Electric tool and fault detection method therefor

Abstract

An electric tool. The tool comprises: a housing (11); an electric motor (12), which comprises a stator and a rotor; and a control circuit, which is configured to control the operation of the electric motor (12). The control circuit comprises a parameter measurement module (13) and a controller (17), wherein the parameter measurement module (13) is at least configured to measure the actual value of a standard parameter of the electric motor (12); and the controller (17) is configured to: on the basis of the actual value of the standard parameter, determine a first rotation speed change curve of the electric motor (12); acquire a standard value of the standard parameter, and on the basis of the standard value, determine a second rotation speed change curve of the electric motor (12); and on the basis of the first rotation speed change curve and the second rotation speed change curve, determine whether a fault occurs in the electric motor (12). Further provided is a fault detection method for an electric tool.

Description

Electric power tool and fault detection method thereof

[0001] This application claims priority to Chinese Patent Application No. 202210328193.8, filed on March 30, 2022, the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of tool equipment, for example, to an electric power tool and a fault detection method thereof. BACKGROUND

[0003] In the related art, an electric power tool monitors and controls possible faults in the working process of a motor, such as overcurrent protection or locked-rotor protection, for example. However, after the electric power tool is used for a period of time, the motor itself may have some faults, such as demagnetization of a permanent magnet or mechanical structure jamming, which will cause the motor to be unable to rotate or to have problems in the process of rotation. If such faults are not discovered in time, the motor will be further damaged in severe cases.

[0004] This section provides background information relating to the present application, which can not necessarily be prior art. SUMMARY

[0005] To solve the problems in the prior art, one purpose of the present application is to provide an electric power tool and a fault detection method capable of detecting whether a motor is faulty.

[0006] To achieve the above-mentioned purpose, the present application adopts the following technical solution:

[0007] In some embodiments, the present application provides an electric power tool, comprising: a housing; a motor comprising a stator and a rotor; a control circuit configured to control the operation of the motor; the control circuit comprising: a parameter detection module and a controller; the parameter detection module is configured to detect at least an actual value of a standard parameter of the motor; the controller is configured to: determine a first rotational speed change curve of the motor according to the actual value of the standard parameter; obtain a standard value of the standard parameter, and determine a second rotational speed change curve of the motor according to the standard value; and determine whether the motor is faulty according to the first rotational speed change curve and the second rotational speed change curve.

[0008] In some embodiments, the standard parameter comprises at least one of a resistance, an inductance, and a stator flux linkage.

[0009] In some embodiments, the standard parameters include resistance, inductance and stator flux linkage, the controller is configured to: determine actual speed and standard speed of the motor at each time according to Formula One, determine a first speed change curve according to the actual speed of the motor at each time, and determine a second speed change curve according to the standard speed of the motor at each time; Formula One is as follows: n = (θ^2-θ^1) / (△t); wherein n is the speed of the motor at the current time, θ^1 is the stator flux linkage angle of the motor at the previous time, θ^2 is the stator flux linkage angle of the motor at the current time, and △t is the time difference between the current time and the previous time.

[0010] In some embodiments, the controller is configured to: if the difference of at least one corresponding point in the first speed change curve and the second speed change curve is greater than or equal to a first set value, determine that the motor has a fault.

[0011] In some embodiments, the parameter detection module is further configured to detect the actual speed of the motor; and the controller is further configured to: determine a third speed change curve according to the actual speed, and determine whether the control circuit has a fault according to the third speed change curve and the second speed change curve.

[0012] In some embodiments, the controller is configured to: offline acquire the actual value of the standard parameter in the detection mode.

[0013] In some embodiments, the controller is configured to: online acquire the actual value of the standard parameter in the working mode.

[0014] In some embodiments, the controller is configured to: determine whether the stator of the motor has a fault according to the actual value of the resistance and the standard value of the resistance.

[0015] In some embodiments, the controller is configured to: determine whether the stator of the motor has a fault according to the actual value of the inductance and the standard value of the inductance.

[0016] In some embodiments, the controller is configured to: determine whether the rotor of the motor has a fault according to the actual value of the stator flux linkage and the standard value of the stator flux linkage.

