EP3960309A1 - Resonance method for a vibration system, a converter, an excitation unit and vibration system - Google Patents

Abstract

The invention relates to a resonance method (1) for an oscillating system (2) for resonantly oscillating an excitation unit (4) with an oscillating mass (3), comprising the steps of deflection detection (5), a deflection (x) of the oscillating mass (3), and speed generation (6) a speed (v) of the oscillating mass (3) by differentiating the deflection (x), a phase position generation (7) a mechanical phase position (θ_m) by means of the deflection (x) and the speed ( v), a phase position correction (8) of the mechanical phase position (θ_m) by means of a correction value (k_θ) to a corrected phase position (θ_k ), a frequency formation (9) of an electrical angular frequency (ω_el) by means of at least one P control based on the corrected phase position (θ_k), a phase position formation (10) of a electrical phase position (θ_el) by means of integration based on the electrical angular frequency (ω_el), a factor formation (11) of a correction factor (k_F) by means of a trigonometric function based on the electrical phase position (θ_el) and a setpoint application (12 ) a target excitation value (13) with the correction factor (k_F) to generate a corrected target excitation value (14). The invention also relates to a converter (20), an excitation unit (4) with the converter (20) and the oscillating system (2) with the excitation unit (4) and the oscillating mass (3).

Description

The invention relates to a resonance method for an oscillating system for resonantly oscillating an excitation unit with an oscillating mass. Furthermore, the invention relates to a converter, the excitation unit and the vibration system.

Industrial applications with an electromechanical excitation unit for generating vibrations of an oscillating mass, in which an oscillatable system, hereinafter referred to as an oscillating system, is to be excited with the oscillating mass in the range of a resonant frequency, generally require a determination or estimation of this resonant frequency or the production of the state of the resonant oscillation of the excitation unit and the oscillation mass to be set in oscillation in order to be able to control or regulate the operating behavior of the oscillation system in an energy-efficient, reliable and effortless manner.

In this case, the excitation unit usually includes electromagnets, which can be operated by means of electrical converters and cause the oscillating mass to oscillate based on inductive energy transmission.

Even small deviations in the resonant vibration of the excitation unit and vibration mass can lead to significant losses in energy efficiency/efficiency or the quality of the desired operating behavior/the reliability of the respective application.

Thus, the determination of the resonant frequency or the settled, resonant vibration state of the excitation unit and vibration mass, which was previously carried out separately from the actual operation, in corresponding machines and Devices used in production often have significant downtimes, which generally require additional effort for the respective production process and thus cause costs that are not negligible.

Such an oscillating system is used, for example, as a friction welding machine or oscillating conveyor.

The basic process of such a vibration system can be briefly outlined using the example of the friction welding machine. In order to weld a first workpiece to a second workpiece, the vibration mass, which has a first workpiece carrier and the first workpiece connected to it, is set into forced vibrations by means of an excitation unit. The oscillating mass is usually mounted so that it can swing by means of a spring device.

To generate the frictional heat for this production process, the first workpiece is rubbed against the second workpiece, which is connected to a generally stationary second workpiece carrier, until it welds.

If this excitation takes place at the resonant frequency, ie in vibrational resonance between the excitation unit and the vibration mass, the desired vibration can be generated with a particularly low expenditure of energy.

This resonant frequency of the vibration system is decisively determined by the vibration mass, which here includes the first workpiece, and the vibration-capable mounting of the vibration mass, ie the spring stiffness of the spring device used.

Since the first workpiece contributes to the vibration mass, after a workpiece change of the first tool, if the mass of the first workpiece in particular changes, the resonant frequency, ie the resonant frequency, has to be determined again Vibration state of the excitation unit and vibration mass is mandatory and required with considerable effort.

Otherwise, the vibration system does not work optimally, in particular in terms of energy, as a result of which its efficiency is greatly reduced or the desired vibration amplitude cannot be achieved and the required welding quality is rather poor.

Previous applications, such as friction welding, mainly use pre-operative methods to determine/estimate the resonance frequency in order to then excite the vibration mass using the excitation unit and achieve the required resonant vibration state of the excitation unit and vibration mass.

The desired resonant frequency is determined by means of an independent run-up test before the actual production process and then operated with it until a new run-up attempt becomes necessary due to the use of a new first workpiece or unwanted deviations in the production process that have occurred in the meantime make a correction necessary.

