Drive Fundamentals. Motor Control Bootcamp May 15-18, Copyright 2015 Rockwell Automation, Inc. All Rights Reserved. PUBLIC CO900H

Transcription

1 CO900H Drive Fundamentals Motor Control Bootcamp May 15-18, 2017

2 How are these Devices Related? Variable frequency drives Variable speed drives Variable speed controllers Adjustable frequency drives Adjustable speed drive Adjustable speed controllers

3 Benefits of Drives Better process control Reduce mechanical stress in systems Decrease wasted energy Increase safety of machinery Increased information about a process Increased reliability of systems

4 Typical Low Voltage VFD

5 What is an IGBT? IGBT = Isolated-gate bipolar transistor Power semi conductor device that turns on/off at a rate up to 0.1 us. Has low losses Device of choice for most modern 600V VFD manufacturers. Electrical Symbol Used in many devices today: 1. Variable-Frequency Drives (VFDs) 2. Electric cars, 3. Trains 4. Variable speed refrigerators 5. Air-conditioners 6. Stereo systems

6 Drive Control Options Volts/Hertz Basic control method, providing a variable frequency drive for applications like fan and pump It provides fair speed and starting torque, at a reasonable cost Sensorless Vector Flux Vector Provides better speed regulation Ability to produce a high starting torque Provides more precise speed and torque control with dynamic response Field Oriented Control Provides the best speed and torque regulation available for AC motors Provides DC like performance for AC motors Well suited for typical DC applications Lowest Performance Highest Performance Lowest Torque/Amp Highest Torque/Amp

7 Volts / Hertz Control

8 Sensorless Vector

9 Flux Vector

10 Field Oriented Control

11 Volts / Hertz to Vector to FOC Control Constant Torque Constant Flux

12 Power / Torque Base Speed Speed Torque Relationship Torque = HP * 5252 Rated RPM Constant Torque Constant Flux Constant Power Field Weakening Voltage > power output or HP Frequency > speed or RPM Current > torque. Speed Speed = 120*Hz / # of Poles of the Motor Torque = K * V/HZ * I HP = Torque*Speed / 5252

13 Size the Drive Properly (Hint DON T USE HP) Size the Inverter based on Nameplate FLA and Overload Requirement

14 Types of Loads Variable Torque Constant Torque Constant Horsepower Torque HP 75 Torque & HP 50 Torque & HP % Speed 100 % Speed

15 Load Examples Constant Torque applications: (Typical OL 150% / 60 secs) Steel mills machines, Paper machines (winder, tension reels, mill stands) Cement mills, rubber mills, mixers, crushers Conveyors Positive displacement pumps Variable Torque applications: (Typical OL 110% / 60 secs) Centrifugal pumps Chilled water, chiller, pressure boosting, cooling tower, wastewater, and pipeline pumps Air and refrigeration compressors Centrifugal fans Supply, return, cooling tower, ventilation, and dryer fans The mode of drive should match the application

16 Centrifugal Load Properties

17 Load Properties Friction Conveyor Friction Friction

18 What is Autotune? Autotune is used to measure motor and cable characteristics Although the parameter values can be changed manually, the best performance of the drive will be with measured values of the motors characteristics There are 5 states of AutoTune 0 = Ready 1 = Calculate 2 = Static Tune 3 = Rotate Tune 4 = InertiaTune OR

19 What is Autotune? (cont d) Tests done during an AutoTune Resistance Test Used to measure Stator resistance Inductance tests This test will be a Static test whether "Static" or "Rotate" is selected. The result from the Induction test is placed into the IX0 parameter Flux Test This test will be a Rotate test which measures the current under a no load condition. The results are used for the flux current. Slip Test This test will be a Rotate test which measures the difference between the rotor speed and the stator speed. This measurement is taken during acceleration. PM Offset Test This test may create a small amount of motor movement so will need to be performed with the Rotate selection. The test will read the encoder position when the drive outputs zero hertz. Inertia Test This test is a stand alone test which is used to measure the system inertia. The drive sets this value in parameter 76 [Total Inertia] as seconds of inertia. This reflects the time it takes to accelerate the load at 100% torque to base speed. This information can be very useful in determining the total inertia (in lbft 2 ) that is connected to a motor shaft.

20 Autotune and Mode of Operation? What do you think based on previous slides?

21 Autotune and Mode of Operation? What do you think based on previous slides?

22 Autotune and Mode of Operation? What do you think based on previous slides?

23 Autotune and Mode of Operation? What do you think based on previous slides?

24 Autotune and Mode of Operation? What do you think based on previous slides?

25 Autotune and Mode of Operation? What do you think based on previous slides?

26 Drive Fundamentals