Power tool and control method therefor

Abstract

A power tool, comprising: a housing and a functional member; a motor, configured to drive the functional member to operate; a power supply device, configured to at least supply power to the motor; and a controller, electrically connected to the motor and the power supply device and configured to control the operation of the motor. The controller is specifically configured to: during the operation of the motor, determine a real-time temperature of the motor at least on the basis of a structural parameter of the motor, a thermal parameter, and a real-time electrical parameter of the motor, and dynamically adjust a current control strategy of the motor on the basis of the real-time temperature and / or a change trend of the real-time temperature.

Description

Power tools and their control methods

[0001] This application claims priority to Chinese Patent Application No. 202411595291.3, filed with the Chinese Patent Office on November 8, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of power tool technology, and for example to a power tool and a control method thereof. Background Technology

[0003] Power tools, widely used in industrial and household applications such as landscaping and construction, are mostly driven by motors that power functional components on the output shaft to perform tasks such as cutting, fastening, and grinding. Some wheeled tools, in addition to the aforementioned motors driving the functional components, also include a motor driving the travel mechanism. The output performance of motors is significantly affected by temperature. Many types of power tools, and many operating conditions of power tools, require high-power motor output. The resulting temperature rise in the motor can lead to motor control malfunctions and damage. Therefore, it is necessary to monitor the motor temperature to avoid unnecessary overheating risks.

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

[0005] This application addresses or at least mitigates some or all of the aforementioned problems. Therefore, this application provides an electric tool and its control method.

[0006] An electric tool includes: a housing and a functional component; a motor configured to drive the functional component to operate; a power supply configured to supply power to at least the motor; and a controller electrically connected to the motor and configured to control the operation of the motor. The controller is specifically configured to: determine the real-time temperature of the motor during operation, based at least on the motor's structural parameters, thermal parameters, and real-time electrical parameters, and dynamically adjust the current control strategy of the motor based on the real-time temperature and / or the trend of real-time temperature changes.

[0007] In some embodiments, the real-time electrical parameters of the motor include one or more of the following: real-time current, real-time voltage, real-time speed, and real-time power.

[0008] In some embodiments, the thermal parameters of the motor include the thermal resistance coefficient and / or thermal capacity coefficient of one or more components within the motor; the thermal resistance coefficient and / or thermal capacity coefficient include the material type and / or mass and / or thermal conductivity of one or more of the permanent magnets, iron core, and windings within the motor, as well as the heat dissipation method of the motor.

[0009] In some embodiments, the structural parameters of the motor include one or more of the following: stator shape and dimensions, rotor shape and dimensions, number of slots, and number of pole pairs.

[0010] In some embodiments, the structural parameters of the motor include the specific components of the motor, which include the equivalent thermal resistance node, thermal capacity node, heat source node, and the connection relationship between the three.

[0011] In some embodiments, the controller is configured to determine the real-time temperature rise of the motor during operation based on structural parameters, thermal parameters, and real-time electrical parameters, and to dynamically adjust the current control strategy of the motor based on the real-time temperature rise and / or the trend of its change.

[0012] In some embodiments, the controller is configured to determine the real-time temperature of the motor during operation based on structural parameters, thermal parameters, real-time electrical parameters, and reference point temperature, and to dynamically adjust the current control strategy of the motor based on the real-time temperature and its changing trend.

[0013] In some embodiments, the controller is configured to limit one or more of the motor's current, speed, torque, and power when the real-time temperature exceeds a first threshold and the real-time temperature is trending upward.

[0014] In some embodiments, the controller is configured to periodically calculate the real-time temperature of the motor and determine the current temperature flag state based on the numerical relationship between the real-time temperature calculated in the current cycle and the first threshold, the second threshold, and the real-time temperature calculated in the previous cycle; the second threshold is greater than the first threshold, and the temperature flag has at least three states: "0", "1", and "2".

[0015] In some embodiments, the controller is configured to periodically maintain, or increment or decrement a control target value in steps based on the state of the current temperature flag bit. The control target value includes a current target value and / or a speed target value used for motor operation control.

[0016] In some embodiments, the controller is configured to set the temperature flag to "0" if the real-time temperature calculated in the current cycle is lower than a first threshold; and / or set the temperature flag to "2" if the real-time temperature calculated in the current cycle is higher than a second threshold or higher than the first threshold and shows an increasing trend; and / or set the temperature flag to "1" if the real-time temperature calculated in the current cycle is higher than the first threshold but lower than the second threshold or higher than the first threshold and shows a decreasing trend.

[0017] In some embodiments, the controller is configured to set a control target value that increments in steps, with a preset value or a user-defined value as the upper limit, when the current temperature flag is "0".

[0018] In some embodiments, the controller is configured to set the control target value to decrease in steps when the current temperature flag is "2"; and / or, the controller is configured to set the control target value to decrease in steps when the current temperature flag is "0" and the step size of each decrease is less than the step size of each decrease when the temperature flag is "2".

