TECHNICAL FIELD

The invention relates to a method of managing electric power supply of a vehicle, and to a system for managing electric power supply of a vehicle. BACKGROUND

In the field of vehicles, there is a steady increase in research and development related to propulsion of vehicles with alternative power sources, i.e. power sources being used as alternatives to conventional internal combustion engines. In particular, electrically operated vehicles has emerged as a promising alternative. According to the current state of art, a vehicle can be operated by means of an electric machine solely or by means of an arrangement comprising both an electric machine and an internal combustion engine. The latter alternative is often referred to as a hybrid vehicle (HEV), and can for example be utilized in a manner in which an internal combustion engine is used for operating the vehicle while driving outside urban areas whereas the electric machine can be used in urban areas or in environments in which there is a need to limit the discharge of harmful pollutants such as for example carbon monoxide and oxides of nitrogen.

The technology involved in electrically operated vehicles is closely related to the development of electrical energy storage systems (ESS). An electrical energy storage system may comprise at least one battery pack with a plurality of rechargeable battery cells which, together with control circuits, form a system which is configured for providing electric power to an electric machine in a vehicle.

It is known that batteries undergo power transfer. The power transfer should in the present context be interpreted as a charging or discharging cycle of the battery. Charging and discharging may also be referred to as power input to or output from the battery. The state of art provides several ways in which batteries may be charged, such as OppCharge, CCS, CHAdeMO or the like. When the energy level of a battery is low, the battery needs power input in order to restore its energy level. Usually, the battery receives power input from external power source, such as power grid. When a vehicle is connected to an external power grid, it is expected that the power available from the grid is used to charge the batteries. However, a charging session may fail, either due to power outage in the external power grid, or due to an expected pause in scheduled charging sequence. Upon failure of the charging session, the vehicle is normally shut down until the power supply from the external power grid is resumed. While being shut down, the vehicle is unable to perform any operations such as maintaining a charge level in the 24V batteries or heating/cooling of the interior space of the vehicle or the ESS.

JP2001054239 describes a load-leveling system provided with a power failure detecting circuit 6 and a changeover switch 5. The load leveling system supplies AC power to a load 2 from a commercial power source 1 and charges a storage battery 3 by converting AC power to DC power with a bidirectional inverter 4 at nights and uninterruptedly supplies the AC power converted from the DC power from the storage battery 3 with the two-way inverter 4 to the load 2 during day time. The power failure detecting circuit 6 detects the power failure of the commercial power source 1 at nights, while the changeover switch 5 stops charging the storage battery 3 based on a signal from the power failure detecting circuit 6 and converts the DC power from the storage battery 3 into the AC power using the bidirectional inverter 4 to supply power to the load 2.

In view of the above, there is still a need for an improved method of managing power transfer of ESS, in particular when the charging session is interrupted.

SUMMARY

The present invention thus provides a method of managing electric power supply of a vehicle, wherein the vehicle comprises an energy storage system (ESS) being an internal electric power source, wherein the vehicle further comprises auxiliaries, and wherein the vehicle is connectable to an external electric power source, the method comprising the steps of: a) connecting the vehicle to the external electric power source;

b) charging the ESS of the vehicle and providing the vehicle with electric power from the external electric power source; c) in case the electric power supply from the external electric power source is interrupted, stopping the charging of the ESS of the vehicle and providing the vehicle with electric power from the internal electric power source; in case the electric power supply from the external power source is re established, resuming the charging of the ESS of the vehicle and seamlessly switching to providing the vehicle with electric power from the external electric power source.

The term "energy storage system (ESS)" should in the following and throughout the entire description be interpreted as an electrical energy storage system comprising at least one battery pack with a plurality of rechargeable battery cells which, together with an electronic control unit (ECU), forms a system which may be used for electrical propulsion of a vehicle, and/or for providing electric power to auxiliary loads, such as air conditioning system, pneumatics, or the like. The voltage of the ESS may be 400-1000 V. The electric system of the vehicle being connected to the ESS will herein be referred to as traction voltage circuit.

