DE102013217092B4 - Method of operating a vehicle - Google Patents

Abstract

Method for operating a vehicle with a drive train comprising an electric machine (1), the drive torque of which can be delivered to an output (3), a driver type detection being carried out which, based on a number of parameters determined during operation of the vehicle, identifies a driver type (FT) is determined, which characterizes the driving style of the driver, one or more operating parameters of the vehicle being set as a function of the driver type (FT), a temperature (T) of the electric machine (1) being determined at one or more points in time and one or several parameters of the number of parameters depend on one or more determined temperatures (T), characterized in that the parameter or parameters which depend on the determined temperature or temperatures (T) depend on at least one determined temperature (T) and/or a temperature gradient (ΔT/Δt), which represents the change in the determined temperatures over time (T) represents.

Description

The invention relates to a method for operating a vehicle according to the preamble of claim 1.

In vehicles with an electric drive, the driving style of the driver is often determined with the aid of a driver type recognition and, based on this, the vehicle operation is controlled differently. The driver type is recognized based on certain parameters of the current operating status of the vehicle.

In the pamphlet DE 10 2004 023 512 A1 describes a method for energy management in an electrical energy system of a hybrid vehicle. During motor operation of the electric machine of the vehicle, a target state of charge of the electric energy store is defined, with which the electric machine is fed. The target state of charge depends on the driver type, which is determined by means of driver type recognition. The accelerator pedal actuation by the driver is included as a parameter in the driver type recognition, which is optionally weighted differently depending on the engine speed or the engine load.

In the pamphlet DE 10 2010 021 031 A1 a device for energy management in an electric vehicle is described, in which a driver type recognition is carried out depending on the discharging process of the electrical energy store, which supplies the electrical machine for driving the vehicle with energy.

Furthermore, the reference discloses DE 10 2009 042 180 A1 a method for operating a vehicle, wherein an operating strategy of the vehicle is determined based on a driving style of a vehicle driver and based on values of at least one operating parameter for a current route section and the determined operating strategy for an upcoming route section with similar route attributes is output as a recommended operating strategy. The recommended operating strategy is determined by evaluating the driving style and the values of the at least one operating parameter using statistical methods and comparing data on the driving style and the values of the at least one operating parameter stored in a short-term memory and in a long-term memory.

The object of the invention is to provide a method for operating a vehicle in which a driver type is identified simply and reliably and operating parameters of the vehicle are controlled based thereon.

This object is achieved by the method according to patent claim 1. Further developments of the invention are defined in the dependent claims.

The method according to the invention is used to operate a vehicle with a drive train that includes an electric machine whose drive torque can be output to an output. The vehicle is preferably a motor vehicle in the form of a car or truck. The vehicle can be a purely electric vehicle that is driven solely by the electric machine with energy from an electric energy store. The vehicle can also be a hybrid vehicle, which also includes an internal combustion engine in addition to an electric machine. The hybrid vehicle can be a parallel hybrid vehicle or a series hybrid vehicle or a power-split hybrid vehicle or a mixed form of these hybrid architectures.

Within the framework of the method according to the invention, driver type recognition is carried out, which determines a driver type, which characterizes the driving style of the driver, based on a number of characteristic variables determined during operation of the vehicle. Depending on the type of driver, one or more operating parameters of the vehicle and in particular of the drive train of the vehicle are set. The term driver type is to be understood broadly. In particular, in one variant, different categories of driver types (i.e. at least two driver types) can be processed, with a corresponding category being determined from these categories as part of driver type recognition. If necessary, however, the driver type can also be represented by a continuous range of values, with each value of the range of values being able to be regarded as a driver type within the meaning of the invention.

The method according to the invention is characterized in that an (absolute) temperature of the electrical machine is determined at one or more points in time and one or more parameters of the number of parameters depend on one or more determined temperatures. This means that the parameters themselves can optionally also represent the ascertained or ascertained temperatures. The term “one or more determined temperatures” is to be understood as meaning one or more temperatures of the electrical machine determined at the current operating time or at previous operating times. Depending on the configuration of the method according to the invention, the temperatures can be detected directly by a temperature sensor on the electrical machine. Nevertheless, the determination of the Temperatu can also be made via a calculation from other sensor data or via the power electronics software of the electrical machine. The method according to the invention is based on the knowledge that the temperature of the electrical machine provides very good information about the driving style of the driver. Accordingly, taking into account the temperature or variables dependent thereon, the type of driver can be suitably determined and corresponding operating parameters of the vehicle can be adjusted.