[0017] In a second aspect, the present application provides an electric tool, comprising: a housing; a motor arranged in the housing; a control circuit configured to control operation of the motor; the control circuit comprising: a parameter detection module and a controller; the parameter detection module is configured to detect an actual value of a standard parameter of the motor and an actual rotating speed of the motor; the controller is configured to: determine a first rotating speed change curve of the motor according to the actual value of the standard parameter; obtain a standard value of the standard parameter, and determine a second rotating speed change curve of the motor according to the standard value; determine a third rotating speed change curve of the motor according to the actual rotating speed; and determine whether the motor has a fault according to the first rotating speed change curve, the second rotating speed change curve and the third rotating speed change curve.

[0018] In some embodiments, the standard parameter comprises at least one of resistance, inductance and stator flux linkage.

[0019] In some embodiments, the controller is configured to determine whether the motor has a stator fault, a rotor fault or a control circuit fault according to the first rotating speed change curve, the second rotating speed change curve and the third rotating speed change curve.

[0020] In some embodiments, the present application provides a fault detection method for an electric tool, the electric tool comprising a motor, the method comprising: detecting an actual value of a standard parameter of the motor and an actual rotating speed of the motor; determining a first rotating speed change curve of the motor according to the actual value of the standard parameter; obtaining a standard value of the standard parameter, and determining a second rotating speed change curve of the motor according to the standard value; determining a third rotating speed change curve of the motor according to the actual rotating speed; and determining whether the motor has a fault according to the first rotating speed change curve, the second rotating speed change curve and the third rotating speed change curve.

[0021] In some embodiments, the standard parameter comprises at least one of resistance, inductance and stator flux linkage.

[0022] In some embodiments, the method comprises: determining whether a stator of the motor has a fault according to the actual value of the resistance and the standard value of the resistance.

[0023] In some embodiments, the method comprises: determining whether a stator of the motor has a fault according to the actual value of the inductance and the standard value of the inductance.

[0024] In some embodiments, the method comprises: determining whether a rotor of the motor has a fault according to the actual value of the stator flux linkage and the standard value of the stator flux linkage. BRIEF DESCRIPTION OF DRAWINGS

[0025] FIG. 1 is a structural schematic diagram of an electric tool according to an embodiment of the present application;

[0026] Fig. 2 is a structural schematic diagram of a control circuit provided by the present application;

[0027] Fig. 3 is a first speed change curve obtained in a detection mode. [0027.1][According to the rules 91 correction 02.07.2025]Fig. 4 is a schematic diagram of a power tool fault detection process provided by an embodiment of the present application. DETAILED DESCRIPTION

[0028] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above-described accompanying drawings.

[0029] In the present application, the terms "comprising", "including", "containing", "have" or any other similar words are intended to encompass non-exclusive inclusion, so that a process, method, article or apparatus including a series of elements includes not only those elements, but also other elements not explicitly listed, or other elements inherent to such a process, method, article or apparatus. Without more limitations, the element defined by the phrase "including a" does not exclude the presence of additional identical elements in the process, method, article or apparatus including the element.

[0030] In the present application, the term "and / or" is a description of the association relationship between the associated objects, which means that there can be three relationships. For example, A and / or B can represent the following three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents a "and / or" relationship between the preceding and following associated objects.

[0031] In the present application, the terms "connection", "combination", "coupling", "mounting" can be direct connection, combination, coupling or mounting, or indirect connection, combination, coupling or mounting. Among them, for example, direct connection refers to the connection of two parts or components without the need for an intermediate part, and indirect connection refers to the connection of two parts or components with at least one intermediate part. In addition, "connection" and "coupling" are not limited to physical or mechanical connection or coupling, and can include electrical connection or coupling.

[0032] In this application, those of ordinary skill in the art will understand that the relative terms used in connection with a quantity or a condition (for example, "about", "approximately", "substantially" and the like) include the stated value and have the meaning indicated by the context. For example, the relative terms at least include the degree of error related to the measurement of a specific value, the tolerance caused by manufacturing, assembly, use, and the like related to a specific value. Such terms should also be considered to disclose the range defined by the absolute values of the two endpoints. The relative terms can refer to the addition or subtraction of a certain percentage (for example, 1%, 5%, 10% or more) of the indicated value. The numerical value without the relative term should also be disclosed as a specific value with a tolerance. In addition, "substantially" when expressing the relative angular positional relationship (for example, substantially parallel, substantially perpendicular), can refer to the addition or subtraction of a certain degree (for example, 1 degree, 5 degrees, 10 degrees or more) based on the indicated angle.

