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EP-4737202-A1 - ROBUST ENERGY- OR RANGE-AWARE ADAPTIVE STATE-OF-CHARGE (SOC) WINDOW CONTROL

EP4737202A1EP 4737202 A1EP4737202 A1EP 4737202A1EP-4737202-A1

Abstract

A computer system (200) for adaptive state-of-charge (SoC) window control is provided, including processing circuitry (210) configured to: obtain a minimum required usable energy value (220) for an electric energy storage system (ESS, 240); obtain indications (230) of uncertainties for ESS usable energy estimation associated with at least one of i) aging of the ESS, ii) usage of the ESS, and iii) measurement errors of one or more parameters of the ESS; adapt, based on the indicated uncertainties, the minimum required usable energy value to a most likely minimum required usable energy value and/or a range of minimum required usable energy values for the ESS; define a SoC window for the ESS to match the most likely minimum required usable energy value and/or a value within the range of minimum required usable energy values, and control a discharging and/or charging (260) of the ESS in accordance with the SoC window.

Inventors

  • ALTAF, Faisal
  • LILLMAA, Henri

Assignees

  • Volvo Truck Corporation

Dates

Publication Date
20260506
Application Date
20241105

Claims (15)

  1. A computer system comprising processing circuitry configured to: - obtain a minimum required usable energy value ( E req ) for an electric energy storage system, ESS; - obtain one or more indications of one or more uncertainties for ESS usable energy estimation associated with at least one of i) aging of the ESS, ii) usage of the ESS, and iii) measurement errors of one or more parameters of the ESS; - adapt, based on the indicated one or more uncertainties, the minimum required usable energy value to a most likely minimum required usable energy ( E req ∗ ) value and/or a range of minimum required usable energy values ([ E reqLow , E reqHigh ]) for the ESS; - define a state-of-charge, SoC, window ([ SoC winLow , SoC winHigh ]) for the ESS to match the most likely minimum required usable energy value and/or a value within the range of minimum required usable energy values, and - control a discharging and/or charging of the ESS in accordance with the SoC window.
  2. The computer system of claim 1, wherein the one or more uncertainties for ESS usable energy estimation are associated with ohmic losses of the ESS due to impedance increasing with age and/or temperature of the ESS.
  3. The computer system of claim 1 or 2, wherein the one or more uncertainties for ESS usable energy estimation are associated with estimation errors of ESS state-of-charge, SoC, and/or state-of-health, SoH.
  4. The computer system of any one of claims 1 to 3, wherein the one or more uncertainties for ESS usable energy estimation are associated with unusable ESS capacity due to cell-to-cell and/or pack-to-pack balancing errors.
  5. The computer system of any one of the preceding claims, wherein the one or more uncertainties for ESS usable energy estimation are associated with ESS pack-to-pack state-of-charge, SoC, estimation synchronization errors.
  6. The computer system of any one of the preceding claims, wherein the ESS forms part of an electric vehicle, and wherein the processing circuitry is further configured to calculate the minimum required usable energy value based on a minimum range requirement for the vehicle.
  7. The computer system of any one of the preceding claims, wherein the processing circuitry is configured to define the range of minimum required usable energy values as a mean required usable energy value plus one or more confidence intervals for the required usable energy value.
  8. The computer system of any one of the preceding claims, wherein the processing circuitry is configured to define the SoC window based on an upper limit ( E reqHigh ) of the range of minimum required usable energy.
  9. The computer system of any one of claims 1 to 7, wherein the processing circuitry is configured to define the SoC window based on a mean value ( E reqMean ) of the range of minimum required usable energy.
  10. The computer system of any one of claims 1 to 7, wherein the processing circuitry is configured to define the SoC window based on a lower limit ( E reqLow ) of the range of minimum required usable energy.
  11. An energy storage system, ESS, comprising the computer system of any one of claims 1 to 10.
  12. An electric vehicle, comprising the computer system of any one of claims 1 to 10 and the energy storage system, ESS.
  13. A computer-implemented method, comprising: - obtaining, by processing circuitry of a computer system, a minimum required usable energy value for an electric energy storage system, ESS; - obtaining, by the processing circuitry, one or more indications of one or more uncertainties for ESS usable energy estimation associated with at least one of i) aging of the ESS, ii) usage of the ESS, and iii) measurement errors of one or more parameters of the ESS; - adapting, by the processing circuitry and based on the indicated one or more uncertainties, the minimum required usable energy value to a most likely minimum required usable energy value and/or a range of minimum required usable energy values ([ E reqLower , E reqUpper ]) for the ESS; - defining, by the processing circuitry, a state-of-charge, SoC, window ([ SoC winLow , SoC winHigh ]) for the ESS to match the most likely minimum required energy value and/or a value within the range of minimum required usable energy values, and - controlling, by the processing circuitry, a discharging and/or charging of the ESS in accordance with the SoC window.
  14. A computer program product comprising program code for performing, when executed by the processing circuitry, the method of claim 13.
  15. A non-transitory computer-readable storage medium comprising instructions, which when executed by the processing circuitry, cause the processing circuitry to perform the method of claim 13.

