System and method for dynamic motor field weakening in power plant vehicles

Abstract

Embodiments of the disclosure provide a system and a method for operating a motor control algorithm in a power tool to utilize dynamic field weakening. The method comprises operating the motor according to the dynamic field weakening, measuring sensor readings, and sampling the sensor readings. The method further comprises calculating an averaged sensor reading, comparing the averaged sensor reading with a predetermined sensor value, and continuing operation according to the dynamic field weakening if the averaged sensor reading has not exceeded the predetermined sensor value. The method further comprises changing the motor control algorithm to a static motor commutation sequence if the averaged sensor reading has exceeded the predetermined sensor value.

Description

background

[0001] Power tools, such as hydraulic tools, generate high forces to perform a wide variety of applications. In particular, high-force hydraulic crimping tools typically use a two-stage hydraulic pump design. Hydraulic crimping tools with two-stage pumps have significantly longer cycle times than tools with single-stage pumps because a two-stage pump compresses more oil, and the motor speed is determined by the torque or power required for the second stage of the two-stage cycle. Summary

[0002] An exemplary embodiment of the disclosure provides solutions to these problems by offering improved systems and methods for reducing the overall cycle time by providing feedback to the motor control unit. Some particular embodiments of the disclosure can be used to optimize the overall performance of single-stage pumps in hydraulic tools. In other embodiments, sensor feedback can be used to determine when a hydraulic cycle of a two-stage pump has transitioned from stage one to stage two. In some particular embodiments, the ability to increase the motor's idle speed in a first stage and then transition back to static commutation in a second stage reduces the overall cycle time, and these changes in motor power are advantageous for optimizing the overall tool performance.

[0003] Embodiments of the disclosure provide systems and methods for modifying a motor control algorithm in a power tool to utilize dynamic field weakening. The power tool comprises a motor, a stator, and a sensor. The method includes operating the motor according to dynamic field weakening by operating the motor above a rated speed by weakening a magnetic field of the stator. The method further comprises measuring sensor readings, sampling the sensor readings while the motor is running to generate sensor samples, and calculating an averaged sensor reading by averaging the sensor samples.The method further includes comparing the averaged sensor reading with a predetermined sensor value, continuing operation according to the dynamic field weakening if the averaged sensor reading has not exceeded the predetermined sensor value, and changing the motor control algorithm to a static motor commutation sequence if the averaged sensor reading has exceeded the predetermined sensor value. In some embodiments, the power tool is a hydraulic tool and the sensor is a pressure sensor. Brief description of the drawings Fig. Figure 1A shows an isometric view of a hydraulic tool according to an exemplary embodiment. Fig. Figure 1B shows an isometric view of an alternative hydraulic tool with a punch crimping head according to an exemplary embodiment. Fig. Figure 2 shows a block diagram of certain components of the system. Fig. 1 hydraulic tool shown. Fig. Figure 3 shows a flowchart of an example firmware algorithm procedure used in the hydraulic tool of the Fig. 1 is used. Detailed description

[0004] The following detailed description outlines various features and functions of the disclosed method with reference to the accompanying figures. The exemplary methods described here are not to be understood as limiting. It is self-evident that certain aspects of the disclosed method can be arranged and combined in a multitude of different configurations, all of which are considered here.

[0005] The disclosure generally relates to dynamic motor field weakening using a sensor. Dynamic field weakening is a motor control technique that allows the motor to operate at speeds above its rated speed by weakening the magnetic field in the motor's stator. By reducing the magnetic field strength, the back electromotive force (EMF) is reduced, enabling the motor to rotate at higher speeds. Field weakening reduces the strength of the gap field, thus lowering the back EMF at a given speed. The lower back EMF constant (torque constant) caused by field weakening allows the motor to run at a higher speed. Typically, this can double the available motor speed.

