Patent Publication Number: US-2023150474-A1

Title: Hybrid vehicle state of charge control

Description:
TECHNICAL FIELD 
     The present disclosure relates to a hybrid vehicle control system and methods. In particular, but not exclusively, it relates to a hybrid vehicle control system and methods to control state of charge of an energy storage means. 
     BACKGROUND 
     A plug-in hybrid electric vehicle (PHEV) is capable of driving in electric-only mode, depending on the state of charge of an energy storage means of the vehicle, such as a high voltage battery or batteries. When the energy storage means, such as the high voltage battery of the vehicle, is depleted and the vehicle is in charge sustain mode, the vehicle is not capable of driving in electric-only mode. This can often mean that the end portion of a journey cannot be driven in electric-only mode as by the end of the journey the energy storage means of the vehicle can often become depleted. This results in the plug-in hybrid electric vehicle driving the end portion of the journey using an internal combustion engine which results in air and noise pollution around built-up areas, which are often present at the end of a route/journey. 
     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, to improve, for example, noise and air pollution caused at the end of journeys/routes. 
     Aspects and embodiments of the invention provide a control system, a vehicle 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 a state of charge of energy storage means of a hybrid electric vehicle, the control system comprising one or more electronic controllers, the one or more electronic controllers configured to: receive destination data; determine a route to be travelled by the vehicle, the route comprising one or more characteristics, in dependence on the received destination data; and control the state of charge of the energy storage means in dependence on the route to allow the vehicle to travel an end portion of the route in an electric-only mode. 
     An advantage providing a reduction in air and/or noise pollution at the end portion of the route for which is typically in built-up, populous areas 
     The one or more controllers may collectively comprise: at least one electronic processor having an electrical input for receiving destination data and information associated with determining a route to be travelled by 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 electronic memory device and execute the instructions thereon so as to cause the control system to determine a route to be travelled by the vehicle and to control the state of charge of the energy storage means. 
     The one or more characteristics of the route may comprise at least one of: a length of route; an expected speed profile; a gradient profile; an expected traffic flow profile; and availability of a vehicle charger at the end of the route. 
     The destination data may be received from at least one input by a user of the vehicle. 
     Controlling the state of charge of the energy storage means may comprise selecting an energy management mode for at least a portion of the route. The energy management mode may be a charging mode or a harvesting mode. The charging mode may comprise controlling an engine of the vehicle to provide torque to allow electrical energy generation. The one or more electronic controllers may be configured to: segment the route into a plurality of segments in dependence on the one or more characteristics of the route; and assign an energy management mode to one or more of the plurality of segments. 
     Controlling the state of charge of the energy storage means may comprise controlling: an electrical energy usage of the vehicle; an electrical energy storage of the vehicle; and/or an electrical energy generation of the vehicle. 
     The end portion of the route may be substantially the final 1 to 2 kilometres of the route, optionally the final 1.5 km. 
     Controlling the electrical energy storage of the vehicle may comprise allowing the state of charge of the energy storage means of the vehicle to fall below a charge sustain threshold of the vehicle to allow the vehicle to travel the end portion of the route in electric-only mode. 
     Controlling electrical energy storage of the vehicle may comprise allowing the state of charge of the energy storage means of the vehicle to fall below a charge sustain threshold in dependence on the availability of at least one vehicle charger at the end of the route. 
     According to an aspect of the invention there is provided a vehicle system comprising the control system and one or more components of a hybrid electric vehicle powertrain. 
     According to an aspect of the invention there is provided a vehicle comprising the control system or the vehicle system. 
     According to an aspect of the invention there is provided a method for controlling a state of charge of energy storage means of a hybrid electric vehicle, the method comprising: receiving destination data; determining a route to be travelled by the vehicle, the route comprising one or more characteristics, in dependence on the received destination data; and controlling the state of charge of the energy storage means in dependence on the route to allow the vehicle to travel an end portion of the route in an electric only mode. 
     The one or more characteristics of the route may comprise at least one of: a length of route; an expected speed profile; a gradient profile; an expected traffic flow profile; and availability of a charger at the end of the route. 
     The destination data is received from at least one input by a user of the vehicle. 
     Controlling the state of charge of the energy storage means may comprise selecting an energy management mode for at least a portion of the route. The energy management mode may be a charging mode or a harvesting mode. The charging mode may comprise controlling an engine of the vehicle to provide torque to allow electrical energy generation. 
     The method may comprise: segmenting the route into a plurality of segments in dependence on the one or more characteristics of the route; and assigning an energy management mode to one or more of the plurality of segments 
     Controlling the state of charge of the energy storage means may comprise controlling: an electrical energy usage of the vehicle; an electrical energy storage of the vehicle; and/or an electrical energy generation of the vehicle. 
     Controlling the electrical energy storage of the vehicle may comprise allowing the state of charge of the energy storage means of the vehicle to fall below a charge sustain threshold of the vehicle to allow the vehicle to travel the end portion of the route in electric-only mode. 
     Controlling electrical energy storage of the vehicle may comprise allowing the state of charge of the energy storage means of the vehicle to fall below a charge sustain threshold in dependence on the availability of at least one vehicle charger at the end of the route. 
     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, perform any one or more of the methods described herein. 
     Within the scope of this application it is expressly intended that the various aspects, embodiments, examples and alternatives set out in the preceding paragraphs, in the claims and/or in the following description and drawings, and in particular the individual features thereof, may be taken independently or in any combination. That is, all embodiments and/or features of any embodiment can be combined in any way and/or combination, unless such features are incompatible. The applicant reserves the right to change any originally filed claim or file any new claim accordingly, including the right to amend any originally filed claim to depend from and/or incorporate any feature of any other claim although not originally claimed in that manner. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       One or more embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG.  1    illustrates an example of a vehicle; 
         FIG.  2 A  schematically illustrates an example of a control system; 
         FIG.  2 B  schematically illustrates an example of a non-transitory computer-readable medium; 
         FIG.  3    schematically illustrates an example of a vehicle system; 
         FIG.  4    illustrates an example of a method; 
         FIG.  5    illustrates an example scenario; and 
         FIG.  6    illustrates an example scenario. 
     
