Actuating device for a steering system of a vehicle, in particular of a motor vehicle, and method for steering a vehicle, in particular a motor vehicle

Abstract

The invention relates to an actuating device (1) for a steering system of a vehicle, wherein - the actuating device (1) generates a manipulated variable on the basis of an obtained steering specification, by means of which manipulated variable a steering angle of the steering system is set, - the actuating device (1) has at least two redundant control and supply apparatuses (11a, 11b) which each control an associated actuating drive (12a, 12b) and supply it with electrical energy in order to set an actuating force by means of the actuating drive, by means of which actuating force the steering angle is set, and - for a normal operation, in which the at least two redundant control and supply apparatuses (11a, 11b) are functional, for each of the control and supply apparatuses (11a, 11b) a maximum value associated therewith is defined for a contribution, associated therewith, to the actuating force, so that a maximum magnitude of the manipulated variable required for normal operation is achieved by the sum of the contributions in the case of the maximum values, wherein the actuating device (1), in a fault mode in which one (11b) of the at least two redundant control and supply apparatuses (11a, 11b) is not functional with regard to the application of its contribution and / or its contribution cannot be converted into an actuating force in which, however, a remaining control and supply apparatus (11a) and the associated actuating drive (12a) are functional, is designed to apply its contribution and convert it into an actuating force, - to operate the remaining functional control and supply apparatus (11a) in such a way that it makes or causes a contribution to the manipulated variable or to the sum of the manipulated variables which is higher than the maximum value associated therewith in normal operation.

Description

Description Actuating device for a steering system of a vehicle, in particular a motor vehicle, and method for steering a vehicle, in particular a motor vehicle

[0001] The invention relates to an actuating device for a steering system of a vehicle, in particular a motor vehicle, and a method for steering a vehicle, in particular a motor vehicle.

[0002] Steer-by-wire (SbW) steering systems, which will be used in mass production in the automotive sector in the future, must exhibit significantly higher reliability than conventional steering systems. This is because SbW steering systems have no mechanical connection between the steering wheel and the steering gear. A complete failure of the electrical component of the steering system would render the vehicle unsteerable.

[0003] Key components of a side-by-side (SbW) steering system typically include a force-feedback actuator (FFA), which detects the desired steering angle and provides feedback to the driver, and a controlled steering gear (SbW-EPS, electric power steering), which translates the driver's input received from the FFA into a steering movement. More generally, an SbW steering system usually incorporates an actuator that, depending on a steering input received from the driver or from the vehicle's automatic steering or steering assistance system, generates a control variable (e.g., a force or torque) or a combination of control variables to adjust the steering angle.

[0004] The safe state in the SbW system is "fail-operational," meaning that after an initial vehicle failure, the steering functions must remain available. Switching off the SbW steering system is impossible. This necessitates a redundant actuator design, specifically with at least two control and power supply units, each controlling and supplying electrical energy to an actuator. In practice, the actuators are often implemented as separate inverters, each with an electrically connected stator winding assembly. The rotating magnetic field generated by the various stator winding assemblies acts on a common rotor. In other words, the various stator winding assemblies and the rotor form a common electric motor that can still be operated even if only one of the stator winding assemblies is energized.Any combination of one of the stator winding arrangements with the rotor can be considered a partial motor.

[0005] Requirements for SbW steering systems are defined in DIN 70065 (currently valid: DIN 70065:2024). These include minimum requirements for the lateral control and controllability of the vehicle after an initial fault. An initial fault is, for example, the failure of one of the redundant control and power supply units, particularly if one of the control and power supply units is no longer supplied with electrical energy by the vehicle's electrical system. Another initial fault is, for example, a malfunction of the inverter of one of the control and power supply units and / or the inverter's control system. To meet the aforementioned minimum requirements, the steering system must still maintain a lateral control velocity of 4 m / s after the initial fault occurs. 2can be applied. Therefore, if one of two actuators fails, the other actuator (in so-called single-channel operation) must provide the required lateral guidance. Typically, if the steering system has a rack and pinion steering gear, the remaining actuator must provide sufficient rack force for the vehicle to meet this requirement. The required rack force (or more generally, the actuating force or torque) depends on the vehicle's front axle load, axle kinematics, and other influencing factors. Consequently, there are various operating situations in which different minimum actuating forces or torques must be applied.

