CN116803620A - Electronic clutch for power tool - Google Patents

Electronic clutch for power tool Download PDF

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Publication number
CN116803620A
CN116803620A CN202310302829.6A CN202310302829A CN116803620A CN 116803620 A CN116803620 A CN 116803620A CN 202310302829 A CN202310302829 A CN 202310302829A CN 116803620 A CN116803620 A CN 116803620A
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CN
China
Prior art keywords
motor
torque
controller
rate
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN202310302829.6A
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Chinese (zh)
Inventor
A·加斯帕
R·基斯
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Milwaukee Electric Tool Corp
Original Assignee
Milwaukee Electric Tool Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Milwaukee Electric Tool Corp filed Critical Milwaukee Electric Tool Corp
Publication of CN116803620A publication Critical patent/CN116803620A/en
Pending legal-status Critical Current

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Classifications

    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B25—HAND TOOLS; PORTABLE POWER-DRIVEN TOOLS; MANIPULATORS
    • B25F—COMBINATION OR MULTI-PURPOSE TOOLS NOT OTHERWISE PROVIDED FOR; DETAILS OR COMPONENTS OF PORTABLE POWER-DRIVEN TOOLS NOT PARTICULARLY RELATED TO THE OPERATIONS PERFORMED AND NOT OTHERWISE PROVIDED FOR
    • B25F5/00—Details or components of portable power-driven tools not particularly related to the operations performed and not otherwise provided for
    • B25F5/001—Gearings, speed selectors, clutches or the like specially adapted for rotary tools

Abstract

Systems and methods for electronically limiting torque in a power tool are provided. A power tool includes a motor, a trigger, and a controller coupled to the trigger and the motor. The controller is configured to: providing power to the motor in response to actuation of the trigger; determining a rate of the motor; activating an electronic clutch to electronically brake the motor for a second period of time in response to determining that the rate of the motor has fallen by a rate-falling threshold within the first period of time; and providing power to the motor in response to the second period of time having elapsed.

Description

Electronic clutch for power tool
Cross Reference to Related Applications
The present application claims the benefit of U.S. provisional patent application No. 63/384,891 filed 11/23 at 2022 and U.S. provisional patent application No. 63/322,949 filed 3/23 at 2022, the disclosures of which are incorporated herein by reference in their entireties.
Disclosure of Invention
Embodiments described herein provide systems and methods for implementing an electronic clutch in a power tool.
The power tools described herein include an electronic clutch. The power tool includes a motor, a trigger, and a controller coupled to the trigger and the motor. The controller is configured to: providing power to the motor in response to actuation of the trigger; determining a rate of the motor; activating the electronic clutch to electronically brake the motor for a second period of time in response to determining that the rate of the motor has decreased by the rate-decrease threshold within the first period of time; and providing power to the motor in response to the second period of time having elapsed.
In some aspects, the controller is further configured to: determining a torque value to drive the motor based on the rate of the motor and the rate command signal; comparing the torque value to a torque-to-current look-up table; determining a current value provided to the motor based on the comparison; and providing the current value to the motor to drive the motor.
In some aspects, the power tool further comprises a current sensor configured to provide a current signal indicative of a current of the motor, and wherein the controller is further configured to: receiving the current signals from the current sensor indicative of the current of the motor; determining a Pulse Width Modulation (PWM) duty cycle based on the current of the motor and the current value; and driving the motor according to the PWM duty cycle.
In some aspects, the power tool includes a torque sensor configured to provide a torque signal indicative of a torque of the motor, and the controller is further configured to: receiving a torque signal from the torque sensor indicative of a torque of the motor; determining a Pulse Width Modulation (PWM) duty cycle based on the torque of the motor and the desired torque value; and driving the motor according to the PWM duty cycle.
In some aspects, the controller is further configured to control the motor according to the first mode of operation for a third period of time in response to actuation of the trigger.
In some aspects, the controller is further configured to limit motor current provided to the motor for a fourth period of time in response to the third period of time having elapsed.
In some aspects, the controller is further configured to control the motor according to the first mode of operation in response to the fourth period of time having elapsed.
In some aspects, the power tool further comprises an input device configured to set a desired torque value, and wherein the controller is further configured to: determining a torque limit based on the desired torque value; and controlling the motor based in part on the torque limit.
In some aspects, the input device is a torque ring.
In some aspects, the controller is configured to: detecting a high load condition of the motor based on a rate of the motor; and limiting a torque value driving the motor in response to a high load condition of the motor.
The method described herein for operating a power tool including an electronic clutch includes: providing power to the motor in response to actuation of the trigger; determining a rate of the motor; determining whether the rate of the motor has fallen by a rate-falling threshold within a first time period; activating the electronic clutch to electronically brake the motor for a second period of time in response to determining that the rate of the motor has decreased by the rate-decrease threshold within the first period of time; and providing power to the motor in response to the second period of time having elapsed.
In some aspects, the method further comprises: determining a torque value to drive the motor based on the rate of the motor and the rate command; comparing the torque value to a torque-to-current look-up table; determining a current value provided to the motor based on the comparison; and providing the current value to the motor to drive the motor.
In some aspects, the method further comprises: receiving a current signal from a current sensor indicative of a current of the motor; determining a Pulse Width Modulation (PWM) duty cycle based on the current of the motor and the current value; and driving the motor according to the PWM duty cycle.
In some aspects, the method further comprises: receiving a torque signal from a torque sensor indicative of a torque of the motor; determining a Pulse Width Modulation (PWM) duty cycle based on the torque of the motor and the desired torque value; and driving the motor according to the PWM duty cycle.
In some aspects, the method further comprises: controlling the motor for a third period of time according to a first mode of operation in response to actuation of the trigger; and limiting motor current provided to the motor for a fourth period of time in response to the third period of time having elapsed.
In some aspects, the method further comprises: determining a torque limit based on the desired torque value; and controlling the motor based in part on the torque limit.
In some aspects, the method further comprises: detecting a high load condition of the motor based on a rate of the motor; and limiting a torque value driving the motor in response to a high load condition of the motor.
In some aspects, the method further comprises: receiving a temperature signal from a temperature sensor indicative of a temperature of a mechanism driven by the motor; determining a torque value to drive the motor based on the temperature signals; and driving the motor according to the torque value.
The power tools described herein include an electronic clutch. The power tool includes a motor and a controller coupled to the motor. The controller is configured to: driving the motor according to a first rate setting; determining a rate of the motor; determining whether the speed of the motor is greater than or equal to a first speed threshold when at the first speed setting; driving the motor according to a second rate setting in response to the motor having a rate greater than or equal to the rate threshold; determining whether the speed of the motor is less than a second speed threshold when at the second speed setting; and limiting motor current for a clutch timeout period in response to determining that the rate of the motor is below the second rate threshold.
In some aspects, the controller is further configured to drive the motor according to the first rate setting in response to the clutch timeout period having elapsed.
In some aspects, the first rate threshold is equal to the second rate threshold.
In some aspects, the power tool further comprises an input device configured to set a desired torque value, and wherein the controller is further configured to: calculating a torque limit based on the desired torque value; and controlling the motor based in part on the torque limit.
The power tools described herein include an electronic clutch. The power tool includes: a motor, a mechanism coupled to the motor, a temperature sensor configured to provide a temperature signal indicative of a temperature of the mechanism, a trigger, and a controller connected to the trigger and the motor. The controller is configured to: providing power to the motor in response to actuation of the trigger; receiving a temperature signal from the temperature sensor indicative of the temperature of the mechanism; and determining a torque value to drive the motor based on the temperature signals.
The power tool described herein includes: a motor, a gear train coupled to the motor, a gear selector device configured to set a gear ratio of the gear train, a trigger, and a controller. The controller is connected to the motor, the trigger and the gear selector means. The controller is configured to: receiving an indication from the trigger to drive the motor; determining a torque setting for the power tool; determining a rate setting for the power tool; and controlling the gear selector device to set a gear ratio of the gear train based on the torque setting and the speed setting.
In some aspects, the gear selector apparatus includes a solenoid, a ferromagnetic guide ring, and a spring coupled to the ferromagnetic guide ring.
In some aspects, the controller is further configured to control the gear selector apparatus by providing current to the solenoid to generate a magnetic flux, and the magnetic flux provides a force on the ferromagnetic guide ring that is greater than and opposite to a force provided on the ferromagnetic guide ring by the spring.
In some aspects, the controller is further configured to: determining whether the torque setting of the power tool is within a low torque range; and controlling the gear selector means to set the gear ratio to a default gear ratio in response to the torque setting not being within the low torque range.
In some aspects, the controller is further configured to: determining whether the rate setting of the power tool is in a low speed mode; and controlling the gear selector means to set the gear ratio to the default gear ratio in response to the rate setting of the power tool being other than the low speed mode.
In some aspects, the controller is further configured to: in response to the torque setting of the power tool being within the low torque range and in response to the rate of the power tool being set to the low speed mode, the gear selector means is controlled to set the gear ratio to a second gear ratio different from the default gear ratio.
The methods described herein for operating a power tool include: receiving an indication of a drive motor from a trigger; determining a torque setting for the power tool; determining a rate setting for the power tool; and controlling a gear selector device to set a gear ratio of a gear train coupled to the motor based on the torque setting and the speed setting.
In some aspects, the method further comprises controlling the gear selector apparatus by providing current to a solenoid to generate a magnetic flux.
In some aspects, the method further comprises: determining whether the torque setting of the power tool is within a low torque range; and controlling the gear selector means to set the gear ratio to a default gear ratio in response to the torque setting not being within the low torque range.
In some aspects, the method further comprises: determining whether the rate setting of the power tool is in a low speed mode; and controlling the gear selector means to set the gear ratio to the default gear ratio in response to the rate setting of the power tool being other than the low speed mode.
