Electric tool and control method thereof

Abstract

The invention discloses an electric tool and a control method thereof. The electric tool includes: a functional member; the motor is used for driving the functional part to work; the power supply device is at least used for supplying power to the motor; the parameter detection device is connected with the motor and is used for acquiring a plurality of operation parameters of the motor and / or the power supply device; the controller is connected with the driving device and the parameter detection device and is used for controlling the operation of the motor; the controller is configured to detect whether each operating parameter satisfies a strategy switching condition corresponding to the operating parameter; under the condition that any operation parameter meets the corresponding strategy switching condition, a first motor control strategy is adopted to control the motor; and under the condition that each operation parameter does not meet the corresponding strategy switching condition, a second motor control strategy is adopted to control the motor.

Description

Technical Field

[0001] The present application relates to the technical field of electric tools, and in particular to an electric tool and a control method thereof. Background Art

[0002] The functional parts in the electric tool are driven by the motor to perform cutting, tightening, grinding and other operations. The operation of the motor is controlled by the controller. The controller can use different strategies to control the motor to achieve the goals of speed increase or decrease by changing the speed corresponding to the strategy. Among them, when the motor load condition is different, the change trend of the motor speed and the controller's requirements for the motor speed are different. The controller can use different control strategies to control the motor operation according to the current motor load condition.

[0003] This section provides background information related to the present application which is not necessarily prior art. Summary of the invention

[0004] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide an electric tool and a control method thereof.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] An electric tool comprises: a functional part; a motor for driving the functional part to operate; a power supply device, at least for supplying power to the motor; a parameter detection device, connected to the motor and / or the power supply device, for obtaining operating parameters of the motor and / or the power supply device; a controller, connected to the drive device and the parameter detection device, for controlling the operation of the motor; wherein the electric tool further comprises: a temperature detection device, connected to the controller, and configured to obtain the ambient temperature at a temperature measurement point; the controller is configured to: determine a parameter threshold value corresponding to the ambient temperature based on the ambient temperature; determine a current motor control strategy based on a numerical relationship between the operating parameter and the parameter threshold value, and use the motor control strategy to control the motor.

[0007] In some embodiments, the operating parameters include one or more of the motor speed, bus current, bus voltage, phase voltage, PWM duty cycle, demagnetization time, and freewheeling time of the motor.

[0008] In some embodiments, the ambient temperature is any one of the motor temperature, the housing temperature, and the MOS temperature of the power tool.

[0009] In some embodiments, the controller is configured to: when an operating parameter exceeds a parameter threshold, or the calculated value of one or more operating parameters exceeds the parameter threshold, control the motor using a first motor control strategy; when the operating parameter does not exceed the parameter threshold, or the calculated value of one or more operating parameters does not exceed the parameter threshold, control the motor using a second motor control strategy.

[0010] In some embodiments, the controller is configured to: if the motor speed of the motor is less than or equal to a first parameter threshold corresponding to the first ambient temperature, then use a first motor control strategy to control the motor; if the motor speed is greater than the first parameter threshold, then use a second motor control strategy to control the motor.

[0011] In some embodiments, the second parameter threshold corresponding to the second ambient temperature is greater than the first parameter threshold corresponding to the first ambient temperature, and the second ambient temperature is greater than the first ambient temperature.

[0012] In some embodiments, the controller is configured to: adopt a first motor control strategy to control the motor speed of the motor to increase and maintain it at a target high speed under load; adopt a second motor control strategy to control the motor speed of the motor to maintain it at a target low speed under a ready-to-load state, or set the PWM duty cycle of the motor to a target low duty cycle under a ready-to-load state.

[0013] In some embodiments, the controller is further configured to: before the motor enters the loading state, use the third motor control strategy to control the PWM duty cycle of the motor to increase in the no-load state, until the PWM duty cycle reaches the target low duty cycle, then set the PWM duty cycle unchanged, and the motor enters the loading state; determine the no-load speed of the motor when the PWM duty cycle remains unchanged, and determine the corresponding parameter threshold based on the no-load speed and ambient temperature; if the motor speed of the motor is less than or equal to the parameter threshold, use the first motor control strategy to control the motor.

[0014] In some embodiments, the power tool also includes: an operating member for the user to operate to select the current working mode of the power tool, the working mode including at least multiple speed regulation modes and an automatic sensing mode; the controller is also configured to: when the current working mode is the automatic sensing mode, dynamically adjust the motor control strategy based on operating parameters and ambient temperature.

[0015] A control method for an electric tool comprises: a controller of the electric tool receives operating parameters of a motor transmitted by a parameter detection device, and receives an ambient temperature at a temperature measurement point transmitted by a temperature detection device; the controller determines a parameter threshold value corresponding to the ambient temperature according to the ambient temperature; the controller determines a current motor control strategy based on a numerical relationship between the operating parameters and the parameter threshold value, and uses the motor control strategy to control the motor.

[0016] An electric tool comprises: a functional part; a motor for driving the functional part to operate; a power supply device, at least for supplying power to the motor; a parameter detection device, connected to the motor, for obtaining multiple operating parameters of the motor and / or the power supply device; a controller, connected to the drive device and the parameter detection device, for controlling the operation of the motor; wherein the controller is configured to: detect whether each operating parameter satisfies a strategy switching condition corresponding to the operating parameter; if any operating parameter satisfies the corresponding strategy switching condition, use a first motor control strategy to control the motor; if none of the operating parameters satisfies the corresponding strategy switching condition, use a second motor control strategy to control the motor.

[0017] In some embodiments, the operating parameters include at least two of the motor speed, bus current, bus voltage, phase voltage, PWM duty cycle, demagnetization time, and freewheeling time of the motor.

[0018] In some embodiments, the electric tool also includes: a temperature detection device, connected to the controller, configured to obtain the ambient temperature at the temperature measurement point and transmit the ambient temperature to the controller; the controller is configured to: determine the strategy switching conditions corresponding to each operating parameter at the ambient temperature based on the ambient temperature; detect whether each operating parameter meets the strategy switching conditions corresponding to the operating parameter at the ambient temperature, and the strategy switching conditions corresponding to the same operating parameter at different ambient temperatures are different.

