DE102016222660A1 - Method and device for detecting changes in an electrically driven drive - Google Patents

Abstract

A method for detecting deviations and / or changes in at least one operating state of an electrically, in particular electromotive, driven drive (101), in particular for detecting a presence and / or occurrence and / or a development of damage to translationally moving components on such Drive, comprising the steps of: measuring at least one electric current supplied to the electrically driven drive for supplying electrical energy, performing a time-frequency analysis and / or an amplitude and / or RMS determination of the at least one measured electrical current, comparing one of Time frequency analysis obtained frequency spectrum of the at least one measured electrical current with a predetermined frequency spectrum and / or comparing an obtained from the amplitude and / or RMS value amplitude value and / or effective value of the at least one measured electrical chen current with a predetermined amplitude value or RMS value, triggering an error signal when a deviation of predeterminable size is determined when comparing won with predetermined frequency spectrum and / or amplitude value and / or effective value. The method and a device operating thereafter enable the drives to be monitored and timely detection of mechanical damage. The method according to the invention and the device according to the invention for detecting damage to translationally moving components of the drive (101) should be used.

Description

The invention relates to a method for detecting deviations and / or changes in at least one operating state of an electric, in particular electromotive, operated drive. The invention further relates to a device for carrying out this method.

Mechanical damage to drives, especially electrical drives, and consequent failures of these drives often lead to longer downtime of these drives and operated by these drives systems. An example is drives in manufacturing equipment, e.g. Plants in a press shop of the automotive industry. These systems include so-called transfer units with such drives, in particular electric drives. Failure of such a transfer unit due to mechanical damage to its drive easily results in longer downtime, i. Downtimes, of the entire system in which the transfer unit is integrated. Therefore, such mechanical damage causes considerable financial losses.

From the publication WO 2013/017515 A1 are a method for the safe monitoring of a three-phase motor fed by an intermediate circuit inverter and a device operating according to the method in which an inverter output power is determined from all phase currents and phase voltages and a DC link power from a DC link current and an intermediate circuit voltage determined powers are compared and an output signal is generated depending on the result of the comparison. If a deviation is found in a comparison of the two powers, an exceptional situation is detected, which is indicated by the output signal. As long as the two determined powers agree within the specified or predefinable limits, this is a redundant determination of at least one power value. This is intended to specify a method and a device for the reliable monitoring of a three-phase motor operated in particular in a field-oriented manner, in particular a method or a device which avoids the problem of a so-called simultaneity normalization error.

From the publication DE 10 2013 213 046 A1 a method for driving a polyphase inverter for operating an electric machine is known, wherein the inverter comprises half bridges each having a first power switch and a second power switch, wherein the first power switch is connected to a DC voltage and the second power switch is connected to a reference potential of the DC voltage and wherein the respective node of the first circuit breaker is connected to the second power switch with the respective phase strand of the electric machine. The method comprises the steps of: determining if there is an accident, if there is an accident: measuring whether a first current is flowing from the electric machine, and if there is a fault and the first current is flowing: converting the inverter into a short circuit mode. In a fault, in which, for example, a circuit breaker of the inverter has a defect, it should be ensured that the system in question is transferred to a state in which further damage is avoided. In particular, a return of electrical energy from the electric machine should be avoided, for which purpose the electric machine is converted into a short-circuit mode. However, in short-circuit mode, the whole system can be subjected to considerable stress by high currents. Therefore, the short-circuit mode should only be maintained as long as necessary. The method described should now easily enable an optimal change of state between the modes of short-circuiting and freewheeling in a fault.

From the post-published and attributable to the applicant itself document DE 10 2015 210 911 A1 Although a method for monitoring of electric motor-driven mechanical drives is already known, in which a current signal of the electric drive is used as a sensor for mechanical damage of the drive, but where the method is limited to the detection of damage to rotating components of the drive.

The invention has the object to provide a method and a device operating according to this method, which allows monitoring of drives, in particular electrical drives, for mechanical damage to translationally moving components and timely detection of such damage, so that the described failures and downtime are significantly reduced.

• - Messen wenigstens eines dem elektrisch betriebenen Antrieb zum Speisen mit elektrischer Energie zugeführten elektrischen Stroms,
• - Durchführen einer Zeit-Frequenz-Analyse und/oder einer Amplituden- und/oder Effektivwertbestimmung des wenigstens einen gemessenen elektrischen Stroms,
• - Vergleichen eines aus der Zeit-Frequenz-Analyse gewonnenen Frequenzspektrums des wenigstens einen gemessenen elektrischen Stroms mit einem vorgebbaren Frequenzspektrum und/oder
• - Vergleichen eines aus der Amplituden- und/oder Effektivwertbestimmung gewonnenen Amplitudenwertes und/oder Effektivwertes des wenigstens einen gemessenen elektrischen Stroms mit einem vorgebbaren Amplitudenwert bzw. Effektivwert,
• - Auslösen eines Fehlersignals, wenn beim Vergleichen von gewonnenem mit vorgebbarem Frequenzspektrum und/oder Amplitudenwert und/oder Effektivwert eine Abweichung vorgebbarer Größe festgestellt wird.

This object is achieved by a method for detecting deviations and / or changes in at least one operating state of an electrically, in particular electromotive, operated drive, in particular for detecting a presence and / or occurrence and / or a development of damage to translationally moving components Such a drive, comprising the steps:

• - Measuring at least one electrical current supplied to the electric drive for supplying electric energy,
• Performing a time-frequency analysis and / or an amplitude and / or RMS determination of the at least one measured electrical current,
• Comparing a frequency spectrum obtained from the time-frequency analysis of the at least one measured electrical current with a predefinable frequency spectrum and / or
• Comparing an amplitude value obtained from the determination of the amplitude and / or effective value and / or the effective value of the at least one measured electrical current with a predefinable amplitude value or effective value,
• - Triggering of an error signal when a deviation of predeterminable size is determined when comparing won with predetermined frequency spectrum and / or amplitude value and / or effective value.

An electrically operated drive is to be understood as any type of arrangement in which a mechanically movable device, i. mechanically movable elements, by electrical energy, supplied by at least one electric current, is movable or are. In particular, the invention relates to electric motor drives, i. electric motor operated arrangements with at least one element mechanically movable by the supply of electrical energy. Included therein are stationary and movable drives, e.g. for vehicles or manufacturing plants. Examples of such drives are machine tools and equipment and plant components used together, such as e.g. Transfer units in a press shop for the production of pressed parts from sheet metal, robot drives in an assembly plant, pump drives in a paint shop, elevators, chain conveyors, drives for electric vehicles, etc. Such a drive generally comprises any combination of shafts, bearings, gears, clutches, gears or the like , which are moved by electrical energy, in particular by an electric machine, preferably a three-phase motor, wherein both an asynchronous motor and a synchronous motor can be used.

In the context of the present invention, operating states are in particular characteristics of the drive that characterize its nature, these are primarily maintenance conditions and / or wear states and / or damage states, i. Damage, the drive, but not such operating parameters such as speed, power, torque, or the like.

A change of an operating state is a time-variable difference between an initial state and / or desired state on the one hand and a current actual state of this operating state on the other hand. Such a time-variable difference can arise quickly or suddenly. Such a rapid or abrupt emergence is referred to herein as occurrence. The term occurrence here is intended to designate an occurrence within minutes or less. Typical examples of an occurrence of a change in an operating state, in particular the occurrence of damage, are shaft breaks or tooth breaks in gears. A gradual emergence of a time-variable difference between an initial state and / or desired state on the one hand and a current actual state of this operating state on the other hand is referred to here as the development of a change in the operating state. Here, the term development here is to describe an emergence, which runs much slower than the occurrence, preferably over hours, days or larger periods of time. A typical example of a development of a change of an operating state, in particular also a damage, is a gradual change caused by increasing wear.