    
    
     DETAILED DESCRIPTION 
     Examples of the present disclosure relate to controlling state of charge of an energy storage means of a hybrid electric vehicle. In examples, the energy storage means can be any suitable energy storage means to power one or more electric traction motors of the hybrid electric vehicle to propel the vehicle. 
     In examples, the energy storage means can be considered: one or more components configured to store energy, energy storage circuitry, energy storage apparatus, energy storage mechanisms and so on. In examples, the energy storage means comprises or is one or more traction batteries which may be one or more high voltage batteries. 
     In examples, the state of charge of the energy storage means is controlled in dependence on the route to allow the vehicle to travel an end portion of the route in an electric-only mode. In examples, the end portion of the route is substantially the final 1-2 km of the route, optionally the final 1.5 km. In examples, the end portion of the route is substantially the last mile or 1.62 km of the route. 
     Controlling a state of charge of the energy storage means to allow the vehicle to travel an end portion of the route in electric-only mode is advantageous as, for example, it providing a reduction in air and/or noise pollution at the end portion of the route for which is typically in built-up, populous areas. Furthermore, this can improve the electric only mode perception of the vehicle. 
     One or more of the features discussed in relation to  FIGS.  1 ,  2 A,  2 B and  3    can be found in the other figures. 
       FIG.  1    illustrates an example of a vehicle  10  in which embodiments of the invention can be implemented. In the illustrated example, the vehicle  10  is a hybrid electric vehicle  16  (HEV). In some, but not necessarily all, examples, the vehicle  10  is 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. 
     In examples the hybrid electric vehicle  16  has an electric-only mode of propulsion among other modes of propulsion. In examples, the HEV is 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. Parallel HEVs differ from series HEVs, because in series HEVs the purpose of the engine is generate electrical energy and there is no torque path between the engine and vehicle wheels. 
       FIG.  2 A  illustrates an example of a control system  12 . In the illustrated example, the control system  12  is a control system  12  for controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16 . 
     In examples, any suitable control system  12  for controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16  can be used. 
     The control system  12  of  FIG.  2 A  comprises an electronic controller  18 . In other examples, the control system  12  comprises a plurality of electronic controllers  18  on board and/or off board the vehicle  10 ,  16 . 
     The electronic controller  18  of  FIG.  2 A  comprises at least one electronic processor  24  and at least one electronic memory device  28  electrically coupled to the at least one electronic processor  24  and having instructions  30  (for example a computer program) stored therein, the at least one electronic memory device  28  and the instructions  30  configured to, with the at least one electronic processor  24 , cause any one or more of the method or methods described herein to be performed. 
     Accordingly,  FIG.  2 A  illustrates a control system  12  for controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16 , the control system  12  comprising one or more electronic controllers  18 , the one or more electronic controllers  18  configured to:
     receive destination data;   determine a route  20  to be travelled by the vehicle  16 , the route  20  comprising one or more characteristics, in dependence on the received destination data; and   control the state of charge of the energy storage means  14  in dependence on the route  20  to allow the vehicle  16  to travel an end portion  22  of the route  20  in an electric-only mode.   

     In examples, the end portion of the route is substantially the final 1-2 km of the route, optionally the final 1.5 km. In examples, the end portion of the route is substantially the last mile or 1.62 km of the route. 
     Furthermore,  FIG.  2 A  therefore illustrates a control system  12 , wherein the one or more controllers  18  collectively comprise:
     at least one electronic processor  24  having an electrical input for receiving destination data and information associated with determining a route  20  to be travelled by the vehicle  16 ; and   at least one electronic memory device  28  electrically coupled to the at least one electronic processor  24  and having instructions  30  stored therein;   and wherein the at least one electronic processor  24  is configured to access the at least one electronic memory device  28  and execute the instructions  30  thereon so as to cause the control system  12  to determine a route  20  to be travelled by the vehicle  16  and to control the state of charge of the energy storage means  14 .   

