Method and system for adjusting speed of variable frequency driving motor by controller

Abstract

The invention provides a method and system for adjusting the speed of a variable-frequency driving motor through a controller, and relates to the technical field of speed regulation control, and the method comprises the steps: constructing a planetary gear train coupling structure based on the dual-motor power of a frequency converter; establishing two-wire communication connection by adopting a ModBus communication protocol, and dynamically acquiring real-time operation data of the frequency converter; the real-time operation data is dynamically analyzed through a PID controller, and a real-time speed regulation decision is obtained in combination with a predetermined load response strategy; and performing speed regulation control on the planetary gear train coupling structure according to the real-time speed regulation decision. According to the invention, the technical problem of low speed regulation control precision of the motor in the prior art can be solved, the technical targets of quick response, precise speed regulation and efficient energy distribution of the motor under different load working conditions are achieved, and the technical effect of improving the speed regulation control precision of the motor is achieved.

Description

Technical Field

[0001] This application relates to the field of speed control technology, and in particular to a method and system for a controller to adjust the speed of a variable frequency drive motor. Background Technology

[0002] With the continuous improvement of industrial automation, frequency converter-driven motor systems are widely used in various mechanical equipment to achieve efficient and energy-saving speed regulation and precise control. However, traditional single-motor drive systems have significant shortcomings when dealing with complex load changes. For example, under constant torque or quadratic load conditions, the output power and response speed of a single motor are difficult to meet the rapidly changing operating conditions, and are prone to speed drop, overshoot, or oscillation, affecting production efficiency and equipment life.

[0003] In summary, existing technologies suffer from a lack of multi-motor collaborative control and the ability to dynamically analyze real-time operating data. This results in low motor speed control accuracy and slow response speed under complex load variations, further impacting the stable operation, production efficiency, and service life of production equipment. Summary of the Invention

[0004] The purpose of this application is to provide a method and system for a controller to adjust the speed of a variable frequency drive motor, in order to solve the technical problems in the prior art where the lack of multi-motor coordinated control and the ability to dynamically analyze real-time operating data leads to low motor speed control accuracy and slow response speed under complex load changes, which further affects the stable operation, production efficiency and service life of production equipment.

[0005] In view of the above problems, this application provides a method and system for a controller to adjust the speed of a variable frequency drive motor.

[0006] In a first aspect, this application provides a method for a controller to adjust the speed of a variable frequency drive motor. The system implementation of adjusting the speed of a variable frequency drive motor through a controller includes: constructing a planetary gear train coupling structure based on the dual-motor power of the frequency converter; establishing a two-wire communication connection using the ModBus communication protocol and dynamically acquiring real-time operating data of the frequency converter; dynamically analyzing the real-time operating data through a PID controller and obtaining a real-time speed regulation decision in combination with a predetermined load response strategy; and performing speed regulation control on the planetary gear train coupling structure according to the real-time speed regulation decision.

[0007] Preferably, the method for the controller to adjust the speed of the variable frequency drive motor further includes: the main motor is connected to the internal gear ring of the planetary gear train through a first reduction gear, and the variable frequency motor is connected to the sun gear of the planetary gear train through a second reduction gear, forming the planetary gear train coupling structure; wherein, the planet carrier of the planetary gear train serves as the output end to synthesize the dual motor speed of the dual motor power.

[0008] Preferably, the method for the controller to adjust the speed of the variable frequency drive motor further includes: the main motor is a three-phase asynchronous motor running at a rated speed, and the variable frequency motor is a permanent magnet synchronous motor whose speed is adjusted by the frequency converter; wherein, the power ratio of the main motor to the variable frequency motor is (1.5~2.5):1.

[0009] Preferably, the method for the controller to adjust the speed of the variable frequency drive motor further includes: locating abnormal noise points in the real-time operating data that exceed the baseline equilibrium point; filtering the abnormal noise points based on low-pass filtering to obtain a reconstructed operating waveform, and using the reconstructed operating waveform as input information for the PID controller; wherein, the abnormal noise points include amplitude abnormal noise points and frequency abnormal noise points.

[0010] Preferably, the method for the controller to adjust the speed of the variable frequency drive motor further includes: obtaining real-time key features based on the reconstructed operating waveform, and inputting the real-time key features into the PID controller to obtain the real-time speed regulation decision; wherein the real-time key features include at least the stator winding current fluctuation mode, the rotor copper loss transient value, and the core loss steady-state value.

[0011] Preferably, the method for adjusting the speed of the variable frequency drive motor by the controller further includes: obtaining the real-time rotational speed based on the real-time key features, and comparing the real-time rotational speed with a predetermined rotational speed to obtain a real-time rotational speed deviation; performing time-series analysis on the real-time rotational speed deviation to obtain the deviation change rate, and forming a linguistic variable with the real-time rotational speed deviation; matching the target parameter combination corresponding to the linguistic variable in the fuzzy control rule base, and determining the real-time speed adjustment decision based on the target parameter combination; wherein, when the load changes abruptly, the integral parameter is automatically strengthened to suppress speed overshoot.