As a deviation of an operating condition, i. of its actual state, of the desired state, a time-constant difference between this nominal state and the actual state is designated here. Typically, such differences are already present at the beginning of carrying out the method according to the invention. This presence is referred to as presence. An example of a present deviation of an operating state is a manufacturing error already existing at the beginning of the implementation of the method according to the invention or an already present damage in the drive.

When measuring the at least one electric current, its time profile is advantageously detected, in particular its instantaneous values are sampled. This is done with a sufficiently high temporal resolution, which is dimensioned such that all frequency components of the predeterminable and hence the frequency spectrum of the current to be obtained are sufficiently accurately determined when carrying out the time-frequency analysis explained below, as well as the rms value and / or the amplitude value of the current can be.

In this time-frequency analysis, the frequency spectrum of the measured electric current, ie the spectrum of the frequency components occurring therein, is determined. By comparing the thus obtained frequency spectrum with the predeterminable frequency spectrum, which represents a desired state of the frequency spectrum, the obtained frequency spectrum is examined for an occurrence and / or a development and / or a presence of certain frequency components out. From the presence of these frequency components conclusions can be drawn on the operating condition of the drive. For example, the appearance or development of a new frequency component is an indication of a change in the drive. In this case, experiences gained during operation of the drive based on deviations occurring and / or changes in the at least one operating state can be evaluated such that specific, characteristic deviations and / or changes of the current occur with certain deviations and / or changes in the at least one operating state. With this assignment, error signals can be triggered directly by the method according to the invention, which in the manner of an automatic diagnosis contain information about the type and / or location of the deviations and / or changes of the at least one operating state, in particular direct information about type and / or or place of damage. From the emergence and / or presence of certain frequency components in the stream can thus be concluded directly on certain deviations or changes, ie errors or damage.

As such a time-frequency analysis, various methods known per se can be used. Examples of such time-frequency analysis methods are the so-called "wavelet analysis", "Spectrogram", "Instantaneous Frequency" and the so-called "Wigner function". Time-frequency analysis methods serve not only to determine a simple, in particular stationary, i. in the operation of time-constant frequency spectrum, but also consider a temporal change of this frequency spectrum during operation. With the time-frequency analysis method "Spectrogram", e.g. a spectrogram can be obtained as a result, which has similar characteristics as a frequency spectrum, but in addition a time axis by which the blurring problem of a frequency spectrum can be at least partially improved. In the "Instantaneous Frequency" time-frequency analysis method, the frequency is plotted over time, resulting in a result that is preferable to call a "frequency signal" rather than a "frequency spectrum". For this reason, in the context of the disclosure of the present invention with the concept of a frequency spectrum obtained in a time-frequency analysis is always a result of the type described above, i. e.g. a spectrogram or a frequency signal of the aforementioned kind, be circumscribed.

These time-frequency analysis methods have the advantage of at least partially being able to circumvent a blurring problem which occurs when using a Fourier transform when the drive is nonuniform, e.g. is operated with varying nominal value of the current and / or varying speed, which is also referred to as transient operation, because in this case the frequency components indicative of possible changes or damage can not be determined unambiguously. The time-frequency analysis is thus an analysis method adapted to the uncertainty problem, which is not limited to a uniform, i. stationary operation of the electric, in particular electromotive, operated drive, but especially in non-stationary operation the frequency components mentioned uniquely determined. The invention thus has the advantage, from a measurement of the at least one electric current, particularly preferably at least one phase current of a three-phase machine, with which the electrically, in particular electromotive, operated drive is advantageously designed, especially in a transient operation still all frequency components required for the comparison of the frequency spectrum to be obtained to determine with sufficient sharpness and thus to allow precise detection of the at least one operating state.

It is also possible to draw conclusions about the operating state of the drive from the comparison of the amplitude value obtained and / or the effective value of the current as the actual value with the predefinable amplitude value or effective value as desired value. In particular, an increased recovered RMS value is an indication of a change in an operating state of the drive.

In order to make the method insensitive to measuring inaccuracies and for the operation of the drive insignificant deviations and / or changes in the at least one operating state, it is advantageous to trigger the error signal only when comparing obtained with a predetermined frequency spectrum and / or amplitude value and / or RMS value a deviation of predeterminable size, ie at least of this size, is determined. In the case of the evaluation of the frequency spectrum, this deviation of predeterminable magnitude is a difference between spectral distributions of the acquired and predetermined frequency spectrum, ie a uniform or non-uniform spectral distribution of the differences of the individual frequency components of the frequency spectra, and in the case of the evaluation of Amplitude value and / or effective value by a difference between absolute values, optionally supplemented by a sign information. As a deviation of predeterminable size can also multistage threshold values are predetermined, so that a multistage error signal can be triggered and output, for example in the manner of a gradual error message, preferably in the manner in which it is based on a so-called traffic light visualization with in particular three stages, eg: "green" = "error-free", " yellow "=" a check is required "," red "=" faulty ". This will be further explained below.

The invention enables a simple and effective detection of deviations and / or changes in the at least one operating state of the electrically, in particular electromotive, operated drive. In particular, the invention enables a simple, comprehensive and effective detection of the presence and / or occurrence and / or development of damage, preferably mechanical damage, to components moving in a translatory manner. Particularly advantageous is the timely detection of damage or an imminent damage possible, i. Errors and damages can already be detected at a very early stage of development and thus be remedied. Thus, in addition to a reduction or avoidance of downtime of the respective drive and the costs caused thereby also a limitation of the damage height can be achieved, whereby further cost savings can be achieved. In this case, the drive is monitored as a system as a whole, not just individual elements of the drive in an advantageous manner. Nevertheless, only very simple measurements are required for this. Opposite e.g. an attempt to detect deviations and / or changes in the drive suggestive frequencies in the operation of the drive with vibration sensors, there is the advantage of being able to perform the inventive method using a simpler, more compact device that saves space and also a more precise evaluation of Measurements, in particular a better separation of error frequencies of individual components of the drive and thus an improved error detection and discrimination against the use of vibration sensors allows. It is possible in a simple manner, the evaluation and thus error detection directly on all the drive downstream mechanical systems, in particular by these operated units, devices or the like to extend, as far as their operating conditions affect the at least one of the drive current supplied. Further, the application of the time-frequency analysis allows recognition even in a dynamic, i.e. nonuniform, operation of the drive, so that monitoring of the drive can be done continuously and does not have to be limited to periods of uniform operation. This ensures an even better and reliable error detection, especially error early detection.

The advantages described above are particularly evident when a plurality of electrical drives are to be monitored at the same time or the installation space for accommodating sensors, in particular vibration sensors, in the drives is severely limited. For this, the invention provides a particularly simple, space-saving, low-cost, universal, flexible and effective solution.

Advantageous embodiments of the invention are characterized in the subclaims.

• - unabhängig vom gemessenen elektrischen Strom als feste Werte vorgegeben sind;
• - in wenigstens einer voraufgehenden Messung gewonnen werden;
• - aus einer Kombination fest vorgegebener Werte mit in wenigstens einer voraufgehenden Messung gewonnenen Werten bestimmt werden; insbesondere aus in wenigstens einer voraufgehenden Messung gewonnenen Werten bestimmt werden, solange diese Werte durch fest vorgegebene Werte bestimmte Grenzwerte nicht überschreiten, und ansonsten durch diese Grenzwerte bestimmt werden.

A preferred development of the method according to the invention is characterized in that the predefinable frequency spectrum and / or the predefinable amplitude value and / or the presettable effective value optionally

• - are given as fixed values regardless of the measured electric current;
• - be obtained in at least one previous measurement;
• - be determined from a combination of fixed values with values obtained in at least one previous measurement; in particular from values obtained in at least one previous measurement, as long as these values do not exceed certain limit values by means of predefined values and are otherwise determined by these limit values.

