A method and apparatus for uphill energy management and downhill energy management of fuel cell vehicles.

Abstract

This invention belongs to the field of new energy vehicle technology, specifically relating to an uphill energy management method, a downhill energy management method, and a device for fuel cell vehicles. When a vehicle is operating on a straight road section and enters a long uphill or downhill section, the method calculates the amount of electricity that needs to be replenished or consumed before the power battery reaches its target SOC value at the starting point of the long downhill. This determines the shortest distance on the straight road section required for the power battery to be replenished or discharged before entering the uphill or downhill section. Within the area covering this shortest distance before entering the long uphill or downhill section, the power battery SOC is pre-charged to a high level or depleted to a low level. During the uphill or downhill process, the target power of the fuel cell is controlled according to relevant parameters. This solves the problem of insufficient vehicle power due to a depleted power battery on a long uphill section or braking failure due to an overcharged battery on a long downhill section. It achieves precise control of fuel cell heavy-duty trucks in mountainous conditions, improving the overall vehicle economy.

Description

Technical Field

[0001] This invention belongs to the field of new energy vehicle technology, specifically relating to an uphill energy management method, a downhill energy management method, and a device for fuel cell vehicles. Background Technology

[0002] Hydrogen energy, as a clean, renewable, and storable secondary energy source, is an important measure for addressing climate change and environmental pollution, and ensuring sustainable energy development. Fuel cell heavy-duty commercial vehicles, with their short refueling time and long driving range, can meet the demands of heavy-duty, long-range operation, and are a crucial support for building a clean, low-carbon transportation system and a safe and efficient energy system.

[0003] Currently, most fuel cell heavy-duty commercial vehicles in China adopt a power system solution of "medium-power fuel cell + small-capacity power battery". For example, Chinese patent CN116022035B discloses a power system, energy control method and device for a fuel cell heavy-duty truck. It adopts a multi-mode fuel cell energy management strategy based on multiple rules constrained by the vehicle's power battery SOC, vehicle start-stop, and operating condition requirements. It sets corresponding compensation power according to the vehicle model and actual SOC, which improves the working efficiency of the fuel cell system and enhances the vehicle's power and economy. This patent is only applicable when the fuel cell output power can cover the average power of the entire vehicle. However, with the vigorous promotion of fuel cell heavy-duty commercial vehicles, the application scenarios of fuel cell heavy-duty commercial vehicles are constantly expanding, from short-distance trips within the factory and around the city to cross-city and cross-province transportation. This makes the load range of fuel cell heavy-duty commercial vehicles vary greatly and the operating conditions more diverse and complex, resulting in large fluctuations in the power demand of the entire vehicle. Especially during operation in mountainous conditions, fuel cell heavy-duty trucks, when fully loaded and traveling uphill on long slopes, require an average power demand of over 300kW. Currently, the power output of fuel cells cannot meet this demand, leading to a risk of battery depletion and insufficient vehicle power. Conversely, when fully loaded and traveling downhill on long slopes, the continuous use of electric braking regenerative braking can easily cause the battery to fully charge, resulting in the loss of electric braking, increased air brake load, and ultimately, brake failure. To address this, existing technologies propose strategies such as active battery energy storage before uphill driving and high-power battery release before downhill driving. However, they lack specific and effective implementation methods, failing to precisely control the power system of fuel cell heavy-duty commercial vehicles operating in mountainous conditions to solve the problems of insufficient vehicle power due to battery depletion uphill or electric braking failure due to overcharged battery downhill. Summary of the Invention

[0004] The purpose of this invention is to provide an uphill energy management method, a downhill energy management method, and a device for fuel cell vehicles, in order to solve the problems of insufficient vehicle power due to battery depletion on uphill runs or electric braking failure due to overcharged battery on downhill runs when fuel cell vehicles are operating in mountainous areas.

[0005] To solve the above-mentioned technical problems, the present invention provides an uphill energy management method for fuel cell vehicles, comprising: when the vehicle is operating from a straight road section to a long uphill section, determining the current state of power battery depletion with the goal of the power battery reaching a first set value at the starting point of the long uphill section; determining the shortest length on the straight road section required to recharge the power battery before going uphill based on the state of power battery depletion; and defining the area on the straight road section before entering the long uphill section that covers the shortest length as the uphill buffer area.

[0006] Within the buffer zone before the uphill climb, the target power of the fuel cell within the buffer zone is determined based on the vehicle's current SOC and the calibrated relationship between the SOC of the power battery and the target power of the fuel cell.

[0007] During the uphill process, if the throttle opening is not at its maximum, the target power of the fuel cell during the uphill process is determined based on the average power of the vehicle, the length of the slope, the climbing speed, the current SOC of the power battery, and the lower limit of the allowable SOC of the power battery, using the first set time as the cycle.

[0008] The operation of the fuel cell is controlled according to the determined target power of the fuel cell.

