Method for detecting the rotational position of a rotor of a permanent magnet synchronous machine and arrangement for carrying out this method

Abstract

Method for detecting a rotational position of a rotor of a permanent magnet synchronous machine (101), wherein • a first measurement signal (uc) designed as an alternating signal in rotor coordinates (d, q) is provided, transformed by a transformer control signal to the transformer stage (112) in stator coordinates (a, b) and fed into the permanent magnet synchronous machine (101), • the first measurement signal (uc), transformed in stator coordinates (a, b) and formed by a carrier voltage (uc), generates a second measurement signal (ic, ic1, ic2) as a reaction in at least one stator winding of the permanent magnet synchronous machine (101), designed as an alternating signal and formed by a carrier current (ic, ic1, ic2). • the second measurement signal (ic, ic1, ic2) is measured and back-transformed into the rotor coordinates (d, q) by the transformer control signal to the transformer stage (113), • an angle difference to the first measurement signal (uc) is obtained from the second measurement signal (ic, ic1, ic2) which has been transformed back into the rotor coordinates (d, q), • the transform control signal is formed from the angle difference by PI control and subsequent integration, and the transform control signal forms a measure of the rotational position of the rotor, • through the PI control, the angle difference is further regulated at least almost to zero, thereby achieving an alignment of the orientation of a real axis (d) of the rotor coordinates (d, q) with a rotor axis (118) along which a resultant permanent magnet flux of the rotor caused by permanent magnets encompassed by the rotor is aligned, • to determine the polarity of the permanent magnet flux with respect to the real axis (d) of the rotor coordinates (d, q), at least one operating point setting signal (ia, ua) is additively superimposed on the first measurement signal (uc). • a change in the amplitude of the second measurement signal (ic, ic1, ic2) is caused by at least one operating point setting signal (ia, ua) superimposed on the first measurement signal (uc) and • from the change in the amplitude of the second measurement signal (ic, ic1, ic2) or of the second measurement signal (ic, ic1, ic2) transformed back into the rotor coordinates (d, q) information about the polarity of the permanent magnet flux with respect to the real axis (d) of the rotor coordinates (d, q) is obtained by the fact that - a decrease in the amplitude of the second measurement signal (ic, ic1, ic2) with the same polarity and - an increase in the amplitude of the second measurement signal (ic, ic1, ic2) occurs with opposite polarity.

Description

[0001] The invention relates to a method for detecting the rotational position of a rotor of a permanent magnet synchronous machine. The invention further relates to an arrangement for carrying out this method. State of the art

[0002] From the technical article by Joachim Holtz: “Initial Rotor Polarity Detection and Sensorless Control of PM Synchronous Machines”, Industry Applications Conference, 2006, 41st IAS Annual Meeting, Conference Record of the 2006 IEEE, vol. 4, pages 2040 to 2047, October 8-12, 2006, a method for determining the polarity or rotational position of a rotor of a permanent magnet synchronous machine at low rotational speed and at standstill or at start-up, and for controlling this permanent magnet synchronous machine without a rotational position sensor in these operating states, is known. Rotational position sensorless control of a permanent magnet synchronous machine can be carried out based on model-related estimation methods at rotational speeds above a limit of approximately 3% of the machine's rated rotational speed.At rotational speeds below this limit, measurement methods are required to estimate the rotor's position, which utilize the input of a measurement signal. These methods evaluate anisotropic properties of the permanent magnet synchronous machine, which result from the rotor's design or from the saturation of the stator iron core, the latter being the dominant cause in machines with magnets arranged on the surface of the rotor circumference.

[0003] DE 195 32 149 A1 discloses a method for correcting the flux direction of a model flux vector, generated by a machine model as a function of two state vectors of a sensorless, field-oriented rotating field machine, down to zero frequency, wherein a setpoint value is specified for the field-generating and torque-generating current components of the stator current vector of the rotating field machine, and wherein a current test vector with a time-varying profile is superimposed on the setpoint value for the field-generating current component, and a device for carrying out this method. According to the invention, the rotating field machine is controlled into the saturation range, and the response information of the rotor current vector, to which the test movement of the stator current vector is transferred, is recovered from the determined voltage vector of the rotating field machine.This provides a method that can correct the inaccuracy of the so-called voltage model at low frequencies down to zero frequency without interfering with the rotating field machine.

[0004] WO 1992 / 019 038 A1 discloses the determination of machine-related electromagnetic and mechanical state variables in electrodynamic induction machines, such as asynchronous, synchronous, and reluctance machines, powered by inverters. Due to advances in power and information electronics, these machines are gaining increasing importance in drive technology. In highly dynamic, field-oriented control systems, the rotor position must be determined so that the control algorithms can be executed. However, conventional determination methods have proven to be very unsatisfactory in this regard. The method utilizes the response of the measurement signals applied to the asynchronous machine. These are voltage jumps generated by the inverter, which cause current fluctuations. These fluctuations are then evaluated.The advantage of this method over prior art methods is that no mechanical encoder and no additional analog current sources are necessary, since the existing power converter serves as the measuring signal generator.

[0005] The publication "M. Schrödl: 'Sensorless control of the permanent-magnet synchronous machines at arbitrary operating points using a modified 'inform' flux model'" in European Transactions of Electrical Power, Volume 3, Issue 4, pages 277-283, July / August 1993, presents a new method based on the "inform" principle. This enables the control of permanent magnet synchronous motors without speed and position sensors. A special measurement method detects the electrical rotor angle using test signals generated by the inverter. The basic idea is to measure the different inductances in the direct and quadrature axes caused by saturation effects or the design. The sign of the magnetic flux is determined by shifting the magnetic setpoint with a specific armature current. Various methods for calculating the rotor angle from the measurement signals are presented.Measurements with a DSP-controlled drive verify the practical applicability of the new principle.

[0006] The input measurement signal is generally formed by a voltage superimposed on the input signal of a pulse-width modulator, which controls or regulates currents in the stator windings of the permanent magnet synchronous machine, also known as stator currents. This measurement signal is preferably an alternating signal with a frequency that differs from a fundamental frequency defining an operating point of the machine and is also referred to as the carrier. A carrier voltage forming such a carrier generates a carrier current and an associated magnetic flux density component in the machine. These signals are influenced by the anisotropic magnetic structures of the machine. The carrier current is easier to detect and is separated from the currents flowing at the fundamental frequency in the stator windings of the permanent magnet synchronous machine before further processing and evaluation.The differences in phase angle and amplitude between the carrier voltage and the carrier current contain information about the alignment to the anisotropy of the machine and are therefore analyzed by measurement methods referred to as standard procedures.