According to the first alternative of this preferred development, fixed reference values or limits are set for the detection of a deviation and / or change of an operating state. The second alternative enables execution of the method as a learning method. In particular, individual frequency spectrum, amplitude and / or rms value can be predetermined for a drive, with an initial operating state of the drive being defined as a desired state, irrespective of its nature. Advantageously, this determination may be on the basis of averaging over a number of initial measurements. However, this only changes compared to the initial operating state are detected, but not previously existing deviations from a desired operating state. The third alternative, as a combination of both of the above alternatives, is particularly intended for a case of operation in which minor changes over an operating period, i. in particular from measurement to measurement, be tolerated as natural wear in the context of the intended use of the drive: If, however, absolutely fixed limit values are exceeded, the error signal is triggered even if the excess is arbitrarily slow in time.

• - wird das aus der Zeit-Frequenz-Analyse gewonnene Frequenzspektrum des wenigstens einen gemessenen elektrischen Stroms im Vergleich mit dem vorgebbaren Frequenzspektrum auf ein Vorhandensein wenigstens eines Teil-Frequenzspektrums des gewonnenen Frequenzspektrums geprüft,
• - wobei das wenigstens eine Teil-Frequenzspektrum von einer bestimmten Art und/oder einem bestimmten Ort einer bestimmten frequenzabhängigen Abweichung und/oder Veränderung in wenigstens einem der Betriebszustände, insbesondere einem bestimmten Schaden, des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs herrührt, insbesondere von einem Lagerschaden, einem Zahnschaden eines Zahnrades oder einer Zahnstange des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs,
• - wird aus dem Vorhandensein des wenigstens einen Teil-Frequenzspektrums ein Vorliegen und/oder ein Auftreten und/oder eine Entwicklung der bestimmten Art und/oder des bestimmten Ortes der bestimmten frequenzabhängigen Abweichung und/oder Veränderung in dem wenigstens einen der Betriebszustände, insbesondere des bestimmten Schadens, des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs erkannt und
• - wird ein die bestimmte Art und/oder den bestimmten Ort der bestimmten frequenzabhängigen Abweichung und/oder Veränderung in dem wenigstens einen der Betriebszustände, insbesondere den bestimmten Schaden, des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs kennzeichnendes Fehlersignal ausgelöst.

In a further preferred embodiment of the method according to the invention

• the frequency spectrum of the at least one measured electrical current obtained from the time-frequency analysis is checked for the presence of at least one partial frequency spectrum of the acquired frequency spectrum in comparison with the predefinable frequency spectrum,
• - Wherein the at least one sub-frequency spectrum of a certain type and / or a specific location of a specific frequency-dependent deviation and / or change in at least one of the operating states, in particular a certain damage of the electrically, in particular electromotive, driven drive originates, in particular of one Bearing damage, a tooth damage of a toothed wheel or a toothed rack of the electrically, in particular electromotive, operated drive,
• the presence and / or occurrence and / or development of the particular type and / or location of the determined frequency-dependent deviation and / or change in the at least one of the operating conditions, in particular of the determined one, is determined by the presence of the at least one sub-frequency spectrum Damage, the electric, in particular electric motor, powered drive detected and
• a signal indicating the specific nature and / or location of the particular frequency-dependent deviation and / or change in the at least one of the operating conditions, in particular the specific damage, of the electric, in particular electromotive, driven drive is triggered.

This embodiment of the method according to the invention makes use of the knowledge that certain deviations and / or changes in the operating states, in particular certain damages, of the drive have a specific, characteristic frequency dependence. This is reflected in a different training of the obtained frequency spectra for different causes of deviations and / or changes in the operating conditions, in particular for different causes of error or damage, i. for different types of deviations and / or changes and / or for different locations where the deviations and / or changes occur, taking into account that certain deviations and / or changes, in particular errors and / or damages, only on certain components of the Drive, ie certain locations within the drive, can occur. Preferred examples of frequency-dependent deviations and / or changes, especially faults and / or damages, are tooth damage, e.g. gearbox damage or damage to racks. Tooth damage e.g. Although different harmonic frequency components are shown on different gear wheels and bearing damage, they can be distinguished from one another by their frequency values.

• - wird der aus der Amplituden- und/oder Effektivwertbestimmung gewonnene Amplitudenwert und/oder Effektivwert des wenigstens einen gemessenen elektrischen Stroms im Vergleich mit dem vorgebbaren Amplitudenwert bzw. Effektivwert auf eine Abweichung und/oder Veränderung, insbesondere Erhöhung, des gewonnenen Amplitudenwertes und/oder Effektivwertes gegenüber dem vorgebbaren Amplitudenwert bzw. Effektivwert geprüft,
• - wobei die Abweichung und/oder Veränderung, insbesondere Erhöhung, des gewonnenen Amplitudenwertes und/oder Effektivwertes gegenüber dem vorgebbaren Amplitudenwert bzw. Effektivwert von einer bestimmten, vom Amplitudenwert und/oder Effektivwert abhängigen Abweichung und/oder Veränderung in wenigstens einem der Betriebszustände des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs herrührt, insbesondere von einer durch Verschleiß des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs hervorgerufenen Abweichung und/oder Veränderung in wenigstens einem der Betriebszustände des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs,
• - wird aus der Abweichung und/oder Veränderung, insbesondere Erhöhung, des gewonnenen Amplitudenwertes und/oder Effektivwertes vom vorgebbaren Amplitudenwert bzw. Effektivwert ein Vorliegen und/oder ein Auftreten und/oder eine Entwicklung der bestimmten, vom Amplitudenwert und/oder Effektivwert abhängigen Abweichung und/oder Veränderung des wenigstens einen der Betriebszustände des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs, insbesondere ein Vorliegen und/oder ein Auftreten und/oder eine Entwicklung der durch Verschleiß des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs hervorgerufenen Abweichung und/oder Veränderung in dem wenigstens einen der Betriebszustände des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs, erkannt und
• - wird ein die bestimmte, vom Amplitudenwert und/oder Effektivwert abhängige Abweichung und/oder Veränderung des wenigstens einen der Betriebszustände des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs, insbesondere die durch Verschleiß des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs hervorgerufene Abweichung und/oder Veränderung in dem wenigstens einen der Betriebszustände des elektrisch, insbesondere elektromotorisch, betriebenen Antriebs, kennzeichnendes Fehlersignal ausgelöst.

According to a further preferred embodiment of the method according to the invention

• the amplitude value and / or effective value of the at least one measured electrical current obtained from the determination of the amplitude and / or rms value is compared to the predefinable amplitude value or effective value to a deviation and / or change, in particular increase, of the obtained amplitude value and / or effective value tested against the predefinable amplitude value or effective value,
• wherein the deviation and / or change, in particular increase, of the obtained amplitude value and / or effective value relative to the predefinable amplitude value or effective value is dependent on a specific deviation dependent on the amplitude value and / or effective value and / or change in at least one of the operating states of the electric, in particular electric motor driven drive, especially from a caused by wear of the electric, in particular electromotive, driven drive deviation and / or change in at least one of the operating states of the electrically, in particular electric motor driven drive,
• the deviation and / or change, in particular increase, of the obtained amplitude value and / or effective value from the predefinable amplitude value or effective value results in the presence and / or occurrence and / or development of the determined deviation dependent on the amplitude value and / or effective value / or change in the at least one of the operating states of the electrically, in particular electromotive, operated drive, in particular a presence and / or occurrence and / or development of the caused by wear of the electric, in particular electric motor driven drive deviation and / or change in the at least one of the operating states of the electrically, in particular electric motor, operated drive, recognized and
• - is a deviation, which depends on the amplitude value and / or effective value, and / or change of the at least one of the operating states of the electrically, in particular electromotively, operated drive, in particular the deviation and / or change caused by wear of the electrically, in particular electromotively, driven drive the at least one of the operating states of the electrically, in particular electromotive, operated drive, characteristic error signal triggered.

This embodiment is based on the finding that a drive of the type described with increasing wear in particular of its moving components shows a change in its electrical power consumption and thus the amplitude value or effective value of the at least one supplied electric current. In particular, as the wear progresses, a frequency-independent increase in the electrical power consumption and thus in the amplitude value or effective value of the at least one supplied electrical current is recorded. A deviation and / or change in the electrical current can therefore advantageously be evaluated as an indication of present or progressive wear. In particular, in a drive of the type described above, wear on components such as e.g. Sliding slides, gears, racks, bearings, clutches or so-called Rotexsternen or the like, or wear damage to pumps such as in particular wear of piston liners, in particular on axial piston pumps, are recognized.

