Method and system for operating and / or testing a synchronous motor

Abstract

Method for operating a synchronous motor, in particular a robot drive (1), wherein a current supply to stator windings (20) of the synchronous motor in a compensation mode (S20) is controlled on the basis of a pilot control component (I komp ) for at least partial compensation of a cogging torque, the course of which, before the compensation operation, is predetermined during rotation of a rotor (21) of the synchronous motor in such a way that the pilot control component (I komp ) over a full revolution of the rotor (21) with a current required to successively hold a series of angular positions of the rotor (21) statically, wherein the pilot control component (I komp ) by means of a numerical evaluation of a mapping stored as a function between a value of an angular position of the rotor (21) or an electrical angle of a field-oriented current control and an associated value of the pilot control component (I komp) is determined, and wherein in a calibration operation (S10), in which the synchronous motor is operated in a position-controlled manner, a series of angular positions of the rotor (21) of the synchronous motor are successively approached and each held, in each of the held angular positions a current is detected with which stator windings of this synchronous motor are energized to hold the respective angular position.

Description

[0001] The present invention relates to a method and a system for operating and / or testing a synchronous motor and to a computer program or computer program product for carrying out the method.

[0002] For example, it is known from DE 10 2011 119 120 A1 that synchronous motors exhibit so-called cogging torque. The cogging torque of such a synchronous motor varies between maximum and minimum values ​​over a full rotation of a rotor. It is assumed that this is caused in particular by the varying reluctance depending on the angular position of the rotor.

[0003] To reduce such cogging torques, DE 10 2011 119 120 A1 proposes design features.

[0004] The article Y. Seki et al., “Quick Torque Ripple Suppression Control Fast Position Servo Based on Hybrid System of Disturbance Observer and Torque Ripple Table”, IECON 2015, ISBN 978-1-4799-1761-7 proposes a disturbance observer based on a zero-order disturbance observer and a torque fluctuation table.

[0005] DE 39 41 553 A1 relates to a control of an electric motor with a voltage or a current, the optimal curve of which is previously determined from the data of a pattern converter and stored in a function memory.

[0006] DE 10 2014 105 730 A1 relates to a method and an arrangement for reducing the torque ripple of a brushless DC motor having a stator, a rotor and a motor control unit via which the motor is controlled in multiple phases, with a data memory for storing angle-dependent correction data of the control current of the motor, which are impressed on the instantaneous values ​​for controlling the motor, wherein in a first step, for each position of the rotor, phase currents holding the rotor in this position are determined, from which reference current data are derived, which are stored in a table of the data memory together with the respective position data of the rotor determined by a position sensor, and in a second step, during ongoing operation of the motor, the position-dependent reference current data stored in the data memory are linked to the control current of the motor.

[0007] The object of the present invention is to improve the operation and / or testing of synchronous motors.

[0008] This object is achieved by a method having the features of claims 1 and 3, respectively. Claims 4 and 5 protect a system, computer program, or computer program product for implementing a method described herein. The subclaims relate to advantageous developments.

[0009] According to one embodiment of the present invention, a synchronous motor has a rotatable (mounted) rotor and a stator with electrical coil windings (“stator windings”) which are arranged distributed along a circumference of the rotor and are energized or supplied with current differently during operation in order to gradually change an angular position of the rotor.

[0010] In one embodiment, the rotor of the synchronous motor has at least one permanent magnet, in a further development at least one permanent magnet with at least two toothed rings with soft magnetic material.

[0011] Additionally or alternatively, the synchronous motor in one version is a stepper motor.

[0012] In one embodiment, the synchronous motor is a permanent magnet stepper motor or a hybrid stepper motor.

[0013] Additionally or alternatively, the synchronous motor in one embodiment is a synchronous motor of a robot drive.

[0014] The present invention is particularly advantageous for such synchronous motors, in particular due to the design, operating conditions and / or requirements.

