CN118117945A - Electric tool and control method thereof - Google Patents

Electric tool and control method thereof Download PDF

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Publication number
CN118117945A
CN118117945A CN202211477029.XA CN202211477029A CN118117945A CN 118117945 A CN118117945 A CN 118117945A CN 202211477029 A CN202211477029 A CN 202211477029A CN 118117945 A CN118117945 A CN 118117945A
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CN
China
Prior art keywords
locked
motor
rotor
time interval
power tool
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
CN202211477029.XA
Other languages
Chinese (zh)
Inventor
濮维涛
李腾跃
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.)
Nanjing Chervon Industry Co Ltd
Original Assignee
Nanjing Chervon Industry Co Ltd
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 Nanjing Chervon Industry Co Ltd filed Critical Nanjing Chervon Industry Co Ltd
Priority to CN202211477029.XA priority Critical patent/CN118117945A/en
Publication of CN118117945A publication Critical patent/CN118117945A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/02—Providing protection against overload without automatic interruption of supply
    • H02P29/032—Preventing damage to the motor, e.g. setting individual current limits for different drive conditions
    • 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
    • H02K—DYNAMO-ELECTRIC MACHINES
    • H02K11/00—Structural association of dynamo-electric machines with electric components or with devices for shielding, monitoring or protection
    • H02K11/30—Structural association with control circuits or drive circuits
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/02—Details of starting control
    • H02P1/022—Security devices, e.g. correct phase sequencing
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P1/00—Arrangements for starting electric motors or dynamo-electric converters
    • H02P1/02—Details of starting control
    • H02P1/04—Means for controlling progress of starting sequence in dependence upon time or upon current, speed, or other motor parameter
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P29/00—Arrangements for regulating or controlling electric motors, appropriate for both AC and DC motors
    • H02P29/02—Providing protection against overload without automatic interruption of supply
    • H02P29/024—Detecting a fault condition, e.g. short circuit, locked rotor, open circuit or loss of load

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Computer Security & Cryptography (AREA)
  • Control Of Motors That Do Not Use Commutators (AREA)

Abstract

The application discloses an electric tool and a control method thereof. The electric tool includes: a housing; a motor disposed in the housing to provide a driving force for the power tool; the controller is electrically connected with the motor and can at least control the start and stop of the motor; the controller is configured to: monitoring the locked-rotor condition of the motor; and when the motor enters a frequent locked-rotor state, reducing a locked-rotor protection threshold value of the motor started next time, wherein the locked-rotor protection threshold value is not reduced to zero. According to the scheme, the locked rotor protection threshold value of the next starting of the motor is reduced through the controller, so that the load starting capacity of the motor is reduced, the heating of the motor winding is reduced, locked rotor protection of the motor is realized, and the influence on the normal operation of the motor is avoided.

