SE2150239A1

SE2150239A1 - Method and control arrangement for operating an electrical motor of a vehicle

Info

Publication number: SE2150239A1
Application number: SE2150239A
Authority: SE
Inventors: Daniel Ekenberg; Joel Axelsson; Niklas Berglund
Original assignee: Scania Cv Ab
Priority date: 2021-03-03
Filing date: 2021-03-03
Publication date: 2022-09-04
Also published as: DE102022103431A1

Abstract

A method for operating an electrical motor system of a vehicle, the method comprising:predicting a set of temperature profiles for the electrical motor system in an upcoming road section based on a set of speed profiles for the upcoming road section and information associated with the upcoming road section, wherein each temperature profile in the set of temperature profiles is associated with a speed profile in the set of speed profiles and an operating temperature of the electrical motor system;determining a power outtake for the electrical motor system based on a temperature profile in the set of temperature profiles based on its threshold temperature in the upcoming road section; andoperating the electrical motor system in the upcoming road section according to the determined power outtake.Hereby, the electrical motor system may be efficiently utilized with increased efficiency, driving range performance and durability.The invention relates also to a control arrangement, a vehicle comprising the control arrangement, a computer program and a computer-readable medium.

Description

METHOD AND CONTROL ARRANGEMENT FOR OPERATING AN ELECTRICALMOTOR OF A VEHICLE Technical fieldThe invention relates to a method and a control arrangement for operating an electricalmotor system of a vehicle allowing a preferred power outtake from the electrical motor system.

The invention also relates to a computer program and a computer-readable medium and a vehicle comprising such a control arrangement.

BackgroundThe following background description constitutes a description of the background to the invention, which does not, however, necessarily have to constitute prior art.

One of the major global challenges today is reducing the negative impacts of roadtransportation on the environment due to greenhouse gas emissions. Moreover, inmotor vehicles, such as cars, trucks and buses, the cost of fuel constitutes a significantexpense for the vehicle's owner or user. This has led to an increased interest in vehicleelectrification. The powertrain of vehicles powered at least partly by electrical power,i.e. electrical and hybrid vehicles, comprises an electrical motor system with a batteryserving as an energy buffer and at least one electrical motor. Electric vehicles areexpected to efficiently and reliably deliver a propulsion power and energy requested todrive the vehicle at a required speed as well as braking power and energy to efficientlyand safely brake the vehicle when required. The vehicle performance and driving range may be enhanced by efficient utilization of the powertrain.

The performance of the electrical motor system is limited for one or more reasons forexample by its thermal capability. The electrical motor system in a vehicle will operateefficiently and safely within its safe operating temperature. A safe operatingtemperature is often limited by a maximum operating temperature in one or more components of the system. When exposed to temperatures above the maximum lO operating temperature, the lifetime of the components of the electrical motor system is decreasing. Too high temperatures may also lead to component failure.

Electrical vehicles powered solely by electrical power need to be dimensioned towithstand high power demand. During normal conditions, power demand on theelectrical vehicle may be relatively low. However, to be able to cope with long periodsof high-power and temperature demands, electrical motor systems are often over-dimensioned, heavy, large, and expensive. On the other hand, poorly dimensionedelectrical motor systems may not be able to provide a required power during situationswhen the power output is thermally limited in some parts of the electrical motor system.This may be become a problem in vehicles with relatively small powertrains.

Today, in modern vehicles, the operating temperatures of various components of anelectrical motor system are often monitored. ln situations when an operatingtemperature exceeds a desired temperature limit a common solution is to reduce theload on the engine e.g. by electronically limiting the engine power output. The torquegenerated by the engine is thereby reduced which may lead to reduced vehicle speedor even to braking the vehicle to standstill. However, this solution reduces the overallperformance of the vehicle. ln hybrid vehicles, the power provided by the electrical motor system may not limitingthe propulsion of the vehicle since a tractive force may be produced by the vehicle'sinternal combustion engine. However, an efficient and lightweight electrical motorsystem may reduce the fuel consumption of the hybrid vehicle.

Summaﬂlt is an objective of the present invention to provide a method and a control arrangement for mitigating or solving drawbacks of conventional solutions. ln particularan objective of the present invention is to provide a solution for operating an electricalmotor system of a vehicle preventing the hardware limitations of the electrical motor system to be reached. lO According to a first aspect of the invention, aforementioned and further objectives areachieved through a method for operating an electrical motor system of a vehicle, themethod comprising: predicting a set of temperature profiles for the electrical motor system in anupcoming road section based on a set of speed profiles for the upcoming road sectionand information associated with the upcoming road section, wherein each temperatureprofile in the set of temperature profiles is associated with a speed profile in the set ofspeed profiles and an operating temperature of the electrical motor system; determining a power outtake for the electrical motor system based on atemperature profile in the set of temperature profiles based on its thresholdtemperature in the upcoming road section; and operating the electrical motor system in the upcoming road section according to the determined power outtake.

An electrical motor system may here comprise an electrical motor, power electronicsand a related battery system. The temperature in the components of the electricalmotor system will vary over time depending mainly on the power outtake from theelectrical motor system when tractive or braking power is provided from the electricalmotor in the vehicle to the vehicle's drive wheel when the vehicle is in motion. Such temperature variation corresponds to above mentioned temperature profile.

Each temperature profile from the set of predicted temperature profiles may beassociated with a speed profile such that each temperature profile may correspond toone specific speed profile. Each temperature profile from the set of predictedtemperature profiles may furthermore be associated with an operating temperature ofthe electrical motor system in that each temperature profile may comprise atemperature change in one or more components of the electrical motor system as afunction of time when the electrical motor provides tractive or braking power to propelor brake the vehicle in the upcoming road section according to the correspondingspeed profile. The operating temperature of the one or more components may differ depending on the component. lO Information associated with an upcoming road section for the vehicle may be relatedto conditions which may e.g. impact a power and thermal demand on the vehicle'selectrical motor system when the vehicle is driving in the upcoming road section. Suchconditions may comprise upcoming road topology, expected velocity requirements, ambient temperature etc.