[0009] Furthermore, the calibration process is as follows: the SOC of the power battery is divided into N segments based on the balanced SOC of the power battery, and a calibration experiment is performed on each segment to determine the target power of the fuel cell corresponding to each segment. The SOC corresponding to the first segment is less than the balanced SOC of the power battery, and the SOC corresponding to the remaining segments increases sequentially based on the balanced SOC of the power battery until the upper limit of the power battery charging is reached; N≥3.

[0010] Furthermore, during the uphill process, the target power of the fuel cell is the target power optimized based on a correction coefficient; the correction coefficient is calibrated according to the rate of change of the SOC of the power battery within the first set period. When the rate of change of the SOC of the power battery is large, the correction coefficient is greater than 1; when the rate of change of the SOC of the power battery is small, the correction coefficient is less than 1.

[0011] Furthermore, during the uphill process, when the throttle opening reaches its maximum, the fuel cell target power is applied to the rated power at the fastest load change rate.

[0012] Furthermore, the shortest length on a straight road section required to recharge the power battery before going uphill is calculated using the following formula:

[0013]

[0014] Among them, L uf The minimum length required to recharge the power battery; SOC1 is the first set value. current For the current SOC of the power battery, E b For the rated capacity of the power battery, u f For the commonly used speed on straight roads, P efc For the rated power of the fuel cell, P fv This represents the average power of vehicles on straight road sections.

[0015] Furthermore, the long uphill section refers to a section where the length of a continuous uphill slope is greater than a first threshold, and the formula for calculating the first threshold is:

[0016]

[0017] Among them, L u As the first threshold, SOC b To balance the SOC of the power battery, SOC a E is the lower limit of power battery discharge. b For the rated capacity of the power battery, u i For the speed of the vehicle climbing the hill, P iv P represents the average power output for the entire vehicle when climbing hills. efc This refers to the rated power of the fuel cell.

[0018] Furthermore, when vehicles are running on a fixed route, electronic fences are used to monitor whether vehicles enter the buffer zone before an uphill section or the uphill section.

[0019] The beneficial effects of the above technical solution are as follows: This invention is a pioneering invention. When the vehicle is operating on a long uphill section that may lead to battery depletion when entering from a straight section, the invention pre-calculates the degree of battery depletion when the SOC of the power battery reaches a large first set value at the starting point of the long uphill section. Based on the degree of battery depletion, the invention determines the shortest distance on the straight section to recharge the power battery before entering the uphill section. Within the buffer zone covering the shortest length of the straight section before entering the long uphill section, the target power of the fuel cell is adjusted according to the current SOC to ensure that the power battery SOC is charged to a high level before the vehicle enters the uphill section. Furthermore, during the uphill process, the target power of the fuel cell is continuously updated periodically based on the real-time current SOC and the lower limit of the power battery to avoid the power battery consuming too much power during the uphill process. By pre-adjusting the energy distribution rules of the fuel cell under long uphill conditions, the target power of the fuel cell is precisely controlled, solving the problem of insufficient power of the vehicle due to battery depletion during long uphill sections, and broadening the application scenarios of fuel cell heavy-duty trucks in mountainous conditions.

[0020] To address the aforementioned technical problems, the present invention also provides a downhill energy management method for fuel cell vehicles, comprising:

[0021] When the vehicle is operating from a straight road section to a long downhill section, the power battery’s current power consumption is determined with the goal of the power battery’s SOC reaching a second set value at the starting point of the long downhill. Based on the power consumption, the shortest length on the straight road section required for the power battery to consume power before the downhill is determined. The area on the straight road section that covers the shortest length before entering the long downhill section is recorded as the buffer area before the downhill.

[0022] Within the buffer zone before the downhill slope, the target power of the fuel cell is determined based on the current SOC of the power battery, the second set value, and the average power of the vehicle in the previous cycle, using the second set time as the cycle.

[0023] During downhill driving, when the current SOC of the power battery is less than or equal to the third set value, the target power of the fuel cell is the idle power; when the current SOC of the power battery is greater than the third set value, the fuel cell shuts down.

[0024] The operation of the fuel cell is controlled according to the determined target power of the fuel cell.

[0025] Furthermore, the formula for calculating the target power of the fuel cell within the buffer zone before the downhill slope is as follows:

[0026]

[0027] Among them, P fv_pre__Dtarget For the target power of the fuel cell in the buffer zone before the downhill slope, SOC current The current SOC of the power battery is given by P, and SOC2 is the second set value. fc This represents the vehicle's average power during the previous cycle.

[0028] Furthermore, the long downhill section refers to a section where the elevation difference during continuous downhill descent exceeds the second threshold. The formula for calculating the second threshold is:

[0029]

[0030] Among them, SOC c The upper limit of power battery charging, SOC b To balance the SOC of the power battery, E b The rated capacity of the power battery is m v Let g be the total mass of the vehicle and its cargo, g be the acceleration due to gravity, and η be the total mass of the vehicle and its cargo. e This is the coefficient for converting gravitational potential energy into electrical energy.

