Measurement of voltage sag of battery pack for identifying battery pack and controlling performance

Abstract

To solve the problem of the prior art.SOLUTION: A battery pack power supply device includes: an interface configured to receive a battery pack; a sensing circuit configured to detect voltage of the battery pack; and an electronic controller. The electronic controller is configured to receive a first signal from the sensing circuit indicating no-load voltage of the battery pack, determine threshold voltage based on no-load voltage, generate a control signal for driving en electric motor at a first operation parameter in response to activation of a trigger switch, receive a second signal from the sensing circuit, and update a control signal to drive the electric motor at a second operation parameter less than the first operation parameter in response to the second signal indicating that output voltage is below threshold voltage. The second signal indicates output voltage of the battery pack during operation of the electric motor.SELECTED DRAWING: Figure 1A

Description

[Technical field]

[0001] (Reference to Related Application) This application claims the benefit of U.S. Provisional Application No. 63 / 584,773, filed Sep. 22, 2023, the entire disclosure of which is incorporated herein by reference.

[0002] (Technical field) FIELD OF THE DISCLOSURE The present disclosure relates to power tools, and more particularly, to battery-powered tools. Summary of the Invention

[0003] Using a common interface format for power tool battery packs provides various technical and practical advantages. For example, a user may be able to easily swap battery packs between different tools without needing to have a specific battery pack for each tool. If a battery pack fails or runs out of charge, the battery pack can be quickly replaced with another battery pack, for example, from a different tool. Having a common interface format also allows different battery packs from different tools to be charged with the same charger. These improvements to interoperability greatly increase the flexibility of power tool systems. However, different battery packs may have different capabilities. These differences in capabilities may be due to design differences or may be due to natural degradation of battery cell chemistry or performance over time.

[0004] For example, battery packs of different capacities may have different internal resistances. Some higher capacity battery packs may have lower internal resistances than some lower capacity battery packs. Some higher capacity battery packs may have more active material in the electrodes, thicker electrodes, and / or electrodes with larger electrode surface area, which may reduce the internal resistance of the battery pack. Larger capacity battery packs may also have more cells arranged in parallel, which may also reduce the internal resistance of the battery pack. Larger capacity battery packs may also use higher quality electrolytes, which may also help reduce the internal resistance. As a function of lower internal resistance, a larger capacity battery pack may exhibit a lower voltage drop (also called voltage sag) in response to the same current draw demand than a lower capacity battery pack.

[0005] This voltage drop V may be expressed as a function of the battery pack's current draw I and internal resistance R according to Ohm's Law, i.e., equation (1) below:

number

[0006] As shown by equation (1), The voltage drop of the battery pack in response to current flow scales linearly as a function of the internal resistance. Thus, as described herein, a power tool (e.g., an electronic controller included in the tool) is configured to use the voltage drop exhibited by the battery pack in response to a given load (e.g., current) to determine the capacity of the battery pack and to optimize the control signals of the power tool based on the capacity of the battery pack.

[0007] Techniques that use voltage drop to determine the capacity of a battery pack (such as those described herein) may offer advantages over techniques that measure other characteristics (such as impedance), especially at low temperatures. For example, the impedance of a battery pack includes and / or is a function of both resistive components (e.g., resistance) and reactive components (e.g., chemical reactions within the battery pack). Because chemical reactions within the battery pack may tend to be slower at lower temperatures, the impedance of the battery cells tends to increase more than the impedance at lower temperatures. Because the voltage drop of a battery pack may be a function of the resistance of the battery pack, voltage drop-based techniques (such as those described herein) provide a more accurate assessment of battery pack capacity at lower temperatures than other impedance-based techniques.

[0008] According to some examples, a battery pack powered device, such as a power tool, includes a sensing circuit configured to detect a voltage of the battery pack and an electronic controller. The electronic controller is configured to receive a first signal indicative of an unloaded voltage of the battery pack from the sensing circuit, determine a threshold voltage based on the unloaded voltage, generate a control signal for driving an electric motor of the device in response to activation of a trigger switch, receive a second signal from the sensing circuit, and update the control signal in response to the second signal indicative of an output voltage below the threshold voltage. The second signal is indicative of an output voltage of the battery pack during operation of the electric motor. The control signal drives the electric motor to operate at a first operating parameter. The updated control signal drives the electric motor to operate at a second operating parameter. The second operating parameter is less than the first operating parameter.

[0009] In some aspects, the threshold voltage is determined as a percentage decrease of a nominal input voltage of the battery pack powered device. In some aspects, the decrease is about a 25% decrease. In some aspects, the nominal input voltage of the battery pack powered device is about 18 volts and the threshold voltage is about 13.5 volts. In some aspects, the control signal includes a first pulse width modulated signal and the updated control signal includes a second pulse width modulated signal, and a duty cycle of the first pulse width modulated signal is greater than a duty cycle of the second pulse width modulated signal.

[0010] In some embodiments, the first operating parameter is a first power output and the second operating parameter is a second power output, the first power output being greater than the second power output. In some embodiments, the first operating parameter is a first torque output and the second operating parameter is a second torque output, the first torque output being greater than the second torque output. In some embodiments, the first operating parameter is a first operating duration and the second operating parameter is a second operating duration, the first operating duration being greater than the second operating duration.

[0011] Another example provides a battery pack powered device, such as a power tool, including an electric motor, an interface configured to receive a battery pack, a sensing circuit configured to detect a voltage of the battery pack, and an electronic controller. The electronic controller is configured to initiate a test current draw from the battery pack, receive a first signal from the sensing circuit, select a first control mode for controlling the electric motor in response to the first signal indicating that the output voltage is not below a threshold, and select a second control mode for controlling the electric motor in response to the first signal indicating that the output voltage is below a threshold. The battery pack powers the electric motor. The first signal is indicative of the output voltage of the battery pack during the test current draw. The electronic controller is configured to generate a first control signal for controlling the electric motor in the first control mode. The electronic controller is configured to generate a second control signal for controlling the electric motor in the second control mode. The second control signal reduces an operating parameter of the electric motor compared to the first control signal.

[0012] In some embodiments, the threshold is determined as a percentage decrease in the designed output voltage of the battery pack. In some embodiments, the decrease is about a 25% decrease. In some embodiments, the designed output voltage of the battery pack is about 18 volts and the threshold is about 13.5 volts. In some embodiments, the first control signal is a pulse width modulated signal having a first duty cycle and the second control signal is a pulse width modulated signal having a second duty cycle, the first duty cycle being greater than the second duty cycle.

[0013] In some aspects, the first control signal controls the electric motor to operate at a first power output and the second control signal controls the electric motor to operate at a second power output, the first power output being greater than the second power output. In some aspects, the first control signal controls the electric motor to operate at a first torque output and the second control signal controls the electric motor to operate at a second torque output, the first torque output being greater than the second torque output. In some aspects, the first control signal controls the electric motor to operate for a first duration and the second control signal controls the electric motor to operate for a second duration, the first duration being greater than the second duration.

[0014] Some examples provide a method of operating a battery pack powered device, such as a power tool, that includes, in response to activation of a trigger switch, measuring with a controller a first voltage of a battery pack electrically connected to the device prior to application of a load associated with activation of the trigger switch and calculating with the controller a target voltage based on the first voltage. During application of the load associated with activation of the trigger switch, the method includes measuring a second voltage of the battery pack, comparing the second voltage to the target voltage, and modifying operation of the battery pack powered device in response to the second voltage being less than the target voltage.

[0015] In some aspects, calculating the target voltage includes decreasing the first voltage by a predetermined percentage. In some aspects, modifying operation of the battery pack powering device includes modifying a pulse width modulated control signal for an electric motor of the battery pack powering device. In some aspects, modifying operation of the battery pack powering device includes modifying operation of the battery pack powering device using a proportional integral control loop.

