KR20230143888A - Flooding restore control method and system for fuel cell system of vehicle - Google Patents

Abstract

When the fuel cell system is flooded, the rise in back pressure due to blockage of the exhaust port is detected through the change in pressure at the outlet of the air compressor to determine whether there is flooding, and by increasing the rotation speed of the air compressor and performing additional recovery control to relieve back pressure, the fuel cell Introducing a recovery control method and system when a vehicle's fuel cell system is flooded, which prevents damage to the air compressor while resolving system flooding, and can prevent fuel cell system failure due to water inflow in a complete flood situation. do.

Description

Recovery control method and system in case of flooding of vehicle fuel cell system {FLOODING RESTORE CONTROL METHOD AND SYSTEM FOR FUEL CELL SYSTEM OF VEHICLE}

The present invention relates to a recovery control method and system when the fuel cell system of a vehicle is flooded. Specifically, when the fuel cell system is flooded, the increase in back pressure due to exhaust port blockage is detected through the change in pressure at the outlet of the air compressor to determine whether or not it is flooded. It relates to a recovery control method and system in case of flooding of a vehicle's fuel cell system that performs additional recovery control to relieve back pressure while increasing the rotation speed of the air compressor.

Due to recent global oil prices and _CO2 regulations, improving fuel efficiency and eco-friendliness have become key goals in vehicle development. To achieve these goals, automotive companies around the world are focusing on developing technologies for hybrid and electric vehicles.

Unlike gasoline cars, electric vehicles consist of a battery, a power conversion device (inverter), and a motor. The battery is an energy storage device, and the power conversion device is a device that converts the electric energy of the battery into driving power of the vehicle, thereby operating the motor to drive the vehicle.

Meanwhile, electric vehicles can be divided into battery electric vehicles (BEV), which use batteries, and fuel cell electric vehicles (FCEV), which use fuel cells, as described above.

A fuel cell vehicle drives a motor using power generated by a fuel cell, and rotates the axles and wheels using the power to drive. In general, the fuel cell system mounted on a fuel cell vehicle consists of a fuel cell stack that stacks a plurality of fuel cell cells used as a power source, a fuel supply system that supplies hydrogen as a fuel to the fuel cell stack, and an electrochemistry reaction. It includes an air supply system that supplies oxygen, the necessary oxidizing agent, and a water and heat management system that controls the temperature of the fuel cell stack.

In addition, by-products (referring to product water (water), high-temperature heat generated due to electrochemical reactions, etc.) and exhaust gases (referring to unreacted hydrogen and oxygen, etc.) generated during the electrical energy generation process of the fuel cell stack. ), etc., must be equipped with an exhaust system to discharge them to the outside of the vehicle.

This discharge system consists of an outlet and a discharge passage as basic components, a discharge valve, and a discharge pressure detection sensor that detects the pressure of the discharge passage. Here, the exhaust outlet is generally located at the bottom of the floor at the rear of the vehicle body, similar to an internal combustion engine vehicle driven by an engine.

By arranging the outlet in this way, exhaust gases and by-products discharged from the fuel cell can be discharged onto the road surface of the vehicle.

However, when a fuel cell vehicle drives on a flooded road, water existing on the road surface may flow into the outlet, which may block the outlet or create back pressure in the outlet passage.

When back pressure is formed in this way, the operating point of the air compressor, which is a major component of the air supply system, changes. If the fuel cell system is operated for a long time with the operating point of the air compressor changed, the problem of damage to the air compressor occurs.

Additionally, in the case where the entire cross section of the discharge port is blocked (hereinafter referred to as a 'completely flooded situation'), there is a problem that water flows in along the discharge passage, causing a failure of the fuel cell system itself.

Therefore, it is important for fuel cell vehicles to be equipped with a function to detect and resolve vehicle flooding in terms of improving the durability and safety of the vehicle. In particular, we have a climate where rainfall is concentrated during the rainy season of the year, so it is concentrated every year during the rainy season. This is even more important in the case of Korea, where vehicle flooding occurs due to heavy rain.

Accordingly, conventional methods have been applied to prevent flooding by receiving rainfall information based on the vehicle's location information and raising the vehicle's suspension, or to detect flooding by installing a separate water level sensor that can determine the road surface condition.

However, this conventional method only indirectly prevents vehicle flooding, and does not detect and resolve vehicle flooding in real time. Additionally, a separate additional device must be installed to determine flooding conditions, which increases material and production costs. There is a downside to this.

The matters described as background technology above are only for the purpose of improving understanding of the background of the present invention, and should not be taken as acknowledgment that they correspond to prior art already known to those skilled in the art.

KR 10-2019-0135105 A

The present invention was proposed to solve this problem. When the fuel cell system is flooded, the increase in back pressure due to exhaust port blockage is detected through the change in pressure at the outlet of the air compressor to determine whether it is flooded, and by increasing the rotation speed of the air compressor. By implementing additional recovery control to relieve back pressure, it is possible to prevent damage to the air compressor while relieving flooding of the fuel cell system, and to prevent fuel cell system failure due to water inflow in the vehicle in a complete flooding situation. The purpose is to provide a recovery control method and system when a fuel cell system is flooded.

The recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention to achieve the above object includes the steps of determining whether the fuel cell system of the vehicle has been flooded, and if it is determined that the fuel cell system has been flooded, the fuel cell Performing recovery control by controlling the air compressor to increase the rotation speed of the air compressor that supplies air to the cathode side of the stack, and if it is determined that the flooding situation of the fuel cell system has been resolved after increasing the rotation speed of the air compressor, the air compressor It includes the step of controlling the rotation speed to normal.

The step of determining whether the fuel cell system is flooded in the recovery control method when the fuel cell system of a vehicle according to the present invention is flooded includes calculating the target flow rate of air supplied to the fuel cell stack based on the required output, the calculated It may include determining whether the outlet pressure of the air compressor is abnormal based on a preset reference value according to the target flow rate of air, and determining that the fuel cell system is flooded if there is an abnormality in the outlet pressure of the air compressor. .

The step of determining whether the outlet pressure of the air compressor is abnormal based on a reference value prepared in advance according to the target air flow rate calculated in the recovery control method when the fuel cell system of a vehicle according to the present invention is Measuring the outlet pressure and comparing the outlet pressure of the air compressor measured by the air pressure sensor with a preset reference value according to the target flow rate of air calculated based on the required output to determine whether the outlet pressure of the air compressor is abnormal. It can be included.

After calculating the target flow rate of air supplied to the fuel cell stack based on the required output of the recovery control method when the vehicle's fuel cell system is flooded according to the present invention, the flow rate of air flowing from the air flow sensor to the air compressor is It may further include measuring and determining whether the supply air flow rate is insufficient according to the difference between the air flow rate measured by the air flow sensor and the target air flow rate calculated based on the required output.

The step of performing recovery control of the recovery control method when the vehicle's fuel cell system is flooded according to the present invention is to increase the rotation speed of the air compressor and simultaneously build the fuel cell stack based on the air flow rate and required output measured by the air flow sensor. It may be characterized in that the current of the fuel cell stack is limited according to a preset reference value depending on the difference in the target flow rate of air supplied to.

The step of performing recovery control of the recovery control method when the fuel cell system of a vehicle according to the present invention is flooded includes increasing the opening amount of the hydrogen supply valve that supplies hydrogen to the anode side of the fuel cell stack after increasing the rotation speed of the air compressor. It can be characterized as:

The step of performing recovery control of the recovery control method when the fuel cell system of a vehicle according to the present invention is flooded includes an air discharge valve that discharges air that has passed through the cathode of the fuel cell stack to the outside of the vehicle after increasing the rotation speed of the air compressor. It can be characterized by increasing the amount of opening.