[0007] A particular challenge lies in measuring the rotor's position and the magnetic field's polarity while the machine is at rest, before the drive is started. This information is needed to enable a smooth, i.e., interference-free and, in particular, jerk-free, start-up of the drive. It is crucial to measure the initial rotor position and magnetic field polarity without generating an electromagnetic torque, as the machine will only maintain its original position until it is set in motion by the pulse-width modulator if this is done correctly.

[0008] According to the descriptions in the aforementioned technical article, the initial rotational position of the rotor is measured by detecting the spatial orientation of the machine's anisotropy when it is at rest, for which various methods are described. In one of these methods, a rotating carrier is applied. The resulting carrier current alters the saturation of the stator iron core if the axis of rotation of the carrier coincides with the axis of magnetization of the rotor. This induces a second harmonic in the carrier current, which is evaluated to detect the polarity of the magnetization. However, to determine the polarity of the magnetization, the carrier current must be large enough to cause a noticeable change in the saturation of the stator iron core.

[0009] In a second of these methods, an oscillating carrier with a time-varying spatial orientation is introduced. The excitation by the carrier current changes the saturation level when its direction coincides with that of the magnetic field. Here, too, second-order harmonics of the carrier current are generated, which can be used to identify the polarity. Optionally, a complete image of the carrier current can be recorded as the oscillating field is rotated along the circumference of the machine's air gap. Maximum and minimum amplitude values ​​determined in this way occur when the oscillating carrier is oriented along the d-axis, with the larger amplitude value indicating the direction of the positive d-axis. However, the detection of such a maximum is considered inherently inaccurate; a solution to this accuracy problem is not presented in the paper.

[0010] As further stated in the aforementioned technical article, most carrier-based methods have fundamental disadvantages, such as an insufficient signal-to-noise ratio, an undesirable dependence on parameters of the permanent magnet synchronous machine that may not be sufficiently precisely determinable, or insufficient measurement sensitivity. The latter necessitates the use of permanent magnet synchronous machines with buried magnets and highly anisotropic properties. Furthermore, periodic rotor position errors occur, which cannot be completely eliminated even with effective dead-time compensation methods. This results in torque oscillations whose frequency corresponds to six times the fundamental frequency of the permanent magnet synchronous machine.

[0011] The cited technical article describes a method for measuring the rotor's rotational position, in which an alternating voltage is injected as a carrier voltage into the winding system of a permanent magnet synchronous machine. The injection is based on prior knowledge of the spatial direction of an estimated rotor rotational position. The injected carrier voltage generates a carrier current and a spatial flux density distribution in the stator windings, both of which depend on the anisotropic conditions caused by the magnetic field. Their spatial directions therefore differ from the direction of the carrier voltage. This spatial deviation between the directions of the carrier voltage and the carrier current causes a phase shift between these quantities at the winding terminals of the permanent magnet synchronous machine. A higher-level control loop allows the injection angle to be varied to minimize the phase shift.The angle of the feed-in and the angle of the rotor's rotation then converge.

[0012] The cited technical article presents a signal flow diagram of a method and arrangement for controlling a permanent magnet synchronous machine, the elements of which are schematically simplified in Fig. 2 are reproduced. This in the Fig. Signal flow diagram 2, designated with reference numeral 300, relates to a vector-controlled drive of the permanent magnet synchronous machine, which is designated here with reference numeral 101. This drive is also referred to as field-oriented controlled. In this diagram, stator voltages are generated from an energy source 102, configured here as a three-phase AC voltage source or three-phase network, by means of a pulse width modulation 103 and a switching stage 104. These voltages are then supplied to the permanent magnet synchronous machine 101, thereby inducing stator currents in the machine. The stator currents are measured by a stator current measuring device 105, which is connected to the leads of the permanent magnet synchronous machine 101.The permanent magnet synchronous machine 101, energy source 102, pulse width control 103, switching stage 104 and stator current measuring device 105 are encompassed by a section 106 of the signal flow diagram 300 of the method and thus of the arrangement for controlling the permanent magnet synchronous machine 101, in which the signals are represented in stator coordinates.

[0013] The oscillating carrier voltage, in estimated rotor coordinates, is fed from a control stage 107 via a first line connection 108 to a first logic stage 109, where it is additively superimposed on a setpoint voltage supplied by a control stage 110 to form a total setpoint voltage. The control stage 110 and the first logic stage 109 are encompassed by a section 111 of the signal flow diagram 300 of the method, and thus of the arrangement for controlling the permanent magnet synchronous machine 101, in which the signals are represented in rotor coordinates. From the logic stage 109, the total setpoint voltage is fed to a first transformer stage 112, which is designed to transform the total setpoint voltage from the rotor coordinates into the stator coordinates. From the first transformer stage 112, the total setpoint voltage, thus transformed into the stator coordinates, is fed to the pulse width modulation 103.

[0014] In response to the applied carrier voltage, a carrier current is generated in the permanent magnet synchronous machine 101. This carrier current is superimposed on the stator currents, which drive the permanent magnet synchronous machine 101, and flows through the supply lines of the permanent magnet synchronous machine 101. It is measured by the stator current measuring device 105. From the stator current measuring device 105, the stator currents and the carrier current are supplied to a second transformer stage 113, which is designed to transform these currents from the stator coordinates into the rotor coordinates.

[0015] From the second transformer stage 113, the stator currents, transformed into rotor coordinates in this way, are fed to a second logic stage 114. There, they are superimposed on a current setpoint is, which is supplied to the second logic stage 114 via a second line connection 115. This current setpoint is subtracted from the current setpoint is. The current setpoint is is implemented as a signal that defines a target for the stator currents and thus for the torque to be delivered by the permanent magnet synchronous machine 101. The superposition, i.e., the difference, between the measured stator currents and the current setpoint is is fed to the control stage 110.

[0016] The control stage 107 is further configured to output a transformer control signal via a third line connection 116 to both the first transformer stage 112 and the second transformer stage 113. The transformer control signal includes information required for transforming between the rotor and stator coordinates about the angle of rotation between these coordinates, i.e., the rotational position of the rotor.

