Method for controlling net output power of a fuel cell

Abstract

The application provides a control method of fuel cell net output power. The application determines the corresponding control level according to the size of real-time power consumption of a load, determines the fuel cell net output power based on the entered control level and the size of lithium battery power, and can accurately and reliably meet the fuel cell power supply demand under the scene where the working condition of special application is not allowed to add a hydrogen buffer tank.

Description

TECHNICAL FIELD

[0001] The present application relates to a fuel cell net output power control method. BACKGROUND

[0002] The working principle of hydrogen fuel cell is to input hydrogen and output electricity. In the input aspect, the hydrogen fuel cell has a high requirement for hydrogen purity in order to avoid damage to the hydrogen fuel cell life by impurity gas.

[0003] In the output aspect, it is divided into two parts:

[0004] First, the uncertain load power size (power size within the design range) is a dynamic change, so the methanol reforming hydrogen system has a high requirement for response speed, hydrogen flow supply and dynamic adjustment;

[0005] Second, the lithium battery is dynamically charged and maintained according to the real-time power of the lithium battery. While meeting the power consumption of the load, the surplus is used to charge and maintain the lithium battery. The maintenance also controls the charging current size so as not to affect the normal use of the lithium battery.

[0006] Considering the uncertainty factor of load change, it will inevitably affect the size of fuel cell power generation, and then affect the hydrogen demand of the fuel cell input. The hydrogen production system needs a process or a certain time to produce hydrogen, and it is difficult to meet the demand in real time. Therefore, a certain capacity of hydrogen buffer tank (which can be approximated as a hydrogen storage tank with gas supplement) is generally installed. However, some special application conditions do not allow the installation of hydrogen buffer tank, such as military industry, flammable and explosive chemicals. The existing fuel cell net output power control method cannot meet the power demand of the use of the hydrogen buffer tank. SUMMARY

[0007] The purpose of the present application is to provide a fuel cell net output power control method.

[0008] To solve the above problems, the present application provides a fuel cell net output power control method, comprising:

[0009] According to the size of the real-time power consumption of the load, the corresponding control level is determined;

[0010] Based on the entered control level and the size of the lithium battery power, the fuel cell net output power is determined.

[0011] Further, in the above method, according to the size of the real-time power consumption of the load, the corresponding control level is determined, comprising:

[0012] If the real-time power consumption of the load is greater than or equal to 0 and less than 1 / 4 of the maximum load power consumption, the corresponding first control level is determined;

[0013] determining the net output power of the fuel cell based on the entering control level and the size of the lithium battery power, comprising:

[0014] In the first control level, if the lithium battery power is greater than or equal to the first preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption.

[0015] Further, in the above method, the step S2 of determining the net output power of the fuel cell based on the entering control level and the size of the lithium battery power, comprising:

[0016] In the first control level, if the lithium battery power is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 1 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0017] Further, in the above method, the entering corresponding control level is determined according to the size of the real-time load power consumption, comprising:

[0018] If the real-time load power consumption is greater than or equal to 1 / 4 of the maximum load power consumption and less than 2 / 4 of the maximum load power consumption, it is determined that the corresponding second control level is entered.

[0019] determining the net output power of the fuel cell based on the entering control level and the size of the lithium battery power, comprising:

[0020] In the second control level, if the lithium battery power is greater than or equal to the first preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 1 / 4 of the maximum load power consumption.

[0021] Further, in the above method, the net output power of the fuel cell is determined based on the entering control level and the size of the lithium battery power, comprising:

[0022] In the second control level, if the lithium battery power is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 2 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0023] Further, in the above method, the entering corresponding control level is determined according to the size of the real-time load power consumption, comprising:

[0024] If the real-time load power consumption is greater than or equal to 2 / 4 of the maximum load power consumption and less than 3 / 4 of the maximum load power consumption, it is determined that the corresponding third control level is entered.

[0025] determining the net output power of the fuel cell based on the entering control level and the size of the lithium battery power, comprising:

[0026] In the third control level, if the lithium battery power is greater than or equal to the first preset threshold, the fuel cell net output power is equal to the hydrogen production power consumption plus the system internal loss and 2 / 4 of the maximum load power consumption.

