Power tool comprising a field-oriented control electronic clutch

Abstract

An electric power tool includes an electric motor, a first sensor configured to monitor an electrical characteristic of the electric motor, and an electronic controller. The electronic controller is configured to determine at least one of a quadrature-axis current and a direct-axis current of the electric motor based on a sensor signal from the first sensor, determine a rotational speed of the electric motor, determine an estimated torque output based on (i) the at least one of the quadrature-axis current and the direct-axis current and (ii) the rotational speed, and output a command to brake the electric motor in response to the estimated torque output crossing a threshold.

Description

[0001] Related applications This application claims the benefit of U.S. Provisional Patent Application No. 63 / 779,412, filed March 28, 2025, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This invention relates to power tools, and more particularly to power tools that utilize magnetic field-oriented control. Summary of the Invention

[0003] Power tools may include torque limiting mechanisms such as clutches, which regulate the torque output from the power tool, for example, by controlling the torque transmitted from the motor to the output shaft. Implementing torque limiting mechanisms in power tools can provide various technical benefits. For example, a torque limiting mechanism can interrupt torque transmission when the torque output reaches or exceeds a predetermined threshold. In some examples, such as when the power tool is implemented as a drill / drive, a torque limiting mechanism can allow the user to apply a specific amount of torque to fasteners. This can help achieve precise tightening and / or prevent overtightening, which could otherwise damage the fasteners or the material being secured.

[0004] Additionally, torque limiting mechanisms can reduce stress on the internal components of power tools. By interrupting torque transmission before excessive force is applied, these mechanisms help reduce wear on gears, bearings, or other load-bearing components. This reduction in mechanical stress can contribute to improving tool durability and lifespan.

[0005] In some examples, the torque limiting mechanism is implemented as a mechanical clutch. A mechanical clutch may include components such as friction plates, springs, or ball-and-pawl mechanisms, configured to disengage or slip when the torque transmitted from the motor to the output shaft reaches or exceeds a predetermined threshold. While mechanical clutches can provide reliable torque limiting functionality, they may also have certain technical limitations. For example, repeated engagement and disengagement of mechanical components over time can lead to wear. Additionally, mechanical clutches may have limited precision in controlling the torque threshold because factors such as friction, spring fatigue, and material properties can introduce variability. Mechanical clutches may also generate noise and vibration during operation, which can negatively impact user experience and tool ergonomics.

[0006] To address these technical challenges, electronic clutches can be implemented in power tools. An electronic clutch can estimate the motor's torque output based on electrical parameters and electronically control the motor to interrupt torque transmission when the estimated torque meets or exceeds a threshold. Compared to mechanical clutches, electronic clutches can provide more precise and consistent torque threshold control because the torque estimation can be dynamically adjusted based on sensor feedback. Furthermore, electronic clutches reduce mechanical wear by eliminating the need for physical engagement parts.

[0007] Despite these advantages, implementing electronic clutches can still be technically challenging. For example, accurately estimating the torque output of a power tool can be complex because the torque at the motor does not necessarily correspond to the torque at the output shaft. Torque losses can occur due to drivetrain inertia, wind resistance, friction, and other parasitic effects. Because these losses can vary under different operating conditions, estimating them in real-time or near real-time can be technically challenging. Furthermore, noise and harmonics in sensor signals can affect the accuracy of torque estimation, and filtering techniques can be used to ensure reliable measurements. However, implementing filtering techniques themselves can be technically challenging. For example, phase delays between filtered signals can introduce errors into torque estimation and control feedback.

[0008] The systems, devices, methods, and techniques described in this invention provide technical solutions to these and other technical problems by implementing torque estimation models that consider various parasitic loss components (such as inertial effects, wind resistance losses, and friction losses) under different operating conditions. For example, since parasitic losses may vary depending on the motor's angular velocity or rotational speed, the torque estimation model can be dynamically adjusted in real-time or near real-time for these variations. By subtracting dynamically estimated (e.g., determined based on electrical parameters) parasitic losses from the estimated motor torque, the system can provide a more accurate estimate of the output torque. Furthermore, filtering techniques can be implemented to synchronize the phase delay between the estimated motor torque and the motor operating conditions, thereby reducing errors in the control feedback.

[0009] Furthermore, in various implementations, the electronic clutch system can provide user feedback to indicate when torque transmission is interrupted. For example, motor jitter, haptic feedback, audible alarms, or visual indicators can be used to enhance ergonomics, usability, and control. Therefore, these and other technologies described in this invention can improve the accuracy, reliability, and overall user experience of electronic clutches in power tools.

[0010] According to some examples, a power tool includes an electric motor, a first sensor configured to monitor the electrical characteristics of the electric motor, and an electronic controller. The electronic controller is configured to determine at least one of the quadrature-axis current and direct-axis current of the electric motor based on sensor signals from the first sensor, determine the rotational speed of the electric motor, determine an estimated torque output based on (i) at least one of the quadrature-axis current and direct-axis current and (ii) the rotational speed, and output a command to brake the electric motor in response to the estimated torque output exceeding a threshold.

[0011] Among other features, the electronic controller is configured to determine the estimated torque output based on a torque estimation model that includes the motor torque component and the parasitic loss component.

[0012] Among other features, the electronic controller is configured to determine the estimated torque output by subtracting the parasitic loss component from the motor torque component.

[0013] Among other features, the electronic controller is configured to determine the estimated motor torque based on a motor torque component, which is a function of at least one of the quadrature-axis current and the direct-axis current.

[0014] Among other features, the electronic controller is further configured to determine the quadrature-axis current and direct-axis current of the electric motor based on sensor signals from the first sensor and to determine an estimated motor torque based on the motor torque components, which are functions of the quadrature-axis current and the direct-axis current.

[0015] Among other features, the electronic controller is configured to determine the estimated parasitic torque loss based on parasitic loss components, where the parasitic loss components are a function of rotational speed.

[0016] Among the other characteristics, the parasitic loss component includes at least one of the inertial component, the wind resistance component, and the friction component.

[0017] Among other features, the electronic controller is further configured to determine the rotational speed of the electric motor based on sensor signals from the first sensor.

[0018] Among other features, the power tool further includes a second sensor configured to monitor the rotational characteristics of the electric motor, and the electronic processor is further configured to determine the rotational speed of the electric motor based on sensor signals from the second sensor.

[0019] Other examples provide a method comprising: determining at least one of a quadrature-axis current and a direct-axis current of an electric motor of a power tool based on a sensor signal from a first sensor configured to monitor the electrical characteristics of the electric motor; determining the rotational speed of the electric motor; determining an estimated torque output based on (i) at least one of the quadrature-axis current and the direct-axis current and (ii) the rotational speed; and outputting a command to brake the electric motor in response to the estimated torque output exceeding a threshold.

[0020] Among other features, the estimated torque output is determined based on a torque estimation model, which includes the motor torque component and the parasitic loss component.

[0021] Among other features, determining the estimated torque output includes subtracting the parasitic loss component from the motor torque component.

[0022] Among other features, the method includes determining an estimated motor torque based on motor torque components, which are functions of at least one of quadrature-axis current and direct-axis current.

[0023] Among other features, the method includes determining the quadrature-axis current and direct-axis current of the electric motor based on sensor signals from a first sensor and determining an estimated motor torque based on motor torque components, which are functions of the quadrature-axis current and direct-axis current.

[0024] Among other features, the method includes determining estimated parasitic torque losses based on parasitic loss components, which are functions of rotational speed.

[0025] Among the other characteristics, the parasitic loss component includes at least one of the inertial component, the wind resistance component, and the friction component.

[0026] Among other features, the rotational speed of the electric motor is determined based on sensor signals from the first sensor.

[0027] Among other features, the rotational speed of the electric motor is determined based on sensor signals from a second sensor configured to monitor the rotational characteristics of the electric motor.

