WO2021155949A1

WO2021155949A1 - Route determination for an electric vehicle

Info

Publication number: WO2021155949A1
Application number: PCT/EP2020/053169
Authority: WO
Inventors: Suvendu RATH; Heejin JEONG
Original assignee: Bayerische Motoren Werke Aktiengesellschaft
Priority date: 2020-02-07
Filing date: 2020-02-07
Publication date: 2021-08-12
Also published as: EP4100698A1

Abstract

An electrically powered vehicle comprises an energy storage. A method for determining a route from a starting point to a destination point for said vehicle comprises steps of determining a first route from the starting point to the destination point; determining at least one search point on said first route, wherein the search points are placed such that an amount of energy required for the vehicle to travel from the starting point or one of the search points to a successive point along said first route is exceeded by a projected amount of energy stored in said storage when the vehicle is at said point; for each search point, determining at least one candidate point at which the energy storage may be charged; selecting one candidate point per search point; and providing a second route leading from the starting point over the selected candidate points to the destination point.

Description

ROUTE DETERMINATION FOR AN ELECTRIC VEHICLE

Present invention concerns the determination of a route. More specifically, present invention concerns determination of a route with recharging stops for an electric vehicle.

An electric vehicle comprises an energy storage of limited capacity. When the vehicle is intended to drive on a predetermined route from a predetermined starting point - often its current position - to some far-off destination point, it may run out of energy and break down on the way. The storage may be recharged at a charging station along the route. However, charging stations may not be found along said route so that an indirect route will be necessary. A charging station may be occupied or not provide a required service in terms of charging capacity or charging speed. Also, if more than one recharging stop is required, the original route may not present an optimal connection between stops.

It is therefore a task of present invention to provide an improved technology for determining a route for an electric vehicle that needs recharging on its way between a starting point and a destination point. The invention solves this object through subject matter of enclosed independent claims. Dependent claims give preferred embodiments.

An electrically powered vehicle comprises an energy storage. According to a first aspect of present invention, a method for determining a route from a starting point to a destination point for said vehicle comprises steps of determining a first route from the starting point to the destination point; determining at least one search point on said first route, wherein the search points are placed such that an amount of energy required for the vehicle to travel from the starting point or one of the search points to a successive point along said first route is exceeded by a projected amount of energy stored in said storage when the vehicle is at said point; for each search point, determining at least one candidate point at which the energy storage may be charged; selecting one candidate point per search point; and providing a second route leading from the starting point over the selected candidate points to the destination point. The first route may be determined by a navigation system or any other known routing means. The first route may be optimised for one or more cost parameters, comprising for instance travel time, required energy or travelled distance. Present method may allow adapting said first route such that the destination point can be reached with a minimum of recharging stops, a minimised detour from the first route or minimised recharging time. Selection of a recharging point may be based on one or more criteria so that recharging may be performed in the best possible way. A passenger of said vehicle may thus be only minimally affected by the requirement of a recharging stop. Acceptance for the electric vehicle may thus be raised.

The candidate point may be selected so that a length of the second route is minimised. Especially, candidate points of two successive search points may be chosen such that a route section connecting the search points is optimised in length.

The second route may be determined as the shortest of all possible routes that comprise the starting point, one candidate point per search point and the destination point. As there is only a predetermined maximum number of candidate points per search point, a number of possible routes connecting said starting point with said destination point over one candidate point per search point may be small enough to permit exhaustive search for the route with the minimum length. Optimisation of said second route may thus be maximal. Route determination may additionally be optimised by skipping unpromising candidate points that would lead to a longer route than one already determined so that route determination may be less resource-consuming.