       FIG.  2 B  illustrates a non-transitory computer-readable storage medium  40  comprising the instructions  30  (computer software). Accordingly,  FIG.  2 B  illustrates a non-transitory computer-readable medium  40  comprising computer-readable instructions  30  that, when executed by a processor  24 , perform the method of  FIG.  4    and/or as described herein. 
       FIG.  3    illustrates an example of a vehicle system  38 . In the illustrated example, the vehicle system  38  is a system for controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16 . 
       FIG.  3    also illustrates an example of a vehicle  10 , such as a hybrid electric vehicle  16 , comprising a control system  12  as described herein and/or a vehicle system  38  as described herein. 
     In the example of  FIG.  3   , the vehicle system  38  comprises a control system  12  which may be as described in relation to  FIG.  2 A . In the example of  FIG.  3   , the vehicle system  38  comprises one or more vehicle systems  42 , which may be considered further vehicle system(s)  42 , one or more transceivers  44  and one or more user interfaces  46 . 
     In the example of  FIG.  3   , the control system  12  provides means for controlling operation of the vehicle system  38 . However, in examples, any suitable means for controlling operation of the vehicle system  38  may be used. 
     The control system  12  of  FIG.  3    may 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. 
     As illustrated in the example of  FIG.  3   , the elements  42 ,  44  and  46  are operationally coupled to the control system  12  and any number or combination of intervening elements can exist between them (including no intervening elements). In some examples, at least some of the elements  42 ,  44  and  46  are operationally coupled to each other and/or share one or more components. Additionally, or alternatively, the elements  42 ,  44  and  46  may be operationally coupled to and/or share one or more components with other elements not illustrated in the example of  FIG.  3   . 
     In examples, the one or more vehicle systems  42  are any suitable vehicle system(s)  42  of the vehicle  10 ,  16 . For example, the one or more vehicle systems  42  may comprise any suitable vehicle system(s)  42  of the vehicle  10 ,  16  controllable, at least in part, by the control system  12 . In examples, the one or more vehicle systems  42  comprise one or more vehicle systems  42  used in controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16 . 
     The vehicle system(s)  42  may be considered further vehicle system(s)  42  comprised in a vehicle system  38 . In examples, the one or more vehicle systems  42  comprise one or more vehicle components involved in electrical energy usage of the vehicle  10  and/or one or more vehicle components involved in electrical energy storage of a vehicle  10  and/or one or more vehicle components involved in electrical energy generation of the vehicle  10 . 
     In some examples, the one or more vehicle systems  42  comprise one or more components of a hybrid electric vehicle powertrain. Accordingly, in examples, there is provided a vehicle system  38  comprising a control system  12  as described herein and one or more components of a hybrid electric vehicle powertrain. 
     In examples a hybrid electric vehicle powertrain comprises at least one engine. The engine may be a combustion engine. In some examples the engine is an internal combustion engine. 
     The control system  12  is, in examples, operably coupled to the engine to enable the control system to control output torque of the engine. The output torque of the engine may 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 engine. 
     In examples a hybrid electric vehicle powertrain comprises at least one electric traction motor. The at least one electric traction motor may be an alternating current induction motor or a permanent magnet motor, another type of motor or any suitable combination of such motors. 
     The control system  12  is, in examples, operably coupled to the at least one electric traction motor to enable the control system to control output torque of the electric traction motor(s). In examples at least one of the at least one electric traction motor is configured to provide torque to allow the vehicle  10 ,  16  to travel in an electric-only mode. 
     In examples, the one or more vehicle systems  42  comprise the energy storage means  14  of the vehicle  10 . In some examples, the energy storage means  14  can be part of a hybrid electric vehicle powertrain. 
     In examples, the energy storage means  14  comprise one or more traction batteries, which may be high voltage batteries, configured to store electrical energy for the electric traction motor(s). 
     In examples the one or more traction batteries provide a nominal voltage required by electrical power users such as electric traction motors. If the electric traction motors run at different voltages, DC-DC converters or the like may be provided to convert voltages. In examples where an AC motor is used an inverter can be used to provide power from a DC source. 
     In some examples the one or more traction batteries is a high voltage battery. High voltage traction batteries provide nominal voltages in the hundreds of volts, as opposed to traction batteries for mild HEVs which provide nominal voltages in the tens of volts. The one or more traction batteries may have a voltage and capacity to support electric-only driving for sustained distances. The one or more traction batteries may 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. 
     In examples, the one or more vehicle systems  42  comprise one or more energy regeneration systems of the vehicle  10 . 
     In examples, the one or more energy regeneration systems of the vehicle  10  can comprise any suitable system for generating energy, such as electrical energy, while the vehicle  10  travels to a desired destination. In examples, the one or more energy regeneration systems comprises one or more regenerative braking systems, one or more solar regenerative systems and so on. Other energy regeneration systems are useful, such as any regenerative system configured to convert kinetic energy of the vehicle into electrical energy which can be used to charge energy storage means  14 . 
