Random Modulation Method and System for Permanent Magnet Motor Servo Drive System

Abstract

The present invention discloses a random modulation method and system for a permanent magnet motor servo drive system, belonging to the technical field of motor control. The random modulation method for a permanent magnet motor servo drive system includes: obtaining the real-time speed of the permanent magnet motor and setting the parameters of the permanent magnet motor; determining the carrier ratio based on the real-time speed of the permanent magnet motor and obtaining the carrier ratio influence factor; constructing an extended frequency envelope function by using the carrier ratio influence factor; determining the random spread spectrum period according to the extended frequency envelope function; and implementing modulation based on the random spread spectrum period. The random modulation method for a permanent magnet motor servo drive system of the present invention comprehensively considers the influence of the carrier ratio and the spread spectrum range on the motor control performance, fully exerts the harmonic dispersion effect brought by the spread spectrum modulation, and effectively reduces the adverse influence of the traditional random modulation on the motor control performance under the condition of a low carrier ratio.

Description

Technical Field

[0001] The present invention relates to the technical field of motor control, and particularly 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 technologies, permanent magnet synchronous motor (PMSM) servo drive systems have been widely used in modern industries due to their high efficiency, high power density, and excellent dynamic performance. However, in traditional space vector pulse width modulation strategies, high-frequency operation of switching devices will generate serious electromagnetic interference, which affects system stability and interferes with surrounding equipment, making it difficult to meet electromagnetic compatibility requirements. Although traditional spread spectrum random modulation strategies can suppress electromagnetic interference, a large range of spread spectrum will increase torque ripple and current distortion, affecting the smooth operation and control accuracy of the motor. In addition, as the motor speed increases, using 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 this 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, this application provides a random modulation method for a permanent magnet motor servo drive system, including the following steps:

[0005] Obtain the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor;

[0006] Determine the carrier ratio based on the real-time speed of the permanent magnet motor to obtain a carrier ratio influence factor;

[0007] Construct an extended frequency envelope function using the carrier ratio influence factor;

[0008] Determine a random spread spectrum period according to the extended frequency envelope function;

[0009] Implement modulation based on the random spread spectrum period.

[0010] Optionally, the carrier ratio N has the following expression:

[0011]

[0012] where f T is the electrical frequency of the permanent magnet motor; f Z is the pulse width modulation carrier frequency.

[0013] Optionally, the electrical frequency of the permanent magnet motor f T is expressed as follows:

[0014]

[0015] where, n is the real-time speed of the permanent magnet motor, p is the number of pole pairs of the permanent magnet motor.

[0016] Optionally, the carrier ratio influence factor e n is expressed as follows:

[0017]

[0018] where, N min is the minimum carrier ratio.

[0019] Optionally, the expression of the extended frequency envelope function is as follows:

[0020] ,

[0021] where, is the carrier ratio influence factor e n the maximum value of the down-spread carrier frequency, is the carrier ratio influence factor e n the minimum value of the down-spread carrier frequency, is the minimum spread range, is the maximum spread range, f Z is the PWM carrier frequency.

[0022] Optionally, the expression of the random spread period is as follows:

[0023]

[0024] where, is the random spread period of the k th switch, is the k th switch frequency.

[0025] Optionally, the k th switch frequency is expressed as follows:

[0026]

[0027] where, R is a random number, is the carrier ratio influence factor e n The maximum value of the lower spread-spectrum carrier frequency, is the carrier ratio influence factor e n The minimum value of the lower spread-spectrum carrier frequency.

[0028] Optionally, the random number R has a variation range including [0, 1].

[0029] Optionally, the modulation includes: space vector pulse width modulation.

[0030] 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:

[0031] A data acquisition module, configured to obtain the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor;

[0032] A random carrier frequency generation module, configured to obtain the carrier ratio, the carrier ratio influence factor, the extended frequency envelope function based on the real-time speed of the permanent magnet motor and the parameters of the permanent magnet motor, and determine the random spread-spectrum period;

[0033] A modulation module, configured to perform modulation according to the random spread-spectrum period.

[0034] The present application provides a random modulation method and system for a permanent magnet motor servo drive system. By means of the carrier ratio and the carrier ratio influence factor, a connection is established between the random modulation spread-spectrum range and the speed of the permanent magnet motor servo system; by constructing the 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 spectral energy can be more effectively dispersed, taking into account both the suppression of electromagnetic interference and the optimization of the 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, the torque ripple and current distortion can be minimized to the greatest extent, thereby comprehensively improving the performance and reliability of the permanent magnet motor servo drive system; it can not only meet the control requirements of high precision and high efficiency, but also provide technical support for the permanent magnet motor in a wider range of application scenarios, promoting the development of industrial automation and intelligence.

