Method and device for controlling an electric current flow in a vehicle

Abstract

Method for controlling the flow of electricity in a vehicle (50), wherein the vehicle (50) has two electric drives (51, 52) and an energy storage device (53), wherein one electric drive (51) is a traction drive and the other electric drive (52) is an auxiliary drive for a power take-off shaft or a hydraulic system, wherein the two electric drives (51, 52) and an on-board electrical system (54) are powered by the energy storage device (53) or power the energy storage device (53), where an energy storage direct current (I_Bat) is divided between the on-board network (54) and the two electric drives (51,52), where this - starting from a target torque (x.T_Des) or a target speed (x.n_Des) or target phase currents, target DC currents (x.I_DC_Des) for the two electric drives (51,52) are determined, and - a direct current flow between the energy storage device (53), the vehicle electrical system (54) and the two electric drives (51, 52) is distributed such that a maximum amount of energy storage direct current (I_Bat_Lim) is not exceeded and that a target vehicle electrical system direct current (I_Con_Des) is provided with the highest priority, wherein a direct current resulting after provision of the target vehicle electrical system direct current (I_Con_Des) is distributed to the two electric drives (51, 52) according to a predefined prioritization ratio (AuxPrio) and the target direct currents (x.I_DC_Des) are limited if necessary, wherein the prioritization ratio (AuxPrio) is or can be specified by a user of the vehicle (50) by means of a control element (3) provided for this purpose, or where the prioritization ratio (AuxPrio) is predetermined depending on an operational situation.

Description

[0001] The invention relates to a method and a device for controlling an electric current flow in a vehicle.

[0002] As electrification progresses in the transport sector, commercial vehicles, such as agricultural machinery, are increasingly being electrified. A particular challenge here is that, in addition to the main drive, an auxiliary drive may also be present, which, for example, powers a power take-off (PTO) shaft or hydraulics. In this case, it is especially important to consider the power or current limitations of the vehicle's high-voltage battery.

[0003] From EP 2 782 805 B1, a method for controlling the operation of an arrangement of at least two electric machines, which are motion-coupled to different wheels of a motor vehicle and connected to a battery, is known, wherein the battery provides a current minimum and a current maximum limiting current for the electric machines, wherein target torques for the electric machines are provided by a drive control logic, wherein a target current resulting from the target torque is determined for each electric machine, and the sum of the target currents of the electric machines is compared with the maximum and minimum limiting currents, wherein if the sum lies outside the interval defined by the limiting currents, the target currents are modified by means of at least one change rule so that the sum of the target currents lies within the limiting currents, and modified target torques are determined from the modified target currents.which are used to control the electric machines.

[0004] From DE 10 2013 013 953 A1, a method for controlling a drive device of an at least partially electrically driven vehicle comprising at least two vehicle wheels mechanically coupled by means of an electric drive unit each, is known, wherein the electric drive units each obtain electrical energy from an electrical energy storage device in motor operation and / or supply electrical energy to the electrical energy storage device in generator operation, wherein the electric drive units provide a torque in the intended operation according to a drive unit-specific torque specification of a vehicle control system, wherein a maximum total torque is determined taking into account a maximum available power of the electrical energy storage device and a sum formed from the drive unit-specific torque specifications is limited by means of the maximum total torque.

[0005] From DE 10 2020 205 059 A1, a method for controlling an electrical machine is known, comprising the steps: determining a target switching angle; determining a target state; determining an actual state; determining a difference between the target state and the actual state; determining a switching angle adjustment using a controller as a function of the difference; controlling the electrical machine using the sum of the target switching angle and the switching angle adjustment.

[0006] From EP 2 788 234 B1, a method for improving the availability of an electromechanical actuator of an electromechanical or electrohydraulic braking system in a motor vehicle is known, comprising a motor controller for an electric motor, wherein the motor controller operates in an unrestricted operating mode. In addition to the unrestricted operating mode, further operating modes for the motor controller are defined, wherein these further operating modes operate with restricted access to state variables of the electric motor and the electronic control of the electric motor, and in these further operating modes, depending on the restricted access, a change in the control method and / or a deactivation of individual functions of the motor controller is carried out. Furthermore, an electronic device for use with an electromechanical or electrohydraulic braking system is known.

[0007] The invention is based on the objective of creating a method and a device for controlling a current flow in a vehicle.

