WO2021058723A1 - Method for determining the position of an armature of an electromagnetic linear actuator - Google Patents

Method for determining the position of an armature of an electromagnetic linear actuator Download PDF

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Publication number
WO2021058723A1
WO2021058723A1 PCT/EP2020/076865 EP2020076865W WO2021058723A1 WO 2021058723 A1 WO2021058723 A1 WO 2021058723A1 EP 2020076865 W EP2020076865 W EP 2020076865W WO 2021058723 A1 WO2021058723 A1 WO 2021058723A1
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Prior art keywords
current
armature
pulse width
modulation signal
width modulation
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PCT/EP2020/076865
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German (de)
French (fr)
Inventor
Erik HECHTL
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Magna powertrain gmbh & co kg
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Publication of WO2021058723A1 publication Critical patent/WO2021058723A1/en

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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D5/00—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable
    • G01D5/12—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means
    • G01D5/14—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage
    • G01D5/20—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature
    • G01D5/2006—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils
    • G01D5/2013—Mechanical means for transferring the output of a sensing member; Means for converting the output of a sensing member to another variable where the form or nature of the sensing member does not constrain the means for converting; Transducers not specially adapted for a specific variable using electric or magnetic means influencing the magnitude of a current or voltage by varying inductance, e.g. by a movable armature by influencing the self-induction of one or more coils by a movable ferromagnetic element, e.g. a core
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/18—Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
    • H01F7/1844—Monitoring or fail-safe circuits
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/18—Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
    • H01F7/1844—Monitoring or fail-safe circuits
    • H01F2007/185—Monitoring or fail-safe circuits with armature position measurement
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/08—Electromagnets; Actuators including electromagnets with armatures
    • H01F7/18—Circuit arrangements for obtaining desired operating characteristics, e.g. for slow operation, for sequential energisation of windings, for high-speed energisation of windings
    • H01F7/1844—Monitoring or fail-safe circuits
    • H01F2007/1861—Monitoring or fail-safe circuits using derivative of measured variable

Definitions

  • the present invention relates to a method for determining the posi tion of an armature of an electromagnetic linear actuator.
  • Electromagnetic linear actuators are used, for example, in motor vehicles, especially as inductive solenoids or actuators in separating clutches, for shutting down parts of a drive train, or in parking locks.
  • Such actuators use an armature that is linearly moveable in a current-flowing coil and can be moved to a specific position by applying a current to the coil and the electromagnetic force caused by this, often in conjunction with a counteracting force such as a spring force.
  • actuators of this type have to provide feedback that is as accurate as possible about the current position of the linearly movable armature to a control unit.
  • an armature of such a linear actuator of a form-fitting coupling can be important in order to achieve a safety goal, for example that a specified spin speed of a coupling must be undercut.
  • a displacement sensor is usually used to determine the position of an armature of an electromagnetic linear actuator.
  • a method for determining the armature position in an electromagnet is also known from DE 10 2007 016 787 A1, the magnetic flux distribution dependent on the armature position being used to determine the position.
  • the object is achieved by a method for determining the position of an armature of an electromagnetic linear actuator, the armature being linearly movable in a coil of the linear actuator, the coil for moving the armature being controlled with an electrical pulse-width modulation signal, two of which Current measured values are measured during a period of the pulse width modulation signal, a current change value being determined from the two current measured values, an assignment of current change values to armature positions being stored in a characteristic map, and the current position of the armature to the current change value being determined by means of this characteristic field .
  • the position of the armature of the linear actuator is determined by measuring two current values. There is therefore no additional distance sensor required. Two current measurements are measured during one period of a pulse width modulation signal. The change in the measured current values, preferably on a negative edge of the pulse width modulation signal, is dependent on the position of the armature in the linear actuator or in its coil.
  • a previously defined and stored map in particular a 2D map, is used that holds current change values for armature positions, preferably for different voltages or pulse widths of the pulse width modulation signal. This method for determining the position of an armature is also suitable for varying pulse widths and thus for current-controlled linear actuators.
  • the current change value preferably relates to the falling edge of the pulse width modulation signal.
  • the two current measured values thus indicate a measure for the drop in the current value during a period.
  • the two current measured values that are measured during a period of the pulse width modulation signal are preferably a current maximum and a current minimum.
  • the position of the armature can be determined during a linear motion of the armature, that is to say dynamically.
  • the determination can also take place with a stationary anchor, i.e. statically.
  • An assignment of static, averaged current change values to armature positions is preferably stored in the characteristic diagram, i.e. current change values values that were determined and averaged over several signal periods according to a transient behavior of the current intensity.
  • An assignment of current change values to armature positions for different voltages or different pulse widths is particularly preferably stored in the characteristic map.
  • the electrical pulse width modulation signal for controlling the coil is preferably current-regulated, so that the pulse width of the pulse width modulation signal, that is to say the voltage, varies from period to period.
  • the pulse width modulation signal can, however, also be voltage-regulated, which simplifies the determination of the position of the armature due to the constant pulse width.
  • a mean current pulse width can be determined as the mean value over several periods of the pulse width modulation signal and the current position of the armature for the current change value for this mean current pulse width can be determined using the characteristic field.
