CN118282268A

CN118282268A - Electric tool

Info

Publication number: CN118282268A
Application number: CN202311684384.9A
Authority: CN
Inventors: 许彦卿; 陈佚聪; 陆文静
Original assignee: Nanjing Chervon Industry Co Ltd
Current assignee: Nanjing Chervon Industry Co Ltd
Priority date: 2022-12-29
Filing date: 2023-12-08
Publication date: 2024-07-02
Also published as: CN118282269A; CN118282270A; WO2024140217A1

Abstract

The application discloses an electric tool, comprising: a housing forming an accommodation space: the motor is arranged in the accommodating space and comprises a stator and a rotor; a functional element connected to an output shaft of the motor, capable of being driven by the motor; a power supply device for supplying electric power to the electric tool; a driving circuit, a plurality of switch elements for driving the motor; the detection module is used for detecting the working parameters of the motor; a controller electrically coupled to at least the drive circuit and the parameter detection module, wherein the controller comprises: a flux linkage and torque given unit configured to give target values of motor torque and stator flux linkage; a flux linkage and torque estimation unit configured to calculate actual values of motor torque and stator flux linkage according to the operating parameters; a flux linkage and torque comparison unit configured to compare the target value and the actual value; and a voltage vector generation unit configured to output a voltage vector based on the comparison result of the flux linkage and the torque comparison unit, so as to control the on state of the switching element in the driving circuit.

Description

Electric tool

Technical Field

The invention relates to the field of control of electric tools, in particular to an electric tool.

Background

Existing power tools typically employ conventional square wave modulation to drive an internal motor, or use current vector control (FOC) motor rotation, or a combination of both to control motor operation.

However, in the conventional square wave modulation control mode, the brushless motor has only six states in one electrical cycle, or the stator current has six states (six switching states in the three-phase bridge arm). Each current state can be regarded as a vector moment in one direction, six vectors are regularly converted step by step so as to drive the rotor to rotate, the motor rotor can synchronously rotate, and the traditional square wave control implementation mode is simple and convenient, but the motor efficiency is low because the traditional square wave control implementation mode only has six discrete and discontinuous vector moments. The complex coordinate transformation is involved in the FOC control, which is unfavorable for realizing the response rapidity in motor control.

This section provides background information related to the application, which is not necessarily prior art.

Disclosure of Invention

It is an object of the present application to solve or at least mitigate some or all of the above problems. To this end, it is an object of the present application to provide a power tool employing a direct torque control motor.

In order to achieve the above object, the present application adopts the following technical scheme:

A power tool, comprising: a housing for forming an accommodation space: the motor is arranged in the accommodating space and comprises a stator and a rotor; a functional element connected to an output shaft of the motor, drivable by the motor; a power supply device for supplying electric power to the electric tool; the driving circuit is electrically connected with the motor to drive the motor and comprises a plurality of switching elements; a detection module configured to detect an operating parameter of the motor; a controller electrically coupled to at least the drive circuit and the parameter detection module, wherein the controller comprises: a flux linkage and torque given unit configured to give target values of motor torque and stator flux linkage; a flux and torque estimation unit configured to calculate actual values of the motor torque and the stator flux from the operating parameters; a flux linkage and torque comparison unit arranged to compare the target value and the actual value; and a voltage vector generating unit configured to output a voltage vector according to a comparison result of the flux linkage and the torque comparing unit, so as to control a conduction state of a switching element in the driving circuit.

A power tool, comprising: a motor including a stator and a rotor; a power supply device for supplying electric power to the electric tool; an operation component for acquiring user input; the driving circuit is electrically connected with the motor to drive the motor and comprises a plurality of switching elements; a detection module configured to detect an operating parameter of the motor; a controller electrically coupled to at least the drive circuit, the detection module, and the operational component; the controller is configured to: controlling a switching element in the driving circuit to change a conducting state according to the user input and the working parameter so as to drive the motor to operate; wherein the torque response time of the controller is 10 milliseconds or less.

A power tool, comprising: a functional element; a motor for driving the functional element, the motor including a stator and a rotor; a power supply device for supplying electric power to the electric tool; the driving circuit is electrically connected with the motor and the power supply device and comprises a plurality of switching elements; the controller is electrically connected with the driving circuit and used for outputting control signals to the driving circuit so as to control the plurality of switching elements, and the controller is configured to: when the electric tool is in a first operation stage, controlling the driving circuit in a first control mode; when the electric tool is in a second operation stage, controlling the driving circuit in a second control mode; wherein the first control mode is different from the second control mode, and one of the first control mode and the second control mode is direct torque control.

A garden tool, comprising: a functional element; an auxiliary element; a first motor for driving the functional element; a second motor for driving the auxiliary member; a power supply device for supplying electric power to the gardening tool; the first driving circuit is electrically connected with the first motor and the power supply device and used for driving the first motor; the second driving circuit is electrically connected with the second motor and the power supply device and used for driving the second motor; the control assembly is electrically connected with the first driving circuit and the second driving circuit and used for outputting control signals to control the first driving circuit and the second driving circuit, and the control assembly is configured to: controlling the first driving circuit in a first control manner and controlling the second driving circuit in a second control manner, the second control manner being different from the first control manner; at least one of the first control mode and the second control mode is direct torque control.

A power tool, comprising: a brushless motor; a drive circuit configured to supply operating power to the brushless motor, the inverter circuit including a plurality of switching elements; the detection module is configured to acquire working parameters of the brushless motor; and a controller electrically coupled to the drive circuit and the detection module, respectively, the controller employing closed loop control, the controller configured to: determining a first load point based at least on user input, determining a first flux linkage and a torque-given manner corresponding to the first load point; and based on the first flux linkage and the difference value between the target value given by the torque given mode and the working parameter, outputting an adaptive voltage vector to control the on-off of the switching elements; determining a change from the first load point to a second load point; and determining a second flux linkage and a torque given mode corresponding to the second load point, and outputting an adaptive voltage vector to control the on-off of the switching elements based on a target value given by the second flux linkage and the torque given mode and a difference value of the working parameters.

A power tool, comprising: the brushless motor comprises a rotor and a stator; a power supply device configured to supply power to the brushless motor; a drive circuit configured to provide operating power to the brushless motor; a detection module configured to detect an operating parameter of the brushless motor; and a controller electrically coupled to the detection module and the inverter circuit, the controller comprising: a flux linkage giving unit for outputting a reference value of flux linkage of the stator; a flux linkage estimation unit configured to estimate an actual value of flux linkage of the stator according to the operation parameter; the controller is configured to control the driving circuit to drive the brushless motor in a closed-loop control manner at least according to a comparison result of a flux linkage reference value and an actual value of the stator; wherein the flux linkage giving unit decreases the reference value of the flux linkage of the stator when the target rotational speed of the brushless motor is equal to or greater than a first rotational speed threshold.

A power tool, comprising: the brushless motor comprises a rotor and a stator; a drive circuit configured to provide operating power to the brushless motor; the battery pack is at least used for supplying power to the driving circuit; a detection module configured to detect an operating parameter of the brushless motor; and a controller electrically connected to the battery pack and the driving circuit, respectively, the controller comprising: a flux linkage giving unit for outputting a reference value of flux linkage of the stator; a flux linkage estimation unit configured to estimate an actual value of flux linkage of the stator according to the operation parameter; the controller is configured to control the driving circuit to drive the brushless motor in a closed-loop control manner at least according to a comparison result of a flux linkage reference value and an actual value of the stator; wherein the flux linkage giving unit decreases a reference value of flux linkage of the stator when an output voltage of the battery pack is equal to or less than a first voltage threshold.

