EP4341048A1 - Procédé de commande pour freiner un moteur électrique - Google Patents

Procédé de commande pour freiner un moteur électrique

Info

Publication number
EP4341048A1
EP4341048A1 EP22727879.3A EP22727879A EP4341048A1 EP 4341048 A1 EP4341048 A1 EP 4341048A1 EP 22727879 A EP22727879 A EP 22727879A EP 4341048 A1 EP4341048 A1 EP 4341048A1
Authority
EP
European Patent Office
Prior art keywords
electric motor
rotor
current
semiconductor component
winding
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.)
Pending
Application number
EP22727879.3A
Other languages
German (de)
English (en)
Inventor
Christian Augustin
Xiaodong Zhang
Walter Wissmach
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.)
Hilti AG
Original Assignee
Hilti AG
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 Hilti AG filed Critical Hilti AG
Publication of EP4341048A1 publication Critical patent/EP4341048A1/fr
Pending 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
    • H02P25/00—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details
    • H02P25/02—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the kind of motor
    • H02P25/10—Commutator motors, e.g. repulsion motors
    • H02P25/14—Universal motors
    • 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
    • H02P3/00—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters
    • H02P3/06—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter
    • H02P3/08—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter for stopping or slowing a dc motor
    • H02P3/10—Arrangements for stopping or slowing electric motors, generators, or dynamo-electric converters for stopping or slowing an individual dynamo-electric motor or dynamo-electric converter for stopping or slowing a dc motor by reversal of supply connections
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for

