DE102022209046A1 - Method and device for controlling a current flow in a vehicle - Google Patents

Abstract

The invention relates to a method for controlling a current flow in a vehicle (50), the vehicle (50) having at least two electric drives (51, 52) and an energy storage device (53), the at least two electric drives (51, 52) and one The vehicle electrical system (54) is fed by means of the energy storage device (53) or feeds the energy storage device (53), with an energy storage direct current (I_Bat) being distributed between the vehicle electrical system (54) and the at least two electric drives (51, 52), each starting from a target torque (x.T_Des) or a target speed (x.n_Des) or target phase currents, target direct currents (x.I_DC_Des) are determined for the at least two electric drives (51, 52), and a direct current flow between the energy storage (53), the vehicle electrical system (54 ) and the at least two electric drives (51, 52) is divided in such a way that a maximum amount of an energy storage direct current (I_Bat_Lim) is not exceeded and that a target on-board electrical system direct current (I_Con_Des) is provided with the highest priority, with a resulting after provision of the target on-board electrical system direct current (I_Con_Des). Direct current is divided between the at least two electric drives (51,52) according to a predetermined prioritization ratio (AuxPrio) and the target direct currents (x.I_DC_Des) are limited if necessary. The invention further relates to a device (1).

Description

The invention relates to a method and a device for controlling a current flow in a vehicle.

As electrification in the transport sector progresses, commercial vehicles such as agricultural machinery are also increasingly being electrified. A particular challenge here is that, in addition to a main drive, there can also be a secondary drive that, for example, drives a PTO or hydraulics. It is particularly important to take into account the power or current limitation of a high-voltage battery in the vehicle.

The invention is based on the object of creating a method and a device for controlling a current flow in a vehicle.

The object is achieved according to the invention by a method with the features of patent claim 1 and a device with the features of patent claim 8. Advantageous embodiments of the invention result from the subclaims.

• - jeweils ausgehend von einem Solldrehmoment oder einer Solldrehzahl oder Sollphasenströmen Sollgleichströme für die mindestens zwei Elektroantriebe bestimmt werden, und
• - ein Gleichstromfluss zwischen dem Energiespeicher, dem Bordnetz und den mindestens zwei Elektroantrieben derart aufgeteilt wird, dass ein maximaler Betrag eines Energiespeichergleichstroms nicht überschritten wird und dass ein Sollbordnetzgleichstrom mit höchster Priorität bereitgestellt wird, wobei ein nach Bereitstellen des

Sollbordnetzgleichstroms resultierender Gleichstrom gemäß einem vorgegebenen Priorisierungsverhältnis auf die mindestens zwei Elektroantriebe aufgeteilt wird und die Sollgleichströme falls erforderlich begrenzt werden.In particular, a method for controlling a current flow in a vehicle is provided, wherein the vehicle has at least two electric drives and an energy storage, the at least two electric drives and an on-board electrical system being fed by means of the energy storage or feeding the energy storage, with an energy storage direct current being supplied to the on-board electrical system and the at least two electric drives are divided, for this purpose

• - Target direct currents are determined for the at least two electric drives based on a target torque or a target speed or target phase currents, and
• - a direct current flow between the energy storage, the on-board electrical system and the at least two electric drives is divided in such a way that a maximum amount of an energy storage direct current is not exceeded and that a target on-board electrical system direct current is provided with the highest priority, with one after provision of the

Target on-board network direct current resulting direct current is divided according to a predetermined prioritization ratio between the at least two electric drives and the target direct currents are limited if necessary.

• - jeweils ausgehend von einem Solldrehmoment oder einer Solldrehzahl oder Sollphasenströmen Sollgleichströme für die mindestens zwei Elektroantriebe zu bestimmen, und
• - einen Gleichstromfluss zwischen dem Energiespeicher, dem Bordnetz und den mindestens zwei Elektroantrieben derart aufzuteilen, dass ein maximaler Betrag eines Energiespeichergleichstroms nicht überschritten wird und dass ein Sollbordnetzgleichstrom mit höchster Priorität bereitgestellt wird, und einen nach Bereitstellen des Sollbordnetzgleichstroms resultierenden Gleichstrom gemäß einem vorgegebenen Priorisierungsverhältnis auf die mindestens zwei Elektroantriebe aufzuteilen und die Sollgleichströme falls erforderlich zu begrenzen.

Furthermore, in particular, a device for controlling a current flow in a vehicle is created, the vehicle having at least two electric drives and an energy storage device, the at least two electric drives and an on-board electrical system being fed by means of the energy storage device or feeding the energy storage device, comprising a control device, wherein the control device is set up to distribute an energy storage direct current to the on-board network and the at least two electric drives, and for this purpose

• - to determine target direct currents for the at least two electric drives based on a target torque or a target speed or target phase currents, and
• - to divide a direct current flow between the energy storage, the on-board electrical system and the at least two electric drives in such a way that a maximum amount of an energy storage direct current is not exceeded and that a target on-board electrical system direct current is provided with the highest priority, and a direct current resulting after the target on-board electrical system direct current has been provided in accordance with a predetermined prioritization ratio to divide at least two electric drives and to limit the target direct currents if necessary.