[0019] A control method for an electric tool includes: during the operation of the electric tool's motor, the controller of the electric tool acquires the real-time electrical parameters of the motor; the controller determines the real-time temperature of the motor based on the motor's structural parameters, thermal parameters, and real-time electrical parameters, and dynamically adjusts the current control strategy of the motor based on the real-time temperature and / or the trend of real-time temperature changes.

[0020] An electric tool includes: a housing and a functional component; a motor including a stator assembly and a rotor assembly, configured to drive the functional component to operate; a power supply device configured to supply power to at least the motor; and a controller electrically connected to the motor and configured to control the operation of the motor. The electric tool further includes: a temperature sensor disposed at a first location within the electric tool and configured to detect a first real-time temperature at the first location within the electric tool; the controller is also electrically connected to the temperature sensor and is specifically configured to: acquire the first real-time temperature during motor operation, and determine a second real-time temperature at a second location within the motor, based at least on the first real-time temperature and real-time electrical parameters of the motor; the second location is different from the first location.

[0021] In some embodiments, the second position is a non-fixed position during motor operation, and the second position is located on the rotor assembly of the motor.

[0022] In some embodiments, the first position is a fixed position during motor operation, and the first position is located on the stator assembly of the motor.

[0023] In some embodiments, the first real-time temperature is the casing temperature or the ambient temperature.

[0024] In some embodiments, the controller is configured to determine a second real-time temperature based on a first real-time temperature and real-time electrical parameters, as well as structural and thermal parameters corresponding to the heat conduction process from the first position to the second position.

[0025] In some embodiments, the controller is also configured to dynamically adjust the current control strategy of the motor based on the second real-time temperature and / or the trend of the second real-time temperature change.

[0026] A control method for an electric tool includes: a temperature sensor disposed at a first position within the electric tool detects a first real-time temperature at the first position; during the operation of the electric tool's motor, a controller of the electric tool acquires real-time electrical parameters of the motor and the first real-time temperature detected by the temperature sensor; the controller determines a second real-time temperature at a second position within the motor based at least on the first real-time temperature and the real-time electrical parameters; the second position is different from the first position. Attached Figure Description

[0027] Figure 1 is a perspective view of a power tool (electric circular saw) as an embodiment of this application;

[0028] Figure 2 is a perspective view of an electric tool (riding lawnmower) as another embodiment of this application;

[0029] Figure 3 is a schematic diagram of the electrical control principle of the power tool shown in Figures 1 and 2 in one embodiment;

[0030] Figure 4 is a schematic diagram of the electrical control principle of the power tool shown in Figures 1 and 2 in another embodiment;

[0031] Figure 5 is an exploded view of the motor in the power tool shown in Figures 1 and 2;

[0032] Figure 6 is the equivalent thermal circuit model of the motor in one embodiment of this application;

[0033] Figure 7 is a specific flow chart of a power tool control method as an embodiment of this application;

[0034] Figure 8 is another specific flow chart of the control method of the power tool shown in Figure 7;

[0035] Figure 9 is a test diagram of the motor speed and temperature of an electric tool under the control of a controller, as an embodiment of this application;

[0036] Figure 10 is a flowchart of a power tool control method according to an embodiment of this application;

[0037] Figure 11 is a flowchart of a control method for an electric tool according to another embodiment of this application. Detailed Implementation

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

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

[0040] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent three cases: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this application generally indicates that the preceding and following related objects have an "and / or" relationship.

[0041] In this application, the terms "connection," "combination," "coupling," and "installation" can refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without the need for an intermediary, while an indirect connection refers to two parts or components each being connected to at least one intermediary, with the connection achieved through the intermediary. Furthermore, "connection" and "coupling" are not limited to physical or mechanical connections or couplings, but can also include electrical connections or couplings.

[0042] In this application, those skilled in the art will understand that relative terms (e.g., “about,” “approximately,” “basically,” etc.) used in conjunction with quantities or conditions are to include the values ​​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 associated with the particular value due to manufacturing, assembly, use, etc. Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. Furthermore, “basically” when expressing relative angular relationships (e.g., substantially parallel, substantially perpendicular) may refer to a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) added to or subtracted from the indicated angle.

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

[0044] In this application, the directional terms "upper," "lower," "left," "right," "front," and "rear" are used to describe the orientation and positional relationships shown in the accompanying drawings and should not be construed as limiting the embodiments of this application. Furthermore, in the context, it should be understood that when an element is mentioned as being connected "upper" or "lower" to another element, it can be directly connected to the other element "upper" or "lower," or indirectly connected through an intermediate element. It should also be understood that directional terms such as upper side, lower side, left side, right side, front side, and rear side not only represent positive orientation but can also be understood as lateral orientation. For example, "below" can include directly below, lower left, lower right, lower front, and lower rear.