After the step of performing recovery control of the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention, the step of determining whether the flooding situation of the fuel cell system has been resolved based on the outlet pressure of the air compressor and the flooding situation being resolved. If not, a step of gradually increasing the opening amount of the air discharge valve may be further included.

The step of gradually increasing the opening amount of the air discharge valve in the flood recovery control method of the fuel cell system of a vehicle according to the present invention includes stopping the operation of the fuel cell system when the opening amount of the air discharge valve is fully opened. It can be characterized.

The step of gradually increasing the opening amount of the air discharge valve in the flood recovery control method of the fuel cell system of a vehicle according to the present invention is that when the opening amount of the air discharge valve is fully opened, the air that has passed through the air compressor is transferred to the fuel cell. It may be characterized by stopping the operation of the fuel cell system after closing the air supply valve that supplies to the cathode of the stack.

The recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention includes an air compressor that supplies air to the cathode of the fuel cell stack and a fuel cell stack that includes a cathode to which air is supplied and an anode to which hydrogen is supplied. It is determined whether the fuel cell system has been flooded, and if it is determined that the fuel cell system has been flooded, recovery control is performed by controlling the air compressor to increase the rotation speed of the air compressor that supplies air to the cathode side of the fuel cell stack. It includes a controller that normally controls the rotation speed of the air compressor when it is determined that the flooding situation of the fuel cell system has been resolved after increasing the rotation speed of the compressor.

The recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention further includes an air flow sensor provided at the inlet of the air compressor to measure the flow rate of air flowing into the air compressor, and the controller measures the flow rate of air flowing into the air compressor based on the required output. The target flow rate of air supplied to the fuel cell stack can be calculated, and whether the supply air flow rate is insufficient can be determined based on the difference between the air flow rate measured by the air flow sensor and the target air flow rate calculated based on the required output.

The recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention further includes an air pressure sensor provided at the outlet of the air compressor to measure the outlet pressure of the air compressor, and the controller controls the fuel cell stack based on the required output. Calculate the target flow rate of air supplied to the air compressor, and compare the outlet pressure of the air compressor measured by the air pressure sensor with a standard value prepared in advance according to the target flow rate of air calculated based on the required output to determine whether the outlet pressure of the air compressor is abnormal. You can judge.

The recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention includes a hydrogen supply valve that supplies hydrogen to the anode side of the fuel cell stack and an air discharge valve that discharges air that has passed through the cathode of the fuel cell stack to the outside of the vehicle. It may further include, and the controller may be characterized in that it controls the hydrogen supply valve and the air discharge valve so that the opening amount of the hydrogen supply valve and the air discharge valve increases after increasing the rotation speed of the air compressor.

The recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention further includes an air supply valve that supplies air that has passed through the air compressor to the cathode of the fuel cell stack, and the controller fully opens the air discharge valve. In this case, the operation of the fuel cell system may be stopped after closing the air supply valve.

According to the flood recovery control method and system of a vehicle fuel cell system of the present invention, the following effects are achieved.

First, by determining whether or not there is flooding from the relationship between the increase in back pressure and the change in pressure at the outlet of the air compressor under flooded conditions of the fuel cell system, the existing fuel cell system can be configured without installing a separate additional device to determine flooding of the fuel cell system. Based on this, it is possible to determine whether or not there is flooding, thereby overcoming conventional technical limitations and preventing additional material cost increases.

Second, by increasing the number of rotations of the air compressor and performing additional recovery control to relieve back pressure, it prevents damage to the air compressor while resolving the flooding situation of the fuel cell system, and prevents fuel cell system failure due to water inflow in a complete flooding situation. can be blocked in advance.

1 is a flowchart of a recovery control method when a fuel cell system of a vehicle is flooded according to an embodiment of the present invention.
Figure 2 is a diagram showing a recovery control system when a fuel cell system of a vehicle is flooded according to an embodiment of the present invention.
Figure 3 is a graph showing the relationship between the flow rate of air sucked into an air compressor and the outlet pressure of the air compressor.
Figure 4 is a graph showing the current limiting ratio of the fuel cell stack according to the difference between the measured flow rate of air and the target flow rate.

Throughout this specification, when a part “includes” a certain component, this means that it may further include other components rather than excluding other components, unless specifically stated to the contrary.

In addition, terms such as first and/or second may be used to describe various components, but these terms are only used to distinguish the component from other components, for example, from the scope of rights according to the concept of the present invention. Without exception, the first component may be referred to as the second component, and similarly the second component may also be referred to as the first component.

Hereinafter, the configuration and operating principles of various embodiments of the disclosed invention will be described in detail with reference to the attached drawings.

Figure 1 is a flowchart of a recovery control method when a vehicle's fuel cell system is flooded according to an embodiment of the present invention, and Figure 2 shows a recovery control system when a vehicle's fuel cell system is flooded according to an embodiment of the present invention. It is a drawing, and FIG. 3 is a graph showing the relationship between the flow rate of air sucked into the air compressor 200 and the outlet pressure of the air compressor 200, and FIG. 4 is a graph showing the fuel cell stack according to the difference between the measured flow rate of air and the target flow rate. This is a graph showing the current limiting ratio of (100).

To help understand the present invention, we will briefly look at the configuration of a general fuel cell system and the conventional control method for controlling it, and explain the distinctive features of each step and component of the present invention.

A general fuel cell system includes a fuel cell stack 100 in which a plurality of fuel cells are stacked, a fuel supply system that supplies hydrogen used as fuel to the anode 120 of the fuel cell stack 100, and a fuel cell system necessary for an electrochemical reaction. It includes an air supply system that supplies oxygen to the cathode 110 of the fuel cell stack 100.

Referring to FIG. 2, the fuel supply system includes a hydrogen tank 400 that stores hydrogen as a fuel, and a hydrogen supply that adjusts the supply flow rate of hydrogen that is depressurized to a certain pressure from the hydrogen tank 400 and supplied to the anode 120. The basic components include a valve 121 and a hydrogen discharge valve 122 that discharges hydrogen after reaction passing through the anode 120.

Continuing, the air supply system includes an air compressor 200 that sucks in external air, an air humidifier 500 that humidifies the air supplied through the air compressor 200, and the air humidifier 500 humidifies the cathode 110. The basic components include an air supply valve 111 that regulates the supply flow rate of air supplied to the and an air discharge valve 112 that discharges air after reaction passing through the cathode 110.

Additionally, the fuel supply system and the air supply system are generally additionally equipped with a flow sensor that measures the flow rate of hydrogen and air, and a pressure sensor that measures the pressure.

For reference, Figure 2 shows that hydrogen flows into the air humidifier 500 after the reaction discharged from the hydrogen discharge valve 122. Since the hydrogen after the reaction contains a small amount of moisture generated as the fuel cell stack 100 operates, this moisture is supplied to the air humidifier 500 for recycling.

Specifically, the air humidifier 500 has a separate membrane formed inside it through which moisture can permeate. Based on this membrane, the inside is called the lumen side, and the outside is called the shell side. The air flowing into the air humidifier 500 from the air compressor 200 passes through the lumen side, and after reaction through the anode 120, the air flows back into the shell side after reaction with hydrogen through the cathode 110. . And after the reaction, a small amount of moisture contained in the hydrogen and air permeates from the shell side to the lumen side to humidify the air flowing into the air humidifier 500 from the air compressor 200.

After the reaction, the hydrogen and air (hereinafter referred to as 'exhaust gas') that are re-introduced to the shell side of the air humidifier 500 flow along the discharge passage connected to the shell side and are discharged to the outside of the vehicle through the exhaust port.

