Range estimation for a vehicle

Abstract

A control system 400, comprising one or more processors 402, controls a vehicle range estimation system of an electric vehicle (EV). The control system obtains a first range signal 408 indicative of a

Description

TECHNICAL FIELD The present disclosure relates to range estimation for a vehicle. Aspects of the invention relate to a control system for controlling a vehicle range estimation system, to a system, to a vehicle range estimation system, to a vehicle, and to a method for controlling a vehicle range estimation system. BACKGROUND For vehicles with electric drivetrains, it is known to estimate the energy usage of a future journey based on a predetermined average energy usage per unit distance. Such information may be useful for estimating a range of the vehicle, for planning recharging, or for informing the driver of the predicted remaining battery energy at arrival. However, there are numerous variables that affect the energy usage per unit distance. As such, this can lead to inaccuracies in the above-mentioned estimates when relying on previous energy usage data. It is an aim of the present invention to address one or more of the disadvantages associated with the prior art. SUMMARY OF THE INVENTION Aspects and embodiments of the invention provide a control system for controlling a vehicle range estimation system, a system, a vehicle range estimation system, a vehicle, and a method for controlling a vehicle range estimation system as claimed in the appended claims. According to an aspect of the present invention, there is provided a control system for controlling a range estimation system of a vehicle, the control system comprising one or more processors collectively configured to: determine a current range estimate in dependence on the current operating conditions of the vehicle; determine a range disparity value in dependence on the current range estimate and an existing range estimate; and output the range disparity value. In this way, the control system provides the range disparity value which relates to an internal prevailing state of the vehicle and allows a user of the vehicle to take action to change that internal state. The control system can automatically identify the dynamically changing current range estimate and from that determine the range disparity value. The user may then use the range disparity value to guide their actions in operating the vehicle, for example, by changing speed, changing environmental control settings, or the like. Existing range estimates are often based on data accumulated over a longer term, e.g. 1000 km, 10000 km or the like. As the skilled person is aware, many factors can affect the energy consumption of an electric drivetrain, such that a change in one of those variables away from its longer term average can lead to a notable change in the energy consumption and so the expected range. Thus, a current range estimate based on the current operation conditions of the vehicle provides a more short-term view of the range of the vehicle. The current operating conditions may include the current vehicle speed, data from only the current journey, data from a most recent short distance, or other such information. According to an aspect of the invention, there is provided a control system for controlling a vehicle range estimation system of an electric vehicle, the control system comprising one or more processors collectively configured to: receive a speed signal indicative of a current vehicle speed and an energy signal indicative of a currently available battery energy; obtain a first range signal indicative of an expected range for the electric vehicle; determine a current energy consumption in dependence on the speed signal; determine a current range estimate in dependence on the current energy consumption and the energy signal; determine a range disparity value in dependence on the current range estimate and the first range signal, the range disparity value being indicative of a disparity between the expected range and the current range estimate; determine if the range disparity value meets a predetermined condition; and where the range disparity value meets the predetermined condition, output a disparity display signal indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle. In some examples, the disparity indicatorto be displayed to a user of the vehicle may be an audible or haptic output, for example, instead or in combination with a visual output. The current range estimate may be considered to represent the actual range of the electric vehicle based on current operating conditions, while the expected range may be based on previous operating conditions, for example average operating conditions for a vehicle or general operating conditions, such as those of a generic vehicle under test. The expected range value may be determined using longer term data, while the current range estimate is determined using recent or extant conditions, which may be considered short term data. The range disparity value may be considered to indicate a disparity between the expected range and the current range estimate. In this way, the disparity indicator provides information on how the current operating conditions of the vehicle are affecting the range of the vehicle. Having this information allows a user to change the way they are currently operating the vehicle and so change the current range estimate. For example, if the disparity indicator indicated that the current range estimate was less than the expected range, then the user could take steps to reduce the energy consumption of the vehicle or identify a charging station within the current range estimate. Using the speed of the vehicle in determining the range display value is advantageous as it can respond quickly to changes the driver makes to the current operating conditions, while also providing a reasonably stable output, such that the driver is not confused by frequent changes in the disparity indicator. The predetermined condition may be, for example, whether the range disparity value is above a predefined threshold or is between a first value and a second value. The control system may be configured to determine where the range disparity value lies in relation to a plurality of threshold values, to allow more granular classification of the disparity between the expected range and the current range. For example, the control system may be configured to determine if the range disparity value is between a first value and a second value, between the second value and a third value, between the third value and a fourth value, or between the fourth value and a fifth value, where each of the first to fifth values is larger than the previous value. This would provide six classes for the range disparity value - four as defined between the first and fifth values, one below the first value, and one above the fifth value. The disparity display signal may be configured in dependence on the relation of the range disparity value to the one or more threshold values. The control system comprises one or more processors having an electrical input for receiving an input signal; and at least one 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: receive the speed signal indicative of the current vehicle speed and the energy signal indicative of the currently available battery energy; obtain the first range signal indicative of an expected range for the electric vehicle; determine the current energy consumption in dependence on the speed signal; determine the current range estimate in dependence on the current energy consumption and the energy signal; determine the range disparity value in dependence on the current range estimate and the first range signal, the range disparity value being indicative of the disparity between the expected range