Rotor position determination for multiple winding set generators

Abstract

There is described a method of observing a rotor position (18, 18 ') of a generator (5) comprising a plurality of sets of windings, the method comprising: applying a first high frequency signal (12) to a first set of windings; operating or controlling at least two of the sets of windings differently; measuring a first response (15); a first value (18) of the rotor position is determined based on the first response (15).

Description

Technical Field

[0001] The invention relates to a method of observing the rotor position of a generator comprising a plurality of winding sets and to a corresponding arrangement. Furthermore, the invention relates to a generator system and also to a wind turbine. Background Art

[0002] For controlling a generator (e.g. using vector control), the rotor position of the generator may be required. The generator may include multiple winding sets, which may be connected to corresponding individual converters. Conventionally, position estimation has been performed by high frequency injection (HFI) for zero or low speed operation. Other conventional methods may rely on the use of encoders for rotor position determination.

[0003] A concentrated winding fractional-slot generator may have a relatively low saliency ratio (q-axis inductance divided by d-axis inductance, where the d-axis and q-axis are defined in a synchronously rotating reference frame), which may make conventional position estimation very difficult.

[0004] It has been observed that the accuracy of the rotor position determination is not satisfactory in all cases or requires complex equipment.

[0005] Therefore, there may be a need for a method of observing the rotor position of a generator comprising a plurality of winding sets and a corresponding arrangement structure, wherein the accuracy and / or reliability of the rotor position determination is improved. There may also be a need for a generator system and a wind turbine capable of performing the method or implementing the method. Summary of the invention

[0006] This need is met by the subject matter according to the independent claim. Advantageous embodiments of the invention are described by the dependent claims.

[0007] According to an embodiment of the present invention, a method for observing the rotor position of a generator including multiple winding sets is provided, the method comprising applying a first high-frequency signal to a first winding set; operating or controlling at least two of the winding sets differently; measuring a first response; and determining a first value of the rotor position based on the first response.

[0008] The method may be performed, for example, by a generator controller or in particular a part or a module of a wind turbine controller.The method may be implemented in software and / or hardware.

[0009] The rotor position may be related to the electrical position of the rotor relative to the stator rotation of the generator. The electrical rotor position may be related to or may be proportional to the mechanical rotor position, which represents the circumferential angular position of the rotor. The electrical rotor position may be derived from the mechanical rotor position using a multiplication factor, which may depend on the number of poles. The generator may be a synchronous generator. The generator comprises a stator and a rotor. The generator may comprise a rotor at which a plurality of permanent magnets are mounted or the rotor may comprise an electromagnet.

[0010] The generator can be an integer slot generator or a fractional slot generator. The number of slots divided by the number of poles is an integer for an integer slot generator, but a rational number (not an integer) for a fractional slot generator.

[0011] The generator may include two, three, four, five, six, seven, eight or even more winding sets. The stator includes a plurality of teeth arranged in a circumferential direction with slots between the teeth. Some portions of the winding sets may be at least partially wound in the slots. Winding sets wound in different winding topologies such as concentrated winding topologies or distributed winding topologies may be supported.

[0012] In the case of a concentrated winding topology, a portion of a conductor of a winding set may be wound around a tooth such that the portion of the conductor occupies two immediately adjacent slots. In the case of a distributed winding topology, a portion of a conductor of a winding set may be arranged in two slots, wherein one or more other slots are circumferentially located between the two slots.

[0013] The embodiments of the present invention may be applied to a generator having a winding set with a concentrated winding topology, or may be applied to a generator having a winding set with a distributed winding topology.

[0014] Certain embodiments may be applicable to concentrated winding fractional slot generators.Despite a relatively low saliency ratio, the determination of the rotor position may be more accurate or more reliable than in conventional methods.

[0015] Embodiments of the present invention may provide high frequency injection for position estimation, which may rely on the saliency of the machine. Embodiments of the present invention provide several variants of high frequency injection, such as transient voltage vector injection, pulse width modulated signal injection, or continuous carrier signal injection. Thus, continuous carrier injection may include rotating sinusoidal signal injection in a stationary reference frame or pulsating sinusoidal signal injection in an estimated synchronous rotating reference frame. A specific embodiment of the present invention provides a pulsating sinusoidal signal injection on the d-axis (of a dq reference frame rotating at the fundamental electrical frequency of the generator) as high frequency injection. However, other embodiments may employ other HFI position estimation techniques.