  • FIG. 1 is a diagram of a time-dependent current signal for four actuation processes with different restricted armature end positions for a method according to the invention.
  • FIG. 2 is a detailed illustration which shows a section of FIG. 1 in a stationary state.
  • Fig. 3 shows a table for measured values that are required for position determination.
  • FIG. 4 is a diagram that shows current change values of the falling edges as a function of the armature position for different (constant) demand voltages and thus a characteristic diagram for a method according to the invention.
  • Fig. 5 is a diagram that shows a comparison between ge measured time-dependent position and according to the invention, certain position of the armature in three actuation processes with different restricted end positions.
  • a method for determining the position of an armature of an electromagnetic linear actuator is specified, the armature being linearly movable in a coil of the linear actuator, the coil for moving the armature being controlled with an electrical pulse width modulation signal, with two current measured values Imax, imine currency rend a period of the pulse width modulation signal to be measured, from the two measured current values I m ax, imine and their time stamps tmax, tmin, a current change value DI / at is determined, wherein in a map, a mapping of current change values AI / at to Ankerposi- functions x is stored, and the current position of the armature for the current change value DI / At is determined by means of this map.
  • Wl 3.88 mm to 0.00 mm
  • W2 3.88 mm to 0.88 mm
  • W3 3.88 mm to 2.13 mm
  • W4 3.88 mm to 3.88 mm .
  • the demand voltage U is 5 V. Due to changes in the differential inductance, the current rate of increase of the current depends, as can be clearly seen in FIG. 2, on the position of the armature x or the armature end position Wl, ..., W4 from.
  • Fig. 4 shows the rate of increase in current AI / At of the falling edges of the current signal as a function of the position of the armature x, for different (constant) requirement voltages Ul, U2, U3 and U4.
  • Ul constant requirement voltage
  • the solid lines each show static measurements, i.e. current change values AI / At averaged over several periods according to the transient behavior.
  • the dashed lines show dynamic measurements. Measurements were made at room temperature in each case.
  • the curves shown, preferably the static measurements, that is to say the solid lines, are stored in a characteristic map for use by a control unit in a method according to the invention.
  • Fig. 5 finally shows a comparison between measured time-dependent positions of the armature (solid lines) and positions (circles) determined by the method according to the invention, the current rate of change being used to determine the position, with three actuation processes with different end positions E 1, E2 and E3.
  • the starting point for determining the position according to the invention is the characteristics map according to FIG. 4, which is stored in a memory as a look-up table (LUT).
  • LUT look-up table
  • FIG. 3 shows a table of the measured values that are required for determining the position.
  • the current change rate AI / At is determined from these measured values at each point in time, to which a position is assigned with the aid of the family of characteristics (FIG. 4).
  • AI / At (Imin - Imax) / (tmin - t max ) shown below in FIG Current change value AI / At.
  • the position x of the armature can then be determined by interpolation into the characteristic curve in FIG. 4.
  • the LUT Since the estimated position is expected to fluctuate around the real position, the LUT is extrapolated to a position range x e (-2.6) mm.
  • the current range must also be expanded to I e (0.7) A, since reaching the limit of the LUT due to current fluctuations must be avoided.
  • the data from the LUT can be used immediately.
  • the pulse width must first be evaluated as a function of time and converted into a corresponding mean demand voltage before the interpolation can be performed.
  • the measured pulse width usually fluctuates strongly (standard deviation 0.1 ms). Therefore, before using the LUT, the mean value must be evaluated over 2 to 15 periods in order to reduce the standard deviation of the calculated position.
  • a holding current of 2.5 A is usually set after an actuation process in order to prevent the armature or piston or tappet from being pulled back into its starting position by the spring. The analysis of this holding current using the rate of rise method does not provide any information about the armature position.
  • the temperature dependency of the rate of change of current DI / At can also be taken into account in a method according to the invention, for example in an extended LUT.
  • a largely linear dependence of the current rate of change AI / At on the temperature was found, with measurements in the range of 20 - 60 ° C.
  • the method proposed here can therefore be improved by a simple temperature compensation, in particular by taking into account a temperature-dependent linear factor, at different ambient temperatures.
  • the use of the static data (solid lines) in the LUT (Fig. 4) instead of the dynamic (dashed lines) leads to only minor differences in the results for the position determination at low demand voltages U. Le- only the data points for the end position 0 mm, i.e.

Abstract

The invention relates to a method for determining the position (x) of an armature of an electromagnetic linear actuator, wherein: the armature can be moved linearly in a coil of the linear actuator; the coil is controlled with an electrical pulse-width modulation signal in order to move the armature; two current measurement values (Imax, Imin) are measured during a period of the pulse-width modulation signal; a current change value (ΔI/Δt) is determined from the two current measurement values (Imax, Imin); in a characteristic map, an assignment of current change values (ΔI/Δt) to armature positions (x) is stored; and the present position (x) of the armature is determined on the basis of the current change value (ΔI / Δt) by means of said characteristic map.

Description

Verfahren zur Bestimmung der Position eines Ankers eines elektromagnetischen Linearaktuators Method for determining the position of an armature of an electromagnetic linear actuator
Gebiet der Erfindung Field of the invention
Die vorliegende Erfindung betrifft ein Verfahren zur Bestimmung der Posi tion eines Ankers eines elektromagnetischen Linearaktuators. The present invention relates to a method for determining the posi tion of an armature of an electromagnetic linear actuator.
