WO2008138663A1 - Method and device for limiting motor current - Google Patents

Method and device for limiting motor current Download PDF

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Publication number
WO2008138663A1
WO2008138663A1 PCT/EP2008/053158 EP2008053158W WO2008138663A1 WO 2008138663 A1 WO2008138663 A1 WO 2008138663A1 EP 2008053158 W EP2008053158 W EP 2008053158W WO 2008138663 A1 WO2008138663 A1 WO 2008138663A1
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WO
WIPO (PCT)
Prior art keywords
electric motor
motor
temperature
voltage
drive voltage
Prior art date
Application number
PCT/EP2008/053158
Other languages
German (de)
French (fr)
Inventor
Luc Heimlich
Michael Rummel
Marcellus Weber
Stephan Pauli
Florian Tisch
Original Assignee
Robert Bosch Gmbh
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Filing date
Publication date
Application filed by Robert Bosch Gmbh filed Critical Robert Bosch Gmbh
Publication of WO2008138663A1 publication Critical patent/WO2008138663A1/en

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P7/00—Arrangements for regulating or controlling the speed or torque of electric DC motors
    • H02P7/06—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current
    • H02P7/18—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power
    • H02P7/24—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices
    • H02P7/28—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices
    • H02P7/285—Arrangements for regulating or controlling the speed or torque of electric DC motors for regulating or controlling an individual dc dynamo-electric motor by varying field or armature current by master control with auxiliary power using discharge tubes or semiconductor devices using semiconductor devices controlling armature supply only
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B60—VEHICLES IN GENERAL
    • B60S—SERVICING, CLEANING, REPAIRING, SUPPORTING, LIFTING, OR MANOEUVRING OF VEHICLES, NOT OTHERWISE PROVIDED FOR
    • B60S1/00—Cleaning of vehicles
    • B60S1/02—Cleaning windscreens, windows or optical devices
    • B60S1/04—Wipers or the like, e.g. scrapers
    • B60S1/06—Wipers or the like, e.g. scrapers characterised by the drive
    • B60S1/08—Wipers or the like, e.g. scrapers characterised by the drive electrically driven
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P23/00—Arrangements or methods for the control of AC motors characterised by a control method other than vector control
    • H02P23/14—Estimation or adaptation of motor parameters, e.g. rotor time constant, flux, speed, current or voltage
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/02—Providing protection against overload without automatic interruption of supply
    • H02P29/032—Preventing damage to the motor, e.g. setting individual current limits for different drive conditions

Definitions

  • the invention relates to a method and a device for limiting the motor current.
  • today's electric motors are designed without current limiter circuits. This is the case, for example, in today's electronically controlled windscreen wiper motors.
  • Such electric motors are preferably designed to be blocked, i. that even with a complete blocking of the electric motor with applied voltage no current flows through the electric motor, which can lead to destruction.
  • Such an electric motor generally has a temperature monitoring in order to make a shutdown of the electric motor in a heavy load case and the resulting heating of the electric motor when a threshold temperature is exceeded.
  • the temperature monitoring is carried out, for example, with the aid of a thermal switch provided in the electric motor.
  • the maximum possible motor current (blocking current) is determined primarily by the resistance of the armature windings and is due to the material used, mainly copper, temperature dependent. Copper is a PTC thermistor, i. As the temperature increases, so does the electrical resistance of copper. That At low temperatures, the electrical resistance of the armature winding is lower. Thus, at low temperatures, the maximum possible motor current (in the case of blocking) sets in, while at high temperatures the maximum possible current is lower.
  • Such an electric motor must therefore be designed so that it can fulfill its function on the one hand in the upper temperature range, i. e.g. can provide the appropriate torque, and on the other hand, the entire system must be able to cope with the higher motor currents occurring at low temperatures.
  • a method for operating a jam-proof electric motor comprises determining an indication of the engine temperature, and providing a drive voltage for operating the electric motor depending on the indication of the engine temperature.
  • One idea of the invention is to adapt the voltage applied to the electric motor depending on the motor temperature, ie to control, so that when using a PTC thermistor as a winding material for the electric motor at low engine temperatures, a lower voltage is applied to the electric motor than at higher temperatures.
  • the motor current flowing through the electric motor can be limited by the voltage applied to the motor.
  • the maximum possible current consumption of the overall system can be limited and the load on the power supply network, ie in the case of a motor vehicle of the vehicle electrical system, decreases.
  • Another advantage is that in the case of a blockage, the motor demagnetization is reduced, since the strength of the magnetic field generated by the blocking current is lower than without the voltage adjustment. By reducing the torque at low temperature, the gearbox can be protected against overload.
  • a coil winding of the electric motor can have a PTC thermistor material, wherein the drive voltage is increased when the determined motor temperature rises.
