Random modulation method and system for permanent magnet motor servo driving system

Abstract

The invention discloses a random modulation method and system for a permanent magnet motor servo driving system, and belongs to the technical field of motor control, and the random modulation method for the permanent magnet motor servo driving system comprises the steps: obtaining the real-time rotating speed of a permanent magnet motor, and setting the parameters of the permanent magnet motor; determining a carrier wave ratio based on the real-time rotating speed of the permanent magnet motor, and obtaining a carrier wave ratio influence factor; constructing an extended frequency envelope function by using the carrier ratio impact factor; determining a random spread spectrum period according to the spread frequency envelope function; and realizing modulation based on the random spread spectrum period. According to the random modulation method for the permanent magnet motor servo driving system, the influence of the carrier wave ratio and the spread spectrum range on the motor control performance is comprehensively considered, the harmonic dispersion effect brought by spread spectrum modulation is fully exerted, and the adverse influence of traditional random modulation on the motor control performance under the low carrier wave ratio working condition is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and in particular to a random modulation method and system for a permanent magnet motor servo drive system. Background Art

[0002] With the rapid development of industrial automation and intelligent manufacturing technology, permanent magnet synchronous motor (PMSM) servo drive systems have been widely used in modern industry due to their high efficiency, high power density and excellent dynamic performance. However, in the traditional space vector pulse width modulation strategy, the high-frequency action of the switching device will produce serious electromagnetic interference, which will affect the stability of the system and interfere with the peripheral equipment, making it difficult to meet the electromagnetic compatibility requirements. Although the traditional spread spectrum random modulation strategy can suppress electromagnetic interference, the large-scale spread spectrum will lead to increased torque pulsation and current distortion, affecting the smoothness and control accuracy of the motor. In addition, as the motor speed increases, the use of a fixed spread spectrum range under low carrier ratio conditions will further deteriorate the control performance of the motor, resulting in poor dynamic response, reduced efficiency, and even possible system oscillation. Summary of the invention

[0003] The purpose of the present application is to overcome the defects of the prior art and provide a random modulation method and system for a permanent magnet motor servo drive system, which can comprehensively consider the carrier ratio and the spread spectrum range.

[0004] In a first aspect, the present application provides a random modulation method for a permanent magnet motor servo drive system, comprising the following steps: Get the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor; Determine the carrier ratio based on the real-time speed of the permanent magnet motor, and obtain a carrier ratio influencing factor; constructing an extended frequency envelope function using the carrier ratio influence factor; Determining a random spread spectrum period according to the spread frequency envelope function; Modulation is achieved based on the random spreading period.

[0005] Optionally, the carrier ratio N The expression is as follows: in, f T is the electrical frequency of the permanent magnet motor; f Z is the pulse width modulation carrier frequency.

[0006] Optionally, the electrical frequency of the permanent magnet motor f T The expression is as follows: in, n is the real-time speed of the permanent magnet motor, p is the number of pole pairs of the permanent magnet motor.

[0007] Optionally, the carrier ratio influence factor e n The expression is as follows: in, N min is the minimum carrier ratio.

[0008] Optionally, the expression of the extended frequency envelope function is as follows: , in, is the carrier ratio influence factor e n The maximum value of the down-spread spectrum carrier frequency, is the carrier ratio influence factor e n The minimum value of the down-spread spectrum carrier frequency, is the minimum spread spectrum range, is the maximum spread spectrum range, f Z is the PWM carrier frequency.

[0009] Optionally, the expression of the random spreading period is as follows: in, For the k The random spread spectrum period of the switch, For the k A switching frequency.

[0010] Optionally, the k Switching frequency The expression is as follows: in, R is a random number, is the carrier ratio influence factor e n The maximum value of the down-spread spectrum carrier frequency, is the carrier ratio influence factor e n Minimum value of down-spread spectrum carrier frequency.

[0011] Optionally, a random number R The range of variation includes [0, 1].

[0012] Optionally, the modulation includes: space vector pulse width modulation.

[0013] In a second aspect, the present application further provides a random modulation system for a permanent magnet motor servo drive system, applying the random modulation method for a permanent magnet motor servo drive system as described in any one of the first aspects, including: Data acquisition module, used to obtain the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor; A random carrier frequency generation module is used to obtain a carrier ratio, a carrier ratio influence factor, and an extended frequency envelope function based on the real-time speed of the permanent magnet motor and the permanent magnet motor parameters, and determine a random spread spectrum period; A modulation module is used to perform modulation according to the random spread spectrum period.

