Classifications

• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H7/00—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions
  • H02H7/08—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors
  • H02H7/0833—Emergency protective circuit arrangements specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems, and effecting automatic switching in the event of an undesired change from normal working conditions for dynamo-electric motors for electric motors with control arrangements
  • H02H7/0844—Fail safe control, e.g. by comparing control signal and controlled current, isolating motor on commutation error
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/02—Details
  • H02H3/021—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order
  • H02H3/023—Details concerning the disconnection itself, e.g. at a particular instant, particularly at zero value of current, disconnection in a predetermined order by short-circuiting
• • H—ELECTRICITY
  • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
  • H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
  • H02H3/00—Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection ; integrated protection
  • H02H3/02—Details
  • H02H3/04—Details with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned
  • H02H3/044—Checking correct functioning of protective arrangements, e.g. by simulating a fault
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S388/00—Electricity: motor control systems
  • Y10S388/935—Specific application:
  • Y10S388/937—Hand tool

Definitions

• the invention relates to a series motor with contactless switching function interruption elements in the form of electronic switches.
• Power tools are usually driven by electric motors that are designed as series motors (universal motors) and are controlled via mechanical switches.
• electronics are becoming more and more widespread in power tools, control of power tools is becoming more common only regarded as insufficiently safe via power semiconductors, which are also used to switch the power tool on and off.
• semiconductors can alloy through (internal short circuit) and are then no longer controllable. In the case of purely electronic switches with only a single switching distance, this can result in a permanent connection between the power supply and the motor, ie the motor can no longer be switched off or starts immediately.
• the invention is therefore based on the object of providing a series motor and a method for controlling a series motor, with which, despite the absence of mechanical switching elements, safe switching on and off is only possible using electronic switches.
• a series motor in particular for a power tool, with a first electronic switch (control switch) for switching the motor on and off, with a second electronic switch (circuit breaker), which is in series with the control switch, with a monitoring circuit to monitor the function of the switch, which evaluates the voltage potential at the connection between the control switch and the circuit breaker, and with an electronic control, preferably a microprocessor, which is coupled to the two switches and the monitoring circuit and controls at least one of the switches into a blocking state if the monitoring circuit registers a malfunction of a switch.
• the fact that two electronic switches, a control switch and a circuit breaker, are connected in series enables the motor to be switched on and off safely even if one of the two switches should malfunction.
• a monitoring circuit ensures that malfunctions of both the control switch and the circuit breaker can be detected and the motor can be controlled in a safe OFF state can. Manual monitoring of the circuit is therefore not necessary. Rather, an error check is carried out automatically when the engine is switched on, and switching on is only possible if no malfunction has been determined.
• a means for bridging the switching path of the circuit breaker with a high resistance is provided in order to permit a functional test of the control switch without starting the motor.
• the motor can be started briefly during the initial functional test, provided the control switch is alloyed. Due to the high-impedance bridging of the switching path of the circuit breaker, it can first be checked safely without the risk of the motor starting in the event of a fault in the control switch.
• the means for high-resistance bridging of the switching path of the circuit breaker can have, for example, an optocoupler, which preferably has an optotriac, and which is connected in parallel with the main connections of the circuit breaker via a resistor.
• Another way of avoiding a brief motor start-up when testing the circuit breaker in the event of a control switch failure is to provide a means for monitoring rotation of the motor coupled to the controller so that in the event of a start-up of the Motors to control at least one of the two switches into a blocking state when the protective switch is actuated without actuating the control switch.
• the means for monitoring the motor rotation can be designed as a speed sensor, for example, or can monitor the motor current. In the latter case, the armature is connected in series with a shunt resistor whose voltage drop is monitored.
• the monitoring circuit has a voltage divider with two resistors connected in series, the first resistor being connected to a first pole of an auxiliary voltage and the second resistor being connected to one of the main connections of the control switch and the second pole of the auxiliary voltage, wherein the connection between the two resistors via a third resistor to the other main terminal of the control switch is connected and an output of the control is supplied as the output of the monitoring circuit.
