Simulink-based fuel cell hybrid power system and modeling method

Abstract

The application provides a Simulink-based fuel cell hybrid power system and a modeling method, wherein in the system: an energy management strategy module acquires a ship demand power and distributes the ship demand power into a fuel cell demand power and a lithium battery demand power; a fuel cell module acquires the fuel cell demand power and calculates a fuel cell output power; a lithium battery charging and discharging module acquires the lithium battery demand power and calculates a lithium battery output power; an input end of a one-way DC / DC step-up converter module is connected with the fuel cell module, an output end is connected with a DC bus, and the one-way DC / DC step-up converter module is used for increasing the fuel cell side voltage to a DC bus demand voltage according to the fuel cell output power; an input end of a bidirectional DC / DC converter module is connected with the lithium battery charging and discharging module, an output end is connected with the DC bus, and the bidirectional DC / DC converter module is used for increasing the lithium battery voltage to the DC bus demand voltage according to the lithium battery output power; and a hydrogen consumption module is used for calculating a hydrogen consumption amount of the fuel cell according to the fuel cell output power.

Description

Technical Field

[0001] This invention relates to the field of marine technology, and more particularly to a Simulink-based fuel cell hybrid power system and modeling method. Background Technology

[0002] In recent years, clean, low-carbon, safe, and efficient transportation has gradually become mainstream. In the green shipping sector, new energy sources are being increasingly applied to the power systems of commercial ships. Traditional new energy sources such as solar and wind power are difficult to apply to ships due to their intermittency and limited power-to-volume ratio. Pure electric ships are currently widely used in various small and medium-sized commercial vessels, but their development prospects are limited due to the limited energy density of their batteries, poor range, and insufficient safety. Hydrogen fuel cells, with their high energy density, zero carbon emissions, and high efficiency, are highly suitable for use in new energy ship power systems. Currently, various countries, including my country, have launched research and development programs for hydrogen-powered ships, and a few have already been applied to commercial vessels.

[0003] As a future environmental strategy, we aim to reduce energy consumption and decrease CO2 and SO2 emissions. x NO x With PM emissions as the target, there are many ways to reduce pollution and emissions from ships, among which the best method is to utilize alternative energy sources. Currently, many types of energy can be easily applied to ships, such as liquefied natural gas, fuel cells, solar energy, wind energy, and high-capacity batteries, to reduce ship emissions. Power technologies are becoming increasingly mature, and it is only a matter of time before they replace the traditional single diesel engine propulsion. Today, my country is also strongly supporting research on hybrid power technology.

[0004] To fundamentally solve the problem of marine pollution from ships, the solution lies in improving ship propulsion systems or using clean energy sources as fuel. Therefore, a hybrid power propulsion system is adopted to address ship power and electricity usage issues, and most importantly, achieve energy conservation and emission reduction, while also providing more options for ship propulsion. Thus, a hybrid power system represents a feasible implementation method for evolving from a single system to a green energy propulsion system.

[0005] Therefore, green and energy-saving development in the shipbuilding industry has become a recognized goal. This development primarily focuses on several directions: hybrid-powered ships, pure electric ships, and clean energy ships such as solar and wind-powered ships. Due to limitations in clean energy technology, the application of purely clean energy ships is very rare. Furthermore, the range of pure electric ships remains questionable due to limitations in battery technology. In other words, the transition from internal combustion engines to zero-emission energy in ships requires a transitional product to support the arrival of stable and reliable clean energy technologies. Hybrid-powered ships are undoubtedly an ideal choice for this transitional product. Hybrid systems are widely used in automobiles, but compared to automobiles, ships have higher emissions per unit, yet the application of hybrid systems in ships is still limited to certain specialized vessels. This is related to the specific sailing conditions of ships. Compared to the automotive industry, the sailing conditions of ships are more unique, making it impossible to equip ships with standardized hybrid systems like automobiles.

