PowerFlex 520 Series PID Demo

Summary

In this ESN TV video, VFD specialist Mark Garner explains the use of the PowerFlex 520 series' P mode with trim capabilities. The P mode, integral for maintaining process feedback like pressure or flow, operates by generating an error value based on the difference between the PID feedback and a reference. Garner distinguishes between the single P control loop in the PowerFlex 523 and the two available in the PowerFlex 525, which can only be used one at a time. He illustrates exclusive control in a pumping application and trim control in a winder application, demonstrating how the P mode adjusts motor speed to maintain set points. The video concludes with a practical demonstration using CCW software and emphasizes the importance of consulting the user manual for optimal P tuning.

Takeaways

• 🔧 The Powerflex 520 series drives feature a P (Proportional, Integral, Derivative) control loop designed for maintaining process feedback like pressure, flow, or tension at a set point.
• 🔄 The P Loop operates by calculating the error between the PID feedback and the reference, adjusting the frequency output to minimize this error.
• 📈 Powerflex 523 has one P control loop, while Powerflex 525 has two, though only one can be used at a time.
• 🎛️ Two common configurations for the P Loop are exclusive control and trim control, each serving different automation needs.
• 🚰 In exclusive control, the P output becomes the sole frequency command, as seen in pumping applications where system pressure is the focus.
• 📏 Trim control adds the PID output to the speed reference, useful in applications like winders where tension is managed against a master speed reference.
• 🛠️ Demonstration of P with trim control is shown using CCW software, where the setup includes selecting P1 output, P set point, and analog input for feedback.
• ⚙️ Keypad frequency is adjustable and trims the motor speed in response to changes in analog input voltage, within set limits.
• 📚 P tuning can be complex and may require trial and error; consulting the Powerflex 525 user manual and application notes is advised for optimal setup.
• 🤝 For further assistance or to understand P control theory better, reaching out to a local ESN account manager or automation specialist is recommended.

Q & A

What does 'P' stand for in the context of the PowerFlex 520 series drives?

In the context of the PowerFlex 520 series drives, 'P' stands for Proportional, Integral, Derivative, which are control loop features built into the drives.

How does the P Loop in the PowerFlex 520 series work?

The P Loop works by subtracting the PID feedback from a reference and generating an error value. It then reacts to this error based on the P gains and outputs a frequency to reduce the error value to zero.

What is the difference between PowerFlex 523 and PowerFlex 525 in terms of P control loops?

The PowerFlex 523 has one P control loop, while the PowerFlex 525 has two P control loops, but they can only be used one at a time.

What are the two basic configuration examples where the P Loop may be used?

The two basic configuration examples where the P Loop may be used are exclusive control and trim control.

In a pumping application, how does the P Loop maintain the desired system pressure set point?

In a pumping application, the P reference equals the desired system pressure set point, and the pressure transducer signal provides PID feedback to the drive. Fluctuations in actual system pressure due to changes in flow result in a PID error value, and the drive adjusts the output frequency to correct the P error value, thus maintaining the desired system pressure set point.

How does trim control work in a winder application using the P Loop?

In a winder application, the PID output is added to the speed reference. The P reference equals the equilibrium set point, and the dancer potentiometer signal provides PID feedback to the drive. As tension increases or decreases during the winding, the speed reference is trimmed to compensate, maintaining tension near the equilibrium set point.

What is the purpose of the setup wizard in the CCW software for configuring P with trim control?

The setup wizard in the CCW software is used to configure P with trim control by setting up parameters such as speed reference, P set point, P feedback select, and keypad frequency.

What is the minimum and maximum frequency limits when using P with trim control in the demonstration?

In the demonstration, the minimum frequency limit is 37 Hertz, which is three Hertz below the base frequency of 40 Hertz, and the maximum frequency limit is 43 Hertz.

Why is it recommended to consult the PowerFlex 525 user manual and application notes for setting up PID control?

It is recommended to consult the PowerFlex 525 user manual and application notes for setting up PID control because P tuning can be complex and might require trial and error to achieve optimal results. The manual and notes provide detailed instructions specific to the application.

What is the importance of understanding P control theory for achieving effective and stable control of processes?

Understanding P control theory is important for achieving effective and stable control of processes because it helps in setting up the correct parameters and understanding how the P Loop reacts to errors and adjusts the output frequency accordingly.