and the current range estimate; determine if the range disparity value meets the predetermined condition; and where the range disparity value meets the predetermined condition, output the disparity display signal indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle. In an embodiment, the control system is configured to determine the range disparity value by determining a difference between the current range estimate and the first range estimate. This is an efficient manner of identifying a range disparity value. In an example, the range disparity value is determined by subtracting the current range estimate from the expected range. In this way, a negative result indicates that the range of the vehicle is less than the expected range, and a positive result indicates that the range of the vehicle is greater than the expected range. Where the range disparity value is being considered in relation to the predetermined condition, the predetermined condition may include determining whether the range disparity value is greater than or less than zero, for example as a first condition or as an only condition. Optionally, the control system may determine the current energy consumption in dependence on the speed signal using data specific to the vehicle. In this way, the range disparity value will be particularly relevant to each specific vehicle in which a control system according to the disclosure may operate. The data specific to the vehicle may be derived from the historic operation of the vehicle. The data specific to the vehicle may be obtained from another control system within the vehicle. The data specific to the vehicle may be in the form of a look up table. The look up table may relate a current vehicle speed to a current energy consumption, wherein the data therein was derived from historic operation of the vehicle. In an example, the relationship between current energy consumption and current vehicle speed may be based on data comprising an average electrical power usage for each of a plurality of discrete speed ranges, where the average electrical power usage values may be predetermined values. In an embodiment, the control system is configured to determine the current energy consumption in dependence on the speed signal in combination with a time-based average of vehicle energy consumption. The time-based average of vehicle energy consumption takes into account energy consumption other than that linked to the speed of the vehicle. As such, including the time-based average and the speed-based energy consumption may provide a range disparity value with improved accuracy while maintaining the stability provided by the speed-based determination of the current vehicle energy consumption. The two values may be combined according to a predetermined ratio, chosen to provide a useful energy consumption estimate that is both reasonably accurate and reasonably stable. In an example, the average is a rolling average. In an example, the predetermined ratio is 80:20 speed signal to time-based average. Optionally, the control system may obtain the data specific to the vehicle from historic energy consumption data of the vehicle. In this way, the manner in which the vehicle has been operated previously can be used in providing a current range and corresponding range disparity value with improved accuracy. The driving style, journey distance, journey terrain and the like may all vary between vehicles, thus considering data that provides indications of how the vehicle has been previously operated is useful. In an embodiment, the control system may be configured to obtain the data specific to the vehicle from the current journey of the vehicle. In this way, the most recent operating conditions of the vehicle are considered in determining the current energy consumption. Optionally, the control system may output the range disparity value in the disparity display signal. In this way, the disparity indicator may comprise the range disparity value itself, a symbol, or another form of indicator. By varying the disparity indicator according to the range disparity value, the user can identify if any changes they have made to their operation of the vehicle are having an effect on the range of the vehicle. In an embodiment, the control system is configured to determine within which of a plurality of pre-determined boundaries the range disparity value lies, and output a signal indicative of the boundaries in which the disparity value lies, to cause the disparity indicator to comprise a corresponding range disparity symbol of a set of range disparity symbols. In this way, each range disparity symbol of the set of range disparity signals may correspond to one of the plurality of the areas / regions defined by the pre-determined boundaries. Optionally, the plurality of predetermined boundaries may include minorly increased range, majorly increased range, minorly decreased range, majorly decreased range and the corresponding range disparity symbol for each value set comprises, respectively, a first direction symbol, a plurality of the first direction symbol, a second direction symbol in an opposite direction to the first direction symbol, and a plurality of the second direction symbol. In this way, the range disparity symbols provide intuitive feedback to the user on the estimated range of the vehicle and any changes that may occur based on the operation of the vehicle. The range disparity symbols may include arrows, chevrons, triangles, and other such direction symbols. A plurality of the direction symbol may comprise for example a double or triple version of the original direction symbol. As such, an example set of the range disparity symbols may be f, ft, or ►, ► In an embodiment, the set of range disparity symbols comprises a first symbol of a first colour corresponding to predetermined boundaries of range disparity values indicative of an increased range and a second symbol of a second colour corresponding to predetermined boundaries of range disparity values indicative of a decreased range. In this way, the information about range disparity may be conveyed to the user in an intuitive manner. In an example, increased range may be indicated with green while decreased range may be indicated with red. According to yet another aspect of the invention, there is provided a system comprising the control system as described herein and a display device, wherein the display device is configured to receive the disparity display signal and display the disparity indicator in dependence thereon. In this way, the control system and the display device together provide the information to the user and so facilitate the user to take action to alter their operation of the vehicle to try to change the range thereof. According to a further aspect of the invention, there is provided a vehicle range estimation system comprising the control system of any preceding claim; and at least one of: an expected range system configured to provide the first range signal indicative of an expected range for the electric vehicle to the control system; and an energy estimation control system configured to provide historic energy consumption data of the vehicle to the control system. Such a range estimation system can process the available data to facilitate the control system disclosed herein providing the range disparity value and so allow the user to change the operating conditions of the vehicle. Optionally, the expected range system is configured to determine the first range signal by determining a historic energy consumption value according to data specific to the vehicle, the historic energy consumption value being indicative of an energy consumption of the vehicle in a past period of time. In this way, the expected range of the vehicle is based on data specific to the vehicle, and as such the range