Electric tool

Abstract

The invention discloses an electric tool, which comprises a battery pack for providing electric energy; the motor comprises a rotor and a three-phase stator winding; a drive circuit having a plurality of semiconductor switching elements; the parameter detection module is used for detecting working parameters when the motor operates; the controller is at least electrically connected with the battery pack, the driving circuit and the motor; the controller is configured to obtain parameters of the electric tool; acquiring a corresponding preset parameter range and a preset conduction angle according to the electric tool parameter and a preset electric tool parameter threshold value; and controlling the working parameters to be within a preset parameter range, so that the stator winding is switched to a preset conduction angle corresponding to the preset parameter range. By the adoption of the technical scheme, the electric tool is not prone to halt and good in cutting hand feeling.

Description

Technical Field

[0001] The present application relates to the field of power tools, and particularly to a power tool. Background Art

[0002] In order to increase the motor speed throughout the entire speed range, a lead angle and an extended angle are usually introduced in the motor control of a sensorless motor to increase the conduction angle of the winding and enhance the field weakening of the winding, thereby increasing the motor speed. That is to say, the three-phase stator windings of the motor no longer simply conduct and commutate in pairs, but also include the process of conducting and commutating in threes, so as to increase the conduction angle of the motor winding.

[0003] The parameters of the power tool and the corresponding conduction angle of the motor winding will affect the cutting feel of the power tool. When the conduction angle of the motor winding corresponding to the parameters of the power tool is set unreasonably, the power tool is prone to frequent protection and shutdown, resulting in poor cutting feel.

[0004] This section provides background information related to the present application, and such background information is not necessarily prior art. Summary of the Invention

[0005] To solve the deficiencies of the prior art, the purpose of the present application is to provide a power tool that is not easily shut down and has a better cutting feel.

[0006] To achieve the above objective, the present application adopts the following technical solution: A power tool, comprising:

[0007] A battery pack that provides electrical energy; a motor, including a rotor and three-phase stator windings; a drive circuit having a plurality of semiconductor switching elements; a parameter detection module for detecting the operating parameters during the operation of the motor; a controller electrically connected to at least the battery pack, the drive circuit, and the motor; the controller is configured to: obtain the power tool parameters; obtain the corresponding preset parameter range and preset conduction angle according to the power tool parameters and the preset power tool parameter threshold; control the operating parameters within the preset parameter range so that the stator windings are switched to the preset conduction angle corresponding to the preset parameter range.

[0008] In some embodiments, the controller is configured to: control the operating parameters within the preset parameter range so that the stator windings are switched to the corresponding conduction mode corresponding to the preset parameter range, and based on the conduction mode, control the stator windings to be switched to the corresponding preset conduction angle.

[0009] In some embodiments, during the operation of the motor, the stator windings have a first conduction mode of two-phase winding commutation conduction and a second conduction mode of three-phase winding commutation conduction.

[0010] In some embodiments, the operating parameters include the phase voltage of the floating phase during the commutation process of the stator windings and the phase voltage of the conducting phase of the stator windings.

[0011] In some embodiments, the power tool parameter includes the battery pack voltage, and the preset power tool parameter threshold includes a first voltage threshold and / or a second voltage threshold.

[0012] In some embodiments, when the battery pack voltage is greater than the first voltage threshold and less than the second voltage threshold, the preset parameter range is proportional to the battery pack voltage; when the battery pack voltage is greater than or equal to the second voltage threshold, the preset parameter range is a first parameter range.

[0013] In some embodiments, when the preset parameter range is proportional to the battery pack voltage, the conduction mode is a second conduction mode, and the preset conduction angle is proportional to the battery pack voltage; when the preset parameter range is the first parameter range, the conduction mode is a second conduction mode, and the preset conduction angle is a first conduction angle.

[0014] In some embodiments, when the battery pack voltage is less than or equal to the first voltage threshold, the preset parameter range is 0 or the preset parameter range is a second parameter range, and the second parameter range is less than the first parameter range.

[0015] In some embodiments, when the preset parameter range is 0, the conduction mode is a first conduction mode, and the preset conduction angle is 120°; when the preset parameter range is the second parameter range, the conduction mode is a second conduction mode, and the preset conduction angle is a second conduction angle.

[0016] In some embodiments, when the battery pack voltage is less than or equal to the first voltage threshold or the second voltage threshold, the preset parameter range is 0 or the preset parameter range is a second parameter range; when the battery pack voltage is greater than the first voltage threshold or the second voltage threshold, the preset parameter range is a first parameter range; wherein, the second parameter range is less than the first parameter range.

[0017] In some embodiments, the power tool parameter includes the battery pack capacity, and the preset power tool parameter threshold includes a first capacity threshold and / or a second capacity threshold.

[0018] In some embodiments, when the battery pack capacity is less than or equal to the first capacity threshold, the preset parameter range is 0 or the preset parameter range is a third parameter range; when the battery pack capacity is greater than the first capacity threshold and less than the second capacity threshold, the preset parameter range is proportional to the battery pack capacity; when the battery pack capacity is greater than or equal to the second capacity threshold, the preset parameter range is a fourth parameter range.

[0019] In some embodiments, when the preset parameter range is 0, the conduction mode is a first conduction mode, and the preset conduction angle is 120°; when the parameter range is the third parameter range, the conduction mode is a second conduction mode, and the preset conduction angle is a third conduction angle.

[0020] In some embodiments, when the preset parameter range is proportional to the battery pack capacity, the conduction mode is the second conduction mode, and the preset conduction angle is proportional to the battery pack voltage; when the preset parameter range is the fourth parameter range, the conduction mode is the second conduction mode, and the preset conduction angle is the fourth conduction angle.

[0021] In some embodiments, the power tool parameters include the battery pack temperature or the power tool temperature, and the preset power tool parameter thresholds include the first temperature threshold and / or the second temperature threshold, the third temperature threshold and / or the fourth temperature threshold.

[0022] In some embodiments, when the battery pack temperature is less than or equal to the first temperature threshold, the preset parameter range is the fifth parameter range, and the preset conduction angle is the fifth conduction angle; when the battery pack temperature is greater than the first temperature threshold and less than the second temperature threshold, the preset parameter range is inversely proportional to the battery pack temperature, and the preset conduction angle is inversely proportional to the battery pack temperature; when the battery pack temperature is greater than or equal to the second temperature threshold, the preset parameter range is the sixth parameter range, and the preset conduction angle is the sixth conduction angle; wherein, the sixth parameter range is less than the fifth parameter range, and the sixth conduction angle is less than the fifth conduction angle.

