chain saw

Abstract

The application discloses a chain saw. The chain saw comprises a housing, a motor supported by the housing, a chain driven by the motor to perform cutting, a guide plate supporting and guiding the chain, and a control circuit comprising a controller and an inverter circuit with a plurality of switching elements, the controller being configured to switch on / off states of the switching elements in the inverter circuit to control operation of the motor; the controller outputs a brake control signal in response to a brake instruction to control a state of the inverter circuit, so that the chain is reduced from a running chain speed to a brake chain speed, and a maximum value of the running chain speed is greater than or equal to 16 m / s, and the brake chain speed is less than or equal to 1 m / s.

Description

Technical Field

[0001] This application relates to the field of power tool technology, for example, to a chainsaw. Background Technology

[0002] A chainsaw is a common handheld garden tool, widely used as private and public green spaces expand. Currently, most chainsaws are electrically powered; the motor inside drives the chain to rotate around a guide plate, causing the L-shaped blades on the chain to cut wood or shrub branches. To ensure user safety and a good user experience, a well-designed braking system is crucial for chainsaws.

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

[0004] One objective of this application is to solve or at least alleviate some or all of the aforementioned problems. To this end, this application provides a chainsaw. To achieve the above objective, this application adopts the following technical solution:

[0005] A chainsaw includes: a housing; a motor supported by the housing; a chain driven by the motor to perform cutting; a guide plate for supporting and guiding the chain; and a control circuit including a controller and an inverter circuit having multiple switching elements, the controller being configured to switch the conduction states of the switching elements in the inverter circuit to control the operation of the motor; the controller outputting a braking control signal in response to a braking command to control the state of the inverter circuit, thereby reducing the chain speed from the running chain speed to the braking chain speed, wherein the maximum value of the running chain speed is greater than or equal to 16 m / s and the braking chain speed is less than or equal to 1 m / s.

[0006] In some embodiments, the maximum running chain speed is greater than or equal to 20 m / s.

[0007] In some embodiments, the braking duration of the chainsaw is less than or equal to 120 ms.

[0008] In some embodiments, the system further includes at least a battery pack that powers the motor, wherein the maximum value of the motor bus voltage during chainsaw braking does not exceed 1.65 times the rated voltage of the battery pack, and / or, the maximum value of the motor bus voltage during chainsaw braking does not exceed 1.5 times the nominal voltage of the battery pack.

[0009] In some embodiments, the system further includes at least a battery pack that powers the motor, wherein the maximum value of the motor bus voltage during chainsaw braking does not exceed 1.4 times the rated voltage of the battery pack, and / or, the maximum value of the motor bus voltage during chainsaw braking does not exceed 1.3 times the nominal voltage of the battery pack.

[0010] In some embodiments, the chainsaw does not have a mechanical braking mechanism.

[0011] In some embodiments, braking commands include user operation commands and self-test anomaly commands.

[0012] In some embodiments, the motor is a brushless motor, and the controller uses the FOC method to control the state of the inverter circuit.

[0013] In some embodiments, the control circuit further includes a parameter detection module configured to detect the operating parameters of the motor; the controller responds to the braking command by performing closed-loop negative feedback regulation of the motor bus voltage based on the current operating parameters of the motor.

[0014] In some embodiments, the controller satisfies one or more of the following boundary conditions during the closed-loop negative feedback regulation of the motor bus voltage: the target value of the bus voltage does not exceed the maximum bus voltage allowed by the battery pack and / or motor hardware; the current actual value of the bus voltage does not exceed the maximum bus voltage allowed by the battery pack and / or motor hardware; and the target value of the bus voltage is greater than or equal to the current actual value of the bus voltage.

[0015] In some embodiments, the controller uses at least an inner current loop and an outer speed loop during normal operation of the motor in the FOC mode, and at least an inner current loop and an outer voltage loop during braking of the motor in the FOC mode.

[0016] In some embodiments, the controller satisfies one or more of the following boundary conditions during the closed-loop negative feedback regulation of the motor current: the target values ​​of the bus current and / or three-phase current do not exceed the maximum current allowed by the battery pack and / or motor hardware; the maximum output power does not exceed the maximum power allowed by at least one of the hardware components of the battery pack, motor, and chainsaw.

[0017] In some embodiments, during motor braking controlled by the controller using the FOC method, the quadrature axis target current is set to a negative value relative to the quadrature axis actual current, and / or the direct axis target current is set to a negative value relative to the direct axis actual current.

[0018] In some embodiments, a large capacitor or backup power source for regenerative braking energy recovery is also included.

[0019] A chainsaw includes: a housing; a motor supported by the housing; a chain driven by the motor to perform cutting; a guide plate for supporting and guiding the chain; and a control circuit including a controller and an inverter circuit having multiple switching elements, the controller being configured to switch the conduction state of the switching elements in the inverter circuit to control the operation of the motor; the controller outputting a braking control signal in response to a braking command to control the state of the inverter circuit, thereby braking the chainsaw within 120 ms, and the maximum chain speed of the chain being greater than or equal to 16 m / s.

[0020] A chainsaw includes: a housing; a motor supported by the housing; a battery pack powering at least the motor; a chain driven by the motor to perform cutting; a guide plate supporting and guiding the chain; and a control circuit including a controller and an inverter circuit having multiple switching elements, the controller being configured to switch the conduction states of the switching elements in the inverter circuit to control the operation of the motor; the control circuit outputs a braking control signal in response to a braking command to control the state of the inverter circuit, thereby braking the chainsaw within 120 ms, and the ratio of the maximum value of the motor bus voltage to the rated voltage of the battery pack during braking is less than or equal to 1.65.

[0021] A chainsaw includes: a housing; a motor supported by the housing; a battery pack powering at least the motor; a chain driven by the motor to perform cutting; a guide plate supporting and guiding the chain; and a control circuit including a controller and an inverter circuit having multiple switching elements; the controller is configured to switch the on / off states of the switching elements in the inverter circuit to control the operation of the motor; the control circuit outputs a braking control signal in response to a braking command to control the state of the inverter circuit, thereby braking the chainsaw within 120 ms, and the ratio of the maximum value of the motor bus voltage to the nominal voltage of the battery pack during braking is less than or equal to 1.5.