disparity value is particularly relevant when the current operating conditions of the vehicle differ from operating conditions in a past period of time. The energy consumption of the vehicle in a past period of time may be averaged overtime, may be a rolling average, or other suitable measurement. In an embodiment, the expected range system is configured to determine the first range signal in dependence on a predefined route of the vehicle. Considering the route to be travelled, including for example the road type and incline, is a useful technique for providing an expected range on a journey. Optionally, the energy estimation control system is configured to provide the historic energy consumption data in the form of a predetermined average electrical power usage for each of a plurality of discrete speed ranges. In this way, the current range estimate provided by the control system of the disclosure can have improved accuracy over other range estimating techniques. According to a further aspect of the invention, there is provided a vehicle comprising the control system disclosed herein or the vehicle range estimation system disclosed herein. Such a vehicle can provide a range disparity value, which can be helpful in allowing a user to take action in relation to their journey. According to a yet further aspect of the invention, there is provided a method for controlling a vehicle range estimation system of a vehicle, the method comprising: receiving a speed signal indicative of a current vehicle speed and an energy signal indicative of a currently available battery energy; obtaining a first range signal indicative of an expected range for the electric vehicle; determining a current energy consumption in dependence on the speed signal; determining a current range estimate in dependence on the current energy consumption and the energy signal; determining a range disparity value in dependence on the current range estimate and the first range signal, the range disparity value being indicative of a disparity between the expected range and the current range estimate; determining if the range disparity value meets a predetermined condition; and where the range disparity value meets the predetermined condition, outputting a disparity display signal indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle. In this way, the method allows for providing an indication to a user that the range value provided may be inaccurate. According to an additional aspect of the invention, there are provided computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform a method according to any 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 anyway 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 (a) shows a vehicle in accordance with an embodiment of the invention; Fig. 1(b) shows a block diagram representation of the vehicle according to an embodiment of the invention; Fig. 2 shows a block diagram of a control system according to an embodiment of the invention; Fig. 3 shows a flow chart of a method according to an embodiment of the invention; Fig. 4 shows a block diagram of another control system according to an embodiment of the invention; Fig. 5 shows a flow chart of a further method according to an embodiment of the invention; Fig. 6 shows a flow chart of a method providing energy consumption values linked to vehicle speed values for a specific vehicle for use in determining a current energy consumption in dependence on a speed signal according to an embodiment of the invention; Fig. 7 is a blockdiagram of an embodiment of the vehicle range estimation system according to an embodiment of the invention; and Fig. 8 shows a set of example range disparity symbols according to an embodiment of the invention. DETAILED DESCRIPTION An electric vehicle 100 in accordance with an embodiment of the present invention is described herein with reference to the accompanying Figs. 1 (a) and 1 (b). The vehicle 100 has an electric drivetrain (not shown), and in particular the vehicle 100 may be an electric vehicle, a battery electric vehicle (BEV), or a hybrid vehicle (e.g., a plug-in hybrid vehicle or a mild hybrid vehicle). The vehicle 100 comprises a number of systems and modules, each of which may have an associated control system. The electric drivetrain of the vehicle 100, which may be referred to as a traction motor system, comprises a number of sub-systems and associated control systems, which may be referred to as Electronic Control Units (ECUs). The systems included in the vehicle 100 may include a display control system, a vehicle range estimation system, an energy management system, driving control system, and an energy consumption control system, etc. The electric drivetrain of the vehicle 100 may be a primary or secondary drivetrain for vehicle propulsion. The electric drivetrain includes an electric motor, and may include a plurality thereof, for example two or four electric motors. The electric motor is coupled to one or more drive wheels for propelling the vehicle 100. The electric drivetrain also includes a battery for storing electrical energy, and an inverter for inverting and regulating power received from the battery and outputting it to the electric motor(s) during driving of the vehicle 100. There may be, for example, an inverter for each electric motor or for each pair of electric motors. A sensor may be provided on the inverter. The sensor may be configured to detect an energy usage of the electric drivetrain at the one or more inverters, in particular a tractive energy usage of the electric drivetrain. The sensor may include more than one sensor. In alternative examples, the or each inverter may have an integrated sensor or other means for detecting the energy usage of the one or more inverters, and / or the vehicle 100 may comprise an energy management system configured to determine the energy usage of the electric drivetrain. The detection of the energy usage may comprise calculating a power value from measured voltage and current values, and then integrating the power value over time. It will be appreciated that the sensor may be arranged to detect the tractive energy use of the electric drivetrain, and may not measure energy use for any other energy consumer I element within the vehicle 100. The tractive energy use may be termed the vehicle tractive power consumption. The electric drivetrain may also be referred to as a traction motor system. As shown in Fig. 1 (b), a vehicle range estimation system 102 is installed in the electric vehicle 100. The vehicle range estimation system 102 comprises a control system 200, embodiments of which will be described herein. The vehicle range estimation system 102 may operate according to a method, such as those described herein in relation to Figs. 3 and 5. The vehicle range estimation system 102 may comprise one or both of an expected range system 104 configured to provide a first range signal indicative of an expected range for the electric vehicle 100 to the control system 200, and an energy estimation control system 106 configured to provide historic energy consumption data of the vehicle to the control system, for example speed-related historic consumption data. The energy estimation control system 106 may comprise a look-up table relating speed values to energy consumption. The energy estimation control system 106 is not required to be part of the vehicle range estimation system 102 and may be separate therefrom and be configured to communicate therewith. The expected range system 104 may be configured to determine the first range signal in dependence on long term usage data of the specific vehicle or from similar vehicles. For example, the first range signal may be determined in dependence on data from the previous 700km to 1500km the vehicle has travelled. In an example, the first range signal may be