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EP1153473A1 - Procede et dispositif servant a commander un electromoteur - Google Patents

Procede et dispositif servant a commander un electromoteur

Info

Publication number
EP1153473A1
EP1153473A1 EP99951350A EP99951350A EP1153473A1 EP 1153473 A1 EP1153473 A1 EP 1153473A1 EP 99951350 A EP99951350 A EP 99951350A EP 99951350 A EP99951350 A EP 99951350A EP 1153473 A1 EP1153473 A1 EP 1153473A1
Authority
EP
European Patent Office
Prior art keywords
rotary speed
electric motor
microprocessor
power
supplied
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP99951350A
Other languages
German (de)
English (en)
Inventor
Hans Birger Ericsson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Nord 2000 Intressenter AB
Original Assignee
Nord 2000 Intressenter AB
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Nord 2000 Intressenter AB filed Critical Nord 2000 Intressenter AB
Publication of EP1153473A1 publication Critical patent/EP1153473A1/fr
Withdrawn legal-status Critical Current

Links

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
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/16—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters
    • H02P1/26—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor
    • H02P1/28—Arrangements for starting electric motors or dynamo-electric converters for starting dynamo-electric motors or dynamo-electric converters for starting an individual polyphase induction motor by progressive increase of voltage applied to primary circuit of motor
    • 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
    • H02P27/00—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage
    • H02P27/02—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using supply voltage with constant frequency and variable amplitude
    • H02P27/026—Arrangements or methods for the control of AC motors characterised by the kind of supply voltage using supply voltage with constant frequency and variable amplitude whereby the speed is regulated by measuring the motor speed and comparing it with a given physical value

