阅读说明：本技术 用于优化控制回路系统中马达驱动的装备的使用的电子设备及方法 (Electronic device and method for optimizing the use of motor-driven equipment in a control loop system ) 是由 W·R·布兰克梅尔 M·P·汤普森 于 2020-04-10 设计创作，主要内容包括：一种利用包括机组的控制回路系统实施的设备和方法,其中,机组包括工作机、驱动工作机的电动马达和最终控制元件,并且其中,设备和方法优化工作机的状态以使马达的功耗最小化并且使机组的可靠性最大化。(An apparatus and method implemented with a control loop system including an assembly, wherein the assembly includes a work machine, an electric motor driving the work machine, and a final control element, and wherein the apparatus and method optimizes a state of the work machine to minimize power consumption of the motor and maximize reliability of the assembly.)

1. An apparatus for optimizing the state of an assembly, wherein the assembly comprises a working machine, an electric motor driving the working machine and a final control element, and wherein the assembly is mounted in a control loop system for which a process controller controls a process variable at a set point by adjusting the position of the control element using a feedback signal, the apparatus comprising:

at least one sensor that measures at least one physical characteristic of the unit, including acceleration, speed, temperature, power, torque, voltage, current, frequency, pressure, flow, or velocity;

at least one computer system comprising a processor, a memory storing data and computer-executable instructions, hardware in communication with the at least one sensor, and program instructions storing at least one input data set acquired from the at least one sensor into the memory;

a set of characterization data stored in the memory of the at least one computer system, the set of characterization data describing at least some physical characteristics, operational behavior, and allowable operating ranges of the crew and the control loop system;

a controller in communication with the at least one computer system, the controller controlling a speed of the electric motor; and is

Wherein the device estimates the state of the aggregate and estimates the setpoint using the characteristic data set and the at least one input data set, implements an optimization method that seeks to minimize power consumption of the electric motor and maximize reliability of at least the working machine, determines a target state that can be reached and is contained within the allowable operating range by adjusting a speed of the electric motor to be consistent with the setpoint, and controls the speed of the electric motor to reach the target state.

2. The apparatus of claim 1, wherein the working machine is a pump and the final control element is a modulating control valve.

3. The apparatus of claim 2, wherein the pump is a rotodynamic pump.

4. The apparatus of claim 1, wherein the working machine is a fan or blower and the final control element is a damper.

5. The apparatus of claim 1, wherein the optimization method implemented by the apparatus seeks to minimize power consumption of the electric motor, maximize reliability of the working machine, and maximize reliability of the electric motor.

6. The apparatus of claim 1, wherein the optimization method implemented by the apparatus seeks to minimize power consumption of the electric motor, maximize reliability of the working machine and maximize reliability of the final control element.

7. The apparatus of claim 1, wherein the optimization method implemented by the apparatus seeks to minimize power consumption of the electric motor, maximize reliability of the working machine, maximize reliability of the electric motor, and maximize reliability of the final control element.

8. The apparatus of claim 1, wherein the optimization method implemented by the apparatus comprises assigning a value to electric motor power consumption and assigning a value to at least reliability of the working machine, wherein the assigned values are expressed in common units or unitless, a total value is a mathematical combination of the values, and the optimization method maximizes or minimizes the total value.

9. The apparatus of claim 1, wherein the electric motor is configured to receive AC power.

10. The apparatus of claim 1, wherein the electric motor is configured to accept DC power.

11. The device of claim 1, wherein the feature data set is preprogrammed into the memory, configured during setup, learned during operation, or obtained through a combination thereof.

12. The apparatus of claim 1 wherein the controlled process variable is flow rate.

13. The apparatus of claim 1 wherein the process variable being controlled is pressure.

14. A method for optimizing the state of an assembly, wherein the assembly comprises a working machine, an electric motor driving the working machine and a final control element, and wherein the assembly is installed in a control loop system for which a process controller controls a process variable at a set point by adjusting the position of the final control element using a feedback signal, the method comprising:

obtaining an input data set comprising at least one variable measured by at least one sensor measuring at least one physical characteristic of the unit, the at least one physical characteristic comprising acceleration, speed, temperature, power, torque, voltage, current, frequency, pressure, flow or velocity;

using the input data set and a characteristic data set to approximate a state of the unit, the characteristic data set describing at least some physical characteristics, operational behavior, and allowable operating ranges of the unit and the control loop system;

estimating a setpoint of the control loop system from a state of the unit;

utilizing the characteristic data set and the set point to generate at least one correlation function defining an expected range of the at least one input data set over a range of allowable work machine and electric motor speeds;

determining a set of multiple possible states at the set point and contained within an allowable operating range of the crew as defined within the feature data set;

performing an optimization procedure seeking to minimize power consumption of the electric motor and maximize reliability of at least the work machine to determine a target state from the set of multiple possible states;

changing the electric motor speed toward the target state by at least one speed change increment until the target state is reached; and

obtaining at least one input data set after each of the at least one rate change increment, and verifying that the at least one input data set is contained within an expected range of the at least one input data set as defined by the at least one correlation function at the rate of change.

15. The method of claim 15, wherein if the at least one input data set acquired after each of the at least one rate change increment is not verified by the at least one correlation function, the at least one rate change increment is undone, the feature data set is modified, and the method is repeated.

16. The method of claim 15, wherein the work machine is a pump and the final control element is a modulating control valve.

17. The method of claim 17, wherein the pump is a rotodynamic pump.

18. The method of claim 15, wherein the work machine is a fan or blower and the final control element is a damper or a variable inlet vane system.

19. The method of claim 15, wherein the method seeks to minimize power consumption of the electric motor, maximize reliability of the working machine, and maximize reliability of the electric motor.

20. The method of claim 15, wherein the method seeks to minimize power consumption of the electric motor, maximize reliability of the working machine and maximize reliability of the final control element.

21. The method of claim 15, wherein the method seeks to minimize power consumption of the electric motor, maximize reliability of the working machine, maximize reliability of the electric motor, and maximize reliability of the final control element.

22. The method of claim 15, wherein the method comprises assigning a value to electric motor power consumption and assigning a value to at least reliability of the work machine, wherein the assigned values are expressed in common units or unitless, a total value is a mathematical combination of the values, and the method maximizes or minimizes the total value.