  • the drive voltage may be chosen such that the torque is constant, i. the current through the coil windings of the electric motor is at a certain driving state of the electric motor (e.g.
  • Full load, stalling case and the like are controlled via the drive voltage of the electric motor so that the current is constant at each motor temperature.
  • the drive voltage can be regulated or controlled as a function of the motor temperature.
  • the drive voltage can be further controlled or regulated depending on a manipulated variable.
  • an engine system in particular for an electronic windscreen wiper system, is provided.
  • the motor system includes an electric motor, a temperature detection unit for detecting an indication of the engine temperature, and a drive unit for providing a drive voltage for the electric motor, wherein the drive unit is configured to generate the drive voltage depending on the indication of the engine temperature.
  • the electric motor may have a coil winding with a PTC thermistor material, wherein the drive unit has is formed to increase the driving voltage with an increase in the motor temperature.
  • the electric motor may be designed to be more blocked.
  • the drive unit can set the drive voltage so that the torque is constant.
  • the single figure shows a block diagram of an engine system 1 according to an embodiment of the invention.
  • the engine system 1 comprises an electric motor 2, in particular a DC electric motor, which can be controlled and operated with the aid of an output stage 3.
  • the output stage 3 may be formed for example in the form of an H-bridge, which determines the voltage applied to the electric motor 2 by a duty cycle of a clocking of a drive signal S in the output stage 3.
  • the drive signal S is provided to the output stage 3 on the input side.
  • the drive signal can be configured in this embodiment as a pulse-width-modulated signal whose duty cycle indicates the effective voltage U to be applied to the electric motor 2.
  • a temperature sensor 4 is provided which is coupled to a read-out unit 5, so that an engine temperature T prevailing in the electric motor 2 can be read out and is provided as a temperature indication.
  • the temperature sensor 4 for example, as a thermal resistor or may be provided.
  • the readout unit 5 determines the temperature indication by means of a resistance measurement of the temperature sensor.
  • the temperature indication can be in digital or analog form, eg in the form of a voltage representing the temperature indication.
  • An adaptation unit 6 is provided, which, depending on the temperature indication, which is received by the readout unit 5 and provides the drive signal S for the output stage 3 as a function of a likewise provided supply voltage V, by a corresponding drive voltage predetermined by the drive signal S. U to create the electric motor 2.
  • the drive signal S may be a variable voltage level with which the drive voltage U to be applied to the electric motor 2 is controlled in the output stage 3.
  • the adaptation unit 6, the output stage 3 and the electric motor 2 are designed such that, depending on the temperature input T, the voltage applied to the electric motor 2 is set.
  • the matching unit 6 outputs a drive signal to the electric motor 2, which increases the drive voltage U to be applied with increasing temperature of the electric motor 2, so that the increasing resistance of the winding material is compensated as.
  • the driving voltage U to be applied to the electric motor 2 can be increased with increasing temperature so that the maximum torque to be output by the electric motor 2 is kept as constant as possible becomes. That is, the current flowing in the windings of the electric motor is set to be equal to each temperature at a given given driving state of the electric motor.
  • the adaptation unit 6 can simulate the temperature behavior of the PTC thermistor essentially in the form of a characteristic curve of the PTC thermistor.
  • the characteristic curve of the PTC thermistor describes the dependence of the resistance on the temperature, so that the adaptation unit 6 carries out an assignment of the temperature specification to a component value of the voltage to be applied with respect to the maximum supply voltage.
  • the adaptation unit 6 can be designed as a control unit or as a control unit. If the adaptation unit 6 is designed as a control unit, a look-up table or a function can be stored in the adaptation unit 6, which applies (multiplies) the applied supply voltage to a multiplied value whose maximum value is 1, depending on the provided temperature is. This share value may e.g. be indicated by the duty cycle of the drive signal S.
  • the adaptation unit 6 can be designed as a control unit which, in addition to a proportional element, also includes integration elements or differentiating elements in order to be able to take into account the temporal behavior of the temperature profile in the electric motor 2.
  • the adaptation unit 6 preferably adjusts the drive voltage U applied to the electric motor 2 in such a way that the maximum motor current is limited to a maximum value. That is, the motor current in the blocking case of the motor is limited to a certain current determined by the drive signal. This has the advantage that less expensive circuit breakers for realizing the final level 3 can be used.
  • the strength of the magnetic field generated in the case of blocking is reduced by the current reduced due to the adjusted motor voltage, so that the demagnetization of permanent magnets in the electric motor can be reduced.
  • this manipulated variable can be offset with the proportion determined from the temperature specification provided by the readout unit 5 in order to obtain a drive variable S. , which takes into account both the motor temperature and the manipulated variable.
  • the manipulated variable can be multiplied by a component variable resulting from the temperature specification according to a function so as to obtain a drive signal S with which the voltage to be applied to the electric motor 2 is determined from the maximum supply voltage.