[0031] The beneficial effects of the above technical solution are as follows: This invention is a pioneering invention. When the vehicle is operating on a long downhill section where it may become overcharged due to entering from a straight section, the invention pre-calculates the amount of electricity required for the power battery to reach a lower SOC value at the starting point of the long downhill section. Based on the amount of electricity consumed, the shortest length of the power battery discharge on the straight section before the downhill is determined. Within the buffer zone covering the shortest length of the straight section before entering the long downhill section, the target power of the fuel cell is continuously updated periodically to deplete the power battery SOC to a low level before the downhill, freeing up power battery capacity for downhill braking energy recovery. After the vehicle begins to descend the slope, the fuel cell is placed in idle mode. When the power battery SOC exceeds the upper limit, the fuel cell is shut down. By pre-adjusting the fuel cell energy distribution rules under long downhill conditions, the target power of the fuel cell is precisely controlled, solving the problem of braking failure caused by an overcharged power battery during long downhill sections. This expands the application scenarios of fuel cell heavy-duty trucks in mountainous conditions.

[0032] To address the aforementioned technical problems, the present invention also provides a hill-climb energy management device for fuel cell vehicles, comprising a processor for executing computer program instructions to implement the steps in the hill-climb energy management method for fuel cell vehicles described above.

[0033] To address the aforementioned technical problems, the present invention also provides a downhill energy management device for fuel cell vehicles, comprising a processor for executing computer program instructions to implement the steps in the downhill energy management method for fuel cell vehicles described above.

[0034] The beneficial effects of the above technical solution are as follows: This invention is a pioneering invention. When the vehicle is operating on a long downhill section where it may become overcharged due to entering from a straight section, the invention pre-calculates the amount of electricity required for the power battery to reach a lower SOC value at the starting point of the long downhill section. Based on the amount of electricity consumed, the shortest length of the power battery discharge on the straight section before the downhill is determined. Within the buffer zone covering the shortest length of the straight section before entering the long downhill section, the target power of the fuel cell is continuously updated periodically to deplete the power battery SOC to a low level before the downhill, freeing up power battery capacity for downhill braking energy recovery. After the vehicle begins to descend the slope, the fuel cell is placed in idle mode. When the power battery SOC exceeds the upper limit, the fuel cell is shut down. By pre-adjusting the fuel cell energy distribution rules under long downhill conditions, the target power of the fuel cell is precisely controlled, solving the problem of braking failure caused by an overcharged power battery during long downhill sections. This expands the application scenarios of fuel cell heavy-duty trucks in mountainous conditions. Attached Figure Description

[0035] Figure 1This is a schematic diagram of the power system of an embodiment of the uphill energy management method of the present invention;

[0036] Figure 2 This is a schematic diagram illustrating the uphill energy management principle of an embodiment of the uphill energy management method of the present invention;

[0037] Figure 3 This is a schematic diagram of an embodiment of the uphill energy management method of the present invention based on electronic fence energy management;

[0038] Figure 4 This is a schematic diagram of the SOC trend in an embodiment of the uphill energy management method of the present invention;

[0039] Figure 5 This is a schematic diagram of the device connection in an embodiment of the uphill energy management device of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the present invention clearer, the specific embodiments of the present invention will be further described below with reference to the accompanying drawings.

[0041] This invention addresses the problem of excessive DOD (Depth of Discharge) in existing fuel cell heavy-duty commercial vehicle power systems during mountainous operation. Specifically, this leads to electric braking failure due to a depleted battery going uphill or a fully charged battery going downhill. Based on the current state of fuel cell system development, this invention designs a range-extended power system solution consisting of a "medium-power fuel cell system + high-capacity energy-type power battery." The system identifies long uphill or downhill sections, as well as straight sections, based on future road changes under the vehicle's operating conditions. When the vehicle transitions from a straight section to a long uphill or downhill section, the current distance to the power battery is calculated. The system determines the amount of electricity that needs to be replenished or consumed when the State of Charge (SOC) reaches the target value at the starting point of a long downhill slope. This allows for the determination of the shortest length for the power battery to be recharged or discharged before going uphill or downhill. Within a region exceeding this shortest length before going uphill or downhill, the power battery's SOC is pre-charged to a high level or depleted to a low level. During the uphill or downhill process, the target power of the fuel cell is controlled according to relevant parameters. This solves the problem of insufficient vehicle power due to a depleted power battery during long uphill slopes or brake failure due to an overcharged battery during long downhill slopes. It enables precise control of fuel cell heavy-duty trucks in mountainous conditions and improves the overall vehicle economy.

