A control method for a fuel cell vehicle

Abstract

The present application discloses a control method for a fuel cell vehicle, which relates to the field of fuel cell vehicles. In the control method, during the driving of the vehicle, the stable power output by the fuel cell is used as the main power source of the whole vehicle. When the power demand of the whole vehicle is greater than the output power of the fuel cell, the energy storage battery is used to compensate for the power demand of the whole vehicle; when the power demand of the whole vehicle is less than the output power of the fuel cell, the energy storage battery is used as an energy storage device to recover the remaining power output of the fuel cell, thereby reducing the load mutation and the number of starts and stops of the fuel cell on the basis of meeting the power performance and transient response of the whole vehicle, ensuring the acceleration performance requirements of the whole vehicle while protecting the service life of the fuel cell.

Description

Technical Field

[0001] The present application relates to the field of fuel cell vehicles, and in particular to a control method for a fuel cell vehicle. Background Art

[0002] Fuel cell vehicles, as clean energy vehicles, will gradually become the main models in the new energy field in the future. However, due to the chemical energy conversion efficiency of the fuel cell itself, compared with energy storage batteries such as lithium batteries, the output power of the fuel cell is relatively flat. Therefore, in order to better drive the vehicle, current fuel cell vehicles generally use a parallel power supply structure of fuel cells and energy storage batteries or an extended-range power supply structure to jointly drive the vehicle.

[0003] Since this type of fuel cell vehicle has two different built-in energy sources, and different energy sources have different output characteristics, how to coordinate the working processes of the fuel cell and the energy storage battery to ensure the power of the entire vehicle while extending the service life of the fuel cell as much as possible has become a key research direction for optimizing the overall performance of fuel cell vehicles. Summary of the invention

[0004] In view of the above problems and technical requirements, the applicant has proposed a control method for a fuel cell vehicle. The technical solution of the present application is as follows:

[0005] A control method for a fuel cell vehicle, the control method comprising:

[0006] During the operation of the fuel cell vehicle, the power demand of the entire vehicle is determined according to the real-time vehicle speed of the fuel cell vehicle and the state signal of the accelerator pedal;

[0007] During the driving of the fuel cell vehicle, the fuel cell is controlled to generate electricity according to the optimal output power;

[0008] When the power demand of the whole vehicle is greater than the optimal output power of the fuel cell, the energy storage battery is controlled to discharge according to the extra power, and the extra power is the power that the power demand of the whole vehicle exceeds the optimal output power of the fuel cell;

[0009] When the power demand of the whole vehicle exceeds the optimal output power of the fuel cell, the surplus power is used to charge the energy storage battery. The surplus power is the power that exceeds the power demand of the whole vehicle by the optimal output power of the fuel cell.

[0010] A further technical solution is that the fuel cell includes a plurality of optimal output powers, and the method for controlling the fuel cell to generate electricity according to the optimal output power that meets the power demand of the whole vehicle includes:

[0011] The optimal output power of the fuel cell is determined according to the SOC value of the energy storage battery. The lower the SOC value of the energy storage battery, the fuel cell is controlled to generate electricity at a higher optimal output power; the higher the SOC value of the energy storage battery, the fuel cell is controlled to generate electricity at a lower optimal output power.

[0012] A further technical solution is that the control method further comprises:

[0013] When the vehicle power demand is greater than the optimal output power of the fuel cell, and the additional power is less than or equal to the maximum discharge power of the energy storage battery, the fuel cell is kept generating electricity at the optimal output power and the discharge power of the energy storage battery is adjusted according to the additional power.

[0014] A further technical solution is that the fuel cell includes several optimal output powers, and the control method further includes:

[0015] When the power demand of the whole vehicle is greater than the optimal output power of the fuel cell, and the additional power is greater than the maximum discharge power of the energy storage battery, the fuel cell is controlled to increase the output power and generate electricity according to the higher optimal output power; until the additional power is less than or equal to the maximum discharge power of the energy storage battery, the fuel cell is kept generating electricity according to the optimal output power and the discharge power of the energy storage battery is adjusted according to the additional power.

[0016] A further technical solution is that the control method further comprises:

[0017] When the additional power when the fuel cell generates electricity at the highest optimal output power is still greater than the maximum discharge power of the energy storage battery, the fuel cell is controlled to generate electricity according to the power demand of the entire vehicle until the additional power when the fuel cell generates electricity at the highest optimal output power is less than or equal to the maximum discharge power of the energy storage battery, and the fuel cell is controlled to switch back to generating electricity at the optimal output power.