23. The method of claim 15, wherein the electric motor is configured to receive AC power.

24. The method of claim 15, wherein the electric motor is configured to accept DC power.

25. The method of claim 15, wherein the feature data set is pre-programmed into the memory, configured during setup, learned during operation, or obtained through a combination thereof.

26. The method of claim 15, wherein the controlled process variable is flow rate.

27. The method of claim 15, wherein the controlled process variable is pressure.

Technical Field

The present invention relates generally to industrial process control loop systems and, more particularly, to an apparatus and method for optimizing the state of a control loop assembly including an electric motor, a work machine and a final control element installed in the control loop system.

Background

A control system for industrial process applications comprises a number of control loops which themselves comprise physical and logical components necessary to perform the following four functions: 1) providing hydraulic energy or pneumatic energy for the system in the form of pressure and flow; 2) measuring a process variable such as flow, pressure or temperature; 3) comparing the process variable measurement to a process variable set point; and 4) adjusting the final control element to force the process variable toward the process variable set point.

A first type of prior art control circuit may include an electric motor, a work machine (such as a pump or fan driven by the electric motor at a fixed rate), and a final control element (such as a modulating control valve or damper in fluid communication with the work machine). The control loop further includes at least one feedback sensor to measure a process variable such as flow, pressure or temperature, the at least one feedback sensor being in communication with a controller such as a Distributed Control System (DCS) or Programmable Logic Controller (PLC) or a transmitter that receives and conditions signals from the sensor and then transmits the conditioned signals to the controller. The controller receives a process variable measurement, compares the measurement to a specified process variable set point, and outputs a signal to adjust the final control element in an attempt to maintain the process variable at the specified set point. In industrial process applications, the controller may implement well known control methods, such as Proportional Integral Derivative (PID) control.

Each machine in the control loop assembly may be evaluated for reliability, which is referred to as the ability of the machine to maintain performance throughout its useful life. Thus, reliability degradation is associated with unplanned maintenance, unplanned production downtime, and shortened service life. The costs associated with maintenance, down time and power consumption are often the most significant factors in the control loop plant life cycle costs. For these reasons, the goal of maximizing reliability and minimizing power consumption while meeting system requirements provides the greatest benefit to the user.

The first type of prior art control loop is most common in industrial process applications and is considered to be a reliable and easily understood technique. The final control element is used to provide accurate process variable control over a wide range of process variables with a variety of available valve types and control characteristics. However, the first type of prior art control loop suffers from well-known disadvantages. For example, improper sizing, which often results from intentional oversizing of the work machine, often results in the work machine operating away from the Best Efficiency Point (BEP), which reduces the efficiency and reliability of the work machine, while proper sizing reduces the flexibility of the system to accommodate future system or set point changes. Further, incorrect sizing may force the final control element to operate in a position that reduces the reliability and reduces controllability of the final control element. Also, since the working machine is driven to provide a greater pressure or flow rate than is required to maintain the set point, a large excess of power is consumed. Furthermore, the electric motor and the working machine must drive a larger load and at a faster rate than is required to maintain the set point, thereby reducing the reliability of the electric motor and the working machine.

Similarly, a second type of prior art control loop may include an electric motor, a work machine, at least one sensor, and a controller, but no separate final control element is present in the control loop. Instead, the controller output is directed to an Adjustable Speed Drive (ASD) that attempts to maintain the process variable at a specified set point by adjusting the electric motor speed. In practice, the controller may be integrated with the ASD.

The second type of prior art control loop has several advantages over the first type of prior art control loop. The known working machines are usually driven at a lower rate and therefore consume less energy overall than the first type of prior art control loop. Further, it is known to run at a lower rate, thereby improving the reliability of the electric motor and the working machine as a whole. In addition, no separate end-of-life control element life cycle cost is incurred. However, the second type of prior art control loop suffers from well-known disadvantages. For example, process variable control by adjusting the rate is less accurate than the first type of prior art control loop and, importantly, does not provide a reliable shut down. Further, process variable control by adjusting the rate may not be able to be maintained over a wide operating range because the motor may not cool adequately at low rates and power consumption may increase at low rates due to reduced efficiency. Also, systems with high static head may force the work machine to operate away from the BEP, which reduces the efficiency and reliability of the work machine. Furthermore, switching from a first type of prior art control loop to a second type of prior art control loop introduces new risks and requires expensive analysis and engineering of the physical system and control logic.

Us patent No. 7,925,385(Stavale) attempts to address the disadvantages in the prior art control loop by using an ASD with a first type of prior art control loop in a specific way. Stavale achieves some of the advantages of the prior art control loops of the first and second types, however, Stavale has additional disadvantages.

For example, in a control loop with a flow rate process variable, Stavale cannot evaluate the valve position and proximity of the working machine to the BEP. In contrast, Stavale assumes that the optimal valve position and work machine speed will occur at as little of a rate as possible at which the process variable set point can be achieved, which is not necessarily accurate. Furthermore, if the minimum allowable rate is not reached, Stavale needs to temporarily fully open or temporarily fully close the modulating control valve, thereby losing the ability to control the process variable and interrupting the process. Also, in a control loop with pressure process variables, Stavale cannot evaluate valve position and work machine speed. In contrast, Stavale assumes that the optimal valve position and work machine speed will occur between 90% and 110% of the BEP flow rate, which is not necessarily accurate. Further, Stavale does not take into account power consumption in the optimization process. It is used only for determining the reference data. For certain motor types (such as induction motors, which are most common in industrial process applications), it is known that efficiency drops dramatically as the load decreases. Thus, operating at the lowest possible load is not necessarily equivalent to minimizing power consumption. In summary, Stavale cannot effectively optimize the state of a control circuit plant including an electric motor, a working machine, and a final control element installed in a control circuit system.

U.S. patent No. 7,797,062(Discenzo) attempts to address the shortcomings in prior art control loops by adjusting a process variable within an allowable range around a set point to achieve one or more control system objectives such as efficiency, component life expectancy or safety. In particular, Discenzo identifies an act of changing an operating rate of at least one machine as a means of adjusting performance. However, Discenzo has several disadvantages.

Discenzo does not teach optimization within a control loop in which a controller seeks to maintain a discrete process variable set point. In contrast, Discenzo requires that process variables be permitted to move within a range around a set point. The extent to which the control loop can be optimized according to Discenzo depends on the size of the tolerance range. The range may be narrow since it is related to the output of a single control loop. Discenzo is not effective in optimizing the state of a control loop assembly comprising an electric motor, a working machine and a final control element installed in a control loop system.