[0045] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. When using the unit "controller," "processor," "central processing unit," "CPU," or "MCU" to perform a specific function, unless otherwise stated, these functions may be performed by a single or multiple of the aforementioned units.

[0046] In this application, the terms "device," "module," or "unit" are used to describe devices that can be implemented in hardware or software to perform a specific function.

[0047] In this application, the terms “calculation,” “judgment,” “control,” “determine,” “identify,” etc., refer to the operation and process of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0048] The technical solution proposed in this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] Figures 1 and 2 illustrate the power tool 100 used as an embodiment in this application. The power tool 100 shown in Figure 1 is a circular saw 100a, and the power tool 100 shown in Figure 2 is a ride-on lawnmower 100b. In other embodiments, the power tool 100 may also be other types of handheld power tools such as jigsaws, reciprocating saws, electric drills, and impact wrenches, or table-type tools such as miter saws and table saws, or outdoor power equipment such as lawnmowers, snowplows, and all-terrain vehicles. It is understood that the power tool 100 using the technical solution of this application is not limited to the circular saw 100a, nor is it limited to the tool categories described above.

[0050] Referring to Figures 1 and 2, the power tool 100 includes a housing 10 and functional components 20. The housing 10 forms the main exterior of the power tool 100, connecting, supporting, and fixing other components, and its interior provides a accommodating space for these components. The functional components 20 are the parts in the power tool 100 that actually perform cutting, fastening, grinding, and other operations. For example, in the case of a circular saw 100a, its functional component 30 is a circular saw blade; in the case of a ride-on lawnmower 100b, its functional component 30 is a blade disc; and in other power tools 100, the functional component 30 can also be a chain, drill bit, etc. In some embodiments, the power tool 100 also includes an operating component 110, which can be a button, trigger, or other means located in the housing 10 for the user to start / stop the tool, select torque / speed, etc. Of course, the operating component 110 can also be an electronic component such as a signal transceiver, which receives user commands via communication to clarify the user's "operation."

[0051] Referring to Figure 3, in addition to the housing 10 and functional components 20, the power tool 100 also includes a motor 30, a power supply device 40, and a controller 50. The motor 30 is the prime mover in the power tool 100, and its motor shaft rotation can directly or indirectly drive the functional components 20 to perform operations. In some embodiments, the motor 30 of power tools 100 such as handheld or benchtop tools only includes the working motor that drives the aforementioned functional components 20. In some embodiments, the motor 30 of power tools 100 such as lawnmowers and snowplows includes the aforementioned working motor, and also includes a drive motor that drives the wheels, tracks, or other walking components. In some embodiments, outdoor work vehicles such as farm vehicles and golf carts only include the aforementioned drive motor. In some embodiments, the motor 30 is a three-phase motor. In some embodiments, the motor 30 is a brushless motor. In some embodiments, the motor 30 is a synchronous motor. In some embodiments, the motor 30 is a hub motor.

[0052] The power supply device 40 is capable of providing electrical energy to the motor 30, and may also supply power to the controller 50 and / or other related circuits. For example, the temperature sensor 60, described later, may also be powered by the power supply device 40. In some embodiments, the power supply device 40 is a battery pack, which is detachably connected to the power tool 100, and the housing 10 may be provided with a battery mounting portion for mounting the power supply device 40. In some embodiments, the power supply to the power tool 100 may also be achieved using mains power, AC power, or a power adapter or transformer, rectifier, and voltage regulator circuit.

[0053] The controller 50 can be an MCU (Microcontroller Unit), ARM (Advanced Reduced Instruction Set Computing Machine), DSP (Digital Signal Processor), etc. It is at least electrically connected to the motor 30, and in the case of non-independent power supply, it is also electrically connected to the power supply device 40. It can run relevant control programs and output control signals to the motor 30 to make the motor 30 operate correctly in the intended manner. Typically, a drive device such as a three-phase inverter bridge or an integrated drive chip is also connected between the controller 50 and the motor 30. The control signal output by the controller 60 is ultimately converted into a drive signal for the actual motor 30 through the drive device. In some embodiments, the control signal is a PWM (Pulse Width Modulation) signal, and the drive signal is a three-channel approximately sinusoidal wave signal with a 120° phase difference.

[0054] Following on from the previous point, to ensure the correct and safe operation of power tools, it is necessary to monitor the motor temperature. Currently, most related technologies use sensors embedded in the motor stator to directly obtain the motor temperature. However, this approach has several drawbacks: firstly, it increases the cost and manufacturing difficulty of additional components; secondly, sensor failure poses a risk; and thirdly, there may be significant temperature differences between different parts of the motor, making it inaccurate to characterize the motor temperature solely with stator temperature. Furthermore, it is difficult to attach sensors to components such as the rotor or some hidden internal locations, making it challenging to measure the temperature at target locations within the motor. In addition, the current technology's criterion of simply comparing the measured temperature to an upper temperature threshold and shutting down for protection when the threshold is exceeded is not intelligent enough and can negatively impact the continuity and accuracy of power tool operation.

