Electric tool and control method thereof

Abstract

The invention discloses an electric tool and a control method thereof. The electric tool comprises: a functional member; a motor; a power supply device; the controller is connected with the motor and used for controlling operation of the motor; the detection device is connected with the motor and the controller and is configured to detect the duration of each phase of the motor, and the duration of each phase of the motor is the duration of a motor rotor in each electrical angle sector; the controller is configured to obtain the rising phase duration and the falling phase duration of the motor according to the duration of each phase of the motor, and judge whether the motor has a non-uniform commutation phenomenon or not based on the rising phase duration and the falling phase duration; under the condition that the motor has an uneven commutation phenomenon, dynamically adjusting a rising commutation point and / or a falling commutation point of the motor based on the size relationship between the rising phase duration and the falling phase duration; the floating phase voltage rises from low in the rising phase duration, and the floating phase voltage drops from high in the falling phase duration.

Description

Technical Field

[0001] The present application relates to the technical field of electric tools, and in particular to an electric tool and a control method thereof. Background Art

[0002] The motor in the power tool runs under the control of the controller. The three-phase motor has six equal electrical angle sectors. The time that the motor rotor rotates in each electrical angle sector is the phase duration. However, when the power tool is overloaded, the six phase durations corresponding to the six electrical angle sectors may fluctuate due to the fluctuation of the characteristic parameters of components such as inductance. The fluctuation of the motor phase duration may affect the judgment of the power tool's stall protection, causing the power tool to enter the stall protection prematurely, thereby having a negative impact on the performance, efficiency and user experience of the power tool and its motor.

[0003] This section provides background information related to the present application which is not necessarily prior art. Summary of the invention

[0004] One object of the present application is to solve or at least alleviate part or all of the above problems. To this end, one object of the present application is to provide an electric tool and a control method thereof.

[0005] In order to achieve the above objectives, this application adopts the following technical solutions:

[0006] An electric tool comprises: a functional part; a motor for driving the functional part to operate; a power supply device, at least for supplying power to the motor; a controller, connected to the motor, for controlling the operation of the motor; wherein the electric tool also comprises: a detection device, connected to the motor and the controller, and configured to detect the duration of each phase of the motor; the duration of each phase of the motor is the duration during which the motor rotor is located in each electrical angle sector; the controller is configured to: obtain the rising phase duration and the falling phase duration of the motor from the duration of each phase of the motor, and based on the rising phase duration and the falling phase duration, determine whether the motor has uneven commutation; in the case of uneven commutation of the motor, dynamically adjust the rising commutation point and / or the falling commutation point of the motor based on the size relationship between the rising phase duration and the falling phase duration; the floating phase voltage increases from low during the rising phase duration, and decreases from high during the falling phase duration.

[0007] In some embodiments, the controller is configured to: determine that the motor has uneven commutation when the difference between the rising phase duration and the falling phase duration exceeds a preset difference threshold; or determine that the motor has uneven commutation when the ratio of the rising phase duration to the falling phase duration exceeds a preset ratio threshold.

[0008] In some embodiments, the motor is a three-phase motor having six electrical angle sectors and corresponding six-phase durations, where the six-phase durations are the durations of alternating rising phases and falling phases.

[0009] In some embodiments, the rising phase duration and the falling phase duration are the durations of two adjacent phases; or, the rising phase duration is the sum of the durations of three rising phases generated by one rotation of the motor rotor, and the falling phase duration is the sum of the durations of three falling phases generated by one rotation of the motor rotor.

[0010] In some embodiments, the controller is configured to: adjust the first proportional point corresponding to the rising commutation point to change the triggering timing of the rising commutation point, and control the motor to switch from the current rising phase to the next phase when the floating phase voltage of the motor rises from the lowest point to the first proportional point; and / or adjust the second proportional point corresponding to the falling commutation point to change the triggering timing of the falling commutation point, and control the motor to switch from the current falling phase to the next phase when the floating phase voltage of the motor drops from the highest point to the second proportional point.

[0011] In some embodiments, the controller is configured to: when uneven commutation occurs in the motor, if the duration of the rising phase is greater than the duration of the falling phase, reduce the first proportional point, and / or reduce the second proportional point.

[0012] In some embodiments, the controller is configured to: when uneven commutation occurs in the motor, if the duration of the rising phase is shorter than the duration of the falling phase, increase the first proportional point, and / or increase the second proportional point.

[0013] In some embodiments, the controller is configured to adjust the first proportional point within a preset first proportional range, and / or adjust the second proportional point within a preset second proportional range until the uneven commutation phenomenon of the motor is eliminated.

