A multi-cascade structured battery stack and fuel cell system

Abstract

The present invention discloses a multi-cascade structure of an electric stack and a fuel cell system, wherein the electric stack includes a multi-stage battery array connected in series, a first fuel flow path and a second fuel flow path, each battery array includes a plurality of parallel single cells, each battery array is connected through the first fuel flow path, and the single cells in the same battery array are connected through the second fuel flow path, wherein the number of single cells in each battery array and the array fuel utilization rate corresponding to each battery array meet the first single cell number constraint condition, and the number of single cells in the front and rear battery arrays and the battery fuel utilization rate corresponding to each single cell in the previous battery array meet the second single cell number constraint condition, so that the amount of hydrogen in the fuel passing into each single cell per unit time is equal. The present invention can realize the recycling of fuel, improve fuel utilization and power generation efficiency, and can reduce the risk of over-utilization of single cells and electric stacks, and can be widely used in the field of fuel cells.

Description

Technical Field

[0001] The present application relates to the field of fuel cells, and in particular to a fuel cell stack and a fuel cell system with a multi-cascade structure. Background Art

[0002] A fuel cell is an electrochemical device that can directly convert chemical energy stored in fuel and oxidant into electrical energy. Fuel cells are usually stacked as single cells; one or more stacks and other modules such as gas management modules, water treatment modules, power management modules, and main control modules constitute a fuel cell system.

[0003] In order to improve the power generation power, power generation efficiency and fuel utilization rate of fuel cell systems and stacks, multiple stacks or multiple single cells are usually designed in series and parallel. However, in the current design of fuel cell systems and stacks, there is often a risk of imbalance in the ratio of the number of stacks and single cells, resulting in a decrease in the overall fuel utilization rate of the fuel cell system and stack. Summary of the invention

[0004] In order to solve the above technical problems, the purpose of the present invention is to provide a multi-cascade structured fuel cell stack and fuel cell system with high fuel utilization.

[0005] To achieve the above-mentioned purpose, one aspect of an embodiment of the present application proposes a multi-cascade structured battery stack, comprising a multi-stage battery array connected in series, a first fuel flow path and a second fuel flow path, wherein each stage of the battery array comprises a plurality of single cells connected in parallel, the battery arrays at each stage are connected through the first fuel flow path, and the single cells in the battery array at the same stage are connected through the second fuel flow path, wherein the number of single cells in the battery arrays at each stage and the array fuel utilization rate corresponding to the battery arrays at each stage satisfy a first single cell number constraint, and the number of single cells in the battery arrays of the previous and subsequent stages and the battery fuel utilization rate corresponding to each single cell in the battery array of the previous stage satisfy a second single cell number constraint, so that the amount of hydrogen of fuel passed into each single cell per unit time is equal when the battery stack is operating stably.

[0006] In some embodiments, the number of single batteries in each level of the battery array and the array fuel utilization rate corresponding to each level of the battery array satisfy the first single battery number constraint condition, and the first single battery number constraint condition is:

[0007]

[0008] Among them, N x Indicates C x N1 represents the number of single batteries in the battery array of level C1, N2 represents the number of single batteries in the battery array of level C1, i Indicates Ci The array fuel utilization rate corresponding to the battery array, i and x are both positive integers and i∈[1, x-1].

[0009] In some embodiments, the number of cells in the battery arrays of the previous and next stages and the battery fuel utilization rate corresponding to each cell in the battery array of the previous stage satisfy the second cell number constraint condition, and the second cell number constraint condition is:

[0010]

[0011] Among them, N x Indicates C x The number of cells in the battery array, N x-1 Indicates C x-1 The number of cells in the battery array, γ i Indicates C x-1 The battery fuel utilization rate corresponding to the ith battery in the battery array, i and x are both positive integers and i∈[1, N x-1 ].

[0012] In some embodiments, the stack fuel utilization rate corresponding to the stack and the array fuel utilization rate corresponding to each level of the battery array satisfy the stack fuel utilization rate constraint condition, and the stack fuel utilization rate constraint condition is:

[0013]

[0014] Among them, η 堆 represents the fuel utilization rate of the fuel cell, N i Indicates C i The number of cells in the battery array, n i Indicates C i The array fuel utilization rate corresponding to the battery array, i and x are both positive integers and i∈[1,x].

[0015] In some embodiments, the fuel utilization rate of the fuel cell stack satisfies 60%≤η 堆 ≤99% or 70%≤η 堆 ≤95%, the array fuel utilization rate corresponding to each level of the battery array satisfies 30%≤η x ≤75% or 50%≤η x ≤75%, where η x Indicates C x The array fuel utilization rate corresponding to the battery array, x is a positive integer.

[0016] In some embodiments, the number of single batteries in each level of the battery array satisfies a third single battery number constraint condition, and the third single battery number constraint condition is:

[0017] When the battery stack includes a first-level battery array and a second-level battery array connected in series, the number of single batteries in the first-level battery array and the number of single batteries in the second-level battery array satisfy N1:N2 is one of 2:1, 3:1, 42:13, 39:12 or 4:1, wherein N1 represents the number of single batteries in the first-level battery array, and N2 represents the number of single batteries in the second-level battery array;

[0018] When the battery stack includes a first-level battery array, a second-level battery array and a third-level battery array connected in series, the number of single cells in the first-level battery array, the number of single cells in the second-level battery array and the number of single cells in the third-level battery array satisfy N1:N2:N3, which is one of 9:3:1, 39:12:4 or 42:13:4, wherein N1 represents the number of single cells in the first-level battery array, N2 represents the number of single cells in the second-level battery array, and N3 represents the number of single cells in the third-level battery array.

[0019] To achieve the above-mentioned purpose, another aspect of an embodiment of the present application proposes a fuel cell system with a multi-cascade structure, including multiple stages of series-connected fuel cell groups, a third fuel flow path, and a fourth fuel flow path, wherein each stage of the fuel cell groups includes multiple parallel fuel cell stacks, the fuel cell stack groups at each stage are connected through the third fuel flow path, and the fuel cell stacks in the same stage of the fuel cell groups are connected through the fourth fuel flow path, wherein the number of fuel cell stacks in each stage of the fuel cell stack groups and the fuel utilization rate of the fuel cell stack groups corresponding to each stage of the fuel cell stack groups satisfy a first fuel cell stack number constraint condition, and the number of fuel cell stacks in the previous and next stage fuel cell stack groups and the fuel utilization rate of the fuel cell stacks corresponding to each fuel cell stack in the previous stage of the fuel cell stack group satisfy a second fuel cell stack number constraint condition, so that the amount of hydrogen fuel passed into each fuel cell stack per unit time is equal when the fuel cell system is operating stably.