[0006] In embodiments of the disclosure, the sensor can be a pressure sensor, a distance sensor, a battery current sensor, a Hall effect sensor, or even a temperature sensor. The disclosure can be used to improve performance in single-stage or multi-stage hydraulic tools, but is not limited to two-stage hydraulic tools. The firmware algorithm, which modifies the motor control algorithm based on dynamic field weakening and sensor feedback, can be used to determine when the hydraulic cycle has transitioned from one stage to the next, for example, from stage one to stage two.

[0007] The firmware algorithm can be implemented in a variety of tools, including but not limited to cutting tools, punching tools, crimping tools, screwdrivers, riveting tools, ratchets, pressing tools, expander tools, drilling tools, or grinding tools. Each tool can have an actuator with a moving component configured to perform at least one function on a workpiece with which the tool comes into contact.

[0008] The present disclosure can utilize brushless motors. Brushless motors employ a rotating permanent magnet to change the direction of a magnetic field generated by surrounding stationary coils. Additionally, the strength and direction of the current in these coils can be varied to control the rotation of the permanent magnet. Brushless motors are advantageous because they can be continuously controlled at maximum torque. However, the disclosure could also be applied to brushed motors or other motor types. Brushless motors can be controlled by various control algorithms to alter or modify how the brushless motor operates. For example, a motor can be controlled to operate at a higher speed when unloaded, a lower speed when loaded, or with higher torque or peak power under specific loads.These modifications to the engine power can be used to optimize tool performance.

[0009] For tools in the low force range (e.g., six tons), a single-stage hydraulic pump is frequently used. For tools in the high force range (e.g., over six tons), a two-stage hydraulic pump is frequently used. However, in some embodiments, the disclosure can also be applied to tools with a three-stage or multi-stage hydraulic pump. Stage one is designed to deliver a large quantity of oil at low pressure, and stage two is designed to deliver a small quantity of oil at high pressure. Additional stages can be designed to deliver different quantities of oil under different pressure conditions.

[0010] Hydraulic crimping tools with two-stage pumps have significantly longer cycle times than tools with single-stage pumps. This is because more oil needs to be delivered than in a single-stage system, and the motor speed is determined by the torque and power of the second stage. While the disclosure describes a hydraulic crimping tool, it could also be applied to other types of hydraulic tools, such as hydraulic cutting tools or hydraulic punches, which may have different cycle times and oil delivery requirements.

[0011] The Fig. Figure 1A shows components of a hydraulic tool according to an exemplary embodiment. Although the exemplary implementation relates to an exemplary crimping tool, it is understood that the features of this disclosure can also be implemented in other similar hydraulic tools, such as cutting tools, punching tools, or drilling tools. The illustrated hydraulic tool 100 includes, as an example, a working head that uses a hex or hexagonal crimping head 114. The hydraulic crimping tool 100 includes an electric motor 102 configured to drive a pump 104 via a reduction gear 106. The pump 104 supplies a hydraulic circuit 124, which includes a hydraulic actuator cylinder 108 with a piston or plunger, with pressurized hydraulic fluid. However, the hydraulic actuator cylinder can also include other types of actuators, such as a rotary actuator or a linear actuator.

[0012] The Fig. Figure 1B shows an alternative hydraulic tool, including a punch-crimp head, according to an exemplary embodiment. In an example, and as shown in the Fig. As shown in Figure 1B, a user interface 136 can be positioned along an upper surface of the hydraulic tool. The hydraulic tool can also include a trigger switch 138, which is attached to the lower section of the hydraulic tool near a battery 212. However, the user interface can also be positioned on a side surface or a lower surface of the hydraulic tool, and the trigger switch can be attached along the upper section or a side section of the hydraulic tool.

[0013] The Fig. 1A and the Fig. Figure 2 shows the drive motor 102, the hydraulic pump 104, the torque converter or reduction gear 106, a fluid distribution network 124, a control unit 50, and a battery 212. The tool shaft 108 extends from the torque converter 106, the handle switch 114 is located at the top of the handle, and the fluid distribution network or hydraulic circuit 124 is connected to the fluid reservoir 214. The control unit 50 is connected to the data storage unit 80 and controls the drive motor 102 via the electrical feedback component 202. The battery 212 is located in the battery socket 134 of the power tool assembly 100. However, the battery 212 can also be located in another part of the power tool assembly, for example, in the handle or the motor housing.

