Power tool

Abstract

A power tool includes a permanent magnet assisted synchronous rotor motor. The motor includes a stator and a rotor. The rotor includes a first slot between outer peripheral surfaces of the rotor. The first slot includes a first magnet housing portion. The first magnet housing portion is positioned a first radial distance from a center of rotation of the rotor. The rotor includes a second slot between the outer peripheral surfaces of the rotor and the first slot. The second slot includes a second magnet housing portion. A second length of the second slot is shorter than a first length of the first slot, and the second magnet housing is positioned a second radial distance from the center of rotation of the rotor.

Description

[0001] Related applications

[0002] This application claims the benefit of U.S. Provisional Patent Application No. 63 / 370,197, filed August 2, 2022, and U.S. Provisional Patent Application No. 63 / 503,516, filed May 22, 2023, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The embodiments described in this utility model relate to motors for power tools. Utility Model Content

[0004] The power tool of this invention includes a battery pack interface configured to receive a removable and rechargeable battery pack and a permanent magnet assisted synchronous rotor motor. The motor includes a stator and a rotor. The stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first slot located between the outer peripheral surfaces of the rotor. The first slot includes a first magnet housing portion. The first magnet housing portion has a first width and a first length. The first magnet housing portion is positioned at a first radial distance from the rotation center of the rotor. The rotor includes a second slot located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion. The second magnet housing portion has a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a second radial distance from the rotation center of the rotor. The rotor includes a first magnet within the first magnet housing portion. The first magnet has a first magnet length and a first magnet width. The rotor includes a second magnet within the second magnet housing. The second magnet has a second magnet length and a second magnet width. The first magnet fills at least 60% of the first magnet housing portion, and the second magnet fills at least 60% of the second magnet housing portion. The degree to which the first magnet fills the first magnet housing portion is at least the same as the degree to which the second magnet fills the second magnet housing portion.

[0005] In some embodiments, the stator includes at least twelve stator slots, and the rotor includes at least four rotor poles.

[0006] In some embodiments, the first magnet is made of a ferrite metal material, and the second magnet is made of a rare earth metal material.

[0007] In some embodiments, the percentage by which the second magnet fills the second magnet housing portion is greater than the percentage by which the first magnet fills the first magnet housing portion.

[0008] In some embodiments, the power tool further includes a first steel rib associated with a first slot; and a second steel rib associated with a second slot.

[0009] The power tool of this invention includes a battery pack interface configured to receive a removable and rechargeable battery pack, and a permanent magnet assisted synchronous rotor motor including a stator and a rotor. The stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first slot located between the outer peripheral surfaces of the rotor and a second slot located between the outer peripheral surfaces of the rotor and the first slot. The first slot includes a first magnet housing portion having a first width and a first length, and is positioned at a first radial distance from the rotation center of the rotor. The second slot includes a second magnet housing portion having a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a second radial distance from the rotation center of the rotor. The rotor further includes a first magnet and a second magnet, the first magnet being within a first magnet housing portion, the first magnet having a first magnet length and a first magnet width, and the second magnet being within a second magnet housing, the second magnet having a second magnet length and a second magnet width, wherein the first magnet fills between 60% and 90% of the first magnet housing portion and the second magnet fills between 60% and 90% of the second magnet housing portion, and wherein the degree to which the first magnet fills the first magnet housing portion is at least as much as the degree to which the second magnet fills the second magnet housing portion.

[0010] In some implementations, the stator includes at least eighteen stator slots, and the rotor includes at least six rotor poles.

[0011] In some implementations, the stator includes at least six stator slots, and the rotor includes at least four rotor poles.

[0012] In some embodiments, the first magnet is made of a ferrite metal material, and the second magnet is made of a rare earth metal material.

[0013] In some embodiments, the first magnet and the second magnet are made of rare earth metal materials.

[0014] In some embodiments, the percentage by which the second magnet fills the second magnet housing portion is greater than the percentage by which the first magnet fills the first magnet housing portion.

[0015] The power tool of this invention includes a battery pack interface configured to receive a removable and rechargeable battery pack and a permanent magnet assisted synchronous rotor motor including a stator and a rotor. The stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first slot located between the outer peripheral surfaces of the rotor and a second slot located between the outer peripheral surfaces of the rotor and the first slot. The first slot includes a first magnet housing portion having a first width and a first length, and is positioned at a first radial distance from the rotation center of the rotor. The second slot includes a second magnet housing portion having a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a second radial distance from the rotation center of the rotor. The rotor further includes a first magnet, a second magnet, a first steel rib, and a second steel rib. The first magnet is located within a first magnet housing portion and has a first magnet length and a first magnet width. The second magnet is located within a second magnet housing and has a second magnet length and a second magnet width. The first steel rib is configured to fill a portion of the first magnet housing portion, and the second steel rib is configured to fill a portion of the second magnet housing portion. The first magnet fills at least 60% of the first magnet housing portion, and the second magnet fills at least 60% of the second magnet housing portion. The degree to which the first magnet fills the first magnet housing portion is at least as much as the degree to which the second magnet fills the second magnet housing portion.

[0016] In some embodiments, the first steel rib is positioned at the center of the first magnet housing portion, and the second steel rib is positioned at the center of the second magnet housing portion.

[0017] In some embodiments, the power tool further includes a third steel rib and a fourth steel rib.

[0018] In some embodiments, a first steel rib is configured to be positioned between a first arm of the first slot and a first magnet housing portion, a second steel rib is configured to be positioned between a second arm of the first slot and a first magnet housing portion, a third steel rib is configured to be positioned between a first arm of the second slot and a second magnet housing portion, and a fourth steel rib is configured to be positioned between a second arm of the second slot and a second magnet housing portion.

[0019] The power tool of this invention includes a battery pack interface configured to receive a removable and rechargeable battery pack and a permanent magnet assisted synchronous rotor motor including a stator and a rotor. The stator includes a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes a first radial distance from the rotor's rotation center, a first slot, and a first magnet. The first radial distance is not greater than 90% of the radius of the stator's outer diameter. The first slot is located between the outer peripheral surfaces of the rotor and includes a first magnet housing portion having a first width and a first length. The first magnet housing portion is positioned at a second radial distance from the rotor's rotation center. The rotor further includes a second slot and a second magnet. The second slot is located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion having a second width and a second length. The second length of the second slot is shorter than the first length of the first slot. The second magnet housing is positioned at a third radial distance from the rotation center of the rotor. The first magnet is located within the first magnet housing portion and has a first magnet length and a first magnet width. The second magnet is located within the second magnet housing and has a second magnet length and a second magnet width. The first magnet fills between 30% and 90% of the first magnet housing portion, and the second magnet fills between 30% and 90% of the second magnet housing portion. The second radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance, and the third radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance. The second radial distance is greater than the third radial distance.

[0020] In some embodiments, the first length is between approximately twice the air gap thickness and 50% of the first radial distance, and the first width is between approximately 2.5% and 200% of the width of the magnet housing, and the second width is between 0.5 and 10 times the air gap thickness.

[0021] In some embodiments, the first magnet fills 90% of the first magnet housing portion and the second magnet fills 90% of the second magnet housing portion.

[0022] The power tool of this invention includes a battery pack interface configured to receive a removable and rechargeable battery pack and a permanent magnet assisted synchronous rotor motor. The permanent magnet assisted synchronous rotor motor includes a stator and a rotor. The stator includes an inner diameter and a plurality of stator teeth configured to receive a plurality of stator coils. The rotor includes an air gap thickness comprising the distance between the rotor's outer diameter and the stator's inner diameter, a first slot, the first slot including a first arm, a second arm, and a first magnet housing portion positioned therebetween. The first arm includes a first length between twice the air gap thickness and 50% of the rotor's radial distance, and a first width between 2.5% and 200% of the width of the first magnet housing portion. The second arm includes a second length between twice the air gap thickness and 50% of the rotor's radial distance, and a second width between 2.5% and 200% of the width of the first magnet housing portion.

[0023] In some embodiments, the rotor further includes a second slot comprising a third arm, a fourth arm, and a second magnet housing portion positioned therebetween, wherein the third arm comprises a third length between twice the air gap thickness and 50% of the rotor radial distance, and a third width between 2.5% and 200% of the width of the second magnet housing portion, and wherein the fourth arm comprises a fourth length between twice the air gap thickness and 50% of the rotor radial distance, and a fourth width between 2.5% and 200% of the width of the second magnet housing portion.

[0024] In some embodiments, the stator further includes a diameter of approximately 80 mm. In some embodiments, the rechargeable battery pack includes a maximum voltage of approximately 83.5 volts.

[0025] In some embodiments, the stator further includes stator slot filler for stator windings, wherein the stator slot filler fills about 42% of the stator windings.

[0026] In some embodiments, the permanent magnet assisted synchronous rotor motor further includes phase windings with resistance between 0.11 ohms and 0.15 ohms.

[0027] In some embodiments, the rotor further includes a first magnet within a first magnet housing portion and a second magnet within a second magnet housing, the first magnet being made of a ferrite metal material and the second magnet being made of a rare earth metal material.

[0028] In some implementations, the stator includes at least eighteen stator slots, and the rotor includes at least six rotor poles.

[0029] In some implementations, the stator includes at least six stator slots, and the rotor includes at least four rotor poles.

[0030] The power tool of this invention includes a battery pack interface and a permanent magnet assisted synchronous rotor motor including a stator. The battery pack interface is configured to receive a removable and rechargeable battery pack. The stator includes a plurality of stator teeth, a plurality of stator winding slots, and a plurality of stator windings. The plurality of stator teeth are configured to receive a plurality of stator coils. The plurality of stator winding slots include an outer stator winding periphery and an inner stator winding periphery that are offset from each other by the stator winding radius. The plurality of stator windings are configured to be wound around one or more of the plurality of stator teeth. The power tool further includes a rotor, the rotor including a first radial distance from the rotor's rotation center, a first slot, and a first magnet, the first radial distance being no greater than 90% of the radius of the stator's outer diameter, the first slot being located between the outer peripheral surfaces of the rotor, the first slot including a first magnet housing portion having a first width and a first length, the first magnet housing portion being positioned at a second radial distance from the rotor's rotation center, the first magnet being within the first magnet housing portion, wherein the first magnet fills between 80% and 100% of the first magnet housing portion.

[0031] In some implementations, the outer diameter of the motor is between 60 mm and 65 mm.

[0032] In some implementations, the outer diameter of the motor is 63 mm.

[0033] In some implementations, a plurality of stator windings are configured as distributed windings.

[0034] In some implementations, a plurality of stator windings are configured as concentrated windings.

[0035] In some implementations, a plurality of stator windings are configured to be evenly distributed around the periphery of the stator core.

[0036] In some implementations, a plurality of stator windings are configured to be distributed to reduce harmonic distortion within the permanent magnet assisted synchronous rotor motor.

[0037] In some implementations, a plurality of stator windings are configured to be distributed to provide a uniform distribution of magnetic flux.

[0038] In some embodiments, the rotor further includes a second slot located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion having a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a third radial distance from the rotation center of the rotor. The second magnet is located within the first magnet housing portion, wherein the second magnet fills between 80% and 100% of the first magnet housing portion. The second radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance, and the third radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance. The second radial distance is greater than the third radial distance.

[0039] In some embodiments, a first magnet fills approximately 100% of a first magnet housing portion, and a second magnet fills approximately 100% of a second magnet housing portion.

[0040] In some embodiments, the first magnet is made of a ferrite metal material, and the second magnet is made of a rare earth metal material.

[0041] In some embodiments, the first slot further includes a first arm, a second arm, and a first magnet housing portion positioned therebetween, wherein the first arm includes a first length between twice the air gap thickness and 50% of the rotor radial distance and a first width between 2.5% and 200% of the width of the first magnet housing portion, and the second arm includes a second length between twice the air gap thickness and 50% of the rotor radial distance and a second width between 2.5% and 200% of the width of the first magnet housing portion.

[0042] In some embodiments, the second slot further includes a third arm, a fourth arm, and a second magnet housing portion positioned therebetween, wherein the third arm includes a third length between twice the air gap thickness and 50% of the rotor radial distance and a third width between 2.5% and 200% of the width of the second magnet housing portion, and wherein the fourth arm includes a fourth length between twice the air gap thickness and 50% of the rotor radial distance and a fourth width between 2.5% and 200% of the width of the second magnet housing portion.

[0043] Before explaining any implementation in detail, it should be understood that the implementation is not limited in application to the details of the configuration and arrangement of the components described in the following description or shown in the drawings. The implementation can be practiced or implemented in various ways. Furthermore, it should be understood that the wording and terminology used in this invention are for illustrative purposes and should not be considered restrictive. The use of “comprising,” “including,” or “having,” and variations thereof is intended to cover the items listed thereafter and their equivalents and additional items. Unless otherwise specified or limited, the terms “mounted,” “connected,” “supported,” and “coupled,” and variations thereof are used broadly and cover direct and indirect mounting, connection, support, and coupling.

[0044] 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.

[0045] 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) that can be executed 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.

[0046] Related terms used in conjunction with quantities or conditions, such as “about,” “approximately,” “generally,” etc., will be understood by a person skilled in the art to include the stated value and have a meaning prescribed by the context (e.g., the term includes at least the degree of error associated with measurement accuracy, tolerances 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, an expression such as “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%).

[0047] It should be understood that although some figures show hardware and software located within a particular device, these are for illustrative purposes only. Functions described in this invention as being performed by a single component can be performed by a plurality of components in a distributed manner. Similarly, functions performed by a plurality of components can be combined and performed by a single component. In some embodiments, the components shown can be combined or divided into separate software, firmware, and / or hardware. For example, logic and processing can be distributed among a plurality of electronic processors, rather than being located within a single electronic processor and 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.

[0048] 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 the claimed element should be interpreted as referring to one or more such elements, any one of which is configured, for example, to enable any one or more of the multiple functions, such that one or more elements together perform multiple functions.

[0049] Other aspects of the implementation will become apparent upon careful reading of the detailed description and accompanying drawings. Attached Figure Description

[0050] Figure 1 A side view of a power tool according to some embodiments is shown.

[0051] Figure 2 The following are illustrated according to some embodiments. Figure 1A block diagram of the control system of a power tool.

[0052] Figure 3 The diagram illustrates the relationship with some implementation methods. Figure 1 A battery pack used in conjunction with power tools.

