阅读说明：本技术 电动工具控制方法及电动工具 (Electric tool control method and electric tool ) 是由 吴勇慷 段俊雅 于 2019-11-18 设计创作，主要内容包括：本发明实施例公开了一种电动工具控制方法及电动工具。该电动工具设置有无感电机和控制器,该方法包括：在电动工具启动时,若确定电动工具堵转,则输出驱动无感电机反转的第一控制信号；在向无感电机施加第一控制信号至设定时间后,输出驱动无感电机正转的第二控制信号。通过反转,电动工具齿轮箱传动机构中的齿轮间具有了一定的间隙,从而减小了无感电机的启动负载。此时,无感电机正转,无感电机在较小的启动负载下,能够快速提升转速,从而成功启动电动工具。解决了背景技术中因为无感电机负载增加出现堵转而无法启动的情况,实现在电动工具堵转时,能够顺利启动电动工具。(The embodiment of the invention discloses an electric tool control method and an electric tool. The electric tool is provided with a non-inductive motor and a controller, and the method comprises the following steps: when the electric tool is started, if the electric tool is determined to be locked, outputting a first control signal for driving the non-inductive motor to rotate reversely; and after the first control signal is applied to the non-inductive motor for a set time, outputting a second control signal for driving the non-inductive motor to rotate forwards. Through reverse rotation, certain gaps are formed among gears in the transmission mechanism of the gear box of the electric tool, so that the starting load of the non-inductive motor is reduced. At the moment, the non-inductive motor rotates forwards, and the rotating speed of the non-inductive motor can be rapidly increased under a small starting load, so that the electric tool is successfully started. The problem of among the background art because the increase of noninductive motor load appears the stifled circumstances of changeing and unable start-up is solved, realize when electric tool stifled commentaries on classics, can start electric tool smoothly.)

1. A power tool control method, characterized in that the power tool is provided with an induction-less motor and a controller, the method being applied to the controller, the method comprising:

when the electric tool is started, if the electric tool is determined to be locked, outputting a first control signal for driving the non-inductive motor to rotate reversely;

and outputting a second control signal for driving the non-inductive motor to rotate forwards after the first control signal is applied to the non-inductive motor for a set time.

2. The method of claim 1, wherein the determining that the power tool is locked-up comprises:

acquiring a commutation signal of the non-inductive motor;

and if the next commutation signal is not received within the set time threshold, determining that the electric tool is locked.

3. The method of claim 2, wherein a back emf detection circuit is connected to an input of the controller, the back emf detection circuit is configured to detect a back emf zero crossing signal of the non-inductive motor, and the obtaining a commutation signal of the non-inductive motor comprises:

acquiring a back electromotive force zero-crossing signal output by the back electromotive force detection circuit;

and determining the counter electromotive force zero-crossing signal as a commutation signal of the non-inductive motor.

4. The method of claim 2, wherein the time threshold is set based on a speed of the non-induction motor.

5. The method according to claim 1, wherein a back electromotive force detection circuit is connected to an input end of the controller, the back electromotive force detection circuit is used for detecting a back electromotive force zero-crossing signal of the non-inductive motor, and the output of the second control signal for driving the non-inductive motor to rotate forwards comprises:

acquiring a back electromotive force zero-crossing signal output by the back electromotive force detection circuit;

calculating the rotor position of the non-inductive motor according to the back electromotive force zero-crossing signal;

and outputting a second control signal for driving the non-inductive motor to rotate forwards according to the position of the rotor of the non-inductive motor.

6. The method of claim 1, wherein after determining that the power tool is stalled, the method further comprises:

and sending a power-off stop signal to a driving circuit of the electric tool, and stopping supplying power to the non-inductive motor until the non-inductive motor is stopped stably.

7. The method of claim 1, wherein after applying the first control signal to the non-induction motor for a set time, the method further comprises:

and sending a brake stop signal to a driving circuit of the electric tool so as to stop the rotor of the non-induction motor stably.

8. An electric power tool provided with a non-induction motor for driving the electric power tool and a controller for applying a control signal to the non-induction motor, the controller comprising:

the first control signal output module is used for outputting a first control signal for driving the non-inductive motor to reversely rotate if the electric tool is determined to be locked when the electric tool is started;

and the second control signal output module is used for outputting a second control signal for driving the non-inductive motor to rotate forwards after the first control signal is applied to the non-inductive motor for a set time.

