Electric tool

Abstract

The electric tool comprises a shell, a battery pack socket, a brushless motor, one or more Hall effect sensors, a power switch circuit, a single current sensor and an electronic controller. The battery pack receptacle is configured to receive a battery pack. The motor shaft is arranged to generate a rotational output to the drive mechanism. The one or more Hall effect sensors are configured to generate an output signal corresponding to a rotational position of the brushless motor. The power switching circuit is configured to provide a supply of power from the battery pack to the brushless motor. A single current sensor is disposed between the battery pack and the brushless motor. A single current sensor is configured to determine a supply of power from the battery pack to the brushless motor. The electronic controller is configured to implement field oriented control ("FOC") of the brushless motor.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 617,819, filed January 5, 2024, and U.S. Provisional Patent Application No. 63 / 555,185, filed February 19, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments described in this utility model relate to power tools including a brushless DC motor. Background Technology

[0004] A conventional brushless direct current (“DC”) motor comprises a stator and a rotor, the rotor being configured to rotate relative to the stator by a magnetic field generated in one or more phases of the stator. Typically, the stator and rotor are separated by an air gap. To properly generate the magnetic field in the correct phase, a conventional brushless DC motor further includes multiple sensors, such as Hall effect sensors, configured to sense the angular position of the rotor relative to the stator. To properly generate the magnetic field in the correct phase, one or more control algorithms are used to control the energization of the stator phase. Utility Model Content

[0005] The embodiments described in this utility model relate to power tools configured to achieve sensed field oriented control (“sFOC”). In sFOC, both the stator and rotor generate magnetic flux. Specifically, the stator magnetic flux current i d and stator torque current i q It constitutes the stator current vector I s The stator flux has two components. Therefore, the stator flux can be determined as a function of the stator current. The goal of sFOC is to align the stator flux orthogonally to the rotor flux. Once the rotor position is known, the power tool controls the phase of the stator to generate the appropriate magnetic field, which keeps the stator flux orthogonal to the rotor flux. Controlling the motor via sFOC offers various benefits, such as independent control of motor speed and motor torque.

[0006] Unlike conventional motor control topologies (e.g., trapezoidal motor control, three-phase FOC, etc.), sFOC eliminates the need for shunts on the low-side branches or phases of the voltage source inverter (“VSI”). Instead, sFOC places a shunt on the VSI bus and samples the inverter bus current when it equals the phase current. The three-phase current information can then be reconstructed based on the measurements, completing the FOC current loop.

[0007] Furthermore, unlike FOC which implements shunt resistors on the VSI phase or branch, sFOC does not require additional current sensing components on the bus for overcurrent protection (“OCP”).

[0008] Furthermore, unlike the classic block commutation control topology commonly used in power tools and outdoor electric equipment, sFOC exhibits better dynamic and steady-state performance as well as controllability.

[0009] The power tool of this invention includes a housing, a battery socket, a brushless motor, one or more Hall effect sensors, a power switching circuit, a single current sensor, and an electronic controller. The battery socket is disposed on the housing and configured to receive a battery pack. The brushless motor is disposed within the housing. The brushless motor includes a rotor and a stator. The rotor is coupled to a motor shaft arranged to rotate about a longitudinal axis. The longitudinal axis extends through the motor shaft. The motor shaft is arranged to produce a rotational output to a drive mechanism. One or more Hall effect sensors are disposed adjacent to the brushless motor. The one or more Hall effect sensors are configured to generate an output signal corresponding to the rotational position of the brushless motor. The power switching circuit is configured to supply power from the battery pack to the brushless motor. The single current sensor is disposed between the battery pack and the brushless motor. The single current sensor is configured to determine the power supply from the battery pack to the brushless motor. The electronic controller is connected to one or more Hall effect sensors and the power switching circuit. The electronic controller is configured to implement field-oriented control (“FOC”) of the brushless motor.

[0010] In some aspects, the power tool further includes a mixed-signal programmable logic device electrically connected to a single current sensor, the mixed-signal programmable logic device being configured to detect fault conditions.

[0011] In some respects, the fault condition is a short circuit.

[0012] In some respects, the electronic controller is further configured to generate current commands using the output signals from the speed regulator and one or more position sensors.

[0013] In some respects, the electronic controller is further configured to determine the rotor speed based on output signals from one or more position sensors, and to use a speed regulator to generate a current command based on the rotor speed and the target speed.

[0014] In some respects, the electronic controller is further configured to operate in torque mode based on user selection, receive torque input commands based on user input, and generate current commands based on torque input commands.

[0015] In some respects, the electronic controller is further configured to determine a first feedforward term and a second feedforward term based on a signal from a single current sensor and an output signal from one or more position sensors, wherein the first feedforward term corresponds to the motor speed and the second feedforward term corresponds to the motor torque.

[0016] In some aspects, the controller is further configured to receive output signals from one or more position sensors during the position control section, determine the parameters of the brushless motor based on the output signals from one or more position sensors, and use FOC to determine the drive parameters of the motor based on the parameters of the brushless motor during the multisampling section, generate drive commands based on the drive parameters, and drive the brushless motor based on the drive commands.

[0017] In some respects, the position control section operates at a first frequency, while the multisampling section operates at a second frequency greater than the first frequency.

[0018] In some respects, the first frequency is the PWM frequency corresponding to the frequency used to control the rotation of the motor, while the second frequency is a multiple of the first frequency.

[0019] In some aspects, the electronic controller is further configured to determine the rotor speed based on output signals from one or more position sensors during the position control section, and to generate a current command using a speed regulator during the external input section, the current command being based on the rotor speed and the target speed.

[0020] In some respects, the position control section operates at a first frequency, while the external input section operates at a second frequency, which is lower than the first frequency.

