VFD Overview

This page covers the VFD overview.  From power electronics to control systems to motor theory.. These are topics that have been brought up during design, installation and troubleshooting drive systems over the past 8 years.

Topics listed without a link are yet to be written. : ) I’ll get there, hopefully at a rate of one a week…


Drive ( and some Motor) Theory:

What is a Variable Frequency Drive?

Input rectifier stage

3 phase power fundamentals

Types of input rectifiers

Filtering- types and effects

6 pulse ,12 pulse and 18 pulse VFD

DC bus- What is the DC bus – Types of capacitors and other components

Output/Inverter Stage

Switching frequencies and its effects

When does regeneration onto the VFD DC bus occur?

Variable Speed Drive, Speed, Torque and Power

Drive applications:

Choosing between VFD’s and Soft Starts

Constant Torque VFD Applications – What happens to voltage, current and power?

Corner grounded systems and its effects on VFD’s

Efficiency of a VFD

Harmonic distortion – power factor, and the effect of capacitors and inductance

PM synchronous vs. AC induction motors

Auto-tuning VFD’s

Noise issues visualized

LTSpice simulation setup for VFD

Effects of cable length on a drive installation

Submersible pumps

Abnormal sounds from a motor driven by a drive

Variable and constant torque

Power factor on a drive installation

Setting up a drive  for pump applications

Submersible pumps and drives- always check drive trip history if there are issues

Line/Load Reactors and Filters

Why is the line reactor noisy?

Can a 3 phase drive run a single phase motor?

Drive Control:

Potentiometer wiring

Sink and source logic inputs and outputs