[0020] In some embodiments, the number of battery stacks in each level of the battery stack group and the fuel utilization rate of the battery stack group corresponding to each level of the battery stack group satisfy the first battery stack number constraint condition, and the first battery stack number constraint condition is:

[0021]

[0022] Among them, M y Indicates D y M1 represents the number of stacks in the stack group of level D1, μ j Indicates D jThe fuel utilization rate of the fuel cell group corresponding to the fuel cell group, j and y are both positive integers and j∈[1, y-1].

[0023] In some embodiments, the number of battery stacks in the battery stack groups of the previous and next stages and the battery stack fuel utilization rate corresponding to each battery stack in the battery stack group of the previous stage meet the second battery stack number constraint condition, and the second battery stack number constraint condition is:

[0024]

[0025] Among them, M y Indicates D y The number of stacks in the stack group of the level, M y-1 Indicates D y-1 The number of stacks in the stack group of the level, δ j Indicates D y-1 The fuel utilization rate of the fuel cell corresponding to the jth fuel cell in the fuel cell group, j and y are both positive integers and j∈[1, M y-1 ].

[0026] In some embodiments, the system fuel utilization rate corresponding to the fuel cell system and the fuel utilization rate of the fuel stack group corresponding to each level of the fuel stack group satisfy the system fuel utilization rate constraint condition, and the system fuel utilization rate constraint condition is;

[0027]

[0028] Among them, μ 总 represents the fuel utilization rate of the system, M y Indicates D y The number of stacks in the stack group of the level, μ j Indicates D j The fuel utilization rate of the fuel stack group corresponding to the level of the fuel stack group, j and y are positive integers and j∈[1,y].

[0029] In some embodiments, the system fuel utilization rate satisfies 60%≤μ 总 ≤99% or 70%≤μ 总 ≤95%, the fuel utilization rate of the stack group corresponding to each level of the stack group meets 30%≤μ y ≤75% or 50%≤μ y ≤75%, where μ y Indicates D y The fuel utilization rate of the fuel stack group corresponding to the level of the fuel stack group, y is a positive integer.

[0030] In some embodiments, the number of battery stacks in each level of the battery stack group satisfies a third battery stack number constraint condition, and the third battery stack number constraint condition is:

[0031] When the fuel cell system comprises a first-stage stack group and a second-stage stack group connected in series, the number of stacks in the first-stage stack group and the number of stacks in the second-stage stack group satisfy M1:M2, which is one of 2:1, 3:1, 42:13, 39:12 or 4:1, wherein M1 represents the number of stacks in the first-stage stack group, and M2 represents the number of stacks in the second-stage stack group;

[0032] When the fuel cell system includes a first-stage fuel cell group, a second-stage fuel cell group and a third-stage fuel cell group connected in series, the number of fuel cells in the first-stage fuel cell group, the number of fuel cells in the second-stage fuel cell group and the number of fuel cells in the third-stage fuel cell group satisfy M1:M2:M3, which is one of 9:3:1, 39:12:4 or 42:13:4, wherein M1 represents the number of fuel cells in the fuel cell group, M2 represents the number of fuel cells in the second-stage fuel cell group, and M3 represents the number of fuel cells in the third-stage fuel cell group.

[0033] The beneficial effects of the present invention are as follows: a multi-stage cascade structure fuel cell stack provided by the present invention forms a fuel cell array by connecting the second fuel flow paths of multiple single cells in parallel, and connects the first fuel flow paths of the multi-stage battery array in series to form a fuel cell stack, so that the fuel exhaust gas discharged from the previous stage flows into the next stage for reaction, thereby realizing the recycling of fuel and improving fuel utilization and power generation efficiency; in addition, the number of single cells is limited by the number constraint condition of the single cells so that the amount of hydrogen in the fuel passed into each single cell in the fuel cell stack per unit time is equal, which can reduce the risk of over-utilization of the single cells, and improve the stability and reliability of the fuel cell operation while effectively improving the fuel utilization and power generation efficiency.

[0034] The present invention also provides a fuel cell system with a multi-cascade structure, which forms a fuel cell group by connecting the fourth fuel flow paths of multiple fuel stacks in parallel, and connecting the third fuel flow paths of the multiple fuel stack groups in series to form a fuel cell system, so that the fuel exhaust gas discharged from the previous stage flows into the next stage for reaction, thereby realizing the recycling of fuel and improving fuel utilization and power generation efficiency; in addition, the number of fuel stacks is limited by the number constraint condition of the fuel stacks so that the amount of hydrogen in the fuel passed into each fuel stack in the fuel cell system per unit time is equal, which can reduce the risk of over-utilization of the fuel stacks, and improve the stability and reliability of the system operation while effectively improving the fuel utilization and power generation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solution in the embodiments of the present invention, the following introduction is made to the drawings required for use in the embodiments of the present invention. It should be understood that the drawings introduced below are only for the convenience of clearly describing some embodiments of the technical solution of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative work.

[0036] Figure 1 A schematic diagram of the structure of a multi-cascade structured battery stack provided by an embodiment of the present invention;

[0037] Figure 2 A schematic structural diagram of a fuel cell system with a multi-cascade structure provided in an embodiment of the present invention. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is further described in detail below in conjunction with the accompanying drawings and examples. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. When the following description refers to the drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with the embodiments of the present application. They are only examples of devices and methods consistent with some aspects of the embodiments of the present application as detailed in the attached claims.

[0039] It is understood that the terms "first", "second", etc. used in this application can be used to describe various concepts in this article, but unless otherwise specified, these concepts are not limited by these terms. These terms are only used to distinguish one concept from another concept. For example, without departing from the scope of the embodiment of the present application, the first information may also be referred to as the second information, and similarly, the second information may also be referred to as the first information. Depending on the context, the words "if" and "if" as used herein can be interpreted as "at the time of" or "when" or "in response to determination".

[0040] The terms "at least one", "multiple", "each", "any", etc. used in this application, at least one includes one, two or more, multiple includes two or more, each refers to each of the corresponding multiple, and any refers to any one of the multiple.

