SE542827C2

SE542827C2 - Method and control device for controlling energy levels of energy storage devices in a vehicle

Info

Publication number: SE542827C2
Application number: SE1851161A
Authority: SE
Inventors: André Claesson; Linus Ährlig; Mikko Kallio; Morgan Colling; Robert Sjödin; Sami Teppola; Tomas Skeppström
Original assignee: Scania Cv Ab
Priority date: 2018-09-28
Filing date: 2018-09-28
Publication date: 2020-07-14
Also published as: DE112019004903T5; CN112770931A; WO2020067948A1; SE1851161A1

Abstract

The present disclosure relates to techniques in the context of vehicles, and to a method for controlling energy levels of energy storage devices (70) in a vehicle (1) comprising a plurality of drive modules (30). According to a first aspect, the disclosure relates to a method for controlling energy levels of energy storage devices (70) in a vehicle (1) comprising a plurality of drive modules (30), wherein each drive module (30) comprises an individual propulsion system (91) operable to propel the vehicle (1) and a chargeable energy storage device (70) arranged to supply energy to the propulsion system (91). The method comprises determining (S1) energy levels of the chargeable energy storage devices (70) of the plurality of drive modules (30), controlling (S2) operation of the individual drive modules (30), while operating the vehicle (1), based on the determined energy levels. The disclosure also relates to a corresponding control device (200), to a vehicle (1) comprising the control device (200), to a computer program and a computerreadable medium.

Description

Method and control device for controlling energy levels of energy storage devices in a vehicle Technical field The present disclosure relates to techniques in the context of vehicles, and to a method for controlling energy levels of energy storage devices in a vehicle comprising a plurality of drive modules. The disclosure also relates to a corresponding control device, to a vehicle comprising the control device, to a computer program and a computer-readable medium.

Background Vehicles of today are typically manufactured for a specific purpose, e.g. a bus is manufactured for transporting people and a truck is manufactured for transporting goods. Such vehicles are commonly manufactured and completely assembled in a factory, or they may be partly assembled in a factory and completed at a body manufacturer. Once the vehicle is assembled, the vehicle may be used for the specific purpose. Thus, a bus may be used as a bus and a garbage truck may be used as a garbage truck. Different vehicles are thus needed for different purposes, which may require a large fleet of vehicles for a hauler, and thereby become very costly.

There are, for example, known solutions where a truck can be rebuilt by changing a concrete mixer to a loading platform. This increases the flexibility and two different functions can be achieved by means of one single vehicle. Also, document US-2016/0129958 A1 discloses a modular electric vehicle using interchangeable vehicle assembly modules. The user can thereby disassemble and reassemble the vehicle for use in different applications. However, in the future, further development towards even more flexible vehicle solutions might be needed to meet customers’ different vehicle needs in a cost-efficient way.

Summary It is an object of the disclosure to provide a solution that makes it possible to control operation of a modular vehicle while ensuring that the individual modules of the vehicle always comprise enough energy to perform an assigned mission. It is also an object, of some embodiments, to provide a method for operating a modular vehicle that ascertains that (if possible) an individual energy storage device of the vehicle is not completely discharged.

According to a first aspect, the disclosure relates to a method for controlling energy levels of energy storage devices in a vehicle comprising a plurality of drive modules, wherein each drive module comprises an individual propulsion system operable to propel the vehicle and a chargeable energy storage device arranged to supply energy to the propulsion system. The method comprises determining energy levels of the chargeable energy storage devices of the plurality of drive modules and controlling operation of the individual drive modules, while operating the vehicle, based on the determined energy levels. Thereby, it is possible to obtain an even distribution of the energy levels of the energy storage devices of a modular vehicle.

In some embodiments, the controlling of operation of an individual drive module comprises controlling the propulsion system of the drive module to propel the vehicle, whereby the energy level of the corresponding energy storage device is decreased. Thereby, only energy storage devices with a significant energy level will be used to propel the vehicle.

In some embodiments, the controlling of operation of an individual drive module comprises controlling the propulsion system of the drive module to operate as a generator, whereby the energy level of the corresponding energy storage device is increased. Thereby, superfluous energy will be used to charge drive modules with a low charging level.

In some embodiments, the controlling of operation of an individual drive module comprises controlling the propulsion system of the drive module to be deactivated. Thereby, drive modules having a low charging level will never be used.

In some embodiments, the controlling comprises controlling operation of the drive modules to balance the individual energy levels of the chargeable energy storage devices among the drive modules. Hence, an even distribution of the energy levels of the drive modules is obtained.

In some embodiments, the controlling comprises distributing energy outtake among the energy storage devices drive modules such that their individual energy levels do not go below a predetermined minimum energy level. Thereby, it is assured that an individual drive module is not discharged.

