Method for determining the speed of an electric servomotor controlled by a pulse-width modulated signal and actuator

Abstract

Method for determining the speed of an electric servomotor (M) controlled by a pulse-width modulated signal, characterized by: a1) Determining the pulse-pause voltage applied to the servomotor (M) during a pulse pause of the pulse-width-modulated signal, wherein, to determine the pulse-pause voltage, an average value is formed from a plurality of sample values ​​of the pulse-pause voltage measured during several pulse pauses of the pulse-width-modulated signal, and a2) Determination of the speed as a function of the pulse-pause voltage determined during the pulse pauses.

Description

The invention relates to a method for determining the rotational speed of an electric servomotor controlled with a pulse-width-modulated signal.The invention further relates to an adjusting device which has an electric servomotor which is actuated with a pulse-width-modulated signal, and a rotational speed determination unit.DE 199 48 110 A1 shows a method and a device for detecting the rotational speed of an electric motor which is actuated with a PWM signal. In this case, in the event of an interruption of the control signal, a specific characteristic of the signal (e.g. the voltage) is determined, it being possible for the rotational speed of the motor which is dependent thereon to be determined by the characteristic of this signal.DE 10 2010 017 356 A1 discloses a direct current motor which is driven with a PWM signal.EP 1 727 273 A1 shows a device for feeding an actuating drive, wherein the energy consumption of the actuating drive can be optimized by a voltage control device.DE 198 34 108 A1 discloses a method for determining a motor speed in electric motors, wherein the speed is evaluated by evaluating the AC component superimposed on the DC component of the motor current. In this case, ripple occurring by detecting minimum and maximum values is determined.There is a need to determine the actual rotational speed of an electric servomotor controlled with a pulse-width-modulated signal in the simplest possible manner without additional sensor systems.This object is achieved with the method having the feature of claim 1 and the adjusting device having the features of claim 7. Advantageous embodiments are described in the dependent claims.For a method for determining the rotational speed of an electric servomotor controlled with a pulse-width modulated signal, it is proposed:determining the pulse pause voltage present at the servomotor at a pulse pause of the pulse-width-modulated signal, wherein, for determining the pulse pause voltage, an average value is formed from a plurality of sample values of the pulse pause voltage measured in a plurality of pulse pauses of the pulse-width-modulated signal, anddetermining the rotational speed as a function of the pulse pause voltage determined in the pulse pauses.The rotational speed determination is thus carried out by an analysis of the voltage signal during a plurality of pulse pauses. A pulse interval lies between two successive pulse voltages of the pulse-width-modulated signal. This pulse interval voltage is then not substantially determined by the driving PWM signal, but is suitable for evaluating rotational speed-dependent signal characteristics.It has been shown that the pulse interval voltage which is present at the position motor in such a pulse interval is dependent on the rotational speed. This pulse interval voltage is composed of a DC voltage component and an AC voltage component determined by ripple. To determine the pulse interval voltage, an average value is formed from a plurality of sampling values of the pulse interval voltage measured in a plurality of pulse intervals of the pulse width modulated signal.The mean value is formed from a plurality of sample values of the pulse pause voltage in a plurality of successive pulse pauses. Thus, at the end of each pulse interval, a sampling of the pulse interval voltage can be detected and the moving average value of the pulse interval voltage can be formed. This mean value can be determined from the maximum pulse pause voltage occurring during the pulse pause and the minimum pulse pause voltage.It has been shown that this level of the pulse interval voltage is dependent on the rotational speed.It is thus conceivable for the rotational speed to be determined as a value proportional to the pulse interval voltage.The pulse interval voltage also has ripple, however, which originates from the electromagnetic behavior of the servomotor during its rotation. The number of ripple occurring during the pulse interval in the signal present at the voltage terminals of the servomotor is a measure of the rotational speed of the servomotor.A complete revolution of a servomotor is thus characterized by a number N of ribs. By counting the number of ripple during the pulse pause and detecting the time interval between this determined number of ripple, it is possible to infer the rotational speed. It is thus conceivable in the pulse interval for the number of ripple which occurs during exactly one revolution to determine the elapsed time with the aid of the pulse interval voltage signal. However, it is also conceivable, knowing the pulse pause length, to count the number of ripple occurring in this pulse pause and to divide it by the constant number N of ripple required for one revolution and the pulse pause length, in order to calculate the rotational speed from this.In this way, the rotational speed can be determined in a simple manner without additional sensor systems only with a computing unit on the basis of the clamping voltage present at the servomotor.It is conceivable that a determination of sampling periods for sampling sampled values of the pulse interval voltage takes place as a function of the duty cycle of the pulse width modulated signal. The evaluation can then be adapted to the different signal conditions