[0041] A fuel cell is an electrochemical device that can directly convert chemical energy stored in fuel and oxidant into electrical energy. Fuel cells are usually stacked as single cells; one or more stacks and other modules such as gas management modules, water treatment modules, power management modules, and main control modules constitute a fuel cell system.

[0042] In order to improve the power generation power, power generation efficiency and fuel utilization rate of fuel cell systems and stacks, multiple stacks or multiple single cells are usually designed in series and parallel. However, in the current design of fuel cell systems and stacks, there is often a risk of imbalance in the ratio of the number of stacks and single cells, resulting in a decrease in the overall fuel utilization rate of the fuel cell system and stack.

[0043] To this end, an embodiment of the present invention proposes a multi-cascade structured fuel cell stack, which forms a battery array by connecting the second fuel flow paths of multiple single cells in parallel, and connects the first fuel flow paths of the multi-stage battery array in series to form a fuel cell stack, so that the fuel exhaust gas discharged from the previous stage flows into the next stage for reaction, thereby realizing the recycling of fuel and improving fuel utilization and power generation efficiency. In addition, the number of single cells is limited by the constraint condition of the number of single cells so that the amount of hydrogen in the fuel passed into each single cell in the fuel cell stack per unit time is equal, which can reduce the risk of over-utilization of single cells, and improve the stable reliability of the fuel cell operation while effectively improving the fuel utilization and power generation efficiency.

[0044] Reference Figure 1 , Figure 1 A structural schematic diagram of a multi-cascade structure battery stack provided in an embodiment of the present invention, an embodiment of the present invention proposes a multi-cascade structure battery stack, including a multi-stage battery array connected in series, a first fuel flow path and a second fuel flow path, each stage of the battery array includes a plurality of single cells connected in parallel, the battery arrays at each stage are connected through the first fuel flow path, and the single cells in the same stage of the battery array are connected through the second fuel flow path, wherein the number of single cells in each stage of the battery array and the array fuel utilization rate corresponding to the battery array at each stage satisfy a first single cell number constraint condition, and the number of single cells in the previous and next stage battery arrays and the battery fuel utilization rate corresponding to each single cell in the previous stage battery array satisfy a second single cell number constraint condition, so that the amount of hydrogen of fuel passed into each single cell per unit time is equal when the battery stack is operating stably.

[0045] It should be noted that the equal hydrogen amount A0 means that the amount of the fuel passed into each single cell per unit time converted into equivalent hydrogen is equal. In addition, the arithmetic mean of the equal hydrogen amount of the fuel passed into each single cell is A. If the difference between a single cell and A is within ±5%, it can also be considered that the equal hydrogen amount A0 of the fuel of the single cell is equal to that of each single cell.

[0046] When the array fuel utilization rate corresponding to the first-stage battery array is greater than or equal to 50%, it is determined that the battery stack is operating stably.

[0047] Exemplarily, the battery stack of the embodiment of the present invention includes C1, C2 to C x The number of single batteries in each level of battery array is N1, N2 to N x, and N1>N2>...>N x , N1, N2 to N x are all positive integers, and x≥2.

[0048] The fuel gas is input into each battery array in series, and then input into each single battery array in parallel in each battery array, so that the remaining fuel gas after the reaction of the previous battery array flows into the next battery array to participate in the reaction. x-1 and C x The fuel is connected through the first fuel flow path, C x-1 The fuel outlet of each single cell in the upper battery array is connected to the first fuel flow path through the fuel exhaust branch pipe, so that the fuel exhaust of each single cell in the upper battery array converges into the first fuel flow path; x The fuel inlet of each single cell in the next-level battery array is connected to the first fuel flow path through the fuel intake branch pipe, so that the fuel in the first fuel flow path is diverted to each single cell in the next-level battery array.

[0049] As a further optional implementation, the number of single batteries in each level of battery array and the array fuel utilization rate corresponding to each level of battery array satisfy a first single battery number constraint condition, and the first single battery number constraint condition is:

[0050]

[0051] Among them, N x Indicates C x N1 represents the number of single cells in the C1-th level battery array, and η i Indicates C i The array fuel utilization rate corresponding to the level battery array, i and x are both positive integers and i∈[1,x-1].

[0052] Specifically, let C1, C2 to C x The array gas utilization rates corresponding to the multi-level battery arrays are η1, η2 to η x , then the C x The number of single cells in the battery array is N x Satisfies the following formula:

[0053] N x =N x-1 ×(1-η x-1 )

[0054] According to the above formula, we can further get the C x The number of single cells in the battery array is N x The following formula is satisfied (i.e. the first battery quantity constraint):

[0055]

[0056] It should be noted that the embodiment of the present invention designs the fuel utilization rate of each level of battery array to meet the requirements of the first single battery quantity constraint condition, so that the battery stack can automatically achieve equal hydrogen amount A0 of fuel passing into each single battery in each level of battery array per unit time during normal operation, without the need for flow control through active devices.

[0057] As a further optional implementation, the number of cells in the previous and next battery arrays and the battery fuel utilization rate corresponding to each cell in the previous battery array satisfy a second cell number constraint condition, and the second cell number constraint condition is:

[0058]

[0059] Among them, N x Indicates C x The number of cells in the battery array, N x-1 Indicates C x-1 The number of cells in the battery array, γ i Indicates C x-1 The battery fuel utilization rate corresponding to the i-th single battery in the battery array, i and x are both positive integers and i∈[1, N x-1 ].

[0060] Specifically, let C x-1 The battery array has N x-1 The fuel utilization rate of each single cell is γ1, γ2 to C x The battery array has N x single battery, then N x The following formula is satisfied (i.e. the second battery quantity constraint):

[0061]

[0062] It should be noted that the embodiment of the present invention designs the number of single cells in two adjacent levels of battery arrays and the fuel utilization rate of each single cell in the previous level of battery array to meet the requirements of the second single cell number constraint condition, so that the battery stack can automatically achieve equal hydrogen amount A0 of fuel passing into each single cell per unit time during normal operation, without the need for flow control through active devices.

[0063] As a further optional implementation, the stack fuel utilization rate corresponding to the stack and the array fuel utilization rates corresponding to each level of battery array satisfy the stack fuel utilization rate constraint condition, and the stack fuel utilization rate constraint condition is:

[0064]

[0065] Among them, η 堆 Indicates the fuel utilization rate of the fuel cell stack, N i Indicates C i The number of cells in the battery array, η i Indicates C i The array fuel utilization rate corresponding to the level battery array, i and x are both positive integers and i∈[1,x].