A power tool, comprising: an electric machine comprising a rotor and a stator; a power supply device configured to supply electric power to the motor; a driving circuit including a plurality of switching elements; the detection module is used for detecting the working parameters of the motor; a controller electrically connected to the power supply device and the inverter circuit; the controller includes: a torque setting unit for outputting a reference value of torque of the motor; a torque estimation unit configured to estimate an actual value of torque of the motor based on an operation parameter of the motor; the controller generates a voltage vector in a hysteresis control mode at least according to a comparison result of a torque reference value and an actual value of the motor to control the driving circuit to drive the motor; wherein, in response to the braking signal, the reference value of the torque output by the torque given unit is zero or less, thereby controlling the driving circuit to brake the motor.

A power tool, comprising: an electric machine comprising a rotor and a stator; a power supply device configured to supply electric power to the motor; a driving circuit including a plurality of switching elements; the detection module is used for detecting the working parameters of the motor; a controller electrically coupled to the power supply device and the drive circuit; wherein the controller is configured to: determining a target torque and a target stator flux linkage of the electric machine; estimating the actual torque and the actual stator flux of the motor according to the working parameters; calculating a torque difference value according to the target torque and the actual torque of the motor; calculating a flux linkage difference value according to a target stator flux linkage of the motor and the actual stator flux linkage; outputting a control signal based at least on the flux linkage difference and the torque difference; the controller increases the target stator flux in response to a deceleration signal output by the operating assembly.

A power tool, comprising: an electric machine comprising a rotor and a stator; a power supply device configured to supply electric power to the motor; a driving circuit including a plurality of switching elements including an upper side switching element and a lower side switching element; the detection module is used for detecting the working parameters of the motor; a controller electrically connected to the power supply device and the drive circuit, the controller configured to: determining a target torque and a target stator flux linkage of the electric machine; acquiring actual torque and actual stator flux linkage of the motor according to the working parameters; comparing the target torque with the actual torque, comparing the target stator flux linkage with the actual stator flux linkage, and generating control signals to control the on-off of the plurality of switching elements according to the comparison result; wherein, in response to a braking signal, the controller controls the motor to brake in at least two ways of increasing the target stator flux, setting the target torque to a negative value, and opening all switching elements in all the driving circuits.

A power tool, comprising: a motor including a stator and a rotor; a power supply device for supplying electric power to the motor; the driving circuit is electrically connected with the motor to drive the motor and comprises a plurality of switching elements; the detection module is configured to acquire the working parameters of the motor; and a controller for controlling the drive circuit, the controller configured to: setting a reference value of flux linkage of the stator and a reference value of torque of the motor; estimating the actual values of the flux linkage of the stator and the torque of the motor according to the working parameters of the motor; predicting a predicted value of the flux linkage of the stator and the torque of the motor at a next moment according to at least the actual values of the flux linkage of the stator and the torque of the motor; comparing the predicted value of the flux linkage of the stator with the reference value of the flux linkage of the stator to obtain a flux linkage difference value; comparing the predicted value of the torque of the motor with the reference value of the torque of the motor to obtain a torque difference value; and generating a control signal at least according to the flux linkage difference value and the torque difference value to control the conduction states of the switching elements.

A power tool, comprising: a motor including a stator and a rotor; a power supply device for supplying electric power to the motor; the driving circuit is electrically connected with the motor to drive the motor and comprises a plurality of switching elements; a controller for controlling the driving circuit, the controller comprising: a torque difference calculation unit configured to calculate a torque difference from a target torque and an actual torque of the motor; a flux linkage difference value calculation unit configured to calculate a flux linkage difference value from a target stator flux linkage and an actual stator flux linkage of the motor; a voltage vector generation unit configured to generate control signals for controlling the plurality of switching elements based at least on the torque difference value, the flux linkage difference value, and the angular position of the rotor; the voltage vector generation unit adopts at least one control mode of sliding mode control, fuzzy logic control and artificial neural network control to adaptively adjust the target torque and the target stator flux linkage.

An electric drill, comprising: a functional element; the motor is used for driving the functional element to rotate and comprises a stator and a rotor; the power supply module is used for supplying power to the motor; the driving circuit is electrically connected with the motor and the power supply module and comprises a plurality of switching elements; a detection module configured to detect an operating parameter of the motor; a controller electrically coupled to the drive circuit and the detection module, the control module configured to: setting a target torque and a target stator flux linkage of the motor; estimating the actual torque and the actual stator flux of the motor according to the working parameters; calculating a torque difference value according to the target torque and the actual torque of the motor; calculating a flux linkage difference value according to a target stator flux linkage of the motor and the actual stator flux linkage; generating a control signal to control the drive circuit based at least on the flux linkage difference and the torque difference; and when the actual torque of the motor is greater than or equal to the target torque, the control module controls the motor to stop rotating.

Drawings

Fig. 1 is an external view of an electric drill;

FIG. 2 is a block diagram of circuitry of a power tool of one embodiment;

FIG. 3 is a circuit schematic of the drive circuitry in the circuitry shown in FIG. 2;

FIG. 4 is a block diagram of circuitry of a power tool of one embodiment;

FIG. 5 is a schematic diagram of spatial voltage vectors in one embodiment;

FIG. 6 is a diagram of a switch state selection table in one embodiment;

FIG. 7 is a schematic diagram of the stator flux linkage of the motor and the motor speed in one embodiment as a function of control;

FIG. 8 is a block diagram of circuitry of a power tool of one embodiment;

FIG. 9 is a block diagram of circuitry of a power tool of one embodiment;

FIG. 10 is a block diagram of circuitry of a power tool of one embodiment;

fig. 11 is a circuit system block diagram of a power tool of one embodiment.

Detailed Description

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 following drawings.

In the present disclosure, the terms "comprises," "comprising," "has," "having," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one … …" does not exclude the presence of other like elements in a process, method, article, or apparatus that comprises the element.

In the present application, the term "and/or" is an association relationship describing an association object, meaning that three relationships may exist. For example, a and/or B may represent: a exists alone, A and B exist together, and B exists alone. In the present application, the character "/" generally indicates that the front and rear related objects are in an "and/or" relationship.

In the present application, the terms "connected," "coupled," and "mounted" may be directly connected, coupled, or mounted, or indirectly connected, coupled, or mounted. By way of example, two parts or components are connected together without intermediate members, and by indirect connection is meant that the two parts or components are respectively connected to at least one intermediate member, through which the two parts or components are connected. Further, "connected" and "coupled" are not restricted to physical or mechanical connections or couplings, and may include electrical connections or couplings.

In the present application, one of ordinary skill in the art will understand that relative terms (e.g., "about," "approximately," "substantially," etc.) used in connection with quantities or conditions are intended to encompass the values and have the meanings indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a particular value, the tolerance associated with a particular value resulting from manufacture, assembly, use, 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 the addition or subtraction of a percentage (e.g., 1%,5%,10% or more) of the indicated value. Numerical values, not employing relative terms, should also be construed as having specific values of tolerance. Further, "substantially" when referring to relative angular positional relationships (e.g., substantially parallel, substantially perpendicular) may refer to adding or subtracting a degree (e.g., 1 degree, 5 degrees, 10 degrees, or more) from the indicated angle.

