Determining voltage sag of battery pack to identify and control performance of battery pack

Abstract

An apparatus powered by a battery pack includes an interface configured to receive the battery pack, 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 from the sensing circuit indicative of an unloaded voltage of the battery pack, determine a threshold voltage based on the unloaded voltage, generate a control signal to drive the electric motor at a first operating parameter in response to activation of the trigger switch, receive a second signal from the sensing circuit, and drive the electric motor at a second operating parameter. And updating the control signal to drive the electric motor at a second operating parameter less than the first operating parameter in response to a second signal indicating that the output voltage is below the threshold voltage. The second signal is indicative of an output voltage of the battery pack during operation of the electric motor.

Description

[0001] This application claims the benefit of U.S. Provisional Application No. 63 / 584,773, filed on September 22, 2023. The entire disclosure of the above application is hereby incorporated by reference into this application. Technical Field

[0002] The present invention 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 a variety of technical and practical benefits. For example, a user may be able to easily swap battery packs between different tools without having to have a specific battery pack for each tool. If a battery pack fails or runs out of power, the battery pack can be quickly replaced with another battery pack (e.g., from a different tool). Having a common interface format also allows different battery packs from different tools to be charged on the same charger. These interoperability improvements greatly increase the flexibility of power tool systems. However, different battery packs may have different capabilities. These capability differences may be caused by design differences, or by the natural degradation of battery cell chemistry or performance over time.

[0004] For example, batteries of different capacities may have different internal resistances. Some higher capacity batteries may have lower internal resistances than some lower capacity batteries. Some higher capacity batteries may have more active materials in the electrodes, thicker electrodes, and / or electrodes with larger electrode surface areas, which can reduce the internal resistance of the battery. Higher capacity batteries may also have more cells arranged in parallel, which can also reduce the internal resistance of the battery. Higher capacity batteries may also use higher quality electrolyte solutions, which also help to reduce internal resistance. As a function of their lower internal resistance, higher capacity batteries may exhibit a lower voltage drop (also called voltage sag) than lower capacity batteries in response to the same current consumption demand.

[0005] The voltage drop V The current consumption can be expressed according to Ohm's law as I and the internal resistance of the battery pack R The function is shown in the following equation (1):

[0006] As shown in equation (1), in response to the current consumption I The voltage drop of the battery pack V Can be used as internal resistance R Thus, as described herein, a power tool (e.g., an electronic controller included in the tool) is configured to use a battery pack to respond to a given load (such as currentI ) and the voltage drop V To determine the capacity of the battery pack and optimize the control signal of the power tool based on the capacity of the battery pack.

[0007] Techniques that use voltage drop to determine battery capacity, such as those described in this patent specification, can provide advantages over techniques that measure other properties, such as impedance, particularly at colder temperatures. For example, the impedance of a battery includes and / or is a function of both a resistive component (e.g., resistance) and a reactive component (e.g., chemical reactions within the battery). Because chemical reactions within the battery may tend to slow down at colder temperatures, the impedance of a battery cell tends to increase more than the impedance at colder temperatures. Because the voltage drop of a battery can be a function of the resistance of the battery, voltage drop-based techniques, such as those described in this patent specification, provide a more accurate assessment of battery capacity at colder temperatures than other impedance-based techniques.

[0008] According to some examples, a battery-powered device (such as, for example, 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 from the sensing circuit indicating a no-load voltage of the battery pack, determine a threshold voltage based on the no-load 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 indicating that the output voltage is lower than the threshold voltage. The second signal indicates the 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 reduction of the nominal input voltage of the device powered by the battery pack. In some aspects, the percentage reduction is a reduction of about 25%. In some aspects, the nominal input voltage of the device powered by the battery pack 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, the updated control signal includes a second pulse width modulated signal, and the duty cycle of the first pulse width modulated signal is greater than the duty cycle of the second pulse width modulated signal.

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

[0011] Other embodiments provide a battery-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 less than 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 less than the threshold. The battery pack powers the electric motor. The first signal indicates 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 aspects, the threshold value is determined as a percentage reduction of the designed output voltage of the battery pack. In some aspects, the percentage reduction is a reduction of about 25%. In some aspects, the designed output voltage of the battery pack is about 18 volts and the threshold value is about 13.5 volts. In some aspects, the first control signal is a pulse width modulated signal with a first duty cycle, the second control signal is a pulse width modulated signal with a second duty cycle, and the first duty cycle is 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, the second control signal controls the electric motor to operate at a second power output, and the first power output is greater than the second power output. In some aspects, 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, and the first torque output is greater than the second torque output. In some aspects, 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, and the first duration is longer than the second duration.

[0014] Some embodiments provide a method of operating a battery-powered device (e.g., a power tool) that includes, in response to activation of a trigger switch, determining, with a controller, a first voltage of a battery pack electrically connected to the device before applying 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 determining a second voltage of the battery pack, comparing the second voltage to the target voltage, and modifying operation of the battery-powered device in response to the second voltage being less than the target voltage.

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

[0016] Other embodiments, implementations, features, and aspects will become apparent from careful reading of the detailed description and accompanying drawings.

[0017] Before explaining any specific embodiment in detail, it should be understood that the specific embodiment is not limited to the application in the configuration details and component arrangements described in the following description or shown in the accompanying drawings. The specific embodiments can be implemented or realized in various ways. In addition, it should be understood that the words and terms used in this application are for illustrative purposes and should not be regarded as limiting. The use of "including", "comprising", "having" and their variations means that both the items listed thereafter and their equivalents and additional items are covered. Unless otherwise specified or limited, the terms "install", "connect", "support" and "couple" and their variations are used in a broad sense, covering both direct installation, connection, support and coupling, and indirect installation, connection, support and coupling.

