SYSTEM AND METHOD FOR CONTROLLING THE PERFORMANCE OF A FUEL CELL

Abstract

Methods for controlling performance, comprising: Measuring, by means of a control system, a temperature of the fuel cell; and If the measured temperature of the fuel cell is within a high-temperature range, in which a fuel cell power threshold is reduced based on an increase in the fuel cell temperature, and if the measured fuel cell temperature is increased and is then equal to or greater than a predetermined temperature, reduce, by controlling, the power threshold from a power value at the predetermined temperature. where the high-temperature range is a range between a third temperature at a power of 70% of an actual power limit, where the power threshold is reduced based on the increase in the temperature of the fuel cell, and a fourth temperature where the power threshold is reduced and then reaches the minimum power threshold of 0%.

Description

BACKGROUND 1. Technical field

[0001] The present invention relates to a system and method for controlling / regulating the power of a fuel cell in order to prevent deterioration and a decrease in the power of the fuel cell, and in particular to a system and method for controlling / regulating the power of a fuel cell in order to prevent the power from changing suddenly. 2. Description of the state of the art

[0002] To prevent a deterioration in the performance of a fuel cell stack, high-temperature operating conditions should be avoided. However, even if the temperature is maintained within a suitable range by a fuel cell cooling control system, the fuel cell temperature can still rise into the high-temperature operating range due to cooling capacity limitations. In particular, a power-limiting method may not be suitable for use under certain circumstances. The present invention proposes a method for optimally limiting power to minimize damage to the operating characteristics and maintain optimal stack performance.In addition to the power limiting image for an operating temperature, features such as preventing power limiting fluctuations, maintaining power limiting start reference consistency, changing a power limiting reference based on an environment and operating state, and the like are used.

[0003] A fuel cell system is configured to include a hydrogen supply system, an air supply system, and a cooling system, and includes a separate fuel cell load device. The cooling system is configured to include a water pump for supplying cooling water, a radiator and radiator fan for heat dissipation from the cooling water, and a thermostat for regulating the amount of water in a cooling circuit and a bypass circuit. The fuel cell load device is used to prevent a build-up of stack voltage during a fuel cell warm-up phase or during start-up / shutdown / shutdown. The fuel cell load device can be a resistor, a rechargeable high-voltage battery, or another load device.

[0004] To regulate the fuel cell temperature, the cooling fan and water pump are operated to prevent the stack temperature from rising to a high temperature (e.g., a predetermined temperature), and the warm-up phase is controlled using the fuel cell load device to prevent the stack temperature from dropping to a specific low temperature. Consequently, even with control / regulation to prevent high / low temperature operation, the temperature may not be maintained within an acceptable range due to limitations in cooling and heating capacity. Therefore, power output is limited depending on the temperature, and thus degradation (e.g.,This prevents overflow at low temperatures, high-temperature drying out, high-temperature degradation, and similar issues with the fuel cell stack. However, when adjusting the stack's power output based on temperature, performance may fluctuate, drivability may be reduced, and fuel cell degradation may not be effectively prevented in advance.

[0005] From US 2013 / 0 323 540 A1, a method for controlling the power is known, comprising: measuring, by means of a control, a temperature of the fuel cell;and if the measured temperature of the fuel cell is within a high-temperature range in which a fuel cell power threshold is reduced based on an increase in the fuel cell temperature, and if the measured fuel cell temperature is increased and is then equal to or greater than a predetermined temperature, reduce, by controlling, the power threshold from a power value at the predetermined temperature, wherein the predetermined high-temperature range is a range between a third temperature at which the power threshold is reduced based on the increase in the fuel cell temperature, and a fourth temperature at which the power threshold is reduced and then reaches the minimum power threshold.

[0006] The items described as prior art are provided only to promote an understanding of the background of the present invention and should not be regarded as corresponding to the prior art known to a person skilled in the art. OVERVIEW

[0007] It is an object of the present invention to provide a system and method for controlling / regulating the power of a fuel cell in order to prevent deterioration and a decrease in the power of the fuel cell, and in particular a system and method for controlling / regulating the power of a fuel cell in order to prevent the power from changing suddenly.

[0008] The problem is solved by a method for controlling the power with the features of claim 1 and a system for controlling the power of a fuel cell with the features of claim 18. Advantageous further developments are found in the dependent claims.

[0009] According to an embodiment of the present invention, a method for controlling / regulating the power comprises: measuring a temperature of the fuel cell; and if the measured temperature of the fuel cell is within a predetermined high-temperature range, a power threshold of the fuel cell is reduced based on an increase in the temperature of the fuel cell, and if the measured temperature of the fuel cell is increased and is then equal to or greater than a predetermined temperature, reducing a power threshold from a power value at the predetermined temperature.The high-temperature range is a range between a third temperature at a power of 70% of an actual power limit, where the power threshold is reduced based on the increase in the temperature of the fuel cell, and a fourth temperature where the power threshold is reduced and then reaches the minimum power threshold of 0%.

[0010] Reducing the power threshold can further include reducing the fuel cell power threshold between a maximum power threshold based on the increase in the measured fuel cell temperature and a power value at a fifth temperature, if the measured fuel cell temperature is within the range of the fifth temperature, which is preset, such that it is greater than the third temperature but less than the fourth temperature. Reducing the power threshold can further include reducing the fuel cell power threshold between the power value at the fifth temperature and the minimum power threshold if the measured fuel cell temperature is greater than the fifth temperature, which is preset, such that it is greater than the third temperature but less than the fourth temperature.

