CN115603633B - Electric tool and control method thereof - Google Patents
Electric tool and control method thereof Download PDFInfo
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- CN115603633B CN115603633B CN202110777447.XA CN202110777447A CN115603633B CN 115603633 B CN115603633 B CN 115603633B CN 202110777447 A CN202110777447 A CN 202110777447A CN 115603633 B CN115603633 B CN 115603633B
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- conduction mode
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- 238000000034 method Methods 0.000 title claims abstract description 26
- 238000004804 winding Methods 0.000 claims abstract description 102
- 230000008569 process Effects 0.000 claims abstract description 21
- 239000004065 semiconductor Substances 0.000 claims abstract description 6
- 238000001514 detection method Methods 0.000 claims description 8
- 230000009467 reduction Effects 0.000 abstract description 3
- 230000008859 change Effects 0.000 description 10
- 230000001965 increasing effect Effects 0.000 description 10
- 238000010586 diagram Methods 0.000 description 8
- 230000000737 periodic effect Effects 0.000 description 4
- 230000007547 defect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 238000003780 insertion Methods 0.000 description 2
- 230000037431 insertion Effects 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 1
- 230000003247 decreasing effect Effects 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 238000005498 polishing Methods 0.000 description 1
- 230000008707 rearrangement Effects 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 230000003313 weakening effect Effects 0.000 description 1
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Classifications
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- 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
- H02P25/16—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring
- H02P25/18—Arrangements or methods for the control of AC motors characterised by the kind of AC motor or by structural details characterised by the circuit arrangement or by the kind of wiring with arrangements for switching the windings, e.g. with mechanical switches or relays
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- 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
-
- 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
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/14—Estimation or adaptation of machine parameters, e.g. flux, current or voltage
- H02P21/18—Estimation of position or speed
-
- 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
- H02P21/00—Arrangements or methods for the control of electric machines by vector control, e.g. by control of field orientation
- H02P21/22—Current control, e.g. using a current control loop
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- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Mechanical Engineering (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
Abstract
The invention discloses an electric tool, comprising: a power supply for providing electric energy; the motor comprises a rotor and three-phase stator windings; a driving circuit having a plurality of semiconductor switching elements to switch the number of turns on of the stator winding of the motor; the controller is at least electrically connected with the driving circuit and the motor; in the working process of the motor, the stator winding is provided with a first conduction mode of commutation conduction of the two-phase winding and a second working mode of commutation conduction of the three-phase winding; the controller is configured to: in the process that the motor works in the second working mode, the switching element in the driving circuit is controlled to maintain the off state of the first preset time period and then to recover the on state so as to reduce the phase current of the stator winding. The electric tool can ensure the increase of the rotating speed of the motor at the full speed section, and can effectively reduce the rotating speed to achieve the purpose of noise reduction when needed.
Description
Technical Field
The invention relates to the field of electric tools, in particular to an electric tool and a control method thereof.
Background
For the purpose of increasing the motor rotation speed in full-speed sections, the noninductive motor generally introduces a lead angle and a spread angle in motor control so as to increase the conduction angle of a winding and improve the field weakening of the winding, thereby increasing the motor rotation speed. However, the improvement of the weak magnetic energy by adopting the lead angle and the expansion angle has better effect on the improvement of the motor rotation speed of the full-speed section. However, too high rotation speed under some working conditions can bring larger noise, and influence the user experience.
Disclosure of Invention
In order to solve the defects in the prior art, the invention aims to provide an electric tool which can ensure the increase of the rotating speed of a full-speed section of a motor and can effectively reduce the rotating speed to achieve the purpose of noise reduction when needed.
The invention adopts the following technical scheme:
a power tool, comprising: a power supply for providing electric energy; the motor comprises a rotor and three-phase stator windings; a driving circuit having a plurality of semiconductor switching elements to switch the number of turns on of a stator winding of the motor; the controller is at least electrically connected with the driving circuit and the motor; in the working process of the motor, the stator winding is provided with a first conduction mode of commutation conduction of two phase winding groups and a second working mode of commutation conduction of three phase winding groups; the controller is configured to: and in the process that the motor works in the second working mode, controlling a switching element in the driving circuit to maintain the off state of the first preset time period and then to restore the on state so as to reduce the phase current of the stator winding.
