Electric Motor Vehicle
CROSS REFERENCE TO RELATED APPLICATIONS
This application claims priority from United Kingdom Patent Application No. 10 14 173.7, filed 25 August 2010, United Kingdom Patent Application No. 10 14 582.9, filed 02 September 2010, United Kingdom Patent Application No. 10 14 884.9, filed 08 September 2010 and United Kingdom Patent Application No. 10 14 970.6, filed 09 September 2010, the whole contents of which are incorporated herein by reference in their entirety.
BACKGROUND OF THE INVENTION 1. Field of the Invention
The present invention relates to an electric motor vehicle having a chassis for supporting operational components. A method of controlling the motor vehicle and a further method of reducing the speed of the electric motor vehicle through a braking process are also disclosed. The invention further relates to a battery module of the type comprising a first plurality of substantially planar electric cells, each supported within a substantially flexible wrapper.
2. Description of the Related Art
Electric motor vehicles have become more attractive in recent times, partially due to a desire by many consumers to drive more environmentally friendly vehicles which reduce pollution to the atmosphere by creating fewer harmful emissions. Most currently available electric vehicles are designed primarily for this purpose, while concentrating less on performance and often using heavy and bulky blocks of batteries, such as lead-acid batteries. Thus, problems exist in terms of designing electric powered vehicles that meet the performance of conventional hydrocarbon fuelled vehicle designs, while
making use of available battery technology.
Battery modules are known that include planar electric cells supported within a substantially flexible wrapper, often referred to as pouch cells. Many battery technologies are configured in this way and it is likely that new chemistries will be developed and cells of this configuration will improve in terms of their storage capacity, cycle times and longevity. The present invention is not limited to a particular battery chemistry.
In many applications, it is desirable to produce battery modules with a predefined geometry. Thus, it would generally be unacceptable in many applications for the size and shape of battery modules to vary considerably from item to item. Furthermore, it is also known that it is desirable to constrain the pouch cells and for some battery chemistries it is also necessary to apply pressure to the pouch cells in order to maintain optimum battery performance and an even heat distribution. Consequently, further problems arise in terms of removing heat from the cells, which may be generated during a charging operation or discharging operation. Problems of this type also become more acute if it is anticipated that the power demand during discharge will be significant and/or under conditions where rapid charging is considered desirable.
Conventional motor vehicles using petroleum-based products as a fuel are presented with an infrastructure of filling stations in most countries such that the amount of fuel that may be carried initially does not place any constraints upon the total range of any particular journey. Even with vehicles having modestly sized fuel tanks, it is likely that for any particular journey, a driver will pass several filling stops before the vehicle actually runs out of fuel. Furthermore, in modern vehicles indicators are provided showing the amount of fuel remaining and in some vehicles this may even extend to an indication of range before further fuel is required.
It is also known that in many modern vehicles fitted with satellite navigation systems, it would be possible for a driver to compare the distance remaining to the end of the journey (with reference to the satellite navigation
system) with the range available, from the fuel indicator system. A driver is therefore often aware as to whether it is necessary to stop at a filling station and the driver may also safely assume that a filling station will be available. Satellite navigation systems are also known which provide an indication of filling stations within the area once the remaining level of fuel reaches a predetermined level.
Traditionally, electric vehicles are used to perform routine operations usually within a confined geographical area. In many situations, recharging is provided from a single facility, at the driver's base or at the driver's home and the vehicle may be recharged routinely overnight. Thus, for applications of this type, working within a warehouse or making modest journeys within city boundaries, the overall distance and energy requirements of the vehicle remain relatively constant and problems in terms of range generally do not exist.
A problem does exist in terms of using electric vehicles to perform many of the functions taken for granted in the hydrocarbon environment, such as travelling significant distances and possibly requiring additional energy before turning back to base. Presently, recharging stations are limited therefore were electric vehicles to be used for substantial journeys, there is a significant risk that the vehicle could exhaust its battery supply and thereby effectively become stranded.
It has been known for some time that it is possible to effect braking of an electric vehicle by effectively reversing the functionality of the electric motor such that instead of drawing electrical power and driving the wheels of the vehicle, it is possible for mechanical energy received from the wheels to drive the motor (which then becomes a generator) which in turn may be used to re- energise the battery. Thus, such an approach reduces wear because the braking process is not relying upon friction. Furthermore, power is returned to the battery thereby prolonging range and improving power consumption.
This process of regeneration is often seen as highly desirable but in practice it can be difficult to implement. In theory, it would be possible to
construct an electric vehicle that relies exclusively upon regenerative braking, except possibly for the provision of a parking brake. Thus, all braking would be achieved by regenerative methods while the vehicle was in motion. Two problems exist with this exclusive approach in that a reluctance exists in terms of relying upon systems of this type, although this may change over a period of time. Furthermore, it is difficult to introduce failsafe procedures for regenerative braking therefore, currently, this application is limited.
BRIEF SUMMARY OF THE INVENTION
According to an aspect of the present invention, there is provided an electric motor vehicle having a chassis for supporting operational components of the motor vehicle and a vehicle body-shell defining an overall appearance of the motor vehicle, wherein: said chassis defines a housing for rechargeable batteries, such that a substantial proportion of the strength and/or stiffness of said chassis is provided by said rechargeable batteries.
According to a second aspect of the present invention, there is provided an electric motor vehicle having a chassis for supporting operational components of the motor vehicle and a vehicle body-shell defining an overall appearance of the motor vehicle, wherein: said chassis comprises a substantially H-shaped box, having a central longitudinal section, a forward transverse section and a rear transverse section; and a plurality of rechargeable batteries are housed within said substantially H-shaped box.
According to a third aspect of the present invention, there is provided a method of assembling a motor vehicle, comprising the steps of: constructing a substantially H-shaped chassis defining a central longitudinal section, a forward transverse section and a rear transverse section; wherein the beam strength of said substantially H-shaped box is enhanced by the inclusion of a plurality of re-chargeable battery modules.
According to a fourth aspect of the present invention, there is provided a battery module, comprising: a first plurality of substantially planar electric cells, each supported within a substantially flexible wrapper; an outer support cradle
arranged to hold said planar electric cells in a substantially stacked arrangement; a second plurality of substantially planar shims, wherein each of said shims is located between a selected adjacent pair of said planar electric cells; wherein said second plurality of substantially planar shims are selected so as to define a regular geometry for the battery module, and said second plurality of substantially planar shims are arranged to transfer heat from said substantially planar electric cells during the charging and/or discharging of said substantially planar electric cells.
According to a fifth aspect of the present invention, there is provided a method of constructing a battery module, comprising the steps of: locating an outer support cradle in a jig so as to receive a first plurality of substantially planar electric cells in a substantially stacked arrangement; positioning a second plurality of substantially planar shims into said stacked arrangement so as to define a regular geometry for the battery module; and configuring said second plurality of shims to transfer heat from said substantially planar electric cells during the charging and/or discharging of said planar electric cells.
According to a sixth aspect of the present invention, there is provided a method of controlling the operation of an electric motor vehicle, comprising the steps of: receiving location data indicating the present location of the vehicle; receiving command data identifying a proposed destination for the vehicle; calculating the energy requirement for the vehicle to be driven from said present location to the proposed destination; modifying the operation of the vehicle if batteries contained within the vehicle cannot provide sufficient energy to satisfy said energy requirement; calculating a revised energy requirement based on the modifications made; and disabling the operation of the vehicle if insufficient energy is available to satisfy revised energy requirement.
