A speed optimization control method and system for a brushless DC motor

Abstract

The present invention relates to the technical field of motor speed control and proposes a brushless DC motor speed optimization control method and system. The method comprises: collecting the rotor angular acceleration, rotor attitude angle, brushless DC motor input current, and brushless DC motor three-phase current to obtain the rotor state vector, input current vector, and current state vector at the current acquisition moment; determining the jitter coefficient and jitter similarity weight at all acquisition moments to determine the jitter evaluation value at the current acquisition moment; collecting the brushless DC motor rotor speed and voltage at the current acquisition moment, and combining the rotor angular acceleration and jitter evaluation value at the current acquisition moment to achieve brushless DC motor speed optimization control. The present invention can solve the problems of abnormal jitter and noise caused by improper brushless DC motor speed control.

Description

Technical Field

[0001] The present invention relates to the technical field of motor speed control, and in particular to a speed optimization control method and system for a brushless DC motor. Background Art

[0002] A brushless DC motor is a high-performance electric motor that significantly reduces friction and noise by using power electronic devices such as transistors to replace the brushes in traditional DC motors for current commutation.

[0003] When optimizing the speed of a brushless DC motor, existing control schemes focus on quickly and accurately adjusting the motor rotor to the target speed, while ignoring motor vibration during acceleration and deceleration. This can easily cause the motor rotor to vibrate significantly during the speed regulation process, causing noise, which will have a negative impact on the life of the brushless DC motor. Summary of the Invention

[0004] The present invention provides a method and system for optimizing the speed control of a brushless DC motor to solve the problems of abnormal jitter and noise caused by improper speed control of the brushless DC motor. The technical solutions adopted are as follows:

[0005] In a first aspect, an embodiment of the present invention provides a method for optimizing the speed control of a brushless DC motor, the method comprising the following steps:

[0006] Collect the rotor's angular acceleration, rotor attitude angle, brushless DC motor input current, and brushless DC motor three-phase current at the current collection moment and a preset time period before the current collection moment, mark the rotor state and current state mark value of the rotor, and obtain the rotor state vector, input current vector, and current state vector at the current collection moment;

[0007] Determine the jitter coefficients for all acquisition moments based on the value of the rotor state in the rotor state vector at the current acquisition moment and the difference between the rotor state in the rotor state vector and the current state flag value at the same acquisition moment in the current state vector;

[0008] Determine the external force variation at each acquisition moment based on the input current vector at the current acquisition moment, determine the jitter similarity weight at each acquisition moment based on the difference between the external force variation at all acquisition moments and the external force variation at the current acquisition moment, and determine the jitter evaluation value at the current acquisition moment based on the jitter similarity weights and jitter coefficients at all acquisition moments;

[0009] The rotor speed and voltage of the brushless DC motor at the current acquisition moment are collected, and the speed optimization control of the brushless DC motor is realized by combining the angular acceleration and jitter evaluation value of the rotor at the current acquisition moment.

[0010] Furthermore, the marking of the rotor state and the obtaining of the rotor state vector at the current acquisition moment include the following specific methods:

[0011] The rotor states with attitude angles greater than or equal to 0° and less than 360° are evenly divided into 6 angle partitions, and each angle partition is marked from 1 to 6 in ascending order;

[0012] Arrange all rotor states in the order of the acquisition moments corresponding to the rotor states to obtain the rotor state vector at the current acquisition moment.

[0013] Furthermore, the method for obtaining the input current vector is:

[0014] Arrange all input currents in the order of the acquisition moments corresponding to the input currents to obtain the input current vector at the current acquisition moment.

[0015] Furthermore, the marking method of the current state marking value and the acquisition method of the current state vector respectively include:

[0016] Determine six current states of the three-phase current corresponding to the angle partitions marked 1-6, and assign current state label values ​​of the six current states to 1-6 in sequence;

[0017] All current state mark values ​​are arranged in the order of the collection moments corresponding to the current state mark values ​​to obtain the current state vector at the current collection moment.

