SE2151127A1 - Control system and method for controlling charging of an energy storage device - Google Patents

Abstract

A control system (100) and a method for controlling charging on an energy storage device (4) of a vehicle (1) during a charging procedure are provided. The method comprises a step of, based on a predicted desired amount of charging energy by which the energy storage device (4) is to be charged curing the charging procedure and a predetermined allowable duration for the charging procedure, determining a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device so as to reduce the risk of aging of the energy storage device (4). Said charging profile defines charging current and temperature of the energy storage device (4) over time. The method further comprises a step of charging the energy storage device (4) while controlling charging current and the temperature of the energy storage device in accordance with the determined charging profile.

Description

CONTROL SYSTEM AND METHOD FOR CONTROLLING CHARGING OF AN ENERGY STORAGE DEVICE TECHNICAL FIELD The present disclosure relates in general to a method for controlling charging of an energy storage device of a vehicle during a charging procedure. The present disclosure further relates in general to a control system configured to control charging of an energy storage device of a vehicle during a charging procedure. Moreover, the present disclosure relates in general to a computer program as well as a computer-readable medium.

BACKGROUND The strive to reduce emissions and improve fuel economy of heavy vehicles, such as trucks and buses, has led to the development of vehicles comprising propulsion systems that uses one or more electrical machines. These electrical machines may be powered by energy storage devices, such as secondary lithium-ion batteries, that require charging at designated charging stations or zones. Examples of such vehicles include Hybrid Electric Vehicles (HEVs), Plug-in Hybrid Electric Vehicles (PHEVs), and Battery Electric Vehicles (BEVs).

Energy storage devices for vehicles, such as secondary lithium-ion energy storage devices, are built up from a number of electrochemical cells. These electrochemical cells can store or release energy through electrochemical reactions. Each electrochemical cell comprises an anode, a cathode and an electrolyte between the anode and the cathode. The electrolyte is an electrically insulating, but ionically conducting electrolyte enabling ions to move through the electrochemical cell. The electrochemical cell further comprises a separator arranged between the anode and cathode. The separator is configured to contain the electrolyte and to prevent short circuit between the anode and the cathode.

The service life of the energy storage devices, used for powering the electrical machine(s) of the vehicle, is an essential factor when considering the total life cost of the vehicle. Thus, there is a continuous strive to increase the service life of such energy storage devices. The service life of an energy storage device is dependent of the configuration of the energy storage device as such, for example by the selection of constituent materials of the energy storage device (such as the electrolyte or the electroactive materials). Thus, the service life of an energy storage device may be increased by modifying the configuration of the energy storage device. However, the service life is also affected by how the energy storage device is operated. ln other words, the service life of an energy storage device is affected by e.g. how it is charged and discharged. For example, a low charging rate may in general lead to a lower risk of aging of energy storage device. However, this in turn also leads to an increase of the duration of the charging procedure, which may lead to longer times the vehicle is out of service. Therefore, this is often not an appropriate strategy for heavy vehicles where the time during which the vehicle is out of service may be very costly for the owner of the vehicle.

SE 1550115 A1 discloses a method for charging an energy storage unit of a vehicle in a first charging zone, for reaching a subsequent charging zone. The method comprises determining current charging level of the energy storage unit, calculating required charging level for the vehicle being able to reach the subsequent charging zone, and estimating remaining time the vehicle will remain within the first charge zone. The method further comprises charging the energy storage unit of the vehicle at least up to the calculated required charging level, distributed over the estimated remining time the vehicle will remain within the first charging zone. Said method provides an efficient charging of the energy storage unit since it is not charged faster, or more, than required for reaching the subsequent charging zone in the route of the vehicle. This is a simple and straight-forward method that may increase the lifetime of the energy storage unit compared to, for example, always seeking to fully charge the energy storage unit at a charging zone under the constrain of the time the vehicle may remain within the charging zone. However, said method does not consider the aging of the energy storage device.

CA 3052382 proposes a method for charging a lithium-ion battery to reduce charging duration and battery degradation. The method comprise applying an input current at a first charge rate until a lithium-ion concentration in an electrolyte at an anode current collector decreases below 500 mol/m3. Thereafter, the method comprises applying an input current at a second charge rate, wherein this maintains a constant lithium-ion concentration in an electrolyte at the anode current collector. The second charge rate is less than the first charge rate. Thereafter, the method comprises applying an input current at a decreasing rate, wherein the decreasing rate reduces lithium plating on a surface of the anode.

SUMMARY The object of the present invention is to further improve the service life of an energy storage device of a vehicle.

The object is achieved by the subject-matter of the appended independent c|aim(s). ln accordance with the present disclosure, a method for controlling charging on an energy storage device of a vehicle during a charging procedure is provided. The method is performed by a control system. The method comprises a step of, based on a predicted desired amount of charging energy by which the energy storage device is to be charged curing the charging procedure and a predetermined allowable duration for the charging procedure, determining a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device so as to reduce the risk of aging of the energy storage device. Said charging profile defines charging current and temperature of the energy storage device over time. The method further comprises a step of charging the energy storage device while controlling charging current and the temperature of the energy storage device in accordance with the determined charging profile.