[0006] The design of a marine hybrid power system must begin with the ship's inherent characteristics, obtaining its resistance characteristics. Then, based on the ship's operational requirements, the diesel engine, electric motor, battery, transmission system, and propulsion unit within the hybrid power system must be matched and selected. After determining the hardware configuration of the hybrid power system, a power distribution control strategy must be designed according to the ship's operational needs. For different types, models, and purposes of ships, the resistance characteristics and operational requirements vary significantly; therefore, a unique hybrid power system must be designed for each ship. The matching and selection of a marine hybrid power system shares many similarities with the matching and selection of conventional power systems; both are crucial parts of ship design. A good selection can not only meet various navigation requirements but also significantly reduce production and operating costs. As a power system characterized by energy conservation and emission reduction, the hybrid power system places even greater emphasis on saving operating costs. The key to matching and selecting a hybrid power system lies in the ship's resistance characteristics and the optimal coordination between two or more power sources. Furthermore, energy conservation and emission reduction in hybrid-powered ships cannot be achieved solely through matching and selection. Energy conservation and emission reduction rely on the coordinated operation of the diesel engine, battery, and electric motor, ensuring that both the diesel engine and battery operate within their relatively high efficiency ranges. Maintaining these high-efficiency operating ranges requires specific power distribution control strategies. Therefore, power distribution control strategies for hybrid power systems are a key focus of hybrid power system research.

[0007] A review of existing technologies revealed that some only analyzed the hydrogen consumption of hybrid-powered ships, proposing different energy management strategies to improve hydrogen utilization and effectively avoid resource waste. However, they did not integrate this with actual ship operating conditions, failing to effectively compare actual and ideal operating conditions. Therefore, this type of patent's hybrid power system only controls the energy source, with limited consideration for actual operating conditions. Summary of the Invention

[0008] To address the aforementioned technical problems, this invention provides a Simulink-based fuel cell hybrid power system. This invention designs different energy management strategies to simulate the power distribution between hydrogen fuel cells and lithium batteries on a ship under various operating conditions. Based on simulations of the ship's start-up, acceleration, deceleration, and shutdown processes, the changes in load power are analyzed, and appropriate energy routing strategies are selected, effectively saving energy and avoiding resource waste.

[0009] The technical means employed in this invention are as follows:

[0010] A Simulink-based fuel cell hybrid power system includes: an energy management strategy module, a fuel cell module, a lithium battery charging and discharging module, a unidirectional DC / DC boost converter module, a bidirectional DC / DC converter module, and a hydrogen consumption module, wherein:

[0011] The energy management strategy module is connected to the fuel cell module and the lithium battery charging and discharging module. It is used to obtain the ship's power demand and allocate the ship's power demand into the fuel cell power demand and the lithium battery power demand.

[0012] The fuel cell module is used to obtain the power demand of the fuel cell and calculate the output power of the fuel cell based on the power demand.

[0013] The lithium battery charging and discharging module is used to obtain the power demand of the lithium battery and calculate the output power of the lithium battery based on the power demand.

[0014] The unidirectional DC / DC boost converter module has its input end connected to the fuel cell module and its output end connected to the DC bus. It is used to boost the voltage on the fuel cell side to the required voltage of the DC bus according to the output power of the fuel cell.

[0015] The bidirectional DC / DC converter module has an input end connected to the lithium battery charging and discharging module and an output end connected to the DC bus, and is used to boost the lithium battery voltage to the required voltage of the DC bus according to the lithium battery output power.

[0016] The hydrogen consumption module is connected to the fuel cell module and is used to calculate the hydrogen consumption of the fuel cell based on the fuel cell's output power.

[0017] Furthermore, the fuel cell module includes: an electrically connected Nernst voltage module, an activation polarization voltage module, a concentration voltage module, and an ohmic polarization voltage module, wherein:

[0018] The Nernst voltage module is used to calculate the Nernst voltage E. Nernst The calculation formula is as follows:

[0019]

[0020] In the above formula, T is the internal operating temperature of the fuel cell, F is the Faraday constant, and R is the universal ideal gas constant P. H2 and P o2 These represent the partial pressures of hydrogen and oxygen, respectively.

