Method for the demand-based operation of an electric traction drive for a motor vehicle

Abstract

Method (100) for the demand-based operation of an electric traction drive, wherein the electric traction drive comprises a hydraulic arrangement (1) with an electric motor-pump unit (2), wherein the motor-pump unit (2) is controllable in two directions of rotation, namely in a first direction of rotation (A) and in a second direction of rotation (B) opposite to the first direction of rotation (A), and wherein several pump operating modes are adjustable, and wherein the motor-pump unit (2) is connected via a heat exchanger (3) to at least two fluid outlets (4a, 4b, 4c) for partial volume flows, which are connected to at least one subcomponent (R, S, GBX, 13, 3) of the electric traction drive for cooling and / or heating and / or lubrication, wherein at least one fluid outlet (4a, 4b, 4c) is additionally opened via at least one hydraulically switchable valve (5) when a reversal of the direction of rotation of the Motor-pump unit (2) is controlled,wherein the motor-pump unit (2) is activated based on measured, calculated and / or stored state data of the electric traction drive and, based on a detected vehicle operating mode (1000, 2000, 3000, 4000), the direction of rotation (A, B) and thus the pump operating mode as well as a pump speed are controlled.

Description

Field of the invention

[0001] The present invention relates to a method for the demand-based operation of an electric traction drive, wherein the electric traction drive has an electrically controllable motor-pump unit and a hydraulic arrangement. State of the art

[0002] Conventional, combustion-engine-powered vehicles are now being replaced by electric and partially electric vehicle drive concepts. With the elimination of the combustion engine as a reliable heat source for interior climate control and the heating and cooling requirements of new drive components in electric and partially electric drive concepts, heating, cooling, and lubrication systems are also undergoing fundamental changes. The focus of developing such systems is on efficient and demand-based use of available energy, taking all safety-relevant framework conditions into account, and thus range-optimized operation of electrically powered vehicles.

[0003] The document WO 2023 / 006 218 A1, for example, discloses an electric drive for a vehicle, comprising a housing, an electric machine with a stator connected to the housing, a rotor rotatable relative to the stator, a drive shaft connected to the rotor and mounted in the housing for rotation about an axis of rotation, a transmission for transmitting a rotary movement from the drive shaft to drive a drive train of the vehicle, and a hydraulic circuit for circulating a fluid. Summary of the invention

[0004] It is an object of the invention to provide an improved method for the demand-based operation of an electric traction drive.

[0005] This need can be met by the subject matter of the present invention according to independent claim 1. Advantageous embodiments of the present invention are described in the dependent claims.

[0006] The method according to the invention serves to operate an electric traction drive as required.

[0007] According to the invention, the electric traction drive comprises a hydraulic arrangement with an electric motor-pump unit, wherein the motor-pump unit can be controlled in two directions of rotation, namely in a first direction of rotation and in a second direction of rotation opposite to the first direction of rotation, and thus several pump operating modes can be set.

[0008] Furthermore, according to the invention, the motor-pump unit is connected via a heat exchanger to at least two fluid outlets for partial volume flows, which are each connected to at least one subcomponent of the electric traction drive for cooling and / or heating and / or lubrication, wherein at least one fluid outlet is additionally opened or closed via at least one hydraulically switchable valve when the direction of rotation of the motor-pump unit is reversed.

[0009] According to the invention, the motor-pump unit is activated based on measured, calculated and / or stored status data of the electric traction drive, and based on a detected vehicle operating mode, the direction of rotation and thus the pump operating mode as well as a pump speed are controlled.

[0010] The vehicle operating mode is preferably selected by a vehicle driver, a higher-level driving mode controller and / or based on route data.

[0011] In addition to a passive pump operating mode, namely a pump standstill mode in which the motor-pump unit is not in operation, at least three active pump operating modes can be set according to the invention, namely a first pump operating mode in which the electric motor of the motor-pump unit is operated with speed control in the first direction of rotation of the electric motor, a second pump operating mode in which the electric motor of the motor-pump unit is operated with speed control in the second direction of rotation and / or a third pump operating mode in which the electric motor of the motor-pump unit is operated in reverse with speed control in the first direction of rotation and the second direction of rotation.