The first step a) of the method according to the present invention is connecting the vehicle to the external electric power source. The external electric power source may be power grid. Alternatively, the external electric power source may be a portable charging station, such as another vehicle. The connection of the vehicle to the external power source may be achieved through a plug-in contact, a pantograph or an ERS. Further, the connection of the vehicle to the external power source may be achieved inductively.

In the next step b), charging of the ESS of the vehicle occurs, wherein electric power is transferred from the external power source to the ESS of the vehicle. Several known methods of charging the ESS are available, such as CSS, CHAdeMO, OppCharge or the like. When the vehicle receives electric power from the external power source, the external electric power source provides electric power to the vehicle, in particular to the auxiliaries of the vehicle.

Step c) of the method is provided for improved handling of the electric supply to the vehicle in case the electric power supply from the external electric power source is interrupted. In case of such an interruption, charging of the ESS of the vehicle is terminated. However, rather than shutting down the entire vehicle, the power supply to the vehicle is seamlessly switched from the external power source to the internal power source, such that the vehicle may continue to function. According to step d) of the present invention, if or when the electric power supply from the external power source is re-established, the charging of the ESS of the vehicle is resumed and the electric power supply is seamlessly switched from the internal to the external electric power source. In other words, when the electric power from the external power source is re-established, the battery control unit would request the ESS of the vehicle to charge again, and the vehicle would seamlessly continue to perform the tasks done by the auxiliaries, but now using power from the external rather than internal power source.

The method of the present invention may comprise at least one sub-step, such as verifying whether power supply from the external power source has been interrupted or restored, or whether requesting information on whether the vehicle and its auxiliaries need power.

The electric power from the internal electric power source in step c) and the electric power from the external electric power source in step d) may be used for providing electric power to the auxiliaries of the vehicle. Such auxiliaries of the vehicle may be the heating/cooling system for the ESS, heating/cooling system for the interior of the vehicle, including the cab and the cargo space, pneumatic and hydraulic systems or the like. The auxiliaries may be powered either directly by the internal power source (ESS) or by a low voltage circuit described in greater detail below, which in turn receives power supply from the internal power source.

The vehicle may comprise a low voltage circuit, such as a 12 V or 24 V circuit. Such a low voltage circuit is oftentimes used for powering audio system, GPS navigator, phone chargers or the like. The low voltage circuit is considered as auxiliaries in the context of the present invention, and may be powered by the internal electric power source (ESS) according to step c) of the method of the present invention.

The low voltage circuit may comprise low voltage batteries that may be charged either from the external or the internal power source via a DC/DC converter.

According to the method of the present invention, the vehicle will choose its best power supply available at any time to perform secondary actions described above. If the electric power form the external power source, e.g. a grid, is available, the charger is working and allows charging, then power from the grid shall be taken. Otherwise, powerfrom the internal power source, e.g. the vehicle’s own 600V batteries, shall be taken. The method according to the present invention may be used when the vehicle is moving. Alternatively, the method of the present invention may be used when the vehicle is at stand still. Thus, the vehicle may be parked at the charging station.

The charging station in the context of the present invention may be any point being equipped with at least one electric outlet connected to an external electric power source, such as a power grid. The charging station may comprise a plurality of electric outlets, and may be equipped with a control unit for scheduling charging sessions depending on the capacity of the charging station and the number of vehicle being connected to the charging station. Further, a charging station may also be any point equipped with means for inductive charging.

As mentioned above, the present invention provides an improved method for handling interruptions in external power supply to the ESS of the vehicle, wherein an interruption in the external power supply causes the power supply to be switched to the internal power supply from the ESS, rather than shutting down the entire vehicle. According to the method of the present invention, the auxiliaries may be operating although no external power supply is available.