determined in dependence on data from the previous 900km to 1100km, and in a particular example, over the previous 1000km. The expected range system 104 may be configured to determine the first range signal in dependence on a predefined route of the vehicle 100. A user may plan their intended route using a navigation system. The vehicle range estimation system 102 may obtain details of the intended route and can use these details in estimating the vehicle’s range on that route. The vehicle 100 includes a display device 108. The vehicle 100 may additionally include a user input device 110. The display device 108 and / or the user input device 110 may be located in the area of the vehicle’s driver so that the driver can see what is displayed on the display device 108 and can provide an input via the user input device 110. The display device 108 may operate under the control of a display control system (not shown). With reference to Fig. 2, there is illustrated a control system 200 for the vehicle range estimation system 102 of the electric vehicle 100. The control system 200 comprises one or more processors 202. The control system 200 is configured to determine a current range estimate in dependence on the current operating conditions of the vehicle 100. The control system 200 may, for example, determine the current operating conditions in dependence on the sensor for detecting an energy usage of the electric drivetrain and / or an energy management system of the vehicle 100. The control system 200 is configured to determine a range disparity value in dependence on the current range estimate and an existing range estimate. The control system 200 is configured to output an indication of the range disparity value 204. The control system 200 may receive the current operating conditions of the vehicle 100 and / or the existing range estimate via a signal 206. The range disparity value 204 may be used to provide a range disparity indicator to a user of the vehicle, for example via the display device 108. In this way, the user can be informed that the actual range may differ from an indicated expected range. The user may then choose to alter their manner of operation of the electric vehicle if they wish to change the actual range. For example, the user may change the rate or acceleration of the vehicle or the vehicle speed. With reference to Fig. 3, there is illustrated a method 300 for controlling a vehicle range estimation system 102 of an electric vehicle 100. The method 300 may be implemented by the control system 200 described herein in relation to Fig. 2 but is not limited thereto. The method 300 comprises, at block 302, determining a current range estimate in dependence on the current operating conditions of the vehicle 100. At block 304, the method 300 comprises determining a range disparity value in dependence on the current range estimate and an existing range estimate. The method 300 comprises, at block 306, outputting an indication of the range disparity value 204. In relation to the control system 200 of Fig. 2 and the method 300 of Fig. 3, the current energy consumption may be determined in dependence on an indication of a current vehicle speed but is not limited thereto. Other data may be considered in determining the current energy consumption, for example, data from the current journey or from the most recent journey(s) travelled by the vehicle, for example, the most recent 3km or the most recent 30 minutes of driving. The use of current or recent operating conditions may be considered to provide a short-term indication of the range, or a trend of how the range may change. Referring now to Fig. 4, there is shown a block diagram of a control system 400 according to an embodiment of the invention. The control system 400 is suitable for controlling a vehicle range estimation system 102 of an electric vehicle 100. The control system 400 comprises one or more processors, shown for convenience as a single processor 402. The processor 402 is configured to receive a speed signal 404 indicative of a current vehicle speed and an energy signal 406 indicative of a currently available battery energy. The processor 402 is configured to obtain a first range signal 408 indicative of an expected range for the electric vehicle 100. The processor 402 is configured to determine a current energy consumption in dependence on the speed signal 404. The processor 402 is configured to determine a current range estimate in dependence on the current energy consumption and the energy signal 406. The processor 402 is configured to determine a range disparity value in dependence on the current range estimate and the first range signal, the range disparity value being indicative of a disparity between the expected range and the current range estimate. The processor 402 is configured to determine if the range disparity value meets a predetermined condition. The processor 402 is configured to, where the range disparity value meets the predetermined condition, output a disparity display signal 410 indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle 100. The control system 100 as illustrated in Fig. 4 comprises one processor 402, although it will be appreciated that this is merely illustrative. The processor 402 comprises processing means 412 and memory means 414. The processing means 412 may be one or more electronic processing device which operably executes computer-readable instructions. The memory means 414 may be one or more memory device. The memory means 414 is electrically coupled to the processing means 412. The memory means 414 is configured to store instructions, and the processing means 412 is configured to access the memory means 414 and execute the instructions stored thereon. The processor 402 comprises an input means 416 and an output means 418. The input means 416 may comprise an electrical input of the processor 402. The output means 418 may comprise an electrical output of the processor 402. The control system 400 may cooperate with the display device 108 to form a system for informing a user of a change in the expected range. The display device 108 may be configured to receive the disparity display signal and display the disparity indicator in dependence thereon. The input means 416 may be arranged to receive the speed signal 404 and the energy signal 4O6.The output means 418 may be arranged to output the disparity display system. Fig. 5 illustrates a method 500 according to an embodiment of the invention. The method 500 is a method of controlling a vehicle range estimation system 102 of a vehicle 100, such as the vehicle 100 illustrated in Fig. 1 (a) and 1 (b). The method 500 may be performed by the control systems 200, 400 described herein in relation to Figs. 2 and 4, but is not limited thereto. Certain actions of the method 300 described herein in relation to Fig. 3 may correspond to the actions of the method 500 described herein in relation to Fig. 5. At block 502, the method 500 comprises receiving a speed signal indicative of a current vehicle speed and an energy signal indicative of a currently available battery energy. While illustrated as a single block, the reception of the speed signal and energy signal are not required to be simultaneous or otherwise linked together. The method 500 comprises, at block 504, obtaining a first range signal indicative of an expected range for the electric vehicle. At block 506, the method 500 comprises determining a current energy consumption in dependence on the speed signal. The method 500 comprises, at block 508, determining a current range estimate in dependence on the current energy consumption and the energy signal. At block 510, the method 500 comprises determining a range disparity value in dependence on the current range estimate and the first range signal, the range disparity value being indicative of