[0027] Further, in the above method, the fuel cell net output power is determined based on the entering control level and the size of the lithium battery power, comprising:

[0028] In the third control level, if the lithium battery power is less than or equal to the second preset threshold, the fuel cell net output power is equal to the hydrogen production power consumption plus the system internal loss and 3 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0029] Further, in the above method, the entering corresponding control level is determined according to the size of the real-time load power consumption, comprising:

[0030] If the real-time load power consumption is greater than or equal to 3 / 4 of the maximum load power consumption and less than or equal to 4 / 4 of the maximum load power consumption, it is determined to enter the corresponding fourth control level.

[0031] The fuel cell net output power is determined based on the entering control level and the size of the lithium battery power, comprising:

[0032] In the fourth control level, if the lithium battery power is greater than or equal to the first preset threshold, the fuel cell net output power is equal to the hydrogen production power consumption plus the system internal loss and 3 / 4 of the maximum load power consumption.

[0033] Further, in the above method, the fuel cell net output power is determined based on the entering control level and the size of the lithium battery power, comprising:

[0034] In the fourth control level, if the lithium battery power is less than or equal to the second preset threshold, the fuel cell net output power is equal to the hydrogen production power consumption plus the system internal loss and 4 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0035] Further, in the above method, the first preset threshold is 80%, and the second preset threshold is 30%.

[0036] Compared with the prior art, the present application can accurately and reliably meet the fuel cell power supply demand in the scene where the working conditions of special application do not allow the installation of a hydrogen buffer tank, while also controlling the maximum allowable charging current of the lithium battery during charging maintenance to ensure the supply and demand balance and normal charging and discharging use of the lithium battery. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is a schematic diagram of net output power of an embodiment of the present application;

[0038] Figure 2 is a control diagram of net output power of a fuel cell of an embodiment of the present application;

[0039] Figure 3 is a schematic diagram of a lithium battery charging limit of an embodiment of the present application. DETAILED DESCRIPTION

[0040] In order to make the above objectives, features and advantages of the present application more apparent, further detailed description of the present application will be given below with reference to the accompanying drawings and specific embodiments.

[0041] As shown in Figure 1 and 2 , the present application provides a control method of net output power of a fuel cell, comprising:

[0042] Step S1, determining the entering corresponding control level according to the size of real-time power consumption of the load;

[0043] Step S2, determining the net output power of the fuel cell based on the entering control level and the size of lithium battery power.

[0044] Here, the present application determines the entering corresponding control level according to the size of real-time power consumption of the load, and determines the net output power of the fuel cell based on the entering control level and the size of lithium battery power, which can accurately and reliably meet the fuel cell power supply demand in the scene where the working conditions of special application do not allow to add a hydrogen buffer tank.

[0045] Figure 1 In the specification, the net output power refers to the net output power of the fuel cell, and the idle power refers to the power required for the entire methanol reforming hydrogen fuel cell system to be self-sufficient, which is composed of hydrogen production power consumption and entire system internal consumption. The hydrogen production power consumption accounts for a large proportion in the idle power. The power consumption is different under different working modes (cold start and hot standby), different environmental temperatures and different hydrogen output. The power consumption is generally the real-time power consumption. The internal consumption of the system generally accounts for a small proportion. The load power consumption is the real-time power consumption of the user's power consumption equipment; Figure 1 In the specification, the dashed line connecting the lithium battery and the net output power refers to that the net output power of the fuel cell is surplus to charge and maintain the lithium battery. The dashed line connecting the lithium battery and the load power consumption refers to that the lithium battery is discharged to supplement when the net output power of the fuel cell is insufficient to support the power consumption demand.

[0046] Specifically, as shown in Figure 2 ,

[0047] X0: real-time power consumption of the load;

[0048] X1: 1 / 4 of maximum load power consumption

[0049] X2: 2 / 4 of maximum load power consumption

[0050] X3: 3 / 4 of maximum load power consumption

[0051] X4: 4 / 4 of maximum load power consumption

[0052] Y: net output power of fuel cell

[0053] Z1: idle power = hydrogen production power consumption + system internal consumption

[0054] Z2: idle power + 1 / 4 of maximum load power consumption

[0055] Z3: idle power + 2 / 4 of maximum load power consumption

[0056] Z4: idle power + 3 / 4 of maximum load power consumption

[0057] Z5: idle power + 4 / 4 of maximum load power consumption

[0058] As shown in Figure 2 an embodiment of the method for controlling the net output power of a fuel cell, step S1, according to the size of the real-time power consumption of the load, determines the corresponding control level to enter, including:

[0059] Step S111, if the real-time power consumption of the load is greater than or equal to 0 and less than 1 / 4 of the maximum load power consumption, then it is determined to enter the corresponding first control level.