Outlines

00:00

🔧 Introduction to PowerFlex 520 Series P Mode with Trim Capabilities

Mark Garner, the VFD specialist, introduces a tutorial on using the PowerFlex 520 series variable frequency drives (VFDs) in P mode with trim capabilities. He emphasizes the importance of subscribing to the ESN TV YouTube channel for more automation content. The P mode, which stands for proportional, integral, and derivative control, is integral for maintaining process feedback such as pressure, flow, or tension at a set point. The P loop's function is explained as the process of subtracting PID feedback from a reference to generate an error value, which it then attempts to reduce to zero by adjusting the output frequency. The differences between the PowerFlex 523, which has one P control loop, and the PowerFlex 525, which has two but can only use one at a time, are highlighted. Two basic configuration examples are given: exclusive control, where the P output becomes the entire frequency command, and trim control, where the PID output is added to the speed reference. A pumping application and a winder application are used as examples to illustrate how the P loop maintains the desired system pressure and tension, respectively.

Keywords

💡Powerflex 520 series

The Powerflex 520 series refers to a line of variable frequency drives (VFDs) manufactured by Allen-Bradley, a Rockwell Automation brand. These drives are used to control the speed and torque of AC induction motors. In the context of the video, the Powerflex 520 series is the main subject, with a focus on its P mode with trim capabilities, which is a feature used for precise control of motor speed in response to process variables.

💡P mode

P mode stands for 'proportional' mode, which is a control mode in the Powerflex 520 series drives. It is part of the proportional-integral-derivative (PID) control loop, where 'P' refers to the proportional control element. The P mode is used to maintain a process variable, such as pressure or flow, at a set point by adjusting the motor speed in proportion to the error between the set point and the process variable. The video explains how to use this mode with trim capabilities for precise control.

💡Trim capabilities

Trim capabilities refer to the ability to fine-tune the output of a control system, such as a VFD, to achieve a desired set point. In the video, trim capabilities are discussed in the context of the P mode, where the output frequency can be adjusted up or down from a base set point to compensate for changes in process conditions. This allows for more precise control, ensuring that the process variable remains stable despite external influences.

💡PID control loop

A PID control loop is a feedback control system that calculates the necessary control action by considering the proportional, integral, and derivative terms of the error between the desired set point and the actual process variable. In the video, the PID control loop is integral to the P mode operation of the Powerflex 520 series, where the 'P' loop is used to adjust motor speed to maintain a process variable at a set point.

💡Set point

A set point in control systems is the desired value of a process variable that the control system aims to achieve and maintain. In the video, the set point is used in the context of the P mode, where the drive adjusts the motor speed to keep the process variable, such as pressure or flow, at the specified set point despite changes in the process conditions.

💡Process feedback

Process feedback refers to the actual measurement of a process variable, such as pressure, flow, or temperature, which is used by the control system to adjust the control action. In the video, process feedback is provided by sensors like pressure transducers or dancer potentiometers, which inform the drive about the current state of the process and help it maintain the set point.

💡Error value

The error value in a control system is the difference between the set point and the process feedback. It is used by the control algorithm to determine the necessary control action. In the video, the error value is calculated by subtracting the PID feedback from the reference, and the P mode reacts to this error to adjust the motor speed and reduce the error to zero.

💡Exclusive control

Exclusive control is a configuration where the P output becomes the sole frequency command to the drive, with the speed reference set to zero. This is discussed in the video as one of the basic configuration examples where the P loop is used. In a pumping application, for instance, the P reference is the desired system pressure set point, and the drive adjusts the motor speed to maintain this pressure despite changes in flow.

💡Trim control

Trim control is a configuration where the PID output is added to the speed reference, allowing for fine-tuning of the motor speed around a base set point. The video provides an example of a winder application where the P reference is the equilibrium set point, and the dancer potentiometer signal provides PID feedback. As tension varies during the winding process, the speed reference is adjusted to maintain tension near the set point.

💡CCW software

CCW software, or ControlLogix ConfigurationWare, is a software tool used to configure and program Allen-Bradley ControlLogix systems, which includes setting up drives like the Powerflex 520 series. In the video, the presenter demonstrates how to use the CCW software to configure the P mode with trim capabilities, adjusting parameters such as the speed reference, P set point, and analog input settings.

💡P tuning

P tuning refers to the process of adjusting the proportional gain within the PID control loop to achieve optimal control of a process. The video notes that P tuning can be complex and may require trial and error. It emphasizes the importance of consulting the user manual and application notes for detailed instructions on setting up PID control, highlighting the need for a solid understanding of P control theory for effective and stable process control.

