CN115383664A - Electric tool and control method thereof - Google Patents

Abstract

The embodiment of the invention discloses an electric tool and a control method thereof, wherein the electric tool comprises an operation element, the operation element is used for executing the startup or shutdown of the electric tool, and the control method of the electric tool comprises the following steps: when a shutdown signal of the electric tool is detected, acquiring the current rotation direction of the motor; detecting a starting signal of the electric tool when the motor does not stop rotating in the current rotating direction, and determining a target rotating direction of the motor based on the state of the operating element; and controlling the interval duration of the starting of the motor responding to the starting signal according to the target rotating direction and the current rotating direction of the motor. Compared with the technical scheme of direct starting of the motor in the prior art, the technical scheme provided by the embodiment of the invention firstly determines whether the target rotation direction of the motor is consistent with the current rotation direction before the motor is started in response to the starting signal, so that the interval duration of starting of the motor in response to the starting signal is controlled, and the accuracy of motor reversing is improved.

Description

Electric tool and control method thereof

Technical Field

The embodiment of the invention relates to the technical field of intelligent control, in particular to an electric tool and a control method thereof.

Background

At present, a motor which adopts a semiconductor switching device to realize electronic commutation has the advantages of high reliability, no commutation spark, low mechanical noise and the like, and is widely applied to various electric tools.

In general, after the electric tool is stopped, the motor continues to rotate under the action of inertia, and when the electric tool is restarted, the phenomenon of wrong motor commutation easily occurs, so that the use effect of a user is seriously reduced.

Disclosure of Invention

The embodiment of the invention provides an electric tool and a control method thereof, which aim to solve the problem of abnormal starting of the electric tool and improve the use effect of a user.

In a first aspect, an embodiment of the present invention provides a control method for an electric tool, where the electric tool includes an operating element, and the operating element is configured to execute power on or power off of the electric tool, and the control method for the electric tool includes:

when a shutdown signal of the electric tool is detected, acquiring the current rotation direction of a motor;

detecting a start signal of the electric tool when the motor does not stop rotating in the current rotation direction, and determining a target rotation direction of the motor based on a state of the operating element;

and controlling the interval duration of the starting of the motor responding to the starting signal according to the target rotating direction and the current rotating direction of the motor.

Optionally, controlling an interval duration of the starting of the motor in response to the start signal according to the target rotation direction and the current rotation direction of the motor includes:

if the current rotating direction is the same as the target rotating direction, controlling the interval duration to be a first duration;

if the current rotating direction is opposite to the target rotating direction, controlling the interval duration to be a second duration;

wherein the first duration is less than the second duration.

Optionally, the first time duration is less than or equal to 70ms.

Optionally, if the current rotation direction is opposite to the target rotation direction, responding to the power-on signal when the rotation speed of the motor in the current rotation direction is controlled to be reduced to less than 15% of the maximum rotation speed of the motor.

Optionally, a rotational inertia and/or a current rotational speed of the motor are obtained, and the second duration is determined according to the rotational inertia and/or the current rotational speed of the motor.

In a second aspect, an embodiment of the present invention further provides an electric tool, including an operating element, configured to perform power on or power off of the electric tool; still include the controller, the controller includes:

the signal detection module is used for detecting a starting signal and a shutdown signal of the electric tool;

the direction detection module is used for acquiring the current rotation direction of a motor when a shutdown signal of the electric tool is detected, detecting a startup signal of the electric tool when the motor does not stop rotating in the current rotation direction, and determining the target rotation direction of the motor based on the action of the operation element;

and the motor control module is used for controlling the interval duration of the starting of the motor responding to the starting signal according to the target rotating direction and the current rotating direction of the motor.

Optionally, a motor driving module is further included;

the motor driving module comprises an inverter bridge, the inverter bridge comprises an upper bridge arm switching element and a lower bridge arm switching element, and a phase voltage input end of the motor is connected with the inverter bridge; the motor driving module is used for controlling the motor to brake when the signal detection module detects the shutdown signal, and controlling the motor to start when the signal detection module detects the startup signal.

