CONTROLLING ENERGY MANAGEMENT OF A TRACTION BATTERY OF A HYBRID ELECTRIC VEHICLE

Aspects of the present invention relate to a control system 208 and method for controlling energy management of a traction battery 200 of a hybrid electric vehicle 10, the traction battery 200 configured to power at least one traction motor 212 coupled to an electric-only axle 213 of the vehicle 10 to provide all-wheel drive, the control system 208 comprising one or more electronic controllers 300, the one or more electronic controllers 300 configured to: determine a change of terrain mode and/or type for the vehicle and/or determine an increase in loading of the vehicle 10; select an energy management control strategy for the traction battery 200 of the vehicle 10 in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle 10, wherein the traction battery 200 is configured to supply power to the at least one traction motor 212 to provide torque to the electric-only axle 213 of the vehicle 10 to enable the vehicle 10 to operate in an all-wheel drive mode, wherein selecting an energy management control strategy of the vehicle 10 comprises at least one of: selecting or adjusting a charge sustain set point 30 for the traction battery 200; and changing energy generation to recharge the traction battery 200.

TECHNICAL FIELD

The present disclosure relates to controlling energy management of a traction battery. In particular, but not exclusively, it relates to controlling energy management of a traction battery of a hybrid electric vehicle.

BACKGROUND

Hybrid electric vehicles deplete state of charge of one or more traction batteries by driving in electric vehicle mode. Typically, this can continue until a set point is reached in relation to the battery state of charge at which the vehicle enters a different mode of operation in which the state of charge of the traction battery is maintained. In this mode, transient power requirements will sometimes deplete the battery below the set point temporarily. This can result in the state of charge of the traction battery oscillating around the set point due to the transient power requirements.

Thresholds for the battery state of charge can also be implemented to, for example, inhibit all electric vehicle driving and also inhibit all boost and torque fill from a traction motor.

In some driving scenarios particularly high energy usage is required, for example off-road driving.

If energy management of the traction batteries of the vehicle is not carefully controlled there can be insufficient charge to provide required torque from one or more traction motors.

SUMMARY OF THE INVENTION

It is an aim of the present invention to address one or more of the disadvantages associated with the prior art.

Aspects and embodiments of the invention provide a control system, a system, a vehicle, a method, and computer software, as claimed in the appended claims.

According to an aspect of the invention there is provided a control system for controlling energy management of a traction battery of a hybrid electric vehicle, the traction battery configured to power at least one traction motor coupled to an electric-only axle of the vehicle to provide all-wheel drive, the control system comprising one or more electronic controllers, the one or more electronic controllers configured to: determine a change of terrain mode and/or type for the vehicle and/or determine an increase in loading of the vehicle; select an energy management control strategy for the traction battery of the vehicle in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle, wherein the traction battery is configured to supply power to the at least one traction motor to provide torque to the electric-only axle of the vehicle to enable the vehicle to operate in an all-wheel drive mode, wherein selecting an energy management control strategy of the vehicle comprises at least one of: selecting or adjusting a charge sustain set point for the traction battery; and changing energy generation to recharge the traction battery.

An advantage provided is it can be ensured that all-wheel drive is available in a vehicle where needed. For example, it can be ensured that all-wheel drive is available to a vehicle when needed for off-road driving

The one or more electronic controllers may collectively comprise: at least one electronic processor having an electrical input for receiving information associated with a terrain mode and/or type for the vehicle and/or determining an increase in loading of the vehicle; and at least one electronic memory device electrically coupled to the at least one electronic processor and having instructions stored therein; and wherein the at least one electronic processor is configured to access the at least one memory device and execute the instructions thereon so as to cause the control system to determine a change of terrain mode and/or type for the vehicle and/or determine an increase in loading of the vehicle and to select the energy management control strategy of the vehicle.

Determining a change of terrain type may comprise determining the characteristics and/or type of surface that the vehicle is currently being driven on. Determining a change of terrain mode may comprise receiving at least one input from a user of the vehicle selecting a terrain mode of the vehicle. Determining a change of terrain mode and/or type may comprise receiving information from one or more sensors and processing the received information to determine the current terrain mode and/or type of the vehicle.

Determining an increase in loading of the vehicle may comprise determining that the vehicle is experiencing an increase in drag associated with at least one of: driving over a deformable surface, traversing a water crossing and/or towing. Determining an increase in loading of the vehicle may comprise receiving at least one input from a user of the vehicle indicating an increase in loading of the vehicle. Determining an increase in loading of the vehicle may comprise receiving information from one or more sensors and processing the received information to determine an increase in loading of the vehicle.

Selecting or adjusting a charge sustain set point of the traction battery may comprise increasing the charge sustain set point of the traction battery in dependence on the current terrain type and/or loading of the vehicle.

The charge sustain set point may be selected in dependence on the expected increased power demands from driving in a current terrain mode and/or on a current terrain type and/or with the determined increased loading. The charge sustain set point may be selected in dependence on expected manoeuvres at an expected repetition rate for the current terrain mode and/or type.

Selecting or adjusting a charge sustain set point may comprise setting the charge sustain set point at a prevailing battery charge when the terrain mode and/or type and/or the loading of the vehicle is changed.

Changing energy generation to recharge the traction battery may comprise increasing torque provided by an engine of the vehicle to increase electrical energy generation, to supply electrical energy to the traction battery. Changing energy generation to recharge the traction battery may comprise prioritising discharging the battery to meet driving demands over charging the battery.

Electrical energy generation using the engine of the vehicle may comprise electrical energy generation by a belt integrated starter generator and/or a crank integrated motor generator coupled to the engine.

