Electric mower and electric tool

Abstract

An electric tool, comprising: a cutting assembly (120), comprising at least one cutting blade (122) and a cutting motor (M1) driving the cutting blade (122) to perform a cutting action; a power supply apparatus (170), which is at least used to supply power to the cutting motor (M1); a controller (130), which is configured to estimate a rotational moment of inertia of the cutting motor (M1), and control the operation of the cutting motor (M1) according to the rotational moment of inertia of the cutting motor (M1). The tool can realize fault detection of the cutting blade and control the operation of the cutting motor by means of the rotational moment of inertia of the cutting motor, thereby improving the reliability of fault detection and control of the cutting blade.

Description

Electric lawn mowers and power tools

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on October 30, 2023, with application number 202311428602.2, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the technical field of fault detection of electric tools, and in particular to an electric lawn mower and an electric tool. Background Art

[0003] Power tools are widely used in the tool industry due to their high practicality. Some power tools often require a rotating component to perform their functions, such as the cutting assembly in a lawn mower or the motor fan. Failure of the cutting assembly or the motor fan can severely impact the power tool's performance.

[0004] This section provides background information related to the present application which is not necessarily prior art.

[0005] Summary of the Invention

[0006] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide an electric lawn mower and an electric tool to achieve high-reliability fault detection of the electric tool rotating assembly.

[0007] According to one aspect of the present application, an electric lawn mower is provided, comprising: a cutting assembly including a cutting blade and a cutting motor for driving the cutting blade to perform a cutting action; a power supply device including at least one battery pack for supplying power to the cutting motor; and a controller, the controller being configured to determine whether the cutting blade is faulty based on the rotational inertia of the cutting motor, and to control the cutting motor to stop or reduce its speed when it is determined that the cutting blade is faulty.

[0008] In some embodiments, the controller includes a rotational inertia estimation module configured to estimate the rotational inertia based on mechanical data of the cutting motor.

[0009] In some embodiments, the mechanical data of the cutting motor includes at least the output torque and the rotational speed of the cutting motor.

[0010] In some embodiments, the controller controls the operation of the cutting motor by vector control to achieve the function of a lawn mower.

[0011] In some embodiments, the controller is configured to estimate the moment of inertia of the cutting motor by a model reference adaptive method, and control the operation of the cutting motor based on the moment of inertia.

[0012] In some embodiments, the controller is configured to estimate the moment of inertia of the cutting motor by a recursive least squares identification method, and control the operation of the cutting motor based on the moment of inertia.

[0013] In some embodiments, the controller is configured to estimate the moment of inertia of the cutting motor by a Kalman predictor and control the operation of the cutting motor based on the moment of inertia.

[0014] In some embodiments, the controller is configured to determine that the cutting blade has failed when the moment of inertia satisfies a preset failure condition.

[0015] In some embodiments, the controller determines that the cutting blade has failed after the moment of inertia exceeds a preset range.

[0016] In some embodiments, the cutting blade failure includes at least a missing blade or a damaged blade.

[0017] In some embodiments, the cutting motor comprises a three-phase brushless motor.

[0018] In some embodiments, the electric lawn mower includes at least one of a push lawn mower, a manned lawn mower, and an intelligent lawn mower.

[0019] According to another aspect of the present application, there is provided an electric lawn mower comprising: a drive motor including an output shaft;

[0020] A rotating device is provided on the output shaft and driven to rotate by the output shaft; and a controller is configured to estimate the rotational inertia of the drive motor, estimate the state change of the rotating device according to the change of the rotational inertia, and thereby control the operation of the drive motor.

[0021] In some embodiments, the controller controls the operation of the drive motor by vector control to realize the functions of the power tool.

[0022] In some embodiments, the controller is configured to estimate the moment of inertia of the drive motor by a model reference adaptive method.

[0023] In some embodiments, the controller is configured to estimate the moment of inertia of the drive motor by a recursive least squares identification method.

[0024] In some embodiments, the controller is configured to determine whether the rotating device is faulty based on the moment of inertia, and control the drive motor to stop running when it is determined that the rotating device is faulty.

[0025] In some embodiments, the rotating device comprises a fan or a cutting blade.