[0018] A further technical solution is that the control method further comprises:

[0019] In the process of controlling the fuel cell to generate electricity according to the optimal output power, when it is detected that the decreasing rate of the SOC value of the energy storage battery reaches a rate threshold, the fuel cell is controlled to increase the output power.

[0020] A further technical solution is that the control method further comprises:

[0021] When the real-time vehicle speed of the fuel cell vehicle is 0 and the state signal of the accelerator pedal is in the initial state and it is determined that the fuel cell vehicle is in a stationary state, when the SOC value of the energy storage battery is greater than or equal to the SOC lower limit threshold, the fuel cell is controlled to remain closed and the energy storage battery is used to discharge according to the power demand of the entire vehicle; when the SOC value of the energy storage battery is less than the SOC lower limit threshold, the fuel cell is controlled to generate electricity according to the power demand of the entire vehicle and charge the energy storage battery according to the continuous charging power of the energy storage battery.

[0022] A further technical solution is that the state signal of the accelerator pedal includes the opening degree of the accelerator pedal, and the power demand of the whole vehicle is determined according to the real-time vehicle speed of the fuel cell vehicle and the state signal of the accelerator pedal, including:

[0023] Determine the vehicle demand torque corresponding to the accelerator pedal opening and the real-time vehicle speed in the torque demand table, and determine the vehicle power demand corresponding to the vehicle demand torque; the torque demand table indicates the vehicle demand torque at different accelerator pedal openings and real-time vehicle speeds.

[0024] A further technical solution is that the state signal of the accelerator pedal also includes the opening degree and the change rate of the accelerator pedal, and the method for determining the vehicle power demand corresponding to the vehicle required torque also includes:

[0025] Determine the correction factor corresponding to the accelerator pedal opening and the accelerator pedal change rate in the torque correction table, and use the correction factor to correct the vehicle demand torque to determine the vehicle power demand corresponding to the corrected vehicle demand torque; the torque correction table indicates the correction factor under different accelerator pedal openings and accelerator pedal change rates.

[0026] A further technical solution is that the control method further comprises:

[0027] During the driving process of the fuel cell vehicle, when the SOC value of the energy storage battery is greater than or equal to the SOC upper limit threshold, the fuel cell is controlled to remain closed and the energy storage battery is used to discharge according to the power demand of the whole vehicle; otherwise, the step of controlling the fuel cell to generate electricity according to the optimal output power that meets the power demand of the whole vehicle is executed.

[0028] The beneficial technical effects of this application are:

[0029] The present application discloses a control method for a fuel cell vehicle. During the driving process of the vehicle, the control method uses the stable power output by the fuel cell as the main power source of the whole vehicle. When the power demand of the whole vehicle is greater than the output power of the fuel cell, the energy storage battery is used to compensate for the power demand of the whole vehicle. When the power demand of the whole vehicle is less than the output power of the fuel cell, the energy storage battery is used as an energy storage device to recover the remaining power output of the fuel cell, thereby reducing the load mutation and the number of starts and stops of the fuel cell on the basis of meeting the power performance and transient response of the whole vehicle, ensuring the acceleration performance requirements of the whole vehicle while protecting the service life of the fuel cell. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 It is a method flow chart of a control method of a fuel cell vehicle in one embodiment of the present application.

[0031] Figure 2 It is a method flow chart of a control method of a fuel cell vehicle in another embodiment of the present application. DETAILED DESCRIPTION

[0032] The specific implementation of the present application is further described below in conjunction with the accompanying drawings.

[0033] This application discloses a control method for a fuel cell vehicle. Please refer to Figure 1 The control method includes the following steps:

[0034] Step 1: During the operation of the fuel cell vehicle, the power requirement of the entire vehicle is determined according to the real-time vehicle speed of the fuel cell vehicle and the status signal of the accelerator pedal. The fuel cell vehicle in this application has built-in fuel cells and energy storage batteries. The fuel cells and energy storage batteries can adopt a parallel structure or an extended-range structure.

[0035] In one embodiment, please refer to Figure 2 The state signal of the accelerator pedal includes the opening of the accelerator pedal, determines the vehicle demand torque corresponding to the opening of the accelerator pedal and the real-time vehicle speed in the torque demand table, and determines the vehicle power demand corresponding to the vehicle demand torque. The torque demand table is pre-fitted, and the torque demand table indicates the vehicle demand torque at different accelerator pedal openings and real-time vehicle speeds. The corresponding relationship between the vehicle demand torque and the vehicle power demand is also pre-established.