[0015] According to one embodiment of the present invention, for or during operation of a synchronous motor, the current supply to stator windings of the synchronous motor is regulated in a compensation mode on the basis of or as a function of or taking into account a pilot control component for at least partially compensating a cogging torque, wherein a profile of this pilot control component, which is predetermined (already) before the compensation mode, is predetermined during or with respect to a rotation of a rotor of the synchronous motor in such a way that, in one embodiment, the pilot control component varies over a full revolution of the rotor with or in parallel, in particular synchronously and / or in phase, to a current, in particular periodically changes between maxima and minima, which is necessary for the successive, in one embodiment each static, holding of a series of angular positions of the, in one embodiment, load-free rotor.the pilot control component is specified in such a way (before the compensation operation) that the pilot control component has maxima in angular positions of the rotor, which in one version is load-free, in which a current also has maxima which is required to hold the respective angular position, which in one version is static, and has minima in angular positions in which the current required to hold the respective angular position also has minima.

[0016] One embodiment of the present invention is based on the idea of ​​at least partially compensating a cogging torque, in particular model-supported, by a correspondingly (optimized) current supply or application or supply with current or electrical supply, instead of or in addition to at least partial compensation of a cogging torque by design features: by taking into account or using a corresponding pilot control component when regulating the current supply, the cogging torque can be compensated - at least partially - more simply, more precisely and / or more reliably.

[0017] As a result, the synchronous motor can be operated or controlled in a particularly advantageous manner, in particular more simply, more precisely, more smoothly and / or more reliably.

[0018] In one embodiment, the current supply is controlled by means of a field-oriented current control, wherein in a further development the pilot control component is added to a current setpoint which, in one embodiment, is supplied to the field-oriented current control by a position or speed controller.

[0019] By means of a field-oriented current control, the synchronous motor in a design in conjunction with the pilot control component can be operated or controlled particularly advantageously, in particular more simply, more precisely and / or more reliably.

[0020] In one embodiment, the pilot control component is determined using a table with stored angular positions of the rotor or electrical angles of a field-oriented current control and associated stored values ​​of the pilot control component.

[0021] This can simplify and / or accelerate a determination in one embodiment and thus improve control or operation.

[0022] In one embodiment, the pilot control component is determined by means of a numerical evaluation of a mapping stored as a function between a value of an angular position of the rotor or an electrical angle of a field-oriented current control and an associated value of the pilot control component.

[0023] This can reduce memory requirements and / or increase accuracy in one embodiment, thereby improving control or operation.

[0024] In one embodiment, the pilot control component varies periodically with an angular position of the rotor; in a further development, it is determined on the basis of a detected angular position of the rotor.

[0025] Additionally or alternatively, in one embodiment, the pilot control component varies periodically with an electrical angle of a field-oriented current control, in particular a torque-generating or cross-current; in a further development, it is determined on the basis of the electrical angle, which in turn is determined in one embodiment on the basis of a detected angular position of the rotor.

[0026] In one embodiment, the pilot control component varies sinusoidally with the angular position of the rotor or the electrical angle of the field-oriented current control.

[0027] Additionally or alternatively, the pilot control component in one embodiment has a constant component, which can be used in particular to compensate for external conservative or non-conservative forces.

[0028] Preferably, the constant portion of the pilot control component compensates for a frictional force and / or is always added to the torque-generating current - counter to the frictional effect.

[0029] Thus, the input tax component I komp in one embodiment, a predetermined course during rotation of the rotor according to lcomp=lconst+A⋅sin(B⋅φel) with the constant proportion I konst , the amplitude A, the spatial frequency B and the electrical angle φ el , in [rad], which in one version is translated i=nel / nmech=φel / φmech with the speed n mech of the rotor and the corresponding speed n el of the stator field from the detected angular position φ mechof the rotor. The (local) frequency B is equal to 4 (B = 4) in one embodiment. An electrical angle of a field-oriented current control is, in one embodiment, a commutation angle and / or an angle of the torque-generating or cross-current.

[0030] Additionally or alternatively, the feedforward control component is determined in one embodiment by a finite Fourier series that maps this angle-dependent periodicity, so that the function is represented by the corresponding Fourier coefficients (A i , B i , C i , D i , with i = 0,..N) can be described as: lkomp=lkonst+∑i=0NAisin(Biϕel)+Cicos(Diϕel)

[0031] By means of one or more of these features, the synchronous motor in one embodiment can be operated or controlled particularly advantageously, in particular more simply, more precisely, more smoothly and / or more reliably.

