Actuator and method for controlling at least one actuator

Abstract

The invention relates to an actuating device with at least one actuator for actuating an actuator output to which an end effector can be arranged, wherein the actuator comprises: - a synchronous motor with a rotor and a stator, - a motor control configured for controlling the synchronous motor by generating and applying a set electrical voltage to the synchronous motor in order to rotate the rotor relative to the stator and actuate the actuator output, - at least one actuator position sensor configured for detecting actuator position information at the actuator output, and - at least one rotor position sensor configured for detecting measured rotor position information of the rotor, characterized in that - the actuator has at least one current sensor for detecting a current flow when the generated set electrical voltage is applied to the synchronous motor, and - the actuator includes a encoderless rotor position estimation.which estimates the rotor position information based on the generated target voltage and / or a measured actual voltage and the detected current flow, - wherein the motor control is configured to generate the target voltage for controlling the synchronous motor based on the detected actuator position information, the measured rotor position information and the estimated rotor position information.

Description

The invention relates to an adjusting device having at least one actuator for actuating an actuator output, on which an end effector can be arranged. The invention also relates to a flying object with such an adjusting device for this purpose.The invention also relates to a method for controlling an actuator, which has a synchronous motor with a rotor and a stator, in order to actuate an actuator output, at which an end effector can be arranged.Not only in aerospace applications are actuators used which serve as actuators in a control loop. In this case, electrical energy is converted by the actuators into mechanical movement in order to actuate the end effectors arranged at the actuator output.In the case of flying objects, such as aircraft or helicopters, such actuators are used in flyby-wire system architectures in order to use the control commands input by the pilot for the actuation of the control surfaces of the primary and secondary flight control. In this case, the control commands are converted into electronic control signals and subsequently, based thereon, corresponding electrical signals are generated, which serve for controlling the actuator, more precisely the electric motor on which the actuator is based.The electric motor generates a rotational movement which is then present in the desired mechanical movement at the actuator output depending on the application. The mechanical drive train frequently comprises conversion gears for reducing the output rotational speed and / or ball screws for converting the rotational movement of the electric motor into a linear movement. This linear movement can then be used, for example, to actuate the control surfaces of the flying object. Such an electric motor can be a permanent magnet synchronous motor, for example.Such electromechanical actuators with an electric motor are often operated in a field-oriented cascade control in the flight control area. The position control loop is the outer cascade and adjusts the actuator position information with respect to a position sensor at the actuator output, e.g. an LVDT or an RVDT. The middle cascade is the speed control loop which regulates the engine speed. As a rule, an input sensor is used here as an encoder on the motor shaft, for example a resolver which detects the rotor position and thus also indirectly the motor speed. The inner loop regulates current flow based on current sensors on the motor phases. The current vector must be fed in with respect to the rotor-fixed, electrical coordinate system, i.e. field-oriented.Feeding as accurately as possible in the transverse direction of the permanent magnets, i.e. in the 90° axis in the rotor-fixed electrical coordinate system, permits particularly efficient motor operation. This again requires accurate detection of the rotor position. Due to the high criticality of the rotary encoder, the rotor position is frequently detected in double or multiply redundant fashion in safety-critical applications such as flight control.The redundant detection of the rotor position generally requires the multiple redundant application of rotary encoders on the rotor shaft, as a result of which the hardware complexity of electromechanical actuators is increased. This has negative effects on the costs, the weight and the installation outlay for the sensors and also its supply line and the evaluation electronics. Moreover, the integration of electromechanical actuators in restricted installation situations is made more difficult and the mass inertia of the rotor shaft is increased.Methods of rotary encoder-free control are known which allow motor control without the measurement of the rotor position using a physical sensor and in the process use sufficiently accurate rotor position estimation instead. At a sufficiently high engine speed, the fundamental wave of the electric motor is frequently evaluated for estimating the rotor position. A rotating rotor induces a directed voltage vector into the motor phases, the so-called back electromotive force (back EMF). By systematically evaluating setpoint voltages and measured phase currents, conclusions can be drawn about the rotor position.In the simplest case, the motor voltage equation is solved directly by integration or differentiation of the phase currents. Other estimation methods also make use of observers, e.g. Luenberger or Kalman filters, model reference