Electronic steering system for vehicle and method for operating electronic steering system for vehicle

Abstract

The present invention relates generally to an electronic steering system (12) of a vehicle (10) and a method (50) of operating an electronic steering system (12) of a vehicle (10). The electronic steering system (12) includes at least one actuator (18, 32) having an electric motor (20, 34) and at least three converters (52) coupled to the electric motor (20, 34). The electric motor (20, 34) has at least two mutually independent windings (22). The first converter (52A) is coupled to a first winding (22A) of the electric motor (20, 34). A second converter (52B) is coupled to a second winding (22B) of the electric motor (20, 34). The third converter (52C) may be selectively coupled to both the first winding (22A) and / or the second winding (22B) or at least one additional third winding (22C) of the electric motor (20, 34). The converters (52) are configured such that the total maximum power output from all converters (52) to the electric motor (20, 34) is equal to a maximum of 133% nominal actuator power demand.

Description

TECHNICAL FIELD

[0001] The present disclosure relates generally to an electronic steering system of a vehicle and a method of operating an electric steering system of a vehicle. BACKGROUND

[0002] Electronic steering systems are an emerging steering technology that dispenses with the mechanical connection between the steering wheel and the wheels in favor of two actuators: one that generates torque to be fed back to the driver (at the steering wheel) and one that adjusts the wheels to the desired position.

[0003] Since a failure in the system can lead to a loss of steering capability, redundant systems are employed. Some approaches involve forced reduction of the vehicle speed in the event of a converter failure, although this reduces the functionality of the vehicle. Furthermore, forced reduction of the vehicle speed when a converter fails often shocks and disorients the driver.

[0004] Other approaches therefore include, for example, a control mechanism for controlling a redundant actuator having two sub-actuators, in particular an electric motor with two separate winding sets (cf. DE 102021112819 A1). The electric motor has a first actuator connection and a second actuator connection. A converter is coupled to each actuator connection. In the event of a failure of an actuator, an additional third converter can be coupled to the actuator connection, whereby the electric motor can continue to operate to output its maximum nominal torque, or at least a torque equivalent to the power of one converter if both converters fail. However, this follows the approach that the third converter has the same power capability as the first two converters. The electronic steering system is therefore both complex and expensive. Furthermore, the thermal load on the entire power supply circuit of the electric motor is also high.

[0005] EP3643583A1 and DE102018108597A1 disclose in this context that an electric motor can be operated with two mutually redundant converters. US2023 / 0013239A1, US2021 / 0276613A1 and US11780493B2 disclose steering systems with redundant component groups on the basis of which the steering system still has the possibility of reduced functionality (e.g. reduced maximum speed) after a failure. However, according to these approaches, only a single redundancy level is provided in the event of a converter failure, and a completely redundant component group means high costs.

[0006] There is therefore a need to overcome or at least alleviate the disadvantages of known approaches and electronic steering systems. In particular, there is a need to provide an approach and an electronic steering system that can guarantee multiple redundancies, but can reduce the complexity, costs and thermal load of the overall power supply circuit of the electric motor compared to previous approaches. SUMMARY

[0007] The subject matter of the independent claims achieves the above-mentioned objects. The dependent claims and the following description define advantageous embodiments, wherein each embodiment can represent an aspect of the present disclosure alone or in (sub-)combination with other embodiments. Some features are explained with respect to a method, other features are explained with respect to an apparatus. However, the relevant aspects can be applied to each other in an appropriate manner.

[0008] According to one aspect, some embodiments of the present disclosure relate to an electronic steering system for a vehicle. The electronic steering system comprises at least one actuator having an electric motor and at least three converters coupled to the electric motor. The electric motor has at least two winding sets independent from each other. A first converter is coupled to a first winding set of the electric motor. A second converter is coupled to a second winding set of the electric motor. A third converter can be selectively coupled to the first and / or second winding set or to at least one additional third winding set of the electric motor. The converters are configured such that the total maximum power output from all converters to the electric motor is equal to a maximum of 133% of a nominal actuator power demand.

[0009] The present disclosure is based on the finding that the third converter does not necessarily have the same power features as the first and second converters to guarantee a double redundancy for a continuous operation of the vehicle. Thus, an electronic steering system is provided which has a double redundancy in terms of the actuator, but which is less costly and allows for a reduced complexity compared to known approaches. In contrast to known approaches, it is not necessary that the third converter which facilitates the second level of redundancy has the same power parameters as the first and second converters as long as the first and second converters are configured such that they jointly guarantee a power capability of 100% of the electric motor. In other words, the third converter can advantageously be designed to have a power capability which is less than the first and second converters, i.e. to be able to output less electrical power than the first and second converters at maximum. Thus, the third converter can advantageously use less complex components, thereby reducing the cost of the electronic steering system. Optionally, all converters can be less complex if the power gain is distributed among all converters. Furthermore, the power reduction leads to a reduced thermal load of the circuitry for controlling the electric motor of the actuator compared to prior approaches. This advantageously prolongs the operational lifetime of the circuitry for controlling the electric motor of the actuator. Moreover, due to the reduced electrical output power of the third converter, installation space can be saved. Thus, the electronic steering system has many advantages compared to prior approaches, e.g. the steering system operates with high availability.

[0010] According to one aspect, some embodiments of the present disclosure also relate to a method for operating an electronic steering system of a vehicle. The electronic steering system comprises at least one actuator having an electric motor and at least three converters coupled to the electric motor. The electric motor has at least two winding sets independent from each other. A first converter is coupled to a first winding set of the electric motor. A second converter is coupled to a second winding set of the electric motor. The electronic steering system further has a third converter. The converters are configured such that the total maximum power output from all converters to the electric motor is equal to a maximum of 133% of a nominal actuator power demand. The method comprises at least the following steps:

[0011] - detecting a fault in the electronic steering system such that the converters can no longer be used; and

[0012] - selectively coupling the third converter to the first and / or second winding set or to at least one additional third winding set of the electric motor.

[0013] The method for operating the electronic steering system also achieves the advantages achieved by the electronic steering system described herein in a corresponding manner.

[0014] In the present case, an actuator is to be understood as meaning a component which transmits mechanical force to a driven component, for example a steering rack or a steering column. For this purpose, the actuator has an electric motor, the operation of which is controlled by an electronic control unit assigned to the relevant actuator.

[0015] The electronic control unit comprises at least one control logic unit and a power electronics unit assigned to the control logic unit. The power electronics unit is part of a converter, and the corresponding control logic unit is therefore assigned to the converter. The power electronics unit comprises a plurality of power switches, for example transistors.

[0016] Alternatively, a single control logic unit, which is usually composed of different electronic control units, can also be assigned to a plurality of individual power electronics units. For example, the control logic unit can be configured to control the switching states of at least two power electronics units having different sets of power switches.