[0026] According to another aspect of the present application, an electric tool includes: a drive motor including an output shaft; a rotating device, which is arranged on the output shaft and driven to rotate by the output shaft; and a controller, which is configured to estimate the rotational inertia of the drive motor, and estimate the state change of the rotating device based on the change in the rotational inertia, thereby controlling the operation of the drive motor.

[0027] In some embodiments, the controller controls the operation of the drive motor by vector control to realize the functions of the power tool.

[0028] In some embodiments, the controller is configured to estimate the moment of inertia of the drive motor by a model reference adaptive method.

[0029] In some embodiments, the controller is configured to estimate the moment of inertia of the drive motor by a recursive least squares identification method.

[0030] In some embodiments, the controller is configured to determine whether the rotating device is faulty based on the moment of inertia, and control the drive motor to stop running when it is determined that the rotating device is faulty.

[0031] In some embodiments, the rotating device comprises a fan or a cutting blade. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] FIG1 is a structural diagram of a lawn mower provided in an embodiment of the present application;

[0033] FIG2 is a structural diagram of a lawn mower provided in an embodiment of the present application;

[0034] FIG3 is a schematic structural diagram of another cutting assembly provided in an embodiment of the present application;

[0035] FIG4 is a schematic diagram of an electric control principle of a driving system of a cutting motor provided in an embodiment of the present application;

[0036] FIG5 is a schematic diagram of an electric control principle of another cutting motor drive system provided in an embodiment of the present application;

[0037] FIG6 is a schematic diagram of an electric control principle of a driving system of another cutting motor provided in an embodiment of the present application;

[0038] FIG7 is a schematic structural diagram of an electric tool provided in an embodiment of the present application;

[0039] FIG8 is a schematic structural diagram of another electric tool provided in an embodiment of the present application;

[0040] FIG9 is a schematic structural diagram of a drive system of a drive motor provided in an embodiment of the present application;

[0041] FIG10 is a schematic diagram of an electronic control system of another drive motor provided in an embodiment of the present application;

[0042] FIG11 is a schematic diagram of an electronic control system for a drive motor according to another embodiment of the present application;

[0043] FIG12 is a graph showing a model for estimating the moment of inertia using the least squares method provided in an embodiment of the present application;

[0044] FIG13 is a model curve diagram of estimating the moment of inertia using the model reference adaptive method provided in an embodiment of the present application. DETAILED DESCRIPTION

[0045] Before any embodiments of the present 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 foregoing drawings.

[0046] In this application, the terms "comprises," "includes," "has," or any other variations thereof are intended to encompass non-exclusive inclusion, such that a process, method, article, or apparatus that includes a list of elements includes not only those elements but also other elements not explicitly listed, or elements inherent to such process, method, article, or apparatus. In the absence of further limitations, an element defined by the phrase "comprising a ..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

[0047] In this application, the term "and / or" describes a relationship between related objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, or B exists alone. Additionally, the character " / " in this application generally indicates that the related objects are in an "and / or" relationship.

[0048] In this application, the terms "connect," "combine," "couple," and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, a direct connection refers to two parts or components being connected together without an intermediary, and an indirect connection refers to two parts or components being connected to at least one intermediary, with the two parts or components being connected via the intermediary. Furthermore, "connect" and "couple" are not limited to physical or mechanical connections or couplings and may include electrical connections or couplings.

[0049] In this application, it will be understood by those skilled in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerance caused by manufacturing, assembly, use, etc. associated with a specific value. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0050] In this application, it will be understood by those skilled in the art that the function performed by an assembly can be performed by one assembly, multiple assemblies, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one assembly, or a combination of multiple parts.

[0051] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to the other element "upper" or "lower", but also be indirectly connected to the other element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, below can include directly below, lower left, lower right, lower front and lower back, etc.

[0052] In this application, the terms "controller," "processor," "central processing unit," "CPU," and "MCU" are used interchangeably. Where a unit "controller," "processor," "central processing unit," "CPU," or "MCU" is used to perform a particular function, unless otherwise specified, the function may be performed by a single unit or multiple units.

