Method and system for operating an actuator - Patents.com

Abstract

An actuator for a flow control valve includes an electric motor (112) for driving an output shaft connected to the valve, a power source (128) having a characteristic defining a desired direction of drive of the electric motor, a sensor (132) for detecting the characteristic, a connector (134) for connecting the current source to the electric motor, and a control system (130) configured to connect the power source to the electric motor. Operations of the actuator include providing a current, detecting the characteristic, determining a desired direction of drive of the electric motor from an output of the sensor indicative of the characteristic of the current, determining that a predetermined condition does not exist that prohibits operation of the electric motor in the desired direction of drive of the electric motor, and manipulating the connector to connect the power source to the electric motor.

Description

[Technical field]

[0001] The present invention relates to a method and system for operating an actuator, such as those used to operate a valve or damper or the like. [Background technology]

[0002] Actuator valves are found in many industries. Complex installations such as those found on oil and gas installations may contain many such actuators. They are often remotely operated from a confined area of ​​the installation, and open and close on command. In one known system, control of the actuators has been achieved by changing the three-phase power supply used to power the motor that operates the actuator. For example, Rotork's A-range actuators (https: / / www.rotork.com / uploads / documents-versions / 2875 / 1 / pub003-001-00_0401.pdf) operate by changing the phase sequence (also called "phase rotation") of a three-phase supply. An operator commands a given actuator with a given phase sequence of the three-phase supply. The actuator is manually set at installation or set-up so that the motor drives in a given direction. The operator can quickly reverse this direction by reversing two of the three phases.

[0003] In more advanced types of actuators, an electronic control system can be included with the actuator. However, such systems typically require a separate control circuit in addition to the three-phase power supply. Rotork's AWT SynchroPAK series (https: / / www.rotork.com / uploads / documents-versions / 21705 / 1 / pub005-002-00_0715.pdf) is one example. In this product, a control system is provided between the three-phase power supply and the motor. The control system has a separate control circuit input that is used as an input to the control system to control the operation of the actuator. The control system is configured to determine the drive direction of the motor to open and close the valve, and the control system ensures that the phase sequence applied to the motor is correct for that direction regardless of the phase sequence provided to the actuator. Thus, even if the phase sequence provided to the actuator changes during opening and closing operations, or is constant throughout all operations, the control system ensures that the motor will operate in the desired direction. Such actuators are not compatible with control from a three-phase supply.

[0004] It is an object of the present invention to provide an actuator with an electronic control system that can operate inversely compatible with a three-phase control system, or more broadly, to allow the power supply for the motor to be used to control the direction of the motor. Summary of the Invention

[0005] One aspect of the invention is a method of operating an actuator, such as a flow control valve, the actuator comprising: an electric motor for driving an output shaft connected to the flow control valve; a power source for powering the electric motor, the power having characteristics that define a desired direction of drive of the electric motor; A sensor for detecting the characteristic; an operable connector for connecting a power source to the electric motor; a control system configured to operate the connector to connect a power source to the electric motor; The method comprises: Powering the power source; using a sensor to detect a characteristic of the power; determining, using a control system, a desired direction of drive of the electric motor from an output of a sensor characteristic of the power; using a control system to determine whether the actuator meets a set of predetermined operating conditions for operating the electric motor in a desired direction, and inhibiting operation of the electric motor if the actuator does not meet any of the set of predetermined operating conditions; and manipulating the connector using a control system to connect power to the motor.

[0006] Another aspect of the invention includes an actuator, such as a flow control valve, comprising: an electric motor for driving an output shaft connected to the flow control valve; a power source for powering the electric motor, the power having characteristics that define a desired direction of drive of the electric motor; A sensor for detecting the characteristic; an operable connector for connecting a power source to the electric motor; a control system configured to operate the connector to connect a power source to the electric motor; This control system is determining a desired direction of drive of the electric motor from an output of a sensor characteristic of the power; Determining whether the actuator complies with a set of predetermined operating conditions for operating the electric motor in a desired direction; inhibiting operation of the electric motor if the actuator does not comply with any of a set of predetermined operating conditions, or The actuator is configured to operate the connector to connect the power source to the electric motor when the actuator meets a set of predetermined operating conditions for operating the electric motor in a desired direction.

[0007] The signals to start and indicate the direction of drive of an electric motor can be provided through the power supply without the need for a separate control circuit with associated wiring, so the direction of operation of the motor can be controlled simply by controlling the characteristics of the power supply.