Definitions

  • the present invention relates to a method and a device for controlling an electric motor arranged to serve as a drive source for electrically driven hand tools or stationary machinery, which are made subject to varying loads during operation.
  • the invention is in this connection particularly well adapted for circular saws having two adjacent saw blades rotating in an opposed relationship, but it is in no way restricted to such use.
  • electrically driven hand tools such as circular saws or similar
  • a method to monitor whether or not there is a risk for overloading the drive motor is obviously surveillance of the temperature of the drive motor, and to interrupt the drive voltage when the temperature exceeds a predetermined maximum value.
  • such a solution can only be used to avoid that the drive motor is being damaged by overheating, and does not cause any adaption of supplied power to the drive motor based on the different operating conditions and rotary speeds which occur during use, e.g. due to the material and thickness of the workpiece, as well as the pressure applied/feeding speed.
  • the object of the present invention is to disclose a method and a device for controlling an electric drive motor with adaption of the drive motor power to required rotary speed for different operating conditions, whereby the drive motor power can be used to a maximum level without risk of overloading.
  • a further object is to secure a substantially constant rotary speed adapted to actual operative load.
  • the present invention is also intended to secure that the drive motor is not damaged when the rotation of the drive motor is prevented, during startup as well as during operation.
  • the method according to the present invention for control of an electric motor arranged to serve as drive source for electrically driven hand tools or stationary machines, which during operation are made subject to varying loads is mainly characterized in that limit values, determined by experience and/or calculations, relating to supplied power with regard to different rotary speeds stored in one or a number of memory circuits are compared to present actual rotary speed and supplied power with use of a microprocessor, that an output signal from the microprocessor is used to adjust supplied power within preset limits for each rotary speed as compensation for reductions in rotary speed due to increased load and increases in rotary speed due to reduced load, and that overstepping orunderstepping stored limit values during a predetermined time period set for each group of limit values being arranged to cause disconnection of the drive voltage fed to the electric motor.
  • a start operation including two or more steps with time surveillance during which the microprocessor step by step increases supplied power and performs comparison between to the microprocessor supplied information relating to obtained rotary speed and stored information relating to expected rotary speed for each step, a rotary speed lower than stored speed information during a predetermined time period being arranged to cause disconnection of the drive voltage fed to the electric motor.
  • the device for utilization of the method according to the present invention is defined by the characteristic features disclosed in claim 6 and related subclaims.
  • Fig. 1 is a diagram intended to serve as an example of an operating case for an electrically driven portable circular saw
  • Fig. 2 is a flow chart intended to illustrate an example of how a starting operation is carried out according to the method of the present invention.
  • Fig. 3 is a flow chart intended to illustrate how the method according to the present invention is utilized during an operation.
  • FIG. 1 a diagram is shown intended to illustrate an example of an operative case for a circular saw of above stated type.
  • a manually operable switching means is influenced in a known fashion, whereby a voltage is fed to the motor of the circular saw, an operation performed at 1.
  • the circular saw is arranged with a sensor reading present rotary speed, e.g. a magnet located in a hole extending crosswise through the motor shaft, arranged to influence an adjacently located stationary Hall-element.
  • a sensor reading present rotary speed e.g. a magnet located in a hole extending crosswise through the motor shaft, arranged to influence an adjacently located stationary Hall-element.
  • the method according to the present invention also uses a microprocessor with associated storage means for data, which advantageously may be one or a number of memory circuits of a memory type facilitating reprogramming, e.g. flash memory.
  • a control means is also used for controlling supplied power, preferably of semiconductor type, e.g. triacs.
  • the above mention memory circuit is programmed with a table based on values obtained through tests or values calculated for the actual type of saw, i.e. relating to allowed rotary speeds, and for such speeds acceptable levels of supplied power. Also time values for a starting operation are advantageously decided and stored, as well as time values with regard to expected response to changes in power.
  • a clocked period starts (time period 1 in Fig. 2), e.g. 0.05 seconds, during which restricted power is being supplied to the motor and surveillance is carried out in order to establish if a pulse train is received as a reply confirming rotation of the motor shaft (the saw blades).
  • a second clock period is advantageously initiated (time period 2 in Fig. 2), and a further control whether or not rotation has commenced is carried out. Should this not be the case, the current supply to the motor is interrupted, and the problem is advantageously indicated acoustically or optically to the operator, e.g. by means of buzzer, display unit or similar. In this case, the saw blades are probably incorrectly mounted or by any other reason prevented from rotating.
  • a small reduction of rotary speed and power is indicated between points 8 and 9 in Fig. 1 , e.g. when sawing thin sheet metal, and new table data are fetched which result in a suitably strong machine, suited for sawing in such a material and utilizing a relatively high rotary speed.
  • the range between points 12 to 15 in Fig. 1 is intended to serve as an example of conventional sawing with a finally increased load. Since this increased load eventually as a result means that stored table values are exceeded (within the range 15 to 16), the voltage fed to the motor is interrupted at 16, since stored information relating to maximum supplied power (Pmax) is exceeded during a predetermined time period.
  • the above described action after completed and accepted start operation can also be described with reference to the flow chart in Fig. 3.
  • the rotary speed after completed start operation (indicated by the downwardly directed arrow) is a first present rotary speed (N). After a clock ed period X the rotary speed (N) is compared with the new rotary speed (Nx) obtained,
  • the value (Nz) is hereafter a new input value (N), and provided that (N) is not less than a predetermined minimum rotary speed (Nmin), (N) will serve as a new input value to be monitored during the period x and to be compared with the rotary speed (Nx).
  • Fig. 3 shows primarily the method according to the present invention within the range 7 - 16 in Fig. 1 , whereas Fig. 2 discloses the start operation according to the range 1 - 7 in said figure.
  • Discussed actions are thus based on stored table values relating to supplied power and rotary speeds, as well as stored information of time intervals, primarily for a start operation but also with regard to surveillance intervals.
  • micropro- cessor which can increase and decrease the opening angle for utilized triacs or similar semiconductors on basis of stored table values for different rotary speeds, which is obtained by the microprocessor as a pulse train with a frequency related to present rotary speed.
  • stored table values also a number of time monitoring functions, arranged to start a clock period during which surveillance is carried out with regard to changes in rotary speed, if a predetermined maximum power value is maintained exceeded during more than one or a number of accepted clock periods (time periods), and if such parameters are exceeded, this would also result in disconnection of the voltage fed to the motor in order to protect the motor and other included components against damage caused by overload.
  • Disconnection of the voltage fed to the motor is advantageously arranged to cause a fast acting braking action, a possibility existing if disconnection of the drive voltage is caused to feed a reverse braking voltage to the motor, which is interrupted when the pulse train supplied to the microprocessor indicating rotation has substantially completely ceased, a solution as disclosed in WO 97/43821.
  • a circular saw including two adjacently located saw blades rotating in opposed directions has been described above, but it is obvious that the method according to the present invention in no way is restricted to this example of use.
  • the method according to the present invention can thus advantageously be used for other electrically driven hand tools, such as, for example, drilling machines, grinding machines, compass saws and circular saws, as well as stationary machines of different types, and electrically driven feeding devices and other devices which are made subject to varying loads during use, which could result in overload for utilized drive motor.
  • electrically driven hand tools such as, for example, drilling machines, grinding machines, compass saws and circular saws, as well as stationary machines of different types, and electrically driven feeding devices and other devices which are made subject to varying loads during use, which could result in overload for utilized drive motor.
  • the method according to the present invention makes it thus possible to obtain complete security against overload and thereby caused damage to an electric drive motor with associated components, and secures also that a start operation is performed in a controlled fashion, as well as that a start operation is interrupted in case that rotation is not obtained within a predetermined time period as from voltage feed to the motor is established.
  • start operation shown in Fig. 1 may, for example, include any desired number of steps, and supplied voltage feed can be interrupted already after one "time period 1" in Fig. 2.
  • time period 1" and “time period 2" can also be increased by a further time period or further time periods, provided that the motor used can accept this without any damage.