[0017] The control logic unit usually comprises at least one data processing device and sensor devices, diagnostic circuits, communication devices and / or driver circuits which are relevant to the associated power electronics unit of the particular converter.

[0018] The actuator can optionally be a wheel actuator or a steering wheel actuator.

[0019] In some embodiments, the electronic steering system can also have two actuators, one wheel actuator and one steering wheel actuator, each with a suitable design and can be coupled to the three transducers assigned to the associated actuator. The functions of the electronic steering system described above can then be transferred accordingly to the two actuators.

[0020] If the actuator is a wheel actuator, it is preferably at least indirectly coupled to the steerable wheels of the vehicle. The wheel actuator does not have to be directly coupled to the steerable wheels of the vehicle. This means that the wheel actuator can also be coupled to the steerable wheels via further mechanical components, for example, the steering rack of the electronic steering system. A movement of the steering rack from the reference position (zero position) can cause the steerable wheels of the vehicle to deviate directly from the reference direction (straight-ahead direction).

[0021] If the actuator is a steering wheel actuator, it is optionally at least indirectly coupled to the steering wheel of the vehicle, for example, via the steering column to which the steering wheel is attached. A movement of the steering wheel actuator can then exert a torque on the steering column, which generates a torque on the steering wheel in order to provide the driver of the vehicle with torque feedback about the lateral guidance of the vehicle.

[0022] Each winding group can have a set of a plurality of individual windings, which are assigned to each other and to which different phase voltages can be applied in order to drive phase currents in the individual windings, in which these phase currents are formed. The winding groups are usually designed with respect to the stator. The rotor of the electric motor can thus be driven by the resulting phase currents. Finally, the electric motor can thus output a torque provided via the rotor to an external mechanical component, for example, to a pinion gear that interacts with the steering rack.

[0023] Other designs of winding groups and / or electric motors are also conceivable.

[0024] Generally, each transducer has a plurality of power switches, which can be controlled by the control logic unit in order to provide the winding groups with phase voltages.

[0025] Optionally, the winding groups of the electric motor can have the same design. This means that the winding groups can comprise the same number of windings.

[0026] In the present case, the maximum power output of a transducer is to be understood as meaning the maximum electrical power that a defined transducer can output, in particular in relation to the set of all windings of a winding group provided to the given transducer.

[0027] The nominal actuator power demand (nAPD) is to be understood as meaning the total electrical power demand that the electric motor must receive in all of its winding groups in order to output its nominal maximum torque at its output.

[0028] The limit values, for example, 133% nAPD, 66% nAPD or 33% nAPD (or other values described herein) should not be interpreted as being limited to the exact numerical values in each case. Each can optionally include a tolerance band of ± 5% points. On this basis, it can be assumed that 33% nAPD also includes 34% nAPD.

[0029] All power requirements discussed herein can be understood to mean the power requirement outputted over an electrical cycle of the electric motor control, i.e. the power requirement averaged over time in the electrical cycle. The different points in time during the electrical cycle here depend on the relative overlap between the rotor and the stator (for example, the rotor teeth relative to the stator teeth). By averaging over the electrical cycle, an average value of the relative overlap between the rotor and the stator over the entire electrical cycle can be determined.

[0030] Alternatively, in the present case, the power requirement can also be understood to mean the instantaneous power requirement at a defined point in time, i.e. the power requirement depending on the overlap between the rotor and the stator.

[0031] A fault in the electronic steering system can be a failure of the converter, the converter no longer being controlled so that it can be operated, or a power supply fault associated with the converter. Due to the various fault types of the electronic steering system, at least one converter is no longer available after a first fault (converter fault or power supply fault). In this case, the fault-free converter can guarantee the functionality of the electronic steering system.

[0032] It can also happen that, after the first fault, a further fault (second fault) associated with a further converter occurs, for example, a fault associated with one of the first and second converters which is still available after the first fault.

[0033] The converter is preferably configured and capable of being connected to the winding set in such a way that, in the event of a fault of the converter or a power supply fault, the electric motor can still be operated at least in a first fault mode in which the total power output from the fault-free converter to the electric motor is still equal to at least 66% of the nominal actuator power requirement (nAPD). Thus, even if the electronic steering system has a fault in relation to the converter of the associated actuator, the electric motor of the actuator can still generate sufficient torque in order to be able to continue to use the electronic steering system to operate the vehicle indefinitely. "Indefinitely" here means a potential time limit. In other words, if the remaining converter of the electric motor coupled to the associated actuator can still provide 66% nAPD, the electric motor can still output sufficient torque to the associated component (for example, a steerable wheel or a steering wheel), so that no (lasting) limitation of the functionality of the electronic steering system occurs.

[0034] In some embodiments, the converter is configured and capable of being connected to the winding sets in such a way that, in the event of a second fault in a further converter, or if there is only a first fault in the converter initially, in the event of a subsequent power supply failure, the electric motor can still be operated at least in a second fault mode in which the power output from the fault-free converter to the electric motor is still equal to at least 33% of the nAPD. This can enable the electronic steering system to continue to operate, bringing the vehicle into a suitable state. For example, this guarantees that the vehicle can still be operated with the electronic steering system in a certain fault mode despite two faults related to the converter or a combination of faults related to the converter and the power supply, which can be coupled to the same actuator. For example, the torque output by the electric motor to the relevant mechanical component, for example a steerable wheel or a steering wheel, is still sufficient to enable the vehicle to be steered in a crawl state.

[0035] For example, a configuration in which the electric motor can still be operated at 33% of the nAPD after two successive faults in different converters also ensures that a fault in the converter and a second fault in the converter or power supply, for example a supply circuit, still guarantees sufficient power for the electronic steering system so that it can still be operated in such a way that the vehicle is brought into a suitable state. On the other hand, as a rule, in response to a first fault, i.e. a fault in the power supply, for example a supply circuit, the vehicle is always immediately brought into a certain state, for example a crawl state. This likewise only requires that the electric motor can still be operated at least at 33% of the nAPD. This is because it cannot be guaranteed that, after a first fault in the power supply, for example a supply circuit, the subsequent fault is not a fault in a further power supply, for example an alternative supply circuit.

[0036] The third converter is preferably configured such that a maximum of 33% of the nAPD of each winding set of the electric motor can be output by the third converter to the associated winding set. This clearly shows that the third converter advantageously does not even have to guarantee 50% of the nAPD of the winding set. This means that the third converter can be more compact than the first and second converters, thereby reducing the cost of the electronic steering system, in particular compared to prior methods.

[0037] In some embodiments, the converter is configured and capable of being connected to the winding sets in such a way that each winding set of the electric motor can obtain a power output of a maximum of 50% of the nAPD. This can avoid having to design the winding sets of the electric motor for unnecessarily high power. Advantageously, this also leads to the electronic steering system being more compact in terms of the actuator.