[0033] In this application, those of ordinary skill in the art will understand that the functions performed by the components can be performed by one component, multiple components, one part, or multiple parts. Similarly, the functions performed by the parts can also be performed by one part, one component, or multiple parts in combination.

[0034] In this application, the terms "upper", "lower", "left", "right", "front", "back" and the like are described in the orientation and positional relationship shown in the drawings, and should not be understood as limiting the embodiments of the present application. In addition, it is also understood in the context that when referring to one element connected to another element "on" or "under", it can not only be directly connected to another element "on" or "under", but also indirectly connected to another element "on" or "under" through an intermediate element. It should also be understood that the terms "upper", "lower", "left", "right", "front", "back" and the like not only represent the positive direction, but also can be understood as the side direction. For example, the lower side can include the directly below, the left below, the right below, the front below and the back below, etc.

[0035] In this application, the terms "controller", "processor", "central processing unit", "CPU", "MCU" can be interchangeable. When a single unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a specific function, unless otherwise specified, these functions can be performed by a single unit or multiple units.

[0036] In this application, the terms "device", "module" or "unit" can be implemented in the form of hardware or software to achieve a specific function.

[0037] In this application, the terms "calculate", "determine", "control", "determine", "identify" and the like refer to the operations and processes of a computer system or similar electronic computing device (for example, controller, processor, etc.).

[0038] For the purpose of clarity, the terms upper side, lower side, left side, right side, front side and rear side are defined in the drawings of the present application.

[0039] The present application will be described in detail below with reference to the drawings and specific embodiments.

[0040] The electric power tool can be a garden tool, such as a grass trimmer, a blower, a walk-behind electric power tool, such as a lawn mower, a chain saw, a washer, etc. Alternatively, the electric power tool can also be a decoration tool, such as a screwdriver / drill / wrench, an electric hammer, a nail gun, a sander, etc. Alternatively, the electric power tool can also be a saw tool, such as a jigsaw, a scroll saw, a circular saw, etc. Alternatively, the electric power tool can also be other bench-type tools, such as a bench saw, a metal cutting machine, a wood milling machine, etc. Alternatively, the electric power tool can also be a polishing tool, such as an angle grinder, a sander, etc. Alternatively, the electric power tool can also be other electric power tools, such as a fan, etc. Alternatively, the walking device that does not travel on the road, such as a multipurpose vehicle, can also be a sand vehicle, a UTV (farmer vehicle), a golf vehicle, an all-terrain vehicle (ATV), and can also be an agricultural machinery vehicle, such as a harvester, a pesticide spraying vehicle, etc. Of course, it can be understood that for the walking device, it can also be a washer. It can also be an intelligent walking electric power tool with a lighting device and implementing a working function, such as an intelligent lawn mower, etc. For example, the electric power tool can also be a power head including a lighting device such as a lamp. The power head is configured to adapt to some output components to realize the function of the tool.

[0041] The present application does not limit the type of electric power tool. As long as the electric power tool can adopt the essential content of the technical solution disclosed below, it falls within the protection scope of the present application.

[0042] FIG. 1 is a structural schematic diagram of an electric power tool provided by an embodiment of the present application. Referring to FIG. 1, the electric power tool provided by the present application takes an impact tool as an example in this embodiment. The impact tool is an impact screwdriver 100. It can be understood that in other alternative embodiments, the impact tool can be installed with different working attachments, so that the impact tool can be, for example, an impact drill, an impact wrench, etc.

[0043] The impact screwdriver 100 includes a power supply. In this embodiment, the power supply is a direct current power supply 30. The direct current power supply 30 is configured to provide electric energy for the impact screwdriver 100. In an alternative embodiment, the direct current power supply 30 is a battery pack, which cooperates with a corresponding power supply circuit to supply power to the impact screwdriver 100. It should be understood by those skilled in the art that the power supply is not limited to the scenario of using a direct current power supply, but can also be achieved by using a mains power supply, an alternating current power supply, cooperating with a corresponding rectification, filtering and voltage regulation circuit, to supply power to the corresponding components in the machine.