[0014] In some embodiments, the first ratio ranges from 0.5 to 0.8; the second ratio ranges from 0.2 to 0.5.

[0015] In some embodiments, the controller is configured to: adjust the first timer count corresponding to the rising commutation point to change the triggering timing of the rising commutation point, and control the motor to switch to the next phase when the timer increment reaches the first timer count after the motor enters the rising phase; and / or adjust the second timer count corresponding to the falling commutation point to change the triggering timing of the falling commutation point, and control the motor to switch to the next phase when the timer increment reaches the second timer count after the motor enters the falling phase.

[0016] An electric tool comprises: a functional part; a motor for driving the functional part to operate; a power supply device, at least for supplying power to the motor; a controller connected to the motor and used to control the operation of the motor; wherein the controller is configured to: control the duration of each phase during the operation of the motor so that the duration of each phase of the motor remains substantially equal; the duration of each phase of the motor is the duration that the motor rotor is located in each electrical angle sector.

[0017] A control method for an electric tool comprises: a detection device of the electric tool detects the duration of each phase of a motor of the electric tool; the duration of each phase of the motor is the duration that the motor rotor is located in each electrical angle sector; a controller of the electric tool obtains the rising phase duration and the falling phase duration of the motor from the duration of each phase of the motor, and judges whether the motor has uneven commutation based on the rising phase duration and the falling phase duration; when the motor has uneven commutation, the controller dynamically adjusts the rising commutation point and / or the falling commutation point of the motor based on the size relationship between the rising phase duration and the falling phase duration; wherein, the floating phase voltage increases from low to high within the rising phase duration, and the floating phase voltage decreases from high to low within the falling phase duration.

[0018] The benefit of the present application lies in: detecting the duration of each phase of the motor and thereby determining whether the motor currently has uneven commutation, and then eliminating the uneven commutation phenomenon by dynamically adjusting the rising commutation point and / or the falling commutation point when the phenomenon exists, thereby avoiding problems such as misjudgment of stall protection caused by fluctuations in the duration of each phase when the power tool is overloaded, etc., ensuring that the motor in the power tool can always operate normally and smoothly, which is beneficial to improving tool efficiency and performance and optimizing user experience. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a three-dimensional diagram of a power tool as an embodiment of the present application;

[0020] Figure 2 yes Figure 1 The electric control schematic diagram of the electric tool shown;

[0021] Figure 3 yes Figure 2 A schematic diagram of the voltage of each phase in the motor shown;

[0022] Figure 4a yes Figure 2 A schematic diagram of the uneven commutation phenomenon in a motor where the duration of the rising phase is longer than the duration of the falling phase;

[0023] Figure 4b yes Figure 2 A schematic diagram of the commutation unevenness phenomenon in a motor where the duration of the rising phase is shorter than the duration of the falling phase is shown;

[0024] Figure 5It is a flow chart of a control method of an electric tool as an embodiment of the present application. DETAILED DESCRIPTION

[0025] Before any embodiments of the application are explained in detail, it is to be understood that the application is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the above drawings.

[0026] In this application, the terms "comprises", "includes", "has" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device that includes a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of more restrictions, an element defined by the sentence "comprises a ..." does not exclude the presence of other identical elements in the process, method, article or device that includes the element.

[0027] In this application, the term "and / or" is a description of the association relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. In addition, the character " / " in this application generally indicates that the related objects before and after are in an "and / or" relationship.

[0028] In the present application, the terms "connect", "combine", "couple", and "install" may refer to direct connection, combination, coupling, or installation, or indirect connection, combination, coupling, or installation. For example, direct connection refers to two parts or components being connected together without the need for an intermediate piece, and indirect connection refers to two parts or components being connected to at least one intermediate piece respectively, and the two parts or components being connected via the intermediate piece. In addition, "connect" and "couple" are not limited to physical or mechanical connections or couplings, and may include electrical connections or couplings.

[0029] In the present application, it will be understood by those of ordinary skill in the art that relative terms (e.g., "about," "approximately," "substantially," etc.) used in conjunction with quantities or conditions include the values ​​and have the meaning indicated by the context. For example, the relative terms include at least the degree of error associated with the measurement of a specific value, the tolerances caused by manufacturing, assembly, and use associated with a specific value, and the like. Such terms should also be considered to disclose a range defined by the absolute values ​​of the two endpoints. Relative terms may refer to plus or minus a certain percentage (e.g., 1%, 5%, 10% or more) of the indicated value. Numerical values ​​that do not use relative terms should also be disclosed as specific values ​​with tolerances. In addition, "substantially" may refer to plus or minus a certain degree (e.g., 1 degree, 5 degrees, 10 degrees or more) on the basis of the indicated angle when expressing a relative angular position relationship (e.g., substantially parallel, substantially perpendicular).

