Valve positioner driving circuit and control method thereof

Abstract

The invention provides a valve positioner driving circuit and a control method thereof.The valve positioner driving circuit comprises a signal conversion module, a driving module and a power source control module, and a valve position control signal in driving signals is converted into driving current through the signal conversion module; the valve position positioner is driven by the driving module based on the driving current to adjust the valve position, and when the valve position changes, the power supply voltage of the driving module is switched into second voltage with higher voltage difference through the power supply control module. According to the valve positioner driving circuit provided by the invention, the continuity of the driving current is improved based on the signal conversion module, and when the valve position control signal is changed, the power supply voltage of the driving module is switched through the power supply control module, so that the current change time in the driving module is shortened, and the valve positioning accuracy is improved. And the control hysteresis caused by the inductive part of the coil is reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of valve positioner, in particular to a valve positioner driving circuit and a control method thereof. BACKGROUND

[0002] With the rapid development of electronic power, intelligent valve positioners are applied to multiple industries such as power and chemical industry; in some special working conditions, it is necessary to quickly open and close the valve positioner, and in the daily use process, the rapidity of the valve positioner is also one of the conditions for measuring the performance of the valve positioner.

[0003] In the prior art, the I / P conversion unit (electrical conversion unit) of the valve positioner is mainly divided into piezoelectric valve type and nozzle baffle type; the control of the piezoelectric valve type I / P conversion unit is mainly to output a pulse signal by a main controller in the valve positioner to control the conduction and turn-off of the switching tube, so that the ceramic sheet is bent to realize air intake and exhaust, and this control method has certain defects in the continuity of control, and the service life of the switching tube is also affected under the high-frequency switching state. Because the nozzle baffle type coil belongs to a resistive inductive load, due to the existence of inductance, when adjusting the coil current, a counter electromotive force is formed on the coil, which hinders the driving current from quickly reaching the set value, and the response speed of the valve positioner is slow.

[0004] Therefore, how to provide a valve positioner capable of quickly improving the valve adjustment speed is a technical problem to be solved at present. SUMMARY

[0005] The present application provides a valve positioner driving circuit and a control method thereof to solve the above problems of slow response speed and discontinuous control of the valve positioner.

[0006] In a first aspect, the present application provides a valve positioner driving circuit, comprising: a signal conversion module connected to a driving signal and converting a valve position control signal in the driving signal into a driving current; a driving module connected to the signal conversion module and used for driving a valve positioner according to the driving current; a power supply control module connected to the driving module and used for switching the power supply voltage of the driving module from a first voltage to a second voltage based on a power supply control signal when the valve position of the valve positioner changes, so as to improve the response speed of the valve positioner; wherein the second voltage is greater than the first voltage.

[0007] In an embodiment of the present application, the drive circuit further comprises a protection module connected to the drive module, for energy conversion of overcurrent energy when overcurrent is generated in the drive module.

[0008] In an embodiment of the present application, the signal conversion module comprises a signal switching unit and an operational amplifier unit, the signal switching unit is connected to a clock signal, the valve position control signal and a chip selection signal, and under the control of the clock signal and the chip selection signal, converts the valve position control signal into an analog voltage signal; the operational amplifier unit is connected to the signal switching unit, amplifies the analog voltage signal and converts it into the drive current.

[0009] In an embodiment of the present application, the signal switching unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a third capacitor and a first chip, the digital ground end of the first chip is connected to ground through the first resistor, the power supply end of the first chip is connected to the first end of the second capacitor through the first capacitor, the first end of the second capacitor is also connected to ground, the second end of the second capacitor is connected to a first voltage through the second resistor, the first voltage is connected to the chip selection end of the first chip through the third resistor, the reference end of the first chip is connected to a second voltage, the analog ground end of the first chip is connected to ground, and the output end of the first chip is connected to the first end of the third capacitor through the fourth resistor, the second end of the third capacitor is connected to ground, wherein the clock end of the first chip is connected to the clock signal, the input end of the first chip is connected to the valve position control signal, and the first end of the third capacitor outputs the analog voltage signal.

