Hydrogen fuel power system, control method, fuel cell controller and telescopic arm forklift

Abstract

The present invention discloses a hydrogen fuel power system for a telescopic forklift, a control method, a fuel cell controller, and a telescopic forklift. The hydrogen fuel power system includes a hydrogen fuel cell system and a lithium battery. When the telescopic forklift starts, it is powered solely by the lithium battery; after the hydrogen fuel cell system reaches the starting temperature, the current vehicle power demand and the lithium battery SOC are obtained; based on the current vehicle power demand and the lithium battery SOC, combined with the high-efficiency working range of the hydrogen fuel cell system and the SOC range of the lithium battery, the output power of the hydrogen fuel cell system and the lithium battery is adjusted in real time; when the telescopic forklift brakes, the lithium battery recovers the braking energy generated by the motor. The present invention combines lithium batteries and fuel cells, and by controlling the operating state and energy distribution of the vehicle, the lithium batteries and fuel cells operate in a high-efficiency range, which not only meets the power performance of the vehicle, but also improves the utilization efficiency of the lithium batteries and fuel cells and extends the service life of the fuel cells.

Description

Technical Field

[0001] The present invention relates to a hydrogen fuel power system for a telescopic forklift, a control method, a fuel cell controller and the telescopic forklift, and belongs to the field of power supply technology and power systems for vehicle auxiliary equipment. Background Art

[0002] my country's commercial vehicle industry has long faced challenges such as high energy consumption, severe environmental pollution, and low independent innovation capabilities. Therefore, new energy commercial vehicles have become a key development direction for the Chinese automotive industry. Hydrogen fuel cells are widely recognized as the preferred solution for heavy-duty telescopic forklifts with long driving ranges, high power requirements, and large vehicle sizes. Hydrogen fuel cells offer the advantages of high energy density and energy conversion efficiency, as well as a short refueling time, far less than that of lithium batteries. Therefore, the development and application of hydrogen fuel cells not only helps alleviate energy and environmental pressures, but also better meets practical application needs.

[0003] However, hydrogen generally exists in a flammable and explosive gaseous state, creating significant challenges in its storage and transportation. High-pressure hydrogen gas is a relatively mature method of hydrogen storage, currently the primary method for on-board hydrogen storage. This method, typically at 20 MPa, places high demands on the containers, leading to bottlenecks such as low hydrogen storage and transportation capacity and short transport distances, and the risk of gas leakage and explosion.

[0004] Furthermore, hydrogen fuel cells suffer from slow dynamic response and poor cold-start performance. When a fuel cell is the sole energy source for a vehicle, it's difficult to meet the vehicle's actual power requirements, and braking energy cannot be recovered. Therefore, an energy management strategy is needed to manage the vehicle's power requirements. This strategy coordinates the power output of each energy source based on its characteristics and current state, controlling each energy source to operate within its high-efficiency range. This ensures that the vehicle's power requirements are met while maximizing fuel economy and the durability of each energy source. Summary of the Invention

[0005] The purpose of the present invention is to overcome the deficiencies in the prior art and to provide a method for controlling a hydrogen fuel power system for a telescopic forklift, a fuel cell controller, a hydrogen fuel power system, and a telescopic forklift.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect, the present invention provides a method for controlling a hydrogen fuel power system for a telescopic forklift, wherein the hydrogen fuel power system includes a hydrogen fuel cell system and a lithium battery. The hydrogen fuel cell system and the lithium battery are used to power the electrical system of the telescopic forklift, and the hydrogen fuel cell system is also used to charge the lithium battery. The method includes:

[0008] When the telescopic forklift starts, it is powered solely by the lithium battery;

[0009] After the hydrogen fuel cell system reaches the starting temperature, obtain the current vehicle power demand and lithium battery SOC;

[0010] Based on the current vehicle power demand and lithium battery SOC, combined with the efficient working range of the hydrogen fuel cell system and the SOC range of the lithium battery, determine whether to start the hydrogen fuel cell system, and adjust the output power of the hydrogen fuel cell system and lithium battery in real time.

[0011] Furthermore, the method of determining whether to start the hydrogen fuel cell system and adjust the output power of the hydrogen fuel cell system and the lithium battery in real time based on the current vehicle power demand and the lithium battery SOC, combined with the efficient working range of the hydrogen fuel cell system and the SOC range of the lithium battery, includes:

[0012] If lithium battery SOC>SOC min The required power of the vehicle is less than the maximum working power P of the hydrogen fuel cell system in the efficient working range. fcmax , so that the output power of the hydrogen fuel cell system is the maximum working power P fcmax ;

[0013] If lithium battery SOC>SOC max , and the vehicle's required power is less than the minimum working power P in the efficient working range of the hydrogen fuel cell system fcmin , the hydrogen fuel cell system stops working, and the lithium battery output power is equal to the vehicle's required power; where SOC max The maximum remaining capacity in the lithium battery SOC range;

[0014] If the lithium battery SOC <SOC min , and the vehicle's required power is less than the maximum working power P in the efficient working range of the hydrogen fuel cell system fcmax , the hydrogen fuel cell system is turned on, assuming the power consumption of the entire vehicle, and at the same time charging the lithium battery with electricity, making its SOC tend to the expected value of the remaining power SOC*, and limiting the output power of the hydrogen fuel cell system to P fcmin and P fcmax Between; among which SOC min The lowest remaining power in the lithium battery SOC range;

[0015] If the lithium battery SOC max >SOC>SOC*, and the vehicle's required power P re Greater than the maximum operating power P in the efficient working range of the hydrogen fuel cell system fcmax The hydrogen fuel cell system and lithium battery jointly provide energy for the vehicle, while limiting the output power of the hydrogen fuel cell system to P fcmin and P fcmax between;

[0016] If the State of Charge (SOC) of the lithium battery min <SOC ≤ SOC*, and the vehicle demand power P re is greater than the maximum operating power P of the efficient operating range of the hydrogen fuel cell system fcmax , the output power of the hydrogen fuel cell system is the maximum operating power P fcmax , and the insufficient power is provided by the lithium battery.