According to a seventh aspect of the present invention, there is provided, in an electric vehicle, a processing device configured to control the operation of the electric vehicle, comprising: a first receiving device for receiving location data indicating the present location of the vehicle; a second receiving device for receiving command data identifying a proposed
destination for the vehicle; wherein said processing device calculates the energy requirement for the vehicle to be driven from said present location to the proposed destination and modifies the operation of the vehicle if batteries contained within the vehicle cannot provide sufficient energy to satisfy said energy requirement; and said processing device is further configured to disable the operation of the vehicle on the basis that insufficient energy is available.
According to an eighth aspect of the present invention, there is provided a method of reducing the speed of an electric motor vehicle through a braking process, comprising the steps of: receiving an indication to apply braking to the vehicle; identifying a braking condition as being in accordance with a first mode of braking or in accordance with a second mode of braking; applying regenerative braking only upon identifying said first mode of braking; and applying mechanical braking in addition to or instead of said regenerative braking upon identifying said second mode of braking.
According to a ninth aspect of the present invention, there is provided an apparatus for reducing the speed of an electric motor vehicle through a braking process, comprising: a processing device configured to receive an indication to apply braking to the vehicle and identify a braking condition as being in accordance with a first mode of braking or in accordance with a second mode of braking; wherein said processing device applies regenerative braking only upon identifying said first mode of braking and applies mechanical braking in addition to or instead of said regenerative braking upon identifying said second mode of braking. BRIEF DESCRIPTION OF THE DRAWINGS
Figure 1 shows an example of an electric motor vehicle;
Figure 2 shows a schematic plan view of the electric vehicle of Figure 1;
Figure 3 shows a schematic structure of the H-frame chassis of Figure
Figure 4 shows a schematic cross-sectional front view of a body-shell;
Figure 5 shows a schematic plan view of an alternative embodiment of the present invention;
Figure 6 shows a schematic plan view of a further alternative embodiment of the present invention;
Figure 7 shows an alternative embodiment of the present invention in schematic plan view;
Figure 8 shows an example of a battery module for an electric motor vehicle of the type described herein;
Figure 9 shows a plurality of pouch cells as received from a supplier;
Figure 10 shows a pouch cell removed from its packaging for installation within a battery module;
Figure 11 shows a planar shim of substantially regular configuration;
Figure 12 shows a regular fat shimming sink plate;
Figure 13 shows a wedge-shaped shimming sink plate;
Figure 14 shows an alternative configuration for a shimming sink plate;
Figure 15 shows an outer support cradle configured to apply lateral pressure to the substantially stacked arrangement of planar electric cells and shims;
Figure 16 shows the method for constructing a battery module;
Figure 17 shows a complete stack of planar electric cells in combination with planar shims;
Figure 18 shows the complete stack of Figure 17 following closure of the cradle of Figure 15;
Figure 19 shows the top of the battery module of Figure 15 having a cover applied thereto;
Figure 20 shows a complete battery module;
Figure 21 shows an embodiment of the present invention directed towards controlling the operation of an electric motor vehicle;
Figure 22 shows communication with the vehicle via mobile telephony; Figure 23 shows an example of a processing system for a vehicle;
Figure 24 shows procedures performed by the processor shown in
Figure 25 shows an example of procedures for modifying the operation of the vehicle;
Figure 26 shows a table populated by procedures invoked for looking at alternative routes;
Figure 27 shows a table populated by the process of Figure 25 concerning equipment savings;
Figure 28 shows a first table considering speed reduction and a second table considering acceleration reduction;
Figure 29 shows a system for reducing the speed of an electric motor vehicle through a braking process;
Figure 30 shows the electric vehicle provided with a foot operated accelerator and a foot operated braking pedal;
Figure 31 shows an example of regenerative braking; and
Figure 32 shows diagrammatic representations of the percentage travel of a braking command.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
An example of an electric motor vehicle is shown in Figure 1. The electric motor vehicle 101 comprises a vehicle body-shell 102 and a chassis for supporting operational components of the motor vehicle, detailed in Figure 2. The chassis comprises a substantially H-shaped box which is shown further in the schematic plan view of the electric motor vehicle shown in Figure 2.
A schematic plan view of electric motor vehicle 101 is illustrated in Figure 2. The internals of the electric motor vehicle include the chassis 201 , electric motor 202 and electric motor 203.
Chassis 201 comprises a substantially H-shaped box and, in an
embodiment, is manufactured as an aluminium sandwich structure with an aluminium honeycomb core. It is to be appreciated that different composite structures could be used in alternative embodiments. Chassis 201 further has a central longitudinal section 204, a forward transverse section 205 and a rear transverse section 206 and the H-shaped box is configured to house a plurality of rechargeable batteries, such as those described with respect to Figure 8.
Electric motor vehicle 101 also has a front axle 207 and a rear axle 208. Front axle 207 is supported in front of forward transverse section 205 and similarly, rear axle 208 is supported behind rear transverse section 206. Furthermore, in front of forward transverse section 205 there is provided an engine compartment 209 which is configured to hold electric motor 202. Similarly, a second engine compartment 210 is present behind rear transverse section 206 which is configured to hold electric motor 203.
In an alternative embodiment, electric motor 202 may not be required, and thus, engine compartment 209 can be alternatively configured to house battery modules such as the battery module shown in Figure 8. This has the added benefit of keeping the centre of gravity of the vehicle low.
At the rear of the vehicle, there is a cage 211 which is configured to house motor 203 and to support the suspension wishbones for electric motor vehicle 101.
The electric motors (such as electric motor 202 and electric motor 203) are twin AC electric motors which are produced for high power electric vehicles and, in an embodiment, are two separate AC synchronous induction motors that in turn drive reduction gearboxes. The reduction gearboxes and synchronous induction motors are housed together. In an embodiment, the speed of the motors is capable of reaching 12,000 rpm, with the gearing reducing the speed of the wheel to a maximum of 1654 rpm. This reduction allows for a geared maximum speed of up to 200 miles per hour. However, in most practical applications, this maximum speed will be reduced, possibly under electronic control.
Electric motor 203 is positioned between a left axle 212 and right axle
213 of rear axle 208. There is no direct connection between axle 212 and axle 213 but a differential effect is successfully achieved due to an increased load on the inside wheel of the vehicle giving rise to an automatic limited slip differential. Additional electronics are not required but torque vectoring may be used in order to specify the degree of torque required for each motor.
Figure 3 shows a schematic side view structure of H-frame chassis 201 in isolation from the body-shell 102 of electric motor vehicle 101. The aluminium composite chassis 201 provides beam stiffness and space in which to house the battery modules. Thus, chassis 201 provides beam strength in order to withstand the bending forces indicated by arrow 301 and arrow 302.
Chassis 201 is connected to body-shell 201. The body-shell lacks beam stiffness but has substantial torsional rigidity. The combination therefore provides a strong engineering solution.
The substantially H-shaped box of chassis 201 introduces minimal additional weight beyond that provided by the housed battery modules such that a substantial proportion of the beam stiffness provided by the substantially H-shaped box of chassis 201 is provided by the battery modules. In an embodiment, dimensions of the battery modules and that of their containing box defined by the H-shaped chassis are such as to provide a substantially tight fit between the battery modules and their constraining box. Furthermore, in an embodiment, the batteries are constrained at their top and bottom surfaces, such that when so constrained, they enhance the overall stiffness and strength of the chassis. In some applications, this may allow the walls of the chassis to be made thinner with fewer cross braces, without risking instability to the beam-providing function of the chassis; it being appreciated that long and supported links have a tendency to become unstable and may ultimately flex. In an embodiment, the batteries are solely contained within the H-frame; however, in alternative embodiments it may be desirable to place additional battery modules outside the H-shaped box section.
In this embodiment, however, by having the batteries housed within the H-frame, performance is enhanced by mass centralisation; that is, the main weight of the vehicle is situated between front axle 207 and rear axle 208, thereby giving the vehicle enhanced inherent handling. This type of mass centralisation improves the performance of the vehicle; even when compared to a conventional mid-engined vehicle in which the engine is not actually at the centre of the vehicle, but positioned just in front of the rear wheels.