Optionally, when the signal detection module detects the shutdown signal, the upper bridge arm switching element is in an off state, and the lower bridge arm switching element is in an on state.

Optionally, the system further comprises a rotor position detection module; the rotor position detection module is connected between the controller and the motor and used for detecting the rotor position of the motor when the starting signal is detected, and the controller is used for controlling the switching states of the upper bridge arm switching element and the lower bridge arm switching element according to the rotor position.

Optionally, the system further comprises a power supply and a power conversion circuit;

the power supply conversion circuit is electrically connected with the controller and used for converting the voltage output by the power supply into the voltage matched with the controller, and the power supply is used for providing electric energy for the electric tool.

According to the technical scheme provided by the embodiment of the invention, before the motor responds to the starting signal to start, whether the target rotation direction of the motor is consistent with the current rotation direction is determined, and the interval duration of the motor responding to the starting signal to start is controlled, so that the accuracy of motor reversing is improved.

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 an embodiment of the present invention;

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

fig. 4 is a schematic structural diagram of another electric tool provided in the embodiment of the invention;

fig. 5 is a schematic structural diagram of another electric tool provided in the embodiment of the invention;

fig. 6 is a schematic structural diagram of an electric tool according to an 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.

Fig. 1 is a flowchart of a control method of an electric tool according to an embodiment of the present invention, and referring to fig. 1, the method may be executed by the electric tool, and may specifically be implemented by software and/or hardware in the electric tool, and the control method of the electric tool according to the embodiment of the present invention specifically includes the following steps:

and S110, acquiring the current rotation direction of the motor when the shutdown signal of the electric tool is detected.

Specifically, the power tool includes an operating element, wherein the operating element is used for performing power on or power off of the power tool, and for example, the operating element may be a switch device such as a button or a wrench. The motor is an important component of the electric tool, the electric tool can be operated by controlling the motor to operate, and the motor can be a brushless motor. In this embodiment, the shutdown of the power tool includes a brake-off of the motor, and further includes a free-stop of the motor due to the stop of the driving. The shutdown signal may be a signal that the operating element is triggered to shut down the power tool, or may be an abnormal protection shutdown signal, such as an overcurrent protection signal. When the electric tool receives a shutdown signal, the motor performs brake or free shutdown, the motor cannot stop rotating immediately under the action of inertia, and can continue to rotate under the action of inertia within a period of time to obtain the current rotating direction of the motor, wherein the rotating direction of the motor can be obtained by a direction detection device inside the electric tool.

And S120, detecting a starting signal of the electric tool when the motor does not stop rotating in the current rotating direction, and determining the target rotating direction of the motor based on the state of the operating element.

Specifically, the starting signal may be a signal that the operating element is triggered to start the motor, and it is easily understood that the running direction of the motor includes forward rotation and reverse rotation, and the running state of the motor can be controlled by the operating element. For example, the states of the operating element may include a first state, a second state, and a third state, wherein the first state corresponds to the motor rotating in the forward direction; the second state is an intermediate state and corresponds to braking or free stop of the motor; the third state corresponds to motor reversal.

In this embodiment, the initial state of the motor may be a shutdown state, or may be a state when the power tool receives a shutdown signal and performs brake braking or a free shutdown in the running process (hereinafter, the description is given by taking an example that the power tool receives the shutdown signal and performs brake braking). When the initial state of the motor is the stopped state, the motor is not currently rotated, and the target rotation direction (forward rotation or reverse rotation) of the motor can be determined by the state of the operation member. When the initial state of the motor is the running state, when a shutdown signal of the electric tool is detected, the current rotating direction of the motor is obtained according to the state of the operating element, and under the action of inertia, the motor continues to rotate in a decelerating manner according to the current rotating direction. During the deceleration of the motor (the motor does not completely stop rotating in the current rotation direction), when the power-on signal is detected again, the target rotation direction of the motor is determined according to the current state of the operating element.