     In examples, the one or more electric traction motors can form at least part of an energy regeneration system(s) of the vehicle systems  42 . 
     In examples, the control system  12  provides means for controlling operation of the one or more vehicle systems  42 . Information may be transmitted between the control system  12  and the one or more vehicle systems  42 . For example, control information may be transmitted from the control system  12  to the one or more vehicle systems  42  and/or information from the one or more vehicle systems  42 , such as information regarding energy storage levels of the vehicle  10 , transmitted to the control system  12 . 
     This is illustrated in the example of  FIG.  3    by the double-headed arrow linking the one or more vehicle systems  42  and the control system  12 . 
     The one or more user interfaces  46  comprise any suitable user interface(s) for or configured to receive user input from a user, such as one or more occupants of a vehicle  10 . For example, any suitable user interface(s)  46  for receiving at least one input by a user of the vehicle to provide destination data and/or route information and/or location information of the vehicle  10 ,  16 . 
     That is, in some examples, the one or more user interfaces  46  provide means for a user, such as an occupant or user of the vehicle  10 , to input destination data. 
     In examples, the one or more user interfaces  46  comprise one or more displays, one or more keyboards, one or more touch sensitive inputs, one or more joysticks, one or more microphones, one or more cameras, one or more radar interfaces and/or one or more proximity sensors and so on. 
     In examples, the control system  12  provides means for controlling operation of the one or more user interfaces  46 . Information may be transmitted between the control system  12  and the one or more user interfaces  46 . For example, control information may be transmitted from the control system  12  to the one or more user interfaces  46  and/or information from the one or more user interfaces  46 , such as destination data input via the one or more user interfaces  46 , transmitted to the control system  12 . This is illustrated in the example of  FIG.  3    by the double-headed arrow linking the one or more user interfaces  46  and the control system  12 . 
     The one or more transceivers  44  are for receiving and/or transmitting one or more signals. For example, the one or more transceivers  44  may be for receiving and/or transmitting one or more wireless signals. Any suitable transceiver or transceivers can be used and, in some examples, separate transmitter(s) and/or receiver(s) may be used. 
     The one or more transceivers  44  are for transmitting and/or receiving wireless signals over any suitable range. For example, the one or more transceivers  44  may be configured to receive and/or transmit electromagnetic signals over any suitable range. 
     In some examples, the one or more transceivers  44  are configured to receive and/or transmit electromagnetic signals using one or more shorter range protocols such as Bluetooth and/or wi-fi. Additional or alternatively, the one or more transceivers  44  may be configured to receive and/or transmit electromagnetic signals using one or more longer range protocols such as one or more cellular telephone protocols. 
     In examples, the one or more transceivers  44  are for transmitting and/or receiving wireless signal(s) comprising information. For example, the one or more transceivers  44  may be configured to transmit and/or receive wireless signal(s) comprising destination data and/or route information and/or location information of the vehicle  10 ,  16 . 
     In examples, the one or more transceivers  44  are configured to receive one or more signals from a personal device of a user of the vehicle  10 , such as a mobile phone, to allow the user of the vehicle to input information, such as destination data. 
     In examples, the one or more transceivers  44  may be considered to be at least part of the one or more user interfaces as the one or more transceivers  44  may be used to receive information, such as destination data, from/transmit information to a personal device of a user such as an occupant of the vehicle  10 . 
     In examples, the control system  12  provides means for controlling operation of the one or more transceivers  44 . Information may be transmitted between the control system  12  and the one or more transceivers  44 . For example, control information may be transmitted from the control system  12  to the one or more transceivers  44  and/or data/information received in one or more wireless signals transmitted to the control system  12 . This is illustrated in the example of  FIG.  3    by the double-headed arrow linking the one or more transceivers  44  and the control system  12 . 
     In examples, the control system  12  provides means for controlling the elements of the vehicle system  38 . The control system  12  may be configured to control the elements of the vehicle system  38  using one or more wired or wireless network systems/protocols. For example, USB, HTMI, Bluetooth, wi-fi, CAN, LIN, i2c, FNET, FBD-link, UART, SBI and so on may be used. 
     In the example of  FIG.  3   , the vehicle system  38  is comprised in the vehicle  10 , which is a hybrid electric vehicle  16 . 
     The vehicle system  38  may comprise any number of additional elements not illustrated in the example of  FIG.  3   . Additionally or alternatively, one or more elements of the vehicle system  38  illustrated in the example of  FIG.  3    may be integrated and/or combined. For example, the one or more transceivers  44  and the one or more user interfaces  46  may be at least partially combined. 
     In some examples, one or more of the elements illustrated in the example of  FIG.  3    may be omitted from the vehicle system  38 . For example, the one or more transceivers  44  may be omitted from the vehicle system  38 . 