[0011] The method may further include: setting the fuel cell power threshold to a minimum value when the measured fuel cell temperature is above the high-temperature range. Furthermore, the method may include: increasing the fuel cell power threshold based on the increase in fuel cell temperature when the measured fuel cell temperature is within a predetermined low-temperature range. The low-temperature range may be a range between an initial temperature at which the fuel cell power threshold is held essentially constant and then begins to increase, and a second temperature at which the power threshold is increased and then reaches the maximum power threshold.The procedure may further include: setting the power threshold of the fuel cell to a first output threshold greater than a minimum output threshold within the high-temperature range when the measured temperature of the fuel cell is less than the low-temperature range.

[0012] The initial output threshold can be adjusted upwards (e.g., an increase can be set) if the measured fuel cell temperature is maintained at or above a reference value for a reference period. The procedure can further include: setting the fuel cell power threshold to remain substantially constant when the measured temperature is within a preset limit temperature range, even if the measured fuel cell temperature is within the high-temperature range.

[0013] The adjustment may include increasing the power threshold if the fuel cell power threshold is kept essentially constant during the decrease in the measured fuel cell temperature and then deviates from the limit temperature range when the measured fuel cell temperature is within the high temperature range and within the preset limit temperature range, and decreasing the fuel cell power threshold if the fuel cell power threshold is kept essentially constant and then deviates from the limit temperature range when the measured fuel cell temperature is increased.

[0014] Additionally, the procedure may further include: adjusting the power threshold of the fuel cell to be kept substantially constant when the measured temperature is within a preset limit temperature range, even if the measured temperature of the fuel cell is within the low temperature range.The adjustment may include increasing the power threshold if the fuel cell power threshold is kept essentially constant during an increase in the measured fuel cell temperature and then deviates from the limit temperature range when the measured fuel cell temperature is within the low temperature range and within the preset limit temperature range, and decreasing the power threshold if the fuel cell power threshold is kept essentially constant and then deviates from the limit temperature range when the measured fuel cell temperature is decreased.

[0015] The high-temperature range can change based on an ambient temperature and an incline (e.g., the gradient of a road on which a vehicle is traveling forward) or the operating speed of the fuel cell for a vehicle. The third or fifth temperature, which is set so that it is higher than the third temperature but lower than the fourth temperature, can be adjusted downwards (e.g., a reduction set) if the vehicle speed decreases, the ambient temperature increases, or the incline increases.The third or fifth temperature, which is preset to be higher than the third temperature but lower than the fourth, can be adjusted downwards if the measured fuel cell temperature is maintained at or above the third temperature for a predetermined time and if the vehicle speed decreases, the ambient temperature increases, or the incline angle increases. The low-temperature range may change based on whether the fuel cell stack is warmed up before operation.

[0016] If the time period during which the measured fuel cell temperature is equal to or greater than the second temperature exceeds a predetermined time, the first or second temperature can be adjusted downwards, or a first power threshold greater than a minimum power threshold within the high-temperature range can be increased. A target operating temperature, which is a reference temperature used to set the revolutions per minute (rpm) of a cooling water pump, the speed of a radiator fan, or the opening of a thermostat, can be changed based on a change in the high-temperature range. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The above and further tasks, features and advantages of the present invention will become clearer from the following detailed description in conjunction with the accompanying drawings. The figures show: Fig. 1. An exemplary graph to describe a method for controlling / regulating the power of a fuel cell according to a comparative example of the state of the art; Fig. 2 an exemplary graph to describe a method for controlling / regulating the power of a fuel cell according to an embodiment of the present invention; Fig. 3 and Fig. 4 exemplary flowcharts of the method for controlling the power of a fuel cell according to the embodiment of the present invention; Fig. 5 an exemplary graph for a usage result of the method for controlling / regulating the power of a fuel cell according to a comparative example of the state of the art; Fig. 6 an exemplary graph for a usage result of the method for controlling / regulating the power of a fuel cell according to the embodiment of the present invention; Fig. 7 and Fig. 8 exemplary graphs for a comparison result of the method for controlling / regulating the power of a fuel cell according to the embodiment of the present invention and a comparison example; Fig. 9 an exemplary diagram describing a cooling control associated with a power control according to the embodiment of the present invention; Fig. 10A and Fig. 10B Exemplary graphs showing a current limiting reference temperature tendency as a function of vehicle speed and outside temperature in the method for controlling / regulating power according to the embodiment of the present invention; Fig. 11 an exemplary diagram illustrating a state-of-the-art fuel cell system of a vehicle; and Fig. 12 an exemplary graph which represents an example in which a target operating temperature, which is a reference temperature that sets a speed (rpm) of a cooling water pump, speed (rpm) of a radiator fan or opening of a thermostat, is changed depending on a change in a high temperature range. DETAILED DESCRIPTION

[0018] It is understood that the term "vehicle" or "vehicle-" or other equivalent expressions as used herein include motor vehicles in general, such as passenger cars including sports utility vehicles (SUVs), buses, trucks, various utility vehicles, watercraft including a variety of boats and ships, aircraft and the like, and include hybrid vehicles, electric vehicles, plug-in hybrid electric vehicles, hydrogen-powered vehicles and other vehicles using alternative fuels (for example, fuel derived from sources other than petroleum). As referenced herein, a hybrid vehicle is a vehicle that has two or more sources of propulsion, such as both gasoline-powered and electric-powered vehicles.

