DE102022133573A1 - Bidirectional charging of an electric vehicle on a local grid - Google Patents

Abstract

The invention relates to a method (S1 - S5) for bidirectional charging of a drive battery (BAT) of an electric vehicle (2) which is connected to a charging point (9) of a local network (3), wherein the drive battery (BAT) is charged by means of a charging plan (S1, S4) and the user selects (S2) whether the charging plan (S1, S4) is designed for mobility planning (S1) or additionally or at least alternatively for flexibility planning (S4). The invention also relates to a system (1, 2, 11) with a property (1) and an electric vehicle (2), wherein a local energy network (3) of the property is connected to a public power supply network (5), at least one end consumer (6) and at least one charging point (9) set up for bidirectional charging of a drive battery (BAT) of the electric vehicle are connected to the local energy network (3), and by means of the system (1, 2, 11) a charging plan for the drive battery of the electric vehicle can be set up, which can be designed optionally for mobility planning or at least alternatively for flexibility planning.

Description

The invention relates to a method for charging a drive battery of an electric vehicle that is connected to a charging point of a local network, wherein the drive battery is charged using a charging plan. The invention also relates to a system with a property and an electric vehicle, wherein a local energy network of the property is connected to a public power supply network, at least one end consumer and at least one charging point set up for bidirectional charging of a drive battery of the electric vehicle are connected to the local energy network, and a charging plan for the drive battery of the electric vehicle can be set up using the system. The invention is particularly advantageously applicable to home networks of single-family homes.

The state of the art is spatial and temporal mobility planning for electric vehicles, EVs, directly in the vehicle or via apps, including planning of travel to, use of and reservation of charging points. This mobility planning does not have to be based exclusively on user input, but can also use other sources such as historical data, self-learning models, etc. to support the user in mobility planning by forecasting their needs. The mobility demand forecast can also be used directly as mobility planning. When a charging process begins, charging parameters for the newly started charging process are transferred from the electric vehicle to the charging point based on this mobility planning, provided digital charging communication (e.g. according to ISO 15118-2) is used. In the opposite direction, charging parameters (e.g. power limits) and incentives for a certain charging behavior can be transferred to the electric vehicle. A charging plan can then be created for the charging process, taking these parameters into account, by a planning device (which is integrated, for example, in the electric vehicle, the charging point or in a third party such as a home energy management system, HEMS). In the case of a bidirectionally enabled system, static technical limits (e.g. a minimum and/or maximum discharge current) are also communicated to the charging parameters. The process described, including the exchange of charging parameters, may be repeated several times during a charging process as part of "renegotiations" of a charging plan, especially if the framework conditions used when drawing up the currently valid charging plan have changed or could have changed.

From the perspective of energy technology applications, one weakness of classic mobility planning is that it only allows the user to provide information that is directly related to their mobility, e.g. departure times and the corresponding storage levels required. The mobility demand forecasts described also only include these parameters. Mobility planning is often based on recurring events, e.g. commuting every weekday from 7 a.m. with a distance of 25 km or similar. However, the actual usage behavior may deviate considerably from such mobility planning at certain times (home office phases, vacation times, etc.). This hardly poses a problem for unidirectional charging planning, which only takes into account charging the vehicle battery, since the usable energy flexibility of the individual charging process only depends on the next planned trip within a certain period of time (e.g. less than 48 hours). The performance of the charging planning or the very simple flexibility planning derived from it is then hardly affected.

In contrast, in a bidirectional system that allows charging and discharging (also known as V2X, e.g. including V2G, V2H, etc.), the usable flexibility increases essentially linearly with the length of the period until the planned departure time, even with very long connection times, since here the traction storage or drive battery can be used like a stationary battery storage system, e.g. included in a microgrid or home energy network. The usable flexibility can be the product of storage capacity and connection time in a particularly simple form. In another variant, the usable flexibility during a connection time can be understood as the difference between a maximum amount of energy that can be charged minus a minimum amount of energy that can be charged, in particular taking into account a target SoC to be reached at the time of departure and/or a minimum SoC that must not be undercut.