[0019] In some embodiments, the ambient temperature is any one of the motor temperature, the housing temperature, and the MOS temperature of the power tool.

[0020] In some embodiments, the controller is configured to periodically detect whether each operating parameter satisfies a corresponding policy switching condition based on a detection period corresponding to each operating parameter.

[0021] In some embodiments, the controller is configured to: adopt a first motor control strategy to control the motor speed of the motor to increase and maintain it at a target high speed under load; adopt a second motor control strategy to control the motor speed of the motor to maintain it at a target low speed under a ready-to-load state, or set the PWM duty cycle of the motor to a target low duty cycle under a ready-to-load state.

[0022] In some embodiments, the controller is configured to: use the operating parameter or the calculated value of the operating parameter exceeding the parameter threshold corresponding to the operating parameter as a strategy switching condition; or use the operating parameter or the calculated value of the operating parameter exceeding the parameter threshold corresponding to the operating parameter at ambient temperature as a strategy switching condition.

[0023] In some embodiments, the controller is further configured to: before the motor enters the waiting-to-load state, use the third motor control strategy to control the motor speed to increase in the no-load state, and then set the motor speed unchanged after the motor speed reaches the target low speed, and the motor enters the waiting-to-load state; if the integral value of the function slope of the bus current of the motor with respect to time within a preset period is greater than or equal to the corresponding current integral threshold, use the first motor control strategy to control the motor.

[0024] In some embodiments, the controller is further configured to: before the motor enters the waiting-to-load state, use the third motor control strategy to control the motor speed of the motor to increase in the no-load state, and then set the motor speed unchanged after the motor speed reaches the target low speed, and the motor enters the waiting-to-load state; if the integral value of the slope of the function of the motor's PWM duty cycle with respect to time within a preset period is greater than or equal to the corresponding duty cycle integral threshold, use the first motor control strategy to control the motor.

[0025] In some embodiments, the controller is further configured to: before the motor enters the waiting-to-load state, use the third motor control strategy to control the PWM duty cycle of the motor to increase in the no-load state, until the PWM duty cycle reaches the target low duty cycle, then set the PWM duty cycle unchanged, and the motor enters the waiting-to-load state; if the integral value of the slope of the function of the motor speed with respect to time within a preset period is less than or equal to the corresponding speed integral threshold, use the first motor control strategy to control the motor.

[0026] A control method for an electric tool comprises: a controller of the electric tool receives a plurality of operating parameters of a motor transmitted by a parameter detection device; the controller detects whether each operating parameter satisfies a strategy switching condition corresponding to the operating parameter; when any operating parameter satisfies the corresponding strategy switching condition, a first motor control strategy is adopted to control the motor; when none of the operating parameters satisfies the corresponding strategy switching condition, a second motor control strategy is adopted to control the motor.

[0027] The benefit of the present application is that when the controller in the power tool switches the motor control strategy according to the motor load condition, it first determines the corresponding parameter threshold value according to the current ambient temperature, and compares the current operating parameters of the motor and / or power supply device with the parameter threshold value corresponding to the current ambient temperature, and then determines which strategy is currently used to control the motor based on the numerical relationship between the two. The parameter thresholds used in this scheme to determine the motor load condition and decide the motor control strategy change with the ambient temperature, avoiding the control failure and malfunction caused by the inability to cope with the influence of temperature changes on the motor operation when using fixed thresholds, and effectively ensuring the accuracy and efficiency of the power tool operation. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1is a plan view of a power tool 100 as an embodiment of the present application;

[0029] Figure 2 is a plan view of a jigsaw 100a as an embodiment of the present application;

[0030] Figure 3 yes Figure 1 The electrical control schematic diagram of the electric tool 100 shown;

[0031] Figure 4 yes Figure 3 A flow chart of a control scheme of a controller in the electric tool 100 controlling the operation of a motor;

[0032] Figure 5 yes Figure 3 A flow chart of another control scheme of the controller in the electric tool 100 controlling the operation of the motor;

[0033] Figure 6 yes Figure 2 A plan view of the lighting assembly 200 in the jig saw 100a is shown;

[0034] Figure 7 yes Figure 2 A perspective view of the lighting operating member 220 in the jig saw 100a shown;

[0035] Figure 8 yes Figure 2 A perspective view of the guard 90 of the jig saw 100a is shown. DETAILED DESCRIPTION

[0036] 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 drawings.

[0037] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0038] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0039] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0040] In the present application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, and the like. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0041] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0042] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0043] In this application, the terms "controller", "processor", "central processing unit", "CPU", and "MCU" are 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.

[0044] In the present application, the terms “device”, “module” or “unit” may be implemented in the form of hardware or software to achieve specific functions.

[0045] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0046] The technical solution proposed in this application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0047] Figure 1 An electric tool 100 is shown as one embodiment in the present application. Figure 1 The electric tool 100 shown is a jigsaw 100a. The electric tool 100 in other embodiments may also be other types of handheld electric tools such as circular saws, reciprocating saws, electric drills, impact wrenches, or bench tools such as miter saws and table saws, or outdoor power equipment such as lawn mowers and snow blowers. The following mainly provides an exemplary description of the jigsaw 100a. However, it is understandable that the electric tool 100 to which the technical solution of the present application is applied is not limited to the jigsaw 100a, nor is it limited to the tool categories described above.