[0016] Other examples, embodiments, configurations, and aspects will become apparent by consideration of the detailed description and accompanying drawings.

[0017] Before describing any embodiment in detail, it should be understood that the embodiments are not limited in their application to the details of the arrangement and configuration of components set forth in the following description or illustrated in the accompanying drawings. The embodiments can be implemented or carried out in various ways. It should also be understood that the usage and terminology used herein is for descriptive purposes and should not be considered limiting. The use of "including," "comprising," or "having," and variations thereof, is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. Unless otherwise specified or limited in any other way, the terms "mounted," "connected," "supported," and "coupled," and variations thereof, are used broadly and encompass both direct and indirect mounting, connecting, supporting, and coupling.

[0018] Unless the context of usage clearly indicates otherwise, the articles "a," "an," and "the" should not be construed as meaning "one" or "only one." Rather, these articles should be construed as meaning "at least one" or "one or more." Similarly, unless the context of usage clearly indicates otherwise, when the terms "the" or "said" are used to refer to a noun previously introduced by the indefinite article "a" or "an," "the" and "said" mean "at least one" or "one or more."

[0019] In addition, it should be understood that the embodiments may include hardware, software, and electronic components or modules, which for purposes of discussion may be illustrated and described as if the majority of the components were implemented solely in hardware. However, those skilled in the art will recognize upon reading this detailed description that in at least one embodiment, electronic-based aspects may be implemented in software (e.g., stored in a non-transitory computer-readable medium) executable by one or more processing units, such as a microprocessor and / or an application-specific integrated circuit ("ASIC"). Thus, it should be noted that a number of hardware and software-based devices, as well as a number of different structural components, may be utilized to implement the embodiments. For example, a "server," "computing device," "controller," "processor," etc., as described herein may include one or more processing units, one or more computer-readable media modules, one or more input / output interfaces, and various connections (e.g., a system bus) connecting the components.

[0020] For example, relative terms, such as "about," "approximately," "substantially," and the like, used in connection with an amount or condition, are understood by those of skill in the art as including the stated value and have the meaning dictated by the context (e.g., the term includes at least the degree of error associated with the measurement precision, tolerances [e.g., manufacture, assembly, use, etc.] associated with the particular value). Such terms should also be considered as disclosing a range defined by the absolute values ​​of the two endpoints. For example, the phrase "about 2 to about 4" also discloses a range of "2 to 4." Relative terms may refer to plus or minus a percentage (e.g., 1%, 5%, 10%) of the indicated value.

[0021] While certain figures illustrate hardware and software located within certain devices, it should be understood that these depictions are for illustrative purposes only. Functionality described herein as being performed by one component may be performed by multiple components in a distributed manner. Similarly, functionality performed by multiple components may be integrated and performed by a single component. In some embodiments, the illustrated components may be combined or divided into separate software, firmware, and / or hardware. For example, instead of being located and performed within a single electronic processor, logic and processing may be distributed among multiple electronic processors. Regardless of how they are combined or divided, the hardware and software components may be located on the same computing device or distributed among different computing devices connected by one or more networks or other suitable communication links. Similarly, components described as performing certain functionality may also perform additional functionality not described herein. For example, a device or structure that is "configured" in a particular way may be configured in at least that way, but may also be configured in ways not explicitly recited.

[0022] Thus, in the claims, if an apparatus, 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 particular way, for example, to perform a plurality of functions, the claim or claimed subject matter should be construed to refer to one or more of such elements, in which case the one or more elements, in a set, collectively perform the plurality of functions, such that any one of the one or more elements is configured as claimed to perform any one or more of the recited functions, for example. [Brief description of the drawings]

[0023] [Figure 1A] 1 illustrates a battery pack according to certain embodiments described herein.

[0024] [Figure 1B] 1 illustrates a group of battery cells according to some embodiments described herein.

[0025] [Figure 2A] 1 illustrates a battery pack according to certain embodiments described herein.

[0026] [Figure 2B] 1 illustrates a group of battery cells according to some embodiments described herein.

[0027] [Diagram 3] 1A illustrates a device for determining the impedance of a battery pack, such as the battery pack of FIG. 1A or FIG. 2A, according to some embodiments described herein.

[0028] [Figure 4] 4 illustrates a control system for a device, such as the device of FIG. 3, according to some embodiments described herein.

[0029] [Diagram 5] 5 shows a circuit diagram for a field effect transistor (FET) switching module of the device of FIG. 4 according to some embodiments described herein.

[0030] [Figure 6A] 6 shows a circuit diagram illustrating current flow in a circuit, such as the circuit of FIG. 5, according to some embodiments described herein. [Figure 6B] 6 shows a circuit diagram illustrating current flow in a circuit, such as the circuit of FIG. 5, according to some embodiments described herein. [Figure 6C] 6 shows a circuit diagram illustrating current flow in a circuit, such as the circuit of FIG. 5, according to some embodiments described herein. [Figure 6D] 6 shows a circuit diagram illustrating current flow in a circuit, such as the circuit of FIG. 5, according to some embodiments described herein.

[0031] [Figure 7] 5 is a block diagram illustrating a power input module of the device of FIG. 4 according to certain embodiments described herein.

[0032] [Figure 8] 8 is a circuit diagram illustrating a voltage divider circuit of the power input module of FIG. 7 according to certain embodiments described herein.

[0033] [Figure 9A] 4 is a flowchart of a process for controlling an operational sequence of a battery-powered device, such as the device of FIG. 3, according to some embodiments described herein. [Figure 9B] 4 is a flowchart of a process for controlling an operational sequence of a battery-powered device, such as the device of FIG. 3, according to some embodiments described herein. [Figure 10A] 4 is a flowchart of a process for controlling an operational sequence of a battery-powered device, such as the device of FIG. 3, according to some embodiments described herein. [Figure 10B] 4 is a flowchart of a process for controlling an operational sequence of a battery-powered device, such as the device of FIG. 3, according to some embodiments described herein.

[0034] [Figure 11] 1 illustrates a block diagram of a process for implementing a control scheme and a graph showing the measured voltage of a battery pack as a function of time, according to certain embodiments described herein.

[0035] [Figure 12] FIG. 2 is a block diagram illustrating a feedback loop that may be used to implement a control scheme according to some embodiments described herein.

[0036] [Figure 13] 4 is a graph illustrating voltage drop of an exemplary first battery pack in response to a current load as a function of time.

[0037] [Figure 14] 14 is a graph illustrating the voltage drop of an exemplary second battery pack (having a lower capacity than the first battery pack of FIG. 13) in response to the same current load as a function of time.

[0038] [Figure 15] 1 is a graph showing the voltage of a battery pack as a function of load and illustrating the region where the controller generates an updated control signal (under a target voltage) according to certain embodiments described herein.

[0039] [Figure 16] 1 is a graph showing the power output of a motor of a battery powered device during an operating cycle implemented with a dynamic threshold update process and an operating cycle implemented without the dynamic threshold update process.

[0040] [Figure 17] FIG. 1 is a block diagram illustrating measurements and calculations that may be used to implement a control scheme in accordance with a dynamic threshold update process according to some embodiments.

[0041] In the drawings, reference numbers may be reused to identify similar and / or identical elements. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0042] 1A shows a battery pack 100. Battery pack 100 includes a housing 105, an optional user interface portion 110 for displaying a charge status for battery pack 100, and a device interface portion 115 for connecting (e.g., mechanically and electrically) battery pack 100 to a device (e.g., a power tool). Battery pack 100 includes a plurality of battery cells within housing 105.

[0043] 1B illustrates a group 125 of battery cells 120 that includes, for example, ten individual battery cells 120. The battery cells 120 can be disposed within a housing 105 of a battery pack 100. In some embodiments, the battery pack 100 includes more or less than ten battery cells within the housing 105.