And S130, controlling the interval duration of the starting of the motor responding to the starting signal according to the target rotating direction and the current rotating direction of the motor.

Specifically, in order to ensure the accuracy of the commutation when the motor is started, when the electric tool receives a start signal, the motor is started in response to the start signal after a period of time, and the period of time may be determined according to whether the target rotation direction of the motor is matched with the current rotation direction. Illustratively, when the motor receives a shutdown signal in the operation process, the current operation direction of the motor is detected to be a forward rotation direction, and the motor continues to rotate forward until the motor is completely stopped under the action of inertia. In the process that the motor receives the shutdown signal to perform brake braking, if the motor is rotated again, namely the motor is controlled to be started through the operation element, the motor receives the startup signal again, the target rotation direction of the motor is determined based on the current state of the operation element, and whether the target rotation direction is consistent with the current rotation direction or not is determined, so that the length of the interval time for starting the motor in response to the startup signal is controlled, and the accuracy of motor reversing is ensured.

According to the control method of the electric tool provided by the embodiment of the invention, when the power-off signal of the electric tool is detected, the current rotating direction of the motor is obtained based on the previous state of the operating element, and when the power-on signal of the electric tool is detected again in the motor braking process, the target rotating direction of the motor is determined based on the current state of the operating element, and the interval duration of the motor starting in response to the power-on signal is controlled according to the target rotating direction and the current rotating direction of the motor. Compared with the technical scheme of direct starting of the motor in the prior art, the technical scheme provided by the embodiment of the invention determines whether the target rotation direction of the motor is consistent with the current rotation direction before the motor is started in response to the starting signal, so that the interval duration of starting of the motor in response to the starting signal is controlled, and the accuracy of motor reversing is improved.

Fig. 2 is a flowchart of a control method of an electric tool according to an embodiment of the present invention, and referring to fig. 2, based on the foregoing technical solution, the control method of an electric tool according to an embodiment of the present invention includes:

s210, when a shutdown signal of the electric tool is detected, the current rotating direction of the motor is obtained.

And S220, detecting a starting signal of the electric tool when the motor does not stop rotating in the current rotating direction, and determining the target rotating direction of the motor based on the state of the operating element.

And S230, if the current rotating direction is the same as the target rotating direction, controlling the interval duration to be a first duration.

And S240, if the current rotating direction is opposite to the target rotating direction, controlling the interval duration to be a second duration.

Specifically, the rotation direction of the motor includes a forward rotation and a reverse rotation, and when the motor is switched from one rotation state to another rotation state, if the motor cannot overcome the current inertia, the direction of the motor cannot be changed immediately after the motor is started, so that a position test error and a commutation error are easily caused. In this embodiment, when the motor is commutated during operation, the interval duration of the motor starting in response to the start signal is controlled by determining whether the current rotation direction of the motor is consistent with the target rotation direction. When the current rotating direction is the same as the target rotating direction, controlling the interval duration of the motor starting in response to the starting signal to be a first duration; and when the current rotating direction is opposite to the target rotating direction, controlling the interval duration of starting the motor in response to the starting signal to be a second duration, wherein the first duration is less than the second duration.

Illustratively, the current rotation direction of the motor is a forward rotation direction, and the motor is in a forward rotation and deceleration running state by controlling the motor to brake. If the motor is controlled to rotate forwards again by the operating element, because the starting current of the motor is small under the action of inertia, the motor can be controlled to start within a short time interval in response to the starting signal, for example, the first time interval can be less than or equal to 70ms. When the motor rotates forwards and decelerates, if the motor is controlled to rotate reversely through the operating element again, because the target rotating direction of the motor is opposite to the current rotating direction, the starting current is larger when the motor is started again, and the current torque force of the motor cannot overcome the rotating inertia of the motor, therefore, the motor needs to respond to the starting signal to start at an interval of time, the interval time is the second duration, so that the motor can be started by overcoming the current rotating inertia after the brake braking of the second duration, and the accuracy of the motor reversing is improved.