Description

Electric tool and control method thereof
Technical Field
The embodiment of the application relates to motor technology, in particular to an electric tool and a control method thereof.
Background
Electric tools (circular saw, reciprocating saw, jig saw, angle grinder, electric wood-milling, electric drill, etc.) may become stuck by external work pieces during operation, causing stalling of the motor within the electric tool. One common way of protecting against stalling is to stop the motor drive. That is, when the output end of the electric tool is stuck, the motor is stopped if a certain period of time is continued or a current threshold is reached. When the motor is stopped, the user often tries to start the electric tool again, and starting the electric tool again and again may cause the electric tool to enter a frequent locked-up state. Because the current is larger when the motor is blocked, when the larger current flows through the stator winding, the heat of the winding is accumulated, and because the motor cannot rotate, a fan on the motor cannot radiate heat for the motor, so that the heat of the stator winding can be accumulated very high when the motor is blocked continuously for many times, and the motor winding can be burnt out. When the electric tool encounters the frequent locked-rotor condition, the phenomenon that the motor and the controller are burnt out is more easy to occur.
When the electric tool is blocked, another common way is to set a larger restarting current for the motor so as to improve the carrying capacity and break through the blocking condition of the electric tool. Since the restart starting current is greater, the higher the winding heat accumulation when such a greater current flows through the stator windings, which may cause the motor windings to burn out.
Both of the above modes of coping with the locked rotor are likely to burn out the motor and the controller, thereby damaging the electric tool.
Disclosure of Invention
The embodiment of the application provides an electric tool and a control method thereof, wherein when a motor is frequently blocked, a controller is used for reducing a blocking protection threshold value when the motor is started next time so as to reduce the load starting capacity of the motor and reduce the heating of a motor winding, thereby realizing blocking protection on the motor and avoiding influencing the normal operation of the motor.
The application discloses an electric tool, comprising: a housing; a motor disposed in the housing to provide a driving force for the electric tool; the controller is electrically connected with the motor and can at least control the start and stop of the motor; the controller is configured to: monitoring the locked-rotor condition of the motor; when the motor enters a frequent locked-rotor state, the locked-rotor protection threshold value of the motor started next time is reduced, and the locked-rotor protection threshold value is not reduced to zero.
In one embodiment, the stall protection threshold comprises at least one of a current threshold, a maximum duty cycle, a commutation time threshold, or a degaussing time threshold of the motor.
In one embodiment, the controller is further configured to: counting the number of locked revolutions from the first locked revolution of the motor, and recording the number n of locked revolutions of the motor; if the number of times of locked rotor N reaches the preset number of times N, determining that the motor enters a frequent locked rotor state.
In one embodiment, the preset number of times N is greater than or equal to 3.
In one embodiment, the controller is further configured to: monitoring the locked-rotor condition of the motor in real time; acquiring a locked rotor time interval of two adjacent locked rotor; and when the locked-rotor time interval is smaller than the preset time interval, determining that the motor enters a frequent locked-rotor state.
In one embodiment, if the first stall, the second stall, and the third stall occur continuously in the motor, and the first stall occurs earlier than the second stall occurs, the second stall occurs earlier than the third stall occurs; defining the blocking time interval of the first blocking and the second blocking as a first time interval, and the blocking time interval of the second blocking and the third blocking as a second time interval; the controller is further configured to: acquiring a locked rotor time interval when every two adjacent locked rotors occur; and when the average value of the first time interval and the second time interval is smaller than the first preset time interval, determining that the motor enters a frequent locked-rotor state.
In one embodiment, if the first stall, the second stall, and the third stall occur continuously in the motor, and the first stall occurs earlier than the second stall occurs, the second stall occurs earlier than the third stall occurs; defining the blocking time interval of the first blocking and the second blocking as a first time interval, and the blocking time interval of the second blocking and the third blocking as a second time interval; the controller is further configured to: acquiring a locked rotor time interval when every two adjacent locked rotors occur; and when the first time interval and the second time interval are smaller than the second preset time interval, determining that the electric tool enters a frequent locked-rotor state.
In one embodiment, if the first stall, the second stall, and the third stall occur continuously in the motor, and the first stall occurs earlier than the second stall occurs, the second stall occurs earlier than the third stall occurs; defining the blocking time interval of the first blocking and the second blocking as a first time interval, and the blocking time interval of the second blocking and the third blocking as a second time interval; the controller is further configured to: acquiring a locked rotor time interval when every two adjacent locked rotors occur; and when the second time interval is smaller than the first time interval and the first time interval is smaller than the third preset time interval, determining that the electric tool enters a frequent locked-rotor state.
In one embodiment, the power tool is a reciprocating saw or a jigsaw.
The application also discloses a control method of the electric tool, which comprises the following steps: monitoring the locked-rotor condition of the motor in real time; judging whether the motor enters a frequent locked-rotor state or not; when the motor enters a frequent locked-rotor state, the locked-rotor protection threshold value of the motor started next time is reduced, and the locked-rotor protection threshold value is not reduced to zero.
