Energy management method for fuel cell hybrid vehicle
By determining the range of output power variation and finding the optimal operating point in fuel cell hybrid vehicles, the problems of wasted computational resources and sudden output power changes in traditional methods are solved, achieving more efficient energy management, extending fuel cell life and improving overall vehicle performance.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-24
- Publication Date
- 2026-03-24
AI Technical Summary
Traditional energy management methods for fuel cell hybrid vehicles fail to consider the dynamic characteristics of fuel cell output power when calculating it, resulting in wasted computing resources and sudden changes in output power, which cannot effectively meet the requirements of vehicle performance and hydrogen consumption economy.
By determining the range of changes in fuel cell output power and finding the optimal operating point within that range based on the equivalent hydrogen consumption theory, the output power of the fuel cell and battery is adjusted, avoiding the need to calculate all possible operating points at each time step and correcting dynamic changes in real time.
It reduces computational load, improves the accuracy of the optimal operating point, avoids sudden changes in fuel cell output power, extends service life, and ensures overall vehicle performance and hydrogen consumption economy.
Smart Images
Figure CN121716583A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present disclosure relates to the field of engineering machinery, vehicles and fuel cell technology, and in particular, to an energy management method of a fuel cell hybrid vehicle. BACKGROUND
[0002] The dynamic characteristics of fuel cells (for example, hydrogen fuel cells) are poor, and when used alone, they cannot follow the load changes of the whole vehicle. Therefore, in general, they are used together with a storage battery (for example, a lithium battery) to make up for the insufficient dynamic response of the fuel cell by using the fast response characteristics of the storage battery.
[0003] Since there are two energy sources, fuel cells and storage batteries, on an FCHEV (Fuel Cell Hybrid Electric Vehicle), it is necessary to ensure the performance of the whole vehicle while meeting the demand for hydrogen consumption economy. At present, for FCHEV, the commonly used energy management method is to use the ECMS (Equivalent Consumption Minimum Strategy) algorithm based on vehicle economy.
[0004] In the power energy management model of the traditional fuel cell hybrid vehicle, in one time step, the algorithm calculates the total equivalent hydrogen consumption for each of all possible working points (in different working points, the whole vehicle load is allocated to the fuel cell and the storage battery in different proportions) based on the input whole vehicle load, and finally selects the optimal working point (i.e., the working point with the minimum total equivalent hydrogen consumption of the fuel cell and the storage battery) and sets the output power of the fuel cell and the storage battery in this time step according to the optimal working point.
[0005] However, in the traditional calculation method, the total equivalent hydrogen consumption of each working point needs to be calculated in one time step, which is a large amount of calculation. In addition, the maximum change rate of the output power of the fuel cell changes in real time with the state of the fuel cell itself and the environmental state, but the traditional calculation method does not consider the maximum change rate of the output power of the fuel cell (i.e., the maximum change amount of the output power of the fuel cell in one time step), and the next time output power of the fuel cell at the optimal working point calculated may be beyond the current maximum power change rate of the fuel cell, thereby wasting computing resources. SUMMARY
[0006] The present disclosure is based on providing an energy management method of a fuel cell hybrid vehicle to solve the above problems existing in the prior art.
[0007] Embodiments of this disclosure provide an energy management method for a fuel cell hybrid vehicle, the fuel cell hybrid vehicle including a fuel cell and a battery, the method comprising:
[0008] Determine the range of changes in the fuel cell's output power at the current time step relative to the previous time step.
[0009] Based on the equivalent hydrogen consumption theory, the optimal operating point is found from the operating points corresponding to the range of output power variation, and...
[0010] The output power of the fuel cell and battery is set according to the optimal operating point at the current time step.
[0011] Optionally, the midpoint of the output power variation range is the actual output power of the fuel cell in the previous time step.
[0012] Optionally, the two endpoints of the output power change range are the sum and difference between the actual output power of the fuel cell in the previous time step and the predicted output power change of the fuel cell in the current time step.
[0013] Specifically, the change in the output power of the fuel cell at the previous time step is adjusted based on the following four physical quantities to obtain the change in the output power of the fuel cell at the current time step:
[0014] Vehicle load at the current time step
[0015] Vehicle load at the previous time step
[0016] The expected output power of the fuel cell corresponding to the optimal operating point at the previous time step, and,
[0017] The actual output power of the fuel cell at the previous time step.
