EP1387087B1 - Method for determining the flow rate in a pump - Google Patents

Method for determining the flow rate in a pump Download PDF

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Publication number
EP1387087B1
EP1387087B1 EP20030009647 EP03009647A EP1387087B1 EP 1387087 B1 EP1387087 B1 EP 1387087B1 EP 20030009647 EP20030009647 EP 20030009647 EP 03009647 A EP03009647 A EP 03009647A EP 1387087 B1 EP1387087 B1 EP 1387087B1
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EP
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Prior art keywords
pump
flow rate
motor
induced voltage
determined
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EP20030009647
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German (de)
French (fr)
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EP1387087A3 (en
EP1387087A2 (en
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Björn Kiffer
Frank Tolksdorf
Klaus Heinrich
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Wilo SE
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Wilo SE
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    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
    • F04D—NON-POSITIVE-DISPLACEMENT PUMPS
    • F04D15/00—Control, e.g. regulation, of pumps, pumping installations or systems
    • F04D15/0088—Testing machines

Definitions

  • the invention relates to a method for determining the flow rate of a fluid through a pump, in particular by means of a pump driven by means of a permanently excited, synchronized field-driven synchronous motor.
  • the invention further relates to a pump for conveying fluid, with which the method can be carried out.
  • the object of the invention is therefore to provide a method or a pump by means of which the flow rate of a fluid through a pump, in particular a driven by a permanently excited, synchronized motor synchronous motor driven pump, is reliably determined.
  • This object is achieved according to the present invention in that in the pumping operation of the motor, in particular the permanently excited, rotating field-driven synchronous motor, at least temporarily, in particular periodically, is switched off by the electric / electronic drive. In the switched-off state, the voltage induced in the pump motor, in particular in the synchronous motor, can then be detected and the flow rate of the fluid can be determined from the detected induced voltage.
  • the inventive method or the pump of the invention makes use of the consideration that a motor can be used not only by electric drive as a motor but also vice versa as a generator. This applies in particular to permanent-magnet field-wound synchronous motors.
  • a motor can be used not only by electric drive as a motor but also vice versa as a generator.
  • In motors upon rotation of the rotor from the outside at the stator terminals an induction voltage can be tapped, which is caused by the rotation of the rotor. This applies in particular to permanent-magnet field-wound synchronous motors.
  • the invention is further based on the consideration that different flow rates in a pump driven by a motor have an influence on the time course of the generator-induced voltage.
  • the engine for. B. the permanent magnet synchronous motor, which can be driven by a frequency controlled regulated off by the driving electronics at least for a predetermined time interval, so that then preferably from the time course of the detected induced voltage, the flow rate can be determined.
  • the determination may e.g. by comparison with reference characteristic curves, characteristic maps, or characteristic values.
  • the induced, in particular at the stator terminals sloping voltage can be recorded, for example, by an analog-to-digital converter.
  • This can e.g. be housed in a permanently excited synchronous motor in a microcontroller, which preferably also takes over the control of the inverter in the frequency converter for driving.
  • the engine comes slower or faster depending on the current flow rate to a halt, if not already before reaching the standstill of the engine would be turned on again.
  • the time profile of the recorded, for example, stored in a buffer memory induced voltage is characteristic of the flow rate, especially at the time of shutdown.
  • the flow rate for example, from the decrease in the induced voltage after the detection and, if appropriate, intermediate storage of the time profile of the induced voltage, if appropriate until the motor comes to a standstill.
  • the decrease in the induced voltage can be determined particularly advantageously by the time profile of the envelope of the detected induced voltage.
  • the detected voltage or the detected temporal voltage curve can be used to determine the phase position, for example. with a reference curve, i. be determined as a reference stored voltage characteristic.
  • a reference characteristic or, if appropriate, also a reference characteristic can e.g. be kept in a memory of the engine electronics for such a comparison.
  • the decrease in the frequency of the induced generator voltage is also a measure of the flow rate. Therefore, according to the invention, it is possible to determine from the recorded induced voltage curve the time interval of the individual voltage peaks, that is to say the frequency, and in particular from the change of the frequency, for example. to determine the flow rate between successive pairs of stress peaks.
  • a pump with which such a method can be carried out, accordingly contains a circuit by means of which the detected induced voltage, in particular the temporal voltage curve and / or values derived therefrom, are comparable to a stored reference characteristic, a reference characteristic field or reference values.
  • the flow rate it may be provided to switch off the motor with a suitable motor control at a specific time and to record the time course of the generator voltage then induced until the motor is at standstill and optionally store it.
  • Such a temporal measuring interval can be kept so short that a sufficiently reliable determination of the flow rate is possible without the pump losing significant speed. For example, it may be sufficient that the pump is switched off only over a period of a few induced voltage peaks, for example 2 to 10 voltage peaks.
  • the pump When the pump is switched back on after the predetermined time interval, it is preferably provided in synchronous motors that the rotary field to be newly applied by the frequency converter to the synchronous motor is first synchronized to the motor, since it lags the original driving rotary field due to the braking effect of the fluid.
  • the required new rotary field for connection to the synchronous motor is determined from the previously detected induced voltage, in particular from the temporal voltage curve. For example, from the temporal Course of the detected induced voltage to the required frequency and phase of the rotating field to be closed.
  • FIG. 1 shows the typical time course of induced voltages that can be tapped after switching off the driving rotary field on a permanent magnet synchronous motor, for example.
  • Two measurement curves 1 and 2 are shown here, whereby it can be seen that the time course of the two measurement curves, which were recorded at different flow rates, differ from one another.
  • From the recorded measuring curves can be, for example the different phase position relative to a reference characteristic or in the present image here e.g. of the second measurement curve 2 relative to the first measurement curve 1.
  • the FIG. 1 also shows the possibility of also infer from the change in frequency of the recorded voltage curve to a flow rate. So is in the FIG. 1 shown as an example for the voltage curve 1 that between a first pair of voltage peaks first a time .DELTA.t 1 can be determined, wherein between a following pair of voltage peaks, a time .DELTA.t 2 is measured.
  • the change in the time between the two measured values ⁇ t 1 and ⁇ t 2 which also simultaneously represents the frequency change, can also be deduced from the flow rate, for example by comparison with reference values, which can likewise be stored in a memory.
  • the method and / or a pump for carrying out the method without providing a further measuring device, it is possible to determine the current flow rate of a fluid, e.g. Water to be closed by the pump.
  • a fluid e.g. Water
  • the method or such a pump is accordingly very cost-effective and economical, since essentially the method according to the invention can be implemented by software in the motor control, that is, for example, in the microcontroller of the frequency converter of a synchronous motor.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Control Of Non-Positive-Displacement Pumps (AREA)
  • Control Of Positive-Displacement Pumps (AREA)
  • Control Of Ac Motors In General (AREA)

