Electric tool

Abstract

The invention discloses an electric tool. The electric tool comprises a shell; the motor comprises a stator and a rotor; the control circuit is used for controlling the operation of the motor; the control circuit comprises a parameter detection module and a controller; the parameter detection module is at least used for detecting actual values of standard parameters 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; obtaining a standard value of the standard parameter, and determining a second rotating speed change curve of the motor according to the standard value; and determining whether the motor breaks down according to the first rotating speed change curve and the second rotating speed change curve. According to the technical scheme, the state of the motor can be accurately and rapidly identified without disassembling diagnosis of the motor, the operation is simple, and the identification precision is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of tool equipment, and particularly relates to an electric tool. BACKGROUND

[0002] In the related art, an electric tool monitors and controls possible faults in the working process of a motor, such as overcurrent protection or locked-rotor protection. However, after the electric 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 rotating process. If such faults are not found in time, the motor will be further damaged in severe cases.

[0003] This section provides background information relating to the present application, which is not necessarily prior art. SUMMARY

[0004] It is an object of the present application to solve or at least alleviate part or all of the above problems. To this end, it is an object of the present application to provide an electric tool capable of detecting whether a motor is faulty.

[0005] To achieve the above object, the present application adopts the following technical solutions:

[0006] In some embodiments, the present application provides an electric tool, comprising:

[0007] a housing;

[0008] a motor comprising a stator and a rotor;

[0009] a control circuit for controlling the operation of the motor;

[0010] the control circuit comprises a parameter detection module and a controller;

[0011] the parameter detection module is configured to detect at least an actual value of a standard parameter of the motor;

[0012] the controller is configured to:

[0013] determine a first rotational speed change curve of the motor according to the actual value of the standard parameter;

[0014] obtain a standard value of the standard parameter and determine a second rotational speed change curve of the motor according to the standard value;

[0015] determine whether the motor is faulty according to the first rotational speed change curve and the second rotational speed change curve.

[0016] In some embodiments, the standard parameter comprises at least one of a resistance, an inductance and a stator flux linkage.

[0017] In some embodiments, the standard parameters include resistance, inductance and stator flux linkage, and the controller is specifically configured to:

[0018] determine the actual speed of the motor at each time according to formula one, and determine the standard speed of the motor at each time according to formula two;

[0019] 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;

[0020] Formula one is as follows:

[0021] wherein n is the speed of the motor at the current time, is the stator flux linkage angle of the motor at the previous time, 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.

[0022] In some embodiments, the controller is specifically configured to:

[0023] 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, it is determined that the motor has a fault.

[0024] 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.

[0025] In some embodiments, the controller is specifically configured to: offline acquire the actual value of the standard parameter in the detection mode.

[0026] In some embodiments, the controller is specifically configured to: online acquire the actual value of the standard parameter in the working mode.

[0027] 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.

[0028] 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.

[0029] 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.

[0030] In a second aspect, the present application further provides an electric tool, comprising:

[0031] A housing;

[0032] A motor, the motor is arranged in the housing;

[0033] A control circuit, configured to control the operation of the motor;

[0034] The control circuit comprises a parameter detection module and a controller;

[0035] 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;

[0036] The controller is configured to:

[0037] determine a first rotating speed change curve of the motor according to the actual value of the standard parameter;

[0038] obtain a standard value of the standard parameter, and determine a second rotating speed change curve of the motor according to the standard value;

[0039] determine a third rotating speed change curve of the motor according to the actual rotating speed;

[0040] 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.

[0041] In some embodiments, the standard parameter comprises at least one of a resistance, an inductance and a stator flux linkage.

[0042] In some embodiments, the controller is specifically 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.