It can be understood that, when the current rotation direction of the motor is not consistent with the target rotation direction, the motor needs to overcome the rotational inertia of the motor in the current rotation direction when being started in response to the start signal, and needs a large start current, and if the start current is smaller than the brake current at that time, the motor cannot overcome the rotational inertia and immediately change the rotation direction. Therefore, when the starting signal is detected when the motor does not stop rotating in the current rotating direction, and the current rotating direction is opposite to the target rotating direction, the rotating speed of the motor in the current rotating direction is controlled to be reduced to below 15% of the maximum rotating speed of the motor, and then the starting signal is responded. That is, the magnitude of the second period of time may be determined by the rotational speed of the motor in the current rotational direction. Compared with the technical scheme that the motor can be started after the motor completely stops rotating in the prior art, the technical scheme provided by the embodiment can realize restarting without waiting for the complete stop of the motor, can save the starting time of the motor, and increases the use experience of a user.

Alternatively, in this embodiment, the second time period during which the motor is started in response to the power-on signal may be determined by obtaining the moment of inertia and/or the current rotation speed of the motor. Specifically, the moment of inertia of the motor is the moment of inertia of the rotor and a part of the mechanical structure, and the second duration may be determined by a second duration = f (moment of inertia/current rotation speed), where the second duration = f (moment of inertia/current rotation speed) is a functional relationship satisfied between the second duration and the moment of inertia and/or the current rotation speed, and for a motor with a large moment of inertia, a time required for starting the motor to rotate with a starting current of the same magnitude is longer than a time required for a motor with a small moment of inertia.

It should be noted that when the current rotation direction of the motor is consistent with the target rotation direction, the motor may be started immediately after a short time delay, that is, the first time period is short, so that the first time period is irrelevant to the rotational inertia and/or the current rotation speed of the motor.

Optionally, an embodiment of the present invention further provides an electric tool, fig. 3 is a schematic structural diagram of an electric tool according to an embodiment of the present invention, fig. 4 is a schematic structural diagram of another electric tool according to an embodiment of the present invention, and referring to fig. 3 and fig. 4, the electric tool according to an embodiment of the present invention includes an operation element S for performing power on or power off of the electric tool; the controller 10 is further included for controlling the rotation direction, the rotation speed and other relevant rotation parameters of the motor. The specific controller 10 includes: a signal detection module 11, a direction detection module 12 and a motor control module 13.

The signal detection module 11 is configured to detect a power-on signal and a power-off signal of the electric tool.

The direction detection module 12 is configured to acquire a current rotation direction of the motor 50 when a power-off signal of the electric tool is detected, and detect a power-on signal of the electric tool when the motor 50 does not stop rotating in the current rotation direction, and determine a target rotation direction of the motor 50 based on the actions of the operation element S.

And the motor control module 13 is configured to control an interval duration of the start of the motor 50 in response to the power-on signal according to the target rotation direction and the current rotation direction of the motor 50.

In the electric tool provided by the embodiment of the present invention, in the rotation process of the motor, when the motor 50 receives the shutdown signal, the direction detection module 12 obtains the current rotation direction of the motor 50 based on the previous state of the operation element S, and in the deceleration process of the motor when the motor receives the shutdown signal, when the signal detection module 11 detects the startup signal of the electric tool again, the direction detection module 12 determines the target rotation direction of the motor 50 based on the current state of the operation element, and the motor control module 13 controls the interval duration of the startup of the motor 50 in response to the startup signal according to the target rotation direction of the motor 50 and the current rotation direction. Compared with the technical scheme of direct starting of the motor in the prior art, the technical scheme provided by the embodiment of the invention determines whether the target rotation direction of the motor 50 is consistent with the current rotation direction before the motor 50 is started in response to the starting signal, so that the interval duration of starting of the motor 50 in response to the starting signal is controlled, and the accuracy of reversing of the motor 50 is improved.

