阅读说明：本技术 调节旋转电流电机的方法和用于该方法的旋转电流机系统 (Method for regulating a rotating current machine and rotating current machine system for the method ) 是由 托马斯·沃尔班克 马库斯·福格尔斯贝格尔 马丁·巴赞特 于 2021-06-18 设计创作，主要内容包括：用于控制电动旋转电流机(3)的旋转电流机系统和方法,所述旋转电流机(3)特别是感应机(2),具有转子、定子和至少两个相绕组(U,V,W),其中,将至少一个电信号、特别是电压信号(U-(U,V,W)(t))施加到旋转电流机(3)的至少一个相绕组(U,V,W)上,优选的是施加到所有相绕组(U,V,W)上,并且测量所述至少一个相绕组(U,V,W)中的电流波形(i-(U,V,W)(t)),其中,使用互调信号分量(θ-(inter))来控制旋转电流机(3),互调信号分量(θ-(inter))是通过开槽效应和磁饱和效应在旋转电流机中感应的,并根据在所述至少一个相绕组(U,V,W)中测得的电流波形(i-((U,V,W))(t))确定。(Rotating current machine system and method for controlling an electric rotating current machine (3), in particular an induction machine (2), having a rotor, a stator and at least two phase windings (U, V, W), wherein at least one electrical signal, in particular a voltage signal (U, V, W), is fed U，V，W (t)) to a rotating current machine (3)At least one phase winding (U, V, W), preferably all phase windings (U, V, W), and measuring a current waveform (i) in the at least one phase winding (U, V, W) U，V，W (t)), wherein intermodulation signal components (θ) are used inter ) To control the rotating current machine (3), intermodulation signal components (theta) inter ) Is induced in the rotating current machine by the cogging effect and the magnetic saturation effect and is based on the current waveform (i) measured in the at least one phase winding (U, V, W) (U,V,W) (t)) determining.)

1. Method for controlling an electric rotating current machine (3), in particular an induction machine (2), the rotating current machine (3) having a rotor (21), a stator (20) and at least two phase windings (U, V, W), wherein at least one electrical signal, in particular a voltage signal (U, V, W), is fed_U，V，W(t)) is applied to at least one, preferably all, phase windings (U, V, W) of the rotating current machine (3) and the electrical signal waveform, in particular the current waveform (i) in the at least one phase winding (U, V, W), is measured or determined_U，V，W(t))，

Characterised by using intermodulation signal componentsTo control a rotating current machine (3), intermodulation signal componentsIs caused in the rotating current machine by a slotting effect and a magnetic saturation effect, the intermodulation signal components being determined by signal waveforms determined or measured in the at least one phase winding (U, V, W).

2. Method according to claim 1, characterized in that the inter-modulation signal components are passedDetermining the mechanical angular position (theta) of the rotor_mech(t)) and/or speed of rotation, and using said angular position (theta)_mech(t)) and/or the rotational speed.

3. Method according to claim 1 or 2, characterized in that the at least one signal waveform, in particular the current waveform (i), is dependent on_U，V，W(t)) to determine the intermodulation signal components

4. Method according to any of claims 1 to 3, characterized in that the current waveform (i) is determined in at least two phase windings (U, V, W), in particular in three phase windings (U, V, W), of the rotating current machine (3)_U,V,W(t)), in particular the rate of change (di) thereof_U,V,W(t)/dt) and applying the current waveform (i) by means of a mathematical equation_U,V,W(t)), in particular the rate of change thereof (di)_U,V,W(t)/dt) are combined together to form a combined signalAnd from the combined signalDetermining intermodulation signal components

5. Method according to claim 4, characterized in that the mathematical equation is an equation for calculating tensors, in particular space vectors.

6. Method according to any of claims 1 to 5, characterized in that the saturation signal component due to magnetic saturation effects in the rotating current machine (3) is eliminated by eliminating other signal components, preferably by eliminating the saturation signal componentAnd/or components of the slot signal due to the notching effectExtracting intermodulation signal components

7. Method according to claim 6, characterized in that the inter-modulation signal components are dependent onAngle (theta) of_inter(t)) by combining intermodulation signal componentsAngle (theta) of_inter(t)) and a saturated signal component contained in at least one of the signal waveformsAngle (theta) of_sat(t)) are combined to determine a groove angle (theta)_slot(t)), for example, the following calculation rule is applied:

θ_slot(t)＝±θ_sat(t)-θ_inter(t)。

8. a method according to claim 7, characterized by angling (θ) the grooves_slot(t)) divided by the number of slots of the rotor to determine the mechanical angular position (theta) of the rotor_mech(t))。

9. Method according to claim 7 or 8, characterized in that the intermodulation correction value (θ) is used_{inter_corr}) Correcting intermodulation signal components as a function of the rotational speed of the rotor (21) and/or the load, in particular the torque (M), on the rotating current machine (3)Angle (theta) of_inter(t))。

10. Method according to any one of claims 7 to 9, characterized by the aid of a saturation correction value (θ)_{sat_corr}) Correcting the saturation signal component as a function of the rotational speed of the rotor and/or the load, in particular the torque (M), on the rotating current machine (3)Angle (theta) of_sat(t))。

11. Method according to any of claims 1-10, characterized in that the electrical signal comprises an excitation signal (9), that the excitation signal (9) is essentially independent of the generation of the fundamental wave of the rotating current machine (3), and that the fundamental frequency of the excitation signal (9) is preferably at least five times, more preferably at least ten times, the temporal frequency of the fundamental wave of the voltage in the phase windings (U, V, W) used for generating the fundamental wave of the rotating current machine (3).

