Rotating speed optimization control method and system of brushless direct current motor

Abstract

The invention relates to the technical field of motor rotating speed control, and provides a rotating speed optimization control method and system for a brushless direct current motor, and the method comprises the steps: collecting the angular acceleration of a rotor, the attitude angle of the rotor, the input current of the brushless direct current motor, and the three-phase current of the brushless direct current motor; acquiring a rotor state vector, an input current vector and a current state vector at the current acquisition moment; respectively determining jitter coefficients and jitter similar weights at all acquisition moments, and determining a jitter evaluation value at the current acquisition moment; and acquiring the rotating speed and voltage of the rotor of the brushless direct current motor at the current acquisition moment, and realizing rotating speed optimization control of the brushless direct current motor by combining the angular acceleration and the jitter evaluation value of the rotor at the current acquisition moment. The problems of abnormal jitter and noise caused by improper rotating speed control of the brushless direct current motor can be solved.

Description

Technical Field

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

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

[0003] When optimizing the speed control of a brushless DC motor, the purpose of existing control schemes focuses on accurately and quickly adjusting the motor rotor to the target speed, while ignoring the motor jitter during the acceleration and deceleration processes. This easily causes the motor rotor to experience significant jitter during speed regulation, generating noise, which will have an adverse effect on the lifespan 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 specific technical solutions adopted are as follows: 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: Collect the angular acceleration of the rotor, the attitude angle of the rotor, the input current of the brushless DC motor, and the three-phase current of the brushless DC motor at the current acquisition moment and within a preset time period before the current acquisition moment, mark the rotor state and the current state marking value of the rotor, and obtain the rotor state vector, the input current vector, and the current state vector at the current acquisition moment; 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 marking value at the same acquisition moment in the current state vector, respectively determine the jitter coefficients at all acquisition moments; According to the input current vector at the current acquisition moment, respectively determine the external force change amount at each acquisition moment. According to the difference between the external force change amounts at all acquisition moments and the external force change amount at the current acquisition moment, respectively determine the jitter similarity weights at each acquisition moment. According to the jitter similarity weights and jitter coefficients at all acquisition moments, determine the jitter evaluation value at the current acquisition moment; Collect the rotor speed and voltage of the brushless DC motor at the current acquisition moment, and combine the angular acceleration of the rotor and the jitter evaluation value at the current acquisition moment to achieve the optimized speed control of the brushless DC motor.

[0005] Further, the method for marking the rotor state of the rotor and obtaining the rotor state vector at the current acquisition moment specifically includes: The rotor states with attitude angles greater than or equal to 0° and less than 360° are evenly divided into 6 angular partitions, and the angular partitions are respectively marked as 1 - 6 in ascending order; All rotor states are arranged in the order of the acquisition times corresponding to the rotor states to obtain the rotor state vector at the current acquisition time.

[0006] Furthermore, the method for obtaining the input current vector is as follows: All input currents are arranged in the order of the acquisition times corresponding to the input currents to obtain the input current vector at the current acquisition time.

[0007] Furthermore, the marking method of the current state marking value and the method for obtaining the current state vector respectively include: Determine 6 current states of three-phase current corresponding one-to-one to the angular partitions marked as 1 - 6, and assign the current state marking values of the 6 current states as 1 - 6 in sequence; All current state marking values are arranged in the order of the acquisition times corresponding to the current state marking values to obtain the current state vector at the current acquisition time.

[0008] Furthermore, the specific method for respectively determining the jitter coefficients at all acquisition times according to the values of the rotor states in the rotor state vector at the current acquisition time and the value differences between the rotor states in the rotor state vector and the current state marking values at the same acquisition time in the current state vector is as follows: Divide the adjacent identical rotor states in the rotor state vector at the current acquisition time into the same group, determine the time interval of the acquisition times corresponding to all rotor states included 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 corresponding groups in the rotor state vector and the current state vector; Record the number of acquisition times with different values among the rotor states and the current state marking values with the same acquisition time in the corresponding groups in the rotor state vector and the current state vector as the number of different times in the corresponding groups of the rotor state vector and the current state vector; Record the ratio of the number of different times in the corresponding groups of the rotor state vector and the current state vector to the number of acquisition times included in the same group as the jitter coefficient of all acquisition times corresponding to the corresponding groups of the rotor state vector and the current state vector.