Stand der Technik State of the art
Elektromagnetische Linearaktuatoren werden beispielsweise in Kraftfahr zeugen benutzt, insbesondere als induktive Schaltmagnete bzw. Aktua toren in Trennkupplungen, zur Stilllegung von Teilen eines Antriebsstran ges, oder in Parksperren. Electromagnetic linear actuators are used, for example, in motor vehicles, especially as inductive solenoids or actuators in separating clutches, for shutting down parts of a drive train, or in parking locks.
Solche Aktuatoren verwenden einen Anker, der in einer stromdurchflosse nen Spule linear beweglich gelagert ist und durch Anlegen eines Stromes an die Spule und hierdurch verursachte elektromagnetische Kraft, oft im Zusammenspiel mit einer gegenwirkenden Kraft wie einer Federkraft, an eine bestimmte Position bewegt werden kann. Such actuators use an armature that is linearly moveable in a current-flowing coil and can be moved to a specific position by applying a current to the coil and the electromagnetic force caused by this, often in conjunction with a counteracting force such as a spring force.
Derartige Aktuatoren müssen in verschiedenen Anwendungen möglichst genaue Rückmeldungen über die aktuelle Position des linear beweglichen Ankers an eine Steuereinheit liefern. In various applications, actuators of this type have to provide feedback that is as accurate as possible about the current position of the linearly movable armature to a control unit.
Beispielsweise kann die genaue Position eines Ankers eines solchen Linea raktuators einer formschlüssigen Kupplung wichtig sein, um ein Sicher heitsziel, beispielsweise dass eine festgelegte Schleuderdrehzahl einer Kupplung unterschritten sein muss, zu erreichen. Zur Bestimmung der Position eines Ankers eines elektromagnetischen Linearaktuators wird üblicherweise ein Wegsensor verwendet. For example, the exact position of an armature of such a linear actuator of a form-fitting coupling can be important in order to achieve a safety goal, for example that a specified spin speed of a coupling must be undercut. A displacement sensor is usually used to determine the position of an armature of an electromagnetic linear actuator.
Aus der DE 10 2007 016 787 Al ist auch ein Verfahren zur Bestimmung der Ankerlage in einem Elektromagneten bekannt, wobei die von der An kerposition abhängige Magnetflußverteilung für die Positionsbestimmung genutzt wird. A method for determining the armature position in an electromagnet is also known from DE 10 2007 016 787 A1, the magnetic flux distribution dependent on the armature position being used to determine the position.
Zusammenfassung der Erfindung Summary of the invention
Es ist eine Aufgabe der Erfindung, ein Verfahren zur Bestimmung der Position eines Ankers eines elektromagnetischen Linearaktuators anzuge ben, das ohne Wegsensor und somit kostengünstig herstellbar ist und dabei eine genaue Positionsermittlung ermöglicht, insbesondere auch bei stromgeregelten Linearaktuatoren. It is an object of the invention to provide a method for determining the position of an armature of an electromagnetic linear actuator, which can be manufactured without a displacement sensor and thus inexpensively and thereby enables an exact position determination, in particular also in the case of current-controlled linear actuators.
Die Lösung der Aufgabe erfolgt durch ein Verfahren zur Bestimmung der Position eines Ankers eines elektromagnetischen Linearaktuators, wobei der Anker linear in einer Spule des Linearaktuators beweglich ist, wobei die Spule zur Bewegung des Ankers mit einem elektrischen Pulsweiten- modulations-Signal angesteuert wird, wobei zwei Strommesswerte wäh rend einer Periode des Pulsweitenmodulations-Signals gemessen werden, wobei aus den zwei Strommesswerten ein Stromänderungswert bestimmt wird, wobei in einem Kennfeld eine Zuordnung von Stromänderungswer ten zu Ankerpositionen abgelegt ist, und dass mittels dieses Kennfelds die aktuelle Position des Ankers zum Stromänderungswert bestimmt wird. The object is achieved by a method for determining the position of an armature of an electromagnetic linear actuator, the armature being linearly movable in a coil of the linear actuator, the coil for moving the armature being controlled with an electrical pulse-width modulation signal, two of which Current measured values are measured during a period of the pulse width modulation signal, a current change value being determined from the two current measured values, an assignment of current change values to armature positions being stored in a characteristic map, and the current position of the armature to the current change value being determined by means of this characteristic field .
