An electric valve / gate and its control device and control method

Abstract

An electric valve / gate, its control device, and control method are disclosed. The electric valve / gate includes a control device comprising an AC asynchronous motor, a transmission device, and a valve actuator. The valve actuator is connected to the AC asynchronous motor, and the AC asynchronous motor is connected to the valve / gate via the transmission device. The valve actuator acquires real-time torque information of the AC asynchronous motor or the valve / gate, and uses a set torque of the valve actuator as input and the real-time torque as feedback. A PID control algorithm is used to instantly correct the output torque or output torque limit of the valve actuator, thereby adjusting the output torque driving the AC asynchronous motor in real time to meet the response speed and control accuracy requirements of each stage of the valve / gate's opening and closing process. The invention also provides a control method for this electric valve / gate.

Description

Technical Field

[0001] This invention relates to valve / gate control technology, and in particular to an electric valve / gate and its control device and control method. Background Technology

[0002] Most existing valve / gate electric actuators use a direct-start AC asynchronous motor, which is then driven by a driver to move the mechanical transmission mechanism and open / close the valve. AC asynchronous motors are widely used in valve / gate electric actuators due to their simple structure, reliable operation, light weight, low cost, and high starting torque. However, the following problems exist during their use:

[0003] 1) The torque control accuracy of AC asynchronous motors is low, and the dynamic range of torque and speed is small (peak torque and speed are limited). In addition, factors such as medium temperature, foreign objects, and corrosion can affect the driving torque of AC asynchronous motors, which cannot overcome the resistance torque, resulting in the valve / gate not being able to open when opening. During the operation of the valve / gate, the speed of AC asynchronous motor is fixed, and the opening / closing speed is constant. When the valve reaches the stop point, it causes the dynamic load of the valve seat to be overloaded, resulting in the valve / gate not being able to open after it is tightly closed.

[0004] 2) The valve opening / closing stopping method adopts point-to-point triggering, that is, a limit switch (or reed switch) is set at the valve body at the valve opening / closing stopping point, and the valve / gate stops according to the limit switch (or reed switch) arrival signal; due to the inherent mechanical clearance of the limit switch (or reed switch) and the large error in repeatability control accuracy, the valve / gate may not stop completely or may not stop after being completely closed, resulting in internal leakage of the valve / gate or the AC asynchronous motor being unable to stop and burning out; in addition, the point-to-point triggering stopping method cannot achieve high-precision position control throughout the entire stroke, and the operator cannot obtain the real-time position information of the valve / gate;

[0005] 3) The force on the valve seat when the valve is fully closed cannot be controlled, which can easily cause the valve / gate to not close tightly, resulting in internal leakage; the wear, aging, and electrical parameter drift of the valve / gate during long-term use can cause changes in its characteristics, resulting in a large error between the theoretical output value and the actual output value, and the force on the valve seat when the valve is fully closed is unstable.

[0006] 4) The differences in physical characteristics of AC asynchronous motors were not taken into account, resulting in poor torque, speed and position control accuracy, small dynamic range of torque and speed, and inconsistent performance of batch products. Summary of the Invention

[0007] The technical problem to be solved by the present invention is to provide an electric valve / gate and its control device and control method, which addresses the above-mentioned deficiencies of the prior art.

[0008] To achieve the above objectives, the present invention provides a control device for an electric valve / gate, comprising an AC asynchronous motor, a transmission device, and a valve actuator. The valve actuator is connected to the AC asynchronous motor, and the AC asynchronous motor is connected to the valve / gate via the transmission device. The valve actuator acquires real-time torque information of the AC asynchronous motor or the valve / gate, and uses the set torque of the valve actuator as input and the real-time torque as feedback. A PID control algorithm is then used to instantly correct the output torque or output torque limit of the valve actuator, thereby adjusting the output torque driving the AC asynchronous motor in real time to meet the response speed and control accuracy requirements of each stage of the valve / gate's opening and closing process.

[0009] The aforementioned electric valve / gate control device includes a valve actuator comprising a housing and a logic control module, a frequency converter control module, and a frequency converter drive module installed within the housing. The frequency converter drive module is connected to the AC asynchronous motor. The logic control module is connected to the frequency converter drive module via the frequency converter control module. The logic control module adjusts the output torque or output torque limit of the frequency converter drive module in real time via the frequency converter control module. The logic control module includes a torque setting unit, which sets the corresponding set torque according to the requirements of each stage of the valve / gate opening and closing process.

[0010] The torque output unit sends the set torque to the variable frequency drive module, and the variable frequency drive module drives the AC asynchronous motor to perform corresponding valve / gate opening or closing actions with the set torque as the output torque or the output torque limit.

[0011] The real-time torque detection unit acquires the real-time torque of the AC asynchronous motor or valve / gate during operation; and

[0012] The torque correction unit uses a PID control algorithm to correct the output torque or output torque limit based on the real-time torque and the set torque, and transmits the corrected output torque or output torque limit to the torque output unit. The torque output unit transmits the corrected output torque to the variable frequency drive module through the variable frequency control module, and the variable frequency drive module drives the AC asynchronous motor to respond in real time.

[0013] The control device for the electric valve / gate described above, wherein the logic control module further includes an output current detection unit connected to the real-time torque detection unit, the output current detection unit detects the physical parameters of the AC asynchronous motor and transmits them to the real-time torque detection unit, the real-time torque detection unit calculates the real-time torque and transmits it to the torque correction unit, the physical parameters include stator resistance, rotor resistance, stator-rotor mutual inductance, stator-rotor leakage inductance and / or no-load current.

[0014] The aforementioned electric valve / gate control device further includes a torque sensor for acquiring the real-time torque. The torque sensor is mounted on the output shaft of the AC asynchronous motor, the output shaft of the valve reduction gearbox, or the valve drive mechanism, and is connected to the real-time torque detection unit or frequency converter control module, transmitting the measured real-time torque signal to the real-time torque detection unit or frequency converter control module. The aforementioned electric valve / gate control device also includes a position sensor. The logic control module further includes a speed control unit connected to the position sensor, used to acquire the feedback signal from the position sensor to obtain the current valve speed, correct the output speed of the AC asynchronous motor using a PID control algorithm, and superimpose the correction with the torque correction unit to correct the output torque, thereby meeting the speed requirements of each stage of valve / gate opening or closing.