US11,413,984 B2 discloses an in-vehicle power system comprising: a charging-discharging device configured to selectively perform both a charging function for receiving and delivering a first power signal and a discharging function for transmitting a second power signal; a battery configured to store an electrical energy transmitted after DC conversion of the first power signal; and a charging-discharging control unit configured to control the charging-discharging device based on a user input or a predetermined control pattern.

US 2009/0140698 A1 discloses a method and apparatus that enables an end user enable the performance of a fully electric or hybrid vehicle and its charging system to be optimized for a desired operating mode. A system includes multiple charging/operating modes from which the user can select. Each charging/operating mode controls the cut-off voltage used during charging and the battery pack holding temperature.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art and in particular to provide an improved possibility of using bidirectional charging of an electric vehicle for effective use of electrical energy.

This object is achieved according to the features of the independent claims. Preferred embodiments can be found in particular in the dependent claims.

The problem is solved by a method for bidirectional charging of a drive battery of an electric vehicle that is connected to a charging point of a local energy network ("local network"), wherein the drive battery is charged by means of a charging plan and the user selects whether the charging plan is designed for mobility planning or at least alternatively for flexibility planning.

This method has the advantage that it is possible to specifically select whether an electric vehicle should be charged according to mobility planning and/or flexibility planning. This in turn means that the use of the drive battery as a buffer for flexibility planning can be adapted particularly precisely to periods that are not regularly intended for this purpose, e.g. vacation or home office periods, and in particular cannot simply be derived from mobility planning just because they are outside of normal connection and absence times, for example. The additional or exclusive selection of flexibility planning thus enables the usage goals desired by a user to be achieved more effectively, e.g. cost savings, _CO2 savings, etc. The user-side selection also practically excludes the possibility of incorrectly assigning flexibility planning to certain periods.

Bidirectional charging includes the ability to either charge or discharge an electric vehicle connected to a charging point. “Charging” therefore includes both charging and discharging.

Mobility planning is understood in particular to mean the creation of a charging plan from the point of view of meeting mobility requirements, such as the possibility of carrying out planned or probable future journeys of the electric vehicle. If the electric vehicle is charged according to a mobility plan, this can also be expressed as being in a "mobility mode". Use as an intermediate storage facility for the local energy network is optionally possible, especially in the case of long connection times, but is subordinate to the mobility requirements and thus only of limited effectiveness.

(Pure) flexibility planning is understood to mean, in particular, the creation of a charging plan (only) from the point of view of meeting the usage targets of an energy network to which the electric vehicle is connected via the charging point and for which it serves as an electrical buffer. If the electric vehicle is charged using flexibility planning, this can also be expressed as being in a "flexibility mode".

In both mobility planning and flexibility planning, certain boundary conditions for charging processes can be specified, e.g. by the electric vehicle, such as a lower limit of the charge level of the drive battery ("minimum SoC"), an upper limit of the charge level of the drive battery ("maximum SoC"), an operating point, operating times, power limits, limits for energy throughputs, etc. These boundary conditions can be different for the two modes: for example, the minimum SoC in mobility mode can be set higher than in flexibility mode, the permitted charging power in mobility mode can be set higher than in flexibility mode, etc.

The electric vehicle can be, for example, a plug-in hybrid vehicle, PHEV, or a fully electric vehicle, e.g. a battery-powered vehicle, BEV. The electric vehicle can be, for example, a passenger car, truck, bus, etc. or a motorcycle. The connection to the charging point can be made via a charging cable or inductively.

A local network is understood to be a local stationary energy distribution network that is connected to a public energy supply network and to which one or more electrical end users are connected, e.g. electrical devices. The local network can in particular be an energy distribution network of a property, e.g. a house, especially a single-family home. The local network can also be viewed or referred to as a "microgrid".

The charging plan includes in particular a load profile that is to be imposed on the drive battery. The charging plan can include one or more charging phases, one or more discharging phases and, if necessary, one or more rest phases without charging activity. The charging plan can be optimized with regard to one or more usage goals such as particularly battery-friendly charging, cost savings, _CO2 savings. The charging plan can be updated regularly (e.g. every 15 minutes or 1 hour) or triggered by events (e.g. with a change in an electricity tariff).