[0055] In one alternative embodiment of this application, the controller 50 in the power tool 100 can acquire real-time electrical parameters of the motor 30 during operation of the motor 30, i.e., during the operation of the power tool 100. Based on these real-time electrical parameters and the known structural and thermal parameters of the motor 30, the controller calculates and determines the real-time temperature of the motor 30. Then, based on the calculated real-time temperature and the changing trend of the motor 30's real-time temperature, the controller dynamically adjusts the current motor 30 control strategy. The real-time electrical parameters acquired by the controller 50 may include one or more parameters, and the structural and thermal parameters of the motor 30 may also include one or more parameters. The real-time electrical parameters are currently measured parameters, while the structural and thermal parameters may be preset parameters, such as those tested or calculated in advance. The controller 50 employs different motor 30 control strategies to control the parameters of the motor 30, such as current, speed, and torque, to change linearly or non-linearly, and with increasing or decreasing trends, towards different target values. The motor 30 control strategy may involve target current values, target speed values, current thresholds, speed thresholds, etc., and the parameters associated with the motor 30 control strategy may differ under different motor 30 control methods, such as FOC and six-step commutation. For example, the motor 30 control strategy may also involve PID regulator parameters, PWM duty cycle, SVPWM modulation ratio, etc. The relevant descriptions should be understandable to those skilled in the art and will not be elaborated further. In some embodiments, the power tool 100 also includes detection devices for detecting various real-time electrical parameters of the motor 30, including but not limited to speed detectors and motor current detectors, which can be implemented using sensors.

[0056] Specifically, the controller 50 can run a predetermined function, using the real-time electrical parameters of the motor 30 as input parameters to obtain the current real-time temperature of the motor 30 as the output. This function mathematically simulates the heat conduction process inside the motor 30, using both structural and thermal parameters of the motor 30 as fixed parameters. This function has several possible implementation methods. The structural parameters of the motor 30 may include one or more of the following: the material type of the permanent magnets, stator and rotor cores, and windings; the stator shape and dimensions; the rotor shape and dimensions; the number of motor slots; and the number of motor pole pairs. These structural parameters relate to the specific structural composition of the motor 30, used to determine the components of the motor 30 and the heat transfer relationships between them during function construction. Based on the characterization of the components and heat transfer relationships of the motor 30 by the structural parameters, thermal parameters such as thermal capacity coefficient and thermal resistance coefficient can be used to determine the numerical relationships of heat transfer between the components of the motor 30 during function construction, thereby clarifying all coefficients of electrical parameters not involved in the heat conduction process. In some embodiments, structural parameters are also used in the calculation of coefficients that do not involve electrical parameters, such as the thermal capacity coefficient and / or thermal resistance coefficient of various components within the motor 30. After the temperature of the motor 30 is calculated in real time, the controller 50 will use the real-time temperature and / or the trend of its change as a reference to adjust the current control strategy of the motor 30 in real time, controlling the current, speed, torque, etc. of the motor 30 to change in accordance with the intended manner of the new control strategy.

[0057] In some embodiments, the controller 50 can calculate the real-time temperature rise of the motor 30 based on the aforementioned structural parameters, thermal parameters, and real-time electrical parameters. The real-time temperature rise can be the temperature difference between the current motor 30 temperature and a reference point temperature. Based on the current real-time temperature rise of the motor 30, and / or based on the current real-time temperature rise of the motor 30 and the trend of its change determined by comparing it with the real-time temperature rise at one or more previous times, the current control strategy of the motor 30 can be adjusted. In some embodiments, the reference point temperature can be assumed to be a constant value. In other embodiments, in addition to the aforementioned structural parameters, thermal parameters, and real-time parameters, the controller 50 also acquires and calculates the real-time temperature of the motor 30 based on a measured reference point temperature. Based on the current real-time temperature of the motor 30 and the trend of its change determined by comparing it with the real-time temperature at one or more previous times, the current control strategy of the motor 30 can be adjusted. In some embodiments, the reference point temperature can be the casing temperature or the ambient temperature. The above embodiment eliminates the need to add a temperature sensor 60 to detect the temperature of the motor 30, or the temperature measured by the existing temperature sensor 60 located at any position in the power tool 100 can be used as a reference point temperature, so that the dynamic adjustment closed loop of the motor 30 control strategy has real-time updated temperature input parameters.

