CN117578923A - Method for reducing resonance of stepping motor system - Google Patents

Method for reducing resonance of stepping motor system Download PDF

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Publication number
CN117578923A
CN117578923A CN202311548400.1A CN202311548400A CN117578923A CN 117578923 A CN117578923 A CN 117578923A CN 202311548400 A CN202311548400 A CN 202311548400A CN 117578923 A CN117578923 A CN 117578923A
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CN
China
Prior art keywords
frequency
stepping motor
pwm
multiplication
stepper motor
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Pending
Application number
CN202311548400.1A
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Chinese (zh)
Inventor
王威
韩晓新
钱剑东
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Jiangsu University of Technology
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Jiangsu University of Technology
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Application filed by Jiangsu University of Technology filed Critical Jiangsu University of Technology
Priority to CN202311548400.1A priority Critical patent/CN117578923A/en
Publication of CN117578923A publication Critical patent/CN117578923A/en
Pending legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P8/00—Arrangements for controlling dynamo-electric motors of the kind having motors rotating step by step
    • H02P8/12—Control or stabilisation of current
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02P—CONTROL OR REGULATION OF ELECTRIC MOTORS, ELECTRIC GENERATORS OR DYNAMO-ELECTRIC CONVERTERS; CONTROLLING TRANSFORMERS, REACTORS OR CHOKE COILS
    • H02P8/00—Arrangements for controlling dynamo-electric motors of the kind having motors rotating step by step
    • H02P8/32—Reducing overshoot or oscillation, e.g. damping

Abstract

The invention belongs to the technical field of stepping motor control, and particularly relates to a method for reducing the resonance of a stepping motor system. The method comprises the following steps: step S1, determining the inherent frequency and the frequency multiplication thereof, the torque pulse frequency and the frequency multiplication thereof, and the PWM frequency and the frequency multiplication thereof of a stepping motor system; step S2, PWM subdivision at the zero crossing point of the rotor current of the stepping motor is reduced; and S3, adjusting the natural frequency and the frequency multiplication thereof of the stepping motor system, the torque pulse frequency and the frequency multiplication thereof, and the PWM frequency and the frequency multiplication thereof. The invention solves the problems of torque disappearance and vibration and resonance caused by the fact that the current at the current zero crossing point is continuously zero by reducing PWM subdivision at the current zero crossing point of the rotor of the stepping motor. The invention adjusts the torque pulse frequency and the PWM frequency, so that the torque pulse frequency and the PWM frequency keep a safe interval with the natural frequency of the stepping motor system, and simultaneously keep three-frequency separation, thereby reducing the risk of resonance of the system in a low frequency band and a high frequency band.