[0008] The power source may be a three-phase source. The electric motor may be a three-phase motor. In this case, the characteristic is the phase sequence in the three-phase source. The connector may be configured such that changing the phase sequence of the three-phase source reverses the drive direction of the electric motor. Other sources of power, such as single-phase sources or DC sources, and electric motors may also be used. In such cases, the characteristic may be a signal applied to the power source, such as a modulation or other change in the power source that can be detected by the actuator. The characteristic may relate to voltage, current, or phase, depending on the particular nature of the power source used.

[0009] The term "connector" can include mechanical (electromechanical) connections, electronic connections, or electric / electronic motor controllers, depending on the nature of the particular electric motor, power source, and control system used.

[0010] The predetermined set of operating conditions may include a condition related to a desired direction of operation. For example, the actuator may further include a position sensor arranged to output a signal indicative of the position of the output shaft. In this case, the control system may be configured to determine whether the position of the output shaft is equal to or less than a predetermined limit of rotation in a predetermined direction, and to inhibit operation of the connector if the desired driving direction of the electric motor would rotate the output shaft in the predetermined direction beyond the predetermined limit position. After operating the connector to connect a power source to the electric motor and rotating the electric motor in the predetermined direction, if the position sensor outputs a signal indicating that the output shaft has reached the predetermined limit of rotation in the predetermined direction, the control system may be configured to operate the connector to disconnect the power source from the electric motor. For example, this may be useful to prevent damage to the actuator or valve from continuing to operate the electric motor when the valve has reached a fully open or fully closed position relative to a physical stop or limit.

[0011] The actuator may further include a torque sensor arranged to measure the output of the actuator, e.g., the torque of the output shaft. In this case, the control system may be configured to determine whether the torque is at a predetermined limit for rotation in a predetermined direction and to inhibit operation of the connector if the desired drive direction of the electric motor is in the predetermined direction and the torque would exceed the predetermined limit. After operating the connector to connect a power source to the electric motor and rotating the electric motor in the predetermined direction, the control system may be configured to operate the connector to disconnect the power source from the electric motor when the torque sensor outputs a signal indicating that the torque has reached the predetermined limit of rotation in the predetermined direction. For example, this may be useful to prevent damage to the actuator or valve from continuing to operate the electric motor when the valve has reached a fully open or fully closed position against a physical stop or limit, or is blocked from further movement due to a jam or the like.

[0012] The predetermined set of operating conditions for the electric motor may also include conditions unrelated to the desired direction of motion, such as motor temperature not exceeding a predetermined level, detection of a power supply change beyond a predetermined level, detection of sensor errors, and detection of control system failures.

[0013] The control system may be configured to generate a position indicating signal indicative of the position of a valve mounted on the output shaft and to use the position indicating signal to generate an indication of position external to the actuator.

[0014] Another aspect of the invention includes a system comprised of a series of actuators and a control station, each actuator connected by a power supply to the control station, which includes a central control system for individually selecting the characteristics of the power supply for each actuator, the only point of contact between the control station and the control system for each actuator being the power supply.

[0015] Other aspects of the invention will be apparent from the specification. [Brief description of the drawings]

[0016] [Figure 1] FIG. 1 is a top view of a known actuator.

[0017] [Diagram 2] FIG. 2 is a side view of the actuator of FIG.

[0018] [Diagram 3] FIG. 2 is a schematic diagram of a control system for the actuator of FIG. 1.

[0019] [Figure 4] 2 is a schematic diagram of an actuator according to an embodiment of the present invention.

[0020] [Diagram 5]FIG. 1 is a schematic diagram of a system including multiple actuators, according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] explanation 1 and 2 are top and side views of a known type of actuator that can be used to operate a valve (or damper, or other device). The actuator includes a housing 10 containing a three-phase electric motor 12, a switch mechanism 14, and a connection to a power source 16. A shaft 18 extends through the housing and is driven in rotation by the motor 12. A valve (not shown) is connected to the shaft 18, either directly or through a gearbox. The electric motor 12 drives the shaft with a worm drive. Reversing the direction of the motor reverses the direction of rotation of the shaft 18. The shaft is provided with a hand wheel 20 for manually operating the actuator in the event of a motor failure, and a lever 22 for engaging and disengaging the hand wheel 20 from the shaft 18. A position indicator 24 is provided at the end of the switch mechanism 14, and a local control selector 26 is provided at the power connection 16.