[0018] Optionally, if the vehicle load at the current time step is greater than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is increased based on the difference between the vehicle load at the current time step and the vehicle load at the previous time step, thereby obtaining the change in the output power of the fuel cell at the current time step.
[0019] Optionally, if the vehicle load at the current time step is less than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is reduced based on the difference between the vehicle load at the previous time step and the vehicle load at the current time step, thereby obtaining the change in the output power of the fuel cell at the current time step.
[0020] Optionally, if the actual output power of the fuel cell in the previous time step is less than the expected output power of the fuel cell in the previous time step, the change in output power of the fuel cell in the previous time step is reduced based on the difference between the expected output power and the actual output power in the previous time step, thereby obtaining the change in output power of the fuel cell in the current time step.
[0021] Optionally, based on the equivalent hydrogen consumption theory, finding the optimal operating point from the operating points corresponding to the range of output power variation includes:
[0022] From all operating points corresponding to the range of output power variation, select an operating point, and for each selected operating point, calculate the total equivalent hydrogen consumption of the fuel cell and the battery, and...
[0023] The operating point with the minimum total equivalent hydrogen consumption is selected as the optimal operating point.
[0024] Optionally, selecting an operating point from all operating points corresponding to the output power variation range includes any of the following: selecting an operating point randomly from all operating points corresponding to the output power variation range, and selecting an operating point with uniform output power variation intervals from all operating points corresponding to the output power variation range.
[0025] The energy management method for fuel cell hybrid vehicles disclosed herein has at least the following advantages:
[0026] In this disclosure, the range of output power change of the fuel cell relative to the previous time step is determined, and the optimal operating point is found from the operating points corresponding to the range of output power change based on the equivalent hydrogen consumption theory, thereby converging the calculation range. This allows for real-time correction of the dynamic characteristics of the fuel cell without having to calculate all possible power allocation operating points at each time step, thus reducing the amount of computation.
[0027] In this disclosure, the midpoint of the output power change range is the actual output power of the fuel cell in the previous time step, so that the output power of the fuel cell calculated each time is based on the actual output power of the fuel cell in the previous time step, thus avoiding sudden changes in the output power of the fuel cell.
[0028] In this disclosure, the change in the output power of the fuel cell in the previous time step is adjusted based on the vehicle load in the current time step, the vehicle load in the previous time step, the expected output power of the fuel cell corresponding to the optimal operating point in the previous time step, and the actual output power of the fuel cell in the previous time step. This yields the change in the output power of the fuel cell in the current time step. Furthermore, the endpoints of the output power change range are determined based on the change in the output power of the fuel cell in the current time step, thereby enabling a reasonable determination of the output power change range and improving the accuracy of finding the optimal operating point.
[0029] In this disclosure, when the vehicle load at the current time step is greater than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is increased based on the difference between the two to obtain the change in the output power of the fuel cell at the current time step. This further improves the accuracy of finding the optimal operating point and avoids limiting the maximum value of the rate of change of the fuel cell's output power.
[0030] In this disclosure, when the vehicle load at the current time step is less than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is reduced based on the difference between the two, thereby obtaining the change in the output power of the fuel cell at the current time step, which further improves the accuracy of finding the optimal operating point.
[0031] In this disclosure, when the actual output power of the fuel cell in the previous time step is less than the expected output power of the fuel cell in the previous time step, the change in output power of the fuel cell in the previous time step is reduced based on the difference between the two to obtain the change in output power of the fuel cell in the current time step. This ensures that the change in output power of the fuel cell in the current time step is achievable by the fuel cell, thereby avoiding the waste of computational resources. Attached Figure Description
[0032] Other details and advantages of this disclosure will become apparent from the detailed description provided below. It should be understood that the following figures are merely schematic and not drawn to scale, and therefore should not be considered as a limitation of this disclosure. A detailed description will follow with reference to the figures, in which:
[0033] Figure 1 A flowchart illustrating an energy management method for a fuel cell hybrid vehicle according to a specific embodiment of the present disclosure is shown schematically.
[0034] Figure 2A and 2BThe figures show graphs illustrating the relationship between the output power of a fuel cell under no-load and full-load conditions under both conventional and energy management methods according to a specific embodiment of the present disclosure.
