CN114465531A

CN114465531A - Control method, system, storage medium and program product for brushless direct current motor

Info

Publication number: CN114465531A
Application number: CN202210184389.4A
Authority: CN
Inventors: 王永禄
Original assignee: Shenzhen Ding Tuo Da Electromechanical Co ltd
Current assignee: Shenzhen Ding Tuo Da Electromechanical Co ltd
Priority date: 2022-02-25
Filing date: 2022-02-25
Publication date: 2022-05-10
Anticipated expiration: 2042-02-25
Also published as: CN114465531B

Abstract

The invention discloses a direct current brushless motor control method, a system, a storage medium and a program product, and relates to the technical field of direct current brushless motor control. The method takes the speed change (beta) of the motor in the last zero-crossing period into account in the time needing delay, and obtains the delay time t with higher precision_{Delay time}And the accuracy of the motor commutation time node calculated by a back electromotive force method is further improved. Due to inertia, the speed change state of the previous zero-crossing period can be applied to the current zero-crossing period to a certain extent, and the invention utilizes the angular acceleration data of the previous zero-crossing period instead of detecting the angular acceleration data of the current zero-crossing period in real time, so that the required data is acquired when the current zero-crossing period is entered, the requirement on the real-time data processing capacity of the control equipment is reduced, and the invention is suitable for more control equipment.

Description

Control method, system, storage medium and program product for brushless direct current motor

Technical Field

The present invention relates to the field of dc brushless motor control technologies, and in particular, to a dc brushless motor control method, system, storage medium, and program product.

Background

The structure of the brushless DC motor is a permanent magnet rotor and a stator (with coils). To operate properly and to maximize efficiency, the stator field must be controlled. In order to control the magnetic field of the stator, the electronic commutator must stably and accurately detect the position of the rotor. There are two main ways to detect the rotor position: 1. detecting by a sensor; 2. and detecting the back electromotive force.

When a plurality of hall sensors are installed according to an electrical angle of 60 degrees, in order to ensure the accuracy, it is required to ensure that mechanical angles between the hall sensors are equally spaced, and it is also required to ensure that the hall sensors are installed at a set position on the motor (that is, a mechanical position where a rotor is located when the motor needs to change phases), and the corresponding hall sensors are generally assembled by reserving corresponding installation grooves on the motor structure. Generally, it is easy to ensure the equal intervals of the mechanical angles among the hall sensors (according to the conversion formula of the mechanical angles and the electrical angles, when the mechanical angles are equally spaced, the electrical angles are equally spaced), but because of the problem of the mechanical precision of the processing equipment, the precision of the mounting groove cannot be ensured, and especially when the stator coils have the problem of incomplete symmetry and the phase change positions are no longer strictly equally spaced, the existing motor control method for detecting the rotor position through the sensors requires technicians to test the asymmetry condition of each motor, and then the motor structure is mechanically processed according to the test results to further adjust the positions of the mounting grooves, which leads to the complicated installation process of the hall sensors.

The problem can be overcome by completely adopting a back electromotive force detection mode to realize the control of motor phase commutation. For example, a scheme for controlling a brushless direct current motor without a position sensor based on a single chip microcomputer is provided by Hu Huan et al^[1]The scheme discloses a starting method and an operation control method of a brushless direct current motor without a position sensor. For example, Linmingyue et al propose a new method for accurately commutation of brushless DC motor based on direct back electromotive force method^[2]In this scheme, a scheme for controlling the commutation time node by a back electromotive force method when there is an asymmetry problem with respect to each stator coil is disclosed. In the above-disclosed scheme for controlling the commutation time node by the back-emf method, the principle is similar, the time passing through two adjacent back-emf zero-crossing points is taken as a zero-point period (i.e. one zero-point period passes through two back-emf zero-crossing points), the time passing through one zero-point period is taken as a reference time, and when the current zero-point period reaches the back-emf zero-crossing point for the first time, half of the reference time (i.e. the time required for delaying pi/6 after considering the back-emf zero-crossing point is taken as half of the reference time) is added to obtain the commutation time nodeAnd (4) a time node of the current commutation (namely, the rotor detected at the current time is considered to be positioned at the commutation position).

However, in some specific application scenarios, the rotation speed of the motor changes constantly, which causes different time lengths corresponding to each zero-point period, so that it is difficult for the existing back electromotive force method to obtain an accurate motor commutation time node.

Reference documents:

[1] bearable, eminence, and pennshun. control of a position-sensorless brushless dc motor [ J ] based on a single-chip microcomputer, motor and control application, 2014(6).