Erfindungsgemäß wird die Position des Ankers des Linearaktuators mit tels Messung von zwei Stromwerten bestimmt. Es wird daher kein zusätz- licher Wegsensor benötigt. Zwei Strommesswerte werden während einer Periode eines Pulsweitenmodulations-Signals gemessen. Die Änderung der Strommesswerte, bevorzugt an einer negativen Flanke des Pulsweitenmo dulations-Signals, ist abhängig von der Position des Ankers im Linearak tuator bzw. in dessen Spule. Zur Bestimmung der Position wird ein zuvor definiertes und abgespeichertes Kennfeld, insbesondere 2D-Kennfeld, verwendet, dass Stromänderungswerte zu Ankerpositionen, bevorzugt für verschiedene Spannungen bzw. Pulsweiten des Pulsweitenmodulations- Signals bereithält. Diese Methode zur Bestimmung der Position eines An kers ist auch für variierende Pulsweiten und somit für stromgeregelte Linearaktuatoren geeignet. According to the invention, the position of the armature of the linear actuator is determined by measuring two current values. There is therefore no additional distance sensor required. Two current measurements are measured during one period of a pulse width modulation signal. The change in the measured current values, preferably on a negative edge of the pulse width modulation signal, is dependent on the position of the armature in the linear actuator or in its coil. To determine the position, a previously defined and stored map, in particular a 2D map, is used that holds current change values for armature positions, preferably for different voltages or pulse widths of the pulse width modulation signal. This method for determining the position of an armature is also suitable for varying pulse widths and thus for current-controlled linear actuators.
Weiterbildungen der Erfindung sind in den abhängigen Ansprüchen, der Beschreibung sowie den beigefügten Zeichnungen angegeben. Further developments of the invention are given in the dependent claims, the description and the accompanying drawings.
Vorzugsweise bezieht sich der Stromänderungswert auf die fallende Flan ke des Pulsweitenmodulations-Signals. Die beiden Strommesswerte geben somit ein Maß für den Abfall des Stromwertes während einer Periode an. The current change value preferably relates to the falling edge of the pulse width modulation signal. The two current measured values thus indicate a measure for the drop in the current value during a period.
Bevorzugt sind die zwei Strommesswerte, die während einer Periode des Pulsweitenmodulations-Signals gemessen werden, ein Strommaximum und ein Stromminimum. The two current measured values that are measured during a period of the pulse width modulation signal are preferably a current maximum and a current minimum.
Die Bestimmung der Position des Ankers kann während einer Linearbewe gung des Ankers, also dynamisch, erfolgen. Die Bestimmung kann auch bei einem ruhenden Anker, also statisch, erfolgen. The position of the armature can be determined during a linear motion of the armature, that is to say dynamically. The determination can also take place with a stationary anchor, i.e. statically.
In dem Kennfeld ist bevorzugt eine Zuordnung von statischen, gemittelten Stromänderungswerten zu Ankerpositionen abgelegt, also von Stromände- rungswerten, die über mehrere Signal-Perioden, nach einem transienten Verhalten der Stromstärke, bestimmt und gemittelt wurden. An assignment of static, averaged current change values to armature positions is preferably stored in the characteristic diagram, i.e. current change values values that were determined and averaged over several signal periods according to a transient behavior of the current intensity.
Besonders bevorzugt ist in dem Kennfeld eine Zuordnung von Stromände rungswerten zu Ankerpositionen für verschiedene Spannungen oder ver schiedene Pulsweiten abgelegt. An assignment of current change values to armature positions for different voltages or different pulse widths is particularly preferably stored in the characteristic map.
Bevorzugt ist das elektrische Pulsweitenmodulations-Signal zur Ansteue rung der Spule stromgeregelt, so dass die Pulsweite des Pulsweitenmodu- lations-Signals, also die Spannung, von Periode zu Periode variiert. Das Pulsweitenmodulations-Signal kann jedoch auch spannungsgeregelt sein, was die Bestimmung der Position des Ankers aufgrund der konstanten Pulsweite vereinfacht. The electrical pulse width modulation signal for controlling the coil is preferably current-regulated, so that the pulse width of the pulse width modulation signal, that is to say the voltage, varies from period to period. The pulse width modulation signal can, however, also be voltage-regulated, which simplifies the determination of the position of the armature due to the constant pulse width.
Insbesondere bei einem stromgeregelten Signal kann eine mittlere aktuelle Pulsweite als Mittelwert über mehrere Perioden des Pulsweitenmodulati- ons-Signals bestimmt werden und mittels des Kennfelds die aktuelle Posi tion des Ankers zum Stromänderungswert für diese mittlere aktuelle Pulsweite bestimmt werden. In particular with a current-regulated signal, a mean current pulse width can be determined as the mean value over several periods of the pulse width modulation signal and the current position of the armature for the current change value for this mean current pulse width can be determined using the characteristic field.
Kurzbeschreibung der Zeichnungen Brief description of the drawings
Die Erfindung wird im Folgenden beispielhaft unter Bezugnahme auf die Zeichnungen beschrieben. The invention is described below by way of example with reference to the drawings.
Fig. 1 ist ein Diagramm eines zeitabhängigen Stromsignals für vier Betätigungsvorgänge mit unterschiedlichen eingeschränkten Ankerendlagen für ein erfindungsge mäßes Verfahren. Fig. 2 ist eine Detaildarstellung, welche einen Ausschnitt von Fig. 1 in einem stationären Zustand zeigt. Fig. 1 is a diagram of a time-dependent current signal for four actuation processes with different restricted armature end positions for a method according to the invention. FIG. 2 is a detailed illustration which shows a section of FIG. 1 in a stationary state.
Fig. 3 zeigt eine Tabelle für Messwerte, die für die Positions bestimmung benötigt werden. Fig. 3 shows a table for measured values that are required for position determination.