[0012] The motor-pump unit is preferably controlled into a pump operating mode based on temperature data of the subcomponents of the electric traction drive that are measured, calculated and / or stored for the individual vehicle operating modes.

[0013] When approaching and / or exceeding and / or falling below a limit value defined for the respective subcomponent of the electric traction drive, a cooling and / or heating requirement is determined, preferably for each of the subcomponents of the electric traction drive, and a total cooling and / or heating requirement is calculated, whereby the direction of rotation and thus the pump operating mode and the pump speed are controlled on the basis of the total cooling and / or heating requirement.

[0014] Furthermore, during active cooling and / or heating and / or lubrication of the electric traction drive, an actual total volume flow of fluid in the hydraulic arrangement is preferably determined, which is compared with a defined target total volume flow, wherein in the event of a deviation of the actual total volume flow from the target total volume flow for a defined period of time, alternating operation of the motor-pump unit in the first direction of rotation and in the second direction of rotation at maximum pump speed is controlled, and this is repeated until the actual total volume flow no longer deviates from the target total volume flow. Brief description of the drawings

[0015] The invention is described below by way of example with reference to the drawings. Fig. 1 shows a hydraulic arrangement of an electric traction drive. Fig. 2 shows a schematic sequence of a method for operating an electric traction drive. Fig. 3 shows a detailed flow chart for a first block of Fig. 2. Fig. 4 shows a detailed flow chart for a second block of Fig. 2. Fig. 5 shows a detailed flow chart for a third block of Fig. 2. Fig. 6 shows a detailed flow chart for a fourth block of Fig. 2. Fig. 7 shows a detailed flow chart for a fifth block of Fig. 2. Fig. Figure 8 shows a schematic sequence for switching between vehicle operating modes. Fig. Figure 9 shows a table of conditions for transitions between vehicle operating modes. Detailed description of the invention

[0016] In Fig. Figure 1 shows, by way of example, a simplified circuit diagram of a hydraulic arrangement 1 of an electric traction drive, in which the method 100 according to the invention is applied. However, the application of the method 100 according to the invention is not limited to exactly this illustrated embodiment variant—the illustrated embodiment variant serves merely as a basis for describing the method 100 according to the invention.

[0017] In addition to an electric machine as traction machine and a transmission arrangement GBX, the electric traction drive has a hydraulic arrangement 1 with an electric motor-pump unit 2.

[0018] The electric machine can be operated as a motor or generator and has a fixed stator S and a rotating rotor RS.

[0019] The electric motor-pump unit 2 has a fluid pump 6 and an electric motor 7, wherein the fluid pump 6 can be driven via the electric motor 7 in two directions of rotation, namely in a first direction of rotation A and in a second direction of rotation B opposite to the first direction of rotation A.

[0020] The electric motor 7 of the motor-pump unit 2 is controlled via an electrical control unit 8, which is connected to a data interface 9. The control unit 8 is connected to the electric motor 7 via a control line 10.

[0021] The fluid pump 6 is connected on the suction and pressure sides to a fluid sump 13, in the present embodiment to an oil sump, via a first check valve 11a and a second check valve 11b, as well as a filter element 12. Depending on the direction of rotation A, B of the fluid pump 6 of the motor-pump unit 2, one of the two check valves 11a, 11b is in an open position and the other of the two check valves 11a, 11b is in a closed position.

[0022] By means of the method 100 for operating the electric traction drive, in addition to lubrication, the functions of cooling, heating, and pre- and post-conditioning of the electric traction drive, as well as switching between these functions for optimal energy distribution within the system, can be implemented. For this purpose, the electric traction drive is divided into subcomponents, with each subcomponent being able to make a cooling or heating request. In the present exemplary embodiment, the electric machine, more precisely its stator S and its rotor R, the gear assembly GBX, the fluid sump 13, the heat exchanger 3, and the hydraulic assembly 1, each represent a subcomponent of the electric traction drive.

[0023] The motor-pump unit 2 of the hydraulic arrangement 1 is connected via a shuttle valve 14 and a heat exchanger 3 located upstream of the shuttle valve 14 to three fluid outlets 4a, 4b, 4c for partial volume flows - a first fluid outlet 4a is fluidly connected to the gear arrangement GBX of the electric traction drive, a second fluid outlet 4b is fluidly connected to the stator S of the electric machine of the traction drive and a third fluid outlet 4c is fluidly connected to the rotor R of the electric machine of the electric traction drive.