Highlights

Introduction of Mark Garner as a VFD specialist for ESN, focusing on the PowerFlex 520 series drives.

Encouragement to subscribe to ESN TV YouTube channel for more automation content.

Explanation of the P (proportional-integral-derivative) mode and its role in controlling process feedback like pressure, flow, or tension.

The PowerFlex 520 series uses PID feedback to maintain a setpoint by generating an error value and adjusting frequency accordingly.

Key difference: PowerFlex 523 has one P control loop, while the PowerFlex 525 has two P control loops, but only one can be used at a time.

Two configuration examples of P mode: exclusive control and trim control.

Exclusive control explained using a pumping application, where the drive adjusts motor speed to maintain system pressure setpoint.

Trim control explained using a winder application, where the drive adjusts speed to maintain tension equilibrium.

Demonstration of P with trim control using the CCW software.

In the demonstration, the setup wizard is used to configure speed control, where the speed reference is set to P1 output.

Analog input of 0-10 volts is used as P feedback, with keypad frequency set for 40 Hz and the ability to trim up or down by 3 Hz.

Explanation of how increasing and decreasing voltage affects motor speed, with a lower limit of 37 Hz and upper limit of 43 Hz.

Clarification that P tuning can be complex and may require trial and error for optimal results.

Recommendation to consult the PowerFlex 525 user manual for detailed instructions on PID control setup.

Final reminder that understanding P control theory is essential for stable and effective process control.

Transcripts

hello I'm Mark Garner the vfd specialist

for es& in this video we will be going

over how to use the powerflex 520 series

P mode with trim capabilities but before

we get started please be sure to

subscribe to ESN tv YouTube channel for

more automation

[Music]

content P stands for proportional

integral derivative and our control Loop

features built into the powerflex 520

series of drives the P Loop is used to

maintain a process feedback such as

pressure flow or tension at a desired

set point the P Loop works by

subtracting the PID feedback from a

reference and generating the error value

the P Loop reacts to the error based on

the P gains and outputs a frequency to

try to reduce the error value to zero

it's important to know that the

powerflex 523 has one p control Loop

while the powerflex 525 has two P

control loops however with the 525 they

can only be used one at a time two basic

configuration examples where the P Loop

may be used are exclusive control and

trim control in exclusive control the

speed reference becomes zero and the P

output becomes the entire frequency

command taking a pumping application for

example the P reference equals the

desired system pressure set point the

pressure transducer signal provides the

PID feedback to the drive fluctuations

in actual system pressure due to changes

in flow result in a PID error value the

drive output frequency increases or

decreases to vary motor shaft speed to

correct the P error value the desired

system pressure set point is maintained

as valves in the system are open and

closed causing changes in flow in trim

control the PID output is added to the

speed reference in this example of a

Winder application the P reference

equals the equilibrium set point the

dancer potentiometer signal provides PID

feedback to the drive fluctuations and

tension result in PID error value the

master speed reference sets the wine

unwind speed as tension increases or

decreases during the winding the speed

reference is trimmed to compensate

tension is maintain near the equilibrium

set point now we're going to demonstrate

the p with trim control as we open up

your CCW software as you can see under

the setup wizard you go under speed

control and you can see that our speed

reference is set for P1

output our select is going to be P set

point our P feedback select is going to

be 0 to 10 volts it's going to be our

analog input and we're actually going to

trim on the keypad frequency keypad

frequency is going to be set for 40

HZ we're going to be able to trim go up

and go down three Herz okay we're going

to start the

drive the keypad frequency is set for 40

Herz as you can

see the analog input here is set for 5

volts as I increase the voltage of the

analog input you'll notice that the

frequency is going down so we're

actually slowing the

motor we'll keep increasing as you can

see it will not go below 37 Hertz which

is three Hertz below the 40

as I decrease the 5

volts we'll go back to 40

Hertz and as I keep decreasing the

frequency will rise and the speed will

increase but note we will not go above

43 Hertz that is p with gy

control remember that P tuning can be a

bit complex and might require some trial

and error to achieve optimal results I

highly recommend Consulting the

powerflex 525 user manual and any

relevant application notes to detailed

instructions on setting up PID control

specific to your application having a

solid understanding of P control theory

will greatly help in achieving effective

and stable control of your processes

thank you for watching and if you need

further assistance please reach out to

your local ESN account manager or

automation

[Music]

specialist