[0018] Furthermore, the jitter coefficients at all acquisition moments are determined based on the value of the rotor state in the rotor state vector at the current acquisition moment, and the difference between the rotor state in the rotor state vector and the current state flag value at the same acquisition moment in the current state vector. The specific method for obtaining the jitter coefficients is as follows:

[0019] Divide adjacent identical rotor states in the rotor state vector at the current acquisition moment into the same group, determine the time interval of the acquisition moments corresponding to all rotor states contained in the same group, divide the current state vector according to the time interval of the group, divide the current state vector into different groups, and obtain the rotor state vector and the corresponding group in the current state vector;

[0020] The number of acquisition moments with different rotor state and current state mark values ​​having the same acquisition moment within the corresponding group of the rotor state vector and the current state vector is recorded as the number of difference moments of the corresponding group of the rotor state vector and the current state vector; the ratio of the number of difference moments of the corresponding group of the rotor state vector and the current state vector to the number of acquisition moments contained in the same group is recorded as the jitter coefficient of all acquisition moments corresponding to the corresponding group of the rotor state vector and the current state vector.

[0021] Furthermore, the method for determining the external force change at the acquisition moment is:

[0022] The input current vector at the current acquisition moment is differentiated with respect to time to obtain the input current derivative vector at the current acquisition moment, and the value contained in the input current derivative vector at the current acquisition moment is recorded as the external force change at the acquisition moment corresponding to the value.

[0023] Furthermore, the method for determining the jitter similarity weight at the acquisition moment is:

[0024] Any acquisition moment is recorded as the target acquisition moment, the absolute value of the difference between the external force change at the target acquisition moment and the current acquisition moment is recorded as the first absolute value of the target acquisition moment, and the normalized value of the reciprocal of the first absolute value of the target acquisition moment is recorded as the jitter similarity weight of the target acquisition moment.

[0025] Furthermore, the jitter evaluation value at the current acquisition moment is determined by:

[0026] The jitter similarity weight at the acquisition moment is used as the weight of the jitter coefficient at the acquisition moment, and the jitter coefficients at all acquisition moments are weighted and summed. The result of the weighted sum is recorded as the jitter evaluation value at the current acquisition moment.

[0027] Furthermore, the above method of combining the rotor angular acceleration and the jitter evaluation value at the current acquisition moment to achieve the speed optimization control of the brushless DC motor includes the following specific methods:

[0028] The product of the rotor angular acceleration and the jitter evaluation value at the current acquisition moment is recorded as the rotor jitter cost at the current acquisition moment;

[0029] When the jitter evaluation value at the current acquisition moment is greater than a first preset threshold, it is determined that the voltage of the brushless DC motor needs to be reduced; when the jitter evaluation value at the current acquisition moment is less than or equal to the first preset threshold, the rotor jitter cost at the current acquisition moment is compared with the second preset threshold. If the rotor jitter cost at the current acquisition moment is greater than the second preset threshold, it is determined that the voltage of the brushless DC motor needs to be increased; if the rotor jitter cost at the current acquisition moment is less than or equal to the second preset threshold, it is determined that the voltage of the brushless DC motor needs to be reduced; the determination results of reducing and increasing the voltage of the brushless DC motor are both recorded as the voltage regulation results of the brushless DC motor;

[0030] If the rotor speed at the current acquisition moment is the same as the preset target speed, the speed of the brushless DC motor is not adjusted;

[0031] If the rotor speed at the current acquisition moment is different from the preset target speed of the rotor, when the voltage adjustment result of the brushless DC motor is to reduce the voltage of the brushless DC motor, the voltage of the brushless DC motor is adjusted to 0.9 times the voltage of the brushless DC motor at the current acquisition moment; when the voltage adjustment result of the brushless DC motor is to increase the voltage of the brushless DC motor, the voltage of the brushless DC motor is adjusted to 1.1 times the voltage of the brushless DC motor at the current acquisition moment;

[0032] At the next acquisition moment after the current acquisition moment, the voltage of the brushless DC motor is adjusted according to the same method as the voltage adjustment of the brushless DC motor at the current acquisition moment, until at a certain adjustment moment, the rotor speed is the same as the preset target speed, and the speed of the brushless DC motor is not adjusted.

[0033] In a second aspect, an embodiment of the present invention further provides a speed optimization control system for a brushless DC motor, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, wherein the processor implements the steps of any one of the above methods when executing the computer program.

