CN112398381B

CN112398381B - Stopping method and control method of brushless direct current motor, motor controller and electric device

Info

Publication number: CN112398381B
Application number: CN201910760513.5A
Authority: CN
Inventors: 张毅鸣; 支东祥; 付子鑫; 张俊民
Original assignee: United Automotive Electronic Systems Co Ltd
Current assignee: United Automotive Electronic Systems Co Ltd
Priority date: 2019-08-16
Filing date: 2019-08-16
Publication date: 2022-07-19
Anticipated expiration: 2039-08-16
Also published as: CN112398381A

Abstract

The invention provides a halt method and a control method of a brushless direct current motor, a motor controller and an electric device, and further provides a computer readable storage medium. According to the technical scheme, a rotor post-positioning control technology can be added at the motor stopping stage, so that the motor can realize the function of rotor pre-positioning when the motor is stopped, the initial position of the motor rotor is predetermined for the next motor starting, the starting time of the next motor is shortened, the starting response time is optimized, the problem that the rotor generates simple harmonic vibration in the next motor starting process can be avoided, the starting current is reduced, and the problems that the existing brushless direct current motor without the position sensor is long in starting time and unreliable in starting are solved finally.

Description

Stopping method and control method of brushless direct current motor, motor controller and electric device

Technical Field

The invention relates to the technical field of motor control, in particular to a halt method and a control method of a brushless direct current motor, a motor controller, an electric device and a computer readable storage medium.

Background

The Brushless DC Motor without position sensor (BLDC, may be referred to as Motor for short) has advantages of mainly omitting excitation device and position sensor, simplifying Motor structure, reducing Motor weight, reducing manufacturing cost, having characteristics of high reliability, high efficiency and excellent speed regulation performance, etc., and having obvious advantages in reducing loss, saving energy, etc., and thus has become an important development direction of novel motors, and is widely applied to household appliances (such as air conditioner, hair dryer, bladeless fan washing machine, refrigerator, dust collector, etc.), office equipment (such as scanner, copier, printer, paper shredder, etc.), industrial automation (such as industrial sewing machine, textile machinery, electric vehicle, machine tool, robot, elevator, automatic door control system, etc.), aerospace (such as high-speed turntable, gyro Motor, simulation, etc.) Inertial navigation test equipment), and the like.

Referring to fig. 1, fig. 1 is a schematic structural diagram of a brushless dc motor without a position sensor. The structure of the brushless DC motor without the position sensor can be divided into a stator 1 and a rotor 2, wherein the stator 1 mainly comprises an iron core 11 and

stator windings

12A, 12B and 12C formed by coils wound on the iron core 11, the

stator windings

12A, 12B and 12C form A, B, C three-phase windings of the motor, leading-out wires (not shown) of the

stator windings

12A, 12B and 12C can be connected into a star-shaped structure and a triangular structure, and the rotor 2 mainly comprises a permanent magnet 22 mounted on a central rotating shaft 21. When direct current is conducted between any two phases of stator windings of the motor, magnetic field force (namely electromagnetic force) in a fixed direction is generated on the stator side, the rotor 2 is attracted to be aligned with the magnetic field, and the purpose of driving the rotor 2 to rotate is achieved.

The existing brushless direct current motor without a position sensor is usually driven by square waves, a back electromotive force zero crossing point method is judged at the phase change moment based on the three-phase end voltage sampling of the motor, and the back electromotive force zero crossing point detection method requires that the motor reaches a certain rotating speed, so that a starting stage of the motor is required when the motor reaches the certain rotating speed. The existing brushless dc motor without a position sensor usually adopts a three-stage starting scheme, that is, the starting of the existing brushless dc motor without a position sensor needs to go through three stages of rotor pre-positioning, acceleration and operation state switching in sequence. Fig. 2 is a three-stage starting control schematic diagram of the brushless dc motor control without the position sensor. Fig. 3 shows the trend of the rotation speed of the rotor 2 in each stage of the three-stage start of the sensorless brushless dc motor control. Referring to fig. 1 to fig. 3, the "three-stage" start-up scheme is as follows:

the first phase S101 is a rotor pre-positioning phase for determining the initial position of the rotor 2 of the electrical machine, so that the rotor 2 can be started from a fixed position each time when stationary. Under the condition of light load, the low-power brushless direct current motor generally adopts a positioning mode of a magnetic braking rotor, namely, by conducting any two-phase winding of the motor, the magnetic flux formed in the motor can forcibly attract the rotor of the motor to the magnetic flux direction of the motor within a certain time, wherein the electrifying time and the PWM duty ratio on any two-phase winding can be calibrated.

The second stage S102 is an acceleration stage in which the applied voltage or the phase-change signal of the motor is artificially changed to gradually increase the rotation speed of the motor from a standstill state. After the rotor 2 is pre-positioned successfully, the applied voltage and the phase change signal of the motor must be manually changed to drive the motor to do accelerated motion, so that the accelerated speed is accelerated to a speed at which the strength of the back electromotive force can be used for detecting the zero crossing point requirement. In general, in practical applications, an acceleration curve needs to be set according to specific motor characteristics and loads to control the switching frequency and the PWM duty ratio of the commutation signal.

The third stage S103 is an operation state switching stage, that is, after the motor reaches the required rotation speed in the acceleration stage, the acceleration stage is switched to a normal operation stage of the motor, and the normal operation stage of the motor refers to determining a phase change time by detecting a zero crossing point of the back electromotive force. When the motor reaches a certain rotating speed through an acceleration stage, the back electromotive force signal can be accurately detected, and a driving mode of motor phase change is triggered by judging a characteristic signal point (called a zero crossing point) of the motor to replace an artificially set phase change frequency.

In the above-mentioned "three-stage" start control method of the conventional brushless dc motor without position sensor, when the rotor pre-positioning technique is adopted in the first stage, it is assumed that the B-phase winding on the stator side is selected to be conducted with the power supply and the C-phase winding (i.e., to be conducted with the B-phase winding and the C-phase winding), and the magnetic field force direction (i.e., the electromagnetic force direction) of the stator 1 is taken as the target direction of the rotor pre-positioning, as shown by the arrow "B + C-" in fig. 4(a), 4(B) and 4 (C). Because the rotor may be stationary at any position after the motor stops working last time, the difference between the current position of the rotor and the pre-positioning target position is described by the included angle theta between the stator magnetic field force direction and the rotor magnetic field direction:

generally, the smaller the angle θ, the less the duty ratio r and time t are required to pull the rotor to the target position, and if the angle is 180 degrees, the stator magnetic field force (i.e., electromagnetic force) can hardly pull the rotor, which makes positioning difficult. And when the duty ratio and the positioning time are calibrated, a group of maximized duty ratio and time values can be obtained through experiments only under the worst condition that the included angle is close to 180 degrees. However, for the set of parameters, for the working condition shown in fig. 4(c), that is, when the included angle is small, an excessive duty ratio may cause the rotor positioning to be overshot, and then the rotor vibrates left and right near the target position, so that a longer time is required to wait for the rotor to be stationary at the target position, and the starting time is prolonged.

It can be seen that the time Ton for starting the whole motor is the two-phase power-on time T of the S101 rotor pre-positioning stage_S101S102 total duration T of acceleration curve in acceleration stage_S102And S103, the time T required by the switching stage of the running state_S103Sum, i.e. Ton ═ T_S101+T_S102+T_S103. In the step S102, the acceleration phase and the step S103 are calibrated according to the time required for switching the operation state, so as to obtain better start stability, and then rapidity is considered. In the method of magnetically braking the rotor positioning, because the original initial position of the rotor is unknown, the stroke of moving from the original position to the preset position each time is indefinite, and the energizing time and the duty ratio must be set according to the maximum stroke. Meanwhile, the characteristics of the motor and the load are influenced by the environment (power supply voltage and temperature), and the electrifying time and the duty ratio are also set according to the worst working condition, so that three defects exist:

(1) the positioning time is too long: the power-on time is set according to the worst working condition completely, so that the starting time is too long. For example, in application of an oil pump motor of a hydraulic control system of a gearbox, the worst working conditions are 40 ℃ below zero and 10.5V power supply voltage, no-load starting is performed, positioning time of 150ms is required by experimental determination, the expected starting time of the motor of the hydraulic control system is within 250ms, and the positioning time occupies 60% of the starting time;

(2) excessive positioning current: the worst working condition needs larger duty ratio output, so that the current of the motor is larger during positioning. For example, in application of an oil pump motor of a hydraulic control system of a gearbox, the worst working conditions are 40 ℃ below zero and 16.5V power supply voltage, no-load starting is performed, the positioning current is measured by experiments to be 30A at most, the design target of a motor driving circuit is that the current is lower than 22A, the actual positioning current exceeds 36% of the design upper limit of the circuit, and the service life of a product is influenced;

(3) reduction of the start-up stability: when the original initial position of the rotor is close to the preset position, the rotor is positioned by using an overlarge duty ratio and overlong electrifying time, so that simple harmonic vibration of the rotor near the preset position is easily caused, and the motor cannot be stably started. For example, in application of an oil pump motor of a hydraulic control system of a gearbox, a 3Sigma statistical principle is adopted, that is, 99.97% of passing rate of test results must be met, meanwhile, motor starting tests are carried out on 4 system assemblies, the test times are 10000 times in total, and the starting failure rate reaches 5%.