As previously discussed in the background technology, the outlet is generally disposed at the bottom of the floor at the rear of the vehicle body to discharge exhaust gases from the fuel cell onto the road surface of the vehicle.

However, when a fuel cell vehicle drives on a flooded road, water existing on the road flows into the outlet and clogs the outlet or creates back pressure in the outlet passage, changing the operating point of the air compressor 200, and the air compressor ( If the fuel cell system is operated for a long time with the operating point of 200) changed, the air compressor 200 may be damaged.

Additionally, in a completely submerged situation (the entire cross-section of the discharge port is blocked), there is a problem in that water flows backwards along the discharge path, causing a failure of the fuel cell system itself.

Here, the operating point of the air compressor 200 refers to the relationship between the flow rate of air sucked through the air compressor 200 and the pressure (outlet pressure) of air discharged from the air compressor 200, depending on the current operating situation. It means a point at which a decision is made.

In other words, it can be understood to mean any one point on the graph shown in FIG. 3. In FIG. 3, area B refers to the normal operation area of the air compressor 200, area C refers to the surge area, and area D refers to the choking area, which will be described in detail later.

Meanwhile, in the case of conventional technologies that detect or prevent vehicle flooding (using separately mounted water level sensors or suspension lift control based on vehicle location information), they are not methods of directly solving flooding situations, but require separate methods to determine flooding conditions. The disadvantage is that the device must be installed.

Accordingly, the recovery control method and system in case of flooding of the fuel cell system of a vehicle according to the present invention seeks to directly resolve the flooding situation through recovery control based on control that increases the rotation speed of the air compressor 200, as well as , we aim to implement a flooding detection function based on the configuration of the existing fuel cell system without installing additional devices by determining whether or not there is flooding using the change in pressure at the outlet of the air compressor (200) due to the increase in back pressure under flooded conditions.

Hereinafter, with reference to the attached drawings, we will look at the key features of each step and components of the present invention in more detail.

1 is a flowchart of a recovery control method when a fuel cell system of a vehicle is flooded according to an embodiment of the present invention.

Referring to FIG. 1, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention includes the step of determining whether the fuel cell system of the vehicle has been flooded (S100). If it is determined that the fuel cell system has been flooded, After performing recovery control by controlling the air compressor to increase the rotation speed of the air compressor that supplies air to the cathode side of the fuel cell stack (S200) and increasing the rotation speed of the air compressor, it is determined that the flooding situation in the fuel cell system has been resolved. In this case, it includes the step of normally controlling the rotation speed of the air compressor.

In the step of determining whether the fuel cell system of the vehicle is flooded (S100), the flood situation of the fuel cell system is detected by utilizing the change in the outlet pressure of the air compressor 200 due to the increase in back pressure under flooded conditions. The specific operating principle of this step will be described later, and the rotation speed increase control of the air compressor 200 will be examined with reference to FIG. 3.

Figure 3 is a graph showing the relationship between the flow rate of air sucked into the air compressor 200 and the outlet pressure of the air compressor 200.

As mentioned earlier, in FIG. 3, area B refers to the normal operation area of the air compressor 200, area C refers to the surge area, and area D refers to the chalking area.

The surge area refers to an area where the production flow rate of the air compressor 200 is low and a surge phenomenon occurs, and the chalking area refers to an area where the production flow rate of the air compressor 200 is high and a choke phenomenon occurs.

The surge phenomenon can be easily understood as a 'reverse flow phenomenon of compressed air', and the choking phenomenon is a phenomenon that occurs when the speed of fluid in the impeller or diffuser in the air compressor 200 reaches the speed of sound. This refers to a state in which pressure cannot be generated because the compression ratio is reduced regardless of the flow rate of the fluid.

In particular, the surge phenomenon can cause serious problems in the air compressor 200, and preparation for this is a very important consideration in the design of the system.

That is, if the operating point of the air compressor 200 deviates from the normal operating region (B) and falls within the surge region (C), the pressure and flow rate of the fluid fluctuate periodically, reducing the accuracy of control, and the fluctuations cause vibration and noise. This causes serious problems, such as damage to the air compressor 200 when operated for a long time.

Meanwhile, as previously seen, when a fuel cell vehicle drives on a flooded road, back pressure may be formed in the discharge passage. That is, in a flooded situation of the fuel cell system, back pressure is formed in the discharge passage, so the outlet pressure of the air compressor 200 increases and the flow rate of air sucked into the air compressor 200 decreases.

Accordingly, the operating point of the air compressor 200 moves toward the upper left direction on the graph of FIG. 3 (air flow rate decreases, outlet pressure increases), and if the degree of movement of the operating point is large, a surge occurs in the normal operation region (B). It can be moved to area (C).

That is, when flooding of the fuel cell system occurs, there is a risk that the air compressor 200 deviates from the normal operating range and operates in the surge region C.

Therefore, the recovery control method when the fuel cell system of a vehicle according to the present invention is flooded controls the rotation speed of the air compressor 200 to prevent or eliminate the operation of the air compressor 200 in the surge region C. carry out.

The operating principle of a general air compressor 200 is as follows. The air sucked into the air compressor 200 gains kinetic energy as it passes through the impeller, rapidly increasing its speed. High-speed air goes through a diffusion process in the diffuser, and as a result, the rapidly increased speed is reduced. In this process, the difference in kinetic energy due to the difference in speed is converted into pressure energy. And this is based on Bernoulli's equation.

That is, in light of the operating principle of the air compressor 200, when the rotation speed of the air compressor 200 increases, the flow rate of air sucked into the air compressor 200 increases and the outlet of the air compressor 200 increases. The pressure rises.

Therefore, when the rotational speed of the air compressor 200 increases, the operating point of the air compressor 200 moves toward the upper right on the graph of FIG. 3 (air flow rate increases, outlet pressure increases), and thus the air compressor 200 The operating point can return from the surge region to the normal operating region.

In addition, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention increases the rotation speed of the air compressor 200 when it is determined that the flooding situation of the fuel cell system has been resolved. Normal control is achieved.

As a result, there is an effect of directly resolving the flooding situation of the fuel cell system through control that increases the rotation speed of the air compressor 200.

For reference, the plurality of curves expressed horizontally in FIG. 3 schematically represent only a portion of the performance curve of the air compressor.

Meanwhile, the step (S100) of determining whether the fuel cell system is flooded in the flood recovery control method for the fuel cell system of a vehicle according to the present invention calculates the target flow rate of air supplied to the fuel cell stack based on the required output. step (S110), determining whether the outlet pressure of the air compressor is abnormal based on a preset reference value according to the calculated target flow rate of air (S120), and if there is an abnormality in the outlet pressure of the air compressor, the fuel cell system It may include determining that it is flooded (S130).

As previously discussed, when a flooding situation occurs in the fuel cell system, the outlet pressure of the air compressor 200 increases as back pressure is formed in the discharge passage.

Therefore, it is possible to detect a flooding situation in the fuel cell system by determining whether the outlet pressure of the air compressor 200 is abnormal.

The outlet pressure of the air compressor 200 is determined according to the flow rate of air sucked into the air compressor 200, and the flow rate of air sucked into the air compressor 200 is controlled to follow the target flow rate.

Here, the target flow rate refers to the minimum flow rate of air supplied to the fuel cell stack 100 based on the required output of the fuel cell vehicle user (driver), and the fuel cell demonstrates the corresponding output performance under specific required output conditions. It can be understood as the minimum air flow rate required to achieve this.

Specifically, the target flow rate is calculated by the following formula.