[0014] The Fig. Figure 2 shows a block diagram of a hydraulic and electronic control system for the hydraulic tools 100 of the Fig. 1A and Fig. 1 B. The Fig. Figure 2 represents user interface components 20, the controller 50, a data storage unit 80, an electrical feedback component or current-sensing resistor 202, and the battery 212. The hydraulic tool 100 may include user interface components 20 that provide inputs to the power tool, such as a controller 50 (also referred to as a motor control unit or motor inverter). The controller 50 comprises a processor connected to the memory 80 and the user interface components 20. Such user interface components 20 may include, for example, a control panel, one or more switches, one or more pushbuttons, one or more interactive indicator lights, touchscreens or panels, other types of similar switches such as a trigger switch, and any combination of the above.Memory 80 can contain instructions which, when executed by the processor, cause the controller 50 to operate the tool 100. However, memory can also contain other types of data, such as sensor readings or user input.

[0015] The hydraulic pump 104 is connected to the drive motor 102, the torque converter 106 is connected to the hydraulic pump 104, the fluid distribution network 124 is connected to the hydraulic pump 104, and the pressure sensor 222 is connected to the control unit 50. In some embodiments, the hydraulic pump 104 may also be connected to another component, such as the torque converter 106 or the fluid distribution network 124. Furthermore, in some embodiments, the pressure sensor 222 may also be connected to another component, such as the hydraulic pump 104 or the fluid distribution network 124.

[0016] As in the Fig. As shown in Figure 2, the tool 100 comprises a fluid reservoir 214, which is connected to a hydraulic circuit 124 and the pump 104. The pressure sensor 222 (or a distance sensor, a battery current sensor, or a Hall effect sensor) can be connected to the controller 50, and a current-sensing resistor 202 can be connected in series with the controller 50 and the motor 102. The battery 212 can be detachably connected to a section of the hydraulic tool. As shown in the Fig. As shown in Figure 1A, the battery 212 can be detachably connected to a lower section 134 of the hydraulic tool, away from the crimping head. In some embodiments, the battery can be detachably connected to another section of the hydraulic tool, for example, the upper section or a side section. In some embodiments, the current-sensing resistor 202 can be connected in parallel to the control 50 and the motor 102.

[0017] The Fig. Figure 3 shows a flowchart of a firmware algorithm process 300 according to an embodiment of a method disclosed, which uses sensor readings as feedback to determine when the two-stage hydraulic cycle has transitioned from stage one to stage two. In a first step 302, the sensor readings are used to determine whether the motor is running. If the motor is running, the system (at 304) acquires the sensor readings while the motor is running. Subsequently, the system (at 306) averages the acquired sensor readings and compares the averaged sensor reading with a predetermined sensor value. If the averaged sensor reading is below the threshold, the motor control algorithm (at 310) can be adjusted based on the sensor feedback. If the averaged sensor reading is above a threshold, the motor commutation (at 308) can remain static. The Fig. The three steps shown are not exhaustive, and the system may include additional steps.

[0018] As in the Fig. As shown in Figure 3, a low-level firmware algorithm is used in this embodiment. However, in further embodiments, a high-level firmware algorithm can be used. This high-level firmware algorithm can be implemented in a flash memory chip and enable updates. In still further embodiments, the algorithm can be implemented in subsystems. These subsystems can be semi-independent devices that are part of a larger system. The firmware can be embedded in a central processing unit, a flash chip, a liquid crystal display, or another type of controller. The firmware can be a BIOS (Basic Input / Output System), an EFI (Extensible Firmware Interface), or another type of firmware.