Disclosure of Invention

The invention aims to provide a halt method, a control method and a system of a brushless direct current motor and a readable storage medium, which can position a rotor after the motor stops and solve the problems of long start time and unreliable start of the existing brushless direct current motor without a position sensor.

In order to solve the above technical problem, the present invention provides a method for stopping a brushless dc motor, the brushless dc motor including a rotor and a stator having three phases, the method comprising: and a rotor post-positioning control stage, wherein two preset phases of the three phases are conducted to draw the rotor to a target position through electromagnetic force generated by the stator.

Optionally, the method for stopping the brushless dc motor further includes: a free-stop control phase preceding the post-rotor positioning control phase in which the brushless DC motor is stopped from being driven until the rotor is stationary; and entering a post-rotor positioning control stage after the rotor is static.

Optionally, in the free-stop control stage, the brushless dc motor is stopped to be driven by a driving method of turning off the output of the three phases or conducting the output of the three phases to ground until the rotor is stationary.

Optionally, in the post-rotor positioning control stage, the preset conduction duration and the preset PWM duty cycle for conducting two phases of the three phases are set according to the current specific temperature, the current load size, and the current power supply voltage of the brushless dc motor.

Optionally, the method for stopping the brushless dc motor further includes: a rotor rear positioning parameter matrix is preset before the rotor rear positioning control stage, and the rotor rear positioning parameter matrix is related to the specific temperature, the power supply voltage, the load size, the conduction duration and the PWM duty ratio when the brushless direct current motor is stopped; and in the post-rotor positioning control stage, selecting corresponding conduction duration and PWM duty ratio from the post-rotor positioning parameter matrix according to the current specific temperature, load size and power supply voltage of the brushless direct current motor.

Optionally, the on-time in the post-positioning control phase of the rotor mainly depends on the longest time required for drawing the rotor from the angle position between the rotor magnetic field direction and the electromagnetic force direction of the stator to the target position and completely stop under the determined PWM duty control.

Optionally, the three phases of the stator are an a phase, a B phase and a C phase, respectively, and in the post-rotor positioning control stage, the mode of conducting two of the preset three phases is one of the following conducting modes: a conduction mode of phase a conduction power and phase B conduction ground, a conduction mode of phase a conduction power and phase C conduction ground, a conduction mode of phase B conduction power and phase a conduction ground, a conduction mode of phase B conduction power and phase C conduction ground, a conduction mode of phase C conduction power and phase a conduction ground, and a conduction mode of phase C conduction power and phase B conduction ground.

Optionally, the mode of conducting two of the three phases that are preset in the post-rotor positioning control stage is determined according to the mode of conducting two of the three phases in the pre-rotor positioning stage in the starting process of the brushless dc motor.

Optionally, a spatial direction corresponding to a mode for conducting two of the three phases in the rotor post-positioning control stage and a spatial direction corresponding to a mode for conducting two of the three phases in the rotor pre-positioning stage are separated by 0 degree or 60 degrees.

Based on the same inventive concept, the invention also provides a control method of the brushless direct current motor, which comprises the following steps: the method comprises a starting stage, a normal operation stage and a stopping stage, wherein in the stopping stage, the brushless direct current motor is stopped by adopting the stopping method of the brushless direct current motor; and starting the brushless direct current motor in the starting stage according to corresponding data of the stopping stage of the previous stopping of the brushless direct current motor.

Optionally, the start-up phase comprises: a rotor pre-positioning stage, in which a final rotor stop position after the previous shutdown of the brushless direct current motor is used as a rotor initial position of the starting stage, two phases of the preset three phases are conducted according to a deviation between the rotor initial position and a preset fixed rotor position, and the rotor is pulled to the fixed rotor position through electromagnetic force generated by the stator; in the acceleration stage, the power supply voltage or the phase change signal of the brushless direct current motor is changed, so that the rotating speed of the brushless direct current motor is gradually increased; and an operation state switching stage, after the brushless direct current motor reaches the required rotating speed, determining the phase change time of the brushless direct current motor by detecting the zero crossing point of the back electromotive force, so that the brushless direct current motor enters a normal operation stage.

Optionally, the three phases of the stator are phase a, phase B, and phase C, respectively, and in the rotor pre-positioning stage, the mode of conducting two preset phases of the three phases is one of the following conduction modes: the power supply comprises a conduction mode of A phase conduction power supply and B phase conduction ground, a conduction mode of A phase conduction power supply and C phase conduction ground, a conduction mode of B phase conduction power supply and A phase conduction ground, a conduction mode of B phase conduction power supply and C phase conduction ground, a conduction mode of C phase conduction power supply and A phase conduction ground, and a conduction mode of C phase conduction power supply and B phase conduction ground.

Optionally, the spatial direction corresponding to the mode for conducting two of the three phases selected by the post-rotor positioning control stage in the shutdown stage is separated by 0 degree or 60 degrees from the spatial direction corresponding to the mode for conducting two of the three phases selected by the pre-rotor positioning stage.

Optionally, the magnitude of the electromagnetic force of the stator in the rotor pre-positioning stage depends on an included angle between the direction of the electromagnetic force of the stator in the rotor post-positioning control stage of the shutdown stage and the direction of the electromagnetic force of the stator in the rotor pre-positioning stage, and the magnitude of the load of the brushless dc motor.

Optionally, in the rotor pre-positioning stage, a preset conduction duration and a preset PWM duty ratio for conducting two phases of the three phases are set according to a current specific temperature, a current supply voltage, a current load of the brushless dc motor, and an included angle between an electromagnetic force direction of the stator in the rotor post-positioning control stage of the shutdown stage of the previous shutdown and an electromagnetic force direction of the stator in the rotor pre-positioning stage.

Optionally, before the starting stage, a rotor pre-positioning parameter matrix is preset, where the rotor pre-positioning parameter matrix is related to specific temperature, power supply voltage, load size, conduction duration, PWM duty cycle when the brushless dc motor is started, and an included angle between an electromagnetic force direction of the stator in the post-rotor positioning control stage of the stopping stage of the previous stop and an electromagnetic force direction of the stator in the rotor pre-positioning stage; and in the rotor pre-positioning stage, selecting corresponding conduction duration and PWM duty ratio from the rotor pre-positioning parameter matrix according to the current specific temperature, load size, power supply voltage and the included angle of the brushless direct current motor.

Optionally, the on-time of the rotor pre-positioning stage mainly depends on the time required for rotating the rotor through the included angle to draw the rotor to the fixed rotor position and completely stop under the control of the determined PWM duty ratio.

Optionally, a rotor post-positioning parameter matrix is preset, and the rotor post-positioning parameter matrix is related to the specific temperature, the supply voltage, the load size, the conduction duration and the PWM duty ratio when the brushless dc motor is stopped; in a rotor post-positioning control stage of the shutdown stage, selecting corresponding conduction duration and PWM duty ratio from the rotor post-positioning parameter matrix according to the current specific temperature, load size and power supply voltage of the brushless direct current motor; when the brushless direct current motor is started for the first time, in the rotor pre-positioning stage, according to the current specific temperature, load size and power supply voltage of the brushless direct current motor, the corresponding conduction duration and PWM duty ratio are obtained from the rotor rear positioning parameter matrix and are used as the conduction duration and PWM duty ratio when two phases of the three phases are conducted, wherein the conduction duration and the PWM duty ratio are preset.

Optionally, the control method of the brushless dc motor further includes: and in the starting stage and the normal operation stage, monitoring whether abnormal events including motor faults or state jamming occur in real time, and directly jumping to a free stop control stage of the stop stage once the abnormal events are detected.

Based on the same inventive concept, the present invention further provides a motor controller configured to stop a brushless dc motor by using the method for stopping a brushless dc motor according to the present invention, the motor controller comprising: a shutdown command generation module configured to generate a shutdown command to stop operation of the brushless DC motor; and a rotor rear positioning control module configured to pull the rotor to a target position by an electromagnetic force generated by the stator by turning on two of the three phases set in advance after receiving the stop command.