[0058] In some embodiments, the controller 50 can construct a thermal path model simulating the heat conduction process within the motor 30 based on the aforementioned structural parameters, thermal parameters, and real-time electrical parameters. The structural parameters include nodes corresponding to the various components within the motor 30 and the connection relationships between nodes corresponding to the heat transfer relationships between components within the motor 30. Specifically, nodes may include heat source nodes, thermal resistance nodes, and thermal capacity nodes. The number of nodes of each type can be one or more. The structural parameters may also include one or more of the following: the stator shape and dimensions, the rotor shape and dimensions, the number of motor slots, and the number of motor pole pairs, to calculate the correlation coefficients of the aforementioned nodes in conjunction with the thermal parameters. The thermal parameters include the thermal capacity coefficient and thermal resistance coefficient of the nodes, which at least indicate the thermophysical properties of the aforementioned thermal capacity nodes and thermal resistance nodes. Specifically, the thermal parameters may include one or more of the following: the material type, mass, thermal conductivity of one or more of the permanent magnets, core, and windings within the motor 30, and one or more of the specific heat conduction methods (air cooling / liquid cooling) of the motor 30. Real-time electrical parameters include one or more of the following: real-time current (phase current, bus current, etc.), real-time voltage (phase voltage, bus voltage, etc.), real-time speed, and real-time power (input power, power loss, etc.) of the motor 30. These parameters at least indicate the current real-time thermophysical performance of the aforementioned heat source nodes. Understandably, the node type, number, and connection relationships correspond to the specific structural composition of the motor 30. Figure 6 shows a thermal circuit model corresponding to a motor 30, where T1 to T3 are the real-time temperatures at three different locations within the motor 30 under test, and T0 can be the reference point temperature.

[0059] In some embodiments, when the calculated real-time temperature of the motor 30 exceeds a first threshold and the current temperature of the motor 30 shows an increasing trend compared to the previous temperature, the controller 50 can control and limit one or more of the current, speed, and power of the motor 30. Specifically, the controller 50 can periodically calculate the real-time temperature of the motor 30 and periodically adjust the motor 30 control strategy. The temperature calculation period and the strategy adjustment period can be equal or unequal. Taking equal periods as an example, that is, temperature calculation and strategy adjustment are performed sequentially within one period. When the current period arrives, the controller 50 first calculates the current real-time temperature of the motor 30 based on the currently measured real-time electrical parameters of the motor 30. If the real-time temperature of the current period exceeds the first threshold and the real-time temperature of the motor 30 in the current period is higher than the real-time temperature of the motor 30 in the previous period, the controller 50 controls one or more of the current, speed, power, and other control quantities related to the temperature rise of the motor 30 to decrease. For example, the target current or speed value used for controlling the operation of motor 30 can be reduced by one step. In the next cycle, the actual current or speed of motor 30 will decrease by one step compared to the current cycle under this control strategy. Alternatively, the current or speed threshold used for controlling the operation of motor 30 can be reduced by one step, causing the temperature of motor 30 to decrease accordingly, and then detection and judgment will be performed again in the next cycle. The following text mainly uses the target current and speed values ​​as relevant control quantities for illustrative purposes. However, it is understandable that the direct control quantities involved in the strategy may differ under different control methods.

[0060] In some embodiments, referring to Figures 7 and 8, the controller 50 is provided with a first threshold. When the real-time temperature of the current motor 30 exceeds the first threshold and shows an increasing trend, the controller 50 sets the temperature flag to position 2. Optionally, when the real-time temperature of the current motor 30 exceeds the first threshold but does not show an increasing trend, the controller 50 sets the temperature flag to position 1. Optionally, when the real-time temperature of the current motor 30 does not exceed the first threshold, the controller 50 sets the temperature flag to position 0. Alternatively, the controller 50 is provided with a first threshold and a second threshold, both of which are temperature thresholds, and the first threshold is less than the second threshold. The first threshold can be the upper limit of the risk-free motor temperature, and the second threshold can be the upper limit of the motor temperature within the acceptable risk range. The controller 50 sets the temperature flag to position 2 when the real-time temperature of the current motor 30 exceeds the second threshold. And / or, the controller 50 sets the temperature flag to position 1 when the real-time temperature of the current motor 30 exceeds the first threshold but does not exceed the second threshold. And / or, the controller 50 sets the temperature flag to position 0 when the real-time temperature of the current motor 30 does not exceed the first threshold. When dynamically adjusting the control strategy of the motor 30, the controller 50 can adjust the values ​​of control targets such as the target current or target speed of the motor 30 based on the state of the temperature flag bit. This includes increasing or decreasing the value of the control target by steps, with a preset value or a user-defined value as the upper limit. The step size corresponding to different states of the temperature flag bit can be different. As shown in Figure 8, in some embodiments, when the temperature flag bit is 2, the controller 50 decreases the target current or target speed value of the motor 30 by steps. In some embodiments, when the temperature flag bit is 1, the controller 50 decreases the target current or target speed value of the motor 30 by steps. The step size for decreasing the target value is different when the temperature flag bit is 1 and 2; the step size for a single decrease when the temperature flag bit is 2 can be greater than the step size for a single decrease when the temperature flag bit is 1. In some embodiments, when the temperature flag bit is 0, the controller 50 increases the target current or target speed value by steps, with the preset value or user-defined value as the upper limit.