Description

Die Erfindung betrifft ein Verfahren zur Bestimmung der Durchflussmenge eines Fluids durch eine Pumpe, insbesondere durch eine mittels eines permanent erregten, drehfeldbetriebenen Synchronmotors angetriebene Pumpe. Die Erfindung betrifft weiterhin eine Pumpe zur Förderung von Fluid, mit der das Verfahren durchgeführt werden kann.The invention relates to a method for determining the flow rate of a fluid through a pump, in particular by means of a pump driven by means of a permanently excited, synchronized field-driven synchronous motor. The invention further relates to a pump for conveying fluid, with which the method can be carried out.

Es ist bekannt, siehe z.B. EP 877 463 die Durchflussmenge eines Fluids durch eine Pumpe, beispielsweise von Wasser durch eine Heizungspumpe anhand der elektrischen Leistungsaufnahme der Pumpe zu ermitteln. Dieses ist insbesondere im Bereich kleinerer Pumpenleistungen möglich, da in diesem Bereich die Durchflussmenge im wesentlichen linear mit der elektrischen Leistung der Pumpe skaliert.It is known, see eg EP 877 463 To determine the flow rate of a fluid through a pump, such as water through a heating pump based on the electrical power consumption of the pump. This is particularly possible in the range of smaller pump powers, since in this area the flow rate scales substantially linearly with the electric power of the pump.