[0034] The beneficial effects of the present invention are:

[0035] This application takes into account that during the acceleration and deceleration of the rotor, the rotor state of the brushless DC motor is not completely consistent with the current state corresponding to the input current, causing the brushless DC motor to release energy in the form of heat and friction, resulting in vibration and noise characteristics of the rotor. The degree of consistency between the rotor state vector and the current state vector is evaluated, and the jitter coefficient of all acquisition moments is determined. The jitter coefficient is an evaluation result of the severity of the rotor jitter during acceleration or deceleration; further, the similarity between the rotor state at each acquisition moment and the rotor state at the current acquisition moment is evaluated, and the jitter similarity weight of each acquisition moment is determined. Based on the jitter similarity weights and jitter coefficients of all acquisition moments, the jitter at the current acquisition moment is determined. Evaluation value, in the process of obtaining the jitter evaluation value, it is determined based on all jitter similarity weights and jitter coefficients in the current acquisition moment and the preset time period before the current acquisition moment, which can reduce the inaccuracy of rotor state evaluation caused by measurement errors. At the same time, it avoids the rotor jitter caused by the change of the DC electric force of the rotor, which leads to inaccurate rotor state evaluation; finally, according to the jitter of the brushless DC motor, the voltage of the brushless DC motor is dynamically optimized to realize the speed optimization control of the brushless DC motor, solve the problem of abnormal jitter and noise caused by improper speed control of the brushless DC motor, reduce the jitter in the speed change process of the brushless DC motor, and effectively reduce the jitter wear and rotation noise of the brushless DC motor rotor. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0037] Figure 1 A schematic flow chart of a method for optimizing the speed control of a brushless DC motor provided by one embodiment of the present invention;

[0038] Figure 2 A flowchart of obtaining a jitter coefficient is provided in one embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] See also Figure 1, which shows a flow chart of a speed optimization control method for a brushless DC motor provided by one embodiment of the present invention, the method comprising the following steps:

[0041] Step S001: collect the rotor angular acceleration, rotor attitude angle, brushless DC motor input current and brushless DC motor three-phase current at the current collection moment and a preset time period before the current collection moment, mark the rotor state and current state mark value of the rotor, and obtain the rotor state vector, input current vector and current state vector at the current collection moment.

[0042] A brushless DC motor contains a three-phase inverter bridge circuit. The three phases of the three-phase inverter bridge circuit control the three electromagnets in the motor respectively. The circuit automatically adjusts the current cycle of each phase according to the rotation cycle of the rotor, thereby ensuring that the electromagnet always performs positive work on the rotor and gives the rotor kinetic energy.

[0043] The angular acceleration of the brushless DC motor's rotor is collected using the Hall sensor built into the brushless DC motor.

[0044] The built-in Hall sensor of the brushless DC motor is used to collect the rotor attitude angle at each collection moment.

[0045] It is understood that the rotor attitude angle has a value range of greater than or equal to 0° and less than 360°. The rotor attitude angle represents the clockwise angular difference between the rotor south pole and the electromagnet corresponding to the 0° phase current. For example, when the rotor attitude angle is 0°, the rotor south pole points to the electromagnet corresponding to the 0° phase current.

[0046] According to the attitude angle of the rotor, the rotor state of the rotor is marked, and the rotor state of the attitude angle greater than or equal to 0° and less than 360° is evenly divided into 6 angle partitions, and each angle partition is marked as 1-6 in ascending order. Specifically, the method for marking the rotor state of the rotor is: the rotor state of the attitude angle greater than or equal to 0° and less than 60° is marked as 1, the rotor state of the attitude angle greater than or equal to 60° and less than 120° is marked as 2, the rotor state of the attitude angle greater than or equal to 120° and less than 180° is marked as 3, the rotor state of the attitude angle greater than or equal to 180° and less than 240° is marked as 4, the rotor state of the attitude angle greater than or equal to 240° and less than 300° is marked as 5, and the rotor state of the attitude angle greater than or equal to 300° and less than 360° is marked as 6.

[0047] An ammeter is used to collect the input current of the brushless DC motor at each collection moment.