For practical purposes, computation may require no more than standard hardware. Should a speed of determination or a quality of a provided solution prove insufficient, the method can easily be adapted for either option. By varying the number of candidate points per search point, the number of possible routes may be controlled. More candidate points may yield more possible routes and a possibly a better solution while less candidate points may permit faster determination of the second route. Said projected amount of energy may exceed said required energy at least by a predetermined amount. In other words, determination may be done such that there will be a predetermined minimum amount of energy left in the storage when the vehicle arrives at the next charging point or the destination point. This amount may be given as an absolute figure, e.g. 20 kWh, or relative, for instance with respect to a maximum capacity of said storage, e.g. 10 % of an exemplary capacity of 200 kWh of a given energy storage. The first search point may be determined somewhat differently, as will be explained in more detail below.

A successive search point to a predetermined search point may be determined by applying a certain predetermined range towards the destination point. Said range may be measured from a point that lies on said first route in at least a predetermined distance towards the starting point from said search point. In one realistic example, said predetermined distance may lie around 30 km. That is, 30 km back along the first route from one given search point an intermediate point may be determined, and a successive search point may be determined within in a predetermined maximum range of the vehicle from the intermediate point along said first route towards the destination point. Figuratively, it could be said that the successive search point is found with a pilgrim’s step approach, making one step backwards and two steps forward. Search points may be determined iteratively or recursively from said starting point onwards. For determination of the first search point, going back along the first route is not possible, so for the first search point the predetermined range may be measured directly from the starting point. A safety buffer may be considered to make sure the first search point can be safely reached.

A candidate point may be determined in an area of a predetermined length, extending from the search point towards the starting point, and a predetermined breadth, preferably measured with respect to the first route. It has proven advantageous to select a length of approximately 60 km. A breadth of approximately 10 km may yield good results in a real-world situation.

In one preferred embodiment, a limited number of candidate points may be determined for a search point. Determined candidate points may best fulfil one or more predetermined quality criteria. The criteria may be weighted so that points where the vehicle’s energy storage may be recharged may be brought into an order that reflects their quality. The best few points in a list ordered by quality may then be used as candidate points. This allows flexible definition of candidate point selection criteria. Determined candidate points may already represent favourable choices so that the finally determined second route may satisfy high requirements.

A first criterion may comprise a type of charging offered at the candidate point. The best type of charging may be HPC (high power charging), followed by DC (direct current) and finally AC (alternating current). Other types of charging may also be available and associated a quality rating. The first criterion may be weighted highest.

A second criterion may comprise a status of occupation of a recharging facility at said point. Should the charging facility at the point in question be available, the point’s quality may be deemed higher than if the facility is unavailable. For determination of availability, a projected time when said vehicle will require recharging services may be considered. This criterion may be weighted less than above-mentioned first criterion.

A third criterion may comprise a point’s distance to the search point. In this, the Euclidian distance of a distance along a road or on a road network may be considered. This criterion may be weighted less than above-mentioned first and/or second criteria.

Said first route may be made of a series of sections, wherein each search point may be determined such that it lies at a junction of two sections. This reflects known standard routes determined with a standard routing algorithm. A route section may start or end where a road diverges or meets another road, so that there is a choice where to proceed to. Above-mentioned intermediate point may lie at a junction of two such sections. In one embodiment, the intermediate point lies at the next junction that lies at least the predetermined distance away from said search point. In another embodiment, the intermediate point lies at the z^th point (for a given z, e.g. the second point for z = 2) that lies on the first route at least the predetermined distance away from said search point, heading from said search point towards the starting point. According to another aspect of present invention, an apparatus for determining a route from a starting point to a destination point for an electrically powered vehicle with an energy storage is adapted to carry out a method disclosed herein. The apparatus may be disposed on board a vehicle or in an external location.

The apparatus may comprise processing means that are adapted to carry out a method disclosed herein or a part of said method. For this, the processing means may comprise a programmable micro computer or micro controller and the method may be expressed as a computer program product with program code means. The computer program product may be saved on a computer readable media. Features or advantages of the method may be transferred to the apparatus and vice versa.

According to yet another aspect of present invention, an electrically powered vehicle comprises an apparatus for route determination as disclosed herein.

