Guide to Variable Speed Drives

The Basic Functions of an AC Drive 

This guide continues ABB’s technical guide series, describing different variable speed drives (VSD) and how they are used in industrial processes. Special attention has been given to electrical VSDs and especially to AC Drives. The guide tries to be as practical as possible. No special knowledge of VSDs is required, although basic technical know-how is required to fully understand the terms and descriptions used.

In this diagram, the basic functions of an AC drive are presented. There are four different components in AC drive motor control. These components are the user interface, the motor, the electrical supply and the process interface. An electrical supply feeds the required electricity to the drive; one selection criteria for the drive is the supply voltage and its frequency. The AC drive converts the frequency and voltage and feeds the motor. 

This conversion process is controlled by signals from the process or user via the process and user interfaces. The user interface provides the ability to observe the AC drive and obtain different process information via the drive. This makes the drive easy to integrate with other process control equipment and overriding process control systems.

This article was extracted from "Technical guide No. 4-Guide to variable speed drives" by ABB

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