[0038] Optionally, the third converter can be additionally selectively coupled to a fourth winding set of the electric motor. This guarantees an additional switching configuration of the converter group assigned to the actuator. Thereby, the versatility of the electric motor of the electronic steering system is increased.

[0039] Preferably, a separate control logic unit is assigned to each converter, wherein the plurality of control logic units are coupled to each other. Thus, the control logic unit of a converter assigned to a single actuator is also assigned to the actuator as a group. The coupling to each other simplifies the overall control of the group of control logic units.

[0040] Alternatively, a single shared control logic unit is assigned to all converters assigned to a common actuator. In other words, the single shared control logic unit of a group of converters assigned to a particular actuator can then guarantee control of all converters of the actuator. In this case, the electronic steering system is particularly compact.

[0041] In some embodiments, in the event of a failure of at least one converter or a power supply, a failure notification can be output to the driver of the vehicle. This can advantageously inform the driver of the vehicle of the failure. Thus, the driver will be informed that the electronic steering system should / must be checked.

[0042] Alternatively or additionally, in the event of a failure of at least one converter or a power supply, the maximum speed of the vehicle can be reduced. In this case, the electronic steering system can have at least one control logic unit which, due to the failure in the converter or the power supply failure, limits a higher level of driving functionality of the vehicle, i.e. the maximum speed that can be achieved. For this purpose, the control logic unit of the electronic steering system can be coupled to, for example, a high-level driving control device of the vehicle and can output a suitable control signal to the driving control device. The driving control device itself can have a suitably designed control logic unit.

[0043] In some embodiments, after detecting a failure in a converter or a power supply failure, the maximum speed of the vehicle can be limited to a speed equal to the crawl speed. This can guarantee to avoid an unintended driving state of the vehicle despite the failure in the converter.

[0044] The electric motor is preferably a 3n-phase, wherein n is greater than or equal to 1, preferably greater than 1. Each (electrical) phase of the electric motor is formed by a winding of a winding group. Each winding group can comprise three windings. Thus, the electric motor has at least one winding group, preferably two winding groups. But optionally also more winding groups, for example three or four, are possible. This increases the versatility of the electronic steering system.

[0045] Generally, each converter and each individual power electronics unit of a converter, e.g. for converters having multiple power electronics units, is coupled to a separate winding set of the electric motor. However, alternatively, different converters can be coupled to the same (single) winding set of the electric motor. In this case, the electric motor itself does not guarantee any redundancy, but the different converters / power stages still guarantee at least a redundancy of the control winding set. Since electric motors rarely fail, this configuration is also acceptable. In this case, the electric motor can also simply have three phases, thereby reducing the manufacturing costs.

[0046] In some embodiments, at least the third converter can be coupled to two different power supply circuits of the vehicle to supply electric power. This guarantees a redundancy of the third converter with respect to different power supply circuits of the vehicle, thereby increasing the availability of the third converter. For example, a failure event in which a particular power supply circuit fails can be avoided, since the third converter can still be coupled to a further power supply circuit.

[0047] A failure in a converter is not limited to a complete failure of the converter. For example, a component of the converter can also be defective, resulting in the converter no longer being reliably operable. For example, the converter has multiple power switches, one of which can be defective. Furthermore, a failure in a converter can also be that the converter does not operate in the intended manner. For example, the converter can provide an output signal that is outside the intended parameter range. In this case, it can be assumed that the converter can no longer be operated normally.

[0048] In a further alternative, a failure in a converter can also be that the control logic unit coupled to the converter is defective and can no longer be used to control the converter such that the converter provides the required output signal.

[0049] Furthermore, a failure in the electronic steering system can also be a failure of a power supply circuit of the vehicle. Generally, the first converter assigned to the actuator is coupled to a first power supply circuit. On the other hand, the second converter assigned to the actuator is coupled to a second power supply circuit. The third converter assigned to the actuator can be selectively coupled to the first and second power supply circuits. Thus, although a failure in one of the power supply circuits results in the first or second converter no longer being available, the third converter, because it can be coupled to both power supply circuits, can still be used to operate the electric motor of the actuator according to the first failure mode.

[0050] The electronic steering system can have at least one sensor which can be used to detect a failure in a converter (or a control logic unit coupled thereto) or a power supply failure. As a result of the failure detection, the sensor can pass a suitable signal to a control logic unit of the electronic steering system or a control logic unit coupled to the electronic steering system, e.g. to a higher-level drive control device of the vehicle.

[0051] The method is optionally in the form of a computer-implemented method. This means that the method steps can be executed with the aid of one or more data processing devices. In particular, the data processing devices can initiate or execute the respective steps. For example, a data processing device of a control logic unit of an electronic steering system can detect a fault or a power failure in the first and / or second control logic unit and selectively couple the third control logic unit to at least one additional third winding group of the first and / or second winding group or electric motor.

[0052] According to a further aspect, the disclosure also relates to a computer program product comprising commands which, when the program is executed by a computer, cause it to carry out the method described herein. The advantages achieved by the method described herein are also achieved in a corresponding manner by the computer program product.

[0053] According to a further aspect, the disclosure also relates to a computer-readable storage medium comprising commands which, when the program is executed by a computer, cause it to carry out the method described herein. The advantages achieved by the method described herein are also achieved in a corresponding manner by the computer-readable storage medium.

[0054] According to a further aspect, some embodiments of the disclosure also relate to a vehicle having an electronic steering system. The advantages achieved by the method described herein are also achieved in a corresponding manner by the vehicle.

[0055] Within the meaning of the present disclosure, a vehicle can in particular comprise a land-based vehicle, i.e. an off-road vehicle and a road vehicle, such as a passenger car, a bus, a truck and other utility vehicles. The vehicle can be manned or driverless. The vehicle can be at least partially electrically driven, have an internal combustion engine and / or an electric motor as a drive.