• the object is achieved by a series motor, in particular a series motor for a power tool, with a fuse via which the armature is connected to the supply voltage via a first electronic switch (control switch) for switching the motor on and off , and with a second electronic switch (circuit breaker), which is connected in parallel to the armature and to the control switch to trigger the fuse in the event of a fault, with an electronic control, preferably a microprocessor, which is coupled to the switches, with blocking means of the circuit breaker and for testing the function of the circuit breaker in the blocked state and with a monitoring circuit which evaluates the voltage drop at the control switch and whose output signal is fed to the electronic control in order to control the circuit breaker to trigger the fuse, if the monitoring circuit registers a malfunction of the control switch.
• a series motor in particular a series motor for a power tool
• a fuse via which the armature is connected to the supply voltage via a first electronic switch (control switch) for switching the motor on and off
• a second electronic switch circuit
• the object of the invention is also completely achieved in this way.
• a transistor with an emitter and a collector is connected between the control connection and a main connection of the circuit breaker, which transistor can be controlled for a measurement of the control current of the circuit breaker for testing it, in order to prevent the fuse from being triggered when the circuit breaker is tested.
• the electronic switches are designed as triacs.
• the object of the invention is further achieved by a method for controlling a series motor, preferably a series motor for an electric tool, with the following steps:
• a functional test is first carried out in this way before the control switch is switched on to determine whether the circuit breaker is working correctly. If this is the case, the control switch is then first checked before the control switch can be switched on in order to start the motor.
• the circuit breaker is immediately switched off again, provided the voltage potential does not rise when the circuit breaker is switched on when the control switch is switched off.
• a rotation of the motor can be monitored in order to switch the motor off again immediately when the control switch is switched off and the circuit breaker is switched on, provided that a motor rotation is registered.
• the circuit breaker for testing the control switch can also be bridged with a high resistance and it can be checked whether the voltage potential at the control switch rises to the predetermined threshold value. In this way, starting of the motor when checking the control switch can be reliably avoided even in the event of a defect.
• the object of the invention is alternatively further achieved by a method for controlling a series motor, preferably a series motor for an electric tool, with the following steps:
• step (d) disable control switch control if a malfunction is determined in step (b),
• Fig. 1 shows a first embodiment of a series motor according to the invention in a simplified basic circuit
• FIG. 2 shows a preferred embodiment of a monitoring circuit suitable for the motor according to FIG. 1;
• FIG. 2a shows a graphical representation of the input voltage at resistor R 3 of the monitoring circuit according to FIG. 2 along with the assigned output voltage at PIN 1;
• FIG. 3 shows an alternative embodiment of the monitoring circuit for the motor according to FIG. 1;
• FIG. 4 shows a modification of the circuit according to FIG. 1;
• FIGS. 1 and 5 shows a further modification of the circuit according to FIGS. 1 and
• Fig. 6 shows another embodiment of the invention with a parallel circuit breaker for tripping a fuse.
• an electric motor according to the invention is shown in the form of a circuit of a series motor and is generally designated by the number 10.
• the motor 10 is fed from the two poles 24 and 26 of an AC voltage source with 230 volts.
• the motor 10 has an armature 12 which is in series with the field windings (not shown) and to which one pole 24 of the supply voltage is connected.
• the other pole of the armature 12 is connected to the other pole 26 of the supply voltage via two triacs connected in series, namely a circuit breaker 16 and a control switch 14.
• the control connections 28 and 30 of the control switch 14 and the circuit breaker 16 are connected to an electronic control 18, which is designed as a microprocessor.
• the electronic control 18 is also connected to the two poles 24 and 26 of the supply voltage source or is additionally supplied with a supply voltage by a DC voltage source (provided the voltage supply is not already integrated in the electronic control 18).
• a monitoring circuit 20 is also connected, which monitors the voltage potential between control Switches 14 and circuit breaker 16, on the one hand, and the second pole 26 of the supply voltage source, on the other hand, are monitored and their output is coupled via a line 32 to an input 22 (pin 1) of the electronic control 18.
• the electronic control 18 also takes over the functions of a soft start when the motor is switched on and speed or power control during operation by means of a phase control of the control switch 14.
• an auxiliary voltage which can be the supply voltage V cc for the electronic control 18, is connected via a voltage divider to the one main connection of the control switch 14, which is connected to the second pole 26 of the AC voltage source.
• the voltage divider consists of resistors R. and R 2 .
• the tap of the voltage divider is connected to the input 22 (pin 1) of the controller 18.
• the tap of the voltage divider is also coupled via a third resistor R 3 to the connection between control switch 14 and circuit breaker 16.
• monitoring circuit particularly simple monitoring of the voltage potential present at the control switch 14 is made possible with only three components.
• other monitoring circuits can also be used, as is known, for example, from US Pat. No. 6,236,177 B1. Such a circuit is shown in Fig. 3 and designated by the number 20 '. Because of the simpler construction, however, a monitoring circuit according to FIG. 2 is preferred.
• FIG. 4 A modified embodiment of the electric motor according to the invention is shown in FIG. 4 and is designated overall by the number 10a. Corresponding reference numerals are used here for corresponding parts and for the modifications still to be explained.