Further, the method further comprises the following steps: the rotating speed detection module is used for detecting the rotating speed of the motor; the controller is configured to: and adjusting the duration of the first preset time period according to the current rotating speed of the motor and the preset target rotating speed.
Further, the method further comprises the following steps: a current detection module for detecting a phase current of the motor, the phase current being suddenly changed when a switching element in the driving circuit is turned off; the controller is configured to: in the process that the motor works in the second working mode, a switching element in the driving circuit is controlled to enter an off state; the driving circuit is controlled to be restored to an on state from an off state before a switching element in the driving circuit enters the off state and the phase current abruptly changes to zero.
Further, the controller is configured to: when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode; detecting the commutation times of the stator winding in the working process of the first conduction mode; when the commutation frequency is greater than or equal to a frequency threshold, a second control signal is output to enable the stator winding to be switched to the second working mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
Further, the controller is configured to: when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode; after the motor is started for a second preset time period, a second control signal is output to enable the stator winding to be switched to the second working mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
Further, the controller is configured to: when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode; detecting the demagnetizing time of the motor after the stator winding is phase-changed; and when the degaussing time is greater than or equal to a time threshold, outputting a second control signal to enable the stator winding to be switched to the second working mode, and controlling the stator winding to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
Further, the controller is configured to: the conduction angle is periodically or aperiodically changed.
A power tool, comprising: a power supply for providing electric energy; the motor comprises a rotor and three-phase stator windings; a driving circuit having a plurality of semiconductor switching elements to switch the number of turns on of a stator winding of the motor; the controller is at least electrically connected with the driving circuit and the motor; in the working process of the motor, the stator winding is provided with a first conduction mode of commutation conduction of two phase winding groups and a second working mode of commutation conduction of three phase winding groups; a current detection module for detecting a phase current of the motor, the phase current being suddenly changed when a switching element in the driving circuit is turned off; the controller is configured to: in the process that the motor works in the second working mode, a switching element in the driving circuit is controlled to enter an off state; the driving circuit is controlled to be restored to an on state from an off state before a switching element in the driving circuit enters the off state and the phase current abruptly changes to zero.
Further, the controller is configured to: when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode; detecting the commutation times of the stator winding in the working process of the first conduction mode; when the commutation frequency is greater than or equal to a frequency threshold, a second control signal is output to enable the stator winding to be switched to the second working mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
Further, the controller is configured to: when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode; after the motor is started for a second preset time period, a second control signal is output to enable the stator winding to be switched to the second working mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
The invention has the advantages that: on the premise of ensuring the motor to rotate at full speed, the reduction of the motor rotation speed can be effectively controlled.
Drawings
Fig. 1 is a schematic structural diagram of an electric tool according to an embodiment of the present invention;
FIG. 2 is a block diagram of a power tool according to an embodiment of the present invention;
fig. 3 is a schematic diagram of phase inversion of a motor winding in a two-to-two conduction period according to an embodiment of the present invention;
fig. 4 is a schematic diagram of three-conduction period commutation of a motor winding according to an embodiment of the present invention;
fig. 5 is a schematic diagram of phase inversion of two-three conduction periods of a motor winding according to an embodiment of the present invention;
FIGS. 6a and 6b are schematic diagrams of periodic changes in conduction angle according to embodiments of the present invention;
FIG. 7 is a schematic illustration of the insertion of a zero vector into the motor cycle commutation shown in FIG. 4;
fig. 8 is a schematic diagram of the relationship between the phase current variation and the zero vector insertion in fig. 7.
Detailed Description
The invention is described in detail below with reference to the drawings and the specific embodiments. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting thereof. It should be further noted that, for convenience of description, only some, but not all of the structures related to the present invention are shown in the drawings.
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. The terminology used in the description of the invention herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
The electric tool applicable to the technical scheme of the invention comprises any electric tool which can adopt a brushless and non-inductive electric control mode, such as a polishing tool, an electric drill, an electric circular saw, a reciprocating saw, a miter saw and the like, and other types of electric tools can fall within the protection scope of the invention as long as the following disclosed technical scheme can be adopted.
In the embodiment of the present application, referring to fig. 1, taking an electric drill as an example, the electric power tool 100 includes at least a housing 10, a motor 11 (not shown in fig. 1) within the housing, a power source 12, a switch 13, a drill bit 14, and the like. The casing 10 houses a motor, a control circuit board and a transmission structure (not shown). The housing 10 is also formed with a grip 101 for a user to grip.