[0017] Furthermore, the control method of the hydrogen fuel power system for a telescopic forklift also includes:

[0018] When the telescopic forklift brakes, if the telescopic forklift uses electric braking and the SOC of the lithium battery ≤ SOC max , the hydrogen fuel cell system is turned off, and the braking energy generated by the motor is recovered by the lithium battery, where SOC max is the highest remaining charge in the SOC range of the lithium battery.

[0019] Furthermore, the control method of the hydrogen fuel power system for a telescopic forklift also includes:

[0020] Analyze the vehicle demand power according to the working conditions of the telescopic forklift to obtain the time-domain diagram of the vehicle demand power, convert the time-domain diagram into a frequency-domain diagram, and perform frequency-domain analysis on the vehicle demand power according to the frequency-domain diagram;

[0021] According to the results of the frequency-domain analysis, use a low-pass filter to filter the vehicle demand power, and regard the low-frequency power demand as the demand power for the hydrogen fuel cell system, and transfer the high-frequency power demand to the lithium battery.

[0022] Furthermore, the step of using a low-pass filter to filter the vehicle demand power according to the results of the frequency-domain analysis includes:

[0023] According to the results of the frequency-domain analysis, use a low-pass filter with an adjustable cut-off frequency to filter the vehicle demand power.

[0024] Furthermore, the cut-off frequency of the low-pass filter is adjusted online through a fuzzy controller, including:

[0025] Input the vehicle demand power and the SOC of the lithium battery into the fuzzy controller;

[0026] The fuzzy controller outputs the cut-off frequency of the low-pass filter according to the vehicle demand power and the SOC of the lithium battery, combined with the pre-set judgment rules.

[0027] Furthermore, the step that the fuzzy controller outputs the cut-off frequency of the low-pass filter according to the vehicle demand power and the SOC of the lithium battery, combined with the pre-set judgment rules, includes:

[0028] When the lithium battery SOC is lower than the minimum SOC of the lithium battery SOC efficient working area and the vehicle demand power is greater than the minimum demand power of the telescopic arm forklift efficient working area, the cutoff frequency output by the fuzzy controller is greater than the cutoff frequency set by the low-pass filter;

[0029] When the lithium battery SOC is higher than the maximum SOC in the lithium battery SOC efficient working area and the vehicle demand power is less than the minimum demand power in the telescopic arm forklift efficient working area, the cutoff frequency output by the fuzzy controller is less than the cutoff frequency set by the low-pass filter.

[0030] In a second aspect, the present invention provides a fuel cell controller for a hydrogen fuel power system for a telescopic arm forklift, wherein the fuel cell controller is used to execute the aforementioned control method for the hydrogen fuel power system.

[0031] In the third aspect, the present invention provides a hydrogen fuel power system for a telescopic arm forklift, including a hydrogen fuel cell system, a lithium battery, a DC / DC module and the aforementioned fuel cell controller, the fuel cell controller is connected to the hydrogen fuel cell system, the output end of the hydrogen fuel cell system's stack is connected to the DC / DC module, the DC / DC module is connected to the lithium battery, and the DC / DC module and the lithium battery are both connected to the telescopic arm forklift's power system, wherein the DC / DC module is used to stabilize the output voltage of the hydrogen fuel cell system's stack, and charge the lithium battery and supply power to the telescopic arm forklift according to the control instructions issued by the fuel cell controller; the lithium battery is used to supply power to the telescopic arm forklift's power system according to the control instructions issued by the fuel cell controller, and meet the function of one-button power-on by the key.

[0032] Furthermore, the hydrogen fuel cell system uses solid-state hydrogen storage as a hydrogen source.

[0033] Furthermore, the hydrogen fuel power system for a telescopic arm forklift also includes: a vehicle controller, a battery management system, a motor controller and a gearbox. The vehicle controller is communicatively connected to the fuel cell controller, the battery management system, the motor controller and the gearbox via a CAN bus. The battery management system is connected to the lithium battery. The fuel cell controller is communicatively connected to the battery management system via a CAN bus. The vehicle controller collects relevant control signals from the driver and simultaneously receives status information fed back by the fuel cell controller, the battery management system, the motor controller and the gearbox. Through internal calculation and decision-making, it outputs control instructions to the controllers of each component via the CAN bus to enable the components to work in a coordinated manner.

[0034] In a fourth aspect, the present invention provides a telescopic forklift, comprising the aforementioned hydrogen fuel power system for the telescopic forklift.

[0035] Compared with the prior art, the present invention has the following beneficial technical effects:

[0036] By combining lithium batteries and fuel cells, the present invention can better adapt to the complex and changeable working conditions of telescopic boom forklifts. The addition of lithium batteries can compensate for the slow dynamic response of fuel cells. The power-following energy management strategy can flexibly cooperate with the fuel cell and make the fuel cell operate stably in a high-efficiency area. Braking energy recovery can recover braking energy, thereby improving the fuel economy of the entire vehicle.

[0037] The hydrogen storage device can achieve low-pressure, high-density hydrogen storage and high-purity hydrogen supply. It is reusable, safe, economical and has good adaptability.

