An electrically operated valve / gate and its valve driver

Abstract

An electric valve / gate and a valve driver thereof, the electric valve / gate comprising a valve driver, the valve driver comprising a housing, a core controller and a variable frequency drive module, the core controller meeting valve response speed and control accuracy requirements by adjusting output torque or output torque limit value of the variable frequency drive module in real time, comprising: a logic control unit, setting a corresponding set torque according to valve / gate execution opening and closing process, and sending the set torque to the variable frequency drive module, driving the AC asynchronous motor to execute corresponding valve / gate opening or closing action with the set torque as the output torque or output torque limit value; a real-time torque detection unit, acquiring real-time torque of the AC asynchronous motor or valve / gate operation; and a torque correction unit, correcting the output torque by using a PID control algorithm according to the real-time torque and the set torque, taking the set torque as the input and taking the real-time torque as the feedback to adjust the output torque in real time.

Description

TECHNICAL FIELD

[0001] The present application relates to valve / gate driving technology, in particular to an electric valve / gate and a valve gate driver thereof. BACKGROUND

[0002] Most of the prior art valve / gate electric devices directly start an alternating current asynchronous motor by using a power supply, drive the motor to drive a mechanical transmission mechanism to drive the valve / gate to operate, and achieve the opening and closing of the valve / gate. The alternating current asynchronous motor is widely used in valve / gate electric devices due to its simple structure, reliable operation, light weight, low price, and large starting torque. However, the following problems exist in the use process:

[0003] 1) The torque control precision of the alternating current asynchronous motor is low, and the torque and speed dynamic range is small (the peak torque and speed are limited). In addition, the driving torque of the alternating current asynchronous motor cannot overcome the resistance torque due to the influence of factors such as medium temperature, foreign matter, and corrosion, which causes the valve / gate to not open when opening; the rotating speed of the alternating current asynchronous motor is fixed during the operation of the valve / gate, and the opening and closing speed is constant, which causes the dynamic load of the valve seat to be overloaded when the valve closes to the stop point, resulting in the valve / gate not opening after being closed tightly. The valve / gate of the prior art has the problems of not opening, not closing tightly, and not stopping accurately;

[0004] 2) Real-time position information of the valve / gate cannot be obtained, and full-stroke high-precision position control cannot be achieved;

[0005] 3) The force of the valve seat when the valve is closed to the position cannot be controlled, which easily causes the valve / gate to not close tightly, resulting in internal leakage of the valve / gate; the characteristics change caused by long-term use, aging, and electric parameter drift of the valve / gate, resulting in a large error between the theoretical output value and the actual output value, and the force of the valve seat when the valve is closed to the position is unstable;

[0006] 4) The physical characteristics difference of the alternating current asynchronous motor is not considered, resulting in poor torque, speed, and position control precision, small torque and speed dynamic range, and inconsistent performance of batch products. SUMMARY

[0007] The present application solves the above-mentioned defects of the prior art, and provides an electric valve / gate and a valve gate driver thereof.

[0008] In order to achieve the above-mentioned purpose, the present application provides a valve gate driver, which comprises a shell and a core controller and a variable frequency drive module installed in the shell, the variable frequency drive module is connected with the core controller and an alternating current asynchronous motor respectively, wherein the core controller meets the control requirements of the valve / gate by adjusting the output torque or the output torque limit value of the variable frequency drive module in real time, and the core controller comprises:

[0009] The logic control unit sets a corresponding set torque according to the requirement of valve / gate opening and closing process, and sends the set torque to the variable frequency drive module, and the variable frequency drive module drives the AC asynchronous motor to execute corresponding valve / gate opening or closing action with the set torque as the output torque or output torque limit;

[0010] The real-time torque detection unit obtains the real-time torque of the AC asynchronous motor or valve / gate operation; and

[0011] The torque correction unit corrects the output torque by using PID control algorithm according to the real-time torque and set torque, taking the set torque as input and the real-time torque as feedback, so as to adjust the response speed and control accuracy of the output torque according to the real-time torque.

[0012] The valve driver, wherein the real-time torque is directly obtained by a torque sensor installed on the output shaft of the AC asynchronous motor, the output shaft of the speed reduction transmission box or the driving mechanism, and connected with the real-time torque detection unit to transmit the measured real-time torque signal to the real-time torque detection unit.

[0013] The valve driver, wherein the real-time torque is obtained by an output current detection circuit combined with a vector transformation method, the output current detection circuit detects 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, and the physical parameters include stator resistance, rotor resistance, mutual inductance of stator and rotor, leakage inductance of stator and rotor, and no-load current.

[0014] The valve driver, wherein the three-phase AC signal of the AC asynchronous motor is converted into torque component i sT and excitation component i sM of stator current through coordinate transformation, and the real-time torque is calculated according to different magnetic field orientations, including rotor magnetic field oriented vector control, direct torque control, slip frequency vector control, stator magnetic field oriented vector control or air gap magnetic field oriented vector control;

[0015] The rotor magnetic field oriented vector control performs the magnetic field orientation according to the direction of rotor flux linkage vector, and obtains the real-time torque T ei according to the following formula:

[0016]

[0017] Wherein, n p is the number of motor pole pairs of the AC asynchronous motor, and L mdL represents the equivalent mutual inductance of one phase winding of the AC asynchronous motor when the stator and rotor are coaxial. rd i is the equivalent self-inductance of one phase winding of the rotor of the AC asynchronous motor. sT Ψ is the torque component of the stator current of the AC asynchronous motor. r The rotor flux linkage of the aforementioned AC asynchronous motor;