[0014] The present application provides a random modulation method and system for a permanent magnet motor servo drive system, which establishes a connection between the random modulation spread spectrum range and the speed of the permanent magnet motor servo system through the carrier ratio and the carrier ratio influencing factor; by constructing an extended frequency envelope function, the spread spectrum range can be dynamically adjusted, and by dynamically adjusting the spread spectrum range under different carrier ratios, the spectrum energy can be more effectively dispersed, taking into account both the suppression of electromagnetic interference and the optimization of motor control performance; the spread spectrum range can be dynamically adjusted to adapt to the control requirements under different speeds and carrier ratios; while suppressing electromagnetic interference, torque pulsation and current distortion can be minimized, thereby comprehensively improving the performance and reliability of the permanent magnet motor servo drive system; it can not only meet the high-precision and high-efficiency control requirements, but also provide technical support for permanent magnet motors in a wider range of application scenarios, and promote the development of industrial automation and intelligence.

[0015] In order to make the above features and advantages of the invention more obvious and easy to understand, embodiments are given below and described in detail with reference to the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the related technologies, the drawings required for use in the embodiments or the related technical descriptions are briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0017] Figure 1 This is a flow chart of a random modulation method for a permanent magnet motor servo drive system provided in one embodiment of the present application.

[0018] Figure 2 This is a diagram of an extended frequency envelope function in a random modulation method for a permanent magnet motor servo drive system provided in one embodiment of the present application.

[0019] Figure 3A random switching cycle distribution diagram in a random modulation method for a permanent magnet motor servo drive system provided in another embodiment of the present application.

[0020] Figure 4 A schematic structural diagram of a random modulation system for a permanent magnet motor servo drive system provided in another embodiment of the present application. DETAILED DESCRIPTION

[0021] In order to make the purpose and technical solution of the embodiment of the present application clearer, the technical solution of the embodiment of the present application will be clearly and completely described in conjunction with the drawings of the embodiment of the present application. Obviously, the described embodiment is a part of the embodiment of the present application, not all of the embodiments. Based on the described embodiment of the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0022] In one embodiment, see Figure 1 The present application provides a random modulation method for a permanent magnet motor servo drive system. The random modulation method for a permanent magnet motor servo drive system may include the following steps: step S1 to step S5.

[0023] Step S1: Obtain the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor.

[0024] Step S2: determining the carrier ratio based on the real-time rotation speed of the permanent magnet motor, and obtaining a carrier ratio influencing factor.

[0025] Step S3: constructing an extended frequency envelope function using the carrier ratio influence factor.

[0026] Step S4: Determine the random spread spectrum period according to the spread frequency envelope function.

[0027] Step S5: Modulating based on the random spread spectrum period to generate a drive signal to drive the permanent magnet motor.

[0028] In the random modulation method for the permanent magnet motor servo drive system of the present application, by obtaining the real-time speed of the permanent magnet motor and setting parameters, the motor operation state can be accurately grasped; based on the real-time speed of the permanent magnet motor, the carrier ratio and the carrier ratio influencing factor are determined, and the connection between the random modulation spread spectrum range and the speed of the permanent magnet motor servo system can be established. By dynamically adjusting the spread spectrum range under different carrier ratios, the spectrum energy can be more effectively dispersed, taking into account the suppression of electromagnetic interference and the optimization of motor control performance. The method of the present application can also reduce torque pulsation and current distortion, optimize motor control performance, improve the stability and reliability of system operation, and provide strong support for the efficient application of permanent magnet motors in multiple fields.

[0029] In step S1, see Figure 1 In step S1, the real-time speed of the permanent magnet motor is obtained and the parameters of the permanent magnet motor are set.

[0030] As an example, the real-time speed of the permanent magnet motor can be obtained by using sensors or without sensors. The sensors may include speed sensors such as Hall sensors, photoelectric encoders, and rotary transformers. Specifically, the Hall sensor obtains the real-time speed of the permanent magnet motor by monitoring the change of the magnetic field; the photoelectric sensor uses the principle of photoelectric conversion to convert the angular displacement of the permanent magnet motor into an electrical pulse signal to obtain the speed. These speed sensors can convert the mechanical rotational motion of the permanent magnet motor into electrical signals, provide accurate data for subsequent control algorithms, and enable the control system to adjust the control strategy in time according to the actual state of the motor, thereby improving the control accuracy of the motor.

