Parameter estimation of a linear induction motor with PWM inverter

Abstract

Linear induction motors (LIM) are characterized by a large air gap and, as a result, large leakage inductances. Especially, the primary leakage inductance is higher than the secondary leakage inductance. Such a difference prevents the use of a conventional parameter estimation method developed for rotary motors. A parameter estimation scheme for a LIM is proposed that utilizes a PWM inverter. With this method, there is no need to lock or speed up the LIM. It directly yields the mutual inductance by solving a third order polynomial numerically. Direct calculation of the mutual inductance enables calculation of the leakage inductances separately. The proposed estimation scheme is tested with some example models and with a real 20 kW single-side LIM.