       FIG.  4    illustrates an example of a method  400 . The method  400  is for controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16 . In examples, the vehicle  10 ,  16  can be a vehicle  10 ,  16  as illustrated in  FIG.  1    and/or 3. 
     In examples, the method  400  is performed by the control system  12  of  FIGS.  2 A or  3    or the vehicle system  38  of  FIG.  3   . That is, in examples, the control system  12  described herein comprises means for performing the method  400 . However, any suitable means may be used to perform the method  400 . 
     At block  402  destination data is received. In examples, the destination data can be received in any suitable way. In some examples, the destination data is received from at least one input by a user of the vehicle  10 ,  16 . 
     For example, the at least one input by a user of the vehicle  16  can be made using one or more user interfaces  46  as described in relation to  FIG.  3   . 
     In examples, the destination data provides information concerning a destination to which the vehicle  16  is to travel. That is, in examples, the destination data provides information as to the end point of a route that the vehicle  16  is to travel. 
     Any suitable destination data in any suitable form can be used. For example, any suitable destination data that allows for determination of a route to the desired destination can be used. 
     At block  404  a route  20  to be travelled by the vehicle  10 ,  16 , the route  20  comprising one or more characteristics, is determined in dependence on the received destination data. Any suitable method for determining a route  20  to be travelled by the vehicle  10 ,  16  in dependence on the received destination data can be used. 
     As used herein, determining a route  20  is intended to include processing information such as the destination data, current location of the vehicle  10 ,  16  and map information to determine the route  20  and also to include receiving the route  20  to be travelled by the vehicle. 
     In some examples, a user of the vehicle  10 ,  16  can confirm the route to be travelled by making one or more inputs via the one or more user interfaces  46  of  FIG.  3   . 
     In examples, the characteristics of the route  20  can comprise any suitable characteristic or characteristics of the route  20  that can be used by the control system  12  to control the state of charge of the energy storage means  14  of the vehicle  10 ,  16  to allow the vehicle  10 ,  16  to travel an end portion  22  of the route  20  in an electric only mode. 
     In some examples, the one or more characteristics of the route comprises at least one of: a length of route, an expected speed profile, a gradient profile, an expected traffic flow profile and availability of a vehicle charger at the end of the route. 
     In examples, the length of the route can be considered to be the total distance to be travelled by the vehicle  10 ,  16  along the route  20 . 
     In examples, the expected speed profile can be considered to be the profile of the expected speed of the vehicle  10 ,  16  along the route  20 . The expected speed profile can be influenced by a number of factors. 
     For example, the expected speed profile can be influenced by on one or more of: speed limits along the route  20 , average speeds along the route  20 , traffic information along the route  20  and so on. The expected traffic flow profile may be based on the expected speed profile and be further refined using predictive and/or historical traffic information based on the day of the week and time of day that the journey started and is predicted to end. The expected traffic flow profile may be calculated with the vehicle  10 ,  16  and/or may be calculated remotely and provided as a cloud-based service accessible to the vehicle  10 ,  16  and/or a portable electronic device such as a mobile phone carried by a user of the vehicle  10 ,  16 . 
     In some examples, the expected speed profile can be influenced by and/or dependent on the expected traffic flow profile. The expected speed profile can represent the expected speed variation of the vehicle  16  along the route  20 . In examples the expected speed profile can be determined for different segments of the route  20 . 
     In examples, the gradient profile can be considered to be a profile of the gradient or gradients that the vehicle  10 ,  16  will encounter as the vehicle  10 ,  16  travels along the route  20  to the destination. Such information can, for example, allow determination of sections of the route  20  where energy can be regenerated by the vehicle  10 ,  16 . 
     In examples, a vehicle charger can be considered to be a charger configured to charge the energy storage means  14  of the vehicle  16 . 
     At block  406  the state of charge of the energy storage means  14  is controlled in dependence on the route  20  to allow the vehicle  10 ,  16  to travel an end portion  22  of the route  20  in an electric-only mode. For example, the end portion  22  of the route  20  can, in examples, be the end 1.5 km of the route  20 . 
     Any suitable method for controlling the state of charge of the energy storage means  14  in dependence on the route  20  to allow the vehicle  10 ,  16  to travel an end portion  22  of the route  20  in an electric-only mode can be used. 
     In examples, the amount of energy required to travel the end portion  22  of the route  20  in an electric-only mode can be determined or estimated and the state of charge of the energy storage means  14  controlled as the vehicle  10 ,  16  travels along the route  20  to ensure that sufficient charge is present in the energy storage means  14  to allow the vehicle  10 ,  16  to travel the end portion  22  of the route  20  in an electric-only mode. 
     In examples, controlling the state of charge of the energy storage means  14  comprises determining energy harvesting opportunities via regeneration to allow electric-only mode at the end portion  22  of the route  20 . 