[0012] Preferably, the method for the controller to adjust the speed of the variable frequency drive motor further includes: the predetermined load response strategy refers to switching to dual-motor joint drive when the real-time speed is lower than 50%-60% of the predetermined speed for constant torque load, and enabling the variable frequency motor to compensate for speed when the real-time speed is lower than 65%-75% of the predetermined speed for quadratic load.

[0013] Preferably, the method for the controller to adjust the speed of the variable frequency drive motor further includes: when the load is at the rated load, if the real-time speed is lower than 59% of the predetermined speed, the dual-motor joint drive mode is automatically started; when the load is reduced to no load, if the real-time speed is lower than 64% of the predetermined speed, the dual-motor joint drive mode is started in advance.

[0014] Preferably, the method for adjusting the speed of the variable frequency drive motor by the controller further includes: when the real-time speed drops below 78% of the predetermined speed, the variable frequency motor switches to forward rotation mode; when the real-time speed is higher than 78% of the predetermined speed, the variable frequency motor switches to reverse rotation mode; wherein, the compensation amount is dynamically optimized based on the torque-speed square relationship of the quadratic load analyzed by the linguistic variables of the PID controller.

[0015] Secondly, this application also provides a system for a controller to adjust the speed of a variable frequency drive motor, used to execute the method for adjusting the speed of a variable frequency drive motor as described in the first aspect, comprising: a planetary gear train coupling structure construction module for constructing a planetary gear train coupling structure based on the dual-motor power of the frequency converter; a real-time operating data acquisition module for establishing a two-wire communication connection using the ModBus communication protocol and dynamically acquiring the real-time operating data of the frequency converter; a real-time speed regulation decision acquisition module for dynamically analyzing the real-time operating data through a PID controller and obtaining a real-time speed regulation decision in conjunction with a predetermined load response strategy; and a speed regulation control module for performing speed regulation control on the planetary gear train coupling structure according to the real-time speed regulation decision.

[0016] The technical solution provided in this application has at least the following technical effects or advantages: by achieving the technical goals of rapid motor response, precise speed regulation and efficient energy distribution under different load conditions, it achieves the technical effects of improving system stability, reducing energy consumption, extending equipment service life and optimizing production efficiency.

[0017] The above description is merely an overview of the technical solution of this application. To enable a clearer understanding of the technical means of this application and to facilitate its implementation according to the description, and to make the above and other objects, features, and advantages of this application more apparent, specific embodiments of this application are described below. It should be understood that the content described in this section is not intended to identify key or important features of the embodiments of this application, nor is it intended to limit the scope of this application. Other features of this application will become readily apparent through the following description. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are merely exemplary. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0019] Figure 1 This is a flowchart illustrating the method for adjusting the speed of a variable frequency drive motor using the controller in this application.

[0020] Figure 2 This is a schematic diagram of the system for adjusting the speed of a variable frequency drive motor using the controller of this application.

[0021] Figure labeling: Planetary gear train coupling structure construction module 1, real-time operation data acquisition module 2, real-time speed regulation decision acquisition module 3, speed regulation control module 4. Detailed Implementation

[0022] This application provides a method and system for regulating the speed of a variable frequency drive motor using a controller. This solves the technical problems in existing technologies where the lack of multi-motor coordinated control and dynamic analysis of real-time operating data leads to low motor speed control accuracy and slow response speed under complex load variations, further affecting the stable operation, production efficiency, and service life of production equipment. The application achieves the technical goals of rapid motor response, precise speed regulation, and efficient energy distribution under different load conditions, thereby improving system stability, reducing energy consumption, extending equipment life, and optimizing production efficiency.

[0023] The technical solutions of this application will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. It should be understood that this application is not limited to the exemplary embodiments described herein. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application. It should also be noted that, for ease of description, only the parts related to this application are shown in the accompanying drawings, not all of them.

[0024] Example 1, please refer to the appendix. Figure 1 This application provides a method for a controller to adjust the speed of a variable frequency drive motor, which is applied to a system where the controller adjusts the speed of a variable frequency drive motor, and specifically includes the following steps: S1: A planetary gear train coupling structure based on a dual-motor power system using a frequency converter.

