Apparatus for controlling power of hydrogen fuel cell and operating method thereof

Abstract

A hydrogen fuel cell power control device according to the present invention comprises: a first hydrogen fuel cell assembly formed by connecting a first number of first hydrogen fuel cell modules in series and parallel; a second hydrogen fuel cell assembly formed by connecting a second number of second hydrogen fuel cell modules in series and parallel, connected in series with the first hydrogen fuel cell assembly; and a power control unit that provides an output voltage and an output current, wherein the power control unit is characterized by selectively providing the voltage across the series connection of the first hydrogen fuel cell assembly and the second hydrogen fuel cell assembly as the output voltage or providing the voltage across the second hydrogen fuel cell assembly as the output voltage depending on the output current.

Description

Technology Field

[0001] The present invention relates to a power control device for a hydrogen fuel cell that can be applied to small mobility devices such as drones, and a method of operation thereof. Background Technology

[0002] Hydrogen fuel cells are devices that generate electricity through the chemical reaction between hydrogen and oxygen. Because they produce electrical energy using oxidation-reduction reactions, they offer high energy efficiency. Hydrogen fuel cells can be utilized in various fields, ranging from small-scale mobility to large-scale power generation. In particular, one of the major drawbacks of drones is the limitation of flight time due to battery capacity, but this disadvantage can be significantly overcome by using hydrogen fuel cells.

[0003] Generally, the output of a hydrogen fuel cell exhibits a significant voltage difference depending on the load. Figure 1 shows an example of the current-voltage curve of a hydrogen fuel cell. Referring to Figure 1, it can be seen that the voltage drops sharply with increasing current (load) in the current-voltage (IV) characteristics of the hydrogen fuel cell. For example, in the case of a hydrogen fuel cell with a maximum output of 88 kW, the starting output voltage is 480 V, but at a maximum output of 88 kW, the output voltage drops to approximately 280 V, resulting in a voltage drop of about 200 V. Therefore, hydrogen fuel cells are unsuitable power sources for use in loads that can only receive a constant voltage or a voltage within a certain range.

[0004] Conventionally, to solve these problems, a separate DC-DC converter for constant voltage output is employed in hydrogen fuel cells. Such constant voltage DC-DC converters basically weigh about 0.5 kg per 1 kW. In addition, DC-DC converters generate a large amount of heat, requiring a separate cooling device. The weight of such a cooling device is also more than 10 kg in the case of a 70 kW capacity DC-DC converter.

[0005] As a result, hydrogen fuel cells are applied very restrictively in the aircraft or drone sectors where lightweighting is essential. For example, the output of hydrogen fuel cells applied to existing aircraft or drones is mostly 10 kW or less. In addition, the total operating time of the drone is reduced due to the weight of the DC-DC converter and cooling device required in addition to the hydrogen fuel cell. The problem to be solved

[0006] The technical problem that the present invention aims to solve is to provide a power control device for a hydrogen fuel cell and a method of operation thereof that can maintain the output voltage of the hydrogen fuel cell within a constant voltage range without using a DC-DC converter.

[0007] The problems to be solved by the present invention are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art from the description below. means of solving the problem

[0008] A hydrogen fuel cell power control device according to the present invention for solving the above technical problem comprises: a first hydrogen fuel cell assembly formed by connecting a first number of first hydrogen fuel cell modules in series and parallel; a second hydrogen fuel cell assembly formed by connecting a second number of second hydrogen fuel cell modules in series and parallel, connected in series with the first hydrogen fuel cell assembly; and a power control unit that provides an output voltage and an output current, wherein the power control unit is characterized by selectively providing the voltage across the series connection of the first hydrogen fuel cell assembly and the second hydrogen fuel cell assembly as the output voltage or providing the voltage across the second hydrogen fuel cell assembly as the output voltage depending on the output current.

[0009] The power control unit may provide the voltage across the series connection as the output voltage if the output current is greater than or equal to a predetermined threshold current, and provide the voltage across the second hydrogen fuel cell assembly as the output voltage if the output current is less than a predetermined threshold current.