Optionally, with continued reference to fig. 4, the power tool further includes a motor drive module 30; the motor driving module 30 includes an inverter bridge including an upper bridge arm switching element and a lower bridge arm switching element, and a phase voltage input terminal of the motor 50 is connected to the inverter bridge; the motor driving module 30 is configured to control the motor 50 to brake when the signal detection module 11 detects a shutdown signal, and control the motor 50 to start when the signal detection module 11 detects a startup signal.

Specifically, the power-on signal may be a signal that the operating element S is triggered to start the motor 50, and the power-off signal may be a signal that the operating element S is triggered to brake the motor 50. The motor drive module 30 includes an inverter bridge for driving the motor 50. The upper bridge arm switching elements of the inverter bridge comprise Q1, Q3 and Q5, and the lower bridge arm switching elements comprise Q2, Q4 and Q6.

The upper arm switching elements and the lower arm switching elements of the inverter bridge form a three-phase bridge, which is connected to three-phase windings a, B, and C of the motor 50, respectively. Illustratively, the upper arm switching element Q1 and the lower arm switching element Q2 form a bridge of an a-phase winding, and a voltage input end of the a-phase winding is connected to a U point (corresponding to an a-phase power supply of the inverter bridge) between the switching element Q1 and the switching element Q2; the upper bridge arm switching element Q3 and the lower bridge arm switching element Q4 form a bridge of a B-phase winding, and the voltage input end of the B-phase winding is connected to a V point (corresponding to a B-phase power supply of an inverter bridge) between the switching element Q3 and the switching element Q4; the upper arm switching element Q5 and the lower arm switching element Q6 constitute a bridge of a C-phase winding, and a voltage input end of the C-phase winding is connected to a point W (corresponding to a C-phase power supply of the inverter bridge) between the switching element Q5 and the switching element Q6. For example, it may be provided that: the A-phase power supply of the inverter bridge is connected with the A-phase winding of the motor 50, the B-phase power supply of the inverter bridge is connected with the B-phase winding of the motor 50, the C-phase power supply of the inverter bridge is connected with the C-phase winding of the motor 50, and the rotation direction of the motor 50 is positive rotation; the A-phase power supply of the inverter bridge is connected with the A-phase winding of the motor 50, the B-phase power supply of the inverter bridge is connected with the C-phase winding of the motor 50, and the C-phase power supply of the inverter bridge is connected with the B-phase winding of the motor 50, wherein the rotation direction of the motor 50 is reversed. The direction of rotation of the motor can be changed by controlling the state of the operating element S. After the direction detection module 12 determines the target rotation direction of the motor 50, the motor control module 13 controls the start interval duration of the corresponding start signal of the motor 50 according to whether the target rotation direction of the motor 50 is consistent with the current rotation direction, so as to ensure the accuracy of the commutation of the motor 50.

When the motor 50 receives the power-on signal and is started for the first time, the direction detection module 12 determines the rotation direction of the motor 50 based on the current state of the operation element S, and if the operation element S is in the first state at this time, the direction detection module 12 determines that the target rotation direction of the motor is forward rotation. Because the motor 50 is started for the first time, the motor control module 13 can directly output a control signal to the inverter bridge to control the motor 50 to rotate; it is of course also possible to control the rotation of the motor 50 after a short time delay (e.g. a first time period).