Optionally, the motor controller further comprises a free-stop control module configured to stop driving the brushless dc motor until the rotor is stationary according to a stop command of the stop command generating module; the post rotor positioning control module is further configured to begin operation after the free-stop control module brings the rotor to a standstill.

Based on the same inventive concept, the present invention further provides a motor controller configured to start, normally operate and stop a brushless dc motor as required by using the control method of the brushless dc motor according to the present invention, the motor controller comprising: a shutdown control module, a normal control module and a startup control module,

the shutdown control module includes: a stop command generating unit configured to generate a stop command to stop an operation of the brushless dc motor; and a rotor rear positioning control unit configured to pull the rotor to a target position by an electromagnetic force generated by the stator by conducting two phases of the three phases set in advance after receiving the stop command;

the starting control module is configured to start the brushless direct current motor according to corresponding data after the stopping control module stops the brushless direct current motor last time;

the normal control module is configured to control the brushless direct current motor to work normally after the starting control module starts the brushless direct current motor.

Optionally, the motor controller further comprises a free-stop control unit configured to stop driving the brushless dc motor until the rotor is stationary according to a stop command of the stop command generation module; the post rotor positioning control module is further configured to begin operation after the free-stop control unit brings the rotor to a standstill.

Optionally, the start control module includes: a start command generating unit configured to generate a start command to start operation of the brushless DC motor; a rotor predetermined bit unit configured to take a final rotor stop position of the brushless dc motor after a previous shutdown as a rotor initial position according to the start command, and conduct two phases of the three phases, which are set in advance, according to a deviation between the rotor initial position and a preset fixed rotor position to draw the rotor to the fixed rotor position by an electromagnetic force generated from the stator; an acceleration unit configured to change a supply voltage or a commutation signal of the brushless dc motor to gradually increase a rotation speed of the brushless dc motor after the rotor pre-positioning unit pulls the rotor to the fixed rotor position; and an operation state switching unit configured to determine a phase change timing of the brushless dc motor by detecting a zero-crossing point of a back electromotive force after the brushless dc motor reaches a required rotation speed by the accelerating unit, so that the brushless dc motor enters a normal operation stage.

Optionally, the motor controller further includes an abnormal event monitoring module configured to monitor in real time whether an abnormal event including a motor fault or a state jam occurs during the process of starting the brushless dc motor by the start control module and during the process of controlling the brushless dc motor to normally operate by the normal control module, and directly trigger the shutdown control module to operate to shutdown the brushless dc motor once the abnormal event is detected.

Based on the same inventive concept, the invention also provides an electric device, which comprises a brushless direct current motor, a load and the motor controller, wherein the motor controller, the brushless direct current motor and the load are sequentially connected.

Based on the same inventive concept, the present invention further provides a readable storage medium, on which a computer program is stored, which, when executed by a processor, implements the method for stopping a brushless dc motor according to the present invention, or implements the method for controlling a brushless dc motor according to the present invention.

Compared with the prior art, the technical scheme of the invention has the following beneficial effects:

1. the stopping method of the brushless direct current motor, the motor controller and the electric device can add a rotor post-positioning control technology in the motor stopping stage, so that the motor can realize the function of positioning the rotor in advance when entering a real stopping working state, the initial position of the motor rotor is predetermined for the next motor starting, the time of the rotor pre-positioning stage of the next motor starting is shortened, the starting response time is optimized, the problem that the rotor generates simple harmonic vibration in the rotor pre-positioning stage can be avoided, the starting current is reduced, and the problems of long starting time and unreliable starting of the existing brushless direct current motor without the position sensor are solved finally. For example, in one actual measurement, the motor starting time can be shortened by 120ms, the starting current can be reduced from 30A to 15A, and the motor starting success rate can reach 100% in multiple actual measurements.

2. The control method, the motor controller and the electric device of the brushless direct current motor enable the starting of the motor to be realized according to corresponding data of the motor during the previous stopping, namely the initial position of the motor rotor during the starting can be predetermined through the previous stopping process, so that the starting time of the motor is further shortened, the problem that the rotor generates simple harmonic vibration during the starting process of the motor can be avoided, and the problems that the starting time of the existing brushless direct current motor without a position sensor is long and the starting is unreliable are finally solved.

3. Further, in the shutdown method, the control method, the motor controller and the electrical device of the brushless direct current motor, the proper two-phase conduction duration and the PWM duty ratio can be selected according to the specific problems of the motor, the power supply voltage, the load size and the like, so that the positioning currents of the post-positioning control stage and the pre-positioning stage of the rotor are optimized; and the mode of selecting and conducting two phases in the post-rotor positioning control stage is different from the mode of selecting and conducting two phases in the rotor pre-positioning stage, for example, the space directions corresponding to the conducting modes in the two stages are separated by 0 degree or 60 degrees, so that the working condition that the rotor cannot be pulled when the rotor is separated by 180 degrees is avoided, and the starting stability is enhanced.

Drawings

Fig. 1 is a schematic structural view of a brushless dc motor;

fig. 2 is a schematic diagram illustrating the steps of a conventional brushless dc motor control method;

FIG. 3 is a schematic diagram illustrating a trend of three-stage starting of a conventional brushless DC motor;

fig. 4(a) is a schematic diagram illustrating that when a conventional brushless dc motor is positioned, an included angle between a rotor magnetic field direction and a stator magnetic field force direction is greater than 180 °;

fig. 4(b) is a schematic diagram illustrating that when the conventional brushless dc motor is positioned, an included angle between the rotor magnetic field direction and the stator magnetic field force direction approaches 180 °;

fig. 4(c) is a schematic diagram illustrating that when the conventional brushless dc motor is positioned, an included angle between the rotor magnetic field direction and the stator magnetic field force direction is close to 0 °;

FIG. 5 is a schematic diagram illustrating the steps of a control method for a brushless DC motor according to an embodiment of the present invention;

FIG. 6 is a graph illustrating the trend of the rotation speed of the brushless DC motor according to the present invention;

FIG. 7 is a flow chart of a method of controlling a brushless DC motor in accordance with an embodiment of the present invention;

fig. 8(a) to 8(f) are schematic spatial direction diagrams of stator magnetic field force directions in three-phase conduction modes and respective conduction modes in the brushless dc motor according to the embodiment of the present invention;

FIG. 9 is a functional block diagram of a motor controller and electrical device according to one embodiment of the present invention;

fig. 10 is a functional block diagram of a motor controller and an electrical device according to another embodiment of the present invention.

Detailed Description

The core idea of the technical scheme of the invention is as follows: based on the rotor traction characteristic of the brushless direct current motor, compared with the existing control technology of the brushless direct current motor without a position sensor, in the process of normally stopping the motor, at least a rotor post-positioning control stage is added, for example, a free stop control stage and a rotor post-positioning control stage are added; the free stop control stage is that when the brushless DC motor receives a command of stopping working, the motor controller stops driving the brushless DC motor and waits for the rotor of the motor to be completely static from rotating; and the rotor post-positioning control stage is that two phases of the preset three phases are conducted to draw the rotor to a target position to be static through electromagnetic force generated by the stator, and the output of the motor controller is closed to enable the motor to enter a real stop working state. Therefore, the function of positioning the rotor in advance is realized, the initial position of the motor rotor is predetermined for the next motor starting, the time of the next motor starting is shortened, and the problem of harmonic vibration of the rotor during the next motor starting can be avoided, so that the problems of long starting time and unreliable starting of the conventional brushless direct current motor without a position sensor are solved.

The technical solution proposed by the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments. Advantages and features of the present invention will become apparent from the following description and from the claims. It is to be noted that the drawings are in a very simplified form and are not to precise scale, which is merely for the purpose of facilitating and distinctly claiming the embodiments of the present invention.

Referring to fig. 1, a brushless dc motor (which may be referred to as a "motor" for short) according to various embodiments of the present invention is a brushless dc motor without a position sensor, and the structure of the brushless dc motor is divided into a stator 1 and a rotor 2, where the stator 1 mainly includes an iron core 11 and

stator windings

12A, 12B, and 12C formed by coils wound around the iron core 11, the

stator windings

12A, 12B, and 12C form A, B, C three-phase windings of the motor, lead wires (not shown) of the

stator windings

12A, 12B, and 12C can be connected to a star structure and a triangle structure, and the rotor 2 mainly includes a permanent magnet 22 mounted on a central rotating shaft 21. When direct current is conducted between any two phases of stator windings of the motor, magnetic field force in a fixed direction is generated on the stator side, the rotor 2 is attracted to be aligned with the magnetic field, the purpose of pulling the rotor 2 to rotate is achieved, and the pulling force and the pulling time of the motor are mainly determined by the size of the stator magnetic force generated by PWM signal modulation and the magnetic field included angle between the stator 1 and the rotor 2.