A schematic cross sectional front view of body-shell 102 is shown in Figure 4. As described in Figure 3, body-shell 102 has substantial torsional stiffness and when combined with the beam strength of the H-shaped chassis provides for a dynamically balanced vehicle.
Front axle 207 and rear axle 208, as illustrated in Figure 2, cause body- shell 102 to twist in the direction of arrow 401 and arrow 402, indicating the torsional forces the overall structure is subjected to.
With respect to the manufacture of the motor vehicle, the provision of a separate chassis and a separate body-shell allows for a method of manufacture that facilitates assembly and repair. Body-shell 102 can be lifted from chassis 201 providing access to the power-train for ease of maintenance.
The stiffest points of a motor vehicle are usually behind the front door and in front of the rear wheels. Therefore, in an embodiment, it is suitable to make use of these points for attachment of the chassis 201 to the body-shell 102.
In an alternative embodiment, body-shell 102 may be manufactured with greater strength than required for the complete structure, as this would aid transport of the body-shell when it is separated from the chassis. However, when the chassis and body-shell are combined, body-shell 201 does not require beam stiffness and this allows for weight reduction of the body-shell to improve overall performance of the vehicle.
Figure 5 shows a schematic plan view of an alternative embodiment of the present invention. Chassis 501 comprises a substantially H-shaped box, having a longitudinal central section 502, a forward transverse section 503 and a rear transverse section 504. Forward transverse section 503 and rear transverse section 504 are substantially similar to forward transverse section 205 and rear transverse section 206 depicted in Figure 2. However, in this embodiment, the H-shaped box is configured such that the number of battery modules contained within longitudinal central section 502 is variable, so as to vary the length of the vehicle. This allows for flexibility in terms of the wheel- base and overall length of the vehicle.
Figure 6 shows a schematic plan view of a further alternative embodiment of the present invention. Chassis 601 comprises a substantially H-shaped box, having a longitudinal central section 602, a forward transverse section 603 and a rear transverse section 604.
Longitudinal central section 602 is substantially similar to longitudinal central section 204 depicted in Figure 2. However, in this embodiment, the H- shaped box is configured such that the number of battery modules contained within forward transverse section 603 and rear transverse section 604 are variable so as to vary the width of the vehicle.
Figure 7 shows an alternative embodiment of the present invention in schematic plan view indicating the result of varying both the width and the length of the motor vehicle. Chassis 701 comprises a substantially H-shaped box, having a longitudinal central section 702, a forward transverse section 703 and a rear transverse section 704.
In this particular embodiment, longitudinal central section 702 is substantially similar to longitudinal central section 502 of Figure 5, showing an
increase in the overall length of the vehicle. Furthermore, forward transverse section 703 and rear transverse section 704 are substantially similar to forward transverse section 603 and rear transverse section 604 of Figure 6, allowing for an increase in the overall width of the vehicle.
The modifications shown in Figure 7 allow for a greater number of battery modules to be included in the motor vehicle and allow for variations in a motor vehicle manufacturers' vehicle portfolio.
It is appreciated that alternative combinations of battery modules can be contained within the sections of the H-shaped box, other than those illustrated by example here, such that any suitable number of battery modules may be used to give a desirable width and/or length of a vehicle.
An example of a battery module for an electric motor vehicle of the type described herein is shown in Figure 8.
In this embodiment, the H-shaped box of chassis 201 houses a plurality of battery modules, such as battery module 801. Battery modules such as battery module 801 may be of the type disclosed further in Figures 9 to 21. However, it is appreciated that other suitable battery modules can be used in this application.
Battery module 801 includes a plurality of substantially planar rechargeable electric cells such as electric cell 802. In this embodiment, each individual module comprises 16 cells, although any suitable number of cells may be used.
The lower floor 803 of the H-shaped box of chassis 201 may further include conduits, such as conduit 804 and conduit 805 for the transmission of cooling fluid.
As discussed in relation to the battery module itself below, a cold plate may be built into the floor of the chassis. In addition to conduits 804 and 805, the bottom section 806 of the chassis may comprise a single cold plate or a series of cold plates built into the section. This is discussed in further detail in
The plurality of battery modules contained within the H-shaped box of chassis 201 and their mass also provides damping for the suspension of the electric motor vehicle 101. In a motor vehicle, it is desirable to absorb vibrations, in particular those of second order frequencies, and the weight of the batteries can be arranged such that the batteries provide an effective damper for the overall structure thereby improving ride and handling.
A plurality of pouch cells, including pouch cell 901 are received from a supplier constrained within substantial packaging, including box 902 in order to ensure that no damage occurs during transit. As is known in the art, the pouch cells are very efficient to make and very efficient to use, compared to conventional cylindrical cells. The pouch cells are efficient to use given that redundant packaging is substantially reduced allowing the operational components of the cell to be closely packed within a battery module. However, it is appreciated that the pouch cells must be handled with care during their transportation and installation within battery modules.
Pouch cell 901 is removed carefully from its packaging 902 for installation within a battery module, as described with reference to Figures 19 through 20. The individual cells include a positive terminal 1001 and a negative terminal 1002 and as an individual cell, the potential difference seen across terminals 1001 and 1002 is relatively modest (typically between 1.5V and 2.5V depending on battery chemistry) but for a single cell the amount of current that may be drawn is substantial and the internal resistance of the cell is relatively low. Thus, it is possible to obtain substantial amounts of power from a battery constructed from a plurality of cells of this type electrically connected together.
It is known for pouch cells, such as pouch cell 901 , to be compressed together when placed in a battery configuration and the degree to which pressure is required when so compressed will depend upon battery chemistry. However, when compressed together in a stack to form a battery configuration, the individual pouch cells compress differently such that were they to be removed from this configuration, it becomes clear that they have adopted different shapes. Such an attribute of pouch cells is undesirable in that when a plurality of the cells are brought together the resulting geometry becomes unpredictable and a sequence of batteries produced in this way will not present the same shape and size when considered at tolerances normally expected within many engineering environments.
The present embodiment provides for the inclusion of planar shims wherein each of these shims is located between a selected adjacent pair of planar electric cells. An example of a shim 1101 is shown in Figure 11 and, in the example shown in Figure 11, the shim 1101 has a substantially regular configuration.
The shim 1101 includes a first planar face 1102 and a second planar face 1103, obscured in the drawing. Planar face 1102 and planar face 1103 are configured to contact respective pouch cells, as described with reference to Figure 16.
The shim 1101 has a first side edge 104 and a second side edge 1105. The shim also has a top edge 1106 and a bottom edge 1107. The planar faces 1102 and 1103 are forced into contact on either side with shimming sink plates or pouch cells of the type substantially similar to pouch cell 901. Thus, the first role of the shims is to act as a shim so as to define a regular geometry for the battery module. In addition, the shims act as sink plates in that they are also arranged to transfer heat from the substantially planar electric cells during the charging and/or discharging of these planar cells. Thus, in operation, heat is transferred to one or more of edges 1104 to 1 07. In an embodiment, one of these edges may include a wider surface area
so as to place a larger surface area in contact with a cold plate and thereby enhance the transfer of heat energy. In an application for an electric vehicle, an embodiment provides a wider surface area at the bottom edge 1107 and this wider surface area may be brought into contact with a cold plate running along the floor of the vehicle. (This arrangement is also utilised in an application for a static power system.) To enhance thermal conductivity, the sink plates may be constructed from copper or a thermally conductive epoxy material.
The sink plate (shim) shown in Figure 11 may be considered as a relatively thin regular plate.