  • the adjustment of the drive voltage U described above is particularly useful in electric motors that are not provided with a current control or regulation, and therefore a limitation of the maximum current flow through the adaptation of the applied drive voltage U must be made.

Abstract

The invention relates to a method for operating a non-stalling electric motor (2), comprising the following steps: determining an indication of the motor temperature (T); providing an actuating voltage for operating the electric motor depending on the indication of the motor temperature (T), a coil winding of the electric motor (2) comprising a cold conducting material (such as copper), the actuating voltage being increased when the determined motor temperature increases, and the actuating voltage being selected such that the torque is constant.

Description

ROBERT BOSCH GMBH, 70442 StuttgartROBERT BOSCH GMBH, 70442 Stuttgart
Beschreibungdescription
Titeltitle
Verfahren und Vorrichtung zur Begrenzung des MotorstromsMethod and device for limiting the motor current
Die Erfindung betrifft ein Verfahren und eine Vorrichtung zur Begrenzung des Motorstroms.The invention relates to a method and a device for limiting the motor current.
Je nach Anwendungsgebiet und Bauart sind heutige Elektromotoren ohne Strombegrenzerschaltungen ausgeführt. Dies ist bei- spielsweise bei heutigen elektronisch gesteuerten Scheibenwischermotoren der Fall. Solche Elektromotoren sind vorzugsweise blockierfest ausgelegt, d.h. dass selbst bei einem vollständigem Blockieren des Elektromotors bei anliegender Spannung kein Strom durch den Elektromotor fließt, der zu einer Zerstörung führen kann.Depending on the field of application and design, today's electric motors are designed without current limiter circuits. This is the case, for example, in today's electronically controlled windscreen wiper motors. Such electric motors are preferably designed to be blocked, i. that even with a complete blocking of the electric motor with applied voltage no current flows through the electric motor, which can lead to destruction.
Ein solcher Elektromotor weist in der Regel eine Temperaturüberwachung auf, um in einem Schwerlastfall und der daraus resultierenden Erwärmung des Elektromotors eine Abschaltung des Elektromotors vornehmen zu können, wenn eine Schwellentemperatur überschritten wird. Die Temperaturüberwachung wird beispielsweise mit Hilfe eines im Elektromotor vorgesehenen Thermoschalters durchgeführt.Such an electric motor generally has a temperature monitoring in order to make a shutdown of the electric motor in a heavy load case and the resulting heating of the electric motor when a threshold temperature is exceeded. The temperature monitoring is carried out, for example, with the aid of a thermal switch provided in the electric motor.
Da keine Strombegrenzung vorgesehen ist, können je nach anliegender mechanischer Last Ströme bis hin zu dem maximalen Blockierstrom, der bei vollständig blockiertem Rotor fließt, auftreten, da durch die Temperaturüberwachung der Motorstrom nicht in seiner Höhe, sondern nur in der Dauer, während der dieser Strom durch den Elektromotor fließt, begrenzt wird.Since no current limiting is provided, currents up to the maximum blocking current that flows when the rotor is completely blocked can occur, depending on the applied mechanical load, since the temperature monitoring monitors the motor current not in its height, but only in the duration during which this current flows through the electric motor is limited.
Der maximal mögliche Motorstrom (Blockierstrom) bestimmt sich in erster Linie durch den Widerstand der Ankerwicklungen und ist aufgrund des verwendeten Materials, vorwiegend Kupfer, temperaturabhängig. Kupfer ist ein Kaltleiter, d.h. mit steigender Temperatur steigt auch der elektrische Widerstand von Kupfer an. D.h. bei tiefen Temperaturen ist der elektrische Widerstand der Ankerwicklung geringer. So stellt sich bei tiefen Temperaturen der maximal mögliche Motorstrom (im Blockierfall) ein, während bei hohen Temperaturen der maximal mögliche Strom geringer ist.The maximum possible motor current (blocking current) is determined primarily by the resistance of the armature windings and is due to the material used, mainly copper, temperature dependent. Copper is a PTC thermistor, i. As the temperature increases, so does the electrical resistance of copper. That At low temperatures, the electrical resistance of the armature winding is lower. Thus, at low temperatures, the maximum possible motor current (in the case of blocking) sets in, while at high temperatures the maximum possible current is lower.
Ein derartiger Elektromotor muss daher so ausgelegt werden, dass er einerseits im oberen Temperaturbereich seine Funktion erfüllen kann, d.h. z.B. das entsprechende Drehmoment bereitstellen kann, und andererseits muss das Gesamtsystem die bei tiefen Temperaturen auftretenden höheren Motorströme verkraf- ten können.Such an electric motor must therefore be designed so that it can fulfill its function on the one hand in the upper temperature range, i. e.g. can provide the appropriate torque, and on the other hand, the entire system must be able to cope with the higher motor currents occurring at low temperatures.