[0025] Specifically, the system utilizes a dual-motor power system based on a frequency converter to construct a planetary gear coupling structure. This structure combines the power of two motors through a planetary gear mechanism. The dual-motor power system refers to a main motor and a variable frequency motor jointly providing driving force. The main motor maintains stable operation, while the variable frequency motor adjusts its speed by regulating the current frequency and voltage through the frequency converter. A planetary gear system is a gear transmission structure composed of a sun gear, planet gears, an internal gear ring, and a planet carrier. It is characterized by its small size, large transmission ratio, and high load-bearing capacity. The coupling structure represents the combination of the torque and speed of two different power sources into a unified output through the planetary gear system. By organically combining the power of the main motor and the variable frequency motor using the planetary gear system structure, the entire system can ensure a stable main force output while allowing for flexible adjustment through the variable frequency motor, thus achieving efficient transmission.

[0026] S2: A two-wire communication connection is established using the ModBus communication protocol, and the real-time operating data of the frequency converter is dynamically acquired.

[0027] Specifically, a two-wire communication connection is established using the ModBus communication protocol to dynamically acquire real-time operating data from the frequency converter, enabling data interaction between the control system and the frequency converter for subsequent analysis and adjustment by the controller. The ModBus communication protocol is a serial communication protocol used in industrial automation, ensuring reliable and efficient data transmission between different devices. A two-wire communication connection uses only two wires for data transmission and reception; this method is simple in structure, low in cost, and suitable for stable data transmission in electrical equipment. Real-time operating data refers to the instantaneous information continuously generated by the frequency converter during actual operation, such as parameters like voltage, current, frequency, speed, and temperature. This dynamically reflects the motor's operating status and is collected by the host computer or control system.

[0028] S3: The real-time operating data is dynamically analyzed by the PID controller, and a real-time speed regulation decision is obtained by combining the predetermined load response strategy.

[0029] Specifically, a PID controller dynamically analyzes real-time operating data. The PID controller, composed of proportional, integral, and derivative control parameters, continuously calculates and adjusts real-time data such as current, voltage, and speed collected during motor operation. The PID controller is a feedback control tool. The proportional term directly corrects the output based on the magnitude of the deviation, the integral term eliminates accumulated deviations over time, and the derivative term predicts trends to prevent system overshoot. For example, when the speed is 50 rpm lower than the target value, the proportional term immediately adjusts the output, the integral term continuously compensates, and the derivative term suppresses fluctuations caused by excessive acceleration.

[0030] The real-time speed regulation decision is obtained by combining a predetermined load response strategy, which explains that the final speed regulation method is determined by superimposing a pre-designed load response method on top of PID calculation. The predetermined load response strategy refers to the regulation rules set according to different load types. For example, constant torque loads require more compensation at low speeds, while quadratic loads consume more energy at medium and high speeds. Therefore, the PID controller will adopt different force-increasing or force-reducing schemes under different operating conditions.

[0031] S4: Speed ​​control is performed on the planetary gear train coupling structure based on the real-time speed control decision.

[0032] Specifically, speed control is performed on the planetary gear train coupling structure based on real-time speed control decisions. That is, after receiving the speed control decision calculated by the controller, the motor system applies the decision to the planetary gear train, a mechanical transmission structure, thereby adjusting the output speed. Speed ​​control refers to changing the output characteristics of the variable frequency motor or main motor under the guidance of real-time speed control decisions, so that the speed of the planetary carrier at the output end meets the target requirements.

[0033] Furthermore, this application also includes: the dual-motor power includes a main motor and a variable frequency motor, and the dual-motor power based on the variable frequency motor constructs a planetary gear train coupling structure, including: the main motor is connected to the internal gear ring of the planetary gear train through a first reduction gear, and the variable frequency motor is connected to the sun gear of the planetary gear train through a second reduction gear, forming the planetary gear train coupling structure; wherein, the planet carrier of the planetary gear train serves as the output end to synthesize the dual-motor speed of the dual-motor power.

[0034] Specifically, dual-motor power refers to a system in which two motors jointly provide driving force. Dual-motor power includes a main motor and a variable frequency motor. The main motor is a fixed-speed motor with a large rated power, which is used to bear the main load, while the variable frequency motor is a motor whose speed is adjusted by a frequency converter, which is used to flexibly compensate for load changes, thereby achieving optimized output of overall power.

[0035] The dual-motor power system based on the frequency converter constructs a planetary gear coupling structure, which connects the outputs of the main motor and the frequency converter motor through a mechanical device. The mechanical device is a planetary gear system, which is a planetary gear structure composed of a sun gear, planet gears and an internal gear ring. It can combine the speed and torque of the two motors to achieve coordinated drive.

[0036] The main motor is connected to the internal gear ring of the planetary gear system through the first reduction gear. This means that the high-speed rotation output of the main motor is first reduced in speed by the reduction gear before being transmitted to the internal gear ring of the planetary gear system. The function of the reduction gear is to convert the high-speed, low-torque motor output into a speed and torque suitable for the planetary gear system, thereby ensuring transmission efficiency and stability.