[Equation 1]

In Equation 1 above, 'SR' is the supercharging ratio of air and means the target flow rate compared to the actual flow rate of air, '3.6' is a coefficient for converting to the unit of flow rate (kg/h), and '4.0' is 1 mole ( mol) refers to the number of electrons transferred to oxygen. In addition, the molecular weight of air refers to the average molecular weight of air (28.84 g/mol), and the oxygen volume ratio in air is calculated as '21%'.

In other words, when a driver's request occurs, the fuel cell system determines the required output and required current of the fuel cell. Then, the target flow rate is calculated based on the required current (target current demand) according to the required output according to Equation 1 above, and then the fuel cell system is operated when the actual flow rate of air sucked into the air compressor 200 reaches the target flow rate. By continuously increasing the number of revolutions of the air compressor 200, the required output can be satisfied.

Meanwhile, referring to FIG. 3, depending on the size of the outlet pressure of the air compressor 200 at a specific air flow rate, the operating point of the air compressor 200 may correspond to the normal operation region (B) and the surge region (C). It can be seen that this may apply.

Therefore, even if the target flow rate determined according to the required output is the same, if the outlet pressure of the air compressor 200 increases above a certain pressure, the operating point of the air compressor 200 changes from the normal operation region (B) to the surge region (C). can be moved

That is, when the target flow rate is determined according to the required output, there is an outlet pressure allowable value at which the air compressor 200 can be operated within the normal operation region (B). And this outlet pressure allowable value can be understood to mean a point on the reference line that separates the normal operation area (B) and the surge area (C) in FIG. 3.

Therefore, in the step (S120) of determining whether the outlet pressure of the air compressor is abnormal based on a reference value prepared in advance according to the target flow rate of air calculated in the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention, 'Calculate The 'standard value prepared in advance according to the target flow rate of air' refers to the allowable value of the outlet pressure of the air compressor 200 at the target flow rate determined according to the required output.

That is, if the outlet pressure of the air compressor 200 becomes higher than the allowable value, it is determined that there is an abnormality in the outlet pressure of the air compressor 200 (the operating point of the air compressor 200 corresponds to the surge region C). do.

In this way, when there is an abnormality in the outlet pressure of the air compressor 200, it is assumed that back pressure is formed in the discharge passage, and accordingly, it is possible to detect a flooding situation in the fuel cell system.

As a result, it is possible to determine whether or not the fuel cell system is flooded by utilizing the configuration of the existing fuel cell system without adding a separate device, thereby overcoming the existing technical limitations and eliminating the problem of additional material cost increases. There is an advantage to preventing it.

Meanwhile, the step (S120) of determining whether the outlet pressure of the air compressor is abnormal based on a reference value prepared in advance according to the target flow rate of air calculated in the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention is the air pressure. Measuring the outlet pressure of the air compressor by the sensor (S121) and comparing the outlet pressure of the air compressor measured by the air pressure sensor with a preset reference value according to the target flow rate of air calculated based on the required output at the outlet of the air compressor. It may include a step (S122) of determining whether the pressure is abnormal.

Referring to FIG. 2, the fuel cell system may be equipped with an air pressure sensor 220 provided at the outlet of the air compressor 200 to measure the outlet pressure of the air compressor 200. In other words, the recovery control method when a vehicle's fuel cell system is flooded according to the present invention can measure the outlet pressure of the air compressor 200 in real time by utilizing the air pressure sensor 220.

And, the outlet pressure of the air compressor 200 measured by the air pressure sensor 220 is compared with a preset reference value according to the target flow rate of air calculated based on the required output to determine whether the outlet pressure of the air compressor 200 is abnormal. judge.

Here, the 'standard value prepared in advance according to the calculated target flow rate of air' refers to the allowable outlet pressure value of the air compressor 200 at the target flow rate determined according to the required output, as discussed above.

That is, if the outlet pressure of the air compressor 200 measured by the air pressure sensor 220 is higher than the allowable value, it is determined that there is an abnormality in the outlet pressure of the air compressor 200, and other specific operating principles are described above. Since it is the same as what was described above, it will be omitted.

Meanwhile, after the step (S110) of calculating the target flow rate of air supplied to the fuel cell stack based on the required output of the recovery control method when the vehicle's fuel cell system is flooded according to the present invention, the air flow rate sensor is transferred to the air compressor. A step of measuring the flow rate of incoming air (S111) and a step of determining whether the flow rate of supplied air is insufficient according to the difference between the air flow rate measured by the air flow sensor and the target air flow rate calculated based on the required output (S112) ) may further be included.

Referring to FIG. 2, the fuel cell system may be equipped with an air flow sensor 210 provided at the inlet of the air compressor 200 to measure the flow rate of air sucked into the air compressor 200. In other words, the recovery control method when a vehicle's fuel cell system is flooded according to the present invention can measure the flow rate of air sucked into the air compressor 200 in real time by utilizing the air flow sensor 210.

Meanwhile, as seen above, in a flooded situation of the fuel cell system, back pressure is formed in the discharge passage, which increases the outlet pressure of the air compressor 200 and reduces the flow rate of air sucked into the air compressor 200.

In other words, whether the fuel cell system is flooded can be determined through changes in the flow rate of air sucked into the air compressor 200, instead of using more than the outlet pressure of the air compressor 200.

In addition, the flow rate of air sucked into the air compressor 200 is measured through the air flow sensor 210 provided at the inlet of the air compressor 200, so the air pressure sensor 220 provided at the outlet of the air compressor 200 There is an advantage in that it is possible to determine whether the fuel cell system is flooded more quickly than the outlet pressure of the air compressor 200 measured through .

Therefore, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention determines whether the supply air flow rate is insufficient according to the difference between the air flow rate measured by the air flow sensor and the target air flow rate calculated based on the required output. A judgment step (S112) may be further included.

In Figure 1, the difference between the target air flow rate and the inlet air flow rate is expressed by comparing it with a separate reference value A. Here, the separate reference value A is a preset value based on the difference between the target air flow rate and the incoming air flow rate, and means the amount of change in flow rate over a certain period of time.

In other words, if the difference between the target air flow rate and the incoming air flow rate is less than the reference value A for a certain period of time, it means that the actual flow rate is significantly insufficient compared to the target flow rate (air flow rate insufficient state) continues for a certain period of time. It can be understood as doing so.

However, unlike whether the outlet pressure of the air compressor 200 is abnormal, the condition in which the air flow rate is insufficient may occur even when the fuel cell system is not flooded as follows.

In other words, there are cases where the fuel cell system is in a flooded situation and the air flow rate is insufficient depending on the back pressure formed in the discharge passage. However, even if the fuel cell system is not flooded, a problem occurs in the air supply system itself and the air flow rate is insufficient. The flow rate may be judged to be insufficient.

To distinguish this, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention determines whether the air flow rate is insufficient and then determines whether the outlet pressure of the air compressor 200 is abnormal.

Specifically, if there is an abnormality in the outlet pressure of the air compressor 200, it is determined that the fuel cell system is flooded.

On the other hand, if the outlet pressure of the air compressor 200 is normal, it is determined that the fuel cell system is not flooded, but a problem has occurred in the air supply system itself, and a warning signal can be notified to the driver.

Accordingly, it is possible to more precisely and accurately determine whether the fuel cell system is flooded, and it is also possible to detect when a problem occurs in the air supply system, which has the effect of increasing driver safety.

FIG. 1 is a flow chart of a recovery control method when a vehicle's fuel cell system is flooded according to an embodiment of the present invention, and FIG. 4 is a current limit ratio of the fuel cell stack 100 according to the difference between the measured flow rate of air and the target flow rate. This is a graph showing .