According to one more aspect of present invention, a system comprises an apparatus for route determination as disclosed herein, wherein the apparatus is disposed remote from an electric vehicle; and there is provided communication means for transmitting the determined second route to the vehicle.

The invention will now be described in more detail, making reference to the enclosed figures, in which:

Figure 1 shows a system;

Figures 2-8 show different stages and aspects of a method.

Figure 1 shows a system 100 comprising an electric vehicle 105 and a device 110 that is remote to the vehicle 105. While the vehicle 105 is mobile, the device may be disposed at a predetermined location or be implemented as a server or service, possibly in a computer cloud. The vehicle 105 can be propelled using an electric engine 115 that runs on electric energy from an energy storage 120. The vehicle 105 is preferred to comprise a passenger vehicle, such as a motorbike, a passenger car, a truck or a bus. Operation of the propulsion system on board the vehicle 105 may be controlled by a control unit 125. There may be an apparatus 130 on board the vehicle 105, the apparatus 130 being adapted to determine a route the vehicle 105 may follow to take it to a predetermined destination. The apparatus 130 may be partly or fully integrated with the control unit 125. In one embodiment the apparatus 130 is adapted to output control signals for controlling the vehicle’s motion along the determined route, while in another embodiment the apparatus 130 is adapted to give instructions to a human driver of the vehicle 105. In this embodiment, an interaction system 135 may be provided for input and/or output from and/or to the human.

Capacity of the energy storage 120 is generally limited. The energy storage 120 may comprise a battery or an accumulator, and number or kind of charging / discharging cycles may affect longevity of said storage 120. It is therefore preferred to not fully discharge the storage 120 during normal operation of said vehicle 105. This may also bring along the advantage of having a power reserve in case something unforeseen happens to the vehicle 105 before the energy storage 120 can be recharged.

Recharging of the energy storage 120 usually requires connecting the vehicle 105 to a charging facility 140 via a physical interface 145. The charging facility 140 is generally connected to a power grid and may provide electric power in different types of charging. An ordinary charging facility 140 that may be intended for home or public use, may provide AC charging, which is limited in power and therefore may require a longer charging time for completely recharging the electric storage 120. A higher performance charging facility 140 may provide DC charging; this kind of facility may be found in professional environments like for industrial use or at a commercial recharging station. An even higher performance way of charging the facility 140 may provide is HPC (High Performance Charging), which may offer charging power up to several 100 kW at voltages exceeding 100 V. With HPC, completely recharging the storage 120 on an HPC charging facility 140 may be a matter of minutes.

Some of the functionality of above-mentioned apparatus 130 may also be carried out by the device 110. Said device 110 may comprise a control unit 150 and an optional storage 155, which may especially be adapted to hold map data. A communication unit 160 may be provided and adapted to communicate with a corresponding communication unit 160 on board of said vehicle 105. The communication unit 160 may especially utilise a public wireless network like a mobile data or telephone network.

It is proposed that a route for the vehicle 105 is determined so that a necessary recharging stop is planned at an optimal position. Planning of a recharging stop may become necessary if an intended destination cannot be reached in one go due to insufficient energy in the vehicle’s energy storage 120.

Figure 2 shows a route 200 leading from a starting point 205 to a destination point 210. The route 200 is usually composed of nodes N and legs L connecting the nodes. Here, the starting point 205 has index 0 (zero) and is denoted N O, while the destination point 210 has index n and is denoted N_n. The nodes successive to index 0 will be 1 , 2, 3 etc., while the nodes preceding index n will be n-1 , n-2 and so forth. A broken line indicates that the absolute number of nodes in the route 200 may be arbitrary as long as there is at least a starting point 205 and a destination point 210. A leg L will have the same index as the node N it starts from; for instance, L_0 extends from N O to N_1 . Each leg L may be associated with additional information like its length, an incline or descent, an estimated energy required for the vehicle 105 to travel it etc.