[0042] Uphill Energy Management Method Implementation Examples

[0043] The power system of a fuel cell heavy-duty commercial vehicle includes a fuel cell, a dedicated fuel cell DC-DC converter, a power battery, a hydrogen system, a drive motor, a five-in-one controller, a transmission, a vehicle control unit (VCU), and controllers for various components. The fuel cell's rated power meets the average power requirements of the entire vehicle. The dedicated fuel cell DC-DC converter's output terminal contains a current sensor. The power battery's capacity is more than twice the fuel cell's rated power, and the power battery's peak power is not less than the drive motor's peak power. Simultaneously, the fuel cell, hydrogen system, power battery, and drive motor are controlled by the vehicle control unit. Furthermore, such as... Figure 1 As shown, the fuel cell and the dedicated DC-DC converter of the fuel cell heavy commercial vehicle power system are fixedly connected as one unit. The power battery BMS and the motor controller are integrated into an eight-in-one controller. The fuel cell and the eight-in-one controller are connected through high voltage. The power system controls the power output of the fuel cell system and the output torque of the drive motor, so as to make the output power of the fuel cell system and the state of charge of the power battery adaptable to the working conditions in mountainous areas, thereby expanding the application scenarios of the fuel cell vehicle and improving the economy of the vehicle.

[0044] To achieve optimal operating efficiency and good adaptability to various operating conditions, the power system employs a predictive fuel cell energy management strategy based on global planning encompassing gyroscopes, accelerometers, high-precision navigation maps, slope recognition modules, remote monitoring systems, and operating condition requirements. For example... Figure 2 As shown, the present invention provides a method for uphill energy management of a fuel cell vehicle, including energy management before uphill and energy management during uphill, which will be described in detail below.

[0045] 1. Identify straight road sections and long uphill sections under vehicle operating conditions.

[0046] For fixed operating routes, road spectrum data is collected. Based on this data, the route elevation is analyzed to identify straight sections and long uphill sections under vehicle operating conditions. Uphill areas are then delineated on an electronic map. Long uphill sections are defined as sections with continuous uphill slopes exceeding a first threshold. The first threshold is determined based on road gradient, battery capacity, system state of charge (SOC), and climbing speed, and is calculated as follows:

[0047]

[0048] Among them, L u The first threshold is expressed in km; SOC b The SOC (State of Charge) of the power battery refers to the target SOC value of the power battery at which the fuel cell power system operates in its optimal state. a This is the lower limit of power battery discharge, typically taken as 0.08-0.1; E b The rated capacity of the power battery is expressed in kWh; ui P represents the vehicle speed while climbing the hill, in km / h. iv P represents the vehicle's average power output for hill climbing, measured in kW. efc Rated power of fuel cell, in kW; η T For mechanical power transmission efficiency; m v The total mass of the vehicle and cargo is expressed in kg; g is the acceleration due to gravity, expressed in m / s². 2 f is the rolling resistance coefficient; α i For the average slope angle of a continuous uphill slope, α i =tan -1 (i u ), i u Road slope; u i C represents the speed at which the vehicle climbs the hill, in km / h. D A is the drag coefficient; A is the frontal area, in m². 2 .

[0049] For non-fixed routes, vehicles are equipped with navigation maps, GPS positioning devices, acceleration sensors, and slope recognition modules. Before departure, the VCU reads the mileage and altitude information from the slope recognition module for the entire journey from the departure point to the destination, calculates the total slope data i(L), and uses the VCU to filter out uphill slopes greater than the slope threshold and continuous slope lengths greater than L. u For sections of road with long uphill sections, mark the starting mileage of the slope as L. u0 Theoretically, when i(L) > 0, it is an uphill slope, and when i(L) < 0, it is a downhill slope. Preferably, in this embodiment, the uphill section with a gradient greater than a gradient threshold is considered an uphill section. The gradient threshold can be set according to actual working conditions, such as 2%, 3%, or 4%. In this embodiment, it is set to 3%. The formula for calculating i(L) is as follows:

[0050]

[0051] Wherein, ΔH is the elevation difference of a distance ΔL, in meters; ΔL is in kilometers, and is calibrated in conjunction with the vehicle's remaining driving range, generally taken as 1-5 kilometers.

[0052] 2. Determine the buffer zone before the uphill section where the power battery is recharged.

[0053] This invention sets a higher target SOC before uphill driving and adjusts the target power of the fuel cell within a buffer zone before uphill driving to ensure that the vehicle's power battery SOC is charged to a high level before ascending the hill. The process of determining the buffer zone before uphill driving is as follows:

[0054] When a vehicle transitions from a straight road section to a long uphill section, the battery's state of charge (SOC) is determined with the goal of reaching a first set value at the start of the uphill. Based on this depletion, the shortest distance on the straight road section required to recharge the battery before the uphill is determined. The area on the straight road section covering this shortest distance before entering the long uphill is designated as the pre-uphill buffer zone. The shortest distance on the straight road section required to recharge the battery before the uphill is calculated using the following formula:

[0055]

[0056] Among them, L uf The minimum length required to recharge the power battery; SOC1 is the first set value. current For the current SOC of the power battery, E b For the rated capacity of the power battery, u f For the commonly used speed on straight roads, P efc For the rated power of the fuel cell, P fv This represents the average power output of vehicles on straight road sections. The initial setting is determined based on actual conditions and can be set as the upper limit for battery charging. That is:

[0057]

[0058] Among them, SOC c The upper limit for charging power batteries is generally set at 0.90-0.98.