According to the invention, the parameter or parameters that depend on the determined temperature or temperatures directly include at least one determined temperature (e.g. the temperature at the current operating time) and/or a temperature gradient that represents the change in the determined temperatures over time. The concept of the temperature gradient is to be understood broadly and can include the change over time in any time intervals or also directly represent the chronological derivation of the temperature at the current point in time. Depending on the configuration of the method, the determined temperature and the temperature gradient can be taken into account together in a suitable manner when recognizing the type of driver. For example, a weighted sum may be defined that includes a temperature dependent addend and a temperature gradient dependent addend. The driver type is then determined via the value of the sum.

In a particularly preferred embodiment, the number of times the temperature gradient exceeds a gradient threshold value is counted in a predetermined time interval, with the count value resulting from the count being included in the determination of the driver type. A frequency threshold is preferably assigned to each driver type and the driver type is recognized as part of the driver type recognition according to the assigned frequency threshold which was last reached or exceeded by the count value at the end of the predetermined time interval. By taking into account the count value described above, the driver's driving style is taken into account in a suitable manner to determine whether he frequently requests a high torque for a short time, which is reflected in the temperature gradient of the electric machine.

In one embodiment, the frequency thresholds depend on an ascertained temperature and in particular the temperature at the current time in order to also suitably take into account the ascertained temperature or ascertained temperatures as part of the driver type recognition described above using frequency thresholds. In this case, the frequency thresholds are preferably set lower, the higher the ascertained temperature is.

If appropriate, there is also the possibility that the identification of the driver type takes place only via a determined temperature. For example, each driver type can be assigned a temperature interval from a plurality of adjoining temperature intervals, with the driver type being identified according to the assigned temperature interval in which the determined temperature of the electrical machine lies.

In a further variant of the method according to the invention, the drive train includes an automatically shifting transmission. The operating parameters of the vehicle are adjusted as a function of the driver type in such a way that a lower gear is engaged by the automatically shifting transmission in the event of a predetermined change in the driver type towards a driving style with higher driving dynamics. Analogously, if there is a predetermined change in the type of driver towards a driving style with low driving dynamics, a higher gear is preferably engaged by the automatically shifting transmission. The term driving dynamics is to be understood as a measure that reflects how sporty the driver drives and/or how dynamic the route or driving profile is, which is expressed in particular by how often power is briefly requested to drive the vehicle. Below are examples of how the driving dynamics can be defined as a function of the determined temperatures or the counter values described above. The speed of the electric machine is increased with the aid of the gear change just described of an automatically shifting transmission to a lower gear. This in turn has the consequence that, depending on the operating point of the electrical machine, the power loss in the electrical machine is lower and the increase in temperature of the machine is therefore also lower. As a result, the electric machine can be run longer or more frequently in the short-term power or overload range without temperature limits being exceeded. This takes account of the driver's desire for greater driving dynamics.

In a further embodiment of the method according to the invention, the operating parameters of the vehicle are set as a function of the driver type in such a way that in the event of a predetermined change in the driver type towards a driving style with higher driving dynamics, a predetermined maximum value of the positive torque of the electric machine and/or a predetermined Maximum value of negative spin amount torque of the electrical machine and/or a predetermined maximum value of the positive torque gradient of the electrical machine and/or a predetermined maximum value of the amount of the negative torque gradient of the electrical machine is reduced. The specified maximum values can be specified differently for positive torques or torque gradients than for negative torques or torque gradients. The specified maximum values must not be exceeded by the electric machine, which is taken into account by the control of the electric machine. In the event of a predetermined change in the driver type towards a driving style with less driving dynamics, a predetermined maximum value of the positive torque of the electrical machine and/or a predetermined maximum value of the absolute value of the negative torque of the electrical machine and/or a predetermined maximum value of the positive torque gradient is preferably also set analogously increased the electric machine and / or a predetermined maximum value of the amount of the negative torque gradient of the electric machine. With the variant of the invention just described, by reducing the maximum values of the torque or the torque gradient, it is achieved that the short-term power or overload of the electrical machine is available more frequently or for longer. In particular, hybrid vehicles can be driven purely electrically for longer without starting the combustion engine. This in turn takes account of the desire for greater driving dynamics.

In a further variant of the method according to the invention, there is a connection between a driver type and the above-described count of the exceeding of a gradient threshold such that increasing counts lead to driver types with higher driving dynamics. In a further specific embodiment, there is preferably a connection between a driver type and the ascertained temperatures of the electrical machine such that increasing temperatures lead to driver types with driving styles with higher driving dynamics.