[0009] Furthermore, the method for determining the external force change amount at the acquisition time is as follows: Take the derivative of the input current vector at the current acquisition time with respect to time to obtain the input current derivative vector at the current acquisition time, and record the values included in the input current derivative vector at the current acquisition time as the external force change amounts at the acquisition times corresponding to the values.

[0010] Furthermore, the method for determining the jitter similarity weight at the acquisition moment is as follows: Denote any acquisition moment as the target acquisition moment, denote the absolute value of the difference between the target acquisition moment and the external force change amount at the current acquisition moment as the first absolute value of the target acquisition moment, and denote 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.

[0011] Furthermore, the method for determining the jitter evaluation value at the current acquisition moment is as follows: Take the jitter similarity weight of the acquisition moment as the weight of the jitter coefficient of the acquisition moment, perform weighted summation on the jitter coefficients of all acquisition moments, and denote the result of the weighted summation as the jitter evaluation value at the current acquisition moment.

[0012] Furthermore, combining the angular acceleration of the rotor and the jitter evaluation value at the current acquisition moment to achieve speed optimization control of the brushless DC motor includes the following specific methods: Denote the product of the angular acceleration of the rotor and the jitter evaluation value at the current acquisition moment as the rotor jitter cost at the current acquisition moment; When the jitter evaluation value at the current acquisition moment is greater than the first preset threshold, it is determined that the voltage of the brushless DC motor needs to be decreased; when the jitter evaluation value at the current acquisition moment is less than or equal to the first preset threshold, compare the rotor jitter cost at the current acquisition moment 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 decreased; denote the determination results of decreasing and increasing the voltage of the brushless DC motor as the voltage adjustment results of the brushless DC motor. If the rotor speed at the current acquisition moment is the same as the preset target speed, no speed adjustment is performed on the brushless DC motor; 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 decrease the voltage of the brushless DC motor, adjust the voltage of the brushless DC motor 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, adjust the voltage of the brushless DC motor 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, adjust the voltage of the brushless DC motor in the same way 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 no speed adjustment is performed on the brushless DC motor.

[0013] In a second aspect, an embodiment of the present invention further provides a rotational 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 the method described in any one of the above are implemented.

[0014] The beneficial effects of the present invention are as follows: This application takes into account that during the acceleration and deceleration processes of the rotor, the rotor state of the brushless DC motor does not exactly match 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 characteristics such as vibration and noise of the rotor. The degree of coincidence between the evaluated rotor state vector and the current state vector is evaluated to determine the jitter coefficient at all acquisition moments. The jitter coefficient is an evaluation result of the severity of the jitter situation of the rotor during the acceleration or deceleration process. Further, the similarity between the rotor state at each acquisition moment and the rotor state at the current acquisition moment is evaluated respectively to determine the jitter similarity weight at each acquisition moment. Based on the jitter similarity weights and jitter coefficients at all acquisition moments, the jitter evaluation value at the current acquisition moment is determined. During the process of obtaining the jitter evaluation value, it is determined according to the current acquisition moment and the jitter similarity weights and jitter coefficients within a 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 problem of inaccurate rotor state evaluation caused by rotor jitter caused by changes in the direct current dynamic force of the rotor. Finally, according to the jitter situation of the brushless DC motor, the voltage of the brushless DC motor is dynamically optimized to achieve rotational speed optimization control of the brushless DC motor, solve the problems of abnormal jitter and noise caused by improper rotational speed control of the brushless DC motor, reduce the jitter situation during the process of changing the rotational speed of the brushless DC motor, and effectively reduce the jitter wear and rotational noise of the rotor of the brushless DC motor. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or in the prior art, the following will briefly introduce the drawings required for use in the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on these drawings.