Definitions

  • the present invention relates to a control method for braking an electric motor, a control method for controlling an electric drive unit, and a computer program product.
  • a drilling tool of an electric hand-held power tool such as a drill
  • a mechanical safety device in the form of a slipping clutch is conventionally installed in the drill so that the drill does not rotate around its own axis when it is wedged and an operator of the drill is possibly injured. This separates the drive from the drilling tool, the power supply to the electric motor is switched off and the electric motor runs down without endangering the operator. If an electronic protective device is to take over this function, high braking currents are required to carry out this process in a few milliseconds, so that the safety of the operator is guaranteed.
  • the voltage at the rotor winding is reversed, for example in electric motors.
  • the polarity reversal in an electric motor is conventionally performed by using a bridge circuit with TRIACs (bidirectional thyristor triodes) which is operated with an AC voltage.
  • TRIACs bidirectional thyristor triodes
  • the polarity reversal can only take place during a zero crossing of the alternating current, since TRIACs can only then change their state, in particular switch off. This can result in a delay of up to 10 ms (with a period of a mains half-wave of 50 Hz) during the braking process.
  • one object of the present invention is to propose an improved control method for an electric hand-held power tool.
  • a control method for braking an electric motor of an electric handheld power tool includes a stator winding and a rotor winding.
  • the electric motor is switched from motor operation to braking operation.
  • an input voltage applied to the rotor winding is reversed compared to motor operation.
  • a rotor current of the rotor winding is limited as a function of a predetermined threshold value.
  • a stator current of the stator winding is regulated as a function of a current speed of the electric motor.
  • This method has the advantage that when the electric motor is being braked, the rotor current and the stator current of the electric motor can be set precisely and independently of one another.
  • the rotor current can advantageously be limited to a predetermined current level and the stator current can be regulated independently of this, so that it is possible to brake the electric motor within a predetermined period of time, but with a high braking torque, in a way that protects the carbon brushes.
  • the limited rotor current and the adjustable stator current due to the limited rotor current and the adjustable stator current, brush fire and the heating of the electric motor can be reduced. As a result, the carbon brush wear of the electric motor can be reduced. This leads to longer maintenance intervals for the electric motor and thus to an increased service life of the electric motor of the electric hand-held power tool.
  • the electric motor comprises an electric motor with brushes, preferably a universal motor or an all-current motor.
  • the electric hand-held power tool is designed, for example, as a drill, a hammer drill, a saw, a mixer, a grinder, a cut-off grinder or the like.
  • the electric hand tool can be operated in particular with a cable.
  • the electric handheld power tool can have a receiving bay for receiving a rechargeable battery, which supplies it with energy.
  • the electric motor includes in particular a stator with at least the stator winding and a rotor with at least the rotor winding.
  • the stator winding can be referred to as a field winding of the electric motor, while the rotor winding can be referred to as an armature winding of the electric motor.
  • the stator winding has an ohmic resistance and an inductance
  • the rotor winding also has an ohmic resistance and an inductance.
  • the respective ohmic resistance is preferably as small as possible.
  • a work process such as drilling into a subsurface or a chiseling process, is preferably carried out by an operator of the electric hand-held power tool.
  • the electric motor in particular, and thus also a tool driven by it, is brought to a standstill.
  • the term “braking operation” is to be understood as meaning that the electric motor is not in motor operation.
  • the braking operation can also include time intervals in which the electric motor is not braked with a braking torque and can include time intervals in which a current flow through the electric motor has a driving effect. In particular, this can be the case for a short time interval directly after the switchover from motor operation to braking operation.
  • the rotor current is preferably limited as a function of the predetermined threshold value in such a way that the absolute value of the rotor current is less than or equal to the predetermined threshold value, ie does not exceed the predetermined threshold value.
  • Equation (1) L Armature is the inductance of the rotor winding and u LArmature is the rotor voltage across the rotor winding.
  • equation (2) applies to the rotor voltage u LArmature :
  • U L Armature U m ⁇ U R Armature U IND , Equation (2)
  • U in is the input voltage across the rotor winding
  • U RArmature is a voltage drop across the ohmic resistance of the rotor
  • U IND is a voltage induced across the rotor winding, which can be represented by equation (3):
  • the magnetic excitation flux x E is provided in particular in such a way that the rotating rotor moves in the magnetic excitation flux y E .
  • the magnetic excitation flux y E can also be referred to as the magnetic field of the stator winding, which is caused by the flow of the stator current through the stator winding.
  • the electric motor is preferably completely disconnected from an energy source.
  • the second step is carried out as soon as the rotor current reaches or falls below a predetermined switching threshold value.
  • the predetermined switching threshold value is 0 A.
  • the rotor current When the rotor current has reached the predetermined switching threshold value in particular, the rotor current has decayed completely, and is therefore preferably 0 A.
  • the second step further comprises: connecting the rotor winding in parallel with the stator winding.
  • the parallel connection preferably takes place before the polarity reversal.
  • the stator and rotor windings of the electric motor are connected as in a series-wound machine, whereas after the parallel connection, the stator and rotor windings of the electric motor are connected as in a shunt-wound machine.
  • the fourth step includes: increasing the stator current as a function of the rotor current and/or the current speed of the electric motor.
  • the stator current is increased in particular with a drop in the current speed.
  • the braking torque can be increased by increasing the stator current.
  • the fourth step is carried out after a predetermined period of time has elapsed after the second step has been carried out.
