WO2023174357A1

WO2023174357A1 - Electric valve/gate and valve driver thereof

Info

Publication number: WO2023174357A1
Application number: PCT/CN2023/081801
Authority: WO
Inventors: 周文; 赵战国; 张大鹏; 赵刚; 郑璐明; 王泽平; 王晓江
Original assignee: 北京雷蒙赛博核装备技术研究有限公司
Priority date: 2022-03-17
Filing date: 2023-03-16
Publication date: 2023-09-21
Also published as: CN116792550A

Abstract

An electric valve/gate and a valve driver thereof, the electric valve/gate comprising the valve driver. The valve driver comprises a housing, a core controller, and a variable-frequency drive module. The core controller adjusts an output torque or an output torque limit of the variable-frequency drive module in real time, so as to meet valve response speed and a control accuracy requirements, and comprises: a logic control unit, setting a corresponding set torque according to an opening and closing process of a valve/gate, and sending the set torque to the variable-frequency drive module, so as to drive an alternating-current asynchronous motor using the set torque as the output torque or the output torque limit, execute a corresponding valve/gate opening or closing action; a real-time torque detection unit, acquiring a real-time running torque of the alternating-current asynchronous motor or the valve/gate; and a torque correction unit, correcting the output torque using a PID control algorithm according to the real-time torque and the set torque, i.e., using the set torque as an input and using the real-time torque as a feedback, so as to immediately adjust the output torque.

Description

An electric valve/door and its valve driver

Technical field

The present invention relates to valve/gate driving technology, in particular to an electric valve/gate and its valve driver.

Background technique

Most of the valve/door electric devices in the existing technology use the power supply to directly start the AC asynchronous motor, and use the driver to control the motor to drive the mechanical transmission mechanism to drive the valve/door to open/close the valve. AC asynchronous motors are widely used in valve/gate electric devices due to their simple structure, reliable operation, light weight, cheap price and large starting torque. However, there are the following problems during use:

1) The torque control accuracy of AC asynchronous motors is low, the dynamic range of torque and speed is small (peak torque and speed are limited), coupled with the influence of factors such as medium temperature, foreign matter, rust, etc., the driving torque of AC asynchronous motors cannot overcome the resistance torque, resulting in The valve/door cannot be opened when the valve is opened; during the operation of the valve/door, the rotation speed of the AC asynchronous motor is fixed, and the valve opening/closing speed remains unchanged. When the valve is closed and reaches the end point, the dynamic load of the valve seat is overloaded, causing the valve/door to open. The door cannot be opened after it is tightly closed. The existing valves/doors have problems such as "not opening", "not closing tightly", and "not stopping accurately";

2) The real-time position information of the valve/door cannot be obtained, and high-precision position control of the full stroke cannot be achieved;

3) Unable to control the force on the valve seat when the valve is closed in place, which may easily cause the valve/door to not close tightly, leading to internal leakage of the valve/door; the valve/door's characteristics will change due to wear, aging, electrical parameter drift, etc. during long-term use. , 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 closed is unstable;

4) The differences in physical characteristics of AC asynchronous motors are not considered, resulting in poor torque, speed, and position control accuracy, small dynamic ranges of torque and speed, and inconsistent performance of batch products.

Contents of the invention

The technical problem to be solved by the present invention is to provide an electric valve/gate and its valve driver in view of the above-mentioned defects of the prior art.

In order to achieve the above object, the present invention provides a valve driver, which includes a housing, a core controller and a variable frequency drive module installed in the housing. The variable frequency drive module is connected to the core control module respectively. The controller is connected to an AC asynchronous motor, wherein the core controller meets the control requirements of the valve/door by adjusting the output torque or output torque limit of the variable frequency drive module in real time. The core controller includes:

The logic control unit sets the corresponding set torque according to the requirements of each stage of the valve/door opening and closing process, and sends the set torque to the variable frequency drive module. The variable frequency drive module uses the set The torque is the output torque or the output torque limit drives the AC asynchronous motor to perform the corresponding valve/gate opening or closing action;

A real-time torque detection unit to obtain the real-time torque of the AC asynchronous motor or valve/gate operation; and

A torque correction unit, based on the real-time torque and the set torque, using the set torque as input, using the real-time torque as feedback, and using a PID control algorithm to correct the output torque to adjust according to the real-time torque The response speed and control accuracy of the output torque.

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

The above-mentioned valve driver, wherein the real-time torque is obtained through an output current detection circuit combined with a vector transformation method. The output current detection circuit 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 The torque detection unit calculates and obtains the real-time torque and transmits it to the torque correction unit. The physical parameters include stator resistance, rotor resistance, stator and rotor mutual inductance, stator and rotor leakage inductance and no-load current.

