Torque Production with AC Drives and Motors: Understanding the Technology, 2001 Process Control, Electrical & Info. Conference Proceedings

Roy M. Anderson--AC Drives and Motors perform operations that historically were performed by other technologies such as DC Drives and Motors. The difference however is that in our DC Drive history, DC Motors were variable speed devices by design. This is not true for AC Motors. Most AC Motors were historically designed for operation in across-the-line, fixed speed applications. The introduction of variable speed AC Drives and their exponential acceptance over the past 25 years enabled users of these drive products to add this variable speed flexibility to what was once a fixed speed operation.

These AC Drives come in many design variations: Volts/Hertz, sensorless vector control, flux vector control, field-oriented control, etc....label the types of techniques AC Drives use to operate AC Motors. Each technique manipulates current and frequency differently, and use diverse methods to optimize performance due to temperature changes in motors. Understanding these differences as well as how the motor interacts with the drive can be crucial to your application if not correctly considered during the specifying stage of a project.