  • the second step waits for the predetermined period of time to expire.
  • the predetermined period of time is less than 5 ms, preferably less than 4 ms, preferably less than 3 ms, preferably less than 2 ms.
  • the stator winding is preferably energized and the stator current can increase.
  • the stator current can be controlled independently of the rotor current. This measure advantageously reduces brush sparking, as a result of which carbon brush wear is reduced.
  • control method includes: detecting a predetermined operating state of the electric hand tool during motor operation of the electric motor, and braking the electric hand tool according to the first to fourth steps when the predetermined operating state is detected.
  • the predetermined operating state includes at least one operating interruption state, in particular a jamming of a drilling tool of the electric hand-held power tool.
  • the drilling tool becomes wedged in a substrate, such as reinforcement in a reinforced concrete block, during a drilling process with the electric hand-held power tool, this is recorded as an operational interruption state.
  • the electric motor is then braked as described above.
  • control method also includes: detecting the predetermined operating state by means of a sensor, in particular by means of a gyro sensor, of the electric hand-held power tool.
  • a computer program product which comprises instructions which, when the program is executed by a computer, cause the latter to execute the control method according to the first aspect.
  • a computer program product such as a computer program means
  • a server in a network, for example, as a storage medium such as a memory card, USB stick, CD-ROM, DVD, or in the form of a downloadable file. This can be done, for example, in a wireless communication network by transferring a corresponding file with the computer program product or the computer program means.
  • a control method for controlling an electric drive unit for an electric handheld power tool includes an electric motor with a stator winding and a rotor winding, a control circuit for controlling the electric motor and a connection unit for coupling a power source to drive the electric motor.
  • the stator winding is connected via a first node to a stator-side first half-bridge comprising a first semiconductor component and a second semiconductor component, and is connected to the rotor winding via a second node.
  • the rotor winding is connected to a third node, which is connected to the connection unit via a conductive component.
  • the control circuit includes a third semiconductor component, which is connected to the rotor winding and the stator winding via the second node and is connected directly to the connection unit via a fourth node.
  • the control method according to the third aspect has four steps:
  • the first semiconductor component is placed in a non-conductive state to switch the electric motor from motor operation to braking operation.
  • the first semiconductor component and the third semiconductor component are put into a conductive state for reversing the polarity of an input voltage present at the rotor winding compared to motor operation.
  • the first semiconductor component is switched to a non-conductive state as a function of a predetermined threshold value for a rotor current through the rotor winding in order to limit the rotor current.
  • the first semiconductor component is alternately placed in a conductive state and in a non-conductive state in order to regulate a stator current through the stator winding as a function of a current speed of the electric motor.
  • the targeted control of the respective semiconductor components of the electric drive unit according to the control method according to the third aspect has the advantage that during a braking process of the electric motor, the rotor and stator currents of the electric motor can be set precisely and independently of one another.
  • the rotor current can advantageously be limited to a predetermined current level and the stator current can be regulated independently of this, so that it is possible to brake the electric motor within a predetermined period of time, but with a high braking torque, in a way that protects the carbon brushes.
  • the limited rotor current and the adjustable stator current due to the limited rotor current and the adjustable stator current, brush fire and the heating of the electric motor can be reduced. As a result, the carbon brush wear of the electric motor can be reduced. This leads to longer maintenance intervals for the electric motor and thus to an increased service life of the electric motor of the electric hand-held power tool.
  • a further advantage of this control method is that the respective semiconductor components can be switched to a conductive state or to a non-conductive state at any point in time during engine operation and/or during braking operation. Thus, in motor operation, if the drilling tool jams, the braking operation can be initiated immediately. This increases the safety for an operator of the electric hand tool.
  • An advantage of the electric drive unit is that the control circuit of the electric drive unit has a small number of semiconductor components, in particular in comparison with conventional drive units. As a result, the production costs can be reduced, while the reliability of the electrical drive unit is increased due to the small number of semiconductor components.
  • the respective semiconductor device When the respective semiconductor device is placed in a conductive state, a current can flow through the semiconductor device. If the respective semiconductor device is placed in a non-conductive state, no current can flow through the semiconductor device.
  • the electric motor is preferably switched over from motor operation to braking operation, and a supply current flow is thereby interrupted.
  • the supply current flow is preferably not interrupted as part of a control of the first semiconductor component with a PWM signal, as is used, for example, in motor operation.
  • the period of time during which the supply current flow is interrupted is in particular many times greater than a period of the PWM signal.
  • the period of the PWM signal comprises at least one pulse (high level) and one zero pulse (low level).
  • the duty cycle preferably indicates the ratio of the pulse duration or the pulse of the PWM signal to the period duration of the PWM signal.
  • the pulse duration (high level) with a duty cycle of 0.550% is the period duration.
  • the remaining 50% of the period includes the zero pulse (low level). This means that with a PWM signal that has a duty cycle of 0.5 and a period of 100 ps, the PWM signal has a pulse or a high signal for a period of 50 ps. outputs level, and outputs a zero pulse or low level for a period of 50 ps.
  • a control connection of the respective semiconductor component is driven in particular by means of the high level of the PWM signal or the low level of the PWM signal.