For a precise evaluation, i. an exact detection of the wear-related deviation and / or change of the at least one electrical current, may preferably be provided to filter deviations and / or changes in the electrical current, which are due to other causes, from the at least one measured current. This is advantageously feasible, in particular, for frequency-dependent deviations and / or changes in the electrical current which make it possible to conclude frequency-dependent errors or damage. If all frequency-dependent components of the deviation and / or change in the electrical current are filtered out, the frequency-independent deviation and / or change in the amplitude value or effective value of the electric current, which is used as a measure, in particular for the wear, is obtained as the remaining deviation and / or change in the electrical current is used.

According to a further preferred embodiment of the method according to the invention, the deviation and / or change, in particular increase, of the obtained amplitude value and / or effective value of the at least one measured electrical current compared to the predeterminable amplitude value or effective value of the at least one measured electrical current are on the one hand intended use of the electric, in particular electromotive, driven drive with different set values for amplitude value and / or RMS induced variations of the amplitude value and / or RMS of the at least one measured electrical current on the other hand further control data of electrically, in particular electromotive, operated drive used, in particular further the setpoints descriptive control data from a programmable logic controller of the electrically, in particular electromotive, operated An drive. With this embodiment, it is possible to differentiate control-related deviations and / or changes, in particular increases, of the obtained amplitude value and / or effective value of the at least one measured electrical current from wear-related deviations and / or changes, in particular increases. In order to measure the current, it is then no longer necessary to control the drive in such a way that, e.g. Without wear for the at least one measured electrical current of the predetermined amplitude value or RMS value would set. Instead, the measurement and thus the monitoring of the drive at any time, so also continuously during operation, take place. The predefinable amplitude value or rms value is dependent on the modulation, i. depending on the use of the drive during operation different, also time-variable, i. dynamic, predetermined and compared with the control-dependent measured amplitude value or effective value, so that a control-independent deviation and / or change is obtained.

In a further preferred embodiment of the method according to the invention by the error signal is a message of a detected error, in particular a visualization of the detected error, and / or an intervention in an operation of electrically, in particular electric motor operated drive, in particular an at least partial shutdown of the electric, in particular electric motor, operated drive, triggered and / or controlled. This on the one hand, a simple and rapid detection or perception of an error by an operator and / or monitoring person of the drive and on the other hand, a limitation and / or avoidance of damage, especially extensive damage to the drive and / or resulting consequential damage achieved. The visualization can be easy as Set traffic light visualization or incorporated into more extensive monitoring systems, for example, in a computer-controlled monitoring system for a system with a variety of drives of the type described. The shutdown takes place in the simplest case by completely switching off the detected as faulty drive, however, depending on the detected type of error be provided different forms of decommissioning. For example, upon detection of exceeding a wear limit of the affected drive in a transitional time interval with output of an error message continues to be operated to avoid major deterioration of the performance of surrounding or interacting with the affected drive system parts, but be switched off suddenly, as soon as a destruction of a component of the Drive is detected.

• - Messmittel zum Messen wenigstens eines wenigstens einem der elektrisch betriebenen Antriebe zum Speisen mit elektrischer Energie zugeführten elektrischen Stroms, insbesondere Messmittel zum wenigstens nahezu zeitkontinuierlichen Messen wenigstens eines Augenblickswertes des wenigstens einen elektrischen Stroms,
• - erste Signalverarbeitungsmittel zum Durchführen einer Zeit-Frequenz-Analyse des wenigstens einen gemessenen elektrischen Stroms und/oder
• - zweite Signalverarbeitungsmittel zum Durchführen einer Amplituden- und/oder Effektivwertbestimmung des wenigstens einen gemessenen elektrischen Stroms,
• - erste Vergleichsmittel zum Vergleichen eines in den ersten Signalverarbeitungsmitteln aus der Zeit-Frequenz-Analyse gewonnenen Frequenzspektrums des wenigstens einen gemessenen elektrischen Stroms mit einem vorgebbaren Frequenzspektrum und/oder
• - zweite Vergleichsmittel zum Vergleichen eines in den zweiten Signalverarbeitungsmitteln aus der Amplituden- und/oder Effektivwertbestimmung gewonnenen Amplitudenwertes und/oder Effektivwertes des wenigstens einen gemessenen elektrischen Stroms mit einem vorgebbaren Amplitudenwert bzw. Effektivwert, sowie
• - Signalerzeugungsmittel zum Auslösen eines Fehlersignals, wenn beim Vergleichen von gewonnenem mit vorgebbarem Frequenzspektrum und/oder Amplitudenwert und/oder Effektivwert eine Abweichung vorgebbarer Größe festgestellt wird.

The above object is further achieved by a device for detecting deviations and / or changes in operating states electrically, in particular electromotive, powered drives, in particular for detecting a presence and / or occurrence and / or development of damage, preferably mechanical damage, at such drives, at least comprising:

• Measuring means for measuring at least one electrical current supplied to at least one of the electrically operated drives for feeding with electrical energy, in particular measuring means for measuring at least one instantaneous value of the at least one electrical current at least almost continuously
• - First signal processing means for performing a time-frequency analysis of the at least one measured electric current and / or
• second signal processing means for performing an amplitude and / or rms value determination of the at least one measured electrical current,
• first comparison means for comparing a frequency spectrum, obtained in the first signal processing means from the time-frequency analysis, of the at least one measured electrical current with a predefinable frequency spectrum and / or
• second comparison means for comparing an amplitude value obtained in the second signal processing means from the amplitude and / or effective value determination and / or effective value of the at least one measured electrical current with a predefinable amplitude value or effective value, and
• - Signal generating means for triggering an error signal when a deviation of predeterminable size is determined when comparing obtained with predetermined frequency spectrum and / or amplitude value and / or RMS value.

The measuring means are preferably designed as a current measuring circuit and / or with at least one current transformer. However, the measuring means may also be included in facilities for powering the drives. For example, in drives that are designed with three-phase machines, phase currents or phase current signals of three-phase machines can either be measured with current transformers or read directly from upstream frequency converters, the frequency converter in the latter case include the measuring means. The measuring means can be set up to measure the electrical current to be measured continuously or to disperse time-discretely, in which latter case a sampling frequency is to be selected which makes it possible to detect all those frequency components of the measured electrical current, the deviations to be detected, changes, Errors or damage are needed.

Preferably, the device according to the invention is further configured with first storage means for storing the predeterminable frequency spectrum and / or with second storage means for storing the predefinable amplitude value or effective value. The memory means may be designed to store said specifiable data in the manner of read-only memories, also referred to as ROM, or as read-write memories. In the latter case, the predefinable frequency spectrum and / or the predeterminable amplitude value or effective value can be made adaptable or can be determined from initial measurements and accordingly be individually storable. An operating condition found at the beginning of the operation of the relevant drive is then defined as the desired condition. The device can then be designed as a learning device.

More preferably, the device according to the invention is formed with reporting means that can be designed in particular with visualization means and / or means for dispensing at least one acoustic warning signal. The reporting means are used to transmit a message and / or information about a detected deviation and / or change in at least one operating state, in particular an operator and / or monitoring person. Preferably, the message with a warning sound and / or a warning light, a traffic light visualization with at least the display levels "error-free", "verification required" or "repair is soon due "and" error "or" damage "be configured. The reporting means can be assigned separately from other systems only a selected one of the electric drives and be arranged directly on this or in its immediate, spatial proximity. The reporting means may also be part of a larger device, such as a surveillance network, which is designed to monitor a larger plant, such as a manufacturing plant with a plurality of such drives or a vehicle with a variety of different devices and / or devices to be monitored. Thus, the reporting means may be configured to display a status and / or error indication within a more extensive monitoring display.