[0053] In this application, the terms "device", "module" or "unit" can be implemented in the form of hardware or software to achieve specific functions.

[0054] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0055] Figure 1 is a schematic diagram of the structure of an electric lawn mower provided in an embodiment of the present application, specifically a push-type lawn mower. Figure 3 is a schematic diagram of the structure of another electric lawn mower provided in an embodiment of the present application, specifically a smart lawn mower. The electric lawn mower in the present application also includes a manned lawn mower. Figure 2 is a schematic diagram of the structure of a cutting assembly provided in an embodiment of the present application. Figure 4 is a schematic diagram of the electronic control principle of a drive system of a cutting motor provided in an embodiment of the present application. Referring to Figure 1, the electric lawn mower 100 includes: a walking assembly 110, a cutting assembly 120, and a power supply device 170. Among them, the walking assembly 110 includes a walking wheel 111 and a walking motor (not shown in the figure) that drives the walking wheel to walk. The cutting assembly 120 includes a cutting disc (not shown in the figure), at least one cutting blade 122 provided on the cutting disc, and a cutting motor M1 that drives the cutting blade 122 to perform a cutting action. The power supply device 170 is used to at least supply power to the walking motor and the cutting motor M1. In some embodiments, the power supply device 170 includes a battery pack. As shown in Figure 3 , an electric lawn mower 100a includes a travel assembly 110a having travel wheels 111a, a cutting assembly, and a power supply 170a. As shown in Figure 4 , the electric lawn mower also includes a controller 130 configured to estimate the moment of inertia of the cutting motor M1 and control the operation of the cutting motor M1 based on the moment of inertia.

[0056] Specifically, the travel motor can drive the travel wheel 111 to rotate, so that the electric lawn mower 100 can move. The cutting disc is connected to the output shaft of the cutting motor M1, so that the cutting disc can rotate under the drive of the cutting motor M1. The cutting blade 122 is fixedly set on the cutting disc, so that the multiple cutting blades 122 on the cutting disc can perform cutting actions. The cutting disc is a circular thin sheet. In some embodiments, multiple cutting blades, such as 3, 4 or 5, etc., can be fixedly set on a cutting disc, and the embodiments of the present application do not make specific limitations on this. It can be understood that the cutting blades 122 are evenly distributed on the cutting disc. For example, if the number of cutting blades 122 is an odd number, then along a circle with the same distance from the center of the cutting disc, the cutting blades 122 are spaced at the same distance to achieve uniform distribution of the cutting blades 122 on the cutting disc. If the number of the cutting blades 122 is an even number, the cutting blades 122 are distributed symmetrically around the center of the cutting disc, so as to achieve uniform distribution of the cutting blades 122 on the cutting disc.

[0057] During mowing with the electric lawn mower 100, the even distribution of multiple cutting blades 122 on the cutting disc allows the disc to rotate smoothly under the drive of the cutting motor M1, resulting in a good mowing effect. However, if one or more cutting blades 122 on the cutting disc malfunction, such as being missing or damaged, the even distribution of the cutting blades on the cutting disc may be disrupted. For example, if the even distribution of positions or mass is disrupted, the unbalanced rotation may cause the electric lawn mower 100 to vibrate significantly, thereby affecting the mowing effect.

[0058] In some embodiments, the cutting motor M1 can be an electric motor, specifically a three-phase brushless motor, comprising a rotor with permanent magnets and three-phase stator windings U, V, and W with electronic commutation. In some embodiments, the three-phase stator windings U, V, and W are connected in a star configuration. In other embodiments, the three-phase stator windings U, V, and W are connected in a delta configuration. Of course, other types of brushless motors are also within the scope of this disclosure. The moment of inertia of the cutting motor M1 can be understood as the moment of inertia of the motor. When one or more cutting blades 122 on the cutting disc malfunction, the cutting disc begins to rotate unbalancedly, causing its moment of inertia to change, such as experiencing significant vibration, which in turn causes the moment of inertia of the cutting motor M1 to also fluctuate significantly. Therefore, during operation of the electric lawn mower 100, the controller 130 can acquire mechanical data of the cutting motor M1 in real time to estimate the moment of inertia of the cutting motor M1 based on the mechanical data. Furthermore, the controller 130 can determine whether a cutting blade is faulty based on the moment of inertia and control the operation of the cutting motor based on the change in the moment of inertia.