The above valve driver, wherein the three-phase AC signal of the AC asynchronous motor is converted into the torque component i _sT of the stator current and the excitation component i _sM of the stator current through coordinate transformation, and the rotor magnetic field orientation vector is respectively used according to the different magnetic field orientations. Control, direct torque control, slip frequency vector control, stator magnetic field oriented vector control or air gap magnetic field oriented vector control calculation to obtain the real-time torque;

Among them, the rotor magnetic field orientation vector control performs the magnetic field orientation according to the direction of the rotor full flux vector, and uses the following formula to obtain the real-time torque _Tei :

Among them, n _p is the number of motor pole pairs of the AC asynchronous motor, and L _md is the AC asynchronous motor. The equivalent mutual inductance of one-phase winding when the stator and rotor of the motor are coaxial, L _rd is the equivalent self-inductance of the one-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 linkage of the AC asynchronous motor;

The direct torque control uses the following formula to obtain the real-time torque _Tei :

Among them, n _p is the number of motor pole pairs of the AC asynchronous motor, L _m is the stator and rotor mutual inductance, L _s is the self-inductance of the stator one-phase winding, L _r is the self-inductance of the rotor one-phase winding, and Ψ _s is the stator magnetic field. chain, 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 ;

The slip frequency vector control orients the magnetic field according to the slip frequency vector, and uses the following formula to obtain the real-time torque _Tei :

Where, n _p is the number of motor pole pairs of the AC asynchronous motor, T _r is the rotor electromagnetic time constant, L _rd is the equivalent self-inductance of the rotor one-phase winding of the AC asynchronous motor, Ψ _r is the AC asynchronous motor The rotor flux of the motor, ω _s1 is the slip angular frequency;

The stator magnetic field orientation vector control performs the magnetic field orientation according to the direction of the stator flux vector, and uses the following formula to obtain the real-time torque _Tei :

T _ei =n _p Ψ _s i _sT ;

Where, n _p is the number of motor pole pairs of the AC asynchronous motor, Ψ _s is the stator flux linkage of the AC asynchronous motor, and i _sT is the torque component of the stator current;

The air gap magnetic field orientation vector control performs the magnetic field orientation according to the direction of the torque air gap flux vector, and uses the following formula to obtain the real-time torque _Tei :

T _ei =n _p Ψ _m i _sT ;

Among them, n _p is the number of motor pole pairs of the AC asynchronous motor, Ψ _m is the air gap flux linkage, and i _sT is the torque component of the stator current.

The above valve driver, wherein the core controller also includes:

The speed control unit is used to obtain the current speed of the valve using the vector control method or the feedback signal of the position sensor, correct the output speed of the AC asynchronous motor through the PID control algorithm, and superimpose it with the torque correction unit to correct the output torque. , to meet the speed requirements of each stage of opening or closing of the valve/door.

The above valve driver, wherein the core controller also includes:

A position control unit, configured to determine whether the position node of each stage of the valve/door opening or closing process has been reached according to the feedback signal of the position sensor, and further adjust the output torque according to the judgment result to meet the requirements of the valve/door. Turn on or off the control logic of each stage and the requirements for stop position accuracy.

In the above-mentioned valve driver, the position sensor is a full-stroke sensor and/or a point sensor to achieve full-stroke high-precision position control or accurate start/end position control.

In the above valve driver, the position sensor is installed on the output shaft of the AC asynchronous motor, the output shaft of the reduction transmission box or the driving mechanism, and is connected to the core controller.

The above valve driver, wherein the core controller also includes:

A torque calibration unit is connected to a torque calibration device, and performs torque calibration on the AC asynchronous motor through the torque calibration device to correct the output torque of the AC asynchronous motor.

In order to better achieve the above object, the present invention also provides an electric valve/gate, including a valve/gate, a transmission device, an AC asynchronous motor and a valve driver. The AC asynchronous motor communicates with the valve/gate through the transmission device. The valve driver is connected to the AC asynchronous motor, and controls the opening and closing of the valve/door through the AC asynchronous motor, wherein the valve driver is the above-mentioned valve driver, and the valve driver is connected to the AC asynchronous motor. The AC asynchronous motor is an integrated connection piece; or the valve driver and the AC asynchronous motor are arranged separately and connected through cables or wirelessly.

The technical effects of the present invention are:

This invention can realize precise control of the torque, speed and position of ordinary AC asynchronous motors according to the load changes of the switching valve/door throughout the stroke by optimizing the matching parameters of speed and torque, thereby ensuring that the valve/door is "closed tightly" and " "Stop accurately" and "Open"; at the same time, based on the starting phase, acceleration phase, uniform speed phase, deceleration phase, slow approach phase, torque control phase and stop phase of the valve/door displacement, phased combination control can be achieved to meet It meets the requirements of quick opening and closing of valves/doors, elimination of water hammer, regulating valve operating conditions, and fault response; through short-term "overfrequency" (overspeed) and "overcurrent" (overtorque), valve drivers can be selected compared to existing technologies. Smaller AC asynchronous motors can reduce product volume and weight, reduce costs, and improve the dynamic characteristics of the pipeline system; while improving the load smoothness control of ordinary AC asynchronous motors, it can also reduce the impact on the power grid.

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 invention.

Description of the drawings

Figure 1 is a schematic structural diagram of an electric valve/door according to an embodiment of the present invention;

Figure 2 is a schematic structural diagram of an electric valve/door according to another embodiment of the present invention;

Figure 3 is a structural block diagram of an electric valve/door according to an embodiment of the present invention;

Figure 4 is a structural block diagram of a valve driver according to an embodiment of the present invention;

Figure 5 is a structural block diagram of a valve driver according to another embodiment of the present invention;

Figure 6 is an equivalent circuit diagram of stator resistance identification according to an embodiment of the present invention;

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

Figure 8 is a motor inverse Γ equivalent circuit according to an embodiment of the present invention;

FIG. 9 is a diagram illustrating the corresponding relationship between the set torque and the output torque in torque calibration according to an embodiment of the present invention.