[0028] Other examples provide a non-transitory computer-readable storage medium including executable instructions that, when executed by an electronic processor, cause the electronic processor to: determine at least one of a quadrature-axis current and a direct-axis current of an electric motor of a power tool based on sensor signals from a first sensor configured to monitor the electrical characteristics of the electric motor; determine the rotational speed of the electric motor; determine an estimated torque output based on (i) at least one of the quadrature-axis current and the direct-axis current and (ii) the rotational speed; and output a command to brake the electric motor in response to the estimated torque output exceeding a threshold.

[0029] Among other features, when executed by the electronic processor, executable instructions cause the electronic processor to determine the estimated torque output based on a torque estimation model, which includes the motor torque component and the parasitic loss component.

[0030] Before explaining any implementation in detail, it should be understood that the implementation is not limited in application to the details of the configuration and arrangement of the components described in the following description or shown in the drawings. The implementation can be practiced or implemented in various ways. Furthermore, it should be understood that the wording and terminology used in this invention are for illustrative purposes and should not be considered limiting. The use of “comprising,” “including,” or “having,” and variations thereof is intended to cover the items listed thereafter and their equivalents, as well as additional items. Unless otherwise stated or limited, the terms “mounted,” “connected,” “supported,” and “coupled,” and variations thereof are used broadly and cover direct and indirect mounting, connection, support, and coupling.

[0031] Unless the context of their use explicitly indicates otherwise, the articles “a,” “an,” and “the” should not be interpreted as meaning “one” or “only one.” Rather, these articles should be interpreted as meaning “at least one” or “one or more.” Similarly, when the terms “a” or “said” are used to refer to a noun previously introduced by the indefinite article “a” or “one,” “the” and “said” mean “at least one” or “one or more,” unless the usage explicitly indicates otherwise.

[0032] Furthermore, it should be understood that implementations may include hardware, software, and electronic components or modules, which may be shown and described for the purposes of discussion as if most components were implemented solely in hardware. However, those skilled in the art will recognize from this detailed description that, in at least one implementation, the electronic aspects may be implemented as software (e.g., stored on a non-transitory computer-readable medium) executable by one or more processing units (such as microprocessors and / or application-specific integrated circuits (“ASICs”)). Therefore, it should be noted that various implementations may be implemented using a plurality of hardware and software-based devices and a plurality of different structural components. For example, “server,” “computing device,” “controller,” “processor,” etc., described in the specification may include one or more processing units, one or more computer-readable medium modules, one or more input / output interfaces, and various connections of connection components (e.g., system buses).

[0033] Relative terms used in conjunction with quantities or conditions, such as “about,” “approximately,” “generally,” etc., will be understood by a person skilled in the art to include the value and have a meaning defined by the context (e.g., the term includes at least the degree of error associated with measurement accuracy, the tolerance associated with a particular value [e.g., manufacturing, assembly, use, etc.]). Such terms should also be considered to disclose a range defined by the absolute values ​​of two endpoints. For example, the expression “about 2 to about 4” also discloses a range of “2 to 4.” Relative terms may refer to a percentage added to or subtracted from the indicated value (e.g., 1%, 5%, 10%).

[0034] It should be understood that although some figures illustrate hardware and software within a particular device, these depictions are for illustrative purposes only. Functions described in this invention as being performed by a single component can be performed by multiple components in a distributed manner. Similarly, functions performed by multiple components can be combined and performed by a single component. In some embodiments, the components shown can be combined or divided into separate software, firmware, and / or hardware. For example, logic and processing can be distributed among multiple electronic processors, rather than residing within and being performed by a single electronic processor. Regardless of how the hardware and software components are combined or divided, they can reside on the same computing device or be distributed among different computing devices connected via one or more networks or other suitable communication links. Similarly, components described as performing specific functions can also perform additional functions not described in this invention. For example, a device or structure "configured" in a certain way is at least configured in that manner, but can also be configured in a manner not explicitly listed.

[0035] Therefore, in the claims, if the device, method, or system is claimed to include, for example, a controller, control unit, electronic processor, computing device, logic element, module, memory module, communication channel or network, or other elements configured in a certain way to perform, for example, multiple functions, then the claims or claim elements should be interpreted as referring to one or more such elements, any one of which is configured to, for example, implement any one or more of the multiple functions, such that the one or more elements together perform the multiple functions.

[0036] Other examples, implementations, features, and aspects will become apparent from the detailed description and accompanying drawings. Attached Figure Description

[0037] Figure 1 It is an isometric view based on some examples of power tools.

[0038] Figure 2 It is an isometric view of a battery pack based on some examples.

[0039] Figure 3 This is a block diagram illustrating a control system for power tools, based on some examples.

[0040] Figure 4 This is a circuit diagram illustrating the topology of a gate controller and switching network according to some examples.

[0041] Figure 5 This is a circuit diagram showing the current flow path through a switching network according to some examples.

[0042] Figure 6 This is a circuit diagram showing the current flow path through a switching network according to some examples.

[0043] Figure 7 This is a circuit diagram showing the current flow path through a switching network according to some examples.

[0044] Figure 8 This is a circuit diagram showing the current flow path through a switching network according to some examples.

[0045] Figure 9 This is a block diagram illustrating the topology of a controller for implementing field-oriented control, based on some examples.

[0046] Figure 10 This is a flowchart illustrating a process for controlling a motor, based on some examples.

[0047] Figure 11 This is a state diagram showing various operating states of power tools based on some examples.

[0048] Figure 12 This is a flowchart of a process for implementing an electronic clutch function, based on some examples.

[0049] Figure 13 This is a block diagram illustrating the components of a torque estimation model based on some examples.

[0050] In the accompanying drawings, reference numerals may be used repeatedly to identify similar and / or identical elements. Detailed Implementation

[0051] Figure 1 This is an isometric view of a power tool 100 based on some examples. Figure 1 In the example, power tool 100 is implemented as a drill / drive. Although in Figure 1In one example, power tool 100 is implemented as a drill / driver; however, in other examples, power tool 100 may be implemented as any of a variety of other power tools. In various embodiments, power tool 100 is configured as a drill, perforator, impact driver, impact wrench, hammer drill, or other fastening or drilling tool. In some examples, power tool 100 is implemented as a cutting or grinding tool, such as a circular saw, wire saw, band saw, angle grinder, or straight grinder. In various embodiments, power tool 100 is implemented as a fastening tool, such as, for example, a screwdriver, electric ratchet, electric torque wrench, nail gun, staple gun, or TC bolt gun. In some examples, power tool 100 is a special-purpose tool, such as a rotary hammer, angle drill, locking bolt installation tool, reaction arm tool, riveting tool, or other special-purpose power tool. The specific implementation of power tool 100 can vary depending on the intended application and functional requirements.

[0052] exist Figure 1 In the example, power tool 100 includes a body 102, a handle 104, and a battery pack interface 106. Power tool 100 also includes one or more user inputs, such as a trigger 108, a forward / reverse selector 110, a torque selector 112, and a range selector 114. Figure 1 In this example, trigger 108 is implemented as a sliding variable position switch that adjusts the motor speed based on user actuation. Forward / reverse selector 110 is implemented as a multi-position switch that allows the user to select the direction of motor rotation. Torque selector 112 is implemented as a multi-position switch or variable resistance potentiometer that allows the user to adjust the torque output across predefined or continuously variable settings. Range selector 114 is implemented as a multi-position switch that allows the user to select different torque ranges for torque selector 112. In other examples, the user input section may be implemented with different configurations depending on the application.

[0053] The power tool 100 also includes an output element 116. Figure 1 In one example, output element 116 is implemented as a tool head retainer configured to hold the drill bit or driver head. In other examples, depending on the type of power tool and its application, output element 116 may be implemented as a sleeve retainer, chuck, collet, insert mount, grinding wheel interface, or other fastening mechanism.

[0054] Power tool 100 may include a motor and a controller. Figure 1(Not shown in the image). In various embodiments, the motor and controller are located within the main body 102. The controller can receive input from one or more user input sections and adjust the motor operation accordingly. For example, the actuation trigger 108 corresponds to selecting the motor speed, while engagement of the forward / reverse selector 110 determines the direction of rotation. The controller can adjust the motor speed based on the trigger position and maintain the selected direction based on the forward / reverse selector 110.