[0021] The activation polarization voltage module is used to calculate the activation polarization voltage U. act The calculation formula is as follows:

[0022]

[0023] In the above formula, α is the conversion factor, i is the actual current density, and i0 is the exchange current density;

[0024] The concentration voltage module is used to calculate the concentration polarization voltage U. con The calculation formula is as follows:

[0025]

[0026] In the above formula, B is a constant, and J max J represents the maximum current density, and J represents the operating load of the fuel cell.

[0027] The ohmic polarization voltage module is used to calculate the ohmic polarization voltage U. ohm The calculation formula is as follows:

[0028] U ohm =IR ohm =I(R) m +R c )

[0029] In the above formula, I represents the output current of the fuel cell, and R... m R is the equivalent resistance of the proton exchange membrane. c This refers to the membrane resistance parameter.

[0030] Furthermore, the lithium battery charging and discharging module includes: an electrically connected variable resistance equivalent module and a power judgment module, wherein:

[0031] The variable resistor equivalent module is used to conveniently obtain the power required by the lithium battery;

[0032] The power determination module is used to determine the output power of the lithium battery based on its power demand and to calculate the lithium battery capacity using the following formula:

[0033]

[0034]

[0035]

[0036] In the above formula, Q0 is the initial capacity of the lithium battery, Q max For the maximum capacity of lithium batteries, i a E0 is the lithium battery current, E0 is the constant voltage of the lithium battery, K is the polarization constant, and i * Here, i represents the low-frequency dynamic current, and i represents the battery current. t To extract capacity, Q is the maximum battery capacity, A is the exponential voltage, and B is the exponential capacity.

[0037] Furthermore, the energy management strategy module allocates the ship's power demand into fuel cell power demand and lithium battery power demand based on stateflow, specifically including:

[0038] When the SOC of the battery pack is less than the minimum setting of 45%, the system switches to single power source propulsion mode. At this time, regardless of the power demand, the fuel cell alone undertakes the ship's operating load and charges the battery pack.

[0039] When the SOC of the battery pack is greater than the set limit of 45% but less than 70%, the system allocates energy according to the power demand. If the power demand of the ship is low, the fuel cell alone undertakes the system power demand and charges the battery. If the power demand of the ship is high, the fuel cell and the battery share the system power demand, but the battery only undertakes a small part of the power.

[0040] When the SOC of the battery pack is greater than 70%, the system operates in hybrid propulsion mode, and the power required by the ship will be shared by the fuel cell and the battery.

[0041] Furthermore, the hydrogen consumption module calculates the hydrogen consumption of the fuel cell based on the fuel cell's output power, using the following formula:

[0042]

[0043] Among them, W fc p represents hydrogen consumption. fc For the output power of the fuel cell, η fc For fuel cell efficiency.

[0044] This invention also provides a Simulink-based modeling method for hybrid power ships, implemented based on the aforementioned fuel cell hybrid power system, comprising:

[0045] S1. Establish a fuel cell model as follows:

[0046]

[0047]

[0048] U ohm =IR ohm =I(R) m +R c )

[0049]

[0050] In the above formula, E fc E is the output voltage of the fuel cell. Nernst U is the Nernst voltage. act To activate the polarization voltage, U ohm U is the ohmic polarization voltage. con The concentration polarization voltage is T; the internal operating temperature of the fuel cell is T; F is the Faraday constant; and R is the universal ideal gas constant P. H2 and P o2 These represent the partial pressures of hydrogen and oxygen, respectively; α is the conversion factor, i is the actual current density, i0 is the exchange current density; I is the output current of the fuel cell, and R... m R is the equivalent resistance of the proton exchange membrane. c Here, B is the membrane resistance parameter; J is a constant. max J represents the maximum current density, and J represents the operating load of the fuel cell.