[0023] In some embodiments, when the power tool temperature is less than or equal to the third temperature threshold, the preset parameter range is the seventh parameter range, and the preset conduction angle is the seventh conduction angle; when the power tool temperature is greater than the third temperature threshold and less than the fourth temperature threshold, the preset parameter range is inversely proportional to the power tool temperature, and the preset conduction angle is inversely proportional to the power tool temperature; when the power tool temperature is greater than or equal to the fourth temperature threshold, the preset parameter range is the eighth parameter range, and the preset conduction angle is the eighth conduction angle; wherein, the eighth parameter range is less than the seventh parameter range, and the eighth conduction angle is less than the seventh conduction angle.

[0024] In some embodiments, when the stator winding is in the second conduction mode, the conduction angle of the stator winding conduction is greater than 120° and less than 180°.

[0025] In some embodiments, a power tool includes: a battery pack that provides electrical energy; a motor that includes a rotor and a three-phase stator winding; a drive circuit that has a plurality of semiconductor switching elements; a parameter detection module that is configured to detect operating parameters during motor operation; a controller that is electrically connected to at least the battery pack, the drive circuit, and the motor; wherein, during motor operation, the stator winding has a first conduction mode in which two-phase windings conduct in sequence and a second conduction mode in which three-phase windings conduct in sequence; the controller is configured to: obtain the temperature of the battery pack; control the stator winding to be in the first conduction mode or the second conduction mode according to the temperature of the battery pack.

[0026] In some embodiments, a power tool includes: a battery pack that provides electrical energy; an electric motor including a rotor and a three-phase stator winding; a drive circuit having a plurality of semiconductor switching elements; a parameter detection module configured to detect operating parameters of the electric motor during operation; and a controller electrically connected to at least the battery pack, the drive circuit, and the electric motor. The controller is configured to: obtain power tool parameters; obtain a corresponding preset parameter range based on the power tool parameters and preset power tool parameter thresholds; and control the operating parameters within the preset parameter range so that the stator winding switches to a conduction mode corresponding to the preset parameter range.

[0027] The advantages of the present application are as follows: By controlling the operating parameters of the electric motor within the preset parameter range, the conduction angle of the power tool is made the preset conduction angle. When the power tool parameters change, the conduction angle of the motor winding can be controlled to be a reasonable conduction angle, thereby providing a power tool that is not easily shut down and has a better cutting feel. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a structural diagram of a power tool provided by an embodiment;

[0029] Figure 2 is a circuit block diagram of a power tool provided by an embodiment;

[0030] Figure 3 is a schematic diagram of the commutation of the motor windings in a pairwise conduction cycle provided by an embodiment;

[0031] Figure 4 is a schematic diagram of the commutation of the motor windings in a three-by-three conduction cycle provided by an embodiment;

[0032] Figure 5 is a schematic diagram showing the relationship between the battery pack voltage and the parameter range change and the relationship with the preset conduction angle provided by an embodiment;

[0033] Figure 6 is a schematic diagram showing the relationship between the battery pack voltage and the parameter range change and the relationship with the preset conduction angle provided by another embodiment;

[0034] Figure 7 is a schematic diagram showing the relationship between the battery pack voltage and the parameter range change and the relationship with the preset conduction angle provided by another embodiment;

[0035] Figure 8 is a schematic diagram showing the relationship between the battery pack temperature and the parameter range change and the relationship with the preset conduction angle provided by an embodiment;

[0036] Figure 9 is a schematic diagram showing the relationship between the battery pack temperature and the parameter range change and the relationship with the preset conduction angle provided by another embodiment;

[0037] Figure 10 It is a schematic diagram showing the relationship between the temperature of another battery pack provided by an embodiment and the change of parameters, as well as the relationship between the preset conduction angle. Specific embodiments

[0038] Before explaining any embodiment of the present application in detail, it should be understood that the present application is not limited to the structural details and component arrangements described in the following description or shown in the above drawings.

[0039] In the present application, the terms "comprising", "including", "having" or any other variation thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device comprising a series of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article or device. Without further limitation, an element defined by the phrase "comprising a..." does not exclude the presence of additional identical elements in the process, method, article or device comprising such element.

[0040] In the present application, the term "and / or" describes the association relationship of associated objects and indicates that three relationships may exist. For example, A and / or B may represent three situations: A exists alone, A and B exist simultaneously, and B exists alone. In addition, the character " / " in the present application generally represents an "and / or" relationship between the associated objects before and after.

[0041] In the present application, the terms "connect", "combine", "couple", "mount" may be direct connection, combination, coupling or mounting, or may be indirect connection, combination, coupling or mounting. Among them, by way of example, direct connection means that two parts or components are connected together without the need for an intermediate member, and indirect connection means that two parts or components are respectively connected to at least one intermediate member, and these two parts or components are connected through the intermediate member. In addition, "connection" and "coupling" are not limited to physical or mechanical connection or coupling, and may include electrical connection or coupling.

[0042] In this application, those of ordinary skill in the art will understand that relative terms used in connection with quantities or conditions (such as "about", "approximately", "substantially", etc.) are intended to include the stated value and have the meaning indicated by the context. For example, such relative terms include at least the degree of error associated with the measurement of a particular value, tolerances resulting from manufacturing, assembly, use in relation to a particular value, etc. Such terms should also be considered to disclose a range defined by the absolute values of two endpoints. Relative terms may refer to plus or minus a certain percentage (such as 1%, 5%, 10% or more) of the indicated value. Numerical values without the use of relative terms should also be disclosed as specific values with tolerances. In addition, when expressing relative angular positional relationships (such as substantially parallel, substantially perpendicular), "substantially" may refer to plus or minus a certain number of degrees (such as 1 degree, 5 degrees, 10 degrees or more) from the indicated angle.