Advantageously, the device according to the invention is optionally further formed with control means for engaging in an operation of the drive, in particular for decommissioning of the drive, after detected deviation and / or change in at least one operating state. Preferably, a different intervention is provided depending on the nature of the error that has occurred. Thus, the affected drive can optionally be operated at a lower speed, i. In particular speed, continue to operate in order to avoid a sudden stop and thus possibly greater impact on a system in which the drive is involved. This can e.g. be advantageous in an error message on exceeding a wear limit, if the exceeding of the wear limit still no immediate damage occurs, but with such a continuation of the use of the drive, for. under full load is to be expected. Optionally, such a "soft" intervention already with an error message "inspection required" or "repair will be due soon" or coupled with an error message "error" or "damage". In the case of such deviations and / or changes in operating states, it may be sufficient to drive the affected drive in anyway, e.g. to maintain, overhaul, replace or repair at regular service intervals, scheduled downtimes of the drive or the entire system. If, however, a particular abrupt change in an operating condition is detected, an equally abrupt shutdown in the sense of a "hard" intervention in the operation may be useful or necessary and carried out to consequential damage, a loss due to downtime of the drive or a larger system in the drive is used to exceed, exclude or keep as low as possible.

Both the signaling means and the control means are prematurely controllable by the signal generating means for triggering the error signal.

Optionally, recording means are further preferably provided for recording a detected deviation and / or triggering of the error signal and / or the message and / or information about the detected deviation and / or the intervention in the operation of the drive in the manner as Tachograph or black box is known per se. Logging is not solely for administrative purposes; Rather, data on, in particular, a development of different changes and / or errors in the at least one monitored drive can thus also be collected, which can subsequently be used for a more exact condition monitoring and / or error detection. These data can, after appropriate evaluation, be supplied to the storage means for storing the predefinable frequency spectrum and / or the predefinable amplitude value or effective value in the sense of the mentioned learning device.

• - wenigstens einem Sensor, insbesondere Stromsensor, der die Messmittel zum Messen des wenigstens einen wenigstens einem der elektrisch betriebenen Antriebe zum Speisen mit elektrischer Energie zugeführten elektrischen Stroms bildet, z.B. Stromwandler zur Phasenstrommessung an Drehstrommotoren oder Sensoren zur Strommessung an vorgeschalteten Frequenzumrichtern und/oder deren Regelungseinrichtungen;
• - einer, bevorzugt digitalen, Signalverarbeitungseinrichtung, bevorzugt einem Rechner, besonders bevorzugt einem Überwachungsrechner, einem Anlagensteuerungsrechner oder einem Fahrzeug-Bordrechner, umfassend die vorgenannten ersten und/oder zweiten Signalverarbeitungsmittel und die vorgenannten ersten und/oder zweiten Vergleichsmittel, sowie
• - einer Signalisierungseinheit, insbesondere Visualisierungseinheit, bevorzugt einer Bildschirmanzeige, besonders bevorzugt eingebunden in weitere Anzeigen über den Betrieb des Antriebs und/oder des Ihn umfassenden Fahrzeugs bzw. der ihn umfassenden Anlage.

The device according to the invention is thus formed in a simple manner, in particular with the following components:

• - At least one sensor, in particular current sensor, which forms the measuring means for measuring the at least one of the electrically operated drives for feeding electrical energy supplied electrical current, eg current transformer for phase current measurement of three-phase motors or sensors for current measurement of upstream frequency inverters and / or their control devices ;
• - One, preferably digital, signal processing device, preferably a computer, particularly preferably a monitoring computer, a plant control computer or a vehicle on-board computer, comprising the aforementioned first and / or second signal processing means and the aforementioned first and / or second comparison means, as well
• a signaling unit, in particular a visualization unit, preferably a screen display, particularly preferably integrated into further displays about the operation of the drive and / or the vehicle comprising it or the installation comprising it.

The signal processing device forms an evaluation unit, which is preferably operated with an evaluation algorithm with which the method steps described above are carried out. The evaluation algorithm can be designed in such a way that, even before the operation of a described drive is started, initial values for its operating states, in particular for a predefinable frequency spectrum and / or for a predefinable amplitude value or effective value, are obtained the at least one electrical current to be measured, from known design data of the drive - eg bearing frequencies, tooth frequencies in gears and the like - determined and checked during initial commissioning and / or adjusted. The frequencies mentioned, for example, occur in frequency sidebands of the current to be measured by an amplitude modulation. This makes it easy to separate in a case of damage the attributable to the damage frequencies for the evaluation. For drives that contain gears and / or racks, eg gearboxes, the frequencies attributable to the damage can be determined for the evaluation by means of a tooth engagement, eg in the gearbox. In an operation such as a transmission with different speeds then occur on different frequencies. Here, it is preferable to determine in advance the frequencies which are characteristic of the rotational speeds used and which are to be used for monitoring the operating states.

In order to obtain the predefinable frequency spectrum and / or the predefinable amplitude value or rms value of the at least one electrical current to be measured and for certain errors and / or damage of characteristic deviations and / or changes in the measured current, it is further advantageous, e.g. carry out measurements in preliminary investigations and to determine the errors and / or damages which have occurred or are present at the same time, preferably by means of visual inspection, mechanical examination and / or surveying. In this way, additional information about errors and / or damage can then be included in the error signal to be triggered.

The above-mentioned object is also achieved by a computer program product comprising program parts for carrying out a method of the aforementioned type, by a machine-readable, in particular computer-readable, data structure generated by such a method and / or by at least one such computer program product and by a machine-readable, in particular computer-readable , Data carrier on which at least one such computer program product is recorded and / or stored and / or on which at least one such data structure is kept ready for retrieval.

• 1 ein grob schematisches Blockschaltbild eines Beispiels für eine erfindungsgemäße Vorrichtung,
• 2 ein Ritzel als Beispiel eines Bauteils eines Antriebs, der mit einer erfindungsgemäßen Vorrichtung, bevorzugt gemäß 1, ausgebildet ist, im gesunden Betriebszustand,
• 3 ein Beispiel eines Frequenzspektrums, wie es an einem Antrieb gemäß 1 mit einem gesunden Ritzel gemäß 2 für einen dem Antrieb zugeführten elektrischen Strom gemessen wird,
• 4 das Ritzel gemäß 2 in einem beschädigten Betriebszustand, auch als Schadenszustand bezeichnet,
• 5 ein Beispiel eines Frequenzspektrums, wie es an einem Antrieb gemäß 1 mit einem beschädigten Ritzel gemäß 4 für einen dem Antrieb zugeführten elektrischen Strom gemessen wird,
• 6 ein grob schematisches Blockschaltbild einer detaillierteren Darstellung eines Teils der Anordnung gemäß 1,
• 7 ein Diagramm mit der Darstellung von Drehzahl und Phasenstrom im Zeitbereich,
• 8 eine Zeit-Frequenzanalyse des Phasenstroms,
• 9 eine Darstellung des Phasenstroms und der Drehzahl im Wegbereich,
• 10 eine Zeit-Frequenzanalyse im Wegbereich,
• 11 eine Darstellung der Kombination der Zeit-Frequenzanalyse und der Auswertung der Regeldifferenz der Drehzahl und
• 12 eine vereinfachte Darstellung eines Programmablaufplanes der einzelnen Prozess-Schritte.

Embodiments of the invention are illustrated in the drawings and will be described in more detail below, with matching elements in all figures are given the same reference numerals and a repeated description of these elements is omitted. Show it:

• 1 a rough schematic block diagram of an example of a device according to the invention,
• 2 a pinion as an example of a component of a drive, with a device according to the invention, preferably according to 1 , is formed, in healthy operating condition,
• 3 an example of a frequency spectrum, as in a drive according to 1 with a healthy pinion according to 2 for an electric current supplied to the drive,
• 4 the pinion according to 2 in a damaged operating condition, also called damage condition,
• 5 an example of a frequency spectrum, as in a drive according to 1 with a damaged pinion according to 4 for an electric current supplied to the drive,
• 6 a rough schematic block diagram of a more detailed representation of a portion of the arrangement according to 1 .
• 7 a diagram showing the speed and phase current in the time domain,
• 8th a time-frequency analysis of the phase current,
• 9 a representation of the phase current and the speed in the path area,
• 10 a time-frequency analysis in the path area,
• 11 a representation of the combination of the time-frequency analysis and the evaluation of the control difference of the speed and
• 12 a simplified representation of a program flow chart of the individual process steps.