Disclosure of Invention

The present invention addresses the shortcomings in prior art control loop systems by providing an apparatus and method that is implemented in conjunction with a first type of prior art control loop system that includes a work machine, an electric motor that drives the work machine, and a final control element, referred to herein as a unit, wherein the apparatus and method optimizes the state of the unit to minimize power consumption by the motor and maximize reliability of the unit. It should be understood that the state of the unit includes the collective operating conditions of the unit components. It can be said that the apparatus and method operate independently of the process controller of the control loop system because the implementation does not require physical changes to the control loop system, logical changes to the process controller, or communication with the process controller or the control loop feedback instrument. Instead, the device is installed in the power supply of the motor and has the hardware necessary to change the power supply in order to control the motor speed. Similarly, the method would be implemented with a device having the ability to control the motor speed at this location.

In a first aspect, the disclosure provides a device for optimizing the state of an assembly, wherein the assembly comprises a working machine, an electric motor driving the working machine and a final control element, and wherein the assembly is mounted in a control loop system for which a process controller controls a process variable at a set point by adjusting the position of the control element using a feedback signal. The apparatus comprises: at least one sensor that measures at least one physical characteristic of the unit, the at least one physical characteristic including acceleration, speed (velocity), temperature, power, torque, voltage, current, frequency, pressure, flow or velocity (speed); and at least one computer system including a processor, a memory storing data and computer-executable instructions, hardware in communication with the at least one sensor, and program instructions to store the at least one input data set acquired from the at least one sensor in the memory. The apparatus further includes a feature data set stored in the memory of the at least one computer system, the feature data set describing at least some physical characteristics, operational behavior, and allowable operating ranges of the assembly and the control loop system, and a controller in communication with the at least one computer system, the controller controlling the speed of the electric motor. The device estimates a state of the aggregate and estimates a setpoint using the characteristic data set and the at least one input data set, implements an optimization method that seeks to minimize power consumption of the electric motor and maximize reliability of at least the working machine, determines a target state that can be reached and is contained within an allowable operating range by adjusting a speed of the electric motor to coincide with the setpoint, and controls the speed of the electric motor to reach the target state.

In a second aspect, the disclosure provides a method for optimizing the state of an assembly, wherein the assembly comprises a working machine, an electric motor driving the working machine and a final control element, and wherein the assembly is mounted in a control loop system for which a process controller controls a process variable at a set point by adjusting the position of the final control element using a feedback signal. The method comprises the following steps: obtaining an input data set comprising at least one variable measured by at least one sensor measuring at least one physical characteristic of the unit, the at least one physical characteristic comprising acceleration, speed, temperature, power, torque, voltage, current, frequency, pressure, flow or rate; and approximating the state of the unit using the input data set and a characteristic data set, the characteristic data set describing at least some physical characteristics, operational behavior and allowable operating ranges of the unit and the control loop system. The method further comprises the following steps: estimating a set point of the control loop system from a state of the unit; generating at least one correlation function using the characteristic data set and the set point, the at least one correlation function defining an expected range of the at least one input data set over a range of allowable work machine and electric motor speeds; and determining a set of multiple possible states, the set of multiple possible states being at set points and contained within an allowable operating range of the unit as defined within the feature data set. The method further comprises the following steps: performing an optimization procedure seeking to minimize power consumption of the electric motor and maximize reliability of at least the working machine to determine a target state from a set of multiple possible states; changing the electric motor speed toward the target state by at least one speed change increment until the target state is achieved; and obtaining at least one input data set after each of the at least one rate change increment and verifying that the at least one input data set is contained within an expected range of the at least one input data set as defined by the at least one correlation function at the rate of change.

It should be understood that when a change in motor speed occurs, as initiated by a device or method for reducing power consumption and improving reliability, a process variable sensor will measure the change in the process variable, and then the process controller of the control loop system will react by adjusting the final control element to move the process variable toward the set point, without regard to the device or method.

Thus, the apparatus and method of the disclosure allow the same advantages of the first type of prior art associated with the presence of the final control element, namely, accurate process control, reliable shut-down and wide process variable operating range, while overcoming the disadvantages of the first type of prior art by: adjusting the speed of the motor reduces power consumption and improves reliability of the assembly components, which reduces life cycle costs. Because the apparatus and method of the disclosure can be implemented with existing control loop systems including final control elements, retrofit applications do not require expensive analysis and engineering of the physical system and control logic. Because the set point is maintained by the final control element of the control loop system, the apparatus and method allow optimization over a greater operating range than the second type of prior art associated with controlling a process variable using motor speed. Further, the operating range is significantly larger than the prior art, which optimizes only within an acceptable process variable variation range around the set point.

The apparatus and method of the disclosure utilize an input data set comprising measurements of at least one physical characteristic of the unit and a characteristic data set describing, at least in part, the characteristics, operational behavior and allowable operating range of the unit. It will be appreciated that the input data set must have some relationship to the feature data set from which further information about the crew can be derived. Thus, the apparatus and method of the disclosure are capable of estimating the state of the crew, which enables accurate assessment of optimization criteria and provides the ability to work effectively with a variety of crew components having different characteristics.

The apparatus and method of the disclosure typically estimate the set point of the control loop system from the state of the unit under a given condition when steady state operation is detected. The apparatus and method are also capable of determining a future state based on the motor speed because the future state is consistent with this set point maintained independently by the control loop system. The correlation function utilized in the method of the disclosure describes the relationship between the expected input data set and the motor speed to enable verification that the estimated state after the speed change is consistent with the expectation. The ability of the apparatus and method to estimate future states and the verification provided by the correlation function of the method allows the present invention to select the best future state while reducing the risk of process interruption when adjusting the motor speed to reach the best future state.

Drawings

In describing the preferred embodiments, reference is made to the accompanying drawings wherein like parts bear like reference numerals and wherein:

FIG. 1 shows a first embodiment of a prior art control loop system having a throttle control configuration.

Fig. 2 shows a second embodiment of a prior art control loop system with a bypass control configuration.

Fig. 3 shows a third embodiment of a prior art control loop system having a variable speed control configuration.

Fig. 4 shows a first embodiment of an electronic device for use in a control loop system in a throttle control configuration according to the present invention.

Fig. 5 shows additional detail of the apparatus of fig. 4.

