CN113922713A

CN113922713A - BLDC motor starting method with salient polarity, control device and electric tool

Info

Publication number: CN113922713A
Application number: CN202111145997.6A
Authority: CN
Inventors: 刘乐书; 周述宇; 韩若谷
Original assignee: Shenzhen H&T Intelligent Control Co Ltd
Current assignee: Shenzhen H&T Intelligent Control Co Ltd
Priority date: 2021-09-28
Filing date: 2021-09-28
Publication date: 2022-01-11

Abstract

The embodiment of the invention provides a BLDC motor starting method with saliency, a control device and an electric tool, wherein in the method, control signals are injected into the BLDC motor with the saliency at each potential angle in sequence, wherein the interval between two adjacent potential angles is 30 degrees; then, reading current signals of each potential angle when the motor injects voltage; then, determining an initial potential angle of the BLDC motor with the saliency according to each current signal, wherein the initial potential angle is used for indicating the initial position state of the BLDC motor with the saliency; finally, the BLDC motor having the saliency is started according to the initial potential angle. According to the method, control signals are injected into the BLDC motor with the saliency at the potential angles of 30 degrees at intervals, and the initial position of the BLDC motor with the saliency is determined according to the current of each potential angle, so that the motor is started.

Description

BLDC motor starting method with salient polarity, control device and electric tool

Technical Field

The embodiment of the invention relates to the technical field of a BLDC motor with saliency, in particular to a starting method, a control device and an electric tool of the BLDC motor with the saliency.

Background

The motor is an important component in a dragging system and plays a significant role in national economy. The use of the novel agricultural environment-friendly fire extinguishing agent almost permeates all walks of life and is an important guarantee for normal proceeding of industrial agriculture, national defense construction and people's life.

Currently, when a Brushless Direct Current (BLDC) motor is started, an initial position of the motor is usually determined, and then the motor is started according to the initial position. However, the existing starting method has low success probability and low anti-interference performance.

Disclosure of Invention

The embodiment of the invention aims to provide a BLDC motor starting method with salient polarity, a control device and an electric tool, which have high starting probability and strong anti-interference performance.

In a first aspect, one technical solution adopted in the embodiments of the present invention is: there is provided a method of starting a BLDC motor having a saliency, applied to a power tool including a BLDC motor having a saliency, the method including: injecting control signals into the BLDC motor at each potential angle in sequence, wherein the interval between two adjacent potential angles is 30 degrees, and the duty ratios of the control signals injected at each potential angle are the same; reading current signals of all potential angles of the BLDC motor in the control signal; determining an initial potential angle of the BLDC motor according to each current signal, wherein the initial potential angle is used for indicating an initial position state of the BLDC motor; and starting the BLDC motor according to the initial potential angle.

In some embodiments, said reading the current signal for each potential angle of said BLDC motor at said control signal comprises: and reading current signals of the buses of the BLDC motor at each potential angle at a preset time point of injecting the control signal every time.

In some embodiments, the power tool includes an inverter unit including a first phase upper bridge, a first phase lower bridge, a second phase upper bridge, a second phase lower bridge, a third phase upper bridge, and a third phase lower bridge, the injecting of the control signals to the BLDC motor at each potential angle in sequence, includes: in a first period, injecting a first control signal to the third phase upper bridge and controlling the second phase lower bridge to be conducted; in a second period, injecting a second control signal to the third phase upper bridge, and controlling the first phase lower bridge and the second phase lower bridge to be conducted; injecting a third control signal to the third phase upper bridge and controlling the first phase lower bridge to be conducted in a third period; in a fourth period, injecting a fourth control signal to the second phase upper bridge and the third phase upper bridge, and controlling the first phase lower bridge to be conducted; in a fifth period, injecting a fifth control signal to the second phase upper bridge and controlling the first phase lower bridge to be conducted; in a sixth period, injecting a sixth control signal to the second-phase upper bridge, and controlling the first-phase lower bridge and the third-phase lower bridge to be conducted; in a seventh period, injecting a seventh control signal to the second phase upper bridge and controlling the third phase lower bridge to be conducted; in an eighth period, injecting an eighth control signal to the first phase upper bridge and the second phase upper bridge, and controlling the third phase lower bridge to be conducted; in a ninth period, injecting a ninth control signal to the first phase upper bridge and controlling the third phase lower bridge to be conducted; in a tenth period, injecting a tenth control signal to the first-phase upper bridge, and controlling the second-phase lower bridge and the third-phase lower bridge to be conducted; in an eleventh period, injecting an eleventh control signal to the first phase upper bridge and controlling the second phase lower bridge to be conducted; and in a twelfth period, injecting a twelfth control signal to the third phase upper bridge and the first phase upper bridge, and controlling the second phase lower bridge to be conducted.

In some embodiments, said reading current signals for each potential angle of said BLDC motor at said control signal, and determining an initial potential angle of said BLDC motor based on each of said current signals, comprises: reading a first current, a second current, a third current, a fourth current, a fifth current, a sixth current, a seventh current, an eighth current, a ninth current, a tenth current, an eleventh current and a twelfth current of the bus at preset time points of the first cycle, the second cycle, the third cycle, the fourth cycle, the fifth cycle, the eighth cycle and the twelfth cycle, respectively; taking the maximum current value of the first current, the third current, the fifth current, the seventh current, the ninth current and the eleventh current as a first value, and taking a second large current value as a second value; taking a maximum current value of the second current, the fourth current, the sixth current, the eighth current, the tenth current, and the twelfth current as a third value; and obtaining an initial potential angle of the BLDC motor according to the first value, the second value and the third value.