[0043] The present application has the advantages that: by making the control circuit of the power tool comprise a parameter detection module and a controller, and making the parameter detection module at least detect an actual value of a standard parameter of the motor, and making the controller of the control circuit be configured to determine a first rotating speed change curve of the motor according to the actual value of the standard parameter, and obtain a standard value of the standard parameter, and determine a second rotating speed change curve of the motor according to the standard value, so as to determine whether the motor has a fault according to the first rotating speed change curve and the second rotating speed change curve, the state of the motor can be accurately and quickly identified without disassembling the motor during the product development stage or the after-sales maintenance stage according to the standard parameter of the motor identified offline or online, the operation is simple, and the identification accuracy is high. BRIEF DESCRIPTION OF DRAWINGS

[0044] Figure 1 A structural schematic diagram of a power tool provided by an embodiment of the present application;

[0045] Figure 2A structural schematic diagram of a control circuit provided in the present application is shown in FIG. 1.

[0046] Figure 3 A first speed change curve obtained in the detection mode. DETAILED DESCRIPTION

[0047] 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.

[0048] In the present application, the terms "comprise", "contain", "have" or any other variant thereof are intended to cover non-exclusive inclusions, so that the process, method, article or device including a series of elements not only includes those elements, but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without more limitations, the element defined by the statement "comprising a" does not exclude the presence of other identical elements in the process, method, article or device comprising the element.

[0049] 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 kinds of relationships. For example, A and / or B can represent three cases: A exists alone, A and B exist together, and B exists alone. In addition, the character " / " in the present application generally represents that the front and rear associated objects are in a "and / or" relationship.

[0050] 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. The two parts or components are connected through the intermediate part. In addition, "connection" and "coupling" are not limited to physical or mechanical connection or coupling, and can include electrical connection or coupling.

[0051] 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 associated with the measurement of a particular value, the tolerance caused by manufacturing, assembly, use, and the like associated with a particular value. Such terms should also be considered to disclose a range defined by the absolute values of the two endpoints. The relative terms can refer to a certain percentage (for example, 1%, 5%, 10% or more) of the indicated value plus or minus. 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 a certain number of degrees (for example, 1 degree, 5 degrees, 10 degrees or more) plus or minus the indicated angle.

[0052] 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.

[0053] 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 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, left below, right below, front below and back below, etc.

[0054] In this application, the terms "controller", "processor", "central processing unit", "CPU", "MCU" can be interchangeable. When a 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.

[0055] In this application, the terms "device", "module" or "unit" can be realized in the form of hardware or software to achieve a specific function.

[0056] 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.).

[0057] To clearly illustrate the technical solution of this application, the terms "upper side", "lower side", "left side", "right side", "front side" and "rear side" are defined in the accompanying drawings.

[0058] The present application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0059] Power tools can be garden tools, such as lawnmowers, hair dryers, and walk-behind power tools such as lawnmowers, chainsaws, and washing machines. Alternatively, power tools can be finishing tools, such as screwdrivers / drills / wrenches, hammer drills, nail guns, and sanders. Power tools can also be sawing tools, such as reciprocating saws, jigsaws, and circular saws. Power tools can also be other table-type tools, such as table saws, metal cutters, and electric milling machines. Power tools can also be sanding tools, such as angle grinders and sanders. Power tools can also be other types of power tools, such as fans. They can also be non-road-mobile vehicles, such as multi-purpose vehicles, ATVs, UTVs (farm vehicles), golf carts, and ATVs, as well as agricultural machinery vehicles, such as harvesters and sprayers. Of course, it's understandable that walk-behind vehicles can also include washing machines. They can also be intelligent walk-behind power tools with lighting and operational functions, such as intelligent lawnmowers. For example, a power tool can also be a power head, which includes a lighting device such as a lamp. The power head is used to adapt some output components to enable the tool's function.

[0060] This application does not limit the type of power tool. Any power tool that adopts the substantive content of the technical solution disclosed below will fall within the protection scope of this application.

[0061] Figure 1 This is a schematic diagram of the structure of a power tool provided in an embodiment of this application, with reference to... Figure 1 As shown, the power tool provided in this application is exemplified by an impact tool in this embodiment. This impact tool is an impact screwdriver 100. It is understood that in other alternative embodiments, the impact tool can be equipped with different working attachments, allowing the impact tool to be, for example, an impact drill, an impact wrench, etc.