[0048] refer to Figures 1 to 3The electric tool 100 includes a housing 10, an operating member 20, a functional member 30, a motor 40 and a power supply device 50. The housing 10 constitutes the main body of the electric tool 100, which connects or supports the above-mentioned components and forms a storage space, which can accommodate or partially accommodate the above-mentioned components. The operating member 20 is operated by the user to start or stop the motor 40 to be described later, or to adjust the speed of the motor 40 or achieve other functions. In some embodiments, the operating member 20 is electrically connected to the controller 60 to be described later, and can be operated by the user to switch between multiple working modes of the electric tool 100 and transmit the corresponding mode signal to the controller 60, so that the controller 60 determines the current working mode of the electric tool 100 after receiving the mode signal, and then realizes the start and stop, speed regulation or other functions of the motor 40. The functional part 30 is a component in the electric tool 100 that actually performs operations such as cutting, tightening, grinding, and impacting. In this embodiment, the functional part 30 in the jigsaw 100a is a saw blade 31. The jigsaw 100a also includes a clamping device 32 and a transmission assembly 33. The transmission assembly 33 includes an eccentric structure and a reciprocating rod. The saw blade 31 is connected to the clamping device 32, and the clamping device 32 is connected to the reciprocating rod.

[0049] The motor 40 is the prime mover in the electric tool 100. When the motor shaft of the motor 40 rotates, it can drive the functional part 30 directly or indirectly through the transmission assembly. In this embodiment, the motor 40 will drive the reciprocating rod to reciprocate through the eccentric structure in the transmission assembly 33 of the jigsaw 100a, thereby transmitting the power for cutting to the saw blade 31, which is the functional part. In some embodiments, the motor 40 can be a brushless motor. The power supply device 50 can at least supply power to the motor 40, and the power supply of the controller 60, the parameter detection device 70, the temperature detection device 80 and other components to be described later can also be undertaken by the power supply device 50. In some examples, the power supply device 50 can be a battery pack 51, which is detachably connected to the electric tool 100 such as the jigsaw 100a. In other examples, the power supply of the electric tool 100 such as the jigsaw 100a can also be realized by using the mains, AC power supply and cooperating with the power adapter or related circuits such as voltage conversion, rectification, and voltage stabilization.

[0050] refer to Figure 3The electric tool 100 includes a housing 10, an operating part 20, a functional part 30, a motor 40 and a power supply device 50, and also includes a controller 60, a parameter detection device 70 and a temperature detection device 80. The controller 60 includes at least a memory 61 and a processor 62. The memory 61 can be a ROM (Read-Only Memory), a RAM (Random Access Memory), a FLASH (FLASH EEPROM) and a combination thereof, etc., storing a control program executable by the processor 62. The processor 62 can be an MCU (Microcontroller Unit), an ARM (Advanced Reduced Instruction Set Computing Machine), a DSP (Digital Signal Processor), etc., which can read and execute the executable program in the memory 61 to control the operation of the motor 40. The controller 60 has multiple control methods for the motor 40, including but not limited to a six-step commutation control method, a FOC control method, etc. The controller 60 can output corresponding control signals to the motor 40 based on different control methods to make the motor 40 run at the intended speed and direction. Usually, in order to drive the motor 40 to operate normally, the power tool 100 also includes driving devices such as a three-phase inverter bridge and an integrated driving chip.

[0051] The parameter detection device 70 is electrically connected to the motor 40 and electrically or communicatively connected to the controller 60. It can detect one or more of the operating parameters of the motor 40, such as the motor speed, PWM duty cycle, bus voltage, bus current, phase voltage, phase current, freewheeling time, demagnetization time, etc., and transmit the detected operating parameters to the controller 60 for reference. In some embodiments, the parameter detection device 70 can also be electrically connected to a power supply device 50 such as a battery pack 51, and can detect the operating parameters of the battery pack 51, such as the supply voltage, supply current, and battery pack temperature, and can transmit the detected operating parameters of the battery pack to the controller 60 for reference. It is understandable that, depending on the actual scene requirements, the parameter detection device 70 can also detect and transmit to the controller 60 the operating parameters of other types of motors or battery packs not shown above. In some examples, the parameter detection device 70 can be various types of sensors 71.

[0052] The temperature detection device 80 is electrically connected or communicatively connected to the controller 60, and can transmit the detected ambient temperature at each temperature measuring point to the controller 60. The location and number of the temperature measuring points are not specifically limited. The ambient temperature includes but is not limited to the motor temperature of the motor 40 in the power tool 100, the shell temperature of the housing 10, and the MOS temperature. In some examples, the temperature detection device 80 can be a temperature sensor 81.

[0053] In order to ensure the sensitivity, accuracy, temperature adaptability, etc. of the controller 60 in the electric tool 100 when implementing motor control, the controller 60 can consider whether to switch the motor control strategy and what motor control strategy to switch to after receiving the operating parameters of the motor 40 transmitted from the parameter detection device 70 and / or the ambient temperature at the temperature measurement point transmitted from the temperature detection device 80. The motor control strategy is adapted to the current state of the motor 40 in the electric tool 100, and can be used by the controller 60 to decide the motor speed of the motor 40 and the change trend of the motor speed within the current and subsequent certain time period.

[0054] The state of the motor 40 includes at least a no-load state, a state to be loaded, and a loaded state. Among them, the no-load state is the state when the power tool 100 is initially started and has not yet been operated. The controller 60 can control the motor speed to increase and maintain it at a target low speed when the power tool 100 is in the no-load state. The state to be loaded is the state when the power tool 100 has been successfully started but has not yet been operated. The motor speed has reached the target low speed or the target low duty cycle. The controller 60 will control the motor speed to maintain it at the target low speed or the target low duty cycle when the power tool 100 is in the state to be loaded. The loaded state is the state when the power tool 100 has started to work. The controller 60 will control the motor speed to increase and maintain it at the target high speed when the power tool 100 is in the loaded state. In other words, in the technical solution of the present application, the controller 60 will comprehensively judge the state of the motor 40 and switch the corresponding motor control strategy to control the motor 40.

[0055] In some embodiments, the controller 60 dynamically adjusts the parameter threshold used when switching the motor control strategy according to the current ambient temperature to avoid problems such as motor 40 control failure and malfunction caused by ambient temperature changes. Figure 3 As shown, the controller 60 can first determine the parameter threshold corresponding to the ambient temperature based on the current ambient temperature from the temperature detection device 80, and then determine the current motor control strategy based on the numerical relationship between the current operating parameters from the parameter detection device 70 and the parameter threshold, and use the motor control strategy to regulate the motor speed and speed change trend, etc.

