WO2020104013A1

WO2020104013A1 - A battery system for a vehicle

Info

Publication number: WO2020104013A1
Application number: PCT/EP2018/081853
Authority: WO
Inventors: Istaq AHMED
Original assignee: Volvo Truck Corp
Current assignee: Volvo Truck Corp
Priority date: 2018-11-20
Filing date: 2018-11-20
Publication date: 2020-05-28
Anticipated expiration: 2021-05-20
Also published as: WO2020104508A1; EP3883810A1

Abstract

The disclosure relates to a battery system for a vehicle comprising a first electric conductor, a second electric conductor and a first battery unit arranged therebetween to form a first electrical circuit for transferring of electrical energy, wherein the battery system further comprises a first controllable electromechanical contactor arranged between the first battery unit and the first electrical conductor, and operable to control an electrical connection between the first battery unit and the first electric conductor.

Description

A battery system for a vehicle

TECHNICAL FIELD

The disclosure relates to a battery system for a vehicle. Moreover, the disclosure relates to a vehicle comprising such a battery system. Also, the disclosure relates to a method for controlling a battery system in a vehicle.

The disclosure can be applied in any type of hybrid vehicles or electrical vehicles, such as partly or fully electrical vehicles. Although the disclosure will be described with respect to an electrical truck, the disclosure is not restricted to this particular vehicle, but may also be used in other hybrid or electrical vehicles such as electrical buses, electrical construction equipment, electric ferries and marine vehicles, and electrical cars. The disclosure may also be applied in any other type of electrical vehicle such as electrical powered construction equipment, electrical working machines e.g. wheel loaders, articulated haulers, dump trucks, excavators and backhoe loaders, electric genset or stationary battery power sources etc.

BACKGROUND

Batteries are becoming a common source of power for providing propulsion for vehicles. Such batteries are often rechargeable batteries and typically include a number of battery stacks having a number of battery cells that may be connected in series or in parallel forming a complete battery system for the vehicle. The quality of the battery system is partly dependent on the quality of each battery cell, thereby setting strict requirements on the production quality of the battery cells. As a consequence, battery systems for partly electric and fully electric vehicles are regarded as critical parts of the vehicle that are made up of rather technically advanced components, thus often being relatively expensive components of the vehicle.

In addition, these types of battery systems must be arranged and operated to optimize performance and safety during charging and discharging. However, battery modules and battery cells may nevertheless have somewhat different capacities despite the high quality and may also age differently due to e.g. differences in quality and chemistry. Eventually, this will lead to unbalanced battery cells in terms of e.g. state of charge (SOC) and/or available capacity. It may also happen that individual battery cells of the battery system become over discharged and even permanently damaged. Other problems with battery cells may also occur during charging and discharging, e.g. abnormal heating, gas formation or dendrite formation which may cause internal short circuits etc.

In order to manage possible faulty battery cells in a battery system, some systems may have a battery cell bypass arrangement. By way of example, US 2012 091 964 A1 describes a battery by-pass circuit using a controller to sense when a battery cell is damaged. In response to a performance loss, the controller is arranged to activate a switching element in order to activate the battery cell bypass circuit. Despite the activity in the field of battery systems, there remains a need for an improved control of possible faulty battery modules and/or battery cells of a battery system of a vehicle, such as a partly or fully electrical vehicle.

SUMMARY

An object of the disclosure is to provide an improved arrangement for disconnecting one or more battery units, e.g. battery cells, of a battery system of a vehicle. The object is at least partly achieved by a system according to claim 1.

According to a first aspect of the disclosure, there is provided a battery system for a vehicle comprising a first electric conductor, a second electric conductor and a first battery unit arranged therebetween to form a first electrical circuit for transferring of electrical energy. Moreover, the battery system comprises a first controllable electromechanical contactor arranged between the first battery unit and the first electric conductor. The electromechanical contactor is operable to control an electrical connection between the first battery unit and the first electric conductor.

By the arrangement of the example embodiments of the disclosure, it becomes possible to control connection and disconnection of the battery unit from the first electric conductor in a more flexible and efficient manner. By way of example, it becomes possible to isolate the first battery unit from other battery units of the battery system. To this end, there is provided an improved battery system in which a problematic battery unit, such as a faulty battery cell, can be disconnected from the other battery cells of the battery system. In this context, it is to be noted that a battery system of a hybrid vehicle or electric vehicle may comprise about 100 series-connected battery cells or more in order to store and deliver a sufficient level of energy. If one weak battery cell prematurely runs out of charge cycles due to overcharging or excessive discharging, the entire battery system of series- connected cells may need to be repaired or replaced. Problems in a battery cell may also occur due to abnormal heating, gas formation or dendrite formation which may cause internal short circuits etc. As a consequence, heat transfer/propagation via conventional bus bars can be limited during the thermal runaway occurrence. The example

embodiments of the system are particularly useful during ordinary operation of a vehicle having an electrical propulsion system. By way of example, the system according to the example embodiments can be used as an integrated part of an electrical propulsion system of a vehicle. Thus, the example embodiments can be used on-board (or on-line) of the vehicle and typically during operation of the vehicle.

In other words, the battery unit(s) of the battery system is connected to the first electrical conductor by a versatile and operable electromechanical contactor rather than being connected directly to a bus bar.

In addition, the provision of having an electromechanical contactor operable to control an electrical connection between the electrical conductor and the battery unit, the example embodiments allows not only for an immediate and efficient control of the battery unit(s) of the battery system, but also for a remote control of the battery units of the battery system. By using a remote control of the battery unit, the vehicle can be stopped remotely from any misuse or undesirable operations.