[0044] As shown in FIG. 1, the impact screwdriver 100 includes a housing 11, a motor 12, an output mechanism 13, a transmission mechanism 14, an impact mechanism 15, and a control circuit (not shown). In the present embodiment, the motor 12 is specifically configured as an electric motor, and hereinafter the motor 12 will be used in place of the motor, and the motor shaft will be used in place of the drive shaft, but this should not be construed as limiting the present application.

[0045] The housing 11 is formed or connected with a grip 113 for user operation. The grip 113 forms a T-shaped or L-shaped structure with the housing 11, which is convenient for user holding and operation. One end of the grip 113 is connected with a direct current power supply 30. The motor 12, the transmission mechanism 14, the impact mechanism 15, and the output mechanism 13 are arranged in the housing 11.

[0046] The motor 12 includes a stator winding and a rotor. In some embodiments, the motor 12 is a three-phase brushless motor, including a rotor with permanent magnets and a three-phase stator winding U, V, W that is electronically commutated. In some embodiments, the three-phase stator winding U, V, W is connected in a star configuration, and in other embodiments, the three-phase stator winding U, V, W is connected in a delta configuration. However, it will be understood that other types of brushless motors are within the scope of the present disclosure. The brushless motor can include fewer or more than three phase windings.

[0047] Figure 2 is a schematic diagram of a control circuit according to an embodiment of the present application. Referring to Figure 2, the impact screwdriver 100 comprises a control circuit. The control circuit comprises a drive circuit 171 and a controller 17. The drive circuit 171 is electrically connected to the stator windings U, V, W of the motor 12 and is configured to deliver current from the DC power supply 30 to the stator windings U, V, W to drive the motor 12 to rotate. In one embodiment, the drive circuit 171 comprises a plurality of switching elements Q1, Q2, Q3, Q4, Q5, Q6. The gate terminal of each switching element is electrically connected to the controller 17 and is configured to receive a control signal from the controller 17. The drain or source terminal of each switching element is connected to the stator windings U, V, W of the motor 12. The switching elements Q1-Q6 receive the control signal from the controller 17 to change their respective conduction states, thereby changing the current and / or voltage supplied by the DC power supply 30 to the stator windings U, V, W of the motor 12 to drive the motor 12 to operate. In one embodiment, the drive circuit can be a three-phase bridge driver circuit comprising six controllable semiconductor power devices (e.g. Field Effect Transistors (FETs), Bipolar Junction Transistors (BJTs), Insulated Gate Bipolar Transistors (IGBTs), etc.). It will be appreciated that the switching elements described above can also be any other type of solid state switch, such as Insulated Gate Bipolar Transistors (IGBTs), Bipolar Junction Transistors (BJTs), etc.

[0048] The control circuit further comprises a parameter detection module 13 configured to detect at least an actual value of a standard parameter of the motor 12. In an optional embodiment, the standard parameter comprises at least one of the resistance, inductance and stator flux linkage of the motor 12. For example, the standard parameter can comprise the resistance of the motor, or the inductance of the motor, or the stator flux linkage of the motor, or the resistance and inductance of the motor, or the resistance and stator flux linkage of the motor, or the inductance and stator flux linkage of the motor, or the resistance, inductance and stator flux linkage of the motor. In an exemplary embodiment, the method of obtaining the standard parameter of the motor can be obtained directly by a sensor or the like, or can be obtained by calculation of other related parameters, which is not limited in the present embodiment.

[0049] In the present embodiment, the controller 17 is configured to determine a first rotational speed variation curve of the motor according to the actual value of the standard parameter, to obtain a standard value of the standard parameter and determine a second rotational speed variation curve of the motor according to the standard value, and to determine whether the motor has failed according to the first rotational speed variation curve and the second rotational speed variation curve.

[0050] The first rotation speed change curve is a curve of the rotation speed of the motor changing with the detection times according to the actual value of the standard parameter.