[0056] Correspondingly, refer to Figure 4 , Figure 4 This is a flow chart of the method for the controller 60 to control the motor 40 in the above embodiment. The method 400 for the controller 60 to control the motor 40 specifically includes:

[0057] S402, receiving the operating parameters of the motor 40 transmitted by the parameter detection device 70, and receiving the ambient temperature at the temperature measurement point transmitted by the temperature detection device 80;

[0058] S404, determining a parameter threshold corresponding to the ambient temperature according to the ambient temperature;

[0059] S406 , determining a current motor control strategy based on a numerical relationship between the operating parameter and the parameter threshold, and using the motor control strategy to control the motor 40 .

[0060] In the above embodiment, the parameter detection device 70 can detect and transmit one or more operating parameters, and the type and number of the operating parameters are not limited. For details, please refer to the relevant description above. The temperature detection device 80 can also detect and transmit the ambient temperature at one or more temperature measurement points, and the location and number of the temperature measurement points are not limited. For details, please refer to the relevant description above.

[0061] The controller 60 is provided with a data table for querying the corresponding parameter threshold value according to the ambient temperature, or a preset rule for obtaining the parameter threshold value according to the ambient temperature. For example, the controller 60 may be provided with a mapping table of the ambient temperature range and the parameter threshold value, or may be provided with a preset function for calculating the parameter threshold value from the ambient temperature. The controller 60 may query or calculate the corresponding parameter threshold value using the ambient temperature at a single temperature measuring point, or may analyze and convert the ambient temperature at multiple temperature measuring points and use the temperature obtained by the analysis and conversion to query or calculate the corresponding parameter threshold value, or may use the ambient temperature at multiple temperature measuring points to calculate the corresponding parameter threshold value. Among them, the parameter threshold values ​​corresponding to different ambient temperatures may be different. For example, the parameter threshold value when the environment is lower than the low temperature threshold value may be different from the ambient threshold value when the ambient temperature is higher than the high temperature threshold value, and there is no restriction on whether the ambient temperature and the parameter threshold value are positively correlated or negatively correlated.

[0062] The controller 60 selects a target strategy from a plurality of motor control strategies based on the numerical relationship between the operating parameter or the calculated value of the operating parameter and the parameter threshold value corresponding to the current ambient temperature. The operating parameter or the calculated value of the operating parameter includes a single operating parameter itself, a calculated value of a single operating parameter, and a calculated value of a plurality of operating parameters. In some embodiments, the controller 60 uses whether the operating parameter or the calculated value of the operating parameter exceeds the parameter threshold value corresponding to the current ambient temperature as a strategy switching condition. If the operating parameter or the calculated value of the operating parameter exceeds the current parameter threshold value, the first motor control strategy is adopted to control the motor 40; conversely, if the operating parameter or the calculated value of the operating parameter does not exceed the current parameter threshold value, the second motor control strategy is adopted to control the motor 40.

[0063] Among them, the second motor control strategy is the motor control strategy when the motor 40 is in a state to be loaded, and the controller 60 uses the second motor control strategy to control the motor 40 to maintain a target low speed or a target low duty cycle; the first motor control strategy is the motor control strategy when the motor 40 is in a loaded state, and the controller 60 uses the first motor control strategy to control the motor speed to rise and maintain it at a target high speed. There are many optional implementation methods for how the controller 60 controls the motor speed to rise or maintain. For example, the motor speed and the speed change process can be regulated by PWM duty cycle regulation or PI regulation, that is, the motor speed can be regulated to change linearly or nonlinearly according to the intended process, and to maintain the target duty cycle or target speed. In other embodiments, more numerical relationships can also be divided, for example, the difference between the operating parameter or its calculated value and the parameter threshold is greater than the first threshold, or less than or equal to the first threshold and greater than the second threshold, or less than or equal to the second threshold, so that the controller 60 can select from more motor control strategies based on the numerical relationship between the two.

[0064] In one implementation of the above embodiment, at the first moment, the temperature detection device 80 detects and transmits the current ambient temperature as the first ambient temperature. After receiving the first ambient temperature, the controller 60 can determine the first parameter threshold corresponding thereto, and compare the current first motor speed detected and transmitted by the parameter detection device 70 with the first parameter threshold. When the first motor speed is greater than the first parameter threshold, it is determined that the motor 40 is still in the waiting state, and the second motor control strategy is adopted to control the motor speed to maintain the target low speed or target low duty cycle. At the second moment, the temperature detection device 80 detects and transmits the second ambient temperature. After receiving the second ambient temperature, the controller 60 determines the second parameter threshold corresponding thereto, and compares the current second motor speed detected and transmitted by the parameter detection device 70 with the second parameter threshold. When the second motor speed is less than or equal to the second parameter threshold, it is determined that the motor 40 has entered the loaded state, and the first motor control strategy is adopted to control the motor speed to increase and maintain it at the target high speed.

[0065] Assuming that the second ambient temperature is higher than the first ambient temperature, the second parameter threshold is greater than the first parameter threshold, the first motor speed greater than the first parameter threshold may be less than the second parameter threshold, facing the same motor speed, the controller 60 at the second moment will use a first motor control strategy different from the first moment to control the motor 40, and the state of the motor 40 will be changed from the waiting state to the loaded state, which adapts to the phenomenon that the grease condensation between the gears is alleviated when the ambient temperature rises, causing the motor speed to increase. Correspondingly, the second motor speed less than the second parameter threshold may be greater than the first parameter threshold, facing the same motor speed, the controller 60 at the first moment will use a second motor control strategy different from the second moment to control the motor 40, and the state of the motor 40 will be changed from the loaded state to the waiting state, which adapts to the phenomenon that the grease condensation between the gears causes the motor speed to decrease when the ambient temperature drops, thereby effectively improving the temperature adaptability and sensitivity of the controller 60 in controlling the motor 40.