[0016] Figure 1 It is a flowchart showing the process of a rotational speed optimization control method for a brushless DC motor provided by an embodiment of the present invention; Figure 2 It is a flowchart for obtaining the jitter coefficient provided by an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0018] Please refer to Figure 1 , which shows a flowchart of a method for optimizing the speed control of a brushless DC motor provided by an embodiment of the present invention. The method includes the following steps: Step S001, collect the angular acceleration of the rotor, the attitude angle of the rotor, the input current of the brushless DC motor, and the three-phase current of the brushless DC motor within a preset time period before and at the current acquisition moment, mark the rotor state and the current state mark value of the rotor, and obtain the rotor state vector, the input current vector, and the current state vector at the current acquisition moment.

[0019] There is a three-phase inverter bridge circuit in the brushless DC motor. The three phases of the three-phase inverter bridge circuit respectively control three electromagnets in the motor. The circuit will automatically adjust the current period of each phase according to the rotation period of the rotor, so as to ensure that the electromagnet always does positive work on the rotor and endows the rotor with kinetic energy.

[0020] Use the Hall sensor built in the brushless DC motor to collect the angular acceleration of the rotor of the brushless DC motor.

[0021] Use the Hall sensor built in the brushless DC motor to collect the attitude angle of the rotor at each acquisition moment.

[0022] It can be understood that the value range of the attitude angle of the rotor is greater than or equal to 0° and less than 360°. The value of the attitude angle of the rotor represents the clockwise angle difference between the south pole of the rotor and the electromagnet corresponding to the 0° phase current. For example, when the attitude angle of the rotor is 0°, the south pole of the rotor points to the electromagnet corresponding to the 0° phase current.

[0023] According to the attitude angle of the rotor, mark the rotor state of the rotor. Uniformly divide the rotor states with attitude angles greater than or equal to 0° and less than 360° into 6 angular partitions, and mark each angular partition as 1 - 6 in ascending order. Specifically, the method for marking the rotor state of the rotor is as follows: Mark the rotor state with an attitude angle greater than or equal to 0° and less than 60° as 1, mark the rotor state with an attitude angle greater than or equal to 60° and less than 120° as 2, mark the rotor state with an attitude angle greater than or equal to 120° and less than 180° as 3, mark the rotor state with an attitude angle greater than or equal to 180° and less than 240° as 4, mark the rotor state with an attitude angle greater than or equal to 240° and less than 300° as 5, and mark the rotor state with an attitude angle greater than or equal to 300° and less than 360° as 6.

[0024] Use an ammeter to collect the input current of the brushless DC motor at each acquisition moment.

[0025] Use the Hall sensors built in the brushless DC motor to collect the three-phase current of the brushless DC motor. These three-phase currents are the 0° phase current, the 120° phase current, and the 240° phase current respectively. It can be understood that there are definite limiting relationships among the three-phase currents of the brushless DC motor. Specifically, at any moment, the current states of the three-phase currents include three types, where one phase current is positive, one phase current is negative, and the remaining one phase current is 0. This definite current state of the three-phase currents indicates that at any 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 the three-phase currents, which are: ① The 0° phase current is positive, the 120° phase current is negative, and the 240° phase current is 0; ② The 0° current is positive, the 240° phase current is negative, and the 120° phase current is 0; ③ The 120° current is positive, the 240° phase current is negative, and the 0° phase current is 0; ④ The 120° current is positive, the 0° phase current is negative, and the 240° phase current is 0; ⑤ The 240° current is positive, the 0° phase current is negative, and the 120° phase current is 0; ⑥ The 240° current is positive, the 120° phase current is negative, and the 0° phase current is 0.

[0026] Among them, the 6 current states of ① - ⑥ of the three-phase current correspond one-to-one with the 6 rotor states of 1 - 6 respectively. 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.

[0027] According to the values of the three-phase current of the brushless DC motor, mark the current state marking value of the three-phase current at the acquisition moment. Specifically, assign the current state marking values of the 6 current states of ① - ⑥ of the three-phase current as 1 - 6 in sequence.