[0037] The variable frequency motor is connected to the sun gear of the planetary gear train through the second reduction gear. This means that the output of the variable frequency motor is transmitted to the sun gear after the speed is adjusted by another set of reduction gears. The sun gear is the central gear in the planetary gear train. Through the current connection method, the variable frequency motor can flexibly adjust the speed compensation of the entire coupling structure, and can respond quickly, especially when the load changes suddenly.

[0038] The main motor and the variable frequency motor drive the internal gear ring and the sun gear respectively through their respective gears, forming a planetary gear coupling structure. This enables the synthesis and distribution of power in the planetary gear system, allowing the two motors to work together and output a smooth and adjustable speed.

[0039] The planetary carrier of the planetary gear train serves as the output end to synthesize the dual-motor power and achieve the dual-motor speed. This means that the planetary carrier of the planetary gear train, as the output part of the entire mechanical transmission, combines the power of the main motor and the variable frequency motor into a whole output speed. For example, when the main motor outputs at 1500 rpm and the variable frequency motor outputs at 1200 rpm, through the distribution of the planetary gear train, the planetary carrier may obtain a combined speed of 1350 rpm, thus ensuring both load requirements and smooth power transition.

[0040] Furthermore, this application also includes: the main motor is a three-phase asynchronous motor that operates at its rated speed, and the variable frequency motor is a permanent magnet synchronous motor whose speed is adjusted by the frequency converter; wherein, the power ratio of the main motor to the variable frequency motor is (1.5~2.5):1.

[0041] Specifically, the main motor is a three-phase asynchronous motor that operates at its rated speed. That is, the main motor is powered by three-phase AC power and generates a rotating magnetic field through electromagnetic induction, causing the rotor to rotate following the magnetic field. The speed of the asynchronous motor is slightly lower than the synchronous speed corresponding to the grid frequency. The rated speed refers to the stable speed of the motor under rated voltage and rated load, such as 1500 revolutions per minute. When the load does not change much, the main motor maintains a constant speed to output stable power.

[0042] The variable frequency motor is a permanent magnet synchronous motor. The speed is adjusted by the frequency converter, which means that the variable frequency motor contains a permanent magnet rotor. The frequency converter changes the frequency and voltage of the input power supply, thereby adjusting the motor speed. The permanent magnet synchronous motor has high efficiency and high response speed, and can quickly adjust the output according to the load change. For example, when the load increases, the frequency converter can increase the motor speed from 1200 rpm to 1500 rpm to compensate for insufficient power.

[0043] The power ratio of the main motor to the variable frequency motor is (1.5~2.5):1, which means that the output power of the main motor is approximately 1.5 to 2.5 times that of the variable frequency motor. Through the power ratio, the main motor undertakes the main constant load, while the variable frequency motor undertakes the variable load and compensation tasks. For example, when the output power of the main motor is 30 kW, the output power of the variable frequency motor is between 12 kW and 20 kW, so as to ensure that the overall power output is both stable and flexible.

[0044] Furthermore, this application also includes: locating abnormal noise points in the real-time operating data that exceed the baseline equilibrium point; filtering the abnormal noise points based on low-pass filtering to obtain a reconstructed operating waveform, and using the reconstructed operating waveform as input information for the PID controller; wherein, the abnormal noise points include amplitude abnormal noise points and frequency abnormal noise points.

[0045] Specifically, it involves locating abnormal noise points in real-time operating data that exceed the baseline equilibrium point. This means identifying numerical points in the real-time operating data collected from the frequency converter that do not conform to the normal fluctuation range. The baseline equilibrium point refers to the reference value under stable operating conditions, such as the stable average level of current, voltage, or speed. Abnormal noise points refer to abnormal data points that momentarily exceed this reference level. Abnormal noise points may be caused by electromagnetic interference, sudden load changes, or measurement errors and need to be identified before analysis.

[0046] The reconstructed operating waveform is obtained by filtering abnormal noise using low-pass filtering. This demonstrates that after identifying abnormal noise, high-frequency interference components are removed by low-pass filtering digital signal processing, while retaining the main low-frequency characteristics. The reconstructed operating waveform is then used as input information for the PID controller, resulting in a smoother waveform that more closely approximates the actual operating conditions. The reconstructed operating waveform is essentially a new data curve obtained after noise removal, enabling more accurate and reliable subsequent speed control decisions.

[0047] Abnormal noise includes amplitude abnormal noise and frequency abnormal noise. Amplitude abnormal noise refers to points where the signal amplitude is suddenly too high or too low, such as the current jumping from 10 amps to 20 amps in an instant. Frequency abnormal noise refers to unreasonable rapid fluctuations in the signal, such as the speed suddenly jumping from 1500 rpm to 1700 rpm and then dropping back to 1500 rpm within 1 second. Abnormal noise can mislead the controller's judgment and therefore must be filtered out.