[0015] The aforementioned electric valve / gate control device further includes a logic control module that is connected to the position sensor. This module is used to determine whether the valve / gate has reached the position node of each stage of the valve / gate opening or closing process based on the feedback signal from the position sensor. Based on the determination result, the output torque is further adjusted to meet the control logic and stop position accuracy requirements of each stage of the valve / gate opening or closing process.

[0016] In the aforementioned control device for electric valves / gates, the position sensor is a full-stroke sensor and / or a point-position sensor, and the position sensor is installed on the output shaft of the AC asynchronous motor, the output shaft of the gearbox of the transmission device, or the valve drive mechanism.

[0017] The aforementioned electric valve / gate control device further includes a torque calibration device, which is detachably connected to the AC asynchronous motor and connected to the logic control module, for calibrating the torque of the AC asynchronous motor to correct the output torque of the valve actuator.

[0018] To better achieve the above objectives, the present invention also provides a control method for an electric valve / gate. The method employs the aforementioned control device for the electric valve / gate, which collects real-time torque information of the AC asynchronous motor or valve / gate operation, uses the set torque of the valve actuator as input, and the real-time torque as feedback. A PID control algorithm is then used to instantly correct the output torque of the valve actuator, thereby adjusting the output torque driving the AC asynchronous motor in real time to meet the requirements of the valve / gate's opening and closing process control strategy.

[0019] To better achieve the above objectives, the present invention also provides an electric valve / gate, wherein the control device for the electric valve / gate described above is included.

[0020] The technical effects of this invention are as follows:

[0021] This invention uses a set torque as input and the real-time torque of the detected AC asynchronous motor or valve / gate as feedback. It employs a PID control algorithm to correct the output torque during the drive process, adjusting the output torque in real-time based on the real-time torque. This achieves closed-loop torque control for the opening and closing of the electric valve / gate, effectively improving the output torque response speed and control accuracy. Furthermore, this invention can also use a multi-layered PID nesting approach to establish torque loops (or current loops), speed loops, and position loops from the inside out. The closed-loop level or nesting depth can be selected according to the needs of different stages of the valve / gate execution process. By optimizing the matching parameters of speed and torque, it can achieve precise control of the torque, speed, and position of a common AC asynchronous motor based on the load changes throughout the valve / gate's stroke, ensuring that the valve / gate is "closed tightly," "stopped accurately," and "opened smoothly." Simultaneously, based on the valve / gate's starting, acceleration, constant speed, deceleration, slow approach, torque control, and stopping stages, it can achieve staged combined control, meeting the requirements for rapid valve / gate opening and closing, water hammer elimination, regulating valve operating conditions, and fault handling. Short-term "overclocking" can also be used. (Overspeed) and "overcurrent" (overtorque) allow for the use of smaller rated AC asynchronous motors in valve actuators compared to existing technologies, thereby reducing product size and weight and lowering costs, improving the dynamic characteristics of pipeline systems; while improving the load smoothness control of ordinary AC asynchronous motors, it can also reduce the impact on the power grid.

[0022] 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

[0023] Figure 1 This is a schematic diagram of an electric valve / gate structure according to an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of an electric valve / gate structure according to another embodiment of the present invention;

[0025] Figure 3 This is a block diagram of an electric valve / gate structure according to an embodiment of the present invention;

[0026] Figure 4 This is a block diagram of a valve actuator structure according to an embodiment of the present invention;

[0027] Figure 5 This is a block diagram of a valve actuator structure according to another embodiment of the present invention;

[0028] Figure 6 This is a schematic diagram of a logic control module according to an embodiment of the present invention;

[0029] Figure 7 This is a schematic diagram of a frequency converter control module according to an embodiment of the present invention;

[0030] Figure 8 This is an equivalent circuit diagram for stator resistance identification according to an embodiment of the present invention;

[0031] Figure 9 This is an equivalent circuit diagram of motor T according to an embodiment of the present invention;

[0032] Figure 10 This is an equivalent circuit diagram of the motor anti-Γ according to an embodiment of the present invention;

[0033] Figure 11 This is a diagram showing the relationship between the set torque and the output torque in the torque calibration of an embodiment of the present invention.

[0034] Among them, the attached reference numerals

[0035] 1 Valve / Gate

[0036] 2. Transmission device

[0037] 21 Gearbox

[0038] 22 Valve drive mechanism

[0039] 3. AC asynchronous motor

[0040] 4 Valve actuators

[0041] 41 Logic Control Module

[0042] 42 Variable Frequency Control Module

[0043] 43 Variable Frequency Drive Module

[0044] 44 Core Controller

[0045] 45 Signal Conversion Module / I / O Module

[0046] 46 Detection and Protection Module

[0047] 47 Temperature Control Module

[0048] 48 Human-Computer Interaction Module

[0049] 5. Torque calibration device

[0050] 6 position sensors

[0051] 7 Torque Sensor

[0052] 8 Power Supply Detailed Implementation

[0053] The structural and working principles of the present invention will be described in detail below with reference to the accompanying drawings:

