Intelligent electric valve actuator and control method and device thereof

Abstract

The application discloses an intelligent electric valve actuator and a control method and device thereof. The intelligent electric valve actuator comprises an intelligent electric valve control device, and high-precision control of valve opening and closing is realized by adopting an intelligent electric valve control method. The control method comprises the following steps: when the valve is opened or closed, a first control mode is used to run at a high speed from a starting point to a stroke limit switching point and is switched to a second control mode; the first control mode is a valve position estimation mode based on speed value integration; the second control mode is used to run at a low speed to a valve contact point; the second control mode is a torque threshold positioning control mode; and the second control mode is continuously run until torque reaches a stable value and is maintained for a set time, which is a stopping point; the valve opening or closing operation is stopped at the stopping point; the current position is reset as an actual valve opening or closing position; and valve plate position errors accumulated in the first control mode are cleared, so that position self-calibration is completed.

Description

Technical Field

[0001] This invention relates to valve drive and control technology, and in particular to an intelligent electric valve actuator based on a three-phase AC asynchronous motor without position or torque sensors, and its control method and device. Background Technology

[0002] A typical structure of existing electric valve actuators is shown in Figure 1. All of them require physical sensors (such as valve position sensors and torque sensors) to provide valve position feedback. Valve position sensors are divided into point-to-point types (e.g., reed switches, limit switches, magnetic switches) and continuous types (e.g., potentiometers, encoders, rotary transformers, etc.). Torque sensors are also divided into various types based on their measurement principles and installation methods. In practical applications, these sensors and their auxiliary systems mainly suffer from the following problems:

[0003] 1) Poor environmental adaptability: Under environments such as high temperature, high humidity, high pressure, salt spray, vibration, radiation or electromagnetic interference, the sensor (especially the integrated circuit inside the sensor) is prone to aging; condensation or dust may cause short circuits in the sensor; electromagnetic noise may cause sensor signal distortion or feedback errors, and the above sensor failures can easily lead to position feedback errors, causing valve malfunctions or even impact damage, seriously threatening valve safety;

[0004] 2) Poor reliability. For example, point-type sensors contain mechanical moving parts, which are prone to wear, poor contact, and contact adhesion; continuous sensors have complex structures and have problems such as loosening, wire breakage, and short lifespan. The above sensor failures can easily lead to position feedback errors, causing valve malfunctions or even impact damage, seriously threatening the safety of the pipeline system.

[0005] 3) Frequent maintenance: Sensors are consumable parts and require regular on-site calibration or replacement, which increases the workload, maintenance and management costs.

[0006] 4) Installation and debugging are complex. Point-type sensors need to be mechanically linked to the valve stem and require precise alignment, making installation and debugging difficult. Continuous sensors have high circuit requirements and complex interface circuits.

[0007] 5) Increased costs: Valve position sensors (especially continuous high-precision valve position sensors), torque sensors and a series of related components such as cables, connectors, signal modulation circuits, industrial bus interfaces, positioning and triggering mechanisms, and sensor packaging will significantly increase system costs and integration difficulty; if they need to be adapted to nuclear irradiation environments, the cost of their sensors and accessories will be even more expensive. Summary of the Invention

[0008] The technical problem to be solved by the present invention is to address the above-mentioned deficiencies of the prior art by providing a sensorless intelligent electric valve actuator based on a three-phase AC asynchronous motor and its control method and device.

[0009] To achieve the above objectives, the present invention provides an intelligent electric valve control method, comprising the following steps:

[0010] S100, when opening / closing the valve, the valve runs at high speed from the starting point in the first control mode to the stroke limit switching point and then switches to the second control mode. The first control mode is a valve position estimation mode based on speed numerical integration. First, the motor speed is converted into the valve plate speed, and then the real-time position of the valve plate is obtained according to the valve plate speed integration.

[0011] S200: Run at low speed to the valve contact point in the second control mode. The second control mode is a torque threshold positioning control mode, which determines the contact position by monitoring changes in motor torque, accurately locating the valve opening / closing contact point and the stop point. The valve contact point is reached when the torque reaches the set threshold.

[0012] S300. Continue to operate in the second control mode until the torque reaches a stable value, and stop at the set time. Stop the opening / closing of the valve at the stop point, reset the current position to the actual opening / closing position of the valve, and clear the valve plate position error accumulated in the first control mode to complete the position self-calibration.

[0013] The starting point and the stopping point are the endpoint and the starting point of each other. The starting point position is the previous stopping point position or is obtained through one-click debugging search. An open / close valve closed loop is formed between the starting point and the stopping point, and steps S100-S300 are repeated.

[0014] In the above-mentioned intelligent electric valve control method, the stroke limit switching point includes a first speed change trigger point, at which the set target speed and torque limit are switched, and the system continues to operate in the first control mode.

[0015] In the above-mentioned intelligent electric valve control method, when the valve is opened, the first speed change trigger point corresponds to the acceleration start point after the end of the low-speed operation phase of the waterproof hammer; when the valve is closed, the first speed change trigger point corresponds to the deceleration start point at the beginning of the low-speed operation phase of the waterproof hammer.

[0016] The above-mentioned intelligent electric valve control method further includes a second speed change trigger point at the stroke limit switching point. At the second speed change trigger point, the system switches to the second control mode and reduces the operating speed to a set ratio of the maximum speed (preferably 10%–30%) to ensure safe and stable identification of the valve contact point.

[0017] The above-mentioned intelligent electric valve control method, wherein the first control mode includes:

[0018] The system modeling steps include establishing a mathematical and physical model of a three-phase AC asynchronous motor used to drive the valve, and using coordinate transformation to reduce the order and decouple the mathematical and physical model of the three-phase AC asynchronous motor.

[0019] The speed estimation step involves obtaining the real-time speed of the three-phase AC asynchronous motor based on the mathematical and physical model; and

[0020] The position is determined by the velocity integration step, which uses the real-time rotational speed obtained from the velocity estimation step to perform velocity integration calculations using a fixed sampling period, thereby obtaining the current position of the valve.

[0021] The aforementioned intelligent electric valve control method also includes a calibration and compensation step for the valve position integral error. Calibration is performed using a two-dimensional grid sampling method, and compensation is performed using a bilinear interpolation method to control the position error within the allowable range.

[0022] The aforementioned intelligent electric valve control method also includes a one-click debugging step, used for position initialization and stroke calibration after the valve actuator is first installed, after important parameters are modified, or when position information is lost due to accidental power failure. The second control mode is used to automatically search for the valve plate's opening dead point, the contact point between the valve plate and the valve seat, and the valve plate's full stroke displacement value between the valve plate's opening dead point and the contact point between the valve plate and the valve seat.

[0023] The aforementioned intelligent electric valve control method, wherein the one-button debugging step includes:

[0024] The valve moves slowly along the valve opening direction in the second control mode with low speed and low torque, and the torque change is monitored in real time to identify the valve opening dead point.