Description

Method for reducing resonance of stepping motor system
Technical Field
The invention belongs to the technical field of stepping motor control, and particularly relates to a method for reducing the resonance of a stepping motor system.
Background
The stepping motor system can provide accurate rotation speed and rotation angle control and various levels of torque, and is widely applied to various fields such as measurement and control, engineering machinery, numerical control equipment, robot energy and the like. The presence of natural frequencies of the stepper motor system, electromagnetic torque pulses, PWM high frequency pulses, etc., especially when these frequencies overlap, will result in non-negligible resonances of the stepper motor system.
The natural frequency of the stepping motor system is generally in a low frequency band, and two methods for solving the vibration and resonance problems of the stepping motor system are generally adopted in the prior art: in the first method, by increasing the subdivision of the PWM pulse output from the stepper motor controller, the current variation input into the stepper motor rotor is slowed down, i.e. by reducing the amount of variation per unit time of the stepper motor input current, the torque abrupt amount caused by the current variation is reduced, and thus the vibration and resonance of the stepper motor system are reduced. Increasing the subdivision also has another benefit that the PWM control frequency and the input current frequency of the stepping motor are increased by increasing the subdivision, so that the natural frequency interval of the stepping motor in a low frequency band can be effectively avoided, and the generation of resonance is effectively avoided. However, high-frequency PWM also brings about certain side effects, namely, the system has abundant high-frequency components and high-frequency harmonic components, and brings about the influence and interference of high-frequency noise to the stepper motor system. Another approach to addressing vibration and resonance in stepper motor systems is to increase shock damping, increase torque load, and increase the speed reduction mechanism. The vibration damping is a physical vibration damping method, such as adding a rubber gasket in the system, implementing rigid connection between the output rotating shaft and the load, and the like, and transmitting the vibration of the stepping motor system to the outside of the system in a physical manner, so as to reduce the vibration and resonance of the system, thus being a measure that cannot reduce or eliminate the vibration and resonance of the system at all. In addition, the principle of increasing the torque load is consistent with that of increasing the speed reducing mechanism, and the rotating speed of the stepping motor is increased by increasing the output torque, so that the range of the natural frequency interval of the stepping motor system is avoided, and the possibility of vibration and resonance is reduced. In addition, the stepping motor has a current pulse at the time of phase switching, and a period in which the current has zero at the zero crossing point, which causes a problem of torque extinction and the like, and also causes a torque pulse, which in turn causes vibration and resonance of the stepping motor system.
In order to reduce vibration and resonance of the stepping motor system, PWM subdivision at zero crossing points of the stepping motor rotor current is reduced, a time zone of zero current is eliminated, and further vibration of the stepping motor caused by torque disappearance due to zero current is eliminated. The system resonance is reduced by adjusting the natural frequency, the torque pulse frequency and the PWM frequency interval.
Disclosure of Invention
The invention provides a method for reducing the resonance of a stepping motor system, which solves the problem that the conventional method cannot comprehensively consider the separation of the natural frequency, the torque pulse frequency and the PWM frequency of the stepping motor system, and reduces the possibility of the resonance of the system in a low frequency band and a high frequency band. The invention solves the problems of torque disappearance and vibration and resonance caused by the fact that the current at the current zero crossing point is continuously zero by reducing PWM subdivision at the current zero crossing point of the rotor of the stepping motor.
In order to achieve the above purpose, the present invention provides the following technical solutions:
a method of reducing resonance in a stepper motor system, comprising the steps of:
step S1, determining the inherent frequency and the frequency multiplication thereof, the torque pulse frequency and the frequency multiplication thereof, and the PWM frequency and the frequency multiplication thereof of a stepping motor system;
step S2, PWM subdivision at the zero crossing point of the rotor current of the stepping motor is reduced;
and S3, adjusting the natural frequency and the frequency multiplication thereof of the stepping motor system, the torque pulse frequency and the frequency multiplication thereof, and the PWM frequency and the frequency multiplication thereof.
The technical scheme is further optimized, and the step S1 comprises the following steps:
a) Natural frequency and frequency multiplication of the stepping motor system:
wherein f g_1 For the natural frequency of the stepping motor, f g_i I=2, 3..is a frequency multiplication of the natural frequency of the stepper motor, T is the holding torque of the stepper motor, Z is the number of teeth of the rotor of the stepper motor, J is the rotational inertia of the rotor of the stepper motor;
b) Torque pulse frequency and frequency multiplication thereof:
wherein f z_1 For torque pulse frequency, f z_i I=2, 3..is the multiplication of the torque pulse frequency, Z is the number of rotor teeth of the stepper motor, n is the stepper motor speed;
c) PWM frequency and its frequency multiplication:
f p_i ＝i·f p_1 , i＝1,2,... (3)
wherein f p_1 For the PWM frequency sent by the stepper motor controller.
The technical scheme is further optimized, and the step S2 comprises the following steps:
let the current number of subdivisions of the stepper motor be m, then the subdivision of PWM at zero crossing is m zero The method comprises the following steps:
according to still further optimization of the technical scheme, the step S3 comprises the following steps:
taking the ith harmonic frequency and taking the minimum value f of the absolute value of the frequency difference ζ_i Is that
f ζ_i ＝min{|f g_i -f z_i |,|f g_i -f p_i |,|f z_i -f p_i |}, i＝1,2,... (5)
From the formulae (1), (2) and (3), f ζ_i The minimum value of i=1, 2,..;
f ζ_1 ＝k*f g_1 (6)
wherein k is [1.2,2.2].
Compared with the prior art, the technical scheme has the following beneficial effects:
1. the problem that the natural frequency, the torque pulse frequency and the PWM frequency of the stepping motor system are separated cannot be comprehensively considered in the traditional method, and the possibility of resonance of the system in a low frequency band and a high frequency band is reduced.
2. By reducing PWM subdivision at the zero crossing point of the rotor current of the stepping motor, the problems of torque disappearance and vibration and resonance caused by torque disappearance due to continuous zero current at the zero crossing point of the current are solved.
Drawings
Fig. 1 is a flow chart of frequency adjustment.
Detailed Description
In order to describe the technical content, constructional features, achieved objects and effects of the technical solution in detail, the following description is made in connection with the specific embodiments in conjunction with the accompanying drawings.