In some aspects, the method further comprises: in response to the torque setting of the power tool being within the low torque range and in response to the rate of the power tool being set to the low speed mode, the gear selector means is controlled to set the gear ratio to a second gear ratio different from the default gear ratio.
The power tool described herein includes: a motor, a battery pack, a switching network connected between the motor and the battery pack and configured to provide power to the motor, a current sensor configured to sense a current of the motor, a trigger, and a controller connected to the switching network, the trigger, and the current sensor. The switching network includes a plurality of switches. The controller is configured to: driving the motor by controlling the plurality of switches at a first Pulse Width Modulation (PWM) frequency in response to actuation of the trigger; receiving a current signal from the current sensor indicative of a current of the motor; selecting a second PWM frequency based on the current signal; and driving the motor by controlling the plurality of switches at the second PWM frequency.
In some aspects, the power tool further comprises a position sensor configured to sense a position of the motor, and the controller is further configured to: receiving a position signal from the position sensor indicating a position of the motor; generating a noise signal based on the position of the motor; and injecting the noise signal into a voltage command signal, the noise signal being opposite in magnitude to natural noise generated by the motor.
In some aspects, to generate the noise signal, the controller is further configured to: comparing the torque of the motor and the angular velocity of the motor with a first lookup table to generate a first voltage magnitude and a first phase offset; summing the first phase offset with a first harmonic of a frequency of the motor-generated torque ripple to generate a first harmonic sum; and summing the first voltage magnitude with the first harmonic sum.
In some aspects, to generate the noise signal, the controller is further configured to: comparing the torque of the motor and the angular velocity of the motor with a second lookup table to generate a second voltage magnitude and a second phase offset; summing the second phase offset with a second harmonic of the frequency of the torque ripple generated by the motor to generate a second harmonic sum; and summing the second voltage magnitude with the second harmonic sum.
In some aspects, the controller is configured to select the second PWM signal by comparing the current signal to a table stored in memory.
In some aspects, the power tool further comprises a temperature sensor configured to sense temperatures of the plurality of switches, and the controller is further configured to: the method includes receiving a temperature signal from the temperature sensor indicating a temperature of the plurality of switches, adjusting the second PWM frequency based on the temperature signal to generate a third PWM frequency, and driving the motor by controlling the plurality of switches at the third PWM frequency.
The methods described herein for operating a power tool include: driving a motor by controlling a plurality of switches at a first Pulse Width Modulation (PWM) frequency in response to actuation of a trigger, wherein the plurality of switches are connected between the motor and a battery pack and configured to provide power to the motor; receiving a current signal from a current sensor indicative of a current of the motor; selecting a second PWM frequency based on the current signal; and driving the motor by controlling the plurality of switches at the second PWM frequency.
In some aspects, the method further comprises: receiving a position signal from a position sensor indicating a position of the motor; generating a noise signal based on the position of the motor; and injecting the noise signal into a voltage command signal, the noise signal being opposite in magnitude to natural noise generated by the motor.
In some aspects, generating the noise signal further comprises: comparing the torque of the motor and the angular velocity of the motor with a first lookup table to generate a first voltage magnitude and a first phase offset; summing the first phase offset with a first harmonic of a frequency of the motor-generated torque ripple to generate a first harmonic sum; and summing the first voltage magnitude with the first harmonic sum.
In some aspects, generating the noise signal comprises: comparing the torque of the motor and the angular velocity of the motor with a second lookup table to generate a second voltage magnitude and a second phase offset; summing the second phase offset with a second harmonic of the frequency of the torque ripple generated by the motor to generate a second harmonic sum; and summing the second voltage magnitude with the second harmonic sum.
In some aspects, selecting the second PWM frequency includes comparing the current signal to a table.
In some aspects, the method further comprises: the method includes receiving a temperature signal from the temperature sensor indicating a temperature of the plurality of switches, adjusting the second PWM frequency based on the temperature signal to generate a third PWM frequency, and driving the motor by controlling the plurality of switches at the third PWM frequency.
Before any embodiments are explained in detail, it is to be understood that the embodiments are not limited in their application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The embodiments may be practiced or carried out in a variety of different ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of "including," "comprising," or "having" and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless specified or limited otherwise, the terms "mounted," "connected," "supported," and "coupled" and variations thereof are used broadly and encompass both direct and indirect mountings, connections, supports, and couplings.
In addition, it should be understood that embodiments may include hardware, software, and electronic components or modules that, for purposes of discussion, may be shown and described as if most of the components were implemented solely in hardware. However, one of ordinary skill in the art will recognize, based on a reading of this detailed description, that in at least one embodiment, the electronic-based aspects may be implemented in software (e.g., stored on a non-transitory computer-readable medium) executable by one or more processing units (e.g., a microprocessor and/or an application specific integrated circuit ("ASIC")). Thus, it should be noted that embodiments may be implemented using a number of hardware and software based devices as well as a number of different structural components. For example, the "servers" and "computing devices" described in this specification may include one or more processing units, one or more computer-readable medium modules, one or more input/output interfaces, and various connections (e.g., a system bus) to components.
Other features and aspects will become apparent by consideration of the following detailed description and accompanying drawings.
Drawings
Fig. 1 illustrates a power tool according to embodiments described herein.
FIG. 2 illustrates a block diagram of a controller of the power tool of FIG. 1, according to embodiments described herein.
Fig. 3 illustrates a block diagram of a control architecture implemented by the controller of fig. 2, according to embodiments described herein.
Fig. 4 illustrates a block diagram of a control block included in the control architecture of fig. 3, according to an embodiment described herein.
FIG. 5 illustrates a block diagram of another control block included in the control architecture of FIG. 3, according to an embodiment described herein.
Fig. 6A-6B illustrate graphs for measuring absorbed energy of a motor according to embodiments described herein.
Fig. 7 illustrates a state machine block diagram of an electronic clutch according to embodiments described herein.
Fig. 8 illustrates a block diagram of a rate controller according to embodiments described herein.
FIG. 9 illustrates a block diagram of a lookup table operation in accordance with an embodiment described herein.
Fig. 10 illustrates a block diagram of a bus current controller according to embodiments described herein.
Fig. 11 illustrates a block diagram of a method performed by the controller of fig. 2, according to embodiments described herein.
Fig. 12A-12B illustrate block diagrams of another method performed by the controller of fig. 2, according to embodiments described herein.
FIG. 13 illustrates a graph of motor flywheel energy versus percent rated speed of a motor according to embodiments described herein.
Fig. 14A-14B illustrate cross-sections of the power tool of fig. 1 according to embodiments described herein.
Fig. 15A-15B illustrate side views of a gear selection apparatus according to embodiments described herein.
Fig. 16 illustrates a block diagram of another method performed by the controller of fig. 2, according to embodiments described herein.
Fig. 17 illustrates an open loop control diagram performed by the controller of fig. 2, according to embodiments described herein.
Fig. 18 shows a graph of average loss per FET versus bus current and switching frequency values, according to embodiments described herein.
Fig. 19 shows another plot of average loss per FET versus bus current and switching frequency values in accordance with embodiments described herein.
Fig. 20 illustrates a block diagram of another method performed by the controller of fig. 2, according to embodiments described herein.
Detailed Description
FIG. 1 illustrates an example power tool 100 including an electronic clutch, according to some embodiments. The power tool 100 includes a housing 105, a battery pack interface 110, a driver 115 (e.g., a chuck or bit holder), a motor housing 120, a trigger 125, a handle 130, and an input device 140. The motor housing 120 accommodates a motor 280 (see fig. 2). A longitudinal axis 135 extends from the driver 115 through the rear of the motor housing 120. In operation, the driver 115 rotates about the longitudinal axis 135. The longitudinal axis 135 may be substantially perpendicular to the handle 130. While fig. 1 illustrates a particular power tool 100 having a rotational output, it is contemplated that the electronic clutch described herein may be used with a variety of types of power tools, such as a drill bit, a driver, a power screwdriver, a power ratchet, a grinder, a right angle drill, a rotary hammer, a pipe threading machine, or another type of power tool that is subject to rotation about an axis (e.g., longitudinal axis 135). In some embodiments, the power tool 100 is a power tool that undergoes translational movement along a longitudinal axis 135, such as a reciprocating saw, chain saw, long handle saw, circular saw, cutting saw, die grinder, and table saw.
A controller 200 for the power tool 100 is shown in fig. 2. The controller 200 is electrically and/or communicatively connected to various modules or components of the power tool 100. For example, the illustrated controller 200 is connected to an indicator 245, a current sensor 270, a rate sensor 250, a temperature sensor 272, auxiliary sensor(s) 274 (e.g., voltage sensor, accelerator, torque sensor or torque transducer, etc.), a trigger 125 (connected via a trigger switch 158), a power switching network 255, and a power input unit 260.
The controller 200 includes a plurality of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller 200 and/or the power tool 100. For example, the controller 200 includes, among other things, a processing unit 205 (e.g., a microprocessor, electronic processor, electronic controller, microcontroller, or other suitable programmable device), a memory 225, an input unit 230, and an output unit 235. The processing unit 205 includes, among other things, a control unit 210, an arithmetic logic unit ("ALU") 215, and a plurality of registers 220 (shown as a set of registers in fig. 2), and is implemented using a known computer architecture, such as a modified harvard architecture (Harvard architecture), a von neumann architecture (von Neumann architecture), or the like. The processing unit 205, memory 225, input unit 230, and output unit 235, as well as the various modules connected to the controller 200, are connected by one or more control and/or data buses (e.g., a common bus 240). For illustrative purposes, a control bus and/or a data bus is generally shown in FIG. 2. The use of one or more controls and/or data buses for interconnection and communication between various modules and components will be known to those skilled in the art in view of the embodiments described herein.