By means of the present method, the service life of the energy storage device may be extended. This is achieved by, under the constraints of allowable duration for the charging procedure and amount of charging energy by which the energy storage device is to be charged, controlling the charging current as well as the temperature of the energy storage device during the charging procedure such that the aging of the energy storage device is minimized. Furthermore, by charging the energy storage device to a state of charge appropriate for the route of the vehicle until the next charging procedure (defined by the predicted desired amount of charging energy by which the energy storage device is to be charged during the charging procedure), the allowable duration for the charging procedure may be more efficiently used in contrast to e.g. always fully charging the energy storage device. Fully charging is here intended to mean charging to a selected maximum state of charge allowed for the energy storage device.

As evident from the above, both the charging current and the temperature of the energy storage device is controlled in accordance with the present method. ln general, charging of an energy storage device may result in a change in temperature of the energy storage device which in turn affects the result of an applied charging current. However, since the present method not only controls the charging current but also the temperature of the energy storage device, it is possible to ensure that the energy storage device is appropriately charged while avoiding the risk of undue aging of the energy storage device.

By charging the energy storage device is accordance with the determined charging profile, a good balance between the time the vehicle may need to be out of operation due to a charging procedure and the service life of the energy storage device may be achieved. Extending the service life of the energy storage device of the vehicle also reduces the total cost for the service life of the vehicle since it reduces the number of times the energy storage device needs to be replaced due to aging. Thus, the present method improves the total economy for the owner of the vehicle.

The method may further comprise a step of predicting a desired amount of charging energy by which the energy storage device is to be charged during the charging procedure based on a current state of charge of the energy storage device, a predicted state of charge of the energy storage device required for the vehicle to travel from a first charging station or charging zone at which the charging procedure is to be performed to a second charging station or charging zone where a subsequent charging procedure may be performed, and optionally a pre-selected offset state of charge. Thereby, an appropriate and accurate charging profile may be determined. This in turn improves the control of the charging procedure and may therefore also extend the service life of the energy storage device.

The method may further comprise a step of predicting the state of charge of the energy storage device required for the vehicle to travel from the first charging station or charging zone to the second charging station or charging zone based on geographical data relating to a route of the vehicle from the first charging station or charging zone to the second charging station or charging zone. Thereby, a more accurate prediction of the state of charge of the energy storage device required for the vehicle until a subsequent charging procedure may be performed may be achieved. Thereby, an appropriate and accurate charging profile may be determined and hence an extended service life of the energy storage device.

The predetermined aging model may comprise a model for solid electrolyte interphase (SEI) formation in the energy storage device. Growth of SEI leads to loss of capacity and thus constitutes an important aging factor of an energy storage device. Thus, when the predetermined aging model comprises a model for SEI formation, the present method minimizes the risk of aging of the energy storage device due to SEI under the constraints of the allowable duration of the charging procedure and the amount of charging energy. Thereby, the service life of the energy storage device may be further extended.

The controlling of the temperature of the energy storage device in accordance with the determined charging profile may comprise controlling the temperature of a coolant of the energy storage device and/or controlling a heater configured to heat the energy storage device. Thereby, the temperature of the energy storage device may be controlled during the charging procedure so as to follow the determined charging profile by usage of already existing devices therefore.

The method may further comprise monitoring the charging procedure, and, in response to a detection of a deviation from the determined charging profiled for the charging procedure, determining a revised charging profile for the remaining portion of the charging procedure. Thereby, the control of the charging during the charging procedure may be further improved since it may take into account unexpected circumstances during the charging procedure and adapt the charging accordingly.

The energy storage device may suitably comprise a lithium-ion secondary energy storage device.

The present disclosure further provides a computer program comprising instructions which, when executed by a control system, cause the control system to carry out the method as described above.

Moreover, the present disclosure provides a computer-readable medium comprising instructions which, when executed by a control system, cause the control system to carry out the method as described above.

The present disclosure also relates to a control system configured to control charging of an energy storage device of a vehicle during a charging procedure. The control system is configured to, based on a predicted desired amount of charging energy by which the energy storage device is to be charged during the charging procedure and a predetermined allowable duration for the charging procedure, determine a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device so as to reduce the risk of aging of the energy storage device. Said charging profile defines charging current and temperature of the energy storage device over time. The control system is further configured to charge the energy storage device while controlling the charging current and the temperature of the energy storage device in accordance with the determined charging profile.

The control system has the same advantages as described above with regard to corresponding method for controlling charging of an energy storage device of a vehicle during a charging procedure described above.

The control system may further be configured to predict a desired amount of charging energy by which the energy storage device is to be charged during the charging procedure based on a current state of charge of the energy storage device, a predicted state of charge of the energy storage device required for the vehicle to travel from a first charging station or charging zone at which the charging procedure is to be performed to a second charging station or charging zone where a subsequent charging procedure may be performed, and optionally a pre-selected offset state of charge.