A regular fat shimming sink plate 1201 is shown in Figure 12. The shimming sink plate of Figure 12 would be selected when a larger gap is to be filled but still of a regular geometry. Thus, the fat sink plate of Figure 12 includes a first planar surface 1202, a second planar surface 1203, a first side edge 1104, a second side edge 1205, a top edge 1206 and a bottom edge 1207.
A wedge-shaped shimming sink plate 1301 is shown in Figure 5. This has a first planar surface 1302, a second planar surface 503, a first side edge 1304, a second side edge 1305, a top edge 1306 and a bottom edge 1307. In this example, bottom edge 1307 is substantially wider than top edge 1306. Side edges 1304 and 1305 taper from the wide dimension at the bottom to the smaller dimension at the top. This sink plate 1301 provides for situations where the assembly of pouch batteries presents a wider gap at one side compared to the other side. In an embodiment where all of the edges 1304 to 1307 are substantially similar with respect to their heat transfer characteristics, it can be seen that the sink plate of Figure 13 may be used in any of its four orientations. However, if one of the edges, such as bottom edge 1307, is to
provide enhanced thermal conductive properties, it can be seen that three shimming sink plates with this configuration would be required, with a modified edge being at a bottom 1307, a top 306 or at an edge, such as edge 1304.
An alternative configuration for a shimming sink plate 1401 is shown in Figure 14. Again, the sink plate has a first planar face 1402, a second planar face 1403, a first side edge 1404, a second side edge 1405, a top edge 1406 and a bottom edge 1407.
In this example, the shimming sink plate tapers from a wide comer 1408 to a narrow corner 1409, with corners 1410 and 1411 being of an intermediate dimension.
If one of the edges is to be modified to enhance heat transmission, four separate shim plates of the configuration of Figure 14 would be required, given that the configuration lacks the geometry of the wedge-shaped shimming sink plate of Figure 14.
Experiment has shown that the four configurations of shimming sink plate, shown in Figures 11 through to 14 allow any collection of pouch cells to be assembled so as to form a battery module with a regular geometry.
As illustrated in detail in Figures 1 to 8 an electric vehicle is described that has a large honeycomb box for restraining the battery packs that will to some extent remove the heat generated by these battery packs. In the disclosed embodiment, the bottom part of the box is within the air flow underneath the vehicle such that some of the heat will be removed by the chassis. However, it is anticipated that for high performance applications, additional cooling strategies may be required.
An option would have been to take advantage of natural heat conduction under which the heat would tend to rise from the collection of battery modules. However, were a liquid cooling system to be placed above
the battery packs, significant damage could occur to the batteries and associated electronics should a cooling system failure occur. Thus, to avoid problems of this type, an embodiment is configured to direct the heat downwards to a cooling plate located at the bottom surface of the vehicle. Thus, in this application, the provision of the substantially planar shims (sink plates) provides a mechanism for removing heat from the bottom surface of the battery modules by the provision of a series of cold plates built into the floor of the chassis of the vehicle that include cooling coils that cool the plates upon which the batteries sit. Thus, in operation, the heat exits from the battery pack through the sink plates, through cold plates forming part of the vehicle and then towards cooled water pipes beneath the cold plates that are in turn connected to a radiator system. If the coolant fails, the coolant cannot fall into the battery connections and will drain out through drains provided in the bottom of the battery container.
In an embodiment, it is considered desirable for the pouch cells to be restrained mechanically so as to prevent individual cell vibration which could in turn lead to mechanical damage. Furthermore, it is understood that for some cell technologies, it is necessary to place the cells under pressure. The optimum level of pressure required would usually be specified by the manufacturer of the pouch cell. An example technology requires 526 kg of force to be applied for optimum performance.
In an embodiment, an outer support cradle 1501 is configured to apply lateral pressure to the substantially stacked arrangement of planar electric cells and shims.
In an embodiment, the outer support cradle is substantially U-shaped with a substantially horizontal base portion 1502, a first substantially vertical side portion 1503 and a second substantially vertical side portion 1504.
In an embodiment, the cradle 1501 is assembled from a first substantially L-shaped member and a second substantially L-shaped member which may be of substantially similar configuration. The two L-shaped members are supported within a jig, defining the required dimension between
vertical edges 1503 and 1504 and joined together (for example by welding) so as to define the overall U-shaped cradle. In this way, the dimensions of the cradle may be finalised during the assembly process.
As shown in Figure 15, the first substantially vertical side portion 1503 and the second substantially vertical side portion 1504 are configured to flex outwards so as to allow the introduction of the electric cells 901 and the shimming sink plates 103.
At the locations where the vertical side portions 1503, 1504 meet the base portion 1502, it is preferable for a radius 1505 and 1506 respectively to be provided so as to facilitate the hinging action as shown in Figure 15. Furthermore, having located the electric cells and the shimming sink plates within the cradle 1501 , a first mechanical ram 1507 and a second mechanical ram 1508 are arranged to compress the vertical side portions (1503, 504) together thereby creating the requisite geometry and also ensuring that an appropriate degree of force has been applied thereby compressing the battery packs together. In the present embodiment the mechanical rams 1507 and 1508 are hydraulic rams.
Figure 16 illustrates the method for constructing a battery module that embodies an aspect of the present invention. The outer support cradle 1501 is located in a jig 1601 so as to receive a first plurality of substantially planar electric cells 901 in a substantially stacked arrangement. In this embodiment, four electric cells 1602 have been arranged in the cradle 1501 in a stacked arrangement. A second plurality of substantially planar shims (the shimming sink plates) are positioned into the stacked arrangement so as to define a regular geometry for the battery module. In the example shown in Figure 16 a single shimming sink plate 1603 has been included in the stack. As previously described, once configured the second plurality of shims transfer heat from the substantially planar electric cells during the charging and/or discharging of these cells. In an embodiment, this transfer of heat will take place vertically
downwards in the direction of arrow 1604.
In an embodiment, the base portion 1502 is formed of straps of material that define openings in the base portion though which the shimming sink plates are able to extend. Thus, in this embodiment, the sink plates contact the cold plate directly, thereby avoiding loss of conductivity as a result of attenuation through the base portion. In addition, a thermally conductive and flexible material may be loaded between the sink plate and the cold plate. Furthermore, the assembly may include a means of ensuring that the bottom faces of the sink plates are held in good thermal contact with the cold plate underneath.
In the present embodiment, the cells are stacked in groups of four between shimming sink plates, but in alternative embodiments other numbers of cells are stacked together between shimming sink plates. For example, in one embodiment only a single cell is located between a pair of sink plates, while in another embodiment a pair of cells are located side by side between a pair of sink plates.
The reception of planar electric cells in combination with the positioning of the planar shims continues until a complete stack 1701 has been defined, as illustrated in Figure 17. This includes the first group of four electric cells 1602, along with a second group 1702, a third group 1703 and a fourth group 1704.
In other examples, more, or less, groups and shimming sink plates than shown in Figure 17 may be combined in a stack as defined by specific design requirements.
Shimming sink plate 1603 is now located between group 1602 and group 1602. Similarly, a shimming sink plate 1705 is located between cell group 1702 and cell group 1703. Finally, shimming sink plate 1706 is located between cell group 1703 and cell group 1704.
During the construction process, appropriate shimming sink plates are
selected from the types illustrated in Figures 11 through 14. In this way, the regular geometry of the stack 1701 as a whole is ensured.
Having established stack 1701 , the cradle 1501 is closed by the application of force applied via mechanical ram 1507 and mechanical ram 1508. In this way, lateral pressure is applied to the stacked arrangement 1701 of planar electric cells and shims which is then held in place by an upper securing portion. Furthermore, in an embodiment, the upper securing portion includes a cavity for retaining control and monitoring circuitry. Thus, after the required degree of pressure has been applied by mechanical rams 1507 and 1508, an upper securing portion is located so as to secure the first vertical side portion 1503 and the second vertical side portion 1504 permanently in the configuration as illustrated in Figure 18.