[0021] The method for controlling a brushless motor of a handheld power tool described in this utility model includes: during an external input section, generating a current command using a speed regulator and output signals received from one or more position sensors; during a position control section, determining a first feedforward term and a second feedforward term based on signals from the current command and output signals from one or more position sensors, and determining parameters of the brushless motor based on the first feedforward term and the second feedforward term; and during a multisampling section, determining drive parameters of the motor based on the parameters of the brushless motor using a FOC, generating a drive command based on the drive parameters, and driving the brushless motor based on the drive command.

[0022] In some respects, the first feedforward term corresponds to the motor speed, while the second feedforward term corresponds to the motor torque.

[0023] In some respects, the parameters of a brushless motor include at least one of the brushless motor's rotational position, speed, or acceleration.

[0024] In some respects, the parameters of a brushless motor are the multiple duty cycles of each phase of the motor.

[0025] The power tool of this invention includes a housing, a battery socket, a brushless motor, one or more position sensors, a single current sensor, and an electronic controller. The battery socket is disposed on the housing and configured to receive a battery pack. The brushless motor is disposed within the housing and includes a rotor and a stator. The rotor is coupled to a motor shaft arranged to rotate about a longitudinal axis extending through the motor shaft, and the motor shaft is arranged to generate a rotational output to a drive mechanism. One or more position sensors are disposed adjacent to the brushless motor and configured to generate an output signal corresponding to the rotational position of the brushless motor. A power switching circuit is configured to supply power from the battery pack to the brushless motor. The single current sensor is disposed between the battery pack and the brushless motor and configured to determine the power supply from the battery pack to the brushless motor. The electronic controller is configured to implement field-oriented control (“FOC”) of the brushless motor. The electronic controller is configured to generate a current command using a speed regulator and output signals received from one or more position sensors during the external input section; during the position control section, a first feedforward term and a second feedforward term are determined based on the signal from the current command and the output signals from one or more position sensors, and parameters of the brushless motor are determined based on the first feedforward term and the second feedforward term; and during the multisampling section, the drive parameters of the motor are determined using FOC based on the parameters of the brushless motor, a drive command is generated based on the drive parameters, and the brushless motor is driven based on the drive command.

[0026] In some respects, the position control section operates at a first frequency, and the multisampling section operates at a second frequency greater than the first frequency.

[0027] In some respects, the first frequency is a PWM frequency corresponding to the frequency used to control the rotation of the motor, and the second frequency is a multiple of the first frequency.

[0028] In some respects, the external input section operates at a third frequency, which is lower than the first frequency.

[0029] Unless the context clearly indicates otherwise, the articles “a,” “an,” and “the” should not be interpreted as meaning “one” or “only one.” Instead, these articles should be interpreted as meaning “at least one” or “one or more.” Similarly, when the terms “the” or “said” are used to refer to a noun previously introduced by the indefinite articles “a” or “an,” “the” and “said” mean “at least one” or “one or more,” unless the usage clearly indicates otherwise.

[0030] Furthermore, it should be understood that implementations may include hardware, software, and electronic components or modules, which, for the purposes of discussion, may be illustrated and described as if most components were implemented solely in hardware. However, those skilled in the art will recognize from this detailed description that, in at least one implementation, the electronic aspects may be implemented in software (e.g., stored on a non-transitory computer-readable medium) executable by one or more processing units (such as microprocessors and / or application-specific integrated circuits (“ASICs”)). Therefore, it should be noted that implementations may be implemented using a plurality of hardware and software-based devices and a plurality of different structural components. For example, “server,” “computing device,” “controller,” “processor,” etc., as described in the specification may include one or more processing units, one or more computer-readable medium modules, one or more input / output interfaces, and various connectors (e.g., system buses) for connection components.

[0031] Related terms used in conjunction with quantities or conditions, such as, for example, “about,” “approximately,” “generally,” etc., will be understood by one of ordinary skill in the art to include the stated value and have a meaning defined by the context (e.g., the term includes at least the degree of error associated with measurement accuracy, the tolerance associated with a particular value [e.g., manufacturing, assembly, use, etc.]). Such terms should also be considered to disclose a range defined by the absolute values ​​of two endpoints. For example, the expression “about 2 to about 4” also discloses a range of “2 to 4.” Related terms may refer to a percentage added to or subtracted from the indicated value (e.g., 1%, 5%, 10%).

[0032] It should be understood that although some figures illustrate hardware and software located within a particular device, these descriptions are for illustrative purposes only. Functions described in this invention as being performed by a single component can be performed by multiple components in a distributed manner. Similarly, functions performed by multiple components can be combined and performed by a single component. In some embodiments, the illustrated components can be combined or divided into separate software, firmware, and / or hardware. For example, logic and processing can be distributed among multiple electronic processors, rather than residing within and being performed by a single electronic processor. Regardless of how the hardware and software components are combined or divided, the hardware and software components can reside on the same computing device or can be distributed among different computing devices connected via one or more networks or other suitable communication links. Similarly, components described as performing specific functions can also perform additional functions not described in this invention. For example, a device or structure "configured" in a certain way is at least configured in that way, but can also be configured in a way not explicitly listed.

[0033] Therefore, in the claims, if the device, method, or system is claimed to include, for example, a controller, control unit, electronic processor, computing device, logic element, module, memory module, communication channel or network, or other elements configured in a certain way to perform, for example, multiple functions, then the claim or claim element should be interpreted as meaning one or more such elements, any one of which is configured as claimed to perform, for example, any one or more of the multiple functions, such that the one or more elements together perform multiple functions.

[0034] Other aspects of the implementation will become apparent upon careful reading of the detailed description and accompanying drawings. Attached Figure Description

[0035] Figure 1 A power tool implementing sensed field orientation control according to some embodiments is shown.

[0036] Figure 2 A cross-sectional view of a power tool implementing sensed field orientation control according to some embodiments is shown.

[0037] Figure 3 A control system for implementing sensed field orientation control for a power tool, according to some embodiments, is shown.

[0038] Figure 4 This is a block diagram of a control system for implementing sensor-oriented field control for power tools, according to some implementation methods.