In some embodiments, the chargeable energy storage devices of the drive modules have individually different energy levels and the controlling comprises propelling the vehicle using one or more of the drive modules having the highest energy levels among the drive modules. Thereby, the energy levels of the drive modules are equalized while propelling the vehicle.

In some embodiments, the chargeable energy storage devices of the drive modules have individually different energy levels and the controlling comprises operating one or more of the drive modules having the lowest energy levels among the drive modules as generators, to charge their corresponding energy storage devices. Thereby, the energy levels of the drive modules are equalized while braking the vehicle.

In some embodiments, the controlling comprises transferring energy between energy storage devices of the different drive modules by operating at least one of the drive modules as a generator while propelling the vehicle using at least one of the other drive modules. Thereby, energy can be transferred between the drive modules via the wheels.

In some embodiments, the transferring is triggered by one or more of the energy storage devices of a drive module having an energy level below a predetermined threshold. Thereby, the transfer may only be used when required for safe operation.

According to a second aspect the disclosure relates to a corresponding a control device for use in a vehicle comprising a plurality of drive modules, wherein each drive module comprises an individual propulsion system operable to propel the vehicle and a chargeable energy storage device arranged to supply energy to the propulsion system. The control device being configured to determine energy levels of the chargeable energy storage devices of the plurality of drive modules, and controlling operation of the individual drive modules, while operating the vehicle, based on the determined energy levels.

In some embodiments, the control device is configured to perform the method according to any of the embodiments of the first aspect.

In some embodiments, the control device is comprised in one of the drive modules which is assigned to be a master drive module of the vehicle and wherein the other drive modules are slave drive modules.

According to a third aspect, the disclosure relates to a vehicle comprising a plurality of drive modules, wherein each drive module comprises a propulsion system and a chargeable energy storage device arranged to supply energy to the propulsion system, and the control device according to the second aspect.

According to a fourth aspect, the disclosure relates to a computer program comprising instructions which, when the program is executed by a computer, cause the computer to carry out the method according to the first aspect.

According to a fifth aspect, the disclosure relates to a computer-readable medium comprising instructions which, when executed by a computer, cause the computer to carry out the method according to the first aspect.

Brief description of the drawings Fig. 1 illustrates a set of modules, a vehicle assembled from the set of modules, and an offboard system.

Fig. 2a - Fig. 2c schematically illustrate a drive module in a side view, a front view and in a view from above.

Fig. 3 schematically illustrates a drive module in further detail.

Fig. 4 illustrates a method for controlling energy levels of energy storage devices in a vehicle according to the first aspect.

Fig. 5 illustrates an example implementation of a control device according to the second aspect.

Detailed description One way of meeting customers’ different vehicle needs in a flexible and costefficient way is to use a modularised vehicle assembled from a set of modules. Such a modularised vehicle, herein referred to as a modular vehicle, is typically assembled at the customer’s premises and the customer may thus buy a set of modules from a manufacturer. The modular vehicle can easily be assembled and re-assembled e.g. to perform a certain mission.

A modular vehicle is e.g. assembled by functional modules for performing a certain function (such as carrying a load) and drive modules used for driving the vehicle. Each drive module typically comprises an individual propulsion system and an individual energy storage device, such as a battery. To make the modules together act as one modular vehicle, the control of the drive modules must be coordinated in some way.

To assemble and disassemble a modular vehicle, the drive modules may be required to transport themselves to and from the functional modules. However, if the batteries of one or more of the drive modules are discharged, then those drive modules will not be able to transport themselves between the functional modules. Furthermore, in some scenarios, it may be required that an assembled vehicle is propelled by all its wheels. If one of the drive modules is discharged, then this will not be possible. Hence, it is generally desirable to maintain the power levels of the individual drive modules of a modular at about the same level.

A method is herein proposed, whereby the outtake of energy from, and also charging of, the energy storage devices of the drive modules in a modular vehicle is controlled based on their present energy content, herein referred to as energy level. More specifically, it is herein proposed that while operating a modular vehicle the current energy (or charging) levels of the energy storage devices of the individual drive modules are considered. Thereby, it is in general possible to avoid that one individual energy storage is completely discharged. This is for example achieved by using one or more drive modules having a fully (or at least sufficiently) charged energy storage to propel the vehicle or by using power generated when braking the modular vehicle to charge energy storage devices that have a low energy level.

For better understanding of the proposed technique the concept of assembling a vehicle from modules will now be explains with reference to the example embodiment of Fig. 1.

Fig. 1 illustrates an example set of modules 20 for assembling a vehicle 1. An offboard system, herein referred to as a first control device 100, and an example of an assembled vehicle 1 are also illustrated. The set of modules 20 comprises a plurality of drive modules 30 and a plurality of functional modules 40.

