Variable Frequency Drives Course

Course Outline

Introduction

• Evolution of VFD Control
• Modern Types of Variable Frequency Drives (VFD)

Mechanical Theory

• Horsepower Defined
• Torque Defined
• Example Horsepower and Torque Calculations
• Common Types of Mechanical Loads
• Characteristics of Variable Torque and Constant Torque Loads

Basic VFD Electricity Theory

• Electrical/Hydraulic Circuit Analogy
• Resistance, Voltage, and Current Defined

Introduction to AC Motors

• Examination of Motor Nameplates and NEMA Designations
• Locked Rotor Current and Full Load Current
• Anatomy of a Motor
• Magnetic Poles and Frequency as Related to Motor Speed
• Torque Characteristics Motors Operated “Across-the-Line”
• Torque Characteristics of Motors Operated on VFDs
• Effects VFDs on Motor Operation and Life Expectancy

PWM AC VFDs

• Common Types of PWM Drives
• Examination of the Main Power Circuit
• Electronic Component Identification
• The PWM Wave Form
• Voltage and Frequency Relationships and Effects on Motor Performance
• Control of Drive System Torque and Horsepower Output
• Torque Output Comparisons of AC Drives VS. Conventional Means of Speed Control
• Standing Wave (Reflective Wave) Phenomena on Motor Cables
• Disassembly of an AC Drive
• Component Identification
• Various Designs of Drives
• Reassemble, Test, Start-Up of AC Drive With Proper Techniques
• Hands-On Programming and Operation of an AC Drive and Motor
• Adjust Minimum and Maximum Speed
• Reset Drive to Factory Defaults
• Adjusting Torque Output
• General Drive Programming
• Methods of Speed and Torque Control

VFD Applications

• Methods of Proper Drive Selection
• Multi-Motor Drive Systems With Example Problem
• Using VFDs to Eliminate Geared Speed Reducers
• Effects of AC Drives on Geared Speed Reducers
• Replacing Mechanical Speed Changers With VFDs

Conclusion and Summary