By predicting a set of temperature profiles for the electrical motor system in anupcoming road section based on a set of speed profiles for the upcoming road sectionand information associated with the upcoming road section, a temperature variation indifferent components of the electrical motor system may be estimated when a powerouttake from the electrical motor system corresponds to the power needed to propelthe vehicle in the upcoming road section according to a corresponding speed profile.

By determining a power outtake for the electrical motor system in the upcoming roadsection based on the temperature profile for the electrical motor system and operatingthe electrical motor system in the upcoming road section according to the powerouttake for the electrical motor system, the electrical motor system the risk of meeting a thermal limitation in the electrical motor system is mitigated.

Hereby, the electrical motor system may be efficiently utilized with increased efficiency,driving range performance and durability. The driver of the vehicle will get the feelingthat he or she has more power available compared to the size of the motor in thevehicle. The need of dimensioning margins, development costs and weight of thesystem will be reduced providing increased sustainability. Moreover, by applying thesolution according to the invention in hybrid vehicles may also improve fuel efficiencyof the vehicle due decreased vehicle weight as well as increased electrical motor system efficiency. ln an embodiment of the invention each speed profile in the set of speed profiles hasan average speed, and the determining the power outtake for the electrical motor system is further based on the average speed of each individual speed profile. lO By determining the power outtake for the electrical motor system based on the averagespeed of each individual speed profile, the speed of the vehicle may be controlled in a desired way. ln an embodiment of the invention the average speed of the speed profile is the highest average speed in the upcoming road section.

Hereby the risk of unwanted speed decrease due to thermal limitations in the electrical motor system may be mitigated. ln an embodiment of the invention the determining of the power outtake for theelectrical motor system takes into account the energy consumption of the electricalmotor system in the upcoming road section.

By determining the power outtake for the electrical motor system taking into accountthe energy consumption of the electrical motor system in the upcoming road section,the energy consumption of the vehicle may be controlled and limited.

Hereby the range of the vehicle may be increased. ln an embodiment of the invention the determining of the power outtake for theelectrical motor system takes into account wear on the electrical motor system in the upcoming road section.

Hereby, the electrical motor system can be controlled in a safe way, limiting the wearon the components of the electrical motor system, and mitigating the risk of decreased lifetime of the electrical motor system. ln an embodiment of the invention the method further comprisingpredicting the set of temperature profiles further based on vehicle configuration data for the vehicle. lO By predicting the set of temperature profiles further based on vehicle configuration datafor the vehicle the temperature profiles may be modeled and predicted in a precisemanner for different types of vehicles. Poor modeling of the thermal limitation in theelectrical motor system may lead to inadequate control of the electrical motor systemin the vehicle.

Hereby, the electrical motor system may be controlled in an accurate way mitigatingthe risk of component aging and decreased efficiency of the electrical motor systemand decreased vehicle drivability. ln an embodiment of the invention the vehicle configuration data is one or more of: acurrent weight, a vehicle model, a type of gearbox, a drive line configuration, an axleconfiguration and type of tires.

Hereby, the temperature profiles may be predicted in a precise manner taking intoconsideration the vehicle configuration data which may impact the thermalcharacteristics of the electrical motor system. ln an embodiment of the invention the information associated with the upcoming roadsection is one or more of: topographic data, cartographic data, traffic data and vehicle-to-everything interaction data.

Hereby, the information associated with the upcoming road section may be anyinformation that may impact the thermal characteristics of the electrical motor system.Thus, the electrical motor system may be controlled in a reliable and accurate waymitigating the risk of component aging and decreased efficiency of the electrical motor system and decreased vehicle drivability. ln an embodiment of the invention the method further comprising predicting the set oftemperature profiles further based on a set of power loss profiles for the electrical motor system in the upcoming road section. lO By predicting the set of temperature profiles further based on a set of power lossprofiles for the electrical motor system in the upcoming road section ensures a reliableand accurate temperature prediction taking into account the efficiency of the electricalmotor system during different loading conditions.

Hereby, the electrical motor system may be controlled in a reliable and accurate waymitigating the risk of component aging and decreased efficiency of the electrical motor system and decreased vehicle drivability. ln an embodiment of the invention the operating temperature is one or more of: atemperature of a winding, a temperature of power electronics, a temperature of apermanent magnet of the electrical motor system, a temperature of a battery cell in the battery system and a temperature of a battery pack in the battery system.

Hereby the risk of degradation, shortened the lifetime or failure of the components of the electrical motor system is mitigated.

According to a second aspect, the invention relates to a control arrangement forcontrolling an electrical motor system of a vehicle, the control arrangement beingconfigured to predict a set of temperature profiles for the electrical motor system in anupcoming road section based on a set of speed profiles for the upcoming road sectionand information associated with the upcoming road section, wherein each temperatureprofile in the set of temperature profiles is associated with a speed profile in the set ofspeed profiles and an operating temperature of the electrical motor system; determine a power outtake for the electrical motor system based on atemperature profile in the set of temperature profiles based on its thresholdtemperature in the upcoming road section; and operate the electrical motor system in the upcoming road section according to the determined power outtake. lt will be appreciated that all the embodiments described for the method aspects of theinvention are applicable also to at least one of the control arrangement aspects of the lO invention. Thus, all the embodiments described for the method aspects of the inventionmay be performed by the control arrangement, which may also be a control device, i.e.a device. The control arrangement and its embodiments have advantagescorresponding to the advantages mentioned above for the methods and theirembodiments.

According to a third aspect of the invention, aforementioned and further objectives areachieved through a vehicle comprising the control arrangement of the second aspect.The vehicle may for example be a bus, a truck, or a car.

According to a fourth aspect, the invention relates to a computer program comprisinginstructions which, when the program is executed by a computer, cause the computerto carry out the method according to the first aspect.

According to a fifth aspect, the invention relates to a computer-readable mediumcomprising instructions which, when executed by a computer, cause the computer tocarry out the method according to the first aspect.