[0044] 2A shows a battery pack 200 for powering a device (e.g., a power tool). The battery pack 200 includes a battery housing 230 and, referring to FIG. 2B, includes a plurality of battery cells 290.

[0045] FIG. 2B shows an interior view 245 of the battery housing 230. As shown in FIG. 2B, the battery housing 230 includes a wall 265 having an inner surface 280 and an outer surface 275. The inner surface 280 defines an interior cavity 270. The outer surface 275 includes a top portion 215 (FIG. 2A) and a bottom portion 285. With reference to FIG. 2B, the battery cells 290 disposed within the cavity 270 are connected in series to the battery contacts 205. With reference to FIG. 2A, a plurality of contacts 250 (FIG. 2B) are disposed within the battery contact housing extension 210 at the top portion 215. The housing extension 210 is configured to matingly engage with one or more power tools or powered accessories. A battery charge level indicator 220 may also be disposed on the housing (FIG. 2A), and additional battery charging, monitoring, and display components 255 may be disposed within the cavity 270 (FIG. 2B). As shown in FIG. 2A, two tabs 235 are coupled to the housing 230 for releasably securing the housing 230 to the power tool. Configurations corresponding to those described above with respect to the battery pack 200 may also be included in the battery pack 100. The battery packs 100 and 200 are provided as exemplary illustrations of battery packs, and it should be understood that the battery packs used as part of the embodiments described herein may take on various sizes and shapes and may include various numbers and types of battery cells and various numbers and types of tabs or other connection mechanisms for providing mechanical and electrical connections to a device (e.g., a power tool). It should also be understood that the battery packs used as part of the embodiments described herein may include additional or fewer components in various configurations, and the illustrated packs 100 and 200 are not limiting.

[0046] 3 illustrates device 300. In the embodiment illustrated in FIG. 3, device 300 is a power tool (e.g., drill / driver). In other embodiments, device 300 is a different type of power tool (e.g., impact wrench, ratchet, saw, hammer drill, impact driver, rotary hammer, grinder, blower, trimmer, etc.) or a different type of device (e.g., light, non-power sensing tool, etc.). Device 300 includes a housing 305 and an interface portion 310 for connecting device 300 to, for example, battery packs 100 and 200.

[0047] 4 illustrates a control system for device 300. The control system includes a controller 400. The controller 400 is electrically and / or communicatively connected to various modules or components of device 300. For example, the illustrated controller 400 is electrically connected to a motor 405 (e.g., an electric motor), a battery pack interface 410, a trigger switch 415 (connected to a trigger 420), one or more sensors or sensing circuits 425, one or more indicators 430, a user input module 435, a power input module 440, and a FET switching module 450 (e.g., including multiple switching FETs). The controller 400 includes a combination of hardware and software operable to, among other things, control operation of device 300 (e.g., control operation of motor 405), monitor operation of device 300, activate one or more indicators 430 (e.g., LEDs), etc.

[0048] The controller 400 includes a number of electrical and electronic components that provide power, operational control, and protection to the components and modules within the controller 400 and / or the device 300. For example, the controller 400 includes, among other things, a processing unit 455 (e.g., a microprocessor, a microcontroller, an electronic processor, an electronic controller, or another suitable programmable device), a memory 460, an input unit 465, and an output unit 470. The processing unit 455 includes, among other things, a control unit 475, an ALU 480, and a number of registers 485 (shown as a group of registers in FIG. 4 ) and is implemented using known computer architectures (e.g., modified Harvard architecture, von Neumann architecture, etc.). The processing unit 455, the memory 460, the input unit 465, and the output unit 470, as well as the various modules or circuits connected to the controller 400, are connected by one or more control buses and / or data buses (e.g., a common bus 490). The control buses and / or data buses are shown generally in FIG. 4 for purposes of illustration. The use of one or more control buses and / or data buses for interconnection and communication between the various modules, circuits, and components will be known to those of skill in the art in light of the embodiments described herein.

[0049] The memory 460 is a non-transitory computer-readable medium, and includes, for example, a program storage area and a data storage area. The program storage area and the data storage area can include a combination of different types of memory, such as ROM, RAM (e.g., DRAM, SDRAM, etc.), EEPROM, flash memory, hard disk, SD card, or other suitable magnetic, optical, physical, or electronic memory devices. The processing unit 455 is connected to the memory 460 and executes software instructions, which can be stored in the RAM of the memory 460 (e.g., during execution), in the ROM of the memory 460 (e.g., on a more or less permanent basis), or in another memory or another non-transitory computer-readable medium, such as a disk. Software included in the implementation of the device 300 can be stored in the memory 460 of the controller 400. The software includes, for example, firmware, one or more applications, program data, filters, rules, one or more program modules, and other executable instructions. The controller 400 is configured to retrieve from the memory 460 and execute instructions related to, among other things, the control processes and methods described herein. In other configurations, the controller 400 includes additional components, fewer components, or different components.

[0050] The battery pack interface 410 includes a combination of mechanical (e.g., rails, grooves, latches, etc.) and electrical (e.g., one or more terminals) components configured and operable to interface (e.g., mechanically, electrically, and optionally communicatively connect) the device 300 with a battery pack (e.g., battery packs 100, 200). For example, power provided to the device 300 by the battery pack 100 is provided to the power input module 440 through the battery pack interface 410. The power input module 440 includes a combination of active and passive components to regulate or control the power it receives from the battery pack 100 before the power is provided to the controller 400. The battery pack interface 410 also provides power to the FET switching module 450 to provide power to the motor 405. The battery pack interface 410 may also include a communication line 495 to provide a communication link between the controller 400 and the battery pack 100, for example.

[0051] Indicator 430 may include, for example, one or more light emitting diodes ("LEDs"). Indicator 430 can be configured to display a status of device 300 or information related to device 300. For example, in some embodiments indicator 430 is configured to indicate a measured electrical characteristic of device 300, a status of device 300, etc.

[0052] A user input module 435 is operably coupled to the controller 400, for example, to select a forward or reverse operating mode, a torque and / or speed setting for the device 300 (e.g., using torque and / or speed switches), or other operation of the device 300. In some embodiments, the user input module 435 includes one or more digital input devices, one or more digital output devices, one or more analog input devices, one or more analog output devices, or a combination, such as, for example, one or more knobs, one or more dials, one or more switches, one or more buttons, etc. In some embodiments, the user input module 435 includes a touch screen that can be used as an input device, an output device, or a combination thereof.

[0053] In some embodiments, the controller 400 is configured to determine whether a fault condition of the device 300 exists and generate one or more control signals associated with the fault condition. For example, the sensing circuit 425 may include one or more current sensors, one or more speed sensors, one or more Hall effect sensors, one or more temperature sensors, or a combination thereof, and the controller 400 is configured to process data received from the sensing circuit 425 to determine whether a fault condition exists. For example, the controller 400 may be configured to compare data received by the sensing circuit 425 (e.g., in raw form, processed form, or a combination thereof) to one or more predefined operational thresholds or limits that the controller 400 may calculate or access (e.g., in memory 460). For example, when a potential thermal failure (e.g., of the FET, motor 405, etc.) is detected or predicted by the controller 400, the controller 400 may be configured to limit or interrupt power provided to the motor 405 from an interfaced battery pack until, for example, the likelihood of a thermal failure is reduced or the device 300 is reset. In some embodiments, controller 400 is configured to provide information and / or control signals to another component of device 300 (e.g., indicator 430), to battery pack 100 or 200 (e.g., via battery pack interface 410), or to a combination thereof, in response to detecting one or more such fault conditions of device 300 or determining that a fault condition of device 300 no longer exists. As described in more detail with respect to FIGS. 9A, 9B, 10A, and 10B, in some embodiments, controller 400 uses sensing circuit 425 to determine a capacity (e.g., internal impedance) of a body pack interfaced with device 300 in addition to or as an alternative to using sensing circuit 425 to detect a fault condition.