which occur at the different rotational speed ranges. The sampling rate can thus be adapted such that the frequency of the sampling period only collides with the ripple frequency outside the actually used rotational speed range.In this case, an alternating change of two defined sampling periods can take place in stages dependent on the duty cycle of the pulse-width-modulated signal. Sampling periods are provided for different duty cycle ranges.Between these different sampling periods, it is then possible, for example, to switch back and forth alternately with an increasing step of the duty cycle of the PWM signal.This is particularly advantageous if the speed is controlled by a change in the PWM in order to avoid aliasing problems. If, for example, only one measurement per pulse interval is performed at a time, the sampling period can be adapted by predefined steps if the PWM signal is changed. The PWM change serves, for example, to keep the rotational speed constant over a valve control range. A constant speed is important for the time-controlled positioning in relation to the total running time of the valve control range.The determination of the sampling periods can furthermore take place as a function of at least one speed threshold value. It is thus conceivable that a sampling period selected as a function of the duty cycle of the pulse width modulated signal is only used when the rotational speed exceeds a predefined rotational speed threshold value at which aliasing effects can occur when sampling the ripple voltage.The method can be used to set a valve of a building heating or air conditioning system with the servomotor as a function of the determined speed. The closing or opening angle of the valve can thus be determined as a function of the ascertained rotational speed. For this purpose, variable rotational speed sections can be integrated, for example. The ascertained rotational speed can, however, also be used for regulating the servomotor, for example in order to keep the rotational speed constant.The adjusting device has an electric servomotor which is actuated with a pulse-width-modulated signal, and a rotational speed determination unit. The rotational speed determination unit is then set up, for example by suitable programming, for carrying out the method mentioned above.The adjusting device can have an analog-to-digital converter for sensing the motor voltage present at the servomotor. This analog-to-digital converter is then connected to the rotational speed determination unit or integrated into the rotational speed determination unit. The analog-to-digital converter can be part of a microcontroller or microprocessor, for example, which, depending on the digital sample values in the output of the analog-to-digital converter during the pulse pause, determines the rotational speed from the sampled clamping voltage of the servomotor either directly depending on the sampled clamping voltage and an average value determined therefrom in a plurality of pulse pauses.The actuating device can additionally have a peak value detector for determining current or voltage ripple in pulse pauses of the pulse-width-modulated signal. The rotational speed can thus be determined as a function of time between a number of peak events, wherein a peak event in each case identifies the occurrence of a ripple.The adjusting device can have a valve of a building heating or air conditioning system that can be actuated by the servomotor. Thus, the adjusting device can be designed for regulating floor heating and can ensure precise regulation of the floor heating in an extremely precise and compact manner. The adjusting device can, however, also have a connecting connection for mechanically coupling the servomotor to such a separate valve.The rotational speed determination unit can furthermore be configured to determine a closing point as a function of a drop in the rotational speed and / or to regulate the rotational speed of the servomotor as a function of the determined rotational speed. The rotational speed determined can therefore not only be used further as an absolute value, but characteristic changes in rotational speed can still be detected and used for further regulation or control.In this case, for example, the speed drop at the transmission end stop of a control valve and the speed drop at the closing point can be evaluated and compared with one another. A difference between these two rotational speed drop values indicates assembly errors of the control valve, which can be reported to the user.The invention is described in more detail below with reference to the attached drawings with an exemplary embodiment. The following are shown: FIG. 1 is a circuit diagram of the servomotor with control and evaluation logic; FIG. 2 shows an example of a terminal voltage signal of a servomotor in a pulse interval of a pulse-width-modulated signal; FIG. 3 shows a diagram of the terminal voltage of a servomotor in the pulse interval with a first transient phase and a subsequent DC voltage phase.FIG. 1 shows a circuit diagram of an adjusting device 1 with an electric servomotor M. The servomotor M has two connection contacts ST 1, ST 2, to which a control signal is applied. The control signal is generated on the one hand with a DC voltage DC and on the other hand via a pulse width modulated signal PWM, which apply a respective series-connected transistor pair T 1, T 2 and T 3, T 4 via resistors R 1, R 2, R 3, R 4.The terminal voltage is tapped via a low-pass filter TP and fed to an analog-to-digital converter ADC. The digital output of the analog-to-digital converter ADC is integrated into a rotational speed determination unit μC or as part of this third determination unit μC.The cut-off frequency of the low-pass filter, which is formed, for example, by two resistors R 5, R 6 and a capacitor C 1 connected to ground, can lie, for example, in the range from approximately 2,000 to approximately 4,000 Hz. The limit values of the