Referring to fig. 1, a control flow chart for reducing the resonance of a stepping motor is shown. The method for reducing the resonance of the stepping motor system according to the preferred embodiment of the invention comprises the following specific steps:
1. the inherent frequency and the frequency multiplication thereof, the torque pulse frequency and the frequency multiplication thereof, and the PWM frequency and the frequency multiplication thereof of the stepping motor system are determined.
a) Natural frequency and frequency multiplication of the stepping motor system:
wherein f g_1 For the natural frequency of the stepping motor, f g_i I=2, 3..is a multiple of the natural frequency of the stepper motor, T is the holding torque of the stepper motor, Z is the number of teeth of the rotor of the stepper motor, and J is the rotational inertia of the rotor of the stepper motor.
b) Torque pulse frequency and frequency multiplication thereof:
wherein f z_1 For torque pulse frequency, f z_i I=2, 3..is a multiple of the torque pulse frequency, Z is the number of rotor teeth of the stepper motor, and n is the stepper motor speed.
c) PWM frequency and its frequency multiplication:
f p_i ＝i·f p_1 , i＝1,2,... (3)
wherein f p_1 For the PWM frequency sent by the stepper motor controller.
In order to prevent the step motor system from resonating, the natural frequency and frequency multiplication thereof, the torque pulse frequency and frequency multiplication thereof, the PWM frequency and frequency multiplication thereof must not overlap in frequency spectrum, especially the natural frequency f of the step motor in the low frequency band g_1 Overlap, which is a major factor in reducing system resonance.
2. In order to solve the problems of torque disappearance and vibration and resonance caused by the fact that the current at the current zero crossing point is continuously zero, PWM subdivision at the current zero crossing point of the rotor of the stepping motor is reduced:
let the current number of subdivisions of the stepper motor be m, then the subdivision of PWM at zero crossing is m zero The method comprises the following steps:
it can be seen from the above that the subdivision m at the zero crossing point is no matter what the PWM subdivision value is zero All satisfy m zero And less than or equal to 8, so that subdivision at zero crossing points is small enough to ensure the transformation speed of zero crossing point current, further reduce and eliminate the time period when the current is zero, and further reduce vibration caused by torque (force) disappearance caused by current disappearance.
3. The natural frequency and the frequency multiplication thereof, the torque pulse frequency and the frequency multiplication thereof, and the frequency spectrum interval between the PWM frequency and the frequency multiplication thereof are adjusted, so that the risk of resonance is reduced. Taking the ith harmonic frequency and taking the minimum value f of the absolute value of the frequency difference ζ_i Is that
f ζ_i ＝min{|f g_i -f z_i |,|f g_i -f p_i |,|f z_i -f p_i |}, i＝1,2,... (5)
From the formulae (1), (2) and (3), f ζ_i The minimum value of i=1, 2,..a minimum value is found where i=1, i.e. the natural frequency attachment of the stepper motor system in the low frequency region. This means that in the low frequency regionThe natural frequency, torque pulse frequency and PWM frequency of the stepping motor system are easy to cause frequency aliasing, and the area is the area where resonance is most easy to occur, so that important consideration is needed to control f ζ_1 To ensure that no frequency aliasing occurs. For engineering application, the range of the working frequency which deviates from the range of 1.2 times to 2.2 times of the natural frequency is required to be good in general experience, resonance is easy to occur due to the fact that the gap is too small, the control of PWM frequency and torque pulse frequency is not facilitated, and even high-frequency-multiplication aliasing is caused, and the intermediate value is:
f ζ_1 ＝1.2*f g_1 (6)
the maximum continuous working frequency is also considered for frequency adjustment, and the maximum continuous working frequency is taken as the upper limit of frequency adjustment, so that the stepping motor system can not be out of step and spread during working, and a specific frequency adjustment flow chart is shown in fig. 1.
Referring to fig. 1, a frequency adjustment flow chart is shown, and the load torque, the subdivision number at the zero crossing position of the current, the maximum continuous running frequency and the inherent frequency of the stepper motor are first determined; then solve f ζ_1 Judgment f ζ_1 ≥1.2*f g_1 : if yes, controlling the motor rotation speed change to solve f again ζ_1 Otherwise, increasing PWM frequency to solve f again ζ_1 。
The invention solves the problems of torque disappearance and vibration and resonance caused by the fact that the current at the current zero crossing point is continuously zero by reducing PWM subdivision at the current zero crossing point of the rotor of the stepping motor. The invention adjusts the torque pulse frequency and the PWM frequency, so that the torque pulse frequency and the PWM frequency keep a safe interval with the natural frequency of the stepping motor system, and simultaneously keep three-frequency separation, thereby reducing the risk of resonance of the system in a low frequency band and a high frequency band. The PWM frequency adjustment does not take 1.2 times as a unique value in the formula (6), and the range of 1.2-2.2 can meet the requirement of reducing frequency aliasing.
The innovation point of the invention is that:
1. the natural frequency, the torque pulse frequency and the PWM frequency of the stepping motor system are determined, so that a frequency spectrum basis is provided for reducing and eliminating system vibration and resonance.
2. By reducing PWM subdivision at the zero crossing point of the rotor current of the stepping motor, the problems of torque disappearance and vibration and resonance caused by torque disappearance due to continuous zero current at the zero crossing point of the current are solved.
3. The torque pulse frequency and the PWM frequency are adjusted, so that a safe interval is kept between the torque pulse frequency and the natural frequency of the stepping motor system, and three-frequency separation is kept, and the risk of resonance of the system in a low frequency band and a high frequency band is reduced.
It is noted that relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Moreover, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or terminal that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or terminal. Without further limitation, an element defined by the statement "comprising … …" or "comprising … …" does not exclude the presence of additional elements in a process, method, article or terminal device comprising the element. Further, herein, "greater than," "less than," "exceeding," and the like are understood to not include the present number; "above", "below", "within" and the like are understood to include this number.
While the embodiments have been described above, other variations and modifications will occur to those skilled in the art once the basic inventive concepts are known, and it is therefore intended that the foregoing description and drawings illustrate only embodiments of the invention and not limit the scope of the invention, and it is therefore intended that the invention not be limited to the specific embodiments described, but that the invention may be practiced with their equivalent structures or with their equivalent processes or with their use directly or indirectly in other related fields.