The above-mentioned features and embodiments of the method, the controlarrangement, the vehicle, the computer program, and the computer-readable medium,respectively, may be combined in various possible ways providing further advantageous embodiments.

Further advantageous embodiments of the method, the control arrangement, thevehicle, the computer program, and the computer-readable medium according to thepresent invention and further advantages with the embodiments of the present invention emerge from the detailed description of embodiments.

Brief description of the drawinqsEmbodiments of the invention will be illustrated in more detail below, along with the enclosed drawings, where similar references are used for similar parts, and where: lO Figure1 shows a schematic view illustrating an exemplary vehicle in which embodiments of the present invention may be implemented; Figure 2 shows a flow chart of a method for operating an electrical motor system ofa vehicle according to an embodiment of the invention; Figure 3 illustrates a vehicle driving through a route according to an embodiment of the invention; Figure 4 shows a control arrangement, in which a method according to any one ofthe herein described embodiments may be implemented.

Detailed descriptionAn electrical motor system dimensioned to continuously cope with a high-power and temperature demands will be unnecessary heavy, large, and expensive.

On the other hand, electrical motor system which is not properly dimensioned may notbe able to provide a required power during situations when the power output isthermally limited in some parts of the electrical motor system. lt is an objective of the present invention to provide a method and a controlarrangement for providing a power output from an electrical motor such that these problems are at least partly solved.

Figure 1, which will be used to explain the herein presented embodiments,schematically illustrates a vehicle 100. The vehicle 100 may e.g. be a car, a bus, or atruck. The vehicle 100 illustrated in Figure 1 comprises an electrical motor system 101with at least one electrical motor 102 configured for driving the drive wheels 111, 112of the vehicle 100. ln the shown embodiment, the vehicle 100 comprises two drivingwheels 111, 112 but it should be understood that the vehicle 100 may be arranged withone of more driving wheels. The at least one electrical motor 102 may, as depicted inFigure 1, be connected to a gearbox 104 via an input shaft 106. The vehicle 100 maycomprise a propeller shaft 107 from the gearbox 104 which drives the driving wheels lO lO 111, 112 via a central gear 105, for example a conventional differential, and two driveshafts 108, 109 of the vehicle 100. lt should be understood that the vehicle 100 maybe arranged in any known way, for example without a gearbox 104 or conventional differential without limiting the scope of the invention.

The at least one electrical motor 102 may be arranged essentially anywhere, as longas torque is provided to one or more of the wheels 111, 112, for example adjacent toone or more of the wheels, or in any other conventional way as is understood by askilled person. The at least one electrical motor 102 may be provided with electricalpower from a battery system 103 via a power electronic module 110, both included inthe electrical motor system 101 of the vehicle 100. The battery system 103 may in oneexample comprise an electrical battery unit or a plurality of electrical battery units. lnanother example, the battery system 103 may comprise a fuel cell, possibly incombination with a battery unit. The power electronic module 110 converts the DCvoltage provided by the battery unit to voltage demanded by the electrical motor,typically a three phase AC voltage.

The vehicle 100 may be a pure electrical vehicle and only include electrical motors 102for driving the drive wheels 111, 112 of the vehicle 100. However, the vehicle 100 maybe a so-called hybrid vehicle and also include a combustion engine (not illustrated inFigure 1), for example an internal combustion engine or another combustion engine,which may in a conventional manner by connected to the gearbox 104 via a clutch (notillustrated in Figure 1).

The electrical motor system 101 is controlled by a vehicle control system via a controlarrangement 120. The control arrangement 120 may be distributed on several controlunits configured to control different parts of the vehicle 100. The control arrangement120 may e.g. include a predicting unit 121, a determining unit 122 and an operatingunit 123 arranged for performing the method steps of the disclosed invention as isexplained further on. The control arrangement 120 and/or another control arrangementmay further be configured for controlling any other units/devices/entities of the vehicle100. However, in Figure 1, only the units/devices/entities of the vehicle useful for understanding the present invention are illustrated. The control arrangement 120 will be described in further detail in Figure 4.

The vehicle 100 may further include one or more sensors 130, e.g. at least one camera located at suitable positions within the vehicle 100.

Further, the vehicle 100 may comprise a positioning system/unit 140. The positioningunit 140 may be based on a satellite navigation system such as the Navigation SignalTiming and Ranging (Navstar), Global Positioning System (GPS), Differential GPS(DGPS), Galeo, GLONASS, or the like. Thus, the positioning unit 140 may comprise aGPS receiver.

The vehicle 100 may further include at least one communication device 150 arrangedfor communication with at least one entity 160 external to the vehicle 100, such as atleast one communication entity of another vehicle. Correspondingly, the at least onecommunication device 150 may be a vehicle-to-vehicle (V2V) communication device,a vehicle-to-infrastructure (V2|) communication device, a vehicle-to-everything (V2X)communication device, and/or a wireless communication device such thatcommunication between the vehicle and the at least one external entity 160 isachieved/provided.

The proposed invention will now be described with reference to a method 200,disclosed in Figure 2, for operating an electrical motor system 101 of a vehicle, suchas the vehicle 100 disclosed in Figure 1. The method 200 comprises: ln step 210 in Figure 2 predicting a set of temperature profiles for the electricalmotor system 101 in an upcoming road section 510 based on a set of speed profilesfor the upcoming road section 510 and information associated with the upcoming roadsection 510, wherein each temperature profile in the set of temperature profiles isassociated with a speed profile in the set of speed profiles and an operatingtemperature T of the electrical motor system 101; ln step 220 in Figure 2 determining a power outtake for the electrical motorsystem 101 based on a temperature profile in the set of temperature profiles based onits threshold temperature Th in the upcoming road section 510; and ln step 230 in Figure 2 operating the electrical motor system 101 in the upcoming road section 510 according to the determined power outtake.

As previously explained, the electrical motor system 101 may here comprise at leastone electrical motor 102, a related battery system 103 and a power electronics module110.