This means that the vibration is only excited here on the basis of the frequency determined by the run-up test, which corresponds to the resonance frequency required in the actual production process for the resonant vibration state of the excitation unit and vibration mass, which also changes during the Operation in the production process can change, often only insufficiently.

The invention is therefore based on the object of proposing a resonance method, a converter, an excitation unit and an oscillating system which have a required resonant oscillation state for the resonant oscillation of the excitation unit with an oscillating mass of the oscillating system continuously determined during production and the vibration system is operated with it.

The object is achieved by a resonance method with the features specified in claim 1, by a converter according to the features specified in claim 9, by an excitation unit with the converter according to the features specified in claim 12 and a vibration system with the excitation unit according to the features specified in claim 14 features resolved.

A resonance method for an oscillating system for resonantly oscillating an excitation unit with an oscillating mass is proposed for solving the task, comprising the steps of deflection detection of a deflection of the oscillating mass, speed formation of a speed of the oscillating mass by differentiating the deflection, phase position generation of a mechanical phase position by means of the deflection and the speed, a phase position correction of the mechanical phase position by means of a correction value to a corrected phase position, a frequency formation of an electrical angular frequency by means of at least one P control based on the corrected phase position, a phase position formation of an electrical phase position by means of integration based on the electrical angular frequency, a factor formation of a Correction factor by means of a trigonometric function based on the electrical phase position and a setpoint application of an excitation ing setpoint with the correction factor to generate a corrected excitation setpoint.

The method is advantageously based on the intellectual restriction of the freedom of movement (the degree of freedom) of the oscillating mass and on its resonant frequency (here the electrical circular frequency) compared to the excitation unit.

wobei v die Geschwindigkeit, x die erfasste Auslenkung und t die Zeit ist.For this purpose, the actual position of the deflection of the oscillating mass detected by means of the deflection detection is converted into a vector, the abscissa is the detected deflection and the ordinate is the speed of the oscillating mass formed by means of the speed formation as a differentiation of the deflection according to the formula $$\mathrm{v}\left(\mathrm{t}\right)=\frac{\mathrm{dx}}{\mathrm{German}}$$

where v is the velocity, x is the detected displacement, and t is the time.

wobei θ_m die mechanische Phasenlage, v die Geschwindigkeit und x die Auslenkung ist.The mechanical phase position generated by the phase position generation is advantageously obtained, for example, by means of an arctan2 function based on the deflection and the speed according to the formula $$\mathrm{\theta m}=\arctan \mathrm{2}\left(\mathrm{x},\mathrm{v}\right)$$

where θ _m is the mechanical phase position, v is the velocity and x is the displacement.

A normalized speed for generating the mechanical phase positions is preferably selected as the speed.

By means of the phase position correction of the mechanical phase position, the corrected phase position results continuously in an advantageous manner by means of a correction value.

Instead of P control (with gain component K _p ), PI control (with gain component K _p and integral component I) or PID control (with gain component K _p , integral component I and differentiation component D) can also be used for frequency formation of the circular electrical frequency. can be used on the basis of the corrected phase angle, which can increase the P control qualitatively in the sense of more control quality.

The electric circular frequency that is formed is also to be understood as the current oscillation frequency (requested resonance frequency) or last current oscillation frequency (last requested resonance frequency). Targeted programming of the control is therefore not necessary.

The electrical angular frequency is integrated in an advantageous manner for the phase position formation of the electrical phase position.

wobei k_F der Korrekturfaktur und θ_el die elektrische Phasenlage ist.The correction factor is factored using the trigonometric function on the basis of the electrical phase position, for example using a sine function according to the formula $$\mathrm{kF}=\sin \left(\mathrm{\theta el}\right)$$

where k _F is the correction factor and θ _el is the electrical phase position.

By applying the setpoint value, the excitation setpoint as an electrical value for a vibration-generating force of the excitation unit for exciting the oscillating mass is advantageously corrected with the correction factor, such that a corrected electrical value for the vibration-generating force is generated as a corrected excitation setpoint for the resonant oscillation to be achieved by the excitation unit and oscillating mass will.

With this corrected setpoint excitation value, for example, an electromagnet is electrically excited by the excitation unit, which generates the corresponding resonant oscillation of the excitation unit and oscillation mass.

Advantageous embodiments of the resonance method are specified in the dependent claims.