[0024] The third fluid outlet 4c can be opened and closed via a hydraulically switchable valve 5.

[0025] In Fig. 2, the sequence of the method 100 for the demand-based operation of the electric traction drive is shown schematically.

[0026] The method 100 for the demand-based operation of an electric traction drive provides different pump operating modes that depend on a vehicle operating mode 1000, 2000, 3000, 4000 selected by the driver of a vehicle or by an automated selection of a higher-level operating strategy, for example based on a selected route, a system state, a prediction from a current operating state, etc.

[0027] In the present, non-limiting, embodiment, the vehicle driver and / or a higher-level control unit should be able to choose between the following four vehicle operating modes 1000, 2000, 3000, 4000: - Basic Mode 1000: This mode serves as the standard driving mode, in which all requirements for the defined boundary conditions are met. The evaluation is based on a balanced and realistic driving cycle that goes beyond the "WLTC" standard (Class C of the "WLTP": "Worldwide Harmonized Light-Duty Vehicles Test Procedure"), whereby all requirements of the "WLTC" are also met. Power limits are maintained for defined times, and temperatures remain within the defined ranges or below defined limits. - “Performance” mode 2000: In both partially and purely oil-cooled electric traction machines, the cooling oil requirement of the rotor and stator varies depending on the respective operating point, particularly due to the copper, iron, and magnet losses occurring in the electric machine. To ensure maximum thermal availability, i.e., the longest and highest possible power availability of the electric machine, the oil mass flow and distribution between the rotor and stator are adjusted predictively and according to demand. The focus is on the thermal state in order to keep all subcomponents of the electric traction drive below their critical temperatures for as long as possible, thus maximizing thermal availability. Increasing energy efficiency plays only a minor role in this mode. - “Efficiency” mode 3000: In this mode, the energy consumption of the electric traction drive is minimized for any given driving cycle, while maximizing its efficiency. This is achieved by considering the overall energy consumption of the electric traction drive. In addition to the components of the electric traction drive's electric motor, the reduction gear and the cooling oil are kept within specific temperature limits to operate the electric traction drive at its best thermal efficiency point. Factors taken into account include hydraulic drag losses and the electrical drive power of the electric motor-pump unit. By distributing the generated heat as needed, the temperatures of different areas or subcomponents can be specifically raised or lowered to achieve the most energy-efficient operating point from the overall system perspective. - “Conditioning” mode 4000: A distinction is made between pre-conditioning and post-conditioning of the electric traction drive. The "conditioning" mode is activated when the vehicle is stationary. Before or after operation of the electric traction drive, it may be necessary to condition the system in order to ensure continued efficient operation or to protect it from damage. Before starting, for example, it makes sense to preheat the system slightly at low temperatures to reduce losses. After operation, active cooling may be necessary if the system is brought to a standstill (turned off, parked) within a very short time, for example, from high-load operation such as at maximum speed. During preconditioning - mainly during cold starts - the subcomponents of the electric traction drive, such as the GBX transmission arrangement and the electric motor, are tempered to operating temperatures that optimize efficiency before the actual journey. Post-conditioning is mainly used after journeys with increased power requirements in order to cool the high temperatures of the subcomponents of the electric traction drive to conventional operating temperatures.

[0028] The motor-pump unit 2 is activated based on measured, calculated and / or stored status data of the electric traction drive and based on a detected vehicle operating mode 1000, 2000, 3000, 4000, the direction of rotation and thus the pump operating mode as well as a pump speed are controlled.

[0029] The pump operating modes are set by switching the direction of rotation A, B of the motor-pump unit 2. Switching the direction of rotation changes the fluid distribution to the rotor R and stator S of the electric machine of the electric traction drive, whereby a constant, small volume flow is always conducted through the GBX gear arrangement. Furthermore, in addition to the two directions of rotation A, B with constant percentage distributions, an intermittent reversing operation is also represented, in which the flow rates between the limits of the two directions of rotation A, B can be mapped over time.