[0051] In an optional embodiment, the first rotation speed change curve of the motor is obtained multiple times in an offline manner. The offline manner can be understood as obtaining the actual value of the standard parameter in a detection mode. The detection mode is a mode different from the working mode of the motor. For example, when the motor is maintained after being sold, the maintenance technician can make the motor enter the detection mode through corresponding instructions. In an optional embodiment, FIG. 3 is the first rotation speed change curve obtained in the detection mode. The detection mode can control the motor to start and stop continuously multiple times, so that the rotation speed of the motor can be accelerated from 0 to the set speed multiple times, and thus the first rotation speed change curve as shown in FIG. 3 can be obtained to ensure the accuracy of the result. It should be noted that FIG. 3 is only an exemplary first rotation speed change curve. In fact, in the detection mode, the user can set the number of start and stop of the motor according to the actual demand, so as to obtain the first rotation speed change curve of the ideal start and stop times.

[0052] In other embodiments, the first rotation speed change curve of the motor can also be obtained in an online manner. The online manner can be understood as obtaining the actual value of the standard parameter in the working mode of the motor, so that the user can detect whether the motor is faulty. It can be understood that in the working mode of the motor, there is generally no control of multiple start and stop. It can be understood that the first rotation speed change curve of the motor obtained in the working mode of the motor includes one start and stop of the motor, and the rotation speed of the motor in the one start and stop process is used to determine the first rotation speed change curve.

[0053] The standard value of the standard parameter is pre-stored in the controller of the motor. In an optional embodiment, the standard value of the standard parameter is the factory value of the standard parameter. The second rotation speed change curve is a curve of the change of the rotation speed of the motor according to the standard value of the standard parameter.

[0054] The motor failure includes but is not limited to the stator failure, the rotor failure, the demagnetization of the permanent magnet in the motor or the mechanical structure of the motor being stuck, etc., which causes the motor to have problems in the rotation process or the motor to be unable to rotate. When the motor fails, the actual value of the standard parameter of the motor cannot correspond to the standard value of the standard parameter, or the rotation speed value in the first rotation speed change curve determined according to the actual value of the standard parameter does not correspond to the rotation speed value at the corresponding position in the second rotation speed change curve determined according to the standard value of the standard parameter. Therefore, whether the motor fails can be determined according to the first rotation speed change curve and the second rotation speed change curve by comparing the rotation speed values at the corresponding positions in the first rotation speed change curve and the second rotation speed change curve.

[0055] In the embodiment, the control circuit of the power tool comprises a parameter detection module and a controller, the parameter detection module is configured to detect actual values of standard parameters of the motor, the controller is configured to determine a first speed change curve of the motor according to the actual values of the standard parameters, determine a second speed change curve of the motor according to standard values of the standard parameters, and determine whether the motor is faulty according to the first speed change curve and the second speed change curve, so that the state of the motor can be accurately and quickly identified in the product development stage or the after-sales maintenance stage without disassembling the motor according to the standard parameters of the motor identified offline or online, the operation is simple, and the identification accuracy is high.

[0056] Optionally, the controller is configured to determine that the motor is faulty if a difference between at least one corresponding point in the first speed change curve and the second speed change curve is greater than or equal to a first set value.

[0057] The first set value can be less than or equal to a difference between the acceptable actual speed and the standard speed, and the first set value can be 500 rpm, for example. If the difference between at least one corresponding point in the first speed change curve and the second speed change curve is greater than or equal to the first set value, it can be understood that the difference between one corresponding point in the first speed change curve and the second speed change curve is greater than or equal to the first set value, or the difference between multiple corresponding points in the first speed change curve and the second speed change curve is greater than or equal to the first set value. When the difference between at least one corresponding point in the first speed change curve and the second speed change curve is greater than or equal to the first set value, it indicates that in the first speed change curve, the actual speed value of the motor does not match the standard speed value thereof, and at this time, it can be determined that the motor is faulty.

[0058] Optionally, when the standard parameters comprise resistance, inductance and stator flux linkage, the controller is configured to determine the actual speed and the standard speed of the motor at each time according to Formula One, determine the first speed change curve according to the actual speed of the motor at each time, and determine the second speed change curve according to the standard speed of the motor at each time.

