Device for detecting an event signal at high frequency in a rotating electrical machine

Abstract

The invention relates to a device (4) for detecting high-frequency event signals in a rotating electrical machine (2), wherein at least two sensors (28) for detecting low-frequency sensor signals are arranged in the rotating electrical machine (2), and wherein the at least two sensors (28) each comprise an antenna for decoupling high-frequency event signals from the high-frequency electromagnetic field of the rotating electrical machine (2). In order to achieve a simple and inexpensive embodiment compared to the prior art, it is proposed that the sensors (28) are connected to a common HF evaluation device (38) via a common, in particular reactive, coupling element (36), wherein the common coupling element (36) is configured to transmit high-frequency event signals from at least one of the sensors (28) to the common HF evaluation device (38) and to decouple low-frequency sensor signals.

Description

Technical Field

[0001] The present invention relates to a device for detecting high-frequency event signals in a rotating electrical machine.

[0002] Furthermore, the present invention relates to a method for detecting high-frequency event signals in a rotating electrical machine.

[0003] Furthermore, the present invention relates to a control unit having means for performing such a method.

[0004] Furthermore, the present invention relates to a computer program for performing such a method when running in a control unit.

[0005] Furthermore, the present invention relates to a computer program product having a computer program.

[0006] Furthermore, the present invention relates to a rotating electrical machine having at least one such device for detecting high-frequency event signals. Background Art

[0007] Such devices are used, for example, in high-voltage rotating electrical machines, in particular high-voltage motors and high-voltage generators, which can be operated with a voltage of at least 1 kV.

[0008] For example, high-frequency event signals can be understood as pulse signals in the frequency range from 100 kHz to 100 MHz. The pulses have a rectangular, Gaussian or other pulse shape. Such high-frequency event signals are formed, for example, in the case of partial discharges that often occur in rotating electrical machines. Partial discharges are, for example, local discharges caused by inhomogeneities in the insulating material and lead to the failure of the insulation in the long term and thus to the failure of the high-voltage machine. Therefore, high-voltage rotating electrical machines are regularly checked for partial discharges. In particular, when the frequency of partial discharges changes significantly, the cause needs to be found. In particular, in larger rotating electrical machines, partial discharges can only be identified with limited space. Therefore, multiple sensors are evaluated to achieve as seamless a monitoring as possible.

[0009] Patent document EP 0 662 220 B1 describes a method for decoupling high-frequency event signals from a high-frequency electromagnetic field in a large electrical machine, which large electrical machine has a support carrying an electrical winding and equipped with at least one temperature probe. The high-frequency event signals can be received from the temperature probe used as an antenna. In this way, the cost of the device for decoupling the event signals is kept low, and when a large number of temperature probes are used, the damage causing the event signals can be located.

[0010] The published document EP 3 570 052 A1 describes a method for measuring the high-frequency event signals, in particular partial discharges, of pulses in a rotating electrical machine. In order to achieve a simple and inexpensive implementation compared to the prior art, it is proposed that during the operation of the rotating electrical machine, the event signals are decoupled from the high-frequency electromagnetic field by means of a sensor, wherein a pulse-shaped low-frequency envelope signal is determined from the decoupled event signals by means of a high-frequency detector circuit, and wherein the event signals are detected when the amplitude of the envelope signal exceeds a threshold value. Summary of the Invention

[0011] The object on which the present invention is based is to provide a device for detecting high-frequency event signals in a rotating electrical machine, which device can be implemented simply and inexpensively compared to the prior art.

[0012] According to the present invention, this object is achieved by a device for detecting high-frequency event signals in a rotating electrical machine, wherein at least two sensors for detecting low-frequency sensor signals are arranged in the rotating electrical machine, wherein each of the at least two sensors comprises an antenna for decoupling high-frequency event signals from the high-frequency electromagnetic field of the rotating electrical machine, wherein the sensors are connected to a common HF evaluation device via a common, in particular reactive, coupling element, and wherein the common coupling element is configured to transmit the high-frequency event signals from at least one of the sensors to the common HF evaluation device and to decouple the low-frequency sensor signals.

[0013] Furthermore, according to the present invention, this object is achieved by a method for detecting high-frequency event signals in a rotating electrical machine, wherein at least two sensors for detecting low-frequency sensor signals are arranged in the rotating electrical machine, wherein each of the at least two sensors comprises an antenna for decoupling high-frequency event signals from the high-frequency electromagnetic field of the rotating electrical machine, wherein the sensors are connected to a common HF evaluation device via a common, in particular reactive, coupling element, and wherein the high-frequency event signals are transmitted from at least one of the sensors to the common HF evaluation device via the common coupling element and decoupled from the low-frequency sensor signals.

