Method for controlling power assembly

Abstract

To provide a method for controlling a power assembly with one or more fuel cell units and an electric energy storage system, the power assembly, a control unit, a vehicle, a computer program and a computer-readable medium.SOLUTION: A method predicts power demand to power supply from a power assembly over a predicted time horizon S1, acquires a state of charge (SoC) and / or power capacity of an electric energy storage system S2, specifies a period which is predicted that power can be supplied according to the predicted power demand or at least predicted that power can be supplied at the minimum power level determined regarding the predicted power demand in a state in which the power assembly stops fuel cell units on the basis of the predicted power demand, the acquired SoC and / or power capacity S3, and stops the fuel cell units at least for a part of the specified period in response to a fact that the specified period is larger than a time threshold S4.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a method for controlling a power assembly comprising one or more fuel cell units and an electrical energy storage system. The present invention further relates to a power assembly, a control unit, a vehicle, a computer program, and a computer-readable medium.

[0002] Although the present invention is described in relation to trucks, it is not limited to this particular vehicle and may be used in other vehicles such as passenger cars and off-road vehicles. The present invention may also be applied to ships and stationary applications such as grid-connected auxiliary generators and grid-off-grid generators. [Background technology]

[0003] Fuel cell systems can be used as an alternative or complement to batteries to power electric vehicles, but they can also be used in stationary applications such as grid-connected and grid-offside generators.

[0004] When a fuel cell system operates at a low current density, the polarization cell voltage of the fuel cell increases, negatively impacting the fuel cell's durability. To prevent fuel cell degradation, a maximum operating polarization cell voltage is set. This effectively means that the minimum operating power of the fuel cell is limited. Therefore, in certain situations, such as when a vehicle powered by a fuel cell system is traveling downhill, the fuel cell system may operate at a higher power than necessary to account for the vehicle's power demands. In this case, the excess power generated by the fuel cell system is stored in the battery. However, once the battery reaches its maximum charge state (SoC), the power generated by the fuel cell system may be dissipated and wasted.

[0005] To avoid energy dissipation, control strategies exist that turn off the fuel cell system when the battery's SoC is relatively high and power demand is low. U.S. Patent Application Publication 2016 / 0046204 discloses such a method for controlling a vehicle's fuel cell system, where the fuel cell is controlled to turn on or off depending on the vehicle's predicted power needs and the battery's SoC. However, turning the fuel cell on and off leads to fuel cell degradation and a shortened service life. [Overview of the project]

[0006] The main object of the present invention is to provide a method for controlling a power assembly comprising a fuel cell unit and an electrical energy storage system that is improved in at least one respect. In particular, the object is to provide a method that takes into account the degradation of the fuel cell unit that occurs in connection with the starting and stopping of the fuel cell unit.

[0007] According to a first aspect of the present invention, at least the main objective is achieved by the method described in claim 1.

[0008] Therefore, a method for controlling a power assembly is provided. The power assembly comprises a fuel cell unit and an electrical energy storage system for storing surplus electrical energy generated by the fuel cell unit. This method may be performed by a control unit of the power assembly. This involves forecasting power demand for power supplied from power assemblies over a predicted time horizon (prediction period), and To obtain at least one of the following: the charge state (SoC) and power capacity of the electrical energy storage system, Identifying a period within the forecast time horizon, based on the forecasted power demand and the acquired SoC and / or power capacity, during which the power assembly is expected to be able to supply power according to the forecasted power demand with the fuel cell unit shut down, or at least expected to be able to supply power at the minimum power level determined for the forecasted power demand. This includes controlling the power assembly to shut down the fuel cell unit for at least a portion of the specified period in response to the specified period being greater than a time threshold.

[0009] Therefore, according to the present invention, the power assembly may operate with the fuel cell turned off for a certain period of time. By setting a time threshold and comparing the specified period with the time threshold, if such an operating mode is undesirable, for example, due to fuel cell degradation resulting from stopping and starting the fuel cell, it becomes possible to refrain from turning off the fuel cell unit for a shorter period of time. Instead, the fuel cell unit can be shut down only if the benefits, such as reduced fuel consumption and improved energy efficiency, outweigh the drawbacks, such as rapid aging of the fuel cell unit.

[0010] During this period, the power assembly is expected to be able to supply power according to power demand or at least at a minimum power level, where the minimum power level is set in relation to the predicted power demand. Generally, the power assembly is capable of supplying power according to power demand for most of the period, e.g., 80% or more of the period, 90% or more of the period, or preferably over the entire period. Thus, shorter time intervals with lower power can be accepted, as long as the lower power does not fall below the specified minimum power. The minimum power level may be set according to performance requirements. For example, in a vehicle application, the minimum power level may be set so that the vehicle can travel at least a given vehicle speed.