[0056] All features explained with regard to the different aspects can be combined individually or in combination with other aspects (sub-) combinations. BRIEF DESCRIPTION OF DRAWINGS

[0057] The present disclosure and further advantageous embodiments and developments thereof are described and explained in more detail below with reference to the examples shown in the drawings, in which:

[0058] Figure 1 A simplified schematic diagram of a vehicle having an electronic steering system is shown according to an embodiment;

[0059] Figure 2 A simplified schematic diagram of a method of operating a vehicle having an electronic steering system is shown; and

[0060] Figures 3 to 8 A simplified schematic diagram of an actuator of an electronic steering system is shown according to various embodiments. DETAILED DESCRIPTION

[0061] The detailed description set forth below in connection with the appended drawings, where like numerals designate like elements, is intended as a description of various embodiments of the disclosed subject matter and is not intended to represent the only embodiments in which the disclosed subject matter can be practiced. Each embodiment described in this disclosure is intended to serve only as an example or illustration of the disclosed subject matter and is not intended to be construed as superior or inferior in any way to other embodiments. The illustrative examples contained herein utilize exemplary language but do not pose a limitation on the scope of the subject matter disclosed. The scope of the subject matter disclosed is defined only by the appended claims, the description being intended as a non-limiting example in connection with the disclosure. Numerous modifications to the described embodiments will be apparent to those skilled in the art, and the generality of the described principles can be applied to other embodiments and applications without departing from the spirit and scope of the described embodiments. Therefore, the described embodiments are not to be limited to the embodiments shown but are to be accorded the full scope consistent with the principles and features disclosed herein.

[0062] All features disclosed in the specification, the claims, and the drawings can be combined in any combination, except combinations that are clearly not feasible.

[0063] For the purposes of this disclosure, the phrase "at least one of A, B, and C" means, for example, (A), (B), (C), (A and B), (A and C), (B and C), or (A, B, and C), including all further possible combinations of the elements, if more than three elements are specified. In other words, the expression "at least one of A and B" means "A and / or B", i.e. either "A" alone, "B" alone, or "A and B".

[0064] Figure 1 A simplified schematic of a vehicle 10 with an electronic steering system 12 is shown according to an embodiment.

[0065] The vehicle 10 further comprises steerable wheels 14. The steerable wheels 14 are coupled to a common steering rack 16. The common steering rack 16 can be moved out of a reference position, e.g. a zero position, resulting in a steering motion of the steerable wheels 14. Thus, for example, the steerable wheels 14 can be deflected from a straight ahead direction of the vehicle 10 such that the vehicle 10 turns. Thus, during deflection, the steerable wheels 14 have different wheel angles, e.g. based on the motion of the steering rack 16.

[0066] While only front wheel steering is shown here, the vehicle 10 can optionally or additionally also have a correspondingly designed rear wheel steering, as is generally apparent.

[0067] The electronic steering system 12 has a wheel actuator 18 in order to move the steering rack 16. In the present case, the wheel actuator 18 is coupled to the steering rack 16. Alternatively, the wheel actuator 18 can also be coupled in another way to the steerable wheel 14 in order to be able to influence its orientation (wheel angle).

[0068] According to the present embodiment, the wheel actuator 18 has an electric motor 20. The electric motor 20 has at least two winding groups 22, each winding group comprising a set of windings. Each winding group 22 is configured such that, when a power supply signal, such as a phase voltage, is applied, a phase current for driving a rotor of the electric motor 20 is established in the underlying windings. The rotor can then be coupled to the steering rack 16, thereby facilitating movement of the steering rack 16.

[0069] Generally, the electric motor 20 can have more than two winding groups 22.

[0070] Generally, each winding group 22 is three-phase, so that, in the present case, the electric motor 20 likewise has a 3n-phase design, with n = 2, i.e. 6-phase. However, since the electric motor 20 can also have additional winding groups 22, n can also be greater than 2, for example 3 or 4. The electric motor 20 is then 9-phase or 12-phase accordingly.

[0071] The wheel actuator 18 also has at least one wheel sensor 24. Generally, a plurality of wheel sensors 24 can also be provided. The wheel sensor 24 is configured to detect a position and / or movement of the steerable wheel 14 or of a component coupled thereto, here the steering rack 16. By detecting the position of the steering rack 16, the wheel angle of the steerable wheel 14 can be determined. The orientation of the steerable wheel 14 can thus be determined.

[0072] While the wheel sensor 24 is designed herein as part of the wheel actuator 18, the wheel sensor 24 can also optionally be positioned separately from the wheel actuator 18, but still be configured to detect a position and / or movement of the steerable wheel 14 of the vehicle or of a component coupled thereto. For example, the wheel sensor 24 can be coupled to the steering rack 16 separately from the wheel actuator 18.

[0073] The electronic steering system 12 of the vehicle 10 also has a steering wheel 30. Using the steering wheel 30, a driver of the vehicle 10 can issue steering instructions for the vehicle 10 in order to steer the vehicle 10 in a desired direction.

[0074] The steering wheel actuator 32 of the electronic steering system 12 is coupled to the steering wheel 30. The steering wheel actuator 32 has a further electric motor 34. The electric motor 34 of the steering wheel actuator 32 likewise comprises two winding sets 22. In general, the electric motor 34 can also have a plurality of winding sets 22. The winding sets 22 of the electric motor 34 of the steering wheel actuator 32 are configured to work in a corresponding manner to the winding sets 22 of the electric motor 20 of the wheel actuator 18. This means that the winding sets 22 of the electric motor 34 are configured to drive a rotor of the electric motor 34. As a result, the electric motor 34 can apply a torque to the steering wheel 30 of the vehicle 10, which constitutes a feedback torque of the driver in order to give the driver a feeling of lateral guidance of the vehicle 10.

[0075] Of course, the winding sets 22 of the electric motors 20, 34 can differ in size.

[0076] In the present case, the electric motor 34 of the steering wheel actuator 32 has two winding sets 22 and is therefore 6-phase.

[0077] The electronic steering system 12 also has a steering wheel sensor 36, which is part of the steering wheel actuator 32. In general, a larger number of steering wheel sensors 36 can also be provided. The steering wheel sensor 36 is configured to detect steering instructions of the driver on the basis of a steering wheel angle of the steering wheel 30 or of a component coupled thereto, for example a steering column, relative to a reference position.

[0078] Alternatively, the steering wheel sensor 36 can also be separate from the steering wheel actuator 32, but is still configured to detect a position and / or a movement of the steering wheel 30 of the vehicle 10 or of a component coupled thereto.

[0079] In the present case, the electronic steering system 12 of the vehicle 10 comprises a control logic unit 42. The control logic unit 42 has at least one data processing device 44 and is coupled to the wheel actuator 18, the wheel sensor 24, the steering wheel actuator 32 and the steering wheel sensor 36.

[0080] In general, the electronic steering system 12 can also have separate control logic units 42, one assigned to the wheel actuator 18 and one assigned to the steering wheel actuator 32. In the present case, however, the control functions are combined in a single control logic unit 42.

[0081] Furthermore, according to the present embodiment, the electronic steering system 12 has an advanced driving control device 46 and an output device 48, which are both coupled to the control logic unit 42.

[0082] The advanced driving control device 46 is used for driving the vehicle 10. The advanced driving control device 46 is configured to receive a control signal from the control logic unit 42 and, as a result of the control signal, to reduce a maximum speed achievable by the vehicle 10.