[0019] Although the exemplary embodiment is described as using a plurality of units to perform the exemplary process, it is understood that the exemplary processes can also be performed by one or more modules. Furthermore, it is understood that the term "controller" refers to a hardware device comprising a memory and a processor. The memory is configured to store the modules, and the processor is specifically configured to execute said modules to perform one or more processes, which are described below.

[0020] Furthermore, the control logic of the present invention can be implemented as non-volatile, computer-readable media on a computer-readable medium comprising executable program instructions that are executed by a processor, a controller / control unit, or the like. Examples of computer-readable storage media include, but are not limited to, ROM, RAM, compact disc (CD)-ROMs, magnetic tapes, floppy disks, flash drives, smart cards, and optical data storage devices. The computer-readable recording medium can also be decentralized in networked computer systems, such that the computer-readable medium is stored and executed in a distributed manner, e.g., by a telematics server or a controller area network (CAN).

[0021] The terminology used herein is intended for the purpose of describing certain embodiments and is not intended to limit the invention. As used herein, the singular forms "a," "an," and "the" are intended to include the plural forms unless the context clearly indicates otherwise. It is further understood that the expressions "possess" and / or "possessing," when used in this description, describe the presence of the specified features, numbers, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more features, numbers, steps, operations, elements, components, and / or groups thereof. As used herein, the expression "and / or" includes any and all combinations of one or more of the associated listed elements.

[0022] Unless expressly stated otherwise or evident from the context, the term "approximately" as used herein is understood to mean that the value lies within a range of standard tolerances in the prior art, for example, within two standard deviations of the mean values. "Approximately" may be understood to mean that the value lies within 10%, 9%, 8%, 7%, 6%, 5%, 4%, 3%, 2%, 1%, 0.5%, 0.1%, 0.05%, or 0.01% of the stated value. Unless otherwise indicated by the context, all numerical values ​​provided herein are modified by the term "approximately".

[0023] Exemplary embodiments of the present invention are described below with reference to the accompanying drawings.

[0024] Fig. Figure 1 shows a graph to describe a method for controlling / regulating the power of a fuel cell according to a comparative example. Fig. Figure 2 shows a graph to describe a method for controlling / regulating the power of a fuel cell according to an embodiment of the present invention. Fig. 3 and Fig. 4 show flowcharts of the method for controlling the power of a fuel cell according to the embodiment of the present invention, Fig. Figure 5 shows a graph for a usage result of the method for controlling / regulating the power of a fuel cell according to a comparative example. Fig. Figure 6 shows a graph for a usage result of the method for controlling / regulating the power of a fuel cell according to the embodiment of the present invention. Fig. 7 and Fig. Figure 8 shows graphs for a comparison result of the method for controlling / regulating the power of a fuel cell according to the embodiment of the present invention and a comparison example. Fig. Figure 9 shows a diagram describing a cooling control system associated with a power control system according to the embodiment of the present invention, and Fig. 10A and Fig. Figure 10B shows graphs illustrating a current limiting reference temperature tendency as a function of vehicle speed and outside temperature in the method for controlling / regulating power according to the embodiment of the present invention. Fig. Figure 11 shows a diagram illustrating a state-of-the-art fuel cell system of a vehicle and Fig. Figure 12 shows a graph that represents an example in which a target operating temperature, which is a reference temperature that sets a speed (rpm) of a cooling water pump, speed (rpm) of a radiator fan or the opening of a thermostat, is changed depending on a change in a high temperature range.

[0025] In particular, it shows Fig. Figure 11 shows a diagram representing a vehicle fuel cell system, wherein the fuel cell system comprises a hydrogen supply system, an air supply system, a cooling system, and a separate fuel cell load device 500. The cooling system includes a water pump 310 configured to supply cooling water, a radiator and a radiator fan 300 for heat dissipation from the cooling water, and a thermostat 320 configured to measure the temperature of the cooling water and to regulate the amount of water in a radiator circuit and a bypass circuit. The fuel cell load device 500 can be used as a device to prevent a stack voltage from increasing during a fuel cell warm-up phase or during start-up / shutdown.An air blower 100 can be configured to supply air to a stack 200, and a hydrogen valve 400 can be configured to supply hydrogen to the stack 200 or to block the supply. The temperature of the fuel cell can be measured in various ways, but can be determined by measuring the temperature of the cooling water used to cool the fuel cell, and the power output of the fuel cell can be limited by setting a voltage and current based on an adjustment of the air supply or hydrogen supply.

[0026] The comparative example of the prior art that can be compared with the present invention is first described with reference to Fig. 1 described. In the comparative example of Fig. 1. If the measured temperature of the fuel cell is equal to or less than a first temperature, the fuel cell's power output is set to a first power threshold. If the measured temperature of the fuel cell ranges from the first temperature to a second temperature, as the temperature increases, the fuel cell's power threshold (e.g., power limit) can be increased between the first power threshold and a maximum power threshold. Furthermore, since the measured temperature of the fuel cell ranges from the second temperature to a third temperature, which corresponds to a normal range, the fuel cell's temperature can be adjusted to produce a power output approximately equal to 100% of the fuel cell's power threshold, because the power output is not specifically limited.