[0038] Adding an adaptive low-pass filter to the power-following energy management strategy can reduce fluctuations in the fuel cell power demand during actual telescopic forklift operation, thereby improving the durability of the fuel cell.

[0039] Through the vehicle controller and fuel cell controller, the working status of each component of the vehicle can be coordinated so that they all operate in a relatively ideal area. While meeting the complex and changeable working conditions of the telescopic arm forklift, the overall operation of the vehicle can be kept in the best state, thereby significantly improving the vehicle's power, fuel economy and the service life of each component. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 This is a structural block diagram of a hydrogen fuel power system for a telescopic forklift provided in Example 1 of the present invention;

[0041] Figure 2 This is a flow chart of a control method for a hydrogen fuel power system for a telescopic forklift provided in the second embodiment of the present invention;

[0042] Figure 3 1 is a schematic diagram of the operation of an adaptive low-pass filter provided by the third embodiment of the present invention;

[0043] Figure 4 This is a schematic structural diagram of a hydrogen fuel power system for a telescopic forklift provided in a fifth embodiment of the present invention;

[0044] Figure 5 This is a schematic diagram of a telescopic forklift provided by Example 6 of the present invention;

[0045] Among them, 1 hydrogen fuel cell system; 2 motor controller; 3 drive motor; 4 gearbox. DETAILED DESCRIPTION

[0046] The present invention will be further described below in conjunction with specific examples. The following examples are only used to more clearly illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention.

[0047] Example 1:

[0048] like Figure 1 As shown, a hydrogen fuel power system for a telescopic arm forklift includes a hydrogen fuel cell system and a hydrogen fuel cell control system.

[0049] The hydrogen fuel cell system includes a hydrogen storage and supply system, a fuel cell stack, an air supply system, and a cooling water circulation system;

[0050] Hydrogen storage and supply system, used to provide hydrogen for hydrogen fuel power system;

[0051] Hydrogen and air undergo a chemical reaction in the fuel cell stack to generate electricity;

[0052] Air supply system, used to provide the oxygen required for the stack reaction in the hydrogen fuel cell;

[0053] The cooling water circulation system is used to control the thermal system of the entire hydrogen fuel power system, which can ensure that the hydrogen fuel power system operates within a suitable temperature range, thereby improving the efficiency of the hydrogen fuel power system.

[0054] Optionally, the hydrogen storage and supply system includes a hydrogen storage tank, a pressure reducing valve, a regulating valve, a check valve, a humidifier, a water separator, a hydrogen circulation pump and an exhaust gas discharge valve;

[0055] The hydrogen storage tank can store and release solid hydrogen. It is located at the rear of the forklift for easy refueling. The hydrogen storage tank is connected to the fuel cell stack through the air intake pipe, and the hydrogen storage tank can transport hydrogen to the fuel cell stack through the air intake pipe.

[0056] Specifically, hydrogen storage tanks can store solid hydrogen. Compared to high-pressure gaseous and liquid hydrogen storage, solid hydrogen storage has a higher storage capacity, does not require high-pressure or insulated containers, and poses no explosion hazard. Solid-state hydrogen storage materials primarily include hydrogen storage alloys, nanomaterials, and graphene materials. For example, solid-state hydrogen storage can be achieved through physical adsorption.

[0057] Telescopic forklifts are multifunctional lifting and handling equipment widely used in the construction and maintenance of ports, docks, mines, construction sites, and oil and gas pipelines. In addition to the standard forks, they also include buckets, clamps, and aerial work platforms. Solid-state hydrogen storage has a high storage capacity and is safer than high-pressure gaseous and liquid hydrogen storage. Using solid-state hydrogen as a hydrogen source for telescopic forklifts can meet a variety of operating conditions.

[0058] The pressure reducing valve and regulating valve reduce the outlet pressure of the hydrogen storage tank to the pressure required by the fuel cell stack through adjustment, and automatically keep the pressure of the gas delivered to the fuel cell stack stable.

[0059] The check valve has a flow direction to prevent hydrogen from flowing back into the hydrogen storage tank and causing danger.

[0060] The humidifier increases the wettability of the proton exchange membrane in the fuel cell stack, thereby increasing the conductivity of protons. The selection of the humidifier mainly considers its dew point approach temperature, flow resistance, temperature and pressure resistance, and maximum transmembrane pressure difference.

[0061] Liquid water is discharged from the fuel cell stack through the solenoid valve in the water separator, and the water vapor is recycled to the anode inlet of the fuel cell stack. The use of water separator gas effectively improves the system's hydrogen utilization rate, improves power generation efficiency, and reduces the impact of liquid water on fuel cell durability.

[0062] The hydrogen circulation pump is connected to one end of the exhaust pipe, and the fuel cell stack can recycle and reuse the hydrogen through the exhaust pipe, effectively improving the utilization rate of hydrogen.

[0063] The tail gas discharge valve is used to discharge the water vapor produced by the reaction.

[0064] Optionally, the air supply system includes an air compressor, an air radiator, a humidifying device, and a back pressure regulating valve.

[0065] The air compressor is installed on the air intake pipeline, and the air compressor can introduce more air into the fuel cell stack.

[0066] Since air compression increases the temperature of the air, the temperature of the air entering the fuel cell stack can be reduced by installing an air radiator.

[0067] The function of the humidifier is to humidify the air to improve the output performance of the fuel cell and improve the efficiency of the fuel cell.

[0068] The one-way valve of the back pressure regulating valve is used to prevent air backflow, create a good working environment for the air compressor, improve the working performance of the air compressor, and ensure the stability of the air flow of the air compressor.