According to an aspect of the invention there is provided a system comprising the control system and an engine configured to power a first axle, at least one traction motor configured to power a second axle, and a traction battery configured to supply power to the at least one traction motor, wherein the engine is configured to drive a generator to charge the traction battery.

According to an aspect of the invention there is provided a vehicle comprising the control system and/or the system.

According to an aspect of the invention there is provided a method for controlling energy management of a traction battery of a hybrid electric vehicle, the traction battery configured to power at least one traction motor coupled to an electric-only axle of the vehicle to provide all-wheel drive, the method comprising: determining a change of terrain mode and/or type for the vehicle and/or determining an increase in loading of the vehicle; selecting an energy management control strategy for the traction battery of the vehicle in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle, wherein the traction battery is configured to supply power to the at least one traction motor to provide torque to the electric only axle of the vehicle to enable the vehicle to operate in an all-wheel drive mode, wherein selecting an energy management control strategy of the vehicle comprises at least one of: selecting or adjusting a charge sustain set point for the traction battery; and changing energy generation to recharge the traction battery.

Determining a change of terrain mode may comprise receiving at least one input from a user of the vehicle selecting a terrain mode of the vehicle. Determining an increase in loading of the vehicle may comprise determining that the vehicle is experiencing an increase in drag associated with at least one of: driving over a deformable surface, traversing a water crossing and/or towing.

Selecting or adjusting a charge sustain set point of the traction battery may comprise increasing the charge sustain set point of the traction battery in dependence on the current terrain type and/or loading of the vehicle.

The charge sustain set point may be selected in dependence on the expected increased power demands from driving in a current terrain mode and/or on a current terrain type and/or with the determined increased loading.

The charge sustain set point may be selected in dependence on expected manoeuvres at an expected repetition rate for the current terrain mode and/or type. Selecting or adjusting a charge sustain set point may comprise setting the charge sustain set point at a prevailing battery charge when the terrain mode and/or type and/or the loading of the vehicle is changed.

Changing energy generation to recharge the traction battery may comprise increasing torque provided by an engine of the vehicle to increase electrical energy generation, to supply energy to the traction battery.

According to an aspect of the invention there is provided a non-transitory computer readable medium comprising computer readable instructions that, when executed by a processor, cause performance of at least one or more methods described herein.

DETAILED DESCRIPTION

Examples of the present disclosure relate to controlling energy management of a traction battery of a hybrid electric vehicle.

In some examples, the vehicle has at least two axles, a traction battery, a traction motor, an electrical generator/motor/machine and an internal combustion engine. In examples, the electrical generator is powered by the internal combustion engine and is arranged to supply electrical power to the traction battery, which is arranged to store electrical energy and to power the traction motor. Each axle is connected to at least one ground engaging wheel and tyre. In some examples, each axle has a pair of ground engaging wheels and tyres. In examples, one of the axles is powered, at least in part, by torque supplied by the internal combustion engine and one of the axles is powered by torque supplied by the traction motor. The axle powered by torque supplied by the traction motor is thus an electric-only powered axle. The vehicle may be driven by torque supplied by the internal combustion engine alone in a single-axle drive configuration. Additionally, or alternatively, the vehicle may be driven by one axle powered by the internal combustion engine and one axle powered by the traction motor in a two-axle configuration.

In examples, the traction battery is configured to power at least one traction motor coupled to an electric-only axle of the vehicle to provide all-wheel drive. Accordingly, in examples, controlling energy management of a traction battery of a hybrid electric vehicle can be considered controlling availability of all-wheel drive in the hybrid electric vehicle.

Controlling energy management of a traction battery of a hybrid electric vehicle as described herein is advantageous as, for example, it can ensure that all-wheel drive is available in a vehicle where needed. For example, it can ensure all-wheel drive is available to a vehicle when needed for off-road driving or driving on slippery and/or deformable surfaces.

FIG.1illustrates an example of a vehicle10in which embodiments of the invention can be implemented. In some, but not necessarily all examples, the vehicle10is a passenger vehicle, also referred to as a passenger car or as an automobile. In other examples, embodiments of the invention can be implemented for other applications, such as industrial vehicles.

The vehicle10is a hybrid electric vehicle (HEV). If the vehicle10is an HEV, the vehicle10may be a full HEV or a mild HEV. Mild HEVs do not have an electric-only mode of propulsion, but an electric traction motor may be configured to provide torque assistance. Full HEVs have an electric-only mode of propulsion.

If the vehicle10is an HEV, the vehicle10may be configured to operate as a parallel HEV. Parallel HEVs comprise a torque path between the engine and at least one vehicle wheel, as well as a torque path between an electric traction motor and at least one vehicle wheel. The torque path(s) may be disconnectable by a torque path connector such as a clutch or transmission. Typically, parallel HEVs differ from series HEVs, because in series HEVs the purpose of the engine is to generate electrical energy and there is no torque path between the engine and vehicle wheels.

In the example ofFIG.1, the vehicle10comprises a control system208. The control system208is configured to operate as described herein. Accordingly,FIG.1illustrates a vehicle10comprising a control system208as described herein.

FIG.2illustrates an example system20for an HEV10. The system20defines, at least in part, a powertrain of the HEV. The system20comprises a control system208. The control system208comprises one or more controllers. The control system208may comprise one or more of: a hybrid powertrain control module; an engine control unit; a transmission control unit; a traction battery management system; and/or the like.

In examples, the control system208provides means to control operation, at least in part, directly or indirectly, of the elements illustrated inFIG.2.

The system20comprises at least two torque sources. A torque source refers to a prime mover, such as an engine, an electric machine, or the like. An electric machine is also referred to herein as an electric traction motor or traction motor. The illustrated system20comprises an engine202. The engine202is an internal combustion engine (ICE). The illustrated engine202comprises three combustion chambers, however a different number of combustion chambers may be provided in other examples.