Bei höheren elektrischen Pumpenleistungen weist die Kennlinie (elektrische Leistung P über Durchflussmenge Q) jedoch eine nur noch sehr flache Steigung auf bzw. nimmt sogar wieder ab. In diesem Bereich ist eine zuverlässige Ermittlung der Durchflussmenge eines Fluides durch die Pumpe lediglich anhand der elektrischen Leistung schwierig bzw. sehr ungenau.At higher electrical pump powers, however, the characteristic (electrical power P via flow rate Q) has only a very flat slope or even decreases again. In this area, a reliable determination of the flow rate of a fluid through the pump is only difficult or very inaccurate based on the electrical power.

Es ist weiterhin bekannt, in einem Fluid-Kreislauf bzw. in einer Pumpe zusätzliche Vorrichtungen vorzusehen, mit denen die aktuelle Durchflussmenge eines Fluids messtechnisch bestimmt werden kann. Die Anordnung einer solchen zusätzlichen Vorrichtung ist jedoch material- und kostenintensiv.It is also known to provide additional devices in a fluid circuit or in a pump, with which the current flow rate of a fluid can be determined by measurement. However, the arrangement of such an additional device is material and cost intensive.

Aufgabe der Erfindung ist es daher, ein Verfahren bzw. eine Pumpe zur Verfügung zu stellen, mittels der die Durchflussmenge eines Fluides durch eine Pumpe, insbesondere eine von einem permanent erregten, drehfeldbetriebenen Synchronmotor angetriebene Pumpe, zuverlässig zu ermitteln ist.The object of the invention is therefore to provide a method or a pump by means of which the flow rate of a fluid through a pump, in particular a driven by a permanently excited, synchronized motor synchronous motor driven pump, is reliably determined.

Diese Aufgabe wird gemäß der vorliegenden Erfindung dadurch gelöst, dass im Pumpbetrieb der Motor, insbesondere der permanent erregte, drehfeldbetriebene Synchronmotor, vom elektrischen/elektronischen Antrieb zumindest zeitweise, insbesondere periodisch, abgeschaltet wird. Im abgeschalteten Zustand kann sodann die in dem Pumpenmotor, insbesondere in dem Synchronmotor induzierte Spannung erfasst und aus der erfassten induzierten Spannung die Durchflussmenge des Fluids ermittelt werden.This object is achieved according to the present invention in that in the pumping operation of the motor, in particular the permanently excited, rotating field-driven synchronous motor, at least temporarily, in particular periodically, is switched off by the electric / electronic drive. In the switched-off state, the voltage induced in the pump motor, in particular in the synchronous motor, can then be detected and the flow rate of the fluid can be determined from the detected induced voltage.

Das erfindungsgemäße Verfahren bzw. die erfindungsgemäße Pumpe macht sich die Überlegung zunutze, dass ein Motor nicht nur durch elektrischen Antrieb als Motor sondern auch umgekehrt als Generator eingesetzt werden kann. Dies gilt insbesondere für permanent erregte drehfeldbetriebene Synchronmotoren. Bei Motoren kann bei Drehung des Läufers von aussen an den Statoranschlüssen eine Induktionsspannung abgegriffen werden, die durch die Drehung des Läufers hervorgerufen wird. Dies gilt insbesondere für permanent erregte drehfeldbetriebene Synchronmotoren.The inventive method or the pump of the invention makes use of the consideration that a motor can be used not only by electric drive as a motor but also vice versa as a generator. This applies in particular to permanent-magnet field-wound synchronous motors. In motors, upon rotation of the rotor from the outside at the stator terminals an induction voltage can be tapped, which is caused by the rotation of the rotor. This applies in particular to permanent-magnet field-wound synchronous motors.

Der Erfindung liegt weiterhin die Überlegung zu Grunde, dass unterschiedliche Durchflussmengen in einer durch einen Motor angetriebenen Pumpe einen Einfluss auf den zeitlichen Verlauf der generatorischen induzierten Spannung haben.The invention is further based on the consideration that different flow rates in a pump driven by a motor have an influence on the time course of the generator-induced voltage.