Referring to Figures 1 and 4, the step (S200) of performing recovery control of the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention involves increasing the rotation speed of the air compressor and simultaneously increasing the speed measured by the air flow sensor. The current of the fuel cell stack may be limited according to a preset reference value depending on the difference in the target flow rate of air supplied to the fuel cell stack based on the air flow rate and the required output (S210).

As previously seen through Equation 1 for calculating the target flow rate, when a driver's request occurs, the fuel cell system determines the required output and required current of the fuel cell, and sets the target flow rate based on the required current (target current demand) according to the requested output. Calculate .

In other words, when the required output according to the driver's request is excessively high, the target current demand also increases, so the target flow rate is also calculated at an excessively high value.

The rotation speed of the air compressor 200 increases until the actual flow rate of air sucked into the air compressor 200 reaches the target flow rate. Therefore, if the target flow rate is excessively high, the rotation speed of the air compressor 200 increases rapidly. can be increased.

If the rotation speed of the air compressor 200 suddenly increases, excessive vibration or shaking of the air compressor 200 may occur momentarily, and the fuel cell system may be flooded, causing the air compressor 200 to be in a surge area (C). ), there is a risk that the air compressor 200 may be damaged due to an instantaneous increase in vibration.

Therefore, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention limits the current of the fuel cell stack 100 and gradually increases the rotation speed of the air compressor 200, thereby increasing the rotation of the air compressor 200. It is intended to prevent problems such as damage to the air compressor 200 due to a rapid increase in number. In other words, this can be understood as maintaining the rotation speed increase rate of the air compressor 200 at an appropriate level.

Specifically, the step of performing the recovery control of the present invention (S200) increases the rotation speed of the air compressor 200 and simultaneously calculates the fuel flow rate based on the 'air flow rate measured by the air flow sensor 210' and 'required output. The current of the fuel cell stack 100 is limited according to a preset reference value according to the difference in the 'target flow rate' of air supplied to the battery stack 100.

The larger the difference between the actual flow rate of air and the target flow rate, the higher the rotational speed increase rate of the air compressor 200, so it is necessary to apply a higher rate for limiting the current of the fuel cell stack 100.

Therefore, the present invention is based on the difference between the 'air flow rate measured by the air flow sensor 210' and the 'target flow rate of air supplied to the fuel cell stack 100 based on the required output'. is to limit the current.

And the 'reference value prepared in advance according to the difference between the air flow rate measured by the air flow sensor 210 and the target flow rate of air supplied to the fuel cell stack 100 based on the required output' is explained with reference to FIG. 4. Do this.

In FIG. 4, the x-axis represents the difference between the target flow rate of air supplied to the fuel cell stack 100 based on the air flow rate measured by the air flow sensor 210 and the required output (difference between the measured air flow rate and the target flow rate). This means that the y-axis refers to the ratio (current limitation ratio) that limits the current of the fuel cell stack 100.

That is, as mentioned above, the larger the difference between the measured air flow rate and the target flow rate, the higher the current limit ratio is applied, so that the rotational speed increase rate of the air compressor 200 can be maintained at an appropriate level.

At this time, 'a reference value prepared in advance according to the difference between the target flow rate of air supplied to the fuel cell stack 100 based on the air flow rate measured by the air flow sensor 210 and the required output' is the measured air flow rate and the target air flow rate. The limiting current value is calculated based on the current limiting ratio determined according to the difference in flow rate.

For example, if the required current (target current demand) according to the required output is '300 A (Ampere, unit of current)' and the current limit ratio determined according to the difference between the measured air flow rate and the target flow rate is 20%, 'A reference value prepared in advance according to the difference between the target flow rate of air supplied to the fuel cell stack 100 based on the air flow rate measured by the air flow sensor 210 and the required output' is '240 A (Ampere, current of Unit)'.

If the difference between the measured air flow rate and the target flow rate is larger, and the current limit ratio determined accordingly is 30%, the fuel cell stack is 'based on the air flow rate measured by the air flow sensor 210 and the required output. The standard value prepared in advance according to the difference in the target flow rate of air supplied to (100) is calculated as '210 A (Ampere, unit of current)'.

As a result, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention controls the increase in rotation speed of the air compressor 200 and simultaneously limits the current of the fuel cell stack 100, thereby increasing the flow rate of the air compressor 200. By maintaining the rotational speed increase rate at an appropriate level, there is an effect of preventing problems such as damage to the air compressor 200 due to a rapid increase in the rotational speed of the air compressor 200.

For reference, if the difference between the measured flow rate of air and the target flow rate in FIG. 4 corresponds to the area to the left of point E, the current of the fuel cell stack 100 is not limited.

In other words, the current of the fuel cell stack 100 is limited only when the difference between the measured air flow rate and the target flow rate is greater than a certain flow rate.

This is because, when a fuel cell vehicle is actually driven, a difference between the measured air flow rate and the target flow rate naturally occurs. If the difference is only within a certain flow rate, the air compressor (air compressor) mentioned above even if the current of the fuel cell stack 100 is not limited. 200) This is because problems such as damage do not occur.

Continuing to refer to FIG. 1 , the step (S200) of performing recovery control of the recovery control method upon flooding of the fuel cell system of a vehicle according to the present invention involves increasing the rotation speed of the air compressor 200 and then increasing the number of rotations of the fuel cell stack 100. ) may be characterized by increasing the opening amount of the hydrogen supply valve 121 that supplies hydrogen to the anode 120 side (S220).

Referring to FIG. 2, the fuel cell system may be further equipped with a hydrogen supply valve 121 that supplies hydrogen to the anode 120 of the fuel cell stack 100.

When the fuel cell system is in a flooded state and back pressure is formed in the discharge passage, the outlet portions of each of the cathode 110 and the anode 120 communicate with the discharge passage through the shell side of the air humidifier 500, so the back pressure in the discharge passage is This may cause a problem of air flowing back toward the anode 120.

Therefore, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention is to increase the pressure on the anode 120 by controlling the increase in the opening amount of the hydrogen supply valve 121 after controlling the increase in the rotation speed of the air compressor 200. By raising it, it is intended to prevent the problem of air flowing back toward the anode 120.

At this time, the opening amount of the hydrogen supply valve 121 is preferably controlled so that the pressure on the anode 120 increases by an amount equal to the increase in the back pressure formed in the discharge passage. Here, measuring the increase in back pressure formed in the discharge passage has the problem of requiring an additional pressure sensor in the discharge passage, so the present invention utilizes the outlet pressure of the air compressor 200, which increases in proportion to the back pressure formed in the discharge passage.

That is, the increase in outlet pressure of the air compressor 200 is calculated, and the opening amount of the hydrogen supply valve 121 is controlled so that the pressure at the anode 120 increases according to the calculated value.

For reference, the increase in outlet pressure of the air compressor 200 is 'the outlet pressure of the air compressor 200 measured by the air pressure sensor 220' and 'the outlet of the air compressor 200 at the target flow rate determined according to the required output. It can be calculated through the difference in pressure tolerance.

Here, the 'air compressor (200) outlet pressure allowable value at the target flow rate determined according to the required output' is a pre-arranged value according to the target flow rate of air calculated based on the required output and the outlet pressure of the air compressor measured by the air pressure sensor. Referred to in the step (S122) of determining whether the outlet pressure of the air compressor is abnormal by comparing it with the reference value, it means 'a reference value prepared in advance according to the calculated target flow rate of air.'

As a result, the step (S200) of performing recovery control of the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention involves supplying hydrogen to the anode 120 of the fuel cell stack 100 as described above. By increasing the pressure on the anode 120 side by controlling the increase in the opening amount of the valve 121, the problem of air flowing back toward the anode 120 can be prevented, thereby improving the durability and safety of the fuel cell system.