[0059] When the moment of inertia of the cutting motor M1 is abnormal, the controller 130 can determine that the cutting blade 122 is faulty, that is, the cutting blade 122 is missing or damaged. At this time, the cutting motor M1 can be controlled to stop or slow down, so that the cutting blade 122 stops or slows down to perform the cutting work. When the moment of inertia of the cutting motor M1 is not abnormal, it can be determined that the cutting blades 122 are not faulty, and the controller 130 can continue to control the operation of the cutting motor M1 so that the cutting blades 122 perform the mowing work. Specifically, the controller determines that the cutting blade is faulty after the moment of inertia exceeds a preset range. When the cutting blade 122 is not faulty, the estimated moment of inertia is within a certain numerical range. When the moment of inertia is not within the numerical range, it can be determined that the moment of inertia at this time meets the preset fault condition, and then it can be determined that the cutting blade 122 is faulty.

[0060] The electric lawn mower provided in the embodiments of the present application estimates the rotational inertia of the cutting motor in real time when the cutting motor drives the cutting blade to perform the cutting action, so as to determine whether the cutting blade is missing or damaged based on the rotational inertia of the cutting motor. Therefore, when it is determined that the cutting blade is missing or damaged, the cutting motor can be promptly controlled to stop running, and the cutting blade fault detection can be realized through the rotational inertia of the cutting motor, thereby improving the reliability of the cutting blade fault detection.

[0061] Referring to Figure 4, the driving system of the cutting motor may include a controller 130, a power supply device 170, a driving circuit 150 for driving the cutting motor M1, and a parameter detection module 160. The driving circuit 150 includes a plurality of electronic switches (Q1, Q2, Q3, Q4, Q5, Q6) electrically connected between the power supply device 170 and the cutting motor M1, and the control end of each electronic switch is electrically connected to the controller 130. The power supply device 170 provides a power signal to the controller 130 and the driving circuit 150 to realize the power supply function. The driving circuit 150 can output a driving signal to the cutting motor M1 based on the power signal and the PWM signal provided by the controller 130 to drive the cutting motor M1 to operate. The parameter detection module 160 is used to obtain operating data (including operating current, operating voltage, torque or speed, etc.) of the driving cutting motor M1, and transmit the obtained operating data to the controller 130 so that the controller can output a PWM signal to the driving circuit based on the actual operating data of the motor and the user's target operating data.

[0062] Optionally, the controller 130 can control the operation of the cutting motor M1 by vector control to realize the functions of the electric lawn mower 100. Specifically, Figure 5 is a structural diagram of another driving system of a cutting motor provided in an embodiment of the present application. As shown in Figure 5, a vector control system can be integrated into the controller 130. The vector control system can include at least a current loop circuit, a speed loop circuit, and of course a position loop circuit. The above three closed-loop control circuits are the basic circuits that constitute the FOC control circuit. This embodiment does not provide a detailed introduction to the FOC control circuit. In simple terms, the current loop circuit includes two loops, the quadrature axis (i.e., the q-axis) and the direct axis (d-axis). Each loop has two input parameters, one of which is a pre-set current parameter iq * and id * , and the other is the current parameters iq and id of the cutting motor M1 collected by the parameter detection module 160. The speed loop circuit can affect the input parameters of the current loop circuit. In other words, the speed loop circuit adds a PI loop (i.e., speed PI controller 131) in front of the current loop circuit to obtain an input parameter iq in the current loop circuit according to the preset speed parameter and the actual speed parameter of the motor. * and id *. Thus, the current loop circuit and the speed loop circuit can form a speed-current dual closed-loop control. In fact, as shown in FIG5 , the controller 130 also includes a signal processing module 132, in which the speed and position estimation module 1321, the Clark transformation module 1322 and the Park transformation module 1323 are integrated. The position estimation module 1321 can estimate or directly detect the speed or rotor position of the cutting motor M1, and the sampling resistor (not shown) can directly collect the phase current of the cutting motor M1. The collected phase current is subjected to Clark transformation and Park transformation by the Clark transformation module 1322 and the Park transformation module 1323 in turn to obtain the current parameters iq and id. The q-axis PI controller 133 is based on the current parameters iq and iq * Output q-axis voltage uq * , the d-axis PI controller 134 is based on id and id * Output d-axis voltage ud * , Park inverse transformation module 135 is based on the q-axis voltage uq * and d-axis voltage ud * Output intermediate control quantity uα * and uβ * , so that the SVPWM module 136 can be based on the intermediate control amount uα * and uβ * Output the corresponding PWM signal.