[0053] Figure 4 The following are illustrated according to some embodiments. Figure 3 A block diagram of the control system for the battery pack.

[0054] Figure 5 An internal permanent magnet motor according to some embodiments is shown.

[0055] Figure 6 A permanent magnet assisted synchronous reluctance motor according to some embodiments is shown.

[0056] Figure 7 A permanent magnet assisted synchronous reluctance motor according to some embodiments is shown.

[0057] Figure 8 A permanent magnet assisted synchronous reluctance motor comprising magnets made of two different materials is shown according to some embodiments.

[0058] Figure 9A It is a graphical representation of the efficiency, current, and speed operating curves of various motors according to some implementation methods.

[0059] Figure 9B It is a graphical representation of the efficiency, current, and speed operating curves of various motors according to some implementation methods.

[0060] Figure 10 A surface-mounted permanent magnet motor according to some embodiments is shown.

[0061] Figure 11 A permanent magnet assisted synchronous reluctance motor according to some embodiments is shown.

[0062] Figure 12 A permanent magnet assisted synchronous reluctance motor according to some embodiments is shown.

[0063] Figure 13 A permanent magnet assisted synchronous reluctance motor comprising magnets made of two different materials is shown according to some embodiments.

[0064] Figure 14 It is a graphical representation of the efficiency, current, and speed operating curves of various motors according to some implementation methods.

[0065] Figure 15 An internal permanent magnet motor according to some embodiments is shown.

[0066] Figure 16 A permanent magnet assisted synchronous reluctance motor according to some embodiments is shown.

[0067] Figure 17 A permanent magnet assisted synchronous reluctance motor comprising magnets made of two different materials is shown according to some embodiments.

[0068] Figure 18 It is a graphical representation of the efficiency, current, and speed operating curves of various motors according to some implementation methods.

[0069] Figure 19 A ribbed permanent magnet assisted synchronous reluctance motor is shown according to some embodiments.

[0070] Figure 20 A ribbed permanent magnet assisted synchronous reluctance motor is shown according to some embodiments.

[0071] Figure 21 An internal permanent magnet motor according to some embodiments is shown.

[0072] Figure 22 A permanent magnet assisted synchronous reluctance motor including distributed windings is shown according to some embodiments.

[0073] Figure 23 A permanent magnet assisted synchronous reluctance motor including a centralized winding is shown according to some embodiments.

[0074] Figure 24 It is a graphical representation of the efficiency, current, speed, and output power operating curves of various motors according to some implementation methods. Detailed Implementation

[0075] Figure 1 A power tool 100 including a permanent magnet assisted synchronous reluctance motor is shown. The power tool 100 is, for example, a hammer drill including a housing 102. The housing 102 includes a handle portion 104 and a motor housing portion 106. The power tool 100 further includes an output driver 108 (shown as a chuck), a trigger 110, and a battery pack interface 112. The battery pack interface 112 is configured to connect to or receive a power tool battery pack mechanically and electrically. Although... Figure 1 A hammer drill is shown, but in some embodiments, the components described herein are incorporated into other types of power tools, including drill drives, impact drives, impact wrenches, angle grinders, circular saws, reciprocating saws, flat compactors, core drills, rope trimmers, leaf blowers, vacuum cleaners, etc. In permanent magnet assisted synchronous reluctance motor power tools such as power tool 100, switching elements are selectively enabled and disabled by control signals from a controller to selectively apply power from a power source (e.g., a battery pack) to drive the permanent magnet assisted synchronous reluctance motor.

[0076] Figure 2 A control system 200 for a power tool 100 is shown. The control system 200 includes a controller 202. The controller 202 is electrically and / or communicatively connected to various modules or components of the power tool 100. For example, the controller 202 is electrically connected to a motor 204, a battery interface 206, a trigger switch 208 (connected to trigger 210), one or more sensors or sensing circuits 212, one or more indicators 214, a user input module 216, a power input module 218, an inverter bridge or FET switching module 220 (e.g., including multiple switching FETs), and a gate driver 224 for driving the FET switching module 220. In some embodiments, the motor 204 is a permanent magnet assisted synchronous reluctance motor. The controller 202 includes a combination of hardware and software operable to control the operation of the power tool 100, monitor the operation of the power tool 100, activate one or more indicators 214 (e.g., LEDs), etc.

[0077] The controller 202 includes a plurality of electrical and electronic components that provide power, operation control, and protection to components and modules within the controller 202 and / or the power tool 100. For example, the controller 202 particularly includes a processing unit 226 (e.g., a microprocessor, microcontroller, electronic controller, electronic processor, or other suitable programmable device), a memory 228, an input unit 230, and an output unit 232. The processing unit 226 particularly includes a control unit 234, an arithmetic logic unit (“ALU”) 236, and a plurality of registers 238, and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 226, the memory 228, the input unit 230, and the output unit 232, as well as various modules or circuits connected to the controller 202, are connected via one or more control and / or data buses (e.g., a common bus 240). For illustrative purposes, Figure 2 The diagram generally illustrates the control and / or data bus. In view of the inventive features described herein, the use of one or more control and / or data buses for interconnection and communication between various modules, circuits, and components will be known to those skilled in the art.

[0078] Memory 228 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 226 is connected to memory 228 and executes software instructions that can be stored in RAM of memory 228 (e.g., during execution), ROM of memory 228 (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 power tool 100 may be stored in memory 228 of controller 400. Software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. Controller 202 is configured to retrieve from memory 228 and execute instructions related to the control processes and methods described herein. In other configurations, controller 202 includes additional, fewer, or different components.

[0079] Battery pack interface 206 includes a combination of mechanical components (e.g., rails, recesses, latches, etc.) and electrical components (e.g., one or more terminals) configured and operable for mating with a battery pack (e.g., mechanical, electrical, and communicative connection). For example, it is provided by battery pack 300 (see...). Figure 3 Power supplied to the power tool 100 is provided to the power input module 218 via the battery pack interface 206. The power input module 218 includes a combination of active and passive components to regulate or control the power received from the battery pack 300 before supplying power to the controller 202. The battery pack interface 206 also supplies power to the FET switching module 220 to selectively supply power to the motor 204 by switching the FETs. The battery pack interface 206 also includes, for example, a communication line 242 for providing a communication line or link between the controller 202 and the battery pack 300.

[0080] Sensor 212 includes one or more current sensors, one or more speed sensors, one or more Hall effect sensors, one or more temperature sensors, etc. Indicator 214 includes, for example, one or more light-emitting diodes (“LEDs”). Indicator 214 can be configured to display the status of power tool 100 or information associated with power tool 100. For example, indicator 214 is configured to indicate measured electrical characteristics of power tool 100, the status of power tool, the status of motor 204, etc. User input module 216 is operatively coupled to controller 202 to, for example, select a forward or reverse operating mode, torque and / or speed settings for power tool 100 (e.g., using a torque and / or speed switch), etc. In some embodiments, user input module 216 includes a combination of digital and analog input or output devices required to achieve a desired level of operation of power tool 100, such as one or more knobs, one or more dials, one or more switches, one or more buttons, etc.

[0081] Figure 3 A battery pack 300 is shown. The battery pack 300 includes a housing 302 and an interface portion 304 for connecting the battery pack 300 to a power tool such as the power tool 100.

[0082] Figure 4 A control system for a battery pack 300 is shown. The control system includes a controller 400. The controller 400 is electrically and / or communicatively connected to various modules or components of the battery pack 300. For example, the controller 400 shown is connected to one or more battery cells 402 and an interface 404 (e.g., Figure 3 The interface portion 304 of the battery pack 300 is shown. The controller 400 is also connected to one or more voltage sensors or voltage sensing circuits 406, one or more current sensors or current sensing circuits 408, and one or more temperature sensors or temperature sensing circuits 410. The controller 400 includes a combination of hardware and software operable to control the operation of the battery pack 300, monitor the status of the battery pack 300, enable or disable the charging of the battery pack 300, enable or disable the discharging of the battery pack 300, etc.

[0083] The controller 400 includes a plurality of electrical and electronic components that provide power, operational control, and protection to components and modules within the controller 400 and / or battery pack 300. For example, the controller 400 particularly includes a processing unit 412 (e.g., a microprocessor, microcontroller, electronic processor, electronic controller, or other suitable programmable device), a memory 414, an input unit 416, and an output unit 418. The processing unit 412 particularly includes a control unit 420, an ALU 422, and a plurality of registers 424, and is implemented using a known computer architecture (e.g., a modified Harvard architecture, a von Neumann architecture, etc.). The processing unit 412, memory 414, input unit 416, and output unit 418, as well as various modules or circuits connected to the controller 400, are connected via one or more control and / or data buses (e.g., a common bus 426). For illustrative purposes, Figure 4 The diagram generally illustrates the control and / or data bus. In view of the inventive features described herein, the use of one or more control and / or data buses for interconnection and communication between various modules, circuits, and components will be known to those skilled in the art.

[0084] Memory 414 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 412 is connected to memory 414 and executes software instructions that can be stored in RAM of memory 414 (e.g., during execution), ROM of memory 414 (e.g., on a substantially permanent basis), or another non-transitory computer-readable medium (such as another memory or disk). Software included in the implementation of battery pack 300 may be stored in memory 414 of controller 400. Software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. Controller 400 is configured to retrieve from memory 414 and execute instructions related to the control processes and methods described herein. In other configurations, controller 400 includes additional, fewer, or different components.

[0085] Interface 404 includes a combination of mechanical components (e.g., guide rails, grooves, latches, etc.) and electrical components (e.g., one or more terminals), configured and operable to interface (e.g., mechanically, electrically, and communicatively) the battery pack 300 with another device (e.g., a power tool, a battery charger, etc.). For example, interface 404 is configured to communicatively connect to controller 400 via communication line 428.

[0086] Figure 5 An internal permanent magnet motor 500 is shown. The internal permanent magnet motor 500 includes a stator 505 and a plurality of stator winding slots 510. The plurality of stator winding slots 510 are configured to receive a plurality of windings 515. The internal permanent magnet motor 500 includes a rotor 517. The rotor 517 includes a circumferential outer surface 540 spaced from a rotation center of the rotor 517 by a first radial distance 542. The rotor 517 also includes a plurality of slots 535 configured to receive magnets. In some embodiments, a slot 535 includes a first arm 520 and a second arm 521, and a magnet housing portion 522 of the slot located therebetween. The magnet housing portion 522 is configured to spaced from the rotation center of the rotor 517 by a second radial distance 545. The magnet housing portion 522 is configured to receive a magnet 524 having a length 525 and a width 530. In some embodiments, the magnet 524 has a length 525 that fills approximately 100% of the magnet housing portion 522.

[0087] Figure 6 A permanent magnet assisted synchronous reluctance motor 600 according to some embodiments is shown. The motor 600 includes a stator 605 and a plurality of stator winding slots 610. The stator 605 includes a plurality of stator teeth 606. The plurality of stator teeth includes a stator tooth width 607 and a stator tooth length 608. The plurality of stator winding slots 610 are configured to receive a plurality of windings 615. The motor 600 includes a rotor 617. The rotor 617 includes a first slot 620 and a second slot 625. The first slot 620 includes a first arm 621 and a second arm 622, and a first magnet housing portion 623 positioned therebetween. The second slot 625 includes a first arm 626 and a second arm 627, and a second magnet housing portion 628 positioned therebetween. The motor 600 may include pairs of first and second slots for each pole (e.g., four poles, six poles, etc.) of the rotor 617.

[0088] The rotor 617 includes a circumferential outer surface 618 spaced from the rotor's rotation center by a first radial distance 619. In some embodiments, the first radial distance 619 is no greater than 90% of the radius of the stator outer diameter. The first arm 621 of the first slot 620 includes a first width 634 and a first length 630. In some embodiments, the first width 634 is between 2.5% and 200% of the first width 650 of the first magnet housing portion 623, and the first length 630 is between 1 mm and 50% of the first radial distance 619. The first magnet housing portion 623 includes a first width 650 and a first length 635. In some embodiments, the first width 650 is between 0.5 and 10 times the air gap thickness, and the first length 635 is greater than the stator tooth width 607. The air gap thickness is the distance between the rotor outer diameter 651 and the stator inner diameter 652. For example, in some embodiments, the first width 650 is twice the air gap thickness. The first arm 626 of the second slot 625 includes a first width 633 and a first length 632. The second magnet housing portion 628 includes a first length 640 and a first width 645. In some embodiments, the first width 633 is between 2.5% and 200% of the first width 645, and the first length 632 is between twice the air gap thickness and 50% of the first radial distance 619. In some embodiments, the first width 645 is between 0.5 and 10 times the air gap thickness, and the first length 640 is greater than the stator tooth width 607.

[0089] In some embodiments, the first slot 620 is referred to as the outer slot, and the second slot 625 is referred to as the inner slot. In some embodiments, the first slot 620 and the second slot 625 are positioned at different radial distances from the rotation center of the rotor 617. For example, the first slot 620 is positioned at a second radial distance 655 from the rotation center of the rotor 617. In some embodiments, the second radial distance 655 is not greater than 50% to 95% of the first radial distance 619, and the second slot 625 is positioned at a third radial distance 660 from the rotation center. In some embodiments, the third radial distance is between 50% and 95% of the first radial distance 619, wherein the second radial distance 655 is greater than the third radial distance 660.

[0090] A first magnet housing portion 623 is configured to receive a magnet, such as magnet 665. In some embodiments, magnet 665 is configured to fill approximately 80% to 100% of the first magnet housing portion 623. A second magnet housing portion 628 is configured to receive a magnet, such as magnet 670. In some embodiments, magnet 670 is configured to fill approximately 100% of the second magnet housing portion 628. In some embodiments, magnets 665 and 670 are rare-earth magnets (e.g., neodymium magnets).