The method 200 may be executed when the vehicle 100 is powered by the electricalmotor system 101 and where the tractive and braking force for propulsion and braking of the vehicle is generated by one or more electrical motors 102.

The speed of the vehicle 100 may be controlled automatically by means of a controlarrangement 120 repetitively executing the method steps 210 - 230 based on forinstance information related to the road section in front of the vehicle 100 such that thepower output from the electrical motor system 101 is optimized taking intoconsideration its thermal limitations.

The method 200 and further embodiments of the invention will now be explained inmore detail with reference to Figure 3. Figure 3 illustrates a driving scenario, where theaspect of method 200 illustrated in Figure 2 and further embodiments of the methodmay be implemented. Figure 3 shows a vehicle, such as the vehicle 100 disclosed inFigure 1, driving with a current speed, vc, through a route where 510 refers to anupcoming road section.

As previously explained the speed on the vehicle 100 may be controlled automatically.ln one example, such automatic speed control may be obtained by a cruise controlfunction. The cruise control function may be of kind that uses additional informationwhen controlling the speed of the vehicle. For example, the cruise control can makeuse of a "Look Ahead" function e.g. active prediction function. A "Look Ahead" cruisecontrol (LACC) function consists of a cruise control function that uses knowledgeconcerning the upcoming section 510 of road, i.e., knowledge about the topography ofthe road in front of the vehicle, in order to adapt the vehicle velocity based on variationsin the road along which the vehicle is travelling. ln another example, the speed of the vehicle 100 may be controlled in the vehicle'sdriveline control system executing the logic of steps 210-230 and altering the manualdriver control of the accelerator pedal.

The speed of the vehicle 100 may be controlled by determining at least one speedprofile v1, v2, vn for the upcoming road section 510 as shown in Figure 3. The atleast one speed profile may comprise an expected speed variation of the vehicle 100when vehicle is propelled in the upcoming road section 510. ln other words, one speedprofile may represent one expected speed variation of the vehicle in the upcoming roadsection 510. The expected speed variation may, in conventional manner, depend onthe current speed of the vehicle, vc, speed limitations in the upcoming road section510, traffic conditions, driver preferences just to mention a few relevant parameters.

Driving the vehicle 100 in the upcoming road section 510 according to a speed profile,will require the electrical motor 102 of the vehicle 100 to provide a power, either tractiveor braking, to the vehicle's drive wheel which in each instant corresponds to the speedof the speed profile. The load on the electrical motor system 101 depending on the power variation will thus vary and so will the temperature of its components.

As illustrated in Figure 3, when the vehicle 100 drives with a speed corresponding toone of the speed profiles v1, vz, vn, a load on the electrical motor system 101 andits component will cause a temperature variation in the components of the electricalmotor system 101. The caused temperature variation is exemplified in Figure 3 astemperature profiles T1, Tz, Tn_ Thus each of the at least one speed profiles v1, vz, vn may correspond to a temperature profile, i.e. an expected temperaturedevelopment per time unit T1, T2, Tn in different components of the electrical motorsystem 101 of vehicle 100 when the vehicle's speed corresponds to a speed profile inthe upcoming road section 510. The temperature development may here relate to thetemperature of the components of the electrical motor 102, the power electronic module 110 and the battery system 103 as will be explained further on. ln step 210 in Figure 2 the set of temperature profiles, i.e., the expected temperaturedevelopment per time unit T1, Tz, Tn for the electrical motor system 101 in an upcoming road section 510 is predicted.

Predicting a set of temperature profiles for the electrical motor system 101 in anupcoming road section 510 in step 210 in Figure 2 may comprise determining, for eachspeed profile v1, vz, vn and based on information associated with the upcoming roadsection 510 at least one corresponding temperature variation per time unit T1, Tz, Tn.

The predicted set of temperature profiles T1, Tz, Tn may comprise one or moretemperature profiles where each temperature profile represents a temperaturevariation in one component of the electrical motor system 101. Each temperatureprofile for a specific component may thus represent the temperature of the componentduring the load on the component that arises when the vehicle speed varies accordingto one of the determined speed profiles v1, vz, vn in the upcoming road section 510.

Predicting the set of temperature profiles may here be achieved according toconventional methods based on thermal models of each component representing temperature variation in the component as a function of load on the component.

The load that each of the component needs to cope with during driving according toeach one of the determined speed profiles v1, vz, vn in the upcoming road section510 may be obtained by modelling the vehicle dynamics and/or by extrapolations from measured load values.

As with any modelling, the load on the electrical motor system 101 can be modelledwith various levels of detail which may affect the accuracy of the load predictions. lnother words, predicting the set of temperature profiles in step 210 in Figure 2 may bebased on a number of factors which have an impact on the temperature of thecomponents of the electrical motor system 101 such as road topology, ambienttemperature, various internal energy losses in the vehicle. Some of these factors willnow be further explained.

The set of temperature profiles T1, Tz, Tn for the electrical motor system 101 maybe based on the determined set of speed profiles v1, vz, vn for the upcoming roadsection 510 and information associated with the upcoming road section 510. ln an embodiment, the information associated with the upcoming road section 510 maybe one or more of: topographic data, cartographic data, traffic data and vehicle-to-everything interaction data.

Information associated with the upcoming road section 510 may e.g., comprisetopographic data, such as road inclination and length of uphill and/or downhill sections.Such information may be obtained from digital maps and cartographic in combinationwith positioning information, e.g., global positioning system, GPS, information. Thepositioning information may be used to determine the location of the vehicle relative tothe map data so that the road section information may be extracted from the map data.Various present-day cruise control systems use map data and positioning information.Such systems may then provide the system for the present invention with map dataand positioning information. ln one example, information associated with the upcomingroad section 510 can be received communication from at least one other vehicle. Suchcommunication may e.g., be received by means of V2V communication, V2lcommunication, V2X communication, or similar. ln another example, topographicinformation may be stored in the vehicle and retrieved in combination with positioning information.