Weiterhin treten bei niedrigen Temperaturen aufgrund der höheren Ströme sehr hohe Drehmomente auf, die unter Umständen größer sind als die von einem mit dem Motor verbundenen Ge- triebe zulässigen Drehmomente, sodass bei niedrigen Temperaturen und bei Anliegen großer Last über das Getriebe Schäden durch ein zu hohes vom Motor abgegebenes Drehmoment auftreten können .Furthermore, at low temperatures, due to the higher currents, very high torques may occur, which may be greater than those permitted by a gearbox connected to the engine, resulting in excessive damage at low temperatures and high gear load Torque emitted by the engine may occur.
Es ist daher Aufgabe der vorliegenden Erfindung, ein Verfahren zum Betreiben eines Elektromotors sowie einen Elektromotor zur Verfügung zu stellen, wobei der maximale Motorstrom begrenzt werden kann, ohne dass z.B. eine aufwändige Strombe- grenzungsschaltung bzw. Drehmomentbegrenzungsschaltung und dergleichen vorgesehen werden muss.It is therefore an object of the present invention to provide a method for operating an electric motor and an electric motor, wherein the maximum motor current can be limited without, for example, a complex current limit circuit or torque limiting circuit and the like must be provided.
Offenbarung der ErfindungDisclosure of the invention
Diese Aufgabe wird durch das Verfahren zum Betreiben eines Elektromotors nach Anspruch 1 sowie durch das Motorsystem gemäß dem nebengeordneten Anspruch gelöst.This object is achieved by the method for operating an electric motor according to claim 1 and by the motor system according to the independent claim.
Weitere vorteilhafte Ausgestaltungen der Erfindung sind in den abhängigen Ansprüchen angegeben.Further advantageous embodiments of the invention are specified in the dependent claims.
Gemäß einem ersten Aspekt ist ein Verfahren zum Betreiben eines blockiersicheren Elektromotors vorgesehen. Das Verfahren umfasst das Ermitteln einer Angabe über die Motortemperatur, sowie das Bereitstellen einer Ansteuerspannung zum Betreiben des Elektromotors abhängig von der Angabe über die Motortemperatur .According to a first aspect, a method for operating a jam-proof electric motor is provided. The method comprises determining an indication of the engine temperature, and providing a drive voltage for operating the electric motor depending on the indication of the engine temperature.
Eine Idee der Erfindung besteht darin, die an dem Elektromotor angelegte Spannung abhängig von der Motortemperatur anzupassen, d.h. zu steuern bzw. zu regeln, sodass bei Verwendung eines Kaltleiters als Wicklungsmaterial für den Elektromotor bei niedrigen Motortemperaturen eine geringere Spannung an den Elektromotor angelegt wird als bei höheren Temperaturen. Auf diese Weise kann der durch den Elektromotor fließende Motorstrom durch die an den Motor angelegte Spannung begrenzt werden. Dadurch kann die maximal mögliche Stromaufnahme des Gesamtsystems begrenzt werden und die Belastung des Stromver- sorgungsnetzes, d.h. im Falle eines Kraftfahrzeugs des Bordnetzes, sinkt. Weiterhin können dadurch, dass die maximal möglichen Ströme in dem Elektromotor reduziert werden, preisgünstigere Leistungsschalter für die Endstufe des Elektromo- tors verwendet werden. Ein weiterer Vorteil besteht darin, dass im Blockierfall die Motorentmagnetisierung reduziert ist, da die Stärke des durch den Blockierstrom erzeugten Magnetfeldes geringer ist als ohne die Spannungsanpassung. Durch die Reduzierung des Drehmoments bei niedriger Temperatur kann das Getriebe vor Überlast geschützt werden.One idea of the invention is to adapt the voltage applied to the electric motor depending on the motor temperature, ie to control, so that when using a PTC thermistor as a winding material for the electric motor at low engine temperatures, a lower voltage is applied to the electric motor than at higher temperatures. In this way, the motor current flowing through the electric motor can be limited by the voltage applied to the motor. As a result, the maximum possible current consumption of the overall system can be limited and the load on the power supply network, ie in the case of a motor vehicle of the vehicle electrical system, decreases. Furthermore, by the fact that the maximum possible currents are reduced in the electric motor, cheaper power switches for the output stage of the electric motor be used. Another advantage is that in the case of a blockage, the motor demagnetization is reduced, since the strength of the magnetic field generated by the blocking current is lower than without the voltage adjustment. By reducing the torque at low temperature, the gearbox can be protected against overload.