[0017] In Fig. Figure 1 schematically illustrates the relationship between the stator coordinates, labeled a and b, and the rotor coordinates, labeled d and q. Stator coordinates a, b and rotor coordinates d, q each form a Cartesian coordinate system. Both coordinate systems coincide at the origin and are rotated relative to each other by the angle e. The transform control signal thus includes information about the angle e. The rotor's orientation is symbolized by a schematic representation of a magnet 117. Furthermore, the diagram of Fig. Figure 1 shows a rotor axis 118. The permanent magnets arranged along the rotor circumference of the permanent magnet synchronous machine 101 produce a resulting permanent magnet flux in the rotor, the direction of which can be represented by a pointer. This pointer points radially outwards from the north pole of the permanent magnets embedded in the rotor. The axis or straight line along which this pointer is aligned is called the rotor axis 118. The position of the rotor is defined by the angle of the permanent magnet flux pointer.

[0018] In the signal flow diagram 300 in Fig. Section 7 of the cited technical article further describes the generation of the transformer control signal from the carrier current, which is measured and transformed into the rotor coordinates d, q by the second transformer stage 113. For this purpose, the stator currents, including the carrier current, which are transformed into the rotor coordinates d, q by the second transformer stage 113, are fed to a bandpass filter, which in Fig. Section 2 of the present application comprises control stage 107 and is not reproduced in detail. This bandpass filter serves to separate the measured and transformed carrier current from the stator currents. The carrier current, i.e., its phasor, is split into real and imaginary parts, where the real part of the carrier current represents the component in the direction of the axis of the rotor coordinates d, q, designated as the d-axis, whereas the imaginary part of the carrier current is its component in the direction of the axis of the rotor coordinates d, q, designated as the q-axis. From the real and imaginary parts of the carrier current, an angular difference is determined from an injection angle of the carrier voltage and a resulting displacement angle of the carrier current in the machine.From this angular difference, a mechanical angular velocity of the rotor is obtained by means of a PL controller and, through further integration, the transformer control signal is obtained, which is delivered via the third line connection 116 to both the first transformer stage 112 and the second transformer stage 113.

[0019] The PI controller also regulates the angle difference to zero, ensuring that the carrier voltage and carrier current are in phase and aligned along the d-axis of the rotor coordinate system. (See diagram of...) Fig. Figure 3 schematically illustrates this case. The vector of the carrier voltage is denoted by uc, that of the carrier current by ic, and a common oscillation center of the carrier voltage uc and carrier current ic is denoted by m; the common oscillation center m coincides here with the origin of the rotor coordinate system d, q as well as the stator coordinate system a, b.

[0020] According to further explanations in the cited technical article, it is considered important that the angle of rotation and the polarity of the rotor's magnetization be determined before commissioning the drive, and that no electromagnetic torque be generated during this determination process. Therefore, during this determination process, the current setpoint is supplied via the second line connection 115 is set to zero, while a low-amplitude carrier voltage is injected via the first line connection 108. This generates a carrier alternating current whose phasor points in an arbitrary direction. Consequently, a non-zero displacement angle is measured between the injected carrier voltage and the carrier current. This non-zero displacement angle activates the Fig. The control loop for position determination described in section 7 of the cited technical article brings the estimated rotational position of the rotor into agreement with the rotor axis 118 or one of the rotor axes in the case of a multipole rotor. The angle of rotation of the rotor estimated in this way either coincides with the direction of the magnetic flux or deviates from it by an angular error of half a period.

[0021] Due to the uncertainty in the estimated angle of rotation of the rotor, a further step is required to determine the polarity of the rotor's rotation. For this purpose, two short voltage pulses of opposite spatial direction are injected into the stator winding. These generate two resulting current pulses, the voltage pulses being chosen such that the resulting current pulses are at least equal to the nominal current amplitude of the machine. Since the current pulses are aligned along the d-axis of the rotor coordinates, they do not generate any torque.

[0022] Of these current pulses, one is oriented in the direction of the magnetic flux, thereby increasing the magnetization of the stator iron core and driving the inductance along the d-axis deeper into saturation. This inductance is thus reduced. The second current pulse is oriented in the opposite direction of the magnetic flux, reducing the saturation of the stator iron core and thus increasing the inductance. If the applied voltage pulses have the same volt-second values, the amplitudes of the current pulses will differ according to the inductances they affect. The current pulse with the higher amplitude then exhibits the positive direction of the rotor axis.

[0023] During the polarity determination process described above, the machine must remain stationary, and the supply of the alternating current carrier voltage is necessarily interrupted during this polarity determination interval. If the machine rotates during this process, the interruption of the carrier voltage risks a loss of information about the rotor's orientation. Furthermore, if the voltage pulses are not applied in the exact direction, torque surges may occur, posing a safety risk when operating a device driven by the machine, such as a vehicle. This can also cause undesirable and unpleasant acoustic effects, resulting in reduced comfort. Description of the invention: Problem, solution, advantages

[0024] The invention aims to improve a method of the described type for detecting the rotational position of a rotor of a permanent magnet synchronous machine in such a way that polarity determination can also be carried out when the rotor is rotating during operation, and the disadvantages described above, in particular the described safety risk and the aforementioned loss of convenience, are avoided. The invention further aims to provide an arrangement for carrying out this method.

[0025] This problem is solved by a method of the type mentioned above, in which a first measurement signal, designed as an AC signal, is provided in rotor coordinates, transformed into stator coordinates by a transform control signal, and fed into the permanent magnet synchronous machine. The first measurement signal, transformed into stator coordinates, generates a second measurement signal, also designed as an AC signal, in at least one stator winding of the permanent magnet synchronous machine. The second measurement signal is measured and transformed back into rotor coordinates by the transform control signal. An angular difference relative to the first measurement signal is obtained from the second measurement signal, transformed back into rotor coordinates. The transform control signal is then generated from this angular difference by PI control and subsequent integration. The transform control signal provides a measure of the rotor's rotational position.Furthermore, the angular difference is reduced to at least nearly zero by the pl control, thereby aligning the orientation of a real axis of the rotor coordinates with a rotor axis along which a resulting permanent magnet flux of the rotor, generated by permanent magnets enclosed by the rotor, is aligned. To determine the polarity of the permanent magnet flux with respect to the real axis of the rotor coordinates, at least one operating point setting signal is additively superimposed on the first measurement signal, causing a change in the amplitude of the second measurement signal.Information about the polarity of the permanent magnet flux relative to the real axis of the rotor coordinates is obtained from the change in the amplitude of the second measurement signal or the second measurement signal transformed back into the rotor coordinates, by the fact that a decrease in the amplitude of the second measurement signal occurs with the same polarity and an increase in the amplitude of the second measurement signal with opposite polarity.