12. Method according to any of claims 1 to 11, characterized in that the electrical signal is a current signal, the response of the rotating current machine (3) to which is evaluated to determine the intermodulation signal componentMeasurement of

13. A rotating current machine system (1), comprising:

-a rotating current machine (3), in particular an induction machine (2), having a rotor, a stator and at least two phase windings (U, V, W);

-a converter (4) electrically connected to the rotating current machine (3), wherein the converter (4) is configured to convert an electrical signal, in particular a voltage signal (U)_U，V，W) To at least one phase winding (U, V, W), preferably to all phase windings (U, V, W), of a rotating current machine (3);

-at least one measuring device (8a, 8b) configured to measure or determine at least one electrical signal waveform, in particular a current waveform (i) in at least one phase winding (U, V, W)_U，V，W(t)),

It is characterized in that the preparation method is characterized in that,

-providing a control unit (12) configured to be based on intermodulation signal componentsTo control a rotating current machine (3), intermodulation signal componentsCaused by the effects of notching and magnetic saturation in the rotating current machine (3), the intermodulation signal componentIncluded in at least one measured signal waveform.

14. Rotating current machine system (1) according to claim 11, characterized in that the control unit (12) is integrated in the converter (4).

Technical Field

The invention relates to a method for controlling an electric rotating current machine, in particular an induction machine, having a rotor, a stator and at least two phase windings, wherein at least one electrical signal, in particular a voltage signal, is applied to at least one phase winding, preferably to all phase windings, of the rotating current machine, and the electrical signal waveform, in particular the current waveform, in the at least one phase winding is measured or determined.

The invention also relates to a rotating current machine system for carrying out such a method.

Background

In modern control methods of rotating current machines, it is often necessary to know the angular position of the rotor. To obtain this information, sensors such as incremental rotary encoders, absolute rotary encoders or resolvers may be used, which may be based on various physical principles. However, a disadvantage of all types of rotary encoders is the additional cost. In addition, the service life of rotary encoders is limited, often less than the projected service life of rotary current machines. Suspected failures of three-phase drives are typically due to failure of such sensors. However, malfunctions and down-times, such as those of a malfunctioning train on a railway line, may involve considerable effort and high costs and should therefore be avoided as much as possible.

In order to avoid the use of such sensors in rotating current machines or three-phase drives, so-called sensorless control methods have been developed, in which the angular position of the flow chain can be determined from the waveform of the electrical variables in the rotating current machine without the use of rotor angle or rotational speed sensors. In these processes, an excitation signal is typically applied by a transducer, and a response signal of the machine is measured as a result of the excitation signal. By means of a suitable evaluation, the angular position or the rotational speed of the rotor can be determined.

The sensorless control method utilizes the following facts: rotating current machines exhibit asymmetries due to their design or during operation due to electrical or magnetic effects, which can vary with time and position. A change in asymmetry usually results in a change in inductance and can therefore be detected, for example, by a change in the rise in current. Document WO99/39430a1 describes a sensorless control method.

One example of asymmetry associated with the design is the rotor of a permanent magnet excited synchronous machine (PSM), which has permanent magnets in certain locations that have a lower relative magnetic permeability than the surrounding ferrous areas, thus increasing the reluctance in the permanent magnet area relative to the ferrous areas. As the PSM rotor rotates, the reluctance along the circumference of the air gap varies with time and position, which appears as a change in inductance.

An example of an electrical or magnetic asymmetry is the local saturation phenomenon of the flux path in a rotating current machine.

The weaker the asymmetry relating to the rotor in the rotating current machine, the more difficult it is to detect a change in the rotation angle of the rotor without using a sensor. Determining the angular position of the rotor of an induction machine without using sensors (i.e. without using sensors of the type described above, such as incremental rotary encoders) is particularly difficult because induction machines have a lower asymmetry, especially compared to synchronous machines. In asynchronous machines, the slot signal components contained in the measured current waveform are usually isolated from other signal components and evaluated, or saturated signals are used. The slot signal component is due to the rotation of the rotor slots through the stator slots and the associated inductance variation. The slot signal component is typically small because the inductance change caused by the passing slot is relatively small, and therefore, depending on the operating state and design of the inductor, it may be difficult to identify and separate the slot signal component from other signals. Particularly as the inductor load increases, it is difficult or impossible to distinguish the slot signal component from other signal components.

Disclosure of Invention

In view of these comments, the object of the present invention is to alleviate or even completely eliminate the disadvantages of the prior art. In particular, it is an object of the present invention to provide a method of the above-mentioned type, in which the angular position and/or the rotational speed of the rotor of a rotating current machine (in particular an induction machine) can be determined in an improved manner by means of at least one electrical signal waveform and can be determined over a wide range of rotational speeds and loads.