[0054] In various implementations, the FET switching module 450 may be connected to or may be part of an inverter 451 that provides alternating current (AC) power to the motor 405. For example, the battery pack interface 410 may be connected to a direct current (DC) bus 452, which may be connected to the inverter 451 and / or the FET switching module 450. The battery pack interface 410 may provide DC power to the DC bus 452. The DC bus 452 may provide DC power to the inverter 451. The inverter 451 may include a switching device, such as the FET switching module 450, and may control the switching device to generate an AC waveform from the source DC power. The inverter 451 may provide the AC waveform as AC power to drive the motor 405. As shown in FIG. 4, in some examples, the controller 400 may be connected to the inverter 451 and / or the DC bus 452 to monitor and / or control the inverter 451 and / or the DC bus 452.

[0055] 5 shows a circuit diagram 500 of a FET switching module 450. The FET switching module 450 includes a plurality of high-side power switching elements 502 and a plurality of low-side power switching elements 504. In some embodiments, the controller 400 provides control signals to control the high-side FETs 502 and the low-side FETs 504 to drive the motor 405. For example, in response to detecting activation of the trigger 420, the controller 400 provides one or more control signals to selectively enable and disable the FETs 502 and 504 (e.g., sequentially, in pairs) to cause power from a power source 510 (e.g., one of the battery packs 100 and 200 interfaced with the device 300) to be selectively applied to a stator coil of the motor 405 to cause rotation of the rotor. More specifically, to drive the motor 405, the controller 400 enables a first high-side FET 502 and a first low-side FET 504 pair (e.g., by providing a voltage at the gate terminals of the FETs) for a first period of time. In response to determining that the rotor of the motor 405 has rotated based on pulses from the sense circuit 425, the controller 400 disables the first FET pair and enables the second high-side FET 502 and the second low-side FET 504. In response to determining that the rotor of the motor 405 has rotated (e.g., based on pulses from the sense circuit 425), the controller 400 disables the second FET pair and enables the third high-side FET 502 and the third low-side FET 504. This sequence of periodically enabling the high-side FET 502 and low-side FET 504 pairs is repeated to drive the motor 405. Further, in some embodiments, the control signal includes a pulse width modulated (PWM) signal having a duty cycle set proportional to the amount of trigger pull of trigger 420, thereby controlling the speed or torque of motor 405. It should be understood that device 300 may include different configurations for controlling power from power supply 510 to motor 405, and FET 504 and related components are provided as one non-limiting example.

[0056] For example, Figure 6A illustrates a current flow diagram 600 of a FET switching module 450. The FET switching module 450 includes a plurality of high side power switching elements 502 and a plurality of low side power switching elements 504, as described above. For example, in response to detecting a pull of the trigger 420, the controller 400 provides one or more control signals to selectively enable and disable the FETs 502 and 504 (e.g., sequentially, in pairs) resulting in power being provided from a power source 510 (e.g., battery pack 100, 200). A current 610 travels from the power source 510 through one of the high side power switching elements 502 to a stator coil of the motor 405. The current 610 then travels from the motor 405 to one of the low side power switching elements 504 before completing a connection path 615 of the power source 510.

[0057] 6B illustrates another current flow diagram 620 of the FET switching module 450. The FET switching module 450 includes multiple high-side power switching elements 502 and multiple low-side power switching elements 504, as described above. For example, in response to detecting a pull of the trigger 420, the controller 400 provides one or more control signals to selectively enable and disable the FETs 502 and 504 (e.g., sequentially, in pairs) to result in power being provided from the power source 510 (e.g., battery pack 100, 200). A current 610 travels from the power source 510 through one high-side power switching element 502 to one low-side power switching element 504. The current 610 then completes the circuit by returning to the power source 510. This reduced current 610 path travels only through two switching FETs, completing a short portion of the connection path 615 of the power source 510. In some aspects, one or more high-side power switching elements 502 and / or one or more low-side power switching elements 504 are enabled simultaneously. Such control may reduce the overall resistance of the system, allowing higher current flow and distributing the system load across FETs 502 and 504, reducing the burnup of FETs 502 and 504.

[0058] FIG. 6C also illustrates another current flow diagram 625 of the FET switching module 450. In this example, an additional switching module 630 is connected to the connection path 615. In addition to the additional switching module 630, an additional resistor is connected to the connection path 615. For example, in response to detecting the pull of the trigger 420, the controller 400 provides one or more control signals to selectively enable and disable the switching module 630 to provide power from the power source 510 (e.g., battery pack 100, 200). The current 610 travels from the power source 510 through the additional resistor and then through the additional switching module 630. In this example, the current 610 only travels through the additional resistor and the additional switching module 630 before returning to the power source 510 to close the circuit. In other embodiments, an inductor can be used for a similar purpose as the additional resistor. In addition, other circuitry configurations can be configured in such a way that other components (e.g., capacitors) can be used.

[0059] 6D illustrates yet another current flow diagram 635 of the FET switching module 450. In this example, only one power switching module 504 is used. For example, in response to detecting the pull of the trigger 420, the controller 400 provides one or more control signals to selectively enable and disable the power switching element 504 to result in power being provided from the power source 510 (e.g., battery pack 100, 200). Current 610 travels from the power source 510 to the motor 405 (e.g., a brushed motor) and the power switching element 504 before closing the connection path 615.

[0060] Again, the embodiments described herein may be used with various types of battery packs and battery-powered devices, and the details provided in FIGS. 1-6D are provided as non-limiting illustrative examples.

[0061] FIG. 7 is a block diagram illustrating a power input module 440 according to some embodiments. In various embodiments, the power input module 440 includes a voltage divider circuit 702 and an analog-to-digital converter 704. The inputs of the voltage divider circuit 702 may be coupled to the positive and negative terminals of the battery pack interface 410. The voltage divider circuit 702 may step down the output voltage of a battery pack connected to the battery pack interface 410 (such as the battery pack 100 or the battery pack 200) and output the stepped-down voltage to the analog-to-digital converter 704. The analog-to-digital converter 704 converts the analog step-down voltage signal to a digital signal and outputs the digital signal to the controller 400. As described in more detail with respect to FIG. 8, the controller 400 may determine the output voltage of the battery pack connected to the battery pack interface 410 based on the digital signal output from the analog-to-digital converter 704. For example, in an example in which the power input module 440 includes a voltage divider circuit 702, the controller 400 may determine the actual voltage of the battery pack based on a stepped-down voltage output from the voltage divider circuit 702 to the analog-to-digital converter 704 according to a voltage divider equation appropriate for the voltage divider circuit 702.

[0062] 8 is a circuit diagram illustrating a voltage divider circuit 702 according to some embodiments. As shown in FIG. 8, some implementations of the voltage divider circuit 702 include a first input terminal 802 and a second input terminal 804, and a first resistor 806 and a second resistor 808 arranged in series between the first input terminal 802 and the second input terminal 804. A first output terminal 810 may be connected to a first node between the first resistor 806 and the second resistor 808, and a second output terminal 812 may be connected to a second node between the second input terminal 804 and the second resistor 808. In some embodiments, a battery pack (represented by a battery 814 in FIG. 8, which may include a battery pack 100 or 200 described herein) may be connected to the first input terminal 802 and the second input terminal 804. For example, the positive terminal of the battery 814 may be connected to the first input terminal 802, and the negative terminal of the battery 814 may be connected to the second input terminal 804. Thus, the input voltage V in may be applied across the first resistor 806 and the second resistor 808. The first resistor 806 and the second resistor 808 may be connected in series such that the input voltage V in may be divided between the first resistor 806 and the second resistor 808 according to the resistance R1 of the first resistor 806 and the resistance R2 of the second resistor 808.