[0011] The power assembly is intended to operate with the fuel cells turned off for at least a portion of a specified period, such as for the entire specified period or for a portion of the specified period starting from a specified appropriate point in time to turn off the fuel cell units, by controlling the power assembly to shut down the fuel cell units for at least a portion of the specified period. Thus, for at least a portion of the period, the power assembly operates in a purely electric mode, i.e., using only power from the electric energy storage system, or in a hybrid mode, using only power from the electric energy storage system and power from another fuel cell in the power assembly. The power assembly may comprise two or more fuel cell units, in which case the fuel cell units may be controlled independently or as a single system.

[0012] The above-mentioned period can be understood as the period during which the power assembly can be operated with the fuel cell unit turned off without violating the power limits defined by the predicted power demand and / or minimum power levels, and without violating the SoC limits of the electrical energy storage system (hereinafter sometimes referred to as ESS). SoC is an indicator of the amount of energy available in the ESS at a given point in time, and is usually expressed as a percentage of the energy capacity of a fully charged electrical energy storage system.

[0013] As used herein, the term “power capacity” refers to the charging and discharging capacity of an ESS. For example, as used herein, the term “power capacity” generally refers to the charging and discharging capacity of a battery within an ESS. The charging and discharging capacity of a battery generally refers to the state of the battery under normal use, such as in a vehicle. For example, State-of-Power (SoP) is an example of an operating parameter that indicates the power capacity of an ESS. The SoP of an ESS is defined by the maximum magnitude of constant current or power that can continuously charge or discharge the ESS during the next time horizon of interest, i.e., the predicted time horizon, without violating battery cell-level operating constraints. The SoP of an ESS may be determined with respect to either or both the magnitude of the current and / or the magnitude of the power.

[0014] When the fuel cell unit is off, energy is consumed from the ESS, so the ESS's State of Cubic (SoC) decreases over time. The change in SoC value over time is a function of the initial SoC and power demand. Therefore, the SoC value as a function of time over a predicted time horizon may be calculated from the predicted power demand and the ESS's initial SoC, which may be estimated from the ESS's measured open-circuit voltage (OCV), and / or determined using Coulomb counting, for example. Thus, obtaining the ESS's SoC may involve calculating the SoC as a function of time based on the initially obtained SoC and the predicted power demand. The initial SoC value may be received from the ESS's control system, such as a battery management unit or similar, or calculated based on measurement data received from the ESS.

[0015] The actual power or current that an ESS can supply varies depending on the ESS's SoC. As the SoC increases, so does the power capacity; therefore, a fully charged ESS can supply higher output power than an ESS with a relatively lower SoC. Thus, if the maximum output power of the ESS as a function of the SoC is known, the acquired SoC can be used to determine the maximum output power and compare it to the predicted power demand to determine whether the power assembly is expected to be able to supply power according to the predicted power demand with the fuel cell unit shut down.

[0016] If the specified period is shorter than the time threshold, the fuel cell unit remains on.

[0017] Optionally, the specified period is the period during which the power assembly is expected to be able to supply power according to the predicted power demand, or at the minimum power level, without violating the minimum SoC limit of the electrical energy storage system. The minimum SoC limit may be a predetermined limit. Since the minimum SoC limit may change with the aging of the ESS, the minimum SoC limit is set lower at the beginning of the ESS's life than it would be at an older ESS.

[0018] Optionally, specifying a period involves comparing the projected electricity demand with at least one electricity demand threshold.

[0019] Optionally, specifying a period further includes comparing the acquired SoC to at least one SoC threshold and / or comparing the power capacity to at least one power capacity threshold. Thus, specifying a period may include determining the maximum possible output power or current from the ESS and comparing the maximum possible output power or current to at least one power threshold.

[0020] Optionally, specifying a period includes identifying a first time point at which a predetermined first criterion is met and a second time point at which a predetermined second criterion is met, where the first time point and the second time point are respective endpoints of the period. Here, the first criterion is a criterion regarding the possibility of stopping the fuel cell unit, and the second criterion is a criterion regarding starting the fuel cell unit. The second time point follows the first time point.

[0021] Optionally, when the predicted power demand is below a first power demand threshold, and optionally when the SoC is above a first SoC threshold, and / or when the power capacity of the electrical energy storage system is above the first power demand threshold, the predetermined first criterion is considered to be met. Thus, when the predicted power demand is below the first power demand threshold, and optionally when the SoC / power capacity is above the first SoC / power capacity threshold, a possible first time point of the period is identified. Here, the SoC may be the SoC at the possible first time point, i.e., based on the initial SoC and the predicted power demand, the calculated SoC value is used. The first SoC threshold may be set to depend on the first power demand threshold. Instead of comparing the SoC with the first SoC threshold, the SoC may be used to determine the power capacity of the ESS, and that power capacity is compared with the first power capacity threshold. Alternatively, the power capacity may be obtained in other ways without using the SoC.