  • the control connection is in the form of a base connection.
  • the control connection is in the form of a gate connection.
  • the electric drive unit comprises an electric motor comprising a stator winding and a rotor winding, a control circuit for controlling the electric motor and a connection unit for coupling an energy source for driving the electric motor.
  • the stator winding is connected via a first node to a stator-side first half-bridge comprising a first semiconductor component and a second semiconductor component, and is connected to the rotor winding via a second node.
  • the control circuit includes a third semiconductor component, which is connected to the rotor winding and the stator winding via the second node and is connected directly to the connection unit via a fourth node.
  • the rotor winding is connected to a third node, which is connected to the connection unit via a fourth semiconductor component.
  • the control circuit also has a fifth semiconductor component which is connected to the rotor winding via the third node and which is connected directly to the connection unit via a fifth node.
  • the control method according to the fourth aspect has four steps:
  • the first and/or the fourth semiconductor component is switched to a non-conductive state in order to switch the electric motor from motor operation to braking operation.
  • the third semiconductor component and the fifth semiconductor component are placed in a conductive state for reversing an input voltage applied to the rotor winding compared to motor operation.
  • the fourth semiconductor component and the fifth semiconductor component are alternately put into a conductive state and into a non-conductive state depending on a predetermined threshold value for a rotor current through the rotor winding in order to limit the rotor current.
  • the first semiconductor component is alternately placed in a conductive state and in a non-conductive state in order to regulate a stator current through the stator winding as a function of a current speed of the electric motor.
  • the targeted control of the respective semiconductor components of the electric drive unit according to the control method according to the fourth aspect has the advantage that during a braking process of the electric motor, the rotor and stator currents of the electric motor can be set precisely and independently of one another.
  • the rotor current can advantageously be limited to a predetermined current level and the stator current can be regulated independently of this, so that it is possible to brake the electric motor within a predetermined period of time, but with a high braking torque, in a way that protects the carbon brushes.
  • the limited rotor current and the adjustable stator current due to the limited rotor current and the adjustable stator current, brush fire and the heating of the electric motor can be reduced. As a result, the carbon brush wear of the electric motor can be reduced. This leads to longer maintenance intervals for the electric motor and thus to an increased service life of the electric motor of the electric hand-held power tool.
  • a further advantage of this control method is that the respective semiconductor components can be switched to a conductive state or to a non-conductive state at any point in time during engine operation and/or during braking operation. Thus, in motor operation, if the drilling tool jams, the braking operation can be initiated immediately. This increases the safety for an operator of the electric hand tool.
  • alternately opposite means in particular that two semiconductor components, such as the fourth and the fifth semiconductor component, are switched alternately in such a way that, for example, the fourth semiconductor component in is in a conductive state while at the same time the fifth semiconductor component is in a non-conductive state, or vice versa.
  • the first, second, third, fourth and/or fifth semiconductor component is designed as a bipolar transistor, in particular as an IGBT, or as a MOSFET.
  • An IGBT is a bipolar transistor with an insulated gate electrode.
  • a protective diode (freewheeling diode) is arranged in parallel with the respective semiconductor component in the blocking direction with respect to a supply current of the energy source. Freewheeling diodes are preferably used to protect against overvoltage when switching off an inductive direct voltage load, such as an electric motor.
  • the respective semiconductor component is in the form of a bipolar transistor, the freewheeling diode is connected in parallel with the collector connection and the emitter connection of the bipolar transistor.
  • the respective semiconductor component is formed as a MOSFET, the freewheeling diode is connected in parallel to the drain connection and the source connection of the MOSFET. For example, a respective rotor or stator current can decay via a respective freewheeling diode.
  • the second semiconductor component is preferably in the form of a passive component, such as a diode. This simplifies the design of the drive circuit and reduces the manufacturing complexity compared to an active component such as a bipolar transistor or a MOSFET. Furthermore, the third semiconductor component can be in the form of a thyristor. This also reduces the production costs.
  • the electric drive unit preferably has at least a first current measuring unit for determining the rotor current and a second current measuring unit for determining the stator current.
  • the electric drive unit is operated by means of a DC voltage source, a pulsating DC voltage source or an AC voltage source with a rectifier.
  • the energy source is preferably an AC voltage source with a rectifier, in which case a smoothing capacitor can also be provided.
  • the drive circuit comprises a plurality of driver circuits, with each semiconductor component being assigned a driver circuit for outputting a respective control signal for driving the respective semiconductor component.
  • the respective control signal is in particular a PWM (pulse width modulation) signal.
  • FIG. 1 shows a schematic view of an electric hand-held power tool
  • Fig. 2A is a schematic view of a first embodiment of a
  • FIG. 2B shows a schematic current flow diagram during motor operation of an electric motor within the circuit topology of the electric drive unit according to FIG. 2A;
  • FIG. 2C shows a schematic current flow diagram during braking operation of an electric motor within the circuit topology of the electric drive unit according to FIG. 2A;
  • Fig. 3A is a schematic view of a second embodiment of a
  • FIG. 3B shows a schematic current flow diagram during motor operation of an electric motor within the circuit topology of the electric drive unit according to FIG. 3A;
  • FIG. 3C shows a schematic current flow diagram during braking operation of an electric motor within the circuit topology of the electric drive unit according to FIG. 3A; 4 shows a schematic diagram of a sequence of a control method for braking an electric motor, and