[0091] Figure 7 A permanent magnet assisted synchronous reluctance motor 700 according to some embodiments is shown. The motor 700 includes a stator 705 and a plurality of stator winding slots 710. In some embodiments, the stator 705 is configured to include at least twelve stator slots. The stator 705 includes a plurality of stator teeth 706. The plurality of stator teeth includes a stator tooth width 707 and a stator tooth length 708. The plurality of stator winding slots 710 are configured to receive a plurality of windings 715. The motor 700 includes a rotor 717. The rotor 717 includes a circumferential outer surface 718 spaced from the rotation center of the rotor 717 by a first radial distance 719. The first radial distance 719 is not greater than 90% of the radius of the stator outer diameter of the stator 705. The rotor 717 includes a first slot 720 and a second slot 725. The first slot 720 includes a first arm 721 and a second arm 722, and a first magnet housing portion 723 is positioned between the first arm 721 and the second arm 722. The second slot 725 includes a first arm 726 and a second arm 727, and a second magnet housing portion 728 is positioned between the first arm 726 and the second arm 727. The motor 700 may include a pair of first and second slots for each pole (e.g., four poles, six poles, etc.) of the rotor 717.

[0092] The first arm 721 and the second arm 722 of the first slot 720 have a first length 745 and a first width 750. The first magnet housing portion 723 has a first magnet housing portion length 775 and a first magnet housing portion width 776. In some embodiments, the first length 745 is between twice the air gap thickness and 50% of the first radial distance 719, and the first width 750 is between 0.5 and 10 times the air gap thickness. The air gap thickness is the distance between the rotor outer diameter 751 and the stator inner diameter 752. For example, in some embodiments, the first length 745 is twice the air gap thickness. In some embodiments, the first magnet housing portion width 776 is between 0.5 and 10 times the air gap thickness. In some embodiments, the first magnet housing portion length 775 is greater than the stator tooth width 707. In some embodiments, the first magnet housing portion 723 has a corresponding magnet fill degree or magnet fill percentage.

[0093] The first arm 726 and the second arm 727 of the second slot 725 have a first length 730 and a first width 735. In some embodiments, the first length 730 is twice the air gap thickness and 50% of the first radial distance 719, and the first width 735 is between 2.5% and 200% of the width 781 of the second magnet housing portion. The second magnet housing portion 728 has a second magnet housing portion length 780 and a second magnet housing portion width 781. In some embodiments, the width 781 of the second magnet housing portion is between 0.5 and 10 times the air gap thickness. In some embodiments, the length 780 of the second magnet housing portion is greater than the stator tooth width 707. In some embodiments, the second magnet housing portion 728 has a corresponding magnet filling degree or magnet filling percentage.

[0094] The first magnet housing portion 723 is configured to receive a magnet. In some embodiments, a magnet, such as magnet 755, fills at least 30% of the first magnet housing portion 723 (e.g., 30% of the length 775 of the first magnet housing portion). In some embodiments, magnet 755 has a length 770 that is less than the total length of the length 775 of the first magnet housing portion. In some embodiments, magnet 755 fills between 60% and 90% of the first magnet housing portion 723.

[0095] The second magnet housing portion 728 is configured to receive a magnet, such as magnet 760. In some embodiments, similar to the first magnet housing portion 723, the second magnet housing portion 728 is configured to receive a magnet that fills at least 30% of the second magnet housing portion 728 (e.g., 30% of the length 780 of the second magnet housing portion). In some embodiments, magnet 760 has a length 765 that is less than the length of the second magnet housing portion 780. In some embodiments, magnet 760 fills the second magnet housing portion 728 to at least the same extent as magnet 760 fills the first magnet housing portion 723. For example, magnet 755 corresponds to a greater percentage of the first magnet housing portion 723 than magnet 760 fills the second magnet housing portion 728. In some embodiments, magnet 760 fills between 30% and 90% of the second magnet housing portion 728. In some embodiments, magnets 755 and 760 are rare-earth magnets (e.g., neodymium magnets).

[0096] In some embodiments, the first slot 720 is referred to as the outer slot, and the second slot 725 is referred to as the inner slot. In some embodiments, the first slot 720 and the second slot 725 are located at different radial distances from the rotation center of the rotor 717. For example, the first slot 720 is located at a second radial distance 785 from the rotation center of the rotor 717. In some embodiments, the second radial distance 785 is between 50% and 95% of the first radial distance 719, and the second slot 725 is located at a third radial distance 790 from the rotation center. In some embodiments, the third radial distance 790 is between 50% and 95% of the first radial distance 719, and the second radial distance 785 is greater than the third radial distance 790. In some embodiments, the rotor 717 includes at least four rotor poles.

[0097] Figure 8 A permanent magnet assisted synchronous reluctance motor 800 according to some embodiments is shown. The motor 800 includes a stator 805 and a plurality of stator winding slots 810. The stator 805 includes a plurality of stator teeth 806. The plurality of stator teeth includes a stator tooth width 807 and a stator tooth length 808. The plurality of stator winding slots 810 are configured to receive a plurality of windings 815. The motor 800 includes a rotor 817. The rotor 817 includes a circumferential outer surface 818 spaced apart from the rotation center of the rotor 817 by a first radial distance 819.

[0098] The rotor 817 includes a first slot 820 and a second slot 825. The first slot 820 includes a first arm 821 and a second arm 822, and a first magnet housing portion 823 is positioned between the first arm 821 and the second arm 822. The second slot 825 includes a first arm 826 and a second arm 827, and a second magnet housing portion 828 is positioned between the first arm 826 and the second arm 827. The first arm 821 and the second arm 822 of the first slot 820 have a first length 845 and a first width 850. In some embodiments, the first length 845 is between twice the air gap thickness and 50% of the first radial distance 819, and the first width 850 is between 2.5% and 200% of the width 835 of the first magnet housing portion. The air gap thickness is the distance between the rotor outer diameter 851 and the stator inner diameter 852. For example, in some embodiments, the first width 850 is twice the air gap thickness. The first arm 826 and the second arm 827 of the second slot 825 have a first length 855 and a first width 860. In some embodiments, the first length 855 is between twice the air gap thickness and 50% of the first radial distance 819, and the first width 860 is between 2.5% and 200% of the width 835 of the first magnet housing portion.

[0099] The first magnet housing portion 823 has a first magnet housing portion length 830 and a first magnet housing portion width 835. In some embodiments, the first magnet housing portion length 830 is greater than the stator tooth width 807, and the first magnet housing portion width 835 is between 0.5 and 10 times the air gap thickness. The second magnet housing portion 828 has a second magnet housing portion length 832 and a second magnet housing portion width 837. In some embodiments, the second magnet housing portion length 832 is greater than the stator tooth width 807, and the second magnet housing portion width 837 is between 0.5 and 10 times the air gap thickness. In some embodiments, the first magnet housing portion length 830 is greater than the second magnet housing portion length 832.

[0100] In some embodiments, the first slot 820 is referred to as the outer slot, and the second slot 825 is referred to as the inner slot. In some embodiments, the first slot 820 and the second slot 825 are positioned at different radial distances from the rotation center of the rotor 817. The first magnet housing portion 823 is positioned at a second radial distance 840 from the rotation center of the rotor 817, the second radial distance 840 being less than the first radial distance 819. In some embodiments, the first magnet housing portion 823 has a corresponding magnet fill degree or magnet fill percentage. The second magnet housing portion 828 is positioned at a third radial distance 842 from the rotation center of the rotor 817, and the third radial distance 842 is less than the first radial distance 819 and the second radial distance 840. In some embodiments, the second magnet housing portion 828 has a corresponding magnet fill degree or magnet fill percentage.

[0101] A first magnet housing portion 823 is configured to receive a magnet, such as magnet 865. A second magnet housing portion 828 is configured to receive a magnet, such as magnet 870. In some embodiments, magnet 865 is made of a rare-earth metal material, such as neodymium, while magnet 870 is made of a ferrite material. In some embodiments, magnet 865 fills between 30% and 100% of the first magnet housing portion 823. In some embodiments, magnet 865 fills between 30% and 80% of the first magnet housing portion 823. In some embodiments, magnet 870 fills between 30% and 100% of the second magnet housing portion 828. In some embodiments, magnet 870 fills between 30% and 80% of the second magnet housing portion 828. In some embodiments, magnets 865 and 870 are rare-earth magnets (e.g., neodymium magnets).

[0102] Figure 9AThis is a graphical representation of efficiency, current, and speed in revolutions per minute (“RPM”) compared to the torque output of several different motors in power tool 100, according to some embodiments. In some embodiments, the motor represented in graph 900 is a core drill motor. Graph 900 includes a representation of the efficiency of several different motors within power tool 100. Curve 902 shows the efficiency of one type of motor in power tool 100 (such as motor 500). Curve 904 shows the efficiency of a second type of motor in power tool 100 (such as motor 600). Curve 906 shows the efficiency of a third type of motor in power tool 100 (such as motor 700). Curve 908 shows the efficiency of a fourth type of motor in power tool 100 (such as motor 800). In some embodiments, curve 902 is the efficiency of motor 500 as the torque value increases. In some embodiments, curve 904 is the efficiency of motor 600 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 600 decreases at a faster rate than that of motor 500. In some embodiments, curve 906 represents the efficiency of motor 700 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 700 decreases at a faster rate than that of motors 500 and 600. In some embodiments, curve 908 represents the efficiency of motor 800 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 800 decreases at a faster rate than that of motors 500, 600, and 700.

[0103] Graph 900 additionally includes a representation of the current of several different motors within the power tool 100. Curve 910 shows the current of one type of motor in the power tool 100 (such as motor 500). Curve 912 shows the current of a second type of motor in the power tool 100 (such as motor 600). Curve 914 shows the current of a third type of motor in the power tool 100 (such as motor 700). Curve 916 shows the current of a fourth type of motor in the power tool 100 (such as motor 800). In some embodiments, curve 910 represents the current level of motor 500 as the torque value increases. In some embodiments, curve 912 represents the current of motor 600 as the torque value increases. In some embodiments, the current of both motors 500 and 600 is approximately equal for a given torque value as the torque increases. In some embodiments, curve 914 represents the current of motor 700 as the torque value increases. In some embodiments, for a given torque value, the current of motor 700 is greater than the current of motors 500 and 600 as the torque increases. In some embodiments, curve 916 represents the current of motor 800 as the torque value increases. In some embodiments, for a given torque value, the current of motor 800 is greater than the current of motors 500, 600, and 700 as the torque increases.

[0104] Graph 900 additionally includes a representation of the RPM of several different motors within power tool 100. Curve 918 shows the RPM of one type of motor in power tool 100 (such as motor 500). Curve 920 shows the RPM of a second type of motor in power tool 100 (such as motor 600). Curve 922 shows the RPM of a third type of motor in power tool 100 (such as motor 700). Curve 924 shows the RPM of a fourth type of motor in power tool 100 (such as motor 800). In some embodiments, curve 918 represents the RPM level of motor 500 as the torque value increases. In some embodiments, curve 920 represents the RPM of motor 600 as the torque value increases. In some embodiments, for a given torque value, the RPM of motor 600 starts at a higher level as the torque increases and then decreases at a faster rate than the RPM of motor 500. In some embodiments, curve 922 represents the RPM of motor 700 as the torque value increases. In some embodiments, as torque increases, for a given torque value, the RPM of motor 700 starts at a higher level and then decreases at a faster rate than the RPMs of motors 500 and 600. In some embodiments, curve 924 represents the RPM of motor 800 as the torque value increases. In some embodiments, as torque increases, for a given torque value, the RPM of motor 800 starts at a higher level and then decreases at a faster rate than the RPMs of motors 500, 600, and 700. In some embodiments, for the workload of power tool 100, each motor operates at approximately the same speed.

[0105] In some embodiments, each of motors 500, 600, 700, and 800 has a stator diameter of 80 mm and operates via a battery pack with a maximum voltage of approximately 83.5 V. In some embodiments, the stator slot fill factor for each stator winding is approximately 42%, and the phase winding resistance is between 0.11 ohms and 0.15 ohms. Table 1 below provides relative performance data for the various motors. As shown below, only a small reduction in operating time and efficiency is observed compared to the significant reduction in the amount of rare-earth magnets (e.g., neodymium) used in the motors. For example, motor 600 operates at the same speed, with the same efficiency, and with a 10% reduction in rare-earth magnet mass for the same amount of time (e.g., until the battery pack is fully discharged). Motor 700 operates at the same speed, with a 3% reduction in efficiency, and with a 38% reduction in rare-earth magnet mass for 2% less time (e.g., until the battery pack is fully discharged). Motor 800 operated at the same speed, with 7% lower efficiency and 61% less rare-earth magnet mass, for 7% less time (e.g., until the battery pack was fully discharged).

[0106]

[0107] Figure 9B This is a graphical representation of efficiency, current, and speed in revolutions per minute (“RPM”) compared to the torque output of several different motors in power tool 100, according to some embodiments. In some embodiments, the motor represented in graph 950 is a high-torque impact wrench motor. Graph 950 includes a diagram of the efficiency of several different motors within power tool 100. Curve 952 shows the efficiency of one type of motor in power tool 100 (such as motor 500). Curve 954 shows the efficiency of a second type of motor in power tool 100 (such as motor 600). Curve 956 shows the efficiency of a third type of motor in power tool 100 (such as motor 700). Curve 958 shows the efficiency of a fourth type of motor in power tool 100 (such as motor 800). In some embodiments, curve 952 is the efficiency of motor 500 as the torque value increases. In some embodiments, curve 954 is the efficiency of motor 600 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 600 decreases at a faster rate than that of motor 500. In some embodiments, curve 956 represents the efficiency of motor 700 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 700 decreases at a faster rate than that of motors 500 and 600. In some embodiments, curve 958 represents the efficiency of motor 800 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 800 decreases at a faster rate than that of motors 500, 600, and 700.

[0108] Graph 950 additionally includes a diagram illustrating the current of several different motors within the power tool 100. Curve 960 shows the current of one type of motor in the power tool (such as motor 500). Curve 962 shows the current of a second type of motor in the power tool 100 (such as motor 600). Curve 964 shows the current of a third type of motor in the power tool 100 (such as motor 700). Curve 966 shows the current of a fourth type of motor in the power tool 100 (such as motor 800). In some embodiments, curve 960 represents the current level of motor 500 as the torque value increases. In some embodiments, curve 962 represents the current of motor 600 as the torque value increases. In some embodiments, for a given torque value, the current of motor 500 is greater than the current of motor 600. In some embodiments, curve 964 represents the current of motor 700 as the torque value increases. In some embodiments, for a given torque value, the current of motor 700 is greater than the current of motors 500 and 600. In some implementations, curve 966 represents the current of motor 800 as the torque value increases. In some implementations, for a given torque value, the current of motor 800 is greater than the current of motors 500, 600, and 700 as the torque increases.