[0027] Meanwhile, if the measured temperature of the fuel cell falls within a range defined by the third and fourth temperatures (e.g., a predefined high-temperature range), and the fuel cell temperature is increased, the power threshold of the fuel cell can be lowered between a current power value and a minimum power threshold. If the fuel cell temperature is equal to or greater than the fourth temperature, i.e., exceeding the high-temperature range, the fuel cell temperature can be classified as an ultra-high temperature range, thus halting fuel cell operation. In this case, the fuel cell's power threshold can be set to the minimum power threshold (e.g., approximately 0%).

[0028] Furthermore, to regulate the fuel cell temperature, a control system can be set up to operate the cooling fan and water pump to prevent the stack from heating up to a predetermined high temperature, and warm-up control can be implemented using the fuel cell load device to prevent the stack from cooling down to a predetermined low temperature. Consequently, even if the control system is set up to prevent the stack from reaching high-temperature or low-temperature operation, the temperature may not be maintained within a suitable range due to limitations in cooling and heating capacity. As a result, as illustrated by the comparative example of Fig. 1. A method for limiting power based on temperature can be considered to prevent stack deterioration (e.g., preventing low-temperature overflow, high-temperature drying out, high-temperature degradation, and the like). Specifically, since a temperature-based power limiting map can be used, the power limit may vary / fluctuate based on the changing temperature, and thus drivability / handling may deteriorate (e.g., due to fluctuations). Meanwhile, the first temperature may be 15 degrees Celsius, the second temperature 55 degrees Celsius, the third temperature 72 degrees Celsius, the fourth temperature 82 degrees Celsius, and the fifth temperature 77 degrees Celsius.The high temperature can be the third temperature or higher, and the low temperature can be the second temperature or lower.

[0029] The present invention is described with reference to Fig. 2 to 4 described. The system and method for controlling / regulating the power of a fuel cell according to the embodiment of the present invention can include setting the power threshold of the fuel cell based on the measured temperature of the fuel cell. In particular, the method described below can be carried out by a controller with a processor and a memory. Additionally, the various detected temperatures can be measured using a temperature sensor.

[0030] First, if the fuel cell temperature is equal to or less than the first temperature recorded by measuring the fuel cell temperature (S10), a low-temperature step (S12) can be performed, which sets the fuel cell power to a first power threshold (S14). In other words, if the measured fuel cell temperature is less than a low-temperature range (e.g., a temperature range between the first and second temperatures), the fuel cell power threshold can be set / fixed to the first power threshold. As in Fig. As shown in Figures 2 to 4, the first power threshold can be set to be greater than the minimum power threshold in the high-temperature range (e.g., a temperature range between the third and fourth temperatures). The low-temperature range can be a temperature range between the first temperature, at which the fuel cell's power threshold can be kept essentially constant and then begins to increase, and the second temperature, at which the power threshold increases and then reaches the maximum power threshold.

[0031] If the fuel cell temperature is maintained at or above a reference value for a reference period, the first temperature can be adjusted downwards (e.g., set to decrease or be reduced), as shown in a left-shifted graph of Fig. Figure 2 illustrates this. In other words, the first temperature can be reduced to the first temperature', and the second temperature can be reduced to the second temperature'. Furthermore, if the fuel cell temperature is maintained at or above the reference value for a reference period, the first power threshold can be adjusted upwards (e.g., adjusted / set so that it is increased). In other words, when limiting the low-temperature power, the low-temperature power limit after the fuel cell warm-up phase can be reduced. Consequently, in response to a requirement that the fuel cell warms up for a predetermined period after the cooling pump is driven (e.g., if the fuel cell temperature is maintained at or above the reference value for the reference period), the first temperature and the first power threshold can be modified.

[0032] However, if the measured temperature of the fuel cell lies in the range from the first temperature to the second temperature (e.g., the low-temperature range) (S20), a medium-low temperature step (S22) can be performed to determine the power threshold of the fuel cell using a graph with an increasing gradient between the first power threshold and the maximum power threshold. Furthermore, the medium-low temperature step includes a graph that incorporates a hysteresis (H) section before and after the first and second temperatures, and the increasing gradient is formed from a rising graph (e.g., an increasing graph) and a falling graph (e.g.,a decreasing graph) at an upper or lower limit of the hysteresis loop, thus preventing the fuel cell's power threshold from changing abruptly based on a change in the fuel cell's temperature. Even if the measured fuel cell temperature is within the low-temperature range, if the measured temperature is within a preset temperature range, the fuel cell's power threshold can be set so that it is essentially kept constant.

[0033] In other words, since the power limiting map is temperature-based, the power limit can also fluctuate based on temperature variations (e.g., variance), thus potentially impairing drivability. To minimize power fluctuations, hysteresis can be applied within the limit temperature range based on temperature changes. For temperature changes within the hysteresis band, the power threshold can be maintained, thereby mitigating power fluctuations. By differentiating the band during temperature increases and decreases, power can be directly limited during temperature increases within the high-temperature power limiting range, while the power limit recovery during temperature decreases can be gradual (e.g., reduced).