[0018] The direct torque control obtains the real-time torque T using the following formula. ei :

[0019]

[0020] Where, n p L represents the number of pole pairs of the AC asynchronous motor. m For the mutual inductance between the stator and rotor, L s For the self-inductance of one phase winding of the stator, L r For the self-inductance of one phase winding of the rotor, 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;

[0021] The slip frequency vector control orients the magnetic field based on the slip frequency vector and obtains the real-time torque T using the following formula. ei :

[0022]

[0023] Where, n p T represents the number of pole pairs of the AC asynchronous motor. 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. r ω is the rotor flux linkage of the AC asynchronous motor. s1 This is the slip angular frequency;

[0024] The stator magnetic field orientation vector control orients the magnetic field according to the stator flux linkage vector direction, and obtains the real-time torque T using the following formula. ei :

[0025] T ei =n p Ψ s i sT ;

[0026] Where, n p Ψ is the number of pole pairs of the AC asynchronous motor. sThe stator flux linkage of the AC asynchronous motor, i sT The torque component of the stator current;

[0027] The air-gap magnetic field orientation vector control, the magnetic field orientation is performed according to the torque air-gap flux linkage vector direction, and the real-time torque T is obtained by using the following formula ei :

[0028] T ei = n p Ψ m i sT ;

[0029] Wherein, n p is the motor pole pair number of the AC asynchronous motor, Ψ m is the air-gap flux linkage, i sT is the torque component of the stator current.

[0030] The valve driver, wherein the core controller further comprises:

[0031] A speed control unit is configured to obtain the current speed of the valve by using a vector control method or a feedback signal of a position sensor, correct the output speed of the AC asynchronous motor by a PID control algorithm, and superimpose the corrected output torque with the torque correction unit to correct the output torque so as to meet the speed requirement of each stage of the valve / gate opening or closing.

[0032] The valve driver, wherein the core controller further comprises:

[0033] A position control unit is configured to determine whether the position node of each stage of the valve / gate opening or closing process is reached according to the feedback signal of the position sensor, and further adjust the output torque according to the determination result so as to meet the control logic and the stop position accuracy requirement of each stage of the valve / gate opening or closing.

[0034] The valve driver, wherein the position sensor is a full-stroke sensor and / or a point sensor, so as to realize full-stroke high-precision position control or accurate start / end point position control.

[0035] The valve driver, wherein the position sensor is installed on the output shaft of the AC asynchronous motor, the output shaft of a speed reduction gearbox, or a driving mechanism, and is connected with the core controller.

[0036] The valve driver, wherein the core controller further comprises:

[0037] A torque calibration unit is connected with a torque calibration device, and the torque calibration device is used to calibrate the output torque of the AC asynchronous motor, so as to correct the output torque of the AC asynchronous motor.

[0038] In order to achieve the above-mentioned purpose, the application further provides an electric valve / gate, comprising a valve / gate, a transmission device, an alternating current asynchronous motor connected with the valve / gate through the transmission device, and a valve gate driver connected with the alternating current asynchronous motor and controlling the opening and closing of the valve / gate through the alternating current asynchronous motor, wherein the valve gate driver is the valve gate driver mentioned above, and the valve gate driver and the alternating current asynchronous motor are an integral connection; or the valve gate driver and the alternating current asynchronous motor are separately arranged and connected through a cable or wireless connection.

[0039] The technical effect of the application is that:

[0040] The application can realize the precise control of the torque, speed and position of the ordinary alternating current asynchronous motor through the optimization of the matching parameters of the speed and torque according to the full stroke load change of the on-off valve / gate, so as to ensure that the valve / gate is "closed tightly", "stopped accurately" and "opened quickly"; meanwhile, based on the starting stage, acceleration stage, constant speed stage, deceleration stage, slow approaching stage, torque control stage and stopping stage of the valve / gate displacement, the phased combination control can be realized to meet the requirements of fast opening and closing, water hammer elimination, regulating valve working condition and fault response of the valve / gate; through the short-time "over frequency" (over speed) and "over current" (over torque), the smaller specification alternating current asynchronous motor can be selected compared with the existing valve gate driver, so as to reduce the product volume and weight and lower the cost, and improve the dynamic characteristics of the pipeline system; the load smoothness control of the ordinary alternating current asynchronous motor is improved, and the impact on the power grid is reduced.

[0041] The application will be described in detail below in combination with the drawings and specific embodiments, but not as a limitation to the application. BRIEF DESCRIPTION OF DRAWINGS

[0042] Figure 1 It is a structure schematic diagram of the electric valve / gate of an embodiment of the application;

[0043] Figure 2 It is a structure schematic diagram of the electric valve / gate of another embodiment of the application;

[0044] Figure 3 It is a structure block diagram of the electric valve / gate of an embodiment of the application;

[0045] Figure 4 It is a structure block diagram of the valve gate driver of an embodiment of the application;

[0046] Figure 5 It is a structure block diagram of the valve gate driver of another embodiment of the application;

[0047] Figure 6This is an equivalent circuit diagram for stator resistance identification according to an embodiment of the present invention;

[0048] Figure 7 This is an equivalent circuit of motor T according to an embodiment of the present invention;

[0049] Figure 8 This is an embodiment of the motor anti-Γ equivalent circuit of the present invention;

[0050] Figure 9 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.