Weiterhin kann eine Spulenwicklung des Elektromotors ein Kaltleitermaterial aufweisen, wobei die Ansteuerspannung er- höht wird, wenn die ermittelte Motortemperatur ansteigt.Furthermore, a coil winding of the electric motor can have a PTC thermistor material, wherein the drive voltage is increased when the determined motor temperature rises.
Gemäß einer Ausführungsform kann die Ansteuerspannung so gewählt werden, dass das Drehmoment konstant ist, d.h. der Strom durch die Spulenwicklungen des Elektromotors wird bei einem bestimmten Ansteuerzustand des Elektromotors (z.B.According to one embodiment, the drive voltage may be chosen such that the torque is constant, i. the current through the coil windings of the electric motor is at a certain driving state of the electric motor (e.g.
Volllast, Blockierfall und dergleichen) über die Ansteuerspannung des Elektromotors so gesteuert, dass der Strom bei jeder Motortemperatur konstant ist. Insbesondere kann die Ansteuerspannung abhängig von der Motortemperatur geregelt oder gesteuert werden. Weiterhin kann die Ansteuerspannung weiter abhängig von eine Stellgröße gesteuert oder geregelt werden.Full load, stalling case and the like) are controlled via the drive voltage of the electric motor so that the current is constant at each motor temperature. In particular, the drive voltage can be regulated or controlled as a function of the motor temperature. Furthermore, the drive voltage can be further controlled or regulated depending on a manipulated variable.
Gemäß einem weiteren Aspekt ist ein Motorsystem, insbesondere für ein elektronisches Scheibenwischersystem, vorgesehen. Das Motorsystem umfasst einen Elektromotor, eine Temperaturerfassungseinheit zur Erfassung einer Angabe über die Motortemperatur und eine Ansteuereinheit zum Bereitstellen einer Ansteuerspannung für den Elektromotor, wobei die Ansteuereinheit ausgebildet ist, um die Ansteuerspannung abhängig von der Angabe über die Motortemperatur zu erzeugen.According to a further aspect, an engine system, in particular for an electronic windscreen wiper system, is provided. The motor system includes an electric motor, a temperature detection unit for detecting an indication of the engine temperature, and a drive unit for providing a drive voltage for the electric motor, wherein the drive unit is configured to generate the drive voltage depending on the indication of the engine temperature.
Weiterhin kann der Elektromotor eine Spulenwicklung mit einem Kaltleitermaterial aufweisen, wobei die Ansteuereinheit aus- gebildet ist, um bei einer Erhöhung der Motortemperatur die Ansteuerspannung zu erhöhen.Furthermore, the electric motor may have a coil winding with a PTC thermistor material, wherein the drive unit has is formed to increase the driving voltage with an increase in the motor temperature.
Gemäß einer Ausführungsform kann der Elektromotor blockiersi- eher ausgelegt sein.According to one embodiment, the electric motor may be designed to be more blocked.
Weiterhin kann die Ansteuereinheit die Ansteuerspannung so einstellen, dass das Drehmoment konstant ist.Furthermore, the drive unit can set the drive voltage so that the torque is constant.
Beschreibung der AusführungsformenDescription of the embodiments
Bevorzugte Ausführungsformen werden nachfolgend anhand der beigefügten Zeichnung näher erläutert.Preferred embodiments will be explained in more detail with reference to the accompanying drawings.
Die einzige Figur zeigt ein Blockschaltbild eines Motorsystems 1 gemäß einer Ausführungsform der Erfindung. Das Motorsystem 1 umfasst einen Elektromotor 2, insbesondere einen DC- Elektromotor, der mit Hilfe einer Endstufe 3 angesteuert und betrieben werden kann. Die Endstufe 3 kann beispielsweise in Form einer H-Brücke ausgebildet sein, die die am Elektromotor 2 anliegende Spannung durch ein Tastverhältnis einer Taktung eines Ansteuersignals S in der Endstufe 3 bestimmt. Das Ansteuersignal S wird der Endstufe 3 eingangsseitig bereitgestellt. Das Ansteuersignal kann bei dieser Ausführungsform als ein pulsweitenmoduliertes Signal ausgestaltet sein, dessen Tastverhältnis die effektiv an dem Elektromotor 2 anzulegende Spannung U angibt .The single figure shows a block diagram of an engine system 1 according to an embodiment of the invention. The engine system 1 comprises an electric motor 2, in particular a DC electric motor, which can be controlled and operated with the aid of an output stage 3. The output stage 3 may be formed for example in the form of an H-bridge, which determines the voltage applied to the electric motor 2 by a duty cycle of a clocking of a drive signal S in the output stage 3. The drive signal S is provided to the output stage 3 on the input side. The drive signal can be configured in this embodiment as a pulse-width-modulated signal whose duty cycle indicates the effective voltage U to be applied to the electric motor 2.