[0035] Figure 3A and 3B The figures show graphs illustrating the relationship between the expected output power and actual output power of a fuel cell under no-load and full-load conditions, respectively, according to another specific embodiment of the present disclosure and employing the energy management method of the present disclosure. Detailed Implementation
[0036] Embodiments of this disclosure are described below with reference to the accompanying drawings. In the following description, numerous specific details are set forth to enable those skilled in the art to more fully understand and implement this disclosure. However, it will be apparent to those skilled in the art that implementations of this disclosure may not include some of these specific details. Furthermore, it should be understood that this disclosure is not limited to the specific embodiments described. Rather, this disclosure may be practiced with any combination of the features and elements described below, regardless of whether they relate to different embodiments. Therefore, the following aspects, features, embodiments, and advantages are for illustrative purposes only and should not be construed as elements or limitations of the claims unless expressly set forth in the claims.
[0037] Now refer to Figure 1 The diagram schematically illustrates a flowchart of an energy management method for a fuel cell hybrid vehicle according to a specific embodiment of this disclosure. Figure 1 As shown, the method includes the following steps:
[0038] Step S101: Determine the range of changes in the output power of the fuel cell at the current time step relative to the previous time step.
[0039] Specifically, the midpoint of the range of output power variation can be the actual output power of the fuel cell in the previous time step, so that the output power of the fuel cell calculated each time is based on the actual output power of the fuel cell in the previous time step, thus avoiding sudden changes in the output power of the fuel cell.
[0040] Furthermore, the two endpoints of the output power change range are the sum and difference of the actual output power of the fuel cell in the previous time step and the predicted output power change of the fuel cell in the current time step. The output power change of the fuel cell in the previous time step is adjusted based on the following four physical quantities to obtain the output power change of the fuel cell in the current time step: the vehicle load in the current time step, the vehicle load in the previous time step, the expected output power of the fuel cell corresponding to the optimal operating point in the previous time step, and the actual output power of the fuel cell in the previous time step. This allows for a reasonable determination of the output power change range, improving the accuracy of finding the optimal operating point.
[0041] More preferably, in order to avoid the maximum power change rate of the fuel cell constantly tightening, when the vehicle load at the current time step is greater than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is increased based on the difference between the vehicle load at the current time step and the vehicle load at the previous time step, thereby obtaining the change in the output power of the fuel cell at the current time step. This avoids limiting the maximum value of the fuel cell output power change rate and further improves the accuracy of finding the optimal operating point.
[0042] More preferably, when the vehicle load at the current time step is less than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is reduced based on the difference between the vehicle load at the previous time step and the vehicle load at the current time step, thereby obtaining the change in the output power of the fuel cell at the current time step. This allows for a reasonable determination of the range of output power changes and further improves the accuracy of finding the optimal operating point.
[0043] More preferably, if the actual output power of the fuel cell in the previous time step is less than the expected output power of the fuel cell in the previous time step, the change in output power of the fuel cell in the previous time step is reduced based on the difference between the expected output power and the actual output power in the previous time step, thereby obtaining the change in output power of the fuel cell in the current time step. This ensures that the change in output power of the fuel cell in the current time step is achievable by the fuel cell, thus avoiding the waste of computational resources.
[0044] Step S102: Based on the equivalent hydrogen consumption theory, find the optimal operating point from the operating points corresponding to the range of output power changes.
[0045] Specifically, firstly, a suitable operating point can be selected from all operating points corresponding to the output power variation range. Then, the total equivalent hydrogen consumption of the fuel cell and battery is calculated for each selected operating point. Finally, the operating point with the minimum total equivalent hydrogen consumption is selected as the optimal operating point. Those skilled in the art will understand that the selected operating point can be chosen randomly from all operating points corresponding to the output power variation range, or it can be selected according to a set rule. For example, operating points can be selected from all operating points corresponding to the output power variation range at uniform output power variation intervals. These variations do not exceed the protection scope of this disclosure. Furthermore, the number of selected operating points can also be set according to actual conditions; these variations do not exceed the protection scope of this disclosure.