9. The power tool of claim 8, wherein the controller further comprises:

the commutation signal acquisition module is used for acquiring commutation signals of the non-inductive motor;

and the locked-rotor determining module is used for determining that the electric tool is locked-rotor if the next commutation signal is not received within a set time threshold.

10. The power tool of claim 9, wherein the commutation signal acquisition module comprises:

the back electromotive force signal acquisition unit is used for acquiring a back electromotive force zero-crossing signal output by the back electromotive force detection circuit;

and the phase change signal determination unit is used for determining the counter electromotive force zero-crossing signal as the phase change signal of the non-induction motor.

Technical Field

The embodiment of the invention relates to a non-inductive motor control technology, in particular to an electric tool control method and an electric tool.

Background

Impact wrench load is great when the start-up, uses a period of back, and impact wrench's output shaft can levigate, and gear box lubricating oil carbonization for load increases when the start-up, takes place the locked rotor phenomenon easily. When the sensorless motor is locked, the problem of phase change error exists, and the impact wrench cannot be started.

Disclosure of Invention

The embodiment of the invention provides an electric tool control method and an electric tool, which are used for normally starting the electric tool when the electric tool is locked.

In a first aspect, an embodiment of the present invention provides a power tool control method, the power tool being provided with a non-inductive motor and a controller, the non-inductive motor being configured to drive the power tool, the controller being configured to apply a control signal to the non-inductive motor, the method including:

when the electric tool is started, if the electric tool is determined to be locked, outputting a first control signal for driving the non-inductive motor to rotate reversely;

and outputting a second control signal for driving the non-inductive motor to rotate forwards after the first control signal is applied to the non-inductive motor for a set time.

In a second aspect, embodiments of the present invention also provide an electric tool provided with a non-induction motor for driving the electric tool and a controller for applying a control signal to the non-induction motor, the controller including:

the first control signal output module is used for outputting a first control signal for driving the non-inductive motor to reversely rotate when the electric tool is determined to be locked;

and the second control signal output module is used for outputting a second control signal for driving the non-inductive motor to rotate forwards after the first control signal is applied to the non-inductive motor for a set time.

According to the embodiment of the invention, when the electric tool is detected to be locked, a control signal for enabling the non-inductive motor to rotate reversely is output to the non-inductive motor, so that the non-inductive motor rotates reversely for a certain time; after the rotation, certain gaps are formed among gears in the transmission mechanism of the gear box of the electric tool, so that the load of the non-inductive motor is reduced; and then a control signal for positive rotation is applied to the non-inductive motor, and at the moment, the non-inductive motor can quickly increase the rotating speed under a smaller starting load, so that the electric tool is successfully started. According to the technical scheme, the problem that the electric tool cannot be started due to the fact that the load of the non-inductive motor is increased and the stalling occurs in the background art is solved, and the electric tool can be started smoothly when the electric tool stalls.

Drawings

Fig. 1 is a flowchart of a control method for an electric tool according to an embodiment of the present invention;

fig. 2 is a flowchart of a control method of an electric tool according to a second embodiment of the present invention;

fig. 3 is a block diagram of an electric tool according to a third embodiment of the present invention;

fig. 4 is a block diagram of a controller according to a third embodiment of the present invention.

Detailed Description

The present invention will be described in further detail with reference to the accompanying drawings and examples. It is to be understood that the specific embodiments described herein are merely illustrative of the invention and are not limiting of the invention. It should be further noted that, for the convenience of description, only some of the structures related to the present invention are shown in the drawings, not all of the structures.

Example one

Fig. 1 is a flowchart of a control method for an electric tool according to an embodiment of the present invention, which is applicable to a situation that an electric tool is locked during a starting process, for example, a starting load of an impact wrench is large, and when the impact wrench is aged, the starting load is further increased, so that the impact wrench is locked, which may cause the impact wrench to start abnormally. The method may be performed by a controller of a power tool, the method comprising in particular the steps of:

and S110, when the electric tool is started, if the electric tool is determined to be locked, outputting a first control signal for driving the non-inductive motor to rotate reversely.