[0048] The three-phase current of the brushless DC motor is collected using the Hall sensor built into the brushless DC motor. These three-phase currents are the 0° phase current, the 120° phase current, and the 240° phase current. It can be understood that there is a certain restriction relationship between the three-phase currents of the brushless DC motor. Specifically, at any given moment, the three-phase current has three current states: one phase current is positive, one phase current is negative, and the remaining phase current is 0. This certain three-phase current state means that at any given moment, the current of the brushless DC motor flows from one phase to another, and the remaining third phase has no current at this time. Therefore, there are only 6 current states for three-phase current, namely: ①0° phase current is positive, 120° phase current is negative, and 240° phase current is 0; ②0° current is positive, 240° phase current is negative, and 120° phase current is 0; ③120° current is positive, 240° phase current is negative, and 0° phase current is 0; ④120° current is positive, 0° phase current is negative, and 240° phase current is 0; ⑤240° current is positive, 0° phase current is negative, and 120° phase current is 0; ⑥240° current is positive, 120° phase current is negative, and 0° phase current is 0.

[0049] Among them, the six current states ①-⑥ of the three-phase current correspond one-to-one to the six rotor states 1-6. For example, the current state ① of the three-phase current corresponds to the rotor state marked as 1, and the current state ② of the three-phase current corresponds to the rotor state marked as 2.

[0050] According to the values ​​of the three-phase current of the brushless DC motor, the current state mark values ​​of the three-phase current at the time of collection are marked. Specifically, the current state mark values ​​of the six current states of the three-phase current ①-⑥ are assigned values ​​of 1-6 respectively.

[0051] Preferably, in one embodiment of the present application, when collecting angular acceleration, attitude angle, input current, and three-phase current, the data sampling frequency in this embodiment is 1 MHz, and the angular acceleration, attitude angle, input current, and three-phase current are collected at the current collection time and within 10 milliseconds before the current collection time. In actual application, as other implementation methods, implementers can determine the sampling frequency and sampling time based on actual conditions, and this application does not impose any special restrictions.

[0052] Arrange all rotor states in the order of the acquisition moments corresponding to the rotor states to obtain the rotor state vector at the current acquisition moment.

[0053] Arrange all input currents in the order of the acquisition moments corresponding to the input currents to obtain the input current vector at the current acquisition moment.

[0054] All current state mark values ​​are arranged in the order of the collection moments corresponding to the current state mark values ​​to obtain the current state vector at the current collection moment.

[0055] At this point, the rotor state vector, input current vector, and current state vector at the current acquisition moment are obtained.

[0056] Step S002 , determining the jitter coefficients of all acquisition moments respectively according to the value of the rotor state in the rotor state vector at the current acquisition moment and the value difference between the rotor state in the rotor state vector and the current state flag value in the current state vector at the same acquisition moment.

[0057] To control the speed of a brushless DC motor, the DC current input to the motor needs to be gradually increased or decreased. The slower the input current changes, the less jitter and wear the motor experiences during acceleration or deceleration, and the less noise it generates. However, if the input current changes too slowly, the motor's speed will change too slowly, affecting its acceleration performance. Therefore, the current change rate needs to be dynamically adjusted to avoid excessive noise and wear during acceleration or deceleration caused by improper current control.

[0058] When a brushless DC motor is operating stably, the rotor runs at a stable angular velocity while maintaining the same rotor state. Furthermore, the rotor state of the brushless DC motor matches the current state corresponding to the input current. At this point, the direction of the electromagnet's magnetic moment is the same as the direction of the rotor's linear velocity, and the current's efficiency in doing work on the rotor is maximized. However, during rotor acceleration and deceleration, the rotor's speed constantly changes, and the brushless DC motor's control system cannot accurately predict the rotor's speed. This causes the brushless DC motor's rotor state to not completely match the current state corresponding to the input current, resulting in a discrepancy between the direction of the electromagnet's magnetic moment and the direction of the rotor's linear velocity. This in turn reduces the efficiency of the current's work on the rotor. This reduced power releases energy in the form of heat and friction, causing vibration and noise in the rotor.

[0059] Therefore, during the acceleration or deceleration of the rotor, the vibration of the rotor during the acceleration or deceleration process can be judged by the degree of agreement between the rotor state vector and the current state vector.