Information associated with the upcoming road section may, in yet another example,be obtained in the vehicle by means of onboard sensors and cameras or lidarscollecting information associated with the upcoming road section. The collection ofinformation may e.g. be obtained while the vehicle drives on a road section. Suchcollected information may be stored in the vehicle and used next time the vehicle driveson that particular road section. ln one example also corresponding vehicle data maybe obtained and stored in the vehicle. For example, a temperature of the componentsof the the electrical motor system 101 over a specific road section may be measuredand stored in the vehicle.

Such information may be used when predicting the set of temperature profiles for theelectrical motor system 101 in an upcoming road section 510 in step 210 of method200. Such prediction may thus be done by e.g. self-learning technology in the vehicleusing the resulting temperature profile over a specific road section.

By taking into account the information associated with the upcoming road section 510,when predicting the set of temperature profiles T1, Tz, Tn, an anticipated load onthe electrical motor system 101 of the vehicle 100 may be calculated corresponding toa propulsion force needed to propel the vehicle at a speed according to the set ofspeed profiles v1, v2, vn in the upcoming road section 510. ln case of road inclinationin the upcoming road section 510, the vehicle's dynamics will be affected by a gradingforce. Since the vehicle 100 may be travelling uphill or downhill the grading force mayeither be resisting or contributing to the tractive force of the vehicle 100. During uphilldriving, the grading force will be resisting the vehicle's tractive force adding load on theelectrical motor system 101 and thus causing temperature increase. During downhilldriving, the grading force will contribute to the vehicle's tractive force. However, theuse of the electrical motor system 101 and the driveline of the vehicle 100 forregenerative braking as well as braking of the vehicle 100 which contribute to theresistive force should be taken into account when predicting the temperature profiles.Such calculations may be performed according to conventional methods. For example,by using Newton's laws of motion the propulsion or braking force corresponding to aload on the electrical motor system 101 may be calculated based on parameters likethe vehicle's mass, speed, and the inclination of the road in front of the vehicle tomention a few. The temperature of the components of the electrical motor system 101may be calculated e.g., based on theoretical models of the component's temperatureas a function of the engine load.

Temperature in the components of the electrical motor system 101 may furthermoredepend on various internal losses in the vehicle when a tractive force is exerted fromthe electrical motor to the drive wheels of the vehicle or from the wheels to the enginewhen the electric motor is used as a brake i.e. generator. Those losses may dependon a number of resistive forces acting on the vehicle when the vehicle is in motion, forexample grading force, aerodynamic drag, rolling resistance etc.

Thus, in an embodiment, the predicting 210 the set of temperature profiles may furtherbe based on vehicle configuration data for the vehicle 100. ln one example, predicting 210 the set of temperature profiles may be based on acurrent weight of the vehicle 100. As previously described, the weight of the vehiclemay be used, together with topographic data, to predict the power required from theelectrical motor 102 to propel the vehicle 100 at a certain speed. ln another example, predicting 210 the set of temperature profiles may be based on avehicle model. For instance, the cross-sectional area of the vehicle, which variesdepending on the vehicle size and shape may impact the anticipated load on theelectrical motor system 101 and its components of the vehicle 100 due to the aerodynamic drag that the vehicle is exposed to during driving. ln yet another example, predicting 210 the set of temperature profiles may be basedon further vehicle configuration data, such as the type of gearbox, the configuration of the driveline and an axle and/or type of tires.

The load on the electrical motor system 101 and its components may be impacted bymechanical losses in the gearbox and the driveline, like rolling and sliding losses. Typeof tires, air pressure etc. may affect the vehicle's rolling resistance which maycontribute to the load on the electrical motor system 101.

Vehicle configuration data may be obtained from a configuration file stored in thevehicle or obtained in a conventional way. For example, the air pressure in the vehicle's tires may be obtained from sensor measurements.

Hereby, the temperature profiles may be predicted in a precise manner taking intoconsideration the vehicle configuration data which may impact the thermal characteristics of the electrical motor system.

As previously explained, each temperature profile T1, Tz, Tn in the set oftemperature profiles may be associated with a speed profile in the set of speed profiles v1, vz, vn and an operating temperature T of the electrical motor system 101.

The operating temperature T may here be a temperature of one or more componentsof the electrical motor system 101 that must be kept within a safe operatingtemperature, i.e., below, or substantially below a temperature threshold value Thassociated with the component in order not to decrease the component's lifetime orlead to component failure as will be explained further on.

Thus, each speed profile v1, vz, vn may correspond to one or more temperatureprofiles, wherein each temperature profile may represent a temperature variation inone component of the electrical motor system 101 where due to different lossestemperature may increase and shorten the lifetime of that component or lead to component failure.

According to embodiments the operating temperature T may be one or more of: atemperature of a winding, a temperature of power electronics, a temperature of apermanent magnet of the electrical motor system 101, a temperature of a battery cellin the battery system 103 and a temperature of a battery pack in the battery system103. ln other words the predicting a set of temperature profiles in step 210 in Figure 2 maycomprise predicting one set of temperature profiles per component electrical motorsystem 101, wherein the component may be one of: a temperature of a winding, atemperature of power electronics, a temperature of a permanent magnet of theelectrical motor system 101, a temperature of a battery cell in the battery system 103and a temperature of a battery pack in the battery system 103.

An electrical motor converts electrical energy into mechanical energy. The electricalmotor may operate through an interaction between the motors magnetic field and anelectrical current in a wire winding. High temperatures may degrade the windinginsulation and shorten the lifetime of the wire winding and if high enough cause immediate winding failure. Thus, in one example, each speed profile v1, vz, vn may correspond to a temperature profile of the wire winding in the electrical motor 102.

A permanent magnet motor uses permanent magnets in addition to winding on its field,rather than windings only. High temperature in the permanent magnets may potentiallylead to demagnetization of the permanent magnets and motor failure. Thus, in oneexample, each speed profile v1, vz, vn may correspond to a temperature profile ofthe permanent magnets in the electrical motor 102.