In some embodiments, said deriving an initial potential angle of the BLDC motor from the first value, the second value, and the third value comprises: if the first value is the first current, the second value is the third current, and the third value is the second current, the initial potential angle of the BLDC motor is 0 ° -60 °; if the first value is a third current, the second value is a fifth current, and the third value is a fourth current, the initial potential angle of the BLDC motor is 60 ° -120 °; if the first value is a fifth current, the second value is a seventh current, and the third value is a sixth current, the initial potential angle of the BLDC motor is 120 ° -180 °; if the first value is a seventh current, the second value is a ninth current, and the third value is an eighth current, the initial potential angle of the BLDC motor is 180 ° -240 °; if the first value is a ninth current, the second value is an eleventh current, and the third value is a tenth current, the initial potential angle of the BLDC motor is 240 ° -300 °; if the first value is the eleventh current, the second value is the first current, and the third value is the twelfth current, the initial potential angle of the BLDC motor is 300 ° -360 °.

In some embodiments, said starting said BLDC motor according to said initial potential angle comprises: controlling the BLDC motor to work according to the initial potential angle; acquiring the reaction electromotive force of the BLDC motor, and if the correct reaction electromotive force is acquired, controlling the BLDC motor to change the phase according to the reaction electromotive force; acquiring the reaction electromotive force of the BLDC motor again after the BLDC motor is subjected to phase conversion; and when the reaction electromotive force of the BLDC motor is obtained for M times continuously, the BLDC motor is enabled to enter closed-loop control, wherein M is a positive integer greater than or equal to 2.

In some embodiments, said starting said BLDC motor according to said initial potential angle further comprises: starting a timer after the BLDC motor starts to work or after the BLDC motor changes the phase; when the timing time of the timer is reached, if the correct reaction electromotive force is not obtained, the BLDC motor is forced to change the phase; when the number of times of forcing the BLDC motor to change the phase reaches a preset number threshold, determining that the BLDC motor fails to start; when the number of times of forcing the BLDC motor to change the phase does not reach a preset number threshold, acquiring the reaction electromotive force of the BLDC motor; and if the reaction electromotive force is correct, controlling the BLDC motor to carry out phase change according to the reaction electromotive force, and acquiring the reaction electromotive force of the BLDC motor again.

In a second aspect, an embodiment of the present invention further provides a control device, where the control device includes: at least one processor; and a memory communicatively coupled to the at least one processor; wherein the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the BLDC motor starting method with saliency as claimed in any one of the first aspects.

In a third aspect, an embodiment of the present invention further provides an electric power tool, including: a BLDC motor having a saliency, an inverter unit and a control device as described in the second aspect; the inversion unit is connected with an external power supply through a bus, the inversion unit is in three-phase connection with the BLDC motor, and the control device is respectively connected with the inversion unit and the BLDC motor.

In a fourth aspect, embodiments of the present invention further provide a computer-readable storage medium, where computer-executable instructions are stored, and the computer-executable instructions are configured to cause a computer to perform the BLDC motor starting method with saliency as set forth in any one of the first aspect.

In a fifth aspect, the present invention also provides a computer program product, the computer program product comprising a computer program stored on a computer-readable storage medium, the computer program comprising program instructions which, when executed by a computer, cause the computer to perform the method of the first aspect.

Compared with the prior art, the invention has the beneficial effects that: different from the prior art, the embodiment of the invention provides a method for starting a BLDC motor with saliency, a control device and an electric tool, wherein in the method, control signals are injected into the BLDC motor with saliency at each potential angle in sequence, wherein an interval between two adjacent potential angles is 30 degrees; then, reading current signals of all potential angles of the BLDC motor with the salient polarity during signal control; then, determining an initial potential angle of the BLDC motor with the saliency according to each current signal, wherein the initial potential angle is used for indicating the initial position state of the BLDC motor with the saliency; finally, the BLDC motor having the saliency is started according to the initial potential angle. In the method, control signals are injected into the BLDC motor with the salient polarity at the potential angle of 30 degrees at intervals, 12 control signals with the same duty ratio are injected, the current signal during each control signal is read, the initial position of the BLDC motor is determined according to the 12 current signals, the accuracy of initial position identification is improved, the motor is started on the basis of accurately identifying the initial position, and the success rate of starting of the motor is improved.

Drawings

One or more embodiments are illustrated by the accompanying figures in the drawings that correspond thereto and are not to be construed as limiting the embodiments, wherein elements/modules and steps having the same reference numerals are represented by like elements/modules and steps, unless otherwise specified, and the drawings are not to scale.

Fig. 1 is a schematic diagram of an application environment of a BLDC motor starting method with saliency according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of an electric tool according to an embodiment of the present invention;

FIG. 3 is a schematic structural view of another power tool provided in an embodiment of the present invention;

FIG. 4 is a schematic structural diagram of another power tool provided in an embodiment of the present invention;

fig. 5 is a schematic structural diagram of a control device according to an embodiment of the present invention;

fig. 6 is a schematic flowchart of a BLDC motor starting method with saliency according to an embodiment of the present invention;

FIG. 7 is a schematic flowchart of step S120 in FIG. 6;

FIG. 8 is a schematic flow chart of step S110 in FIG. 6;

fig. 9 is a partial flowchart of a BLDC motor starting method with saliency according to an embodiment of the present invention;

FIG. 10 is a schematic flowchart of step S123 in FIG. 9;

FIG. 11 is a schematic flow chart of step S140 in FIG. 6;

fig. 12 is another schematic flow chart of step S140 in fig. 6.

Detailed Description

The present invention will be described in detail with reference to specific examples. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.

In order to facilitate an understanding of the present application, the present application is described in more detail below with reference to the accompanying drawings and specific embodiments. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description of the present application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed items.

It should be noted that, if not conflicted, the various features of the embodiments of the invention may be combined with each other within the scope of protection of the present application. In addition, although the functional blocks are divided in the device diagram, in some cases, the blocks may be divided differently from those in the device. Further, the terms "first," "second," and the like, as used herein, do not limit the data and the execution order, but merely distinguish the same items or similar items having substantially the same functions and actions.