[0030] In this application, it will be understood by those skilled in the art that the function performed by a component can be performed by one component, multiple components, one part, or multiple parts. Similarly, the function performed by a part can also be performed by one part, one component, or a combination of multiple parts.

[0031] In the present application, the terms "upper", "lower", "left", "right", "front", "back" and other directional words are described based on the orientation and positional relationship shown in the accompanying drawings, and should not be understood as limiting the embodiments of the present application. In addition, in the context, it is also necessary to understand that when it is mentioned that an element is connected to another element "upper" or "lower", it can not only be directly connected to another element "upper" or "lower", but also indirectly connected to another element "upper" or "lower" through an intermediate element. It should also be understood that directional words such as upper side, lower side, left side, right side, front side, back side, etc. not only represent the positive orientation, but can also be understood as the lateral orientation. For example, the bottom can include directly below, lower left, lower right, lower front, and lower back, etc.

[0032] In this application, the terms "controller", "processor", "central processing unit", "CPU", and "MCU" are interchangeable. When a unit "controller", "processor", "central processing unit", "CPU", or "MCU" is used to perform a specific function, unless otherwise specified, these functions can be performed by a single unit or multiple units.

[0033] In the present application, the terms “device”, “module” or “unit” may be implemented in the form of hardware or software to achieve specific functions.

[0034] In this application, the terms "calculate", "judge", "control", "determine", "identify", etc. refer to the operations and processes of a computer system or similar electronic computing device (e.g., controller, processor, etc.).

[0035] The technical solution proposed in this application is described in detail below with reference to the accompanying drawings and specific embodiments.

[0036] Figure 1 An electric tool 100 is shown as one embodiment in the present application. Figure 1 The electric tool 100 shown is an electric circular saw 100a. The electric tool 100 in other embodiments may also be other types of handheld electric tools such as a jigsaw, a reciprocating saw, an electric drill, an impact wrench, or a bench-type tool such as a miter saw or a table saw, or an outdoor power equipment such as a lawn mower or a snow blower. It is understandable that the electric tool 100 using the technical solution of the present application is not limited to the electric circular saw 100a, nor is it limited to the tool categories described above.

[0037] refer to Figure 1 The electric tool 100 includes a housing 10, an operating member 20 and a functional member 30. The housing 10 constitutes the main body of the electric tool 100, which connects or supports the above-mentioned components and forms a housing space, which can accommodate or partially accommodate the above-mentioned components. The operating member 20 is operated by the user to start or stop the motor 40 to be described later, or is operated by the user to adjust the speed of the motor 40 or achieve other multiple functions. The functional member 30 is a component of the electric tool 100 that actually performs operations such as cutting, tightening, grinding, and impacting. Taking the electric circular saw 100a as an example, its functional member 30 is a circular saw blade 31. The functional members 30 of other electric tools 100 may also be chains, drill bits, etc.

[0038] refer to Figure 2 In addition to the housing 10, the operating part 20 and the functional part 30, the electric tool 100 also includes a motor 40, a power supply device 50, a controller 60 and a detection device 70. The motor 40 is the prime mover in the electric tool 100. When the motor shaft of the motor 40 rotates, it can drive the functional part 30 to operate directly or indirectly through a transmission component. The power supply device 50 can at least provide electrical energy to the motor 40, and can also supply power to the controller 60, the detection device 70 or other related circuits. In some examples, the power supply device 50 is a battery pack 51, which is detachably connected to the electric tool 100. In other examples, the power supply of the electric tool 100 can also be realized by using AC power, AC power and cooperating with a power adapter or related circuits such as voltage conversion, rectification, and voltage stabilization.

[0039] The controller 60 can be an MCU (Microcontroller Unit), ARM (Advanced Reduced Instruction Set Computing Machine), DSP (Digital Signal Processor), etc. It is electrically connected to the motor 40, can run relevant control programs and output control signals to the motor 40, so that the motor 40 can operate in the intended correct manner. Usually, a driving device such as a three-phase inverter bridge, an integrated driving chip, etc. should also be connected between the controller 60 and the motor 40. The control signal output by the controller 60 will be converted into a driving signal through the driving device that actually drives the motor 40 to rotate.