According to the embodiment of the application, when the motor is frequently locked, the controller in the electric tool is configured to execute frequent locked protection operation, so that the locked protection threshold value of the next starting of the motor is reduced, and the locked protection threshold value is not reduced to zero. Therefore, the load starting capacity of the motor is reduced, the heating of the motor winding is reduced, the locked rotor protection of the motor is realized, and meanwhile, the influence of the direct disconnection of the motor on the normal operation of the motor is avoided.
Drawings
FIG. 1 is a schematic view of a reciprocating saw in a power tool according to an embodiment of the present application;
Fig. 2 is a control logic diagram of a controller according to an embodiment of the present application.
Detailed Description
The application is described in further detail below with reference to the drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the application 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 application are shown in the drawings.
The electric tool related to the application can be applied to electric tools such as circular saws, reciprocating saws, curve saws, angle grinders, electric wood milling, electric drills and the like. In practical operation, electric tools such as reciprocating saws, curved saws and the like are easy to generate repeated continuous locked rotations, and the current is larger during the locked rotations.
FIG. 1 is a schematic view of a reciprocating saw in a power tool according to an embodiment of the present application; as shown in fig. 1, the reciprocating saw 001 includes: a housing 100; a motor 200 provided in the housing 100 to provide a driving force for the power tool reciprocating saw 001; the controller 300 is electrically connected with the motor 200, and the controller 300 outputs PWM signals to control the start and stop of the motor 200; specifically, the power tool further includes a drive saw blade 400; when the motor 200 is operated, the power output thereof drives the saw blade 400 to reciprocate on the cutting plane 500. While the present embodiment relates to a reciprocating saw 001, it should be understood, of course, that the present application is not limited to the disclosed embodiments, but is applicable to other types of power tools, such as other power tool circular saws, sanders, drills, electric wrenches, and the like.
In this embodiment, the controller 300 is configured to: and monitoring the locked-rotor condition of the motor 200, judging whether the motor 200 enters a frequent locked-rotor state, and if so, executing frequent locked-rotor protection operation. Frequent stall protection operations include lowering the stall protection threshold for the next start of motor 200, and stall protection threshold is not lowered to zero.
It should be noted that the motor 200 in this embodiment may be a three-phase brushless motor, including a rotor with permanent magnets and electronically commutated three-phase stator windings U, V, W. The three-phase stator windings U, V, W are connected in star or angle mode; generally, when the rotor and the stator in the motor 200 are blocked or the motor with too large load cannot drive the motor to generate the locked-rotor working condition, the rated current of 5-10 times flows through the stator winding, so that the stator rapidly heats and the winding is extremely easy to burn, and the locked-rotor working condition of the motor also comprises other modes.
The motor is provided with a motor working parameter, wherein the motor working parameter is used for protecting the motor from the locked rotor; in this embodiment, the locked rotor protection threshold value of the next start of the motor is reduced, that is, by reducing the load starting capability of the motor, the overheat of the winding when the locked rotor of the motor occurs is avoided, the locked rotor protection of the motor is realized, and meanwhile, the influence of the direct disconnection of the motor on the normal operation of the motor is also avoided. The locked rotor protection threshold is not reduced to zero, so that the motor has certain driving capability, and the fan can rotate along with the motor to help the motor to dissipate heat.
The stall protection threshold includes at least one of a maximum duty cycle, a commutation time threshold, or a degaussing time threshold of the motor.
The maximum duty ratio of the motor is a pulse signal for starting the motor, and the maximum duty ratio of the motor determines the magnitude of a current signal for starting the motor; in general, when the maximum duty cycle of the motor is smaller, the current signal for starting the motor is smaller; the commutation time threshold is understood to be a commutation time threshold of a three-phase stator winding in a motor, and generally, after the commutation time threshold is reduced, the time for the actual motor commutation at the next motor start can be reduced. The degaussing time is the time difference between the rising edge of the phase voltage after commutation of the motor winding and the falling edge of the phase voltage, wherein the falling edge of the phase voltage is the falling edge which occurs for the first time after the rising edge. Specifically, the degaussing time can be calculated from the bus voltage and the phase voltage. The degaussing time threshold is related to the commutation time threshold, and when the degaussing time threshold is reduced, the actual motor commutation time of the next motor starting time can be reduced; specifically, the maximum duty ratio of the motor can be reduced, so that the starting current of the motor is reduced, and the motor winding is prevented from being quickly heated and burnt; the actual commutation time of the motor can be reduced by reducing the commutation time threshold or the degaussing time threshold, so that the heating value of the motor winding is reduced, namely, the motor is prevented from being locked by reducing the load capacity of the motor. It is understood that the locked-rotor protection threshold may be any combination of a maximum duty cycle of the motor, a commutation time threshold, and a degaussing time threshold, and the combination of the locked-rotor protection threshold is not specifically limited herein.