[0030] In summary, three pump operating modes can be controlled: - a first pump operating mode in which the electric motor of the motor-pump unit 2 is operated with speed control in the first direction of rotation A of the electric motor, - a second pump operating mode in which the electric motor of the motor-pump unit 2 is operated with speed control in the second direction of rotation B and / or - a third pump operating mode in which the electric motor of the motor-pump unit 2 is reversed with speed control in the first direction of rotation A and the second direction of rotation B.

[0031] In a first step, the method 100 includes several query blocks 101, 102, 103. Query block 101 queries whether active cooling of the electric traction drive or at least one of its subcomponents is required. Query block 102 queries whether active heating of the electric traction drive or at least one of its subcomponents is required. Query block 103 queries whether conditioning of the electric traction drive or at least one of its subcomponents is required. If all of these query blocks 101, 102, 103 are answered with "no," the electric motor-pump unit 2 does not need to be controlled into operation—it is in a passive pump standstill mode (block 200). If one of the query blocks is answered with "yes," the electric motor-pump unit 2 is controlled or set into an active pump operating mode (block 300) ( Fig. 2).

[0032] For the optimal operation of the electric traction drive, several predefined function blocks 400, 500, 600, 700, 800, 900 are subsequently executed, depending on whether query blocks 101, 102, 103 are answered with “yes”, whereby in the case of the two query blocks 101 and 102 for cooling and / or heating, the same function blocks are executed in the same order, namely ( Fig. 2) - a function block “Set operating mode and load parameterization” 400 - a function block “Determination of influencing factors” 500 - a function block “Scaling and calculation of pump speed” 600 - a function block “Diagnosis” 700 - a function block “Releasing a jammed fluid pump” 800 and - a function block “additional application-specific function blocks” 900.

[0033] In the case of the query block 103 for conditioning, the following function blocks run in sequence ( Fig. 2): - the function block “Set operating mode and load parameterization” 400 - the function block “Scaling and calculation of pump speed” 600 - the function block “Diagnosis” 700 - the function block “Releasing a jammed fluid pump” 800 and - the function block “additional application-specific function blocks” 900.

[0034] In the Fig. 3 to Fig. 7 the individual function blocks 400, 500, 600, 700, 800, 900 are shown in detail.

[0035] Fig. Figure 3 shows the function block "Set operating mode and load parameterization" 400 in detail. In this function block 400, three query blocks 401, 402, and 403 run sequentially. Query block 401 queries whether "Performance" mode 2000 is permitted and active. Query block 402 queries whether "Efficiency" mode 3000 is permitted and active. Query block 403 queries whether "Conditioning" mode 4000 is permitted and active. If each of these query blocks is answered with "no," function block 414 "Load parameterization for basic mode" is executed. If query block 401 is answered with "yes," function block 411 "Load parameterization for performance mode" is executed. If query block 402 is answered with "yes," function block 412 "Load parameterization for efficiency mode" is executed. If query block 403 is answered with "yes," function block 413 "Load parameterization for conditioning mode" is executed.

[0036] The method 100 for operating the electric traction drive uses so-called influencing factors. Each subcomponent can report a fluid flow requirement for cooling and / or heating and / or conditioning and / or lubrication. The sum of all requirements results in the total requirement for the electric traction drive. In addition to the quantity, the direction of rotation A, B of the fluid pump 6 can also be defined by selected subcomponents. In the event that neither of the two directions of rotation A, B is suitable, the hydraulic arrangement also offers the option of intermittent reversing operation, i.e., the third pump operating mode. In this mode, a flow in both directions is created on average over time, which lies between the flow rates in the two directions of rotation A, B.

[0037] These two variables—speed and direction of rotation—are then scaled to the hydraulic arrangement 1, and a corresponding speed of the fluid pump 6 is output. This speed can also be limited by various influencing factors.

[0038] Method 100 is fully parameterizable, allowing it to be easily scaled and applied to different electric traction drives. Individual subfunctions can be deactivated, and all setpoints and characteristic maps can be freely parameterized.

[0039] The vehicle operating mode 1000, 2000, 3000, or 4000 is selected by the driver and / or by automated selection via a control unit. The selected vehicle operating mode 1000, 2000, 3000, or 4000 optimizes the target values ​​and parameterization (characteristic maps and lookup tables). Interpolation of the values ​​is performed for a potentially necessary transition phase between the vehicle operating modes 1000, 2000, 3000, and 4000.