[0061] Specifically, referring to Figure 9, assuming the user-set speed of motor 30 after power tool 100 starts is 8000 rpm, the calculated real-time temperature of motor 30 is currently below the threshold of 120°C. Controller 50 sets the target speed of motor 30 to 8000 rpm during motor 30 operation control. Power tool 100 begins operation. During the time period [0, 5 min], the real-time temperature of motor 30, calculated based on its real-time electrical parameters, increases non-linearly but remains below the threshold. With the target speed set at 8000 rpm, controller 50 controls motor 30 to increase its speed from 0 to 8000 rpm and maintain it. During the time period [5 min, 50 min], the real-time temperature calculated based on the motor 30's real-time electrical parameters will exceed the threshold and show an increasing trend compared to the previous real-time temperature. Based on this judgment, controller 50 will decrease the target speed of motor 30 from 8000 rpm to 7000 rpm. By decreasing the target speed value, the temperature of motor 30 is immediately pulled back and maintained at approximately 120°C. This temperature remains in a dynamic equilibrium, thus mitigating the risk of overheating during prolonged continuous operation. Furthermore, during the time period [5 min, 6 min], if the real-time temperature calculated based on the real-time electrical parameters of motor 30 exceeds the threshold and continues to increase, controller 50 will control the target speed value of motor 30 to decrease with a larger step. During the time period [6 min, 12 min], if the real-time temperature calculated based on the real-time electrical parameters of motor 30 exceeds the threshold but shows a downward trend, controller 50 will control the target speed value of motor 30 to decrease with a smaller step. After 12 minutes, the speed of motor 30 enters a dynamic equilibrium state. During the time period [50 min, 100 min], the power tool 100 bears a heavier load than in previous time periods, i.e., operates under heavy load conditions. The real-time temperature calculated based on the real-time electrical parameters of motor 30 will exceed the threshold and show an increasing trend compared to before. Based on this judgment, controller 50 will decrease the target speed of motor 30 from 7000 rpm to 4500 rpm. Through this decrease in the target speed, the temperature of motor 30 is immediately pulled back and maintained at approximately 120℃. This temperature remains in a dynamic equilibrium, thus mitigating the risk of overheating under heavy loads and other specific operating conditions. The specific control process will not be elaborated further. It is understood that the threshold of 120℃ can be the first threshold described above; this value is for illustrative purposes only, and other values, such as 80℃ or 70℃, can be used in actual applications.

[0062] Correspondingly, this application also proposes a control method for a power tool 100. Referring to Figure 10, which is a flowchart of the control method, the method specifically includes the following steps:

[0063] S1010, during the operation of the motor 30 of the power tool 100, the controller 50 of the power tool 100 acquires the real-time electrical parameters of the motor 30.

[0064] S1020, the controller 50 determines the real-time temperature of the motor 30 based on the structural parameters, thermal parameters and real-time electrical parameters of the motor 30;

[0065] S1030, the controller 50 dynamically adjusts the current control strategy of the motor 30 based on the real-time temperature and / or the real-time temperature change trend.

[0066] In another alternative embodiment of this application, following the preceding text, as shown in FIG3, the power tool 100, in addition to including a housing, functional components, a motor 30, a power supply device, and a controller 50, also includes a temperature sensor 60 disposed at a first position within the power tool 100. This temperature sensor 60 can directly detect a first real-time temperature at that first position. The controller 50 of the power tool 100 is also electrically connected to the temperature sensor 60 to obtain the detected first real-time temperature, and during the operation of the motor 30, i.e., during the operation of the power tool 100, it acquires the real-time electrical parameters of the motor 30. Based at least on the aforementioned first real-time temperature and real-time electrical parameters, a second real-time temperature at a second position within the motor 30 is calculated and determined. The first position can be located at any position within the power tool 100, and the second position is located inside the motor 30. In some embodiments, the first position is a fixed position during the operation of the motor 30, and the second position is a non-fixed position during the operation of the motor 30. Referring to Figure 5, the motor 30 includes at least a stator assembly 31 and a rotor assembly 32. The stator assembly 31 may include a stator core and stator coils, and the rotor assembly 32 may include a rotor core and permanent magnets (rotor magnets). In some embodiments, the second position may be located in the rotor assembly 32, for example, in the rotor core. In some embodiments, the first position may be located in the stator assembly 31, for example, in the stator core. In some embodiments, the first position may be located on the housing of the power tool 100 or in its internal space, and the first real-time temperature may be the housing temperature or the ambient temperature. This embodiment can utilize the first real-time temperature measured by the temperature sensor 60 at a location within the power tool 100 where it is easy to embed and install a sensor, combined with the real-time electrical parameters of the motor 30, to calculate the second real-time temperature at a location within the motor 30 where it is difficult to install a sensor and where sensor data is difficult to transmit to the controller 50. This allows for obtaining real-time temperatures at more or more critical locations within the motor 30, including but not limited to calculating the rotor temperature from the stator temperature, which helps to achieve more accurate and reliable motor 30 operation control.

