GB2505665A

GB2505665A - Residual range display

Info

Publication number: GB2505665A
Application number: GB1215899.4A
Authority: GB
Inventors: Duncan Robertson; Tom Wellings
Original assignee: Jaguar Land Rover Ltd
Current assignee: Jaguar Land Rover Ltd
Priority date: 2012-09-06
Filing date: 2012-09-06
Publication date: 2014-03-12
Anticipated expiration: 2032-09-06
Also published as: GB201215899D0; GB2505665B

Abstract

A residual range system for a motor vehicle having an electric drive motor and an energy storage device 3 has a processor that calculates a residual range rate of change (ROC) that is output for display. The processor may also calculate a residual range RV indicating a distance that the vehicle can travel based on the available energy in the energy storage device. The processor can calculate a state of charge (SOC) of an energy storage device and its rate of change, which is output to a display. The rate of change indication of the residual range may be calculated over a time interval and classified according to a threshold determined from a look-up table. The residual range and its rate of change may be calculated from the state of charge of the storage device and based upon vehicle parameters such as acceleration, deceleration, speed and electrical system status. The residual range rate of change may be displayed as a graphical element that can represent variations by its length, width, size, shape, colour, orientation and profile and by a marker travelling along a residual range scale whose position indicates an increase or decrease in remaining range.

Description

RESIDUAL RANGE SYSTEM

TECHNICAL FIELD

The present invention relates to a residual range system for a motor vehicle; and a method of calculating a residual range. Aspects of the invention relate to an apparatus, to a system, to a range indicator, to a method and to a vehicle.

BACKGROUND OF THE INVENTION

The residual range (i.e. the distance the vehicle can travel) of current electric vehicles is typically displayed to the driver as a specific range estimate in either kilometres or miles. In some vehicles, the state of charge (SOC) of the battery is displayed and the driver must estimate the residual range for themselves. However, there are a range of factors which influence the residual range of the vehicle, including driving style, road type, traffic levels, road gradient, external temperature and parasitic in-car electrical features. These factors can result in a high degree of volatility in the predicted residual range which can affect the driver's confidence in the estimated residual range and contribute to so-called range anxiety'.

The problems associated with prior art arrangements can be exacerbated when the residual range is displayed as a discrete value and the driver is not provided with an indication of how the residual range is changing. For example, when the vehicle is stationary in traffic the driver may not appreciate that the residual range is largely unaffected as, unlike an internal combustion engine, the drive motor is not operating.

At least in certain embodiments, the present invention sets out to overcome or ameliorate at least some of the problems associated with prior art systems.

SUMMARY OF THE INVENTION

Aspects of the present invention relate to a residual range system for a motor vehicle; and a method of calculating a residual range.

In a further aspect, the present invention relates to an apparatus for a motor vehicle comprising an electric drive motor and an energy storage device, the apparatus comprising: a processor configured to calculate a residual range rate of change (ROC) indicator and to output the residual range FlOG indicator for display. The apparatus may comprise a residual range system or a part thereof.

The residual range ROC indicator can provide a driver with an indication of how their current driving style and/or the vehicle operating systems are influencing the residual range of the vehicle.

The processor can be configured to calculate the residual range P00 indicator continuously or over one or more pre-defined time interval. The processor can calculate an average residual range P00 indicator over a plurality of said pre-defined time intervals.

The processor can output a direct indication of the ROC of the residual range, for example by displaying a numerical value corresponding to the residual range ROC indicator.

Alternatively, the processor can classify the residual range ROC indicator relative to at least one threshold. The at least one threshold can be pre-defined. The processor can, for example, classify the residual range P00 indicator with reference to one or more pre-defined bands defined by an upper and a lower threshold. To classify the residual range P00 indicator, the processor can access a look-up table stored in a memory device.

The processor can further be configured to calculate a residual range indicative of a distance that the vehicle is capable of travelling based on the available energy in said energy storage device. The processor can be configured to output the calculated residual range for display.