[2] The method is a novel method for accurately commutation of a brushless direct current motor based on a direct back electromotive force method [ J ]. the university of southeast: nature science edition 2010 (1: 6).

Disclosure of Invention

The present invention is directed to solve at least one of the technical problems of the prior art, and provides a method and a system for controlling a brushless dc motor, which take into account the influence of the speed variation on the commutation time node when calculating the commutation time node of the motor by using the back electromotive force method, so as to improve the accuracy of the commutation time node of the motor calculated by using the back electromotive force method.

In order to achieve the purpose, the following technical scheme is provided:

in a first aspect, a method for controlling a dc brushless motor is provided, where the dc brushless motor is in a six-phase state with two phases conducting, and the method includes:

t corresponding to node when back electromotive force zero crossing point is detected_{Get up}Determining t corresponding to the phase change time node of the zero-crossing period according to the formulas (1) and (2)_{Phase change}Time:

t_{phase change}＝t_{Get up}+t_{Delay time} (1)

Wherein from a back emf zero-crossing toThe process of reaching the next adjacent back electromotive force zero crossing point is defined as a zero crossing period; t is t_{Delay time}Represents from t_{Get up}Time begins to t_{Phase change}The delay time of the time, the value of which is meaningful only when the delay time is real and not less than zero; a is a mechanical angle passed by the rotor in the current zero-crossing period; omega₀Is rotor and t_{Get up}Angular velocity corresponding to the moment; beta is the angular acceleration of the rotor in the first N zero-crossing periods adjacent to the current zero-crossing period, and N is a positive integer.

In a second aspect, a dc brushless motor control system is provided, which is applied to a dc brushless motor in a six-phase state where two phases are conducted, and the system includes:

a phase change time determining module for determining t corresponding to the node when the counter electromotive force zero crossing point is detected_{Get up}Determining t corresponding to the phase change time node of the zero-crossing period according to the formulas (1) and (2)_{Phase change}Time:

t_{phase change}＝t_{Get up}+t_{Delay time} (1)

Defining a process from one back electromotive force zero-crossing point to the next adjacent back electromotive force zero-crossing point as a zero-crossing period; t is t_{Delay time}Represents from t_{Get up}Time begins to t_{Phase change}The delay time of the time, the value of which is meaningful only when the delay time is real and not less than zero; a is a mechanical angle passed by the rotor in the current zero-crossing period; omega₀Is rotor and t_{Get up}Angular velocity corresponding to the moment; beta is the angular acceleration of the rotor in the first N zero-crossing periods adjacent to the current zero-crossing period, and N is a positive integer.

In a third aspect, embodiments of the present invention provide a computer program product, which includes computer programs/instructions, when executed by a processor, for implementing the steps of a dc brushless motor control method described in any one of the above.

In a fourth aspect, embodiments of the present invention provide a computer-readable storage medium storing computer-executable instructions for causing a computer to perform a dc brushless motor control method according to any one of the embodiments of the first aspect of the present invention.

The invention provides a control method, a system, a storage medium and a program product of a brushless DC motor, compared with the prior art, t corresponding to a phase change time node of the current zero-crossing period_{Phase change}The moment is only t corresponding to the zero-crossing period_{Get up}The time is delayed by half of the last zero-crossing period, so that the problem that the accuracy of a motor commutation time node is not high under the scene that the speed of a motor rotor changes frequently is caused. The invention provides a control method of a brushless direct current motor, which takes the speed change (beta) of the motor in the last zero-crossing period into consideration of the time needing to be delayed and obtains the delay time t with higher precision_{Delay time}And the accuracy of the motor commutation time node calculated by a back electromotive force method is further improved. Due to inertia, the speed change state of the previous zero-crossing period can be applied to the current zero-crossing period to a certain extent, and the invention utilizes the angular acceleration data of the previous zero-crossing period instead of detecting the angular acceleration data of the current zero-crossing period in real time, so that the required data is acquired when the current zero-crossing period is entered, the requirement on the real-time data processing capacity of the control equipment is reduced, and the invention is suitable for more control equipment.

Additional aspects and advantages of the invention will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the invention.

Drawings

The invention is further described below with reference to the accompanying drawings and examples;

fig. 1 is a block diagram of a dc brushless motor control system according to an embodiment.

Fig. 2 is a schematic diagram illustrating a control method of the dc brushless motor according to an embodiment.

Fig. 3 is a schematic diagram illustrating a control method of the dc brushless motor according to an embodiment.

Fig. 4 is a schematic diagram illustrating a control method of the dc brushless motor according to an embodiment.