[0063] In the example where the first output terminal 810 and the second output terminal 812 are connected across the second resistor 808, the output voltage V of the voltage divider circuit 702 (measured across the first output terminal 810 and the second output terminal 812) is out may be expressed according to the following voltage divider equation (2), which is derived from Ohm's law and the voltage division principle:

number

[0064] The relationship between the resistors in the voltage divider equation (2) above may be expressed as a transfer function H shown in equation (3) below.

number

[0065] Thus, as described in more detail with respect to FIG. 8, the controller 400 determines (V out Based on the voltage output from the voltage divider circuit 702 (represented by V in The voltage of the battery 814 (represented by

number

[0066] Although the voltage divider circuit 702 is shown as having two resistors and the transfer function H is expressed as a function of two resistors, it should be understood that the voltage divider circuit 702 may include any number of resistors and the transfer function H may be any suitable value.

[0067] 9A-9B are flowcharts of a process 900 for controlling an operational sequence of the device 300 according to some embodiments, and in particular depict a process for determining characteristics (e.g., capacity, impedance, etc.) of a battery pack electrically connected to the device 300 based on measured voltages, and using the determined characteristics to generate one or more control signals for controlling the motor 405. Although the operations of the process 900 are illustrated with reference to specific examples described herein, the process 900 may be implemented in any suitable configuration. Although the operations are shown in FIGS. 9A-9B once each and in a particular order, the operations may be reordered and / or repeated as desired and appropriate. For example, different operations may be performed in parallel as appropriate. In various implementations, a battery pack having a higher capacity may exhibit a lower (smaller) voltage drop in response to a given current draw than a battery pack having a lower capacity. Thus, the voltage drop of the battery pack in response to a given current draw may be used to determine the capacity of the battery pack connected to the device 300, and the controller 400 may operate the device 300 according to a control mode optimized for the capacity of the battery pack. For example, in response to determining that the battery pack is a higher capacity battery pack, the controller 400 may control the motor 405 to operate at a higher operating parameter. In contrast, in response to determining that the battery pack is a lower capacity battery pack, the controller 400 may control the motor 405 to operate at a lower operating parameter. In various embodiments, the operating parameter may be the speed of the motor 405. In some embodiments, the operating parameter may be the power output (e.g., torque output τ×angular velocity ω) of the motor 405. In some examples, the operating parameter may be the torque output of the motor 405. In various implementations, the operating parameter may be the run time (operation duration) of the motor.

[0068] In block 902, the controller 400 measures a no-load voltage signal of a battery pack connected to the device 300 (such as the battery pack 100 or 200 connected to the interface portion 310). For example, the voltage divider circuit 702 may step down the no-load voltage of the battery pack taken across the positive and negative terminals of the battery pack at the battery pack interface 410 when the battery pack has no current load (or has a minimal current load). The analog-to-digital converter 704 may convert the analog no-load voltage of the battery pack to a digital no-load voltage signal and output the digital no-load voltage signal to the controller 400. In block 904, the controller 400 determines the no-load voltage of the battery pack based on the digital no-load voltage signal. In various implementations, the no-load voltage signal represents a stepped-down no-load voltage output from the voltage divider circuit 702, and the controller 400 converts the stepped-down no-load voltage to the no-load voltage of the battery pack according to a transfer function of the voltage divider circuit 702 (e.g., as described above with reference to Figures 7 and 8).

[0069] At block 906, the controller 400 determines a threshold value based on the no-load voltage of the battery pack. In various implementations, the threshold value may be set as a percentage of the no-load voltage. For example, the threshold value may be set as a percentage of the no-load voltage and may define a target voltage, where a measured voltage drop above the target voltage indicates a high capacity battery pack and a measured voltage drop below the target voltage indicates a low capacity battery pack. In various implementations, the threshold value may be set to a value of about 15%, 20%, 25%, 30%, 35%, or 40% (or other values ​​between the range of about 15% and about 40%). However, in some implementations, the threshold is set to other values, such as, for example, about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90% or 95% of the no-load voltage, or various values ​​therebetween. In some embodiments, rather than calculating the threshold from measurements, the controller 400 may be preprogrammed with the threshold, which may be stored and associated with the threshold (e.g., through a look-up table or other data structure or data mapping mechanism). Thus, the controller 400 may determine the threshold by retrieving the appropriate threshold from memory after determining the no-load voltage. Also, in some embodiments, the controller 400 may determine the no-load voltage of the battery pack based on other values, such as data communicated between the device 300 and the connected battery pack, stored voltage settings for the device 300, or a combination thereof. For example, the thresholds may be set as a percentage of the nominal voltage of the battery pack and / or the nominal voltage of the device 300. The nominal voltage may be the voltage that the battery pack is designed to output in normal operation and / or the voltage that the device 300 is designed to receive from the battery pack in normal operation. For example, if the nominal voltage of the battery pack and / or the device 300 is about 18 volts, the thresholds may be set according to Table 1 below. [Table 1]

[0070] The controller 400 may be configured to determine the thresholds without measuring the no-load voltage of the battery pack, although measuring this voltage may allow the controller 400 to set appropriate thresholds based on the current condition of the battery pack.

[0071] In various implementations, the thresholds, the percentage decrease from the nominal voltage, and / or the percentage decrease from the no-load voltage can be set based on empirical data for a particular type of device and one or more loads (or ranges of loads). In some embodiments, the empirical data may include different operating applications or environments of the device 300, which may be used to establish the adjusted thresholds. The controller 400 may be configured to adjust (e.g., increase or decrease) the thresholds based on the current operating application or environment of the device 300 (e.g., based on a measured temperature, an operating mode of the device 300, accessories installed on the device 300, etc.).

[0072] At block 908, the controller 400 monitors the trigger switch 415 for activation. Although the process 900 shows the thresholds being set prior to activation of the trigger switch 415 (e.g., as part of an initialization or configuration process of the device 300), it should be understood that in some embodiments (see, e.g., FIG. 12 and related description), the threshold determinations described with respect to blocks 902-906 may occur after the trigger switch 415 is activated but before a load is applied to the battery pack associated with the trigger activation. Measuring the no-load voltage in time for application of the load may result in increased optimization of the battery pack because more accurate thresholds may be set based on the current state of the battery pack.

[0073] As mentioned above, the trigger switch 415 may be connected to the trigger 420, and the trigger 420 may actuate the trigger switch 415. In various implementations, the trigger switch 415 may include an on-off switch, and actuation of the trigger 420 closes the on-off switch. In some embodiments, the trigger switch 415 may include a variable resistor, such as a potentiometer. The variable resistor may change the resistance of the trigger switch 415 based on the position of the trigger 420, which in turn changes the voltage and / or current of the signal output from the trigger switch 415 based on the position of the trigger 420. In some examples, the trigger switch 415 may include a Hall effect sensor. The Hall effect sensor may be used to detect the position of the trigger 420, and the voltage and / or current of the signal output from the trigger switch 415 may be adjusted based on the position of the trigger 420.

[0074] At decision block 910, the controller 400 determines whether the trigger switch 415 has been activated. In response to a determination that the trigger switch 415 has not been activated ("NO" at decision block 910), the controller 400 continues to monitor the trigger switch for activation at block 912, and the process 900 returns to decision block 910. In response to the controller 400 determining that the trigger switch 415 has been activated ("YES" at decision block 910), the controller 400 generates one or more control signals for the motor 405 of the device 300 at block 914. In various implementations, the control signal may be an analog signal, such as a voltage signal (e.g., a continuous signal that may control a parameter of the motor 405 using a change in voltage) or a current signal (e.g., a continuous signal that may control a parameter of the motor 405 using a change in current). In some examples, the control signal may be a digital signal, such as a pulse width modulated (PWM) signal. In examples where the control signal is a PWM signal, the duty cycle (e.g., the ratio of on time to the total period of the signal) may be modulated to control operating parameters of the motor 405. In various embodiments, the operating parameters of the motor 405 may include the speed, power, torque, and / or run time of the motor 405.