The processor can be configured to calculate the residual range based on a state of charge (SOC) of the energy storage device. The residual range P00 indicator could be determined from the calculated residual range or from the state of charge (SOC) of the energy storage device. In addition, or alternatively, the processor can calculate the residual range and/or the residual range ROC indicator based on one or more vehicle operating parameters, such as acceleration, deceleration, vehicle speed and electrical system status.

A display device can be provided for displaying said residual range P00 indicator. The display device can display the residual range ROC indicator by displaying a dial, a gauge or a graph. Alternatively, the display device can display the residual range P00 indicator by displaying a graphical element. The display device can represent variations in the residual range P00 indicator by altering one or more of the following characteristics of the graphical element: length, width, size, shape, colour, orientation and profile. The graphical element could be a line, a polygon (such as a triangle or a rectangle) or an animated symbol.

The graphical element could be displayed in a fixed position. Alternatively, the graphical element can travel along a scale indicating the calculated residual range.

The graphical element can be displayed together with a marker indicating the calculated residual range. Alternatively, the graphical element can comprise a marker indicating the calculated residual range. The position of the marker in relation to a remainder of the graphical element is indicative of an increase or a decrease in the residual range.

In a further aspect, the present invention relates to a method of indicating a residual range of a motor vehicle having an electric drive motor and an energy storage device, the method comprising the following steps: calculating a residual range ROC indicator; and outputting the calculated residual range ROC indicator to a display device.

The method can further comprise the step of calculating a residual range indicative of a distance that the vehicle is capable of travelling based on the available energy in said energy storage device. The residual range can also be output to the display device.

In a still further aspect, the present invention relates to a state of charge system for an energy storage device, the system comprising: a processor configured to calculate a state of charge of the energy storage device and a rate of change (flOG) of the state of charge; and a display device for displaying said calculated ROC.

In a yet further aspect, the present invention relates to a method of indicating a state of charge of an energy storage device, the method comprising the following steps: calculating a state of charge of said energy storage device; calculating a rate of change (flOG) of the state of charge of said energy storage device; and outputting the calculated ROC to a display.

The energy storage device can be an accumulator for storing energy. The energy storage device can be an electrical battery for electrochemical energy storage (for example a storage battery); a capacitor for storing energy in an electrical field; or a mechanical accumulator for storing mechanical energy (for example a flywheel).

The present invention also relates to a vehicle comprising a residual range system or a state of charge system as 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. For example, features described with reference to one embodiment are applicable to all embodiments, unless such features are incompatible.

BRIEF DESCRIPTION OF THE DRAWINGS

One or more embodiments of the present invention will now be described, by way of example only, with reference to the accompanying figures, in which: Figure 1 shows a schematic representation of a residual range system in accordance with an embodiment of the present invention; and Figures 2a-e illustrate a display arrangement for the residual range system according to an embodiment of the present invention.

DETAILED DESCRIPTION

An embodiment of a residual range system 1 according to the present invention will now be described with reference to Figures 1 and 2. The residual range system 1 is for use in an electric vehicle (not shown) having an electric drive motor and a storage battery 3. The residual range system 1 displays a residual range estimate R for the vehicle based on the available energy in the storage battery 3. The storage battery 3 in the present embodiment is an electrical battery for converting stored chemical energy into electrical energy to power the electric drive motor. As described herein, the residual range system 1 also provides a graphical representation of a residual range rate of change (ROC) indicator.

As shown in Figure 1, the residual range system 1 comprises a microprocessor 5 having a range calculating module 7, a driving assessment module 9 and a ROC module 11. The driving assessment module 9 evaluates a driving style of a driver D and generates an economy indicator value which is output to the range calculating module 7. The economy indicator value is based on measured inputs from vehicle controls 13 (such as an accelerator pedal 15, a brake pedal 17 and a steering wheel 19) and other vehicle systems 21, such as lateral and longitudinal accelerometers. The driving style can be evaluated with reference to the rate of acceleration and/or braking; and the speed at which the vehicle is being driven. A suitable technique for evaluating driving style and generating an economy indicator value is known from the Applicant's co-pending application, application number GB 1200283 filed on 9 January 2012, the contents of which are incorporated herein in their entirety by reference.