The route 200 may be determined by an arbitrary navigation or route planning tool. As the provided route 200 needs to be travelled by a vehicle 105, it is generally defined on a street network. It is common that nodes N are chosen where streets of the network intersect, so that there is a chance for said vehicle 105 to follow the route 200 or diverge from it. Should the vehicle 105 diverge from a predetermined route 200, a new route 200 may be determined.

For discussing present invention, it is assumed that said route 200 is significantly longer than the distance the vehicle 105 can travel on energy contained in its storage 120, so that it will be necessary to introduce two or more recharging stops between starting point 205 and destination point 210. Should only one recharging stop be necessary, the proposed method may determine just one first stop. The general operation of present method comprises a first phase, in which search points 215 along the route 200 are determined. The search points will be close enough to one another - and to the starting point 205 and the destination point 210 - to permit the vehicle 105 to travel from one point to a successive point without recharging the storage 120 on the way. In a second phase, a charging facility 140 will be selected for each of the search points 215. For this, it is preferred to determine one or more candidate points 220 (not shown) in the vicinity of each search point 215, wherein each candidate point 220 represents a charging facility 140. Then the best candidate points 220 will be selected to determine an adapted route 225 (not shown) that starts from the starting point 205, leads over the selected candidate points 220 and ends at the destination point 210. In present discussion, reference is made to nodes N of said route 200 in determining various points so that they coincide with nodes N. However, in some embodiments not all of the determined points must coincide with a node N.

In the first phase, a first search point 215 is determined. For this, travel costs along the route 200, starting from the starting point 205 and moving towards the destination point 210, may be summed up until a predetermined distance is reached. Travel costs may be expressed as distances and the predetermined distance may be DRERM, a Displayed Remaining Range in Meters. This distance may be an internally determined remaining range of the vehicle 105 that is displayed to a driver of vehicle 105. DRERM is preferred to honour a predetermined safety gap so that an effective range of the vehicle 105 may be larger than DRERM.

The last node N before the sum of the leg distances is exceeded may be chosen as a first search point 215 with index m. This approach may be expressed as:

In this, 0 < m < n; and DRERM is a distance the vehicle 105 may travel using power stored in energy storage 120 when the vehicle 105 commences its trip at starting point 205. Figure 3 shows the route 200 in a later stage of presently proposed method.

From the first search point 215, a successive starting point 215 may be determined. This may be done recursively until the destination point 210 is reachable from the last determined search point 215. In order to determine a next search point 215 with index o, an intermediate point with index i may be determined. Intermediate point N_i is preferred to coincide with a node N and may be determined by virtually travelling the route 200 from the previously determined search point N_m backwards, heading to the starting point 205, until a predetermined distance is reached. For determining the accumulated distance, distances of travelled legs L may be summed up. The predetermined distance may for instance be about 30 km. After the predetermined distance is exceeded, one additional leg towards the starting point 205 may be travelled. The determined node will be the intermediate node N_i. Search for the intermediate node N_i may be expressed as: Dmin

In this, 0 < s < m; and Dmin may be the above-indicated 30 km or another predetermined distance. In figure 3, an exemplary intermediate point N_i is shown as a hollow circle with a bold line.

Figure 4 shows determination of search point 215 with index o successive to the search point with index m, starting at the previously determined intermediate point with index i. For this, the route 200 is virtually travelled starting from intermediate point N_i, heading towards the destination point N_n, thereby summing up distances between travelled legs L. Travelling stops when the sum has exceeded another predetermined distance that will here be called D(Cmin). The last node that can be reached from N_i without exceeding D(Cmin) may then be chosen as the next search point 115 with index o.

Said distance D(Cmin) may represent a practical range of said vehicle 105 and be determined on the basis of a state-of-charge of energy storage 120 at N_m. It may be assumed that the storage 120 has been recharged at N_m, so that the state-of-charge at N_i may be 100%. If the storage 120 could not be fully replenished, its state-of-charge may be lower than that.