[0039] Figure 5 This is a block diagram of the control topology for implementing field-oriented control of power tools according to some implementation methods.

[0040] Figure 6 A motor timing diagram for a power tool used to implement sensed field orientation control is shown according to some embodiments. Detailed Implementation

[0041] The embodiments described in this utility model relate to power tools, such as handheld power tools, which actually have a sensed brushless DC motor (“sensored motor”) and sensed field orientation control (“sFOC”).

[0042] Figure 1 A power tool 100 implementing sFOC is shown. Figure 1In the illustrated embodiment, power tool 100 is a drill bit / driver. In other embodiments, power tool 100 is a different type of power tool (e.g., impact wrench, ratchet, saw, hammer drill, impact driver, rotary hammer, grinder, blower, trimmer, chainsaw, etc.). Power tool 100 includes a housing 105 and a battery pack interface 110 or socket for connecting power tool 100 to, for example, a battery pack. In some embodiments, battery pack interface 110 may be configured to connect power tool 100 to another device.

[0043] Figure 2 It shows Figure 1 The image shows a cross-section of a power tool 100. The power tool 100 includes at least one printed circuit board (“PCB”) 205 for various components of the power tool 100. In some embodiments, PCB 205 is a control PCB. In addition to or as an alternative to a control PCB, the power tool 100 may include a power PCB, a forward / reverse PCB, and / or a light-emitting diode (“LED”) PCB. The power tool 100 may further include a motor 210. In some embodiments, the motor 210 may be a sensor motor. Figure 2 The diagram also shows a drive mechanism 215 for transmitting the rotary output of motor 210 to output unit 220, and a cooling fan 225 rotated by motor 210 for providing cooling airflow over components of power tool 100. Power tool 100 may further include a trigger 230 configured to be actuated by a user. In some embodiments, the actuation amount of trigger 230 can be used to determine the amount of power supplied to motor 210. Power tool 100 may further include a work light 235 configured to illuminate the working area of ​​power tool 100. In some embodiments, work light 235 may be mounted below drive mechanism 215. In some embodiments, work light 235 may be configured to be activated in response to actuation of trigger 230.

[0044] Figure 3 A power tool for achieving sensed field orientation control is shown (e.g., Figure 1 The power tool 100 has a control system 300. The control system 300 includes a controller 304. The controller 304 is electrically connected and / or communicatively connected to various modules or components of the power tool. For example, the illustrated controller 304 is electrically connected to a motor 308 (e.g., Figure 2 Motor 210), battery pack interface 312 (e.g., Figure 1 Battery pack interface 110), (connected to trigger 320, for example, Figure 2The motor 308 includes a trigger switch 316 (trigger 230), one or more sensors (including at least a current sensor 324, a Hall effect sensor 328, and a temperature sensor), one or more indicators 332, one or more user input modules 336, a power input module 340, a gate controller 344 (connected to the inverter 348), and a mixed-signal programmable logic device (“MS-PLD”) 350. The motor 308 includes a rotor, a stator, and a shaft that rotates about a longitudinal axis. In some embodiments, the motor 308 is a three-phase permanent magnet synchronous motor (“PMSM”) or a brushless DC (“BLDC”) motor employing a Hall effect position sensor (“HPS”). In other embodiments, the motor 308 may implement other position sensors, including magnetic sensors, inductive sensors, magnetic or inductive sine / cosine encoders, etc.

[0045] The controller 304 includes a combination of hardware and software, which can be used in particular to control the operation of power tools, monitor the operation of power tools, activate one or more indicators 332 (e.g., LEDs), etc. The gate controller 344 is configured to control the inverter 348 to convert DC power supply into a three-phase signal for supplying power to the phases of the motor 308. The current sensor 324 is configured to, for example, sense the current drawn from the battery pack interface 312. The temperature sensor is configured to, for example, sense the temperature of the inverter 348. The MS-PLD 350 is configured to, for example, detect short-circuit or line overcurrent events. In some embodiments, the line current (i... a and i c ) and DC bus current (I dc A proportional voltage signal is compared with a predetermined threshold within the MS-PLD 350 to detect short circuit or line overcurrent events.

[0046] The controller 304 includes a plurality of electrical and electronic components that provide power, operation control, and protection to components and modules within the controller 304 and / or the power tool 100. For example, the controller 304 particularly includes a processing unit 352 (e.g., a microprocessor, microcontroller, electronic processor, electronic controller, or other suitable programmable device), a memory 356, an input unit 360, and an output unit 364. The processing unit 352 particularly includes a control unit 368, an arithmetic logic unit (“ALU”) 372, and a plurality of registers 376 (in... Figure 3 The system is shown as a set of registers and is implemented using a known computer architecture (e.g., a modified Harvard architecture, von Neumann architecture, etc.). Processing unit 352, memory 356, input unit 360, and output unit 364, as well as various modules or circuits connected to controller 304, are connected via one or more control and / or data buses (e.g., common bus 380). For illustrative purposes, in... Figure 3 The control and / or data bus is generally shown in the diagram. Given the inventive features described herein, it is known to those skilled in the art to use one or more control and / or data buses for interconnection and communication between various modules, circuits, and component groups.

[0047] Memory 356 is a non-transitory computer-readable medium, including, for example, a program storage area and a data storage area. The program storage area and data storage area may include combinations 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 devices. Processing unit 352 is connected to memory 356 and executes software instructions that can be stored in RAM of memory 356 (e.g., during execution), ROM of memory 356 (e.g., on a substantially permanent basis), or another non-transitory computer-readable medium (such as another memory or disk). Software included in an implementation of a power tool may be stored in memory 356 of controller 304. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. Controller 304 is configured to retrieve from memory 356 and execute instructions related to the control processes and methods described herein. In other configurations, controller 304 includes additional, fewer, or different components.