adaptive systems (MRAS), or artificial intelligence.At low engine speed and at standstill, anisotropy-based methods are frequently used. Anisotropy in this context denotes a magnetic asymmetry of the rotor, which is manifested by inductances of different sizes in the longitudinal and transverse directions of the permanent magnets. Anisotropy-based rotor position estimators are distinguished by the systematic injection of specific voltage patterns and the methodological demodulation of the current response caused thereby. They can be categorized basically by the type of voltage patterns. For example, present day methods use pulse, sine and square injection patterns or else the so-called arbitrary injection. A great degree of familiarity is experienced by the INFORM method based on pulse injection, as well as by the rotating and alternating injection methods based on sinusoidal injection.It is disadvantageous that estimation methods in safety-critical (aviation) applications are not regarded as reliable enough as the sole means for detecting the rotor position.It is therefore the object of the present invention to specify an improved actuating device and an improved method for actuating an actuator of such an actuating device.The object is achieved according to the invention with the adjusting device according to claim 1. Advantageous embodiments of the adjusting device are then found in the corresponding dependent claims.According to claim 1, an adjusting device with at least one actuator for actuating an actuator output is proposed, wherein an end effector can be arranged at the actuator output. Such an end effector can be, for example, a valve or a control surface of an aerial object. The actuator output supplies the intended mechanical movement that the actuator is intended to perform as intended.The actuator includes a synchronous motor having a rotor and a stator. In addition, the actuator has at least one actuator position sensor which is designed to record actuator position information at the actuator output, and at least one rotor position sensor which is designed to record measured rotor position information of the rotor. If the actuator is operated in a (field-oriented) cascade control, the actuator position sensor provides the actuator position information for the position control loop of the outer cascade and the rotor position sensor provides the rotor position information of the rotor for the speed control loop of the middle cascade and for the (field-oriented) current control of the lower cascade.The synchronous motor is now controlled by means of motor control. The synchronous motor is actuated in such a way that an electrical setpoint voltage is generated and applied to the synchronous motor in order to rotate the rotor with respect to the stator and to actuate the actuator output. The generation of the setpoint voltages is effected, inter alia, on the basis of the actuator position information of the actuator position sensor and the rotor position information of the rotor position sensor.According to the invention, it is now provided that the actuator has at least one current sensor for detecting a current flow when the generated setpoint voltage is applied to the synchronous motor, and the actuator comprises a rotary encoder-free rotor position estimate which estimates estimated rotor position information of the rotor as a function of the generated setpoint voltage and / or a measured actual voltage and the detected current flow, wherein the motor controller is configured to generate the setpoint voltage for actuating the synchronous motor as a function of the detected actuator position information, the measured rotor position information and the estimated rotor position information. As a rule, at least two current sensors are provided in a three-phase synchronous motor.According to the invention, it is accordingly provided to use a method of rotary encoder-free rotor position estimation for monitoring sensors in electromechanical actuators. The additional analytical redundancy allows the detection and clear isolation of an erroneous but valid sensor signal of a physical rotor position sensor (e.g. a resolver) or of the position sensor at the actuator output (e.g. an RVDT or LVDT). A significant deviation between the position detections of the rotor position sensor, the rotor position estimator and the position sensor at the actuator output indicates a faulty signal. A comparison between the three signal values can be achieved with knowledge of the transmission ratio and, if appropriate, the compensation of mechanical effects of the drive train (e.g. rigidity and play). The isolation of the erroneous signal is performed by majority decision. The incorporation of methods of rotary encoder-free rotor position estimation thus allows the omission of a redundant, physical rotor position sensor for fault diagnosis.It is therefore provided in a particularly advantageous embodiment that only a single actuator position sensor and only a single rotor position sensor are provided in the actuator, so that the necessary redundancy takes place via the rotary encoder-free rotor position estimation. In an advantageous embodiment, exactly two actuator position sensors and / or two rotor position sensors can be provided.The rotor position sensor acquires rotor position information which can be, for example, the absolute position of the rotor with respect to a reference point and / or the rotational speed of the rotor.The actuator position sensor can, for example, detect the movement of the actuator output, for example the linear movement, and provide it as actuator position information. It can be, for example, the speed of movement (for example. Linear motion speed or rotational speed). From this actuator position information, it