In an embodiment, bottom edge 1801 of shim 1603, bottom edge 1802 of shim 1705 and bottom edge 1803 of shim 1706 are arranged to co-operate with a heat transfer surface after the battery module has been installed. In an embodiment, bottom edges 1801 , 1802 and 1803 may define an inverted T profile so as to enhance the heat transfer properties of these edges.
It should be appreciated that the exact number of electric cells contained within the battery module is variable and will depend upon application. In an embodiment, the battery module is designed so as to provide a substantial and significant amount of electrical power while at the same time being of a size and weight to facilitate installation by a single operative. Similarly, the size of the cell groupings and the quantities within the cell groupings, 1602, 1702, etc. is variable and may be determined by the degree of heat transfer required for a particular application. In an embodiment, there are between two and six planar electric cells located between each of the shims. In the example shown in Figures 17 and 18, four electric cells are provided within each group and there are a total of sixteen cells within the module, requiring a total of three shimming sink plates. Again, this
configuration should not be seen as preferred, as its advantages would depend upon the particular application required.
In an embodiment, the number of cells within a module is constrained such that the series connected total voltage of all cells is less than a predetermined voltage to minimise the potential danger to the module builder and user in terms of electric shock and manual handling weight.
The top of the battery module of 1501 is shown in Figure 19, having an upper securing portion or cover 1901 applied thereto. The enclosing cover is made slightly too small so as to prevent an interference fit. It is stretched open to allow the cells to be positioned and then clamped together. Thus, while the mechanical rams 1507 and 1508 are in the position shown in Figure 18, the cover 1901 is applied, thereby restraining vertical portion 1503 and vertical portion 1504, in turn allowing the mechanical rams to be removed, in anticipation of the next battery module being assembled. The cover 1901 includes a cavity 1902 for retaining local control and monitoring circuitry 1903. In this embodiment, the individual electric cells are collected in series within the battery module such that the battery presents a positive terminal 1904 and a negative terminal 1905. The series connections within the battery are not shown in Figure 19 and it should be appreciated that other configurations are possible, such as providing groups of individual cells being connected in parallel etc. The positive terminal 1904 and the negative terminal 1905 are connected to the control circuitry 1903. The control circuitry 1903 in turn provides a positive connection 1906 and a negative connection 1907 upon the outside of the cover, thereby providing connectivity to components external to the battery module.
In this embodiment, heat sensitive devices, such as a first thermistor 1908 and a second thermistor 1909 are placed in contact with shimming sink plate 1603 and shimming sink plate 1706 respectively. In this way, it is possible for the local control circuitry 1903 to monitor the electromotive force
produced by the battery, the current supplied by the battery and the operating temperature of the battery.
In an embodiment, the control and monitoring circuit 1903 is also configured to disconnect the exposed terminals 1906 and 1907 from the battery module, thereby effectively isolating any charge stored within the battery from external contact. The battery therefore remains in this condition during an assembly process and is then activated upon receiving a commissioning signal from a central controller.
In the present embodiment, the cover 1901 is secured in place by a clipping mechanism illustrated in the enlarged view at 1950. The clipping mechanism comprises an outwardly extending bulge 1951 in the vertical portion 1503 towards its upper edge and a correspondingly shaped groove 1952 formed on the inside surface of the rim 1953 of the cover 1 101.
A complete battery module 2001 is illustrated in Figure 20. The upper securing portion 1901 covers the upper edges of the planar electric cells thereby fully protecting these cells. The cover 1901 also prevents access to the individual terminals of the cells held within the battery 2001. Once commissioned, external terminals 1906 and 1907 facilitate the provision of electrical power to the operational device. In an embodiment, a plurality of cells of the type shown in Figure 20 are connected together so as to provide electrical power to a motor vehicle. In another embodiment, a plurality of cells of the type shown in Figure 20 are connected together so as to provide electrical power to a static power system. Figure 21
An embodiment of the present invention, shown in Figure 21, is directed towards controlling the operation of an electric motor vehicle 2101 , in which location data is received identifying the present location of the vehicle. As detailed in Figure 23, a processor may receive location data via a global
positioning satellite system or similar external infrastructure for providing a geographical location.
Vehicle 2101 receives command data identifying a proposed destination for the vehicle. As shown in Figure 21, this command data may be received in conventional fashion by manually interfacing with a touch screen 2102 of what may appear as a substantially conventional satellite navigation system. Thus, in the embodiment, the system is presented with an indication of the current location and an indication of a proposed destination, from which it is possible to calculate a route using known satellite navigation heuristics.
Where the embodiment of Figure 21 differs from that of conventional satellite navigation systems is in that the system calculates the energy requirement for the vehicle to be driven from the present location to the proposed destination. It will then modify the operation of the vehicle if batteries contained within the vehicle cannot provide sufficient energy to satisfy the energy requirement.
An embodiment of the present invention is directed towards a high performance electric vehicle with sophisticated data processing capabilities (detailed in Figure 23) contained on board. It is therefore possible for this data processing facility to extend the capabilities of the vehicle and to enhance the overall driver experience. In the example of Figure 22, communication with the vehicle 2101 is made possible via mobile telephony, using a conventional mobile cellular telephone 2201. In the embodiment, the vehicle (or more correctly the processing capability within the vehicle) recognises the source of the voice and is thus able to distinguish a particular driver from a set of drivers regularly using the vehicle. Furthermore, in an embodiment this approach could be extended further to the extent that the vehicle would be disabled were the voice not recognised as an authorised driver.
Upon recognising the source of the voice as that belonging to an authorised driver, the vehicle adjusts driver comfort devices (steering wheel
extent and tilt, seats, mirrors and pedals, etc.) into a position preferred by that driver.
Using mobile cellular telephone 2201 it is possible to identify destinations to the vehicle by a process of speech recognition. In an embodiment, the vehicle is preloaded with voice templates used to identify destinations for which journeys are made regularly. A voice command of this type would be compared against this stored list and in an embodiment a hand shaking operation is performed in that a verbal acknowledgement is returned back to the driver. The driver would then be in a position to confirm (verbally) as to whether the correct destination had been identified or, alternatively, to repeat the process.
In an alternative embodiment, the speech recognition system is not provided with pre-recorded templates but relies on a more sophisticated process of speech recognition allowing the destination to be compared against an index of destinations stored within the satellite navigation system. A driver could, for example, provide a postcode to the satellite navigation system without this postcode having previously been identified as a preferred destination. The satellite navigation system could then return a more detailed account of the address selected, seek confirmation as to whether this is correct and possibly record the destination for future selection in order to enhance the selection process. Thus, the speech recognition system in combination with a satellite navigation system could be configured to perform a learning process based on an assumption that a driver will tend to make multiple journeys to the same destination or on the assumption that a driver often makes journeys to a particular geographical area.
Using mobile telephony, it is not necessary for the driver to be in the vicinity of the vehicle in order for these commands to be issued. An option would be for the vehicle to remain at a charging station such that, during the charging process, it would be possible for the driver to make several enquiries as to whether a particular journey was possible. In response to these enquiries and as described with respect to Figures 24 through 28, the vehicle
may return audio information to the effect that the journey is possible in a fully functional mode and that it is currently available for use. The driver could then move to the vehicle, enter the vehicle and drive away with the satellite navigation fully functional and in the reassurance that the vehicle has sufficient energy on board in order to complete the journey. In a further enhancement to the embodiment, it would also be possible to confirm whether the journey is of a one way nature or whether it is necessary to make a return trip without undergoing a further charge.
