Parameter estimation scheme for low-speed linear induction motors having different leakage inductances

Abstract

Linear induction motors (LIMs) are characterized by a large air gap and, as a result, large leakage inductances. Moreover, due to its unslotted structure and the absence of end rings in the secondary part, the primary leakage inductance is much larger than the secondary leakage inductance. Such differences prevent us from using parameter estimation methods developed for the rotary motors. We propose a parameter estimation scheme for a LIM that utilizes a pulsewidth-modulation inverter. It yields mutual inductance by numerically solving a third-order polynomial. Direct estimation of mutual inductance enables us to calculate the leakage inductances separately. The proposed estimation scheme is tested with various example models and with a real 20-kW single-sided LIM.