is now possible to infer an actuator-related rotor position information by inversely knowing the conversion gearing between the rotor and the actuator output. The actuator position sensor can, however, also represent an absolute position indication, wherein the actuator-related rotor position information can then be deduced via the relative change of this actuator position.The rotor position sensor and the actuator position sensor are provided here at different locations of the actuator. The actuator position sensor is basically not a rotor position sensor and also does not directly record rotor information as actuator position information.According to one specific embodiment, it is provided that the motor controller is set up to ascertain a correct sensor state of all sensors and / or an erroneous sensor state of at least one sensor as a function of the estimated rotor position information, the measured rotor position information and the detected actuator position information.In this case, it can be provided that the motor controller is configured to compare the estimated rotor position information, the measured rotor position information and an actuator-related rotor position information derived from the detected actuator position information with one another and then to infer a correct sensor state of all sensors and / or a faulty sensor state of at least one sensor as a function of the comparison.However, it is also conceivable for the measured rotor position information and the estimated rotor position information to be projected onto the actuator output and be compared there. The motor controller is then configured to compare an estimated actuator position information derived from the estimated rotor position information, a calculated actuator position information derived from the measured rotor position information and the detected actuator position information with one another and then to infer a correct sensor state of all sensors and / or an erroneous sensor state of at least one sensor as a function of the comparison.By comparing the at least three sensor information items, it is possible to infer an erroneous sensor state, for example, by majority decision. This is the case, for example, when two of the three items of sensor information are identical within a tolerance range and only the third item of sensor information deviates therefrom. However, the comparison presupposes that the sensor information is present in a format which permits a meaningful comparison. This would be, for example, the rotational speed of the rotor or the actuator output.According to one specific embodiment, it is provided that the motor controller is set up to ascertain the sensor state as a function of a gear ratio between synchronous motor and actuator output.In this case, it can be provided that the motor control is configured to calculate the actuator-related rotor position information as a function of a gear ratio between synchronous motor and actuator output.Knowing the movement or movement speed of the actuator at the actuator output, it is possible to infer the rotational speed of the rotor with knowledge of a transmission ratio. Actuator-related rotor position information can thus be calculated from the movement of the actuator output.However, it is also conceivable that the motor control is configured to calculate the derived estimated actuator position information and the derived calculated actuator position information as a function of a gear ratio between synchronous motor and actuator output. As a result, both the estimated and the measured rotor position information of the rotor can be projected onto the actuator output.According to one specific embodiment, it is provided that the motor controller is set up to perform reconfiguration based on the estimated rotor position information and the detected actuator position information (for example, the actuator-related rotor position information) after the detection of a faulty rotor position sensor.Such reconfiguration may mean, for example, that the faulty rotor position sensor is disregarded in calculating the target voltage for driving the synchronous motor and is instead replaced by another piece of sensor information.It is also conceivable, however, that reconfiguration is understood to mean that the offset of the error, provided it is sufficiently constant and recognizable, is compensated by an offset, whereby the sensor can also continue to find input into the regulation.According to one specific embodiment, it is provided that the motor controller is set up to perform reconfiguration based on the estimated rotor position information and the measured rotor position information after the detection of a faulty actuator position sensor.As in the previous exemplary embodiment, reconfiguration can also be understood here to mean that the faulty actuator position sensor is disregarded or that, given a sufficiently constant and recognizable deviation of the fault, the fault is compensated according to its offset.According to one embodiment, it is provided that the rotor position sensor comprises at least one rotary encoder on the rotor shaft of the rotor.According to one embodiment, it is provided that the synchronous motor is a permanent magnet synchronous motor.A further aspect of the present invention is a flying object having control surfaces for flight control, wherein the control surfaces are actuated by an actuating device as described above.A further aspect of the present invention is a method for driving an actuator having a synchronous motor with a rotor and a stator in order to actuate an actuator output at which an end effector can be arranged, wherein the method comprises the following steps:generating a setpoint electrical voltage and applying the setpoint