Situations will also arise where it is determined that insufficient charge is available for the journey to be made. Under these circumstances the vehicle may return information to the effect that further charging will be required before the journey is possible. The vehicle may also return information to the effect that the journey is only possible if further stops are made for a recharging operation to be performed during the journey. Such an acknowledgement will be made only if the vehicle is aware as to where these stops may be made.
If the vehicle determines that it is not possible to make the journey without additional charging and the system is unaware as to where charging stations are located, the journey will be considered impossible and the driver will be positively deterred. In an extreme embodiment, operation of the vehicle will be totally disabled until a new destination has been identified that is considered within the capabilities of the vehicle's batteries or within the capability of the vehicle's batteries on the assumption that a recharging process takes place at a known recharging location.
In marginal situations, the vehicle will still not commit to the journey until it can be reassured that the journey is within the range of the vehicle's capabilities. Under these circumstances sophisticated modifications are made either to internal equipment as detailed in Figure 27 or to the performance of the vehicle itself, as detailed in Figure 28.
The vehicle includes a processing system, an example of which is
shown in Figure 23. A processor 2301 is configured to control the operation of the electric vehicle and is interfaced to a first receiving device 2302 for receiving location data indicating the present location of the vehicle. Thus, in an embodiment, the first receiving device may be a GPS (Global Positioning Satellite) subsystem or any subsystem providing location data indicating the current location.
A second receiving device receives command data identifying a proposed destination for the vehicle. This may take the form of a graphical interface 2102 (as described in Figure 21) or an audio interface receiving audio communications via a mobile telephony module 2303, such as a GSM module or a module capable of digital communications using any international communication standard.
The processing device 2301 calculates the energy requirement for the vehicle to be driven from the present location to the proposed destination and modifies the operation of the vehicle if batteries 2304 contained within the vehicle cannot provide sufficient energy to satisfy the energy requirement. In the embodiment, the processing device is resident within an electric high performance sports car where it may be assumed that optimum performance is required subject to sufficient energy range being within the batteries in order for the journey to terminate at the required destination without exhausting the battery supply before the destination is reached.
The processor 2301 is required to perform many functions that are similar to the operations performed by a conventional satellite navigation system. Known satellite navigation procedures perform heuristics in which weightings are given to particular sections of road, topological paths are selected as candidates and a particular route is then chosen based on the selection that provides either the shortest distance or the shortest travel time.
In the present embodiment, similar constraints are adopted but to this mix of time and distance a further parameter is included concerning the overall energy requirement. Thus, in many situations, it may be assumed that a faster route will require more energy than a direct route. However, further constraints
may be present such as steep gradients and the inclusion of many urban areas where there is a high probability that many stopping and starting operations will be required.
The processor 2301 therefore receives this geographical data from an appropriate data storage device 2305. In an embodiment, it is also possible for the processor to receive live data, identifying traffic jams and road works for example, so that these constraints may also be brought into the overall process for calculating energy demand.
As previously described, the processor makes an assessment as to whether the journey is possible and this information is brought to the attention of the driver. However, in addition to this, the processor 2301 may also modify the operation of the vehicle so as to further reduce energy demand and therefore make the commanded destination possible. The processor 2301 therefore communicates with a drive management system 2306 which in turn has control over substantially all operations within the vehicle itself. Furthermore, during servicing and maintenance, it is possible for technicians to be given access to processor 2301 via an external interface 2307.
Procedures performed by processor 2301 are detailed in Figure 24. At step 2401 location data is received from the GPS module 2302 in order to identify the current location of the vehicle.
At step 2402 command data is received identifying the proposed destination, which may be received from the graphical interface 2102, via mobile telephony module 2303 or via any other appropriate data input device.
At step 2403 the route is navigated using substantially conventional satellite navigation heuristics. These may identify several possibilities, of which one may be the fastest route, one may be the shortest route and a third may represent the most energy conserving route. In an embodiment, it may be possible for a driver to select a default, possibly the fastest route although this may be modified to the most energy conserving route if range becomes an
issue. Thus, at step 2404 a calculation is performed to determine the energy requirement.
At step 2405 a question is asked as to whether sufficient energy is available and if answered in the affirmative, the processor 2301 facilitates driving to the location at step 2407. However, if the question asked at step 2405 is answered in the negative, to the effect that sufficient energy may not be available, operation modifications are invoked at step 2406.
Thus, in practice, an identification has been made of one of three possible states. In a first state, the proposed destination is well within range and full vehicle performance may be placed at the disposal of the driver thereby facilitating the drive to the location. In a second state, a determination may be made to the effect that it is not possible to reach the destination under any foreseeable circumstances. Thus, in the second state operation of the vehicle may be prevented until an alternative destination has been selected.
In a third state, sufficient range may be available in order to reach the destination but in order to do so modifications will be required. The driver must then accept these modifications in order that the system may provide full reassurance to the effect that the destination is within range. Thus, the system is configured such that the vehicle commits to a particular journey and once committed will take all necessary measures in order to ensure that the driver arrives at the destination. If it is not possible for the vehicle to make this commitment, the journey may be prohibited or the system may convey information to the driver to the effect that the driver is now assuming full responsibility. Figure 25
An example of procedures 2406 for modifying the operation of the vehicle are illustrated in Figure 25.
Upon entering process 2406, a determination has been made to the effect that the vehicle does not have sufficient energy, under full performance operation, to reach the destination using the preferred route. At step 2501
further investigations are made to identify alternative routes. Under these procedures, the fastest route and/or the shortest route may be rejected in preference for a route that requires less energy. This may avoid gradients and/or avoid built up areas. It may not represent the quickest way of reaching the destination but it may make reaching the destination possible without requiring the batteries to be recharged.
A further consideration taken into account during process 2501 is to identify the possibility of the vehicle being recharged while mid-journey. Thus, on the assumption that electrical charging stations of the appropriate type are not abundant, it may be necessary for the vehicle to make a detour and upon reaching the recharging station, it may be necessary for the vehicle to remain at this station for a period of time while the recharging process takes place. However, again, such a detour may convert an impossible route into a possible route, assuming the driver is prepared to accept the inconvenience.
Having considered route options, a question is asked at step 2502 as to whether sufficient energy is now available. When answered in the negative, procedures will be considered at step 2503 directed towards making energy savings by disabling equipment contained within the vehicle, as detailed with reference to Figure 27.
At step 2504 a question is again asked as to whether sufficient energy is available and when answered in the negative procedures are invoked at step 505 to consider whether it is possible to make engine savings. Examples of engine savings are detailed in Figure 8 in which the overall performance of the vehicle is reduced. For a performance vehicle such as an electric sports car, restraining the full capabilities of the car is often seen as a last resort but again this may be the only option in terms of making the journey a realistic proposal.
Having considered engine saving possibilities a question is again asked at step 2506 as to whether sufficient energy is available. When answered in the negative, a demand is made of the system for additional charging to be invoked at step 2507 such that, taking all the measures identified above or a
particular selection of these measures and ensuring that the vehicle is fully charged, it may be possible for the journey to be completed.
At step 2508 a question is again asked as to whether sufficient energy is available and if answered in the affirmative, the drive is facilitated at step 2407. However, having considered all of the possibilities for saving energy, if the question asked at step 2508 is again returned in the negative, the route is disabled at step 2509 and the driver is invited to make an alternative selection.
Procedures invoked at step 2501 for looking at alternative routes results in a table 2601 being populated.
In this example, a first column 2602 identifies the nature of the route and a second column 2603 identifies the amount of energy required for that particular route.
In this example, a fast route is populated at row 2604 and an energy value is calculated and recorded in record 2605.
This process is repeated at row 2606 with an energy value 2607 being recorded for the most direct route.
In this example, the most energy efficient route is identified as the level route (lacking gradient) at row 2608 with its energy value being recorded at 2609.