The fact that the charging plan is or can be designed for mobility planning or “at least alternatively” for flexibility planning means, in one embodiment, that the charging plan is or can be designed for mobility planning or alternatively for flexibility planning, and in another embodiment that the charging plan is or can also be designed for a mixture of these (“mixed mode”). The first case corresponds to the possibility that a user can switch the charging control between pure mobility planning and pure flexibility planning. One possible form of the mixed mode is that, e.g. time-controlled, switching takes place between mobility planning or mobility mode and pure flexibility planning or pure flexibility mode, possibly several times. This corresponds to “time multiplexing” between mobility mode and pure flexibility mode. Another possibility is that in mixed mode a certain proportion of the drive battery, e.g. virtually or consisting of certain cells, is managed in flexibility mode, the remaining proportion in mobility mode. Mobility mode, mixed mode and pure flexibility mode can together also be referred to as “planning modes”.

If the charging plan can be designed for a mixture of mobility and flexibility planning, it is an advantageous design to select the weighting with which the charging plan is designed for flexibility planning. This advantageously enables the choice of the extent to which mobility planning dominates the charging plan over flexibility planning, or vice versa. This in turn improves the adaptation of the charging plan to user requirements. This weighting can be done, for example, as part of a selection of “mobility planning only”, “mobility planning & flexibility planning” and “flexibility planning only” or even more finely graded, e.g. “mobility planning only”, “predominantly mobility planning”, “predominantly flexibility planning” and “flexibility planning only”. The different mixed modes can differ, for example, in the time-multiplex form through different proportions of time for mobility planning or pure flexibility planning, and in the form through battery distribution through different proportions of battery for mobility planning or pure flexibility planning.

It is a further development that the period for flexibility planning is open-ended or not limited and is only ended by a user action or another event such as a calendar reminder or similar. If a departure time is required to create the loading plan, this can then be specified so far in the future (e.g. 12/31/2099) that the flexibility mode initially runs practically unlimited.

One design is that if the charging plan is designed to be flexible, at least as an alternative, an end time is specified. This advantageously means that a separate conversion back or reactivation of the mobility planning can be dispensed with, which is particularly user-friendly.

It is a further development that when the charging plan is designed at least alternatively for flexibility planning, an end time is specified that corresponds to a departure time. This advantageously makes it possible for the charging plan to be set up in such a way that a user's mobility request is fulfilled at the departure time and consequently it is advantageously possible to return seamlessly to mobility planning. In other words, the boundary conditions for flexibility planning are adjusted - especially as soon as possible - shortly before the end specified by the end time so that the user's mobility request for the period after that is fulfilled at the end of flexibility planning. The departure time can be specified, for example, using a period in which flexibility planning is to be implemented.

It is a further development that a predetermined period of time (e.g. 6 h, 12 h, 24 h, 36 h or 48 h) before the specified end time of the flexibility planning period is automatically switched to mobility planning, in particular early enough so that charging to a desired or maximum state of charge (SoC) is possible.

The latter design can be implemented as follows: a user enters a period in which he would like to have flexibility planning implemented as an alternative to mobility planning, e.g. during a holiday period of three weeks. At the start of the holiday period, mobility planning is switched to pure flexibility planning. A specified period of time, e.g. 24 hours before the end of the holiday period, is automatically from flexibility planning to mobility planning, so that the user can drive to work with the electric vehicle as usual on the day after the end of the holiday period.

One design is that when the charging plan is designed (only or in addition) for flexibility planning, battery parameters are specified that reflect the user's minimum mobility requirements. This advantageously ensures that - especially if pure flexibility planning is selected beforehand - the electric vehicle can still be driven sensibly, e.g. to make unforeseen short trips, e.g. to a hospital, etc. This case can be useful, for example, if it is not planned to drive the electric vehicle during the flexibility planning period, but it cannot be ruled out, e.g. if the user is working from home for several days.

Alternatively, especially in the case of pure flexibility planning, it is possible to dispense with mapping a minimum mobility requirement of the user in order to achieve the most effective use of the drive battery as an intermediate storage device. This case can occur, for example, if the electric vehicle will definitely not be moved during the flexibility planning period, e.g. because all possible drivers are absent, e.g. on vacation.