FIG. 6 shows characteristic data for an example pump.

FIG. 7 shows characterization data for an example electric motor.

FIG. 8 illustrates characterization data for an example modulating control valve.

FIG. 9 shows characterization data for an example control loop system.

Fig. 10 shows a flow chart illustrating an embodiment of a method for optimizing crew conditions according to the present invention.

FIG. 11 shows a flow chart illustrating a subroutine of the method of FIG. 10, wherein the subroutine evaluates the status of the crew.

Detailed Description

Fig. 1-3 illustrate example embodiments of prior art process control loops, and it will be understood that an understanding of these process control loops is important to properly understand and appreciate the disclosure of the present invention.

Fig. 1 illustrates a first example embodiment of a prior art control loop system (100), which is shown in a throttle control configuration. The control loop system (100) comprises: a work machine (110), which in this embodiment comprises a pump (such as a rotodynamic pump); an electric motor (120); a final control element (140) (such as a modulating control valve); a sensor (130) (such as a flow rate sensor); and a process controller (164). The unit (101) is defined as the three main machines in the control loop system (100), namely the pump (110), the motor (120) and the regulating control valve (140). The control loop system (100) further comprises: a conduit (160) connecting the pump outlet port (116) to the control valve inlet port (142); and a conduit (162) connecting the control valve outlet port (146) to the flow sensor inlet port (132).

The electric motor (120) has a shaft (122) rotatably coupled to the shaft (111) of the pump (110) to enable transmission of mechanical power. When the motor (120) receives electrical power (124), the motor shaft (122) rotates, which causes the pump shaft (111) to rotate, thereby generating a pumping action that drives a pumping flow (150) through the control loop system (100) at a flow rate (151). In this embodiment, it is understood that the provision of electrical power (124) is configured to rotate the motor shaft (122) at a fixed rate.

The pumped flow (150) enters the pump (110) through the pump inlet port (112) at a pump inlet pressure (114) and exits through the pump outlet port (116) at a pump outlet pressure (118). The pumped flow (150) continues through the conduit (160) to control valve inlet pressure (144) through the control valve inlet port (142) into the regulated control valve (140). Typically, pump outlet pressure (118) and control valve inlet pressure (144) are considered to be the same because frictional losses and height differences between them are typically minimal.

The modulating control valve (140) is the final control element in this embodiment, and it is understood that the device is equipped with an actuating valve, such as a positioner that uses the input electrical signal to control the pneumatic pressure provided to an actuator that is mechanically linked to a valve stem, wherein the pneumatic pressure is thereby applied to the valve stem to affect the position of the valve stem. As is well known to those skilled in the art, the range of movement permitted by the valve stem is referred to as the valve stroke, and the limits of this range are referred to as the fully open position and the fully closed position. The position of the valve stem at a given time may be defined in terms of percent travel. It is further known that the flow rate through and the pressure differential across the modulating control valve is a function of percent travel. Flow coefficients are commonly used to characterize the relationship between flow rate and pressure differential.

The pumped flow (150) continues through the regulated control valve (140) and exits through the control valve outlet port (146) at a control valve outlet port pressure (148). The pumped flow (150) continues through the conduit (162) into the flow sensor (130) through the flow sensor inlet (132) at the flow sensor inlet port pressure (134). Typically, the control valve outlet pressure (148) and the flow sensor inlet pressure (134) are considered to be the same because the frictional losses and height differences between them are typically minimal.

The pumped flow (150) continues through the flow rate sensor (130), exits through the flow rate sensor outlet port (136) at a flow rate sensor outlet port pressure (138), and flows to a final destination.

The flow rate sensor (130) may employ one of many flow measurement techniques known to those skilled in the art, such as those based on differential pressure, variable area, or positive displacement principles, for converting the volumetric fluid flow rate into an electrical signal. The flow rate sensor (130) may be in direct electrical communication with the controller (164) (such as illustrated in fig. 1) or alternatively in communication with a transmitter that receives and conditions a signal from the flow rate sensor (130) and transmits the conditioned signal to the controller (164).

The controller (164) is configured to control the process variable at a set point by adjusting a percent travel of the modulating control valve (140) using a feedback signal (166) from the flow sensor (130). In this embodiment, the process variable is flow rate, but in other embodiments it may be pressure, tank level, or other variable type. The controller (164) receives a feedback signal (166) from the flow rate sensor (130) and converts it to a process variable representing the flow rate (151) measured by the flow rate sensor (130). The controller (164) calculates an output signal (168) to affect the percent travel of the modulating control valve (140) using one of a number of control methods known to those skilled in the art, such as Proportional Integral Derivative (PID) control, wherein the controller (164) generally acts to maintain the process variable at the set point by moving the process variable toward the set point. The output signal (168) is received by the control valve (140), which adjusts the percent travel and thereby affects the flow rate (151) and pressure (114), (118), (144), (148), (134), (138) in the control loop system (100).

Turning to fig. 2, a prior art control loop system (200) of a second embodiment is shown in a bypass control configuration. The control loop system (200) includes a work machine, which in this case includes a rotodynamic pump (210), an electric motor (220), a final control element, which in this case is a modulating control valve (240), a pressure sensor (230), and a process controller (264). The aggregate (201) is defined as the three main machines in the control loop system (200), namely the pump (210), the motor (220) and the regulating control valve (240). The control circuit system (200) further includes a conduit (260) connecting the pump outlet port (216) to the control valve inlet port (242) and the pressure sensor inlet port (232).

The electric motor (220) has a shaft (222) rotatably coupled to a shaft (211) of the pump (210) to enable transmission of mechanical power. When the motor (220) receives electrical power (224), the motor shaft (222) rotates, which rotates the pump shaft (211), thereby creating a pumping action that drives a main pumping flow (250) through the pump (210) and into the conduit (260) at a main flow rate (251). In this embodiment, it is understood that the provision of electrical power (224) is configured to rotate the motor shaft (222) at a fixed rate.

The main pumping flow (250) enters the pump (210) through the pump inlet port (212) at a pump inlet pressure (214) and exits through the pump outlet port (216) at a pump outlet pressure (218). The main pumping flow (250) continues through the conduit (260) and is split into two flows: a forward pumping flow (252) at a forward flow rate (253) and a bypass pumping flow (254) at a bypass flow rate (255).