[0022] A chainsaw includes: a housing; a motor supported by the housing, including a motor shaft and a motor bearing sleeved on the motor shaft; a chain driven by the motor to perform cutting; a guide plate for supporting and guiding the chain; and a distance of less than or equal to 18 mm from the motor bearing on the side closer to the guide plate along the axial direction of the motor shaft to the plane of the guide plate.

[0023] In some embodiments, the minimum distance from the motor bearing to the plane containing the guide plate along the axial direction of the motor shaft is less than or equal to 18 mm.

[0024] In some embodiments, the chainsaw does not have an oil pump, or the oil pump in the oil pump assembly is not located between the guide plate and the motor bearing.

[0025] In some embodiments, the motor shaft directly drives the sprocket.

[0026] In some embodiments, the chainsaw does not have a mechanical braking mechanism.

[0027] In some embodiments, a brake baffle rotatably connected to the housing is also included, the brake baffle having a mass of less than or equal to 70g.

[0028] In some embodiments, a brake baffle rotatably connected to the housing is further included, wherein the distance between the projection of the rotation axis of the brake baffle in a first plane and the projection of the rotation axis of the motor shaft in the first plane is less than or equal to 55 mm, wherein the first plane is perpendicular to the rotation axis of the motor shaft.

[0029] In some embodiments, a brake baffle and a tensioning assembly are further included. The brake baffle is rotatably connected to the housing. The tensioning assembly includes a tensioning operating element that can be operated by a user to adjust the tension of the chain on the outer periphery of the guide plate. A vertical coordinate axis is defined with the center line of the guide plate as the horizontal coordinate axis and the projection of the rotation axis of the brake baffle onto the plane where the guide plate is located. The tensioning operating element is located in the second quadrant of the coordinate system formed by the horizontal coordinate axis and the vertical coordinate axis.

[0030] A chainsaw includes: a housing; a motor supported by the housing, including a motor shaft and a motor bearing sleeved on the motor shaft; a chain driven by the motor to perform cutting; a guide plate for supporting and guiding the chain; and a guard rotatably connected to the housing. The chainsaw also includes an oil pump assembly, at least partially disposed on the side of the motor bearing near the guide plate. Along the axial direction of the motor shaft, the distance from the motor bearing near the guide plate to the plane of the guide plate is less than or equal to 30 mm.

[0031] In some embodiments, the oil pump in the oil pump assembly is located between the motor bearing and the guide plate.

[0032] The technical effects of this application include at least making the chainsaw machine or its power unit more compact and lightweight, reducing vibration and noise, and improving working stability, handling, and lifespan. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of a chainsaw as one embodiment of this application;

[0034] Figure 2 This is a plan view of the internal structure of a chain saw after the side cover has been removed, as shown in one embodiment.

[0036] Figure 3A This is a perspective view of a chainsaw mechanical braking mechanism in a related art, as illustrated in an embodiment.

[0037] Figure 3B This is a plan view of the internal structure of a chainsaw with a mechanical braking mechanism after the side cover has been removed, as shown in another embodiment of the related art.

[0038] Figure 4 This is a cross-sectional view of a chainsaw with the oil pump not located between the motor and the guide plate, as shown in one embodiment.

[0039] Figure 5 This is a cross-sectional view of a chainsaw with the oil pump located between the motor and the guide plate, as shown in another embodiment;

[0040] Figure 6This is a plan view of a chainsaw's brake baffle, tensioning operation component, lighting assembly, etc., as shown in one embodiment;

[0041] Figure 7 This is a schematic diagram of the electrical control principle of a chainsaw as an embodiment in this application;

[0042] Figure 8 yes Figure 7 The diagram shows the electrical control principle of the chainsaw controller responding to braking commands to control the chainsaw braking.

[0043] Figure 9 This is a flowchart of a motor braking control method as an embodiment of this application;

[0044] Figure 10A These are test waveforms of the braking duration and bus voltage of the chainsaw in this application;

[0045] Figure 10B This is a test waveform diagram of the braking duration and motor current of the chainsaw in this application;

[0046] Figure 10C This is a test waveform diagram of braking duration and bus voltage under battery pack braking and energy recovery conditions in the chainsaw of this application.

[0047] Figure captions: 100, Chainsaw; 200, Battery Pack; 10, Housing; 11, Main Handlebar; 11a, Side Handlebar; 12, Brake Baffle / Front Handlebar Cover; 13, Lighting Assembly; 14, Side Cover; 21, Guide Plate; 22, Chain; 231, Tensioning Operation Component; 30, Motor; 31, Motor Shaft; 31a, Output Shaft; 32, Motor Bearing; 40, Control Circuit; 41, Controller; 411, Current Loop; 412, Voltage Loop; 413, Speed ​​Loop; 414, Position Loop; 42, Inverter Circuit; 421, Switching Element; 43, Parameter Detection Module; 44, Energy Storage Module; 50, Oil Pump Assembly; 51, Oil Pump; 61, Brake Steel Band; 62, Brake Disc; 63, Spring;

[0048] G. Center of gravity of the brake baffle; P1. Projection of the brake baffle rotation axis onto the guide plate plane / center of brake baffle rotation; P2. Projection of the motor shaft rotation axis onto the guide plate plane; D. Distance from the motor bearing to the plane where the guide plate is located; 201. Center line of the guide plate / horizontal coordinate axis; 202. Straight line perpendicular to the center line of the guide plate and passing through the center of rotation of the brake baffle / vertical coordinate axis; 203. First plane perpendicular to the motor shaft axis / plane where the guide plate is located. Detailed Implementation

[0049] 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] 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 ​​not using 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.).

[0059] The technical solution proposed in this application will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0060] refer to Figures 1 to 6 This illustrates the chainsaw 100 as one embodiment of this application. Figure 2 , Figure 4 The front, back, left, right, up, and down directions of the chainsaw 100 in this application are also defined, and the directional descriptions mentioned in some parts of the description can be referenced here.