[0010] The first hydrogen fuel cell assembly includes one end and the other end, and the second hydrogen fuel cell assembly includes one end and the other end, and the other end of the first hydrogen fuel cell assembly and one end of the second hydrogen fuel cell assembly are connected to each other, and the power control unit may provide the voltage between one end of the first hydrogen fuel cell assembly and the other end of the second hydrogen fuel cell assembly as the output voltage when providing the voltage across the two ends of the series connection as the output voltage, and may provide the voltage between one end and the other end of the second hydrogen fuel cell assembly as the output voltage when providing the voltage across the two ends of the second hydrogen fuel cell assembly as the output voltage.

[0011] The power control unit provides first, second, third, fourth, and fifth terminals, the first terminal is connected to one end of the first hydrogen fuel cell assembly, the second terminal is connected to the other end of the first hydrogen fuel cell assembly and one end of the second hydrogen fuel cell assembly, the third terminal is connected to the other end of the second hydrogen fuel cell assembly, and the third terminal and the fifth terminal are connected to each other, and the fourth and fifth terminals of the power control unit provide the output voltage and the output current, and the power control unit may connect the first terminal and the fourth terminal when providing the voltage across the two ends of the series connection as the output voltage, and connect the second terminal and the fourth terminal when providing the voltage across the two ends of the second hydrogen fuel cell assembly as the output voltage.

[0012] The power control unit comprises: a first relay provided between the first terminal and the fourth terminal; a second relay provided between the second terminal and the fourth terminal; and a relay control unit that controls the on / off of the first relay and the second relay according to the output current, wherein the relay control unit may turn on the first relay and turn off the second relay to provide the voltage across the series connection as the output voltage, and turn off the first relay and turn on the second relay to provide the voltage across the second hydrogen fuel cell assembly as the output voltage.

[0013] The power control unit further includes a first current / voltage sensor that senses the current and voltage of the first terminal; and a second current / voltage sensor that senses the current and voltage of the second terminal, and the relay control unit can control the on / off of the first relay and the second relay according to the sensed current and sensed voltage of the first current / voltage sensor or the sensed current and sensed voltage of the second current / voltage sensor.

[0014] The relay control unit can turn on the first relay and turn off the second relay when the first relay is in the off state and the second relay is in the on state, and the sensing current of the second current / voltage sensor is greater than or equal to a predetermined threshold current and the sensing voltage of the second current / voltage sensor is greater than or equal to a predetermined threshold voltage.

[0015] The relay control unit can output an overcurrent warning if the sensing current of the second current / voltage sensor is greater than or equal to the predetermined threshold current and the sensing voltage of the second current / voltage sensor is less than the predetermined threshold voltage.

[0016] The relay control unit can maintain the off state of the first relay and the on state of the second relay when the first relay is in the off state and the second relay is in the on state, and the sensing current of the second current / voltage sensor is less than a predetermined threshold current and the sensing voltage of the second current / voltage sensor is less than a predetermined threshold voltage.

[0017] The relay control unit can output an overvoltage warning if the sensing current of the second current / voltage sensor is less than the predetermined threshold current and the sensing voltage of the second current / voltage sensor is greater than or equal to the predetermined threshold voltage.

[0018] The relay control unit can maintain the ON state of the first relay and the OFF state of the second relay when the first relay is in the ON state and the second relay is in the OFF state, if the sensing current of the first current / voltage sensor is greater than or equal to a predetermined threshold current and the sensing voltage of the first current / voltage sensor is greater than or equal to a predetermined threshold voltage.

[0019] The relay control unit can output an overcurrent warning if the sensing current of the first current / voltage sensor is greater than or equal to the predetermined threshold current and the sensing voltage of the first current / voltage sensor is less than the predetermined threshold voltage.

[0020] The relay control unit can turn off the first relay and turn on the second relay when the first relay is in the ON state and the second relay is in the OFF state, and the sensing current of the first current / voltage sensor is less than a predetermined threshold current and the sensing voltage of the second current / voltage sensor is less than a predetermined threshold voltage.

[0021] The relay control unit can output an overvoltage warning if the sensing current of the first current / voltage sensor is less than the predetermined threshold current and the sensing voltage of the first current / voltage sensor is greater than or equal to the predetermined threshold voltage.