In the present application, those of ordinary skill in the art will appreciate that the functions performed by a component may be performed by a component, a plurality of components, a part, or a plurality of parts. Also, the functions performed by the elements may be performed by one element, by an assembly, or by a combination of elements.

In the present application, the terms "upper", "lower", "left", "right", "front", "rear", and the like are described in terms of orientation and positional relationship shown in the drawings, and should not be construed as limiting the embodiments of the present application. In the context of this document, it will also be understood that when an element is referred to as being "on" or "under" another element, it can be directly on the other element or be indirectly on the other element through intervening elements. It should also be understood that the terms upper, lower, left, right, front, back, etc. are not only intended to represent positive orientations, but also to be construed as lateral orientations. For example, the lower side may include a right lower side, a left lower side, a right lower side, a front lower side, a rear lower side, and the like.

In the present application, the terms "controller", "processor", "central processing unit", "CPU", "MCU" are interchangeable. Where a unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a particular function, such function may be performed by a single unit or by a plurality of units unless otherwise indicated.

In the present application, the terms "means," "module," or "unit" may be implemented in hardware or software for the purpose of realizing a specific function.

In the present application, the terms "computing," "determining," "controlling," "determining," "identifying," and the like refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

The electric tool in the present application may be a hand-held power tool, such as a drill, a pruner, a sander, or the like. Or the power tool may also be a table-type tool, such as a table saw, miter saw, or the like. Or the power tool may be a hand propelled power tool, such as a hand propelled mower, a hand propelled snowplow. Or the power tool may also be a riding power tool, such as a riding lawn mower, a riding vehicle, an all-terrain vehicle, or the like. Or the power tool may also be a robotic tool, such as a mowing robot, snowplow robot, or the like. In some embodiments, the power tool may be an electric drill, an electric light, an electric vehicle, or the like. In some embodiments, the power tool may also be a garden tool, such as a pruner, blower, mower, chain saw, or the like. Or the power tool may be a decorative tool such as a screwdriver, nail gun, circular saw, sander, or the like. In some embodiments, the power tool may also be a vegetation care tool, such as a lawnmower, a mower, a pruner, a chain saw, or the like. Or the power tool may also be a cleaning tool such as a blower, snowplow, washer, or the like. Or the power tool may also be a drill-type tool such as a drill, screwdriver, wrench, electric hammer, etc. Or the power tool may also be a saw-type tool such as a reciprocating saw, a jig saw, a circular saw, or the like. Or the power tool may also be a table-type tool such as a table saw, miter saw, metal cutting machine, electric wood-milling, or the like. Or the power tool may also be a sanding type tool such as an angle grinder, sander, etc. Or the power tool may be another tool such as a fan or the like. Of course, the load may also comprise other types of consumer. It is within the scope of the present application to provide such power tools that employ the following disclosed embodiments.

Referring to fig. 1, a power tool 10 will be described by taking a power drill as an example. The power tool 10 mainly includes: a housing 11, a functional element 12, a grip portion 13, an operating assembly 14, a motor 15, and a power supply device 16. Of course, the drill also includes a drive mechanism, drill bit, circuit board, etc. (not exposed in the view of fig. 1).

The housing 11 is formed with a grip portion 13, and the grip portion 13 is gripped by a user, and of course, the grip portion 13 may be a separate component. The housing 11 constitutes a main body portion of the power tool 10 for accommodating a motor 15, a transmission mechanism, and other electronic components such as a circuit board. The front end of the housing 11 is used for mounting the functional element 12.

The functional element 12 is used to perform the function of the power tool 10, which is driven by a motor 15. The functional elements are different for different power tools. By way of example, for a sanding tool the functional element 12 may be a sanding element, such as a sanding disc or sandpaper, etc., for a cutting tool the functional element 12 may be a cutting element, such as a chain, cutterhead or blade or straw, etc., for a cleaning tool the functional element 12 may be a cleaning or blowing element, such as a cleaning brush head, a blowing drum, etc., and for a fastening tool the functional element 12 may be a fastening element, such as a sleeve or a screwdriver head, etc. In this embodiment, the functional element 12 is a drilling member, such as a drill bit (not shown), for performing a drilling function for the drill. The drill bit is operatively connected to the motor 15, and in particular, the drill bit is electrically connected to the motor 15 via an output shaft and a transmission mechanism.

The operating assembly 14 is operable by a user to control the operation of the power tool 10. The general operating assembly 14 may be operated directly manually by a user or indirectly. In one embodiment, the operating assembly 14 may be a speed governor mechanism. The user may directly manually press or rotate or slide the portion of the governor mechanism 14 for operation by the user to control the operation of the power tool 10. The speed regulating mechanism 14 is at least used for setting a target rotation speed of the motor 15, that is, the speed regulating mechanism 14 is used for realizing speed regulation of the motor 15, and the speed regulating mechanism 14 can be, but is not limited to, a trigger, a knob, a switch, a slide rheostat and the like. In the present embodiment, the speed regulating mechanism 14 is configured as a trigger structure. The foregoing is illustrative only and is not to be construed as limiting the invention. In one embodiment, the operating assembly 14 may also include an internet of things module that may wirelessly communicate with other external devices so that a user may indirectly control the operation of the power tool 10 via the other external devices. For example, the internet of things module may communicate with smart terminal devices such as a smart phone by using a wireless communication manner such as bluetooth or WiFi, and thus the user may control the electric tool 10 or remotely control the electric tool 10 based on a terminal application installed in the smart phone.

In this embodiment, the motor 15 may be a brushless motor. In one embodiment, the motor 15 may be an inner rotor motor. In one embodiment, the motor 15 may be an external rotor motor. In one embodiment, the motor 15 may be a brushless motor.

The power supply device 16 is used to provide power to the power tool 10. In this embodiment, the power tool 10 is powered by a battery pack 16. Alternatively, the power tool 10 further includes a battery pack coupling 17 for connecting the battery pack 16 to the power drill. In other embodiments, the power supply 16 may also be an ac power source, and in other embodiments, the power tool 10 is powered by an ac power source, where the ac power source may be 120V or 220V ac mains, and the power supply 16 includes a power conversion unit connected to the ac power for converting the ac power into electric energy for use by the power tool 10.

In another embodiment of the present invention, a hand-held power tool includes a motor having a stator and a rotor; a motor drive shaft or output shaft driven by the motor rotor; a tool attachment shaft for supporting a tool attachment; and the transmission device is used for connecting the motor output shaft to the tool accessory shaft and transmitting the torque output by the motor to the functional element of the tool. The motor output shaft may be coaxial, substantially parallel, substantially perpendicular or inclined to the axis of the functional element, without limitation.

In yet another embodiment of the present invention, a garden tool, such as a vehicular mower, includes a body, at least one drive wheel or set of drive wheels supported by the body; a drive device, such as a motor, for providing torque to the at least one drive wheel or set of drive wheels; and circuitry to control motor drive operation, as described below.