[0059] Formula One is as follows: n = (θ^2-θ^1) / (△t); wherein n is the speed of the motor at the current time, θ^1 is the stator flux linkage angle of the motor at the previous time, θ^2 is the stator flux linkage angle of the motor at the current time, and △t is the time difference between the current time and the previous time.

[0060] In an optional embodiment, the stator flux linkage angle θ^ of the motor can be represented as:

[0061] wherein,

[0062] Wherein, L is the inductance of the motor; is the stator flux of the motor; is the resistance of the motor; is the stator flux angle of the motor; the three-phase current is changed into two items after the Clarke transformation, corresponding to the α axis and the β axis, iα is the α axis current, iβ is the β axis current, iαβ represents the vector sum of the α axis current and the β axis current, vα is the α axis voltage, vβ is the β axis voltage, and vαβ represents the vector sum of the α axis voltage and the β axis voltage.

[0063] Wherein, the actual speed of the motor at each moment is the speed of the motor obtained by bringing the actual values of the resistance, inductance and stator flux of the motor at each moment into formula one. The standard speed of the motor at each moment is the speed of the motor obtained by bringing the standard values of the resistance, inductance and stator flux of the motor at each moment into formula one. In an optional embodiment, the actual speed of the motor at each moment is introduced into a two-dimensional coordinate, i.e. a first speed change curve is obtained; the standard speed of the motor at each moment is introduced into a two-dimensional coordinate, i.e. a second speed change curve is obtained.

[0064] Optionally, the parameter detection module is further configured to detect the actual speed of the motor, and the controller is further configured to: determine a third speed change curve according to the actual speed; and determine whether the control circuit is faulty according to the third speed change curve and the second speed change curve.

[0065] Wherein, the parameter detection module can include a speed sensor, so that the parameter detection module can detect the actual speed of the motor. The third speed change curve is a curve of the actual speed of the motor detected by the parameter detection module changing with the detection times. The control circuit fault includes a drive circuit fault and / or a controller fault, which causes the control circuit to be unable to correctly control the motor to operate.

[0066] In an embodiment, if it is determined according to the first speed change curve and the second speed change curve that the motor is not faulty, for example, the first speed change curve is basically consistent with the second speed change curve, it can be determined that the motor itself has no fault. However, the motor actually does not rotate according to the set program, so the third speed change curve and the second speed change curve can be used to further determine whether the control circuit is faulty, so that the fault detection of the power tool is more accurate.

[0067] In an optional embodiment, if the difference between at least one corresponding point in the third speed change curve and the second speed change curve is greater than or equal to a second set value, it is determined that the control circuit is faulty. Wherein, the fault of the control circuit can be that the controller outputs an abnormal signal or does not output a control signal or that a certain MOS tube in the control circuit is damaged, etc.

[0068] The second set value can be less than or equal to a difference between the actual detection speed and the standard speed, and for example, the second set value can be 500 rpm. It should be noted that the first set value and the second set value can be the same or different, and the present embodiment does not make a specific limitation thereon, and the values can be set according to actual conditions.

[0069] If the difference between at least one corresponding point in the third speed change curve and the second speed change curve is greater than or equal to the second set value, it can be understood that the difference between one corresponding point in the third speed change curve and the second speed change curve is greater than or equal to the second set value, or the difference between multiple corresponding points in the third speed change curve and the second speed change curve is greater than or equal to the second set value. When the difference between at least one corresponding point in the third speed change curve and the second speed change curve is greater than or equal to the second set value, it indicates that in the third speed change curve, the actual speed value of the motor does not match the standard speed value thereof, and at this time, it can be determined that the control circuit has a fault.

[0070] In an optional embodiment, the controller can be further configured to: determine a first speed change curve of the motor according to the actual value of the standard parameter; obtain a standard value of the standard parameter, and determine a second speed change curve of the motor according to the standard value; determine a third speed change curve of the motor according to the actual speed; and determine whether the motor has a fault according to the first speed change curve, the second speed change curve and the third speed change curve.