[0010] In an embodiment of the present application, the operational amplifier unit comprises a fifth resistor, a sixth resistor, a seventh resistor, a fourth capacitor, a first NPN transistor and an operational amplifier, the output end of the operational amplifier is connected to the base of the first NPN transistor through the fifth resistor, the first end of the fourth capacitor is connected to the output end of the operational amplifier, the second end of the fourth capacitor is connected to the inverting input end of the operational amplifier, the inverting input end of the operational amplifier is connected to the emitter of the first NPN transistor through the sixth resistor, and the emitter of the first NPN transistor is connected to ground through the seventh resistor, wherein the non-inverting input end of the operational amplifier is connected to the analog voltage signal, and the collector of the first NPN transistor outputs the drive current.

[0011] In an embodiment of the present application, the power control module comprises an eighth resistor, a ninth resistor, a tenth resistor, a first PMOS transistor, a first NMOS transistor and a second NMOS transistor, a source of the first PMOS transistor is connected to a second voltage, a drain of the first PMOS transistor is connected to a source of the first NMOS transistor, a drain of the first NMOS transistor is connected to a first voltage, a gate of the first PMOS transistor is connected to a first end of the eighth resistor, a second end of the eighth resistor is connected to the second voltage, the first end of the eighth resistor is connected to a source of the second NMOS transistor through the ninth resistor, a gate of the first NMOS transistor is connected to the source of the second NMOS transistor, a drain of the second NMOS transistor is connected to ground, a gate of the second NMOS transistor is connected to a first end of the tenth resistor, wherein a second end of the tenth resistor is connected to the power control signal, and the drain of the first PMOS transistor outputs the power supply voltage.

[0012] In an embodiment of the present application, the protection module comprises an eleventh resistor, a twelfth resistor, a fifth capacitor, a first diode and a second diode, a first end of the eleventh resistor is connected to a cathode of the first diode, an anode of the first diode is connected to an anode of the second diode, a cathode of the second diode is connected to a first end of the fifth capacitor, the first end of the fifth capacitor is also connected to a first end of the twelfth resistor, a second end of the eleventh resistor is connected to a second end of the fifth capacitor, wherein the first end of the eleventh resistor is connected to the driving current, the first end of the fifth capacitor is connected to the power supply voltage, and the first end of the eleventh resistor and the second end of the twelfth resistor are connected to the driving module.

[0013] In a second aspect, the present application further provides a control method applied to the valve positioner driving circuit as described above, the method comprising: obtaining a driving signal and a power control signal; performing signal conversion on a valve position control signal in the driving signal to obtain a driving current, so as to drive the valve positioner based on the driving current; switching a power supply voltage of a driving module from a first voltage to a second voltage based on the power control signal when the valve positioner changes, wherein the second voltage is greater than the first voltage.

[0014] In an embodiment of the present application, performing signal conversion on the valve position control signal to obtain a driving current comprises: converting the valve position control signal into an analog voltage signal under the control of a clock signal and a chip select signal in the driving signal; and performing voltage-current conversion on the analog voltage signal to obtain the driving current.

[0015] The beneficial effects of the present application: the present application provides a valve positioner drive circuit and a control method thereof, the valve positioner drive circuit comprises a signal conversion module, a drive module and a power supply control module, the valve position control signal in the drive signal is converted into a drive current through the signal conversion module, the valve positioner is driven by the drive module based on the drive current to adjust the valve position, when the valve position changes, the power supply voltage of the drive module is switched to a second voltage with higher voltage difference through the power supply control module. The valve positioner drive circuit provided by the present application improves the continuity of the drive current based on the signal conversion module, when the valve position control signal changes, the power supply voltage of the drive module is switched through the power supply control module, thereby accelerating the current change time in the drive module and reducing the inductive part of the coil to cause the hysteresis of the control. BRIEF DESCRIPTION OF DRAWINGS

[0016] The drawings incorporated into the specification and forming a part thereof show embodiments consistent with the present application and, together with the specification, serve to explain the principles of the application. It is apparent that the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those skilled in the art.