In a first advantageous embodiment of the resonance method, the resonance method has the step of speed normalization of the speed using the electrical circular frequency to a normalized speed, the speed being divided by the electrical circular frequency.

wobei v_n die normierte Geschwindigkeit, ω_el die elektrische Kreisfrequenz, x die Auslenkung und t die Zeit ist.In order to advantageously map the speed onto the angular electrical frequency, the speed is converted into the normalized speed on the basis of the angular electrical frequency according to the formula $$\mathrm{vn}\left(\mathrm{t}\right)=\frac{1}{\mathrm{\omega el}}\ast \frac{\mathrm{dx}}{\mathrm{German}}$$

where v _n is the normalized velocity, ω _el is the electrical angular frequency, x is the deflection and t is the time.

In a further advantageous embodiment of the resonance method, the correction value for the phase position correction is the returned electrical phase position, and the returned electrical phase position is preferably subtracted from the mechanical phase position.

From the point of view of regulation, a corrected phase position is thus established, with the mechanical phase position being corrected until the corrected phase position assumes a value of approximately 0.

The electrical phase angle fed back as a correction value to the mechanical phase angle in a control loop can also be added to the mechanical phase angle, taking into account the sign of the mechanical phase angle and the electrical phase angle.

In a further advantageous embodiment of the resonance method, an initial Specified angular frequency or last known electrical angular frequency used.

In order to initialize the resonance method, e.g. at the start of it, the initial circular frequency can preferably be specified as a parameter, for example, which can already correspond to the desired resonance frequency.

It is also advantageously possible, e.g. in the event of faults or a restart of the control after a failure of the resonance process, to fall back on the last known electrical circular frequency.

In a further advantageous embodiment of the resonance method, the mechanical phase position is determined in particular between a deflection amplitude of the deflection and the speed or between a deflection amplitude of the deflection and the deflection.

wobei x_a die Auslenkungsamplitude, x die Auslenkung und v die Geschwindigkeit ist.The deflection amplitude can be found according to the formula $$\mathrm{xa}=\sqrt{{\mathrm{x}}^{\mathrm{2}}+{\mathrm{v}}^{\mathrm{2}}}$$

where x _a is the deflection amplitude, x is the deflection and v is the velocity.

The normalized speed for determining the deflection amplitude is preferably selected as the speed.

In a further advantageous embodiment of the resonance method, a deflection signal is detected by a deflection measuring device for deflection detection and the deflection signal is corrected by a direct component depending on the installation location of the deflection measuring device with respect to the vibration mass DC component parameters are specified or determined by a DC component high-pass filter.

The deflection measuring device measures the deflection of the oscillating mass compared to a rest position of the oscillating mass and provides the deflection in the deflection signal for further processing by the resonance method.

The measured deflection value of the deflection associated with the deflection signal can be corrected by means of the direct component parameter or the direct component high-pass filter with regard to the installation location of the deflection measuring device.

In a further advantageous embodiment of the resonance method, the desired excitation value is a desired current and the corrected desired excitation value is a corrected desired current.

The excitation target value as an electrical value for the vibration-generating force and the corrected excitation target value as a corrected electrical value for the vibration-generating force for controlling the electromagnets, e.g. by means of an electrical converter, are each advantageously designed as a target current for generating a force-generating vibration excitation. In principle, a corresponding setpoint voltage is also suitable in each case.

In a further advantageous embodiment of the resonance method, the electrical circular frequency is monitored for disturbances during the resonant oscillation of the excitation unit and oscillation mass for disturbance monitoring.

For this purpose, the electrical circular frequency can advantageously be monitored by means of a lower frequency limit for falling below the electrical circular frequency and/or an upper frequency limit for falling below the electrical circular frequency.

To solve the problem, a converter is also proposed, which has a detection means, designed to detect a deflection of a deflection of the oscillating mass, a first generating means, designed to generate a speed of the oscillating mass by differentiating the deflection, a generating means, designed to generate a phase position of a mechanical phase position using the deflection and the speed, a correction means, designed to correct the phase position of the mechanical phase position by means of a correction value to a corrected phase position, a second means of formation, designed to form an electrical angular frequency by means of at least one P controller on the basis of the corrected phase position, a third means of formation, designed to Phase position formation of an electrical phase position by means of integration on the basis of the electrical angular frequency, a fourth formation means, designed for factor formation of a correction factor by means of a trigonometric function on the basis of the electrical phase position and an application means, designed to apply the correction factor to a target value of an excitation target value in order to generate a corrected excitation target value.