Memory 225 is a non-transitory computer readable medium and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area may comprise a combination of different types of memory, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, hard disk, SD card, or other suitable magnetic, optical, physical, or electronic memory device. The processing unit 205 is connected to a memory 225 and executes software instructions that can be stored in a RAM of the memory 225 (e.g., during execution), a ROM of the memory 225 (e.g., on a generally permanent basis), or another non-transitory computer readable medium such as another memory or disk. Software included in an embodiment of the power tool 100 may be stored in the memory 225 of the controller 200. The software includes, for example, firmware, one or more application programs, program data, filters, rules, one or more program modules, and other executable instructions. The controller 200 is configured to retrieve from the memory 225 and execute, among other things, instructions related to the control processes and methods described herein. In other embodiments, the controller 200 includes additional, fewer, or different components.
The controller 200 drives the motor 280 to rotate the driver 115 in response to user actuation of the trigger 125. The drive 115 may be coupled to a motor 280 via an output shaft 1400 (shown in fig. 14A and 14B). Depressing the trigger 125 actuates the trigger switch 158, which outputs a signal to the controller 200 to drive the motor 280, and thus the driver 115. In some embodiments, the controller 200 controls the power switching network 255 (e.g., FET switching bridge) to drive the motor 280. For example, the power switching network 255 may include a plurality of high-side switching elements (e.g., FETs) and a plurality of low-side switching elements. The controller 200 may control each FET of the plurality of high-side switching elements and the plurality of low-side switching elements to drive each phase of the motor 280. For example, the power switching network 255 may be controlled to slow down the motor 280 faster. In some embodiments, the controller 200 monitors the rotation of the motor 280 (e.g., the rotational speed of the motor 280, the position of the motor 280, etc.) via the rate sensor 250. The motor 280 may be configured to drive a gearbox 285 (e.g., a mechanism). In some embodiments, the controller 200 is configured to set the gear ratio of the gears within the gearbox 285, as described in more detail below.
The indicator 245 is also connected to the controller 200 and receives control signals from the controller 200 to turn on and off or otherwise communicate information based on the different states of the power tool 100. The indicator 245 includes, for example, one or more Light Emitting Diodes (LEDs), or a display screen. The indicator 245 may be configured to display a condition of the power tool 100 or information related to the power tool. For example, the indicator 245 may display information related to the operational status (such as mode or rate setting) of the power tool 100. The indicator 245 may also display information related to a fault condition or other anomaly of the power tool 100. In addition to or in lieu of the visual indicator, the indicator 245 may also include a speaker or a tactile feedback mechanism to convey information to the user through an audible or tactile output. In some embodiments, the indicator 245 displays information related to a braking operation or a clutching operation (e.g., an electronic clutching operation) of the controller 200. For example, one or more LEDs are activated when the controller 200 is performing a clutching operation. In some embodiments, the indicator 245 displays information related to the selected gear ratio of the gearbox 285.
The battery pack interface 110 is connected to the controller 200 and is configured to couple with the battery pack 150. The battery pack interface 110 includes a combination of mechanical components (e.g., a battery pack receiving portion) and electrical components configured and operable to interface (e.g., mechanically, electrically, and communicatively connect) the power tool 100 with the battery pack 150. The battery pack interface 110 is coupled to the power input unit 260. The battery pack interface 110 transmits power received from the battery pack 150 to the power input unit 260. The power input unit 260 includes active and/or passive components (e.g., buck controllers, voltage converters, rectifiers, filters, etc.) to regulate or control the power received through the battery pack interface 110 that is provided to the controller 200. In some embodiments, the battery pack interface 110 is also coupled to a power switch network 255. The operation of the power switching network 255 controlled by the controller 200 determines how power is supplied to the motor 280.
The current sensor 270 senses the current provided by the battery pack 150, the current associated with the motor 280, or a combination thereof. In some embodiments, current sensor 270 senses at least one of the phase currents of the motor. The current sensor 270 may be, for example, an in-line phase current sensor, a pulse width modulated center sampling inverter bus current sensor, or the like. The speed sensor 250 senses the speed of the motor 280. The rate sensor 250 may include, for example, one or more hall effect sensors. In some embodiments, the temperature sensor 272 senses the temperature of the switching network 255, the battery pack 150, the motor 280, the gearbox 285, or a combination thereof. The input device 140 is operably coupled to the controller 200 to, for example, select a forward mode of operation, a reverse mode of operation, a torque setting for the power tool 100, a gear ratio of the gearbox 285, and/or a speed setting (e.g., using torque and/or speed switches) for the power tool 100, etc. In some embodiments, the input device 140 includes a combination of digital and analog input or output devices, such as one or more knobs, one or more dials, one or more switches, one or more buttons, etc., as needed to achieve a desired level of operation of the power tool 100. In other embodiments, the input device 140 is configured as a ring (e.g., a torque ring). Movement of the input device 140 sets a desired torque and/or desired speed value for the drive motor 280.
Motor and electronic clutch control
The controller 200 is configured to monitor an operating characteristic of the power tool 100 to drive the motor 280. For example, fig. 3 provides a block diagram of a control architecture 300 implemented by the controller 200. The control architecture 300 includes, among other things, a speed estimator module 302, a temperature reader module 304, a current reader module 306, a Pulse Width Modulation (PWM) limiter 308, a field weakening module 322, a dynamic commutation module 324, and a driving algorithm 310. The drive algorithm 310 includes, among other things, software and applications for driving the motor 280, such as a rate controller 312, a torque limiter module 314, a brake control module 316, a look-up table 318, and a bus current controller 320. The control architecture 300 of fig. 3 is merely an example. In other embodiments, the functions of the various modules and controllers may be combined together or separated into additional modules.
The speed estimator module 302 receives a speed signal from the speed sensor 250 indicative of the speed or speed of the motor 280. The velocity estimator module 302 converts the received velocity signal to a velocity value or velocity value, which is then provided to the drive algorithm 310. In some embodiments, the rate signal from rate sensor 250 is provided directly to drive algorithm 310.
In some embodiments, the speed estimator module 302 determines (or estimates) the speed or velocity of the motor 280 based on the current signal from the current sensor 270. For example, the speed estimator module 302 converts the received current signal to a speed value or speed value, which is then provided to the drive algorithm 310. In some embodiments, the speed estimator module 302 determines a speed or velocity of the motor 280 based on a voltage of the motor 280 (as received from a voltage sensor included in the auxiliary sensor 274).
The temperature reader module 304 receives a temperature signal from the temperature sensor 272 that is indicative of the temperature of the power tool 100. For example, the temperature reader module 304 receives a temperature signal indicative of the temperature of the gearbox 285. In some embodiments, temperature reader module 304 receives a temperature signal indicative of the temperature of motor 280 and/or switch network 255. The temperature reader module 304 converts the temperature signal to a temperature value, which is then provided to the drive algorithm 310. The drive algorithm 310 then selects a torque value for the drive motor 280 based on the temperature value. In some embodiments, the temperature signal from the temperature sensor 272 is provided directly to the drive algorithm 310. The temperature signal may be used by the driving algorithm 310 to improve torque repeatability over a wide temperature range.
The current reader module 306 receives a current signal from the current sensor 270 indicative of the current of the motor 280. The current reader module 306 converts the received current signal into a current value (e.g., a voltage indicative of current) that is then provided to the drive algorithm 310. In some embodiments, the current signal from current sensor 270 is provided directly to drive algorithm 310.
The PWM limiter 308 receives the current of the motor 280 from the current reader module 306. PWM limiter 308 limits the maximum PWM ratio command for driving motor 280 to prevent a low voltage condition from occurring on switching network 255 (e.g., gate driver). The PWM ratio command limits are provided to the bus current controller 320.
The embodiments described herein primarily refer to bus current controller 320 receiving a current signal from current reader module 306. However, in some cases, the control architecture 300 may reference direct torque measurements rather than current measurements. For example, the control architecture 300 may include a torque reader module that receives torque signals from torque sensors (e.g., torque transducers) included in the auxiliary sensor(s) 274. The torque signal indicates the torque of the motor 280 and/or the output torque of the power tool. The torque reader module converts the received torque signal to a torque value (e.g., a voltage indicative of torque), which is then provided to the drive algorithm 310. In addition, the PWM limiter 308 receives the torque value from the torque reader module. The PWM limiter 308 limits the maximum PWM ratio command for driving the motor 280 based on the torque value from the torque reader module. The PWM ratio command limits are provided to a bus current controller 320 (which may alternatively be referred to as a torque controller in this case).
Fig. 4 provides a block diagram of a control block 400 for controlling the motor 280. The speed controller 312 receives the motor speed or speed from the speed estimator module 302. In addition, the rate controller 312 receives a rate command. For example, the distance that the trigger 125 is actuated may be associated with a desired rate of the motor 280, and a corresponding rate command signal is generated. In such an example, the controller 200 translates the distance that the trigger 125 is actuated into a rate command for controlling the motor 280. The speed controller 312 compares the motor speed provided by the speed estimator module 302 to the speed command to determine the torque to drive the motor 280. For example, if the motor speed is less than the speed command, the speed controller 312 outputs a torque command (torque value) to increase the speed of the motor 280. If the motor speed is greater than the speed command, the speed controller 312 outputs a torque command to reduce the speed of the motor 280. If the motor speed is equal to the speed command, the speed controller 312 outputs a torque command to maintain the speed of the motor 280.