The engine202is operably coupled to the control system208to enable the control system208to control output torque of the engine202. The output torque of the engine202may be controlled by controlling one or more of: air-fuel ratio; spark timing; poppet valve lift; poppet valve timing; throttle opening position; fuel pressure; turbocharger boost pressure; and/or the like, depending on the type of engine202.

The system20comprises a transmission204for receiving output torque from the engine202. The transmission204may comprise an automatic vehicle transmission, a manual vehicle transmission, or a semi-automatic vehicle transmission. The transmission204may comprise one or more friction clutches218and/or a torque converter217between the engine202and a gear train204a. The gear train204ais configured to provide a selected gear reduction in accordance with a selected gear of the vehicle10. The gear train204amay comprise five or more different selectable gear reductions. The gear train204amay comprise at least one reverse gear and a neutral gear.

The system20may comprise a differential204bwhich is a second gear train for receiving output torque from the gear train204a. The differential204bmay be integrated into the transmission204as a transaxle, or provided separately.

The engine202is mechanically connected (coupled) or connectable (couplable) to a first set of vehicle wheels (FL, FR) via a torque path220. The torque path220extends from an output of the engine202to the transmission204, then and then to first set of vehicle wheels (FL, FR) via a first axle or axles222a,222b. In a vehicle overrun and/or friction braking situation, torque may flow from the first set of vehicle wheels (FL, FR) to the engine202. Torque flow towards the first set of vehicle wheels (FL, FR) is positive torque, and torque flow from the first set of vehicle wheels (FL, FR) is negative torque.

The illustrated first set of vehicle wheels (FL, FR) comprises front wheels, and the axles222a,222bare front transverse axles. Therefore, the system20is configured for front wheel drive by the engine202. In another example, the first set of vehicle wheels comprises rear wheels (RL, RR). The illustrated first set of vehicle wheels (FL, FR) is a pair of vehicle wheels, however a different number of vehicle wheels and axles could be provided in other examples.

As illustrated inFIG.2, axles222a,222blinking the first set of wheels FL, FR, together form a front axle assembly of the vehicle10.

In the illustrated system20, no longitudinal (centre) driveshaft is provided, to make room for hybrid vehicle components. Therefore, the engine202is not connectable to a second set of rear wheels (rear wheels RL, RR in the illustration). The engine202may be transverse mounted to save space. In some examples, the engine202is configured to drive the rear wheels but not the front wheels.

A torque path connector218such as a clutch may be provided inside and/or outside a bell housing of the transmission204. The clutch218is configured to connect and configured to disconnect the torque path220between the engine202and the first set of vehicle wheels (FL, FR). The system20may be configured to automatically actuate the clutch218without user intervention.

The system20comprises a first electric motor216. The first electric motor216may be an alternating current induction motor or a permanent magnet motor, or another type of motor. The first electric motor216is located to the engine side of the clutch218.

The first electric motor216may be mechanically connected (coupled) or connectable (couplable) to the engine202via a belt or chain. In examples, the first electric motor216is a belt integrated starter generator. The first electric motor216and the engine202together form a torque source for the first set of vehicle wheels (FL, FR). In the illustration, the first electric motor216is located at an accessory drive end of the engine202, opposite a vehicle transmission end of the engine202. In an alternative example, the first electric motor216is a crankshaft integrated motor generator (also known as a crank integrated starter generator), located at a vehicle transmission end of the engine202.

The first electric motor216is configured to apply positive torque and configured to apply negative torque to a crankshaft (not shown) of the engine202, for example to provide functions such as: boosting output torque of the engine202; facilitating the deactivation (shutting off) of the engine202while at a stop or coasting; activating (starting) the engine202; and/or regenerative braking in a regeneration mode. In a hybrid electric vehicle mode, the engine202and first electric motor216may both be operable to supply positive torque simultaneously to boost output torque. The first electric motor216may be incapable of sustained electric-only driving. In an alternative example, the first electric motor216is not controllable to provide positive torque other than to start the engine202. In an alternative example, the first electric motor216is a crankshaft integrated motor generator, located at a vehicle transmission end of the engine202.

When the torque path220between the engine202and the first set of vehicle wheels (FL, FR) is disconnected, the torque path220between the first electric motor216and the first set of vehicle wheels (FL, FR) is also disconnected.

FIG.2illustrates a second electric motor212, which can be considered an electric traction motor212, configured to enable at least an electric vehicle mode comprising electric-only driving. Another term for the second electric traction motor212is an electric drive unit212or traction motor212. In some, but not necessarily all examples, a nominal maximum torque of the second electric traction motor212is greater than a nominal maximum torque of the first electric motor216.

Even if the torque path220between the engine202and the first set of vehicle wheels (FL, FR) is disconnected, the vehicle10can be driven in electric vehicle mode because the second electric traction motor212is mechanically connected to at least one vehicle wheel.

The illustrated second electric traction motor212is configured to provide torque to the illustrated second set of vehicle wheels (RL, RR). The second set of vehicle wheels (RL, RR) comprises vehicle wheels not from the first set of vehicle wheels (FL, FR). The illustrated second set of vehicle wheels (RL, RR) comprises rear wheels, and the second electric traction motor212is operable to provide torque to the rear wheels RL, RR via a second, rear transverse axle or axles224a,224b. Therefore, the illustrated vehicle10is rear wheel driven in electric vehicle mode. In an alternative example, the second set of vehicle wheels comprises at least one vehicle wheel of the first set of vehicle wheels. In a further alternative implementation, the second electric traction motor212is replaced with two electric traction motors, one for each rear vehicle wheel RL, RR.