The electric tool locked-rotor refers to the situation that the electric tool still outputs torque when the rotating speed is zero, at the moment, the rotor of the non-inductive motor in the electric tool cannot normally rotate, but the stator winding of the non-inductive motor is continuously electrified, so that the non-inductive motor of the electric tool is easily damaged in a locked-rotor state. If the electric tool is locked up when being started, the electric tool cannot be normally started.

The non-inductive motor is a motor provided with a position sensor. When the controller determines that the electric tool is locked, the controller generates a first control signal for enabling the non-inductive motor to rotate reversely according to the phase commutation logic of the rotor of the non-inductive motor in a reverse rotating mode, and applies the first control signal to the non-inductive motor to enable the non-inductive motor to rotate reversely. The reverse rotation means that the non-induction motor rotates in the direction opposite to the working direction. By reversing the non-induction motor, the load of the electric tool can be reduced.

Optionally, this embodiment determines whether the electric tool is locked up by judging whether the commutation signal is received within a set time, and this process specifically includes:

acquiring a commutation signal of the non-inductive motor;

if the next commutation signal is not received within a set time threshold, determining that the electric tool is locked; otherwise, determining that the electric tool is not locked.

The controller applies corresponding control signals to the stator according to the current position of the rotor of the non-induction motor, and the rotor rotates from the current position to the next position. The switching of the stator of the non-inductive motor from one power-on state to another power-on state is phase change. The controller of the power tool may record the commutation time at each commutation. Thus, the controller determines whether commutation is normal by calculating the time difference between two consecutive commutations and comparing the time difference with a time threshold. For example, if the set time threshold is 50ms, if the time difference between two consecutive commutation is 45ms, that is, the next commutation signal can be received within the set time threshold, it is determined that the electric tool has no stalling; and if the phase change time difference of two consecutive times is 51ms, namely the next phase change signal is not received within the set time threshold, determining that the electric tool is locked.

The set time threshold is related to the rotating speed of the non-inductive motor, and the larger the rotating speed is, the smaller the time threshold is. Because the rotating speed of the non-inductive motor has a corresponding relation with the applied current, the rotating speed of the non-inductive motor can be determined by acquiring the current signal applied to the non-inductive motor, and the corresponding time threshold can be determined by combining the characteristic curve of the non-inductive motor. Typically, the time threshold is set to a multiple of the theoretical commutation time difference at the corresponding speed. For example, if the normal commutation time at a certain rotation speed is 2ms, the time threshold may be set to 30ms to accurately determine that the electric tool is in the locked-rotor state. Optionally, the time threshold is set to 30ms to 100 ms.

And S120, outputting a second control signal for driving the non-inductive motor to rotate forwards after the first control signal is applied to the non-inductive motor for a set time.

The positive rotation refers to that the non-inductive motor rotates according to the working steering, and the working steering of the non-inductive motor can be set by a user. And applying a second control signal to the non-inductive motor to enable the non-inductive motor to carry out phase commutation according to the forward phase commutation logic.

The setting time can be set according to factors such as the model of the non-inductive motor, the service time of the electric tool and the like, for example, the longer the service time is, the larger the setting time is; the shorter the usage time, the smaller the setting time is. The set time is usually 30 to 60 ms.

The function piece of the electric tool is driven to rotate reversely by the reverse rotation of the non-inductive motor. For example, when the electric tool is a percussion drill, the impact block of the percussion drill can move back and forth along with the non-inductive motor under the driving of the non-inductive motor, while the hammer of the percussion drill is not moved, so that the percussion drill can be driven to retreat for a certain distance by the reverse rotation of the non-inductive motor, a certain distance flows out of the percussion drill and the hammer, and a certain gap is left in the gear. At this moment, when the noninductive motor carries out forward rotation again, the loading of noninductive motor just can reduce to the noninductive motor can rotate with the higher rotational speed before the stall, realizes starting this electric tool when the stall.

After the non-inductive motor is reversely rotated by applying the first control signal, optionally, the present embodiment determines the rotor position of the non-inductive motor by using a back electromotive force zero-crossing detection method, and applies the second control signal to the non-inductive motor to drive the non-inductive motor to rotate forward. The method specifically comprises the following steps:

acquiring a back electromotive force zero-crossing signal output by the back electromotive force detection circuit;

calculating the rotor position of the non-inductive motor according to the back electromotive force zero-crossing signal;

and outputting a second control signal for driving the non-inductive motor to rotate forwards according to the position of the rotor of the non-inductive motor.