[0043] In this application, those of ordinary skill in the art will understand that the functions performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the functions performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0044] In this application, the orientation terms such as "upper", "lower", "left", "right", "front", "rear", etc. are described based on the orientation and positional relationship shown in the drawings, and should not be construed as a limitation on the embodiments of this application. In addition, in the context, it should also be understood that when it is mentioned that one element is connected "above" or "below" another element, it can not only be directly connected "above" or "below" another element, but also be indirectly connected "above" or "below" another element through an intermediate element. It should also be understood that orientation terms such as the upper side, lower side, left side, right side, front side, rear side, etc. not only represent the positive orientation, but can also be understood as the side orientation. For example, the lower side can include directly below, lower left, lower right, lower front, and lower rear, etc.

[0045] In this application, the terms "controller", "processor", "central processor", "CPU", "MCU" can be used interchangeably. When using the units "controller", "processor", "central processor", "CPU", or "MCU" to perform specific functions, unless otherwise specified, these functions can be performed by a single one of the above units or multiple of the above units.

[0046] In this application, for the terms "device", "module", or "unit" to achieve a specific function, they can be implemented in the form of hardware or software.

[0047] 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 devices (such as a controller, a processor, etc.).

[0048] The power tools applicable to the technical solution of this application include any power tools that can adopt the brushless and sensorless electronic control method, such as grinding tools, electric drills, circular saws, reciprocating saws, miter saws, etc. As long as other types of power tools can adopt the substantial content of the technical solution disclosed below, they will fall within the protection scope of this application.

[0049] In this application, the motor winding or the stator winding or the winding all represent the metal winding in the motor. Without special instructions, the above names for the metal winding can be used interchangeably.

[0050] In the embodiments of this application, referring to Figure 1 Taking the impact power tool as an example, the power tool 100 at least includes a housing 10, a motor 11 inside the housing, a power supply 12, a switch 13, a working head 14, etc. The motor 11, a control circuit board, and a transmission structure (not shown) are built in the housing 10. The housing 10 also forms a gripping portion 101 for the user to hold.

[0051] Referring to Figure 2 As shown in the circuit block diagram of the power tool, the drive system of the motor 11 can at least include a drive circuit 20, a power supply 12, a controller 21, and a parameter detection module 22.

[0052] In some embodiments, the motor 11 is a brushless DC motor (BLDC). In some embodiments, the motor 11 is a sensorless BLDC. In some embodiments, the motor 11 is a sensor BLDC. In this application, the brushless DC motor can be an inner rotor motor or an outer rotor motor. The motor 11 at least includes three-phase stator windings A, B, and C, and the three-phase windings can be star-connected or delta-connected.

[0053] In some embodiments, the power supply 12 can be selected as an AC power supply, that is, 120V or 220V AC mains can be accessed through the power supply interface. In some embodiments, the power supply 12 can be selected as a battery pack. The battery pack can be composed of a group of battery units. For example, the battery units can be connected in series into a single power branch to form a 1P battery pack. In this application, the battery pack is taken as an example of the power supply 12 for specific description. The output voltage of the battery pack is changed through a specific power control module, such as a DC-DC module, to output a supply voltage suitable for the drive circuit 20, the motor 11, etc., and supply power to them. Those skilled in the art can understand that the DC-DC module is a mature circuit structure and can be selected accordingly according to the specific parameter requirements of the power tool.

[0054] The drive circuit 20 is electrically connected to the stator windings A, B, and C of the motor 11, and is used to transfer the current from the power supply 12 to the stator windings A, B, and C to drive the motor 11 to rotate. In some embodiments, the drive circuit 20 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, and Q6. The gate terminal of each switching element is electrically connected to the controller 21 for receiving a control signal from the controller 21. The drain or source of each switching element is connected to the stator windings A, B, and C of the motor 11. The switching elements Q1-Q6 receive control signals from the controller 21 to change their respective conduction states, thereby changing the current applied to the stator windings A, B, and C of the motor 11 by the power supply 12. In some embodiments, the drive circuit 20 may be a three-phase bridge driver circuit including six controllable semiconductor power devices (such as FET, BJT, IGBT, etc.). It can be understood that the above switching elements may also be any other type of solid-state switch, such as insulated gate bipolar transistor (IGBT), bipolar junction transistor (BJT), etc.

[0055] To drive Figure 2 the shown motor 11 to rotate, the drive circuit 20 generally has at least six drive states, and each switching of the drive state corresponds to a commutation action of the motor. As Figure 3 shown, the horizontal axis represents the commutation points of the stator within a 360° cycle, and the vertical axis represents the back electromotive force of the three-phase windings. Figure 3 In the figure, the motor commutes once every 60° rotation of the rotor, and the interval from one commutation of the motor to the next commutation is defined as the commutation interval. As can be seen from Figure 3 it, within a 360° commutation cycle, there are six commutation beats, and the three-phase windings of the motor are all conducting for 120°, that is, the conduction angle is 120°. Usually, the commutation method of the stator windings shown in Figure 3 is called the commutation conduction of two-phase windings, that is, the way of conducting two by two. In the two-by-two conduction method, the weak magnetic field ability of the motor stator winding is not high, and the improvement effect of the motor speed is not obvious.

[0056] Generally, in order to improve the weak magnetic field ability and increase the motor speed, the conduction angle is increased, for example, the conduction angle is increased to be greater than 120°. To increase the conduction angle, the equivalent voltage applied to the stator winding is usually increased. For a three-phase motor, increasing the conducting phase of the stator winding means changing from the commutation conduction of two-phase windings to the commutation conduction of three-phase windings, that is, switching from two-by-two conduction to three-by-three conduction. Exemplarily, commutation is performed once every 30° rotation of the rotor, that is, 12 commutation actions are performed within a 360° commutation cycle, which can ensure that all three-phase windings of the motor are conducting during the commutation process, so that the conduction angle is greater than 120°, for example, the conduction angle is 150°. As Figure 4 shown, when the motor commutes every 30°, the stator winding switches from two-by-two conduction to three-by-three conduction, and switches from three-by-three conduction to two-by-two conduction during the next commutation. Compared withFigure 4 and Figure 3 It can be seen that the commutation of the stator winding is advanced by 30°. Therefore, relative to the original conduction angle, the conduction angle of the stator winding is increased by 30° to 150°.

[0057] In some embodiments, as Figure 2 shown, the power tool 100 includes a parameter detection module 22 that can detect the operating parameters during the operation of the motor. For example, during the commutation of the motor stator winding, the phase voltage of the floating phase or the phase voltage or phase current when the stator winding is conducting, etc. The so-called floating phase is the non-conducting phase. For example, when two phases conduct pairwise and the C phase does not conduct when the AB phases conduct, then the C phase is the floating phase. It can be understood that the phase voltage of the conducting phase is constant, and the phase voltage of the floating phase changes at a certain rate between the lowest voltage and the highest voltage during conduction.