Bei dem erfindungsgemäßen Verfahren wird dementsprechend der Motor, z. B. der permanent erregte Synchronmotor, welcher durch einen Frequenzumrichter geregelt angetrieben werden kann, von der antreibenden Elektronik zumindest für ein vorbestimmtes Zeitintervall abgeschaltet, so dass dann bevorzugt aus dem zeitlichen Verlauf der erfassten induzierten Spannung die Durchflussmenge ermittelt werden kann. Die Ermittlung kann z.B. durch Vergleich mit Referenzkennlinien, -kennfeldern, oder -kennwerten erfolgen.In the method according to the invention, accordingly, the engine, for. B. the permanent magnet synchronous motor, which can be driven by a frequency controlled regulated off by the driving electronics at least for a predetermined time interval, so that then preferably from the time course of the detected induced voltage, the flow rate can be determined. The determination may e.g. by comparison with reference characteristic curves, characteristic maps, or characteristic values.

Die induzierte, insbesondere an den Statoranschlüssen abfallende Spannung kann beispielsweise durch einen Analog-Digital-Wandler aufgenommen werden. Dieser kann z.B. bei einem permanent erregten Synchronmotor in einem Mikrocontroller untergebracht sein, welcher vorzugsweise auch die Ansteuerung des Wechselrichters im Frequenzumrichter zum Antrieb übernimmt.The induced, in particular at the stator terminals sloping voltage can be recorded, for example, by an analog-to-digital converter. This can e.g. be housed in a permanently excited synchronous motor in a microcontroller, which preferably also takes over the control of the inverter in the frequency converter for driving.

Nach dem Abschalten des Motors, z.B. bei einem Synchronmotor von dem antreibenden Drehfeld, kommt der Motor je nach aktueller Durchflussmenge langsamer oder schneller zum Stillstand, wenn nicht bereits vor Erreichen des Stillstandes der Motor wieder angeschaltet würde.After switching off the engine, e.g. in a synchronous motor of the driving rotating field, the engine comes slower or faster depending on the current flow rate to a halt, if not already before reaching the standstill of the engine would be turned on again.

Dem entsprechend ist der zeitliche Verlauf der aufgenommenen, beispielsweise in einem Zwischenspeicher niedergelegten induzierten Spannung charakteristisch für die Durchflussmenge, insbesondere im Zeitpunkt der Abschaltung.Accordingly, the time profile of the recorded, for example, stored in a buffer memory induced voltage is characteristic of the flow rate, especially at the time of shutdown.

So besteht die Möglichkeit, nach der Erfassung und gegebenenfalls Zwischenspeicherung des zeitlichen Verlaufs der induzierten Spannung - gegebenenfalls bis der Motor zum Stillstand kommt - zum Beispiel aus der Abnahme der induzierten Spannung die Durchflussmenge zu ermitteln. Die Abnahme der induzierten Spannung kann hierbei besonders vorteilhaft durch den zeitlichen Verlauf der Hüllkurve der erfassten induzierten Spannung ermittelt werden.Thus, it is possible to determine the flow rate, for example, from the decrease in the induced voltage after the detection and, if appropriate, intermediate storage of the time profile of the induced voltage, if appropriate until the motor comes to a standstill. The decrease in the induced voltage can be determined particularly advantageously by the time profile of the envelope of the detected induced voltage.

Ebenso besteht alternativ oder in Kombination mit dem vorher Genannten die Möglichkeit, aus dem zeitlichen Verlauf der induzierten Spannung deren Phasenlage und hieraus die Durchflussmenge zu ermitteln. Hierbei kann zur Bestimmung der Phasenlage die erfasste Spannung bzw. der erfasste zeitliche Spannungsverlauf z.B. mit einer Referenzkurve, d.h. einer als Referenz abgelegten Spannungskennlinie ermittelt werden. Eine solche Referenzkennlinie oder gegebenenfalls auch ein Referenzkennfeld kann z.B. in einem Speicher der Motorelektronik für einen solchen Vergleich vorgehalten werden.Likewise, alternatively or in combination with the previously mentioned, it is possible to determine the phase position and hence the flow rate from the time profile of the induced voltage. In this case, the detected voltage or the detected temporal voltage curve can be used to determine the phase position, for example. with a reference curve, i. be determined as a reference stored voltage characteristic. Such a reference characteristic or, if appropriate, also a reference characteristic can e.g. be kept in a memory of the engine electronics for such a comparison.