[0014] Furthermore, according to the present invention, this object is achieved by a control unit having means for carrying out such a method.

[0015] Furthermore, according to the present invention, this object is achieved by a computer program for carrying out such a method when running in a control unit.

[0016] Furthermore, according to the present invention, this object is achieved by a computer program product having a computer program.

[0017] Furthermore, according to the present invention, this object is achieved by a rotating electrical machine having such a device with at least one for detecting high-frequency event signals.

[0018] The advantages and preferred design options for the device presented below can be meaningfully transferred to the method, control unit, computer program, computer program product, and rotating electrical machine.

[0019] The present invention is based on the consideration that during the operation of a rotating electrical machine, high-frequency event signals, such as partial discharges, are detected with minimal hardware expenditure. Components connected to the machine, such as cables, transformers, filters, etc., also belong to the rotating electrical machine, and such high-frequency event signals can be detected in these components. Since especially in high-frequency rotating electrical machines, high-frequency event signals can only be detected in a spatially limited manner, at least two sensors are used, which are connected to a common HF evaluation device via a common, especially reactive coupling element. The reactive coupling element is an especially passive electronic component, which is basically composed of energy storage components such as coils and capacitors. Therefore, the reactive components are very low-loss. In this way, multiple sensors can be evaluated via the HF evaluation device, which results in cost reduction due to reduced hardware expenditure. In addition, the circuit is smaller and simpler.

[0020] The sensors are designed, for example, as capacitive or inductive coupling devices, directional couplers, temperature probes, or other sensors. Since sensors for detecting low-frequency sensor signals already exist in the rotating electrical machine, no additional sensors are required, and no modification of the rotating electrical machine for detecting high-frequency event signals is required. The low-frequency sensor signals are, for example, signals with a frequency less than 1 kHz, while the high-frequency event signals are in the frequency range from 100 kHz to 100 MHz. The decoupling of the high-frequency event signals from the high-frequency electromagnetic field of the rotating electrical machine is effected by means of an antenna, where, for example, the feeder line of the sensor is used as the antenna, so that no additional modification is required. The common coupling element, for example, has a band-pass characteristic or a high-pass characteristic, such that in addition to transmitting the high-frequency event signals from at least one of the sensors to the common HF evaluation device, it is also configured to decouple the low-frequency sensor signals.

[0021] The method flow is controlled by a control unit. The means for performing the method include a computer program and, for example, a microcontroller or other programmable logic module. The control unit is, for example, assigned to the microcontroller.

[0022] In a preferred embodiment, the common, especially reactive coupling element has a transformer. In the frequency range of the low-frequency sensor signals, the transformer provides very good decoupling between the sensor and the HF evaluation device. In addition, the transformer has low losses in the frequency range of the high-frequency event signals and can be implemented inexpensively and compactly.

[0023] The transformer advantageously has a primary winding and a secondary winding, wherein for each of at least two sensors a primary winding is assigned respectively, wherein the secondary winding is assigned to the HF evaluation device, and wherein the primary windings are coupled to the secondary winding respectively. The windings have, for example, conductors made of copper in order to minimize losses, in particular ohmic losses.

[0024] If, for example, a partial discharge pulse is received by at least one of the sensors and transmitted to the corresponding primary winding, a pulse is induced in the secondary winding, which is received and further processed by the HF evaluation device. The remaining primary windings are loaded with a relatively high ohmic value, such that they only exert a negligible influence. With this wiring of the transformer, a very good decoupling between the sensors and the HF evaluation device is achieved in the frequency range of the low-frequency sensor signals. In addition, a low-loss transmission of the high-frequency event signals from each of the sensors can be realized inexpensively and compactly.

[0025] In another advantageous design, the transformer has a magnetic core, in particular a toroidal ferrite core. Such a magnetic core is made, for example, of a soft magnetic material having a high magnetic saturation flux density and a high magnetic permeability. Such soft magnetic materials are, for example, iron, some steels, nickel-iron alloys, cobalt-iron alloys or ferrites. The magnetic flux is bundled and guided with low losses through this magnetic core. In addition, the size of the transformer is reduced by increasing the inductance of the windings.

[0026] The primary and secondary windings are particularly advantageously arranged in a twisted manner with respect to each other in order to achieve as good a coupling as possible at higher frequencies, in particular at frequencies in the MHz range.