[0048] The battery pack interface 312 includes a combination of mechanical components (e.g., rails, recesses, latches, etc.) and electrical components (e.g., one or more terminals) configured and usable for interfacing the power tool 100 with the battery pack (e.g., mechanical, electrical, and communicative connection). For example, power supplied to the power tool by the battery pack is provided to the power input module 340 via the battery pack interface 312. The power input module 340 includes a combination of active and passive components to regulate or control the power received from the battery pack before supplying power to the controller 304. One such component may include a resistive current-sensing shunt configured to convert the output battery current into an analog voltage input to the MS-PLD 350 and the controller 304. The battery pack interface 312 also supplies power to the inverter 348 for operation by a switching FET (e.g., Q...). a+ Q a- Q b+ Q b- Q c+ Q c- Switching to selectively supply power to motor 308.

[0049] The MS-PLD 350 receives a signal corresponding to the inverter / motor line current, and compares the DC bus current with a predetermined threshold internal to the MS-PLD 350 to detect events such as short circuits or line overcurrent. Upon detecting a fault, the MS-PLD 350 signals the controller 304 to notify of the fault. The MS-PLD 350 can be, for example, a simple or complex mixed-signal PLD based on an EPROM, EEPROM, or flash memory.

[0050] Indicator 332 includes, for example, one or more light-emitting diodes (“LEDs”). Indicator 332 can be configured to display the status of the power tool or information associated with the power tool. For example, indicator 332 is configured to indicate the measured electrical characteristics of the power tool, the status of the device, etc. One or more user input modules 336 can be operatively coupled to controller 304 to, for example, select a forward or reverse working mode, set the torque and / or speed of the power tool (e.g., using a torque and / or speed switch), etc. In some embodiments, one or more user input modules 336 may include a combination of digital and analog input or output devices required to implement a desired level of operation of the power tool, such as one or more knobs, one or more dials, one or more switches, one or more buttons, etc. In some embodiments, one or more user input modules 336 can wirelessly receive signals from a device external to the power tool (e.g., a user's mobile phone).

[0051] Controller 304 can be configured to determine whether a fault condition exists in the power tool and generate one or more control signals associated with that fault condition. For example, controller 304 can calculate or include in memory 356 predetermined operating thresholds and limits for power tool operation. For example, when controller 304 or MS-PLD 350 detects or predicts a potential thermal fault or abnormal battery voltage (e.g., in the FET, motor 308, etc.), it can limit or interrupt power to motor 308 until the likelihood of a thermal fault decreases. If controller 304 detects one or more such fault conditions in the power tool or determines that a fault condition no longer exists, controller 304 can be configured to provide information and / or control signals to another component of the power tool (e.g., battery interface 312, indicator 332, etc.). Signals can be configured to, for example, trip or disconnect a fuse, reset switch, etc., of the power tool.

[0052] Figure 4 A block diagram of an sFOC hardware topology 400 for a power tool (e.g., power tool 100) is shown. The sFOC hardware topology 400 is... Figure 3The exemplary implementation of the control system 300 disclosed herein, and the specific implementation including additional filters or any further disclosed sensors, electrical components, controllers or power electronic devices, does not preclude other implementations of the control system 300 and the electrical components disclosed herein.

[0053] The sFOC hardware topology 400 is a single-shunt FOC motor controller specifically designed for use in power tools and outdoor electric equipment operated by battery packs. Hardware topology 400 includes a battery pack or battery 404 that powers a microcontroller 408 (e.g., controller 304) and a motor 420 (e.g., motor 308). Microcontroller 408 is configured to communicate with gate driver 412 to control power switching circuitry 416 (e.g., inverter 348) to drive motor 420. As motor 420 rotates, Hall effect sensor 424 communicates with microcontroller 408, allowing microcontroller 408 to determine the rotational position of motor 420. In some embodiments, a plurality of Hall effect sensors 424 are implemented (e.g., three Hall effect sensors).

[0054] The sFOC hardware topology 400 may also include a plurality of electrical and / or electronic components for sensing, filtering, and processing electrical signals. For example, the hardware topology 400 includes a battery current sensor 428 (e.g., a resistive current sensing shunt), a differential amplifier 430, a resistive voltage divider 432, a DC bus filter 434, a bridge capacitor 436, and a mixed-signal programmable logic device (“MS-PLD”) 444 (e.g., MS-PLD 350). Starting from the battery 404, the DC bus filter 434 is connected in parallel with the battery output and is configured to minimize voltage ripple and power dissipation across the DC bus due to thermal stress on the DC bus. Therefore, the DC bus filter 434 is configured to improve the service life of the power tool. The DC bus filter 434 includes one or more of the following connected in parallel: a solid polymer aluminum electrolytic capacitor, a connected solid hybrid aluminum electrolytic capacitor, a non-solid (wet) aluminum electrolytic capacitor, etc. Select capacitors based on their size, rated voltage, rated ripple current, and equivalent series resistance (ESR) to minimize voltage ripple and power dissipation on the DC bus and provide sufficient operating life under given thermal stress.

[0055] A battery current sensor 428 is located between the DC bus filter 434 and the power switch circuit 416, and is configured to convert the output battery current from the battery 404 into an analog voltage signal for the MS-PLD 444. The voltage across the shunt resistor is proportional to the current flowing through the shunt resistor. Using this voltage, the differential amplifier 430 generates an analog signal (i) representing the sensed bus current. DCThe current signal is then directed to the MS-PLD 444 and the microcontroller 408. The MS-PLD 444 also compares the current signal to a predetermined threshold within the MS-PLD 444. In some embodiments, if the current signal generated by the differential amplifier 430 is greater than or equal to the predetermined threshold, the MS-PLD 444 may determine that a short circuit or line overcurrent (“OC”) event has occurred and transmit the error to the microcontroller 408.