Da der Motor, wie bereits erwähnt, je nach Durchflussmenge langsamer oder schneller zum Stillstand kommt, ist alternativ oder in Kombination auch die Abnahme der Frequenz der induzierten Generatorspannung ein Maß für die Durchflussmenge. Es besteht daher gemäß der Erfindung die Möglichkeit, aus dem aufgenommenen induzierten Spannungsverlauf den zeitlichen Abstand der einzelnen Spannungspeaks, mithin also die Frequenz zu ermitteln und insbesondere aus der Änderung der Frequenz z.B. zwischen aufeinanderfolgenden Spannungspeak-Paaren die Durchflussmenge zu ermitteln.Since, as already mentioned, the motor comes to a standstill more slowly or more quickly, depending on the flow rate, alternatively or in combination, the decrease in the frequency of the induced generator voltage is also a measure of the flow rate. Therefore, according to the invention, it is possible to determine from the recorded induced voltage curve the time interval of the individual voltage peaks, that is to say the frequency, and in particular from the change of the frequency, for example. to determine the flow rate between successive pairs of stress peaks.

Bei allen Ausführungen besteht die Möglichkeit, den zeitlichen Verlauf der induzierten Spannung mit einer Referenz wie vorgenannt zu vergleichen oder beispielsweise bei Messung der Frequenzwerte bzw. Frequenzänderungen diese mit gespeicherten Werten zu vergleichen, um aus diesem Vergleich auf die Durchflussmenge zu schließen.In all versions, it is possible to compare the time profile of the induced voltage with a reference as mentioned above or, for example, when measuring the frequency values or frequency changes, to compare these with stored values in order to deduce the flow rate from this comparison.

Eine Pumpe, mit der ein solches Verfahren durchgeführt werden kann, enthält dem entsprechend bevorzugter Weise eine Schaltung, mittels derer die erfasste induzierte Spannung, insbesondere der zeitliche Spannungsverlauf und/oder hieraus abgeleite Werte mit einer abgespeicherten Referenzkennlinie, einem Referenzkennfeld oder Referenzwerten vergleichbar ist.A pump, with which such a method can be carried out, accordingly contains a circuit by means of which the detected induced voltage, in particular the temporal voltage curve and / or values derived therefrom, are comparable to a stored reference characteristic, a reference characteristic field or reference values.

Zur Ermittlung der Durchflussmenge kann es vorgesehen sein, den Motor mit einer geeigneten Motorreglung zu einem bestimmten Zeitpunkt auszuschalten und den zeitlichen Verlauf der dann induzierten Generatorspannung bis zum Stillstand des Motors messtechnisch zu erfassen und gegebenenfalls zu speichern.To determine the flow rate, it may be provided to switch off the motor with a suitable motor control at a specific time and to record the time course of the generator voltage then induced until the motor is at standstill and optionally store it.

Es besteht jedoch nicht die Notwendigkeit, den Motor bis zum Stillstand auslaufen zu lassen, so dass es bevorzugt vorgesehen ist, den Motor während des Pumpbetriebes nur über ein kurzes zeitliches Intervall auszuschalten, innerhalb dieses zeitlichen Intervalls die Messung und gegebenenfalls Speicherung der induzierten Spannung vorzunehmen und anschließend den Motor wieder definiert, z.B. an das Drehfeld, anzuschalten, um die Pumpe weiter zu betreiben.However, there is no need to allow the engine to coast to a standstill, so that it is preferably provided to turn off the engine during the pumping operation only over a short time interval to make within this time interval, the measurement and optionally storage of the induced voltage and then redefined the motor, eg to the rotating field to turn on to continue to operate the pump.

Ein solches zeitliches Messintervall kann derart kurz gehalten werden, dass eine ausreichend sichere Ermittlung der Durchflussmenge möglich ist, ohne dass die Pumpe signifikant an Drehzahl verliert. So kann es beispielsweise ausreichend sein, dass die Pumpe nur über einen Zeitraum von wenigen induzierten Spannungspeaks, beispielsweise 2 bis 10 Spannungspeaks, ausgeschaltet ist.Such a temporal measuring interval can be kept so short that a sufficiently reliable determination of the flow rate is possible without the pump losing significant speed. For example, it may be sufficient that the pump is switched off only over a period of a few induced voltage peaks, for example 2 to 10 voltage peaks.