[0026] In the method according to the invention, the transform control signal again contains information required for transforming between the rotor and stator coordinates about the angle of rotation between these coordinates, i.e., the rotational position of the rotor. Preferably, the first measurement signal is designed as an alternating voltage with a frequency that is high compared to those frequencies that occur in all stator currents flowing in the at least one stator winding during operation of the permanent magnet synchronous machine. Although the first measurement signal is, strictly speaking, an injection or control signal, the term "measurement signal" will be used throughout. The second measurement signal, generated as a reaction in the at least one stator winding of the permanent magnet synchronous machine, is preferably a current.

[0027] As in the method described in the aforementioned technical article by Joachim Holtz, the process of detecting the rotor's rotational position is also carried out in two sub-processes according to the invention. In the first of these sub-processes, the orientation of the real axis of the rotor coordinates is aligned with the rotor axis along which the resulting permanent magnetic flux of the rotor is oriented, caused by permanent magnets encompassed by the rotor. Thus, the position of the rotor axis is determined. This determines the position of the straight line along which the permanent magnetic flux of the rotor is oriented, whereby this alignment leaves open two possibilities in which of the two directions along the straight line the pointer, i.e., the field lines, of the permanent magnetic flux point or run. Therefore, a second sub-process follows the first, which serves to determine the direction of this pointer or...This field line serves this purpose. Within this description, this direction is also referred to as polarity.

[0028] In this second sub-process, which determines the polarity of the permanent magnet flux with respect to the real axis of the rotor coordinates, at least one preferably constant operating point setting signal is additively superimposed on the first measurement signal. This shifts the oscillation center not only of the first measurement signal but also of the second measurement signal along a characteristic curve that is nonlinear due to magnetic saturation effects in the stator material of the permanent magnet synchronous machine and describes the relationship between the second and first measurement signals. If the operating point setting signal, i.e., its vector, is aligned with the field lines or the phasor of the permanent magnet flux, the second measurement signal is shifted towards a region of higher saturation, thereby decreasing its amplitude. However, if the operating point setting signal, i.e., its vector, is oriented oppositely to the field lines or the phasor of the permanent magnet flux, the second measurement signal is shifted towards a region of higher saturation, thus decreasing its amplitude.Aligned with the pointer of the permanent magnet flux, the second measurement signal is shifted towards a region of lower saturation, thereby increasing its amplitude. From this change in the amplitude of the second measurement signal, which can be detected either before or after its inverse transformation into rotor coordinates, information about the polarity of the permanent magnet flux relative to the real axis of the rotor coordinates is thus obtained. This is because the amplitude of the second measurement signal decreases when the polarity is the same and increases when the polarity is opposite. This second step in detecting the rotor's rotational position can be performed in any operating state of the permanent magnet synchronous machine and is not dependent on its standstill.This also prevents jumps in torque or unwanted acoustic effects.

[0029] The invention thus enables a significant improvement in the operating behavior of the permanent magnet synchronous machine in a simple way and with little effort.

[0030] Advantageous embodiments of the method according to the invention are characterized in the dependent claims relating back to the independent method claim.

[0031] According to a preferred embodiment of the inventive method, the second measurement signal is superimposed on the stator currents drawn from an energy source, which supply energy to the permanent magnet synchronous machine for its operation. This is preferably achieved by feeding the first measurement signal in via the same device that controls the stator currents drawn from the energy source. The first measurement signal and control signals for controlling the stator currents, which can also be referred to as control signals for regulating the stator currents, are superimposed to form a combined control variable or manipulated variable that controls the stator currents in at least one stator winding of the permanent magnet synchronous machine.In response to the first measurement signal, a second measurement signal is generated in the permanent magnet synchronous machine. This second signal is superimposed on the stator currents that drive the machine and flows through the machine's supply lines. The second measurement signal, along with the stator currents, is then measured in a stator current measuring device. Alternatively, it is also possible to feed the signal exclusively into the permanent magnet synchronous machine as needed, i.e., when no stator currents are being fed in to drive the machine.

[0032] According to a further embodiment of the method according to the invention, the operating point setting signal is optionally fed in exclusively, or it is superimposed on a current setpoint that forms a target signal for controlling stator currents drawn from an energy source, through which energy is supplied to the permanent magnet synchronous machine for its operation, and / or on further setpoints derived from the current setpoint. According to this advantageous embodiment, it is possible to perform the measurement process both when the permanent magnet synchronous machine is at rest and during its operation, i.e., during rotation of the rotor. When the permanent magnet synchronous machine is at rest, in which the current setpoint is zero, only the operating point setting signal is fed in. When the measurement process is carried out during the operation of the permanent magnet synchronous machine, the current setpoint and the operating point setting signal are superimposed.Preferably, however, to perform the second sub-process of detecting the rotor's rotational position, the current setpoint is also set to zero when the rotor is rotating; in particular, this can be done by the higher-level control loop. Instead of the current setpoint, alternative setpoints, e.g., setpoints derived from the current setpoint, can also be fed in, such as control voltages for controlling current valves for stator currents. Preferably, the operating point setting signal is additively superimposed on the current setpoint or the setpoints derived from it and / or used alternatively. In each of these configurations, this sets a current operating point for the permanent magnet synchronous machine.

[0033] In another preferred embodiment of the method according to the invention, the operating point setting signal is fed in additively superimposed on the first measurement signal. In this alternative, the first measurement signal and the operating point setting signal are thus combined into a common measurement or control signal and the feed-in of the current setpoint or the setpoints derived therefrom and / or used alternatively remains unaffected.

[0034] In a further preferred embodiment of the method according to the invention, a polarity correction signal is superimposed on the transform control signal at the real axis of the rotor coordinates of opposite polarity of the permanent magnet flux, by which a rotation by an additional angle corresponding to the opposite polarity is taken into account during the transformation from rotor to stator coordinates and during the reverse transformation from stator to rotor coordinates.This polarity correction signal causes a rotation by an additional angle corresponding to the opposite polarity, both during the transformation from the rotor to the stator coordinates and during the reverse transformation from the stator to the rotor coordinates, which corresponds to half an electrical period of the permanent magnet synchronous machine, where such half an electrical period corresponds to one mechanical revolution of the rotor divided by the number of pole pairs of the permanent magnet synchronous machine.