[0048] Furthermore, this application also includes: obtaining real-time key features based on the reconstructed operating waveform, and inputting the real-time key features into the PID controller to obtain the real-time speed regulation decision; wherein the real-time key features include at least the stator winding current fluctuation mode, the rotor copper loss transient value, and the core loss steady-state value.

[0049] Specifically, real-time key features are obtained based on the reconstructed operating waveform. This involves extracting the main characteristic parameters representing the motor's operating state from the filtered waveform; these are called real-time key features and reflect the instantaneous changes in load, speed, and energy consumption. These real-time key features are then input to a PID controller. The PID controller calculates a suitable speed control scheme based on the input information, resulting in a real-time speed control decision. This makes the motor's operation more stable and efficient. For example, when current fluctuations increase, the PID controller automatically adjusts its output to compensate for the deviation.

[0050] Among them, the real-time key features include at least the stator winding current fluctuation mode, the rotor copper loss transient value, and the core loss steady-state value. The stator winding current fluctuation mode refers to the change law of the motor stator winding current during operation, which can reflect the load change and the stress on the motor. The rotor copper loss transient value refers to the magnitude of the instantaneous change of copper loss generated by the motor rotor current, which can reflect the loss characteristics of the motor when the load changes suddenly. The core loss steady-state value represents the energy loss of the motor core due to hysteresis and eddy current during long-term stable operation, reflecting the long-term performance of the overall efficiency of the motor.

[0051] Furthermore, this application also includes: the PID controller has an embedded fuzzy control rule base, real-time key features are obtained based on the reconstructed operating waveform, and the real-time key features are input to the PID controller to obtain the real-time speed regulation decision, including: obtaining the real-time speed based on the real-time key features, and comparing the real-time speed with a predetermined speed to obtain the real-time speed deviation; performing time-series analysis on the real-time speed deviation to obtain the deviation change rate, and forming a linguistic variable with the real-time speed deviation; matching the target parameter combination corresponding to the linguistic variable in the fuzzy control rule base, and determining the real-time speed regulation decision based on the target parameter combination; wherein, when the load changes abruptly, the integral parameter is automatically strengthened to suppress speed overshoot.

[0052] Specifically, the PID controller incorporates a fuzzy control rule base. Real-time key features are obtained from the reconstructed operating waveform and input into the PID controller to obtain real-time speed control decisions. This demonstrates that fuzzy control methods have been added to the traditional PID controller. The PID controller is a classic control algorithm composed of proportional, integral, and derivative components, primarily used to correct system deviations. The fuzzy control rule base transforms imprecise information into control rules through a process similar to human logical judgment, enhancing the adaptability of the PID controller. Therefore, when the key features extracted from the reconstructed operating waveform are input, the PID controller not only relies on mathematical calculations but can also combine fuzzy logic to obtain a more flexible speed control scheme.

[0053] The real-time rotational speed can be calculated based on some parameters in the real-time key features. The real-time rotational speed refers to the actual speed of the motor under the current operating conditions. The real-time rotational speed is compared with the predetermined speed to obtain the real-time rotational speed deviation. The predetermined speed is the target speed set according to design or task requirements. The real-time rotational speed deviation is the difference between the two, reflecting the gap between the current operating state of the motor and the ideal state.

[0054] Time-series analysis of the real-time speed deviation yields the deviation change rate, which represents the rate at which the deviation increases or decreases over a certain time period. The deviation change rate and the real-time speed deviation together constitute a linguistic variable. Linguistic variables are an abstract expression used in fuzzy control; for example, the deviation can be described as large, medium, or small, and the change rate can be described as fast, moderate, or slow, used to enable the PID controller to perform fuzzy inference.

[0055] In the fuzzy control rule base, the target parameter combination corresponding to the linguistic variable is matched, and the real-time speed regulation decision is determined based on the target parameter combination. This means that when the linguistic variable is determined, the PID controller will find the corresponding control parameters in the fuzzy control rule base, such as the combination of proportional coefficient, integral coefficient and derivative coefficient, and then use the corresponding parameters to calculate the most suitable speed regulation scheme under the current situation, so as to make the motor run more smoothly.

[0056] When the load changes abruptly, the integral parameter is automatically enhanced to suppress speed overshoot. A sudden load change refers to a sudden and drastic change in the load on the motor, which can easily cause the speed to deviate from the target value or even exceed the expectation. The main function of the integral parameter in the PID controller is to eliminate long-term accumulated errors. When a sudden change occurs, the integral action is automatically enhanced, which can quickly suppress the overshoot phenomenon and bring the motor back to a stable state.

[0057] Furthermore, this application also includes: the predetermined load response strategy refers to switching to dual-motor joint drive when the real-time speed is lower than 50%-60% of the predetermined speed for constant torque load, and enabling the variable frequency motor to compensate for speed when the real-time speed is lower than 65%-75% of the predetermined speed for quadratic load.