The control system may for example comprise a charging unit configured to provide a charging current to the energy storage device, a temperature control unit configured to control the temperature of a coolant of the energy storage device and/or a heater configured to heat the energy storage device, and a control device configured to control the charging current provided by the charging unit to the energy storage device and, by usage of the temperature control unit, the temperature of the energy storage device in accordance with the determined charging profile.

The present disclosure further provides a system comprising a vehicle comprising an energy storage device, at least one charging station or charging zone where the energy storage device may be charged, and the above-described control system configured to control charging of an energy storage device of a vehicle during a charging procedure.

BRIEF DESCRIPTION OF DRAWINGS Fig. 1 illustrates an example of a vehicle present at a charging station; Fig. 2 schematically illustrates an example of an electrochemical cell of an energy storage device; Fig. 3 represents a flowchart schematically illustrating one exemplifying embodiment of the herein described method for controlling charging of an energy storage device of a vehicle during a charging procedure; Fig. 4 schematically illustrates one exemplifying embodiment of a control system, configured to control charging of an energy storage device of a vehicle during a charging procedure, in accordance with the present disclosure; Fig. 5 schematically illustrates an exemplifying embodiment of a device which may comprise, consist of, or be comprised in a control system configured to control charging on an energy storage device of a vehicle during a charging procedure in accordance with the present disclosure; and Fig. 6 schematically illustrates an RC equivalent circuit model of an energy storage device.

DETAILED DESCRIPTION The invention will be described in more detail below with reference to exemplifying embodiments and the accompanying drawings. The invention is however not limited to the exemplifying embodiments discussed and/or shown in the drawings, but may be varied within the scope of the appended claims. Furthermore, the drawings shall not be considered drawn to scale as some features may be exaggerated in order to more clearly illustrate the invention or features thereof. ln accordance with the present disclosure, a method for controlling charging of an energy storage device of a vehicle during a charging procedure is provided. The present method is primarily developed for controlling charging of an energy storage device of a vehicle during a charging procedure at a charging station. However, the method may also be used for controlling charging of an energy storage device of a vehicle during a charging procedure when the vehicle is temporarily present within a charging zone.

A charging station is in the present disclosure considered to mean a place at which the vehicle is intended to be stationary during the charging procedure, such as at a vehicle depot, at a parking place, or at a bus stop. ln contrast, a charging zone is in the present disclosure considered to mean a section of a road comprising infrastructure allowing the energy storage device of the vehicle to be connected to an electrical grid for the purpose of charging the energy storage device. The connection to the electrical grid may for example be made by a current collector of the vehicle connecting to overhead lines or an electrical track/rail arranged at the side of, or in, the section of the road. ln other words, the vehicle is in the latter case temporarily present in the charging zone, and in motion, during the charging procedure of the energy storage device.

Furthermore, in the present disclosure, the terms first charging station or charging zone and second charging station or charging zone are used to distinguish between a charging station/charging zone where the charging procedure is to be performed and a charging station/charging zone where a subsequent charging procedure may be performed. lt should here be noted that in reality, the second charging station/charging zone may in some cases in fact be the same charging station/charging zone as the first charging station/charging zone in case the vehicle would, when completing an intended route, be returned to the same charging station or charging zone.

The herein described method for controlling charging of an energy storage device of a vehicle during a charging procedure comprises a step of, based on a predicted desired amount of charging energy by which the energy storage device is to be charged during the charging procedure and a predetermined allowable duration for the charging procedure, determining a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device so as to reduce the risk of aging of the energy storage device. Said charging profile defines the charging current, and the temperature of the energy storage device, over time. The method further comprises charging the energy storage device while controlling the charging current and the temperature of the energy storage device in accordance with the determined charging profile. ln other words, the method comprises controlling the charging of the energy storage device during the charging procedure in accordance with the determined charging profile.

As described above, the method comprises determining a charging profile for the charging procedure based on e.g. a predetermined allowable duration for the charging procedure. The predetermined allowable duration for the charging procedure may typically correspond to the time the vehicle may remain at the charging station, for example in dependence of a scheduled timetable for the operation of the vehicle or in dependence of expected duration for unloading and/or loading of the vehicle intended to be performed when the vehicle is present at the charging station at which the charging procedure is to be performed. The predetermined allowable duration for the charging procedure may alternatively, or additionally, be dependent on a restriction of the charging station, e.g. specifying a maximum allowable duration for each charging procedure at said charging station. Alternatively, the predetermined duration for the charging procedure may correspond to the time the vehicle is expected to remain within the charging zone. The latter may for example be determined in dependence of expected driving conditions of the vehicle when present within the charging zone.