The drive modules’ 30 main function is typically to drive (e.g. propel, steer and brake) a vehicle 1. The drive modules 30 comprise a pair of wheels 37 and are configured to be autonomously operated. The functional modules are configured to perform a certain function such as to carry a load, e.g. goods or people. Each module 30, 40 in the set of modules 20 comprises at least one interface 50 releasably connectable to a corresponding interface 50 of another module 30, 40.

By combining drive modules 30 and functional modules 40 different types of vehicles 1 can be achieved. Some vehicles 1 require two or more drive modules 30 and some vehicles 1 only require one drive module 30, depending on the structural configuration of the functional module 40. Each drive module 30 comprises a control device, herein referred to as a second control device 200, and may thus communicate with a control center or off-board system, i.e. the first control device 100. Since the drive modules 30 may be configured to be operated as independently driven units by means of the second control devices 200, the drive modules 30 may be connected to, or disconnected from, the functional module(s) 40 without manual work.

The principle of assembling a vehicle 1 from modules 30, 40 will now be described. An operator may receive a mission from a client to transport goods from one location to another. The operator enters the information about the mission into the first control device 100 via a user interface, such as a touch screen or similar. It is pointed out that this is merely an example, and the received mission may automatically be translated and/or inputted to the first control device 100. The first control device 100 then determines which function to be performed and thus which type of vehicle 1 is required to complete the mission. In this example, the required vehicle 1 may be a truck. The first control device 100 selects which modules 30, 40 to use for the required truck. The type of vehicle 1 and the modules 30, 40 required to complete the mission may for example be selected based on information about the goods, the distance to travel and/or the geographical location. The first control device 100 then converts the mission into a command for one or two selected drive modules 30 to physically and electrically connect with the selected functional module 40. In this example, the vehicle 1 comprises two drive modules. The second control devices 200 of the drive modules 30 each receives the command and converts the command to control signals for the respective drive module 30. The drive modules 30 are thereby controlled to physically and electrically connect with the functional module 40. Controlling the drive module 30 to connect with a functional module 40 may comprise controlling the drive module 30 to identify the position of the selected functional module 40 and move to that position. The position of the selected functional module 40 may be determined based on information received in the command to connect the drive module 30 with the functional module 40. Alternatively, the command to connect the drive module 30 and the functional module 40 is transmitted to both the drive module 30 and the functional module 40, whereby the functional module 40 prepares for the connection and starts transmitting a signal. The drive module 30 may then determine the position of the functional module based on this transmitted signal. The drive modules 30 are thus autonomously operated to find the selected functional module 40 and connect with that functional module 40. At least one sensor device 60 arranged at the drive modules 30 and/or the functional module 40 may be configured to sense when the physical and/or electrical connection has been performed. The at least one sensor device 60 may send a signal to the second control device 200 indicating that the connection(s) have been performed. Based on the signal from the at least one sensor device 60, the second control device 200 may send a verification signal to the first control device 100 for verification of the connection(s). The first control device 100 may then generate a unique vehicle identity or registration number for the assembled vehicle 1. A vehicle 1 is thus assembled and the vehicle 1 is ready to perform the mission. The generated unique vehicle identity may then be stored in a database or record associated with the offboard-system, i.e. the control device 100. The generated unique vehicle identity may also be transmitted to the modules 30,40 of the vehicle 1. The unique vehicle identity may optionally be displayed by one or more of the modules 30, 40 of the vehicle 1.

Fig. 2a - Fig. 2c schematically illustrate a drive module 30 in a side view, a front view and in a view from above, according to an embodiment. The drive module 30 comprises a body 38. The wheels 37 are arranged on two opposite sides of the drive module 30. The body 38 may have a first and a second side 31, 32, which are facing in opposite directions. The body 38 may have a third and a fourth side 33, 34, which are facing in opposite directions, wherein the third side 33 and the fourth side 34 may extend perpendicular to the first and the second sides 31, 32. The body 38 may also have a fifth and a sixth side 35, 36, which are facing in opposite directions. The fifth and the sixth sides 35, 36 may extend perpendicularly to the first and the second sides 31, 32 and the third and fourth sides 33, 34. The first and the second sides 31, 32 may be referred to as side surfaces. The third and the fourth sides 33, 34 may be referred to as front and rear surfaces respectively. The fifth side 35 may be referred to as a top surface and the sixth side 36 may be referred to as a bottom surface. The sides 31, 32, 33, 34, 35, 36 may each have a shape that is flat or curved and may be shaped with indentations and protrusions. Instead of the perpendicularly extension of the sides 31, 32, 33, 34, 35, 36 described above, the sides 31, 32, 33, 34, 35, 36 may extend at any angle in relation to each other.