[0051] Among them, the attached figures are labeled

[0052] 1 Valve / Gate

[0053] 2. Transmission device

[0054] 21 Gearbox

[0055] 22 Drive mechanism

[0056] 3. AC asynchronous motor

[0057] 4 Valve actuators

[0058] 41 Logic Control Module

[0059] 42 Variable Frequency Control Module

[0060] 43 Variable Frequency Drive Module

[0061] 44 Core Controller

[0062] 45 Signal Conversion Module / IO Module

[0063] 46 Detection and Protection Module

[0064] 47 Temperature Control Module

[0065] 48 Human-Computer Interaction Module

[0066] 5. Torque calibration device

[0067] 6 position sensors

[0068] 7 Torque Sensor

[0069] 8 Power Supply Detailed Implementation

[0070] The structural and working principles of the present invention will be described in detail below with reference to the accompanying drawings:

[0071] 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 The schematic diagram of the electric valve / gate structure of another embodiment of the present application, Figure 3 The block diagram of the electric valve / gate structure of an embodiment of the present application. The electric valve or electric gate of the present application comprises a valve / gate 1, a transmission device 2, an AC asynchronous motor 3 connected with the valve / gate 1 through the transmission device 2, and a valve gate driver 4 connected with a power supply 8 and the AC asynchronous motor 3 respectively and controlling the opening and closing of the valve / gate 1 through the AC asynchronous motor 3. The transmission device 2 can comprise a speed reduction transmission box 21 and a driving mechanism 22. The speed reduction transmission box 21 is connected with the output shaft of the AC asynchronous motor 3 and the input end of the driving mechanism 22 respectively, and the output end of the driving mechanism 22 is connected with the valve / gate 1 to realize the driving of the valve / gate 1. The valve gate driver 4 and the AC asynchronous motor 3 can be an integral connecting piece (see Figure 1 ); or the valve gate driver 4 and the AC asynchronous motor 3 are separately arranged and connected through a cable or wireless connection (see Figure 2 ), that is, the mechanical driving and the electrical driving can be separately arranged to meet the requirements of harsh application environments such as small installation space, high temperature, radiation, high humidity, strong magnetic interference, etc. The composition, structure, mutual positional relationship, connection relationship and working principle of other components of the electric valve / gate of the present application are all mature prior art, and therefore will not be described here. Only the valve gate driver 4 and its working principle of the present application will be described in detail below.

[0072] Referring to Figure 4 and Figure 5 , Figure 4 The block diagram of the valve gate driver 4 of an embodiment of the present application, Figure 5 The block diagram of the valve gate driver 4 of another embodiment of the present application. The valve gate driver 4 of the present application comprises a shell and a core controller 44 and a variable frequency driving module 43 mounted in the shell. The variable frequency driving module 43 is connected with the core controller 44 and the AC asynchronous motor 3 respectively. The core controller 44 adjusts the output torque or the output torque limit value of the variable frequency driving module 43 in real time to meet the response speed and control accuracy requirements of the valve / gate 1. The core controller 44 is preferably a single-chip microcomputer and a DSP, and can be specifically equipped with a logic processor, an IO system, an internal bus, etc. The variable frequency driving module 43 is a basic module of vector frequency conversion control, and can be equipped with a digital signal processor, a power conversion circuit, a power driving circuit, etc. For example, Figure 4 and Figure 5As shown, the valve driver 4 can also include a wireless communication module, a detection and protection module 46, an IO module, a human-computer interaction module 48, a field bus module, a measurement conversion module, a temperature control module 47, a power supply battery and a cable connection plug, etc. The wireless communication module is used for connection and information exchange with a remote controller and an external portable device, and can include an infrared transceiver circuit, a Bluetooth communication circuit, etc., and interfaces for infrared communication, Bluetooth communication, serial bus communication, Ethernet communication, etc., which can satisfy wired or wireless connection of the valve driver 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, inversion and other electric energy conversion when driving the AC asynchronous motor 3, and can include a rectification circuit, a direct current circuit, an inversion circuit, a detection circuit, etc. The IO module is used for connection, conversion and protection of input and output signals, and can include an IO power supply circuit, a digital input circuit, a digital output circuit, an analog input circuit, an analog output circuit, etc. The human-computer interaction module 48 is used for parameter and instruction input and display of running state and alarm information, and can include a display screen and a button panel, etc. The field bus module is used for information exchange with a host computer and external monitoring equipment, and can include a Modbus bus, a CAN bus, etc. The measurement conversion module is used for converting sinusoidal voltage signals, TTL rectangular wave signals and HTL rectangular wave signals collected by the encoder to collect valve / gate displacement information into collector open circuit signals and feeding back to the logic control module 41, and can include a signal conversion circuit, a high-speed counting circuit, etc. The temperature control module 47 is used for whole machine temperature control, and can include a temperature sensor, a cooling fan, an aluminum heat sink, etc. The valve driver 4 can be used for all action control, information display, alarm and protection of the on-off valve / gate 1.

[0073] The core controller 44 of the embodiment includes a logic control unit configured to set a corresponding set torque according to a requirement of each stage of the opening and closing process of the valve / gate 1, and send the set torque to the variable frequency drive module 43, the variable frequency drive module 43 drives the AC asynchronous motor 3 to perform a corresponding valve / gate 1 opening or closing action with the set torque as an output torque or an output torque limit value; a real-time torque detection unit configured to acquire a real-time torque of the AC asynchronous motor 3 or the valve / gate 1; and a torque correction unit configured to correct the output torque by using a PID control algorithm with the set torque as an input and the real-time torque as a feedback according to the real-time torque and the set torque, and send the corrected output torque to the variable frequency drive module 43, so as to adjust a response speed and control accuracy of the output torque according to the real-time torque.