low-pass filter should be selected as a function of the frequencies of the servomotor or the permissible rotational speed limits.The rotational speed can now be determined during the pulse interval of the pulse-width-modulated signal PWM by evaluating the sampled digital signal at the connection terminals ST 1, ST 2 of the servomotor M or at the output of the low-pass filter TP. There, half the motor voltage is present independently of the rotational direction, so that the same analog-to-digital converter ADC can be used for both rotational directions. This can be done by suitable programming in the manner described below.For this purpose, FIG. 2 shows a diagram of the pulse interval voltage U present at the servomotor M in a pulse interval of the pulse-width-modulated signal over the time T. The pulse phases of the PWM pulses can be seen with the voltage U PWM. In the pulse pause lasting from time t 0 to line t 1 the pulse pause voltage U is characterized by a DC voltage component U_DC and a ripple component U_ ripple.The level of this pulse pause voltage is a measure of the actually present rotational speed of the servomotor M. This pulse pause voltage can be determined, for example, from the mean value of the maximum pulse pause voltage U_R+ detected during the pulse pause and the minimum pulse pause voltage U_R- as follows:However, at least one sampling of the pulse pause voltage can also take place in each pulse pause, preferably at the end after the end of the transient phase. According to the invention, the (e.g. moving) average value of the pulse pause voltages is formed over a plurality of pulse pause events in order to determine the rotational speed and / or the change in rotational speed therefrom.However, it is also conceivable that the rotational speed is determined by counting the number of ripple and measuring the time interval dt n required for this. For example, six ripple can occur in one revolution of 1n servomotor M. Then, in order to determine the rotational speed, only the time interval dt n which comprises exactly six ripple for one revolution has to be measured. The speed is then determined simply by the formula.The ripple component is also dependent on the engine speed. Thus, the rotational speed can be determined, for example, proportionally from the ripple voltage or preferably from the mean value of this ripple voltage.For the variants described above, there is a problem that after the current has been switched off and the PWM pause, the inductive properties of the motor winding are effective and generate a negative voltage. This voltage is reduced at different speeds depending on the engine speed. Only after this transient phase is the generator voltage applied to the motor. It is therefore appropriate to carry out the measurement only after the transient phase has elapsed.For this purpose, FIG. 3 shows an exemplary diagram of the terminal voltage U of the servomotor M in the pulse pause. The time period between the beginning of the pulse pause t 0 and the later time t 2 is the transient phase in which the induced negative voltage is reduced. At standstill, i.e. at the rotational speed n=0, this degradation phase t 2- t 0 takes the longest time. Only after the negative induction voltage has dissipated is the generator voltage applied to the servomotor M.However, it is also possible to determine this transient phase and to then draw conclusions as to the rotational speed. However, this transient phase is relatively short and can be measured very difficultly using digital sampling methods, in particular at high rotational speeds.To reduce measurement errors, it is recommended that the measurement of the pulse interval voltage explained in connection with FIG. 2 be carried out only approximately after the transient phase has elapsed. In particular, if the sampling takes place at the end of each pulse interval, the PWM stages should be selected such that the smallest possible aliasing effects occur.This can be done stepwise by matching the sampling periods to the PWM duration and the PWM ratio of pulse time to pause time, for example as follows:75 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms 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ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms3 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms25%15 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms1 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms4 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms20%The calculation of the PWM duration can be carried out independently of the PWM stage as follows:In the case of motors with very high speeds, however, it may be advisable under certain circumstances to change the sampling period from a constant sampling period to sampling periods which alternate stepwise only starting from a limit speed of, for example, 2500 rpm / min. At this speed, there are resonances with the ripple if the desired speed is about 2000 U / min. Therefore, PWM stages should be chosen which have their resonance (significantly) higher, so that there is no risk of measurement errors due to resonances (aliasing). The above-mentioned stages, in particular with a period of 5 ms, have resonances in the range of the desired rotational speed around 2000 U / min and lead to aliasing problems. The conversion of the sampling periods can be carried out, for example, as follows:34 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms3 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms1 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms75 %2500 U / min / min23 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms2 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms1 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms66 %3333 U / min / min12 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms1 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms1 ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms ms50 %5000 U / min / min