[0006] The mechanical and / or electrical design of the SbW steering system can be tailored for a parking operation and / or for defined driving situations (especially maneuvers), typically for at least one operating situation in which the highest actuating forces or torques, particularly rack forces, occur. For example, the design can be based on a lateral acceleration of 8 m / s² required in the operating situation. Due to the requirements of single-channel operation, the overall performance design is now determined by the minimum required lateral guidance in this single-channel operating state. In other words, the SbW steering system is designed mechanically and electrically such that if one actuator fails, the remaining actuator(s) meet the minimum requirements, particularly for the aforementioned at least one operating situation (e.g., parking operation or maneuver).

[0007] The invention is not limited to SbW steering systems, but also relates to other types of steering systems, in particular electromechanical and / or electrohydraulic steering systems, in a configuration with redundant actuators. An example of another type of steering system is a steering system with superimposed steering.

[0008] The invention can be implemented in particular as described above, but with the additional features described below.

[0009] It is an object of the present invention to provide an actuating device for a steering system of a vehicle, in particular a motor vehicle, with which the manufacturing effort can be reduced. It is a further object to provide a corresponding method for steering a vehicle, in particular a motor vehicle.

[0010] As already explained above, the invention relates to an actuator for a vehicle's steering system, in particular a motor vehicle, which has at least two mutually redundant control and supply units. These are each configured to control and supply an associated actuator with electrical energy in order to adjust an actuating force or torque by means of the actuator, thereby adjusting the steering angle. Since each of the control and supply units controls and supplies an associated actuator with electrical energy, there is at least one actuator. However, as already explained above, it is common practice for at least parts of the actuator to be designed redundantly, for example, as described above, the stator winding arrangements whose rotating magnetic fields act on the same rotor of a common electric motor.However, it is also possible for the control and supply units to control and supply electrical energy to separate actuators. For example, a first control and supply unit can supply a first electric motor, and a second control and supply unit can supply a second electric motor that shares no components with the first. Hybrid configurations of these designs are possible if more than two control and supply units are present.

[0011] The actuating force or torque by which the steering angle is adjusted is therefore generally generated by one or more actuators of the actuating device. Each actuator is associated with at least one of the control and supply units that control and supply the actuator(s) with electrical energy.

[0012] The manipulated variable(s) has / have a magnitude. In particular, the higher the value of the manipulated variable or the sum of the manipulated variables, the greater the actuating force or torque generated by the actuator. The actuating force or torque can be the manipulated variable or the sum of the manipulated variables. In this case, the control and supply units generate the manipulated variable or the sum of the manipulated variables. However, since the control and supply units each control and supply their assigned actuator with electrical energy, they do not directly generate the manipulated variable or the sum of the manipulated variables. The manipulated variables can also be output variables of the control and supply units, for example, the load currents at the outputs of the control and supply units. In this case, the control and supply units generate the manipulated variables.

[0013] For normal operation, in which at least two mutually redundant control and supply units and their respective associated actuators are functional, a maximum value is defined for each control and supply unit's contribution to the manipulated variable or the sum of the manipulated variables. Therefore, the sum of these contributions achieves the maximum manipulated variable or the required maximum sum of the manipulated variables required for normal operation. In particular, the actuator is designed and configured such that the maximum values ​​assigned to each control and supply unit for its respective contribution are not exceeded during normal operation. The same applies to the procedure for steering a vehicle. If, for example, the maximum value refers to the load current generated by the control and supply units, then the respective maximum load current value of each control and supply unit will not be exceeded during normal operation. This means that a clear basis exists, particularly for the electrical dimensioning of the control and supply units and their associated actuator(s). Furthermore, the control section of the respective control and supply unit can be designed to control the unit in such a way that the load current does not exceed its maximum current value. This can be achieved, in particular, by voltage or current control of semiconductor switches within the respective control and supply unit through which the load current flows.Voltage control of semiconductor switches with an isolated control electrode, usually referred to as the gate or money electrode, is preferred. Examples include FETs (field-effect transistors), in particular MOSFETs (metal-oxide-semiconductor field-effect transistors, whose semiconductor material is, for example, SiC), IGBTs (isolated-gate bipolar transistors), thyristors in general, GTOs (switchable-gate thyristors), and IGCTs (integrated-gate commutated thyristors).