[0025] After identifying the valve opening dead point, the operating direction is switched, and the valve continues to move slowly along the valve closing direction in a low-speed, low-torque second control mode, while real-time monitoring of torque changes to identify the valve-seat contact point; and

[0026] The relative movement distance of the valve plate is recorded synchronously using the first control mode in order to calculate the full stroke displacement value of the valve plate from the valve plate's opening dead point to the contact point between the valve plate and the valve seat.

[0027] To better achieve the above objectives, the present invention also provides an intelligent electric valve control device, wherein the intelligent electric valve control method described above is used.

[0028] To better achieve the above objectives, the present invention also provides an intelligent electric valve actuator, wherein the above-described intelligent electric valve control method is used to achieve high-precision control of valve opening and closing.

[0029] The technical advantages of this invention are as follows:

[0030] This invention eliminates the need for valve position and torque sensors. By combining a second control mode with a first control mode, it achieves high-precision control of the valve opening and closing process without any physical valve position or torque sensor feedback. Compared to existing sensor-dependent control methods, this invention is more reliable and efficient, capable of efficiently and accurately completing valve opening / closing operations under various operating conditions. It is particularly suitable for electric valve control in extremely harsh environments, solving a series of problems faced by existing valve actuators that rely on position sensors, including poor environmental adaptability, low reliability, frequent maintenance, limited functionality, complex installation and debugging, and high cost. Throughout operation, it can smoothly switch between the first and second control modes, effectively identifying and acquiring the valve's contact and stop points, thereby ensuring the continuity and stability of the execution action. Even without using valve position and torque sensors, it can still achieve positioning and control effects comparable to existing sensor control.

[0031] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the present invention. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structure of an existing electric valve actuator;

[0033] Figure 2 This is a schematic diagram of the structure of an intelligent electric valve actuator according to an embodiment of the present invention;

[0034] Figure 3 This is a schematic diagram of the working principle of an on / off valve according to an embodiment of the present invention;

[0035] Figure 4 This is a monitoring curve of the valve opening process according to an embodiment of the present invention;

[0036] Figure 5 This is a monitoring curve of the valve closing process according to an embodiment of the present invention;

[0037] Figure 6 This is a schematic diagram illustrating the working principle of one-click debugging according to an embodiment of the present invention.

[0038] Among them, the attached figures are labeled

[0039] 1. Starting point

[0040] 2. Contact points

[0041] 3 Stop Point

[0042] 4 First gear shift trigger point

[0043] 5 Second speed change trigger point Detailed Implementation

[0044] The structural and working principles of the present invention will be described in detail below with reference to the accompanying drawings:

[0045] To make the objectives, technical solutions, and advantages of this invention clearer, the embodiments of this invention will be further described in detail below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of this invention and are not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

[0046] See Figure 2 Figure 2 is a schematic diagram of the structure of an intelligent electric valve actuator according to an embodiment of the present invention. The intelligent electric valve actuator of the present invention includes an intelligent electric valve control device, a three-phase AC asynchronous motor, and a transmission device. The intelligent electric valve control device is connected to both a three-phase power supply and the three-phase AC asynchronous motor. The three-phase AC asynchronous motor is connected to the transmission device, and the transmission device is connected to the valve. It may also include a handwheel, which can be connected to either the three-phase AC asynchronous motor or the transmission device. The handwheel serves as a manual emergency / maintenance operation interface, independent of the intelligent automatic control method, and is used for mechanical positioning and release from jamming during power failure or maintenance. The intelligent electric valve control device has logic control and variable frequency vector drive control functions. It is connected to the three-phase AC asynchronous motor via a three-phase AC cable to drive and control the three-phase AC asynchronous motor. The output shaft of the three-phase AC asynchronous motor is connected to the input shaft of the transmission device. The output shaft of the transmission device is ultimately connected to the input shaft of the valve. The handwheel can be connected to the three-phase AC asynchronous motor or the transmission device via a quick-connect device when needed, or it can be fixedly connected to the three-phase asynchronous motor or the transmission device.

[0047] This intelligent electric valve actuator eliminates the need for physical valve position and torque sensors; its structure contains no valve position or torque sensors. It uses a method calculating the valve's operating position using internal parameters of a variable frequency vector drive controller, offering significant advantages in reliability, maintainability, environmental adaptability, and system cost. The actuator comprises four functional modules: an intelligent valve drive controller, a three-phase AC asynchronous motor, a transmission device, and a handwheel. It employs a built-in intelligent electric valve control method to achieve high-precision valve opening and closing, exhibiting significant structural simplification and advantages. This intelligent valve actuator is an intelligent valve variable frequency vector actuator. Based on the three-phase voltage and current vector values ​​output to the three-phase AC asynchronous motor, it calculates the valve running speed. Based on the integral result of the running speed, it obtains the valve's relative displacement. Based on the starting point of the speed integral plus the valve's relative displacement, it calculates the position of the next valve critical point. Based on the calibration and compensation method of the valve critical point position estimation error, it reduces the valve position estimation error. Based on the calculated valve critical point position, it replaces the position sensor to obtain the valve critical point position, and then controls the valve operation. Based on the upper limit of the valve position estimation error, it determines the low-speed search distance and uses the intelligent valve variable frequency vector actuator to control the valve to run at low speed in torque limiting mode to search for the limit position. After finding the limit position, it initializes the current position and resets the accumulated position error during the operation to zero.