[0040] If a switch between two vehicle operating modes (1000, 2000, 3000, or 4000) is requested, a check is carried out to determine whether such a switch is currently permitted and possible. Especially when switching to "Performance" mode 2000, the temperature levels and cooling capacity must be met, as this vehicle operating mode is expected to result in increased power loss and thus a higher thermal load.

[0041] If a direct switch to the desired vehicle operating mode (1000, 2000, 3000, or 4000) is not possible, an attempt is made to put the system into the appropriate state—this can take up to several minutes, depending on the system. Optionally, feedback can be sent to the driver indicating when the "new" operating mode will be fully available.

[0042] The selectable vehicle operating modes 1000, 2000, 3000, 4000 define a thermal target state to achieve the respective target of the vehicle operating mode 1000, 2000, 3000, 4000.

[0043] Fig. Figure 4 shows the "Determination of Influencing Factors" function block in detail. In this function block 500, four function blocks 501, 502, 503, and 504 run in parallel. Function block 501 determines the cooling and / or heating requirement of the rotor R of the electric motor of the electric traction drive. Function block 502 determines the cooling and / or heating requirement of the stator S of the electric motor of the electric traction drive. Function block 503 determines the cooling and / or heating requirement of the fluid sump 13 of the hydraulic arrangement 1 of the electric traction drive. Function block 504 determines the cooling requirement based on the load point and temperature gradient. The determined cooling and / or heating requirements result in a function block 512 "Calculate Total Influencing Factor."From the determination of the cooling and / or heating requirement, the function block 501 also results in the function block 512 for determining the direction of rotation A, B of the fluid pump 6 of the motor-pump unit 2 of the hydraulic arrangement 1.

[0044] Fig. Figure 5 shows the function block "Scaling and Calculation of Pump Speed" 600 in detail. In this function block 600, three function blocks 601, 602, and 603 run sequentially. Function block 601 calculates the pump speed of fluid pump 6. Function block 602 suppresses rapid pump speed changes, for example, to minimize the NVH behavior and energy consumption of fluid pump 6. Function block 603 limits the pump speed according to the current vehicle operating state (1000, 2000, 3000, 4000).

[0045] Fig. Figure 6 shows the function block “Diagnosis” 700 in detail. In this function block 700, four function blocks 500, 600, 701, 702 run in sequence. The first two function blocks 500 and 600 have already been described using Fig. 4 and Fig. 5. In function block 701, the current fluid circulation rate is determined. In function block 702, a plausibility check of the target pump speed and flow rate is performed, followed by query block 703, whether "VF current ≤ VF target." If query block 703 is answered with "no," the "diagnosis is OK" 704. If this query block is answered with "yes," the function block "Release of a jammed fluid pump" 800 is executed according to Fig. 7.

[0046] Fig. Figure 7 shows the function block "Releasing a jammed fluid pump" 800 in detail. In this function block 800, four function blocks 801, 802, 803, 800 run sequentially. In function block 801, the fluid pump 6 is operated alternately in the first direction of rotation A and in the second direction of rotation B with the maximum speed of the fluid pump 6 for a defined period of time. This function block 801 can be repeated up to three times. In function block 802, the fluid pump is operated with a defined test speed and test direction of rotation A, B. In function block 803, a plausibility check is carried out, followed by query block 804, whether "VF is t ≤ (VF soll + ΔVF)". If this query block 804 is answered with "no", the function block 700 is executed, as already described in Fig. 6. If this query block is answered with “yes”, function block 801 starts again, followed by function blocks 802, 803 and query block 804, whether “VF is t ≤ (VF soll + ΔVF)” and this continues until query block 804 is answered with “no”.

[0047] The Fig. The flowchart shown in Figure 8 schematically shows the transition between the various vehicle operating modes 1000, 2000, 3000, 4000, as well as the starting 9000 and stopping 7000 of the method 100 for operating the electric traction drive. The example vehicle operating modes 1000, 2000, 3000, 4000 do not all have to be used, but can also be expanded to include additional vehicle operating modes. Furthermore, a transition between the individual vehicle operating modes 1000, 2000, 3000, 4000 can also be blocked if it is not permitted.