  • FIG. 5 shows a schematic block diagram of a control method for braking an electric motor.
  • FIG. 1 shows a schematic view of an electric handheld power tool 1 , which is embodied as a drill, for example.
  • the drill 1 has a tool holder 3 in which a drill is used as a drilling tool 5 .
  • a primary drive of the drill 1 is an electric motor 7 with a stator winding 12 and a rotor winding 14.
  • An operator can guide the drill 1 using a handle 9 and start it up using a button 11.
  • the drilling machine 1 rotates the drill 5 continuously about a working axis and can thereby drill the drill 5 into a substrate along the working axis.
  • the drill 1 has an electric drive unit 100 in FIG. 1 .
  • the electric drive unit 100 comprises the electric motor 7 and a control circuit 4 for controlling the electric motor 7.
  • the electric drive unit 100 is coupled via an electric line arrangement 13 to a connection terminal 15, which can be coupled to a power grid (not shown) by means of a plug 17.
  • the drill 1 can also be supplied with electricity via an accumulator (not shown).
  • the drive train includes, for example, a drive shaft and a gearbox between the electric motor 7 and the drive shaft.
  • the transmission can, for example, adjust a speed n(t) (see FIG. 4) of the electric motor 7 to a desired speed of the drill 5 .
  • FIG. 2A shows a schematic view of a first embodiment of a circuit topology of an electric drive unit 100 which can be used, for example, in the electric hand-held power tool 1 according to FIG. 1 .
  • the electric drive unit 100 of FIG. 2A has an electric motor 7 which includes a stator winding 12 and a rotor winding 14 .
  • the electric drive unit 100 also has a control circuit 4 for controlling the electric motor 7 .
  • points the electric drive unit 100 has a connection unit 6, 8 for coupling an energy source 2 for driving the electric motor 7.
  • the energy source 2 is embodied as an example of an AC voltage source with a rectifier 19 . It is also possible, in particular, for the energy source 2 to be designed as a direct voltage source or as a pulsating direct voltage source.
  • the stator winding 12 is connected via a first node 10 to a first half-bridge on the stator side, which includes a first semiconductor component T1 and a second semiconductor component T2 .
  • the stator winding 12 is connected to the rotor winding 14 via a second node 16 .
  • the rotor winding 14 is connected to a third node 18, which is connected to a second connection 8 of the connection unit 6, 8 via a conductive component T6.
  • the energy source 2 has in particular a first pole, preferably a positive pole, which is connected to a first connection 6 of the connection unit 6 , 8 .
  • the energy source 2 includes a second pole, in particular a negative pole, which is connected to the second connection 8 of the connection unit 6 , 8 .
  • the control circuit 4 includes a third semiconductor component T3, which is connected via the second node 16 to the rotor winding 14 and the stator winding 12 and which is connected via a fourth node 20 directly to the second connection 8 of the connection unit 6, 8.
  • the first and third semiconductor components T1, T3 have a respective parallel-connected freewheeling diode T1D, T3D.
  • the second semiconductor component T2 is in the form of a diode.
  • An anode connection of the diode is connected to the second connection 8 of the connection unit 6 , 8 .
  • the diode is thus arranged in particular in the reverse direction to a supply current of the energy source 2 .
  • the first and the third semiconductor component T1 , T3 are each formed as an IGBT by way of example.
  • FIG. 2B shows a schematic current flow diagram of a supply current that is generated in the energy source 2 when an electric motor 7 is operating as a motor within the circuit topology of the electric drive unit 100 according to FIG. 2A.
  • the conductive component T4 is permanently in a conductive state and the third semiconductor component T3 is permanently in a non-conductive state, so that the stator winding 12 is connected in series with the rotor winding 14 .
  • the electric motor 7 is operated here as a series machine.
  • the level of the supply current through the stator and rotor windings 12, 14 and thus also the current speed n(t) see Fig.
  • connection unit 6 by the arrows A, from the energy source 2 via a first connection 6 of the connection unit 6, 8 and via a fifth node 22 through the first semiconductor component T1 from the first semiconductor device T1 via a first node 10 through the stator winding 12, from the stator winding 12 via a second node 16 through the rotor winding 14 to a third node 18, from the third node 18 through the conductive device T4 via a fourth node 20 and via a second connection 8 of the connection unit 6, 8 back to the energy source 2.
  • the fifth node 22 is connected to the first connection 6 of the connection unit 6, 8.
  • the fourth node 22 is connected to the second connection 8 of the connection unit 6, 8.
  • FIG. 2C shows a schematic current flow diagram during braking operation of an electric motor 7 within the circuit topology of the electric drive unit 100 according to FIG. 2A.
  • the respective semiconductor components are controlled as follows:
  • the first semiconductor component T1 is placed in a non-conductive state for switching the electric motor 7 from motor operation to braking operation. By putting the first semiconductor component T1 into a non-conductive state, the supply current flow is interrupted.
  • the third semiconductor component T3 is brought into a conductive state in order to connect the rotor winding 14 in parallel with the stator winding 12 .
  • the first semiconductor component T1 is switched to a conductive state in order to provide a magnetic flux, so that a voltage is induced at the rotor winding 14, which is opposite in direction to a voltage present at the rotor winding 14 during motor operation of the electric motor 7 having.
  • the first semiconductor component T1 is put into a non-conductive state depending on a predetermined threshold value k (see Fig. 4) for a rotor current I R (t) (see Fig. 4) through the rotor winding 14 to the rotor current l R (t) to limit.
  • the rotor current I R (t) is preferably limited to a predetermined threshold value.
  • a current measuring unit (not shown) is provided for this purpose, which is set up to monitor the rotor current I R (t).
  • the first semiconductor component T1 is alternately placed in a conductive state and in a non-conductive state in order to generate a stator current ls(t) (see FIG.
  • stator current Is(t) is preferably regulated to a speed-dependent value.
  • a further current measuring unit (not shown) is provided for this purpose, which is set up to monitor the stator current k(t).
  • the third semiconductor component T3 in particular is permanently in a conductive state.