Currently, a three-step starting method is commonly used in a starting method of a non-inductive BLDC motor. In the three-step start-up method: firstly, electrifying two fixed phases of the motor, and stopping the motor at a fixed position so as to position the motor; setting a phase change sequence according to set time, dragging the motor to operate, and observing the reaction electromotive force of the motor; and finally, after the reaction electromotive force of the motor is observed, the motor is switched to be driven by the reaction electromotive force, and the closed-loop control is switched from the open loop to the closed loop control. However, the positioning starting method and the starting torque are small, the motor can be started under the condition that the requirement of a fan and the like on the starting torque is not high, and when the motor is loaded, the success probability of starting the motor is not high.

Fig. 1 is a schematic diagram of an application environment of a BLDC motor starting method with saliency according to an embodiment of the present invention, where the application environment includes: a power tool 100 and an external power source 200, the power tool 100 including a BLDC motor 10 having a saliency, and an inverter unit 20. Wherein, the input end of the inverter unit 20 is connected to the external power source 200 through a bus, and the output end of the inverter unit 20 is three-phase connected to the BLDC motor 10 having a saliency. The power tool 100 may be a beauty instrument, a refrigerator, or any other device including a BLDC motor having a saliency.

It should be noted that the BLDC motor 10 having saliency and the BLDC motor referred to in the present invention are both BLDC motors having strong saliency, that is, such BLDC motors are generally fixed in position when stopped, and the stopped position is generally a position of a multiple of 30 ° in electrical angle. When starting such a BLDC motor, it is often necessary to locate the initial position of the BLDC motor, so that the motor can be started according to the initial position of the BLDC motor with saliency, and thus the motor can be controlled to work normally.

In order to improve the accuracy of positioning the BLDC motor with saliency, so that the BLDC motor with saliency can rapidly enter high-speed operation, the embodiments of the present invention provide a method, a control device, and an electric tool for starting the BLDC motor with saliency, wherein a control signal is injected into the BLDC motor with saliency at potential angles of 30 degrees each, and an initial position of the BLDC motor with saliency is determined according to a current of each potential angle, so as to start the motor according to the initial position of the BLDC motor with saliency, and the positioning starting method has high starting probability and strong anti-interference performance.

It should be noted that the BLDC motor starting method with saliency provided by the embodiment of the present invention is generally performed by the above-mentioned electric tool, and the control device provided by the embodiment of the present invention is generally disposed in the electric tool, and specifically, the embodiment of the present invention is further described below with reference to the accompanying drawings.

Referring to fig. 2, fig. 2 is a schematic structural diagram of an electric tool 100 according to an embodiment of the present invention, and as shown in fig. 2, the electric tool 100 includes: a BLDC motor 10 having a saliency, an inverter unit 20 and a control device 30. The inverter unit 20 is connected to an external power source 200 through a bus, the inverter unit 20 is three-phase connected to the BLDC motor 10 having a salient polarity, and the control device 30 is connected to the inverter unit 20 and the BLDC motor 10 having a salient polarity, respectively.

In some embodiments, referring to fig. 3, the inverter unit 20 includes a first phase upper bridge Q1, a first phase lower bridge Q2, a second phase upper bridge Q3, a second phase lower bridge Q4, a third phase upper bridge Q5, and a third phase lower bridge Q6. The first end of the first phase upper bridge Q1, the first end of the second phase upper bridge Q3 and the first end of the third phase upper bridge Q5 are connected with a positive pole VCC of the bus; the second end of the first phase upper bridge Q1 is connected with the first end of the first phase lower bridge Q2, the second end of the second phase upper bridge Q3 is connected with the first end of the second phase lower bridge Q4, the second end of the third phase upper bridge Q5 is connected with the first end of the third phase lower bridge Q6, the common connection end of the first phase upper bridge Q1 and the first phase lower bridge Q2, the common connection end of the second phase upper bridge Q3 and the second phase lower bridge Q4, and the common connection end of the third phase upper bridge Q5 and the third phase lower bridge Q6 are respectively connected with the BLDC motor 10 with the salient polarity in a three-phase manner; the second end of the first phase lower bridge Q2, the second end of the second phase lower bridge Q4 and the second end of the third phase lower bridge Q6 are connected to the ground in common; the control end of the first-phase upper bridge Q1, the control end of the first-phase upper bridge Q1 of the first-phase lower bridge Q2, the control end of the first-phase upper bridge Q1 of the second-phase upper bridge Q3, the control end of the first-phase upper bridge Q1 of the second-phase lower bridge Q4, the control end of the first-phase upper bridge Q1 of the third-phase upper bridge Q5 and the control end of the first-phase upper bridge Q1 of the third-phase lower bridge Q6 are respectively connected with the control device 30. Specifically, the first, second, and third phases may be U, V, and W phases, respectively connected to three-phase windings of the BLDC motor 10 having a saliency.

In some embodiments, referring to fig. 4, the power tool 100 further includes a current collecting unit 40, an input end of the current collecting unit 40 is connected to the negative bus, and an output end of the current collecting unit 40 is connected to the control device 30. Specifically, the input end of the current collection unit is connected with the common connection end of the second end of the first-phase lower bridge, the second end of the second-phase lower bridge and the second end of the third-phase lower bridge, the output end of the current collection unit is connected with the control device, and the current collection unit is used for collecting current signals of each potential angle of the BLDC motor during control signals and sending the current signals to the control device, so that the control device reads the current signals of each potential angle of the BLDC motor during control signals. For example, the current collecting unit may be an operational amplifier circuit, or any other suitable circuit structure in the prior art that can be used to collect current signals of each potential angle of the BLDC motor when controlling signals, and is not limited herein.