As mentioned above, the auxiliaries may be at least one of heating and/or cooling system for ESS and heating and/or cooling system for the interior space of the vehicle, such as the cab and the cargo space. Indeed, having the heating and/or cooling system running without interruptions may be very important for comfort of the driver and function of the vehicle.

As mentioned above, the external power source may be the power grid. Interruptions in the external power supply may occur due to the outage in the power grid, e.g. due to electrical breakdown or other damage in a cable.

Interruptions in the external power supply may also arise from a planned pause in a scheduled charging. Such a pause may be requested by the charging station depending on the capacity of the charging station as well as the amount and state of vehicles requesting charging.

As mentioned above, the steps of the method according to present invention may be performed by at least one ECU. Such an ECU typically refers to a control unit of an ESS, herein also referred to as battery control unit. The control unit may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. Thus, the control unit comprises electronic circuits and connections as well as processing circuitry such that the control unit can communicate with different parts of the electric power transmission system and any other parts in need of being operated in order to provide the functions of the example embodiments. Depending on the type of control unit and location of the control unit, the control unit may also be configured to communicate with other parts of the vehicle such as the electrical machines, 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 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 control unit typically comprises a non-transistory memory for storing computer program code and data upon. Thus, the control unit may be embodied by many different constructions.

Further, the method of the present invention may involve a vehicle control unit. The vehicle control unit may be used for communicating with the battery control unit, and providing information regarding the power request from the vehicle including its auxiliaries.

The present invention further relates to a system for managing electric power supply of a vehicle, wherein the vehicle comprises an energy storage system (ESS) being an internal electric power source, wherein the vehicle further comprises auxiliaries, and wherein the vehicle is connectable to an external electric power source. The system is configured to charge the ESS of the vehicle and provide the vehicle with electric power from the external electric power source in case the vehicle is connected to and receives electric power from the external electric power source. Further, the system is configured to stop the charging of the ESS of the vehicle and provide the vehicle with electric power from the internal electric power source in case the electric power supply from the external electric power source is interrupted. Finally, the system is configured to resume the charging of the ESS of the vehicle and seamlessly switch to providing the vehicle with electric power from the external electric power source in case the electric power supply from the external power source is re-established.

The control functionality of the example embodiments of the system for managing electric power supply 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 system for managing electric power supply described above can include a 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 and in communication with the system for managing electric power supply.

The system of the present invention may be used when the vehicle is at stand-still. Alternatively, the system of the present invention may be used when the vehicle is moving.

In the system of the present invention, the electric power from the internal electric power source and the electric power from the external electric power source may be used for providing electric power to the auxiliaries, such as the heating/cooling system for the ESS, heating/cooling system for the interior of the vehicle, including the cab and the cargo space, pneumatic and hydraulic systems or the like. As mentioned above, the auxiliaries may be powered either directly by the internal power source (ESS) or by a low voltage circuit, which in turn receives power supply from the internal power source via a DC/DC converter.

The present invention further relates to a vehicle comprising the system as described above. Finally, the present invention relates to a computer program comprising program code means for performing the steps c) and d) of the method described above, as well as a computer readable medium carrying a computer program comprising program code means for performing the steps c) and d) of the method disclosed above when the program means is run on a computer.

The invention can be applied in any type of hybrid vehicles or electrical vehicles, such as partly or fully electrical vehicles. Although the invention will be described with respect to an electrical bus, the invention is not restricted to this particular vehicle, but may also be used in other hybrid or electrical vehicles such as electrical truck, electrical construction equipment, and electrical cars.

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

BRIEF DESCRIPTION OF THE DRAWINGS

The above, as well as additional objects, features and advantages of the present invention, will be better understood through the following illustrative and non-limiting detailed description of exemplary embodiments of the present invention, wherein: Fig. 1 is a flow chart outlining the steps of a method according to the invention;

Fig. 2 schematically illustrates a vehicle comprising a system for managing electric power supply according to the invention;

With reference to the appended drawings, below follows a more detailed description of the invention cited as examples. DETAILED DESCRIPTION OF THE INVENTION

The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplary embodiments of the invention are shown. The invention 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 changes and modifications may be made within the scope of the appended claims.

