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EP-4551422-B1 - A METHOD OF CONTROLLING AN ELECTRIC POWER SYSTEM OF A FUEL CELL ELECTRIC VEHICLE

EP4551422B1EP 4551422 B1EP4551422 B1EP 4551422B1EP-4551422-B1

Inventors

  • ANDERSSON, ARNE
  • AUDHAV, TOVE
  • BLOMGREN, FREDRIK
  • LUONG, Staffan
  • SKVOR, Eva

Dates

Publication Date
20260506
Application Date
20220704

Claims (15)

  1. A computer implemented method of controlling an electric power system (102) of a fuel cell electric vehicle, FCEV (10), the electric power system comprising a fuel cell (106) and an energy storage system (104) electrically connected to each other, wherein the FCEV comprises an electric traction motor (101) connected to the electric power system, the electric power system being configured to feed electric power to the electric traction motor at a propulsion power level range during propulsion, and to receive electric power, generated by the electric traction motor, during braking, the electric power system being operable to assume a low load operation mode, in which electric power is fed to an energy consumer (110, 110', 110") of the FCEV at a power level below the propulsion power level range, the energy consumer (110, 110', 110") being different from the electric traction motor (101), and processing circuitry operatively coupled to the energy storage system, the method comprising: - determining (S1), by the processing circuitry, an upcoming position (204) at which the electric power system will assume the low load operation mode; - determining (S2), by the processing circuitry, a current state of charge level of the energy storage system; - determining, by the processing circuitry, a desired state of charge level of the energy storage system when ending the low load operation mode; - determining, by the processing circuitry, an energy consumption level of the energy consumer during the low load operation mode; - determining, by the processing circuitry, a charging level of the energy storage system by the fuel cell during the low load operation mode; - determining (S3), by the processing circuitry, a power distribution scheme between the electric power system and the electric traction motor for arriving at the upcoming position with a state of charge level of the energy storage system below a predetermined threshold level, wherein the predetermined threshold level of the energy storage system when arriving at the upcoming position is based on the desired state of charge level and a difference between the charging level of the energy storage system and the energy consumption level of the energy consumer; - controlling (S4), by the processing circuitry, the electric power system based on the power distribution scheme; and - controlling (S5), by the processing circuitry, the electric power system to feed electric power from the fuel cell at least to the energy consumer when the electric power system assumes the low load operation mode at the upcoming position.
  2. The computer implemented method according to claim 1, further comprising: - determining, by the processing circuitry, an electric energy consumption of the electric traction motor for arriving at the upcoming position; wherein the power distribution scheme is based on the determined electric energy consumption.
  3. The computer implemented method according to claim 2, wherein the determined electric energy consumption is based on scheduled operational information of the electric traction motor for propelling the FCEV from a present position to the upcoming position.
  4. The computer implemented method according to any one of claims 2 or 3, further comprising: - determining, by the processing circuitry, a road topology for a road path (402) from a present position to the upcoming position to be operated by the FCEV; and wherein the determined electric energy consumption is based on the road topology from the present position to the upcoming position.
  5. The computer implemented method according to any one of claims 2 - 4, further comprising: - dividing, by the processing circuitry, an upcoming road path from a current position to the upcoming position into a plurality of road path sections (406), each road path section being associated with individual road topology data; wherein the electric energy consumption of the electric traction motor is determined for each road path section.
  6. The computer implemented method according to claim 5, further comprising: - setting, by the processing circuitry, a desired state of charge level of the energy storage system at the upcoming position, the desired state of charge level being below the predetermined threshold level; - determining, by the processing circuitry, a desired electric energy capacity of the electric power system for each road path sections to arrive at the upcoming position with the desired state of charge level of the energy storage system, the desired electric energy capacity for each road path section being based on its next coming road path section; and - controlling, by the processing circuitry, the electric power system based on the desired electric energy capacity of each road path section.
  7. The computer implemented method according to any one of the preceding claims, further comprising: - controlling, by the processing circuitry, the electric power system to feed electric power solely from the energy storage system to the electric traction motor during at least a portion of a travelling distance from a present position to the upcoming position when the current state of charge level of the energy storage system is above an upper threshold level.
  8. The computer implemented method according to any one of the preceding claims, wherein the fuel cell is operable to assume an idle mode in which the fuel cell generates electric power at a first power level, and a power mode in which the fuel cell generates electric power at a second power level, the second power level being higher than the first power level.
  9. The computer implemented method according to any one of the preceding claims, wherein the FCEV is arranged in a stand-still operating mode when the electric power system assumes the low load operation mode.
  10. The computer implemented method according to any one of the preceding claims, wherein the energy consumer consumes electric power at a power level below the power level generated by the fuel cell when the electric power system assumes the low load operation mode, wherein a difference between electric power generated by the fuel cell and the electric power consumed by the energy consumer is fed from the fuel cell to the energy storage system when the electric power system assumes the low load operation mode.
  11. A control unit (114) for controlling an auxiliary system of a transportation vehicle, the control unit being configured to perform the method according to any of claims 1- 10.
  12. An electric power system (102) of a fuel cell electric vehicle, FCEV (10), the electric power system comprising a fuel cell (106), an energy storage system (104) electrically connected to the fuel cell, and a control unit (114) according to claim 11; the control unit (114) being connected to the fuel cell, the electric power system being configured to feed electric power to an electric traction motor of the FCEV during propulsion at a propulsion power level range, and to assume a low load operation mode in which the electric power system feeds electric power to an energy consumer (110, 110', 110") of the FCEV at a power level below the propulsion power level range, the energy consumer (110, 110', 110") being different from the electric traction motor (101).
  13. A computer program comprising program code means for performing the method of any of claims 1 - 10 when the program is run on a control unit (114) according to claim 11.
  14. A non-transitory computer readable medium carrying a computer program comprising program code for performing the method of any of claims 1 - 10 when the program product is run on a control unit (114) according to claim 11.
  15. A fuel cell electric vehicle, FCEV (10) comprising an electric power system (102) according to claim 12.