It may not be intended to use up all the energy in the storage 120 for travelling along said route 200; instead, a predetermined reserve Cmin may be kept in the storage 120. The reserve may be expressed in absolute, i.e. in kW or in its equivalent in distance that may be travelled using the amount of energy, or relative, especially with respect to a maximum amount of energy that can be contained in said storage 120. In one embodiment, about 10% of the maximum storable energy is preferred to remain in the storage 120.

In mathematical notation this can be expressed as:

In this, i < m < o and D(Cmin) is a range the vehicle 105 may travel from previously determined search point 215 with index m.

Determination of successive search points 115 may be repeated until the destination point 210 lies within the range of vehicle 105 from the last search point 115. After this, the first phase may be completed and the route 200 may comprise a number of search points 115 on the route. Intermediate points may not be utilized any further.

Figure 5 shows an exemplary detail of said route 200 with two search points 115 with indices m and o. The shown search points 115 do not necessarily reflect the exemplary points discussed above. In the vicinity of each search point 115, a search area 505 is determined.

In present embodiment, a search area 505 extends from a search point 115 backwards along the route 200, that is, in a direction towards starting point 205. The search area 505 may have a predetermined breadth, e.g. ~10 km (5 km to each side of the route 200) and a predetermined length, e.g. ~60 km along the route 200. It can be seen that the search area 505 may follow a curve in route 200. Other shapes and/or sizes of search areas 505 may also be used.

Inside the search area 505, known charging facilities 140 may be determined. Each such facility 140 may be modelled as a candidate point 220 with a predetermined geographic position that matches the geographic position of the facility 140. Candidate points 220 are denoted C in figure 5 and indices comprise the index of the search point 215 they refer to (here: n or o) and a numerical index, starting from 1. For instance, C_o1 refers to a first candidate point 220 in a search area 505 comprising search point N o. Exemplary candidate points C are shown with a chequered fill in figure 5.

Not all charging facility 140 will be of the same use for vehicle 105. For instance, if the facility 140 is occupied at a time the vehicle 105 arrives, it may have to wait until the facility 140 gets available. A predetermined search filter may be applied to select only facilities 140 as candidate points C that fulfil a predetermined criterion. Flowever, there may be more than one criterion to be minded. Another possible criterion may be a distance of the facility 140 to the corresponding search point 215. The closer a candidate point C is to the search point 215, the smaller a detour for the vehicle 105 may be on the route 200. On the other hand, if a detour is made, choice of a successive or previous charging facility 140 may be affected so that the overall detour may be minimised.

In order to respect an arbitrary number of criteria for selection of a candidate point 220, as well as to limit candidate points 220 on which the final adapted route 225 will be determined on, it is proposed to determine a quality for each candidate point 220 and then select the best few candidate points 220 according to the determined quality. A candidate point’s 200 quality may reflect a position as well as a property of a corresponding charging facility 140.

Figure 6 shows exemplary qualities of candidate points C_o in figure 5. In a first column, a type of charging that is available at the charging facility 140 is expressed. FIPC is considered more preferable than DC, which is in turn considered more preferable than AC. Other types of charging and/or a different assignment of preferences may be employed. In a second column, a free / occupied status is shown. A depicted closed lock stands for an occupied charging facility 140 at a projected arrival time of the vehicle 105, while an open lock stands for an available charging facility 140. It is clear that a reservation may be made for an available charging facility 140 to be used with vehicle 105. A third column shows a geographic distance to the corresponding search point 215. Generally, a short distance will be preferred.

Each of the criteria corresponding to the different columns may be weighted to permit determination of an overall quality. Here, the first column has the highest weight, the second column a lower weight and the third column an even lower weight. Other weighting schemes may be chosen as desired. This quality is not numerically expressed in figure 6, but the candidate points C_o are exemplarily sorted according to their determined quality, with the highest determined quality in the topmost line. A selection 605 may comprise the best candidate points 220, with a predetermined limit to their number. Presently, the limit is chosen exemplarily as 3.