Referring to fig. 2, the circuit system 20 of the embodiment of the electric power tool 10 includes a power supply 21, a controller 22, a driving circuit 23, a detection module 24, and a motor 25. The controller 22 may include a flux and torque given unit 221, a flux and torque estimation unit 222, a flux and torque comparison unit 223, and a voltage vector generation unit 224, among others. In some embodiments, the flux linkage and torque given unit may also be referred to as a torque and flux linkage given unit or may be divided into two sub-units, namely a flux linkage given unit, a torque given unit, and in addition, a torque and flux linkage estimation unit and a torque and flux linkage comparison unit may also be described in the above manner. Different descriptions may be employed in different embodiments of the present application.

For the sake of clarity in distinguishing between the different embodiments, the present application may have different numbers for the same components in the different embodiments, but it is understood that the same components, for example, the power supply device 16 in fig. 1 and the power supply device 21 in fig. 2, each represent the power supply device of the electric tool 10.

The power supply device 21 is used to power the power tool 10, and in some embodiments, the power supply device 21 outputs direct current, more specifically, the power supply device 21 includes a battery pack. In other embodiments, the power supply device 21 outputs ac power, which may be 120V or 220V ac mains, and the ac power is converted into electric energy for use by the electric tool by rectifying, filtering, voltage dividing, voltage reducing, etc. the ac signal output by the ac power through the hardware circuit. In the present embodiment, the electric power tool 10 is powered using a battery pack, and the power supply device 21 includes the battery pack.

The detection module 24 is capable of detecting an operating parameter of the motor 25, such as at least one of a phase current, a phase voltage, a rotational speed, a torque, a number of turns, a rotor position, a stator resistance, etc. of the motor 25.

The drive circuit 23 may also be referred to as an inverter. The driving circuit 23 is electrically connected to the controller 22 and the motor 25, and is capable of driving the motor 25 to operate according to a control signal of the controller 22. For a three-phase motor, the drive circuit 23 is in particular electrically connected to the three-phase windings of the motor 25 for transmitting current from the power supply device 21 to the stator windings for driving the motor 25 in rotation. In one embodiment, the driving circuit 23 includes a plurality of switching elements Q1, Q2, Q3, Q4, Q5, Q6 as shown in fig. 3. Q1, Q3, and Q5 are high-side switching elements, and Q2, Q4, and Q6 are low-side switching elements. Any one phase stator winding of the motor 25 is connected to a high-side switching element and a low-side switching element. The gate terminal of each switching element in the driving circuit 23 is electrically connected to the controller 22, and is configured to receive a control signal from the controller 22. The drain or source of each switching element is connected to the stator winding of the motor 25. The switching elements Q1 to Q6 receive control signals from the controller 22 to change the respective conductive states, thereby changing the current applied to the stator windings of the motor 25 by the power supply device 21. In one embodiment, the drive circuit 23 may be a three-phase bridge driver circuit including six controllable semiconductor power devices (e.g., FETs, BJTs, IGBTs, etc.). It will be appreciated that the switching element may be any other type of solid state switch, such as an Insulated Gate Bipolar Transistor (IGBT), a Bipolar Junction Transistor (BJT), etc.

For driving the motor 25 to rotate, the driving circuit 23 has a plurality of driving states, and the rotation speed or the steering of the motor 25 may be different in different driving states. In one embodiment, the driving circuit 23 generally has at least six driving states, and each switching of the driving states corresponds to one commutation of the motor. In one embodiment, the controller 22 may output a pulse width modulated signal to control the drive circuit 22 to switch the drive state, thereby changing the operating state of the motor 25.

In the present embodiment, the controller 22 can output a voltage vector to the driving circuit 23 to directly control the on state of the switching element in the driving circuit 23. The voltage vector may be a space vector pulse width modulated (Space Vector Pulse Width Modulation, SVPWM) waveform of the voltage generated by the controller 22. In one embodiment, the controller 22 may calculate and control the torque of the motor 25 in a stator coordinate system. Without the need to re-split the motor current into torque and flux linkage components, rotational transformation and current control are eliminated, and thus the torque control response time of the controller 22 is shorter and the complexity of motor control is reduced. In this embodiment, the manner in which the controller 22 directly controls the torque of the motor 25 may be referred to as direct torque control (Direct Torque Control, DTC). In the present embodiment, the response time of the torque in the direct torque control process is 10ms or less, and may be 10ms,9ms,8ms,7ms,6ms,5ms,4ms,3ms,2ms,1ms, or the like, for example.

Referring to fig. 2 and 4, the flux linkage and torque given unit 221 in the controller 22 may give a target value of motor torqueTarget value of stator flux linkageThe target value may be referred to as a reference value, which is a value of output torque and stator flux linkage that a user desires to achieve by the motor 25 in the power tool, and may be understood as a user input generated by the user operating the operating assembly 14. Illustratively, when the operating assembly 14 is a trigger, the user input is a trigger stroke that corresponds to a target value of torque and stator flux that the motor 25 should output, or when the operating assembly 14 is a speed knob, the user inputs a gear of an un-speed knob, the motor 25 having different torques and stator flux at different gears. In this embodiment, the target value of the stator flux is the magnitude of the specified sub flux. In the present embodiment, the target value of the motor torque may be obtained by PI operation of the target speed, that is, after the user inputs the target speed, the flux linkage and torque given unit 221 determines the target value of the motor torque by PI operation. In one embodiment, the user may also directly give the target value of motor torque through the operating assembly 14, for example, in a saddle-type electric device, the user directly sets the target torque by manipulating the pedal.

The flux linkage and torque estimation unit 222 may estimate an actual value T _e of the torque of the motor 25 and an actual value of the stator flux linkage based on the operation parameters of the motor 25 detected by the detection module 24Wherein the actual value of the stator flux linkage is also the actual amplitude of the given stator flux linkage. In the present embodiment, the flux linkage and torque estimation unit 222 may estimate the actual value of the stator flux linkage based on the stator resistance R _s of the motor 25. In a specific implementation, the stator flux linkage vector may be obtained by integrating the back emf:

Wherein R _s is the internal resistance of the stator, For the terminal voltage of the stator,For stator flux linkage, I _s is the stator current of the motor.

From the above formula, the counter electromotive force of the stator winding can be calculated by the formulaAnd (5) calculating. At high speed operation of the motor, the counter potential of the stator winding is large, so evenThe large deviation does not cause obvious influence on the back electromotive force, so that the influence on the stator flux linkage is small. On the contrary, when the motor runs at a low speed, the counter electromotive force is smaller, and if the deviation of the internal resistance R _s is larger, the counter electromotive force is obviously influenced, so that the accuracy of stator flux linkage calculation is influenced. That is, the stator flux linkage is critical to calculate at low speeds. To obtain good performance at rest and low speeds, a low pass filter with a cut-off frequency of ω _f can be introduced to eliminate the integral drift caused by the dc offset and measurement. The stator flux linkage can thus be expressed as:

Wherein ω _s is the frequency at which the stator flux rotates. As can be seen from the formula (3), at low speeds, the stator internal resistance is dominant, and in fact if the estimated stator internal resistance is greater than the actual resistance, the time constant of the following differential equation (4) obtained from the formula (1) is negative, which may lead to motor runaway.

Wherein sigma is an influence factor, L _s is a stator inductance, L _r is a rotor inductance, L _m is a magnetizing inductance,As for the rotor flux linkage, the accuracy of the stator internal resistance detection directly influences the determination of the actual value of the stator flux linkage of the motor at low speed according to the formula. In one embodiment, the detection module 24 may be a resistive observer or an inductive observer, with which the stator resistance of the motor 25 can be more accurately observed. In one embodiment, the power tool 10 may also be provided with a resistive cooling device for dissipating heat from the stator of the motor.