One embodiment allows the user to make or be able to make their selection via an application program running on the electric vehicle and/or on a user terminal. This advantageously enables particularly simple input and implementation.

One embodiment is that the local network is equipped with at least one renewable energy generation system. This enables particularly cost-effective use of electricity. In addition, the drive battery can then be used particularly advantageously as an intermediate storage facility. The renewable energy generation system can be, for example, a photovoltaic system, a wind turbine and/or a geothermal system. One embodiment is that the local network is equipped with a stationary electrical energy storage system ("stationary storage system"), which can also be used as an intermediate storage facility. This enables particularly flexible and efficient control of electricity through the local network.

One design is that the local network is an energy network of a property connected to a public power supply network, especially a single-family home. This makes it possible for individual users to use electrical energy particularly efficiently.

One embodiment is that the charging plan is drawn up by the electric vehicle, the charging point, a home energy management system (“HEMS”) of the property, an external entity or any combination thereof. The external entity can, for example, be a network-based, appropriately configured, e.g. programmed, data processing entity such as a network server or a cloud computer. The external entity can be a backend system of a manufacturer of the electric vehicle.

One design feature is that the charging point is a wallbox.

• - ein lokales Energienetz der Liegenschaft an ein öffentliches Stromversorgungsnetz angeschlossen ist,
• - an das lokale Energienetz mindestens ein Endverbraucher und mindestens ein zum bidirektionalen Laden einer Antriebsbatterie des Elektrofahrzeugs eingerichteter Ladepunkt angeschlossen sind und
• - mittels des Systems ein Ladeplan für die Antriebsbatterie des Elektrofahrzeugs aufstellbar ist, welcher wahlweise auf eine Mobilitätsplanung oder zumindest alternativ auf eine Flexibilitätsplanung hin auslegbar ist. Das System kann analog zu dem Verfahren ausgebildet werden, und umgekehrt, und weist die gleichen Vorteile auf.

The task is also solved by a system with a property and an electric vehicle, where

• - a local energy network of the property is connected to a public electricity supply network,
• - at least one end consumer and at least one charging point set up for bidirectional charging of a traction battery of the electric vehicle are connected to the local energy network and
• - the system can be used to set up a charging plan for the drive battery of the electric vehicle, which can be designed either for mobility planning or at least alternatively for flexibility planning. The system can be designed analogously to the method, and vice versa, and has the same advantages.

One feature is that the property has a home energy management system, HEMS.

It is also possible for the system to have an external instance.

The object is also achieved by a system with a property connected to a public power supply network, to whose energy network at least one end consumer and at least one charging point set up for bidirectional charging of a drive battery of an electric vehicle are connected, wherein the system is set up to carry out the method as described above.

• 1 zeigt eine Skizze eines System mit einer Liegenschaft und mit einem Elektrofahrzeug; und
• 2 zeigt einen möglich Ablauf des Verfahrens zum bidirektionalen Laden einer Antriebsbatterie des Elektrofahrzeugs.

The above-described properties, features and advantages of this invention, as well as the manner in which they are achieved, will become clearer and more readily understood in connection with the following schematic description of an embodiment, which is explained in more detail in connection with the drawings.

• 1 shows a sketch of a system with a property and an electric vehicle; and
• 2 shows a possible sequence of the method for bidirectional charging of a drive battery of an electric vehicle.

1 shows a sketch of a system 1, 2, 11 with a property 1 in the form of, for example, a single-family home and with an electric vehicle 2 that is equipped with a drive battery BAT. The property 1 has a local energy network (“home network” 3) that is connected to a public power supply network 5 via an electricity meter, here: a so-called smart meter 4. Electrical devices or end users 6 such as household appliances, air conditioning systems, multimedia devices, lamps, motors, etc. can be electrically connected to the home network 3. In addition, at least one energy generation system such as the photovoltaic system 7 shown, a wind turbine, a geothermal system, etc. is connected to the home network 3, as well as, if necessary, a stationary electrical buffer (“stationary storage”) 8.