[0058] Exemplarily, the power tool 100 has multiple parameters. Different parameters of the power tool 100 correspond to different conduction angles of the corresponding stator winding. If the conduction angle of the stator winding set based on the parameters of the power tool 100 is inappropriate, the power tool 100 is likely to enter the protection state, affecting the cutting feel. To ensure that the power tool 100 has a good cutting feel when using different parameters, usually Figure 4 the method shown is used to control the commutation of the motor stator winding conduction, that is, the pairwise conduction and three-phase conduction methods are used. By switching the conduction angle of the stator winding, the power tool 100 is prevented from entering the protection state, thereby ensuring the cutting feel of the power tool 100.

[0059] In some embodiments, the controller 21 can obtain the parameters of the power tool 100, and then obtain the corresponding preset parameter range according to the parameters of the power tool 100 and the preset parameter threshold of the power tool 100. Furthermore, the operating parameters during the operation of the motor 11 are controlled within the preset parameter range, so that the stator winding is switched to the corresponding conduction mode and preset conduction angle of the preset parameter range. Different conduction modes correspond to different conduction angles. Among them, the stator winding includes a first conduction mode in which two-phase windings commutate and conduct, and a second conduction mode in which three-phase windings commutate and conduct. The conduction angle of the stator winding corresponding to the first conduction mode is 120°, and the conduction angle of the stator winding corresponding to the second conduction mode is greater than 120° and less than 180°. Among them, the parameters of the power tool 100 can be the parameters of the battery pack or the parameters of the power tool 100 itself. The parameters of the battery pack include the battery pack voltage, battery pack capacity, and battery pack temperature. The parameters of the power tool 100 itself include the temperature of the power tool 100. In addition, the parameters of the battery pack and the parameters of the power tool 100 itself can also be other parameters, which are not limited in this application. Among them, the operating parameters of the motor 11 include the phase voltage of the floating phase during the commutation of the stator winding and the phase voltage of the conducting phase of the stator winding.

[0060] It can be understood that in order for the power tool 100 to have a good cutting feel at different parameters, for each parameter of the power tool 100, when the value of each parameter is different, the conduction angle of the stator winding is also different. This requires reasonably setting the switching timing from the first conduction mode to the second conduction mode so that the conduction angle of the stator winding can change adaptively when each parameter of the power tool 100 changes.

[0061] In this embodiment, the controller 21 can control the operating parameters of the motor 11 before the motor 11 starts, that is, control the operating parameters of the motor 11 based on a preset parameter range, so that the stator winding is switched to the corresponding conduction mode, and further the stator winding is switched to the corresponding conduction angle. Among them, when the controller 21 controls the operating parameters to be within the preset parameter range, it controls the stator winding to be switched to the second conduction mode. That is to say, if the operating parameters of the motor 11 are within the preset parameter range, the conduction mode of the stator winding is switched to the three-three conduction mode. If the operating parameters of the motor 11 are not within the preset parameter range, the conduction mode of the stator winding is switched to the two-two conduction mode.

[0062] In some embodiments, the controller 21 can calculate the ratio of the phase voltage of the floating phase to the phase voltage of the conducting phase during the commutation process of the stator winding. When this ratio is within the preset parameter range, it controls the stator winding to be switched from two-two conduction to three-three conduction. Assuming that the phase voltage of the floating phase is V1 and the phase voltage of the conducting phase is V2, when the value of V1 / V2 is within the preset parameter range, it controls the stator winding to switch the conduction mode to three-three conduction. In some embodiments, the preset parameter range can be a numerical interval, such as a numerical interval less than 1, such as the numerical interval [0.1, 0.8] or (0.1, 0.8) or [0.2, 0.8] or (0.2, 0.8) or [0.3, 0.8] or (0.3, 0.8) or [0.3, 0.7] or (0.3, 0.7) or [0.2, 0.7] or (0.2, 0.7) or [0.3, 0.6] or (0.3, 0.6) or [0.3, 0.5] or (0.3, 0.5) or [0.3, 0.4] or (0.3, 0.4) or [0.4, 0.7] or (0.4, 0.7) or [0.5, 0.7] or (0.5, 0.7), etc.

[0063] In some embodiments, when the parameter of the power tool 100 is the battery pack voltage, after the switch of the power tool 100 is turned on and before the motor 11 starts, the controller 21 can detect the voltage of the battery pack and set a preset parameter range according to the magnitude of the battery pack voltage. Then, after the motor 11 starts, the controller 21 can control the stator winding to switch to a conduction mode and conduction angle that match the voltage of the battery pack. Generally, when the battery pack voltage is relatively small, the set preset parameter range is small, that is, the preset parameter range is narrowed, and the corresponding preset conduction angle is also small. When the battery pack voltage is large, the preset parameter range will be increased, and the corresponding preset conduction angle is also large. For example, when the battery pack voltage is large, the preset parameter range is (0.3, 0.7), and the preset conduction angle is 150°. When the value of V1 / V2 is within (0.3, 0.7), the controller 21 controls the winding to switch the conduction mode to three-phase three-conduction, and controls the conduction angle to be 150°. When the battery pack voltage is relatively small, the preset parameter range is (0.4, 0.7), and the preset conduction angle is 130°. When the value of V1 / V2 is within (0.6, 0.7), the controller 21 controls the stator winding to switch the conduction mode to three-phase three-conduction, and controls the conduction angle to be 130°. When the battery pack voltage is very small, the preset parameter range is 0, that is, there is no preset parameter range, the value of V1 / V2 will not be within the preset parameter range, and the controller 21 controls the stator winding to switch the conduction mode to two-phase two-conduction, and the conduction angle is 120°. Or when the battery pack voltage is very small, the preset parameter range is very small, which is (0.1, 0.2), and the preset conduction angle is 122°. When the value of V1 / V2 is within (0.1, 0.2), the controller 21 controls the stator winding to switch the conduction mode to three-phase three-conduction, and controls the conduction angle to be 122°.