[0059] 3. Uphill energy management.

[0060] This includes energy management strategies before and during the uphill climb, controlling fuel cell operation based on the determined target power. After identifying the pre-uphill buffer zone, a geofence-based fuel cell energy management strategy is employed for fixed operating routes, monitoring whether vehicles enter the pre-uphill buffer zone or the uphill section based on the geofence. For example... Figure 3 As shown, three electronic fence zones are drawn on the electronic map of the vehicle-mounted ICARD remote monitoring system, namely areas A, B, and C. Area B is a buffer zone before the uphill slope, covering a road length greater than L. uf Area C is the uphill area, covering the entire uphill section. Area A is used to identify the vehicle's direction of travel. When the vehicle enters the long uphill section from a straight section (i.e., after entering Area B from Area A), the pre-uphill energy management strategy of the fuel cell is triggered. When the vehicle enters Area C from Area B, the uphill energy management strategy is triggered. When the vehicle leaves Area C and travels on a straight section, the uphill energy management strategy is discontinued, and a semi-following energy management strategy is automatically switched. The SOC trend of the power battery is as follows: Figure 4 As shown.

[0061] When the vehicle's route is not fixed, when the vehicle's mileage reaches S=L u0 -L uf When the vehicle's mileage reaches S=L, the VCU switches to the pre-uphill energy management strategy; u0 When the VCU switches to an uphill energy management strategy; when S≥L u0 +L u Furthermore, when the VCU determines that the average slope ahead is less than 1%, it exits the energy management strategy during the uphill process and automatically switches to the semi-following energy management strategy, that is, the output power of the fuel cell system is the average power of the vehicle in the previous period.

[0062] 1) Energy management strategies before going uphill.

[0063] Within the buffer zone before the uphill climb, the target power of the fuel cell is determined based on the vehicle's current SOC and the calibrated relationship between the power battery SOC and the fuel cell target power. This invention employs a fixed-point operating mode for the fuel cell within the buffer zone before the uphill climb. Fixed-point operating refers to the fuel cell system output power at a series of set power points. The calibration process is as follows: the power battery SOC is divided into N segments based on the power battery's balanced SOC. Calibration experiments are performed on each segment to determine the corresponding target power of the fuel cell. The SOC corresponding to the first segment is less than the power battery's balanced SOC, and the SOCs of the remaining segments increase sequentially based on the power battery's balanced SOC until the power battery's charging upper limit is reached; N ≥ 3. For example, if N is set to 6, six operating points are set for the fuel cell target power within the buffer zone. The fuel cell target power is calibrated according to the SOC range and operating condition characteristics, as shown in Table 1.

[0064] P fv_pre__Utarget =P fc (SOC)

[0065] Table 1

[0066] <![CDATA[SOC current ]]> <![CDATA[≤SOC b ]]> <![CDATA[≤SOC b +0.1]]> <![CDATA[SOC b +0.2]]> <![CDATA[SOC b +0.3]]> ≥90％ ≥98％ <![CDATA[P fv_pre__Utarget ]]> <![CDATA[P efc ]]> <![CDATA[P efc *0.8]]> <![CDATA[P efc *0.6]]> <![CDATA[P efc *0.3]]> <![CDATA[P fc_Idle ]]> 0

[0067] Among them, P fv_pre__Utarget P represents the target power of the fuel cell within the buffer zone before the uphill climb, in kW. fc_Id1e This refers to the fuel cell's idle power, measured in kW. For operating conditions in plains areas, the SOC (State of Charge) is... bGenerally, a value of 0.5 is used, but for mountainous roads, a value between 0.6 and 0.9 is taken. The target fuel cell power corresponding to each segment in the table above is obtained through actual vehicle testing based on the vehicle's configured power battery rated capacity, fuel cell rated power, and user requirements. There are no restrictions here, and the target fuel cell power obtained from testing different vehicle configurations may differ. For example, if the vehicle's configured power battery rated capacity is 262kWh and the fuel cell system rated power is 130kW, when the vehicle's current SOC is less than the power battery's balanced SOC (the first interval in the table), the fuel cell is controlled to operate at its rated power to quickly charge the power battery to the target SOC. When the vehicle's current SOC is in the second interval in the table, it can be seen that the battery SOC is 0.1 higher than the SOC in the first interval. At this point, it can be approximated as 1 - battery rated capacity * 0.1 / P. efc The estimated calibration coefficient is 262 * 0.1 / 130 = 0.202. Retaining one significant figure, we take 0.2, so the calibration coefficient is 1 - 0.2 = 0.8. When the current SOC is high, for example, when the current SOC ≥ 0.8 (the current SOC is in the fourth interval or later), considering the overall vehicle economy, the calibration coefficient can be reduced.