     In examples, controlling the state of charge of the energy storage means comprises controlling: an electrical energy usage of the vehicle  16 ; an electrical energy storage of the vehicle  16 ; and/or an electrical energy generation of the vehicle  16 . 
     For example, controlling the state of charge of the energy storage means  14  can comprise controlling use of electric motor(s) of the vehicle  16 ; controlling use of energy regeneration system(s) of the vehicle  16  and/or controlling state of charge thresholds of energy storage means  14  of the vehicle  16 . 
     In examples, controlling the electrical energy storage of the vehicle  16  comprises allowing the state of charge of the energy storage means  14  of the vehicle  16  to fall below a charge sustain threshold of the vehicle  16  to allow the vehicle  16  to travel the end portion  22  of the route  20  in electric only mode. 
     In examples a charge sustain threshold can be considered a threshold around which the state of charge of the energy storage means will be held. In examples the state of charge of the energy storage means  14  may temporally fall below the charge sustain threshold due to transient energy demands. However, the vehicle  10 ,  16  will try to recharge the energy storage means  14  to maintain the state of charge of the energy storage means  14  at or above the charge sustain threshold. 
     In some examples, controlling electrical energy storage of the vehicle  16  comprises allowing the state of the charge of the energy storage means  14  over the vehicle  16  to fall below a charge sustain threshold in the end portion  22  of the route  20  to allow the vehicle  16  to travel the end portion  22  of the route  20  in electric only mode. 
     In some examples, controlling electrical energy storage of the vehicle  16  comprises allowing the state of charge of the energy storage means  14  of the vehicle  16  to fall below a charge sustain threshold in dependence on the availability of at least one vehicle charger at the end of the route  20 . 
     In examples, the vehicle  16  comprises energy management modes that can be used to control a state of charge of the energy storage means  14  of the vehicle  16 . 
     Accordingly, in examples, controlling the state of charge of the energy storage means  14  comprises selecting an energy management mode for at least a portion of the route  20 . In some examples an energy management mode can be selected for the whole route  20 . 
     In examples, the energy management mode is a charging mode or a harvesting mode. 
     In a charging mode the energy storage means  14  of the vehicle  16  is charged with an engine of the vehicle  16 . 
     In harvesting mode energy is stored by inhibiting use of one or more electric motors of the vehicle  16  for providing positive torque. For example, in harvest mode torque assist, in which torque from an electric motor can replace part of the torque from an internal combustion engine, can be inhibited. In harvesting mode the one or more electric motors can be used to convert kinetic energy of the vehicle into electrical energy which can be used to recharge the energy storage means  14 . 
     Therefore, in examples, charging mode comprises controlling an engine of the vehicle  16  to provide torque to allow electrical energy generation. In examples, the amount of torque provided by the engine of the vehicle  16  can be controlled to control the amount of electrical energy generation. 
     That is, generation of energy can be given a greater or reduced priority in dependence on the route  20  to ensure that sufficient energy is present to allow the end portion  22  of the route  20  to be travelled in an electric-only mode. 
     In some examples, the method  400  comprises segmenting the route  20  into a plurality of segments  32  in dependence on the one or more characteristics of the route; and assigning an energy management mode to one or more of the plurality of segments  32 . See, for example,  FIGS.  5  and  6   . 
     In examples, the route  20  can be segmented into a plurality of segments  32  in any suitable way using any suitable method. 
     In examples, the route  20  can be segmented into a plurality of segments  32  in dependence on the length of the route  20 , the expected speed profile along the route  20 , the expected gradient profile along the route  20 , the expected traffic flow profile of the route and/or the availability of a vehicle charger at the end of the route  20 . 
     In examples, the method  400  can be adaptive. That is, if the route  20  changes the control system  12  can adapt control of the state of charge of the energy storage means  14  in dependence on the change to ensure that an end portion  22  of the route  20  can be travelled in an electric-only mode. 
     For example, the expected speed profile and/or traffic profile of the route  20  may change due to, for example, changes in traffic along the route  20  and the control of the state of charge of the energy storage means  14  may be changed in dependence on the change, by, for example, changing the amount of energy to be harvested and/or obtained through charging by an engine. 
     In examples, segmentation of the route  20  may dynamically change in dependence on dynamically changing characteristics of the route  20 . 
     A technical effect of the method  400  is a reduction in noise and/or air pollution at the end portions of routes  20  which are typically built-up and populace. 
     In some examples a speed threshold for electric only mode is used to ensure that the vehicle  16  can travel the end portion  22  of the route  20  in electric only mode. In such examples, the route  20  is segmented into a plurality of segments  32 , each segment having an associated speed, length and gradient. The last segment can be considered the end portion  22  of the route  20 . 
     The route  20  can be split into speed bands, for example, 0 to 5 kph, 5 to 10 kph, 10 to 15 kph and so on, up to a maximum band, for example 145 to 150 kph. However, in examples, any suitable speed bands can be used. 
     The energy demand for each segment  32  of the route  20  can be determined or estimated using the following equation: 
     