Among them, reference signs
1 valve/door
2 transmission device
21 reduction transmission box
22 drive mechanism
3AC asynchronous motor
4 valve driver
41 logic control module
42 frequency conversion control module
43 variable frequency drive module
44 core controller
45 signal conversion module/IO module
46 detection and protection modules
47 temperature control module
48 human-computer interaction module
5Torque calibration device
6 position sensors
7Torque sensor
8 power supply

Detailed ways

The structural principle and working principle of the present invention will be described in detail below in conjunction with the accompanying drawings:

Referring to Figures 1-3, Figure 1 is a schematic structural diagram of an electric valve/door according to one embodiment of the present invention. Figure 2 is a schematic structural diagram of an electric valve/door according to another embodiment of the present invention. Figure 3 is a schematic diagram of an electric valve/door according to one embodiment of the present invention. Valve/gate structure block diagram. The electric valve or electric door of the present invention includes a valve/door 1, a transmission device 2, an AC asynchronous motor 3 and a valve driver 4. The AC asynchronous motor 3 is connected to the valve/door 1 through the transmission device 2, so The valve driver 4 is connected to the power supply 8 and the AC asynchronous motor 3 respectively, and controls the opening and closing of the valve/door 1 through the AC asynchronous motor 3. The transmission device 2 may include a reduction transmission box 21 and a driving mechanism 22. The reduction transmission The box 21 is respectively connected to the output shaft of the AC asynchronous motor 3 and the input end of the driving mechanism 22. The output end of the driving mechanism 22 is connected to the valve/gate 1 to realize the driving of the valve/gate 1. The valve driver 4 and the AC asynchronous motor 3 can be an integral connection piece (see Figure 1); or the valve driver 4 and the AC asynchronous motor 3 can be installed separately and connected through cables or wirelessly (see Figure 2 ), the mechanical drive and the electrical drive can be separated 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/door of the present invention are relatively mature existing technologies, so they will not be described in detail here. Only the valve driver 4 and the valve driver of the present invention are described below. Its working principle is explained in detail.

Referring to Figures 4 and 5, Figure 4 is a structural block diagram of the valve driver 4 according to one embodiment of the present invention, and Figure 5 is a structural block diagram of the valve driver 4 according to another embodiment of the present invention. The valve driver 4 of the present invention includes a housing, a core controller 44 and a variable frequency drive module 43 installed in the housing. The variable frequency drive module 43 is connected to the core controller 44 and the AC asynchronous motor 3 respectively, so The core controller 44 adjusts the output torque or output torque limit of the variable frequency drive module 43 in real time to meet the response speed and control accuracy requirements of the valve/gate 1 . The core controller 44 serves as the signal judgment and logic control core, preferably a microcontroller and a DSP, and can be equipped with a logic processor, IO system, internal bus, etc.; the variable frequency 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. As shown in Figures 4 and 5, 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, and a power supply battery. and cable plug-ins, etc. The wireless communication module is used for connection and information exchange with remote controls and external portable devices. It can include infrared transceiver circuits, Bluetooth communication circuits, etc., as well as infrared communication, Bluetooth communication, serial bus communication, and Ethernet communication. Wait for the interface, you can Meets the wired or wireless connection between the valve driver 4 and the torque calibration device 5, host computer, 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 may include a rectification circuit , DC circuit, inverter circuit, detection circuit, etc.; IO module is used for connection, conversion and protection of input and output signals, and can include IO power supply circuit, digital input circuit, digital output circuit, analog input circuit, analog output Circuits, etc.; the human-computer interaction module 48 is used for inputting parameters and instructions and displaying operating status and alarm information, and can include a display screen and button panel, etc.; the fieldbus module is used for information exchange with the host computer and external monitoring equipment, and can include Modbus bus, CAN bus, etc.; the measurement conversion module is used to convert the sinusoidal voltage signal, TTL rectangular wave signal, HTL rectangular wave signal collected by the encoder from the valve/door displacement information into an open collector signal and feed it back to the logic control module 41, which can It includes a signal conversion circuit, a high-speed counting circuit, etc.; the temperature control module 47 is used to control the temperature of the entire machine, and may 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 switch valve/door 1.

The core controller 44 of this embodiment includes: a logic control unit for setting the corresponding set torque according to the requirements of each stage of the opening and closing process of the valve/door 1; sending the set torque to the The variable frequency drive module 43 uses the set torque as the output torque or the output torque limit to drive the AC asynchronous motor 3 to perform the corresponding opening or closing action of the valve/door 1; the real-time torque detection unit uses To obtain the real-time torque of the operation of the AC asynchronous motor 3 or the valve/gate 1; and a torque correction unit, based on the real-time torque and the set torque, using the set torque as input and the real-time torque as feedback, The PID control algorithm is used to correct the output torque, and the corrected output torque is sent to the variable frequency drive module 43 to adjust the response speed and control accuracy of the output torque according to the real-time torque.