[0022] In a method of operation of a hydrogen fuel cell power control device according to the present invention for solving the above technical problem, the hydrogen fuel cell power control device comprises: a first hydrogen fuel cell assembly formed by connecting a first number of first hydrogen fuel cell modules in series and parallel; a second hydrogen fuel cell assembly formed by connecting a second number of second hydrogen fuel cell modules in series and parallel and connecting the first hydrogen fuel cell assembly in series; and a power control unit that provides an output voltage and an output current. The method of operation is characterized by comprising: a step of providing the voltage across the series connection of the first hydrogen fuel cell assembly and the second hydrogen fuel cell assembly as the output voltage if the output current is greater than or equal to a predetermined threshold current; and a step of providing the voltage across the second hydrogen fuel cell assembly as the output voltage if the output current is less than the predetermined threshold current.

[0023] The first hydrogen fuel cell assembly comprises one end and the other end, and the second hydrogen fuel cell assembly comprises one end and the other end, and the other end of the first hydrogen fuel cell assembly and one end of the second hydrogen fuel cell assembly are connected to each other, and the step of providing the voltage across the two ends of the series connection as the output voltage may be provided as the output voltage, wherein the voltage between one end of the first hydrogen fuel cell assembly and the other end of the second hydrogen fuel cell assembly is provided as the output voltage, and the step of providing the voltage across the two ends of the second hydrogen fuel cell assembly as the output voltage may be provided as the output voltage, wherein the voltage between one end and the other end of the second hydrogen fuel cell assembly is provided as the output voltage.

[0024] The power control unit provides first, second, third, fourth, and fifth terminals, the first terminal is connected to one end of the first hydrogen fuel cell assembly, the second terminal is connected to the other end of the first hydrogen fuel cell assembly and one end of the second hydrogen fuel cell assembly, the third terminal is connected to the other end of the second hydrogen fuel cell assembly, and the third terminal and the fifth terminal are connected to each other, the fourth and fifth terminals of the power control unit provide the output voltage and the output current, and the step of providing the voltage across the two ends of the series connection as the output voltage may be to connect the first terminal and the fourth terminal, and the step of providing the voltage across the two ends of the second hydrogen fuel cell assembly as the output voltage may be to connect the second terminal and the fourth terminal. Effects of the invention

[0025] According to the present invention described above, the output voltage of a hydrogen fuel cell can be maintained within a constant voltage range without using a DC-DC converter.

[0026] Therefore, the present invention achieves lightweighting of hydrogen fuel cells, enabling effective utilization in small mobility fields such as drones.

[0027] The effects of the present invention are not limited to those mentioned above, and other unmentioned effects will be clearly understood by those skilled in the art from the description below. Brief explanation of the drawing

[0028] Figure 1 shows an example of a current-voltage curve of a hydrogen fuel cell. FIG. 2 shows the configuration of a hydrogen fuel cell power control device according to one embodiment of the present invention. FIG. 3 shows the operation of a high-voltage mode of a hydrogen fuel cell power control device according to one embodiment of the present invention. FIG. 4 shows the operation of a low-voltage mode of a hydrogen fuel cell power control device according to one embodiment of the present invention. FIG. 5 shows the configuration of a power control unit (300) according to one embodiment of the present invention. FIG. 6 shows a specific operation flowchart of a power control unit (300) according to one embodiment of the present invention. Figure 7 shows the current-voltage curve of a conventional hydrogen fuel cell and the current-voltage curve according to the present invention. Specific details for implementing the invention

[0029] Preferred embodiments of the present invention will be described in detail below with reference to the drawings. In the following description and the attached drawings, substantially identical components are denoted by the same reference numerals to avoid redundant description. Furthermore, in describing the present invention, if it is determined that a detailed description of related known functions or configurations could unnecessarily obscure the essence of the invention, such detailed description will be omitted.

[0030] FIG. 2 shows the configuration of a hydrogen fuel cell power control device according to one embodiment of the present invention.

[0031] Referring to FIG. 2, a hydrogen fuel cell power control device according to an embodiment of the present invention includes a first hydrogen fuel cell assembly (100), a second hydrogen fuel cell assembly (200), and a power control unit (300).