[0056] Power from the DC bus is also supplied to power switching circuit 416, which comprises three (3) half-bridges having a total of six (6) power switches. In some embodiments, the power switches are field-effect transistors (“FETs”), metal-oxide-semiconductor FETs (“MOSFETs”), etc. Power switching circuit 416 is configured to convert the DC voltage from battery 404 into a three-phase voltage with variable amplitude and frequency to drive motor 420. Each half-bridge includes two power switches (e.g., MOSFETs with anti-parallel [trench or body] diodes), wherein the two power switches within a half-bridge are connected in series and correspond to a specific phase of motor 420. In some embodiments, if the power switch current ratings are lower than the required application ratings, the half-bridges can be connected in parallel (e.g., six in an inverter, two per phase), resulting in a twelve-switch inverter. In some embodiments, the power switches may be silicon, silicon carbide (“SiC”), or gallium nitride (“GaN”) based power switches. Bridge capacitor 436 is placed in parallel with the half-bridges of power switching circuit 416. Bridge capacitor 436 helps improve the uniformity of impedance for each phase of motor 420. In some embodiments, bridge capacitor 436 may be a plurality of bridge capacitors, each connected in parallel with a corresponding half-bridge (e.g., corresponding phase) of power switching circuit 416. In such an embodiment, the capacitance of each capacitor in the plurality of bridge capacitors can be reduced to allow current transients to pass through and be measured by battery current sensor 428.

[0057] The microcontroller 408 receives signals from various sensors to control the operation of power tools, monitor power tools, and activate one or more indicators 332 (e.g., LEDs) based on the power tool's status. For example, the voltage across the DC bus (V... dcThe voltage is divided by a resistor divider 432. An attenuated signal is connected to one of the inputs of the analog-to-digital converter (“ADC”) of the microcontroller 408. The microcontroller 408 is configured to compare the signal from the voltage divider 432 with predefined thresholds stored in the microcontroller 408 to provide overvoltage and undervoltage protection (e.g., monitoring the voltage of battery 404). The microcontroller 408 is also configured to process the signal from the voltage divider 432 when controlling the motor 420 to minimize the effects of voltage ripple across the DC bus, and to determine the current trajectory in the case of an MTPV implementation. The microcontroller 408 can also incorporate a signal generated by a Hall effect sensor 424 to control the drive of the motor 420. Specifically, the microcontroller 408 uses the Hall effect sensor 424 to estimate the position and speed of the motor 420. Using the signals from the voltage divider 432, the current sensor 428, and the Hall effect sensor 424, the microcontroller 408 is configured to implement a closed-loop sensed field-oriented control (sFOC) algorithm. For example, microcontroller 408 can use the DC bus current measured by battery current sensor 428 to determine the feedback phase current for field-oriented control. Then, microcontroller 408 can generate switching signals (S) for each half-bridge MOSFET. a+ S a- S b+ S b- S c+ and S c- A switching signal is provided to the gate driver 412 and used to drive the motor 420 at a specific speed and / or torque.

[0058] It is worth noting that, unlike conventional three-phase current FOC, which monitors both battery current and the current of motor 420, Figure 4 The topology 400 shown uses only one (single) shunt resistor and current-sensing amplifier. Therefore, in addition to reducing the amount of hardware required, the control and benefits of FOC are still qualitatively improved. Specifically, topology 400 allows for a more compact power switching circuit 416 and more consistent impedance, and thus allows for more consistent phase readings between each phase of the motor 420.

[0059] Figure 5 A block diagram of a single-shunt-based FOC motor control system 500, employing a sensed field-oriented control (“sFOC”) algorithm implemented by a power tool (e.g., power tool 100), is shown. The control system 500 may be implemented by a controller of the power tool (e.g., controller 304, microcontroller 408, etc.) and may include one or more additional controllers (e.g., dedicated controllers). The control system 500 also includes one or more sensors and components for receiving signals from the sensors. For example, as... Figure 5As shown, the control system 500 includes a battery voltage input block 504, a Hall effect sensor input block 508, and a current input block 512 (e.g., from a battery current sensor 428). Furthermore, in the illustrated embodiment, the control system 500 operates different control sections at different frequencies, including an external input section 506, a position control section 510, and a multisampling section 514. For example, the position control section 510 is connected to the Hall effect sensor input block 508 and operates during the time period of the PWM switching cycle. The external input section 506 is configured to receive commands from the user and therefore operates at a much lower frequency. The multisampling section 514 is configured to receive multiple signals during the PWM switching cycle to allow for dynamic measurement and control. In other words, the position control section 510 can operate at a first frequency, the multisampling section 514 can operate at a second frequency greater than the first frequency, and the external input section 506 can operate at a third frequency lower than the first and second frequencies. In one embodiment, the position control section 510 can operate at a frequency corresponding to the PWM frequency used to control the rotation of a motor (e.g., motor 420), and the multisampling section 514 can operate at a frequency corresponding to a multiple of the PWM frequency (e.g., 2x, 3x, 4x, etc.).

[0060] At block 516, the period of the signal from the Hall effect sensors is measured by determining the time between the rising and falling edges of the three Hall effect sensors to determine the rotor speed (w). r Then, at block 520, the rotor speed (w) is adjusted using a low-pass filter. r ) is filtered to produce a filtered velocity value (w) rf The control system 500 can also receive one or more user inputs. For example, the control system 500 includes a speed command block 524 and a torque command block 528, which are configured to generate speed commands (w, w, and y) based on the user input position (e.g., trigger 230). cmd ) and directional torque command (i dcmd and i qcmd The control system 500 further includes a speed ramp block 532, which is configured to determine a speed reference (ωrref) based on a speed command and a reference acceleration or deceleration. Additionally, the speed ramp block 532 determines an acceleration or deceleration torque (Tacc), which can be used by a speed regulator at block 536 to generate a speed control signal (i). ref In other words, at block 536, the speed regulator is configured to receive a first signal (ω) corresponding to the current angular velocity of the rotor of the motor (e.g., motor 420). rfThe speed regulator is then configured at block 536 to operate based on the current angular velocity (ωrref) and a second signal (ωrref) corresponding to the target angular velocity of the rotor. rf The stator current signal (i) is generated by referencing the target angular velocity (ωrref). ref To control the stator.