[0035] The aforementioned task is further solved by an arrangement for detecting the rotational position of a rotor of a permanent magnet synchronous machine. This arrangement includes a control stage for providing a first measurement signal, configured as an alternating signal, in rotor coordinates. The arrangement further includes a first transformer stage for transforming the first measurement signal from the rotor coordinates into stator coordinates by means of a transformer control signal. A device for feeding the first measurement signal, transformed into stator coordinates, into the permanent magnet synchronous machine is also provided. A stator current measuring device serves to measure a second measurement signal, configured as an alternating signal, which is generated in at least one stator winding of the permanent magnet synchronous machine as a reaction to the first measurement signal, transformed into stator coordinates.Furthermore, a second transformer stage is provided for inverting the second measurement signal from the stator coordinates into the rotor coordinates using the transformer control signal. Bandpass filtering can also be applied. The control stage includes a device for deriving an angular difference from the first measurement signal, or a comparative measure proportional to the angular difference, from the second measurement signal inverted into the rotor coordinates. The control stage also includes a device for generating the transformer control signal from the aforementioned angular difference using PI control and subsequent integration, thus providing the transformer control signal as a measure of the rotor's rotational position.Furthermore, the control stage includes a device for controlling the angular difference by means of the PI control at least to nearly zero and thereby aligning the orientation of a real axis of the rotor coordinates with a rotor axis along which a resulting permanent magnet flux of the rotor, generated by permanent magnets encompassed by the rotor, is aligned. The arrangement for detecting the rotational position of the rotor also includes a device for superimposing at least one operating point setting signal additively to the first measurement signal, serving to determine the polarity of the permanent magnet flux with respect to the real axis of the rotor coordinates, such that the at least one operating point setting signal causes a change in the amplitude of the second measurement signal. An amplitude measuring device is provided for measuring the amplitude of the second measurement signal or the second measurement signal transformed back into the rotor coordinates.Finally, the arrangement for detecting the rotor's rotational position includes an evaluation unit for obtaining information about the polarity of the permanent magnet flux relative to the real axis of the rotor coordinates from the change in the amplitude of the second measurement signal. This information is obtained by observing that the amplitude of the second measurement signal decreases when the polarity of the permanent magnet flux is the same and increases when the polarity of the permanent magnet flux relative to the real axis of the rotor coordinates is opposite.

[0036] It should be noted that, depending on the design or configuration of the permanent magnet synchronous machine and its magnetic circuits, the relationship described above can be reversed, such that the amplitude of the second measurement signal increases with the same polarity and decreases with the opposite polarity of the permanent magnet flux relative to the real axis of the rotor coordinates. Accordingly, the evaluation device for obtaining information about the polarity of the permanent magnet flux relative to the real axis of the rotor coordinates must then be designed.

[0037] The device for feeding the first measurement signal, transformed into stator coordinates, into the permanent magnet synchronous machine is, in particular, a device that draws stator currents from an energy source, thereby supplying energy to the permanent magnet synchronous machine for its operation. Preferably, such a device is a pulse width modulation (PWM) controller with a downstream switching stage, which advantageously allows for speed and / or torque control of the permanent magnet synchronous machine in a manner known per se. The second measurement signal is then superimposed on the stator currents drawn from the energy source, which supply energy to the permanent magnet synchronous machine for its operation.

[0038] The second measurement signal, designed as an alternating signal, is measured with the stator current measuring device, in particular together with the stator currents through which energy is supplied to the permanent magnet synchronous machine for driving and to which the second measurement signal is superimposed.

[0039] Since the changes in the amplitude of the second measurement signal, which are to be evaluated to detect the polarity of the permanent magnet flux with respect to the real axis of the rotor coordinates, are independent of the back-transformation from the stator to the rotor coordinates, the amplitude measuring device is provided for measuring the amplitude of either the second measurement signal or the second measurement signal back-transformed into the rotor coordinates.

[0040] The arrangement according to the invention enables a considerable improvement in the operating behavior of the permanent magnet synchronous machine in a simple manner and with minimal equipment costs.

[0041] Advantageous embodiments of the arrangement according to the invention are characterized in the dependent claims relating to the independent arrangement claim.

[0042] In an advantageous embodiment of the arrangement according to the invention, a bandpass filter or a high-pass filter is connected upstream of the amplitude measuring device. Particularly in the case where the second measurement signal is superimposed on the stator currents by which energy is supplied to the permanent magnet synchronous machine for its drive and is measured together with these currents using the stator current measuring device, such a filter, inserted in the signal path upstream of the amplitude measuring device, both generally suppresses interference and specifically filters out the second measurement signal and suppresses that component of the measurement signal which represents the stator currents drawn from the energy source by which energy is supplied to the permanent magnet synchronous machine for its drive.

[0043] Another preferred embodiment of the arrangement according to the invention comprises a device for additively superimposing a current setpoint signal, which forms a target signal for controlling or regulating stator currents drawn from an energy source and through which energy is supplied to the permanent magnet synchronous machine for its operation, with the at least one operating point setting signal. This device is advantageously configured, for example, with a switching device via which either the current setpoint alone or the additive superposition of the current setpoint with the operating point setting signal can be switched. Another embodiment of the aforementioned device is implemented with a logic stage, here an adding stage, to whose inputs the current setpoint on the one hand and the operating point setting signal on the other can be supplied, the latter being selectively switchable off.

[0044] Another embodiment of the arrangement according to the invention is characterized by a device for additively superimposing the first measurement signal with the at least one operating point setting signal. This device is preferably designed with an additional logic stage, preferably an adding stage. Advantageously, in this logic stage, preferably an adding stage, the operating point setting signal, which is present in particular as a constant, is additively superimposed on the first measurement signal, which in particular has a sinusoidal waveform, in rotor coordinates. This sum is then transformed together into the stator coordinates and fed into the permanent magnet synchronous machine.

[0045] In a further preferred embodiment of the arrangement according to the invention, the evaluation device is configured to superimpose a polarity correction signal on the transform control signal at the real axis of the rotor coordinates where the polarity of the permanent magnet flux is opposite. This correction signal incorporates an additional rotation by an angle corresponding to the opposite polarity during the transformation from rotor to stator coordinates and during the reverse transformation from stator to rotor coordinates. This additional angle corresponding to the opposite polarity represents half an electrical period of the permanent magnet synchronous machine, i.e., one mechanical revolution of the machine's rotor divided by the number of its pole pairs.