[0022] Figure 3 is a schematic diagram of the control system of the actuator of Figures 1 and 2. A three-phase power supply 28 is connected via the power supply 16, which includes a motor control 30 that powers the motor 12 (the motor control 30 is shown outside the housing 10, but is actually housed within the power supply 16). The motor control 30 determines the driving direction of the motor 12 according to the phase sequence of the three-phase power supply. To operate the actuator in a given direction, the operator determines a given phase sequence of the three-phase power supply for the actuator. To change the driving direction of the actuator, the operator changes the sequence of two phases in the three-phase power supply. In response to the changed phase sequence, the motor control 30 drives the motor 12 in the opposite direction. The cable providing the three-phase power supply is the only connection to provide operating power and operating instructions from a remote location to the actuator.

[0023] 1, 2 and 3, the motor 12 begins operation as soon as power is applied to the power supply 28. An electromechanical switch can be used to stop the motor when the valve reaches a limit position. Protecting the actuator, and especially the motor, from damage relies on proper installation and configuration of the switch.

[0024] The basic structure of the actuator according to the present invention is the same as that shown in Figures 1 and 2, but the electronic circuitry of the power supply and the way it operates are different. As in the embodiment of Figures 1 and 2, the three-phase cable is the only connection to the actuator, allowing operating power and instructions to reach the actuator from a remote location.

[0025] 4 is a schematic diagram of a control system for an actuator according to one embodiment of the invention. As previously mentioned, the actuator includes a three phase electric motor 112 powered by a three phase power supply 128. A control system 130 includes a phase detector 132 and a connector in the form of a switching unit 134. When the actuator is powered, the phase sequence of the three phase power supply is sensed by the phase detector system 132. The phase detector system 132 is provided with a preset logic that defines the desired direction of rotation of the motor depending on the phase sequence.

[0026] The switching section 134 includes two configurable switches C1, C2. In a first configuration, switch C1 is open and switch C2 is closed, and the phases of the three-phase power supply are connected to the motor 112 in the same order as the power supply. In a second configuration, switch C2 is open and switch C1 is closed, and the order of the two phases of the three-phase power supply is reversed. When not in operation, both switches C1, C2 are open, i.e. the motor 112 is not powered. Only one of the switches C1, C2 can be closed at a time. In another embodiment, the switching section is electronic and can thereby form part of an electronic motor drive.

[0027] The particular direction of drive for the motor 112 for a given phase sequence, and whether this translates to opening or closing a valve attached to the actuator, is determined when the actuator is initially set up. Prior to configuring the switching portion 134, the control system 130 detects when the three-phase power source 128 is energized and that no conditions have been found that would prevent movement of the actuator in the desired direction.

[0028] In this manner, when the switching element 134 is in the first configuration, the motor will operate in a given direction determined by the phase sequence of the power source as long as power is provided via the three-phase power source 128. Changing the phase sequence during operation will cause the motor 112 to reverse direction from its original direction.

[0029] The control system 130 includes a number of sensor inputs that prevent or cease operation if certain conditions exist. The system 130 includes a monitoring relay 138 that provides a motor stationary signal that prevents power from being applied to the motor by the switching element 134. This inhibits operation of the motor 112 to avoid damage to the actuators, particularly the motor.

[0030] Some of the conditions that inhibit motor operation may be applied regardless of the desired direction of movement of the motor 112. The motor 112 includes a thermostat 136. When the temperature in the motor windings exceeds a predetermined level, the thermostat trips and power to the motor is inhibited by a monitoring relay 138. Other immobilization signals that may cause the motor to be immobilized by the monitoring relay 138 include a signal from a phase detection system indicating loss of a phase in the three-phase power supply, detection of an error in a position sensor (e.g., an encoder) 140 connected to the actuator shaft, and detection of a fault in the control system 130.

[0031] Depending on the motor drive direction, there are other conditions that may prohibit motor operation. For example, if the valve is fully open or fully closed, further movement in the open or closed direction may cause damage to the actuator or the valve. However, movement in the reverse direction (i.e. from open to closed or closed to open) may be permitted.

[0032] The actuator includes a position sensor 140, for example on the actuator output shaft. If this sensor indicates that the valve is at a limit position, motor operation can be inhibited by the control system 130 when the phase detector 132 indicates that the desired direction of movement of the motor 112 is to drive the valve further towards the limit position. If the desired direction is to drive the valve away from the limit position, motor operation is not inhibited. The position sensor 140 can also be used to indicate when motor operation should be stopped due to the valve reaching a limit position.

[0033] The actuator also includes a torque sensor 142, for example to detect the torque at the output of the actuator. This torque is affected by resistance to the movement of the valve (or any other factor inside the valve or actuator, e.g. internal blockage, acting against the motor's efforts to turn the valve). Thus, when the valve reaches a limit position, the torque rises and prevents further movement in the same direction. In such a case, the control system prohibits the motor 112 from moving in a given direction, but allows it to move in the opposite direction. As with the limit positions, even if the valve is not at the limit position, the torque may rise due to something that prevents the valve from moving further in the given direction. In this situation, the output of the torque sensor 142 can also be used to stop the operation of the motor 112.