In the embodiment shown in Figure 4, 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 above-mentioned logic Each unit such as the control unit, real-time torque detection unit, and torque correction unit can be integrated in the logic control module 41 or the frequency conversion control module 42; the logic control module 41 can be used for logic control of the entire machine, and can store and execute control programs. The logic The control module 41 can use a microcontroller, DSP, PLC, etc., and can include a program memory, a data memory, a central processing unit (CPU), an IO interface, an internal bus, etc. The frequency conversion control module 42 can be built by a single-chip microcomputer or a DSP chip and peripheral circuits. It is used to generate the motor's characteristic parameters and torque vector control algorithm, and drives the AC asynchronous motor 3 with the cooperation of the inverter circuit. It can include a program memory, a data memory, and a central processing unit. processor (CPU), IO interface and internal bus, etc.

In the embodiment of FIG. 5 , the logic control module 41 and the variable frequency control module 42 can be integrated into the core controller 44 , and the core controller 44 and the variable frequency drive module 43 can also be integrated into one, that is, the valve driver 4 The logic control, frequency conversion control and drive output functions can be separately arranged on different modules, or can be combined and integrated into one module. The present invention does not limit the structure, composition and integration method of the specific functional modules inside the valve driver 4. As long as the function of real-time adjustment of the output torque or output torque limit of the variable frequency drive module 43 can be realized to meet the response speed and control accuracy requirements of the valve/gate 1.

In the embodiment shown in FIG. 5 , the real-time torque can be directly obtained through a torque sensor 7 , which can be installed on the output shaft of the AC asynchronous motor 3 , the output shaft of the reduction transmission box 21 or the driving mechanism 22 The input shaft or the output shaft is connected to the real-time torque detection unit, and the real-time torque signal measured by it is transmitted to the real-time torque detection unit for torque correction.

In the embodiment shown in Figure 4, the real-time torque is preferably obtained through an output current detection circuit combined with a vector transformation method. The output current detection circuit detects the physical parameters of the AC asynchronous motor 3 and transmits them to the real-time torque detection unit. , the real-time torque detection unit obtains the real-time torque through calculation and transmits it to the torque correction unit. The physical parameters may include stator resistance, rotor resistance, stator and rotor mutual inductance, stator and rotor leakage inductance and no-load current. The three-phase AC signal of the AC asynchronous motor 3 can be converted into the torque component i _sT of the stator current and the excitation component i _sM of the stator current through coordinate transformation, and the rotor magnetic field oriented vector control and direct control are respectively adopted according to the different magnetic field orientations. The real-time torque is calculated by torque control, slip frequency vector control, stator magnetic field oriented vector control or air gap magnetic field oriented vector control. That is to say, vector torque control is used as the output method, the detection result of the torque detection circuit (in this embodiment, preferably the output current detection circuit) is used as the feedback signal, and the output torque is adjusted and controlled through PID closed loop, so that the drive valve/door 1 actually operates. The output torque operates within the range of the set torque, which is the expected value.

In order to realize vector control more accurately, the present invention can also use the valve driver 4 to identify the physical parameters of the AC asynchronous motor 3 in advance. First, the stator resistance, rotor resistance, stator and rotor mutual inductance, and stator and rotor leakage inductance of the AC asynchronous motor 3 are Collect other parameters to ensure the accuracy of the basic parameters in torque vector control. That is, the core controller 44 may also include a physical parameter identification unit for obtaining the physical parameters of the AC asynchronous motor 3 to perform more accurate torque vector control on the AC asynchronous motor 3 . It can input AC and DC excitation signals to the AC asynchronous motor 3 and monitor the stator current feedback in real time, and calculate and obtain the above-mentioned correlations based on the values and phase relationships of voltage and current. parameter. The no-load current is used to estimate the torque consumption (such as friction, ventilation, core loss, etc.) of the AC asynchronous motor 3 during operation and to compensate its output torque. The no-load current is preferably 20% to 50% of the rated current of the motor. .

This embodiment uses the output current detection circuit in the core controller 44 for parameter detection, and collects real-time torque (which can be calculated from the equivalent self-inductance of the rotor, the equivalent mutual inductance of the rotor, the rotor flux linkage, the stator current torque component, etc.) as the feedback quantity. , and uses the PID control principle to perform closed-loop control and correction of the output torque, and finally realizes torque vector control to ensure the torque response speed and control accuracy during the operation of the valve/gate 1. The stator resistance of this embodiment can be obtained in the following way:

Control the inverter power supply to output a single-phase DC voltage. At this time, the motor circuit diagram in this case can be simplified as shown in Figure 6:

Where, V` _dc = DC voltage, = stator current, R ₁ = stator resistance.

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

The rotor resistance, stator and rotor mutual inductance, and stator and rotor leakage inductance in this embodiment can be obtained in the following ways:

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

The vector equation of the stator and rotor of AC asynchronous motor 3 is:

in, p is the differential operator, R ₁ is the stator resistance, R _r is the rotor resistance, L _sσ is the stator leakage inductance, L _rσ is the rotor leakage inductance, L _m is the stator and rotor mutual inductance, ω is the rotor speed, cage rotor

The output W phase is disconnected, and the U phase and V phase control the on and off of the inverter according to the H-bridge sinusoidal voltage quenching and tempering signal, thereby generating a sinusoidal voltage excitation signal. Suppose the sinusoidal voltages of the U phase and V phase are Then the phase voltage and phase current in the AC asynchronous motor 3 satisfy the following relationship:

Among them, V _Un , V _Vn , and V _wn are the relative midpoint voltages of U-phase, V-phase, and W respectively.