[0032] According to one embodiment of the present invention, in order to operate a synchronous motor or the synchronous motor (initially) in a calibration mode, a series of angular positions of a rotor of a (first) synchronous motor, which in one embodiment is load-free, are successively approached and held in each case and in the held angular positions in each case, in one embodiment after expiry of a predetermined settling time, which is preferably at least 100 ms, a current is detected with which stator windings of this (first) synchronous motor are energized in order to hold the respective angular position.

[0033] According to one embodiment of the present invention, on the basis of these angular positions and detected currents, in a further development on the basis of electrical angles determined on the basis of the angular positions and / or on the basis of the currents averaged and / or low-pass filtered for the respective angular position or the respective electrical angle, a pilot control component is parameterized for at least partial compensation of a cogging torque and then this (first) synchronous motor and / or another synchronous motor, preferably of the same type (to the first synchronous motor), is operated on the basis of or taking into account or using this parameterized pilot control component, in one embodiment controlled, in a further development according to a method described here or in the compensation mode described here. In one embodiment, the constant component I konstand / or the amplitude A and / or the spatial frequency B of equation (1) and / or the Fourier coefficients of equation (3) are parameterized.

[0034] In addition or as an alternative to operating or controlling in a compensation mode described here based on the pilot control component parameterized in calibration mode, according to one embodiment of the present invention, the synchronous motor is tested based on the angular positions and detected currents, in a further development based on electrical angles determined based on the angular positions and / or based on the currents averaged and / or low-pass filtered for the respective angular position or the respective electrical angle, and in one embodiment, errors, inaccuracies or the like are identified and / or quantified. In one embodiment, an error in the synchronous motor is determined based on a deviation of the detected currents from a target distribution specified for the angular positions or electrical angles.

[0035] In one embodiment, the synchronous motor is operated in a position-controlled manner in the compensation mode and / or the calibration mode, wherein in one embodiment the position control is arranged in an outer cascade or an outer control loop and the field-oriented current control is arranged in an inner cascade or an inner control loop of a cascade control, in a further development with an intermediate speed control in an intermediate cascade or an intermediate control loop.

[0036] According to one embodiment of the present invention, a system for operating a synchronous motor or the synchronous motor is configured, in particular in terms of hardware and / or software, in particular programming, to carry out a method described here and / or has a controller, in one embodiment a (drive) circuit board, which energizes the stator windings of the synchronous motor in a compensation mode on the basis of a pilot control component for at least partially compensating a cogging torque, the course of which, predetermined before the compensation mode, is predetermined during a rotation of a rotor of the synchronous motor in such a way that the pilot control component varies over a full revolution of the rotor with a current which is necessary for successively holding a series of angular positions of the rotor, or the controller or the circuit board is configured or used for this purpose.

[0037] In one embodiment, the system (additionally) comprises the synchronous motor, in particular the robot drive, in one embodiment a robot with this robot drive.

[0038] A system, a controller, a control system, and / or a module within the meaning of the present invention can be designed in hardware and / or software, in particular at least one, in particular digital, processing unit, in particular a programmable integrated circuit (IC), microcontroller unit (MCU), microprocessor unit (CPU), graphics card (GPU), or the like, preferably data- or signal-connected to a memory and / or bus system, and / or one or more programs or program modules. The processing unit can be designed to execute commands implemented as a program stored in a memory system, to acquire input signals from a data bus, and / or to output output signals to a data bus. A memory system can have one or more, in particular different, storage media, in particular optical, magnetic, solid-state, and / or other non-volatile media.The program can be designed in such a way that it embodies or is capable of carrying out the methods described here, so that the processing unit can carry out the steps of such methods and thus in particular can operate the synchronous motor. In one embodiment, a computer program product can have, in particular be, a storage medium, in particular a computer-readable and / or non-volatile one, for storing a program or instructions or with a program or instructions stored thereon. In one embodiment, execution of this program or these instructions by a system or a controller, in particular a computer or an arrangement of several computers, causes the system or the controller, in particular the computer(s), to carry out a method described here or one or more of its steps, or the program or the instructions are configured to do so.