[0035] To make the above features and advantages of the invention more obvious and understandable, specific embodiments are hereinafter given and described in detail in conjunction with the accompanying drawings as follows. Brief Description of the Drawings

[0036] To more clearly illustrate the technical solutions in the embodiments of the present application or related technologies, the following will briefly introduce the drawings required for the description of the embodiments or related technologies. Obviously, the drawings in the following description are only some embodiments of the present application. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0037] Figure 1 This is a flowchart of a random modulation method for a permanent magnet motor servo drive system provided in an embodiment of the present application.

[0038] Figure 2 This is an extended frequency envelope function diagram in the random modulation method for a permanent magnet motor servo drive system provided in an embodiment of the present application.

[0039] Figure 3 This is a random switching period distribution diagram in the random modulation method for a permanent magnet motor servo drive system provided in another embodiment of the present application.

[0040] Figure 4 This is 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 implementation manners

[0041] To make the objectives and technical solutions of the embodiments of the present application clearer, the following will clearly and completely describe the technical solutions of the embodiments of the present application in conjunction with the drawings of the embodiments of the present application. Obviously, the described embodiments are some, but not all, of the embodiments of the present application. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present application without creative efforts belong to the scope of protection of the present application.

[0042] In one embodiment, please refer to 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.

[0043] Step S1: Obtain the real-time speed of the permanent magnet motor and set the parameters of the permanent magnet motor.

[0044] Step S2: Determine the carrier ratio based on the real-time speed of the permanent magnet motor to obtain the carrier ratio influence factor.

[0045] Step S3: Use the carrier ratio influence factor to construct an extended frequency envelope function.

[0046] Step S4: Determine the random frequency spreading period according to the extended frequency envelope function.

[0047] Step S5: Implement modulation based on the random spreading period to generate a driving signal and achieve the driving of the permanent magnet motor.

[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 operating state of the motor can be accurately grasped; based on the real-time speed of the permanent magnet motor, the carrier ratio and the carrier ratio influence factor are determined, and the connection between the random modulation spreading range and the speed of the permanent magnet motor servo system can be established. By dynamically adjusting the spreading range at different carrier ratios, the spectral 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 ripple 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.

[0049] In step S1, refer to Figure 1 step S1 in

[0050] As an example, the real-time speed of the permanent magnet motor can be obtained by two methods: with sensors and without sensors. The sensors may include: speed sensors such as Hall sensors, optical encoders, and resolvers. Specifically, the Hall sensor obtains the real-time speed of the permanent magnet motor by monitoring the magnetic field change; the optical sensor uses the principle of photoelectric conversion to convert the angular displacement of the permanent magnet motor into an electrical pulse signal, thereby obtaining the speed. These speed sensors can convert the mechanical rotational motion of the permanent magnet motor into electrical signals, providing accurate data for subsequent control algorithms, enabling the control system to adjust the control strategy in a timely manner according to the actual state of the motor, and thus improving the control accuracy of the motor.

[0051] Furthermore, the parameters of the permanent magnet motor can be set by means of the nameplate of the permanent magnet motor, reference manual, experimental measurement, empirical value, etc. The parameters of the permanent magnet motor may include: basic parameters such as maximum speed, number of pole pairs, rated voltage, rated current, rated power, stator resistance, stator inductance, magnetic flux, moment of inertia, rated speed, etc. Further calculate the electrical frequency of the motor based on the maximum speed and the number of pole pairs.

[0052] In step S2, refer to Figure 1 step S2 in

[0053] 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 , and the following formula can be used:

[0054]

[0055] wheref T is the electrical frequency of the permanent magnet motor, which is the same as the modulation wave frequency, with the unit of Hz; n is the obtained real-time speed of the permanent magnet motor, with the unit of r / min; p is the number of pole pairs of the permanent magnet motor.

[0056] Furthermore, the carrier ratio N is:

[0057]

[0058] wherein, f T is the electrical frequency of the permanent magnet motor, which is the same as the modulation wave frequency, with the unit of Hz; f Z is the PWM carrier frequency, with the unit of Hz.