[0022] Optionally, when the predicted power demand exceeds a second power demand threshold, and optionally when the SoC is below a second SoC threshold, and / or when the power capacity is below a second power capacity threshold, a predetermined second criterion is considered to be satisfied. Thus, when the predicted power demand exceeds the second power demand threshold, and optionally when the SoC / power capacity is below the second SoC / power capacity threshold, a second time point of the period is identified, and at the second time point, it is necessary to restart the fuel cell unit so as not to violate the SoC and / or power limit of the power assembly. The SoC may be the SoC calculated at the second time point of the period. The second SoC threshold may be set to depend on the second power demand threshold. Instead of comparing the SoC with the second SoC threshold, the SoC may be used to determine the power capacity of the ESS, and then this power capacity may be compared with the second power capacity threshold. Alternatively, the power capacity may be obtained in other ways without using the SoC.

[0023] Also, if the predicted power demand remains below the second power demand threshold throughout the remaining predicted time horizon after the first time point, and optionally if the SoC remains below the second SoC threshold, and / or if the power capacity remains below the second power capacity threshold, the predetermined second criterion may be considered to be satisfied. In this case, the second time point is unknown, and the identified period may be determined to be greater than the time threshold.

[0024] Optionally, predicting the power demand includes predicting the instantaneous power demand as a function of time over the predicted time horizon, and identifying the period includes comparing the predicted instantaneous power demand with at least one power demand threshold. In this case, the predicted instantaneous power demand must be lower than the power demand threshold to identify the possible first time point of the period. When the predicted instantaneous power demand exceeds the power demand threshold, the second time point of the period is identified. Of course, the SoC of the ESS may also be considered to determine whether the first and second time points of the period have been reached.

[0025] Optionally, forecasting power demand involves determining the average power demand over at least a portion of the forecast time horizon, and identifying the period involves comparing the determined average power demand to at least one power demand threshold. The average power demand may be used in addition to, or as a substitute for, instantaneous power demand. The power demand threshold against which the average power demand is compared may be different from, and is typically lower than, the power demand threshold against which instantaneous power demand is compared. Naturally, the ESS's SoC and / or power capacity may also be taken into consideration when determining whether the first and second points in the period have been reached.

[0026] Optionally, the time threshold is a predetermined fixed value. This predetermined fixed value may be set considering the degradation of the fuel cell due to the shutdown and startup of at least one fuel cell unit, the efficiency loss of the power assembly during the period, and the expected fuel savings during the period. It may also take into account, for example, the degradation of the ESS resulting from charging the ESS beyond the maximum SoC limit.

[0027] Optionally, the method further includes determining a time threshold based on at least one of the expected degradation of the fuel cell due to the shutdown and startup of the fuel cell unit, the expected efficiency loss of the power assembly during the period, and the expected fuel savings during the period. Furthermore, the time threshold may be set based on the expected degradation of the ESS resulting from, for example, the maximum SoC limit, high ESS temperature, or charging the ESS beyond high current throughput. Thus, the time threshold may vary over the lifespan of the power assembly.

[0028] Optionally, a power assembly includes two or more fuel cell units, and specifying a period includes specifying a period during which the power assembly is expected to be able to supply power according to power demand with at least one of the two fuel cell units shut down, and in response that the specified period is greater than a time threshold, the at least one fuel cell unit is scheduled to be shut down for at least a portion of the specified period. Thus, some or all of the fuel cell units may be shut down during the specified period. The fuel cell unit(s) may not need to be turned on again after the specified period. Furthermore, if something unexpected happens, the fuel cell unit(s) may be turned on again during the specified period.

[0029] Optionally, the time threshold is set to a value unique to each of two or more fuel cell units. This may be relevant if two or more fuel cell systems differ in type, configuration, size, and / or years of service. This is because the degradation of fuel cell units during startup, shutdown, and operation differs depending on these factors. The threshold time is set to a value beyond which the cost of shutting down the fuel cell is lower than the cost of keeping the fuel cell on.

[0030] Optionally, the power assembly is adapted to supply the electricity that contributes to the propulsion of the vehicle, and predicting power demand is possible. Receiving vehicle-related information comprising at least one of the following: traffic information for the expected route of the vehicle during the predicted time horizon, terrain information for the expected route, topographic information for the expected route during the predicted time horizon, weather information for the expected route during the predicted time horizon, and total vehicle weight information. This includes using the above-mentioned received vehicle-related information to forecast power demand across a predicted time horizon.

[0031] One or more of the above vehicle-related information can contribute to accurate forecasting of electricity demand.

[0032] According to a second aspect of the present invention, a control unit as described in claim 13 is provided. Thus, a control unit configured to perform the method according to the first aspect is provided. The control unit may be an electronic control unit.

[0033] The advantages and effects of the second aspect of the present invention are substantially the same as those of the first aspect of the present invention.