[0048] The intelligent electric valve control device of this invention is used to implement an intelligent electric valve control method. Based on the control method of an intelligent electric valve actuator without position or torque sensors, five key position points are set during the typical opening / closing control process of the valve actuator. Through dynamic switching between a first control mode and a second control mode, high-precision valve opening / closing control is achieved under conditions without position or torque sensors. These key position points, also known as function switching points, include starting point 1, first speed change trigger point 4, second speed change trigger point 5, contact point 2, and stop point 3. Starting point 1 is the initial position of the intelligent valve frequency converter vector drive, typically the fully open / fully closed valve position or the closed valve position, requiring high positional accuracy. This position is obtained through one-key debugging search or by reverse calculation from the stop point 3 of the previous reverse operation. The intelligent valve variable frequency vector drive controller starts at starting point 1 and enters the first control mode. Overcoming static friction and system inertia, it reaches the set speed and then runs at a constant speed. The first speed change trigger point 4 is the first speed switching point. This trigger point is designed to prevent sudden changes in pipeline pressure / flow and to avoid phenomena such as water hammer / cavitation. It has low position accuracy requirements; ±5% position accuracy is sufficient. For example, in the water hammer mode, when the valve is open, this position corresponds to the acceleration start point 1 after the low-speed operation phase of the water hammer ends; when the valve is closed, this position corresponds to the deceleration start point 1 at the beginning of the low-speed operation phase of the water hammer. The intelligent valve variable frequency vector drive controller sets a new target speed and torque limit at the first speed change trigger point 4, and then... The system continues to operate in the first control mode. The second speed-changing trigger point 5 is the starting point 1 for the second mode switch. At this position, the intelligent valve frequency converter vector drive switches to the second control mode, reducing the speed to 10%–30% of the maximum speed to ensure safe and stable identification of the valve contact point 2. The second speed-changing trigger point 5 is a speed-changing trigger point set to improve efficiency or reduce impact. Its order with the first speed-changing trigger point 4 can be interchanged. It has low position accuracy requirements; ±5% position accuracy is sufficient. Contact point 2 is the point where the valve plate and valve seat make physical contact. For example, during valve closing, the valve is basically closed but not yet fully sealed; during valve opening, the valve is fully open. From this point onward, the actuator switches from position control to torque control, which requires high position accuracy. Most existing actuators do not have torque control capabilities, and their execution logic does not include contact point 2. The intelligent valve frequency converter vector drive determines contact point 2 based on the continuous increase in torque, triggering the torque control logic to ensure positioning accuracy. After recognizing contact point 2, the intelligent valve variable frequency vector drive continues to operate in the second control mode. Stop point 3 is the final position of the intelligent valve variable frequency vector drive after completing the valve opening or closing action, typically the fully open / fully closed position of the valve, requiring high accuracy in position and torque. The drive maintains the target torque until a stable state in the second control mode, and then stops outputting after a certain period.This position point is recorded as stop point 3, simultaneously clearing any accumulated position errors that may have arisen from the first control mode, and serving as the basis for deriving the starting point 1 for the next action, thus forming a closed loop in the valve switching process. Other points may also be included, such as a pre-pressure point for "soft shut-off" of high-pressure valves to prevent seal damage; and a retraction point for safe retraction to check the sealing degree, prevent jamming, and avoid seal damage. These other points are not standard requirements and can be obtained through simple modifications of the typical process described above.

[0049] Most existing valve actuators rely on position sensors to obtain all five key points mentioned above. Some actuators obtain the first three points using position sensors and the last two points using torque sensors. The starting point 1, contact point 2, and stop point 3 are used to achieve precise control of the valve actuator throughout its entire stroke, while the first speed change trigger point 4 and the second speed change trigger point 5 are used to further implement various optimized control strategies. This invention enables full-stroke position control without any position or torque sensors. It accurately identifies and controls the five key position points mentioned above without relying on any position sensors, thereby realizing the complete opening / closing control process of the valve actuator. In this embodiment, the starting point 1 is derived by reversing the position of the stopping point 3 of the previous action and serves as the starting reference point for the current action; the speed change trigger point is calculated through the first control mode, that is, the speed is estimated by integral based on the actuator operating parameters (such as the number of steps, current, and time), and corrected by calibration data to achieve position estimation accuracy control; the contact point 2 and the stopping point 3 are identified through the second control mode, that is, when approaching the target position, the actuator enters the torque exploration state, and the positions of the contact point 2 and the stopping point 3 are identified by the torque change to achieve high-precision positioning.

[0050] See Figure 3 , Figure 3 This is a schematic diagram illustrating the working principle of an on / off valve according to an embodiment of the present invention. The intelligent electric valve control method of the present invention prioritizes the use of a first control mode during valve opening and closing to achieve efficient operation. When the accuracy of the first control mode is insufficient and accumulated errors may cause collisions between the valve plate and valve seat, it switches to a second control mode. In this invention, the position estimation accuracy of the first control mode is ±2%, and after adding a 4-fold safety margin, the stroke of the second control mode is set to 10% of the total stroke. That is, during the valve opening process, the actuator operates in the first control mode until the opening degree reaches 90%, and then switches to the second control mode; at the end of the stroke, when it is necessary to accurately obtain the position point where the valve plate and valve seat physically contact each other and clear the accumulated position error generated by the first control mode, it switches to the second control mode.

[0051] The intelligent electric valve control method of this embodiment includes the following steps:

[0052] In step S100, when opening / closing the valve, the valve runs at high speed from the starting point 1 in the first control mode to the stroke limit switching point and then switches to the second control mode. The first control mode is a valve position estimation mode based on speed numerical integration. First, the motor speed is converted into the valve plate speed, and then the real-time position of the valve plate is obtained according to the valve plate speed integration. The starting point 1 is usually the valve fully open / fully closed position, which requires high position accuracy.

[0053] Step S200: Run at low speed in the second control mode to valve contact point 2. The second control mode is a torque threshold positioning control mode. The contact position is determined by monitoring the change in motor torque, and the valve opening / closing contact point 2 and the stop point 3 are accurately located. Valve contact point 2 is reached when the torque reaches the set threshold.

[0054] Step S300: Continue to run the second control mode until the torque reaches a stable value, and stop at the set time point 3. Stop the opening / closing of the valve at the stop point 3, reset the current position to the actual opening / closing position of the valve, and clear the valve plate position error accumulated in the first control mode to complete the position self-calibration.

[0055] In this method, the starting point 1 and the stopping point 3 are each other's starting and ending points. The current starting point 1 is the previous stopping point 3 or is obtained through a one-click debugging search. An open / close valve closed loop is formed between the starting point 1 and the stopping point 3, and steps S100-S300 are repeated. That is, the starting point 1 and the stopping point 3 are each other's starting and ending points; the previous stopping point 3 is the current starting point 1. This control method forms a closed loop between the starting point 1 and the stopping point 3 and repeats the cycle.

[0056] The first control mode conversion utilizes the transmission ratio parameters of the transmission device (such as gear ratio, lead screw pitch, etc.) and speed numerical integration calculations. First, the motor speed is converted into valve plate speed through the transmission ratio. Then, the valve plate speed is integrated to obtain the valve plate position, achieving position estimation accuracy within ±2%, meeting the ±5% accuracy requirement for variable speed trigger point control. To eliminate the cumulative position error generated during high-speed operation in the first control mode and ensure the accuracy of valve opening / closing positions, a second control mode, namely the position torque exploration method, is introduced at the end of the valve opening / closing stroke. Existing three-phase AC asynchronous motor drive control technology has achieved precise speed and torque control and can smoothly switch between the two. In particular, torque control based on vector control technology can achieve high-precision adjustment of the motor output torque, with stable output torque within the range from zero speed to maximum speed, providing a technical foundation for the second control mode of valve opening / closing positions. The second control mode can achieve absolute position identification of contact point 2 and stop point 3 and can eliminate the cumulative error generated by the first control mode, ensuring that the control accuracy of contact point 2 and stop point 3 meets the sealing and control requirements. Meanwhile, the stop point 3 identified by the torque in the second control mode can be used as the starting point 1 for the next action, forming a complete closed-loop control.