In one embodiment, the fuzzy controller can be used for estimating the internal resistance of the stator in real time through fuzzy control, and the working parameters of the motor can be updated in real time according to the real-time internal resistance value. Specifically, the phase and amplitude errors between the estimated stator flux and the filtered stator flux can be used as input variables of the fuzzy controller. The output variable of the fuzzy controller is the change rate generated by fuzzy reasoning and defuzzification, and the final change amount is zero after the continuous iteration of the change amount is stabilized, so that the accuracy of the internal resistance estimation can be ensured.

The flux linkage and torque comparison unit 223 may compare the above-described target value and the actual value to determine a difference between the actual stator flux linkage and the target stator flux linkage, and a difference between the actual torque and the target torque. In this embodiment, the flux linkage and torque comparison unit 223 may include at least one hysteresis comparator, and when the error between the actual value and the target value is within the tolerance range of the hysteresis comparator, the output of the comparator remains unchanged, and once this range is exceeded, the hysteresis comparator gives a corresponding value. In the specific implementation, the hysteresis comparator can perform hysteresis processing on the torque difference to obtain a torque control signal; and comparing the flux linkage estimated value with a given flux linkage, and obtaining a flux linkage control signal through a hysteresis comparator.

The voltage vector generation unit 224 may output a voltage vector, i.e., output a SVPWM signal to control the driving circuit 23 to change the on state, according to the comparison result output by the flux linkage and torque comparison unit 223. In one motor modulation period, namely 360-degree commutation period, the rotor commutates once every 60-degree motor, and the interval from one commutation of the motor to the next commutation is defined as a commutation interval. Each commutation interval corresponds to one sector shown in fig. 5. Each sector corresponds to a switching state and the space voltage vector can be understood as a voltage signal that causes the drive circuit 23 to have a different switching state. In this embodiment, the voltage vector generating unit 224 may actually include a DTC switch table, i.e. a switch state selection table, as shown in fig. 6, in whichRepresenting the difference between the actual value and the target value of the stator flux linkage, deltaT represents the difference between the actual value and the target value of the torque of the motor, and u0-u7 represent eight switching states, where u0 and u7 are each zero vectors, and the corresponding switching states are (0, 0) or (1, 1). In this embodiment, the voltage vector generation unit 224 may generate the SVPWM waveform through the frequency converter to control the operation of the motor 25 after determining the voltage vector.

In the present embodiment, it is considered that the controller 22 can generate a voltage vector to control the motor operation in a hysteresis control manner based on the comparison result of the actual value and the target value of the torque and the comparison result of the actual value and the target value of the stator flux linkage.

The power tool may have a higher rotational speed when operating in a light load phase, and may require a greater output torque when operating in a heavy load phase. That is, the controller 22 may control the motor to change the output torque or change the rotational speed according to the load condition of the power tool. In the vector control technology of a permanent magnet synchronous motor or a direct current motor, a direct-axis component can form two areas of magnetism increasing (Id > 0) and magnetism weakening (Id < 0) of a permanent magnet in motion, and a direct-current component in a motor stator current in a magnetism weakening area can form a demagnetization effect, so that the low-magnetism high-speed operation of the motor can be realized.

The direct torque control of the motor can also adopt a weak magnetic mode to increase the rotating speed of the motor. However, unlike the field weakening in the vector control method, the field weakening effect substantially the same as that in the proper amount of control can be achieved by reducing the target value of the stator flux linkage in the direct torque control.

In one implementation, controller 22 may decrease the reference or target value of the stator flux when the target speed of the motor is greater than or equal to the first speed threshold. The first rotation speed threshold may be a higher rotation speed value, may be the highest rotation speed that the electric tool can reach when not using weak magnetic acceleration, and the first rotation speed threshold corresponding to different types of electric tools may be different, for example, the first rotation speed threshold of the electric drill may be 27000RPM. In one embodiment, the rotational speed of the drill may reach 35000RPM after direct torque control and flux weakening acceleration. In other words, when the target rotation speed to be achieved by the motor 25 is relatively large, the motor rotation speed may be increased in a field weakening manner so that the motor can achieve the target rotation speed, and when the target rotation speed is relatively small, the field weakening acceleration may not be employed. Next, the effect of using weak magnetic flux to accelerate in the DTC control mode will be described in conjunction with the planned change relationship between the stator flux linkage and the motor speed, referring to fig. 7, assuming that the motor is stably operated at 1200rpm before time t1, and that the user operates the operating unit 14 to set a target speed of 2200rpm at time t1, the controller 22 starts to control the motor 25 to accelerate from time t1, and assuming that the motor speed reaches the first speed threshold value corresponding to the electric tool at time t2, the controller 22 starts to reduce the target value of the stator flux linkage, and controls the motor 25 to continue accelerating in a weak magnetic flux manner, and reaches the target speed of 2200rpm at time t 3.

When the operating assembly 14 of the power tool 10 is a trigger, the greater the target rotational speed that the motor is required to achieve, generally as the trigger travel increases. Therefore, the target rotational speed that the motor needs to reach in the latter half of the operation of the trigger will be greater than or equal to the first rotational speed threshold, and the controller 22 needs to decrease the target value of the stator flux linkage to enhance the field weakening effect of the stator winding and increase the motor rotational speed. In some particular tools, the smaller the target rotational speed that the motor needs to achieve, the weaker magnetic acceleration is required in the first half of the trigger travel, perhaps as the trigger travel increases.

If the power supply device 21 is a battery pack or other energy storage device, the voltage of the battery pack will be continuously reduced as the battery pack is continuously discharged, and the input power of the electric tool will be reduced after the voltage of the battery pack is lower than the rated voltage or lower than other preset values, and the motor rotation speed will be reduced under the condition that the load is unchanged. In this case, to increase the motor speed, the controller 22 may decrease the target value of the stator flux linkage to enhance the field weakening effect of the stator winding and increase the motor speed. In one embodiment, the flux and torque given unit 221 may decrease the target value of the stator flux to increase the rotation speed of the motor when the output voltage of the battery pack is equal to or less than the first voltage threshold. The first voltage threshold may be a rated voltage of the battery pack or an undervoltage threshold of the battery pack.

In one embodiment, the controller 22 may rationally adjust the target value of the motor's stator flux linkage to control the torque or rotational speed actually output by the motor 25, depending on the load condition of the tool. For example, in light load conditions, the motor may operate at a high rotational speed, while in heavy load conditions, the motor may require a low rotational speed and high torque. That is, under light load conditions, the flux linkage and torque giving unit 221 in the controller 22 may decrease the target value of the stator flux linkage to increase the rotational speed of the motor. Conversely, if the target value of the stator flux linkage is increased, the weak magnetic effect is reduced, and the motor rotating speed can be reduced, or the motor torque can be increased.

In one embodiment, the controller 22 may also boost the torque of the motor by reducing the field weakening effect. In one embodiment, under heavy load conditions, the flux linkage and torque given unit 221 may increase the target value of the stator flux linkage to increase the torque of the motor. The electric drill can increase the motor rotation speed in a weak magnetic mode when drilling on the cork, and needs larger output torque when drilling on hard materials such as steel plates, and can reduce the weak magnetic effect and increase the motor torque.