[0063] Based on the above embodiment, the controller 130 may be configured with a moment of inertia estimation module to estimate the moment of inertia of the cutting motor M1 based on its mechanical data. The present embodiment does not specifically limit the method for estimating the moment of inertia; exemplary methods may include recursive least squares identification, model reference adaptive method, and extended Kalman filter.

[0064] Optionally, referring to FIG5 , the controller 130 is configured to estimate the moment of inertia of the cutting motor by a recursive least squares identification method.

[0065] For example, the controller 130 may include a first moment of inertia estimation module 137 , which can estimate the moment of inertia of the cutting motor by using a recursive least squares identification method.

[0066] Specifically, when estimating the moment of inertia, the first moment of inertia estimation module 137 may first obtain the recursive formula of the least square method: in, y is the output, φ is the input, θ is a constant, K matrix is ​​the gain matrix, I is the identity matrix, and λ is the forgetting factor. The value range of λ can be [0.95, 1], which can reduce the influence of old data during the iteration process.

[0067] Then, the mechanical motion equation for driving the cutting motor M1 (motor) can be obtained: Where, J is the moment of inertia of the motor load (cutting disc and cutting blade 122), B m is the wind load friction coefficient of the motor, T e is the motor output torque, T L is the load torque, ω m is the actual speed of the motor. During the simulation, the wind load friction coefficient B can be set m is 0, the mechanical motion equation can be simplified to Denote it as formula (1). Discretizing formula (1) yields formula (2): Ignore the load torque T L The change of , we can get formula (3): We can further obtain the discretization equation at (k-2) time: Denote it as formula (4), and subtract formula (3) from formula (4) to obtain: Thus we can determine: y(k) = -2ω m (k-1)+ω m (k-2)+ω m (k), Through the actual motor speed ω m , motor output torque T e , the corresponding moment of inertia J can be determined to estimate the moment of inertia.

[0068] Optionally, the controller 130 is configured to estimate the moment of inertia of the cutting motor using a model reference adaptive method. FIG6 is a schematic diagram of the structure of another cutting motor drive system provided in an embodiment of the present application. As shown in FIG6 , the controller 130 may include a second moment of inertia estimation module 138, which estimates the moment of inertia of the cutting motor M1 using a model reference adaptive method.

[0069] Specifically, the second moment of inertia estimation module 138 may estimate the moment of inertia according to the mechanical motion equation of the motor: The discretization equation for determining the k-th moment is: The discretization equation at time k-1 is: According to the above two discretization equations, the reference model is determined as: m (k)=2*ω m (k-1)-ω m (k-2)+b*ΔT e (k-1), the adaptive model is Among them, ω m (k) is the actual speed of the motor, is the estimated value of the motor speed, (parameters to be identified), ΔT e (k-1)=T e (k-1)-T e (k-2). Thus, the deviation between the reference model and the adaptive model is According to the discrete-time iterative parameter identification mechanism proposed by Landau, an adaptive algorithm can be designed: In this way, according to the output torque T of the motor at each moment e and speed ω m , the moment of inertia b can be determined and the estimation of the moment of inertia can be realized.

[0070] Based on the same concept, an embodiment of the present application also provides an electric tool. Figure 7 is a structural schematic diagram of an electric tool provided by an embodiment of the present application, Figure 8 is a structural schematic diagram of another electric tool provided by an embodiment of the present application, and Figure 9 is a structural schematic diagram of a drive system of a drive motor provided by an embodiment of the present application. With reference to Figures 7, 8 and 9, the electric tool 200 includes a drive motor M2, including an output shaft 211; a rotating device 220, which is arranged on the output shaft 211 and driven to rotate by the output shaft 211; and a controller 230, which is configured to estimate the rotational inertia of the drive motor M2, and obtain the state change of the rotating device 220 according to the change in the rotational inertia.