This object is achieved by a method having the features of claim 1. Thus, according to the invention, provision is made for: in a method of the above-mentioned type, intermodulation signal components induced in the rotating current machine by slotting and magnetic saturation effects are used for controlling the rotating current machine, the intermodulation signal components being determined from the measured or determined electrical signal waveforms in said at least one phase winding. The intermodulation signal components may be used, inter alia, to determine the rotor position, i.e. the angular position of the rotor, which may then be used to control the rotating current machine. Preferably, at least one current waveform is measured or determined and used as the electrical signal waveform. For this reason, the following comments are directed to the measured current waveform. However, a measured or determined voltage waveform may also be used. The determination of the signal waveform, in particular the current waveform, in the at least one phase winding of the rotating current machine can be carried out, for example, by measuring the current and/or the voltage in the direct current link (intermediate circuit) of the converter, in the power supply of the converter or in the inlet terminals on the machine side of the converter. In particular, the phase current of the rotating current machine may be determined based on the intermediate circuit current. Since the method is particularly suitable for induction machines or electric machines having at least partially asynchronous machine-like characteristics (e.g. synchronous machines with damping cages), the following remarks are mainly directed to induction machines. In a preferred embodiment, the electric rotating current machine may have two, three or more than three phase windings. The electric rotating current machine is preferably a three-camera machine. The present invention is based on the following findings: as explained further below, there is a certain mathematical or physical relationship between the intermodulation signal components and the slot signal components indicative of the angular position or rotational speed of the rotor, and therefore, the control signals and position signals may be derived from the intermodulation signal components and used to control the rotating current machine. Thus, the slot signal components, which are often difficult to determine, no longer need to be used directly. The intermodulation signal components in the signal response of the rotating current machine in response to the excitation signal are significantly larger than the slot signal components in most operating conditions of the rotating current machine and, therefore, can be more easily identified and separated from other signal components. The intermodulation signal products may be evaluated in the time and/or frequency domain. In particular, the angular position and/or the rotational speed of the rotor may then be determined from the intermodulation signal components. For this purpose, saturated signal components may also be used and associated with intermodulation signal components (see below). Intermodulation signal components are mainly caused by the slot effect of the rotor or stator of the rotating current machine and by the magnetic saturation effect of the flux path in the rotating current machine. In most operating conditions, the intermodulation signal components have a different fundamental frequency than the notch signal components and the saturation signal components. The described effects in turn lead to separate signal components which are also contained in the at least one measured current waveform. The signal component in the current waveform that results from the rotor and stator slotting of the rotating current machine is referred to as the "slot signal component". The fundamental frequency of the slot signal component typically corresponds substantially to N times the rotational frequency of the rotor, where N corresponds to the number of slots of the rotor. The signal component induced in the current waveform, caused by the temporary and local changes in magnetic saturation of the magnetic flux path in the rotating current machine, is referred to as the "saturated signal component". The fundamental frequency of the saturated signal component generally corresponds substantially to twice the motor fundamental frequency or duty cycle. By physically combining the two effects mentioned above, their signal components in the rotating current machine are also combined, resulting in intermodulation signal components whose frequencies in most operating conditions are different from the frequencies of the saturated signal components and the frequencies of the tank signal components (intermodulation). The intermodulation effects described occur in particular in asynchronous machines and electric motors having at least partially asynchronous machine-like characteristics, which is why the method according to the invention is particularly suitable for controlling asynchronous machines. In previous applications known from the prior art, intermodulation signal components in the response of a machine to an excitation signal were considered to be interference components and cancelled. As already mentioned, the present invention is based on the following findings: there is a correlation between the intermodulation signal components and the slot signal components representing the angular position and speed of rotation of the rotor, and therefore the intermodulation signals are also suitable for controlling a rotating current machine. The relationship between the frequencies of the intermodulation signal component, the tank signal component and the saturation signal component is

ω_inter＝±ω_sta-ω_slot， (1)

Wherein, ω is_interIs the frequency, omega, of the intermodulation signal component_satIs the frequency of the saturated signal component, ω_slotIs the frequency of the bin signal component. ω in equation (1)_satThe sign of (c) depends on the construction and design of the rotating current machine. In order to recover the tank signal components from the intermodulation signal components by calculation, saturated signal components, preferably their fundamental frequencies, may be used in particular. The saturation signal component may be determined from the current in the phase winding of the rotating current machine. The mentioned signal components may also have harmonics in addition to the fundamental frequency, but these harmonics will be ignored for simplicity of explanation and because their influence is small. The invention is also based on the following findings: the correlation between the intermodulation signal components and the slot signal components may be used to determine the angular position and/or rotational speed of the rotor from the intermodulation signal components without the need to determine or use the slot signal components directly from the current waveforms. The intermodulation signal components can therefore be advantageously used in all control methods that require knowledge of the angular position of the rotor or the angular position of the flow chains. In contrast to the invention, in the prior art, intermodulation signals are usually cancelled as interference signals and the tank signal components or saturation signal components are used directly for control.