[0069] Optionally, the cooling water circulation system includes a cooling water tank, a cooling water pump, a bypass valve, a radiator and a fan.

[0070] The cooling water tank is used to reduce the temperature of the liquid in the water circulation circuit;

[0071] The cooling water pump is used to accelerate the circulation speed of the liquid in the circulating water circuit;

[0072] The bypass valve is installed on the bypass pipe of the water inlet valve pipe section to fill water to balance the water pressure before and after the water inlet valve;

[0073] The radiator and the fan are used to reduce the temperature of the liquid in the outlet circulation water circuit.

[0074] The hydrogen fuel cell control system is used to realize online detection, real-time control and fault diagnosis of the hydrogen fuel cell system to ensure stable and reliable operation of the system.

[0075] Optionally, the hydrogen fuel cell control system includes a fuel cell controller, a DC / DC module, a lithium battery and an on-board charger.

[0076] The fuel cell controller is used for gas path management, water and heat management, electrical management, communication transmission and fault diagnosis. The fuel cell controller can adjust the output power of the lithium battery or battery stack according to the load of the entire vehicle, thereby achieving optimal distribution of electrical energy in the power system.

[0077] The DC / DC module is used to stabilize the output voltage of the fuel cell stack and, according to instructions from the fuel cell controller, to charge the lithium battery and power the motor controller and electrical system components in the telescopic forklift.

[0078] The lithium battery is used to power the motor controller and electrical system components in the telescopic forklift according to the instructions issued by the fuel cell controller, and to meet the function of one-touch power-on by the key.

[0079] Specifically, key-activated power-on means that when the key is activated, the relay in the lithium battery is energized, the DC / DC module is powered on, and the hydrogen fuel cell control system controls the discharge of the lithium battery and / or hydrogen fuel cell, putting the entire vehicle into a standby state. This one-touch key-activated power-on method makes it easier to power on the telehandler and operate it more simply.

[0080] The on-board charger is used to charge and heat the lithium battery, solving the problem that the hydrogen fuel power system cannot start when hydrogen is not added in time, the lithium battery is out of power or the temperature is too low.

[0081] Optionally, the hydrogen fuel power system also includes multiple sensors for reacting gas pressure, humidity, humidity inside the fuel cell stack, and other operating conditions.

[0082] Specifically, various sensors, flow meters, valve components, etc. reflect the real-time status of the hydrogen fuel cell operation to the hydrogen fuel cell control system. The hydrogen fuel cell control system can ensure that the hydrogen supply system, air supply system and cooling water circulation system can operate in a coordinated and efficient manner to achieve optimal performance.

[0083] The hydrogen fuel power system for the telescopic arm forklift of the present invention can achieve low-pressure, high-density hydrogen storage and high-purity hydrogen supply through solid-state hydrogen storage. It is reusable, safe, economical, and has good adaptability. It has the characteristics of fast hydrogen conduction speed and fast heat conversion speed, which is beneficial to the reaction of hydrogen in the fuel cell.

[0084] Then, the parameters of the hydrogen fuel power system are matched, which specifically includes the following steps:

[0085] S11, determining the configuration parameters of the drive motor;

[0086] S111. Determine the rated power and peak power required by the drive motor;

[0087] When a telescopic forklift is fully loaded, the motor power can be determined based on three dynamic indicators: the maximum driving speed of the vehicle, the slope angle, and the acceleration time of the vehicle from 0 to 50 km / h.

[0088] The rated power of the drive motor should be greater than the power at the highest vehicle speed, and the peak power of the drive motor must be able to ensure that the vehicle meets the above three dynamic indicators.

[0089] S112. Calculate the rated torque of the drive motor according to the rated power and rated speed of the drive motor, and calculate the rated torque of the drive motor according to the peak power and peak speed of the drive motor, thereby obtaining the required configuration parameters of the motor.

[0090] Specifically, the configuration parameters of the motor include rated voltage, rated power, peak power, rated torque, peak torque, rated speed and peak speed.

[0091] S12. Determine the output power and operating range of the fuel cell;

[0092] The hydrogen fuel cell system should meet the power requirements of fuel cell vehicles at common speeds. The common speed of telescopic forklifts is 20-40 km / h. The output power of the fuel cell is calculated based on the full load mass of the vehicle, the DC / DC working efficiency, the power consumption of the vehicle's auxiliary electrical equipment, and the common speed of the telescopic forklift, and the efficiency of the motor and its inverter.

[0093] As the power of hydrogen fuel cells increases, the efficiency of the fuel cell system first rises rapidly to a relatively stable area, and then slowly decreases. In order to ensure the working efficiency of the fuel cell system, the fuel cell system high-efficiency working range is divided, and the minimum working power P of the fuel cell high-efficiency working range is set. fcmin , the maximum working power P in the efficient working range rcmax When the telescopic forklift is driving, the fuel cell should be ensured to operate in the high efficiency range and try to operate in the highest efficiency area. fcmax or less than P fcmin When the power is high, the lithium battery performs "peak shaving and valley filling", making the fuel cell system operate smoothly and keeping it in the high-efficiency working range as much as possible, reducing the fluctuation of output power.

[0094] S13. Determine the output power and operating range of the lithium battery based on actual usage needs.

[0095] Lithium-ion batteries are storage batteries that power telescopic forklifts. The output power of the lithium-ion battery is determined based on actual usage requirements and the maximum mileage the telescopic forklift should be able to travel at the required speed in a purely electric state.