Fig. 1 is a flow chart outlining the steps of a method 100 according to the present invention. The method of Fig. 1 will be described with further reference to the vehicle 201 comprising a system for managing electric power supply 200 illustrated in Fig. 2. In particular, Fig. 1 outlines a method of managing electric power supply of a vehicle 201 , wherein the vehicle comprises an energy storage system 202 (ESS) being an internal electric power source, wherein the vehicle further comprises auxiliaries (not shown), and wherein the vehicle is connectable to an external electric power source 210.

Fig. 2 schematically illustrates a battery control system 200 comprising a vehicle control unit 208 which can send requests to the battery control unit 204. The vehicle control unit 208 may be a dedicated control unit configured to control a hybrid or electrical propulsion system, or it may be a general purpose vehicle control unit. The battery control unit 204 may include a microprocessor, microcontroller, programmable digital signal processor or another programmable device. Thus, the battery control unit 204 comprises electronic circuits and connections (not shown) as well as processing circuitry (not shown) such that the battery control unit 204 can communicate with different parts of the vehicle 201 such as the brakes, suspension, driveline, in particular an electrical engine, an electric machine, a clutch, and a gearbox in order to at least partly operate the vehicle 201. The battery control unit 204 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 control unit 204 comprises a non-transitory memory for storing computer program code and data upon. Thus, the person skilled in the art realizes that the battery control unit 204 may be embodied by many different constructions.

Fig. 2 further illustrates that the vehicle 201 may be connected to charging station 210. Accordingly, the charging station 210 is the external power source in the context of the present invention.

In the first step a), the vehicle 201 is connected to the external electric power source, such as a charging station 210. The battery control unit 204 receives information regarding connection to the external power source 210, and permits power transfer from the external power source 210 to the vehicle 201 according to step b). In particular, the electric power being transferred from the external power source 210 to the vehicle 201 is used for charging the ESS 202 of the vehicle as well as powering the auxiliaries (not shown).

As the next step, the ESS control unit 204 provides a response indicative whether the power supply from the external power source is interrupted. The response may be a Boolean response, i.e. "YES" or "NO", or any equivalent predetermined Boolean response (e.g. "1 " or "0") indicating compliance or non-compliance with the power supply from the external power source. If the answer is NO, the method proceeds to sub-step 101 , wherein the power transfer from the external power source continues. If the answer is YES, the method proceeds to sub-step 102.

According to sub-step 102, the battery control unit 204 communicates to the vehicle control unit 208 that the power supply from the external power source 210 has been interrupted, and requests information from the vehicle control unit 208 whether power is needed for continuous operation of the auxiliaries. Analogous to the above, the vehicle control unit 208 provides a Boolean response, i.e. "YES" or "NO", or any equivalent predetermined Boolean response (e.g. "1 " or "0"). If the answer is NO, the method proceeds to sub-step 103 and shuts down the vehicle. If the answer is YES, the method proceeds to step c).

According to step c) of the method of the present invention, the battery control unit 204 will request that charging of ESS 202 is interrupted and that the auxiliaries are powered from the internal power source (ESS) 202, as described above.

Finally, the battery control unit 204 will monitor whether the power supply from the external power source 210 is restored according to sub-step 105. If the power supply from the external power source 210 is not restored, the auxiliaries will continue to be powered from the ESS 202. As soon as the power supply from the external power source 210 has been re-established, the battery control unit 204 will allow charging of the ESS 202 to be resumed. Moreover, power transfer to the auxiliaries will seamlessly be switched from the internal power source 202 to the external power source 210.

The control functionality of the example embodiments 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.

It is to be understood that the present invention 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. For example, although the present invention has mainly been described in relation to an electrical bus, the invention should be understood to be equally applicable for any type of electrical vehicle.