The counter electromotive force zero-crossing signal is a counter electromotive force zero-crossing signal of a suspension phase of the non-inductive motor, the rotor position of the non-inductive motor can be determined through the counter electromotive force zero-crossing signal, and the controller applies a phase change signal to the non-inductive motor according to the rotor position. Therefore, the counter electromotive force zero-crossing signal of the suspended phase corresponds to the phase change time of the non-inductive motor, so that the controller outputs a second control signal to change the phase of the non-inductive motor when detecting the counter electromotive force zero-crossing signal, and the non-inductive motor rotates normally.

The technical scheme of the embodiment is particularly suitable for the situation that the rotation blockage occurs in the starting process of the non-induction motor, for example, when the electric tool is an impact wrench, the load of the impact wrench is increased when the impact wrench is started due to carbonization of lubricating oil of a gear box caused by abrasion of an output shaft after the impact wrench is used for more than 6 months. At this time, the situation of locked-up rotation easily occurs, resulting in the failure of starting the impact wrench. At the moment, the non-inductive motor is enabled to rotate reversely by outputting the first control signal to the non-inductive motor, so that the impact wrench is driven to rotate reversely, a certain gap is reserved for a gear box of the impact wrench, the forward rotation control signal is applied to the non-inductive motor, the load of the non-inductive motor is reduced, the rotating speed is increased quickly, and the starting probability of the impact wrench is greatly improved.

The working principle of the electric tool control method is as follows: in the starting process of the non-inductive motor, if the rotation blockage of the non-inductive motor is detected, a control signal for enabling the non-inductive motor to rotate reversely is output firstly, the electric tool rotates reversely, a certain gap is reserved between gears in a gear box transmission mechanism of the electric tool after the rotation blockage, so that the load of the non-inductive motor is reduced, the control signal for rotating normally is applied to the non-inductive motor, and at the moment, the starting load of the non-inductive motor is reduced, so that the electric tool can be started smoothly.

According to the technical scheme of the embodiment, when the electric tool is detected to be locked, a control signal for enabling the non-inductive motor to rotate reversely is output to the non-inductive motor, and the non-inductive motor is enabled to rotate reversely for a certain time; after the rotation, certain gaps are formed among gears in the transmission mechanism of the gear box of the electric tool, so that the load of the non-inductive motor is reduced; and then a control signal for positive rotation is applied to the non-inductive motor, and at the moment, the non-inductive motor can quickly increase the rotating speed under a smaller starting load, so that the electric tool is successfully started. According to the technical scheme, the problem that the electric tool cannot be started due to the fact that the load of the non-inductive motor is increased and the stalling occurs in the background art is solved, and the electric tool can be started smoothly when the electric tool stalls.

Example two

Fig. 2 is a flowchart of a control method for an electric tool according to a second embodiment of the present invention, where the method for acquiring a phase change time before stalling of an electric tool is optimized based on the second embodiment of the present invention, and the method specifically includes:

s210, when the electric tool is started, acquiring a counter electromotive force zero-crossing signal output by the counter electromotive force detection circuit, and determining the counter electromotive force zero-crossing signal as a commutation signal of the non-inductive motor.

When an electric signal is applied to a stator winding of the non-inductive motor, a rotor of the non-inductive motor is driven to rotate by a magnetic field generated by the electric signal, meanwhile, the non-inductive motor rotates to generate a changing magnetic field inside the non-inductive motor, and under the action of the changing magnetic field, each phase of stator winding of the non-inductive motor induces counter electromotive force. Each time phase commutation is carried out, the counter electromotive force of the suspended phase of the stator winding of the non-inductive motor just crosses zero, namely, the counter electromotive force zero-crossing signals correspond to the phase commutation moments one by one, and therefore the counter electromotive force zero-crossing signals can be determined as the phase commutation signals of the non-inductive motor.

And S220, if the next commutation signal is not received within the set time threshold, determining that the electric tool is locked.

And S230, sending a power-off stop signal to a driving circuit of the electric tool, and stopping supplying power to the non-inductive motor until the non-inductive motor is stopped stably.

In which the time for stopping the power supply is set to 50ms, and the non-induction motor is made to be stationary, so as to prevent the inertia due to the forward rotation from affecting the reverse rotation.