Claims (4)

1. A method of reducing resonance in a stepper motor system, comprising the steps of:
step S1, determining the inherent frequency and the frequency multiplication thereof, the torque pulse frequency and the frequency multiplication thereof, and the PWM frequency and the frequency multiplication thereof of a stepping motor system;
step S2, PWM subdivision at the zero crossing point of the rotor current of the stepping motor is reduced;
and S3, adjusting the natural frequency and the frequency multiplication thereof of the stepping motor system, the torque pulse frequency and the frequency multiplication thereof, and the PWM frequency and the frequency multiplication thereof.
2. The method for reducing resonance of a stepper motor system as set forth in claim 1, wherein said step S1 includes:
a) Natural frequency and frequency multiplication of the stepping motor system:
wherein f g_1 For the natural frequency of the stepping motor, f g_i I=2, 3..is a frequency multiplication of the natural frequency of the stepper motor, T is the holding torque of the stepper motor, Z is the number of teeth of the rotor of the stepper motor, J is the rotational inertia of the rotor of the stepper motor;
b) Torque pulse frequency and frequency multiplication thereof:
wherein f z_1 For torque pulse frequency, f z_i I=2, 3..is the multiplication of the torque pulse frequency, Z is the number of rotor teeth of the stepper motor, n is the stepper motor speed;
c) PWM frequency and its frequency multiplication:
f p_i ＝i·f p_1 ,i＝1,2,...(3)
wherein f p_1 For the PWM frequency sent by the stepper motor controller.
3. The method of reducing resonance of a stepper motor system as set forth in claim 1, wherein said step S2 includes:
let the current number of subdivisions of the stepper motor be m, then the subdivision of PWM at zero crossing is m zero The method comprises the following steps:
4. the method for reducing resonance of a stepper motor system as set forth in claim 2, wherein said step S3 includes:
taking the ith harmonic frequency and taking the minimum value f of the absolute value of the frequency difference ζ_i Is that
f ζ_i ＝min{|f g_i -f z_i |,|f g_i -f p_i |,|f z_i -f p_i |},i＝1,2,... (5)
From the formulae (1), (2) and (3), f ζ_i The minimum value of i=1, 2,..;
f ζ_1 ＝k*f g_1 (6)
wherein k is [1.2,2.2].
CN202311548400.1A 2023-11-17 2023-11-17 Method for reducing resonance of stepping motor system Pending CN117578923A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
CN202311548400.1A CN117578923A (en) 2023-11-17 2023-11-17 Method for reducing resonance of stepping motor system

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
CN202311548400.1A CN117578923A (en) 2023-11-17 2023-11-17 Method for reducing resonance of stepping motor system

Publications (1)

Publication Number Publication Date
CN117578923A true CN117578923A (en) 2024-02-20

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ID=89889393

Family Applications (1)

Application Number Title Priority Date Filing Date
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Country Status (1)

Country Link
CN (1) CN117578923A (en)

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