[0018] The articles "a," "an," and "the" should not be construed as meaning "one" or "only one," unless the context clearly indicates otherwise. Instead, these articles should be construed as meaning "at least one" or "one or more than one." Similarly, when the term "the" or "said" is used to refer to a noun previously introduced by the indefinite article "a" or "an," "the" or "said" means "at least one" or "one or more than one," unless the context clearly indicates otherwise.

[0019] In addition, it should be understood that a specific embodiment may include hardware, software, and electronic components or modules, and for the purpose of discussion, these hardware, software, and electronic components or modules may be shown and described as if most of the components are implemented only in hardware. However, based on the reading of the specific embodiments of the present application, a person of ordinary skill in the art will recognize that in at least one specific embodiment, the electronic-based aspects can be implemented in software (e.g., stored on a non-transitory computer-readable medium), and the software 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 a plurality of hardware- and software-based devices and a plurality of different structural components can be used to implement specific embodiments. For example, the "server", "computing device", "controller", and "processor" described in this specification may include one or more processing units, one or more computer-readable medium modules, one or more input / output interfaces, and various connectors (e.g., system buses) connecting these components.

[0020] For relative terms used in relation to quantities or conditions, such as "about", "approximately", "substantially", etc., those of ordinary skill in the art will understand that the values ​​are included, and the meaning of the terms is determined by the context (for example, the terms include at least the degree of error associated with the precision of the measurement, the tolerance associated with the specific value [for example, manufacturing, assembly, use tolerance, etc.], etc.). Such terms should also be considered to disclose the range defined by the absolute values ​​of the two endpoints. For example, the expression "from about 2 to about 4" also discloses the range of "from 2 to 4". Relative terms can refer to positive and negative percentages (for example, 1%, 5%, 10%) of the indicated value.

[0021] It should be understood that although some drawings show hardware and software located in a particular device, these depictions are for illustrative purposes only. The functions performed by a component described in this application can be performed in a distributed manner by multiple components. Similarly, the functions performed by multiple components can be combined and performed by a single component. In some specific embodiments, the components shown can be combined or divided into separate software, firmware and / or hardware. For example, logic and processing can be distributed between multiple electronic processors, rather than being located in a single electronic processor and performed by a single electronic processor. Regardless of how they are combined or divided, hardware components and software components can be located in the same computing device, or can be distributed between different computing devices connected by one or more than one network or other suitable communication links. Similarly, the components that perform specific functions can also perform additional functions not described in this application. For example, a device or structure that is "configured" in a certain way is configured at least in this way, but can also be configured in a way that is not explicitly listed.

[0022] Accordingly, in the claims, if an apparatus, method or system is described as, for example, comprising a controller, a control unit, an electronic processor, a computing device, a logic element, a module, a memory module, a communication channel or network, or other elements configured in some manner to, for example, perform multiple functions, this claim or the elements of the claim should be interpreted as indicating one or more of such elements, such an element, i.e., any one of the one or more elements is configured as described in the claim to, for example, implement any one or more of the listed multiple functions, so that the one or more elements as a group together perform multiple functions. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A A battery pack according to some embodiments of the present invention is shown.

[0024] Figure 1B A group of battery cells according to some embodiments of the present invention is shown.

[0025] Figure 2A A battery pack according to some embodiments of the present invention is shown.

[0026] Figure 2B A group of battery cells according to some embodiments of the present invention is shown.

[0027] Figure 3 A method for determining a battery pack (such as Figure 1A or Figure 2A The impedance of the battery pack).

[0028] Figure 4 A control system of an apparatus according to some embodiments of the present invention is shown, for example Figure 3 device.

[0029] Figure 5 Some embodiments of the present invention are shown. Figure 4 A circuit diagram of a field effect transistor (FET) switch module of a device.

[0030] Figures 6A-6D A circuit for demonstrating some embodiments of the present invention (such as Figure 5 A circuit diagram showing the flow of current in a circuit.

[0031] Figure 7 Some embodiments of the present invention are shown in FIG. Figure 4 Block diagram of the power input module of the device.

[0032] Figure 8Some embodiments of the present invention are shown in FIG. Figure 7 Circuit diagram of the voltage divider circuit of the power input module.

[0033] Fig.9A , Fig. 9B , Fig. 10A and Fig. 10B FIG. 2 is a diagram showing a device for controlling battery power supply according to some embodiments of the present invention (such as Figure 3 A flowchart of a process of the operating sequence of the device).

[0034] Fig.11 A block diagram showing a process for implementing a control scheme according to some embodiments of the present invention is shown, as well as a graph showing the measured voltage of a battery pack as a function of time.

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

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

[0037] Fig.14 is a diagram showing an exemplary second battery pack (having a ratio Fig.13 A graph of the voltage drop as a function of time in response to the same current load for a first battery pack (lower capacity).

[0038] Fig.15 is a graph showing the voltage of a battery pack as a function of load and showing the region where the controller generates an updated control signal (at a target voltage) according to some embodiments of the present invention.

[0039] Fig.16 A graph showing power output of a motor of a battery powered device during an operation cycle implemented with a dynamic threshold update process and an operation cycle implemented without a dynamic threshold update process is shown.

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

[0041] Among the drawings, reference numerals may be repeated to identify similar and / or identical elements. DETAILED DESCRIPTION

[0042] Figure 1AA battery pack 100 is shown. The battery pack 100 includes a housing 105, an optional user interface portion 110 for providing an indication of the state of charge of the battery pack 100, and a device interface portion 115 for connecting the battery pack 100 (e.g., mechanically and electrically) to a device (e.g., a power tool). The battery pack 100 includes a plurality of battery cells within the housing 105.

[0043] Figure 1B A group 125 of battery cells 120 is shown that includes, for example, ten individual battery cells 120. The battery cells 120 can be located within a housing 105 of the battery pack 100. In some embodiments, the battery pack 100 includes more or less than 10 battery cells within the housing 105.