[0040] The motor 40 can be a three-phase motor 40, and the three phases of the three-phase motor 40 can be respectively recorded as phase A, phase B and phase C. Although the number of windings, the connection method, the number of magnetic poles, etc. can be different, the three-phase motor 40 should have six electrical angle sectors. The six electrical angle sectors have a rotation order and total 360°. The six consecutive electrical angle sectors can respectively correspond to the six stages of the AB phase, AC phase, BC phase, BA phase, CA phase, and CB phase of the three-phase motor 40 being turned on in sequence. The corresponding relationship between the two represents that in a stage where two phases of the three-phase motor are turned on, the motor rotor will be affected by the corresponding stator magnetic field and will rotate in the corresponding electrical angle sector. In other words, the motor rotor will pass through the above six electrical angle sectors under the above six two-phase conduction conditions to complete a rotation. Figure 2 As shown, the six switch tubes in the driving device can be respectively recorded as Q1, Q2, Q3, Q4, Q5, and Q6. When the controller 60 drives the motor 40 to rotate, it will output a control signal that can turn on two switch tubes in the driving device to achieve the conduction of two phases in the corresponding three-phase motor 40. Specifically, the controller 60 can output a control signal to sequentially turn on the switch tubes Q1Q4, Q1Q2, Q3Q2, Q3Q6, Q5Q6, and Q5Q4 in the driving device. Correspondingly, the AB phase, AC phase, BC phase, BA phase, CA phase, and CB phase of the three-phase motor 40 can be sequentially turned on, thereby achieving the drive and control of the rotation of the motor 40. It can be understood that the reversal process of the motor 40 can also be deduced based on the above, and will not be repeated.

[0041] The detection device 70 is electrically connected to the motor 40 and the controller 60, detects the duration of each phase of the motor 40 and transmits the measured duration of each phase to the controller 60. Specifically, the detection device 70 detects the duration of the six phases of the three-phase motor 40. It should be noted that the "phase" of the "phase duration" described here is different from the "phase" of the "three-phase motor". The six-phase duration is the duration of the six stages in which the AB phase, AC phase, BC phase, BA phase, CA phase, and CB phase in the three-phase motor 40 are sequentially turned on, that is, the duration of the motor rotor being located in six electrical angle sectors.

[0042] There are multiple optional implementations for the detection device 70 to detect the duration of each phase of the motor 40. Specifically, the detection device 70 can directly obtain or indirectly deduce the duration of each phase of the motor 40 based on various motor 40 parameters such as the phase voltage and phase current of the motor 40. The specific process of deduce the duration of each phase can be adaptively designed depending on whether the motor 40 is equipped with a position sensor such as a Hall sensor, and the specific control algorithm used by the controller 60. In one embodiment, the detection device 70 can use a timer to count the duration of each phase, and the size of the timer count value under each phase represents the length of each phase.

[0043] In order to clarify the following scheme, the six-phase duration of the three-phase motor 40 is further described in detail here. Figure 3 , Figure 3 The waveforms of the A-phase voltage, B-phase voltage and C-phase voltage of the three-phase motor 40 under ideal conditions are shown during one rotation of the motor rotor. The six phases of the three-phase motor can be divided and defined as a rising phase and a falling phase, wherein the rising phase is a phase in which the floating phase voltage rises from low to high. For example, in the stage in which the AC phase of the three-phase motor 40 is turned on, since the previous phase is the AB phase turned on and the next phase is the BC phase turned on, the current floating phase voltage, i.e., the B phase voltage, will experience a process of rising from low in the current stage, so the stage in which the AC phase is turned on is the rising phase. The falling phase is a phase in which the floating phase voltage decreases from high to low. For example, in the stage in which the BC phase of the three-phase motor 40 is turned on, since the previous phase is the AC phase turned on and the next phase is the BA phase turned on, the current floating phase voltage, i.e., the A phase voltage, will experience a process of decreasing from high in the current stage, so the stage in which the BC phase is turned on is the falling phase. In addition, it is not difficult to find that according to the conduction sequence described above, during one rotation of the motor rotor, the rising phase and the falling phase will appear alternately. The above six-phase duration includes the duration of three rising phases and the duration of three falling phases. Under ideal conditions, the duration of each phase should be equal.