[0014] In the event of a fault, at least one of the at least two mutually redundant control and supply units and / or the associated actuator will be inoperative. Therefore, if, for example, one of the aforementioned stator winding arrangements or one of the multiple electric motors is inoperative, then the contribution of the associated control and supply unit to the manipulated variable or to the sum of the manipulated variables that the actuator is intended to generate cannot be converted into an actuating force or torque. In other words, the contribution of the control and supply unit is eliminated if it itself and / or the associated actuator or actuator component (as in the case of multiple stator winding arrangements of the same electric motor) is inoperative.In this case of a fault, however, it can be assumed (and this is how it can be implemented in practice) that at least one remaining control and supply unit and the associated actuator are functional, able to contribute and convert into an actuating force or torque.

[0015] It is proposed to design the actuator or the method for steering a vehicle in such a way that in the event of a fault operation a remaining control and supply unit generates or causes a contribution to the manipulated variable or to the sum of the manipulated variables that is higher than its assigned maximum value, or to operate the remaining control and supply facilities in such a way that they generate or cause a sum of contributions to the control variable or to the sum of the control variables that is higher than the sum of the maximum values ​​assigned to them.

[0016] In particular, the remaining control and supply unit, or at least one remaining control and supply unit, can, in the event of a fault, increase the load current it generates to values ​​above its maximum value during normal operation if required (i.e., when a sufficiently strong control signal is needed to implement the steering input received from the driver or from an automatic steering system or steering assistance system of the vehicle in accordance with regulations, especially DIN 70065). Specifically, this allows the remaining control and supply unit to make a greater contribution to the overall steering system and the vehicle, particularly a greater contribution to the vehicle's lateral acceleration.

[0017] Unless explicitly stated otherwise in this description and the claims, the maximum value is understood to be that during normal operation. However, a separate maximum value may also be defined for each of the control and supply units during fault operation. This is preferred.

[0018] The advantage of this proposal is that the actuator can be designed for normal operation as usual, but with the option of increased power in the event of a fault. This utilizes the ability of actuators, particularly electric motors, to temporarily handle higher currents, which are not permissible for continuous operation. Therefore, if an initial fault occurs, the increased power can be used, especially in hazardous situations (e.g., requiring high steering forces at high speeds) or emergencies (e.g., parking to clear a lane for traffic). However, continued operation beyond the end of the hazardous or emergency situation can be prevented or restricted to an operating mode in which the increased power is no longer necessary.

[0019] In particular, in accordance with the above statements, the following is proposed: An actuating device for a steering system of a vehicle, in particular a motor vehicle, wherein the actuating device is designed to generate, depending on a steering input received from the driver or from an automatic steering device or steering assistance device of the vehicle, an actuating variable or a sum of actuating variables by which a steering angle of the steering system is set, The actuator has at least two mutually redundant control and supply units, each configured to control and supply electrical energy to an associated actuator in order to set an actuating force or torque by means of the actuator, thereby setting the steering angle, wherein each of the mutually redundant control and supply units is configured to generate or cause an associated contribution to the actuated variable or to the sum of the actuated variables, and For normal operation, in which at least two mutually redundant control and supply units and their respective associated actuators are functional, a maximum value for the contribution assigned to each control and supply unit is defined, such that the sum of the contributions achieves a maximum required strength of the manipulated variable or the required maximum strength of the sum of the manipulated variables for normal operation. wherein the actuator is designed to operate in a fault mode in which at least one of the at least two mutually redundant control and supply units is / are not functional with regard to providing its contribution and / or its contribution cannot be converted into an actuating force or torque, but in which at least one remaining control and supply unit and the associated actuator are functional to provide their contribution and convert it into an actuating force or torque, to operate a remaining functional control and supply unit in such a way that it generates or causes a contribution to the manipulated variable or to the sum of the manipulated variables that is higher than the maximum value assigned to it, or to operate the remaining functional control and supply units in such a way that they generate or cause a sum of contributions to the manipulated variable or to the sum of the manipulated variables,which is higher than the sum of the maximum values ​​assigned to them.

