A new induction motor drive based on the flux vector acceleration method

A novel control strategy for the induction motor drive, based on the field acceleration method, is presented. The torque is controlled through variations of the stator flux angular velocity. The stator flux is controlled by using a feedforward control scheme, with the stator flux reference vector adjusted so as to obtain the fixed rotor flux amplitude. The applied controller assures a fast torque response, low torque ripple in the steady state, and drive operation with a constant switching frequency. The algorithm includes the improved stator and rotor flux estimation that guarantees the stable drive operation in all operating conditions, even at low speeds. The experimental tests verify the performance of the proposed algorithm, proving that good behavior of the drive is achieved in the transient and steady-state operating conditions.

I. Introduction

The INDUCTION motor drives with variable supply frequency are widely used in industry for the motion control, traction, and general automation. The effort in developing novel control structures is focused on the drives having a minimum number of sensors and measurement points required for the operation, monitoring, and drive protection. A wide range of speed-sensorless solutions has been proposed, resulting in a significant improvement of performance at higher speeds, but failing to improve the drive behavior below 1% of the rated speed.