In one embodiment, a condition identification module may be provided within the power tool 10 that is capable of identifying the current operating condition of the power tool. The condition recognition module may, for example, recognize a condition by recognizing the output power of the motor, or recognize a condition by user input, or recognize a condition by the actual rotational speed of the motor, or by

The more the motor speed is increased, the more the working noise of the electric tool is increased, and the controller 22 can balance the noise decibel with the motor speed to set a rotating speed, so that the noise decibel is in the range acceptable by human ears during the working process of the electric tool at the set rotating speed. The flux linkage and torque setting unit 221 may increase the target value of the stator flux linkage and decrease the motor speed such that the final motor speed substantially coincides with the set speed.

In one embodiment, in the process that the controller 22 reduces the target value of the stator flux linkage to control the weak magnetic speed of the motor, the permanent magnet enters the weak magnetic area, and the nonlinear aggravation of the permanent magnet and the silicon steel sheet of the motor can cause the control precision of the motor to be reduced, so that the harmonic wave becomes larger. In this embodiment, the controller 22 may reduce the field weakening effect by increasing the target value of the stator flux linkage, so that the motor operates in the linear region as much as possible, thereby reducing harmonic interference and ensuring the control accuracy of the motor. In one embodiment, the controller 22 may detect the degree of nonlinearity of the flux linkage of the permanent magnet and the silicon steel sheet of the motor and increase the stator flux linkage target value accordingly, avoiding the motor braking with a greater increase in the stator flux linkage target value while avoiding the stator flux linkage target value increasing less than the effect of eliminating harmonics.

In one embodiment, the controller 22 may also adjust the target value of the stator flux linkage after integrating the current conditions of the power tool 10, such as noise decibels, and harmonic magnitudes, so that the power tool can satisfy the balance of the relationships of noise, operation comfort, and the like under any working condition.

In one embodiment, the power tool may need to be rotated at a higher speed during some conditions and output power during some conditions. In order to adapt to different demands of the tool, the controller can switch the control modes, and particularly can switch the control modes according to the change of the load point of the motor. The load point may be determined according to a target torque or a target rotation speed of the motor input by a user, for example, several different application conditions such as high rotation speed and low torque, high rotation speed and high torque, low rotation speed and low torque, and low torque and high torque. In the embodiment of the present application, the high and low are relative concepts rather than absolute values, and the different rotational speeds or torques of different electric tools are divided differently, which is not absolutely defined herein.

The circuitry 30 shown with reference to fig. 8 includes: a power supply 31, a controller 32, a driving circuit 33, and a motor 34. The controller 32 includes a flux linkage estimation unit 321, a torque estimation unit 322, a torque setting unit 323, a flux linkage setting unit 324, a rotation speed regulator 325, a maximum torque flux linkage ratio controller 326, a torque comparison unit 327, a flux linkage comparison unit 328, and a switch table 329.

In the present embodiment, the flux linkage estimation unit 321 and the torque estimation unit 322 are consistent with the flux linkage and torque estimation unit 222 in the above embodiments, and are used to determine the actual value T _e of the motor torque and the actual value of the stator flux linkage according to the operation parameters of the motorAnd the two estimation units may be estimated in a manner substantially identical to that of the flux linkage and torque estimation unit 222, which will not be described in detail herein. In alternative embodiments, the flux linkage estimation unit 321 and the torque estimation unit 322 may also be combined into one estimation unit.

The torque giving unit 323 can determine a target value of the motor torque based on the user inputThe flux linkage giving unit 324 may also determine a target value of the stator flux linkage based on user inputFor example, the user input may be a user operating the operating component to achieve a target rotational speed of the corresponding motor in either state.

The speed regulator 325 can determine a target value of the motor torque based on the actual speed n of the motor 34 and a target value n ^*, which is a given value of the motor speed.

The maximum torque flux ratio controller 326 may set a value of a minimum stator flux that enables the motor to be operated rotationally at a target torque, based on the target torque of the motor. It will be appreciated that in direct torque control, the stator flux linkage may not be the only value determined if a certain torque output is to be achieved, i.e. the stator flux linkage may be of a value within a certain range that would allow the motor to have the same output torque. And the maximum torque flux ratio controller 326 can control the motor to output a certain torque with the minimum stator flux, so as to ensure that the motor has the maximum power.

Unlike the above embodiment, the circuit system 30 in this embodiment further includes a first switch S1 and a second switch S2. The controller 32 may determine the load point based on user input and may in turn control the two switches S1 and S2 to change the switch state based on the load point or a change in the load point. For example, the controller 32 may control the two switches S1 and S2 to be in the first switching state, i.e., the switch S1 is connected to the torque giving unit 323 and the switch S2 is connected to the flux linkage giving unit 324, when it is determined that the power tool is at the first load point according to the user input. In this switching state the controller 32 is able to set the target value of the torque by the torque setting unit 323 in a first torque and flux linkage setting mannerAnd the target value of the stator flux is given by the flux linkage giving unit 324And the controller 32 can increase the field weakening effect by decreasing the stator flux target value and increase the motor speed under the first torque and flux set mode. That is, the first torque and flux linkage given manner coincides with the given manner of torque and flux linkage in the above-described embodiment.

When the controller 32 determines a change in the power tool from the first load point to the second load point, the two switches S1 and S2 may be controlled to switch to the second switch state, i.e., S1 is coupled to the speed regulator 325 and S2 is coupled to the maximum torque flux ratio controller 326, and the controller 32 may be configured to give the target values of the torque and stator flux in a second torque and flux setting manner. In particular implementations, the speed regulator 325 may give a target value of the motor torque based on the actual speed and the target torque of the motorThe maximum torque flux ratio controller 326 may determine and target a minimum stator flux for the motor to have a target torque based on the target torque as a target value for the stator fluxOutput to the flux linkage comparison unit 328.

When the controller 32 determines a change in the power tool from the second load point to the first load point, the two switches S1 and S2 may be controlled to switch to the first switch state, giving the target values of the torque and the stator flux in a first torque and flux given manner.

In this embodiment, the torque comparison unit 327 may compare the target value and the actual value of the torque to determine the difference therebetween, and the flux linkage comparison unit 328 may compare the target value and the actual value of the stator flux linkage to determine the difference therebetween. The controller 32 may determine corresponding voltage vectors in the switching table 329 corresponding to the two differences and generate SVPWM control signals to control motor operation.

In this embodiment, the application conditions corresponding to the first load point and the second load point are not specifically limited. For example, the first load point may be a high-speed low-torque application condition, the second load point may be a low-speed high-torque application condition, the change from the first load point to the second load point may be a change from the high-speed low-torque application condition to the low-speed high-torque application condition, and the change from the second load point to the first load point may be a change from the low-speed high-torque application condition to the high-speed low-torque application condition.

In the second torque and flux linkage given mode, the target value of the stator flux linkage is equal to or less than the reference value of the stator flux linkage. The reference value is understood to be a setting value for the stator flux linkage among the parameters of the factory setting of the electric tool. And under the given mode of the first torque and the flux linkage, the target value of the stator flux linkage is larger than or equal to the reference value.

In this embodiment, the first torque and flux linkage given mode may also be referred to as a given mode in which the field weakening control can be performed on the motor at the time of field weakening given, and the second torque and flux linkage given mode may be referred to as a maximum torque flux ratio mode, i.e., a given mode in which the maximum output power of the motor is ensured.