Bei dem Wiedereinschalten der Pumpe nach Ablauf des vorgegebenen zeitlichen Intervalls ist es bei Synchronmotoren bevorzugt vorgesehen, dass das durch den Frequenzumrichter an den Synchronmotor neu anzulegende Drehfeld zunächst an den Motor synchronisiert wird, da dieser durch den bremsenden Effekt des Fluids dem ursprünglichen antreibenden Drehfeld nacheilt.When the pump is switched back on after the predetermined time interval, it is preferably provided in synchronous motors that the rotary field to be newly applied by the frequency converter to the synchronous motor is first synchronized to the motor, since it lags the original driving rotary field due to the braking effect of the fluid.

Um eine solche Synchronisation zu erreichen, ist es bevorzugt vorgesehen, dass das benötigte neue Drehfeld zur Anschaltung an den Synchronmotor aus der zuvor erfassten induzierten Spannung, insbesondere aus dem zeitlichen Spannungsverlauf ermittelt wird. So kann beispielsweise aus dem zeitlichen Verlauf der erfassten induzierten Spannung auf die benötigte Frequenz- und Phasenlage des anzuschaltenden Drehfeldes geschlossen werden.In order to achieve such a synchronization, it is preferably provided that the required new rotary field for connection to the synchronous motor is determined from the previously detected induced voltage, in particular from the temporal voltage curve. For example, from the temporal Course of the detected induced voltage to the required frequency and phase of the rotating field to be closed.

Mit dem erfindungsgemäßen Verfahren und einer Pumpe, welche insbesondere eine elektrische Schaltung zur Durchführung des erfindungsgemäßen Verfahrens umfasst, besteht dem entsprechend die Möglichkeit, eine Druck- bzw. Volumenregelung des Pumpenkreislaufes durchzuführen, selbst in Bereichen, in denen die Kennlinie der elektrischen Leistung oder Durchflussmenge eine sehr flache Steigung oder ein Plateau aufweist.With the method according to the invention and a pump, which in particular comprises an electrical circuit for carrying out the method according to the invention, there is accordingly the possibility to perform a pressure or volume control of the pump circuit, even in areas where the characteristic of the electrical power or flow rate has a very flat slope or a plateau.

Ein Ausführungsbeispiel der Erfindung ist in den nachfolgenden Figuren dargestellt. Es zeigen:

Figur 1:
den zeitlichen Verlauf zweier verschiedener Messkurven der induzierten Spannung bei zwei unterschiedlichen Durchflussmengen;
Figur 2:
die zeitliche Abnahme der induzierten Spannung für drei verschiedene Durchflussmengen in einer zeitlich höher aufgelösten Darstellung.
An embodiment of the invention is shown in the following figures. Show it:
FIG. 1:
the time course of two different measured curves of the induced voltage at two different flow rates;
FIG. 2:
the temporal decrease of the induced voltage for three different flow rates in a higher temporal resolution.

Figur 1 zeigt den typischen zeitlichen Verlauf von induzierten Spannungen, die nach Abschaltung des treibenden Drehfeldes an einem z.B. permanent erregten Synchronmotor abgegriffen werden kann. Es sind hier zwei Messkurven 1 und 2 dargestellt, wobei erkennbar ist, dass der zeitliche Verlauf der beiden Messkurven, die bei unterschiedlichen Durchflussmengen aufgenommen wurden, von einander abweichen. FIG. 1 shows the typical time course of induced voltages that can be tapped after switching off the driving rotary field on a permanent magnet synchronous motor, for example. Two measurement curves 1 and 2 are shown here, whereby it can be seen that the time course of the two measurement curves, which were recorded at different flow rates, differ from one another.

Deutlicher erkennbar ist der Unterschied zwischen den Messkurven zu verschiedenen Durchflussmengen in der Figur 2, die eine zeitlich höher aufgelöste Darstellung von drei Messkurven 1,2 und 3 für drei verschiedene Durchflussmengen von 10 m3/h, 10,5 m3/h und 11 m3/h zeigt.Clearly recognizable is the difference between the measuring curves to different flow rates in the FIG. 2 that is a higher in time resolved representation of three curves 1,2 and 3 for three different flow rates of 10 m 3 / h, 10.5 m 3 / h and 11 m 3 / h shows.