[0061] The chainsaw 100 includes a housing 10, a motor 30, a guide plate 21, and a chain 22. The housing 10 forms the main external structure of the chainsaw 100, and its interior contains a storage space. The housing 10 and its internal storage space provide support, fixation, and storage for other components described later. The guide plate 21 is supported by the housing 10 and extends forward from the front end of the housing 10. The chain 22 is the functional component of the chainsaw 100 that actually performs the cutting action. It surrounds the guide plate 21 and is supported and guided by it. During operation, the L-shaped blades on the chain 22 rotate around the guide plate 21 to cut shrubs and other vegetation.

[0062] The motor 30 is the prime mover of the chainsaw 100. It is housed within the housing 10 and converts electrical energy into mechanical energy to rotate the motor shaft 31. This mechanical energy then directly or indirectly drives the output shaft via a transmission assembly, causing the connected chain 22 to rotate and perform cutting. The motor 30 includes a nested stator and rotor. Electromagnetic induction between the stator and rotor enables the energy conversion. The motor 30 also includes a motor shaft 31 and motor bearings 32. The motor shaft 31 is connected to the rotor and rotates with it, while the motor bearings 32 support, limit, and protect them. In some embodiments, the motor 30 is a DC motor; in some embodiments, it is a permanent magnet motor; in some embodiments, it is a brushless motor; and in some embodiments, it is a brushless DC motor. In some embodiments, the motor 30 is a sensorless brushless DC motor; in other embodiments, the motor 30 may also have a position sensor such as a Hall element to detect the rotor's position, thereby assisting in the operation control of the motor 30. In some embodiments, the chainsaw 100 also includes a power supply device such as a battery pack 200 that can be detachably connected to the tool body. The housing 10 typically has a portion for mounting the battery pack 200, which can at least supply power to the motor 30. Of course, components such as the control circuit 40, which will be described later, can also be powered by the battery pack 200.

[0063] Following on from the previous text, to ensure user safety and experience, the design of the braking function in a chainsaw is crucial. Currently, relevant technologies include... Figure 3A and Figure 3B As shown, a chainsaw typically includes a brake operating element such as a brake baffle and a connected mechanical braking mechanism. This mechanical braking mechanism usually includes a brake disc 62 connected to the end of the chainsaw output shaft 31a and a brake band 61 connected to the aforementioned brake operating element 12 (e.g., connected by a spring 63) and located near the outer periphery of the brake disc 62. After the brake baffle 12 is operated, the brake band 61 extends and retracts towards the brake disc 62, contacting / adhering to / enclosing at least a portion of the outer periphery of the brake disc 62, thereby clamping the brake disc 62 and restricting its movement. The brake disc 62 and the chainsaw output shaft 31a are braked by friction or other forces between them. Of course, Figure 3A and Figure 3B The mechanical braking mechanisms shown are just one example, but they all increase the complexity of the chainsaw's internal structure, making the chainsaw larger and heavier, which is detrimental to user safety and experience. For example, the brake belt and brake disc structure will result in a longer motor shaft cantilever and will also increase the chainsaw's vibration.

[0064] To solve the above-mentioned technical problems, the chainsaw 100 in this application, in addition to including the housing 10, guide plate 21, chain 22, and motor 30, also includes a control circuit 40, as shown in the reference. Figures 7 to 8 The control circuit 40 is connected between the battery pack 200 and the motor 30, and includes at least a controller 41 and an inverter circuit 42 having multiple switching elements 421. The controller 41 is configured to switch the conduction states of the switching elements 421 in the inverter circuit 42 to control the operation of the motor 30. Specifically, as... Figure 7 As shown, the inverter circuit 42 is connected between the battery pack 200 and the motor 30, and is also connected to the controller 41. The controller 41 can output different control signals to the inverter circuit 42. The conduction state of one or more switching elements 421 in the inverter circuit 42 will change due to the change of the control signal. The conduction state of the switching elements 421 will correspondingly affect the energy transfer from the battery pack 200 to the motor windings, change the magnetic field of the motor stator and rotor, and thus realize the operation control of the motor 30. In some embodiments, the controller 41 can be an MCU (Microcontroller Unit), ARM (Advanced Reduced Instruction Set Computing Machine), DSP (Digital Signal Processor), etc., which can run relevant programs and output control signals such as pulse-width modulation (PWM) signals to the inverter circuit 42. In some embodiments, the inverter circuit 42 is a three-phase bridge circuit. The controller 41 can output signals to the six switching elements in the three-phase bridge circuit to adjust the magnitude and direction of the current in the motor windings. In some embodiments, the switching element may be a BJT (Bipolar Junction Transistor), or a MOSFET (Metal Oxide Semiconductor Field Effect Transistor), or an IGBT (Insulated Gate Bipolar Transistor).

[0065] In one alternative implementation, the braking function of the chainsaw 100 in this application is achieved by an electronic braking mechanism instead of a mechanical braking mechanism. The controller 41 in the control circuit 40 will output a braking control signal in response to the braking command of the chainsaw 100 to control the state of the inverter circuit 42, thereby reducing the chain speed 22 of the chainsaw 100 from the running chain speed to the braking chain speed. The maximum value of the running chain speed of the chainsaw 100 is greater than or equal to 16 m / s, and the braking chain speed is less than or equal to 1 m / s. Both the running chain speed and the braking chain speed are the speeds at which the chain 22 rotates around the guide plate 21. The running chain speed is the speed of the chain 22 when the chainsaw 100 is working normally before braking is applied. The braking chain speed is the speed at which the chainsaw 100 stops actively reducing speed and passively waits for further reduction after braking is applied. That is, the electronic braking mechanism operates at least until the chain speed drops to the braking chain speed. In some embodiments, the maximum value of the running chain speed of the chainsaw 100 can be further increased to greater than or equal to 20 m / s. This implementation aims to eliminate mechanical brakes in high-speed chainsaws to reduce their size, weight, and cost, and to improve vibration issues at high chain speeds.