[0071] The determination of whether the motor has a fault according to the first speed change curve, the second speed change curve and the third speed change curve can be performed by comparing corresponding points in the first speed change curve, the second speed change curve and the third speed change curve. When at least one point in the first speed change curve or the third speed change curve does not match a corresponding point in the second speed change curve, it is determined that the motor has a fault, so that the accuracy of the fault detection of the power tool can be further improved. In the present embodiment, the motor fault can be a stator fault, a rotor fault or a control circuit fault.

[0072] Optionally, the controller is further configured to: determine whether the stator of the motor has a fault according to the actual value of the resistance and the standard value of the resistance.

[0073] The actual value of the resistance is obtained by the parameter detection module, and the standard value of the resistance is pre-stored in the controller. The determination of whether the stator of the motor has a fault according to the actual value of the resistance and the standard value of the resistance can be performed by comparing the actual value of the resistance and the standard value of the resistance. If the absolute value of the difference between the actual value of the resistance and the standard value of the resistance is greater than an acceptable resistance difference, it indicates that the stator of the motor has a fault.

[0074] Optionally, the controller is further configured to determine whether the stator of the motor is faulty according to the actual value of the inductance and the standard value of the inductance.

[0075] The actual value of the inductance is obtained by the parameter detection module, and the standard value of the inductance is pre-stored in the controller. According to the actual value of the inductance and the standard value of the inductance, it can be determined whether the stator of the motor is faulty by comparing the actual value of the inductance with the standard value of the inductance. If the absolute value of the difference between the actual value of the inductance and the standard value of the inductance is greater than an acceptable inductance difference, it indicates that the stator of the motor is faulty.

[0076] Optionally, the controller is further configured to determine whether the rotor of the motor is faulty according to the actual value of the stator flux linkage and the standard value of the stator flux linkage.

[0077] The actual value of the stator flux linkage is obtained by the parameter detection module, and the standard value of the stator flux linkage is pre-stored in the controller. According to the actual value of the stator flux linkage and the standard value of the stator flux linkage, it can be determined whether the rotor of the motor is faulty by comparing the actual value of the stator flux linkage with the standard value of the stator flux linkage. If the absolute value of the difference between the actual value of the stator flux linkage and the standard value of the stator flux linkage is greater than an acceptable stator flux linkage difference, it indicates that the rotor of the motor is faulty.

[0078] In an optional embodiment, it can also be determined whether the motor itself or the control circuit is faulty by recognizing the sound data of the motor rotation.

[0079] The sound data of the motor rotation can be, but is not limited to, the sound directly heard by the human ear or the sound collected by the sound sensor arranged on the motor.

[0080] When the sound data of the motor rotation is the sound collected by the sound sensor arranged on the motor, the controller is further configured to obtain the sound collected by the sound sensor when the motor is running, and determine whether the motor itself or the control circuit is faulty according to the sound collected by the sound sensor and the preset sound data pre-stored in the controller, so as to improve the objectivity of the fault of the motor itself or the control circuit.

[0081] In some embodiments, referring to FIG. 4, the method for detecting motor fault in the electric tool includes the following steps:

[0082] S101, detecting the actual value of the standard parameter of the motor and the actual rotation speed of the motor.

[0083] S102, determining the first rotation speed change curve of the motor according to the actual value of the standard parameter.

[0084] S103, obtaining the standard value of the standard parameter, and determining the second rotation speed change curve of the motor according to the standard value.

[0085] S104, determining a third speed change curve of the motor according to the actual speed.

[0086] S105, determining whether the motor is faulty according to the first speed change curve, the second speed change curve and the third speed change curve.

[0087] The basic principles, main features and advantages of the present application are shown and described above. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the protection scope of the present application.

Claims

1. A power tool, wherein, The application relates to a motor control circuit, comprising: a housing; a motor comprising a stator and a rotor; a control circuit configured to control the operation of the motor; the control circuit comprising a parameter detection module and a controller; the parameter detection module being configured to detect at least an actual value of a standard parameter of the motor; the controller being configured to: determine a first speed change curve of the motor according to the actual value of the standard parameter; obtain a standard value of the standard parameter and determine a second speed change curve of the motor according to the standard value; determine whether the motor is faulty according to the first speed change curve and the second speed change curve.

2. The power tool of claim 1, wherein, The standard parameter comprises at least one of a resistance, an inductance and a stator flux linkage.