Figure 7 shows the detail of figure 5, reduced to the best few candidate points 220 for search points N_m and N o. Instead of search point N_m, candidate points C_m1 through C_m3 and instead of search point N o, candidate points C_o1 through C_o3 are shown. Between the search points 215, all possible connections are shown. Each candidate point C_o is connected to a successive point N_o+1 on the route 200, and each candidate point C_m is connected to a previous point N_m-1 on the route 200.

On all shown connections, a search may be conducted. Optimisation criterion may be the shortest overall time to travel from the starting point 205 to the destination point 210, including recharging time at the charging facilities 140. The final result is shown in figure 8. The determined adapted route 225 may be provided, for instance to a driver of vehicle 105. Provision may include turn-by turn instructions or an overview. Information may be presented for instance in graphical, written or symbolic form or as spoken text. Route 225 information may also be provided to a control unit that is adapted to control vehicle 105 in longitudinal and/or transversal direction. Reference Signs

100 system

105 electric vehicle

110 device

115 electric engine

120 energy storage

125 control unit

130 apparatus

135 interaction system

140 charging facility

145 interface

150 control unit

155 storage

160 communication unit

200 route

205 starting point

210 destination point

215 search point

220 candidate point

225 adapted route

505 search area

605 selection

Claims

1 . Method for determining a route from a starting point (205) to a destination point (210) for an electrically powered vehicle (105) with an energy storage (120), wherein the method comprises steps of: determining a first route (200) from the starting point (205) to the destination point (210); determining at least one search point (215) on said first route (200),

- wherein the search points (215) are placed such that an amount of energy required for the vehicle (105) to travel from the starting point (205) or one of the search points (215) to a successive point along said first route (200) is exceeded by a projected amount of energy stored in said storage (120) when the vehicle (105) is at said point; for each search point (215), determining at least one candidate point (220) at which the energy storage (120) may be charged; selecting one candidate point (220) per search point (215); and providing a second route (225) leading from the starting point (205) over the selected candidate points (220) to the destination point (210).

2. Method according to claim 1 , wherein the candidate point is selected so that a length of the second route (225) is minimised.

3. Method according to claim 2, wherein the second route (225) is determined as the shortest of all possible routes that comprise the starting point (205), one candidate point (220) per search point (215) and the destination point (210).

4. Method according to one of the above claims, wherein the projected amount of energy exceeds the required energy at least by a predetermined amount.

5. Method according to one of the above claims, wherein a successive search point (215) to a search point (215) is determined by applying a predetermined range towards the destination point (210) from a point that lies on said first route (200) in at least a predetermined distance towards the starting point (205) from said search point (215).

6. Method according to one of the above claims, wherein the candidate point (220) is determined in an area of a predetermined length, extending from the search point (215) towards the starting point (205), and a predetermined breadth.

7. Method according to one of the above claims, wherein a limited number of candidate points (220) for a search point (215) are determined that best fulfil one or more predetermined quality criteria.

8. Method according to claim 7, wherein the criterion comprises a type of charging offered at the candidate point (220).

9. Method according to claim 7 or 8, wherein the criterion comprises a status of occupation of a recharging facility at said point.

10. Method according to one of the claims 7 to 9, wherein the criterion comprises a point’s distance to the search point (215).

11 . Method according to one of the above claims, wherein said first route (200) is made of a series of sections and each search point (215) is determined such that it lies at a junction of two sections.

12. Apparatus (110, 130) for determining a route from a starting point (205) to a destination point (210) for an electrically powered vehicle (105) with an energy storage (120), wherein the apparatus is adapted to carry out a method according to one of the above claims.

13. Electrically powered vehicle (105) with an apparatus (110, 130) according to claim 12.

14. System, comprising an apparatus (130) according to claim 12, wherein the apparatus (130) is disposed remote from an electric vehicle (105); and communication means (160) for transmitting the determined second route (225) to the vehicle (105).