[0044] If a static solution that does not consider the changes in the working conditions of the power tool 100 is always used to control the operation of the motor 40, the six phases of the three-phase motor 40 are generally of unequal length. This phenomenon can also be called uneven phase change in motor control. Of course, in addition to the unequal duration of each phase, the uneven phase change can also have other external manifestations. In some embodiments, the solution can also introduce the detection of other parameters to verify whether the motor has uneven phase change. In scenarios where the temperature rises, such as when the power tool 100 is overloaded, the characteristic parameters of components such as inductance may produce more significant fluctuations, resulting in more significant fluctuations in the duration of each phase of the motor 40. The operation of the motor 40 will become unsmooth, and it may affect the judgment of the controller 60 in the power tool 100 on the stall protection. For example, assuming that the duration of each phase of the motor 40 is theoretically 900us, the reference duration for the controller 60 to judge whether the motor 40 needs to enter the stall protection is 1000us. If the duration of a phase of the motor 40 exceeds 1000us due to the above problem, the controller 60 will misjudge. And the power tool 100 enters the stall protection prematurely. This misjudgment cannot be solved simply by increasing the reference time of the stall protection. Only increasing the reference time will increase the current of the relevant circuit when the tool is overloaded, and increase the probability of MOS damage. Therefore, the above-mentioned uneven motor commutation phenomenon may have an adverse effect on the efficiency, performance and user experience of the power tool 100. The present application will improve the uneven commutation phenomenon by setting the detection device 70 described above and designing the controller 60 configuration to be described later to ensure that the power tool 100 can perform various operations efficiently and accurately.

[0045] After obtaining the duration of each phase of the motor 40 measured by the detection device, the controller 60 can determine the duration of the rising phase and the duration of the falling phase. Among them, the rising phase duration includes the duration of one or more rising phases, and the falling phase duration includes the duration of one or more falling phases. In addition, usually, the number of rising phases included in the rising phase duration is equal to the number of falling phases included in the falling phase duration, so as to facilitate subsequent comparison and judgment. In some embodiments, after the controller 60 obtains the duration of each phase of the motor 40, because the six-phase duration in one cycle is the duration of the alternating rising phase and the falling phase, the rising phase duration and the falling phase duration can be determined by the duration of any two adjacent phases. In this embodiment, the rising phase duration and the falling phase duration are one phase duration, such as Figure 3 As shown, the duration of the rising phase can be the duration T of the AC phase conduction stage. u1 , the duration of the falling phase can be the duration of the AB phase conduction phase T d1 ; Or, the duration of the rising phase is the duration of the BA phase conduction phase T u2 , the duration of the falling phase is the duration of the BC phase conduction phase T d2 Alternatively, the duration of the rising phase is the duration of the CB phase conduction phase T u3The duration of the falling phase is the duration of the conduction phase of the CA phase T d3 In other embodiments, after the controller 60 obtains the duration of each phase of the motor 40, it can determine the sum of the durations of the three rising phases in one cycle as the rising phase duration, and determine the sum of the durations of the three falling phases in the same cycle, that is, the sum of the durations of the other three phases in the same cycle as the falling phase duration. In this embodiment, the rising phase duration and the falling phase duration are the three-phase durations. Figure 3 As shown, the duration of the rising phase is T u1 +T u2 +T u3 The duration of the falling phase is T d1 +T d2 +T d3 .

[0046] Then, the controller 60 can determine whether the motor 40 of the electric tool 100 currently has uneven commutation based on the determined rising phase duration and falling phase duration. In some embodiments, the controller 60 can make a difference between the rising phase duration and the falling phase duration, and determine whether the difference between the two exceeds a preset difference threshold, and then determine that the motor 40 has uneven commutation if it is. In other embodiments, the controller 60 can make a quotient between the rising phase duration and the falling phase duration, and determine whether the ratio between the two exceeds a preset ratio threshold, and then determine that the motor 40 has uneven commutation if it is.

[0047] refer to Figure 4a to Figure 4b , taking the case where the rising phase duration and the falling phase duration are the same phase duration and adjacent to each other as an example, the rising phase duration is Figure 3 The duration of the AC phase conduction phase T u1 The duration of the falling phase is Figure 3 The duration of the BC phase conduction phase T d2 The uneven commutation phenomenon in the motor 40 can be divided into two categories. When the difference or ratio of the two exceeds the corresponding threshold, one of them is as follows. Figure 4a As shown, the duration of the rising phase is longer than that of the falling phase, and the duration of the AC phase conduction phase is T u1 Greater than the duration T of the BC phase conduction phase d2 Second, if Figure 4b As shown, the duration of the rising phase is shorter than the duration of the falling phase, and the duration of the AC phase conduction phase T u1 Less than the duration T of the BC phase conduction phase d2 .

[0048] Then, after determining that the motor 40 of the electric tool 100 currently has uneven commutation, the controller 60 can dynamically adjust the rising commutation point and / or the falling commutation point of the motor 40 based on the size relationship between the rising phase duration and the falling phase duration, so as to eliminate the uneven commutation of the motor 40. Continuing from the above, the controller 60 outputs a control signal to turn on the switch tube in the drive device to turn on two different phases of the three phases. The trigger point in the above control action that triggers the controller 60 to switch the control signal it outputs so that the turned-on switch tube or the two phases of the turned-on three-phase motor 40 are switched after a certain delay is called the commutation point. The commutation point is the triggering time for the controller 60 to control the motor 40 to switch from the current phase to the next phase. The rising commutation point is defined as the trigger point for switching to the next phase in the rising phase, and the falling commutation point is defined as the trigger point for switching to the next phase in the falling phase.