[0017] In the drawings: Figure 1 A block diagram of the valve positioner drive circuit provided in the embodiment of the present application is shown; Figure 2 A block diagram of the valve positioner drive circuit provided in the embodiment of the present application is shown; Figure 3 A specific structure diagram of the signal conversion module provided in the embodiment of the present application is shown; Figure 4 A specific structure diagram of the power supply control module provided in the embodiment of the present application is shown; Figure 5 A specific structure diagram of the protection module and the drive module provided in the embodiment of the present application is shown.

[0018] Reference signs: 110 - signal conversion module; 111 - signal switching unit; 112 - operational amplifier unit; 120 - drive module; 130 - power supply control module; 140 - protection module; Iq - drive current; Vs - power supply voltage; K1 - power supply control signal; V1 - first voltage; V2 - second voltage; CLK - clock signal; CS1 - chip selection signal; D1 - valve position control signal; Vin - analog voltage signal. DETAILED DESCRIPTION

[0019] The advantages and effects of the present application can be easily understood by those skilled in the art from the description of the present application. The present application can also be implemented or applied by different specific embodiments, and the details in the description can be modified or changed based on different views and applications without departing from the spirit of the present application. The following examples and features in the examples can be combined with each other without conflict.

[0020] It should be noted that the diagrams provided in the following examples only illustrate the basic concept of the present application in a schematic manner, and the components shown in the drawings are only related to the present application, not drawn according to the number, shape and size of the components in actual implementation. The shape, number and proportion of each component in actual implementation can be arbitrarily changed, and the layout pattern of the components can be more complex.

[0021] In the following description, a large number of details are discussed to provide a more thorough explanation of the embodiments of the present application. However, it is obvious to those skilled in the art that the embodiments of the present application can be implemented without these specific details, and in other embodiments, well-known structures and devices are shown in block diagrams rather than in detail to avoid making the embodiments of the present application difficult to understand.

[0022] The I / P conversion unit (electrical conversion unit) is the core component of the industrial automation system for converting current signals into pneumatic signals, mainly used for the control of pneumatic regulating valves.

[0023] With the rapid development of electronic power, intelligent valve positioners are applied in many industries such as power and chemical industry; in some special working conditions, the valve positioner needs to be quickly opened and closed, and in the daily use process, the rapidity of the valve positioner is also one of the conditions for measuring its performance.

[0024] The I / P conversion unit in the valve positioner is the component that drives the actuator to act, and the nozzle baffle type I / P conversion unit has lower requirements for the cleanliness of the air source and good stability, so the nozzle baffle type valve positioner is widely used in valve control systems. It changes the distance between the nozzle and the nozzle baffle by controlling the electromagnetic force generated by the coil, changes the back pressure of the nozzle, and after the back pressure passes through the amplifier, it enters the valve cylinder to drive the valve rod to act and adjust the valve position.

[0025] In the prior art, the I / P conversion units of the valve positioner are mainly divided into piezoelectric valve type and nozzle baffle type; the control of the piezoelectric valve type I / P conversion unit is mainly through a main controller to output a pulse signal to control the conduction and turn-off of a switching tube, so that the ceramic sheet is bent to realize air intake and exhaust, and the control circuit and method have certain defects in the continuity of control, and the switching tube is switched at high frequency, and the service life is also affected. Since the nozzle baffle type coil belongs to a resistive inductive load, due to the existence of inductance, when the coil current is adjusted, a counter electromotive force is formed on the coil, which hinders the driving current from quickly reaching the set value, and the response speed of the valve positioner is slow.

[0026] To solve the above problems, as shown in Figure 1 The present application provides a valve positioner driving circuit, comprising: The signal conversion module 110 receives the driving signal and converts the valve position control signal D1 in the driving signal into a driving current Iq. The driving module 120 is connected with the signal conversion module 110 and is used for driving the valve positioner according to the driving current Iq. The power supply control module 130 receives a power supply control signal K1 and is connected with the driving module 120, and is used for switching the power supply voltage Vs of the driving module 120 from a first voltage V1 to a second voltage V2 based on the power supply control signal K1 when the valve position of the valve positioner changes, so as to improve the response speed of the valve positioner. Wherein, the second voltage V2 is greater than the first voltage V1.