The method and the device make it possible not to exceed a limited power or a limited current with which the energy storage can be discharged or charged and to divide the existing power or current accordingly between an on-board electrical system and at least two electric drives. This is done on the basis of a target on-board electrical system current and target direct currents, which were determined for the at least two electric drives based on a respective target torque or a respective target speed or respective target phase currents (in particular in the form of target phase current vectors; some motor controllers provide target phase currents/current vectors). It is intended that the on-board electrical system is supplied first with the highest priority, since the on-board electrical system usually supplies important and in any case necessary control and/or monitoring devices. A direct current resulting after subtracting the target on-board electrical system current is then divided between the at least two electric drives according to a predetermined prioritization ratio. If the resulting direct current is sufficient for the at least two electric drives, both target direct currents are provided in full. However, if the resulting direct current is not sufficient, the prioritization is allocated according to the specified prioritization ratio. For this purpose, it is provided that the target direct currents are limited if necessary. As a result of such a limitation of the target direct current, the affected electric drive will then only run on the limited target direct current (or even not) operated and/or the limited target direct current is used to determine a (limited) target torque or a (limited) target speed or (limited) target phase currents, based on which the electric drive is regulated. It is noted that even when using a speed control, a target torque and/or target phase currents are ultimately derived from the speed controller (cascade control).

The method and the device control the current flow, in particular independently of an operating mode of the at least two electric drives. The current flow can be divided for both motor and generator operation. For this purpose, the direct currents are taken into account in particular with a corresponding sign, which indicates a direction of the power or current flow.

In particular, it can be provided that two electric drives are provided. Here, one electric drive can be, for example, a traction or main drive and the other electric drive can be a secondary drive, for example for a PTO or hydraulics. In particular, the two electric drives have a nominal power that is approximately the same. In principle, the nominal powers can also be of different sizes.

The vehicle is in particular a commercial vehicle, for example a tractor or other agricultural machinery. In principle, the vehicle can also be another land, rail, water, air or space vehicle, for example an air taxi or a drone.

The prioritization ratio includes in particular a specification that includes prioritization of the at least two electric drives. For example, if there are two electric drives, the prioritization ratio can be specified in the form of a value between 0 and 1 or a value between 0 and 100 (e.g. as a percentage). For the extreme values 0 and 1 or 0 and 100, one of the two electric drives is fully preferred (e.g. 0 = first electric drive; 1 = second electric drive), which means that if a resulting direct current is not sufficient for both target direct currents, only the one that is prioritized is given priority Electric drive is supplied and only when its target direct current can be fully provided is the remaining portion of the resulting direct current fed to the other of the two electric drives. With a value of 0.5, the resulting direct current is divided equally between both electric drives. If there are more than two electric drives, the prioritization ratio is determined accordingly, so that an order of prioritization and a ratio are determined in each case. For example, the first electric drive can be supplied with the highest priority, then the second electric drive, then the third electric drive, etc. Alternatively, for example, the first electric drive can be supplied with the highest priority, but then the remaining direct current is distributed to the second and second in a ratio of 50:50 divided into the third electric drive.

Parts of the device, in particular the control device, can be designed individually or collectively as a combination of hardware and software, for example as program code that is executed on a microcontroller or microprocessor. However, it can also be provided that parts are designed individually or combined as an application-specific integrated circuit (ASIC) and/or field-programmable gate array (FPGA).

In one embodiment it is provided that the target direct currents are determined based on the target torque or the target speed or the target phase currents using at least one characteristic map. In this way, a target direct current can be determined in a particularly simple and computing power-saving manner. The at least one characteristic map is in particular a characteristic space that maps a target torque, a battery voltage and an actual speed of the electric drive as input variables to a value for the target direct current. The at least one map can also be expressed in the form of a mathematical function, for example using a polynomial function. The characteristics are determined in particular by empirical series of tests on the respective electric drive on a test bench. In principle, simulations can also be used additionally or alternatively to determine a respective characteristic map.

In one embodiment, it is provided that a target direct current determined by means of the at least one characteristic map is converted into a target torque after dividing by means of an inverted map corresponding to the at least one characteristic map, based on which the respective electric drive is regulated.

In one embodiment it is provided that the prioritization ratio is or can be specified by a user of the vehicle using a control element set up for this purpose. This allows the user of the vehicle to specify which electric drive(s) should be given preference. With two electric drives, the control element can in particular be a sliding or Be a rotary control with which the prioritization ratio can be adjusted. However, the operating element can also be designed as a virtual operating element on a display and operating device, for example a touchscreen.