In some embodiments, with continued reference to fig. 4, the electric tool 100 further includes a reactive electromotive force collecting unit 50, wherein input ends of the reactive electromotive force collecting unit 50 are respectively connected to the three-phase windings of the BLDC motor 10 having the saliency, and an output end of the reactive electromotive force collecting unit 50 is connected to the control device 30, and the reactive electromotive force collecting unit is configured to collect the reactive electromotive force of the BLDC motor 10 having the saliency and send the reactive electromotive force to the control device 30 after the BLDC motor 10 having the saliency starts to operate, so that the control device 30 reads the reactive electromotive force of the BLDC motor 10 having the saliency.

Specifically, the reaction electromotive force acquisition unit may be three voltage division circuits formed by voltage division resistors, a first end of each voltage division circuit is connected to one phase winding of the BLDC motor, and a second end of each voltage division circuit is connected to the control device. It should be understood that the reactive electromotive force collecting unit may also be any other suitable circuit structure in the prior art that can be used to collect the reactive electromotive force of the BLDC motor with the salient polarity, and is not limited herein.

In some embodiments, the control device may be a general purpose processor, a Digital Signal Processor (DSP), an Application Specific Integrated Circuit (ASIC), a Field Programmable Gate Array (FPGA), a single chip, an arm (acorn RISC machine) or other programmable logic device, discrete gate or transistor logic, discrete hardware components, or any combination of these components. Also, the control device may be any conventional processor, controller, microcontroller, or state machine. The control device may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP, and/or any other such configuration.

Referring to fig. 5, fig. 5 is a schematic structural diagram of a control device according to an embodiment of the present invention. The control device comprises at least one processor and a memory communicatively connected with the at least one processor, wherein one processor is taken as an example in fig. 5.

The memory 32 stores instructions executable by the at least one processor 31, the instructions being executable by the at least one processor 31 to enable the at least one processor 31 to perform the BLDC motor starting method with saliency as described in fig. 2-6 below. The processor 31 and the memory 32 may be connected by a bus or other means, and fig. 5 illustrates the connection by a bus as an example. The control means may be the control means shown in figure 2.

The memory 32, which is a non-volatile computer-readable storage medium, may be used to store non-volatile software programs, non-volatile computer-executable programs, and modules, such as program instructions/modules corresponding to the BLDC motor starting method with saliency in the embodiment of the present application. The processor 31 executes various functional applications of the control device and data processing by running a nonvolatile software program, instructions, and modules stored in the memory 32, that is, implements the BLDC motor starting method having a saliency in the following method embodiment.

The memory 32 may include a storage program area and a storage data area, wherein the storage program area may store an operating system, an application program required for at least one function; the storage data area may store data created according to use of the control device, and the like. Further, the memory 32 may include high speed random access memory, and may also include non-volatile memory, such as at least one magnetic disk storage device, flash memory device, or other non-volatile solid state storage device. In some embodiments, the memory 32 may optionally include memory located remotely from the processor 31, and these remote memories may be connected to the control device via a network. Examples of such networks include, but are not limited to, the internet, intranets, local area networks, mobile communication networks, and combinations thereof.

The one or more modules are stored in the memory 32 and, when executed by the one or more processors 31, perform a BLDC motor starting method with saliency in any of the method embodiments described below, e.g., performing the method steps of fig. 6-12 described below.

The product can execute the method provided by the embodiment of the application, and has the corresponding functional modules and beneficial effects of the execution method. For technical details that are not described in detail in this embodiment, reference may be made to the methods provided in the embodiments of the present application.

Referring to fig. 6, a flow chart of a BLDC motor starting method with saliency according to an embodiment of the present invention is shown, wherein the BLDC motor starting method with saliency can be executed by the control device in fig. 2-5, and the method includes, but is not limited to, the following steps:

step S110: injecting control signals into the BLDC motor at each potential angle in sequence, wherein the interval between two adjacent potential angles is 30 degrees;

since the BLDC motor having saliency is strong in saliency, its initial position is usually a position of a multiple of 30 ° in electrical angle. To determine an initial position of the BLDC motor having saliency, after the BLDC motor triggers a start condition, a control signal is injected to the BLDC motor when the motor is at a potential angle of 30 degrees per interval, respectively. Specifically, after the BLDC motor triggers the start condition, a control signal is injected into the BLDC motor to rotate the potential angle of the BLDC motor from the initial potential angle to the next potential angle, and when the potential angle of the BLDC motor rotates to the next potential angle, another control signal is injected into the BLDC motor again, and the process is repeated until 12 control signals are periodically injected into the BLDC motor.

In this embodiment, the duty ratios of the control signals injected at each potential angle are the same.

Step S120: reading current signals of all potential angles of the BLDC motor in the control signal;

specifically, a current signal of a potential angle of the BLDC motor is obtained by the current collecting unit each time the control signal is injected.

In some embodiments, referring to fig. 7, the step S120 includes:

step S121: reading current signals of the BLDC motor at buses of all potential angles at a preset time point of injecting the control signal every time;

specifically, the preset time point is a fixed time point of each injection period, and the injection period is a time for injecting the control signal once. Then, when 12 control signals are injected into the BLDC motor cycle, the current signal of the bus of the BLDC motor is read at a fixed time point of each injection cycle, thereby obtaining 12 current signals. By sampling at a fixed time point of each injection period, the obtained current signals of the buses can be ensured to be comparable. The fixed time point can be a time point close to the termination time in each injection period, for example, a time point which is advanced by a few μ s when each injection period is about to end, so that the collected current signal can be ensured to be a bus current signal of a potential angle when the control signal is about to be completely injected, and the accuracy of the current signal is improved.

Step S130: determining an initial potential angle of the BLDC motor according to each current signal, wherein the initial potential angle is used for indicating an initial position state of the BLDC motor;

by injecting a control signal into the BLDC motor at a potential angle of 30 degrees, 12 current signals of 30 degrees can be obtained, and since the 12 current signals have a certain relationship with the initial potential angle of the BLDC motor, the initial potential angle of the BLDC motor can be obtained from the 12 current signals.