[0074] In Figure 4In the illustrated embodiment, the core controller 44 can be divided into a logic control module 41 and a frequency conversion control module 42. The logic control module 41 is connected to the frequency conversion drive module 43 through the frequency conversion control module 42. The aforementioned logic control unit, real-time torque detection unit, and torque correction unit can all be integrated into either the logic control module 41 or the frequency conversion control module 42. The logic control module 41 can be used for overall machine logic control, storing and executing control programs. The logic control module 41 can be a microcontroller, DSP, PLC, etc., and may include program memory, data memory, central processing unit (CPU), I / O interface, internal bus, etc. The frequency conversion control module 42 can be built from a microcontroller or DSP chip and peripheral circuits, used to generate motor characteristic parameters and torque vector control algorithms, driving the AC asynchronous motor 3 in conjunction with the inverter circuit. It may include program memory, data memory, central processing unit (CPU), I / O interface, internal bus, etc.

[0075] exist Figure 5 In this embodiment, the logic control module 41 and the frequency conversion control module 42 can be integrated into the core controller 44. The core controller 44 and the frequency conversion drive module 43 can also be integrated into one unit. 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 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 it can realize the function of real-time adjustment of the output torque or output torque limit of the frequency conversion drive module 43 to meet the response speed and control accuracy requirements of the valve / gate 1.

[0076] Figure 5 In the embodiment shown, the real-time torque can be directly obtained by the torque sensor 7. The torque sensor 7 can be installed on the output shaft of the AC asynchronous motor 3, the output shaft of the reduction gearbox 21, or the input or output shaft of the drive mechanism 22, and connected to the real-time torque detection unit to transmit the real-time torque signal it measures to the real-time torque detection unit for torque correction.

[0077] Figure 4In the embodiment shown, the real-time torque is preferably obtained by an output current detection circuit combined with a vector transformation method. The output current detection circuit detects physical parameters of the asynchronous motor 3 and transmits them to the real-time torque detection unit. The real-time torque detection unit obtains the real-time torque by calculation and transmits it to the torque correction unit. The physical parameters can include stator resistance, rotor resistance, stator-rotor mutual inductance, stator-rotor leakage inductance, and no-load current. The three-phase alternating current signal of the asynchronous motor 3 can be converted into a torque component isT of the stator current and an excitation component isM of the stator current through coordinate transformation, and the real-time torque can be obtained according to different field orientations by using rotor field orientation vector control, direct torque control, slip frequency vector control, stator field orientation vector control, or air gap field orientation vector control. That is, the vector torque control is used as the output method, the detection results of the torque detection circuit (preferably the output current detection circuit in this embodiment) are used as the feedback signal, the output torque is controlled and corrected through PID closed-loop adjustment, so that the actual output torque of the valve / gate 1 during operation is within the range of the set torque (i.e., the expected value).

[0078] To more accurately realize vector control, the valve / gate driver 4 can also identify the physical parameters of the asynchronous motor 3 in advance. First, the parameters of the asynchronous motor 3, such as stator resistance, rotor resistance, stator-rotor mutual inductance, and stator-rotor leakage inductance, are collected to ensure the accuracy of the basic parameters in torque vector control. That is, the core controller 44 can also include a physical parameter identification unit for obtaining the physical parameters of the asynchronous motor 3 to more accurately control the torque vector of the asynchronous motor 3. AC and DC excitation signals can be input to the asynchronous motor 3, and the stator current feedback is monitored in real time. The above-mentioned related parameters are calculated according to the values and phase relationships of the voltage and current. The no-load current is used to estimate the torque consumption (such as friction, ventilation, core loss, etc.) during the operation of the asynchronous motor 3 and compensate for the output torque. The no-load current is preferably 20% to 50% of the rated current of the motor.

[0079] In this embodiment, the output current detection circuit in the core controller 44 is used for parameter detection. The real-time torque (which can be calculated by the rotor equivalent self-inductance, rotor equivalent mutual inductance, rotor flux, and stator current torque component) is collected as the feedback, and the PID control principle is used for closed-loop control and correction of the output torque. Finally, torque vector control is realized to ensure the torque response speed and control accuracy during the operation of the valve / gate 1. The stator resistance in this embodiment can be obtained as follows:

[0080] The control inverter power supply outputs a single-phase DC voltage. At this time, the motor circuit diagram in this case can be simplified as shown in Figure 6

[0081] ​

[0082] wherein V dc = DC voltage, i U = stator current, R1 = stator resistance.

[0083] Due to the influence of the voltage drop of the switch tube, the voltage actually applied to the stator will produce a certain error. In order to eliminate the error, different voltage signals can be applied multiple times, and the slope of the stator voltage and the stator current is taken as the stator resistance.

[0084]

[0085] The rotor resistance, the stator-rotor mutual inductance and the stator-rotor leakage inductance of the embodiment can be obtained in the following way:

[0086] The electromagnetic phenomenon of the alternating current asynchronous motor 3 under the excitation of a single-phase sinusoidal signal is basically the same as that under the excitation of a three-phase sinusoidal signal. Through this method, the motor torque at this time is zero, and the motor remains stationary. At this time, the equivalent circuit of the motor can be replaced by a three-phase equivalent circuit.