The main losses in the power electronics module 110 may arise due to conduction andswitching in the transistors. Too high temperature may lead to overheating thetransistors, shorten their lifetime or lead to failure. Thus, in one example, each speedprofile v1, v2, vn may correspond to a temperature profile of the transistors in the power electronics module 110. ln addition, also the lifetime of the battery system may decrease when the temperatureof components of the battery system rises above a threshold value. This is especiallyimportant in hybrid vehicles where the battery system is usually smaller compared toa pure electrical vehicle and where a power output from every cell might becomeconsiderable. Thus, in one example, each speed profile v1, v2, vn may correspondto a temperature profile of the battery cell or battery pack in the battery system 103.

As previously described, the temperature in the components of the electrical motorsystem 101 will vary depending on the load on the system, i.e. the power outtake fromthe system and losses in the system. Each component in the electrical motor system101 may be associated with a corresponding power loss profile. A power loss profileof a component comprises a relation between the components temperature variationand the load acting on the component, which in turn may depend on the speed of thevehicle. Predicting 210 the set of temperature profiles further based on a set of powerloss profiles for the electrical motor system 101 in the upcoming road section 510 maygive an accurate prediction of the temperature distribution in the electrical motorsystem 101 at different vehicle speeds.

Thus, in an embodiment, predicting 210 the set of temperature profiles may be furtherbased on a set of power loss profiles for the electrical motor system 101 in theupcoming road section 510.

An electrical motor system 101 in a motor vehicle 100 will operate efficiently and safelywhen its operating temperature T is within its safe operating temperature. A safeoperating temperature is often limited by a temperature threshold value Th asillustrated in Figure 3. The temperature threshold may vary depending on whichcomponent of the motor system is considered. The temperature threshold Th of acomponent or a system may represent a maximum allowed operating temperature ofthe component or the system. When reaching temperatures above the safe operatingtemperature, the wear on the electrical motor system 101 and its components mayincrease which may lead to decreased component lifetime or even to a componentfailure. Moreover, the degree of damage or wear on the component that occurs whenthe temperature threshold of the component is exceeded depends on component type,how much the temperature is exceeded and how long time the temperature isexceeded.

For some components, their temperature threshold Th must never be exceeded, whilefor other components slightly exceeding the temperature threshold Th may be possibleunder limited periods of time. ln some cases, it may even be desirable to temporarilyexceed the temperature threshold Th in order to be able to increase the power outputfrom the electrical motor system 101 and thus the average speed.

T1, illustrated in Figure 3, is a temperature profile corresponding to the speed profile v1exhibiting a temperature variation below the temperature threshold Th. T2 is atemperature profile corresponding to the speed profile v2 exhibiting a temperaturevariation substantially below the temperature threshold Th wherein the temperaturemay momentarily exceed the temperature threshold Th, and Tn is a temperature profilecorresponding to the speed profile vn wherein the temperature variation clearly exceeds the temperature threshold during a non-negligible time period. lO 21 Merely as an illustrative and very simplified example, assume that a component of theelectrical motor system 101 can be operated at temperatures ranging from 1 to 10,where 1-7 corresponds to temperatures where "normal" or expected wear of theelectric component and on the electrical motor system 101. At temperature 8,corresponding to a threshold as is described in this disclosure, the wear of thecomponent increases significantly, even more so at temperature 9 and at temperature10 the component brakes down. Assume further in this simplified and illustrativeexample that a duration of a minute at temperature 8 increases the wear of thecomponent such that its overall lifetime is reduced by 1 %; two minutes results in areduction of overall lifetime by 2.5% and 10 minutes results in breakdown of thecomponent. Likewise, a duration of a minute at temperature 9 increases the wear ofthe component such that its overall lifetime is reduced by 5 %; two minutes results ina reduction of overall lifetime by 15% and 5 minutes results in breakdown of thecomponent. From this very simplified example, it is obvious that it is possible to exceedthe threshold, but it will be at a cost of increased wear and reduced overall lifetime ofthe component. Assume further that the vehicle 100 is being driven uphill and thetemperature increases as the vehicle 100 travels uphill. Assume that just before thetop of the hill, the temperature just reaches 8 so that the vehicle 100 is driven 30seconds at which the temperature is 8. Following the uphill section is a downhill sectionin which the vehicle 100 may coast/freewheel such that the temperature of thecomponent drops below 8 in 15 seconds meaning that the total time of the componentbeing operated at temperature 8 is 45 seconds. This may be considered acceptable,however, what is acceptable may be a matter of definition of either the manufactureror the vehicle operator/owner. However, assume that the vehicle 100 instead ofcoast/freewheel in the following downhill section must use the electric motor brake todecreases the speed leading to even larger temperature increases in the component.Such an increase may not be acceptable and thus another speed profile must bechosen. Alternatively in this simplified example, assume that following the uphill sectionis a straight section wherein it takes 1 minute for the temperature to drop below 8meaning that the total time of the component being operated at temperature 8 is 90seconds. ln this illustrative example, this may be considered too long a time resultingin too much a reduction of the lifetime of the component such that another speed profileis chosen, in which the temperature never reaches 8. lO 22 lt is also noted in this very simplified example that the thresho|d(s) and the amount ofwear over time of a component are determined by the hardware itself and may becontrolled at the manufacture of the component. On the other hand, what is deemed"acceptable wear" due to operating the vehicle 100 such that the thresho|d(s) forincreased wear is present may be either up to the manufacturer of the electrical engineor the buyer of the vehicle 100.

This disclosure does not give exact values of thresho|d(s) and/or acceptable time forpossibly exceeding such thresho|d(s) as that is up for the implementation and for whatis deemed to be acceptable wear and corresponding reduction of lifetime of respectivecomponents. Further, when talking about thresholds in this disclosure, it iscorresponding thresholds at temperature 8 that are intended, i.e. thresho|d(s) at which increased wear of respective component is present. ln one example, several threshold values Th1,...,ThX-1, Thx may be considered in eachcomponent's temperature profile, where the highest threshold value Thx may representa temperature value which must never be exceeded while the lower threshold valuesTh1,...,ThX-1 may represent one or more temperature values which may be exceeded to a certain degree during a limited period of time.