[0027] In a preferred embodiment, the sensors are respectively connected to an NF evaluation device for evaluating the low-frequency sensor signals, wherein the NF evaluation device is configured to decouple the high-frequency event signals. For example, the input impedance of the NF evaluation device is capacitive, such that the NF evaluation device appears as a high impedance for the low-frequency sensor signals, while it appears as a short circuit for the high-frequency event signals essentially. This wiring enables the simultaneous evaluation of the low-frequency sensor signals and the high-frequency event signals.

[0028] At least one of the sensors is particularly advantageously designed as a temperature probe. The temperature probe includes, for example, a temperature-dependent resistor made especially of platinum. For example, the feeder line of the temperature probe serves as an antenna for decoupling high-frequency event signals from the high-frequency electromagnetic field. Such temperature probes already exist in rotating electrical machines in particular. Since the low-frequency measurement of the temperature and the detection of the high-frequency event signals of the pulses do not significantly influence each other due to the different frequency ranges, such temperature probes are simple, inexpensive and space-saving as sensors.

[0029] In another advantageous design, the low-frequency sensor signal and the high-frequency event signal are differential signals. Such signals do not have a ground reference and are thus less susceptible to interference from the environment, especially electromagnetic interference.

[0030] In another advantageous embodiment, the sensors can be individually connected to a common, especially reactive, coupling element. The sensors can be connected to the coupling element individually, for example via switches, whereby the high-frequency event signals can be more precisely located, wherein the switches can be actuated especially via a control unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The invention will now be described and explained in detail based on the embodiments shown in the drawings.

[0032] The drawings show:

[0033] Figure 1 A longitudinal sectional view of a rotating electrical machine with a sensor device, and

[0034] Figure 2 A schematic illustration of a first design of a device for detecting high-frequency event signals in a rotating electrical machine, and

[0035] Figure 3 A schematic illustration of a second design of a device for detecting high-frequency event signals in a rotating electrical machine. DETAILED DESCRIPTION OF THE INVENTION

[0036] The embodiments explained below are preferred embodiments of the invention. In these embodiments, the components described for the embodiments are each individual, separately conceivable features of the invention, which features also improve the invention independently of one another and can thus be considered as components of the invention individually or in combinations different from the combinations shown. In addition, the described embodiments can also be supplemented by other features of the invention already described.

[0037] Identical reference numerals have the same meaning in different figures.

[0038] Figure 1 A longitudinal sectional view of a rotating electrical machine 2 with a device 4 for detecting high-frequency event signals is shown. The rotating electrical machine 2 is exemplarily embodied as a permanent magnet synchronous machine, wherein other machine types, such as asynchronous machines, also belong to the subject matter of the invention.

[0039] The rotating electrical machine 2 has a rotor 8 rotatable about a rotational axis 6 and a stator 10 surrounding the rotor 8, wherein a gap 12, in particular an air gap, is present between the rotor 8 and the stator 10. The rotational axis 6 defines an axial direction, a circumferential direction and a radial direction. The rotor 8 includes a shaft 14 and a rotor stack 16. The stator 10 includes a stator stack 18 having a stator winding 20, wherein the stator stack 18 is composed of a plurality of laminated electrical sheets. The stator winding 20 extends axially through the stator stack 18 and forms a winding head 22 at the axial end of the stator stack 18. The shaft 14 of the rotor 8 is supported via bearings 24. The rotor 8 and the stator 10 are arranged in a closed machine housing 26.

[0040] The device 4 for detecting high-frequency event signals includes a sensor 28 which is arranged, for example, in a channel 30 in the region of the stator winding 20. The channel 30 extends, for example, radially through the stator stack 18. Alternatively, the channel 30 is arranged in different directions, for example in the circumferential direction or the axial direction, so as to extend through the stator 10 or the rotor 8. For the sake of clarity, only the arrangement of the sensor device 4 is schematically shown, wherein in Figure 1 particular only one sensor 28 is shown. The sensor 28 is connected to an evaluation device 32 which is in turn connected to a central IT infrastructure 34. The central IT infrastructure 34 is, for example, at least one local computer system and / or a cloud. The central IT infrastructure 34 provides storage space, computing power and / or application software. In the cloud, storage space, computing power and / or application software are provided as services via the Internet. The digital data transmission to the central IT infrastructure 34 takes place wirelessly, wired or optically. For example, the data is transmitted via Bluetooth or a wireless local area network (WLAN).