[0054] See Figures 1-3 , Figure 1 This is a schematic diagram of an electric valve / gate structure according to an embodiment of the present invention. Figure 2 This is a schematic diagram of an electric valve / gate structure according to another embodiment of the present invention. Figure 3 This is a block diagram of an electric valve / gate according to an embodiment of the present invention. Addressing the problems of valves / gates in the prior art, such as "unable to open," "unable to close tightly," and "unable to stop accurately," the present invention matches different control strategies according to various operating conditions of the valve / gate at the application site. For example, it prioritizes valve opening / closing efficiency (time), valve opening / closing position accuracy, valve opening / closing torque accuracy, valve opening / closing safety, pipeline opening / closing safety, and pipeline system stability. The invention provides an electric valve / gate that satisfies the above execution strategies, along with its control device and control method. The electric valve or gate of the present invention includes a valve / gate 1 and a control device. The control device includes a transmission device 2, an AC asynchronous motor 3, and a valve actuator 4. The AC asynchronous motor 3 is connected to the valve / gate 1 via the transmission device 2. The valve actuator 4 is connected to both a power supply 8 and the AC asynchronous motor 3, and controls the opening and closing of the valve / gate 1 through the AC asynchronous motor 3. The transmission device 2 may include a reduction gearbox 21 and a valve drive mechanism 22. The reduction gearbox 21 is connected to both the output shaft of the AC asynchronous motor 3 and the input end of the valve drive mechanism 22. The output end of the valve drive mechanism 22 is connected to the valve / gate 1 to drive the valve / gate 1. The valve actuator 4 and the AC asynchronous motor 3 may be an integral connecting piece (see...). Figure 1 ); or the valve actuator 4 and the AC asynchronous motor 3 are separately configured and connected by cable or wirelessly (see Figure 2 This allows for the separation of mechanical and electrical drives, meeting the requirements of demanding application environments such as limited installation space, high temperature, radiation, high humidity, and strong magnetic interference. The composition, structure, relative positions, connections, and working principles of other components of the electric valve / gate of this invention are all mature existing technologies, and therefore will not be elaborated upon here. The following will only provide a detailed description of the control device and its working principle.

[0055] The control device of the present invention acquires the real-time torque information of the AC asynchronous motor 3 or the valve / gate 1 through the valve driver 4, and uses the set torque of the valve driver 4 as input and the real-time torque as feedback. It uses a PID control algorithm to make real-time corrections to the output torque or output torque limit of the valve driver 4, so as to adjust the output torque driving the AC asynchronous motor 3 in real time and meet the response speed and control accuracy requirements of the valve / gate 1 in each stage of the opening and closing process.

[0056] See Figure 4 and Figure 5 , Figure 4 This is a structural block diagram of a valve actuator 4 according to an embodiment of the present invention. Figure 5 This is a structural block diagram of a valve actuator 4 according to another embodiment of the present invention. The valve actuator 4 of the present invention includes a housing and a logic control module 41, a frequency conversion control module 42, and a frequency conversion drive module 43 installed in the housing. The frequency conversion drive module 43 is connected to an AC asynchronous motor 3. The logic control module 41 is connected to the frequency conversion drive module 43 through the frequency conversion control module 42. The logic control module 41 adjusts the output torque or output torque limit of the frequency conversion drive module 43 in real time through the frequency conversion control module 42.

[0057] See Figure 6 , Figure 6 This is a schematic diagram of a logic control module according to an embodiment of the present invention. The logic control module 41 of this embodiment can be used for overall machine logic control, and can store and execute control programs. The logic control module 41 can be a microcontroller, DSP, PLC, etc., and may include a program memory, data memory, central processing unit (CPU), I / O interface, internal bus, etc. The logic control module 41 of this embodiment mainly includes: a torque setting unit, used to set the corresponding set torque according to the requirements of each stage of the valve / gate 1's opening and closing process; a torque output unit, connected to the torque setting unit and the frequency conversion control module 42 respectively, sending the set torque to the frequency conversion drive module 43, the frequency conversion drive module 43 driving the AC asynchronous motor 3 to perform the corresponding valve / gate 1 opening or closing action with the set torque as the output torque or the output torque limit; and a real-time torque detection unit, connected to the AC asynchronous motor 3 or the transmission device 2 of the valve / gate 1, and used to obtain the torque of the AC asynchronous motor 3. The system includes a real-time torque measurement unit for valve / gate 1 operation and a torque correction unit, which is connected to the torque setting unit, real-time torque detection unit, and torque output unit, respectively. The torque correction unit corrects the output torque based on the real-time torque and the set torque output by the torque setting unit, and transmits the corrected output torque to the torque output unit. The torque correction unit, using the set torque as input and the real-time torque as feedback, employs a PID control algorithm to correct the output torque or output torque limit, and transmits the corrected output torque to the torque output unit. The torque output unit then transmits the corrected output torque or output torque limit to the frequency converter drive module 43 via the frequency converter control module 42. The frequency converter drive module 43 drives the AC asynchronous motor 3 to respond in real-time.

[0058] To further improve control accuracy, in this embodiment, the control device also includes a position sensor 6, and the logic control module 41 also includes a speed control unit connected to the position sensor 6. The speed control unit is used to obtain the current speed of the valve by using an open-loop vector control method or by collecting the feedback signal from the position sensor 6, correcting the output speed of the AC asynchronous motor 3 through a PID control algorithm, and superimposing the correction of the output torque with the torque correction unit to meet the speed requirements of each stage of opening or closing of the valve / gate 1.

[0059] In another embodiment of the present invention, the logic control module 41 may further include a position control unit connected to the position sensor 6, used to determine whether the position node of each stage of the valve / gate 1 opening or closing process has been reached according to the feedback signal of the position sensor 6, and further adjust the output torque according to the determination result to meet the control logic and stop position accuracy requirements of each stage of the valve / gate 1 opening or closing. This embodiment can monitor the position, speed, and torque of the valve / gate 1 in real time. According to the nesting relationship, a nested control mode of torque loop, speed loop, and position loop can be adopted from the inside out. Among them, the torque loop directly affects the torque, has fast response and high accuracy, and can meet the requirements of real-time control of motor output torque; the speed loop works on the basis of the torque loop, obtains the current speed of the valve / gate 1 from the feedback of the valve actuator 4 or the position sensor 6 through the basic principle of open-loop vector control, and applies influence through the torque loop to meet the speed requirements of different stages; the position loop, as an optional and supplementary item, works on the basis of the speed loop and the torque loop, and is the outermost adjustment. It judges and adjusts the output according to the feedback of the valve actuator 4 or the position sensor 6 to meet the control logic and stop position accuracy requirements.