[0049] The controller 60 dynamically adjusts the rising commutation point and / or the falling commutation point, and there are multiple optional implementations. In one implementation, the controller 60 can control the motor 40 to switch between the six phases based on the proportional point. When there is uneven commutation, the controller 60 eliminates the uneven commutation by dynamically adjusting the proportional point.

[0050] The proportional point is the ratio of the floating phase voltage to the upper bridge open phase voltage. When the floating phase voltage rises or falls to the corresponding proportional point after the freewheeling ends, the controller 60 controls the motor 40 to switch from the current phase to the next phase. The first proportional point corresponds to the rising switching point. Taking the AC phase conduction stage as an example, the floating phase voltage is the B phase voltage, the upper bridge open phase voltage is the A phase voltage, and the amplitude of the upper bridge open phase voltage is regarded as 1 unit. Assuming that the original first proportional point is 0.6, when the floating phase voltage, that is, the amplitude of the B phase voltage, rises from the lowest point 0 to the first proportional point 0.6 after the freewheeling ends, the controller 60 controls the motor 40 to switch from the AC phase conduction stage to the BC phase conduction stage. The second proportional point corresponds to the falling commutation point. Taking the BC phase conduction stage as an example, the floating phase voltage is the A phase voltage, and the upper bridge open phase voltage is the C phase voltage. Assuming that the original second proportional point is 0.4, after the floating phase voltage, that is, the amplitude of the A phase voltage, drops from the highest point 1 to the second proportional point 0.4 after the continuous flow ends, the controller 60 controls the motor 40 to switch from the BC phase conduction stage to the BA phase conduction stage.

[0051] In some embodiments, after the controller 60 determines that the motor 40 has uneven commutation, Figure 4a When the duration of the rising phase is longer than the duration of the falling phase, the first proportional point corresponding to the rising switching point can be reduced, and / or the second proportional point corresponding to the falling switching point can be reduced. Figure 4a , when the duration of the AC phase conduction phase T u1 Greater than the duration T of the BC phase conduction phased2 , the controller 60 can reduce the first proportional point and / or the second proportional point. Assuming that the original first proportional point is 0.6, the second proportional point is 0.4, and the upper bridge open phase voltage amplitude is 1 unit, if the first proportional point is reduced to 0.59, the commutation point of the AC phase conduction stage changes from the original B phase voltage amplitude rising to 0.6 to trigger the commutation to rising to 0.59 to trigger the commutation, and the duration T of the AC phase conduction stage u1 Relatively reduce the duration T of the BC phase conduction phase d2 Gradually balanced; if the second commutation point is reduced to 0.39, the commutation point of the BC phase conduction stage changes from the original A phase voltage amplitude dropping to 0.4 to trigger the commutation to dropping to 0.39 to trigger the commutation, and the duration of the BC phase conduction stage T d2 Relatively increase with the duration T of the AC phase conduction stage u1 Gradually balance, thus eliminating uneven commutation.

[0052] In some other embodiments, after the controller 60 determines that the motor 40 has uneven commutation, Figure 4b In the case where the duration of the rising phase is less than the duration of the falling phase, the first proportional point corresponding to the rising switching point can be increased, and / or the second proportional point corresponding to the falling switching point can be increased. Figure 4b , when the duration of the AC phase conduction phase T u1 Less than the duration T of the BC phase conduction phase d2 , the controller 60 can increase the first proportional point and / or the second proportional point. If the first proportional point is increased to 0.61, the switching point of the AC phase conduction stage changes from the original B phase voltage amplitude rising to 0.6 triggering the switching to rising to 0.61 triggering the switching, and the duration T of the AC phase conduction stage u1 Relatively increase with the duration T of the BC phase conduction phase d2 Gradually balanced; if the second commutation point increases to 0.41, the commutation point of the BC phase conduction stage changes from the original A phase voltage amplitude dropping to 0.4 to trigger the commutation to dropping to 0.41 to trigger the commutation, and the duration of the BC phase conduction stage T d2 Relatively reduced to the duration T of the AC phase conduction phase u1 Gradually balance to eliminate uneven commutation.

[0053] In some embodiments, the controller 60 adjusts the first proportional point and / or the second proportional point in a stepping manner, and the step amount of a single adjustment of the first proportional point and / or the second proportional point ranges from 0.002 to 0.01.