[0066] Specifically, the fuel utilization rate of the fuel stack corresponding to the fuel stack is η 堆 , C1, C2 to C x The array gas utilization rates corresponding to the multi-level battery arrays are η1, η2 to η x , then the stack fuel utilization rate η 堆 The following formula is satisfied (i.e., the fuel utilization constraint of the fuel stack):

[0067]

[0068] It should be noted that when the stack fuel utilization rate corresponding to the battery stack and the array fuel utilization rate of each level of battery array meet the above-mentioned stack fuel utilization rate constraint conditions, it can ensure that the single cells of each level of battery array will not be overloaded, improve the life of the single cell, and keep the overall utilization rate of the battery stack high.

[0069] As an optional embodiment, the stack fuel utilization rate satisfies 60%≤η 堆 ≤99% or 70%≤η 堆 ≤95%, the array fuel utilization rate corresponding to each level of battery array meets 30%≤η x ≤75% or 50%≤η x ≤75%, where η x Indicates C x The array fuel utilization rate corresponding to the level battery array, x is a positive integer.

[0070] Specifically, the fuel utilization rate of the fuel stack corresponding to the fuel stack is set to satisfy 60%≤η 堆 ≤99% or 70%≤η 堆 ≤95%, in order to maximize the use of fuel within the range where the stack can operate stably and reduce the fuel consumption cost; the array fuel utilization rate corresponding to each level of battery array is set to meet 30%≤η x ≤75% or 50%≤η x ≤75% to optimize the fuel utilization distribution of each level of battery array and improve the overall fuel utilization and performance of the entire battery stack.

[0071] Those skilled in the art will appreciate that the limited ranges of the fuel utilization rate of the battery stack and the array fuel utilization rates corresponding to each level of the battery array may also be selected according to actual needs.

[0072] As a further optional implementation, the number of single batteries in each level of the battery array satisfies a third single battery number constraint condition, and the third single battery number constraint condition is:

[0073] When the battery stack includes a first-stage battery array and a second-stage battery array connected in series, the number of single cells in the first-stage battery array and the number of single cells in the second-stage battery array satisfy N1:N2 is one of 2:1, 3:1, 42:13, 39:12 or 4:1, wherein N1 represents the number of single cells in the first-stage battery array, and N2 represents the number of single cells in the second-stage battery array;

[0074] When the battery stack includes a first-level battery array, a second-level battery array and a third-level battery array connected in series, the number of single cells in the first-level battery array, the number of single cells in the second-level battery array and the number of single cells in the third-level battery array satisfy N1:N2:N3, which is one of 9:3:1, 39:12:4 or 42:13:4, wherein N1 represents the number of single cells in the first-level battery array, N2 represents the number of single cells in the second-level battery array, and N3 represents the number of single cells in the third-level battery array.

[0075] Optionally, the battery stack in the embodiment of the present invention further includes a fuel replenishment flow path, which is arranged on the first fuel flow path between two adjacent battery arrays. When the operation of the battery stack fluctuates or fails, resulting in the remaining fuel discharged from the upper battery array failing to meet the "equal amount of hydrogen A0 of fuel passed into each single cell per unit time" in the lower battery array, the remaining fuel discharged from the upper battery array can be mixed with the replenishment fuel and flow into the lower battery array through the fuel replenishment flow path.

[0076] Specifically, suppose two adjacent battery arrays are C x-1 and C x , C can be determined by the following formula x The fuel cell array needs to be refueled. When the following equation is satisfied, the fuel cell system controls C x-1 and C x The fuel replenishment flow path between the two-stage battery array is fed with replenishment fuel, and the replenishment fuel is x-1 The remaining fuel discharged from the first battery array is mixed and flows into the C x In the battery array:

[0077] N x >N x-1 ×(1-η x-1 )

[0078] Among them, η x-1 Indicates C x-1 Array gas utilization rate corresponding to the level 1 battery array.

[0079] Furthermore, let C1, C2 to C x The array gas utilization rates corresponding to the multi-level battery arrays are η1, η2 to η x , then the C x The number of single cells in the battery array is N x Satisfies the following formula:

[0080]

[0081] Among them, Q x-1 Indicates C per unit time x-1 and C x The same amount of hydrogen as the supplementary fuel introduced between two adjacent battery arrays.

[0082] When x≥3, transform the above formula, then the C x The number of single cells in the battery array is N x Satisfies the following formula:

[0083]

[0084] Among them, Q i Indicates C per unit time i and C i+1 The amount of hydrogen of the supplementary fuel introduced between two adjacent battery arrays, i and k are both positive integers, and i∈[1, x-1], k∈[2, x-1].

[0085] When x=2, substituting x=2 into the above formula, the number of single cells N2 in the C2-level battery array satisfies the following formula:

[0086]

[0087] Wherein, Q1 represents the amount of hydrogen equivalent of the supplementary fuel introduced between two adjacent battery arrays of C1 and C2 per unit time.

[0088] It should be noted that when the fuel cell stack needs to be refueled, by designing the number of single cells in the two adjacent battery arrays, the array fuel utilization rate of the previous battery array, and the equal hydrogen amount of fuel that needs to be refueled between the two adjacent stages to meet the requirements specified by the above formula, the fuel cell stack can automatically achieve equal hydrogen amount A0 of fuel entering each single cell per unit time during abnormal operation without the need for flow control through active devices.

[0089] Furthermore, the equivalent hydrogen amount Q of the supplementary fuel iSatisfy the following formula (select the best one):

[0090] Q i ≥A0×[N i+1 -N i ×(1-η i )]

[0091] Further, suppose that x-1 The battery array has N x-1 The battery fuel utilization rate of each single battery is γ1, γ2 to C x The battery array has N x single battery, then the C x The number of single cells in the battery array is N x Satisfies the following formula:

[0092]

[0093] It should be noted that when the system needs to refuel, by designing the number of single cells in the two adjacent battery arrays, the battery fuel utilization rate corresponding to each single cell in the previous battery array, and the equal hydrogen amount of fuel that needs to be refilled between the two adjacent levels to meet the requirements specified by the above formula, the battery stack can automatically achieve equal hydrogen amount A0 of fuel entering each single cell per unit time during abnormal operation, without the need for flow control through active devices.