In a particularly preferred embodiment of the method according to the invention, driver type recognition is carried out continuously during operation of the vehicle, so that the determined driver type and the setting of one or more operating parameters of the vehicle dependent thereon are continuously adapted. “Continuously” is to be understood as meaning driver type recognition at predetermined (small) time intervals. In this variant of the invention, it is ensured that changes in the driving style of the driver are recorded promptly and taken into account when operating the vehicle.

In addition to the parameters described above, which depend on the determined temperatures, other temperature-independent parameters that influence driver type identification can also be taken into account in the method according to the invention. Such a further parameter is preferably a driver's desired torque, which is determined in particular based on the accelerator pedal position of the driver. This parameter can, for example, be combined with the other parameters via a weighted sum.

In addition to the method described above, the invention also relates to a device for operating a vehicle with a drive train comprising an electric machine whose drive torque can be output to an output. The device includes a control unit which is designed in such a way that it carries out driver type recognition which, based on a number of parameters determined during operation of the vehicle, determines a driver type which characterizes the driving style of the driver. The control device is designed in such a way that, depending on the type of driver, it outputs commands for setting one or more operating parameters of the vehicle. The device is characterized in that one or more parameters of the number of parameters depend on one or more temperatures of the electrical machine, which are determined by the device at one or more points in time and/or are provided to the device. The device is designed to carry out one or more of the preferred variants of the method according to the invention described above.

The invention also relates to a vehicle with a drive train comprising an electric machine whose drive torque can be output to an output, the vehicle comprising the device according to the invention described above.

Exemplary embodiments of the invention are described in detail below with reference to the attached figures.

• 1 eine schematische Darstellung des Betriebs eines Fahrzeugs basierend auf einer Ausführungsform des erfindungsgemäßen Verfahrens, wobei die elektrische Maschine und das Getriebe des Fahrzeugs baulich getrennt sind; und
• 2 eine schematische Darstellung des Betriebs eines Fahrzeugs basierend auf einer Ausführungsform des erfindungsgemäßen Verfahrens, wobei die elektrische Maschine in das Getriebe des Fahrzeugs integriert ist.

Show it:

• 1 a schematic representation of the operation of a vehicle based on an embodiment of the method according to the invention, wherein the electric machine and the transmission of the vehicle are structurally separate; and
• 2 a schematic representation of the operation of a vehicle based on an embodiment of the method according to the invention, wherein the electric machine is integrated into the transmission of the vehicle.

The embodiments of the method according to the invention described below are described using an electrically driven motor vehicle. The motor vehicle can be a purely electric vehicle. There is also the possibility that the vehicle also includes an internal combustion engine in addition to an electric drive and thus represents a hybrid vehicle. It can be either a parallel hybrid vehicle or a serial hybrid vehicle.

In 1 an electric machine 1 is shown as a component of a motor vehicle, which is part of the drive train of the vehicle. Via an automatically shifting transmission 2 (eg via an automated transmission or an automatic transmission or a double-clutch transmission), the drive train delivers the drive torque of the electric machine to an output 3, which represents the drive wheels of the vehicle. Other components of the drive train are not shown. If the drive train is a parallel hybrid, for example, a clutch and an internal combustion engine follow in the direction of the dashed line L, which also generates drive torque when required by being coupled to the drive train. As further components are in 1 a power electronics system 4 and a transmission control unit 5 are shown schematically. The power electronics are used to control the electric machine 1 and the transmission control unit controls the automatic shifting of the individual gears of the automatically shifting transmission 2.

In the vehicle according to 1 an electrical energy store (not shown) in the form of a battery is also provided, via which the electrical machine 1 is fed. In a purely electric vehicle, the electrical energy store can be charged at an external charging station. In a hybrid vehicle, the internal combustion engine is used to charge the electrical energy store or the energy store is charged while driving through recuperation or load point shifting. In the case of so-called plug-in hybrids, the electrical energy storage device can also be charged via an external charging station.