Fig. 3 schematically illustrates a drive module 30 in further detail in a side view. The drive module 30 comprises at least one (only one illustrated) propulsion system 91, an energy storage device 70, an interface 50 and a control device, i.e. a second control device 200.

The propulsion system(s) 91 comprises for example an electric machine(s) connected to the wheels 37. In some embodiments, each wheel 37 is individually driven by its own electric machine. The electric machine(s) may also work as generators and generate electric energy when braking the wheels 37. Thus, the propulsion system is typically the primary braking system of the vehicle 1.

However, because the braking functionality system may in some situations be insufficient or fail for some reason, a secondary braking system is required. This secondary braking system is herein referred to as the braking system. The braking system comprises for example standard disc brakes and electromechanical actuators that require reliable power supply.

The drive module 30 also comprises at least one energy storage device 70 for providing the propulsion system 91 with energy. The energy storage device 70 is for example an electric battery pack that may be recharged with electric energy.

In some embodiments, one or more of the drive modules 30 comprise a plurality of energy storage devices 70. For example, one drive module 30 may comprise several battery packs. Some of those energy storage devices may be arranged externally to the drive modules 30. For example, one or more energy storages 70 may be stacked on top of the drive module 30 and connected to the drive module 30 e.g. via an interface.

The second control device 200 is configured to operate the drive module 30 as an independently driven unit. The drive module 30 may transport itself without any externally driven unit such as a towing vehicle. The drive module 30 may transport itself by means of the at least one propulsion system 91. The drive module 30 may be configured to be autonomously operated. Thus, the second control device 200 may be configured to control the operation of the drive module 30. The second control device 200 may be configured to transmit control signals to the various systems and components of the drive module 30 for controlling for example the steering and the propulsion of the drive module 30. The second control device 200 may be configured to operate the drive module 30 autonomously based on received commands. The second control device 200 may thus be configured to receive commands from a remotely located off-board system i.e. the first control device 100, and to convert the commands into control signals for controlling the various systems and components of the drive module 30. The second control device 200 may also be configured to receive data about the surroundings from at least one sensor (not shown) and based on this data control the drive module 30. The second control device 200 will be described in further detail in connection with Fig. 5.

The drive module 30 may be configured to be releasably connected to either a second drive module 30 and/or a functional module 40 for forming an assembled vehicle 1. At least one of the sides 31, 32, 33, 34, 35, 36 of the drive module 30 may thus have a shape that allows the drive module 30 to be releasably connected to the second drive module 30 and/or the functional module 40.

The at least one interface 50 of the drive module 30 is configured to physically connect the drive module 30 with a second drive module 30 and/or a functional module 40. The interface(s) 50 of the drive module 30 may be releasably connectable to a corresponding interface 50 of a second drive module 30 and/or a functional module 40.

In Fig. 1 the drive modules 30 are illustrated with only one interface 50, on one side of the drive module 30. However, it is to be understood that each drive module 30 may comprise a plurality of interfaces 50 for releasable connection with other modules 30, 40. The interface(s) 50 of the drive modules 30 may be arranged on different sides of the drive module 30 and thus enable connection with other modules 30, 40 on multiple sides of the drive module 30. The interfaces 50 on the drive modules 30 and the functional modules 40 respectively, are suitably arranged on corresponding positions to enable connection between the modules 30, 40.

In some embodiments, the at least two interfaces 50 comprises electric interfaces, arranged for transferring electric power and/or transmitting electric signals between the drive module 30 and another module e.g. to a functional module 40 to which the drive module is connected. The electrical interface 50 may be a wired interface 50 or a wireless interface e.g. a conductive interface. In other words, by connecting the drive module 30 and the functional module 40 electrically, the modules 30, 40 may transfer power between each other and share information.

In some embodiments, the second control device 200 of the drive module 30 is configured to communicate with a further control device e.g. a control device 300 of a functional module 40. A functional module 40 may thus comprise a control device, which is referred to as a third control device 300. The drive module 30 may, for example, control parts of the functional module 40, such as opening and closing of doors, heating and cooling.

The communication between the modules 30, 40 may be wireless e.g. conductively or by wire. In some embodiment, electric power and/or electric signals is transmitted via one module further to a further module. In other words, one drive module 30 of the modular vehicle 1 may transmit electric power and/or electric signals via a functional module 40 and further to another drive module of the same vehicle 1, as illustrated by the connection 51 in Fig. 1. Thus, the connection 51 comprises e.g. at least one of a cable, bus or electrical line.

