DE102012209645A1 - Method for controlling the charging operation in an electric motor vehicle - Google Patents

Abstract

Method for controlling the charging operation of a battery (3) in an electric motor vehicle (1) assigned to an electric motor (2), wherein a target charge state lying below a maximum charge state of the battery (3) is determined as a function of an operation prediction information of the at least partially related operating section Motor vehicle (1) is determined and a charging of the battery (3) is limited to the Zielladezustand.

Description

The invention relates to a method for controlling the charging operation of an electric motor associated battery in an electric motor vehicle and an electric motor vehicle.

Electric motor vehicles, often also referred to as electric vehicles for short, are already known in the prior art. In contrast to conventional motor vehicles they are not operated by an internal combustion engine, but by an electric motor which is powered by a battery, in particular a high-voltage battery, as energy storage.

An important issue in such electric vehicles is the range, which is why it is trying to create batteries with ever larger capacity in order to increase the range of electric vehicles as possible. With the desire for a maximum range as possible, however, is also a heavy burden on the battery, after a high state of charge is detrimental to the life.

The invention is therefore based on the object to provide a way to control the charging operation of the battery so that with sufficient available energy in the battery still increases the life of the battery, in particular optimized.

To achieve this object, the invention provides that in a method of the type mentioned above, located below a maximum state of charge of the battery Zielladezustand is determined as a function of at least partially related to an imminent operating section operating forecast information of the motor vehicle and charging of the battery is limited to the Zielladezustand ,

So it is proposed an optimized operation management for a battery, of which also a battery pack should be included, in terms of the life of the battery. It has been recognized that the calendar aging of the battery strongly depends on the current voltage or the current state of charge of the battery. This applies in particular to lithium-ion batteries or cells with oxide cathodes. However, it is also generally true that the aging is correlated with the state of charge of the energy store or the single cell. Basically, it can be said that the higher the state of charge of the battery, in particular so the higher the voltage of the battery, the higher the aging of the battery is.

It should also be noted that there is a cycle aging in batteries, which is dependent on the so-called cycle depth, that is, the electrical energy taken from the battery or discharged into the battery per discharge / charge process. If this is reduced, then a higher number of cycles (and thus a longer service life) can be realized. This is disproportionate, d. that is, the total electrical energy turnover through the battery over the lifetime increases significantly with less cycle depth.

Consequently, the present invention proposes that the battery is not always charged to a maximum state of charge, which is usually definable by certain conditions, but the charge of the battery is limited to a below the maximum state of charge target charge state, if it can be determined that a larger amount of energy in view of the now following operation of the motor vehicle is no longer required. For this purpose, an operation prediction information is evaluated, which relates in particular, but not necessarily completely, to an immediately imminent operating section, so that information about the amount of energy actually required in the near future and hence a destination load state can be derived therefrom. In the context of the present invention, an operating section may, in particular, be understood as an operating section concluded with a renewed charging process (mains charging process), in particular an operating section concluded with a renewed charging process at a charging station. In this type of imminent operating sections in particular a use of the motor vehicle for the driving operation is given. It is also conceivable, however, an imminent operation section, which concerns a stay at the charging station until a further trip, which will be discussed in more detail below. Likewise, the upcoming operating section may be a section in which the motor vehicle is not used for a certain time.

By limiting the charging of the battery in view of predicted future operating conditions, the method according to the invention thus makes it possible to extend the service lives of batteries, in particular with regard to calendar aging, but also with regard to cycle aging. Thus, additional information is used to enable the durability of the battery-friendly operating strategy.

In an advantageous embodiment of the present invention, it may be provided that the destination charge state is determined as an operating section that is imminent for the imminent recharge process Energy requirement plus a safety value is determined. If, for example, it is known that the motor vehicle will travel a certain distance, a previously at least approximately known amount of energy, the energy requirement, is required for it. This energy is therefore minimal required to cover the distance can. However, the invention proposes to use a safety margin in the form of, for example, fixed safety value, which gives the operator of the motor vehicle psychological security to meet the requirements of his driving requirements. It is conceivable, in addition to a fixed, predetermined safety value but also to use a dependent on the energy demand safety value, for example, set up a percentage. On this basis, the target charge state up to which the battery is charged to the maximum is determined.