The temperature threshold of a component may be determined based on requirementsrelated to the expected and/or desired lifetime of the component. However, the effectof temperature on the overall lifetime of the system needs to be considered. This maybe done by determining, in the step 220 in Figure 2, a power outtake for the electricalmotor system 101. The determined power outtake for the electrical motor system 101may be based on a temperature profile in the set of temperature profiles based on itsthreshold temperature Th in the upcoming road section 510. The temperature profilein the set of temperature profiles may here be the temperature profile of a limiting component.

The power outtake may be determined by means of an optimization algorithm byselecting a power outtake corresponding to optimized -vehicle speed, least wear on lO 23 the electrical motor system 101 and/or least energy consumption of the vehicle 100.Thus, the optimization algorithm aims at selecting a best available speed profile, fromthe set of speed profiles v1, v2, vn , wherein the selected speed profile correspondsto a power outtake. Each temperature profile associated with the selected speed profilemust fulfill the temperature requirements related to the temperature thresholds of thecorresponding component as described above and the at least one optimizationcriterion. To perform the optimization, the optimization algorithm may translate eachset of temperature profiles into a prediction of component and/or system wear, i.e. howit affects the lifetime of the electrical motor system 101. The speed profile is chosenthat gives an optimized average speed, least wear on the electrical motor system 101and/or least energy consumption while not violating the requirements for minimum ordesired lifetime of the electrical motor system 101. The power outtake is then set accordingly. ln one embodiment each speed profile in the set of speed profiles may have anaverage speed and the determining in step 220 the power outtake for the electricalmotor system 101 may further be based on the average speed of each individual speed profile. ln one example it might be advantageous to determine the power outtake for theelectrical motor system 101 based on a temperature profile corresponding to a speedprofile having the highest average speed in the upcoming road section 510. Thus, inan embodiment the average speed of the speed profile may be the highest averagespeed in the upcoming road section 510. ln another example, it might be advantageous to further determine the power outtakefor the electrical motor system 101 to be a constant power outtake, rather than onecorresponding to the highest average speed to avoid a jerky behavior of the vehicle100. ln an embodiment, determining the power outtake for the electrical motor system 101may take into account the energy consumption of the electrical motor system 101 inthe upcoming road section 510. For example, the power outtake may be based on the lO 24 temperature profile which fulfills the temperature requirement as previously described,and which corresponds to the speed profile requiring the lowest energy consumptionin the electrical motor system 101 when the vehicle 100 is propelled in the upcomingroad section 510 with a speed according to the speed profile.

The energy consumption of the electrical motor system 101 may be determined by theefficiency map of the electrical motor together with and the predicted power outtakeand losses of other components. ln an embodiment, determining the power outtake for the electrical motor system 101may take into account wear on the electrical motor system 101 in the upcoming roadsection 510.

As previously explained the wear on the electrical motor system 101 will increase whenthe temperature of its components exceeds the component's safe operatingtemperature. Thus in one example, the power outtake may be based on thetemperature profile which fulfills the temperature requirement as previously described,and which corresponds to the speed profile causing the lowest wear on the electricalmotor system 101 when the vehicle is propelled in the upcoming road section 510 witha speed according to the speed profile.

By operating the electrical motor system 101 in the upcoming road section 510according to the determined power outtake in step 230 in Figure 2 the electrical motorsystem 101 may be controlled to deliver a power so that the vehicle 100 may bepropelled according to the speed profile corresponding to the selected temperatureprofile.

According to an aspect of the invention, a control arrangement 120 for controlling anelectrical motor system 101 of a vehicle 100 is presented. The control arrangement120 includes means 121 arranged for to predict a set of temperature profiles for theelectrical motor system 101 in an upcoming road section 510 based on a set of speedprofiles for the upcoming road section 510 and information associated with theupcoming road section 510, wherein each temperature profile in the set of temperature lO profiles is associated with a speed profile in the set of speed profiles and an operating temperature T of the electrical motor system 101.

The control arrangement 120 further includes means 122 arranged for determining apower outtake for the electrical motor system 101 based on a temperature profile inthe set of temperature profiles based on its threshold temperature Th in the upcomingroad section 510.

The control arrangement 120 further includes means 123 arranged for operating theelectrical motor system 101 in the upcoming road section 510 according to thedetermined power outtake.

The control arrangement 120, e.g. a device or a control device, according to theinvention may be arranged for performing all of the above, in the claims, and in theherein described embodiments method steps. The control arrangement 120 is herebyprovided with the above-described advantages for each respective embodiment.

The invention is also related to a vehicle 100 including the control arrangement 120.Now turning to Figure 4 which illustrates the control arrangement 600/120, which maycorrespond to or may include one or more of the above-mentioned control units 121 -123 i.e. the control units performing the method steps of the disclosed invention. Thecontrol arrangement 600/120 comprises a computing unit 601, which can beconstituted by essentially any suitable type of processor or microcomputer, e.g. acircuit for digital signal processing (Digital Signal Processor, DSP), or a circuit havinga predetermined specific function (Application Specific Integrated Circuit, ASIC). Thecomputing unit 601 is connected to a memory unit 602 arranged in the controlarrangement 600/120, which memory unit provides the computing unit 601 with, e.g.,the stored program code and/or the stored data which the computing unit 601 requiresto be able to perform computations. The computing unit 601 is also arranged to storepartial or final results of computations in the memory unit 602. ln addition, the control arrangement 600/120 is provided with devices 611, 612, 613,614 for receiving and transmitting input and output signals. These input and output signals can contain waveforms, impulses, or other attributes which, by the devices 611,613 for the reception of input signals, can be detected as information and can beconverted into signals which can be processed by the computing unit 601. Thesesignals are then made available to the computing unit 601. The devices 612, 614 forthe transmission of output signals are arranged to convert signals received from thecomputing unit 601 in order to create output signals by, e.g., modulating the signals,which can be transmitted to other parts of and/or systems in the vehicle 100.