[0059] Furthermore, according to the electrical frequency f T formula and the carrier ratio N formula, it can be known that when the real-time speed n of the permanent magnet motor is the maximum value, there is a minimum carrier ratio N min , then the carrier ratio influence factor e n is:

[0060]

[0061] wherein, e n is the carrier ratio influence factor, and its value range is (0, 1]; N min is the minimum carrier ratio.

[0062] In step S3, please refer to Figure 1 step S3 in, and use the carrier ratio influence factor to construct an extended frequency envelope function.

[0063] As an example, the expression of the extended frequency envelope function is as follows:

[0064] ,

[0065] wherein, is the current carrier ratio influence factor e n the maximum value of the spread spectrum carrier frequency, is the current carrier ratio influence factor e n the minimum value of the spread spectrum carrier frequency, is the minimum spread spectrum range, is the maximum spreading range, f Z is the PWM carrier frequency.

[0066] As an example, the maximum spreading range can take a value of 40%, and the minimum spreading range can take a value of 10%.

[0067] In one example, refer to Figure 2 , Figure 2 , is the extended frequency envelope function formed under a certain spreading range, where the abscissa represents the carrier ratio influence factor; the ordinate 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, at the current carrier ratio influence factor , the maximum value that the spread spectrum carrier frequency can reach; the lower curve is the lower limit of the extended frequency envelope function, that is, at the current carrier ratio influence factor , the minimum value that the spread spectrum carrier frequency can reach. The middle line represents the value range of the spread spectrum carrier frequency between the upper and lower limits under different carrier ratio influence factors. It can be seen from Figure 2 that as the carrier ratio influence factor changes, the spread spectrum carrier frequency fluctuates within the upper and lower limits, reflecting the constraint and modulation effect of the extended 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 under this spreading range.

[0068] In step S4, refer to step S4 in Figure 1 to determine the random spreading period according to the extended frequency envelope function.

[0069] As an example, according to the extended frequency envelope function, the k th switching period is:

[0070]

[0071] where, is the k th switching period, that is, the random spreading period, with the unit of s ; is the k th switching frequency, with the unit of Hz.

[0072] As an example, the k th switching frequency can be expressed by the following formula:

[0073]

[0074] Among them, R is a random number, and the variation range of the random number R can include [0, 1]; is the current carrier ratio influence factor e n The maximum value of the lower spread-spectrum carrier frequency; is the current carrier ratio influence factor e n The minimum value of the lower spread-spectrum carrier frequency.

[0075] In yet another example, please refer to Figure 3 , Figure 3 is the distribution of the random switching period after spreading, and the pulse-width modulation PWM signals before and after randomization are compared. It can be seen from Figure 3 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 , , respectively. These time intervals are fixed, which means that the switching period is constant before random processing and does not have randomness. The pulse-width modulation PWM signal after randomization is also composed of a series of rectangular waves, but the time intervals between adjacent pulses become , , respectively. These time intervals are different from those before randomization and no longer maintain a fixed relationship with each other, reflecting the randomness of the switching period after spreading. The transformation from a pulse-width modulation PWM signal with a fixed period to a pulse-width modulation PWM signal with a random switching period changes the spectral characteristics of the pulse-width modulation PWM signal, can effectively disperse energy, and reduce the electromagnetic interference intensity at specific frequencies.

[0076] In step S5, please refer to step S5 in Figure 1 , and modulation is implemented based on the random spreading period to generate a driving signal to drive the permanent magnet motor.

[0077] As an example, the modulation may include: space vector pulse width modulation (SVPWM).

[0078] In another example, Space Vector Pulse Width Modulation (SVPWM) is an efficient motor control technology that can effectively improve the utilization rate of DC voltage and the operating performance of the motor. The random spreading period is a value that randomly varies within a certain range, and the random spreading period determines the periodic characteristics of the carrier signal in Space Vector Pulse Width Modulation (SVPWM). Further, according to the operating requirements of the motor, such as rotational speed, torque command, etc., the position and magnitude of the required reference voltage vector in the complex plane are calculated; the complex plane is divided into several sectors, and it is determined which sector the reference voltage vector is located in. Different sectors correspond to different combinations of basic voltage vectors, and by sector determination, it is determined which basic voltage vectors are used to synthesize the reference voltage vector; using the random spreading period and the position of the reference voltage vector within the sector, the action time of each basic voltage vector within a random spreading period is calculated, and the action time can ensure that the synthesized voltage vector can approximate the reference voltage vector; according to the obtained action time of the basic voltage vectors, corresponding Pulse Width Modulation (PWM) signals are generated; by controlling the conduction and cutoff of the power switching devices in the inverter, a Pulse Width Modulation (PWM) waveform with a random spreading period is output to achieve the control of the permanent magnet motor.