[0055] Users can adjust torque settings using a combination of torque selector 112 and range selector 114. For example, torque selector 112 allows the user to select a specific torque limit, while range selector 114 modifies the available total torque range. For instance, range selector 114 can switch between a low torque range and a high torque range, allowing torque selector 112 to adjust within the selected range. The controller can interpret these selections and adjust motor operation accordingly to provide the torque output corresponding to the selected settings.

[0056] The motor can be mechanically coupled to a drive mechanism (e.g., a transmission), which can then be coupled to the output element 116. The motor transmits mechanical power to the drive mechanism, which in turn transmits mechanical power to the output element 116. In various embodiments where the power tool 100 is configured as a drill / drive, the drive mechanism may include a series of gears that transmit rotational motion from the motor to the output element 116 while adjusting speed and torque characteristics. For example, the motor may drive pinions meshing with an intermediate gear train or a planetary gear system. These gears can change the speed and torque before transmitting mechanical power to the spindle that rotates the output element 116.

[0057] As will be explained in detail, the controller can implement the function of an electronic clutch. For example, the controller can set a torque threshold based on a combination of user inputs via torque selector 112 and range selector 114. The controller can estimate the torque output via output element 116. In response to the estimated torque output exceeding the threshold, the controller can brake the motor, interrupting the torque transmitted from the motor to output element 116.

[0058] Figure 2 This is an isometric view of a battery pack 200 based on some examples. Battery pack 200 may be a power tool battery pack configured to power a power tool (such as power tool 100). Figure 2In one example, battery pack 200 includes a housing 202 and an interface portion 204 for connecting battery pack 200 to power tool 100. Battery pack 200 may include one or more battery cells housed within housing 202. For example, battery pack 200 may include lithium-ion battery cells. In other embodiments, battery pack 200 may include batteries with different chemical systems, such as nickel-cadmium, nickel metal hydride, or other rechargeable battery technologies.

[0059] exist Figure 2 In this example, battery pack 200 is an 18-volt battery pack. In other embodiments, battery pack 200 may have different nominal voltages. For example, battery pack 200 may be configured as a 4-volt, 28-volt, 36-volt, 72-volt, 96-volt, or 120-volt battery pack, or another voltage level based on the design requirements of the power tool. Battery pack 200 may also have different energy storage capacities, such as 3, 4, 5, 6, 8, or 12 ampere-hours, depending on the number and type of battery cells used.

[0060] Interface portion 204 may include elements for removably and securely connecting battery pack 200 to power tool 100 and / or facilitating electrical and data communication between battery pack 200 and power tool 100. In various embodiments, interface portion 204 may include mechanical features, such as latches, tracks, or locking tabs, that engage with corresponding features at battery pack interface 106 of power tool 100. These mechanical features can help align battery pack 200 with battery pack interface 106 and provide a secure attachment during operation.

[0061] Interface portion 204 may also include electrical terminals for supplying power to power tool 100. In some examples, these terminals include positive and negative terminals connected to battery pack interface 106 to deliver power from battery pack 200 to power tool 100. In various embodiments, interface portion 204 may also include data terminals for communication between battery pack 200 and power tool 100. For example, battery pack 200 may include a microcontroller that monitors characteristics such as voltage, current, temperature, or capacity. Data terminals can facilitate the transmission of such information to power tool 100, allowing the tool's controller to adjust operation based on battery status.

[0062] Figure 3This is a block diagram illustrating a control system 300 for a power tool 100 according to some examples. In various embodiments, portions of the control system 300 may be integrated into or connected to a printed circuit board (PCB) and may include an electronic controller 302. The electronic controller 302 may include hardware and / or software designed to manage the operation of various components of the power tool 100. The electronic controller 302 may include various electrical and / or electronic components that provide power, operation control, and / or protection to the electronic controller 302 and / or components and / or modules within the power tool 100. For example, the electronic controller 302 includes a processing unit 304 (such as a microprocessor, microcontroller, electronic processor, electronic controller, or other suitable programmable device), a memory 306, an input unit 308, and / or an output unit 310. The processing unit 304 may include a control unit 312, an arithmetic logic unit (ALU) 314, and / or a register set 316 (in Figure 3 The processing unit 304 is a component (described as a set of registers). It can utilize computer architectures such as a modified Harvard architecture, von Neumann architecture, or other suitable architectures.

[0063] Processing unit 304, memory 306, input unit 308, output unit 310, and / or other modules connected to electronic controller 302 can be interconnected via one or more control and / or data buses, such as common bus 318. Although for illustrative purposes... Figure 3 These buses are roughly illustrated, but those skilled in the art will recognize, given the embodiments described herein, that one or more control and / or data buses are used for interconnection and communication between various modules and / or components.

[0064] Memory 306 is a non-transitory computer-readable medium that includes, for example, a program storage area and / or a data storage area. The program storage area and data storage area may include any combination of different types of memory, such as read-only memory (ROM), random access memory (RAM), such as dynamic RAM (DRAM), synchronous DRAM (SDRAM), electrically erasable programmable read-only memory (EEPROM), flash memory, one or more hard disk drives, one or more SD cards, and / or other suitable magnetic, optical, physical, and / or electronic memory devices. Processing unit 304 is connected to memory 306 and configured to execute software instructions capable of being stored in the RAM of memory 306 (e.g., during execution), the ROM of memory 306 (e.g., on a substantially permanent basis), and / or another non-transitory computer-readable medium such as another memory or disk.

[0065] The software stored in memory 306 can control various functions of the power tool 100. For example, the function blocks, flowchart elements, and technical specifications described in this invention can be used as software specifications, which have been translated into computer programs. This software may include firmware, applications, program data, filters, rules, program modules, and / or other executable instructions. The electronic controller 302 can retrieve and execute these instructions to control the operation of the power tool 100. In other configurations, depending on the specific implementation, the electronic controller 302 may include additional, fewer, and / or different components.

[0066] The electronic controller 302 can be electrically and / or communicatively connected to various modules and / or components of the power tool 100 and / or control the operation of these modules and / or components. Figure 3 In one example, power tool 100 includes a power input module 320 that regulates and manages the power delivered from battery pack interface 106 to electronic controller 302 and other components of power tool 100. For example, power input module 320 receives direct current (DC) power from battery pack 200 via electrical terminals. Power input module 320 may include a combination of active and passive components, such as voltage regulators, current limiters, capacitors, and / or filtering circuitry to regulate the voltage to the appropriate level required by electronic controller 302 and / or other components. In various embodiments, power input module 320 filters noise from the DC power before providing filtered power to electronic controller 302 and / or other components.

[0067] exist Figure 3 In the example, the power tool 100 includes a gate controller 322 and a drive motor 326 (as previously referenced). Figure 1 The motor 326 includes a switching network 324. The motor 326 comprises a rotor, a stator, and a shaft. The stator is the stationary part of the motor 326 and includes coils (which may be referred to as windings) through which current flows to generate a rotating magnetic field. The rotor may be positioned within or around the stator and is a moving part that rotates under the influence of the magnetic field generated by the stator. The rotor may be connected to a shaft that rotates about a longitudinal axis, transmitting the mechanical forces generated by the motor 326 to a drive mechanism.

[0068] Motor 326 can be electrically connected to and receive power from switch network 324. Switch network 324 can receive direct current (DC) from battery pack 200 via battery pack interface 106 and can convert DC into a phase signal. The phase signal can be applied to the stator windings in a controlled sequence to generate a magnetic field that drives the rotor to rotate. For example, gate controller 322 can be electrically connected to switch network 324 and regulate the operation of switches (such as field-effect transistors [FETs]) within switch network 324 to determine when and how DC power is converted into a phase signal. Electronic controller 302 can be electrically connected to gate controller 322 and generate control signals and send control signals to gate controller 322, instructing gate controller 322 how to manage the operation of the switches in switch network 324. The timing and modulation of the switches in switch network 324 allow for precise adjustment of the frequency and amplitude of the power supplied to motor 326, which allows for precise control of the speed, torque, and direction of motor 326.