[0020] Accordingly, for the procedure for steering a vehicle, in particular a motor vehicle, it is proposed that An actuator to generate a control variable or a sum of control variables, depending on a steering input received from the driver or from an automatic steering system or steering assistance system of the vehicle, by which a steering angle is set. The actuator has at least two mutually redundant control and supply units, each of which controls and supplies electrical energy to an associated actuator in order to set an actuating force or torque by means of the actuator, by which the steering angle is set, wherein each of the mutually redundant control and supply units generates or causes an associated contribution to the actuated variable or to the sum of the actuated variables, and For normal operation, in which at least two mutually redundant control and supply units and their respective associated actuators are functional, a maximum value for the contribution assigned to each of the control and supply units is defined or will be defined, such that the sum of the contributions, in the case of maximum values, achieves a maximum required strength of the manipulated variable or a required maximum strength of the sum of the manipulated variables for normal operation. wherein the actuator, in a fault operation in which at least one of the at least two mutually redundant control and supply units is / are not functional with regard to providing its contribution and / or its contribution cannot be converted into an actuating force or torque, but in which at least one remaining control and supply unit and the associated actuator are functional, to provide their contribution and convert it into an actuating force or torque, operates the remaining control and supply unit in such a way that it generates or causes a contribution to the actuated variable or to the sum of the actuated variables that is higher than the maximum value assigned to it, or operates the remaining control and supply facilities in such a way that they generate or cause a total sum of contributions to the control variable or to the sum of the control variables that is higher than the sum of the maximum values ​​assigned to them.

[0021] The following describes embodiments of the actuator and the method for steering a vehicle, parts of which may be the subject of dependent patent claims. The description of embodiments of the actuator implies corresponding embodiments of the method, and vice versa.

[0022] According to a preferred embodiment, the at least two mutually redundant control and supply units each have at least one power converter (in particular, an inverter) with a plurality of controllable semiconductor switches (preferably the aforementioned semiconductor switches with insulated gate electrodes). During operation, the semiconductor switches are repeatedly switched on and off, generating an electrical load current which is supplied to the associated actuator to adjust the steering angle. The associated maximum value for normal operation is a maximum current value for the load current flowing through the controllable semiconductor switches. In fault operation (and especially when required) - a controller controls the controllable semiconductor switches of at least one power converter of the remaining control and supply unit in such a way that a stronger load current than its assigned maximum value flows through the controllable semiconductor switches, or - a controller controls the controllable semiconductor switches of at least one of the remaining control and supply devices in such a way that a stronger load current flows through these controllable semiconductor switches than the maximum value assigned to at least one of the remaining control and supply devices.

[0023] This design of the positioning device and the method has the advantage that it can be easily implemented using means known for positioning devices.

[0024] In particular, the power converter is such a converter that is designed as a three-phase AC voltage converter on its AC voltage side connected to the associated actuator. Specifically, compared to the maximum value during normal operation, the RMS value of the current in each phase is increased during fault operation.

[0025] Preferably, the controllable semiconductor switches are voltage-controlled with respect to the load current, and the control system controls the control electrodes of the controllable semiconductor switches in fault mode such that they are brought to a higher electrical voltage than in normal operation. Increasing the control voltage increases the load current. To implement this, it is only necessary to provide the control system with a setting for a higher control voltage for the load current in fault mode. Since the semiconductor switches are repeatedly switched on and off in both normal and fault modes, the increased control voltage in fault mode is reached at the end of each switching-on cycle of the respective semiconductor switch.If the control electrode of the respective semiconductor switch is an isolated gate, a gate driver circuit is used, as is generally known, to electrically charge the gate in order to turn on the semiconductor switch. Typically, a supply voltage for the gate driver circuit is used to generate the gate charging current. In the case of the maximum value during normal operation, at the end of the charging process, when the semiconductor switch is turned on, the voltage at the gate relative to the source or emitter (the designation depends on the type of semiconductor switch) reaches the supply voltage. However, it is also possible for a predetermined fraction of the supply voltage to be reached at the end of the charging process. If the contribution is not set according to the maximum value during normal operation, the gate charging process can be terminated when a lower voltage is reached, thus reducing the load current.

[0026] Several options exist for fault operation. Firstly, the supply voltage can be increased compared to normal operation. Alternatively or additionally, the specified fraction of the supply voltage corresponding to the maximum adjustable load current can be changed, and in particular, increased. Both measures, or a combination thereof, enable the setting of a higher load current than in normal operation.

[0027] More generally, controllable semiconductor switches are voltage-controlled semiconductor switches with respect to the strength of the load current, and the control system controls the control electrodes of the controllable semiconductor switches in fault operation in such a way that they are brought to a higher electrical voltage than in normal operation.