[0087] The vector equation of the stator and rotor of the alternating current asynchronous motor 3 is:

[0088]

[0089] wherein, p is a differential operator, R1 is a stator resistance, R r is a rotor resistance, L sσ is a stator leakage inductance, L rσ is a rotor leakage inductance, L m is a stator-rotor mutual inductance, ω is a rotor speed, and the cage rotor

[0090] The output W phase is disconnected, and the U phase and the V phase are controlled according to the H-bridge type sinusoidal voltage modulation signal to control the on-off of the inverter, so as to generate a sinusoidal voltage excitation signal. The sinusoidal voltages of the U phase and the V phase are set as The phase voltage and the phase current in the alternating current asynchronous motor 3 satisfy the following relationship:

[0091]

[0092]

[0093] wherein V Un , V Vn , V wn are the U phase, the V phase and the W phase midpoint voltages, respectively.

[0094] At this time, the motor torque is 0, and the T-type equivalent circuit diagram of the motor at this time is shown in Figure 7. In general cases, the stator leakage inductance is the same as the rotor leakage inductance, i.e. L sσ = L rσ . Figure 8 The motor inverse Γ equivalent circuit diagram is an equivalent circuit after T is changed, and the relationship of the circuit parameters of the changed T-type equivalent circuit is as follows:

[0095]

[0096]

[0097]

[0098] It can be obtained from the figure that:

[0099]

[0100]

[0101] In the above formula, is the initial phase of the voltage, is the initial phase of the current.

[0102] It can be obtained from formula (1-6) to formula (1-9) that:

[0103]

[0104] The expression of the impedance can be obtained through the inverse Γ equivalent circuit as follows:

[0105]

[0106] The single-phase motor test is performed on the alternating current asynchronous motor 3 by applying the sinusoidal voltage signals with frequencies of f1 and f2 respectively, the equivalent impedance of the stator current is detected, and R, (f) = R-R1. The calculation formula of the motor parameters under the inverse Γ equivalent circuit can be obtained from formula (1-12)

[0107]

[0108]

[0109]

[0110] According to the relationship formula (1-5) of the parameter conversion of the T-type equivalent circuit and the inverse Γ equivalent circuit, the calculation formula of the motor rotor resistance, the stator-rotor mutual inductance and the stator-rotor leakage inductance can be obtained as follows:

[0111]

[0112]

[0113] L sσ = L rσ = L` sσ + L` m - L m (1-18)

[0114] In an embodiment of the present application, the rotor magnetic field orientation vector control is preferably adopted, the magnetic field orientation is performed according to the rotor total flux vector direction, and the real-time torque T is obtained by using the following formula ei :

[0115]

[0116] wherein n p is the motor pole pair number of the AC asynchronous motor 3, L md is the equivalent mutual inductance of one phase winding when the stator and rotor of the AC asynchronous motor 3 are coaxial, L rd is the equivalent self-inductance of one phase winding of the rotor of the AC asynchronous motor 3, i sT is the torque component of the stator current of the AC asynchronous motor 3, Ψ r is the rotor flux of the AC asynchronous motor 3.

[0117] The control principle is as follows:

[0118]

[0119]

[0120]

[0121] wherein Ψ rM is the M-axis component of the rotor total flux; Ψ rT is the T-axis component of the rotor total flux; i rM is the M-axis component of the rotor current; i rT is the T-axis component of the rotor current; n p is the motor pole pair number; is the equivalent self-inductance of one phase winding of the rotor; is the equivalent mutual inductance of one phase winding when the stator and rotor are coaxial; i sT is the torque component of the stator current; Ψ r is the rotor flux; is the rotor electromagnetic time constant; p is the differential operator; i sM is the excitation component of the stator current.

[0122] In another embodiment of the present application, the direct torque control can also be adopted, and the real-time torque T is obtained by using the following formulaei :

[0123]

[0124] wherein n p is the number of pole pairs of the AC asynchronous motor 3, L m is the mutual inductance of the stator and rotor, L s is the self-inductance of the stator one-phase winding, L r is the self-inductance of the rotor one-phase winding, Ψ s is the stator flux linkage, Ψ r is the rotor flux linkage, θ sr is the torque angle, which is the angle between the vectors Ψ s and Ψ r .

[0125] The direct torque control is based on the mathematical model of the stator shaft system and uses the space vector analysis method to realize motor control, and the control principle is as follows:

[0126] Stator flux equation:

[0127]

[0128] wherein u s is the stator shaft system voltage vector.

[0129] Neglecting the stator resistance voltage drop R s i s , we have:

[0130] Ψ≈∫u s dt (2-18)

[0131] The torque equation is:

[0132]

[0133] θ sr is the torque angle, which is the angle between the vectors Ψ s and Ψ r .

[0134] In the third embodiment of the present application, slip frequency vector control can be used, the magnetic field orientation is performed according to the slip frequency vector, and the real-time torque T ei is obtained by the following formula:

[0135]

[0136] wherein n p is the number of pole pairs of the AC asynchronous motor 3, T r is the rotor electromagnetic time constant, L rdΨ 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.

[0137] Slip frequency vector control can be performed based on rotor magnetic field fixed vector control, and its control principle is as follows:

[0138]

[0139]

[0140] Where, ω s1 This is the slip angular frequency.

[0141] 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 :

[0142] T ei =n p Ψ s i sT ;

[0143] 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.

[0144] In this embodiment, the magnetic field is oriented according to the direction of the stator flux linkage vector, and its control principle is as follows:

[0145]

[0146] T ei =n p Ψ s i sT (2-7)

[0147]

[0148] Among them, Ψ s For stator flux linkage; Ψ sM The stator 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:

[0149]

[0150]

[0151] 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:

[0152]

[0153] To use i MT Achieve Ψ s Decoupling control enables:

[0154] (1+σT r p)L sd i MT -σL sd T r ω s1 i sT =0 (2-12)

[0155] After transformation, we can obtain:

[0156]

[0157] 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.