[0044] Figure 2A A battery pack 200 for powering a device (eg, a power tool) is shown. The battery pack 200 includes a battery housing 230 and a plurality of battery cells 290 (see Figure 2B ).

[0045] Figure 2B An interior view 245 of the battery housing 230 is shown. Figure 2B As shown, the battery housing 230 includes a wall 265 having an inner surface 280 and an outer surface 275. The inner surface 280 defines an inner cavity 270. The outer surface 275 includes a top surface portion 215 ( Figure 2A ) and bottom portion 285. Figure 2B , the battery cells 290 disposed in the cavity 270 are connected in series to the battery contacts 205. Figure 2A , multiple contacts 250( Figure 2B ) is disposed on a top surface portion 215 within the battery contact housing extension 210. The housing extension 210 is configured to engage with one or more power tools or power accessories. A battery charge indicator 220 may also be disposed on the housing ( Figure 2A ), and additional battery charging, monitoring and indication components 255 may be disposed within cavity 270 ( Figure 2B ).like Figure 2AAs shown, two tabs 235 are coupled to the housing 230 for releasably securing the housing 230 to the power tool. Features corresponding to those described above with respect to the battery pack 200 may also be included in the battery pack 100. It should be understood that the battery packs 100 and 200 are provided as exemplary illustrations of battery packs, and that 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). In addition, it should be understood that the battery packs used as part of the embodiments described herein may include additional or fewer components in various configurations, and that the battery packs 100 and 200 shown are not limiting.

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

[0047] Figure 4 A control system for the device 300 is shown. The control system includes a controller 400. The controller 400 is electrically connected and / or communicatively connected to various modules or components of the device 300. For example, the controller 400 is shown 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 switch module 450 (e.g., including a plurality of switch FETs). The controller 400 includes a combination of hardware and software that can be used, among other things, to control the operation of the device 300 (e.g., control the operation of the motor 405), monitor the operation of the device 300, activate one or more indicators 430 (e.g., LEDs), etc.

[0048] Controller 400 includes a plurality of electrical and electronic components that provide power, operational control, and protection to components and modules within controller 400 and / or device 300. For example, 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. Processing unit 455 includes, among other things, a control unit 475, an ALU 480, and a plurality of registers 485 (in Figure 4 4 (shown as a set of registers) and implemented using known computer architectures (e.g., modified Harvard architecture, von Neumann architecture, etc.). The processing unit 455, memory 460, input unit 465, and output unit 470, 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., common bus 490). For illustrative purposes, the Figure 4 The control and / or data busses are generally shown in FIG. In view of the described embodiments of the present invention, it will be known to those skilled in the art to use one or more control and / or data buses for interconnection and communication between various modules, circuits and components.

[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 may 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 that can be stored in the RAM of the memory 460 (e.g., during execution), the ROM of the memory 460 (e.g., on a substantially permanent basis) or another non-transitory computer-readable medium (such as another memory or disk). The 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 than one application, program data, filters, rules, one or more than one program modules and other executable instructions. The controller 400 is configured to retrieve and execute instructions particularly related to the control process and method described in the present invention from the memory 460. In other configurations, the controller 400 includes additional, fewer or different components.

[0050] The battery pack interface 410 includes a combination of mechanical components (e.g., rails, grooves, latches, etc.) and electrical components (e.g., one or more terminals) that are configured and can be used to dock (e.g., mechanically, electrically, and optionally communicatively connect) the device 300 with a battery pack (e.g., battery packs 100 and 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 received from the battery pack 100 before providing the power to the controller 400. The battery pack interface 410 also provides power to the FET switch module 450 to power the motor 405. The battery pack interface 410 may also include, for example, a communication line 495 for providing a communication link between the controller 400 and the battery pack 100.

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

[0052] The user input module 435 is operably coupled to the controller 400 to, for example, select a forward mode of operation or a reverse mode of operation, a torque and / or speed setting setting of the device 300 (e.g., using a torque and / or speed switch), or other operations 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 thereof, 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 aspects, the controller 400 is configured to determine whether a fault condition of the device 300 exists and to 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 the data received from the sensing circuit 425 (e.g., in raw form, processed form, or a combination thereof) with one or more predetermined operational thresholds or limits that the controller 400 can calculate or access (e.g., within the memory 460). For example, when the controller 400 detects or predicts a potential thermal fault (e.g., of a FET, motor 405, etc.), the controller 400 may be configured to limit or interrupt the power supplied from the interface battery pack to the motor 405 until, for example, the likelihood of a thermal fault decreases, the device 300 is reset, etc. In some aspects, the controller 400 is configured to provide information and / or control signals to another component of the device 300 (e.g., the indicator 430), the battery pack 100 or 200 (e.g., via the battery pack interface 410), or a combination thereof in response to detecting one or more such fault conditions of the device 300 or determining that the fault condition of the device 300 no longer exists. Fig.9A , Fig. 9B , Fig. 10A and Fig. 10B In more detail, in some aspects, in addition to or as an alternative to using sensing circuit 425 to detect a fault condition, controller 400 uses sensing circuit 425 to determine the capacity (eg, internal impedance) of a battery pack interfaced with device 300 .