[0048] If process 100 is started, a query is made as to whether conditioning is required (query block 8000). A 9000 start of process 100 is not equivalent to a 5000 vehicle start. If the electric traction drive is to be conditioned, a transition to "Conditioning" mode 4000 occurs; otherwise, it is switched to basic mode 1000. The initial mode can also be different depending on the definition and structure.

[0049] If the “Conditioning” mode 4000 is executed, when the vehicle starts 5000 there is an automatic transition from the “Conditioning” mode to the basic mode 1000 or the mode defined as initial.

[0050] A transition between the individual vehicle operating modes 1000, 2000, 3000, and 4000 always follows the same structure: the state of the electric traction drive is checked to determine whether it is permissible for the "new" vehicle operating mode 1000, 2000, 3000, and 4000 (query blocks 1001, 2001, and 3001). If all conditions are met, the system transitions to the new vehicle operating mode 1000, 2000, 3000, and 4000 (function blocks 1002, 2002, and 3002). If not all conditions are met, an attempt is made to set the electric traction drive to the appropriate state. If this is not possible, for example, after a defined time has elapsed, the current vehicle operating mode remains. Necessary conditions (but not limited to these) are the rotor R (magnet) temperature, the stator temperature, the fluid sump 13 temperature as well as fluid temperature and fluid flow.When the vehicle is stopped (parked) 6000, the system switches to “conditioning” mode 4000. Only after the electric traction drive is in a (thermally) safe state does the stopping 7000 of procedure 100 take place.

[0051] In Fig. 9 shows a table which shows, in the left column, examples of different transitions between the vehicle operating modes Basic Mode 1000, “Performance” Mode 2000 and “Efficiency” Mode 3000 and, in the right column, the conditions to be fulfilled for the transitions.

[0052] Depending on the desired vehicle operating mode 1000, 2000, 3000, 4000, the values ​​shown in the table may be Fig. 9 shown values ​​must not exceed or fall below certain parameters. For example, the current rotor temperature T Rotor, aktuell and the current stator temperature T Stator, aktuellFor "Performance" mode 2000, the temperature must be low enough, and sufficient cooling capacity must be available from the cooling fluid. In "Efficiency" mode 3000, higher temperatures may be permissible because lower power also results in fewer losses, but this places lower demands on the cooling fluid. Therefore, when transitioning to Base mode 1000 or "Performance" mode, the temperature levels of rotor R and stator S must be lowered first.

[0053] It should be noted that the exact limits and conditions depend heavily on the electric traction drive to which method 100 is applied. Furthermore, a higher-level vehicle operating strategy is a decisive factor for the parameterization.

[0054] In current electric traction drives, the available drive torque begins to be reduced above a defined temperature in order to thermally protect the electric traction drive and its subcomponents. This means that part of the performance potential remains unused ("torque derating"). By using hydraulic arrangement 1, the fluid volume flows can be flexibly adjusted, thus delaying the "torque derating," which means that more torque is available for a certain period of time even at higher temperatures. Specifically, the torque is only reduced at higher temperatures because the fluid volume flow is not only directly dependent on the electric motor of the electric traction drive, but can also be determined by other variables, such as temperatures and gradients, fluid flow and temperature, rotational speed of the electric motor, torque, etc. List of reference symbols 1 Hydraulic arrangement 2 Motor-pump unit 3 heat exchangers 4a First fluid outlet 4b Second fluid outlet 4c Third fluid outlet 5 Hydraulically switchable valve 6 Fluid pump 7 Electric motor 8 Control unit 9 Data interface 10 Control line 11a First check valve 11b Second check valve 12 filter element 13 Fluid sump 14 shuttle valve 100 101, 102, 103, 401, 402, 403, 703, 804, 1001, 2001, 3001, 8000 Method for operating an electric traction drive 200, 300, 400, 411, 412, 413, 414, 500, 501, 502, 503, 504, query block 511, 512, 600, 601, 602, 603, 700, 701, 702, 704, 800, 801, 802, 803, 900, 1002, 2002, 3002 Function block 1000 Base Mode 2000 “Performance” mode 3000 “Efficiency” mode 4000 “Conditioning” mode 5000 vehicle starts 6000 Vehicle stop (parking the vehicle) 7000 proceedings stopped 9000 procedure start R Rotor S Stator GBX gear arrangement T Temperature T Stator, aktuell Current stator temperature T Rotor, aktuell Current rotor temperature T Stator, max Maximum stator temperature T Rotor, max Maximum rotor temperature ΔT Stator, XXX Temperature difference limit stator in XXX mode (XXX = Basis, Performance, Efficiency) ΔT Rotor, XXX Temperature difference limit rotor in XXX mode (XXX = Basis, Performance, Efficiency) T Ölsumpf Oil sump temperature T Ölsumpf, XXX Oil sump temperature limit in XXX mode (XXX = Basis, Performance, Efficiency) QF heat flow QF Kühlwasser Heat flow cooling water QF XXX,minHeat flow limit in XXX mode (XXX = Basis, Performance, Efficiency) VF volume flow VFist actual volume flow VFsoll Target volume flow ΔVF Difference between an actual volume flow and a target volume flow + "yes" - "no"