[0034] According to a third aspect of the present invention, a power assembly as described in claim 14 is provided. The power assembly comprises one or more fuel cell units and an electrical energy storage system for storing surplus electrical energy generated by the one or more fuel cell units. The power assembly further comprises a control unit according to a second aspect.

[0035] According to a fourth aspect of the present invention, a vehicle as described in claim 15 is provided. The vehicle comprises a power assembly according to a third aspect, the power assembly being adapted to supply power that contributes to the propulsion of the vehicle. The power assembly may be configured to supply power in accordance with power requests received from the vehicle's control unit.

[0036] According to the fifth aspect, a computer program is provided which, when the program is executed on a computer, includes program code means for performing the method of the first aspect.

[0037] According to the sixth aspect, a computer-readable medium is provided that carries a computer program, wherein the computer program includes program code means for performing the method of the first aspect when the program is executed on a computer.

[0038] Further advantages and favorable features of the present invention are disclosed in the following description and dependent claims.

[0039] The embodiments of the present invention, as given as examples, will be described in more detail below with reference to the attached drawings. [Brief explanation of the drawing]

[0040] [Figure 1] This is a schematic side view of a vehicle. [Figure 2] This is a schematic diagram of a power assembly according to an exemplary embodiment of the present invention. [Figure 3] This shows an embodiment of the method of the present invention. [Figure 4a] This figure shows the predicted power demand as a function of time over the predicted time horizon. [Figure 4b] This figure shows the predicted power demand as a function of time over the predicted time horizon. [Figure 5a] This is a schematic block diagram showing a control unit according to an embodiment of this specification. [Figure 5b] This is a schematic block diagram showing a control unit according to an embodiment of this specification. [Modes for carrying out the invention]

[0041] The embodiments of the present invention, as given as examples, will be described in more detail below with reference to the attached drawings.

[0042] Figure 1 shows a side view of a vehicle 100 according to an exemplary embodiment of the present invention. Vehicle 100 is, in this case, a truck, more specifically, a heavy-duty truck for towing one or more trailers (not shown). Although a heavy-duty truck 100 is shown, it should be noted that the present invention is not limited to this type of vehicle and may be used in any other type of vehicle, such as buses, construction machinery, such as wheel loaders and excavators, and passenger cars. The present invention is also applicable to other non-vehicle-related applications as long as a power assembly including a fuel cell unit and an electrical energy storage system (ESS) is utilized.

[0043] The vehicle 100 comprises a power assembly 1 according to an exemplary embodiment of the present invention, where the power assembly 1 is used to power one or more electric motors (not shown) used to generate propulsion in the vehicle 100. The power assembly 1 may additionally or alternatively be used to power other power-consuming parts of the vehicle, such as an electric motor for a refrigerator system, an electric motor for an air conditioning system, or any other power-consuming function of the vehicle 100.

[0044] Vehicle 100 further comprises a control unit 5 according to an exemplary embodiment of the present invention. The control unit 5 is used to control the power assembly 1. While an onboard control unit 5 is shown, it should be understood that the control unit 5 may be a remote control unit 5, i.e., an offboard control unit, or a combination of onboard and offboard control units. The control unit 5 may be configured to control the power assembly 1 by issuing control signals and receiving status information relating to the power assembly 1. The control unit 5 may form part of the power assembly 1.

[0045] The control unit 5 is an electronic control unit and may include processing circuits adapted to execute a computer program disclosed herein. The control unit 5 may include hardware and / or software for performing the method according to the present invention. In some embodiments, the control unit 5 may be represented by a computer. The control unit 5 may consist of one or more separate sub-control units. Furthermore, the control unit 5 may communicate using wired and / or wireless communication means.

[0046] Figure 2 shows a schematic diagram of a power assembly 1 according to an exemplary embodiment of the present invention. The power assembly 1 may be used, for example, in a vehicle 100 as shown in Figure 1.

[0047] The power assembly 1 comprises at least one fuel cell unit, here a first fuel cell unit 2 and a second fuel cell unit 3. Each fuel cell unit 2, 3 may comprise one or more fuel cells, typically several fuel cells, although this is not shown in detail. Fuel cells are sometimes called fuel cell stacks, and a fuel cell stack may contain hundreds of fuel cells. Furthermore, each fuel cell unit is configured to provide the hydrogen fuel and air supply, cooling, etc., necessary for the fuel cell. Each fuel cell unit 2, 3 may have its own control system, which can be communicatively connected to the control unit 5. In the illustrated embodiment, the power assembly 1 comprises two fuel cell units 2, 3, but instead, it may comprise a single fuel cell unit, or more than two fuel cell units, such as three or more. Also, if several fuel cell units are provided, each fuel cell unit may be independently controllable or commonly controllable. If independently controllable, each fuel cell unit may be controlled to be on or off, regardless of the state(s) of the other fuel cell units(s). When two or more fuel cell units are to be controlled in common, the on or off state of those fuel cell units can be controlled in common, that is, all fuel cell units are controlled to the same state in common. The two fuel cell units may be controlled dependently on each other, such that one fuel cell unit is controlled to be on or off depending on the state of the other fuel cell unit.