In 1 is with the reference numeral 100 An exemplary embodiment of a device according to the invention, which is for detecting deviations and / or changes in operating states of an electric motor driven drive 101 is set up. In particular, the device 100 for detecting a presence and / or occurrence and / or development of damage, preferably mechanical damage, to the drive 101 educated. The drive 101 in the present example comprises a three-phase machine 102 that have live connections U . V . W is fed with three phase currents causing phase voltages. The three-phase machine 102 downstream, ie operated by the three-phase machine, here is for example a mechanical system 103 that at least one camp 104 , a clutch 105 , a gearbox 106 and / or at least one gear 107 and a rack 108 includes. Also the three-phase machine 102 preferably includes bearings that act as mechanical components of the drive 101 in the same way as the enumerated components of the mechanical system 103 a monitoring to detect the deviations and / or changes in the operating states of the drive 101 through the device 100 should be subject.

To perform this monitoring, the device includes 100 measuring Equipment 109 for measuring the three-phase machine 102 of the drive 101 for feeding with electrical energy supplied electrical currents, designed here as a current transformer for measuring phase currents of the three-phase machine 102 , In particular, these measuring means 109 designed for at least almost continuous measurement of the instantaneous values of the phase currents. The measuring equipment 109 are with a signal processing device 110 connected for supplying measured values of the measured electrical currents, ie the measured phase currents. The signal processing device 110 forms an evaluation unit for evaluating the measured values of the phase currents and for performing the monitoring and detection of the deviations and / or changes in the operating states of the drive 101 , The operating conditions are monitored, ie in particular mechanical conditions of maintenance or damage and / or wear of the three-phase machine 102 , in particular their bearings, as well as the mechanical system 103 with the at least one camp 104 , the clutch 105 , the transmission 106 and / or the at least one gear 107 as well as the rack 108 , This monitoring is by arrows 111 symbolizes.

In 6 is a part of the device according to a rough schematic block diagram 1 reproduced in more detail. This includes the signal processing device 110 one with the measuring equipment 109 , here the current transformers, coupled measuring stage 112 for picking up and forwarding from the current transformers 109 Recorded measured values of the phase currents of the three-phase machine 102 , The signal processing device 110 comprises first signal processing means 113 for performing a time-frequency analysis of the phase currents and second signal processing means 114 for performing an amplitude and / or RMS determination of the phase currents. The first and second signal processing means 113 . 114 the measured values of the phase currents are transmitted via signal connections 115 from the measuring stage 112 fed. In the first signal processing means 113 is obtained by means of the time-frequency analysis of the phase currents, a frequency spectrum of these phase currents and related data via a signal connection 116 first comparison means 117 fed. In the second signal processing means 114 amplitude values and / or rms values of these phase currents are obtained from the phase currents by means of the determination of the amplitude and / or rms value, and data relating thereto are transmitted via a signal connection 118 second comparison means 119 fed.

The first comparison means 117 are formed for comparing the obtained frequency spectrum of the measured phase currents with a predetermined frequency spectrum. The second comparison means 119 are formed for comparing the obtained amplitude values and / or RMS values of the measured phase currents with predefinable amplitude values or RMS values. For this purpose, the signal processing device comprises 110 furthermore first storage means 120 for storing the predefinable frequency spectrum and second memory means 121 for storing the predefinable amplitude values or effective values. The predetermined frequency spectrum data are the first comparison means 117 via a signal connection 122 fed. The specifiable amplitude values or RMS values are the second comparison means 119 via a signal connection 123 fed.

The signal processing device 110 downstream are signal generating means 124 for triggering an error signal if a deviation of predeterminable magnitude is determined when comparing acquired with specifiable frequency spectrum and / or amplitude value and / or effective value. These are the signal generating means 124 , here designed as a signal generation stage, via signal connections 125 respectively. 126 Results of these comparisons supplied data. In the signal generation stage 124 the error signal is generated and provided for further use.

The error signal is in the device 100 according to 6 register means 127 supplied, also referred to as a signaling unit. This reporting agent 127 comprise on the one hand visualization means 128 , Here is a visualization unit or display, which is designed for example as a warning lamp, screen or the like and the error signal via a signal connection 129 supplied receives. Furthermore, the reporting means include 127 medium 130 for outputting an audible warning signal to which the error signal from the signal generation stage 124 via a signal connection 131 is supplied. The reporting means 127 thus serve to transmit a message or information about detected deviations and / or changes in the monitored drive 101 by a warning tone and / or a warning lamp, a traffic light display, an indicator via a surveillance network, or the like.

From the signal generation stage 124 the error signal is sent to the other via a signal connection 133 control means 132 for intervention in operating the drive 101 , in particular for decommissioning the drive 101 by switching off the three-phase machine 102 , after detected deviation or change of operating state of the drive 101 , in particular for decommissioning after detection of damage. Advantageously, in a modification, a different intervention may be provided, depending on the type of deviation or change or the error, eg driving the drive 101 at reduced speed or speed or immediate, abrupt shutdown. Also, this different intervention is about a related information in the error signal by the signal generating means 124 controllable.

Furthermore, the device comprises 100 recording means 134 for logging the detected deviation and / or the triggering of the error signal and / or the message or information about the detected deviation and / or the intervention in the operation of the drive 101 , Corresponding data becomes the recording means 134 from the first and second signal processing means 113 . 114 and the signal generating means 124 via signal connections 135 fed. With the logging is an improved detection of a relationship of certain deviations and / or changes of the measured phase currents to detected errors and / or damage to the drive 101 possible and thus a more precise, reliable evaluation of the measured values obtained.

Through the measured phase currents at the three-phase machine 102 Even in non-stationary operation and without prior knowledge of a definable frequency spectrum and / or predefinable amplitude values and / or RMS values of the phase currents in a "healthy", ie error-free, operating state of the drive information about a current operating condition and its classification as "healthy" or "bad" win. In this case, it is possible to proceed as follows.

From a first measurement of the phase currents, a frequency spectrum, an amplitude value and / or an effective value are determined. An operating state described therewith, ie the operating state present in this first measurement, is then defined as a "desired operating state"; the frequency spectrum obtained or the amplitude value and / or effective value obtained are used as a predefinable frequency spectrum or predefinable amplitude value and / or effective value in the first or second memory means 120 . 121 stored in the other and as a predetermined frequency spectrum or predetermined amplitude value and / or RMS the first or second comparison means 117 respectively. 119 over the signal connections 122 respectively. 123 made available. The transmission of the acquired frequency spectrum or of the obtained amplitude value and / or effective value from the first or second signal processing means 113 respectively. 114 as specifiable frequency spectrum or predefinable amplitude value and / or effective value to the first or second storage means 120 . 121 done via in 6 symbolically represented signal connections 136 respectively. 137 ,

The so-called "target operating state" is at the same time as a "healthy" state of the drive 101 defined without first the actual operating state, ie the actual nature of the drive 101 is known. However, if it turns out in further operation that the so-defined "target operating state" is actually a "damage state", that is, when determining the "target operating state" already a damage and / or error in the drive 101 If this error and / or damage has been rectified, the "target operating status" must be defined again.

In operation of the drive 101 Then further measurements of the phase currents are made, from which a frequency spectrum or an amplitude value and / or RMS value are obtained, which now rewrite an operating state, which is now defined as an "actual operating state". These measurements are preferred for determining the "desired operating state" and the "actual operating state" under as identical as possible operating conditions for the drive 101 performed. The predefinable frequency spectrum or the predefinable amplitude value and / or effective value of the "desired operating state" and the obtained frequency spectrum or the amplitude value obtained and / or effective value of the "actual operating state" are then used in the manner described for determining changes in the drive 101 compared.