a disparity between the expected range and the current range estimate. The method 500 comprises, at block 512 determining if the range disparity value meets a predetermined condition. At block 514, the method 500 comprises, where the range disparity value meets the predetermined condition, outputting a disparity display signal indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle 100. The speed signal 404 and the energy signal 406 may be received from other systems within the vehicle 100, such as, for example, a traction motor system and energy management system respectively. The speed signal 404 may be received from a vehicle speed sensor, which may be part of the traction motor system. The vehicle speed sensor may measure, or derive its measurement from, a wheel speed of the vehicle. The energy signal 406 may be derived from a power value calculated from measured voltage and current values, and then integrated overtime The first range signal 408 may be received from another element of the vehicle range estimation system 102, such as the expected range system 104, from another system of the electric vehicle 100, or may be determined by the control system 400 itself. The control system 400 may receive historic energy consumption data, in particular speed-related historic energy consumption data, of the vehicle from the energy estimation control system 106. The expected range may be based on, for example, previous operating conditions of the vehicle or general operating conditions of a group of similar vehicles. This may involve consideration of the energy used in relation to the distance travelled or the energy used in relation to the journey time. The expected range may be derived from data gathered over a relatively long period of time such as 15 to 30 journey hours or over a relatively long distance, such as 800km to 1500km. Energy consumption for use in the determination of the expected range may be determined over short intervals and then averaged over a larger interval. The shorter interval may be less than 10km, for example 3km, and the larger interval may be over 500km, for example 1000km. For each short interval, the power consumption may be integrated over the distance and then divided by the distance to provide an average energy consumption forthat short interval. Then a rolling average may be calculated to provide an average energy consumption for the longer distance. In an example, the larger interval is 1000km, and the rolling average energy consumption may be calculated according to: NewlOOOkmAve = Prevl000kmAve*997 / 1000 + 3kmAve*3 / 1000, where NewlOOOkmAve is the new average value for the energy consumption over 1000km; Prevl OOOkmAve is the previous average value for the energy consumption over 1000km; and 3kmAve is the value for the most recent 3km travelled by the vehicle. This average energy consumption, NewlOOOkmAve, can then be divided into the available battery energy to provide an expected range value. The power consumption may be determined from measured current and voltage values from the battery. Consider an example where the available battery energy is 100kWh and an average consumption of 0.2kWh / km over a distance of 1000km has been determined. This would yield an expected range of 100 / 0.2 = 500km. In an example, the previous operating conditions of the vehicle comprise significant / predominantly city-type driving, including short journeys, lower speeds, and frequent stop-starts. If such a vehicle then began a longdistance journey, at higher speeds with fewer stop-starts, its energy usage would be significantly different to that of its recent journeys. Thus, where the expected range is based on previous operating conditions, the expected range would be inaccurate forthe current journey. Similarly, if the expected range is based on general operating condition, derived from a combination of different types of journeys, then the expected range could be inaccurate for both city-type driving and long-distance driving. Consider a further example, similar to that discussed above in the previous paragraph, where the available battery energy is 100kWh and an average consumption of 0.2kWh / km over a distance of 1000km has been determined, giving an expected range of 500km. However, according to the teachings herein, a current energy consumption has been determined as 0.21 kWh / km which would yield a current range estimate of 100 / 0.21 = 476km. The range disparity value may be considered to indicate a disparity between the current range estimate based on the vehicle’s current operating conditions and the expected range. In this way, the range disparity value provides information on how the current operating conditions of the vehicle are affecting the range of the vehicle. Providing this information to a user allows them to modify their behaviour or plans so as to adapt to the change in the range and perhaps reduce or increase the disparity as required. For example, they may adjust the way they are currently operating the vehicle and so change the current range estimate. In an example where the range disparity value indicated that the current range estimate was less than the expected range, then the user could take steps to reduce the energy consumption of the vehicle, identify a charging station within the current range estimate, or the like. The range disparity value may be considered as a measure of how a range based on operating conditions of the vehicle over the long term differ from a range based on operating conditions in the short term. The processor 402 may be configured to determine the range disparity value by determining a difference between the current range estimate and the first range estimate. Other methods of determining a disparity between the estimates, such as percentage, ratio or the like will be apparent to the skilled person. The control system 200, 400 may be configured to determine the current energy consumption in dependence on the short-term or current operating conditions of vehicle. The current energy consumption may be determined by considering a subset of the data indicating the current or short-term operating conditions of the vehicle. In one example, the current speed of the vehicle is used to provide an indication of the current energy consumption. In another example, an indication of the current energy consumption may be derived from an energy usage signal which is indicative of the electrical power usage of the electric drivetrain during driving of the vehicle. From this energy usage signal, an average of electrical power usage may be used as the indication of the current energy consumption. The average may be taken over a period of time to provide a time-based average of vehicle energy consumption. In other examples of the use of the energy usage signal, the current energy consumption may be derived using the energy usage signal over the present journey, and / or over the most recent travels of the vehicle e.g. over the most recent distance of a predefined length. The processor 402 may be configured to determine the current energy consumption in dependence on the speed signal 404. The processor 402 may be configured to determine the current energy consumption in dependence on the speed signal 404 by using a look-up table or similar, where a current energy consumption value is provided for each vehicle speed value, or for ranges ofvehicle speed values, e.g. for 20 kph to 30kph, 30 kph to 40 kph, 40 kph to 50 kph and so on. In an example, an average electrical power usage may be provided for each of a plurality of discrete speed ranges. Determining the current energy consumption in dependence on the speed signal 404 may be based on general data applying to the class ofvehicle. Such general data may be obtained by manufacturer vehicle testing (e.g., prior to sale of the vehicle or testing