[0034] If the input power source indicates that the desired direction of motion is toward a limit or obstacle, then a direction-based inhibition is provided in which the control system operates switching element 134 to prevent power source 128 from being connected to motor 112, using position sensor 140 and / or torque sensor 142. However, if motion is away from the limit or obstacle location, there is no action.

[0035] The control system 130 includes a number of intermediate position switches S1-S4 that can be configured to open and close relays at any predetermined intermediate travel position of the actuator (ie, positions other than fully open or fully closed).

[0036] The phase sequence of the input power supply is detected by the control system phase detection system 132, which determines the direction of motor movement by the control system 130. This determined direction can be used in conjunction with the output of the position encoder 140 to generate a signal indicating the direction of movement of a valve attached to the actuator.

[0037] The actuator may also include a local control selector 126 and a position indicator 124, visible from the exterior of the housing. The valve position and direction output from the control system may be displayed on the indicator 124. A battery 144 is also provided to maintain functionality of the electronics when three phase power is not present.

[0038] FIG. 5 shows a schematic diagram of a system using the actuators described above. Such a system may be an oil or gas facility with multiple valves or actuators distributed over a wide area. The system includes a control station 200 having a central control system 202 operated by an operator. The central control system 202 is connected to the actuators 204a-d by a power cable 206. In use, the central control system 202 is configured to provide three-phase power to specific valves. A phase rotation of the power supply is selected to drive the motor of each actuator in a specific direction. Each actuator 204a-d can be operated independently of the others. Furthermore, whether a given phase rotation results in one drive direction or the other, or whether it causes a valve to open or close, depends on how the specific actuator is installed and configured. The power cable 206 is the only direct connection between the central control system 202 and the individual actuators 204a-d.

[0039] Various modifications can be made within the scope of the present invention. Although a three-phase motor and power supply have been described above, the same concepts can be applied to other motor topologies and power supplies, such as DC power supplies, using a characteristic of the power supply that sets the drive of the motor to operate in a given direction. This characteristic can be, for example, a signal superimposed on the current supply.

Claims

1. 1. A method of operating an actuator for a flow control valve or the like, comprising: an electric motor for driving an output shaft connected to the flow control valve; a power source for powering the electric motor, the power having a characteristic that defines a desired drive direction of the electric motor; a sensor for detecting said characteristic; an operable connector for connecting the power source to the electric motor; a control system configured to operate the connector to connect the current source to the electric motor; The method further comprising: powering the power source; using the sensor to detect the characteristic of the power; Using the control system, determining the desired direction of drive of the electric motor from an output of the sensor indicative of the characteristic of the power; determining whether the actuator complies with a set of predetermined operating conditions for operating the electric motor in the desired direction; inhibiting operation of the electric motor if the actuator does not comply with any of the set of predetermined operating conditions; or and manipulating the connector to connect the power source to the electric motor when the actuator meets the set of predetermined operating conditions for operating the electric motor in the desired direction.

2. The method of claim 1 , wherein the power source is a three-phase power source.

3. The method of claim 2 , wherein the electric motor is a three-phase motor.

4. 4. The method of claim 2 or 3, wherein the characteristic is a phase sequence in the three-phase power supply.

5. 5. The method of claim 4, further comprising changing the phase sequence of the three-phase power source to reverse the desired drive direction of the electric motor.

6. The method of claim 1 , wherein the power source is a single phase power source.

7. The method of claim 1 , wherein the power source is a DC power source.

8. 8. The method of claim 1, wherein the actuator further comprises a position sensor configured to output a signal indicative of a position of the output shaft.

9. determining, using the control system, whether the position of the output shaft is at a limit of rotation in a predetermined direction; prohibiting operation of the connector if the desired driving direction of the electric motor is to rotate the output shaft in the predetermined direction beyond the limit position. The method of claim 8 further comprising:

10. 9. The method of claim 8, wherein manipulating the connector to connect the power source to the electric motor causes the electric motor to rotate in a predetermined direction, the method further comprising using the control system to manipulate the connector to disconnect the power source from the electric motor when the position sensor outputs a signal indicating that the output shaft has reached a rotation limit in the predetermined direction.

11. The method of claim 1 , wherein the actuator further comprises a torque sensor configured to measure a torque at an output of the actuator.