[0057] After initial approach in the first control mode, the actuator switches to the second control mode, continuing to advance at a certain speed while continuously monitoring the feedback torque. As the valve plate contacts the valve seat, the load torque increases significantly. When the detected torque reaches the set threshold upper limit, the actuator maintains the torque for a certain period until it stabilizes, then stops outputting and resets the current position to the actual open / closed position of the valve, completing the position self-calibration process and eliminating accumulated errors. The second control mode can accurately identify the contact point 2 between the valve plate and the valve seat, effectively correcting the position error caused by the first control mode, achieving closed-loop position control of the valve opening / closing process without a valve position sensor or torque sensor. By combining the first and second control modes, the actuator achieves high-precision end-effector positioning under conditions without a position sensor or torque sensor.

[0058] In this embodiment, the first control mode includes:

[0059] The system modeling steps include establishing a mathematical and physical model of a three-phase AC asynchronous motor used to drive the valve, and using coordinate transformation to reduce the order and decouple the mathematical and physical model of the three-phase AC asynchronous motor.

[0060] The speed estimation step involves obtaining the real-time speed of the three-phase AC asynchronous motor based on the mathematical and physical model; and

[0061] The position is determined by the velocity integration step, which uses the real-time rotational speed obtained from the velocity estimation step to perform velocity integration calculations using a fixed sampling period, thereby obtaining the current position of the valve.

[0062] It may also include calibration and compensation steps for valve position integral error, using a two-dimensional grid sampling method for calibration and a bilinear interpolation method for compensation, so as to control the position error within the allowable range.

[0063] In this embodiment, a first control mode is used for high-speed operation during the initial stage of valve opening / closing to ensure operational efficiency. The actuator output torque is also continuously monitored in the first control mode to avoid problems such as jamming. When approaching the stroke limit, the system switches to a second control mode, operating at low speed and using torque to explore the stop point 3 to correct the position error introduced by the first control mode, ensuring position accuracy. The combination of these two modes achieves precise position control even without position or torque sensors. Because the position error in the first control mode needs to be compensated for by the second control mode, the position estimation accuracy of the first control mode directly affects the execution stroke of the second control mode, thus affecting the actuator's valve opening / closing efficiency. Therefore, this embodiment may include steps to improve the position estimation accuracy of the first control mode.

[0064] During valve opening / closing, the position estimation accuracy in the first control mode is crucial, as it directly determines the required stroke in the second control mode, thus affecting the overall efficiency of the actuator. Based on practical experience, to ensure estimation accuracy, the execution speed in the second control mode typically does not exceed 30% of the actuator's maximum speed. Therefore, the second control mode reduces valve opening / closing efficiency and increases the required time. The specific increase in valve opening / closing time can be calculated using the following formula:

[0065] ;

[0066] ;

[0067] in, Valve opening / closing stroke, in meters (m); The error caused by using the position estimation mode throughout the entire process is expressed in meters (m). The execution time for using the location estimation mode throughout the process, in seconds; The change in execution time after the second control mode is adopted in the final stage, expressed in seconds; The maximum execution speed of the actuator is expressed in m / s. The execution speed of the second control mode is expressed in m / s.

[0068] Based on the above calculations:

[0069] if ,but ;

[0070] if ,but ;

[0071] It is evident that for every 10% increase in position estimation error, the valve opening / closing execution time increases by 23.3%; when the position error reaches 40%, the execution time almost doubles.

[0072] The position estimation error within ±5% will not have a significant impact on the valve's execution efficiency. The position accuracy requirement of the aforementioned speed change trigger point is also ±5%. Therefore, this invention sets the position estimation error within the range of -5% to 5%.

[0073] See Figure 4 and Figure 5 , Figure 4 This is a monitoring curve of the valve opening process according to an embodiment of the present invention. Figure 5 This is a monitoring curve of the valve closing process according to an embodiment of the present invention. The speed change point is a speed switching point set during the valve stroke to meet process requirements, such as preventing water hammer, soft shut-off, and reducing impact. It can be set based on stroke ratio, absolute / relative distance, or absolute / relative distance. For example, in preventing water hammer, it can be set based on stroke ratio. During valve opening, the 20% position of the valve plate opening can be set as the first speed change trigger point 4. When the valve plate opening is less than 20%, the actuator operates at a lower speed (usually within 30% of the maximum speed) to reduce the rate of change of pressure difference across the valve plate and slowly release fluid kinetic energy. When the valve plate opening reaches 20%, an acceleration command is triggered, increasing the speed to more than 50% of the maximum speed to improve valve opening efficiency. During valve closing, it can... The first speed change trigger point 4 for valve closing is set at 20% of the valve plate opening. As the valve plate opening gradually decreases from 100% to 20%, the actuator maintains a relatively high speed (usually more than 50% of the maximum speed) to improve valve closing efficiency. When the valve plate opening drops to 20%, deceleration control is triggered, reducing the execution speed to within 30% of the maximum speed, allowing the valve plate to move at a low speed in the remaining stroke. This slows down the pressure difference change rate caused by the sudden drop in fluid velocity on both sides of the valve plate, preventing water hammer effect caused by instantaneous fluid cutoff. For soft shut-off or shock reduction, the speed change can also be set based on the stroke ratio. During valve closing, the second speed change trigger point 5 for valve closing can be set at 10% of the valve plate opening. When the valve plate opening decreases to 10%, the actuator triggers the speed change command again, reducing the speed to within 30% of the maximum speed and switching to the second control mode. This allows for precise searching of the contact point 2 between the valve plate and the valve seat at low speed, achieving soft shut-off, ensuring sealing reliability, and reducing mechanical shock.

[0074] Setting based on absolute / relative distance is similar to setting based on the forming ratio, except that the stroke ratio is converted into absolute / relative distance according to the specific stroke of the valve plate. The speed change trigger point can also be set according to the operating conditions and process parameters. For example, when the pipeline inertia is large and the fluid pressure difference is high, the first speed change trigger point 4 for opening the valve can be closer to the fully open position; when the system is not sensitive to the switching efficiency, the second speed change trigger point 5 for closing the valve can be further away from the fully closed position, and the exploration speed can be reduced to reduce mechanical shock.

[0075] In this embodiment, the travel limit switching point includes a first speed change trigger point 4. At the first speed change trigger point 4, the set target speed and torque limit are switched, and operation continues in the first control mode. The first speed change trigger point 4 is designed to prevent sudden changes in pipeline pressure / flow and avoid phenomena such as water hammer / cavitation. Its positional accuracy requirement is low; typically, ±5% positional accuracy is sufficient. In this embodiment, when the valve is open, the first speed change trigger point 4 corresponds to the acceleration start point 1 after the low-speed operation phase of water hammer is completed; when the valve is closed, the first speed change trigger point 4 corresponds to the deceleration start point 1 at the beginning of the low-speed operation phase of water hammer.

