Inverter-fed estimation of induction machine fundamental wave parameters at standstill

Abstract

Modern drive systems for induction motors (IM), require accurate knowledge of the motors equivalent circuit parameters. The control scheme in use, utilizes those to operate the IM. When the parameters are unknown but the motor is already connected to its load, conducting standard test might not be possible. Those tests also require trained personal, and thus are costly. In this thesis several identification methods which can be carried out at standstill are investigated. Additionally, the methods should be suitable for self commissioning. This means that they can be performed using a standard power inverter without any additional supply or measurement equipment. For each parameter one or more identification methods are studied in a simulation and with measurements. The stator resistance is identified with a DC-test. The transient inductance is found with a high frequency single phase test, a current and a voltage step test. For estimation of the magnetizing inductance a low frequency single phase test and a DC-decay test are investigated. The rotor resistance is identified with a single phase test and the rotor time constant is estimated with an iterative sinusoidal or flux observer based test. As each method has its advantages and disadvantages, the results of this thesis provide insight on their applicability.