Referring to the circuit block diagram of the electric power tool shown in fig. 2, the driving system of the motor 11 may include at least a driving circuit 20, a power source 12, a controller 21, a rotation speed detecting module 22, and a current detecting module 23.
In one embodiment, the motor 11 is a brushless direct current motor (BLDC). In one embodiment, the motor 11 is a non-inductive BLDC. In one embodiment, the motor 11 is a sensed BLDC. In the present application, the brushless dc motor may be an inner rotor motor or an outer rotor motor, and the motor 11 includes at least three-phase stator windings A, B, C, where the three-phase windings may be star-shaped or delta-shaped.
In one embodiment, the power source 12 may be selected to be an ac power source, i.e., 120V or 220V ac mains may be connected through the power interface. In one embodiment, the power source 12 may alternatively be a battery pack, which may be comprised of a set of battery cells, for example, the battery cells may be connected in series in a single power branch to form a 1P battery pack. The battery pack output voltage is subjected to voltage variation by a specific power control module, such as a DC-DC module, and a power supply voltage suitable for the driving circuit 20, the motor 11, and the like is output to supply power thereto. Those skilled in the art will appreciate that the DC-DC module is a well-established circuit structure and may be selected accordingly according to the specific parameter requirements of the power tool.
The driving circuit 20 is electrically connected to the stator windings A, B, C of the motor 11 for transmitting current from the power module 21 to the stator windings A, B, C to drive the motor 10 to rotate. In one embodiment, the driving circuit 20 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, Q6. The gate terminal of each switching element is electrically connected to the controller 21 and is configured to receive a control signal from the controller 21. The drain or source of each switching element is connected to the stator winding A, B, C of the motor 11. The switching elements Q1-Q6 receive control signals from the controller 21 to change the respective conductive states, thereby changing the current applied by the power supply 12 to the stator windings A, B, C of the motor 11. In one embodiment, the drive circuit 20 may be a three-phase bridge driver circuit including six controllable semiconductor power devices (e.g., FETs, BJTs, IGBTs, etc.). It will be appreciated that the switching element may be any other type of solid state switch, such as an Insulated Gate Bipolar Transistor (IGBT), a Bipolar Junction Transistor (BJT), etc.
To drive the motor 11 shown in fig. 2 to rotate, the driving circuit 20 generally has at least six driving states, and each switching of the driving states corresponds to one commutation of the motor. As shown in fig. 3, the horizontal axis represents the commutation point of the stator over a 360 ° period, and the vertical axis represents the back emf of the three-phase winding. In fig. 3, the interval from one commutation to the next commutation of the motor is defined as the commutation interval for every 60 ° commutation of the motor. As can be seen from fig. 3, in one commutation period of 360 °, six beats of commutation exist, and all three-phase windings of the motor are conducted by 120 °, that is, the conduction angle is 120 °. The phase change mode of the stator winding shown in fig. 3 is generally called a two-phase winding phase change conduction mode, namely a two-phase conduction mode. In the two-by-two conduction mode, the weak magnetic energy of the motor stator winding is not as high as the weak magnetic accelerating effect.
In order to improve the weak magnetic capability, the conduction angle is generally increased, for example, the conduction angle is increased to be larger than 120 °. In order to increase the conduction angle, the conduction phase of the stator winding is increased by increasing the commutation frequency in a commutation period of 360 degrees. For a three-phase motor, adding a stator winding conducting phase means changing from two-phase winding commutation conduction to three-phase winding commutation conduction, i.e. switching from two-to-three conduction. Specifically, the commutation is performed every 30 ° of rotor rotation, that is, 12 beats of commutation is performed in 360 ° commutation period, so as to ensure that the conduction angle of the three-phase winding of the motor is greater than 120 °, for example, the conduction angle is 150 °. As shown in fig. 4, the stator winding is switched from two-to-three conduction every 30 ° commutation, and from three-to-two conduction at the next commutation. Comparing fig. 4 and fig. 3, it can be seen that at the 90 ° commutation point, the B-phase winding is 30 ° commutated earlier, so that the conduction angle of the B-phase winding is increased by 30 ° relative to the original conduction angle, that is, 150 °.