[0032] The first hydrogen fuel cell assembly (100) is formed by connecting a first number of first hydrogen fuel cell modules (110) in series and parallel. For example, the first hydrogen fuel cell module (110) may consist of 54 hydrogen fuel cell cells, and the first hydrogen fuel cell assembly (100) may consist of a series connection of 2 first hydrogen fuel cell modules (110) and a parallel connection of 6 of the corresponding series connections, thereby being composed of a total of 12 first hydrogen fuel cell modules (110). Additionally, the first hydrogen fuel cell assembly (100) may include one end (101) and the other end (102).

[0033] The second hydrogen fuel cell assembly (200) is formed by connecting a second number of second hydrogen fuel cell modules (210) in series and parallel. For example, the second hydrogen fuel cell module (210) may consist of 72 hydrogen fuel cell cells, and the second hydrogen fuel cell assembly (200) may consist of a series connection of 5 second hydrogen fuel cell modules (210) and a parallel connection of 6 of the corresponding series connections, thereby being composed of a total of 30 second hydrogen fuel cell modules (210). Additionally, the second hydrogen fuel cell assembly (200) may include one end (201) and the other end (202).

[0034] The first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) are connected in series. For example, the other end (102) of the first hydrogen fuel cell assembly (100) and the first end (201) of the second hydrogen fuel cell assembly (200) can be connected to each other.

[0035] The power control unit (300) provides an output voltage and an output current from the first hydrogen fuel cell assembly (100) and / or the second hydrogen fuel cell assembly (200). Depending on the output current, the power control unit (300) may selectively provide the voltage across the series connection of the first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) as the output voltage, or provide the voltage across the second hydrogen fuel cell assembly (200) as the output voltage, excluding the first hydrogen fuel cell assembly (100). Specifically, the power control unit (300) can operate in a high-voltage mode when the output current is greater than or equal to a predetermined threshold current (e.g., 220A) to provide the voltage at both ends of the series connection of the first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) as the output voltage, and can operate in a low-voltage mode when the output current is less than the predetermined threshold current to provide the voltage at both ends of the second hydrogen fuel cell assembly (200) as the output voltage.

[0036] The power control unit (300) can provide the voltage between one end (101) of the first hydrogen fuel cell assembly (100) and the other end (202) of the second hydrogen fuel cell assembly (200) as the output voltage when providing the voltage between the two ends of the series connection of the first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) as the output voltage (high voltage mode). The power control unit (300) can provide the voltage between one end (201) and the other end (202) of the second hydrogen fuel cell assembly (200) as the output voltage when providing the voltage between the two ends of the second hydrogen fuel cell assembly (200) as the output voltage (low voltage mode).

[0037] FIG. 3 shows the operation of a high-voltage mode of a hydrogen fuel cell power control device according to one embodiment of the present invention, and FIG. 4 shows the operation of a low-voltage mode of a hydrogen fuel cell power control device according to one embodiment of the present invention.

[0038] The power control unit (300) may provide first, second, third, fourth, and fifth terminals (301, 302, 303, 304, and 305).

[0039] The first terminal (301) can be connected to one end (101) of the first hydrogen fuel cell assembly (100). The second terminal (302) can be connected to the other end (102) of the first hydrogen fuel cell assembly (100) and one end (201) of the second hydrogen fuel cell assembly (200). The third terminal (303) can be connected to the other end (202) of the second hydrogen fuel cell assembly (200). The third terminal (303) and the fifth terminal (305) can be connected to each other. And output voltage and output current can be provided through the fourth and fifth terminals (304, 305). According to an embodiment, the third terminal (303) and the fifth terminal (305) may be composed of a single terminal.

[0040] Referring to FIG. 3, the power control unit (300) can connect the first terminal (301) and the fourth terminal (304) when providing the voltage across the series connection of the first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) as the output voltage (high voltage mode). Thus, in high voltage mode, the voltage corresponding to the series connection of seven hydrogen fuel cell modules (110, 210) and the parallel connection of six of the corresponding series connections can be provided as the output voltage. As a result, in high voltage mode, the output voltage can be 337.0V based on an output current of 220A.

[0041] Referring to FIG. 4, the power control unit (300) can connect the second terminal (302) and the fourth terminal (304) when providing the voltage across the second hydrogen fuel cell assembly (200) as an output voltage (low voltage mode). Thus, in low voltage mode, the voltage resulting from the series connection of five hydrogen fuel cell modules (210) and the parallel connection of six corresponding series connections can be provided as an output voltage. As a result, in low voltage mode, the output voltage can be 259.2V based on an output current of 220A.