[0066] In some embodiments, the braking command of the chainsaw 100 includes either a user operation command or a self-check anomaly command. The user operation command is a braking command issued by the user after operating a braking device such as a brake damper, primarily reflecting the user's subjective intention to brake the chainsaw 100. The self-check anomaly command, on the other hand, is issued by the chainsaw 100 itself after detecting motion-related parameters and / or electrical parameters to determine if there are any abnormalities in its motion and / or electrical states, and then sends this command to the controller 41 upon the occurrence of an abnormality. This primarily involves the chainsaw 100 automatically braking due to an abnormality. For details regarding the chainsaw 100's autonomous detection of abnormalities and automatic braking, please refer to the description in Chinese Patent Application No. 202310803482.3.

[0067] In some embodiments, the control circuit 40, in addition to the controller 41 and the inverter circuit 42, also includes a parameter detection module 43, which is configured to detect the operating parameters of the motor 30. For example, it can detect one or more of the operating parameters of the current motor 30 in real time, including but not limited to current, voltage, torque, power, and rotor position. It should be noted that the parameter detection module 43 can detect the above-mentioned operating parameters either by actual hardware measurement or by software simulation and reconstruction. For example, it can use an ADC sampling circuit to detect current, a Hall position sensor to detect rotor position, or a back EMF observation method to determine rotor position. Furthermore, all operating parameters can be measured or simulated, or partially measured and partially simulated. This application does not impose any explicit restrictions on the relevant content.

[0068] In some embodiments, the control circuit 40 of the chainsaw 100 uses FOC (Field-Oriented Control) or VC (Vector Control) to control the state of the inverter circuit 42. Specifically, the control circuit 40 can set input parameters at various levels based on preset parameters and operating parameters measured by the parameter detection module 43, and regulate the output torque and / or output power and / or speed of the motor 30 by the set input parameters, and can control the braking of the motor 30 in response to braking commands. Figure 8 As shown, the controller 41 can at least perform closed-loop negative feedback regulation of the stator current of the motor 30 based on the operating parameters of the motor 30 measured by the parameter detection module 43, using Clarke transform and inverse transform, and Park transform and inverse transform, thereby making the stator current in the motor 30 tend to and maintain the target value in a dynamic equilibrium manner. The above-mentioned current loop is the basic structure under the FOC mode. In this mode, the parameter detection module 43, such as the current sampling circuit, can measure the actual three-phase currents Iu0, Iv0, and Iw0 of the motor 30. The control circuit 40 can transform them sequentially from the three-phase stationary coordinate system to the two-phase stationary coordinate system to obtain Ia0 and Ib0 through Clarke transform and Park transform, and then transform them to the two-phase rotating coordinate system to obtain the direct-axis actual current Id0 and the quadrature-axis actual current Iq0. Based on preset parameters such as motor resistance, inductance, or other characteristic parameters, the control circuit 40 has now obtained the direct-axis target current Id. ref Cross-axis target current Iq ref Based on the direct-axis actual current Id0, the quadrature-axis actual current Iq0, and the corresponding direct-axis target current Id ref Cross-axis target current Iq ref The difference between the voltages is adjusted using PI (proportional-integral) or PID (proportional-integral-derivative) regulation to determine the expected direct-axis and quadrature-axis voltages Ud1 and Uq1 to be transmitted in the next cycle. Inverse Park and Clarke transformations are then performed to ultimately control the three-phase voltages transmitted to the motor 30 in the next cycle to the corresponding Uu1, Uv1, and Uw1. In some embodiments, the transmission of the corresponding three-phase voltages to the motor 30 can be achieved by a vector modulation unit such as an SVPWM (Space Vector PWM) unit.

[0069] In some embodiments, to achieve rapid braking of the chainsaw and improve energy efficiency, in response to a braking command, the controller 41 switches the conduction state of the switching element 421 in the inverter circuit 42 based on the rotor position and / or speed to provide the motor 30 with a reverse acceleration braking torque, thereby braking the motor 30. During this braking process, current flows from the motor winding side to the battery pack side, and the mechanical energy of the motor during braking can be at least partially converted into electrical energy and stored in the battery pack. It should be noted that the reverse braking torque provided by the control circuit 40 during braking directly affects the acceleration of the motor 30, and thus indirectly affects the speed of the motor 30. That is, it provides a reverse acceleration to make the motor 30 decelerate and brake, rather than directly reversing the direction of rotation. For the same rotor position, the switching element that is turned on during normal operation of the motor is at least partially different from the switching element that is turned on during braking. Furthermore, the above-mentioned action of the controller 41 switching the conduction state of the switching element 421 when braking the chainsaw can be performed multiple times over a continuous period of time, for example, as the rotor position changes dynamically. In some embodiments, when the control circuit 40 employs an FOC (Free-Oriented Control) mode, the quadrature-axis target current Iq used in the current loop responds to the braking command. ref and / or direct-axis target current Id ref The actual cross-axis current Iq0 and / or the actual direct-axis current Id0 can be negative. Compared with the related art scheme that directly executes a three-phase short circuit in response to a braking command, the above embodiment can avoid the energy waste caused by the heat dissipation of large current in the stator winding during braking of high-speed chainsaws. In some embodiments, the control circuit 40 can also alternately use the above-mentioned negative torque braking and three-phase short circuit scheme to balance safety and braking efficiency.

[0070] In some embodiments, the controller 41 responds to the braking command to control the entire braking process of reducing the chain speed to zero for a duration of less than or equal to 120 ms. This braking process, from the moment the braking command is triggered until the chain speed drops to zero, is of great significance for the rapid braking of high-speed chainsaws in related technologies.