Referring to fig. 1 and 5 to 7, an embodiment of the present invention provides a method for stopping a brushless dc motor, the brushless dc motor including a rotor 2 and a stator 1 having three phases A, B, C, the method comprising:

s501, in a free stop control stage, stopping driving the brushless direct current motor until the rotor 2 is static; and the number of the first and second groups,

and S502, in a rotor post-positioning control stage, after the rotor 2 is static, two preset phases of the three phases are conducted, so that the rotor 2 is drawn to a target position through electromagnetic force generated by the stator 1.

Specifically, after the motor normally operates (i.e., performs the closed-loop speed-regulating operation of step S500) for a period of time, whether there is a stop command (i.e., performs step S501 a) that the motor needs to stop operating is monitored in real time (e.g., the stop command may be that the motor controller is on electricity)A normal stop command generated when the motor needs to be stopped due to the fact that the motor normally finishes a task, or a forced stop command generated when a motor controller needs to forcibly stop the motor due to an abnormal event), once the stop command exists, the free stop control stage S501 can be entered, whether rapid stop is needed or not can be further judged (namely, the step S501b is executed), if yes, the step S501d is executed, three phases A, B, C of the motor are all conducted to the ground, and the rotor 2 of the motor can be rapidly decelerated to be completely stationary in a short time; if not, step S501c is executed to turn off the output of the three-phase A, B, C of the motor. Then, it is determined whether the rotor 2 is completely stationary (i.e., step S501e is executed), and when the rotor 2 is completely stationary, the control stage S502 of post-rotor positioning is entered. That is, in the free stop control stage S501, the brushless dc motor may be stopped from being driven until the rotor 2 completely stops by adopting a driving method of turning off the A, B, C three-phase output of the brushless dc motor or a driving method of turning on the A, B, C three-phase output of the brushless dc motor with the ground. In S501, in the free stop control stage, the time (also referred to as stop waiting time) t from the rotation to the rest of the motor_stopMainly depends on the rotation speed n when the motor starts to stop and the current load size m of the motor. The time t consumed by the free-run control phase_stopIs a function of the speed n and the load m, i.e. t_stopG (n, m). In general, the larger n or the smaller m, the larger t_stopThe longer. For example, for items such as oil pump motor control, t_stopIs determined according to an oil pump bench (load determination) test, and the rotating speed n is the highest rotating speed allowed to work.

In the post-positioning control stage of the rotor of S502, the current specific temperature T of the brushless dc motor may be determined_motorA load size m and a supply voltage V, setting a conduction duration t for conducting two of the preset A, B, C three phases_postAnd PWM (pulse Width modulation) duty ratio r_postThe size of (2).

Wherein, in the post-positioning control stage of S502 rotor, the output PWM duty ratio r_postDirectly determining the three-phase winding of the

stator

212A, 12B, 12C, and the required electromagnetic force depends mainly on the angle θ between the direction of the magnetic field force of the stator and the direction of the magnetic field of the rotor and the load size m. The current specific temperature T of the motor is directly influenced by the supply voltage V of the motor to the electromagnetic force of the stator 1 of the motor_motorAnd directly influences the magnetic field characteristics of the rotor 2, so that the PWM duty ratio r_postIs a function of the following parameters, namely:

r_post＝f(θ，V，T_motor，m)

in general, the larger θ or smaller V or smaller m or T_motorThe larger the value r_postThe larger.

In the post-positioning control stage of the rotor of S502, the preset conduction duration t of the two phases is conducted_postMainly depending on the determined PWM duty cycle r_postUnder the output, the rotor 2 is pulled to a target position from any included angle theta position of 0-180 Degrees (DEG) and completely stands still for the longest time. For example, for items such as oil pump motor control, the PWM duty ratio r_postAnd on duration t_postThe method is determined according to an oil pump bench (starting load determination) test, and the calibration working condition is defined as that theta is 180 degrees, an allowable power supply voltage range and an allowable motor working temperature r range.

As an example, in order to more rapidly determine the PWM duty r in the post-rotor positioning control stage of S502_postAnd on duration t_postBefore the free-stop control stage S501, a post-rotor positioning parameter matrix I may be preset_postSaid rotor post-positioning parameter matrix I_postAnd the specific temperature (namely the current temperature) T when the brushless DC motor is stopped_motorSupply voltage V, load size m and conduction duration t_postAnd PWM duty ratio r_postAre all related, i.e. I_post＝[T_motor V m t_post r_post]Thereby, in the post-rotor positioning control stage S502, the specific temperature T of the brushless DC motor is determined according to the current temperature_motorLoad size m and supply voltage V, from the rotor back-positioning parameter matrix I_postTo select the corresponding on-time duration t_postAnd PWM duty ratio r_postAnd according to PWM duty ratio r_postConducting the predetermined two phases (i.e. performing step S502a), and then conducting for the duration t_postKeeping conducting two phases preset until the duration time t_postWhen this is completed (i.e., step S502b is executed), the three-phase output A, B, C of the motor is completely turned off, and the entire motor stop control process is completed (i.e., step S503 is executed).

Referring to fig. 8(a) to 8(f), in the rotor post-positioning control stage of S502, a mode of conducting two of the three phases that are set in advance (i.e., a conducting mode in the rotor post-positioning control stage) is one of the following conducting modes: a conducting pattern of B-phase conducting power and C-phase conducting ground (as shown in fig. 8(a), a corresponding stator magnetic field force direction, i.e. a spatial direction, is 0 degrees), a conducting pattern of B-phase conducting power and a-phase conducting ground (as shown in fig. 8(B), a corresponding stator magnetic field force direction, i.e. a spatial direction, is 60 degrees), a conducting pattern of C-phase conducting power and a-phase conducting ground (as shown in fig. 8(C), a corresponding stator magnetic field force direction, i.e. a spatial direction, is 120 degrees), a conducting pattern of C-phase conducting power and B-phase conducting ground (as shown in fig. 8(d), a corresponding stator magnetic field force direction, i.e. a spatial direction, is 180 degrees), a conducting pattern of a-phase conducting power and B-phase conducting ground (as shown in fig. 8(e), a corresponding stator magnetic field force direction, i.e. a spatial direction, is 240 degrees), a conducting pattern of a-phase conducting power and C-phase conducting ground (as shown in fig. 8(f), the corresponding stator magnetic field force direction, i.e., the spatial direction, is 300 degrees). Optionally, in the S502 post-rotor positioning control stage, a mode (referred to as a conduction mode of the rotor post-positioning control stage for short) for conducting two phases of the three phases that are preset in the rotor post-positioning control stage is determined according to a mode (referred to as a conduction mode of the rotor pre-positioning stage for short) for conducting two phases of the three phases in the S504 rotor pre-positioning stage in the starting process of the brushless dc motor, for example, a spatial direction corresponding to the conduction mode selected in the rotor post-positioning control stage is separated by 0 degree or 60 degrees from a spatial direction corresponding to the conduction mode selected in the rotor pre-positioning stage, so that another two phases different from the rotor positioning in the S504 rotor pre-positioning stage are selected in the S502 post-rotor positioning control stage for conducting, thereby avoiding a working condition that the rotor 2 cannot be pulled when an included angle between the spatial directions of two times of positioning is 180 degrees, thereby achieving the purpose of enhancing the starting stability. Specifically, when the conduction mode of the rotor pre-positioning stage in S504 is the conduction mode of the phase a conduction power supply and the phase B conduction ground as shown in fig. 8(e), one of the conduction modes shown in fig. 8(d) to 8(f) may be selected as the conduction mode of the rotor post-positioning control stage in S501, that is, the conduction mode of the rotor post-positioning control stage in S501 may be the conduction mode of the phase C conduction power supply and the phase B conduction ground as shown in fig. 8(d), the conduction mode of the phase a conduction power supply and the phase B conduction ground as shown in fig. 8(e), or the conduction mode of the phase a conduction power supply and the phase C conduction ground as shown in fig. 8 (f).

The stopping method of the brushless direct current motor of the embodiment can enable the motor stopping stage to comprise a free stopping control stage and a rotor post-positioning control stage, so that the motor enters a real stopping working state after the two stages are completed, and the function of rotor pre-positioning is realized, so that the initial position of the motor rotor is predetermined for the next motor starting, the time of the rotor pre-positioning stage of the next motor starting is further shortened, the starting response time is optimized, the problem that the rotor generates harmonic vibration in the rotor pre-positioning stage can be avoided, the starting current is reduced, and the problems that the starting time of the existing brushless direct current motor without the position sensor is long and the starting is unreliable are finally solved.

