KR102439629B1 - Control method and control system for fuel cell vehicle - Google Patents

Abstract

learning the driving tendency of the driver; determining whether an idle stop of the fuel cell is possible based on the learned driving tendency; and stopping the fuel cell when it is determined that the idle stop is possible, and when the entry condition for the idle stop is satisfied.

Description

Control method and control system for fuel cell vehicle

The present invention relates to a control method and a control system for a fuel cell vehicle, and more particularly, to a technology for controlling whether an idle stop of a fuel cell stack is possible based on a driving tendency and a deterioration state.

A fuel cell converts chemical energy into electrical energy using redox reactions of hydrogen and oxygen supplied from a hydrogen supply device and an air supply device, respectively. A fuel cell stack that produces electrical energy and a cooling system for cooling the same contains

That is, hydrogen is supplied to the anode side of the fuel cell stack, and an oxidation reaction of hydrogen proceeds at the anode to generate hydrogen ions (Protons) and electrons (Electrons). At this time, the generated hydrogen ions and electrons are separated from the electrolyte membrane, respectively It travels through the plate to the cathode. At the cathode, water is generated through an electrochemical reaction in which hydrogen ions and electrons moved from the anode and oxygen in the air participate, and electric energy is generated from the flow of these electrons.

In such a fuel cell system, the surplus power is charged when power output from the fuel cell remains, including a high-voltage battery or supercap that can be generally charged and discharged, and when the power is insufficient, the high-voltage battery or supercap is discharged to use supplementary power. .

Accordingly, a technology has been developed to improve the power generation efficiency of the fuel cell and increase the fuel efficiency accordingly through the fuel cell idle stop control, which stops the power generation of the fuel cell during the low-output section of the fuel cell or during regenerative braking. .

However, fuel cell buses that frequently start/stop among fuel cell vehicles using fuel cells as a driving source adversely affect initial responsiveness when the idle stop is released, so the fuel cell idle stop control is generally not used. .

That is, the fuel cell bus does not use the fuel cell idle stop control because there is a high possibility that drivability is adversely affected when the idle stop control is used due to frequent start/stop, and thus the power generation efficiency of the fuel cell is deteriorated.

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

KR 10-1000703 B US 6484075 B

The present invention has been proposed to solve this problem, and an object of the present invention is to provide a method of controlling whether to activate the idle stop function by learning the driving tendency and deterioration state of the driver.

According to an aspect of the present invention, there is provided a control method for a fuel cell vehicle comprising: learning a driving tendency of a driver; determining whether an idle stop of the fuel cell is possible based on the learned driving tendency; and when it is determined that the idle stop is possible, stopping the fuel cell when the entry condition for the idle stop is satisfied.

In the learning step, the driver's driving tendency may be learned based on the output current of the fuel cell for a preset reference time.

In the learning step, the driver's driving propensity index can be calculated based on the current utilization rate indicating the degree of use for each size of the fuel cell output current or the current sudden increase rate indicating the degree of the rapid increase of the output current for each size of the fuel cell output current. .

The current utilization rate may be a ratio of a time of driving with the current for a preset reference time.

The current rapid increase rate is a ratio of the number of times that the current rapidly rises in the current range among the number of rapid increases that occurred during the preset reference time, and the rapid increase determination may be determined as a sudden increase if the current change rate per hour is greater than or equal to the preset change rate.

In the learning stage, the driving propensity index of the driver can be calculated by the following equation.

: 전류 이용률,

: 전류별 가중치,

: 전류 급상승률K : Driving propensity index, m : Number of ranges by size of current, I = Current,

: current utilization,

: weight by current,

: Current surge rate

In the step of determining whether the idle stop is possible, if the driving tendency index of the driver calculated based on the driving tendency of the driver learned in the learning step is equal to or greater than a preset first index, it may be determined that the idle stop is impossible.