The system then goes on to identify completing the route with one stop, at row 2610 with an energy value being recorded at 2611 representing the amount of energy required for the most energy intensive leg of the two legs.
A similar exercise is performed at row 2612, in which two stops are made resulting in the journey being broken into three legs. Again, an energy value is recorded at step 2613 for the leg requiring the most amount of energy.
From the energy column 2603 it is possible to identify which, if any, of the options allows the route to be completed. Thus, for the purposes of this example, it may be assumed that anything short of energy value 2611 would not allow the journey to be completed therefore the process has concluded
that it is only possible to perform the journey if there is at least one stop.
Several issues may be analysed in order to identify the most energy efficient route. Some of these constraints will remain fixed while others will be transient and will rely upon real time data. Thus, less congested roads could be selected or roads with fewer speed restrictions could be selected. Roadworks and other temporary features could be avoided because a requirement to perform many stops and starts could significantly add to the amount of energy required in order to complete the journey.
Process 2503 concerning equipment savings results in the population of a table 2701 , as shown in Figure 27.
A first column 2702 identifies the nature of the equipment and a second column 2703 identifies a percentage energy saving when the item of equipment is disabled.
At row 2704 the air conditioning system is considered and an energy saving percentage is recorded at 2705.
The air conditioning system could be a climate control system and could include heating devices for heating an incoming air stream or cooling the incoming air stream dependent upon ambient conditions. In an embodiment, the operation of an air conditioning system is reversed to provide heating by heat pump technology. However, in some embodiments, simple resistive heating systems may be advantageous if they are relatively lighter and are only required for relatively short periods of time during an initial start-up.
Further resistive heating components may be provided, such as seat heaters and mirror heaters which again could be disabled in order to make power savings.
At row 2706 the lights are considered and again a percentage saving is recorded at 2707. It is also appreciated that additional processing will be required to determine whether it is possible to drive the vehicle without lights, depending upon time of day and the intended period within the day during
which the journey time is anticipated. The provision of interior lighting may also be considered, along with the brightness control for touch screens provided within the vehicle.
At row 2708 a power amplifier for the audio system is considered and again percentage savings are recorded at 2709. In this example, the power amplifier relates to relatively high audio outputs which in many situations will not be required. Other entertainment systems may be provided such as a television receiver and systems for replaying recorded video material. A sound emitter may be included for generating simulated engine noises (possibly as a warning to pedestrians) and again the system may be disabled. In an embodiment, the sound emitting system is first of all disabled in non-built up areas, so as to remain available in areas where there is a greater likelihood of pedestrians being present. This information would be derived from the satellite navigation subsystem.
At row 2710 all audio equipment is considered and again an energy saving is recorded at 2711.
Finally, in this example, telephony is considered at 2712 and again a percentage saving is recorded at 2713.
In an embodiment, it will be possible for a driver to identify internal equipment considered necessary and that considered optional. Thus, some drivers may have expressed a preference for retaining the air conditioning system, whereas other drivers may have expressed preferences for the audio system or the telephony system.
For a performance vehicle, many drivers would consider a limitation to the vehicle's performance to be the last measure that could be tolerated as a mechanism for saving energy. However, it is appreciated that this is likely to be the most successful mechanism for converting an impossible journey into a possible journey. In this example, engine savings procedures 2505 result in the population of a first table 2801 that considers speed reduction and a
second table 2802 that considers acceleration reduction.
At row 2803 a ninety percent speed reduction is identified and an estimated percentage saving of stored energy is recorded at 2804. Thus, under this proposal, the maximum speed available would be restrained to ninety percent. Thus, for example, a vehicle having a maximum speed of 100 kph would be restricted to a maximum speed of 90 kph.
Similarly, an eighty percent speed reduction is identified at row 2805 with the resulting estimated percentage energy saving being recorded in 2806. Similarly, row 2807 identifies a seventy percent reduction and row 2808 records a sixty percent reduction. These result in savings recorded at 2809 and 2810 respectively.
In addition to restricting the maximum speed, it is also appreciated that savings may be obtained by reducing acceleration. In table 2802 a column 2811 records acceleration reduction figures and a column 2812 records percentage savings.
In this example, a row 2813 identifies an acceleration reduction to ninety percent of maximum and an estimated energy saving is recorded at 2814.
Similarly, column 2815 identifies an acceleration reduction to eighty-five percent with the energy saving being recorded at 2816. In this example, rows 2817, 2818 and 2819 identify acceleration reductions to eighty percent, seventy-five percent and seventy percent respectively of a maximum acceleration available, with the resulting energy savings being recorded at 2820, 2821 and 2822 respectively.
In an embodiment, the system is aware of the locations of recharging stations and is also aware of the maximum power output from these recharging stations. Thus, it is possible to calculate the time required in order to achieve a complete recharge or in order to achieve a sufficient recharge in order to complete the journey or complete the next leg of the journey. The system is provided with a real time clock so that a driver may be notified, possibly by SMS, to the effect that a sufficient charge has been achieved or
that the battery is fully charged. The system also takes into account if there are vacant slots available in the recharging stations, and how long it will be before available slots become available if they are not already available.
In an embodiment, the system also identifies suitable charging stops based on the proximity to refreshment facilities such that a driver may simultaneously rest and recuperate while the vehicle is charging. If a driver wishes to rest overnight, for example, a suitable hotel can be chosen in close proximity to a charging station such that the driver may return to the journey the following morning or when the battery is fully charged.
In an embodiment, while the vehicle is being driven, the driver may be presented with an updated estimated time of arrival and a notification to the effect that a recharge stop will be required or a reassurance to the effect that a recharge will not be required and that the vehicle is capable of reaching the intended destination. Thus, this information can be updated in real time such that the system will adapt should unexpected situations arise that cause the vehicle to be delayed or re-routed. The range may further be adjusted by inputs from a driver dictating how much range to keep when reaching the destination. This allows a driver to spend minimal time at an en route charging point.
In a further embodiment, a driver can input a plurality of journeys to be undertaken in a sequence. The driver can use the system to plan a number of journeys with intermediate charging stops as required such that the final journey can finish with minimal charge remaining.
In an embodiment, the system also contains information regarding outdoor temperatures and weather conditions. This information is extrapolated to calculate the effects on the air conditioning, heating and ventilation equipment, and the energy required used in determining the range available in accordance with any of the previous embodiments. The temperature is further used to calculate range dependent on the impact on battery performance and losses due to heating and cooling the batteries.
In an embodiment, a driver is also provided with choices that have
different impacts on range and operating performance. For example, a setting could be provided for a driver to input no constraints on power usage. Alternatively, the driver may wish to input a sport setting which would maximise power from the electric motors but limit the heating, air conditioning and ventilation. A further alternative setting may be provided for comfort with a reduce power setting from the electric motor but with full air conditioning, heating and ventilation. A driver may also select a maximum range setting which could operate under reduced power with, for example, a 50 mph speed limit for the vehicle and no air conditioning, heating or ventilation. Figure 29
A system for reducing the speed of an electric motor vehicle through a braking process is shown in Figure 29. A processing device 2901 receives an indication to apply braking from a brake application device 2902. Upon receiving this command to apply braking, a processor 2901 identifies the braking condition as being in accordance with a first mode of braking or in accordance with a second mode of braking. The processor 2901 provides an output signal to a regenerative braking control subsystem 2903 which will cause the vehicle to brake by the application of regenerative braking, detailed in Figure 31. The processor 2901 may also apply control signals to a hydraulic braking subsystem 2904, configured to apply a mechanical brake so as to reduce velocity or bring the vehicle to a stop in a more conventional manner.
The processor 2901 applies regenerative braking only upon identifying the first mode of braking. Upon identifying the second mode of braking, the processing device applies mechanical braking either in addition to the regenerative braking or as an alternative to the regenerative braking.