[0016] The first high frequency signal may be a voltage signal or a current (signal) injected into the first winding set. The first high frequency signal may have a frequency higher than the fundamental frequency, for example between two and twenty times the fundamental frequency of the generator. Typically for position estimation using HFI, the frequency may be several hundred Hertz.

[0017] The first high frequency signal may be applied to the first set of windings by means of a converter connected to the first set of windings, ie to all wires of the first set of windings providing different phases.

[0018] The generator may include a first winding set and at least one second winding set. For one or more other winding sets other than the first winding set, the high frequency signal may not be applied at all or a corresponding high frequency signal different from the first high frequency signal may be applied. Differentially operating or controlling at least two of the winding sets may, for example, include not applying the high frequency signal to all winding sets, or applying different high frequency signals to at least two different winding sets.

[0019] Measuring the first response may include measuring a response current carried by a conductor in the first winding set or by a response current carried by one of the other winding sets or by several of the other winding sets. Preferably, the first response is measured as a current carried by the conductor in the first winding set. A first value of the rotor position may then be determined using the first response as feedback, for example by bandpass filtering and demodulating the response current. Thus, conventional methods may be applied to determine a first value of the rotor position based on the first response.

[0020] When at least two of the winding sets are operated or controlled differently, the reliability and / or accuracy of the rotor position determination can be improved. Embodiments of the present invention can take advantage of additional opportunities that exist when multiple winding sets are used in a generator. The additional opportunities can include that high-frequency signals can be injected in a manner that potentially improves the accuracy of the position estimate. Embodiments of the present invention can take advantage of the mutual coupling between the winding sets to enhance the ability of the position estimate using high-frequency injection. Embodiments of the present invention can provide improvements particularly during zero speed or low speed operation of the generator, and can also provide advantages particularly for winding sets having a concentrated winding topology.

[0021] According to an embodiment of the invention, applying the first high frequency signal to the first set of windings comprises injecting a first high frequency voltage, in particular a pulsating sinusoidal injection in the d-axis, into the first set of windings.

[0022] The injection of the first high frequency voltage may be performed by means of a converter connected to the free end of the first set of windings. The converter may be controlled by means of a voltage reference, the voltage reference comprising a high frequency part. The converter may comprise a plurality of controllable switches, which may be controlled via respective control signals provided to respective gates of the controllable switches. For controlling the generator, pulse width modulation (PWM) may be applied. Based on the voltage reference, the respective gate driver part may provide a pulse width modulation signal to (the gate of) the respective controllable switch, so that the desired first high frequency current is injected into or carried in the first set of windings.

[0023] According to an embodiment of the present invention, the first response is caused by a first high-frequency injection, and measuring the first response includes measuring a first current in a first winding set, wherein determining a first value of the rotor position specifically includes at least one of the following: bandpass filtering the measured first current; demodulating the measured and in particular filtered first current; performing polarity detection and position observation based on the demodulated current.

[0024] The injection of the first high frequency voltage precedes the measurement of the first current in the first set of windings, and they are typically performed within one control cycle, for example within a cycle of 0.4 ms. Additionally or alternatively, the response may also be measured in one or more of the other sets of windings, which may not have been applied with a high frequency signal or may have been applied with a different high frequency signal. In particular, in order to determine the rotor position or a first value of the rotor position, several response currents in several different sets of windings may be considered.

[0025] By a conventional transformation from a stationary frame to a synchronously rotating frame and using the estimated rotor position, the measured first current can be separated into d and q components. These d and q components will contain frequency components corresponding to the injected high frequency.

[0026] Bandpass filtering of the d current or q current can filter out current components that do not belong to the injected high-frequency signal. Therefore, bandpass filtering can attenuate the portion of the first current whose frequency is very different from the frequency of the first high-frequency injection signal. A demodulation process including a low-pass filter is applied to the d current or q current after bandpass filtering to extract the amplitude of each signal. They can be named as the demodulated d component or q component of the current. The demodulated q component can be used for the position observer and the demodulated d component can be used for the polarity detection module. Therefore, conventional equipment and methods can be supported and applied, thereby simplifying the method.

[0027] According to an embodiment of the present invention, injecting a first high-frequency voltage into a first set of windings comprises controlling a first converter connected to the first set of windings by adding an offset voltage (e.g., Vdhf) to a voltage reference, in particular in the d-axis of a coordinate system rotating at a fundamental electrical frequency, wherein the first high-frequency current in particular has a frequency higher than the fundamental frequency.