       
         
           
             
               E 
               
                 s 
                 e 
                 g 
                 m 
                 e 
                 n 
                 t 
               
             
             
               J 
             
             = 
             
               
                 
                   C 
                   1 
                 
                 + 
                 
                   C 
                   2 
                 
                 ⋅ 
                 
                   V 
                   
                     s 
                     e 
                     g 
                     m 
                     e 
                     n 
                     t 
                   
                 
                 + 
                 
                   C 
                   3 
                 
                 ⋅ 
                 
                   V 
                   
                     s 
                     e 
                     g 
                     m 
                     e 
                     n 
                     t 
                   
                   2 
                 
                 + 
                 m 
                 ⋅ 
                 g 
                 ⋅ 
                 
                   
                     
                       S 
                       
                         s 
                         e 
                         g 
                         m 
                         e 
                         n 
                         t 
                       
                     
                     
                       % 
                     
                   
                   
                     100 
                   
                 
               
             
             ⋅ 
             
               L 
               
                 s 
                 e 
                 g 
                 m 
                 e 
                 n 
                 t 
               
             
             
               m 
             
           
         
       
     
     Where: C 1 , C 2  and C 3  are road load coefficients, E segment  is the energy required for each segment, V segment  is the speed of each segment, m is the mass of the vehicle, g is acceleration due to gravity, S segment  is the gradient of each segment and L segment  is the length of each segment. 
     The road load coefficients take into account factors such as vehicle mass, aerodynamic drag, road drag and so on. The road load coefficients can be determined in any suitable way. For example, the road load coefficients can be determined using theory, using one or more models, using one or more experiments and/or using one or more simulations and so on. 
     The energy demand for the last segment  32 , or end portion  22 , of the route  20  can be determined using the above formula. This can be considered E arrival [J]. 
     The total energy stored in the energy storage means  14  can be obtained (E total [J]) and the energy available for the segments  32  excluding the final segment  32  calculated via: 
     
       
         
           
             
               E 
               
                 available 
               
             
             
               J 
             
               
             = 
               
             
               E 
               
                 total 
               
             
             
               J 
             
               
             - 
               
             
               E 
               
                 arrival 
               
             
             
               J 
             
           
         
       
     