In the embodiment of 1 the absolute temperature T of the electrical machine 1 is determined via a temperature sensor (not shown) on the electrical machine, with the temperature values being transmitted via a sensor cable (not shown) to the power electronics 4 and from there to a central control unit 6 . Instead of directly measuring the temperature, the temperature in the central control unit 6 or the power electronics 4 can also be calculated from other variables. The temperature values are recorded continuously at predetermined time intervals and processed by the control unit 6 in order to generate control commands from them. The central control unit calculates the temperature gradient ΔT/Δt based on the current and a predetermined number of past temperature values. As a rule, the control unit 6 also receives a large number of additional sensor data, from which it generates control commands, which is indicated only schematically by additional arrows which lead to the control unit or run out of it.

As part of the process of 1 is carried out by the control unit 6 based on the temperature gradient .DELTA.T / .DELTA.t driver type recognition, which characterizes the current driving style of the driver of the vehicle. It is essential to the invention that the determined temperatures T or the temperature gradient ΔT/Δt also flow into the driver type identification. In a preferred specific embodiment, driver type recognition proceeds in such a way that the frequency X is determined for a predetermined time interval with which the temperature gradient ΔT/Δt exceeds a predetermined gradient threshold value SW. A frequency threshold is assigned to each driver type FT, the driver type being recognized in the driver type recognition according to that assigned frequency threshold which the frequency X last reached or exceeded at the end of the predetermined time interval. Higher frequency thresholds stand for a driving style in which the driver requests brief torque more frequently when driving electrically, which is reflected in the higher number of larger temperature gradients in the electric machine.

In a modification of the driver type detection variant described here, the determined temperature T is also included in the determination of the driver type. The temperature can be taken into account, for example, in that the frequency thresholds assigned to the individual driver types are selected to be lower as a function of the determined temperature, the higher this temperature is. As a result, the driver type is also differentiated in terms of how high the base load of the electrical machine is according to the driver type.

The criteria of the temperature gradient or the absolute temperature can also be combined with one another in other ways. In particular, for example, a weighted sum ver be used, which includes a dependent on the frequency X addend and a dependent on the absolute temperature T addend, wherein a driver type is determined according to the size of the sum. If necessary, the driver type can also be represented by values from a continuous range of values and thus no longer represent a discrete category. In this case, the above frequency X can flow directly into the determination of the driver type without frequency thresholds having to be taken into account.

The aim of the driver type detection described here is now that the short-term power or overload of the electrical machine is available to the driver for a longer period of time or more frequently. To achieve this, in the embodiment of 1 corresponding commands C or C' are given to the power electronics 4 of the electrical machine 1 or the control unit 5 of the automatic transmission 2 depending on the recognized driver type FT.

If the driver type corresponds to a high temperature T and a high frequency X, the command C sets a specified maximum torque and/or a specified maximum value of the magnitude of the negative torque and possibly also a maximum value of a positive torque gradient and/or a specified maximum value of the magnitude of the negative Torque gradients of the electrical machine, which must not be exceeded during operation, are limited or reduced. The limitation preferably takes place so slowly that it is imperceptible to the driver. In particular, in a preferred variant, a maximum value for the limitation or reduction of the positive and negative maximum torque and/or the maximum value of the positive and negative torque gradient is also specified, which is 10%, for example. Hybrid vehicles or plug-in hybrid vehicles can therefore be driven purely electrically without a combustion engine for longer, which meets the driver's desire for a dynamic driving style.

In the embodiment of 1 the control unit 5 of the transmission 2 is also influenced by a command C'. In the case of a driver type classification, which stands for higher temperatures T or a high frequency X, a higher speed of the electrical machine is specified by selecting a lower gear in the automatically shifting transmission 2 . Due to the higher speed of the electrical machine, the power loss in the electrical machine is lower, depending on the operating point, and the temperature increase is therefore also lower. In this way, the electrical machine can be operated longer and/or more frequently at high loads in the short-term power or overload range without exceeding temperature limits. This also takes account of the driver's desire for greater driving dynamics.

In a preferred variant of the embodiment according to 1 In addition to the temperature gradient and the absolute temperature, the driver's desired torque, which is preferably determined via the detection of the gas pedal position, is also included in driver type recognition as a further parameter. This variable can be included in the driver type recognition, for example as a further summand in the weighted sum described above, comprising the frequency value X and the absolute temperature T. Furthermore, the driver type recognition is preferably carried out continuously by the control unit 6, ie at predetermined regular time intervals, as a result of which the control of the electric machine or the transmission is tracked adaptively if there is a change in the corresponding driver type.