[0083] Optionally, the higher-level driving control device 46 can be configured to ensure overall vehicle control, i.e. control of the vehicle 10 in terms of the vehicle longitudinal axis, the vehicle lateral axis and the vehicle vertical axis. To this end, the higher-level driving control device 46 can then output corresponding control signals to the control logic unit 42.

[0084] The output device 48 is configured to output a notification to the driver of the vehicle 10, for example regarding a fault in the electronic steering system 12. To this end, the output device 48 can receive corresponding control signals from the control logic unit 42.

[0085] The control logic unit 42 serves as a link between the wheel actuator 18 and the steering wheel actuator 32 in order to, on the one hand, generate a change in the wheel angle of the steerable wheels 14 of the vehicle 10 depending on steering instructions by the driver via the steering wheel 30 and, on the other hand, to ensure torque feedback to the driver of the vehicle 10 at the steering wheel 30 based on the change in the wheel angle of the steerable wheels 14.

[0086] Optionally, different control logic units 42A, 42B (see Figure 1 ) can be provided. The first control logic unit 42A is then assigned to the wheel actuator 18. The second control logic unit 42B is assigned to the steering wheel actuator 32 separately from the first control logic unit 42A. In this case, the respective control logic units 42 can also be spatially separated from one another. For the sake of simplicity, the different control logic units 42A, 42B are combined here into one common control logic unit 42.

[0087] In the present case, the control logic unit 42 is also configured to detect a fault within the electronic steering system 12 or a power supply fault of a power supply circuit coupled to the electronic steering system 12. Optionally, the fault detection can also be performed by the higher-level driving control device 46. As a result of the fault detection, the control logic unit 42 of the electronic steering system 12 can output control signals to the higher-level driving control device 46 and / or the output device 48 in order to reduce the maximum speed achievable by the vehicle 10 and / or to output a notification to the driver regarding the fault occurring in the electronic steering system 12.

[0088] Each electric motor 20, 34 is coupled to a corresponding converter, which provides a phase voltage or a phase current for the winding set 22 of the electric motor 20, 34. This will be explained in detail with reference to Figures 3 to 8 .

[0089] Figure 2 A simplified schematic of a method 50 for operating a vehicle 10 having an electronic steering system 12 is shown. Optional steps are shown in dashed lines.

[0090] With regard to the method 50,Figures 3 to 8 A simplified schematic of an actuator 18, 32 of an electronic steering system 12 according to various embodiments is shown.

[0091] The actuator 18, 32 comprises an electric motor 20, 34. According to this embodiment Figure 3 ), the electric motor 20, 34 has two winding sets 22 and is thus 6-phase.

[0092] The actuator 18, 32 comprises a plurality of transducers 52 which are assigned to the electric motor 20, 34. Each transducer 52 is configured to provide a phase voltage for application to the windings of a winding set 22 of the electric motor 20, 34.

[0093] According to this embodiment, a first transducer 52A is coupled to a first winding set 22A of the electric motor 20, 34. According to this embodiment, a second transducer 52B is coupled to a second winding set 22B of the electric motor 20, 34. Furthermore, the actuator 18, 32 of the electronic steering system 12 has a third transducer 52C which can be selectively coupled to both the first winding set 22A and / or the second winding set 22B. According to this embodiment, for this purpose, the third transducer 52C has two mutually independent power electronics units 54, 54A, 54B, one of which is coupled to the first winding set 22A of the electric motor 20, 34 and the other of which is coupled to the second winding set 22B of the electric motor 20, 34.

[0094] Furthermore, the actuator 18, 32 of the electronic steering system 12 is coupled to two external power supply circuits 56, 56A, 56B for the supply of electrical power. According to this embodiment, the first transducer 52A and the third transducer 52C are coupled to a first power supply circuit 56A. Furthermore, the second transducer 52B and the third transducer 52C are coupled to a second power supply circuit 56B. This means that the third transducer 52C is coupled to both power supply circuits 56A, 56B. The first power electronics unit 54A of the third transducer 52C is directly coupled to the first power supply circuit 56A. The second power electronics unit 54B of the third transducer 52C is directly coupled to the second power supply circuit 56B. The control logic unit 42 of the third transducer 52C is operated by the first power supply circuit 56A and the second power supply circuit 56B, for example, via a circuit comprising a diode 59.

[0095] The converters 52 generally have a plurality of power switches, the switching arrangement of which is defined by control signals indirectly provided by the control logic unit 42 coupled to the respective converter 52 (e.g. via a pulse width modulator and / or gate driver circuit). According to this embodiment, the converters 52 are coupled to a single shared control logic unit 42 of the electronic steering system 12. However, in general, each converter 52 can also be assigned a separate control logic unit 42, thereby further increasing the redundancy of the actuators 18, 32 and thus of the electronic steering system 12.

[0096] According to this embodiment, both the first converter 52A and the second converter 52B are configured to be able to supply the respective winding set 22 of the electric motor 20, 34 with an electrical power equal to 50% of the nominal actuator power demand (nAPD), i.e. the power demand the electric motor 20, 34 has to receive in order to output a nominal maximum torque at its output, e.g. to an external mechanical component coupled to the electric motor 20, 34 (e.g. the steering rack 16 or the steering wheel 30).

[0097] In the present case, the third converter 52C is configured such that it can use either the first power electronics unit 54A or the second power electronics unit 54B in order to output a total of 33% of the nAPD to one of the winding sets 22 of the electric motor 20, 34. This means that the third converter 52C is more compact in terms of its power output than the first converter 52A and the second converter 52B. As a result, the actuators 18, 32 and thus the electronic steering system 12 are compact.

[0098] In the following exemplary discussion with respect to faults and in relation to the embodiments of the present disclosure, the fault occurring refers to the first converter 52A and / or the first power supply circuit 56A. Of course, a fault can also occur on the second converter 52B or the second power supply circuit 56B. Accordingly, a fault can also occur on the third converter 52C if the third converter 52C is already coupled to the electric motor 20, 34. These explanations can then be applied accordingly. Furthermore, the second fault refers to a fault related to the second converter 52B or, if no power supply fault has occurred before, to the first fault (power supply fault) in the power supply circuit 56A, 56B. Of course, a fault can also occur on the third converter 52C. These explanations can then be applied accordingly.

[0099] In a normal mode of operation of the actuators 18, 32, the first converter 52A and the second converter 52B are coupled to the respective winding set 22 of the electric motor 20, 34. Then, the converters 52 jointly provide 100% of the nAPD to the electric motor 20, 34.

[0100] If a fault now occurs with respect to the first converter 52A or a power failure with respect to the first supply circuit 56A, the power electronics unit 54B of the third converter 52C can be supplied by the second supply circuit 56B. Figure 2 ) includes a step S1 in which a fault in the electronic steering system 12 is detected, the type of which makes the converter 52 (here, the first converter 52A) no longer usable. Furthermore, the method 50 includes a subsequent step S2 in which the third converter 52C selectively controls and supplies power to the first winding set 22A of the electric motor 20, 34.