In some embodiments, the second control device 200 of the drive module 30 is configured to communicate directly with another drive module 30 or functional module 40 (or more specifically with a control device 200, 300 of the other drive module 30 or functional module 40) being a part of the same assembled vehicle 1 using e.g. a wireless communication protocol, which is illustrated by dashed lines in Fig. 1. The wireless communication may alternatively be performed via the offboard system (i.e. first control device 100). In case of wireless communication between the control devices 200, 300 of the modules 30, 40, each module (e.g. corresponding control device) comprises a communication interface including a transmitter and a receiver for the wireless communication. The modules 30, 40 of an assembled vehicle may communicate with each other and/or the first control device via 4G, 5G, V2V (Vehicle to Vehicle), Wi-Fi or any other wireless communication protocol.

In some embodiments, the drive module 30 is associated with a unique identity or registration number. The drive module 30 may thereby be regarded an independent vehicle. In the case where an assembled vehicle 1 comprises two drive modules, each drive module is associated with a distinct registration number. The first control device 100 may determine which of the drive modules 30 should show (or announce) its registration number. In some embodiments the registration number of the drive module 30 will become the registration number of the vehicle 1 (see above).

If the assembled vehicle 1 comprises two drive modules, the first control device 100 may appoint one drive module to be master drive module and the other to be slave drive module. Typically, the master drive module will be commanded to announce its registration number and the slave drive module will not show its registration number. The first control device 100 may thus transmit instructions regarding the registration number of the master drive modules to the second control devices 200 one or more of the of the other drive modules 30 in the set of modules 20.

In some embodiments, the first control device 100 is configured to determine a configuration and operations for an assembled vehicle 1 based on mission (or function) to be performed by the assembled vehicle 1, and to transmit the determined configuration to a second control device 200 being appointed to be a master drive module. The master drive module will then control the operation of the vehicle 1 while performing the mission.

The proposed technique will now be explained with reference to the flow chart of Fig. 4. As described above, this disclosure proposes a method for controlling energy levels of energy storage devices in a vehicle comprising a plurality of drive modules, such as the vehicle 1 illustrated in Fig.1 to Fig. 3. Flowever, even though reference is herein made to the vehicle 1 illustrated in Fig.1 to Fig. 3, it must be appreciated that the proposed method may be used for controlling any vehicle comprising a plurality of drive modules, wherein each drive module of the vehicle comprises an individual propulsion system operable to propel the vehicle and a chargeable energy storage device arranged to supply energy to the propulsion system.

The method may be implemented as a computer program comprising instructions which, when the program is executed by a computer (e.g. a processor 210 of a second control device 200 (Fig. 5)), cause the computer to carry out the method. According to some embodiments, the computer program is stored in a computerreadable medium (e.g. a memory or a compact disc) that comprises instructions which, when executed by a computer, cause the computer to carry out the method.

The proposed method is e.g. performed by a second control device 200 of a drive module 30 assigned to be a master drive module. However, it must be appreciated that the method may alternatively, at least partly, be implemented in the first control device 100 or in any one of the control devices 200, 300 of the modules of the vehicle, or the implementation may be distributed among any or all of the control devices 100, 200, 300 that jointly perform the method.

The proposed method comprises determining S1 energy levels of the chargeable energy storage devices 70 of the plurality of drive modules 30. An energy level may also be referred to as a charging level or power level. The energy level corresponds to an amount of energy currently stored in one of the energy storage devices 70. The energy level could be represented by an absolute value in e.g. kWh. Alternatively, the energy level may be represented by a relative value such as a fraction of a total energy level that can be stored in an energy storage device 70, where e.g. 100% corresponds to a fully loaded energy storage device and 0% to an empty energy storage device 70.

An energy level of each drive module 30 may be measured e.g. by measuring a voltage between the energy storage device’s terminals or by using an amperehour meter that keeps track of all power flowing in or out of the energy storage devices 70 over time. The determining S1 then implies obtaining or receiving all those measurements from the respective drive modules 30. For example, the master drive module receives information from the slave drive modules about their individual energy levels. The information may be received via the interface 50 or via wireless communication between the second control devices 200 of the master drive module and the slave drive module(s). If one drive module 30 comprises more than one energy storage device 70, then the total amount of energy stored in the energy storage devices 70 may be determined for that drive module 30. In principle, they could be treated as one single energy storage device 70.

The method further comprises controlling S2 operation of the individual drive modules 30, while operating the vehicle 1, based on the determined energy levels. In other words, when performing a mission, the requested propulsion torque, or generated energy that may be used for charging the energy storage devices 70, is distributed among the drive modules 30 based on how much energy is previously stored in the respective drive modules 30 (or more specifically in their respective energy storage devices 70). For example, the second control device 200 of the master drive module sends control data to the second control devices 200 of a plurality of slave drive modules to control their operation. The control data may be sent via the interface 50 or via wireless communication between the second control devices 200 of the master drive module and the slave drive module.