[0048] The power assembly 1 further comprises an ESS 4, which may include one or more batteries for storing surplus electrical energy generated by the fuel cell units 2, 3 and for supplying output power from the power assembly 1. The ESS 4 is electrically connected to the fuel cell units 2, 3. The ESS 4 may have its own control system that is communicatively connected to the control unit 5. The ESS 4 may further be used to store energy regenerated during braking and / or may be configured to be charged by a charger, such as from an external power grid.

[0049] The power assembly 1 may further include power electronics (not shown) for converting the power generated by the fuel cell units 2 and 3, and / or power supplied from the ESS 4, into power usable by power consumption units 6, such as an electric motor or other power consumption unit. In addition to or instead of the above, the power assembly 1 may also include various components such as a compressor, sensors, pumps, valves, and electrical components.

[0050] Figure 3 illustrates a method for controlling a power assembly, such as power assembly 1 shown in Figure 2, according to an embodiment of the present invention. Referring to Figures 4a and 4b, two different exemplary operating scenarios are shown.

[0051] In the first step S1, the power demand P for the power supply from power assembly 1 over the predicted time horizon Δt is predicted. If power assembly 1 is fitted to supply power that contributes to the propulsion of vehicle 100, step S1 predicting the power demand P is: Receiving vehicle-related information comprising at least one of the following: traffic information for the expected route of vehicle 100 during the predicted time horizon Δt, terrain information for the expected route, topographic information for the expected route during the predicted time horizon Δt, weather information for the expected route during the predicted time horizon Δt, and total vehicle weight information. This includes using the received vehicle-related information described above to predict the power demand P over a predicted time horizon Δt.

[0052] A first step S1 of forecasting power demand P may include forecasting instantaneous power demand P(t) as a function of time t over a forecast time horizon Δt. Alternatively or additionally, the average power demand P over at least a portion of the forecast time horizon Δt may be forecasted. avg This may include determining that.

[0053] In the second step S2, the charge state (SoC) and / or power capacity of the electrical energy storage system 4 are obtained. Initial SoC or power capacity values, such as the SoC or power capacity of ESS4 when predicting the power demand P, may be received from the control system of ESS4 or determined within the control unit 5 based on measurement data from ESS4. The SoC and / or power capacity of ESS4 as a function of time t over the predicted time horizon Δt may be calculated in the control unit 5 as a function of the predicted power demand and the state of the fuel cell units 2, 3.

[0054] In the third step S3, based on the predicted power demand P and the acquired SoC and / or power capacity, a period δt within the predicted time horizon Δt is predicted, and during that period δt, it is expected that the power assembly 1 can supply power according to the predicted power demand P with the fuel cell units 2 and 3 shut down, or at least that the power assembly 1 can supply power at the minimum power level determined with respect to the predicted power demand P. The specified period δt is, for example, when the power assembly 1 is shut down, the minimum SoC limit SoC of the ESS4 min This may be a period during which power can be supplied in accordance with the predicted power demand P without violating the provisions, or during a period during which the power assembly (1) is expected to be able to supply power at the minimum power level.

[0055] A third step S3 for identifying period δt may include identifying a first time point t1 at which a predetermined first criterion is met, and a subsequent second time point t2 at which a predetermined second criterion is met. The first and second time points t1 and t2 are endpoints of period δt, respectively, where the first time point t1 may define a time at which the shutdown of fuel cell units 2 and 3 may be initiated, and the second time point t2 may define a time at which the startup of fuel cell units 2 and 3 must be initiated, or it is desirable that it be initiated. The predetermined first criterion is the time at which the predicted power demand P falls below a first power demand threshold, and optionally, when the SoC is below a first SoC threshold. th1The system may be configured to be considered satisfied when it exceeds a certain value, or when the power capacity of ESS4 exceeds the first power capacity threshold.

[0056] A predetermined second criterion may be set such that it is deemed satisfied when it is necessary to restart the fuel cell units 2 and 3. This is when the predicted power demand P exceeds the second power demand threshold, and optionally the SoC is the minimum SoC limit SoC of ESS4. min This can be satisfied if the second SoC threshold is not met, or if the power capacity of ESS4 is below the second power capacity threshold.

[0057] If instantaneous power demand is predicted in the first step S1, the period can be identified by comparing the predicted instantaneous power demand with at least one instantaneous power demand threshold. If average power demand is determined in the first step S1, the period can be identified by comparing the predicted instantaneous power demand with at least one average power demand threshold. A combination of instantaneous power demand thresholds and average power demand thresholds may be applied.