[0027] It should be noted that the driving module 120 is an I / P conversion unit in the valve positioner, that is, the driving module 120 can be a nozzle baffle type.

[0028] In detail, as shown in Figure 2 The driving circuit further comprises a protection module 140 connected with the driving module 120, which is used for energy transfer when overcurrent occurs in the driving module 120, so as to prevent overcurrent and overvoltage from occurring in the driving module 120.

[0029] In detail, the signal conversion module 110 comprises a signal switching unit 111 and an operational amplifier unit 112, the signal switching unit 111 receives a clock signal CLK, a valve position control signal D1 and a chip selection signal CS1, and converts the valve position control signal D1 into an analog voltage signal Vin under the control of the clock signal CLK and the chip selection signal CS1; the operational amplifier unit 112 is connected with the signal switching unit 111, amplifies the analog voltage signal Vin, and converts it into a driving current Iq.

[0030] More specifically, as shown in Figure 3As shown, the signal switching unit 111 includes a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a first capacitor C1, a second capacitor C2, a third capacitor C3, and a first chip U1. The digital ground end of the first chip U1 is connected to the ground through the first resistor R1. The power supply end of the first chip U1 is connected to the first end of the second capacitor C2 through the first capacitor C1. The first end of the second capacitor C2 is also connected to the ground. The second end of the second capacitor C2 is connected to the first voltage V1 through the second resistor R2. The first voltage V1 is connected to the chip select end of the first chip U1 through the third resistor R3. The reference end of the first chip U1 is connected to the second voltage V2. The analog ground end of the first chip U1 is connected to the ground. The output end of the first chip U1 is connected to the first end of the third capacitor C3 through the fourth resistor R4. The second end of the third capacitor C3 is connected to the ground. The clock end of the first chip U1 is connected to the clock signal CLK. The input end of the first chip U1 is connected to the valve position control signal D1. The first end of the third capacitor C3 outputs the analog voltage signal Vin.

[0031] It should be emphasized that the first voltage V1 and the second voltage V2 can be converted from the 4-20mA current signal input by the valve positioner.

[0032] In more detail, as shown in Figure 3 The operational amplifier unit 112 includes a fifth resistor R5, a sixth resistor R6, a seventh resistor R7, a fourth capacitor C4, a first NPN transistor Q1, and an operational amplifier COMP. The output end of the operational amplifier COMP is connected to the base of the first NPN transistor Q1 through the fifth resistor R5. The first end of the fourth capacitor C4 is connected to the output end of the operational amplifier COMP. The second end of the fourth capacitor C4 is connected to the negative input end of the operational amplifier COMP. The negative input end of the operational amplifier COMP is connected to the emitter of the first NPN transistor Q1 through the sixth resistor R6. The emitter of the first NPN transistor Q1 is connected to the ground through the seventh resistor R7. The positive input end of the operational amplifier COMP is connected to the analog voltage signal Vin. The positive input end of the operational amplifier COMP is connected to the second end of the fourth resistor R4. The collector of the first NPN transistor Q1 outputs the driving current Iq.

[0033] In more detail, as shown in Figure 4As shown, the power control module 130 includes an eighth resistor R8, a ninth resistor R9, a tenth resistor R10, a first PMOS tube P1, a first NMOS tube M1 and a second NMOS tube M2, the source of the first PMOS tube P1 is connected to the second voltage V2, the drain of the first PMOS tube P1 is connected to the source of the first NMOS tube M1, the drain of the first NMOS tube M1 is connected to the first voltage V1, the gate of the first PMOS tube P1 is connected to the first end of the eighth resistor R8, the second end of the eighth resistor R8 is connected to the second voltage V2, the first end of the eighth resistor R8 is connected to the source of the second NMOS tube M2 through the ninth resistor R9, the gate of the first NMOS tube M1 is connected to the source of the second NMOS tube M2, the drain of the second NMOS tube M2 is connected to the ground, the gate of the second NMOS tube M2 is connected to the first end of the tenth resistor R10, wherein the second end of the tenth resistor R10 is connected to the power control signal K1, and the drain of the first PMOS tube P1 outputs the supply voltage Vs.