In the step of determining whether an idle stop is possible, it is determined that a part of the fuel cell stack is capable of an idle stop if the driver's driving tendency index calculated based on the driver's driving tendency learned in the learning step is equal to or greater than a preset second index. can

After determining whether an idle stop is possible, determining a deterioration state of the fuel cell stack; further comprising, wherein the stopping of the fuel cell may include, when an idle stop entry condition is satisfied, A portion of the fuel cell stack having a relatively small degree of degradation calculated based on the degradation state may be stopped.

The step of determining the deterioration state of the fuel cell stack is based on the current utilization rate indicating the degree of use for each size of the fuel cell output current, and the continuous current utilization rate indicating the degree of continuous use for each size of the fuel cell output current. The deterioration state can be determined.

The current continuous use rate may be a ratio of the maximum continuous use time of the corresponding current among the continuous use times generated during the preset reference time.

It is possible to vary the reflection ratio of the current utilization rate and the current continuous utilization rate for each magnitude of the fuel cell output current.

In the step of determining the deterioration state of the fuel cell stack, the degree of deterioration of the fuel cell stack may be calculated using the following equation.

: 전류 이용률,

: 전류 연속이용률, α: 전류 이용률 반영률, β: 전류 연속이용률 반영률,

: Dry-Out 인자C : Degradation degree, m : Number of ranges by size of current, I = Current,

: current utilization,

: Current continuous utilization rate, α: Current utilization rate reflection rate, β: Current continuous use rate reflection rate,

: Dry-Out factor

According to an aspect of the present invention, there is provided a control system for a fuel cell vehicle comprising: a driving tendency determining unit configured to learn a driving tendency of a driver; and an idle stop determination unit that determines whether an idle stop of the fuel cell is possible based on the learned driving propensity, and stops the fuel cell if the idle stop entry condition is satisfied when it is determined that the idle stop is possible; may include

The method further includes a deterioration state determination unit determining a deterioration state of the fuel cell stack, wherein the idle stop determination unit determines a degree of deterioration calculated based on the determined deterioration state of the fuel cell stack when the entry condition of the idle stop is satisfied. It can stop part of a small fuel cell stack.

According to the control method and control system for a fuel cell vehicle of the present invention, it is possible to solve the problem of initial responsiveness when the idle stop is released by learning and reflecting the driving tendency.

In addition, when starting/stop of the fuel cell vehicle is not frequent according to driving tendency, fuel efficiency is improved by using the idle stop function.

In addition, it has the effect of improving the durability of the fuel cell stack by controlling the idle stop function by reflecting the deterioration state of the fuel cell stack.

1 is a flowchart of a method for controlling a fuel cell vehicle according to an embodiment of the present invention.
2 is a diagram illustrating a current utilization rate for each current magnitude according to an embodiment of the present invention.
3 is a diagram illustrating a current surge rate for each current magnitude according to an embodiment of the present invention.
4 is a view illustrating a reflection ratio of a current utilization rate and a continuous current utilization rate for each current magnitude according to an embodiment of the present invention.
5 is a block diagram of a control system for a fuel cell vehicle according to an embodiment of the present invention.

Specific structural or functional descriptions of the embodiments of the present invention disclosed in this specification or application are only exemplified for the purpose of describing the embodiments according to the present invention, and the embodiments according to the present invention may be implemented in various forms. and should not be construed as being limited to the embodiments described in the present specification or application.

Since the embodiment according to the present invention can have various changes and can have various forms, specific embodiments are illustrated in the drawings and described in detail in the present specification or application. However, this is not intended to limit the embodiment according to the concept of the present invention with respect to a specific disclosed form, and should be understood to include all changes, equivalents or substitutes included in the spirit and scope of the present invention.

Terms such as first and/or second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one element from another element, for example, without departing from the scope of the present invention, a first element may be called a second element, and similarly The second component may also be referred to as the first component.

When a component is referred to as being “connected” or “connected” to another component, it may be directly connected or connected to the other component, but it is understood that other components may exist in between. it should be On the other hand, when it is said that a certain element is "directly connected" or "directly connected" to another element, it should be understood that the other element does not exist in the middle. Other expressions describing the relationship between elements, such as "between" and "immediately between" or "neighboring to" and "directly adjacent to", etc., should be interpreted similarly.