Meanwhile, the step (S200) of performing recovery control of the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention involves increasing the rotation speed of the air compressor and then transferring the air that has passed through the cathode of the fuel cell stack to the outside of the vehicle. It may be characterized by increasing the opening amount of the air discharge valve (S230).

Referring to FIG. 2, the fuel cell system may be further equipped with an air discharge valve 112 that discharges air that has passed through the cathode 110 of the fuel cell stack 100 to the outside of the vehicle. Due to the nature of discharging air that has passed through the cathode 110 to the outside of the vehicle, the air discharge valve 112 is preferably provided adjacent to the exhaust port on the discharge passage.

When the fuel cell system is in a flooded state and back pressure is formed in the discharge passage, as the opening amount of the air discharge valve 112 is increased, the level of water flowing into the discharge passage is lowered, thereby reducing the back pressure.

Accordingly, the outlet pressure of the air compressor 200, which is increased due to the rotation speed increase control of the air compressor 200, forms a higher pressure than the reduced back pressure as above, thereby increasing the efficiency of the rotation speed increase control of the air compressor 200. There is an advantage.

Meanwhile, after the step of performing recovery control of the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention (S200), a step of determining whether the flooding situation of the fuel cell system is resolved based on the outlet pressure of the air compressor. (S240) and, if the flooding situation is not resolved, a step of gradually increasing the opening amount of the air discharge valve (S250) may be further included.

Specifically, the step (S240) of determining whether the flooding situation of the fuel cell system has been resolved based on the outlet pressure of the air compressor is based on the required output based on the outlet pressure of the air compressor 200 measured by the air pressure sensor 220. The calculated target air flow rate is compared with a preset reference value, and it is determined whether the outlet pressure abnormality of the air compressor 200 has been resolved.

This is a decision that is contrary to the step (S122) of determining whether the outlet pressure of the air compressor is abnormal by comparing the outlet pressure of the air compressor measured by the air pressure sensor with a preset reference value according to the target flow rate of air calculated based on the required output. It can be understood as carrying out.

That is, if the outlet pressure of the air compressor 200 is greater than the reference value (allowable outlet pressure of the air compressor 200 at the target flow rate determined according to the required output), it is determined that there is an abnormality in the outlet pressure of the air compressor 200. Conversely, if the outlet pressure of the air compressor 200 is less than the reference value (allowable outlet pressure of the air compressor 200 at the target flow rate determined according to the required output), the outlet pressure of the air compressor 200 is abnormal. It is judged that the flooding situation of the fuel cell system has been resolved.

Continuing, if the flooding situation is not resolved, a step (S250) of gradually increasing the opening amount of the air discharge valve is performed.

As discussed above, by increasing the opening amount of the air discharge valve 112, this has the effect of reducing the back pressure formed in the discharge passage and increasing the efficiency of controlling the increase in rotation speed of the air compressor 200.

However, in this step, by additionally increasing the opening amount of the air discharge valve 112, the back pressure formed in the discharge passage can be further reduced and the efficiency of controlling the increase in rotation speed of the air compressor 200 can be further improved. Accordingly, the flooding situation of the fuel cell system can be quickly resolved.

For reference, if the opening amount of the air discharge valve 112 is suddenly increased, additional problems such as difficulty in precise control may occur, so in this step, the opening amount is increased gradually or step by step (for example, 5 seconds every 5 seconds). This problem is also attempted to be prevented by increasing the opening amount of the air discharge valve 112 by degrees.

Meanwhile, in the step (S250) of gradually increasing the opening amount of the air discharge valve in the flood recovery control method of the fuel cell system of a vehicle according to the present invention, when the opening amount of the air discharge valve is fully opened, the fuel cell system It may be characterized by stopping the operation (S252).

When the opening amount of the air discharge valve 112 is fully opened, the opening amount cannot be increased any further, so if the fuel cell vehicle continues to drive on a flooded road, the flooding situation of the fuel cell system may not be resolved.

In addition, as the flooding situation continues, if the entire cross-section of the outlet is completely blocked, water may flow into the fuel cell system along the discharge channel, causing failure of the fuel cell system itself.

Therefore, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention gradually increases the opening amount of the air discharge valve 112, and when the air discharge valve 112 reaches the point where it is fully opened, recovery control is no longer performed. There is an advantage in preventing the problem from progressing to a complete flooding situation in advance by determining that the situation cannot be carried out and stopping the operation of the fuel cell system.

Meanwhile, in the step (S250) of gradually increasing the opening amount of the air discharge valve in the flood recovery control method of the fuel cell system of a vehicle according to the present invention, when the opening amount of the air discharge valve 112 is fully opened, the air discharge valve 112 is fully opened. The operation of the fuel cell system may be stopped after closing the air supply valve 111 that supplies the air passing through the compressor 200 to the cathode 110 of the fuel cell stack 100 (S251). .

Referring to FIG. 2, the fuel cell system may be further equipped with an air supply valve 111 that supplies air that has passed through the air compressor 200 to the cathode 110 of the fuel cell stack 100. The air supply valve 111 has a plurality of passages formed inside, one passage supplying air to the cathode 110 and the other passage introducing air discharged from the cathode 110.

That is, it is formed so that the flow rate of air inside the cathode 110 can be adjusted by closing or opening one air supply valve 111.

Therefore, if it is determined that the air discharge valve 112 is completely open and recovery control can no longer be performed, the air supply valve 111 is closed before stopping the operation of the fuel cell system to prevent water from being completely flooded. We want to make sure to block the inflow.

Accordingly, there is an effect of more reliably preventing failure of the fuel cell system due to water inflow in a complete submersion situation.

Figure 2 is a diagram showing a recovery control system when a fuel cell system of a vehicle is flooded according to an embodiment of the present invention.

Referring to FIG. 2, the recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention includes a fuel cell stack 100 including a cathode 110 to which air is supplied and an anode 120 to which hydrogen is supplied. Determine whether the air compressor 200 that supplies air to the cathode 110 of the fuel cell stack 100 and the fuel cell system of the vehicle are flooded, and if it is determined that the fuel cell system is flooded, the fuel cell stack 100 ), recovery control is performed by controlling the air compressor 200 to increase the rotation speed of the air compressor 200, which supplies air to the cathode 110 side, and flooding of the fuel cell system is prevented after increasing the rotation speed of the air compressor 200. It includes a controller 300 that normally controls the rotation speed of the air compressor 200 when it is determined that the situation has been resolved.

Controller 300 according to an exemplary embodiment of the present invention includes a non-volatile memory (not shown) configured to store data regarding algorithms configured to control the operation of various components of a vehicle or software instructions for reproducing the algorithms. It may be implemented through a processor (not shown) configured to perform the operations described below using data stored in memory. Here, the memory and processor may be implemented as individual chips. Alternatively, the memory and processor may be implemented as a single chip integrated with each other, and the processor may take the form of one or more processors.

The controller 300 determines whether the fuel cell system is flooded by using the change in the outlet pressure of the air compressor 200 due to the increase in back pressure under flooded conditions. Since the specific operating principle for this is the same as described above, it will be omitted.

In a flooded situation of the fuel cell system, back pressure is formed in the discharge passage, so the outlet pressure of the air compressor 200 increases and the flow rate of air sucked into the air compressor 200 decreases.

Accordingly, the operating point of the air compressor 200 moves toward the upper left direction on the graph of FIG. 3 (air flow rate decreases, outlet pressure increases), and the air compressor 200 deviates from the normal operating range and falls in the surge region C. Driving is dangerous.

Therefore, when it is determined that the fuel cell system is flooded, the controller 300 operates the air compressor 200 to increase the rotation speed of the air compressor 200 that supplies air to the cathode 110 of the fuel cell stack 100. Control and perform recovery control.