Landscapes

  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Control Of Electric Motors In General (AREA)
  • Control Of Ac Motors In General (AREA)
  • Control Of Stepping Motors (AREA)

Abstract

Procédé et dispositif servant à commander un électromoteur conçu pour servir de source d'entraînement pour des outils électriques manuels ou des machines fixes soumis à des charges variables pendant leur fonctionnement. Ce procédé consiste à déterminer des valeurs limites, au moyen d'expérimentations et/ou de calculs, relatives à l'alimentation en courant par rapport à différentes vitesses de rotation, à les mémoriser dans un ou plusieurs circuits à mémoire et à les comparer à la vitesse de rotation et à l'alimentation électrique réelles et actuelles au moyen d'un microprocesseur. On utilise un signal de sortie du microprocesseur afin de régler l'alimentation électrique dans des limites prédéterminées pour chaque vitesse de rotation, de manière à corriger des décélérations de la vitesse de rotation sous l'effet de l'augmentation de la charge et des accélérations de la vitesse de rotation sous l'effet de la diminution de la charge. Des valeurs limites mémorisées de dépassement et de soupassement pendant une durée prédéterminée établies pour chaque groupe de valeurs limites sont conçues pour provoquer la coupure de la tension de commande alimentant l'électromoteur. De plus, l'opération de démarrage comprend, de préférence, deux ou plusieurs étapes pendant lesquelles le microprocesseur accroît progressivement l'alimentation électrique et effectue une comparaison entre l'information transmise au microprocesseur et concernant la vitesse de rotation obtenue, et l'information mémorisée relative à la vitesse de rotation estimée pour chaque étape. Une vitesse de rotation inférieure à l'information mémorisée concernant la vitesse pendant une durée prédéterminée provoque la coupure de la tension de commande alimentant l'électromoteur.
EP99951350A 1998-09-27 1999-09-23 Procede et dispositif servant a commander un electromoteur Withdrawn EP1153473A1 (fr)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
SE9803290A SE513981C2 (sv) 1998-09-27 1998-09-27 Sätt och anordning för att styra en elmotor
SE9803290 1998-09-27
PCT/SE1999/001678 WO2000019594A1 (fr) 1998-09-27 1999-09-23 Procede et dispositif servant a commander un electromoteur

Publications (1)

Publication Number Publication Date
EP1153473A1 true EP1153473A1 (fr) 2001-11-14

Family

ID=20412749

Family Applications (1)

Application Number Title Priority Date Filing Date
EP99951350A Withdrawn EP1153473A1 (fr) 1998-09-27 1999-09-23 Procede et dispositif servant a commander un electromoteur

Country Status (4)

Country Link
EP (1) EP1153473A1 (fr)
AU (1) AU6380599A (fr)
SE (1) SE513981C2 (fr)
WO (1) WO2000019594A1 (fr)

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4387421A (en) * 1981-03-06 1983-06-07 General Electric Company Optimal and adaptive control of variable speed AC motor drives
US4580084A (en) * 1981-07-10 1986-04-01 Hitachi, Ltd. Method and system for controlling speed of electric motor
US4843297A (en) * 1984-11-13 1989-06-27 Zycron Systems, Inc. Microprocessor speed controller
JP2800570B2 (ja) * 1992-07-16 1998-09-21 日立工機株式会社 自動穿孔機
US5923145A (en) * 1997-08-15 1999-07-13 S-B Power Tool Company Controller for variable speed motor

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO0019594A1 *

Also Published As

Publication number Publication date
SE9803290L (sv) 2000-03-28
AU6380599A (en) 2000-04-17
WO2000019594A1 (fr) 2000-04-06
SE513981C2 (sv) 2000-12-04
SE9803290D0 (sv) 1998-09-27

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