In one embodiment it is provided that the prioritization ratio is specified by the control device depending on an operating situation. This allows the prioritization ratio to be specified depending on the situation. For example, it can be provided to record and/or recognize an operating situation and to determine the prioritization ratio based on the recorded and/or recognized operating situation using a lookup table or a database. The recognition can be done using artificial intelligence and/or machine learning methods. In the lookup table or database, prioritization ratios are assigned to the various operational situations. For example, the following operating situations can be distinguished on a tractor: driving on a country road (traction drive is prioritized over the power take-off), working in the field with activated PTO or hydraulics (power take-off for PTO or hydraulics is prioritized over traction) and working on steep slopes PTO shaft activated (traction drive is prioritized over the power take-off).

In one embodiment it is provided that an actual on-board electrical system direct current is recorded and used as an alternative or in addition to the target on-board electrical system direct current when splitting. This makes it possible to achieve an improved division when controlling the current flow. Particularly in the case in which a target on-board electrical system current is larger or smaller than a real actual on-board electrical system direct current, a current flow can be allocated in an improved manner. In particular, the supply of the on-board electrical system can be ensured in an improved manner. A weighted value can also be formed and used from the actual on-board electrical system direct current and target on-board electrical system direct current.

In one embodiment it is provided that actual direct currents are recorded for the at least two electric drives, with the recorded actual direct currents being used as an alternative or in addition to the target direct currents when dividing. This makes it possible to achieve an improved division when controlling the current flow. In particular, in the case where a (limited) target current is larger or smaller than a real actual direct current, a current flow can be allocated in an improved manner. A deviation can be caused in particular by sample scatter and/or errors in the maps used (interpolation errors, smoothing, etc.). Weighted values can also be formed and used from the actual direct currents and target direct currents.

In one embodiment it is provided that actual direct currents are recorded for the at least two electric drives, with the respective target direct currents of the at least two electric drives limited by the division being regulated based on the respective recorded actual direct currents. The output of the controller is added to the original value of the limited setpoint current. The input of the controller is formed in particular by the control difference from a precontrol value (corresponds to the limited target current value) and the current actual direct current. For example, an I controller can be used as a controller function; In principle, however, other controller functions can also be used. A second input can be provided on the controller, which is designed as a control input and via which an active external torque intervention, in which the amount of the target torque of the drive is reduced, is taken into account.

Further features for the design of the device result from the description of embodiments of the method. The advantages of the device are the same as in the embodiments of the method.

• 1 eine schematische Darstellung einer Ausführungsform der Vorrichtung zum Steuern eines Stromflusses in einem Fahrzeug;
• 2 eine schematische Darstellung zur Verdeutlichung einer Ausführungsform der Vorrichtung und des Verfahrens zum Steuern eines Stromflusses in einem Fahrzeug;
• 3a bis 3d ein schematisches Ablaufdiagramm zur Verdeutlichung einer Implementierung einer Ausführungsform des Verfahrens und der Vorrichtung;
• 4a bis 4c schematische Darstellungen von mittels der Implementierung simulierten zeitlichen Verläufen der Gleichströme zur Verdeutlichung der in den 3a bis 3d gezeigten Ausführungsform;
• 5 eine schematische Darstellung zur Verdeutlichung einer weiteren Ausführungsform der Vorrichtung und des Verfahrens zum Steuern eines Stromflusses in einem Fahrzeug;
• 6 eine schematische Darstellung zur Verdeutlichung einer weiteren Ausführungsform der Vorrichtung und des Verfahrens zum Steuern eines Stromflusses in einem Fahrzeug;
• 7 eine schematische Darstellung von mittels der Implementierung simulierten zeitlichen Verläufen der Gleichströme zur Verdeutlichung der in der 6 gezeigten Ausführungsform.

The invention is explained in more detail below using preferred exemplary embodiments with reference to the figures. Show here:

• 1 a schematic representation of an embodiment of the device for controlling a current flow in a vehicle;
• 2 a schematic representation to illustrate an embodiment of the device and the method for controlling a current flow in a vehicle;
• 3a to 3d a schematic flow diagram to illustrate an implementation of an embodiment of the method and the device;
• 4a to 4c Schematic representations of the time profiles of the direct currents simulated using the implementation to illustrate the in the 3a to 3d embodiment shown;
• 5 a schematic representation to illustrate a further embodiment of the device and the method for controlling a current flow in a vehicle;
• 6 a schematic representation to illustrate a further embodiment of the device and the method for controlling a current flow in a vehicle;
• 7 a schematic representation of the time profiles of the direct currents simulated by means of the implementation to illustrate the in the 6 embodiment shown.