It is particularly advantageous if electrical signals, in particular voltage signals, are applied to all phase windings of the rotating current machine, and the current waveform produced by each phase winding is determined, in particular measured, evaluated and used for determining intermodulation signal components. The applied electrical signal may in particular comprise an excitation signal. The response of the machine to the excitation signal allows information to be obtained about the operating state of the machine, so that intermodulation signal components can be determined. Different types and shapes of excitation signals may be provided. The excitation signal may be, for example, a voltage signal, which is applied (anyway) to generate a rotating field in the air gap. The excitation signal may be the result of a switching operation of the power semiconductors of the converter, for example PWM (pulse width modulation) or similar methods. By switching operation, the converter generates a rotating field in the air gap. The excitation signal can then be integrated into the rotating field excitation. For example, the carrier frequency of the PWM or its harmonics may also be considered and used as the excitation signal. Parts of the switching sequence are then used to operate the rotating current machines and to determine and evaluate their current waveforms. The excitation signals can also be excitation signals or test signals which are independent of the switching sequence for generating the rotating field of the rotating current machine, are applied between the switching sequences for generating the rotating field in the air gap and/or are superimposed on them. Rectangular pulses are preferred as excitation signals because they can be easily generated using a transducer. The excitation signal may also be, for example, a sinusoidal, transient, pulsed, and/or rotating signal. The excitation signal itself may also be PWM modulated. The only important point is that the response of the machine to the excitation signal (e.g. current waveform) can be determined, which allows conclusions to be drawn about the aforementioned changes in the asymmetry of the rotating current machine. Preferably, when the applied excitation signals are not part of a switching sequence for operating a rotating current machine, i.e. are not used for generating a rotating magnetic field, the frequencies of the excitation signals are selected in such a way that they have no or minimal influence on the rotating field or torque generated in the air gap.

In a preferred embodiment, provision is made for: the angular position and/or the rotational speed of the rotor is determined by intermodulation signal components and is used for controlling the rotating current machine. For example, the rotational speed may be determined using equation (1). Thus, in determining the angular position and/or the rotational speed, the saturation signal component, in particular its angle or its angular representation, may be used. In one embodiment, the angular velocity ω is passed_slotBy integrating, the angular position of the rotor can be recovered by an inverse calculation. The angular position can be used in particular to indicate a physical quantity, in particular an electrical quantity, required for the regulation in the control method.

Preferably, the intermodulation signal components are determined by the at least one time current waveform, in particular its rate of change. After possible combination of multiple current waveforms of different phases, the corresponding rate of change can also be determined by mathematical equations.

Another embodiment provides that: in at least two phase windings, in particular in three phase windings, of a rotating current machine, current waveforms, in particular their rates of change, are determined and the current waveforms (preferably their rates of change) are combined by means of a mathematical equation, in particular an equation for calculating a space vector, to form a combined signal, and intermodulation signal components are determined from the combined signal. The measured current waveform is preferably a discrete time signal. However, the measured current waveform may also be a time-continuous signal. Instead of a current waveform, a voltage waveform may be used.

When determining the internal state of a rotating current machine, due to the electrical relationship

It is therefore convenient if the rate of change of the current waveform is combined by mathematical equations or combined to determine the rate of change of the combined signal, since this allows the asymmetry of the rotor angular position or speed to be assessed to be determined inter alia by the change in inductance, L, which is related to the voltage u (t) divided by the rate of change of current di (t)/dt. If the applied electrical signal is substantially a sinusoidal voltage signal, the measured current values, in particular the amplitude or RMS values, can also be used and combined substantially directly, since the relationship according to equation (2) reduces to a complex AC calculation

U(t)＝jωLI(t) (3)

Where U again represents voltage, j represents an imaginary unit, ω is angular velocity/frequency, L is inductance, and I is current. As equations for correlating the current waveforms, in particular their rate of change, it is possible to use equations for calculating space vectors, for example

Or

Wherein i_U,V,W(t) shows the current waveform (or di) in the phase winding U, V, W of the rotating current machine_U,V,W(t)/dt, the first time derivative thereof), j represents the unit of imaginary numbers, e represents the euler number, and pi represents the circle constant. In this case, the signals are combinedIs a complex vector, corresponding to a space vector. The space vectors are used to map physical quantities, in particular quantities of a polyphase system, in complex planes with real and imaginary parts. An intermodulation signal may then be determined from the combined signal.

In one embodiment, provision is made for: the intermodulation signal components are preferably extracted from the combined signal components by cancelling other signal components, preferably by cancelling saturation signal components due to magnetic saturation effects and/or slot signal components due to slot effects in the rotating current machine. In other words, intermodulation signal components are isolated. Other signal components may also be eliminated. The cancellation of signal components other than intermodulation signals may be performed by, for example, filtering. The cancellation may also be performed by subtracting unwanted signal components. For example, unwanted signal components in frequency, amplitude and phase may be estimated and then subtracted from the current waveform or associated current signal. This can be performed, for example, by prior Identification of the Machine and using a cost function, such as those described by w.fahrner, m.a.vogelberger and t.wolbank in "Identification and Compensation of High-order Harmonic Distortions in sensor Sensorless Control Based on Saliency" or the methods described by Brown, Ian patrerson and Robert d.lorenz in "Identification Machine Design method for Self-Sensing: balance of Saliency and Power Conversion Properties".

In one embodiment, provision is made for: by comparing the angle of the intermodulation signal component with the angle of the saturation signal component contained in the current waveform, for example by means of a calculation rule, depending on the angle of the intermodulation signal component

θ_slot(t)＝-θ_inter(t)±θ_sat(t) (5)

In combination, slot information, in particular slot angles, is determined.

Wherein, theta_slot(t) corresponding to the calculated groove angle, θ_inter(t) corresponds to the angle of the intermodulation signal component, and θ_sat(t) corresponds to the angle of the saturated signal component. The groove angle theta determined in this way_slot(t) substantially corresponds to the angle of the slot signal component. In other words, by combining the angle θ of the intermodulation signal components_inter(t) and angle θ of the saturated signal component_sat(t) determining or calculating the groove angle θ_slot(t) of (d). Angle theta_slot(t)、θ_inter(t) and θ_sat(t) may be the phase angle, in particular the phase angle of the fundamental frequency of the respective effect. Angle theta of the saturated signal component_sat(t) may be determined by doubling the angle of the stator current, wherein a load dependent offset value may be provided for correction. The offset value may be determined, for example, by a cost function derived from measurements of the rotating current machine.