[0028] The offset voltage may be a high frequency offset voltage, which may be generated by a signal generator, in particular a high frequency injection generator, so as to generate a high frequency signal with a desired frequency, amplitude and phase. Therefore, a conventional converter may be used.

[0029] According to an embodiment of the present invention, differentially operating at least two of the winding sets includes: applying a high frequency signal to less than all winding sets; measuring a response to at least the winding set to which the high frequency signal is applied; and determining one or more values ​​of the rotor position based on the response.

[0030] For example, when the generator comprises exactly two winding sets, the first high frequency signal may be applied only to the first winding set, without applying any high frequency signal to the second winding set.Thereby the method may be simplified and the accuracy and / or reliability of position determination may be improved.

[0031] According to an embodiment of the present invention, differentially operating at least two of the winding sets includes: applying a second high frequency signal to the second winding set, the second high frequency signal being different from the first high frequency signal; measuring a second response; and determining a second value of the rotor position based on the second response.

[0032] The second high frequency signal may be different from the first high frequency signal in one or more characteristics, such as amplitude, frequency and / or phase. When the second high frequency signal is different from the first high frequency signal, the accuracy of the rotor position determination may be improved. The second response may involve measuring a second current in the second winding set. Additionally or alternatively, the second response may also be measured in, for example, the first winding set or another winding set different from the first winding set and the second winding set. According to a specific embodiment, measuring the second response and determining the second value of the rotor position based on the second response may be implemented in a manner similar to or the same as measuring the first response and determining the first value of the rotor position based on the first response.

[0033] According to an embodiment of the present invention, a high frequency signal can be applied to all winding sets and the high frequency signals can be different from each other. In addition, for each winding set, a corresponding response current can be measured as a response, and a corresponding value of the rotor position of this particular winding set can be determined based on the corresponding response measured in this winding set.

[0034] According to an embodiment of the present invention, a first winding set is capable of being connected to a first converter, wherein a second winding set is capable of being connected to a second converter, wherein, during injection of a first high-frequency voltage into the first winding set, the second winding set is disconnected from the second converter or the second winding set is connected to the second converter and the second converter does not operate or operates.

[0035] Thus, conventionally employed configurations may be supported. Thus, single set injection and single set operation as well as variants of single set injection and dual set operation may be supported, which may bring advantages in terms of accuracy and / or reliability of rotor position determination depending on the specific application and situation.

[0036] According to an embodiment of the present invention, the first high-frequency signal is different from the second high-frequency signal in at least one of the following characteristics: amplitude, frequency, phase.

[0037] Thus, multiple opportunities are provided to select a second high frequency signal that is different from the first high frequency signal.The first and second high frequency signals may differ in one or more of the characteristics listed above, which may bring advantages depending on the application and circumstances.

[0038] According to an embodiment of the invention, the first high frequency signal differs from the second high frequency signal in at least one first characteristic but is equal in at least one second characteristic, wherein the phases of the first and second high frequency signals differ substantially by Pi(π), wherein in particular the amplitude and frequency are equal.

[0039] When one or more of the characteristics are equal, the method of generating the corresponding signal may be simplified.The phase difference may depend on the specific configuration of the generator, for example, on whether the generator is a concentrated winding generator or a distributed winding generator.

[0040] According to an embodiment of the invention, the first high frequency signal differs from the second high frequency signal in all characteristics.Such an embodiment may be selected depending on the specific configuration of the generator.

[0041] According to an embodiment of the invention, a first high frequency signal is applied to the first set of windings in a time range, wherein a second high frequency signal is applied to the second set of windings in a time range. Thus, these signal injections may be applied simultaneously.

[0042] The application of injection and the measurement of response between sets are not exclusive.

[0043] According to an embodiment of the present invention, at least one of the following is true: the first and / or the second winding set has a concentrated or distributed winding topology; the generator is an integer or fractional slot generator; the generator has exactly two or four winding sets; the generator is a permanent magnet generator; the generator is a synchronous generator; each winding set provides multiple electrical phases, in particular three phases; the method is applied at low speed of the rotor of the generator, in particular between 0.0 and 0.2 times the rated speed.

[0044] Thus, different configurations and topologies of the generator can be supported. At relatively low rotation speeds, other position determination techniques may not be applicable due to insufficient reliability / accuracy.