Based on the same inventive concept, an embodiment of the present invention further provides a method for controlling a brushless dc motor, including: a starting stage, a normal operation stage and a stopping stage, wherein in the stopping stage, the stopping method of the brushless direct current motor in the above embodiment of the invention is adopted to stop the brushless direct current motor; and starting the brushless direct current motor in the starting stage according to corresponding data of the stopping stage of the previous stopping of the brushless direct current motor.

The method for controlling the brushless dc motor of the present embodiment is described in detail below based on the existing "three-stage" starting method and the stopping method in the above embodiment.

With reference to fig. 1 and fig. 5 to fig. 7, the method for controlling the brushless dc motor of the present embodiment includes the following steps:

and S500, in a normal operation stage, namely that the current motor is in a closed-loop speed regulation stage, the motor normally works in the stage so as to drive the load to perform corresponding operation (such as moving or rotating).

S501a, monitoring in real time whether there is a shutdown command that the motor needs to stop working, where the shutdown command may be a normal shutdown command generated when the motor controller needs to stop the motor after the motor normally completes a task, or may be a forced shutdown command generated when the motor controller needs to forcibly stop the motor due to an abnormal event, and once there is a shutdown command, the method may enter the free shutdown control stage S501.

S501, the free stop control stage, first, may execute step S501 b: judging whether quick shutdown is needed, if so, executing step S501 d: all three phases A, B, C of the motor are conducted to the ground so that the rotor 2 of the motor can be decelerated quickly to be completely stationary in a short time; if not, go to step S501 c: turn off the output of the three phases A, B, C of the motor; after that, step S501e is executed: and judging whether the rotor 2 is completely static or not, and entering a rotor rear positioning control stage S502 after the rotor 2 is completely static.

S502, the rotor post-positioning control stage, first, executes step S502 a: according to the current specific temperature T of the brushless DC motor_motorA load size m and a supply voltage V, setting a conduction duration t for conducting two of the preset A, B, C three phases_postAnd PWM (pulse Width modulation) duty ratio r_postOr, from the preset rotor, positioning the parameter matrix I_postIn the respective on-time t_postAnd PWM duty ratio r_postAnd according to PWM duty ratio r_postConducting the preset two phases; then, step S502b is executed: judging the duration t of conduction_postIf not, continuing to keep the guideTwo phases are preset, and if yes, the process goes to step S503.

And S503, completely closing A, B, C three-phase output of the motor, completing the whole motor stop control process, and waiting for the next start.

S504, in the rotor pre-positioning stage, first, step S504a is executed: judging whether a motor starting operation command (namely a motor starting command) is received, if not, continuing to loop the steps S503 and S504a, if yes, executing the step S504 b: judging whether the system is started for the first time after being electrified, if so, executing a step S504d, and according to the current power supply voltage V of the motor, the load size m and the motor temperature T_motorPost-positioning parameter matrix I from rotor_postTo select the corresponding on-time duration t_postAnd PWM duty ratio r_postAccording to t_postAnd r_postConducting two phases preset in the rotor pre-positioning stage to rotate the rotor 2 to a preset fixed rotor position, and then entering an acceleration stage S505, if not, executing a step S504c, and according to the current power supply voltage V, the load size m and the motor temperature T of the motor_motorSetting the preset conduction duration t of two phases in the pre-positioning stage of the rotor_preAnd PWM (pulse Width modulation) duty ratio r_preOr, pre-positioning the parameter matrix I from a pre-set rotor_preTo select the corresponding on-time duration t_preAnd PWM duty ratio r_preAccording to t_preAnd r_preThe two preset phases are conducted to rotate the rotor 2 to the preset fixed rotor position, and then the acceleration stage S505 is performed. That is, to quickly determine t_preAnd r_preBefore the rotor pre-positioning stage S504, a rotor pre-positioning parameter matrix I may be preset_preSaid rotor pre-positioning parameter matrix I_preAnd the specific temperature T when the brushless DC motor is started_motorThe power supply voltage V, the load magnitude m, the conduction duration, the PWM duty cycle, and the angle α between the electromagnetic force direction of the stator (i.e., the magnetic field force direction) in the post-positioning control stage of the rotor in the shutdown stage and the electromagnetic force direction of the stator (i.e., the magnetic field force direction) in the pre-positioning stage of the rotor are all related.Wherein, the duty ratio r output in the rotor pre-positioning stage S504_preThe magnitude of the electromagnetic force generated by the three-phase winding of the stator is directly determined, and the required electromagnetic force mainly depends on the angle α between the direction of the magnetic field force of the stator (i.e., the direction of the electromagnetic force) in the post-positioning control stage S502 of the rotor and the direction of the magnetic field force of the stator (i.e., the direction of the electromagnetic force) in the pre-positioning stage S504 of the rotor and the magnitude m of the load. Since the supply voltage V of the motor directly influences the electromagnetic force of the stator 1 of the motor, the motor temperature T_motorAnd directly influences the magnetic field characteristics of the rotor 2, so that the duty ratio r_preIs the included angle alpha and the motor temperature T_motorA function of the supply voltage V and the load size m, i.e. r_pre＝f(α，V,T_motorM), after the conducting phases (i.e. two conducting phases of three phases, i.e. conducting mode) of the rotor pre-positioning stage S504 and the rotor post-positioning control stage S502 are determined, the included angle α is solidified, and V is smaller or m is smaller or T is smaller_motorThe larger the value r_preThe larger. Duration of conduction t_preMainly depending on the duty cycle r being determined_preAnd outputting the time for pulling the rotor 2 to a preset fixed rotor position through an angle alpha and completely standing. For items such as oil pump motor control, the duty ratio r_preAnd on duration t_preThe calibration condition is defined as alpha being 0 degree or 60 degrees, an allowable power supply voltage range and an allowable motor working temperature range. Referring to fig. 8(a) to 8(f), in S504, in the rotor pre-positioning stage, the mode of conducting two of the three phases that are set in advance (i.e., the conducting mode in the rotor pre-positioning stage) is one of the following conducting modes: a conduction pattern of B-phase conduction power and C-phase conduction ground (as shown in fig. 8(a), the corresponding stator magnetic field force direction, i.e., the spatial direction, is 0 degree), a conduction pattern of B-phase conduction power and a-phase conduction ground (as shown in fig. 8(B), the corresponding stator magnetic field force direction, i.e., the spatial direction, is 60 degrees), a conduction pattern of C-phase conduction power and a-phase conduction ground (as shown in fig. 8(C), the corresponding stator magnetic field force direction, i.e., the spatial direction, is 120 degrees), and a conduction pattern of C-phase conduction power and B-phase conduction ground (as shown in fig. 8(d), a conduction pattern of C-phase conduction power and B-phase conduction ground (as shown in fig. 8(d)The corresponding direction of the magnetic force of the stator, i.e. the spatial direction, is 180 degrees), the conduction mode of the phase a conducting power supply and the phase B conducting ground (as shown in fig. 8(e), the corresponding direction of the magnetic force of the stator, i.e. the spatial direction, is 240 degrees), and the conduction mode of the phase a conducting power supply and the phase C conducting ground (as shown in fig. 8(f), the corresponding direction of the magnetic force of the stator, i.e. the spatial direction, is 300 degrees). Optionally, in the S502 rotor post-positioning control stage, the conduction mode in the rotor post-positioning control stage is determined according to the conduction mode in the S504 rotor pre-positioning stage, for example, the spatial direction corresponding to the conduction mode selected in the rotor post-positioning control stage is separated from the spatial direction corresponding to the conduction mode selected in the rotor pre-positioning stage by 0 degree or 60 degrees, so that the other two phases different from the rotor positioning in the S504 rotor pre-positioning stage are selected to be conducted in the S502 rotor post-positioning control stage, thereby avoiding the working condition that the rotor 2 cannot be pulled when the included angle of the spatial directions including the two positioning steps is 180 degrees, and further achieving the purpose of enhancing the starting stability.

And S505, an acceleration stage, namely an open loop acceleration stage, wherein the external voltage or the phase change signal of the motor is artificially changed in the acceleration stage, so that the rotating speed of the motor is gradually increased from a standstill state. After the rotor 2 is pre-positioned successfully, the applied voltage and the phase-change signal of the motor must be artificially changed to drive the motor to do accelerated motion, so that the accelerated speed is accelerated to a speed required by the zero-crossing point, wherein the strength of the back electromotive force can be used for detecting the zero-crossing point. In general, in practical applications, an acceleration curve needs to be set according to specific motor characteristics and loads to control the switching frequency and the PWM duty ratio of the commutation signal.