[0039] In one embodiment, one or more, in particular all, steps of the method are carried out completely or partially automatically, in particular by the system or its controller(s).

[0040] Further advantages and features emerge from the subclaims and the exemplary embodiments. The following shows, partially schematically: Fig. 1: a system for operating a synchronous motor according to an embodiment of the present invention; Fig. 2: a method for operating the synchronous motor according to an embodiment of the present invention; Fig. 3: a controller of the system; Fig. 4: a curve of a pilot control component during rotation of a rotor of the synchronous motor; Fig. 5: the rotor; and Fig. 6: Currents recorded in a defective synchronous motor.

[0041] Fig. Figure 1 shows a system for operating a synchronous motor of a robot drive 1 of a robot 100 according to an embodiment of the present invention. Application to robots (drives) can be particularly advantageous, particularly due to the precision and / or smooth running required, without the invention being limited thereto. Reference numeral 2 indicates a control device for operating or controlling the (synchronous motors) of the robot drives of the robot 100.

[0042] Fig. 2 shows a method for operating the synchronous motor according to an embodiment of the present invention.

[0043] In a calibration operation S10, a series of angular positions φ mecha load-free rotor of a synchronous motor is approached and held in a position-controlled manner, which is preferably of the same type as the synchronous motor of the robot drive 1. In one embodiment, the successive angular positions are offset from one another by at least 0.01° and / or at most 0.1° and / or are each held until a steady state is reached.

[0044] In the angular positions held in position control, a current is recorded with which the stator windings of this synchronous motor are energized to hold the respective angular position.

[0045] Fig. 4 shows corresponding values ​​of the cross current of a field-oriented current control via its electrical angle φ el , which is based on a known translation from the respective angular position φ mech The electrical angle φ elon the abscissa, and the recorded currents or measured values ​​are displayed as individual points. Due to the position control, these currents or measured values ​​fluctuate, so averaging and / or low-pass filtering are performed.

[0046] With I komp a pre-control component is indicated, which is specified as a sine function with a constant component and which is parameterized or whose parameters are determined in such a way that it optimally approximates the recorded and averaged or low-pass filtered currents or measured values, in the example example lcomp=90 mA+80 mA⋅sin(4⋅φel)

[0047] In a compensation operation S20, the synchronous motor of the robot drive 1, preferably of the same type, is then controlled on the basis of this parameterized pilot control component I komp operated, in particular regulated.

[0048] Fig. 3 shows a corresponding (cascade) controller with a position control 10, a speed control 11 and a field-oriented current control 12.

[0049] The current control 12 energizes the stator windings 20 of the synchronous motor. It receives actual values ​​from a current measurement 30 and setpoint values ​​from the speed control 11.

[0050] The position control 10 receives a target angular position or target angular position change or target steps as well as angular positions φ detected by an angular position measurement 31 mech of a rotor 21 of the synchronous motor, determines therefrom in a manner known per se a target speed and outputs this to the speed control 11, which by means of differentiation 40 from detected angular positions φ mech receives an actual speed of the rotor 21, determines a target current from this in a manner known per se and outputs this to the current control 12.

[0051] The difference between the target and actual current is assigned the pilot control component I before entering the current control 12. komp added, which is calculated in a module 50 based on the detected angular position φ mech which is converted into the corresponding electrical angle φ el With this electrical angle φ el The pilot control component I can then be calculated from a stored table or alternatively by numerical evaluation of a mapping stored as a function between a value of the electrical angle and the corresponding value of the pilot control component according to the parameterized equation (1) or (1a). komp determined and added to the control difference between the target and actual current, as in Fig. 3 indicated.

[0052] Fig. Figure 5 shows a perspective view of the rotor 21 and part of a stator with stator windings 20 and stator poles 20A, with parts of the rotor and stator hidden for clarity. 21A indicates a permanent magnet, and 21B indicates two toothed rings made of soft magnetic material.