The motor control also includes motor braking control, and typical motor braking may include coasting braking in which power is turned off, short-circuit braking in which the upper side switching element of the drive circuit is fully opened or the lower side switching element is fully opened to short-circuit the motor windings, and negative torque braking in which negative torque is controlled to be output by the motor.

In the control system 20 shown in fig. 4, the controller 22 may make the target value or the reference value of the torque output from the flux linkage and torque given unit 221 be equal to or less than zero, i.e., control the motor to brake with negative torque, in response to the brake signal. Or in response to the braking signal flux and torque given unit 221 increasing the target value of the stator flux to reduce the field weakening effect to gradually decrease the motor speed until zero.

In the control system 30 shown in fig. 8, the controller 32 may make the target value or the reference value of the torque output from the torque given unit 323 be zero or less in response to the braking signal, that is, control the motor to brake with negative torque. In one embodiment, controller 32 may also cause flux linkage giving unit 324 to increase the target value of the stator flux linkage in response to the braking signal, thereby reducing the flux weakening effect to gradually decrease the motor speed until zero. In the control system shown in fig. 8, the switches S1 and S2 are in the first switching state during the response of the brake signal by the controller 32, and the rotational speed regulator 325 and the maximum torque flux ratio controller 326 are electrically disconnected in the control system.

In the present embodiment, the user can input a brake signal through the operation assembly 14, such as a switch-off operation or a knob reset to an initial position or a trigger reset to an initial position, or the like.

In one embodiment, different braking modes can be used for braking at different stages of braking, for example, a sliding braking control mode is used at the initial stage of braking, then a given value of the stator flux is increased to quickly reduce the motor rotation speed, or the target of the stator flux is set to be less than or equal to zero to brake with negative torque. The application does not limit the braking mode adopted in different stages by dividing the braking stages.

For convenience of description, the control system shown in fig. 8 will be described below as an example of motor brake control. In the present embodiment, in response to the braking signal, the reference value of the torque output by the torque given unit 323 is zero or less, thereby controlling motor braking.

Although negative torque can rapidly brake the motor, there are problems such as negative torque braking can cause the bus voltage of the motor to rise, which can cause the motor to heat up severely or damage long-term powered electronic components in the control system. In order to avoid the occurrence of the above-mentioned problems,

During braking of the motor with a negative torque, the controller 32 may detect a dc bus voltage value of the electric tool, and when the voltage is equal to or greater than a first voltage threshold, the target value of the stator flux output by the flux linkage giving unit 324 may be increased, so that the kinetic energy of braking is rapidly dissipated in the motor, while maintaining accurate torque control. The first voltage threshold may be a threshold range of dc bus voltages, for example, any value within plus or minus 10% of the power supply voltage. In this embodiment, the motor is a low-power motor, the impedance of the motor is related to the corresponding rated current, the effect of the magnetic flux braking on the low-power motor is obvious, and the output power of the exemplary motor is less than or equal to 15kw, for example, 15kw,10kw,8kw,5kw, and the like.

In one embodiment, as shown in fig. 9, the control system 40 includes a power supply device 41, a controller 42, a detection module 43, a drive circuit 44, and a motor 45. In this embodiment, the control system 40 further includes a brake resistor 46, and a switching device 47. The controller 42 is identical to the controller 32 or 22 in the above embodiment, and may also include a torque and flux linkage given unit, a torque and flux linkage estimation unit, a torque and flux linkage comparison unit, and a switch table. The unit modules in the controller 42 will not be described in detail here. The detection module 43 can detect the voltage on the dc bus of the power tool and output the detected voltage to the controller 42.

The brake resistor 46 may be electrically disconnected from the stator windings of the motor 45 by a switching device 47. In the present embodiment, the controller 42 brakes the motor at a negative torque in response to the braking signal with a given value of torque of the torque and flux linkage given unit control motor being equal to or less than zero. When the dc voltage of the bus of the electric tool is equal to or greater than the first voltage threshold, the controller 42 may control the switching device 47 to be turned on so that the brake resistor 46 is connected to the power bus 48, and the bus voltage is consumed by the resistance heating. When the dc bus voltage falls below the first voltage threshold, the controller 42 may control the switching device 47 to open to disconnect the brake resistor 47 from the power bus 48. In this embodiment, the size and power of the brake resistor 46 need to be large enough to dissipate the power generated during braking as heat.

In one embodiment, as shown in fig. 10, the control system 50 includes a power supply device 51, a controller 52, a detection module 53, a driving circuit 54, and a motor 55. In this embodiment, the control system 50 further includes a super capacitor 56 and a control switch 57 capable of controlling whether the super capacitor 56 is connected to the power bus 58. In the process of controlling the motor to brake with negative torque, the controller 52 can control the control switch 57 to be in a closed state, the super capacitor 56 is connected to the power bus 58 and can absorb energy in the braking process, and when the motor operates normally, the controller 52 can control the control switch 57 to be disconnected, so that the super capacitor 56 is not connected to a circuit.

In one embodiment, the power tool 10 may be a fixed torque drill, that is, the power drill is operated with an output torque that does not exceed a predetermined constant torque, i.e., a target torque, beyond which the power drill is stopped. The direct torque control in the application can compare the actual torque of the motor estimated by the torque estimation unit with a set target value, and if the actual value is greater than or equal to the comparison value, the controller controls the motor to stop running. The manner in which the controller controls the motor to stop rotating may include at least one of coasting braking, negative torque braking, or short circuit braking in the above-described embodiments, which will not be described in detail herein.

In one embodiment, a method of optimizing the accuracy of direct torque control is also provided, for ease of presentation, in the following motor control illustrated by way of example in the control system of FIG. 4. In the present embodiment, the flux and torque giving unit 221 may set target values of the stator flux and torque, i.e., reference values, according to user inputs, and the flux and torque estimating unit 222 may estimate actual values of the stator flux and torque according to the operation parameters of the motor. The controller 22 does not calculate the difference value and generate the voltage vector immediately after determining the reference value and the actual value, but predicts the predicted value of the stator flux linkage and the motor torque at the next time based on the current actual value, and makes the difference between the predicted value and the target value instead of the actual value, thereby generating the voltage vector according to the difference value. In one embodiment, the voltage vector generating unit 224 may sequentially select one voltage vector or a switching state input driving circuit 23 according to the space voltage vector diagram shown in fig. 5 or the DTC switching state selection table shown in fig. 6 to control the motor 20 to rotate, and the detecting module 24 may detect the operation parameters of the motor 20, so that the flux linkage and torque estimating unit 222 determines a set of predicted values of the corresponding torque and stator flux linkage according to the current operation parameters, until all the voltage vectors in the switching table control the motor to operate and obtain the predicted values. The controller 22 may determine a set of predicted values closest to the reference value among all predicted values corresponding to all the voltage vectors, compare the set of closest predicted values with the target value, and determine a voltage vector for controlling the motor operation according to the comparison result, so as to control the motor operation. In one embodiment, after the controller 22 determines a set of predicted values closest to the reference value among all predicted values corresponding to all the voltage vectors, the voltage vector corresponding to the set of predicted values may be directly used as the voltage vector for controlling the motor to operate, and the motor may be controlled to operate.