[0075] At block 916, the controller 400 controls the motor 405 using the generated control signal. For example, in implementations where the control signal is a PWM signal, the controller 400 may provide the control signal to the FET switching module 450, which may drive the motor 405 based on the control signal to apply a load to a battery pack electrically connected to the device 300. At block 918, the controller 400 monitors the output voltage of a battery pack connected to the battery pack interface 410 (such as the battery pack 100 or 200) due to the application of the load. For example, the controller 400 monitors the digital signal output from the analog-to-digital converter 704. At block 918, the controller 400 determines the output voltage of the battery pack connected to the battery pack interface 410. For example, the controller 400 calculates the output voltage of the battery pack based on the digital signal output from the analog-to-digital converter 704 according to the techniques described above with reference to FIG. 7 and FIG. 8.

[0076] At decision block 922, the controller 400 determines whether the battery pack output voltage is below a threshold value. As described herein, in various implementations, the threshold value may be dynamically determined by the controller 400 (e.g., according to the process described above with reference to blocks 902-906). In other embodiments, the controller 400 may be pre-programmed with the threshold value (e.g., as described above with reference to process 900 and / or Table 1). In response to a determination that the battery pack output voltage is not below the threshold value ("NO" at decision block 922), the controller 400 continues to monitor the battery pack output voltage (e.g., by monitoring the digital signal output from the analog-to-digital converter 704) at block 924, and the process 900 returns to block 920. In response to a determination that the battery pack output voltage is below the threshold value ("YES" at decision block 922), the controller 400 generates an updated control signal at block 926. For example, the updated control signal may reduce an operating parameter (e.g., speed, power, torque, and / or run time) of the motor 405 relative to the control signal generated in block 914. In various implementations, the control signal may be an analog control signal used to drive the motor 405, and the updated control signal generated in block 926 may have a reduced voltage, current, and / or duration compared to the control signal generated in block 914. In some examples, the control signal may be a PWM control signal provided to the FET switching module 450, and the updated control signal generated in block 926 may have an inverted duty cycle compared to the control signal generated in block 914. In some examples, the controller 400 may reduce the duration for which the control signal is provided to the motor 405. At block 928, the controller 400 provides the updated control signal to the motor 405 (e.g., via the FET switching module 450). From block 928, the process 900 proceeds to block 924.

[0077] It should be appreciated that the threshold determination portion of process 900 may be performed as part of an initialization process, for example, when device 300 is powered on or reset. Thus, the determined thresholds may be used in response to one or more trigger activations as shown in process 900 while device 300 is operational (e.g., until device 300 is powered off or hibernated). However, in other embodiments, the threshold determination portion of process 900 may be repeated in response to a requesting user, a particular input, operation, or state of device 300 at a predetermined frequency, or a combination thereof.

[0078] It should also be understood that measuring and monitoring the voltage of the battery pack during application of the load may be performed while the trigger is activated, for a predetermined amount of time after initial activation, or until a predetermined condition or event occurs, or a combination thereof. For example, in some embodiments, a voltage sag may occur within an initial time after the trigger is activated, and thus voltage measurements may be performed for a limited time after the trigger activation.

[0079] 9A-9B provide various technical advantages to a battery pack powered device. For example, the controller 400 may dynamically determine characteristics (such as capacity, impedance, etc.) of a battery pack connected to the device 300 and dynamically adjust control signals used to control the motor 405 such that operating parameters (such as speed, power, torque, and / or runtime) of the motor 405 are optimized based on the characteristics of the battery pack, which may improve performance of the battery pack and / or the device 300. For example, the controller 400 may detect when one or more operating parameters of the motor 405 exceed an optimal performance envelope of the battery pack (e.g., by causing excessive voltage drop across the battery pack) and may generate updated operating parameters to guide operation of the motor 405 within the optimal performance envelope of the battery pack.

[0080] 10A-10B are flowcharts of a process 1000 for controlling an operational sequence of device 300 according to some embodiments, particularly depicting determining characteristics (e.g., capacity, impedance, etc.) of a battery pack connected to device 300 via a measured voltage (e.g., voltage drop) and using the determined characteristics to generate one or more control signals for controlling motor 405. Although the operations of process 1000 are illustrated with reference to specific examples described herein, process 1000 may be implemented in any suitable configuration. Although the operations are illustrated in FIGS. 10A-10B once each and in a particular order, the operations may be reordered and / or repeated as desired and appropriate. For example, different operations may be performed in parallel as appropriate. In various implementations, while the process 900 described above monitors the battery pack as it drives the motor 405 and dynamically adjusts the operating parameters of the motor 405 during operation, the process 1000 may test the battery pack prior to operation and pre-select an optimized operating mode for the battery pack (e.g., based on determined characteristics of the battery pack). The selected operating mode may then be applied (e.g., when a trigger is activated), for example, without measuring and monitoring the voltage drop that occurs after the trigger activation.

[0081] As shown in FIG. 10A, in block 1002, the controller 400 measures a no-load voltage signal of a battery pack connected to the device 300 (such as the battery pack 100 or 200 connected to the interface portion 310). In various embodiments, the controller 400 measures the no-load voltage signal as described above with reference to block 902. In block 1004, the controller 400 determines a no-load voltage of the battery pack based on the no-load voltage signal (e.g., as described above with reference to block 904). In block 1006, the controller 400 determines a threshold value based on the no-load voltage of the battery pack (e.g., as described above with reference to block 906). In various implementations, the controller 400 may be pre-programmed with a threshold value (as described above with reference to process 900 and FIGS. 9A-9B).

[0082] At block 1008, the controller 400 initiates a test current draw from a battery pack connected to the battery pack interface 410 (such as battery pack 100 or 200). At block 1010, the controller 400 monitors the output voltage of the battery pack during the test current draw. For example, the controller 400 monitors the digital signal output from the analog-to-digital converter 704. At block 1012, the controller 400 determines the output voltage of the battery pack during the test current draw. For example, the controller 400 calculates the output voltage of the battery pack based on the digital signal output from the analog-to-digital converter 704 according to the techniques described above with reference to FIGS. 7 and 8. At decision block 1014, the controller 400 determines whether the output voltage of the connected battery pack is less than a threshold value. In various implementations, the threshold value may be any of the threshold values ​​described above with reference to decision block 922 of the process 900. In response to a determination that the battery pack output voltage is not below the threshold value (“NO” at decision block 1014), the controller 400 selects a first operating mode at block 1016 and process 1000 proceeds to block 1018. In response to a determination that the battery pack output voltage is below the threshold value (“YES” at decision block 1014), the controller 400 selects a second operating mode at block 1020 and process 1000 proceeds to block 1018. The first operating mode may be associated with a first battery pack capacity (or capacity range) and the second operating mode may be associated with a second, lower battery pack capacity (or capacity range).

[0083] After selecting the operating mode at block 1018, the controller 400 monitors the trigger switch 415 for activation of the trigger switch 415. At decision block 1022, the controller 400 determines whether the trigger switch 415 has been activated. In response to a determination that the trigger switch has not been activated ("NO" at decision block 1022), the controller 400 continues monitoring the trigger switch 415 at block 1024, and the process 1000 returns to decision block 1022. In response to a determination that the trigger switch has been activated ("YES" at decision block 1022), the controller 400 generates (at block 1026) a control signal for the motor in accordance with the selected control mode. In response to the first control mode being selected, the controller 400 generates a control signal to control the motor 405 at baseline operating parameters (such as, for example, baseline speed, power, torque, and / or runtime). In response to the second mode being selected, the controller 400 generates updated or modified control signals to control the motor 405 at reduced operating parameters relative to the baseline operating parameters.