It may further be provided that the target charge state is also determined taking into account regenerative components of the immediately preceding operating section, in particular with regard to an energy absorption capability of the battery. Thus, it is possible, for example, that a regenerative operation of the motor vehicle, for example when driving downhill, in which electrical energy is generated via the electric generator, must be taken into account. However, this can be done not only in terms of energy requirements for a certain distance, but also in terms of capacity of the battery itself. For example, there may be a case in which a motor vehicle at the beginning of the operating section is initially charged regeneratively, for example, by driving down a mountain and generating electricity accordingly. To be able to absorb this in the battery, the state of charge of the battery at the beginning must not be 100%, thus correspond to the maximum charge state. Rather, depending on the amount of current to be injected and the amount of energy to be injected, a state of charge must be selected (the target charge state) that allows the supply of the predicted amount of energy at the expected current. In this way, even a double optimization of the charging operation of the battery is possible because on the one hand, the Zielladezustand is less than the maximum state of charge, on the other hand, it ensures that the energy generated by regenerative feeding can be largely absorbed by the battery as energy storage.

In a further advantageous embodiment of the present invention can be provided that the Zielladezustand is also determined or adjusted depending on an outside temperature. Specifically, it can be provided that a higher Zielladezustand is determined with decreasing outside temperature. Depending on the outside temperature of the Zielladezustand the battery can be chosen and set differently, because it is taken into account the realization that with the same drive performance (operating performance) a larger amount of energy at lower outside temperature is needed. This is based on the one hand in the internal resistance of the battery, after an increase in the internal resistance causes higher losses and the like. In addition it comes that possibly only a smaller achievement to the drive, concretely the electric motor, can be discharged and / or the lower cut-off voltage of the battery is reached faster. Finally, at lower temperatures, statistically more energy will be used from the battery for heating and air conditioning purposes. For example, to account for the outside temperature, it may be provided that a value for the energy requirement per kilometer traveled is adjusted as a function of the outside temperature, but other possibilities are also conceivable for adapting the target load state to the outside temperature, for example by subsequently adapting a calculation result and the like.

The outside temperature can be determined via a measuring device of the motor vehicle itself. A value derived from a previous journey and recorded there by measurement can also be used. However, it is also conceivable to use other sources of information, for example if the motor vehicle has access to data from an external measuring device or even, at least during the connection to a charging station, is connected to a network, in particular the Internet. Then, in general, an expected or current outside temperature can be retrieved via a communication connection from an external information source, in particular the Internet. In this case, a statement about the expected outside temperature can be derived from a weather forecast or other prediction and transmitted to the battery controller.

In this context, it should be noted that, as known in the art, there are basically several approaches to determine a current state of charge of a battery and thus to allow compliance with the Zieladeleverts. For example, in the case of batteries with oxide cathodes, it is known that it is possible to deduce directly from the current battery voltage the current state of charge (frequently also SOC - state of charge). Then, in particular, the Zielladezustand can be determined in the form of a battery voltage. But also for other types of batteries ways are known to determine the current state of charge, for example, a meter for in the battery supplied and discharged from the battery charge (Ampèundundzählähler). Such a meter can whenever the maximum state of charge or a Minimum charge state is reached, calibrated accordingly to avoid cumulative errors in the operation as possible. In general, the ampere-hour meter is the simplest type of energy balancing in a battery. Examples of batteries in which such a meter can be used as a central element are batteries with iron phosphate cathodes or titanate cathodes. However, other methods known in the prior art for determining a current state of charge in the method according to the invention can of course also be used.

The operation prediction information can be determined in different ways in the context of the present invention. For example, it is conceivable that the operating prediction information is determined from an input of an operator of the motor vehicle. In this case, there is an interface to the operator through which the operator can enter certain expected usage scenarios. Based on this information, the battery of the motor vehicle is gently, for example, not completely charged, so that the life is extended.