[0060] The position sensor 6 can be a full-stroke sensor and / or a point-position sensor to achieve high-precision position control throughout the entire stroke. The position sensor 6 can be installed on the output shaft of the AC asynchronous motor 3, the output shaft of the valve reduction gearbox 21, or the input or output shaft of the valve drive mechanism 22, and is connected to the logic control module or frequency converter control module through the signal conversion module / IO module 45. This invention is compatible with both full-stroke and point-position sensors and is applicable to combinations of full-stroke, point-position, and full-stroke and point-position sensors. In practice, the selection of the position sensor 6 is related to the type of valve / gate 1, the mechanical structure characteristics of the valve / gate 1, the operating environment of the valve / gate 1, and the manufacturing technology level of the valve / gate 1, and generally does not change due to the requirements of the valve actuator 4. In a system pre-installed with a full-stroke sensor, the different stages of valve / gate 1 execution are accurately divided based on continuous position signals (this invention may include a start-up stage, acceleration stage, constant speed stage, deceleration stage, slow approach stage, torque control stage, and stop stage, etc.). Parameters such as the start position, end position, speed, torque, acceleration, and deceleration of each stage are rationally controlled to achieve the desired execution effect. This invention, in conjunction with different interface conversion hardware, can adapt to various types of full-stroke sensors.

[0061] Among them, point-position sensors still account for a certain proportion in valve actuation systems due to their low cost, convenient installation, and strong environmental adaptability. In systems pre-installed with point-position sensors, different processes of valve actuation are identified and divided based on discrete point position signals, ensuring the opening or closing execution result while ensuring safety. In systems pre-installed with both full-stroke sensors and point-position sensors, similar to systems pre-installed only with full-stroke sensors, the point-position sensors serve as protective devices or safety redundancy devices for safety protection at extreme or special positions. The compatibility of this invention with different sensor types and forms broadens its application scope and applicable environment, and also improves the safety of its application process.

[0062] See Figure 7 , Figure 7 This is a schematic diagram of a variable frequency control module according to an embodiment of the present invention. The variable frequency control module 42 of this embodiment can be built from a microcontroller or DSP chip and peripheral circuits, or it can be used to generate the characteristic parameters of the motor and torque vector control algorithm. With the cooperation of the inverter circuit of the variable frequency drive module 43, it drives the AC asynchronous motor 3. It may include a program memory, a data memory, a central processing unit (CPU), an I / O interface, and an internal bus, etc.

[0063] like Figure 5As shown, the logic control module 41 and the frequency conversion control module 42 can be integrated into a core controller 44. The frequency conversion drive module 43 is connected to the core controller 44 and the AC asynchronous motor 3 respectively. The core controller 44 and the frequency conversion drive module 43 can also be integrated into a drive module. The core controller 44 adjusts the output torque or output torque limit of the frequency conversion drive module 43 in real time to meet the requirements of the valve / gate 1 control strategy; or the logic control module 41, the frequency conversion control module 42, and the frequency conversion drive module 43 can also be integrated into a drive module. That is, the logic control, frequency conversion control, and drive output functions of the valve actuator 4 can be set separately on different modules, or they can be integrated into one module. This invention does not limit the structure, composition, and integration method of the specific functional modules inside the valve actuator 4, as long as the function of adjusting the output torque or output torque limit of the frequency conversion drive module 43 in real time to meet the requirements of the valve / gate 1 control strategy can be achieved.

[0064] Among them, the core controller 44 serves as the core of signal judgment and logic control, preferably a microcontroller or DSP, and can be equipped with a logic processor, I / O system, internal bus, etc.; the frequency conversion drive module 43 serves as the basic module of vector frequency conversion control, and can be equipped with a digital signal processor, power conversion circuit, power drive circuit, etc. Figure 4 and Figure 5As shown, the valve actuator 4 may also include a wireless communication module, a detection and protection module 46, an I / O module, a human-machine interface module 48, a fieldbus module, a measurement conversion module, a temperature control module 47, a power supply battery, and cable connectors. The wireless communication module is used for connection and information exchange with a remote control and external portable devices, and may include infrared transceiver circuits, Bluetooth communication circuits, and interfaces such as infrared communication, Bluetooth communication, serial bus communication, and Ethernet communication, which can meet the wired or wireless connection requirements of the valve actuator 4 with the torque calibration device 5, a host computer, a cloud server, etc. The detection and protection module 46 is used for rectification, filtering, and inversion of electrical energy when driving the AC asynchronous motor 3, and may include a rectifier circuit, a DC circuit, an inverter circuit, and a detection circuit. The I / O module is used for inputting and outputting signals. The connection, conversion, and protection components may include I / O power supply circuits, digital input circuits, digital output circuits, analog input circuits, and analog output circuits. The human-machine interface module 48 is used for parameter and command input and display of operating status and alarm information, and may include a display screen and button panel. The fieldbus module is used for information exchange with the host computer and external monitoring equipment, and may include Modbus bus, CAN bus, etc. The measurement conversion module is used to convert the sinusoidal voltage signal, TTL rectangular wave signal, and HTL rectangular wave signal acquired by the encoder into an open-collector signal and feed it back to the logic control module 41, and may include signal conversion circuits, high-speed counting circuits, etc. The temperature control module 47 is used for overall machine temperature control and may include a temperature sensor, cooling fan, aluminum heat sink, etc. This valve actuator 4 can be used for all action control, information display, alarm, and protection of the valve / gate 1.

[0065] Figure 5 In the illustrated embodiment, a torque sensor 7 may also be included to acquire the real-time torque. The real-time torque can be directly acquired through the torque sensor 7. The torque sensor 7 may be installed on the output shaft of the AC asynchronous motor 3, the output shaft of the valve reduction gearbox 21, or the valve drive mechanism 22, and connected to the real-time torque detection unit. The measured real-time torque signal is transmitted to the real-time torque detection unit so that the torque correction unit can use a PID control algorithm to correct the output torque or the output torque limit.

[0066] Figure 4In the illustrated embodiment, the logic control module 41 further includes an output current detection unit connected to the real-time torque detection unit. That is, the real-time torque is preferably obtained by combining the output current detection result with a vector transformation method. The output current detection unit detects the physical parameters of the AC asynchronous motor and transmits them to the real-time torque detection unit. The real-time torque detection unit calculates the real-time torque and transmits it to the torque correction unit. For example, the physical parameters can be detected and obtained by the current detection circuit in the logic control module or the frequency converter control module. The physical parameters may include stator resistance, rotor resistance, stator-rotor mutual inductance, stator-rotor leakage inductance, and / or no-load current.