The method may further comprise a step of predicting the desired amount of charging energy by which the energy storage device is to be charged during the charging procedure. This may be performed based on the current state of charge of energy storage device and a predicted state of charge of the energy storage device required for the vehicle to travel from a first charging station or charging zone, at which the charging procedure is to be performed, to a second charging station or charging zone, where a subsequent charging procedure may be performed. Optionally, a pre- selected offset state of charge may also be considered when predicting the desired amount of charging energy by which the energy storage device is to be charged during the charging procedure. The pre-selected offset state of charge may typically be a pre-selected offset state of charge for the purpose of having a safety margin to account for unexpected circumstances, which may require more power from the energy storage device, during the travel of the vehicle from the first charging station or charging zone to the second charging station or charging zone. ln other words, the predicted desired amount of charge by which the energy storage device is to be charged may according to a first alternative be the state of charge required for the vehicle to reach a second charging station or charging zone where a subsequent charging procedure may be performed minus the current charge of the energy storage device before charging the energy storage device at the first charging station or charging zone. According to this alternative, the predicted desired amount of charge by which the energy storage device is to be charged may alternatively be described as the predicted required amount of charge by which the energy storage device is to be charged during the charging procedure. Alternatively, the predicted desired amount of charge by which the energy storage device is to be charged may according to a second alternative be the state of charge required for the vehicle to reach a second charging station or charging zone where a subsequent charging procedure may be performed, plus a preselected offset state of charge (to account for unexpected circumstances), minus the current charge of the energy storage device before charging the energy storage device at the first charging station or charging zone. The second alternative would thus lead to a higher predicted desired amount of charge by which the energy storage device is to be charged during the charging procedure compared to the first alternative.

The method may further comprise a step of predicting a state of charge of the energy storage device required for the vehicle to travel from the first charging station or charging zone (at which the charging procedure is to be performed) to the second charging station or charging zone (at which a subsequent charging procedure may be performed). Said prediction may be made based on geographical data relating to an (upcoming) route of the vehicle from the first charging station or charging zone to the second charging station or charging zone. Such geographical data relating to the route of the vehicle may typically comprise distance, topography and/or curvature of the road of the route. The geographical data relating to the upcoming route of the vehicle may be derived in accordance with any previously known method therefore and will therefore not be further described in the present disclosure. Additional parameters, such as vehicle configuration, vehicle load, driving mode of the vehicle, weather conditions, traffic conditions etc., may also be considered when predicting the state of charge of the energy storage device required for the vehicle to travel from the first charging station/ charging zone to the second charging station/charging zone. The ski||ed person is well aware of methods for deriving data re|ating to such parameters and how to use these for prediction of power consumption from an energy storage device of a vehicle, and this will therefore not be further discussed in the present disclosure.

Alternatively or additionally, the prediction of the state of charge of the energy storage device required for the vehicle to travel from the first charging station or charging zone (at which the charging procedure is to be performed) to the second charging station or charging zone (at which a subsequent charging procedure may be performed) may be performed based on historical data regarding energy consumption from an energy storage device for travel of the vehicle and/or other vehicles traveling the same route from the first charging station or charging zone to the second charging station or charging zone. Such historical data may be stored by the control system and/or retrieved from a remote source, such as from a remote control center or the like.

As previously mentioned, the method comprises determining a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device so as to reduce the risk of aging of the energy storage device. Said predetermined aging model may consider various aging factors. Preferably, the aging model for the energy storage device comprises at least a model for solid electrolyte interface formation and/or a model for lithium plating in the energy storage device.

More specifically, the charging profile is derived by minimizing the aging speed of the energy storage device, subject to the following constraints (i)-(v): (i) configuration of the energy storage device defined by a model of the energy storage device, (ii) a thermal model of the energy storage device, (iii) a charging current limitation from the charging station or charging zone (which is also dependent of limitations from the electrical grid to which the charging station or charging zone is connected), (iv) the amount of charging energy to be supplied to the energy storage device during the charging procedure, and (v) allowable duration for the charging procedure. 11 The configuration of the energy storage device may be modelled using various methods known in the art. An overview of different ways to model an energy storage device may be found in Marian Tomasov et al. "Overview of Battery Models for Sustainable Power and Transport Applications", Transportation Research Procedia 40 (2019) 548-555. Such models of an energy storage device may be used to predict the characteristics of the energy storage device.

For example, the energy storage device may be modelled using a RC equivalent circuit model, such as exemplified in Equation 1. Figure 6 schematically illustrates such a RC equivalent circuit model of an energy storage device. ln Equation 1, up is the change in voltage, up is the polarized voltage, R is the resistance, C is capacitance, I is the current, rsoc is the state of charge, um, is the open circuit voltage (and is a function of rsoc), RO is the internal resistance, and Qwp is the capacity of the energy storage device. n I up _ E E EC|. 1 T._ I soc Qcap u' = up + ROI + uocvÛ-soc) The thermal model of the energy storage device is dependent of the configuration of the energy storage device. ln its most simple form, it may be described in accordance with Equation 2, wherein Tis the change in temperature of the energy storage device, T is the temperature of the energy storage device, and a and b are constants dependent of the configuration of the energy storage device. lt should here be noted that the temperature of the energy storage device is dependent of several factors, such as the temperature of the surrounding environment, the temperature of a coolant of the energy storage device, the heat provided to the energy storage device by a heater of the energy storage device, as well as the operating condition of the energy storage device. The Qcll-mate is the energy input to the energy storage device considering environment, coolant and heat provided to the energy storage device, and heat generated in the energy storage device. These factors may all be incorporated into the thermal model of the energy storage device.