2 shows an embodiment of the method according to the invention in a vehicle in which the electric machine 1 is integrated into the transmission 2 . The only difference between 2 and 1 is that the electric machine 1 and the transmission 2 are no longer designed as separate components in the drive train, but the electric machine 1 is a component within the transmission 2 . The control of the vehicle 2 runs analogously 1 away. 2 also shows the same components as 1 and designates them with the same reference numbers. In order to avoid repetition, therefore, reference is made to the description of the above 1 referred.

The embodiments of the method according to the invention described above have a number of advantages. In particular, for the first time the driver type recognition in an electrically powered vehicle based on the absolute temperature or the temperature gradient of the electric machine or parameters derived therefrom for controlling the operation of the vehicle and in particular the electric machine or the transmission is taken into account in order to thereby determine the driving behavior of the vehicle suitably adapted to the driving style of the driver.

Reference List

1

electric machine

2

automatic transmission

3

downforce

4

Power electronics of the electrical machine

5

Transmission control unit

6

central control unit

T

absolute temperature

ΔT/Δt

temperature gradient

SW

threshold

X

frequency

FT

driver type

C, C'

commands

L

line

Claims (12)

Method for operating a vehicle with a drive train comprising an electric machine (1), the drive torque of which can be output to an output (3), a driver type detection being carried out which, based on a number of parameters determined during operation of the vehicle, identifies a driver type (FT) determined, which characterizes the driving style of the driver, one or more operating parameters of the vehicle being set as a function of the driver type (FT), a temperature (T) of the electric machine (1) being determined at one or more points in time and one or several parameters of the number of parameters depend on one or more determined temperatures (T), characterized in that the parameter or parameters which depend on the determined temperature or temperatures (T) depend on at least one determined temperature (T) and/or a temperature gradient (ΔT/Δt), which represents the change in the determined temperatures over time (T) represents. procedure after claim 1 , characterized in that the exceeding of a gradient threshold value (SW) by the temperature gradient (ΔT/Δt) is counted in a predetermined time interval, the count value (X) resulting from the count being included in the determination of the driver type (FT). procedure after claim 2 , characterized in that each driver type (FT) is assigned a frequency threshold and the driver type (FT) is recognized according to that assigned frequency threshold which was last reached or exceeded by the count value (X) at the end of the predetermined time interval. procedure after claim 3 , characterized in that the frequency thresholds depend on a determined temperature (T) and are preferably set lower, the higher the determined temperature (T). Method according to one of the preceding claims, characterized in that the drive train comprises an automatically shifting transmission (2) and in the event of a predetermined change in driver type (FT) towards a driving style with higher driving dynamics from the automatically shifting transmission (2) a lower gear is inserted. Method according to one of the preceding claims, characterized in that in the event of a predetermined change in the driver type towards a driving style with higher driving dynamics, a predetermined maximum value of the positive torque of the electric machine (1) and/or a predetermined maximum value of the amount of the negative torque of the electric Machine (1) and/or a predetermined maximum value of the positive torque gradient of the electrical machine (1) and/or a predetermined maximum value of the amount of the negative torque gradient of the electrical machine is reduced. Method according to any one of the preceding claims in combination with claim 3 , characterized in that there is a connection between a driver type (FT) and the count value (X) such that increasing count values lead to driver types (FT) with driving styles with higher driving dynamics. Method according to one of the preceding claims, characterized in that there is a connection between a driver type (FT) and the ascertained temperatures (T) of the electrical machine (1) such that increasing ascertained temperatures (T) lead to driver types with driving styles with higher driving dynamics . Method according to one of the preceding claims, characterized in that driver type recognition is carried out continuously during operation of the vehicle, so that the determined driver type (FT) and the setting of one or more operating parameters of the vehicle dependent thereon are continuously adapted. Method according to one of the preceding claims, characterized in that the number of parameters also includes a driver's desired torque. Device for operating a vehicle with a drive train comprising an electric machine (1), the drive torque of which can be delivered to an output (3), the device comprising a control unit (6) which is designed in such a way that it carries out driver type recognition which is based on a number of parameters determined during operation of the vehicle determines a driver type (FT), which characterizes the driving style of the driver, with the control device during operation depending on the driver type (FT) issuing commands for setting one or more operating parameters of the vehicle, with one or more parameters of the Number of parameters depend on one or more temperatures (T) of the electrical machine (1), which are determined at one or more points in time by the device and/or are provided to the device, the device for carrying out a method according to one of Claims 1 until 10 is designed. Vehicle with a drive train comprising an electric machine (1) whose drive torque can be delivered to an output (3), characterized in that the vehicle has a device according to claim 11 includes.

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