At this time, the motor torque is 0, and the T-shaped equivalent circuit diagram of the motor at this time is shown in 7. Generally, the stator leakage inductance is the same as the rotor leakage inductance, that is, L _sσ = L _rσ . Figure 8 is an inverse Γ equivalent circuit diagram of a motor according to an embodiment of the present invention. It is a circuit after equivalent changes are made to T. After the changes, the relationship between the circuit parameters and T-type equivalent circuit parameters is:

It can be obtained from the figure:

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

From formula (1-6) to formula (1-9), we can get:

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

Apply sinusoidal voltage signals with frequencies f ₁ and f ₂ to the AC asynchronous motor 3 respectively to conduct a single-phase motor test to detect the equivalent impedance of the stator current molecules, and assume R`(f)=RR ₁ , from formula (1- 12) The calculation formula of the motor parameters under the inverse Γ equivalent circuit can be obtained

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

L _sσ ＝L _rσ ＝L` _sσ +L` _m -L _m (1-18)

In one embodiment of the present invention, the rotor magnetic field orientation vector control is preferably adopted, the magnetic field orientation is performed according to the direction of the rotor's full flux linkage vector, and the real-time torque _Te is obtained using the following formula:

Where, n _p is the number of motor pole pairs 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, and L _rd is the The equivalent self-inductance of the rotor one-phase winding, i _sT is the torque component of the stator current of the AC asynchronous motor 3 , and Ψ _r is the rotor flux linkage of the AC asynchronous motor 3 .

Its control principle is as follows:

Among them, Ψ _rM is the M-axis component of the rotor's full flux linkage; Ψ _rT is the T-axis component of the rotor's full flux linkage; 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 number of pole pairs of the motor; 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 linkage; is the rotor electromagnetic time constant; p is the differential operator; i _sM is the excitation component of the stator current.

In another embodiment of the present invention, direct torque control can also be used, and the real-time torque _Te is obtained using the following formula:

Among them, n _p is the number of motor pole pairs of the AC asynchronous motor 3, L _m is the stator and rotor mutual inductance, 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 .

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:

Stator flux linkage equation:

Among them, u _s is the stator shaft system voltage vector.

Neglecting the stator resistance voltage drop R _s i _s , we have:
Ψ≈∫u _s dt (2-18)

The torque equation is:

θ _sr is the torque angle, which is the angle between the vectors Ψ _s and Ψ _r .

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 obtain the real-time torque _Tei using the following formula:

Among them, n _p is the number of motor pole pairs of the AC asynchronous motor 3, T _r is the rotor electromagnetic time constant, L _rd is the equivalent self-inductance of the rotor one-phase winding of the AC asynchronous motor 3, Ψ _r is the rotor magnetic chain, ω _s1 is the slip angular frequency.

Slip frequency vector control can be carried out based on the rotor magnetic field directional vector control. Its control principle is as follows:

Among them, ω _s1 is the slip angular frequency.

In the fourth embodiment of the present invention, stator magnetic field orientation vector control is adopted, the magnetic field orientation is performed according to the direction of the stator flux vector, and the real-time torque _Te is obtained using the following formula:
T _ei =n _p Ψ _s i _sT ;

Where, n _p is the number of motor pole pairs of the AC asynchronous motor 3 , Ψ _s is the stator flux linkage of the AC asynchronous motor 3 , and _isT is the torque component of the stator current of the AC asynchronous motor 3 .

In this embodiment, the magnetic field is oriented according to the direction of the stator flux vector. The control principle is as follows:

T _ei ＝n _p Ψ _s i _sT (2-7)

Among them, Ψ _s is the stator flux; Ψ _sM is the M-axis component of the stator's full flux; Ψ _sT is the T-axis component of the stator's full flux; is the magnetic flux leakage coefficient; from formula (2-8), it can be seen that the stator flux linkage Ψ _s is i _sT and i _sM The functions of are coupled to each other, and a decoupling controller needs to be added. The control principle is as follows:

in, is the stator current excitation component given; is the stator flux linkage given; i _MT is the decoupling control signal; substituting equation (2-9) into the first equation of equation (2-8), we can get:

In order to realize the decoupled control of Ψ _s with the help of i _MT , make:
(1+σT _r p)L _sd i _MT -σL _sd T _r ω _s1 i _sT =0 (2-12)

After transformation, we can get:

Equation (2-13) is the decoupler module algorithm, which can directly calculate the stator flux vector Ψ _s through the voltage and current detected on the stator side, thereby achieving decoupling.

In the fifth embodiment of the present invention, air gap magnetic field orientation vector control is adopted, the magnetic field orientation is performed according to the direction of the torque air gap flux vector, and the real-time torque _Te is obtained using the following formula:
T _ei =n _p Ψ _m i _sT ;

Among them, n _p is the number of motor pole pairs of the AC asynchronous motor 3, Ψ _m is the air gap flux linkage, and _isT is the torque component of the stator current.