[0058] In the fourth step S4, in response that the specified period δt is greater than the time threshold dt, the power assembly 1 is controlled to shut down the fuel cell units 2 and 3 for at least a portion of the specified period δt. Thus, the specified period δt is compared to the time threshold dt. The time threshold dt may be a predetermined fixed value, or it may be determined based on at least one of the expected degradation of the fuel cells due to the shutdown and startup of the fuel cell units 2 and 3, the expected efficiency loss of the power assembly 1 during period δt, and the expected fuel savings during period δt. For example, if the expected fuel savings resulting from the shutdown of the fuel cell units are relatively large, a relatively short time threshold dt may be set, while if the expected fuel savings are small, a larger time threshold may be set. The time threshold can also be determined based on the expected ESS degradation. Step S4 may include initiating the shutdown of the fuel cell units 2 and 3 at a first time point t1, which is specified as the start point of period δt. Subsequently, power assembly 1 may be controlled to operate with fuel cell units 2 and 3 shut down for the entire specified period δt or longer, or to turn fuel cell units 2 and 3 back on at a later point in time, depending on the results of an updated forecast.

[0059] In some cases, the predicted power demand P may fall below the second power demand threshold, and the SoC and / or power capacity may be expected to remain above their respective second thresholds for the entire predicted time horizon Δt remaining after the first time point t1. In such cases, the time when the fuel cell units 2 and 3 need to be restarted will be after the predicted time horizon Δt. Therefore, it may be determined that the specified period δt is greater than the time threshold dt without actually specifying the second time point.

[0060] When the power assembly 1 includes two or more fuel cell units 2, 3, the third step S3 of specifying a period may include specifying a period δt during which the power assembly 1 can supply power according to the power demand P in a state where at least one of the at least two fuel cell units 2, 3 is stopped, i.e., turned off. In response to the specified period δt being greater than the time threshold dt, at least one of the two or more fuel cell units 2, 3 is stopped during the specified period δt. Thus, the power assembly 1 may be operated by turning off one of the fuel cell units 2, 3 and turning on the other during the period δt. Here, the time threshold dt may be set to a value specific to each of the two or more fuel cell units 2, 3. For example, when the behaviors and sizes of the fuel cell units 2, 3 are different, the deterioration occurring during stop and start is different. The time threshold dt may be set in consideration of such differences.

[0061] FIG. 4a schematically shows a first exemplary operation scenario of the power assembly 1. The upper diagram in FIG. 4a shows the power demand P as a function of time t of the power assembly 1, and the lower diagram shows the predicted SoC of the ESS 4 of the power assembly 1 as a function of time t. At time t0, the instantaneous power demand P(t) of the power assembly 1 shown by the solid line is first predicted over the prediction time horizon Δt. As shown by the dashed line, the average power demand P over the prediction time horizon Δt is also determined. avg is also determined.

[0062] In the first exemplary operation scenario, the average predicted power demand P avg and the instantaneous predicted power demand P(t) are below the first power demand threshold P th1 and the second power demand threshold P th2 respectively, and the SoC is at the first SoC threshold level SoC th1A first time point t1 that exceeds the given value is identified. This is considered to satisfy a predetermined first criterion, and the first time point t1 is identified as the time during which fuel cell units 2 and 3 can be shut down, and consequently, as the starting point of a period δt during which power assembly 1 can be operated with fuel cell units 2 and 3 turned off. The expected change in SoC after the possibility of shutting down fuel cell units 2 and 3 at the first time point t1 is shown as the dashed line SoC2, and the solid line SoC1 shows the change in SoC assuming that fuel cell units 2 and 3 remain on.

[0063] As can be seen from the diagram above, when fuel cell units 2 and 3 are turned off at the first time point t1, the SoC value is the minimum SoC limit SoC min It is expected to drop to the corresponding SoC threshold level, and at the second time point t2, fuel cell units 2 and 3 will need to be started. Therefore, at the second time point t2, the predicted average power P avg And instantaneous power P(t) are, respectively, from the second time point t2 onward, below the first power demand threshold P th1 and the second power demand threshold P th2 Even if it remains below the specified value, the second predetermined criterion is considered to be met. Therefore, the second time point t2 is identified as the endpoint of period δt.

[0064] Since the period δt is compared with the time threshold dt and it is found that the period δt is greater than the time threshold dt, the power assembly 1 may be controlled to shut down the fuel cell units 2 and 3 at the first time point t1. The startup of the fuel cell units 2 and 3 may be planned at the second time point t2, but the startup may be delayed or brought forward in response to unexpected events that were not considered in the initial forecast, for example. It is preferable that the forecast be continuously updated to identify such unexpected changes.