[0076] The travel limit switching point may also include a second speed change trigger point 5. At the second speed change trigger point 5, the system switches to the second control mode, reducing the operating speed to 10%–30% of the maximum speed to ensure safe and stable identification of the valve contact point 2. The second speed change trigger point 5 is a speed change trigger point set to improve efficiency or reduce impact. Its order with the first speed change trigger point 4 can be interchanged. Its positional accuracy requirement is low; typically, ±5% positional accuracy is sufficient.

[0077] Existing vector frequency converter technology for three-phase AC asynchronous motors can acquire the speed and torque of the three-phase AC asynchronous motor in real time, achieving precise speed and torque control and smooth switching between the two. Based on this, the intelligent valve frequency converter vector drive controller of this invention uses speed integration calculation to convert the real-time speed of the motor into the real-time position of the valve, and uses this real-time position to obtain the speed switching point during execution. This control mode, which obtains the position through speed estimation and speed integration, is the first control mode. The first control mode can obtain the valve position without a physical valve position sensor, but its accuracy is not as high as that of a valve position sensor, and it suffers from accumulated errors. Therefore, this invention applies torque control during the valve opening / closing process, detecting changes in motor torque to determine the contact position between the valve plate and the valve body, i.e., the end position of opening / closing the valve, thus eliminating dependence on valve position sensors and torque sensors. This working mode, which determines the contact position through changes in motor torque, accurately locates the end position of opening / closing the valve, and eliminates the accumulated position errors of the first control mode, is the second control mode.

[0078] The control method in this embodiment can be implemented using only the starting point 1, contact point 2, and stop point 3. The actuator can operate in the first control mode throughout the entire stroke, and directly switch to the second control mode at the end of the stroke to identify contact point 2 and stop point 3, thereby completing closed-loop control. In practical applications, only the first speed change trigger point 4 can be set. In this way, the actuator still operates in the first control mode for most of the stroke, and when the estimation accuracy near the end position is insufficient, it switches to the second control mode through the first speed change trigger point 4 to complete the precise end-positioning.

[0079] See Figure 6 , Figure 6 This is a schematic diagram illustrating the working principle of one-click debugging according to an embodiment of the present invention. To simplify the installation and debugging process and improve the ease of use and reliability of the system in practical applications, this embodiment may also include a one-click debugging step based on a second control mode. This step is used for position initialization and stroke calibration after the valve actuator is first installed, after important parameters are modified, or when position information is lost due to accidental power failure. The second control mode automatically searches for the valve plate's opening dead point, the contact point 2 between the valve plate and the valve seat, and the valve plate's full stroke displacement value between the valve plate's opening dead point and the contact point 2 between the valve plate and the valve seat.

[0080] One-click debugging is used to quickly and automatically establish critical position identification and control functions, improving deployment efficiency and reliability. Especially in complex field conditions where personnel cannot access the site, one-click debugging may be the only option. One-click debugging automatically calibrates and initializes critical mechanical limit positions, including the valve opening dead point, the valve plate and valve seat contact point 2, and the total displacement value between them. This provides accurate boundaries and reference strokes for subsequent position estimation in the first control mode and torque search in the second control mode. The valve opening dead point is the stopping point of the valve opening process and also the starting point of the valve closing process; the contact point between the valve plate and valve seat is the starting point of the valve opening process and approximately the stopping point of the valve closing process. In this embodiment, the one-click debugging steps include:

[0081] First, the valve is slowly moved along the valve opening direction in the second control mode with low speed and low torque, and the torque change is monitored in real time to identify the valve opening dead point.

[0082] After identifying the valve opening dead point, the operating direction is switched, and the valve continues to move slowly along the valve closing direction in a low-speed, low-torque second control mode, while real-time monitoring of torque changes to identify the valve-seat contact point; and

[0083] During the exploration of the valve and valve seat contact point, the relative movement distance of the valve plate is recorded simultaneously using the first control mode in order to calculate the full stroke displacement value of the valve plate from the valve plate's opening dead point to the contact point between the valve plate and the valve seat.

[0084] In one embodiment of the present invention, after the intelligent electric valve actuator is installed, a one-key debugging process is first required to obtain the valve closing contact point, valve opening dead point, and valve plate full stroke displacement values. After the one-key debugging is completed, valve opening / closing operations can be performed. A typical valve closing execution process is as follows: Figure 6 As shown, when the valve is closed, the intelligent electric valve actuator runs from the starting point 1 in the first control mode to the variable speed trigger point, then switches to the second control mode and runs at low speed to the contact point 2. Finally, after the torque stabilizes and is maintained for a set time, such as 3 seconds, the output stops and the position error is cleared, and the valve closing process ends. The specific implementation methods of one-button debugging, the first control mode, and the second control mode in this embodiment are as follows:

[0085] One-click debugging: Upon receiving the one-click debugging command, the actuator first moves slowly along the valve opening direction in a low-speed, low-torque second control mode, while monitoring torque changes in real time to identify the valve opening dead point. The torque exploration speed is typically set to 10% to 30% of the actuator's maximum speed, and the torque limit is set to 30% to 80% of the actuator's rated torque. After identifying the valve opening dead point, the operating direction is switched, and the actuator continues to move slowly along the valve closing direction in a low-speed, low-torque second control mode with corresponding parameters, while monitoring torque changes in real time to identify the valve-seat contact point 2. During the contact process, the actuator torque continuously increases and tends to stabilize until it approaches the preset torque control threshold, thereby confirming the position of contact point 2. During the exploration of the valve-seat contact point 2, the actuator simultaneously uses the first control mode to record the relative movement distance of the valve plate, in order to calculate the full stroke displacement value of the valve plate from the valve opening dead point to the contact point 2 between the valve plate and the valve seat. At this point, one-click debugging is completed, establishing the key position point identification and control function under conditions without position sensors or torque sensors. Note that the 10% to 30% of the actuator's maximum speed and the 30% to 80% of the actuator's rated torque are preferred values ​​in this embodiment. In other implementations, the parameters can be adjusted according to the application scenario and are not intended to limit the parameter values ​​of this invention.

[0086] One-click commissioning differs from the complex and cumbersome commissioning process of existing valve actuators, offering significant advantages: Simple operation, requiring no specialized electrical or mechanical knowledge, and commissioning can be completed without professional personnel; High deployment efficiency, with the entire commissioning process fully automated, significantly reducing commissioning time; High accuracy, based on torque feedback detection of the true mechanical limit position, with accuracy superior to most point-position sensors; High reliability, avoiding system deviations caused by human installation errors; Strong adaptability, particularly suitable for remote or unattended applications in complex environments where manual maintenance is difficult.