In one embodiment, as shown in FIG. 1, motor 200 experiences at least two consecutive stalls, motor 200 having frequent stalling conditions; the controller 300 is specifically configured to: when at least two consecutive stalls occur to the motor 200, the stall protection threshold is lowered at the next start of the motor, and the stall protection threshold is not lowered to zero.
Wherein, two continuous stalling can be understood as that the motor is not in a normal running state between the two stalling; the time interval between two continuous locked rotations can be larger or shorter; when the motor 200 is blocked continuously at least twice, the controller 300 controls to reduce the blocking protection threshold value when the motor is started next time, so that the controller is prevented from reducing the blocking protection threshold value for a plurality of times on the basis of reducing the load capacity of the motor and the heating value on the motor winding to realize blocking protection of the motor, and the logic operation capacity of the controller is saved.
In one embodiment, motor 200 experiences at least three consecutive stalls, motor 200 having frequent stalling conditions; the controller 300 is specifically configured to: when the motor 200 enters a frequent stall state, the stall protection threshold for the next start of the motor is lowered, and the stall protection threshold is not lowered to zero. Fig. 2 is a specific logic diagram of a controller according to an embodiment of the present application, and as shown in fig. 2, a specific configuration flow of the controller 300 is as follows:
S110, when the motor continuously generates at least three times of stalling, acquiring a stall time interval when every two adjacent stalling occurs.
Wherein, the motor is continuously blocked for at least three times, which can be understood as that the motor is not in a normal running state between any two times of blocked rotations; in some embodiments, whether the motor is locked or not may be determined according to the rotation speed of the motor; and when the rotating speed of the motor is greater than a preset rotating speed threshold value, determining that the motor is blocked.
S120, judging whether the motor enters a frequent locked state according to the locked time interval.
And S130, when the average value of the at least two times of locked rotor time intervals is smaller than a first preset time interval, determining that the motor enters a frequent locked rotor state.
The first preset time interval can be set as small as possible according to the frequent stalling capability of different motors.
In one embodiment, the first stall, the second stall, and the third stall occur continuously in the motor, and the first stall occurs earlier than the second stall occurs, and the second stall occurs earlier than the third stall occurs; the blocking time interval of the first blocking and the second blocking is the first time interval, and the blocking time interval of the second blocking and the third blocking is the second time interval.
In one embodiment, the controller 300 is further specifically configured to: when the first time interval and the second time interval are both smaller than the second preset time interval, it is determined that the motor 200 enters the frequent stall state.
In other embodiments, the controller 300 is further specifically configured to: when the second time interval is smaller than the first time interval and the first time interval is smaller than the third preset time interval, it is determined that the motor 200 enters the frequent locked-rotor state.
It is understood that the manner of determining frequent stalling of the motor may be determined by any combination of the above three, and the embodiment is not particularly limited to the manner of determining frequent stalling of the motor. The second preset time interval and the third preset time interval can be determined according to the bearable frequent stalling capacity of different motors, and the second preset time interval or the third preset time interval can be as small as possible; the relationship between the second preset time interval and the third preset time interval is not particularly limited because the judging standards of the frequent stalling capability of different manufacturers or different clients to different motors are different.
And S140, when the motor enters a frequent locked-rotor state, the locked-rotor protection threshold value of the motor started next time is reduced, and the locked-rotor protection threshold value is not reduced to zero.
Wherein, in the present embodiment, the controller 300 is configured to: the motor is judged to be frequently blocked in different modes, when the motor is in a frequent blocked state, a larger current flows through the stator winding, the winding is easy to burn, and the blocking protection threshold value for the next starting of the motor is reduced, and the exemplary blocking protection threshold value is at least one of the maximum duty ratio, the phase-change time threshold value and the degaussing time threshold value of the motor, so that the load starting capacity of the motor is reduced, the frequent blocking protection of the motor is realized, and the influence on the normal operation of the motor caused by directly disconnecting the motor is avoided.
The application also discloses a control method of the electric tool, which comprises the following steps: monitoring the locked-rotor condition of the motor in real time; judging whether the motor enters a frequent locked-rotor state or not; when the motor enters a frequent locked-rotor state, the locked-rotor protection threshold value of the motor started next time is reduced, and the locked-rotor protection threshold value is not reduced to zero. The specific manner of judging whether the motor enters the frequent locked-rotor state is described above, and will not be described in detail herein.
Note that the above is only a preferred embodiment of the present application and the technical principle applied. It will be understood by those skilled in the art that the present application 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 application. Therefore, while the application has been described in connection with the above embodiments, the application is not limited to the embodiments, but may be embodied in many other equivalent forms without departing from the spirit or scope of the application, which is set forth in the following claims.