[0094] The above is a description of the battery stack of the embodiment of the present invention. It can be recognized that, compared with the battery stack in the prior art, the present invention forms a battery array by connecting the second fuel flow paths of multiple single cells in parallel, and connecting the first fuel flow paths of the multi-stage battery array in series to form a battery stack, so that the fuel exhaust gas discharged from the previous stage flows into the next stage for reaction, which can realize the recycling of fuel and improve the fuel utilization rate and power generation efficiency; in addition, by limiting the amount of hydrogen in the fuel introduced into each single cell per unit time to be equal, the risk of over-utilization of the single cell can be reduced, and the stability and reliability of the battery stack operation can be improved while effectively improving the fuel utilization rate and power generation efficiency.

[0095] An embodiment of the present invention also proposes a fuel cell system with a multi-cascade structure, which forms a fuel cell group by connecting the fourth fuel flow paths of multiple fuel stacks in parallel, and connecting the third fuel flow paths of the multiple fuel stack groups in series to form a fuel cell system, so that the fuel exhaust gas discharged from the previous stage flows into the next stage for reaction, thereby realizing the recycling of fuel and improving fuel utilization and power generation efficiency; in addition, the number of fuel stacks is limited by the number constraint condition of the fuel stacks so that the amount of hydrogen in the fuel passed into each fuel stack in the fuel cell system per unit time is equal, which can reduce the risk of over-utilization of the fuel stacks, and improve the stability and reliability of the system operation while effectively improving the fuel utilization and power generation efficiency.

[0096] Reference Figure 2 , Figure 2 A structural schematic diagram of a fuel cell system with a multi-cascade structure provided in an embodiment of the present invention, an embodiment of the present invention proposes a fuel cell system with a multi-cascade structure, including multiple stages of series-connected fuel cell groups, a third fuel flow path, and a fourth fuel flow path, each stage of the fuel cell group includes multiple parallel fuel cell stacks, each stage of the fuel cell group is connected through the third fuel flow path, and the fuel cell stacks in the same stage of the fuel cell group are connected through the fourth fuel flow path, wherein the number of fuel cell stacks in each stage of the fuel cell group and the fuel utilization rate of the fuel cell stack group corresponding to each stage of the fuel cell group satisfy a first fuel cell stack number constraint condition, and the number of fuel cell stacks in the previous and next stage fuel cell stack groups and the fuel utilization rate of the fuel cell stacks corresponding to each fuel cell stack in the previous stage of the fuel cell stack group satisfy a second fuel cell stack number constraint condition, so that the amount of hydrogen of fuel passed into each fuel cell stack per unit time is equal when the fuel cell system is operating stably.

[0097] It should be noted that the equal amount of hydrogen A0 means that the amount of the fuel introduced into each stack per unit time converted into equivalent hydrogen is equal. In addition, the arithmetic mean of the equal amount of hydrogen introduced into each stack is A. If the difference between a certain stack and A is within ±5%, it can also be considered that the equal amount of hydrogen A0 of the fuel of the stack is equal to that of each stack.

[0098] When the fuel utilization rate of the fuel cell stack corresponding to the first-stage fuel cell stack is greater than or equal to 50%, it is determined that the fuel cell system is operating stably.

[0099] Exemplarily, the fuel cell system of the embodiment of the present invention includes D1, D2 to D y The number of stacks in each level of stack group is M1, M2 to M y , and M1>M2>...>M y , M1, M2 to M y are all positive integers, and y≥2.

[0100] The fuel gas is input into each level of the stack in series, and then input into each stack in each level of the stack in parallel, so that the remaining fuel gas after the reaction of the previous level of the stack flows into the next level of the stack to participate in the reaction. y-1 and D y The fuel is connected through the third fuel flow path, D y-1 The fuel outlets of each fuel cell in the first-stage fuel cell group are connected to the third fuel flow path through the fuel exhaust branch pipe, so that the fuel exhaust of each fuel cell in the last-stage fuel cell group converges into the third fuel flow path; y The fuel inlet of each fuel cell in the first-stage fuel cell group is connected to the third fuel flow path through the fuel intake branch pipe, so that the fuel in the third fuel flow path is diverted to each fuel cell in the next-stage fuel cell group.

[0101] It should be emphasized that those skilled in the art can understand that the battery stack in the battery stack group can be a battery stack with a multi-cascade structure as mentioned above, or a common battery stack without a multi-cascade structure, such as a battery stack formed by stacking multiple single cells in series, and the type of battery stack in the battery stack group is not limited in the embodiments of the present invention. The fuel cell system can be applied to various types of battery stacks to meet the diversified needs and performance optimization requirements in different application scenarios.

[0102] As a further optional implementation, the number of battery stacks in each level of battery stack group and the fuel utilization rate of the battery stack group corresponding to each level of battery stack group satisfy a first battery stack number constraint condition, and the first battery stack number constraint condition is:

[0103]

[0104] Among them, M y Indicates D y M1 represents the number of stacks in the D1st-level stack group, μ j Indicates D j The fuel utilization rate of the fuel cell group corresponding to the first-level fuel cell group, j and y are both positive integers and j∈[1, y-1].

[0105] Specifically, let D1, D2 to D y The fuel cell gas utilization rates of the multi-stage fuel cell groups are μ1, μ2 to μ y , then D y The number of stacks in the stack group M y Satisfies the following formula:

[0106] M y =M y-1 ×(1-μ y-1 )

[0107] According to the above formula, we can further set the D y The number of stacks in the stack group M y Satisfy the following formula (i.e. the first battery stack quantity constraint):

[0108]

[0109] It should be noted that the embodiment of the present invention designs the fuel utilization rate of each level of the fuel cell group to meet the requirements of the first fuel cell quantity constraint condition, so that the fuel cell stack can automatically achieve equal hydrogen amount A0 of fuel passed into each fuel cell stack in each level of the fuel cell group per unit time during normal operation, without the need for flow control through active devices.

[0110] As a further optional implementation, the number of stacks in the previous and next stage stack groups and the stack fuel utilization rate corresponding to each stack in the previous stage stack group meet the second stack number constraint condition, and the second stack number constraint condition is:

[0111]

[0112] Among them, M y Indicates D y The number of stacks in the stack group, M y-1 Indicates D y-1 The number of stacks in the stack group, δ j Indicates D y-1 The fuel utilization rate of the jth stack in the stack group, j and y are both positive integers and j∈[1,M y-1 ].