The forward pumped flow (252) continues through the conduit (260) and flows to the final destination. A pressure sensor (230) is in fluid communication with the forward pumping flow (252) through a pressure sensor inlet port (232) and measures a forward pumping flow pressure (234).

The bypass pumped flow (254) continues through the conduit (260) to enter the modulation control valve (240) through the control valve inlet port (242) at the control valve inlet port pressure (244) to exit through the control valve outlet port (246) at the control valve outlet pressure (248) and flow back to the supply.

Typically, the pump outlet pressure (218), the control valve inlet pressure (244), and the forward pumped flow pressure (234) are considered to be the same because the frictional losses and height differences between each are typically minimal.

Modulating the control valve (240) should be understood as being equipped with means to actuate the valve, such as a positioner that uses an input electrical signal to control the pneumatic pressure provided to an actuator that is mechanically linked to a valve stem, wherein the pneumatic pressure is thereby applied to the valve stem to affect the position of the valve stem. As is well known to those skilled in the art, the range of movement permitted by the valve stem is referred to as the valve stroke, and the limits of this range are referred to as the fully open position and the fully closed position. The position of the valve stem at a given time may be defined in terms of percent travel. It is further known that the flow rate through and the pressure differential across the modulating control valve is a function of percent travel. Flow coefficients are commonly used to characterize the relationship between flow rate and pressure differential.

The pressure sensor (230) employs one of many pressure measurement techniques known to those skilled in the art, such as those based on strain gauges, for converting static pressure into an electrical signal. The pressure sensor (230) may be in direct electrical communication with a controller (264), such as shown in fig. 2, or in direct electrical communication with a transmitter that receives and conditions a signal from the pressure sensor (230) and transmits the conditioned signal to the controller (264).

The controller (264) is configured to control the process variable at a set point by adjusting a percent travel of the modulating control valve (240) using a feedback signal (266) from the flow sensor (230). In this embodiment, the process variable is pressure, but in other embodiments it may be flow rate, tank level, or other variable type. The controller (264) receives a feedback signal (266) from the pressure sensor (230) and converts it to a process variable representing the pressure (234) measured by the pressure sensor (230). The controller (264) calculates the output signal (268) to affect the percent travel of the modulating control valve (240) using one of a number of control methods known to those skilled in the art, such as Proportional Integral Derivative (PID) control, wherein the controller (264) generally functions to maintain the process variable at the set point by moving the process variable toward the set point. The output signal (268) is received by the control valve (240), which adjusts the stroke percentage and thereby affects the flow rate (251), (253), (255) and pressure (214), (218), (234), (244), (248) in the control loop system (200).

Turning to fig. 3, a third exemplary embodiment of a prior art control loop system (300) is shown in a variable speed control configuration. The control loop system (300) includes a work machine, which in this case includes a rotodynamic pump (310), an electric motor (320), a flow rate sensor (330), a variable speed motor drive (365), and a process controller (364). The control loop system (300) further includes a conduit (360) connecting the pump outlet port (316) to the flow rate sensor inlet port (332).

The electric motor (320) has a shaft (322) rotatably coupled to a shaft (311) of the pump (310) to enable transmission of mechanical power. When the motor (320) receives electrical power (324), the motor shaft (322) rotates, which causes the pump shaft (311) to rotate, thereby generating a pumping action that drives a pumping flow (350) through the pump (310) and into the conduit (360) at a flow rate (351).

The pumped flow (350) enters the pump (310) through the pump inlet port (312) at a pump inlet pressure (314) and exits through the pump outlet port (316) at a pump outlet pressure (318). The pumped flow (350) continues through the conduit (360), enters the flow sensor (330) through the flow sensor inlet port (332) at the flow sensor inlet port pressure (334), exits through the flow sensor outlet port (336) at the flow sensor outlet pressure (338), and flows to a final destination.

Typically, the pump outlet pressure (318) and the flow sensor inlet port pressure (334) are considered to be the same because the frictional losses and height differences between them are typically minimal. The flow rate sensor (330) employs one of many flow measurement techniques known to those skilled in the art, such as those based on differential pressure, variable area, or positive displacement principles, for converting the volumetric fluid flow rate into an electrical signal.

The flow rate sensor (330) may be in direct electrical communication with the controller (364) (such as shown in fig. 3) or in direct electrical communication with a transmitter that receives and conditions a signal from the flow rate sensor (330) and transmits the conditioned signal to the controller (364).

The adjustable speed motor drive (365) employs one of many motor drive techniques known to those skilled in the art for driving an electric motor over a range of rates by adjusting the electric power (324), such as a voltage source inverter, which is typically used to control the rate of an AC induction motor by controlling the effective frequency and voltage of the electric power (324) given the input electric power (372) to the adjustable speed motor drive (365).

The controller (364) is configured to control the process variable at a set point by adjusting the speed of the motor (320) using a feedback signal (366) from the flow sensor (330). In this embodiment, the process variable is flow rate, but in other embodiments it may be pressure, tank level, or other variable type. The controller (364) receives a feedback signal (366) from the flow rate sensor (330) and converts it to a process variable representing the flow rate (351) measured by the flow rate sensor (330). The controller (364) calculates an output signal (368) for controlling the adjustable speed motor driver (365) using one of a number of control methods known to those skilled in the art, such as proportional-integral-derivative (PID) control, wherein the controller (364) generally functions to maintain the process variable at the set point by moving the process variable toward the set point. The output signal (368) is received by an adjustable speed motor drive (365) that modifies the electrical power (324) supplied to the motor (320) to adjust the speed of the motor (320) and pump (310) and thereby affect the flow rate (351) and pressures (314), (318), (334), (338) in the control loop system (300). It will be appreciated that the controller (364) may be integrated into the adjustable speed motor drive (365).

Referring now to fig. 4-11, it will be understood that the electronic devices and methods of the disclosure in general may be implemented in a wide variety of configurations. Fig. 4-11 illustrate a first preferred embodiment of the electronic device and method of the present invention configured for use with a control loop system comprising a work machine (which is a pump such as a rotodynamic pump), a final control element (such as a modulating control valve), and an electric motor operating on AC power.

In this embodiment, the control loop system is in a throttle control configuration, such as shown in the first technology control loop system (100). Fig. 4 shows the electronics (500) of the first embodiment used with a control loop system (100), which has been described in more detail previously in fig. 1. The apparatus (500) receives an input power source (402) and converts it to an output power source (404) having a voltage and frequency suitable for rotating the motor (120) at a target rate.