[0008] The problem is solved according to the invention by a method with the features of claim 1 and a device with the features of claim 7. Advantageous embodiments of the invention are set forth in the dependent claims.

[0009] In particular, a method for controlling a current flow in a vehicle is provided, wherein the vehicle has two electric drives and an energy storage device, wherein the two electric drives and an on-board electrical system are supplied by means of the energy storage device or supply the energy storage device, wherein an energy storage direct current is distributed between the on-board electrical system and the two electric drives, wherein for this purpose - starting from a target torque or target speed or target phase currents, target DC currents are determined for the two electric drives, and - a direct current flow between the energy storage, the vehicle electrical system and the two electric drives is divided in such a way that a maximum amount of energy storage direct current is not exceeded and that a target vehicle electrical system direct current is provided with the highest priority, whereby a direct current resulting after provision of the target vehicle electrical system direct current is divided between the two electric drives according to a predetermined prioritization ratio and the target direct currents are limited if necessary.

[0010] Furthermore, in particular a device for controlling a current flow in a vehicle is provided, wherein the vehicle has two electric drives and an energy storage device, wherein the two electric drives and an on-board electrical system are supplied by means of the energy storage device or supply the energy storage device, comprising a control device, wherein the control device is configured to distribute an energy storage direct current to the on-board electrical system and the two electric drives, and for this purpose - to determine target DC currents for the two electric drives, starting from a target torque or target speed or target phase currents, and - to divide a direct current flow between the energy storage, the vehicle electrical system and the two electric drives in such a way that a maximum amount of energy storage direct current is not exceeded and that a target vehicle electrical system direct current is provided with the highest priority, and to divide any direct current resulting after provision of the target vehicle electrical system direct current between the two electric drives according to a predetermined prioritization ratio and to limit the target direct currents if necessary.

[0011] The method and device make it possible to ensure that the limited power or current with which the energy storage device can be discharged or charged is not exceeded and that the available power or current is distributed accordingly between the vehicle electrical system and two electric drives. This is done based on a target vehicle electrical system current and target DC currents, which are determined for the two electric drives based on a respective target torque, target speed, or target phase currents (especially in the form of target phase current vectors; some motor controllers provide target phase currents / current vectors). The vehicle electrical system is supplied with the highest priority first, as it typically powers important and essential control and / or monitoring equipment.The resulting direct current (DC) after subtracting the target on-board current is then distributed between the two electric drives according to a predefined prioritization ratio. If the resulting DC is sufficient for both electric drives, both target DC currents are provided in full. If, however, the resulting DC is insufficient, it is allocated according to the predefined prioritization ratio. For this purpose, the target DC currents are limited if necessary. As a consequence of such a limitation, the affected electric drive is then operated only with the limited target DC current (or not at all), and / or the limited target DC current is used to determine a (limited) target torque, a (limited) target speed, or (limited) target phase currents, from which the electric drive is controlled.It is noted that even when using speed control, ultimately a target torque and / or target phase currents are derived from the speed controller (cascade control).

[0012] The method and the device control the current flow, particularly independently of the operating mode of the two electric drives. The current flow can be split for both motor and generator operation. For this purpose, the direct currents are specifically considered with a corresponding sign, which indicates the direction of the power or current flow.

[0013] Two electric drives are planned. One is a traction drive, and the other is an auxiliary drive for a power take-off (PTO) or hydraulics. The two electric drives have a nominal power output of approximately the same amount. However, the nominal power outputs can also be different.

[0014] The vehicle is specifically a commercial vehicle, such as a tractor or other agricultural machinery. However, it can also be any other land, rail, water, air, or space vehicle, such as an air taxi or a drone.

[0015] The prioritization ratio includes, in particular, a setting that prioritizes the two electric drives. For two electric drives, the prioritization ratio can be specified as a value between 0 and 1 or a value between 0 and 100 (e.g., as a percentage). At the extreme values ​​of 0 and 1 or 0 and 100, one of the two electric drives is fully prioritized (e.g., 0 = first electric drive; 1 = second electric drive). This means that if the resulting DC current is insufficient for both target DC currents, the prioritized electric drive is supplied first, and only when its target DC current can be fully supplied is the remaining portion of the resulting DC current supplied to the other electric drive. At a value of 0.5, the resulting DC current is divided equally between both electric drives.For more than two electric drives, the prioritization ratio is determined accordingly, establishing a prioritization order and a specific ratio. For example, the first electric drive can be supplied with the highest priority, followed by the second, then the third, and so on. Alternatively, the first electric drive can be supplied with the highest priority, but the remaining DC power is then split 50:50 between the second and third electric drives.