[0071] Following the previous text, negative torque braking generates feedback energy to the battery pack during the chainsaw braking process. The higher the chainsaw speed, the faster the braking rate, and the shorter the braking process, the greater the feedback energy power. This also increases the likelihood of voltage overshoot between the battery pack and the motor bus, potentially causing battery pack damage or even fire and explosion. This problem is particularly pronounced when the maximum operating chain speed of the chainsaw 100 in this application exceeds 16 m / s and / or the braking process is less than or equal to 120 ms. Therefore, in one alternative implementation, based on the chainsaw 100's control circuit 40 using FOC (Free-Order Control) to control the motor 30, such as... Figure 8As shown, a motor control scheme is proposed to address the above-mentioned technical difficulties. It will have at least an inner current loop 411 and an outer voltage loop 412. Specifically, the controller 41 can perform closed-loop negative feedback regulation of the bus voltage of the motor 30 based on the current operating parameters of the motor 30 in response to the chainsaw braking command. As described above, the current loop 411 is the basic component of the FOC (Fuel Controller) method. A common technique in related technologies is to add a speed loop 413 outside the current loop 411. The current loop 411 uses the target current and actual current as input parameters and obtains output parameters using PI control or similar methods. These output parameters can regulate or indicate the magnitude and direction of the subsequent three-phase voltage. Similarly, the speed loop 412 outside the current loop 411 uses the target rotational speed and actual rotational speed as input parameters and obtains output parameters using PI control or similar methods. Its output parameters can directly or indirectly obtain the target current input parameter of the subsequent current loop 411. However, the above scheme is not conducive to guiding the intensity of the feedback power during braking control. Therefore, in this embodiment, the voltage loop 412 will replace the speed loop 413 as the FOC during the braking process of the chainsaw 100. In the outer loop, the bus voltage is used as the negative feedback adjustment target. In some embodiments, during the closed-loop negative feedback adjustment of the bus voltage between the battery pack 200 and the motor 30, the controller 41 can satisfy one or more of the following boundary conditions, including but not limited to: the target value of the bus voltage does not exceed the maximum bus voltage allowed by the hardware of the battery pack 200 and / or the motor 30; the current actual value of the bus voltage does not exceed the maximum bus voltage allowed by the hardware of the battery pack 200 and / or the motor 30; the target value of the bus voltage is greater than or equal to the current actual value of the bus voltage, etc.; thereby, the voltage loop 412 continuously and dynamically solves the maximum negative torque current (exemplarily, Iq) that can be used within the safe allowable range of the hardware of each component based on the difference between the current actual value and the target value of the bus voltage. ref =-Kp·ΔUdc-Ki·∫(ΔUdc)dt, ΔUdc=Udc ref -Udc0), and transmits the input parameters to the next-level FOC inner loop current loop 411, so as to avoid bus voltage overshoot while performing rapid braking and reverse charging, thereby reducing the safety risks to the battery pack, motor, and chainsaw. In some embodiments, during the closed-loop negative feedback regulation of braking the chainsaw 100 using the above scheme, the maximum bus voltage allowed by the hardware and the numerical relationship between the target value and the actual value of the bus voltage during regulation are mainly manifested as follows: the target value of the bus voltage is less than the maximum value of the bus voltage but greater than the actual value of the bus voltage. In some embodiments, the quadrature-axis target current Iq output by the voltage loop 412 is... ref It is negative to provide negative torque for braking the rotor; further, in some embodiments, the direct-axis target current Id of the input current loop 411 is... refIt can also be negative to improve the bus voltage rise caused by reverse feedback. In some embodiments, the controller 41 can satisfy one or more of the following boundary conditions during the closed-loop negative feedback regulation of the motor current: the target value of the bus current and / or the three-phase current does not exceed the maximum current allowed by the hardware of the battery pack 200 and / or the motor 30; the maximum output power does not exceed the maximum power allowed by the hardware of at least one of the battery pack 200, the motor 30, and the chainsaw 100. For example, the direct-axis target current Id of the input current loop 411. ref It can be based on the quadrature axis target current Iq ref Determined by calculation of the current limiting circle In some embodiments, the output of the voltage loop 412 is used as an intermediate parameter. The maximum negative torque current calculated by the voltage loop 412 is further adjusted under the constraints of current limit, power limit, and the limitation of braking speed by the no position vector control algorithm before being output to the current loop 411.

[0072] In some embodiments, such as Figure 8 As shown, in the chainsaw 100, when the controller 41 controls the motor 30 to brake using the FOC method, it uses at least a current loop 411 as the inner loop and a voltage loop 412 as the outer loop. However, when controlling the motor 30 to operate normally using the FOC method, it uses at least a current loop 411 as the inner loop and a speed loop 413 as the outer loop. In some embodiments, the controller 41 uses a current loop 411, a speed loop 413, and a position loop 414 when controlling the motor 30 to operate normally using the FOC method.

[0073] Correspondingly, this application also provides a control method for motor braking, see reference. Figure 9 This method uses FOC (Fuel-Oriented Control) to control the motor. Responding to braking commands, the outer loop of the current loop can be switched to a voltage loop, and the output of the voltage loop is used to determine the input parameters of the current loop during braking. Specifically, for example... Figure 9 As shown, in response to the braking command, the following steps are periodically executed during the braking process: The quadrature-axis target current Iq for this cycle is calculated in the voltage loop based on the target bus voltage and the currently acquired actual bus voltage. ref Furthermore, it can also be based on the quadrature-axis target current Iq ref Calculate the direct-axis target current Id for this period. ref and the cross-axis target current Iq ref (or the cross-axis target current Iq) ref and direct-axis target current Id ref The input parameter is passed to the current loop; the current loop is based on the target current Iq of the quadrature and direct axes. ref 、Id refThe three-phase voltage expected to be transferred this week is calculated based on the actual three-phase current of the motor currently collected; this continues until the motor braking is complete. In some embodiments, the voltage loop calculation process satisfies one or more of the following boundary conditions, including but not limited to: the target value of the bus voltage does not exceed the maximum bus voltage allowed by the battery pack and / or motor hardware; the target value of the bus voltage is less than or equal to the current actual value of the bus voltage; the target value of the bus current and / or three-phase current does not exceed the maximum current allowed by the battery pack and / or motor hardware; the maximum output power does not exceed the maximum power allowed by at least one of the following hardware: battery pack, motor, chainsaw.

[0074] The above-mentioned braking process uses a voltage loop to replace the speed loop as the outer loop of the current loop. This scheme can achieve closed-loop negative feedback regulation of the bus voltage between the battery pack and the motor while meeting the requirements of rapid braking with negative torque. The current loop uses the AC and DC axis current values ​​calculated in real time under the voltage loop as the target value. It can continuously and dynamically brake with the maximum negative torque current within the hardware safety allowable range, smoothly achieve chainsaw braking along the numerical boundary, and prevent the bus voltage from overshooting. This ensures the safety of the battery pack, motor, and chainsaw.