By arranging an electromechanical contactor between the electrical conductor and the battery unit, it becomes possible to control the electrically conductive relationship between the battery unit and the electric conductor.

To this end, a battery unit can be disconnected from the electrical conductor, and thus isolated, i.e. set in a state where no electrical energy is transferable through the battery unit, by controlling the electromechanical contactor. Hereby, the battery unit is

disconnected or isolated during e.g. charging or discharging. In this manner, no current is fed through the disconnected or isolated battery unit during discharging or charging of the battery system. The disconnected or isolated battery unit may be connected again by controlling the electromechanical contactor. In other words, resuming discharging or charging of the battery unit is performed by connecting the battery unit to the electrical conductor by controlling the electromechanical contactor. By way of example, the battery unit is re-connected to the electrical conductor by actuating the electromechanical contactor to establish the electrical connection between the battery unit and the electrical conductor. Typically, although not strictly required, all battery units of the battery system are arranged according to the above example embodiment relating to the first battery unit and the first controllable electromechanical contactor arranged between the first battery unit and the first electrical conductors. As used herein, the term“electric conductor” typically refers to a conductor configured to transfer electrical energy. One example of an electrical conductor is a bus bar, e.g. a main rail bus bar. A bus bar is a well-known component of a battery system.

The electromechanical contactor can be provided in several different manners. The term “electromechanical contactor” as used herein typically refers to an electromechanical device operable to turn on and off an electric current in an electrical connection. In other words, the electromechanical device is operable to open and close the electrical connection between a battery unit and an electrical conductor of the battery system. The electromechanical contactor should be configured for repeatedly establishing and interrupting electric power circuits. In the electromechanical contactor, the force for the closing and opening of the main contacts is provided by an electromagnet. In other words, the electromechanical contactor is generally a contactor that is caused to operate by an electromagnet. The electromechanical contactor is typically actuated by a circuit. That is, the electromechanical contactor is generally controlled by a first circuit, which has a lower power level than the power transferable in the electrical connection to be controlled by the electromechanical contactor. In this context, the electrical connection typically

corresponds to a second circuit. Typically, the electromechanical contactor can be any one of a solenoid valve, relay, electric switch etc. These types of contactors are electromechanical devices that use an electromagnetic solenoid to actuate one or more pairs of contacts. A single pole relay or contactor typically has a single pair of contacts. However, it may also be conceivable to use double pole relays and contactors.

Contacts may be normally open or normally closed. Hence, the electromechanical contactor may be a normally open (NO) contactor, i.e. the contacts in the electrical connection (“second circuit”) are not connected by default, and switch on only when a current flows through the electromechanical contactor. Alternatively, the electromechanical contactor may be a normally closed (NC) contactor, i.e. the contacts in the electrical connection are connected so a current flows through them by default, and switch off only when the electromechanical contactor is energized (activated), thereby pulling or pushing the contacts apart. Some contactors may also have double throw contacts that combine a normally open and normally closed contact.

According to one example embodiment, the battery system further comprises a second controllable electromechanical contactor arranged between the first battery unit and the second electric conductor. Further, the second controllable electromechanical contactor is operable to control an electrical connection between the first battery unit and the second electric conductor. In this manner, the interruption of electrical current through the battery unit is performed in an even more secure manner as the electrical connection on both sides of the battery unit is broken. For example, if one of the battery units is aged or the operating conditions of the battery unit appear abnormal, the battery unit can be isolated from the other battery units’ connection and vehicle can be still operable using other battery units with limited performance. The second controllable electromechanical contactor is typically of a similar type of electromechanical contactor as the first controllable electromechanical contactor.

According to one example embodiment, the battery system comprises a plurality of battery units individually arranged in-between the first electric conductor and the second electric conductor to form a plurality of individual electrical circuits for transferring electrical energy. Also, the battery system typically comprises a plurality of additional electromechanical contactors arranged individually between each one of the plurality of battery units and the first electric conductor, respectively. Further, the plurality of additional electromechanical contactors is typically arranged individually between each one of the plurality of battery units and the second electric conductor, respectively. In this manner, it becomes possible to individually control a plurality of battery units of the battery system. Typically, although not strictly required, all battery units of the battery system are arranged according to the above example embodiment relating to the first battery unit and the first controllable electromechanical contactor arranged between the first battery unit and the first electrical conductors and the second controllable electromechanical contactors arranged between the first battery unit and the second electric conductor. In this manner, the example embodiment provides for disconnecting one or several of these battery cells by means of the electromechanical contactors, respectively, while permitting the other ones of the battery cells to continue to charge or discharge.

Generally, the battery system comprises a battery system control unit arranged in communication with the electromechanical contactor and configured to control actuation of the electromechanical contactor based on a control signal. The battery system control unit may sometimes also be denoted as a battery management unit or battery

management system. Typically, the battery system control unit is arranged in electrical communication with the electromechanical contactor and configured to control actuation of the electromechanical contactor based on a control signal.

By way of example, the actuation of the electromechanical contactor causes a closed circuit in the electrical connection. Typically, the actuation of the electromechanical contactor is controllable to form a closed circuit in the electrical connection when receiving a control signal from the battery systems control unit.

Alternatively, the actuation of the electromechanical contactor causes an open circuit in the electrical connection. Typically, the actuation of the electromechanical contactor is controllable to form an open circuit in the electrical connection when receiving a control signal from the battery systems control unit.