[0067] In some embodiments, the controller 50 determines the second real-time temperature based on the first real-time temperature, the real-time electrical parameters of the motor 30, and the structural and thermal parameters corresponding to the heat conduction process from the first position to the second position. In some embodiments, during the operation of the motor 30, the controller 50 dynamically adjusts the current control strategy of the motor 30 based at least on the currently calculated second real-time temperature and / or the trend of its change, in order to utilize the second real-time temperature to control the operation of the motor 30 more accurately and reliably. It is understood that specific implementations of the related embodiments can be referred to the foregoing description without conflict.

[0068] Correspondingly, this application also proposes a control method for a power tool 100. Referring to Figure 11, which is a flowchart of the control method, it specifically includes the following steps:

[0069] S1110, a temperature sensor 60 disposed in the power tool 100 at a first position detects a first real-time temperature at the first position;

[0070] S1120, during the operation of the motor 30 of the power tool 100, the controller 50 of the power tool 100 acquires the real-time electrical parameters of the motor 30 and the first real-time temperature detected by the temperature sensor 60.

[0071] S1130, the controller 50 determines a second real-time temperature at a second position within the motor 30 based at least on a first real-time temperature and real-time electrical parameters; the second position is different from the first position.

[0072] Furthermore, in some embodiments, referring to FIG4, the controller 50 may include a speed loop, a current distribution unit, a first current loop, a second current loop, a current conversion unit, a voltage conversion unit, and a vector modulation unit. The detection device may include a current detection module and a position / speed detection module. The speed loop is set with a target speed value n0 and is connected to the speed detection module to obtain the actual speed value n of the motor 30 it detects. The speed loop determines the current target current value Is0 of the motor 30 based on the target speed and the actual speed value n.

[0073] The current distribution unit is connected to the aforementioned speed loop and distributes the direct-axis target current Id0 and quadrature-axis target current Iq0 based on the target current Iso. The current conversion unit is connected to the current detection module and can acquire the phase currents Iu, Iv, and Iw of the three-phase windings and convert them from the three-phase stationary coordinate system to the two-phase rotating coordinate system to obtain the actual direct-axis current Id and the actual quadrature-axis current Iq. The first current loop is connected to the aforementioned current distribution unit and current conversion unit and can acquire and determine the first regulating voltage Ud based on the aforementioned direct-axis target current Id0 and actual direct-axis current Id. The second current loop is connected to the aforementioned current distribution unit and current conversion unit and can acquire and determine the second regulating voltage Uq based on the aforementioned quadrature-axis target current Iq0 and actual quadrature-axis current Iq.

[0074] The voltage conversion unit is connected to the first current loop and the second current loop, and can acquire the first regulating voltage Ud and the second regulating voltage Uq, and convert them from a two-phase rotating coordinate system to a two-phase stationary coordinate system to obtain the first voltage control quantity Ua and the second voltage control quantity Ub. The vector modulation unit is connected to the voltage conversion unit, and can acquire the first voltage control quantity Ua and the second voltage control quantity Ub, and modulate the first voltage control quantity Ua and the second voltage control quantity Ub to generate corresponding pulse width modulation signals and output them to the driving device.

[0075] The advantages of this application are that it extrapolates the real-time temperature of the motor through the real-time electrical parameters of the motor, and dynamically adjusts the current control strategy of the motor based on the real-time temperature and its changing trend. Firstly, a temperature sensor may not need to be installed inside the motor, or the temperature sensor may be installed on easily bonded, non-rotating parts, thereby reducing the processing difficulty and related costs caused by detecting the real-time temperature of the motor. Secondly, relying on the real-time temperature control strategy to form a closed loop, the motor can ultimately be stably kept in a risk-free temperature range, reliably ensuring the operation of the power tool.

[0076] The foregoing has shown and described the basic principles, main features, and advantages of this application. Those skilled in the art should understand that the above embodiments do not limit this application in any way, and all technical solutions obtained by equivalent substitution or equivalent transformation fall within the protection scope of this application.

Claims

1. An electric tool, comprising: Housing and functional components; An electric motor is configured to drive the functional components to operate; The power supply device is configured to supply power to at least the motor; A controller, electrically connected to the motor, is configured to control the operation of the motor; Specifically, the controller is configured to: determine the real-time temperature of the motor based at least on the motor's structural parameters, thermal parameters, and real-time electrical parameters during the motor's operation, and dynamically adjust the motor's current control strategy based on the real-time temperature and / or the trend of the real-time temperature change.

2. The power tool according to claim 1, wherein, The real-time electrical parameters of the motor include one or more of the following: real-time current, real-time voltage, real-time speed, and real-time power.

3. The power tool according to claim 1, wherein, The thermal parameters of the motor include the thermal resistance coefficient and / or thermal capacity coefficient of one or more components within the motor; the thermal resistance coefficient and / or the thermal capacity coefficient include the material type and mass of one or more of the permanent magnets, iron core, and windings within the motor, as well as one or more of the heat dissipation methods of the motor.