[0016] Parts of the device, in particular the control unit, can be designed individually or collectively as a combination of hardware and software, for example as program code that runs on a microcontroller or microprocessor. However, it is also possible for parts to be designed individually or collectively as an application-specific integrated circuit (ASIC) and / or a field-programmable gate array (FPGA).

[0017] An alternative approach envisages that the prioritization ratio be set, or can be set, by the vehicle user via a dedicated control element. This allows the vehicle user to specify which electric drive should be given priority. In the case of two electric drives, the control element could be a slider or rotary knob for adjusting the prioritization ratio. Alternatively, the control element could be a virtual control on a display and control device, such as a touchscreen.

[0018] Another alternative approach proposes that the prioritization ratio be determined by the control unit based on the operating situation. This allows the prioritization ratio to be predefined depending on the situation. For example, it could be possible to detect and / or recognize an operating situation and, based on this detected and / or recognized situation, determine the prioritization ratio using a lookup table or database. This recognition could be achieved using artificial intelligence and / or machine learning methods. Prioritization ratios would then be assigned to the various operating situations in the lookup table or database.For example, the following operating situations can be distinguished for a tractor: driving on a country road (traction drive is prioritized over the auxiliary drive), working in the field with the PTO or hydraulics activated (auxiliary drive for the PTO or hydraulics is prioritized over the traction drive) and working on a steep slope with the PTO activated (traction drive is prioritized over the auxiliary drive).

[0019] In one embodiment, the target DC currents are determined based on the target torque, target speed, or target phase currents using at least one characteristic map. This allows for a particularly simple and computationally efficient determination of the target DC current. 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 DC current. The at least one characteristic map can also be expressed as a mathematical function, for example, using a polynomial function. The characteristic maps are determined, in particular, through empirical test series 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.

[0020] 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 division by means of an inverted characteristic map corresponding to the at least one characteristic map, from which the respective electric drive is controlled.

[0021] In one embodiment, the actual on-board DC current is detected and used as an alternative or supplement to the target on-board DC current during distribution. This allows for improved distribution when controlling the current flow. In particular, when a target on-board current is higher or lower than the actual on-board DC current, the current flow can be allocated more effectively. Specifically, the supply to the on-board electrical system can be better ensured. A weighted value can also be calculated and used based on the actual on-board DC current and the target on-board DC current.

[0022] In one embodiment, the actual DC currents for the two electric drives are measured, and these measured currents are used as an alternative or supplement to the target DC currents when distributing the current. This allows for improved distribution when controlling the current flow. In particular, if a (limited) target current is larger or smaller than the actual DC current, the current flow can be allocated more effectively. Such deviations can be caused by variations between individual units and / or errors in the characteristic curves used (interpolation errors, smoothing, etc.). Weighted values ​​can also be calculated and used from the actual DC currents and the target DC currents.

[0023] In one embodiment, the actual DC currents for the two electric drives are measured, and the respective target DC currents of the two electric drives, limited by the power distribution, are controlled based on the measured actual DC currents. The controller output is added to the original value of the limited target current. The controller input is formed, in particular, by the control error resulting from a feedforward value (corresponding to the limited target current value) and the current actual DC current. An integral (I) controller can be used as the controller function; however, other controller functions can also be used. A second input can be provided on the controller, configured as a control input, which takes into account an active external torque intervention that reduces the magnitude of the drive's target torque.

[0024] Further features relating to the design of the device are described in the description of embodiments of the method. The advantages of the device are the same in each case as in the embodiments of the method.

[0025] The invention is explained in more detail below with reference to preferred embodiments and the figures. These show: Fig. 1 a schematic representation of an embodiment of the device for controlling a current flow in a vehicle; Fig. 2 a schematic representation to illustrate an embodiment of the device and method for controlling a current flow in a vehicle; Fig. 3a to 3d a schematic flowchart to illustrate an implementation of an embodiment of the method and the device; Fig. 4a to 4c schematic representations of time courses of the direct currents simulated by means of the implementation to illustrate the in the Fig. embodiment shown in 3a to 3d; Fig. 5 a schematic representation to illustrate a further embodiment of the device and method for controlling a current flow in a vehicle; Fig. 6 a schematic representation to illustrate a further embodiment of the device and method for controlling a current flow in a vehicle; Fig. 7. A schematic representation of the time courses of the direct currents simulated by means of the implementation to illustrate the in the Fig. 6 shown embodiment.