Fig. 4 ist ein Diagramm, dass Stromänderungswerte der fal lenden Flanken in Abhängigkeit von der Ankerposition für verschiedene (konstante) Anforderungsspannungen zeigt und somit ein Kennfeld für ein erfindungsgemä ßes Verfahren. 4 is a diagram that shows current change values of the falling edges as a function of the armature position for different (constant) demand voltages and thus a characteristic diagram for a method according to the invention.
Fig. 5 ist ein Diagramm, dass einen Vergleich zwischen ge messener zeitabhängiger Position und erfindungsge mäß bestimmter Position des Ankers bei drei Betäti gungsvorgängen mit unterschiedlichen eingeschränk ten Endpositionen zeigt. Fig. 5 is a diagram that shows a comparison between ge measured time-dependent position and according to the invention, certain position of the armature in three actuation processes with different restricted end positions.
Detaillierte Beschreibung der Erfindung Detailed description of the invention
Erfindungsgemäß wird ein Verfahren zur Bestimmung der Position eines Ankers eines elektromagnetischen Linearaktuators angegeben, wobei der Anker linear in einer Spule des Linearaktuators beweglich ist, wobei die Spule zur Bewegung des Ankers mit einem elektrischen Pulsweitenmodu- lations-Signal angesteuert wird, wobei zwei Strommesswerte Imax, Imin wäh rend einer Periode des Pulsweitenmodulations-Signals gemessen werden, wobei aus den zwei Strommesswerten Imax, Imin und deren Zeitstempeln tmax ,tmin ein Stromänderungswert DI/At bestimmt wird, wobei in einem Kennfeld eine Zuordnung von Stromänderungswerten AI / At zu Ankerposi- tionen x abgelegt ist, und wobei mittels dieses Kennfelds die aktuelle Posi tion des Ankers zum Stromänderungswert DI/At bestimmt wird. According to the invention, a method for determining the position of an armature of an electromagnetic linear actuator is specified, the armature being linearly movable in a coil of the linear actuator, the coil for moving the armature being controlled with an electrical pulse width modulation signal, with two current measured values Imax, imine currency rend a period of the pulse width modulation signal to be measured, from the two measured current values I m ax, imine and their time stamps tmax, tmin, a current change value DI / at is determined, wherein in a map, a mapping of current change values AI / at to Ankerposi- functions x is stored, and the current position of the armature for the current change value DI / At is determined by means of this map.
Fig. 1 zeigt ein zeitabhängiges Stromsignal I für vier Betätigungsvorgänge mit unterschiedlichen Ankerwegen Wl, W2, W3; W4 und Anker-Endlagen. Dabei ist Wl = 3,88 mm bis 0,00 mm, W2 = 3,88 mm bis 0,88 mm, W3 = 3,88 mm bis 2, 13 mm, und W4 = 3,88 mm bis 3,88 mm. 1 shows a time-dependent current signal I for four actuation processes with different armature paths W1, W2, W3; W4 and anchor end positions. Wl = 3.88 mm to 0.00 mm, W2 = 3.88 mm to 0.88 mm, W3 = 3.88 mm to 2.13 mm, and W4 = 3.88 mm to 3.88 mm .
In Fig. 1 links ist jeweils das transiente Verhalten nach dem Einschalten der Steuerungsspannung zu sehen, in der Fig. 1 rechts ist der stationäre Zustand des Stromsignals zu sehen, der für einen Ausschnitt t = 0, 117 bis 0, 1195 Sekunden im Detail in Fig. 2 dargestellt ist. Die Anforderungs spannung U beträgt dabei 5 V. Aufgrund von Änderungen der differentiel len Induktivität hängt die aktuelle Anstiegsrate des Stroms, wie in Fig. 2 gut ersichtlich, von der Position des Ankers x bzw. der Anker-Endlage Wl, ..., W4 ab. In Fig. 1, left, the transient behavior after switching on the control voltage can be seen, in Fig. 1, right, the steady state of the current signal can be seen, which for a section t = 0.117 to 0.1195 seconds in detail in Fig. 2 is shown. The demand voltage U is 5 V. Due to changes in the differential inductance, the current rate of increase of the current depends, as can be clearly seen in FIG. 2, on the position of the armature x or the armature end position Wl, ..., W4 from.
Fig. 4 zeigt die Stromanstiegsrate AI / At der fallenden Flanken des Strom signals in Abhängigkeit von der Position des Ankers x, für verschiedene (konstante) Anforderungsspannungen Ul, U2, U3 und U4. Dabei ist Ul =Fig. 4 shows the rate of increase in current AI / At of the falling edges of the current signal as a function of the position of the armature x, for different (constant) requirement voltages Ul, U2, U3 and U4. Where Ul =