[0084] In various implementations, the baseline operating parameter may include a first speed and the reduced operating parameter may include a second speed that is less than the first speed. In some examples, the baseline operating parameter may include a first power and the reduced operating parameter may include a second power that is less than the first power. In some embodiments, the baseline operating parameter may include a first torque and the reduced operating parameter may include a second torque that is less than the first torque. In various implementations, the baseline operating parameter may include a first runtime and the reduced operating parameter may include a second runtime having a duration less than the first runtime. At block 1028, the controller 400 provides a control signal to the motor 405 (e.g., via the FET switching module 450).

[0085] It should be understood that in some embodiments, more than two control modes may be used, and each control mode may be associated with a different control signal for the motor 405. When more than two control modes are used, more than two thresholds (e.g., different thresholds to identify different voltage drops) may be used to determine the appropriate control mode given the capacity of the connected battery pack.

[0086] The controller 400 may repeat the control mode selection portion of the process 1000 in response to a particular condition or input according to a predetermined frequency, or a combination thereof. For example, the controller 400 may be configured to repeat the control mode selection portion of the process 1000 upon each power-up or reset of the device 300, after a predetermined period of time, or a combination thereof.

[0087] Thus, similar to process 900, the control scheme implemented in accordance with process 1000 provides various technical advantages for battery pack powered devices. Also, using a test current draw allows a control mode to be initially set for device 300, which may simplify motor control after trigger activation (e.g., by reducing the need for voltage measurement and monitoring compared to process 900).

[0088] Also, in some examples, the controller 400 may be programmed to implement process 900, process 1000, or both processes 900 and 1000. Also, in some implementations, the controller 400 may be programmed to combine aspects of processes 900 and 1000 in various ways. For example, in some implementations of process 1000, the controller 400 may be configured to omit block 1008 (test current draw) and execute blocks 1012-1020 after an initial activation of the trigger switch 415 (e.g., after the controller 400 detects that the trigger switch 415 was at decision block 1022 after a first time point). In such examples, the controller 400 monitors the voltage signal output from the analog-to-digital converter 704 when the battery pack drives the motor 405 at block 1010 (instead of monitoring the voltage signal during test current draw) and selects an appropriate control mode for subsequent operation of the device 300. Thus, in this implementation, a control mode can be selected during one activation of the trigger (e.g., the first activation after the device 300 is turned on), which may reduce or eliminate the need to implement test current draw and may reduce or eliminate the need to measure and monitor the battery pack voltage during subsequent trigger activations.

[0089] Also, as described with respect to Figures 9A and 9B, in some examples, the threshold value is determined in response to activation of a device trigger, rather than as part of an initialization or configuration process of the device 300. For example, Figure 11 is a block diagram illustrating a process 1100 for implementing a control scheme according to process 900 of Figures 9A-9B and / or process 1000 of Figures 10A-10B, and a graph 1105 illustrating a measured voltage of the battery pack as a function of time. As shown in Figure 11, hardware (e.g., controller 400) may measure the voltage of the battery pack at a state of charge ("SoC voltage") in response to detecting activation (e.g., pulling) of trigger 420, but prior to application of a load associated with the trigger activation. For example, the SoC voltage may be a no-load voltage determined as described above with reference to process 900 and Figures 9A-9B and / or process 1000 and Figures 10A-10B. The hardware may calculate a target voltage according to the SoC voltage. For example, as described above, the target voltage may be a threshold value and may be calculated as described above with reference to process 900 and / or FIGS. 9A-9B and / or process 1000 and / or FIGS. 10A-10B. After the target voltage is calculated, the hardware uses the target voltage to adjust the device (e.g., tool) operation (such as the operating parameters of the motor 405 as described with respect to processes 900 and 1000). As shown in graph 1105, the hardware may control the motor 405 to operate at a first operating parameter when the measured voltage of the battery pack is above the target voltage and at a second operating parameter less than the first operating parameter when the measured voltage of the battery pack is below the target voltage. For example, in some implementations, when the no-load voltage of the battery pack is about 18 volts, the target voltage may be set to about 13.5 volts.

[0090] FIG. 12 is a block diagram illustrating a feedback loop that may be used to implement a control scheme according to process 900 of FIGS. 9A-9B, process 1000 of FIGS. 10A-10B, and / or process 1100 shown in FIG. 11. As shown in FIG. 12, controller 400 may be configured to calculate a target voltage (such as a threshold value described above with reference to processes 900 and / or 1000). The target voltage is provided to a proportional integral control loop (which may be implemented by controller 400). Hardware (such as controller 400) generates and provides a control signal (such as a PWM signal) to motor 405. The hardware measures the voltage of the battery pack as it drives motor 405 in response to the control signal and provides the measured voltage as feedback to the PI control loop. In response to the voltage feedback exceeding the target voltage, the hardware does not adjust the control signal. However, in response to the voltage feedback falling below the target voltage, the hardware updates the control signal (e.g., by reducing the duty cycle of the PWM signal).

[0091] Thus, the methods and systems described herein use the voltage drop of the battery pack to determine a characteristic of the battery pack and optimize the operation of a motor of a battery-powered device (e.g., a power tool) based on the determined characteristic. For example, as described above, the capacity of a battery pack may be based on various factors, and thus different battery packs may exhibit different responses to the same applied load. For example, FIG. 13 is a graph showing the voltage drop of a first battery pack in response to a load as a function of time, and FIG. 14 is a graph showing the voltage drop of a second battery pack (having a lower capacity than the first battery pack) in response to the same load as a function of time. As shown in FIGS. 13 and 14, a battery pack having a higher capacity (such as the first battery pack) may exhibit a lower voltage drop in response to a current load than a battery pack having a lower capacity (such as the second battery pack).

[0092] Thus, in some implementations, for example, during a longer operating cycle, the output voltage of the battery pack may begin to drop. In some scenarios, the output voltage of the battery pack may drop below a threshold voltage, and the process 900 and / or 1000 may reduce the operating parameters of the motor 405 in response. However, such a gradual drop in the output voltage of the battery pack over a longer operating cycle may not be indicative of the capacity of the battery pack. Thus, it may be undesirable to unnecessarily limit the operating parameters of the motor 405 in response to this gradual drop in the output voltage of the battery pack. Thus, in some implementations, the thresholds at which the controller 400 reduces the operating parameters of the motor 405 (e.g., the thresholds used in decision block 922 of process 900 and / or the thresholds used in decision block 1014 of process 1000) are dynamically updated. By dynamically updating the thresholds, the operating parameters of the motor 405 are not unnecessarily limited.

[0093] 16 shows graph 1602 illustrating the power output over time of a motor 405 controlled according to a technique implemented without dynamic threshold updates and graph 1604 illustrating the power output over time of a motor 405 controlled according to a technique implemented with a dynamic threshold update process. As illustrated by graph 1602, a control scheme implemented without a dynamic threshold update process may reduce an operating parameter (such as output power) of the motor 405 over a longer operating cycle. In contrast, as illustrated by graph 1604, a control scheme implemented with a dynamic threshold update process may maintain a consistent operating parameter (such as output power) of the motor 405 over a longer operating cycle.

[0094] In some embodiments, the dynamic threshold update process uses a state of charge (SoC) estimator algorithm that takes into account the pack voltage gradually decreasing as the tool is used. As mentioned above, this dynamic threshold update may be used for longer applications, such as when a user pulls the trigger once and then uses the tool for several minutes. When the motor is running, it is difficult to directly measure the pack voltage. Thus, the SoC estimator estimates the pack DCIR and the pack voltage, and uses this information to adjust the tool optimization processes 900 and 1000 described above, especially to avoid unnecessary power limiting during long applications (use of the device 300).