[0054] In some embodiments, the controller 60 adjusts the above-mentioned proportional points within a corresponding preset proportional range. Specifically, the controller 60 can dynamically adjust the first proportional point within the first proportional range, and its value does not exceed the upper and lower limits of the first proportional range, and / or dynamically adjust the second proportional point within the second proportional range, and its value does not exceed the upper and lower limits of the second proportional range, until the uneven commutation of the motor 40 is eliminated. In some embodiments, the first proportional range corresponding to the rising commutation point or the first proportional point is 0.5 to 0.8, and the second proportional range corresponding to the falling commutation point or the second proportional point is 0.2 to 0.5. In other embodiments, the first proportional range is 0.55 to 0.65, and the second proportional range is 0.35 to 0.45.

[0055] In another implementation, the controller 60 uses a timer to control the switching of the motor 40 among the six phases. When there is uneven commutation, the controller 60 eliminates the uneven commutation by dynamically adjusting the timer count referenced during commutation. Specifically, the controller 60 can control the timer to start counting after the motor 40 enters each phase. When the timer increment reaches the corresponding timer count, the motor 40 is controlled to switch from the current phase to the next phase.

[0056] The first timer count corresponds to the rising commutation point. Taking the AC phase conduction stage as an example, the timer increment increases from 0 after entering this stage. When the first timer count is reached, the controller 60 controls the motor 40 to switch from AC phase conduction to BC phase conduction. The second timer count corresponds to the falling commutation point. Taking the BC phase conduction stage as an example, the timer increment increases from 0 after entering this stage. When the second timer count is reached, the controller 60 controls the motor 40 to switch from BC phase conduction to BA phase conduction. In some embodiments, after the controller 60 determines that the motor 40 has uneven commutation, in the following example, Figure 4a In the case where the duration of the rising phase is longer than the duration of the falling phase, the first timer count may be reduced, and / or the second timer count may be increased. In other embodiments, after the controller 60 determines that the motor 40 has uneven commutation, Figure 4b When the rising phase duration is shorter than the falling phase duration, the first timer count may be increased, and / or the second timer count may be decreased, so that the duration T of the AC phase conduction phase is u1 The duration of the BC phase conduction phase T d2 Gradually balance and eliminate uneven commutation.

[0057] It can be understood that the controller 60 dynamically adjusts the rising commutation point and / or the falling commutation point as only one of the means for controlling the motor 40 to eliminate uneven commutation. In some implementations, the controller 60 may eliminate the uneven commutation of the motor 40 without reflecting it in the control of the commutation point. It may be affected by the structure of the motor 40, the algorithm used by the controller 60 to control the motor 40, etc. In summary, the controller 60 can be configured to control the duration of each phase during the operation of the motor 40 and keep the duration of each phase basically equal, that is, the difference or ratio between the durations of each phase of the motor 40 is within the allowable deviation range.

[0058] The benefit of the present application lies in: detecting the duration of each phase of the motor and thereby determining whether the motor currently has uneven commutation, and then eliminating the uneven commutation phenomenon by dynamically adjusting the rising commutation point and / or the falling commutation point when the phenomenon exists, thereby avoiding problems such as misjudgment of stall protection caused by fluctuations in the duration of each phase when the power tool is overloaded, etc., ensuring that the motor in the power tool can always operate normally and smoothly, which is beneficial to improving tool efficiency and performance and optimizing user experience.

[0059] After experimental verification, for the same electric tool, when the reference time of the stall protection remains unchanged, its upper load limit was 7kg before the above-mentioned technical solution was adopted, while after adopting the solution of this application, its upper load limit was more than 8.5kg, and all aspects of the performance of the electric tool and its motor have been significantly improved.

[0060] Correspondingly, refer to Figure 5 The present application also provides a control method of an electric tool 100, which is applied to various types of electric tools 100 and may include:

[0061] 510, the detection device of the electric tool 100 detects the duration of each phase of the motor 40 of the electric tool 100; the duration of each phase of the motor 40 is the duration that the motor rotor is located in each electrical angle sector;

[0062] 520, the controller 60 of the electric tool 100 obtains the rising phase duration and the falling phase duration of the motor 40 from the phase durations of the motor 40, and determines whether there is uneven commutation in the motor 40 based on the rising phase duration and the falling phase duration;

[0063] 530, when there is uneven commutation in the motor 40, the controller 60 dynamically adjusts the rising commutation point and / or the falling commutation point of the motor 40 based on the relationship between the rising phase duration and the falling phase duration;

[0064] Among them, the floating phase voltage increases from low to high during the rising phase duration, and the floating phase voltage decreases from high to low during the falling phase duration.

[0065] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the above embodiments do not limit the present application in any form, and any technical solution obtained by equivalent replacement or equivalent transformation falls within the protection scope of the present application.