[0096] The division of lithium battery working area is mainly to achieve shallow charge and shallow discharge of lithium battery, thereby increasing the service life of lithium battery. The voltage of lithium battery increases with the increase of the remaining capacity (State of Charge, SOC) of the battery. When the SOC is too high or too low, the voltage of lithium battery will be too high or too low, which will affect the battery performance and even directly damage the lithium battery. You can set the minimum remaining capacity SOC of lithium battery. min =0.2, maximum remaining power SOC max =0.8, assuming the expected value of the remaining power of the lithium battery SOC* is the average of the two, then SOC*=0.5.

[0097] By selecting and matching the drive motor, fuel cell and lithium battery, the reliability of the telescopic forklift can be improved and the usage requirements can be met.

[0098] Example 2:

[0099] During the operation of a telescopic forklift, for example, when accelerating or climbing a slope, the lithium-ion battery can provide instantaneous power. This instantaneous power from the lithium-ion battery acts as a "peak-shaving" mechanism, ensuring stable operation of the fuel cell system and maximizing its efficiency, thereby reducing output power fluctuations. During braking, the lithium-ion battery is responsible for recovering braking energy. Under certain operating conditions, such as when hydrogen levels are insufficient, a telescopic forklift powered by hydrogen can operate solely in pure electric mode for a certain distance.

[0100] The hybrid structure of fuel cells and lithium batteries can better adapt to the complex and changeable working conditions of telescopic arm forklifts. The addition of lithium batteries can make up for the shortcomings of slow dynamic response of fuel cells. Through energy management, the fuel cell and lithium batteries can be flexibly coordinated to make the fuel cell work stably in a high-efficiency area.

[0101] like Figure 2 As shown, a control method for a hydrogen fuel power system for a telescopic forklift is implemented based on the hydrogen fuel power system for a telescopic forklift described in Example 1. The method includes:

[0102] S21. When the telescopic forklift starts, it is powered solely by the lithium battery;

[0103] S22, after the hydrogen fuel cell system reaches the starting temperature, obtain the current vehicle power demand and lithium battery SOC;

[0104] S23. Based on the current vehicle power demand and lithium battery SOC, combined with the efficient working range of the hydrogen fuel cell system and the SOC range of the lithium battery, determine whether to start the hydrogen fuel cell system, and adjust the output power of the hydrogen fuel cell system and lithium battery in real time.

[0105] Specifically, when the telehandler starts, the lithium-ion battery alone powers the system, as the fuel cell needs to be preheated. When the fuel cell reaches startup temperature, whether the fuel cell system starts is determined by the lithium-ion battery's SOC and the vehicle's required power.

[0106] When the vehicle's power demand is very low and the lithium battery SOC is very high, the fuel cell stops working; when the power demand is very high or the lithium battery SOC is very low, the fuel cell starts; when the power demand is not high and the lithium battery SOC is moderate, the fuel cell can maintain the on / off state at the last moment, avoiding frequent starting and stopping of the fuel cell and increasing its service life.

[0107] During the fuel cell output power control process, the fuel cell output power is the fuel cell demand power after correction by the lithium battery SOC value. By adjusting the fuel cell power output, the lithium battery SOC tends to the expected value SOC*. In addition, it is necessary to consider the situation that the fuel cell and the motor charge the lithium battery at the same time when the vehicle brakes, and limit the charging power of the lithium battery.

[0108] To ensure the economy of fuel cell vehicles, the fuel cell output power should be within the set P fcmax and P fcmin Between, and try to work in the most efficient area, first determine whether the lithium battery SOC is greater than SOC min And whether the vehicle's required power is less than P fcmax If the above conditions are met at the same time, the fuel cell will work in the highest efficiency area. The fuel cell working in the highest efficiency area means that the fuel cell has a certain amount of hydrogen and oxygen to generate electricity. If the above conditions cannot be met at the same time, it means that the vehicle requires a large power or the lithium battery needs to be charged, and the working point of the fuel cell is limited to P fcmax and P fcmin between.

[0109] In a more specific embodiment, step S23 includes the following steps:

[0110] a. If lithium battery SOC>SOC min , and the vehicle's required power is less than the maximum working power P in the efficient working range of the hydrogen fuel cell system fcmax , so that the output power of the hydrogen fuel cell system is the maximum working power P fcmax ;

[0111] b. When lithium battery SOC>SOCmax , and the vehicle's required power P re Less than the minimum operating power P in the efficient working range of the hydrogen fuel cell system fcmin The hydrogen fuel cell system can be shut down until the SOC <SOC min When the fuel cell system restarts, in this mode, the output power of the lithium battery is equal to the power required by the vehicle;

[0112] c. When the lithium battery SOC <SOC min , and the vehicle's required power P re Less than the maximum operating power P in the efficient working range of the hydrogen fuel cell system fcmax When the vehicle is fully charged, the hydrogen fuel cell system works alone, assuming the power consumption of the entire vehicle, and at the same time charges the lithium battery with electricity, making its SOC tend to SOC*, and limiting the output power of the hydrogen fuel cell system to P fcmin and P fcmax In this mode, the lithium battery power P b and fuel cell power P fc They are:

[0113]

[0114] P fc =P re -P b

[0115] P fcmin ≤P fc ≤P fcmax

[0116] Where, P ch is the charging coefficient of the lithium battery, at this time the lithium battery power P b If it is less than 0, it means the lithium battery is charging.