In this embodiment, the magnetic field is oriented according to the direction of the air gap flux linkage vector. The control principle is as follows:

T _ei ＝n _p Ψ _m i _sT (2-15)

The physical parameters that determine the torque control accuracy in the above vector control method will change with long-term operation, and the formula of the motor output torque in the above control method theoretically ignores the system mechanics. Friction resistance and other factors, therefore in an embodiment of the present invention, the core controller 44 may also include:

The torque calibration unit is connected to the torque calibration device 5 and performs torque calibration on the AC asynchronous motor 3 through the torque calibration device 5 for correcting the output torque of the AC asynchronous motor 3 . That is to say, the present invention can regularly adopt torque calibration to eliminate the adverse effects of the above factors and achieve long-term stability of the system torque control accuracy. The AC asynchronous motor 3 can be connected to the valve driver 4. After correctly setting the basic parameters of the system and performing parameter identification, select no less than 10 torque values evenly distributed within the range of 10% to 200% of the rated torque of the AC asynchronous motor. As a detection point, the valve driver 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, and the load covers 0 to the maximum output torque of the AC asynchronous motor 3; then the torque is calibrated The device 5 is installed and fixed on the output shaft of the AC asynchronous motor 3, and is connected to the valve driver 4 through a wired signal cable or a wireless communication module. The torque calibration device 5 is used to detect the corresponding points of each point of the AC asynchronous motor 3 using the torque calibration method. The output torque of the set torque is recorded and recorded; the above loading process of each detection point is repeated no less than 3 times and the arithmetic average is taken as the output torque detection result of this detection point; and the above test data is counted and analyzed by the valve driver 4, Compare the set torque and the corresponding output torque deviation and generate a set of statistical data. Based on the statistical data, generate a chart display or output of the corresponding relationship between the set torque and the corresponding output torque at each level (the display results can be charts and curves, and necessary prompt information for confirmation), used to correct the output torque of the AC asynchronous motor 3. After the relevant corresponding chart is confirmed, the valve driver 4 can perform corrections to obtain a more accurate output torque in the torque control stage. This embodiment only takes the comparison between the set torque and the corresponding output torque as an example. For details, please refer to the following table. The following table takes 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. The relationship between its output torque (i.e. the locked-rotor torque at the corresponding detection point) and the set torque. Among them, controlling and correcting the low speed and locked-rotor torque of the AC asynchronous motor 3 can achieve accurate sealing pressure during the closing process of the valve/door 1. The locked-rotor torque error of the AC asynchronous motor 3 is preferably controlled at ±10% of the rated torque ( Preferably within the range of ±4%) to stably and effectively control the sealing specific pressure of the valve/door 1 to close. At the same time, the discrete detection point data in the statistical table can also be integrated into a piecewise function describing the relationship between the set torque and the corresponding output torque (as shown in Figure 9, which is a relatively continuous, first-order polyline segment with different slopes) , for query and use in the torque control process.

Table 1 Comparison table of set torque and corresponding output torque

The above data describes the relationship between the set torque and the output torque of the AC asynchronous motor 3 with evenly distributed and sufficiently dense feature points. In this embodiment, when the set torque is within the rated torque range (which is also the torque range to be used in the torque control stage), the error between the set torque and the output torque is within the range of ±10% (preferably ±4%), and there is 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 expressed in the form of a piecewise straight line equation and used to correct the output torque. Since the test results in the correspondence table are discrete data, in actual use, the data between the test points is inserted and supplemented by the line segment equation between two adjacent points. For example, when the set torque is between 0.5 and 1.0Nm, according to the starting point (0.5, 0.47) and end point (1.0, 0.88) of the leftmost line segment in Figure 9, the relationship curve equation can be obtained as:
y=0.82x+0.06;

Among them, x is the set torque, and 0.5≤x≤1.0, and y is the output torque.

From this, piecewise equations can be used to correspond the set torque and the output torque, so as to achieve the purpose of correcting the output value and accurately controlling the torque.

In order to further improve the control accuracy, in an embodiment of the present invention, the core controller 44 may also include: a speed control unit, used to obtain the current speed of the valve by using the method of current detection combined with vector transformation or the feedback signal of the position sensor 6. The PID control algorithm corrects the output speed of the AC asynchronous motor 3 and superimposes it with the calculation result of the torque correction unit to further correct the output torque to meet the speed requirements of each stage of opening or closing of the valve/gate 1 .

In another embodiment of the present invention, the core controller 44 may further include: a position control unit, configured to determine whether each step of the opening or closing process of the valve/door 1 has been reached based on the feedback signal of the position sensor 6 . The position node of the stage is determined, and the output torque is further adjusted based on the judgment result combined with the feedback results of the speed control unit and torque correction unit to meet the control logic and stop position accuracy requirements of each stage of opening or closing of the valve/gate 1. In this embodiment, the position, speed, and torque of the valve/gate 1 can be monitored in real time. According to the nesting relationship, a nested control mode of torque loop, speed loop, and position loop can be used from the inside out. Among them, the torque loop directly affects Torque, fast response and high precision, can meet the requirements of real-time control of motor output torque; the speed loop works on the basis of the torque loop, and obtains the current value of valve/gate 1 from the feedback of valve driver 4 or position sensor 6 through the basic principle of vector control speed, and exerts influence through the torque loop to meet the speed requirements at different stages; the position loop works on the basis of the speed loop and torque loop as an optional and supplementary item, and is the outermost adjustment, which is based on the valve driver 4 or the position sensor 6 feedback to judge and adjust the output to meet the requirements of control logic and stop position accuracy.