[0064] In some embodiments, such as Figure 5As shown, the preset parameter thresholds corresponding to the battery pack voltage for the power tool 100 include a first voltage threshold A and a second voltage threshold B. When the battery pack voltage is less than or equal to the first voltage threshold A, the corresponding preset parameter range is 0, and the preset conduction angle is 120°. Then, after the motor 11 starts, the value of V1 / V2 will not be within the preset parameter range, and the controller 21 controls the switching conduction mode of the stator windings to two-by-two conduction, with a conduction angle of 120°. When the battery pack voltage is greater than or equal to the second voltage threshold B, the corresponding preset parameter range is the first parameter range, which has a larger range, and the preset conduction angle is the first conduction angle. Then, after the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the first parameter range, causing the switching conduction mode of the stator windings to three-by-three conduction, and controlling the conduction angle of the stator windings to be the first conduction angle. When the battery pack voltage is greater than the first threshold A and less than the second threshold B, that is, when the battery pack voltage is between the first voltage threshold A and the second voltage threshold B, the corresponding preset parameter range is a variable range, which is proportional to the battery pack voltage, and the preset conduction angle is proportional to the battery pack voltage, and the range of the preset conduction angle is between 120° and the first conduction angle. For example, when the battery pack voltage is between the first voltage threshold A and the second voltage threshold B, a voltage value corresponds to a preset parameter range or a preset conduction angle, or the voltage values between the first voltage threshold A and the second voltage threshold B are further divided into stages, and the voltage within each stage corresponds to a preset parameter range or a preset conduction angle. Then, after the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the corresponding preset parameter range, causing the switching conduction mode of the stator windings to three-by-three conduction, and making the conduction angle of the stator windings the corresponding conduction angle proportional to the voltage. In this embodiment, the unit or parameter of the first voltage threshold A or the second voltage threshold B representing the battery pack voltage size is not limited here. For battery packs of different capacities, the sizes of the first voltage threshold A and the second voltage threshold B can be the same or different, which is not limited in this application.

[0065] In some embodiments, as Figure 6 shown, when the battery pack voltage is less than or equal to the first voltage threshold A, the corresponding preset parameter range can also be the second parameter range, which has a smaller range, and the corresponding preset conduction angle is the second conduction angle. Then, after the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the second parameter range, causing the switching conduction mode of the stator windings to three-by-three conduction, and controlling the conduction angle of the stator windings to be the second conduction angle. Among them, the second parameter range is smaller than the first parameter range, and the second conduction angle is smaller than the first conduction angle. Among them, the values of the second conduction angle and the first conduction angle are determined according to empirical values.

[0066] In some embodiments, as Figure 7As shown, the preset parameter threshold of the power tool 100 corresponding to the battery pack voltage only includes the first voltage threshold A (or the second voltage threshold B). When the battery pack voltage is less than or equal to the first voltage threshold A, the corresponding preset parameter range is 0, and the preset conduction angle is 120°. Then, after the motor 11 starts, the controller 21 controls the stator winding to switch the conduction mode to two-by-two conduction, and the conduction angle is 120°. When the battery pack voltage is greater than the first voltage threshold A, the corresponding preset parameter range is the first parameter range, and the preset conduction angle is the first conduction angle. Then, after the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the first parameter range, so that the stator winding switches the conduction mode to three-by-three conduction, and controls the conduction angle of the stator winding to be the first conduction angle. In addition, when the battery pack voltage is less than or equal to the first voltage threshold A, the corresponding preset parameter range can also be the second parameter range, and the preset conduction angle can also be the second conduction angle.

[0067] In some embodiments, when the parameter of the power tool 100 is the battery pack capacity, after the switch of the power tool 100 is turned on and before the motor 11 starts, the controller 21 can detect the capacity of the battery pack through communication with the battery pack, or the battery pack actively transmits its own capacity information to the controller 21. The controller 21 sets the preset parameter range according to the size of the battery pack capacity. Then, after the motor 11 starts, the controller 21 can control the stator winding to switch to a conduction mode and a conduction angle that match the battery pack capacity. The preset parameter range set by the battery pack capacity is similar to the battery pack voltage and will not be elaborated here.

[0068] In some embodiments, the preset power tool parameter thresholds corresponding to the battery pack capacity include a first capacity threshold C and a second capacity threshold D. When the battery pack capacity is less than or equal to the first capacity threshold C, the corresponding preset parameter range is 0, and the preset conduction angle is 120°. Then, after the motor 11 is started, the value of V1 / V2 will not be within the preset parameter range, and the controller 21 controls the conduction mode of the stator windings to switch to two-by-two conduction, with a conduction angle of 120°. Alternatively, when the battery pack capacity is less than or equal to the first capacity threshold C, the corresponding preset parameter range is the third parameter range, and the third parameter range is relatively small, and the preset conduction angle is the third conduction angle. Then, after the motor 11 is started, the controller 21 controls the value of V1 / V2 to be within the third parameter range, so that the conduction mode of the stator windings switches to three-by-three conduction, and the conduction angle of the stator windings is controlled to be the third conduction angle. When the battery pack capacity is greater than the first capacity threshold C and less than the second capacity threshold D, the corresponding preset parameter range is proportional to the battery pack capacity. Then, after the motor 11 is started, the controller 21 controls the value of V1 / V2 to be within the corresponding preset parameter range, so that the conduction mode of the stator windings switches to three-by-three conduction, and the conduction angle of the stator windings is the corresponding conduction angle proportional to the capacitance. Among them, the specific content of the preset parameter range being proportional to the battery pack capacity is similar to that of the preset parameter range being proportional to the battery pack voltage, which will not be elaborated here. When the battery pack capacity is greater than the second capacity threshold D, the corresponding preset parameter range is the fourth parameter range, and the fourth parameter range is relatively large, and the preset conduction angle is the fourth conduction angle. Then, after the motor 11 is started, the controller 21 controls the value of V1 / V2 to be within the fourth parameter range, so that the conduction mode of the stator windings switches to three-by-three conduction, and the conduction angle of the stator windings is controlled to be the fourth conduction angle. Among them, the fourth parameter range is greater than the third parameter range, and the fourth conduction angle is greater than the third conduction angle. Among them, the values of the fourth conduction angle and the third conduction angle are determined according to empirical values. In this embodiment, the units or parameters of the first capacity threshold C and the second capacity threshold D representing the battery pack capacity size are not limited here. For battery packs with different capacity sizes, the sizes of the first capacity threshold C and the second capacity threshold D are different.