[0071] Specifically, the power tool 200 may be a screwdriver, electric drill, wrench, angle grinder, or other power tool that requires speed regulation; a sander or other power tool that may be used to grind a workpiece; a reciprocating saw, circular saw, jigsaw, or other power tool that may be used to cut a workpiece; or an electric hammer or other power tool that may be used for impact. These tools may also be garden tools, such as pruners, chainsaws, and vehicle-mounted lawn mowers; in addition, these tools may also be used for other purposes, such as blenders. As long as these power tools can adopt the substantive content of the technical solutions disclosed below, they fall within the scope of protection of this application. The embodiments of this application are only illustrative of the power tool 200 as an electric drill.

[0072] As shown in Figure 7, the power tool 200 includes a housing 270, a motor 230, and a power supply 240. The drive motor M2 is disposed within the housing 270. The housing 270 forms a housing for the drive motor M2, the transmission mechanism, and other electronic components such as circuit boards. It constitutes the main body of the power tool 200 and may also include a grip 271 for the user to hold. The drive motor M2 converts electrical energy into power that is transmitted to the functional component 280, which can be mounted at the front end of the housing 270.

[0073] The rotating device 220 can be a motor fan, which is driven to rotate by the drive motor M2 and is used to dissipate heat for the drive motor M2. Therefore, the rotating device 220 can also be regarded as a load of the drive motor M2. Among them, the drive motor M2 can be a three-phase brushless motor, including a rotor with permanent magnets and three-phase stator windings U, V, and W that are electronically commutated. In some embodiments, the three-phase stator windings U, V, and W are star-connected, and in other embodiments, the three-phase stator windings U, V, and W are delta-connected. However, it must be understood that other types of brushless motors are also within the scope of this disclosure.

[0074] It is understandable that when the rotating device 220 is a motor fan, the fan blades are circular and evenly distributed, that is, the central angles between adjacent blades are the same. During the operation of the drive motor M2, the motor fan can be driven to rotate smoothly to achieve good heat dissipation. However, if one or more blades on the motor fan fail, such as being missing or damaged, the balance of the blades will be destroyed, including the destruction of the evenly distributed positions or the destruction of the evenly distributed masses. At this time, when the motor fan rotates, its moment of inertia changes due to the unbalanced rotation, which will affect the heat dissipation effect and indirectly affect the moment of inertia of the drive motor M2.

[0075] Based on this, the controller 230 can acquire the mechanical data of the drive motor M2 in real time while the drive motor M2 is operating, thereby estimating the moment of inertia of the drive motor M2 based on the mechanical data. Furthermore, the controller 230 can determine whether the rotating device 220 is faulty based on the moment of inertia and control the operation of the drive motor M2 based on changes in the moment of inertia.

[0076] For example, if the moment of inertia of the drive motor M2 is abnormal, the controller 230 may determine that the rotating device 220 has failed, i.e., that the fan blades of the motor fan are missing or damaged. In this case, the drive motor M2 may be controlled to stop running, causing the rotating device 220 to stop rotating to dissipate heat. If the moment of inertia of the drive motor M2 is not abnormal, it can be determined that the rotating device 220 has not failed. The controller 230 may continue to control the drive motor M2 to operate, causing the rotating device 220 to continue rotating to dissipate heat.

[0077] The controller determines that the cutting blade has failed when the moment of inertia exceeds a preset range. When the rotating device 220 is not faulty, the estimated moment of inertia should be within a certain range. If the moment of inertia is not within this range, it can be determined that the moment of inertia meets the preset fault condition, and thus the rotating device 220 is faulty.

[0078] The electric tool provided in the embodiment of the present application estimates the rotational inertia of the cutting motor in real time when the cutting motor drives the cutting blade to perform the cutting action, so as to detect whether the cutting blade is missing or damaged based on the rotational inertia of the cutting motor. Therefore, when it is determined that the cutting blade is missing or damaged, the cutting motor can be controlled to stop running in time, and the cutting blade fault detection can be realized through the rotational inertia of the cutting motor, thereby improving the reliability of the cutting blade fault detection.

