Rockwell Automation Allen-Bradley PowerFlex 755T Flux Vector Tuning User Manual

110 Rockwell Automation Publication 750-AT006D-EN-P - January 2022
Chapter 7 Applications
Options include DPI adapter ports, MOP, preset speeds, analog inputs, pulse input, encoder input, and PID setpoint parameter. The value that
is used for reference is displayed in 9:26 [PID Ref Meter]. The value that is used for feedback is displayed in 9:36 [PID Fdbk Meter]. These
displays are active independent of PID enabled. Full scale is displayed as ±100.00%.
PID Reference and Feedback Scaling – The analog PID reference can be limited by using 9:29 [PID Ref AnlgHi] and 9:30 [PID Ref AnlgLo].
9:29 [PID Ref AnlgHi] determines the high value, in percent, for the analog PID reference. 9:30 [PID Ref AnlgLo] determines the low value, in
percent, for the PID reference.
The analog PID feedback can be limited by using 9:39 [PID Fdbk AnlgHi] and 9:40 [PID Fdbk AnlgLo]. 9:39 [PID Fdbk AnlgHi] determines the
high value, in percent, for the PID feedback. 9:40 [PID Fdbk AnlgLo] determines the low value, in percent, for the PID feedback.
An example is when 9:26 [PID Ref Meter] and 9:36 [PID Fdbk Meter] are displayed as positive and negative values. Feedback from a dancer
comes into Analog Input 2 as a 0…10V DC signal.
9:25 [PID Ref Sel] = PI Setpoint (0)
9:28 [PID Setpoint] = 50%
9:35 [PID Fdbk Sel] = Analog In 2 (2)
9:29 [PID Ref AnlgHi] = 100%
9:30 [PID Ref AnlgLo] = –100%
9:39 [PID Fdbk AnlgHi] = 100%
9:40 [PID Fdbk AnlgLo] = 0%
The PI Feedback Scaling is:
Now 5V corresponds to 50% on the PID feedback, and we try to maintain a PID setpoint of 50% (5V).
9:9 [PID Deadband] – This parameter conditions the PID reference. If the PID reference has undesired rapid changes, the deadband can help
smooth out these transitions.
PID Setpoint – This parameter can be used as an internal value for the setpoint or reference for the process. If 9:25 [PID Ref Sel] points to
this parameter, the value entered here becomes the equilibrium point for the process.
PID Error – The PID error is then sent to the proportional and integral functions, which are summed together. 9:10 [PID LPF BW] sets the
bandwidth of a first order low pass filter that is applied to the PID error. This is useful in filtering out unwanted signal response, such as
noise in the PID feedback signal.
10:2000 [Trq Ref A Sel] = Analog In 1
X:61
(1)
[Anlg In1 Hi] = 10V
where X denotes the port of your I/O module
(1) The variable X is used because this parameter can be assigned to any port and is not specific to any application.
X:62
(1)
[Anlg In1 Lo] = 0V
where X denotes the port of your I/O module
9:39 [PID Fdbk AnlgHi] = 100%
9:40 [PID Fdbk AnlgLo] = 0%

Rockwell Automation Allen-Bradley PowerFlex 755T Flux Vector Tuning Specifications

General

Model	PowerFlex 755T
Type	AC Drive
Input Frequency	50/60 Hz
Control Method	Flux Vector Control
Communication Protocols	EtherNet/IP, ControlNet, DeviceNet
Cooling Method	Air-cooled
Safety	Safe Speed Monitor
Motor Control	Induction

Summary

Chapter 1 Background

Mechanical Loading

Explains mechanical properties influencing drive performance, including inertia, compliance, and backlash.

Resonances

Describes system oscillations, their types (LF, MF, HF), and how they affect tuning.

Performance Metrics

Details key metrics for tuning: Bandwidth, Damping Factor, System Bandwidth, and System C/U Select.

Control Structure Overview

Provides an overview of the drive's internal control structure and feature locations.

Chapter 2 Product Features

Torque Scaler

Accounts for load inertia and scales torque to match velocity loop bandwidth.

Load Observer

Estimates and compensates for mechanical load, improving tuning simplicity and performance.

Adaptive Tuning

Automatically monitors and adjusts filters and gains to compensate for changing load conditions.

Notch Filters

Second-order filters used to suppress specific resonant frequencies in the torque loop.

Chapter 3 Out-of-Box Tuning

Out-of-Box Tuning Basics

Describes default control loop gain settings for satisfactory performance without tuning.

Recommended Default Settings

Provides steps to configure the drive for high performance out-of-the-box.

Single Knob Tuning

Uses one parameter to adjust system bandwidth and performance.

Chapter 4 Auto Tuning

Auto Tuning Function

Measures motor characteristics, including electrical parameters and inertia.

Motor Electrical Parameters

Details static and dynamic tests for measuring motor electrical properties.

Inertia Tests

Tests to measure motor inertia and total inertia for accurate calculations.

Gain Calculation

Calculates control loop gains and dynamic limits based on measured parameters.

Chapter 5 Manual Tuning

Manual Tuning Method

Step-by-step process for tuning current, velocity, and position loops incrementally.

Tune the Current Loop (Optional)

Procedure for manually tuning the current control loop for optimal performance.

Tune the Velocity Loop

Steps for manually tuning the velocity control loop for stability and responsiveness.

Tune the Position Loop (Optional)

Procedure for manually tuning the position control loop to achieve desired stability.

Chapter 6 Active Front End Tuning

AFE Functionality and Topology

Describes the Active Front End topology, LCL filter, and control loops.

Voltage Regulator Tuning

Parameters and calculations for tuning the DC bus voltage regulator.

DC Bus Observer

Estimates and compensates for DC bus load disturbances for improved performance.

Phase Locked Loop (PLL)

Algorithm for estimating grid angle and frequency, crucial for AFE operation.

Power Disturbance Module

Detects abnormal grid conditions like voltage sags and phase loss.

Reactive Power Control

Manages reactive power flow to enhance power factor and system efficiency.

Chapter 7 Applications

Friction Compensation

Overcomes static, sliding, and viscous friction effects in mechanical systems.

Vertical Loads

Considerations for tuning drives with vertical loads and electronic counter-balance methods.

Process PID Controller

Implements closed-loop process control for speed or torque regulation.

PID Features

Explains PID preload, ramp reference, zero clamp, and other controller features.

Additional Resources

Rockwell Automation Support

Provides access to technical support, knowledgebase, and phone numbers.

Documentation Feedback

Mechanism for providing suggestions to improve documentation content.