The torque command and motor rate are provided to a lookup table 318. The torque command and motor speed are compared to a lookup table 318 (e.g., torque-to-current lookup table, torque-to-speed-to-current lookup table, speed-to-current lookup table) to determine a current command, such as a current value or bus current value, to drive the motor 280. The current command is the current required to produce the desired torque. The current command may be determined using the torque command and the motor speed. The current command is provided to bus current controller 320. The bus current controller 320 then compares the current command with a measured bus current (e.g., a measured current of the motor 280 provided by the current reader module 306). Based on this comparison, bus current controller 320 drives switching network 255 with a PWM ratio command (e.g., PWM duty cycle command). For example, if the current command is less than the measured bus current, the bus current controller 320 decreases the PWM duty cycle of the drive switch network 255. If the current command is greater than the measured bus current, the bus current controller 320 increases the PWM duty cycle driving the switching network 255. If the current command is equal to the measured bus current, the bus current controller 320 maintains the PWM duty cycle driving the switching network 255.
In some embodiments, the torque limiter module 314 limits the torque command provided by the rate controller 312. FIG. 5 provides a block diagram of a control block 500 for limiting torque commands. The torque set point is provided to the torque limiter module 314. For example, the torque set point may be provided by the input device 140.
The torque limiter module 314 limits torque based on, for example, the estimated absorbed energy of the motor 280. The energy absorption is estimated based on the principle of balancing the mechanical flywheel energy of the motor 280 and gearbox 285 with the available energy absorption of the driven fastener when it comes into engagement (e.g., in place). In one example, the motor torque remains constant at the beginning of engagement because the controller 200 actively controls the current at a high bandwidth.
The absorbed energy of the fastener is the integral of torque versus angle, and the net absorbed energy of the fastener is the absorbed energy minus the energy delivered by the torque of the motor 280. Fig. 6A provides an example of the absorbed energy when the motor torque remains constant after engagement. Equation 1 provides the absorbed energy in balance with the flywheel energy:
wherein:
j-bit reflection inertia from motor point of view (kg-m) 2 )
Omega-motor speed (rad/s)
T s -torque setpoint (Nm)
T d -driving torque or loading torque (Nm)
k Joining of -joint stiffness (Nm/rad)
When the torque limit is set to the drive torque, equation 1 may be rearranged such that the torque limit is set based on the motor speed, the torque set point, the bit inertia, and the engagement stiffness, as shown in equation 2:
wherein:
T limiting -torque limitation (Nm)
In another example, all of the absorbed energy of the fastener engagement is used to stop the motor 280. Thus, at the moment engagement is achieved, motor 280 is de-energized and a negative torque is introduced when the brake is applied. Fig. 6B provides an example of the energy absorbed when the motor 280 is de-energized. Equation 3 provides the absorbed energy in balance with the flywheel energy.
When the torque limit is set to the drive torque, equation 3 may be rearranged such that the torque limit is set based on the motor speed, the torque set point, the bit inertia, and the engagement stiffness, as shown in equation 4:
returning to FIG. 3, if the torque command is greater than the torque limit, the torque limit is instead provided to the lookup table 318. The torque limit is then continued to be used as a torque command to control the motor 280, as shown in FIG. 5.
In some embodiments, the PWM ratio commands provided by the bus current controller 320 are overridden by the brake control module 316. For example, based on the motor rate provided by the speed estimator module 302, the brake control module 316 can determine to brake the motor 280. Fig. 7 provides a state diagram 700 that illustrates the operation of the power tool 100 performed by the controller 200.
When the rate command for motor 280 is set to 0 (e.g., when trigger 125 is not actuated), controller 200 is in idle mode (block 710). While in idle mode, the controller 200 monitors the actuation of the trigger 125 and the switching network 255 is placed in a high impedance state to prevent power transfer from the battery pack 150 to the motor 280. When trigger 125 is actuated (e.g., rate command greater than 0), controller 200 determines whether power tool 100 is in a drill mode. While in the drill mode, the controller 200 proceeds to block 705. In the drill mode, the speed of the motor 280 is controlled at the maximum torque limit of the motor 280. The maximum torque limit of the motor 280 may be stored, for example, in the memory 225, set by the input device 140, etc. The drilling mode may be set, for example, by an input device 140 on the power tool 100. In some embodiments, the torque limiter module 314 is disabled when in the drill mode.
When the power tool 100 is not in the drill mode and the trigger 125 is actuated, the controller 200 proceeds to block 715 and operates the motor 280 according to the low speed mode (e.g., first mode of operation, first rate setting). The low speed mode may be, for example, an operating mode associated with starting to drive the motor 280 when the motor 280 is completely stopped. While in the low speed mode, the controller 200 monitors the speed of the motor 280 provided by the speed estimator module 302. In some embodiments, when in the low speed mode, the speed controller 312 is bypassed and the motor 280 is controlled such that the torque output of the speed controller 312 is equal to the torque set point. If the speed of motor 280 increases to greater than or equal to the minimum speed threshold, controller 200 proceeds to block 720. In some embodiments, the minimum rate threshold value is between 500 revolutions per minute ("500 RPM") and 3000 RPM. In some embodiments, the minimum rate threshold has a value of approximately 1800RPM. However, if the speed of the motor 280 remains below the minimum speed threshold for a low speed timeout period (e.g., a first predetermined period of time), the controller 200 instead proceeds to block 725. If the rate command is set to zero (0) at any point in time (e.g., when trigger 125 is deactivated), then controller 200 transitions back to idle mode (block 710).
When the speed of the motor 280 exceeds or equals the minimum speed threshold, the controller 200 proceeds to block 720 and operates in a high speed mode (e.g., a second mode of operation, a second speed setting). When in the high speed mode, the controller 200 drives the motor 280 within the set torque limit according to the received speed command. The rate controller 312 is active and the torque limiter module 314 may limit the torque output of the rate controller 312, which may reduce the rate set for the clutch or when significant loads are applied. For example, when a high load condition is detected based on the speed of motor 280, the torque output of speed controller 312 is limited.
When the speed of the motor 280 drops below the minimum speed threshold while operating in the high speed mode, the controller 200 proceeds to block 725 and operates in the clutch mode. In some embodiments, hysteresis may be used such that different rate thresholds are used to control transitions from low-speed mode to high-speed mode and transitions from high-speed mode to clutch mode. In addition, when the controller 200 is operating in the low speed mode (block 715) for a predetermined period of time, the controller 200 proceeds to block 725 and operates in the clutch mode. When in clutch mode, the controller 200 limits the current to the motor 280. For example, the current command provided to the bus current controller 320 by the lookup table 318 is overwritten with a low current command. In some embodiments, the low current command corresponds to a current value low enough to maintain engagement of the motor 280 with the gear train but not overcome gear train friction. This results in the torque value of the driver 115 being zero and simulates the sound that a mechanical clutch makes when engaged (e.g., the ratcheting sound caused by switching between the low speed mode and the clutch mode). The low current command is maintained for the clutch timeout period, at which point the controller 200 returns to block 715 and operates in the low speed mode. If trigger 125 is deactivated while controller 200 is in the clutch mode, controller 200 returns to block 710 and operates in the idle mode. Additionally, in some cases, due to the clutch timeout period and the low speed timeout period, the controller 200 may infinitely alternate (i.e., ratchet) between the low speed mode of block 715 and the clutch mode of block 725 until the trigger 125 is deactivated. In some embodiments, the values of the clutch timeout period and the low speed timeout period are between 5 milliseconds and 100 milliseconds. In some embodiments, the clutch timeout period and the low speed timeout period have values of approximately 35 milliseconds.
Returning to fig. 3, the field weakening module 322 is configured to increase torque capability at high speeds when the back electromotive force ("EMF") of the motor 280 causes the drive to become voltage limited. Field weakening can be applied by identifying the relationship between motor current, motor torque and motor speed in steady state. This relationship can be used to correct for nominal field weakening. In some embodiments, field weakening module 322 is disabled.
Fig. 8 illustrates an example block diagram of rate controller 312. Equation 5 provides an example model for determining a torque command based on motor speed:
equation 6 provides a simplified transfer function for the model of equation 5:
whenever the controller 200 is operating in the low speed mode, the torque command output by the rate controller 312 is locked to the upper torque limit. When the controller 200 is in clutch mode, the torque command is overridden downstream. However, the speedThe rate controller 312 continues to operate. The illustrated rate controller 312 includes two gains: proportional gain K P And integral gain K I 。
Fig. 9 illustrates an example block diagram of the lookup table 318. At the torque look-up table 900, the torque command from the rate controller 312 is compared to the motor rate. Torque lookup table 900 (e.g., a torque-speed-current lookup table) outputs a baseline bus current command. In addition, at the temperature lookup table 950, the motor rate is compared to the measured temperature provided by the temperature reader module 304. The output of the temperature look-up table 950 is a temperature adjustment output. The temperature adjustment output is applied to the baseline bus current command to create a bus current command that is provided to the bus current controller 320.
In some embodiments, rather than using the lookup table 318, a slope intercept method is used to convert the torque command to a bus current command. The slope intercept method converts torque to current independent of motor speed and temperature. For a given gear ratio, a slope and intercept are provided to convert torque to a current command.