[0028] The scope of the invention also includes a steering system with the actuating device in any of the embodiments described in this description and a vehicle, in particular a motor vehicle with a steering system which includes the actuating device in any of the embodiments described in this description.

[0029] Exemplary embodiments of the invention will now be described with reference to the accompanying drawing. The individual figures in the drawing show:

[0030] Fig. 1 schematically shows an actuating device with two mutually redundant control and supply units, each controlling and supplying electrical energy to an actuator in order to adjust an actuating force or torque on a steering gear by means of the actuator, thereby adjusting the steering angle.

[0031] Fig. 2 shows an inverter connected to an actuator,

[0032] Fig. Its semiconductor switch of the inverter shown in Fig. 2 and a driver circuit for switching the semiconductor switch on and off.

[0033] The actuator 1 shown in Fig. 1 has two mutually redundant control and supply units 11a, 11b, each of which controls and supplies electrical energy to an actuator 12a, 12b in order to adjust an actuating force or torque on a steering gear 4 by means of the actuator 12a, 12b, thereby adjusting the steering angle, in particular of at least one wheel of a front axle of a motor vehicle. In the specific embodiment shown in Fig. 1, two separate actuators 12a, 12b are present. As already mentioned, however, only one actuator may also be present, which, however, has two separate stator winding arrangements, each of which is controlled and supplied with electrical energy by one of the control and supply units.

[0034] In normal operation, the two combinations of a control and supply unit 11a, 11b with an actuator 12a, 12b each contribute (preferably equally) to generating the actuating force or torque. For example, in normal operation, a maximum rack force of 12 kN is required on the steering gear 4, so the actuators 12a, 12b each have to contribute a maximum of 6 kN. This corresponds, for example, to a load current of 100 A for each of the actuators 12a, 12b (for example, the RMS value of the three-phase alternating current) at a vehicle electrical system voltage of 12 V. The maximum load current for each of the control and supply units 11a, 11b in normal operation is therefore 100 A.

[0035] Figure 2 shows a possible circuit configuration of an inverter for one of the control and supply units 11 from Figure 1. Connections to the corresponding potentials of the DC electrical system are indicated by a plus sign and a minus sign at the top and bottom left of Figure 2. Three series circuits, each with two series-connected semiconductor switches 21, 22; 23, 24; 25, 26, are connected to these terminals, such that the positive and negative potentials of the electrical system are connected to the opposite ends of the series circuits. In the specific embodiment shown, the semiconductor switches 21, 22; 23, 24; 25, 26 are MOSFETs. Each of the semiconductor switches 21, 22; 23, 24; 25, 26 is a freewheeling diode 7 connected antiparallel, whereby the reference symbols 7 are only shown for the series circuit shown on the left.Between the two semiconductor switches 21, 22; 23, 24; 25, 26, each of the three series circuits has a connection for an electrical connection (phase line) 28, 29, 30 to the actuator 12, which is assigned to the control and supply unit 11. Due to the inverter's operating mode, known for normal operation, a three-phase alternating current is generated at the connection lines to the actuator 12, which supplies the actuator 12, designed as an electric motor (in particular an asynchronous motor), with electrical energy. Depending on the current of this load current, the actuator 12 generates the desired actuating force or torque. By adjusting the current, the control and supply unit 11 not only supplies the actuator 12 with electrical energy but also controls the actuating force or torque it generates.

[0036] Fig. 3 schematically shows an arrangement with a driver circuit 16 and one of the semiconductor switches 21 from Fig. 2. The electrodes or areas of the semiconductor switch 21 are shown, namely the control electrode (gate 13), drain 14, and source 15, which in this case is insulated. When the semiconductor switch 41 is switched on by electrically charging the gate 13 and thus setting a gate voltage relative to source 15, the load current flows via drain 14 to source 15. Of the two semiconductor switches 21, 22; 23, 24; 25, 26 connected in series in each of the series circuits, at most one of the semiconductor switches 21, 22; 23, 24; 25, 26 is switched on at any given time. Numerous measures are known from the operation of power converters, such as ensuring that the semiconductor switches 21, 22; 23, 24; 25, 26 can be avoided.However, it is also known that faults can occur which cause the series-arranged semiconductor switches 21, 22; 23, 24; 25, 26 to be switched on simultaneously, at least briefly. In particular, such a fault can lead to a failure of the power converter. The invention is particularly suitable for ensuring the operational safety of the vehicle in the event of such an initial fault.