The terms used herein are used only to describe specific embodiments, and are not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present specification, terms such as “comprise” or “have” are intended to designate that the described feature, number, step, operation, component, part, or combination thereof exists, and includes one or more other features or numbers. , it should be understood that it does not preclude the existence or addition of steps, operations, components, parts, or combinations thereof.

Unless defined otherwise, all terms used herein, including technical and scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Terms such as those defined in commonly used dictionaries should be interpreted as meanings consistent with the context of the related art, and unless explicitly defined in the present specification, they are not to be interpreted in an ideal or excessively formal meaning. .

Hereinafter, the present invention will be described in detail by describing preferred embodiments of the present invention with reference to the accompanying drawings. Like reference numerals in each figure indicate like elements.

1 is a flowchart of a method for controlling a fuel cell vehicle according to an embodiment of the present invention.

Referring to FIG. 1 , a method for controlling a fuel cell vehicle according to an embodiment of the present invention includes the steps of: learning a driving tendency of a driver ( S300 ); determining whether an idle stop of the fuel cell is possible based on the learned driving propensity (S410, S420); and when it is determined that the idle stop is possible, stopping the fuel cell when the condition for entering the idle stop is satisfied ( S710 , S720 , S730 , S740 ).

The step of learning the driver's driving tendency ( S300 ) is learning the driver's tendency to drive the vehicle for a preset reference time (driving cycle). When the vehicle is turned on (S100), when the vehicle is stopped and then restarted, data such as the operation amount (Depth) of the accelerator or the motoring current demand or the fuel cell current demand can be collected ( S200). A driving tendency may be determined according to the collected data (S300). Here, the driving tendency may mean how often the vehicle stops and restarts, or whether a rapid current is required when the vehicle starts again.

For example, in the step of learning ( S300 ) according to an embodiment, the driving tendency of the driver may be learned based on the output current of the fuel cell for a preset reference time. Here, the output current means the magnitude of the current output from the fuel cell stack, and it is possible to divide the current into m ranges according to the magnitude of the current, and calculate each factor for each range according to the magnitude of the current.

) 또는 연료전지 출력전류의 크기별로 출력전류가 급상승하는 정도를 나타내는 전류 급상승률(

)을 산출하고, 이들을 기반으로 운전자의 운전 성향 지수(K)를 산출할 수 있다.Specifically, the learning step ( S300 ) includes the current utilization rate (

) or the current rapid increase rate (

), and the driver's driving propensity index (K) can be calculated based on them.

2 is a diagram illustrating current utilization by current magnitude according to an embodiment of the present invention.

)은 기설정된 기준시간 동안 해당 전류로 운전된 시간의 비율일 수 있다. 즉, 전류 이용률(

)은 해당 전류의 범위 내에서 운전된 시간을 총 운전 시간으로 제산한 값으로 산출할 수 있다.Referring to Figure 2, the current utilization rate (

) may be a ratio of a time of operation with the current for a preset reference time. That is, the current utilization (

) can be calculated by dividing the operating time within the range of the current by the total operating time.

3 is a diagram illustrating a current surge rate for each current magnitude according to an embodiment of the present invention.

)은 기설정된 기준시간 동안 발생한 급상승 횟수 중 해당 전류 범위에서 급상승한 횟수의 비율일 수 있다. 즉, 전류 급상승률(

)은 해당 전류의 범위에서 급상승한 횟수를 총 발생한 급상승 횟수로 제산한 값으로 산출할 수 있다.Referring to FIG. 3 , the current surge rate (

) may be a ratio of the number of times of rapid increase in the current range among the number of times of rapid increase during the preset reference time. That is, the rate of current surge (

) can be calculated by dividing the number of sharp rises in the current range by the total number of sudden rises.

The rapid rise may be determined as a sudden rise if the rate of change of current per hour is equal to or greater than the preset rate of change (S). That is, if the rate of change of the current according to time change is equal to or greater than the preset rate of change (S) as shown below, it can be determined that the current has risen sharply.