The position sensor 6 may be a full-stroke sensor and/or a point sensor to achieve full-stroke high-precision position control or accurate start/end position control. The position sensor 6 can be installed on the output shaft of the AC asynchronous motor 3, the output shaft of the reduction transmission box 21 or the input shaft or output shaft of the driving mechanism 22, and communicates with the core controller through the signal conversion module/IO module 45 connect. The invention is compatible with full-stroke sensors and point-type sensors, and is suitable for combinations of full-stroke sensors, point-type sensors, full-stroke sensors and point position sensors 6 . In practice, the selection of the position sensor 6 is related to the type of the valve/gate 1, the mechanical structural characteristics of the valve/gate 1, the use environment of the valve/gate 1, and the production technology level of the valve/gate 1. Generally, it does not depend on the valve driver 4 Change according to needs. In a system pre-installed with a full-stroke sensor, the different stages of valve/door 1 execution are accurately divided according to continuous position signals (the present invention can include a starting stage, an acceleration stage, a uniform speed stage, a deceleration stage, a slow approach stage, and a torque control stage). and stop phase, etc.), reasonably control the starting position, end position, speed, torque, acceleration, deceleration and other parameters of each process to achieve the expected execution effect. The invention cooperates with different interface conversion hardware and can be adapted to various types of full-stroke sensors.

Among them, node-type sensors still occupy a certain proportion in valve actuator systems due to their low cost, easy installation, and strong environmental adaptability. In a system pre-installed with node position sensors, the different processes performed by the valve are limitedly identified and divided based on discrete node position signals, and the execution results of opening or closing are guaranteed while ensuring safety. In a system pre-installed with a full-stroke sensor and a point position sensor 6, the same as a system with only a pre-installed full-stroke sensor, the node point-type sensor acts as a protection device or safety redundant device for safety protection of extreme or special positions. The compatibility of the present invention in terms of sensor types and forms broadens its use scope and applicable environment, and also improves the safety of its applicable process.

The valve driver 4 of the present invention can be used to control the opening and closing of various valves/doors 1, such as sliding doors, swing doors, revolving doors, shutter doors, gate valves, globe valves, ball valves, butterfly valves, plug valves, air valves, etc. Control requirements of working conditions. Among them, the regulating valve achieves control of different flow characteristics by accurately adjusting the opening of the valve/gate 1 or the process movement speed, such as equal percentage control characteristics, direct control characteristics, quick opening control characteristics, and parabolic control characteristics. For the positioning of any position in the middle of the regulating valve, each adjustment can be regarded as a complete working movement process. For example, when the switching angle of a ball valve changes from 45° to 60° during flow adjustment, the working process it goes through is the starting stage, acceleration stage, uniform speed stage, deceleration stage, approach stage and stop stage. The switching valve needs to realize the switching action at a certain speed and needs to ensure the sealing when closing. Therefore, compared with the regulating valve, it can increase the torque control process. For example, the closing process of the gate valve can be divided into starting stage, acceleration stage, uniform speed stage, and deceleration. phase, slow approach phase, torque control phase and stop phase.

The present invention uses the valve driver 4 to perform torque vector control, torque calibration and motor parameter identification on the AC asynchronous motor 3, which can respectively realize dynamic control of the output torque and static correction of the set torque; in a multiple PID nesting manner, from the inside out. Establish the torque loop, speed loop and position loop respectively, and select the closed-loop level or nesting depth according to the needs of the different stages of the valve/gate 1 execution process, achieving full-stroke accuracy of the three closed loops of position, speed and torque of the ordinary AC asynchronous motor 3 Servo control is used to ensure that the execution process of the valve/gate 1 is rapid and precise, and the execution results are accurate and effective. That is, the external nested speed closed loop and position closed loop are used to nest the torque closed loop (such as current closed loop). While improving the response speed and control accuracy of the output torque, it also performs speed and position control during the execution phase where operating speed and positioning accuracy need to be ensured, further improving the efficiency, stability, accuracy and flexibility of the execution process. It can accurately control the specific pressure of the closing valve seal, and can achieve precise power control of the ordinary AC asynchronous motor 3 by optimizing the matching parameters of speed and torque according to the load change of the switching valve throughout the stroke, so as to achieve "tight closing" and "stop" of the valve/door. "accurately" and "can be opened"; at the same time, the startup phase based on the valve/gate displacement, The acceleration phase, uniform speed phase, deceleration phase, slow speed approach phase, torque control phase and stop phase can realize phased combination control, and match different control strategies according to the various working conditions of the valve/gate at the use site, such as opening /Close valve efficiency (time) priority, open/close valve position accuracy priority, open/close valve torque accuracy priority, open/close valve safety priority, open/close valve pipeline safety priority, open/close valve priority The stability of the pipeline system is given priority to meet the requirements of quick opening and closing, water hammer elimination, regulating valve working conditions, and fault response. Through short-term "overfrequency" (overspeed) and "overcurrent" (overtorque), smaller AC asynchronous motors 3 can be selected, thereby reducing product volume and weight and cost, and improving the dynamic characteristics of the pipeline system; achieving While controlling the load smoothness of ordinary AC asynchronous motor 3, it can also reduce the impact on the power grid.

Of course, the present invention can also have various other 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. However, these corresponding Changes and deformations should fall within the protection scope of the appended claims of the present invention.