[0065] Figure 4b schematically illustrates a second exemplary operating scenario for power assembly 1. The same annotations as those used in the first exemplary operating scenario shown in Figure 4a are used, and the first time point t1 is identified as described above with reference to Figure 4a. However, in the second operating scenario, the predicted instantaneous power demand P(t) is set to the second power demand threshold P at the second time point t2. th2 It is increasing beyond that, and at the second time point t2, the SoC value is the minimum SoC limit SoC, as shown by the dashed line for SoC2. min This is just before the point in time when it is expected to fall below a certain threshold. Therefore, the second time point t2 is identified as the endpoint of the period δt for which the fuel cell units 2 and 3 are desired to be started. The period δt between the first time point t1 and the second time point t2 is compared to the time threshold dt. Since it is found that the period δt is less than the time threshold dt, in this case the power assembly 1 is controlled to keep the fuel cell units 2 and 3 in an operating state, i.e., on.

[0066] To perform the steps described herein, the control unit 5 may be configured to perform any one or more of the steps S1 to S4 described above, and / or any other example or embodiment described herein. The control unit 5 may include, for example, the configuration shown in Figures 5a and 5b.

[0067] The control unit 5 may include an input / output interface 500 configured to receive traffic information, terrain information, topography information, weather information, and gross vehicle weight information, for example, to receive system status from the ESS4, and to communicate with any necessary components and / or entities of the embodiments herein. The input / output interface 500 may include a wireless and / or wired receiver (not shown) and a wireless and / or wired transmitter (not shown). The control unit 5 may be located at any suitable location in the vehicle 100. The control unit 5 can use the input / output interface 500 to control and communicate with sensors, actuators, subsystems, and interfaces within the vehicle 100 by using any one or more of the Controller Area Network (CAN), Ethernet cable, Wi-Fi, Bluetooth®, and other network interfaces.

[0068] The control unit 5 is configured to predict the power demand for power supply from the power assembly 1 over a predicted time horizon, based on data received by the prediction unit 501 via the input / output interface 500.

[0069] The control unit 5 may also be configured to acquire at least one of the charge state (SoC) and power capacity of the electrical energy storage system 4 by the acquisition unit 502.

[0070] The control unit 5 is further configured to use a specific unit 503 to identify a period δt within the predicted time horizon Δt during which the power assembly 1 is expected to be able to supply power according to the predicted power demand while the fuel cell units 2 and 3 are shut down, or at least expected to be able to supply power at the minimum power level determined with respect to the predicted power demand. The specific unit 503 is configured to identify the period δt based on the predicted power demand and the acquired SoC and / or power capacity.

[0071] The control unit 5 is further configured to control the power assembly 1 to shut down the fuel cell units 2 and 3 during a specified period δt in response to the control unit 504 determining that the specified period δt is greater than a time threshold dt.

[0072] The methods described herein, along with computer program code for performing the functions and operations of the embodiments herein, may be implemented via a processor, such as the processor 560 of the processing circuit in the control unit 5 shown in Figure 5a, or via one or more processors. The program code described above may be provided as a computer program medium, for example, in the form of a data computer-readable medium that, when loaded into the control unit 5, carries the computer program code for performing the steps of the method herein. One such computer-readable medium may be in the form of a memory stick. Furthermore, the computer program code may be provided on a server as pure program code and downloaded into the control unit 5.

[0073] The control unit 5 may further include a memory 570 comprising one or more memory units. The memory 570 contains instructions that can be executed by the processor of the control unit 5. The memory 570 is configured to be used for storing, for example, information, data, control scenarios, costs, etc., in order to perform the method described herein when executed in the control unit 5.

[0074] In some embodiments, the computer program 580, when executed by a computer, for example, at least one processor 560, includes instructions that cause at least one processor of the control unit 5 to perform the method steps described above.

[0075] In some embodiments, the computer-readable storage medium 590 includes the respective computer program 580. The computer-readable storage medium 590 may also include program code for performing the method steps described above when the program product is executed on a computer, for example, on at least one processor 560.

[0076] Those skilled in the art will understand that the units within the control unit 5 described above may refer to one or more processors consisting of a combination of analog and digital circuits, and / or software and / or firmware stored in the control unit, each executed by one or more processors such as the processors described above. One or more of these processors and other digital hardware may be contained in a single application-specific integrated circuit (ASIC), or several processors and various digital hardware may be distributed across several separate components, whether individually packaged or assembled into a system-on-a-chip.

[0077] Naturally, the present invention is not limited to the embodiments described herein and shown in the drawings, and rather, those skilled in the art will recognize that many changes and modifications can be made within the scope of the appended claims.