[0158] 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 :

[0159] T ei =n p Ψ m i sT ;

[0160] Where, n p 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.

[0161] 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:

[0162]

[0163] Tei = n p Ψ m i sT (2-15)

[0164]

[0165] The physical parameters that determine the torque control accuracy in the above vector control method will change over time, and the formula for motor output torque in the above control method theoretically ignores factors such as system mechanical friction resistance. Therefore, in an embodiment of the present application, the core controller 44 can further include:

[0166] Torque calibration unit, connected with torque calibration device 5, through the torque calibration device 5 to the asynchronous motor 3 for torque calibration, for correcting the output torque of the asynchronous motor 3. That is, the present application can regularly use the calibration of torque to eliminate the adverse effects of the above factors, to achieve long-term stability of the system torque control precision. The asynchronous motor 3 can be connected with the valve driver 4, the correct setting of the system parameters and the execution of parameter identification, in the range of 10% ~ 200% of the asynchronous motor rated torque to select the evenly distributed not less than 10 torque value as the detection point, the valve driver 4 according to the calibration logic point by point change the set torque of the asynchronous motor 3 and drive the asynchronous motor 3 load, load cover 0 to the maximum output torque of the asynchronous motor 3; then the torque calibration device 5 is installed and fixed on the output shaft of the asynchronous motor 3, and is connected with the valve driver 4 through the wired signal cable or wireless communication module, and the torque calibration device 5 is used to detect the output torque of the asynchronous motor 3 corresponding to each point of the set torque and record; repeat the above each detection point loading process not less than 3 times and take the arithmetic mean as the output torque detection result of this detection point; and the valve driver 4 statistics and analysis of the above test data, compare the set torque and the corresponding output torque deviation and generate a complete set of statistical data, according to the statistical data to generate the corresponding relationship chart of each level of the set torque and the corresponding output torque display or output (the display result can be chart and curve, and the necessary prompt information for confirmation), for correcting the output torque of the asynchronous motor 3. After the relevant corresponding chart is confirmed, the valve driver 4 can execute the correction to obtain more accurate output torque of the torque control stage. The present embodiment is only described by taking the set torque and the corresponding output torque as an example, and the specific can be seen from the following table, which is an example of the asynchronous motor 3 with rated power 0.55kW, rated speed 1450rpm and rated torque 3.6Nm. The relationship between the output torque (i.e. the corresponding detection point of the locked rotor torque) and the set torque. Among them, the low speed and locked rotor torque of the control and correction of the asynchronous motor 3 can make the valve 1 obtain accurate sealing specific pressure in the closing process, and the locked rotor torque error of the asynchronous motor 3 is preferably controlled within ±10% (preferably ±4%) of the rated torque, so as to stably and effectively control the sealing specific pressure of the valve 1 in the closing process. At the same time, the discrete detection point data in the statistical table can also be integrated into a segmented function (such as Figure 9 the relative continuous, the first joint, the slope of the broken line segment) describing the relationship between the set torque and the corresponding output torque, for torque control process query and use.

[0167] Table 1 set torque and corresponding output torque comparison table

[0168]

[0169]

[0170] The above data describes the relationship between the set torque and 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 output torque is within ±10% (preferably ±4%), showing a good linear relationship; when the set torque exceeds the rated torque, the error increases. The relationship between the set torque and 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 9 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:

[0171] y = 0.82x + 0.06;

[0172] Where x is the set torque, and 0.5≤x≤1.0, and y is the output torque.

[0173] 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.

[0174] To further improve control accuracy, in one embodiment of the present invention, the core controller 44 may further include: a speed control unit, used to obtain the current speed of the valve by means of current detection combined with vector transformation or feedback signal from position sensor 6, correct the output speed of AC asynchronous motor 3 by means of PID control algorithm, and further correct the output torque by superimposing the calculation result of the torque correction unit, so as to meet the speed requirements of each stage of opening or closing of valve / gate 1.

[0175] In another embodiment of the present application, the core controller 44 can further comprise a position control unit for determining whether a position node of each stage of the opening or closing process of the valve / gate 1 is reached according to the feedback signal of the position sensor 6, and further adjusting the output torque according to the feedback results of the speed control unit and the torque correction unit to meet the requirements of the control logic and the stopping position accuracy of each stage of the opening or closing process of the valve / gate 1. In this embodiment, the position, speed, and torque of the valve / gate 1 can be monitored in real time, and the nested control mode of the torque loop, speed loop, and position loop can be used from the inside to the outside according to the nested relationship, wherein the torque loop directly affects the torque, has fast response and high accuracy, and can meet the requirements of real-time control of the motor output torque; the speed loop works on the basis of the torque loop, obtains the current speed of the valve / gate 1 through the feedback of the valve actuator 4 or the position sensor 6 by the basic principle of vector control, and exerts an influence through the torque loop to meet the requirements of different stages on the speed; 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 layer of adjustment, which adjusts the output according to the feedback of the valve actuator 4 or the position sensor 6 to meet the requirements of the control logic and the stopping position accuracy.