[0034] In more detail, as shown in Figure 5 The protection module 140 includes an eleventh resistor R11, a twelfth resistor R12, a fifth capacitor C5, a first diode D1 and a second diode D2, the first end of the eleventh resistor R11 is connected to the cathode of the first diode D1, the anode of the first diode D1 is connected to the anode of the second diode D2, the cathode of the second diode D2 is connected to the first end of the fifth capacitor C5, the first end of the fifth capacitor C5 is also connected to the first end of the twelfth resistor R12, the second end of the eleventh resistor R11 is connected to the second end of the fifth capacitor C5, wherein the first end of the eleventh resistor R11 is connected to the collector of the first NPN transistor Q1, the first end of the eleventh resistor R11 is connected to the driving current Iq, the first end of the fifth capacitor C5 is connected to the drain of the first PMOS tube P1, the first end of the fifth capacitor C5 is connected to the supply voltage Vs, the first end of the eleventh resistor R11 is connected to the first terminal post J1 of the nozzle baffle coil (the driving module 120), the first end of the fifth capacitor C5 is connected to the second terminal post J2 of the nozzle baffle coil (the driving module 120), and the first end of the eleventh resistor R11 and the second end of the twelfth resistor R12 are connected to the driving module 120.

[0035] As shown in Figures 1 to 5 The working principle of the valve positioner driving circuit provided by the application is as follows: As shown in Figure 1 The signal conversion module 110 converts the valve position control signal D1 in the driving signal into a driving current Iq, the driving module 120 is connected to the signal conversion module 120 and can drive the valve positioner according to the driving current Iq, when the valve position of the valve positioner changes, the power control module 130 controls the supply voltage Vs of the driving module 120 to switch from the first voltage V1 to the second voltage V2 according to the power control signal K1, thereby improving the hysteresis of the valve positioner control. Figure 2As shown, the protection module 140 is connected to the drive module 120. The protection module 140 is used to prevent the large current generated in the nozzle baffle coil (drive module 120) from burning out the coil, and to quickly consume the remaining energy in the coil when power is lost.

[0036] like Figure 3 As shown, the first chip U1 in the signal conversion module 110 needs to be compatible with serial peripheral interface communication in order to realize master-slave communication between the main controller in the valve positioner and the first chip U1. The main controller in the valve positioner needs to provide a drive signal to the first chip U1. The drive signal includes a clock signal CLK, a chip select signal CS1 and a valve position control signal D1. The clock signal CLK serves as the working clock of the first chip U1. The chip select signal CS1 controls whether the first chip U1 outputs an analog voltage signal Vin. The valve position control signal D1 calculates the output digital signal based on the target valve position and the current valve position. The first NPN transistor Q1 and the sixth resistor R6 form a negative feedback loop. At this time, the calculation expression of the drive current Iq is as shown in (1): (1) Where Iq is the driving current, Vin is the analog voltage signal, and R7 is the seventh resistor.

[0037] In addition, such as Figure 3 As shown, in the signal conversion module 110, the first resistor R1 is a zero-ohm resistor to reduce the interference of digital noise on the analog circuit. The second resistor R2 and the fifth resistor R5 are current-limiting resistors. The third resistor R3 is a pull-up resistor. The fourth resistor R4 and the third capacitor C3 form a filter structure between a capacitor and a resistor. The first capacitor C1, the second capacitor C2 and the fourth capacitor C4 are filter capacitors.

[0038] like Figure 4 As shown, in the power control module 130, the main controller in the valve positioner sends a power control signal K1 to change the supply voltage Vs of the nozzle baffle coil (drive module 120). When the power control signal K1 is low, the first PMOS transistor P1 and the second NMOS transistor M2 are turned off, and the first NMOS transistor M1 is turned on. At this time, the supply voltage Vs is the first voltage V1. When the power control signal K1 is high, the first PMOS transistor P1 and the second NMOS transistor M2 are turned on, and the first NMOS transistor M1 is turned off. At this time, the supply voltage Vs is the second voltage V2. The eighth resistor R8 and the ninth resistor R9 are voltage divider resistors, and the tenth resistor R10 is a current limiting resistor.