[0042] FIG. 5 shows the configuration of a power control unit (300) according to one embodiment of the present invention.

[0043] Referring to FIG. 5, the power control unit (300) may include a first diode (D1), a first current / voltage sensor (310), a first relay (330), a second diode (D2), a second current / voltage sensor (320), a second relay (340), a relay control unit (350), and a battery (360) for back EMF prevention. The first diode (D1), the first current / voltage sensor (310), and the first relay (330) may be provided between the first terminal (301) and the fourth terminal (304). The second diode (D2), the second current / voltage sensor (320), and the second relay (340) may be provided between the second terminal (301) and the fourth terminal (304).

[0044] The first relay (330) connects or disconnects the first terminal (301) and the fourth terminal (304) of the power control unit (300). The second relay (340) connects or disconnects the second terminal (302) and the fourth terminal (304) of the power control unit (300). The first relay (330) and the second relay (340) can operate complementarily. That is, when the first relay (330) is on, the second relay (340) is off, and when the first relay (330) is off, the second relay (340) can be turned on.

[0045] The first current / voltage sensor (310) senses the current and voltage output from one end (101) of the first hydrogen fuel cell assembly (100). That is, the first current / voltage sensor (310) senses the current and voltage of the first terminal (301) of the power control unit (300). When the first relay (330) is on and the second relay (340) is off, the sensed current and sensed voltage of the first current / voltage sensor (310) become the output current and output voltage of the power control unit (300), respectively.

[0046] The second current / voltage sensor (320) senses the current and voltage output from one end (201) of the second hydrogen fuel cell assembly (200). That is, the second current / voltage sensor (320) senses the current and voltage of the second terminal (302) of the power control unit (300). When the second relay (340) is on and the first relay (330) is off, the sensed current and sensed voltage of the second current / voltage sensor (320) become the output current and output voltage of the power control unit (300), respectively.

[0047] The first diode (D1) prevents back electromotive force from being introduced into the first hydrogen fuel cell assembly (100). The second diode (D2) prevents back electromotive force from being input into the second hydrogen fuel cell assembly (200).

[0048] The relay control unit (350) controls the on / off of the first relay (330) and the on / off of the second relay (340) according to the output current of the power control unit (300), that is, the sensing current of the first current / voltage sensor (310) or the sensing current of the second current / voltage sensor (320).

[0049] Specifically, if the output current of the power control unit (300) is greater than or equal to a predetermined threshold current, the relay control unit (350) can turn on the first relay (330) and turn off the second relay (340) in order to provide the voltage across the series connection of the first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) as the output voltage. Conversely, if the output current of the power control unit (300) is less than a predetermined threshold current, the relay control unit (350) can turn off the first relay (330) and turn on the second relay (340) in order to provide the voltage across the second hydrogen fuel cell assembly (200) as the output voltage.

[0050] A back EMF prevention battery (360) may be provided between the fourth terminal (304) and the fifth terminal (305). The back EMF prevention battery (360) serves to absorb power input in reverse from the output terminal, such as regenerative or surplus power.

[0051] FIG. 6 shows a specific operation flowchart of a power control unit (300) according to one embodiment of the present invention.

[0052] In step 601, the hydrogen fuel cell is turned on. At this time, the first relay (330) may be in the ON state and the second relay (340) may be in the OFF state, or conversely, the first relay (330) may be in the OFF state and the second relay (340) may be in the ON state. By default, the first relay (330) may be in the OFF state and the second relay (340) may be in the ON state.

[0053] In step 610, the relay control unit (350) determines whether the sensing current of the second current / voltage sensor (320) is greater than 0A. If the sensing current of the second current / voltage sensor (320) is greater than 0A, it can be seen that the first relay (330) is in the off state and the second relay (340) is in the on state.

[0054] If the sensing current of the second current / voltage sensor (320) is greater than 0A (Y in step 610), in step 611, the relay control unit (350) determines whether the sensing current of the second current / voltage sensor (320) is greater than or equal to a predetermined threshold current (e.g., 220A).

[0055] If the sensing current of the second current / voltage sensor (320) is greater than or equal to a predetermined threshold current (Y in step 611), in step 612, the relay control unit (350) determines whether the sensing voltage of the second current / voltage sensor (320) is greater than or equal to a predetermined threshold voltage (e.g., 259.2V).