To avoid the problem that one individual drive module 30 of a modular vehicle 1 runs out of power it is typically desirable that the stored power of the individual drive modules 30 (or rather of their energy storage devices 70) are kept at about the same level or within a certain interval. Stated differently, in some embodiments, the controlling S2 comprises controlling operation of the drive modules 30 to balance the individual energy levels of the chargeable energy storage devices 70 among the drive modules 30. If the charging levels are already about the same level, then the controlling simply implies evenly distributing requested propulsion torque and charging such that the levels are maintained.

However, the chargeable energy storage devices 70 of the drive modules 30 may for different reasons have individually different energy levels. This may e.g. depend on their age, when they were charged, or on the mission they were previously participating in.

There are different ways of controlling S2 the operation of the vehicle 1 and at the same time controlling the energy levels of the individual energy storage devices 70 of the vehicle 1. For example, the distribution of energy outtake for propelling the vehicle 1 may be controlled, such that mainly one or some of the drive modules 30 are used to propel the vehicle 1, and that the other drive modules are not used or at least used to a lesser degree . In other words, in some embodiments, the controlling S2 operation of an individual drive module 30 comprises controlling the propulsion system 30 of the drive module 30 to propel the vehicle 1, whereby the energy level of the corresponding energy storage device 70 is decreased.

This typically means that the power outtake is controlled such that (if possible) a drive module 30 comprising a “sufficient” amount of energy, or even the drive module 30 comprising the most energy, is used to propel the vehicle 1. A sufficient amount corresponds e.g. to an amount enough to perform an assigned mission. Stated differently, in some embodiments, the controlling S2 comprises propelling the vehicle 1 using one or more of the drive modules 30 having the highest energy levels among the drive modules 30. Note that the control of the propelling is typically based also on other criteria that may affect driving behavior, security etc. These criteria may in some scenarios be in conflict. For example, a certain drive module with a low amount of stored energy is required to obtain a certain driving behavior due to other properties such as power, gearing etc.

Another possibility is to avoid using drive modules 30 comprising a very low amount of stored energy for propelling the vehicle 1. This may be accomplished by simply deactivating the propulsion systems 91 of these drive modules 30, and simply let their wheels roll freely (e.g. by declutching the wheels). In other words, in some embodiments the controlling S2 of operation of an individual drive module 30 may alternatively comprise controlling the propulsion system 30 of the drive module 30 to be deactivated.

For example, there may be a lower limit (for the energy level) that one should (if possible) never go below. The lower limit may e.g. correspond to an energy level needed to keep the drive module “alive” or to drive the drive module 30 a shorter distance without a load. In other words, in some embodiments, the controlling S2 comprises distributing energy outtake among the energy storage devices 70 drive modules 30 such that their individual energy levels do not go below a predetermined minimum energy level.

As mentioned above, the propulsion systems may in some scenarios be reconfigured to operate as generators, e.g. in a downhill. The propulsion systems may then generate energy that can be used to charge the energy storage devices 70 of the drive modules 30. In other words, in some embodiments, the controlling S2 operation of an individual drive module 30 comprises controlling the propulsion system 30 of the drive module 30 to operate as a generator, whereby the energy level of the corresponding energy storage device 70 is increased. Thus, energy generated e.g. in a downhill or when braking the vehicle 1 may be used to charge the energy storage devices 70 having low (or the lowest) amount of stored energy. This may be used, if one or more drive module 30 have a level approaching the lower limit. In other words, in some embodiments, the chargeable energy storage devices 70 of the drive modules 30 have individually different energy levels and the controlling S2 comprises operating one or more of the drive modules 30 having the lowest energy levels among the drive modules 30 as generators, to charge their corresponding energy storage devices 70.

A “low” energy level and a “high” energy level may be defined in different ways. For example, thresholds (in kWh) may be used to group the driving modules in different groups based on energy levels, e.g. high level, medium (or sufficient) level and low level. Another possibility is to use a relative grouping, where the 50 percent of the drive modules that have the highest energy levels are considered as “high level” and the other as “low level”.

In some situations, it might be enough to use the propulsion and braking functionality to distribute the stored energy between the energy storage devices 70. However, in some cases it may not be possible, e.g. when four-wheel drive is required for a mission. Hence, it may be required that energy is transferred between the energy storage devices 70 of different drive modules. One way of doing this is to transfer energy directly between the modules over the interface 50 by electrically connecting energy storage device 70 of different drive modules 30 via their interfaces 50.