[0069] In some embodiments, similar to the battery pack voltage, the preset power tool 100 parameter thresholds corresponding to the battery pack capacity only include the first capacity threshold C (or the second capacity threshold D). When the battery pack capacity is less than or equal to the first capacity threshold C, the corresponding preset parameter range is 0, and the preset conduction angle is 120°; or when the battery pack capacity is less than or equal to the first capacity threshold C, the corresponding third parameter range, and the preset conduction angle is the third conduction angle. When the battery pack capacity is greater than the first capacity threshold C, the corresponding preset parameter range is the fourth parameter range, and the preset conduction angle is the fourth conduction angle. Specifically, for how the controller 21 controls the value of V1 / V2 and the conduction mode, refer to what is described for the battery pack voltage, which will not be elaborated here.

[0070] In some embodiments, when the parameter of the power tool 100 is the battery pack temperature, after the switch of the power tool 100 is turned on and before the motor 11 starts, the controller 21 can detect the temperature of the battery pack, or the battery pack actively transmits its own temperature information to the controller 21. The controller 21 sets a preset parameter range according to the magnitude of the battery pack temperature. Then, after the motor 11 starts, the controller 21 can control the stator winding to switch to a conduction mode and conduction angle that match the temperature of the battery pack.

[0071] In some embodiments, when the parameter of the power tool 100 is its own temperature, after the switch of the power tool 100 is turned on and before the motor 11 starts, the controller 21 can obtain the temperature of the power tool 100, and then set a preset parameter range according to the temperature of the power tool 100. Then, after the motor 11 starts, the controller 21 can control the stator winding to switch to a conduction mode and conduction angle that match the temperature of the power tool 100.

[0072] When the temperature of the general battery pack or the temperature of the power tool 100 is relatively low, the set preset parameter range is relatively large, that is, the preset parameter range is increased, and the preset conduction angle is also relatively large. When the temperature of the battery pack or the temperature of the power tool 100 is relatively high, the preset parameter range will be reduced, and the preset conduction angle is also relatively small. For example, taking the case where the preset parameter range of the battery pack temperature is the same as that of the power tool 100 temperature, and the preset conduction angles corresponding to the preset parameter ranges of the battery pack temperature and the power tool 100 temperature are the same as an example for specific description. When the temperature of the battery pack or the temperature of the power tool 100 is relatively low, the preset parameter range is (0.2, 0.8), and the preset conduction angle is 160°. When the value of V1 / V2 is within (0.2, 0.8), the controller 21 controls the stator winding to switch the conduction mode to three-three conduction, and controls the conduction angle to be 160°. When the temperature of the battery pack or the temperature of the power tool 100 is relatively high, the preset parameter range is (0.5, 0.7), and the preset conduction angle is 140°. When the value of V1 / V2 is within (0.5, 0.7), the controller 21 controls the stator winding to switch the conduction mode to three-three conduction, and controls the conduction angle to be 140°. When the temperature of the battery pack or the temperature of the power tool 100 is very high, the set preset parameter range is 0, that is, there is no preset parameter range, the value of V1 / V2 will not be within the preset parameter range, and the controller 21 controls the stator winding to switch the conduction mode to two-two conduction, and the conduction angle is 120°. Or, when the temperature of the battery pack or the temperature of the power tool 100 is very high, the set preset parameter range is very small, which is (0.1, 0.2), and the preset conduction angle is 124°. When the value of V1 / V2 is within (0.1, 0.2), the controller 21 controls the stator winding to switch the conduction mode to three-three conduction, and controls the conduction angle to be 124°. In addition, the preset parameter range of the battery pack temperature and the preset parameter range of the power tool 100 temperature may also be different, and the present application does not make any limitations.

[0073] In some embodiments, such as Figure 8As shown, the preset parameter thresholds corresponding to the battery pack temperature for the power tool 100 include a first temperature threshold E and a second temperature threshold F. When the battery pack temperature is less than or equal to the first temperature threshold E, the corresponding preset parameter range is the fifth parameter range, which has a relatively large range, and the corresponding preset conduction angle is the fifth conduction angle. After the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the fifth parameter range, so that the stator winding switching conduction mode is switched to three-phase-three-conduction, and the conduction angle of the stator winding is the fifth conduction angle. When the battery pack temperature is greater than the first temperature threshold E and less than the second temperature threshold F, the corresponding preset parameter range is a variable range, which is inversely proportional to the battery pack temperature, and the preset conduction angle is also inversely proportional to the battery pack temperature. For example, when the battery pack temperature is between the first temperature threshold E and the second temperature threshold F, one temperature corresponds to one preset parameter range or one preset conduction angle, or the temperature between the first temperature threshold E and the second temperature threshold F is further divided into stages, and the temperature within each stage corresponds to one preset parameter range or one preset conduction angle. After the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the corresponding preset parameter range, so that the stator winding switching conduction mode is switched to three-phase-three-conduction, and the conduction angle of the stator winding is the conduction angle corresponding to the temperature inversely. When the battery pack temperature is greater than or equal to the second temperature threshold F, the corresponding preset parameter range is 0. After the motor 11 starts, the value of V1 / V2 will not be within the preset parameter range, and the controller 21 controls the stator winding switching conduction mode to two-phase-two-conduction, and the corresponding conduction angle is 120°. Or as Figure 9 shown, when the battery pack temperature is greater than or equal to the second temperature threshold F, the corresponding preset parameter range is the sixth parameter range, and the corresponding preset conduction angle is the sixth conduction angle. After the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the sixth parameter range, so that the stator winding switching conduction mode is switched to three-phase-three-conduction, and the conduction angle of the stator winding is controlled to be the sixth conduction angle. Among them, the sixth parameter range is smaller than the fifth parameter range, and the sixth conduction angle is smaller than the fifth conduction angle. Among them, the values of the sixth conduction angle and the fifth conduction angle are determined according to empirical values.

[0074] In some embodiments, such as Figure 10As shown, the preset power tool 100 parameter thresholds corresponding to the battery pack temperature only include the first temperature threshold E (or the second temperature threshold F). When the battery pack temperature is less than or equal to the first temperature threshold E, the corresponding preset parameter range is the fifth parameter range, and the corresponding preset conduction angle is the fifth conduction angle. Then, after the motor 11 starts, the controller 21 controls the value of V1 / V2 to be within the fifth parameter range, so that the stator winding switching conduction mode is changed to three-three conduction, and the stator winding conduction angle is the fifth conduction angle. When the battery pack temperature is greater than the first temperature threshold E, the corresponding preset parameter range is 0, and the preset conduction angle is 120°. Then, after the motor 11 starts, the controller 21 controls the stator winding switching conduction mode to two-two conduction, and the conduction angle is 120°. In addition, when the battery pack temperature is greater than the first temperature threshold E, the corresponding preset parameter range can also be the sixth parameter range, and the corresponding preset conduction angle is the sixth conduction angle.