Fig. 10 illustrates an example block diagram of a bus current controller 320. The bus current controller 320 outputs a PWM ratio command signal based on the bus current command from the lookup table 318. Equation 7 provides an example model for determining PWM ratio command signals based on bus current:
if the speed is constant with respect to the electrodynamics and the battery voltage is constant, the model of equation 7 becomes a transfer function defined by equation 8:
when the controller 200 operates in the low speed mode, the high speed mode, or the drill mode, the bus current controller 320 operates normally. When in idle mode or when braking, PWM ratioThe rate command output is overwritten to zero. In clutch mode, the bus current command is overwritten with another value to overcome cogging torque and reduce system backlash. Additionally, in some embodiments, the PWM ratio command is overridden with a value that increases the drill hole impingement when transitioning from clutch mode to low speed mode to improve the end of drill hole indication user experience. In addition, the bus current controller 320 may limit the PWM ratio command output to prevent bus current overshoot (e.g., an over-current condition). The bus current controller 320 is shown to include two gains: proportional gain K P And integral gain K I 。
Fig. 11 provides a method 1100 for controlling the motor 280. The method 1100 may be performed by the controller 200. At block 1105, the controller 200 sets the drive motor 280 according to a first rate. For example, the controller 200 drives the motor 280 according to a high-speed mode while receiving a rate command from the trigger 125. At block 1110, the controller 200 determines the rate of the motor 280. For example, in some embodiments, the controller 200 receives a rate signal from the rate sensor 250 that indicates the rate of the motor 280. In other embodiments, the controller 200 determines the rate of the motor 280 based on the current signal from the current sensor 270.
At block 1115, the controller 200 determines whether the rate of change of the motor 280 is greater than or equal to a rate reduction threshold (e.g., rate of change threshold, rate loss threshold, rate reduction threshold, etc.). If the rate of change of the motor 280 is less than the rate-decrease threshold, the controller 200 returns to block 1105 and continues to drive the motor 280 according to the first rate setting. For example, the speed of motor 280 undergoes a slight speed change. If the rate of change of the rate of the motor 280 is greater than or equal to the rate threshold (e.g., the rate decreases by 400 to 600RPM over a period of 10 ms), the controller 200 proceeds to block 1120. In some embodiments, the rate-reduction threshold corresponds to a revolution per minute ("RPM") change between 100RPM and 2000RPM during the first period of time. In some embodiments, the rate-reduction threshold corresponds to an RPM change of approximately 400RPM during the first period of time. In some embodiments, the controller 200 monitors the rate of the motor 280 over a first period of time (e.g., between 5 milliseconds and 100 milliseconds) to determine the rate of change. In some embodiments, the first period of time is approximately 10 milliseconds.
At block 1120, the controller 200 determines whether braking of the motor 280 is allowed. For example, to prevent false braking triggers, braking of motor 280 may be disabled for a predetermined period of time after the braking event is completed because braking slows the motor, which again may produce a rate reduction that meets the rate reduction threshold. By disabling the repeatedly occurring braking event, the controller 200 avoids an erroneous braking event. If a braking event is disabled, the controller 200 returns to block 1105 and continues to set the drive motor 280 according to the first rate. If a braking event is allowed, the controller 200 proceeds to block 1125. In some embodiments, the braking event is not disabled, and block 1120 (and blocks 1130 and 1135) may be removed from method 1100.
At block 1125, the controller 200 brakes the motor 280 for a predetermined period of time. For example, the controller 200 controls the switching network 255 to electronically brake the motor 280. Once the predetermined period of time is met, the controller 200 disables the braking event (at block 1130) and returns to block 1105. The controller 200 disables the braking event for a second predetermined period of time to prevent false braking triggers. Once the second predetermined period of time is met, the controller 200 allows a braking event to be performed (at block 1135). In some embodiments, braking is disabled at low speeds (e.g., 2000RPM or less).
Fig. 12A-12B provide a method 1200 for controlling a motor 280. The method 1200 may be performed by the controller 200. Method 1200 may be performed in parallel with method 1100 of fig. 11. At block 1205, the controller 200 sets the drive motor 280 according to the first rate. For example, the controller 200 drives the motor 280 according to the low speed mode while receiving a rate command from the trigger 125. At block 1210, the controller 200 determines the rate of the motor 280. For example, in some embodiments, the controller 200 receives a rate signal from the rate sensor 250 that indicates the rate of the motor 280. In other embodiments, the controller 200 determines the rate of the motor 280 based on the current signal from the current sensor 270.
At block 1215, the controller 200 determines whether the speed of the motor 280 is greater than or equal to a speed threshold. If the speed of motor 280 is greater than or equal to the speed threshold, controller 200 proceeds to block 1235 (see FIG. 12B). If the speed of motor 280 is less than the speed threshold, controller 200 determines if the low speed timeout threshold has been met (block 1220). If the low speed timeout threshold is not met, the controller 200 returns to block 1205 and continues to set the drive motor 280 according to the first rate.
If the low speed timeout threshold is met, the controller 200 proceeds to block 1225 and enters the electronic clutch mode. In the electronic clutch mode, the controller 200 drives the motor 280 according to the low current command, as previously described. At block 1230, the controller 200 determines whether a clutch timeout period is met. If the clutch timeout period is met, the controller 200 returns to block 1205 and sets the drive motor 280 according to the first rate. If the clutch timeout period is not met, the controller 200 returns to block 1225 and continues to operate in the electronic clutch mode. In some embodiments, the clutch timeout period corresponds to between 10 and 100 milliseconds. In some embodiments, the clutch timeout period is approximately 35 milliseconds.
Returning to block 1215, if the rate of the motor increases to greater than or equal to the rate threshold, the controller 200 proceeds to block 1235. At block 1235, the controller 200 sets the drive motor 280 according to the second rate. In some embodiments, the second rate setting is a high speed mode. At block 1240, the controller 200 determines the rate of the motor 280. For example, in some embodiments, the controller 200 receives a rate signal from the rate sensor 250 that indicates the rate of the motor 280. In other embodiments, the controller 200 determines the rate of the motor 280 based on the current signal from the current sensor 270.
At block 1245, the controller 200 determines whether the speed of the motor 280 is less than or equal to a speed threshold. If the speed of the motor 280 is greater than the speed threshold, the controller 200 continues to set the drive motor 280 according to the second speed. If the speed of motor 280 is less than or equal to the speed threshold, controller 200 proceeds to block 1225 and enters the electronic clutch mode. For example, the method 1100 in fig. 11 may cause a rapid deceleration of the motor 280, which causes the motor speed to become less than the speed threshold and transition from the second speed setting to the electronic clutch mode.
Ratio control
The flywheel energy of the motor 280 (such as described with respect to and shown in fig. 6A) depends on the speed of the motor 280. For example, fig. 13 provides a graph showing flywheel energy (in joules) versus the percent rated rate of motor 280. When in the low speed setting, the drive 115 rotates at approximately 500RPM and the motor rotates at 100% of rated speed. The flywheel energy produced was approximately 37 joules. However, when in the high speed setting, the drive rotates at approximately 500RPM and the motor rotates at approximately 28% of rated speed, producing approximately 3 joules of flywheel energy.
When the drive is hard-engaged, flywheel energy is transferred to the workpiece and motor 280 stops rotating, as shown in fig. 6A. Higher flywheel energy means that more energy is directed to the workpiece, which can result in torque overshoots if the rate is not limited. In the high speed mode, the rate output may be higher with less torque overshoot, thereby shortening the tightening time and improving torque accuracy for more sensitive applications.
To reduce flywheel energy and reduce torque overshoot, the controller 200 may automatically select the gear ratio of the gearbox 285 based on settings of the electronic clutch, such as the rate setting (or rate limiting) of the rate controller 312 and the torque setting (or torque limiting) of the torque limiter module 314. Specifically, the controller 200 may be configured to select a high gear ratio setting of the gearbox 285 in low torque applications.
To select the gear ratio of the gearbox 285, the power tool 100 is provided with an electronically selectable gear ratio. Fig. 14A and 14B illustrate a cross section of a motor housing 120 of the power tool 100 according to one embodiment. The motor housing 120 includes a motor 280 and a gear box 285. As previously described, rotation of the motor 280 rotates the gears within the gearbox 285. Rotation of the gear box 285 rotates an output shaft 1400 connected to the driver 115.
A gear selector device is disposed adjacent to the gearbox 285 to actuate gears within the gearbox 285 to set a gear ratio. Specifically, in the example of fig. 14A and 14B, the gear selector device 1405 is disposed substantially adjacent to the gear case 285. In some embodiments, the gear selector apparatus 1405 is a circular gear selector apparatus that provides a pushing and/or pulling force around the entire circumference of the gearbox 285. Although a single gear selector device 1405 is illustrated, in other embodiments, the power tool 100 may include two gear selector devices or three or more gear selector devices.
The gear selector apparatus 1405 includes a ferromagnetic guide ring 1410 and a ferromagnetic housing 1420. The ferromagnetic housing 1420 contains an actuator coil 1415 (e.g., a solenoid). The ferromagnetic guide ring 1410 is connected to a spring 1425 configured to bias the ferromagnetic guide ring 1410. The ferromagnetic guide ring 1410 is connected to an engagement device 1430 that engages with one or more gears in the gearbox 285. In this way, movement of the ferromagnetic guide ring 1410 is engaged or disengaged with a particular gear in the gearbox 285, thereby setting the gear ratio.
The gear selector apparatus 1405 may be in an energized position (shown in fig. 14A) or a de-energized position (shown in fig. 14B). When in the energized position, the controller 200 provides current to the actuator coil 1415, thereby generating a high magnetic flux and creating detent force on the ferromagnetic guide ring 1410. The detent force overcomes the biasing force provided by the spring 1425 and provides a force opposite the spring 1425 such that the ferromagnetic guide ring 1410 contacts the ferromagnetic housing 1420 at the contact point 1500 (shown in fig. 15A).
When in the de-energized position, no current is provided to the actuator coil 1415 and no magnetic flux is generated. Thus, the biasing force of the spring 1425 pulls the ferromagnetic guide ring 1410 away from the ferromagnetic housing 1420 at the contact point 1500 (as shown in fig. 15B). In some cases, the power-off position is a default position of the gear selector apparatus 1405, thereby selecting a default gear ratio. By supplying current to or removing current from the gear selector device 1405, the controller 200 is able to switch gears in the gearbox 285.