Further, the electromechanical contactor is generally configured to control energization of the electromechanical contactor based on the control signal. Energization of the electromechanical contactor may be provided e.g. by controlling an electric current or voltage through the electromechanical contactor. In addition, or alternatively, the electromechanical contactor may be configured to control de-energization of the electromechanical contactor based on a control signal. De-energization of the

electromechanical contactor may be provided e.g. by controlling an electric current or voltage through the contactor.

As will be further described herein, the control signal is typically indicative of a deviation in an operational property of the battery unit. In addition, or alternatively, the control signal may be indicative of a malfunction of the battery unit. According to one example embodiment, the battery system control unit is further configured to determine a deviation in an operational property of the battery unit. The term “operational property”, as used herein, may refer to any one of voltage, current or temperature. By way of example, the battery system control unit is configured to determine a deviation in voltage through the battery unit. That is, the battery system control unit is configured to determine a voltage drop. In addition, or alternatively, the battery system control unit is configured to determine a deviation in current through the battery unit. That is, the battery system control unit is configured to determine a decrease in current through the battery unit. In addition, or alternatively, the battery system control unit is configured to determine a deviation in temperature of he battery unit. That is, the battery system control unit is configured to determine an increase in the temperature of the battery unit. The deviation in the operational property of the battery unit may reflect a malfunction of the battery unit.

According to one example embodiment, the battery system control unit is configured to detect a malfunction of the battery unit, and the control signal indicates the malfunction of the battery unit. The malfunction of the battery unit may generally refer to a voltage drop or a temperature increase.

By way of example, the electromechanical contactor is configured to cause a break in the electrical connection between the battery unit and the first electric conductor in response to receiving the control signal. A break in the electrical connection thus refers to an interruption causing a disconnection of the battery unit from the first electrical conductor.

According to one example embodiment, the electromechanical contactor is configured to disconnect the battery unit from the first electrical conductor in response to the receiving the control signal.

According to one example embodiment, the battery system further comprises a sensor device arranged in proximity to the battery unit and configured to detect a hazardous operational condition of the battery unit. The term“hazardous operational condition”, as used herein, may refer to any one of smoke, fire, vents open (thereby gas released from the battery), electrolyte spilling or any other activity that may be detrimental to the battery cell and the battery system. The sensor device is arranged to monitor the battery unit. If the battery unit is a battery cell, the sensor device is arranged to monitor the battery cell. In addition, or alternatively, the sensor device is typically arranged to monitor a plurality of battery units (battery cells) of the battery system. Accordingly, in one example embodiment, the sensor device comprises a number of sensor unit arranged to monitor a number of battery units (battery cells), respectively. The sensor device is typically arranged inside the battery system and in proximity to the battery units, such as the battery cell(s). Alternatively, the sensor device is arranged outside the battery system, while arranged to monitor the battery system and any one of the battery cells. Accordingly, the sensor device can be arranged in several different manners as long as the sensor device is capable of detecting a hazardous operational condition of the battery unit. It is also conceivable that the system may comprise a combination of an inside sensor device and an outside sensor device according to any one of the examples mentioned above.

By way of example, the sensor device is any one of a video device, e.g. a wireless video device, a smoke detector, a fire detector, a gas sensor, a flame sensor and a liquid sensor. Thus, according to one example embodiment, the sensor device is a wireless video device. According to one example embodiment, the sensor device is a smoke detector. According to one example embodiment, the sensor device is a fire detector. According to one example embodiment, the sensor device is a gas sensor. According to one example embodiment, the sensor device is a flame sensor. According to one example embodiment, the sensor device is a liquid sensor.

As mentioned above, the battery system typically comprises the battery system control unit, sometimes also denoted simply as the battery control unit, control unit or the battery management system. By way of example, the battery system control unit is an electronic control unit comprised on-board the vehicle. The battery system control unit may also be a cloud server arranged in networked communication with the vehicle. In addition, or alternatively, the battery system control unit may be implemented using a cloud server being network connected to the electronic control unit (ECU) comprised with the vehicle

According to one example embodiment, the battery system control unit further comprises a user communication device in networked communication with the battery system control unit. In one example embodiment, the user communication device is a so called remote communication device, sometimes also denoted as a remote control unit. According to one example embodiment, the user communication device is configured to communicate with the electromechanical contactor. In addition, the user communication device may comprise a remote monitoring unit in communication with one or several sensor devices of the example embodiments as mentioned above. In one example embodiment, the user communication device is arranged to communicate with the battery system control unit, any one of the electromechanical contactors and any one of the sensor devices. In some example embodiments, the user communication device is arranged to communicate with the battery system control unit, only. In some example embodiments, the user communication device is arranged to communicate with any one of the electromechanical contactors, only. In some example embodiments, the user communication device is arranged to communicate with any one of the electromechanical contactors and any one of the sensor devices, only. According to one example embodiment, the user communication device can be operable to interrupt all electrical connections of the battery system by controlling the

electromechanical contactors. In this manner, it becomes possible to completely disconnect the battery system from the other electrical components of the vehicle by means of the user communication device.