[0075] In some embodiments, such as Figure 7 As shown, the control circuit 40 also includes an energy storage module 44, such as a large capacitor and / or a backup power supply, which can be connected in parallel between the battery pack 200 and the inverter circuit 42. This module can collect and store the regenerative braking energy, thereby mitigating its impact on the safety of the battery pack 200. In some embodiments, the battery pack may not participate in energy recovery during chainsaw braking, and the energy storage module 44, in conjunction with the control circuit 40, can be used to achieve this. However, if it is still necessary to maintain the bus voltage within a safe range, then... Figure 10C As shown, the chainsaw braking process may be extended to more than 120ms, so the three-phase short-circuit scheme can be used intermittently to reduce the braking time.

[0076] As mentioned above, the feedback energy generated during chainsaw braking increases with the increase of chainsaw speed and braking rate. Reducing the possibility of voltage overshoot on the bus between the battery pack and the motor is of great significance in related technologies. In some embodiments, when the control circuit 40 controls the chainsaw braking, the ratio of the maximum value of the bus voltage of the motor 30 to the rated voltage of the battery pack 200 during braking is less than or equal to 1.65, and / or, the ratio of the maximum value of the bus voltage of the motor 30 to the nominal voltage of the battery pack 200 is less than or equal to 1.5. Optionally, in some embodiments, the ratio of the maximum value of the bus voltage of the motor 30 to the rated voltage of the battery pack 200 during braking is less than or equal to 1.5, and / or, the ratio of the maximum value of the bus voltage of the motor 30 to the nominal voltage of the battery pack 200 is less than or equal to 1.35. Preferably, in some embodiments, the ratio of the maximum value of the bus voltage of the motor 30 during braking to the rated voltage of the battery pack 200 is less than or equal to 1.4, and / or, the ratio is less than or equal to 1.3. Further, in some embodiments, the ratio of the maximum value of the bus voltage of the motor 30 during braking to the rated voltage of the battery pack 200 is less than or equal to 1.35, and / or, the ratio is less than or equal to 1.25. Figure 10A , Figure 10B As shown, the braking time of the chain saw in this application is approximately 68.5ms, the peak value of the motor bus voltage is 67.4V, the voltage rise value is 10.4V, the braking current is 210A, the battery pack uses 14 series-connected cells, the rated voltage of the cells is 3.6V, the nominal voltage is 4V, the rated voltage of the battery pack is 14*3.6V, i.e., 50.4V, and its nominal voltage is 14*4V, i.e., 56V. Therefore, the ratio of the maximum value of the motor bus voltage to the rated voltage of the battery pack during the chainsaw braking process is 1.337, and the ratio of the maximum value of the motor bus voltage to the nominal voltage of the battery pack is 1.204. The above ratios when the chainsaw is powered by other types of battery packs can also be calculated by referring to the method described above.

[0077] In another alternative implementation, the braking function of the chainsaw 100 is achieved by an electronic braking mechanism instead of a mechanical braking mechanism. The controller 41 in the control circuit 40 responds to the chainsaw braking command by outputting a braking control signal to control the state of the inverter circuit 42, thereby braking the chainsaw within 120 ms. Furthermore, the maximum operating speed of the chainsaw 100 is greater than or equal to 16 m / s. Here, braking the chainsaw within 120 ms means that from the moment the braking command is issued, for example, from the moment the user operates the brake lever to brake, the chain speed of the chainsaw 100 can be reduced from its operating chain speed to zero within 120 ms. In some embodiments, the maximum operating chain speed of the chainsaw 100 can be further increased to greater than or equal to 20 m / s. This embodiment aims to eliminate the mechanical braking mechanism in high-speed chainsaws to reduce their size, weight, and cost, and to improve vibration problems at high speeds.

[0078] It should be noted that, under the above-described embodiments, the chainsaw 100 can brake the motor 30 solely by the response of the controller 41 to the braking command, thereby rapidly reducing the chain speed of the chain 22 from the running chain speed to the braking chain speed. The chainsaw 100 does not have a mechanical braking mechanism, that is, it does not include structures such as the brake disc and brake steel belt mentioned above, thus mitigating the vibration problem of the high-speed chainsaw and optimizing its size and weight.

[0079] Correspondingly, following the preceding text, in one alternative embodiment, the chainsaw 100, in addition to the housing 10, guide plate 21, chain 22, and motor 30, also includes a control circuit 40 with a controller 41 and an inverter circuit 42. The controller 41 switches the conduction state of the switching element 421 in the inverter circuit 42 to control the motor 30 to operate in the intended manner. In response to a braking command, the control circuit 40 outputs a braking control signal to control the state of the inverter circuit 42, thereby braking the motor 30 within 120 ms. During this braking process, the ratio of the maximum value of the motor 30's bus voltage to the rated voltage of the battery pack 200 is less than or equal to 1.65, and / or, the ratio of the maximum value of the motor 30's bus voltage to the nominal voltage of the battery pack 200 is less than or equal to 1.5. Preferably, in some embodiments, the ratio of the maximum value of the bus voltage of the motor 30 to the rated voltage of the battery pack 200 during braking is less than or equal to 1.4, and / or, the ratio of the maximum value of the bus voltage of the motor 30 to the nominal voltage of the battery pack 200 is less than or equal to 1.3. In another alternative embodiment, the maximum operating chain speed of the chainsaw 100 is greater than or equal to 16 m / s. In response to a braking command, the control circuit 40 outputs a braking control signal to control the state of the inverter circuit 42, thereby braking the motor 30. During this braking process, the ratio of the maximum value of the bus voltage of the motor 30 to the rated voltage of the battery pack 200 is less than or equal to 1.65, and / or, the ratio of the maximum value of the bus voltage of the motor 30 to the nominal voltage of the battery pack 200 is less than or equal to 1.5. Preferably, in some embodiments, the ratio of the maximum value of the bus voltage of the motor 30 during braking to the rated voltage of the battery pack 200 is less than or equal to 1.4, and / or the ratio of the maximum value of the bus voltage of the motor 30 to the nominal voltage of the battery pack 200 is less than or equal to 1.3. In this embodiment, the chainsaw 100 may or may not have a mechanical braking mechanism.