In this embodiment, the method of determining the predicted value by the controller 22 may be referred to as an enumeration method, i.e. all voltage vectors in the voltage vector table are operated as control values to control the voltage one by one, so as to obtain the predicted value. In other embodiments, other prediction methods may be used to obtain predicted values of the motor torque and the stator flux, and compare the predicted values as actual values with target values, i.e., reference values, of the motor torque and the stator flux, and control the motor to operate according to the comparison result.

In some embodiments, the voltage vector generating unit in the controller can also adaptively adjust the values of the target torque and the target stator flux linkage by adopting at least one control mode of sliding mode control, fuzzy logic control and artificial neural network control, so as to optimize the accuracy of determining the voltage vector and improve the control accuracy of controlling the motor operation by adopting direct torque.

In one embodiment, the control system may drive the motor in different control modes during different phases of motor operation. The controller drives the motor in a first control manner when the power tool is in a first operating phase, and controls the drive circuit to drive the motor in a second control manner when the power tool is in a second operating phase. One of the first control manner or the second control manner is the direct torque control described in the above embodiment, and the other control manner is different from the direct torque control manner. That is, direct torque control and other control schemes may be employed in conjunction with controlling the motor operation at various stages of the power tool, such as direct torque control and vector control in combination or otherwise. The controller may determine whether the power tool is in the first operating phase or the second operating phase based on a load related parameter of the motor. For example, the controller may determine the current operating phase of the power tool based on at least one parameter of the phase current, voltage, rotational speed, torque, or acceleration of the motor. In one embodiment, the controller may also determine the stage of operation in which the power tool is operating based on parameters of the power device. For example, the controller may determine the current operating phase of the power tool based on at least one of the temperature, voltage, or current of the battery pack. In one embodiment, the working stage of the electric tool may be understood as the working condition of the electric tool, for example, a light load working condition, a medium load working condition, a heavy load working condition, an idle working condition, a rated load working condition, or the like, which are not listed herein.

In one embodiment, there may be more than one motor in the power tool, such as a hand propelled power tool, e.g., a hand propelled mower, a hand propelled snowplow; or a riding power tool, such as a riding mower, a riding vehicle, an all-terrain vehicle, or the like; or robotic tools, e.g., a mowing robot, a snowplow robot, etc. In one embodiment, the power tool is a garden tool, for example, comprising at least one of a self-propelled machine, a riding machine, an intelligent robot, a hand-propelled machine, a backpack machine, a hand-held machine, and a wheeled machine. In some large power tools there may be provided a first motor that provides the driving force for the road wheels and a second motor that provides the power for the functional elements. The two motors may be of the same type or of different types, for example one motor being a hub motor and one being a booster motor transmitting driving force through a gearbox.

The two motors in the gardening tool may respectively correspond to different driving circuits, such as the control system 60 shown in fig. 11, including: the power supply device 61, the control assembly 62, the first driving circuit 63, the first motor 64, the second driving circuit 65, and the second motor 66. The first driving circuit 63 is electrically connected to the first motor 64 for driving the first motor 64, and the second driving circuit 65 is electrically connected to the second motor 66 for driving the second motor 66. The control assembly 62 in the control system 40 may control the first drive circuit 63 in a first control manner and the second drive circuit 65 in a second control manner, wherein at least one of the two control manners is direct torque control. In this embodiment, the control unit 62 may include two controllers, i.e., the first controller 621 and the second controller 622, which may have the same hardware configuration, or may have different hardware configurations, for example, both controllers may use a dedicated control chip (for example, MCU, micro control unit, microcontroller Unit), or may integrate a memory such as the random access memory ROM (Random Access Memory) or the read only memory RAM (Read Only Memory), or integrate a timer, or the like.

The foregoing has shown and described the basic principles, principal features and advantages of the invention. It will be appreciated by persons skilled in the art that the above embodiments are not intended to limit the invention in any way, and that all technical solutions obtained by means of equivalent substitutions or equivalent transformations fall within the scope of the invention.

Claims

1. A power tool, comprising:

A housing for forming an accommodation space:

The motor is arranged in the accommodating space and comprises a stator and a rotor;

A functional element connected to an output shaft of the motor, drivable by the motor;

A power supply device for supplying electric power to the electric tool;

the driving circuit is electrically connected with the motor to drive the motor and comprises a plurality of switching elements;

A detection module configured to detect an operating parameter of the motor;

a controller electrically coupled to at least the drive circuit and the parameter detection module,

Wherein the controller comprises:

A flux linkage and torque given unit configured to give target values of motor torque and stator flux linkage;

a flux and torque estimation unit configured to calculate actual values of the motor torque and the stator flux from the operating parameters;

a flux linkage and torque comparison unit arranged to compare the target value and the actual value;

And a voltage vector generating unit configured to output a voltage vector according to a comparison result of the flux linkage and the torque comparing unit, so as to control a conduction state of a switching element in the driving circuit.

2. The power tool of claim 1, wherein the detection module includes a resistance observer for observing a stator resistance; the flux linkage and torque estimation unit is arranged to calculate an actual value of the stator flux linkage based on the stator resistance.

3. The electric power tool according to claim 1, wherein the voltage vector generation unit is configured to obtain the voltage vector by looking up a table based on the comparison result.

4. The power tool of claim 1, wherein the torque response time is less than or equal to 10ms.

5. The power tool of claim 2, further comprising a resistive cooling device for dissipating heat from the stator.

6. The power tool of claim 1, further comprising an operating component for obtaining user input; and a flux linkage and torque giving unit configured to give target values of the motor torque and stator flux linkage according to the user input.

7. The power tool of claim 6, wherein the operating assembly includes a speed governor.

8. The power tool of claim 7, wherein the speed adjustment mechanism comprises one of a switch, a trigger, a knob, and a slide mechanism.

9. The power tool of claim 1, wherein the functional element comprises at least one of a sanding element, a drilling element, a cutting element, a blowing element, a cleaning element, and a fastener.

10. The power tool of claim 1, wherein the power supply means comprises a battery pack removably connected to the power tool.

11. A power tool, comprising:

a motor including a stator and a rotor;

A power supply device for supplying electric power to the electric tool;

an operation component for acquiring user input;

A detection module configured to detect an operating parameter of the motor;

A controller electrically coupled to at least the drive circuit, the detection module, and the operational component;

The controller is configured to:

controlling a switching element in the driving circuit to change a conducting state according to the user input and the working parameter so as to drive the motor to operate;

the torque response time of the controller is less than or equal to 10 milliseconds.

12. The power tool of claim 11, wherein the controller employs direct torque control.

13. The power tool of claim 11, wherein the operating assembly comprises at least one of a power switch, a gear selection switch, and a smart detection element.

14. The power tool of claim 11, wherein the controller comprises: a flux linkage giving unit for outputting a reference value of flux linkage of the stator; a flux linkage estimation unit configured to estimate an actual value of flux linkage of the stator according to the operation parameter; the controller is configured to control the drive circuit to drive the motor in a closed-loop control manner based at least on a comparison of the flux linkage reference value and the actual value of the stator.

15. The power tool of claim 11, wherein the controller comprises: a torque setting unit for outputting a reference value of torque of the motor; a torque estimation unit configured to estimate an actual value of torque of the motor based on an operation parameter of the motor; and the controller generates a voltage vector in a hysteresis control mode at least according to the comparison result of the torque reference value and the actual value of the motor to control the driving circuit to drive the motor.

16. The power tool of claim 11, wherein the torque response time of the controller is less than or equal to 5 milliseconds.