[0068] 2) Energy management strategies during uphill climbs.

[0069] During the uphill climb, when the throttle opening is not at its maximum, the target power of the fuel cell is determined based on the vehicle's average power, slope length, climbing speed, current SOC of the power battery, and the lower limit of the power battery's allowable SOC, using a first set time period as the cycle. The first set time can be set according to requirements, for example, within 1-5 minutes. The calculation formula is:

[0070]

[0071] Among them, P fv_on__Utarget For the target power of the fuel cell during the uphill process, L u ′ represents the actual slope length.

[0072] Preferably, to achieve more precise control, the target power of the fuel cell during the uphill process is an optimized target power based on a correction coefficient. This correction coefficient is calibrated according to the rate of change of the power battery's SOC within the first set period. When the rate of change of the power battery's SOC is large, the correction coefficient is greater than 1; when the rate of change of the power battery's SOC is small, the correction coefficient is less than 1. The calculation formula is as follows:

[0073]

[0074] Where μ is the correction coefficient. When SOC decreases rapidly, μ > 1.0, and when SOC decreases slowly, μ < 1.0. ΔSOC is the change in SOC within the calculation period, which satisfies the vehicle's power requirements while also taking into account the vehicle's economy.

[0075] During the uphill process, when the throttle opening reaches its maximum, that is, after the VCU detects full throttle, the fuel cell target power is loaded to the rated power at the fastest load change rate. After the full throttle is released, the fuel cell target power is executed according to the original strategy mentioned above.

[0076] Examples of downhill energy management methods

[0077] The downhill energy management method for a fuel cell vehicle of the present invention uses the same power system as the uphill energy management method embodiment, and will not be described again here. The downhill energy management method includes energy management before downhill and energy management during downhill, which will be described in detail below.

[0078] 1. Identify straight road sections and long downhill sections under vehicle operating conditions.

[0079] For fixed operating routes, road spectrum data is collected. Based on this data, the route elevation is analyzed to identify straight sections and long downhill sections suitable for vehicle operation. Downhill areas are then delineated on an electronic map. Long downhill sections are defined as sections with a continuous elevation difference exceeding a second threshold. The formula for calculating the second threshold is:

[0080]

[0081] Among them, H d The second threshold is in meters; η e This is the coefficient for converting gravitational potential energy into electrical energy, which is empirically taken as 0.4-0.6.

[0082] For non-fixed routes, vehicles are equipped with navigation maps, GPS positioning devices, acceleration sensors, and slope recognition modules. Before departure, the VCU reads the mileage and altitude information from the slope recognition module for the entire journey from the departure point to the destination, calculates the total slope data i(L), and identifies downhill sections with a slope greater than a slope threshold as downhill sections. The VCU then filters out downhill sections with a slope greater than the slope threshold and a continuous elevation difference greater than H. d The section of road is marked with the starting mileage of the downhill section as L. d0 .

[0083] 2. Determine the buffer zone before the downhill slope required for the power battery to consume power.

[0084] This invention sets a lower target SOC before descending a slope and adjusts the target power of the fuel cell within a buffer zone before the descent to ensure that the vehicle depletes the battery's SOC to a low level before descending. The process of determining the buffer zone before descending is similar to that before ascending. When the vehicle is transitioning from a straight road section to a long downhill section, the required power consumption of the battery is determined with the target SOC at the start of the long downhill as a second set value. Based on the power consumption, the shortest length on the straight road section required for the battery to deplete its power before descending is determined. The area covering this shortest length on the straight road section before entering the long downhill section is designated as the buffer zone before descending. The shortest length on the straight road section required for the battery to deplete its power before descending is calculated using the following formula:

[0085]

[0086] Among them, L df SOC2 is the second set value, representing the minimum length required for the power battery to consume power. This second set value is set according to requirements; in this embodiment, it is 0.2.

[0087] 3. Downhill energy management.

[0088] This includes pre-descent energy management strategies and in-descent energy management strategies, controlling fuel cell operation based on the determined target power. After determining the pre-descent buffer zone, for fixed operating routes, an electronic fence-based fuel cell energy management strategy is adopted. This strategy monitors whether vehicles enter the pre-descent buffer zone or the downhill section based on the electronic fence. The method for defining the downhill area and the pre-descent buffer zone is similar to that for uphill driving and will not be elaborated here. When a vehicle enters area B from area A, the pre-descent energy management strategy is triggered; when the vehicle enters area C from area B, the in-descent energy management strategy is triggered; when the vehicle leaves area C, the in-descent energy management strategy is exited, and a semi-following energy management strategy is entered. The SOC trend of the power battery is as follows... Figure 4 As shown. When the vehicle's route is not fixed, when the vehicle's mileage reaches S=L d0 -L df When the vehicle's mileage reaches S=L, the VCU switches to the aforementioned pre-downhill energy management strategy; d0 When the VCU switches to the aforementioned energy management strategy during the downhill process, and S≥L d0 +L d When the VCU determines that the average slope of the downhill ahead is less than 1%, it exits the energy management strategy during the downhill process and automatically switches to the semi-following energy management strategy.