on a similar or identical vehicle, e.g., on a dyno), by modelling, and / or based on data from identical or similar vehicles already in use, such as a fleet of identical or similar vehicles. Additionally or alternatively, data applying to the specific vehicle may be used. Using data for the specific vehicle allows any variations in the vehicle configuration, such as wheel size, tyre type, roof bars or the like to be considered. The data applying to the specific vehicle may link vehicle speed values to the energy used by that specific vehicle at those speeds. In this way, the control system may access or store historic energy consumption data of the vehicle. Where data specific to the vehicle is to be used, the control system 400 may determine the current energy consumption in dependence on the speed signal itself, in combination with the energy estimation control system 106, or may obtain the current energy consumption from the energy estimation control system 106. While the energy consumption control system 106 may be part of the vehicle range estimation system 102 according to the disclosure, for example as part of the control system 200, 400, or separate therefrom, it will be understood that it may be separate from the vehicle range estimation system 102 and may, for example, be part of the traction motor system. An example of providing energy consumption values linked to vehicle speed values for the specific vehicle, which may be part of determining 506 a current energy consumption in dependence on the speed signal will now be described in relation to Fig. 6 and Fig. 7. Fig. 6 is a flow diagram of a method of 5050 of providing updated energy consumption values linked to vehicle speed values. Fig, 7 is a block diagram of an embodiment of the vehicle range estimation system 102 illustrated in Fig. 1(b). The vehicle range estimation system 102 comprises the control system 400, the expected range system 104 and the energy estimation control system 106. The energy estimation control system 106 may be configured to provide the historic energy consumption data in the form of an average electrical power usage for each of a plurality of discrete speed ranges. At block 5052, a predetermined average electrical power usage for each of a plurality of discrete speed ranges is stored. The predetermined average electrical power usage for each of the discrete speed ranges may correspond to the general data discussed above, and as such, may be derived from testing, modelling, fleet data and so on. The predetermined average electrical power usages for each of the discrete speed ranges may thereby provide an estimate of the actual energy usage of the vehicle 100 when driving at a certain speed. The predetermined average electrical power usages may be stored in units of Wh / km. At block 5054, an energy usage signal 1020 indicative of an electrical power usage of the electric drivetrain during driving of the vehicle is received. The energy usage signal 1020 may be indicative of a tractive power consumption. For example, the energy usage signal 1020 may be received from a sensor (not shown) arranged to detect the energy usage of the electric drivetrain, or the energy usage signal 1020 may be received from another part of the vehicle 100, for example an energy management system. In examples, the energy usage signal 1020 is an instantaneous power usage of the electric drivetrain, in particular of the inverters. In particular, the energy usage signal 1020 may be indicative of the instantaneous power usage of the electric drivetrain in units of kW. The energy usage signal 1020 may be received, for example, by the vehicle range estimation system 102 at a sampling rate of between 100Hz and 10Hz. The energy consumption control system 106 may be configured to convert the energy usage signal 1020 into an energy usage per unit distance, in particular in units of Wh / km. At block 5066, a signal 1022 indicative of a corresponding vehicle speed of the vehicle 100 is received. The signal 1022 indicative of a corresponding vehicle speed may be the same as the speed signal 404. The signal 1022 may be received from a vehicle speed sensor or from another part of the vehicle 100, for example a driving control system. The signal 1022 may be received at the same sampling rate as the energy usage signal 1020. The signal 1022 is indicative of the vehicle speed in units of km / h. At block 5058, the stored predetermined average electrical power usage for each of the plurality of discrete speed ranges are updated based on the received signals 1020, 1022 indicative of the electrical power usage and the vehicle speed to provide the moving average electrical power usages. In this way, the moving average electrical power usages are based on the actual use of the vehicle, and thus are adapted to the configuration of the vehicle. In examples of determining the current energy consumption in dependence on the speed signal 404 based on data for the specific vehicle, each of the moving average electrical power usages may be a simple moving average, a cumulative moving average, a weighted moving average, an exponentially weighted moving average, or the like. In examples, each of the discrete speed ranges may be equal in size (in terms of the range of speed covered). For example, each of the discrete speed ranges may be between 10 km / h and 30 km / h. In other examples, the size of each of the discrete speed ranges may be different. In one example, the first discrete speed range may be Okm / h to 10km / h, the second discrete speed range may be 10km / h to 30km / h, the third discrete speed range may be 30km / h to 60km / h, the fourth discrete speed range may be 60km / h to 100km / h, the fifth discrete speed range may be 100km / h to 140km / h, the sixth discrete speed range may be 140km / h to 160km / h, and the seventh discrete speed range may be 160km / h to 240km / h. It will be appreciated that some of the discrete speed ranges will be updated from the predetermined average electrical power usage to the moving average electrical power usage sooner than others because the vehicle 100 will likely not be driven for equal amounts of time within all of the discrete speed ranges. Accordingly, each of the discrete speed ranges may be individually updated from the predetermined average electrical power usage to the moving average electrical power usage. A discrete speed range may be updated to the moving average electrical power usage once the number of applicable data points in that discrete speed range has reached a threshold. In this way, after the vehicle 100 has been used for an initial period of time, one or more of the average energy usages correspond to historic energy consumption data of the vehicle 100. The processor 402 may be configured to determine the current energy consumption in dependence on the speed signal in combination with other data. When considering other data in determining the current energy consumption, that other data may also be specific to the vehicle, or non-vehicle specific data. The data specific to the vehicle may be historic energy consumption data of the vehicle. The data specific to the vehicle may be based on the current journey only, a predefined most recent distance, e.g. the most recent 20km, the most recent 10km, the most recent 5km, the most recent 3 km, or another suitable distance. The data specific to the vehicle may comprise an average of vehicle energy consumption, such as a time-based average or a distancebased average. The processor 402 may be configured to determine the current energy consumption in dependence on the speed signal 404 in combination with a time-based average of vehicle energy consumption. A first value for the current energy consumption may be obtained based on the speed signal, for example according to the description above. A second