[0087] The first control mode accurately identifies the physical parameters of the three-phase AC asynchronous motor used by the actuator, such as stator resistance, rotor resistance, stator-rotor mutual inductance, and stator-rotor leakage inductance, as well as the actuator's moment of inertia. This is a prerequisite for valve position estimation in the first control mode. The identification of these parameters is a relatively mature existing technology and will not be elaborated upon here. In the absence of a physical valve position sensor, this invention uses the three-phase voltage output from the intelligent valve variable frequency vector drive controller to the three-phase AC asynchronous motor, and the three-phase current output from the intelligent valve variable frequency vector drive controller to the three-phase AC asynchronous motor obtained by the current monitoring module, integrating and estimating the valve position. The first control mode includes three steps: system modeling, speed estimation, and speed integration of position. First, a mathematical and physical model of the three-phase AC asynchronous motor used by the valve needs to be established. Then, based on the above model and the three-phase AC asynchronous motor speed estimation method, its real-time speed is estimated. Finally, the current valve position is obtained based on the real-time speed integration.

[0088] System modeling is the foundation for subsequent integration. Its purpose is to establish and simplify the mathematical and physical model of the three-phase AC asynchronous motor, transforming it from a complex, multivariable, nonlinear, and strongly coupled system into an observable and controllable linear model. Coordinate transformations, such as three-phase to two-phase coordinate transformation, two-phase to two-phase rotating coordinate transformation, and stationary to rotating coordinate transformation, are used to reduce the order and decouple the mathematical and physical model of the three-phase AC asynchronous motor. This includes using rotor field-oriented vector control models, slip frequency vector control models, stator field-oriented vector control models, air gap field-oriented vector control models, and direct torque control models. Speed ​​estimation refers to obtaining the real-time speed of the three-phase AC asynchronous motor based on the system model and speed estimation methods. Methods used include asynchronous motor speed estimation based on Model Reference Adaptive System (MRAS), asynchronous motor speed estimation based on Extended Kalman Filter (EKF), asynchronous motor speed estimation based on Sliding Mode Observer (SMO), and asynchronous motor speed estimation based on slip frequency method.

[0089] In most cases, the above methods can be used in combination. For example, MRAS and EKF can be used to switch between the two methods according to the speed, and weighted fusion can be performed in the transition region to improve the accuracy and applicability of the entire system. Alternatively, MRAS and slip can be used, with initial slip estimation and MRAS correction.

[0090] The methods described above are all existing technologies. Among them, the asynchronous motor speed estimation based on model reference adaptive theory (MRAS) involves establishing two sets of motor models, continuously comparing the outputs of the two models (usually flux linkage or current), and adjusting the estimated speed using an adaptive law to minimize the error between the two model outputs. The two sets of models are a reference model and an adjustment model. The reference model only depends on measurable quantities (stator current, voltage, etc.) and does not contain speed parameters; the adjustment model has a similar structure to the reference model but contains unknown speed variables. Specific implementation steps include establishing the stator voltage equation, calculating the stator flux linkage, establishing two sets of motor models, generating error signals, and designing the adaptive law. This speed estimation method offers high accuracy, good real-time performance, low computational requirements, and balanced performance, but its accuracy decreases in the medium-to-high speed range.

[0091] The asynchronous motor speed estimation based on extended Kalman filter (EKF) is a nonlinear state-space model of the asynchronous motor. EKF recursively estimates the speed through prediction and correction steps, including establishing the motor state equation and measurement equation, setting the initial state of the system, prediction and updating, and extracting the estimated speed. This method has high accuracy and strong anti-interference ability, but it requires high computing power and has general real-time performance.

[0092] The asynchronous motor speed estimation method based on slip frequency relies on the fact that the synchronous speed of the asynchronous motor is determined by the power supply frequency, while the actual rotor speed is slightly lower due to electromagnetic slip. The rotor speed can be obtained by calculating "synchronous speed - slip speed," which includes acquiring stator current and voltage, calculating stator flux linkage, extracting slip frequency, calculating synchronous angular velocity, and calculating rotor speed. This method offers high real-time performance but has lower accuracy and poor anti-interference capabilities.

[0093] System modeling ensures high-precision velocity and torque estimation even without position and torque sensors, thus supporting closed-loop control based on position integration and torque threshold positioning. System modeling is a mature existing technology, and its steps may include:

[0094] Sensors inside the drive controller collect three-phase current and voltage information. , ;

[0095] Clarke transformation (three-phase to two-phase coordinate transformation) yields , The formula for transforming the stator three-phase current and voltage from the three-phase stationary coordinate system to the two-phase stationary coordinate system is as follows:

[0096] ;

[0097] in, The current in the three-phase stator windings is expressed in amperes (A). The stator current component is given in an equivalent two-phase stationary coordinate system, in amperes (A).

[0098] Similarly, the stator voltage transformation formula is:

[0099] ;

[0100] Park transformation, two-phase to two-phase rotational transformation:

[0101] ;

[0102] in, and These are the current components in the synchronous rotating coordinate system, in amperes (A). It is an electrical angle, measured in rad, and is usually equal to the phase angle of the rotor flux linkage;

[0103] After Clarke and Park transformations, the state equations of the stator and rotor are derived based on the relationship between flux linkage and current. The stator flux linkage equation is as follows:

[0104]

[0105] ;

[0106] The rotor flux linkage equation is:

[0107] ;

[0108] in, It is the stator self-inductance (H); It is the mutual inductance (H) between the stator and the rotor; It is the rotor self-inductance (H); It is the stator current component (A); and It is the rotor current component (A);

[0109] The stator voltage equation is:

[0110] ;

[0111] ;

[0112] in , It is the stator voltage (V); It is the stator resistance (Ω);

[0113] The rotor voltage equation is:

[0114] ;

[0115] ;

[0116] in, It is the rotor resistance (Ω); It is the rotor self-inductance (H); It is the rotor angular velocity (rad / s);

[0117] The MRAS observer is constructed by using two parallel models (a reference model and an adjustable model) and adjusting the speed estimation in the adjustable model through error feedback to ensure consistency between the two outputs. Based on the aforementioned analysis, the stator voltage model is selected as the reference model, and the rotor flux current model is selected as the adjustable model. The flux estimation error is:

[0118] ;

[0119] ;

[0120] in, It is the rotor flux component estimated by the adjustable model; It is the rotor flux component calculated from the reference model;

[0121] An adaptive control law is a control law used to adjust the estimated speed based on the error. It typically employs an adaptive mechanism to adjust the estimated speed to compensate for the error. As the speed approaches zero, the rotational speed at this point is the final estimated rotational speed. The adaptive law can be expressed as:

[0122] ;

[0123] in, It is an adaptive gain parameter; It is the speed error, which is calculated through the flux linkage estimation error.

[0124] Position velocity integration refers to calculating the velocity integral based on the estimated real-time velocity using a fixed sampling period to obtain the current valve position. Simple and effective numerical velocity integration algorithms, such as rectangular integration, trapezoidal integration, or Simpson integration, can be used. Taking into account both the accuracy and real-time requirements of velocity integration, the valve position estimation results are ensured to be accurate and reliable.