  • the electric motor 7 is therefore operated as a shunt machine and no longer as a series machine (see Figure 2B).
  • the voltage induced in the rotor winding 14 in particular during braking operation is preferably caused by a rotor current I R (t) induced in the rotor winding 14 according to Lenz's law. Since this current flow is directed in such a way that the magnetic field caused by it counteracts its cause, a braking torque is created that counteracts the rotation of the rotor. Thus, the electric motor 7 is braked.
  • a supply current flows from the energy source 2 via a first connection 6 of the connection unit 6, 8 and via a fifth node 22 through the first semiconductor component T1, from the first semiconductor component T1 a first node 10 through the stator winding 12, from the stator winding 12 via a second node 16 through the third semiconductor component T3, from the third semiconductor component T3 via a fourth node 20 and via a second connection 8 of the connection unit 6, 8 back to the energy source 2.
  • an induced current flows in the rotor winding 14, which is shown by the arrows B in FIG. 2C.
  • the induced current has a direction opposite to the supply current.
  • This reverse current flows from the second node 16 through the third semiconductor device T3 to a fourth node 20, from the fourth node 20 through the conductive device T4 to a third node 18, and from the third node 18 through the rotor winding 14 back to the second node 16
  • FIG. 3A shows a schematic view of a second specific embodiment of a circuit topology of an electric drive unit 100 that can be used, for example, in the electric hand-held power tool 1 according to FIG. 1 .
  • the electric drive unit 100 of FIG. 3A has a similar structure to the electric drive unit 100 of FIG. 2A. Only the differences from the electric drive unit 100 of FIG. 2A are explained below.
  • the electric drive unit 100 of FIG. 3A has a fifth semiconductor component T5. This is designed, for example, as an IGBT with a freewheeling diode T5D connected in parallel with it. That The fifth semiconductor component T5 is connected to the rotor winding 14 via a third node 18 and is connected directly to a first connection 6 of the connection unit 6, 8 via a fifth node 22.
  • 3A is embodied as a fourth semiconductor component T4 and also, for example, as an IGBT with a freewheeling diode T4D connected in parallel therewith.
  • the second semiconductor component T2 in FIG. 3 is also in the form of an IGBT with a freewheeling diode T2D connected in parallel therewith.
  • FIG. 3B shows a schematic current flow diagram of a supply current during motor operation of an electric motor 7 within the circuit topology of the electric drive unit 100 according to FIG. 3A.
  • the feed current flow in motor operation in FIG. 3B is identical to the feed current flow in motor operation in FIG. 2B , so the explanation is omitted here.
  • the fourth semiconductor component T4 is permanently in a conductive state in this case.
  • the second and fifth semiconductor components T2, T5 are permanently in a non-conductive state during motor operation.
  • FIG. 3C shows a schematic current flow diagram during braking operation of an electric motor 7 within the circuit topology of the electric drive unit 100 according to FIG. 3A.
  • the respective semiconductor components are controlled as follows:
  • the first and/or the fourth semiconductor component T1, T4 is switched to a non-conductive state in order to switch the electric motor 7 from motor operation to braking operation.
  • the third semiconductor component T3 and the fifth semiconductor component T5 are put into a conductive state for reversing the polarity of an input voltage present at the rotor winding 14 compared to motor operation.
  • the fourth semiconductor component T4 and the fifth semiconductor component T5 are alternately inversely conductive depending on a predetermined threshold value k (see Fig. 4) for a rotor current I R (t) (see Fig. 4) through the rotor winding 14 and placed in a non-conductive state to limit rotor current I R (t).
  • the rotor current I R (t) is preferably limited to a predetermined threshold value.
  • a current measuring unit (not shown) is provided for this purpose, which is set up to monitor the rotor current I R (t).
  • the fourth and the fifth semiconductor component T4, T5 form, in particular, a second half-bridge on the rotor side.
  • the first semiconductor component T1 is alternately placed in a conductive state and in a non-conductive state in order to generate a stator current ls(t) (see FIG. 4) through the stator winding 12 as a function of a current speed n(t) ( see Fig. 4) of the electric motor 7 to regulate.
  • the stator current ls(t) is preferably set to one speed-dependent value regulated.
  • a further current measuring unit (not shown) is provided for this purpose, which is set up to monitor the stator current I R (t).
  • the third semiconductor component T3 in particular is permanently in a conductive state.
  • the electric motor 7 is therefore operated as a shunt machine and no longer as a series machine (see Fig. 3B).
  • the regulation of the stator current Is(t) through the stator winding 12 takes place (as in the drive case) in particular through the stator-side first half-bridge comprising the first and the second semiconductor component T1, T2.
  • the rotor current I R (t) through the rotor winding 14 is regulated by the second half-bridge on the rotor side, comprising the fourth and fifth semiconductor components T4, T5.
  • a voltage induced at the rotor winding 14 is preferably caused by a rotor current k(t) induced in the rotor winding 14 in accordance with Lenz's law during braking operation.
  • the induced rotor current k(t) in the rotor winding 14 is caused in particular by the polarity reversal (see above, second step) of the input voltage at the rotor winding 14 . Since this current flow is directed in such a way that the magnetic field caused by it counteracts its cause, a braking torque is created that counteracts the rotation of the rotor. Thus, the electric motor 7 is braked.
  • a supply current flows, as shown by the arrows A in FIG first semiconductor component T1 via a first node 10 through the stator winding 12, from the stator winding 12 via a second node 16 through the third semiconductor component T3, from the third semiconductor component T3 via a fourth node 20 and via a second connection 8 of the connection unit 6, 8 to the energy source 2.
  • the supply current flows from the energy source 2 via the first connection 6 of the connection unit 6, 8 via the fifth node 22 through the fifth semiconductor component T5 to a third node 18.
  • the supply current now flows in the opposite direction through the rotor winding ng (compared to motor operation).
  • a current is induced in the rotor winding 14, which flows in the same direction, so that the two currents add up in terms of amount.
  • the induced current flows from the third node 18 through the rotor winding 14 to the second node 16.