[0026] The Fig. Figure 1 shows a schematic representation of an embodiment of the device 1 for controlling a current flow in a vehicle 50. The vehicle 50 comprises two electric drives 51, 52 and an energy storage device 53. The energy storage device 53 is, in particular, a battery. One electric drive 51 is a traction drive, the other electric drive 52 is an auxiliary drive. The two electric drives 51, 52 and an on-board electrical system 54 of the vehicle 50 are powered by the energy storage device 53 or power the energy storage device 53.

[0027] Current and power flows can be described by the following equations: I_Bat ε[−I_ChLim,−I_DisChLim] I_Trac+I_Aux+I_Con=I_Bat P_Trac=V_Bat*I_Trac P_Aux=V_Bat*I_Aux P_Con=V_Bat*I_Con

[0028] Here, I_Bat is a direct current for energy storage. To prevent damage to the energy storage device 53, particularly the battery, this direct current I_Bat must not exceed a maximum direct current I_ChLim, I_DisChLim, 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 an auxiliary drive, and I_Con is the vehicle 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.

[0029] The device 1 comprises a control unit 2. The control unit 2 includes, for example, a computing unit and a memory (both not shown), which perform the necessary calculations for carrying out the method. The control unit 2 is configured to distribute a direct current energy storage current I_Bat to the vehicle electrical system 54 and the two electric drives 51, 52, and for this purpose - each starting from 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 characteristic map x.Map1 and can be converted accordingly) Target DC currents 1.I_DC_Des, 2.I_DC_Des ( Fig. 2) to determine for the two electric drives 51, 52, and - to distribute a direct current flow between the energy storage device 53, the vehicle electrical system 54 and the two electric drives 51, 52 in such a way that a maximum value of an energy storage direct current I_ChLim, I_DisChLim is not exceeded and that a target vehicle electrical system direct current I_Con_Des ( Fig. 2) is provided with the highest priority, and to divide the resulting DC current after provision of the target on-board DC current I_Con_Des according to a predetermined prioritization ratio AuxPrio between the two electric drives 51, 52 and to limit the target DC currents 1.I_DC_Des, 2.I_DC_Des if necessary.

[0030] The device 1 may be provided with a control element 3, wherein the control element 3 is configured so that the prioritization ratio AuxPrio can be set by a user. The control element 3 can, for example, be a slider or rotary control with which the prioritization ratio AuxPrio or a distribution of an available DC current between the two electric drives 51, 52 can be set.

[0031] The Fig. Figure 2 shows a schematic representation of an embodiment of the device 1 and the method for controlling a current flow in a vehicle. Two signal paths 20, 21 are shown which are located in the control unit 2 ( Fig. 1) are traversed. The signal path 20 shown above is the one for the electric drive 51 used as a traction drive ( Fig. 1), the signal path 21 shown below is the one for the electric drive 52 used as an auxiliary drive ( Fig. 1).

[0032] It is specifically intended that the determination of the target DC currents 1.I_DC_Des, 2.I_DC_Des is carried out 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 characteristic map 1.Map2, 2.Map2. The characteristic map 1.Map2, 2.Map2 maps 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 to a respective target DC current 1.I_DC_Des, 2.I_DC_Des for the respective signal path 20, 21. The characteristic maps 1.Map2 and 2.Map2 are characteristic of the respective electric drives 51 and 52 and are determined empirically on a laboratory test bench and / or by simulation. It may be possible for the characteristic maps 1.Map2 and 2.Map2 to be temperature-dependent.

[0033] The current flow is then divided. This takes place in a division module 22. The target DC currents 1.I_DC_Des, 2.I_DC_Des, a maximum energy storage DC current I_Bat_Lim (this comprises the two previously listed values ​​for charging and discharging and can be passed, for example, as a vector or list), a target on-board network current I_Con_Des, and the prioritization ratio AuxPrio are supplied to this division module 22. The division is performed according to the procedure, first with the highest priority to the on-board network and then according to the specified prioritization ratio. As a result, the division module 22 delivers limited target DC currents 1.I_DC_DesLim, 2.I_DC_DesLim for the two electric drives 51, 52 ( Fig. 1).