Description

TECHNICAL FIELD The present invention relates to an electric power system comprising an energy storage system and a fuel cell. In particular, the invention relates to a method of controlling such electric power system. The invention is applicable on so-called fuel cell electric vehicles (FCEV), in particular medium- and heavy-duty FCEVs. Although the invention will be described with respect to a heavy-duty FCEV in the form of a truck, the disclosure is not restricted to this particular vehicle, but may also be used in other FCEVs. BACKGROUND Electrified propulsion of passenger cars is becoming a conventional solution to reduce the environmental effect caused by vehicles. Heavy-duty vehicles, such as trucks, are also continuously developed to be able to provide electrified propulsion. The electrified propulsion system comprises one or more electric machines operable to generate a propulsion torque on one or more wheels of the vehicle. However, heavy duty vehicles require a large energy capacity of the batteries feeding electric power to the electric machines in order to provide a desirable vehicle operational range. The electric capacity of the batteries is thus a limiting factor for the heavy-duty vehicles. Using a fuel cell to generate electric power during operation of the vehicle is one approach to increase the operational range for heavy-duty vehicles. The electric power generated by the fuel cell can be fed to the battery/batteries, or fed directly to the electric machine propelling the vehicle. To reduce degradation of the fuel cell, the fuel cell should preferably not be turned off during operation of the FCEV. However, during particular operating conditions, the energy storage system might not be able to receive the electric power generated by the fuel cell, due to e.g. the state of charge level of the energy storage system being above a certain limit. In such a case, the electric power generated by the fuel cell would have to be dissipated or the fuel cell turned off. Dissipating electric energy is not efficient and, as previously mentioned, there is a desire to not shut down the fuel cell. Thus, a solution where both these can be avoided is desired. According to its abstract, US 2014/277931 relates to power systems and methods that can provide power system management and power delivery, among other functionality. The power systems and methods for a vehicle can employ a fuel cell, such as a Solid Oxide Fuel Cell (SOFC), as a power source in conjunction with another power sources, such as one or more vehicle batteries, capacitors, etc. The fuel cell can be conditionally used to provide power to the electrical system, thereby reducing the load on the vehicle batteries. According to its abstract, US 2014/288737 relates to a method of controlling power of the fuel cell vehicle includes dividing an expected driving path of the fuel cell vehicle into a plurality of sections and setting the plurality of sections according to a gradient, and comparing whether a predicted battery state of charge variation is within a battery charging/discharging allowance range for each of the plurality of divided sections The method further includes comparing predicted power with a predetermined maximum allowance power for each of the plurality of divided sections, and setting the plurality of divided sections as a battery charging/discharging prohibition section and a battery charging/discharging allowance section in advance according to a result of the comparison of the predicted battery state of charge variation and the predicted power. Further, EP 3 173 304 describes in its abstract a method for determining and optionally in addition to implementing an optimal route for a vehicle or by the vehicle, wherein the vehicle comprises an electric drive with an energy storage and comprises a converter, wherein the converter is operated by means of a fuel, wherein the converter Energy storage of the electric drive is chargeable, comprising the steps Predetermining a target position Z by the user, Determining one or more possible routes from the current position A to the destination position Z, the determination depending on the geographical location of both fuel stations and fuel charging stations in the area between the current position A and the destination position Z, - determining the optimal route by selecting from the determined possible routes, Optionally, implementing the optimal route by purposefully operating the converter to charge the energy storage while traveling the optimal route. According to a further state of the art document, WO 2022/033308 relates to a FCEV energy management method and system. SUMMARY It is thus an object of the present disclosure to mitigate the above-described deficiencies. The invention is defined in the appended claims. Here below the term "example embodiment" relates to example embodiment of the disclosure. According to a first aspect, there is provided a computer implemented method of