[0039] like Figure 5 As shown, in the protection module 140, the first diode D1 and the second diode D2 are connected in reverse series to prevent excessive voltage from being generated across the nozzle baffle coil. The eleventh resistor R11 and the fifth capacitor C5 form a path for absorbing energy, and the twelfth resistor R12 is a current-limiting resistor.

[0040] As shown in Figure 5 , the nozzle baffle coil (the driving module 120) can be regarded as a resistive load, and its equivalent inductance value is L and its equivalent resistance value is Rq. Let the voltage between the collector and the emitter of the first NPN transistor Q1 be Vec, and the voltage across the nozzle baffle coil (the driving module 120) be Vq. The current change loop is composed of the power supply voltage Vs, the nozzle baffle coil (the driving module 120), the first NPN transistor Q1 and the seventh resistor R7. If the current in the nozzle baffle coil (the driving module 120) changes, the transient voltage across the nozzle baffle coil (the driving module 120) at this time is shown in expression (2): (2) wherein Vq is the voltage between the two ends of the nozzle baffle coil, L is the equivalent inductance of the nozzle baffle coil (the driving module 120), is the current change rate of the current change loop, Iq is the driving current, and Rq is the equivalent resistance of the nozzle baffle coil (the driving module 120).

[0041] The power supply voltage Vs of the nozzle baffle coil (the driving module 120) is shown in expression (3): + Vec + Iq R7 (3) wherein Vs is the power supply voltage, L is the equivalent inductance of the nozzle baffle coil (the driving module 120), is the current change rate of the current change loop, Iq is the driving current, Rq is the equivalent resistance of the nozzle baffle coil (the driving module 120), Vec is the voltage between the collector and the emitter of the first NPN transistor Q1, and R7 is the seventh resistor.

[0042] Expression (3) is arranged to obtain expression (4): (4) wherein Vs is the power supply voltage, L is the equivalent inductance of the nozzle baffle coil (the driving module 120), is the current change rate of the current change loop, Iq is the driving current, Rq is the equivalent resistance of the nozzle baffle coil (the driving module 120), Vec is the voltage between the collector and the emitter of the first NPN transistor Q1, and R7 is the seventh resistor.

[0043] When the power supply voltage Vs is the first voltage V1, it is shown in expression (5): (5) wherein V1 is the first voltage, L is the equivalent inductance of the nozzle baffle coil (the driving module 120), is a current change rate of the current change loop, Iq is a drive current, Rq is an equivalent resistance of the nozzle flap coil (the drive module 120), Vec is a voltage between a collector and an emitter of the first NPN transistor Q1, and R7 is a seventh resistance.

[0044] When the supply voltage Vs is the second voltage V2, as shown in expression (6): (6) wherein V2 is the second voltage, L is an equivalent inductance of the nozzle flap coil (the drive module 120), is a current change rate of the current change loop, Iq is a drive current, Rq is an equivalent resistance of the nozzle flap coil (the drive module 120), Vec is a voltage between a collector and an emitter of the first NPN transistor Q1, and R7 is a seventh resistance.

[0045] When the valve position of the valve positioner changes, the main controller in the valve positioner sends the valve position control signal D1 to the signal conversion module 110, and sends the power supply control signal K1 to the power supply control module 130, and the supply voltage Vs of the nozzle flap coil (the drive module 120) is switched from the first voltage V1 to the second voltage V2, and because the second voltage V2 is greater than the first voltage V1, therefore, becomes larger, and the current in the nozzle flap coil (the drive module 120) reaches the preset current threshold value, so that the nozzle flap back pressure is quickly adjusted.

[0046] After the driving of the valve positioner is completed, the supply voltage Vs of the nozzle flap coil (the drive module 120) needs to be adjusted from the second voltage V2 to the first voltage V1.

[0047] The application further provides a control method applied to the valve positioner driving circuit as described above, and the method comprises the following steps: obtaining a drive signal and a power supply control signal K1; signal converting the valve position control signal D1 in the drive signal to obtain a drive current Iq, and driving the valve positioner based on the drive current Iq; When the valve positioner changes, the supply voltage Vs of the drive module 120 is switched from the first voltage V1 to the second voltage V2 based on the power supply control signal K1, and the second voltage V2 is greater than the first voltage V1.