Step S140: and starting the BLDC motor according to the initial potential angle.

Specifically, after the initial potential angle of the BLDC motor is obtained, the BLDC motor can be controlled to start according to the initial potential angle of the BLDC motor, so that the BLDC motor can be started.

In the method for starting the BLDC motor provided in the embodiment of the present invention, the control signal is injected into the BLDC motor at the potential angle every 30 degrees, and the initial position of the BLDC motor is determined according to the current of each potential angle, that is, the control signal is injected into the BLDC motor with the saliency at the potential angle every 30 degrees, and the accuracy of initial position identification is improved by injecting 12 control signals with the same duty ratio and reading the current signal during each control signal, and further determining the initial position of the BLDC motor according to the 12 current signals, so that the motor is started on the basis of accurately identifying the initial position, and the success rate of starting the motor is improved.

In some embodiments, the power tool includes an inverter unit, the inverter unit includes a first phase upper bridge, a first phase lower bridge, a second phase upper bridge, a second phase lower bridge, a third phase upper bridge, and a third phase lower bridge, and connection relationships among the bridges in the inverter unit may refer to the connection manner described above, which is not described herein again, and refer to fig. 8, where step S110 includes:

step S111: in a first period, injecting a first control signal to the third phase upper bridge and controlling the second phase lower bridge to be conducted;

step S112: in a second period, injecting a second control signal to the third phase upper bridge, and controlling the first phase lower bridge and the second phase lower bridge to be conducted;

step S113: injecting a third control signal to the third phase upper bridge and controlling the first phase lower bridge to be conducted in a third period;

step S114: in a fourth period, injecting a fourth control signal to the second phase upper bridge and the third phase upper bridge, and controlling the first phase lower bridge to be conducted;

step S115: in a fifth period, injecting a fifth control signal to the second phase upper bridge and controlling the first phase lower bridge to be conducted;

step S116: in a sixth period, injecting a sixth control signal to the second-phase upper bridge, and controlling the first-phase lower bridge and the third-phase lower bridge to be conducted;

step S117: in a seventh period, injecting a seventh control signal to the second phase upper bridge and controlling the third phase lower bridge to be conducted;

step S118: in an eighth period, injecting an eighth control signal to the first phase upper bridge and the second phase upper bridge, and controlling the third phase lower bridge to be conducted;

step S119: in a ninth period, injecting a ninth control signal to the first phase upper bridge and controlling the third phase lower bridge to be conducted;

step S1110: in a tenth period, injecting a tenth control signal to the first-phase upper bridge, and controlling the second-phase lower bridge and the third-phase lower bridge to be conducted;

step S1111: in an eleventh period, injecting an eleventh control signal to the first phase upper bridge and controlling the second phase lower bridge to be conducted;

step S1112: and in a twelfth period, injecting a twelfth control signal to the third phase upper bridge and the first phase upper bridge, and controlling the second phase lower bridge to be conducted.

Specifically, the first-phase upper bridge is a U-phase upper bridge, the first-phase lower bridge is a U-phase lower bridge, the second-phase upper bridge is a V-phase upper bridge, the second-phase lower bridge is a V-phase lower bridge, the third-phase upper bridge is a W-phase upper bridge, the third-phase lower bridge is a W-phase lower bridge, and each control signal is a PWM signal. Then, after the BLDC motor triggers the start condition, the electrical angle at the start time of the BLDC motor is the initial potential angle θ; then, in a first period, injecting a first PWM signal to the W-phase upper bridge and controlling the V-phase lower bridge to be conducted to enable the BLDC motor to rotate 30 degrees, wherein at the moment, the electrical angle of the BLDC motor is theta +30 degrees; in a second period, injecting a second PWM signal to the W-phase upper bridge, and controlling the conduction of the U-phase lower bridge and the V-phase lower bridge to enable the BLDC motor to rotate 30 degrees, wherein the electrical angle of the BLDC motor is theta +60 degrees; in a third period, injecting a third PWM signal to the W-phase upper bridge, and controlling the conduction of the U-phase lower bridge to enable the BLDC motor to rotate 30 degrees, wherein the electrical angle of the BLDC motor is theta +90 degrees; in a fourth period, injecting a fourth PWM signal to the V-phase upper bridge and the W-phase upper bridge, and controlling the conduction of the U-phase lower bridge to enable the BLDC motor to rotate 30 degrees, wherein the electrical angle of the BLDC motor is theta +120 degrees; in a fifth period, injecting a fifth PWM signal to the V-phase upper bridge, and controlling the conduction of the U-phase lower bridge to enable the BLDC motor to rotate 30 degrees, wherein at the moment, the electrical angle of the BLDC motor is theta +150 degrees; in a sixth period, injecting a sixth PWM signal to the V-phase upper bridge, and controlling the conduction of the U-phase lower bridge and the W-phase lower bridge to enable the BLDC motor to rotate 30 degrees, wherein the electrical angle of the BLDC motor is theta +180 degrees; in a seventh period, injecting a seventh PWM signal to the V-phase upper bridge, and controlling the W-phase lower bridge to be conducted, so that the BLDC motor rotates by 30 degrees, and at the moment, the electrical angle of the BLDC motor is theta +210 degrees; injecting an eighth PWM signal to the U-phase upper bridge and the V-phase upper bridge in an eighth period, and controlling the conduction of the W-phase lower bridge to enable the BLDC motor to rotate 30 degrees, wherein the electrical angle of the BLDC motor is theta +240 degrees; in a ninth period, injecting a ninth PWM signal to the U-phase upper bridge, and controlling the W-phase lower bridge to be conducted, so that the BLDC motor rotates 30 degrees, and at the moment, the electrical angle of the BLDC motor is theta +270 degrees; in a tenth period, injecting a tenth PWM signal to the U-phase upper bridge, and controlling the conduction of the V-phase lower bridge and the W-phase lower bridge to enable the BLDC motor to rotate 30 degrees, wherein at the moment, the electrical angle of the BLDC motor is theta +300 degrees; in an eleventh period, injecting an eleventh PWM signal to the U-phase upper bridge, and controlling the V-phase lower bridge to be conducted, so that the BLDC motor rotates by 30 degrees, and at the moment, the electrical angle of the BLDC motor is theta +330 degrees; and in a twelfth period, injecting a twelfth PWM signal to the W-phase upper bridge and the U-phase upper bridge, and controlling the V-phase lower bridge to be conducted, so that the BLDC motor rotates by 30 degrees, and at the moment, the electrical angle of the BLDC motor is theta +360 degrees.