[0109] Graph 950 additionally includes a diagram of the RPM of several different motors within the power tool 100. Curve 968 shows the RPM of one type of motor in the power tool 100 (such as motor 500). Curve 970 shows the RPM of a second type of motor in the power tool 100 (such as motor 600). Curve 972 shows the RPM of a third type of motor in the power tool 100 (such as motor 700). Curve 974 shows the RPM of a fourth type of motor in the power tool 100 (such as motor 800). In some embodiments, curve 968 represents the RPM level of motor 500 as the torque value increases. In some embodiments, curve 970 represents the RPM of motor 600 as the torque value increases. In some embodiments, for a given torque value, the RPM of motor 600 starts higher and then decreases at a faster rate than the RPM of motor 500. In some embodiments, curve 972 represents the RPM of motor 700 as the torque value increases. In some embodiments, for a given torque value, the RPM of motor 700 starts high and then decreases at a faster rate than the RPMs of motors 500 and 600. In some embodiments, curve 974 represents the RPM of motor 800 as the torque value increases. In some embodiments, for a given torque value, the RPM of motor 800 starts high and then decreases faster than the RPMs of motors 500, 600, and 700. In some embodiments, for the workload of power tool 100, each motor operates at approximately the same speed.

[0110] In some embodiments, each of motors 500, 600, 700, and 800 has a stator diameter of 70 mm and operates via a battery pack with a maximum voltage of approximately 20.4 V. In some embodiments, the stator slot fill degree of each stator winding is approximately 40%, and the phase winding resistance is between 0.11 ohms and 0.15 ohms. Table 2 below provides relative performance data for the various motors. As shown below, only a small reduction in operating time and efficiency is observed compared to the significant reduction in the amount of rare-earth magnets (e.g., neodymium) used in the motors. For example, motor 600 operates at the same speed, with 1% lower efficiency and 10% less rare-earth magnet mass for the same amount of time (e.g., until the battery pack is fully discharged). Motor 700 operates at the same speed, with 4% lower efficiency and 36% less rare-earth magnet mass for 10% less time (e.g., until the battery pack is fully discharged). The motor 800 operated at the same speed, with 4% lower efficiency and 62% less rare-earth magnet mass, for 14% less time (e.g., until the battery pack was fully discharged).

[0111]

[0112] Figure 10 A surface-mounted permanent magnet motor 1000 according to some embodiments is shown. The motor 1000 includes a stator 1005 and a plurality of stator winding slots 1010. The plurality of stator winding slots 1010 are configured to receive a plurality of windings 1015. The motor 1000 includes a rotor 1017. The rotor 1017 includes a circumferential outer surface 1018 spaced apart from the rotation center of the rotor 1017 by a first radial distance 1019 (including magnets). The rotor 1017 includes a plurality of magnets 1020 disposed on the circumferential outer surface 1018 of the rotor. The plurality of magnets 1020 include slots 1025 spaced apart therebetween.

[0113] A plurality of magnets include an outer surface 1030 spaced apart from the rotation center of rotor 1017 by a first radial distance 1019. Each outer surface 1030 of each of the plurality of magnets is spaced apart by a first distance 1040. A plurality of slots extend outward from the circumferential outer surface 1018 of rotor 1017 by a second distance 1050 at a first angle 1045.

[0114] Figure 11A permanent magnet assisted synchronous reluctance motor 1100 according to some embodiments is shown. The motor 1100 includes a stator 1105 and a plurality of stator winding slots 1110. The stator 1105 includes a plurality of stator teeth 1106. The plurality of stator teeth includes a stator tooth width 1107 and a stator tooth length 1108. The plurality of stator winding slots 1110 are configured to receive a plurality of windings 1115. The motor 1100 includes a rotor 1117. The rotor 1117 includes a circumferential outer surface 1118 spaced apart from the rotation center of the rotor 1117 by a first radial distance 1119.

[0115] The rotor 1117 includes a first slot 1120 and a second slot 1125. The first slot 1120 includes a first arm 1121 and a second arm 1122, and a first magnet housing portion 1123 is positioned between the first arm 1121 and the second arm 1122. The second slot 1125 includes a first arm 1126 and a second arm 1127, and a second magnet housing portion 1128 is positioned between the first arm 1126 and the second arm 1127. The first arm 1121 and the second arm 1122 of the first slot 1120 have a first length 1155 and a first width 1157. In some embodiments, the first length 1155 is between twice the air gap thickness and 50% of the first radial distance 1119, and the first width 1157 is between 2.5% and 200% of the length 1130 of the first magnet housing portion. The air gap thickness is the distance between the rotor outer diameter 1161 and the stator inner diameter 1162. The first arm 1126 and the second arm 1127 of the second slot 1125 have a first length 1150 and a first width 1152. In some embodiments, the first length 1150 is between twice the air gap thickness and 50% of the first radial distance 1119, and the first width 1152 is between 2.5% and 200% of the length 1135 of the second magnet housing portion.

[0116] The first magnet housing portion 1123 has a first magnet housing portion length 1130 and a first magnet housing portion width 1132. In some embodiments, the first magnet housing portion length 1130 is greater than the stator tooth width 1107, and the first magnet housing portion width 1132 is between 0.5 and 10 times the air gap thickness. In some embodiments, the first magnet housing portion 1123 has a corresponding magnet filling degree or magnet filling percentage. The second magnet housing portion 1128 has a second magnet housing portion length 1135 and a second magnet housing portion width 1137. In some embodiments, the second magnet housing portion length 1135 is greater than the stator tooth width 1107, and the second magnet housing portion width 1137 is between 0.5 and 10 times the air gap thickness. In some embodiments, the second magnet housing portion 1128 has a corresponding magnet filling degree or magnet filling percentage.

[0117] In some embodiments, the first slot 1120 is referred to as the outer slot, and the second slot 1125 is referred to as the inner slot. In some embodiments, the first slot 1120 and the second slot 1125 are positioned at different radial distances from the rotation center of the rotor 1117. The first magnet housing portion 1123 is positioned at a second radial distance 1140 from the rotation center of the rotor, the second radial distance 1140 being less than the first radial distance 1119. In some embodiments, the first radial distance 1119 is not greater than 90% of the radius of the stator outer diameter, and the second radial distance 1140 is between 50% and 90% of the first radial distance 1119. The second magnet housing portion 1128 is positioned at a third radial distance 1142 from the rotation center of the rotor, the third radial distance 1142 being less than the first radial distance 1119 and the second radial distance 1140.

[0118] A first magnet housing portion 1123 is configured to receive a magnet, such as magnet 1165. Magnet 1165 has a length of 1167. In some embodiments, magnet 1165 fills between 80% and 100% of the first magnet housing portion 1123 (e.g., 90% of the length of the first magnet housing portion 1130). In some embodiments, magnet 1165 has a length of 1167 that is less than the total length of the length of the first magnet housing portion 1130. A second magnet housing portion 1128 is configured to receive a magnet, such as magnet 1170. Magnet 1170 has a length of 1172. In some embodiments, magnet 1170 fills between 80% and 100% of the second magnet housing portion 1128 (e.g., 90% of the length of the second magnet housing portion 1135). In some embodiments, magnet 1170 has a length of 1172 that is less than the total length of the length of the second magnet housing portion 1135. In some embodiments, magnets 1165 and 1170 are rare-earth magnets (e.g., neodymium magnets). In some embodiments, rotor 1117 includes at least six rotor poles.

[0119] Figure 12 A permanent magnet assisted synchronous reluctance motor 1200 according to some embodiments is shown. The motor 1200 includes a stator 1205 and a plurality of stator winding slots 1210. The stator 1205 includes a plurality of stator teeth 1206. The plurality of stator teeth includes a stator tooth width 1207 and a stator tooth length 1208. The plurality of stator winding slots 1210 are configured to receive a plurality of windings 1215. The motor 1200 includes a rotor 1217. The rotor 1217 includes a circumferential outer surface 1218 spaced apart from the rotation center of the rotor 1217 by a first radial distance 1219.

[0120] The rotor 1217 includes a first slot 1220 and a second slot 1225. The first slot 1220 includes a first arm 1221 and a second arm 1222, and a first magnet housing portion 1223 is positioned between the first arm 1221 and the second arm 1222. The second slot 1225 includes a first arm 1226 and a second arm 1227, and a second magnet housing portion 1228 is positioned between the first arm 1226 and the second arm 1227. The first arm 1221 and the second arm 1222 of the first slot 1220 have a first length 1255 and a first width 1257. In some embodiments, the first length 1255 is between twice the air gap thickness and 50% of the first radial distance 1219, and the first width 1257 is between 2.5% and 200% of the length 1230 of the first magnet housing portion. The air gap thickness is the distance between the rotor outer diameter 1261 and the stator inner diameter 1262. The first arm 1226 and the second arm 1227 of the second slot 1225 have a first length 1250 and a first width 1252. In some embodiments, the first length 1250 is between twice the air gap thickness and 50% of the first radial distance 1219, and the first width 1152 is between 2.5% and 200% of the length 1235 of the second magnet housing portion.

[0121] The first magnet housing portion 1223 has a first magnet housing portion length 1230 and a first magnet housing portion width 1232. In some embodiments, the first magnet housing portion length 1230 is greater than the stator tooth width 1207, and the first magnet housing portion width 1232 is between 0.5 and 10 times the air gap thickness. In some embodiments, the first magnet housing portion 1223 has a corresponding magnet filling degree or magnet filling percentage.

[0122] The second magnet housing portion 1228 has a second magnet housing portion length 1235 and a second magnet housing portion width 1237. In some embodiments, the second magnet housing portion length 1235 is greater than the stator tooth width 1207, and the second magnet housing portion width 1237 is between 0.5 and 10 times the air gap thickness. In some embodiments, the second magnet housing portion 1228 has a corresponding magnet filling degree or magnet filling percentage.

[0123] In some embodiments, the first slot 1220 is referred to as the outer slot, and the second slot 1225 is referred to as the inner slot. In some embodiments, the first slot 1220 and the second slot 1225 are positioned at different radial distances from the rotation center of the rotor 1217. The first magnet housing portion 1223 is positioned at a second radial distance 1240 from the rotation center of the rotor 1217, the second radial distance 1240 being less than the first radial distance 1219. In some embodiments, the first radial distance 1219 is not greater than 90% of the radius of the stator outer diameter, and the second radial distance 1240 is between 50% and 95% of the first radial distance 1219. The second magnet housing portion 1228 is positioned at a third radial distance 1242 from the rotation center of the rotor 1217, the third radial distance 1242 being less than the first radial distance 1219 and the second radial distance 1240.

[0124] The first magnet housing portion 1223 is configured to receive a magnet, such as magnet 1265. Magnet 1265 has a length 1267. In some embodiments, the magnet, such as magnet 1265, fills between 30% and 90% of the first magnet housing portion 1223 (e.g., 30% to 90% of the length 1230 of the first magnet housing portion). In some embodiments, magnet 1265 has a length 1267 that is less than the total length of the length 1230 of the first magnet housing portion.

[0125] The second magnet housing portion 1228 is configured to receive a magnet, such as magnet 1270. Magnet 1270 has a length 1272. In some embodiments, the magnet, such as magnet 1270, fills between 30% and 90% of the second magnet housing portion 1228 (e.g., 30% to 90% of the length 1235 of the second magnet housing portion). In some embodiments, magnet 1270 has a length 1272 that is less than the total length of the length 1235 of the second magnet housing portion. In some embodiments, magnets 1265 and 1270 are rare-earth magnets (e.g., neodymium magnets). In some embodiments, rotor 1217 includes at least six rotor poles.

[0126] Figure 13 A permanent magnet assisted synchronous reluctance motor 1300 according to some embodiments is shown. The motor 1300 includes a stator 1305 and a plurality of stator winding slots 1310. The stator 1305 includes a plurality of stator teeth 1306. The plurality of stator teeth includes a stator tooth width 1307 and a stator tooth length 1308. The plurality of stator winding slots 1310 are configured to receive a plurality of windings 1315. The motor 1300 includes a rotor 1317. The rotor 1317 includes a circumferential outer surface 1318 spaced apart from the rotation center of the rotor 1317 by a first radial distance 1319.

[0127] The rotor 1317 includes a first slot 1320 and a second slot 1325. The first slot 1320 includes a first arm 1321 and a second arm 1322, and a first magnet housing portion 1323 is positioned between the first arm 1321 and the second arm 1322. The second slot 1325 includes a first arm 1326 and a second arm 1327, and a second magnet housing portion 1328 is located between the first arm 1326 and the second arm 1327. The first arm 1321 and the second arm 1322 of the first slot 1320 have a first length 1355 and a first width 1357. In some embodiments, the first length 1355 is between twice the air gap thickness and 50% of the first radial distance 1319, and the first width 1357 is between 2.5% and 200% of the length 1330 of the first magnet housing portion. The air gap thickness is the distance between the rotor outer diameter 1361 and the stator inner diameter 1362. The first arm 1326 and the second arm 1327 of the second slot 1325 have a first length 1350 and a first width 1352. In some embodiments, the first length 1350 is between twice the air gap thickness and 50% of the first radial distance 1319, and the first width 1352 is between 2.5% and 200% of the length 1335 of the second magnet housing portion.

[0128] The first magnet housing portion 1323 has a first magnet housing portion length 1130 and a first magnet housing portion width 1332. In some embodiments, the first magnet housing portion length 1330 is greater than the stator tooth width 1307, and the first magnet housing portion width 1332 is between 0.5 and 10 times the air gap thickness. In some embodiments, the first magnet housing portion 1323 has a corresponding magnet filling degree or magnet filling percentage.

[0129] The second magnet housing portion 1328 has a second magnet housing portion length 1335 and a second magnet housing portion width 1337. In some embodiments, the second magnet housing portion length 1335 is greater than the stator tooth width 1307, and the second magnet housing portion width 1337 is 0.5 to 10 times the air gap thickness. In some embodiments, the second magnet housing portion 1328 has a corresponding magnet filling degree or magnet filling percentage.