For calculating the mechanical rotor angular position, provision can be made in one embodiment for: the mechanical angular position of the rotor is determined by dividing the slot angle by the number of slots of the rotor. Preferably, the number of slots corresponds to the total number of slots of the rotor.

During the experiments carried out using the method according to the invention it was found that: the angle of the intermodulation signal components may exhibit a deviation as a function of the rotational speed and/or load of the rotating current machine, such that the angular position of the rotor determined from the intermodulation signal components may deviate from the actual angular position. For this reason, it may be advantageous, for example, to correct the angle of the intermodulation signal components as a function of the load, in particular the torque and/or the rotational speed, of the rotating current machine using intermodulation correction values. The intermodulation correction values may be determined before applying the method, e.g. by measuring the machine or by calculation, and stored, e.g. in a table, or modeled by a mathematical function.

Furthermore, experiments have shown that the angle of the saturation signal component may also show a deviation as a function of the rotational speed and/or the load of the rotating current machine. For this reason, it can be specified that: the angle of the saturation signal component can be corrected using a saturation correction value as a function of the load, in particular the torque and/or the rotational speed, of the rotating current machine. The saturation correction value can be determined before applying the method, for example by measuring the machine or by calculation, and stored, for example, in a table, or modeled by a mathematical function.

In one embodiment it may be provided that: the electrical signal applied to the rotating current machine has an excitation signal which is substantially independent of a fundamental frequency component of the rotating field of the rotating current machine, the temporal fundamental frequency of the excitation signal preferably being at least five times higher, more preferably at least ten times higher, than the temporal frequency of the fundamental frequency of the voltage in the phase winding (U, V, W) used for generating the rotating field of the rotating current machine. Preferably, the excitation signal is a voltage signal. In another embodiment, the fundamental frequency of the excitation signal is at least twice the operating slip frequency of the induction machine. The excitation signal can also be generated by a sequence of substantially rectangular voltage pulses (step function), which can be formed either by several individual switching operations of the converter or by a combination of a plurality of individual pulses having a step-like and/or different duty cycles along the time axis.

In one embodiment, provision is made for: the electrical excitation signal is a current signal and the response of the rotating current machine, in particular the voltage over the rotating current machine, is evaluated to determine intermodulation signal components.

The above object is also achieved by a rotating current machine system according to claim 10. The three-phase system comprises:

a rotating current machine, in particular an induction machine, having a rotor, a stator and at least two phase windings;

a power unit, in particular a converter, which is electrically connected to the rotating current machine, wherein the power unit is configured to apply an excitation signal, in particular a voltage signal or a current signal, to at least one phase winding, preferably all phase windings, of the rotating current machine;

-at least one measuring device configured to measure or determine a time waveform, in particular a current waveform or a voltage waveform, of a machine response in at least one phase winding or in a dc link of the converter or in a power supply of the converter or in a machine side inlet port of the converter;

-a control unit configured to control the rotating current machine based on intermodulation signal components caused by slotting and magnetic saturation effects in the rotating current machine, which intermodulation signal components are comprised in the at least one measured current waveform, in particular in its rate of change.

The rotating current machine system is configured to perform the above-described method. Thus, with regard to advantages, technical effects and other features, reference is made to the above-described method. The power unit may generate the excitation signal by means of a switching operation. To this end, the power unit may comprise a plurality of electrical switches, for example semiconductor switches. The measuring means may comprise at least one current or voltage measuring sensor. Preferably, the measuring means can be used to determine the current waveform of all phases of the rotating current machine. For this purpose, a current measuring sensor can be provided in each phase winding of the rotating current machine. For m phase windings, it is also possible to provide current measuring sensors only in m-1 phase windings and to calculate the current of the m-th phase winding using the node rule.

The phase current of the rotating current machine may also be determined or calculated from measurements in the dc link of the converter, in the power supply of the converter or in the machine-side inlet side of the converter.

For example, the control unit may be a stand-alone unit or a part of another unit, in particular a microprocessor. The control unit may be integrated in the converter. The phase windings of the rotating current machine form coils or are connected to coils that can generate magnetic flux in the air gap between the rotor and the stator of the rotating current machine.

Drawings

Hereinafter, the present invention is described by referring to the drawings, but is not intended to be limited thereto.

FIG. 1 shows a schematic diagram of a rotating current machine system having a converter and a rotating current machine;

FIG. 2 shows a cross-sectional view of an induction machine;

FIG. 3A is a schematic diagram illustrating an exemplary excitation signal;

FIG. 3B shows a schematic current waveform (at different rotor positions) in response to the excitation signal according to FIG. 3A;

FIG. 4A shows a combined signal in the time domain resulting from the combination of the current waveforms of all the phase windings of the rotating current machine;

FIG. 4B shows the combined signal of FIG. 4A in the frequency domain;

FIG. 5 illustrates the real component of the combined signal;

fig. 6 shows the real components of the intermodulation signal components;

FIGS. 7A-7D illustrate different signal waveforms for the rotating current machine in its various operating states;

FIGS. 8A-8C each illustrate a waveform of a correction value;

FIG. 9 is a block circuit diagram as an example embodiment of the invention;

10A-10C illustrate the excitation signal and resulting current waveform.