Fig. 5 shows the device (500) of fig. 4. The apparatus (500) includes a controller (in this case, a voltage source inverter (514)) for controlling the speed of the motor (120) by transforming an input power source (402) into an output power source (404) having a voltage and frequency suitable for rotating the motor (120) at a target speed. It will be appreciated that instead of a voltage source inverter (514), there are many other techniques known to those skilled in the art to control the speed of the motor (120).

The device (500) further comprises at least one sensor for measuring at least one physical characteristic of the aggregate (101), such as acceleration, speed, displacement, temperature, power, torque, voltage, current, frequency, pressure, flow or velocity. In this embodiment, the at least one sensor is a current sensor (516), shown in this embodiment as a component of an inverter (514), that provides a signal (518) corresponding to an input variable representing the current (404) of the output power source, the current flowing between the device (500) and the motor (120). It should be appreciated that the device (500) may include any number of sensors that measure any number of physical characteristics of the aggregate (101) in place of or in addition to the current sensor (516). The input data set (502) includes one or more input variables measured by one or more sensors. The input data set (502) may also include one or more computational variables that depend on one or more input variables. One of the input data set variables is designated as a primary input variable, and in this embodiment, the primary input variable is a calculated variable for the output power (550) of the motor (120) that depends on the current.

The apparatus (500) further includes a computer system (522) including a processor (524), memory (526), program instructions (530) stored in the memory (526), and hardware (528). It will be understood that the hardware (528) may include analog-to-digital converter integrated circuits, input/output pins on a system-on-a-chip (SoC) or microcontroller, modular data acquisition modules for use with a particular computer system, or various other devices and support components suitable for digital or analog communication with the at least one sensor (130). The computer system (522) communicates with a controller, in this embodiment a voltage source inverter (514), to control the speed of the motor (120). The hardware (528) is configured to communicate with the current sensor (516) and store the input data set (502) into the memory (526) using the program instructions (530). The computer system (522) also includes a signature data set (532) stored in the memory (526) that contains signature data describing at least some physical characteristics, operational behavior, and allowable operating ranges of the unit (101) and the control loop system (100). The feature data set (532) may be preprogrammed into the memory (526), configured during setup, learned during operation, or some combination thereof.

With respect to the characteristic data set (532) for the preferred embodiment shown in fig. 4-11, it includes the pump characteristic data set described in connection with fig. 6, the electric motor characteristic data set described in connection with fig. 7, the modulation control valve characteristic data set described in connection with fig. 8, and the control loop characteristic data set described in connection with fig. 9. It will be appreciated that the characteristic data set (532) may contain different or additional data for many different characteristics and parameters of the unit (101) and the control loop system (100), depending on how the plant (500) is configured to optimize the state of the unit (101). It will be further appreciated that the data in the feature data set (532) may be stored in a variety of forms, such as a data table, a formula, or a combination of a data table and a formula.

FIG. 6 shows a graphical representation of some of the data that may be included in the pump characterization dataset, which in this embodiment relates to pump performance and reliability characteristics. Graph (602) shows pump pressure difference as a function of pump flow rate and motor rate. Graph (602) also shows the minimum allowable flow rate as a function of motor speed, represented by curve (604), and the maximum allowable flow rate as a function of motor speed, represented by curve (606). Additionally, graph (602) shows a minimum allowable motor speed (608) and a maximum allowable motor speed (610). The graph (602) further includes a curve (612) showing where the pump achieves the best efficiency point or BEP. Finally, two curves (614, 616) show the limits of the preferred operating range of the pump.

Fig. 6 also includes a graph (625) showing pump input power as a function of pump flow rate and motor rate. Graph (625) also shows the minimum allowable flow rate as a function of motor speed, represented by curve (627), and the maximum allowable flow rate as a function of motor speed, represented by curve (629). Additionally, the graph (625) shows a minimum allowable motor speed (631) and a maximum allowable motor speed (633). The graph (625) further includes a curve (635) showing where the pump achieved the BEP. Finally, two curves (637, 639) show the limits of the preferred operating range of the pump.

Fig. 6 also includes: a graph (650) showing pump reliability as a function of motor speed; a graph (675) shows pump reliability as a function of the ratio of pump flow rate to BEP flow rate. In this embodiment, reliability is expressed as a unitless value between 0 and 1, with greater values representing or being equivalent to greater reliability. It should be understood that there are many other possible numerical methods or representations that may be used interchangeably to quantify reliability.

Fig. 7 shows a graphical representation of some of the data in the electric motor characterization dataset, which in this embodiment is related to motor performance and reliability characteristics. Graph (702) shows the maximum output power of a motor as a function of motor speed. The graph (702) also shows a minimum allowable motor speed (708) and a maximum allowable motor speed (710). Additionally, FIG. 7 includes a graph (725) illustrating motor efficiency as a function of motor speed and motor load. The motor load is expressed as a percentage load, which is defined as the ratio of the actual output power of the motor to its rated output power.

Fig. 7 further includes: a graph (750) showing motor reliability as a function of motor speed; and a graph (775) showing motor reliability as a function of motor load. In this embodiment, reliability is expressed as a unitless value between 0 and 1, with greater values equate to greater reliability. It should be understood that there are many other possible numerical methods or representations that may be used interchangeably to quantify reliability.

Fig. 7 also includes a table (780) that shows some additional motor data in tabular form.

FIG. 8 shows a graphical representation of some of the data in the trim control valve characteristic data set that, in this embodiment, is related to trim control valve performance and reliability characteristics. Graph (802) shows a modulating control valve flow coefficient as a function of modulating control valve position. The modulation control valve flow coefficient is a value known to those skilled in the art as a relationship between the flow rate and the differential pressure of the modulation control valve. The graph (802) also shows a minimum allowable valve position (808) and a maximum allowable valve position (810).

FIG. 8 also includes a graph (850) illustrating modulation control valve reliability as a function of valve position. In this embodiment, reliability is expressed as a unitless value between 0 and 1, with greater values equate to greater reliability. It should be understood that there are many other possible numerical methods or representations that may be used interchangeably to quantify reliability.

FIG. 9 shows a graphical representation of some of the data in the control loop characterization data set, which in this embodiment is related to the control loop performance characteristics. Graph (902) shows control loop differential pressure as a function of flow rate when the control valve is fully open.