[0069] In various implementations, the power tool 100 employs advanced control techniques such as field-oriented control to precisely manage the operation of the motor 326. Field-oriented control allows for independent control of torque and flux by mathematically converting the three-phase current signals into a rotating reference frame aligned with the rotor magnetic field. This provides superior dynamic response and efficiency compared to other control methods. As part of this control strategy, the power tool 100 may also implement field weakening to facilitate operation of the motor 326 beyond its base speed under various operating conditions. Field weakening is implemented to achieve higher output speeds at the motor 326 by reducing the strength of the magnetic field generated by the stator. This is achieved by adjusting the phase signal applied to the stator windings, for example, by applying a negative direct-axis current to reduce the stator's magnetic field strength, thereby reducing the back electromotive force and allowing for higher speeds.

[0070] The electronic controller 302 can implement field-oriented control (FOC) to regulate the operation of the motor 326 by independently controlling the torque-generating and excitation components of the stator current. In various embodiments, the electronic controller 302 can transform the motor phase currents into a rotating reference frame, where the direct-axis (d-axis) component regulates the excitation flux linkage, and the quadrature-axis (q-axis) component determines the torque output of the motor 326. By dynamically adjusting these current components, the electronic controller 302 can optimize motor performance across different operating conditions.

[0071] For example, electronic controller 302 can send control signals to gate controller 322, which adjusts the phase signal output from switching network 324 to achieve magnetic field weakening by dynamically changing the current applied to the stator windings of motor 326. During high-speed operation, electronic controller 302 can command gate controller 322 to reduce the d-axis current while increasing the rotor speed. This reduces the magnetic flux in motor 326, which limits the back electromotive force (EMF) induced in the stator windings, allowing motor 326 to operate at higher speeds without exceeding the voltage limits of battery pack 200 or switching network 324. Additional details related to field-oriented control will be described in the present invention.

[0072] In various embodiments, the power tool 100 includes one or more sensors 328 that provide feedback to an electronic controller 302 for motor control and system monitoring. These sensors 328 may include a position sensor 330, a current sensor 332, and / or a voltage sensor 334, which can provide data for implementing field-oriented control. The electronic controller 302 can receive sensor signals from these sensors to regulate the operation of the motor 326, optimize efficiency, and protect system components.

[0073] In various embodiments, sensor 328 (including, for example, current sensor 332 and voltage sensor 334) may be configured to monitor one or more electrical parameters and / or electrical characteristics of motor 326. Such electrical parameters or characteristics may include, for example, current, voltage, back electromotive force (EMF), power, or other electrical characteristics associated with the operation of motor 326.

[0074] For example, position sensor 330 can detect the angular position and speed of the rotor, allowing electronic controller 302 to synchronize the phase current with the rotor's magnetic field. In various embodiments, position sensor 330 includes encoders, resolvers, or Hall effect sensors, all of which directly determine the rotor position. Alternatively, sensorless estimation techniques can be used, where controller 302 infers the rotor position based on back electromotive force or motor current feedback.

[0075] Current sensor 332 measures the current supplied to the stator windings of motor 326. These measurements allow electronic controller 302 to determine the d-axis and q-axis components of the motor current in a transformed reference frame. By adjusting the d-axis and q-axis current components based on the measured values, electronic controller 302 can independently adjust torque and flux. In various embodiments, current sensor 332 includes a shunt resistor, Hall effect current sensor, or fluxgate sensor placed in the motor drive circuit to monitor phase current.

[0076] Voltage sensor 334 can track the voltage supplied by battery pack 200 and / or the voltage across the terminals of motor 326. During high-speed operation, these measurements allow electronic controller 302 to adjust control strategies, such as field weakening. For example, by monitoring back electromotive force and DC bus voltage, the controller can ensure that voltage limits of battery pack 200 and switching network 324 are not exceeded. Voltage sensor 334 may include a resistive voltage divider, isolation amplifier, or other voltage sensing circuitry.

[0077] Sensor 328 may include additional sensors for broader system monitoring and control. In some examples, sensor 328 may include a temperature sensor for monitoring motor 326 or switch network 324, a torque sensor for measuring torque output at motor shaft, an acceleration sensor for detecting rapid changes in speed or direction, and a vibration sensor for monitoring excessive vibrations that may indicate mechanical wear or imbalance. Other examples of sensor 328 include proximity sensors, strain gauges, optical sensors, and gyroscope sensors, depending on the application and design requirements of power tool 100.

[0078] The electronic controller 302 may be electrically connected to one or more user input units 336. The user input unit 336 may include triggers 108, forward / reverse selectors 110, torque selectors 112 and / or range selectors 114, and / or any combination of digital and / or analog devices, including knobs, dials, switches, buttons, touchscreens, etc. In various embodiments, the controller 302 detects user interaction with the user input unit 336 and changes the operating parameters of the motor 326 (such as starting the motor, stopping the motor, adjusting the motor speed, adjusting the motor output torque, adjusting the torque threshold of the electronic clutch, switching the motor's rotation direction, etc.).

[0079] In some examples, the power tool 100 includes a communication interface 338, such as Bluetooth, Wi-Fi, and / or other wireless communication modules. The communication interface 338 allows the electronic controller 302 to receive wireless signals from external devices (such as smartphones, tablets, or other control systems) and control various operational aspects of the power tool 100 accordingly.

[0080] In various embodiments, the power tool 100 includes one or more indicators 340. Indicators 340 may include various types of display elements, such as light-emitting diodes (LEDs), displays, or other types of visual or auditory indicators. Indicators 340 may be electrically connected to an electronic controller 302, and the electronic controller 302 may control the indicators to output to the user the operating status of the power tool 100 (such as indications of motor operation, motor idle, battery state of charge, low battery warning, charging status, fault detection, motor overload, over-temperature warning, mode selection [e.g., forward / reverse], torque setting, and / or maintenance or upkeep alarms, etc.).

[0081] In various embodiments, the power tool 100 includes one or more indicators 340 that provide audio, visual, and tactile feedback to communicate operating status to the user. These indicators 340 may be electrically connected to an electronic controller 302, which may control them based on real-time tool status. Audio indicators may include speakers or buzzers that produce tones, beeps, or voice alarms. Visual indicators may include light-emitting diodes (LEDs) or displays that present status information through illumination signals, icons, or text. Tactile indicators may include haptic engines that generate vibrations to provide tactile feedback.

[0082] Indicator 340 can output the operating status of power tool 100. For example, a speaker can emit beeps or voice messages to indicate warnings, confirmations, or tool settings. LEDs can light up, flash, or change color to indicate different states, while a display screen can show numerical values, graphical icons, or system messages. A haptic engine can provide brief or continuous vibrations to signal specific tool conditions. Indicator 340 can convey various states, such as motor running, motor idle, battery state of charge, low battery warning, charging status, fault detection, motor overload, over-temperature warning, mode selection (e.g., forward / reverse), torque setting, and maintenance or upkeep warnings. In various embodiments, indicator 340 provides feedback related to the electronic clutch. For example, when the torque limit is reached, the haptic engine can generate vibrations, the speaker can emit an alarm sound, and the LEDs or display screen can signal that torque transmission has been interrupted.

[0083] Figure 4 This is a circuit diagram 400 illustrating the topology of a gate controller 322 and a switching network 324 according to some examples. The switching network 324 includes one or more high-side switching elements 402 and one or more low-side switching elements 404. In various embodiments, the high-side power switching element 402 and the low-side power switching element 404 are implemented using field-effect transistors (FETs) such as MOSFETs (metal-oxide-semiconductor FETs) or IGBTs (insulated-gate bipolar transistors).

[0084] The electronic controller 302 can command the gate controller 322 to provide control signals that selectively activate and deactivate the high-side switching element 402 and the low-side switching element 404. In response to detecting activation of the trigger 108, the electronic controller 302 can initiate a sequence in which power from the power source 406 (e.g., battery pack 200) is applied to the stator windings of the motor 326 in a controlled manner.

[0085] For example, electronic controller 302 can determine the rotor position based on pulse signals from sensor 328 and command gate controller 322 to sequentially activate pairs of high-side switching elements 402 and low-side switching elements 404. This switching sequence generates a rotating magnetic field in the stator, which interacts with the rotor to sense motion. As the rotor advances, controller 302 continues to update the switching signals based on sensor feedback to ensure that commutation remains aligned with the rotor's position.