[0060] The rotor state vectors at the current acquisition moment are grouped according to the values ​​of the rotor states in the rotor state vectors at the current acquisition moment.

[0061] The adjacent identical rotor states in the rotor state vector at the current acquisition moment are divided into the same group, the time interval of the acquisition moment corresponding to all the rotor states contained in the same group is determined, the current state vector is divided according to the time interval of the group, the current state vector is divided into different groups, and the corresponding groups in the rotor state vector and the current state vector are obtained.

[0062] The jitter coefficients of all acquisition moments are determined respectively according to the value differences of the rotor state and current state flag values ​​at the same acquisition moment in the corresponding group in the rotor state vector and the current state vector.

[0063] The number of acquisition moments with different rotor state and current state mark values ​​in the same acquisition moment in the corresponding group of the rotor state vector and the current state vector is recorded as the number of difference moments of the corresponding group in the rotor state vector and the current state vector, and the ratio of the number of difference moments of the corresponding group in the rotor state vector and the current state vector to the number of acquisition moments contained in the same group is recorded as the jitter coefficient of all acquisition moments corresponding to the corresponding group in the rotor state vector and the current state vector.

[0064] For ease of understanding, the following example shows how to obtain the jitter coefficient. When the rotor state vector is 1, 1, 1, 1, 2, 2, 2, 2, 2, 3, 3, 3, 3, and the current state vector is 6, 1, 1, 1, 1, 2, 2, 2, 3, 3, 3, 3, 3, 3, 3, the adjacent identical rotor states in the rotor state vector at the current acquisition moment are divided into the same group. Thus, "1, 1, 1, 1" is the first group, "2, 2, 2, 2, 2" is the second group, and "3, 3, 3, 3" is the third group, for a total of three groups. Based on the time intervals of the acquisition moments corresponding to all rotor states within the three groups divided by the rotor state vector, the rotor state vector should also be divided into three groups. The first group contains the current state tag values ​​corresponding to the first four acquisition moments, the second group contains the current state tag values ​​corresponding to the fifth through ninth acquisition moments, and the first group contains the current state tag values ​​corresponding to the last four acquisition moments. The three groups corresponding to "1, 1, 1, 1," "2, 2, 2, 2, 2," and "3, 3, 3, 3," respectively, are "6, 1, 1, 1," "1, 2, 2, 2, 3," and "3, 3, 3, 3," respectively. For the groups corresponding to the first set of rotor state vectors and current state vectors, the only acquisition moment corresponding to the rotor state and current state tag values ​​within the group that have the same acquisition moment but different values ​​is the first. Therefore, the number of difference moments in this group is 1, and the number of acquisition moments contained in this group is 4. Therefore, the jitter coefficient for all acquisition moments corresponding to this group is 0.25.

[0065] The flow chart for obtaining the jitter coefficient is as follows: Figure 2 shown.

[0066] At this point, the jitter coefficients at all acquisition moments are obtained.

[0067] Step S003: Determine the external force change at each acquisition moment based on the input current vector at the current acquisition moment. Determine the jitter similarity weight at each acquisition moment based on the difference between the external force change at all acquisition moments and the external force change at the current acquisition moment. Determine the jitter evaluation value at the current acquisition moment based on the jitter similarity weights and jitter coefficients at all acquisition moments.

[0068] When the brushless DC motor's rotor rotates at a fixed angular velocity, the power provided by the DC current is equal to the resistance to the rotor's rotation. At this point, the DC current remains constant, and the rotor rotates stably with minimal jitter. However, when the DC current changes, the power provided by the DC current and the resistance to the rotor become unequal, causing the rotor to accelerate or decelerate. If the resultant force of the DC power and the rotor's resistance is not in the direction of the linear velocity, the rotor will jitter, and the greater the resultant force, the more severe the jitter. Therefore, the rotor's jitter is related to the change in the power provided by the current.

[0069] According to the input current vector at the current acquisition moment, the external force variation at each acquisition moment is determined respectively.

[0070] The input current vector at the current acquisition moment is differentiated with respect to time to obtain the input current derivative vector at the current acquisition moment, and the value contained in the input current derivative vector at the current acquisition moment is recorded as the external force change at the acquisition moment corresponding to the value.