Claims

Method for determining the rotational speed of an electric servomotor (M) controlled with a pulse-width-modulated signal, characterized by: a1) determining the pulse pause voltage present at the servomotor (M) in a pulse pause of the pulse-width-modulated signal, wherein, for determining the pulse pause voltage, an average value is formed from a plurality of sample values of the pulse pause voltage measured in a plurality of pulse pauses of the pulse-width-modulated signal, and a2) determining the rotational speed as a function of the pulse pause voltage determined in the pulse pauses.Method according to Claim 1, characterized in that the rotational speed is determined as a value proportional to the pulse interval voltage.Method according to one of the preceding claims, characterized bysample periods for sampling samples of the pulse interval voltage as a function of the duty cycle of the pulse-width-modulated signal.The method of claim 3, characterized bychangering two fixed sampling periods in steps dependent on the duty cycle of the pulse width modulated signal.Method according to claim 3 or 4, characterized byrising the sampling periods further in dependence on at least one speed threshold.Method according to one of the preceding claims, characterized bya valve of a building heating or air conditioning system being connected to the servomotor as a function of the rotational speed determined.Actuating device having an electric servomotor (M) which is actuated with a pulse-width-modulated signal, and having a rotational speed determination unit (μC), characterized in that the rotational speed determination unit (μC) is set up to determine the pulse pause voltage present at the servomotor (M) in a pulse pause of the pulse-width-modulated signal, wherein, to determine the pulse pause voltage, an average value is formed from a plurality of sample values of the pulse pause voltage measured in a plurality of pulse pauses of the pulse-width-modulated signal, and to determine the rotational speed as a function of the pulse pause voltage determined in the pulse pauses.Actuating device according to Claim 7, characterized in that the actuating device has an analog-to-digital converter (ADC) for sampling the motor voltage present at the servomotor (M), the analog-to-digital converter (ADC) being connected to the rotational speed determination unit (μC) or being integrated into the rotational speed determination unit (μC).Actuating device according to Claim 7 or 8, characterized in that the actuating device has a valve, which can be actuated by the servomotor (M), of a building heating or air-conditioning system, in particular of a floor heater, or has a connection connection for mechanically coupling the servomotor (M) to such a separate valve.Actuating device according to one of Claims 7 to 9, characterized in that the rotational speed determination unit (μC) is furthermore set up to determine a closing point as a function of a drop in the rotational speed and / or to regulate the rotational speed of the servomotor (M) as a function of the determined rotational speed.

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