Each of the connections to the devices for receiving and transmitting input and outputsignals can be constituted by one or more of a cable; a data bus, such as a CAN bus(Controller Area Network bus), a MOST bus (Media Orientated Systems Transportbus), or some other bus configuration; or by a wireless connection. A person skilled inthe art will appreciate that the above-stated computer can be constituted by thecomputing unit 601 and that the above- stated memory can be constituted by the memory unit 602.

Control systems in modern vehicles commonly comprise communication bus systemsconsisting of one or more communication buses for linking a number of electroniccontrol units (ECU's), or controllers, and various components located on the vehicle.Such a control system can comprise a large number of control units and theresponsibility for a specific function can be divided amongst more than one control unit.Vehicles of the shown type thus often comprise significantly more control units thanare shown in Figures 1 and 4, which is well known to the person skilled in the art within this technical field. ln a shown embodiment, the invention may be implemented by the one or more abovementioned control units 121, 122 and 123. The invention can also, however, beimplemented wholly or partially in one or more other control units already in the vehicle100, or in some control unit dedicated to the invention.

Here and in this document, units are often described as being arranged for performingsteps of the method according to the invention. This also includes that the units are designed to and/or configured to perform these method steps.

The one or more control units 121, 122 and 123 are in Figure 1 illustrated as separateunits. These units may, however, be Iogically separated but physically implemented inthe same unit or can be both logically and physically arranged together. These unitsmay e.g. correspond to groups of instructions, which can be in the form of programmingcode, that are input into, and are utilized by a processor/computing unit 601 when theunits are active and/or are utilized for performing its method step, respectively.

The person ski||ed in the art will appreciate that the herein described embodiments forcontro||ing an engine may also be implemented in a computer program, which, whenit is executed in a computer, instructs the computer to execute the method. Thecomputer program is usually constituted by a computer program product 603 storedon a non-transitory/non-volatile digital storage medium, in which the computer programis incorporated in the computer-readable medium of the computer program product.The computer-readable medium comprises a suitable memory, such as, e.g.: ROM(Read-Only Memory), PROM (Programmable Read-Only Memory), EPROM (ErasablePROM), Flash memory, EEPROM (Electrically Erasable PROM), a hard disk unit, etc.The invention is not limited to the above-described embodiments. lnstead, theinvention relates to, and encompasses all different embodiments being included withinthe scope of the independent claims.

Claims

1. A method (200) for Operating an electrical motor system (1 01) of a vehicle (100), themethod (200) comprising: predicting (210) a set of temperature profiles for the electrical motor system (101)in an upcoming road section (510) based on a set of speed profiles for the upcomingroad section (510) and information associated with the upcoming road section (510),wherein each temperature profile in the set of temperature profiles is associated witha speed profile in the set of speed profiles and an operating temperature (T) of theelectrical motor system (101); determining (220) a power outtake for the electrical motor system (101) based ona temperature profile in the set of temperature profiles based on its thresholdtemperature (Th) in the upcoming road section (510); and operating (230) the electrical motor system (101) in the upcoming road section(510) according to the determined power outtake.

2. The method (200) according to claim 1, wherein each speed profile in the set ofspeed profiles has an average speed, andwherein determining (220) the power outtake for the electrical motor system (101) is further based on the average speed of each individual speed profile.

3. The method (200) according to claim 2, wherein the average speed of the speedprofile is a highest average speed in the upcoming road section (510).

4. The method (200) according to any of claims 1-3, wherein the determining (220) ofthe power outtake for the electrical motor system (101) takes into account the energy consumption of the electrical motor system (101) in the upcoming road section (510).

5. The method (200) according to any of claims 1-4, wherein the determining (220) ofthe power outtake for the electrical motor system (101 ) takes into account wear on the electrical motor system (101) in the upcoming road section (510).

6. The method (200) according to any one of the preceding claims, further comprising lOpredicting (210) the set of temperature profiles further based on vehicle configuration data for the vehicle (100).

7. The method (200) according to claim 6, wherein the vehicle configuration data isone or more of: a current weight, a vehicle model, a type of gearbox, a drive line configuration, an axle configuration and type of tires.

8. The method (200) according to any one of the preceding claims, wherein theinformation associated with the upcoming road section (510) is one or more of:topographic data, cartographic data, traffic data and vehicle-to-everything interactiondata.

9. The method (200) according to any one of the preceding claims, further comprisingpredicting (210) the set of temperature profiles further based on a set of power lossprofiles for the electrical motor system (101) in the upcoming road section (510).

10. The method (200) according to any one of the preceding claims, wherein theoperating temperature (T) is one or more of: a temperature of a winding, a temperatureof power electronics, a temperature of a permanent magnet of the electrical motorsystem (101), a temperature of a battery cell in the battery system (103) and atemperature of a battery pack in the battery system (103).

11. A control arrangement (120) for controlling an electrical motor system (101) of avehicle (100), the control arrangement (120) being configured to predict a set of temperature profiles for the electrical motor system (101) in anupcoming road section (510) based on a set of speed profiles for the upcoming roadsection (510) and information associated with the upcoming road section (510),wherein each temperature profile in the set of temperature profiles is associated witha speed profile in the set of speed profiles and an operating temperature (T) of theelectrical motor system (101); determine a power outtake for the electrical motor system (101) based on atemperature profile in the set of temperature profiles based on its thresholdtemperature (Th) in the upcoming road section (510); and lO operate the electrical motor system (101) in the upcoming road section (510) according to the determined power outtake.

12. A vehicle (100) comprising a control arrangement (120) according to claim

13. A computer program comprising instructions which, when the program is executedby a computer, cause the computer to carry out the method (200) according to any one of the c|aims 1 to

14. A computer-readabie medium comprising instructions which, when executed by acomputer, cause the computer to carry out the method (200) according to any one of the c|aims 1 to 10.