4. The power tool according to claim 1, wherein, The structural parameters of the motor include one or more of the following: stator shape and dimensions, rotor shape and dimensions, number of slots, and number of pole pairs.

5. The power tool according to claim 1, wherein, The controller is configured to determine the real-time temperature rise of the motor during operation based on the structural parameters, the thermal parameters, and the real-time electrical parameters, and to dynamically adjust the current control strategy of the motor based on the real-time temperature rise and / or the trend of the real-time temperature rise.

6. The power tool according to claim 1, wherein, The controller is configured to determine the real-time temperature of the motor during operation based on the structural parameters, the thermal parameters, the real-time electrical parameters, and the reference point temperature, and to dynamically adjust the current control strategy of the motor based on the real-time temperature and the trend of its change.

7. The power tool according to claim 1, wherein, The controller is configured to limit one or more of the motor's current, speed, torque, and power when the real-time temperature exceeds a first threshold and the real-time temperature is increasing.

8. The power tool according to claim 7, wherein, The controller is configured to periodically calculate the real-time temperature of the motor, and determine the current temperature flag state based on the numerical relationship between the real-time temperature calculated in the current cycle and the first threshold, the second threshold, and the real-time temperature calculated in the previous cycle; the first threshold is less than the second threshold, and the temperature flag has at least three states: "0", "1", and "2".

9. The power tool according to claim 8, wherein, The controller is configured to periodically maintain, or increment or decrement a control target value in steps, based on the state of the current temperature flag, the control target value including a current target value and / or a rotational speed target value.

10. The power tool according to claim 8, wherein, The controller is configured to set the temperature flag to "0" if the real-time temperature calculated in the current cycle is lower than the first threshold; and / or set the temperature flag to "2" if the real-time temperature calculated in the current cycle is higher than the second threshold or higher than the first threshold and shows an increasing trend; and / or set the temperature flag to "1" if the real-time temperature calculated in the current cycle is higher than the first threshold but lower than the second threshold or higher than the first threshold and shows a decreasing trend.

11. The power tool according to claim 9 or 10, wherein, The controller is configured to, when the current temperature flag is "0", set the control target value to increase incrementally with a preset value or a user-defined value as the upper limit.

12. The power tool according to claim 9 or 10, wherein, The controller is configured to, when the current temperature flag is "2", set the control target value to decrease in steps; and / or, when the current temperature flag is "1", set the control target value to decrease in steps, with each step being smaller than the step size when the temperature flag is "2".

13. The power tool according to claim 1, further comprising: A temperature sensor is disposed at a first location within the power tool and configured to detect a first real-time temperature at the first location; The controller is also electrically connected to the temperature sensor. The controller is configured to acquire the first real-time temperature during the operation of the motor, and determine a second real-time temperature at a second position inside the motor based at least on the first real-time temperature and the real-time electrical parameters of the motor; the second position is different from the first position.

14. The power tool according to claim 13, wherein, The first real-time temperature is either the casing temperature or the ambient temperature.

15. The power tool according to claim 13, wherein, The first position is a fixed position during the operation of the motor; the second position is a non-fixed position during the operation of the motor.

16. A power tool, comprising: Housing and functional components; An electric motor, including a stator assembly and a rotor assembly, is configured to drive the functional components to operate; The power supply device is configured to supply power to at least the motor; A controller, electrically connected to the motor, is configured to control the operation of the motor; The power tool also includes: A temperature sensor is disposed at a first location within the power tool and configured to detect a first real-time temperature at the first location; The controller is also electrically connected to the temperature sensor, and the controller is specifically configured to: acquire the first real-time temperature during the operation of the motor, and determine a second real-time temperature at a second position inside the motor based at least on the first real-time temperature and the real-time electrical parameters of the motor; the second position is different from the first position.

17. The power tool according to claim 16, wherein, The second position is a non-fixed position during the operation of the motor, and the second position includes the position located on the rotor assembly of the motor; the first position is a fixed position during the operation of the motor, and the first position includes the position located on the stator assembly of the motor.

18. The power tool according to claim 16, wherein, The controller is configured to determine the second real-time temperature based on the first real-time temperature, the real-time electrical parameters, and the structural and thermal parameters corresponding to the heat conduction process from the first position to the second position.

19. The power tool according to claim 16, wherein, The controller is also configured to dynamically adjust the current control strategy of the motor based on the second real-time temperature and / or the changing trend of the second real-time temperature.

20. A control method for an electric tool, wherein, The control method includes: A temperature sensor located at a first position within the power tool detects a first real-time temperature at that position. During the operation of the power tool's motor, the power tool's controller acquires the motor's real-time electrical parameters and the first real-time temperature detected by the temperature sensor. The controller determines a second real-time temperature at a second position within the motor, based at least on the first real-time temperature and the real-time electrical parameters. The second position is different from the first position.

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