[0031] Furthermore, the permanent magnet motor parameters can be set by means of permanent magnet motor nameplate, reference manual, experimental measurement, empirical value, etc., and the permanent magnet motor parameters can include basic parameters such as maximum speed, pole pair number, rated voltage, rated current, rated power, stator resistance, stator inductance, flux linkage, moment of inertia, rated speed, etc. The motor electrical frequency is further calculated based on the maximum speed and pole pair number.

[0032] In step S2, see Figure 1 In step S2, the carrier ratio is determined based on the real-time speed of the permanent magnet motor to obtain a carrier ratio influencing factor.

[0033] As an example, the electrical frequency of the permanent magnet motor is obtained based on the real-time speed of the permanent magnet motor. f T , the following formula can be used: in, f T is the electrical frequency of the permanent magnet motor, which is the same as the modulation wave frequency and is in Hz; n The real-time speed of the permanent magnet motor is obtained in r / min. p is the number of pole pairs of the permanent magnet motor.

[0034] Furthermore, the carrier ratio N for: in, f T is the electrical frequency of the permanent magnet motor, which is the same as the modulation wave frequency and is in Hz; f Z is the PWM carrier frequency in Hz.

[0035] Furthermore, according to the electrical frequency of the permanent magnet motor fT Formula and carrier ratio N From the formula, we know that when the real-time speed of the permanent magnet motor is n When it is at its maximum value, there is a minimum carrier ratio N min , we can get the carrier ratio influence factor e n for: in, e n is the carrier ratio influence factor, and its value range is (0, 1]; N min is the minimum carrier ratio.

[0036] In step S3, see Figure 1 In step S3, the extended frequency envelope function is constructed using the carrier ratio influence factor.

[0037] As an example, the expression of the extended frequency envelope function is as follows: , in, is the current carrier ratio impact factor e n The maximum value of the down-spread spectrum carrier frequency, is the current carrier ratio impact factor e n The minimum value of the down-spread spectrum carrier frequency, is the minimum spread spectrum range, is the maximum spread spectrum range, f Z is the PWM carrier frequency.

[0038] As an example, the maximum spread spectrum range The value can be 40%, the minimum spread spectrum range The value can be 10%.

[0039] In an example, see Figure 2 , Figure 2 is the extended frequency envelope function constructed under a certain spread spectrum range, where the horizontal axis represents the carrier ratio influence factor; the vertical axis represents the carrier frequency, that is, the frequency of the carrier involved in the modulation process in the permanent magnet motor servo drive system; the upper curve is the upper limit of the extended frequency envelope function, that is, the current carrier ratio influence factor The maximum value that the spread spectrum carrier frequency can reach; the curve below is the lower limit of the extended frequency envelope function, that is, under the current carrier ratio influence factor , the minimum value that the spread spectrum carrier frequency can reach. The middle line represents the value of the spread spectrum carrier frequency between the upper and lower limits under different carrier ratio influence factors. Figure 2 It can be seen that with the change of the carrier ratio influence factor, the spread spectrum carrier frequency fluctuates within the upper and lower limits, reflecting the constraint and modulation effect of the spread frequency envelope function on the spread spectrum carrier frequency, and showing the dynamic range and trend of the spread spectrum carrier frequency changing with the carrier ratio influence factor within the spread spectrum range.

[0040] In step S4, see Figure 1 In step S4, a random spread spectrum period is determined according to the spread frequency envelope function.

[0041] As an example, the first k Switching cycles for: in, For the k Switching cycle, i.e. random spread spectrum cycle, in units of s ; For the k The switching frequency is in Hz.

[0042] As an example, k Switching frequency It can be expressed as follows: in, R is a random number, the random number R The range of can include [0, 1]; is the current carrier ratio impact factor e n Maximum value of down-spread spectrum carrier frequency; is the current carrier ratio impact factor e n Minimum value of down-spread spectrum carrier frequency.