[0062] The impact screwdriver 100 includes a power supply. In this embodiment, the power supply is a DC power supply 30. The DC power supply 30 is used to provide electrical energy to the impact screwdriver 100. In an optional embodiment, the DC power supply 30 is a battery pack, which, in conjunction with a corresponding power circuit, supplies power to the impact screwdriver 100. Those skilled in the art should understand that the power supply is not limited to scenarios using DC power; it can also be powered by mains power or AC power, in conjunction with corresponding rectification, filtering, and voltage regulation circuits, to power corresponding components within the machine.

[0063] As shown in Figure 1 , the impact screwdriver 100 comprises 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 figure). In the present embodiment, the motor 12 is specifically configured as an electric motor, and hereinafter the motor 12 will be used instead of the motor, and the motor shaft will be used instead of the drive shaft, but this cannot be regarded as a limitation to the present application.

[0064] The housing 11 is formed or connected with a holding portion 113 for user operation. The holding portion 113 forms a T-shaped or L-shaped structure with the housing 11, which is convenient for user to hold and operate. One end of the holding portion 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.

[0065] The motor 12 comprises a stator winding and a rotor. In some embodiments, the motor 12 is a three-phase brushless motor, comprising a rotor with permanent magnets and a three-phase stator winding U, V, W which is electronically commutated. In some embodiments, the three-phase stator winding U, V, W is connected in star, and in other embodiments, the three-phase stator winding U, V, W is connected in delta. However, it can be understood that other types of brushless motors are also within the scope of the present disclosure. The brushless motor can comprise less than or more than three-phase winding.

[0066] Figure 2 A structural schematic diagram of a control circuit provided in the present application is shown in Figure 2As shown, the impact screwdriver 100 comprises a control circuit. The control circuit comprises a driving circuit 171 and a controller 17. The driving circuit 171 is electrically connected with the stator windings U, V, W of the motor 12, for transmitting the 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 driving circuit 171 comprises a plurality of switching elements Q1, Q2, Q3, Q4, Q5, Q6. The gate terminal of each switching element is electrically connected with the controller 17, for receiving the control signal from the controller 17. The drain or source terminal of each switching element is connected with 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 the respective conduction state, thereby changing the current and / or voltage of the DC power supply 30 loaded on the stator windings U, V, W of the motor 12, to drive the motor 12 to operate. In one embodiment, the driving circuit can be a three-phase bridge driver circuit comprising six controllable semiconductor power devices (for example, Field Effect Transistor (FET), Bipolar Junction Transistor (BJT), Insulated Gate Bipolar Transistor (IGBT), etc.). It can be understood that the above-mentioned switching elements can also be any other type of solid-state switch, such as Insulated Gate Bipolar Transistor (IGBT), Bipolar Junction Transistor (BJT), etc.

[0067] The control circuit further comprises a parameter detection module 13, which is 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 for obtaining the standard parameter of the motor can be directly obtained by a sensor or the like device, or can be obtained by calculation of other related parameters, which is not limited in the present embodiment.

[0068] In the present embodiment, the controller 17 is 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; and determine whether the motor fails according to the first speed change curve and the second speed change curve.

[0069] In the present embodiment, the first speed change curve is a curve of the speed of the motor changing with the detection times according to the actual value of the standard parameter.

[0070] In an optional embodiment, the first 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, Figure 3 For the first speed change curve obtained in the detection mode, the motor can be controlled to start and stop continuously multiple times, so that the speed of the motor can be accelerated from 0 to the set speed multiple times, so that the first speed change curve as shown in Figure 3 can be obtained to ensure the accuracy of the result. It should be noted that Figure 3 The first speed change curve is only an example. In fact, in the detection mode, the user can set the number of start and stop of the motor according to the actual needs, so as to obtain the first speed change curve of the ideal start and stop times.