Description

TECHNICAL FIELD The disclosure relates generally to the field of battery energy storage systems. In particular aspects, the disclosure relates to a more robust energy- or range-aware adaptive state-of-charge (SoC) window control for such systems. The disclosure can be applied to energy storage systems such as used in heavy-duty vehicles, such as trucks, buses, and construction equipment, among other vehicle types. Although the disclosure may be described with respect to a particular vehicle, the disclosure is not restricted to any particular vehicle. The envisaged solution is applicable also to energy storage systems used outside of a vehicle. BACKGROUND A battery energy storage system (ESS, or BESS) usually includes one or more battery packs. The ESS is used to store energy in a safe, robust and preferably optimal way, and to deliver/receive power as part of a range of different applications under varying operation conditions. If used for example in an electric vehicle, the performance (in terms of e.g. usable energy and power ability) of the ESS may have a direct impact on the performance of the vehicle (in terms of e.g. chargeability, drivability, average speed, and range). A problem with contemporary ESS solutions is that their performance attributes degrade over time due to aging of the batteries, both as a result of usage but also due to calendar aging, which in turn leads to a reduced vehicle performance over time. To limit the wear on the batteries, fully discharging and/or charging the batteries is often avoided by defining a so-called state-of-charge (SoC) window, that establishes limits for when to stop discharging and/or charging the ESS. For a particular SoC window, there is a particular usable energy (expressed in terms of kilowatt hours, kWh, or joules) that is deliverable from/to the ESS while meeting requirements for durability, safety, drivability, charging speed, thermal management, and similar. The usable energy is a nonlinear function of battery characteristics such as capacity, impedance, open-circuit-voltage (OCV), the SoC window, temperature, and similar. As battery aging leads to capacity fading and impedance growth, the usable energy, and thus also the performance of the vehicle, also decreases over time as a function of the state-of-health (SoH) of the ESS, which may worsen the experience of a user of the vehicle. To meet usable energy requirements over the lifetime of the ESS, a battery management system (BMS) typically employes one of two solutions. A first such solution includes to use a fixed SoC window control strategy in which the SoC window limits are fixed according to assumed end-of-life (EoL) capacity and impedance characteristics of the ESS. Such a strategy is however no optimal from e.g. a mission-planning perspective, as the usable energy and hence vehicle range will (monotonically) decrease with time. Phrased differently, the user may have more than required range at beginning-of-life (BoL) of the ESS, and the range will then fade and finally reach the required value once the EoL of the ESS is reached. Such time-varying vehicle performance may worsen the user experience, and a fixed SoC window control strategy may also be less than optimal from a battery aging dynamics viewpoint as it may potentially lead to higher aging rate. The other solution includes to adaptively adjust the SoC window over time as a function of ESS aging dynamics, to always deliver a same required usable energy from BoL to EoL. Phrased differently, as the ESS ages, the SoC window is increased to maintain the corresponding usable energy at a constant level. Although perhaps better than the first, fixed SoC window solution, attempting to adaptively adjust the SoC window may be prone to errors introduced due to e.g. parametric uncertainties, measurement errors and e.g. state estimation errors, and similar. The present disclosure seeks to improve upon contemporary solutions for adaptively adjusting the SoC window over time. SUMMARY According to a first aspect of the disclosure, there is provided a computer system that includes processing circuitry. The processing circuitry is configured to obtain a minimum required usable energy value for an ESS. The processing circuitry is configured to obtain one or more indications of one or more uncertainties for ESS usable energy estimation associated with at least one of i) aging of the ESS, ii) usage of the ESS, and iii) measurement errors of one or more parameters of the ESS. The processing circuitry is further configured to adapt, based on the indicated one or more uncertainties, the minimum required usable energy value to a most likely minimum required usable energy value and/or a range of minimum required usable energy values for the ESS. The processing circuitry is configured to define a SoC window for the ESS to match the most likely minimum required usable energy value and/or a value within the range of minimum required usable energy values. The proces