[0048] Specifically, when the valve position of the valve positioner changes, the main controller in the valve positioner generates a valve position control signal D1 of a digital signal according to the current valve position and the target valve position, the main controller sends a driving signal to the signal conversion module 110, the driving signal includes the valve position control signal D1, the clock signal CLK and the chip selection signal CS1, the valve position control signal D1 is signal-converted by the signal conversion module 110 into a driving current Iq for driving the valve positioner, at the same time, the main controller also sends a high-level power supply control signal K1 to the power supply control module 130, the power supply voltage Vs of the driving module 120 is switched from the first voltage V1 to the second voltage V2, the power supply voltage Vs of the nozzle baffle coil (the driving module 120) is increased, the driving current Iq is accelerated to change from the last set value to the current set value, because of the low-power requirement of the circuit, the power supply voltage Vs of the nozzle baffle coil (the driving module 120) is switched to the first voltage V1 in a switching time set in the control period, and the second voltage V2 cannot be used as the power supply voltage Vs of the nozzle baffle coil (the driving module 120) for a long time.

[0049] In detail, the signal conversion of the valve position control signal D1 to obtain the driving current Iq includes: under the control of the clock signal CLK and the chip selection signal CS1 in the driving signal, the valve position control signal D1 is converted into an analog voltage signal Vin; the analog voltage signal Vin is voltage-current converted to obtain the driving current Iq. Specifically, under the triggering of the clock signal CLK, the signal switching unit 111 inputs a level that makes the first chip U1 output the analog voltage signal Vin, the signal switching unit 111 outputs the analog voltage signal Vin, the operational amplifier unit 112 amplifies and voltage-current converts the analog voltage signal Vin to obtain the driving current Iq.

[0050] The valve positioner driving circuit and the control method thereof provided by the application include a signal conversion module, a driving module, a power supply control module and a protection module, the valve position control signal in the driving signal is converted into a driving current by the signal conversion module, the valve position regulator is driven by the driving module based on the driving current to adjust the valve position; when the valve position changes, the power supply voltage of the driving module is switched to a second voltage with a higher voltage difference by the power supply control module, and the driving module is overcurrent and overvoltage protected by the protection module. The valve positioner driving circuit provided by the application improves the continuity of the driving current based on the signal conversion module, the power supply voltage of the driving module is switched by the power supply control module when the valve position control signal changes, so that the current change time in the driving module is accelerated, the hysteresis caused by the inductive part of the coil is reduced, and the driving module is overvoltage and overcurrent protected.

[0051] The above embodiments are only illustrative of the principles of the present application and its efficacy, and are not intended to limit the present application. Any modification or change made by any person skilled in the art without departing from the spirit and scope of the present application shall be covered by the claims of the present application.

Claims

1. A valve positioner drive circuit, characterized by, The application relates to a driving circuit for a valve positioner. The driving circuit comprises a signal conversion module, a driving module and a power supply control module. The signal conversion module receives a driving signal and converts a valve position control signal in the driving signal into a driving current. The driving module is connected to the signal conversion module and drives the valve positioner according to the driving current. The power supply control module receives a power supply control signal and is connected to the driving module.

2. The valve positioner drive circuit of claim 1, wherein, When the valve position of the valve positioner changes, the power supply control module switches the power supply voltage of the driving module from a first voltage to a second voltage based on the power supply control signal to improve the response speed of the valve positioner.

3. The valve positioner drive circuit of claim 1, wherein, The second voltage is greater than the first voltage.

4. The valve positioner drive circuit of claim 3, wherein, The driving circuit further comprises a protection module connected to the driving module.