Fig. 5 is a schematic diagram illustrating a control method of the dc brushless motor according to an embodiment.

Fig. 6 is a schematic diagram illustrating a control method of the dc brushless motor according to an embodiment.

Detailed Description

Reference will now be made in detail to the present preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout.

Fig. 1 is a block diagram of a dc brushless motor control system according to an embodiment. Referring to fig. 1, a dc brushless motor control method is applied to a dc brushless motor control system. The direct current brushless motor control system comprises a control unit, a driving unit, a detection unit and a power supply unit; the DC brushless motor control system is electrically connected with the DC brushless motor in a two-phase conduction three-phase six-state and is used for driving and controlling the motor to work. The control unit is composed of a control signal processor, a PID (proportion integration differentiation) and a current controller which are shown by a dotted line frame in figure 1 and is used for processing the acquired signals and sending signals for controlling the starting and running of the motor to the driving unit; the power supply unit comprises a direct current power supply and is used for supplying power to the driving unit and the control unit; the driving unit comprises an inversion module and an overcurrent protection module, wherein the inversion module is used for converting a direct current signal into a pulse signal for driving the motor to act; the detection unit comprises a back electromotive force detection circuit and a sensor detection circuit, wherein the sensor detection circuit is used as an improved point of the invention and comprises a motor according to the following steps

The mechanical angle of the sensor is provided with 6 Hall sensors at equal intervals,compared with the prior art, the motor phase-changing device has the advantages that the mechanical angle between every two Hall sensors is required to be equal, the set position (namely the mechanical position of the rotor when the motor needs to change the phase) of each Hall sensor on the motor is required to be ensured, and the motor processing difficulty is large, and the assembly process is complicated. According to the scheme provided by the embodiment, the 6 Hall sensors are installed at equal mechanical angle intervals, so that whether the stator coils are symmetrical or not is not required to be tested firstly when the Hall sensors are assembled, the processing difficulty of the motor is reduced, and the assembling process of the Hall sensors is simplified.

Hereinafter, the dc brushless motor control method provided by the embodiment of the present invention will be described and explained in detail by several specific embodiments.

In one embodiment, a dc brushless motor control method is provided, which is applied to a dc brushless motor in a two-phase conduction three-phase six-state. The method comprises the following steps:

t_{phase change}＝t_{Get up}+t_{Delay time} (1)

Defining a process from one back electromotive force zero-crossing point to the next adjacent back electromotive force zero-crossing point as a zero-crossing period; t is t_{Delay time}Denotes from t_{Get up}Time begins to t_{Phase change}The delay time of the time, the value of which is meaningful only when the delay time is real and not less than zero; a is a mechanical angle passed by the rotor in the current zero-crossing period; omega₀Is rotor and t_{Get up}Angular velocity corresponding to the moment; beta is the angular acceleration of the rotor in the first N zero-crossing periods adjacent to the current zero-crossing period, and N is a positive integer.