[0066] In some embodiments, the controller 60 also has a third motor control strategy, which is a motor control strategy when the motor 40 is in a no-load state. The controller 60 will use the third motor control strategy to control the motor speed to increase and maintain it at a target low speed or a target low duty cycle before the power tool 100 is started and the motor 40 enters a loading state.

[0067] In another implementation of the above embodiment, after the power tool 100 is started, the controller 60 uses the third motor control strategy to control the PWM duty cycle of the motor 40 to increase in the no-load state of the motor 40 until the target low duty cycle is reached, and the motor 40 enters the waiting state. Since the motor 40 is not loaded at this time, the increase in the PWM duty cycle is the increase in the motor speed. After the PWM duty cycle stabilizes at the target low duty cycle, the controller 60 can determine the no-load speed of the motor 40 at this time. Subsequently, the controller 60 can determine the corresponding parameter threshold value based on the no-load speed and the current ambient temperature, and switch the control strategy of the motor 40 by comparing the current motor speed with the parameter threshold value. Specifically, assuming that the controller 60 determines that the no-load speed of the motor 40 is Speed1 after the motor PWM duty cycle reaches and remains at the target low duty cycle, and the ambient temperature at a certain moment after the motor 40 enters the loading state is T1, then the parameter threshold used by the controller 60 to compare with the current motor speed can be F(Speed1)-f(T1), wherein F(Speed1) is a function positively correlated with Speed1, and f(T1) is a function negatively correlated with T1, that is, the higher the no-load speed and the higher the ambient temperature, the higher the corresponding parameter threshold. In other words, under this implementation, the parameters used to switch the motor control strategy are not only related to the current ambient temperature, but also to the stable speed of the motor 40 when it is unloaded. In fact, different supply voltages of the battery pack and different no-load target low duty cycles can affect the subsequent motor speed. The above implementation can effectively deal with related problems.

[0068] In some embodiments, considering that when the motor 40 is in a no-load state and has not yet entered the waiting-to-be-loaded state, operating parameters such as the motor speed are still in a changing state, this may affect the judgment of the switching conditions, the determination of the motor state, and the selection of the control strategy, resulting in misjudgment. Therefore, some of the technical solutions described above can be executed after the controller 60 determines that the motor 40 has entered the waiting-to-be-loaded state, and not executed when the motor 40 is still in the no-load state.

[0069] In some embodiments, the electric tool 100 has multiple working modes, including at least two speed regulation modes and one automatic sensing mode, and the operating member can be operated by the user to select the current target mode of the electric tool 100 from the above multiple working modes. When the current mode is the speed regulation mode, the controller 60 controls the motor 40 to run at a speed corresponding to the speed regulation mode, and when the current mode is the automatic sensing mode, the technical solutions for condition judgment and strategy switching related to motor control described above are executed.

[0070] In some embodiments, the controller 60 switches the motor 40 control strategy based on multiple operating parameters and their corresponding strategy switching conditions, rather than a single parameter and a single condition, to improve the sensitivity and accuracy of the controller 60 in the power tool 100 in controlling the motor 40. Figure 3 As shown, the controller 60 can detect whether each current operating parameter from the parameter detection device 70 satisfies the strategy switching condition corresponding to the operating parameter, and when any operating parameter satisfies the corresponding strategy switching condition, the first motor control strategy is used to control the motor 40, and when all operating parameters do not satisfy the corresponding strategy switching condition, the second motor control strategy is used to control the motor 40. It can be understood that in the above embodiment, the temperature detection device 80 may not be provided in the power tool 100.

[0071] Correspondingly, refer to Figure 5 , Figure 5 This is a flow chart of the method for the controller 60 to control the motor 40 in the above embodiment. The method 500 for the controller 60 to control the motor 40 specifically includes:

[0072] S502, receiving a plurality of operating parameters of the motor 40 transmitted by the parameter detection device 70;

[0073] S504, detecting whether each operating parameter satisfies a policy switching condition corresponding to the operating parameter, where the policy switching conditions corresponding to different operating parameters are different;

[0074] S506, when any operating parameter satisfies the corresponding strategy switching condition, the first motor control strategy is adopted to control the motor 40;

[0075] S508 : When all the operating parameters fail to satisfy the corresponding strategy switching conditions, the second motor control strategy is adopted to control the motor 40 .

[0076] In the above embodiment, the parameter detection device 70 detects and transmits at least two operating parameters, and the type and quantity thereof are not limited. For details, please refer to the above text. The controller 60 is provided with strategy switching conditions corresponding to each operating parameter. Specifically, the strategy switching condition corresponding to the operating parameter can be that the calculated value obtained from the operating parameter using the corresponding preset rule and the parameter threshold corresponding to the operating parameter have a certain specific numerical relationship. In some embodiments, the operating parameter satisfies the corresponding strategy switching condition for that the operating parameter or its calculated value exceeds the corresponding parameter threshold. Among them, the operating parameters and the strategy switching conditions can be a one-to-one correspondence, or they can not be a one-to-one correspondence. A strategy switching condition can be determined by a single operating parameter operation or by a combination of multiple operating parameters. However, when determining the motor state and switching the control strategy, the controller 60 will determine whether at least two strategy switching conditions are met.

[0077] In one implementation of the above embodiment, the parameter detection device 70 detects and transmits the three operating parameters of motor speed, bus voltage and freewheeling time. When the controller 60 receives the operating parameter of motor speed, it can detect whether the current motor speed is less than or equal to the motor speed threshold. When the controller 60 receives the two operating parameters of bus voltage and freewheeling time, it can detect whether the product of the current bus voltage and freewheeling time is greater than the voltage freewheeling threshold. Whether the current motor speed is less than or equal to the motor speed threshold, or the current bus voltage and freewheeling time product is greater than the voltage freewheeling threshold, the controller 60 can adopt the first motor control strategy to determine that the motor 40 has currently entered the loaded state, control the motor speed to increase and maintain it at the target high speed. When the current motor speed is greater than the motor speed threshold and the current bus voltage and freewheeling time product is less than or equal to the voltage freewheeling threshold, the controller 60 can adopt the second motor control strategy to determine that the motor 40 is still in the waiting state, and control the motor speed to maintain it at the target low speed or the target low duty cycle.