[0067] Specifically, the three-phase AC signal of the AC asynchronous motor 3 can be converted into the torque component i of the stator current through coordinate transformation. sT The excitation component i of the stator current sM The real-time torque is calculated using different methods depending on the magnetic field orientation: rotor magnetic field orientation vector control, direct torque control, slip frequency vector control, stator magnetic field orientation vector control, or air gap magnetic field orientation vector control. In other words, vector torque control is used as the output method, and the detection result of the torque detection circuit (preferably the output current detection circuit in this embodiment) is used as the feedback signal. The output torque is adjusted and controlled through a PID closed-loop system to ensure that the actual output torque of the driven valve / gate 1 operates within the set torque, i.e., the desired value.

[0068] To achieve more precise vector control, this invention can also identify the physical parameters of the AC asynchronous motor 3 through the valve actuator 4. Firstly, parameters such as stator resistance, rotor resistance, stator-rotor mutual inductance, and stator-rotor leakage inductance of the AC asynchronous motor 3 are collected to ensure the accuracy of the basic parameters in torque vector control. That is, the logic control module 41 can also include a physical parameter identification unit to acquire the physical parameters of the AC asynchronous motor 3 for more accurate torque vector control. AC and DC excitation signals can be input to the AC asynchronous motor 3, and stator current feedback can be monitored in real time. The aforementioned relevant parameters are calculated based on the voltage and current values ​​and phase relationships. The no-load current is used to estimate the torque consumption (such as friction, ventilation, core loss, etc.) during the operation of the AC asynchronous motor 3 and to compensate for its output torque. This no-load current is preferably 20% to 50% of the motor's rated current.

[0069] This embodiment uses an output current detection circuit for parameter detection, collects and calculates the real-time torque (which can be calculated from the rotor equivalent self-inductance, rotor equivalent mutual inductance, rotor flux linkage, and stator current torque components) as feedback, and uses PID control principles to perform closed-loop control and correction of the output torque, ultimately achieving torque vector control to ensure the torque response speed and control accuracy during valve / gate 1 operation. The stator resistance in this embodiment can be obtained in the following way:

[0070] When controlling the inverter to output a single-phase DC voltage, the motor circuit diagram in this case can be simplified as follows: Figure 8 As shown:

[0071]

[0072] Among them, V` dc =DC voltage, R1 = Stator resistance.

[0073] Due to the voltage drop across the switching transistors, the actual voltage applied to the stator will have a certain error. To eliminate this error, multiple different voltage signals can be applied, and the slope between the stator voltage and stator current can be used as the stator resistance.

[0074]

[0075] The rotor resistance, stator-rotor mutual inductance, and stator-rotor leakage inductance in this embodiment can be obtained in the following way:

[0076] The electromagnetic phenomena of the AC asynchronous motor 3 under single-phase sinusoidal signal excitation are basically the same as those under three-phase sinusoidal signal excitation. This method can be used for identification. At the same time, the motor torque is zero and the motor remains stationary. The equivalent circuit of the motor at this time can be replaced by a three-phase equivalent circuit.

[0077] The vector equations of the stator and rotor of the AC asynchronous motor 3 are as follows:

[0078]

[0079] in, p is the differential operator, R1 is the stator resistance, and R r L is the rotor resistance. sσ For stator leakage inductance, L rσ For rotor leakage inductance, L m The mutual inductance between the stator and rotor is given, where ω is the rotor speed, and the rotor is a squirrel-cage type.

[0080] The output W phase is disconnected, and the U and V phases are controlled by the H-bridge sinusoidal voltage modulation signal to switch the inverter on and off, thereby generating a sinusoidal voltage excitation signal. Let the sinusoidal voltages of the U and V phases be... The phase voltage and phase current in AC asynchronous motor 3 satisfy the following relationship:

[0081]

[0082]

[0083] Among them, V Un V Vn V wn These are the U-phase, V-phase, and W-phase relative midpoint voltages, respectively.

[0084] At this point, the motor torque is 0, and the T-type equivalent circuit diagram of the motor at this time is as follows. Figure 9 As shown, under normal circumstances, the stator leakage inductance is the same as the rotor leakage inductance, i.e., L. sσ =L rσ . Figure 10 The equivalent circuit diagram of the motor inverse Γ according to an embodiment of the present invention is a circuit after equivalent transformation of T. The relationship between the circuit parameters and the equivalent circuit parameters of the T-type circuit after the transformation is as follows:

[0085]

[0086]

[0087]

[0088] From the diagram, we can see that:

[0089]

[0090]

[0091] In the above formula It is the initial phase of the voltage. It is the initial phase of the current.

[0092] From equations (1-6) to (1-9), we can obtain:

[0093]

[0094] The impedance expression can be derived from the inverse Γ equivalent circuit as follows:

[0095]

[0096] A single-phase test was conducted on the AC asynchronous motor 3 by applying sinusoidal voltage signals with frequencies f1 and f2 respectively. The equivalent impedance of the stator current molecule was detected, and R`(f) = R - R1 was set. From equation (1-12), the calculation formula for the motor parameters under the inverse Γ equivalent circuit can be obtained.

[0097]

[0098]

[0099]

[0100] Based on the parameter conversion relationship between the T-type equivalent circuit and the inverse Γ equivalent circuit (1-5), the calculation formulas for the motor rotor resistance, stator-rotor mutual inductance, and stator-rotor leakage inductance can be obtained as follows:

[0101]

[0102]

[0103] L sσ =L rσ =L` sσ +L` m -L m (1-18)

[0104] In one embodiment of the present invention, rotor field orientation vector control is preferably used. The field orientation is performed according to the rotor's total flux linkage vector direction, and the real-time torque T is obtained using the following formula. ei :

[0105]

[0106] Where, n p L represents the number of pole pairs of the AC asynchronous motor 3. md L represents the equivalent mutual inductance of one phase winding when the stator and rotor of the AC asynchronous motor 3 are coaxial. rd i is the equivalent self-inductance of one phase winding of the rotor of the AC asynchronous motor 3. sT Ψ is the torque component of the stator current of the AC asynchronous motor 3. r The rotor flux linkage of the AC asynchronous motor 3.