[0043] In yet another example, see Figure 3 , Figure 3 The distribution of random switching cycles after spectrum spread is shown in Figure 2, and the pulse width modulation PWM signals before and after randomization are compared. Figure 3 It can be seen that the pulse width modulation PWM signal before randomization is composed of a series of rectangular waves with different pulse widths. Each rectangular wave represents a PWM pulse, and the time intervals between adjacent pulses are represented by , , It means that these time intervals are fixed, which means that the switching period is constant before random processing and has no randomness. The pulse width modulation PWM signal after random processing is also composed of a series of rectangular waves, but the time interval between adjacent pulses becomes , , , these time intervals are different from those before randomization, and they no longer maintain a fixed relationship with each other, reflecting the randomness of the switching cycle after spread spectrum. From a fixed-cycle pulse width modulation PWM signal to a pulse width modulation PWM signal with a random switching cycle, this randomization changes the spectrum characteristics of the pulse width modulation PWM signal, which can effectively disperse energy and reduce the electromagnetic interference intensity at a specific frequency.

[0044] In step S5, refer to Figure 1 In step S5, modulation is implemented based on the random spread spectrum period to generate a drive signal to drive the permanent magnet motor.

[0045] As an example, the modulation may include space vector pulse width modulation (SVPWM).

[0046] In another example, space vector pulse width modulation (SVPWM) is an efficient motor control technology that can effectively improve the DC voltage utilization and motor performance. The random spread spectrum period is a value that changes randomly within a certain range, and the random spread spectrum period determines the periodic characteristics of the carrier signal in space vector pulse width modulation (SVPWM). Furthermore, according to the operating requirements of the motor, such as speed, torque command, etc., the position and size of the required reference voltage vector on the complex plane are calculated; the complex plane is divided into several sectors, and it is determined in which sector the reference voltage vector is located. Different sectors correspond to different basic voltage vector combinations, and which basic voltage vectors are used to synthesize the reference voltage vector is determined by sector judgment; the action time of each basic voltage vector in a random spread spectrum period is calculated by using the random spread spectrum period and the position of the reference voltage vector in the sector, and the action time can ensure that the synthesized voltage vector can approach the reference voltage vector; according to the obtained basic voltage vector action time, a corresponding pulse width modulation (PWM) signal is generated; by controlling the conduction and shutdown of the power switching device in the inverter, a pulse width modulation (PWM) waveform with a random spread spectrum period is output to realize the control of the permanent magnet motor.

[0047] It should be understood that, although the steps in the flowchart of the accompanying drawings are displayed in sequence as indicated by the arrows, these steps are not necessarily executed in sequence in the order indicated by the arrows. Unless otherwise specified herein, there is no strict order restriction on the execution of these steps, and these steps can be executed in other orders. Moreover, at least a portion of the steps in the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages are not necessarily executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages is not necessarily sequential, but can be executed in turn or alternately with other steps or at least a portion of the sub-steps or stages of other steps.

[0048] In the random modulation method for the permanent magnet motor servo drive system of the present application, by obtaining the real-time speed of the permanent magnet motor and setting parameters, the motor operation state can be accurately grasped, providing an accurate basis for subsequent control; based on the real-time speed, the carrier ratio and the carrier ratio influencing factor are determined, and the connection between the random modulation spread spectrum range and the motor speed is established. By dynamically adjusting the spread spectrum range under different carrier ratios, the spectrum energy can be more effectively dispersed and electromagnetic interference can be suppressed; using the carrier ratio influencing factor to construct the extended frequency envelope function and determine the random spread spectrum period, the periodic characteristics of the fixed switching frequency can be broken, the harmonic energy peak can be effectively dispersed, and the periodic characteristics of the fixed switching frequency can be broken, the harmonic energy peak can be effectively dispersed, and the interference intensity of the specific frequency can be further reduced; based on the random spread spectrum period, space vector pulse width modulation is realized. The method of the present application comprehensively considers the influence of the carrier ratio and the spread spectrum range on the motor control performance, reduces torque pulsation and current distortion, optimizes the motor control performance, enhances the system adaptability, improves the running stability and reliability, and provides strong support for the efficient application of permanent magnet motors in multiple fields.