value for the current energy consumption may be determined based on a timebase average of vehicle energy consumption. The first value and the second value can then be combined to provide a modified value for the current energy consumption. The time-based average of vehicle energy consumption may be determined from the energy usage signal 406 which is indicative of the electrical power usage of the electric drivetrain during driving of the vehicle. The energy usage signal 406 may be sampled repeatedly and the sampled values then averaged. The time-based average of vehicle energy consumption may be determined by the energy consumption control system discussed herein or by another suitable system within the vehicle 100. The first value and the second value may be combined in any suitable manner, however, in an example, they may be combined in a ratio of 80:20 of first value to second value. The inventors have identified this combination as providing an output that has a useful value of accuracy, stability, and reactiveness to user actions. The processor 402 is configured to determine if the range disparity value meets a predetermined condition. The predetermined condition allows for determining if the user should be made aware of the range disparity. The predetermined condition may be, for example, whether the range disparity value is above a predefined threshold or is between a first value and a second value. The control system may be configured to determine where the range disparity value lies in relation to a plurality of threshold values, to allow more granular classification of the disparity between the expected range and the current range. For example, the control system may be configured to determine if the range disparity value is between a first value and a second value, between the second value and a third value, between the third value and a fourth value, or between the fourth value and a fifth value, where each of the first to fifth values is larger than the previous value. This would provide six classes for the range disparity value - four as defined between the first and fifth value, one below the first value and one above the fifth value. The disparity display signal may be configured in dependence on the relation of the range disparity value to the one or more threshold values. Where the range disparity value meets the predetermined condition, the processor 402 is configured to output a disparity display signal indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle. The disparity display signal may include the range disparity value and not merely that the range disparity value meets the predetermined condition. The disparity indicator may comprise a symbol, a change in an existing item on the display, the range disparity value itself, or another form of indicator. The disparity indicator may vary according to the range disparity value. This allows more granular information to be provided to the user in relation to the status and operation of the vehicle. The processor 402 is configured to determine within which of a plurality of pre-determined boundaries the range disparity value lies, and output a signal indicative of the boundaries in which the disparity value lies, to cause the disparity indicator to comprise a corresponding range disparity symbol of a set of range disparity symbols. The plurality of pre-determined boundaries may be considered as sets of possible range disparity values, wherein the determined range disparity value will lie within one of the predetermined boundaries or sets. Each boundary may have a symbol assigned thereto, such that when the range disparity value lies within a particular boundary, the disparity indicator will be the symbol assigned to that boundary. The plurality of predetermined boundaries may include minorly increased range, majorly increased range, minorly decreased range, majorly decreased range and the corresponding range disparity symbol for each value set comprises, respectively, a first direction symbol, a plurality of the first direction symbol, a second direction symbol in an opposite direction to the first direction symbol, and a plurality of the second direction symbol. Direction symbols are those which indicate a direction, e.g. up, down, greater, lesser, etc. The range disparity symbols may include arrows, chevrons, triangles, and other such direction symbols. A plurality of the direction symbol may comprise for example a double ortriple version of the original direction symbol. As such, an example set of the range disparity symbols may be f, ft, |, || or ►, ► ►, ◄, Referring to Fig. 8, there is shown an example set of range disparity symbols according to an embodiment of the invention. The example set is indicated generally by the reference numeral 600 and is based on chevrons. The range disparity symbol for a decreased range comprises a downward pointing chevron, indicated by the reference numeral 602. The range disparity symbol for a significantly decreased range comprises a pair of downward pointing chevrons, indicated by the reference numeral 604. The pair of downward chevrons 604 are positioned one above the other such that the upper chevron is partially nested within the lower chevron. The range disparity symbol for an increased range comprises an upward pointing chevron, indicated by the reference numeral 606. The range disparity symbol for a significantly increased range comprises a pair of upward pointing chevrons, indicated by the reference numeral 608. The pair of downward chevrons 608 are positioned one above the other such that the upper chevron is partially nested within the lower chevron. Colour may also be used as part of the disparity indicator, for example combined with an existing item on the vehicle display. For example, a decreased range may be indicated by turning the estimated range value red, while an increased range may be indicated by turning the estimated range green. The set of range disparity symbols 600 may comprise a first symbol of a first colour corresponding to said predetermined boundaries of range disparity values indicative of increased range and a second symbol of a second colour corresponding to predetermined boundaries of range disparity values indicative of a decreased range. Again, in this example, green may be used to indicate increased range and red may be used to indicated decreased range. The methods described herein may be implemented by computer readable instructions which, when executed by one or more processors, cause the one or more processors to perform the methods. The computer readable instructions may be stored on a memory associated with the one or more processors. The systems and methods of the disclosure provide a range disparity value, which in turn is used to provide a disparity indicator for display to the driver of the vehicle. This allows the driver to be informed that the actual range of the vehicle based on current operating conditions may differ from the expected range. The user may then choose to alter their manner of operation of the electric vehicle if they wish to change the actual range. For example, the user may change the vehicle speed or adjust the vehicle’s environmental controls. The disclosure teaches a number of ways of using the current operating conditions to derive a current energy consumption value for the vehicle. The disparity indicator may be considered to provide an indication to the driver of a trend in the expected range, i.e. based on current operating conditions the expected range is likely to trend up or trend down. The disparity indicator may be considered to provide an indication of how a range estimated based on short term data (e.g. the current journey, the most recent 3km, or the like) compares to a range estimated on long term data. 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.