It can be understood that in the prior artE.g. in literature [1]And document [2]]Shown as t corresponding to the phase change time node of the zero-crossing period_{Phase change}The moment is only t corresponding to the zero-crossing period_{Get up}The time is delayed by half of the last zero-crossing period, so that the problem that the accuracy of a motor commutation time node is not high under the scene that the speed of a motor rotor changes frequently is caused. The reason for this is as shown in fig. 2, assuming that the equal interval between each two adjacent back electromotive force zero-crossing points is 60 ° in electrical angle, and the current back electromotive force zero-crossing point time, the rotor is at the O point position in fig. 2, in an ideal case, it is considered that when the current back electromotive force zero-crossing point time is delayed by half of the last zero-crossing period time, the rotor should reach the P2 position (α is 30 °), that is, reach the 30 ° phase angle position, and at this time, the phase commutation table is looked up to control the motor to perform phase commutation, which is the method adopted in document 1. However, in a practical application scenario of the motor, it often occurs that when the time is delayed by half of the time of the previous zero-crossing period from the current zero-crossing time of the back electromotive force, the rotor is at the position of P1 or P3, and the reasons include that the rotation speed of the motor is actively controlled by a user during the operation of the motor and the rotation speed of the rotor is changed by an external force applied to the output shaft of the motor, in addition to the reason that the stator winding is not symmetrical mentioned in document 2. For example, when a user actively adjusts the rotation speed, the rotation speed of the rotor in the current zero-crossing period and the rotation speed of the rotor in the previous zero-crossing period may be different, and in a system of rotational motion constituted by the rotors, when the angular acceleration is different, the rotation angles in the same time period are also different. Based on the principle, when the speed change condition exists, in order to accurately delay the phase angle of 30 degrees, the embodiment constructs the relation between the angular acceleration and the rotor rotation sweep angle into the formula (2), and can accurately calculate the time t required for delaying the phase angle of 30 degrees after reaching the counter electromotive force zero crossing point under the condition of the change of the rotor speed_{Delay time}. It can be known that, in the dc brushless motor in the two-phase conduction three-phase six-state, after reaching the back electromotive force zero crossing point, it is necessary to perform phase commutation at a phase angle of 30 °, and according to the conversion relationship between the mechanical angle and the electrical angle: the electric angle is equal to the mechanical angle multiplied by the pole pair number, the electric angle is in direct proportion to the mechanical angle, and for a two-pole motor, the inner circle of a stator of the two-pole motorThe electrical angle and the mechanical angle are equal and are both 360 degrees. For ease of understanding, taking a two-pole motor as an example, which requires the rotor to rotate through a phase angle of 30 ° after reaching the back emf zero-crossing, the electrical angle the rotor rotates through is the same for each zero-crossing period, and the mechanical angle the rotor rotates through is the same for each zero-crossing period. A delay of 30 ° phase angle (electrical angle) which is half of the electrical angle passed by one zero-crossing period is required in the back electromotive force method; similarly, at the commutation position, half of the mechanical angle of the rotor passing through a zero-crossing period is also calculated, that is, the time of half of the mechanical angle of the rotor reaching the zero-crossing period after reaching the back electromotive force zero-crossing point is actually calculated in formula (2), and the time is t_{Delay time}The time t_{Delay time}Is determined by equation (2) constructed from the relationship between angular acceleration β and rotor rotation sweep angle a. It can be understood that a is a mechanical angle that the rotor passes through in the current zero-crossing period, and in this embodiment, the mechanical angles that the respective zero-crossing periods pass through are the same.

The invention provides a control method of a brushless direct current motor, which takes the speed change (beta) of the motor in the last zero-crossing period into consideration of the time needing to be delayed and obtains the delay time t with higher precision_{Delay time}And the accuracy of the motor commutation time node calculated by a back electromotive force method is further improved. Due to inertia, the speed change state of the previous zero-crossing period can be applied to the current zero-crossing period to a certain extent, and the invention utilizes the angular acceleration data of the previous zero-crossing period instead of detecting the angular acceleration data of the current zero-crossing period in real time, so that the required data is acquired when the current zero-crossing period is entered, the requirement on the real-time data processing capacity of the control equipment is reduced, and the invention is suitable for more control equipment.

In one embodiment, the motor outputs a pulse signal with the frequency f to control the rotating speed of the rotor by the inverter module; the method further comprises the following steps:

determining ω from equations (3) and (4)₀And β:

β＝ω_j-1-ω_j-2 (4)

wherein j is a positive integer and represents a zero-crossing period with the serial number j; f. of_jRepresenting the frequency of the pulse signal output by the inverter module in the zero-crossing period with the sequence number j; p represents the number of pole pairs of the motor; omega_j-1Representing the angular velocity of the rotor during the zero-crossing period numbered j-1; omega_j-2Representing the angular velocity of the rotor in the zero-crossing period of sequence number j-2.

In this embodiment, the sequence number of the zero-crossing period is j, and t corresponding to the back electromotive force zero-crossing time node is detected_{Get up}The starting time of the zero-crossing period with the time sequence number j needs to be delayed by t_{Delay time}After t_{Phase change}And carrying out phase change at any moment. At the moment, the output frequency is f according to the inversion module_jPulse signal, and ω is calculated by the formula (3)₀The angular velocity at the initial time in the zero-crossing period with the sequence number j-2 is taken as ω_j-2The angular velocity at the initial time in the zero-crossing period with the sequence number j-1 is taken as ω_j-1In the case of a two-pole motor,

substituting into formulas (1) and (2) to calculate corresponding t_{Phase change}The time of day.

In the embodiment, the speed change condition of the rotor is calculated by using the frequency of the output signal of the inversion module for controlling the rotating speed of the motor, the frequency data can be obtained through the control unit, other sensors are not required to be additionally installed, namely, the original structure of the motor is not required to be changed, so that the method disclosed by the invention has strong applicability to motors with different structures and has good universality.