[0034] It is specifically 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 converted, after division by means of an inverted characteristic map 1.Map2_inv, 2.Map2_inv corresponding to the respective characteristic map 1.Map2, 2.Map2, into a limited target torque 1.T_Des_CurrLim, 2.T_Des_CurrLim, starting from which the respective electric drive 51, 52 ( Fig. 1) is regulated. For this purpose, the limited target DC 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 characteristic maps 1.Map2_inv, 2.Map2_inv. The inverted characteristic maps 1.Map2_inv, 2.Map2_inv are or were determined in particular from the characteristic maps 1.Map2, 2.Map2.

[0035] After determining the limited target torques 1.T_Des_CurrLim, 2.T_Des_CurrLim, a further torque limitation can optionally be provided, for which torque limitation modules 23, 24 are provided. In this case, the limited target torques 1.T_Des_CurrLim, 2.T_Des_CurrLim are further limited from a torque limit value 1.T_Ext_Lim, 2.T_Ext_Lim set by other means (i.e., independently of the method described in this disclosure) to the limited target torques 1.T_DesLim, 2.T_DesLim.

[0036] The limited target torques 1.T_Des_Lim, 2.T_Des_Lim are subsequently converted into the respective target phase currents 1.I_AC_Des, 2.I_AC_Des in a manner known per se using characteristic maps 1.Map1, 2.Map1, the respective actual speed 1.n_Act, 2.n_Act and the energy storage voltage V_Bat in a manner known per se and used to control the electric drives 51, 52 ( Fig. 1) used.

[0037] The target on-board current I_Con_Des is provided with the highest priority, and a corresponding limited value, I_Con_Lim, is set to the value I_Con_Des when the conditions for this are met; that is, in particular, the maximum energy storage DC current (I_Bat_Lim) must be sufficient. If the maximum energy storage DC current (I_Bat_Lim) is insufficient, I_Con_Lim is limited accordingly.

[0038] The Fig. Figures 3a to 3d show an exemplary implementation of the partitioning module 22 ( Fig. 2), where the two electric drives are assumed to be a traction drive (“Trac”) and an auxiliary drive (“Aux”).

[0039] In measure 100, the limits for motor and generator operation and for the on-board network are set, assuming that I_BatLim := [I_DisChLim, I_ChLim].

[0040] 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).

[0041] In measure 102, the balances of the total target flow rates are defined as boundary conditions.

[0042] In step 103, it is checked whether the total target DC current is within the limits. If so, the total target DC current can be provided without current limiting, and the (limiting) values ​​for the target currents for the two electric drives are set accordingly in step 104. If the total target DC current is not within the limits, current limiting is necessary, and the process continues with step 105.

[0043] Measure 105 checks whether the total target direct current is greater than or equal to zero, that is, whether motor operation predominates and discharge is occurring, or whether generator operation predominates and charging is occurring. If the former is the case, motor operation and discharge are limited (106). If the latter is the case, generator operation and charging are limited (107).

[0044] According to measure 106, in Fig. 3b continued with measure 108. In measure 108, it is checked whether the target DC current I_AuxDes of the auxiliary drive is less than zero, in order to verify whether discharge is only necessary on the part of the traction drive. If this is the case, the values ​​for the auxiliary drive are set in measure 109 such that the current generated by the auxiliary drive can be used for charging without limit. For the traction drive, the motor's target DC current (I_TracMotLim) is specifically set to the limit current, which results from the balance of the discharge current limit (I_MotLim), the charging current (I_AuxGenDes) of the auxiliary drive, and the vehicle electrical system current (I_ConDes). If, however, this is not the case, measure 110 checks whether the target DC current I_Trac_Des of the traction drive is less than zero, i.e., whether discharge is only necessary on the part of the auxiliary drive.If this is the case, the values ​​for the traction drive in step 111 are set such that the current generated by the traction drive can be used for charging without limit. For the auxiliary drive, the target DC current for the motor (I_AuxMotLim) is specifically set to the limit current, which results from the balance of the discharge current limit (I_MotLim), the charging current of the traction drive (I_TracGenDes), and the vehicle electrical system current (I_ConDes). If, however, this is not the case, step 112 is used, which addresses the case in which both electric drives are operated as motors and discharge the energy storage system.