As an example of a component of a mechanical system 103 a drive 101 shows 2 a gear 107 , here a pinion, with a gearing, which is in a "healthy" operating condition, in which all teeth are undamaged. In this "healthy" operating condition becomes for a the drive 101 supplied electric current to the influence of the pinion 107 To be assigned frequency spectrum measured, the example in 3 is reproduced. There is an amplitude A the frequency components of the measured current over the frequency f applied. In addition to a frequency component of high and shortened reproduced amplitude A at a fundamental frequency fg occur in the "healthy" operating condition of the pinion 107 only shares in frequency sidebands 138 with very low amplitudes A on.

In 4 is the pinion 107 according to 2 in a damaged operating condition, also referred to as damage condition, outlined. The damage here, for example, in a tooth damage, ie tooth breakage 139 , In this case, a tooth head is broken off and flanks of adjacent teeth of the pinion 107 also attacked. An example of a frequency spectrum, as is the case with the drive 101 with the damaged pinion 107 according to 4 for the drive 107 supplied electric current is measured in 5 reproduced in the same representation. Compared to the frequency spectrum 3 are the amplitudes of the proportions of the measured current in the frequency sidebands 138 significantly increased in this state of damage. The difference in the frequency spectra clearly indicates the change in the operating state of the drive 101 and triggers an error signal.

In addition to the above explained, from the DE 10 2015 210 911 A1 known detection of damage to rotating components of the drive, it is with the in the 7 to 12 also possible to detect damage to translationally moving components.

For example, mechanical damage to the linear axes can occur in press transfers, which can lead to failure of the entire system. This damage should be detected as early as possible and at low cost during operation. For this purpose, internal signals of the electric drive motor are also used for damage detection of these translationally moving components, so that no additional sensors must be provided.

The inventive method for detecting mechanical damage to translationally moving components of the drive, or the corresponding device 100 for condition monitoring also consists of a signal processing device 110 with a visualization unit 128 and connection to the control of the electric motor 102 , The signal processing device 110 , preferably a digital computer, has a memory unit in the design data of the monitored mechanics, for example, lengths and radii, and measured data of the motor current and the control difference of the speed are stored in the undamaged state of the mechanics, as in the program flowchart according to 12 shown.

About one on the digital computer 110 executable program while the motor current of one or more phases of the electric motor, the control difference of the speed, a distance (encoder signal or speed) and, if necessary, further signals read out. The current and the control difference of the speed are transformed from the time into the path range, so that signals sampled equidistantly over the traverse path of the linear axis are obtained from signals sampled in time, as in FIGS 7 to 10 shown. As a result, disturbing start-up and braking operations in the current signal are eliminated in an advantageous manner. The on the way related current signal is evaluated by a time-frequency analysis.

With this method, which is equivalent to a short-time Fourier transform, the frequency of the phase current over the path can be considered. For example, the Wigner-Ville distribution, the Choi-Williams distribution or the Butterworth distribution or similar methods could be used. The way is, for example, the travel of a linear axis. Damage such as tooth bursts can be detected by their broadband impulse excitation (all frequencies are present at a particular location). The damage is assigned to a component via the previously saved geometry data. If impact excitations occur at a distance of, for example, the pitch circle diameter of a pinion engaging in the rack, this tooth pattern can be assigned to a tooth eruption on the pinion on the basis of the known pitch circle diameter. Furthermore, the control difference of the speed is also to transform from the time into the path range. In case of damage, the actual speed of the engine deviates from the target speed for a short period of time. This control difference is another indicator of mechanical damage. By combining the two evaluations, the diagnostic reliability can be increased. In each case several measurements can be averaged to hide interference from noise and other signal interference. For the same purpose, the results can also be compared with a previously determined and stored "in order value" (OK value) so that effects already present in the state without damage (actually value) do not lead to misinterpretations. The aim of these analysis methods is to determine a characteristic value by means of predetermined limit values, which visualizes the state of the component in a simple manner. In addition, as needed, further useful for the condition monitoring variables can be read from the control unit of the electric motor, such as the temperature. For the detection of damage to drives in the dynamic range, the in 7 illustrated test run suitable. In this case, the electric motor is constantly accelerated to the middle of the 840 mm long rack in the embodiment. From the middle, it is brought to a standstill with the amount of equal negative acceleration to the end of the rack. The subsequent application of the time-frequency analysis of the motor current gives indications of the previously artificially introduced Teeth on the rack. When the damage is overrun, the mechanical system is triggered by shock. The impulse excitation contains all frequencies. Accordingly, broadband shock stimuli are to be expected at the damage sites, which can be assigned to the outbreaks of teeth. In the subsequent, in 8th shown evaluation irregularities in the movement of the transfer bar can be detected. The dominant frequency on the graph of 8th is the excitation frequency of the motor. This increases analogously to the speed constant to the middle of the rack. In the subsequent braking process, the amplitudes of the motor current are much smaller, which is why they are not shown in the illustration. After approx. 1400 ms the cycle starts again, the rack moves back again. At about 580 ms, a broadband excitation in the motor current can be seen. At this time, a separation point of the example consisting of two sections rack is run over. Due to the misalignment between the sections, there is a shock excitation of the pinion engaging in the rack, which affects the motor current and in the time frequency analysis ( 8th ) as well as in the time signal of the stream ( 7 ) is recognizable. The corresponding phase current and the speed over the path range of a driven by the rack carriage is in the 9 additionally shown.

10 shows a signal transformed from the time into the image area, which was evaluated by a Choi-Williams distribution. Due to a path constant sampling, the time-varying frequency of the motor current has a constant value. The X-axis shows the path over the rack.

In the 11 are once again the time-frequency analysis of the phase current and the evaluation of the control difference of the speed shown above each other, with at 195 mm, 462 mm and 728 mm tooth fractures ZA on pinion not shown in detail (pitch circle diameter 266mm) of the rack drive also not shown are arranged.

Here, the difference between the target and actual speed is increased at the known points of damage. The rash at 588 mm ( 11 ) is assigned to the separation point of the two rack parts. The negative deflection at 420 mm can be explained by the change from acceleration to braking mode. The rollover of the tooth eruption on the pinion at 195 mm can be clearly seen. The control difference at 462 mm (rollover of the teeth on the pinion) shows no greater value than the control differences in the immediate area, in which there is no mechanical damage.

Advantageously, a correlation of the two methods of investigation (time-frequency analysis and speed control difference in the drive) takes place, with increased damage being expected at the points where irregularities occur in both signals over several measurement series.

The special advantage of the in the 7 to 11 The method according to the present invention consists in the use of the time-frequency analysis for the detection of damage-caused shock excitation in the phase current and the comparison with the design data (eg lengths, diameters) instead of movement data. The imaging of mechanical shocks on the position of a linear axis (for example on a rack) is essential and particularly advantageous for reliable damage detection. The assignment of these shocks to a component takes place in an advantageous manner via its previously recorded geometry data. Due to the transformation of the signals from the time to the path range, the evaluation of the phase current is independent of time-varying conditions such as start-up or braking. The diagnostic reliability can be further increased by evaluating further drive-internal data, such as the control difference of the speed.

Alternatively, the phase currents could be determined by additional sensors and all axes to be monitored are traversed in a test run at constant speed. Instead of monitoring based on the motor current, the mechanical vibration could be detected and evaluated by acceleration sensors. However, this would again have the disadvantage that additional sensors and a corresponding evaluation peripherals are provided.

With the in the 7 to 12 shown and described method is thus a sensorless condition monitoring of linear axes during dynamic operation based on drive signals possible. The temporal decoupling of the phase current signal and the mapping to the travel of the linear axis allows a positionally accurate damage determination without disturbing temporal effects. By using the phase current signal, which is present in each regulated electric motor internally or can be easily determined, the inventive method can be applied to a variety of systems. The use in press transfer lines is particularly advantageous, but are also possible other drive systems that are driven by an electric motor, for example, other machine tools or electric vehicles.