[0036] In another embodiment, it is also necessary to detect whether there is an acceleration demand in the current power output, and the state signal of the accelerator pedal also includes the opening degree and the change rate of the accelerator pedal, determine the correction factor corresponding to the opening degree and the change rate of the accelerator pedal in the torque correction table, and use the correction factor to correct the vehicle demand torque, and finally determine the vehicle power demand corresponding to the corrected vehicle demand torque. The torque correction table indicates the correction factors under different accelerator pedal opening degrees and accelerator pedal change rates.

[0037] In this step, the working process of the fuel cell vehicle refers to the stage after the fuel cell vehicle is started, which mainly includes two operating modes: driving mode and stationary mode. During the driving process of the fuel cell vehicle, the acceleration and deceleration of the fuel cell vehicle vary greatly, so the power demand of the whole vehicle generally fluctuates. While in the stationary process of the fuel cell vehicle, the power demand of the whole vehicle of the fuel cell vehicle remains basically unchanged.

[0038] Step 2: During the driving of the fuel cell vehicle, the fuel cell is controlled to generate electricity according to the optimal output power.

[0039] The optimal output power of the fuel cell is obtained by pre-fitting the working characteristic curve of the fuel cell, and is the output power that makes the power generation efficiency of the fuel cell optimal. The fuel cell generally includes several optimal output powers. In this step, the optimal output power adopted by the fuel cell is determined according to the SOC value of the energy storage battery. The lower the SOC value of the energy storage battery, the more the fuel cell is controlled to generate electricity with a higher optimal output power; the higher the SOC value of the energy storage battery, the more the fuel cell is controlled to generate electricity with a lower optimal output power.

[0040] Step 3: When the vehicle power demand is greater than the optimal output power of the fuel cell, the energy storage battery is controlled to discharge according to the additional power. The additional power is the power that the vehicle power demand exceeds the optimal output power of the fuel cell. There are several different situations:

[0041] When the vehicle power demand is greater than the optimal output power of the fuel cell, and the extra power is less than or equal to the maximum discharge power of the energy storage battery, the fuel cell is kept generating electricity at the optimal output power, and the discharge power of the energy storage battery is adjusted according to the extra power. That is, for example, when the vehicle power demand increases due to sudden acceleration of the fuel cell vehicle, the output power of the fuel cell remains unchanged, and the transient load power is provided by the energy storage battery, which not only meets the acceleration performance requirements of the vehicle, but also avoids the fuel cell life being affected by the sudden load change.

[0042] When the power demand of the whole vehicle is greater than the optimal output power of the fuel cell, and the additional power is greater than the maximum discharge power of the energy storage battery, that is, even if the functional output of the fuel cell and the energy storage battery cannot meet the power demand of the whole vehicle, it is necessary to control the fuel cell to increase the output power and generate electricity according to the higher optimal output power. Until the additional power is less than or equal to the maximum discharge power of the energy storage battery, keep the fuel cell generating electricity according to the optimal output power unchanged, and adjust the discharge power of the energy storage battery according to the additional power. For example, the optimal output power of the fuel cell includes 60KW, 70KW and 80KW. When the additional power of the fuel cell at 60KW output is greater than the maximum discharge power of the energy storage battery. Increase the output of the fuel cell to 70KW. If the additional power at this time is less than or equal to the maximum discharge power of the energy storage battery, keep the fuel cell output at 70KW and adjust the discharge power of the energy storage battery according to the additional power.

[0043] When the additional power of the fuel cell when generating electricity according to the highest optimal output power is still greater than the maximum discharge power of the energy storage battery, for example, in the above example, when the additional power of the fuel cell when the output is increased to 70KW is still greater than the maximum discharge power of the energy storage battery, and the additional power of the fuel cell when the output is further increased to 80KW is still greater than the maximum discharge power of the energy storage battery, the fuel cell will be controlled to generate electricity according to the power demand of the whole vehicle, not according to the optimal output power. However, as the vehicle runs, the power demand will decrease, and the fuel cell will also charge the energy storage battery. After working for a period of time, it will still recover to meet the condition that the additional power of the fuel cell when generating electricity according to the highest optimal output power is less than or equal to the maximum discharge power of the energy storage battery, and the fuel cell will be controlled to switch back to generating electricity according to the optimal output power. That is, after temporarily increasing the output power of the fuel cell, it will switch back to generating electricity according to the optimal output power in a timely manner.