5 Volt, U2 = 4 Volt, U3 = 3 Volt und U4 = 2 Volt. 5 volts, U2 = 4 volts, U3 = 3 volts and U4 = 2 volts.
Die durchgehenden Linien zeigen jeweils statische Messungen, also Stro mänderungswerte AI / At gemittelt über mehrere Perioden nach dem tran sienten Verhalten. Die gestrichelten Linien zeigen dynamische Messungen. Gemessen wurde jeweils bei Raumtemperatur. Die dargestellten Verläufe, bevorzugt die statischen Messungen, also die durchgezogenen Linien, werden in einem Kennfeld zur Benutzung durch ein Steuergerät in einem erfindungsgemäßen Verfahren gespeichert. Fig. 5 zeigt schließlich einen Vergleich zwischen gemessenen zeitabhängi gen Positionen des Ankers (durchgezogene Linien) und durch das erfin dungsgemäße Verfahren bestimmten Positionen (Kreise), wobei also die Stromänderungsrate zur Bestimmung der Position verwendet wurde, bei drei Betätigungsvorgängen mit unterschiedlichen Endpositionen E 1 , E2 und E3. Die verwendete Steuerspannung betrug jeweils U = 5 Volt. The solid lines each show static measurements, i.e. current change values AI / At averaged over several periods according to the transient behavior. The dashed lines show dynamic measurements. Measurements were made at room temperature in each case. The curves shown, preferably the static measurements, that is to say the solid lines, are stored in a characteristic map for use by a control unit in a method according to the invention. Fig. 5 finally shows a comparison between measured time-dependent positions of the armature (solid lines) and positions (circles) determined by the method according to the invention, the current rate of change being used to determine the position, with three actuation processes with different end positions E 1, E2 and E3. The control voltage used was U = 5 volts in each case.
Der Ausgangspunkt für die erfindungsgemäße Positionsbestimmung ist das Kennfeld entsprechend Fig. 4, das als Look-Up-Tabelle (LUT) in einem Speicher abgelegt ist. The starting point for determining the position according to the invention is the characteristics map according to FIG. 4, which is stored in a memory as a look-up table (LUT).
Fig. 3 zeigt eine Tabelle der Messwerte, die für die Positionsbestimmung benötigt werden. Aus diesen Messwerten wird zu jedem Zeitpunkt die Stromänderungsrate AI / At ermittelt, welcher mit Hilfe des Kennlinienfelds (Fig. 4) eine Position zugeordnet wird. Durch eine Tabelle der Strommess werte wie in Fig. 3 dargestellt und die Anwendung der in Fig. 3 unten dargestellten Formel AI/At = (Imin - Imax) / (tmin - tmax) wird die mittlere Stromanstiegsrate der fallenden Flanken berechnet, also der Stromände rungswert AI/At. Durch Interpolation in die Kennlinie der Fig. 4 kann dann die Position x des Ankers bestimmt werden. 3 shows a table of the measured values that are required for determining the position. The current change rate AI / At is determined from these measured values at each point in time, to which a position is assigned with the aid of the family of characteristics (FIG. 4). Using a table of the current measurement values as shown in FIG. 3 and using the formula AI / At = (Imin - Imax) / (tmin - t max ) shown below in FIG Current change value AI / At. The position x of the armature can then be determined by interpolation into the characteristic curve in FIG. 4.
Da zu erwarten ist, dass die geschätzte Position um die reale Position her um schwankt, wird die LUT auf einen Positionsbereich x e (-2,6) mm hochgerechnet. Auch der Strombereich muss erweitert werden zu I e (0,7) A, da das Erreichen der Grenze der LUT aufgrund von Stromschwankun gen vermieden werden muss. Since the estimated position is expected to fluctuate around the real position, the LUT is extrapolated to a position range x e (-2.6) mm. The current range must also be expanded to I e (0.7) A, since reaching the limit of the LUT due to current fluctuations must be avoided.
Im Falle einer Spannungsregelung (Pulsweite bleibt über die Zeit konstant) kann man unmittelbar die Daten der LUT verwenden. Bei einer Stromre gelung muss zunächst die Pulsweite als Funktion der Zeit ausgewertet und in eine entsprechende mittlere Anforderungsspannung umgewandelt werden, bevor die Interpolation durchgeführt werden kann. Bei Verwen dung einer Stromregelung schwankt die gemessene Pulsweite in der Regel stark (Standardabweichung 0, 1 ms). Daher muss vor dem Einsatz der LUT der Mittelwert über 2 bis 15 Perioden ausgewertet werden, um die Stan dardabweichung der berechneten Position zu reduzieren. In the case of voltage regulation (pulse width remains constant over time), the data from the LUT can be used immediately. With a current control, the pulse width must first be evaluated as a function of time and converted into a corresponding mean demand voltage before the interpolation can be performed. When using a current control, the measured pulse width usually fluctuates strongly (standard deviation 0.1 ms). Therefore, before using the LUT, the mean value must be evaluated over 2 to 15 periods in order to reduce the standard deviation of the calculated position.