[0130] The first magnet housing portion 1323 is positioned at a second radial distance 1340 from the rotation center of the rotor 1317, the second radial distance 1340 being less than the first radial distance 1319. The second magnet housing portion 1328 is positioned at a third radial distance 1342 from the rotation center of the rotor 1317, the third radial distance 1342 being less than the first radial distance 1319 and the second radial distance 1340. In some embodiments, the first radial distance 1319 is not greater than 90% of the radius of the stator outer diameter, the second radial distance 1340 is between 50% and 95% of the first radial distance 1319, and the third radial distance 1342 is between 50% and 95% of the first radial distance 1319.

[0131] The first magnet housing portion 1323 is configured to receive a magnet, such as magnet 1365. Magnet 1365 has a length of 1367. In some embodiments, the magnet, such as magnet 1365, fills between 30% and 100% of the first magnet housing portion 1323 (e.g., between 30% and 100% of the length 1330 of the first magnet housing portion). In some embodiments, magnet 1365 has a length 1367 that is less than the total length of the length 1330 of the first magnet housing portion. In some embodiments, magnet 1365 is made of a rare earth metal material such as neodymium.

[0132] In some embodiments, the first slot 1320 is referred to as the outer slot, and the second slot 1325 is referred to as the inner slot. In some embodiments, the first slot 1320 and the second slot 1325 are positioned at different radial distances from the rotation center of the rotor 1317. The second magnet housing portion 1328 is configured to receive a magnet, such as magnet 1370. Magnet 1370 has a length 1372. In some embodiments, magnet 1370 fills between 30% and 100% of the second magnet housing portion 1328 (e.g., between 30% and 100% of the length 1335 of the second magnet housing portion). In some embodiments, magnet 1370 has a length 1372 that is less than the total length of the second magnet housing portion length 1335. In some embodiments, magnet 1370 is made of a different material than magnet 1365, such as ferrite. In some embodiments, the rotor 1317 includes at least six rotor poles.

[0133] Figure 14This is a graphical representation of efficiency, current, and speed in revolutions per minute ("RPM") compared to the torque output of several different motors in power tool 100, according to some embodiments. In some embodiments, the motor represented in graph 1400 is a motor of a flatbed compactor. Graph 1400 includes a representation of the efficiency of several different motors within power tool 100. Curve 1402 shows the efficiency of one type of motor in power tool 100 (such as motor 1000). Curve 1404 shows the efficiency of a second type of motor in power tool 100 (such as motor 1100). Curve 1406 shows the efficiency of a third type of motor in power tool 100 (such as motor 1200). Curve 1408 shows the efficiency of a fourth type of motor in power tool 100 (such as motor 1300). In some embodiments, curve 1402 is the efficiency of motor 1000 as the torque value increases. In some embodiments, curve 1404 is the efficiency of motor 1100 as the torque value increases. In some embodiments, the efficiency of motor 1100 is approximately equal to that of motor 1000, which has an efficiency of less than 5.0 Nm. In some embodiments, curve 1406 represents the efficiency of motor 1200 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 1200 decreases at a faster rate than that of motors 1100 and 1000. In some embodiments, curve 1408 represents the efficiency of motor 1300 as the torque value increases. In some embodiments, the efficiency of motor 1300 decreases at a faster rate than that of motors 1000 and 1100.

[0134] Graph 1400 further includes a representation of the current of several different motors within the power tool 100. Curve 1410 shows the current of one type of motor in the power tool 100 (such as motor 1000). Curve 1412 shows the current of a second type of motor in the power tool 100 (such as motor 1100). Curve 1414 shows the current of a third type of motor in the power tool 100 (such as motor 1200). Curve 1416 shows the current of a fourth type of motor in the power tool 100 (such as motor 1300). In some embodiments, curve 1410 represents the current level of motor 1000 as the torque value increases. In some embodiments, curve 1412 represents the current of motor 1100 as the torque value increases. In some embodiments, the currents of motors 1000 and 1100 are approximately equal below 3.0 Nm as the torque increases. In some embodiments, curve 1414 represents the current of motor 1200 as the torque value increases. In some embodiments, as torque increases, for a given torque value, the current of motor 1200 is greater than that of both motors 1000 and 1100. In some embodiments, curve 1416 represents the current of motor 1300 as the torque value increases. In some embodiments, as torque increases, for a given torque value, the current of motor 1300 is greater than that of motors 1000, 1100, and 1200.

[0135] Graph 1400 additionally includes a representation of the RPM of several different motors within power tool 100. Curve 1418 shows the RPM of one type of motor in power tool 100 (such as motor 1000). Curve 1420 shows the RPM of a second type of motor in power tool 100 (such as motor 1100). Curve 1422 shows the RPM of a third type of motor in power tool 100 (such as motor 1200). Curve 1424 shows the RPM of a fourth type of motor in power tool 100 (such as motor 1300). In some embodiments, curve 1418 represents the RPM level of motor 1000 as torque increases. In some embodiments, curve 1420 represents the RPM of motor 1100 as torque increases. In some embodiments, as torque increases, the RPM of motor 1100 is approximately equal to the RPM of motor 1000, which is less than approximately 5 Nm. In some embodiments, as torque increases, the RPM of motor 1100 decreases at a faster rate than that of motor 1000 after approximately 5 Nm. In some embodiments, curve 1422 represents the RPM of motor 1200 as torque increases. In some embodiments, as torque increases, the RPM of motor 1200 is approximately equal to that of motors 1000 and 1100 until approximately 3.5 Nm. In some embodiments, as torque increases, the RPM of motor 1200 decreases at a faster rate than that of motors 1000 and 1100 after approximately 3.5 Nm. In some embodiments, curve 1424 represents the RPM of motor 1300 as torque increases. In some embodiments, as torque increases, the RPM of motor 1300 is equal to the RPM of motors 1000 and 1100, which are below 4 Nm. In some embodiments, as torque increases, the RPM of motor 1300 decreases faster after 4 Nm than that of motors 1000 and 1100. In some embodiments, each motor operates at approximately the same speed for the workload of power tool 100.

[0136] In some embodiments, each of motors 1000, 1100, 1200, and 1300 has a stator diameter of 100 mm and is operated by a battery pack with a maximum voltage of approximately 83.5 V. In some embodiments, the stator slot fill factor for each stator winding is approximately 43%, and the phase winding resistance is between 0.11 ohms and 0.25 ohms. Table 3 below provides relative performance data for the various motors. As shown below, only a small reduction in operating time and efficiency is observed compared to a significant reduction in the amount of rare-earth magnets (e.g., neodymium) used in the motors. For example, motor 1100 operates for the same amount of time (e.g., until the battery pack is fully discharged) with the same efficiency, while the rare-earth magnet mass is reduced by 6%. Motor 1200 operates for 3% less time (e.g., until the battery pack is fully discharged), with a 1% reduction in efficiency and a 35% reduction in rare-earth magnet mass. Motor 1300 operates for 3% less time (e.g., until the battery pack is fully discharged), with a 2% reduction in efficiency and a 46% reduction in rare-earth magnet mass.

[0137]

[0138] Figure 15 An internal permanent magnet motor 1500 according to some embodiments is shown. The motor 1500 includes a stator 1505 and a plurality of stator winding slots 1510. The plurality of stator winding slots 1510 are configured to receive a plurality of windings 1515. The motor 1500 includes a rotor 1517. The rotor 1517 includes a circumferential outer surface 1518 spaced apart from a rotation center of the rotor 1517 by a first radial distance 1519. The rotor 1517 includes a plurality of slots 1520 configured to receive magnets. In some embodiments, a slot 1520 includes a first arm 1521 and a second arm 1522, and a magnet housing portion 1523 of the slot located therebetween. The magnet housing portion 1523 is configured to spaced apart from the rotation center of the rotor 1517 by a second radial distance 1540. The magnet housing portion 1523 is configured to receive a magnet 1525 having a length 1526 and a width 1527. In some embodiments, the magnet 1525 has a length 1526 that fills approximately 100% of the magnet housing portion 1523.

[0139] Figure 16A permanent magnet assisted synchronous reluctance motor 1600 according to some embodiments is shown. The motor 1600 includes a stator 1605 and a plurality of stator winding slots 1610. In some embodiments, the stator 1605 is configured to include at least twelve stator slots. The stator 1605 includes a plurality of stator teeth 1606. The plurality of stator teeth includes a stator tooth width 1607 and a stator tooth length 1608. The plurality of stator winding slots 1610 are configured to receive a plurality of windings 1615. The motor 1600 includes a rotor 1617. The rotor 1617 includes a circumferential outer surface 1618 spaced from the rotation center of the rotor 1617 by a first radial distance 1619. In some embodiments, the first radial distance 1619 is not greater than 90% of the radius of the stator outer diameter.

[0140] The rotor 1617 includes a first slot 1620 and a second slot 1625. The first slot 1620 includes a first arm 1621 and a second arm 1622, and a first magnet housing portion 1623 is located between the first arm 1621 and the second arm 1622. The second slot 1625 includes a first arm 1626 and a second arm 1627, and a second magnet housing portion 1628 is located between the first arm 1626 and the second arm 1627.

[0141] The first arm 1621 and the second arm 1622 of the first slot 1620 have a first length 1645 and a first width 1650. In some embodiments, the first length 1645 is between twice the air gap thickness and 50% of the first radial distance 1619, and the first width 1650 is between 2.5% and 200% of the length 1675 of the first magnet housing portion. The air gap thickness is the distance between the rotor outer diameter 1661 and the stator inner diameter 1362. The first magnet housing portion 1623 has a first magnet housing portion length 1675 and a first magnet housing portion width 1676. In some embodiments, the first magnet housing portion length 1675 is greater than the stator tooth width 1607, and the first magnet housing portion width 1676 is between 0.5 and 10 times the air gap thickness. In some embodiments, the first magnet housing portion 1623 has a corresponding magnet filling degree or magnet filling percentage.

[0142] The first arm 1626 and the second arm 1627 of the second slot 1625 have a first length 1630 and a first width 1635. In some embodiments, the first length 1630 is between twice the air gap thickness and 50% of the first radial distance 1619, and the first width 1635 is between 0.5 and 10 times the air gap thickness. The second magnet housing portion 1628 has a second magnet housing portion length 1680 and a second magnet housing portion width 1681. In some embodiments, the second magnet housing portion length 1680 is greater than the stator tooth width 1607, and the second magnet housing portion width 1681 is between 2.5% and 200% of the length 1665 of the magnet 1660. In some embodiments, the second magnet housing portion 1628 has a corresponding magnet filling degree or magnet filling percentage.

[0143] The first magnet housing portion 1623 is configured to receive a magnet, such as magnet 1655. In some embodiments, the magnet, such as magnet 1655, fills 30% to 100% of the first magnet housing portion 1623 (e.g., 30% to 100% of the length 1675 of the first magnet housing portion). In some embodiments, magnet 1655 has a length 1670 that is less than the total length of the length 1675 of the first magnet housing portion.

[0144] The second magnet housing portion 1628 is configured to receive a magnet, such as magnet 1660. In some embodiments, similar to the first magnet housing portion, the second magnet housing portion 1628 is configured to receive a magnet filling 30% to 100% of the second magnet housing portion 1628 (e.g., 30% to 100% of the length 1680 of the second magnet housing portion). In some embodiments, magnet 1660 has a length 1665 that is less than the length 1675 of the first magnet housing portion. In some embodiments, the degree to which magnet 1660 fills the second magnet housing portion 1628 is at least as high as the degree to which magnet 1655 fills the first magnet housing portion 1623. For example, the percentage of filling of magnet 1655 to the first magnet housing portion 1623 is greater than the percentage of filling of magnet 1660 to the second magnet housing portion 1628. In some embodiments, magnet 1660 fills between 30% and 100% of the second magnet housing portion 1628. In some implementations, magnets 1655 and 1660 are rare-earth magnets (e.g., neodymium magnets).

[0145] In some embodiments, the first slot 1620 is referred to as the outer slot, and the second slot 1625 is referred to as the inner slot. In some embodiments, the first slot 1620 and the second slot 1625 are located at different radial distances from the rotation center of the rotor 1617. For example, the first slot 1620 is located at a second radial distance 1685 from the rotation center of the rotor 1617. In some embodiments, the second radial distance 1685 is between 50% and 95% of the first radial distance 1619, and the second slot 1625 is located at a third radial distance 1690 from the rotation center of the rotor 1617. In some embodiments, the third radial distance 1690 is between 50% and 95% of the first radial distance 1619. In some embodiments, the first radial distance 1619 is greater than the second radial distance 1685. In some embodiments, the rotor 1617 includes at least four rotor poles.

[0146] Figure 17 A permanent magnet assisted synchronous reluctance motor 1700, comprising magnets made of two different materials, is shown according to some embodiments. The motor 1700 includes a stator 1705 and a plurality of stator winding slots 1710. The stator 1705 includes a plurality of stator teeth 1706. The plurality of stator teeth includes a stator tooth width 1707 and a stator tooth length 1708. In some embodiments, the stator 1705 is configured to include at least twelve stator slots. The plurality of stator winding slots 1710 are configured to receive a plurality of windings 1715. The motor 1700 includes a rotor 1717. The rotor 1717 includes a circumferential outer surface 1718 spaced from the rotation center of the rotor 1717 by a first radial distance 1719. In some embodiments, the first radial distance 1719 is not greater than 90% of the radius of the stator outer diameter.

[0147] The rotor 1717 includes a first slot 1720 and a second slot 1725. The first slot 1720 includes a first arm 1721 and a second arm 1722, and a first magnet housing portion 1723 is located between the first arm 1721 and the second arm 1722. The second slot 1725 includes a first arm 1726 and a second arm 1727, and a second magnet housing portion 1728 is located between the first arm 1726 and the second arm 1727.

[0148] The first arm 1721 and the second arm 1722 of the first slot 1720 have a first length 1745 and a first width 1750. In some embodiments, the first length 1745 is between twice the air gap thickness and 50% of the first radial distance 1719, and the first width 1750 is between 2.5% and 200% of the length 1775 of the first magnet housing portion. The air gap thickness is the distance between the rotor outer diameter 1761 and the stator inner diameter 1762. The first magnet housing portion 1723 has a first magnet housing portion length 1775 and a first magnet housing portion width 1776. In some embodiments, the first magnet housing portion length 1775 is greater than the stator tooth width 1707, and the first magnet housing portion width 1776 is 0.5 to 10 times the air gap thickness. In some embodiments, the first magnet housing portion 1723 has a corresponding magnet filling degree or magnet filling percentage.