  • FIGS. 3A-3C if, for example, the feed current through the first half-bridge on the stator side becomes too high, the first semiconductor component T1 becomes one non-conductive state and put the second semiconductor component T2 in a conductive state so that the supply current can decay through the latter. If, on the other hand, the current through the second half-bridge on the rotor side, which is composed in particular of the supply current and the induced current, becomes too high, the fifth semiconductor component T5 is switched to a non-conductive state and the fourth semiconductor component T4 is switched to a conductive state. so that the current can decay over the latter.
  • Fig. 4 shows a schematic diagram of a sequence of a control method for braking an electric motor 7 (see Fig. 1, 2A, 2B, 2C, 3A, 3B, 3C), for example an electric motor 7 of the electric hand tool 1 according to Fig. 1.
  • the schematic The diagram in FIG. 4 includes three graphs 51, 52 and 53.
  • a first graph 51 shows the course of the current speed n of the electric motor 7 (vertical axis) as a function of time t (horizontal axis).
  • a second graph 52 shows the progression of the rotor current IR in the electric motor 7 (vertical axis) as a function of time t (horizontal axis).
  • a third graph 53 shows the progression of the stator current I s in the electric motor 7 (vertical axis) as a function of time t (horizontal axis).
  • the electric hand tool 1 is in motor mode (time interval between to and h).
  • a rotor current I R (t) flows through a rotor winding 14 (see FIGS. 1, 2A, 2B, 2C, 3A, 3B, 3C) as a function of a setpoint speed of electric motor 7 and a stator current ls(t) (see third graph 53, time interval between to and h) through a stator winding 12 (see FIGS. 1, 2A, 2B, 2C, 3A, 3B, 3C) as a function of the setpoint speed of the electric motor 7.
  • the drilling tool 5 (see Fig. 1) of the electric hand machine tool 1 wedges in a rebar during motor operation when working with the electric hand machine tool 1, this is detected by a sensor, such as a gyro sensor, as an operational interruption state of the electric hand machine tool 1.
  • a sensor such as a gyro sensor
  • the operation interruption state is detected, in which the electric motor 7 is switched over from a motor operation to a braking operation.
  • a supply current flow through the stator winding 12 and/or the rotor winding 14 is interrupted.
  • the rotor current I R (t) is awaited to decay, which takes place in a few milliseconds, for example.
  • the rotor current I R (t) is considered to have decayed when it reaches or falls below a predetermined switching threshold value.
  • a predetermined switching threshold value 0 A is reached at time t2 (see second graph 52).
  • An input voltage at the rotor winding 14 is then reversed in polarity, for example.
  • the rotor current I R (t) flows in the opposite direction (compared to the time interval between to and ti) and increases.
  • the rotor current I R (t) of the rotor winding 14 is then limited as a function of a predetermined threshold value k (see second graph 52).
  • the rotor current is limited or regulated to a constant value or a value that is variable over time, in particular a value that is dependent on the rotational speed.
  • the boundary is rendered conductive by means of alternately putting a fourth semiconductor device T4 (see Figures 3A, 3B, 3C) and a fifth semiconductor device T5 (see Figures 3A, 3B, 3C) in the opposite direction and into a non-conducting state in dependence on the predetermined threshold value k for the rotor current (t).
  • the system waits, for example, for a predetermined period of time to elapse (time interval between t2 and t ß ).
  • the predetermined period of time is in particular up to 2 ms or up to 3 ms. It should be noted that waiting this period is not mandatory.
  • the first semiconductor device T 1 (see FIGS. 2A, 2B, 2C, 3A, 3B, 3C) is both in the embodiment of FIGS. 2A, 2B and 2C and in the embodiment of FIGS. 3A, 3B and 3C preferably in a non-conductive state.
  • the stator current ls(t) is increased by the stator winding 12 as a function of the current speed n(t) of the electric motor 7, in particular with a drop in the current speed n(t). This occurs in the time interval between the times tz and U in the third graph 53 of FIG. 4. This advantageously results in an increase in the braking torque with which the rotor is braked.
  • the first semiconductor component T1 remains in a non-conductive state.
  • the stator winding 12 remains without current and therefore does not increase with the rotor current (t), which increases after the polarity reversal due to the polarity reversal.
  • the predetermined period of time which is, for example, up to 2 ms or up to 3 ms, the first semiconductor component T1 is switched to a conductive state.
  • the stator winding 12 is energized and can be increased in a controlled manner with a drop in the current speed n(t) of the electric motor 7, for example (see the time interval between the times tz and U in the third graph 53 of FIG. 4).
  • This measure allows the rotor current and the stator current I R (t), I s (t) of the electric motor 7 to be set independently of one another.
  • Fig. 5 shows a schematic block diagram of a control method for braking an electric motor 7 (see Fig .1, 2A, 2B, 2C, 3A, 3B, 3C), for example the electric motor 7 of the electric hand tool 1 according to Fig. 1.
  • the electric motor 7 comprises a stator winding 12 (see Figures 2A, 2B, 2C, 3A, 3B, 3C) and a rotor winding 14 (see Figures 2A, 2B, 2C, 3A, 3B, 3C).
  • the control method in Fig. 5 has four steps S1 - S4. In a first step S1, the electric motor 7 is switched from motor operation to braking operation (see FIG. 4, point in time ti). In a second step S2, an input voltage applied to the rotor winding 14 is reversed in polarity compared to motor operation (see FIG. 4, point in time t2). In a third step S3, a rotor current l R (t) (see Fig.
  • a stator current ls(t) (see Fig. 4) of the stator winding 12 is regulated as a function of a current speed n(t) (see Fig. 4) of the electric motor 7 (see the time interval between the times tz and U in the third graph 53 of Figure 4).
  • the electric motor 7 is preferably completely disconnected from the energy source 2 . For example, all semiconductor components are switched to the non-conductive state for this purpose.
  • the control method is carried out, for example, when a predetermined operating state of electric handheld power tool 1 is detected during motor operation of electric motor 7 . If this predetermined operating state has been detected, steps S1 to S4 are carried out.
  • S1 - S4 method steps t time to point in time ti time t2 time t3 time t 4 time T1 semiconductor component T1D freewheeling diode T2 semiconductor component T2D freewheeling diode T3 semiconductor component T3D freewheeling diode T4 conductive component T4D freewheeling diode T5 semiconductor component T5D freewheeling diode