Returning to the description of fig. 5 and the plant 500, it will be understood that the plant (500) utilizes the signature data set (532) and the input data set (502) to estimate the current state of the unit (101) and the set point of the control loop system (100). Then, as illustrated in fig. 10, the apparatus (500) implements a method (1000) to optimize the state of the unit (101) in the control loop system (100), the method seeking to determine a target state of the unit (101) that minimizes power consumption of the motor (120) and maximizes reliability of the unit (101). The target state is a state that can be achieved by adjusting the speed of the motor (120) to a preferred speed, the target state being in accordance with a set point and being contained within an allowable operating range of a component of the unit (101). The apparatus (500) then controls the speed of the motor (120) by adjusting the voltage and frequency of the output power source (404) via the voltage source inverter (514), thereby driving the motor (120) at a preferred motor speed to achieve the target state.

It will be appreciated that alternative embodiments are readily envisaged in which any component in the apparatus (500) may be divided into a plurality of components and tasks may be divided between the plurality of components. For example, the computer system (522) may be divided into a first computer system that communicates with the inverter (514) and a second computer system that performs the remaining tasks.

Turning to the method, a preferred method (1000) is shown in fig. 10, in this embodiment the priority method utilizes output power as the primary input variable in the data set (502), a pump as the work machine (110), a flow rate sensor as the sensor (130), and a modulating control valve as the final control element (140). The method (1000) is used by the apparatus (500) to optimize the state of the aggregate (101) of the control loop system (100) shown in fig. 4. The method (1000) takes the form of a continuous main loop with some alternative branches for addressing certain situations, as shown in the flow chart in fig. 10. For clarity, the multiple use subroutine (1100) is shown in fig. 10 as a single flow chart element, and in more detail in fig. 11.

As already explained, the set point is maintained by the controller (164) by: feedback from the flow rate sensor (130) is used to adjust the percent travel of the modulating control valve (140). The present invention does not directly affect the set point or adjust the percent travel of the control valve (140). It should be further understood that the first embodiment of the present invention is not in electrical communication with the controller (164) to directly determine the set point, and is not in electrical communication with the flow rate sensor (130) to ascertain the measured flow rate (which may be assumed to be the set point) at steady state.

The method (1000) begins when the device (500) acquires an input data set (502). In this embodiment, the input data set (502) contains a calculated variable representing the output power (550), although in other embodiments, the input data set (502) may contain any number of measured or calculated variables related to the unit (100), such as current, acceleration, speed, displacement, temperature, power, torque, voltage, frequency, pressure, flow, rate, or efficiency.

Next, the method (1000) performs a steady state check (1002) to determine if the control loop system (100) is in steady state, which may be done by evaluating a primary input variable, which in this embodiment is output power (550), at a constant motor speed. If the output power (550) values from the last number of cycles are all within the predetermined steady state tolerance, then the control loop system (100) is determined to be in steady state, the steady state output power (1004) is calculated as an average of the output power (550) values used to determine steady state, and the method (1000) continues with a rate change check (1006). If, however, it is determined that the control loop system (100) is not in a steady state, the method (1000) pauses for a predefined wait time (1007), continues with acquiring the input data set (502), and then returns to the steady state check (1002).

The rate change check (1006) determines the state of a rate change flag (1008) that is set to TRUE (TRUE) when a rate change begins and FALSE (FALSE) when the rate change is complete. If the rate change flag (1008) is TRUE (TRUE), the method (1000) moves to an alternative branch (1050) described later. If the rate change flag (1008) is FALSE (FALSE), the method (1000) continues with a state evaluation subroutine (1100) that evaluates and returns the state of the unit (101) given the motor speed (1102) and the input data set (502), which in this embodiment includes the output power (550).

The subroutine (1100) is shown in fig. 11 as a flowchart. The subroutine (1100) receives the motor speed (1102) and the input data set (502), which in this embodiment is the corresponding output power (1104), when the output power is equal to the output power (550) for this example in the method, and uses the data from the characteristic data set (532) to evaluate and return the status of the unit (101). It will be appreciated that the motor speed (1102) and output power (1104) may be actual measurements (such as output power (550)) or theoretical predicted values, depending on the use in the method (1000).

First, the subroutine (1100) uses the motor speed (1102), corresponding output power (1104), and the feature data set (532) to calculate relevant motor state variables, which may include variables such as input power, output power, efficiency, current, percent load, or any other variable related to the estimated state of the motor (110).

Next, the subroutine (1100) uses the calculated state variables and the feature data set (532) to calculate relevant work machine variables, which in this embodiment are pump state variables, and may include variables such as input power, input torque, output power, output torque, efficiency, flow rate, inlet pressure, outlet pressure, differential pressure, or any other variable related to the estimated state of the pump (110).

Next, the subroutine (1100) uses the calculated state variables and the feature data set (532) to calculate the associated final control element variable, which in this embodiment is a control valve state variable, and may include variables such as valve position, inlet pressure, outlet pressure, differential pressure, or any other variable related to the estimated state of the modulating control valve (140).

Next, the subroutine (1100) uses the calculated state variables and the feature data set (532) to calculate a motor power cost factor (1106), which is a unitless number between 0 and 1, with larger values equate to lower motor power. Specific calculations are not described herein, but it should be understood that there are many numerical methods known in the art that can be used to calculate the motor power cost factor (1106).

Next, the subroutine (1100) uses the calculated state variables and the feature data set (532) to calculate a motor reliability factor (1108), which is a unitless number between 0 and 1, with larger numbers equate to higher motor reliability. Specific calculations are not described herein, but it should be understood that there are many numerical methods known in the art that can be used to calculate the motor reliability factor (1108).

Next, the subroutine (1100) uses the calculated state variables and feature data sets (532) to calculate a work machine reliability factor (1110), which in this embodiment is a pump reliability factor and is a unitless number between 0 and 1, with larger numbers equateing to higher pump reliability. Specific calculations are not described herein, but it should be understood that there are many numerical methods known in the art that can be used to calculate the pump reliability factor (1110).

Next, the subroutine (1100) uses the calculated state variables and the feature data set (532) to calculate a final control element reliability factor (1112), which in this embodiment is a control valve reliability factor and is a unitless number between 0 and 1, with larger numbers equateing to higher control valve reliability. Specific calculations are not described herein, but it should be understood that there are many numerical methods known in the art that can be used to calculate the control valve reliability factor (1112).