[0053] In addition to or instead of parameterization I komp The pilot control component allows the synchronous motor to be tested in calibration mode based on the angular positions and recorded currents.

[0054] Fig. 6 shows, as an example, the recorded currents over the electrical angle determined from the recorded angular positions in Fig. 4 correspondingly for a synchronous motor with a defective stator winding. One can clearly see the deviation of the mean value of the measured currents (points in Fig. 6) from a sinusoidal target distribution specified for the angular positions or electrical angles, such as that parameterized for a synchronous motor of the same type as described above. Based on this deviation, a corresponding error of the synchronous motor can be determined.

[0055] In a method for testing a synchronous motor according to an embodiment of the present invention, Fig. 2 the compensation operation S20 is omitted.

[0056] Although exemplary embodiments have been explained in the foregoing description, it should be noted that numerous modifications are possible. Furthermore, it should be noted that the exemplary embodiments are merely examples and are not intended to limit the scope of protection, applications, or structure in any way. Rather, the foregoing description provides the skilled person with a guide for implementing at least one exemplary embodiment, whereby various changes, particularly with regard to the function and arrangement of the described components, can be made without departing from the scope of protection as it results from the claims and equivalent combinations of features. List of reference symbols 1 robot drive 2 control device 10 Position control 11 Speed ​​control 12 field-oriented current control 20 stator winding(s) 20A stator pole 21 Rotor 21A permanent magnet 21B toothed rings 30 Current measurement 31 Angular position measurement 40 Differentiation 50 modules 100 robots I komp Input tax component S10 Calibration operation S20 compensation operation

Claims

[1] Method for operating a synchronous motor, in particular a robot drive (1), wherein a current supply to stator windings (20) of the synchronous motor in a compensation mode (S20) is controlled on the basis of a pilot control component (I komp ) for at least partial compensation of a cogging torque, the course of which, prior to the compensation operation, is predetermined during rotation of a rotor (21) of the synchronous motor in such a way that the pilot control component (I komp ) over a full revolution of the rotor (21) with a current required to successively hold a series of angular positions of the rotor (21) statically, wherein the pilot control component (I komp ) by means of a numerical evaluation of a mapping stored as a function between a value of an angular position of the rotor (21) or an electrical angle of a field-oriented current control and an associated value of the pilot control component (I komp) is determined, and wherein in a calibration operation (S10), in which the synchronous motor is operated in a position-controlled manner, a series of angular positions of the rotor (21) of the synchronous motor are successively approached and each held, in each of the held angular positions a current is detected with which stator windings of this synchronous motor are energized to hold the respective angular position. [2] Method according to claim 1, characterized by that the input tax component (I komp ) with an angular position of the rotor (21) and / or an electrical angle of a field-oriented current control periodically, in particular sinusoidally, varies and / or has a constant component. [3] Method for operating and / or testing a synchronous motor, in particular a robot drive (1), wherein in a calibration operation (S10), in which the synchronous motor is operated in a position-controlled manner, a series of angular positions of a rotor (21) of a synchronous motor are successively approached and each held, in the held angular positions a current is detected in each case, with which stator windings of this synchronous motor are energized to hold the respective angular position, wherein on the basis of these angular positions and detected currents a) this synchronous motor is tested, whereby a fault of the synchronous motor is determined on the basis of a deviation of the measured currents from a target distribution specified for the angular positions or electrical angles determined on the basis of the angular positions; and / or b) an input tax component (I komp) is parameterized for at least partial compensation of a cogging torque and another, in particular of the same type, synchronous motor is then controlled on the basis of this parameterized pilot control component (I komp ) is operated, in particular regulated. [4] System for operating a synchronous motor, in particular a robot drive (1), which is designed to carry out a method according to one of the preceding claims. [5] Computer program or computer program product, wherein the computer program or computer program product contains instructions, in particular stored on a computer-readable and / or non-volatile storage medium, which, when executed by one or more computers or a system according to claim 4, cause the computer(s) or the system to carry out a method according to one of claims 1 to 3.

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