S506, the operation state switching stage, that is, after the motor reaches the required rotation speed in the acceleration stage, the motor is switched from the acceleration stage S505 to the normal operation stage S500 of the motor, and the operation state switching stage S506 is to determine the phase change time by detecting the zero crossing point of the back electromotive force, so that the motor enters the normal operation stage S500. When the motor reaches a certain rotating speed through an acceleration stage, the back electromotive force signal can be accurately detected, and a driving mode of motor phase change is triggered by judging a characteristic signal point (called a zero crossing point) of the motor to replace an artificially set phase change frequency.

Thus, the steps S500 to S506 are repeatedly circulated, so that the motor can be started, operated, and stopped as needed.

Optionally, in the starting stages S504 to S506 and the normal operation stage S500, step S507 may be further performed: and monitoring whether abnormal events including motor faults or state jamming occur in real time, and directly jumping to a free stop control stage S501 of the stop stage once the abnormal events are detected.

As can be seen from the above detailed description of the control method of the brushless dc motor of the present embodiment, the control method of the brushless dc motor of the present embodiment is mainly distinguished from the prior art shown in fig. 2 to 4 by the following points:

1) the working conditions of rotor positioning are different: in the prior art, rotor pre-positioning is only performed when a motor is started, and the working condition of the embodiment is that when the motor stops working and stops working immediately after the motor stops working and stops working, the position of the rotor 2 is positioned in advance (namely, a rotor post-positioning stage) no matter whether the motor receives a new starting command or not, and the aim is to shorten the time required by rotor pre-positioning during starting;

2) the working modes of rotor positioning are different: in the prior art, when the rotor is pre-positioned, the required maximum duty ratio r is set according to the worst working condition_preOutput and longest on duration t_pre(ii) a In the rotor pre-positioning stage S504 of the present embodiment, the desired duty cycle output r_preAnd on duration t_preCalibrating according to the deviation between the position of the fixed rotor and the position of the rotor during the previous shutdown, and establishing a rotor prepositioning parameter matrix I according to different motor temperatures and power supply voltages_preThe goal is to optimize the rotor pre-positioning current;

3) the conduction modes of the stator are different: in the prior art, when a rotor is pre-positioned, a certain two-phase conduction mode of a calibrated motor is selected, and the condition that the direction of the generated stator magnetic field force and the direction of the rotor magnetic field are 180 degrees mutually may occur, which may cause the working condition that the rotor cannot be pulled to exist, so that the motor is not started stably; in the embodiment, a primary rotor rear positioning function is added in the shutdown stage, and the selection of the other two phases different from the rotor pre-positioning stage is conducted, that is, the conduction mode of the rotor rear positioning stage is different from the conduction mode of the rotor pre-positioning stage, so that the condition that the rotor cannot be pulled when the included angle between the magnetic field force direction of the stator and the magnetic field direction of the rotor is 180 degrees is avoided, and the starting stability of the motor is enhanced.

Through actual measurement, the control method of the brushless direct current motor of the embodiment can shorten the rotor prepositioning time from 150ms to 30ms when the motor is started, reduce the rotor prepositioning current from 30A to 15A, and enable the starting success rate to be close to 100%.

Based on the same inventive concept, referring to fig. 9, an embodiment of the present invention further provides a motor controller 30 configured to stop the brushless dc motor by using the above-mentioned stop method for the brushless dc motor according to the embodiment of the present invention, where the motor controller 30 includes: a startup control module 301, a normal control module 302, a shutdown command generation module 303, a free-stop control module 304, a rotor post-positioning control module 305, and an abnormal event monitoring module 306. The starting control module 301 is used for starting the motor according to a starting command of the motor, the normal control module 302 is used for controlling the motor to normally work, the stop command generating module 303 is used for generating a stop command for stopping the work of the brushless direct current motor, the free stop control module 304 is used for stopping driving the brushless direct current motor until the rotor is static according to the stop command generated by the stop command generating module 303, the rotor rear positioning control module 305 is used for pulling the rotor to a target position through electromagnetic force generated by the stator by conducting two phases of the three preset phases after the free stop control module 304 makes the rotor static, the abnormal event monitoring module 306 is used for monitoring whether an abnormal event including motor failure or state locking occurs in real time in the process that the starting control module 301 controls the motor to start and in the process that the normal control module 302 controls the motor to normally work, upon detecting the occurrence of the abnormal event, the direct trigger shutdown command generation module 303 generates a corresponding shutdown command to cause the shutdown control module to shutdown the brushless dc motor.

Please refer to fig. 7, the shutdown command generating module 303 of this embodiment is substantially configured to implement steps S501a to S501b, the free-shutdown control module 304 is substantially configured to implement steps S501c to S501e, the post-rotor positioning control module 305 is substantially configured to implement steps S502a to S502b and S503, and for how the free-shutdown control module 304 and the post-rotor positioning control module 305 implement the corresponding steps, reference may be made to all descriptions of the free-shutdown control phase and the post-rotor positioning control phase above, and details are not repeated herein.

It is understood that the startup control module 301, the normal control module 302, the shutdown command generation module 303, the free-stop control module 304, the post-rotor positioning control module 305, and the abnormal event monitoring module 306 may be combined in one module, or any one of them may be split into multiple modules, or at least part of the functions of one or more of these modules may be combined with at least part of the functions of the other modules and implemented in one module. According to an embodiment of the present invention, at least one of the startup control module 301, the normal control module 302, the shutdown command generation module 303, the free-stop control module 304, the post-rotor positioning control module 305, and the abnormal event monitoring module 306 may be implemented at least in part as a hardware circuit, such as a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), a system on a chip, a system on a substrate, a system on a package, an Application Specific Integrated Circuit (ASIC), or may be implemented in hardware or firmware in any other reasonable manner of integrating or packaging a circuit, or in a suitable combination of three implementations of software, hardware, and firmware. Alternatively, at least one of the startup control module 301, the normal control module 302, the shutdown command generation module 303, the free-stop control module 304, the rotor post-positioning control module 305, and the abnormal event monitoring module 306 may be at least partially implemented as a computer program module that, when executed by a computer, may perform the functions of the respective module.

The present embodiment further provides an electrical apparatus, which includes a brushless dc motor 40, a load 60, and the motor controller 30, where the motor controller 30, the brushless dc motor 40, and the load 60 are connected in sequence. The electric device may be a household appliance (e.g., an air conditioner, a hair dryer, a bladeless fan washing machine, an air purifier, a range hood, an electric fan, a refrigerator, a dust collector, etc.), an office device (e.g., a scanner, a copier, a printer, a paper shredder, etc.), an industrial automation device (e.g., an industrial sewing machine, a textile machine, a brushless electric tool, an electric vehicle, a machine tool, a robot, an elevator, an automatic door control system, etc.), an aerospace device (e.g., a high-speed centrifuge, a gyro motor, a simulation turntable, an inertial navigation testing device), wherein the electric vehicle is, for example, an electric tricycle, a four-wheel vehicle, a station wagon, a park vehicle, an electric forklift, an electric truck, an electric bus, etc.

Based on the same inventive concept, referring to fig. 10, another embodiment of the present invention further provides a motor controller 31 configured to start, operate and stop the brushless dc motor 40 as required by using the control method of the brushless dc motor shown in fig. 7. The motor controller 31 includes: a shutdown control module 313, a normal control module 312, a startup control module 311, and an abnormal event monitoring module 314.