[0117] d. When the lithium battery SOC max >SOC>SOC*, and the vehicle's required power P re Greater than the maximum operating power P in the efficient working range of the hydrogen fuel cell system fcmax The hydrogen fuel cell system and lithium battery jointly provide energy for the vehicle, while limiting the output power of the hydrogen fuel cell system to P fcmin and P fcmax In this mode, the lithium battery power P b and fuel cell power P fc They are:

[0118]

[0119] P fc =P re Pb

[0120] P fcmin ≤P fc ≤P fcmax

[0121] Among them, P dis is the lithium battery discharge coefficient, lithium battery power P b If it is greater than 0, it means the lithium battery is discharging.

[0122] e. When the lithium battery SOC min <SOC≤SOC*, and the vehicle's required power Pre is greater than the maximum operating power P in the efficient working range of the hydrogen fuel cell system fcmax , so that the fuel cell cannot be driven alone, and the insufficient power is provided by the lithium battery. At this time, the lithium battery power P b and fuel cell power P fc They are:

[0123] P fc =P fcmax

[0124] P b =P re -P fc

[0125] Furthermore, step S23 further includes:

[0126] f. When the telescopic forklift brakes, if the telescopic forklift uses motor braking and the lithium battery SOC ≤ SOC max , the hydrogen fuel cell system is shut down and the braking energy generated by the motor is recovered by the lithium battery.

[0127] Braking energy recovery is based on the principles of driving safety and fuel economy. Braking energy can be recovered through braking energy recovery, thereby improving the fuel economy of the entire vehicle.

[0128] In addition, to prevent excessive power changes from causing damage to the fuel cell, a RateLimiter module can be added. According to the fuel cell system manufacturer's information, its power increase rate limit is set to 10kW / s and its decrease rate limit is set to -15kW / s.

[0129] The control method of the present invention is based on the current power demand of the entire vehicle and the current SOC of the lithium battery, combined with the high-efficiency working range of the fuel cell and the range of the SOC of the lithium battery, to distribute and manage the working mode and output power of the lithium battery and the fuel cell, so that the lithium battery and the fuel cell can operate in the high-efficiency range as much as possible. While meeting the power performance of the entire vehicle, the utilization efficiency and durability of the lithium battery and the fuel cell are improved, thereby improving the fuel economy of the entire vehicle.

[0130] Control strategy is one of the core technologies of hydrogen fuel cell telescopic forklifts. Through the hydrogen fuel power system control method, the vehicle's operating status and energy distribution are controlled. The control strategy can coordinate the working status of all components of the vehicle so that they all operate in a relatively ideal area. While meeting the complex and changeable working conditions of the telescopic forklift, it can also make the entire vehicle operate in the best state, thereby significantly improving the vehicle's power, fuel economy and the service life of each component.

[0131] Example 3:

[0132] During the actual driving process of the telescopic arm forklift, the entire vehicle needs to change load frequently, but the frequent changes in output power can easily cause problems such as insufficient reaction gas and voltage fluctuations in the fuel cell, ultimately leading to a decline in fuel cell performance and durability.

[0133] To this end, the present invention provides a control method for a hydrogen fuel power system for a telescopic forklift, further comprising:

[0134] S31. Analyze the power demand of the entire vehicle according to the operating conditions of the telescopic forklift to obtain a time domain graph of the power demand of the entire vehicle, convert the time domain graph into a frequency domain graph using a fast Fourier transform, and perform frequency domain analysis on the power demand of the entire vehicle;

[0135] S32. Based on the results of the frequency domain analysis, a low-pass filter is used to filter the power demand of the entire vehicle, and the low-frequency power demand is used as the power demand for the hydrogen fuel cell system, and the high-frequency power demand is transmitted to the lithium battery.

[0136] The power demand of the telescopic arm forklift is relatively large in the low-frequency part of 0-0.1Hz. Therefore, a low-pass filter can be used to filter the power demand of the vehicle, and the low-frequency power demand is used as the power demand for the fuel cell system, while the high-frequency power demand is passed to the lithium battery.

[0137] The low-pass filter can effectively reduce the fluctuation of the required power, and the different cutoff frequency settings have a significant impact on the filtering results of the low-pass filter. The smaller the cutoff frequency, the relatively smaller the power signal that passes through the low-pass filter, and the smoother the vehicle's required power curve. Therefore, the low-pass filter can be used to filter the vehicle's required power, and the filtered signal is used as the fuel cell system's required power, which is beneficial to reducing the power fluctuation of the fuel cell system and extending its service life. The fluctuation of the required power is borne by the lithium battery. However, if a filter with a fixed cutoff frequency is used, the cutoff frequency of the low-pass filter needs to be set in advance. When the setting is too high, the low-pass filter cannot play a good filtering role, and the fuel cell's required power fluctuates greatly; when the setting is too low, the power requirement for the lithium battery will increase, the fuel cell cannot be fully utilized, and its working efficiency is low.

[0138] In view of the complex and changeable working conditions of telescopic forklifts and the results of frequency domain analysis, a low-pass filter with adjustable cutoff frequency is adopted, which can not only play a filtering role but also make full use of the fuel cell.

[0139] During the operation of the vehicle, the cutoff frequency is adjusted online using a fuzzy controller, and the required power of the vehicle is allocated in combination with the logic rules in the power following control strategy.

[0140] Figure 3 FIG. 1 is a schematic diagram of the operation of an adaptive low-pass filter provided by the third embodiment of the present invention. Figure 3 As shown, the lithium battery SOC and the vehicle required power P re As two input variables, the low-pass filter cutoff frequency f c As the output variable, a dual-input-single-output fuzzy controller is designed to adaptively adjust the cutoff frequency of the low-pass filter, thereby forming an adaptive low-pass filter.