Typically, the user communication device is arranged to communicate with the battery system control unit by means of a cellular communication network. By way of example, the user communication device is arranged to communicate with the battery system control unit by a cellular communication network of the vehicle. However, the user communication device may communicate with the battery system control in several different manners. Such a communication between the user communication device and the battery system control unit may comprise circuits for conducting any wireless or wire bound communication, including, a vehicle (local) area network (LAN) connection, a wireless vehicle (local) area network (WLAN, WiMAX, WiFi) connection, a GSM/GPRS connection, a 3G/4G/LTE connection, a Bluetooth (TM) connection, and the like. In other words, in such embodiments a user signal in the user communication device is generated and forwarded via some kind of network to the battery system control unit that control the electrical contactor according to any one of the example embodiments above. As a consequence, the user signal in such embodiments may take the form of one or more protocol packets or messages. By way of example, the user communication device is a software implemented in a mobile device. In addition, or alternatively, the user communication device may be any one of a mobile device, tablet, pager, i.e. a portable device, which is carried by the user. The user communication device typically includes a software for communicating with the battery system control unit. The user communication device may also be provided in the form of an app or the like implemented in a mobile device

Also, the user communication device may be arranged in a dash board of the vehicle. The user communication device may also be a touch screen.

The user communication device may be a cloud server arranged in networked

communication with the battery system control unit. In addition, or alternatively, the user communication device may be implemented using a cloud server being network connected to the electronic control unit (ECU) comprised with the vehicle.

The battery system control unit may include a microprocessor, microcontroller,

programmable digital signal processor or another programmable device. Thus, the battery system control unit comprises electronic circuits and connections as well as processing circuitry such that the battery system control unit can communicate with the battery system. Typically, the battery system control unit may also be capable of communicating with different parts of the electrical propulsion system such as the electrical machines and other electrical components. Typically, the battery system control unit may also be configured to communicate with other parts of the vehicle such as the brakes, suspension, the clutch, transmission and further electrical auxiliary devices, e.g. the air conditioning system, in order to at least partly operate the vehicle. The battery system control unit may comprise modules in either hardware or software, or partially in hardware or software and communicate using known transmission buses such as CAN-bus and/or wireless communication capabilities. The processing circuitry may be a general purpose processor or a specific processor. The battery system control unit typically comprises a non- transistory memory for storing computer program code and data upon. Thus, the battery system control unit may be embodied by many different constructions.

In other words, the control functionality of the example embodiments of the battery system may be implemented using existing computer processors, or by a special purpose computer processor for an appropriate system, incorporated for this or another purpose, or by a hardwire system. Embodiments within the scope of the present disclosure include program products comprising machine-readable medium for carrying or having machine- executable instructions or data structures stored thereon. Such machine-readable media can be any available media that can be accessed by a general purpose or special purpose computer or other machine with a processor. By way of example, such machine- readable media can comprise RAM, ROM, EPROM, EEPROM, CD-ROM or other optical disk storage, magnetic disk storage or other magnetic storage devices, or any other medium which can be used to carry or store desired program code in the form of machine-executable instructions or data structures and which can be accessed by a general purpose or special purpose computer or other machine with a processor. When information is transferred or provided over a network or another communications connection (either hardwired, wireless, or a combination of hardwired or wireless) to a machine, the machine properly views the connection as a machine-readable medium. Thus, any such connection is properly termed a machine-readable medium. Combinations of the above are also included within the scope of machine-readable media. Machine- executable instructions include, for example, instructions and data which cause a general purpose computer, special purpose computer, or special purpose processing machines to perform a certain function or group of functions. While the example embodiments of the battery system described above includes a battery system control unit being an integral part thereof, it is also possible that the control unit may be a separate part of the vehicle, and/or arranged remote from the battery system and in communication with the battery system.

The battery system control unit may also include a model of one battery system. Thus, the battery system typically includes the battery system control unit configured to control the functionality of the battery system by means of the model of the battery system.

In the context of the example embodiments, the term“battery unit” may refer to a battery module comprising a number of series connected battery cells. Typically, a battery system comprises a set of battery modules connected in parallel, each one of the battery modules having a set of battery cells connected in series In addition, or alternatively, the term “battery unit” may refer to an individual battery cell.

As mentioned above, the battery system typically has a multiple number of individual battery modules connected in parallel to form the battery system. A battery module may be a battery cell string comprising a number of serially interconnected single battery cells. A battery module may sometimes also be denoted as a battery pack. That is, the battery cells are connected in series in the battery cell modules, while the battery cell modules are connected in parallel in the battery system. By way of example, any one of the battery cells in the battery system is any one of a lithium-ion battery or sodium-ion battery. A sodium-ion battery typically includes any type of sodium iron battery or sodium ferrite battery. It is to be noted, however, that the battery system can include different types of batteries. The battery system may comprise about 100 series-connected electrochemical cells, and preferably at least 150 series-connected cells, for example lithium cells.

Typically, the output voltage of the battery system equals the accumulated output voltage of each cell of a common battery module or battery string. A battery system may of course comprise two or more parallel-connected battery modules of series-connected battery cells, where each battery module comprises about 100 - 200 cells, for the purpose of increasing the total electrical capacity of the electrical storage system. The number of battery modules of a battery system may vary. By way of example, the number of battery modules is about 2 - 20, preferably about 4 - 15, more preferably about 5 - 10. In one example, the number of battery modules of the battery system is seven. Also, it is to be noted that the battery system is generally a so called high voltage battery system. In this context, the term“high voltage” refers to a battery system of about 400 - 1000 voltage (V).

The phrase“during use of the battery system” may refer to the state of charging of the battery system, and/or to the state of using (discharging) the battery system during operation of the vehicle, e.g. driving of the vehicle.

According to a second aspect of the present disclosure, there is provided a vehicle electrical propulsion system comprising an electric machine and a battery system according to any one of the example embodiments of the first aspect. The battery system is configured to provide electric power to the electric machine.

