Performance and Characteristics of Induction Motors for Solid-State Variable Frequency Drives

Polyphase induction motors used in static variable frequency drive systems are versatile torque transducers having operating characteristics and features which meet the requirements of modern variable speed drive systems. Some of these characteristics are the capability for operation at very low and high speeds, at high-torque overloads, in a constant horsepower versus speed mode, and in the negative torque range for regenerative and dynamic braking. Attractive features include the easy availability of wide ranges in horsepower, voltage, and speed ratings as well as varied construction configurations. Additionally, induction motors have size, weight, torque-to-inertia ratios, and certain cost advantages when compared to dc drive motors.