Claims

[1] Method (100) for the demand-based operation of an electric traction drive, wherein the electric traction drive has a hydraulic arrangement (1) with an electric motor-pump unit (2), wherein the motor-pump unit (2) is controllable in two directions of rotation, namely in a first direction of rotation (A) and in a second direction of rotation (B) opposite to the first direction of rotation (A), and thus several pump operating modes can be set, and wherein the motor-pump unit (2) is connected via a heat exchanger (3) to at least two fluid outlets (4a, 4b, 4c) for partial volume flows, which are connected for cooling and / or heating and / or lubrication to at least one subcomponent (R, S, GBX, 13, 3) of the electric traction drive, wherein at least one fluid outlet (4a, 4b, 4c) is additionally opened via at least one hydraulically switchable valve (5) when a reversal of the direction of rotation of the motor-pump unit (2) is controlled,wherein the motor-pump unit (2) is activated based on measured, calculated and / or stored status data of the electric traction drive, and based on a detected vehicle operating mode (1000, 2000, 3000, 4000), the direction of rotation (A, B) and thus the pump operating mode as well as a pump speed are regulated, wherein in addition to a passive pump operating mode, namely a pump standstill mode in which the motor-pump unit (2) is not in operation, at least three active pump operating modes can be set, namely a first pump operating mode in which the electric motor of the motor-pump unit (2) is operated with speed control in the first direction of rotation (A) of the electric motor, a second pump operating mode in which the electric motor of the motor-pump unit (2) is operated with speed control in the second direction of rotation (B), and / or a third pump operating mode,in which a reverse operation of the electric motor of the motor-pump unit (2) with speed control in the first direction of rotation (A) and the second direction of rotation (B) takes place., [2] Method (100) according to claim 1, characterized by that the vehicle operating mode (1000, 2000, 3000, 4000) is selected by a vehicle driver or by an automated selection via a control unit. [3] Method (100) according to claim 1 or 2, characterized by that the motor-pump unit (2) is controlled into a pump operating mode based on temperature data of the subcomponents (R, S, GBX, 13, 3) of the electric traction drive that are measured, calculated and / or stored for the individual vehicle operating modes (1000, 2000, 3000, 4000). [4] Method (100) according to claim 3, characterized bythat when approaching and / or exceeding and / or falling below at least one limit value defined for the respective subcomponent (R, S, GBX, 13, 3) of the electric traction drive, a cooling and / or heating requirement is determined for each of the subcomponents and a total cooling and / or heating requirement is calculated, wherein the direction of rotation (A, B) and thus the pump operating mode and the pump speed are regulated on the basis of the total cooling and / or heating requirement. [5] Method (100) according to one of claims 1 to 4, characterized bythat during active cooling and / or heating and / or lubrication of the electric traction drive, an actual total volume flow of fluid in the hydraulic arrangement (1) is determined, which is compared with a defined target total volume flow, wherein in the event of a deviation of the actual total volume flow from the target total volume flow for a defined period of time, alternating operation of the motor-pump unit (2) in the first direction of rotation (A) and in the second direction of rotation (B) at maximum pump speed is regulated, and this is repeated until the actual total volume flow no longer deviates from the target total volume flow.

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