Additionally or alternatively, however, it is also conceivable that the operating prediction information is determined from operating data of the past and / or operating data about planned journeys. In this case, therefore, the history and / or planning information is evaluated in order to make predictions for the future.

Specifically, it can be provided that the operating prediction information is determined by inputting a predetermined operating scenario by an operator or is determined from a predetermined by a user to be traveled route, in particular using navigation data of a navigation system. Thus, it is possible for a user to specify a rough, in particular predefined, usage scenario for the next operating section, for example an approximate route or the like. For this purpose, the user, for example, on a man-machine interface, several options can be offered. However, it is also advantageous if the operating prediction information is determined from a route specified by a user to be traveled. If, for example, it is known how the motor vehicle should travel to which destination during the next operating section for which it is being loaded, it can then be estimated in order to determine the destination load state which energy requirement actually exists for this route. In this case, a navigation system can provide further information, for example about inclines and slopes, in order to enable an even more accurate evaluation with regard to the destination charge state. Such estimates are already known, for example, from the field of range calculation based on navigation data in principle.

In a particularly advantageous embodiment of the present invention can be provided that the operating data of the past are analyzed for recurrent consumption patterns, in particular daily and / or weekly and / or monthly repeating journeys and / or consumption. Thus, a logic can be provided which can predict a normal operating state, for example, on the basis of the day, from the history, the operating data, by carrying out corresponding analyzes with regard to temporal patterns.

Furthermore, it is expedient for the operating data for daily and / or weekly and / or monthly repeating journeys and / or other journeys planned for a particular appointment to be called up via a communication connection, in particular the Internet, from a source external to the motor vehicle, in particular a calendar application , As already mentioned with regard to the outside temperature, so also external information source can be used, in particular communication links to the Internet, which exist in general or during the charging operation. In particular, a link with a personal calendar application, ie software, of the user is possible to determine information about past and planned trips. This can be done from direct entries, but also by derivation, for example, from the existence of appointments at certain locations. Thus, a "coupling" of an electronic calendar with the battery control, in this case specifically the control of the charging operation, proposed.

In the context of the method according to the invention, it is expediently possible, in the case of fully automatically determined operating forecast information, to change this as a function of user input with regard to at least one imminent operating section. The user can therefore at any time bring about an operation with an input in advance, if he wants to give up the optimized mode of operation in favor of, for example, an optimized range in each individual case. Thus, if another functionality would be desired, for example a larger range requirement exist in the individual case, the function realized according to the invention can be switched off at any time at least temporarily in advance or be adapted to the larger range requirement accordingly.

In a particularly advantageous embodiment of the present invention, it can be provided that as operating forecast information In particular, a period comprehensive holiday information is determined, in particular by actuation of at least one operating element by an operator of the motor vehicle. In this embodiment of the present invention, it is therefore conceivable to determine a specific operating prediction information that indicates the remaining of the motor vehicle at the charging station for a certain period of time, so that the charging and in particular unloading operation can be adapted in this knowledge. It can expediently be provided that a predetermined, between the maximum charge state and a minimum charge state lying, in particular exactly half of the maximum charge state amounts amount, medium load state is used as Zielladezustand in the presence of a holiday information. The battery is thus, if a use of the motor vehicle for driving is not provided anyway, spent in a medium state of charge as Zielladezustand in which it is exposed to a much lower aging than the maximum state of charge. In addition, if the battery is held in the mid-charge state, there is no danger of massive damage to the battery, for example due to a deep discharge in the empty state of the battery. For if the state of charge of the battery falls below a minimal charge state, in particular, the battery voltage below a minimum voltage, it can lead to irreparable damage to the cells, which makes replacement of the cell or battery necessary, and the like. Such a risk is avoided in the "holiday business" described here.