[0101] As a result of the fault associated with the first converter 52A, according to the first fault mode, the electric motor 20, 34 can be used with the aid of the second winding set 22B, which is still supplied with 50% of the nAPD by the second converter 52B, and with the aid of the first winding set 22A, which is still supplied with 33% of the nAPD by the first power electronics unit 54A of the third converter 52C. Figure 3 ), in the first fault mode, the electric motors 20, 34 are still supplied with 83% of nAPD. Therefore, the method 50 includes a subsequent optional step S3, in which, in the event of a first fault in the converter 52A, the electric motors 20, 34 can still be operated at least in the first fault mode, in which the total power output from the fault-free converters 52B, 52C to the electric motors 20, 34 is still equal to at least 66% of nAPD, i.e., greater than or equal to 66% (here, in particular 83%). This is still sufficient to be able to permanently operate the electric motors 20, 34 of the actuators 18, 32.

[0102] If a subsequent failure related to the second converter 52B also occurs, or if the first failure is a failure in a converter 52, e.g. in the first converter 52A, and a subsequent power supply failure related to the power supply circuit 56A, 56B, e.g. the second power supply circuit 56B, occurs, the electric motor 20, 34 can be operated in a second failure mode based on the first winding set 22A and the coupling to the first power electronics unit 54A, at least still having 33% of the nAPD, i.e. more than or equal to 33% of the nAPD. In contrast, if the third converter 52C fails, the second winding set 22B of the electric motor 20, 34 can still be supplied with 50% of the nAPD by the second converter 52B (in the absence of a power supply failure related to the second power supply circuit 56B). Thus, the method 50 comprises a subsequent optional step S4, in which, in the event of a second (subsequent) failure in the converter 52B, the electric motor 20, 34 can at least still be operated in a second failure mode in which the power output from the fault-free converter 52C to the electric motor 20, 34 still equals at least 33% of the nAPD, i.e. more than or equal to 33% of the nAPD. The power output in the second failure mode is sufficient for the electric motor 20, 34 of the actuator 18, 32 to at least still be operated at a reduced power parameter, so that the driver of the vehicle 10 can steer the vehicle 10 to a suitable parking position.

[0103] The connection of the converters 52 to the winding sets 22 of the electric motor 20, 34 ensures that at no time more than 50% of the nAPD supplied to the winding sets of the electric motor 20, 34 is exceeded (regardless of the failure mode). This also means that the electric motor 20, 34 and the actuator 18, 32 can be compact.

[0104] Furthermore, the method 50 can be extended by optional steps S5 and S6. Corresponding to the optional step S5, the control logic unit 42 of the electronic steering system 12 outputs a notification to the driver of the vehicle 10, e.g. by means of the output device 48, if a failure in a converter 52 or a power supply failure occurs (step S5). This can increase the information value for the driver of the vehicle 10, so that the driver of the vehicle 10 can check the electronic steering system 12.

[0105] Alternatively or additionally, the method 50 can also comprise an optimal step S6 in which the maximum speed achievable by the vehicle 10 is reduced. For this purpose, the control logic unit 42 of the electronic steering system 12 can output an appropriate control signal, e.g. to a higher-level driving control device 46 of the vehicle 10, which controls the driving of the vehicle 10.

[0106] The steps S5 and / or S6 can be initiated as a result of the steps S2, S3 and / or S4.

[0107] Although the failure detection with respect to the converter 52 and the power supply circuit 56 is explained in the present case with reference to the control logic unit 42 of the electronic steering system 12, the failure detection and the measures initiation can generally also be performed by a control logic unit of the vehicle 10 external to the electronic steering system 12, for example, a higher-ranking drive control device 46.

[0108] The arrangement of the converters 52 and the selective coupling of the third converter 52C to the winding set 22 of the electric motor 20, 34 ensures a high availability of the actuators 18, 32 of the electronic steering system 12. This increases the functionality of the electronic steering system 12 compared to prior approaches, while the third converter 52C can advantageously be more compact than the first converter 52A and the second converter 52B in terms of its power output. Thus, the electronic steering system 12 is less costly than prior approaches.

[0109] With respect to further embodiments of the actuators 18, 32 of the electronic steering system 12 Figure 4 to 8 , only the differences are discussed here.

[0110] According to Figure 4 the embodiments of the actuators 18, 32, the switching device 58 for coupling the third converter 52C to the different power supply circuits 56A, 56B is located external to the third converter 52C. For example, the switching device 58 can also be part of the control logic unit, for example, the control logic unit 42 of the electronic steering system 12. The switching device 58 can be configured to selectively switch back and forth between the power supply circuits 56A, 56B. Alternatively, the switching device 58 can also be configured to combine the two power supply circuits 56A, 56B, for example, by means of a diode circuit (logic circuit). The switching device 58 can be an external component, but can also be part of the third converter 52C.

[0111] Furthermore, the first power electronics unit 54A and the second power electronics unit 54B of the third converter 52C are configured such that they can each only output 16% of the nAPD to the winding set 22 of the electric motor 20, 34.

[0112] In a first failure mode (failure in the converter 52A or the power supply circuit 56A), the second winding set 22B of the electric motor 20, 34 is still supplied with 50% of the nAPD by the second converter 52B. Furthermore, the first winding set 22A of the electric motor 20, 34 is supplied with 16% of the nAPD by the first power electronics unit 54A of the third converter 52C. Thus, in the first failure mode, the total power output of the non-failed converters 52 is equal to 66% of the nAPD.

[0113] If the second converter 52B also fails, each of the windings 22A, 22B of the electric motor 20, 34 can still be supplied with 16% of nAPD by the two power electronics units 54A, 54B of the third converter 52C. If the third converter fails, the second winding 22B can at least still be supplied with 50% of nAPD by the second converter 52B. Thus, in the second failure mode, the total power output of the third converter 52C equals at least 33% of nAPD.

[0114] As in the case of the previous embodiments, in the event of a loss of the supply circuit 56A, 56B, at least 66% of nAPD (power supply failure is the first failure) or at least 33% of nAPD (power supply failure is the second failure after the initial failure in the converter 52) are still available.