By means of the mode of periodically injecting the PWM signals, the BLDC motor can be ensured to inject the control signals from the initial potential angle at the potential angle of 30 degrees.

In some embodiments, referring to fig. 9, the reading the current signals of the BLDC motor at the respective potential angles in the control signal, and determining the initial potential angle of the BLDC motor according to the current signals includes:

step S121: reading a first current, a second current, a third current, a fourth current, a fifth current, a sixth current, a seventh current, an eighth current, a ninth current, a tenth current, an eleventh current and a twelfth current of the bus at preset time points of the first cycle, the second cycle, the third cycle, the fourth cycle, the fifth cycle, the eighth cycle and the twelfth cycle, respectively;

step S122: taking the maximum current value of the first current, the third current, the fifth current, the seventh current, the ninth current and the eleventh current as a first value, and taking a second large current value as a second value; taking a maximum current value of the second current, the fourth current, the sixth current, the eighth current, the tenth current, and the twelfth current as a third value;

step S123: and obtaining an initial potential angle of the BLDC motor according to the first value, the second value and the third value.

Specifically, at a fixed point in time for each injection cycle to acquire current, then 12 current signals may be acquired. Then, putting the first current, the third current, the fifth current, the seventh current, the ninth current and the eleventh current into a first array, and putting the second current, the fourth current, the sixth current, the eighth current, the tenth current and the twelfth current into a second array; then, according to the magnitude of each current, obtaining that the maximum current value in the first array is a first value, the second large current value in the first array is a second value, and the maximum current value in the second array is a third value; since the initial position in the BLDC motor has a certain correspondence with the first value, the second value, and the third value, the initial potential angle of the BLDC motor can be obtained according to the first value, the second value, and the third value.

Specifically, in some embodiments, referring to fig. 10, the step S123 includes:

step S1231: if the first value is the first current, the second value is the third current, and the third value is the second current, the initial potential angle of the BLDC motor is 0 ° -60 °;

step S1232: if the first value is a third current, the second value is a fifth current, and the third value is a fourth current, the initial potential angle of the BLDC motor is 60 ° -120 °;

step S1233: if the first value is a fifth current, the second value is a seventh current, and the third value is a sixth current, the initial potential angle of the BLDC motor is 120 ° -180 °;

step S1234: if the first value is a seventh current, the second value is a ninth current, and the third value is an eighth current, the initial potential angle of the BLDC motor is 180 ° -240 °;

step S1235: if the first value is a ninth current, the second value is an eleventh current, and the third value is a tenth current, the initial potential angle of the BLDC motor is 240 ° -300 °;

step S1236: if the first value is the eleventh current, the second value is the first current, and the third value is the twelfth current, the initial potential angle of the BLDC motor is 300 ° -360 °.

For example, if the first value is a current value of the first current, the second value is a current value of the third current, and the third value is a current value of the second current, the initial potential angle of the BLDC motor may be determined to be 0 ° to 60 °, and so on.

In some embodiments, referring to fig. 11, the step S140 includes:

step S141: controlling the BLDC motor to work according to the initial potential angle;

step S142: acquiring the reaction electromotive force of the BLDC motor, and if the correct reaction electromotive force is acquired, controlling the BLDC motor to change the phase according to the reaction electromotive force;

step S143: acquiring the reaction electromotive force of the BLDC motor again after the BLDC motor is subjected to phase conversion;

step S144: and when the correct reaction electromotive force is obtained for M times continuously, enabling the BLDC motor to enter closed-loop control, wherein M is a positive integer greater than or equal to 2.

Specifically, after the initial potential angle of the BLDC motor is obtained according to the above steps, the BLDC motor may be controlled to operate according to the initial potential angle; then, the reaction electromotive force of the BLDC motor is obtained through a reaction electromotive force acquisition unit in combination with an enable multi-selection filtering algorithm; if the correct reaction electromotive force is obtained, controlling the BLDC motor to carry out phase commutation according to the reaction electromotive force; and after the BLDC motor is subjected to phase change, acquiring the reaction electromotive force again through the reaction electromotive force acquisition unit, obtaining the reaction electromotive force of the BLDC motor through an enabling multi-selection filtering algorithm, continuously judging whether the reaction electromotive force is correct, if so, continuously controlling the BLDC motor to perform phase change according to the reaction electromotive force, and circulating the steps until the correct reaction electromotive force is obtained for 2 times continuously, and controlling the BLDC motor to enter closed-loop control work. By the mode, the problems of position commutation errors and software execution logic of the BLDC motor are solved, and the safety and reliability of the BLDC motor in high-speed operation are improved. In practical applications, the number of M can be freely set, and is not limited to the limitation in this embodiment.

In some embodiments, referring to fig. 12, the step S140 further includes:

step S145: starting a timer after the BLDC motor starts to work or after the BLDC motor changes the phase;

step S146: when the timing time of the timer is reached, if the correct reaction electromotive force is not obtained, the BLDC motor is forced to change the phase;

step S147: when the number of times of forcing the BLDC motor to change the phase reaches a preset number threshold, determining that the BLDC motor fails to start;

step S148: when the number of times of forcing the BLDC motor to change the phase does not reach a preset number threshold, acquiring the reaction electromotive force of the BLDC motor;

step S149: and if the reaction electromotive force is correct, controlling the BLDC motor to carry out phase change according to the reaction electromotive force, and acquiring the reaction electromotive force of the BLDC motor again.