T = aT + b Qclimate Eq- 2 12 The charging current limitation from the charging station or charging zone is the maximum charging current Ireq which may be provided by the charging station or charging zone to the energy storage device. Thus, the charging current I must always be equal to or lower than Ireq.

The amount of charging energy Q to be supplied to the energy storage device during the charging procedure corresponds to the predicted desired amount of charging energy by which the energy storage device is to be charged during the charging procedure as previously described, and must always be equal to or higher than the necessary amount of charging energy Qreq to be supplied to the energy storage device during the charging procedure. The necessary amount of charging energy Qreq to be supplied to the energy storage device during the charging procedure corresponds to the above-described required state of charge of the energy storage device for the vehicle to travel from the first charging station or charging zone to the second charging station or charging zone minus the current state of charge of the energy storage device.

Furthermore, the duration t of the charging procedure must always be equal to or less than the predetermined allowable duration treq for the charging procedure. Suitably, the duration t of the charging procedure should in most cases be equal to or as close as possible to the predetermined allowable duration treq for the charging procedure. The predetermined allowable duration for the charging procedure may, as described above, correspond to the time the vehicle may remain at the charging station or within the charging zone where the charging procedure is to be performed.

Based on the above explained constraints, and the aging model of the energy storage device, the charging profile may be determined by minimizing Equation 3. f = faging (upv u[t15 tendL T[t15 tendLIU-Ll: tendD Eq- 3 Equation 3 predict the aging speed of the energy storage device based on different input during period of tl: tend. The time period may be selected as desired. However, the period selection will influence the accuracy in the result and the longer the better. Equation 3 may be iterated and thus solved for every time unit (period) of the intended charging process. Thereby, a charging profile defining charging current and temperature of the energy storage device over time may be achieved.

There are various aging models for energy storage devices previously proposed in the art. These models may be verified by laboratory experiments for a specific energy storage device in order to 13 verify their accuracy. Different aging models may for example take into consideration aging factors such as solid electrolyte interphase (SEI) formation and lithium plating. Examples of aging models for energy storage devices are described in Evelina Wikner, "Lithium ion Battery Aging: Battery Lifetime and Physics-based Modeling for Electric Vehicle Applications", Thesis for the Degree of Licentiate of Engineering, Department of Electrical Engineering, Chalmers University of Technology, 2017. Keii, Jonas, and Andreas Jossan. "Electrochefnical lvlodellfig of Linear ana' Norillfiear Aging of Lithltffn-lon Calls." ,Journal of The Electrooheniical Society 'löïfl no. 11 (2629): 11G535.

As previously mentioned, the method comprises charging the energy storage device while controlling the charging current and the temperature of the energy storage device in accordance with the determined charging profile. The control of the temperature of the energy storage device during the charging procedure may be performed by controlling the temperature of a coolant of the energy storage device and/or by controlling a heater configured to heat the energy storage device depending on the circumstances.

The method may further comprise monitoring the charging procedure for the purpose of ensuring that the determined charging profile is followed and/or that the energy storage device is charged as expected. This may for example be performed by monitoring the charging current and the temperature of the energy storage device over time. Optionally, the state of charge of the energy storage device may also be monitored over time during the charging procedure. Said monitoring may enable detecting deviations from the determined charging profile, either by directly detecting that the predetermined charging profile is not followed or indirectly by detecting that the state of charge of the energy storage device is not changed as expected during the charging procedure. The method may further comprise, in response to such a detection of a deviation from the determined charging profile for the charging procedure, determining a revised charging profile for the remaining portion of the charging procedure. Such a revised charging profile may define charging current and temperature of the energy storage device over time. Thereafter, the method may comprise charging the energy storage device in accordance with the revised charging profile.

The energy storage device may comprise or consist of a lithium-ion secondary energy storage device. The present method may be used for any previously known lithium-ion secondary energy storage device intended for use in a vehicle, in particular energy storage devices configured for powering an electrical machine of a vehicle for the purpose of propulsion of the vehicle. Moreover, the energy storage device may comprise a pack of batteries, such as a pack of lithium-ion secondary batteries. 14 The performance of the herein described method controlling charging of an energy storage device of a vehicle during a charging procedure may be governed by programmed instructions. These programmed instructions typically take the form of a computer program which, when executed in or by a control system, cause the control system to effect desired forms of control action. Such instructions may typically be stored on a computer-readable medium.

The present disclosure further relates to a control system configured to control charging of an energy storage device of a vehicle during a charging procedure, in particular in accordance with the above- described method. The control system may be configured to perform any one of the steps of the herein described method for controlling charging of an energy storage device of a vehicle during a charging procedure.