[0079] Exemplarily, the driving mode of the drive motor M2 can be the same as the driving mode of the cutting motor M1 in the above-mentioned embodiment, that is, the controller 230 can control the operation of the drive motor M1 by vector control to realize the function of the power tool. Figure 10 is a structural schematic diagram of a drive system of another drive motor provided in an embodiment of the present application. In combination with Figures 9 and 10, its drive system can be the same as the drive system structure of the cutting motor M1, including a controller 230, a power supply device 240, a drive circuit 250 for driving the drive motor M2, and a parameter acquisition module 260. The controller 230 can be integrated with a vector control system, specifically including a speed PI controller 231, a signal processing module 232 (including a speed and position estimation module 2321, a Clark transformation module 2322 and a Park transformation module 2323), a q-axis PI controller 233, a d-axis PI controller 234, a Park inverse transformation module 235 and an SVPWM module 236. The relevant principles can be referred to the description of the cutting motor M1 and will not be repeated here.

[0080] Similarly, based on the above embodiment, the controller 230 may be configured with a moment of inertia estimation module to estimate the moment of inertia of the drive motor M2 based on its mechanical data. The present embodiment does not specifically limit the method for estimating the moment of inertia; exemplary methods may include recursive least squares identification, model reference adaptive method, and extended Kalman filter.

[0081] Optionally, referring to FIG. 10 , the controller 230 is configured to estimate the moment of inertia of the driving motor M2 by a recursive least squares identification method.

[0082] Exemplarily, the controller 230 may include a first moment of inertia estimation module 237, which can estimate the moment of inertia of the cutting motor using a recursive least squares identification method. The specific estimation principle can be found in the description of estimating the moment of inertia of the cutting motor M1 using the recursive least squares identification method in the above embodiment, and will not be repeated here.

[0083] Optionally, FIG11 is a structural diagram of a drive system of another drive motor provided in an embodiment of the present application. As shown in FIG11 , the controller 230 is configured to estimate the rotational inertia of the drive motor M2 by a model reference adaptive method.

[0084] Exemplarily, the controller 230 may include a second moment of inertia estimation module 238 that can estimate the moment of inertia of the cutting motor using a model reference adaptive method. The specific estimation principle can be found in the description of estimating the moment of inertia of the cutting motor M1 using the model reference adaptive method in the above embodiment, and will not be repeated here.

[0085] FIG12 is a model curve diagram of the least square method for estimating the moment of inertia provided by the embodiment of the present application, and FIG13 is a model curve diagram of the model reference adaptive method for estimating the moment of inertia provided by the embodiment of the present application. Referring to FIG12 and FIG13, the motor fan is tested, the motor speed is set to 15000 rpm, the gain factor β is 100, and the forgetting factor λ is 0.95. Both the least square method and the model reference adaptive method can achieve fast and accurate identification and tracking. As shown in FIG12 and FIG13, when the motor fan is normal, the estimated moment of inertia of the motor output shaft is 5*10 -6 kg*m 2 At 0.15s, the moment of inertia suddenly changes to 8*10 -6 kg*m 2 As shown in Figure 12, when the motor fan fails, the moment of inertia of the motor output shaft changes significantly. By estimating the moment of inertia of the motor output shaft, fault detection of the cutting blade is performed, improving the reliability of the detection.

[0086] Based on the same concept, an embodiment of the present application further provides a lawn mower comprising: a power supply for at least supplying power to a cutting motor; a cutting assembly comprising a cutting disc, a plurality of cutting blades disposed on the cutting disc, and a cutting motor for driving the cutting blades to perform a cutting action; and a controller configured to estimate the moment of inertia of the cutting motor using a Kalman predictor and control the operation of the cutting motor based on the moment of inertia. The Kalman predictor estimates the moment of inertia of the cutting motor using an extended Kalman filter algorithm.

[0087] The above shows and describes 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 form, and any technical solutions obtained by equivalent replacement or equivalent transformation fall within the scope of protection of this application.