In the rotation process of the motor 50, the operation element S is controlled to be in the second state, that is, the motor 50 receives the shutdown signal, the motor control module 13 outputs a brake signal to the inverter bridge to brake the motor 50, and at this time, the direction detection module 12 determines that the current rotation direction of the motor 50 is the forward rotation (the motor 50 is in the forward rotation and deceleration state) based on the previous state of the operation element S. During the braking of the motor 50, the state of the operating element S is changed to start the motor 50 again, for example, the operating element S is controlled to be in the third state, that is, when the signal detection module 11 detects the power-on signal again (at this time, the motor 50 is still in the rotating state, and has not been stopped yet), the direction detection module 12 determines that the target rotating direction of the motor 50 is the reverse direction based on the current state of the operating element S. The motor control module 13 determines that the current rotation direction of the motor 50 is not consistent with the target rotation direction according to the signal output by the direction detection module 12, and the motor control module 13 sends a control signal to the inverter bridge after delaying for a second time period to control the motor 50 to start. If the operating element S is still in the first state, the direction detection module 12 determines that the target rotational direction of the motor 50 is forward based on the current state of the operating element S. The motor control module 13 determines that the current rotation direction of the motor 50 is consistent with the target rotation direction according to the signal output by the direction detection module 12, and the motor control module 13 sends a control signal to the inverter bridge after delaying for a first time period to control the motor 50 to start. Wherein the second duration is greater than the first duration.

It should be understood that fig. 4 merely shows an exemplary schematic configuration of the power tool and does not show the process of controlling the commutation of the motor by the operating element S. The previous state of the operating element S in the present embodiment refers to a state of the operating element S before the shutdown signal is not received by the motor 50.

In this embodiment, when the signal detection module 11 detects a shutdown signal, a control mode that the lower arm switch elements are all turned on and the upper arm switch elements are all turned off may be adopted to perform brake. For example, when the signal detection module 11 detects a shutdown signal, the motor control module 13 outputs a control signal to the motor drive module 30, controls the upper arm switching elements Q1, Q3, and Q5 of the inverter bridge to be turned off, and controls the lower arm switching elements Q2, Q4, and Q6 to be turned on, so that the three-phase winding of the motor 50 is short-circuited to perform braking, thereby enabling the motor 50 to decelerate quickly, and further facilitating reduction of a time interval for restarting the motor.

Optionally, fig. 5 is a schematic structural diagram of another electric tool provided in an embodiment of the present invention, and on the basis of the above technical solutions, referring to fig. 5, the electric tool provided in the embodiment of the present invention further includes a power supply 40 and a power conversion circuit 70; the power conversion circuit 70 is electrically connected to the controller 10, and is configured to convert a voltage output by the power supply 40 into a voltage matched with the controller 10, where the power supply 40 is configured to provide power for the power tool.

And a rotor position detection module 60 connected between the controller 10 and the motor 50, and configured to detect a rotor position of the motor 50 when a power-on signal is detected, where the controller 10 is configured to control switching states of the upper arm switching elements and the lower arm switching elements according to the rotor position.

Specifically, the power supply 40 is used for supplying power to the electric tool, and the power supply 40 may include an ac power supply used in cooperation with a rectifying and filtering module, an electromagnetic compatibility module, and the like, and may also include a dc power supply, such as a battery pack, which is detachably mounted in the electric tool. The power supply 40 is electrically connected to the motor driving module 30 through the operating element S, and the power tool can be powered on by closing the operating element S. The power supply 40 also converts the voltage output by the power supply 40 into a voltage matched by the controller 10 through the power conversion circuit 70. Fig. 5 only shows the connection relationship among the modules by way of example, and the voltage output by the power conversion circuit 70 may not only supply voltage to the motor control module 13, but also supply voltage to other modules in the power tool.

When the motor 50 is started from the stop state to the first time, the signal detection module 11 outputs a power-on signal to the direction detection module 12. After the direction detection module 12 receives the start signal, the target rotation direction of the motor 50 is determined based on the current state of the operation element S, and since the motor 50 is started for the first time and there is no current rotation direction, the motor control module 13 can directly output a control signal to the inverter bridge to control the rotation of the motor 50; it is of course also possible to control the rotation of the motor 50 after a short delay.