In one embodiment, the motor is provided with a motor according to

The mechanical angle of the sensor is provided with 6 Hall sensors at equal intervals; the method further comprises the following steps:

according to the formula(5) And (6) determining ω₀And β:

wherein i is a positive integer and represents a zero-crossing period with the serial number i; t is t_iDenotes the moment at which the Hall sensor detects the trigger signal in the zero-crossing period with the sequence number i, t_i-1Denotes the moment at which the Hall sensor detects the trigger signal in the zero-crossing period with the sequence number i-1, t_i-2And the moment when the Hall sensor detects the trigger signal in the zero-crossing period with the serial number of i-2 is shown, and the rotor sequentially triggers the corresponding Hall sensors in each zero-crossing period according to the sequence from small to large of the serial numbers.

It will be appreciated that 6 hall sensors are provided on the motor according to

The mechanical angles are installed at equal intervals, so that the condition that a plurality of Hall sensors are simultaneously triggered at each zero-crossing period exists, and the invention determines whether the rotor rotates through the counting of the coding signal rule formed by the Hall sensors with the numbers by numbering the Hall sensors

Time node of the mechanical angle of (1). As shown in fig. 3, taking a two-pole motor as an example, the numbers of the 6 hall sensors in the counterclockwise direction are W1, W2, W3, W4, W5 and W6, and when the 6 hall sensors are not triggered, the signal codes are 000000; if the hall sensors are unipolar hall sensors, as shown in fig. 3, at the current time t1, the rotor just rotates to the positions where W2 and W5 are triggered, and then signals output by the 6 hall sensors are encoded to obtain encoded signals 010010; as shown in fig. 4, at the present time t2, the rotor has just rotated to the position where W3 and W6 are triggered,encoding the signals output by the 6 Hall sensors to obtain encoded signals of 001001; it can be seen that when the coded signal is switched from 010010 to 001001, the rotor passes

When the hall sensors detect the trigger signals, the trigger signals are the corresponding coded signals detected by 6 hall sensors, i.e. the hall sensors detect the trigger signals in two adjacent zero-crossing periods, respectively, t1 and t 2. By analogy, all possible coded signals in the motor can be obtained, and the rotor passing through each motor can be obtained by analyzing according to the motor structure and the installation position of the Hall sensor

Corresponding code signal (i.e. corresponding trigger signal) at the mechanical angle of (a) to count the number of times the rotor passes each time

The mechanical angle of (c).

As shown in fig. 5, the circle represents a time occupancy distribution diagram corresponding to six zero-crossing periods that are adjacent in sequence in one embodiment, an arc edge of each sector corresponds to a time length corresponding to one zero-crossing period, a black dot on an edge of each sector represents a time when the hall sensor detects a trigger signal in the zero-crossing period, a zero-crossing period with a serial number i-2, a zero-crossing period with a serial number i-1, a zero-crossing period with a serial number i, and a zero-crossing period with a serial number i +1 are shown in a clockwise direction, and two endpoints of the arc edge are back electromotive force zero-crossing points. It can be known that, although the hall sensors are installed at equal intervals in the present embodiment, the hall sensors do not need to be exactly aligned with the corresponding back electromotive force zero-crossing positions (i.e., the hall sensors are required to be triggered when the back electromotive force zero-crossing points occur).

Therefore, in this embodiment, the sequence number of the current zero-crossing period is i +1, and t corresponding to the back electromotive force zero-crossing time node is detected_{Get up}The time is the starting time of the zero-crossing period with the sequence number i +1 and needs to be delayed by t_{Delay time}After t_{Phase change}And carrying out phase change at all times. At this time, according to equation (5), ω is calculated from the last zero-crossing period of the zero-crossing period with the serial number i +1 (i.e., the zero-crossing period with the serial number i) and the last zero-crossing period of the zero-crossing period with the serial number i (i.e., the zero-crossing period with the serial number i-1)₀I.e. consider the rotor at t_{Get up}The angular velocity corresponding to the time is the angular velocity of the last zero-crossing period. Then, in determining β according to equation (6), in a two-pole motor,

substituting into formulas (1) and (2) to calculate corresponding t_{Phase change}The time of day. It should be noted that, in this embodiment, it is not necessary to ensure that each hall sensor is strictly aligned with the back electromotive force zero-crossing position, and the installation is simpler and more convenient.