The 1 shows a schematic representation of an embodiment of the device 1 for controlling a current flow in a vehicle 50. The vehicle 50 includes two electric drives 51, 52 and an energy storage 53. The energy storage 53 is in particular a battery. One electric drive 51 is a traction drive, the other electric drive 52 is a power take-off. The two electric drives 51, 52 and an on-board electrical system 54 of the vehicle 50 are powered by the energy storage 53 or feed the energy storage 53.

$$\text{I\_Trac}+\text{I\_Aux}+\text{I\_Con}=\text{I\_Bat}$$

$$\text{P\_Trac}=\text{V\_Bat}*\text{I\_Trac}$$

$$\text{P\_Aux}=\text{V\_Bat}*\text{I\_Aux}$$

$$\text{P\_Con}=\text{V\_Bat}*\text{I\_Con}$$

Current and power flows can be described by the following equations: $$\text{I\_Bat}\in \left[-\text{I\_ChLim},-\text{I\_DisChLim}\right]$$

$$\text{I\_Trac}+\text{I\_Aux}+\text{I\_Con}=\text{I\_Bat}$$

$$\text{P\_Trac}=\text{V\_Bat}*\text{I\_Trac}$$

$$\text{P\_Aux}=\text{V\_Bat}*\text{I\_Aux}$$

$$\text{P\_Con}=\text{V\_Bat}*\text{I\_Con}$$

Here I_Bat is an energy storage direct current. In order to prevent damage to the energy storage 53, in particular the battery, this energy storage direct current I_Bat must not exceed a maximum energy storage direct current I_ChLim, I_DisChLim in terms of amount, depending on the current direction (charging or discharging). I_Trac is the direct current of the electric drive 51 used as a traction drive, I_Aux is the direct current of the electric drive 52 used as a power take-off drive and I_Con is the on-board electrical system current. The respective powers P_Trac, P_Aux and P_Con resulting from the currents I_Trac, I_Aux and I_Con can be derived using the energy storage voltage V_Bat.

• - jeweils ausgehend von einem Solldrehmoment 1.T_Des, 2.T_Des oder einer Solldrehzahl 1.n_Des, 2.n_Des oder Sollphasenströmen (nicht gezeigt, diese sind grundsätzlich über das Kennfeld x.Map1 mit dem Solldrehmoment verknüpft und können entsprechend umgerechnet werden) Sollgleichströme 1.I_DC_Des, 2.I_DC_Des (2) für die zwei Elektroantriebe 51, 52 zu bestimmen, und
• - einen Gleichstromfluss zwischen dem Energiespeicher 53, dem Bordnetz 54 und den zwei Elektroantrieben 51, 52 derart aufzuteilen, dass ein maximaler Betrag eines Energiespeichergleichstroms I_ChLim, I_DisChLim nicht überschritten wird und dass ein Sollbordnetzgleichstrom I_Con_Des (2) mit höchster Priorität bereitgestellt wird, und einen nach Bereitstellen des Sollbordnetzgleichstroms I_Con_Des resultierenden Gleichstrom gemäß einem vorgegebenen Priorisierungsverhältnis AuxPrio auf die zwei Elektroantriebe 51, 52 aufzuteilen und die Sollgleichströme 1.I_DC_Des, 2.I_DC_Des falls erforderlich zu begrenzen.

The device 1 includes a control device 2. The control device 2 includes, for example, a computing device and a memory (both not shown), which carry out the computing operations necessary to carry out the method. The control device 2 is set up to distribute an energy storage direct current I_Bat to the vehicle electrical system 54 and the two electric drives 51, 52, and for this purpose

• - each based on a target torque 1.T_Des, 2.T_Des or a target speed 1.n_Des, 2.n_Des or target phase currents (not shown, these are basically linked to the target torque via the map x.Map1 and can be converted accordingly) target direct currents 1 .I_DC_Des, 2.I_DC_Des ( 2 ) to be determined for the two electric drives 51, 52, and
• - to divide a direct current flow between the energy storage 53, the on-board electrical system 54 and the two electric drives 51, 52 in such a way that a maximum amount of an energy storage direct current I_ChLim, I_DisChLim is not exceeded and that a target on-board electrical system direct current I_Con_Des ( 2 ) is provided with the highest priority, and after providing the target on-board electrical system direct current I_Con_Des, the resulting direct current is divided into the two electric drives 51, 52 according to a predetermined prioritization ratio AuxPrio and the target direct currents 1.I_DC_Des, 2.I_DC_Des are limited if necessary.

It can be provided that the device 1 has a control element 3, with the control element 3 being set up so that the prioritization ratio AuxPrio can be specified by a user. The control element 3 can be, for example, a slider or rotary controller with which the prioritization ratio AuxPrio or a distribution of an available direct current between the two electric drives 51, 52 can be set.

The 2 shows a schematic representation of an embodiment of the device 1 and the method for controlling a current flow in a vehicle. Shown are two signal paths 20, 21 which are in the control device 2 ( 1 ) are passed through. The signal path 20 shown above is that for the electric drive 51 used as a traction drive ( 1 ), the signal path 21 shown below is the one for the electric drive 52 used as a power take-off ( 1 ).