[0086] To regulate motor speed and torque, electronic controller 302 can adjust the pulse width modulation (PWM) duty cycle of the switching signal. In various embodiments, the duty cycle can be proportional to the trigger pull of trigger 108, allowing for fine control of the power delivered to motor 326.

[0087] Sensor feedback can also support field-oriented control (FOC), allowing the electronic controller 302 to independently adjust the torque generation component and the excitation current component. The current sensor 332 can measure the stator phase current, and the controller 302 can convert the stator phase current into a rotating reference frame to separate them into direct-axis currents (i...). d ) and quadrature axis current (i q i d Component control of excitation flux, while i q Component-controlled torque generation. This is achieved by adjusting i... d and i q The component controller 302 can extend the speed range of the motor 326 under varying operating conditions.

[0088] For example, during high-speed operation, the electronic controller 302 can reduce i d This achieves magnetic field weakening, which reduces the overall flux linkage and helps limit the back electromotive force. This reduction in flux lowers the back electromotive force, allowing the motor 326 to operate at higher speeds without exceeding the voltage constraints imposed by the battery pack 200 and the switching network 324. Simultaneously, the controller 302 can adjust i q This is to regulate torque output, ensuring stable performance while maintaining efficient power consumption.

[0089] The number, type, and arrangement of the high-side switching element 402 and the low-side switching element 404 can vary depending on the application and power requirements of the power tool 100. Alternative configurations can be combined with different switching topologies or additional protection components to improve efficiency and reliability.

[0090] Figure 5 This is a circuit diagram 500 illustrating current flow paths through a switching network 324 according to some examples. As described above, the switching network 324 may include one or more high-side switching elements 402 and one or more low-side switching elements 404. For example, in response to detecting a pull of the trigger 108, the controller 302 may command the gate controller 322 to provide one or more control signals (e.g., sequentially, in pairs) to selectively activate and deactivate the high-side switching element 402 and the low-side switching element 404. This switching sequence may enable power to be supplied from the power supply 406.

[0091] In various implementations, current 502 can flow from power supply 406 through one of the high-side switching elements 402 to the stator coil of motor 326. Then, current 502 can flow from motor 326 to one of the low-side switching elements 404 before completing its conductive path 504 to power supply 406. The specific current flow path and switching sequence can vary based on factors such as motor location, load conditions, and control strategy.

[0092] Figure 6 This is a circuit diagram 600 illustrating current flow paths through a switching network 324 according to some examples. As described above, the switching network 324 may include one or more high-side switching elements 402 and one or more low-side switching elements 404. For example, in response to detecting a pull of trigger 108, controller 302 may command gate controller 322 to provide one or more control signals (e.g., sequentially, in pairs) to selectively activate and deactivate high-side switching elements 402 and low-side switching elements 404. This switching sequence may enable power to be supplied from power source 406.

[0093] In various implementations, current 502 can flow from power supply 406 through one of the high-side switching elements 402 to one of the low-side switching elements 404. Current 502 can then return to power supply 406, forming a complete loop. Compared to other switching configurations, this current path may involve only two switching elements and can make the conductive path 504 through the switching network 324 shorter.

[0094] In some examples, multiple high-side switching elements 402 and / or multiple low-side switching elements 404 can be activated simultaneously. This control method can reduce the overall system resistance, allowing higher current flow while distributing the electrical load across multiple switching elements. Distributing the load in this way can help manage heat dissipation and reduce the likelihood of overheating or wear in individual switching elements.

[0095] Figure 7 This is a circuit diagram 700 illustrating the current flow path through a switching network 324 according to some examples. Figure 7 In the example, the additional switching element 702 is connected within the connection path of the conductive path 504. Along with the additional switching element 702, an additional resistor is also connected to the connection path of the conductive path 504.

[0096] For example, in response to detecting a pull of trigger 108, controller 302 can command gate controller 322 to provide one or more control signals to selectively activate and deactivate switching element 702, allowing power to be supplied from power source 406. In this configuration, current 502 can flow from power source 406 through an additional resistor and then through additional switching element 702. In this example, current 502 can travel only through the additional resistor and additional switching element 702 before returning to power source 406, thus forming a complete loop.

[0097] In various implementations, inductors can be used instead of additional resistors to achieve similar electrical characteristics. Additionally, depending on the specific application and design considerations, other circuit configurations can incorporate alternative components such as capacitors.

[0098] Figure 8 This is a circuit diagram 800 illustrating the current flow path through a switching network 324 according to some examples. Figure 8 In the example, a single power switching element 404 is used. For example, in response to detecting a pull of trigger 108, controller 302 may command gate controller 322 to provide one or more control signals to selectively activate and deactivate power switching element 404, so that power is supplied from power source 406.

[0099] In this configuration, current 502 can flow from power source 406 to motor 326 and then to power switching element 404 before forming a complete loop through the path connected by conductive path 504. The specific current and switching sequence can vary depending on motor characteristics, control strategy, and application requirements.

[0100] Figure 9 This is a block diagram 900 illustrating a topology for implementing field-oriented control for controller 302, based on some examples. Figure 9In the example, to implement field-oriented control, controller 302 receives position and current signals from power tool 100 and generates corresponding pulse-width modulation (PWM) control signals for gate controller 322. Position sensor 330 can detect the angular position of the rotor relative to the stator and output the position signal to sensor decoder 902.

[0101] The sensor decoder 902 can generate the mechanical motor angle (θ) based on the position signal. m ), and θ m The simultaneous measurement results are output together to the velocity measurement box 904. The velocity measurement box 904 can be based on the mechanical motor angle (θ). m The rotor speed of motor 326 is calculated using timing data and a motor speed signal (ω) is generated. fb Then the motor speed signal (ω) can be used. fb Send to speed control box 906.

[0102] Speed ​​control block 906 can determine the motor speed feedback signal (ω) fb ) and reference velocity (ω) ref The difference between the reference velocity (ω) and the reference velocity (ω). ref This can correspond to the speed command received from the speed change trigger 108. Based on the speed difference, the speed control block 906 can generate a torque control signal (T). ref And provide the signal to the dq control reference generator 908.

[0103] In various implementations, the dq control reference generator 908 can incorporate additional control strategies, such as modulation index control, maximum torque per ampere (MTPA) control, or field weakening control. This block can calculate the d-axis and q-axis currents required to achieve the desired torque and speed. The d-axis represents the direct axis aligned with the rotor flux, while the q-axis represents the quadrature axis, leading the d-axis by 90 degrees and corresponding to the torque generation component of the motor 326.

[0104] The dq control reference generator 908 can be based on the torque control signal (T) ref ) and reference velocity (ω) ref To generate the q-axis control current (I) q,ref ) and d-axis control current (I d,ref These values ​​can be determined by factors such as the desired speed, the motor's base speed, and control parameters. q-axis control current (I) q,ref The current (I) can be supplied to the q-axis adjuster 910, while the d-axis control current (I) d,refThe speed control block 906, the dq control reference generator 908, the q-axis controller 910, and the d-axis controller 912 together allow for independent torque-speed control of the motor 326, unlike other motor drive technologies such as trapezoidal wave commutation or square wave commutation.

[0105] The sensor decoder 902 can also detect the mechanical motor angle (θ). m The output is sent to the electrical angle conversion box 914. This box can convert the mechanical rotor angle (θ) to an electrical angle conversion box. m ) converted into electric rotor angle (θ) e This information is then fed into the sine-cosine lookup box 916. The sine-cosine lookup box 916 can calculate the electric rotor angle (θ). e The sine and cosine of the expression are calculated and output to both the Parker Transform 918 and the inverse Parker Transform 920.

[0106] In this example, controller 302 receives two instantaneous line currents (I0, I ...) from switch network 324. a and I b In various implementations, different sets of line currents can be received. Two phases of the three-phase motor 326 can generate these line currents. The Clarke converter block 922 can convert the line current (I... a and I b ) converted into current (I) in α-β coordinate system α and I β The α-β coordinate system provides a simplified two-phase representation of the three-phase motor 326. The Clarke transform box 922 can convert the quadrature currents (I...) α and I β Output to Parker Transformer 918.