[0078] In another implementation of the above embodiment, the parameter detection device 70 detects and transmits two operating parameters, motor speed and bus current. When receiving the motor speed, the controller 60 can detect whether the difference between the inverse of the motor speed in this cycle and the inverse of the motor speed in the previous cycle is greater than the speed difference threshold. When receiving the bus current, it can detect whether the current bus current is greater than the loading current threshold. If any of the two conditions is met, the first motor control strategy is adopted, otherwise the second motor control strategy is adopted. It is understandable that the parameter detection device 70 can also detect and transmit more operating parameters, and the controller 60 can also judge more corresponding strategy switching conditions.

[0079] In some embodiments, the controller 60 also has a third motor control strategy used when the motor 40 is in an unloaded state. The controller 60 can use the third motor control strategy to control the motor speed to increase in the unloaded state of the motor before the power tool 100 is started and the motor 40 has not entered the waiting state, until the motor speed reaches the target low speed and then the motor speed is set to remain unchanged, and the motor 40 enters the waiting state. In this embodiment, the controller 60 can use PI regulation to control the motor speed in the unloaded and waiting states of the motor. The PI regulation is a closed-loop negative feedback regulation. After the controller 60 uses PI regulation to set the motor speed unchanged, the motor 40 can still be kept at the target speed in a dynamic balance even if it is loaded.

[0080] In one implementation of the above embodiment, in order to further improve the sensitivity and accuracy of the controller 60 in controlling the motor 40, the controller 60 can use the integral value of the function slope of the operating parameter with respect to time within a preset period to determine how to select the control strategy of the motor 40. In one example, considering that the bus current of the motor 40 will rise nonlinearly in order to maintain the target speed after being loaded under PI regulation, the controller 60 can detect whether the integral value of the function slope of the bus current of the motor 40 with respect to time within the corresponding preset period is greater than or equal to the current integral threshold. The function slope of the bus current with respect to time represents the change trend of the bus current of the motor 40 at each moment. If the bus current tends to increase at a moment, the function slope of the bus current with respect to time at that moment is a positive value. If the bus current tends to decrease at a moment, the function slope of the bus current with respect to time at that moment is a negative value. The integral value of the function slope of the bus current with respect to time within a cycle can represent the overall change trend of the bus current within the cycle. If the integral value is greater than or equal to the current integral threshold, the first motor control strategy is adopted to determine that the motor 40 has entered the loaded state, and the motor speed is controlled to increase and maintain at the target high speed; otherwise, the second motor control strategy is adopted to determine that the motor 40 is still in the loading state, and the motor speed is controlled to maintain at the target low speed.

[0081] In another example, considering that the PWM duty cycle of the motor 40 will increase nonlinearly to maintain the target speed after being loaded under PI regulation, the controller 60 can detect whether the integral value of the function slope of the PWM duty cycle of the motor 40 with respect to time in the corresponding preset period is greater than or equal to the duty cycle integral threshold. Similar to the principle of the previous text, the function slope of the PWM duty cycle with respect to time represents the change trend of the PWM duty cycle of the motor 40 at each moment, and the integral value of the function slope of the PWM duty cycle with respect to time in a cycle can represent the overall change trend of the PWM duty cycle in the cycle. If the integral value is greater than the duty cycle integral threshold, the first motor control strategy is adopted, otherwise the second motor control strategy is adopted.

[0082] In addition, considering that when the motor 40 is in a no-load state and has not yet entered a loaded state, operating parameters such as the bus current and the motor PWM duty cycle are still in a changing state, which may affect the judgment of the switching condition, the determination of the motor state, and the selection of the control strategy, resulting in misjudgment. In the above implementation method, the controller 60 can perform a comparison between the integral value and the threshold and switch the motor control strategy after the motor speed has exceeded the sensing speed threshold corresponding to the target low speed, and will not execute the relevant scheme before the motor speed has reached the sensing speed threshold. For example, the controller 60 can start the above-mentioned detection and switching after the motor speed has exceeded 95% of the target low speed.

[0083] In other embodiments, the controller 60 may use a third motor control strategy to control the motor PWM duty cycle to increase in the motor no-load state before the power tool 100 is started and the motor 40 has not entered the waiting state, until the motor speed reaches the target low duty cycle, and then set the motor PWM duty cycle to the target low duty cycle, and the motor 40 enters the waiting state. In this embodiment, the controller 60 may use PWM duty cycle adjustment to control the motor speed in the motor no-load and waiting state. The PWM duty cycle adjustment is affected by factors such as the power supply voltage and the motor load condition. After the controller 60 uses PWM duty cycle adjustment to set the motor PWM duty cycle unchanged, if loaded, the motor 40 cannot maintain the target duty cycle or target speed, the PWM duty cycle of the motor 40 decreases, and the motor speed decreases.

[0084] In one implementation of the above embodiment, in order to further improve the sensitivity and accuracy of the controller 60 in controlling the motor 40, the controller 60 can use the integral value of the function slope of the operating parameter with respect to time within a preset period to determine how to select the motor control strategy. Considering that the motor speed of the motor 40 will decrease nonlinearly after being loaded under PWM duty cycle regulation, the controller 60 can detect whether the integral value of the function slope of the motor speed of the motor 40 with respect to time within the corresponding preset period is less than or equal to the speed integral threshold. Similar to the principle of the previous text, the function slope of the motor speed with respect to time represents the change trend of the motor speed of the motor 40 at each moment, and the integral value of the function slope of the motor speed with respect to time within a period can represent the overall change trend of the motor speed within the period. If the integral value is less than or equal to the speed integral threshold, the first motor control strategy is adopted; otherwise, the second motor control strategy is adopted.