[0028] Preferably, in an 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 megahertz, and the angular acceleration, attitude angle, input current, and three-phase current at the current collection moment and within 10 milliseconds before the current collection moment are collected. In the actual application process, as other implementation manners, the implementer can determine the sampling frequency and sampling time according to the actual situation by himself / herself, and the present application does not make special restrictions.

[0029] Arrange all rotor states in the order of the sequence of the collection moments corresponding to the rotor states, and obtain the rotor state vector at the current collection moment.

[0030] Arrange all input currents in the order of the sequence of the collection moments corresponding to the input currents, and obtain the input current vector at the current collection moment.

[0031] Arrange all current state flag values in the order of the sequence of the collection moments corresponding to the current state flag values, and obtain the current state vector at the current collection moment.

[0032] So far, the rotor state vector, input current vector, and current state vector at the current collection moment are obtained.

[0033] Step S002, according to the values of the rotor states in the rotor state vector at the current collection moment, and the value differences between the rotor states in the rotor state vector and the current state flag values at the same collection moment in the current state vector, determine the jitter coefficients at all collection moments respectively.

[0034] In the process of controlling the speed of a brushless DC motor, it is necessary to gradually increase or decrease the DC current input to the brushless DC motor. When the input current changes more slowly, the jitter wear during the acceleration or deceleration process of the motor is milder, and the generated noise is smaller. However, if the input current changes too slowly, the speed change of the motor will be too slow, affecting the acceleration performance of the motor. Therefore, it is necessary to dynamically adjust the change speed of the current to avoid problems such as large noise and serious wear caused by improper current control during the speed acceleration and deceleration process of the motor.

[0035] When the brushless DC motor operates stably, the rotor runs at a stable angular velocity in the same rotor state, and the rotor state of the brushless DC motor coincides with the current state corresponding to the input current. At this time, the direction of the magnetic moment of the electromagnet is the same as the direction of the linear velocity of the rotor, and the work efficiency of the current on the rotor is the highest. During the acceleration and deceleration processes of the rotor, since the speed of the rotor is constantly changing, the control system of the brushless DC motor cannot accurately predict the speed of the rotor, which will cause the rotor state of the brushless DC motor not to fully coincide with the current state corresponding to the input current, resulting in a difference between the direction of the magnetic moment of the electromagnet and the direction of the linear velocity of the rotor, and further leading to a decrease in the work efficiency of the current on the rotor. These reduced powers are released in the form of heat and friction, causing vibrations and noises in the rotor.

[0036] Therefore, during the acceleration or deceleration process of the rotor, the jitter situation of the rotor during the acceleration or deceleration process can be judged by the degree of coincidence between the rotor state vector and the current state vector.

[0037] According to the value of the rotor state in the rotor state vector at the current acquisition moment, the rotor state vector at the current acquisition moment is grouped.

[0038] 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 moments corresponding to all the rotor states included 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.

[0039] According to the value differences between the rotor state and the current state marker values at the same acquisition moment in the corresponding groups of the rotor state vector and the current state vector, the jitter coefficients at all acquisition moments are determined respectively.

[0040] The number of acquisition moments with different values in the rotor state and the current state marker values at the same acquisition moment in the corresponding groups of the rotor state vector and the current state vector is recorded as the number of different moments in the corresponding groups of the rotor state vector and the current state vector, and the ratio of the number of different moments in the corresponding groups of the rotor state vector and the current state vector to the number of acquisition moments included in the same group is recorded as the jitter coefficient of all the acquisition moments corresponding to the corresponding groups of the rotor state vector and the current state vector.