[0079] It should be understood that although the steps in the flowchart of the accompanying drawings are shown sequentially according to the indication of the arrows, these steps do not necessarily have to be executed sequentially according to the order indicated by the arrows. Unless there is a clear indication in this article, there is no strict order restriction for the execution of these steps, and these steps can be executed in other orders. Moreover, at least a part of the steps in the accompanying drawings may include multiple sub-steps or multiple stages, and these sub-steps or stages do not necessarily have to be executed at the same time, but can be executed at different times, and the execution order of these sub-steps or stages does not necessarily have to be sequential, but can be executed alternately or in turn with at least a part of other steps or sub-steps or stages of other steps.

[0080] 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 operating state of the motor can be accurately grasped, providing an accurate basis for subsequent control; based on the real-time speed, the carrier ratio and the carrier ratio influence factor are determined, establishing the relationship between the random modulation spread spectrum range and the motor speed. By dynamically adjusting the spread spectrum range at different carrier ratios, the spectrum energy can be more effectively dispersed, suppressing electromagnetic interference; using the carrier ratio influence factor to construct an extended frequency envelope function and determine the random spread spectrum period can break the periodic characteristics of the fixed switching frequency, effectively dispersing the peak value of the harmonic energy, and can break the periodic characteristics of the fixed switching frequency, effectively dispersing the peak value of the harmonic energy, further reducing the interference intensity at specific frequencies; space vector pulse width modulation is implemented based on the random spread spectrum period. 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 ripple and current distortion, optimizes the motor control performance, enhances the system adaptability, improves the operation stability and reliability, and provides strong support for the efficient application of permanent magnet motors in multiple fields.

[0081] In another embodiment, please refer to 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. Among them, 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.

[0082] In the above random modulation system for the permanent magnet motor servo drive system, by using the data acquisition module 10 to obtain the real-time speed of the permanent magnet motor and set parameters, accurate and practical basic data can be provided for subsequent operations, enabling the system to accurately grasp the operating state of the motor; the random carrier frequency generation module 20 obtains the carrier ratio, the carrier ratio influence 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 operating requirements of the motor. The system of the present 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 also provide technical support for the permanent magnet motor in a wider range of application scenarios, promoting the development of industrial automation and intelligence.

[0083] The technical features of the above embodiments can be combined arbitrarily. For the sake of concise description, 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, it should be considered as the scope recorded in this specification.

[0084] Although the present application has been disclosed above by way of examples, it is not intended to limit the present application. Any person with ordinary knowledge in the relevant technical field may make some modifications and refinements without departing from the spirit and scope of the present application. Therefore, the scope of protection of the present application shall be subject to that defined by the appended claims for 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; The carrier ratio is determined based on the real-time speed of the permanent magnet motor. The expression of the carrier ratio is as follows: ， Where N is the carrier ratio, f T is the electrical frequency of the permanent magnet motor, f Z is the pulse width modulation carrier frequency; the carrier ratio influence factor is obtained according to the carrier ratio, and the expression of the carrier ratio influence factor is as follows: ， Among them, e n is the carrier ratio influence factor, N min is the minimum carrier ratio; The carrier ratio influence factor is used to construct an extended frequency envelope function, and 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, is the PWM carrier frequency; The random spreading period is determined according to the spread frequency envelope function, and the expression of the random spreading period is as follows: in, is the random spread spectrum period of the kth switch, is the kth switching frequency; 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 electrical frequency f of the permanent magnet motor T The expression is as follows: Among them, n is the real-time speed of the permanent magnet motor, and p is the number of pole pairs of the permanent magnet motor.

3. The random modulation method for a permanent magnet motor servo drive system according to claim 1, characterized in that: kth switching frequency The expression is as follows: Among them, R is a random number, is the carrier ratio influence factor The maximum value of the down-spread spectrum carrier frequency, is the carrier ratio influence factor Minimum value of down-spread spectrum carrier frequency.

4. The random modulation method for a permanent magnet motor servo drive system according to claim 3, characterized in that: The random number R ranges from [0, 1].

5. The random modulation method for a permanent magnet motor servo drive system according to claim 4, characterized in that: Modulation includes: Space Vector Pulse Width Modulation.

6. 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 5 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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