The range calculating module 7 calculates the residual range estimate R based on system s operating data received from a plurality of vehicle systems. In the present embodiment, the range calculating module 7 communicates with a thermometer 23 to obtain external temperature data (which can affect the operating efficiency of the storage battery 3); and a vehicle CAN bus 25 to obtain status information of vehicle systems (particularly vehicle electrical systems, such as climate control, infotainment systems, etc.). The range calculating module 7 can also be configured to communicate with a satellite navigation system 27 to obtain journey route data relating to the journey on which the vehicle is travelling (for example based on pie-programmed journey data or a predicted route for the vehicle derived from historic data). For a particular route, the satellite navigation system 27 can provide route data relating to one or more of the following: gradient, altitude (increases/decreases), and road type data. The range calculating module 7 can also receive system inputs 29 from other vehicle systems, for example to determine vehicle loading and/or parasitic load data.

The storage battery 3 comprises an array of cells (not shown) connected in parallel within branches which are in turn arranged in series. The cells in the present arrangement are lithium ion (Li÷) cells, but other types of cells could be employed. A battery monitoring system 31 is coupled to the storage battery 3 to calculate an actual battery Soc based on the operating voltage and cell temperature within the storage battery 3. The SOC is an indication of the available energy stored in the storage battery 3 and an SOC value (ActualBatterySOC) is output to the range calculating module 7.

The range calculating module 7 calculates the residual range estimate R using the following equation: Act'nWatterySOC Rc'npe ie( ) =f Where kM'h/km = (No?ntuiVaIug). C1.C,. C A nominal value (Nominal Value) of the electrical energy required to propel the vehicle one kilometre is modified by applying correction values (C1, C2, Ce... C) associated with each vehicle system (i.e. the thermometer 23, the vehicle CAN bus 25 and the satellite navigation system 27) and also the economy indicator value output from the driving assessment module 9. The correction values (C1, C2, Ce... C) for each vehicle system and for the economy indicator value are selected from a look-up table stored in the memory device 21.

Accordingly, different weightings can be applied to the various vehicle systems. The look-up table contains y correction values «=1 (e.g. 1, 0.9, 0.8, 0.7, etc.) and z correction values »=1 (e.g. 1, 1.1, 1.2, 1.3, etc.).

The range calculating module 7 outputs the residual range estimate R, to a digital display 33 provided in an instrument cluster 35. The digital display 33 has a display processor 37 configured to display the residual range estimate R as a marker 39 on an elongate gauge 41. The illustrated elongate gauge 41 shows a percentage residual range estimate R ranging from 0% to 100%. In the present embodiment, the marker 39 is a vertical bar and the position of the marker 39 on the elongate gauge 41 indicates the residual range estimate 11v A numerical value 43 corresponding to the residual range estimate 11v is optionally displayed alongside the marker 39.

The ROC of the SOC is indicative of the ROC of the residual range estimate R. The ROC module 11 monitors the actual battery SOC (calculated by the battery monitoring system 31) and calculates the average ROC of the SOC over a pre-defined time period:

SOC

$t'erage Rum of change) = where n = number of sample intervals The change in the SOC at any given time (t) is calculated by the following equation: (Chcn9e in SOC) = [3attervSOC -Butt ErVSOCN).

where t= time and x = sample interval The ROC module 11 outputs the average ROC of the SOC to the display processor provided in the digital display 33. As described in more detail below, the display processor is configured to select a graphical element 45 to represent the ROC of the residual range R based on the average ROC of the SOC. The display processor renders the selected graphical element 45 on the longitudinal axis X with the marker 39.