[0107] Its control principle is as follows:

[0108]

[0109]

[0110]

[0111] Among them, Ψ rM The M-axis component of the rotor's total flux linkage; Ψ rT i is the T-axis component of the rotor's total flux linkage; rM i is the M-axis component of the rotor current; rT n is the T-axis component of the rotor current;p This represents the number of pole pairs of the motor. This is the equivalent self-inductance of one phase winding of the rotor; The equivalent mutual inductance of one phase winding when the stator and rotor are coaxial; i sT The torque component of the stator current; Ψ r For rotor flux linkage; is the rotor electromagnetic time constant; p is the differential operator; i sM This is the excitation component of the stator current.

[0112] In another embodiment of the present invention, direct torque control can also be used, and the real-time torque T can be obtained using the following formula. ei :

[0113]

[0114] Where, n p L represents the number of pole pairs of the AC asynchronous motor 3. m For the mutual inductance between the stator and rotor, L s For, L r For, Ψ s For stator flux linkage, Ψ r For rotor flux linkage, θ sr The torque angle is a vector Ψ. s and Ψ r The angle between them.

[0115] This direct torque control is based on the mathematical model of the stator shaft system and uses the space vector analysis method to achieve motor control. Its control principle is as follows:

[0116] Stator flux linkage equation:

[0117]

[0118] Among them, u s This is the voltage vector of the stator shaft system.

[0119] Ignore stator resistance and voltage drop R s i s ,have:

[0120] Ψ≈∫u s dt (2-18)

[0121] The torque equation is:

[0122]

[0123] θ sr The torque angle is a vector Ψ. s and Ψ r The angle between them.

[0124] In the third embodiment of the present invention, slip frequency vector control can be used to orient the magnetic field according to the slip frequency vector, and the real-time torque T can be obtained using the following formula. ei :

[0125]

[0126] Where, n p T represents the number of pole pairs of the AC asynchronous motor 3. r L is the rotor electromagnetic time constant. rd Ψ is the equivalent self-inductance of one phase winding of the rotor of the AC asynchronous motor 3. r For rotor flux linkage, ω s1 This is the slip angular frequency.

[0127] Slip frequency vector control can be performed based on rotor magnetic field fixed vector control, and its control principle is as follows:

[0128]

[0129]

[0130] Where, ω s1 This is the slip angular frequency.

[0131] In the fourth embodiment of the present invention, stator magnetic field orientation vector control is adopted. The magnetic field is oriented according to the direction of the stator flux linkage vector, and the real-time torque T is obtained using the following formula. ei :

[0132] T ei =n p Ψ s i sT ;

[0133] Where, n p Ψ is the number of pole pairs of the AC asynchronous motor 3. s i is the stator flux linkage of the AC asynchronous motor 3. sT This refers to the torque component of the stator current of the AC asynchronous motor 3. In this embodiment, the magnetic field is oriented according to the stator flux linkage vector direction, and its control principle is as follows:

[0134]

[0135] T ei =n p Ψ s i sT (2-7)

[0136]

[0137] Among them, Ψ s For stator flux linkage; Ψ sM The stator's total flux linkage M-axis component; Ψ sT The T-axis component of the stator's total flux linkage; The leakage flux coefficient is given by equation (2-8). The stator flux linkage Ψ is given by equation (2-8). s is i sT and i sM The functions are coupled to each other, so a decoupling controller needs to be added. The control principle is as follows:

[0138]

[0139]

[0140] in, The stator current excitation component is given; Given the stator flux linkage; i MT To decouple the control signal, substituting equation (2-9) into the first equation of equation (2-8) yields:

[0141]

[0142] To use i MT Achieve Ψ s Decoupling control enables:

[0143] (1+σT r p)L sd i MT -σL sd T r ω s1 i sT =0 (2-12)

[0144] After transformation, we can obtain:

[0145]

[0146] Equation (2-13) is the decoupler module algorithm, which can directly calculate the stator flux linkage vector Ψ from the voltage and current detected on the stator side. s This achieves decoupling.

[0147] In the fifth embodiment of the present invention, air gap magnetic field orientation vector control is adopted. The magnetic field is oriented according to the direction of the torque air gap flux linkage vector, and the real-time torque T is obtained using the following formula. ei :

[0148] T ei =n p Ψ m i sT ;

[0149] Where, np Ψ is the number of pole pairs of the AC asynchronous motor 3. m For air gap flux linkage, i sT This represents the torque component of the stator current.

[0150] In this embodiment, the magnetic field is oriented according to the direction of the air gap flux vector, and its control principle is as follows:

[0151]

[0152] T ei =n p Ψ m i sT (2-15)

[0153]