[0044] Step 4: When the vehicle power demand is less than the optimal output power of the fuel cell, the energy storage battery is charged with the surplus power, which is the power of the optimal output power of the fuel cell exceeding the vehicle power demand. That is, for example, when the vehicle power demand decreases due to a sudden deceleration of the fuel cell vehicle, the output power of the fuel cell remains unchanged, and the surplus power is used to charge the energy storage battery. This can meet the acceleration performance requirements of the vehicle while also preventing the fuel cell from affecting its life due to sudden load changes.

[0045] During the driving process of the fuel cell vehicle, when the fuel cell and the energy storage battery are controlled to supply energy in combination according to the control method of the present application, in the process of controlling the fuel cell to generate electricity according to the optimal output power, when it is detected that the rate of decrease of the SOC value of the energy storage battery reaches the rate threshold, the fuel cell is controlled to increase the output power. The same as the above method of increasing the output power, one case is to control the fuel cell to generate electricity according to the optimal output power with higher power until the rate of decrease of the SOC value of the energy storage battery is less than the rate threshold. Another case is that when the fuel cell generates electricity according to the optimal output power with the highest power, the rate of decrease of the SOC value of the energy storage battery still reaches the rate threshold, the output power of the fuel cell is further increased, and the power is not generated according to the optimal output power until the rate of decrease of the SOC value of the energy storage battery is less than the rate threshold. The specific increase in the output power of the fuel cell can be preset. That is, in the process of mixed energy supply of the fuel cell and the energy storage battery, the SOC value of the energy storage battery should be kept unchanged as much as possible or gradually charged and increased, otherwise the output function of the fuel cell should be increased to maintain the SOC value of the energy storage battery.

[0046] During the driving process of the fuel cell vehicle, when the SOC value of the energy storage battery is greater than or equal to the SOC upper limit threshold, the fuel cell is controlled to remain closed and the energy storage battery is used to discharge according to the power demand of the whole vehicle. Otherwise, the output power of the fuel cell and the energy storage battery is distributed according to the SOC of the energy storage battery, that is, the fuel cell and the energy storage battery are used to jointly supply energy according to the above control method provided in this application.

[0047] The above describes the control method during the driving process of the fuel cell vehicle. When the real-time speed of the fuel cell vehicle is 0 and the state signal of the accelerator pedal is in the initial state and the fuel cell vehicle is determined to be in a stationary state, the power demand of the whole vehicle is generally a fixed value, which is mainly used to meet the power of the basic electrical devices of the fuel cell vehicle. Then, when the SOC value of the energy storage battery is greater than or equal to the SOC lower limit threshold, the fuel cell is controlled to remain closed and the energy storage battery is used to discharge according to the power demand of the whole vehicle. When the SOC value of the energy storage battery is less than the SOC lower limit threshold, the fuel cell is controlled to generate electricity according to the power demand of the whole vehicle and to charge the energy storage battery according to the continuous charging power of the energy storage battery, thereby avoiding overcharging of the energy storage battery. And in this case, when the SOC value of the energy storage battery rises to greater than or equal to the SOC lower limit threshold during the charging process, it does not immediately switch to the energy storage battery for energy supply, but continues to output the function and charge by the fuel cell until the energy storage battery is charged to a predetermined state, such as when the SOC value of the energy storage battery is greater than or equal to the upper limit threshold, the fuel cell is turned off and switched to using the energy storage battery to discharge according to the power demand of the whole vehicle.

[0048] The above is only a preferred embodiment of the present application, and the present application is not limited to the above embodiments. It is understood that other improvements and changes directly derived or associated by those skilled in the art without departing from the spirit and concept of the present application should be considered to be included in the protection scope of the present application.