[0149] The first arm 1726 and the second arm 1727 of the second slot 1725 have a first length 1730 and a first width 1735. In some embodiments, the first length 1730 is between twice the air gap thickness and 50% of the first radial distance 1719, and the first width 1735 is between 2.5% and 200% of the length 1780 of the second magnet housing portion. The second magnet housing portion 1728 has a second magnet housing portion length 1780 and a second magnet housing portion width 1781. In some embodiments, the second magnet housing portion length 1780 is greater than the stator tooth width 1707, and the second magnet housing portion width 1781 is 0.5 to 10 times the air gap thickness. In some embodiments, the second magnet housing portion 1728 has a corresponding magnet filling degree or magnet filling percentage.

[0150] The first magnet housing portion 1723 is configured to receive a magnet, such as magnet 1755. In some embodiments, the magnet, such as magnet 1755, fills between 30% and 100% of the first magnet housing portion 1723 (e.g., 30% and 100% of the length 1775 of the first magnet housing portion). In some embodiments, magnet 1755 has a length 1770 that is less than the total length of the length 1775 of the first magnet housing portion.

[0151] The second magnet housing portion 1728 is configured to receive a magnet, such as magnet 1760. In some embodiments, similar to the first magnet housing portion, the second magnet housing portion 1728 is configured to receive a magnet filling the second magnet housing portion 1728, which fills between 30% and 100% of the second magnet housing portion 1728 (e.g., 30% to 100% of the length 1780 of the second magnet housing portion). In some embodiments, magnet 1760 has a length 1765 that is less than the length 1775 of the first magnet housing portion. In some embodiments, the degree to which magnet 1760 fills the second magnet housing portion 1728 is at least as high as the degree to which magnet 1755 fills the first magnet housing portion 1723. For example, the percentage of filling of magnet 1755 corresponding to the first magnet housing portion 1773 is greater than the percentage of filling of the second magnet housing portion 1728 by magnet 1760. In some embodiments, magnet 1760 fills between 30% and 90% of the second magnet housing portion 1678. In some embodiments, magnets 1755 and 1760 are rare-earth magnets (e.g., neodymium magnets).

[0152] In some embodiments, the first slot 1720 is referred to as the outer slot, and the second slot 1725 is referred to as the inner slot. In some embodiments, the first slot 1720 and the second slot 1725 are located at different radial distances from the rotation center of the rotor 1717. For example, the first slot 1720 is located at a second radial distance 1785 from the rotation center of the rotor 1717. In some embodiments, the second radial distance 1785 is no greater than 50% to 95% of the first radial distance 1719, and the second slot 1725 is located at a third radial distance 1790 from the rotation center of the rotor 1717. In some embodiments, the third radial distance 1790 is between 50% and 95% of the first radial distance 1719. In some embodiments, the second radial distance 1785 is greater than the third radial distance 1790. In some embodiments, the rotor 1717 includes at least four rotor poles.

[0153] Figure 18This is a graphical representation of efficiency, current, and speed in revolutions per minute (“RPM”) compared to the torque output of several different internal permanent magnet motors in power tool 100, according to some embodiments. In some embodiments, the motor represented in graph 1800 is a motor of a small angle grinder. Graph 1800 includes a representation of the efficiency of several different motors within power tool 100. Curve 1802 shows the efficiency of one type of motor in power tool 100 (such as motor 1500). Curve 1804 shows the efficiency of a second type of motor in power tool 100 (such as motor 1600). Curve 1806 shows the efficiency of a third type of motor in power tool 100 (such as motor 1700). In some embodiments, curve 1802 is the efficiency of motor 1500 as the torque value increases. In some embodiments, curve 1804 is the efficiency of motor 1600 as the torque value increases. In some embodiments, as torque increases, for a given torque value, the efficiency of motor 1600 decreases at a faster rate than that of motor 1500. In some embodiments, curve 1806 represents the efficiency of motor 1700 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 1700 decreases at a faster rate than that of motors 1600 and 1500.

[0154] Graph 1800 additionally includes a representation of the current of several different motors within the power tool 100. Curve 1808 shows the current of one type of motor in the power tool 100 (such as motor 1500). Curve 1810 shows the current of a second type of motor in the power tool 100 (such as motor 1600). Curve 1812 shows the current of a third type of motor in the power tool 100 (such as motor 1700). In some embodiments, curve 1808 represents the current level of motor 1500 as the torque value increases. In some embodiments, curve 1810 represents the current of motor 1600 as the torque value increases. In some embodiments, the currents of motors 1500 and 1600 are approximately equal below 4.5 Nm as the torque increases. In some embodiments, curve 1812 represents the current of motor 1700 as the torque value increases. In some embodiments, for a given torque value, the current of motor 1700 is greater than that of both motors 1500 and 1600 as the torque increases.

[0155] Graph 1800 additionally includes a representation of the RPM of several different motors within the power tool 100. Curve 1812 shows the RPM of one type of motor in the power tool (such as motor 1500). Curve 1814 shows the RPM of a second type of motor in the power tool 100 (such as motor 1600). Curve 1816 shows the RPM of a third type of motor in the power tool 100 (such as motor 1700). In some embodiments, curve 1812 represents the RPM level of motor 1500 as the torque value increases. In some embodiments, curve 1814 represents the RPM of motor 1600 as the torque value increases. In some embodiments, as the torque increases, for a given torque value, the RPM of motor 1600 starts higher and then decreases at a faster rate than the RPM of motor 1500. In some embodiments, curve 1816 represents the RPM of motor 1700 as the torque value increases. In some implementations, as torque increases, for a given torque value, the RPM of motor 1700 starts higher and then decreases at a faster rate than that of motors 1500 and 1600.

[0156] In some embodiments, each of motors 1500, 1600, and 1700 has a stator diameter of 60 mm and is operated by a battery pack with a maximum voltage of approximately 20.4 V. In some embodiments, the stator slot fill factor for each stator winding is approximately 45%, and the phase winding resistance is between 6 milliohms and 11 milliohms. Table 4 below provides relative performance data for the various motors. As shown below, only a small reduction in operating time and efficiency is observed compared to the significant reduction in the amount of rare-earth magnets (e.g., neodymium) used in the motors. For example, motor 1600 operates at the same speed for the same amount of time (e.g., until the battery pack is fully discharged), with a 1% increase in efficiency and a 22% reduction in rare-earth magnet mass. Motor 1700 operates at the same speed for 19% less time (e.g., until the battery pack is fully discharged), with a 5% decrease in efficiency and a 70% reduction in rare-earth magnet mass.

[0157]

[0158] Figure 19A ribbed permanent magnet assisted synchronous reluctance motor 1900 is shown according to some embodiments. The motor 1900 includes a stator 1905 and a plurality of stator winding slots 1910. The stator 1905 includes a plurality of stator teeth 1906. The plurality of stator teeth includes a stator tooth width 1907 and a stator tooth length 1908. The plurality of stator winding slots 1910 are configured to receive a plurality of windings 1915. The motor 1900 includes a rotor 1917. The rotor 1917 includes a first slot 1920 and a second slot 1925. The first slot 1920 includes a first arm 1921 and a second arm 1922, and a first magnet housing portion 1923 is located between the first arm 1921 and the second arm 1922. The second slot 1925 includes a first arm 1926 and a second arm 1927, and a second magnet housing portion 1928 is positioned between the first arm 1926 and the second arm 1927. The rotor 1917 includes a circumferential outer surface 1918 of the rotor 1917, which is spaced from the rotation center of the rotor 1917 by a first radial distance 1919. In some embodiments, the first radial distance 1919 is not greater than 90% of the radius of the stator outer diameter. The first arm 1921 and the second arm 1922 of the first slot 1920 include a first width 1934 and a first length 1930. In some embodiments, the first width 1934 is between 2% and 50% of the first length 1935 of the first magnet housing portion 1923, and the first length 1930 is between twice the air gap thickness and 50% of the first radial distance 1919. The air gap thickness is the distance between the rotor outer diameter 1961 and the stator inner diameter 1962. The first arm 1926 and the second arm 1927 of the second slot 1925 include a first width 1933 and a first length 1932. In some embodiments, the first width 1933 is between 2.5% and 200% of the first length 1940 of the second magnet housing portion 1928, and the first length 1932 is between twice the air gap thickness and 50% of the first radial distance 1919.

[0159] The first magnet housing portion 1923 includes a first width 1950 and a first length 1935. In some embodiments, the first width 1950 is between 0.5 and 10 times the air gap thickness, and the first length 1935 is greater than 50% of the width of the stator tooth width 1907. The first magnet housing portion 1923 includes a first steel rib 1985, which is positioned at the center of the first magnet housing portion 1923 and is equidistant from the first arm 1921 and the second arm 1922 of the first slot 1920. In some embodiments, the first steel rib 1985 is configured to have a length 1980 and fill a portion of the first magnet housing portion 1923 equal to the length 1980 of the first steel rib 1985.

[0160] The second magnet housing portion 1928 includes a first width 1945 and a first length 1940. In some embodiments, the first width 1945 is between 0.5 and 10 times the air gap thickness, and the first length 1940 is greater than 50% of the width of the stator tooth width 1907. The second magnet housing portion 1928 includes a second steel rib 1987 located at the center of the second magnet housing portion 1928 and equidistant from the first arm 1926 and the second arm 1927 of the second slot 1925. In some embodiments, the second steel rib 1987 is configured to have a length 1980 that is the same as the length of the first steel rib 1985, and fills a portion of the second magnet housing portion 1928 equal to the length 1980 of the second steel rib 1987.

[0161] In some embodiments, the first slot 1920 is referred to as the outer slot, and the second slot 1925 is referred to as the inner slot. In some embodiments, the first slot and the second slot are located at different radial distances from the rotation center of the rotor 1917. For example, the first slot 1920 is located at a second radial distance 1955 from the rotation center, the second radial distance being no greater than 50% to 95% of the first radial distance 1919, and the second slot 1925 is located at a third radial distance 1960 from the rotation center, the third radial distance being between 50% and 95% of the first radial distance 1919, and wherein the second radial distance 1955 is greater than the third radial distance 1960.

[0162] The first magnet housing portion 1923 is configured to receive a magnet, such as magnet 1965. In some embodiments, magnet 1965 is configured to fill approximately 100% of the first magnet housing portion 1923 that is not filled by the first steel rib 1985. The second magnet housing portion 1928 is configured to receive a magnet, such as magnet 1970. In some embodiments, magnet 1970 is configured to fill approximately 100% of the second magnet housing portion 1928 that is not filled by the second steel rib 1987. In some embodiments, magnets 1965 and 1970 each comprise two magnets for filling a corresponding magnet housing portion on either side of steel ribs 1985 and 1987. Steel ribs 1985 and 1987 can be similarly implemented in any rotor disclosed in this invention.

[0163] Figure 20A ribbed permanent magnet assisted synchronous reluctance motor 2000 according to some embodiments is shown. The motor 1000 includes a stator 2005 and a plurality of stator winding slots 2010. The stator 2005 includes a plurality of stator teeth 2006. The plurality of stator teeth includes a stator tooth width 2007 and a stator tooth length 2008. The plurality of stator winding slots 1910 are configured to receive a plurality of windings 1915. The motor 2000 includes a rotor 2017. The rotor 2017 includes a first slot 2020 and a second slot 2025. The first slot 2020 includes a first arm 2021 and a second arm 2022, with a first magnet housing portion 2023 located between the first arm 2021 and the second arm 2022. The second slot 2025 includes a first arm 2026 and a second arm 2027, with a second magnet housing portion 2028 positioned between the first arm 2026 and the second arm 2027. The rotor 2017 includes a circumferential outer surface 2018, which is spaced apart from the rotation center of the rotor 2017 by a first radial distance 2019. In some embodiments, the first radial distance 2019 is not greater than 90% of the radius of the stator outer diameter.

[0164] The first arm 2021 and the second arm 2022 of the first slot 2020 include a first width 2034 and a first length 2030. In some embodiments, the first width 2034 is between 2.5% and 200% of the first length 2035, and the first length 2030 is between twice the air gap thickness and 50% of the first radial distance 2019. The air gap thickness is the distance between the rotor outer diameter 2061 and the stator inner diameter 2062. The first arm 2026 and the second arm 2027 of the second slot 2025 include a first width 2033 and a first length 2032. In some embodiments, the first width 2033 is between 2.5% and 200% of the first length 2040 of the second magnet housing portion 2028, and the first length 2032 is between twice the air gap thickness and 50% of the first radial distance 2019.

[0165] The first magnet housing portion 2023 includes a first width 2050 and a first length 2035. In some embodiments, the first width 2050 is between 0.5 and 10 times the air gap thickness, and the first length 2035 is greater than the stator tooth width 2007. The first magnet housing portion 2023 includes a first steel rib 2085 positioned between a first arm 2021 of the first slot 2020 and the first magnet housing portion 2023, and a second steel rib 2086 positioned between a second arm 2022 of the first slot 2020 and the first magnet housing portion 2023. In some embodiments, the first steel rib 2085 and the second steel rib 2086 are configured to have a length 2080 and fill a portion of the first magnet housing portion 2023 equal to the length 2080 of the first steel rib 2085 and the second steel rib 2086.

[0166] The second magnet housing portion 2028 includes a first width 2045 and a first length 2040. In some embodiments, the first width 2045 is between 0.5 and 10 times the air gap thickness, and the first length 2040 is greater than the stator tooth width 2007. The second magnet housing portion 2028 includes a third steel rib 2087 positioned between a first arm 2026 of the second slot 2025 and the second magnet housing portion 2028, and a fourth steel rib 2088 positioned between a second arm 2027 of the second slot 2025 and the second magnet housing portion 2028. In some embodiments, the third steel rib 2087 and the fourth steel rib 2088 are configured to have a length 2080 and fill a portion of the second magnet housing portion 2028 equal to the length 2080 of the third steel rib 2087 and the fourth steel rib 2088. In some embodiments, the third steel rib 2087 and the fourth steel rib 2088 are configured to have a length of 2080 and fill the portion of the second magnet housing portion 2028 that is equal to the length 2080 of the third steel rib 2087 and the fourth steel rib 2088.