More specifically, the present disclosure provides a control system configured to control charging of an energy storage device of a vehicle during a charging procedure. The control system is configured to, based on a predicted desired amount of charging energy by which the energy storage device is to be charged during the charging procedure and a predetermined allowable duration for the charging procedure, determine a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device so as to reduce the risk of aging of the energy storage device, wherein said charging profile defines charging current and temperature of the energy storage device over time. The control system is further configured to charge the energy storage device while controlling the charging current and the temperature of the energy storage device in accordance with the determined charging profile.

The control system may comprise a plurality of control units. Each control unit may be configured to control one or more functions or a certain function may be divided between different control units. One or more of the control units of the control system may be arranged in the vehicle, and thus be a part of the vehicle as such. Moreover, one or more control units of the control system may be arranged outside of the vehicle, for example at a charging station or at a charging zone. Furthermore, one or more control units of the control system may, if desired, be arranged remote from the vehicle and the charging station/charging zone, such as at a remote control center or the like.

According to an exemplifying embodiment, the control system comprises a charging unit, a temperature control unit and a control device. The charging unit may be configured to provide a charging current to the energy storage device. The charging unit may for example be arranged at a charging station or at a charging zone. The temperature control unit may be configured to control the temperature of a coolant of the energy storage device and/or a heater configured to heat the energy storage device. Such a temperature control unit may for example be arranged in the vehicle. Furthermore, the control device may be configured to control the charging current provided by the charging unit to the energy storage device and, by usage of the temperature control unit, the temperature of the energy storage device in accordance with the determined charging profile.

The present disclosure further provides a system comprising a vehicle comprising an energy storage device, at least one charging station or charging zone where the energy storage device of the vehicle may be charged and the above-described control system configured to control charging of an energy storage device of a vehicle during a charging procedure. The vehicle may be a land-based heavy vehicle, such as a truck or a bus, but is not limited thereto. The vehicle may be a fully electrical vehicle or a hybrid vehicle.

Figure 1 illustrates one example of a vehicle 1, here shown as a bus, present at a charging station 2. The vehicle comprises a current collector, here illustrated as being in the form of a pantograph 3, configured to allow the vehicle 1 to be connected to the charging station 2 for the purpose of charging an energy storage device 4 (schematically illustrated in the figure by dashed lines) onboard the vehicle 1. The energy storage device 4 of a vehicle 1 may comprise a pack of batteries, usually lithium-ion batteries. Each battery may in turn generally comprise a plurality of individual electrochemical cells.

Figure 2 schematically illustrates a cross sectional view of one example of an electrochemical cell 5 of an energy storage device, such as an energy storage device 4 of the vehicle 1 shown in figure 1. The electrochemical cell 2 comprises an anode 6 connected to a first current collector 7. The anode may be formed of a porous structure of a first electroactive material 6a, such as a carbonaceous material. The electrochemical cell 2 further comprises a cathode 8 connected to a second current collector 9. The cathode may be formed of a porous structure of a second electroactive material 8a, such as a lithium ion containing material. A separator 10 is interposed between the anode 6 and the cathode 8. The electrochemical cell 5 further comprises an electrolyte (not shown). The electrolyte may be present within the porous structures of the anode 6 and the cathode 8, as well as the separator 10. The first and second current collectors 7, 9 may in turn be connected to a load (during discharging) or charger (during charging). The load/charger is illustrated in Figure 2 by the box 11.

Generally, there is a desire to be able to charge an energy storage device of a vehicle as fast as possible in order to limit the time the vehicle may be out of service due to a charging procedure. 16 However, a challenge with fast charging is the complex electrochemical reactions which occur in the electrochemical cells of the energy storage device during the charging process. A fast charging of an energy storage device may affect its functionality and accelerate the aging process.

There are various factors that may lead to aging of an electrochemical cell 5, and thus also aging of the energy storage device 4 comprising said electrochemical cell. For example, a capacity loss can occur due to degradation of the electrolyte components through side reactions with lithium ions with the result of less cyclable lithium ions. Furthermore, there may be a loss of active electrode material in the electrodes. Power losses can also occur due to contact resistance in the interphases between the materials, growth of resistive film on the electrode active material, loss of active surface area and impaired mass transport.

One example of a specific aging mechanism is the formation of a solid electrolyte interphase (SEI) on the active material of the anode. The SEI is a passivated surface layer on the active material and will form already at the first charge/discharge cycle of the electrochemical cell 5. The following growth of the SEI layer is a function of different factors, such as number of operating cycles, temperature and constituent materials. Another example of a specific aging mechanism is metallic lithium plating of the anode. This aging mechanism is affected by for example the operating temperature and the charge rate.

Figure 3 represents a flowchart schematically illustrating one exemplifying embodiment of the herein described method for controlling charging of an energy storage device of a vehicle during a charging procedure. ln the figure, optional steps are illustrated by dashed boxes. Such steps may be replaced by retrieving the corresponding data derived in the respective steps from other sources.