[0107] Parker transform box 918 can receive quadrature line current (I) from sine-cosine lookup box 916. α and I β ) as well as sine and cosine signals. Using these inputs, the Parker Transform 918 can generate orthogonal d-axis and q-axis currents (Id and Iq). d and I q This can represent the transformed phase current in a rotating reference frame. The Parker transform block 918 can transform the q-axis current (I...) q The output is sent to the q-axis regulator 910 and the d-axis current (I) is also sent to the q-axis regulator 910. d The output is sent to the d-axis adjuster 912.

[0108] The q-axis regulator 910 can calculate the error between the desired q-axis current and the actual q-axis current. The q-axis regulator 910 can receive the q-axis control current (Iq) from the dq control reference generator 908. q,refAnd receive the q-axis current (I) from the Parker transformer 918. q Based on these inputs, the q-axis regulator 910 can calculate the current error and apply a proportional-integral (PI) controller to generate a q-axis voltage control signal (V). q,ref This signal can be provided to the inverse Parker transformer 920.

[0109] Similarly, the d-axis regulator 912 can adjust the d-axis current. The d-axis regulator 912 can receive the d-axis control current (Iq) from the dq control reference generator 908. d,ref And receive d-axis current (I) from Parker transformer 918 d Using these inputs, the d-axis regulator 912 can calculate the current error and apply a PI controller to generate a d-axis voltage control signal (V). d,ref This signal can also be sent to the inverse Parker transformer 920.

[0110] The inverse Parker transformer 920 can convert the q-axis voltage control signal (V) q,ref ) and d-axis voltage control signal (V d,ref ) is converted into a simplified α-β quadrature voltage (V α and V β These voltages can then be sent to the PWM generator 924, which can then base its output on the input voltage (V). α and V β It generates PWM control signals. The PWM generator 924 can output these PWM control signals to the gate controller 322.

[0111] The gate controller 322 can convert the PWM control signal into discrete control signals for driving the switching elements in the switching network 324, such as six separate voltage switching signals (PWM gate signals). In some examples, the PWM signal operates at a frequency of at least 50 kHz. In various implementations, depending on the system's control requirements and switching characteristics, the PWM frequency can be lower than 250 kHz.

[0112] Figure 10 This is a flowchart illustrating a process 1000 for controlling motor 326 according to some examples. Although the process 1000 is shown to operate with reference to specific examples, the process can be applied in different contexts to perform various motor control tasks. Figure 10 The order of operations shown is presented in a specific order, but for a given implementation, these operations can be reordered, executed in parallel, or repeated.

[0113] In some examples, process 1000 can be executed by controller 302 using the controller topology shown in block diagram 900 to achieve field-oriented control, such as in combination with Figure 9 As described above. However, other implementations may use different configurations. In example process 1000, controller 302 receives a speed command (at block 1002). The speed command may be generated based on user input, such as from shift trigger 108 or another speed selection mechanism. In some examples, controller 302 may determine the speed command based on operating parameters and power tool conditions. If a speed command is received from trigger 108, the trigger switch can convert the degree of trigger actuation into a corresponding speed command, which can serve as a speed reference (ω). ref The signal is provided to the controller 302. In various embodiments, the controller 302 may receive signals from the trigger 108 and generate a speed reference (ω) based on those signals. ref ).

[0114] In example process 1000, controller 302 generates control reference signals based on the speed command (at block 1004). In various implementations, these control reference signals are associated with field-oriented control. See also Figure 9 The speed control block 906 can receive speed commands and generate a field-oriented control torque reference signal (T) based on the received speed commands. ref The speed control block 906 can also receive the motor speed measurement result from the speed measurement block 904 and generate a field-oriented control torque reference signal to reduce the difference between the speed command and the measured motor speed. Then, the dq control reference generator 908 can receive the field-oriented control torque reference signal and generate a field-oriented control current reference signal (I). q,ref and I d,ref The dq control reference generator 908 can determine these reference currents based on both the speed command and the field-oriented control torque reference signal.

[0115] In various implementations, controller 302 can determine whether the speed command is greater than or equal to the base speed of motor 326. The base speed of the motor can be defined as the maximum speed at which the motor operates while delivering its rated torque. If the speed command exceeds the base speed, controller 302 can reduce the torque to maintain the commanded speed. Controller 302 can retrieve the base speed value from memory 306 and compare it with the speed command.

[0116] The method used to generate the field-oriented control reference signal can vary depending on whether the speed command is higher or lower than the base speed of the motor 326. In some examples, when the speed command is lower than the base speed, the dq control reference generator 908 can use maximum torque per ampere (MTPA) control to generate the field-oriented control reference signal. When the speed command exceeds the base speed, the dq control reference generator 908 can use field weakening control to generate the field-oriented control reference signal to reduce torque while maintaining a higher speed.

[0117] In example process 1000, controller 302 generates a PWM control signal based on a reference signal (at block 1006). A field-oriented control current reference signal can be sent to q-axis regulator 910 and d-axis regulator 912, which can calculate the error between the reference signal and the measured current between switch network 324 and motor 326. PWM generator 924 can receive these error signals and generate PWM control signals accordingly. For example, the PWM control signal can be adjusted to minimize the error by dynamically modifying the duty cycle of the PWM pulses based on the error magnitude.

[0118] In example process 1000, controller 302 can command gate controller 322 to control the switching elements of switching network 324 (at block 1008) according to PWM control signals, for example, according to any of the techniques described above. The switching elements can alternate between on and off states to regulate current flow between the power supply and motor 326. A PWM output from controller 302 (or from PWM generator 924) can be connected to the input of gate controller 322. Depending on the system configuration, gate controller 322 can receive PWM control signals and convert them into gate drive signals for individual switching elements or pairs of switching elements. These gate drive signals can then be applied to the switching elements.

[0119] Figure 11 This is a state diagram 1100 showing various operating states of a power tool 100 according to some examples. Figure 11 Each box in the diagram represents a different state that the power tool 100 can transition between based on user input, operating conditions, and control logic. Transitions between states can occur in response to factors such as trigger activation, torque threshold detection, battery status, and fault conditions. In various implementations, the controller 302 can monitor these inputs and perform state transitions to regulate motor operation, torque output, and other tool functions.

[0120] In example state diagram 1100, power tool 100 includes an idle state 1102, an initial trigger pull response state 1104, a drive state 1106, a braking state 1108, an end indication state 1110, and a continue drive state 1112. When power tool 100 is powered on and initialized but not running (e.g., controller 302 does not receive a command from user input unit 336), power tool 100 can be in idle state 1102. In idle state 1102, controller 302 does not command motor 326 to operate (e.g., does not command quadrature axis current [i]). q or direct-axis current [i d ]).

[0121] When the user actuates trigger 108, the power tool 100 can transition from an idle state 1102 to an initial trigger pull response state 1104. In this state, the controller 302 can disable the electronic clutch function for an initial time period (e.g., approximately 5 to 50 milliseconds) after trigger actuation. In response to trigger 108 remaining actuated beyond this initial time period, the power tool 100 can transition to a drive state 1106.

[0122] In drive state 1106, controller 302 operates motor 326 according to user input, such as maintaining a desired speed. In this state, controller 302 can monitor signals from sensor 328 and implement electronic clutch function based on these monitored signals.

[0123] Figure 12 This is a flowchart of process 1200 for implementing an electronic clutch function, based on some examples. Although process 1200 is shown to operate with reference to a specific example, the process can be applied to different contexts. Figure 12 The sequence of operations shown is presented in a specific order, but for a given implementation, these operations can be reordered, executed in parallel, or repeated.

[0124] In example process 1200, controller 302 monitors the current component of motor 326 (at block 1202). In an implementation where controller 302 uses field-oriented control, controller 302 can determine the quadrature-axis current (i) based on the signal from current sensor 332. q ) and direct-axis current (i d The current sensor 332 can measure the phase current at motor 326, and then the phase current can be transformed to the dq reference frame using the Clarke transform (to α-β coordinates) and the Park transform (to dq coordinates). Direct-axis current (i...) d ) can correspond to magnetic flux, while quadrature-axis current (i q This can correspond to the torque generation component.