The control system208may be configured to disconnect the torque path220between the engine202and the first set of vehicle wheels (FL, FR) in electric vehicle mode, to reduce parasitic pumping energy losses. For example, the clutch218may be opened. In the example ofFIG.2, this means that the first electric motor216will also be disconnected from the first set of vehicle wheels (FL, FR).

Another benefit of the second electric traction motor212is that the second electric traction motor212may also be configured to be operable in a hybrid electric vehicle mode, to enable multi-axle drive (e.g. all-wheel drive) operation despite the absence of a centre driveshaft.

In order to store electrical power for the electric traction motors, the system20comprises an electrical energy storage means such as a traction battery200. The traction battery200provides a nominal voltage required by electrical power users such as the electric traction motors.

The traction battery200may be a high voltage battery. High voltage traction batteries provide nominal voltages in the hundreds of volts. The traction battery200may have a voltage and capacity to support electric only driving for sustained distances. The traction battery200may have a capacity of several kilowatt-hours, to maximise range. The capacity may be in the tens of kilowatt-hours, or even over a hundred kilowatt-hours.

Although the traction battery200is illustrated as one entity, the function of the traction battery200could be implemented using a plurality of small traction batteries in different locations on the vehicle10.

The first electric motor216and second electric traction motor212may be configured to receive electrical energy from the same traction battery200as shown. The electrical coupling of the first electric motor216and the second electric traction motor212to a same traction battery200enables the vehicle10to operate in both parallel and series HEV modes. In series HEV mode, the first electric motor216is configured to generate electrical energy from the engine202while the torque path220is disconnected. The electrical energy is provided to the second electric traction motor212. In parallel HEV mode, the engine202drives the first set of wheels FL, FR and the second electric traction motor212drives the second set of wheels RL, RR.

The illustrated system20comprises inverters. Two inverters210,214are shown, one for each electric traction motor. In other examples, one inverter or more than two inverters could be provided.

The control system208may be configured to determine a change of terrain mode and/or type for the vehicle10and/or determine an increase in loading of the vehicle10.

As used herein, loading of the vehicle can be understood to mean the load experienced by the vehicle10when the vehicle10is driving. In examples loading of the vehicle can result from environmental factors, such as driving over a deformable surface or through water and/or weight factors such as when the vehicle is towing a trailer or another vehicle. Such an increase in the loading of the vehicle generally results in a requirement for more power to be sent to the wheels in order to maintain vehicle speed.

In examples an increase in loading of the vehicle10can increase the drag experienced by the vehicle10when driving, resulting in a general increase in requirement for all-wheel drive and/or increased specific requirement for all-wheel drive resulting from the terrain or surface being driven on.

The control system208may be configured to select an energy management control strategy for the traction battery200of the vehicle10in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle10.

In examples, selecting an energy management control strategy of the vehicle comprises at least on of: selecting or adjusting a charge sustain set point30for the traction battery200; and changing energy/power generation to recharge the traction battery200. See, for example,FIG.6.

Accordingly,FIG.2illustrates a control system208for controlling energy management of a traction battery200of a hybrid electric vehicle10, the traction battery200configured to power at least one traction motor212coupled to an electric-only axle213of the vehicle10to provide all-wheel drive, the control system208comprising one or more electronic controller300, the one or more electronic controller configured to:

determine a change of terrain mode and/or type for the vehicle10and/or determine an increase in loading of the vehicle10;
select an energy management control strategy for the traction battery200of the vehicle10in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle10, wherein the traction battery200is configured to supply power to the at least one traction motor212to provide torque to the electric-only axle213of the vehicle10to enable the vehicle10to operate in an all-wheel drive mode, wherein selecting an energy management control strategy of the vehicle10comprises at least one of: selecting or adjusting a charge sustain set point30for the traction battery200; and changing energy generation to recharge the traction battery200.

In examples changing energy generation to recharge the traction battery200can comprise or be changing electrical power generation.

FIG.2also illustrates a system20comprising a control system208as described herein and an engine202configured to power a first axle, at least one traction motor212configured to power a second axle, and a traction battery200configured to supply power to the at least one traction motor212, wherein the engine202is configured to drive a generator to charge the traction battery200.

In the example ofFIG.2, the system20comprises further systems209. In examples, the further system209can be considered one or more vehicle systems209or one more further vehicle systems209.

In examples, the one or more vehicle systems209are any suitable vehicle system(s)209of the vehicle10. For example, the one or more vehicle systems209may comprise any suitable vehicle system209of the vehicle10controllable, at least in part, directly or indirectly by the control system208.

Additionally, or alternatively, the one or more vehicle systems209may comprise any suitable vehicle system(s)209of the vehicle10from which the control system208can receive one or more signals, for example, one or more signals comprising information.

In some examples, the one or more vehicle systems209may be considered to be further vehicle system(s) 209 separate from, but controlled at least in part by, the control system2019. For example, the one or more vehicle system209can comprise one or more user interfaces and/or one or more transceivers via which user input can be received. Any suitable user interfaces can be used. Any suitable transceivers and/or transmitter(s) and/or receiver(s) can be used.

In some examples, the one or more vehicle systems209comprise one or more sensors. For example, one or more sensors configured to provide information to the control system208to allow a determination of the characteristics and/or type of surface that the vehicle10is currently being driven on.

FIG.2also illustrates a vehicle10comprising the control system208as described herein and/or the system20as described herein.