[0154] In the aforementioned vector control method, the physical parameters determining the torque control accuracy change over long-term operation. Furthermore, the formula for the motor output torque in this control method theoretically ignores factors such as system mechanical friction resistance. Therefore, in one embodiment of the present invention, the control device further includes a torque calibration device 5, detachably connected to the AC asynchronous motor 3 and connected to the logic control module 41, used to calibrate the torque of the AC asynchronous motor 3 to correct the output torque of the valve actuator 4. That is, the present invention can periodically perform on-site torque calibration to eliminate the adverse effects of the aforementioned factors and achieve long-term stability of the system's torque control accuracy. In use, the AC asynchronous motor 3 can be connected to the valve actuator 4. After correctly setting the basic system parameters and performing parameter identification, at least 10 torque values ​​evenly distributed within the range of 10% to 200% of the rated torque of the AC asynchronous motor are selected as detection points. The valve actuator 4 changes the set torque of the AC asynchronous motor 3 point by point according to the calibration logic and drives the AC asynchronous motor 3 to load. Then, the torque calibration device 5 is installed and fixed on the output shaft of the AC asynchronous motor 3 and connected to the valve actuator 4 through a wired signal cable or a wireless communication module. The torque calibration device 5 is used to detect and record the output torque of the AC asynchronous motor 3 corresponding to the set torque at each point. The loading process of each detection point is repeated at least 3 times and the arithmetic average is taken as the output torque detection result of this detection point. The valve actuator 4 statistically analyzes the above detection data, compares the deviation between the set torque and the corresponding output torque, and generates a set of statistical data. Based on the statistical data, a graph or output showing the correspondence between the set torque and the corresponding output torque at each level is generated (the display result can be a graph and curve, and necessary prompts for confirmation) to correct the output torque of the AC asynchronous motor 3. After the relevant corresponding charts are confirmed, the valve actuator 4 can perform corrections to obtain a more accurate output torque during the torque control phase. This embodiment only uses the comparison between the set torque and the corresponding output torque as an example for illustration. See the table below for details. The table below uses an AC asynchronous motor 3 with a rated power of 0.55kW, a rated speed of 1450rpm, and a rated torque of 3.6Nm as an example, showing the relationship between its output torque (i.e., the stall torque at the corresponding detection point) and the set torque. Controlling and correcting the low-speed and stall torque of the AC asynchronous motor 3 allows for accurate sealing pressure during the valve / gate 1 closing process. The stall torque error of the AC asynchronous motor 3 is preferably controlled within ±10% (preferably ±4%) of the rated torque to stably and effectively control the sealing pressure during valve / gate 1 closing. Simultaneously, the discrete detection point data in the statistical table can be integrated into a piecewise function describing the relationship between the set torque and the corresponding output torque (e.g., ...). Figure 11 As shown, the line segments are relatively continuous, with the first and last segments connected, and with different slopes, for querying and use in the torque control process.

[0155] Table 1 Comparison of Set Torque and Corresponding Output Torque

[0156]

[0157]

[0158] The above data describes the relationship between the set torque and the output torque of the AC asynchronous motor 3 using a sufficiently dense, evenly distributed set of feature points. In this embodiment, when the set torque is within the rated torque range (which is also the torque range required for torque control), the error between the set torque and the output torque is within ±10% (preferably ±4%) of the rated torque, showing a good linear relationship; when the set torque exceeds the rated torque, the error increases. The relationship between the set torque and the output torque can be represented by a piecewise linear equation and used to correct the output torque. Because the test results in the corresponding table are discrete data, in actual use, the data between test points are interpolated and supplemented using the line segment equation between adjacent points. For example, when the set torque is between 0.5 and 1.0 Nm, according to... Figure 11 The equation of the relationship curve can be obtained from the starting point (0.5, 0.47) and ending point (1.0, 0.88) of the leftmost line segment:

[0159] y = 0.82x + 0.06;

[0160] Where x is the set torque, and 0.5≤x≤1.0, and y is the measured torque.

[0161] Therefore, piecewise equations can be used to correlate the set torque with the output torque, thereby achieving the goal of accurately controlling the torque by correcting the output value.

[0162] This invention also provides a control method for an electric valve / gate. This control method uses the aforementioned control device to ensure that the valve / gate can "open," "close tightly," and "stop accurately" during its operation. The core of this method is a complete control device and method that uses microprocessor software to drive an AC asynchronous motor to move the valve / gate via vector frequency conversion technology. By collecting real-time torque information from the AC asynchronous motor 3 or the valve / gate 1, and using the set torque of the valve actuator 4 as input and the real-time torque as feedback, a PID control algorithm is used to instantly correct the output torque or output torque limit of the valve actuator 4. This allows for real-time adjustment of the output torque driving the AC asynchronous motor 3, meeting the response speed and control accuracy requirements of each stage of the valve / gate's opening and closing process. This control method allows the logic control module to set corresponding set torques based on the requirements of each stage of the valve / gate 1's opening and closing process. The frequency converter control module controls the frequency converter drive module to drive the AC asynchronous motor 3 to perform the corresponding valve / gate 1 opening or closing action using the set torque as the output torque or an output torque limit. A real-time torque detection unit detects the real-time torque of the AC asynchronous motor 3 or the valve / gate 1. A torque correction unit, based on the real-time torque and the set torque, uses the set torque as input and the real-time torque as feedback, and employs a PID control algorithm to correct the output torque, thereby adjusting the response speed and control accuracy of the output torque in real time according to the real-time torque. The above real-time torque detection and torque correction steps are repeated during the valve / gate 1's opening or closing process until the valve / gate 1 is fully opened or closed, thus achieving closed-loop torque control of the valve / gate 1's opening or closing operation.

[0163] This invention is applicable to the opening and closing control of various valves / gates 1, meeting the control requirements of different working conditions such as sliding doors, swing doors, revolving doors, louvered doors, gate valves, globe valves, ball valves, butterfly valves, plug valves, and dampers. The regulating valve achieves control of different flow characteristics, such as equal percentage control, direct control, fast-opening control, and parabolic control, by precisely adjusting the opening degree or process speed of the valve / gate 1. Each adjustment can be considered a complete working process. For example, during flow adjustment, the ball valve undergoes a working process involving the change in opening and closing angle from 45° to 60°, which includes the starting stage, acceleration stage, constant speed stage, deceleration stage, approach stage, and stopping stage. The switching valve, because it needs to achieve opening and closing actions at a certain speed and ensure sealing when closed, can add a torque control process compared to the regulating valve. For example, the closing process of a gate valve can be divided into the starting stage, acceleration stage, constant speed stage, deceleration stage, slow approach stage, torque control stage, and stopping stage.