Claims

1. A control method for a fuel cell vehicle, characterized in that: The control method comprises: During the operation of the fuel cell vehicle, the power demand of the entire vehicle is determined according to the real-time vehicle speed of the fuel cell vehicle and the state signal of the accelerator pedal; During the driving process of the fuel cell vehicle, the fuel cell is controlled to generate electricity according to the optimal output power, and the fuel cell includes several optimal output powers; When the vehicle power demand is greater than the optimal output power of the fuel cell, the energy storage battery is controlled to discharge according to the additional power, where the additional power is the power that the vehicle power demand exceeds the optimal output power of the fuel cell; including: When the vehicle power demand is greater than the optimal output power of the fuel cell, and the extra power is less than or equal to the maximum discharge power of the energy storage battery, the fuel cell is kept generating electricity at the optimal output power and the discharge power of the energy storage battery is adjusted according to the extra power; When the power demand of the whole vehicle is greater than the optimal output power of the fuel cell, and the additional power is greater than the maximum discharge power of the energy storage battery, the fuel cell is controlled to increase the output power and generate electricity according to the higher optimal output power until the additional power is less than or equal to the maximum discharge power of the energy storage battery, the fuel cell is kept generating electricity according to the optimal output power and the discharge power of the energy storage battery is adjusted according to the additional power; When the additional power of the fuel cell when generating electricity according to the highest optimal output power is still greater than the maximum discharge power of the energy storage battery, the fuel cell is controlled to generate electricity according to the power demand of the whole vehicle, until the additional power of the fuel cell when generating electricity according to the highest optimal output power is less than or equal to the maximum discharge power of the energy storage battery, the fuel cell is controlled to switch back to generating electricity according to the optimal output power; When the vehicle power demand is less than the optimal output power of the fuel cell, the energy storage battery is charged with surplus power, where the surplus power is the excess of the optimal output power of the fuel cell over the vehicle power demand.

2. The control method according to claim 1, characterized in that: The fuel cell includes several optimal output powers, and the method of controlling the fuel cell to generate electricity according to the optimal output power that meets the power demand of the whole vehicle includes: The optimal output power of the fuel cell is determined according to the SOC value of the energy storage battery. The lower the SOC value of the energy storage battery, the fuel cell is controlled to generate electricity at a higher optimal output power; the higher the SOC value of the energy storage battery, the fuel cell is controlled to generate electricity at a lower optimal output power.

3. The control method according to claim 1, characterized in that: The control method further comprises: In the process of controlling the fuel cell to generate electricity according to the optimal output power, when it is detected that the decreasing rate of the SOC value of the energy storage battery reaches a rate threshold, the fuel cell is controlled to increase the output power.

4. The control method according to claim 1, characterized in that: The control method further comprises: When the real-time vehicle speed of the fuel cell vehicle is 0 and the state signal of the accelerator pedal is in the initial state and it is determined that the fuel cell vehicle is in a stationary state, when the SOC value of the energy storage battery is greater than or equal to the SOC lower limit threshold, the fuel cell is controlled to remain closed and the energy storage battery is used to discharge according to the power demand of the entire vehicle; when the SOC value of the energy storage battery is less than the SOC lower limit threshold, the fuel cell is controlled to generate electricity according to the power demand of the entire vehicle and to charge the energy storage battery according to the continuous charging power of the energy storage battery.

5. The control method according to claim 1, characterized in that: The state signal of the accelerator pedal includes the opening degree of the accelerator pedal. The power demand of the whole vehicle is determined according to the real-time vehicle speed of the fuel cell vehicle and the state signal of the accelerator pedal, including: Determine the vehicle demand torque corresponding to the accelerator pedal opening and the real-time vehicle speed in the torque demand table, and determine the vehicle power demand corresponding to the vehicle demand torque; the torque demand table indicates the vehicle demand torque at different accelerator pedal openings and real-time vehicle speeds.

6. The control method according to claim 5, characterized in that: The state signal of the accelerator pedal also includes the opening degree and the change rate of the accelerator pedal. The method for determining the vehicle power demand corresponding to the vehicle demand torque also includes: Determine the correction factor corresponding to the opening degree of the accelerator pedal and the rate of change of the accelerator pedal in the torque correction table, and use the correction factor to correct the vehicle demand torque to determine the vehicle power demand corresponding to the corrected vehicle demand torque; the torque correction table indicates the correction factor under different accelerator pedal opening degrees and accelerator pedal change rates.

7. The control method according to claim 1, characterized in that: The control method further comprises: During the driving process of the fuel cell vehicle, when the SOC value of the energy storage battery is greater than or equal to the SOC upper limit threshold, the fuel cell is controlled to remain closed and the energy storage battery is used to discharge according to the power demand of the whole vehicle; otherwise, the step of controlling the fuel cell to generate electricity according to the optimal output power that meets the power demand of the whole vehicle is executed.

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