[0113] Specifically, let D y-1 The stack has M y-1 The fuel utilization rates of each stack are δ1, δ2 to δ (My-1) , D y The stack has M y If there are a number of battery stacks, then M y Satisfy the following formula (i.e. the second battery stack quantity constraint):

[0114]

[0115] It should be noted that the embodiment of the present invention designs the number of fuel cells in the latter-stage fuel cell group and the fuel utilization rate of each fuel cell in the former-stage fuel cell group to meet the requirements of the second fuel cell number constraint condition, so that the fuel cell system can automatically achieve equal hydrogen amount A0 of fuel passing into each fuel cell stack per unit time during normal operation, without the need for flow control through active devices.

[0116] As a further optional implementation, the system fuel utilization rate corresponding to the fuel cell system and the fuel utilization rate of the stack group corresponding to each level of the stack group satisfy the system fuel utilization rate constraint condition, and the system fuel utilization rate constraint condition is;

[0117]

[0118] Among them, μ 总 Represents the system fuel utilization, M y Indicates D y The number of stacks in the D-level stack group, μj represents the j The fuel utilization rate of the fuel cell group corresponding to the first-level fuel cell group, j and y are positive integers and j∈[1,y].

[0119] Specifically, the system fuel utilization rate of the fuel cell system is μ 总 , D1, D2 to D y The fuel cell gas utilization rates of the multi-stage fuel cell groups are μ1, μ2 to μ y , then the system fuel utilization rate η 总 The following formula is satisfied (i.e., the system fuel utilization constraint):

[0120]

[0121] It should be noted that when the system fuel utilization rate corresponding to the fuel cell system and the fuel utilization rate of the fuel cell groups at each level meet the above-mentioned system fuel utilization rate constraint conditions, it can ensure that the fuel cell stacks at each level will not be overloaded, improve the life of the fuel cell stacks, and keep the overall fuel cell system at a high utilization rate.

[0122] As an optional implementation, the system fuel utilization rate satisfies 60%≤μ 总 ≤99% or 70%≤μ 总 ≤95%, the fuel utilization rate of the fuel stack corresponding to each level of fuel stack meets 30%≤μ y ≤75% or 50%≤μ y ≤75%, where μ y Indicates D y The fuel utilization rate of the fuel cell group corresponding to the first-level fuel cell group, y is a positive integer.

[0123] Specifically, the system fuel utilization rate corresponding to the fuel cell system is set to satisfy 60%≤μ 总 ≤99% or 70%≤μ 总 ≤95%, in order to maximize the use of fuel within the range of stable operation of the system and reduce fuel consumption costs; set the fuel utilization rate of the fuel stack corresponding to each level of fuel stack to meet 30%≤μ y ≤75% or 50%≤μ y≤75% to optimize the fuel utilization distribution of each level of the fuel stack group and improve the overall fuel utilization and performance of the entire system.

[0124] Those skilled in the art will appreciate that the limited ranges of the system fuel utilization rate and the fuel utilization rates of the fuel stack groups corresponding to each level of the fuel stack groups may also be selected according to actual needs.

[0125] As a further optional implementation, the number of battery stacks in each level of battery stack group satisfies a third battery stack number constraint condition, and the third battery stack number constraint condition is:

[0126] When the fuel cell system comprises a first-stage stack group and a second-stage stack group connected in series, the number of stacks in the first-stage stack group and the number of stacks in the second-stage stack group satisfy M1:M2 is one of 2:1, 3:1, 42:13, 39:12 or 4:1, wherein M1 represents the number of stacks in the first-stage stack group, and M2 represents the number of stacks in the second-stage stack group;

[0127] When the fuel cell system includes a first-stage fuel cell group, a second-stage fuel cell group and a third-stage fuel cell group connected in series, the number of fuel cells in the first-stage fuel cell group, the number of fuel cells in the second-stage fuel cell group and the number of fuel cells in the third-stage fuel cell group satisfy M1:M2:M3, which is one of 9:3:1, 39:12:4 or 42:13:4, wherein M1 represents the number of fuel cells in the fuel cell group, M2 represents the number of fuel cells in the second-stage fuel cell group, and M3 represents the number of fuel cells in the third-stage fuel cell group.

[0128] Optionally, the fuel cell system in the embodiment of the present invention further includes a fuel replenishment flow path, which is arranged on the third fuel flow path between two adjacent stack groups. When the operation of the fuel cell system fluctuates or fails, resulting in the remaining fuel discharged from the previous stack group failing to meet the "equal amount of hydrogen A0 of the fuel passed into each stack per unit time" in the next stack group, the remaining fuel discharged from the previous stack group can be mixed with the replenishment fuel and flow into the next stack group through the fuel replenishment flow path.

[0129] Specifically, suppose two adjacent stack groups are D y-1 and D y , the Dth y The fuel cell system controls D y-1 and D y The fuel replenishment flow path between the two-stage fuel stack group is connected to the replenishment fuel, and the replenishment fuel is connected to the D y-1 The remaining fuel discharged from the first stack group is mixed and flows into the D y In the stack group:

[0130] My >M y-1 ×(1-μ y-1 )

[0131] Among them, μ y-1 Indicates D y-1 The gas utilization rate of the fuel cell group corresponding to the first-level fuel cell group.

[0132] Further, let D1, D2 to D y The fuel cell gas utilization rates of the multi-stage fuel cell groups are μ1, μ2 to μ y , then D y The number of stacks in the stack group M y Satisfies the following formula:

[0133]

[0134] Among them, Q y-1 Indicates D per unit time y-1 and D y The same amount of hydrogen as the supplementary fuel introduced between two adjacent fuel cell stack groups.

[0135] When y≥3, transform the above formula, then the D y The number of stacks in the stack group M y Satisfies the following formula:

[0136]

[0137] Among them, Q j Indicates D per unit time j and D j+1 The amount of hydrogen in the supplementary fuel introduced between two adjacent fuel cell stacks is equal, j and k are both positive integers, and j∈[1, y-1], k∈[2, y-1].

[0138] When y=2, substitute y=2 into the above formula, and the number of stacks M2 of the D2-level stack group satisfies the following formula:

[0139]

[0140] Among them, Q1 represents the amount of hydrogen of supplementary fuel introduced between two adjacent fuel cell stacks D1 and D2 per unit time.