Here, the recovery control is performed by limiting the current of the fuel cell stack 100 while increasing the rotation speed of the air compressor 200, or by increasing the rotation speed of the air compressor 200 and then using the hydrogen supply valve 121 or the air discharge valve ( 112) refers to a control that increases the opening amount, and the specific operating principle for this is the same as described above, so it is omitted.

When the rotational speed of the air compressor 200 increases, the flow rate of air sucked into the air compressor 200 increases and the outlet pressure of the air compressor 200 increases.

Therefore, when the rotational speed of the air compressor 200 increases, the operating point of the air compressor 200 moves toward the upper right on the graph of FIG. 3 (air flow rate increases, outlet pressure increases), and thus the air compressor 200 The operating point returns from the surge region (C) to the normal operation region (B).

Additionally, the controller 300 normally controls the rotation speed of the air compressor 200 when it is determined that the flooding situation of the fuel cell system has been resolved after increasing the rotation speed of the air compressor 200.

For reference, when recovery control is performed to increase the opening amount of the air discharge valve 112, when the controller 300 normally controls the rotation speed of the air compressor 200, the increased air discharge valve 112 The rotation speed of the air compressor 200 can be normally controlled by reflecting the opening amount.

That is, if it is determined that the flooding situation of the fuel cell system has been resolved after increasing the opening amount of the air discharge valve 112, the opening amount of the air discharge valve 112 is also adjusted to a level corresponding to the normal operation region (B). must be reduced to the level

At this time, if the opening amount of the air discharge valve 112 is suddenly reduced, additional problems such as difficulty in precise control may occur, so the controller 300 gradually reduces the opening amount of the air discharge valve 112 (e.g. , the opening amount of the air discharge valve 112 can be reduced by 5 degrees every 5 seconds.

And the controller 300 can normally control the rotation speed of the air compressor 200 by reflecting the change in outlet pressure of the air compressor 200 according to the change in the opening amount of the air discharge valve 112.

Meanwhile, the recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention includes an air flow sensor 210 provided at the inlet of the air compressor 200 to measure the flow rate of air flowing into the air compressor 200. Further, the controller 300 calculates the target flow rate of air supplied to the fuel cell stack 100 based on the required output, and calculates the target flow rate of air measured by the air flow sensor 210 and the required output. Depending on the difference in the target flow rate of the supplied air, it is possible to determine whether the flow rate of the supplied air is insufficient.

The air flow sensor 210 is provided at the inlet of the air compressor 200 to measure the flow rate of air sucked into the air compressor 200.

The controller 300 calculates the target flow rate of air supplied to the fuel cell stack 100 based on the required output. Here, the target flow rate refers to the minimum flow rate of air supplied to the fuel cell stack 100 based on the required output of the fuel cell vehicle user (driver), and the fuel cell demonstrates the corresponding output performance under specific required output conditions. It can be understood as the minimum air flow rate required to achieve this.

That is, when a driver's request occurs, the fuel cell system controller 300 determines the required output and required current of the fuel cell, and the target flow rate is determined according to the required output.

Additionally, the controller 300 determines whether the flow rate of supplied air is insufficient based on the difference between the air flow rate measured by the air flow sensor 210 and the target air flow rate calculated based on the required output.

Here, the specific operating principle for determining whether the flow rate of supplied air is insufficient is the same as described above, so its description will be omitted.

On the other hand, in cases where the air flow rate is insufficient, as discussed above, the fuel cell system may be in a flooded situation and the air flow rate may be insufficient depending on the back pressure formed in the discharge passage. However, even if the fuel cell system is not flooded, the air flow rate may be insufficient. A problem may occur in the supply system itself and the air flow rate may be judged to be insufficient.

To distinguish this, the recovery control method in case of flooding of the fuel cell system of a vehicle according to the present invention determines whether the air flow rate is insufficient and then determines whether the outlet pressure of the air compressor 200 is abnormal.

Meanwhile, the recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention further includes an air pressure sensor 220 provided at the outlet of the air compressor 200 to measure the outlet pressure of the air compressor 200, , the controller 300 calculates the target flow rate of air supplied to the fuel cell stack 100 based on the required output, and calculates the outlet pressure of the air compressor 200 measured by the air pressure sensor 220 based on the required output. It is possible to determine whether the outlet pressure of the air compressor 200 is abnormal by comparing it with a preset reference value according to the calculated target flow rate of air.

The air pressure sensor 220 is provided at the outlet of the air compressor 200 to measure the outlet pressure of the air compressor 200. This air pressure sensor 220 measures the outlet pressure of the air compressor 200 in real time and transmits the measured pressure information to the controller 300.

And the controller 300 compares the outlet pressure of the air compressor 200 measured by the air pressure sensor 220 with a preset reference value according to the target flow rate of air calculated based on the required output to determine the outlet pressure of the air compressor 200. Determine whether the outlet pressure is abnormal.

Here, the 'standard value prepared in advance according to the calculated target flow rate of air' refers to the allowable outlet pressure value of the air compressor 200 at the target flow rate determined according to the required output, as discussed above.

That is, if the outlet pressure of the air compressor 200 measured by the air pressure sensor 220 is higher than the allowable value, it is determined that there is an abnormality in the outlet pressure of the air compressor 200, and other specific operating principles are described above. Since it is the same as what was described above, it is omitted.

Meanwhile, the recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention includes a hydrogen supply valve 121 that supplies hydrogen to the anode 120 of the fuel cell stack 100 and a cathode of the fuel cell stack 100. It further includes an air discharge valve 112 that discharges the air passing through (110) to the outside of the vehicle, and the controller 300 increases the rotation speed of the air compressor 200 and operates the hydrogen supply valve 121 and the air discharge valve. It may be characterized by controlling the hydrogen supply valve 121 and the air discharge valve 112 so that the opening amount of (112) is increased.

The controller 300 increases the pressure on the anode 120 by controlling the increase in the opening amount of the hydrogen supply valve 121, so that when the fuel cell system is in a flooded state and back pressure is formed in the discharge passage, the anode ( 120) Prevents the problem of air flowing back to the side.

Here, the specific increase in the opening amount of the hydrogen supply valve 121 and the control principle are the same as described above, so description thereof will be omitted.

Since the air discharge valve 112 discharges air that has passed through the cathode 110 to the outside of the vehicle, the air discharge valve 112 is preferably provided adjacent to the exhaust port on the discharge passage.

The controller 300 has the advantage of increasing the efficiency of controlling the increase in rotation speed of the air compressor 200 by reducing the back pressure by lowering the water level of the water flowing into the discharge passage through control of increasing the opening amount of the air discharge valve 112. there is.

Meanwhile, the recovery control system in case of flooding of the fuel cell system of a vehicle according to the present invention includes an air supply valve 111 that supplies air that has passed through the air compressor 200 to the cathode 110 of the fuel cell stack 100. Additionally, the controller 300 may be configured to stop the operation of the fuel cell system after closing the air supply valve 111 when the opening amount of the air discharge valve 112 is fully opened.

As seen above, when the opening amount of the air discharge valve 112 is fully opened, the opening amount cannot be increased any further, so the flooding situation in the fuel cell system may not be resolved, and in the case where the cross section of the outlet is completely blocked, In the case of a complete flooding situation, water may flow into the interior along the discharge channel, causing failure of the fuel cell system itself.

Therefore, when the air discharge valve 112 is fully opened, the controller 300 determines that recovery control can no longer be performed and stops the operation of the fuel cell system to prevent the problem from progressing to a complete flooding situation. We want to prevent this.