[0089] 1) Energy management strategies before going downhill.

[0090] Within the pre-downhill buffer zone, the power battery sets the target SOC to a lower value before descending the slope, namely the second set value SOC2 mentioned above. Using a second set time period as a cycle, the target power of the fuel cell is determined based on the current SOC of the power battery, the second set value, and the vehicle's average power in the previous cycle. This consumes power battery charge, freeing up battery capacity in advance for recovering downhill braking energy. The calculation formula for determining the target power of the fuel cell within the pre-downhill buffer zone is as follows:

[0091]

[0092] Among them, P fv_pre__Dtarget P represents the target power of the fuel cell within the buffer zone before the downhill slope. fc This is the vehicle's average power output over the previous cycle. The second time setting can be configured as needed, for example, within a range of 1-5 minutes.

[0093] 2) Energy management strategies during downhill driving.

[0094] During downhill driving, when the current SOC of the power battery is less than or equal to a third preset value, the target power of the fuel cell is the idle power; when the current SOC of the power battery is greater than the third preset value, the fuel cell shuts down. In this embodiment, the third preset value is 0.3. When SOC ≤ 0.3, the target power of the fuel cell is the idle power P. fc_Idle When SOC > 0.3, the fuel cell shuts down.

[0095] P fv_on__Dtarget =P fc_Idle (When SOC≤0.3)

[0096] P fv_on__Dtarget =0, (when SOC > 0.3)

[0097] Uphill Energy Management Device Example

[0098] The present invention provides an uphill energy management device for a fuel cell vehicle, such as... Figure 5 As shown, the device includes a processor that executes computer program instructions to implement the steps of the uphill energy management method for fuel cell vehicles described in the above-described embodiments of the uphill energy management method, which will not be described in detail here. The uphill energy management device also includes a memory and an internal bus. The processor and memory communicate and exchange data with each other via a CAN bus. The aforementioned memory and processor can be the memory and processor of the vehicle control unit (VCU). The processor can also be other processing devices in the vehicle, such as a microprocessor (MCU) or a programmable logic device (FPGA). The memory can also be other storage devices in the vehicle, such as high-speed random access memory (RAM), or non-volatile memory.

[0099] Downhill Energy Management Device Example

[0100] This invention discloses a downhill energy management device for a fuel cell vehicle, comprising a processor for executing computer program instructions to implement the steps of the downhill energy management method for fuel cell vehicles described in the above-described embodiments, which will not be described in detail here. The downhill energy management device also includes a memory and an internal bus, with the processor and memory communicating and exchanging data via a CAN bus. The aforementioned memory and processor can be the memory and processor of a vehicle control unit (VCU). The processor can also be other processing devices in the vehicle, such as a microprocessor (MCU) or a programmable logic device (FPGA). The memory can also be other storage devices in the vehicle, such as high-speed random access memory (RAM), or non-volatile memory.

[0101] The predictive fuel cell energy management strategy of this invention can pre-adjust the fuel cell energy distribution rules based on vehicle speed, throttle, and future road changes or specific areas. This solves the problems of poor power performance of fuel cell heavy-duty trucks under heavy loads on uphill sections in mountainous areas and lack of electric braking on downhill sections under heavy loads, while also improving the overall vehicle economy. For fixed operating routes and specific areas, an energy management strategy based on electronic fences is developed to improve the vehicle's power and economy. A rapid unloading strategy is developed based on braking status and battery charging capacity to improve electric braking performance, prevent air brake failure, increase the proportion of electric braking regenerative braking, and reduce the vehicle's hydrogen consumption.

Claims

1. A method of managing energy on an uphill slope for a fuel cell vehicle, characterized by, include: When the vehicle is operating from a flat road section to a long uphill section, the current state of power battery depletion is determined with the goal of the power battery reaching a first set value at the starting point of the long uphill. Based on the state of power battery depletion, the shortest length on the flat road section required to recharge the power battery before going uphill is determined. The area covering the shortest length in the flat road section before entering the long uphill section is recorded as the buffer zone before going uphill. Within the buffer zone before the uphill climb, the target power of the fuel cell within the buffer zone is determined based on the vehicle's current SOC and the calibrated relationship between the SOC of the power battery and the target power of the fuel cell. During the uphill process, if the throttle opening is not at its maximum, the target power of the fuel cell during the uphill process is determined based on the average power of the vehicle, the length of the slope, the climbing speed, the current SOC of the power battery, and the lower limit of the allowable SOC of the power battery, using the first set time as the cycle. The operation of the fuel cell is controlled according to the determined target power of the fuel cell.