Compared with the prior art, the hall sensors are arranged on the motor, so that the mechanical angle of a distance between every two hall sensors is required to be equal, and the set position (namely the mechanical position of the rotor when the motor needs to change phases) of each hall sensor arranged on the motor is required to be ensured, so that the motor is high in processing difficulty and complicated in assembly process. According to the scheme provided by the embodiment, the 6 Hall sensors are installed at equal mechanical angle intervals, so that whether the stator coils are symmetrical or not is not required to be tested firstly when the Hall sensors are assembled, the processing difficulty of the motor is reduced, and the assembling process of the Hall sensors is simplified. Meanwhile, in the embodiment, the speed change of the motor in the first zero-crossing periods can be acquired in real time by using the Hall sensor, so that the speed change (beta) of the motor in the first zero-crossing periods is considered in the time needing to be delayed, the delay time with higher precision is acquired, and the accuracy of the phase change time node of the motor calculated by a back electromotive force method is improved. Compared with a method for determining the real-time rotating speed of the motor according to the frequency output by the inverter module, the method for measuring the rotating speed of the motor through the Hall sensor has higher precision when external disturbance exists in the running environment of the motor. If the speed of the motor rotor is inconsistent with the frequency output by the inverter module due to frequent change of the motor load, the method for detecting the rotating speed through the hall sensor provided by the embodiment can obtain the accurate rotating speed change condition, and has higher precision.

In one embodiment, the method further comprises:

keeping the rotor running in a constant-speed rotation state, and determining basic mechanical angles R corresponding to 6 zero-crossing periods which are adjacent in sequence according to a formula (7)_k；

Wherein k represents a zero-crossing period with the serial number k; t is_kRepresenting the duration of the rotor in a zero-crossing period with the sequence number k;

determining a mechanical angle A corresponding to a zero-crossing period with the sequence number x according to a formula (8);

A＝R_xmod6 (8)

wherein x is an integer greater than 5.

As shown in fig. 6, the circle represents a time occupancy distribution diagram corresponding to six zero-crossing periods that are adjacent in sequence in one embodiment, each arc edge of each sector corresponds to a time length corresponding to one zero-crossing period, a black dot on each sector edge represents a time when the hall sensor detects a trigger signal in the zero-crossing period, a zero-crossing period with a serial number i-2, a zero-crossing period with a serial number i-1, a zero-crossing period with a serial number i, and a zero-crossing period with a serial number i +1 are shown in a clockwise direction, two end points of each arc edge are back electromotive force zero-crossing points, and a length of each arc edge represents a time length of the zero-crossing period. In fig. 6, the electrical angle corresponding to the zero-crossing period with the serial number i is greater than 60 °, and the electrical angle corresponding to the zero-crossing period with the serial number i +1 is less than 60 °. As can be seen from the above equations (7) and (8), the zero-crossing period with the number i +6 is the same as the electrical angle corresponding to the zero-crossing period with the number i.

In the embodiment, it is considered that the electrical angles corresponding to the zero-crossing periods are different due to the asymmetry of the stator coil caused by the processing and assembling precision of the motor in the prior art, so that the half time according to the last zero-crossing period is causedTo determine t corresponding to the phase change time node corresponding to the zero-crossing period_{Phase change}The moment has the problem of inaccuracy. In this embodiment, the basic mechanical angle corresponding to each zero-crossing period is accurately detected, and the basic mechanical angles R corresponding to 6 sequentially adjacent zero-crossing periods are found_kI.e. two zero-crossing cycles separated by 360 mechanical degrees have the same mechanical angle a. Therefore, whether the motor is asymmetric or not can be detected through the embodiment, the mechanical angle A in the formula (2) can be ensured to be more accurate, and the delay time t with higher precision is obtained_{Delay time}And the accuracy of the motor commutation time node calculated by a back electromotive force method is further improved.

In one embodiment, the method further comprises:

the motor is applied to the electric vehicle, an acceleration sensor or a level meter is arranged on the electric vehicle, when the number of times that the angle variation amplitude of the electric vehicle is larger than the threshold angle in a preset time period is less than a set number of times according to the acceleration sensor or the level meter, the electric vehicle is judged to be driven on a flat road condition, and omega is determined according to formulas (3) and (4)₀And beta;

the motor is applied to the electric vehicle, an acceleration sensor or a level meter is arranged on the electric vehicle, when the times that the change amplitude of the angle is larger than the threshold angle within the preset time period detected by the acceleration sensor or the level meter is more than the set times, and the electric vehicle is judged to be running on the rugged road condition, omega is determined according to the formulas (5) and (6)₀And beta.