Specifically, after the initial potential angle of the BLDC motor is obtained according to the above steps, the BLDC motor may be controlled to operate and the interrupt time of the timer may be set according to the initial potential angle; and then, obtaining the reaction electromotive force of the BLDC motor by a reaction electromotive force acquisition unit and combining with an enable majority filter algorithm.

And if the correct reaction electromotive force is obtained, controlling the BLDC motor to carry out phase change according to the reaction electromotive force, and re-driving the timer to obtain the reaction electromotive force again after the phase change. If the correct reaction electromotive force is not obtained when the interruption time of the timer is reached, controlling the BLDC motor to forcibly change the phase and re-driving the timer; at this time, if the number of times of the forced commutation is greater than the set threshold number of times, it is determined that the BLDC motor fails to start, and if the number of times of the forced commutation is less than or equal to the set threshold number of times, the reaction electromotive force of the BLDC motor is newly acquired.

Secondly, whether the obtained reaction electromotive force is correct after the phase commutation is continued, if the correct reaction electromotive force is obtained, the BLDC motor is continuously controlled according to the reaction electromotive force to carry out the phase commutation, the timer is driven again, and the reaction electromotive force is obtained again after the phase commutation; if the correct reaction electromotive force is not obtained when the interruption time of the timer is reached, controlling the BLDC motor to forcibly change the phase and re-driving the timer; at this time, if the number of times of the forced commutation is greater than the set threshold number of times, it is determined that the BLDC motor fails to start, and if the number of times of the forced commutation is less than or equal to the set threshold number of times, the reaction electromotive force of the BLDC motor is newly acquired.

And circulating in this way until the BLDC motor is controlled to enter closed-loop control work after the correct reaction electromotive force is obtained for M times continuously, or until the BLDC motor is determined to fail to start.

Therefore, in the motor starting method provided by the invention, the initial position of the motor is judged by injecting pulses, the motor is driven, the timer is started, the reaction electromotive force is used for commutation when a correct reaction electromotive force signal exists, the timer is used for forced commutation when the correct reaction electromotive force signal does not exist, the correct reaction electromotive force signal can be detected by generally 2-3 pulses of forced commutation, the position commutation error of the BLDC motor with the salient polarity is further solved by the timer and the forced commutation, and the safety and reliability of the BLDC motor with the salient polarity during high-speed operation are improved.

Embodiments of the present application also provide a non-transitory computer-readable storage medium storing computer-executable instructions for execution by one or more processors, e.g., to perform the method steps of fig. 6-12 described above.

Embodiments also provide a computer program product comprising a computer program stored on a non-volatile computer-readable storage medium, the computer program comprising program instructions which, when executed by a computer, cause the computer to perform the BLDC motor starting method with saliency, in any of the method embodiments described above, for example, to perform the method steps of fig. 6 to 12 described above.

The embodiment of the invention provides a BLDC motor starting method with saliency, a control device and an electric tool, wherein in the method, control signals are injected into the BLDC motor with the saliency at each potential angle in sequence, wherein the interval between two adjacent potential angles is 30 degrees; then, reading current signals of all potential angles of the BLDC motor with the salient polarity during signal control; then, determining an initial potential angle of the BLDC motor with the saliency according to each current signal, wherein the initial potential angle is used for indicating the initial position state of the BLDC motor with the saliency; finally, the BLDC motor having the saliency is started according to the initial potential angle. According to the method, control signals are injected into the BLDC motor with the saliency at the potential angles of 30 degrees at intervals, and the initial position of the BLDC motor with the saliency is determined according to the current of each potential angle, so that the motor is started.

It should be noted that the above-described device embodiments are merely illustrative, where the units described as separate parts may or may not be physically separate, and the parts displayed as units may or may not be physical units, may be located in one place, or may be distributed on multiple network units. Some or all of the modules may be selected according to actual needs to achieve the purpose of the solution of the present embodiment.

Through the above description of the embodiments, those skilled in the art will clearly understand that each embodiment can be implemented by software plus a general hardware platform, and certainly can also be implemented by hardware. Based on such understanding, the above technical solutions substantially or otherwise contributing to the related art may be embodied in the form of a software product, which may be stored in a computer-readable storage medium, such as ROM/RAM, magnetic disk, optical disk, etc., and includes a plurality of instructions for executing the method according to each embodiment or some parts of the embodiments by at least one computer device (which may be a personal computer, a server, or a network device, etc.).

Finally, it should be noted that: the above examples are only intended to illustrate the technical solution of the present invention, but not to limit it; within the idea of the invention, also technical features in the above embodiments or in different embodiments may be combined, steps may be implemented in any order, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method of starting a BLDC motor having saliency, applied to a power tool comprising a BLDC motor having saliency, said method comprising:

injecting control signals into the BLDC motor at each potential angle in sequence, wherein the interval between two adjacent potential angles is 30 degrees, and the duty ratios of the control signals injected at each potential angle are the same;

reading current signals of all potential angles of the BLDC motor in the control signal;

determining an initial potential angle of the BLDC motor according to each current signal, wherein the initial potential angle is used for indicating an initial position state of the BLDC motor;

and starting the BLDC motor according to the initial potential angle.

2. The method of claim 1, wherein reading the current signal for each potential angle of the BLDC motor in the control signal comprises:

and reading current signals of the buses of the BLDC motor at each potential angle at a preset time point of injecting the control signal every time.