[0060] Step S2, based on the entered control level and the size of the lithium battery power, determine the net output power of the fuel cell, including:

[0061] Step S211, under the first control level, if the lithium battery power is greater than or equal to a first preset threshold, then the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption.

[0062] As shown in Figure 2 an embodiment of the method for controlling the net output power of a fuel cell, step S2, based on the entered control level and the size of the lithium battery power, determine the net output power of the fuel cell, including:

[0063] Step S212, under the first control level, if the lithium battery power is less than or equal to a second preset threshold, then the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 1 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0064] As shown in Figure 2As shown, in one embodiment of the fuel cell net output power control method of the present invention, step S1, determining the corresponding control level based on the real-time power consumption of the load, includes:

[0065] Step S121: If the real-time power consumption of the load is greater than or equal to 1 / 4 of the maximum load power consumption and less than 2 / 4 of the maximum load power consumption, then it is determined to enter the corresponding second control level.

[0066] Step S2, based on the incoming control level and the capacity of the lithium battery, determines the net output power of the fuel cell, including:

[0067] Step S221: Under the second control level, if the lithium battery charge is greater than or equal to the first preset threshold, then the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption plus 1 / 4 of the maximum load power consumption.

[0068] like Figure 2 As shown, in one embodiment of the fuel cell net output power control method of the present invention, step S2, determining the fuel cell net output power based on the entered control level and the amount of lithium battery charge, includes:

[0069] Step S222: Under the second control level, if the lithium battery charge is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 2 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0070] like Figure 2 As shown, in one embodiment of the fuel cell net output power control method of the present invention, step S1, determining the corresponding control level based on the real-time power consumption of the load, includes:

[0071] Step S131: If the real-time power consumption of the load is greater than or equal to 2 / 4 of the maximum load power consumption and less than 3 / 4 of the maximum load power consumption, then determine to enter the corresponding third control level.

[0072] Step S2, based on the incoming control level and the capacity of the lithium battery, determines the net output power of the fuel cell, including:

[0073] In step S231, under the third control level, if the lithium battery charge is greater than or equal to the first preset threshold, then the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption plus 2 / 4 of the maximum load power consumption.

[0074] like Figure 2 As shown, in one embodiment of the fuel cell net output power control method of the present invention, step S2, determining the fuel cell net output power based on the entered control level and the amount of lithium battery charge, includes:

[0075] In step S232, under the third control level, if the lithium battery charge is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 3 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0076] like Figure 2 As shown, in one embodiment of the fuel cell net output power control method of the present invention, step S1, determining the corresponding control level based on the real-time power consumption of the load, includes:

[0077] Step S141: If the real-time power consumption of the load is greater than or equal to 3 / 4 of the maximum load power consumption and less than or equal to 4 / 4 of the maximum load power consumption, then it is determined to enter the corresponding fourth control level.

[0078] Step S2, based on the incoming control level and the capacity of the lithium battery, determines the net output power of the fuel cell, including:

[0079] In step S241, under the fourth control level, if the lithium battery charge is greater than or equal to the first preset threshold, then the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption plus 3 / 4 of the maximum load power consumption.

[0080] like Figure 2 As shown, in one embodiment of the fuel cell net output power control method of the present invention, step S2, determining the fuel cell net output power based on the entered control level and the amount of lithium battery charge, includes:

[0081] In step S242, under the fourth control level, if the lithium battery charge is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 4 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

[0082] like Figure 2 As shown, in one embodiment of the fuel cell net output power control method of the present invention, the first preset threshold is 80% and the second preset threshold is 30%.

[0083] In summary, this invention, during power generation, adjusts the control level in real time according to the load size, with fuel cell power generation as the primary method and lithium battery power supply as a secondary method. Figure 2 It can be seen that the load is subdivided into four levels, each corresponding to an equal load, meaning that each level is one-quarter higher than the previous level. From left to right, the load ranges from 0 to the maximum load. The net output power of the fuel cell is not only related to the load size, but also to the lithium battery capacity and hydrogen production capacity. The three factors complement each other.