Considering that when the electric vehicle runs on a flat road condition, because the influence of the external road action force on the motor rotor is small, omega is determined only according to the frequency of the output signal of the inversion module₀And beta can obtain high enough precision, and the frequency data can be obtained from the inversion module only at the moment, and because the frequency of the output signal of the inversion module is set by the control device, compared with the data obtained by a sensor mode, the control device can quickly obtain the frequency data without interruption in the embodiment, and the calculation speed is higher. When the electric vehicle is in rugged road conditionDuring the process, through the parameters set by test data (for example, the times that the angle variation amplitude in unit time is greater than the threshold value, for example, the times that the angle variation amplitude in 20 seconds is greater than 20 degrees and the times reach 10 times), it can be known that the rotation of the electronic rotor is influenced by the severe external acting force of the motor at the moment, and at the moment, the omega is determined only by the frequency of the output signal of the inverter module₀And β has not been able to achieve sufficient accuracy, it is necessary to switch to a more accurate way to obtain the corresponding ω₀And beta. To sum up, the embodiment provides a method capable of automatically switching to obtain ω according to the driving road condition of the electric vehicle₀And the method of the beta mode can further improve the accuracy of the motor commutation time node calculated by the back electromotive force method.

In another aspect, in an embodiment, there is provided a dc brushless motor control system applied to a dc brushless motor in a two-phase conduction three-phase six-state, the system including:

a phase change time determining module for determining t corresponding to the node when the counter electromotive force zero crossing point is detected_CraneDetermining t corresponding to the phase change time node of the zero-crossing period according to the formulas (1) and (2)_{Phase change}Time:

t_{phase change}＝t_Crane+t_{Delay time} (1)

Defining a process from one back electromotive force zero-crossing point to the next adjacent back electromotive force zero-crossing point as a zero-crossing period; t is t_{Delay pipe}Represents from t_{Get up}Time of day start to t_{Phase change}The delay time of the time, the value of which is meaningful only when the delay time is real and not less than zero; a is a mechanical angle passed by the rotor in the current zero-crossing period; omega₀Is rotor and t_{Get up}Angular velocity corresponding to the moment; beta is the angular acceleration of the rotor in the first N zero-crossing periods adjacent to the current zero-crossing period, and N is a positive integer.

In one embodiment, the motor outputs a pulse signal with the frequency f to control the rotating speed of the rotor by the inverter module; the system further comprises:

a first speed change information determination module for determining ω according to equations (3) and (4)₀And β:

β＝ω_j-1-ω_j-2 (4)

wherein j is a positive integer and represents a zero-crossing period with the serial number j; f. of_jRepresenting the frequency of the pulse signal output by the inverter module in the zero-crossing period with the sequence number j; p represents the number of pole pairs of the motor; omega_j-1Representing the angular velocity of the rotor during the zero-crossing period numbered j-1; omega_j-2Representing the angular velocity of the rotor during the zero-crossing period numbered j-2.

In one embodiment, the motor is provided with a motor according to

The mechanical angle of the sensor is provided with 6 Hall sensors at equal intervals; the system further comprises:

a second speed variation information determination module for determining ω according to equations (5) and (6)₀And β:

wherein i is a positive integer and represents a zero-crossing period with the serial number i; t is t_iDenotes the moment at which the Hall sensor detects the trigger signal in the zero-crossing period with the sequence number i, t_i-1Denotes the moment at which the Hall sensor detects the trigger signal in the zero-crossing period with the sequence number i-1, t_i-2Indicating detection by the hall sensor in the zero-crossing period of sequence number i-2And at the moment of triggering the signals, the rotor sequentially triggers the corresponding Hall sensors in each zero-crossing period according to the sequence of the sequence numbers from small to large.

In one embodiment, the system further comprises:

the basic mechanical angle determining module is used for keeping the rotor to operate in a constant-speed rotation state and determining basic mechanical angles R corresponding to 6 sequentially adjacent zero-crossing periods according to a formula (7)_k；

the mechanical angle determining module is used for determining a mechanical angle A corresponding to a zero-crossing period with the sequence number x according to a formula (8);

A＝R_xmod6 (8)

wherein x is an integer greater than 5.

It should be noted that, since the system embodiment and the method embodiment of the present invention are based on the same inventive concept, they are not described herein again.

In one embodiment, a computer-readable storage medium is provided, which stores computer-executable instructions for causing a computer to perform the steps of a dc brushless motor control method described above. The steps of a dc brushless motor control method herein may be the steps of a dc brushless motor control method in each of the above embodiments.

In one embodiment, a computer program product is provided comprising computer programs/instructions which, when executed by a processor, implement the steps of a dc brushless motor control method as described in any one of the above.