[0019] The Fig.Figure 3 illustrates an algorithm with a looped event sequence. In other embodiments, however, this algorithm can be modified to include a linear event sequence that restarts upon completion. Furthermore, this embodiment illustrates various relevant measurements performed sequentially. In other embodiments, however, the measurements can be performed simultaneously or in a different order. In this embodiment, the controller 50 (at 302) determines whether the motor 102 is running. In some embodiments, this determination can be based on the controller 50 measuring the battery current draw using a current-sensing resistor 202 in series with the motor. The current-sensing resistor 202 can be a two-pole current-sensing resistor. In other embodiments, the current-sensing resistor 202 can be a four-pole current-sensing resistor, providing two poles for the current path.In other embodiments, the controller 50 can use other methods for detecting battery current consumption, including current-sensing amplifiers, coulomb counting, a separate battery monitoring circuit, tracking the offset voltage, or another suitable method for detecting battery current consumption.

[0020] When the motor 102 is running, the controller 50 (at 304) acquires the readings from the pressure sensor (or a distance sensor, a battery current sensor, or a Hall-effect sensor) to generate pressure sensor samples. For example, the controller 50 (at 304) can acquire the pressure sensor reading at least once per millisecond. The controller 50 can also calculate an average pressure sensor reading from the pressure sensor samples. In some embodiments, the controller can also sample the sensor reading at a different frequency, e.g., at least once per second or at least once per microsecond.

[0021] The controller 50 determines (at 306) whether the averaged pressure sensor reading exceeds a predefined pressure sensor reading (e.g., a transition point of the second stage). If the averaged pressure sensor reading exceeds the predefined pressure sensor reading, the controller 50 (at 308) determines that the two-stage hydraulic cycle has transitioned from stage one to stage two, changes the motor control algorithm, and generates a command to start a static motor commutation sequence. However, if the averaged pressure sensor reading does not exceed the predefined pressure sensor reading, the controller 50 (at 310) determines that the two-stage hydraulic cycle has not transitioned from stage one, does not change the motor control algorithm, and continues operation of the tool using the dynamic field weakening motor control algorithm.In some embodiments, the controller 50 can also change the motor control algorithm based on another type of feedback, e.g., user input or diagnostic test results.

[0022] In some embodiments of the disclosure, process 300 can be used to detect, using a sensor, that a two-stage hydraulic cycle has transitioned from stage one to stage two, and to dynamically change the motor control algorithm if an averaged sensor reading is higher than a predetermined sensor reading. The process can also be used to detect that a multi-stage hydraulic cycle has transitioned from one stage to another. In some embodiments, the process can use a different type of sensor, and the process can dynamically change the motor control algorithm if a different type of sensor reading is higher than a predetermined sensor reading.

[0023] In a particular embodiment of the disclosed technology, dynamic field weakening is used as the control algorithm. Field weakening, also called flux weakening, can be used to increase the speed of an electric motor beyond its rated power at the expense of reduced torque. This method is particularly useful in scenarios where a higher motor speed is desired and lower torque is acceptable. Conversely, the use of field weakening can be omitted when higher torque is required and lower motor speed is acceptable.

[0024] Field weakening involves adjusting the phase of the motor drive current. This adjustment allows the motor to operate with a drive voltage lower than the motor's back EMF. As mentioned earlier, the present disclosure may include a brushless motor containing a permanent magnet. These brushless motors may be designed with rotor magnets directly opposite an air gap to a stator. Alternatively, the magnets may be mounted inside the rotor, with the flux being conducted to the gap through a permeable magnetic material.

[0025] Each of these configurations can be effectively used with dynamic field weakening and offers its own advantages for different applications. Generally, field weakening keeps the available power of a motor nearly constant over a speed ratio of two to one. Furthermore, the higher available voltage made possible by field weakening allows for higher output power.

[0026] Within the scope of this disclosure, the motor control algorithm can be used to increase the motor's idle speed at the expense of increased current and reduced battery life. Field weakening can be employed to accelerate the first stage of the crimping process at increased current and reduced battery life, and then, after reaching the second stage, to revert to static commutation to extend battery life. This approach effectively reduces the overall cycle time and contributes to preserving battery life.