By increasing the conduction angle of the stator winding, the weak magnetic energy of the winding is improved as a whole, and the rotating speed of the motor can be improved in the full-speed section of the motor rotation.
It should be noted that, since the time of the current beat of the tri-conduction needs to be determined according to the time of the previous beat of the electric angle, and the first beat is not completely 60 ° when the sensorless motor is started, the reference cannot be made. That is, if the conduction angle is directly extended by switching between three and two, the control performance is unstable due to the failure to accurately switch into the three conduction mode.
In order to solve the above problem, the present application outputs the first control signal at the initial stage of motor start, and controls the motor in a conventional two-by-two conduction manner. Further, the commutation frequency of the winding of the motor 11 is monitored during the starting process, and when the commutation frequency is greater than or equal to the frequency threshold, the controller 21 outputs a second control signal to switch the stator winding of the motor to be in tri-conduction, and controls the stator winding to switch between tri-conduction and bi-conduction within a certain conduction angle. As shown in fig. 5, when the commutation frequency of the motor is 3 times or more, the BC conduction is switched to BAC conduction, and in the subsequent process, the 60 ° commutation is switched to 30 ° commutation once, and every 30 ° commutation motor is switched from two-to-three conduction or from three-to-two conduction.
In an alternative implementation manner, the controller 21 may also monitor the time of the motor started in the first conduction manner, that is, in a two-to-two conduction manner, and after the time reaches a second preset period, output a second control signal to switch the stator winding of the motor to the three-three conduction, and control the stator winding to switch between the three-three conduction and the two-to-two conduction within a certain conduction angle.
In an alternative implementation, the controller 21 may also monitor the demagnetizing time after commutation of the windings, i.e. the freewheel time after commutation, during operation of the motor in a two-by-two conduction mode. And when the degaussing time is greater than or equal to the time threshold, outputting a second control signal to enable the motor stator winding to be switched between three-conduction and two-to-two conduction in a certain conduction angle.
It can be understood that the time for switching to two-to-three conduction is determined by monitoring the commutation times of the stator winding at the initial starting stage of the motor or the starting time of the motor or the demagnetizing time after the commutation of the motor, thereby avoiding the uncertainty of the three-to-three conduction switching points and ensuring the stability of the motor control performance when the conduction angle is expanded.
It should be noted that, in the switching operation of the motor in the two-by-two or three-by-three conduction mode, the conduction angle may be changed. The controller 21 can control the periodical or aperiodic change of the conduction angle, and can control the motor rotation speed to be further increased or decreased to a certain extent by changing the conduction angle, so as to increase the flexibility of rotation speed control. In practice, the change of the conduction angle is mainly realized by changing the time or mode of the tri-conduction. As shown in fig. 6a and 6b, the conduction angle may be periodically changed within the interval of 120 ° -180 °, specifically, the period of the periodic change of the conduction angle may be set according to the number of commutation times of the motor, for example, the conduction angle is changed once every certain number of commutation times, and the specific number of commutation times may be set according to the actual requirement, for example, 6 times, 12 times, etc. It will be appreciated that the conduction angle may be increased only or may include both an increase and a decrease during a cycle. The variation of the spread angle may comprise other variation waveforms in addition to the periodic variation shown in fig. 6a and 6 b. Other non-periodic changes in conduction angle may be random or vary from operating to operating.
Specifically, the conduction angle needs to be changed in the following two cases:
first case: as shown in fig. 3, in the process of working in a mode of switching between two and three, the conduction angle of the motor is 150 degrees, and the rotating speed of the motor in the full-speed section is higher. However, under some working conditions, the motor rotation speed is too high, so that the working effect is not obviously improved, but obvious defects are brought, for example, the motor rotation speed is not required to be too high when no load exists, and the motor rotation speed is too high, so that larger noise is brought.