[0071] In other embodiments, the first 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, and it can be understood that the first speed change curve of the motor obtained in the working mode of the motor includes a start and stop of the motor, and the speed of the motor in the start and stop process determines the first speed change curve.

[0072] 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 speed change curve is a curve of the change of the speed of the motor determined according to the standard value of the standard parameter.

[0073] The motor failure includes but is not limited to stator failure, rotor failure, demagnetization of permanent magnet in the motor or mechanical structure of the motor stuck, etc., which causes problems in the rotation process of the motor or the motor cannot 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 speed value in the first speed change curve determined according to the actual value of the standard parameter does not correspond to the speed value at the corresponding position in the second 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 speed change curve and the second speed change curve by comparing the speed values at the corresponding positions in the first speed change curve and the second speed change curve.

[0074] 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 at least an actual value of a standard parameter of the motor, the controller is configured to determine a first speed change curve of the motor according to the actual value of the standard parameter, determine a standard value of the standard parameter, and determine a second speed change curve of the motor according to the standard value, 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, the operation is simple, and the identification accuracy is high.

[0075] Optionally, the controller is specifically configured to: if a 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, it is determined that the motor is faulty.

[0076] 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 of 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 of 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 of 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 of 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.

[0077] Optionally, when the standard parameter comprises resistance, inductance and stator flux linkage, the controller is specifically 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.

[0078] Formula One is as follows: Wherein, n is the speed of the motor at the current time, is the stator flux linkage angle of the motor at the previous time, 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.

[0079] In an optional embodiment, the stator flux linkage angle of the motor may be expressed as:

[0080]

[0081] wherein,

[0082] η(x) = x - Li αβ .

[0083]

[0084]

[0085] y = -R s i αβ +v αβ .。

[0086] wherein, L is the inductance of the motor; ψ m is the stator flux of the motor; R s is the resistance of the motor; θ is the stator flux angle of the motor; the three-phase current is converted into two items after the Clarke transformation, corresponding to the α axis and the β axis, i α is the α axis current, i β is the β axis current, i αβ represents the vector sum of the α axis current and the β axis current, v α is the α axis voltage, v β is the β axis voltage, v αβ represents the vector sum of the α axis voltage and the β axis voltage.

[0087] 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.

[0088] 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.

[0089] 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 number of detections. 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.

[0090] In one embodiment, if it is determined that the motor does not have a fault according to the first speed change curve and the second speed change curve, for example, the first speed change curve is substantially consistent with the second speed change curve, it can be determined that the motor itself does not have a fault. However, the motor does not actually rotate according to the set program, and it can be further determined whether the control circuit has a fault through the third speed change curve and the second speed change curve, so that the fault detection of the electric tool is more accurate.

[0091] In an optional embodiment, if the difference of 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 is determined that the control circuit has a fault. Wherein, the fault of the control circuit can be that the controller output signal is abnormal or does not output the control signal or a MOS tube in the control circuit is damaged, etc.

[0092] Wherein, the second set value can be less than or equal to the difference between the actual detection speed and the standard speed, 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 value or different values, and the present embodiment does not make specific limitation, which can be set according to the actual situation.

[0093] If the difference of 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 of 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 of 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 of 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, at this time, it can be determined that the control circuit has a fault.

[0094] In an optional embodiment, the controller can also be configured to: determine the first speed change curve of the motor according to the actual value of the standard parameter; obtain the standard value of the standard parameter, and determine the second speed change curve of the motor according to the standard value; determine the 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.

[0095] According to the first speed change curve, the second speed change curve and the third speed change curve, whether the motor is faulty can be determined by comparing the 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 the corresponding point in the second speed change curve, it is determined that the motor is faulty, thereby further improving the accuracy of the fault detection of the electric tool. In the embodiment, the motor fault can be specifically a stator fault, a rotor fault or a control circuit fault.

[0096] Optionally, the controller is further 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.

