voltages of all cells of the fuel cell, and when it is determined that an abnormal voltage has occurred in the fuel cell, it is determined whether to perform the emergency purge;
The control unit is
a first current calculator configured to calculate a maximum available current (Imin,avail) of a cell having a minimum voltage when it is determined that an abnormal voltage has occurred in one or more cells among all cells of the fuel cell;
A vehicle further comprising a; a second current calculation unit for calculating the maximum available current (Ibat, available) of the auxiliary output unit. fuel cell;
an auxiliary output unit for providing an output necessary for driving a motor in addition to the fuel cell;
a voltage monitoring unit that measures voltages of all cells of the fuel cell; and
a control unit that determines whether the voltage of the fuel cell is abnormal and controls the emergency purge to be performed;
The control unit is
a voltage determination unit receiving the measured voltages of all cells of the fuel cell and determining whether the voltage of the fuel cell is abnormal;
a first current calculator configured to calculate a maximum available current (Imin,avail) of a cell having a minimum voltage when it is determined that an abnormal voltage has occurred in one or more cells among all cells of the fuel cell;
A vehicle equipped with a fuel cell system further comprising a; a second current calculation unit for calculating the maximum available current (Ibat, available) of the auxiliary output unit. In the control method of a fuel cell system including a fuel cell and an auxiliary output unit that is an auxiliary power source in addition to the fuel cell,
measuring voltages of all cells of the fuel cell;
monitoring a minimum cell voltage (Vmin) of a cell having a minimum voltage among all cells of the fuel cell;
determining whether a voltage of the fuel cell is abnormal by comparing the minimum cell voltage Vmin with a predetermined abnormal voltage Vemg;
determining whether to perform an emergency purge by determining that an abnormal voltage has occurred in the fuel cell when the minimum cell voltage Vmin is less than the abnormal voltage Vemg;
Determining whether to perform the emergency purge is,
Calculate the maximum available current (Imin,avail) of the minimum voltage cell, calculate the maximum available current (Ibat,avail) of the auxiliary output unit, the maximum available current (Imin,avail) of the minimum voltage cell and the auxiliary output A control method of a fuel cell system for determining whether to perform the emergency purge by comparing a sum of negative maximum available currents Ibat,avail with a predetermined maximum required current Imax. 15. The method of claim 14,
The maximum available current (Imin,avail) of the minimum voltage cell is,
Calculated by [Equation 1] by adding a constant current value (ΔI) based on the current value (Imin) at which the minimum cell voltage (Vmin) is generated, and the constant current value (ΔI) in [Equation 1] is [Equation 3] , and in Equation 3, s is the voltage/current slope at the point (Imin,Vmin), ΔV = Vemg - Vmin,sys, and Vmin,sys is the minimum allowable voltage of the fuel cell system and Vemg is an abnormal voltage.
Imin,avail = Imin + ΔI … … … [Formula 1]
ΔI = s × ΔV … … … [Equation 3] 16. The method of claim 15,
The maximum available current (Ibat,avail) of the auxiliary output is,
A control method of a fuel cell system, which is calculated by [Equation 4] using the characteristics of a high voltage battery, and Pmax is the maximum power of the battery in [Equation 4].
Ibat,avail = Pmax / Vbat … … … [Equation 4] 17. The method of claim 16,
periodically opening a purge valve for removing impurities in the fuel cell;
When the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit is less than the maximum required current (Imax), the purge valve is opened to the emergency purge A control method of a fuel cell system further comprising; 17. The method of claim 16,
If the sum of the maximum available current (Imin,avail) of the minimum voltage cell and the maximum available current (Ibat,avail) of the auxiliary output unit is not less than the maximum required current (Imax), the maximum available current of the minimum voltage cell ( Imin,avail) value to limit the current of the fuel cell; the control method of the fuel cell system further comprising a.

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