[0051] S2. Establish a lithium battery model as follows:

[0052]

[0053]

[0054]

[0055] In the above formula, Q0 is the initial capacity of the lithium battery, Q max For the maximum capacity of lithium batteries, i a E0 is the lithium battery current, E0 is the constant voltage of the lithium battery, K is the polarization constant, and i * Here, i represents the low-frequency dynamic current, and i represents the battery current. t To extract capacity, Q is the maximum battery capacity, A is the exponential voltage, and B is the exponential capacity;

[0056] S3. Establish a hydrogen consumption module as follows:

[0057]

[0058] Among them, W fc p represents hydrogen consumption. fc For the output power of the fuel cell, η fc For fuel cell efficiency;

[0059] S4. Design an energy management strategy to simulate the power distribution between hydrogen fuel cells and lithium batteries under various operating conditions of the ship, and analyze the changes in load power based on the simulation of the ship's start-up, acceleration, deceleration and shutdown conditions, and select an appropriate energy pipeline strategy.

[0060] Furthermore, in step S4, based on the SOC threshold of the power battery, the switching rules of the fuel cell are determined, and according to different driving conditions, the fuel cell ship is divided into power battery-only drive mode, dual-power-supply-drive mode, cruise charging mode, and regenerative braking mode, specifically including:

[0061] When the SOC of the battery pack is less than the minimum setting of 45%, the system switches to single power source propulsion mode. At this time, regardless of the power demand, the fuel cell alone undertakes the ship's operating load and charges the battery pack.

[0062] When the SOC of the battery pack is greater than the set limit of 45% but less than 70%, the system allocates energy according to the power demand. If the power demand of the ship is low, the fuel cell alone undertakes the system power demand and charges the battery. If the power demand of the ship is high, the fuel cell and the battery share the system power demand, but the battery only undertakes a small part of the power.

[0063] When the SOC of the battery pack is greater than 70%, the system operates in hybrid propulsion mode, and the power required by the ship will be shared by the fuel cell and the battery.

[0064] Compared with the prior art, the present invention has the following advantages:

[0065] 1. The fuel cell hybrid power system based on Simulink provided by this invention can be applied to all operating conditions of ships, and finally simulates the power distribution results of each power source of the ship. The results are highly accurate, saving time and costs. In practical applications, the prediction of power can also improve the safety of actual ship operation.

[0066] 2. The Simulink-based fuel cell hybrid power system provided by this invention simulates the power distribution between hydrogen fuel cells and lithium batteries under various operating conditions on a ship by designing different energy management strategies. Based on simulations of the ship's start-up, acceleration, deceleration, and shutdown conditions, the system analyzes changes in load power and selects appropriate energy routing strategies, effectively saving energy and avoiding resource waste.

[0067] 3. The Simulink-based fuel cell hybrid power system provided by this invention not only effectively allocates ship power, but also allows the energy pipeline strategy module to monitor changes in the state of charge (SOC) of the power battery in real time, ensuring the safety of the system.

[0068] Based on the above reasons, this invention can be widely applied in fields such as shipbuilding. Attached Figure Description

[0069] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0070] Figure 1 This is a block diagram of the overall system structure of the present invention.

[0071] Figure 2 This is a schematic diagram of the fuel cell module of the present invention.

[0072] Figure 3 This is a schematic diagram of the lithium battery charging and discharging module of the present invention.

[0073] Figure 4 This is a schematic diagram of the energy management strategy module of the present invention.

[0074] Figure 5 This is a schematic diagram of the bidirectional DC / DC converter module of the present invention.

[0075] Figure 6 This is a schematic diagram of the unidirectional DC / DC boost converter module of the present invention.

[0076] Figure 7 A diagram showing the change in ship power provided for an embodiment of the present invention.

[0077] Figure 8 A power diagram of a fuel cell provided for an embodiment of the present invention.