In some embodiments, the controller 200 controls the gear ratio based on a set operating mode of the power tool 100. For example, using the input device 140, a user of the power tool 100 may set a torque mode (e.g., torque range, output torque, torque limit, etc.) of the power tool 100, and may set a rate mode (e.g., maximum rate, output rate, etc.) of the power tool 100. In some embodiments, the controller 200 calculates the torque limit and/or maximum rate based on input from the input device 140. The memory 225 may store a table indicating the amount of current to provide the actuator coil 1415 to achieve a particular gear ratio based on the operating mode of the power tool 100. Thus, although only two positions of the gear selector apparatus 1405 are described above with respect to fig. 14A and 14B, in some cases, more than two positions of the gear selector apparatus 1405 are implemented by changing the amount of current supplied to the actuator coil 1415. For example, to move the ferromagnetic guide ring 1410 to the energized position, the controller 200 provides a first current value to the actuator coil 1415. To move the ferromagnetic guide ring 1410 to a position between energized positions, the controller 200 provides a second current value to the actuator coil 1415 that is less than the first current value.
Fig. 16 illustrates a method 1600 for selecting a gear ratio of the power tool 100. Method 1600 may be performed by controller 200. At block 1605, the controller 200 receives an indication to drive the motor 280. For example, the controller 200 detects actuation of the trigger 125. At block 1610, the controller 200 determines whether the torque setting of the power tool 100 is within a low torque range (e.g., in a first mode of operation or a low torque mode of operation). For example, a user of the power tool 100 provides a torque setting to the controller 200 using the input device 140. In some cases, the torque setting is determined based on a maximum allowable current of the power tool 100. In some embodiments, the torque setting is determined based on a set gear ratio. For example, the high torque mode may have a gear ratio of 50:1, while the low torque mode may have a gear ratio of 15:1. When the torque setting of the power tool 100 is not within the low torque range (e.g., in the high torque mode), the method 1600 proceeds to block 1620 and the controller 200 drives the motor 280 according to the set operating mode. In some cases, to drive the motor 280 according to the set operation mode, the controller 200 controls the gear selector device 1405 to set the gear ratio according to the set operation mode.
When the torque of the power tool 100 is set in the low torque range, the method 1600 proceeds to block 1615. At block 1615, the controller 200 determines whether the power tool 100 is set to a low speed mode. For example, a user of the power tool 100 provides a rate setting to the controller 200 using the input device 140. In some embodiments, the rate mode is determined based on a set gear ratio. For example, the high speed mode may have a gear ratio of 50:1, while the low speed mode may have a gear ratio of 15:1. When the power tool 100 is not set to the low speed mode (e.g., the power tool 100 is set to the high speed mode), the method 1600 proceeds to block 1620 and the controller 200 drives the motor 280 according to the set operating mode. When the power tool 100 is in the low speed mode, the controller 200 proceeds to block 1625.
At block 1625, the controller 200 overrides the set operating mode of the power tool 100 and operates in a high speed mode. Accordingly, the controller 200 controls the gear selector apparatus 1405 to set the gear ratio according to the high speed mode regardless of the gear ratio selected by the user. In some embodiments, the controller 200 additionally limits the speed of the motor 280 to the speed limit of the low range chuck included in the gearbox 285. By overriding the set mode of operation while in the low torque setting and the low speed setting, the controller 200 avoids high torque overshoot and reduces flywheel energy while providing consistent torque output and maximizing speed.
Noise suppression
The audible noise range of humans typically falls between 20Hz and 20,000 Hz. The PWM frequency used to control the motor within the power tool typically falls between 6,000hz and 12,000 hz. In the embodiment described herein, the switches within the switching network 255 are controlled at a PWM frequency of approximately 8,000 hz. However, when the power tool 100 is used at low torque and low speed, the noise of the PWM frequency is more noticeable and may be annoying to the user of the power tool 100. In addition, the motor 280 generates noise during operation due to torque ripple, normal force ripple, or a combination thereof.
To counteract and otherwise reduce noise, the controller 200 may generate noise to cancel torque ripple,the PWM frequency of the switching network 255 may be adjusted, or a combination thereof may be performed. For example, in some embodiments, the controller 200 injects voltage frequencies in the audible range that cancel torque ripple noise by actively tracking the position of the motor 280 (e.g., using position signals from position sensors included in the auxiliary sensor 274). Fig. 17 provides an example block diagram 1700 for open loop control of injection voltage frequency based on the position of motor 280. At logic block 1705, the torque (T Motor ) And the angular velocity (ω) of the motor 280 Motor ) Provided to a look-up table 1702 (e.g., a ten second harmonic look-up table). The look-up table 1702 outputs a voltage magnitude and a phase offset based on the torque of the motor 280 and the angular velocity of the motor 280. The phase offset is summed with the electric rotor position (θ). The electric rotor position (θ) is multiplied by 12 to obtain the torque ripple associated with the twelve harmonics of the fundamental frequency of the motor 280. A sine function is applied to the result of the summation. The output of the sine function is then multiplied by the voltage magnitude from the look-up table 1702 to generate a harmonic output (e.g., a ten second harmonic output).
At block 1710, a similar operation is performed, for example, on the sixth harmonic. For example, the torque (T Motor ) And the angular velocity (ω) of the motor 280 Motor ) Provided to a lookup table 1708 (e.g., a sixth harmonic lookup table). The lookup table 1708 outputs a voltage magnitude and phase offset based on the torque of the motor 280 and the angular velocity of the motor 280. The phase offset is summed with the electric rotor position (θ) multiplied by 6 to obtain the torque ripple associated with the sixth harmonic of the fundamental frequency of motor 280. A sine function is applied to the result of the summation. The output of the sine function is then multiplied by the voltage magnitude from the look-up table 1708 to generate a harmonic output (e.g., a sixth harmonic output). While fig. 17 illustrates blocks 1705 and 1710 that generate a tenth harmonic output and a sixth harmonic output, respectively, additional logic blocks may be used to generate and sum additional harmonic outputs. In addition, other harmonic outputs may be generated in lieu of the tenth harmonic output and the sixth harmonic output based on the geometry of the motor 280 (e.g., based on the number of stator teeth, back emf type, pole pair number, etc.).
In some implementationsIn an embodiment, the field oriented control module 1715 receives a current command (i q, command ) Current (i) of each phase of motor abc ) And the angle or position (θ) of the motor. The field oriented control module 1715 outputs a voltage command (e.g., a voltage command signal) V q, command And V d, order Or a command indicating the voltage requested by the regulator of the field oriented control module 1715. For V q, command Summed with the sum of the harmonic outputs of logic blocks 1705 and 1710 to generate a total harmonic output. Sum total harmonic output V d, order Is provided to a PWM conversion module 1720 that outputs PWM commands PWM for driving the switching network 255 abc, command . The field orientation control module 1715 controls V by manipulating q, command And V d, order Commands to maintain current control for d-current and q-current. In some cases, by combining V q, command And V d, order The magnitude of the command is compared with the voltage of the battery pack 150 to compare V q, command And V d, order Converted to PWM commands.
The noise injection provided by logic blocks 1705 and 1710 is a high frequency electromagnetic field that introduces torque pulses equal and opposite in magnitude to the naturally occurring torque pulses of motor 280 (or the natural noise of motor 280), thereby producing a substantially net zero amount of torque pulses and reducing torque pulses that are acoustic noise sources. The injected frequency is synchronized with the actual torque ripple of the motor 280 by using the position of the motor 280 at the time of noise generation.
Fig. 17 provides a specific example of noise injection to reduce torque ripple using, for example, the sixth and tenth harmonics of the torque ripple. Other embodiments may use different harmonics than the sixth and tenth harmonics or frequencies in the audible range to reduce acoustic noise from the motor 280.
In some embodiments, to address noise used to control the PWM frequency of the switching network 255, the controller 200 may dynamically adjust the PWM frequency (e.g., PWM commands provided by the bus current controller 320) based on feedback data associated with the operation of the power tool 100. In this way, the controller 200 shifts the PWM frequency out of the audible range when the switching loss is low. For example, fig. 18 provides an example average power loss per FET compared to the bus current of motor 280 and the switching frequency of switching network 255. Similarly, fig. 19 provides the switching frequency of the switching network 255 compared to the bus current and power loss per FET of the motor 280. As shown in fig. 18 and 19, for a given PWM frequency, a greater bus current correlates to a greater average power loss per FET. Thus, in some cases, the controller 200 uses the bus current of the motor 280 (e.g., provided by the current sensor 270) to adjust the PWM frequency.
Referring primarily to fig. 18, a plurality of functions 1800 provide average power loss per FET for a given PWM frequency and bus current value. The plurality of functions 1800 includes a control function 1810, which in some cases is a function implemented by the controller 200 to reduce noise. For example, under low power operation (such as operation with a bus current value less than approximately 48A), the controller 200 increases the PWM frequency according to the bus current value. When the bus current value is approximately 40A, the controller 200 sets the PWM frequency to approximately 9.2kHz. At approximately 30A, the controller 200 sets the PWM frequency to approximately 11kHz. At approximately 20A, the controller 200 sets the PWM frequency to approximately 14.5kHz. At approximately 10A, the controller 200 sets the PWM frequency to approximately 20kHz. Accordingly, the controller 200 increases the PWM frequency when the power tool 100 is operating in a low power condition.
During high power operation (such as operation with bus current values greater than approximately 48A), the controller 200 maintains the PWM frequency at approximately 8kHz. If the operation of the power tool 100 transitions from low power operation to high power operation, the control function 1810 provides a smooth transition from an inaudible PWM frequency to an audible PWM frequency, thereby providing a perception of increased load of the power tool 100. The feedback data used to control the PWM frequency is naturally noisy and provides natural dithering to the PWM frequency, which can scatter the noise to reduce its harshness.