The driver's driving propensity index (K) can be calculated by the following equation.

: 전류 이용률,

: 전류별 가중치,

: 전류 급상승률K : Driving propensity index, m : Number of ranges by size of current, I = Current,

: current utilization,

: weight by current,

: Current surge rate

)는 해당 전류로 운전된 횟수를 카운팅하여 이에 따라 설정할 수 있다. 즉, 해당 전류로 운전되는 경우가 많을수록 해당 전류에 가중치를 크게 둘 수 있다.where the weight by current (

) can be set accordingly by counting the number of times it is operated with the current. That is, as more cases are driven by the current, a greater weight can be given to the current.

The step (S410, S420) of determining whether the idle stop is possible is a first index (A) in which the driving tendency index (K) of the driver calculated based on the driving tendency of the driver learned in the learning step (S300) is preset. If it is above, it may be determined that the idle stop is impossible (S710).

The step (S410, S420) of determining whether an idle stop is possible is a second index (B) in which the driver's driving tendency index (K) calculated based on the driving tendency of the driver learned in the learning step (S300) is preset. If this is the case, it may be determined that a part of the fuel cell stack is capable of an idle stop ( S720 and S730 ). When the driver's driving tendency index K is less than the preset second index B, it may be determined that the entire fuel cell stack is capable of an idle stop ( S740 ).

The fuel cell vehicle of the present invention may be a system having a plurality of fuel cell stacks. A plurality of fuel cell stacks may be provided in a vehicle requiring high power generation output, such as a fuel cell bus. In the present invention, it is assumed that the system has two fuel cell stacks (LH, RH). Each of the fuel cell stacks can be individually controlled to start or stop.

The preset first index (A) may be greater than the preset second index (B). That is, when the driver's driving propensity index (K) is greater than or equal to the preset first index (A), there are many cases where the vehicle starts suddenly after stopping and the required current rises rapidly. Therefore, it is possible to improve drivability by controlling the idle stop to be impossible in all fuel cell stacks.

When the driver's driving propensity index (K) is less than the first index (A) but is the second index (B), it may be determined that a part of the fuel cell stack is capable of an idle stop. That is, in the case of a system having two fuel cell stacks, one of the two fuel cell stacks may activate the idle stop function, and the remaining one may control the idle stop function to be disabled.

After determining whether an idle stop is possible ( S410 and S420 ), determining a deterioration state of the fuel cell stack ( S500 ) further includes; stopping the fuel cell satisfies the entry condition of the idle stop In this case, a portion of the fuel cell stack having a relatively small degree of deterioration calculated based on the determined deterioration state of the fuel cell stack may be stopped ( S720 and S730 ).

As the condition for entering the idle stop, whether to enter the idle stop may be determined according to various conditions such as the amount of current or power required of the fuel cell stack, the amount of charge (SOC) of the high voltage battery, and a deterioration state.

The degree of deterioration calculated based on the deterioration state of the fuel cell stack determined in the steps of determining the deterioration state of the fuel cell stack (S410 and S420) is compared for each stack (S600), and the fuel cell stack having a relatively small deterioration degree is compared for each stack (S600). It is possible to stop a part of (S720, S730). If the fuel cell is controlled by an idle stop, the possibility that the fuel cell stack will be exposed to a high voltage close to OCV increases, and thus there is a high risk of accelerated deterioration. Accordingly, when only a portion of the fuel cell stack is subjected to the idle stop control, the fuel cell stack having relatively less deterioration is controlled to idle stop, thereby preventing acceleration of deterioration of the fuel cell stack in which the deterioration has progressed more.

), 연료전지 출력전류의 크기별로 연속적으로 이용되는 정도를 나타내는 전류 연속이용률(

)을 기반으로 연료전지 스택의 열화 상태를 판단할 수 있다.The step of determining the deterioration state of the fuel cell stack (S410 and S420) is a current utilization ratio (

), the current continuous utilization rate (

), it is possible to determine the deterioration state of the fuel cell stack.