It is also particularly advantageous if in the presence of non-use information about the imminent non-use of the motor vehicle for driving, in particular holiday information, the battery is operated to a power supply connected to a supporting energy supply and / or energy consumption, the state of charge of the battery remains within a given target interval. So if a battery is provided with bi-directional network connection, the presence of the non-use or holiday information can cause the battery for the given period (reinforced) is used for network services. Here, an interaction of a battery control device with a control unit of the charging station can be provided in the context of an extended battery management. But even in this case, attention is paid to an optimum range of the state of charge, which can be determined as a function of the battery chemistry. In this way, the aging of the battery is minimized. Another advantage is that the battery in this state can perform or record the highest possible power in both directions. In this case, a target interval between 10 to 40% of the maximum charge state and 50 to 95% of the maximum charge state, preferably between 20 to 30% of the maximum charge state and 60 to 90% of the maximum charge state, depending on the battery, its chemical electrode composition and thus their aging behavior. For example, so the control can be such that the state of charge of the battery always moves between 20 and 70% of the maximum state of charge.

It should also be noted at this point that the input of the non-use information as operating prediction information is expediently linked to the actuation of at least one operating element by an operator of the motor vehicle, so that such an operating element can be referred to, for example, as a "holiday button". Of course, a very user-friendly variant can be realized for example via a human-machine interface in the vehicle.

Furthermore, in an expedient embodiment of the invention, in the case of a further operating prediction information relating to an operating section after the period of non-use information, the battery is charged at the end of the time to a destination charge state corresponding to the further operating prediction information. It can therefore be provided that at the end of the period in which the motor vehicle is not required for driving, the battery is then brought back into a state in which it is suitably charged in order to fulfill a subsequent operating section as desired. If such further operation prediction information is not present, it can generally be provided that, at the end of the time duration, the battery is brought into a state in which it is held at the upper end of the optimal state of charge window, for which purpose a final charge state value can be fixed or determined.

The "holiday button" functionality described here can also be used, for example, for a public holiday, a weekend or the like.

In addition to the method, the invention also relates to a motor vehicle, comprising an electric motor, a battery associated therewith and a charging device controlling the battery of the control device, which is designed to carry out the method according to the invention. All statements relating to the method according to the invention can be analogously transferred to the motor vehicle according to the invention, with which therefore the advantages of the present invention can be obtained.

Further advantages and details of the present invention will become apparent from the The following described embodiments and with reference to the drawing. Showing:

1 a schematic diagram of a motor vehicle according to the invention,

2 a flow chart of the method according to the invention, and

3 a flowchart in the presence of a holiday information as operation prediction information.

1 shows a schematic diagram of a motor vehicle according to the invention 1 , This is an electric motor vehicle 1 with an electric motor 2 which has a battery 3 is assigned as energy storage. About a corresponding connection 4 can the battery 3 to charge to a charging station indicated here only 5 be connected.

Operation of the battery 3 , in particular the charging operation, is provided by a battery control device 6 controlled, which can also receive data from other vehicle systems, with a navigation system by way of example here 7 , an outdoor temperature sensor 8th and a human-machine interface 9 (MMI) are shown. The battery control unit 6 is designed for carrying out the method according to the invention, thus limiting the state of charge of the battery 3 to a target load state which is selected in accordance with operation prediction information, now with respect to 2 will be explained in more detail.

According to 2 gets in one step 10 First, the operation prediction information is determined. This contains in particular a statement about which operating section follows the charge now to be made. Once this is known, it can be determined from a Zielladezustand, which is based in particular on the actual energy required, thus the charging operation without functionality restriction to the largest possible life of the battery 3 to optimize.

The operation prediction information may be obtained in different ways, for example, based on an input from an operator of the motor vehicle 1 , in particular via the human-machine interface 9 , or even automatically, thus by the battery control unit 6 itself, by analyzing operating data of the past.

Here are some examples. Thus, operating prediction information can be determined, for example, based on a selection of a usage scenario, which is described for example by a desired range of coverage. Such range range can then be assigned a Zielladezustand, which is based on the upper end of the range. A more accurate calculation is possible if there is information about a journey to be carried out, in particular a distance to be traveled, as the operating prediction information until the next loading option. In this case, for example, from inputs of the operator in the navigation system 7 be concluded, so that to determine the Zielladezustands an energy demand in the manner of a range determination taking into account further navigation data of the navigation system 7 can be determined.