Fig. 20 illustrates a method 2000 for adjusting PWM frequency. The method 2000 may be performed by the controller 200. At block 2005, the controller 200 drives the motor 280 by controlling the switching network 255 at the first PWM frequency. For example, in performing low power operations, the controller 200 controls the switching network 255 at 16 kHz. At block 2010, the controller 200 receives a current signal indicative of a bus current of the motor 280. For example, the current sensor 270 provides a current signal to the controller 200.
At block 2015, the controller 200 selects a second PWM frequency based on the current signal. For example, in some embodiments, memory 225 stores control function 1810 as a table mapping bus current values to PWM frequency values. The controller 200 compares the bus current value to the table to determine a second PWM frequency value. At block 2020, controller 200 drives motor 280 by controlling switching network 255 at the second PWM frequency. In some embodiments, the controller 200 continues to receive the current signal and continuously adjust the PWM frequency during operation of the motor 280. In some embodiments, the PWM frequency is increased to achieve low torque and/or low speed operation. In other embodiments, the PWM frequency is high by default and decreases as the output power increases.
In some cases, the controller 200 dynamically adjusts the PWM frequency based on the temperature of the switching network 255 (e.g., as indicated by the temperature sensor 272). For example, as the measured temperature of the switching network 255 increases, the controller 200 decreases the PWM frequency, thereby avoiding an overheating event of the switching network 255. In some embodiments, controller 200 adjusts the PWM frequency based on both the bus current and the temperature of switching network 255. For example, when the temperature of the switching network 255 rises above the temperature threshold, the controller 200 may decrease the PWM frequency determined based on the bus current (at block 2015). In some embodiments, the motor rate is additionally or alternatively used to control the PWM frequency.
Representative features
Representative features are set forth in the following clauses which are independent or can be combined in any combination with one or more features disclosed in the text and/or drawings of the specification.
1. A power tool including an electronic clutch, the power tool comprising:
a motor;
a trigger; and
a controller connected to the trigger and the motor, the controller configured to:
power is provided to the motor in response to actuation of the trigger,
The rate of the motor is determined and,
activating the electronic clutch to electronically brake the motor for a second period of time in response to determining that the rate of the motor has fallen by a rate-falling threshold within the first period of time, an
Power is provided to the motor in response to the second period of time having elapsed.
2. The power tool of clause 1, wherein the controller is further configured to:
determining a torque value to drive the motor based on the rate of the motor and the rate command signal;
comparing the torque value to a torque-to-current look-up table;
determining a current value provided to the motor based on the comparison; and
the current value is provided to the motor to drive the motor.
3. The power tool of clause 2, further comprising:
a current sensor configured to provide a current signal indicative of a current of the motor,
wherein the controller is further configured to:
receiving from the current sensor the current signals indicative of the current of the motor,
determining a Pulse Width Modulation (PWM) duty cycle based on the current of the motor and the current value, an
The motor is driven according to the PWM duty cycle.
4. The power tool of any preceding clause, further comprising:
A torque sensor configured to provide a torque signal indicative of a torque of the motor,
wherein the controller is further configured to:
the torque signals indicative of the torque of the motor are received from the torque sensor,
determining a Pulse Width Modulation (PWM) duty cycle based on the torque of the motor and the desired torque, and
the motor is driven according to the PWM duty cycle.
5. The power tool of any preceding clause, wherein the controller is further configured to:
the motor is controlled according to a first mode of operation for a third period of time in response to actuation of the trigger.
6. The power tool of clause 5, wherein the controller is further configured to:
limiting motor current provided to the motor for a fourth period of time in response to the third period of time having elapsed.
7. The power tool of clause 6, wherein the controller is further configured to:
the motor is controlled according to the first operating mode in response to the fourth period of time having elapsed.
8. The power tool of any preceding clause, further comprising:
an input device configured to set a desired torque value, and wherein the controller is further configured to:
Determining a torque limit based on the desired torque value, an
The motor is controlled based in part on the torque limit.
9. The power tool of clause 8, wherein the input device is a torque ring.
10. The power tool of any preceding clause, wherein the controller is configured to:
detecting a high load condition of the motor based on a rate of the motor; and
the torque value driving the motor is limited in response to a high load condition of the motor.
11. A method for operating a power tool including an electronic clutch, the method comprising:
providing power to the motor in response to actuation of the trigger;
determining a rate of the motor;
determining whether the rate of the motor has fallen by a rate-falling threshold within a first time period;
activating the electronic clutch to electronically brake the motor for a second period of time in response to determining that the rate of the motor has decreased by the rate-decrease threshold within the first period of time; and
power is provided to the motor in response to the second period of time having elapsed.
12. The method of clause 11, further comprising:
determining a torque value to drive the motor based on the rate of the motor and the rate command;
Comparing the torque value to a torque-to-current look-up table;
determining a current value provided to the motor based on the comparison; and
the current value is provided to the motor to drive the motor.
13. The method of clause 12, further comprising:
receiving a current signal from a current sensor indicative of a current of the motor;
determining a Pulse Width Modulation (PWM) duty cycle based on the current of the motor and the current value; and
the motor is driven according to the PWM duty cycle.
14. The method of any one of clauses 11 to 12, further comprising:
a torque signal indicative of the torque of the motor is received from a torque sensor,
determining a Pulse Width Modulation (PWM) duty cycle based on the torque of the motor and the desired torque, and
the motor is driven according to the PWM duty cycle.
15. The method of any one of clauses 11 to 14, further comprising:
controlling the motor for a third period of time according to a first mode of operation in response to actuation of the trigger; and
limiting motor current provided to the motor for a fourth period of time in response to the third period of time having elapsed.
16. The method of any one of clauses 11 to 15, further comprising:
determining a torque limit based on the desired torque value; and
The motor is controlled based in part on the torque limit.
17. The method of any one of clauses 11 to 16, further comprising:
detecting a high load condition of the motor based on a rate of the motor; and
the torque value driving the motor is limited in response to a high load condition of the motor.
18. The method of any one of clauses 11 to 17, further comprising:
receiving a temperature signal from a temperature sensor indicative of a temperature of a mechanism driven by the motor;
determining a torque value to drive the motor based on the temperature signals; and
the motor is driven according to the torque value.
19. A power tool including an electronic clutch, the power tool comprising:
a motor; and
a controller connected to the motor, the controller configured to:
the motor is driven according to a first rate setting,
the rate of the motor is determined and,
determining whether the speed of the motor is greater than or equal to a first speed threshold when at the first speed setting,
driving the motor according to a second rate setting in response to the rate of the motor being greater than or equal to the first rate threshold,
determining if the speed of the motor is less than a second speed threshold when at the second speed setting, and
The motor current is limited for a clutch timeout period in response to determining that the rate of the motor is below the second rate threshold.
20. The power tool of clause 19, wherein the controller is further configured to:
the motor is driven according to the first rate setting in response to the clutch timeout period having elapsed.
21. The power tool of clause 19 or clause 20, wherein the first rate threshold is equal to the second rate threshold.
22. The power tool of any one of clauses 19-21, further comprising an input device configured to set a desired torque value, and wherein the controller is further configured to:
calculating a torque limit based on the desired torque value, and
the motor is controlled based in part on the torque limit.
23. A power tool, comprising:
a motor;
a gear train coupled to the motor;
a gear selector device configured to set a gear ratio of the gear train;
a trigger; and
a controller connected to the motor, the trigger and the gear selector device, the controller configured to:
an indication to drive the motor is received from the trigger,
A torque setting of the power tool is determined,
determining a rate setting for the power tool, and
the gear selector means is controlled to set a gear ratio of the gear train based on the torque setting and the speed setting.
24. The power tool of clause 23, wherein the gear selector device comprises:
a solenoid;
a ferromagnetic guide ring; and
a spring coupled to the ferromagnetic guide ring.
25. The power tool of clause 24, wherein the controller is further configured to control the gear selector device by providing current to the solenoid to generate a magnetic flux, and wherein the magnetic flux provides a force on the ferromagnetic guide ring that is greater than and opposite to the force provided on the ferromagnetic guide ring by the spring.
26. The power tool of any one of clauses 23-25, wherein the controller is further configured to:
determining whether the torque setting of the power tool is within a low torque range; and
the gear selector means is controlled to set the gear ratio to a default gear ratio in response to the torque setting being out of the low torque range.
27. The power tool of clause 26, wherein the controller is further configured to:
Determining whether the rate setting of the power tool is in a low speed mode; and
the gear selector means is controlled to set the gear ratio to the default gear ratio in response to the rate setting of the power tool not being in the low speed mode.
28. The power tool of clause 27, wherein the controller is further configured to:
in response to the torque setting of the power tool being within the low torque range and in response to the rate of the power tool being set to the low speed mode, the gear selector means is controlled to set the gear ratio to a second gear ratio different from the default gear ratio.
29. A method for operating a power tool, the method comprising:
receiving an indication of a drive motor from a trigger;
determining a torque setting for the power tool;
determining a rate setting for the power tool; and
based on the torque setting and the speed setting, a gear selector device is controlled to set a gear ratio of a gear train coupled to the motor.
30. The method of clause 29, further comprising:
the gear selector apparatus is controlled by supplying current to the solenoid to generate magnetic flux.
31. The method of any one of clauses 29 to 30, further comprising:
Determining whether the torque setting of the power tool is within a low torque range; and
the gear selector means is controlled to set the gear ratio to a default gear ratio in response to the torque setting being out of the low torque range.
32. The method of clause 31, further comprising:
determining whether the rate setting of the power tool is in a low speed mode; and
the gear selector means is controlled to set the gear ratio to the default gear ratio in response to the rate setting of the power tool not being in the low speed mode.