The shutdown control module 313 includes: a stop command generating unit 313a, a free stop control unit 313b, and a post-rotor positioning control unit 313c, wherein the stop command generating unit 313a is configured to generate a stop command to stop the operation of the brushless dc motor 40; the free-stop control unit 313b is configured to stop driving the brushless dc motor 40 until the rotor is stationary according to the corresponding stop command generated by the stop command generating unit 313 a; the rotor rear positioning control unit 313c is configured to pull the rotor of the motor 40 to a target position by electromagnetic force generated by the stator of the motor 40 by conducting two phases of the three phases set in advance after the free stop control unit 313b makes the rotor of the motor 40 stationary. The start control module 311 includes a start command generating unit 311a, a rotor pre-positioning unit 311b, an accelerating unit 311c, and an operating state switching unit 311d, wherein the start command generating unit 311a is configured to generate a start command for starting the operation of the brushless dc motor 40; the rotor predetermined bit unit 311b is configured to take a final rotor stop position of the brushless dc motor 40 after the previous shutdown as a rotor initial position according to the start command generated by the start command generating unit 311a, and conduct two phases of the preset three phases of the stator of the motor 40 according to a deviation between the rotor initial position and a preset fixed rotor position to draw the rotor of the motor 40 to the fixed rotor position by an electromagnetic force generated by the stator of the motor 40; the accelerating unit 311c is configured to change the supply voltage or the commutation signal of the brushless dc motor 40 after the rotor pre-positioning unit 311b pulls the rotor to the fixed rotor position, so that the brushless dc motor 40 gradually increases the rotation speed; the operation state switching unit 311d is configured to determine the phase change time of the brushless dc motor 40 by detecting the zero crossing point of the back electromotive force after the accelerating unit 311c makes the brushless dc motor 40 reach the required rotation speed, so as to make the brushless dc motor 40 enter the normal operation stage. The normal control module 312 is configured to control the brushless dc motor 40 to normally operate after the start control module 311 starts the brushless dc motor 40. The abnormal event monitoring module 314 is configured to monitor whether an abnormal event including a motor fault or a state jam occurs in real time during the process of starting the brushless dc motor 40 by the start control module 311 and during the process of controlling the brushless dc motor 40 to normally operate by the normal control module 312, and directly trigger the shutdown control module 313 to operate to shutdown the brushless dc motor 40 once the abnormal event is detected.

Please refer to fig. 7, the shutdown command generating unit 313a of this embodiment is substantially configured to implement steps S501a to S501b, the free shutdown control unit 313b is substantially configured to implement steps S501c to S501e, and the rotor post-positioning control unit 313c is substantially configured to implement steps S502a to S502b and S503, and for how the free shutdown control unit 313b and the rotor post-positioning control unit 313c implement the corresponding steps, reference may be made to all the descriptions of the free shutdown control phase and the rotor post-positioning control phase above, and details are not repeated here. The start command generating unit 311a is substantially for implementing steps S504a to S504b, the rotor pre-positioning unit 311b is substantially for implementing steps S504c to S504d, the accelerating unit 311c is substantially for implementing step S505, and the operating state switching unit 311d is substantially for implementing step S506, and for how to implement the corresponding steps of the start command generating unit 311a, the rotor pre-positioning unit 311b, the accelerating unit 311c, and the operating state switching unit 311d, reference may be made to all the descriptions about the three-stage start scheme (the rotor pre-positioning stage, the accelerating stage, and the operating state switching stage) in the foregoing, and details thereof are not repeated herein

It is understood that the start command generating unit 311a, the rotor pre-positioning unit 311b, the acceleration unit 311c in the start control module 311, the operation state switching unit 311d, and the stop command generating unit 313a, the free stop control unit 313b, and the rotor post-positioning control unit 313c in the stop control module 313 may be respectively combined into one module to be implemented, or any one of them may be split into a plurality of sub-units, or at least part of the functions of one or more of these units may be combined with at least part of the functions of the other units and implemented in one module. Further, the start control module 311, the normal control module 312, the stop control module 313, and the abnormal event monitoring module 314 may be combined into one module, or any one of the modules may be divided into a plurality of units, or at least part of the functions of one or more of the modules may be combined with at least part of the functions of the other modules and implemented in one module. According to an embodiment of the present invention, at least one of the start-up control module 311, the normal control module 312, the stop control module 313 and the abnormal event monitoring module 314 may be at least partially implemented as a hardware circuit, such as a Field Programmable Gate Array (FPGA), a Programmable Logic Array (PLA), a system on a chip, a system on a substrate, a system on a package, an Application Specific Integrated Circuit (ASIC), or may be implemented in hardware or firmware in any other reasonable manner of integrating or packaging a circuit, or in a suitable combination of three implementations of software, hardware and firmware. Alternatively, at least one of the start control module 311, the normal control module 312, the stop control module 313, and the abnormal event monitoring module 314 may be at least partially implemented as a computer program module that, when executed by a computer, may perform the functions of the respective modules.

Referring to fig. 10, the present embodiment further provides an electrical apparatus, which includes a brushless dc motor 40, a load 60, and the motor controller 31 shown in fig. 10, wherein the motor controller 31, the brushless dc motor 40, and the load 60 are connected in sequence. The electrical device may be a household appliance (e.g., an air conditioner, a hair dryer, a bladeless fan washing machine, an air purifier, a range hood, an electric fan, a refrigerator, a dust collector, etc.), an office device (e.g., a scanner, a copier, a printer, a shredder, etc.), an industrial automation device (e.g., an industrial sewing machine, a textile machine, a brushless electric tool, an electric vehicle, a machine tool, a robot, an elevator, an automatic door control system, etc.), an aerospace device (e.g., a high-speed centrifuge, a gyro motor, a simulation turntable, an inertial navigation testing device), wherein the electric vehicle is, for example, an electric tricycle, a four-wheeled vehicle, a station wagon, a park vehicle, an electric forklift, an electric truck, an electric motor coach, etc.

Based on the same inventive concept, an embodiment of the present invention further provides a computer-readable storage medium, on which a computer program is stored, the computer program may include codes/computer-executable instructions, and when the computer program is executed by a processor, the method for stopping the brushless dc motor and any variation thereof according to the embodiments of the present invention are implemented, or the method for controlling the brushless dc motor and any variation thereof according to the embodiments of the present invention are implemented. The computer readable storage medium may be any medium that can contain, store, communicate, propagate, or transport the instructions. For example, the computer readable storage medium may include, but is not limited to, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, apparatus, device, or propagation medium. Specific examples of the computer storage medium include: magnetic storage devices such as magnetic tape or Hard Disk Drives (HDDs); optical storage devices, such as compact disks (CD-ROMs); a memory, such as a Random Access Memory (RAM) or a flash memory; and/or wired/wireless communication links.

In conclusion, the control scheme of the brushless direct current motor and the electric device applying the control scheme of the invention realize the function of positioning the rotor position in advance under the stop working condition of the motor based on the existing three-stage type position-sensorless brushless direct current motor starting control method, thereby optimizing the starting response time, reducing the starting current and enhancing the starting stability.

The invention relates to a control scheme of a brushless direct current motor and an electric device applying the control scheme, which are designed on the basis of taking a position sensorless brushless direct current motor driven by square waves as a target object and a three-section starting technology, and are still applicable to other motor control systems adopting a rotor pre-positioning technology during starting; in order to be more beneficial to the application of the rotor rear positioning technology, the invention adds free stop control, and the technical scheme of directly controlling the rotor rear positioning without adopting the free stop control still should be taken as a flexible design of the technical scheme provided by the invention.

It will be apparent to those skilled in the art that various changes and modifications may be made in the invention without departing from the spirit and scope of the invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include such modifications and variations.

Claims

1. A method of stopping a brushless dc motor including a rotor and a stator having three phases, comprising: a free stop control stage and a rotor post-positioning control stage; stopping driving the brushless direct current motor until the rotor is static in the free stop control stage, and entering a rotor post-positioning control stage after the rotor is static; in the post-positioning control stage of the rotor, the rotor is drawn to a target by electromagnetic force generated by the stator by conducting two phases of the three phases which are presetA position, wherein, according to the current specific temperature, load size and supply voltage of the brushless DC motor, the preset conduction duration and PWM duty ratio of two phases in the three phases are set, and the PWM duty ratio r_postIn particular a functional relation r_post =f (θ，V，T_motorM), wherein the smaller θ is, r_postThe smaller theta is the included angle between the current magnetic field force direction of the stator and the magnetic field direction of the rotor of the brushless direct current motor, V is the current power supply voltage of the brushless direct current motor, and T is_motorSetting the current specific temperature of the brushless direct current motor as m, wherein m is the current load of the brushless direct current motor; and the spatial direction corresponding to the mode for conducting two phases of the three phases in the rotor post-positioning control stage is separated from the spatial direction corresponding to the mode for conducting two phases of the three phases in the rotor pre-positioning stage in the starting process of the brushless direct current motor by 0 degree or 60 degrees.

2. The method for stopping a brushless dc motor according to claim 1, wherein in the free stop control stage, the driving of the brushless dc motor is stopped by turning off the outputs of the three phases or turning the outputs of the three phases on to ground until the rotor is stationary.

3. The method of stopping a brushless dc motor according to claim 1, wherein the on-time in the post-rotor positioning control phase depends mainly on a maximum time required to pull the rotor from an angle position between a rotor magnetic field direction and an electromagnetic force direction of the stator to the target position and completely stop under the determined PWM duty control.