In dem Elektromotor 2 ist ein Temperatursensor 4 vorgesehen, der mit einer Ausleseeinheit 5 gekoppelt ist, sodass eine in dem Elektromotor 2 herrschende Motortemperatur T auslesbar ist und als Temperaturangabe bereitgestellt wird. Der Temperatursensor 4 kann beispielsweise als Thermowiderstand oder dergleichen vorgesehen sein. Die Ausleseeinheit 5 ermittelt in diesem Fall die Temperaturangabe durch eine Widerstandsmessung des Temperatursensors. Die Temperaturangabe kann in digitaler oder analoger Form, z.B. in Form einer die Tempera- turangabe repräsentierenden Spannung.In the electric motor 2, a temperature sensor 4 is provided which is coupled to a read-out unit 5, so that an engine temperature T prevailing in the electric motor 2 can be read out and is provided as a temperature indication. The temperature sensor 4, for example, as a thermal resistor or may be provided. In this case, the readout unit 5 determines the temperature indication by means of a resistance measurement of the temperature sensor. The temperature indication can be in digital or analog form, eg in the form of a voltage representing the temperature indication.
Es ist eine Anpassungseinheit 6 vorgesehen, die abhängig von der Temperaturangabe, die von der Ausleseeinheit 5 empfangen wird und abhängig von einer ebenfalls bereitgestellten Ver- sorgungsspannung V das Ansteuersignal S für die Endstufe 3 zur Verfügung stellt, um eine entsprechende durch das Ansteuersignal S vorgegebene Ansteuerspannung U an den Elektromotor 2 anzulegen.An adaptation unit 6 is provided, which, depending on the temperature indication, which is received by the readout unit 5 and provides the drive signal S for the output stage 3 as a function of a likewise provided supply voltage V, by a corresponding drive voltage predetermined by the drive signal S. U to create the electric motor 2.
Alternativ kann das Ansteuersignal S ein variabler Spannungspegel sein, mit dem in der Endstufe 3 die an den Elektromotor 2 anzulegende Ansteuerspannung U gesteuert wird. Allgemein ist die Anpassungseinheit 6, die Endstufe 3 und der Elektromotor 2 so ausgebildet, dass abhängig von der Temperaturanga- be T die an dem Elektromotor 2 anliegende Spannung eingestellt wird.Alternatively, the drive signal S may be a variable voltage level with which the drive voltage U to be applied to the electric motor 2 is controlled in the output stage 3. In general, the adaptation unit 6, the output stage 3 and the electric motor 2 are designed such that, depending on the temperature input T, the voltage applied to the electric motor 2 is set.
Handelt es sich bei dem Elektromotor 2 um einen Elektromotor mit Wicklungen aus einem Kaltleitermaterial, wie z.B. Kupfer, so steigt der ohmsche Wicklungswiderstand mit steigender Temperatur an. Daher gibt die Anpassungseinheit 6 ein Ansteuersignal an den Elektromotor 2 aus, das die anzulegende Ansteuerspannung U bei steigender Temperatur des Elektromotors 2 erhöht, so dass der steigende Widerstand des Wicklungsmateri- als ausgeglichen wird. Beispielsweise kann die an dem Elektromotor 2 anzulegende Ansteuerspannung U so mit steigender Temperatur erhöht werden, dass das maximale von dem Elektromotor 2 abzugebende Drehmoment möglichst konstant gehalten wird. Dies bedeutet, dass der in den Wicklungen des Elektromotors fließende Strom so eingestellt ist, dass er bei einem bestimmten gegebenen Ansteuerzustand des Elektromotors für jede Temperatur gleich ist. In diesem Fall kann z.B. die An- passungseinheit 6 das Temperaturverhalten des Kaltleiters im wesentlichen in Form einer Kennlinie des Kaltleiters nachbilden. Die Kennlinie des Kaltleiters beschreibt die Abhängigkeit des Widerstands über der Temperatur, so dass die Anpassungseinheit 6 eine Zuordnung der Temperaturangabe zu einem Anteilswert der anzulegenden Spannung bezüglich der maximalen Versorgungsspannung vornimmt.If the electric motor 2 is an electric motor with windings of a cold conductor material, such as copper, the ohmic winding resistance increases with increasing temperature. Therefore, the matching unit 6 outputs a drive signal to the electric motor 2, which increases the drive voltage U to be applied with increasing temperature of the electric motor 2, so that the increasing resistance of the winding material is compensated as. For example, the driving voltage U to be applied to the electric motor 2 can be increased with increasing temperature so that the maximum torque to be output by the electric motor 2 is kept as constant as possible becomes. That is, the current flowing in the windings of the electric motor is set to be equal to each temperature at a given given driving state of the electric motor. In this case, for example, the adaptation unit 6 can simulate the temperature behavior of the PTC thermistor essentially in the form of a characteristic curve of the PTC thermistor. The characteristic curve of the PTC thermistor describes the dependence of the resistance on the temperature, so that the adaptation unit 6 carries out an assignment of the temperature specification to a component value of the voltage to be applied with respect to the maximum supply voltage.