However, it is preferred that an automatic evaluation of operating data of the past by the battery control unit 6 is carried out. An analysis is carried out on temporal patterns, in particular on recurrent energy consumption patterns, which can be repeated daily, weekly or monthly, for example. In one example, if it is known that an operator drives to his workstation every business day, a corresponding estimation for the working days may be made.

Furthermore, via coupling, thus passing a communication connection, in particular via the Internet, which allows data retrieval, with an (electronic) calendar, ie a calendar application, as operating data reference data for daily trips, planned additional trips on special days and other information regarding the required range to be obtained. Pairing with a calendar can continue to give data over months and seasons. This can be concluded that an outside temperature and other operating conditions that could have an influence on the required state of charge of the battery.

Furthermore, coupled with a weather forecast and / or other information source, e.g. via Internet, the above outdoor temperature and weather information further specified.

It should be noted at this point that the current operating prediction and the current Zielladezustand a user, in particular via the man-machine interface 9 can be brought to the knowledge, so that it has a manual intervention possibility and, for example, can enter deviations from automatically determined operating prediction information and thus make appropriate adjustments. For example, an operator may set an increased range request. The operator thus remains master of the state of charge that he would like to find; In particular, he can also the one described here Disable optimization of charging control in terms of lifetime.

In one step 11 then the destination load state is determined from the operation prediction information. In this case, other parameters can be taken into account, which will be discussed below. The determination can be a simple assignment, but it is also possible that a more complicated calculation in the battery control unit 6 takes place. If, for example, a specific route to be covered in the next operating section is predefined as operating forecast information, the destination load state, as already indicated, can be determined as the energy requirement determined for the route plus a safety value, in particular a fixed safety value. Expected energy requirements can of course also be determined in other contexts, for example from past operating data and the like. The use of a safety value is intended to provide psychological certainty and to ensure that, in any case, the operating section can be carried out until recharging. In addition to a fixed safety value, it is also conceivable to set up a safety value which depends, for example, on the percentage of energy demand, and the like.

The calculation of the destination load state also takes into account regenerative shares of the imminent operating section. While these can already be included in an energy requirement, for example, derived from slope data, in any case in the sum, they can also be taken into account elsewhere, for example, by ensuring that, in principle, a sufficient storage capacity of the battery 3 for energy obtained in phases of regenerative braking. For example, if the next trip starts with a downhill run, energy will be generated from renewable sources. The destination charge state can now be determined so that in any case enough storage capacity of the battery 3 is available in order to absorb the amount of energy gained there.

Another parameter which is taken into account in the determination of the destination charge state in this exemplary embodiment is, for example, via the outside temperature sensor 8th gained outside temperature after it has an impact on energy consumption as well. The outside temperature can be taken into account, for example, by adjusting an energy value per kilometer, but in any case it is provided that a higher energy demand is estimated as the outside temperature decreases, and thus a higher target charge state is determined, which reduces the effects of lower outside temperature, for example the higher internal resistance and lower power output to the electric motor 2 , Takes into account.

In one step 12 During the charging process it is checked whether the destination charge state has already been reached. If this is not the case, it will be reloaded, step 13 , However, when the target charge state is reached, the charge is aborted, step 14 That means the state of charge of the battery 3 is limited to the destination load state. In this way, excessive charge states are avoided, thus increasing the life of the battery 3 elevated.

A special, in step 10 in particular user prediction obtainable operating prediction information is the holiday information. This indicates that for a certain, likewise enterable period of time the motor vehicle 1 not required for driving. It remains at the charging station during this time 5 connected. If such a holiday information before, several driving actions are provided according to the invention, by 3 be explained in more detail, the box 15 the present holiday information indicates.

The step 16 relates to the determination of the target charge state, in the present case a mean target charge state (middle charge state) being set as 50% of the maximum charge state. This ensures that battery aging is significantly reduced.