3. The power tool of claim 2, wherein, The standard parameter comprises the resistance, the inductance and the stator flux linkage, and the controller is configured to: determine an actual speed and a standard speed of the motor at each moment according to a formula one; determine the first speed change curve according to the actual speed of the motor at each moment and determine the second speed change curve according to the standard speed of the motor at each moment; the formula one is as follows: n = (theta^2 - theta^1) / (delta t); wherein n is the speed of the motor at a current moment, theta^1 is a stator flux linkage angle of the motor at a previous moment, theta^2 is a stator flux linkage angle of the motor at the current moment, and delta t is a time difference value between the current moment and the previous moment.

4. The power tool of claim 1, wherein, The controller is configured to: if a difference value of at least one corresponding point in the first speed change curve and the second speed change curve is greater than or equal to a first set value, it is determined that the motor is faulty.

5. The power tool of claim 1, wherein, The parameter detection module is further configured to detect an actual speed of the motor, and the controller is further configured to determine a third speed change curve according to the actual speed and determine whether the control circuit is faulty according to the third speed change curve and the second speed change curve.

6. The power tool of claim 1, wherein, The controller is configured to obtain the actual value of the standard parameter offline in a detection mode.

7. The power tool of claim 1, wherein, The controller is configured to obtain the actual value of the standard parameter online in a working mode.

8. The power tool of claim 2, wherein, The controller is configured to determine whether the stator of the motor is faulty according to the actual value of the resistance and the standard value of the resistance.

9. The power tool of claim 2, wherein, The controller is configured to determine whether the stator of the motor is faulty according to the actual value of the inductance and the standard value of the inductance.

10. The power tool of claim 2, wherein, The controller is configured to determine whether the rotor of the motor is faulty according to the actual value of the stator flux linkage and the standard value of the stator flux linkage.

11. A power tool, wherein, The application relates to a motor control circuit, comprising: a housing; a motor comprising a stator and a rotor; a control circuit configured to control the operation of the motor; the control circuit comprising a parameter detection module and a controller; the parameter detection module being configured to detect at least an actual value of a standard parameter of the motor; the controller being configured to: determine a first speed change curve of the motor according to the actual value of the standard parameter; obtain a standard value of the standard parameter and determine a second speed change curve of the motor according to the standard value; determine whether the motor is faulty according to the first speed change curve and the second speed change curve. determining a third speed change curve of the motor according to the actual speed; determining whether the motor has a fault according to the first speed change curve, the second speed change curve and the third speed change curve.

12. The power tool of claim 11, wherein, The standard parameter comprises at least one of resistance, inductance and stator flux linkage.

13. The power tool of claim 11, wherein, The controller is configured to determine whether the motor has a stator fault, a rotor fault or a control circuit fault according to the first speed change curve, the second speed change curve and the third speed change curve.

14. The power tool of claim 12, wherein, The controller is configured to determine whether the rotor of the motor has a fault according to the actual value of the stator flux linkage and the standard value of the stator flux linkage.

15. The power tool of claim 11, wherein, The controller is configured to obtain the actual value of the standard parameter offline in a detection mode or online in a working mode.

16. A motor tool fault detection method, the motor tool comprising a motor, the method comprising: detecting an actual value of a standard parameter of the motor and an actual speed of the motor; determining a first speed change curve of the motor according to the actual value of the standard parameter; obtaining a standard value of the standard parameter and determining a second speed change curve of the motor according to the standard value; determining a third speed change curve of the motor according to the actual speed; determining whether the motor has a fault according to the first speed change curve, the second speed change curve and the third speed change curve.

17. The method of claim 16, wherein, The standard parameter comprises at least one of resistance, inductance and stator flux linkage.

18. The method of claim 17, wherein, The method comprises determining whether the stator of the motor has a fault according to the actual value of the resistance and the standard value of the resistance.

19. The method of claim 17, wherein, The method comprises determining whether the stator of the motor has a fault according to the actual value of the inductance and the standard value of the inductance.

20. The method of claim 17, wherein, The method comprises determining whether the rotor of the motor has a fault according to the actual value of the stator flux linkage and the standard value of the stator flux linkage.

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