[0027] It is understood that the disclosure, in its application, is not limited to the design details and arrangement of components set forth in the following description or illustrated in the following drawings. The disclosure may have other embodiments and may be practiced or implemented in various ways. It is also understood that the language and terminology used herein are descriptive and should not be considered limiting. The use of "including," "comprising," or "having" and variations thereof is intended to encompass the elements listed thereafter and their equivalents, as well as additional elements. Unless otherwise specified or limited, the terms "assembled," "connected," "supported," and "coupled," and variations thereof, are used broadly and include both direct and indirect assembly, joining, supporting, and coupling.Furthermore, the terms "connected" and "coupled" are not limited to physical or mechanical connections or couplings.

[0028] Unless otherwise restricted or defined, the discussion of certain directions here is only exemplary and in relation to specific embodiments or relevant illustrations. For example, the discussion of elements as "top," "front," or "back" is generally intended only as a description of the orientation of these elements relative to a frame of reference of a particular example or representation. Accordingly, for instance, in some arrangements or embodiments, an "top" element may sometimes be positioned below a "bottom" element (and so on). Furthermore, references to specific rotations or other movements (e.g., counterclockwise rotation) are generally to be understood only as a description of the movement relative to a frame of reference of a particular example.

[0029] In some embodiments, aspects of the disclosure, including computer-based implementations of methods according to the disclosure, can be implemented as a system, method, device, or article of manufacture using standard programming or engineering techniques to create software, firmware, hardware, or any combination thereof for controlling a processor device (e.g., a serial or parallel general-purpose or special-purpose processor chip, a single- or multi-core chip, a microprocessor, a field-programmable gate array, any combination of control unit, arithmetic logic unit, and processor register, etc.), a computer (e.g., a processor device operationally coupled to a memory), or any other electronically operated controller for implementing the aspects described herein.Accordingly, embodiments of the disclosure can be implemented, for example, as an instruction set embodied on a non-volatile, computer-readable medium, such that a processor can execute the instructions based on reading them from the computer-readable medium. Some embodiments of the disclosure may include (or utilize) a control device such as an automation device, a specialized or general-purpose computer with various computer hardware, software, firmware, etc., as explained below. Specific examples of control devices include a processor, a microcontroller, a field-programmable gate array, a programmable logic controller, logic gates, etc., as well as other typical components known in the art for implementing corresponding functions (e.g., memory, communication systems, power sources, user interfaces, and other inputs, etc.).The term “product” as used here encompasses a computer program that is accessible from any computer-readable device, carrier (e.g., non-volatile signals) or medium (e.g., non-volatile media).

[0030] Certain operations of processes according to the disclosure, or of systems that perform these processes, may be schematically illustrated in the figures or otherwise discussed herein. Unless otherwise specified or limited, the illustration of certain operations in the figures in a particular spatial sequence does not necessarily require that these operations be performed in a specific sequence corresponding to that spatial sequence. Accordingly, certain operations illustrated in the figures or otherwise disclosed herein may be performed in a different sequence than expressly illustrated or described, depending on the specific embodiments of the disclosure.Furthermore, in some embodiments, certain operations can be performed in parallel, including through dedicated parallel processing devices or separate computer devices configured to work together as part of a larger system.

[0031] Unless otherwise specified or limited, the terms "component," "system," "module," and the like, in the context of computer implementation, are intended to encompass all or part of computer-related systems, including hardware, software, a combination of hardware and software, or running software. A component may be, for example, a processor device, a process running (or executable) by a processor device, an object, an executable file, an execution thread, a computer program, or a computer. For example, both an application running on a computer and the computer itself can be a component. One or more components (or systems, modules, etc.)) can be located within a process or execution thread, be localized on one computer, be distributed across two or more computers or other processing devices, or be contained within another component (or system, module, etc.).

[0032] Various features and advantages are set out in the following claims.