voltage to the synchronous motor by means of a motor controller in order to rotate the rotor with respect to the stator and to actuate the actuator output,detecting an actuator position information at the actuator output by means of at least one actuator position sensor,detecting measured rotor position information of the rotor by means of at least one rotor position sensor, characterized bydetecting a current flow when applying the generated setpoint voltage to the synchronous motor by means of at least one current sensor,estimating an estimated rotor position information item of the rotor by means of a rotary encoder-free rotor position estimate as a function of the generated setpoint voltage and / or a measured actual voltage and the detected current flow, andgenerating the setpoint voltage for driving the synchronous motor as a function of the detected actuator position information, the measured rotor position information and the estimated rotor position information by means of the motor controller.Advantageous embodiments of the method are then found in the corresponding dependent claims.The invention is explained in more detail by way of example with reference to the attached figure. It shows: FIG. 1 shows a block diagram of an electromechanical actuator with fault-tolerant regulation.FIG. 1 shows a block diagram of an electromechanical actuator 15 with a fault-tolerant control system, in which a rotary encoder-free rotor position estimate 13 is used. The example of application described in FIG. 1 aims at using the actuator 15 for the actuation of control surfaces of the primary and secondary flight control.The actuator 15 follows a control command which is typically received from a flight control computer (not shown). The actuator control system comprises three cascaded control circuits for the operation of the integrated permanent magnet synchronous motor 8. From this, a setpoint current is generated in the rotor-fixed coordinate system and transferred to the current regulator 3.Frequently, only a torque-forming setpoint current component is commanded in the transverse direction of the permanent magnets of the synchronous motor and a setpoint current of zero is set in the longitudinal direction. The current regulator outputs a setpoint voltage in the rotor-fixed coordinate system, which is transferred into the stator-fixed coordinate system with knowledge of the electric rotor angle. The inverse Park transformation 4 is usually used for this purpose.Pulse width-controlled switching intervals are modulated from the setpoint voltages in 5 and these switch intervals operate the switching elements of the inverter 6 in such a way that the desired phase voltages are established on the permanent magnet synchronous motor 8 on average over time. The motor is often followed by a gear 10, by means of which the rotational speed at the output is reduced and subsequently optionally transformed into a linear movement (e.g. by a ball screw).The actuator comprises a plurality of sensors which feed back the control variables to the corresponding controllers 1, 2, 3 and to the transformation matrices 4, 14. The current flows induced by the setpoint voltage are measured by current sensors 7 and transferred into the rotor-fixed coordinate system with knowledge of the rotor angle. The dq transformation 14 is usually used for this purpose.On the motor shaft, the rotor position angle and the rotor rotational speed are detected by a rotary encoder 9, e.g. a resolver, and provided as measured rotor position information. At the actuator output, the actuator position is measured by the position sensor 11, e.g. an LVDT or RVDT. The actuator position can be detected over time and provided as actuator position information.The signals of the rotor position sensor 9 and of the actuator position sensor 11 are now not fed back directly to the corresponding controllers 1, 2 and transformation matrices 4, 14, as is known in the prior art. Instead, a rotary encoder-free rotor position estimation 13 is carried out at the same time, which generates a redundant estimated value of the rotor position angle and of the motor speed as estimated rotor position information.Conventional methods use the measured current flows for the estimation on the one hand and the commanded setpoint voltages, for example the individual phase voltages, on the other hand. Injection-based methods also superimpose a dedicated voltage pattern on the target voltages.The estimated rotor position information is compared in module 12 with the measured values of rotor position sensor 9 and actuator position sensor 11. Based on this, error detection and isolation by majority decision takes place.In the error-free nominal case, the signal values of the physical sensors 9, 11 are fed back to the controllers 1, 2 and the transformation matrices 4, 14. In the case of successful diagnosis of a sensor fault of the rotor position sensor 9 or of the actuator position sensor 11, a rapid reconfiguration takes place, which ensures reliable continued operation and thus gives the actuator a fault tolerance.An erroneous measurement of rotor position angle and motor speed by the rotor position sensor 9 is compensated by the estimation of the rotor position estimator 13. An erroneous measurement of the actuator position 11 is compensated for by the measurement 9 or estimation 13. For this purpose, the rotor position angle is projected onto the actuator output with knowledge of the drive train of the actuator.List of reference characters1 Position controller 2 Speed controller 3 Current controller 4 Transformation matrix / inverse Park transformation 5 Pulse width modulation / pulse width controlled switching intervals 6 Inverter 7 Current sensors 8 Synchronous motor 9 Rotor position sensor / rotary encoder 10 Transmission 11 Actuator position sensor / position sensor 12 Comparison module 13 Rotor position estimate 14 Transformation matrix / dq transformation 15 Actuator 16 Motor controller