[0034] However, a rate of increase over time can be added to the power limit, thus minimizing fluctuations in the power limit over time. In other words, if the measured fuel cell temperature is within a low-temperature range and within the preset limit temperature range, the power threshold can be increased if it remains essentially constant during the increase in the measured fuel cell temperature and then deviates from the limit temperature range. Conversely, the power threshold can be decreased if it remains essentially constant during the decrease in the measured fuel cell temperature and then deviates from the limit temperature range.

[0035] Therefore, as shown, in the medium-low temperature step, a graph is formed that exhibits the hysteresis H section, which is the limit temperature range provided before and after the first and second temperatures, and the increasing gradient, consisting of a rising graph u and a falling graph d at the upper and lower limits of the hysteresis section, respectively. If the fuel cell temperature is maintained at or above the reference value for the reference period, it can be determined that the fuel cell is sufficiently warmed up, and thus the graph can be shifted to u1 and d1, and simultaneously the first power threshold can also be raised to the second power threshold.Furthermore, if the measured temperature of the fuel cell is in the range from the second temperature to the third temperature (S30), a mean temperature step (S32) can be performed to adjust the power threshold of the fuel cell to the maximum power threshold.

[0036] However, if the measured temperature of the fuel cell is in the range from the third temperature to a fifth temperature (S40), a medium-high temperature step (S44) can be performed to determine the power threshold (e.g., third temperature, maximum power threshold: 100%) of the fuel cell using the graph with the falling gradient connecting two points (e.g., fifth temperature, actual power value). Specifically, the power threshold of the fuel cell, which is held at approximately 100%, can be reduced to the actual power value based on the temperature. Furthermore, if the measured temperature of the fuel cell is equal to or greater than the fifth temperature, a high-temperature step can be performed to determine the power threshold of the fuel cell using a graph with the falling gradient between the actual power value and a minimum power threshold.

[0037] In other words, if the measured temperature of the fuel cell is within the high-temperature range, the power threshold of the fuel cell can be reduced based on the increase in the fuel cell temperature. If the measured temperature of the fuel cell is increased and is then equal to or greater than a predetermined temperature, the power threshold can be directly reduced from the power value at the predetermined temperature.

[0038] In particular, the high-temperature range can be a temperature range between the third temperature, at which the power threshold begins to decrease based on the increase in fuel cell temperature, and the fourth temperature, at which the power threshold decreases and then reaches the minimum power threshold. If the measured fuel cell temperature is the fifth temperature, which is preset to be higher than the third temperature and lower than the fourth temperature, the power threshold can be reduced between the maximum power threshold based on the increase in the measured fuel cell temperature and the power value of the fifth temperature.Furthermore, if the measured temperature of the fuel cell is greater than the fifth temperature, which is preset so that it is greater than the third temperature and less than the fourth temperature, the power threshold of the fuel cell can be reduced between the power value at the fifth temperature and the minimum power threshold.

[0039] Furthermore, if the fuel cell temperature is in the range from the fifth temperature to the fourth temperature (S50), the high-temperature step can be performed to adjust the fuel cell power threshold to exhibit the decreasing gradient between the actual power value and the minimum power threshold (0%). Conversely, if the fuel cell temperature is equal to or greater than the fourth temperature, the high-temperature step can be performed to limit the fuel cell power to approximately 0% (S54). In other words, if the measured fuel cell temperature exceeds the high-temperature range, the fuel cell power threshold can be set to the minimum value.

[0040] Furthermore, similarly, if the temperature of the fuel cell is within the low-temperature range, even if the measured temperature of the fuel cell is within the high-temperature range, if the measured temperature is within the preset limit temperature range, the power threshold of the fuel cell can be kept essentially constant.In other words, if the measured temperature of the fuel cell is within the high-temperature range and within the preset limit temperature range of the high-temperature range, if the power threshold of the fuel cell is kept essentially constant during the decrease in the measured temperature of the fuel cell and then deviates from the limit temperature range, the power threshold can be increased; and if the measured temperature of the fuel cell is increased, if the power threshold of the fuel cell is kept essentially constant and then deviates from the limit temperature range, the power threshold of the fuel cell can be decreased.

[0041] In particular, in the medium-high temperature step (S44), the actual power (actual power) can be continuously sampled / captured in real time and thus continuously updated (S42), and in the high-temperature step, the current-limiting image can be determined based on the actual power, which is ultimately recorded in the medium-high temperature step. Furthermore, even in the medium-high temperature step, an equation is set up so that if the temperature is less than the fifth temperature, the power threshold is adjusted to be greater than the actual power.For example, in this section, where the temperature continuously increases in the medium-high temperature step, if the difference between the power threshold and the actual power is gradually / stepwise reduced, and then the temperature reaches the fifth temperature, the difference becomes approximately 0, and thus the power threshold can be the actual power, and if the value is stored and the high-temperature step is performed, the power threshold can be reduced from the stored power value to approximately 0%.