[0045] It should be understood that the features disclosed, described, explained or provided, alone or in any combination, for the method of observing the rotor position of a generator may also be applied, alone or in any combination, to the arrangement structure for observing the rotor position of a generator according to an embodiment of the present invention, and vice versa.

[0046] According to an embodiment of the present invention, an arrangement structure for observing the rotor position of a generator including multiple winding sets is provided, the arrangement structure comprising: a control section, which in particular comprises multiple converters, each converter being capable of being connected to one of the winding sets, and the converter being suitable for applying a first high-frequency signal to the first winding set, differentially operating or controlling at least two of the winding sets; a measurement section, which is suitable for measuring a first response; and an evaluation section, which is suitable for determining a first value of the rotor position based on the first response.

[0047] The arrangement may be part of a controller, in particular a generator system controller or a wind turbine controller.The control section may in particular comprise respective converters, which may be able to connect or be connected to different sets of windings.

[0048] According to an embodiment of the invention, there is provided a generator system, in particular a generator system of a wind turbine, the generator system comprising a generator comprising a plurality of winding sets; an arrangement according to the preceding embodiments, which is connected to control the generator.

[0049] According to an embodiment of the present invention, there is provided a wind turbine including: a rotor at which a plurality of rotor blades are connected; and a generator system according to the aforementioned embodiment, a generator coupled to the rotor.

[0050] Embodiments of the present invention propose or include injecting high frequency signals into channels less than the total number of channels (winding sets) in all or part of the converter operation for position estimation of torque generation.

[0051] Embodiments of the invention may provide for injecting different high frequency signals (eg, different in one or more of amplitude / frequency / phase) into one or more of the winding sets (channels).

[0052] The aspects defined above and further aspects of the invention are apparent from the examples of embodiment to be described hereinafter and are explained with reference to the examples of embodiment.The invention will be described in more detail hereinafter with reference to examples of embodiment but to which the invention is not limited. BRIEF DESCRIPTION OF THE DRAWINGS

[0053] Embodiments of the present invention will now be described with reference to the accompanying drawings. The present invention is not limited to the embodiments shown or described.

[0054] Figure 1 schematically illustrates a wind turbine according to an embodiment of the invention;

[0055] Figure 2 schematically illustrates a portion of a generator system according to an embodiment of the present invention;

[0056] Figure 3 illustrates a graph relating to rotor position determination according to an embodiment of the present invention;

[0057] Figure 4 and Figure 5 The saliency ratios of different generators supported by embodiments of the present invention are illustrated. DETAILED DESCRIPTION

[0058] Figure 1 The wind turbine 1 schematically illustrated in comprises a rotor 2 at which a plurality of rotor blades 3 are mounted. The wind turbine 1 further comprises a generator system 4 according to an embodiment of the invention, wherein a generator 5 is coupled to the rotor 2 .

[0059] The generator system 4 comprises a generator 5 comprising a plurality of winding sets (which are not shown in detail). The generator system 4 also comprises an arrangement 6 according to an embodiment of the invention, which is connected to control the generator 5. Figure 1 In the illustrated embodiment, the arrangement 6 comprises substantially all elements except the generator 5, the rotor 2 and the rotor blades 3. In other embodiments, the arrangement 6 may be configured differently.

[0060] The arrangement 6 comprises a control section 7, which comprises a first control section 8 and a first converter 9 and a second control section 10 and a second converter 11. The control section 7 is configured to apply a first high frequency signal 12 to a first set of windings of the generator 5. The control section 7 is also configured to operate or control at least two of the sets of windings of the generator 5 differently. The arrangement 6 also comprises a measuring section 13, 14, which comprises a first current sensor 13 (and optionally at least one second current sensor 14), which is configured to measure a first response 15. The control section 7 also comprises an evaluation section implemented by a first evaluation section 16 (and optionally a second evaluation section 16'), which is suitable for determining a first value 18 of the rotor position based on the first response 15.

[0061] According to an embodiment of the invention, the arrangement 6 is configured to perform a method of observing the rotor position of the generator 5. Figure 1 In the embodiment illustrated in FIG. 1 , the first high frequency signal 12 is a first high frequency voltage, which is injected into the first set of windings of the generator 5. The first response 15 is a response caused by the first high frequency injection, and the first response is measured using the first current sensor 13 to measure the first current 15 in the first set of windings.