Die Steigung der Linien in Fig. 4 ist bei hohen Spannungen (zum Beispiel U 1 = 5 Volt) größer. Daher liefert das Anstiegsratenverfahren bei der ver wendeten Messaufstellung (Unsicherheit der gemessenen Anstiegsrate ca. 10 %) nur für eine Positionsschätzung mit einer minimalen Anforderungs spannung U = 4 V gute Ergebnisse, abhängig vom zulässigen Fehler der Positionsschätzung. In der technischen Anwendung des Magnetaktuators wird nach einem Betätigungsvorgang in der Regel ein Haltestrom von 2,5 A eingestellt, um zu verhindern, dass der Anker bzw. Kolben bzw. Stößel durch die Feder in seine Ausgangsposition zurückgezogen wird. Die Ana lyse dieses Haltestroms mittels der Anstiegsratenmethode liefert keine Aussage über die Ankerposition. The slope of the lines in FIG. 4 is greater at high voltages (for example U 1 = 5 volts). Therefore, with the measurement setup used (uncertainty of the measured increase rate approx. 10%), the rise rate method only provides good results for a position estimate with a minimum requirement voltage U = 4 V, depending on the permissible error in the position estimate. In the technical application of the magnetic actuator, a holding current of 2.5 A is usually set after an actuation process in order to prevent the armature or piston or tappet from being pulled back into its starting position by the spring. The analysis of this holding current using the rate of rise method does not provide any information about the armature position.
Optional kann auch die Temperaturabhängigkeit der Stromänderungsrate DI/At in einem erfindungsgemäßen Verfahren, beispielsweise in einer er weiterten LUT, berücksichtigt werden. In Untersuchungen wurde eine weitgehend lineare Abhängigkeit der Stromänderungsrate AI / At von der Temperatur gefunden, bei Messungen im Bereich 20 - 60 °C. Das hier vorgeschlagene Verfahren kann daher durch eine einfache Temperatur kompensation, insbesondere durch Berücksichtigung eines temperatur abhängigen linearen Faktors, bei verschiedenen Umgebungstemperaturen verbessert werden. Wie in Fig. 5 ersichtlich, führt die Verwendung der statischen Daten (durchgezogene Linien) in der LUT (Fig. 4) anstelle der dynamischen (ge strichelte Linien) nur zu geringen Unterschieden in den Ergebnissen für die Positionsbestimmung bei niedrigen Anforderungsspannungen U. Le- diglich die Datenpunkte für die Endposition 0 mm, also bei E3, unter scheiden sich während der Ankerbewegung deutlich von der tatsächlichen Position x. Die Diskrepanz zwischen statischen und dynamischen Daten wird jedoch bei hohen Spannungen (und hohen Ankergeschwindigkeiten) größer. Für eine Anforderungsspannung U = 9 V wird erwartet, dass die Positionsbestimmung nur im statischen Fall gute Ergebnisse liefert. Optionally, the temperature dependency of the rate of change of current DI / At can also be taken into account in a method according to the invention, for example in an extended LUT. In investigations, a largely linear dependence of the current rate of change AI / At on the temperature was found, with measurements in the range of 20 - 60 ° C. The method proposed here can therefore be improved by a simple temperature compensation, in particular by taking into account a temperature-dependent linear factor, at different ambient temperatures. As can be seen in Fig. 5, the use of the static data (solid lines) in the LUT (Fig. 4) instead of the dynamic (dashed lines) leads to only minor differences in the results for the position determination at low demand voltages U. Le- only the data points for the end position 0 mm, i.e. at E3, differ significantly from the actual position x during the armature movement. However, the discrepancy between static and dynamic data increases with high voltages (and high anchor speeds). For a demand voltage U = 9 V, it is expected that the position determination will only deliver good results in the static case.
Bezugszeichenliste List of reference symbols
El, E2, E3 Endpositionen des Ankers 1 / A Stromstärke in Ampere max Strommesswert (Maximum) El, E2, E3 end positions of the armature 1 / A current in amperes max current measured value (maximum)
Imin Strommesswert (Minimum) Imin current measured value (minimum)
AI/At Stromänderungswert AI / At current change value
- DI/At / A s-1 negativer Stromänderungswert in Ampere pro Sekunde t / s Zeit in Sekunden tmax Zeit bei Messung Imax tmin Zeit bei Messung Imin u Spannung - DI / At / A s- 1 negative current change value in amperes per second t / s time in seconds tmax time when measuring I ma x tmin time when measuring I m in u voltage
Wl, W2, W3, W4 Wege des Ankers x (lineare) Position des Ankers x / m (lineare) Position des Ankers in Meter Wl, W2, W3, W4 Paths of the anchor x (linear) position of the anchor x / m (linear) position of the anchor in meters

Claims

Patentansprüche Claims
1. Verfahren zur Bestimmung der Position (x) eines Ankers eines elekt romagnetischen Linearaktuators, wobei der Anker linear in einer Spule des Linearaktuators beweglich ist, wobei die Spule zur Bewe gung des Ankers mit einem elektrischen Pulsweitenmodulations- Signal angesteuert wird, d a d u r c h g e k e n n z e i c h n e t , dass zwei Strommesswerte (Imax, Imin) während einer Periode des Pulsweiten- modulations-Signals gemessen werden, dass aus den zwei Strom messwerten (Imax, Imin) ein Stromänderungswert (DI/At) bestimmt wird, dass in einem Kennfeld eine Zuordnung von Stromände rungswerten (AI / At) zu Ankerpositionen (x) abgelegt ist, und dass mittels dieses Kennfelds die aktuelle Position (x) des Ankers zum Stromänderungswert (AI/At) bestimmt wird. 1. A method for determining the position (x) of an armature of an electromagnetic linear actuator, wherein the armature is linearly movable in a coil of the linear actuator, the coil for moving the armature is controlled with an electrical pulse width modulation signal, characterized in that two Current measured values (Imax, Imin) are measured during a period of the pulse width modulation signal so that a current change value (DI / At) is determined from the two current measured values (Imax, Imin) so that an assignment of current change values (AI / At) is stored for armature positions (x), and that the current position (x) of the armature for the current change value (AI / At) is determined by means of this map.