[0097] 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. According to the actual value of the resistance and the standard value of the resistance, whether the stator of the motor is faulty can be specifically determined 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 is faulty.

[0098] 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.

[0099] 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, whether the stator of the motor is faulty can be specifically determined by comparing the actual value of the inductance and 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.

[0100] 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.

[0101] 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, whether the rotor of the motor is faulty can be specifically determined by comparing the actual value of the stator flux linkage and 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.

[0102] In an optional embodiment, whether the motor itself or the control circuit is faulty can also be determined by recognizing the sound data of the motor rotating.

[0103] The motor rotation sound data can be, but is not limited to, a sound directly heard by human ears or a sound collected by a sound sensor arranged on the motor.

[0104] When the motor rotation sound data is the sound collected by the sound sensor arranged on the motor, the controller is further configured to: acquire the sound collected by the sound sensor when the motor is running; and determine whether the motor itself or the control circuit fails according to the sound collected by the sound sensor and the preset sound data stored in the controller, so as to improve the objectivity of the motor itself or the control circuit failure.

[0105] 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, characterized in that, include: case; An electric motor, the electric motor comprising a stator and a rotor; A control circuit for controlling the operation of the motor; The control circuit includes: a parameter detection module and a controller; The parameter detection module is used to detect at least the actual values ​​of the standard parameters of the motor. The controller is configured as follows: Based on the actual values ​​of the standard parameters, determine the first speed change curve of the motor; Obtain the standard values ​​of the standard parameters, and determine the second speed change curve of the motor based on the standard values; Based on the first speed change curve and the second speed change curve, determine whether the motor has malfunctioned.

2. The power tool according to claim 1, characterized in that, The standard parameters include at least one of resistance, inductance, and stator flux linkage.

3. The power tool according to claim 2, characterized in that, The standard parameters include the resistor, the inductor, and the stator flux linkage; the controller is specifically configured as follows: According to Formula 1, determine the actual speed and standard speed of the motor at each moment; The first speed change curve is determined based on the actual speed of the motor at each moment, and the second speed change curve is determined based on the standard speed of the motor at each moment. Formula 1 is as follows: Where n is the current rotational speed of the motor. The stator flux linkage angle of the motor mentioned in the previous moment. Δt is the stator flux linkage angle of the motor at the current moment, and Δt is the time difference between the current moment and the previous moment.

4. The power tool according to claim 1, characterized in that, The controller is specifically configured as follows: 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 a first set value, then the motor is determined to have malfunctioned.

5. The power tool according to claim 1, characterized in that, The controller is specifically configured to acquire the actual values ​​of the standard parameters offline in detection mode.

6. The power tool according to claim 1, characterized in that, The controller is specifically configured to acquire the actual values ​​of the standard parameters online in the working mode.

7. The power tool according to claim 2, characterized in that, The controller is configured to determine whether the stator of the motor has failed based on the actual value of the resistor and the standard value of the resistor.

8. The power tool according to claim 2, characterized in that, The controller is configured to determine whether the stator of the motor has failed based on the actual value of the inductance and the standard value of the inductance.

9. The power tool according to claim 2, characterized in that, The controller is configured to determine whether the rotor of the motor has malfunctioned based on the actual value of the stator flux linkage and the standard value of the stator flux linkage.

10. A power tool, characterized in that, include: case; An electric motor, wherein the electric motor is disposed within the housing; A control circuit for controlling the operation of the motor; The control circuit includes: a parameter detection module and a controller; The parameter detection module is used to detect the actual values ​​of the standard parameters of the motor and the actual speed of the motor; The controller is configured as follows: Based on the actual values ​​of the standard parameters, determine the first speed change curve of the motor; Obtain the standard values ​​of the standard parameters, and determine the second speed change curve of the motor based on the standard values; Based on the actual rotational speed, determine the third rotational speed variation curve of the motor; Based on the first speed change curve, the second speed change curve, and the third speed change curve, determine whether the motor has malfunctioned.

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