[0058] Specifically, the predetermined load response strategy refers to switching to dual-motor joint drive when the real-time speed is 50%-60% lower than the predetermined speed for constant torque loads. This means that a solution has been designed in advance to deal with different load characteristics. Constant torque loads refer to loads where the torque required by the load remains constant regardless of the speed change, such as conveyor belts or extruders. Therefore, if the actual speed of the motor drops too much, such as to half of the target speed, it is necessary to have the main motor and the variable frequency motor work simultaneously, i.e., dual-motor joint drive, to provide a greater combined output, thereby ensuring that the equipment continues to operate stably.

[0059] For quadratic loads, when the real-time speed is lower than 65%-75% of the predetermined speed, the variable frequency motor is activated to compensate for the speed. The torque of a quadratic load is proportional to the square of the speed. When the speed decreases, the load torque decreases even faster. Therefore, the system's trigger threshold is higher than that for constant torque loads. When the speed is lower than about two-thirds of the target value, the variable frequency motor will be activated for speed compensation to maintain efficiency while avoiding overload of the main motor.

[0060] Furthermore, this application also includes: when the load size is the rated load, if the real-time speed is lower than 59% of the predetermined speed, the dual-motor joint drive mode is automatically started; when the load size is reduced to no load, if the real-time speed is lower than 64% of the predetermined speed, the dual-motor joint drive mode is started in advance.

[0061] Specifically, a trigger point is set under full-load operation conditions. When the load is at the rated load, if the real-time speed is lower than 59% of the predetermined speed, the dual-motor joint drive mode will be automatically activated. The rated load refers to the standard load that the equipment can withstand for a long period of time during its design. For example, if the target speed is 1000 rpm, and it drops to 590 rpm, the main motor and the variable frequency motor will be triggered to work simultaneously, thereby enhancing power output and preventing the speed from continuing to drop, which would lead to production instability.

[0062] When the load decreases to no-load, if the real-time speed is lower than 64% of the predetermined speed, the dual-motor joint drive mode is activated ahead of schedule. This indicates that the system is more sensitive to speed drops under light load conditions. No-load refers to a state with almost no external resistance; for example, the motor requires almost no additional torque when idling. Therefore, the trigger point is raised to 64%, meaning that the dual-motor mode will be activated ahead of schedule as long as the speed is lower than the target speed of 640 rpm. Fluctuations in the motor itself during no-load operation can have a significant impact, necessitating the coordination of the dual motors to ensure stability.

[0063] Furthermore, this application also includes: when the real-time speed drops below 78% of the predetermined speed, the variable frequency motor switches to forward rotation mode; when the real-time speed is higher than 78% of the predetermined speed, the variable frequency motor switches to reverse rotation mode; wherein, the compensation amount is dynamically optimized based on the torque-speed square relationship of the quadratic load analyzed by the linguistic variables of the PID controller.

[0064] Specifically, when the real-time speed drops below 78% of the predetermined speed, the variable frequency motor switches to forward rotation mode. When the actual speed of the motor is significantly lower than the target speed, the variable frequency motor begins to provide additional power in the normal rotation direction to compensate for the insufficient speed. Real-time speed refers to the speed measured in real time during motor operation. The predetermined speed is a target value set according to task or process requirements. Forward rotation mode means that the motor outputs torque in the normal working direction. For example, if the target speed is 1000 rpm, when the actual speed drops below 780 rpm, the variable frequency motor will actively increase its power to push the speed back up.

[0065] When the real-time speed is higher than 78% of the preset speed, the variable frequency motor switches to reverse mode. This means that when the actual speed rises and exceeds the set threshold, the variable frequency motor counteracts the excessive speed by acting in reverse, thereby preventing the system from overshooting. In reverse mode, the variable frequency motor outputs control torque in the opposite direction to brake and stabilize the speed. For example, when the speed rises to more than 800 rpm, the variable frequency motor will adjust in reverse to make the speed approach the target value.

[0066] Specifically, the torque-sqrtual relationship of the quadratic load is analyzed based on the linguistic variables of the PID controller, and the compensation amount is dynamically optimized. That is, the load characteristics are analyzed by combining fuzzy control with PID parameters. Linguistic variables are quantities represented by fuzzy logic, such as speed deviation and deviation change rate. Through linguistic variables, the dynamic demand of the load can be understood. Quadratic load refers to fan or pump loads, where torque is proportional to the square of speed. If the speed doubles, the torque demand increases fourfold. Therefore, the compensation amount is dynamically optimized when the speed changes, which avoids insufficient compensation that causes the speed to drop too quickly, and also prevents overcompensation that causes fluctuations.

[0067] In summary, the method for adjusting the speed of a variable frequency drive motor by the controller provided in this application has the following technical effects: by achieving the technical goals of rapid motor response, precise speed regulation, and efficient energy distribution under different load conditions, it achieves the technical effects of improving system stability, reducing energy consumption, extending equipment service life, and optimizing production efficiency.