Detailed Description

The method according to the invention is explained in further detail below on the basis of the application of an induction machine.

Fig. 1 shows a schematic diagram of a rotating current machine system 1, wherein a rotating current machine 3 is designed as an induction machine 2 driven by a converter 4, the converter 4 having a plurality of electronic switches (not shown), for example semiconductor switches. The converter 4 is configured to output a voltage at an output terminal 6 with a predetermined frequency, amplitude and (zero) phase angle by a suitable switching operation. The output 6 of the converter 4 is connected to the phase winding U, V, W of the inductor 2. Due to the voltage generated by the converter 4, a rotating magnetic field is generated in the air gap of the induction machine 2 between the rotor 21 and the stator 20 (see fig. 2), which induces a voltage in the rotor 21 of the induction machine 2 and rotates the rotor due to the generated rotor current.

The inductor 2 is schematically shown in fig. 1 as a circuit diagram. The inductor 2 has a three-phase winding U, V, W, and the three-phase winding U, V, W has a phase winding resistance R_U、R_V、R_WAnd phase winding inductance L_U、L_V、L_W. Voltage E_U、E_V、E_WRepresenting the voltage (back emf) induced in the stator 20 of the induction machine 2. Current I flowing in phase winding U, V, W_U、I_V、I_WThe current measurement sensor 7a and/or 7b of the measuring device 8a or 8b, respectively, can be used for measurement or determination. The phase currents may also be determined using a current measuring sensor 7b (e.g. based on the current flowing into the converter 4). It may be the case that a current measuring sensor 7a is provided in each phase winding U, V, W. The current measuring sensor 7a or 7b may be integrated into the converter 4 or may be a separate element. By means of the current measuring sensors 7a and/or 7b, the current I in the phase winding U, V, W can be determined_U、I_V、I_WTime domain current waveform i_U(t)、i_V(t)、i_W(t)。

Fig. 2 schematically shows a cross-section of an inductor 2 without windings, having a stator 20, a rotor 21, and slots 23 on each of the rotor 21 and the stator 20. For purposes of illustration, the angular position θ of rotor 21 is indicated_mech(t)。

As described above, the induction machine 2 exhibits an asymmetry that can vary as a function of time and position, thus allowing to obtain a reference to the angular position θ_mech(t) and/or information of the rotational speed of the rotor 21. One example of such asymmetry is slots 23 of rotor 21 and/or stator 20. Another example of asymmetry is saturation of the flux path in the inductor 2. Both these asymmetries lead to temporal and spatial inductance variations in the operation of the inductor 2, which can be evaluated by evaluating the current waveform i_U(t)、i_V(t)、i_W(t) is determined. For example, in a greatly simplified model illustrating asymmetry, it may be assumed, for example, that the phase winding isU, V, W three-phase winding inductance L_U、L_V、L_WAll have an average value L₀And as a mechanical angular position theta of the rotor 21_mechFunction of (t) in a sinusoidal manner (amplitude L)_M) Deviates from the average value L₀：

L_U(θ_mech(t))＝L_U，0+L_U，Msin(θ_mech(t)) (6A)

Angular position θ of rotor 21_mechThe variation in (t) thus also changes the inductance L_U、L_V、L_W. Therefore, the variable inductance component may also be referred to as a modulation inductance. Inductor L_U、L_V、L_WMay for example be caused by magnetic saturation of the slots 23 of the rotor 21 or stator 20 and/or the magnet path in the rotating current machine 3.

Determining the angular position θ of the rotor 21 of the induction machine 2 has hitherto been carried out_mech(t) is a significant challenge because: the inductor 2 has a much smaller asymmetry, in particular compared to most synchronous machines, and thus has much smaller inductance ripple in operation.

For determining the change in inductance, an electrical signal, preferably a voltage signal U, is applied_U(t)、U_V(t)、U_W(t) is applied to the phase winding U, V, W of the inductor 2 and the resulting current waveform i is measured using the current measuring sensor 7_U(t))、i_V(t)、i_W(t) of (d). The voltage or voltage pulse applied by the converter 4 to operate the induction machine 2 can be used as the voltage signal U_U(t)、U_V(t)、U_W(t) of (d). The electrical signal may comprise an excitation signal 9 for determining the operating state of the rotating current machine 3. The excitation signal 9 may be substantially independent of the rotating field of the rotating current machine 3Is generated. Here, an excitation signal 9 can be used, the excitation signal 9 being applied between the voltages (pulses) generated by the converter 4 for generating the rotating field or being superimposed on them. It is also possible to use a voltage waveform with a frequency higher than the frequency of the fundamental frequency component used for generating the rotating field.