[0046] Those skilled in the art will understand that the total equivalent hydrogen consumption of the fuel cell and battery at the selected operating point can be calculated using any suitable known method, and these variations do not exceed the scope of this disclosure. For example, the total equivalent hydrogen consumption of the fuel cell and battery can be calculated based on an energy management model established according to the equivalent hydrogen consumption theory, which may include the following equations:
[0047] Fuel total =Fuel FC +K×Fuel BAT
[0048]
[0049] Among them, Fuel total For the total instantaneous hydrogen consumption of a fuel cell hybrid vehicle, Fuel FC For the instantaneous hydrogen consumption of fuel cells, Fuel BAT The instantaneous equivalent hydrogen consumption of the battery is given by K, where K is the hydrogen-electric equivalence coefficient, a is the equivalent hydrogen consumption factor, and SOC is the state of charge. H The SOC is the upper limit of the desired battery's state of charge range. L This represents the lower limit of the desired operating state of charge range for the battery. The equivalent hydrogen consumption factor 'a' can be a fixed value or a variable value.
[0050] Furthermore, the energy management model may also include the following equations:
[0051] Fuel FC =A×P FC +B
[0052]
[0053] n dis =C1×BAT SOC 3 +D1*BATSOC 2 +E1*BAT SOC +F1
[0054] n chg =C2×BAT SOC 3 +D2*BAT SOC 2 +E2*BAT SOC +F2
[0055] Among them, P FC P represents the output power of the fuel cell. BAT P is the output power of the battery. fc_avg The average power of the fuel cell, Fuel fc_avg Let n be the average instantaneous hydrogen consumption of the fuel cell. dis For the discharge efficiency of the battery, n chg The charging efficiency of the battery is represented by A, B, C1, C2, D1, D2, E1, E2, F1, and F2, which are values obtained by fitting the test data of the fuel cell and the battery, respectively.
[0056] Step S103: Set the output power of the fuel cell and battery at the current time step according to the optimal operating point.
[0057] By using the method proposed in this disclosure, it is not necessary to calculate all possible operating points at each time step, thereby reducing the amount of computation.
[0058] Figure 2A and 2B The figures show graphs illustrating the relationship between the output power of a fuel cell under no-load and full-load conditions under both conventional and energy management methods according to a specific embodiment of the present disclosure.
[0059] Figure 2A and 2B In the diagram, the green line represents changes in vehicle load, the blue line represents changes in fuel cell output power obtained using conventional energy management methods, and the red line represents changes in fuel cell output power obtained using the energy management method of this disclosure. Figure 2A and Figure 2B It can be clearly seen from the above that, whether in no-load condition ( Figure 2A (or full load condition) Figure 2B Compared with traditional energy management methods, the energy management method disclosed herein provides a more stable output power for fuel cells, avoiding sudden changes in the output power of fuel cells and thus extending the service life of fuel cells.
[0060] Figure 3A and 3B The figures show graphs illustrating the relationship between the expected output power and actual output power of a fuel cell under no-load and full-load conditions, respectively, according to another specific embodiment of the present disclosure and employing the energy management method of the present disclosure.
[0061] from Figure 3A and Figure 3B It can be clearly seen from the above that, whether in no-load condition ( Figure 3A (or full load condition) Figure 3B The actual output power of the fuel cell and its expected output power show good consistency, ensuring that the expected output power is achievable. Furthermore, due to the hydrogen-electric equivalence coefficient, while preventing sudden changes in the fuel cell's output power, the battery's state of charge remains stable within its operating range.
[0062] In this disclosure, fuel cell hybrid vehicles can be not only traditional vehicles, such as cars and trucks, but also construction machinery that can operate in mining areas, such as excavators, bulldozers, cranes, and road rollers.
[0063] Industrial applicability
[0064] In this disclosure, the range of output power change of the fuel cell relative to the previous time step is determined, and the optimal operating point is found from the operating points corresponding to the range of output power change based on the equivalent hydrogen consumption theory, thereby converging the calculation range. This allows for real-time correction of the dynamic characteristics of the fuel cell without having to calculate all possible power allocation operating points at each time step, thus reducing the amount of computation.
[0065] In this disclosure, the midpoint of the output power change range is the actual output power of the fuel cell in the previous time step, so that the output power of the fuel cell calculated each time is based on the actual output power of the fuel cell in the previous time step, thus avoiding sudden changes in the output power of the fuel cell.