[0062] The first response 15 (Iabc) measured by the first current sensor 13 is received by the first control portion 8, in particular by the transformation module 19, which transforms the three-phase current Iabc into a current in the dq coordinate system rotating at the fundamental frequency of the generator. The transformation module 19 also separates the received current into a high-frequency component Iqhf and a substantially direct current portion Idq. The high-frequency component Iqhf is provided to the first evaluation section 16, called the HFI observer. The HFI observer 16 thus determines a first value 18 of the rotor position. This first value is also input to the transformation module 19 in order to correctly perform the transformation from abc to dq.

[0063] In order to inject the first high-frequency voltage 12 into the first winding set, the first converter 9 connected to the first winding set is controlled by adding an offset voltage Vdhf to a voltage reference Vd provided by a current controller 20 based on the current Idq received from the conversion module 19. The offset voltage Vdhf is a high-frequency signal and is added to the voltage reference Vd by an adding element 21, and the result is provided to the first controller 9 as a voltage reference (V1tot). The result of adding the offset voltage Vdhf to the voltage reference Vd generated by the first control part 8 is marked with the reference symbol V1tot and is provided to the first converter 9 as a reference voltage. Based on the voltage reference V1tot, the converter 9 causes the first high-frequency voltage 12 to be injected into the first winding set of the generator 5.

[0064] Figure 1A variant of differentially operating at least two of the winding sets of the generator 5 is illustrated, wherein a second high frequency signal 22 is also applied to a second winding set of the generator 5. Furthermore, a second response 23 is measured and a second value 18' of the rotor position is determined based on the second response 23. In particular, in the illustrated embodiment, the second response 23 is measured by a second current sensor 14 measuring the current in the second winding set. The second response 23 is received at the second evaluation part 10 of the control section 7, in particular at a further transformation module 19'.

[0065] It should be understood that the first control part 8 and the second control part 10 of the control section 7 may be configured substantially similarly or in the same manner, including the same or corresponding modules 19', 20', 16', 21', which may function or work similarly to the modules or parts explained with respect to the first control part 8. The result of adding the offset voltage V'dhf to the reference voltage V'd of the second control part 10 is called V2tot, which is provided to the second converter 11. Based on this voltage reference V2tot, the second converter 11 generates a second high frequency voltage 22 or causes the second high frequency voltage 22 to be injected into the second winding set of the generator 5.

[0066] During the injection of the first high frequency voltage 12, the second winding set may be disconnected from the second converter or the second converter 11 may not operate (also referred to as single set injection and single set operation). According to other embodiments, the second winding set may be connected to the second converter 11 and the second converter 11 may operate (also referred to as single set injection and dual set operation).

[0067] In other embodiments, when the first high frequency voltage 12 is injected into the first set of windings and the second high frequency voltage 22 is injected into the second set of windings, the corresponding voltages, in particular Vdhf and Vdhf', may differ in at least one characteristic such as amplitude, frequency or phase.

[0068] Figure 2 A portion of a generator system 4 according to an embodiment of the invention is schematically illustrated, wherein components for controlling at least one second winding set of the generator 5 are omitted. The portion of the generator system 4 comprises a first control portion 8 which can be connected to Figure 1 The first control section 8 shown in FIG. 1 is configured similarly or in the same manner. Figure 2, the first evaluation section 16 is illustrated in more detail. Based on the high frequency signal definition 25 regarding frequency, amplitude and phase, the generation module or high frequency injection generation module 26 generates a first high frequency signal in the form of a voltage offset Vdhf. This voltage offset Vdhf is added to the voltage reference Vd and the result is provided as a reference voltage V1tot to the first converter 11 performing pulse width modulation control. The first evaluation section 16 receives the first response 15 (Iabc) at the transformation module 19. After transforming the first response 15 into the dq system, the result (Idq) is received by a bandpass filter 27, which attenuates all parts of the current whose frequency is spaced apart from the frequency of the high frequency injection signal Vdhf. The filtered current is marked with reference numeral 28 and is received by a demodulator and low pass filter module 29. The demodulator 29 acts on the current of the d component and the q component respectively, and extracts the current amplitudes of the d component and the q component, thereby obtaining the demodulated signals of Idhf and Iqhf. The d component Idhf is provided to the polarity detection module 30 and the q component is provided to the position observer 31. The polarity detection module 30 obtains therefrom a polarity offset at an angle of 0 or π for polarity correction, depending on the response when a positive or negative Id current is provided. The position observer 31 calculates a first preliminary position 18a of the rotor position based on the input Iqhf in the phase locked loop. This generator angle is corrected by adding the polarity offset 32 ​​output by the polarity detection module 30 and provided to the transformation module 19 in order to correctly perform a dwell transformation from the current response Iabc (reference numeral 15) to a corresponding value in the dq system. Figure 1 Similarly, the second set of windings of the generator 5 may also be provided with a corresponding second high frequency current 22, from which a second response 23 is measured.