In fig. 10A to 10C, the application of an exemplary excitation signal 9 and the resulting current waveform i in the phase winding U, V, W of the rotating current machine 3 is illustrated_U(t)、i_V(t)、i_W(t) of (d). Any ohmic resistance can be neglected here. FIGS. 10A-C show two switch positions of the transducer 4, with which a rectangular excitation signal 9 (amplitude V) with a positive voltage + U and a negative voltage-U can be generated by the transducer 4_DC). If, as shown in fig. 10B, an excitation signal 9 is applied which is shown in the upper partial image of fig. 10A as a function of time t, then in the current waveform i_U(t)、i_V(t)、i_W(t) obtaining the corresponding current increment di_U/dt、di_V/dt、di_WAnd/dt. In fig. 10B, the current waveform i for each phase winding U, V, W is shown_U(t)、i_V(t)、i_W(t) and the current slope di_U/dt、di_V/dt、di_WAnd/dt. The electrical equivalent circuit diagram of the inductor 2 with the voltages + U and-U of the applied excitation signal 9 is shown in the lower two images of fig. 10A. If the excitation signal 9 is applied with a positive voltage + U (with the electrical sign convention according to FIG. 1), then a positive current slope di_UThe first time/dt appears in the phase winding U (thus crossing the phase winding inductance L)_UPositive voltage drop) negative current slope di_V(dt or di)_WThe/dt appears in each phase winding V and W (thus across the phase winding inductance L)_VAnd L_WA negative pressure drop). The opposite is true for the negative voltage-U of the excitation signal 9.

Different phase winding inductances L as a result of asymmetries in the rotating current machine 3_U、L_V、L_WObtaining the current slope di_U/dt、di_V/dt、di_WAdditional deviation of/dt. This additional deviation is not shown in fig. 10B, but can be seen in fig. 3B.

In one embodiment, rectangular excitation signals 9, such as those shown in fig. 3A, are applied to the phase windings U, V, W of the inductor 2 to determine inductance. Fig. 3A shows the excitation signal 9 in normalized form. The excitation signal 9 may be applied, for example, between voltage pulses applied to generate a rotating field in the inductor 2, as a result of which excitation signal 9 a current slope di occurs in the phase winding U, V, W due to the relationship shown in equation (2)_U/dt、di_V/dt、di_WAnd/dt. Any ohmic resistance can generally be neglected here.

In fig. 3B, as an example, the different phase winding inductances L at different times and thus caused for the asymmetry of the rotating current machine 3_U(see equations 6A-6C), phase currents I in the phase winding U are shown_UThree different current slopes di_UAnd/dt. Similar illustrations apply to the remaining phase windings V and W. The illustration shown in the figures has been simplified in order to schematically illustrate the inductance determination principle. Current waveform i_U(t)、i_V(t)、i_W(t) variation with time allows to obtain information about the inductance L_U、L_V、L_WInformation of the change.

The current slope di in the phase windings U, V and W_U/dt、di_V/dt、di_WThe/dt is preferably determined at regular intervals and can then be combined into a combined signal using a mathematical equationHowever, it is also possible to use and combine the currents I, in particular in the case of a sinusoidal excitation signal 9_U、I_V、I_WI.e. amplitude or RMS value or instantaneous value. Preferably, the current waveforms are combined using mathematical equations that calculate space vectors, e.g.

Combined signalMay also be referred to as "significance signature". When the signal isWhen the calculation is performed as a space vector,representing a tensor.

FIG. 4A shows tensorsWherein the abscissa and the ordinate each represent a magnitude in amperes/second (a/s). Abscissa represents signalThe ordinate represents the imaginary part.

FIG. 4B illustrates the signal of FIG. 4A in the frequency domainWherein the abscissa plots the harmonic N of the signal_harmonisch. As can be seen from the view in figure 4B,containing three different signal components. The first significant signal component being the slot signal componentWhich is attributable to the slots 23 of the rotor 21 and the stator 20 of the rotating current machine 3. The second significant signal component being derived from the saturated signal componentWhich is attributable to saturation of the flux path in the rotating current machine 3. The third significant signal component being formed by intermodulation signal componentsFormation attributable to the slot signal componentAnd saturated signal componentAre interconnected. Component of slot signalSaturated signal componentAnd intermodulation signal componentsEach having a different fundamental frequency.

In the prior art, intermodulation signal components are present in sensorless control using slot informationAnd saturated signal componentPreviously cancelled as interference signal, slot signal componentFor determining the angular position and/or the rotational speed of the rotor. However, as can be seen from fig. 4B, in the present case, the bin signal componentRelatively small compared to other signal components. Therefore, it may be difficult to identify and extract the bin signal componentEspecially when the load of the rotating current machine 3 is higher. In FIG. 4B, the bin signal componentAlready having a signal component in common with the saturationHigher harmonic amplitudes of approximately the same order of magnitude.

According to the invention, provision is therefore made for: not directly using the slot signal componentTo control the rotating current machine 3, but using intermodulation signal componentsAnd indirectly included slot or rotor angle information to control the electric rotating current machine 2. The method according to the invention may be implemented in the control unit 12 (see fig. 1). Intermodulation signal componentIs thatThe main signal component of the signal over a wide range of rotational speeds can therefore be easily identified. The invention is based on the discovery that: intermodulation signal componentFundamental frequency and slot signal components ofThere is a relationship between the fundamental frequencies that allows information to be obtained about the angular position and/or rotational speed of the rotor 21. This relationship can be described by equation (1)

ω_inter＝±ω_sat-ω_slot， (1)

Wherein, ω is_interRepresenting intermodulation signal componentsFundamental frequency of (a) (. omega.)_satTo representSaturated signal componentFundamental frequency of (a) (. omega.)_slotRepresenting components of the slot signalOf the base frequency of (c). Omega_satDepending on the design and construction of the rotating current machine 3.