[0066] In this disclosure, the change in the output power of the fuel cell in the previous time step is adjusted based on the vehicle load in the current time step, the vehicle load in the previous time step, the expected output power of the fuel cell corresponding to the optimal operating point in the previous time step, and the actual output power of the fuel cell in the previous time step. This yields the change in the output power of the fuel cell in the current time step. Furthermore, the endpoints of the output power change range are determined based on the change in the output power of the fuel cell in the current time step, thereby enabling a reasonable determination of the output power change range and improving the accuracy of finding the optimal operating point.
[0067] In this disclosure, when the vehicle load at the current time step is greater than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is increased based on the difference between the two to obtain the change in the output power of the fuel cell at the current time step. This further improves the accuracy of finding the optimal operating point and avoids limiting the maximum value of the rate of change of the fuel cell's output power.
[0068] In this disclosure, when the vehicle load at the current time step is less than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is reduced based on the difference between the two, thereby obtaining the change in the output power of the fuel cell at the current time step, which further improves the accuracy of finding the optimal operating point.
[0069] In this disclosure, when the actual output power of the fuel cell in the previous time step is less than the expected output power of the fuel cell in the previous time step, the change in output power of the fuel cell in the previous time step is reduced based on the difference between the two to obtain the change in output power of the fuel cell in the current time step. This ensures that the change in output power of the fuel cell in the current time step is achievable by the fuel cell, thereby avoiding the waste of computational resources.
[0070] While this disclosure has been described above with reference to preferred embodiments, it is not limited thereto. Any modifications and alterations made by those skilled in the art without departing from the spirit and scope of this disclosure should be included within the scope of protection of this disclosure. Therefore, the scope of protection of this disclosure should be determined by the scope defined in the claims.
Claims
1. An energy management method for a fuel cell hybrid vehicle, the fuel cell hybrid vehicle comprising a fuel cell and a battery, characterized in that, The method includes: Determine the range of changes in the fuel cell's output power at the current time step relative to the previous time step. Based on the equivalent hydrogen consumption theory, the optimal operating point is found from the operating points corresponding to the range of output power variation, and... The output power of the fuel cell and battery is set according to the optimal operating point at the current time step.
2. The energy management method according to claim 1, wherein, The midpoint of the range of output power variation is the actual output power of the fuel cell in the previous time step.
3. The energy management method according to claim 2, wherein, The two endpoints of the output power change range are the sum and difference between the actual output power of the fuel cell at the previous time step and the predicted output power change of the fuel cell at the current time step. Specifically, the change in the output power of the fuel cell at the previous time step is adjusted based on the following four physical quantities to obtain the change in the output power of the fuel cell at the current time step: Vehicle load at the current time step Vehicle load at the previous time step The expected output power of the fuel cell corresponding to the optimal operating point at the previous time step, and, The actual output power of the fuel cell at the previous time step.
4. The energy management method according to claim 3, wherein, If the vehicle load at the current time step is greater than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is increased based on the difference between the vehicle load at the current time step and the vehicle load at the previous time step, thereby obtaining the change in the output power of the fuel cell at the current time step.
5. The energy management method according to claim 3, wherein, If the vehicle load at the current time step is less than the vehicle load at the previous time step, the change in the output power of the fuel cell at the previous time step is reduced based on the difference between the vehicle load at the previous time step and the vehicle load at the current time step, thereby obtaining the change in the output power of the fuel cell at the current time step.
6. The energy management method according to claim 3, wherein, If the actual output power of the fuel cell in the previous time step is less than the expected output power of the fuel cell in the previous time step, the change in output power of the fuel cell in the previous time step is reduced based on the difference between the expected output power and the actual output power in the previous time step, thereby obtaining the change in output power of the fuel cell in the current time step.
7. The energy management method according to claim 1, wherein, Based on the equivalent hydrogen consumption theory, finding the optimal operating point from the operating points corresponding to the range of output power variation includes: Select an operating point from all operating points corresponding to the range of output power variation. For each selected operating point, the total equivalent hydrogen consumption of the fuel cell and the battery is calculated, and the operating point with the minimum total equivalent hydrogen consumption is selected as the optimal operating point.
8. The energy management method according to claim 7, wherein, The operating point selected from all operating points corresponding to the range of output power variation includes any of the following: The operating point is selected randomly from all operating points corresponding to the range of output power variation, and, Among all operating points corresponding to the output power variation range, operating points are selected at uniform intervals of output power variation.