LIST OF REFERENCE NUMBERS

100

contraption

101

drive

102

Phase machine

103

Mechanical system

104

camp

105

clutch

106

transmission

107

Gear; pinion

108

rack

109

measuring Equipment

110

Signal processing device

111

arrows

112

Measuring level of 110

113

First signal processing means for time-frequency analysis

114

Second signal processing means for amplitude and / or RMS determination

115

Signal connections from 112 to 113, 114

116

signal connection

117

First comparison means

118

signal connection

119

Second comparison means

120

First storage medium for the predefinable frequency spectrum

121

Second storage means for the predefinable amplitude values or RMS values

122

signal connection

123

signal connection

124

Signal generation means, here: Signal generation stage

125

Signal connection from 117 to 124

126

Signal connection from 119 to 124

127

notification means

128

Visualization means, here: visualization unit or display

129

Signal connection from 124 to 128

130

Means for delivering an audible warning signal

131

Signal connection from 124 to 130

132

control means

133

signal connection

134

recording means

135

Signal connections from 113, 114, 124 to 134

136

Signal connection from 113 to 120

137

Signal connection from 114 to 121

138

Frequency sidebands

139

tooth fracture

A

Amplitudes of the frequency components of the electric current

ZA

Teeth on the pinion

f

frequency

fg

fundamental frequency

U

Phase connection of 102

V

Phase connection of 102

W

Phase connection of 102

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 2013/017515 A1 [0003]
• DE 102013213046 A1 [0004]
• DE 102015210911 A1 [0005, 0056]

Claims (7)

A method for detecting deviations and / or changes in at least one operating state of an electrically, in particular electromotive, driven drive (101), in particular for detecting a presence and / or occurrence and / or development of damage, preferably mechanical damage, to such Drive (101) comprising the steps of: Measuring at least one electrical current supplied to the electrically operated drive (101) for supplying electrical energy, Performing a time-frequency analysis and / or an amplitude and / or RMS determination of the at least one measured electrical current, Comparing a frequency spectrum obtained from the time-frequency analysis of the at least one measured electrical current with a predefinable frequency spectrum and / or Comparing an amplitude value obtained from the determination of the amplitude and / or effective value and / or the effective value of the at least one measured electrical current with a predefinable amplitude value or effective value, the at least one sub-frequency spectrum and / or the amplitude and / or rms value of a specific type and / or location of a specific frequency-dependent deviation and / or change in at least one of the operating states, in particular a specific damage, of the electrical, in particular an electric motor driven drive (101), whereby this damage is caused to a translationally moving component of the drive (101), - Triggering of an error signal when a deviation of predeterminable size is determined when comparing won with predetermined frequency spectrum and / or amplitude value and / or effective value. Method according to Claim 1 , characterized in that the predeterminable frequency spectrum and / or the predefinable amplitude value and / or the presettable effective value are optionally preset as fixed values independently of the measured electrical current; - be obtained in at least one previous measurement; - be determined from a combination of fixed values with values obtained in at least one previous measurement; in particular from values obtained in at least one previous measurement, as long as these values do not exceed certain limit values by means of predefined values and are otherwise determined by these limit values. Method according to Claim 1 or 2 Characterized in - that the frequency spectrum obtained from the time-frequency analysis of a measured electric current in comparison with the predetermined frequency spectrum is examined for the presence of at least one part-spectrum of the frequency spectrum obtained of the at least, - wherein the at least one portion of frequency spectrum of a specific type and / or a specific location of a specific frequency-dependent deviation and / or change in at least one of the operating states, in particular a specific damage, of the electric, in particular electromotive, powered drive (101), - that from the presence of the at least one Part Frequency Spectrum a presence and / or occurrence and / or development of the particular type and / or the specific location of the particular frequency-dependent deviation and / or change in the at least one of the operating conditions, in particular the specific damage, the electric h, in particular electromotive, powered drive (101) is detected and - that a certain type and / or the specific location of the determined frequency-dependent deviation and / or change in the at least one of the operating conditions, in particular the specific damage (139), the electric , in particular electric motor, powered drive (101) is triggered characteristic error signal. Method according to Claim 1 . 2 or 3 , characterized in that - the amplitude value and / or effective value of the at least one measured electrical current obtained from the determination of amplitude and / or rms value compared to the predefinable amplitude value or effective value to a deviation and / or change, in particular increase, of the obtained amplitude value and / or RMS value is checked in relation to the predefinable amplitude value or RMS value, wherein the deviation and / or change, in particular increase, of the acquired amplitude value and / or RMS value relative to the predeterminable amplitude value or RMS value of a certain, of the amplitude value and / or RMS value Dependent deviation and / or change in at least one of the operating states of the electrically, in particular electromotive, driven drive (101) stems, in particular caused by a wear of the electric, in particular electromotive, driven drive (101) Deviation and / or change in at least one of the operating states of the electric, in particular electromotive, driven drive (101), that from the deviation and / or change, in particular increase, of the obtained amplitude value and / or effective value from the predefinable amplitude value or effective value, a presence and / or occurrence and / or development of the determined deviation dependent on the amplitude value and / or effective value and / or or alteration of the at least one of the operating states of the electrically, in particular electromotively, operated drive (101), in particular a presence and / or occurrence and / or development of the deviation caused by wear of the electrically, in particular electromotive, driven drive (101) and / or or change in the at least one of the operating states of the electrically, in particular electromotively, operated drive (101) is detected and - that a certain, depending on the amplitude value and / or effective value deviation and / or change of at least one of the operating states of the electric, in particular electromotive, driven drive (101), in particular the deviation caused by wear of the electrically, in particular electromotive, drive (101) and / or change in the at least one of the operating states of the electrically, in particular electromotive, driven drive (101), characteristic error signal triggered becomes. Method according to one or more of the preceding claims, characterized in that for distinguishing the deviation and / or change, in particular increase, of the obtained amplitude value and / or effective value of the at least one measured electrical current with respect to the predeterminable amplitude value or effective value of the at least one measured electrical Electric current, on the one hand, from further use of the electric, in particular electromotive, driven drive (101) with different setpoint values for amplitude value and / or effective value of the amplitude value and / or rms value of the at least one measured electrical current, other control data of the electric, in particular electromotive, operated Drive (101) are used, in particular further descriptive of the setpoint control data from a programmable logic controller of the electric, in particular elektrom otorisch powered drive (101). Method according to one or more of the preceding claims, characterized in that by the error signal, a message of a detected error, in particular a visualization of the detected error, and / or an intervention in an operation of the electrically, in particular electromotive, powered drive (101), in particular an at least partial shutdown of the electrically, in particular electromotive, operated drive (101), triggered and / or controlled. Device (100) for detecting deviations and / or changes, in particular for detecting a presence and / or an occurrence and / or a development of mechanical damage (139) on translationally moving components, in operating states of electric motor driven drives (101), at least comprising : - Measuring means (112) for measuring at least one at least one of the electrically driven drives (101) for supplying electrical energy supplied electric current, in particular measuring means (112) for at least almost continuous measurement of at least one instantaneous value of the at least one electrical current, - First signal processing means (113) for performing a time-frequency analysis of the at least one measured electric current and / or second signal processing means (114) for performing an amplitude and / or rms value determination of the at least one measured electrical current, - First comparison means (117) for comparing a in the first signal processing means (113) from the time-frequency analysis obtained frequency spectrum of the at least one measured electrical current with a predetermined frequency spectrum and / or second comparison means (119) for comparing an amplitude value obtained in the second signal processing means (114) from the amplitude and / or effective value determination and / or effective value of the at least one measured electrical current with a predefinable amplitude value or effective value, and - Signal generating means (124) for triggering an error signal when a deviation of predeterminable size is determined when comparing obtained with predetermined frequency spectrum and / or amplitude value and / or RMS value.

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