2. The uphill energy management method for a fuel cell vehicle according to claim 1, characterized by, The calibration process is as follows: the SOC of the power battery is divided into N segments based on the balanced SOC of the power battery, and a calibration experiment is performed on each segment to determine the target power of the fuel cell corresponding to each segment. The SOC corresponding to the first segment is less than the balanced SOC of the power battery, and the SOC corresponding to the remaining segments increases sequentially based on the balanced SOC of the power battery until the upper limit of the power battery charging is reached; N≥3.

3. The uphill energy management method for fuel cell vehicles according to claim 1, characterized in that, During the uphill process, the target power of the fuel cell is the target power optimized based on the correction coefficient. The correction coefficient is calibrated according to the rate of change of the SOC of the power battery within the first set period. When the rate of change of the SOC of the power battery is large, the correction coefficient is greater than 1; when the rate of change of the SOC of the power battery is small, the correction coefficient is less than 1.

4. The uphill energy management method for fuel cell vehicles according to claim 1 or 3, characterized in that, During the uphill process, when the throttle opening reaches its maximum, the fuel cell target power is applied to the rated power at the fastest load change rate.

5. The uphill energy management method for fuel cell vehicles according to claim 1, characterized in that, The shortest length on a straight road section required to recharge the power battery before going uphill is calculated using the following formula: Wherein, L uf is the shortest length for the power battery to charge, SOC1 is the first set value, SOC current is the current SOC of the power battery, E b is the rated capacity of the power battery, u f is the common vehicle speed on flat road, P efc is the rated power of the fuel cell, P fv is the average power of the vehicle on flat road.

6. The uphill energy management method for fuel cell vehicles according to claim 1, characterized in that, The long uphill section refers to a section of road where the length of a continuous uphill slope is greater than a first threshold. The formula for calculating the first threshold is: Wherein, L u is the first threshold value, SOC b is the power battery balance SOC, SOC a is the power battery discharge lower limit, E b is the power battery rated capacity, u i is the climbing speed, P iv is the average power of the whole vehicle climbing, P efc is the rated power of the fuel cell.

7. The uphill energy management method for fuel cell vehicles according to claim 1, characterized in that, When vehicles are running on a fixed route, electronic fences are used to monitor whether vehicles enter the buffer zone before an uphill section or the uphill section.

8. A downhill energy management method for a fuel cell vehicle, characterized in that, include: When the vehicle is operating from a straight road section to a long downhill section, the power battery’s current power consumption is determined with the goal of the power battery’s SOC reaching a second set value at the starting point of the long downhill. Based on the power consumption, the shortest length on the straight road section required for the power battery to consume power before the downhill is determined. The area on the straight road section that covers the shortest length before entering the long downhill section is recorded as the buffer area before the downhill. Within the buffer zone before the downhill slope, the target power of the fuel cell is determined based on the current SOC of the power battery, the second set value, and the average power of the vehicle in the previous cycle, using the second set time as the cycle. During downhill driving, when the current SOC of the power battery is less than or equal to the third set value, the target power of the fuel cell is the idle power; when the current SOC of the power battery is greater than the third set value, the fuel cell shuts down. The operation of the fuel cell is controlled according to the determined target power of the fuel cell.

9. The downhill energy management method for fuel cell vehicles according to claim 8, characterized in that, The formula for calculating the target power of the fuel cell within the buffer zone before the downhill slope is as follows: Wherein, P fv_pre__Dtarget is the target power of fuel cell in the downhill front buffer area, SOC current is the current SOC of power battery, SOC2 is the second set value, P fc is the average power of vehicle in the previous period.

10. The downhill energy management method for a fuel cell vehicle according to claim 8 or 9, characterized in that, The long downhill section refers to a section where the elevation difference during continuous downhill descent exceeds the second threshold. The formula for calculating the second threshold is as follows: Wherein, SOC c is the upper limit of the power battery charging, SOC b is the balance SOC of the power battery, E b is the rated capacity of the power battery, m v is the total mass of the vehicle and the cargo, g is the acceleration of gravity, η e is the coefficient of the conversion of gravitational potential energy into electrical energy.

11. A hill-climbing energy management device for a fuel cell vehicle, comprising a processor, characterized in that, The processor is used to execute computer program instructions to implement the steps in the uphill energy management method for fuel cell vehicles as described in any one of claims 1-7.

12. A downhill energy management device for a fuel cell vehicle, comprising a processor, characterized in that, The processor is used to execute computer program instructions to implement the steps in the downhill energy management method for fuel cell vehicles as described in any one of claims 8-10.

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