[0078] Figure 9 The lithium battery power diagram provided for an embodiment of the present invention.

[0079] Figure 10 The SOC variation diagram provided for an embodiment of the present invention. Detailed Implementation

[0080] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0081] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0082] like Figure 1 As shown, this invention provides a Simulink-based fuel cell hybrid power system, comprising: an energy management strategy module, a fuel cell module, a lithium battery charging and discharging module, a unidirectional DC / DC boost converter module, a bidirectional DC / DC converter module, and a hydrogen consumption module, wherein:

[0083] The energy management strategy module is connected to the fuel cell module and the lithium battery charging and discharging module. It is used to obtain the ship's power demand and allocate the ship's power demand into the fuel cell power demand and the lithium battery power demand.

[0084] The fuel cell module is used to obtain the power demand of the fuel cell and calculate the output power of the fuel cell based on the power demand.

[0085] The lithium battery charging and discharging module is used to obtain the power demand of the lithium battery and calculate the output power of the lithium battery based on the power demand.

[0086] The unidirectional DC / DC boost converter module, with its input connected to the fuel cell module and its output connected to the DC bus, is used to boost the fuel cell-side voltage to the required DC bus voltage based on the fuel cell's output power. Figure 6 The diagram shown is a schematic of a unidirectional DC / DC boost converter module.

[0087] The bidirectional DC / DC converter module has its input connected to a lithium battery charging / discharging module and its output connected to a DC bus. It is used to boost the lithium battery voltage to the required DC bus voltage based on the lithium battery's output power. Figure 5 The diagram shown is a schematic of a bidirectional DC / DC converter module.

[0088] The hydrogen consumption module is connected to the fuel cell module and is used to calculate the hydrogen consumption of the fuel cell based on the fuel cell's output power.

[0089] In specific implementation, as a preferred embodiment of the present invention, such as Figure 2 As shown, the fuel cell module includes: an electrically connected Nernst voltage module, an activation polarization voltage module, a concentration voltage module, and an ohmic polarization voltage module, wherein:

[0090] The Nernst voltage module is used to calculate the Nernst voltage E. Nernst The calculation formula is as follows:

[0091]

[0092] In the above formula, T is the internal operating temperature of the fuel cell, F is the Faraday constant, and R is the universal ideal gas constant P. H2 and P o2 These represent the partial pressures of hydrogen and oxygen, respectively.

[0093] The activation polarization voltage module is used to calculate the activation polarization voltage U. act The calculation formula is as follows:

[0094]

[0095] In the above formula, α is the conversion factor, i is the actual current density, and i0 is the exchange current density;

[0096] The concentration voltage module is used to calculate the concentration polarization voltage U. con The calculation formula is as follows:

[0097]

[0098] In the above formula, B is a constant, and J max J represents the maximum current density, and J represents the operating load of the fuel cell.

[0099] The ohmic polarization voltage module is used to calculate the ohmic polarization voltage U. ohm The calculation formula is as follows:

[0100] U ohm =IR ohm =I(R) m +R c )

[0101] In the above formula, I represents the output current of the fuel cell, and R... m R is the equivalent resistance of the proton exchange membrane. c This refers to the membrane resistance parameter.

[0102] In specific implementation, as a preferred embodiment of the present invention, such as Figure 3 As shown, the lithium battery charging and discharging module includes: an electrically connected variable resistance equivalent module and a power judgment module, wherein:

[0103] The variable resistor equivalent module is used to conveniently obtain the power required by the lithium battery;

[0104] The power determination module is used to determine the output power of the lithium battery based on its power demand and to calculate the lithium battery capacity using the following formula:

[0105]

[0106]

[0107]

[0108] In the above formula, Q0 is the initial capacity of the lithium battery, Q max For the maximum capacity of lithium batteries, i a E0 is the lithium battery current, E0 is the constant voltage of the lithium battery, K is the polarization constant, and i * Here, i represents the low-frequency dynamic current, and i represents the battery current. t To extract capacity, Q is the maximum battery capacity, A is the exponential voltage, and B is the exponential capacity.