[0080] Furthermore, in an alternative implementation, such as Figure 4As shown, the chainsaw 100 includes a housing 10, a guide plate 21, a chain 22, and a motor 30. The motor 30 has a nested stator and rotor, and also includes a motor shaft 31 extending axially at the radial center of the motor 30 and connected to the rotor for rotation around an axis, and one or more motor bearings 32 sleeved on the motor shaft 31 to ensure motor operation stability. At least one of these motor bearings 32 is located near the guide plate side, between the guide plate 21 and the stator and rotor of the motor 30. Through reasonable structural arrangement adjustments and brake mechanism optimization, the distance D between the motor bearing 32 near the guide plate side and the plane containing the guide plate 21 is less than or equal to 18 mm along the axial direction of the motor shaft 31. In some embodiments, preferably, the distance D between the motor bearing 32 near the guide plate side and the plane containing the guide plate 21 can be less than or equal to 12 mm. In another alternative implementation, the minimum distance D between the motor bearing 32 and the plane of the guide plate 21, that is, the distance D between the motor bearing 32 closest to the guide plate 21 and the plane of the guide plate 21, is less than or equal to 18 mm, preferably less than or equal to 12 mm.

[0081] In some embodiments, the chainsaw 100 does not have an oil pump 51 or the oil pump 51 in the oil pump assembly 50 is not located between the guide plate 21 and the motor 30, thereby reducing the width of the chainsaw 100 housing in the left-right direction and making the related structure more compact.

[0082] In some embodiments, the motor 30 in the chainsaw 100 drives the chain 22 in a direct-drive manner, and the motor shaft 31 can directly drive the sprocket to rotate without the need for transmission through other components. This simplifies the relevant structure in the chainsaw, but also poses challenges to the cantilever length of the motor shaft and related vibration issues. In some embodiments, the chainsaw 100 does not have a mechanical braking mechanism; it relies solely on an electronic braking mechanism to brake the chainsaw 100, thereby shortening the relevant dimensions by eliminating the brake belt, brake disc, etc.

[0083] In some embodiments, the chainsaw 100 further includes a brake baffle 12 rotatably connected to the housing 10. The brake baffle 12 serves both as a brake actuator for user operation to brake the chainsaw and as a front handle guard 12 located in front of the main handle 11 and / or side handle 11a of the chainsaw 100. It protects the user's hand holding the main handle 11 from accidental injury by the chain 22. During braking, rotating the brake baffle 12 relative to the housing 10 can trigger the chain 22 to stop. In some embodiments, such as... Figure 2As shown, a first plane perpendicular to the rotor's rotation axis is defined, that is, a first plane perpendicular to the motor shaft axis is defined. The distance R between the projection of the rotation axis of the brake baffle 12 onto this first plane and the projection of the rotation axis of the motor shaft 31 or the rotor onto this first plane is less than or equal to 55 mm. In some embodiments, the distance R between the intersection of the motor shaft 31 axis and the first plane and the intersection of the rotation axis of the brake baffle 12 and the first plane is less than or equal to 55 mm. In some embodiments, the rotation axis of the motor shaft 31 or the rotor is parallel to the rotation axis of the brake baffle 12 and is perpendicular to the first plane. When the distance between the rotation center of the brake baffle 12 and the rotation center of the motor shaft 31 decreases, the distance between the center of gravity of the brake baffle 12 and its rotation center increases, and the rotational inertia of the brake baffle 12 increases, making it easier for users to operate and providing a better experience. In some embodiments, the mass of the brake baffle 12 is less than or equal to 70 g to improve the user's experience when operating the brake operating components and reduce the overall weight of the machine. Adjusting the position of the center of gravity or the rotation center can also maintain or optimize the rotational inertia of the brake baffle 12.

[0084] In some embodiments, the chainsaw 100 further includes a tensioning assembly 23, which can be installed together with the guide plate 21 and the chain 22 between the main housing and the side cover 14. The tensioning assembly 23 includes a tensioning operating element 231 disposed on the housing 10 and operable by the user to adjust the tension of the chain 22 on the outer periphery of the guide plate 21. For example, the tensioning operating element 231 can be a tensioning knob. By rotating the tensioning knob in both directions, the guide plate 21 can be moved back and forth to tighten or loosen the chain 22 on the guide plate 21. The mechanism in the tensioning assembly 23 that actually achieves the tensioning of the chain 22 has various selectable structural compositions, and no specific limitation is made here. In some embodiments, such as Figure 6As shown, a two-dimensional coordinate system (planar coordinate system) is defined in the plane of the guide plate 21. The horizontal axis (x-axis) of this coordinate system is the center line 201 of the guide plate, and the forward direction of the guide plate 21 extending out of the housing 10 is taken as the positive x-axis. Simultaneously, the vertical axis (y-axis) of this coordinate system is determined by drawing a vertical line perpendicular to the center line 201, projected onto the plane of the brake baffle 12 through the rotation axis of the brake baffle 12. The positive y-axis is taken as the area above the main housing relative to the main handle 11. The projection of the tensioning operation member 231 of the tensioning assembly 23 onto the plane of the guide plate 21 will fall into the second quadrant of this coordinate system; that is, the tensioning operation member 231 can be mapped to the negative x-axis and the positive y-axis. In some embodiments, in the front-rear direction, the tensioning operation member 231 is at least partially located behind the brake baffle 12. In some embodiments, a lighting component 13 is additionally installed on the housing 10 of the chainsaw 100. Its projection onto the plane of the guide plate 21 falls within the first quadrant of the aforementioned coordinate system. That is, the lighting component 13, such as the LED beads, on the housing 10 can be mapped to the positive x-axis and positive y-axis. Compared to related technologies where the tension knob is limited to the first quadrant of the coordinate system due to structural constraints, by eliminating the mechanical brake mechanism, the position of the tension knob can be arranged more flexibly to make way for other components.