In the present embodiment, the graphical element 45 is a truncated isosceles triangle having a graded fill. The base of the triangle is arranged coincident with the marker 39 and the top of the triangle points in the opposite direction to the direction of travel of the marker 39 to represent a comet tail' extending behind the marker 39. The graphical elements 45 for selection by the display processor have different heights indicative of different rates of change of the residual range R. Specifically, a high ROC of the residual range R is represented by a triangle having a relatively large height (as shown in Figure 2a); and a low ROC of the residual range R is represented by a triangle having a relatively small height (as shown in Figure 2c). The height of the triangle can be modified to represent an intermediate ROC of the iesidual iange R (as shown in Figure 2b). It will be appreciated that the ROC can be relatively high when the residual range is low (as shown in Figure 2d); or relatively low when the residual range is high (as shown in Figure 2e). If the ROC of the residual range R is zero, the graphical element 45 is not displayed.

The orientation of the graphical element 45 in relation to the marker 39 also indicates whether the residual range R is increasing (indicating that the storage battery 3 is being charged, for example when the vehicle is connected to a charging station or when recovering energy under braking) or decreasing (indicating that the storage battery 3 is being discharged, for example by operating the electric motor). The graphical element 45 can be displayed on a first side of the marker 39 to represent a positive ROC; and on a second side of the marker 39 to represent a negative P00.

The display processor 37 references a look-up table stored in a memory device 45 to select the graphical element 45 for display. The look-up table comprises a plurality of pre-defined bands (defined by upper and lower thresholds) relating to the calculated average ROC of the SOC. A specific version (Graphic#1, Graphic#2... Graphic#n) of the graphical element 45 is associated with each of said bands in the look-up table. The display processor receives the calculated average ROC of the SOC and references the look-up table to identify the appropriate version of the graphical element 45 to be displayed. The display processor 37 renders the selected graphical element 45 alongside the marker 39 to represent the ROC of the residual range R. A sample look-up table for reference by the display processor is shown below as Table A. Average ROC Display 0% -0.25% Graphic#1 0.26% -0.5% Graphic#2 0.51% -0.75% Graphic#3 0.76% -1.0% Graphic#4 1.01%-1.25% Graphic#5 Etc Etc

TABLE A

The operation of the residual range system 1 will now be described. The driving assessment module 9 evaluates the driving style of the driver D and outputs the economy indicator value to the range calculating module 7. The economy indicator value and the system operating data (received from the thermometer 23, vehicle CAN bus 25 and satellite navigation system 27) are used to select correction values (C1, C2, C3... Cr). A nominal value of the electrical energy required to propel the vehicle a predefined distance (kWh/km) is modified by applying the selected correction values (C1, C2, C3... C) to estimate the electrical energy required to propel the vehicle one kilometre (kWh/km). The range estimate R is then calculated using the actual SOC value of the storage battery 3 calculated by the battery monitoring system 31 (with reference to the measured operating temperature and voltage of the storage battery 3).

The range estimate R is output by the range calculating module 7 to the digital display 33 and displayed as the marker 39.

The ROC module 11 monitors the SOC value of the storage battery 3 and calculates the average ROC of the SOC over a pre-defined period of time. The display processor references the look-up table to select the version of the graphical element 45 associated with the calculated average ROC of the SOC. The selected graphical element 45 is then displayed together with the marker 39 (and optionally also the numerical value 41) to indicate the ROC of the residual range estimate R. The driver D can thereby determine the rate at which the residual range estimate R is changing. Accordingly, the driver D can adapt their driving style based on the ROC of the residual range estimate R, for example to extend the residual range of the vehicle.

The present invention has been described with reference to an electric vehicle (EV) having an electric drive motor and storage battery. The invention could be embodied in a hybrid electric vehicle (HEV) or a range extender vehicle in which an internal combustion engine is used in conjunction with an electric drive motor. Indeed, the concept of displaying the ROC of the residual range of the vehicle could be implemented in a vehicle driven by an internal combustion engine.