Effects and features of the second aspect of the disclosure are largely analogous to those described above in connection with the first aspect.

Generally, the term“electrical propulsion system”, as used herein, typically refers to vehicle electrical components for providing energy (such as traction energy) and for storing energy (delivering and receiving energy). The electrical propulsion system is in particular configured to deliver and receive energy for providing propulsion to the vehicle, but also for performing various vehicle operations of the vehicle. One component of the electrical propulsion system is the battery system.

The electrical propulsion system comprises an electrical machine such as an electrical motor for providing power to the vehicle. The battery system is connected to the electrical motor to provide power to the electrical motor. The electrical propulsion system can be incorporated and installed in a partly or fully electrical vehicle. The electrical motor can be provided in several different manners. According to one example embodiment, the electrical motor is any one of a permanent magnet synchronous machine, a brushless DC machine, an asynchronous machine, an electrically magnetized synchronous machine, a synchronous reluctance machine or a switched reluctance machine. Typically, the electrical motor is configured for driving at least a ground engaging member. Typically, the electric motor is configured for driving a pair of ground engaging members. By way of example, the ground engaging member is a wheel, a track or the like. The electrical motor can be coupled to the ground engaging members in several different manners. In one example embodiment, the electrical motor is coupled to a pair of ground engaging members by means of a transmission and a clutch. The transmission typically comprises a number of gears including a neutral gear.

According to a third aspect of the present disclosure, there is provided a vehicle, such as a fully or hybrid electrical vehicle, comprising a battery system according to any one of the example embodiments mentioned above in relation to the first aspect of the disclosure or a vehicle propulsion system according to any one of the example embodiments mentioned in relation to the second aspect of the disclosure.

Effects and features of the third aspect of the disclosure are largely analogous to those described above in connection with the first aspect and the second aspect. The vehicle may be an electrical, hybrid, or plug-in hybrid vehicle comprising an electrical motor, wherein the battery system provides power to the electrical machine for providing propulsion for the vehicle. It is to be noted that the vehicle can therefore be either a partly of fully electrical vehicle. According to a fourth aspect of the present disclosure, there is provided a method for controlling a battery system according to any one of the example embodiments of the first aspect of the disclosure. In particular, there is provided a method of disconnecting a battery unit in a battery system comprised in a vehicle, the battery system comprising a first electric conductor, a second electric conductor and a first battery unit arranged therebetween to form a first electrical circuit for transferring of electrical energy, wherein the battery system further comprises a first controllable electromechanical contactor arranged between the first battery unit and the first electrical conductors, and a battery system control unit arranged in communication with the electromechanical contactor.

The method comprises the steps of receiving, at the battery system control unit, a control signal indicative of an operational parameter of the battery unit; and operating, by the battery system control unit, the electromechanical contactor to control the electrical connection between the first battery cell and the first electric conductor.

The battery system control unit typically operates the electromechanical contactor based on the control signal. By way of example, the battery system operates the

electromechanical contactor to cause a break in the electrical connection in response to the control signal indicating a deviation in the operational parameter of the battery unit. According to one example embodiment, the method is performed on a battery system in a vehicle during discharging and/or charging thereof. The method can be used for controlling the battery system of the vehicle electrical propulsion system. The sequences of the method are typically performed by the control unit, such as an electronic control unit.

By way of example, the user communication device is arranged to communicate with the battery system control unit in order to perform the method according to any one of the example embodiments as mentioned above in relation to the fourth aspect. That is, the battery system control unit receives a control signal indicative of an operational parameter of the battery unit, as described above according to any one of the example

embodiments. The battery system control unit thereafter transmits a signal to the user communication device being indicative of the operational parameter of the battery unit. Then, in response to a user (such as a driver), using the user communication device, a user control signal is transmitted to the battery system control unit. The user control signal typically comprises data indicative of user instructions to control the electrical connection between a battery unit, such as the first battery unit, and the electric conductor, such as the first electric conductor, according to any one of the example embodiments described above in relation to the first aspect, second aspect, the third aspect and the fourth aspect.

According to a fifth aspect of the present disclosure, there is provided a computer program comprising program code means for performing the steps of any one of the example embodiments of the fourth aspect when the program is run on a computer.

According to a sixth aspect of the present disclosure, there is provided a computer readable medium carrying a computer program comprising program code means for performing the steps of any one of the embodiments of the fourth aspect when the program product is run on a computer. Effects and features of the fourth, fifth and sixth aspects of the disclosure are largely analogous to those described above in connection with the first aspect, second aspect and third aspect.

Further features of, and advantages with, the present disclosure will become apparent when studying the appended claims and the following description. The skilled person realize that different features of the present disclosure may be combined to create embodiments other than those described in the following, without departing from the scope of the present disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as additional objects, features and advantages of the present disclosure, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments of the present disclosure, wherein:

Fig. 1 is a side view of vehicle in the form an electrical truck, the vehicle comprising an electric propulsion system having a battery system according to example embodiments of the disclosure;

Fig. 2a schematically illustrates parts of a battery system according to an example embodiment of the disclosure, the battery system comprises a battery module having a set of battery cells controllable according to an example embodiment of the disclosure during discharging and charging thereof; Fig. 2b schematically illustrates parts of a battery system according to another example embodiment of the disclosure, the battery system comprises a battery module having a set of battery cells controllable according to an example embodiment of the disclosure during discharging and charging thereof.