)은 기설정된 기준시간 동안 발생한 연속 사용 시간 중 해당 전류의 최대 연속 사용 시간의 비율일 수 있다. 즉, 전류 연속이용률(

)은 기준시간 이내에 발생한 해당 전류의 최대 연속 사용 시간을 총 연속 사용 시간으로 제산한 값일 수 있다.Current continuous utilization rate (

) may be a ratio of the maximum continuous use time of the current among the continuous use times generated during the preset reference time. That is, the continuous current utilization rate (

) may be a value obtained by dividing the maximum continuous use time of the current generated within the reference time by the total continuous use time.

For example, the degree of deterioration of the fuel cell stack may be calculated using the following equation.

: 전류 이용률,

: 전류 연속이용률, α: 전류 이용률 반영률, β: 전류 연속이용률 반영률,

: Dry-Out 인자C : Degradation degree, m : Number of ranges by size of current, I = Current,

: current utilization,

: Current continuous utilization rate, α: Current utilization rate reflection rate, β: Current continuous use rate reflection rate,

: Dry-Out factor

)는 연료전지 스택의 드라이 아웃을 나타내는 인자일 수 있다. 예를 들면, 기설정된 기준시간 동안 연료전지 스택이 해당 전류일 때의 전압이 드라이 아웃을 판단하는 전압 이하인 개수를 카운팅한 값일 수 있다.Dry-Out factor (

) may be a factor indicating dry-out of the fuel cell stack. For example, it may be a value counting the number of voltages equal to or less than the voltage for determining dry-out when the fuel cell stack is the corresponding current during the preset reference time.

4 is a view illustrating a reflection ratio of a current utilization rate and a continuous current utilization rate for each current magnitude according to an embodiment of the present invention.

)의 반영을 크게 하는 것이 적절하다.Referring to FIG. 4 , it is possible to vary the reflection ratios (α, β) of the current utilization rate and the continuous current utilization rate according to the size of the output current of the fuel cell. Since dry-out due to reversible deterioration often occurs when the magnitude of the fuel cell output current is small, the current utilization rate (

), it is appropriate to increase the reflection of

)의 반영을 크게 하는 것이 적절하다. 다만, 연료전지 출력전류의 크기가 큰 경우에는 가역적 열화에 의한 드라이 아웃도 빈번하게 발생하므로 반영비율 간의 차이는 연료전지 출력 전류의 크기가 작은 경우보다 작을 수 있다.Conversely, when the magnitude of the fuel cell output current is large, dry-out due to irreversible deterioration often occurs. Therefore, the current continuous utilization rate (

), it is appropriate to increase the reflection of However, when the size of the fuel cell output current is large, dry-out due to reversible deterioration also frequently occurs, so the difference between the reflection ratios may be smaller than when the size of the fuel cell output current is small.

5 is a block diagram of a control system for a fuel cell vehicle according to an embodiment of the present invention.

Referring to FIG. 5 , a control system for a fuel cell vehicle according to an embodiment of the present invention includes: a driving tendency determining unit 10 configured to learn a driving tendency of a driver; and an idle stop determination unit ( 30); may include.

Further comprising: a deterioration state determination unit 20 that determines a deterioration state of the fuel cell stack, wherein the idle stop determination unit 30 is configured to determine the state of deterioration of the fuel cell stack when the entry condition of the idle stop is satisfied. A portion of the fuel cell stack having a relatively small degree of deterioration calculated may be stopped.

The driving tendency determining unit 10 , the deterioration state determining unit 20 , and the idle stop determining unit 30 may be configured as separate controllers or may be included as a part of the fuel cell controller (FCU).

Hereinafter, descriptions overlapping with the control method of the fuel cell vehicle will be omitted.

Although shown and described with respect to specific embodiments of the present invention, it is understood in the art that the present invention can be variously improved and changed without departing from the spirit of the present invention provided by the following claims. It will be obvious to those of ordinary skill in the art.