[0069] In conventional methods, in a dual system concentrated winding generator, HFI would involve injecting the same high frequency signal into both winding sets simultaneously and observing the effect in the current. However, according to an embodiment of the present invention, different winding sets use different injection currents, with different amplitudes, frequencies and / or phases for each of the systems.

[0070] It has been observed from simulation and experimental results that, at least for concentrated winding generators, using the same injection signal for several winding sets, at least the position estimation may be inaccurate. The configuration of the injection scheme according to an exemplary embodiment is shown in Table 1 below:

[0071] Table 1:

[0072]

[0073] The simulation results are Figure 3 is provided, Figure 3In a coordinate system having a horizontal axis 33 representing the angle error and a vertical axis 34 representing the feedback response Iqhf of the injected high-frequency signal, there are illustrated: curve 35, which represents the operation of the dual converter and the injection of anti-phase (phase shift π, as shown in Table 1 above) high frequency into the first winding set and the second winding set; curve 36, which represents that when the first high-frequency current is injected into the first winding set, the converter operation is reduced (only the first converter 9 operates and is connected to the first winding set); curve 37, which represents the operation of the dual converter and the injection of high-frequency current only in the first winding set, and; finally, curve 38, which represents the operation of the dual converter when the high frequency is injected into the first winding set and the second winding set (no phase shift).

[0074] from Figure 3 From the curves in , it can be concluded that the higher the amplitude Iqhf (which is used as feedback for speed estimation and angle regulation), the higher the sensitivity of the control is observed. Figure 3 It can be found that for concentrated winding generators, the standard method of injecting equal HFI into both winding sets (curve 38) is the worst for position estimation. This is probably because in this type of generator, the mutual coupling between the systems is positive and applying equal injection will have a cancelling effect.

[0075] Both double converter operation (standard operation of current direct drive generators) injecting HFI into one winding set (curve 36) and injecting HFI into both winding systems in reverse phase (curve 35) show a significant improvement in position estimation accuracy. This estimation technique can also be used for reduced converter operation (curve 37) operating only one system, i.e., for example, only the first converter 9 is connected and operates with the first winding set. The mutual coupling effect between the two winding sets again makes a difference. In the reduced operation of the converter (curve 37), there is no cancellation effect; for the reverse injection of HFI into both winding systems (curve 35), there is an additive effect from the coupling; for the injection of HFI into one winding set (curve 36), the coupling effect is partially added.

[0076] In other embodiments, the injection scheme shown in Table 1 may involve using different frequencies and / or voltage amplitudes between two or more injection signals.

[0077] In an alternative embodiment, the existing HFI method can be used to apply the same injection to multiple systems, especially for distributed winding generators. This is because in this type of generator, the mutual coupling between the systems is negative and the same injection can be better than a single system injection and better than an anti-phase injection, which may be desirable for concentrated winding topology generator designs.

[0078] Figure 4 and Figure 5The saliency ratio of a distributed winding generator (curve 41) and a concentrated winding generator (curve 42) is illustrated in a coordinate system with generator torque as coordinate 39 and saliency ratio as coordinate 40. The concentrated winding fractional slot generator has a relatively low saliency ratio. It is obvious that the saliency ratio is significantly lower in the case of a concentrated winding generator compared to a distributed integer slot generator, especially at lower load levels.

[0079] It should be noted that the term "comprising" does not exclude other elements or steps and "a" or "an" does not exclude a plurality. Furthermore, elements described in association with different embodiments may be combined. It should also be noted that the reference numerals in the claims should not be interpreted as limiting the scope of the claims.

Claims

1. A method for observing the rotor position (18, 18') of a generator (5) comprising a plurality of winding sets, the method comprising: include: applying a first high frequency signal (12) to the first set of windings; differentially operating or controlling at least two of said sets of windings; measuring a first response (15); A first value (18) of the rotor position is determined based on the first response (15).