[0084] Firstly, the application enters different control levels according to the load size, and then sets the net output power of the fuel cell according to the size of the lithium battery power, when the lithium battery SOC is greater than or equal to 80%, the net output power of the fuel cell is set to be lower than the sum of the load and the idle power, and the insufficient part is supplemented by the lithium battery, when the lithium battery consumption is less than 30% SOC, the net output power of the fuel cell is set to be higher than the sum of the load and the idle power, and the excess part is charged to the lithium battery, and each level is the same, which indirectly restricts the charging current of the lithium battery, so that the charging current is not greater than the maximum allowed charging current of the lithium battery, because when the charging current is greater than 1.2 times the maximum allowed charging current, the lithium battery enters a self-protection state and can only be restored by powering off at low voltage, thereby affecting the normal use of the lithium battery.

[0085] The ambient temperature has a great influence on the charging and discharging current of the lithium battery, especially the charging part, so it is necessary to ensure that the working environment temperature of the lithium battery is within a suitable temperature range, according to Figure 3 The continuous charging limit table is used from the economic and practical point of view that the working temperature range is 5 to 45 degrees Celsius, Figure 2 The design parameters are based on the minimum environmental temperature of 5 degrees, the SOC is not higher than 80%, and the design load is 70KW. The minimum charging current limit of the lithium battery is 0.2C (40A) when the environmental temperature is 5 degrees and the SOC is not higher than 80%. The load is divided into four parts to meet the load power consumption while considering the battery charging current limit less than 0.2C.

[0086] When the power load exceeds the maximum design load, the fault state processing is entered, Figure 2 No description.

[0087] Each embodiment in the specification is described in a progressive manner, and each embodiment focuses on the difference from other embodiments. The same and similar parts between each embodiment can be referred to each other.

[0088] The skilled person can further realize that the units and algorithm steps of each example described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of the two. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of each example have been described in the above description. Whether the functions are executed in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the application.

[0089] It will be apparent to those skilled in the art that various modifications and variations can be made to the present application without departing from the spirit or scope of the application. Thus, it is intended that the present application cover modifications and variations of this application provided they come within the scope of the appended claims and their equivalents.

Claims

1. A method for controlling the net output power of a fuel cell, characterized in that, include: The appropriate control level is determined based on the real-time power consumption of the load. The net output power of the fuel cell is determined based on the control level of the input and the capacity of the lithium battery. The appropriate control level is determined based on the real-time power consumption of the load, including: If the real-time power consumption of the load is greater than or equal to 0 and less than 1 / 4 of the maximum load power consumption, then it is determined to enter the corresponding first control level; The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the first control level, if the lithium battery charge is greater than or equal to the first preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption. The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the first control level, if the lithium battery charge is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 1 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold. The appropriate control level is determined based on the real-time power consumption of the load, including: If the real-time load power consumption is greater than or equal to 1 / 4 of the maximum load power consumption and less than 2 / 4 of the maximum load power consumption, then it is determined to enter the corresponding second control level; The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the second control level, if the lithium battery charge is greater than or equal to the first preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 1 / 4 of the maximum load power consumption. The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the second control level, if the lithium battery charge is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 2 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold. The appropriate control level is determined based on the real-time power consumption of the load, including: If the real-time load power consumption is greater than or equal to 2 / 4 of the maximum load power consumption and less than 3 / 4 of the maximum load power consumption, then it is determined to enter the corresponding third control level. The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the third control level, if the lithium battery charge is greater than or equal to the first preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 2 / 4 of the maximum load power consumption. The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the third control level, if the lithium battery charge is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 3 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold. The appropriate control level is determined based on the real-time power consumption of the load, including: If the real-time load power consumption is greater than or equal to 3 / 4 of the maximum load power consumption and less than or equal to 4 / 4 of the maximum load power consumption, then it is determined to enter the corresponding fourth control level. The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the fourth control level, if the lithium battery charge is greater than or equal to the first preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 3 / 4 of the maximum load power consumption. The net output power of the fuel cell is determined based on the access control level and the capacity of the lithium battery, including: Under the fourth control level, if the lithium battery charge is less than or equal to the second preset threshold, the net output power of the fuel cell is equal to the hydrogen production power consumption plus the system internal consumption and 4 / 4 of the maximum load power consumption, wherein the second preset threshold is less than the first preset threshold.

2. The method for controlling the net output power of a fuel cell as described in any one of claims 1, characterized in that, The first preset threshold is 80%, and the second preset threshold is 30%.

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