Claims

[1] A method for modifying a motor control algorithm in a power tool, the power tool comprising a motor, a stator and a sensor, the method comprising: Operating the motor according to dynamic field weakening by operating the motor above a rated speed, thereby weakening a magnetic field of the stator; measuring sensor readings; scanning the sensor readings while the engine is running to generate sensor scan values; Calculating an averaged sensor measurement value by averaging the sensor sample values; comparing the average sensor measurement value with a predetermined sensor value; Continuing operation according to the dynamic field weakening if the averaged sensor reading has not exceeded the preset sensor value; and Changing the motor control algorithm to a static motor commutation sequence when the averaged sensor reading exceeds the specified sensor value. [2] The method according to claim 1, wherein the power tool is a hydraulic tool; and further comprising determining that a hydraulic cycle has transitioned from stage one to stage two when the averaged sensor reading exceeds the predetermined sensor value. [3] The method according to claim 1 and further comprising measuring measured values ​​from at least one of a pressure sensor, distance sensor, battery current sensor or Hall effect sensor. [4] The method according to claim 1 and further comprising measuring pressure sensor readings using a pressure sensor in series with a controller and the motor. [5] The method according to claim 1 and further comprising measuring measured values ​​from a pressure sensor and averaging sampled pressure sensor measured values. [6] The method according to claim 1 and further comprising measuring measured values ​​from a current-sensing resistor in series with the motor. [7] The method according to claim 6, further comprising measuring measured values ​​of at least one of a two-pole current-sensing resistor or a four-pole current-sensing resistor. [8] The method according to claim 1 and further comprising detecting the battery current consumption using at least one of a current measuring amplifier, coulomb counting or battery monitoring circuit. [9] The method according to claim 1 and further comprising sampling the sensor measurements in a range between about once per microsecond and about once per second. [10] The method according to claim 1, wherein the power tool is a hydraulic tool; and further comprising determining whether the averaged sensor reading exceeds the predetermined sensor value in order to determine whether a two-stage hydraulic cycle has transitioned from stage one to stage two. [11] The method according to claim 10 and further comprising generating a command to start a static motor commutation sequence when the two-stage hydraulic cycle has transitioned from stage one to stage two. [12] The method according to claim 10 and further comprising continuing the operation according to the dynamic field weakening when the two-stage hydraulic cycle has not transitioned from stage one to stage two. [13] The method according to claim 1 and further comprising changing the motor control algorithm to the static motor commutation sequence to reduce power consumption. [14] The method according to claim 1 and further comprising operation according to dynamic field weakening despite torque reduction. [15] The method according to claim 1 further comprising operation according to dynamic field weakening to keep the available motor power nearly constant over a speed ratio. [16] The method according to claim 1 and further comprising operation according to dynamic field weakening to increase the current and an idle speed of the motor. [17] The method according to claim 1, wherein the power tool is a hydraulic crimping tool; and further comprising accelerating the first stage of a crimping process at increased current and reduced battery life. [18] The method according to claim 17 and further comprising switching to the static motor commutation sequence to extend battery life. [19] A hydraulic power tool comprising: a motor with a stator; a pump; a fluid distribution network in fluid connection with the pump; a pressure sensor in conjunction with the fluid distribution network; and a control unit connected to the motor and the pressure sensor; wherein the control operates the motor according to the dynamic field weakening by operating the motor above a rated speed by weakening a magnetic field of the stator; the control unit measures pressure sensor readings; The control unit records the pressure sensor readings while the engine is running to generate pressure sensor sample values; The controller calculates an average pressure sensor reading by averaging the pressure sensor sample values; The controller compares the averaged pressure sensor reading with a predefined pressure sensor value; and The control system continues operation according to the dynamic field weakening if the averaged pressure sensor reading has not exceeded the preset pressure sensor value; and The controller changes a motor control algorithm to a static motor commutation sequence when the averaged pressure sensor reading exceeds the specified pressure sensor value. [20] The hydraulic power tool according to claim 19, wherein the control system determines that a hydraulic cycle has transitioned from stage one to stage two when the averaged pressure sensor reading exceeds the predetermined pressure sensor value.

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