4. The method of stopping a brushless dc motor according to claim 1, wherein the three phases of the stator are a phase, B phase, and C phase, respectively, and the mode of conducting two phases of the three phases, which are set in advance, in the post-rotor positioning control stage is one of the following conduction modes: the power supply comprises a conduction mode of A phase conduction power supply and B phase conduction ground, a conduction mode of A phase conduction power supply and C phase conduction ground, a conduction mode of B phase conduction power supply and A phase conduction ground, a conduction mode of B phase conduction power supply and C phase conduction ground, a conduction mode of C phase conduction power supply and A phase conduction ground, and a conduction mode of C phase conduction power supply and B phase conduction ground.

5. A method of controlling a brushless dc motor, comprising: a start-up phase, a normal operation phase and a stop phase, wherein in the stop phase, the brushless DC motor is stopped by adopting the stop method of the brushless DC motor according to any one of claims 1-4; and starting the brushless direct current motor in the starting stage according to corresponding data of the stopping stage of the previous stopping of the brushless direct current motor.

6. The method of controlling a brushless dc motor according to claim 5, wherein the start-up phase comprises:

a rotor pre-positioning stage, in which a final rotor stop position after the previous shutdown of the brushless direct current motor is used as a rotor initial position of the starting stage, two phases of the preset three phases are conducted according to a deviation between the rotor initial position and a preset fixed rotor position, and the rotor is pulled to the fixed rotor position through electromagnetic force generated by the stator;

in the acceleration stage, the power supply voltage or the phase change signal of the brushless direct current motor is changed, so that the rotating speed of the brushless direct current motor is gradually increased; and the number of the first and second groups,

and an operation state switching stage, namely determining the phase change time of the brushless direct current motor by detecting the zero crossing point of back electromotive force after the brushless direct current motor reaches the required rotating speed, so that the brushless direct current motor enters a normal operation stage.

7. The method of controlling a brushless dc motor according to claim 6, wherein the three phases of the stator are a phase, B phase, and C phase, respectively, and the mode of conducting two phases of the three phases, which are set in advance, in the rotor pre-positioning stage is one of the following conduction modes: a conduction mode of phase a conduction power and phase B conduction ground, a conduction mode of phase a conduction power and phase C conduction ground, a conduction mode of phase B conduction power and phase a conduction ground, a conduction mode of phase B conduction power and phase C conduction ground, a conduction mode of phase C conduction power and phase a conduction ground, and a conduction mode of phase C conduction power and phase B conduction ground.

8. The method according to claim 6, wherein in the rotor pre-positioning stage, the conduction duration and the PWM duty ratio for conducting two of the three phases are set according to the current specific temperature, the current supply voltage, the load magnitude of the brushless DC motor and the included angle between the electromagnetic force direction of the stator in the post-positioning control stage of the shutdown stage of the previous shutdown and the electromagnetic force direction of the stator in the rotor pre-positioning stage.

9. The method according to claim 6, wherein a rotor pre-positioning parameter matrix is preset before the start-up phase, and the rotor pre-positioning parameter matrix is related to specific temperature, power supply voltage, load size, conduction duration, PWM duty ratio when the brushless DC motor is started, and included angles between the electromagnetic force direction of the stator in the post-positioning control phase of the rotor in the stop phase of the previous stop and the electromagnetic force direction of the stator in the pre-positioning phase of the rotor; and in the rotor pre-positioning stage, selecting corresponding conduction duration and PWM duty ratio from the rotor pre-positioning parameter matrix according to the current specific temperature, load size, power supply voltage and the included angle of the brushless direct current motor.

10. A method of controlling a brushless dc motor according to claim 8 or 9, wherein the duration of the on-state of the rotor pre-positioning phase is determined by the time required to rotate the rotor through the angle to a fixed rotor position and come to a complete standstill under a determined PWM duty cycle control.

11. The control method of a brushless dc motor according to claim 5, further comprising: and in the starting stage and the normal operation stage, monitoring whether abnormal events including motor faults or state jamming occur in real time, and directly jumping to a free stop control stage of the stop stage once the abnormal events are detected.

12. A motor controller configured to stop a brushless dc motor by the method for stopping a brushless dc motor according to any one of claims 1 to 4, the motor controller comprising:

a shutdown command generation module configured to generate a shutdown command to stop operation of the brushless DC motor;

a free stop control module configured to stop driving the brushless DC motor until the rotor is stationary according to a stop command of the stop command generation module; and the number of the first and second groups,

a rotor rear positioning control module configured to start operating after the free-stop control module makes the rotor stationary, and to pull the rotor to a target position by electromagnetic force generated by the stator by conducting two phases of the three phases, wherein a conducting duration and a PWM duty ratio are set according to a current specific temperature, a load size and a power supply voltage of the brushless DC motor, the PWM duty ratio r is set to conduct two phases of the three phases, and the PWM duty ratio r is set to conduct two phases of the three phases_postIn particular a functional relation r_post =f (θ，V，T_motorM), wherein the smaller θ is, r_postThe smaller theta is the included angle between the current magnetic field force direction of the stator and the magnetic field direction of the rotor of the brushless direct current motor, V is the current power supply voltage of the brushless direct current motor, and T is the current power supply voltage of the brushless direct current motor_motorM is the current specific temperature of the brushless DC motor and the current load of the brushless DC motorSize; and the spatial direction corresponding to the mode for conducting the two phases in the three phases by the rotor rear positioning control module is separated from the spatial direction corresponding to the mode for conducting the two phases in the three phases in the rotor pre-positioning stage in the starting process of the brushless direct current motor by 0 degree or 60 degrees.

13. A motor controller configured to start, normally operate, and stop a brushless dc motor as required by the control method of the brushless dc motor according to any one of claims 5 to 11, the motor controller comprising: a shutdown control module, a normal control module and a startup control module,

the shutdown control module includes: a stop command generating unit configured to generate a stop command to stop an operation of the brushless dc motor; a free stop control unit configured to stop driving the brushless dc motor until the rotor is stationary according to a stop command of the stop command generating unit; and a rotor rear positioning control unit configured to start operation after the free-stop control unit makes the rotor stationary, and to pull the rotor to a target position by electromagnetic force generated by the stator by conducting two phases of the three phases set in advance, wherein a conducting duration and a PWM duty ratio for conducting two phases of the three phases set in advance are set according to a current specific temperature, a load size and a power supply voltage of the brushless dc motor, and the PWM duty ratio r is set_postIn particular a functional relation r_post =f (θ，V，T_motorM), wherein the smaller θ is, r_postThe smaller theta is the included angle between the current magnetic field force direction of the stator and the magnetic field direction of the rotor of the brushless direct current motor, V is the current power supply voltage of the brushless direct current motor, and T is_motorThe current specific temperature of the brushless direct current motor is obtained, and m is the current load size of the brushless direct current motor; and the space direction corresponding to the mode that the rotor rear positioning control unit conducts two phases of the three phases and the guide in the rotor pre-positioning stage in the starting process of the brushless direct current motorThe spatial directions corresponding to the modes of the two phases in the three phases are separated by 0 degree or 60 degrees;

14. The motor controller of claim 13 wherein said start control module comprises:

a start command generating unit configured to generate a start command to start operation of the brushless DC motor;

a rotor predetermined bit unit configured to take a final rotor stop position of the brushless dc motor after a previous shutdown as a rotor initial position according to the start command, and conduct two phases of the three phases, which are set in advance, according to a deviation between the rotor initial position and a preset fixed rotor position to draw the rotor to the fixed rotor position by an electromagnetic force generated from the stator;

an acceleration unit configured to change a supply voltage or a commutation signal of the brushless dc motor to gradually increase a rotation speed of the brushless dc motor after the rotor pre-positioning unit pulls the rotor to the fixed rotor position; and (c) a second step of,

an operation state switching unit configured to determine a phase change timing of the brushless DC motor by detecting a zero-crossing point of a back electromotive force after the brushless DC motor reaches a required rotation speed by the accelerating unit, so that the brushless DC motor enters a normal operation stage.

15. The motor controller of claim 13, further comprising: the abnormal event monitoring module is configured to monitor whether an abnormal event including motor failure or state locking occurs in real time in the process that the starting control module starts the brushless direct current motor and in the process that the normal control module controls the brushless direct current motor to normally work, and directly trigger the shutdown control module to work once the abnormal event is detected to stop the brushless direct current motor.

16. An electrical device comprising a brushless dc motor, a load and a motor controller according to any one of claims 12 to 15, the motor controller, the brushless dc motor and the load being connected in series.

17. A computer-readable storage medium, on which a computer program is stored, which, when being executed by a processor, carries out a method of stopping a brushless dc motor according to any one of claims 1 to 4, or a method of controlling a brushless dc motor according to any one of claims 5 to 11.