Meanwhile, one flow path for supplying air to the cathode 110 and another flow path for introducing air discharged from the cathode 110 are formed inside the air supply valve 111. That is, it is formed so that the flow rate of air inside the cathode 110 can be adjusted by closing or opening one air supply valve 111.

Therefore, when the controller 300 determines that the air discharge valve 112 is completely open and recovery control can no longer be performed, the controller 300 closes the air supply valve 111 before stopping the operation of the fuel cell system. Ensure that water inflow is reliably blocked in a fully submerged situation.

Therefore, as described above, according to the recovery control method and system when the fuel cell system of a vehicle is flooded according to the present invention, whether or not it is flooded is determined from the relationship between the increase in back pressure in the flooded condition of the fuel cell system and the change in pressure at the outlet of the air compressor 200. By determining whether or not the fuel cell system is flooded, it is possible to determine whether or not it is flooded based on the configuration of the existing fuel cell system without installing a separate additional device to determine whether the fuel cell system will be flooded. This overcomes conventional technical limitations and eliminates the problem of additional material cost increases. It can be prevented.

In addition, by increasing the number of revolutions of the air compressor 200 and performing additional recovery control to relieve back pressure, damage to the air compressor 200 is prevented while eliminating flooding of the fuel cell system, and water inflow in a complete flooding situation. It has the advantage of being able to prevent fuel cell system failures in advance.

Although the invention has been shown and described in relation to specific embodiments, it is commonly known in the art that the present invention can be modified and changed in various ways without departing from the technical spirit of the invention as provided by the following claims. It will be self-evident to those with knowledge.

100: Fuel cell stack
110: cathode
111: air supply valve
112: air discharge valve
120: anode
121: Hydrogen supply valve
122: Hydrogen discharge valve
200: Air compressor
210: air flow sensor
220: Air pressure sensor
300: controller
400: Hydrogen tank
500: Air humidifier

Claims (15)

Determining whether the fuel cell system of the vehicle is flooded;
If it is determined that the fuel cell system is flooded, performing recovery control by controlling the air compressor to increase the rotation speed of the air compressor that supplies air to the cathode side of the fuel cell stack; and
A recovery control method in case of flooding of a fuel cell system of a vehicle, comprising: normalizing the rotation speed of the air compressor when it is determined that the flooding situation of the fuel cell system has been resolved after increasing the rotation speed of the air compressor.
In claim 1,
The steps to determine whether the fuel cell system is flooded are:
calculating a target flow rate of air supplied to the fuel cell stack based on the required output;
Determining whether the outlet pressure of the air compressor is abnormal based on a preset reference value according to the calculated target flow rate of air; and
A recovery control method when a fuel cell system of a vehicle is flooded, comprising: determining that the fuel cell system has been flooded when there is an abnormality in the outlet pressure of the air compressor.
In claim 2,
The step of determining whether the outlet pressure of the air compressor is abnormal based on a standard value prepared in advance according to the calculated target flow rate of air is:
Measuring the outlet pressure of the air compressor using an air pressure sensor; and
Comparing the outlet pressure of the air compressor measured by the air pressure sensor with a preset reference value according to the target flow rate of air calculated based on the required output to determine whether the outlet pressure of the air compressor is abnormal. Recovery control method when a vehicle's fuel cell system is flooded.
In claim 2,
After calculating the target flow rate of air supplied to the fuel cell stack based on the required output,
Measuring the flow rate of air flowing into the air compressor from the air flow sensor; and
A step of determining whether the flow rate of supplied air is insufficient according to the difference between the air flow rate measured by the air flow sensor and the target air flow rate calculated based on the required output. Recovery control method in case of flooding.
In claim 4,
The steps to perform recovery control are:
At the same time as the rotation speed of the air compressor increases, the current of the fuel cell stack is limited according to a preset standard value according to the difference between the target flow rate of air supplied to the fuel cell stack based on the air flow rate measured by the air flow sensor and the required output. A recovery control method in case of flooding of a fuel cell system of a vehicle, characterized in that.
In claim 1,
The steps to perform recovery control are:
A recovery control method in case of flooding of a fuel cell system of a vehicle, characterized in that the opening amount of the hydrogen supply valve that supplies hydrogen to the anode side of the fuel cell stack is increased after increasing the rotation speed of the air compressor.
In claim 1,
The steps to perform recovery control are:
A recovery control method in case of flooding of a fuel cell system of a vehicle, characterized in that after increasing the rotation speed of the air compressor, the opening amount of the air discharge valve that discharges the air that has passed through the cathode of the fuel cell stack to the outside of the vehicle is increased.
In claim 1,
After the recovery control stage,
Determining whether the flooding situation of the fuel cell system has been resolved based on the outlet pressure of the air compressor; and
A recovery control method in case of flooding of a fuel cell system of a vehicle, further comprising: gradually increasing the opening amount of the air discharge valve when the flooding situation is not resolved.
In claim 8,
The step of gradually increasing the opening amount of the air discharge valve is:
A recovery control method in case of flooding of a fuel cell system of a vehicle, characterized in that the operation of the fuel cell system is stopped when the opening amount of the air discharge valve is fully opened.
In claim 8,
The step of gradually increasing the opening amount of the air discharge valve is:
A fuel cell system for a vehicle characterized in that when the opening amount of the air discharge valve is fully opened, the air supply valve that supplies the air that passed through the air compressor to the cathode of the fuel cell stack is closed and the operation of the fuel cell system is stopped. Recovery control method in case of flooding.
A fuel cell stack including a cathode supplied with air and an anode supplied with hydrogen;
An air compressor that supplies air to the cathode side of the fuel cell stack; and
Determines whether the vehicle's fuel cell system has been flooded, and if it is determined that the fuel cell system has been flooded, recovery control is performed by controlling the air compressor to increase the rotation speed of the air compressor that supplies air to the cathode side of the fuel cell stack. , a controller that normally controls the rotation speed of the air compressor when it is determined that the flooding situation of the fuel cell system has been resolved after increasing the rotation speed of the air compressor.
In claim 11,
It further includes an air flow sensor provided at the inlet of the air compressor to measure the flow rate of air flowing into the air compressor,
The controller calculates the target flow rate of air supplied to the fuel cell stack based on the required output, and the supply air flow rate is insufficient according to the difference between the air flow rate measured by the air flow sensor and the target air flow rate calculated based on the required output. A recovery control system in case of flooding of a vehicle's fuel cell system, characterized in that it determines whether or not the vehicle's fuel cell system is flooded.
In claim 11,
It further includes an air pressure sensor provided at the outlet of the air compressor to measure the outlet pressure of the air compressor,
The controller calculates the target flow rate of air supplied to the fuel cell stack based on the required output, and matches the outlet pressure of the air compressor measured by the air pressure sensor to a preset reference value according to the target flow rate of air calculated based on the required output. A recovery control system in case of flooding of a vehicle's fuel cell system, characterized by comparing and determining whether the outlet pressure of the air compressor is abnormal.
In claim 11,
A hydrogen supply valve that supplies hydrogen to the anode side of the fuel cell stack; and
It further includes an air discharge valve that discharges air that has passed through the cathode of the fuel cell stack to the outside of the vehicle,
A recovery control system in case of flooding of a vehicle's fuel cell system, characterized in that the controller controls the hydrogen supply valve and the air discharge valve to increase the opening amount of the hydrogen supply valve and the air discharge valve after increasing the rotation speed of the air compressor.
In claim 14,
It further includes an air supply valve that supplies air that has passed through the air compressor to the cathode of the fuel cell stack,
A recovery control system in case of flooding of the fuel cell system of a vehicle, characterized in that the controller stops the operation of the fuel cell system after closing the air supply valve when the opening amount of the air discharge valve is fully opened.

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