[0045] In measure 112, the (motor) target DC currents are distributed between the traction drive and the auxiliary drive according to the specified prioritization ratio, which in this example is expressed as the variable AuxPrio with values ​​between 0 and 1. If any DC current (or power) remains after considering the prioritized electric drive, it is distributed to the less prioritized electric drive.

[0046] In measure 113, if any motor DC current limit I_xxxMotLim is less than zero, a system DC current limit I_ConLim is reduced and the motor limit values ​​I_xxxMotLim are set to zero.

[0047] According to measure 107 ( Fig. 3a) will be in Fig. 3c continued with measure 114. Measure 114 checks whether the target DC current I_AuxDes of the auxiliary drive is greater than or equal to zero, i.e., whether charging is only necessary from the traction drive. If this is the case, measure 115 ensures that the auxiliary drive is allowed to discharge the entire target current. For the traction drive, the generator target DC current (I_TracGenLim) is set to the limit current, which results from the balance between the charging current limit (I_GenLim) and the discharge current (I_AuxMotDes) of the auxiliary drive. If, however, this is not the case, measure 116 checks whether charging is only necessary from the auxiliary drive. If this is the case, measure 117 ensures that the traction drive is allowed to discharge the entire target current.For the auxiliary drive, the regenerative DC target 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. If this is not the case, action 118 is continued.

[0048] In measure 118, the (generative) target DC currents are distributed between the traction drive and the auxiliary drive according to the specified prioritization ratio, which in this example is expressed as the variable AuxPrio with values ​​between 0 and 1. If any DC current (or power) remains after considering the prioritized electric drive, it is distributed to the less prioritized electric drive.

[0049] As a last measure, 119 will be in Fig. 3D sum values ​​are formed, that is, the limited target DC currents 1.I_DC_DesLim, 2.I_DC_DesLim are calculated, as shown in the Fig. 2 are listed, formed and provided.

[0050] The Fig. 4a, Fig. 4b and Fig. 4c show simulation results for the with reference to the Fig. Figures 3a to 3d describe an exemplary implementation. Three graphs are shown over time (simulation steps 1 to 120, represented on the x-axis). In each of the three graphs, flows are represented in A, with the different lines corresponding to the quantities labeled in the respective legend. The top graph in each figure also shows the prioritization ratio in %.

[0051] The Fig. 4a shows the timeline for the following requirements: - I_ConDes = 30 A (a standard on-board current has a value of 30 A) - I_ChLim = -I_DisChLim = 10 A (the maximum charging current and the maximum discharging current of the energy storage device are each 10 A in magnitude).

[0052] The prioritization ratio is changed over time from 100% to 0% and then back to 60% for illustrative purposes. The respective requested target currents I_TracDes and I_AuxDes are arbitrarily defined and serve only to clarify different situations. Current values ​​above zero indicate motor operation, current values ​​below zero indicate generator operation. Since the on-board power supply 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. Only if one of the electric drives provides enough power as a generator to fully supply the on-board power supply target current can motor operation also occur (see, for example, the auxiliary drive at points 5, 38, and 70, where the traction drive can provide sufficient current as a generator).

[0053] The Fig. 4b shows the timeline for the following requirements: - I_ConDes = 40 A (a standard on-board current has a value of 40 A) - I_ChLim = -I_DisChLim = 50 A (the maximum charging current and the maximum discharging current of the energy storage device are each 50 A in magnitude).

[0054] The Fig. Figure 4c shows the timeline for the following specifications: - I_ConDes = 40 A (a standard on-board current has a value of 40 A) - I_ChLim = -I_DisChLim = 80 A (the maximum charging current and the maximum discharging current of the energy storage device are each 80 A in magnitude).

[0055] In the Fig. 4b and Fig. In section 4c, the specifications for the same requested target currents I_TracDes and I_AuxDes of the traction drive and the auxiliary drive have been changed. Overall, larger maximum values ​​for the charging and discharging current of the energy storage system ensure that motor operation is possible for longer periods. Fig. 4b, however, this is much more restricted in the case of the auxiliary drive than in the Fig. 4c. Clearly recognizable in Fig. 4c is also the effect of the reverse prioritization ratio: Thus, there is no motor operation of the traction drive between positions 10 and 15, since the auxiliary drive is fully prioritized (AuxPrio = 100%), whereas motor operation of the traction drive occurs between positions 40 and 50, since the traction drive is fully prioritized there (AuxPrio = 0%).