Somewhat modified is the procedure in step 17 namely, when the battery 3 so on the charging station 5 is connected to the mains, that this, for example via a control unit of the charging station 5 , also energy from the battery 3 can call. In this case, the middle charge state is at least temporarily canceled and the restriction is realized by the state of charge of the battery 3 in a target interval, in this embodiment, between 20% and 70% of the maximum state of charge, so that there is also a limitation that the life of the battery 3 increases after charging states near the maximum charge state are avoided.

If the end of the time period associated with the holiday information closes, a higher target charge state is again sought, which may correspond to a fixed destination charge state closer to the maximum charge state, but also due to information about a subsequent operating section, for example a route to be traveled. can be chosen. The control of the charging process via the battery control unit 6 then takes place so that with the completion of the period of time the new Zielladezustand is reached.

Although the invention has been further illustrated and described in detail by the preferred embodiment, the invention is not limited by the disclosed examples, and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Claims (17)

Method for controlling the charging operation of an electric motor ( 2 ) associated battery ( 3 ) in an electric motor vehicle ( 1 ), characterized in that one below a maximum state of charge of the battery ( 3 ) according to an at least partially related to an immediately upcoming operating section operating prediction information of the motor vehicle ( 1 ) and charging the battery ( 3 ) is limited to the destination load state.  A method according to claim 1, characterized in that the Zielladezustand is determined as a for the imminent, concluded with a recharging operation operation determined energy demand plus a safety value.  A method according to claim 1 or 2, characterized in that the Zielladezustand is also determined taking into account regenerative components of the imminent operating section, in particular with regard to an energy absorption capacity of the battery.  Method according to one of the preceding claims, characterized in that the target charge state is also determined or adjusted in dependence on an outside temperature.  A method according to claim 4, characterized in that with decreasing outside temperature, a higher Zielladezustand is determined.  A method according to claim 5, characterized in that an expected or current outside temperature via a communication link from an external information source, in particular the Internet, is retrieved. Method according to one of the preceding claims, characterized in that the operation prediction information from an input of an operator of the motor vehicle ( 1 ) and / or from operating data of the past and / or operating data about planned journeys. A method according to claim 7, characterized in that the operation prediction information is determined by inputting a predetermined operation scenario by an operator or from a predetermined by an operator, to be traveled route, in particular using navigation data of a navigation system ( 7 ), is determined.  A method according to claim 7 or 8, characterized in that the operating data of the past are analyzed for recurrent consumption patterns, in particular daily and / or weekly and / or monthly repeating journeys and / or consumption.  Method according to one of claims 7 to 9, characterized in that the operating data for daily and / or weekly and / or monthly repeating journeys and / or other planned for a specific date journeys via a communication link, in particular the Internet, from a motor vehicle external source , in particular a calendar application.  A method according to claim 9 or 10, characterized in that in a fully automatically determined operating prediction information this is changed depending on a user input with regard to at least one imminent operating section. Method according to one of the preceding claims, characterized in that as operating prediction information a non-use information of the imminent non-use of the motor vehicle for the driving operation is determined, in particular by actuation of at least one operating element by an operator of the motor vehicle ( 1 ).  A method according to claim 12, characterized in that is used as Zielladezustand in the presence of non-use information, a predetermined, lying between the maximum state of charge and a minimum state of charge, in particular exactly half of the maximum state of charge amount, medium state of charge. A method according to claim 12 or 13, characterized in that in the presence of non-use information, the battery ( 3 ) to an energy supply and / or energy intake supporting a power grid connected to it, the state of charge of the battery ( 3 ) remains within a predetermined target interval.  A method according to claim 14, characterized in that between 10 to 40% of the maximum state of charge and 50 to 95% of the maximum state of charge, preferably between 20 to 30% of the maximum state of charge and 60 to 90% of the maximum state of charge lying target interval is used. Method according to one of Claims 12 to 15, characterized in that, in the case of a further operating prediction information relating to an operating section after the period of non-use information, the battery ( 3 ) is loaded at the end of the time period to a target loading state corresponding to the further operation prediction information. Motor vehicle ( 1 ) comprising an electric motor ( 2 ), a battery associated therewith ( 3 ) and a charging operation of the battery controlling controller ( 6 ), which is designed for carrying out a method according to one of the preceding claims.

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