[0176] The position sensor 6 can be a full-stroke sensor and / or a point sensor to achieve full-stroke high-precision position control or accurate start / endpoint position control. The position sensor 6 can be installed on the output shaft of the alternating current asynchronous motor 3, the output shaft of the speed reduction transmission box 21, or the input shaft or output shaft of the driving mechanism 22, and is connected with the core controller through a signal conversion module / IO module 45. The present application is compatible with full-stroke sensors and point sensors, and is suitable for full-stroke sensors, point sensors, combinations of full-stroke sensors and point sensors 6. In practice, the selection of the position sensor 6 is related to the type of the valve / gate 1, the mechanical structure characteristics of the valve / gate 1, the use environment of the valve / gate 1, and the production technical level of the valve / gate 1, etc., and generally does not change due to the needs of the valve actuator 4. In a system pre-installed with a full-stroke sensor, different stages (which can include a starting stage, an acceleration stage, a constant speed stage, a deceleration stage, a slow approach stage, a torque control stage, and a stopping stage, etc.) performed by the valve / gate 1 are accurately divided according to the continuous position signal, and the parameters such as the starting position, the ending position, the speed, the torque, the acceleration, and the deceleration of each process are reasonably controlled to achieve the expected execution effect. The present application can adapt to various types of full-stroke sensors with different interface conversion hardware.

[0177] Among them, the node point sensor is still in a certain proportion in the valve execution system because of low cost, easy installation and strong environmental adaptability. In the system pre-installed with node point sensor, different processes of valve execution are identified and divided according to discrete node position signals, and the execution results of opening or closing are ensured under the premise of ensuring safety. In the system pre-installed with full stroke sensor and point position sensor 6, the node point sensor is used as a protector or safety redundancy device to protect the limit or special position in the same way as the system pre-installed with full stroke sensor only. The compatibility of the sensor type and form of the application widens its application range and applicable environment, and improves the safety of the applicable process.

[0178] The valve driver 4 of the application can be applied to the opening and closing control of various valves / gates 1, and meets the control requirements of different working conditions such as sliding door, swing door, rotating door, louver door, gate valve, stop valve, ball valve, butterfly valve, plug valve, air valve, etc. Among them, the regulating valve adjusts the opening size or process movement speed of the valve / gate 1 to realize the control of different flow characteristics, such as equal percentage control characteristic, direct control characteristic, quick opening control characteristic and parabolic control characteristic. The positioning of any position in the regulating valve can be regarded as a complete working process. For example, the working process experienced by the ball valve in the process of changing the opening and closing angle from 45° to 60° during flow adjustment is the starting stage, acceleration stage, uniform speed stage, deceleration stage, approaching stage and stopping stage. The on-off valve needs to realize the opening and closing action at a certain speed, and needs to ensure the sealing when closed, so it can increase the torque control process compared with the regulating valve. For example, the closing process of the gate valve can be divided into starting stage, acceleration stage, uniform speed stage, deceleration stage, slow approaching stage, torque control stage and stopping stage.

[0179] The application can realize dynamic control of output torque and static correction of set torque by torque vector control, torque calibration and motor parameter identification of the valve driver 4 on the AC asynchronous motor 3. Torque loop, speed loop and position loop are respectively established from inside to outside by multiple PID nesting, and closed loop level or nesting depth is selected according to the requirements of different stages of the valve / gate 1 execution process, so as to realize three-closed-loop full-stroke quasi servo control of the ordinary AC asynchronous motor 3, thereby ensuring the rapid and accurate execution process of the valve / gate 1 and the accurate and effective execution result. That is, the method of nesting control of the torque closed loop (such as current closed loop) by the externally nested speed closed loop and position closed loop can improve the response speed and control accuracy of the output torque, and also control the speed and position in the execution stage to ensure the running speed and positioning accuracy, thereby further improving the efficiency, stability, accuracy and flexibility of the execution process. The valve sealing specific pressure can be accurately controlled, the matching parameters of the speed and torque can be optimized according to the full-stroke load change of the on-off valve, the power of the ordinary AC asynchronous motor 3 can be accurately controlled, and the valve / gate can be closed tightly, stopped accurately and opened accurately. Meanwhile, based on the starting stage, acceleration stage, constant speed stage, deceleration stage, slow approaching stage, torque control stage and stopping stage of the valve / gate displacement, the phased combination control can be realized, different control strategies can be matched according to different working conditions of the valve / gate in the use field, such as efficiency(time) priority of the on / off valve, position accuracy priority of the on / off valve, torque accuracy priority of the on / off valve, valve safety priority of the on / off valve, pipeline safety priority of the on / off valve and pipeline system stability priority of the on / off valve, so as to meet the requirements of fast opening and closing, water hammer elimination, regulating valve working condition and fault response. By short-time "over frequency" (over speed) and "over current" (over torque), a smaller size AC asynchronous motor 3 can be selected, thereby reducing the product size and weight and reducing the cost, and improving the dynamic characteristics of the pipeline system. The load smoothness control of the ordinary AC asynchronous motor 3 can be realized, and the impact on the power grid can be reduced.

[0180] Of course, the application can have other various embodiments, and those skilled in the art can make various corresponding changes and modifications according to the application without departing from the spirit and essence of the application. However, these corresponding changes and modifications should belong to the protection scope of the claims attached to the application.