[0164] This invention achieves dynamic control of output torque and static correction of set torque by performing torque vector control, on-site torque calibration, and motor parameter identification on the AC asynchronous motor 3. It establishes torque loop, speed loop, and position loop from the inside out using a multi-layered PID nesting method, and selects the closed-loop level or nesting depth according to the needs of different stages of valve / gate 1 execution. This enables full-stroke quasi-servo control of the position, speed, and torque three-loop closed loops of a common AC asynchronous motor 3, ensuring the rapid and precise execution of valve / gate 1, and the accuracy and effectiveness of the execution results. Specifically, it uses an externally nested speed closed loop and position closed loop to nest and control the torque closed loop (such as a current closed loop). This improves the response speed and control accuracy of output torque while also performing speed and position control during the execution stages where running speed and positioning accuracy are required, further enhancing the efficiency, stability, accuracy, and flexibility of the execution process. It can precisely control the sealing pressure of the valve and, based on the load changes throughout the valve's stroke, optimize the matching parameters of speed and torque to achieve precise power control of the ordinary AC asynchronous motor 3, ensuring that the valve / gate is "tightly closed," "accurately stopped," and "smoothly opened." Simultaneously, based on the valve / gate displacement's start-up, acceleration, constant speed, deceleration, slow approach, torque control, and stopping phases, it can achieve phased combined control to meet the requirements of rapid opening and closing, water hammer elimination, regulating valve operating conditions, and fault response. Through short-term "overfrequency" (overspeed) and "overcurrent" (overtorque), a smaller rated AC asynchronous motor 3 can be selected, thereby reducing product size and weight, lowering costs, and improving the dynamic characteristics of the pipeline system. While achieving smooth load control of the ordinary AC asynchronous motor 3, it also reduces the current impact on the power grid.

[0165] 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 control device for an electric valve / gate, comprising an AC asynchronous motor, a transmission device, and a valve actuator, wherein the valve actuator is connected to the AC asynchronous motor, and the AC asynchronous motor is connected to the valve / gate via the transmission device, characterized in that, The valve actuator collects real-time torque information of the AC asynchronous motor or valve / gate operation, and uses the set torque of the valve actuator as input and the real-time torque as feedback. It uses a PID control algorithm to make real-time corrections to the output torque or output torque limit of the valve actuator, so as to adjust the output torque driving the AC asynchronous motor in real time and meet the response speed and control accuracy requirements of each stage of the valve / gate opening and closing process. During the valve / gate opening or closing process, the real-time torque is continuously monitored and the output torque is corrected until the valve / gate is fully opened or closed, so as to achieve closed-loop torque control during the valve / gate opening or closing process; By performing torque vector control, on-site torque calibration, and motor parameter identification on the AC asynchronous motor, dynamic control of the output torque and static correction of the set torque are achieved, respectively. The valve actuator includes a housing and a logic control module, a frequency converter control module, and a frequency converter drive module installed within the housing. The frequency converter drive module is connected to the AC asynchronous motor. The logic control module is connected to the frequency converter drive module through the frequency converter control module. The logic control module adjusts the output torque or output torque limit of the frequency converter drive module in real time through the frequency converter control module. The logic control module includes: The torque setting unit sets the corresponding torque according to the requirements of each stage of the valve / gate opening and closing process; The torque output unit sends the set torque to the variable frequency drive module, and the variable frequency drive module drives the AC asynchronous motor to perform corresponding valve / gate opening or closing actions with the set torque as the output torque or the output torque limit. The real-time torque detection unit acquires the real-time torque of the AC asynchronous motor or valve / gate during operation; and The torque correction unit uses a PID control algorithm to correct the output torque or output torque limit based on the real-time torque and the set torque, and transmits the corrected output torque or output torque limit to the torque output unit. The torque output unit transmits the corrected output torque to the variable frequency drive module through the variable frequency control module, and the variable frequency drive module drives the AC asynchronous motor to respond in real time.

2. The control device for the electric valve / gate as described in claim 1, characterized in that, The logic control module further includes an output current detection unit connected to the real-time torque detection unit. The output current detection unit detects the physical parameters of the AC asynchronous motor and transmits them to the real-time torque detection unit. The real-time torque detection unit calculates the real-time torque and transmits it to the torque correction unit. The physical parameters include stator resistance, rotor resistance, stator-rotor mutual inductance, stator-rotor leakage inductance, and / or no-load current.

3. The control device for the electric valve / gate as described in claim 1, characterized in that, It also includes a torque sensor for acquiring the real-time torque. The torque sensor is installed on the output shaft of the AC asynchronous motor, the output shaft of the valve reduction gearbox, or the valve drive mechanism, and is connected to the real-time torque detection unit or the frequency converter control module to transmit the measured real-time torque signal to the real-time torque detection unit or the frequency converter control module.

4. The control device for the electric valve / gate as described in any one of claims 1-3, characterized in that, It also includes a position sensor, and the logic control module further includes a speed control unit connected to the position sensor. The speed control unit is used to collect the feedback signal from the position sensor to obtain the current speed of the valve, correct the output speed of the AC asynchronous motor through a PID control algorithm, and superimpose the corrected output torque to meet the speed requirements of each stage of valve / gate opening or closing.

5. The control device for the electric valve / gate as described in claim 4, characterized in that, The logic control module also includes a position control unit connected to the position sensor. It is used to determine whether the position nodes of each stage of the valve / gate opening or closing process have been reached based on the feedback signal of the position sensor, and to further adjust the output torque based on the determination result to meet the control logic and stop position accuracy requirements of each stage of the valve / gate opening or closing process.

6. The control device for the electric valve / gate as described in claim 4, characterized in that, The position sensor is a full-stroke sensor and / or a point-position sensor, and the position sensor is installed on the output shaft of the AC asynchronous motor, the output shaft of the gearbox of the transmission device, or the valve drive mechanism.

7. The control device for an electric valve / gate as described in claim 1, 2, 3, 5, or 6, characterized in that, It also includes a torque calibration device, which is detachably connected to the AC asynchronous motor and connected to the logic control module, for calibrating the torque of the AC asynchronous motor to correct the output torque of the valve actuator.

8. A control method for an electric valve / gate, characterized in that, The control device for the electric valve / gate according to any one of claims 1-7 collects real-time torque information of the AC asynchronous motor or valve / gate operation, and uses the set torque of the valve actuator as input and the real-time torque as feedback. It then uses a PID control algorithm to instantly correct the output torque or output torque limit of the valve actuator, thereby adjusting the output torque driving the AC asynchronous motor in real time to meet the response speed and control accuracy requirements of each stage of the valve / gate opening and closing process.

9. An electric valve / gate, characterized in that, The control device for the electric valve / gate as described in any one of claims 1-7.

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