[0037] In fault mode, the driver circuit 16 (described here as representative of all the inverter's driver circuits) repeatedly switches the semiconductor switch 21 it operates on the remaining functional control and supply unit as needed, such that a higher voltage is present at gate 13 relative to source 15 than occurs during normal operation. This causes the inverter to generate a higher load current when required, and the associated actuator to generate a higher actuating force or torque than occurs during normal operation.

[0038] For example, at vehicle speeds greater than 10 km / h, and with reference to the embodiment described above, a maximum load current of 100 A per actuator is required in fault operation, necessitating a maximum load current in the range of 120–160 A. This current can be generated briefly by appropriately increasing the voltage at gate 13 relative to source 15, for example, during a hazardous situation requiring a sudden evasive maneuver to avoid an obstacle (as an example of a driving maneuver with high lateral acceleration). A corresponding test for such an evasive maneuver is known as the moose test. In particular, the driving maneuver should therefore reliably enable a double lane change according to ISO 3888.

[0039] Prior to the figure description, numerous variations were already described, which can also be applied to the embodiments described with reference to the figures. List of reference symbols Actuator Freewheeling diode Control and supply unit actuator Gate Drain Source Driver circuit up to 26 semiconductor switches up to 30 phase lines

Claims

Patent claims 1. Actuating device (1) for a steering system of a vehicle, in particular a motor vehicle, wherein the actuating device (1) is designed to generate, depending on a steering input received from the driver or from an automatic steering device or steering assistance device of the vehicle, an actuating variable or a sum of actuating variables by which a steering angle of the steering system is set, the actuating device (1) comprises at least two mutually redundant control and supply units (11a, 11b) configured to each control and supply with electrical energy an associated actuator (12a, 12b) in order to adjust an actuating force or torque by means of the actuator by which the steering angle is adjusted, wherein each of the mutually redundant control and supply units (11a, 11b) is configured to generate or cause an associated contribution to the actuated variable or to the sum of the actuated variables, and For normal operation, in which at least two mutually redundant control and supply units (11a, 11b) and their respective associated actuators (12a, 12b) are functional, a maximum value for the contribution assigned to each of the control and supply units (11a, 11b) is defined, such that the sum of the contributions, in the case of maximum values, achieves a maximum required strength of the manipulated variable or a required maximum strength of the sum of the manipulated variables for normal operation. wherein the actuating device (1) is designed in a fault operation in which at least one of the at least two mutually redundant control and supply units (11a, 11b) is / are not functional with regard to providing its contribution and / or its contribution cannot be converted into an actuating force or an actuating torque, but in which at least one remaining control and supply unit (11) and the associated actuator (12) are functional to provide their contribution and convert it into an actuating force or actuating torque, to operate a remaining functioning control and supply unit (11) in such a way that it generates or causes a contribution to the control variable or to the sum of the control variables that is higher than the maximum value assigned to it, or to operate the remaining functioning control and supply facilities in such a way that they generate or cause a sum of contributions to the control variable or to the sum of the control variables that is higher than the sum of the maximum values ​​assigned to them.

2. Actuating device (1) according to claim 1, wherein the at least two mutually redundant control and supply units (11a, 11b) each have at least one power converter with a plurality of controllable semiconductor switches (21 to 26) which are repeatedly switched on and off during operation, so that an electrical load current is generated which is supplied to the associated actuator (12a, 12b) to adjust the steering angle, wherein the associated maximum value for normal operation is a maximum current value for the load current flowing through the controllable semiconductor switches (21 to 26) and wherein in fault operation a controller controls the controllable semiconductor switches (21 to 26) of at least one power converter of the remaining functional control and supply unit (11) in such a way that a higher load current than the maximum value assigned to it flows through the controllable semiconductor switches (21 to 26), or a controller controls the controllable semiconductor switches (21 to 26) of at least one of the remaining functional control and supply units in such a way that a higher load current than the maximum value assigned to at least one of the remaining functional control and supply units flows through these controllable semiconductor switches (21 to 26).