[0054] In various implementations, the FET switch module 450 can be connected to or be part of an inverter 451 that provides alternating current (AC) power to the motor 405. For example, the battery pack interface 410 can be connected to a direct current (DC) bus 452, and the DC bus 452 can be connected to the inverter 451 and / or the FET switch module 450. The battery pack interface 410 can provide DC power to the DC bus 452. The DC bus 452 can provide DC power to the inverter 451. The inverter 451 can include a switching device, such as the FET switch module 450, and control the switching device to create an AC waveform from the source DC power. The inverter 451 can provide the AC waveform as AC power to drive the motor 405. As shown in FIG. Figure 4 As shown, in some embodiments, 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] Figure 5 A circuit diagram 500 of the FET switch module 450 is shown. The FET switch module 450 includes a plurality of high-side power switch elements 502 and a plurality of low-side power switch elements 504. In some aspects, the controller 400 provides control signals to control the high-side FET 502 and the low-side FET 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), thereby causing power from a power source 510 (e.g., one of the battery packs 100 and 200 docked with the device 300) to be selectively applied to the stator coils 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 time period. In response to determining that the rotor of the motor 405 has rotated based on the pulses from the sensing 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 the pulses from the sensing 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 cycle of enabling the paired high-side FET 502 and low-side FET 504 is repeated in sequence to drive the motor 405. In addition, in some embodiments, the control signal includes a pulse width modulation (PWM) signal having a duty cycle set in proportion to the trigger pull amount of the trigger 420 to thereby control the speed or torque of the motor 405. It should be understood that the device 300 can include different configurations for controlling power from the power supply 510 to the motor 405, and the FET 504 and associated components are provided as non-limiting examples.

[0056] For example, Fig. 6A A current flow diagram 600 of the FET switch module 450 is shown. As described above, the FET switch module 450 includes a plurality of high-side power switch elements 502 and a plurality of low-side power switch elements 504. 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 FETs 502 and 504 (e.g., sequentially, in pairs), thereby causing power to be provided from the power source 510 (e.g., the battery pack 100, 200). The current 610 travels from the power source 510 through one of the high-side power switch elements 502 to the stator coil of the motor 405. The current 610 then travels from the motor 405 to one of the low-side power switch elements 504 before completing the connection path 615 of the power source 510.

[0057] Figure 6B Another current flow diagram 620 of the FET switch module 450 is shown. As described above, the FET switch module 450 includes a plurality of high-side power switch elements 502 and a plurality of low-side power switch elements 504. 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 FETs 502 and 504 (e.g., sequentially, in pairs), thereby causing power to be provided from the power source 510 (e.g., the battery pack 100, 200). The current 610 travels from the power source 510 through a high-side power switch element 502 to a low-side power switch element 504. The current 610 then closes the circuit by returning to the power source 510. The reduced current 610 path only travels through the two switching FETs and completes the shorter portion of the path of the connection 615 of the power source 510. In some aspects, one or more high-side power switch elements 502 and / or one or more low-side power switch elements 504 are enabled at the same time. Such control may reduce the overall resistance of the system and enable higher current to flow through FETs 502 and 504 and distribute the load of the system through FETs 502 and 504 to reduce FET 502 and 504 burn-up.

[0058] Figure 6C Another current flow diagram 625 of the FET switch module 450 is also shown. In this example, an additional switch module 630 is connected to the connection path 615. In addition to the additional switch module 630, an additional resistor is also connected to the path of the connection 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 switch module 630, thereby causing power to be provided from the power source 510 (e.g., the battery pack 100, 200). The current 610 travels from the power source 510 through the additional resistor and then through the additional switch module 630. In this embodiment, the current 610 only travels through the additional resistor and the additional switch module 630 before returning to the power source 510 to close the circuit. In other aspects, an inductor can be used for similar purposes as the additional resistor. In addition, other circuit configurations can be configured in a manner that other components (e.g., capacitors) can be used.

[0059] Fig.6DYet another current flow diagram 635 of the FET switch module 450 is shown. In this embodiment, only one power switch 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 switch element 504, thereby causing power to be provided from the power source 510 (e.g., the battery pack 100, 200). The current 610 travels from the power source 510 to the motor 405 (e.g., a brushed motor) and the power switch element 504 before closing the path of the connection 615.

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

[0061] Figure 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 input of the voltage divider circuit 702 can be coupled to the positive terminal and the negative terminal of the battery pack interface 410. The voltage divider circuit 702 can step down the output voltage of a battery pack (such as the battery pack 100 or the battery pack 200) connected to the battery pack interface 410, and output the stepped-down voltage to the analog-to-digital converter 704. The analog-to-digital converter 704 converts the analog stepped-down voltage signal into a digital signal and outputs the digital signal to the controller 400. As described with respect to Figure 8 In more detail, 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 embodiment where 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 the stepped-down voltage output from the voltage divider circuit 702 to the analog-to-digital converter 704 according to a voltage divider equation suitable for the voltage divider circuit 702.

[0062] Figure 8 is a circuit diagram showing a voltage divider circuit 702 according to some embodiments. Figure 8 As shown, some embodiments 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 can be connected to a first node between the first resistor 806 and the second resistor 808, and a second output terminal 812 can be connected to a second node between the second input terminal 804 and the second resistor 808. In some embodiments, the battery pack (composed of Figure 8The battery 814 in FIG. 1 , which may include the battery pack 100 or 200 described in the present invention, 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, an input voltage from the battery 814 may be applied across the first resistor 806 and the second resistor 808. V in Because the first resistor 806 and the second resistor 808 can be connected in series, the resistance of the first resistor 806 can be R 1 and the resistance of the second resistor 808 R 2 Divide the input voltage between the first resistor 806 and the second resistor 808 V in .

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

[0064] The relationship between the resistors in the voltage divider equation (2) above can be expressed as the transfer function H , as shown in the following equation (3):

[0065] Therefore, as regards Figure 8 In more detail, the controller 400 may be based on the voltage output from the voltage divider circuit 702 (with V out The voltage of the battery 814 is calculated (expressed as V in express):