However, if two energy storage devices 70 have completely different energy levels, a direct connection of the energy storage devices 70 may be inappropriate, as such a connection might cause a rush of current between the energy storage devices 70. A current rush is a potential risk as it may cause sparking and negatively influence the life-time of the energy storage devices 70. However, once the energy levels of the energy storage devices 70 are about the same, such a connection may be used to maintain the energy levels.

Another way of transferring energy between the energy storage devices 70 is to reconfigure the propulsion systems 91 of the drive modules 30 having a low energy level to work as generators in order to charge their energy storage devices 70 while propelling the vehicle 1. The generators are driven by the drive module's wheels 37. The drive modules whose energy storage devices 70 have high (or medium) energy levels, are then used to propel the vehicle 1. This basically means that energy is mechanically transferred via the wheels 37. In other words, in some embodiments the controlling S2 comprises transferring energy between energy storage devices 70 of the different drive modules 30 by operating at least one of the drive modules 30 as a generator while propelling the vehicle 1 using at least one of the other drive modules 30. In other words, at least one drive module 30 brakes the vehicle 1 at the same time as another drive module 30 propels the vehicle 1. “At the same time” does not have to be exactly simultaneously, as long as the momentum created by the propelling drive module 30 can be utilized by the other drive module 30 to generate energy.

One might want to avoid doing this too often as there is a risk of energy loss due to friction. However, if one drive module 30 is otherwise risking to “die” due to the energy level going below the lower limit mentioned below, this might be preferable. In other words, in some embodiments the transferring is triggered by one or more of the energy storage devices 70 of a drive module 30 having an energy level below a predetermined threshold.

In some embodiment, the transferring is only used during a limited amount of time until the energy levels are equalized, e.g. in an initial phase after assembling the vehicle 1. For example, until the difference between the highest and the lowest energy level, or the standard deviation of the energy levels, meets a threshold value. The even distribution may then be maintained by evenly distribution requested torque and charging or simply by connecting the energy storage devices 70 upon achieving an even distribution.

The proposed technique is applicable on all sorts of road vehicles. However, the disclosure may relate to heavy vehicles, such as buses, trucks etc. Specifically, the present disclosure may relate to vehicles for use on public roads.

Now turning to Fig. 5 which illustrates an example implementation a control device configured to implement the proposed method. The second control device 200 is for use in a vehicle 1 comprising a plurality of drive modules 30, wherein each drive module 30 comprises an individual propulsion system 91 operable to propel the vehicle and a chargeable energy storage device 70 arranged to supply energy to the propulsion system 91. In this example the control device is embodied as a second control device 200 of a drive module 30 assigned to be a master drive module 30 of the vehicle 1.

In some embodiments, the second control device 200 is a “unit” in a functional sense. Hence, in some embodiments the second control device 200 is a control arrangement comprising several physical control devices that operate in corporation. The second control device 200 comprises hardware and software. The hardware basically comprises various electronic components on a Printed Circuit Board, PCB. The most important of those components is typically a processor 210 along with a memory 220.

The second control device 200 also comprises one or more communication interfaces 230, enabling the second control device 200 to communicate with other modules 30, 40 of the modular vehicle 1, or of other vehicles. The communication between the modules is as mentioned above wireless, conductive or wired. Wired communication may be implemented standard protocols such as Controller Area Network, CAN. CAN is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other in applications without a host computer. Wireless communication between the modules may be implemented using any short-range communication protocol such as Bluetooth or 802.11.

In some embodiments, the one or more communication interfaces 230 also comprises a wireless communication interface. The wireless communication interface e.g. enables the second control device 200 to communicate with the first control device 100, i.e. with the off-board system. The wireless communication interface is e.g. implemented using 4G, 5G, V2V (Vehicle to Vehicle) or any other suitable wireless communication protocol. The first control device 100, the second control device 200 and the third control device 300 may then communicate on a higher level using e.g. Internet Protocol, IP.

The second control device 200, or more specifically the processor 210 of the second control device 200, is configured to cause the second control device 200 to perform all aspects of the method described above and below. This is typically done by running computer program code stored in the memory 220 in the processor 210 of the second control device 200.

More particularly, the second control device 200 is configured to determine energy levels of the chargeable energy storage devices 70 of the plurality of drive modules 30 and to control transfer of energy between the chargeable energy storage devices 70 and the propulsion systems 91 of the drive modules 30 based on the determined energy levels.

In some embodiments, this disclosure relates to a vehicle 1 comprising a plurality of drive modules 30, wherein each drive module 30 comprises a propulsion system 91 and a chargeable energy storage device 70 arranged to supply energy to the propulsion system 91. The vehicle 1 further comprises at least one control device 200, 300 configured to (at least partly) perform any or all of the aspects of the method illustrated in Fig. 4.