[0085] In some embodiments, the controller 60 periodically detects whether each operating parameter satisfies the corresponding strategy switching condition, and the period at which the controller 60 detects whether each operating parameter satisfies the corresponding strategy switching condition may be different. In some cases, the period at which the controller 60 detects whether each operating parameter satisfies the corresponding strategy switching condition may depend on the period at which the visual parameter detection device 70 transmits the operating parameter. In other cases, it may also depend on the characteristics of the operating parameter itself. Based on the above example, in one implementation, the controller 60 may periodically detect whether the current motor speed is less than or equal to the motor speed threshold according to a first preset period, and periodically detect whether the product of the current bus voltage and the freewheeling time is greater than the voltage freewheeling threshold according to a second preset period. The first preset period may be 5ms, and the second preset period may be 1ms.

[0086] In some embodiments, in addition to integrating multiple operating parameters to improve the comprehensiveness and accuracy of motor state determination and control strategy switching, the influence of ambient temperature considered above can be further combined to improve control failure, faults and other problems under special temperature environments. Figure 2As shown, the controller 60 will determine the strategy switching conditions corresponding to each operating parameter under the current ambient temperature based on the current ambient temperature detected and transmitted by the temperature detection device 80, wherein the controller 60 can periodically adjust the strategy switching conditions corresponding to each operating parameter based on the ambient temperature, and the period can be 1-10ms.

[0087] In some cases, the parameter thresholds used for comparison with the operating parameters or their calculated values ​​at different ambient temperatures may be different. In other cases, the calculation rules for the operating parameters used for comparison with the parameter thresholds at different ambient temperatures may also be different. In other words, in addition to the different policy switching conditions corresponding to different operating parameters, the policy switching conditions corresponding to the same operating parameter may also be different at different ambient temperatures. In some embodiments, in order to ensure the efficiency of the solution, the ambient temperature may only be distinguished between high and low temperatures, that is, an operating parameter has a policy switching condition at a high ambient temperature and a policy switching condition at a low ambient temperature.

[0088] The controller 60 detects whether the various operating parameters detected and transmitted by the parameter detection device 70 meet the strategy switching conditions corresponding to the operating parameters under the current ambient temperature, and adopts the first motor control strategy to control the motor speed to increase and maintain it at the target high speed after any operating parameter meets the corresponding strategy switching conditions, and adopts the second motor control strategy to control the motor speed to maintain it at the target low speed or the target low duty cycle when all operating parameters do not meet the corresponding strategy switching conditions.

[0089] Regarding the jigsaw 100a, a jigsaw 100a with an illumination assembly 200 and a control scheme thereof are described below. Figure 6 , Figure 7 As shown, the jigsaw 100a further includes a lighting assembly 200, which includes a lighting element 210 mounted near the clamping device 32 and a lighting operating member 220 mounted in the mounting groove 111 on the housing 10. The lighting element 210 is used to achieve a lighting function, and may include a lamp and a lampshade, for example, a single lamp bead and a transparent lampshade, or a ring-shaped shadowless lamp and a lampshade, etc. The lighting operating component 220 is assembled on the housing 10 in a manner that is convenient for assembly and disassembly and easy for maintenance. For example, it can include a switch PCB board 221 accommodated in the mounting groove 111 of the housing 10, and a switch panel 222 that cooperates with screws to fix the switch PCB board 221 and itself to the housing 10 and has a button 223 for the user to operate to turn on or off the lighting element 210. The switch PCB board 221 can be electrically connected to the lighting element 210 and the switch panel 222. When the button 223 on the switch panel 222 is operated by the user to turn on or off the lighting element 210, the switch PCB can correspondingly realize or assist in realizing the lighting and extinguishing of the lighting element 210.

[0090] In some embodiments, the controller 60 is electrically connected to the lighting element 210 and the lighting operating member 220. When the jig saw 100a is initially started and before the current operation begins, the controller 60 can read the lighting state of the lighting element 210 of the jig saw 100a during the previous operation, and control the lighting element 210 to turn on or off according to the lighting state. Generally, if the jig saw 100a performed a straight cut during the previous operation, its lighting element 210 is turned on. During the current operation, the controller 60 can light up the lighting element 210 according to the stored lighting state after power-on before starting the operation; if the jig saw 100a performed a reverse cut during the previous operation, its lighting element 210 is turned off. During the current operation, the controller 60 can keep the lighting element 210 off according to the stored lighting state before starting the operation after power-on. After the operating member 20 of the jigsaw 100a is operated and the saw blade 31 officially starts cutting, the controller 60 can detect whether the lighting operating member 220 is operated by the user to light up the currently extinguished lighting element 210, or turn off the currently lit lighting element 210. For example, the controller 60 can detect whether the button 223 on the switch panel 222 is operated and transmits a corresponding signal, and then light up or turn off the lighting element 210 accordingly if yes, and update the stored lighting state of the lighting element 220. In other embodiments, the controller 60 can also control the lighting element 210 to flash in a preset manner to provide a fault prompt when a fault is detected in the motor 40.

[0091] Regarding the jigsaw 100a, a jigsaw 100a with a protective cover 90 is described below. Figure 1 , Figure 2 and Figure 8As shown, the jigsaw 100a also includes a shield 90 made of a transparent material, which can enhance the dust collection effect, prevent wood chips from splashing, and allow the user to more conveniently observe the processing status. The shield 90 is rotatably connected to the housing 10 of the jigsaw 100a, and the housing 10 is provided with a first limiting groove 112, a second limiting groove 113 and a rotating connection groove 114. Specifically, a first limiting groove 112, a second limiting groove 113 and a rotating connection groove 114 can be respectively provided on the two side surfaces of the housing 10 closer to the saw blade 31, and they are located above the saw blade 31 and the clamping device 32. The first and second limiting grooves 112 and 113 may be rectangular grooves, the first limiting groove 112 may be arranged in a direction perpendicular to the straight line where the saw blade 31 is located, the second limiting groove 113 may be arranged in a direction where the guard 90 is turned outward and at least 90 degrees from the first limiting groove 112, and the rotation connection groove 114 may be arranged at the junction of the first limiting groove 112 and the second limiting groove 113. Correspondingly, a rotation protrusion 911 and a limiting rib position 912 are formed on both sides of the inner surface of the guard 90 located above the saw blade 31 and the clamping device 32, respectively. The rotation protrusion 911 corresponds to the shape of the rotation connection groove 114, and the limiting rib position 912 corresponds to the shape of the first limiting groove 112 and the second limiting groove 113.