The system20ofFIG.2may comprise any number of additional elements not illustrated in the example ofFIG.2. Additionally, or alternatively, one or more elements of the system20illustrated in the example ofFIG.2may be integrated and/or combined. In an alternative implementation(s), the vehicle10may be other than shown inFIG.2. In some examples, the vehicle10may be arranged such that the front wheels FL, FR are driven by one or more traction motors and the internal combustion engine is arranged to send torque to the rear axle via the transmission, such that the rear wheels RL, RR are driven, at least in part, by the internal combustion engine.

In some examples, one or more of the elements illustrated in the example ofFIG.2may be omitted from the system20.

FIG.3Aillustrates how the control system208may be implemented. The control system208ofFIG.3Aillustrates a controller300. In other examples, the control system208may comprise a plurality of controllers300on-board and/or off-board the vehicle10.

In examples any suitable control system208can be used.

The controller300ofFIG.3Aincludes at least one processor302; and at least one memory device304electrically coupled to the electronic processor302and having instructions306(e.g. a computer program) stored therein, the at least one memory device304and the instructions306configured to, with the at least one processor302, cause any one or more of the methods described herein to be performed.

FIG.3Atherefore illustrates a control system208, wherein the one or more electronic controllers300collectively comprise: at least one electronic processor (302) having an electrical input for receiving information associated with a terrain mode and/or type for the vehicle and/or determining an increase in loading of the vehicle; and at least one electronic memory device (304) electrically coupled to the at least one electronic processor (302) and having instructions (306) stored therein; and wherein the at least one electronic processor (302) is configured to access the at least one memory device (304) and execute the instructions thereon so as to cause the control system (208) to determine a change of terrain mode and/or type for the vehicle and/or determine an increase in loading of the vehicle and to select the energy management control strategy of the vehicle10.

Accordingly,FIG.3Billustrates a non-transitory computer readable medium308comprising computer readable instructions306that, when executed by a processor (302), cause performance of at least the method of one or more ofFIGS.4and5and/or as described herein.

FIG.4illustrates an example of a method400.

The method400is for controlling energy management of a traction battery200of a hybrid electric vehicle10, the traction battery200configured to power at least one traction motor212coupled to an electric-only axle213of the vehicle10to provide all-wheel drive.

In examples, the method400is performed by the control system208ofFIGS.2and/or3A,3Bor a system20ofFIG.2.

That is, in examples, the control system208described herein comprises means for performing the method400. However, any suitable means may be used to perform the method400.

In examples, the method400can be considered a computer implemented method400for a vehicle10, the method400comprising at least: determining a change of terrain mode and/or type for the vehicle10and/or determining an increase in loading of the vehicle10; selecting an energy management control strategy for the traction battery200of the vehicle10in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle10, wherein the traction battery200is configured to supply power to the at least one traction motor212to provide torque to the electric-only axle213of the vehicle10to enable the vehicle10to operate in an all-wheel drive mode, wherein selecting an energy management control strategy of the vehicle10comprises at least one of: selecting or adjusting a charge sustain set point30for the traction battery200; and changing energy generation to recharge the traction battery200.

At block402, the method400comprises determining change of terrain mode and/or type for the vehicle10and/or determining an increase in loading of the vehicle10.

Terrain types can include one or more of: tarmacadam, concrete, asphalt, paved, gravel of various grade mixture and compaction, snow, ice, sand, grass, rocks, boulders, earth, mud, water of various depths and so on.

Any suitable method for determining a change of terrain mode and/or type for the vehicle10and/or determining an increase in loading of the vehicle10can be used.

In examples a terrain mode is an operating mode of the vehicle10. A vehicle operating mode may be selectable manually, semi-automatically, or automatically.

A change in terrain mode/operating mode of the vehicle can affect and/or change and/or alter one or more settings and/or characteristics of one or more elements of the vehicle10. For example, a change in terrain mode/operating mode can affect and/or change and/or alter one or more elements of the system20illustrated in the example ofFIG.2.

In examples a change in terrain mode/operating mode can affect a plurality of different systems of the vehicle10to change, alter and/or affect the set-up of the vehicle10.

In examples, determining a change of terrain type comprises determining the characteristics and/or type of surface that the vehicle10is currently being driven on.

Determining the characteristics and/or type of surface that the vehicle10is currently being driven on can be done using any suitable method. In examples, determining characteristics and/or type of surface that the vehicle10is currently being driven on comprises monitoring any of the following vehicle parameters: wheel slip; wheel articulation; ride height; road roughness; tyre drag (for example rotational drag of a tyre in contact with the prevailing surface over which the vehicle10is travelling); vehicle speed; vehicle acceleration in any of longitudinal, lateral and/or vertical directions; pitch, roll and/or yaw of the vehicle, which may be measured as an angle and/or angular rate; current gear selection; steering angle; steering rate; and/or a measured difference in rotational speeds between the front and rear tyres.

For example, the characteristics and/or type of surface that the vehicle10is currently being driven on can be determined by receiving and/or processing one or more signals comprising information.

In examples, signals can be received from one or more sensors to enable a determination of the characteristics and/or type of the surface that the vehicle10is currently being driven on. See, for example,FIG.2.

For example, the prevailing surface that the vehicle10is being driven on may be determined, at least in part, by vehicle sensors arranged to monitor the area surrounding the vehicle. In examples, the surface and terrain ahead of the vehicle10can be characterized by means of radar and/or lidar signatures and/or camera-based technologies that make use of computer learning algorithms to associate certain visual characteristics of the scene ahead of the vehicle with subsequent vehicle behaviour.

Characteristics of the surface that the vehicle10is being driven on can include one or more of: surface friction, surface roughness such as undulations, surface texture such as ruts, holes, deformability which will affect wheel drag, changes in gradient, step changes in height, changes in pitch within the spacing between vehicle axles and so on.