12. using the control system to determine whether the torque is at a predetermined limit for rotation in a predetermined direction; prohibiting operation of the connector if the desired drive direction of the electric motor is in the predetermined direction and results in a torque exceeding the predetermined limit. The method of claim 11 further comprising:

13. 12. The method of claim 11, further comprising: manipulating the connector to connect the power source to the electric motor, thereby rotating the motor in a predetermined direction, the method further comprising using the control system to manipulate the connector to disconnect the power source from the electric motor when the torque sensor outputs a signal indicating that the torque has reached a rotation limit in the predetermined direction.

14. when the temperature of the electric motor exceeds a predetermined level; when it is detected that the change in the power supply exceeds a predetermined level; When a sensor error is detected, When a fault in the control system is detected 14. The method of claim 1 , further comprising generating a signal to inhibit operation of the electric motor when the control system detects at least one of the following conditions:

15. generating a position indicating signal at the control system indicative of a position of a valve mounted on the output shaft; using said position indicating signal to generate an indication of said position external to said actuator; 15. The method of claim 1, further comprising:

16. An actuator, such as a flow control valve, comprising: an electric motor for driving an output shaft connected to the flow control valve; a power source for powering the electric motor, the power having a characteristic that defines a desired drive direction of the electric motor; a sensor for detecting said characteristic; an operable connector for connecting the power source to the electric motor; a control system configured to operate the connector to connect the power source to the electric motor; The control system comprises: determining whether the actuator complies with a set of predetermined operating conditions for operating the electric motor in the desired direction; inhibiting operation of the electric motor if the actuator does not comply with any of the set of predetermined operating conditions; or an actuator configured to operate the connector to connect the power source to the electric motor when the actuator meets the set of predetermined operating conditions for operating the electric motor in the desired direction.

17. The actuator of claim 16 , wherein the power source is a three-phase power source.

18. 20. The actuator of claim 17, wherein the electric motor is a three-phase electric motor.

19. 19. An actuator according to claim 17 or 18, wherein the characteristic is a phase sequence in the three-phase power supply.

20. 20. The actuator of claim 19, wherein the connector is configured such that changing the phase sequence of the three-phase power source reverses the drive direction of the electric motor.

21. The actuator of claim 16 , wherein the power source is a single phase power source.

22. The actuator of claim 16 , wherein the power source is a DC power source.

23. 23. The actuator of any one of claims 16 to 22, further comprising a position sensor configured to output a signal indicative of a position of the output shaft.

24. determining whether the position of the output shaft is at a predetermined limit for rotation in a predetermined direction; 24. The actuator of claim 23, wherein the control system is configured to inhibit operation of the connector if the desired drive direction of the electric motor would cause an output shaft to rotate in the predetermined direction beyond the predetermined limit position.

25. 24. The actuator of claim 23, wherein the control system is configured to operate the connector to connect the power source to the electric motor to rotate the motor in a predetermined direction and then operate the connector to disconnect the power source from the electric motor when the position sensor outputs a signal indicating that the output shaft has reached a predetermined limit for rotation in the predetermined direction.

26. 26. An actuator according to any one of claims 16 to 25, further comprising a torque sensor arranged to measure torque at an output of the actuator.

27. determining whether the torque is at a predetermined limit for rotation in a predetermined direction; 27. The actuator of claim 26, wherein the control system is configured to inhibit operation of the connector if the desired drive direction of the electric motor is in the predetermined direction and results in a torque that exceeds the predetermined limit.

28. 27. The actuator of claim 26, wherein the control system is configured to operate the connector to connect the power source to the electric motor to rotate the electric motor in a predetermined direction and then operate the connector to disconnect the power source from the electric motor if the torque sensor outputs a signal indicating that the torque has reached a predetermined limit for rotation in the predetermined direction.

29. when the temperature of the electric motor exceeds a predetermined level; when it is detected that the change in the power supply exceeds a predetermined level; When a sensor error is detected, When a fault in the control system is detected 29. An actuator as claimed in any one of claims 16 to 28, wherein the control system is configured to inhibit operation of the electric motor under at least one of the following conditions:

30. The control system comprises: generating a position indicating signal indicative of a position of a valve mounted on said output shaft; 30. An actuator according to any one of claims 16 to 29, configured to use the position indicating signal to generate an indication of the position external to the actuator.

31. 31. A system comprising a series of actuators according to any one of claims 16 to 30 and a control station, each of said actuators being connected to said control station by said power source, and said control station including a central control system for individually selecting said characteristics of said power sources for each of said actuators.

32. 32. The system of claim 31, wherein, for each of said actuators, said power source is the only point of contact between said control station and said control system.

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