[0056] If the sensing voltage of the second current / voltage sensor (320) is greater than or equal to a predetermined threshold voltage (Y in step 612), in step 613, the relay control unit (350) turns on the first relay (330) and turns off the second relay (340). Accordingly, the voltage across the series connection of the first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) is provided as an output voltage.

[0057] If the sensing voltage of the second current / voltage sensor (320) is less than a predetermined threshold voltage (N in step 612), the relay control unit (350) may output an overcurrent warning in step 614. In this case, to cut off the power output, the relay control unit (350) may turn off both the first relay (330) and the second relay (340).

[0058] If the sensing current of the second current / voltage sensor (320) is less than a predetermined threshold current (N in step 611), in step 615, the relay control unit (350) determines whether the sensing voltage of the second current / voltage sensor (320) is less than a predetermined threshold voltage (e.g., 259.2V).

[0059] If the sensing voltage of the second current / voltage sensor (320) is less than a predetermined threshold voltage (Y in step 615), in step 616, the relay control unit (350) maintains the off state of the first relay (330) and the on state of the second relay (340). Thus, the voltage across the second hydrogen fuel cell assembly (200) is provided as an output voltage.

[0060] If the sensing voltage of the second current / voltage sensor (320) is greater than or equal to a predetermined threshold voltage (N in step 615), the relay control unit (350) may output an overvoltage warning in step 617. In this case, to cut off the power output, the relay control unit (350) may turn off both the first relay (330) and the second relay (340).

[0061] If the sensing current of the second current / voltage sensor (320) is not greater than 0A (N in step 610), in step 630, the relay control unit (350) determines whether the sensing current of the first current / voltage sensor (310) is greater than 0A. If the sensing current of the first current / voltage sensor (310) is greater than 0A, it can be seen that the first relay (330) is in the ON state and the second relay (340) is in the OFF state.

[0062] If the sensing current of the first current / voltage sensor (310) is greater than 0A (Y in step 630), in step 631, the relay control unit (350) determines whether the sensing current of the first current / voltage sensor (310) is greater than or equal to a predetermined threshold current (e.g., 220A).

[0063] If the sensing current of the first current / voltage sensor (310) is greater than or equal to a predetermined threshold current (Y in step 631), in step 632, the relay control unit (350) determines whether the sensing voltage of the first current / voltage sensor (310) is greater than or equal to a predetermined threshold voltage (e.g., 259.2V).

[0064] If the sensing voltage of the first current / voltage sensor (310) is greater than or equal to a predetermined threshold voltage (Y in step 632), in step 633, the relay control unit (350) maintains the ON state of the first relay (330) and the OFF state of the second relay (340). Accordingly, the voltage across the two ends of the series connection of the first hydrogen fuel cell assembly (100) and the second hydrogen fuel cell assembly (200) is provided as an output voltage.

[0065] If the sensing voltage of the first current / voltage sensor (310) is less than a predetermined threshold voltage (N in step 632), the relay control unit (350) may output an overcurrent warning in step 634. In this case, to cut off the power output, the relay control unit (350) may turn off both the first relay (330) and the second relay (340).

[0066] If the sensing current of the first current / voltage sensor (310) is less than a predetermined threshold current (N in step 631), in step 635, the relay control unit (350) determines whether the sensing voltage of the first current / voltage sensor (310) is less than a predetermined threshold voltage (e.g., 259.2V).

[0067] If the sensing voltage of the first current / voltage sensor (310) is less than a predetermined threshold voltage (Y in step 635), in step 636, the relay control unit (350) turns off the first relay (330) and turns on the second relay (340). Accordingly, the voltage across the second hydrogen fuel cell assembly (200) is provided as an output voltage.

[0068] If the sensing voltage of the first current / voltage sensor (310) is greater than or equal to a predetermined threshold voltage (N in step 635), the relay control unit (350) may output an overvoltage warning in step 637. In this case, to cut off the power output, the relay control unit (350) may turn off both the first relay (330) and the second relay (340).