[0075] In some embodiments, the preset power tool 100 parameter thresholds corresponding to the temperature of the power tool 100 include the third temperature threshold G and the fourth temperature threshold H. Among them, the third temperature threshold G can be the same as or different from the first temperature threshold E; the fourth temperature threshold H can be the same as or different from the second temperature threshold F, and the present application does not make any limitations. When the temperature of the power tool 100 is less than or equal to the third temperature threshold G, the corresponding preset parameter range is the seventh parameter range, and the corresponding preset conduction angle is the seventh conduction angle. Specifically, it is similar to the case where the battery pack temperature is less than the first temperature threshold E, and will not be elaborated here. Among them, the seventh parameter range can be the same as or different from the fifth parameter range, and the present application does not make any limitations. When the temperature of the power tool 100 is greater than the third temperature threshold G and less than the fourth temperature threshold H, the corresponding preset parameter range is a variable range, which is inversely proportional to the temperature of the power tool 100, and the preset conduction angle is inversely proportional to the temperature of the power tool 100. Specifically, it is similar to the change when the battery pack temperature is between the first temperature threshold E and the second temperature threshold F, and will not be elaborated here. When the temperature of the power tool 100 is greater than or equal to the fourth temperature threshold H, the corresponding preset parameter range is 0 or the corresponding preset parameter range is the eighth parameter range. When the preset parameter range is the eighth parameter range, the corresponding conduction angle is the eighth conduction angle. Specifically, it is similar to the case where the battery pack temperature is greater than or equal to the second temperature threshold F, and will not be elaborated here.

[0076] In some embodiments, similar to the battery pack temperature, the preset power tool 100 parameter thresholds corresponding to the temperature of the power tool 100 only include the third temperature threshold G (or the fourth temperature threshold H), and will not be elaborated here.

[0077] In the present application, by setting corresponding preset parameter ranges and preset conduction angles for different power tool parameters, and obtaining the power tool parameters and the corresponding preset parameter ranges through a controller before the motor starts, and then controlling the operating parameters of the motor within the preset parameter ranges after the motor starts, so that the stator winding is switched to the conduction mode corresponding to the preset parameter range, and the conduction angle of the power tool is the conduction angle corresponding to the preset parameter range (i.e., the preset conduction angle). When the power tool parameters change, the conduction angle of the motor winding can be controlled to be a reasonable conduction angle, the power tool is not easily protected, and the power tool is not easily shut down, thereby improving the cutting feel of the power tool.

[0078] In some embodiments, the conduction angle of the corresponding stator winding can also be determined comprehensively based on the battery pack voltage, battery pack capacity, battery pack temperature, and the temperature of the power tool 100. After the switch of the power tool 100 is turned on and before the motor 11 starts, the controller 21 can detect the voltage of the battery pack, the capacity of the battery pack, the temperature of the battery pack, and the temperature of the power tool 100. The specific detection methods are as described above in the present application and will not be elaborated here. Exemplarily, the conduction angle corresponding to the battery pack voltage is set as CB1, and the magnitude of CB1 is proportional to the battery pack voltage, that is, the larger the battery pack voltage, the larger CB1. The conduction angle corresponding to the battery pack capacity is set as CB2, and the magnitude of CB2 is proportional to the battery pack capacity, that is, the larger the battery pack capacity, the larger CB2. The conduction angle corresponding to the battery pack temperature is set as CB3, and CB3 is inversely proportional to the battery pack temperature, that is, the higher the battery pack temperature, the smaller CB3. The conduction angle corresponding to the temperature of the power tool 100 is set as CB4, and the magnitude of CB4 is inversely proportional to the temperature of the power tool 100, that is, the higher the temperature of the power tool 100, the smaller CB4. Therefore, after the controller 21 detects the voltage of the battery pack, the capacity of the battery pack, the temperature of the battery pack, and the temperature of the power tool 100, the corresponding conduction angles can be determined.

[0079] In order to comprehensively determine the conduction angle of the corresponding stator winding from the conduction angles corresponding to the battery pack voltage, battery pack capacity, battery pack temperature, and the temperature of the power tool 100, the weight corresponding to CB1 is set as the first weight V1, the weight corresponding to CB2 is set as the second weight V2, the weight corresponding to CB3 is set as the third weight V3, and the weight corresponding to CB4 is set as the fourth weight V4. Among them, the sum of V1, V2, V3, and V4 is 1, and the settings of V1, V2, V3, and V4 are determined according to empirical values. Therefore, the conduction angle of the stator winding can be determined by the formula CB1*V1 + CB2*V2 + CB3*V3 + CB4*V4. Thus, the conduction angle of the corresponding stator winding can be determined jointly based on the battery pack voltage, battery pack capacity, battery pack temperature, and the temperature of the power tool 100.

[0080] The basic principles, main features and advantages of the present application have been shown and described above. Those skilled in the art should understand that the above embodiments do not limit the present application in any form. Any technical solutions obtained by means of equivalent replacement or equivalent transformation fall within the protection scope of the present application.

Claims

1. An electric tool, comprising: Battery pack, providing electrical energy; Motor, including a rotor and a three-phase stator winding; Drive circuit, having a plurality of semiconductor switching elements; Parameter detection module, for detecting the operating parameters of the motor during operation; Controller, electrically connected to at least the battery pack, the drive circuit, and the motor; The controller is configured to: Obtain the power tool parameters; Obtain a corresponding preset parameter range and a preset conduction angle according to the power tool parameters and preset power tool parameter thresholds; Control the operating parameters within the preset parameter range so that the stator winding is switched to the preset conduction angle corresponding to the preset parameter range.

2. The electric tool according to claim 1, characterized in that, The controller is configured to: control the operating parameters within the preset parameter range, so that the stator winding is switched to the corresponding conduction mode of the preset parameter range, and control the stator winding to be switched to the corresponding preset conduction angle based on the conduction mode.