Claims

1. A method for controlling a power assembly (1), The power assembly (1) comprises fuel cell units (2, 3) and an electrical energy storage system (4) for storing surplus electrical energy generated by the fuel cell units (2, 3). The aforementioned method, S1) predicts the power demand (P) for the power supply from the power assembly over a predicted time horizon (Δt), S2) obtains at least one of the charge state (SoC) and power capacity of the electrical energy storage system (4), S3) Identifying a period (δt) within the predicted time horizon (Δt) based on the predicted power demand (P) and the acquired SoC and / or power capacity, wherein during the period (δt), it is expected that the power assembly (1) can supply power according to the predicted power demand (P) with the fuel cell units (2, 3) shut down, or at least that the power assembly (1) can supply power at the minimum power level determined with respect to the predicted power demand. In response to the specified period (δt) being greater than the time threshold (dt), the power assembly (1) is controlled to shut down the fuel cell units (2, 3) for at least a portion of the specified period (δt) (S4), Methods that include...

2. The method according to claim 1, wherein the specified period is a period during which the power assembly (1) can supply power in accordance with the predicted power demand (P) or is expected to supply power at the minimum power level without violating the minimum SoC limit (SoCmin) of the electrical energy storage system (4).

3. Identifying the aforementioned period (δt) (S3) The predicted power demand (P) is compared with at least one power demand threshold (Pth1, Pth2), Optionally, compare the acquired SoC with at least one SoC threshold (SoCth1, SoCmin), and / or compare the power capacity with at least one power capacity threshold. The method according to claim 1, including the method described in claim 1.

4. Identifying the aforementioned period (δt) (S3) includes identifying a first time point (t1) in which a predetermined first criterion is met and a second time point (t2) in which a predetermined second criterion is met. The method according to claim 1, wherein the first time point and the second time point (t1, t2) are the respective endpoints of the period (δt).

5. The method according to claim 4, wherein the predetermined first criterion is deemed to be met if the predicted power demand (P) is below a first power demand threshold (Pth1), and optionally the SoC is above a first SoC threshold (SoCth1), and / or the power capacity is above a first power capacity threshold.

6. The method according to claim 4, wherein the predetermined second criterion is deemed to be met if the predicted power demand (P) exceeds a second power demand threshold (Pth2), and optionally if the SoC falls below a second SoC threshold, and / or if the power supply capacity falls below a second power supply capacity threshold.

7. Predicting the power demand (P) (S1) includes predicting the instantaneous power demand (P(t)) as a function of time (t) over the predicted time horizon (Δt), The method according to claim 1, wherein identifying the period (δt) (S3) includes comparing a predicted instantaneous power demand (P(t)) with at least one power demand threshold (Pth2).

8. Predicting the aforementioned power demand (P) (S1) includes determining the average power demand (Pavg) over at least a portion of the predicted time horizon (Δt), The method according to claim 1, wherein specifying the period (δt) (S3) includes comparing the determined average power demand (Pavg) with at least one power demand threshold (Pth1).

9. The method according to claim 1, wherein the time threshold (dt) is a predetermined fixed value, or the method further comprises determining the time threshold (dt) based on at least one of the expected degradation of the fuel cells due to the shutdown and startup of the fuel cell units (2, 3), the expected loss of efficiency of the power assembly (1) during the period (δt), and the expected fuel savings during the period (δt).

10. The power assembly (1) comprises two or more fuel cell units (2, 3), Identifying the aforementioned period (δt) includes identifying the period (δt) during which the power assembly (1) is expected to be able to supply power according to the power demand (P) with at least one of the at least two fuel cell units (2, 3) shut down. The method according to claim 1, wherein in response to the specified period (δt) being greater than the time threshold (dt), at least one fuel cell unit (2, 3) is scheduled to be shut down for at least a portion of the specified period (δt).

11. The method according to claim 10, wherein the time threshold (dt) is set to a value unique to each of the two or more fuel cell units (2, 3).

12. The power assembly (1) is adapted to supply power that contributes to the propulsion of the vehicle (100), Predicting the aforementioned electricity demand (P) is The system receives vehicle-related information comprising at least one of the following: traffic information for the expected route of the vehicle 100 during the predicted time horizon (Δt), terrain information for the expected route, topographic information for the expected route during the predicted time horizon (Δt), weather information for the expected route during the predicted time horizon (Δt), and total vehicle weight information. Using received vehicle-related information to predict the power demand (P) over the aforementioned predicted time horizon (Δt), The method according to claim 1, including the method described in claim 1.

13. A control unit (5) for controlling a power assembly (1), configured to perform the method described in any one of claims 1 to 12.

14. A power assembly (1) comprising one or more fuel cell units (2, 3) and an electrical energy storage system (4) for storing surplus electrical energy generated by the one or more fuel cell units (2, 3), further comprising the control unit (5) according to claim 13.

15. A vehicle (100) comprising a power assembly (1) according to claim 14, wherein the power assembly (1) is adapted to supply electricity that contributes to the propulsion of the vehicle (100).

16. Computer program (580), which, when executed on a computer, includes program code means for performing the method described in any one of claims 1 to 12.

17. A computer-readable medium (590) carrying a computer program (580), wherein the computer program (580), when executed on a computer, comprises program code means for executing the method described in any one of claims 1 to 12.

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