Aus den aufgenommenen Messkurven lässt sich z.B. die unterschiedliche Phasenlage gegenüber einer Referenzkennlinie bzw. im vorliegenden Bild hier z.B. der zweiten Messkurve 2 gegenüber der ersten Messkurve 1 ermitteln.From the recorded measuring curves can be, for example the different phase position relative to a reference characteristic or in the present image here e.g. of the second measurement curve 2 relative to the first measurement curve 1.

Ebenfalls charakteristisch ist die zeitliche Abnahme der induzierten Spannungen, bzw. die Abnahme der Höhe der Spannungspeaks, wie sie anhand der Hüllkurve 3 in der Figur 1 dargestellt ist.Also characteristic is the temporal decrease of the induced voltages, or the decrease in the height of the voltage peaks, as determined by the envelope 3 in FIG FIG. 1 is shown.

Auch solche Hüllkurven zeigen einen charakteristischen, für verschiedene Durchflussmengen gegebenen Verlauf. Es lässt sich dem entsprechend auch aus den Hüllkurven der Spannungen auf die Durchflussmenge zurückschließen, beispielsweise durch Vergleich der aufgenommenen Spannungen untereinander oder durch Vergleich mit einer beispielsweise gespeicherten Referenzkennlinie bzw. einem Referenzkennfeld.Even such envelopes show a characteristic course given for different flow rates. Accordingly, it is also possible to deduce the flow rate from the envelopes of the voltages, for example by comparing the recorded voltages with one another or by comparison with a reference characteristic curve or a reference characteristic field stored, for example.

Die Figur 1 zeigt weiterhin die Möglichkeit, auch aus der Frequenzänderung der aufgenommenen Spannungskurve auf eine Durchflussmenge zurückzuschließen. So ist in der Figur 1 exemplarisch z.B. für die Spannungskurve 1 dargestellt, dass zwischen einem ersten Spannungspeak-Paar zunächst eine Zeit Δt1 ermittelt werden kann, wobei zwischen einem folgenden Spannungspeak-Paar eine Zeit Δt2 gemessen wird. Aus der Änderung der Zeit zwischen den beiden Messwerten Δt1 und Δt2, die auch gleichzeitig die Frequenzänderung darstellt, lässt sich ebenfalls rückschließen auf die Durchflussmenge, beispielsweise durch Vergleich mit Referenzwerten, die ebenfalls in einem Speicher abgelegt sein können.The FIG. 1 also shows the possibility of also infer from the change in frequency of the recorded voltage curve to a flow rate. So is in the FIG. 1 shown as an example for the voltage curve 1 that between a first pair of voltage peaks first a time .DELTA.t 1 can be determined, wherein between a following pair of voltage peaks, a time .DELTA.t 2 is measured. The change in the time between the two measured values Δt 1 and Δt 2 , which also simultaneously represents the frequency change, can also be deduced from the flow rate, for example by comparison with reference values, which can likewise be stored in a memory.

Die hier im konkreten Fall dargelegten Möglichkeiten, die Durchflussmengen aus den erfassten induzierten Spannungen zu ermitteln, sind als nicht abschließend zu betrachten. Es können noch andere Charakteristika, die sich aus den zeitlichen Verläufen der induzierten Spannungen direkt oder indirekt ermitteln lassen, herangezogen werden, um hieraus die Durchflussmengen unmittelbar, durch Vergleich mit anderen Messwerten oder durch Vergleich mit gespeicherten Referenzwerten oder -kennlinien bzw. -kennfeldern zu ermitteln.The possibilities presented here in this case of determining the flow rates from the recorded induced voltages are not exhaustive. There may be other characteristics, arising from the time courses of the induced voltages directly or indirectly be determined in order to determine the flow rates directly from this, by comparison with other measured values or by comparison with stored reference values or characteristic curves or characteristic maps.