[0068] Example 2: Based on the same inventive concept as the method for adjusting the speed of a variable frequency drive motor by a controller in the foregoing examples, this application also provides a system for adjusting the speed of a variable frequency drive motor by a controller. Please refer to the appendix. Figure 2The system includes: a planetary gear train coupling structure construction module 1, used to construct a planetary gear train coupling structure based on the dual-motor power of the frequency converter; a real-time operation data acquisition module 2, used to establish a two-wire communication connection using the ModBus communication protocol and dynamically acquire the real-time operation data of the frequency converter; a real-time speed regulation decision acquisition module 3, used to dynamically analyze the real-time operation data through a PID controller and obtain a real-time speed regulation decision in combination with a predetermined load response strategy; and a speed regulation control module 4, used to perform speed regulation control on the planetary gear train coupling structure according to the real-time speed regulation decision.

[0069] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used for: the main motor is connected to the internal gear ring of the planetary gear train through a first reduction gear, and the variable frequency motor is connected to the sun gear of the planetary gear train through a second reduction gear, forming the planetary gear train coupling structure; wherein, the planet carrier of the planetary gear train serves as the output end to synthesize the dual motor speed of the dual motor power.

[0070] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used in the following ways: the main motor is a three-phase asynchronous motor that operates at its rated speed, and the variable frequency motor is a permanent magnet synchronous motor whose speed is adjusted by the frequency converter; wherein the power ratio of the main motor to the variable frequency motor is (1.5~2.5):1.

[0071] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used to: locate abnormal noise points in the real-time operating data that exceed the baseline equilibrium point; filter the abnormal noise points based on low-pass filtering to obtain a reconstructed operating waveform, and use the reconstructed operating waveform as input information for the PID controller; wherein, the abnormal noise points include amplitude abnormal noise points and frequency abnormal noise points.

[0072] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used to: obtain real-time key features based on the reconstructed operating waveform, and input the real-time key features to the PID controller to obtain the real-time speed regulation decision; wherein, the real-time key features include at least the stator winding current fluctuation mode, the rotor copper loss transient value, and the core loss steady-state value.

[0073] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used for: obtaining the real-time rotational speed based on the real-time key features, and comparing the real-time rotational speed with a predetermined rotational speed to obtain the real-time rotational speed deviation; performing time-series analysis on the real-time rotational speed deviation to obtain the deviation change rate, and forming a linguistic variable with the real-time rotational speed deviation; matching the target parameter combination corresponding to the linguistic variable in the fuzzy control rule base, and determining the real-time speed regulation decision based on the target parameter combination; wherein, when the load changes abruptly, the integral parameter is automatically strengthened to suppress speed overshoot.

[0074] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used for: the predetermined load response strategy refers to switching to dual-motor joint drive when the real-time speed is lower than 50%-60% of the predetermined speed for constant torque load, and enabling the variable frequency motor to compensate for speed when the real-time speed is lower than 65%-75% of the predetermined speed for quadratic load.

[0075] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used to: automatically start the dual-motor joint drive mode when the load is at the rated load and the real-time speed is lower than 59% of the predetermined speed; and start the dual-motor joint drive mode in advance when the load is reduced to no load and the real-time speed is lower than 64% of the predetermined speed.

[0076] Furthermore, the system for adjusting the speed of the variable frequency drive motor by the controller is also used to: switch the variable frequency motor to forward rotation mode when the real-time speed drops below 78% of the predetermined speed; and switch the variable frequency motor to reverse rotation mode when the real-time speed is higher than 78% of the predetermined speed; wherein, the compensation amount is dynamically optimized based on the torque-speed square relationship of the quadratic load analyzed by the linguistic variables of the PID controller.

[0077] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on the differences from other embodiments. The method and specific examples of the controller adjusting the speed of the variable frequency drive motor in the foregoing embodiment 1 are also applicable to the system of the controller adjusting the speed of the variable frequency drive motor in this embodiment. Through the foregoing detailed description of the method of the controller adjusting the speed of the variable frequency drive motor, those skilled in the art can clearly understand the system of the controller adjusting the speed of the variable frequency drive motor in this embodiment. Therefore, for the sake of brevity, it will not be described in detail here.

[0078] The above description of the disclosed embodiments enables those skilled in the art to make or use this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0079] Obviously, those skilled in the art can make various modifications and variations to this application without departing from the spirit and scope of this application. Therefore, if such modifications and variations fall within the scope of this application and its equivalents, this application also intends to include such modifications and variations.