33. The method of clause 32, further comprising:
in response to the torque setting of the power tool being within the low torque range and in response to the rate of the power tool being set to the low speed mode, the gear selector means is controlled to set the gear ratio to a second gear ratio different from the default gear ratio.
34. A power tool, comprising:
a motor;
a battery pack;
a switching network connected between the motor and the battery pack and configured to provide power to the motor, wherein the switching network comprises a plurality of switches;
a current sensor configured to sense a current of the motor;
A trigger; and
a controller connected to the switching network, the trigger, and the current sensor, the controller configured to:
in response to actuation of the trigger, driving the motor by controlling the plurality of switches at a first Pulse Width Modulation (PWM) frequency,
a current signal indicative of the current of the motor is received from the current sensor,
selecting a second PWM frequency based on the current signal, and
the motor is driven by controlling the plurality of switches at the second PWM frequency.
35. The power tool of clause 34, further comprising:
a position sensor configured to sense a position of the motor;
wherein the controller is further configured to:
a position signal indicative of the position of the motor is received from the position sensor,
generating a noise signal based on the position of the motor, and
the noise signal is injected into the voltage command signal, which is opposite in magnitude to the natural noise generated by the motor.
36. The power tool of clause 35, wherein to generate the noise signal, the controller is further configured to:
comparing the torque of the motor and the angular velocity of the motor with a first lookup table to generate a first voltage magnitude and a first phase offset;
Summing the first phase offset with a first harmonic of a frequency of the motor-generated torque ripple to generate a first harmonic sum; and
the first voltage magnitude is summed with the first harmonic sum.
37. The power tool of clause 36, wherein to generate the noise signal, the controller is further configured to:
comparing the torque of the motor and the angular velocity of the motor with a second lookup table to generate a second voltage magnitude and a second phase offset;
summing the second phase offset with a second harmonic of the frequency of the torque ripple generated by the motor to generate a second harmonic sum; and
the second voltage magnitude is summed with the second harmonic sum.
38. The power tool of any one of clauses 34 to 37, wherein the controller is further configured to select the second PWM signal by:
the current signal is compared to a table stored in memory.
39. The power tool of any one of clauses 34-38, further comprising:
a temperature sensor configured to sense temperatures of the plurality of switches,
wherein the controller is further configured to:
a temperature signal indicative of the temperature of the plurality of switches is received from the temperature sensor,
Adjusting the second PWM frequency based on the temperature signal to generate a third PWM frequency, and
the motor is driven by controlling the plurality of switches at the third PWM frequency.
40. A method for operating a power tool, the method comprising:
driving a motor by controlling a plurality of switches at a first Pulse Width Modulation (PWM) frequency in response to actuation of a trigger, wherein the plurality of switches are connected between the motor and a battery pack and configured to provide power to the motor;
receiving a current signal from a current sensor indicative of a current of the motor;
selecting a second PWM frequency based on the current signal; and
the motor is driven by controlling the plurality of switches at the second PWM frequency.
41. The method of clause 40, further comprising:
receiving a position signal from a position sensor indicating a position of the motor;
generating a noise signal based on the position of the motor; and
the noise signal is injected into the voltage command signal, which is opposite in magnitude to the natural noise generated by the motor.
42. The method of clause 41, wherein generating the noise signal further comprises:
comparing the torque of the motor and the angular velocity of the motor with a first lookup table to generate a first voltage magnitude and a first phase offset;
Summing the first phase offset with a first harmonic of a frequency of the motor-generated torque ripple to generate a first harmonic sum; and
the first voltage magnitude is summed with the first harmonic sum.
43. The method of clause 42, wherein generating the noise signal further comprises:
comparing the torque of the motor and the angular velocity of the motor with a second lookup table to generate a second voltage magnitude and a second phase offset;
summing the second phase offset with a second harmonic of the frequency of the torque ripple generated by the motor to generate a second harmonic sum; and
the second voltage magnitude is summed with the second harmonic sum.
44. The method of any of clauses 40 to 43, wherein selecting the second PWM frequency comprises comparing the current signal to a table.
45. The method of any one of clauses 40 to 44, further comprising:
receiving temperature signals from a temperature sensor indicative of the temperatures of the plurality of switches;
adjusting the second PWM frequency based on the temperature signal to generate a third PWM frequency; and
the motor is driven by controlling the plurality of switches at the third PWM frequency.
Accordingly, the embodiments provided herein describe, among other things, systems and methods for electronically limiting torque of a power tool. Various features and advantages are set forth in the following claims.

Claims (20)

1. A power tool including an electronic clutch, the power tool comprising:
a motor;
a trigger; and
a controller connected to the trigger and the motor, the controller configured to:
power is provided to the motor in response to actuation of the trigger,
the rate of the motor is determined and,
activating the electronic clutch to electronically brake the motor for a second period of time in response to determining that the rate of the motor has fallen by a rate-falling threshold within the first period of time, an
Power is provided to the motor in response to the second period of time having elapsed.
2. The power tool of claim 1, wherein the controller is further configured to:
determining a torque value to drive the motor based on the rate of the motor and the rate command signal;
comparing the torque value to a torque-to-current look-up table;
determining a current value provided to the motor based on the comparison; and
the current value is provided to the motor to drive the motor.
3. The power tool of claim 2, further comprising:
a current sensor configured to provide a current signal indicative of a current of the motor,
Wherein the controller is further configured to:
receiving from the current sensor the current signals indicative of the current of the motor,
determining a Pulse Width Modulation (PWM) duty cycle based on the current of the motor and the current value, an
The motor is driven according to the PWM duty cycle.
4. The power tool of claim 1, further comprising:
a torque sensor configured to provide a torque signal indicative of a torque of the motor,
wherein the controller is further configured to:
the torque signals indicative of the torque of the motor are received from the torque sensor,
determining a Pulse Width Modulation (PWM) duty cycle based on the torque of the motor and the desired torque, and
the motor is driven according to the PWM duty cycle.
5. The power tool of claim 1, wherein the controller is further configured to:
the motor is controlled according to a first mode of operation for a third period of time in response to actuation of the trigger.
6. The power tool of claim 5, wherein the controller is further configured to:
limiting motor current provided to the motor for a fourth period of time in response to the third period of time having elapsed.
7. The power tool of claim 6, wherein the controller is further configured to:
The motor is controlled according to the first operating mode in response to the fourth period of time having elapsed.
8. The power tool of claim 1, further comprising:
an input device configured to set a desired torque value, and wherein the controller is further configured to:
determining a torque limit based on the desired torque value, an
The motor is controlled based in part on the torque limit.
9. The power tool of claim 1, wherein the controller is configured to:
detecting a high load condition of the motor based on a rate of the motor; and
the torque value driving the motor is limited in response to a high load condition of the motor.
10. A method for operating a power tool including an electronic clutch, the method comprising:
providing power to the motor in response to actuation of the trigger;
determining a rate of the motor;
determining whether the rate of the motor has fallen by a rate-falling threshold within a first time period;
activating the electronic clutch to electronically brake the motor for a second period of time in response to determining that the rate of the motor has decreased by the rate-decrease threshold within the first period of time; and
Power is provided to the motor in response to the second period of time having elapsed.
11. The method of claim 10, further comprising:
determining a torque value to drive the motor based on the rate of the motor and the rate command;
comparing the torque value to a torque-to-current look-up table;
determining a current value provided to the motor based on the comparison; and
the current value is provided to the motor to drive the motor.
12. The method of claim 11, further comprising:
receiving a current signal from a current sensor indicative of a current of the motor;
determining a Pulse Width Modulation (PWM) duty cycle based on the current of the motor and the current value; and
the motor is driven according to the PWM duty cycle.
13. The method of claim 10, further comprising:
a torque signal indicative of the torque of the motor is received from a torque sensor,
determining a Pulse Width Modulation (PWM) duty cycle based on the torque of the motor and the desired torque, and
the motor is driven according to the PWM duty cycle.
14. The method of claim 10, further comprising:
determining a torque limit based on the desired torque value; and
the motor is controlled based in part on the torque limit.
15. The method of claim 10, further comprising:
Detecting a high load condition of the motor based on a rate of the motor; and
the torque value driving the motor is limited in response to a high load condition of the motor.
16. The method of claim 10, further comprising:
receiving a temperature signal from a temperature sensor indicative of a temperature of a mechanism driven by the motor;
determining a torque value to drive the motor based on the temperature signals; and
the motor is driven according to the torque value.
17. A power tool including an electronic clutch, the power tool comprising:
a motor; and
a controller connected to the motor, the controller configured to:
the motor is driven according to a first rate setting,
the rate of the motor is determined and,
determining whether the speed of the motor is greater than or equal to a first speed threshold when at the first speed setting,
driving the motor according to a second rate setting in response to the rate of the motor being greater than or equal to the first rate threshold,
determining if the speed of the motor is less than a second speed threshold when at the second speed setting, and
the motor current is limited for a clutch timeout period in response to determining that the rate of the motor is below the second rate threshold.
18. The power tool of claim 17, wherein the controller is further configured to:
the motor is driven according to the first rate setting in response to the clutch timeout period having elapsed.
19. The power tool of claim 17, wherein the first rate threshold is equal to the second rate threshold.
20. The power tool of claim 17, further comprising an input device configured to set a desired torque value, and wherein the controller is further configured to:
calculating a torque limit based on the desired torque value, and
the motor is controlled based in part on the torque limit.
CN202310302829.6A 2022-03-23 2023-03-23 Electronic clutch for power tool Pending CN116803620A (en)

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
US63/322,949 2022-03-23
US202263384891P 2022-11-23 2022-11-23
US63/384,891 2022-11-23

Publications (1)

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CN116803620A true CN116803620A (en) 2023-09-26

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Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
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