Die Anpassungseinheit 6 kann als Regeleinheit oder als Steuereinheit ausgebildet sein. Im Falle, dass die Anpassungsein- heit 6 als Steuereinheit ausgebildet ist, kann in der Anpassungseinheit 6 eine Lookup-Tabelle oder eine Funktion hinterlegt sein, die abhängig von der bereitgestellten Temperaturangabe die anliegende Versorgungsspannung mit einem Anteilswert beaufschlagt (multipliziert) , dessen maximaler Wert 1 beträgt. Dieser Anteilswert kann z.B. durch das Tastverhältnis des Ansteuersignals S angegeben sein.The adaptation unit 6 can be designed as a control unit or as a control unit. If the adaptation unit 6 is designed as a control unit, a look-up table or a function can be stored in the adaptation unit 6, which applies (multiplies) the applied supply voltage to a multiplied value whose maximum value is 1, depending on the provided temperature is. This share value may e.g. be indicated by the duty cycle of the drive signal S.
Weiterhin kann die Anpassungseinheit 6 als Regeleinheit ausgebildet sein, die neben einem Proportionalglied auch Integ- rationsglieder oder Differenzierglieder umfasst, um auch das zeitliche Verhalten des Temperaturverlaufs im Elektromotor 2 berücksichtigen zu können. Vorzugsweise stellt die Anpassungseinheit 6 die an dem Elektromotor 2 anliegende Ansteuerspannung U so ein, dass der maximale Motorstrom auf einen Ma- ximalwert beschränkt ist. D.h., der Motorstrom im Blockierfall des Motors ist auf einem bestimmten von dem Ansteuersignal bestimmten Strom begrenzt. Dies hat den Vorteil, dass preisgünstigere Leistungsschalter zur Realisierung der End- stufe 3 verwendet werden können. Weiterhin ist die Stärke des im Blockierfall erzeugte Magnetfeld durch den aufgrund der angepassten Motorspannung reduzierten Stroms verringert, so dass die Entmagnetisierung von Permanentmagneten im Elektro- motor reduziert werden kann.Furthermore, the adaptation unit 6 can be designed as a control unit which, in addition to a proportional element, also includes integration elements or differentiating elements in order to be able to take into account the temporal behavior of the temperature profile in the electric motor 2. The adaptation unit 6 preferably adjusts the drive voltage U applied to the electric motor 2 in such a way that the maximum motor current is limited to a maximum value. That is, the motor current in the blocking case of the motor is limited to a certain current determined by the drive signal. This has the advantage that less expensive circuit breakers for realizing the final level 3 can be used. Furthermore, the strength of the magnetic field generated in the case of blocking is reduced by the current reduced due to the adjusted motor voltage, so that the demagnetization of permanent magnets in the electric motor can be reduced.
Wenn die Anpassungseinheit 6 weiterhin eine Stellgröße von einem übergeordneten Steuersystem erhält, um den Elektromotor mit variablen Drehmoment/Drehzahl zu betreiben, so kann diese Stellgröße mit der sich aus der von der Ausleseeinheit 5 bereitgestellten Temperaturangabe bestimmten Anteilgröße verrechnet werden, um eine Ansteuergröße S zu erhalten, die sowohl die Motortemperatur als auch die Stellgröße berücksichtigt. Beispielsweise kann die Stellgröße mit einer sich aus der Temperaturangabe gemäß einer Funktion ergebenden Anteilsgröße multipliziert werden, um so ein Ansteuersignal S zu erhalten, mit dem die an den Elektromotor 2 anzulegende Spannung aus der maximalen Versorgungsspannung bestimmt wird.If the adaptation unit 6 continues to receive a manipulated variable from a higher-level control system in order to operate the electric motor with variable torque / rotational speed, then this manipulated variable can be offset with the proportion determined from the temperature specification provided by the readout unit 5 in order to obtain a drive variable S. , which takes into account both the motor temperature and the manipulated variable. For example, the manipulated variable can be multiplied by a component variable resulting from the temperature specification according to a function so as to obtain a drive signal S with which the voltage to be applied to the electric motor 2 is determined from the maximum supply voltage.
Die oben beschriebene Anpassung der Ansteuerspannung U ist insbesondere bei Elektromotoren sinnvoll, die nicht mit einer Stromsteuerung bzw. -regelung versehen sind, und daher eine Begrenzung des maximalen Stromflusses durch die Anpassung der angelegten Ansteuerspannung U erfolgen muss. The adjustment of the drive voltage U described above is particularly useful in electric motors that are not provided with a current control or regulation, and therefore a limitation of the maximum current flow through the adaptation of the applied drive voltage U must be made.