With reference to the appended drawings, below follows a more detailed description of embodiments of the disclosure cited as examples.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS OF THE DISCLOSURE

The present disclosure will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the disclosure are shown. The disclosure may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided for thoroughness and completeness. The skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Like reference character refer to like elements throughout the description.

Fig. 1 illustrates a vehicle in the form of an electrical truck 5. The electrical truck is here a fully electrical vehicle, which is typically entirely powered by an electrical energy storage system such as a battery system. The electrical truck 5 comprises an electrical propulsion system 20 configured to provide traction power to the vehicle. The electrical propulsion system 20 provides electrical power to an electrical motor. However, the electrical propulsion system can also be adapted to manage various electronic functions of the vehicle. The electrical propulsion system comprises the electrical energy storage system 10 and the electrical motor 7. The electrical energy storage system 10 is connected to the electrical motor to provide power to the electrical motor, thereby the electrical motor can provide traction power to one or more ground engaging members, e.g. one or more wheels 80. The electrical energy storage system is a DC electrical energy storage system.

The DC electrical energy storage system 10 here comprises a battery system 4. The battery system typically includes a plurality of battery packs 1_a to 1 _n. By way of example, each one of the battery packs is a lithium-ion battery. Moreover, each one of the battery packs comprises a number of battery cells. In this context, the battery pack is a battery module comprising a plurality of battery cells 3. As such, each one of the battery packs 1 _a to 1 _n comprises a plurality of battery cells 3_a to 3_n. By way of example, the battery system comprises seven battery packs. The battery system 4 thus includes seven number of battery packs 1 _a - i_g, each one of them comprising a number of battery cells 3_a to 3_n. The battery system may comprise 50-500 battery cells. The number of battery packs in the battery system and the number of battery cells varies depending on type of vehicle and type of installation, etc.

Accordingly, the battery system 4 is arranged to provide electrical power to the electrical motor 7 arranged for providing propulsion for the electrical truck 5. Typically, the electrical truck 5 further comprises a control unit 8 configured to control and monitor the battery system 4. The control unit is here an electronic control unit. The electrical propulsion system 20 here comprises the control unit 8 including a battery system control unit 2 and the battery system 4. Typically, although strictly not required, the battery system control unit is further provided with a storage component adapted to store a battery equivalent model and battery characteristics for controlling the battery system, as will be further described in relation to Figs. 2a and 2b.

The battery system control unit 2 may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. Thus, the battery system control unit 2 comprises electronic circuits and connections (not shown) as well as processing circuitry (not shown) such that the battery system control unit 2 can communicate with the battery system.

The battery system control unit 2 is here arranged in electrical communication with the battery system 4. While the example embodiment described above includes a battery system control unit 2 being an integral part of the system 20, it is also possible that the control unit may be a separate part of the system 20 or even arranged remote from system 20, e.g. arranged at another location in the vehicle.

Turning now to Fig. 2a, there is depicted one example embodiment of a battery system according to the disclosure. Besides that the battery system here comprises the plurality of battery cells 3a to 3n, the battery system 4 also comprises a first electric conductor 36 and a second electric conductor 38. Each one of the first electric conductor 36 and the second electric conductor 38 is configured to transfer electrical energy. One example of an electrical conductor is a bus bar. In this example, each one of the electrical conductors is a so called main rail or bus bar, as is commonly known in the art.

As illustrated in Fig. 2a, the plurality of battery cells 3a to 3n are individually arranged in- between the first electric conductor 36 and the second electric conductor 38 to form a plurality of individual electrical circuits for transferring electrical energy.

By way of example, a first battery cell 3a is arranged between the first electric conductor 36 and the second electric conductor 38, thereby forming a first electrical circuit for transferring of electrical energy therebetween. Further, the battery system 4 comprises a first controllable electromechanical contactor 42a arranged between the first battery cell 3a and the first electrical conductors 36. The first controllable electromechanical contactor 42a is operable to control an electrical connection 43a between the first battery cell 3a and the first electric conductor 36. Hence, by the electrical connection 43a, there is provided an electrically conductive relationship between the battery cell 3a and the electrical conductor 36. The first controllable electromechanical contactor 42a is operable to connect and disconnect the battery cell 3a from the first electric conductor 36. Hereby, the first controllable electromechanical contactor 42a is arranged to isolate the first battery cell from receiving electrical current from the electrical conductor 36.

Moreover, as depicted in Fig. 2a, another electrical connection 45a is formed between the first battery cell 3a and the second electrical conductor 38.

It should be noted that a similar arrangement of an electromechanical contactor between a battery cell and the first electrical conductor is possible at a number of battery cells of the battery system. Thus, as also depicted in Fig. 2a, when the battery system comprises the plurality of battery cells 3a to 3n, each one of the battery cells is individually arranged in-between the first electric conductor 36 and the second electric conductor 38 to form a plurality of individual electrical circuits for transferring electrical energy. In a similar vein as the arrangement of the first electromechanical contactor, the battery system typically comprises a plurality of additional electromechanical contactors 42b to 42n arranged individually between each one of the plurality of battery cells 3b to 3n and the first electric conductor 36, respectively. As mentioned above, the battery system typically comprises the battery system control unit 2. As schematically illustrated in Fig. 2a, the battery system control unit 2 is arranged in electrical communication with the electromechanical contactors of the battery system. Moreover, the battery system control unit 2 is here configured to control actuation of the electromechanical contactor based on a control signal. The control signal typically refers to data indicative of a problem in the corresponding battery cell, as further described herein.