To solve the above problem, the controller 21 controls the switching element in the driving circuit to maintain the off state for the first preset period of time in the tri-three conduction mode, i.e. the second mode of operation, and then returns to the on state during the switching operation of the motor in the bi-tri-conduction mode. It can be understood that the switching element in the driving circuit is disconnected, so that the driving circuit generates a zero vector, and the motor cannot be connected to a power supply under the zero vector. As shown in fig. 7, there is a small period of zero vector input in the middle of each tri-conduction interval during which the motor is not energized and is maintained in rotation by freewheel alone. By adding zero vector in the conduction interval of three conduction, the conduction angle is reduced to a certain extent, so that the weak magnetic energy of the motor winding is reduced, and the motor rotating speed is also reduced. It should be noted that, the controller may control the switching element in the driving circuit shown in fig. 2 to generate the zero vector in a manner that the lower tube is fully conductive or the upper tube is fully conductive. Alternatively, the first preset time period for inserting the zero vector may be located at an intermediate position of the three conduction intervals as shown in fig. 7, and may also be located at any position of the conduction intervals, which is not limited herein.
It should be noted that, during the first preset period of time when the controller controls the driving circuit to maintain the zero vector output, the phase current of the winding may be suddenly changed, including a sudden drop or a sudden rise. As shown in fig. 8, in the process of tri-conduction of the motor winding, the controller controls the driving circuit to generate a zero vector, so that the phase current of the corresponding one-phase winding drops suddenly. Taking phase a as an example, the upper graph in fig. 8 shows the zero vector occurrence process when phase a is on; fig. 8 is a graph showing the change in the amount of power of phase a, in which the solid line shows the current change curve when no dip occurs, i.e., no zero vector is generated by the drive circuit, and the broken line shows the current abrupt change curve when a zero vector is generated. Therefore, the current detection module 23 can detect the change of the phase current of the motor, and before the phase current suddenly changes to zero, the controller 21 controls the driving circuit to end the off state generating the zero vector and return to the previous on state. It can be understood that after the driving circuit returns to the conducting state, the motor may be in a two-to-two conducting mode or in a three-to-three conducting mode.
Alternatively, the rotation speed detection module 22 may also detect the rotation speed of the motor and output the rotation speed to the controller 21. The controller 21 adjusts the duration of the first preset time period by comparing the relationship between the current rotational speed of the motor and the preset target rotational speed. That is, by directly adjusting the time at which the drive circuit generates the zero vector, the motor can be controlled to rotate at the target rotational speed.
Note that the above is only a preferred embodiment of the present invention and the technical principle applied. It will be understood by those skilled in the art that the present invention is not limited to the particular embodiments described herein, but is capable of various obvious changes, rearrangements and substitutions as will now become apparent to those skilled in the art without departing from the scope of the invention. Therefore, while the invention has been described in connection with the above embodiments, the invention is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the invention, which is set forth in the following claims.
Claims (10)
1. A power tool, comprising:
a power supply for providing electric energy;
the motor comprises a rotor and three-phase stator windings;
a driving circuit having a plurality of semiconductor switching elements to switch the number of turns on of a stator winding of the motor;
the controller is at least electrically connected with the driving circuit and the motor;
in the working process of the motor, the stator winding is provided with a first conduction mode of commutation conduction of two phase winding groups and a second conduction mode of commutation conduction of three phase winding groups;
the controller is configured to:
in the process that the motor works in the second conduction mode, a switching element in the driving circuit is controlled to maintain the disconnection state of a first preset time period at any position of each tri-conduction interval, and then the conduction state is restored to reduce the phase current of the stator winding; and adjusting the duration of the first preset time period according to the relation between the current rotating speed of the motor and the preset target rotating speed.
2. The power tool of claim 1, wherein the power tool comprises a power tool,
further comprises:
the rotating speed detection module is used for detecting the rotating speed of the motor;
the controller is configured to:
and adjusting the duration of the first preset time period according to the current rotating speed of the motor and the preset target rotating speed.
3. The power tool of claim 1, wherein the power tool comprises a power tool,
further comprises:
a current detection module for detecting a phase current of the motor, the phase current being suddenly changed when a switching element in the driving circuit is turned off;
the controller is configured to:
in the process that the motor works in the second conduction mode, a switching element in the driving circuit is controlled to enter a disconnection state;
the driving circuit is controlled to be restored to an on state from an off state before a switching element in the driving circuit enters the off state and the phase current abruptly changes to zero.