[0046] The method according to the invention can be carried out with analog or digital signal processing circuit arrangements or with a computing circuit programmed with a sequence program, preferably a computer. Particularly in the latter case, the aforementioned problem is further solved according to the invention by a computer program product comprising program parts for executing a method of the type described and claimed above. Furthermore, the problem is solved by a machine-readable, in particular computer-readable, data structure generated by a method of the type described and claimed above and / or by at least one computer program product of the type described above.Finally, the above task is also solved by a machine-readable, in particular computer-readable, data carrier on which at least one computer program product of the aforementioned type is recorded and / or stored and / or on which at least one data structure of the aforementioned type is kept ready for retrieval. Brief description of the drawings

[0047] The drawing, in which matching elements in all figures are provided with the same reference symbols and a repeated description of these elements is omitted, shows: Fig. 1 schematically the relationship between stator coordinates and rotor coordinates of a permanent magnet synchronous machine, Fig. 2 a simplified signal flow diagram of a method and arrangement for controlling a permanent magnet synchronous machine according to the state of the art, Fig. 3 a schematically represented phasor diagram in which the carrier voltage and carrier current in a permanent magnet synchronous machine according to the state of the art are in phase and aligned along the d-axis of its rotor coordinate system, Fig. 4 a schematically represented phasor diagram in which displacements of the center of oscillation of a second measurement signal acting in different directions along a non-linear characteristic curve by an operating point setting signal cause the second measurement signal to assume different amplitudes, Fig. 5 a diagram illustrating the construction of an example of an arrangement according to the invention for detecting a rotational position of a rotor of a permanent magnet synchronous machine and illustrating the sequence of a method to be carried out with the arrangement for detecting the rotational position of the rotor, and Fig. 6 a modification of the diagram according to Fig. 5.

[0048] The embodiments of the invention shown in the drawing are described in more detail below. Preferred embodiment of the invention

[0049] In Fig. Figure 5 is a schematically depicted signal flow diagram of a first embodiment of a method and an arrangement according to the invention for controlling a permanent magnet synchronous machine 101, and is designated by reference numeral 100. This embodiment according to signal flow diagram 100 represents a modification of signal flow diagram 300 according to the one described in Figure 5. Fig. 2 represents the state of the art as shown, so that only the additional features compared to this will be described below.

[0050] The in Fig. The signal flow diagram 100 of the arrangement for detecting the rotational position of the rotor of the permanent magnet synchronous machine 101, shown in Figure 5, comprises a bandpass filter 119 or optionally a high-pass filter, to which an amplitude measuring device 120 is connected. The second measurement signal ic1, ic2 is fed from the stator current measuring device 105 either via the second transformer stage 113 after transformation from the stator coordinates a, b into the rotor coordinates d, q, or optionally directly in stator coordinates a, b to the bandpass filter 119, where it is freed from interference and from the measurement signal component that represents the stator currents drawn from the energy source, through which energy is supplied to the permanent magnet synchronous machine 101 for its drive. The specially filtered second measurement signal ic1, ic2 is fed to the downstream amplitude measuring device 120, in which the amplitude of the second measurement signal ic1, ic2 is measured.The amplitude measuring device 120 is in turn connected to a downstream evaluation device 121, to which the amplitude of the second measurement signal ic1, ic2 measured in the amplitude measuring device 120 is sent for evaluation.

[0051] Signal flow diagram 100 also includes a device for the additive superposition of an operating point setting signal to the first measurement signal uc. The operating point setting signal used here is a current ia, which is additively superimposed on the current setpoint is. For this purpose, a switching device 122 is connected upstream of the second line 115, via which either only the current setpoint is or the superposition of the current setpoint is with the operating point setting signal ia, i.e., in the form of an additively combined current setpoint is+ia, is supplied to the second line 115.

[0052] The operating point setting signal ia shifts the operating point, i.e., the oscillation center of the second measurement signal ic, along the nonlinear characteristic curve of the permanent magnet synchronous machine 101. This results in a change in the amplitude of the second measurement signal ic. Fig. Figure 4 of the diagram of stator coordinates a, b and rotor coordinates d, q schematically shows two examples of the formation of the second measurement signal ic, which oscillate around two different centers of oscillation mi1 and mi2 and are designated as second measurement signals ic1, ic2. These centers of oscillation mi1, mi2 are shifted in opposite directions along the rotor axis 118 relative to the origin of the coordinate systems. The second measurement signal ic1 with center of oscillation mi1 represents the effect of an operating point shift aligned with the polarity of the permanent magnet flux. The amplitude of the second measurement signal ic1 decreases there, as the operating point shift leads further towards saturation. In contrast, the second measurement signal ic2 with center of oscillation mi2 represents the effect of an operating point shift directed against the polarity of the permanent magnet flux.There, the amplitude of the second measurement signal ic2 increases, as the operating point shift leads out of saturation.

[0053] The amplitudes of the second measurement signal ic1 or ic2, which are changed by the input of the operating point setting signal ia, are measured in the amplitude measuring device 120. The measured values ​​are then fed to the downstream evaluation device 121 for evaluation. The evaluation device 121 is configured to obtain information about the polarity of the permanent magnet flux with respect to the real axis d of the rotor coordinates d, q from a change in the amplitude of the second measurement signal ic1, ic2 measured by the amplitude measuring device 120.Within the framework of the process step described above as the second sub-process of the inventive method for detecting the rotational position of the rotor of the permanent magnet synchronous machine 101, which serves to determine the polarity of the permanent magnet flux with respect to the real axis d of the rotor coordinates d, q, the polarity of the permanent magnet flux is determined in the evaluation device 121 from the effect of the operating point shift achieved with the respective fed-in operating point setting signal ia on the amplitude of the second measurement signal ic1, ic2 as that direction in which the feeding of the operating point setting signal ia results in a reduction of the amplitude of the second measurement signal ic1, ic2, i.e. in which the second measurement signal ic1 with the reduced amplitude occurs.

[0054] In other words, in the second step of the inventive method for detecting the rotational position of the rotor of the permanent magnet synchronous machine 101, the center of oscillation of the second measurement signal ic is described along the rotor coordinate d, i.e. the real axis in the diagram, by feeding the operating point setting signal ia in a predetermined direction. Fig. 4, shifted in one of the possible spatial directions, while the injection of the first measurement signal uc continues uninterrupted. If this injection of the operating point setting signal ia results in a decrease in the measured amplitude of the second measurement signal ic1, the center of oscillation mi1 has been reached, and thus the positive direction of the rotor coordinate d, i.e., the real axis, and therefore the polarity of the permanent magnet flux, has been determined. However, if this injection of the operating point setting signal ia results in an increase in the measured amplitude of the second measurement signal ic2, the center of oscillation mi2 has been reached, and thus the negative direction of the rotor coordinate d, i.e., the real axis, and therefore the direction opposite to the polarity of the permanent magnet flux, has been determined.