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

Abstract

L'invention concerne un procédé de commande permettant de freiner un moteur électrique (7) d'une machine-outil électrique portative (1), le moteur électrique (7) comprenant un enroulement de stator (12) et un enroulement de rotor (14), le procédé comprenant les étapes consistant à : a) faire passer (S1) le moteur électrique (7) d'un mode de fonctionnement moteur à un mode de freinage ; b) inverser la polarité (S2) d'une tension d'entrée appliquée à l'enroulement de rotor (14) vis-à-vis du mode de fonctionnement moteur ; c) limiter (S3) un courant de rotor (IR(1)) de l'enroulement de rotor (14) en fonction d'une valeur seuil prédéterminée (lL) ; et d) réguler (S4) un courant de stator (ls(t)) de l'enroulement de stator (12) en fonction d'une vitesse de rotation courante (n(t)) du moteur électrique (7).
EP22727879.3A 2021-05-17 2022-05-05 Procédé de commande pour freiner un moteur électrique Pending EP4341048A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP21174114.5A EP4092905A1 (fr) 2021-05-17 2021-05-17 Procédé de commande destiné au freinage d'un moteur électrique
PCT/EP2022/062219 WO2022243058A1 (fr) 2021-05-17 2022-05-05 Procédé de commande pour freiner un moteur électrique

Publications (1)

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EP4341048A1 true EP4341048A1 (fr) 2024-03-27

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EP21174114.5A Withdrawn EP4092905A1 (fr) 2021-05-17 2021-05-17 Procédé de commande destiné au freinage d'un moteur électrique
EP22727879.3A Pending EP4341048A1 (fr) 2021-05-17 2022-05-05 Procédé de commande pour freiner un moteur électrique

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Application Number Title Priority Date Filing Date
EP21174114.5A Withdrawn EP4092905A1 (fr) 2021-05-17 2021-05-17 Procédé de commande destiné au freinage d'un moteur électrique

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US (1) US20240213894A1 (fr)
EP (2) EP4092905A1 (fr)
CN (1) CN117098633A (fr)
WO (1) WO2022243058A1 (fr)

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4333294A1 (de) * 1993-09-30 1995-04-06 Bosch Gmbh Robert Elektromotor mit elektrodynamischer Bremse
DE102014223036A1 (de) * 2014-11-12 2016-05-12 Robert Bosch Gmbh Werkzeug und verfahren zur behandlung eines werkstücks mit einem werkzeugelement eines werkzeugs

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EP4092905A1 (fr) 2022-11-23
WO2022243058A1 (fr) 2022-11-24
CN117098633A (zh) 2023-11-21
US20240213894A1 (en) 2024-06-27

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