[0061] The control system 500 includes a flux weakening block 540 configured to implement a maximum torque per ampere (“MTPA”) algorithm, and in some embodiments, a maximum torque per volt (“MTPV”) algorithm. The flux weakening block 540 is configured to determine the reference direct-axis and quadrature-axis stator currents and the orthogonal-axis stator current (i) when implementing the MTPA or MTPV algorithm with or without flux weakening action. dref and i qref The MTPA algorithm is configured to receive the stator current signal i. ref And generate magnetic flux current signal i dref and torque current signal i qref In some implementations, the MTPA algorithm is configured to determine the MPTA vector (i.e., the vector formed by the components i). d and i q The algorithm checks whether the synthesized vector created from the vector is the smallest current space vector. Additionally, if the MTPA vector is not the smallest current space vector or does not meet predetermined constraints, the MTPA algorithm can recalculate the MPTA vector.

[0062] The MTPV algorithm additionally receives and filters the rotor speed (w) rf ) and DC bus voltage (V dcf Both. In some implementations, the DC bus voltage (V) dcf The signal passes through a filter (e.g., a low-pass filter) before being input to the flux weakening block 540. The MTPV algorithm also receives, for example, a flux current signal i. d And generate torque current signal i q The MTPV algorithm determines a scaling factor based on the angle of the MTPA vector output by the MTPA algorithm. The scaling factor can be between 0 and 1. The algorithm also includes determining the MTPV vector as the product of the MTPA vector and the scaling factor. In some implementations, the scaling factor is 1. In these implementations, the MTPV vector is the same as the MTPA vector. The MTPV algorithm can also determine the negative current based on the MTPV vector. In some implementations, the user can select the output mode of the power tool. Based on the user selection at block 546, the control system 500 can select either a torque mode or a speed mode and adjust the reference current used to control the motor accordingly.

[0063] The control system 500 includes a current sampling block 550 and a current reconstruction block 554. The current sampling block 550 is configured to read the bus current (i) from the ADC at block 512. DC The two samples are arranged to be equal to the two bus components (i) of the two branch currents of the power switch circuit 416. DC x i DC y Then, at block 560, the control system 500 uses a direct Clarke transform to transform the motor currents to decouple and reduce the symmetrical three-phase system to have only two currents (i). α and i β The control system 500 includes a direct Park transform block 564 configured to receive two-phase current signals (i) from the direct Clark transform block 560. α and i β And a signal θ related to the current angular position of the motor rotor is received from a Hall effect sensor (e.g., Hall effect sensor 328). hall The direct Clarke transform block 560 is configured to transform a stationary reference frame into a synchronously rotating reference frame. The direct Parker transform block 564 is further configured to be based on a two-phase current signal i α i β and signal θ hall Generate the first current signal i corresponding to the total torque current of the motor. q and the second current signal i corresponding to the total magnetic flux current of the motor d .

[0064] Reference stator current (i) from flux weakener block 540 dref and i qref The feedforward term (FF) is fed into the current regulator block 568. The current regulator block 568 is configured to calculate the feedforward term (FF) of the current regulator. d and FF q The feedforward term reduces the inherent cross-coupling between the orthogonal and perpendicular axes and enables independent regulation of the two currents. Using the calculated feedforward term FF... d and FF q The current regulator block 568 will determine the flux and torque current signals i in the direct Parker converter block 560. d and i q Oriented toward the corresponding reference current i dref and i qref Adjustments are made to generate reference d-axis and q-axis voltages V. dref and V qrefIn other words, the control system 500 can be configured to regulate the injected stator flux current based on the feedforward term.

[0065] The control system 500 further includes an inverse Parker converter block 572, which is configured to receive a first signal V corresponding to the magnetic flux voltage from the flux controller. d Receive a second signal V corresponding to the torque voltage from the torque controller. q and receiving a signal θ from the Hall sensor corresponding to the current angular position of the motor rotor. hall The inverse Parker transform block 572 can be configured to be based on the signal θ. hall The first signal V d Second signal V q The number V converted to an orthogonal stationary reference frame α and V β Then, the inverse Parker transform block 572 is configured to output the number of orthogonal stationary reference frames V for driving the motor 420. α and V β .

[0066] The control system 500 includes a modulation index calculation block 576, which is configured to determine the modulation index about the stationary reference axis (m). α and m β The modulation index is determined based on the reciprocal (1 / V) of the maximum fundamental stator voltage determined by the inverse Clarke transform block 580. max ) to determine the reference modulation index (m ref In some implementations, the scaling factor of the MTPV algorithm can be determined by the modulation index calculation block 576. In some implementations, the modulation index can be adjusted based on other tool parameters (e.g., temperature, battery life, etc.).

[0067] The three-phase duty cycle analyzer block 584 determines the duty cycle state (DS) by comparing the determined motor phase with the modulation index. abc Duty cycle status (DS) abc This indicates which phase to modify in the PWM pulse shifter block. In some implementations, DS... abc It also guides the three-phase current reconfiguration block.

[0068] The control system 500 includes a three-phase PWM pulse shifter block 588, which is configured to implement or mix various PWM strategies (e.g., third harmonic injection, minimum-maximum, space vector pulse width modulation, discontinuous pulse width modulation, etc.) based on the duty cycle state (DS). abc The drive parameters or duty cycle (PWMa, PWMb, PWMc) of each phase of the motor are calculated using a reference modulation index (m). In some implementations, the PWM strategy or a combination of PWM strategies is used to calculate the drive parameters or duty cycle (PWMa, PWMb, PWMc) of each phase of the motor. refThe stator frequency is determined. For example, if the reference modulation index requires overmodulation (non-linear mode) operation, the control system 500 is configured to perform linearization of the total gain. This block executes twice within one PWM cycle to allow for dual PWM updates. Therefore, two different values ​​are applied to generate the switching signals. Figure 6 As shown, this shift allows two effective voltage vectors to cover the duration of the ADC sampling bus current.