[0055] The evaluation unit 121 is equipped with a polarity correction signal output 123. If the permanent magnet flux has a polarity opposite to the real axis d of the rotor coordinates d, q, a polarity correction signal is output at this output 123. This signal is fed to a third logic stage 124, which is inserted into the third line connection 116 for the transformer control signal and serves to superimpose the polarity correction signal additively onto the transformer control signal. The polarity correction signal introduces an additional rotation by an angle corresponding to the opposite polarity during the transformation from rotor coordinates d, q to the stator coordinates a, b and during the reverse transformation from the stator coordinates a, b to the rotor coordinates d, q.The polarity correction signal causes a rotation by this additional angle, corresponding to the opposite polarity, both during the transformation from the rotor coordinates d, q to the stator coordinates a, b and during the inverse transformation from the stator coordinates a, b to the rotor coordinates d, q. This additional angle corresponds to half an electrical period of the permanent magnet synchronous machine 101, where this half electrical period corresponds to one mechanical revolution of the rotor divided by the number of pole pairs of the permanent magnet synchronous machine 101. The superposition of the transformer control signal and the polarity correction signal is then fed to the first transformer stage 112 and the second transformer stage 113.

[0056] Fig. Figure 6 shows a variation of the signal flow diagram 100 after Fig. 5 A further signal flow diagram 200 of a method and an arrangement for controlling a permanent magnet synchronous machine 101 in a second embodiment. In this embodiment, a modified operating point setting signal ua, now configured as an additional constant voltage, is fed in additively to the first measurement signal uc or to the setpoint voltage supplied by the control stage 110 via a fourth logic stage 125, so that this setpoint voltage, the first measurement signal uc, and the operating point setting signal ua are additively superimposed to form a total setpoint voltage. This arrangement enables the switching device 122 to be made of Fig. 5 is replaced. The second line connection 115 therefore only receives the set current value.

[0057] The operating point setting signal ua shifts the operating point, i.e., the oscillation center of the second measurement signal ic, along the nonlinear characteristic curve of the permanent magnet synchronous machine 101 in the same way as the operating point setting signal ia, which is implemented as a current. The same changes in the amplitude of the second measurement signal ic occur. The evaluation of the second measurement signal ic, or ic1, ic2, is thus carried out in the manner already described.

[0058] In summary, the invention provides a method and an arrangement for detecting the rotational position of a rotor of a permanent magnet synchronous machine, enabling polarity determination during rotor rotation and avoiding safety risks and loss of comfort. A first measurement signal in rotor coordinates is provided, transformed into stator coordinates by a transform control signal, and fed into the permanent magnet synchronous machine. As a reaction, a second measurement signal is generated in a stator winding of the permanent magnet synchronous machine, measured, transformed back into rotor coordinates by the transform control signal, and from this, the transform control signal, which forms a measure of the rotor's rotational position, is generated. A real axis of the rotor coordinates is then aligned with a rotor axis of a resulting permanent magnet flux of the rotor.A setting signal for the operating point is added to the first measurement signal, which changes the amplitude of the second measurement signal. Information about the polarity of the permanent magnet flux relative to the real axis of the rotor coordinates is obtained because like polarity causes a decrease and opposite polarity an increase in the amplitude of the second measurement signal.

[0059] The arrangement and method according to the invention advantageously achieve increased safety, robustness, and flexibility of the permanent magnet synchronous machine and its operation, since the rotor's rotational position can be determined even during rotation and not only when the permanent magnet synchronous machine is stationary. Increased safety and reduced component stress also result for arrangements connected to the permanent magnet synchronous machine, such as gearboxes, axle shafts, etc., because no voltage jump needs to be applied to the permanent magnet synchronous machine, and thus no torque jump can occur. This also prevents acoustic disturbances because there is no step response in the stator currents, i.e., no excitations with a high frequency bandwidth. Reference symbol list 100 Signal flow diagram of a method and arrangement for controlling a permanent magnet synchronous machine (first embodiment) 101 permanent magnet synchronous machine 102 Energy source (three-phase AC voltage source or three-phase network) 103 Pulse width control 104 switching stage 105 Stator current measuring device 106 range of 300, in which the signals are formed in stator coordinates 107 Control level 108 First line connection (for uc) 109 First linking stage 110 standard level 111 Range of 300, in which the signals are formed in rotor coordinates 112 First transformation stage for transforming the total target voltage from rotor to stator coordinates 113 Second transformation stage for transforming the stator currents from stator to rotor coordinates 114 Second linking stage 115 Second line connection (for is or is+ia) 116 Third line connection (for transformer control signal) 117 Magnet for schematic representation of the rotor orientation 118 Rotor axis 119 Bandpass filters (optionally: highpass filters) 120 Amplitude measuring device 121 Evaluation unit 122 Switching device between is and is + ia 123 Polarity correction signal output of 121 124 Third linking stage 125 Fourth linking stage 126 Fourth line connection (for operating point setting signal, etc.) 200 Signal flow diagram of a method and arrangement for controlling a permanent magnet synchronous machine (second embodiment) 300 Signal flow diagram of a method and arrangement for controlling a permanent magnet synchronous machine (state of the art) a stator coordinate b Stator coordinate d Rotor coordinate (real axis) e Rotation angle between stator coordinates and rotor coordinates ia Operating point setting signal IC carrier current / second measurement signal IC1 Carrier current / second measurement signal: Effect of an operating point shift aligned with the polarity of the permanent magnetic flux IC2 carrier current / second measurement signal: Effect of an operating point shift directed against the polarity of the permanent magnetic flux is the current setpoint m Common center of oscillation of uc and ic mi1 Center of oscillation of ic1 mi2 center of oscillation of ic2 q Rotor coordinate operating point setting signal uc carrier voltage / first measurement signal