The method may comprise a step S101 of predicting a state of charge of the energy storage device required for the vehicle to travel from a first charging station/charging zone at (which the charging procedure is to be performed) to a second charging station or charging zone (where a subsequent charging procedure may be performed. Said prediction may be made based on geographical data relating to a predefined route of the vehicle from the first charging station or charging zone to the second charging station or charging zone. Alternatively, said prediction may be made based on historical data relating to previous occasions the vehicle has travelled the same route.

The method may further comprise a step S102 of predicting a desired amount of charging energy by which the energy storage device is to be charged during the charging procedure. The desired amount 17 of charging energy may be predicted based on a current state of charge of the energy storage device, a predicted state of charge of the energy storage device required for the vehicle the first charging station or charging zone to the second charging station or charging zone as derived in step S101, and optionally a pre-selected offset state of charge. The offset state of charge may be intended to provide a safety margin to account for unexpected circumstances during the travel of the vehicle from the first to the second charging station or charging zone.

The method comprises a step S103 of determining a charging profile for the charging procedure. Said charging profile defines the charging current, as well as the temperature, over time during the upcoming charging procedure. The charging profile is determined, based on a predicted desired amount of charging energy by which the energy storage device is to be charged and a predetermined allowable duration for the charging procedure, in consideration of a predetermined aging model for the energy storage device. The predicted desired amount of charging energy by which the storage device is to be charged may be obtained from step S102 or, if the method does not comprise step S102, from a control device remote from the control system.

The method further comprises a step S104 of charging the energy storage device while controlling the charging current and the temperature of the energy storage device in accordance with the determined charging profile. ln other words, the method comprises performing the charging procedure while controlling the charging current and the temperature of the energy storage device according to the determined charging profile.

Figure 4 schematically illustrates one exemplifying embodiment of a control system 100 configured to control charging of an energy storage device of a vehicle during a charging procedure in accordance with the present disclosure. The control system 100 may comprise a plurality of control units and/or control devices, as shown in the figure. Such control units/devices are configured to communicate with each other within the control system 100. The communication may be performed in accordance with any previously known method as known in the art, such as by wireless communication.

The control system 100 comprises a control device 110 configured to control charging of an energy storage device during a charging procedure in accordance with a determined charging profile. More specifically, the control device 110 may be configured to control the charging current provided by a charging unit 120 of a charging station or charging zone. Furthermore, the control device 110 is configured to control the temperature of the energy storage device by usage of a temperature 18 control unit 130. Said temperature control unit 130 may in turn be configured to control the temperature of a coolant of the energy storage device and/or a heater configured to heat the energy storage device.

The control device 110 may further be configured to determine a charging profile for a charging procedure in consideration of a predetermined aging model for the energy storage device based on a predicted desired amount of charging energy by which the energy storage device is to be charged during the charging procedure and a predetermined allowable duration for the charging procedure. For said purpose, the control device 110 may be configured to retrieve data from a prediction control unit 140. Said prediction control unit 140 may be a part of the control system 100 or be remote from the control system 100. The prediction control unit 140 is configured to predict a desired amount of charging energy by which the energy storage device is to be charged during the charging procedure. The control device 110 may further be configured to retrieve data from a control unit 150 configured to determine allowable duration for a charging procedure. The control unit 150 may be comprised in the control system 100 or be remote from the control system 100.

Moreover, the control device 110 may for the purpose of determining the charging profile be configured to retrieve various models of the energy storage device from a modeling control unit 160. Such models may include a model of the configuration of the energy storage device, a thermal model of the energy storage device and an aging model of the energy storage device. The modeling unit 160 may be a part of the control system 100 or be remote from the control system 100.

The control device 110 may further be configured to retrieve further data from further control units, such as the temperature of the surrounding environment of the energy storage device from a climate control unit 170. The control device 110 may be configured to take into account such further data when determining the charging profile for the charging procedure.

Figure 5 schematically illustrates an exemplifying embodiment of a device 500. The control system 100 described above may for example comprise the device 500, consist of the device 500, or be comprised in the device 500.

The device 500 comprises a non-volatile memory 520, a data processing unit 510 and a read/write memory 550. The non-volatile memory 520 has a first memory element 530 in which a computer program, e.g. an operating system, is stored for controlling the function of the device 500. The device 500 further comprises a bus controller, a serial communication port, I/O means, an A/D converter, a 19 time and date input and transfer unit, an event counter and an interruption controller (not depicted).

The non-volatile memory 520 has also a second memory element 540.

There is provided a computer program P that comprises instructions for controlling charging of an energy storage device of a vehicle during a charging procedure. The computer program comprises instructions for, based on a predicted desired amount of charging energy by which the energy storage device is to be charged during the charging procedure and a predetermined allowable duration for the charging procedure, determining a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device so as to reduce the risk of aging of the energy storage device. Said charging profile defines charging current and temperature of the energy storage device over time. The computer program further comprises instructions for charging the energy storage device while controlling the charging current and the temperature of the energy storage device in accordance with the determined charging profile.

The program P may be stored in an executable form or in a compressed form in a memory 560 and/or in a read/write memory 550.

The data processing unit 510 may perform one or more functions, i.e. the data processing unit 510 may effect a certain part of the program P stored in the memory 560 or a certain part of the program P stored in the read/write memory 550.