In some examples, determining a change of terrain mode comprises receiving at least one input from a user of the vehicle10selecting a terrain mode of the vehicle10. Any suitable method for receiving at least one input from a user of the vehicle selecting a terrain mode of the vehicle10can be used.

In examples, the user can make one or more inputs using any suitable user interface, such as one or more user interfaces of the one or more vehicle systems209ofFIG.2.

For example, a user may use one or more user interfaces ofFIG.2to select a terrain mode of the vehicle10.

Additionally, or alternatively a user can make one or more inputs via a personal device of the user, such as a mobile phone, computer and so on.

In some examples, determining a change of terrain mode and/or type comprises receiving information from one or more sensors and processing the received information to determine a current terrain mode and/or type of the vehicle10.

For example, the one or more sensors ofFIG.2can be configured to provide one or more signals comprising information to the control system208to enable the control system208to determine the current terrain mode and/or type of vehicle.

Any suitable method for determining an increase in loading of the vehicle10can be used.

In examples, determining an increase in loading of the vehicle10can comprise determining that the vehicle10is experiencing an increase in drag associated with at least one of: driving over a deformable surface, traversing a water crossing and/or towing.

In such examples, a deformable surface can be any deformable surface that the vehicle10may drive over resulting in an increase in drag, for example, sand, gravel, snow, mud and so on.

In some examples, determining an increase in loading of the vehicle10comprises receiving at least one input from a user of the vehicle10indicating an increase in loading of the vehicle10.

Any suitable method for receiving at least one input from a user of the vehicle indicating an increase in loading of the vehicle10can be used.

In examples, the user can make one or more inputs using any suitable user interface, such as one or more user interfaces of the one or more vehicle systems209ofFIG.2.

For example, a user may use one or more user interfaces ofFIG.2to indicate an increase in loading of the vehicle10.

Additionally, or alternatively a user can make one or more inputs via a personal device of the user, such as a mobile phone, computer and so on.

In some examples, determining an increase in loading of the vehicle10comprises receiving information from one or more sensors and processing the received information to determine an increase in loading of the vehicle10.

For example, the one or more sensors ofFIG.2can be configured to provide one or more signals comprising information to the control system208to enable the control system208to determine an increase in loading of the vehicle10.

At block404the method400comprises selecting an energy management control strategy for the traction battery200of the vehicle10in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle10, wherein the traction battery200is configured to supply power to the at least one traction motor212to provide torque to the electric-only axle213of the vehicle10to enable the vehicle10to operate in an all-wheel drive mode. In examples, selecting an energy management control strategy for the traction battery200of the vehicle10can be considered and/or can comprise altering and/or controlling an energy management control strategy for the traction battery200of the vehicle10in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle10.

In examples, selecting an energy management control strategy of the vehicle comprises at least one of: selecting or adjusting a charge sustain set point30for the traction battery200; and changing energy generation to recharge the traction battery200. In examples selecting or adjusting a charge sustain set point30for the traction battery200can be considered and/or can comprise changing a charge sustain set point30for the traction battery200.

In examples a charge sustain set point can be considered a pre-determined or variable level of the traction battery state of charge, which the control system208uses as a target around which the traction battery state of charge can vary and to which it tends.

Any suitable method for selecting an energy management control strategy for the traction battery200of the vehicle10in dependence on the determined change in terrain mode and/or type and/or the determined increase in loading of the vehicle10can be used.

In some examples, selecting or adjusting a charge sustain set point30of the traction battery200comprises increasing the charge sustain set point30of the traction battery200in dependence on the current terrain type and/or loading of the vehicle10.

For example, the charge sustain set point30can be increased in dependence on expected increased requirement for all-wheel drive due to the current terrain mode and/or type and/or loading of the vehicle10.

In some examples, the charge sustain set point is selected in dependence on the expected increase in electrical power demands from driving in a current terrain mode and/or on a current terrain type and/or with the determined increased loading.

For example, the charge sustain set point can be selected in dependence on the expected requirement for provision of all-wheel drive in a current terrain mode and/or on a current terrain type and/or due to the loading of the vehicle10.

In some examples, the charge sustain set point is selected in dependence on expected manoeuvres at an expected repetition rate for the current terrain mode and/or type.

For example, the charge sustain set point30can be selected in dependence on an expected requirement of torque to be provided by the traction motor212to provide all-wheel drive for the vehicle10due to the current terrain mode and/or type.

Any suitable method for determining an expected repetition rate for a terrain mode and/or type can be used. In examples, the driving manoeuvres and cycles that will be needed for a predetermined level of vehicle performance in a particular environment can be determined. This can be determined using computer aided simulation and/or test data and can be expressed as a torque requirement versus time.

For example, a vehicle can be driven on a particular off-road route that represents the most demanding driving that the vehicle will be expected to perform. The wheel torque of an optimally capable system can be measured throughout the route. In examples, differences between the vehicle from which the data was taken and a vehicle that is being designed can be taken account of in one or more simulations.

In examples, selecting or adjusting a charge sustain set point30comprises setting the charge sustain set point30at a prevailing battery charge when the terrain mode and/or type and/or the loading of the vehicle is changed.

In examples, the charge sustain set point can be changed for any suitable period of time. In some examples, the charge sustain set point30can be changed until the terrain mode and/or type has changed and/or the vehicle loading is reduced.

In examples, energy generation to recharge the traction battery200can be changed in any suitable way. For example, changing energy generation to recharge the traction battery200can comprise changing the amount of electrical energy supplied to and/or from the traction battery200.