S

Although the graphical element 45 has been described as a triangular device, it could take other forms to represent the ROC. Moreover, the graphical element 45 could be modified dynamically. For example, the display processor could implement an algorithm to determine the size, shape and/or colour of the graphical element 45 in response to changes in the calculated average ROC of the Soc. It will be appreciated that various changes and modifications can be made to the embodiment described herein without departing from the scope of the present invention.

The residual range system 1 according to the present invention could be used to indicate a change in the SOC of the storage battery 3 since the vehicle was last used. For example, when the vehicle is switched on, the marker 39 and/or the graphical element 45 could travel along the elongate gauge 41 to indicate the change in the soc of the storage battery 3.

This arrangement could be used to indicate a change in the SOC of the storage battery 3.

The SOC could increase between uses, for example following charging of the storage battery 3; or decrease due to a change in the ambient conditions. By illustrating the change in the SOiL, the uncertainty in the residual range system 1 may be reduced.

Claims

CLAIMS: 1. A system for a motor vehicle comprising an electric drive motor and an energy storage device, the system comprising: a processor configured to calculate a residual range rate of change (ROC) indicator and to output the residual range flOG indicator for display.
2. A system as claimed in claim 1, wherein the processor is configured to calculate the residual range ROC indicator over one or more pre-defined time intervals.
3. A system as claimed in claim 1 or claim 2, wherein the processor is configured to classify the residual range flOG indicator relative to at least one threshold.
4. A system as claimed in claim 3, wherein the processor is configured to reference a look-up table to determine said at least one threshold.
5. A system as claimed in any one of claims 1 to 4, wherein the processor is further configured to calculate a residual range indicative of a distance that the vehicle is capable of travelling based on the available energy in said energy storage device.
6. A system as claimed in any one of the preceding claims, wherein the processor is configured to calculate the residual range and/or the residual range ROC indicator based on a state of charge (SOC) of the energy storage device.
7. A system as claimed in any one of the preceding claims, wherein the processor is configured to calculate the residual range and/or the residual range flOG indicator based on one or more vehicle operating parameters, such as acceleration, deceleration, vehicle speed and electrical system status.
8. A system as claimed in any one of the preceding claims further comprising a display device, wherein the display device is configured to display the residual range flOG indicator as a graphical element.
9. A system as claimed in claim 8, wherein the display device is configured to represent variations in the residual range flOG indicator by altering one or more of the following characteristics of the graphical element: length, width, size, shape, colour, orientation and profile.
10. A system as claimed in claim 8 or claim 9, wherein said graphical element travels along a residual range scale.
11. A system as claimed in claim 10 when indirectly dependent on any one of claims 5, 6 01 7, wheiein said graphical element comprises a marker to indicate the calculated iesidual range.
12. A system as claimed in claim 11, wherein the position of the marker in relation to a remainder of the graphical element is indicative of an increase or a decrease in the residual range.
13. A method of indicating a residual range of a motor vehicle having an electric drive motor and an energy storage device, the method comprising the following steps: calculating a residual range rate of change (ROC) indicator; and outputting the calculated residual range ROC indicator to a display device.
14. A state of charge system for an energy storage device, the system comprising: a processor configured to calculate a state of charge (SOC) of the energy storage device and a rate of change (ROC) of the Sac; and a display device for displaying said calculated ROC.
15. A method of indicating a state of charge of an energy storage device, the method comprising the following stops: calculating a state of charge (SOC) of said energy storage device; calculating a rate of change (ROC) of the SOC of said energy storage device; and outputting the calculated ROC to a display.
16. A vehicle comprising a residual range system as claimed in any one of claims 1 to 12; or a state of charge system as claimed in claim 14.
17. An apparatus, a systeni, a method or a vehicle constructed and/or arranged substantially as described herein with reference to one or more of the accompanying drawings.