[0041] For ease of understanding, an example of obtaining the jitter coefficient is as follows. 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, the adjacent identical rotor states in the rotor state vector at the current acquisition moment are divided into the same group. Then, "1, 1, 1, 1" is the first group divided, "2, 2, 2, 2, 2" is the second group divided, and "3, 3, 3, 3" is the third group divided. A total of three groups are divided from the rotor state vector. According to the time intervals of the acquisition moments corresponding to all the rotor states included in the three groups divided from the rotor state vector, the rotor state vector should also be divided into three groups. Moreover, the first group includes the current state marker values corresponding to the first four acquisition moments, the second group includes the current state marker values corresponding to the fifth to ninth acquisition moments, and the first group includes the current state marker values corresponding to the last four acquisition moments. The three groups divided from the rotor state vector corresponding to "1, 1, 1, 1", "2, 2, 2, 2, 2", and "3, 3, 3, 3" are "6, 1, 1, 1", "1, 2, 2, 2, 3", and "3, 3, 3, 3" in sequence. For the corresponding groups in the first group of the rotor state vector and the current state vector, for the rotor state and the current state marker values with the same acquisition moment but different values in the corresponding groups of the rotor state vector and the current state vector, there is only the first moment. Then, the number of different moments in this group is 1, and the number of acquisition moments included in this group is 4. Therefore, the jitter coefficient corresponding to all the acquisition moments in this group is 0.25.

[0042] The flowchart for obtaining the jitter coefficient is as Figure 2 shown.

[0043] Thus, the jitter coefficients for all acquisition moments are obtained.

[0044] Step S003: According to the input current vector at the current acquisition moment, respectively determine the external force change amount for each acquisition moment. According to the differences between the external force change amounts at all acquisition moments and the external force change amount at the current acquisition moment, respectively determine the jitter similarity weights for each acquisition moment. According to the jitter similarity weights and jitter coefficients at all acquisition moments, determine the jitter evaluation value at the current acquisition moment.

[0045] When the rotor of a brushless DC motor rotates at a fixed angular velocity, the power provided by the direct current is equal to the resistance of the rotor rotation. At this time, the direct current remains unchanged, the rotor rotates stably and the amplitude of jitter is very small. When the direct current changes, the power provided by the direct current and the resistance of the rotor are no longer equal, and the rotor accelerates or decelerates. If the resultant force of the direct current power and the rotor resistance is not the force in the direction of the linear velocity, the rotor will jitter, and the greater the resultant force, the more severe the jitter. Therefore, the jitter of the rotor is related to the change amount of the power provided by the current.

[0046] According to the input current vector at the current acquisition moment, the change amount of the external force at each acquisition moment is determined respectively.

[0047] Derive the input current vector at the current acquisition moment with respect to time to obtain the input current derivative vector at the current acquisition moment, and record the values included in the input current derivative vector at the current acquisition moment as the change amount of the external force at the acquisition moment corresponding to the values.

[0048] According to the differences between the change amounts of the external forces at all acquisition moments and the change amount of the external force at the current acquisition moment, the jitter similarity weights at each acquisition moment are determined respectively.

[0049] Record any one acquisition moment as the target acquisition moment, record the absolute value of the difference between the change amount of the external force at the target acquisition moment and the change amount of the external force at the current acquisition moment as the first absolute value at the target acquisition moment, and record the normalized value of the reciprocal of the first absolute value at the target acquisition moment as the jitter similarity weight at the target acquisition moment.

[0050] Among them, in the process of calculating the reciprocal of the first absolute value at the target acquisition moment, the first absolute value at the target acquisition moment needs to be used as the denominator of the fraction. To avoid the situation of the denominator being zero, a preset value needs to be added to the denominator. The example value of the preset value is 0.01; the function of calculating the normalized value is to limit the sum of the jitter similarity weights at all acquisition moments to the constant 1.

[0051] When the difference between the change amount of the external force at the target acquisition moment and the change amount of the external force 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.

[0052] The jitter similarity weights at each acquisition moment can be obtained in the same way, that is, for any one acquisition moment, there is a corresponding jitter similarity weight.

[0053] According to the jitter similarity weights and the jitter coefficients at all acquisition moments, the jitter evaluation value at the current acquisition moment is determined.

[0054] Take the jitter similarity weight at the acquisition moment as the weight of the jitter coefficient at the acquisition moment, perform a weighted sum of the jitter coefficients at all acquisition moments, and record the result of the weighted sum as the jitter evaluation value at the current acquisition moment.