In particular, it is provided that the determination of the target direct currents 1.I_DC_Des, 2.I_DC_Des is based on the respective target torque 1.T_Des, 2.T_Des or the respective target speed 1.n_Des, 2.n_Des using a respective map 1.Map2, 2 .Map2 is done. The map 1.Map2, 2.Map2 forms an actual speed 1.n_Act, 2.n_Act, an energy storage voltage V_Bat and a requested target torque 1.T_Des, 2.T_Des for the respective signal path 20, 21 on a respective target direct current 1.I_DC_Des, 2 .I_DC_Des from. The maps 1.Map2, 2.Map2 are characteristic of the respective electric drives 51, 52 and are in particular determined empirically on a laboratory test stand and/or determined by simulation. It can be provided that the maps 1.Map2, 2.Map2 are temperature-dependent.

The current flow is then divided. This is done in a distribution module 22. This distribution module 22 is assigned the target direct currents 1.I_DC_Des, 2.I_DC_Des, a maximum energy storage direct current I_Bat_Lim (this includes the two values listed above for charging and discharging and can be transferred, for example, as a vector or list), one Target on-board electrical system current I_Con_Des and the prioritization ratio AuxPrio are supplied. According to the procedure, the distribution takes place with the highest priority on the on-board network and then according to the specified prioritization ratio. As a result, the distribution module 22 delivers limited target direct currents 1.I_DC_DesLim, 2.I_DC_DesLim for the two electric drives 51, 52 ( 1 ).

In particular, it is provided that a target direct current 1.I_DC_Des, 2.I_DC_Des determined by means of the respective characteristic map 1.Map2, 2.Map2 is, after dividing, by means of an inverted characteristic map 1.Map2_inv corresponding to the respective characteristic map 1.Map2, 2.Map2, 2.Map2_inv is converted into a limited target torque 1.T_Des_CurrLim, 2.T_Des_CurrLim, based on which the respective electric drive 51, 52 ( 1 ) is regulated. For this purpose, the limited target direct currents 1.I_DC_DesLim, 2.I_DC_DesLim as well as the actual speed 1.n_Act, 2.n_Act and the energy storage voltage V_Bat are supplied to the respective inverted map 1.Map2_inv, 2.Map2_inv. The inverted maps 1.Map2_inv, 2.Map2_inv are or were determined in particular from the maps 1.Map2, 2.Map2.

After determining the limited target torques 1.T_Des_CurrLim, 2.T_Des_CurrLim, a further torque limitation can optionally be provided, with torque limiting modules 23, 24 being provided for this purpose. Here, the limited target torques 1.T_Des_CurrLim, 2.T_Des_CurrLim are further limited based on a torque limit value 1.T_Ext_Lim, 2.T_Ext_Lim set in another way (i.e. independently of the method described in this disclosure) to the limited target torques 1.T_DesLim, 2 .T_DesLim.

The limited target torques 1.T_Des_Lim, 2.T_Des_Lim are then converted into the respective target phase currents 1.I_AC_Des in a manner known per se using maps 1.Map1, 2.Map1, the respective actual speed 1.n_Act, 2.n_Act and the energy storage voltage V_Bat , 2.I_AC_Des converted and used to control the electric drives 51, 52 ( 1 ) used.

The target on-board network current I_Con_Des is made available with the highest priority and a limited value I_Con_Lim is set accordingly to the value I_Con_Des if the conditions for this are met, that is, in particular, the maximum energy storage direct current (I_Bat_Lim) must be sufficient. If the maximum energy storage direct current (I_Bat_Lim) is not sufficient, I_Con_Lim is limited accordingly.

The 3a to 3d show an exemplary implementation of the splitting module 22 ( 2 ), whereby the two electric drives are based on a traction drive (“Trac”) and an auxiliary drive (“Aux”).

In measure 100, the limits are set for motor and generator operation and for the on-board electrical system, whereby it is assumed that I_BatLim := [I_DisChLim, I_ChLim],

In measure 101, the target currents of the electric drives are divided into generator target currents and motor target currents for each electric drive (with 1.I_DC_Des := I_TracDes; 2.I_DC_Des := I_AuxDes).

In measure 102, the balances of the total target direct currents are defined as boundary conditions.

Measure 103 checks whether the total target direct current is within the limits or not. If this is the case, the total target direct current can be provided without a current limitation and the (limiting) values for the target currents for the two electric drives are set accordingly in measure 104. If the total target direct current is not within the limits, a current limitation is necessary and measures 105 are continued.

Measure 105 checks whether the total target direct current is greater than or equal to zero, that is, whether motor operation predominates and discharging is present or whether generator operation predominates and charging is present. If the former is the case, motor operation and discharging are limited (106). If the latter is the case, generator operation and charging are limited (107).