[0069] After determining the duty cycle of each phase of the motor, the duty cycle is converted into a register value at block 592 and compared with a continuous up-and-down counter. At block 592, the control system 500 is configured to use the comparison register value and the counter to generate a drive command or switching signal (S) for controlling the gate driver (e.g., gate driver 412). a+ S a- S b+ S b- S c+ and S c- The gate driver then drives the power switching circuit 416 to drive the motor 420.

[0070] Representative characteristics

[0071] Representative features are described in the following clauses, which may be combined independently or in any combination with one or more features disclosed in the text and / or drawings of this patent specification.

[0072] Article 1. An electric tool comprising: a housing; a battery pack socket disposed on the housing and configured to receive a battery pack; a brushless motor disposed in the housing, the brushless motor including a rotor and a stator, the rotor being coupled to a motor shaft arranged to rotate about a longitudinal axis extending through the motor shaft, the motor shaft being arranged to produce a rotational output to a drive mechanism; one or more position sensors disposed adjacent to the brushless motor and configured to generate an output signal corresponding to a rotational position of the brushless motor; a power switching circuit configured to provide a power supply from the battery pack to the brushless motor; a single current sensor disposed between the battery pack and the brushless motor and configured to determine the power supply from the battery pack to the brushless motor; and an electronic controller connected to the one or more position sensors, the single current sensor, and the power switching circuit, the electronic controller being configured to implement field-oriented control (“FOC”) of the brushless motor.

[0073] Article 2. The power tool according to Article 1 further includes: a mixed-signal programmable logic device electrically connected to the single current sensor, the mixed-signal programmable logic device being configured to detect fault conditions.

[0074] Article 3. The power tool described in Article 2, wherein the fault condition is a short circuit condition.

[0075] Article 4. In any of the preceding articles, the electronic controller is further configured to generate a current command using a speed regulator and output signals from one or more position sensors.

[0076] Article 5. In any of the preceding articles, the power tool wherein the electronic controller is further configured to: determine the rotor speed based on output signals from the one or more position sensors; and generate a current command using a speed regulator, the current command being based on the rotor speed and a target speed.

[0077] Article 6. The power tool according to Article 5, wherein the electronic controller is further configured to: determine operation in torque mode based on user selection; receive torque input commands based on user input; and generate current commands based on the torque input commands.

[0078] Article 7. In any of the preceding articles, the power tool wherein the electronic controller is further configured to determine a first feedforward term and a second feedforward term based on a signal from the single current sensor and an output signal from one or more position sensors, wherein the first feedforward term corresponds to motor speed and the second feedforward term corresponds to motor torque.

[0079] Article 8. In any of the preceding articles, the power tool wherein the controller is further configured to: during a position control section, receive output signals from one or more position sensors, determine parameters of the brushless motor based on the output signals from one or more position sensors; and during a multisampling section, use FOC to determine drive parameters of the motor based on the parameters of the brushless motor, generate a drive command based on the drive parameters, and drive the brushless motor based on the drive command.

[0080] Article 9. The power tool according to Article 8, wherein the position control section operates at a first frequency, and the multisampling section operates at a second frequency greater than the first frequency.

[0081] Article 10. The power tool according to Article 9, wherein the first frequency is a PWM frequency corresponding to the frequency used to control the rotation of the motor, and the second frequency is a multiple of the first frequency.

[0082] Article 11. A power tool according to any of the preceding articles, wherein the electronic controller is further configured to: determine a rotor speed based on output signals from one or more position sensors during a position control section; and generate a current command using a speed regulator during an external input section, the current command being based on the rotor speed and a target speed.

[0083] Article 12. The power tool according to Article 11, wherein the position control section operates at a first frequency, and the external input section operates at a second frequency lower than the first frequency.

[0084] Article 13. A method for controlling a brushless motor of a handheld power tool, the method comprising: during an external input section, generating a current command using a speed regulator and output signals received from one or more position sensors; during a position control section, determining a first feedforward term and a second feedforward term based on signals from the current command and output signals from one or more position sensors, and determining parameters of the brushless motor based on the first feedforward term and the second feedforward term; and during a multisampling section, determining drive parameters of the motor based on the parameters of the brushless motor using field orientation control (“FOC”), generating a drive command based on the drive parameters, and driving the brushless motor based on the drive command.

[0085] Article 14. The method according to Article 13, wherein the first feedforward term corresponds to the motor speed and the second feedforward term corresponds to the motor torque.

[0086] Article 15. The method according to Article 13 or 14, wherein the parameters of the brushless motor include at least one of the rotational position, speed or acceleration of the brushless motor.

[0087] Article 16. The method according to Articles 13, 14 or 15, wherein the parameters of the brushless motor are a plurality of duty cycles for each phase of the motor.

[0088] Article 17. An electric tool, comprising: a housing; a battery pack socket disposed on the housing and configured to receive a battery pack; a brushless motor disposed in the housing, the brushless motor including a rotor and a stator, the rotor being coupled to a motor shaft arranged to rotate about a longitudinal axis extending through the motor shaft, the motor shaft being arranged to produce a rotational output to a drive mechanism; one or more position sensors disposed adjacent to the brushless motor and configured to generate an output signal corresponding to a rotational position of the brushless motor; a power switching circuit configured to provide power from the battery pack to the brushless motor; and a single current sensor disposed between the battery pack and the brushless motor, the single current sensor... A sensor is configured to measure the power supply from the battery pack to the brushless motor; and an electronic controller is configured to implement field-oriented control (“FOC”) of the brushless motor, the electronic controller being configured to: during an external input section, generate a current command using a speed regulator and output signals received from one or more position sensors; during a position control section, determine a first feedforward term and a second feedforward term based on signals from the current command and output signals from the one or more position sensors, and determine parameters of the brushless motor based on the first feedforward term and the second feedforward term; and during a multisampling section, determine drive parameters of the motor using the FOC based on the parameters of the brushless motor, generate a drive command based on the drive parameters, and drive the brushless motor based on the drive command.