[0141] It should be noted that when the system needs to refuel, by designing the number of fuel cells in two adjacent stages, the fuel utilization rate of the previous stage, and the equal hydrogen amount of fuel that needs to be refilled between two adjacent stages to meet the requirements specified in the above formula, the system can automatically achieve equal hydrogen amount A0 of fuel passing into each fuel stack per unit time during abnormal operation without the need for flow control through active devices.

[0142] Furthermore, the equivalent hydrogen amount Q of the supplementary fuel j Satisfy the following formula (select the best one):

[0143] Q j ≥A0×[M j+1 -M j ×(1-μ j )]

[0144] Further, suppose D y-1 The stack has M y-1 The fuel utilization rates of each fuel stack are δ1, δ2, and No. D y The stack has M y The Dth y The number of stacks in the stack group M y Satisfies the following formula:

[0145]

[0146] It should be noted that when the system needs to refuel, by designing the number of fuel cells in two adjacent stages of fuel cell groups, the fuel utilization rate of each fuel cell in the previous stage of fuel cell group, and the equal hydrogen amount of fuel that needs to be refilled between two adjacent stages to meet the requirements specified by the above formula, the system can automatically achieve equal hydrogen amount A0 of fuel passing into each fuel cell per unit time during abnormal operation without the need for flow control through active devices.

[0147] The above is a description of the fuel cell system of the embodiment of the present invention. It can be recognized that, compared with the fuel cell system in the prior art, the present invention forms a fuel cell group by connecting the fourth fuel flow paths of multiple stacks in parallel, and connecting the third fuel flow paths of the multi-stage stack group in series to form a fuel cell system, so that the fuel exhaust gas discharged from the previous stage flows into the next stage for reaction, which can realize the recycling of fuel and improve the fuel utilization rate and power generation efficiency; in addition, by limiting the amount of hydrogen in the fuel introduced into each stack per unit time to be equal, the risk of over-utilization of the stack can be reduced, and the stability and reliability of the system operation can be improved while effectively improving the fuel utilization rate and power generation efficiency.

[0148] In some selectable embodiments, the function / operation mentioned in the block diagram may not occur in the order mentioned in the operation diagram. For example, depending on the function / operation involved, the two boxes shown in succession can actually be executed substantially simultaneously or the above-mentioned boxes can sometimes be executed in reverse order. In addition, the embodiment presented and described in the flow chart of the present invention is provided by way of example, for the purpose of providing a more comprehensive understanding of technology. The disclosed method is not limited to the operation and logic flow presented herein. Selectable embodiments are expected, wherein the order of various operations is changed and the sub-operation of a part for which is described as a larger operation is performed independently.

[0149] In addition, although the present invention is described in the context of functional modules, it should be understood that, unless otherwise specified to the contrary, one or more of the above-mentioned functions and / or features can be integrated into a single physical device and / or software module, or one or more functions and / or features can be implemented in a separate physical device or software module. It is also understood that a detailed discussion of the actual implementation of each module is unnecessary for understanding the present invention. More specifically, in view of the properties, functions and internal relationships of the various functional modules in the device disclosed herein, the actual implementation of the module will be understood within the conventional skills of the engineer. Therefore, those skilled in the art can implement the present invention set forth in the claims without excessive experimentation using ordinary techniques. It is also understood that the specific concepts disclosed are merely illustrative and are not intended to limit the scope of the present invention, which is determined by the full scope of the appended claims and their equivalents.

[0150] If the above functions are implemented in the form of software functional units and sold or used as independent products, they can be stored in a computer-readable storage medium. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art or the part of the technical solution, can be embodied in the form of a software product. The computer software product is stored in a storage medium, including several instructions for a computer device (which can be a personal computer, a server, or a network device, etc.) to perform all or part of the steps of the above methods of each embodiment of the present invention. The aforementioned storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), disk or optical disk and other media that can store program codes.

[0151] The logic and / or steps represented in the flowchart or otherwise described herein, for example, can be considered as an ordered list of executable instructions for implementing logical functions, and can be embodied in any computer-readable medium for use by an instruction execution system, device or apparatus (such as a computer-based system, a system including a processor, or other system that can fetch instructions from an instruction execution system, device or apparatus and execute instructions), or in conjunction with such instruction execution systems, devices or apparatuses. For the purposes of this specification, "computer-readable medium" can be any device that can contain, store, communicate, propagate or transmit a program for use by an instruction execution system, device or apparatus, or in conjunction with such instruction execution systems, devices or apparatuses.

[0152] More specific examples of computer-readable media (a non-exhaustive list) include the following: an electrical connection with one or more wires (electronic device), a portable computer disk case (magnetic device), a random access memory (RAM), a read-only memory (ROM), an erasable and editable read-only memory (EPROM or flash memory), an optical fiber device, and a portable compact disk read-only memory (CDROM). In addition, the computer-readable medium may even be a paper or other suitable medium on which the above-mentioned program is printed, since the above-mentioned program can be obtained electronically, for example, by optically scanning the paper or other medium, followed by editing, deciphering or processing in other suitable ways as necessary, and then stored in a computer memory.

[0153] It should be understood that the various parts of the present invention can be implemented by hardware, software, firmware or a combination thereof. In the above-mentioned embodiments, a plurality of steps or methods can be implemented by software or firmware stored in a memory and executed by a suitable instruction execution system. For example, if implemented by hardware, as in another embodiment, it can be implemented by any one of the following technologies known in the art or their combination: a discrete logic circuit having a logic gate circuit for implementing a logic function for a data signal, a dedicated integrated circuit having a suitable combination of logic gate circuits, a programmable gate array (PGA), a field programmable gate array (FPGA), etc.