4. The power tool of claim 1, wherein the power tool comprises a power tool,
the controller is configured to:
when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode;
detecting the commutation times of the stator winding in the working process of the first conduction mode;
when the commutation frequency is greater than or equal to a frequency threshold, a second control signal is output to enable the stator winding to be switched to the second conduction mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
5. The power tool of claim 1, wherein the power tool comprises a power tool,
the controller is configured to:
when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode;
after the motor is started for a second preset time period, a second control signal is output to enable the stator winding to be switched to the second conduction mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
6. The power tool of claim 1, wherein the power tool comprises a power tool,
the controller is configured to:
when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode;
detecting the demagnetizing time of the motor after the stator winding is phase-changed;
and when the degaussing time is greater than or equal to a time threshold, outputting a second control signal to enable the stator winding to be switched to the second conduction mode, and controlling the stator winding to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
7. The power tool according to any one of claim 4, 5 or 6, wherein,
the controller is configured to:
the conduction angle is periodically or aperiodically changed.
8. A power tool, comprising:
a power supply for providing electric energy;
the motor comprises a rotor and three-phase stator windings;
a driving circuit having a plurality of semiconductor switching elements to switch the number of turns on of a stator winding of the motor;
the controller is at least electrically connected with the driving circuit and the motor;
in the working process of the motor, the stator winding is provided with a first conduction mode of commutation conduction of two phase winding groups and a second conduction mode of commutation conduction of three phase winding groups;
a current detection module for detecting a phase current of the motor, the phase current being suddenly changed when a switching element in the driving circuit is turned off;
the controller is configured to:
in the process that the motor works in the second conduction mode, a switching element in the driving circuit is controlled to enter a disconnection state;
the driving circuit is controlled to be restored to an on state from an off state before a switching element in the driving circuit enters the off state and the phase current abruptly changes to zero.
9. The power tool of claim 8, wherein the power tool comprises a power tool,
the controller is configured to:
when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode;
detecting the commutation times of the stator winding in the working process of the first conduction mode;
when the commutation frequency is greater than or equal to a frequency threshold, a second control signal is output to enable the stator winding to be switched to the second conduction mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
10. The power tool of claim 8, wherein the power tool comprises a power tool,
the controller is configured to:
when the motor is started, a first control signal is output to the driving circuit so that the stator winding works in the first conduction mode;
after the motor is started for a second preset time period, a second control signal is output to enable the stator winding to be switched to the second conduction mode, and the stator winding is controlled to be switched between the first conduction mode and the second conduction mode within a certain conduction angle.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110777447.XA CN115603633B (en) | 2021-07-09 | 2021-07-09 | Electric tool and control method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202110777447.XA CN115603633B (en) | 2021-07-09 | 2021-07-09 | Electric tool and control method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN115603633A CN115603633A (en) | 2023-01-13 |
| CN115603633B true CN115603633B (en) | 2024-01-19 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202110777447.XA Active CN115603633B (en) | 2021-07-09 | 2021-07-09 | Electric tool and control method thereof |
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| CN (1) | CN115603633B (en) |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104579043A (en) * | 2015-01-30 | 2015-04-29 | 闫朝阳 | High-frequency-link driver for brushless motor of electric automobile |
| CN109687779A (en) * | 2019-01-05 | 2019-04-26 | 天津大学 | Brushless DC motor rotor method for detecting position based on single-phase inductance detection |
| CN109713949A (en) * | 2018-12-28 | 2019-05-03 | 武汉工程大学 | A kind of suppressing method and system of torque pulsation of brushless DC motor |
| CN112413813A (en) * | 2020-11-16 | 2021-02-26 | 珠海格力电器股份有限公司 | Fault restart control method and device and air conditioning equipment |
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2021
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Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN104579043A (en) * | 2015-01-30 | 2015-04-29 | 闫朝阳 | High-frequency-link driver for brushless motor of electric automobile |
| CN109713949A (en) * | 2018-12-28 | 2019-05-03 | 武汉工程大学 | A kind of suppressing method and system of torque pulsation of brushless DC motor |
| CN109687779A (en) * | 2019-01-05 | 2019-04-26 | 天津大学 | Brushless DC motor rotor method for detecting position based on single-phase inductance detection |
| CN112413813A (en) * | 2020-11-16 | 2021-02-26 | 珠海格力电器股份有限公司 | Fault restart control method and device and air conditioning equipment |
Non-Patent Citations (1)
| Title |
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| 无位置传感器BLDCM起动控制仿真研究;孟光伟等;《防爆电机》;第49卷(第6期);第18-23页 * |
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