2. Verfahren nach Anspruch 1, d a d u r c h g e k e n n z e i c h n e t , dass der Stro mänderungswert (AI / At) sich auf die fallende Flanke des Pulswei- tenmodulations-Signals bezieht. 2. The method according to claim 1, d a d u r c h g e k e n n z e i c h n e t that the current change value (AI / At) relates to the falling edge of the pulse width modulation signal.
3. Verfahren nach zumindest einem der vorhergehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t , dass die zwei Strommesswerte (Imax, Imin) während einer Periode des Pulsweiten- modulations-Signals, die gemessen werden, ein Strommaximum (I- max) und ein Stromminimum (Imin) sind. 3. The method according to at least one of the preceding claims, characterized in that the two current measurement values (Imax, Imin) which are measured during a period of the pulse width modulation signal are a current maximum (I-max) and a current minimum (Imin).
4. Verfahren nach zumindest einem der vorhergehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t , dass die Be stimmung der Position (x) des Ankers während einer Linearbewe gung des Ankers erfolgt. 4. The method according to at least one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the determination of the position (x) of the armature takes place during a linear movement of the armature.
5. Verfahren nach zumindest einem der vorhergehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t , dass in dem Kennfeld eine Zuordnung von statischen, gemittelten Stromände rungswerten (DI/At) zu Ankerpositionen (x) abgelegt ist. 5. The method according to at least one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that an assignment of static, averaged current change values (DI / At) to armature positions (x) is stored in the map.
6. Verfahren nach zumindest einem der vorhergehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t , dass in dem Kennfeld eine Zuordnung von Stromänderungswerten (AI / At) zu An kerpositionen (x) für verschiedene Spannungen (U) oder verschiede ne Pulsweiten abgelegt ist. 6. The method according to at least one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that an assignment of current change values (AI / At) to armature positions (x) for different voltages (U) or different pulse widths is stored in the map.
7. Verfahren nach zumindest einem der vorhergehenden Ansprüche, d a d u r c h g e k e n n z e i c h n e t , dass das elekt rische Pulsweitenmodulations-Signal zur Ansteuerung der Spule stromgeregelt ist, so dass die Pulsweite des Pulsweitenmodulations- Signals von Periode zu Periode variiert. 7. The method according to at least one of the preceding claims, d a d u r c h g e k e n n z e i c h n e t that the electrical pulse width modulation signal for controlling the coil is current-regulated so that the pulse width of the pulse width modulation signal varies from period to period.
8. Verfahren nach Anspruch 6 und 7, d a d u r c h g e k e n n z e i c h n e t , dass eine mittle re aktuelle Pulsweite als Mittelwert über mehrere Perioden des Pulsweitenmodulations-Signals bestimmt wird und dass mittels des Kennfelds die aktuelle Position (x) des Ankers zum Stromände rungswert (AI/At) für die mittlere aktuelle Pulsweite bestimmt wird. 8. The method according to claim 6 and 7, characterized in that a mean current pulse width is determined as the mean value over several periods of the pulse width modulation signal and that by means of the map, the current position (x) of the armature to the current change value (AI / At) for the mean current pulse width is determined.
PCT/EP2020/076865 2019-09-25 2020-09-25 Method for determining the position of an armature of an electromagnetic linear actuator WO2021058723A1 (en)

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5578904A (en) * 1991-11-29 1996-11-26 Caterpillar Inc. Method and apparatus for determining the position of an armature of an electromagnetic actuator in response to the magnitude and time derivative of the actuator coil current
EP0908904A2 (en) * 1997-10-06 1999-04-14 Husco International, Inc. Method and apparatus for sensing armature position in reluctance electromagnetic actuators
DE102007016787A1 (en) 2007-04-05 2008-10-09 Schultz, Wolfgang E., Dipl.-Ing. Method for determination of anchor position in electromagnets, involves utilizing magnetic flow distribution for positioning, which is dependent on anchor position
WO2011121188A1 (en) * 2010-04-01 2011-10-06 Schneider Electric Industries Sas Electromagnetic actuator comprising position control means and method using such an actuator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5578904A (en) * 1991-11-29 1996-11-26 Caterpillar Inc. Method and apparatus for determining the position of an armature of an electromagnetic actuator in response to the magnitude and time derivative of the actuator coil current
EP0908904A2 (en) * 1997-10-06 1999-04-14 Husco International, Inc. Method and apparatus for sensing armature position in reluctance electromagnetic actuators
DE102007016787A1 (en) 2007-04-05 2008-10-09 Schultz, Wolfgang E., Dipl.-Ing. Method for determination of anchor position in electromagnets, involves utilizing magnetic flow distribution for positioning, which is dependent on anchor position
WO2011121188A1 (en) * 2010-04-01 2011-10-06 Schneider Electric Industries Sas Electromagnetic actuator comprising position control means and method using such an actuator

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