By way of example, the actuation of the electromechanical contactor is performed by providing a closed circuit in the electromechanical contactor. Hereby, the actuation of the electromechanical contactor causes a closed circuit in the electrical connection. Typically, the actuation of the electromechanical contactor forms a closed circuit in the electrical connection when receiving the control signal from the battery systems control unit.

Further, in this example, the electromechanical contactor is configured to form the closed circuit in the electrical connection by energizing the electromechanical contactor. By way of example, actuation of the electromechanical contactor is performed by receiving an electrical current, e.g. a low current or low voltage. The electrical current may be provided by the battery system 4. Alternatively, the electrical current can be provided by another battery in the vehicle, a so called low voltage battery (e.g. a 12V or 24V battery system). Hence, energization is provided e.g. by controlling an electrical current through the electromechanical contactor. When the electromechanical contactor is actuated, e.g. the electromechanical contactor forms the closed circuit, a flow of electrical current is permitted to flow in the electrical connection, referring e.g. to the first electrical connection 43a.

As mentioned above, the actuation of the electromechanical contactor is performed based on the control signal from the battery system control unit 2.

Typically, battery system control unit 2 is also configured to determine a deviation in an operational property of the battery cell. One example of an operational property is voltage. Other conceivable examples of operational properties may be electrical current, temperature or a combination thereof. Also, the battery system control unit 2 is here configured to detect a malfunction of the battery unit. By way of example, the control signal indicates the malfunction of the battery cell. By way of example, the battery system control unit 2 is configured to determine a deviation in voltage through the battery cell. That is, the battery system control unit 2 is configured to determine a voltage drop. The deviation in the operational property of the battery cell here reflects a malfunction of the battery unit.

Accordingly, the battery system control unit 2is configured to detect a malfunction of the battery cell, and the control signal indicates the malfunction of the battery cell. The battery system control unit may optionally cooperate with a sensor device to detect the malfunction, as described e.g. in relation to the example embodiment depicted in Fig. 2b.

As mentioned above, the electromechanical contactor is arranged to disconnect or isolate the battery cell from electrical conductor, i.e. to prevent electrical current to flow through the battery cell. To this end, the electromechanical contactor is configured to cause a break in the electrical connection between the battery cell and the first electric conductor in response to receiving the control signal indicating a malfunction in the battery cell. Hence, the break or interruption in the electrical connection causes a disconnection of the battery cell from the first electrical conductor.

Assuming e.g. that the battery cell 3a is subject to a voltage drop compared to the other battery cells. The state of the battery cell may be monitored and detected by the configuration of the control unit itself, or by one or several sensor devices in

communication with the control unit 2. As a response to the detected state of the battery cell, the control unit 2 receives a signal indicative of the state of the battery cell.

Subsequently, the control unit 2 transmits a control signal to the electromechanical contactor to cause a break in the electrical connection between the battery cell 3a and the first electrical conductor 36. In this manner, charging or discharging of the battery cell 3a is temporarily interrupted by the electromechanical contactor 42a.

Turning now Fig. 2b, there is depicted another example embodiment of a battery system according to the disclosure. Besides that the battery system described in relation to Fig. 2b may comprise any one of the features, functions and examples as described in relation to Fig. 2a, the battery system in Fig. 2b further comprises a second controllable electromechanical contactor 44a arranged between the first battery cell 3a and the second electrical conductor 38. Also, the second controllable electromechanical contactor 44a is operable to control an electrical connection 45a between the first battery cell 3a and the second electric conductor 38. Similar to the example described in relation to Fig. 2a, the battery system here typically comprises a plurality of additional electromechanical contactors 44b to 44n arranged individually between each one of the plurality of battery cells 3b to 3n and the second electric conductor 38, respectively. Accordingly, there is provided a number of second controllable electromechanical contactors 44a to 44n operable to control a number of electrical connections 45a to 45n. Each one of the electromechanical contactors of the number of second controllable electromechanical contactors 44a to 44n is individually arranged between the number of battery cells 3a - 3n and the second electric conductor 38.

Moreover, while still referring to Fig. 2b, the battery system here comprises a sensor device 80 arranged in proximity to the battery cells 3a to 3n. The sensor device 80 is configured to detect a hazardous operational condition of the battery unit, such as smoke, fire etc. that may occur in an over-heated battery cell of the battery system. In one example, the sensor device is a wireless video device. In addition, or alternatively, the sensor device is a smoke detector, gas detector or a fire detector.

Optional, as depicted in Fig 2b, the battery system 4 further comprises a user

communication device 9 in networked communication with the battery system control unit. The user communication device is here a remote control unit. Further, the user communication device may be configured to communicate directly with one or several of the electromechanical contactors 42a to 42n. In this example, the user communication device is part of a software installed in a portable device of a driver of the vehicle. The user communication device is here arranged to communicate with the electromechanical contactors of the battery system, the battery system control unit 2 and the sensor device 80.

The battery system as described to any one of the example embodiments in Figs. 2a and 2b can be controlled according to the following sequences. The sequences of the method are typically performed by the battery system control unit 2, such as an electronic control unit, as described above in relation to the Fig. 1. In addition, or alternatively, the sequences of the method may be performed by means of the user communication device 9, which is in networked communication with the battery system control unit.

Thus, in a first step, the battery system control unit 2 receives a control signal indicative of an operational parameter of the battery cell. In a subsequent step, the battery system control unit operates the electromechanical contactor to control the electrical connection between the first battery cell and the first electric conductor. Typically, the battery system operates the electromechanical contactor to cause a break in the electrical connection in response to control signal indicating a deviation in the operational parameter of the battery cell.