[0095] The SoC estimator uses the current difference (e.g., of inverter 451, which may be used to calculate the current difference of DC bus 452) and the voltage difference (e.g., of DC bus 452 output to inverter 451) during the operating cycle of device 300. These information are used to derive a DCIR (direct current internal resistance) for the battery pack, which can be added to the voltage to estimate where the resting voltage will be once the tool stops drawing power. In other words, the SoC estimator adjusts the target voltage / thresholds in processes 900 and 100 above to account for the depletion of the battery over time. In some embodiments, the DCIR may be calculated according to the following equation (5):

number

[0096] Battery pack quiescent voltage V rest can be calculated as a function of the calculated DCIR, where the calculated quiescent voltage V rest may represent an estimate of the quiescent voltage of the battery pack after the motor 405 stops pulling the load.

[0097] The controller 400 calculates the quiescent voltage V rest In various implementations, the controller 400 may use the techniques described above with reference to blocks 906 and / or 1006 to calculate the updated thresholds to use the calculated quiescent voltage V of the battery pack instead of the no-load voltage of the battery pack. rest is used.

[0098] FIG. 17 is a block diagram 1700 illustrating measurements and calculations that may be used to implement a control scheme according to the dynamic update threshold process described above. For example, a measured inverter duty cycle of inverter 451 and a measured inverter current of inverter 451 may be used to estimate a current value at DC bus 452. A DC bus voltage of DC bus 452 and an estimated current value of DCIR bus 452 may be used to estimate DCIR. An estimated current value at DC bus 452, an estimated DCIR, and a DC bus voltage may be used to estimate a quiescent voltage of the battery pack. The estimated quiescent voltage may be used by a voltage sag controller, which may be implemented by controller 400, to update a threshold voltage. Controller 400 may then use the updated threshold voltage to control motor 405. In some implementations, an estimated quiescent voltage of the battery pack may be used alternatively (by itself or with other data) as a voltage compared to a previously calculated threshold, which also avoids unnecessary power curtailment during long applications.

[0099] Accordingly, the embodiments described herein use thresholds (e.g., target voltages) that represent voltage drops or sags that distinguish battery packs having one capacity (or other characteristic) from battery packs having a different capacity (or other characteristic). As mentioned above, the thresholds may be set based on empirical data collected for devices and various battery packs in various operating applications and / or environments. For example, FIG. 15 is a graph illustrating the voltage of a battery pack as a function of load, showing regions (e.g., for certain load and pack voltage combinations) where the controller (hardware) generates an updated control signal (e.g., a reduced PWM signal to reduce an operating parameter of the motor 405) according to some embodiments described herein, and regions where the controller (hardware) does not generate an updated control signal. As mentioned above, in some implementations, multiple thresholds may be used to establish more than two different categories of battery packs. Each category may be associated with a different control signal for the motor 405 to optimize the operation of the motor for the category of battery pack connected to it. As also mentioned above, in some embodiments, the thresholds used by the systems and methods described herein may be further adjusted to take into account the operating application and / or environment of the battery-powered device and / or battery pack.

[0100] Thus, the embodiments described herein provide, among other things, systems and methods for controlling the operational sequence of a battery pack powering device. Various features and advantages are set forth in the following claims.

Claims

1. an interface configured to receive a battery pack; a sensing circuit configured to detect a voltage of the battery pack; an electronic controller; 1. A battery pack powering device, comprising: The electronic controller includes: receiving a first signal from the sensing circuit indicative of a no-load voltage of the battery pack; determining a threshold voltage based on the no-load voltage; generating a control signal for driving an electric motor of the battery pack powering device in response to activation of a trigger switch, the control signal driving the electric motor to operate at first operating parameters; receiving a second signal from the sensing circuit indicative of an output voltage of the battery pack during operation of the electric motor; updating the control signal in response to the second signal indicating that the output voltage is below the threshold voltage. It is configured as follows: the updated control signal drives the electric motor to operate at a second operating parameter, the second operating parameter being less than the first operating parameter. Battery pack powered device.

2. The battery pack powered device of claim 1 , wherein the threshold voltage is determined as a rate of decrease of a nominal input voltage of the battery pack powered device.

3. The battery pack powering device of claim 2 , wherein the reduction rate is approximately 25% reduction.

4. 2. The battery pack powering device of claim 1, wherein a nominal input voltage of the battery pack powering device is about 18 volts and the threshold voltage is about 13.5 volts.

5. the control signal includes a first pulse width modulated signal; the updated control signal includes a second pulse width modulated signal; a duty cycle of the first pulse width modulated signal is greater than a duty cycle of the second pulse width modulated signal; The battery pack powering device of claim 1 .

6. the first operating parameter is a first power output; the second operating parameter is a second power output; the first power output is greater than the second power output; The battery pack powering device of claim 1 .

7. the first operating parameter is a first torque output; the second operating parameter is a second torque output; the first torque output is greater than the second torque output; The battery pack powering device of claim 1 .

8. the first operating parameter is a first operating duration; the second operating parameter is a second operating duration; the first operation duration is greater than the second operation duration; The battery pack powering device of claim 1 .

9. An electric motor; an interface configured to receive a battery pack that powers the electric motor; a sensing circuit configured to detect a voltage of the battery pack; an electronic controller; 1. A battery pack powering device, comprising: The electronic controller includes: commencing a test current draw from the battery pack; receiving a first signal from the sensing circuit indicative of an output voltage of the battery pack during the test current draw; selecting a first control mode for controlling the electric motor in response to the first signal indicating that the output voltage is not below a threshold; selecting a second control mode for controlling the electric motor in response to the first signal indicating that the output voltage is below the threshold. It is configured as follows: the electronic controller is configured to generate a first control signal for controlling the electric motor in the first control mode; the electronic controller is configured to generate a second control signal for controlling the electric motor in the second control mode; the second control signal reduces an operating parameter of the electric motor relative to the first control signal. Battery pack powered device.

10. The battery pack powering device of claim 9 , wherein the threshold is determined as a rate of decrease of a designed output voltage of the battery pack.

11. The battery pack powering device of claim 10 , wherein the reduction rate is approximately a 25% reduction.

12. 10. The battery pack powering device of claim 9, wherein the designed output voltage of the battery pack is approximately 18 volts and the threshold is approximately 13.5 volts.

13. the first control signal is a pulse width modulated signal having a first duty cycle; the second control signal is a pulse width modulated signal having a second duty cycle; the first duty cycle is greater than the second duty cycle; 10. The battery pack powering device of claim 9.

14. the first control signal controls the electric motor to operate at a first power output; the second control signal controls the electric motor to operate at a second power output; the first power output is greater than the second power output; 10. The battery pack powering device of claim 9.

15. the first control signal controls the electric motor to operate at a first torque output; the second control signal controls the electric motor to operate at a second torque output; the first torque output is greater than the second torque output; 10. The battery pack powering device of claim 9.

16. the first control signal controls the electric motor to operate for a first duration; the second control signal controls the electric motor to operate for a second duration; the first duration is greater than the second duration; 10. The battery pack powering device of claim 9.

17. 1. A method of operating a battery pack powering device, comprising: In response to activation of the trigger switch, measuring, at a controller, a first voltage of a battery pack electrically connected to the battery pack powering device prior to application of a load associated with activation of the trigger switch; calculating, at the controller, a target voltage based on the first voltage; During application of the load associated with activation of the trigger switch, Measuring a second voltage of the battery pack; comparing the second voltage to the target voltage; and modifying operation of the battery pack powering device in response to the second voltage being less than the target voltage. method.

18. 20. The method of claim 17, wherein calculating the target voltage comprises decreasing the first voltage by a predetermined percentage.

19. The method of claim 17 , wherein modifying the operation of the battery pack powered device includes modifying a pulse width modulated control signal for an electric motor of the battery pack powered device.

20. The method of claim 17 , wherein modifying the operation of the battery pack powering device includes modifying the operation of the battery pack powering device using a proportional-integral control loop.

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