2. The method according to the preceding claim, in, Applying the first high frequency signal to the first set of windings includes: A first high-frequency voltage (12) is injected into the first set of windings, in particular by means of a pulsating sinusoidal injection in the d-axis.

3. The method according to any one of the preceding claims, in, The first response (15) is caused by the first high frequency injection (12), and measuring the first response comprises measuring a first current (15) in the first set of windings, Therein, determining the first value (18) of the rotor position comprises in particular at least one of the following: transforming the measured first current (15) into a transformed first current (Idq) in a synchronously rotating dq system; performing bandpass filtering (27) on the measured first transformed dq current (Idq); Demodulating (29) the measured and, in particular, bandpass filtered first current; Polarity detection (30) and position observation (31) are performed based on the demodulated currents (Idhf, Iqhf).

4. The method according to any one of the preceding claims, in, Injecting the first high frequency current (12) into the first winding set comprises: controlling a first converter (9) connected to said first set of windings by adding a high frequency offset voltage (Vdhf) to a voltage reference (Vd), in particular in the d-axis of a coordinate system rotating at a fundamental electrical frequency, Therein, the first high-frequency voltage particularly has a frequency higher than the fundamental frequency.

5. The method according to any one of the preceding claims, in, Differentiatingly operating at least two of the winding sets includes: applying a high frequency signal to less than all of the winding sets; measuring a response of at least the set of windings to which a high frequency signal is applied; One or more values ​​of the rotor position are determined based on the response.

6. The method according to any one of the preceding claims, in, Differentiatingly operating at least two of the winding sets includes: applying a second high frequency signal (22) to a second set of windings, the second high frequency signal being different from the first high frequency signal (12); measuring a second response (23); A second value (18') of the rotor position is determined based on the second response (23).

7. The method according to any one of the preceding claims, in, The first set of windings is capable of connecting or being connected to a first converter (9), wherein the second winding set is capable of connecting or being connected to a second converter (11), During the injection of the first high frequency voltage (12) into the first winding set, the second converter (11) does not operate or the second winding set is connected to the second converter (11) and the second converter (11) operates.

8. The method according to any one of the preceding claims, in, The first high-frequency signal (12) and the second high-frequency signal (22) differ in at least one of the following characteristics: Amplitude; frequency; Phase.

9. The method according to any one of the preceding claims, in, The first high frequency signal (12) is different from the second high frequency signal (22) in at least one first characteristic, but is equal to the second high frequency signal (22) in at least one second characteristic, Therein, the first and second high-frequency signals differ in phase by essentially π, wherein in particular the amplitude and the frequency are equal.

10. The method according to any one of the preceding claims, in, The first high-frequency signal (12) and the second high-frequency signal (22) are different in all characteristics.

11. The method according to any one of the preceding claims, in, The first high frequency signal (12) is applied to the first set of windings during a time range, The second high frequency signal (22) is applied to the second winding set during a time range.

12. The method according to any one of the preceding claims, in, At least one of the following is true: The first and / or second winding sets have a concentrated or distributed winding topology; The generator (5) is an integer or fractional slot generator; The generator (5) has a plurality of winding sets, in particular exactly two or four winding sets; The generator (5) is a permanent magnet generator; The generator (5) is a synchronous generator; Each winding set provides a plurality of electrical phases, in particular three phases; The method is applied at low rotational speeds of the rotor of the generator, in particular between 0.0 and 0.2 times the rated rotational speed.

13. An arrangement (6) for observing the rotor position (18, 18') of a generator (5) comprising a plurality of winding sets, the arrangement include: A control section (7) comprising in particular a plurality of converters (9, 11), each converter being connectable to one of the sets of windings, the converters (9, 11) being adapted to: applying a first high frequency signal (12) to the first set of windings; differentially operating or controlling at least two of said sets of windings; A measuring section (13, 14), wherein the measuring section (13, 14) is suitable for: measuring a first response (15); An evaluation section (16, 16'), the evaluation section (16, 16') being adapted for: A first value (18) of the rotor position is determined based on the first response (15).

14. A generator system (4), in particular a generator system of a wind turbine, the generator system (4) include: A generator (5) comprising a plurality of winding sets; An arrangement (6) according to the preceding claim, connected to control the generator.

15. A wind turbine (1) comprising: include: A rotor (2) to which a plurality of rotor blades (3) are connected; According to the generator system (4) of the preceding claim, the generator (5) is coupled to the rotor (2).

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