Claims (10)

1. A power tool, comprising:
A housing;
a motor disposed in the housing to provide a driving force for the power tool;
the controller is electrically connected with the motor and can at least control the start and stop of the motor;
It is characterized in that the method comprises the steps of,
The controller is configured to:
monitoring the locked-rotor condition of the motor;
And when the motor enters a frequent locked-rotor state, reducing a locked-rotor protection threshold value of the motor started next time, wherein the locked-rotor protection threshold value is not reduced to zero.
2. The power tool of claim 1, wherein the power tool comprises a power tool,
The stall protection threshold includes at least one of a current threshold, a maximum duty cycle, a commutation time threshold, or a degaussing time threshold of the motor.
3. The power tool of claim 1, wherein the power tool comprises a power tool,
The controller is further configured to:
Counting the number of locked revolutions from the first locked revolution of the motor, and recording the number of locked revolutions n of the locked revolutions of the motor;
and if the number of times of blocking rotation N reaches a preset number of times N, determining that the motor enters a frequent blocking rotation state.
4. The power tool according to claim 3, wherein the preset number N is greater than or equal to 3.
5. The power tool of claim 1, wherein the power tool comprises a power tool,
The controller is further configured to:
Monitoring the locked-rotor condition of the motor in real time;
acquiring a locked rotor time interval of two adjacent locked rotor;
And when the locked-rotor time interval is smaller than a preset time interval, determining that the motor enters a frequent locked-rotor state.
6. The power tool of claim 4, wherein the power tool comprises a power tool,
If the motor continuously generates first locked rotor, second locked rotor and third locked rotor, and the time of the first locked rotor is earlier than that of the second locked rotor, the time of the second locked rotor is earlier than that of the third locked rotor;
Defining the blocking time interval of the first blocking rotation and the second blocking rotation as a first time interval, and the blocking rotation time interval of the second blocking rotation and the third blocking rotation as a second time interval;
The controller is further configured to:
Acquiring a locked rotor time interval when every two adjacent locked rotors occur;
and when the average value of the first time interval and the second time interval is smaller than a first preset time interval, determining that the motor enters a frequent locked-rotor state.
7. The power tool of claim 4, wherein the power tool comprises a power tool,
If the motor continuously generates first locked rotor, second locked rotor and third locked rotor, and the time of the first locked rotor is earlier than that of the second locked rotor, the time of the second locked rotor is earlier than that of the third locked rotor;
Defining the blocking time interval of the first blocking rotation and the second blocking rotation as a first time interval, and the blocking rotation time interval of the second blocking rotation and the third blocking rotation as a second time interval;
The controller is further configured to:
Acquiring a locked rotor time interval when every two adjacent locked rotors occur;
And when the first time interval and the second time interval are smaller than a second preset time interval, determining that the electric tool enters a frequent locked-rotor state.
8. The power tool of claim 4, wherein the power tool comprises a power tool,
If the motor continuously generates first locked rotor, second locked rotor and third locked rotor, and the time of the first locked rotor is earlier than that of the second locked rotor, the time of the second locked rotor is earlier than that of the third locked rotor;
Defining the blocking time interval of the first blocking rotation and the second blocking rotation as a first time interval, and the blocking rotation time interval of the second blocking rotation and the third blocking rotation as a second time interval;
The controller is further configured to:
Acquiring a locked rotor time interval when every two adjacent locked rotors occur;
and when the second time interval is smaller than the first time interval and the first time interval is smaller than a third preset time interval, determining that the electric tool enters a frequent locked-rotor state.
9. The power tool of any one of claims 1-8, wherein the power tool is a reciprocating saw or a jigsaw.
10. A control method of an electric tool, comprising:
monitoring the locked-rotor condition of the motor in real time;
Judging whether the motor enters a frequent locked-rotor state or not;
when the motor enters a frequent locked-rotor state, the locked-rotor protection threshold value of the motor started next time is reduced, and the locked-rotor protection threshold value is not reduced to zero.
CN202211477029.XA 2022-11-23 2022-11-23 Electric tool and control method thereof Pending CN118117945A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202211477029.XA CN118117945A (en) 2022-11-23 2022-11-23 Electric tool and control method thereof

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202211477029.XA CN118117945A (en) 2022-11-23 2022-11-23 Electric tool and control method thereof

Publications (1)

Publication Number Publication Date
CN118117945A true CN118117945A (en) 2024-05-31

Family

ID=91214190

Family Applications (1)

Application Number Title Priority Date Filing Date
CN202211477029.XA Pending CN118117945A (en) 2022-11-23 2022-11-23 Electric tool and control method thereof

Country Status (1)

Country Link
CN (1) CN118117945A (en)

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