[0055] By weighting the jitter coefficient at the corresponding acquisition moment according to the current acquisition moment and the jitter similarity weight within 10 milliseconds before the current acquisition moment, the inaccuracy of the rotor state evaluation caused by measurement errors can be reduced. At the same time, it can avoid the problem that the rotor jitter caused by the change of the direct current dynamic force of the rotor leads to inaccurate rotor state evaluation.

[0056] Thus, the jitter evaluation value at the current acquisition moment is determined.

[0057] Step S004: Collect the rotor speed and voltage of the brushless DC motor at the current acquisition moment, and combine the angular acceleration and jitter evaluation value of the rotor at the current acquisition moment to achieve the speed optimization control of the brushless DC motor.

[0058] Determine the rotor jitter cost at the current acquisition moment according to the angular acceleration and jitter evaluation value of the rotor at the current acquisition moment.

[0059] Record the product of the angular acceleration and jitter evaluation value of the rotor at the current acquisition moment as the rotor jitter cost at the current acquisition moment.

[0060] The greater the angular acceleration and jitter evaluation value of the rotor 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 of the brushless DC motor to change the speed.

[0061] When the jitter evaluation value at the current acquisition moment is greater than the 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, compare the numerical relationship between the rotor jitter cost at the current acquisition moment and 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. Record the determination results of reducing and increasing the voltage of the brushless DC motor as the voltage adjustment result of the brushless DC motor.

[0062] Among them, both the first preset threshold and the second preset threshold are 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.

[0063] Use the Hall sensor built in the brushless DC motor to collect the rotor speed and voltage of the brushless DC motor at the current acquisition moment. If the rotor speed at the current acquisition moment is the same as the preset target speed, no speed adjustment is performed on the brushless DC motor. If the rotor speed at the current acquisition moment is different from the preset target speed of the rotor, adjust the voltage of the brushless DC motor according to the voltage adjustment result of the brushless DC motor. When the voltage adjustment result of the brushless DC motor is to decrease the voltage of the brushless DC motor, adjust the voltage of the brushless DC motor 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, adjust the voltage of the brushless DC motor to 1.1 times the voltage of the brushless DC motor at the current acquisition moment.

[0064] At the next acquisition moment after the current acquisition moment, adjust the voltage of the brushless DC motor in the same way 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 no speed adjustment is performed on the brushless DC motor.

[0065] Among them, the preset target speed of the rotor is a value preset manually before the use of the brushless DC motor, and is set by those skilled in the art according to the use requirements of the brushless DC motor.

[0066] When the voltage of the brushless DC motor changes, the rotor speed of the brushless DC motor will also change. Thus, according to the jitter situation of the brushless DC motor, dynamically optimize the voltage of the brushless DC motor, complete the speed optimization control, reduce the jitter situation in the process of changing the speed of the brushless DC motor, and effectively reduce the jitter wear and rotational noise of the rotor of the brushless DC motor.

[0067] Thus, the speed optimization control of the brushless DC motor is realized.

[0068] 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 methods for the speed optimization control method of a brushless DC motor are realized.

[0069] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for optimizing the rotational speed control of a brushless DC motor, characterized in that, The method includes the following steps: Collect the angular acceleration of the rotor, the attitude angle of the rotor, the input current of the brushless DC motor, and the three-phase current of the brushless DC motor within a preset time period before and at the current acquisition moment, mark the rotor state of the rotor and the current state marking value, and obtain the rotor state vector, the input current vector, and the current state vector at the current acquisition moment; 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 marking value at the same acquisition moment in the current state vector, determine the jitter coefficients at all acquisition moments respectively; According to the input current vector at the current acquisition moment, determine the external force change amount at each acquisition moment respectively. According to the difference between the external force change amounts at all acquisition moments and the external force change amount at the current acquisition moment, determine the jitter similarity weights at each acquisition moment respectively. According to the jitter similarity weights and jitter coefficients at all acquisition moments, determine the jitter evaluation value at the current acquisition moment; Collect the rotor speed and voltage of the brushless DC motor at the current acquisition moment, and combine the angular acceleration of the rotor and the jitter evaluation value at the current acquisition moment to achieve the speed optimization control of the brushless DC motor.