In some examples, energy generation to recharge the traction battery200can be increased in dependence on the determined change of terrain mode and/or type of the vehicle and/or determined increased loading of the vehicle10in view of expected increase torque demands and/or increased requirement for all-wheel drive from the traction motor212of the vehicle10.

In some examples, changing energy generation to recharge the traction battery200comprises increasing torque provided by an engine202of the vehicle10to increase electrical energy generation, to supply electrical energy/power to the traction battery200.

In examples, the engine202of the system20ofFIG.2is be used to charge the traction battery200.

In some examples, changing energy generation to recharge the traction battery200comprises prioritising discharging the battery200to meet driving demands over charging the battery200.

That is, in some examples discharging the battery200can be prioritised in order to ensure that the vehicle10can provide all-wheel drive as needed for the vehicle10to drive in the current terrain mode and/or negotiate the prevailing surface type and/or drive with the current loading of the vehicle10.

Electrical energy generation using the engine202of the vehicle10can be done in any suitable way and using any suitable method.

In some examples, electrical energy generation using the engine202of the vehicle10comprises electrical energy generation via a belt integrated starter generator (BISG) and/or crank integrated motor generator (CIMG) coupled to the engine202. See, for example,FIG.2

A technical effect of the method400is that the vehicle10is able to provide all-wheel drive as required on different driving surfaces and/or with increased loading by having sufficient state of charge of the traction battery200to supply the traction motor212so as to provide torque to the electrically driven axle213.

Additionally, as the vehicle10does not change the energy control strategy for all driving modes and/or types and/or vehicle loading the vehicle10can still, for example, maximise efficiency benefits from allowing a wider range of battery energy to be used in, for example, normal road driving.

FIG.5illustrates an example of a method500.

The method500is for controlling energy management of a traction battery200of a hybrid electric vehicle10, the traction battery200configured to power at least one traction motor212coupled to an electric-only axle213of the vehicle10to provide all-wheel drive.

In examples, the method500is performed by the control system208ofFIGS.2and/or3A,3Bor a system20ofFIG.2.

The example ofFIG.5can be considered to illustrate an example of control behaviour of the control system208.

The method500starts at block501and proceeds to decision block502in which it is determined if the driving mode of the vehicle10is set for an off-road surface with potential of high electric traction demands from the traction motor212.

If the answer is no at block502, the method proceeds to decision block514where it is determined if the traction battery200state of charge is above a pre-set minimum chosen for normal driving.

If the answer is yes at block514, the method proceeds to block516in which charge depleting control is used and the method proceeds back to the start.

If the answer at block514is no the method proceeds to518in which charge sustain control with a target at the predefined minimum for normal driving is used and the method proceeds back to the start.

If the answer at block502is yes, the method proceeds to block504where it is determined if the traction battery200state of charge is below a pre-set minimum chosen to provide enough reserve energy for the determined terrain mode/type.

If the answer at block504is yes, the method proceeds to block508in which the control system208acts to increase the state of charge of the traction battery200and the method returns to the start.

In acting to increase the state of charge of the traction battery200the control system208will, for example, use torque from the engine202of the vehicle10.

If the answer at block504is no, the method proceeds to block506in which it is determined if there has been a change such that a terrain mode with potential high electric traction demands from the traction motor212has been set.

If the answer at block506is yes, the method proceeds to block510in which charge sustain and control is used and the charge sustain set point is set to the prevailing state of charge of the traction battery200and the method returns to the start.

If the answer at block506is no the method proceeds to block512in which charge sustaining control is used with a charge sustain set point set at a level set when the answer at block506was last positive and the control returns to the start.

If there has never been a positive answer at block506a pre-set minimum, such as that considered in block504, can be used as the set point.

FIG.6illustrates a graph of traction battery state of charge as a function of time.

In the example ofFIG.6the solid line602illustrates the state of charge of the traction battery200without the inventive energy management control for the traction battery200described herein.

As can be seen by the solid line602, the state of charge of the traction battery200steadily decreases until the charge sustain set point30, illustrated by the dot-dashed line, is reached.

After this point, the state of charge of the traction battery200oscillates around the charge sustain set point30due to varying demands.

However, it can be seen inFIG.6that the charge sustain set point30is relatively low and, therefore, if the vehicle10were to encounter a driving surface, such as sand, requiring increased use of all-wheel drive there would not be sufficient state of charge for the traction battery200to provide all-wheel drive as required.

The dashed line604inFIG.6illustrates the state of charge of the traction battery200when using the inventive energy management control for the traction battery200as described herein.

In the example ofFIG.6the charge sustain set point30has been selected in dependence on a determined terrain mode and/or type and/or increase in loading of vehicle10at time t0, illustrated by the dashed vertical line, and has, in this example, been raised to be set point30′.

This is illustrated by the upper dot-dashed line30′ in the example ofFIG.6.

As can be seen by the dashed line604the state of charge of the traction battery200steadily decreases until the selected charge sustain set point30′ is reached after which the state of charge of the traction battery200is maintained at that level.

Accordingly, the state of charge of the traction battery200is higher for completing expected manoeuvres on a surface, such as sand, in which required provision of all-wheel drive is increased.

In the example ofFIG.6further dot-dashed lines31,33are illustrated below the charge sustain set point30.

These are thresholds31,33at which further control can be implemented, such as prohibiting electrical-only mode and prohibiting use of the traction motor212. In examples there can be a threshold at which electric traction in parallel hybrid operation begins to be reduced and a lower threshold by which electric traction in parallel hybrid operation is completely removed.

In the example ofFIG.6, when the inventive energy management control is used, the control system208will charge the traction battery200if the state of charge of the traction battery200is within the region indicated by the double headed arrow35.