Finally, the subroutine (1100) performs an optimization calculation that uses the motor power cost factor (1106), the motor reliability factor (1108), the pump reliability factor (1110), and the control valve reliability factor (1112) to calculate a set value factor (1114), which is a unitless number between 0 and 1. The maximum bank value factor (1114) is equivalent to the optimum state because it has the maximum combined value of motor power cost, motor reliability, pump reliability, and control valve reliability. A specific optimization calculation is not described herein, but it should be understood that there are many numerical methods known in the art that can be used to weight the various factors and calculate the set of numerical factors (1114). Thus, in this embodiment, the estimated states include motor state variables, pump state variables, control valve state variables, and unit value factors (1114). It will be appreciated that the order of computation in the subroutine (1100) may vary. For example, the input data set (502) may include data closely related to the motor (120) and the modulation control valve (140). In this case, the state variables associated with the motor (120) and the regulating control valve (140) may be calculated first, and then the state variables associated with the pump (110) may be calculated from the aforementioned calculated state variables based on such data, which may be included in the characteristic data set (532), which will result in a minimum probability of error.

Referring now back to fig. 10, since the control loop system (100) is in steady state and the current state of the unit (101) is known, the method (1000) then assumes (1012) that the current value of the flow rate (151), which in this embodiment is the process variable, matches the current set point being controlled by the controller (164).

Next, the method (1000) performs a calculation (1016) using the feature data set (532) to create a correlation function (1018) that calculates a predicted primary input variable (which in this embodiment is output power (550)) of the input data set (502) as a function of motor speed. It should be understood that the correlation function (1018) is only valid for the current state of the process variable, in this embodiment the flow rate (151).

Next, the method (1000) performs a calculation (1014) using the feature data set (532) to determine a set of multiple possible rates (e.g., 10 in this embodiment) that can achieve the assumed current setpoint. The 10 possible rates range between the calculated minimum and maximum values and may be equally spaced.

Next, the method (1000) performs a calculation (1020) using the correlation function (1018) and the feature data set (532) to calculate a set of possible values for the primary input variable (output power (550) in this example embodiment) of the input data set (502) and one possible value for each corresponding possible motor speed.

Next, for each possible motor speed, the method (1000) uses a state estimation subroutine (1100) to estimate a corresponding possible state of the unit (101). The state with the maximum set value factor (1114) is considered the optimized state because it has the maximum combination of motor power cost, motor reliability, pump reliability, and control valve reliability. The method (1000) then sets the optimal target rate (1022) equal to the rate corresponding to the state with the maximum bank value factor (1114).

If the target rate (1022) is not equal to the current rate, the method (1000) initiates a rate change by setting a rate change flag (1008) TRUE (TRUE) and adjusting the current rate toward the target rate (1022) by a predefined rate increment (1024). It will be appreciated that after adjusting the current rate, the controller (164) will react by: the position of the modulating control valve (140) is adjusted to maintain the process variable at the set point as measured by the flow rate sensor (130).

Finally, the method (1000) pauses for a wait time (1007), and then returns to the steady state check (1002) and repeats the main loop.

As explained previously, if the rate change flag (1008) is TRUE (TRUE), the method (1000) moves to the alternative branch (1050) after the rate change check (1006). The substitute branch (1050) begins with a correlation function verification check (1052) in which the primary input variables of the input data set (502) are compared to values predicted by the correlation function (1018). In this embodiment, the output power (550) is the actual output power and is compared to a predicted output power (1054) calculated at the actual motor speed using a correlation function (1018). If the actual output power (550) matches the predicted output power (1054) within a predefined tolerance band, the method (1000) continues with a target rate check (1056). If the current rate matches the target rate (1022), the rate change is complete, so the method (1000) sets the rate change flag (1008) FALSE (FALSE), pauses the wait time (1007), and then returns to the steady state check in the main loop (1002). If the current rate does not match the target rate (1022), then the rate change has not been completed, so the method (1000) adjusts the current rate by one increment (1024) toward the target rate (1022), pauses the wait time (1007), and then returns to the steady state check in the main loop (1002).

If the result of the correlation function verification check (1052) is that the output power (550) reflecting the actual output power does not match the predicted output power (1054) within a predefined tolerance band, then it is an indication that the method (1000) is not operating as expected. There may be several reasons for this, such as the controller (164) may have a changed set point, while the method (1000) is in the middle of a rate change. Another possible reason is that the feature data set (532) may contain significant inaccuracies. The method (1000) then adjusts the current rate away from the target rate (1022) by an increment (1024), ends the rate change, and sets the rate change flag (1008) FALSE (FALSE). Optionally, the method (1000) may also log this event into an event log, perform an analysis on the event, and adjust the feature data set (532) to improve its accuracy. The method (1000) then pauses for a wait time (1007) and returns to the steady state check in the main loop (1002).

In the preferred embodiment of the electronic device and method of the present invention shown in fig. 4-11, the device is configured for use in a control loop system configured in a throttle control configuration. However, it will be understood that the disclosure contemplates that one skilled in the art may configure other embodiments in which the control loop system is instead in a bypass control configuration, such as the control loop system (200).

Likewise, in the preferred embodiment of the electronic device and method of the present invention illustrated in fig. 4-11, the device is configured for use in a control loop system comprising a working machine and a final control element, the working machine being a rotodynamic pump and the final control element being a regulating control valve. However, it will be understood that the disclosure contemplates that one skilled in the art may configure other embodiments in which the working machine is instead a fan or blower and the final control element is instead a damper. Further, additional embodiments may have the damper located at the inlet of the work machine, rather than at the outlet.

Similarly, in the preferred embodiment of the electronic apparatus and method of the present invention shown in fig. 4-11, the apparatus is configured for use in a control circuit system that includes a work machine that is a rotodynamic pump, although it is contemplated that other embodiments may alternatively use a positive displacement pump.

Additionally, in the preferred embodiment of the electronic device and method of the present invention shown in fig. 4-11, the device is configured for use in a control loop system that includes an electric motor that operates on AC power, although it is contemplated that additional embodiments may alternatively use an electric motor that operates on DC power.

It will be apparent to those skilled in the art that various modifications may be made in the design and construction of the apparatus and method without departing from the scope or spirit of the claimed subject matter, and that the claims are not limited to the preferred embodiments set forth herein.