Performance analysis of the sliding-mode speed observer with magnetizing reactance estimation for the sensorless induction motor drive
Purpose - The purpose of this paper is to obtain an accurate and robust estimation method of the rotor flux and speed for the sensorless induction motor (IM) drive with magnetizing reactance variations. Design/methodology/approach - The sensorless IM drive with sliding mode flux and speed observer (SMO) is presented. Proposed estimation algorithm is extended with the additional magnetizing reactance estimator based on the magnetizing characteristic of the IM. The dynamical and steady-state properties of the drive system in the low-speed and in the field-weakening regions are tested. The simulation results are verified by experimental tests, over the wide range of motor speed and drive parameter changes. Findings - It is shown that the sensorless induction motor drive can work stable in wide speed range using the Sliding-Mode Observer with additional magnetizing reactance estimator. Research limitations/implications - The investigation looked mainly at the speed estimation methodology with additional motor parameter estimator. Practical implications - The proposed SMO can be easily implemented on digital signal processors. The implementation was tested in an experimental setup with DS1103 card. The fixed-point realisation needs to be developed to obtain the practical application in the industrial drive systems. Originality/value - The SMO with an additional magnetizing reactance estimator based on magnetizing characteristic of the IM is tested. This method of the speed and flux reconstruction can be applied in different electrical drives working in wide speed range, including very low-speed region and field-weakening region, too. The proposed solution is not sensitive to magnetizing reactance variations and is simple in practical implementation in the real-time system.
estimation flux electric motors programming and algorithm theory