When the motor 50 receives a shutdown signal, the motor control module 13 controls the upper bridge arm switching elements Q1, Q3 and Q5 of the inverter bridge to be turned off, and controls the lower bridge arm switching elements Q2, Q4 and Q6 to be turned on, so that the three-phase winding of the motor 50 is short-circuited to realize braking. Under the action of inertia, the motor 50 does not stop immediately and is in a deceleration state. At this time, the direction detecting module 12 determines the current rotation direction of the motor 50 through the state before the operating element S by receiving the shutdown signal. During the deceleration of the motor 50, when the signal detection module 11 receives the power-on signal again, the direction detection module 12 determines the target rotation direction of the motor 50 again based on the current state of the operating element S, and after the direction detection module 12 determines the target rotation direction of the motor 50, the motor control module 13 controls the interval duration of the start of the corresponding power-on signal of the motor 50 according to whether the target rotation direction of the motor 50 is consistent with the current rotation direction.

Illustratively, when the motor 50 is first started, the motor control module 13 outputs six driving pulse signals to the motor driving module 30 to drive the respective switching elements, so that the conduction states of the windings of the motor 50 are AB phase conduction, AC phase conduction, BC phase conduction, BA phase conduction, CA phase conduction, and CB phase conduction, respectively, thereby achieving motor rotation. When the signal detection module 11 detects a shutdown signal, the motor control module 13 outputs a control signal to the motor driving module 30, controls the upper bridge arm switching elements Q1, Q3, and Q5 of the inverter bridge to be turned off, and controls the lower bridge arm switching elements Q2, Q4, and Q6 to be turned on, so that the three-phase winding of the motor 50 is short-circuited to perform braking. The direction detection module 12 obtains the current rotation direction of the motor 50 according to the previous state of the operating element S.

In the process of decelerating the motor 50, when the signal detection module 11 detects the start-up signal again, the direction detection module 12 obtains the target rotation direction of the motor 50 according to the state of the operation element S, the motor control module 13 determines the interval duration of the motor starting in response to the start-up signal according to the current rotation direction and the target rotation direction of the motor 50, and detects the rotor position of the motor 50 through the rotor position detection module 60, and the motor control module 13 controls the switching elements Q1 to Q6 to be switched on in pairs when the received rotor position reaches the preset interval duration (the first duration or the second duration), so as to realize the rotation of the motor 50.

In the present embodiment, the rotor position may be obtained by detecting the back electromotive force of the winding to determine the rotor position. When the direct current motor is electrically pivoted, the electromotive force induced in the armature winding is opposite to the current direction, so that the electromotive force is called counter electromotive force; the magnitude of the back emf is proportional to the speed at which the armature winding cuts the magnetic lines of force. When the start-up signal is detected, the motor control module 13 first controls the switching elements Q1 to Q6 to be turned off, and at this time, the rotor position detection module 60 detects the back electromotive force of the winding of the motor 50, so as to detect the position of the rotor of the brushless motor by using a back electromotive force method.

Of course, in other embodiments, the hall sensor may also be directly used to detect the rotor position, which is not described herein again.

In this embodiment, the electric tool may be a handheld electric tool, or may also be a garden electric tool, or a vehicle electric tool, and the electric tool includes but is not limited to the following: electric tools needing speed regulation, such as a screwdriver, an electric drill, a wrench, an angle grinder and the like, electric tools possibly used for grinding workpieces, such as a sander and the like, and a reciprocating saw, a circular saw, a curve saw and the like possibly used for cutting the workpieces; electric hammers and the like may be used as electric tools for impact use. These power tools may also be garden type tools, such as pruners, chain saws; in addition, the electric tools may be used for other purposes, such as a blender.

As an embodiment of the electric power tool, the electric power tool may be an electric wrench, fig. 6 is a schematic structural diagram of an electric power tool according to an embodiment of the present invention, and referring to fig. 6, the electric power tool includes a housing 200, a motor 50, a functional element 100, and a trigger mechanism 300. The functional element 100 is used to implement the function of an electric tool, and for an electric wrench, the functional element 100 may be a trepan fastener to tighten bolts, screws, nuts, and other threads to tighten bolts or nuts; the motor 50 is used for driving the functional element 100 to rotate, the motor 50 can directly drive the functional element 100 to rotate, or can drive the functional element 100 after being decelerated by a deceleration device, and the motor 50 can be a brushless motor; the trigger mechanism 300 can be operated and used by a user, the trigger mechanism 300 is connected with the operating element S, and the trigger mechanism 300 can be a trigger, a button and the like; the power tool may further include a power supply 40 for supplying power to the power tool, and the power supply 40 may be a battery pack detachably mounted in the power tool.

