Frank J. Bartos, CONTROL ENGINERING

Articles

Mechatronics and Motion Control November 2, 2018

Sensorless AC Drives Fill Price/Performance Niche

KEY WORDSMotors, drives, & motion controlAC variable-speed drivesAC induction motorsAdaptive controlControversial right from their name, "sensorless" ac drives actually use current and voltage sensors to achieve motor control. Even beyond terminology, it's not obvious what sensorless ac drives can or can't do, and where they fit into the big picture.

By Frank J. Bartos, CONTROL ENGINERING
Motors and Drives March 1, 2001

Today’s Sensorless AC Drives Have More to Offer

A djustable-speed ac drives operating without an encoder or other external feedback device-so-called sensorless drives-represent a growing middleground between high-performance closed-loop control and simpler Volts/Hertz control for induction motors. As explained in the main article , a good deal of sensorless drives' popularity stems from improvements in speed regulation under changing loads, starting torque, and low-speed control. Most sensorless ac drives are based on one of various flux vector methods-loosely named sensorless vector (SV) control. Control Techniques (Eden, Prairie, Minn.; Newtown, Powys, U.K.) sees a definite emergence of sensorless vector control because of the improved dynamic performance it offers over open-loop (V/Hz) control.

By Frank J. Bartos, CONTROL ENGINERING