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

[0067] Figures 9A-9Bis a flow chart of a process 900 for controlling an operational sequence of device 300 according to some embodiments, and specifically illustrates a process for determining a characteristic (e.g., capacity, impedance, etc.) of a battery pack electrically connected to device 300 based on a measured voltage and using the determined characteristic to generate one or more control signals for controlling motor 405. Although the operation of process 900 is described in conjunction with a specific embodiment described herein, process 900 may be implemented in any suitable setting. Figures 9A-9B In the embodiment, each operation is shown once in a specific order, but the operation can be reordered and / or repeated as needed and appropriate. For example, different operations can be appropriately performed in parallel. In various embodiments, a battery pack with a higher capacity can exhibit a lower (smaller) voltage drop in response to a given current consumption compared to a battery pack with a lower capacity. Therefore, the voltage drop of the battery pack in response to a given current consumption can be used to determine the capacity of the battery pack connected to the device 300, and the controller 400 can 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 can control the motor 405 to operate at a higher operating parameter. Conversely, in response to determining that the battery pack is a lower capacity battery pack, the controller 400 can control the motor 405 to operate at a lower operating parameter. In various embodiments, the operating parameter can be the speed of the motor 405. In some embodiments, the operating parameter can be the power output of the motor 405 (e.g., torque output τ multiplied by angular velocity ω). In some embodiments, the operating parameter can be the torque output of the motor 405. In various embodiments, the operating parameter can be the running time (operation duration) of the motor.

[0068] At box 902, the controller 400 determines 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, when there is no current load (or a minimum current load) on the battery pack, the voltage divider circuit 702 can reduce the no-load voltage of the battery pack obtained across the positive terminal and the negative terminal of the battery pack at the battery pack interface 410. The analog-to-digital converter 704 can convert the analog no-load voltage of the battery pack into a digital no-load voltage signal and output the digital no-load voltage signal to the controller 400. At box 904, the controller 400 determines the no-load voltage of the battery pack based on the digital no-load voltage signal. In various embodiments, 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 into the no-load voltage of the battery pack according to the transfer function of the voltage divider circuit 702 (for example, as previously described in conjunction with the description of FIG. 1 ). Figure 7 and Figure 8 described above).

[0069] At box 906, the controller 400 determines a threshold value based on the no-load voltage of the battery pack. In various embodiments, 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 a target voltage may be defined, wherein a measured voltage drop above the target voltage indicates a high-capacity battery pack, and a measured voltage drop equal to or lower than the target voltage indicates a low-capacity battery pack. In various embodiments, the threshold value may be set to a value of about 15%, 20%, 25%, 30%, 35%, or 40% (or any other value between about 15% and about 40%). However, in some embodiments, the threshold value 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, the controller 400 may be pre-programmed with a threshold value, rather than calculating the threshold value from a measured value, which may be stored and associated with the threshold value (e.g., via a lookup table or other data structure or data mapping mechanism). Thus, after determining the no-load voltage, the controller 400 may determine the threshold value by retrieving the appropriate threshold value from a memory. In addition, in some embodiments, the controller 400 may determine the no-load voltage of the battery pack based on other values, such as data transmitted between the device 300 and a connected battery pack, a stored voltage setting of the device 300, or a combination thereof. For example, the threshold value 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 approximately 18 volts, the threshold value may be set according to Table 1 below:

[0070] Although the controller 400 may be configured to determine the threshold value without determining the no-load voltage of the battery pack, determining this voltage may allow the controller 400 to set the appropriate threshold value based on the current state of the battery pack.

[0071] In various embodiments, the threshold value, the percentage reduction relative to the nominal voltage, and / or the percentage reduction relative to the no-load voltage can be set based on empirical data for a particular type of device and one or more loads (or load ranges). In some embodiments, the empirical data can include different operating applications or environments of the device 300, which can be used to establish a tuned threshold value. The controller 400 can also be configured to tune (e.g., increase or decrease) the threshold value 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 for activation of the trigger switch 415. It should be appreciated that although the process 900 illustrates that the threshold is set prior to activation of the trigger switch 415 (e.g., as part of an initialization or configuration process of the device 300), in some implementations (see, e.g., Fig.12 902-906) may occur after the trigger switch 415 is activated but before the load is applied to the battery pack associated with the trigger activation. Determining the no-load voltage close to the time the load is applied may result in better optimization of the battery pack because a more accurate threshold value may be set based on the current state of the battery pack.

[0073] As previously described, the trigger switch 415 can be connected to the trigger 420, and the trigger 420 can actuate the trigger switch 415. In various embodiments, the trigger switch 415 can include an on-off switch, and the actuation of the trigger 420 closes the on-off switch. In some embodiments, the trigger switch 415 can include a variable resistor, such as a potentiometer. The variable resistor can 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 embodiments, the trigger switch 415 can include a Hall effect sensor. The Hall effect sensor can 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 can 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 determining that the trigger switch 415 has not been activated ("No" at decision block 910), the controller 400 continues to monitor activation of the trigger switch 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 embodiments, the control signal can be an analog signal, such as a voltage signal (e.g., a continuous signal in which changes in voltage can be used to control a parameter of the motor 405) or a current signal (e.g., a continuous signal in which changes in current can be used to control a parameter of the motor 405). In some embodiments, the control signal can be a digital signal, such as a pulse width modulated (PWM) signal. In embodiments where the control signal is a PWM signal, the duty cycle (e.g., the ratio of the on time to the total period of the signal) can be modulated to control the 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 box 916, the controller 400 uses the generated control signal to control the motor 405. For example, in an embodiment where the control signal is a PWM signal, the controller 400 can provide the control signal to the FET switch module 450, and the FET switch module 450 can drive the motor 405 based on the control signal, which applies a load to the battery pack electrically connected to the device 300. At box 918, the controller 400 monitors the output voltage of the battery pack (such as battery pack 100 or 200) connected to the battery pack interface 410 when the load is applied. For example, the controller 400 monitors the digital signal output from the analog-to-digital converter 704. At box 918, the controller 400 determines the output voltage of the battery pack connected to the battery pack interface 410. For example, the controller 400 determines the output voltage of the battery pack connected to the battery pack interface 410 based on the previous combination Figure 7 and Figure 8 The illustrated technique calculates the output voltage of the battery pack based on the digital signal output from the analog-to-digital converter 704 .