[0041] Figure 2 A schematic illustration shows a first design of the device 4 for detecting high-frequency event signals in the rotating electrical machine 2, wherein, for the sake of clarity, the rotating electrical machine 2 and the arrangement of the sensor 28 in the rotating electrical machine 2 are shown highly abstractly. For example, three sensors 28 are used, wherein each of the three phases of the rotating electrical machine 2 is assigned a sensor. The high-frequency event signals can be understood, for example, as pulse signals in the frequency range from 100 kHz to 100 MHz. The pulses have a rectangular, Gaussian or other pulse shape. During operation of the rotating electrical machine 2, the high-frequency event signals are decoupled from the high-frequency electromagnetic field by means of the sensor 28. The high-frequency electromagnetic field is in particular generated by the rotating electrical machine 2.

[0042] The sensor 28 is exemplarily designed as a temperature probe, which respectively includes a temperature-dependent resistor made of, for example, platinum and a feeder line, wherein the feeder line serves as an antenna for decoupling high-frequency event signals. The sensor 28 is connected to a common HF evaluation device 38 via a common, especially reactive, coupling element 36, wherein the common coupling element 36 is configured to transmit the high-frequency event signal from at least one of the sensors 28 to the common HF evaluation device 38 and to decouple the low-frequency sensor signal. The coupling element 36 has a transformer, which has primary-side windings 40, 42, 44 and a secondary-side winding 46. The windings 40, 42, 44, 46 have conductors made of, for example, copper to minimize losses, especially ohmic losses. Optionally, the common, especially reactive, coupling element 36 includes additional components, such as components for power and / or impedance adaptation, such as coils and / or capacitors. The primary-side windings 40, 42, 44 are assigned to each of the sensors 28, and the secondary-side winding 46 is assigned to the HF evaluation device 38. The primary-side windings 40, 42, 44 are respectively coupled to the secondary-side winding 46 for transmitting the high-frequency event signal. A transformer with three primary-side windings 40, 42, 44 is exemplarily shown. Alternatively, depending on the number of sensors 28 to be connected, the transformer has two, four or more primary-side windings 40, 42, 44. The transformer has a magnetic core, especially a toroidal ferrite core, wherein the primary-side and secondary-side windings 40, 42, 44, 46 are twisted with each other and arranged wound around the ferrite core.

[0043] Additionally, the sensors 28 are respectively connected to a common NF evaluation device 48 to evaluate the low-frequency sensor signals, wherein each of the sensors 28 is connected to an input channel of the NF evaluation device 48. Alternatively, a dedicated NF evaluation device 48 is assigned to each of the sensors 28. The low-frequency sensor signal and the high-frequency event signal are especially differential signals. The primary-side windings 40, 42, 44 are respectively connected in series with the NF evaluation device 48, wherein the low-frequency sensor signal is decoupled via a transformer with a band-pass characteristic, and wherein the high-frequency event signal is decoupled via the input impedance Zin of the NF evaluation device. The input impedance Zin of the NF evaluation device 48 is especially capacitive, such that the NF evaluation device appears as a high impedance for the low-frequency sensor signal and appears as a short circuit for the high-frequency event signal. The line length between the NF evaluation device 48 and the coupling element 36 is especially electrically short, so that the short circuit after the line transformation does not significantly deteriorate the transmission of the HF signal between the sensor 28 and the coupling element 36.

[0044] If, for example, at least one of the sensors 28 receives a partial discharge pulse and transmits it to the windings 40, 42, 44 on the respective primary side, a pulse is induced in the winding 46 on the secondary side, which is received by the HF evaluation device 38 and further processed. The other windings 40, 42, 44 on the primary side are loaded with a relatively high resistance, in particular via temperature-dependent resistors, such that they exert only a negligible influence.

[0045] The common HF evaluation device 38 in particular has a high-frequency detector circuit 50 for detecting high-frequency event signals, an analog-to-digital converter 52 for digitizing the detected signals, and a control unit 54 for controlling the method flow. In addition, the HF evaluation device 38 is connected to the central IT infrastructure 34. Figure 2 Other embodiments of the device 4 in Figure 1 correspond to the embodiments in

[0046] Figure 2 A schematic illustration showing a second design of the device 4 for detecting high-frequency event signals in the rotating electrical machine 2. The sensors 28 can be individually connected to the windings 40, 42, 44 on the primary side of a common coupling element 36 implemented as a transformer via switches 56, 58, 60, whereby the high-frequency event signals can be more precisely located, wherein the switches can be actuated, for example, via the control unit 54. Figure 3 Other embodiments of the device 4 in Figure 2 correspond to the embodiments in

[0047] In summary, the invention relates to a device 4 for detecting high-frequency event signals in a rotating electrical machine 2, wherein at least two sensors 28 for detecting low-frequency sensor signals are arranged in the rotating electrical machine 2, and wherein the at least two sensors 28 each include an antenna for decoupling high-frequency event signals from the high-frequency electromagnetic field of the rotating electrical machine 2. In order to achieve a simple and inexpensive embodiment compared to the prior art, it is proposed that the sensors 28 are connected to a common HF evaluation device 38 via a common, in particular reactive, coupling element 36, wherein the common coupling element 36 is configured to transmit high-frequency event signals from at least one of the sensors 28 to the common HF evaluation device 38 and to decouple low-frequency sensor signals.