[0125] In example process 1200, controller 302 monitors the rotational speed (ω) of motor 326 (at block 1204). Controller 302 can determine the motor speed based on signals from position sensor 330. In various embodiments, rotational speed (ω) can be expressed in revolutions per minute (RPM), radians per second (rad / s), degrees per second (deg / s), hertz (Hz), or revolutions per second (RPS).

[0126] Additionally or alternatively, signals from current sensor 332 and / or voltage sensor 334 can also be used to estimate the rotational speed of motor 326. For example, in embodiments using sensorless estimation techniques, electronic controller 302 can calculate or infer rotor speed based on back electromotive force (EMF), which can originate from voltage and current measurements. During operation, controller 302 can monitor the voltage across the motor terminals using voltage sensor 334 and monitor phase current using current sensor 332. By analyzing the relationship between terminal voltage, phase current, and motor parameters such as inductance and resistance, controller 302 can estimate the back EMF generated by motor 326. Since the magnitude and frequency of the back EMF may be directly related to the rotor speed, controller 302 can use this information to estimate motor speed in real-time or near real-time.

[0127] In example process 1200, controller 302 estimates the output torque (at block 1206). The estimated output torque can be based on the monitored current component and rotational speed to estimate the torque at output element 116. In various embodiments, controller 302 can use a torque estimation model to calculate the estimated output torque.

[0128] Figure 13 This is a block diagram 1300 illustrating the components of a torque estimation model 1302 according to some examples. The torque estimation model 1302 includes a motor torque component 1304 and a parasitic torque loss component 1306. The motor torque component 1304 represents an estimated value of the torque output from the motor 326, while the parasitic loss component 1306 represents the losses in torque transmission between the motor 326 and the output element 116. In various embodiments, the parasitic loss component 1306 may include an inertial component 1308, a wind resistance component 1310, and a friction component 1312.

[0129] The motor torque component 1304 can be based on the quadrature-axis current (i) at motor 326. q ) and direct-axis current (i d The electromagnetic torque (T) can be estimated, as calculated by the controller 302 from the measured phase current. In various embodiments, when the motor 326 is a brushless DC motor (BLDC) or a surface permanent magnet synchronous motor (SPMSM), the controller 302 can use equation (1) to estimate the electromagnetic torque (T). e ): (1) As shown in equation (1), controller 302 can control the electromagnetic torque (T) e The estimated number of pole pairs for motor 326 (P) m ), permanent magnet flux linkage (λ) of motor 326 m ) and the quadrature axis current (i) at motor 326 q The function of ).

[0130] For the implementation where motor 326 is an internal permanent magnet synchronous motor (IPMSM), controller 302 can estimate the torque using equation (2): (2) As shown in equation (2), the controller 302 can control the electromagnetic torque (T) e The estimated number of pole pairs for motor 326 (P) m ), permanent magnet flux linkage (λ) of motor 326 m ), the quadrature axis current at motor 326 (i q ), the direct-axis inductance of motor 326 (L) d ), the quadrature axis inductance of motor 326 (L) q ) and the direct-axis current (i) at motor 326 q The function of ).

[0131] In other examples, controller 302 uses other estimation techniques to treat the motor's output torque as the quadrature-axis current (i). q ) and / or direct-axis current (i d The torque component 1304 can be estimated using this method. In various implementations, the motor torque component 1304 can be expressed as a value in Newton-meters (Nm).

[0132] The inertia component 1308 may represent the inertia of the motor 326 and / or the inertia of the transmission components between the motor 326 and the output element 116. In some examples, this may be relevant during startup. The controller 302 may calculate the inertia component 1308 as a function of the rotational speed (ω) of the motor 326. In various embodiments, the inertia component 1308 may be expressed as a value in kilograms per square meter (kg·m²).

[0133] In some implementations, the inertial component 1308 can be estimated by analyzing the acceleration behavior of the motor 326 in response to the applied torque. For example, when a substantially constant torque is applied to the motor 326, a linear increase in rotational speed (e.g., in RPM) can be observed. The slope of this increase can correspond to angular acceleration (α), which can be used to infer the system's moment of inertia (J), for example, according to the following equation (3): (3) In equation (3), T can represent the applied torque (e.g., in Nm), J can represent the moment of inertia (e.g., in kg·m²), and α can represent the angular acceleration (e.g., in rad / s²). 2 By monitoring the change of motor speed over time with a known torque component, controller 302 can estimate the effective inertia of the system and update the inertia component 1308 accordingly.

[0134] The drag component 1310 can represent the torque loss associated with the fan at motor 326. Controller 302 can calculate the drag component 1310 as a function of the rotational speed (ω) of motor 326. In various embodiments, the drag component 1310 can be expressed as a value in Newton-meters (Nm). In some embodiments, controller 302 can estimate the drag component 1310 by evaluating the steady-state operating conditions of motor 326. For example, when motor 326 operates at a constant speed (e.g., steady state), the applied motor torque can be balanced by an opposing load torque. Under no-load or low-load conditions, this opposing load torque may be primarily attributed to parasitic losses such as friction and drag. By operating motor 326 at multiple steady-state speeds and recording the corresponding torque required to maintain each speed, controller 302 can generate a model characterizing the relationship between rotational speed and drag / friction torque. This model can then be used to update the drag component 1310 and / or the friction component 1312.

[0135] The friction component 1312 can be attributed to torque loss caused by friction between the motor 326 and the output element 116. The controller 302 can calculate the friction component 1312 as a function of the rotational speed (ω) of the motor 326. In various embodiments, the friction component 1312 can be expressed as a value in Newton-meters (Nm).

[0136] The torque estimation model 1302 can determine the estimated output torque based on the motor torque component 1304 and the parasitic torque loss component 1306. In some examples, the controller 302 can subtract the parasitic torque loss component 1306 from the motor torque component 1304 to determine the estimated output torque.

[0137] In various implementations, the torque estimation model 1302 can be expressed according to equation (3): (3) As shown in equation (3), the motor torque f(i) can be estimated from the equation. q i d Subtract dynamic losses The estimated output torque (T) is determined by using the speed-related loss f(ω) and the speed-related loss f(ω). outputIn various implementations, dynamic loss The inertial component 1308 may be included, and the velocity-related loss f(ω) may include a drag component 1310 and / or a friction component 1312. In some embodiments, the estimated output torque is also compensated for by temperature (e.g., motor temperature, switching circuit temperature, ambient temperature, etc.).

[0138] Controller 302 can apply a filter to process the motor torque f(i) q i d The estimated values ​​of ω and rotational speed (ω) are used to reduce noise and harmonics. In various implementations, filters of the same type with identical parameters can be applied to both estimates to maintain consistency and prevent differences in signal timing.

[0139] If the motor torque f(i) q i d If the estimated values ​​of motor torque and speed (ω) are filtered differently, they may become misaligned. Filters can introduce phase shifts, which can cause the signal to be delayed by different amounts depending on the filter characteristics. In some examples, applying different filters to the estimates of motor torque and speed can cause time shifts between the signals, introducing errors in the control system.

[0140] Additionally, filters can be configured to have the same attenuation frequency. Filters can attenuate different frequency components at different rates. If the attenuation frequencies are different, some harmonic components may be removed from one estimate but not from another, leading to inconsistencies that can affect system performance.

[0141] The attenuation frequency of the filter can be selected to mitigate aliasing caused by ripple in torque and speed signals. Aliasing can occur when high-frequency components are not adequately filtered before sampling, resulting in spurious low-frequency variations. This effect can also occur if the sampling rate is too low to capture the full frequency content of the signal, leading to distorted or misleading data. In motor control applications, aliasing can introduce errors in torque estimation and cause unstable braking behavior. To reduce aliasing, the filter can be configured to remove high-frequency noise while retaining relevant signal information before sampling.