[0076] At decision block 922, the controller 400 determines whether the battery pack output voltage is less than a threshold value. As described herein, in various embodiments, the threshold value may be determined dynamically by the controller 400 (e.g., according to the process previously described in conjunction with blocks 902-906). In other embodiments, the controller 400 may be pre-programmed with the threshold value (e.g., as previously discussed in conjunction with process 900 and / or Table 1). In response to determining that the battery pack output voltage is not less than the threshold value ("No" at decision block 922), the controller 400 continues to monitor the output voltage of the battery pack at block 924 (e.g., by monitoring the digital signal output from the analog-to-digital converter 704), and the process 900 returns to block 920. In response to determining that the battery pack output voltage is less than 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 at block 914. In various embodiments, the control signal may be an analog control signal for driving the motor 405, and the updated control signal generated at block 926 may have a reduced voltage, current, and / or duration compared to the control signal generated at block 914. In some embodiments, the control signal may be a PWM control signal provided to the FET switch module 450, and the updated control signal generated at block 926 may have a reduced duty cycle compared to the control signal generated at block 914. In some embodiments, the controller 400 may reduce the duration of providing the control signal to the motor 405. At block 928, the controller 400 provides the updated control signal to the motor 405 (e.g., via the FET switch module 450). From block 928, the process 900 proceeds to block 924.

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

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

[0079] According to process 900 and Figures 9A-9B The implemented control scheme provides various technical benefits for battery-powered devices. For example, the controller 400 can dynamically determine the characteristics of the battery pack connected to the device 300 (such as capacity, impedance, etc.), and dynamically adjust the control signal used to control the motor 405, thereby optimizing the operating parameters of the motor 405 (such as speed, power, torque and / or run time) based on the characteristics of the battery pack, which can improve the performance of the battery pack and / or the device 300. For example, the controller 400 can detect when one or more operating parameters of the electric motor 405 exceed the optimal performance envelope of the battery pack (e.g., by causing an excessive voltage drop at the battery pack), and generate updated operating parameters to keep the operation of the electric motor 405 within the optimal performance envelope of the battery pack.

[0080] Figures 10A-10B 1 is a flow chart of a process 1000 for controlling an operational sequence of device 300 according to some embodiments, and specifically illustrates determining a characteristic (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 characteristic to generate one or more control signals for controlling motor 405. Although the operation of process 1000 is illustrated in conjunction with a specific embodiment described herein, process 1000 may be implemented in any suitable setting. Figures 10A-10B , each operation is shown once in a particular order, but operations may be reordered and / or repeated as appropriate as needed. For example, different operations may be performed in parallel as appropriate. In various embodiments, while the previously described process 900 monitors the battery pack as the battery pack 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 operating mode optimized for the battery pack (e.g., based on determined characteristics of the battery pack). The selected operating mode may thereafter be applied (e.g., when a trigger is activated) without, for example, determining and monitoring a voltage drop that occurs after the trigger is activated.

[0081] like Fig. 10AAs shown, at block 1002, the controller 400 determines 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 determines the no-load voltage signal, as previously described in connection with block 902. At block 1004, the controller 400 determines a no-load voltage of the battery pack based on the no-load voltage signal (e.g., as previously described in connection with block 904). At block 1006, the controller 400 determines a threshold value based on the no-load voltage of the battery pack (e.g., as previously described in connection with block 906). In various embodiments, the controller 400 may be pre-programmed with a threshold value (such as previously described in connection with processes 900 and 904). Figures 9A-9B described).

[0082] At block 1008, the controller 400 initiates a test current draw from a battery pack (such as battery pack 100 or 200) connected to the battery pack interface 410. 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 determines the output voltage of the battery pack according to the previously described method in conjunction with the analog-to-digital converter 704. Figure 7 and Figure 8 The described technique calculates the output voltage of the battery pack based on the digital signal output from the analog-to-digital converter 704. 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 embodiments, the threshold value may be any threshold value previously described in conjunction with decision block 922 of process 900. In response to determining that the output voltage of the battery pack is not less than 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 determining that the output voltage of the battery pack is less than 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] At box 1018, after selecting the operating mode, the controller 400 monitors whether the trigger switch 415 is activated. At decision box 1022, the controller 400 determines whether the trigger switch 415 has been activated. In response to determining that the trigger switch has not been activated ("No" at decision box 1022), the controller 400 continues to monitor the trigger switch 415 at box 1024, and the process 1000 proceeds back to decision box 1022. In response to determining that the trigger switch has been activated ("Yes" at decision box 1022), the controller 400 generates a control signal for the motor according to the selected control mode (at box 1026). In response to having selected the first control mode, the controller 400 generates a control signal that controls the motor 405 at a baseline operating parameter (such as, for example, a baseline speed, power, torque, and / or run time). In response to having selected the second mode, the controller 400 generates an updated or modified control signal that controls the motor 405 at a reduced operating parameter relative to the baseline operating parameter.

[0084] In various embodiments, the baseline operating parameter may include a first speed, and the reduced operating parameter may include a second speed less than the first speed. In some embodiments, the baseline operating parameter may include a first power, and the reduced operating parameter may include a second power 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 less than the first torque. In various embodiments, the baseline operating parameter may include a first operating time, and the reduced operating parameter may include a second operating time having a duration less than the first operating time. At box 1028, the controller 400 provides a control signal to the motor 405 (e.g., via the FET switch 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 motor 405. When more than two control modes are used, two or more thresholds (e.g., different thresholds for identifying 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 each time the device 300 is powered on or reset, after a predetermined time period, or a combination thereof.

[0087] Thus, similar to process 900, the control scheme implemented according to process 1000 provides various technical benefits for a battery-powered device. In addition, using the test current draw allows the control mode to be initially set for the device 300, which can simplify motor control after trigger activation (e.g., by reducing the need for voltage determination and monitoring compared to process 900).