Claims

A valve driver includes a housing, a core controller and a variable frequency drive module installed in the housing. The variable frequency drive module is respectively connected to the core controller and an AC asynchronous motor. It is characterized in that the core control The controller meets the valve/gate response speed and control accuracy requirements by adjusting the output torque or output torque limit of the variable frequency drive module in real time. The core controller includes:

The logic control unit sets the corresponding set torque according to the requirements of each stage of the valve/door opening and closing process, and sends the set torque to the variable frequency drive module. The variable frequency drive module uses the set The torque is the output torque or the output torque limit drives the AC asynchronous motor to perform the corresponding valve/gate opening or closing action;

A real-time torque detection unit to obtain the real-time torque of the AC asynchronous motor or valve/gate operation; and

A torque correction unit, based on the real-time torque and the set torque, using the set torque as input, using the real-time torque as feedback, and using a PID control algorithm to correct the output torque to adjust according to the real-time torque The response speed and control accuracy of the output torque.
The valve driver according to claim 1, characterized in that the real-time torque is directly obtained through a torque sensor, and the torque sensor is installed on the output shaft of the AC asynchronous motor, the output shaft of the reduction transmission box or the driving mechanism, And connected with the real-time torque detection unit, and transmits the measured real-time torque signal to the real-time torque detection unit.
The valve driver according to claim 1, wherein the real-time torque is obtained through an output current detection circuit combined with a vector transformation method, and the output current detection circuit detects the physical parameters of the AC asynchronous motor and transmits them to the real-time torque. A torque detection unit. The real-time torque detection unit calculates and obtains the real-time torque and transmits it to the torque correction unit. The physical parameters include stator resistance, rotor resistance, stator and rotor mutual inductance, stator and rotor leakage inductance and no-load current.
The valve driver according to claim 3, characterized in that the three-phase AC signal of the AC asynchronous motor is converted into the torque component i sT of the stator current and the excitation component i sM of the stator current through coordinate transformation, and is oriented according to the magnetic field The real-time torque is calculated using 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 respectively;

Wherein, the rotor magnetic field orientation vector control is carried out according to the direction of the rotor full flux linkage vector. field orientation, and use the following formula to obtain the real-time torque Te :

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

The direct torque control uses the following formula to obtain the real-time torque Tei :

Among them, n p is the number of motor pole pairs of the AC asynchronous motor, L m is the stator and rotor mutual inductance, L s is the self-inductance of the stator one-phase winding, L r is the self-inductance of the rotor one-phase winding, and Ψ s is the stator magnetic field. chain, 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 ;

The slip frequency vector control orients the magnetic field according to the slip frequency vector, and uses the following formula to obtain the real-time torque:

Where, n p is the number of motor pole pairs of the AC asynchronous motor, T r is the rotor electromagnetic time constant, L rd is the equivalent self-inductance of the rotor one-phase winding of the AC asynchronous motor, Ψ r is the AC asynchronous motor The rotor flux of the motor, ω s1 is the slip angular frequency;

The stator magnetic field orientation vector control performs the magnetic field orientation according to the direction of the stator flux vector, and uses the following formula to obtain the real-time torque Tei :
T ei =n p Ψ s i sT ;

Where, n p is the number of motor pole pairs of the AC asynchronous motor, Ψ s is the stator flux linkage of the AC asynchronous motor, and i sT is the torque component of the stator current;

The air gap magnetic field orientation vector control performs the magnetic field orientation according to the direction of the torque air gap flux vector, and uses the following formula to obtain the real-time torque Tei :
T ei =n p Ψ m i sT ;

Among them, n p is the number of motor pole pairs of the AC asynchronous motor, Ψ m is the air gap flux linkage, and i sT is the torque component of the stator current.
The valve driver according to any one of claims 1-4, wherein the core controller further includes:

The speed control unit is used to obtain the current speed of the valve using the vector control method or the feedback signal of the position sensor, correct the output speed of the AC asynchronous motor through the PID control algorithm, and superimpose it with the torque correction unit to correct the output torque. , to meet the speed requirements of each stage of opening or closing of the valve/door.
The valve driver according to claim 5, wherein the core controller further includes:

A position control unit, configured to determine whether the position node of each stage of the valve/door opening or closing process has been reached according to the feedback signal of the position sensor, and further adjust the output torque according to the judgment result to meet the requirements of the valve/door. Turn on or off the control logic of each stage and the requirements for stop position accuracy.
The valve driver according to claim 6, wherein the position sensor is a full-stroke sensor and/or a point sensor to achieve full-stroke high-precision position control or accurate start/end position control.
The valve driver according to claim 7, wherein the position sensor is installed on the output shaft of the AC asynchronous motor, the output shaft of the reduction transmission box or the driving mechanism, and is connected to the core controller.
The valve driver according to claim 1, 2, 3, 4, 6, 7 or 8, characterized in that the core controller further includes:

A torque calibration unit is connected to a torque calibration device, and performs torque calibration on the AC asynchronous motor through the torque calibration device to correct the output torque of the AC asynchronous motor.
An electric valve/door, including a valve/door, a transmission device, an AC asynchronous motor and a valve driver. The AC asynchronous motor is connected to the valve/door through the transmission device, and the valve driver is connected to the AC asynchronous motor. is connected, and controls the opening and closing of the valve/door through the AC asynchronous motor, characterized in that the valve driver is the valve driver according to any one of the above claims 1-9, and the valve driver is connected to the valve driver. The AC asynchronous motor is an integrated connection piece; or the valve driver and the AC asynchronous motor are arranged separately and connected through cables or wirelessly.