[0167] In some embodiments, the first slot 2020 is referred to as the outer slot, and the second slot 2025 is referred to as the inner slot. In some embodiments, the first slot and the second slot are located at different radial distances from the rotation center of the rotor 2017. For example, the first slot 2020 is located at a second radial distance 2055 from the rotation center of the rotor 2017, the second radial distance being no greater than 50% to 95% of the first radial distance 2019, and the second slot 2025 is located at a third radial distance 2060 from the rotation center of the rotor 2017, the third radial distance being between 50% and 95% of the first radial distance 2019, and wherein the second radial distance 2055 is greater than the third radial distance 2060.

[0168] The first magnet housing portion 2023 is configured to receive a magnet, such as magnet 2065. In some embodiments, magnet 2065 is configured to fill approximately 100% of the first magnet housing portion 2023 that is not filled by the first steel rib 2085 or the second steel rib 2086. The second magnet housing portion 2028 is configured to receive a magnet, such as magnet 2070. In some embodiments, magnet 2070 is configured to fill approximately 100% of the second magnet housing portion 2028 that is not filled by the third steel rib 2087 or the fourth steel rib 2088. Steel ribs 2085, 2086, 2087, and 2088 can be similarly implemented in any rotor disclosed in this invention.

[0169] Figure 21An internal permanent magnet motor 2100 according to some embodiments is shown. The motor 2100 includes an outer diameter, for example, between 60 mm and 65 mm. In some cases, the outer diameter of the motor 2100 is approximately 63 mm. The motor 2100 includes a stator 2105 and a plurality of stator winding slots 2110. The plurality of stator winding slots 2110 are configured to receive a plurality of stator windings 2115. The plurality of windings are wound on one or more of a plurality of stator teeth 2114. The stator winding slots 2110 include an outer stator winding periphery 2111 and an inner stator winding periphery 2112. The outer stator winding periphery 2111 and the inner stator winding periphery 2112 are offset from each other by a stator winding slot radius 2113. In some embodiments, the stator winding slots 2110 include winding gaps. For example, in some embodiments, the motor 2100 may include an air gap between the plurality of stator windings 2115. In some cases, such as Figure 21 As shown, the plurality of stator windings 2115 do not include the winding gaps.

[0170] Motor 2100 includes a rotor 2117. Motor 2100 may include a pair of first slots and second slots for each pole (e.g., four-pole, six-pole, etc.) of rotor 2117. In some cases, motor 2100 is also referred to as a 4-pole 6-slot IPM motor. Rotor 2117 includes a circumferential outer surface 2118 spaced from the rotation center of rotor 2117 by a first radial distance 2119. Rotor 2117 includes a plurality of slots 2120 configured to receive magnets. In some embodiments, slot 2120 includes a first arm 2121 and a second arm 2122, and a magnet housing portion 2123 of the slot located therebetween. Magnet housing portion 2123 is configured to be spaced from the rotation center of rotor 2117 by a second radial distance 1540. Magnet housing portion 2123 is configured to receive a magnet 2125 having a length 2126 and a width 2127. In some embodiments, the magnet 2125 has a length 2126 that fills approximately 100% of the magnet housing portion 2123.

[0171] Figure 22A permanent magnet assisted synchronous reluctance motor 2200 according to some embodiments is shown. The motor 2200 includes an outer diameter, for example, between 60 mm and 65 mm. In some cases, the outer diameter of the motor 2200 is approximately 63 mm. The motor 2200 includes a stator 2205 and a plurality of stator winding slots 2210. The plurality of stator winding slots 2210 are configured to receive a plurality of windings 2215. The plurality of windings are wound on one or more of a plurality of stator teeth 2214. The stator winding slots 2210 include an outer stator winding periphery 2211 and an inner stator winding periphery 2212. The outer stator winding periphery 2211 and the inner stator winding periphery 2212 are offset from each other by a stator winding slot radius 2213. The motor 2200 also includes an air gap thickness, which is the distance between the rotor outer diameter and the stator inner diameter.

[0172] In some embodiments, the plurality of windings 2215 are configured as distributed windings (e.g., the opposite of concentrated windings). For example, the plurality of windings 2215 are wound on at least two of the plurality of stator teeth 2214. In this example, the plurality of windings 2215 are divided into a number of smaller coils configured to be evenly distributed around the periphery of the stator core. This advantageously reduces harmonic distortion in the motor 2200, which can lead to... Figure 24 This results in higher efficiency, lower noise, and other performance improvements. Additionally, the distributed multiple windings 2215 can provide a more uniform magnetic flux distribution.

[0173] Motor 2200 also includes rotor 2217. Rotor 2217 includes a first slot 2220 and a second slot 2225. First slot 2220 includes a first arm 2221 and a second arm 2222, and a first magnet housing portion 2223 located between the first arm 2221 and the second arm 2222. Second slot 2225 includes a first arm 2226 and a second arm 2227, and a second magnet housing portion 2228 located between the first arm 2226 and the second arm 2227. Motor 2200 may include a pair of first slots and second slots for each pole (e.g., four-pole, six-pole, etc.) of rotor 2217.

[0174] The rotor 2217 includes a circumferential outer surface 2218 spaced 2219 radially from the rotor's rotation center. In some embodiments, the first radial distance 2219 is no greater than 90% of the radius of the stator outer diameter. The first arm 2221 of the first slot 2220 includes a first width 2234 and a first length 2230. In some embodiments, the first width 2234 is between 2.5% and 200% of the magnet housing width 2245, and the first length 2230 is between twice the air gap thickness and 50% of the first radial distance 2219. The air gap thickness is the distance between the rotor outer diameter 2261 and the stator inner diameter 2262. The first magnet housing portion 2223 includes a first width 2250 and a first length 2235.

[0175] In some embodiments, the first width 2250 is between 0.5 and 10 times the air gap thickness, and the first length 2235 is greater than the stator tooth width. The first arm 2226 of the second slot 2225 includes a first width 2233 and a first length 2232. In some embodiments, the first width 2233 is between 2.5% and 200% of the magnet housing width 2245, and the first length 2232 is between twice the air gap thickness and 50% of the first radial distance 2219. The second magnet housing portion 2228 includes a first length 2240 and a first width 2250. In some embodiments, the first width 2250 is between 0.5 and 10 times the air gap thickness, and the first length 2240 is greater than the stator tooth width.

[0176] In some embodiments, the first slot 2220 is referred to as the outer slot, and the second slot 2225 is referred to as the inner slot. In some embodiments, the first slot 2220 and the second slot 2225 are located at different radial distances from the rotation center of the rotor 2217. For example, the first slot 2220 is located at a second radial distance 2255 from the rotation center of the rotor 2217. In some embodiments, the second radial distance 2255 is not greater than 50% to 95% of the first radial distance 2219, and the second slot 2225 is located at a third radial distance 2260 from the rotation center. In some embodiments, the third radial distance is between 50% and 95% of the first radial distance 2219, wherein the second radial distance 2255 is greater than the third radial distance 2260.

[0177] A first magnet housing portion 2223 is configured to receive a magnet, such as magnet 2265. In some embodiments, magnet 2265 is configured to fill approximately 80% to 100% of the first magnet housing portion 2223. A second magnet housing portion 2228 is configured to receive a magnet, such as magnet 2270. In some embodiments, magnet 2270 is configured to fill approximately 100% of the second magnet housing portion 2228. In some embodiments, magnets 2265 and 2270 are rare-earth magnets (e.g., neodymium magnets).

[0178] Figure 23 A permanent magnet assisted synchronous reluctance motor 2300 according to some embodiments is shown. The motor 2300 includes an outer diameter, for example, between 60 mm and 65 mm. In some cases, the outer diameter of the motor 2300 is approximately 63 mm. The motor 2300 includes a stator 2305 and a plurality of stator winding slots 2310. In some embodiments, the plurality of stator winding slots 2310 includes at least six stator slots. The plurality of stator winding slots 2310 are configured to receive a plurality of windings 2315. The plurality of windings are wound on one or more of a plurality of stator teeth 2314. The stator winding slot 2310 includes an outer stator winding periphery 2311 and an inner stator winding periphery 2312. The outer stator winding periphery 2311 and the inner stator winding periphery 2312 are offset from each other by a stator winding slot radius 2313. Motor 2300 further includes an air gap thickness, which is the distance between the outer diameter of the rotor and the inner diameter of the stator.

[0179] In some embodiments, the plurality of windings 2315 are configured as concentrated windings (e.g., the opposite of distributed windings). For example, the plurality of windings 2315 are wound on only one of the plurality of stator teeth 2314. Compared to the distributed plurality of windings 2215 of the motor 2200, the plurality of windings 2315 configured as concentrated windings can include a smaller number of coils concentrated in a specific region of the stator 2305. This results in a simpler and more compact structure, and its manufacturing cost may be lower than that of distributed windings.

[0180] Motor 2300 includes a rotor 2317. Rotor 2317 includes a first slot 2320 and a second slot 2325. First slot 2320 includes a first arm 2321 and a second arm 2322, and a first magnet housing portion 2323 located between the first arm 2321 and the second arm 2322. Second slot 2325 includes a first arm 2326 and a second arm 2327, and a second magnet housing portion 2328 located therebetween. Motor 2300 may include a pair of first slots and second slots for each pole (e.g., four-pole, six-pole, etc.) of rotor 2317.

[0181] The rotor 2317 includes a circumferential outer surface 2318 spaced 2319 radially from the rotor's rotation center. In some embodiments, the first radial distance 2319 is no greater than 90% of the radius of the stator outer diameter. The first arm 2321 of the first slot 2320 includes a first width 2334 and a first length 2330. In some embodiments, the first width 2334 is between 2.5% and 200% of the magnet housing width 2335, and the first length 2330 is between twice the air gap thickness and 50% of the first radial distance 2319. The air gap thickness is the distance between the rotor outer diameter 2361 and the stator inner diameter 2362. The first magnet housing portion 2323 includes a first width 2350 and a first length 2340.

[0182] In some embodiments, the first width 2350 is between 0.5 and 10 times the air gap thickness, and the first length 2340 is greater than the stator tooth width. The first arm 2326 of the second slot 2325 includes a first width 2333 and a first length 2332. In some embodiments, the first width 2333 is between 2.5% and 200% of the magnet housing width 245, and the first length 2332 is between twice the air gap thickness and 50% of the first radial distance 2319. The second magnet housing portion 2328 includes a first length 2340 and a first width 2345. In some embodiments, the first width 2345 is between 0.5 and 10 times the air gap thickness, and the first length 2344 is greater than the stator tooth width.

[0183] In some embodiments, the first slot 2320 is referred to as the outer slot, and the second slot 2325 is referred to as the inner slot. In some embodiments, the first slot 2320 and the second slot 2325 are located at different radial distances from the rotation center of the rotor 2317. For example, the first slot 2320 is located at a second radial distance 2355 from the rotation center of the rotor 2317. In some embodiments, the second radial distance 2355 is not greater than 50% to 95% of the first radial distance 2319, and the second slot 2325 is located at a third radial distance 2360 from the rotation center. In some embodiments, the third radial distance is between 50% and 95% of the first radial distance 2319, wherein the second radial distance 2355 is greater than the third radial distance 2360.

[0184] The first magnet housing portion 2323 is configured to receive a magnet, such as magnet 2365. In some embodiments, magnet 2365 is configured to fill approximately 80% to 100% of the first magnet housing portion 2323. The second magnet housing portion 2228 is configured to receive a magnet, such as magnet 2370. In some embodiments, magnet 2370 is configured to fill approximately 100% of the second magnet housing portion 2328. In some embodiments, magnets 2365 and 2370 are rare-earth magnets (e.g., neodymium magnets). In some embodiments, each of motors 2200 and 2300 has approximately 10% less magnet mass compared to motor 2100.

[0185] Figure 24 This is a graphical representation of efficiency, current, and speed in revolutions per minute (“RPM”) compared to the torque output of several different motors in power tool 100, according to some embodiments. In some embodiments, the motor represented in graph 2400 is a core drill motor. Graph 2400 includes a representation of the efficiency of several different motors within power tool 100. Curve 2402 shows the efficiency of one type of motor in power tool 100 (such as motor 2100). Curve 2404 shows the efficiency of a second type of motor in power tool 100 (such as motor 2200). Curve 2406 shows the efficiency of a third type of motor in power tool 100 (such as motor 2300). In some embodiments, curve 2402 is the efficiency of motor 2100 as the torque value increases. In some embodiments, curve 2404 is the efficiency of motor 2300 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 2300 decreases at a faster rate than that of motor 2100. In some embodiments, curve 2406 represents the efficiency of motor 2300 as the torque value increases. In some embodiments, for a given torque value, the efficiency of motor 2200 decreases at a faster rate than that of motors 2100 and 2300.

[0186] Graph 2400 further includes a representation of the current of several different motors within the power tool 100. Curve 2410 shows the current of one type of motor in the power tool 100 (such as motor 2100). Curve 2412 shows the current of a second type of motor in the power tool 100 (such as motor 2200). Curve 2414 shows the current of a third type of motor in the power tool 100 (such as motor 2300). In some embodiments, curve 2410 represents the current level of motor 2100 as the torque value increases. In some embodiments, curve 2412 represents the current of motor 2200 as the torque value increases. In some embodiments, the currents of motors 2200 and 2300 are approximately equal for a given torque value as the torque increases. In some embodiments, curve 2414 represents the current of motor 2300 as the torque value increases. In some embodiments, the currents of motors 2100, 2200, and 2300 are approximately equal to each other as the torque increases, up to approximately 3.5 Nm of torque.

[0187] Graph 2400 further includes a representation of the RPM of several different motors within the power tool 100. Curve 2418 shows the RPM of one type of motor in the power tool 100 (such as motor 2100). Curve 2420 shows the RPM of a second type of motor in the power tool 100 (such as motor 2200). Curve 2422 shows the RPM of a third type of motor in the power tool 100 (such as motor 2300). In some embodiments, curve 2418 represents the RPM level of motor 2100 as the torque value increases. In some embodiments, curve 2420 represents the RPM of motor 2200 as the torque value increases. In some embodiments, as the torque increases, the RPM of motor 2200 starts at a higher level and then decreases for a given torque value at a faster rate than the RPM of motor 2100. In some embodiments, curve 2422 represents the RPM of motor 2300 as the torque value increases. In some implementations, as torque increases, the RPM of motor 2300 starts at a higher level and then decreases at a faster rate than that of motor 2100 for a given torque value. In some implementations, each motor operates at approximately the same speed for the workload 2450 of power tool 100.