[0141] First, determine the basic domain of each variable and set the basic domain of lithium battery SOC to [0,1]. According to the drive motor parameters, the vehicle required power P re The basic domain of the low-pass filter is set to [0,250]; in order to ensure that the low-pass filter can better suppress the fluctuation of the required power, the cutoff frequency of the low-pass filter f is set to c The basic domain is set to [0,0.1], and the three variables are divided into five fuzzy subsets: very low, low, medium, high, and very high, and are represented by {VL, L, M, H, VH}. The membership function of each variable is a combination of triangle and trapezoid.

[0142] For example, the SOC of lithium batteries can be divided into: 0-10%, 10-20%, 20-60%, 60-80%, 80-100%, of which 20-60% is the efficient working area of lithium battery SOC. re It can be divided into: 0-6kW, 6-12kW, 12-20kW, 20-30kW, 30-35kW, among which 20kW is the rated power required by the telescopic arm forklift, 35kW is the maximum power required by the telescopic arm forklift, and 12-20kW is the efficient working area of the telescopic arm forklift.

[0143] When the lithium battery SOC is lower than 20% and the vehicle power requirement P re When the fuzzy controller is larger than 12kW, it should output a larger cut-off frequency f c , that is, the output cutoff frequency f c The frequency is greater than the cut-off frequency set by the low-pass filter, so that the fuel cell can bear greater power output to ensure the power of the vehicle. When the lithium battery SOC is higher than 60% and the vehicle power demand P reWhen the fuzzy controller outputs a smaller cutoff frequency f c , that is, the output cutoff frequency f c It is smaller than the cut-off frequency set by the low-pass filter, so that the power fluctuation required by the fuel cell is smaller, which is beneficial to improving the durability of the fuel cell.

[0144] An adaptive low-pass filter is added on the basis of the power-following energy management strategy. The adaptive low-pass filter can adaptively adjust the cutoff frequency of the low-pass filter according to the current state of the vehicle. The filtering function of the low-pass filter is used to divide the required power of the entire vehicle into low-frequency and high-frequency parts with the cutoff frequency as the boundary. The power of the low-frequency part is provided by the fuel cell after adjustment according to the logical rules, and the power of the high-frequency part is provided by the lithium battery.

[0145] Adding an adaptive low-pass filter to the power-following energy management strategy can reduce the fluctuation of fuel cell power demand during the actual driving of the telescopic arm forklift, thereby improving the durability of the fuel cell.

[0146] Example 4:

[0147] An embodiment of the present invention provides a fuel cell controller for a hydrogen fuel power system for a telescopic boom forklift, wherein the fuel cell controller is used to execute the control method of the hydrogen fuel power system of the aforementioned embodiment 2 or embodiment 3.

[0148] Embodiment 5:

[0149] like Figure 4 As shown, an embodiment of the present invention provides a hydrogen fuel power system for a telescopic arm forklift, which also includes: a vehicle controller, a battery management system, a motor controller, a drive motor and a gearbox and other components. The vehicle controller is communicated with the fuel cell controller, battery management system, motor controller and gearbox and other components through a CAN bus, the battery management system is connected to the lithium battery, and the fuel cell controller is communicated with the battery management system through a CAN bus, forming a distributed hierarchical control structure.

[0150] The vehicle controller is the core control component of a hydrogen fuel cell. It collects relevant control signals from the driver and receives status information from the vehicle's component controllers. Through internal calculations and decision-making, it outputs control instructions to each component controller via the CAN bus, enabling coordinated operation of each component. The vehicle control strategy is implemented through the vehicle controller's software management layer, which analyzes driver-related signals and status information from component controllers, and makes decisions based on pre-set algorithms.

[0151] Depending on the operating conditions, the telehandler's operating status information, including the throttle, brake pedal, transmission gear position, and key, is transmitted to the vehicle controller. The vehicle controller analyzes this information, along with status information from each component controller, and outputs control instructions to each component controller.

[0152] The fuel cell controller obtains the current vehicle power demand and the current lithium battery SOC from the vehicle controller and battery management system.

[0153] Example 6

[0154] Figure 5 A telescopic forklift provided in an embodiment of the present invention includes the hydrogen fuel power system for the telescopic forklift described in the first or fifth embodiment.

[0155] The telescopic arm forklift provided in the embodiment of the present invention can execute the control method of the hydrogen fuel power system of the aforementioned embodiment of the present invention, and has the corresponding functional modules and beneficial effects of the execution method.

[0156] The present invention has been disclosed above with preferred embodiments, which are not intended to limit the present invention. Any technical solutions obtained by adopting equivalent replacement or equivalent transformation solutions fall within the protection scope of the present invention.