It is to be noted that the foregoing is only illustrative of the preferred embodiments of the present invention and the technical principles employed. Those skilled in the art will appreciate that the present invention is not limited to the particular embodiments described herein, and that various obvious changes, rearrangements and substitutions will now be apparent to those skilled in the art without departing from the scope of the invention. Therefore, although the present invention has been described in some detail by the above embodiments, the invention is not limited to the above embodiments, and may include other equivalent embodiments without departing from the spirit of the invention, and the scope of the invention is determined by the scope of the appended claims.

Claims (10)

1. A control method of a power tool including an operation element for performing power on or off of the power tool, comprising:

when a shutdown signal of the electric tool is detected, acquiring the current rotation direction of a motor;

detecting a start signal of the electric tool when the motor does not stop rotating in the current rotation direction, and determining a target rotation direction of the motor based on a state of the operating element;

and controlling the interval duration of the starting of the motor responding to the starting signal according to the target rotating direction and the current rotating direction of the motor.

2. The method of claim 1, wherein controlling the duration of the interval during which the motor is activated in response to the power-on signal based on the target rotational direction and the current rotational direction of the motor comprises:

if the current rotating direction is the same as the target rotating direction, controlling the interval duration to be a first duration;

if the current rotating direction is opposite to the target rotating direction, controlling the interval duration to be a second duration;

wherein the first duration is less than the second duration.

3. The control method of an electric power tool according to claim 2, wherein the first time period is less than or equal to 70ms.

4. The control method of the electric power tool according to claim 2,

and if the current rotating direction is opposite to the target rotating direction, responding to the starting signal when the rotating speed of the motor in the current rotating direction is controlled to be reduced to be less than 15% of the maximum rotating speed of the motor.

5. The control method of an electric power tool according to claim 2,

and acquiring the rotational inertia and/or the current rotating speed of the motor, and determining the second time length according to the rotational inertia and/or the current rotating speed of the motor.

6. An electric tool includes an operation element for performing power on or off of the electric tool; characterized in that, still include the controller, the controller includes:

the signal detection module is used for detecting a starting signal and a shutdown signal of the electric tool;

the direction detection module is used for acquiring the current rotation direction of a motor when a shutdown signal of the electric tool is detected, detecting a startup signal of the electric tool when the motor does not stop rotating in the current rotation direction, and determining the target rotation direction of the motor based on the action of the operation element;

and the motor control module is used for controlling the interval duration of the starting of the motor responding to the starting signal according to the target rotating direction and the current rotating direction of the motor.

7. The power tool of claim 6, further comprising a motor drive module;

the motor driving module comprises an inverter bridge, the inverter bridge comprises an upper bridge arm switching element and a lower bridge arm switching element, and a phase voltage input end of the motor is connected with the inverter bridge; the motor driving module is used for controlling the motor to brake when the signal detection module detects the shutdown signal, and controlling the motor to start when the signal detection module detects the startup signal.

8. The power tool according to claim 7, wherein when the signal detection module detects the shutdown signal, the upper arm switching element is in an off state, and the lower arm switching element is in an on state.

9. The power tool of claim 7, further comprising a rotor position detection module; the rotor position detection module is connected between the controller and the motor and used for detecting the rotor position of the motor when the starting signal is detected, and the controller is used for controlling the switching states of the upper bridge arm switching element and the lower bridge arm switching element according to the rotor position.

10. The power tool of claim 6, further comprising a power supply source and a power conversion circuit;

the power supply conversion circuit is electrically connected with the controller and used for converting the voltage output by the power supply into the voltage matched with the controller, and the power supply is used for providing electric energy for the electric tool.

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