[0188] Graph 2400 further includes a representation of the output power (in watts) of several different motors within the power tool 100. Curve 2428 shows the output power of one type of motor in the power tool 100 (such as motor 2100). Curve 2430 shows the output power of a second type of motor in the power tool 100 (such as motor 2200). Curve 2432 shows the output power of a third type of motor in the power tool 100 (such as motor 2300). In some embodiments, curve 2428 represents the output power level of motor 2100 as the torque value increases. In some embodiments, curve 2430 represents the output power level of motor 2200 as the torque value increases. In some embodiments, curve 2432 represents the output power level of motor 2300 as the torque value increases. In some embodiments, for the workload 2450 of the power tool 100, each motor 2100, 2200, and 2300 operates at approximately the same output power level. In the various embodiments described herein, the distance between two adjacent rotor arms is less than the magnet thickness. In the various embodiments described in this utility model, the distance between two adjacent arms is less than 200% of the magnet thickness. In the various embodiments described in this utility model, the plurality of stator windings can be configured as distributed windings or concentrated windings.

[0189] Furthermore, each rotor configuration described in this invention can be used with a distributed winding stator or a concentrated winding stator. In some embodiments, each rotor configuration can be used with a segmented stator or a non-segmented stator.

[0190] Therefore, the embodiments described in this utility model provide an electric tool including a permanent magnet assisted synchronous reluctance motor. Various features and advantages are recorded in the appended claims.

Claims

1. An electric tool, comprising: A battery pack interface configured to receive a removable and rechargeable battery pack; and A permanent magnet assisted synchronous rotor motor, characterized in that the permanent magnet assisted synchronous rotor motor comprises: Stator, the stator including a plurality of stator teeth configured to receive a plurality of stator coils, and Rotor, the rotor comprising: A first slot is located between the outer peripheral surfaces of the rotor. The first slot includes a first magnet housing portion having a first width and a first length. The first magnet housing portion is positioned at a first radial distance from the rotation center of the rotor. The second slot is located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion having a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a second radial distance from the rotation center of the rotor. A first magnet, the first magnet being within a first magnet housing portion, the first magnet having a first magnet length and a first magnet width; A second magnet, located within a second magnet housing, has a second magnet length and a second magnet width, and The first magnet fills at least 60% of the first magnet housing portion, and the second magnet fills at least 60% of the second magnet housing portion. The degree to which the first magnet fills the first magnet housing portion is at least as much as the degree to which the second magnet fills the second magnet housing portion.

2. The power tool as described in claim 1, characterized in that: The stator includes at least twelve stator slots; and The rotor includes at least four rotor poles.

3. The power tool as described in claim 1, characterized in that: The first magnet is made of ferrite metal material; and The second magnet is made of rare earth metal material.

4. The power tool as described in claim 1, characterized in that, The percentage by which the second magnet fills the second magnet housing portion is greater than the percentage by which the first magnet fills the first magnet housing portion.

5. The power tool as described in claim 1, characterized in that, Further includes: The first steel rib associated with the first slot; and The second steel rib associated with the second slot.

6. An electric tool, comprising: A battery pack interface configured to receive a removable and rechargeable battery pack; and A permanent magnet assisted synchronous rotor motor, characterized in that it comprises: Stator, the stator including a plurality of stator teeth configured to receive a plurality of stator coils; and Rotor, the rotor comprising: A first slot is located between the outer peripheral surfaces of the rotor. The first slot includes a first magnet housing portion having a first width and a first length. The first magnet housing portion is positioned at a first radial distance from the rotation center of the rotor. The second slot is located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion, which has a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a second radial distance from the rotation center of the rotor. A first magnet, the first magnet being within a first magnet housing portion, the first magnet having a first magnet length and a first magnet width; A second magnet, the second magnet being within a second magnet housing, the second magnet having a second magnet length and a second magnet width, and The first magnet fills between 60% and 90% of the first magnet shell portion, and the second magnet fills between 60% and 90% of the second magnet shell portion. The degree to which the first magnet fills the first magnet housing portion is at least as much as the degree to which the second magnet fills the second magnet housing portion.

7. The power tool as described in claim 6, characterized in that: The stator includes at least eighteen stator slots; and The rotor includes at least six rotor poles.

8. The power tool as described in claim 6, characterized in that: The stator includes at least six stator slots; and The rotor includes at least four rotor poles.

9. The power tool as described in claim 6, characterized in that: The first magnet is made of ferrite metal material; and The second magnet is made of rare earth metal material.

10. The power tool as claimed in claim 6, characterized in that, The first magnet and the second magnet are made of rare earth metal materials.

11. The power tool as claimed in claim 6, characterized in that, The percentage by which the second magnet fills the second magnet housing portion is greater than the percentage by which the first magnet fills the first magnet housing portion.

12. An electric tool, comprising: A battery pack interface configured to receive a removable and rechargeable battery pack; and A permanent magnet assisted synchronous rotor motor, characterized in that the permanent magnet assisted synchronous rotor motor comprises: The stator includes a plurality of stator teeth configured to receive a plurality of stator coils, and Rotor, the rotor comprising: A first slot is located between the outer peripheral surfaces of the rotor. The first slot includes a first magnet housing portion having a first width and a first length. The first magnet housing portion is positioned at a first radial distance from the rotation center of the rotor. The second slot is located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion, which has a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a second radial distance from the rotation center of the rotor. A first magnet, located within a first magnet housing portion, having a first magnet length and a first magnet width. A second magnet, located within a second magnet housing, has a second magnet length and a second magnet width. A first steel rib, configured to fill a portion of the first magnet housing. The second steel rib is configured to fill a portion of the second magnet housing portion, and The first magnet fills at least 60% of the first magnet housing portion, and the second magnet fills at least 60% of the second magnet housing portion. The degree to which the first magnet fills the first magnet housing portion is at least as much as the degree to which the second magnet fills the second magnet housing portion.

13. The power tool as claimed in claim 12, characterized in that: The first steel rib is positioned at the center of the first magnet housing portion; and The second steel rib is positioned at the center of the second magnet housing portion.

14. The power tool as claimed in claim 12, characterized in that: The power tool further includes a third steel rib and a fourth steel rib.

15. The power tool as claimed in claim 14, characterized in that: The first steel rib is configured to be positioned between the first arm of the first slot and the first magnet housing portion; The second steel rib is configured to be positioned between the second arm of the first slot and the first magnet housing portion; The third steel rib is configured to be positioned between the first arm of the second slot and the second magnet housing portion; and The fourth steel rib is configured to be positioned between the second arm of the second slot and the second magnet housing portion.

16. An electric tool, comprising: A battery pack interface configured to receive a removable and rechargeable battery pack; and A permanent magnet assisted synchronous rotor motor, characterized in that the permanent magnet assisted synchronous rotor motor comprises: The stator includes a plurality of stator teeth configured to receive a plurality of stator coils, and Rotor, the rotor comprising: The first radial distance from the rotation center of the rotor, wherein the first radial distance is not greater than 90% of the radius of the stator outer diameter; A first slot is located between the outer peripheral surfaces of the rotor. The first slot includes a first magnet housing portion having a first width and a first length. The first magnet housing portion is positioned at a second radial distance from the rotation center of the rotor. The second slot is located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion having a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a third radial distance from the rotation center of the rotor. A first magnet, the first magnet being within a first magnet housing portion, the first magnet having a first magnet length and a first magnet width; A second magnet, the second magnet being within a second magnet housing, the second magnet having a second magnet length and a second magnet width; and The first magnet fills between 30% and 90% of the first magnet shell portion, and the second magnet fills between 30% and 90% of the second magnet shell portion; Wherein, the second radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance, and the third radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance, and The second radial distance is greater than the third radial distance.

17. The power tool as claimed in claim 16, characterized in that: The first length is between approximately twice the air gap thickness and 50% of the first radial distance, and the first width is between approximately 2.5% and 200% of the magnet housing width. The second width is between 0.5 and 10 times the air gap thickness.

18. The power tool as claimed in claim 16, characterized in that: The first magnet fills 90% of the first magnet housing portion, and the second magnet fills 90% of the second magnet housing portion.

19. An electric tool, comprising: A battery pack interface configured to receive a removable and rechargeable battery pack; and A permanent magnet assisted synchronous rotor motor, characterized in that the permanent magnet assisted synchronous rotor motor comprises: The stator includes an inner diameter and a plurality of stator teeth configured to receive a plurality of stator coils, and Rotor, the rotor comprising: Air gap thickness, which includes the distance between the rotor outer diameter and the stator inner diameter; A first slot, the first slot including a first arm, a second arm and a first magnet housing portion positioned therebetween; The first arm includes a first length between twice the air gap thickness and 50% of the rotor radial distance, and a first width between 2.5% and 200% of the width of the first magnet housing portion. The second arm includes a second length between twice the air gap thickness and 50% of the rotor radial distance, and a second width between 2.5% and 200% of the width of the first magnet housing portion.

20. The power tool as claimed in claim 19, characterized in that, The rotor further includes: The second slot includes a third arm, a fourth arm, and a second magnet housing portion located therebetween. The third arm comprises a third length between twice the air gap thickness and 50% of the rotor radial distance, and a third width between 2.5% and 200% of the width of the second magnet housing portion. The fourth arm comprises a fourth length between twice the air gap thickness and 50% of the rotor radial distance, and a fourth width between 2.5% and 200% of the width of the second magnet housing portion.

21. The power tool as claimed in claim 19, characterized in that, The stator has a diameter of approximately 80 millimeters.

22. The power tool as claimed in claim 19, characterized in that, The maximum voltage of the rechargeable battery pack is approximately 83.5 volts.

23. The power tool as claimed in claim 19, characterized in that, The stator further includes stator slot filler for stator windings, the stator slot filler filling approximately 42% of the stator windings.

24. The power tool as claimed in claim 19, characterized in that, The permanent magnet assisted synchronous rotor motor further includes phase windings with resistance between 0.11 ohms and 0.15 ohms.

25. The power tool as claimed in claim 20, characterized in that, The rotor further includes: A first magnet, the first magnet being located within a first magnet housing portion, the first magnet being constructed of a ferrite metal material; and The second magnet is located inside the housing of the second magnet and is made of rare earth metal material.

26. The power tool as claimed in claim 20, characterized in that: The stator includes at least eighteen stator slots; and The rotor includes at least six rotor poles.

27. The power tool as claimed in claim 20, characterized in that: The stator includes at least six stator slots; and The rotor in question comprises at least four rotor poles.

28. An electric tool, comprising: A battery pack interface configured to receive a removable and rechargeable battery pack; and A permanent magnet assisted synchronous rotor motor, characterized in that the permanent magnet assisted synchronous rotor motor comprises: Stator, the stator comprising: A plurality of stator teeth, the plurality of stator teeth being configured to receive a plurality of stator coils; A plurality of stator winding slots, the plurality of stator winding slots including an outer stator winding periphery and an inner stator winding periphery that are offset from each other by stator winding radii, and A plurality of stator windings, the plurality of stator windings being configured to be wound around one or more stator teeth of the plurality of stator teeth; Rotor, the rotor comprising: The first radial distance from the rotation center of the rotor, wherein the first radial distance is not greater than 90% of the radius of the stator outer diameter; A first slot is located between the outer peripheral surfaces of the rotor. The first slot includes a first magnet housing portion having a first width and a first length. The first magnet housing portion is positioned at a second radial distance from the rotation center of the rotor. A first magnet, the first magnet being located within a first magnet housing portion; The first magnet fills between 80% and 100% of the first magnet shell portion.

29. The power tool as claimed in claim 28, characterized in that, The outer diameter of the motor is between 60 mm and 65 mm.

30. The power tool as claimed in claim 28, characterized in that, The motor has an outer diameter of 63 mm.

31. The power tool as claimed in claim 28, characterized in that, The plurality of stator windings are configured as distributed windings.

32. The power tool as claimed in claim 28, characterized in that, The plurality of stator windings are configured as concentrated windings.

33. The power tool as claimed in claim 28, characterized in that, The plurality of stator windings are configured to be evenly distributed around the periphery of the stator core.

34. The power tool as claimed in claim 28, characterized in that, The plurality of stator windings are configured to be distributed to reduce harmonic distortion within the permanent magnet assisted synchronous rotor motor.

35. The power tool as claimed in claim 28, characterized in that, The plurality of stator windings are configured in a distributed manner to achieve a uniform distribution of magnetic flux.

36. The power tool as claimed in claim 28, characterized in that, The rotor further includes: The second slot is located between the outer peripheral surface of the rotor and the first slot. The second slot includes a second magnet housing portion having a second width and a second length. The second length of the second slot is shorter than the first length of the first slot, and the second magnet housing is positioned at a third radial distance from the rotation center of the rotor. A second magnet is located within the housing portion of the first magnet. The second magnet fills between 80% and 100% of the first magnet shell portion. The second radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance, and the third radial distance from the rotation center of the rotor is between 50% and 95% of the first radial distance. The second radial distance is greater than the third radial distance.

37. The power tool as claimed in claim 36, characterized in that: The first magnet fills approximately 100% of the first magnet housing portion, and The second magnet fills approximately 100% of the second magnet housing portion.

38. The power tool as claimed in claim 36, characterized in that: The first magnet is made of ferrite metal material; and The second magnet is made of rare earth metal material.

39. The power tool as claimed in claim 36, characterized in that: The first slot further includes a first arm, a second arm, and the first magnet housing portion located therebetween. The first arm includes a first length between twice the air gap thickness and 50% of the rotor radial distance, and a first width between 2.5% and 200% of the width of the first magnet housing portion. The second arm includes a second length between twice the air gap thickness and 50% of the rotor radial distance, and a second width between 2.5% and 200% of the width of the first magnet housing portion.

40. The power tool as claimed in claim 39, characterized in that: The second slot further includes a third arm, a fourth arm, and a second magnet housing portion located therebetween. The third arm comprises a third length between twice the air gap thickness and 50% of the rotor radial distance, and a third width between 2.5% and 200% of the width of the second magnet housing portion. The fourth arm comprises a fourth length between twice the air gap thickness and 50% of the rotor radial distance, and a fourth width between 2.5% and 200% of the width of the second magnet housing portion.

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