Claims

1. A method for controlling a hydrogen fuel power system for a telescopic forklift, wherein the hydrogen fuel power system comprises a hydrogen fuel cell system and a lithium battery, wherein the hydrogen fuel cell system and the lithium battery are used to power the electrical system of the telescopic forklift, and the hydrogen fuel cell system is also used to charge the lithium battery, characterized in that: The method comprises: When the telescopic forklift starts, it is powered solely by the lithium battery; After the hydrogen fuel cell system reaches the starting temperature, obtain the current vehicle power demand and lithium battery SOC; Based on the current vehicle power demand and lithium battery SOC, combined with the efficient operating range of the hydrogen fuel cell system and the SOC range of the lithium battery, determine whether to start the hydrogen fuel cell system and adjust the output power of the hydrogen fuel cell system and lithium battery in real time; The power demand of the entire vehicle is analyzed according to the working conditions of the telescopic arm forklift, and a time domain diagram of the power demand of the entire vehicle is obtained. The time domain diagram is converted into a frequency domain diagram, and a frequency domain analysis of the power demand of the entire vehicle is performed based on the frequency domain diagram; Based on the results of frequency domain analysis, a low-pass filter with adjustable cutoff frequency is used to filter the vehicle's power demand. The low-frequency power demand is used as the power demand for the hydrogen fuel cell system, and the high-frequency power demand is passed to the lithium battery. The cutoff frequency of the low-pass filter is adjusted online by a fuzzy controller, including: Input the vehicle's required power and lithium battery SOC into the fuzzy controller; The fuzzy controller outputs the cutoff frequency of the low-pass filter based on the vehicle's required power and the lithium battery SOC, combined with pre-set judgment rules, including: When the lithium battery SOC is lower than the minimum SOC of the lithium battery SOC efficient working area and the vehicle demand power is greater than the minimum demand power of the telescopic arm forklift efficient working area, the cutoff frequency output by the fuzzy controller is greater than the cutoff frequency set by the low-pass filter; When the lithium battery SOC is higher than the maximum SOC in the lithium battery SOC efficient working area and the vehicle demand power is less than the minimum demand power in the telescopic arm forklift efficient working area, the cutoff frequency output by the fuzzy controller is less than the cutoff frequency set by the low-pass filter.

2. The control method of a hydrogen fuel power system for a telescopic forklift according to claim 1, characterized in that: The method of determining whether to start the hydrogen fuel cell system and adjust the output power of the hydrogen fuel cell system and the lithium battery in real time based on the current vehicle power demand and the lithium battery SOC, combined with the efficient working range of the hydrogen fuel cell system and the SOC range of the lithium battery, includes: If lithium battery SOC>SOC min The required power of the vehicle is less than the maximum working power P of the hydrogen fuel cell system in the efficient working range. fcmax , so that the output power of the hydrogen fuel cell system is the maximum working power P fcmax ; If lithium battery SOC> SOC max , and the vehicle's required power is less than the minimum working power P in the efficient working range of the hydrogen fuel cell system fcmin , the hydrogen fuel cell system stops working, and the lithium battery output power is equal to the vehicle's required power; where SOC max The maximum remaining capacity in the lithium battery SOC range; If lithium battery SOC< SOC min , and the vehicle's required power is less than the maximum working power P in the efficient working range of the hydrogen fuel cell system fcmax , the hydrogen fuel cell system is turned on, assuming the power consumption of the entire vehicle, and at the same time charging the lithium battery with electricity, making its SOC tend to the expected value of the remaining power SOC*, and limiting the output power of the hydrogen fuel cell system to P fcmin and P fcmax Between; among which SOC min The lowest remaining power in the lithium battery SOC range; If the lithium battery SOC max >SOC>SOC*, and the vehicle's required power P re Greater than the maximum operating power P in the efficient working range of the hydrogen fuel cell system fcmax The hydrogen fuel cell system and lithium battery jointly provide energy for the vehicle, while limiting the output power of the hydrogen fuel cell system to P fcmin and P fcmax between; If the lithium battery SOC min < SOC≤SOC*, and the vehicle's required power P re Greater than the maximum operating power P in the efficient working range of the hydrogen fuel cell system fcmax , so that the output power of the hydrogen fuel cell system is the maximum working power P fcmax , the insufficient power is provided by the lithium battery.

3. The control method of a hydrogen fuel power system for a telescopic forklift according to claim 1, characterized in that: Also includes: When the telescopic forklift brakes, if the telescopic forklift uses motor braking and the lithium battery SOC ≤ SOC max , the hydrogen fuel cell system is shut down, and the braking energy generated by the motor is recovered by the lithium battery, where SOC max It is the highest remaining power in the lithium battery SOC range.

4. A fuel cell controller for a hydrogen fuel power system for a telescopic forklift, characterized in that: The fuel cell controller is used to execute the control method of the hydrogen fuel power system according to any one of claims 1 to 3.

5. A hydrogen fuel power system for a telescopic arm forklift, comprising a hydrogen fuel cell system, a lithium battery, a DC / DC module and the fuel cell controller according to claim 4, the fuel cell controller being connected to the hydrogen fuel cell system, the output end of the hydrogen fuel cell system stack being connected to the DC / DC module, the DC / DC module being connected to the lithium battery, and both the DC / DC module and the lithium battery being connected to the power system of the telescopic arm forklift, wherein the DC / DC module is used to stabilize the output voltage of the hydrogen fuel cell system stack, and to charge the lithium battery and supply power to the power system of the telescopic arm forklift according to control instructions issued by the fuel cell controller; the lithium battery is used to supply power to the power system in the telescopic arm forklift according to control instructions issued by the fuel cell controller, and to satisfy the function of one-touch power-on by the key.

6. The hydrogen fuel power system for a telescopic forklift according to claim 5, characterized in that: The hydrogen fuel cell system uses solid-state hydrogen storage as a hydrogen source.

7. The hydrogen fuel power system for a telescopic forklift according to claim 5, characterized in that: Also includes: The vehicle controller, battery management system, motor controller and gearbox are connected to the fuel cell controller, battery management system, motor controller and gearbox through the CAN bus. The battery management system is connected to the lithium battery. The fuel cell controller communicates with the battery management system through the CAN bus. The vehicle controller collects relevant control signals from the driver and receives status information feedback from the fuel cell controller, battery management system, motor controller and gearbox. Through internal calculation and decision-making, it outputs control instructions to the controllers of each component via the CAN bus to make each component work in coordination.

8. A telescopic forklift, characterized in that: A hydrogen fuel power system for a telescopic forklift comprising the hydrogen fuel power system according to any one of claims 5 to 7.

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