10: driving tendency determination unit 20: deterioration state determination unit
30: idle stop judgment unit

Claims (15)

learning the driving tendency of the driver;
determining whether an idle stop of the fuel cell is possible based on the learned driving tendency; and
When it is determined that the idle stop is possible, stopping the fuel cell when the entry condition for the idle stop is satisfied. The method according to claim 1,
The learning step is a control method of a fuel cell vehicle, characterized in that for learning the driving tendency of the driver based on the output current of the fuel cell for a preset reference time. 3. The method according to claim 2,
The learning step is characterized in that the driver's driving tendency index is calculated based on the current utilization rate indicating the degree of use for each size of the fuel cell output current or the current sudden increase rate indicating the extent of the rapid increase of the output current for each size of the fuel cell output current. A control method for a fuel cell vehicle. 4. The method of claim 3,
The current utilization rate is a control method of a fuel cell vehicle, characterized in that it is a ratio of a time of driving with the current for a preset reference time. 4. The method of claim 3,
The current rapid increase rate is the ratio of the number of times that the current sharp rises in the current range among the number of sudden increases during the preset reference time, and the rapid increase is determined as a sudden increase if the current change rate per hour is greater than or equal to the preset rate of change. Control of a fuel cell vehicle, characterized in that Way. 4. The method of claim 3,
A control method of a fuel cell vehicle, characterized in that the driving tendency index of the driver in the learning step is calculated by the following equation.

K : Driving propensity index, m : Number of ranges by size of current, I = Current,

: current utilization,

: weight by current,

: Current surge rate The method according to claim 1,
The step of determining whether an idle stop is possible is determining that the idle stop is impossible if the driving tendency index of the driver calculated based on the driving tendency of the driver learned in the learning step is equal to or greater than a preset first index. A control method for a battery vehicle. The method according to claim 1,
The step of determining whether an idle stop is possible is a step of determining that a part of the fuel cell stack is capable of an idle stop if the driver's driving tendency index calculated based on the driver's driving tendency learned in the learning step is equal to or greater than a preset second index. A control method of a fuel cell vehicle, characterized in that. 9. The method of claim 8,
After determining whether the idle stop is possible, determining a deterioration state of the fuel cell stack; further comprising,
The step of stopping the fuel cell includes stopping a part of the fuel cell stack having a relatively small degree of degradation calculated based on the determined degradation state of the fuel cell stack when the entry condition for the idle stop is satisfied. control method. 10. The method of claim 9,
The step of determining the deterioration state of the fuel cell stack is based on the current utilization rate indicating the degree of use for each size of the fuel cell output current, and the continuous current utilization rate indicating the degree of continuous use for each size of the fuel cell output current. A control method of a fuel cell vehicle, characterized in that determining a deterioration state. 11. The method of claim 10,
The control method of a fuel cell vehicle, characterized in that the current continuous use rate is a ratio of the maximum continuous use time of the current among the continuous use times generated during the preset reference time. 11. The method of claim 10,
A control method of a fuel cell vehicle, characterized in that the reflection ratio of the current utilization rate and the continuous current utilization rate is varied according to the magnitude of the fuel cell output current. 11. The method of claim 10,
In the step of determining the deterioration state of the fuel cell stack, the degree of deterioration of the fuel cell stack is calculated using the following equation.

C : Degradation degree, m : Number of ranges by size of current, I = Current,

: current utilization,

: Current continuous utilization rate, α: Current utilization rate reflection rate, β: Current continuous use rate reflection rate,

: Dry-Out factor a driving propensity determining unit for learning the driver's driving propensity; and
An idle stop determination unit that determines whether an idle stop of the fuel cell is possible based on the learned driving propensity, and stops the fuel cell if the idle stop entry condition is satisfied when it is determined that the idle stop is possible; A control system for a fuel cell vehicle comprising a. 15. The method of claim 14,
Further comprising; a deterioration state determination unit for determining a deterioration state of the fuel cell stack;
The idle stop determination unit stops a portion of the fuel cell stack having a relatively small degree of deterioration calculated based on the determined deterioration state of the fuel cell stack when the condition for entering the idle stop is satisfied. .

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