[0042] With reference to Fig. 4. It can be determined whether the fuel cell temperature is greater than the third temperature (S401), and in response to a determination that the fuel cell temperature is greater than the third temperature, it can be determined whether the current limiting temperature is greater than the fifth temperature (S403). In response to a determination that the fuel cell temperature is less than the third temperature, Mode 1, which maintains the maximum power threshold, can be performed (S405). In response to a determination that the current limiting temperature is greater than the fourth temperature, based on whether the current limiting temperature is greater than the fifth temperature, the actual power value of the fuel cell does not necessarily need to be updated (S407).Furthermore, in response to a determination that the current limiting temperature is less than the fifth temperature, the actual power value of the fuel cell does not necessarily need to be updated and recorded (S409). In particular, the power threshold can be a value between the maximum power threshold and the actual power value, which is referred to as Mode 2 (S411). The power threshold can be a minimum value between the actual power + K * (fourth temperature - actual temperature) and the maximum power threshold.

[0043] Furthermore, the actual power value of the fuel cell does not necessarily need to be updated (S407), and it can be determined again whether the current-limiting temperature is equal to or greater than the fourth temperature (S413). In response to a determination that the current-limiting temperature is equal to or greater than the fourth temperature, the power threshold can be reduced to approximately 0%, which is referred to as Mode 4 (S415). In response to a determination that the current-limiting temperature is less than the fifth temperature, the power threshold can be a value between the actual power and approximately 0%. As the temperature increases, the power threshold follows a curve that decreases from the finally recorded actual power value to 0%, which is referred to as Mode 3 (S417).

[0044] In Mode 2, the actual power can be continuously sampled / captured in real time and updated, while in Mode 3, a current limiting image can be determined based on the actual power, which is ultimately recorded in Mode 2. This is the actual power when the temperature reaches the fourth temperature. For example, in the section where the temperature continuously increases, in Mode 2, as the difference between the power threshold and the actual power gradually decreases and the temperature reaches the fifth temperature, the difference becomes 0. Therefore, the power threshold can be the actual power. If this value is saved and Mode 3 is executed, the power threshold can be reduced from the saved power value to approximately 0%.

[0045] In the comparative example of Fig. 1. If the power is limited, starting from 100%, which is the maximum power threshold during high temperatures, and thus the power is reduced to a low power level, the actual power input reference temperature can occur (e.g., as in Fig. Figure 1 shows that when the temperature reaches the third temperature at approximately 70% power, the actual power limit begins at a higher temperature than the third temperature. Therefore, according to the embodiment of the present invention, as shown in Figure 1, the following applies: Fig. Figure 2 shows that the power output is rapidly limited by the actual power at which the high temperature is generated, in order to maintain consistency between the power input and reference temperature. This allows the actual power output to be limited by the fifth temperature regardless of the magnitude of the actual power output. As a result, the range in which the stack unexpectedly operates at high temperatures can be minimized.

[0046] However, when limiting the power output at high temperature, a convergence power deviation can occur due to a difference in the maximum amount of thermal radiation (e.g., environmental factors such as the ambient temperature and the slope / gradient). If the temperature converges at low / medium power, a humidification situation can be exacerbated because the water production from the fuel cell is insufficient. Consequently, the deterioration of the fuel cell can be further accelerated, potentially leading to irreversible failure.

[0047] In other words, the third and fourth temperatures, which are the reference temperatures for the high-temperature range, can be adjusted for a vehicle based on the ambient temperature and an inclination angle (e.g., a road gradient) or the fuel cell's operating speed. The third or fifth temperature can be adjusted downwards (e.g., reduced) if the vehicle speed decreases, the ambient temperature increases, or the inclination angle becomes significant (e.g., greater than a predefined angle). Furthermore, the third or fifth temperature can be adjusted downwards if the measured fuel cell temperature is equal to or greater than the third temperature and remains constant for a predefined period, and if the vehicle speed decreases, the ambient temperature increases, or the inclination angle becomes significant.

[0048] To improve humidification, the high-temperature power limit reference temperature should be reduced. The maximum thermal radiative power of the fuel cell depends on the thermal radiative power of the cooler and can be modified based on environmental factors, such as high ambient temperature and a limitation of the airflow speed due to the vehicle's incline, excluding design factors. Among the environmental factors, ambient temperature and vehicle speed can be selected based on a variable reference. Furthermore, other factors influencing the maximum thermal radiative power can be considered. For example, if the incline angle is increased, the reference temperature incline value can be increased.

[0049] Consequently, the third and fifth temperatures can be adjusted downwards (e.g., reduced) if the vehicle speed decreases or the outside temperature increases. Furthermore, even in the medium-high temperature step, the graph, which includes the hysteresis section before and after the third and fifth temperatures and the falling gradient, is formed from a falling graph d' and a rising graph u' at an upper and lower limit point, respectively, of the hysteresis section. This prevents the fuel cell's power threshold from being abruptly changed based on a change in the fuel cell's temperature, and transitions to a u1' and d1' graph during a vehicle shift.

[0050] Furthermore, even in the high-temperature step, the graph that exhibits the hysteresis section after and before the fifth temperature and the falling gradient is formed from the falling graph and the rising graph at the upper limit point and the lower limit point of the hysteresis section, respectively, thus preventing the power threshold of the fuel cell from being suddenly changed based on the change in the temperature of the fuel cell.

[0051] Fig. Figure 5 shows a graph for a usage result of the method for controlling / regulating the power of a fuel cell according to a comparative example of the state of the art and Fig. Figure 6 shows a graph for a usage result of the method for controlling / regulating the power of a fuel cell according to the embodiment of the present invention, wherein, in comparison with the comparison example according to the embodiment of the present invention, the fluctuation of the stack current can be substantially reduced, so that drivability can be improved.