Claims

1. A device (4) for detecting event signals at high frequencies in a rotating electrical machine (2), wherein, At least two sensors (28) for detecting sensor signals of low frequency are arranged in the rotary electric machine (2). At least two of the sensors (28) each include an antenna for decoupling the event signal of high frequency from the high-frequency electromagnetic field of the rotary electric machine (2). It is characterized in that The sensors (28) are connected to a common HF evaluation device (38) via a common coupling element (36). The common coupling element (36) is configured to transmit the event signal of high frequency from at least one of the sensors (28) to the common HF evaluation device (38), and to decouple the sensor signal of low frequency, wherein the common coupling element (36) has a transformer, wherein the transformer has primary-side windings (40, 42, 44) and a secondary-side winding (46), wherein a primary-side winding (40, 42, 44) is assigned to each of at least two of the sensors (28), wherein the secondary-side winding (46) is assigned to the HF evaluation device (38), and wherein the primary-side windings (40, 42, 44) are each coupled to the secondary-side winding (46).

2. The device (4) according to claim 1, wherein, The coupling element is reactive.

3. The device (4) according to claim 2, wherein The transformer has a magnetic core.

4. The device according to claim 3, wherein, The magnetic core is a toroidal ferrite core.

5. The device (4) according to any one of claims 2 to 4, wherein, The primary-side windings and the secondary-side winding (40, 42, 44, 46) are arranged in a stranded manner with each other.

6. The device (4) according to any one of claims 1-4, Among them, The sensors (28) are each connected to an NF evaluation device (48) for evaluating the sensor signal of low frequency. The NF evaluation device (48) is configured to decouple the event signal of high frequency.

7. The device (4) according to any one of claims 1-4, wherein, At least one of the sensors (28) is configured as a temperature probe.

8. The device (4) according to any one of claims 1-4, wherein, The sensor signal of low frequency and the event signal of high frequency are differential signals.

9. The device (4) according to any one of claims 1 to 4, wherein The sensors (28) can be individually connected to the common coupling element (36).

10. A method for detecting an event signal of high frequency in a rotary electric machine (2). Among them, At least two sensors (28) for detecting sensor signals of low frequency are arranged in the rotary electric machine (2). At least two of the sensors (28) each include an antenna for decoupling the event signal of high frequency from the high-frequency electromagnetic field of the rotary electric machine (2). It is characterized in that The sensors (28) are connected to a common HF evaluation device (38) via a common coupling element (36). Wherein, the high-frequency event signal is transmitted from at least one of the sensors (28) to the common HF evaluation device (38) via the common coupling element (36), and the high-frequency event signal is decoupled from the low-frequency sensor signal, wherein the common coupling element (36) is implemented as a transformer, wherein the transformer has a primary-side winding (40, 42, 44) and a secondary-side winding (46), wherein a primary-side winding (40, 42, 44) is assigned to each of at least two of the sensors (28), wherein the secondary-side winding (46) is assigned to the HF evaluation device (38), and wherein the primary-side windings (40, 42, 44) are respectively coupled to the secondary-side winding (46).

11. The method according to claim 10, wherein, The coupling element (36) is reactive.

12. The method according to claim 11, wherein The primary-side winding and the secondary-side winding (40, 42, 44, 46) are twisted with each other.

13. The method according to any one of claims 10 to 12, Among them, The sensors (28) are respectively connected to a NF evaluation device (48) for evaluating the low-frequency sensor signal, wherein the NF evaluation device (48) is configured to decouple the high-frequency event signal.

14. The method according to any one of claims 10 to 12, wherein, The low-frequency sensor signal and the high-frequency event signal are transmitted differentially.

15. The method according to any one of claims 10 to 12, wherein The sensors (28) are respectively individually connected to the common coupling element (36).

16. A control unit (54) having means for performing the method according to any one of claims 10 to 15.

17. A computer program product having a computer program for performing the method according to any one of claims 10 to 15 when running in the control unit (54) according to claim 16.

18. A rotating electrical machine (2) having at least one device (4) according to any one of claims 1 to 9 for detecting high-frequency event signals.

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