The sequences of the methods can be performed by the battery system control unit 2 during charging and/or discharging of the battery system. The deviation of the operational parameter of the battery cell is typically determined by means of the sensor unit, as described above in relation to Fig. 2b. It is to be noted that the steps of the method is typically performed by the battery system control unit 2 during use of the battery system by the electrical propulsion system. It is also to be noted that the state of the battery cells of the battery system are typically obtained by measurements on the battery cells. It should also be noted that the order of the steps may differ from what is described above. Also two or more steps may be performed concurrently or with partial concurrence. Such variation will depend on the software and hardware systems chosen and on designer choice. All such variations are within the scope of the disclosure. Likewise, software implementations could be accomplished with standard programming techniques with rule based logic and other logic to accomplish the various connection steps, processing steps, comparison steps and decision steps.

For the sake of simplicity, it should be noted that while the battery system typically comprises a large number of battery cells, the example embodiments of the disclosure have mainly been described with reference to one battery cell or a number of battery cells as illustrated in Figs. 2a and 2b. Thus, it should be noted that although the Figs. 2a - 2b illustrate some examples of disconnecting or isolating one battery cell 3a by using one or two electromechanical contactors 42a and 44a, the examples may likewise be used for disconnecting or isolating any one of the other battery cells by means of a corresponding electromechanical contactor.

Additionally, even though the disclosure has been described with reference to specific exemplifying embodiments thereof, many different alterations, modifications and the like will become apparent for those skilled in the art. By way of example, the example embodiments of the steps, the features of the system and the various equations are applicable for controlling the battery system during charging and/or discharging of the battery system. It is to be understood that the present disclosure is not limited to the embodiments described above and illustrated in the drawings; rather, the skilled person will recognize that many changes and modifications may be made within the scope of the appended claims.

Claims

1. A battery system (4) for a vehicle (5) comprising a first electric conductor (36), a second electric conductor (38) and a first battery unit (3a to 3n) arranged therebetween to form a first electrical circuit for transferring of electrical energy, wherein the battery system further comprises a first controllable electromechanical contactor (42a to 42n) arranged between the first battery unit and the first electric conductor, and operable to control an electrical connection between the first battery unit and the first electric conductor.

2. Battery system according to claim 1 , wherein the battery system further comprises a second controllable electromechanical contactor (44a to 44n) arranged between the first battery unit and the second electric conductor, and operable to control an electrical connection between the first battery unit and the second electric conductor.

3. Battery system according to any one of the preceding claims, wherein the battery system comprises a plurality of battery units individually arranged in-between the first electric conductor and the second electric conductor to form a plurality of individual electrical circuits for transferring electrical energy, a plurality of additional electromechanical contactors arranged individually between each one of the plurality of battery units and the first electric conductor, respectively, and individually between each one of the plurality of battery units and the second electric conductor, respectively.

4. Battery system according to any one of the preceding claims, further comprising a battery system control unit arranged in communication with the electromechanical contactor and configured to control actuation of the electromechanical contactor based on a control signal.

5. Battery system according to claim 4, wherein the battery system control unit is an electronic control unit comprised on-board the vehicle.

6. Battery system according to any one of the claims 4 to 5, wherein the battery system control unit further comprising a user communication device (9) in networked communication with the battery system control unit.

7. Battery system according to any one of the claims 4 to 6, wherein the battery system control unit further is configured to determine a deviation in an operational property of the battery unit.

8. Battery system according to any one of the claims 4 to 7, wherein the battery system control unit is configured to detect a malfunction of the battery unit, and the control signal indicates the malfunction of the battery unit.

9. Battery system according to any one of the claims 4 to 8, wherein the

electromechanical contactor is configured to cause a break in the electrical connection between the battery unit and the first electric conductor in response to receiving the control signal.

10. Battery system according to any one of the preceding claims, further comprising a sensor device arranged in proximity to the battery unit and configured to detect a hazardous operational condition of the battery unit.

1 1. Battery system according to claim 10, wherein the sensor device is any one of a wireless video device, a smoke detector, a fire detector, a gas detector, a flame detector and a liquid detector.

12. Battery system according to any one of the preceding claims, wherein the battery unit is one of a battery cell or a battery module comprising a number of series connected battery cells.

13. A vehicle electrical propulsion system comprising an electric machine and a

battery system according to any one of claims 1 to 12 and, wherein the battery system is configured to provide electric power to the electric machine.

14. A vehicle (5), comprising a battery system according to any one of the claims 1 to 12 or a vehicle propulsion system according to claim 13.

15. A method of disconnecting a battery unit in a battery system comprised in a

vehicle, the battery system comprising a first electric conductor, a second electric conductor and a first battery unit arranged therebetween to form a first electrical circuit for transferring of electrical energy, wherein the battery system further comprises a first controllable electromechanical contactor arranged between the first battery unit and the first electrical conductors, and a battery system control unit arranged in communication with the electromechanical contactor, the method comprising the steps of: receiving, at the battery system control unit, a control signal indicative of an operational parameter of the battery unit; and

operating, by the battery system control unit, the electromechanical contactor to control the electrical connection between the first battery cell and the first electric conductor.

16. A computer program comprising program code means for performing the steps of claim 15 when said program is run on a computer.

17. A computer readable medium carrying a computer program comprising program means for performing the steps of claim 15 when said program means is run on a computer.