2. The rotational speed optimization control method of a brushless DC motor according to claim 1, characterized in that, The specific methods included in the marking of the rotor state of the rotor and the obtaining of the rotor state vector at the current acquisition moment are as follows: Evenly divide the rotor states with attitude angles greater than or equal to 0° and less than 360° into 6 angular partitions, and mark the angular partitions 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.

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

4. A speed optimization control method for a brushless DC motor according to claim 2, characterized in that The marking method of the current state marking value and the obtaining method of the current state vector respectively include: Determine 6 current states of the three-phase current corresponding one by one to the angular partitions marked as 1-6, and assign the current state marking values of the 6 current states as 1-6 in sequence; Arrange all current state marking values in the order of the acquisition moments corresponding to the current state marking values, and obtain the current state vector at the current acquisition moment.

5. A speed optimization control method for a brushless DC motor according to claim 2, characterized in that The specific method obtained by determining the jitter coefficients at 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 marking value at the same acquisition moment in the current state vector is as follows: Divide the 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 included 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 corresponding groups in the rotor state vector and the current state vector; The number of acquisition times with different values among the rotor state and current state marker values corresponding to the same acquisition time within the group in the rotor state vector and the current state vector is denoted as the number of different times of the corresponding group in the rotor state vector and the current state vector; the ratio of the number of different times of the corresponding group in the rotor state vector and the current state vector to the number of acquisition times included in the same group is denoted as the jitter coefficient of all acquisition times corresponding to the corresponding group in the rotor state vector and the current state vector.

6. A speed optimization control method for a brushless DC motor according to claim 1, characterized in that, The method for determining the external force change amount at the acquisition time is as follows: Derive the input current vector at the current acquisition time with respect to time to obtain the input current derivative vector at the current acquisition time, and denote the value included in the input current derivative vector at the current acquisition time as the external force change amount at the acquisition time corresponding to the value.

7. A speed optimization control method for a brushless DC motor according to claim 1, characterized in that, The method for determining the jitter similarity weight at the acquisition time is as follows: Denote any acquisition time as the target acquisition time, denote the absolute value of the difference between the external force change amount at the target acquisition time and the external force change amount at the current acquisition time as the first absolute value of the target acquisition time, and denote the normalized value of the reciprocal of the first absolute value of the target acquisition time as the jitter similarity weight at the target acquisition time.

8. A speed optimization control method for a brushless DC motor according to claim 1, characterized in that The method for determining the jitter evaluation value at the current acquisition time is as follows: Take the jitter similarity weight at the acquisition time as the weight of the jitter coefficient at the acquisition time, perform weighted summation on the jitter coefficients at all acquisition times, and denote the result of the weighted summation as the jitter evaluation value at the current acquisition time.

9. A speed optimization control method for a brushless DC motor according to claim 1, characterized in that The method for realizing the speed optimization control of the brushless DC motor by combining the angular acceleration and the jitter evaluation value of the rotor at the current acquisition time includes the following specific methods: Denote the product of the angular acceleration of the rotor at the current acquisition time and the jitter evaluation value as the rotor jitter cost at the current acquisition time; When the jitter evaluation value at the current acquisition time is greater than the 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 time is less than or equal to the first preset threshold, compare the rotor jitter cost at the current acquisition time with the second preset threshold. If the rotor jitter cost at the current acquisition time 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 time 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; denote the determination results of reducing and increasing the voltage of the brushless DC motor as the voltage adjustment results of the brushless DC motor; If the rotor speed at the current acquisition time 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 time 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, adjust the voltage of the brushless DC motor to 0.9 times the voltage of the brushless DC motor at the current acquisition time. When the voltage adjustment result of the brushless DC motor is to increase the voltage of the brushless DC motor, adjust the voltage of the brushless DC motor to 1.1 times the voltage of the brushless DC motor at the current acquisition time; At the next acquisition moment after the current acquisition moment, the voltage of the brushless DC motor is adjusted in the same way 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.

10. 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 method according to any one of claims 1-9 are implemented.

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