The terminology used in the description of the embodiments as illustrated in the accompanying drawings is not intended to be limiting of the described method; control arrangement or computer program. Various changes, substitutions and/or alterations may be made, without departing from invention embodiments as defined by the appended claims.

The term “or” as used herein, is to be interpreted as a mathematical OR, i.e., as an inclusive disjunction; not as a mathematical exclusive OR (XOR), unless expressly stated otherwise. In addition, the singular forms "a", "an" and "the" are to be interpreted as “at least one”, thus also possibly comprising a plurality of entities of the same kind, unless expressly stated otherwise. It will be further understood that the terms "includes", "comprises", "including" and/ or "comprising", specifies the presence of stated features, actions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, actions, integers, steps, operations, elements, components, and/ or groups thereof. A single unit such as e.g. a processor may fulfil the functions of several items recited in the claims.

Claims

1. A method for controlling energy levels of energy storage devices (70) in a vehicle (1) comprising a plurality of drive modules (30) configured to be operated as independently driven units, wherein each drive module (30) comprises an individual propulsion system (91) operable to propel the vehicle (1) and a chargeable energy storage device (70) arranged to supply energy to the propulsion system (91), the method comprising: - determining (S1) energy levels of the chargeable energy storage devices (70) of the plurality of drive modules (30), and - controlling (S2) operation of the propulsion systems (91) of the individual drive modules (30), while operating the vehicle (1), based on the determined energy levels.

2. The method according to claim 1, wherein the controlling (S2) of operation of an individual drive module (30) comprises at least one of: - controlling the propulsion system (30) of the drive module (30) to propel the vehicle (1), whereby the energy level of the corresponding energy storage device (70) is decreased, - controlling the propulsion system (30) of the drive module (30) to operate as a generator, whereby the energy level of the corresponding energy storage device (70) is increased, and/or - controlling the propulsion system (30) of the drive module (30) to be deactivated.

3. The method according to claim 1 or 2, wherein the controlling (S2) comprises controlling operation of the drive modules (30) to balance the individual energy levels of the chargeable energy storage devices (70) among the drive modules (30).

4. The method according to any of the preceding claims, wherein the controlling (S2) comprises distributing energy outtake among the energy storage devices (70) drive modules (30) such that their individual energy levels do not go below a predetermined minimum energy level.

5. The method according to any of the preceding claims, wherein the chargeable energy storage devices (70) of the drive modules (30) have individually different energy levels and wherein the controlling (S2) comprises propelling the vehicle (1) using one or more of the drive modules (30) having the highest energy levels among the drive modules (30).

6. The method according to any of the preceding claims, wherein the chargeable energy storage devices (70) of the drive modules (30) have individually different energy levels and wherein the controlling (S2) comprises operating one or more of the drive modules (30) having the lowest energy levels among the drive modules (30) as generators, to charge their corresponding energy storage devices (70).

7. The method according to any of the preceding claims, wherein the controlling (S2) comprises transferring energy between energy storage devices (70) of the different drive modules (30) by operating at least one of the drive modules (30) as a generator while propelling the vehicle (1) using at least one of the other drive modules (30).

8. The method of claim 7, wherein the transferring is triggered by one or more of the energy storage devices of a drive module (30) having an energy level below a predetermined threshold.

9. A computer program comprising instructions which, when the program is executed by a control device, cause the control device to carry out the method of any one of the claims 1 to 8.

10. A computer-readable storage medium comprising instructions which, when executed by a control device, cause the control device to carry out the method of any one of the claims 1 to 8.

11.A control device (200) for use in a vehicle (1) comprising a plurality of drive modules (30) configured to be operated as independently driven units, wherein each drive module (30) comprises an individual propulsion system (91) operable to propel the vehicle (1) and a chargeable energy storage device (70) arranged to supply energy to the propulsion system (91), the control device (200) being configured to: - determine energy levels of the chargeable energy storage devices (70) of the plurality of drive modules (30), and - controlling (S2) operation of the propulsion systems (91) of the individual drive modules (30), while operating the vehicle (1), based on the determined energy levels.

12. The control device of claim 11, wherein the control device is configured to perform the method according to any one of claims 2-10.

13. The control device of claim 11 or 12, wherein the control device is comprised in one of the drive modules (30) which is assigned to be a master drive module of the vehicle (1) and wherein the other drive modules (30) are slave drive modules.

14. A vehicle (1) comprising: - a plurality of drive modules (30), wherein each drive module (30) comprises a propulsion system (91) and a chargeable energy storage device (70) arranged to supply energy to the propulsion system (91), - the control device (200) according to claim 11 or 13.