Claims

Actuating device having at least one actuator (15) for actuating an actuator output, at which an end effector can be arranged, wherein the actuator (15) has: - a synchronous motor (8) having a rotor and a stator, - a motor controller (16) which is designed to actuate the synchronous motor (8) by generating an electrical setpoint voltages and applying them to the synchronous motor (8) in order to rotate the rotor with respect to the stator and to actuate the actuator output, - at least one actuator position sensor (11) which is designed to record actuator position information at the actuator output, and - at least one rotor position sensor (9) which is designed to record measured rotor position information of the rotor, characterized in that - the actuator (15) has at least one current sensor (7) for recording a current flow when applying the generated setpoint voltage to the synchronous motor (8), and - the actuator (15) comprises a rotary encoder-free rotor position estimate (13) which estimates estimated rotor position information of the rotor as a function of the generated setpoint voltage and / or a measured actual voltage and the detected current flow, - wherein the motor controller (16) is configured to generate the setpoint voltage for driving the synchronous motor (8) as a function of the detected actuator position information, the measured rotor position information and the estimated rotor position information.Adjusting device according to Claim 1, characterized in that the motor controller (16) is set up to determine a correct sensor state of all sensors and / or an erroneous sensor state of at least one sensor as a function of the estimated rotor position information, the measured rotor position information and the detected actuator position information.Actuating device according to Claim 2, characterized in that the motor controller (16) is configured to determine the sensor state as a function of a transmission ratio between synchronous motor (8) and actuator output.Actuating device according to Claim 2 or 3, characterized in that the motor controller (16) is configured, after the detection of a faulty rotor position sensor (9), to carry out reconfiguration on the basis of the estimated rotor position information and the detected actuator position information.Actuating device according to one of Claims 2 to 4, characterized in that the motor controller (16) is configured, after the detection of a faulty actuator position sensor (11), to carry out reconfiguration on the basis of the estimated rotor position information and the measured rotor position information.Adjusting device according to one of the preceding claims, characterized in that the rotor position sensor (9) comprises at least one rotary encoder (9) on the rotor shaft of the rotor.Actuating device according to one of the preceding claims, characterized in that the synchronous motor (8) is a permanent magnet synchronous motor (8).A flying object having control surfaces for flight control, wherein the control surfaces are actuated by an actuating device according to one of the preceding claims.Method for controlling an actuator (15) which has a synchronous motor (8) with a rotor and a stator in order to actuate an actuator output at which an end effector can be arranged, wherein the method comprises the following steps: - generating an electrical setpoint voltage and applying the setpoint voltage to the synchronous motor (8) by means of a motor controller (16) in order to rotate the rotor with respect to the stator and to actuate the actuator output, - detecting actuator position information at the actuator output by means of at least one actuator position sensor (11), - detecting measured rotor position information of the rotor by means of at least one rotor position sensor, characterized by - detecting a current flow when applying the generated setpoint voltage to the synchronous motor (8) by means of at least one current sensor (7), estimating an estimated rotor position information item of the rotor by means of a rotary encoder-free rotor position estimate (13) as a function of the generated setpoint voltage and / or a measured actual voltage and the detected current flow, and generating the setpoint voltage for driving the synchronous motor (8) as a function of the detected actuator position information item, the measured rotor position information item and the estimated rotor position information item by means of the motor controller (16).Method according to Claim 9, characterized in that, as a function of the estimated rotor position information, the measured rotor position information and the detected actuator position information, a correct sensor state of all sensors or an erroneous sensor state of at least one sensor is established by means of the motor controller (16).Method according to Claim 10, characterized in that the sensor state is determined as a function of a transmission ratio between synchronous motor (8) and actuator output.Method according to Claim 10 or 11, characterized in that, after the detection of a faulty rotor position sensor (9), reconfiguration is carried out by the motor controller (16) on the basis of the estimated rotor position information and the recorded actuator position information.Method according to one of Claims 10 to 12, characterized in that, after the detection of a faulty actuator position sensor (11), reconfiguration is carried out on the basis of the estimated rotor position information and the measured rotor position information by the motor controller (16).

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