In order to determine the angular position of the rotor which can be used to control the rotating current machine 2, intermodulation signal components are generatedSeparate from the other signal components, namely: substantially isolated, for example by filtering, or the unwanted signal components are estimated and subtracted. Angle theta_inter(t) from the signalIn particular its fundamental frequency. The angle may be a phase angle that varies with time. This can be achieved, for example, using a PLL (phase locked loop). Furthermore, a saturated signal component is determinedAngle theta of_sat(t), in particular the phase angle, is determined, in particular, from its fundamental frequency. Calculating angle theta to obtain groove angle_slot(t) dividing the two angles theta_sat(t) and θ_inter(t) combined, e.g. using the equation

θ_slot(t)＝-θ_inter(t)±θ_sat(t) (5)

In the present disclosure, θ is used to refer to an angle, andrepresenting a signal or signal component. Groove angle θ determined by equation (5)_slot(t) is essentially a slot signal componentThe calculated angle of (c). By making the groove angle theta_slot(t) is divided by the number of rotor slots N, which can be in accordance with θ_slot(t) determining the mechanical angular position θ of the rotor 21_mech(t)。θ_mech(t) can then be used, for example, to control the rotating current machine 3. E.g. theta_mech(t) may be used to represent an electrical variable in the rotor reference frame or to control the angular position (angular position control) and/or the rotational speed (speed control) of the rotor.

FIG. 5 shows a combined current signal in secondsThe real component time waveform of (a). The signal containing a slot signal componentSaturated signal componentAnd intermodulation signal components

Fig. 6 shows intermodulation signal componentsIn seconds, wherein the channel signal componentAnd saturated signal componentHas been eliminated. However, the displayed signal still contains harmonics of its own and harmonics of other signal components.

Fig. 7A-7D show signal waveforms for different operating states of the induction machine 2 at different times. The time t in seconds is plotted on the abscissa in all of fig. 7A to 7D. Fig. 7A shows intermodulation signal componentsReal part 10 and imaginary part 11. FIG. 7B shows the mechanical rotational speed ω in revolutions per minute (rpm) of the rotor 21 over time_mech. Fig. 7C shows the torque generated by the rotating current machine 3 with respect to the nominal torque as a function of time. FIG. 7D shows the mechanical angular position θ of the rotor determined by the method according to the invention_mech(t) angular deviation θ from mechanical angular position in degrees determined using a rotary encoder_dev. In fig. 7D, it is evident that the method according to the invention can be used to determine the mechanical angular position θ of the rotor_mech(t) which shows a deviation from the actual (measured) mechanical angular position of less than 1 °.

Experiments have shown that by taking into account intermodulation signal componentsAngle theta of_inter(t) and saturated signal componentAngle theta of_sat(t) the accuracy of the method according to the invention can be further improved with regard to the dependency of the rotational speed and/or the load of the rotating current machine 3. It has been shown that intermodulation signal componentsAngle theta of_inter(t) and saturated signal componentAngle theta of_sat(t) may show a deviation as a function of the load, in particular the torque M, of the rotating current machine 3. In one embodiment, it can thus be provided that: by means of intermodulation correction values theta_{inter_corr}Intermodulation signal componentsAngle theta of_inter(t) is corrected as a function of the load, in particular the torque M, of the rotating current machine 3. Drawing (A)In 8A, theta in the rotating current machine 3 is shown_{inter_corr}The dependence on the torque M (in% relative to the nominal torque).

Provision may also be made for: saturated signal componentAngle theta of_sat(t) by means of saturation correction values theta_{sat_corr}The correction is made as a function of the load and the rotational speed of the rotating current machine 3, in particular the torque M. In FIG. 8B, θ in the rotating current machine 3 is shown_{sat_corr}The dependence on the torque M (in% relative to the nominal torque).

Intermodulation signal componentAngle theta of_interAnd possibly also on the rotational speed of the rotating current machine 3 (see fig. 8C). In addition to or instead of torque dependence, intermodulation correction values θ may be used_{inter_corr}To take this correlation into account.

Fig. 9 shows a schematic diagram of one possible embodiment of the method according to the invention. In the exemplary embodiment shown, the input variables used are intermodulation signal componentsElectrical angle theta_ele(t), torque M and mechanical angular velocity ω_mech。θ_ele(t) represents the angle of the fundamental component of the stator current and can be determined from the measured phase currents I_U、I_V、I_WDetermined, for example, as a space vector. Omega_mechMay be based on intermodulation signal componentsAnd (4) determining. By applying an electrical angle theta_ele(t) multiplied by a factor, preferably 2, to obtain a saturated signal componentAngle theta of_sat(t) which angle can be corrected by means of the saturation correction value theta determined previously_{sat_corr}A correction is obtained. By means of a phase-locked loop (PLL) signal processing unit, the intermodulation signal components can be determinedObtaining intermodulation signal componentsAngle theta of_inter(t) and by means of intermodulation correction values theta_{inter_corr}And (6) carrying out correction. By combining two angles theta_inter(t) and θ_sat(t), using equation (5) in particular, the groove angle θ can be calculated_slot(t) of (d). Calculating the groove angle theta in the UNWRAP block (spreading block)_slot(t) to give a coherent angular path (unwrapped phase) and then divided by the number of slots N of the rotor to obtain the mechanical angular position θ of the rotor_mech(t) of (d). The mechanical angular position can then be converted back again in the WRAP block (winding block) so that θ_mech(t) is expressed in angular intervals, in particular at [ -180 °; 180 degree]Or [0 °; 360 degree]Inter (wrapped phase). Then, θ can be used_mech(t) to control the rotating current machine 3.