[0125] Because the intelligent valve frequency converter vector drive controller used in this embodiment has strong computing power and high speed sampling frequency (sampling period 0.005s, sampling frequency 200Hz), the most suitable speed integration methods are trapezoidal integration and rectangular integration.

[0126] Trapezoid integral formula:

[0127] ;

[0128] Rectangular integral formula:

[0129] ;

[0130] in, The current position, in mm or rad; The position at the previous moment, in mm or rad; The parameters are given in vector frequency conversion control mode for the current speed. The velocity at the previous moment; The time step / sampling period is the time interval between two sampling points, in seconds. In the process of system modeling, velocity estimation, and velocity integration of position, technologies such as system model and velocity estimation methods are used and combined with the velocity integration method of position to realize the real-time position calculation of the valve.

[0131] Simpson's integral can also be used, with the following formula:

[0132] ;

[0133] The current position, in mm or rad; The position at the previous moment, in mm or rad; Position two cycles prior, in mm or rad; The current speed, in mm / s or rad / s, is given in vector frequency conversion control mode. The velocity at the previous instant, in mm / s or rad / s; The velocity two cycles ago, in mm / s or rad / s; Time step / sampling period, i.e., the time interval between two sampling points, in seconds.

[0134] Due to factors such as the accuracy of the integral model, errors in physical parameters, and aging of the mechanism, the valve position estimation method has a certain cumulative error, requiring calibration and compensation for position errors under the operating environment. Experiments show that the position estimation error exceeds 5% in most operating conditions. When the three-phase AC asynchronous motor used in the actuator is operating under the following conditions: low-speed operation (motor speed less than 20% of rated speed); high-speed operation (motor speed greater than rated speed); and high-load operation (motor load exceeding 50% of rated load), the position error exceeds 10%. Furthermore, the position error under these conditions exhibits obvious regularity and stability, making error compensation suitable. Since the first control mode has a regular cumulative error, integral error calibration and compensation are necessary and appropriate. Calibration can be performed using the two-dimensional grid sampling principle, and compensation can be performed using bilinear interpolation or its simplified method, ultimately controlling the position error within the allowable range. The calibration and compensation method for the valve position integral error is as follows:

[0135] The calibration method requires external equipment such as a dynamic torque calibration device to provide simulated speed and torque load during calibration and compensation testing, and continuous position sensors such as encoders to provide real-time position information. This section uses a valve actuator as an example to verify the calibration and compensation effects.

[0136] The calibration process employs a two-dimensional grid sampling setup, with velocity and torque values ​​evenly distributed across the actuator's maximum output range. At least 10 representative velocity values ​​(e.g., 10%, 20%, ... 100%) and at least 10 representative torque values ​​(e.g., 10%, 20%, ... 100%) are selected. By combining the velocity and torque values, a two-dimensional grid with at least 100 detection points is formed. In practice, 20 velocity values ​​and 10 torque values ​​can be selected, resulting in a two-dimensional grid with 200 detection points.

[0137] During calibration, the stroke length of the valve actuator is first set (usually the actual valve control stroke). Then, at each velocity and torque combination point on the two-dimensional grid, the actuator is controlled by a host computer to perform at least three complete reciprocating motions. During each motion, the estimated stroke of the actuator and the actual stroke measured by the position calibration device are recorded simultaneously. Finally, for each detection point, the arithmetic mean of the multiple measurements is taken as the final estimated stroke for that point. The difference between the estimated stroke and the actual stroke is the systematic error for that detection point. This systematic error is recorded and an error table is generated for subsequent compensation.

[0138] The calibration results show that the position integral error is lowest near low load and rated speed, and higher under low speed, high speed, and high load conditions. The integral error exceeds 5% in most calibration ranges, significantly impacting valve efficiency. The integral error exhibits strong regularity, classifying it as a systematic error suitable for compensation. Compensation can be achieved using bilinear interpolation to obtain the stroke error under the current torque and speed, with compensation and correction performed in each speed integral operation. Bilinear interpolation is a common two-dimensional interpolation method used to calculate the interpolation of a point within a known data grid; it is a prevalent two-dimensional interpolation method in engineering.

[0139] When calculating the current error using bilinear interpolation, it is first necessary to obtain the speed and torque of the current operating state. Find the four nearest known nodes in the error table. The error of the current operating state is calculated using the following bilinear interpolation formula:

[0140] ;

[0141] in, These are the two nearest velocity sampling nodes; These are the two nearest torque sampling nodes; This is the error compensation value after interpolation calculation; This represents the error compensation value measured at the node. After compensation, the error can be controlled between -1% and 2%, which is better than the ±5% tolerance range set in this invention.

[0142] The second control mode involves the valve opening / closing end stage, which is a crucial stage for searching contact point 2, confirming stop point 3, eliminating accumulated errors, and reconstructing the starting point 1 of the subsequent process. The following uses the valve opening / closing process of a gate valve as an example to fully illustrate the working process and execution effect of the intelligent electric valve actuator of this invention under conditions of no position sensor and no torque sensor feedback. The valve opening process execution curve is as follows: Figure 5 As shown, the valve closing process execution curve is as follows: Figure 6As shown in the diagram. Here, valve plate speed is the linear or angular velocity of the valve plate, expressed as a percentage of the maximum linear velocity; valve plate position is the opening / closing position of the valve plate relative to the valve seat, expressed as a percentage of the valve's full stroke, with 0% indicating the valve is fully closed and 100% indicating the valve is fully open; output torque is the torque output from the actuator to the valve, expressed as a percentage of the rated output torque, representing the force applied by the actuator to the valve and a key parameter determining whether the valve can open or close; torque limit is the upper limit of the output torque manually set during actuator operation, expressed as a percentage of the rated output torque. When the actuator detects that the output torque has reached this value, the intelligent valve frequency converter vector drive will take measures to prevent the output torque from continuing to increase; sealing pressure is the clamping force per unit contact area required to ensure reliable sealing between the valve plate and valve seat contact surfaces, typically expressed in MPa or N / mm².

[0143] During valve opening, the system first enters the first control mode, where the set stroke accounts for 90% of the total valve stroke. All percentage data related to stroke are based on the valve's full open / close stroke. In this embodiment, with a position estimation accuracy of ±2% for the first control mode, this 4x safety margin effectively prevents mechanical impact at the valve closing end. The actuator drives the valve from starting point 1 at 30% of its maximum speed for the first 20% of the total stroke, to the first speed change trigger point 4 (the low-speed operation during the first 20% stroke is to prevent water hammer). At the first speed change trigger point 4, the actuator drives the valve to accelerate to 90% of its maximum speed and continue operating to 90% of the total stroke, to the second speed change trigger point 5. At the second speed change trigger point 5, the actuator drives the valve to switch to the second control mode and decelerate to 20% of its maximum speed, operating at low speed to search for the contact point 2 between the valve plate and the valve seat. When the output torque is detected to continuously increase and reach a threshold (preferably 55% of the actuator's rated torque), it is determined that contact point 2 has been reached. The torque is stabilized for at least 3 seconds after which the torque exploration is complete. The valve opening process is now complete. This position is recorded as stop point 3 (100% position), and the position error generated by the first control mode is cleared.