According to measure 106, in 3b proceeded to measure 108. In measure 108 It is checked whether the target direct current I_AuxDes of the power take-off is less than zero in order to check whether discharging is only necessary on the traction drive side. If this is the case, the values for the power take-off are set in measure 109 such that a current generated by the power take-off can be used for charging indefinitely. For the traction drive, the motor target direct current (I_TracMotLim) is set in particular to the limit current, which results from the balance of the discharge current limit (I_MotLim), charging current (I_AuxGenDes) of the auxiliary drive and on-board network current (I_ConDes). However, if this is not the case, a measure 110 checks whether the target direct current I_Trac_Des of the traction drive is less than zero, that is, whether discharging is only necessary on the part of the power take-off. If this is the case, the values for the traction drive are set in measure 111 such that a current generated by the traction drive can be used indefinitely for charging. For the power take-off, the motor target direct current (I_AuxMotLim) is set in particular to the limit current, which results from the balance of the discharge current limit (I_MotLim), charging current of the traction drive (I_TracGenDes) and on-board network current (I_ConDes). However, if this is not the case, the procedure continues with measure 112, which deals with the case in which both electric drives are operated by motors and discharge the energy storage device.

In measure 112, the (motor) target direct currents are divided between the traction drive and the power take-off according to the specified prioritization ratio, which in this example is expressed as the variable AuxPrio with values between 0 and 1.

If there is still direct current (or power) left after taking the prioritized electric drive into account, this is distributed to the less prioritized electric drive.

In measure 113, in the event that any motor direct current limit I_xxxMotLim is less than zero, an on-board power supply direct current limit I_ConLim is reduced and the motor limit values I_xxxMotLim are set to zero.

According to measure 107 ( 3a) is in 3c proceeded to measure 114. Measure 114 checks whether the target direct current I_AuxDes of the power take-off is greater than or equal to zero, that is, whether charging is only necessary on the part of the traction drive. If this is the case, measure 115 ensures that the power take-off is allowed to discharge the entire target current. For the traction drive, the regenerative target direct current (I_TracGenLim) is set in particular to the limit current, which results from the balance between the charging current limit (I_GenLim) and the discharging current (I_AuxMotDes) of the power take-off. However, if this is not the case, measure 116 checks whether charging is only necessary on the power take-off. If this is the case, measure 117 ensures that the traction drive is allowed to discharge the entire target current. For the power take-off, the generator target direct current (I_AuxGenLim) is set to the limit current, which results from the balance between the charging current limit (I_Gen_Lim) and the discharging current (I_TracMotDes) of the traction drive. However, if this is not the case, proceed to measure 118.

In measure 118, the (generative) target direct currents are divided between the traction drive and the power take-off according to the specified prioritization ratio, which in this example is expressed as the variable AuxPrio with values between 0 and 1. If there is still direct current (or power) left after taking the prioritized electric drive into account, this is distributed to the less prioritized electric drive.

As a final measure 119 will be in 3d Total values are formed, that is, the limited target direct currents 1.I_DC_DesLim, 2.I_DC_DesLim, as shown in the 2 are listed, formed and provided.

The 4a , 4b and 4c show simulation results for the with reference to the 3a to 3d example implementation described. Three graphs are shown over time (simulation steps 1 to 120, shown on the x-axis). In all three graphs shown, currents are shown in A, with the different lines corresponding to the quantities designated in the respective legend. The top graph also shows the prioritization ratio in %.

• - I_ConDes = 30 A (ein Bordnetzsollstrom hat einen Wert von 30 A)
• - I_ChLim = -I_DisChLim = 10 A (ein maximaler Ladestrom und ein maximaler Entladestrom des Energiespeichers sind jeweils betragsmäßig 10 A).

The 4a shows the time progression for the following specifications:

• - I_ConDes = 30 A (an on-board network target current has a value of 30 A)
• - I_ChLim = -I_DisChLim = 10 A (a maximum charging current and a maximum discharging current of the energy storage are each 10 A).

For clarity, the prioritization ratio changes over time from 100% to 0% and then back to 60%. The requested target currents I_TracDes and I_AuxDes are each arbitrarily specified and only serve clarifying different situations. Current values above zero indicate motor operation, current values below zero indicate generator operation. Since the on-board network target current I_Con_Des already exceeds the available maximum discharge current I_DisChLim in this example, the electric drives are operated almost exclusively as generators. Motor operation can only take place if one of the electric drives provides enough generator power to fully provide the target electrical system current (see, for example, the power take-off at points 5, 38 and 70, where the traction drive can provide sufficient generator power).

• - I_ConDes = 40 A (ein Bordnetzsollstrom hat einen Wert von 40 A)
• - I_ChLim = -I_DisChLim = 50 A (ein maximaler Ladestrom und ein maximaler Entladestrom des Energiespeichers sind jeweils betragsmäßig 50 A).

The 4b shows the time progression for the following specifications:

• - I_ConDes = 40 A (an on-board network target current has a value of 40 A)
• - I_ChLim = -I_DisChLim = 50 A (a maximum charging current and a maximum discharging current of the energy storage are each 50 A).

• - I_ConDes = 40 A (ein Bordnetzsollstrom hat einen Wert von 40 A)
• - I_ChLim = -I_DisChLim = 80 A (ein maximaler Ladestrom und ein maximaler Entladestrom des Energiespeichers sind jeweils betragsmäßig 80 A).