It will be understood by those skilled in the art that all or part of the processes of the methods of the embodiments described above can be implemented by a computer program, which can be stored in a non-volatile computer-readable storage medium, and can include the processes of the embodiments of the methods described above when the program is executed. Any reference to memory, storage, database, or other medium used in the embodiments provided herein may include non-volatile and/or volatile memory, among others. Non-volatile memory can include read-only memory (ROM), Programmable ROM (PROM), Electrically Programmable ROM (EPROM), Electrically Erasable Programmable ROM (EEPROM), or flash memory. Volatile memory can include Random Access Memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in a variety of forms such as Static RAM (SRAM), Dynamic RAM (DRAM), Synchronous DRAM (SDRAM), Double Data Rate SDRAM (DDRSDRAM), Enhanced SDRAM (ESDRAM), synchronous Link (Synchlink) DRAM (SLDRA), Rambus Direct RAM (RDRA), direct memory bus dynamic RAM (DRDRAM), and memory bus dynamic RAM (RDRAM).

The technical features of the above embodiments can be arbitrarily combined, and for the sake of brevity, all possible combinations of the technical features in the above embodiments are not described, but should be considered as the scope of the present specification as long as there is no contradiction between the combinations of the technical features.

Claims

1. A control method of a brushless DC motor is applied to the brushless DC motor in a six-state of two-phase conduction and three-phase conduction, and is characterized by comprising the following steps:

t_{phase change}＝t_{Get up}+t_{Delay time} (1)

Wherein the content of the first and second substances,defining a process of reaching a next adjacent back electromotive force zero-crossing point from one back electromotive force zero-crossing point as a zero-crossing period; t is t_{Delay time}Represents from t_{Get up}Time begins to t_{Phase change}The delay time of the time, the value of which is meaningful only when the delay time is real and not less than zero; a is a mechanical angle passed by the rotor in the current zero-crossing period; omega₀Is the rotor and t_{Get up}Angular velocity corresponding to the moment; beta is the angular acceleration of the rotor in the first N zero-crossing periods adjacent to the current zero-crossing period, and N is a positive integer.

2. The method according to claim 1, wherein the inverter module outputs a pulse signal with a frequency of f to control the rotation speed of the rotor; the method further comprises the following steps:

determining ω from equations (3) and (4)₀And β:

β＝ω_j-1-ω_j-2 (4)

3. A method according to claim 1, wherein said motor is arranged in accordance with

determining ω from equations (5) and (6)₀And β:

4. The method of claim 1, further comprising:

Wherein k represents a zero-crossing period with the serial number k; t is a unit of_kRepresenting the duration of the rotor in a zero-crossing period with the sequence number k;

A＝R_xmod6 (8)

wherein x is an integer greater than 5.

5. A DC brushless motor control system, which is applied to a DC brushless motor in a two-phase conduction three-phase six-state, and is characterized in that the system comprises:

t_{phase change}＝t_{Get up}+t_{Delay time} (1)

Defining a process from one back electromotive force zero-crossing point to the next adjacent back electromotive force zero-crossing point as a zero-crossing period; t is t_{Delay pipe}Represents from t_{Get up}Time begins to t_{Phase change}The delay time experienced by a time of day, the value of which is meaningful only when it is real and not less than zero; a is a mechanical angle passed by the rotor in the current zero-crossing period; omega₀Is rotor and t_{Get up}Angular velocity corresponding to the moment; beta is the angular acceleration of the rotor in the first N zero-crossing periods adjacent to the current zero-crossing period, and N is a positive integer.

6. The DC brushless motor control system according to claim 5, wherein the motor outputs a pulse signal with a frequency f to control the rotation speed of the rotor; the system further comprises:

β＝ω_j-1-ω_j-2 (4)

wherein j is a positive integer and represents a zero-crossing period with the serial number j; f. of_jRepresenting the frequency of the pulse signal output by the inverter module in the zero-crossing period with the sequence number j; p denotes an electric machineThe number of pole pairs of; omega_j-1Representing the angular velocity of the rotor during the zero-crossing period numbered j-1; omega_j-2Representing the angular velocity of the rotor during the zero-crossing period numbered j-2.

7. A brushless DC motor control system according to claim 5, characterized in that the motor is arranged according to

8. A brushless DC motor control system according to claim 5, further comprising:

the basic mechanical angle determining module is used for keeping the rotor to operate in a constant-speed rotating state and determining basic mechanical angles R corresponding to 6 sequentially adjacent zero-crossing periods according to a formula (7)_k；

A＝R_{x mod6} (8)

wherein x is an integer greater than 5.

9. A computer-readable storage medium storing computer-executable instructions for causing a computer to perform a dc brushless motor control method according to any one of claims 1 to 4.

10. A computer program product comprising computer programs/instructions, characterized in that the computer programs/instructions, when executed by a processor, implement the steps of a dc brushless motor control method according to any of claims 1 to 4.