Claims

[1] Method for detecting a rotational position of a rotor of a permanent magnet synchronous machine (101), wherein • a first measurement signal (uc) designed as an alternating signal in rotor coordinates (d, q) is provided, transformed by a transformer control signal to the transformer stage (112) in stator coordinates (a, b) and fed into the permanent magnet synchronous machine (101), • the first measurement signal (uc), transformed in stator coordinates (a, b) and formed by a carrier voltage (uc), generates a second measurement signal (ic, ic1, ic2) as a reaction in at least one stator winding of the permanent magnet synchronous machine (101), designed as an alternating signal and formed by a carrier current (ic, ic1, ic2). • the second measurement signal (ic, ic1, ic2) is measured and back-transformed into the rotor coordinates (d, q) by the transformer control signal to the transformer stage (113), • an angle difference to the first measurement signal (uc) is obtained from the second measurement signal (ic, ic1, ic2) which has been transformed back into the rotor coordinates (d, q), • the transform control signal is formed from the angle difference by PI control and subsequent integration, and the transform control signal forms a measure of the rotational position of the rotor, • through the PI control, the angle difference is further regulated at least almost to zero, thereby achieving an alignment of the orientation of a real axis (d) of the rotor coordinates (d, q) with a rotor axis (118) along which a resultant permanent magnet flux of the rotor caused by permanent magnets encompassed by the rotor is aligned, • to determine the polarity of the permanent magnet flux with respect to the real axis (d) of the rotor coordinates (d, q), at least one operating point setting signal (ia, ua) is additively superimposed on the first measurement signal (uc). • a change in the amplitude of the second measurement signal (ic, ic1, ic2) is caused by at least one operating point setting signal (ia, ua) superimposed on the first measurement signal (uc) and • from the change in the amplitude of the second measurement signal (ic, ic1, ic2) or of the second measurement signal (ic, ic1, ic2) transformed back into the rotor coordinates (d, q) information about the polarity of the permanent magnet flux with respect to the real axis (d) of the rotor coordinates (d, q) is obtained by the fact that - a decrease in the amplitude of the second measurement signal (ic, ic1, ic2) with the same polarity and - an increase in the amplitude of the second measurement signal (ic, ic1, ic2) occurs with opposite polarity. [2] Method according to claim 1, characterized by, that the second measurement signal (ic, ic1, ic2) is superimposed on stator currents taken from an energy source (102), through which energy is supplied to the permanent magnet synchronous machine (101) for its drive. [3] Method according to claim 1 or 2, characterized by , that the operating point setting signal (ia, ua) is optionally fed in exclusively or superimposed on a current setpoint (is) forming a target signal for controlling stator currents taken from an energy source (102) through which energy is supplied to the permanent magnet synchronous machine (101) for its drive, and / or further setpoints derived from the current setpoint (is). [4] Method according to claim 1 or 2, characterized by , that the operating point setting signal (ua) is fed in additively superimposed on the first measurement signal (uc). [5] Method according to one or more of the preceding claims, characterized by, that for the real axis (d) of the rotor coordinates (d, q) of opposite polarity of the permanent magnet flux, a polarity correction signal is superimposed on the transform control signal, by which a rotation by an additional angle corresponding to the opposite polarity is taken into account during the transformation from rotor (d, q) to stator coordinates (a, b) and during the inverse transformation from stator (a, b) to rotor coordinates (d, q). [6] Arrangement (100, 200) for detecting a rotational position of a rotor of a permanent magnet synchronous machine (101), comprising • a control stage (107) for providing a first measurement signal (uc) designed as an alternating signal and formed by a carrier voltage (uc) in rotor coordinates (d, q), • a first transformer stage (112) for transforming the first measurement signal (uc) from the rotor coordinates (d, q) into stator coordinates (a, b) by means of a transformer control signal to the transformer stage (112), • a device (103, 104) for feeding the first measurement signal (uc) transformed into the stator coordinates (a, b) into the permanent magnet synchronous machine (101), • a stator current measuring device (105) for measuring a second measuring signal (ic, ic1, ic2) designed as an alternating signal, formed by a carrier current (ic, ic1, ic2), which is formed by the first measuring signal (uc) transformed into the stator coordinates (a, b) as a reaction in at least one stator winding of the permanent magnet synchronous machine (101), • a second transformer stage (113) for inversely transforming the second measurement signal (ic, ic1, ic2) from the stator coordinates (a, b) into the rotor coordinates (d, q) by the transformer control signal to the transformer stage (113), • in the control stage (107) a device for obtaining an angle difference to the first measurement signal (uc) from the second measurement signal (ic, ic1, ic2) which has been back-transformed into the rotor coordinates (d, q), • in the control stage (107) a device for generating the transform control signal from the angle difference by PL control and subsequent integration, whereby the transform control signal forms a measure of the rotational position of the rotor, • in the control stage (107) a device for controlling the angle difference by the PI control at least to nearly zero and thereby causing an alignment of the orientation of a real axis (d) of the rotor coordinates (d, q) with a rotor axis (118) along which a resultant permanent magnet flux of the rotor caused by permanent magnets encompassed by the rotor is aligned, • a device (122, 125) for superimposing at least one operating point setting signal (ia, ua) additively on the first measurement signal (uc) in such a way that the at least one operating point setting signal (ia, ua) causes a change in the amplitude of the second measurement signal (ic, ic1, ic2), serving to determine the polarity of the permanent magnet flux with respect to the real axis (d) of the rotor coordinates (d, q), • an amplitude measuring device (120) for measuring the amplitude of the second measurement signal (ic, ic1, ic2) or of the second measurement signal (ic, ic1, ic2) transformed back into the rotor coordinates (d, q) and • an evaluation device (121) for obtaining information about the polarity of the permanent magnet flux with respect to the real axis (d) of the rotor coordinates (d, q) from the change in the amplitude of the second measurement signal (ic, ic1, ic2) by - a decrease in the amplitude of the second measurement signal (ic, ic1, ic2) with the same polarity and - an increase in the amplitude of the second measurement signal (ic, ic1, ic2) occurs with opposite polarity. [7] Arrangement (100, 200) according to claim 6, characterized by that a bandpass filter (119) or a highpass filter is connected upstream of the amplitude measuring device (120). [8] Arrangement (100, 200) according to claim 6 or 7, characterized by a device (122) for additively superimposing a current setpoint (is) forming a target signal for controlling stator currents taken from an energy source (102) through which energy is supplied to the permanent magnet synchronous machine (101) for its drive, with the at least one operating point setting signal (ia). [9] Arrangement (100, 200) according to claim 6 or 7, characterized by a device (125) for additively superimposing the first measurement signal (uc) with the at least one operating point setting signal (ua). [10] Arrangement (100, 200) according to one or more of claims 6 to 9, characterized by , that the evaluation device (121) is designed to superimpose a polarity correction signal on the transform control signal when the real axis (d) of the rotor coordinates (d, q) has opposite polarity of the permanent magnet flux, by which a rotation by an additional angle corresponding to the opposite polarity is taken into account during the transformation from rotor (d, q) to stator coordinates (a, b) and during the reverse transformation from stator (a, b) to rotor coordinates (d, q). [11] Computer program product comprising program parts for executing a method according to at least one of the preceding claims 1 to 5. [12] Machine-readable, in particular computer-readable, data structure, generated by a method according to at least one of claims 1 to 5 and / or by at least one computer program product according to claim 11. [13] Machine-readable, in particular computer-readable, data carrier on which at least one computer program product according to claim 11 is recorded and / or stored and / or on which at least one data structure according to claim 12 is kept available for retrieval.

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