The home network 3 also has a charging point in the form of a wall box 9, to which the electric vehicle 2 can be connected via a charging cable 10. The electric vehicle 2 and the wall box 9 are set up for bidirectional charging of the electric vehicle 2. In addition, the electric vehicle 2 and the wall box 9 can communicate digitally with each other via the charging cable 10, e.g. in accordance with ISO 15118-2 and/or ISO 15118-20. Depending on the application, electrical energy discharged from the drive battery BAT of the electric vehicle 2 can be used to feed the end consumers 6 and/or charge the stationary storage 8 (V2H application case) and/or, if permitted, feed electrical energy into the public power grid 5 (V2G application case).

The electric vehicle 2 and the wallbox 9 are networked with an external entity in the form of a backend system 11, which can optionally also establish a data connection to a user's mobile user terminal 12, such as a smartphone, tablet PC, etc. The user terminal 12 is in particular a mobile user terminal such as a smartphone, tablet PC, etc. The backend system 11 can be connected to an energy aggregator, which can buy and sell electricity on an energy market, as well as to an energy supplier, which supplies the property 5 with electricity or electrical energy via the public power supply network 5 and bills the electrical energy that may have flowed bidirectionally via the smart meter 4 of a measuring point operator installed at the network connection point.

Property 1 also has a home energy management system (“HEMS” 13), which is communicatively linked to “smart” consumers 6, the photovoltaic system 7, the stationary storage system 8, the wallbox 9 and the backend system 11.

If there is a surplus of electrical energy (“solar power”) generated by the photovoltaic system 7 in the home network 4 (i.e. more solar power is generated than is consumed by the end users 6), the stationary storage unit 8 and then the electric vehicle 2 are charged with it. If the stationary storage unit 8 and the electric vehicle 2 are already charged, the surplus can - e.g. depending on legal regulations - be fed into the public power grid 5 in return for a feed-in tariff (V2G application case) or, if this is not permitted, the inverter of the photovoltaic system 7 can be turned down. If there is no surplus solar power available (i.e. the end users 6 consume more energy than is generated by the photovoltaic system 7), for example when the drive battery BAT is high, energy from the electric vehicle 2 can be fed back into the home network 3 (V2H application case) in order to minimize grid consumption from the public power grid 5, or can even be fed into the public power grid.

The HEMS 13 is responsible for controlling the power flows. In particular, the power flows can be optimized based on forecasts of costs, energy availability, environmental compatibility, etc. For this purpose, the HEMS 13 can, for example, receive information from the backend system 11 about electricity tariffs, feed-in tariffs, a _CO2 balance of the available electrical energy, etc. In one variant, the HEMS 13 also draws up a charging plan for charging the electric vehicle 2 and, if possible, takes into account not only the mobility requirements of the electric vehicle 2, but also tries to reconcile these with the optimization of the power flows in the home network 3. This is particularly effective if, as is the case here, the drive battery BAT of the electric vehicle 2 connected to the wallbox 9 can also be discharged and can therefore be used as an intermediate storage device.

At a user interface of the electric vehicle 2 and/or at the user terminal 12, a user can call up an application program (“app”), by means of which he can select a mobility mode for setting up a charging plan optimized for mobility planning or a flexibility mode for setting up a charging plan optimized for flexibility planning. In the following, it is assumed that only between a mobility mode and a (pure) flexibility mode without taking mobility wishes or habits into account.

2 shows a possible sequence of the procedure for bidirectional charging of the traction battery BAT.

It is assumed that in step S1, a mobility mode is initially activated and the HEMS 13 charges the electric vehicle 2 according to specified future routes, historical driving data, etc., optionally also using the drive battery BAT as a buffer for optimized power management in the home network 3, but the mobility requirements are prioritized above this.

In a step S2, the user can switch to a flexibility mode for a vacation period or similar during which he is absent and will not be using the electric vehicle 2. To do so, he can enter the flexibility mode together with a vacation period that can be entered by the user via the app.

In step S3, it is checked whether the start of the entered holiday period has been reached. If this is not the case (“N”), the HEMS 13 branches back to step S1 with the option of deleting the holiday period in step S2, entering a new holiday period, etc. In this case, mobility planning continues to be used as a basis for drawing up and updating the charging plans.