[0071] The jitter similarity weight of each acquisition moment is determined according to the difference between the external force variation at all acquisition moments and the external force variation at the current acquisition moment.

[0072] Any acquisition moment is recorded as the target acquisition moment, the absolute value of the difference between the external force change at the target acquisition moment and the current acquisition moment is recorded as the first absolute value of the target acquisition moment, and the normalized value of the reciprocal of the first absolute value of the target acquisition moment is recorded as the jitter similarity weight of the target acquisition moment.

[0073] In the process of calculating the inverse of the first absolute value of the target acquisition moment, the first absolute value of the target acquisition moment needs to be used as the denominator of the fraction. In order to avoid the situation where the denominator is zero, a preset value needs to be added to the denominator. The embodiment of the preset value is 0.01; the purpose of calculating the normalized value is to limit the cumulative sum of the jitter similarity weights of all acquisition moments to a constant 1.

[0074] When the difference between the external force change at the target acquisition moment and the external force change at the current acquisition moment is greater, the jitter similarity weight at the target acquisition moment is greater, the rotor state at the target acquisition moment is more similar to the rotor state at the current acquisition moment, and when determining the rotor state at the current acquisition moment, the reference degree to the rotor state at the target acquisition moment should be greater.

[0075] The jitter similarity weight of each acquisition moment can be obtained in the same way. That is, for any acquisition moment, there is a jitter similarity weight corresponding to it.

[0076] The jitter evaluation value at the current acquisition moment is determined based on the jitter similarity weights and jitter coefficients at all acquisition moments.

[0077] The jitter similarity weight at the acquisition moment is used as the weight of the jitter coefficient at the acquisition moment, and the jitter coefficients at all acquisition moments are weighted and summed. The result of the weighted sum is recorded as the jitter evaluation value at the current acquisition moment.

[0078] The jitter coefficient at the corresponding acquisition moment is weighted according to the jitter similarity weight within 10 milliseconds before the current acquisition moment. This can reduce the inaccuracy of rotor state assessment caused by measurement errors. At the same time, it can avoid the problem of inaccurate rotor state assessment caused by rotor jitter caused by changes in the DC electric force of the rotor.

[0079] At this point, the jitter evaluation value at the current acquisition moment is determined.

[0080] Step S004 : collecting the rotor speed and voltage of the brushless DC motor at the current collection moment, and combining the rotor angular acceleration and the jitter evaluation value at the current collection moment to achieve speed optimization control of the brushless DC motor.

[0081] The rotor jitter cost at the current acquisition moment is determined according to the rotor angular acceleration and the jitter evaluation value at the current acquisition moment.

[0082] The product of the rotor angular acceleration and the jitter evaluation value at the current acquisition moment is recorded as the rotor jitter cost at the current acquisition moment.

[0083] The greater the rotor angular acceleration and the jitter evaluation value at the current acquisition moment, the greater the rotor jitter cost at the current acquisition moment. At this time, the greater the cost of controlling the rotor speed of the brushless DC motor to change.

[0084] When the jitter evaluation value at the current acquisition moment is greater than a first preset threshold, it is determined that the voltage of the brushless DC motor needs to be reduced. When the jitter evaluation value at the current acquisition moment is less than or equal to the first preset threshold, the numerical relationship between the rotor jitter cost at the current acquisition moment and the second preset threshold is compared. If the rotor jitter cost at the current acquisition moment is greater than the second preset threshold, it is determined that the voltage of the brushless DC motor needs to be increased. If the rotor jitter cost at the current acquisition moment is less than or equal to the second preset threshold, it is determined that the voltage of the brushless DC motor needs to be reduced. The results of the determination of reducing and increasing the voltage of the brushless DC motor are both recorded as the voltage regulation results of the brushless DC motor.

[0085] The first preset threshold and the second preset threshold are both preset constant values. In this embodiment, the value of the first preset threshold is 0.1, and the value of the second preset threshold is 10000.