[0142] The attenuation frequency of the filter can also be set to suppress the sixth harmonic frequency of the control system. In various embodiments, the control system operates at approximately 1 kHz, so the filter can be configured to at least double the 6 kHz harmonic frequency. In some examples, the attenuation frequency is at least 12 kHz. In various embodiments, the filter operates at approximately 20 kHz. In some examples, the filter is implemented as a second-order Butterworth filter.

[0143] Back Figure 12 In example process 1200, controller 302 determines whether the estimated torque output meets or exceeds (e.g., surpasses) a threshold (decision box 1208). In various implementations, the threshold is set based on user input, such as selections made via torque selector 112 and / or range selector 114 as described above. If the estimated torque output meets or exceeds the threshold (yes at decision box 1208), controller 302 initiates braking of motor 326 (box 1210). Otherwise (no at decision box 1208), controller 302 continues to monitor the motor's current and speed (return to box 1202).

[0144] See also Figure 11 and Figure 12 The controller 302 can brake the motor by switching the power tool 100 to a braking state 1108. In the braking state 1108, the controller 302 can command various components of the power tool 100 to slow down or stop the motor 326.

[0145] In various implementations, controller 302 may command gate controller 322 to turn on all low-side switching elements of switching network 324. This configuration can create a low-impedance path for circulating current, dissipating energy through stator windings, and slowing the rotor. In some examples, controller 302 may alternatively command gate controller 322 to turn on all high-side switching elements, which can produce a similar braking effect with different current decay profiles.

[0146] In some implementations, braking may involve mechanical components. For example, controller 302 may actuate a friction brake that applies resistance to the motor shaft to slow rotation. In some examples, controller 302 may engage a mechanical clutch that disconnects the drivetrain to isolate torque transmission. Additionally, in various implementations, an electromagnetic brake may be used, in which controller 302 energizes a brake coil to generate resistance against the rotor.

[0147] Braking strategies can vary depending on factors such as motor type, operating conditions, and desired stopping characteristics. In various implementations, controller 302 can dynamically adjust braking intensity to balance stopping time, energy dissipation, and system stability.

[0148] After completing the braking operation in braking state 1108, controller 302 transitions power tool 100 to end indication state 1110. In end indication state 1110, controller 302 can command various components of power tool 100 to provide feedback indicating that the torque threshold has been reached and the electronic clutch has interrupted torque transmission.

[0149] In various implementations, controller 302 may generate motor jitter, wherein motor 326 oscillates or pulses briefly in response to a braking event. This can provide a tactile indication to the user that the electronic clutch has engaged. In some examples, controller 302 may activate one or more indicators 340 to convey this status visually, audibly, or tactilely. For example, controller 302 may illuminate an LED, generate an alarm sound, or trigger a tactile vibration.

[0150] In the end indication state 1110, if the controller 302 detects that the user has held the trigger 108 for more than a predetermined time threshold after completing the braking operation in the braking state 1108, the power tool 100 may transition to the continued driving state 1112. Otherwise, the power tool 100 transitions back to the idle state 1102.

[0151] In the continued drive state 1112, the controller 302 can intermittently apply torque to the output element 116 by briefly stimulating the motor 326 in a pulsed manner. In various embodiments, this can facilitate controlled incremental torque application, for example, for driving fasteners in small increments. In some examples, this feature can help the user apply additional torque beyond a threshold previously set by the electronic clutch.

[0152] When in continuous drive state 1112, controller 302 can suspend the electronic clutch function to allow uninterrupted torque transmission. In response to detecting that trigger 108 has been released, controller 302 switches power tool 100 back to idle state 1102.

[0153] Therefore, the embodiments described in this invention particularly provide an electric tool for implementing a field-oriented controlled electronic clutch. Various features and advantages are set forth in the appended claims.

Claims

1. An electric tool, comprising: electric motor; A first sensor, configured to monitor the electrical characteristics of the electric motor; Electronic controller, the electronic controller being configured as follows: At least one of the quadrature-axis current and direct-axis current of the electric motor is determined based on the sensor signal from the first sensor. Determine the rotational speed of the electric motor. The estimated torque output is determined based on at least one of (i) the quadrature-axis current and the direct-axis current and (ii) the rotational speed. In response to the estimated torque output exceeding a threshold, a command is output to brake the electric motor.

2. The power tool as claimed in claim 1, wherein, The electronic controller is further configured to determine the estimated torque output based on a torque estimation model, which includes a motor torque component and a parasitic loss component.

3. The power tool as claimed in claim 2, wherein, The electronic controller is further configured to determine the estimated torque output by subtracting the parasitic loss component from the motor torque component.

4. The power tool as claimed in claim 2, wherein, The electronic controller is further configured to determine an estimated motor torque based on the motor torque component, which is a function of at least one of the quadrature-axis current and the direct-axis current.

5. The power tool as claimed in claim 2, wherein, The electronic controller is further configured as follows: The quadrature-axis current and the direct-axis current of the electric motor are determined based on the sensor signals from the first sensor; and The estimated motor torque is determined based on the motor torque components, which are functions of the quadrature-axis current and the direct-axis current.

6. The power tool as claimed in claim 2, wherein, The electronic controller is further configured to determine an estimated parasitic torque loss based on the parasitic loss component, which is a function of the rotational speed.

7. The power tool as claimed in claim 2, wherein, The parasitic loss component includes at least one of the inertial component, wind resistance component, and friction component.

8. The power tool as claimed in claim 1, wherein, The electronic controller is further configured to determine the rotational speed of the electric motor based on sensor signals from the first sensor.

9. The power tool of claim 2, further comprising: A second sensor, configured to monitor the rotational characteristics of the electric motor; and The electronic controller is further configured to determine the rotational speed of the electric motor based on sensor signals from the second sensor.

10. A method comprising: At least one of the quadrature-axis current and direct-axis current of the electric motor of the power tool is determined based on sensor signals from a first sensor configured to monitor the electrical characteristics of the electric motor. Determine the rotational speed of the electric motor; The estimated torque output is determined based on at least one of (i) the quadrature axis current and the direct axis current and (ii) the rotational speed; and In response to the estimated torque output exceeding a threshold, a command is output to brake the electric motor.

11. The method according to claim 10, wherein, The estimated torque output is determined based on a torque estimation model, which includes a motor torque component and a parasitic loss component.

12. The method according to claim 11, wherein, Determining the estimated torque output includes subtracting the parasitic loss component from the motor torque component.

13. The method of claim 11, further comprising: The estimated motor torque is determined based on the motor torque component, which is a function of at least one of the quadrature-axis current and the direct-axis current.

14. The method of claim 11, further comprising: The quadrature-axis current and the direct-axis current of the electric motor are determined based on the sensor signal from the first sensor; and The estimated motor torque is determined based on the motor torque components, which are functions of the quadrature-axis current and the direct-axis current.

15. The method of claim 11, further comprising: The estimated parasitic torque loss is determined based on the parasitic loss component, which is a function of the rotational speed.

16. The method according to claim 11, wherein, The parasitic loss component includes at least one of the inertial component, wind resistance component, and friction component.

17. The method according to claim 11, wherein, The rotational speed of the electric motor is determined based on the sensor signal from the first sensor.

18. The method according to claim 11, wherein, The rotational speed of the electric motor is determined based on sensor signals from a second sensor configured to monitor the rotational characteristics of the electric motor.

19. A non-transitory computer-readable storage medium comprising executable instructions, said executable instructions causing the electronic processor, when executed by the electronic processor, to: At least one of the quadrature-axis current and direct-axis current of the electric motor of the power tool is determined based on sensor signals from a first sensor configured to monitor the electrical characteristics of the electric motor. Determine the rotational speed of the electric motor; The estimated torque output is determined based on at least one of (i) the quadrature axis current and the direct axis current and (ii) the rotational speed; and In response to the estimated torque output exceeding a threshold, a command is output to brake the electric motor.

20. The non-transitory computer-readable storage medium of claim 19, wherein, When the executable instructions are executed by the electronic processor, the electronic processor: The estimated torque output is determined based on a torque estimation model, which includes a motor torque component and a parasitic loss component.

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