[0056] The Fig. Figure 5 shows a further embodiment of the method and the device. This embodiment is fundamentally the same as that shown in Figure 5. Fig. 2. In the embodiment shown, the same reference numerals denote the same features and terms. In this embodiment, unlike the one shown in the Fig. In the embodiment shown in section 2, it is provided that an actual on-board DC current I_ConAct is detected and used as an alternative or supplement to the target on-board DC current when splitting.

[0057] It may also be provided that actual DC currents 1.I_DC_Act, 2.I_DC_Act are recorded for the two electric drives, whereby the recorded actual DC currents 1.I_DC_Act, 2.I_DC_Act are used as an alternative or supplement to the target DC currents when splitting.

[0058] The Fig. Figure 6 shows a further embodiment of the method and the device. In this embodiment, actual DC currents 1.I_DC_Act, 2.I_DC_Act for the two electric drives are detected, and the respective target DC currents 1.I_DC_DesLim, 2.I_DC_DesLim of the two electric drives, limited by the splitting, are controlled based on the respective detected actual DC currents 1.I_DC_Act, 2.I_DC_Act. For this purpose, two controllers 25, 26 are provided (indicated by way of example as I-controllers). An output of each controller 25, 26 is added to the original value x.I_DC_DesLim (feedback value) provided by the splitting module 22. An input of the respective controller 25, 26 is formed by the control deviation of the feedforward value (corresponding to the setpoint) x.I_DC_DesLim and the current actual DC 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 each controller 25, 26 is, in particular, a control input x.ExtLimActive, which is necessary if the magnitude of the target torque x.T_Des of the electric drive is reduced by an active external torque intervention.

[0059] The Fig. Figure 7 shows simulation results for this embodiment in a the Fig. 3a to 3d corresponding implementation. Three graphs are shown over time (simulation steps 1 to 120). In all three graphs, flows in A are represented, with the different lines corresponding to the quantities labeled in the respective legend. The upper graph also shows the prioritization ratio in %.

[0060] The Fig. Figure 7 shows the process for the following specifications, which are those of the Fig. 4c correspond to: - I_ConDes = 50 A (a standard on-board current has a value of 50 A) - I_ChLim = -I_DisChLim = 80 A (the maximum charging current and the maximum discharging current of the energy storage device are each 80 A in magnitude).

[0061] The Fig. Figure 7 also shows the faulty values ​​(I_TracFaulty, I_AuxFaulty) and those controlled by controllers 25 and 26 ( Fig. 6) regulated values ​​(I_TracCtrl, I_AuxCtrl). It is clearly evident that the regulated values ​​correspond better to the limited target DC currents I_TracLim, I_AuxLim, or reach them faster, than the faulty values ​​I_TracFaulty, I_AuxFaulty. Reference symbol list 1 Device 2 Control unit 3 Control element 20 Signal path 21 Signal path 22 Division module 23 Torque Limiting Module 24 Torque Limiting Module 25 regulators 26 regulators 50 vehicles 51 Electric drive (traction drive) 52 Electric drive (auxiliary drive) 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 Set Direct Current 1.I_DC_DesLim limited target DC current 1.ExtLimActive external torque limiter 1.Map1 Characteristic field 1.Map2 characteristic curve 1.Map2_inv inverted map 1.n_Act Actual Speed 1.n_Des target speed 1.T_Des Zieldrehtorque 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 Set Direct Current 2.I_DC_DesLim limited target DC current 2.ExtLimActive external torque limiter 2.Map1 Characteristic field 2.Map2 characteristic curve 2.Map2_inv inverted map 2.n_Act Actual Speed 2.n_Des target speed 2.T_Des Zieldrehtorque 2.T_Des_CurrLim limited target torque 2.T_Ext_Lim Torque Limit AuxPrio prioritization ratio I_Aux DC (Auxiliary drive) I_AuxCtrl controlled value (auxiliary drive) I_AuxDes Direct Current (Auxiliary Drive) I_AuxFaulty faulty value (auxiliary drive) I_Bat Energy storage direct current I_Bat_Lim maximum energy storage direct current I_ChLim maximum charging current I_Con_Act Current on-board power I_Con_Des Sollbordnetzstrom I_DisChLim maximum discharge current I_Trac DC (traction drive) I_TracCtrl controlled value (traction drive) I_TracDes Direct current (traction drive) I_TracFaulty faulty value (traction drive) P_Aux power (auxiliary drive) P_Con power (on-board electrical system) P_Trac power (auxiliary drive) V_Bat Energy storage voltage (battery voltage)