[0115] Figure 5 The embodiments of the actuator 18, 32 in Figure 4 correspond essentially to the embodiments of the actuator 18, 32 in Figure 4 However, the first and second converters each have a compact configuration such that they each have a maximum power output of 33% of nAPD. This further reduces the cost of the actuator 18, 32 and thus of the electronic steering system 12. Furthermore, unlike the exemplary embodiments of

[0116] In normal operation mode (all converters 52 and supply circuits 56 are fault-free), all converters 52 are coupled to the windings 22 of the electric motor 20, 34. The first winding set 22A of the electric motor 20, 34 is supplied with 33% of the nAPD by the first converter 52A and additionally with a part of the nAPD by the first power electronics unit 54A of the third converter 52C. The second winding set 22B of the electric motor 20, 34 is supplied with 33% of the nAPD by the second converter 52B and additionally with a part of the nAPD by the second power electronics unit 54B of the third converter 52C. The third converter 52C is configured to guarantee that a maximum of 50% of the nAPD is supplied to each winding set 22 of the electric motor 20, 34. For example, the third converter 52C can be controlled accordingly by the control logic unit 42. This means that in normal operation mode of the electric motor 20, 33 all converters 52 are coupled to the electric motor 20, 33. Of course, alternatively, the required power can be freely distributed differently between the first converter 52A and the first power electronics unit 54A or between the second converter 52B and the second power electronics unit 54B, as long as each winding set 22 of the electric motor 20, 34 is supplied with a maximum of 50% of the nAPD in total when the nAPD demand is maximum.

[0117] In the first fault mode, the second winding set 22B is supplied with 33% of the nAPD by the second converter 52B and the first winding set 22A is supplied with 33% of the nAPD by the third converter 52C. In the second fault mode, the third converter 52C is still configured to provide 33% of the nAPD for at least one winding set 22 of the electric motor 20, 34. Conversely, if the third converter 52C fails, the second converter 52B can still provide 33% of the nAPD for the second winding set 22B.

[0118] As in the case of the previous embodiments, in the event of a loss of the supply circuits 56A, 56B, at least 66% of the nAPD (power supply failure as first fault) or at least 33% of the nAPD (power supply failure as second fault after an initial failure in the converter 52) is still available.

[0119] Figure 6 The embodiments of the actuator 18, 32 in Figure 4embodiment. However, each of the first and second converters has a compact configuration so that each has a maximum power output of 33% of nAPD. This further reduces the cost of the actuators 18, 32, and thereby the cost of the electronic steering system 12. In the first fault mode, the second winding set 22B is supplied with 33% of nAPD by the second converter 52B, and is additionally supplied with 16% of nAPD by the third converter 52C. Furthermore, the first winding set 22A is supplied with 16% of nAPD by the third converter 52C. The total power output of the fault-free converter 52 is then equal to 66% of nAPD. In the second fault mode, the third converter 52C is still configured to provide 16% of nAPD to each of the two winding sets 22 of the electric motor 20, 34. Conversely, if the third converter 52C fails, the second converter 52B can still provide 33% of nAPD to the second winding set 22B.

[0120] As with the previous embodiments, in the event of a loss of power supply circuits 56A, 56B, at least 66% of nAPD (power failure is the first fault) or at least 33% of nAPD (power failure is the second fault after the initial fault in converter 52) is still available.

[0121] Figure 7 The embodiment of the actuators 18, 32 in the embodiment corresponds essentially to Figure 5 However, in the present case, the electric motors 20, 34 have four winding sets 22 and are therefore 12-phase. The converter 52 is configured for direct power supply.

[0122] In the normal mode of operation of the electric motor 20, 34, all converters 52 are in operation. The first winding group 22A of the electric motor 20, 34 is supplied with a portion of nAPD by the first converter 52A. The second winding group 22B of the electric motor 20, 34 is supplied with a portion of nAPD by the second converter 52B. The third and fourth winding groups 22C, 22D are each supplied with a portion of nAPD by the power electronics unit 54A, 54B of the third converter 52C. However, the third converter 52C is configured such that a maximum of 33% of nAPD is output to the electric motor 20, 34. The converters 52 are additionally configured such that each converter can output a maximum of 33% of nAPD to a winding group 22 of the electric motor 20, 34. The converters 52 are further configured such that the total (active) power output from the converters 52 is a maximum of 100% of nAPD. For example, the control logic unit 42 can perform the respective control. This means that, in the normal mode of operation of the electric motor 20, 34, the third converter 52C supplies only one winding group 22 of the electric motor 20, 33 with 33% of nAPD power, or supplies the third and fourth winding groups 22C, 22D with a total power output from the third converter 52C which is equal to 33% of nAPD.

[0123] Alternatively, of course, the required power can be freely distributed differently between the first converter 52A and the first power electronics unit 54A or between the second converter 52B and the second power electronics unit 54B, as long as a total of 100% of nAPD is reached when the nAPD demand is maximum, and the power electronics units 54 each output no more than 33% of nAPD. Since, in the case of an even distribution between the power electronics units 54 (converters 52), only 75% of the maximum nominal power is used to guarantee 100% of nAPD, the load on the components is less. In particular, this can reduce the thermal load, thus prolonging the operating life.

[0124] In the first fault mode, the second winding group 22B is supplied with 33% of nAPD by the second converter 52B, and the third or fourth winding group 22C, 22D is supplied with 33% of nAPD by the first or second power electronics unit 54A, 54B of the third converter 52C. If the third converter 52C fails, in the first fault mode the first winding group 22A and the second winding group 22B are each supplied with 33% of nAPD by the first converter 52A and the second converter 52B. The total power output of the fault-free converters 52 is therefore equal to at least 66% of nAPD.

[0125] In the second failure mode, at least one winding set 22 can still be supplied with 33% of nAPD by the converter 52. If the first converter 52A and the second converter 52B fail, the third converter 52C can still always output 33% of nAPD to the winding set 22 of the electric motor 20, 34.

[0126] As in the case of the previous embodiment, in the event of a loss of the supply circuit 56A, 56B, at least 66% of nAPD (power failure as first failure) or at least 33% of nAPD (power failure as second failure after an initial failure in the converter 52) is still available.

[0127] Figure 8 The embodiment of the actuator 18, 32 in Figure 6 corresponds essentially to the embodiment in . However, the first and second converter each have a compact configuration such that they each have a maximum power output of 33% of nAPD. This further reduces the cost of the actuator 18, 32 and thus of the electronic steering system 12. Furthermore, the third converter has only one power electronics unit 54, which is coupled to the third winding set 22C of the electric motor 20, 34. The electric motor 20, 34 thus has a 9-phase design.

[0128] In the first failure mode, the second winding set 22B is supplied with 33% of nAPD by the second converter 52B and additionally with 33% of nAPD by the third converter 52C. The total power output of the fault-free converter 52 then amounts to 66% of nAPD. In the second failure mode, the third converter 52C is still configured to provide 33% of nAPD to the winding set 22C of the electric motor 20, 34. Conversely, if the third converter 52C fails, the second converter 52B can still provide 33% of nAPD for the second winding set 22B.