[0109] In specific implementation, as a preferred embodiment of the present invention, such as Figure 4 As shown, the energy management strategy module allocates the ship's power demand into fuel cell power demand and lithium battery power demand based on Stateflow, specifically including:

[0110] When the SOC of the battery pack is less than the minimum setting of 45%, the system switches to single power source propulsion mode. At this time, regardless of the power demand, the fuel cell alone undertakes the ship's operating load and charges the battery pack.

[0111] When the SOC of the battery pack is greater than the set limit of 45% but less than 70%, the system allocates energy according to the power demand. If the power demand of the ship is low, the fuel cell alone undertakes the system power demand and charges the battery. If the power demand of the ship is high, the fuel cell and the battery share the system power demand, but the battery only undertakes a small part of the power.

[0112] When the SOC of the battery pack is greater than 70%, the system operates in hybrid propulsion mode, and the power required by the ship will be shared by the fuel cell and the battery.

[0113] In a preferred embodiment of the present invention, the hydrogen consumption module calculates the hydrogen consumption of the fuel cell based on the fuel cell output power, using the following formula:

[0114]

[0115] Among them, W fcp represents hydrogen consumption. fc For the output power of the fuel cell, η fc For fuel cell efficiency.

[0116] This invention also provides a Simulink-based modeling method for hybrid power ships, which is implemented based on the aforementioned fuel cell hybrid power system and includes:

[0117] S1. Establish a fuel cell model as follows:

[0118]

[0119]

[0120] U ohm =IR ohm =I(R) m +R c )

[0121]

[0122] In the above formula, E fc E is the output voltage of the fuel cell. Nernst U is the Nernst voltage. act To activate the polarization voltage, U ohm U is the ohmic polarization voltage. con The concentration polarization voltage is T; the internal operating temperature of the fuel cell is T; F is the Faraday constant; and R is the universal ideal gas constant P. H2 and P o2 These represent the partial pressures of hydrogen and oxygen, respectively; α is the conversion factor, i is the actual current density, i0 is the exchange current density; I is the output current of the fuel cell, and R... m R is the equivalent resistance of the proton exchange membrane. c Here, B is the membrane resistance parameter; J is a constant. max J represents the maximum current density, and J represents the operating load of the fuel cell.

[0123] S2. Establish a lithium battery model as follows:

[0124]

[0125]

[0126]

[0127] In the above formula, Q0 is the initial capacity of the lithium battery, Q max For the maximum capacity of lithium batteries, i a E0 is the lithium battery current, E0 is the constant voltage of the lithium battery, K is the polarization constant, and i *Here, i represents the low-frequency dynamic current, and i represents the battery current. t To extract capacity, Q is the maximum battery capacity, A is the exponential voltage, and B is the exponential capacity;

[0128] S3. Establish a hydrogen consumption module as follows:

[0129]

[0130] Among them, W fc p represents hydrogen consumption. fc For the output power of the fuel cell, η fc For fuel cell efficiency;

[0131] S4. Design an energy management strategy to simulate the power distribution between hydrogen fuel cells and lithium batteries under various operating conditions on the ship. Based on the simulation of the ship's start-up, acceleration, deceleration, and shutdown conditions, analyze the changes in load power and select an appropriate energy pipeline strategy. In step S4, based on the power battery's SOC threshold, determine the switching rules for the fuel cell. According to different operating conditions, the fuel cell ship is divided into power battery-only drive mode, dual-power-supply-drive mode, cruise charging mode, and regenerative braking mode, specifically including:

[0132] When the SOC of the battery pack is less than the minimum setting of 45%, the system switches to single power source propulsion mode. At this time, regardless of the power demand, the fuel cell alone undertakes the ship's operating load and charges the battery pack.