3. The electric tool according to claim 2, characterized in that, During the operation of the motor, the stator winding has a first conduction mode of two-phase winding commutation conduction and a second conduction mode of three-phase winding commutation conduction.

4. The electric tool according to claim 1, characterized in that, The operating parameters include the phase voltage of the floating phase during the commutation of the stator winding and the phase voltage of the conducting phase of the stator winding.

5. The electric tool according to claim 1, characterized in that, The power tool parameters include the battery pack voltage, and the preset power tool parameter thresholds include a first voltage threshold and / or a second voltage threshold.

6. The electric tool according to claim 5, characterized in that, When the battery pack voltage is greater than the first voltage threshold and less than the second voltage threshold, the preset parameter range is proportional to the battery pack voltage; when the battery pack voltage is greater than or equal to the second voltage threshold, the preset parameter range is a first parameter range.

7. The electric tool according to claim 3 or 6, characterized in that, When the preset parameter range is proportional to the battery pack voltage, the conduction mode is the second conduction mode, and the preset conduction angle is proportional to the battery pack voltage; when the preset parameter range is the first parameter range, the conduction mode is the second conduction mode, and the preset conduction angle is a first conduction angle.

8. The electric tool according to claim 6, characterized in that, When the battery pack voltage is less than or equal to the first voltage threshold, the preset parameter range is 0 or the preset parameter range is a second parameter range, and the second parameter range is less than the first parameter range.

9. The electric tool according to claim 3 or 8, characterized in that, When the preset parameter range is 0, the conduction mode is the first conduction mode, and the preset conduction angle is 120°; when the preset parameter range is the second parameter range, the conduction mode is the second conduction mode, and the preset conduction angle is a second conduction angle.

10. The electric tool according to claim 5, characterized in that, When the battery pack voltage is less than or equal to the first voltage threshold or the second voltage threshold, the preset parameter range is 0 or the preset parameter range is a second parameter range; when the battery pack voltage is greater than the first voltage threshold or the second voltage threshold, the preset parameter range is a first parameter range; wherein, the second parameter range is less than the first parameter range.

11. The electric tool according to claim 1, characterized in that, The power tool parameters include the battery pack capacity, and the preset power tool parameter thresholds include a first capacity threshold and / or a second capacity threshold.

12. The electric tool according to claim 11, characterized in that, When the capacity of the battery pack is less than or equal to the first capacity threshold, the preset parameter range is 0 or the preset parameter range is the third parameter range; when the capacity of the battery pack is greater than the first capacity threshold and less than the second capacity threshold, the preset parameter range is proportional to the capacity of the battery pack; when the capacity of the battery pack is greater than or equal to the second capacity threshold, the preset parameter range is the fourth parameter range.

13. The electric tool according to claim 3 or 12, characterized in that, When the preset parameter range is 0, the conduction mode is the first conduction mode, and the preset conduction angle is 120°; when the preset parameter range is the third parameter range, the conduction mode is the second conduction mode, and the preset conduction angle is the third conduction angle.

14. The electric tool according to claim 3 or 12, characterized in that, When the preset parameter range is proportional to the capacity of the battery pack, the conduction mode is the second conduction mode, and the preset conduction angle is proportional to the battery pack voltage; when the preset parameter range is the fourth parameter range, the conduction mode is the second conduction mode, and the preset conduction angle is the fourth conduction angle.

15. The electric tool according to claim 1, characterized in that, The electric tool parameters include the battery pack temperature or the electric tool temperature, and the preset electric tool parameter thresholds include the first temperature threshold and / or the second temperature threshold, the third temperature threshold and / or the fourth temperature threshold.

16. The electric tool according to claim 15, characterized in that, When the battery pack temperature is less than or equal to the first temperature threshold, the preset parameter range is the fifth parameter range, and the preset conduction angle is the fifth conduction angle; When the battery pack temperature is greater than the first temperature threshold and less than the second temperature threshold, the preset parameter range is inversely proportional to the battery pack temperature, and the preset conduction angle is inversely proportional to the battery pack temperature; when the battery pack temperature is greater than or equal to the second temperature threshold, the preset parameter range is the sixth parameter range, and the preset conduction angle is the sixth conduction angle; wherein, the sixth parameter range is less than the fifth parameter range, and the sixth conduction angle is less than the fifth conduction angle.

17. The power tool according to claim 15, characterized in that When the electric tool temperature is less than or equal to the third temperature threshold, the preset parameter range is the seventh parameter range, and the preset conduction angle is the seventh conduction angle; when the electric tool temperature is greater than the third temperature threshold and less than the fourth temperature threshold, the preset parameter range is inversely proportional to the electric tool temperature, and the preset conduction angle is inversely proportional to the electric tool temperature; when the electric tool temperature is greater than or equal to the fourth temperature threshold, the preset parameter range is the eighth parameter range, and the preset conduction angle is the eighth conduction angle; wherein, the eighth parameter range is less than the seventh parameter range, and the eighth conduction angle is less than the seventh conduction angle.

18. The power tool according to claim 3, characterized in that When the stator winding is in the second conduction mode, the conduction angle of the stator winding conduction is greater than 120° and less than 180°.

19. A power tool, comprising: Battery pack, providing electrical energy; Motor, including a rotor and a three-phase stator winding; Drive circuit, having a plurality of semiconductor switching elements; Parameter detection module, for detecting the working parameters during the operation of the motor; Controller, electrically connected to at least the battery pack, the drive circuit and the motor; Wherein, during the operation of the motor, the stator winding has a first conduction mode in which two-phase windings conduct with phase commutation and a second conduction mode in which three-phase windings conduct with phase commutation; The controller is configured to: Obtain the temperature of the battery pack; Control the stator winding to be in the first conduction mode or the second conduction mode according to the temperature of the battery pack.

20. A power tool, comprising: The battery pack provides electrical energy; The motor includes a rotor and a three-phase stator winding; The drive circuit has a plurality of semiconductor switching elements; The parameter detection module is used to detect the operating parameters when the motor is running; The controller is electrically connected to at least the battery pack, the drive circuit and the motor; The controller is configured to: Obtain the power tool parameters; Obtain a corresponding preset parameter range according to the power tool parameters and a preset power tool parameter threshold; Control the operating parameters within the preset parameter range so that the stator winding switches to the conduction mode corresponding to the preset parameter range.

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