[0144] During valve closing, the system first enters the first control mode. Similar to the valve opening process, the first control mode's set stroke accounts for 90% of the total valve stroke. The actuator drives the valve from the valve closing start point 1 (100% of the total stroke) at 90% of the actuator's maximum speed to the 10% position, reaching the first speed change trigger point 4. At the first speed change trigger point 4, the actuator switches the valve to the second control mode and decelerates to 20% of the maximum speed, operating at low speed to search for the contact point 2 between the valve plate and the valve seat. When the output torque is detected to be continuously increasing and reaching a threshold (preferably 55% of the actuator's rated torque), it is determined that contact point 2 has been reached. Then, the torque limit of the second control mode is increased to 55% of the actuator's rated output torque (this value is calculated based on the valve's required sealing specific pressure and can be adjusted according to actual needs). After this torque is maintained for 3 seconds, the valve closing process ends, and this position is recorded as stop point 3 (0% position), while simultaneously clearing the position error generated by the first control mode. In the second control mode, the valve operating torque is directly set and read by the intelligent vector frequency converter without the need for a torque sensor. The parameters related to stroke, speed, and torque, such as 90% stroke, 4 times safety margin, 20% maximum speed, 90% maximum speed, and 55% rated torque, can be adjusted according to the application scenario in different embodiments and are not intended to limit the invention.

[0145] This invention eliminates the need for valve position and torque sensors. By combining a second control mode with a first control mode, it achieves high-precision control of the valve opening and closing process without any physical valve position or torque sensor feedback. Compared to existing sensor-dependent control methods, this invention is more reliable and efficient, capable of efficiently and accurately completing valve opening / closing operations under various operating conditions. It is particularly suitable for electric valve control in extremely harsh environments, solving a series of problems faced by existing valve actuators that rely on position sensors, including poor environmental adaptability, low reliability, frequent maintenance, limited functionality, complex installation and debugging, and high cost. Throughout operation, it can smoothly switch between the first and second control modes, effectively identifying and acquiring the valve's contact point 2 and stop point 3, thereby ensuring the continuity and stability of the execution action. Even without using valve position and torque sensors, it can still achieve positioning and control effects comparable to existing sensor control.

[0146] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. A method for controlling an intelligent electric valve, characterized in that, The steps include the following: S100, when opening / closing the valve, the valve runs at high speed from the starting point in the first control mode to the stroke limit switching point and then switches to the second control mode. The first control mode is a valve position estimation mode based on speed numerical integration. First, the motor speed is converted into the valve plate speed, and then the real-time position of the valve plate is obtained according to the valve plate speed integration. S200: Run at low speed to the valve contact point in the second control mode. The second control mode is a torque threshold positioning control mode, which determines the contact position by monitoring changes in motor torque, accurately locating the valve opening / closing contact point and the stop point. The valve contact point is reached when the torque reaches the set threshold. S300. Continue to operate in the second control mode until the torque reaches a stable value, and stop at the set time. Stop the opening / closing of the valve at the stop point, reset the current position to the actual opening / closing position of the valve, and clear the valve plate position error accumulated in the first control mode to complete the position self-calibration. The starting point and the stopping point are the endpoint and the starting point of each other. The starting point position is the previous stopping point position or is obtained through one-click debugging search. An open / close valve closed loop is formed between the starting point and the stopping point, and steps S100-S300 are repeated.

2. The intelligent electric valve control method as described in claim 1, characterized in that, The travel limit switching point includes a first speed change trigger point. At the first speed change trigger point, the set target speed and torque limit are switched, and the system continues to operate in the first control mode.

3. The intelligent electric valve control method as described in claim 2, characterized in that, When the valve is opened, the first speed change trigger point corresponds to the acceleration start point after the end of the low-speed operation phase of the waterproof hammer; when the valve is closed, the first speed change trigger point corresponds to the deceleration start point at the beginning of the low-speed operation phase of the waterproof hammer.

4. The intelligent electric valve control method as described in claim 2, characterized in that, The travel limit switching point also includes a second speed change trigger point. At the second speed change trigger point, the system switches to the second control mode and reduces the operating speed to a set ratio of the maximum speed to ensure safe and stable identification of the valve contact point.

5. The intelligent electric valve control method as described in claim 1, characterized in that, The first control mode includes: The system modeling steps include establishing a mathematical and physical model of a three-phase AC asynchronous motor used to drive the valve, and using coordinate transformation to reduce the order and decouple the mathematical and physical model of the three-phase AC asynchronous motor. The speed estimation step involves obtaining the real-time speed of the three-phase AC asynchronous motor based on the mathematical and physical model; and The position is determined by the velocity integration step, which uses the real-time rotational speed obtained from the velocity estimation step to perform velocity integration calculations using a fixed sampling period, thereby obtaining the current position of the valve.

6. The intelligent electric valve control method as described in claim 5, characterized in that, It also includes calibration and compensation steps for valve position integral error, using a two-dimensional grid sampling method for calibration and a bilinear interpolation method for compensation, so as to control the position error within the allowable range.

7. The intelligent electric valve control method as described in claim 1, characterized in that, It also includes a one-click debugging step, used for position initialization and stroke calibration after the valve actuator is first installed, after important parameters are modified, or when position information is lost due to accidental power failure. It uses the second control mode to automatically search for the valve plate's opening dead point, the contact point between the valve plate and the valve seat, and the valve plate's full stroke displacement value between the valve plate's opening dead point and the contact point between the valve plate and the valve seat.

8. The intelligent electric valve control method as described in claim 7, characterized in that, The one-click debugging steps include: The valve moves slowly along the valve opening direction in a low-speed, low-torque second control mode, and the torque change is monitored in real time to identify the valve opening dead point. After identifying the valve opening dead point, the operating direction is switched, and the valve continues to move slowly along the valve closing direction in a low-speed, low-torque second control mode, while real-time monitoring of torque changes to identify the valve-seat contact point; and The relative movement distance of the valve plate is recorded synchronously using the first control mode in order to calculate the full stroke displacement value of the valve plate from the valve plate's opening dead point to the contact point between the valve plate and the valve seat.

9. An intelligent electric valve control device, characterized in that, Used to implement the intelligent electric valve control method according to any one of claims 1-8.

10. An intelligent electric valve actuator, characterized in that, The intelligent electric valve control method according to any one of claims 1-8 achieves high-precision control of valve opening and closing.

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