[0133] When the SOC of the battery pack is greater than the set limit of 45% but less than 70%, the system allocates energy according to the power demand. If the power demand of the ship is low, the fuel cell alone undertakes the system power demand and charges the battery. If the power demand of the ship is high, the fuel cell and the battery share the system power demand, but the battery only undertakes a small part of the power.

[0134] When the SOC of the battery pack is greater than 70%, the system operates in hybrid propulsion mode, and the power required by the ship will be shared by the fuel cell and the battery.

[0135] Example

[0136] Different operating conditions of the ship during operation are retrieved as analog signals and input to the energy management strategy module. Based on the energy management strategy, the ship's required power is allocated to the fuel cell module and the lithium battery charging / discharging module. Upon receiving the analog input signals, the fuel cell module and the lithium battery charging / discharging module calculate the actual operating power and allocate it to the DC bus. After receiving the signal, the DC bus transmits the actual operating power as a new input signal to the energy management strategy module, thus achieving a closed loop. Figure 7-10The diagram shown illustrates the ship power variation, fuel cell power, lithium battery power, and SOC variation provided in this embodiment of the invention. Figure 7-10 As can be seen, by inputting the required power, the power of the fuel cell and the lithium battery can be obtained, making it convenient to select the appropriate number of fuel cells and lithium batteries. This invention's system can effectively save energy and avoid resource waste.

[0137] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A Simulink-based fuel cell hybrid power system, characterized in that, include: The module includes an energy management strategy module, a fuel cell module, a lithium battery charging and discharging module, a unidirectional DC / DC boost converter module, a bidirectional DC / DC converter module, and a hydrogen consumption module, among which: The energy management strategy module is connected to the fuel cell module and the lithium battery charging and discharging module. It is used to obtain the ship's power demand and allocate the ship's power demand into the fuel cell power demand and the lithium battery power demand. The fuel cell module, used to acquire the power demand of the fuel cell and calculate the output power of the fuel cell based on the power demand, includes: an electrically connected Nernst voltage module, an activation polarization voltage module, a concentration voltage module, and an ohmic polarization voltage module, wherein: The Nernst voltage module is used to calculate the Nernst voltage. The calculation formula is as follows: In the above formula, The internal temperature of the fuel cell during operation. It is Faraday's constant. The universal ideal gas constant and These represent the partial pressures of hydrogen and oxygen, respectively. The activation polarization voltage module is used to calculate the activation polarization voltage. The calculation formula is as follows: In the above formula, As a transformation factor, For actual current density, For exchange current density; The concentration voltage module is used to calculate the concentration polarization voltage. The calculation formula is as follows: In the above formula, It is a constant. For maximum current density, The load factor for fuel cell operation; The ohmic polarization voltage module is used to calculate the ohmic polarization voltage. The calculation formula is as follows: In the above formula, For the fuel cell to output current, This is the equivalent resistance of the proton exchange membrane. For membrane resistance parameters; The lithium battery charging and discharging module is used to obtain the power demand of the lithium battery and calculate the output power of the lithium battery based on the power demand. It includes an electrically connected variable resistance equivalent module and a power judgment module, wherein: The variable resistor equivalent module is used to conveniently obtain the power required by the lithium battery; The power determination module is used to determine the output power of the lithium battery based on its power demand and to calculate the lithium battery capacity using the following formula: In the above formula, This refers to the initial capacity of the lithium battery. This is the maximum capacity of the lithium battery. This is the current of the lithium battery. This is the constant voltage value of the lithium battery. It is the polarization constant. For low-frequency dynamic current, Battery current, For extraction capacity, For maximum battery capacity, It is an exponential voltage. For exponential capacity; The unidirectional DC / DC boost converter module has its input end connected to the fuel cell module and its output end connected to the DC bus. It is used to boost the voltage on the fuel cell side to the required voltage of the DC bus according to the output power of the fuel cell. The bidirectional DC / DC converter module has an input end connected to the lithium battery charging and discharging module and an output end connected to the DC bus, and is used to boost the lithium battery voltage to the required voltage of the DC bus according to the lithium battery output power. The hydrogen consumption module is connected to the fuel cell module and is used to calculate the hydrogen consumption of the fuel cell based on the fuel cell's output power.