However, if the start of the holiday period is reached (“Y”), the HEMS 13 will then charge the electric vehicle 2 in accordance with the flexibility mode in step S4, not taking mobility requirements into account but using the drive battery of the electric vehicle 2 only as a (“quasi-stationary”) intermediate storage facility. This may include updating a charging plan.

In step S5, it is checked whether the end of the entered vacation period has been reached. If this is not the case ("N"), the system branches back to step S4 and the electric vehicle 2 continues to be charged according to the flexibility mode.

However, if this is the case (“Y”), the system branches back to step S1 and returns to mobility mode.

Of course, the present invention is not limited to the embodiment shown.

In general, “a”, “an”, etc. can be understood to mean a singular or a plural, in particular in the sense of “at least one” or “one or more”, etc., unless this is explicitly excluded, e.g. by the expression “exactly one”, etc.

A numerical value may also include the exact number stated as well as a usual tolerance range, as long as this is not explicitly excluded.

List of reference symbols

1

property

2

Electric vehicle

3

Home network

4

Smart Meter

5

Public electricity supply network

6

Consumer

7

Photovoltaic system

8th

Stationary storage

9

Wall box

10

Charging cable

11

Backend system

12

User device

13

HEMS

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions.

Cited patent literature

• US 11413984 B2 [0005]
• US 20090140698 A1 [0006]

Claims (14)

Method (S1 - S5) for bidirectional charging of a drive battery (BAT) of an electric vehicle (2) that is connected to a charging point (9) of a local network (3), wherein - the drive battery (BAT) is charged using a charging plan (S1, S4) and - the user selects (S2) whether the charging plan (S1, S4) is designed for mobility planning (S1) or additionally or at least alternatively for flexibility planning (S4). Procedure (S1 - S5) according to Claim 1 , in which the user selects (S2) whether the charging plan is designed for mobility planning (S1) or alternatively for flexibility planning (S4). Procedure (S1 - S5) according to Claim 1 , in which the user selects (S2) whether the charging plan is designed for mobility planning (S1), flexibility planning (S4) or a mixture of these. Procedure (S1 - S5) according to Claim 3 , which selects the weighting with which the charging plan is designed for flexibility planning. Method (S1 - S5) according to one of the preceding claims, in which, upon selection of the flexibility planning, an end time for the period of flexibility planning is specified (S2) and the charging plan is drawn up such that a predetermined mobility request of the user is fulfilled at the end time. Method (S1 - S5) according to one of the preceding claims, in which, when the charging plan is designed for flexibility planning, battery parameters are defined which reflect a minimum mobility requirement of the user. Method (S1 - S5) according to one of the preceding claims, in which the user makes his selection via an application program running on the electric vehicle (2) and/or on a user terminal (12) (S2). Method (S1 - S5) according to one of the preceding claims, in which the local network (3) is equipped with at least one regenerative energy generation plant (7). Method (S1 - S5) according to one of the preceding claims, in which the local network (3) is an energy network of a property (1), in particular a single-family house, connected to a public power supply network (5). Procedure (S1 - S5) according to Claim 9 , in which the charging plan is drawn up by the electric vehicle (2), the charging point (9), a HEMS (13) of the property (1), an external instance (11), in particular a backend system, or any combination thereof. Method (S1 - S5) according to one of the Claims 8 until 9 , where the charging point (9) is a wallbox. System (1, 2, 11) with a property (1) and an electric vehicle (2), wherein - a local energy network (3) of the property (1) is connected to a public power supply network (5), - at least one end consumer (6) and at least one charging point (9) set up for bidirectional charging of a drive battery (BAT) of the electric vehicle (2) are connected to the local energy network (3), and - a charging plan for the drive battery (BAT) of the electric vehicle (2) can be set up by means of the system (1, 2, 11), which can be designed either for mobility planning or at least alternatively for flexibility planning. System (1, 2, 11) according to Claim 12 , wherein the property (1) has a home energy management system (13). System (1, 2, 11) according to one of the Claims 12 until 13 , wherein the system (1, 2, 11) further comprises an external instance (11).