[0086] The brushless DC motor's built-in Hall sensor is used to collect the brushless DC motor's rotor speed and voltage at the current collection time. If the rotor speed at the current collection time is the same as the preset target speed, the brushless DC motor speed is not adjusted. If the rotor speed at the current collection time is different from the preset target speed, the brushless DC motor voltage is adjusted based on the brushless DC motor voltage adjustment result. If the brushless DC motor voltage adjustment result indicates a decrease in the brushless DC motor voltage, the brushless DC motor voltage is adjusted to 0.9 times the brushless DC motor voltage at the current collection time. If the brushless DC motor voltage adjustment result indicates an increase in the brushless DC motor voltage, the brushless DC motor voltage is adjusted to 1.1 times the brushless DC motor voltage at the current collection time.

[0087] At the next acquisition moment after the current acquisition moment, the voltage of the brushless DC motor is adjusted according to the same method as the voltage adjustment of the brushless DC motor at the current acquisition moment, until at a certain adjustment moment, the rotor speed is the same as the preset target speed, and the speed of the brushless DC motor is not adjusted.

[0088] The preset target speed of the rotor is a manually preset value before the brushless DC motor is used, and is set by those skilled in the art according to the use requirements of the brushless DC motor.

[0089] When the voltage of a brushless DC motor changes, the motor's rotor speed also changes. This dynamically optimizes the motor's voltage based on the motor's jitter, achieving speed optimization control and reducing jitter during the motor's speed change process. This effectively minimizes rotor vibration, wear, and rotational noise.

[0090] At this point, the speed optimization control of the brushless DC motor is achieved.

[0091] Based on the same inventive concept as the above method, an embodiment of the present invention also provides a speed optimization control system for a brushless DC motor, including a memory, a processor, and a computer program stored in the memory and running on the processor. When the processor executes the computer program, the steps of any one of the above-mentioned methods for speed optimization control of a brushless DC motor are implemented.

[0092] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for optimizing the speed control of a brushless DC motor, characterized in that: The method comprises the following steps: Collect the rotor angular acceleration, rotor attitude angle, brushless DC motor input current and brushless DC motor three-phase current of the current acquisition moment and a preset time period before the current acquisition moment, mark the rotor state and current state mark value of the rotor, and obtain the rotor state vector, input current vector and current state vector at the current acquisition moment; mark the rotor state of the rotor and obtain the rotor state vector at the current acquisition moment, including the following specific methods: evenly divide the rotor state of the attitude angle greater than or equal to 0° and less than 360° into 6 angle partitions, and mark each angle partition as 1-6 in ascending order; arrange all rotor states in the order of the acquisition moments corresponding to the rotor states, and obtain the rotor state vector at the current acquisition moment; the marking method of the current state mark value and the acquisition method of the current state vector respectively include: determining 6 three-phase current states corresponding to the angle partitions marked 1-6, assigning the current state mark values ​​of the 6 current states to 1-6 in sequence; arrange all current state mark values ​​in the order of the acquisition moments corresponding to the current state mark values, and obtain the current state vector at the current acquisition moment; Determine the jitter coefficients for all acquisition moments based on the value of the rotor state in the rotor state vector at the current acquisition moment and the difference between the rotor state in the rotor state vector and the current state flag value at the same acquisition moment in the current state vector; Based on the input current vector at the current acquisition moment, the external force variation at each acquisition moment is determined. Based on the difference between the external force variation at all acquisition moments and the external force variation at the current acquisition moment, the jitter similarity weight at each acquisition moment is determined. Based on the jitter similarity weights and jitter coefficients at all acquisition moments, the jitter evaluation value at the current acquisition moment is determined. The method for determining the external force variation at the acquisition moment is: The input current vector at the current acquisition moment is differentiated with respect to time to obtain the input current derivative vector at the current acquisition moment, and the value contained in the input current derivative vector at the current acquisition moment is recorded as the external force change at the acquisition moment corresponding to the value; the jitter similarity weight at the acquisition moment is determined by recording any acquisition moment as the target acquisition moment, recording the absolute value of the difference between the external force change at the target acquisition moment and the current acquisition moment as the first absolute value of the target acquisition moment, and recording the normalized value of the reciprocal of the first absolute value of the target acquisition moment as the jitter similarity weight of the target acquisition moment; the jitter evaluation value at the current acquisition moment is determined by using the jitter similarity weight at the acquisition moment as the weight of the jitter coefficient at the acquisition moment, performing weighted summation on the jitter coefficients of all acquisition moments, and recording the result of the weighted summation as the jitter evaluation value at the current acquisition moment; The rotor speed and voltage of the brushless DC motor at the current acquisition moment are collected, and the speed optimization control of the brushless DC motor is realized by combining the angular acceleration and jitter evaluation value of the rotor at the current acquisition moment.