In examples, how the charging occurs can be controlled in dependence on the determined terrain mode and/or type and/or increase in loading of the vehicle10.

For example, the control system208can control the engine202of the vehicle10to prioritise charging the traction battery200on certain terrain types compared to other terrain types where lower priority for charging the traction battery200is used.

FIG.7illustrates an example of controlling energy management of a traction battery200of a hybrid electric vehicle10.

In examples, the hybrid electric vehicle10is the vehicle inFIG.2.

The example ofFIG.7is split into two sections an upper section A and a lower section B. The upper section ofFIG.7can therefore be consideredFIG.7Aand the lower section ofFIG.7can be consideredFIG.7B.

The upper section A illustrates behaviour without the inventive control described herein.

InFIG.7Athree graphs are illustrated. The upper panel, graph1, illustrates a simplified version of electric traction required from the traction motor212as a function of time. The electric traction required is shown when particularly high amounts of torque are required compared to normal use.

The middle panel, graph2, illustrates electric traction deliverable as a function of time and the lower panel, graph3, illustrates traction battery200state of charge as a function of time.

In addition, two specific events at times702and704are marked inFIG.7A.

At time702the driver of the vehicle selects an off-road surface mode for the vehicle.

In the example ofFIG.7, the most extreme off-road conditions are encountered after the time indicated at704.

In the first period, before time702, the vehicle is driving in normal conditions and the control system208is allowing the battery state of charge to deplete to the charge sustain set point30, therefore, in this example, the battery state of charge decreases accordingly while full electric traction is deliverable.

It can be seen in the first panel ofFIG.7Athat in between times702and704moderate electric traction from the traction motor212is required in two periods.

In the example ofFIG.7A, when the periods of moderate torque from the traction motor212are required the battery state of charge is already relatively low as the charge sustain set point30has been reached prior to encountering the first significant increase in traction to be provided by the traction motor212.

In the middle time period between times702and704the electric traction power deliverable decreases as the battery state of charge is affected by the increased electric traction requirements.

As the charge sustain set point has been reached, the battery state of charge is increased after encountering the periods where moderate electric traction is required.

After time704it can be seen that two longer periods requiring higher levels of electric traction are encountered.

However, in the example ofFIG.7Athe battery state of charge is insufficient to deliver the electric traction power required to meet those demands. This can be seen from the low levels of deliverable torque after time704in plot2ofFIG.7A.

This means that, in this example, the vehicle10cannot deliver electric traction as required by the off-road conditions encountered after time704, causing a reduction in the driving ability of the vehicle10.

In the example ofFIG.7B, the inventive energy management control described herein is used.

In the example ofFIG.7Bthe same graphs are illustrated in panels one, two and three and the drive cycle is the same inFIG.7Bas that described in7A.

However, in the example ofFIG.7B, after time702, at which the different terrain mode is selected, the vehicle10charges the traction battery200increasing the state of charge of the traction battery200up to the point where the first period where moderate electric traction as required is encountered. In the example ofFIG.7B, a higher charge sustain set point30′ is used after the different terrain mode is selected at time702. In this example, the system requests more torque from the engine202to facilitate the BISG/CIMG to provide an increase in electrical power to the traction battery200, increasing the state of charge to the higher charge sustain set point30′.

This means that, in the example ofFIG.7B, the electric traction deliverable remains constant between times702and704when the periods requiring moderate electric traction are encountered.

As the state of charge of the traction battery200has been managed differently after time702, when time704is encountered inFIG.7B, and the longer periods of electric traction at higher levels are required, thanks to the requested increase in torque from the engine202, the BISG/CIMG supplies an increased level of electrical power to the traction battery200such that the battery state of charge is sufficient to deliver higher levels of electric traction to allow driving ability of the vehicle10to remain unaffected or to be significantly improved compared to the example ofFIG.7A.

As used herein “for” should be considered to also include “configured or arranged to”. For example, “a control system for” should be considered to also include “a control system configured or arranged to”.

For purposes of this disclosure, it is to be understood that the controller(s) described herein can each comprise a control unit or computational device having one or more electronic processors. A vehicle and/or a system thereof may comprise a single control unit or electronic controller or alternatively different functions of the controller(s) may be embodied in, or hosted in, different control units or controllers. A set of instructions could be provided which, when executed, cause said controller(s) or control unit(s) to implement the control techniques described herein (including the described method(s)). The set of instructions may be embedded in one or more electronic processors, or alternatively, the set of instructions could be provided as software to be executed by one or more electronic processor(s). For example, a first controller may be implemented in software run on one or more electronic processors, and one or more other controllers may also be implemented in software run on one or more electronic processors, optionally the same one or more processors as the first controller. It will be appreciated, however, that other arrangements are also useful, and therefore, the present disclosure is not intended to be limited to any particular arrangement. In any event, the set of instructions described above may be embedded in a computer-readable storage medium (e.g., a non-transitory computer-readable storage medium) that may comprise any mechanism for storing information in a form readable by a machine or electronic processors/computational device, including, without limitation: a magnetic storage medium (e.g., floppy diskette); optical storage medium (e.g., CD-ROM); magneto optical storage medium; read only memory (ROM); random access memory (RAM); erasable programmable memory (e.g., EPROM and EEPROM); flash memory; or electrical or other types of medium for storing such information/instructions.

It will be appreciated that various changes and modifications can be made to the present invention without departing from the scope of the present application.

The blocks illustrated inFIGS.4and/or5may represent steps in a method and/or sections of code in the computer program306. The illustration of a particular order to the blocks does not necessarily imply that there is a required or preferred order for the blocks and the order and arrangement of the block may be varied. Furthermore, it may be possible for some steps to be omitted.