In a first advantageous embodiment of the converter, the converter has a normalization means designed for speed normalization of the speed using the electrical circular frequency to a normalized speed, the speed being divisible by the electrical circular frequency.

In a further advantageous embodiment of the converter, the returned electrical phase position is provided as a correction value for the phase position correction and the returned electrical phase position can preferably be subtracted from the mechanical phase position.

In principle, the converter is designed to carry out the resonance method according to the invention as described above.

To solve the problem, an excitation unit is also proposed, which has at least one electromagnet for exciting the oscillating mass, the converter according to the invention for operating the at least one electromagnet, and a deflection measuring device for measuring the deflection of the oscillating mass compared to a rest position of the oscillating mass.

The deflection measured by the deflection measuring device is transmitted by a deflection signal to the detection means of the converter for deflection detection.

In an advantageous embodiment of the excitation unit, the excitation unit has at least one spring element, with the at least one spring element being connected to the vibration mass.

Solutions with two or more spring elements are also conceivable here, by means of which the oscillating mass is oscillatingly mounted.

To solve the problem, an oscillating system is also proposed which has the excitation unit according to the invention and the oscillating mass.

In an advantageous embodiment of the vibration system, the vibration system is designed as a friction welding device or as a transport device.

Transport devices are, for example, conveyor devices for material transport (so-called vibrators or oscillating conveyors), which transport their goods on conveyor belts that are set in motion.

FIG 1

ein Struktogramm des erfindungsgemäßen Resonanzverfahrens,

FIG 2

eine schematische Regelungsdarstellung des erfindungsgemäßen Resonanzverfahrens und

FIG 3

eine schematische Darstellung einer Reibschweißvorrichtung mit dem erfindungsgemäßen Umrichter, der erfindungsgemäßen Anregungseinheit und dem erfindungsgemäßen Schwingungssystem.

The characteristics, features and advantages of this invention described above and the manner in which they are achieved will become clearer and more clearly understood in context with the following description of the exemplary embodiments, which are explained in more detail in connection with the figures. It shows:

FIG 1

a structogram of the resonance method according to the invention,

FIG 2

a schematic control representation of the resonance method according to the invention and

3

a schematic representation of a friction welding device with the converter according to the invention, the excitation unit according to the invention and the vibration system according to the invention.

the FIG 1 shows a structogram of the resonance method 1 according to the invention with method steps for resonant oscillation of an excitation unit with an oscillating mass.

During deflection detection 5, a deflection of the oscillating mass is detected. A deflection signal detected by a deflection measuring device for this purpose can be corrected by a DC component depending on the installation location of the deflection measuring device relative to the vibration mass, with the DC component being specified by a DC component parameter 34 or determined by a DC component high-pass filter 19.

By differentiating the deflection, a speed of the oscillating mass is formed during speed formation 6, the speed being converted into a normalized speed on the basis of the electrical circular frequency by dividing the speed by the electrical circular frequency.

During phase position generation 7, a mechanical phase position is generated on the basis of the deflection and the speed.

The phase position correction 8 converts the mechanical phase position into a corrected phase position by means of a correction value. In this case, the correction value is the electrical phase angle fed back in a control loop, the electrical phase angle fed back preferably being subtracted from the mechanical phase angle.

A frequency formation 9 of an electrical circular frequency takes place by means of at least one P control based on the corrected phase position. For the frequency formation 9, the P control can also be in the form of a PI control or a PID control.

For a process initialization 16, an initial circular frequency can be specified or the last known electrical circular frequency can be used.

Furthermore, the electrical circular frequency can be monitored for disturbances in the resonant oscillation of the excitation unit and oscillation mass for a disturbance monitoring 33 . Typical faults can be caused, for example, by mechanical defects when the vibration mass vibrates, so that the required circular electrical frequency can be too low or too high and the resonance process may have to be stopped.

In the phase position formation 10 of an electrical phase position, an integration takes place on the basis of the electrical angular frequency.

During factor formation 11 of a correction factor, a trigonometric function based on the electrical phase angle is used and the correction factor corrects an excitation setpoint to a corrected excitation setpoint during setpoint application 12 .

In FIG 2 a schematic control representation of the resonance method 1 according to the invention is shown. In this case, the resonance method 1 can be carried out by a converter, in particular by a control unit of the converter.

A detection means 21 is designed to detect a deflection 5 of a deflection x of the oscillating mass. A deflection signal detected as deflection x by a deflection measuring device is corrected by a direct component by a direct component high-pass filter 19 by a high-pass filter 37 depending on the installation location of the deflection measuring device relative to the vibration mass.