Mit dem dargelegten Verfahren bzw. einer Pumpe zur Durchführung des Verfahrens kann dem entsprechend ohne Bereitstellung einer weiteren Messvorrichtung auf die aktuell vorliegende Durchflussmenge eines Fluids, z.B. Wasser durch die Pumpe geschlossen werden. Das Verfahren bzw. eine solche Pumpe ist dem entsprechend sehr kostengünstig und wirtschaftlich, da im Wesentlichen das erfindungsgemäße Verfahren durch eine Software in der Motorsteuerung, also beispielsweise im Mikrocontroller des Frequenzumrichters eines Synchronmotors realisiert werden kann.Accordingly, with the method and / or a pump for carrying out the method, without providing a further measuring device, it is possible to determine the current flow rate of a fluid, e.g. Water to be closed by the pump. The method or such a pump is accordingly very cost-effective and economical, since essentially the method according to the invention can be implemented by software in the motor control, that is, for example, in the microcontroller of the frequency converter of a synchronous motor.

Claims (11)

  1. Method of determining the flow rate of a fluid through a pump, in particular through a pump driven by a permanent-field synchronous motor, characterised in that, during operation of the pump, the motor is switched off at least intermittently, in particular cyclically, by the electric/electronic drive, the voltage (1, 2, 3) induced in the motor is measured while it is switched off and the flow rate of the fluid is determined from the measured induced voltage (1, 2, 3).
  2. Method according to claim 1, characterised in that the flow rate is determined from the variation of the induced voltage (1, 2, 3) with time, in particular by comparing the variation of the induced voltage (1, 2, 3) with time and/or measured values determined therefrom with a reference curve, a reference characteristic or reference values.
  3. Method according to claim 2, characterised in that the flow rate is determined from the phase angle of the induced voltage (1, 2, 3).
  4. Method according to one of the preceding claims, characterised in that the flow rate is determined from the variation of the envelope of the measured induced voltage (1, 2, 3) with time.
  5. Method according to one of the preceding claims, characterised in that the flow rate is determined from the frequency of the measured induced voltage (1, 2, 3) or from the variation of the frequency thereof with time.
  6. Method according to one of the preceding claims, characterised in that, once the motor has been switched off and the induced voltage (1, 2, 3) measured over a predetermined period of time, the motor is switched on again.
  7. Method according to claim 6, characterised in that, before a rotating field is applied to a synchronous motor, the rotating field is synchronised with the motor.
  8. Method according to claim 7, characterised in that the rotating field required for the synchronisation is determined from the previously measured induced voltage (1,2,3).
  9. Pump for delivering fluid, comprising a motor, in particular a permanent-field synchronous motor, and an electronic/electric system for open-loop and/or closed-loop control of the motor, characterised in that it comprises an electronic circuit for carrying out a method according to one of the preceding claims.
  10. Pump according to claim 9, characterised in that it comprises a memory with at least one stored reference curve and/or with a reference characteristic and/or reference values.
  11. Pump according to claim 10, characterised in that a measured induced voltage (1, 2, 3), in particular the variation of the voltage with time and/or values determined therefrom, can be compared with a reference curve and/or a reference characteristic and/or reference values by means of the circuit.
EP20030009647 2002-07-29 2003-04-30 Method for determining the flow rate in a pump Expired - Fee Related EP1387087B1 (en)

Applications Claiming Priority (2)

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DE10234630 2002-07-29
DE2002134630 DE10234630A1 (en) 2002-07-29 2002-07-29 Method for determining the flow rate of a fluid through a pump

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EP1387087A3 EP1387087A3 (en) 2009-10-28
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EP2743509B1 (en) * 2012-12-11 2015-07-01 Pierburg GmbH Feed pump dry run detection
US8909425B2 (en) * 2013-04-12 2014-12-09 GM Global Technology Operations LLC Speed-based flow device diagnostic system and method
US10859592B2 (en) * 2017-01-31 2020-12-08 Tecan Trading Ag Method of aspirating by pipetting and pipetting apparatus
CN113915145B (en) * 2021-09-24 2023-07-28 北京亿华通科技股份有限公司 Overpressure monitoring control method for fuel cell cooling system

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DE50313576D1 (en) 2011-05-12
EP1387087A3 (en) 2009-10-28
EP1387087A2 (en) 2004-02-04
DE10234630A1 (en) 2004-04-08

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