In order for the processor 2901 to make a decision as to whether the first mode of braking should be applied or the second mode of braking should be applied, an embodiment provides additional information to the processor 2901 concerning the condition of the vehicle. In the example of Figure 29, processor 2901 receives an indication of speed from a velocity measuring
device 2905 and receives an indication as to whether cruise control is being used from a cruise control indicator 2906. In an embodiment, the system also includes a fault detection subsystem 2907 associated with the regenerative braking subsystem 2903. Thus, information is provided to processor 2901 upon detection of a fault, which again may have an influence upon whether the first mode of operation or the second mode of operation is selected.
Within a vehicle operating substantially under electronic control, it is possible for many types of interface devices to be deployed in order to cause an activation of the braking system. However, in an embodiment, the electric vehicle is designed to operate in a way that is familiar to drivers of conventional hydrocarbon powered vehicles.
In an embodiment, the electric vehicle is provided with a foot operated accelerator 3001 and a foot operated braking pedal 3002. Thus, the brake application subsystem 2902 includes pedal 3002 and the subsystem 2902 is configured to determine the extent to which the pedal 3002 has been depressed, or the extent to which force has been applied to the pedal 3002.
Conventionally, the application of a brake pedal results in pressure being applied to a hydraulic system in which the pedal returns to its original condition when pressure is removed. This in turn gives the pedal a particular mechanical feel which provides feedback to the driver and ensures that the pedal is depressed by the requisite amount in order to obtain the desired level of braking. Many modern vehicles have moved away from this system and towards a "drive by wire" approach in which the pedal is effectively mechanically detached from the braking system itself and electric sensors are used to determine the extent of braking required. It is also known for braking systems to include varying degrees of servo assistance so again feedback mechanisms to the driver to achieve the required level of brake activity are somewhat artificial. In the present embodiment, pedal 3002 is therefore provided with appropriate springing mechanisms in order to give the driver a
recognisable feel but data relating to the level of pedal activity is, in the embodiment, related to processor 2901 as a digital signal. This digital signal identifies the degree of movement of the pedal or the extent to which force has been applied to the pedal.
Thus, in an embodiment, the first mode of braking is identified in response to the brake pedal 3002 being depressed by a predetermined degree (distance or force) and the second mode of braking is identified in response to the brake pedal being depressed beyond said predetermined degree. Thus, in operation, a first movement of brake pedal 3002 will result in the first braking mode being selected and the braking process being achieved exclusively by regenerative braking. However, should an emergency condition arise for example, the brake pedal 3002 is pressed further, beyond the predetermined limit, resulting in the hydraulic braking system 2904 being activated. Thus, in the embodiment, mechanical braking is used in combination with the regenerative braking.
In many systems using regenerative braking, a problem exists in that the braking may be applied automatically whenever the accelerator pedal is released. This is disconcerting for many drivers as the car starts to brake before the driver has taken action to invoke the braking systems. In an alternative embodiment, it is possible for a first proportion of the braking degree to be provided by mechanical braking so as to provide a familiar feel. Once the braking degree reaches a predetermined level, say, above ten percent, the mechanical braking is replaced by regenerative braking. Thereafter, in accordance with the present invention, mechanical braking is reintroduced should the degree of braking exceed a second threshold of, say, seventy percent. Thus, it is possible to have a sophisticated system in which the braking is initiated by mechanical braking, subsequently replaced by regenerative braking and then again reintroducing mechanical braking. Such a procedure introduces a feel to the driver in an electric performance car that is substantially similar to that experienced in high performance petrol cars.
An example of regenerative braking is illustrated in Figure 31. Under normal operation, a battery 3101 supplies electrical energy to a motor 3102. To reduce weight and improve the efficiency of motor 3102, the motor is a synchronous AC motor and as such requires an alternating current. An output from battery 3101 is supplied to an inverter 3103 which then supplies alternating current to the motor 3 02 via a switching system 3104. The flow of power to the motor 3102 is indicated by arrow 3105 and arrow 3106. Arrow 3105 and arrow 3106 do not represent current flow, however, due to the alternating nature of the current.
In response to a command for regenerative braking, switching system 3104 stops providing power to the motor 3102 and now receives power from the motor 3102, as represented by arrow 3107 and arrow 3108. The alternating regenerated current generated by motor 3102 is returned to the battery 3101 through a rectifying system 3109 such that, by the regenerative process, current flow through the motor 3102 resists mechanical rotation (thereby achieving braking) while the power generated is returned to battery 3101. However, it is appreciated that sophisticated electronics are required within rectifying circuit 3109 in order to return regenerated power to the battery 3101 in a form that allows the battery to be recharged without causing damage to the battery, as is known to those skilled in the art.
In an embodiment, the motor vehicle includes an adaptive cruise system 2906. The adaptive cruise system operates in a manner similar to a conventional cruise control, controlling the vehicle such that it maintains a selected speed. However, an adaptive cruise control system is provided with radar detectors which will identify the presence of slower moving vehicles ahead and automatically compensate so as to maintain a predetermined distance between the vehicle and the vehicle in front. In an embodiment, the first mode of braking is selected if the command for braking originates from the
cruise control. A diagrammatic representation of this approach is shown in Figure 32. An arc 3201 illustrates the travel of a braking command which, for adaptive cruise, will originate form the cruise control system and not from the application of the driver's foot. The example shows that when a call for braking is made under adaptive cruise control, one hundred percent of the braking is achieved using regenerative braking and the automatic system does not make any use of the mechanical hydraulic system.
An alternative mode of operation is illustrated at 3202. On this occasion, the vehicle is travelling at high speed and it is accepted that at high speed regenerative braking is more effective. Consequently, when travelling at high speed the first seventy percent of the demand for braking will be met by regenerative braking. Thus, brake pedal 3002 may be depressed by a full seventy percent of its travel before the mechanical braking system will be activated. Thus, the second mode of braking is only achieved after seventy percent of the call for braking has been deployed.
An alternative arrangement is shown at 3203 in which the vehicle is travelling at low speed. On this occasion, it is appreciated that regenerative braking is less effective and therefore the first mode of operation is only present for the first thirty percent of the call for braking. Thus, after foot pedal 3002 has travelled by only thirty percent of its full distance, further activation will introduce mechanical braking, with less reliance overall being made of the regenerative system.
Arc 3204 illustrates a situation which occurs when the vehicle is stationary. When the vehicle is switched off, parking brakes may be applied, possibly automatically. However, alternative braking systems are required if the vehicle stops temporarily, in traffic or in response to traffic control measures. Under these circumstances, it would be possible for the vehicle to be held stationary using the regenerative process or at least partially by activating the electric motor in reverse. However, in the embodiment this is seen as an unacceptable waste of power therefore it would be preferable for mechanical braking to be deployed. Thus, as soon as a detection is made to
the effect that the vehicle is stationary, no braking whatsoever is provided by the regenerative system and one hundred percent of braking is provided by the mechanical system. Thus, when the vehicle is stationary, a slight activation of foot brake 3002 will cause the mechanical braking system to be deployed.
It is also possible for an embodiment to be provided with parking sensors and the sensors may in turn automatically generate a demand for braking. In an embodiment, a second mode of braking would be identified in response to a command for braking being generated by a parking sensor.
As previously stated, a subsystem 2907 is provided for the identification of faults. In the embodiment, the second mode of braking is identified in response to entering a modified driving condition following the detection of a fault. Thus, a fault may be encountered and a driver may be informed that the vehicle requires attention although some further driving is allowed in order for the driver to reach a safe parking location or to reach a location where the vehicle may be serviced. Under these situations, operation of the vehicle is modified (possibly restricting speed) until the repairs have been performed. In an embodiment, part of this modification may involve disabling the regenerative braking system and relying exclusively upon mechanical braking.