A first formation means 22 differentiates the deflection x by means of the speed formation 6 to a speed v of the oscillating mass. The speed v is further converted into a normalized speed v _n by a normalization means 35 in a speed normalization 15 on the basis of a returned angular electrical frequency ω _el by dividing the speed v by the angular electrical frequency ω _el .

A generating means 23 is designed for phase position generation 7 of a mechanical phase position θ _m , which takes place on the basis of the deflection x and the speed v.

A correction means 24 is designed for the phase position correction 8 of the mechanical phase position θ _m , the mechanical phase position θ _m being converted into a corrected phase position θ _k by means of a correction value k _θ . A returned electrical phase position θ _el is used as the correction value k _θ , the returned electrical phase position θ _el being subtracted from the mechanical phase position θ _m .

A second formation means 25 is designed for frequency formation 9 of the angular electrical frequency ω _el by means of a P control, which can also be a PI control or a PID control, on the basis of the corrected phase angle θ _k . the electrical angular frequency ω _el is returned to the normalization means 35 for the speed normalization 15 at this point.

An initial circular frequency ω _in can be specified by an initialization means 36 for method initialization 16 .

A phase position 10 of the electrical phase position θ _el is formed by a third formation means 26 by means of integration on the basis of the electrical angular frequency ω _el . At this point, the electrical phase angle θ _el is fed back to the correction means 24 for the phase angle correction 8 .

A factor formation 11 of a correction factor k _F is carried out by a fourth formation means 27 by means of a trigonometric function on the basis of the electrical phase angle θ _el .

An application means 28, designed to apply a setpoint value 12 to an excitation setpoint 13 in the form of a setpoint current I _s with the correction factor k _F , generates a corrected excitation setpoint 14 in the form of a corrected setpoint current I _sk . In particular, an electromagnet, which is included in the excitation unit and excites the oscillating mass to resonant oscillation, is operated with this corrected setpoint current I _sk .

means 3 a schematic representation of a friction welding device 32 with the converter 20 according to the invention, the excitation unit 4 according to the invention and the vibration system 2 according to the invention is shown.

The vibration system 2 is designed here, for example, as a friction welding device 32 with the excitation unit 4 and an oscillating mass 3 .

A first fastening means 41 for a first workpiece 43 is arranged on the vibration mass 3 . The oscillating mass 3 with the first fastening means 41 and the first workpiece 43 is mounted so as to be able to oscillate.

A second workpiece 44 is connected to a second fastening means 42 directly opposite the first workpiece 43 . The second workpiece 44 on the second fastening means 42 is firmly fixed in relation to the first workpiece 43 and is not mounted so that it can swing.

The excitation unit 4 for exciting vibrations in the oscillating mass 3 comprises the converter 20, an electromagnet 29, another electromagnet 30, a first and second spring element 38, 39 for the oscillating mounting of the oscillating mass 3, a deflection measuring device 18 and a deflection measuring device 18 connected to the converter 20 transmitted deflection signal, which has a measured actual value of the deflection.

The deflection is measured by means of the deflection measuring device 18 in relation to a rest position 31 of the oscillating mass 3.

The control method according to the invention can be carried out by means of the converter 20, in particular by means of the control unit 40 of the converter 20.

During operation of the friction welding device 32 , the first workpiece 43 fastened to the first fastening means 41 of the vibration mass 3 is set in resonant vibrations with the excitation unit 4 . The first workpiece 43, which is set in motion, rubs against the firmly fixed and non-vibrating second workpiece 44, with frictional heat being generated and the two workpieces 43, 44 being welded to one another in an energy-efficient manner and with high manufacturing quality.

Claims (15)