Claims

1. A method for adjusting the speed of a variable frequency drive motor using a controller, characterized in that, include: A planetary gear train coupling structure is constructed based on a dual-motor power system using a frequency converter; A two-wire communication connection is established using the ModBus communication protocol, and the real-time operating data of the frequency converter is dynamically acquired. The real-time operating data is dynamically analyzed by a PID controller, and a real-time speed regulation decision is obtained by combining it with a predetermined load response strategy. Speed ​​control is performed on the planetary gear train coupling structure based on the real-time speed control decision.

2. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 1, characterized in that, The dual-motor power system includes a main motor and a variable frequency motor. Based on the variable frequency drive, the dual-motor power system constructs a planetary gear train coupling structure, including: The main motor is connected to the internal gear ring of the planetary gear train through a first reduction gear, and the variable frequency motor is connected to the sun gear of the planetary gear train through a second reduction gear, forming the planetary gear train coupling structure; The planet carrier of the planetary gear train serves as the output end to synthesize the dual-motor speed of the dual-motor power.

3. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 2, characterized in that, The main motor is a three-phase asynchronous motor that operates at its rated speed, and the variable frequency motor is a permanent magnet synchronous motor whose speed is adjusted by the frequency converter. The power ratio of the main motor to the variable frequency motor is (1.5~2.5):

1.

4. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 1, characterized in that, After establishing a two-wire communication connection using the ModBus communication protocol and dynamically acquiring the real-time operating data of the frequency converter, the process also includes: Locate abnormal noise points in the real-time running data that exceed the baseline equilibrium point; The abnormal noise is filtered by low-pass filtering to obtain the reconstructed operating waveform, and the reconstructed operating waveform is used as the input information of the PID controller. The abnormal noise includes amplitude abnormal noise and frequency abnormal noise.

5. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 4, characterized in that, The abnormal noise is filtered using a low-pass filter to obtain a reconstructed operating waveform, which is then used as input information for the PID controller, including: The real-time key features are obtained based on the reconstructed operating waveform, and the real-time key features are input to the PID controller to obtain the real-time speed regulation decision; The real-time key features include at least the stator winding current fluctuation mode, the transient value of rotor copper loss, and the steady-state value of core loss.

6. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 5, characterized in that, The PID controller has an embedded fuzzy control rule base. Based on the reconstructed operating waveform, real-time key features are obtained and input into the PID controller to obtain the real-time speed regulation decision, including: The real-time rotational speed is obtained based on the aforementioned key real-time features, and the real-time rotational speed is compared with the predetermined rotational speed to obtain the real-time rotational speed deviation; The deviation rate of change is obtained by performing time-series analysis on the real-time speed deviation, and is combined with the real-time speed deviation to form a linguistic variable. The target parameter combination corresponding to the linguistic variable is matched in the fuzzy control rule base, and the real-time speed regulation decision is determined based on the target parameter combination; Among them, when the load changes abruptly, the integral parameter is automatically enhanced to suppress speed overshoot.

7. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 6, characterized in that, The predetermined load response strategy refers to switching to dual-motor joint drive when the real-time speed is lower than 50%-60% of the predetermined speed for constant torque loads, and activating the variable frequency motor to compensate for speed when the real-time speed is lower than 65%-75% of the predetermined speed for quadratic loads.

8. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 7, characterized in that, For constant torque loads, when the real-time speed is lower than 50%-60% of the predetermined speed, the system switches to dual-motor joint drive, including: When the load is at the rated load, if the real-time speed is lower than 59% of the predetermined speed, the dual-motor joint drive mode will be automatically started. When the load is reduced to no load, if the real-time speed is lower than 64% of the predetermined speed, the dual-motor joint drive mode is started in advance.

9. The method for adjusting the speed of a variable frequency drive motor by a controller as described in claim 7, characterized in that, For quadratic loads, when the real-time speed is lower than 65%-75% of the predetermined speed, the variable frequency motor is activated to compensate for the speed, including: When the real-time speed drops below 78% of the predetermined speed, the variable frequency motor switches to forward rotation mode; When the real-time speed is higher than 78% of the predetermined speed, the variable frequency motor switches to reverse mode; Specifically, the torque-speed square relationship of the quadratic load is analyzed based on the linguistic variables of the PID controller, and the compensation amount is dynamically optimized.

10. A system for regulating the speed of a variable frequency drive motor by a controller, characterized in that, The steps for implementing the method of adjusting the speed of a variable frequency drive motor by a controller according to any one of claims 1 to 9 include: A planetary gear train coupling structure construction module is used to construct a planetary gear train coupling structure based on a dual-motor power system of a frequency converter. The real-time operating data acquisition module is used to establish a two-wire communication connection using the ModBus communication protocol and dynamically acquire the real-time operating data of the frequency converter; The real-time speed regulation decision-making module is used to dynamically analyze the real-time operating data through the PID controller and obtain a real-time speed regulation decision in combination with a predetermined load response strategy. The speed control module is used to perform speed control on the planetary gear train coupling structure based on the real-time speed control decision.

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