[0052] Fig. 7 and Fig. Figure 8 shows graphs for a comparison result of the method for controlling / regulating the power of a fuel cell according to the embodiment of the present invention and the comparison example, wherein the power and the vehicle speed are shown during the high-temperature incline operation and the temperature power limitation is applied at the low / medium power due to the limitation of the thermal radiation power (e.g., the outside temperature is high and the wind resistance is minimal).

[0053] In the comparative example, compared to operation in a lowland area (flat terrain) or a low-temperature environment, the fuel cell's convergence performance may be reduced in the high-temperature operating state, and the production of water required for humidification may be insufficient, thus further exacerbating the humidification situation. Consequently, both the voltage and current may decrease due to the performance degradation, and the power output may be reduced, thus reducing the vehicle's speed.

[0054] Furthermore, to prevent a deterioration of the humidification situation, as in the embodiment of the present invention, if the temperature current limit is limited in advance based on the external environment, such as vehicle speed, ambient temperature, and angle of inclination, the vehicle speed can be reduced due to the temporary power limitation, but the current / voltage characteristics of the fuel cell can be maintained for a substantial period of time, so that it can be recognized that the final vehicle speed can be maintained or increased. In other words, the core of the present invention is to prevent the deterioration of the fuel cell's performance by pre-detecting situations in which the humidification situation of the fuel cell may deteriorate.

[0055] Fig. 10A and Fig. Figure 10B shows graphs illustrating a current-limiting reference temperature tendency based on a vehicle speed and an outside temperature in the method for controlling / regulating the power according to the embodiment of the present invention. With reference to Fig. 10A and Fig. 10B allows the reference temperature slope for power limitation to be decreased based on increasing vehicle speed and increased based on increasing ambient temperature. In other words, the power limitation reference temperature can be adjusted within the high-temperature range so that it is lower or higher when the amount of airflow changes due to ambient temperature, slope, or vehicle speed. Furthermore, other factors affecting maximum thermal radiative power can be taken into account.

[0056] According to the procedure for limiting the power of a vehicle's fuel cell, as described above, it may be possible to prevent sudden changes in power during the limiting process, thus preventing deterioration and performance degradation of the fuel cell. Furthermore, it may be possible to ensure consistent start timing for the power limitation and to effectively limit the power by actively responding to changes in the external environment.

[0057] Fig. Figure 9 shows a diagram describing a cooling control system connected with a power control system according to the embodiment of the present invention. With reference to Fig. 9. When the power limit reference temperature is changed, a proportional-integral (PI) control reference of the cooling water pump can be changed. In other words, if the power limit reference temperature is decreased, a cooling water setpoint temperature of an inlet of the stack can also be set to decrease. If the power limit reference temperature increases, the cooling water setpoint temperature of the inlet of the stack can be set to increase, as described in Fig. 2 is described.

[0058] Fig.Figure 12 shows a graph illustrating an example where a target operating temperature, which is a reference temperature that sets the speed (rpm) of a coolant pump, the speed (rpm) of a radiator fan, or the opening of a thermostat, is changed depending on a change in a high-temperature range. In other words, the high-temperature range can be changed based on a change in at least one of the vehicle speed, the ambient temperature, and the angle of inclination, and when the high-temperature range is changed, the increment of the cooling control temperature can be changed. As the coolant pump and radiator fan operate for each temperature increment, the target operating temperature (e.g., TH1 °C to TH7 °C), which is the reference temperature for the cooling control, can also be changed.The related objects / matters are disclosed in the Koranic patent application KR 10 2012 0 053 137 A, and therefore a detailed description of the drawings is omitted. However, a feature of the present invention is that the cooling control is carried out to change the target operating temperature based on changes in the temperature range for the power threshold.

[0059] According to the fuel cell power control procedure set up as described above, it may be possible to prevent sudden changes in power when limiting the fuel cell's output, thus preventing deterioration and performance degradation. Furthermore, it may be possible to ensure consistent power limit start timing and effective power limitation by actively addressing changes in the external environment.