Resonance method (1) for an oscillating system (2) for resonantly oscillating an excitation unit (4) with an oscillating mass (3), comprising the steps - Deflection detection (5) of a deflection (x) of the oscillating mass (3), - Speed formation (6) of a speed (v) of the oscillating mass (3) by differentiating the deflection (x), - Phase position generation (7) of a mechanical phase position (θ _m ) by means of the deflection (x) and the speed (v), - phase position correction (8) of the mechanical phase position (θ _m ) by means of a correction value (k _θ ) to a corrected phase position (θ _k ), - Frequency generation (9) of an electrical circular frequency (ω _el ) by means of at least one P control based on the corrected phase position (θ _k ), - Phase position formation (10) of an electrical phase position (θ _el ) by means of integration based on the electrical angular frequency (ω _el ), - Factor formation (11) of a correction factor (k _F ) by means of a trigonometric function based on the electrical phase position (θ _el ) and - Application of the reference value (12) to an excitation reference value (13) with the correction factor (k _F ) to generate a corrected excitation reference value (14). Resonance method (1) according to Claim 1, having the step of speed normalization (15) of the speed (v) by means of the electrical angular frequency (ω _el ) to a normalized speed (v _n ), the speed (v) being divided by the electrical angular frequency (ω _el ) is divided. Resonance method (1) according to one of Claims 1 or 2, the correction value (k _θ ) for the phase position correction (8) being the returned electrical phase position (θ _el ) and preferably the returned electrical phase position (θ _el ) from the mechanical phase position (θ _m ) is subtracted. Resonance method (1) according to one of the preceding claims, wherein an initial circular frequency (ω _in ) is specified for method initialization (16) or the last known electrical circular frequency (ω _el ) is used. Resonance method (1) according to one of the preceding claims, wherein the mechanical phase position (θ _m ) between a deflection amplitude (x _a ) of the deflection (x) and the speed (v) or as a phase position between a deflection amplitude (x _a ) of the deflection (x ) and the deflection (x) is determined. Resonance method (1) according to one of the preceding claims, wherein for deflection detection (5) a deflection signal (17) is detected by a deflection measuring device (18) and the deflection signal (17) depending on the installation location of the deflection measuring device (18) relative to the oscillating mass (3). a DC component is corrected, the DC component being specified by a DC component parameter (34) or determined by a DC component high-pass filter (19). Resonance method (1) according to one of the preceding claims, in which the desired excitation value (13) is a desired current (I _s ) and the corrected desired excitation value (14) is a corrected desired current (I _sk ). Resonance method (1) according to one of the preceding claims, wherein the electrical circular frequency (ω _el ) is monitored for disturbances in the resonant oscillation of the excitation unit (4) and oscillation mass (3) for disturbance monitoring (33). Inverter (20), comprising - a detection means (21), designed for deflection detection (5) of a deflection (x) of the oscillating mass (3), - a first formation means (22), designed for speed formation (6) of a speed (v) of the oscillating mass (3) by differentiating the deflection (x), - a generating means (23), designed to generate the phase position (7) of a mechanical phase position (θ _m ) by means of the deflection (x) and the speed (v), - a correction means (24), designed for the phase position correction (8) of the mechanical phase position (θ _m ) by means of a correction value (k _θ ) to a corrected phase position (θ _k ), - a second formation means (25), designed for frequency formation (9) of an electrical circular frequency (ω _el ) by means of at least one P control based on the corrected phase position (θk), - A third formation means (26), designed to form the phase position (10) of an electrical phase position (θ _el ) by means of integration on the basis of the electrical angular frequency (ω _el ), - A fourth formation means (27), designed for factor formation (11) of a correction factor (k _F ) by means of a trigonometric function based on the electrical phase position (θ _el ) and - An application means (28) designed to apply a setpoint (12) to an excitation setpoint (13) with the correction factor (k _F ) to generate a corrected excitation setpoint (14). Converter (20) according to Claim 9, having a normalization means (35) designed for speed normalization (15) of the speed (v) by means of the electrical angular frequency (ω _el ) to a normalized speed (v _n ), the speed (v) being the electrical angular frequency (ω _el ) is divisible. Converter (20) according to one of Claims 9 or 10, in which the returned electrical phase position (θ _el ) is provided as the correction value (k _θ ) for the phase position correction (8) and preferably the returned electrical phase position (θ _el ) differs from the mechanical phase position (θ _m ) is subtractable. Excitation unit (4) comprising - at least one electromagnet (29) for exciting the oscillating mass (3), - A converter (20) according to any one of claims 9 to 11 for operating the at least one electromagnet (29) and - A deflection measuring device (18) for measuring the deflection (x) of the oscillating mass (3) relative to a rest position (31) of the oscillating mass (3). Excitation unit (4) according to Claim 12, having at least one spring element (38), the at least one spring element (38) being connected to the oscillating mass (3). Vibration system (2), having an excitation unit (4) according to one of Claims 12 or 13 and the vibration mass (3). Vibration system (2) according to Claim 14, prepared as a friction welding device (32) or as a transport device.

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