5. The valve positioner drive circuit of claim 4, wherein, When overcurrent occurs in the driving module, the protection module performs energy transfer on the overcurrent energy. The signal conversion module comprises a signal switching unit and an operational amplifier unit. The signal switching unit receives a clock signal, the valve position control signal and a chip selection signal. Under the control of the clock signal and the chip selection signal, the signal switching unit converts the valve position control signal into an analog voltage signal. The operational amplifier unit is connected to the signal switching unit. The operational amplifier unit amplifies the analog voltage signal and converts the analog voltage signal into the driving current. The signal switching unit comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a first capacitor, a second capacitor, a third capacitor and a first chip. The digital ground end of the first chip is connected to the ground through the first resistor. The power supply end of the first chip is connected to the first end of the second capacitor through the first capacitor. The first end of the second capacitor is also connected to the ground. The second end of the second capacitor is connected to the first voltage through the second resistor. The first voltage is connected to the chip selection end of the first chip through the third resistor. The reference end of the first chip is connected to the second voltage. The analog ground end of the first chip is connected to the ground. The output end of the first chip is connected to the first end of the third capacitor through the fourth resistor. The second end of the third capacitor is connected to the ground. The clock end of the first chip is connected to the clock signal. The input end of the first chip is connected to the valve position control signal. The first end of the third capacitor outputs the analog voltage signal. The operational amplifier unit comprises a fifth resistor, a sixth resistor, a seventh resistor, a fourth capacitor, a first NPN transistor and an operational amplifier. The output end of the operational amplifier is connected to the base of the first NPN transistor through the fifth resistor. The first end of the fourth capacitor is connected to the output end of the operational amplifier. The second end of the fourth capacitor is connected to the inverting input end of the operational amplifier. The inverting input end of the operational amplifier is connected to the emitter of the first NPN transistor through the sixth resistor. The emitter of the first NPN transistor is connected to the ground through the seventh resistor. The non-inverting input end of the operational amplifier is connected to the analog voltage signal. The collector of the first NPN transistor outputs the driving current.

6. The valve positioner drive circuit of claim 1, wherein, The power supply control module includes an eighth resistor, a ninth resistor, a tenth resistor, a first PMOS tube, a first NMOS tube and a second NMOS tube, the source of the first PMOS tube is connected to a second voltage, the drain of the first PMOS tube is connected to the source of the first NMOS tube, the drain of the first NMOS tube is connected to a first voltage, the gate of the first PMOS tube is connected to the first end of the eighth resistor, the second end of the eighth resistor is connected to the second voltage, the first end of the eighth resistor is connected to the source of the second NMOS tube through the ninth resistor, the gate of the first NMOS tube is connected to the source of the second NMOS tube, the drain of the second NMOS tube is connected to ground, the gate of the second NMOS tube is connected to the first end of the tenth resistor, wherein the second end of the tenth resistor is connected to the power supply control signal, and the drain of the first PMOS tube outputs the power supply voltage.

7. The valve positioner drive circuit of claim 2, wherein, The protection module includes an eleventh resistor, a twelfth resistor, a fifth capacitor, a first diode and a second diode, the first end of the eleventh resistor is connected to the cathode of the first diode, the anode of the first diode is connected to the anode of the second diode, the cathode of the second diode is connected to the first end of the fifth capacitor, the first end of the fifth capacitor is also connected to the first end of the twelfth resistor, the second end of the eleventh resistor is connected to the second end of the fifth capacitor, wherein the first end of the eleventh resistor is connected to the driving current, the first end of the fifth capacitor is connected to the power supply voltage, and the first end of the eleventh resistor and the second end of the twelfth resistor are connected to the driving module.

8. A control method applied to the valve positioner drive circuit according to any one of claims 1 to 7, characterized in that, It includes: obtaining a driving signal and a power supply control signal; signal conversion is performed on the valve position control signal in the driving signal to obtain a driving current, so as to drive the valve positioner based on the driving current; when the valve positioner changes, the power supply voltage of the driving module is switched from a first voltage to a second voltage based on the power supply control signal, wherein the second voltage is greater than the first voltage.

9. The control method of a valve positioner drive circuit according to claim 8, characterized by, Signal conversion is performed on the valve position control signal to obtain a driving current, including: under the control of a clock signal and a chip select signal in the driving signal, the valve position control signal is converted into an analog voltage signal; voltage-current conversion is performed on the analog voltage signal to obtain the driving current.

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