[0085] In another alternative implementation, such as Figure 5 As shown, the chainsaw 100 includes a housing 10, a guide plate 21, a chain 22, and a motor 30. The motor 30 includes a motor shaft 31, a stator, a rotor, and a motor bearing 32. The chainsaw 100 also includes an oil pump assembly 50, which is at least partially disposed on the side of the motor bearing 32 near the guide plate 21. In some embodiments, the oil pump 51 in the oil pump assembly 50 is disposed between the guide plate 21 and the motor 30, for example, between the guide plate 21 and the motor bearing 32 near the guide plate. Along the axial direction of the motor shaft 31, the distance D between the motor bearing 32 near the guide plate and the plane containing the guide plate 21 is less than or equal to 30 mm. In some embodiments, preferably, the distance D between the motor bearing 32 near the guide plate and the plane containing the guide plate 21 is less than or equal to 24 mm. In another alternative implementation, the minimum distance D between the plane containing the motor bearing 32 and the guide plate 21, i.e., the distance D between the motor bearing 32 closest to the guide plate 21 and the plane containing the guide plate 21, is less than or equal to 30 mm, preferably less than or equal to 24 mm. Compared to the aforementioned implementation, since the oil pump assembly 50 is at least partially disposed between the guide plate 21 and the motor 30, the distance between the motor bearing 32 and the guide plate 21 is affected, and the relevant dimensions are relatively increased, but it still maintains advantages over related technologies.

[0086] It is understood that, provided that the features of the solutions do not conflict, the various embodiments under the multiple implementation methods described above can be cross-combined to comprehensively optimize and improve the chainsaw in this application.

[0087] 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. A chainsaw, comprising: chassis; The motor is supported by the housing; The chain, driven by the motor, performs the cutting. The guide plate supports and guides the chain; A control circuit includes a controller and an inverter circuit having multiple switching elements, the controller being configured to switch the conduction state of the switching elements in the inverter circuit to control the operation of the motor; The controller is characterized in that it outputs a braking control signal in response to a braking command to control the state of the inverter circuit, thereby reducing the chain speed from the running chain speed to the braking chain speed, wherein the maximum value of the running chain speed is greater than or equal to 16 m / s and the braking chain speed is less than or equal to 1 m / s.

2. The chainsaw according to claim 1, characterized in that, The maximum operating chain speed is greater than or equal to 20 m / s, and / or the braking duration of the chainsaw is less than or equal to 120 ms.

3. The chainsaw according to claim 1, characterized in that, It also includes at least a battery pack that powers the motor, wherein the maximum value of the motor’s bus voltage during braking of the chainsaw does not exceed 1.65 times the rated voltage of the battery pack, and / or, the maximum value of the motor’s bus voltage during braking of the chainsaw does not exceed 1.1 times the nominal voltage of the battery pack.

4. The chainsaw according to claim 3, characterized in that, It also includes at least a battery pack that powers the motor, wherein the maximum value of the motor’s bus voltage during braking of the chainsaw does not exceed 1.4 times the rated voltage of the battery pack, and / or, the maximum value of the motor’s bus voltage during braking of the chainsaw does not exceed 1.3 times the nominal voltage of the battery pack.

5. The chainsaw according to claim 1, characterized in that, The chainsaw does not have a mechanical braking mechanism.

6. The chainsaw according to claim 1, characterized in that, The braking commands include user operation commands and self-check anomaly commands.

7. The chainsaw according to claim 1, characterized in that, The motor is a brushless motor, and the controller uses the FOC method to control the state of the inverter circuit. During the braking process of the motor controlled by the controller using the FOC method, the quadrature axis target current is set to a negative value relative to the quadrature axis actual current, and / or the direct axis target current is set to a negative value relative to the direct axis actual current.

8. The chainsaw according to claim 7, characterized in that, The control circuit also includes a parameter detection module configured to detect the operating parameters of the motor; the controller, in response to the braking command, performs closed-loop negative feedback adjustment of the motor's bus voltage based on the motor's current operating parameters.

9. The chainsaw according to claim 8, characterized in that, During the closed-loop negative feedback regulation of the motor's bus voltage by the controller, one or more of the following boundary conditions must be met: the target value of the bus voltage does not exceed the maximum bus voltage allowed by the battery pack and / or motor hardware; the current actual value of the bus voltage does not exceed the maximum bus voltage allowed by the battery pack and / or motor hardware; and the target value of the bus voltage is greater than or equal to the current actual value of the bus voltage.

10. The chainsaw according to claim 7, characterized in that, The controller uses an FOC method to control the motor during normal operation, employing at least an inner current loop and an outer speed loop. Similarly, it uses an FOC method to control the motor during braking, employing at least an inner current loop and an outer voltage loop.

11. A chainsaw, comprising: chassis; The motor is supported by the housing; The chain, driven by the motor, performs the cutting. The guide plate supports and guides the chain; A control circuit includes a controller and an inverter circuit having multiple switching elements, the controller being configured to switch the conduction state of the switching elements in the inverter circuit to control the operation of the motor; The controller is characterized in that it outputs a braking control signal in response to a braking command to control the state of the inverter circuit, thereby braking the chainsaw within 120ms, and the maximum running speed of the chain is greater than or equal to 16m / s.

12. A chainsaw, comprising: chassis; The motor is supported by the housing; The battery pack supplies power to at least the motor; The chain, driven by the motor, performs the cutting. The guide plate supports and guides the chain; A control circuit includes a controller and an inverter circuit having multiple switching elements, the controller being configured to switch the conduction state of the switching elements in the inverter circuit to control the operation of the motor; The control circuit is characterized in that it outputs a braking control signal in response to a braking command to control the state of the inverter circuit, thereby braking the chainsaw within 120ms, and the ratio of the maximum value of the motor bus voltage to the rated voltage of the battery pack during braking is less than or equal to 1.65, and / or the ratio of the maximum value of the motor bus voltage to the nominal voltage of the battery pack during braking is less than or equal to 1.5.

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