Claims

Patentansprüche claims
1. Verfahren zum Betreiben eines blockiersicheren Elektromotors (2), mit folgenden Schritten: - Ermitteln einer Angabe über die Motortemperatur (T) ;A method of operating a jam-proof electric motor (2), comprising the steps of: - determining an indication of the engine temperature (T);
- Bereitstellen einer Ansteuerspannung zum Betreiben des Elektromotors abhängig von der Angabe über die Motortemperatur (T) .- Providing a drive voltage for operating the electric motor depending on the indication of the engine temperature (T).
2. Verfahren nach Anspruch 1, wobei eine Spulenwicklung des Elektromotors (2) ein Kaltleitermaterial aufweist, wobei die Ansteuerspannung erhöht wird, wenn die ermittelte Motortemperatur ansteigt.2. The method of claim 1, wherein a coil winding of the electric motor (2) comprises a PTC thermistor, wherein the driving voltage is increased when the determined motor temperature increases.
3. Verfahren nach Anspruch 2, wobei die Ansteuerspannung so gewählt wird, dass das Drehmoment konstant ist. 3. The method of claim 2, wherein the drive voltage is selected so that the torque is constant.
4. Verfahren nach einem der Ansprüche 1 bis 3, wobei die Ansteuerspannung abhängig von der Motortemperatur geregelt oder gesteuert wird.4. The method according to any one of claims 1 to 3, wherein the driving voltage is regulated or controlled depending on the engine temperature.
5. Verfahren nach einem der Ansprüche 1 bis 4, wobei die Ansteuerspannung weiter abhängig von eine Stellgröße gesteu- ert oder geregelt wird.5. The method according to any one of claims 1 to 4, wherein the drive voltage is further controlled or regulated depending on a manipulated variable.
6. Motorsystem (1), insbesondere für ein elektronisches ScheibenwischerSystem, umfassend:6. Engine system (1), in particular for an electronic windshield wiper system, comprising:
- einen Elektromotor (2);- An electric motor (2);
- eine Temperaturerfassungseinheit (4, 5) zur Erfassung einer Angabe über die Motortemperatur; und- A temperature detection unit (4, 5) for detecting an indication of the engine temperature; and
- eine Ansteuereinheit (6, 3) zum Bereitstellen einer Ansteuerspannung für den Elektromotor, wobei die Ansteuereinheit (6, 3) ausgebildet ist, um die Ansteuerspannung abhängig von der Angabe über die Motortemperatur (T) zu erzeugen.- A drive unit (6, 3) for providing a drive voltage for the electric motor, wherein the drive unit (6, 3) is designed to generate the drive voltage depending on the indication of the motor temperature (T).
7. Motorsystem nach Anspruch 6, wobei der Elektromotor (2) eine Spulenwicklung mit einem Kaltleitermaterial aufweist, wobei die Ansteuereinheit (6, 3) ausgebildet ist, um bei einer Erhöhung der Motortemperatur die Ansteuerspannung zu erhöhen .7. Motor system according to claim 6, wherein the electric motor (2) has a coil winding with a PTC thermistor, wherein the drive unit (6, 3) is formed to at an increase in the motor temperature to increase the drive voltage.
8. Motorsystem nach Anspruch 6 oder 7, wobei der Elektromotor8. Motor system according to claim 6 or 7, wherein the electric motor
(2) blockiersicher ausgelegt ist.(2) designed to be secure against blocking.
9. Motorsystem nach einem der Ansprüche 6 bis 8, wobei die Ansteuereinheit (6, 3) die Ansteuerspannung so einstellt, dass das Drehmoment konstant ist. 9. Motor system according to one of claims 6 to 8, wherein the drive unit (6, 3) sets the drive voltage so that the torque is constant.
PCT/EP2008/053158 2007-05-11 2008-03-17 Method and device for limiting motor current WO2008138663A1 (en)

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DE102011004886A1 (en) 2011-03-01 2012-09-06 Robert Bosch Gmbh Device for measuring temperature of coil winding in electronically commutated electric machine e.g. motor used in internal combustion engine, has driver circuit whose semiconductor switches are operated as power supply unit components

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DE102004046626A1 (en) * 2004-09-25 2006-03-30 Robert Bosch Gmbh Brushless electric motor e.g. drive servo motor, control unit for motor vehicle, has control device to output control signal based on comparison of motor-actual value with motor-reference value and controllable by brushless electric motor

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DE10101213A1 (en) * 2001-01-11 2002-07-18 Heinzmann Gmbh Co Kg Fritz Light vehicle especially an electric bicycle has a temperature sensor and electronic unit to control the electric motor output
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