[0092] The first limiting groove 112, the second limiting groove 113 and the rotation connection groove 114 on the housing 10 cooperate with the rotation protrusion 911 and the limiting rib 912 on the shield 90 to realize the rotation connection between the shield 90 and the housing 10. Figure 1 As shown, during the cutting operation of the saw blade 31 of the jigsaw 100a, the rotating protrusions 911 on both sides of the shield 90 are correspondingly embedded in the rotating connection grooves 114 on both sides of the housing 10 and are limited thereby, and the limiting ribs 912 on both sides of the shield 90 are correspondingly embedded in the first limiting grooves 112 on both sides of the housing 10 and are limited thereby, and the shield 90 forms a relatively closed protective space around the saw blade 31, thereby achieving the protective effects of increasing dust absorption and avoiding splashing, and can remain basically fixed without flipping when the workpiece vibrates. Figure 2 As shown, when replacing the saw blade 31 or checking the working condition, the rotating protrusions 911 on both sides of the shield 90 correspond to the rotating connecting grooves 114 on both sides of the casing 10 and are limited thereby. After the limiting ribs 912 on both sides of the shield 90 rotate, they correspond to the second limiting grooves 113 on both sides of the casing 10 and are limited thereby. The saw blade 31 is open around and is no longer blocked by the shield 90. Therefore, the user can easily replace the saw blade 31 or check the cutting path of the saw blade 31.

[0093] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. An electric tool comprising: Functional parts; A motor, used to drive the functional parts to operate; A power supply device, at least used to supply power to the motor; a parameter detection device, connected to the motor, and used to obtain a plurality of operating parameters of the motor and / or the power supply device; A controller, connected to the driving device and the parameter detection device, for controlling the operation of the motor; In which, the controller is configured to: detect whether each operating parameter satisfies the strategy switching condition corresponding to the operating parameter; when any operating parameter satisfies the corresponding strategy switching condition, adopt the first motor control strategy to control the motor; when none of the operating parameters satisfies the corresponding strategy switching condition, adopt the second motor control strategy to control the motor.

2. The electric tool according to claim 1, wherein: The operating parameters include at least two of the motor speed, bus current, bus voltage, phase voltage, PWM duty cycle, demagnetization time, and freewheeling time of the motor.

3. The electric tool according to claim 1, wherein: The electric tool also includes: a temperature detection device, connected to the controller, configured to obtain the ambient temperature at the temperature measurement point and transmit the ambient temperature to the controller; the controller is configured to: determine the strategy switching conditions corresponding to the various operating parameters at the ambient temperature based on the ambient temperature; detect whether the various operating parameters meet the strategy switching conditions corresponding to the operating parameters at the ambient temperature, and the strategy switching conditions corresponding to the same operating parameter at different ambient temperatures are different.

4. The electric tool according to claim 3, wherein: The ambient temperature is any one of the motor temperature, the housing temperature, and the MOS temperature of the electric tool.

5. The electric tool according to claim 1, wherein: The controller is configured to periodically detect whether each operating parameter satisfies a corresponding policy switching condition based on a detection period corresponding to each operating parameter.

6. The electric tool according to any one of claims 1 to 5, wherein: The controller is configured to: adopt the first motor control strategy to control the motor speed of the motor to increase and maintain it at a target high speed in a loaded state; adopt the second motor control strategy to control the motor speed of the motor to maintain it at a target low speed in a ready-to-load state, or set the PWM duty cycle of the motor to a target low duty cycle in a ready-to-load state.

7. The electric tool according to claim 6, wherein: The controller is configured to: use the operating parameter or the calculated value of the operating parameter exceeding the parameter threshold corresponding to the operating parameter as the strategy switching condition; or use the operating parameter or the calculated value of the operating parameter exceeding the parameter threshold corresponding to the operating parameter at the ambient temperature as the strategy switching condition.

8. The electric tool according to claim 6, wherein: The controller is further configured to: before the motor enters the waiting-to-load state, use a third motor control strategy to control the motor speed of the motor to increase in a no-load state, and then set the motor speed unchanged after the motor speed reaches a target low speed, and the motor enters the waiting-to-load state; If the integral value of the function slope of the bus current of the motor with respect to time within a preset period is greater than or equal to the corresponding current integral threshold, the first motor control strategy is adopted to control the motor.

9. The electric tool according to claim 6, wherein: The controller is further configured to: before the motor enters the waiting-to-load state, use a third motor control strategy to control the motor speed of the motor to increase in a no-load state, and then set the motor speed unchanged after the motor speed reaches a target low speed, and the motor enters the waiting-to-load state; If the integral value of the slope of the function of the PWM duty cycle of the motor with respect to time within a preset period is greater than or equal to the corresponding duty cycle integral threshold, the first motor control strategy is adopted to control the motor.

10. The electric tool according to claim 6, wherein: The controller is further configured to: before the motor enters the waiting-to-be-loaded state, use a third motor control strategy to control the PWM duty cycle of the motor to increase in a no-load state, until the PWM duty cycle reaches a target low duty cycle, then set the PWM duty cycle unchanged, and the motor enters the waiting-to-be-loaded state; If the integral value of the slope of the function of the motor speed with respect to time within a preset period is less than or equal to the corresponding speed integral threshold, the first motor control strategy is adopted to control the motor.

11. A method for controlling an electric tool, comprising: The controller of the electric tool receives a plurality of operating parameters of the motor transmitted by the parameter detection device; The controller detects whether each operating parameter satisfies a strategy switching condition corresponding to the operating parameter; When any operating parameter satisfies a corresponding strategy switching condition, the motor is controlled using a first motor control strategy; When none of the operating parameters satisfies the corresponding strategy switching conditions, the second motor control strategy is adopted to control the motor.

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