3. The method of claim 2, wherein the power tool comprises an inverter unit, the inverter unit comprises a first phase upper bridge, a first phase lower bridge, a second phase upper bridge, a second phase lower bridge, a third phase upper bridge and a third phase lower bridge, and the injecting the control signal to the BLDC motor at each phase angle in sequence comprises:

in a first period, injecting a first control signal to the third phase upper bridge and controlling the second phase lower bridge to be conducted;

in a second period, injecting a second control signal to the third phase upper bridge, and controlling the first phase lower bridge and the second phase lower bridge to be conducted;

injecting a third control signal to the third phase upper bridge and controlling the first phase lower bridge to be conducted in a third period;

in a fourth period, injecting a fourth control signal to the second phase upper bridge and the third phase upper bridge, and controlling the first phase lower bridge to be conducted;

in a fifth period, injecting a fifth control signal to the second phase upper bridge and controlling the first phase lower bridge to be conducted;

in a sixth period, injecting a sixth control signal to the second-phase upper bridge, and controlling the first-phase lower bridge and the third-phase lower bridge to be conducted;

in a seventh period, injecting a seventh control signal to the second phase upper bridge and controlling the third phase lower bridge to be conducted;

in an eighth period, injecting an eighth control signal to the first phase upper bridge and the second phase upper bridge, and controlling the third phase lower bridge to be conducted;

in a ninth period, injecting a ninth control signal to the first phase upper bridge and controlling the third phase lower bridge to be conducted;

in a tenth period, injecting a tenth control signal to the first-phase upper bridge, and controlling the second-phase lower bridge and the third-phase lower bridge to be conducted;

in an eleventh period, injecting an eleventh control signal to the first phase upper bridge and controlling the second phase lower bridge to be conducted;

and in a twelfth period, injecting a twelfth control signal to the third phase upper bridge and the first phase upper bridge, and controlling the second phase lower bridge to be conducted.

4. The method as claimed in claim 3, wherein the reading of the current signals of the BLDC motor at the respective potential angles in the control signal, and the determining of the initial potential angle of the BLDC motor from the respective current signals, comprises:

reading a first current, a second current, a third current, a fourth current, a fifth current, a sixth current, a seventh current, an eighth current, a ninth current, a tenth current, an eleventh current and a twelfth current of the bus at preset time points of the first cycle, the second cycle, the third cycle, the fourth cycle, the fifth cycle, the eighth cycle and the twelfth cycle, respectively;

taking the maximum current value of the first current, the third current, the fifth current, the seventh current, the ninth current and the eleventh current as a first value, and taking a second large current value as a second value; taking a maximum current value of the second current, the fourth current, the sixth current, the eighth current, the tenth current, and the twelfth current as a third value;

and obtaining an initial potential angle of the BLDC motor according to the first value, the second value and the third value.

5. The method of starting a BLDC motor having saliency of claim 4, wherein said deriving an initial potential angle of said BLDC motor from said first value, said second value and said third value comprises:

if the first value is the first current, the second value is the third current, and the third value is the second current, the initial potential angle of the BLDC motor is 0 ° -60 °;

if the first value is a third current, the second value is a fifth current, and the third value is a fourth current, the initial potential angle of the BLDC motor is 60 ° -120 °;

if the first value is a fifth current, the second value is a seventh current, and the third value is a sixth current, the initial potential angle of the BLDC motor is 120 ° -180 °;

if the first value is a seventh current, the second value is a ninth current, and the third value is an eighth current, the initial potential angle of the BLDC motor is 180 ° -240 °;

if the first value is a ninth current, the second value is an eleventh current, and the third value is a tenth current, the initial potential angle of the BLDC motor is 240 ° -300 °;

if the first value is the eleventh current, the second value is the first current, and the third value is the twelfth current, the initial potential angle of the BLDC motor is 300 ° -360 °.

6. The method of starting a BLDC motor having saliency as recited in any one of claims 1-5, wherein said starting said BLDC motor according to said initial potential angle comprises:

controlling the BLDC motor to work according to the initial potential angle;

acquiring the reaction electromotive force of the BLDC motor, and if the correct reaction electromotive force is acquired, controlling the BLDC motor to change the phase according to the reaction electromotive force;

acquiring the reaction electromotive force of the BLDC motor again after the BLDC motor is subjected to phase conversion;

and when the correct reaction electromotive force is obtained for M times continuously, enabling the BLDC motor to enter closed-loop control, wherein M is a positive integer greater than or equal to 2.

7. The method of starting a BLDC motor having a saliency as recited in claim 6, wherein said starting said BLDC motor according to said initial potential angle further comprises:

starting a timer after the BLDC motor starts to work or after the BLDC motor changes the phase;

when the timing time of the timer is reached, if the correct reaction electromotive force is not obtained, the BLDC motor is forced to change the phase;

when the number of times of forcing the BLDC motor to change the phase reaches a preset number threshold, determining that the BLDC motor fails to start;

when the number of times of forcing the BLDC motor to change the phase does not reach a preset number threshold, acquiring the reaction electromotive force of the BLDC motor;

and if the reaction electromotive force is correct, controlling the BLDC motor to carry out phase change according to the reaction electromotive force, and acquiring the reaction electromotive force of the BLDC motor again.

8. A control device, characterized in that the control device comprises:

at least one processor; and the number of the first and second groups,

a memory communicatively coupled to the at least one processor; wherein the content of the first and second substances,

the memory stores instructions executable by the at least one processor to enable the at least one processor to perform the BLDC motor starting method with saliency as claimed in any one of claims 1-7.

9. A power tool, characterized in that the power tool comprises: a BLDC motor having a saliency, an inverter unit and a control device according to claim 8;

the inversion unit is connected with an external power supply through a bus, the inversion unit is in three-phase connection with the BLDC motor, and the control device is respectively connected with the inversion unit and the BLDC motor.

10. A computer-readable storage medium storing computer-executable instructions for causing a computer to perform the BLDC motor starting method having saliency as recited in any one of claims 1-7.