[0089] Article 18. The power tool according to Article 17, wherein the position control section operates at a first frequency, and the multisampling section operates at a second frequency greater than the first frequency.

[0090] Article 19. The power tool according to Article 18, wherein the first frequency is a PWM frequency corresponding to the frequency used to control the rotation of the motor, and the second frequency is a multiple of the first frequency.

[0091] Article 20. The power tool according to Article 18 or 19, wherein the external input portion operates at a third frequency lower than the first frequency.

[0092] Therefore, the embodiments described herein provide a system and apparatus for realizing sensed field orientation control on power tools including brushless DC motors. Various features and advantages are set forth in the appended claims.

Claims

1. A power tool, characterized in that, include: case; A battery pack socket is disposed on the housing and configured to receive a battery pack; A brushless motor is disposed in the housing, the brushless motor including a rotor and a stator, the rotor being coupled to a motor shaft arranged to rotate about a longitudinal axis extending through the motor shaft, the motor shaft being arranged to generate a rotational output to a drive mechanism; One or more position sensors are disposed adjacent to the brushless motor, and the one or more position sensors are configured to generate an output signal corresponding to the rotational position of the brushless motor. A power switching circuit configured to supply power from the battery pack to the brushless motor; A single current sensor is disposed between the battery pack and the brushless motor, and the current sensor is configured to measure the power supply from the battery pack to the brushless motor; and An electronic controller connected to one or more position sensors, a single current sensor, and a power switch circuit, the electronic controller being configured to implement field-oriented control of the brushless motor.

2. The power tool as described in claim 1, characterized in that, Further includes: A mixed-signal programmable logic device electrically connected to the single current sensor, the mixed-signal programmable logic device being configured to detect fault conditions.

3. The power tool as described in claim 2, characterized in that, The fault condition described is a short circuit.

4. The power tool as described in claim 1, characterized in that, The electronic controller is further configured to: A current command is generated using a speed regulator and output signals from one or more position sensors.

5. The power tool as described in claim 1, characterized in that, The electronic controller is further configured to: The rotor speed is determined based on the output signals from one or more position sensors; and A current command is generated using a speed regulator, the current command being based on the rotor speed and the target speed.

6. The power tool as described in claim 5, characterized in that, The electronic controller is further configured to: The system operates in torque mode based on user selection. Receive torque input commands based on user input; and A current command is generated based on the torque input command.

7. The power tool as claimed in claim 1, characterized in that, The electronic controller is configured to: The first feedforward term and the second feedforward term are determined based on the signal from the single current sensor and the output signal from one or more position sensors. Wherein, the first feedforward term corresponds to the motor speed, and the second feedforward term corresponds to the motor torque.

8. The power tool as claimed in claim 1, characterized in that, The electronic controller is further configured to: During the position control section Receive the output signal from one or more position sensors, and The parameters of the brushless motor are determined based on the output signals from one or more position sensors; and During the multi-sampling phase, Field-oriented control is used to determine the drive parameters of the brushless motor based on its parameters. Based on the aforementioned driver parameters, driver commands are generated, and The brushless motor is driven based on the drive command.

9. The power tool as claimed in claim 8, characterized in that, The position control section operates at a first frequency, and the multisampling section operates at a second frequency greater than the first frequency.

10. The power tool as claimed in claim 9, characterized in that, The first frequency is a PWM frequency corresponding to the frequency used to control the rotation of the motor, and the second frequency is a multiple of the first frequency.

11. The power tool as claimed in claim 1, characterized in that, The electronic controller is further configured to: During the position control section, the rotor speed is determined based on the output signals from one or more position sensors; and During the external input phase, a current command is generated using a speed regulator, the current command being based on the rotor speed and the target speed.

12. The power tool as claimed in claim 11, characterized in that, The position control section operates at a first frequency, and the external input section operates at a second frequency lower than the first frequency.

13. A power tool, characterized in that, include: case; A battery pack socket is disposed on the housing and configured to receive a battery pack; A brushless motor is disposed in the housing, the brushless motor including a rotor and a stator, the rotor being coupled to a motor shaft arranged to rotate about a longitudinal axis extending through the motor shaft, the motor shaft being arranged to generate a rotational output to a drive mechanism; One or more position sensors are disposed adjacent to the brushless motor, and the one or more position sensors are configured to generate an output signal corresponding to the rotational position of the brushless motor. A power switching circuit configured to supply power from the battery pack to the brushless motor; A single current sensor is disposed between the battery pack and the brushless motor, and the single current sensor is configured to measure the power supply from the battery pack to the brushless motor; and An electronic controller, configured to perform field orientation control of the brushless motor, is configured to: During the external input section A current command is generated using a speed regulator and output signals received from one or more position sensors. During the position control section The first feedforward term and the second feedforward term are determined based on the signal from the current command and the output signals from the one or more position sensors, and The parameters of the brushless motor are determined based on the first feedforward term and the second feedforward term; and During the multi-sampling phase, Field-oriented control is used to determine the drive parameters of the brushless motor based on its parameters. Based on the aforementioned driver parameters, driver commands are generated, and The brushless motor is driven based on the drive command.

14. The power tool as claimed in claim 13, characterized in that, The position control section operates at a first frequency, and the multisampling section operates at a second frequency greater than the first frequency.

15. The power tool as claimed in claim 14, characterized in that, The first frequency is a PWM frequency corresponding to the frequency used to control the rotation of the motor, and the second frequency is a multiple of the first frequency.

16. The power tool as claimed in claim 14, characterized in that, The external input section operates at a third frequency, which is lower than the first frequency.

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