2. The speed optimization control method of a brushless DC motor according to claim 1, characterized in that: The method for obtaining the input current vector is: Arrange all input currents in the order of the acquisition moments corresponding to the input currents to obtain the input current vector at the current acquisition moment.

3. The speed optimization control method of a brushless DC motor according to claim 1, characterized in that: Based on the value of the rotor state in the rotor state vector at the current acquisition moment, and the difference between the rotor state in the rotor state vector and the current state flag value at the same acquisition moment in the current state vector, the jitter coefficients at all acquisition moments are determined. The specific method for obtaining the jitter coefficients is as follows: Divide adjacent identical rotor states in the rotor state vector at the current acquisition moment into the same group, determine the time interval of the acquisition moments corresponding to all rotor states contained in the same group, divide the current state vector according to the time interval of the group, divide the current state vector into different groups, and obtain the rotor state vector and the corresponding group in the current state vector; The number of acquisition moments with different rotor state and current state mark values ​​in the same acquisition moment in the corresponding group of the rotor state vector and the current state vector is recorded as the number of difference moments in the corresponding group of the rotor state vector and the current state vector; the ratio of the number of difference moments in the corresponding group of the rotor state vector and the current state vector to the number of acquisition moments contained in the same group is recorded as the jitter coefficient of all acquisition moments corresponding to the corresponding group of the rotor state vector and the current state vector.

4. The method for optimizing the speed control of a brushless DC motor according to claim 1, wherein: Combined with the rotor angular acceleration and jitter evaluation value at the current acquisition moment, the speed optimization control of the brushless DC motor is achieved, including the following specific methods: The product of the rotor angular acceleration and the jitter evaluation value at the current acquisition moment is recorded as the rotor jitter cost at the current acquisition moment; When the jitter evaluation value at the current acquisition moment is greater than a first preset threshold, it is determined that the voltage of the brushless DC motor needs to be reduced; when the jitter evaluation value at the current acquisition moment is less than or equal to the first preset threshold, the rotor jitter cost at the current acquisition moment is compared with the second preset threshold. If the rotor jitter cost at the current acquisition moment is greater than the second preset threshold, it is determined that the voltage of the brushless DC motor needs to be increased; if the rotor jitter cost at the current acquisition moment is less than or equal to the second preset threshold, it is determined that the voltage of the brushless DC motor needs to be reduced; the determination results of reducing and increasing the voltage of the brushless DC motor are both recorded as the voltage regulation results of the brushless DC motor; If the rotor speed at the current acquisition moment is the same as the preset target speed, the speed of the brushless DC motor is not adjusted; If the rotor speed at the current acquisition moment is different from the preset target speed of the rotor, when the voltage adjustment result of the brushless DC motor is to reduce the voltage of the brushless DC motor, the voltage of the brushless DC motor is adjusted to 0.9 times the voltage of the brushless DC motor at the current acquisition moment; when the voltage adjustment result of the brushless DC motor is to increase the voltage of the brushless DC motor, the voltage of the brushless DC motor is adjusted to 1.1 times the voltage of the brushless DC motor at the current acquisition moment; At the next acquisition moment after the current acquisition moment, the voltage of the brushless DC motor is adjusted according to the same method as the voltage adjustment of the brushless DC motor at the current acquisition moment, until at a certain adjustment moment, the rotor speed is the same as the preset target speed, and the speed of the brushless DC motor is not adjusted.

5. A speed optimization control system for a brushless DC motor, comprising a memory, a processor, and a computer program stored in the memory and running on the processor, characterized in that: When the processor executes the computer program, the steps of the speed optimization control method of the brushless DC motor according to any one of claims 1 to 4 are implemented.

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