[0069] FIG. 7 shows the current-voltage curve of a conventional hydrogen fuel cell and the current-voltage curve according to the present invention. Referring to FIG. 7, it can be seen that the current-voltage characteristics of the conventional hydrogen fuel cell have a maximum output voltage difference of about 200V (a), whereas according to an embodiment of the present invention, the maximum output voltage difference is reduced to about 140V (b).

[0070] The following table shows a comparison between a conventional hydrogen fuel cell and an embodiment of the present invention.

[0071] existing The present invention Improvement effect DC-DC converter Required (40kg) Unnecessary (0kg) 40kg saved cooling device Needed (10kg) Unnecessary (0kg) 10kg saved Maximum output voltage difference 220V 140V 30% decrease

[0072] While conventional hydrogen fuel cells require a DC-DC converter for constant voltage output and a cooling device for cooling, according to the present invention, neither the DC-DC converter nor the cooling device is required, making weight reduction possible.

[0073] In addition, according to the present invention, the phenomenon of high voltage drop can be mitigated even when the output is increased. For example, in the conventional method, in the case of a hydrogen fuel cell with a maximum output of 88kW, if a DC-DC converter is not applied, the starting output voltage is 480V, but at a maximum output of 88kW, the output voltage drops to about 280V, resulting in a maximum output voltage difference of about 200V. However, according to the present invention, the maximum output voltage difference is reduced to 140V, which has the effect of increasing output voltage stability by more than 30%.

[0074] Combinations of each block of the block diagram attached to the present invention and each step of the flowchart may be performed by computer program instructions. Since these computer program instructions may be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions performed through the processor of the computer or other programmable data processing equipment create means for performing the functions described in each block of the block diagram or each step of the flowchart. Since these computer program instructions may also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific manner, the instructions stored in computer-available or computer-readable memory may also produce a manufactured item containing instruction means for performing the function described in each block of the block diagram or each step of the flowchart. Since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that execute a computer or other programmable data processing equipment by performing a series of operation steps on the computer or other programmable data processing equipment to create a process executed by the computer can also provide steps for executing the functions described in each block of the block diagram and each step of the flowchart.

[0075] Additionally, each block or each step may represent a module, segment, or part of code containing one or more executable instructions for executing a specified logical function(s). Also, it should be noted that in some alternative embodiments, the functions mentioned in the blocks or steps may occur out of order. For example, two blocks or steps described in succession may actually be performed substantially simultaneously, or the blocks or steps may sometimes be performed in reverse order according to the corresponding function.

[0076] The foregoing description is merely an illustrative explanation of the technical concept of the present invention, and those skilled in the art to which the present invention pertains will be able to make various modifications and variations within the scope of the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are intended to explain, not limit, the technical concept of the present invention, and the scope of the technical concept of the present invention is not limited by these embodiments. The scope of protection of the present invention shall be interpreted by the claims below, and all technical concepts within an equivalent scope shall be interpreted as being included within the scope of rights of the present invention.