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

[0089] In addition, as regards Fig.9A and Fig. 9B As described, in some embodiments, the threshold is determined in response to activation of a device trigger rather than as part of an initialization process or configuration process of the device 300. For example, Fig.11 is shown for use according to Figures 9A-9B Process 900 and / or Figures 10A-10B A block diagram of a process 1100 for implementing the control scheme of process 1000 and a graph 1105 showing the measured voltage of the battery pack as a function of time. Fig.11 As shown, hardware (such as controller 400) can measure the voltage of the battery pack at the state of charge ("SoC voltage") in response to detecting the activation (e.g., pulling) of trigger 420 but before applying the load otherwise associated with the trigger activation. For example, the SoC voltage can be as previously described in conjunction with process 900 and Figures 9A-9B and / or process 1000 and Figures 10A-10BThe hardware may calculate the target voltage based on the SoC voltage. For example, as previously described, the target voltage may be a threshold value, and as previously described in conjunction with process 900 and Figures 9A-9B and / or process 1000 and Figures 10A-10B After calculating the target voltage, the hardware uses the target voltage to adjust device (e.g., tool) operation (such as, operating parameters of motor 405 as described with respect to processes 900 and 1000). As shown in graph 1105, when the measured voltage of the battery pack is higher than the target voltage, the hardware can control motor 405 to operate at a first operating parameter, and when the measured voltage of the battery pack is lower than the target voltage, to operate at a second operating parameter less than the first operating parameter. For example, in some embodiments, when the no-load voltage of the battery pack is about 18 volts, the target voltage can be set to about 13.5 volts.

[0090] Fig.12 is shown to be applicable to implementation according to Figures 9A-9B The process of 900 Figures 10A-10B Course 1000 and / or Fig.11 A block diagram of the feedback loop of the control scheme of the process 1100 shown in FIG. Fig.12 As shown, the controller 400 can be configured to calculate a target voltage (such as the threshold value previously described in conjunction with the process 900 and / or 1000). The target voltage is provided to a proportional integral (PI) control loop (which can be implemented by the controller 400). Hardware (such as the controller 400) generates a control signal (such as a PWM signal) and provides it to the motor 405. As the battery pack drives the motor 405 in response to the control signal, the hardware measures the voltage of the battery pack and provides the measured voltage as feedback to the PI control loop. In response to the voltage feedback being higher than the target voltage, the hardware does not adjust the control signal. However, in response to the voltage feedback being lower than the target voltage, the hardware updates the control signal (such as by reducing the duty cycle of the PWM signal).

[0091] Thus, the methods and systems described herein use the voltage drop of a battery pack to determine a characteristic of the battery pack and use the characteristic to 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 can be based on various factors, and thus, different battery packs can exhibit different responses to the same applied load. For example, Fig.13 is a graph showing the voltage drop of the first battery group 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) as a function of time in response to the same load. Fig.13 and 14As shown, a battery pack having a higher capacity (eg, a first battery pack) may exhibit a lower voltage drop in response to a current load than a battery pack having a lower capacity (eg, a second battery pack).

[0092] In some embodiments, for example, during a longer operating cycle, the output voltage of the battery pack may begin to decrease. In some scenarios, the output voltage of the battery pack may decrease below a threshold voltage, and processes 900 and / or 1000 may reduce the operating parameters of the motor 405 in response. However, this gradual decrease in the output voltage of the battery pack over a longer operating cycle may not indicate the capacity of the battery pack. Therefore, it may not be desirable to unnecessarily limit the operating parameters of the motor 405 in response to this gradual decrease in the output voltage of the battery pack. Therefore, in some embodiments, the threshold value (e.g., the threshold value used at decision block 922 of process 900 and / or the threshold value used at decision block 1014 of process 1000) at which the controller 400 reduces the operating parameters of the motor 405 is dynamically updated. By dynamically updating the threshold value, the operating parameters of the motor 405 are not unnecessarily restricted.

[0093] For example, Fig.16 1602 and 1604 are shown, with 1602 showing the power output of the motor 405 controlled according to the technique implemented without the dynamic threshold update and 1604 showing the power output of the motor 405 controlled according to the technique implemented with the dynamic threshold update process over time. As shown in 1602, the control scheme implemented without the dynamic threshold update process can reduce the operating parameters (such as output power) of the motor 405 over a longer operating period. In contrast, as shown in 1604, the control scheme implemented with the dynamic threshold update process can maintain a consistent operating parameter (such as output power) of the motor 405 over a longer operating period.

[0094] In some embodiments, the dynamic threshold update process uses a state of charge (SoC) estimator algorithm that takes into account the slowly decreasing battery pack voltage as the tool is used. As described above, this dynamic threshold update can be used for longer applications, such as when the 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 battery pack voltage. Therefore, the SoC estimator estimates the battery pack's DCIR and the voltage of the battery pack, and use this information to adjust the tool optimization processes 900 and 1000 described above, and specifically avoid unnecessary power limitations during long-term applications (use of the device 300).

[0095] The SoC estimator uses the current differential (e.g., the current differential of the inverter 451, which can be used to calculate the current differential of the DC bus 452) and the voltage differential (e.g., the voltage differential of the DC bus 452 output to the inverter 451) during the operation cycle of the device 300. This information is used to derive the battery pack DCIR (DC internal resistance), which can be added back to the voltage to estimate where the resting voltage will be once the tool stops consuming power. In other words, the SoC estimator adjusts the target voltage / threshold in the above processes 900 and 100 to handle battery depletion over time. In some embodiments, it can be calculated according to the following equation (5): DCIR :

[0096] The resting voltage of the battery pack can be V rest As calculated DCIR The function is used to calculate the static voltage V rest may represent an estimate of the resting voltage of the battery pack after the motor 405 stops consuming the load.