And S240, after the first control signal is applied to the non-inductive motor for a set time, sending a brake stop signal to a driving circuit of the electric tool to stop the rotor of the non-inductive motor stably.

And S250, outputting a second control signal for driving the non-inductive motor to rotate forwards.

According to the technical scheme, whether the electric tool is locked up is judged by judging whether the commutation signal is received or not within the set time threshold. When the electric tool is determined to be locked, stopping supplying power to the non-inductive motor to enable the non-inductive motor to be stable, and applying a reverse control signal to the non-inductive motor to prevent the non-inductive motor from influencing reverse rotation due to the inertia of the non-inductive motor in forward rotation; after a control signal for enabling the non-inductive motor to rotate reversely is applied to the non-inductive motor for a certain time, a brake stop signal is applied to the non-inductive motor to stop the non-inductive motor stably, then the control signal for enabling the non-inductive motor to rotate forwards is applied to the non-inductive motor, and the non-inductive motor is started. The motor is stopped by applying the control signals before the reverse rotation and the forward rotation, so that the influence of the rotary inertia of the previous state on the current rotary state is eliminated, and the starting probability of the non-inductive motor is further improved.

EXAMPLE III

Fig. 3 is a block diagram of a power tool according to a third embodiment of the present invention, the power tool is provided with a non-inductive motor 320 and a controller 310, the non-inductive motor 320 is used for driving the power tool, and the controller 310 is used for applying a control signal to the non-inductive motor 320. The power tool further includes a back electromotive force detection circuit 340, and the back electromotive force detection circuit 340 is configured to detect a back electromotive force zero-crossing signal of the non-induction motor 320. The controller 310 determines a phase-change signal of the non-inductive motor according to the output result of the back electromotive force detection circuit 340, and further outputs a corresponding control signal to the driving circuit 330, and the non-inductive motor 310 is driven to rotate by the driving circuit 330.

Fig. 4 is a block diagram of a controller according to a third embodiment of the present invention, where the controller 310 specifically includes: a first control signal output module 311 and a second control signal output module 312, wherein,

the first control signal output module 311 is configured to, when the electric tool is started, output a first control signal for driving the non-inductive motor to rotate reversely if it is determined that the electric tool is locked;

and a second control signal output module 312, configured to output a second control signal for driving the non-inductive motor to rotate forward after the first control signal is applied to the non-inductive motor for a set time.

Optionally, the controller further comprises:

the commutation signal acquisition module is used for acquiring commutation signals of the non-inductive motor;

and the locked-rotor determining module is used for determining that the electric tool is locked-rotor if the next commutation signal is not received within a set time threshold.

Optionally, an input end of the controller is connected to the back electromotive force detection circuit 340, the back electromotive force detection circuit 340 is configured to detect a back electromotive force of the non-inductive motor, and the phase-change signal obtaining module specifically includes:

the first back electromotive force signal acquisition unit is used for acquiring a back electromotive force zero-crossing signal output by the back electromotive force detection circuit;

and the phase change signal determination unit is used for determining the counter electromotive force zero-crossing signal as the phase change signal of the non-induction motor.

In the commutation signal acquisition module, a time threshold is set according to the rotating speed of the non-inductive motor.

Optionally, the second control signal output module 312 specifically includes:

the second back electromotive force signal acquisition unit is used for acquiring a back electromotive force zero-crossing signal output by the back electromotive force detection circuit;

and the second control signal output unit is used for outputting a second control signal for driving the non-inductive motor to rotate forwards when the back electromotive force zero-crossing signal is acquired.

On the basis of the above technical solution, optionally, the controller further includes:

and the shutdown protection module is used for sending a power-off shutdown signal to a drive circuit of the electric tool and stopping supplying power to the non-inductive motor until the non-inductive motor is stopped stably.

On the basis of the above technical solution, optionally, the controller further includes:

and the brake stopping module is used for sending a brake stopping signal to a driving circuit of the electric tool so as to stop the rotor of the non-induction motor stably.

The electric tool provided by the embodiment of the invention can execute the electric tool control method provided by the embodiment of the invention, and has the corresponding functional modules and beneficial effects of the execution method. Reference may be made to the description in the method embodiments of the invention for details not explicitly described in this embodiment.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. 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, although the present invention has been described in greater detail by the above embodiments, the present invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the present invention, and the scope of the present invention is determined by the scope of the appended claims.