Claims

[1] A method for controlling performance, comprising: Measuring, by means of a control system, a temperature of the fuel cell; and If the measured temperature of the fuel cell is within a high-temperature range, in which a fuel cell power threshold is reduced based on an increase in the fuel cell temperature, and if the measured fuel cell temperature is increased and is then equal to or greater than a predetermined temperature, reduce, by controlling, the power threshold from a power value at the predetermined temperature. where the high-temperature range is a range between a third temperature at a power of 70% of an actual power limit, where the power threshold is reduced based on the increase in the temperature of the fuel cell, and a fourth temperature where the power threshold is reduced and then reaches the minimum power threshold of 0%. [2] Method according to claim 1, wherein reducing the performance threshold further comprises: Reducing, by controlling, the power threshold of the fuel cell between a maximum power threshold based on the increase in the measured temperature of the fuel cell and a power value of a fifth temperature, when the measured temperature of the fuel cell is in the range of the fifth temperature, which is preset so that it is greater than the third temperature and less than the fourth temperature. [3] Method according to claim 1, wherein reducing the performance threshold further comprises: Reduce, by controlling, the power threshold of the fuel cell between a power value at a fifth temperature and the minimum power threshold when the measured temperature of the fuel cell is greater than the fifth temperature, which is preset so that it is greater than the third temperature and less than the fourth temperature. [4] Method according to claim 1, further comprising: By controlling the fuel cell, set the power threshold to a minimum value when the measured temperature of the fuel cell is greater than the high-temperature range. [5] Method according to claim 1, further comprising: Increase, by controlling, the power threshold of the fuel cell based on the increase in the temperature of the fuel cell, when the measured temperature of the fuel cell is within a predetermined low-temperature range, where the low-temperature range is a range between a first temperature at which the power threshold of the fuel cell is essentially kept constant and then begins to increase, and a second temperature at which the power threshold is increased and then reaches a maximum power threshold. [6] Method according to claim 5, further comprising: Setting, by controlling, the power threshold of the fuel cell to a first output threshold greater than the minimum output threshold within the high-temperature range when the measured temperature of the fuel cell is less than the low-temperature range. [7] Method according to claim 6, wherein the first initial threshold is increased when the measured temperature of the fuel cell is equal to or greater than a reference value for a reference time. [8] Method according to claim 1, further comprising: Adjusting, by controlling, the power threshold of the fuel cell to be kept essentially constant when the measured temperature is within a preset limit temperature range and the measured temperature of the fuel cell is within the high temperature range. [9] Method according to claim 8, wherein the setting comprises: Increase, by controlling, the power threshold if the fuel cell power threshold is kept substantially constant during a decrease in the measured fuel cell temperature and then deviates from the limit temperature range when the measured fuel cell temperature is within the high-temperature range and within the preset limit temperature range; and Reducing, by controlling, the power threshold of the fuel cell, if the power threshold of the fuel cell is kept essentially constant and then deviates from the limit temperature range when the measured temperature of the fuel cell is increased. [10] Method according to claim 5, further comprising: Adjusting, by controlling, the power threshold of the fuel cell to be kept essentially constant when the measured temperature is within a preset limit temperature range and the measured temperature of the fuel cell is within the low temperature range. [11] Method according to claim 10, wherein the setting comprises: Increase, by controlling, the power threshold if the fuel cell power threshold is kept substantially constant during the increase in the measured fuel cell temperature and then deviates from the limit temperature range when the measured fuel cell temperature is within the low-temperature range and within the preset limit temperature range; and Reducing, by controlling, the power threshold if the power threshold of the fuel cell is kept essentially constant and then deviates from the limit temperature range when the measured temperature of the fuel cell is reduced. [12] Method according to claim 1, wherein the high temperature range is changed based on an outside temperature and an inclination angle or an operating speed of the fuel cell for a vehicle. [13] Method according to claim 12, wherein the third temperature or a fifth temperature, which is set so that it is greater than the third temperature and less than the fourth temperature, is reduced when a vehicle speed is reduced, the outside temperature increases or when the angle of inclination increases. [14] Method according to claim 12, wherein the third temperature or a fifth temperature, which is preset to be greater than the third temperature and less than the fourth temperature, is reduced when the measured temperature of the fuel cell is maintained at the third temperature or greater for a predetermined time and when a vehicle speed is reduced, the outside temperature increases or the angle of inclination increases. [15] Method according to claim 5, wherein the low temperature range is changed based on whether a fuel cell stack is heated before it is operated. [16] Method according to claim 15, wherein if the time period during which the measured temperature of the fuel cell is kept equal to or greater than the second temperature exceeds a predetermined time, the first temperature or the second temperature is reduced or a first power threshold greater than the minimum power threshold within the high-temperature range is increased. [17] Method according to claim 12, wherein a target operating temperature, which is a reference temperature that sets the revolutions per minute (rpm) of a cooling water pump, rpm of a radiator fan or the opening of a thermostat, is changed based on a change in the high temperature range. [18] System for controlling the power output of a fuel cell, comprising: a memory set up to store program instructions; and a processor configured to execute the program instructions, wherein the program instructions, when executed, are configured to: to measure the temperature of the fuel cell; and to reduce the power threshold from a power value at the specified temperature if the measured temperature of the fuel cell is within a high-temperature range in which a power threshold of the fuel cell is reduced based on an increase in the temperature of the fuel cell, and if the measured temperature of the fuel cell is increased and is then equal to or greater than a specified temperature, where the high-temperature range is a range between a third temperature at a power of 70% of an actual power limit, where the power threshold is reduced based on the increase in the temperature of the fuel cell, and a fourth temperature where the power threshold is reduced and then reaches the minimum power threshold of 0%. [19] System according to claim 18, wherein the program instructions, when executed, are further configured to: to reduce the power threshold of the fuel cell between a maximum power threshold based on the increase in the measured temperature of the fuel cell and a power value of a fifth temperature, if the measured temperature of the fuel cell is in the range of the fifth temperature, which is preset so that it is greater than the third temperature and less than the fourth temperature. [20] System according to claim 18, wherein the program instructions, when executed, are configured to: to reduce the power threshold of the fuel cell between a power value at a fifth temperature and the minimum power threshold when the measured temperature of the fuel cell is greater than the fifth temperature, which is preset so that it is greater than the third temperature and less than the fourth temperature.

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