Claims

Method for controlling a current flow in a vehicle (50), wherein the vehicle (50) has two electric drives (51, 52) and an energy storage device (53), wherein one electric drive (51) is a traction drive and the other electric drive (52) is an auxiliary drive for a power take-off shaft or a hydraulic system, wherein the two electric drives (51, 52) and an on-board electrical system (54) are supplied by means of the energy storage device (53) or supply the energy storage device (53), wherein an energy storage direct current (I_Bat) is distributed to the on-board electrical system (54) and the two electric drives (51, 52), wherein, for this purpose, 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) for the two electric drives (51, 52) are determined, and a direct current flow between the energy storage device (53), the vehicle electrical system (54) and the two electric drives (51, 52) is distributed such that a maximum amount of an energy storage direct current (I_Bat_Lim) is not exceeded and that a target vehicle electrical system direct current (I_Con_Des) is provided with the highest priority, wherein a direct current resulting after provision of the target vehicle electrical system direct current (I_Con_Des) is distributed to the 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, wherein the prioritization ratio (AuxPrio) is or can be predetermined by a user of the vehicle (50) by means of a control element (3) provided for this purpose, or wherein the prioritization ratio (AuxPrio) is predetermined depending on an operating situation. Method according to claim 1, characterized in that the determination of the target DC currents (x.I_DC_Des) starting from the target torque (x.T_Des) or the target speed (x.n_Des) or the target phase currents is carried out using at least one characteristic map (x.Map2). Method according to claim 2, characterized in that a target direct current (x.I_DC_Des) determined by means of the at least one characteristic map (x.Map2) is converted into a target torque (x.T_Des-CurrLim) after division by means of an inverted characteristic map (x.Map2_inv) corresponding to the at least one characteristic map (x.Map2), from which the respective electric drive (51,52) is controlled. Method according to one of the preceding claims, characterized in that an actual on-board DC current (I_Con_Act) is detected and used alternatively or additionally to the target on-board DC current (I_Con_Des) when splitting. Method according to one of the preceding claims, characterized in that actual DC currents (x.I_DC_Act) for the two electric drives (51, 52) are detected, wherein, when splitting, the detected actual DC currents (x.I_DC_Act) are used alternatively or additionally to the target DC currents (x.I_DC_Des). Method according to one of the preceding claims, characterized in that actual DC currents (x.I_DC_Act) for the two electric drives (51, 52) are detected, wherein the respective target DC currents (x.I_DC_DesLim) of the two electric drives (51, 52) limited by the division are controlled starting from the respective detected actual DC currents (x.I_DC_Act). Device (1) for controlling a current flow in a vehicle (50), wherein the vehicle (50) has two electric drives (51, 52) and an energy storage device (53), wherein one electric drive (51) is a traction drive and the other electric drive (52) is an auxiliary drive for a power take-off shaft or hydraulics, wherein the two electric drives (51, 52) and an on-board electrical system (54) are supplied by means of the energy storage device (53) or supply the energy storage device (53), comprising: a control device (2), wherein the control device (2) is configured to distribute an energy storage direct current (I_Bat) to the on-board electrical system (54) and the two electric drives (51, 52), and for this purpose - each starting from a target torque (x.T_Des) or a target speed (x.n_Des) or target phase currents - target direct currents (x.to determine the I_DC_Des for the two electric drives (51, 52), and to distribute a direct current flow between the energy storage device (53), the vehicle electrical system (54), and the two electric drives (51, 52) such that a maximum amount of an energy storage direct current (I_Bat_Lim) is not exceeded and that a target vehicle electrical system direct current (I_Con_Des) is provided with the highest priority, and to distribute a direct current resulting after provision of the target vehicle electrical system direct current (I_Con_Des) to the 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, wherein an operating element (3) is provided which is configured so that the prioritization ratio (AuxPrio) can be specified by a user, or wherein the control device (2) is configured to determine the prioritization ratio (AuxPrio) depending on to specify a business situation. Vehicle (50) comprising at least one device (1) according to claim 7.

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