Variable Frequency Drives - Volume I

In Variable Frequency Drives - Volume I, you'll learn ...

• The operating principles and performance characteristics of AC induction and synchronous motors
• The relationship between motor frequency, voltage, torque, speed, and energy consumption in VFD applications
• The internal architecture and control methods used by modern Variable Frequency Drives
• The impact of harmonics and power quality considerations on electrical systems utilizing VFD technology

Overview

Preview a portion of this course before purchasing it.

Credit: 5 PDH

Length: 81 pages

This course provides a comprehensive introduction to Variable Frequency Drives (VFDs) and their application in controlling AC electric motors. The advent of sophisticated electronics has enabled VFD technology to control motor speeds to match the need for a give application. This technology can improve electric motor reliability, make it easier to adjust speed, and reduce operating costs.

The course begins with a review of AC motor fundamentals, including induction motors, synchronous motors, rotating magnetic fields, synchronous speed, slip, torque production, and motor performance characteristics. The course explains how VFDs regulate motor speed and torque by controlling voltage and frequency, enabling improved process control and significant energy savings.

Participants will learn how VFDs reduce energy consumption in centrifugal loads such as pumps and fans through the application of fluid affinity laws. The course also examines the mechanical and electrical benefits of VFDs, including reduced inrush current, lower equipment wear, improved power quality, and demand charge reduction. A detailed review of VFD internal architecture is presented, covering rectification, DC bus operation, pulse width modulation (PWM), inverter technology, V/Hz control, vector control, dynamic braking, and regenerative drives.

The course concludes with an in-depth discussion of harmonics, power quality issues, Total Harmonic Distortion (THD), IEEE 519 considerations, and practical harmonic mitigation techniques.

Specific Knowledge or Skill Obtained

This course teaches the following specific knowledge and skills:

• The creation and behavior of rotating magnetic fields in three-phase AC motors
• The calculation and significance of synchronous speed, slip, and torque production in induction motors
• The differences between constant torque and variable torque loads and their effect on VFD selection
• The application of fluid affinity laws to estimate energy savings in pumps, fans, and blowers
• The comparison of traditional throttling methods and variable speed control strategies
• The three-stage power conversion process consisting of rectification, DC bus filtering, and inversion
• The operation of Pulse Width Modulation (PWM) and IGBT-based inverter technology
• The implementation of V/Hz control, vector control, and constant horsepower operation
• The management of regenerative energy through dynamic braking and regenerative drive systems
• The identification, measurement, and mitigation of harmonic distortion in VFD-powered electrical systems

Certificate of Completion

You will be able to immediately print a certificate of completion after passing a multiple-choice quiz consisting of 34 questions. PDH credits are not awarded until the course is completed and quiz is passed.