3. Actuating device (1) according to claim 2, wherein the controllable semiconductor switches (21 to 26) are voltage-controlled semiconductor switches (21 to 26) with respect to the magnitude of the load current and the control system controls control electrodes of the controllable semiconductor switches (21 to 26) in fault operation such that they are brought to a higher electrical voltage than in normal operation.

4. Steering system with an actuating device (1) according to one of claims 1 to 3, wherein the steering system is a steer-by-wire steering system.

5. Vehicle, in particular a motor vehicle, with a steering system comprising the actuating device (1) according to any one of claims 1 to 3.

6. Method for steering a vehicle, in particular a motor vehicle, wherein an actuating device (1) to generate, depending on a steering input received from the driver or from an automatic steering device or steering assistance device of the vehicle, an actuating variable or a sum of actuating variables by which a steering angle is set, the actuating device (1) comprises at least two mutually redundant control and supply units (11a, 11b), each of which controls and supplies with electrical energy an associated actuator (12a, 12b) in order to set an actuating force or torque by means of the actuator, by which the steering angle is set, wherein each of the mutually redundant control and supply units (11a, 11b) generates or causes an associated contribution to the actuated variable or to the sum of the actuated variables, and for normal operation in which the at least two mutually redundant control and supply units (11a, 11b) and each of the associated actuators (12a, 12b) are functional, an associated maximum value for the associated contribution is defined or is defined for each of the control and supply units (11a, 11b).so that, in the case of maximum values, the sum of the contributions achieves a maximum required strength of the manipulated variable or the required maximum strength of the sum of the manipulated variables for normal operation, wherein the actuating device (1) in a fault operation in which at least one of the at least two mutually redundant control and supply units (11a, 11b) is / are not functional with regard to providing its contribution and / or its contribution cannot be converted into an actuating force or torque, but in which at least one remaining control and supply unit (11) and the associated actuator (12) are functional, to provide its contribution and convert it into an actuating force or torque, the remaining control and supply unit (11) operates in such a way that it generates or causes a contribution to the control variable or to the sum of the control variables that is higher than the maximum value assigned to it, or operates the remaining control and supply units in such a way that they generate or cause a total sum of contributions to the control variable or to the sum of the control variables that is higher than the sum of the maximum values ​​assigned to them. 7.Method according to claim 6, wherein the at least two mutually redundant control and supply devices (11a, 11b) each have at least one power converter with a plurality of controllable semiconductor switches (21 to 26) which are repeatedly switched on and off during operation, so that an electrical load current is generated which is supplied to the associated actuator (12a, 12b) to adjust the steering angle, wherein the associated maximum value for normal operation is a maximum current value for the load current flowing through the controllable semiconductor switches (21 to 26) and wherein in fault operation. the controllable semiconductor switches (21 to 26) of at least one power converter of the remaining control and supply unit (11) are controlled in such a way that a stronger load current than the maximum value assigned to it flows through the controllable semiconductor switches (21 to 26), or the controllable semiconductor switches (21 to 26) of at least one of the remaining control and supply devices are controlled in such a way that a stronger load current flows through these controllable semiconductor switches (21 to 26) than the maximum value assigned to at least one of the remaining functional control and supply devices.

8. Method according to claim 6 or 7, wherein the at least two mutually redundant control and supply units (11a, 11b) each have at least one power converter with a plurality of controllable semiconductor switches (21 to 26) which are repeatedly switched on and off during operation, so that an electrical load current is generated which is supplied to the associated actuator (12a, 12b) to adjust the steering angle, wherein the associated maximum value for normal operation is a maximum current value for the load current flowing through the controllable semiconductor switches (21 to 26) and wherein in fault operation a controller controls the controllable semiconductor switches (21 to 26) of at least one power converter of the remaining functional control and supply unit (11) such that a higher load current than the maximum value assigned to it flows through the controllable semiconductor switches (21 to 26), or a controller controls the controllable semiconductor switches (21 to 26) of at least one of the remaining functional control and supply units such that a higher load current than the maximum value assigned to at least one of the remaining functional control and supply units flows through these controllable semiconductor switches (21 to 26).9.Method according to claim 7, wherein the controllable semiconductor switches (21 to 26) are voltage-controlled semiconductor switches (21 to 26) with respect to the magnitude of the load current and the control system controls control electrodes of the controllable semiconductor switches (21 to 26) in fault operation such that they are brought to a higher electrical voltage than in normal operation.

Images