• a means 36 for high-resistance bridging of the circuit breaker 16 is additionally provided.
• This means 36 for high-resistance bridging of the circuit breaker 16 consists of an optotriac 38 which is connected via a resistor R 4 in parallel to the two main connections of the circuit breaker 16.
• the Optotriac 38 is controlled by an LED 40.
• one of the two field windings lying in series with the armature 12 is additionally indicated by the number 13.
• this first test level is OK. This check ensures that the blocking effect is checked for both the positive half-wave and the negative half-wave.
• the circuit breaker 16 is first activated via the line 30 when switching on according to FIG. 1. In this case, if the voltage applied to pin 1 fluctuates so that the threshold value limits according to FIG. 2a are exceeded, the function is OK. Otherwise, the function is disturbed. This is because there is either a defect in the control switch 14 (short circuit), or the control circuit of the control switch 14 is defective, or the monitoring circuit 20 is defective.
• the means 36 for high-resistance bridging of the circuit breaker 16 was additionally introduced in the motor 10a according to FIG. 4.
• test 1 in the uncontrolled state of the circuit breaker and the monitoring switch, voltage at pin 1 within the threshold value range
• the latter is only bridged with high impedance with the aid of the circuit 36. In this way, a functional test of the control switch 16 can be carried out without the risk that the motor will start up immediately in the event of a short circuit in the control switch 16.
• FIG. 5 As an alternative to the circuit 36 for high-resistance bridging of the control switch 16, a means for monitoring the speed of the motor, designated overall by number 10b, is shown in FIG. 5 as a further modification.
• a shunt resistor R 5 can be provided in series with the field windings 13.
• a voltage drop at the shunt resistor R s between the pole 26 of the AC voltage and the line 52 is registered, the activation of the circuit breaker 16 is interrupted immediately in order to prevent the motor from starting.
• a speed sensor 54 could be provided, which monitors the speed of the motor, as indicated by dashed lines in FIG. 5. If the speed sensor 54 receives test 2, i.e. when the protective switch 16 is activated to test the control switch 14, a signal, the activation of the protective switch 16 is interrupted immediately to prevent the electric motor from continuing to run. Otherwise, the circuit of the motor 10b corresponds to the circuit of the motor 10a.
• FIG. 6 Another embodiment of an electric motor according to the invention is shown in FIG. 6 and is designated overall by 10c.
• a fuse 56 is provided, which can be triggered via a circuit breaker 16 in the event of a fault in the control switch 14.
• the circuit breaker 16 is connected in parallel directly behind the fuse 56 to the two poles 24 and 26 of the supply voltage source.
• the voltage potential dropping across the control switch 14 is in turn monitored by a protective circuit 20, as explained above.
• the output of the monitoring circuit 20 is in turn on pin 1 of the microprocessor 18.
• a complete functional test is not possible with the circuit according to FIG. 6, since the fuse 56 would respond immediately.
• the Control circuit of the circuit breaker 16 are checked by preventing the ignition of the circuit breaker or triacs 16.
• the gate 28 of the triac 16 is connected to an output (pin 3) of the microprocessor 18 via two resistors R 6 and R 7 connected in series.
• the connection point between the two resistors R 6 , R 7 is connected via a line 62 to a measurement input (pin 4) of the microprocessor 18.
• a transistor 60 is arranged between the gate 28 of the circuit breaker 16 and the pole 26 of the supply voltage, the base of which can be controlled via an output (pin 2) of the microprocessor 18.
• the monitoring circuit 20 is first evaluated. The test is carried out as described in connection with FIGS. 2 and 2a. If an error is found here, the circuit breaker 16 is activated to trigger the fuse 56.
• the transistor 60 is driven via pin 2 of the microprocessor 18 at its base 64. Ignition of the triac 16 is thereby prevented. Firing pulses are now output via pin 3, the transistor 60 preventing the firing. The voltage between the resistors R 6 , R 7 can now be detected at pin 4 of the microprocessor 18. The output voltage at pin
• the control of the transistor 60 via the pin 2 is canceled so that the circuit breaker or triac 16 can work during operation in order to enable the fuse 56 to trip in the event of a fault in the control switch 14.
• the control switch 14 can then be turned on to turn on the engine. If the control switch 14 is no longer activated, i.e. If no more ignition pulses are output via line 30, the voltage drop across control switch 14 must rise above a predetermined threshold value. Otherwise, the control switch 14 is defective. If a defect in the control switch 14 is detected when the device is switched off, the circuit breaker 16 is controlled via pin 3 of the control circuit 18 in order to trigger the fuse 56.

Landscapes

• Control Of Electric Motors In General (AREA)
• Control Of Direct Current Motors (AREA)
• Control Of Ac Motors In General (AREA)

Applications Claiming Priority (2)

Publications (1)

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Citations (1)

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• 2004
  • 2004-04-13 DE DE102004018966.8A patent/DE102004018966B4/de not_active Expired - Fee Related
• 2005
  • 2005-03-26 EP EP05716402A patent/EP1735888A1/de not_active Withdrawn
  • 2005-03-26 JP JP2007507688A patent/JP4521779B2/ja not_active Expired - Fee Related
  • 2005-03-26 WO PCT/EP2005/003237 patent/WO2005101606A1/de active Application Filing
  • 2005-03-26 KR KR1020067021977A patent/KR101119661B1/ko not_active IP Right Cessation
  • 2005-03-26 CN CNB2005800111889A patent/CN100541961C/zh not_active Expired - Fee Related
• 2006
  • 2006-10-13 US US11/549,455 patent/US7427842B2/en not_active Expired - Fee Related

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