     All the energies, for the segments  32  other than the final segment, in a speed band, can be summed up, starting with the lowest band, until the summed value reaches E available . 
     The speed threshold for electric only mode on the route  20  is the average speed of the last or highest speed band which can be covered by E available . Thus a speed threshold for electric only mode for the route  20  can be determined to ensure that the end portion  22  of the route  20  can be travelled in electric only mode. 
       FIG.  5    illustrates an example of controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16 . 
     The upper section of  FIG.  5    schematically illustrates a route  20  with the end portion  22  of the route  20  being to the right of the figure. The example of  FIG.  5    is not shown to scale. The gradient profile of the route is schematically illustrated. 
     The lower portion of  FIG.  5    illustrates a plot of state of charge of energy storage means  14  of the vehicle  16  on the y axis and route distance along the x axis. The solid line  48  on the plot illustrates the state of charge of the energy storage means  14  without control of the energy storage means  14  to allow the vehicle to travel the end portion  22  of the route  20  in an electric-only mode. 
     The dot dashed line  50  illustrates the state of charge of the energy storage means  14  with the control described herein. The dashed line  34  in the plot of  FIG.  5    illustrates the charge sustain threshold for the vehicle  16 . 
     In the example of  FIG.  5   , the route  20  has been segmented into six different portions or segments  32  labelled A to F in dependence on characteristics of the route  20 . The end portion  22  of the route  20  is portion F and is, in this example, the final 1.5 km of the route  20 . 
     In the example of  FIG.  5    the route  20  has been segmented in dependence on the gradient profile and expected speed profile of the route  20 . Furthermore, no vehicle charger is available at the end of the route  20  in the example of  FIG.  5   . 
     The segments A and B have been separated as, in the example, segment A has a lower speed limit than segment B. 
     In the example of  FIG.  5   , segment C has been determined in dependence, at least, on the uphill gradient and segment D at least on the downhill gradient. 
     Sections E and F have been segmented to create a section for the end portion  22  of the route  20 . 
     First considering the solid line  48  of the plot of  FIG.  5    without control of the state of charge of the energy storage means  14  as described herein. 
     As can be seen by the solid line  48 , at the start of the journey the state of charge of the energy storage means  14  is high and the vehicle proceeds in electric-only mode depleting the state of charge of the energy storage means  14 . Without the control of the state of charge, the state of charge of the energy storage means  14  continues to deplete until the charge sustain threshold  34  is hit at which point the state of charge of the vehicle  16  is maintained at the charge sustain threshold  34 . In this scenario, with the vehicle in a charge sustain condition, the traction motor will not be used to provide electric-only propulsion until the battery state of charge is above the charge sustain threshold  34 . 
     It is therefore evident that without the control of the state of charge of the energy storage means  14  along the route  20  of  FIG.  5    the last portion  22 , F of the route  20  could not be travelled in electric-only mode. 
     Now considering the dot dashed line  50  illustrating the state of charge of the energy storage means  14  when controlled as described herein. 
     In section A the vehicle  16  also travels in electric-only mode depleting the state of charge of the energy storage means  14 . However, in section B the state of charge of the energy storage means  14  is held. In the example, this is done through use of an engine of the vehicle  16 . 
     In section C the vehicle must travel up an incline and some energy from the energy storage means  14  is used to assist in doing so reducing the state of charge. 
     However, in section D the vehicle  16  travels down an incline allowing energy regeneration to increase the state of charge of the vehicle  16 . In section D the vehicle 6 is put into a harvesting mode. 
     In section E the state of charge of the vehicle is again held which ensures that there is sufficient state of charge in the energy storage means  14  of the vehicle  16  to allow the vehicle  16  to travel the end portion  22  (section F) of the route  20  in electric only mode. 
     Accordingly, it can be seen in the example of  FIG.  5    that controlling the state of charge of the energy storage means  14  in dependence on the route allows electric only mode in the end portion  22  reducing air and noise pollution in the end portion  22 . Furthermore, doing so can improve the perception of the electric only mode of the vehicle. 
     In the example of  FIG.  5   , the amount of energy needed to travel the end portion  22  of the route  20  in electric-only mode is determined and the control of the state of charge along the route  20  planned to provide sufficient energy in the end portion  22 . For example, it is determined to hold the state of charge in section B and to put the vehicle  16  into harvest mode in section D. 
       FIG.  6    illustrates an example of controlling a state of charge of energy storage means  14  of a hybrid electric vehicle  16 . 
     In the example of  FIG.  6   , the same route and route segmentation is shown in the schematic illustration and plot of state of charge versus distance along the route  20 . 
     However, in the example of  FIG.  6   , the state of charge of the energy storage means  14  starts at the charge sustain threshold  34 . 
     In  FIG.  6    the state of charge, without the control described herein, is again shown by the solid line  48 . 
     In the example of  FIG.  6   , as the state of charge of the energy storage means  14  begins at the charge sustain threshold  34  it is maintained at this threshold  34  throughout the journey. 
     In  FIG.  6    the state of charge of the energy storage means  14 , with the control described herein, is again illustrated by the dot dashed line  50 . 
     Over the first section, A, the state of charge also remains at the charge sustain threshold  34 . 
     However, in section B, in the case of using the control described herein, the vehicle  16  is put into a charging mode and an engine of the vehicle is controlled to provide torque to allow charging of the energy storage means  14 . Accordingly, the state of charge of the energy storage means in section B increases as illustrated by the dot dashed line  50 . 
     In other examples where there are more regenerative opportunities along a route harvest mode could be used instead of charging mode. 
     In section C of  FIG.  6   , similarly to section C of  FIG.  5   , the vehicle  16  must travel up an incline and therefore some energy is used in doing so and the state of charge of the energy storage means  14  decreases accordingly. 
     At section D, in  FIG.  6   , similarly to  FIG.  5   , the vehicle harvests energy via regeneration as the vehicle  16  travels down an incline and the state of charge is, again, held in section E. 
     The vehicle  16  is again, similarly to  FIG.  5   , put into a harvest mode in section D. 
     This, again, provides sufficient state of charge for the vehicle  16  to traverse the end portion  22  of the route  20  (section F) in electric-only mode. 
     In the example of  FIG.  6   , the state of charge of the energy storage means  14  is less at the beginning of section F compared to the state of charge in  FIG.  5   . 
     However, in the example of  FIG.  6   , a charger is present at the destination and therefore the state of charge of the energy storage means  14  is allowed to fall below the charge sustain threshold  34  of the vehicle  16  to allow the vehicle  16  to travel the end portion  22  of the route  20  in electric only mode. 
     If, for example, no charger were present at the destination in the example of  FIG.  6    the generation of energy could be more actively prioritised in portion B to ensure that the end portion  22  of the route  20  could be travelled in electric only mode without falling below the charge sustain threshold of the vehicle. 
     In the example of  FIG.  6   , the amount of energy needed to travel the end portion  22  of the route  20  in electric-only mode is determined and the control of the state of charge along the route  20  planned to provide sufficient energy in the end portion  22 . For example, it is determined to put the vehicle into charging mode in section B and to put the vehicle  16  into harvest mode in section D. 
     However, in the example of  FIG.  6   , it is determined that less energy is required to drive the end portion  22  in electric-only mode as a vehicle charger is present at the end of the route  20  and the state of charge is therefore allowed to fall below the charge sustain threshold in the end portion  22 . 
     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 in the  FIG.  4    may represent steps in a method and/or sections of code in the computer program  30 . 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. 
     Although embodiments of the present invention have been described in the preceding paragraphs with reference to various examples, it should be appreciated that modifications to the examples given can be made without departing from the scope of the invention as claimed. 
     Features described in the preceding description may be used in combinations other than the combinations explicitly described. 
     Although functions have been described with reference to certain features, those functions may be performable by other features whether described or not. 
     Although features have been described with reference to certain embodiments, those features may also be present in other embodiments whether described or not. 
     Whilst endeavoring in the foregoing specification to draw attention to those features of the invention believed to be of particular importance it should be understood that the Applicant claims protection in respect of any patentable feature or combination of features hereinbefore referred to and/or shown in the drawings whether or not particular emphasis has been placed thereon.