[0049] In another embodiment, see Figure 4 The present application also provides a random modulation system for a permanent magnet motor servo drive system, which may include: a data acquisition module 10, a random carrier frequency generation module 20, and a modulation module 30. The data acquisition module 10 is used to obtain the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor; the random carrier frequency generation module 20 is used to obtain the carrier ratio, the carrier ratio influence factor, the extended frequency envelope function, and determine the random spread spectrum period based on the real-time speed of the permanent magnet motor and the parameters of the permanent magnet motor; the modulation module 30 is used to perform modulation according to the random spread spectrum period.

[0050] In the above-mentioned random modulation system for the permanent magnet motor servo drive system, the real-time speed of the permanent magnet motor is obtained and the parameters are set through the data acquisition module 10, which can provide accurate and practical basic data for subsequent operations, allowing the system to accurately grasp the motor operation status; the random carrier frequency generation module 20 obtains the carrier ratio, the carrier ratio influencing factor, the extended frequency envelope function and the random spread spectrum period, which can dynamically adjust the spread spectrum range, effectively disperse the spectrum energy, and reduce electromagnetic interference. The modulation module 30 performs modulation according to the random spread spectrum period, which can better adapt to the motor operation requirements. The system of this application can improve the control accuracy and stability of the permanent magnet motor servo drive system, optimize the performance of the permanent magnet motor, and provide technical support for the permanent magnet motor in a wider range of application scenarios, and promote the development of industrial automation and intelligence.

[0051] The technical features of the above embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] Although the present application has been disclosed as above with the embodiments, it is not intended to limit the present application. Any person with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be determined by the scope of the attached patent application.

Claims

1. A random modulation method for a permanent magnet motor servo drive system, characterized in that: The following steps are involved: Get the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor; Determine the carrier ratio based on the real-time speed of the permanent magnet motor, and obtain a carrier ratio influencing factor; constructing an extended frequency envelope function using the carrier ratio influence factor; Determining a random spread spectrum period according to the spread frequency envelope function; Modulation is achieved based on the random spreading period.

2. The random modulation method for a permanent magnet motor servo drive system according to claim 1, characterized in that: The carrier ratio N The expression is as follows: in, f T is the electrical frequency of the permanent magnet motor; f Z is the pulse width modulation carrier frequency.

3. The random modulation method for a permanent magnet motor servo drive system according to claim 2, characterized in that: Electrical frequency of permanent magnet motor f T The expression is as follows: in, n is the real-time speed of the permanent magnet motor, p is the number of pole pairs of the permanent magnet motor.

4. The random modulation method for a permanent magnet motor servo drive system according to claim 2, characterized in that: Carrier ratio impact factor e n The expression is as follows: in, N min is the minimum carrier ratio.

5. The random modulation method for a permanent magnet motor servo drive system according to claim 4, characterized in that: The expression of the extended frequency envelope function is as follows: ， in, is the carrier ratio influence factor e n The maximum value of the down-spread spectrum carrier frequency, is the carrier ratio influence factor e n The minimum value of the down-spread spectrum carrier frequency, is the minimum spread spectrum range, is the maximum spread spectrum range, f Z is the PWM carrier frequency.

6. The random modulation method for a permanent magnet motor servo drive system according to claim 5, characterized in that: The expression of random spreading period is as follows: in, For the k Random spread spectrum period of the switch; For the k A switching frequency.

7. The random modulation method for a permanent magnet motor servo drive system according to claim 6, characterized in that: No. k Switching frequency The expression is as follows: in, R is a random number, is the carrier ratio influence factor e n The maximum value of the down-spread spectrum carrier frequency, is the carrier ratio influence factor e n Minimum value of down-spread spectrum carrier frequency.

8. The random modulation method for a permanent magnet motor servo drive system according to claim 7, characterized in that: The random number R The range of variation includes [0, 1].

9. The random modulation method for a permanent magnet motor servo drive system according to claim 8, characterized in that: Modulation includes: Space Vector Pulse Width Modulation.

10. A random modulation system for a permanent magnet motor servo drive system, characterized in that: The random modulation method for a permanent magnet motor servo drive system according to any one of claims 1 to 9 comprises: Data acquisition module, used to obtain the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor; A random carrier frequency generation module is used to obtain a carrier ratio, a carrier ratio influence factor, an extended frequency envelope function, and determine a random spread spectrum period based on the real-time speed of the permanent magnet motor and the permanent magnet motor parameters; A modulation module is used to perform modulation according to the random spread spectrum period.

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