2. The Simulink-based fuel cell hybrid power system according to claim 1, characterized in that, The energy management strategy module allocates the ship's power demand into fuel cell power demand and lithium battery power demand based on stateflow, specifically including: When the SOC of the battery pack is less than the minimum setting of 45%, the system switches to single power source propulsion mode. At this time, regardless of the power demand, the fuel cell alone undertakes the ship's operating load and charges the battery pack. When the SOC of the battery pack is greater than the set limit of 45% but less than 70%, the system allocates energy according to the power demand. If the power demand of the ship is low, the fuel cell alone undertakes the system power demand and charges the battery. If the power demand of the ship is high, the fuel cell and the battery share the system power demand, but the battery only undertakes a small part of the power. When the SOC of the battery pack is greater than 70%, the system operates in hybrid propulsion mode, and the power required by the ship will be shared by the fuel cell and the battery.

3. The Simulink-based fuel cell hybrid power system according to claim 1, characterized in that, The hydrogen consumption module calculates the hydrogen consumption of the fuel cell based on the fuel cell's output power, using the following formula: in, This refers to hydrogen consumption. For fuel cell output power, For fuel cell efficiency.

4. A modeling method for hybrid-powered ships based on Simulink, characterized in that, Based on any one of claims 1-3 above, the fuel cell hybrid power system includes: S1. Establish a fuel cell model as follows: In the above formula, This is the output voltage of the fuel cell. For Nernst voltage, To activate the polarization voltage, The ohmic polarization voltage. This is the concentration polarization voltage; The internal temperature of the fuel cell during operation. It is Faraday's constant. The universal ideal gas constant and These represent the partial pressures of hydrogen and oxygen, respectively. As a transformation factor, For actual current density, For exchange current density; For the fuel cell to output current, This is the equivalent resistance of the proton exchange membrane. For membrane resistance parameters; It is a constant. For maximum current density, The load factor for fuel cell operation; S2. Establish a lithium battery model as follows: In the above formula, This refers to the initial capacity of the lithium battery. This is the maximum capacity of the lithium battery. This is the current of the lithium battery. This is the constant voltage value of the lithium battery. It is the polarization constant. For low-frequency dynamic current, Battery current, For extraction capacity, For maximum battery capacity, It is an exponential voltage. For exponential capacity; S3. Establish the hydrogen consumption module as follows: in, This refers to hydrogen consumption. For fuel cell output power, For fuel cell efficiency; S4. Design an energy management strategy to simulate the power distribution between hydrogen fuel cells and lithium batteries under various operating conditions of the ship, and analyze the changes in load power based on the simulation of the ship's start-up, acceleration, deceleration and shutdown conditions, and select an appropriate energy pipeline strategy.

5. The modeling method for hybrid-powered ships based on Simulink according to claim 4, characterized in that, In step S4, based on the SOC threshold of the power battery, the switching rules of the fuel cell are determined. According to different driving conditions, the fuel cell ship is divided into power battery-only drive mode, dual-power-supply-drive mode, cruise charging mode, and regenerative braking mode, specifically including: When the SOC of the battery pack is less than the minimum setting of 45%, the system switches to single power source propulsion mode. At this time, regardless of the power demand, the fuel cell alone undertakes the ship's operating load and charges the battery pack. When the SOC of the battery pack is greater than the set limit of 45% but less than 70%, the system allocates energy according to the power demand. If the power demand of the ship is low, the fuel cell alone undertakes the system power demand and charges the battery. If the power demand of the ship is high, the fuel cell and the battery share the system power demand, but the battery only undertakes a small part of the power. When the SOC of the battery pack is greater than 70%, the system operates in hybrid propulsion mode, and the power required by the ship will be shared by the fuel cell and the battery.

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