Claims

1. A control system for controlling a vehicle range estimation system of an electric vehicle, the control system comprising one or more processors collectively configured to:receive a speed signal indicative of a current vehicle speed and an energy signal indicative of a currently available battery energy;obtain a first range signal indicative of an expected range for the electric vehicle;determine a current energy consumption in dependence on the speed signal;determine a current range estimate in dependence on the current energy consumption and the energy signal;determine a range disparity value in dependence on the current range estimate and the first range signal, the range disparity value being indicative of a disparity between the expected range and the current range estimate;determine if the range disparity value meets a predetermined condition; andwhere the range disparity value meets the predetermined condition, output a disparity display signal indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle.

2. A control system as claimed in claim 1 configured to determine the range disparity value by determining a difference between the current range estimate and the first range estimate.

3. A control system as claimed in any preceding claim wherein the one or more processors are configured to determine the current energy consumption in dependence on the speed signal using data specific to the vehicle.

4. A control system as claimed in claim 3 wherein the one or more processors are configured to determine the current energy consumption in dependence on the speed signal in combination with a timebased average of vehicle energy consumption.

5. A control system as claimed in claim 4 wherein the one or more processors are configured to obtain the data specific to the vehicle from historic energy consumption data of the vehicle.

6. A control system as claimed in any preceding claim wherein the one or more processors are configured to determine within which of a plurality of pre-determined boundaries the range disparity value lies, and output a signal indicative of the boundaries in which the disparity value lies, to cause the disparity indicator to comprise a corresponding range disparity symbol of a set of range disparity symbols.

7. A control system as claimed in claim 6 wherein the plurality of predetermined boundaries include minorly increased range, majorly increased range, minorly decreased range, majorly decreased range and the corresponding range disparity symbol for each value set comprises, respectively, a first direction symbol, a plurality of the first direction symbol, a second direction symbol in an opposite direction to the first direction symbol, and a plurality of the second direction symbol.

8. A control system as claimed in claim 6 or 7 wherein the set of range disparity symbols comprises a first symbol of a first colour corresponding to predetermined boundaries of range disparity values indicative of increased range and a second symbol of a second colour corresponding to predetermined boundaries of range disparity values indicative of a decreased range.

9. A system comprising the control system of any preceding claim and a display device wherein the display device is configured to receive the disparity display signal and display the disparity indicator in dependence thereon.

10. A vehicle range estimation system comprisingthe control system of any preceding claim; and at least one ofan expected range system configured to provide the first range signal indicative of an expected range for the electric vehicle to the control system; andan energy estimation control system configured to provide historic energy consumption data of the vehicle to the control system.

11. A vehicle range estimation system as claimed in claim 10 wherein the expected range system is configured to determine the first range signal by determining a historic energy consumption value according to data specific to the vehicle, the historic energy consumption value being indicative of an energy consumption of the vehicle in a past period of time.

12. A vehicle range estimation system as claimed in claim 10 or 11 wherein the expected range system is configured to determine the first range signal in dependence on a predefined route of the vehicle.

13. A vehicle range estimation system as claimed in any of claims 10 to 12 wherein the energy estimation control system is configured to provide the historic energy consumption data in the form of a predetermined average electrical power usage for each of a plurality of discrete speed ranges.

14. A vehicle comprising the vehicle range estimation system of any of claims 8 to 11 or the control system of claims 1 to 7.

15. A method for controlling a vehicle range estimation system of a vehicle, the method comprising: receiving a speed signal indicative of a current vehicle speed and an energy signal indicative of a currently available battery energy;obtaining a first range signal indicative of an expected range for the electric vehicle; determining a current energy consumption in dependence on the speed signal;determining a current range estimate in dependence on the current energy consumption and the energy signal;determining a range disparity value in dependence on the current range estimate and the first range signal, the range disparity value being indicative of a disparity between the expected range and the current range estimate;determining if the range disparity value meets a predetermined condition; andwhere the range disparity value meets the predetermined condition, outputting a disparity display signal indicative thereof, to cause a disparity indicator to be displayed to a user of the vehicle.s

Images