Claims

1. An electric lawn mower, comprising: A cutting assembly, comprising a cutting blade and a cutting motor for driving the cutting blade to perform a cutting action; A power supply device, comprising at least one battery pack, for supplying power to the cutting motor; as well as A controller is configured to determine whether the cutting blade fails according to the rotational inertia of the cutting motor, and control the cutting motor to stop or reduce its speed when it is determined that the cutting blade fails.

2. The electric lawn mower according to claim 1, wherein: The controller includes a moment of inertia estimation module configured to estimate the moment of inertia based on mechanical data of the cutting motor.

3. The electric lawn mower according to claim 2, wherein: The mechanical data of the cutting motor includes at least an output torque and a rotation speed of the cutting motor.

4. The electric lawn mower according to claim 1, wherein: The controller controls the cutting motor to operate in a vector control manner to achieve the function of the lawn mower.

5. The electric lawn mower according to claim 1, wherein: The controller is configured to estimate a moment of inertia of the cutting motor by a model reference adaptive method and control the operation of the cutting motor based on the moment of inertia.

6. The electric lawn mower according to claim 1, wherein: The controller is configured to estimate a moment of inertia of the cutting motor by a recursive least squares identification method and control the operation of the cutting motor based on the moment of inertia.

7. The electric lawn mower according to claim 1, wherein: The controller is configured to estimate a moment of inertia of the cutting motor through a Kalman predictor and control an operation of the cutting motor based on the moment of inertia.

8. The electric lawn mower according to claim 1, wherein: The controller is configured to determine that the cutting blade fails when the moment of inertia satisfies a preset failure condition.

9. The electric lawn mower according to claim 1, wherein: The controller determines that the cutting blade is faulty after the moment of inertia exceeds a preset range.

10. The electric lawn mower according to claim 8, wherein: The cutting blade failure at least includes a missing blade or a damaged blade.

11. The electric lawn mower according to claim 8, wherein: The cutting motor comprises a three-phase brushless motor.

12. The electric lawn mower according to claim 1, wherein: The electric lawn mower includes at least one of a hand-push lawn mower, a manned lawn mower and an intelligent lawn mower.

13. An electric lawn mower comprising: A cutting assembly, comprising a cutting blade and a cutting motor for driving the cutting blade to perform a cutting action; A power supply device, comprising at least one battery pack, for supplying power to the cutting motor; an estimating unit, which estimates the moment of inertia of the cutting motor based on the electrical parameters of the cutting motor; A controller is configured to control the operation of the cutting motor according to the rotational inertia.

14. The electric lawn mower according to claim 13, wherein: The controller is configured to estimate a moment of inertia of the cutting motor through a Kalman predictor and control an operation of the cutting motor based on the moment of inertia.

15. The electric lawn mower according to claim 13, wherein: The controller is configured to determine that the cutting blade fails when the moment of inertia satisfies a preset failure condition.

16. The electric lawn mower according to claim 13, wherein: The controller determines that the cutting blade is faulty after the moment of inertia exceeds a preset range.

17. The electric lawn mower according to claim 15, wherein: The cutting blade failure at least includes a missing blade or a damaged blade.

18. An electric tool comprising: a drive motor including an output shaft; A rotating device, disposed on the output shaft and driven to rotate by the output shaft; as well as The controller is configured to estimate the rotational inertia of the drive motor, and estimate the state change of the rotating device according to the change of the rotational inertia, so as to control the operation of the drive motor.

19. The electric tool according to claim 18, wherein: The controller controls the operation of the driving motor by means of vector control to realize the function of the electric tool.

20. The electric power tool according to claim 18, wherein: The controller is configured to estimate the rotational inertia of the drive motor by a model reference adaptive method.

21. The electric power tool according to claim 18, wherein: The controller is configured to estimate the rotational inertia of the drive motor by a recursive least squares identification method.

22. The electric power tool according to claim 19, wherein: The controller is configured to determine whether the rotating device fails according to the rotational inertia, and control the driving motor to stop running when it is determined that the rotating device fails.

23. The electric power tool according to claim 18, wherein: The rotating device comprises a fan or a cutting blade.

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