[0129] As in the case of the previous embodiment, in the event of a loss of the supply circuit 56A, 56B, at least 66% of nAPD (power failure as first failure) or at least 33% of nAPD (power failure as second failure after an initial failure in the converter 52) is still available.

[0130] The actuator 18, 32 can thus be implemented in many different ways. This increases the versatility of the electronic steering system 12. These advantages can be achieved even though the third converter 52C can advantageously be very compact.

[0131] The detailed description disclosed herein uses circuitry (e.g., one or more circuits) to implement the standards, protocols, methods, or techniques disclosed herein to operably couple two or more components to generate information, process information, analyze information, generate signals, encode / decode signals, convert signals, transmit and / or receive signals, control other devices, etc. Any type of circuitry can be used.

[0132] In one embodiment, the circuitry, such as the control device, includes, among other things, one or more data processing apparatus, such as a processor (e.g., a microprocessor), a central processing unit (CPU), a digital signal processor (DSP), an application-specific integrated circuit (ASIC), a field programmable gate array (FPGA), a system-on-chip (SoC), etc., or any combination thereof, and can include discrete digital or analog circuit elements or electronics, or combinations thereof. In one embodiment, the circuitry includes a hardware circuit implementation (e.g., an implementation in analog circuitry, an implementation in digital circuitry, etc., and combinations thereof).

[0133] In one embodiment, the circuitry includes a combination of circuitry and a computer program product that contains software instructions or firmware instructions that are stored on one or more computer readable storage devices and interact to cause a device to perform one or more of the protocols, methods, or techniques described herein. In one embodiment, the circuitry technology includes circuitry that requires software, firmware, etc., to operate, such as, for example, a microprocessor or portions of a microprocessor. In one embodiment, the circuitry includes one or more processors or portions thereof, and associated software, firmware, hardware, etc.

[0134] In the present disclosure, reference can be made to quantities and numbers. Unless explicitly stated, these quantities and numbers should not be considered limiting but as examples of quantities or numbers possible in the context of the present disclosure. In this regard, the term “a plurality of” can also be used in the present disclosure to refer to a quantity or number. In this regard, the term “a plurality of” refers to any number greater than one, such as, for example, two, three, four, five, etc. The terms “about,” “approximately,” “nearly,” and the like mean plus or minus 5% of the stated value.

[0135] While the present disclosure has been presented and described with reference to one or more embodiments, those skilled in the art will be able to make equivalent changes and modifications to the present disclosure after reading and understanding the description and the accompanying drawings.

Claims

1. An electronic steering system (12) for a vehicle (10), comprising at least one actuator (18, 32) with an electric motor (20, 34) and at least three converters (52) coupled to the electric motor (20, 34), wherein the electric motor (20, 34) has at least two mutually independent winding sets (22), a first converter (52A) is coupled to a first winding set (22A) of the electric motor (20, 34), a second converter (52B) is coupled to a second winding set (22B) of the electric motor (20, 34), and a third converter (52B) can be selectively coupled to both the first winding set (22A) and / or the second winding set (22B) of the electric motor (20, 34) or at least one additional third winding set (22C), and wherein the converters (52) are configured such that the total maximum power output from all the converters (52) to the electric motor (20, 34) is equal to a maximum of 133% of the nominal actuator power demand.

2. The electronic steering system (12) of claim 1, characterized in that The converters (52) are configured and connectable to the winding sets (22) in such a way that in the event of a first fault in a converter (52), the electric motor (20, 34) can still be operated at least in a first fault mode in which the total power output from the fault-free converters (52) to the electric motor (20, 34) is still equal to at least 66% of the nominal actuator power demand.

3. The electronic steering system (12) of claim 2, characterized in that, The converters (52) are configured and connectable to the winding sets (22) in such a way that in the event of a second fault in a further converter (52), or, if, according to claim 1, there is initially only a first fault in a converter (52) in the event of a subsequent power supply failure, the electric motor (20, 34) can still be operated at least in a second fault mode in which the power output from the fault-free converters (52) to the electric motor (20, 34) is still equal to at least 33% of the nominal actuator power demand.

4. The electronic steering system (12) according to any one of the preceding claims, characterized in that The third converter (52) is configured such that a maximum of 33% of the nominal actuator power demand of each winding set (22) of the electric motor (20, 34) can be output by the third converter (52C) to the respective winding set (22).

5. The electronic steering system (12) according to any one of the preceding claims, characterized in that The converters (52) are configured and connectable to the winding sets (22) in such a way that each winding set (22) of the electric motor (20, 34) can be supplied with a power output of a maximum of 50% of the nominal actuator power demand.

6. The electronic steering system (12) according to any one of the preceding claims, characterized in that The third converter (52C) can be selectively additionally coupled to a fourth winding set (22D) of the electric motor (20, 34).

7. The electronic steering system (12) according to any one of the preceding claims, characterized in that A separate control logic unit (42) is assigned to each converter (52), wherein the plurality of control logic units (42) are connected to one another, or characterized in that a single shared control logic unit (42) is assigned to all the converters (52). A separate control logic unit (42) is assigned to each converter (52), wherein the plurality of control logic units (42) are connected to one another, or characterized in that a single shared control logic unit (42) is assigned to all the converters (52).

8. The electronic steering system (12) according to any of the preceding claims 2 to 7, characterized in that In the event of a failure of at least one converter (52) or a power failure, a fault notification can be output to the driver of the vehicle (10) and / or the maximum speed of the vehicle (10) can be reduced.

9. The electronic steering system (12) according to any one of the preceding claims, characterized in that The motor (20, 34) is 3n-phase, where n is greater than or equal to 1.

10. The electronic steering system (12) according to any one of the preceding claims, characterized in that At least the third converter (52C) ​​can be coupled to two different power supply circuits (56A, 56B) of the vehicle (10).

11. A method (50) for operating an electronic steering system (12) of a vehicle (10), wherein the electronic steering system (12) includes at least one actuator (18, 32) having an electric motor (20, 34) and at least three converters (52), the at least three converters (52) being coupled to the electric motor (20, 34), wherein the electric motor (20, 34) has at least two mutually independent winding sets (22), a first converter (52A) being coupled to a first winding set (22A) of the electric motor (20, 34), a second converter (52B) being coupled to a second winding set (22B) of the electric motor (20, 34), and the electronic steering system (12) further including a third converter (52C), wherein the converters (52) are configured such that a total maximum power output from all of the converters (52) to the electric motor (20, 34) is equal to a maximum of 133% of a nominal actuator power demand, and wherein the method (50) includes at least the following steps: - a fault in the electronic steering system (12) is detected, rendering the converter (52) no longer usable; and - selectively coupling the third converter (52C) ​​to the first winding set (22A) and / or the second winding set (22B) or at least one additional third winding set (22C) of the electric motor (20, 34).

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