[0154] In the above description of this specification, the description with reference to the terms "one embodiment / example", "another embodiment / example" or "certain embodiments / examples" etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0155] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

[0156] The above is a specific description of the preferred implementation of the present invention, but the present invention is not limited to the embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. A multi-cascade structured battery stack, characterized in that: It comprises a multi-stage battery array connected in series, a first fuel flow path and a second fuel flow path, each stage of the battery array comprises a plurality of single batteries connected in parallel, the battery arrays at each stage are connected through the first fuel flow path, and the single batteries in the battery array at the same stage are connected through the second fuel flow path, wherein the number of single batteries in the battery arrays at each stage and the array fuel utilization rate corresponding to the battery arrays at each stage satisfy a first single battery number constraint condition, and the number of single batteries in the battery arrays at the previous and next stages and the battery fuel utilization rate corresponding to each single battery in the battery array at the previous stage satisfy a second single battery number constraint condition, so that the amount of hydrogen in the fuel passing into each single battery per unit time is equal when the battery stack is in stable operation; The first single battery quantity constraint condition is: Among them, N x Indicates C x N1 represents the number of single batteries in the battery array of level C1, N2 represents the number of single batteries in the battery array of level C1, i Indicates C i The array fuel utilization rate corresponding to the battery array, i and x are both positive integers and i∈[1, x-1]; The second battery quantity constraint condition is: Among them, N x Indicates C x The number of cells in the battery array, N x-1 Indicates C x-1 The number of cells in the battery array, γ i Indicates C x-1 The battery fuel utilization rate corresponding to the ith battery in the battery array, i and x are both positive integers and i∈[1, N x-1 ].

2. A multi-cascade structured fuel cell stack according to claim 1, characterized in that: The stack fuel utilization rate corresponding to the stack and the array fuel utilization rate corresponding to each level of the battery array meet the stack fuel utilization rate constraint condition, and the stack fuel utilization rate constraint condition is: Among them, η 堆 represents the fuel utilization rate of the stack, Ni represents the C i The number of cells in the battery array, n i Indicates C i The array fuel utilization rate corresponding to the battery array, i and x are both positive integers and i∈[1,x].

3. A multi-cascade structured fuel cell stack according to claim 2, characterized in that: The fuel utilization rate of the fuel stack satisfies 60%≤η 堆 ≤99% or 70%≤η 堆 ≤95%, the array fuel utilization rate corresponding to each level of the battery array satisfies 30%≤η x ≤75% or 50%≤η x ≤75%, where η x Indicates C x The array fuel utilization rate corresponding to the battery array, x is a positive integer.

4. The multi-cascade structured fuel cell stack according to claim 1, characterized in that: The number of cells in each level of the battery array satisfies a third cell number constraint condition, and the third cell number constraint condition is: When the battery stack includes a first-level battery array and a second-level battery array connected in series, the number of single batteries in the first-level battery array and the number of single batteries in the second-level battery array satisfy N1:N2 is one of 2:1, 3:1, 42:13, 39:12 or 4:1, wherein N1 represents the number of single batteries in the first-level battery array, and N2 represents the number of single batteries in the second-level battery array; When the battery stack includes a first-level battery array, a second-level battery array and a third-level battery array connected in series, the number of single cells in the first-level battery array, the number of single cells in the second-level battery array and the number of single cells in the third-level battery array satisfy N1:N2:N3, which is one of 9:3:1, 39:12:4 or 42:13:4, wherein N1 represents the number of single cells in the first-level battery array, N2 represents the number of single cells in the second-level battery array, and N3 represents the number of single cells in the third-level battery array.

5. A fuel cell system with a multi-cascade structure, characterized in that: The method comprises a plurality of series-connected stack groups, a third fuel flow path, and a fourth fuel flow path, wherein each stack group comprises a plurality of parallel stacks, the stack groups at each level are connected through the third fuel flow path, and the stacks in the stack group at the same level are connected through the fourth fuel flow path, wherein the number of stacks in each level of the stack group and the stack group fuel utilization rate corresponding to each level of the stack group satisfy a first stack number constraint condition, and the number of stacks in the stack groups at the previous and next levels and the stack fuel utilization rate corresponding to each stack in the stack group at the previous level satisfy a second stack number constraint condition, so that the amount of hydrogen in the fuel passed into each stack per unit time is equal when the fuel cell system is in stable operation; The first battery stack quantity constraint condition is: Among them, M y Indicates D y M1 represents the number of stacks in the stack group of level D1, μ j Indicates D j The fuel utilization rate of the stack group corresponding to the stack group, j and y are both positive integers and j∈[1, y-1]; The second battery stack quantity constraint condition is: Among them, M y Indicates D y The number of stacks in the stack group of the level, M y-1 Indicates D y-1 The number of stacks in the stack group of the level, δ j Indicates D y-1 The fuel utilization rate of the fuel cell corresponding to the jth fuel cell in the fuel cell group, j and y are both positive integers and j∈[1, M y-1 ].

6. A fuel cell system with a multi-cascade structure according to claim 5, characterized in that: The system fuel utilization rate corresponding to the fuel cell system and the fuel utilization rate of the fuel stack group corresponding to each level of the fuel stack group satisfy the system fuel utilization rate constraint condition, and the system fuel utilization rate constraint condition is; Among them, μ 总 represents the fuel utilization rate of the system, M y Indicates D y The number of stacks in the stack group of the level, μ j Indicates D j The fuel utilization rate of the fuel stack group corresponding to the level of the fuel stack group, j and y are positive integers and j∈[1,y].

7. A fuel cell system with a multi-cascade structure according to claim 6, characterized in that: The system fuel utilization rate meets 60%≤μ 总 ≤99% or 70%≤μ 总 ≤95%, the fuel utilization rate of the stack group corresponding to each level of the stack group meets 30%≤μ y ≤75% or 50%≤μ y ≤75%, where μ y Indicates D y The fuel utilization rate of the fuel stack group corresponding to the level of the fuel stack group, y is a positive integer.

8. A fuel cell system with a multi-cascade structure according to claim 5, characterized in that: The number of battery stacks in each level of the battery stack group satisfies the third battery stack number constraint condition, and the third battery stack number constraint condition is: When the fuel cell system comprises a first-stage stack group and a second-stage stack group connected in series, the number of stacks in the first-stage stack group and the number of stacks in the second-stage stack group satisfy M1:M2, which is one of 2:1, 3:1, 42:13, 39:12 or 4:1, wherein M1 represents the number of stacks in the first-stage stack group, and M2 represents the number of stacks in the second-stage stack group; When the fuel cell system includes a first-stage fuel cell group, a second-stage fuel cell group and a third-stage fuel cell group connected in series, the number of fuel cells in the first-stage fuel cell group, the number of fuel cells in the second-stage fuel cell group and the number of fuel cells in the third-stage fuel cell group satisfy M1:M2:M3, which is one of 9:3:1, 39:12:4 or 42:13:4, wherein M1 represents the number of fuel cells in the fuel cell group, M2 represents the number of fuel cells in the second-stage fuel cell group, and M3 represents the number of fuel cells in the third-stage fuel cell group.

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