Claims

Claim 1 A first hydrogen fuel cell assembly formed by connecting a first number of first hydrogen fuel cell modules in series and parallel; a second hydrogen fuel cell assembly connected in series with the first hydrogen fuel cell assembly and formed by connecting a second number of second hydrogen fuel cell modules in series and parallel;The system includes a power control unit that provides an output voltage and an output current, wherein the power control unit provides the voltage across the series connection of the first hydrogen fuel cell assembly and the second hydrogen fuel cell assembly as the output voltage if the output current is greater than or equal to a predetermined threshold current, and provides the voltage across the second hydrogen fuel cell assembly as the output voltage if the output current is less than the predetermined threshold current, wherein the first hydrogen fuel cell assembly includes one end and the other end, and the second hydrogen fuel cell assembly includes one end and the other end, and the other end of the first hydrogen fuel cell assembly and one end of the second hydrogen fuel cell assembly are connected to each other, and wherein the power control unit, when providing the voltage across the series connection as the output voltage, provides the voltage between one end of the first hydrogen fuel cell assembly and the other end of the second hydrogen fuel cell assembly as the output voltage, and when providing the voltage across the second hydrogen fuel cell assembly as the output voltage, the one end of the second hydrogen fuel cell assembly and The voltage between the other ends is provided as the output voltage, and the power control unit provides first, second, third, fourth, and fifth terminals, the first terminal is connected to one end of the first hydrogen fuel cell assembly, the second terminal is connected to the other end of the first hydrogen fuel cell assembly and one end of the second hydrogen fuel cell assembly, the third terminal is connected to the other end of the second hydrogen fuel cell assembly, and the third terminal and the fifth terminal are connected to each other, and the fourth and fifth terminals of the power control unit provide the output voltage and the output current, and the power control unit connects the first terminal and the fourth terminal when providing the voltage across the two ends of the series connection as the output voltage, and connects the second terminal and the fourth terminal when providing the voltage across the two ends of the second hydrogen fuel cell assembly as the output voltage, and the power control unit provides a first relay provided between the first terminal and the fourth terminal; A second relay provided between the second terminal and the fourth terminal;and includes a relay control unit that controls the on / off of the first relay and the second relay according to the output current, wherein the relay control unit turns on the first relay and turns off the second relay to provide the voltage across the terminals of the series connection as the output voltage, and turns off the first relay and turns on the second relay to provide the voltage across the terminals of the second hydrogen fuel cell assembly as the output voltage, and the power control unit includes a first current / voltage sensor that senses the current and voltage of the first terminal;and further includes a second current / voltage sensor for sensing the current and voltage of the second terminal, and the relay control unit controls the on / off of the first relay and the second relay according to the sensing current and sensing voltage of the first current / voltage sensor or the sensing current and sensing voltage of the second current / voltage sensor, and the relay control unit, when the first relay is in the off state and the second relay is in the on state, if the sensing current of the second current / voltage sensor is greater than or equal to a predetermined threshold current and the sensing voltage of the second current / voltage sensor is greater than or equal to a predetermined threshold voltage, turns on the first relay and turns off the second relay so that the voltage across the terminals of the series connection is provided as the output voltage, and when the first relay is in the off state and the second relay is in the on state, if the sensing current of the second current / voltage sensor is less than a predetermined threshold current and the sensing voltage of the second current / voltage sensor is less than a predetermined threshold voltage, maintains the off state of the first relay and the on state of the second relay so that the second A hydrogen fuel cell power control device characterized by providing the voltage across the terminals of a hydrogen fuel cell assembly as the output voltage, wherein when the first relay is in the ON state and the second relay is in the OFF state, if the sensing current of the first current / voltage sensor is greater than or equal to a predetermined threshold current and the sensing voltage of the first current / voltage sensor is greater than or equal to a predetermined threshold voltage, the ON state of the first relay and the OFF state of the second relay are maintained so that the voltage across the terminals of the series connection is provided as the output voltage, and when the first relay is in the ON state and the second relay is in the OFF state, if the sensing current of the first current / voltage sensor is less than a predetermined threshold current and the sensing voltage of the second current / voltage sensor is less than a predetermined threshold voltage, the first relay is turned OFF and the second relay is turned ON so that the voltage across the terminals of the second hydrogen fuel cell assembly is provided as the output voltage. Claim 2 delete Claim 3 delete Claim 4 delete Claim 5 delete Claim 6 delete Claim 7 delete Claim 8 A hydrogen fuel cell power control device according to claim 1, wherein the relay control unit outputs an overcurrent warning when the sensing current of the second current / voltage sensor is greater than or equal to the predetermined threshold current and the sensing voltage of the second current / voltage sensor is less than the predetermined threshold voltage. Claim 9 delete Claim 10 A hydrogen fuel cell power control device according to claim 1, wherein the relay control unit outputs an overvoltage warning when the sensing current of the second current / voltage sensor is less than the predetermined threshold current and the sensing voltage of the second current / voltage sensor is greater than or equal to the predetermined threshold voltage. Claim 11 delete Claim 12 A hydrogen fuel cell power control device according to claim 1, wherein the relay control unit outputs an overcurrent warning when the sensing current of the first current / voltage sensor is greater than or equal to the predetermined threshold current and the sensing voltage of the first current / voltage sensor is less than the predetermined threshold voltage. Claim 13 delete Claim 14 A hydrogen fuel cell power control device according to claim 1, wherein the relay control unit outputs an overvoltage warning when the sensing current of the first current / voltage sensor is less than the predetermined threshold current and the sensing voltage of the first current / voltage sensor is greater than or equal to the predetermined threshold voltage. Claim 15 delete Claim 16 delete Claim 17 delete

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