Claims

1. An electric tool comprising: Functional parts; A motor, used to drive the functional parts to operate; A power supply device, at least used to supply power to the motor; A controller, connected to the motor, for controlling the operation of the motor; The electric tool further comprises: a detection device connected to the motor and the controller, and configured to detect the duration of each phase of the motor; the duration of each phase of the motor is the duration of the motor rotor being located in each electrical angle sector; The controller is configured to: obtain the rising phase duration and the falling phase duration of the motor from the phase durations of each phase of the motor, and determine whether the motor has uneven commutation based on the rising phase duration and the falling phase duration; when the motor has uneven commutation, dynamically adjust the rising commutation point and / or the falling commutation point of the motor based on the size relationship between the rising phase duration and the falling phase duration; the floating phase voltage increases from low within the rising phase duration, and the floating phase voltage decreases from high within the falling phase duration.

2. The electric tool according to claim 1, wherein: The controller is configured to: determine that the motor has uneven commutation when the difference between the rising phase duration and the falling phase duration exceeds a preset difference threshold; or determine that the motor has uneven commutation when the ratio of the rising phase duration to the falling phase duration exceeds a preset ratio threshold.

3. The electric tool according to claim 1, wherein: The motor is a three-phase motor having six electrical angle sectors and corresponding six-phase durations, wherein the six-phase durations are the durations of alternating rising phases and falling phases.

4. The electric tool according to claim 1, wherein: The rising phase duration and the falling phase duration are the durations of two adjacent phases; or, the rising phase duration is the sum of the durations of three rising phases generated by one rotation of the motor rotor, and the falling phase duration is the sum of the durations of three falling phases generated by one rotation of the motor rotor.

5. The electric tool according to claim 1, wherein: The controller is configured to: adjust the first proportional point corresponding to the rising commutation point to change the triggering timing of the rising commutation point, and control the motor to switch from the current rising phase to the next phase when the floating phase voltage of the motor rises from the lowest point to the first proportional point; and / or adjust the second proportional point corresponding to the falling commutation point to change the triggering timing of the falling commutation point, and control the motor to switch from the current falling phase to the next phase when the floating phase voltage of the motor drops from the highest point to the second proportional point.

6. The electric tool according to claim 5, wherein: The controller is configured to: when uneven commutation occurs in the motor, if the duration of the rising phase is greater than the duration of the falling phase, reduce the first proportion point, and / or reduce the second proportion point.

7. The electric tool according to claim 5, wherein: The controller is configured to: when uneven commutation occurs in the motor, if the duration of the rising phase is shorter than the duration of the falling phase, increase the first proportion point, and / or increase the second proportion point.

8. The electric tool according to claim 5, wherein: The controller is configured to adjust the first proportion point within a preset first proportion range, and / or adjust the second proportion point within a preset second proportion range until the uneven commutation phenomenon of the motor is eliminated.

9. The electric tool according to claim 8, wherein: The first ratio ranges from 0.5 to 0.8; the second ratio ranges from 0.2 to 0.

5.

10. The electric tool according to claim 1, wherein: The controller is configured to: adjust the first timer count corresponding to the rising commutation point to change the triggering timing of the rising commutation point, and control the motor to switch to the next phase when the timer increment reaches the first timer count after the motor enters the rising phase; and / or adjust the second timer count corresponding to the falling commutation point to change the triggering timing of the falling commutation point, and control the motor to switch to the next phase when the timer increment reaches the second timer count after the motor enters the falling phase.

11. An electric tool comprising: Functional parts; A motor, used to drive the functional parts to operate; A power supply device, at least used to supply power to the motor; A controller, connected to the motor, for controlling the operation of the motor; Wherein, the controller is configured to: control the duration of each phase during the operation of the motor so that the duration of each phase of the motor remains basically equal; the duration of each phase of the motor is the duration that the motor rotor is located in each electrical angle sector.

12. A method for controlling an electric tool, wherein: The method comprises: The detection device of the electric tool detects the duration of each phase of the motor of the electric tool; the duration of each phase of the motor is the duration that the motor rotor is located in each electrical angle sector; The controller of the electric tool obtains the rising phase duration and the falling phase duration of the motor from the phase durations of each phase of the motor, and determines whether there is uneven commutation phenomenon in the motor based on the rising phase duration and the falling phase duration; In the case where the motor has uneven commutation, the controller dynamically adjusts the rising commutation point and / or the falling commutation point of the motor based on the magnitude relationship between the rising phase duration and the falling phase duration; The floating phase voltage increases from low to high during the rising phase duration, and the floating phase voltage decreases from high to low during the falling phase duration.

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