The 4c shows the time course for the following specifications:

• - I_ConDes = 40 A (an on-board network target current has a value of 40 A)
• - I_ChLim = -I_DisChLim = 80 A (a maximum charging current and a maximum discharging current of the energy storage are each 80 A).

In the 4b and 4c The specifications for the same requested target currents I_TracDes and I_AuxDes of the traction drive and the power take-off are changed. Overall, larger maximum values for the charging and discharging current of the energy storage ensure that motor operation is possible over longer periods of time. In the 4b However, this is much more limited with the power take-off than in the 4c . Clearly visible in 4c is also the effect of the reverse prioritization ratio: There is no motor operation of the traction drive between positions 10 and 15, since the power take-off is fully prioritized (AuxPrio = 100%), whereas motor operation of the traction drive takes place between positions 40 and 50, since there the traction drive is given full priority (AuxPrio = 0%).

The 5 shows a further embodiment of the method and the device. The embodiment is basically like that in 2 Embodiment shown, the same reference numbers designate the same features and terms. In this embodiment it is in contrast to that in the 2 In the embodiment shown, an actual on-board electrical system direct current I_ConAct is recorded and used as an alternative or in addition to the target on-board electrical system direct current when splitting.

It can also be provided that actual direct currents 1.I_DC_Act, 2.I_DC_Act are recorded for the at least two electric drives, with the recorded actual direct currents 1.I_DC_Act, 2.I_DC_Act being used as an alternative or in addition to the target direct currents when splitting.

The 6 shows a further embodiment of the method and the device. In this embodiment it is provided that actual direct currents 1.I_DC_Act, 2.I_DC_Act are recorded for the at least two electric drives, with the respective setpoint direct currents 1.I_DC_DesLim, 2.I_DC_DesLim of the at least two electric drives limited by the division based on the respective recorded actual direct currents 1. I_DC_Act, 2.I_DC_Act are regulated. For this purpose, two controllers 25, 26 are provided (indicated as an I controller, for example). An output of the respective controller 25, 26 is added to the original value x.I_DC_DesLim (pre-control value), which is provided by the distribution module 22. An input of the respective controller 25, 26 is formed by the control difference from the precontrol value (corresponds to the setpoint) x.I_DC_DesLim and the current actual direct current x.I_DC_Act. A controller function can, for example, implement pure I control. In principle, other controller functions can also be used. A second input on the respective controller 25, 26 is in particular a control input x.ExtLimActive, which is necessary if the amount of the target torque x.T_Des of the electric drive is reduced by an active external torque intervention.

The 7 shows simulation results for this embodiment in one 3a to 3d corresponding implementation. Three graphs are shown over time (simulation steps 1 to 120). In all three graphs shown, currents are shown in A, with the different lines corresponding to the quantities designated in the respective legend. The top graph also shows the prioritization ratio in %.

• - I_ConDes = 50 A (ein Bordnetzsollstrom hat einen Wert von 50 A)
• - I_ChLim = -I_DisChLim = 80 A (ein maximaler Ladestrom und ein maximaler Entladestrom des Energiespeichers sind jeweils betragsmäßig 80 A).

The 7 shows the progression for the following specifications, which correspond to the 4c are equivalent to:

• - I_ConDes = 50 A (an on-board network target current has a value of 50 A)
• - I_ChLim = -I_DisChLim = 80 A (a maximum charging current and a maximum discharging current of the The amount of each energy storage device is 80 A).

The 7 additionally shows the incorrect values (I_TracFaulty, I_AuxFaulty) and those using the controllers 25, 26 ( 6 ) regulated values (I_TracCtrl, I_AuxCtrl). It can be clearly seen that the regulated values agree better with the limited target direct currents I_TracLim, I_AuxLim or reach them faster than the incorrect values I_TracFaulty, I_AuxFaulty.

Reference symbol list

1

contraption

2

Control device

3

Control element

20

signaling pathway

21

signaling pathway

22

Splitting module

23

Torque limiting module

24

Torque limiting module

25

Regulator

26

Regulator

50

vehicle

51

Electric drive (traction drive)

52

Electric drive (power take-off)

53

Energy storage (battery)

54

On-board electrical system

100-119

Measures of the procedure

1.I_AC_Des

Target phase currents

1.I_DC_Act

Actual direct current

1.I_DC_Des

Target direct current

1.I_DC_DesLim

limited target direct current

1. ExtLimActive

external torque limitation

1.Map1

Map

1.Map2

Map

1.Map2_inv

inverted map

1.n_Act

Actual speed

1.n_Des

Target speed

1.T_Des

Target torque

1.T_Des_CurrLim

limited target torque

1.T_Ext_Lim

Torque limit

2.I_AC_Des

Target phase currents

2.I_DC_Act

Actual direct current

2.I_DC_Des

Target direct current

2.I_DC_DesLim

limited target direct current

2.ExtLimActive

external torque limitation

2.Map1

Map

2.Map2

Map

2.Map2_inv

inverted map

2.n_Act

Actual speed

2.n_Des

Target speed

2.T_Des

Target torque

2.T_Des_CurrLim

limited target torque

2.T_Ext_Lim

Torque limit

AuxPrio

Prioritization ratio

I_Aux

Direct current (power take-off)