The data processing device 510 can communicate with a data port 599 via a data bus 515. The non- volatile memory 520 is intended for communication with the data processing unit 510 via a data bus 512. The separate memory 560 is intended to communicate with the data processing unit 510 via a data bus 511. The read/write memory 550 is adapted to communicate with the data processing unit 510 via a data bus 514. The communication between the constituent components may be implemented by a communication link. A communication link may be a physical connection such as an optoelectronic communication line, or a non-physical connection such as a wireless connection, e.g. a radio link or microwave link.

When data are received on the data port 599, they may be stored temporarily in the second memory element 540. When input data received have been temporarily stored, the data processing unit 510 is prepared to effect code execution as described above.

Parts of the methods herein described may be affected by the device 500 by means of the data processing unit 510 which runs the program stored in the memory 560 or the read/write memory 550. When the device 500 runs the program, methods herein described are executed.

Claims (1)

1.A method, performed by a control system (100), for controlling charging of an energy storage device (4) of a vehicle (1) during a charging procedure, the method comprising the following steps: based on a predicted desired amount of charging energy by which the energy storage device (4) is to be charged during the charging procedure and a predetermined allowable duration for the charging procedure, determining a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device (4) so as to reduce the risk of aging of the energy storage device (4), wherein said charging profile defines charging current and temperature of the energy storage device (4) over time, and charging the energy storage device (4) while controlling the charging current and the temperature of the energy storage device (4) in accordance with the determined charging profile. The method according to claim 1, further comprising a step of predicting (S102) a desired amount of charging energy by which the energy storage device (4) is to be charged during the charging procedure based on a current state of charge of the energy storage device (4), a predicted state of charge of the energy storage device (4) required for the vehicle (1) to travel from a first charging station (2) or charging zone at which the charging procedure is to be performed to a second charging station or charging zone where a subsequent charging procedure may be performed, and optionally a pre- selected offset state of charge. The method according to claim 2, further comprising a step of: predicting (S101) a state of charge of the energy storage device (4) required for the vehicle to travel from the first charging station (2) or charging zone to the second charging station or charging zone based on geographical data relating to a route of the vehicle (1) from the first charging station (2) or charging zone to the second charging station or charging ZOne. The method according to any one of the preceding claims, wherein the predetermined aging model comprises a model for solid electrolyte interphase formation and/or a model for lithium plating in the energy storage device (4).The method according to any one of the preceding claims, wherein said contro||ing of the temperature of the energy storage device (4) in accordance with the determined charging profile comprises contro||ing the temperature of a coo|ant of the energy storage device (4) and/or contro||ing a heater configured to heat the energy storage device (4). The method according to any one of the preceding claims, further comprising: monitoring the charging procedure, and in response to a detection of a deviation from the determined charging profile for the charging procedure, determining a revised charging profile for a remaining portion of the charging procedure. The method according to any one of the preceding claims, wherein the energy storage device (4) comprises a lithium-ion secondary energy storage device. A computer program comprising instructions which, when executed by a control system (100), cause the control system (100) to carry out the method according to any one of the preceding claims. A computer-readable medium comprising instructions which, when executed by a control system (100), cause the control system (100) to carry out the method according to any one of claims 1 to A control system (100) configured to control charging of an energy storage device (4) of a vehicle (1) during a charging procedure, wherein the control system (100) is configured to: based on a predicted desired amount of charging energy by which the energy storage device (4) is to be charged during the charging procedure and a predetermined allowable duration for the charging procedure, determine a charging profile for the charging procedure in consideration of a predetermined aging model for the energy storage device (4) so as to reduce the risk of aging of the energy storage device (4), wherein said charging profile defines charging current and temperature of the energy storage device (4) over time, and charge the energy storage device (4) while contro||ing the charging current and the temperature of the energy storage device in accordance with the determined charging profile.The control system (100) according to claim 10, further configured to predict a desired amount of charging energy by which the energy storage device (4) is to be charged during the charging procedure based on a current state of charge of the energy storage device (4), a predicted state of charge of the energy storage device (4) required for the vehicle (1) to travel from a first charging station (2) or charging zone at which the charging procedure is to be performed to a second charging station or charging zone where a subsequent charging procedure may be performed, and optionally a pre- selected offset state of charge. The control system (100) according to any one of c|aims 10 or 11, comprising: a charging unit (120) configured to provide a charging current to the energy storage device (4), a temperature control unit (130) configured to control the temperature of a coolant of the energy storage device and/or a heater configured to heat the energy storage device, and a control device (110) configured to control the charging current provided by the charging unit to the energy storage device and, by usage of the temperature control unit, the temperature of the energy storage device in accordance with the determined charging profile. A system comprising: a vehicle (1) comprising an energy storage device (4), at least one charging station (2) or charging zone where the energy storage device (4) may be charged, and a control system (100) configured to control charging of an energy storage device (4) of a vehicle (1) during a charging procedure according to any one of c|aims 10 to 12.