[0097] The controller 400 may use the calculated quiescent voltage V rest To update the threshold value (e.g., the threshold value used at decision block 922 and / or decision block 1014). In various embodiments, the controller 400 calculates the updated threshold value using the techniques previously described in conjunction with blocks 906 and / or 1006, using the calculated resting voltage of the battery pack. V rest The no-load voltage of the substitute battery pack.

[0098] Fig.17 1700 is a block diagram illustrating measurements and calculations that may be used to implement a control scheme according to the dynamically updated 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 DC bus 452 may be used to estimate DCIR The estimated current value at the DC bus 452, the estimated DCIRThe DC bus voltage can be used to estimate the resting voltage of the battery pack. The estimated resting voltage can be used by the voltage sag controller, which can be implemented by the controller 400, to update the threshold voltage. The controller 400 can then use the updated threshold voltage to control the motor 405. In some embodiments, the estimated resting voltage of the battery pack can be used alternatively (alone or with other data) as a voltage compared to a previously calculated threshold value, which similarly avoids unnecessary power reduction during long-term applications.

[0099] Thus, embodiments of the present invention use thresholds (e.g., target voltages) that represent voltage drops or sags that distinguish a battery pack having one capacity (or other characteristic) from a battery pack having a different capacity (or other characteristic). As described above, the thresholds can be set based on empirical data collected for devices and different battery packs in various operating applications and / or environments. For example, Fig.15 405 ) and shows regions (e.g., specific load and battery pack voltage combinations) where the controller (hardware) generates updated control signals (e.g., such as reduced PWM signals to reduce operating parameters of motor 405) according to some embodiments described herein and regions where the controller (hardware) does not generate updated control signals. As previously described, in some embodiments, 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 motor 405 to optimize the operation of the motor for the category of connected battery pack. Also as previously described, in some embodiments, the thresholds used by the systems and methods described herein may be further tuned 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 sequence of operations of devices powered by a battery pack.Various features and advantages are set forth in the following claims.

Claims

1. Devices powered by batteries, including: 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 being configured to: receiving a first signal from the sensing circuit indicative of an unloaded 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 device in response to activation of a trigger switch, wherein the control signal drives the electric motor to operate at a first operating parameter, receiving a second signal from the sensing circuit, the second signal indicating an output voltage of the battery pack during operation of the electric motor, and The control signal is updated in response to the second signal indicating that the output voltage is below the threshold voltage, wherein the updated control signal drives the electric motor to operate at a second operating parameter, wherein the second operating parameter is less than the first operating parameter.

2. The battery-powered device of claim 1, wherein: The threshold voltage is determined as a percentage reduction of a nominal input voltage of the device powered by the battery pack.

3. The battery-powered device of claim 2, wherein the percentage reduction is a reduction of about 25%.

4. The battery-powered device of claim 1, wherein: The nominal input voltage of the device powered by the battery pack is about 18 volts, and the threshold voltage is about 13.5 volts.

5. The battery-powered device of claim 1, wherein: The control signal comprises a first pulse width modulation signal; The updated control signal comprises a second pulse width modulation signal; and The duty cycle of the first pulse width modulation signal is greater than the duty cycle of the second pulse width modulation signal.

6. The battery-powered device of claim 1, wherein: The first operating parameter is a first power output; The second operating parameter is a second power output; and The first power output is greater than the second power output.

7. The battery-powered device of claim 1, wherein: The first operating parameter is a first torque output; The second operating parameter is a second torque output; and The first torque output is greater than the second torque output.

8. The battery-powered device of claim 1, wherein: The first operation parameter is a first operation duration; The second operating parameter is a second operating duration; and The first operation duration is greater than the second operation duration.

9. Battery-powered devices, including: Electric motor; an interface configured to receive a battery pack, the battery pack powering the electric motor; a sensing circuit configured to detect a voltage of the battery pack; and An electronic controller, the electronic controller being configured to: Initiate a test current draw from the battery pack, receiving a first signal from the sensing circuit, the first signal indicating an output voltage of the battery pack during the test current drain, 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, and selecting a second control mode for controlling the electric motor in response to a first signal indicating that the output voltage is below the threshold; wherein the electronic controller is configured to generate a first control signal for controlling the electric motor in the first control mode; and The electronic controller is configured to generate a second control signal for controlling the electric motor in the second control mode, wherein the second control signal reduces an operating parameter of the electric motor compared to the first control signal.

10. The battery-powered device of claim 9, wherein: The threshold is determined as a percentage of reduction in a designed output voltage of the battery pack.

11. The battery-powered device of claim 10, wherein the percentage reduction is a reduction of about 25%.

12. The battery-powered device of claim 9, wherein the battery is designed to have an output voltage of approximately 18 volts, and the threshold is approximately 13.5 volts.

13. The battery-powered device of claim 9, wherein: The first control signal is a pulse width modulation signal having a first duty cycle; The second control signal is a pulse width modulation signal having a second duty cycle; and The first duty cycle is greater than the second duty cycle.

14. The battery-powered device of claim 9, wherein: 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; and The first power output is greater than the second power output.

15. The battery-powered device of claim 9, wherein: The first control signal controls the electric motor to operate with a first torque output; The second control signal controls the electric motor to operate with a second torque output; and The first torque output is greater than the second torque output.

16. The battery-powered device of claim 9, wherein: 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; and The first duration is longer than the second duration.

17. A method of operating a device powered by a battery pack, the method comprising: In response to activation of the trigger switch: determining, with a controller, a first voltage of a battery pack electrically connected to the device prior to applying a load associated with activation of the trigger switch, calculating, using the controller, a target voltage based on the first voltage, and During application of the load associated with activation of the trigger switch: determining a second voltage of the battery pack, comparing the second voltage to the target voltage, and Operation of the device powered by the battery is modified in response to the second voltage being less than the target voltage.

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

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

20. The method according to claim 17, wherein: Modifying the operation of the device powered by the battery pack includes modifying the operation of the device powered by the battery pack using a proportional-integral control loop.

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