Claims

1. A valve drive comprising a housing and a core controller and a variable frequency drive module mounted within the housing, the variable frequency drive module being connected to the core controller and an alternating current asynchronous motor, respectively, characterized in that, The core controller meets the valve / gate response speed and control accuracy requirements by adjusting the output torque or output torque limit value of the variable frequency drive module in real time, and the core controller comprises: A logic control unit sets a corresponding set torque according to the requirements of each stage of the valve / gate opening and closing process, and sends the set torque to the variable frequency drive module, and the variable frequency drive module drives the AC asynchronous motor to perform a corresponding valve / gate opening or closing action with the set torque as the output torque or output torque limit value; A real-time torque detection unit acquires real-time torque of the AC asynchronous motor or valve / gate operation; and A torque correction unit corrects the output torque by using a PID control algorithm according to the real-time torque and the set torque, taking the set torque as the input and the real-time torque as the feedback, so as to adjust the response speed and control accuracy of the output torque according to the real-time torque. Wherein, the real-time torque is acquired by an output current detection circuit combined with a vector transformation method, the output current detection circuit detects physical parameters of the AC asynchronous motor and transmits them to the real-time torque detection unit, and the real-time torque detection unit calculates and acquires the real-time torque and transmits it to the torque correction unit; The three-phase alternating current signal of the alternating current asynchronous motor is converted into torque component i of stator current through coordinate transformation sT and excitation component i of stator current sM According to different magnetic field orientations, the real-time torque is calculated by using 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 respectively. Wherein, the rotor magnetic field orientation vector control, according to the rotor full magnetic chain vector direction carries out the magnetic field orientation, and obtains the real-time torque T by using the following formula ei : wherein n p is the number of pole pairs of the AC asynchronous motor, L md is the equivalent mutual inductance of a phase winding of the AC asynchronous motor when the stator and the rotor are coaxial, L rd is the equivalent self-inductance of a phase winding of the rotor of the AC asynchronous motor, i sT is the torque component of the stator current of the AC asynchronous motor, Ψ r is the rotor flux of the AC asynchronous motor; The direct torque control obtains the real-time torque T using the following formula ei : wherein n p is the number of pole pairs of the AC asynchronous motor, L m is the mutual inductance between the stator and the rotor, L s is the self-inductance of the stator phase winding, L r is the self-inductance of the rotor phase winding, Ψ s is the stator flux linkage, Ψ R is the rotor flux linkage, θ sr is the torque angle, being the angle between the vectors Ψ s and Ψ r . The slip frequency vector control performs the magnetic field orientation according to the slip frequency vector, and acquires the real-time torque by using the following formula: wherein n p is the number of pole pairs of the AC asynchronous motor, T r is the rotor electromagnetic time constant, L rd is the equivalent self-inductance of a phase winding of the rotor of the AC asynchronous motor, Ψ r is the rotor flux of the AC asynchronous motor, ω s1 is the slip angular frequency; The stator magnetic field orientation vector control carries out the magnetic field orientation according to the stator flux linkage vector direction, and obtains the real-time torque T by using the following formula ei : T ei = n p Ψ s i sT ; wherein n p is the number of pole pairs of the AC asynchronous motor, Ψ s is the stator flux of the AC asynchronous motor, i sT is the torque component of the stator current; The air-gap magnetic field orientation vector control, according to the torque air-gap flux vector direction, carries out the magnetic field orientation, and obtains the real-time torque T by using the following formula ei : T ei = n p Ψ m i sT ; where n p is the number of pole pairs of the AC asynchronous motor, Ψ m is the air-gap flux, i sT is the torque component of the stator current.

2. The valve actuator of claim 1, wherein The real-time torque is directly acquired by a torque sensor, the torque sensor is installed on an output shaft of the AC asynchronous motor, an output shaft of a speed reduction transmission box or a driving mechanism, and is connected with the real-time torque detection unit to transmit the measured real-time torque signal to the real-time torque detection unit.

3. The valve actuator of claim 1, wherein The physical parameters include stator resistance, rotor resistance, stator-rotor mutual inductance, stator-rotor leakage inductance and no-load current.

4. The valve actuator of any of claims 1-3, wherein, The core controller further comprises: A speed control unit is used to acquire the current speed of the valve by using a vector control method or a feedback signal of a position sensor, correct the output speed of the AC asynchronous motor by a PID control algorithm, and superimpose the correction of the output torque with the torque correction unit to correct the output torque, so as to meet the speed requirements of each stage of the valve / gate opening or closing.

5. The valve actuator of claim 4, wherein the valve actuator is configured to operate the valve in the first direction when the valve actuator is in the first position and the second position. The core controller further comprises: A position control unit is used to determine whether the position node of each stage of the valve / gate opening or closing process is reached according to the feedback signal of the position sensor, and further adjust the output torque according to the determination result, so as to meet the control logic and stop position accuracy requirements of each stage of the valve / gate opening or closing.

6. The valve actuator of claim 5, wherein the valve actuator is configured to operate the valve in the first direction when the valve actuator is in the first position and the second position. The position sensor is a full-stroke sensor and / or a point-type sensor to realize full-stroke high-precision position control or accurate start / end point position control.

7. The valve actuator of claim 6 wherein, The position sensor is installed on an output shaft of the AC asynchronous motor, an output shaft of a speed reduction transmission box or a driving mechanism, and is connected with the core controller.

8. The valve actuator of claims 1, 2, 3, 5, 6, or 7, wherein, The core controller further comprises: A torque calibration unit is connected with a torque calibration device, and calibrates the output torque of the AC asynchronous motor by the torque calibration device for correcting the output torque of the AC asynchronous motor.

9. An electrically operated valve / gate comprising a valve / gate, a transmission, an alternating current asynchronous motor connected to the valve / gate through the transmission, and a valve drive connected to the alternating current asynchronous motor and controlling opening and closing of the valve / gate through the alternating current asynchronous motor, characterized in that, The valve driver is the valve driver of any one of claims 1-8, which is integrally connected with the AC asynchronous motor; or the valve driver is separately arranged with the AC asynchronous motor and connected through a cable or wireless connection.

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