I_AuxCtrl

regulated value (power take-off)

I_AuxDes

Target direct current (power take-off)

I_AuxFaulty

incorrect value (power take-off)

I_Bat

Direct current energy storage

I_Bat_Lim

maximum energy storage direct current

I_ChLim

maximum charging current

I_Con_Act

Actual on-board power supply

I_Con_Des

Target on-board network current

I_DisChLim

maximum discharge current

I_Trac

Direct current (traction drive)

I_TracCtrl

regulated value (traction drive)

I_TracDes

Target direct current (traction drive)

I_TracFaulty

incorrect value (traction drive)

P_Aux

Power (power take-off)

P_Con

Performance (on-board network)

P_Trac

Power (power take-off)

V_Bat

Energy storage voltage (battery voltage)

Claims (10)

Method for controlling a current flow in a vehicle (50), the vehicle (50) having at least two electric drives (51, 52) and an energy storage device (53), wherein the at least two electric drives (51, 52) and an on-board electrical system (54) are fed by means of the energy storage (53) or feed the energy storage (53), wherein an energy storage direct current (I_Bat) is distributed between the vehicle electrical system (54) and the at least two electric drives (51, 52), whereby this - in each case starting from a target torque (x.T_Des) or a target speed (x.n_Des) or target phase currents, target direct currents (x.I_DC_Des) are determined for the at least two electric drives (51, 52), and - A direct current flow between the energy storage (53), the on-board electrical system (54) and the at least two electric drives (51, 52) is divided in such a way that a maximum amount of an energy storage direct current (I_Bat_Lim) is not exceeded and that a target on-board electrical system direct current (I_Con_Des) with the highest Priority is provided, wherein a direct current resulting after provision of the target on-board electrical system direct current (I_Con_Des) is divided between the at least two electric drives (51, 52) according to a predetermined prioritization ratio (AuxPrio) and the target direct currents (x.I_DC_Des) are limited if necessary. Procedure according to Claim 1 , characterized in that the target direct currents (x.I_DC_Des) are determined based on the target torque (x.T_Des) or the target speed (x.n_Des) or the target phase currents using at least one map (x.Map2). Procedure according to Claim 2 , characterized in that a target direct current (x.I_DC_Des) determined by means of the at least one map (x.Map2) is divided into a target torque (x.T_Des-CurrLim ) is converted, based on which the respective electric drive (51,52) is regulated. Method according to one of the preceding claims, characterized in that the prioritization ratio (AuxPrio) is or can be specified by a user of the vehicle (50) using a control element (3) set up for this purpose. Method according to one of the preceding claims, characterized in that an actual on-board electrical system direct current (I_Con_Act) is recorded and used when dividing as an alternative or in addition to the target on-board electrical system direct current (I_Con_Des). Method according to one of the preceding claims, characterized in that actual direct currents (x.I_DC_Act) are recorded for the at least two electric drives (51, 52), the recorded actual direct currents (x. I_DC_Act) can be used. Method according to one of the preceding claims, characterized in that actual direct currents (x.I_DC_Act) for the at least two electric drives (51, 52) are recorded, the respective target direct currents (x.I_DC_DesLim) of the at least two electric drives (51, 51) being limited by the division. 52) can be regulated based on the respective recorded actual direct currents (x.I_DC_Act). Device (1) for controlling a current flow in a vehicle (50), the vehicle (50) having at least two electric drives (51,52) and an energy storage (53), the at least two electric drives (51,52) and an on-board electrical system (54) are fed by means of the energy storage (53) or feed the energy storage (53), comprising: a control device (2), the control device (2) being set up to supply a direct energy storage current (I_Bat) to the vehicle electrical system (54) and the to divide at least two electric drives (51,52), and for this purpose - each based on a target torque (x.T_Des) or a target speed (x.n_Des) or target phase currents, target direct currents (x.I_DC_Des) for the at least two electric drives (51,52). determine, and - divide a direct current flow between the energy storage (53), the on-board electrical system (54) and the at least two electric drives (51, 52) in such a way that a maximum amount of an energy storage direct current (I_Bat_Lim) is not exceeded and that a target on-board electrical system direct current (I_Con_Des) is provided with the highest priority, and to divide a direct current resulting after provision of the target on-board electrical system direct current (I_Con_Des) between the at least two electric drives (51, 52) according to a predetermined prioritization ratio (AuxPrio) and to limit the target direct currents (x.I_DC_Des) if necessary. Device (1) according to Claim 8 , characterized by a control element (3), the control element (3) being set up so that the prioritization ratio (AuxPrio) can be specified by a user. Vehicle (50), comprising at least one device (1). Claim 8 or 9 .

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